| 1. |
- Das, Oisik, et al.
(författare)
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Naturally-occurring bromophenol to develop fire retardant gluten biopolymers
- 2020
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Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 243
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to impart fire retardancy in wheat gluten polymer through naturally-occurring additives such as lanosol. The fire properties of lanosol were compared with two other conventional brominated fire retardants (Tetrabromobisphenol A and Hexabromocyclododecane). Samples containing fire retardants and gluten were prepared through compression moulding process and then characterised for their fire and mechanical properties. All fire retardants enhanced the reaction-to-fire and thermal properties of gluten while generating V-0 (i.e. vertical position and self-extinguished) ratings in the UL-94 test. The presence of all the fire retardants increased the modulus of the gluten polymer but the fire retardant particles were detrimental for the tensile strength. Nevertheless, lanosol addition delayed ignition and lowered peak heat release rate of gluten by the maximum amount, thereby leading to relatively higher fire performance index (compared to the other fire retardants). Lanosol also allowed the gluten to create a dense char barrier layer during burning that impeded the transfer of heat and flammable volatiles. The fact that only 4 wt% lanosol was able to cause self-extinguishment under direct flame and reduce peak heat release rate by a significant 50% coupled with its inherent occurrence in nature, raises the question if lanosol can be a potential fire retardant in polymeric systems, although it is a bromophenol.
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| 2. |
- Andersson, Helene, 1983, et al.
(författare)
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Effects of molecular weight on permeability and microstructure of mixed ethyl-hydroxypropyl-cellulose films
- 2013
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 48:1-2, s. 240-248
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Tidskriftsartikel (refereegranskat)abstract
- Films of ethyl cellulose (EC) and water-soluble hydroxypropyl cellulose (HPC) can be used for extended release coatings in oral formulations. The permeability and microstructure of free EC/HPC films with 30% w/w HPC were studied to investigate effects of EC molecular weight. Phase separation during film spraying and subsequent HPC leaching after immersion in aqueous media cause pore formation in such films. It was found that sprayed films were porous throughout the bulk of the films after water immersion. The molecular weight affected HPC leaching, pore morphology and film permeability; increasing the molecular weight resulted in decreasing permeability. A model to distinguish the major factors contributing to diffusion retardation in porous films showed that the trend in permeability was determined predominantly by factors associated with the geometry and arrangement of pores, independent of the diffusing species. The film with the highest molecular weight did, however, show an additional contribution from pore wall/permeant interactions. In addition, rapid drying and increasing molecular weight resulted in smaller pores, which suggest that phase separation kinetics affects the final microstructure of EC/HPC films. Thus, the molecular weight influences the microstructural features of pores, which are crucial for mass transport in EC/HPC films.
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| 3. |
- Hosseini, Seyedehsan, 1994
(författare)
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Additive-Driven Improvements in Interfacial Properties and Processing of TMP-Polymer Composites
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Efforts to address environmental concerns have resulted in new regulations designed to plan the reduction of plastic and synthetic polymer usage, necessitating the search for sustainable natural alternatives with comparable cost-effectiveness and mechanical performance. Thermomechanical pulp (TMP) fibres are one of the most affordable natural fibres that have no chemical refining in production, production have a high yield of 90-98% and TMP fibres have been demonstrated to improve the mechanical characteristics (strength, stiffness and toughness) of wood-polymer composites (WPCs) compared to the pure polymer. The integration of TMP fibres with non-polar synthetic polymers remains a challenge due to surface polarity differences. This PhD thesis aims to ease the processing of TMP fibre composites through the incorporation of additives. The hypothesis posits that incorporating magnesium stearate (MgSt), molybdenum disulfide (MoS2) and alkyl ketene dimer (AKD) as additives in TMP composites will enhance interfacial properties, resulting in improved processability and flow behaviour at high temperatures. MoS2 is known for its interaction with lignin, which exists in TMP and MgSt is recognised for its ability to improve flow in pharmaceutical processing when combined with cellulose, also a component of TMP. AKD modifies the hydrophilic properties of lignocellulosic surfaces. The experimental work explores the effect of these additives on the properties of TMP composites of ethylene acrylic acid copolymer (EAA) and polypropylene (PP) matrices. The dynamic mechanical analysis (DMA) and mechanical analysis results reveal that MoS2 exhibits superior interaction with TMP fibres, yielding enhanced interfacial properties compared to MgSt in between EAA and TMP fibres. Rheological studies elucidate the transition from a fluid-like state to a network-like structure upon the incorporation of TMP into the PP matrix. The incorporation of AKD with C18 reduces the viscosity of TMP-PP composites and PP itself, and, as determined through theoretical Hansen solubility parameter (HSP) calculations, increases compatibility between cellulose in TMP fibres and PP. The addition of AKD influences both the colour (lighter) and shape (smoother surface) of the extrudate filaments in the TMP-PP composites, indicative of improved processing. In addition, frictional analysis demonstrates the reduction of the coefficient of friction (COF) between metal and TMP fibre by MgSt and AKD treatments.
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| 4. |
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| 5. |
- Vera, C. M., et al.
(författare)
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A preliminary study on the selectivity of linear polynuclear aromatic hydrocarbons in SFC using phenyl-type stationary phases
- 2015
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Ingår i: Microchemical journal (Print). - : Elsevier. - 0026-265X .- 1095-9149. ; 121, s. 136-140
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Tidskriftsartikel (refereegranskat)abstract
- The retention behaviour of a homologous series of polyaromatic hydrocarbons was evaluated on two phenyl-type stationary phases in reversed phase supercritical fluid chromatography (SFC). These phases were the Synergi polar-RP phase and the Cosmosil 5PBB phase, both of which are polar end-capped and incorporate an ether in a propyl chain that tethers the phenyl ring to the silica surface. The Cosmosil 5PBB phase also has five bromine atoms on the phenyl ring. The retention capacity of the Cosmosil column was substantially greater than the Synergi column. However, selectivity on the Cosmosil column was effectively independent of the acetonitrile modifier composition in the CO2 mobile phase, whereas, selectivity on the Synergi column was greatly affected by the acetonitrile modifier in the CO2 mobile phase. The results from this study showed that selectivity and retention studies in HPLC cannot be used to predict selectivity and retention behaviour in SFC. (C) 2015 Elsevier B.V. All rights reserved.
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| 6. |
- Decrop, Deborah, et al.
(författare)
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Single-step manufacturing of femtoliter microwell arrays in a novel surface energy mimicking polymer
- 2015
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Ingår i: 18th International Conference on Solid-State Sensors, Actuators and Microsystems (IEEE TRANSDUCER 2015). - : IEEE.
-
Konferensbidrag (refereegranskat)abstract
- We report a novel polymer material formulation and stamp-molding technique that enable rapid single-step manufacturing of hydrophilic-in-hydrophobic microwell arrays. We developed a modified thiol-ene-epoxy polymer (mOSTE+) formulation that mimics the surface energy of its mold during polymerization. The polymer inherits the surface energy from the mold through molecular self-assembly, in which functional monomers self-assemble at the interface between the liquid prepolymer and the mold surface. Combining this novel mOSTE+ material with a stamp-molding process leads to simultaneous surface energy mimicking and micro-structuring. This method was used to manufacture microwells with hydrophilic bottom and hydrophobic sidewall, depressed in a surrounding hydrophobic surface. The microwell arrays were successfully tested for the self-assembly of 62’000 femtoliter-droplets. Such femtoliter droplet arrays are useful for, e.g., digital ELISA and single cell/molecule analysis applications.
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| 7. |
- Danish, Muhammad, et al.
(författare)
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Effect of solution matrix and pH in Z-nZVI-catalyzed percarbonate system on the generation of reactive oxygen species and degradation of 1,1,1-trichloroethane
- 2017
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Ingår i: Water Science and Technology. - London, UK : IWA PUBLISHING. - 1606-9749 .- 1607-0798. ; 17:6, s. 1568-1578
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Tidskriftsartikel (refereegranskat)abstract
- This study primarily focuses on evaluating the effects of solution matrix and pH for the generation of reactive oxygen species (ROSs) in a Z-nZVI-catalyzed sodium percarbonate (SPC) system to degrade 1,1,1-trichloroethane (1,1,1-TCA) in the absence and presence of a reducing agent (RA), i.e. hydroxylamine. Degradation of 1,1,1-TCA was 49.5% and 95% in the absence and presence of RA. Probe tests confirmed the generation of major hydroxyl radicals (OH center dot) and minor superoxide species (O-2(-center dot)), and scavenger tests verified the key role of OH center dot and less of O-2(-center dot) radicals. Degradation of 1,1,1-TCA decreased significantly in the presence of Cl- and HCO3-, while NO3- and SO42- had negligible effects in the absence of RA. Addition of RA significantly enhanced 1,1,1-TCA degradation by generating more OH center dot and O-2(-center dot) radicals in the presence of anions. Degradation of 1,1,1-TCA increased in the acidic range (1-5), while an inhibitive trend from neutral to basic (7-9) was observed. In contrast, a significant increase in 1,1,1-TCA degradation was observed with the addition of RA at all pH values (1-9). In conclusion, the anions and pH significantly influenced the generation and intensity of ROSs and 1,1,1-TCA was effectively degraded in the Z-nZVI-catalyzed SPC system in the presence of RA.
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| 8. |
- George, Zandra, 1985, et al.
(författare)
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Two-in-one : Cathode modification and improved solar cell blend stability through addition of modified fullerenes
- 2016
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 4:7, s. 2663-2669
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of dual purpose modified fullerenes with pyridine-as well as amine-functional groups is reported. Addition of these fullerenes to a polymer : fullerene bulk-heterojunction blend based on a thiophene-quinoxaline donor polymer is found to modify the active layer/cathode interface of inverted solar cells (glass/ITO/active layer/MoO3/Al). In particular the open-circuit voltage of devices is increased from 0.1 V to about 0.7 V, which results in a drastic rise in photovoltaic performance with a power conversion efficiency of up to 3%. At the same time, presence of the functionalised fullerene additives prevents the detrimental formation of micrometre-sized fullerene crystals upon annealing at 140 degrees C. As a result, the device performance is retained, which promises significantly increased thermal stability of the bulk-heterojunction blend nanostructure.
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| 9. |
- Javed, Asif, 1982-, et al.
(författare)
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Lignin-containing coatings for packaging materials—pilot trials
- 2021
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 13:10
-
Tidskriftsartikel (refereegranskat)abstract
- One severe weakness of most biopolymers, in terms of their use as packaging materials, is their relatively high solubility in water. The addition of kraft lignin to starch coating formulations has been shown to reduce the water solubility of starch in dry coatings. However, lignin may also migrate into aqueous solutions. For this paper, kraft lignin isolated using the LignoBoost process was used in order to examine the effect of pH level on the solubility of lignin with and without ammonium zirconium carbonate (AZC). Machine-glazed (MG) paper was coated in a pilot coating machine, with the moving substrate at high speed, and laboratory-coated samples were used as a reference when measuring defects (number of pinholes). Kraft lignin became soluble in water at lower pH levels when starch was added to the solution, due to the interactions between starch and lignin. This made it possible to lower the pH of the coating solutions, resulting in increased water stability of the dry samples; that is, the migration of lignin to the model liquids decreased when the pH of the coating solutions was reduced. No significant difference was observed in the water vapor transmission rate (WVTR) between high and low pH for the pilot-coated samples. The addition of AZC to the formulation reduced the migration of lignin from the coatings to the model liquids and led to an increase in the water contact angle, but also increased the number of pinholes in the pilot-coated samples. © 2021 by the authors
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| 10. |
- Khataee, Amirreza, et al.
(författare)
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Asymmetric cycling of vanadium redox flow batteries with a poly(arylene piperidinium)-based anion exchange membrane
- 2021
-
Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 483
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Tidskriftsartikel (refereegranskat)abstract
- The potential application of a 50 μm thick anion exchange membrane prepared based on poly(terphenyl piperidinium-co-trifluoroacetophenone) (PTPT) is investigated for vanadium redox flow batteries (VRFBs). The PTPT exhibits a considerably lower vanadium permeation than Nafion 212. Therefore, the self-discharge duration of the VRFB based on PTPT is much longer than the VRFB based on Nafion 212. Besides, PTPT shows oxidative stability almost as good as Nafion 212 during immersion in an ex-situ immersion test for more than 400 h. Comparing the VRFB performance when symmetric and asymmetric electrolyte volumes are used yields interesting results. The results show that asymmetric cycling is more effective and efficient for the VRFB assembled with PTPT than Nafion 212 as the capacity fade of 0.03% cycle−1, and the highest coulombic efficiency of 98.8% is attained. Furthermore, the color change of the membrane during cycling can be reversed using a straightforward post-treatment method.
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| 11. |
- Nyflött, Åsa, 1986-, et al.
(författare)
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The influence of moisture content on the polymer structure of polyvinyl alcohol in dispersion barrier coatings and its effect on the mass transport of oxygen
- 2017
-
Ingår i: JCT Research. - : Springer. - 1547-0091 .- 2168-8028. ; , s. 1345-1355
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a study of the effect of moisture on the gas permeability of polyvinyl alcohol (PVOH) and PVOH–kaolin dispersion barrier coatings. The oxygen permeability was measured at different humidity levels, and the material properties were characterized under the same conditions: polymer crystallinity, kaolin concentration, and kaolin orientation were all evaluated. The experimental results revealed that the water plasticizes the PVOH material of the coatings, and the presence of kaolin filler is unable to affect such behavior significantly. The PVOH crystallinity was affected drastically by the humidity, as water melts polymer crystallites, which is a reversible process under removal of water. The permeability data were analyzed using a thermodynamicbased model able to account for the water effect on both the solubility of the gas and the diffusivity coefficients in the polymer and composite. The results showed good agreement between the model’s predictions and the experimental data in terms of the overall permeability of the material.
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| 12. |
- Zubritskaya, Irina, 1984, et al.
(författare)
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Dynamically Tunable Optical Cavities with Embedded Nematic Liquid Crystalline Networks
- 2023
-
Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 35:13
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Tidskriftsartikel (refereegranskat)abstract
- Tunable metal–insulator–metal (MIM) Fabry–Pérot (FP) cavities that can dynamically control light enable novel sensing, imaging and display applications. However, the realization of dynamic cavities incorporating stimuli-responsive materials poses a significant engineering challenge. Current approaches rely on refractive index modulation and suffer from low dynamic tunability, high losses, and limited spectral ranges, and require liquid and hazardous materials for operation. To overcome these challenges, a new tuning mechanism employing reversible mechanical adaptations of a polymer network is proposed, and dynamic tuning of optical resonances is demonstrated. Solid-state temperature-responsive optical coatings are developed by preparing a monodomain nematic liquid crystalline network (LCN) and are incorporated between metallic mirrors to form active optical microcavities. LCN microcavities offer large, reversible and highly linear spectral tuning of FP resonances reaching wavelength-shifts up to 40 nm via thermomechanical actuation while featuring outstanding repeatability and precision over more than 100 heating–cooling cycles. This degree of tunability allows for reversible switching between the reflective and the absorbing states of the device over the entire visible and near-infrared spectral regions, reaching large changes in reflectance with modulation efficiency ΔR = 79%.
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| 13. |
- Nyflött, Åsa, 1986-
(författare)
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Structure-Performance Relations of Oxygen Barriers for Food Packaging
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Food packaging should ensure the safety and quality of food, minimize spoilage and provide an easy way of storing and handling it. Barrier coatings are generally used to meet the demands placed on fibre-based food packages, as these have the ability to regulate the amount of gases that can enter them. Some gases are detrimental to food quality: oxygen, for example, initiates lipid oxidation in fatty foods. Using both experimental data and computer modelling, this thesis explains some aspects of how the structure of barrier coatings influences the mass transport of oxygen with the aim of obtaining essential knowledge that can be used to optimize the performance of barriers.Barrier coatings are produced from polyvinyl alcohol and kaolin blends that are coated onto a polymeric support. The chemical and physical structures of these barriers were characterized according to their influence on permeability in various climates. At a low concentration of kaolin, the crystallinity of polyvinyl alcohol decreased; in the thinner films, the kaolin particles were orientated in the basal plane of the barrier coating. The experimental results indicated a complex interplay between the polymer and the filler with respect to permeability.A computer model for permeability incorporating theories for the filled polymeric layer to include the polymer crystallinity, addition of filler, filler aspect ratio and surrounding moisture was developed. The model shows that mass transport was affected by the aspect ratio of the clay in combination with the clay concentration, as well as the polymer crystallinity. The combined model agreed with the experiments, showing that it is possible to combine different theories into one model that can be used to predict the mass transport.Four barrier coatings: polyethylene, ethylene vinyl alcohol + kaolin, latex + kaolin and starch were evaluated using the parameters of greenhouse gas emissions and product costs. After the production of the barrier material, the coating process and the end-of-life handling scenarios were analysed, it emerged that starch had the lowest environmental impact and latex + kaolin had the highest.
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| 14. |
- Mastantuoni, Gabriella G.
(författare)
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Engineering of lignin in wood towards functional materials
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Through 270 million years of evolution, the finely tuned hierarchical structure of wood has been optimized for efficient nutrient transport and exceptional mechanical stability. Its distinctive orthotropic constitution can provide inspiration and design opportunities for the development of novel functional materials. In recent years, top-down modification approaches have adapted the wood structure for innovative applications, utilizing the hierarchical arrangement at different length scales. In doing so, preserving the structural integrity is of the essence.This thesis explores new top-down modification techniques for the functionalization and structural control of wood-based materials. With the intent of better preserving and utilizing the natural wood organization and native components, two different modification routes were explored on softwood Scots pine: complete lignin removal and in-situ lignin modification. Complete delignification was achieved through preventive crosslinking of the polysaccharide matrix, enhancing intercellular adhesion between tracheids and preventing the disintegration of the cellular arrangement after lignin removal. The second approach focused on chemical modification of lignin by sulfonation as an alternative to complete lignin removal, resulting in wood templates of high negative charge up to 375 µmol g-1 and with well-preserved residual lignin. Hot compression of the delignified wood veneers produced thin wood films with high optical transmittance of 71 % alongside exceptional tensile strength of 449 MPa and Young’s modulus of 50 GPa. Densification of lignin-retaining wood veneers yielded strong and transparent thin films with UV blocking ability. Additionally, these densified films could be easily recycled into discrete wood fibers. The integration of conductive polymers including poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and polypyrrole in in-situ sulfonated wood resulted in bio-composites with high conductivity up to 203 S m-1 and high pseudo-capacitance up to 38 mF cm-2, indicating that tailoring the wood chemistry and activating the redox activity of lignin by sulfonation are important strategies for the fabrication of composites with potential for sustainable energy applications. By tailoring both wood chemistry and morphology, a wood foam with unique microstructure, enhanced permeability, along with high ultimate strength of 9 MPa and Young’s modulus of 364 MPa was obtained. When combined with the conductive polymer PEDOT:PSS, the composite demonstrated uniform conductivity of 215 S m-1 and mechanoresponsive electrical resistance, showing promise in sensing and mechanoresponsive devices.Therefore, in-situ engineering of lignin proved to be a versatile toolkit to obtain wood templates of improved permeability and porosity, greater compliance to densification, and enhanced compatibility with conductive polymers.
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| 15. |
- Menzel, Carolin, et al.
(författare)
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Molecular structure of citric acid cross-linked starch films
- 2013
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Ingår i: Carbohydrate Polymers. - Amsterdam : Elsevier. - 0144-8617 .- 1879-1344. ; 96:2, s. 270-276
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Tidskriftsartikel (refereegranskat)abstract
- The effect of citric acid (CA) on starch films has been examined. A new method to detect cross-linkingof starch by CA in solution-cast films by molecular weight measurements is described. Furthermore, wemanaged to distinguished between free, mono- and di-esterified CA and quantify di-ester content withinstarch films by using a modification in the method of complexometric titration with copper(II)-sulfate.Cross-linking of starch by CA occurred at low temperature, 70◦C, which we assumed is so far the lowesttemperature reported where cross-linking reaction occurred. This is essential for starch coating applica-tions within paper industry since no high temperatures for curing will be required. However, curing at150◦C and high CA concentrations, 30 pph, increased cross-linking reaction. Furthermore, the physicalproperties like water solubility, gel content and glass transition temperature, were highly reflected bychanges in the molecular structure i.e. cross-linking and hydrolysis, as well as CA content and curingtemperature.
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| 16. |
- Kothapalli, Satya V.V.N. 1985-
(författare)
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Nano-Engineered Contrast Agents : Toward Multimodal Imaging and Acoustophoresis
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diagnostic ultrasound (US) is safer, quicker and cheaper than other diagnostic imaging modalities. Over the past two decades, the applications of US imaging has been widened due to the development of injectable, compressible and encapsulated microbubbles (MBs) that provide an opportunity to improve conventional echocardiographic imaging, blood flow assessment and molecular imaging. The encapsulating material is manufactured by different biocompatible materials such as proteins, lipids or polymers. In current research, researchers modify the encapsulated shell with the help of advanced molecular chemistry techniques to load them with dyes (for fluorescent imaging), nanoparticles and radioisotopes (for multimodal imaging) or functional ligands or therapeutic gases (for local drug delivery). The echogenicity and the radial oscillation of MBs is the result of their compressibility, which undoubtedly varies with the encapsulated shell characteristics such as rigidity or elasticity.In this thesis, we present acoustic properties of novel type of polyvinyl alcohol (PVA)-shelled microbubble (PVA-MB) that was further modified with superparamagnetic iron oxide nanoparticles (SPIONs) to work as a dual-modal contrast agent for magnetic resonance (MR) imaging along with US imaging. Apparently, the shell modification changes their mechanical characteristics, which affects their acoustic properties. The overall objective of the thesis is to investigate the acoustic properties of modified and unmodified PVA-MBs at different ultrasound parameters.The acoustic and mechanical characterization of SPIONs modified PVA-MBs revealed that the acoustical response depends on the SPION inclusion strategy. However they retain the same structural characteristics after the modification. The modified MBs with SPIONs included on the surface of the PVA shell exhibit a soft-shelled behavior and produce a higher echogenicity than the MBs with the SPIONs inside the PVA shell. The fracturing mechanism of the unmodified PVA-MBs was identified to be different from the other fracturing mechanisms of conventional MBs. With the interaction of high-pressure bursts, the air gas core is squeezed out through small punctures in the PVA shell. During the fracturing, the PVA-MBs exhibit asymmetric (other modes) oscillations, resulting in sub- and ultra-harmonic generation. Exploiting the US imaging at the other modes of the oscillation of the PVA-MBs would provide an opportunity to visualize very low concentrations of (down to single) PVA-MBs. We further introduced the PVA-MBs along with particles mimicking red blood cells in an acoustic standing-wave field to observe the acoustic radiation force effect. We observed that the compressible PVA-MBs drawn toward pressure antinode while the solid blood phantoms moved toward the pressure node. This acoustic separation method (acoustophoresis) could be an efficient tool for studying the bioclearance of the PVA-MBs in the body, either by collecting blood samples (in-vitro) or by using the extracorporeal medical procedure (ex-vivo) at different organs.Overall, this work contributes significant feedback for chemists (to optimize the nanoparticle inclusion) and imaging groups (to develop new imaging sequences), and the positive findings pave new paths and provide triggers to engage in further research.
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| 17. |
- Töpel, Mats, et al.
(författare)
-
Verifiering av sterilisering i processen för materialåtervinning av plast
- 2024
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Den nationella plastkartläggningen visade att år 2017 användes över 813 miljoner engångsprodukter av plast inom hälso- och sjukvården i Sverige. Den största delen av detta avfall hanteras genom förbränning, och för att minska den miljöpåverkan detta leder till har ett antal initiativ tagits för att inkludera materialet i slutna kretslopp, där plasten används i samma applikation på nytt och där materialets höga kvalité kan behållas.För att kunna göra det på ett säkert sätt krävs dock att materialet kan steriliseras för att vara säkert att hantera. Detta projekt har haft som mål att ta fram en metod för att mäta den eventuella steriliseringsprocess som sker när plast återvinns i den så kallade regranuleringsprocessen. Denna process innebär att plasten mals ner och smälts vid omkring 200°C. Om denna process är effektiv för att sterilisera materialet behövs inget separat steriliseringssteg innan regranuleringen. Vi har i projektet tillsatt bakterien Bacillus atrophaeus, en organism som ofta används för verifiering av sterilisering, till regranuleringen av LDPE-plast.Vi har sedan utvärderat olika metoder för att extrahera DNA från det regranulerade materialet samt utvecklat en qPCR-metod för att kvantifiera antalet överlevande bakterier. På så sätt har vi försökt mäta den eventuella steriliseringen av det regranulerade plastmaterialet.Resultatet visar att det fortfarande finns svårigheter att frigöra DNA-molekylerna från plasten, och att detta steg även kan ha en negativ påverkan på DNA-kvalitén. qPCR-metoden kan detektera B. atrophaeus och visar i ett separat värmeexperiment på en förväntad steriliseringseffekt över tid.Denna effekt kunde dock inte reproduceras i de labbförsök som utfördes med extruder (en utrustning som används för att pressa smält plastgranulat till den profil som önskas). Ett antal möjliga förklaringar till detta, samt förslag till vidare forskning presenteras avslutningsvis i rapporten. Exempel på fortsatta forskningsfrågor som presenteras är; fördelning av bakterier i plastmassan, inneslutande av celler i plastmaterialet, steriliseringseffekt i extrudern samt metod för bestrykning av bioindikator.
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| 18. |
- Kharazmi, Parastou, 1977-
(författare)
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Monitoring the gelation time and curing process of a reinforced polyester lining-original data
- 2019
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Annan publikationabstract
- Polymer linings used in sewer rehabilitation technologies are expected to cure fast in order for the renewed line to return to the service quickly and with minimum disruption. This dataset includes the original data obtained from the thermal analyses of a reinforced polyester composite used as pipe lining, including studying gelation, enthalpy and curing process for a better understanding of the material's curing behaviour after application in the field.
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| 19. |
- Guo, Weijin, et al.
(författare)
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Immunoassays on thiol-ene synthetic paper generate a superior fluorescence signal
- 2020
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Ingår i: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 163
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Tidskriftsartikel (refereegranskat)abstract
- The fluorescence-based detection of biological complexes on solid substrates is widely used in microarrays and lateral flow tests. Here, we investigate thiol-ene micropillar scaffold sheets (“synthetic paper”) as the solid substrate in such assays. Compared to state-of-the-art glass and nitrocellulose substrates, assays on synthetic paper provide a stronger fluorescence signal, similar or better reproducibility, lower limit of detection (LOD), and the possibility of working with lower immunoreagent concentrations. Using synthetic paper, we detected the antibiotic enrofloxacin in whole milk with a LOD of 1.64 nM, which is on par or better than the values obtained with other common tests, and much lower than the maximum level allowed by European Union regulations. The significance of these results lays in that they indicate that synthetically-derived microstructured substrate materials have the potential to improve the performance of diagnostic assays.
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| 20. |
- Pardon, Gaspard, 1983-, et al.
(författare)
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Simultaneous replication of hydrophilic and superhydrophobic micropatterns through area-selective monomer self-assembly
- 2016
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Ingår i: Advanced Materials Interfaces. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 2196-7350. ; 3:17
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Tidskriftsartikel (refereegranskat)abstract
- The control and permanent modification of the surface properties of polymers is a critical enabler for many applications. Here, we demonstrate a strategy, which we call surface energy mimicking, for the spontaneous replication of micropatterns of surface energies ranging from hydrophilic to superhydrophobic from a mold to several replicas.We introduce surface energy mimicking, enabling spontaneous replication of micropatterns (2D and 2.5D) of different surface energies, and enabled by self-assembly of functional mimicking monomers within a polymer matrix. We demonstrate replication of surface energies ranging from hydrophilic to superhydrophobic, and self-assembly of picoliter-droplet arrays on replicated micropatterned arrays containing hydrophilic patches in a hydrophobic surface.
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| 21. |
- Wang, Ruifu, et al.
(författare)
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Morphology and Flow Behavior of Cellulose Nanofibers Dispersed in Glycols
- 2019
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 52:15, s. 5499-5509
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding the morphology and flow behavior of cellulose nanofibers (CNFs) dispersed in organic solvents can improve the process of fabricating new cellulose-based nanocomposites. In this study, jute-based 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-oxidized CNFs with two different charge densities (0.64 and 1.03 mmol/g) were dispersed in ethylene glycol (EG) and propylene glycol (PG) using the solvent exchange method. The morphology and dimensions of CNFs in dry and suspension states were characterized using transmission electron microscopy, atomic force microscopy, and small-angle X-ray scattering techniques. The results showed that the cross-sectional dimensions remained the same in different solvents. Rheological measurements revealed that CNF suspensions in water or glycol (EG and PG) behaved similar to typical polymer solutions with a solvent-independent overlap concentration corresponding to the crowding factor of about 14. Furthermore, a thixotropic behavior was found in the concentrated CNF/glycol systems as observed in typical CNF aqueous suspensions. The fact that TEMPO-oxidized CNFs can be well dispersed in organic solvents opens up new possibilities to improve the CNF–polymer matrix blending, where the use of a viscous solvent can delay the transition to turbulence in processing and improve the control of fiber orientation because of a slower Brownian diffusive motion.
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| 22. |
- Adamopoulos, Stergios, et al.
(författare)
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Acoustic properties of acetylated wood under different humid conditions and its relevance for musical instruments
- 2018
-
Ingår i: Proceedings of the 9th European Conference on Wood Modification 2018, Arnhem, The Netherlands. - The Netherlands : Practicum. ; , s. 236-243
-
Konferensbidrag (refereegranskat)abstract
- In musical instrument making, less expensive wood species and materials with good characteristics and acoustical properties can provide potentials to find alternatives to the traditional exotic wood species used today. Modified wood could be such a choice if shows similar sound characteristics to wood coming from endangered and expensive tropical species with problematic commercial availability. In musical instruments, the overall functionality depends on the contribution of wood to different material performance indexes like sound radiation coefficient (R), characteristic impedance (z) and acoustic conversion efficiency (ACE). In this study, the performance indexes were measured for acetylated beech, maple and radiata pine and compared with these obtained for the reference wood materials maple, mahogany, alder and ash. A non-destructive free-free flexural vibration test method was used at constant temperature (20oC) but in different humid conditions- dry (35% RH), standard (65% RH) and wet (85% RH). Dimensional changes in the different humid conditions were also taken in account. Acetylated wood showed lower EMC with higher dimensional stability at each humidity level as compared with the reference wood materials. These properties are considered important factors for making quality musical instruments. Based on the acoustical properties, acetylated wood materials, especially radiata pine, showed good potential for use for musical instruments where specific characteristics of sound are required. However, the other types of acetylated wood can also be used for specific musical instruments.
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| 23. |
- Christophliemk, Hanna, 1973-, et al.
(författare)
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Starch-poly(vinyl alcohol) barrier coatings for flexible packaging paper and their effects of phase interactions
- 2017
-
Ingår i: Progress in organic coatings. - : Elsevier. - 0300-9440 .- 1873-331X. ; 111, s. 13-22
-
Tidskriftsartikel (refereegranskat)abstract
- Starch and poly(vinyl alcohol) based barrier coatings for flexible packaging papers were studied. Both octenyl succinate modified and hydroxypropylated corn and potato starches were blended with regular and ethylene modified poly(vinyl alcohol) to increase the water vapor barrier properties and enhance the flexibility of the starch coatings, in order to accomplish superior barrier performance. Phase separation between starch and poly (vinyl alcohol) was studied in detail, both in the solution and in dry draw-down coatings on paper. The barrier performance of the coated paper was evaluated with respect to water vapor transmission rate. Conditions for the creation of a thin surface layer consisting of only one of the pure polymers were identified and discussed in terms of phase separation in solution migration of poly(vinyl alcohol) to the uppermost surface layer. The phase separation promoted low water vapor transmission rates also with a rather high fraction of starch in the coatings
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| 24. |
- Garemark, Jonas
(författare)
-
Integrated Cellulosic Wood Aerogel Structures
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Highly porous aerogels based on renewable materials that possess structural functionality are appealing for sustainable energy regulation and harvesting. Achieving structural anisotropy provides advantageous directional diffusion and mechanical strength, however, introduces great engineering challenges, such as complex, costly, and time-consuming processing. Direct use of wood, where nanocellulose is favorably orientated, offers the opportunity of forming low-cost, scalable, and eco-friendly aerogels.This thesis explores a new type of nanostructured wood material design by filling the empty wood space with cellulosic aerogel structures based on its intrinsic biopolymers. The structure control is achieved through selective reassembly of the cell wall nanocomponents by cell wall partial dissolution and regeneration. The resultant structures, named integrated wood aerogels, show a unique combination of high specific surface area and strength due to partial retention of the wood hierarchical structure and formation of mesoporous nanofibrillated networks occupying the lumen. Different chemical systems are investigated, including DMAc/LiCl, ionic liquid (IL), and aqueous NaOH, and the processing-structure-property relationships are investigated. DMAc/LiCl is successfully used as proof of concept for integrated wood aerogel formation, but moisture sensitivity and toxicity of the system hinder further development. The IL [MTBD][MMP] is developed to solve the issues and to improve the structure control in cell wall dissolution and regeneration. An aqueous NaOH system advances the integrated cellulosic wood aerogel preparation further, considering low cost and greener chemistry. Wood composition, lignin in particular, is critical to the processing and final properties of the integrated wood aerogel. The influence of lignin content is investigated based on IL and NaOH systems. The influence of processing (such as chemical system, time and temperature) on the structure and properties (e.g. porosity, specific surface area, mechanical performance, thermal conductivity and charge density) of the aerogels are studied. Ascribing to the structure-property profile, the application of the integrated aerogel for efficient thermal insulation is demonstrated. Inspired by the water uptake in plants, high-performing pH-responsive wood power generators are formed based on water evaporation-induced electricity. The integrated aerogel structure greatly increases the solid/liquid interphase while allowing excellent mass diffusion.The methodologies presented in this thesis for selective nanoscale reassembly of the wood cell wall pave the way for advanced wood nanostructure control. The integrated wood aerogel structure reported here provides a universal material platform for advanced material design, such as a self-sustaining wood power generator. The facile and scalable processing contribute toward sustainable high-performing bioaerogels which can compete with fossil-based materials.
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| 25. |
- Hosseinpourpia, Reza, 1983-, et al.
(författare)
-
Hydrophobic Formulations Based on Tall Oil Distillation Products for High-Density Fiberboards
- 2020
-
Ingår i: Materials. - : MDPI. - 1996-1944. ; 13:18, s. 1-13
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigates the effect of renewable formulations based on tall oil bio-refinery products on the water vapor sorption and interfiber strength of cellulosic fibers as well as on the properties of high-density fiberboard (HDF) panels. The results obtained for HDF prepared using renewable formulations were compared to the results for HDF obtained using conventional synthetic paraffin wax (hydrowax), which is the hydrophobic agent currently utilized by the industry. Four tall oil distillation products (TODPs) with different levels of fatty and rosin acids were used for preparing the hydrophobic formulations with furfuryl alcohol as an organic solvent. According to determinations with an automated vapor sorption apparatus, the formulations had a similar effect with hydrowax on the sorption behavior of natural fibers. Unlike to hydrowax treatment, the ultimate tensile strength of cellulosic paper-sheets treated with the formulations remained unchanged or significantly increased. At the standard addition load of 1% (wt/wt dry fibers) of the formulations, HDF panels showed comparable and only in one case, e.g., TODP3-based formulation, slightly higher thickness swelling (24 h) than those with hydrowax. The best performing formulation (TODP2-based) in terms of tensile strength of paper sheets did not significantly change the mechanical properties of HDF panels in both standard climate and high humid conditions. Promising results at the standard and humid climate conditions were obtained for HDF panels manufactured with higher TODP2-based formulation amounts (3-5%) and reduced melamine-urea-formaldehyde resin content (10-12% instead of 14%, wt dry resin/wt dry fibers).
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| 26. |
- Hosseinpourpia, Reza, 1983-, et al.
(författare)
-
Properties of medium-density fibreboards bonded with dextrin-based wood adhesive
- 2019
-
Ingår i: Wood research. - : SDVÚ. - 1336-4561. ; 64:2, s. 185-194
-
Tidskriftsartikel (refereegranskat)abstract
- This study focuses on manufacturing of medium density fibreboard (MDF) panels bonded with dextrin-based wood adhesive and crosslinked in situ with various weight ratios of synthetic (e.g., polymeric-methane diphenyl-diisocyanate, pMDI) or bio-based (e.g., glyoxal) crosslinkers. The physical and mechanical properties of the panels were evaluated and compared with those from panels without crosslinker (control). Modulus of rupture (MOR) and internal bond (IB) strength of the MDF panels were considerably increased by increasing the crosslinkers’ content. While, slight improvements were observed in modulus of elasticity (MOE) of the panels as a function of crosslinker type and content. Addition of crosslinkers clearly reduced the thickness swelling (TS) and water absorption (WA) of the panels, whereas, the panels with pMDI showed superior performances than the control and glyoxal added ones within 4 h and 24 h immersion in water. The results indicate the potential of dextrin as wood panel adhesive along with the use of appropriate crosslinkers.
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| 27. |
- Jiang, Wen, et al.
(författare)
-
Liquefaction of lignocellulosic materials and its applications in wood adhesives — A review
- 2018
-
Ingår i: Industrial crops and products (Print). - : Elsevier. - 0926-6690 .- 1872-633X. ; 124, s. 325-342
-
Tidskriftsartikel (refereegranskat)abstract
- Liquefaction, a useful method of turning whole biomass into liquids, provides advantages for energy andpolymers and finds applications in many sectors. This paper reviews the different liquefaction technologies andrecent advances in the development of sustainable wood adhesives. Current liquefaction technologies includehydrothermal liquefaction (HTL) and moderate acid-catalyzed liquefaction (MACL). HTL produces bio-oils asprimary products, and solid residues and gases as by-products. MACL depends on the solvent types used, whichare grouped to polyhydric alcohols and phenols. Bio-polyols from alcohol liquefaction, phenolated biomass fromphenol liquefaction and phenolic compounds rich-HTL bio-oils have been used in the production of liquefiedbiomass-based adhesives, which have shown competitive properties but face challenges for industrial uses. Yet, abetter understanding of reaction pathways and optimization of the liquefaction processes is needed.
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| 28. |
- Montanari, Celine
(författare)
-
Transparent Wood Biocomposites for Sustainable Development
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sustainable wood nanotechnologies that combine optical transmittance and mechanical performance are interesting for new functionalities utilizing transparency. Wood is a sophisticated bio-based material with a natural hierarchical, anisotropic and porous structure. The wood cellular structure can be functionalized at the micro and nanostructural level for the design of advanced functional materials. In recent years, the development of transparent wood biocomposites derived from delignified wood substrates have gained interest because they combine attractive structural properties with optical functionality. Nanostructural tailoring of transparent wood biocomposites is required to improve optical transmittance, mechanical performance, and to add new functionalities. In this thesis, environmentally friendly material components and green chemical processes have been developed for the fabrication of nanostructurally tailored transparent wood biocomposites.Mesoporous delignified wood substrates with preserved microstructure and cellulose microfibril alignment in the cell wall are used as reinforcement in transparent wood biocomposites. Chemical functionalization strategies using renewable maleic, itaconic and succinic anhydrides have been explored for molecular and nanostructural tailoring of delignified cell walls. Cyclic anhydride functionalization results in high degree of esterification, reduces moisture content in the wood substrate, improves monomer diffusion within the cell wall, and further enables interface tailoring at the molecular scale with possibility for covalent attachment with polymer matrix. Transparent wood biocomposites were prepared by methyl methacrylate monomer impregnation followed by in situ polymerization within the chemically modified wood substrates. The anhydride-functionalized transparent wood biocomposites have improved wood-polymer interfacial interactions, resulting in improved optical and mechanical properties. Moreover, a bio-based polymer matrix was designed from renewable limonene oxide and acrylic acid for the fabrication of fully bio-based transparent wood biocomposites. The bio-based monomer can diffuse into the cell wall, and the polymer phase is both refractive index-matched and covalently linked to the wood substrate. The bio-based transparent wood biocomposites are nanostructured and demonstrate superior optical transmittance, low haze, and excellent mechanical performance.Nanostructural functionalization using phase-change materials is also demonstrated for the design of transparent wood biocomposites that combine thermal energy storage, tunable optical properties, and load bearing functions. Molecular and nanoscale interactions in transparent wood biocomposites are critical as they contribute to the favorable distribution of the phase-change material across the wood structure, which is a key component in optimizing thermal energy storage capacity. Bio-based design of transparent wood is also explored for thermal energy storage applications. Low environmental impact is achieved by combining the use of bio-based resources with green processing routes. Environmentally friendly transparent wood nanotechnologies can compete with petroleum-based plastics in applications such as load-bearing transparent panel and energy saving.
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| 29. |
- Neitzel, Nicolas, et al.
(författare)
-
Chemical composition, particle geometry, and micro-mechanical strength of barley husks, oat husks, and wheat bran as alternative raw materials for particleboards
- 2023
-
Ingår i: Materials Today Communications. - : Elsevier. - 2352-4928. ; 36
-
Tidskriftsartikel (refereegranskat)abstract
- Particleboards are used worldwide in various industry segments, like construction and furniture production. Nevertheless, increase in wood prices and logistical challenges urge the particleboard industry to find alternative raw materials. By-products and residues from the agricultural and food industries could offer possibilities for material sourcing at a local level. This study aimed to investigate the chemical composition, particle geometry, anatomical structure, and microtensile characteristics of such material, specifically barley husks (BH), oat husks (OH), and wheat bran (WB). Barley and oat husks were found to have comparable hemicelluloses and lignin contents to industrial wood chips but contained more ash. Wheat bran was rich in extractives and showed high buffering capacity. Light microscopy and microcomputed tomography revealed details of leaf structure for BH and OH as well as the multi-layer structure of WB. The ultimate microtensile strength of BH, various OH samples, and WB were respectively 2.77 GPa, 0.84-2.42 GPa, and 1.45 GPa. The results indicated that the studied materials could have potential uses as furnish materials in non-load bearing particleboards, where thermal or acoustic insulation properties are desirable.
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| 30. |
- Oliaei, Erfan, 1991-
(författare)
-
Lignocellulose Biocomposites– A Comparison of Wood Fibers and Microfibrillated Lignocellulose
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- All-lignocellulose composites, meaning densified fiber or fibril materials without added binder, show interesting mechanical properties and can be eco-friendly. Composites based on hot-pressed microfibrillated lignocellulose (MFLC) and lignocellulosic wood fiber (WF) reinforcements are compared with respect to processing, structure, mechanical properties, and eco-indicators. Also, these reinforcements are compared in hot-pressed degradable lignocellulosic crosslinked polycaprolactone (c-PCL) biocomposites based on in-situ polymerization of new caprolactone oligomers.The intermediate lignin content (≈11%) was favorable for MFLC preparation, although the cumulative energy demand was high for mechanical disintegration from unbleached softwood kraft pulp. The mechanical properties were much better for random-in-plane MFLC compared with WF composites due to lower porosity, better interfiber bonding, and smaller-scale defects. Data for strain-field development during tensile tests was in support of these findings. For c-PCL biocomposites, much higher ultimate strength was obtained for the c-PCL/MFLC composites compared with c-PCL/WF. The most important reason was the strainhardening behavior combined with higher strain to failure, since the scale of developing defects was much smaller with MFLC reinforcement.
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| 31. |
- Pallon, Love, 1984-
(författare)
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Polyethylene/metal oxide nanocomposites for electrical insulation in future HVDC-cables : probing properties from nano to macro
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nanocomposites of polyethylene and metal oxide nanoparticles have shown to be a feasible approachto the next generation of insulation in high voltage direct current cables. In order to reach an operationvoltage of 1 MV new insulation materials with reduced conductivity and increased breakdown strengthas compared to modern low-density polyethylene (LDPE) is needed.In this work polyethylene MgO nanocomposites for electrical insulation has been produced andcharacterized both from an electrical and material perspective. The MgO nanoparticles weresynthesized into polycrystalline nanoparticles with a large specific surface area (167 m2 g–1). Meltprocessing by extrusion resulted in evenly dispersed MgO nanoparticles in LDPE for the silane surfacemodified MgO as compared to the unmodified MgO. All systems showed a reduction in conductivityby up to two orders of magnitude at low loading levels (1–3 wt.%), but where the surface modifiedsystems were able to retain reduced conductivity even at loading levels of 9 wt.%. A maximuminteraction radius to influence the conductivity of the MgO nanoparticles was theoretically determinedto ca. 800 nm. The interaction radius was in turn experimentally observed around Al2O3 nanoparticlesembedded in LDPE using Intermodulation electrostatic force microscopy. By applying a voltage on theAFM-tip charge injection and extraction around the Al2O3 nanoparticles was observed, visualizing theexistence of additional localized energy states on, and around, the nanoparticles. Ptychography wasused to reveal nanometre features in 3D of electrical trees formed under DC-conditions. Thevisualization showed that the electrical tree grows by pre-step voids in front of the propagatingchannels, facilitating further growth, much in analogy to mechanical crack propagation (Griffithconcept). An electromechanical effect was attributed as possible mechanism for the formation of the voids.
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| 32. |
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| 33. |
- Ramamoorthy, Sunil Kumar, 1987-, et al.
(författare)
-
Performance of biocomposites from surface modified regenerated cellulose fibers and lactic acid thermoset bioresin
- 2015
-
Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X.
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of surface treatments, silane and alkali, on regenerated cellulose fibers was studied by using the treated fibers as reinforcement in lactic acid thermoset bioresin. The surface treatments were performed to improve the physico–chemical interactions at the fiber–matrix interface. Tensile, flexural and impact tests were used as indicator of the improvement of the interfacial strength. Furthermore, thermal conductivity, viscoelasticity measurements as well as microscopy images were made to characterize the fiber surface treatments and the effect on adhesion to the matrix. The results showed that silane treatment improved the mechanical properties of the composites as the silane molecule acts as link between the cellulose fiber and the resin (the fiber bonds with siloxane bridge while the resin bonds with organofunctional group of the bi-functional silane molecule) which gives molecular continuity in the interphase of the composite. Porosity volume decreased significantly on silane treatment due to improved interface and interlocking between fiber and matrix. Decrease in water absorption and increase in contact angle confirmed the change in the hydrophilicity of the composites. The storage modulus increased when the reinforcements were treated with silane whereas the damping intensity decreased for the same composites indicating a better adhesion between fiber and matrix on silane treatment. Thermogravimetric analysis indicated that the thermal stability of the reinforcement altered after treatments. The resin curing was followed using differential scanning calorimetry and the necessity for post-curing was recommended. Finite element analysis was used to predict the thermal behavior of the composites and a non-destructive resonance analysis was performed to ratify the modulus obtained from tensile testing. The changes were also seen on composites reinforced with alkali treated fiber. Microscopy images confirmed the good adhesion between the silane treated fibers and the resin at the interface.
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| 34. |
- Wojtasz, Joanna, et al.
(författare)
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Chemical pretreatment of wood chips : A comparative study of mild steam explosion and hot water extraction
- 2015
-
Ingår i: 6th Nordic Wood Biorefinery Conference, NWBC 2015. - : VTT Technical Research Centre of Finland. - 9789513883539 ; , s. 341-347
-
Konferensbidrag (refereegranskat)abstract
- Pretreatment of wood is a prerequisite for an efficient separation and utilization of its building blocks in future biorefinery concepts. Inherent recalcitrance of the cellulose-hemicellulose-lignin matrix of the cell wall poses huge challenges on separation of these components and implies usually a need for a broad set of methods targeting different components and providing as well chemical as morphological alterations. Mild steam explosion and hot water extraction are examples of typical pre-treatment methods enabling extraction of hemicelluloses and facilitating further processing of wood. Both are based on autohydrolysis of lignocellulosic material at high temperatures, but involve generally different conditions, the most prominent difference being a rapid disintegrating discharge employed in the steam explosion treatment, rendering morphological changes and altering structure accessibility compared to the physically less disruptive hot-water extraction. In this study we compare the key features of both of these methods and present that their effects on wood are somewhat non-uniform.
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| 35. |
- Corcoran, Angelica, 1988, et al.
(författare)
-
Comparing the structural development of sand and rock ilmenite during long-term exposure in a biomass fired 12 MWth CFB-boiler
- 2018
-
Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820. ; 171, s. 39-44
-
Tidskriftsartikel (refereegranskat)abstract
- Oxygen Carrier Aided Combustion (OCAC) is a novel combustion concept with the purpose to increase the overall efficiency in conventional circulating fluidized bed (CFB) boilers. By replacing the commonly used bed material with an oxygen carrier (OC), the conceptual idea is to utilize the fluid dynamics in a CFB and the inherent oxygen transport supported by the OC to increase the oxygen distribution within the furnace in time and space. The OCAC concept has been successfully validated and further reached long-term demonstration in full scale operation (75-MW th ). This work presents a first evaluation of how ilmenite particles are affected in regard to mechanical resistance during long-term exposure to OCAC conditions in Chalmers 12-MW th CFB-boiler. A sand and a rock ilmenite are evaluated with regard to their mechanical stability. For evaluation, samples of the fresh materials and samples collected during operation in the Chalmers boiler are investigated. The study shows that the two materials differ in how the mechanical degradation occurs with exposure time. The sand ilmenite form cavities which are held together by an ash layer before they are shattered into numerous pieces, whereas the rock ilmenite develops distinct cracks that cause splitting of the particles.
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| 36. |
- Jogi, Ramakrishna, et al.
(författare)
-
Understanding the formation of phenolic monomers during fractionation of birch wood under supercritical ethanol over iron based catalysts
- 2020
-
Ingår i: Journal of the Energy Institute. - : Elsevier. - 1743-9671 .- 1746-0220. ; 93:5, s. 2055-2062
-
Tidskriftsartikel (refereegranskat)abstract
- The liquefaction of biomass in ethanol, at the critical point, has high potential due to low temperature and pressure (243 °C, 63 bar) when compared with water (374 °C, 220 bar). The current study deals with the fractionation of birch wood powder which was liquefied under supercritical ethanol over acidic or non-acidic catalysts, 5 wt % Fe-Beta-H-150 and 5 wt % Fe–SiO2, respectively. Based on the results, the reaction mechanism for the formation of lignin degradation products was proposed. The main phenolic product was isoeugenol over 5 wt % Fe-Beta-H-150 while intermediate products, i.e. such as coniferyl, and sinapyl alcohol, 4-propenyl syringol, syringaresinol, as well as syringyldehyde reacted rapidly further. The thermodynamic analysis was performed by Joback approach and using Gibbs-Helmholtz equation supporting the obtained results.
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| 37. |
- Liu, Jun, et al.
(författare)
-
FShrinkage behaviour, early hydration and hardened properties of sodium silicate activated slag incorporated with gypsum and cement
- 2020
-
Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618. ; 248
-
Tidskriftsartikel (refereegranskat)abstract
- As a novel low carbon cementitious material, alkali-activated slag (AAS) attracted many researchers’ interests, not only because of its environmental benefits, but also some superior properties than Portland cement (PC). Due to different chemical reactions of AAS, gypsum, a commonly used expansive agent in PC, exhibits a different behaviour in AAS. This paper reports the investigation on the shrinkage behaviour of sodium silicate activated slag (SSAS) incorporated with gypsum and PC. In addition, the early properties, including setting time and early hydration products, were determined by Vicat apparatus, XRD and TG. The hardened properties, namely flexural and compressive strength, were investigated as well. The results showed that, by incorporating gypsum and PC, the drying shrinkage of SSAS could be significantly reduced because of the formation of expansive sulfate-rich and calcium-rich hydration products in terms of ettringite and Portlandite. The initial setting was delayed by blending PC, although adding gypsum accelerated the hydration of SSAS. The addition of gypsum and blend with 20% PC slightly increased flexural and compressive strengths of SSAS at 7 days and 28 days. © 2020 Elsevier Ltd
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| 38. |
- Maric, Jelena, 1983, et al.
(författare)
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Valorization of Automobile Shredder Residue Using Indirect Gasification
- 2018
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 32:12, s. 12795-12804
-
Tidskriftsartikel (refereegranskat)abstract
- Dual fluidized bed (DFB) gasification offers the possibility to convert solid fuels into a valuable gas, comprised of syngas, and hydrocarbons that can be readily handled in petrochemical units. DFB gasifiers are especially suitable for nonhomogeneous fuels, such as waste fractions. In this work, the possibility to use DFB gasification as a recycling/valorization method of automobile shredder residue is investigated. The gasification tests were carried out in the Chalmers 2–4 MWth gasifier over 4 days. The effects of ash on the gas and tar compositions, as well as on the activity of the bed inventory, were evaluated. The results show that 60% of the total carbon in the fuel can be recovered in the form of a permanent gas, whereby the produced gas contains 12%mol of C2–3 hydrocarbons. The tar levels measured in the produced gas were high, although it was clear that decomposition into monomer-like compounds occurred in the reactor, which resulted in the production of valuable petrochemical compounds, corresponding to 8–9% of the carbon in the feed. Using a higher operating temperature was found to be beneficial in terms of obtaining a higher gas yield, regardless of the level of ash enrichment in the system. The high ash levels in the fuel feed did not negatively affect the technical operation of the fluidized bed. Possible routes of carbon recovery are discussed.
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| 39. |
- Mukesh, Chandrakant, et al.
(författare)
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Production of C-14 Levulinate Ester from Glucose Fermentation Liquors Catalyzed by Acidic Ionic Liquids in a Solvent-Free Self-Biphasic System
- 2020
-
Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:10, s. 4828-4835
-
Tidskriftsartikel (refereegranskat)abstract
- Herein, we present the C-14 levulinate ester of 2,3-butanediol as the product of sugar fermentation liquors. The designed Brønsted acidic ionic liquid (BAIL) catalysts enable self-induced phase separation with ester products, and the role of anions has been investigated. Esterification reactions were carried out by 2,3-butanediol (2,3-BDO) and levulinic acid in solvent-free media and low temperatures (60–105 °C). For comparison, sulfuric acid, amberlite IR-120, and sulfonic acid-functionalized pyridinium ionic liquids with different anions were utilized as a catalyst upon esterification reaction. The diester product, namely, butane-2,3-diyl bis(4-oxopentanoate), was formed with a good yield (85%) and selectivity (85%) after complete conversion of 2,3-BDO in 24 h at 80 °C. The low yield (8%) of the monoester was observed. The monoester and diester were separated by a liquid–liquid extraction method. The ester products were characterized by various instrumental techniques such as 1H and 13C NMR, GC–FID, LC–MS, and FT-IR spectroscopy. The Hammett acidity functions of BAILs were determined from UV–vis spectroscopy. The catalyst was successfully recycled and reused in the processes. The spent BAILs were reused in six consecutive cycles with only a ∼7% diminished diester yield and selectivity. The produced levulinate ester will be useful as biofuel additives, solvents, plasticizers, and other applications.
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| 40. |
- Wang, Kai, et al.
(författare)
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A one-carbon chemicals conversion strategy to produce precursor of biofuels with Saccharomyces cerevisiae
- 2023
-
Ingår i: Renewable Energy. - : Elsevier BV. - 0960-1481 .- 1879-0682. ; 208, s. 331-340
-
Tidskriftsartikel (refereegranskat)abstract
- Utilization of one-carbon chemicals such as CO2, formate, and methanol by microorganisms can enable the sustainable production of fuels and chemicals. However, the low conversion efficiency of these chemicals by microorganisms is a major challenge. To address this, we designed a one-carbon strategy that can utilize CO2 and its derivative formate. Here, a platform yeast strain with improved formate utilization and NAD(P)H production was constructed and evaluated for its ability to produce free fatty acids (FFAs). Based on 13C-marked analysis, the one-carbon assimilation efficiency of the platform strain reached 11.24%. Through continuous optimization, under conditions of glucose feeding the formate utilization rate of the final strain reached 0.48 g/L/h, with the final titer of FFAs reached 10.1 g/L, which represented improvements of 21.8 times and 33.7 times, respectively. As such, the produced FFAs can be easily transformed into biodiesel by combining them with downstream technologies in future research.
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| 41. |
- Wu, Haizhou, 1987, et al.
(författare)
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Controlling hemoglobin-mediated lipid oxidation in herring (Clupea harengus) co-products via incubation or dipping in a recyclable antioxidant solution
- 2021
-
Ingår i: Food Control. - : Elsevier BV. - 0956-7135. ; 125
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Tidskriftsartikel (refereegranskat)abstract
- Applying value-adding techniques to fish co-products is rendered difficult due to their high susceptibility to hemoglobin (Hb)-mediated lipid oxidation. In this study, we investigated a dipping technology with a solution containing Duralox MANC 213- a mixture of rosemary extract, ascorbic acid, tocopherols and citric acid – to control lipid oxidation during storage at 0 °C and 20 °C. The possibilities to re-use the antioxidant solution was also analyzed, along with studies on the link between Duralox MANC and Hb-form. Dipping in Duralox MANC largely increased the oxidation lag phase; from <0.5 to >3.5 d at 20 °C, and from <1 d to >11 d at 0 °C. Even after re-use of the solution up to 10 times, lipid oxidation was completely inhibited at 0 °C. Duralox MANC could prevent auto-oxidation and hemin loss of herring Hb; which are suggested as the main mechanisms behind the observed stabilization of herring co-products against lipid oxidation.
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| 42. |
- Yahia, Mohamed, et al.
(författare)
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Effect of incorporating different ZIF-8 crystal sizes in the polymer of intrinsic microporosity, PIM-1, for CO2/CH4 separation
- 2021
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Ingår i: Microporous and Mesoporous Materials. - : Elsevier. - 1387-1811 .- 1873-3093. ; 312
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Tidskriftsartikel (refereegranskat)abstract
- Effective and economical carbon dioxide-methane separation (CO2/CH4) is highly desirable in several industries such as sweetening natural gases and renewable natural gas (RNG) from biogas and landfills. Among the different separation technologies, membrane separation has been shown to have lower cost of production and lower CH4 losses. In this study, Zeolitic Imidazole Frameworks (ZIF-8) crystals with sizes varying from 45 nm to 450 nm were synthesized and incorporated in the polymer of intrinsic microporosity, PIM-1, to form mixed matrix membranes (MMMs). The structure, morphology, and physicochemical properties of the MMMs were characterized by 1H NMR, FTIR, XRD, TGA, and SEM. ZIF-8 crystal size was controlled using the concentration of sodium formate. The influence of the ZIF-8 crystal size on MMMs was studied by sorption, gas permeability, and aging of the membranes. The MMMs with ZIF-8 crystals of 120 nm particle diameter yielded the greatest improvement in gas transport properties; the CO2/CH4 selectivity-CO2 permeability was 11.4 and 9700 Barrer compared to PIM-1 with 6.4 and 9300 Barrer respectively. The former is near the Robeson 2008 upper bound, while PIM-1 is on the 1991 upper bound. After 40 days of aging, selectivity increased and permeability decreased; the changes were parallel to the Robeson upper bounds indicating increased polymer packing and diffusivity selectivity.
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| 43. |
- Kharazmi, Parastou, 1977-
(författare)
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Durability study of reinforced polyester composite used as pipe lining under artificial aging conditions
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Tidskriftsartikel (refereegranskat)abstract
- The aging of sewer infrastructure is an ongoing problem. As a result, different materials and methods are being used in alternative sewer rehabilitation approaches. This work was conducted to study one pipe lining, namely the reinforced polyester composite, under artificial aging; this was done to provide a better understanding of the material’s performance under operating conditions, where it is regularly exposed to degrading factors such as heat and water. Aging of the material was monitored by means of several tests, including thermal and mechanical analyses, water absorption and microscopy. The results showed that the combination of aging in water and at high temperatures resulted in greater effects on the material compared to aging at high temperatures in dry conditions. Although the measured properties were affected significantly when immersed in water at high temperatures, the material showed acceptable properties at lower exposure temperatures close to the expected temperature inside sewer systems.
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| 44. |
- Kharazmi, Parastou, 1977-
(författare)
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Evaluation of Innovative Rehabilitation Technologies Utilising Polymer Composites for Aging Sewer Systems
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Water and wastewater sewer system maintenance is among the costliest aspects of infrastructure investment. The replacement of deteriorated lines is a difficult and expensive process that causes community disturbance and is generally not conducted fast enough to meet demand. To keep up with the rate of deterioration, the use of alternative rehabilitation technologies using polymer linings has increased significantly in recent years, both within Sweden and worldwide. Compared to the traditional pipe replacement method, these technologies are cost-effective, create less community disturbance, and offer a quick return to the service for the line. The main function of polymeric lining is to stabilise the condition of the pipeline, eliminate deterioration, and thereby extend the pipeline’s service life. Although rehabilitation technologies employing polymeric systems have been in use for over 30 years, there have been few technical assessments of either these technologies or the materials involved. Data gathered through the evaluation of these innovative technologies can make their benefits and limitations more widely understood, and can also be used to increase the effectiveness of the rehabilitation process in future.The main objective of this work was to contribute to an improved understanding of the most commonly used materials and methods employed in rehabilitation of wastewater and other applicable sewer lines in residential buildings in Sweden. The primary objective was not to prove that the emerging rehabilitation technologies work, but rather to increase knowledge of their weaknesses and strengths, identify any issues, and provide a technical assessment to support realistic expectations of pipeline rehabilitation. Gathering technical information in this way will help with the planning of future investigations; moreover, collecting extensive data will help to increase the effectiveness of the renewal works, aid progress in the field, and improve predictions regarding longevity and service life. As pipeline rehabilitation is still considered novel, and owing to the general lack of available data on the subject, a multi-approach study was carried out: this included evaluation of the polymeric materials’ performance in the presence of deteriorative factors, assessing the in-service state of the materials and lined sewers previously installed, monitoring the level of quality control implemented during previous rehabilitation works, and evaluating the environmental impacts of using pipe-lining technologies compared to pipe replacement. The techniques discussed included rehabilitation with epoxy and polyester resin-based lining materials, applied with brush-on and spray-on techniques, and cured-in-place pipe lining (installed by sending a resin-impregnated flexible tube inside the host pipe). Degradation of the resin-based lining materials was investigated via artificial aging involving immersion in water at elevated temperatures. The changes in materials that occurred during accelerated laboratory aging were tracked by means of various tests, including thermal and mechanical analyses, water absorption measurements and microscopy. The analysis focused on reinforced polyester-based and toughened epoxy-based lining materials in order to gain a better understanding of their performance as pipe lining. Moreover, the previously installed lined pipes and lining materials were also studied during laboratory examinations to evaluate the in-service performance of the materials and techniques under operating conditions over time, as well as to identify common defects. The state of the materials and the lined pipe were studied by means of different investigative methods, including visual inspection, microscopy, Fourier transform infrared spectroscopy, thickness measurement, thermal and mechanical analyses. This PhD work also includes an investigation to determine the level of quality control carried during some previous rehabilitation works. Data on the quality evaluation of previous rehabilitation works were gathered during visits to the work sites, as well as by analysing lined pipes that had already been installed. Finally, a comparative life-cycle assessment was undertaken to compare the environmental impacts of pipe replacement with those of alternative innovative rehabilitations, such as CIPP and coatings with polyester and epoxy polymeric systems. Data obtained from an LCA tool were used to facilitate comparison from an environmental perspective.Results from artificial aging in the lab indicated that the properties of polymeric lining materials changed significantly when high temperatures were combined with water exposure. However, the aging testing conducted for this study also found that the materials performed relatively well at temperatures close to the average temperatures inside sewerage systems. The results revealed that the polyester-based lining material was less sensitive when compared with epoxy-based lining materials during stimulated aging. Moreover, results from the in-service field demonstration (involving examination of 12 samples with up to 10 years of service, including reinforced polyester and modified epoxy linings or cured-in-place pipe (CIPP) lining) showed minimal evidence that the materials underwent significant deterioration after installation; instead, a majority of the common defects were found to be related to poor-quality installation practices. Because very few field samples were available to study, conclusions regarding overall performance could not be drawn. However, there is no evidence that these materials will not perform as expected during their service life when properly installed.Evaluating quality control of previous rehabilitation work revealed a gap between theory and practice where the level of quality control and documentation was concerned; furthermore, it also emerged that quality control and documentation is crucial to both the prevention of common issues and the overall effectiveness of the rehabilitation. Accordingly, a series of recommendations regarding the development of comprehensive quality control and quality assurance procedures (QC/QA) are provided in this work. These recommendations highlight the aspects that are most important to consider at each of several key stages (before installation, during installation, and after rehabilitation work is completed).Results from comparative life-cycle assessment (LCA) showed that alternative technologies, including cured-in-place (flexible sleeve) and coating techniques, have some advantages over pipe replacement from an environmental perspective. However, the choice to use one rehabilitation technology over another is a multi-stage decision-making process that should not be based solely on a single factor.This PhD work promotes an improved understanding of the limitations and benefits of polymeric lining through the testing performed and analyses conducted. This work highlights the need for improved quality control, and further suggests that developing a detailed and comprehensive quality control plan for each technology would provide higher and more consistent quality overall. The study also demonstrates that the long-term strength of any rehabilitation work depends on various factors, and that selecting one method over another must be a process based on extensive knowledge and understanding of each rehabilitation technology. No evidence was found to indicate that the materials could not perform well under working conditions if selected and installed appropriately. However, a larger number of field samples with longer in-service time and a more detailed technical history, along with a more extended experimental plan for laboratory investigations based on the results of this PhD work, will allow for the gathering of the data required to answer questions regarding life expectancy with a higher degree of certainty.
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| 45. |
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| 46. |
- Ghavidel, Amir, et al.
(författare)
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Comparison of chemical compositions in wood and bark of Persian silk tree (Albizia julibrissin Durazz)
- 2022
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Ingår i: Wood Material Science & Engineering. - : Taylor & Francis. - 1748-0272 .- 1748-0280. ; 17:6, s. 759-770
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Tidskriftsartikel (refereegranskat)abstract
- This research was conducted to identify and compare the chemical compositions in Persian silk tree(Albizia julibrissin Durazz.) from different parts of wood and bark, using Fourier Transform Infrared(FTIR) Spectroscopy, gas and liquid chromatography coupled to mass spectrometry (GC-MS, LCMS),and elemental analysis. FTIR analysis showed significant differences in the chemical structureof bark and wood at peaks that belong to the cellulose and hemicelluloses. According to theresults, the C-O-C asymmetric stretch vibration in cellulose and hemicelluloses peak of Persian silktree was lower in the bark and ѵC=O in quinone or p-quinone peak was higher in the bark. Theresults of GC-MS showed 12 chemical constituents in the bark and 43 in the wood, respectively.Among these, hexadecanoic acid and inositol were in common. According to the LC-MS analyses,bark samples were rich in lignan compositions and triterpenoid saponins, whereas wood was poorin these compositions. Altogether 61 compositions have been tentatively identified and describedfrom bark and wood tissues; many of them were identified for the first time. Energy-dispersive Xray(EDX) spectrometry illustrated that the bark contained iron and aluminium, sodium,phosphorus, sulphur and chlorine, while these elements did not exist in wood.
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| 47. |
- Vastesson, Alexander, et al.
(författare)
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Polymer Nanoliter Well Arrays for Liquid Storage and Rapid On-demand Electrochemical Release
- 2018
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 267, s. 111-118
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Tidskriftsartikel (refereegranskat)abstract
- Polymer microfluidic systems are of increasing importance in several applications in biomedicine and biosensing. The integrated encapsulation, storage, and controlled release of small amounts of liquid in such systems remains an unresolved technical challenge. Here, we report two methods for the room-temperature and adhesive-free sealing of 1–330 nanoliter volumes of liquid in off-stoichiometry thiol-ene polymer well arrays by spontaneous bonding to 200 nm thin gold films. Sealed well arrays were stored for more than one month in a liquid environment with <10% liquid loss, and for more than one week in air with minimal loss. We demonstrated that controlling the electrical potential and polarity over encapsulated wells allowed for selecting one of two well opening mechanisms: slow anodic electrochemical etching, or rapid electrolytic gas pressure-induced bursting of the gold film. The results may find potential applications in diagnostic testing, in vivo drug delivery, or in spatio-temporal release of chemical compounds in biological assays.
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| 48. |
- Guo, Weijin, 1989-
(författare)
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Synthetic Paper for Point-of-Care Diagnostics : Capillary control, surface modifications, and their applications
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Capillary-based platforms for diagnostics are popular for the point-of-care diagnostics market because of their low cost, easy fabrication, and easy operation. Lateral flow tests are an excellent example of capillary-based platforms for point-of-care diagnostics. However, most current lateral flow tests can only provide qualitative results or have low sensitivity. Lateral flow tests with better performance are needed. In this thesis, I tried to improve the performance of lateral flow tests from different aspects: flow rate control, surface modification, plasma separation, and immunoassay application.Variations in sample liquid properties (viscosity and surface energy) can lead to variations in the flow rate, and therefore variations in the lateral flow test results. I developed a novel capillary pump system that can provide a constant pumping flow rate independent of liquid surface energy and viscosity. This capillary pump system works well for bodily liquids, even for blood, which has low surface energy. This capillary pump system can provide a flow rate 20.96-24.76 μL/min for all the kinds of liquid tested, which is relevant for LFTs in clinical diagnostics.The substrate of lateral flow tests should be hydrophilic and must be easy to functionalize with protein for immunoassay applications. I developed surface modification protocols for the novel lateral flow test substrate - OSTE synthetic paper. I tested different hydrophilic treatments of synthetic paper, including PEGMA, HEMA, O2 plasma, and Tween 20 coating. All these treatment methods work well, and they provide slightly different hydrophilicity, and therefore different pumping velocities for liquid samples. They can be used for applications with different requirements on hydrophilicity. Moreover, I flowed blood plasma samples through the synthetic paper with different hydrophilic treatments and found that the OSTE synthetic paper surface retains low amounts of plasma protein (with a protein recovery rate close to 100%), which shows that synthetic paper is a good material for biological sample handling. I also developed and validated two protocols for grafting on synthetic paper: thiol-yne-biotin-streptavidin and thiol-maleimide-biotin-streptavidin.Plasma separation is an essential step for lateral flow tests using whole blood as the sample. Usually, commercial filtration membranes for plasma separation are added to the test strips. Such membranes, however, suffer from a protein retention. I built a plasma extractor using synthetic paper. The synthetic paper underwent hydrophilic treatment and was precoated with agglutination antibody. The agglutination antibody caused local agglutination of red blood cells, while the plasma continued pumping using capillary action, thus achieving the separation. The synthetic paper had a smaller surface area to make sure less protein is retained by the surface, resulting in a higher protein recovery rate (>82%) than commercial filtration membranes (73%).Microarray technology provides a high-throughput method to test the functionality of LFT immunoassay reagents. Nitrocellulose and glass are traditional materials for microarray platforms. I used them and synthetic paper as the substrate for a protein microarray platform, and made a systematic comparison of these three substrates with respect to the fluorescence signal. To accomplish this, I used an indirect competitive sandwich assay for the detection of the antibiotic enrofloxacin in whole milk, and fluorophore as the signal label. The experiments showed that synthetic paper could provide an overall better performance in terms of signal variance, reproducibility, limit of detection, and goodness of fit. I further investigated the influence of synthetic paper geometry design on the assay performance and chose the best design for matrix study of milk. I found the matrix effect of milk to be low, and that synthetic paper can be used for enrofloxacin detection in whole milk. The LOD of enrofloxacin detection in whole milk is 1.64 nM, which is much lower than the concentration (288.98 nM) stipulated by EU regulations.The results of the microarray platform can provide guidelines for designing lateral flow tests using synthetic paper as the substrate.These contributions can be combined or used individually to improve the performance of lateral flow tests on reproducibility and/or sensitivity. Synthetic paper has been proved to be a good substrate for LFTs by allowing easy sample handling and immunoassay coupling, and will find wider applications in the field of quantitative LFTs.
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| 49. |
- Ghaffari, Roujin, 1994, et al.
(författare)
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Effect of alkalinity on the diffusion of solvent-fractionated lignin through cellulose membranes
- 2023
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Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 30:6, s. 3685-3698
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Tidskriftsartikel (refereegranskat)abstract
- Mass transport of liberated lignin fragments from pits and fiber walls into black liquor is considered a determining step in the delignification process. However, our current understanding of the diffusion of lignin through cellulose and the influential parameter on this process is very limited. A comprehensive and detailed study of lignin mass transport through cellulosic materials is, therefore, of great importance. In this study, diffusion cell methodology is implemented to systematically investigate the transport of fractionated kraft lignin molecules through model cellulose membranes. Pulping is a complex process and lignin is very heterogenous material therefore to perform a more detailed study on lignin diffusion, we included an additional solvent fractionation step. One of the benefits of this method is that the setup can be adjusted to various experimental conditions allowing the complex chemical reactions occurring during pulping, which would affect the mass transfer of lignin, to be avoided. Here, the effects of the alkalinity of the aqueous solution and molecular weight of the kraft lignin molecules on their diffusion were investigated. Additionally, NMR spectroscopy, size exclusion chromatography, and UV/Vis spectroscopy were used to characterize the starting material and the molecules that passed through the membrane. Lignin molecules detected in the acceptor chamber of the diffusion cells had lower molecular weights, indicating a size fractionation between the donor and acceptor chamber. UV/Vis showed higher concentrations of ionized conjugated kraft lignin molecules in the acceptor chamber, which is a sign of chemical fractionation. This study suggests that the diffusion of lignin through small cellulose pores can be enhanced by decreasing the average molecular weight of the diffusing kraft lignin molecules and increasing alkalinity.
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| 50. |
- Pietiäinen, Solja, et al.
(författare)
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Effect of physicochemical properties, pre-processing, and extraction on the functionality of wheat bran arabinoxylans in breadmaking – A review
- 2022
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Ingår i: Food Chemistry. - : Elsevier BV. - 0308-8146 .- 1873-7072. ; 383
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Forskningsöversikt (refereegranskat)abstract
- Arabinoxylan (AX) is an abundant hemicellulose in wheat bran and an important functional component in bakery products. This review compares preprocessing and extraction methods, and evaluates their effect on AX properties and functionality as a bread ingredient. The extraction process results in AX isolates or concentrates with varying molecular characteristics, indicating that the process can be adjusted to produce AX with targeted functionality. AX functionality in bread seems to depend on AX properties but also on AX addition level and interactions with other components. This review suggests that the use of AX with tailored properties together with properly optimized baking process could help increasing the amount of added fiber in bread while maintaining or even improving bread quality.
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