Hasil untuk "Chemical technology"

Qiwei Zhang, Yicheng Wang, Jiayuan Wei et al.

Hydrogen energy, as a pivotal secondary energy carrier for the future, plays a core role in achieving global carbon neutrality goals through its green production. Currently, water electrolysis for hydrogen production, particularly alkaline water electrolysis, is regarded as the primary pathway for green hydrogen generation due to its technological maturity and cost‐effectiveness. However, this technology still faces challenges such as low operating current density, high energy consumption, and the difficulty in balancing the activity and stability of nonprecious metal catalysts under high current densities. The design of traditional electrocatalysts has reached a bottleneck, making breakthrough progress difficult. Therefore, this review focuses on internal and external field‐assisted water electrolysis strategies, systematically summarizing the latest research advances in field regulation for enhancing electrocatalytic performance. These strategies provide innovative approaches to addressing the energy efficiency and cost challenges in water electrolysis for hydrogen production, demonstrating the significant potential of field regulation in driving the development of next‐generation, high‐performance, and highly stable water electrolysis technologies.

Kim-Marie A. Dam, Harry B. Gristick, Yancheng E. Li et al.

Summary: HIV-1 broadly neutralizing antibodies (bNAbs) targeting the CD4-binding site (CD4bs) contain rare features that pose challenges to elicit these bNAbs through vaccination. The IOMA class of CD4bs bNAbs includes fewer rare features and somatic hypermutations (SHMs) to achieve broad neutralization, thus presenting a potentially accessible pathway for vaccine-induced bNAb development. Here, we created a library of IOMA variants in which each SHM was individually reverted to the inferred germline counterpart to investigate the roles of SHMs in conferring IOMA’s neutralization potency and breadth. Impacts on neutralization for each variant were evaluated, and this information was used to design minimally mutated IOMA-class variants (IOMAmin) that incorporated the fewest SHMs required for achieving IOMA’s neutralization breadth. A cryoelectron microscopy (cryo-EM) structure of an IOMAmin variant bound to Env was used to further interpret characteristics of IOMA variants to elucidate how IOMA’s structural features correlate with its neutralization mechanism, informing the design of IOMA-targeting immunogens.

Na Song, Huili Xia, Yaoru Xie et al.

Tyrosol is an important component of pharmaceuticals, nutraceuticals, and cosmetics, and their biosynthetic pathways are currently a hot research topic. d-Erythrose 4-phosphate is a key precursor for the biosynthesis of tyrosol in Saccharomyces cerevisiae. Hence, the flux of d-Erythrose 4-phosphate determined the yield of tyrosol synthesis. In this study, we first obtained an S. cerevisiae strain S19 with a tyrosol yield of 247.66 mg/L by metabolic engineering strategy. To increase the production of d-Erythrose 4-phosphate, highly active phosphoketolase BA-C was obtained by bioinformatics combined with tyrosol yield assay. The key residue sites 183, 217, and 320 were obtained by molecular docking, kinetic simulation, and tyrosol yield verification. After mutation, the highly efficient phosphoketolase BA-CHis320Met was obtained, with a 37.32 % increase in enzyme activity. The tyrosol production of strain S26 with BA-CHis320Arg increased by 43.05 % than strain S25 with BA-C and increased by 151.19 % compared with the strain S19 without phosphoketolase in a 20 L fermenter. The mining and modification of phosphoketolase will provide strong support for the de novo synthesis of aromatic compounds.

ZHANG Lei, YU Ying, ZHAO Yixuan, CHEN Qiang, YANG Ruxing

This study aimed to evaluate the dynamic changes of non-volatile metabolites during green tea processing from the albino tea variety ‘Fuhuang 1’. Green tea was made from one bud with two leaves through three steps: natural drying, fixation and rolling. A total of 2 654 non-volatile metabolites were detected by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) in the raw material, intermediate products and final product. The total content of non-volatile metabolites showed an upward trend during tea processing. Our analysis showed that fixation was crucial for the conversion of non-volatile metabolites in green tea processing. A total of 292 important differential metabolites were selected before and after fixation, including amino acids and their derivatives (40), flavonoids (37), lipids (101), nucleotides and their derivatives (28), and phenolic acids (21). These metabolites were significantly enriched in pathways such as the biosynthesis of secondary metabolites, carbon metabolism, cysteine and methionine metabolism, arginine biosynthesis, alanine, aspartic acid and glutamic acid metabolism. They were categorized into three clusters by K-Means analysis. The metabolites in the first cluster accumulated significantly during fixation. The metabolites in the second cluster accumulated significantly during fixation and also accumulated during drying, but to a lesser extent. However, the metabolites in the third cluster significantly decreased during fixation. Amino acids and their derivatives accumulated significantly during fixation, especially reduced glutathione, which might be a signature compound of ‘Fuhuang 1’ green tea. Lipids were the most active compounds during green tea processing; their relative contents significantly increased, with lysophosphatidylethanolamine showing the greatest accumulation. Some flavonoids, nucleotides and their derivatives accumulated only during fixation, whereas others accumulated during both fixation and drying. This study provides a theoretical basis for the innovative utilization of tea albino mutants.

Annamarija Trausa, Sven Oras, Sergei Vlassov et al.

Due to the recent interest in ultrawide bandgap β-Ga2O3 thin films and nanostructures for various electronics and UV device applications, it is important to understand the mechanical properties of Ga2O3 nanowires (NWs). In this work, we investigated the elastic modulus of individual β-Ga2O3 NWs using two distinct techniques – in-situ scanning electron microscopy resonance and three-point bending in atomic force microscopy. The structural and morphological properties of the synthesised NWs were investigated using X-ray diffraction, transmission and scanning electron microscopies. The resonance tests yielded the mean elastic modulus of 34.5 GPa, while 75.8 GPa mean value was obtained via three-point bending. The measured elastic moduli values indicate the need for finely controllable β-Ga2O3 NW synthesis methods and detailed post-examination of their mechanical properties before considering their application in future nanoscale devices.

Lars Bippus, Ann-Kathrin Briem, Ann-Kathrin Briem et al.

Introduction: This study assesses the environmental impacts of mannosylerythritol lipids (MELs) production for process optimization using life cycle assessment (LCA). MELs are glycolipid-type microbial biosurfactants with many possible applications based on their surface-active properties. They are generally produced by fungi from the family of Ustilaginaceae via fermentation in aerated bioreactors. The aim of our work is to accompany the development of biotechnological products at an early stage to enable environmentally sustainable process optimization.Methods: This is done by identifying hotspots and potentials for improvement based on a reliable quantification of the environmental impacts. The production processes of MELs are evaluated in a cradle-to-gate approach using the Environmental Footprint (EF) 3.1 impact assessment method. The LCA model is based on upscaled experimental data for the fermentation and purification, assuming the production at a 10 m³ scale. In the case analyzed, MELs are produced from rapeseed oil and glucose, and purified by separation, solvent extraction, and chromatography.Results: The results of the LCA show that the provision of substrates is a major source of environmental impacts and accounts for 20% of the impacts on Climate Change and more than 70% in the categories Acidification and Eutrophication. Moreover, 33% of the impacts on Climate Change is caused by the energy requirements for aeration of the bioreactor, while purification accounts for 42% of the impacts respectively. For the purification, solvents are identified as the main contributors in most impact categories.Discussion: The results illustrate the potentials for process optimization to reduce the environmental impacts of substrate requirements, enhanced bioreactor aeration, and efficient solvent use in downstream processing. By a scenario analysis, considering both experimental adaptations and prospective variations of the process, the laboratory development can be supported with further findings and hence efficiently optimized towards environmental sustainability. Moreover, the presentation of kinetic LCA results over the fermentation duration shows a novel way of calculating and visualizing results that corresponds to the way of thinking of process engineers using established environmental indicators and a detailed system analysis. Altogether, this LCA study supports and demonstrates the potential for further improvements towards more environmentally friendly produced surfactants.

T. Shynkaruk, K. Long, C. LeBlanc et al.

SUMMARY: Re-evaluating management practices to highlight opportunities for improving bird welfare is a necessary response to changing genetics, evolving standards, and increasing consumer interest in how poultry is raised. The aim of this study was to evaluate the impact of stocking density (SD) on the welfare and productivity of broilers. The SD treatments were 31, 34.5, 38, and 41.5 kg/m2. Litter moisture decreased and footpad dermatitis improved as SD was reduced, indicating an improvement in welfare. Results from the novel object test suggest birds reared at lower SD were less fearful. Heterophil/lymphocyte ratios were highest in the 31 and 41.5 kg/m2 treatments, indicating these birds experienced more chronic stress. At 20 d as SD was decreased, birds spent more time at the drinker and less time resting. When older (31 d), birds preened more in the 31 and 41.5 kg/m2 treatments. Stretching behavior decreased while ruffling increased at lower SD. Final body weights were heaviest in the 31 and 34.5 kg/m2 treatments. Overall, body weight gain increased as SD was reduced, and feed intake was greatest in the 34.5 kg/m2 treatment. From 21 to 24 d, infectious mortality was reduced in the low SD treatments. The impacts of SD are dependent on environmental management; however, even under research conditions, differences between treatments were observed. The results of this study suggest that reducing SD for broilers results in improved welfare and performance as evidenced by reductions in litter moisture, footpad dermatitis, fear, stress, and infectious mortality as well as greater market body weights and feed consumption.

Yibin Chang, Jian Dai

The Panjian structure is an important longitudinal connecting member of Song Dynasty hall-type buildings in China. To study the lateral force resistance of such structures, a refined finite element model of Song-style hall-type single-room four-column space timber frame containing Panjian structure was established based on the official building code Yingzao Fashi of Song Dynasty. The Panjian and inner E’fang in the lower-ping part, the Panjian in the upper-ping part, and Guazi-gong Panjian and Man-gong Panjian in the roof ridge part were investigated. The model hysteresis curves of all three parts of the longitudinal timber frame were found to be S-shaped, with obvious pinching effect, fuller at both ends and centrosymmetric shape. The Panjian structures in the lower-ping and upper-ping parts, and the Guazi-gong Panjian in the roof ridge part increased the energy dissipation and lateral stiffness of the timber frame. The Man-gong Panjian in the roof ridge part, however, was detrimental to the lateral resistance of the structure. Throughout the test, the Panjian structures were relatively intact, with large plastic damage occurring at both ends of the E’fang. For the repair and testing of similar ancient buildings, some reference suggestions are provided.

Yu WANG, Peiyue ZHAO, Shicheng LEI et al.

In order to clarify the preservation effect of theaflavins-soy protein isolate complex coating on Lentinus edodes, a TFs-SPI complex coating agent was prepared by mixing theaflavins and soy protein isolate as subjects, and its structure was characterized by ultraviolet spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray power diffractometry. Meanwhile, the effect of TFs-SPI complex coating on sensory quality, nutrition indicators and total plate count of fresh Lentinus edodes stored at 4 ℃for 20 d were evaluated. The results showed that TFs and SPI could spontaneously form a stable complex through non-covalent interactions. Ultraviolet spectra demonstrated that the interaction between TFs and SPI caused a red shift in the maximum absorption wavelength of SPI and changed the conformation of SPI. Differential scanning calorimetry and X-ray diffraction analysis indicated that TFs-SPI complex was in the amorphous state. Fourier transform infrared spectra revealed that secondary structure of SPI was changed by TFs. Compared with the control, TFs-coated and SPI-coated groups, Lentinus edodes in the TFs-SPI complex coating group showed significant improvement in several qualities during storage, including slowed down the variations of sensory scores and pH values, reduced weight loss and soluble solids content, improved soluble protein and reducing sugar content, as well as inhibited the growth of bacteria. In conclusion, TFs-SPI complex coating treatment could futher maintain the quality of Lentinus edodes, and prolong their shelf life.

Jie Yu, Yawen Dai, Zhenbao Zhang et al.

Abstract Rational construction of carbon‐based materials with high‐efficiency bifunctionality and low cost as the substitute of precious metal catalyst shows a highly practical value for rechargeable Zn‐air batteries (ZABs) yet it still remains challenging. Herein, this study employs a simple mixing‐calcination strategy to fabricate a high‐performance bifunctional composite catalyst composed of N‐doped graphitic carbon encapsulating Co nanoparticles (Co@NrC). Benefiting from the core‐shell architectural and compositional advantages of favorable electronic configuration, more exposed active sites, sufficient electric conductivity, rich defects, and excellent charge transport, the optimal Co@NrC hybrid (Co@NrC‐0.3) presents outstanding catalytic activity and stability toward oxygen‐related electrochemical reactions (oxygen reduction and evolution reactions, i.e., ORR and OER), with a low potential gap of 0.766 V. Besides, the rechargeable liquid ZAB assembled with this hybrid electrocatalyst delivers a high peak power density of 168 mW cm−2, a small initial discharge‐charge potential gap of 0.45 V at 10 mA cm−2, and a good rate performance. Furthermore, a relatively large power density of 108 mW cm−2 is also obtained with the Co@NrC‐0.3‐based flexible solid‐state ZAB, which can well power LED lights. Such work offers insights in developing excellent bifunctional electrocatalysts for both OER and ORR and highlights their potential applications in metal‐air batteries and other energy‐conversion/storage devices.

XIONG Wen-yu, HE Jun-qiang, DAI Wan-zhen et al.

The main functional components and biological activities of <i>Grifola frondosa</i> were reviewed, and the existing problems and future research directions were also discussed.

Caroline Kniebs, Caroline Kniebs, Anja Elisabeth Luengen et al.

Lung cancer is the most frequently diagnosed cancer worldwide and the one that causes the highest mortality. In order to understand the disease and to develop new treatments, in vitro human lung cancer model systems which imitate the physiological conditions is of high significance. In this study, a human 3D lung cancer model was established that features the organization of a tumor with focus on tumor angiogenesis. Vascular networks were formed by co-culture of human umbilical vein endothelial cells and adipose tissue-derived mesenchymal stem cells (ASC) for 14 days in fibrin. A part of the pre-vascularized fibrin gel was replaced by fibrin gel containing lung cancer cells (A549) to form tri-cultures. This 3D cancer model system was cultured under different culture conditions and its behaviour after treatment with different concentrations of tumor-specific therapeutics was evaluated. The evaluation was performed by measurement of metabolic activity, viability, quantification of two-photon laser scanning microscopy and measurement of the proangiogenic factor vascular endothelial growth factor in the supernatant. Hypoxic conditions promoted vascularization compared to normoxic cultured controls in co- and tri-cultures as shown by significantly increased vascular structures, longer structures with a higher area and volume, and secretion of vascular endothelial growth factor. Cancer cells also promoted vascularization. Treatment with 50 µM gefitinib or 50 nM paclitaxel decreased the vascularization significantly. VEGF secretion was only reduced after treatment with gefitinib, while in contrast secretion remained constant during medication with paclitaxel. The findings suggest that the herein described 3D lung cancer model provides a novel platform to investigate the angiogenic potential of cancer cells and its responses to therapeutics. Thus, it can serve as a promising approach for the development and patient-specific pre-selection of anticancer treatment.

Yi-Shan Cheng, Yi-Shan Cheng, Andy Chien et al.

Degenerative cervical myelopathy (DCM) is a common aging condition caused by spinal cord compression. Individuals with DCM often presented with residual balance and functional impairments postoperatively. Perturbation-based balance training (PBT) has been shown to have positive effects on populations with neurological disorders but has yet to be investigated in DCM. The objective of this study was therefore to evaluate the effects of PBT on balance and functional performance in postoperative individuals with DCM. Fifteen postoperative individuals with DCM (DCM group) and 14 healthy adults (healthy control group) were recruited. The DCM group received a 4-weeks PBT using a perturbation treadmill. The outcome measures included mean velocity of center of pressure (COP) during quiet standing; center of mass (COM) variance and reaction time to balance perturbation during standing with forward and backward perturbation; gait speed during level ground walking; Timed Up and Go Test (TUG) and disability questionnaire scores including Visual Analog Scale, Neck Disability Index, and Lower Extremity Function of Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire. The assessments were conducted pre- and post-training postoperatively for the DCM group but only once for the healthy control group. Significant improvements were observed in the mean velocity of COP, COM variance, reaction time, gait speed, and TUG in the DCM group. Disability questionnaire scores were not significantly different after training in DCM group. For between-group comparisons, significant differences that were observed pre-training were not observed post-training. The 4-weeks PBT is a potential rehabilitation strategy for addressing balance and functional impairment in postoperative individuals with DCM. In addition, the post-training performance in the DCM group exhibited trends comparable to those of age-matched healthy controls. Furthermore, the training regimens offer a practical reference for future studies on populations with balance disorders. Future studies complemented with neurophysiological assessments could reveal more information of the underlying mechanisms of PBT.

Sven Warris, Elio Schijlen, Henri van de Geest et al.

Abstract Background Next-generation sequencing requires sufficient DNA to be available. If limited, whole-genome amplification is applied to generate additional amounts of DNA. Such amplification often results in many chimeric DNA fragments, in particular artificial palindromic sequences, which limit the usefulness of long sequencing reads. Results Here, we present Pacasus, a tool for correcting such errors. Two datasets show that it markedly improves read mapping and de novo assembly, yielding results similar to these that would be obtained with non-amplified DNA. Conclusions With Pacasus long-read technologies become available for sequencing targets with very small amounts of DNA, such as single cells or even single chromosomes.

Clement Chanut, Frederic Heymes, Pierre Lauret et al.

Metallic dust explosion is a challenging research topic. One key point of investigation is the flame propagation velocity, which can be determined experimentally by direct visualization of the explosions. This paper presents the results of flame propagation during an aluminum dust explosion inside a vertical prototype of 700 mm height and 150x150 mm square cross section, with glass walls. The study considers direct visualization: the light emitted by the aluminum flame is recorded with a fast camera. Aluminum flames look white and highly luminous. A special attention is therefore requested to collect images without saturation. Indeed, aluminum flame images from literature are mostly saturated; therefore comparison of images obtained with and without saturation is of high interest. The flame propagation velocity, which corresponds to the flame speed in the laboratory referential, is determined from saturated and non-saturated images. The burning velocity, i.e. the consumption rate of the reactants by the flame front, is then presented. With saturated images, the flame surface area is under-estimated, around 10-20 %, yielding to over-estimated burning velocity.

Maame Adwoa Bentumah Animpong, William Owusu Oduro, Joyce Koranteng et al.

We demonstrated the formulation of wood plastic composite (WPC) materials with flexural strength of 13.69 ± 0.09 MPa for applications in outdoor fencing using municipal waste precursors like low density polyethylene (LDPE) plastics (54.0 wt. %), sawn wood dust with particle size between 64 and 500 μm derived from variable hardwood species (36.0 wt. %) and used automotive engine oil (10 wt. %). The WPC panels were prepared by pre-compounding, extruding at a screw auger torque of 79.8 Nm and pressing through a rectangular mould of dimension 132 mm × 37 mm × 5 mm at temperature 150 °C. The efficacy of black waste oil, as a coupling agent, was demonstrated by the absence of voids and pull-outs on microscopic examination using scanning electron microscopy. No hazardous substances were exhaled during thermo-gravimetric mass spectrometry analysis. The percentage crystallinity of the LDPE in the as-prepared material determined by differential scanning calorimetry was 11.3%. Keywords: Wood plastic composites, Low density polyethylene, Wood dust, Physical, Thermal and mechanical properties

Efe Çetin Yilmaz, Recep Sadeler, Zeynep Yeşil Duymuş et al.

Background: The purpose of this study was to investigate two-body wear resistance and hardness of different three modern composite materials. Methods: In the conditions recommended by the manufacturer five pieces were produced from each material. All samples were kept in distill water for 1 week and determined Vickers hardness (HV) before two-body wear test. Then, two-body wear tests were performed using a computer controlled chewing simulator. In this study, the chewing simulator was programmed to provide a 2 mm vertical movement and a 0.7 mm horizontal movement. For each wear test, Al2O3 with a diameter of 6 mm was used as antagonist material. The mean volume loss of all samples after the wear tests was determined with three dimensional profilometry. In addition to a random specimen was selected from each test group and SEM images were taken for analysis of wear tracks. Mean and standard deviation values were calculated and evaluated with the one-way ANOVA. Results: The hardness values of the materials tested in this study were measured between about 49 HV and 78 HV. Significantly, lowest mean volume loss was detected for the Heliomolar at about 3.1 μm3 whereas the highest mean volume loss was detected for the Silorane at about 6.4 μm3 after 360.000 chewing cycles. Conclusions: However, among the materials tested in this study suggested correlations between HV and two-body wear resistance are not significant.

Dongying Hu, Peng Wang, Jian Li et al.

Microcrystalline cellulose (MCC) was functionalized with quaternary amine groups for use as an adsorbent to remove Congo Red dye (CR) from aqueous solution. The ultrasonic pretreatment of MCC was investigated during its functionalization. Characterization was conducted using infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The batch adsorption of the functionalized MCC was studied to evaluate the effects of dye concentration, pH of solution, temperature, and NaCl concentration on the adsorption CR. The adsorbent (FM-1) obtained using ultrasonic pretreatment of MCC under 10.8 kJ•g–1 exhibited an adsorption capacity of 304 mg•g–1 at initial pH under a dose of 0.1 g•L–1 and initial concentration of 80 mg•L–1. After functionalization, the FT-IR and XPS results indicated that the quaternary amine group was successfully grafted onto the cellulose, the surface was transformed to be coarse and porous, and the crystalline structure of the original cellulose was disrupted. FM-1 has been shown to be a promising and efficient adsorbent for the removal of CR from an aqueous solution.

Nipaporn Meepun, Suphawuth Siriket, Saravut Dejmanee

The method for reliable determination of Cd(II) by square wave adsorptive cathodic stripping voltammetry was done. The technique involves an interfacial adsorption of Cd(II) as Cd-cupferron complex on a Nafion-coated bismuth film electrode and subsequent stripping from the electrode by square wave cathodic voltammetric and the reduction of Cd-cupferron complex. The optimum conditions of direct reduction of Cd(II) ions was observed by 0.1 M acetate buffer electrolyte (pH 4.0) containing with 0.04 mM cupferron and 0.4 mg L-1 Bi(III) of an accumulation potential at -300 mV versus Ag/AgCl and accumulation time 60 seconds. Under these optimum conditions, the linear concentration and detection limit (3σ) were found in the range of 3.0 to 40.0 μg L-1 and 0.38 μg L-1, respectively. The relative standard deviation was 2.4% at the 5 μg L-1 (n=10). The procedure has been applied to the determination of Cd(II) in marine algae samples with satisfactory results.

Essam Abdul-Jalil Saeed, Hamed H.Abdulah, Ayad A. Al-Haleem

In this study, a review of variety of processes that are used in the treatment produced water prior to reuse or to responsible disposal are presented with their environmental issues and economical benefits. Samples of produced water from five locations in Rumaila oilfield/in south of Iraq were taken and analyzed for their contents of brine, some heavy metals, total suspended solids and oil and grease. Moreover, two samples of water were treated using reverse osmosis technique which showed its ability to treat such contaminated water. The results showed that the environmental impact of produced water arises from its chemical composition; i.e., its salt content, its heavy metals, and hydrocarbon contents.