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Sökning: WFRF:(Mathew Aji P.)

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1.
  • Deepalakshmi, P, et al. (författare)
  • Advances in elastomers : Their composites and nanocomposites: State of art, new challenges and opportunities
  • 2013
  • Ingår i: Advances in elastomers II. - Berlin : Encyclopedia of Global Archaeology/Springer Verlag. - 9783642209277 - 9783642209284 ; , s. 1-9
  • Bokkapitel (refereegranskat)abstract
    • The field of elastomers, their composites and nanocomposites has gained a lot of interest in recent years. These composite materials have great significance both from the fundamental and application point of view. Since this field is growing at a faster rate, it is always necessary to address the structure, properties and applicability of such materials. The present chapter gives a brief account on various elastomer systems, their composites and nanocomposites. Various topics such as elastomer based macrocomposites, nanocomposites, interphase modification, compatiblisation of rubber based nanocomposites, fully green elastomer nanocomposites, elastomeric micro and nanocomposites for tyre applications, elastomer based bionanocomposites, bio-medical applications of elastomeric composites and nanocomposites have been very briefly discussed. Finally the applications, new challenges and opportunities of these composites and nanocomposites are also discussed.
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2.
  • Samyn, P., et al. (författare)
  • Plasma deposition of polymer composite films incorporating nanocellulose whiskers
  • 2011
  • Ingår i: European Physical Journal. - : EDP Sciences. - 1286-0042 .- 1286-0050. ; 56:2
  • Tidskriftsartikel (refereegranskat)abstract
    • In a trend for sustainable engineering and functionalization of surfaces, we explore the possibilities of gas phase processes to deposit nanocomposite films. From an analysis of pulsed plasma polymerization of maleic anhydride in the presence of nanocellulose whiskers, it seems that thin nanocomposite films can be deposited with various patterns. By specifically modifying plasma parameters such as total power, duty cycle, and monomer gas pressure, the nanocellulose whiskers are either incorporated into a buckled polymer film or single nanocellulose whiskers are deposited on top of a polymeric film. The density of the latter can be controlled by modifying the exact positioning of the substrate in the reactor. The resulting morphologies are evaluated by optical microscopy, AFM, contact angle measurements and ellipsometry.
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3.
  • Ninan, Neethu, et al. (författare)
  • Plasma assisted design of biocompatible 3D printed PCL/silver nanoparticle scaffolds : in vitro and in vivo analyses
  • 2021
  • Ingår i: Materials Advances. - : Royal Society of Chemistry (RSC). - 2633-5409. ; 2:20, s. 6620-6630
  • Tidskriftsartikel (refereegranskat)abstract
    • 3D printing provides numerous opportunities for designing tissue engineering constructs with intricate porosity, geometry and favourable mechanical properties and has the potential to revolutionize medical treatments. However, an often-encountered restriction is the selection of materials suitable for utilization in 3D printing, not all of which have appropriate biocompatibility properties. In this work, fused deposition modeling was employed to fabricate 3D PCL constructs without the use of any solvent. Plasma deposition was used to modify the surface of the scaffolds, followed by immobilization of silver nanoparticles. The physico-chemical and mechanical analyses demonstrated that the scaffolds retained their porosity and mechanical integrity. The mechanical properties evaluated by the nanoindentation technique demonstrated an increase in reduced modulus to 1.87 +/- 0.012 GPa for PCL scaffolds functionalized with silver nanoparticles for 24 hours. We also showed complete prevention of colonization by medically relevant pathogens. The modified scaffolds had good biocompatibility. The immune response studies in the culture of macrophages confirmed a reduction in the level of expression of pro-inflammatory cytokines which is a key requirement for successful wound healing. The in vivo studies on Sprague Dawley rats indicated enhanced angiogenesis and the absence of foreign body reaction for scaffolds functionalized with silver nanoparticles for 6 hours. The 3D printing approach presented in this study provides new sustainable opportunities that can be adopted for designing biomaterial constructs with enhanced biological properties.
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4.
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5.
  • Valencia, Luis, et al. (författare)
  • Biobased Cellulose Nanofibril–Oil Composite Films for Active Edible Barriers
  • 2019
  • Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 11:17, s. 16040-16047
  • Tidskriftsartikel (refereegranskat)abstract
    • Low-concentration oil-in-water emulsions stabilized by cellulose nanofibrils (CNFs) extracted from primary plant cell wall materials are used to prepare thin biobased CNF–oil composite films by solvent casting. Flexible, transparent, and biodegradable composite films are obtained, with increased thermal stability (up to 300 °C) as the oil concentration increases. Examination of the microstructure demonstrates a clear dependency on the oil content, as a multilayered structure where the oil phase trapped between two layers of CNFs is appreciated at high oil concentrations. The embedded oil significantly influences the mechanical and wetting properties of the films, confirming their potential for use in packaging systems. Encapsulation of curcumin in the composite films leads to an increased antioxidant (up to 30% radical scavenging activity) and antimicrobial activity, inhibiting the growth of foodborne bacteria such as Escherichia coli. The resulting composite films show promising results in the field of active packaging for applications in the food, pharmaceutical, and cosmetic industries.
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6.
  • Valencia, Luis, et al. (författare)
  • Multivalent ion-induced re-entrant transition of carboxylated cellulose nanofibrils and its influence on nanomaterials' properties
  • 2020
  • Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 12:29, s. 15652-15662
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work, we identify and characterize a new intriguing capability of carboxylated cellulose nanofibrils that could be exploited to design smart nanomaterials with tuned response properties for specific applications. Cellulose nanofibrils undergo a multivalent counter-ion induced re-entrant behavior at a specific multivalent metal salt concentration. This effect is manifested as an abrupt increase in the strength of the hydrogel that returns upon a further increment of salt concentration. We systematically study this phenomenon using dynamic light scattering, small-angle X-ray scattering, and molecular dynamics simulations based on a reactive force field. We find that the transitions in the nanofibril microstructure are mainly because of the perturbing actions of multivalent metal ions that induce conformational changes of the nanocellulosic chains and thus new packing arrangements. These new aggregation states also cause changes in the thermal and mechanical properties as well as wettability of the resulting films, upon water evaporation. Our results provide guidelines for the fabrication of cellulose-based films with variable properties by the simple addition of multivalent ions.
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7.
  • Valencia, Luis, et al. (författare)
  • On the mineralization of nanocellulose to produce functional hybrid materials
  • 2022
  • Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 10:17, s. 9248-9276
  • Forskningsöversikt (refereegranskat)abstract
    • Nanocellulose (NC)-based materials constitute a new class of bio-based building blocks that are inspiring advances for the next generation of high-performance sustainable materials. However, NC exhibits important drawbacks which limit its applications, such as its inherent interaction with bacteria and proteins, low conductivity, poor thermal stability, high water absorption (leading to, among other things, loss of structural integrity), etc. An efficient strategy to improve this, besides the possibility of introducing further properties, is through mineralization by in situ growing inorganic subcomponents to form NC-based hybrids. Following the example of nature which has been mineralizing biopolymers from the beginning of life to create complex structures (forming protective shields or structural supports), mineralization can be adopted in different (2D/3D) configurations, for instance, membranes, scaffolds, sponges, and monoliths (as per requirements), by in situ growing multiple subcomponents such as metal oxides, silicates, and metal–organic frameworks. The components act synergistically complementing each other, thus providing new functionalities that the components individually do not possess. For instance, it is possible to introduce properties such as self-healing behavior, magnetic character, antimicrobial properties, electrical and thermal conductivity, etc., which opens a wide range of opportunities in a variety of fields (e.g., energy, printed electronics, biomedicine, water/gas purification, etc.) of current interest and requirements. The present review paper summarizes and discusses the advanced applications of thus-formed nanocellulose hybrids, along with a general overview of the synthesis protocol and advanced characterization tools used to analyze these complex materials.
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8.
  • Visakh, P. M., et al. (författare)
  • Cellulose nanofibres and cellulose nanowhiskers based natural rubber composites: Diffusion, sorption, and permeation of aromatic organic solvents
  • 2012
  • Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 124:2, s. 1614-1623
  • Tidskriftsartikel (refereegranskat)abstract
    • This article investigates the transport behavior of three aromatic organic solvents, viz. benzene, toluene, and p-xylene in natural rubber nanocomposite membranes containing cellulose nanofibres (CNFs) and cellulose nanowhiskers (CNWs) isolated from bamboo pulp. The solvent molecules act as molecular probes to study the diffusion, sorption, and permeation through the nanocomposites, and provide information on the nanocomposite structure and matrix-filler interactions. Both the nanocelluloses were found to decrease the uptake of aromatic solvents in nanocomposite membranes, but the effect was more significant in the case on nanofibers compared to nanowhiskers. Furthermore, the uptake decreased with increased penetrant size; being the highest for benzene and the lowest for p-xylene. Transport parameters such as diffusion coefficient, sorption coefficient, and permeation coefficient have been calculated. Comparison of the experimental values of equilibrium solvent uptake with the predicted values indicated that both the nanocelluloses have restricted the molecular mobility at the interphase and thereby decreased the transport of solvents through the materials; being more significant for nanofibers. The results showed that both the used cellulosic nanomaterials act as functional additives capable of manipulating and tailoring the transport of organic solvents through elastomeric membranes, even at concentrations as low as 2.5 wt %.
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9.
  • Visakh, P. M., et al. (författare)
  • Crosslinked natural rubber nanocomposites reinforced with cellulose whiskers isolated from bamboo waste: Processing and mechanical/thermal properties
  • 2012
  • Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier BV. - 1359-835X .- 1878-5840. ; 43:4, s. 735-741
  • Tidskriftsartikel (refereegranskat)abstract
    • Crosslinked natural rubber (NR) nanocomposites were prepared using cellulose nanowhiskers (CNWs) that were extracted from bamboo pulp residue of newspaper production, as the reinforcing phase. The coagulated NR latex containing bamboo nanowhiskers (master batch) was compounded with solid NR and vulcanizing agents using a two-roll mill and subsequently cured to introduce crosslinks in the NR phase. No evidence of micro-scaled aggregates of cellulose nanowhiskers in NR matrix was observed in scanning electron microscopy (SEM) images. The addition of CNWs had a positive impact on the tensile strength, E-modulus, storage modulus, tan delta peak position and thermal stability of the crosslinked NR. Theoretical modeling of the mechanical properties showed a lower performance than predicated and therefore further process optimization and/or compatibilization are required to reach the maximum potential of these nanocomposites.
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10.
  • Visakh, P. M., et al. (författare)
  • Natural polymers : Their blends, composites and nanocomposites: State of art, new challenges and opportunities
  • 2013
  • Ingår i: Advances in Natural Polymers Composites and Nanocomposites. - Dordrecht : Encyclopedia of Global Archaeology/Springer Verlag. - 9783642209390 ; , s. 1-20
  • Bokkapitel (refereegranskat)abstract
    • The present chapter deals with a brief account on various types of natural polymers such as cellulose, chitin, starch, soy protein, casein, hemicellu-loses, alginates, polylactic acid and polyhydroxyalkanoates etc. Blends, composites and nanocomposites based on these polymers have been very briefly discussed. Finally the applications, new challenges and opportunities of these biomaterials are also discussed.
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11.
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12.
  • Abdelhamid, Hani Nasser, 1986-, et al. (författare)
  • 3D printing of cellulose/leaf-like zeolitic imidazolate frameworks (CelloZIF-L) for adsorption of carbon dioxide (CO2) and heavy metal ions
  • 2023
  • Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 52:10, s. 2988-2998
  • Tidskriftsartikel (refereegranskat)abstract
    • Metal–organic frameworks (MOFs) have advanced several technologies. However, it is difficult to market MOFs without processing them into a commercialized structure, causing an unnecessary delay in the material's use. Herein, three-dimensional (3D) printing of cellulose/leaf-like zeolitic imidazolate frameworks (ZIF-L), denoted as CelloZIF-L, is reported via direct ink writing (DIW, robocasting). Formulating CelloZIF-L into 3D objects can dramatically affect the material's properties and, consequently, its adsorption efficiency. The 3D printing process of CelloZIF-L is simple and can be applied via direct printing into a solution of calcium chloride. The synthesis procedure enables the formation of CelloZIF-L with a ZIF content of 84%. 3D printing enables the integration of macroscopic assembly with microscopic properties, i.e., the formation of the hierarchical structure of CelloZIF-L with different shapes, such as cubes and filaments, with 84% loading of ZIF-L. The materials adsorb carbon dioxide (CO2) and heavy metals. 3D CelloZIF-L exhibited a CO2 adsorption capacity of 0.64–1.15 mmol g−1 at 1 bar (0 °C). The materials showed Cu2+ adsorption capacities of 389.8 ± 14–554.8 ± 15 mg g−1. They displayed selectivities of 86.8%, 6.7%, 2.4%, 0.93%, 0.61%, and 0.19% toward Fe3+, Al3+, Co2+, Cu2+, Na+, and Ca2+, respectively. The simple 3D printing procedure and the high adsorption efficiencies reveal the promising potential of our materials for industrial applications.
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13.
  • Abdelhamid, Hani Nasser, 1986-, et al. (författare)
  • Binder-free Three-dimensional (3D) printing of Cellulose-ZIF8 (CelloZIF-8) for water treatment and carbon dioxide (CO2) adsorption
  • 2023
  • Ingår i: Chemical Engineering Journal. - 1385-8947 .- 1873-3212. ; 468
  • Tidskriftsartikel (refereegranskat)abstract
    • Metal-organic frameworks (MOFs) have advanced several applications, including energy, biomedical and envi-ronmental remediation. However, most of the reported MOF materials are in powder form limiting their ap-plications. This study reported the processing of MOF via three-dimensional (3D) printing of cellulose-MOFs (denoted as CelloMOFs). The 3D printing procedure involved a one-pot method including three steps: gel for-mation, 3D printing, and in-situ growth of MOF crystals. This procedure offered 3D printing of CelloMOF via a binder-free method with high loading of 67.5 wt%. The 3D-printed porous structures were used as adsorbents for carbon dioxide (CO2), dye, and heavy metal ions. They can be also used as catalysts for the degradation of water pollutants such as organic dyes. The materials can be separated easily without requiring extra procedures such as centrifugation or filtration. The materials offered complete (>99%) removal of organic dyes within 10 min with high selectivity toward anionic dyes e.g, methyl blue (MeB). The materials exhibited CO2 and heavy metal ions adsorption capacities of 0.63 mmol/g (27.7 mg/g) and 8-328 mg/g, respectively, with good recyclability. Our methodology will open new venues for advanced 3D printing of CelloMOF and its applications for water treatment and air purification.
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14.
  • Abdelhamid, Hani Nasser, et al. (författare)
  • CelloZIFPaper : Cellulose-ZIF hybrid paper for heavy metal removal and electrochemical sensing
  • 2022
  • Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 446
  • Tidskriftsartikel (refereegranskat)abstract
    • The processing of hierarchical porous zeolitic imidazolate frameworks (ZIF-8) into a cellulose paper using sheet former Rapid-Kothen (R.K.) is reported. The procedure is a promising route to overcome a significant bottleneck towards applying metal-organic frameworks (MOFs) in commercial products. ZIF-8 crystals were integrated into cellulose pulp (CP) or TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-oxidized cellulose nanofibrils (TOCNF) following an in-situ or ex-situ process; the materials were denoted as CelloZIFPaper_In Situ and CelloZIFPaper_Ex Situ, respectively. The materials were applied as adsorbents to remove heavy metals from water, with adsorption capacities of 66.2-354.0 mg/g. CelloZIFPaper can also be used as a stand-alone working electrode for the selective sensing of toxic heavy metals, for instance, lead ions (Pb2+), using electrochemical-based methods with a limit of detection (LOD) of 8 mu M. The electrochemical measurements may advance 'Lab-onCelloZIFPaper' technologies for label-free detection of heavy metal ions.
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15.
  • Abdelhamid, Hani Nasser, 1986-, et al. (författare)
  • Cellulose-Based Materials for Water Remediation : Adsorption, Catalysis, and Antifouling
  • 2021
  • Ingår i: Frontiers in Chemical Engineering. - : Frontiers Media SA. - 2673-2718. ; 3
  • Forskningsöversikt (refereegranskat)abstract
    • Cellulose-based materials have been advanced technologies that used in water remediation. They exhibit several advantages being the most abundant biopolymer in nature, high biocompatibility, and contain several functional groups. Cellulose can be prepared in several derivatives including nanomaterials such as cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidized cellulose nanofibrils (TOCNF). The presence of functional groups such as carboxylic and hydroxyls groups can be modified or grafted with organic moieties offering extra functional groups customizing for specific applications. These functional groups ensure the capability of cellulose biopolymers to be modified with nanoparticles such as metal-organic frameworks (MOFs), graphene oxide (GO), silver (Ag) nanoparticles, and zinc oxide (ZnO) nanoparticles. Thus, they can be applied for water remediation via removing water pollutants including heavy metal ions, organic dyes, drugs, and microbial species. Cellulose-based materials can be also used for removing microorganisms being active as membranes or antibacterial agents. They can proceed into various forms such as membranes, sheets, papers, foams, aerogels, and filters. This review summarized the applications of cellulose-based materials for water remediation via methods such as adsorption, catalysis, and antifouling. The high performance of cellulose-based materials as well as their simple processing methods ensure the high potential for water remediation. 
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16.
  • Abdelhamid, Hani Nasser, 1986-, et al. (författare)
  • Cellulose-Based Nanomaterials Advance Biomedicine : A Review
  • 2022
  • Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 23:10
  • Forskningsöversikt (refereegranskat)abstract
    • There are various biomaterials, but none fulfills all requirements. Cellulose biopolymers have advanced biomedicine to satisfy high market demand and circumvent many ecological concerns. This review aims to present an overview of cellulose knowledge and technical biomedical applications such as antibacterial agents, antifouling, wound healing, drug delivery, tissue engineering, and bone regeneration. It includes an extensive bibliography of recent research findings from fundamental and applied investigations. Cellulose-based materials are tailorable to obtain suitable chemical, mechanical, and physical properties required for biomedical applications. The chemical structure of cellulose allows modifications and simple conjugation with several materials, including nanoparticles, without tedious efforts. They render the applications cheap, biocompatible, biodegradable, and easy to shape and process.
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17.
  • Abdelhamid, Hani Nasser, et al. (författare)
  • Cellulose-metal organic frameworks (CelloMOFs) hybrid materials and their multifaceted Applications : A review
  • 2022
  • Ingår i: Coordination chemistry reviews. - : Elsevier BV. - 0010-8545 .- 1873-3840. ; 451
  • Forskningsöversikt (refereegranskat)abstract
    • Cellulose-MOFs (CelloMOFs) are attractive hybrid materials that make available a range of hitherto unattainable properties by conjugating cellulosic materials with metal-organic frameworks (MOFs). CelloMOFs have demonstrated a great potential to be applied in several fields such as water remediation, air purification, gas storage, sensing/biosensing, and biomedicine. CelloMOFs can act as an efficient adsorbent to remove emerging contaminants such as metals, dyes, drugs, antibiotics, pesticides, and oils in water via adsorption. They can be also used as catalysts for catalytic degradation, reduction, and oxidation of organic pollutants. They have been applied as filters for air purification via removing greenhouse gases such as carbon dioxide (CO2), volatile organic compounds (VOCs), and particulate matter (PMs). Biomedical applications such as antibacterial, drug delivery, biosensing were also reported for CelloMOFs materials. This review summarized the synthesis, characterization, and applications of cellulose-MOFs materials. It covered a broad overview of the status of the combination of cellulose in micron to nanoscale with MOFs. At the end of the review, the challenges and outlook regarding CelloMOFs were discussed. Hopefully, this review will be a useful guide for researchers and scientists who are looking for quick access to relevant references about CelloMOFs hybrid materials and their applications.
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18.
  • Abdelhamid, Hani Nasser, et al. (författare)
  • Cellulose-zeolitic imidazolate frameworks (CelloZIFs) for multifunctional environmental remediation : Adsorption and catalytic degradation
  • 2021
  • Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 426
  • Tidskriftsartikel (refereegranskat)abstract
    • The crystal growth of zeolitic imidazolate frameworks (ZIFs) on biopolymers such as cellulose is a promising method for obtaining hybrid materials that combinenatural and synthetic materials. Cellulose derivative viz. 2,2,6,6-tetramethylpiperidine-1-oxylradical (TEMPO)-mediated oxidized nanocellulose (TOCNF) was used to modulate the crystal growth of ZIF-8 (denoted as CelloZIF-8) and ZIF-L (CelloZIF-L). The synthesis procedure occurred in water at room temperature with and without NaOH. The reaction parameters such as the sequence of the chemical's addition and reactant molar ratio were investigated. The phases formed during the crystal growth were monitored. The data analysis ensured the presence of zinc hydroxide nitrate nanosheets modified TOCNF during the crystallization of CelloZIFs. These phases were converted to pure phases ofCelloZIF-8 and CelloZIF-L. The resultant CelloZIFs materials were used for the adsorption ofcarbon dioxide (CO2), metal ions, and dyes. The materials exhibited high selectivity with reasonable efficiency (100%) toward the adsorption of anionic dyes such as methyl blue (MeB). They can also be used as a catalyst for dye degradation via hydrogenation with an efficiency of 100%. CelloZIF crystals can be loaded into a filter paper for simple, fast, and selective adsorption of MeB from a dye mixture. The materials are recyclable for five cycles without significant loss of their performance. The mechanisms of adsorption and catalysis were also investigated.
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19.
  • Abdelhamid, Hani Nasser, et al. (författare)
  • In-situ growth of zeolitic imidazolate frameworks into a cellulosic filter paper for the reduction of 4-nitrophenol
  • 2021
  • Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 274
  • Tidskriftsartikel (refereegranskat)abstract
    • Whatman (R) cellulosic filter paper was used as a substrate for the synthesis of two zeolitic imidazolate frameworks (ZIFs); ZIF-8 and ZIF-67 with and without 2,2,6,6-tetramethyl-1-piperidine oxoammonium salt (TEMPO) oxidized cellulose nanofibril (TOCNF). All synthesis procedures take place at room temperature via a one-pot procedure. The synthesis steps were followed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transforms infrared (FT-IR). Data indicated the formation of metal oxide that converted to a pure phase of ZIFs after the addition of the organic linker i.e. 2-methyl imidazole (Hmim). The materials were characterized using XRD, FT-IR, SEM, energy dispersive X-ray (EDX), nitrogen adsorption-desorption isotherms, and X-ray photoelectron microscope (XPS). Data analysis confirms the synthesis of ZIFs into Whatman (R) filter paper. The materials were used for the reduction of pollutants such as 4-nitrophenol (4-NP) compound to 4-aminophenol (4-AP). The materials exhibit high potential for water treatment and may open new exploration for hybrid materials consisting of cellulose and ZIFs.
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20.
  • Abdelhamid, Hani Nasser, 1986-, et al. (författare)
  • Three-Dimensional Printing of Cellulose/Covalent Organic Frameworks (CelloCOFs) for CO2 Adsorption and Water Treatment
  • 2023
  • Ingår i: ACS Applied Materials and Interfaces. - 1944-8244 .- 1944-8252. ; 15:51, s. 59795-59805
  • Tidskriftsartikel (refereegranskat)abstract
    • The development of porous organic polymers, specifically covalent organic frameworks (COFs), has facilitated the advancement of numerous applications. Nevertheless, the limited availability of COFs solely in powder form imposes constraints on their potential applications. Furthermore, it is worth noting that COFs tend to undergo aggregation, leading to a decrease in the number of active sites available within the material. This work presents a comprehensive methodology for the transformation of a COF into three-dimensional (3D) scaffolds using the technique of 3D printing. As part of the 3D printing process, a composite material called CelloCOF was created by combining cellulose nanofibrils (CNF), sodium alginate, and COF materials (i.e., COF-1 and COF-2). The intervention successfully mitigated the agglomeration of the COF nanoparticles, resulting in the creation of abundant active sites that can be effectively utilized for adsorption purposes. The method of 3D printing can be described as a simple and basic procedure that can be adapted to accommodate hierarchical porous materials with distinct micro- and macropore regimes. This technology demonstrates versatility in its use across a range of COF materials. The adsorption capacities of 3D CelloCOF materials were evaluated for three different adsorbates: carbon dioxide (CO2), heavy metal ions, and perfluorooctanesulfonic acid (PFOS). The results showed that the materials exhibited adsorption capabilities of 19.9, 7.4–34, and 118.5–410.8 mg/g for CO2, PFOS, and heavy metals, respectively. The adsorption properties of the material were found to be outstanding, exhibiting a high degree of recyclability and exceptional selectivity. Based on our research findings, it is conceivable that the utilization of custom-designed composites based on COFs could present new opportunities in the realm of water and air purification.
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21.
  • Adler, Anneli, et al. (författare)
  • Lignin-first biorefining of Nordic poplar to produce cellulose fibers could displace cotton production on agricultural lands
  • 2022
  • Ingår i: Joule. - : Elsevier BV. - 2542-4351. ; 6:8, s. 1845-1858
  • Tidskriftsartikel (refereegranskat)abstract
    • Here, we show that lignin-first biorefining of poplar can enable the production of dissolving cellulose pulp that can produce regenerated cellulose, which could substitute cotton. These results in turn indicate that agricultural land dedicated to cotton could be reclaimed for food production by extending poplar plantations to produce textile fibers. Based on climate-adapted poplar clones capable of growth on marginal lands in the Nordic region, we estimate an environmentally sustainable annual biomass production of ∼11 tonnes/ha. At scale, lignin-first biorefining of this poplar could annually generate 2.4 tonnes/ha of dissolving pulp for textiles and 1.1 m3 biofuels. Life cycle assessment indicates that, relative to cotton production, this approach could substantially reduce water consumption and identifies certain areas for further improvement. Overall, this work highlights a new value chain to reduce the environmental footprint of textiles, chemicals, and biofuels while enabling land reclamation and water savings from cotton back to food production.
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22.
  • Aguilar-Sanchez, Andrea, et al. (författare)
  • Charged ultrafiltration membranes based on TEMPO-oxidized cellulose nanofibrils/poly(vinyl alcohol) antifouling coating
  • 2021
  • Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 11:12, s. 6859-6868
  • Tidskriftsartikel (refereegranskat)abstract
    • This study reports the potential of TEMPO-oxidized cellulose nanofibrils (T-CNF)/poly(vinyl alcohol) (PVA) coatings to develop functionalized membranes in the ultrafiltration regime with outstanding antifouling performance and dimensional/pH stability. PVA acts as an anchoring phase interacting with the polyethersulfone (PES) substrate and stabilizing for the hygroscopic T-CNF via crosslinking. The T-CNF/PVA coated PES membranes showed a nano-textured surface, a change in the surface charge, and improved mechanical properties compared to the original PES substrate. A low reduction (4%) in permeance was observed for the coated membranes, attributable to the nanometric coating thickness, surface charge, and hydrophilic nature of the coated layer. The coated membranes exhibited charge specific adsorption driven by electrostatic interaction combined with rejection due to size exclusion (MWCO 530 kDa that correspond to a size of similar to 35-40 nm). Furthermore, a significant reduction in organic fouling and biofouling was found for T-CNF/PVA coated membranes when exposed to BSA and E. coli. The results demonstrate the potential of simple modifications using nanocellulose to manipulate the pore structure and surface chemistry of commercially available membranes without compromising on permeability and mechanical stability.
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23.
  • Aguilar-Sánchez, Andrea, 1987-, et al. (författare)
  • Nano-cellulose coatings for antifouling and mechanically enhanced polyethersulfone (PES) membranes
  • 2019
  • Ingår i: Nordic Polymer Days 2019. ; , s. 92-92
  • Konferensbidrag (refereegranskat)abstract
    • Membrane technology is commonly used for filtration processes of industrial wastewater. Using membranes for water filtration is a safe and energy efficient solution. One of the main problems that arises during the usage of membranes is the fouling effects. Fouling increases the membrane separation resistance, reduces productivity due to a flux decline and affect membrane selectivity. These effects can be avoid by modifying the surface of the membranes using bio-based materials such as nano-cellulose. Nano-cellulose is a great example of a material obtained from renewable resources, which provides high reinforcement and antifouling properties to membranes.The aim of this work was the development of coatings with cellulose nano-crystals (CNC) and Tempooxidized cellulose nano-fribrils (T-CNF) using polyvinyl-alcohol (PVOH), as binding phase to enhance mechanical and antifouling properties over pure commercial PES membranes. The coatings were chemically crosslinked to increase mechanical properties and to improve stability of the coating and avoid swelling. It is expected that by avoiding swelling, permeability remains stable through time. All coating formulations remained stable after 10 hours of crossflow filtration. Mechanical properties of the coated membranes were improved in both dry and wet conditions, showing higher values of tensile strenght and E modulus compared to the uncoated ones. In addition, coated membranes showed high hydrophilicity and low adherence of bovine serum albumin (BSA).The coatings developed showed stability over PES membranes and provide them with a nanostructured surface which showed an extended durability in use. The modified surface membranes presented good mechanical properties in dry and wet conditions, high flux, high hydrophilicity, resistance to BSA fouling and to different pH environments. Moreover, these modified membranes showed promising results for fast upscaling at industrial level due to the simplicity of the coating process and the availability of the materials in the market.
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24.
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25.
  • Aguilar Sánchez, Andrea, 1987- (författare)
  • Nanopolysaccharide coatings for functional surfaces in water-treatment materials : From mechanisms to process scalability
  • 2022
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • In this thesis, materials from renewable resources were used to develop functionalized surfaces for water treatment. The work is thus inspired by, and contributes to, the United Nations sustainable goals of: (i) clean water and sanitation, (ii) climate action, (iii) responsible consumption and production, (iv) life below water, and (v) partnerships for the goals.Nanopolysaccharides, most specifically nanocellulose and nanochitin, are great candidates for functional and renewable materials for multiple applications, including the treatment of water and wastewater. This thesis focused on the formulation of different types of nanopolysaccharide-based coatings to enhance the performance of commercially available membranes and cellulose fabrics. We developed a simple waterborne layer-by-layer cellulose nanocrystals (CNC) and TEMPO-oxidized cellulose nanofibrils (T-CNF) coating for commercially available membranes. By changing the surface and pore structure of the membrane, the coating tuned which substrates could pass through the membrane, improved antifouling performanced, and when derived from T-CNF, it was harmful to bacterial colonization. Considering the observed T-CNF’s effect on bacteria, we developed a chemically crosslinked T-CNF/Poly(vinyl) alcohol (PVA) coating with outstanding antibiofouling performance, ion adsorption/rejection combined with size exclusion, and with dimensional and pH stability. Furthermore, we used a surface-impregnation approach based on bio-based nanotechnology which resulted in highly efficient, with improved mechanical properties, and fully bio-based high-flux water filtration membranes using commercially available nonwoven fabrics. Membranes with coatings prepared from CNC, chitin nanocrystals (ChNC) and T-CNF separated particles in the size range of bacteria and viruses, and those prepared from also T-CNF showed high microplastic filtration efficiency. Moreover, membrane coating based on ChNC and T-CNF had outstanding antibacterial properties.Overall, we demonstrated that nanopolysaccharide coatings on membranes could provide a significant reduction in organic fouling and biofilm formation while enabling the adsorption of ions and separation of microplastics. In the case of biofilm formation, the functional group and surface charge of the different nanopolysaccharides determined the effect over bacteria, indicating that surfaces could be tailored against microbes. In addition, we directly compared the effect of the different nanopolysaccharides of interest (CNC, T-CNF, ligno-celullose nanocrystals (L-CNC), and ChNC) on bacterial viability and biofilm formation, and found a great difference between the different types of nanocellulose and a different mechanism for nanochitin. Thorough, none of the nanopolysaccharides displayed cytotoxic effects while in indirect contact with the bacterial cells. Nevertheless, T-CNF, ChNC and L-CNC showed a cytostatic effect on bacterial proliferation. Furthermore, the nanomechanical properties of the bacterial cells and interacting forces between the nanopolysaccharides and Escherichia coli (E. coli) were affected when in direct contact with the nanopolysaccharide surfaces.Lastly, we upscaled one of our coating processes, demonstrating that the method could be easily implemented at an industrial level. The impact of this thesis relies on the effectiveness of the coatings, the different types of functionalities observed, the demonstrated fast implementation at an industrial scale, and the potential to extrapolate this technology to other applications.
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26.
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27.
  • Aguilar-Sanchez, Andrea, et al. (författare)
  • Waterborne nanocellulose coatings for improving the antifouling and antibacterial properties of polyethersulfone membranes
  • 2021
  • Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 620
  • Tidskriftsartikel (refereegranskat)abstract
    • This article presents a waterborne nanocellulose coating process to change the surface characteristics and mitigate fouling of commercially available polyethersulfone (PES) microfiltration membranes. An extensive comparative study between nanoporous and nano-textured layers composed of cellulose nanocrystals (CNC) or TEMPO-oxidized cellulose nanofibrils (T-CNF), which were coated on the PES membrane by taking advantage of the electrostatic interactions between the PES substrate, a polyallylamine hydrochloride (PAHC1) anchoring layer, and the nanocellulose functional layer. Coated PES membranes exhibited decreased surface roughness and pore sizes as well as rejection of compounds with a M-w above 150 kDa, while the water permeability and mechanical properties of remained largely unaffected. The coatings improved the wettability as confirmed by a reduction of the contact angle by up to 52% and exhibited a higher negative surface charge compared to the uncoated membranes over a pH range of 4-8. A significant reduction in organic fouling was observed for the coated membranes demonstrated by bovine serum albumin (BSA) adsorption studies on T-CNF and CNC surfaces using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), UV-vis spectroscopy and FTIR mapping after exposing the membranes to dynamic adsorption of BSA. The T-CNF coating exhibited effective antibacterial action against Escherichia coli (E. coli) attributed to the pH reduction effect induced by the carboxyl groups; while CNC coatings did not show this property. This work demonstrates a simple, green, and easy-to-scale layer-by-layer coating process to tune the membrane rejection and to improve antifouling and antibacterial properties of commercially available membranes.
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28.
  • Aitomäki, Yvonne, et al. (författare)
  • Impregnation of cellulose nanofibre networks with a thermoplastic polymer
  • 2013
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • The emphasis of this study have been to study if impregnation of cellulose nanofibre networks can be made using a thermoplastic polymer as a matrix and to estimate the reinforcing efficiency of the cellulose nanofibres in this composite. A nanofibre network with higher porosity that water-dried nanofibre network was prepared from a cellulose waste byproduct (sludge). This was impregnated using a diluted solution of cellulose acetate butyrate polymer to produce a 60 wt. % CNF/CAB composite. This composite was characterized using microscopy and mechanical testing. High porosity is seen in the SEM images of the acetone-dried fibre network and SEM and film transparency was used to qualitatively assess the impregnation of the network. A significant improvement in the visible light transmittance was observed for the nanocomposite film compared to the nanofibre network as a result of the impregnation. The reinforcing efficiency was calculated based on a model of the nanocomposite and compared to other nanocomposites in the literature. The efficiency factor takes into account the volume fraction and the stiffness of the matrix. This showed that this CNF/CAB combination is similar in efficiency to CNF/PLA nanocomposites and more efficient that nanocomposites using when using stiffer matrices. It was also more efficient CNF nanocomposites based on Chitosan, which has the same stiffness. It is still however not as efficient as traditional glass polymer composites due to the random orientation of the fibres nor nanocomposites with very soft matrices due to the dominating network effect of the CNF in such composites. In conclusion, CAB impregnated cellulose nanofibre networks are promising biocomposite materials that could be used in applications where transparency and good mechanical properties are of interest. The key elements in the impregnation process of the nanocomposites were the use of a porous networks and a low viscosity thermoplastic resin solution.
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29.
  • Alanis, Andrés, et al. (författare)
  • Plasma surface-modification of cellulose nanocrystals : a green alternative towards mechanical reinforcement of ABS
  • 2019
  • Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 9:30, s. 17417-17424
  • Tidskriftsartikel (refereegranskat)abstract
    • This article proposes a strategy to functionalize cellulose nanocrystals by means of plasma-surface modification utilizing monomers of different nature: caprolactone, styrene and farnesene. The surface characteristics of the nanocrystals were studied by different techniques including XPS, FTIR and STEM, demonstrating that this technique allows a successful functionalization, yielding homogenous functionalization which does not alter the rod-like shape of the nanocrystals, and therefore their anisotropic behavior. We have furthermore studied the employment of the modified nanocrystals as reinforcement additive of ABS, which significantly enhanced the impact resistance of the thermoplastic, which could have great implications for industrial applications.
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30.
  • Apostolopoulou Kalkavoura, Varvara, 1988-, et al. (författare)
  • In Situ Functionalisation and Upcycling of Post-Consumer Textile Blends into 3D Printable Nanocomposite Filaments
  • 2024
  • Ingår i: Advanced Sustainable Systems. - 2366-7486 .- 2366-7486.
  • Tidskriftsartikel (refereegranskat)abstract
    • The linear lifecycle of the textile industry contributes to the enormous waste generation of post-consumer garments. Recycling or repurposing of post-consumer garments typically requires separation of the individual components. This study describes a novel and facile chemo-thermo-mechanical method for producing extrudable pellets, involving one-pot, 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation of post-consumer polycotton textiles, followed by mild mechanical treatment, all without isolating the constituents of the polycotton blend. The oxidized blend with high cellulose and carboxylate content of 1221 ± 82 mmol COO− per kg of cotton, is pelletised into a masterbatch and further in situ extruded into nanocomposite filaments for 3D printing. The carboxyl groups introduced on the polycotton-based filters enable cotton fibrillation into nanoscaled fibers during mechanical treatment and extrusion resulting to a variety of functional and high surface-finish quality models, including filters and fashion accessories. The electrostatic interactions with positively charged species, such as methylene blue (MB), facilitate their adsorption from water while exhibiting promising adsorption capacities. The adsorption of MB follows the Freundlich model and depends on the printed porosity of the filter. A “trash to treasure” concept for textile waste is further corroborated through the use of the developed 3D printing filament into commodity products.
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31.
  • Apostolopoulou Kalkavoura, Varvara, 1988-, et al. (författare)
  • Trash to treasure: 3D printing of waste-based polycotton composite for the production of water filters and commodity products
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • The recycling of polycotton without separating its constituents for high-performance applications has not yet been fully investigated. In this study, we propose a simple and efficient method involving one-pot, 2, 2, 6, 6 – tetramethylpiperdine-1-oxyl (TEMPO) - oxidation of post-consumer polycotton textile waste followed by lenient mechanical fibrillation. Successful chemical modification of the polycotton waste was confirmed by the Fourier-transform infrared (FT-IR) spectroscopy measurements, in which the presence of carboxyl groups introduced during the TEMPO-oxidation was observed. Moreover, the waste-based pellets were single-screw extruded into 3D printing filaments, which were further processed via desktop Fused Deposition Modelling (FDM) 3D printer.FDM processing was carried out without hindrance. The textile-based filament was used for the fabrication of a variety of high surface-finish quality models, which presented diverse geometries and porosity architectures. The versatility of the developed 3D printed models was demonstrated through both, their potential to be utilized as fashion accessories, and by evaluating their performance in water treatment applications. Taking advantage of the introduction of negatively charged carboxylic groups onto the polycotton-based materials, which was expected to facilitate the electrostatic interactions with positively charged species, the 3D printed filters were tested for removal of cationic dye methylene blue (MB) from water in a batch adsorption study. The adsorption followed Langmuir model, with a maximim adsorption capacity of 3 µmol/g. Overall, this work presents a novel approach for the upcycling of polycotton waste into functional filament suitable for a variety of 3D printing, and further, engineering applications. The development of composite filaments and their mechanical and adsorption properties pave the way for future research within valorisation of textile-based waste.
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32.
  • Bondeson, Daniel, et al. (författare)
  • Optimization of the Isolation of Nanocrystals from Microcrystalline Cellulose by Acid Hydrolysis
  • 2006
  • Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 13:2, s. 171-180
  • Tidskriftsartikel (refereegranskat)abstract
    • The objective of this work was to find a rapid, high-yield process to obtain an aqueous stable colloid suspension of cellulose nanocrystals/whiskers. Large quantities are required since these whiskers are designed to be extruded into polymers in the production of nano-biocomposites. Microcrystalline cellulose (MCC), derived from Norway spruce (Picea abies), was used as the starting material. The processing parameters have been optimized by using response surface methodology. The factors that varied during the process were the concentration of MCC and sulfuric acid, the hydrolysis time and temperature, and the ultrasonic treatment time. Responses measured were the median size of the cellulose particles/whiskers and yield. The surface charge as calculated from conductometric titration, microscopic examinations (optical and transmission electron microscopy), and observation of birefringence were also investigated in order to determine the outcome (efficiency) of the process. With a sulfuric acid concentration of 63.5% (w/w), it was possible to obtain cellulose nanocrystals/whiskers with a length between 200 and 400 nm and a width less than 10 nm in approximately 2 h with a yield of 30% (of initial weight).
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33.
  • Bozic, Mojca, et al. (författare)
  • Enzymatic phosphorylation of cellulose nanofibers to new highly-ions adsorbing, flame-retardant and hydroxyapatite-growth induced natural nanoparticles
  • 2014
  • Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 21:4, s. 2713-2726
  • Tidskriftsartikel (refereegranskat)abstract
    • This study confirms the enzyme-mediated phosphorylation of cellulose nanofibers (CNF) by using hexokinase and adenosine-5’-triphosphate (ATP) in the presence of Mg-ions, resulting in a phosphate group’s creation predominantly at C-6-O positioned hydroxyl groups of cellulose monomer rings. A proof-of-concept is provided using 12C CPMAS, 31P MAS NMR, ATR-FTIR and XPS analyzing methods. The degree of substitution is determined for the first time by ATR-FTIR spectroscopy being in a correlation with XPS and potentiometric titration results. From the thermal degradation measurements using TGA, the C-6-O phosphorylation was found to noticeably prevent the CNF derivatives from weight loss in the pyrolysis process, thus, providing them flame-resistance functionality. Furthermore, phosphorylation significantly enhanced adsorption capacity of Fe3+ ions making them interesting for fabrication of biobased filters and membranes. Finally, the biomimetic growth of Ca-P crystals (hydroxyapatite) in simulated body fluid was characterized by SEM and showing further practicability for biomedical materials.
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34.
  • Cárdenas Bates, Ilse Ileana, et al. (författare)
  • Cellulose reinforced electrospun chitosan nanofibers bio-based composite sorbent for water treatment applications
  • 2021
  • Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; :28, s. 4865-4885
  • Tidskriftsartikel (refereegranskat)abstract
    • Electrospun chitosan-polyethylene oxide/TEMPO-oxidized cellulose (CS-PEO/TOC) bio-based composite was fabricated for the first time for water treatment applications. This new concept allows cellulose and chitosan to be combined in a simpler and efficient way, avoiding the use of harmful solvents, compared to previously published related work. The Sandwich-like material is composed of a porous oxidized cellulosic fibers central core (TOC handsheet) and a thin layer of electrospun CS-PEO nanofibers on both sides of the core. Average diameters for CS-PEO and TOC were 159.3 +/- 33.7 nm and 21.7 +/- 5.1 mu m, respectively. Fourier Transform Infrared Spectroscopy (FTIR) was carried out on the bio-based composite. Results suggest that no covalent bonds are involved but rather electrostatic interactions occur which allows bonding of the electrospun nanofiber layers on TOC core and no delamination. CS-PEO electrospinning time was varied to study the effect of nanofiber's coating weight on strength, permeability and adsorption capacity of the bio-based material. Mechanical properties of the composite were improved over the electrospun nanofiber mat. The CS-PEO provides greater elasticity (strain%) and the TOC provides a higher tensile strength to the material. However, tensile index was reduced by 48% with electrospinning time, while burst index was almost constant. The best conditions were achieved for 2 h electrospinning time. Under these conditions, a high permeable material (290.13 L/m(2) hbar) was developed. The adsorption capacity for Cu (II) ions reached up to 27% with only 12 mg of chitosan onto the CS-PEO/TOC (12.42 mg/g). The data fit better to the pseudo-second order model, suggesting chemisorption as the main mechanism involved for copper adsorption. This study opens-up potential opportunities for the development of a robust material for wastewater applications at an industrial scale.
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35.
  • Colic, Miodrag, et al. (författare)
  • Cytocompatibility and immunomodulatory properties of wood based nanofibrillated cellulose
  • 2015
  • Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 22:1, s. 763-778
  • Tidskriftsartikel (refereegranskat)abstract
    • Cellulose nanofibrils (CNFs), unique and promising natural materials have gained significant attention recently for biomedical applications, due to their special biomechanical characteristics, surface chemistry, good biocompatibility and low toxicity. However, their long bio-persistence within organisms may provoke chronic immune reactions and this aspect of CNFs has not been studied to date. Therefore, the aim of this work was to examine and compare the biocompatibility and immunomodulatory properties of CNFs in vitro. CNFs (diameters of 10-70nm; lengths of a few microns) were prepared from Norway spruce (Picea abies) by mechanical fibrillation and high pressure homogenisation. L929 cells, rat thymocytes or human peripheral blood mononuclear cells (PBMNCs) were cultivated with CNFs. None of the six concentrations of CNFs (31.25µg/ml – 1mg/ml) induced cytotoxicity and oxidative stress in the L929 cells, nor induced necrosis and apoptosis of the thymocytes and PBMNCs. Higher concentrations (250µg/ml – 1mg/ml) slightly inhibited the metabolic activities of the L929 cells as a consequence of inhibited proliferation. The same concentrations of CNFs suppressed the proliferation of PBMNCs to phytohemaglutinine, a T-cell mitogen, and the process was followed by down-regulation of interleukin-2 (IL-2) and interferon-γ (IFN-γ) production. The highest concentration of CNFs inhibited IL-17A but increased IL-10 and IL-6 production. The secretions of the inflammatory cytokines, IL-1β and the tumor necrosis factor-α (TNF-α) as well as Th2 cytokine (IL-4), remained unaltered. In conclusion, the results suggest that these CNFs are biocompatible, non-inflammatory and non-immunogenic nanomaterial. Higher concentrations seem to be tollerogenic to the immune system, a characteristic very desirable for implantable biomaterials.
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36.
  • Deepa, B., et al. (författare)
  • Utilization of various lignocellulosic biomass for the production of nanocellulose : a comparative study
  • 2015
  • Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 22:2, s. 1075-1090
  • Tidskriftsartikel (refereegranskat)abstract
    • Nanocellulose was successfully extracted from five different lignocellulosic biomass sources viz. banana rachis, sisal, kapok, pineapple leaf and coir using a combination of chemical treatments such as alkaline treatment, bleaching and acid hydrolysis. The shape, size and surface properties of the nanocellulose generally depend on the source and hydrolysis conditions. A comparative study of the fundamental properties of raw material, bleached and nanocellulose was carried out by means of Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, transmission electron microscopy, birefringence, X-ray diffraction, inverse gas chromatography and thermogravimetric analysis. Through the characterization of the nanocellulose obtained from different sources, the isolated nanocellulose showed an average diameter in the range of 10–25 nm, high crystallinity, high thermal stability and a great potential to be used with acid coupling agents due to a predominantly basic surface. This work provides an insight into the effective utilization of a variety of plant biomass as a potential source for nanocellulose extraction.
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37.
  • Di Francesco, Davide, 1989-, et al. (författare)
  • A New Family of Renewable Thermosets : Kraft Lignin Poly-adipates
  • 2022
  • Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 15:11
  • Tidskriftsartikel (refereegranskat)abstract
    • Thermosetting polymeric materials have advantageous properties and are therefore used in numerous applications. In this study, it was hypothesized and ultimately shown that thermosets could be derived from comparably sustainable sub-components. A two-step procedure to produce a thermoset comprising of Kraft lignin (KL) and the cross-linker adipic acid (AdA) was developed. The cross-linking was activated by means of an acetylating agent comprising isopropenyl acetate (IPA) to form a cross-linking mixture (CLM). The cross-linking was confirmed by FTIR and solid-state NMR spectroscopy, and the esterification reactions were further studied using model compounds. When the KL lignin was mixed with the CLM, partial esterification occurred to yield a homogeneous viscous liquid that could easily be poured into a mold, as the first step in the procedure. Without any additions, the mold was heated and the material transformed into a thermoset by reaction of the two carboxylic acid-derivatives of AdA and KL in the second step.
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38.
  • Dobryden, Illia (författare)
  • Surface characterization and force measurements applied to industrial materials with atomic force microscopy
  • 2012
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The thesis focuses on the application of force measurements with atomic force microscopy (AFM) on materials with a few surface contacts/asperities and chemically modified surfaces. The technique allows measurements of ultra-small intermolecular and surface forces, down to the piconewton level. The force measurements between surfaces of well-defined geometry are often used to measure and model the interaction between different systems of charged and neutral surfaces in various environments. However, detailed knowledge of the contacting surface profile geometry and surface properties is required to model the fundamental forces involved in the interaction. The preparation of such well-defined and idealized surfaces is often time consuming and the surfaces may not possess the behavior and properties of a source material in real processes, such as in industry. Moreover, external factors such as magnetic fields, ionic strengths and pH-values in a solution, may further complicate the evaluation. Hence, it is desirable to explore and develop techniques for trustable measurements of forces between “real” surfaces. These are often a complex composition of various force interactions and multiple surface contacts.The AFM probe technique was explored to measure force interactions between “real” particle surfaces. The work shows the applicability of the AFM technique to study the interaction forces despite the forecasted difficulties with the roughness of the particles.A technique to measure the adhesion and work of adhesion from AFM force curves was implemented and used. The thermal tune method was implemented in our commercial NT-MDT microscope to determine cantilever spring constants. The force interactions between natural microsize (m-s) magnetite particles and synthetic nanosize (n-s) magnetite particles were studied in calcium solution with concentrations of 1, 10, 100 mM and at pH values 4, 6 and 10. The changes in force interactions, due to variations in calcium concentration and pH were investigated. The adhesion force change with the concentration and pH was similar for m-s/m-s and m-s/n-s systems, and the adhesion force increased with the concentration at pH 6, except for the highest calcium concentration of 100 mM at pH 10. It was found that the magnetite surface modification could appear at the highest calcium concentration at pH 10. Moreover, the thesis contains preliminary results of the force interaction study between natural and synthetic bentonite-magnetite particles in calcium solution with concentrations of 1, 10 and 100 mM at pH 6.The influence of roughness on the calculation of contact mechanics parameters were studied with AFM and Vertical Scanning Interferometry (VSI). This is important for future development of a model to describe and characterize the force interaction between samples with multiple surface contacts. It was found that the optical artifacts, induced by VSI, have a large influence on all the roughness parameters calculated on the calibration grids, which represent extreme surface topographies.
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39.
  • Duchemin, Benoit, et al. (författare)
  • All-cellulose composites by partial dissolution in the ionic liquid 1-butyl-3-methylimidazolium chloride
  • 2009
  • Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier BV. - 1359-835X .- 1878-5840. ; 40:12, s. 2031-2037
  • Tidskriftsartikel (refereegranskat)abstract
    • Fully bio-based and biodegradable all-cellulose composites were prepared in the form of films by partial dissolution of two cellulose sources: a commercially available microfibrillated cellulose (MFC) and filter paper (FP). The solvent selected for this work was the ionic liquid 1-butyl-3-methylimidazolium chloride ([C4mim]Cl). Both cellulose sources were partially dissolved at 80 °C and consolidated by partial dissolution, resulting in excellent mechanical properties. X-ray diffraction and electron microscopy demonstrated that partial dissolution was a viable path to transform FP into a continuous paracrystalline matrix reinforced with cellulose I crystallites. In contrast, partially dissolved MFC was not as thoroughly dissolved and large amounts of undissolved material were still visible along the center line of the films after the longest dissolution times. Consequently, partially dissolved MFC retained its initially high crystallinity. The degree of polymerization of the materials after dissolution was significantly reduced.
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40.
  •  
41.
  • Esmaeili, Chakavak, et al. (författare)
  • Synergy Effect of Nanocrystalline Cellulose for the Biosensing Detection of Glucose
  • 2015
  • Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 15:10, s. 24681-24697
  • Tidskriftsartikel (refereegranskat)abstract
    • Integrating polypyrrole-cellulose nanocrystal-based composites with glucose oxidase (GOx) as a new sensing regime was investigated. Polypyrrole-cellulose nanocrystal (PPy-CNC)-based composite as a novel immobilization membrane with unique physicochemical properties was found to enhance biosensor performance. Field emission scanning electron microscopy (FESEM) images showed that fibers were nanosized and porous, which is appropriate for accommodating enzymes and increasing electron transfer kinetics. The voltammetric results showed that the native structure and biocatalytic activity of GOx immobilized on the PPy-CNC nanocomposite remained and exhibited a high sensitivity (ca. 0.73 μA·mM(-1)), with a high dynamic response ranging from 1.0 to 20 mM glucose. The modified glucose biosensor exhibits a limit of detection (LOD) of (50 ± 10) µM and also excludes interfering species, such as ascorbic acid, uric acid, and cholesterol, which makes this sensor suitable for glucose determination in real samples. This sensor displays an acceptable reproducibility and stability over time. The current response was maintained over 95% of the initial value after 17 days, and the current difference measurement obtained using different electrodes provided a relative standard deviation (RSD) of 4.47%.
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42.
  •  
43.
  • Fatima, Nowshir, et al. (författare)
  • Wet Clutch Friction Interfaces under Water Contaminated Lubricant Conditions
  • 2016
  • Ingår i: Tribology Transactions. - : Informa UK Limited. - 1040-2004 .- 1547-397X. ; 59:3, s. 441-450
  • Tidskriftsartikel (refereegranskat)abstract
    • The performance of wet clutches used for automatic transmissions or other applications usually includes the desired positive friction characteristics and a shudder-free torque generation. Changes in the operating variables such as the lubricant conditions influence the formation of tribofilm, friction characteristics and can alter the degradation of the friction interfaces. In this work, the friction characteristics and degradation of the paper-steel friction interfaces were monitored when a commercial fully-formulated automatic transmission fluid (ATF) was contaminated with water. It was found that water in ATF influenced the clutch stability by increasing the mean coefficient of friction (µ) and the negative friction-velocity slope. Surface studies of the post-test friction interfaces clearly indicated reduced surface porosity and permeability, increased wettability and changed elemental composition on the contacting surfaces after tested with water- contaminated ATF. Moreover, water-contaminated paper-liners’ thermal decomposition shifted to a lower temperature compared to an uncontaminated liner during thermal analyses. These results displayed faster degradation and reduced service life of the clutch friction interfaces for water contamination. The resultant surface condition can be associated with the observed unstable friction and negative friction-velocity slopes.
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44.
  • Fijoł, Natalia, et al. (författare)
  • 3D-printable biopolymer-based materials for water treatment : A review
  • 2022
  • Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 430
  • Forskningsöversikt (refereegranskat)abstract
    • The global environmental concerns drive scientists all over the world to develop eco-friendly and sustainable alternatives to techniques and materials commonly used until now for water treatment applications. The relatively novel Additive manufacturing (AM) technology allows to process materials in a custom optimized, cost and time effective manner, while use of biobased materials minimizes the secondary pollution issue. Combining three-dimensional (3D) printing technology and biopolymer-based materials refines the water treatment industry, as it provides tailored water filtration systems easily available in the disadvantaged areas at low environmental impact and cost due to the raw materials' bio-origin and abundance. This review highlights the combination of various 3D printing techniques such as Fused deposition modelling (FDM), Direct ink wetting (DIW) and Stereolitography (SLA) with nature-derived biopolymers and biopolymerbased materials including chitosan, Polylactic acid (PLA), alginate and Cellulose acetate (CA) for their potential application within the water treatment industry with emphasis on oil separation and metal removal. Moreover, the environmental impact of the revised biopolymers is briefly discussed.
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45.
  • Fijoł, Natalia, et al. (författare)
  • 3D-printed monolithic biofilters based on a polylactic acid (PLA) - hydroxyapatite (HAp) composite for heavy metal removal from an aqueous medium
  • 2021
  • Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 11:51, s. 32408-32418
  • Tidskriftsartikel (refereegranskat)abstract
    • High flux, monolithic water purification filters based on polylactic acid (PLA) functionalised with fish scale extracted hydroxyapatite (HAp) were prepared by solvent-assisted blending and thermally induced phase separation (TIPS), followed by twin-screw extrusion into filaments and processed via three-dimensional (3D) printing. The printed filters with consistent pore geometry and channel interconnectivity as well as homogenous distribution of HAp in the PLA matrix showed adsorption capabilities towards heavy metals i.e. cadmium (Cd) and lead (Pb) with maximum adsorption capacity of 112.1 mg gHAp−1 and 360.5 mg gHAp−1 for the metal salt of Pb and Cd, respectively. The adsorption was found to be driven by a combination of ion exchange, dissolution and precipitation on HAp and surface complexation.
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46.
  • Fijoł, Natalia, 1994-, et al. (författare)
  • 3D printed polylactic acid (PLA) filters reinforced with polysaccharide nanofibers for metal ions capture and microplastics separation from water
  • 2023
  • Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 457
  • Tidskriftsartikel (refereegranskat)abstract
    • The need for multifunctional, robust, reusable, and high-flux filters is a constant challenge for sustainable water treatment. In this work, fully biobased and biodegradable water purification filters were developed and processed by the means of three-dimensional (3D) printing, more specifically by fused deposition modelling (FDM).The polylactic acid (PLA) – based composites reinforced with homogenously dispersed TEMPO-oxidized cellulose nanofibers (TCNF) or chitin nanofibers (ChNF) were prepared within a four-step process; i. melt blending, ii. thermally induced phase separation (TIPS) pelletization method, iii. freeze drying and iv. single-screw extrusion to 3D printing filaments. The monolithic, biocomposite filters were 3D printed in cylindrical as well as hourglass geometries with varying, multiscale pore architectures. The filters were designed to control the contact time between filter’s active surfaces and contaminants, tailoring their permeance.All printed filters exhibited high print quality and high water throughput as well as enhanced mechanical properties, compared to pristine PLA filters. The improved toughness values of the biocomposite filters clearly indicate the reinforcing effect of the homogenously dispersed nanofibers (NFs). The homogenous dispersion is attributed to the TIPS method. The NFs effect is also reflected in the adsorption capacity of the filters towards copper ions, which was shown to be as high as 234 and 208 mg/gNF for TCNF and ChNF reinforced filters, respectively, compared to just 4 mg/g for the pure PLA filters. Moreover, the biocomposite-based filters showed higher potential for removal of microplastics from laundry effluent water when compared to pure PLA filters with maximum separation efficiency of 54 % and 35 % for TCNF/PLA and ChNF/PLA filters, respectively compared to 26 % for pure PLA filters, all that while maintaining their high permeance.The combination of environmentally friendly materials with a cost and time-effective technology such as FDM allows the development of customized water filtration systems, which can be easily adapted in the areas most affected by the inaccessibility of clean water.
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47.
  • Fijoł, Natalia, 1994- (författare)
  • 3D printing of Green Water Purification Filters : Design towards Sustainable and Scalable Biocomposite Materials
  • 2023
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The globally escalating water pollution and water scarcity necessitates the development of efficient and sustainable water treatment technologies. This thesis investigates the feasibility of utilizing renewable and waste materials in the form of green composites for the fabrication of water purification filters via Fused Deposition Modelling (FDM).The first system studied within this thesis is based on the biobased thermoplastic polymer - polylactic acid (PLA), which serves as a composite matrix that is reinforced and functionalized with an array of green materials including fish-scale extracted hydroxyapatite (HAp), 2,2,6,6 – tetramethylpiperdine-1-oxyl (TEMPO) - oxidized cellulose nanofibers (TCNF), chitin nanofibers (ChNF), and bioinspired metal-organic framework – SU-101. All the developed PLA-based biocomposites exhibited great design flexibility and excellent printability, leading to the development of high surface-finish quality water purification filters of various geometries and porosity architectures. The developed filters successfully removed various contaminants from water. High capability for removal of metal ions from both, model solutions (reaching removal capacity towards Cu2+ ions of 208 mg/gNF and 234 mg/gNF for ChNF/PLA and TCNF/PLA filters, respectively, compared to only 4 mg/g for PLA filters), as well as from an actual mine effluent, reaching removal efficiency towards i.a. Mn2+ ions of over 50 % was demonstrated. Moreover, the developed TCNF/PLA and ChNF/PLA filters successfully removed microplastics from laundry effluent with over 70 % separation efficiency. The PLA-based biocomposite filters surface-functionalized with SU-101 were also suitable for the removal of cationic dye, methylene blue (MB), from water with removal efficiencies of over 40 %.The second composite system explored the possibility of using post-consumer polycotton textile waste as a functional entity for the polyethylene terephthalate glycol (PETG) matrix, for the fabrication of 3D printing filaments, which can be further processed into highly functional water purification filters by the FDM. The conducted TEMPO-mediated oxidation of the polycotton garments introduced negatively charged carboxylic groups onto the 3D printing filament’s surface and consequently, onto the 3D printed structures, yielding filters suitable for removal of cationic dyes, such as MB, from water.Apart from being evaluated for their ability to remove various contaminants from water, the filters have been subjected to a series of tests to assess the homogeneity of the filler dispersion in the polymer matrix as well as the filters’ permeability and mechanical stability. The high throughput character of the filters was demonstrated, as e.g., for the HAp/PLA filters the calculated flux reached 2x106 Lm-2h-1bar-1. The reinforcing impact of the nanospecies on the polymer matrix in the gradient porosity filters was investigated and so, it was shown that the addition of ChNF and TCNF fibers into PLA increases their Young’s modulus value from 550.7 ± 2.8 MPa, to 622.7 ± 1.6 MPa and 702.9 ± 5.4 MPa, respectively. Moreover, the lifespan of the filters was assessed by subjecting them to an accelerated ageing procedure in water, which have shown that the TCNF/PLA and ChNF/PLA filters could serve up to eight and five months, respectively, while maintaining their functionality and good mechanical performance. Furthermore, the study revealed that the filters are indeed biodegradable, as after prolonged exposure to water at elevated temperatures, they have fully disintegrated.Overall, the obtained results demonstrate the feasibility of combining renewable and recycled materials with 3D printing technology to create water purification filters suitable for the removal of a wide variety of contaminants from water.
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48.
  • Fijoł, Natalia, et al. (författare)
  • Accelerated ageing of 3D printed water purification filters based on PLA reinforced with green nanofibers
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • This study investigates the ageing behavior of polylactic acid (PLA) and PLA-based biocomposites reinforced with either 2,2,6,6-tetramethylpiperidine 1-oxyl radical (TEMPO) - oxidized cellulose nanofibers (TCNF) or chitin nanofibers (ChNF) in water. Cuboid water filters, which were processed by the means of fused deposition modelling (FMD), were subjected to ageing tests in water at varying temperatures for 19 weeks. Thermomechanical results show that while the addition of TCNF and ChNF improves the mechanical performance of PLA-based filters in dry conditions, it has the opposite effect after exposure to water. Impact of the prolonged exposure to water on the Young’s modulus (YM) and toughness values on the aged biocomposite specimens was more significant than that on the unmodified PLA filters. Moreover, a significant drop in the glass transition temperature (Tg) of approximately 10 ℃ was observed for both, TCNF/PLA and ChNF filters, after just 3 weeks of ageing. In comparison, the Tg of the pure PLA remains unaffected for up to 7 weeks. The mechanical tests allowed to estimate the service life of the 3D printed filters using the Arrhenius model. It was shown that the TCNF/PLA and ChNF/PLA filters can be utilized at room temperature water for up to 8 and 5 months, respectively, until they lose 50 % of their initial ability to resist deformation. In the same conditions, PLA filters can serve for up to 3.5 years. In conclusion, this study highlights the importance of considering the degradation behaviour of biocomposites when developing sustainable materials for water treatment applications.
  •  
49.
  • Fijoł, Natalia, 1994-, et al. (författare)
  • Accelerated ageing of 3D printed water purification filters based on PLA reinforced with green nanofibers
  • 2023
  • Ingår i: Polymer testing. - 0142-9418 .- 1873-2348. ; 129
  • Tidskriftsartikel (refereegranskat)abstract
    • This study investigates the ageing behavior of polylactic acid (PLA) and PLA-based biocomposites reinforced with either 2,2,6,6-tetramethylpiperidine 1-oxyl radical (TEMPO) - oxidized cellulose nanofibers (TCNF) or chitin nanofibers (ChNF) in water. Fused deposition modeling (FDM) was used to create water filters, which underwent aging tests at various temperatures over 19 weeks. Thermomechanical results show that while the addition of TCNF and ChNF improves the mechanical performance of PLA-based filters in dry conditions, it has the opposite effect after exposure to water. The impact of prolonged water exposure on Young's modulus and toughness was more significant in biocomposites than in unmodified PLA filters. The TCNF/PLA and ChNF/PLA filters saw a substantial ∼10 °C drop in glass transition temperature (Tg) after 3 weeks, while pure PLA remained nearly unaffected for up to 7 weeks. The mechanical tests allowed to estimate the service life of the 3D printed filters using the Arrhenius model. It was shown that the TCNF/PLA and ChNF/PLA filters can be utilized at room temperature water for up to 8 and 5 months, respectively, until they lose 50 % of their initial ability to resist deformation. In the same conditions, PLA filters can serve for up to 3.5 years. In conclusion, this study highlights the importance of considering the degradation behaviour of biocomposites when developing sustainable materials for water treatment applications.
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50.
  • Fijoł, Natalia, 1994-, et al. (författare)
  • MOF@Cell : 3D printed biobased filters anchored with a green metal–organic framework for effluent treatment
  • 2023
  • Ingår i: Journal of Materials Chemistry A. - 2050-7488 .- 2050-7496. ; 11:23, s. 12384-12394
  • Tidskriftsartikel (refereegranskat)abstract
    • Multifunctional, biobased materials processed by means of additive manufacturing technology can behighly applicable within the water treatment industry. This work summarizes a scalable and sustainablemethod of anchoring a green metal–organic framework (MOF) SU-101 onto the surface of 3D printed,biobased matrices built of polylactic acid (PLA)-based composites reinforced with TEMPO-oxidizedcellulose nanofibers (TCNFs). The two tested anchoring methods were hydrolysis via either concentratedhydrochloric acid treatment or via a photooxidation reaction using UV–ozone treatment. Stabledeposition of SU-101 distributed homogenously over the filter surface was achieved and confirmed byFT-IR, XPS and SEM measurements. The obtained 3D printed and functionalized MOF@PLA andMOF@TCNF/PLA (aka MOF@Cell) filters exhibit high efficiency in removing heavy metal ions from mineeffluent and methylene blue from contaminated water, as demonstrated through batch adsorptionexperiments. In addition to their potential for removal of contaminants from water, the MOF@Cell filtersalso exhibit excellent mechanical properties with a Young's modulus value of about 1200 MPa,demonstrating their potential for use in practical water treatment applications. The MOF@Cell filterswere able to maintain their structural integrity and filtration performance even after multiple cycles ofuse and regeneration. This study highlights the potential of multifunctional, biobased materials processedby additive manufacturing technology as a cost-effective alternative to traditional water treatmentmethods. The MOF@Cell filters presented in this study demonstrate high efficiency, durability, andreusability, making them promising candidates for practical applications in the modern water treatmentindustry.
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