Search

This article uses experimental methods to measure the operational performance and pollutant emissions of micro gas turbines in different intake environments, and analyzes the feasibility of replacing mine ventilation fans with micro gas turbines. The results show that when the compressor efficiency is increased from 70 % to 90 %, the total efficiency of the micro combustion engine is increased from 28% to 34 %, with an increase of up to 21.4 %. When the demand power is 25 kW, the fluctuation range of NOx emission concentration is within 5.4 %. When the intake opening is below 50 %, the effect is obvious. When the intake opening is reduced from 50 % to 25 %, the performance of the micro gas turbine decreases by 0.7 %; The influence of intake humidity on various operating parameters of micro gas turbines is generally within 3 %, which can meet the requirements of high humidity environment operation; The intake temperature has the greatest impact, with an increase in intake temperature leading to a decrease in power generation efficiency. After comprehensive analysis, we believe that the application of gas turbines in mines is feasible.

The demand for advanced biomaterials in medical treatments is rapidly expanding. To address this demand, a nanocomposite of cellulose nanofiber (CNF) with chitosan (Ch) and graphene oxide (GO) was developed for burn wound treatment. The CNF-Ch-GO nanocomposites were characterized and their biological properties were evaluated. Microscopic images showed a uniform distribution of CNF, Ch, and GO with a porous structure. ATR-FTIR and XRD analyses confirmed the chemical structures, while a thermogravimetric study confirmed the stability of CNF-Ch-GO nanocomposite under a N 2 atmosphere. The synthesized CNF-Ch-GO nanocomposite exhibited rapid absorption, absorbing 1781.7 ± 53.7 % PBS in 2 min. It demonstrated a Young's modulus of 11.90 ± 0.06 MPa in a hydrated condition, indicating its mechanical stability in water. Furthermore, it displayed excellent biocompatibility and hemocompatibility with 96.23 ± 12.21 % cell viability and 0.21 ± 0.08 % of hemolysis. Additionally, the blood clotting index of CNF-Ch-GO was comparable to that of standard dressing gauze. To enhance antimicrobial efficacy, CNF-Ch-GO was conjugated with lysozyme. This biotic and abiotic conjugation resulted in 92.17 % ± 3.02 % and 94.99 ± 2.1 % eradication of Escherichia coli and Staphylococcus aureus, respectively. The enhanced antimicrobial properties, biocompatibility, and mechanical stability of the superabsorbent CNF-Ch-GO nanocomposite indicate its significant potential for advanced burn wound healing applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Deterioration in the environmental ecosystems through the depletion of nonrenewable resources and the burden of deleterious contaminants is considered a global concern. To this end, great interest has been shown in the use of renewable and environmentally-friendly reactive materials dually to promote environmental sustainability and cope with harmful contaminants. Among the different available options, the use of nanocellulose (NC) as an environmentally benign and renewable natural nanomaterial is an attractive candidate for environmental remediation owing to its miraculous physicochemical characteristics. This review discusses the intrinsic properties and the structural aspects of different types of NC, including cellulose nanofibrils (CNFs), cellulose nanocrystals (CNCs), and bacterial cellulose (BC) or bacterial nanocellulose (BNC). Also, the different modification strategies involving the functionalization or hybridization of NC by using different functional and reactive materials aimed at wastewater remediation have been elaborated. The modified or hybridized NC has been explored for its applications in the removal or degradation of aquatic contaminants through adsorption, filtration, coagulation, catalysis, photocatalysis, and pollutant sensing. This review highlights the role of NC in the modified composites and describes the underlying mechanisms involved in the removal of contaminants. The life-cycle assessment (LCA) of NC is discussed to unveil the hidden risks associated with its production to the final disposal. Moreover, the contribution of NC in the promotion of waste management at different stages has been described in the form of the five-Rs strategy. In summary, this review provides rational insights to develop NC-based environmentally-friendly reactive materials for the removal and degradation of hazardous aquatic contaminants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Micro-crimped fibers have been widely used in the field of tissue repair to mimic the natural tissue structure and mechanical properties. However, the electrospun nanofibrous membrane is a kind of dense structure, which cannot meet the requirements of mechanical properties and permeability. In this study, we prepared nanofibrous scaffold with controllable porosity and crimpness by sacrificing fiber components and releasing residual stress. The results show that the crimpness of the fiber is positively related to the porosity, and with the increase of porosity, the fiber crimpness increases greatly. Meanwhile, the scaffold modulus was reduced by 86% and the elongation at break doubled, which is similar to natural blood vessels. Moreover, it is found that the porous micro-crimped fiber scaffold promotes the adhesion and diffusion of endothelial cells, and facilitates the rapid endothelialization of the scaffold, which has a great potential for practical application., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Bacterial-derived extracellular vesicles could play a major role in attenuating and treating diseases. They play a major anti-infection role by modulating immune responses against pathogens and preventing infection by inhibiting pathogen localization and proliferation. In this study, outer membrane vesicles (ExHp-CD) released by Helicobacter pylori SS1 (H. pylori) and total antigens isolated from H. pylori SS1 (AgHp) were evaluated for their immunogenic potential and their effect on macrophage RAW 264.7 cells. Results demonstrated that both ExHp-CD and AgHp induced T helper 2 (Th2) immune response, which was reported to be important in immune protection against H. pylori infections. Both ExHp-CD and AgHp produced high levels of IL-10 and IL-4, while no significant levels of IL-12 p70 or IFN-γ were detected. However, ExHp-CD showed a better effect on macrophage RAW 264.7 cells compared to AgHp. Macrophage RAW 264.7 cells stimulated with 5, and 10 μg/mL of ExHp-CD showed an increased ratio of CD206 (M2 phenotype marker) and a decreased ratio of CD86 (M1 phenotype marker). Moreover, results suggested that the immunogenic effect that ExHp-CD possesses was attributed to their cargo of Epimerase_2 domain-containing protein (Epi_2D), Probable malate:quinone oxidoreductase (Pro_mqo), and Probable cytosol aminopeptidase (Pro_ca). Results demonstrated that ExHp-CD possesses an immunological activity to induce Th2 immune response against H. pylori infection with results comparable to AgHp. However, ExHp-CD showed higher efficacy regarding safety, biocompatibility, lack of toxicity, and hemocompatibility. Thus, it could serve as an immunogenic candidate with more desired characteristics., (Copyright © 2021. Published by Elsevier Inc.)

The current study was aimed to develop a transparent wound dressing comprised of bacterial cellulose (BC) and poly (2-hydroxyethyl methacrylate) (PHEMA) hydrogel coated with silver (Ag) nanoparticles. Briefly, different concentrations of BC whiskers (BCWs) were added into the HEMA solution to form PHEMA/BCWs hydrogel with volume ratio of monomer HEMA and BCWs as 7:3 and 1:1. The addition of BCWs into PHEMA matrix improved its equilibrium water content and light transmittance about 20%-40% and 10%, respectively. The Young's modulus for PHEMA was found to be 0.72MPa, which was improved to 0.57MPa and 0.50MPa for PHEMA/BCWs 7:3 and PHEMA/BCWs 1:1, respectively. Further, immersion of PHEMA/BCWs hydrogel in the AgNO 3 and NaBH 4 solutions bestowed it with antibacterial property and produced inhibition zones of 0.5±0.15cm and 0.25±0.15cm against Escherichia coli and Staphylococcus aureus, respectively. Similarly, PHEMA/BCWs prepared with 0.001M AgNO 3 and 0.001M NaBH 4 solutions showed 99% and 90% reduction in colony forming unit (CFU) for E. coli and S. aureus, respectively, after 24h. The PHEMA/BCWs/Ag hydrogel facilitated the growth of NIH3T3 fibroblast, showing their low toxicity. These results demonstrate the suitability of PHEMA/BCWs/Ag hydrogel for its application as potential transparent wound dressing material for skin repair., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This work presents a numerical-experimental framework for assessment of stiffness of nanofibres in a fibrous hydrogel - bacterial cellulose (BC) hydrogel - based on a combination of in-aqua mechanical testing, microstructural analysis and finite-element (FE) modelling. Fibrous hydrogels attracted growing interest as potential replacements to some tissues. To assess their applicability, a comprehensive understanding of their mechanical response under relevant conditions is desirable; a lack of such knowledge is mainly due to changes at microscale caused by deformation that are hard to evaluate in-situ because of the dimensions of nanofibres and aqueous environment. So, discontinuous FE simulations could provide a feasible solution; thus, properties of nanofibres could be characterised with a good accuracy. An alternative - direct tests with commercial testing systems - is cumbersome at best. Hence, in this work, a numerical-experimental framework with advantages of convenience and relative easiness in implementation is suggested to determine the stiffness of BC nanofibres. The obtained magnitudes of 53.7-64.9GPa were assessed by calibrating modelling results with the original experimental data., (Copyright © 2017. Published by Elsevier B.V.)

Biological hydrogels, e.g. bacterial cellulose (BC) hydrogel, attracted increasing interest in recent decades since they show a good potential for biomedical engineering as replacements of real tissues thanks mainly to their good biocompatibility and fibrous structure. To select potential candidates for such applications, a comprehensive understanding of their performance under application-relevant conditions is needed. Most hydrogels demonstrate time-dependent behaviour due to the contribution of their liquid phase and reorientation of fibres in a process of their deformation. To quantify such time-dependent behaviour is crucial due to their exposure to complicated loading conditions in body environment. Some hydrogel-based biomaterials with a multi-layered fibrous structure demonstrate a promise as artificial skin and blood vessels. To characterise and model time-dependent behaviour of these multi-layered hydrogels along their through-thickness direction is thereby of vital importance. Hence, a holistic study combining mechanical testing and micro-morphological observations of BC hydrogel with analytical modelling of its relaxation behaviour based on fraction-exponential operators was performed. The results show a good potential to use a fraction-exponential model to describe such behaviour of multi-layered hydrogels, especially at stages of stress decay at low forces and of stress equilibrium at high forces., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

This study is focused on anomalous strain-rate-dependent behaviour of bacterial cellulose (BC) hydrogel that can be strain-rate insensitive, hardening, softening, or strain-rate insensitive in various ranges of strain rate. BC hydrogel consists of randomly distributed nanofibres and a large content of free water; thanks to its ideal biocompatibility, it is suitable for biomedical applications. Motivated by its potential applications in complex loading conditions of body environment, its time-dependent behaviour was studied by means of in-aqua uniaxial tension tests at constant temperature of 37 °C at various strain rates ranging from 0.000 1s(-1) to 0.3s(-1). Experimental results reflect anomalous strain-rate-dependent behaviour that was not documented before. Micro-morphological observations allowed identification of deformation mechanisms at low and high strain rates in relation to microstructural changes. Unlike strain-rate softening behaviours in other materials, reorientation of nanofibres and kinematics of free-water flow dominate the softening behaviour of BC hydrogel at high strain rates., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This work focuses on time-dependent rheological behaviour of bacterial cellulose (BC) hydrogel. Due to its ideal biocompatibility, BC hydrogel could be employed in biomedical applications. Considering the complexity of loading conditions in human body environment, time-dependent behaviour under relevant conditions should be understood. BC specimens are produced by Gluconacetobacter xylinus ATCC 53582 at static-culture conditions. Time-dependent behaviour of specimens at several stress levels is experimentally determined by uniaxial tensile creep tests. We use fraction-exponential operators to model the rheological behaviour. Such a representation allows combination of good accuracy in analytical description of viscoelastic behaviour of real materials and simplicity in solving boundary value problems. The obtained material parameters allow us to identify time-dependent behaviour of BC hydrogel at high stress level with sufficient accuracy., (Copyright © 2015 Elsevier B.V. All rights reserved.)