| 1. |
- Nadda, Ashok Kumar, et al.
(författare)
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Chemistry of CO2-phillic materials in enzyme-based hybrid interfacial systems : Implications, strategies and applications
- 2023
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Ingår i: Fuel processing technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 250
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Tidskriftsartikel (refereegranskat)abstract
- Carbon dioxide (CO2) emissions from a variety of sources, such as transportation, fossil fuel burning, and cement manufacturing facilities, are widely regarded to be the root cause of global warming. The rising CO2 levels call for immediate improvements in CO2 capture, extraction, and utilization technology. Methods for capturing and converting CO2 into useful products have included the use of microbial enzymes, nonporous materials, metal -organic frameworks (MOFs), chemicals, and hybrid membranes. However, these methods possess limitations that make the scale up and commercialization challenging. Scientists are concentrating on maximizing CO2 utilization by incorporating CO2-philic components into enzyme-chemical-material combinations, due to the high solubility of CO2. Here, the focus is on the chemistry of CO2-phillic materials, enzymes and biomolecules engaged in CO2 conversion, and the hybrid micro-reactors that contain material and enzymes integrating together to convert the CO2 into value-added products (organic acids, bioelectricity, carbonates, carbamates, methane, methanol, etc.). The difficulties and obstacles inherent in creating and sustaining such systems have also been highlighted.
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| 2. |
- Wainaina, Steven, et al.
(författare)
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Resource recovery and circular economy from organic solid waste using aerobic and anaerobic digestion technologies
- 2020
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976.
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Tidskriftsartikel (refereegranskat)abstract
- With the inevitable rise in human population, resource recovery from waste stream is becoming important for a sustainable economy, conservation of the ecosystem as well as for reducing the dependence on the finite natural resources. In this regard, a bio-based circular economy considers organic wastes and residues as potential resources that can be utilized to supply chemicals, nutrients, and fuels needed by mankind. This review explored the role of aerobic and anaerobic digestion technologies for the advancement of a bio-based circular society. The developed routes within the anaerobic digestion domain, such as the production of biogas and other high-value chemicals (volatile fatty acids) were discussed. The potential to recover important nutrients, such as nitrogen through composting, was also addressed. An emphasis was made on the innovative models for improved economics and process performance, which include co-digestion of various organic solid wastes, recovery of multiple bio-products, and integrated bioprocesses.
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| 3. |
- Ademuyiwa, Adesoji O., et al.
(författare)
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Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
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Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
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| 4. |
- Duan, Yumin, et al.
(författare)
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Succession of keratin-degrading bacteria and associated health risks during pig manure composting
- 2020
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Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 258
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Tidskriftsartikel (refereegranskat)abstract
- The alteration of microbial dynamics and their divergence were evaluated in bristles containing pig manure (PM) compost with different concentrations of coconut shell biochar [0% (T1), 2.5% (T2), 5.0% (T3), 7.5% (T4) and 10% (T5)] amendment. The results revealed that the CB amendment significantly increased the keratin degradation efficiency and bacterial diversity during composting. The richest bacterial diversity and the highest keratin reduction of 39.1% were observed in the PM compost with a 7.5% CB amendment. The most abundant phyla were Firmicutes and Actinobacteria (which accounted for 87.91% and 12.09%, respectively), and the superior genera were Bacilli and Clostridia (which accounted for 23.52% and 61.17%, respectively). In addition, a dimensionality analysis from principal coordinate’s analysis and non-metric multidimensional scaling showed that the bacterial community had a significant divergence among the different dosages of CB. Furthermore, the correlation found in a canonical correspondence analysis illustrated that the physio-chemical environmental factors were more relevant for the bacterial community within the CB in the compost than in that in the control sample. Overall, the application of biochar for composting altered the typical selectivity for functional bacteria and further influenced the organic waste biotransformation during bristle-containing PM composting. (C) 2020 Elsevier Ltd. All rights reserved.
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| 5. |
- Garlapati, Vijay Kumar, et al.
(författare)
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Invasive weed optimization coupled biomass and product dynamics of tuning soybean husk towards lipolytic enzyme.
- 2022
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 344:Pt B
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Tidskriftsartikel (refereegranskat)abstract
- Waste to the product approach was proposed for tuning environ-threat soybean husk towards lipolytic enzyme by integrating the invasive weed optimization with biomass and product dynamics study. The invasive weed optimization constitutes based on the non-linear regression model results in a 47 % enhancement in lipolytic enzyme using the optimization parameters of 7% Sigma Final, 9% exponent; Smax of 5 with a population size of 35 and Max. generations of 99. The biomass dynamic study showcases the dynamic parameters of 0.0239 µmax, 8.17 XLimst and 0.852 RFin values. The product dynamic studies reveal the kinetic parameters of kst, kdiv, PFin, which seem to be equal to -0.0338, 0.0896 and 68.1, respectively. Overall, the present study put forth the zero-waste (soybean husk) to the product (lipolytic enzyme) approach by introducing the novel "Invasive Weed Optimization" coupled with "Biomass and product dynamics" to the bioprocessing field.
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| 6. |
- Mukesh Kumar, Awasthi, et al.
(författare)
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Biotechnological strategies for bio-transforming biosolid into resources toward circular bio-economy : A review
- 2022
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 156
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Forskningsöversikt (refereegranskat)abstract
- Biosolids are the biological organic matter extracted from various treatment processes of wastewater which are considered as a rich source of energy and nutrients. The most commonly used method for the disposal of biosolids is landfilling. But this causes the loss of valuable nutrients and creates environmental issues. Circular economy approaches provide a better way for utilization these resources in a sustainable manner. This allows maximum utilization of resources and many natural resources can be preserved and utilized for future generations. The present review provides a comprehensive illustration of biotechnological approaches for the utilization of biosolids. Various process strategies for the utilization of biosolids for the production of energy, fuels and valueadded products are discussed. The utilization of this rich organic matter under circular economy has also been described in detail.
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| 7. |
- Fulmali, Abhinav Omprakash, et al.
(författare)
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Water diffusion kinetics study at different hydrothermal bath temperatures and subsequent durability studies of CNT embedded fibrous polymeric composites: Roles of CNT content, functionalization and in‐situ testing temperature
- 2023
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 140:11
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Tidskriftsartikel (refereegranskat)abstract
- Although structural polymers like epoxy are extensively used in marine applications over metallic structures, environmental water tends to ingress into this polymer which may affect its long-term durability. The extent of degradation caused by the absorbed water on polymeric composite's mechanical properties depends on the water diffusion mechanism, environmental temperature and subsequent reversible and irreversible chemical restructuring of the polymer. In this study, hydrothermal conditioning behavior of glass fiber reinforced epoxy (GE) composites with varying (0.1, 0.3, and 0.5) wt.% of pristine and functionalized carbon nanotubes (CNTs and FCNTs) was studied at 15°C (Low-Temperature Hydrothermal Conditioning (LTHC)) and 50°C (Elevated-Temperature Hydrothermal Conditioning (ETHC)) water baths. The changes in chemical bonding characteristics and glass transition temperature of GE composite due to above mentioned factors have been studied by Fourier transformed infrared spectroscopy and differential scanning calorimetry. The gravimetric analysis was employed to monitor the water uptake kinetics of the composites and flexural strength of conditioned composites after 50 days of conditioning and saturation was study to understand the effect of water sorption. Experimental results revealed that, FCNTs greatly hinders the water absorption through the interfaces at LTHC, as the equilibrium water content of 0.1FCNT-GE composite was ~9.5% and ~3.0% and Diffusion coefficient was ~60.0% and ~15.5% lower than the GE and 0.1CNT-GE composites, respectively at LTHC. At LTHC, the water saturated 0.1FCNT-GE composites exhibited superior flexural strength than GE and 0.1CNT-GE composites. At ETHC, generation of hygroscopic stresses and unfavorable stresses at the weak CNT/polymer interface adversely affected the 0.1CNT-GE composites water resistance compared to 0.1FCNT-GE composites with stronger FCNT/polymer interface. The extent of recovery in the flexural strength was evaluated by complete desorption of water-saturated specimens. Finally, a fractography study was conducted to understand the variation in the well-being of the glass fiber/polymer and nanotube/polymer interface due to mentioned varying factors.
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| 8. |
- Kasliwal, Mansi M., et al.
(författare)
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Kilonova Luminosity Function Constraints Based on Zwicky Transient Facility Searches for 13 Neutron Star Merger Triggers during O3
- 2020
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 905:2
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Tidskriftsartikel (refereegranskat)abstract
- We present a systematic search for optical counterparts to 13 gravitational wave (GW) triggers involving at least one neutron star during LIGO/Virgo's third observing run (O3). We searched binary neutron star (BNS) and neutron star black hole (NSBH) merger localizations with the Zwicky Transient Facility (ZTF) and undertook follow-up with the Global Relay of Observatories Watching Transients Happen (GROWTH) collaboration. The GW triggers had a median localization area of 4480 deg(2), a median distance of 267 Mpc, and false-alarm rates ranging from 1.5 to 10(-25) yr(-1). The ZTF coverage in the g and r bands had a median enclosed probability of 39%, median depth of 20.8 mag, and median time lag between merger and the start of observations of 1.5 hr. The O3 follow-up by the GROWTH team comprised 340 UltraViolet/Optical/InfraRed (UVOIR) photometric points, 64 OIR spectra, and three radio images using 17 different telescopes. We find no promising kilonovae (radioactivity-powered counterparts), and we show how to convert the upper limits to constrain the underlying kilonova luminosity function. Initially, we assume that all GW triggers are bona fide astrophysical events regardless of false-alarm rate and that kilonovae accompanying BNS and NSBH mergers are drawn from a common population; later, we relax these assumptions. Assuming that all kilonovae are at least as luminous as the discovery magnitude of GW170817 (-16.1 mag), we calculate that our joint probability of detecting zero kilonovae is only 4.2%. If we assume that all kilonovae are brighter than -16.6 mag (the extrapolated peak magnitude of GW170817) and fade at a rate of 1 mag day(-1) (similar to GW170817), the joint probability of zero detections is 7%. If we separate the NSBH and BNS populations based on the online classifications, the joint probability of zero detections, assuming all kilonovae are brighter than -16.6 mag, is 9.7% for NSBH and 7.9% for BNS mergers. Moreover, no more than <57% (<89%) of putative kilonovae could be brighter than -16.6 mag assuming flat evolution (fading by 1 mag day(-1)) at the 90% confidence level. If we further take into account the online terrestrial probability for each GW trigger, we find that no more than <68% of putative kilonovae could be brighter than -16.6 mag. Comparing to model grids, we find that some kilonovae must have M-ej M, X-lan > 10(-4), or > 30 degrees to be consistent with our limits. We look forward to searches in the fourth GW observing run; even 17 neutron star mergers with only 50% coverage to a depth of -16 mag would constrain the maximum fraction of bright kilonovae to <25%.
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| 9. |
- Kumar, A. Naresh, et al.
(författare)
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Upgrading the value of anaerobic fermentation via renewable chemicals production : A sustainable integration for circular bioeconomy
- 2022
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 806, part 1
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Forskningsöversikt (refereegranskat)abstract
- The single bioprocess approach has certain limitations in terms of process efficiency, product synthesis, and effective resource utilization. Integrated or combined bioprocessing maximizes resource recovery and creates a novel platform to establish sustainable biorefineries. Anaerobic fermentation (AF) is a well-established process for the transformation of organic waste into biogas; conversely, biogas CO2 separation is a challenging and cost-effective process. Biological fixation of CO2 for succinic acid (SA) mitigates CO2 separation issues and produces commercially important renewable chemicals. Additionally, utilizing digestate rich in volatile fatty acid (VFA) to produce medium-chain fatty acids (MCFAs) creates a novel integrated platform by utilizing residual organic metabolites. The present review encapsulates the advantages and limitations of AF along with biogas CO2 fixation for SA and digestate rich in VFA utilization for MCFA in a closed-loop approach. Biomethane and biohydrogen process CO2 utilization for SA production is cohesively deliberated along with the role of biohydrogen as an alternative reducing agent to augment SA yields. Similarly, MCFA production using VFA as a substrate and function of electron donors namely ethanol, lactate, and hydrogen are comprehensively discussed. A road map to establish the fermentative biorefinery approach in the framework of AF integrated sustainable bioprocess development is deliberated along with limitations and factors influencing for techno-economic analysis. The discussed integrated approach significantly contributes to promote the circular bioeconomy by establishing carbon-neutral processes in accord with sustainable development goals.
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| 10. |
- Kumar Ramamoorthy, Sunil, 1987-, et al.
(författare)
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Functionalization of Carbon Nanotube
- 2021
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Ingår i: Handbook of Carbon Nanotubes. - Cham : Springer. - 9783319706146
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Bokkapitel (refereegranskat)abstract
- One-dimensional carbon nanotubes (CNTs) have outstanding mechanical properties, making them a good candidate for reinforcement application in polymer and fiber-reinforced polymer composites. Superior properties of the CNTs are exploited regularly by reinforcing these nanotubes in a polymer matrix. However, strong Van der Waals interaction energy of tube-tube contact, high electrostatic interaction between the tubes, small tube size, and large surface area of the tubes render CNT dispersion a problematic task. Therefore, to improve its dispersion and alignment in the composite, researchers have developed innovative techniques to strengthen the properties of the composite. For achieving optimum and reproducible mechanical properties in a composite, fine dispersion of CNTs, their alignment, and strong interfacial adhesion with polymer is a demand to be guaranteed. In this chapter, the principles and techniques for uniform dispersion and alignment of CNTs in the polymer and fiber-reinforced polymer composite are discussed.
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| 11. |
- Kumar, Sunil, et al.
(författare)
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Multifunctional ammonium fuel cell using compost as a novel electro-catalyst
- 2018
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 402, s. 221-228
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Tidskriftsartikel (refereegranskat)abstract
- Due to acute ammonium toxicity, it is always desirable to find a cheaper and abundant electro-catalyst other than platinum, iridium oxide, boron diamond etc with a high selectivity and negligible de-activation for its oxidation. Also ammonium is not known for electricity generation except biological nitrification process. So this paper elucidates the studies of compost as a novel electro-catalyst in a ammonium fuel cell configuration. These studies are done by varying type of electrodes & compost as well as ammonium concentration. Bi-polar cyclic voltammetry, electrochemical impedance spectroscopy, temperature dependence, cyclic stability and chronoamperometry techniques are used to study compost. Cow dung based compost is found to show the best electro-catalytic activity. IV measurements are conducted to study power generation in tune with the electro-catalytic activity. Finally, polarization and sustainability measurements are done on a comparatively larger fuel cell to check the size scalability. The results shows that the maximum power density is 108 mW/m(2) and this multifunctional device can be fueled after every 12 h for continuous operation and with negligible de-activation of electro-catalyst. These studies opens a window for doing further advanced research in compost triggered electro-catalysis to make multifunctional fuel cell devices for solving environmental and energy issues together.
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| 12. |
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| 13. |
- Mondal, Riya, et al.
(författare)
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Dynamic Recrystallization and Phase-Specific Corrosion Performance in a Super Duplex Stainless Steel
- 2021
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Ingår i: Journal of materials engineering and performance (Print). - : ASM International. - 1059-9495 .- 1544-1024.
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Tidskriftsartikel (refereegranskat)abstract
- Super duplex stainless steel specimens were subjected to controlled (in a deformation simulator) thermal and thermal plus deformation treatments. The objective was to relate the corrosion performance with hot (1000-1300°C) deformed microstructures. The microstructural evolutions were quantified with extensive microtextural characterization and measurements of phase-specific micro-hardness. The corrosion behavior was investigated by anodic polarization and phase-specific selective dissolution methods. Though the thermal treatment imposed an increasing degradation in corrosion performance with holding temperature, the associated deformation at that temperature brought a non-monotonic behavior. The best corrosion performance (or the lowest passivation current density) was noted in the specimen deformed at ~1100°C. This superior corrosion behavior was attributed to the grain size refinement in the austenite phase. Finally, a combination of transmission Kikuchi diffraction (TKD) plus transmission electron microscopy (TEM) clearly related the grain size refinement to discontinuous dynamic recrystallization. The overall corrosion behavior was shown to be determined by a balance between decreasing austenite fraction and dynamic recrystallization-induced grain size refinement of the austenite phase.
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| 14. |
- Mukesh Kumar, Awasthi, et al.
(författare)
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Metagenomics for taxonomy profiling : tools and approaches
- 2020
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Ingår i: Bioengineered. - : Taylor & Francis. - 2165-5979 .- 2165-5987. ; 11:1, s. 356-374
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Tidskriftsartikel (refereegranskat)abstract
- The study of metagenomics is an emerging field that identifies the total genetic materials in an organism along with the set of all genetic materials like deoxyribonucleic acid and ribose nucleic acid, which play a key role with the maintenance of cellular functions. The best part of this technology is that it gives more flexibility to environmental microbiologists to instantly pioneer the immense genetic variability of microbial communities. However, it is intensively complex to identify the suitable sequencing measures of any specific gene that can exclusively indicate the involvement of microbial metagenomes and be able to advance valuable results about these communities. This review provides an overview of the metagenomic advancement that has been advantageous for aggregation of more knowledge about speci?c genes, microbial communities and its metabolic pathways. More speci?c drawbacks of metagenomes technology mainly depend on sequence-based analysis. Therefore, this ‘targeted based metagenomics’ approach will give comprehensive knowledge about the ecological, evolutionary and functional sequence of significantly important genes that naturally exist in living beings either human, animal and microorganisms from distinctive ecosystems.
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| 15. |
- Ramamoorthy, Sunil Kumar, et al.
(författare)
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Biocomposites From Regenerated Cellulose Textile Fibers And Bio-Based Thermoset Matrix For Automotive Applications
- 2013
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Konferensbidrag (refereegranskat)abstract
- Biocomposites were produced from regenerated cellulose fiber reinforcement and soybean based bio-matrix. Mechanical, thermal, viscoelastic and morphological results show the good potential of these composites to be used as structural materials in automotive industries. This article focuses on manufacturing and testing of these composites for engineering materials. Regenerated cellulose fibers such as Lyocell and viscose were reinforced in soybean based thermoset matrix to produce composites by compression molding. Hybrid composites were produced by mixing both these fibers at known ratio and the total fiber content in composite was between 40 and 60 weight %. In general, Lyocell based composites showed better tensile properties than viscose based composites. Composites consisting 60 weight % Lyocell and rest with matrix had tensile strength of 135 MPa and tensile modulus of 17 GPa. These composites also showed good flexural properties; flexural strength of 127 Mpa and flexural modulus of 7 GPa. Dynamic mechanical thermal analysis showed that these composites had good viscoelastic properties. Viscose based composites had better percentage elongation during tensile test. These composites also showed relatively good impact and viscoelastic properties. Scanning electron microscope images showed that the composites had good fiber-matrix adhesion. Several efforts are made to produce sustainable biomaterials to replace synthetic materials due to inherent properties like renewable, biodegradable and low density. Biocomposites play significant role in sustainable materials which has already found applications in automotive and construction industries. Many researchers produced biocomposites from natural fiber and bio-based/synthetic matrix and it had found several applications. There are several disadvantages of using natural fiber in composites; quality variation, place dependent, plant maturity, harvesting method, high water absorption etc. These composites also give odor which has to be avoided in indoor automotive applications. These natural fibers can be replaced with lignocelluloses, agro mass and biomass to develop biocomposites as they are from natural origin. Lyocell and viscose are manmade regenerated cellulose fibers which is from natural origin has excellent properties. These fibers can be used as reinforcements to produce biocomposites which can overcome most of the above listed disadvantages of natural fibers. Many composites were made from natural fiber reinforcement and petroleum based synthetic matrix. Researchers have been finding ways to get matrix out of natural resources like soybean and linseed on chemical modifications. This article is focused on producing and testing sustainable material with regenerated cellulose and soybean based bio-matrix for automotive applications.
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| 16. |
- Ramamoorthy, Sunil Kumar, et al.
(författare)
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Characterization Of Wood Based Fiber Reinforced Bio-Composites
- 2013
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Konferensbidrag (refereegranskat)abstract
- Natural fiber composites have got more focus in recent times due to their intrinsic properties such as lightweight, biodegradable, low cost etc. Several researchers have made bio-composites out of many natural fibers such as jute, flax, sisal. These composites have large market in Europe and North America where it is used in automobile and construction industry. A lot of research has been done to improve the properties such as surface modification of fiber, manufacturing hybrid composites. However, the natural fibers are dissimilar and vary largely due to many factors such as variety, harvest, maturity, climate etc. Apart from technical drawbacks, these fibers grow only in certain countries such as India and China. High demand raised the price of these fibers which increases the product price as well. Wood-based fibers such as Lyocell and Viscose was used to make composites in order to make less variation in products, decrease the dependency of natural fibers, promoting locally available fibers and encourage forest products as value-added products. Lyocell and viscose fibers have relatively less variation and high quality. Bio-composites were made by reinforcing wood-based fibers in soybean based thermoset matrix. Hybrid composites were prepared by mixing two different wood-based fibers in known ratio. The fiber content in the composites was between 40 and 60 weight%. Mechanical properties were characterized by tensile, flexural and impact tests. Lyocell and viscose based composites had better mechanical properties than jute fiber composites. Alkali treatment of Lyocell fibers improved the mechanical properties of the composites. The behaviour of wood-based fiber composites were studied under wet environment as well. In wet environment, the mechanical properties of wood-based fiber composites were superior to jute fiber composites. Lyocell based composites had tensile strength of 135 MPa and tensile modulus of 17 GPa. The composites had flexural strength of 127 MPa and flexural modulus of 7 GPa. Better percentage elongation was obtained when viscose fiber was reinforced in matrix. Viscose composites had better impact strength and viscoelastic properties. The change in properties in two different wood-based fibers (Lyocell and viscose) lies in the morphology of the fiber itself. Hybrid composites were produced and the effect of hybridization was clear in most of the cases. The properties were able to be tailored by making hybrid composites, by changing the amount of each fiber in the composites. The results (tensile and flexural) were competitive and fulfil the requirements of these composites to be used in several applications including automotive headliners, car door panel, construction door frame etc. The forest products such as wood fibers could be used in composites to produce environmentally friendly products and promote forest industry. Wood-based fibers such as Lyocell and Viscose was used to make composites in order to make less variation in products, decrease the dependency of natural fibers, promoting locally available fibers and encourage forest products. Bio-composites were made by reinforcing wood-based fibers in soybean based thermoset matrix. Hybrid composites were prepared by mixing two different wood-based fibers in known ratio. Mechanical properties were characterized by tensile, flexural and impact tests. Lyocell and viscose based composites had better mechanical properties than jute fiber composites. Alkali treatment of Lyocell fibers improved the mechanical properties of the composites. The behaviour of wood-based fiber composites were studied under wet environment as well. In wet environment, the mechanical properties of wood-based fiber composites were superior to jute fiber composites. Lyocell based composites had tensile strength of 135 MPa and tensile modulus of 17 GPa. The composites had flexural strength of 127 MPa and flexural modulus of 7 GPa. Viscose composites had better impact strength and viscoelastic properties. The result fulfils the requirements of these composites to be used in several applications including automotive headliners, car door panel etc. The forest products could be used in composites to produce environmentally friendly products and promote forest industry.
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| 17. |
- Ramamoorthy, Sunil Kumar, et al.
(författare)
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Green Composites Based On Regenerated Cellulose Textile Fibers For Structural Composites
- 2013
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Konferensbidrag (refereegranskat)abstract
- Composites were manufactured from regenerated cellulose and biobased matrix by compression molding. The reinforcing materials used were Lyocell and viscose, while the matrix used was chemically modified soybean oil. Hybrid composites were prepared by mixing both the fibers. The total fiber content in the composites was between 40-60 weight %. Lyocell based composites had better tensile properties than viscose based composites; composites consisting 60 weight % Lyocell impregnated with matrix had tensile strength of 135 MPa and tensile modulus of 17 GPa. These composites also showed better flexural properties; flexural strength of 127 MPa and flexural modulus of 7 GPa. Dynamic mechanical thermal analysis results showed that these composites had good viscoelastic properties. Viscose based composites had better percentage elongation; these composites also showed relatively good impact and viscoelastic properties. Hybrid composites showed good mechanical and viscoelastic properties. Scanning electron microscope images showed that the composites had good fiber-matrix adhesion.
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| 18. |
- Ramamoorthy, Sunil Kumar, et al.
(författare)
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Properties of green composites with regenerated cellulose fiber and soybean-based thermoset for technical applications
- 2014
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Ingår i: Journal of reinforced plastics and composites (Print). - : SAGE. - 0731-6844 .- 1530-7964. ; 33:2, s. 193-201
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Tidskriftsartikel (refereegranskat)abstract
- Composites were developed by reinforcing available non-woven Lyocell and viscose in acrylated epoxidized soybean oil (AESO). Compression molding was used to make composites with 40–60 wt% fiber content. The fiber content comprises only Lyocell or viscose fiber, or mixture of these fibers in known ratio. Hybrid composites were made by a mixture of both the fibers in known ratio and it affects the properties. The effect of hybridization was evident in most tests which gives us an opportunity to tailor the properties according to requirement. Lyocell fiber reinforced composites with 60 wt% fiber content had a tensile strength and modulus of about 135 MPa and 17 GPa, respectively. Dynamic mechanical analysis showed that the Lyocell fiber reinforced composites had good viscoelastic properties. The viscose fiber reinforced composites had the high percentage elongation and also showed relatively good impact strength and flexural modulus. Good fiber-matrix adhesion reflected in mechanical properties. SEM images were made to see the fiber-matrix compatibility.
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| 19. |
- Ramamoorthy, Sunil Kumar, et al.
(författare)
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Regenerated Cellulose Fiber Reinforced Composites
- 2013
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Konferensbidrag (refereegranskat)abstract
- Wood pulp based regenerated cellulose fibers like Lyocell and viscose which are from natural origin have high and even quality; used to develop superior composites with good properties. In this project, Lyocell and viscose fibers were reinforced in chemically modified soybean based bio-matrix, acrylated epoxidized soybean oil (AESO) by compression molding technique. The composites are characterized for mechanical performance by tensile, flexural and impact tests, viscoelastic performance by dynamical mechanical thermal analysis (DMTA) and morphological analysis by scanning electron microscopy (SEM). In general, Lyocell composites had better tensile and flexural properties than viscose based composites. The same goes with elastic and viscous response of the composites. Hybrid composites were formed by fiber blending; on addition of Lyocell to viscose based composites improved the properties. The amount of Lyocell and viscose fibers used determined the properties of hybrid composites and the possibility of tailoring properties for specific application was seen. Hybrid composites showed better impact strength. Morphological analysis showed that the viscose composites had small fiber pull out whereas Lyocell composites had few pores. Hybrid composite analysis showed that they had uneven spreading of matrix; delamination occurred on constant heating and cooling. To overcome the above mentioned issue and to reduce the water absorption, surface modification of the fiber was done by alkali treatment and silane treatment. The effect of treatment is done through swelling, water absorption and morphological analysis tests. The properties could be increased on proper modification of the fibers. The results show the good potential of these composites to be used in automotives and construction industries.
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| 20. |
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- 2017
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:2
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Tidskriftsartikel (refereegranskat)
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| 21. |
- Akbari, Samira, et al.
(författare)
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Novel Bio-based Branched Unsaturated Polyester Resins for High-Temperature Applications
- 2023
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Ingår i: Journal of Polymers and the Environment. - 1566-2543 .- 1572-8919.
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Tidskriftsartikel (refereegranskat)abstract
- Unsaturated polyester resins, one of the most important thermosets, are invariably produced from oil-based monomers. Their application is limited in areas where high thermal stability is required due to their low Tg. Besides, these resins contain 30–40% hazardous styrene as a reactive solvent. Therefore, developing bio-based solventless unsaturated polyester resin with medium to high thermomechanical properties compared to petrochemical-based counterparts is important. In order to achieve this, a series of branched bio-based unsaturated polyester resins were synthesized using bulk polymerization method in two steps. In the first step, four different intermediates were prepared by reacting glycerol (as a core molecule) with either isosorbide (diol), 1,3-propanediol (diol), 2,5-furandicarboxylic acid (saturated diacid), or adipic acid (saturated diacid). In the second step, the branched intermediate was end capped with methacrylic anhydride to introduce reactive sites for cross-linking on the branch ends. The chemical structure of the resins was characterized by 13C-NMR. FT-IR confirmed the polycondensation reaction in the first step and the end functionalization of the resins with methacrylic anhydride in the second step. The effect of 2,5-furandicarboxylic acid and isosorbide on thermomechanical and thermal properties was investigated using dynamic mechanical analysis, differential scanning calorimetry, and thermo-gravimetric analysis. Results indicated that 2,5-furandicarboxylic acid based resins had superior thermomechanical properties compared to a commercial reference unsaturated polyester resin, making them promising resins for high-temperature composite applications. For example, the resin based on 2,5-furandicarboxylic acid and isosorbide and the resin based on 2,5-furandicarboxylic acid and 1,3-propanediol gave glass transition temperatures of 173 °C and 148 °C, respectively. Although the synthesized 2,5-furandicarboxylic acid based resins had higher viscosity (22.7 Pas) than conventional unsaturated polyester (0.4–0.5 Pas) at room temperature, preheated resins can be used for making high-temperature-tolerance fiber-reinforced composite.
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| 22. |
- Anjum, Misbah, et al.
(författare)
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A framework for optimal patch release time using G-DEMATEL and multi-attribute utility theory
- 2024
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Ingår i: International Journal of Industrial and Systems Engineering. - : Inderscience Publishers. - 1748-5037 .- 1748-5045. ; 46:4, s. 531-555
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Tidskriftsartikel (refereegranskat)abstract
- The primary focus of the present work is to determine the optimal vulnerability patch release time using multi-attribute utility theory (MAUT) by considering two objectives that are cost minimisation and reliability maximisation. The novelty of the study lies in multi-phased research methodology for identifying the attributes affecting the software patch release time through a combination of literature review and the grey-Delphi approach for guiding the optimisation process. The literature has directly considered the weights of the attributes without emphasising their interrelationships, which is overcome by the use of the DEMATEL methodology under the grey environment in the current study for the evaluation of weights of selected attributes. The implications of the study will help in achieving the sustainable development goals pertaining to innovation and infrastructure. A numerical example is used to demonstrate the relevance of the optimisation problem.
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| 23. |
- Baghaei, Behnaz, et al.
(författare)
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Hemp/PLA Co-Wrapped Hybrid Yarns For Structured Thermoplastic Composites
- 2013
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Konferensbidrag (refereegranskat)abstract
- In recent years, natural fibre-reinforced polymer composites have been attracting attention from the viewpoint of reducing the impact on the natural environment. Currently, the use of thermoplastic resins in composites is clearly of higher potential than the use of thermoset. There are many thermoplastic polymers derived from renewable raw materials, which are also biodegradable. Polylactic acid (PLA) is one such candidate, and it shows rather good properties that are suitable for applications that do not require long-term durability or elevated mechanical performance at higher temperatures. In order to make their possible use in many technical applications more attractive, the mechanical properties of the PLA can be enhanced by using reinforcements. Hemp fibres can be considered to be a good choice for reinforcing polymer composites, due to their high stiffness, strength, and aspect ratio. Highly ordered textile reinforcements, such as interlaced woven fabrics and unidirectional fabrics made from natural-fibre yarns, perform considerably better than random non-woven mats in natural-fibre composites. At present, the commercially available plant-fibre yarns are not intended for structural composites, but for textiles, which have entirely different demands on the yarns. Thus, work is needed to tailor-make the best plant-fibre yarn for reinforcement of composites. This also includes investigation of the possibility of combining plant-fibre yarns with the matrix polymer in fibre form into one hybrid yarn (a composite preform), and how to do it (twisting or blending). It is well known that fibres provide the highest strength and stiffness when they are continuous and aligned in the direction of the applied load. Natural fibres are naturally discontinuous and conventional spun staple yarns tend to be highly twisted, which leads to fibre misalignment and poor resin wet-out. The structured natural-fibre composites reported so far are based on twisted yarns produced by long-established conventional spinning methods, mainly ring spinning. In this paper, we report our work on improving the orientation of hemp fibres in composites by using our recent development of co-wrapped yarn structures. This novel co-wrapped yarn consists of low twist and very fine hemp yarns next to PLA filaments in the core part, which are wrapped by PLA filaments. By varying the composition of hybrid yarn, it is possible to vary the hemp fibre content from 10 to 45 wt %. An exciting recent advancement has been a new family of aligned natural-fibre reinforcements, which has overcome these issues by using low twist yarns. We also report the influence of fibre content and wrap density (number of wraps per unit length) on the properties of composites. Before compression moulding, multilayer 0/90 bidirectional hybrid yarn prepregs were prepared by winding the hybrid yarn around a steel rectangular frame. We investigated the mechanical and thermo-mechanical properties of hemp-reinforced PLA composites. Compared to neat PLA, the tensile and flexural modulus and the strength of the PLA-hemp composites were significantly higher as a result of the increased fibre content. Impact strength of the composites decreased initially up to 10 wt % fibre loading, but even higher fibre loading caused an improvement in impact strength. From the DMTA results, it is evident that incorporation of the fibres gives a considerable increase in storage modulus and a decrease in tan δ values. These results show the reinforcing effect of hemp on PLA matrix. From the general trend in the results obtained, it can be affirmed that co-wrapped hybrid yarn with lower wrapping density leads to lower mechanical properties in the composite. The study performed with DSC revealed that the glass transition temperature and the crystalline melting point of PLA were not affected significantly after reinforcement with hemp. The crystallisation temperature of the hemp-reinforced PLA composites decreased compared to pure PLA, which indicates that the hemp fibres hinder the migration and diffusion of PLA molecular chains to the surface of the nucleus in the composites. No noteworthy differences in calorimetric data from DSC for composites were observed between the hybrid yarn preforms with different wrapping density. Future work will concentrate on efforts to evaluate the biodegradability of these developing and promising composites.
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| 24. |
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| 25. |
- Bakare, Fatimat O., et al.
(författare)
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Thermomechanical properties of bio-based composites made from a lactic acid thermoset resin and flax and flax/basalt fibre reinforcements
- 2016
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Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier. - 1359-835X .- 1878-5840. ; 83, s. 176-184
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Tidskriftsartikel (refereegranskat)abstract
- Low viscosity thermoset bio-based resin was synthesised from lactic acid, allyl alcohol and pentaerythritol. The resin was impregnated into cellulosic fibre reinforcement from flax and basalt and then compression moulded at elevated temperature to produce thermoset composites. The mechanical properties of composites were characterised by flexural, tensile and Charpy impact testing whereas the thermal properties were analysed by dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The results showed a decrease in mechanical properties with increase in fibre load after 40 wt.% for the neat flax composite due to insufficient fibre wetting and an increase in mechanical properties with increase fibre load up to 60 wt.% for the flax/basalt composite. The results of the ageing test showed that the mechanical properties of the composites deteriorate with ageing; however, the flax/basalt composite had better mechanical properties after ageing than the flax composite before ageing.
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