Search

Background: Aflatoxin B1 (AFB1) is a prevalent contaminant in agricultural products, presenting significant risks to animal health. CotA laccase from Bacillus licheniformis has shown significant efficacy in degrading mycotoxins in vitro test. The efficacy of Bacillus CotA laccase in animals, however, remains to be confirmed. A 2 × 2 factorial design was used to investigate the effects of Bacillus CotA laccase level (0 or 1 U/kg), AFB1 challenge (challenged or unchallenged) and their interactions on ducks. The purpose of this study was to evaluate the efficacy of Bacillus CotA laccase in alleviating AFB1 toxicosis of ducks. Results: Bacillus CotA laccase alleviated AFB1-induced declines in growth performance of ducks accompanied by improved average daily gain (ADG) and lower feed/gain ratio (F/G). Bacillus CotA laccase ameliorated AFB1-induced gut barrier dysfunctions and inflammation testified by increasing the jejunal villi height/crypt depth ratio (VH/CD) and the mRNA expression of tight junction protein 1 (TJP1) and zonula occluden-1 (ZO-1) as well as decreasing the expression of inflammation-related genes in the jejunum of ducks. Amino acid metabolome showed that Bacillus CotA laccase ameliorated AFB1-induced amino acid metabolism disorders evidenced by increasing the level of glutamic acid in serum and upregulating the expression of amino acid transport related genes in jejunum of ducks. Bacillus CotA laccase ameliorated AFB1-induced liver injury testified by suppressing oxidative stress, inhibiting apoptosis, and downregulating the expression of hepatic metabolic enzyme related genes of ducks. Moreover, Bacillus CotA laccase degraded AFB1 in digestive tract of ducks, resulting in the reduced absorption level of AFB1 across intestinal epithelium testified by the decreased level of AFB1-DNA adduct in the liver, and the reduced content of AFB1 residues in liver and feces of ducks. Conclusions: Bacillus CotA laccase effectively improved the growth performance, intestinal health, amino acid metabolism and hepatic aflatoxin metabolism of ducks fed AFB1 diets, highlighting its potential as an efficient and safe feed enzyme for AFB1 degradation in animal production. [ABSTRACT FROM AUTHOR]

Copyright of Laboratory Animals is the property of Sage Publications, Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Since 1998, comprehensive housing marketization has led to a more complex urban residential space structure in China, as evidenced by the changes in new commercial housing. The current stage is critical for China in its pursuit of high-quality and sustainable urban development, with the spatial structure of housing being a key aspect in achieving this goal. In order to clarify the characteristics of the urban residential space in China and grasp the spatio-temporal changes of new commercial housing, this study takes the data of new commercial housing projects in Xi'an, northwest China, from 2006 to 2022 as the basis, and uses the GIS method to explore the characteristics of the spatio-temporal evolution of the urban residential space and to investigate the factors influencing it. The results reveal changes in the number, size, and spatial distribution of new commercial housing in Xi'an. The evolution of residential space is influenced by cultural and social changes, population, and economic factors, in addition to the main influence of national policies. The renewal of urban villages into commercial housing projects is a prominent feature of changes in urban residential space, which saves construction land and improves residents' living conditions. Finally, the expansion of urban residential space parallels the urbanization process, showing a pattern of 'external expansion accompanied by internal renewal', and the evolution process and property rights management are different from those of other countries. [ABSTRACT FROM AUTHOR]

We present a new algorithm Directional Optimization Search with Surrogate (DOSS), for optimizing problems with box constraints and a computationally expensive black-box objective function. DOSS is a radial basis function (RBF) based method that mainly focuses on higher dimensional and computationally expensive objective functions that can be multimodal. DOSS introduces three new techniques not previously used in earlier RBF algorithms, including using a combination of the coordinates knowledge level, fewer initial sampling points, and the surrogate's gradient information. Numerical results on a test set including 14 test problems with 36, 48, and 60 dimensions show that DOSS outperforms two recently published algorithms RBFOpt and TuRBO, and earlier RBF algorithms such as DYCORS. TuRBO is a Gaussian process based optimization algorithm, which outperformed earlier state-of-the-art methods. DOSS algorithm also has a good performance on real-world optimization problems, including robot pushing and rover trajectory planning problems. Almost sure convergence for the DOSS algorithm is also proven in this paper. An implementation of DOSS is available at https://doi.org/10.5281/zenodo.13731558. [ABSTRACT FROM AUTHOR]

Aflatoxin B1 (AFB1) contamination is a serious threat to nutritional safety and public health. The CotA-laccase from Bacillus licheniformis ANSB821 previously reported by our laboratory showed great potential to degrade AFB1 without redox mediators. However, the use of this CotA-laccase to remove AFB1 in animal feed is limited because of its low catalytic efficiency and low expression level. In order to make better use of this excellent enzyme to effectively degrade AFB1, twelve mutants of CotA-laccase were constructed by site-directed mutagenesis. Among these mutants, E186A and E186R showed the best degradation ability of AFB1, with degradation ratios of 82.2% and 91.8% within 12 h, which were 1.6- and 1.8-times higher than those of the wild-type CotA-laccase, respectively. The catalytic efficiencies (kcat/Km) of E186A and E186R were found to be 1.8- and 3.2-times higher, respectively, than those of the wild-type CotA-laccase. Then the expression vectors pPICZαA-N-E186A and pPICZαA-N-E186R with an optimized signal peptide were constructed and transformed into Pichia pastoris GS115. The optimized signal peptide improved the secretory expressions of E186A and E186R in P. pastoris GS115. Collectively, the current study provided ideal candidate CotA-laccase mutants for AFB1 detoxification in food and animal feed and a feasible protocol, which was desperately needed for the industrial production of CotA-laccases. [ABSTRACT FROM AUTHOR]

A new route based on HfO2 + B4C + C → HfB2 + HfC + CO reaction was developed to synthesize HfB2‐HfC hybrid powders. X‐ray diffraction, scanning electron microscopy, energy dispersive spectrometry, and transmission electron microscopy were used to evaluate the powder products. The effects of excess additions of B4C and C on the phase constituents of the powder products were investigated. Thermodynamics of relevant reactions for the synthesis of the hybrid powders were calculated to guide the selection of compositions and processing parameters. The results indicated that HfB2‐HfC hybrid powders were obtained by reaction at 1750°C for 1 h. HfB2:HfC phase content ratios showed a dependence on B4C and C additions. The obtained hybrid powders exhibited good oxidation resistance with an oxidation activation energy of 303 kJ/mol. Good sinterability of the powder products was demonstrated by spark plasma sintering at 2100°C. The consolidated ceramics based on them measured good Vickers' hardness values (>26.0 ±.5 GPa) and fracture toughness (>3.78 ±.27 MPa·m1/2). [ABSTRACT FROM AUTHOR]

Zr metal bulks were isothermally reacted with B powder at 800-1630 °C for 2-16 h to form ZrB2 layers on the Zr bulk surfaces. Diffusion kinetics of B element in association with Zr + B solid state reaction was investigated by means of XRD, SEM and EDS. Nano-sized ZrB2 grains without formation of a discernible layer were detected on the Zr surface after reaction at 800 °C for 2 h. When the reaction temperature was increased, continuous layers consisting of faceted ZrB2 grains were formed at temperatures ranging from 1200 to 1500 °C. The thickness of the ZrB2 product layers showed a parabolic dependence on time t and an exponential dependence on temperature T via − 1/RT. The Zr + B reaction calculated a diffusion activation energy G = 152.0 ± 62.4 kJ/mol for B diffusion in ZrB2. The diffusion coefficient of B element was experimentally determined to be D = 1743.4 × 10 - 12 exp - 152027.6 / R T . [ABSTRACT FROM AUTHOR]

Obtaining a uniform interface temperature field plays a crucial role in the interface bonding quality of bimetal compound rolls. Therefore, this study proposes an improved electroslag remelting cladding (ESRC) process using an external magnetic field to improve the uniformity of the interface temperature of compound rolls. The improved ESRC comprises a conventional ESRC circuit and an external coil circuit. A comprehensive 3D model, including multi-physics fields, is proposed to study the effect of external magnetic fields on the multi-physics fields and interface temperature uniformity. The simulated results demonstrate that the non-uniform Joule heat and flow fields cause a nonuniform interface temperature in the conventional ESRC. As for the improved ESRC, the magnetic flux density (Bcoil) along the z-axis is produced by an anticlockwise current of the external coil. The rotating Lorentz force is generated from the interaction between the radial current and axial Bcoil. Therefore, the slag pool flows clockwise, which enhances circumferential effective thermal conductivity. As a result, the uniformity of the temperature field and interface temperature improve. In addition, the magnetic flux density and rotational speed of the simulated results are in good agreement with those of the experimental results, which verifies the accuracy of the improved ESRC model. Therefore, an improved ESRC is efficient for industrial production of the compound roll with a uniform interface bonding quality. [ABSTRACT FROM AUTHOR]

Generating oxygen vacancies is an effective way to improve the lithium-ion storage performance of V2O5. However, the mechanism has not been theoretically investigated. In this study, first-principle calculations were performed to study the effect of oxygen vacancy on electrochemical properties of γ-V2O5 as cathode material for lithium-ion batteries. γ-V2O5 with oxygen vacancy mole fraction of 1.67% shows an open circuit voltage about 0.1 V lower than that of the perfect γ-V2O5. Oxygen vacancies generates gap states, which is beneficial to the electronic conductivity of γ-V2O5 and γ-LiV2O5. In addition, the activation energies for lithium-ion diffusion along [010] in both γ-V2O5 and γ-LiV2O5 are increased by oxygen vacancy, which might lead to the decrease of diffusion coefficient. Our results will provide guidance for further improving the lithium-ion storage performance of γ-V2O5. [ABSTRACT FROM AUTHOR]

The electrochemical properties of VPO4O as a cathode for Mg batteries were studied by performing first principles calculations. Mg insertion features a plateau at about 2.8 V up to Mg0.5VPO4O and then another plateau at around 2.2 V up to MgVPO4O, with a theoretical capacity of about 154 mA h g−1 and 144 mA h g−1, respectively. MgVPO4O is found to be dynamically stable with the absence of negative frequencies in the phonon density of states. The insertion of one Mg reduced two VO6 units instead of reducing only one VO6 unit. In addition, MgVPO4O shows an energy barrier of about 0.58 eV for Mg-ion vacancy migration along the [111] direction, which is comparable to that of many other cathode materials. Our results indicated that MgVPO4O has the potential to be a promising candidate as a cathode material for Mg batteries. [ABSTRACT FROM AUTHOR]

Abstract: Zirconium diboride (ZrB2) ceramics were prepared by reactive hot pressing of ZrB+B powder mixture. Formation of a transient liquid due to eutectic reaction of ZrB2+Zr→Leu(ZrB2+Zr) at 1661°C following peritectic decomposition of 2ZrB=ZrB2+Zr at 1250°C during heating up of the ZrB+B mixture facilitated densification. The liquid phase was subsequently eliminated via reaction of B with Zr in the eutectic liquid Leu(ZrB2+Zr) to result in a dense ZrB2 ceramic. Full density was reached after reactive hot pressing at 1900°C under 30 MPa for 1 h. The ZrB2 ceramic had a refined microstructure consisting of grains of <1.5 μm in size and relatively good Vickers hardness (21 ± 2 GPa) and flexural strength (595 ± 63 MPa). [ABSTRACT FROM AUTHOR]

A fully dense TaC ceramic was prepared by hot pressing using 10 mol% ZrC plus 5 mol% Cu as a sintering aid. Formation of (Ta, Zr)C solid solution (ss) by reaction between TaC and ZrC facilitated densification. Addition of Cu refined the microstructure and consequently improved flexural strength of the TaC ceramics. TEM investigation found ubiquitous precipitation of nanocrystallites at multigrain conjunctions. The nanocrystallites were (Ta, Zr)C solid solution with uniform dispersion in an oxygen-rich glassy matrix. Although formation of nanoprecipitates may not much affect the mechanical properties of the TaC ceramic, the structure suggested a new type of nanoceramic worth further research. [ABSTRACT FROM AUTHOR]

Metallic Si as sintering aid was effective in densifying tantalum carbide ceramic (TaC) by spark plasma sintering ( SPS) at 1700°C. Full density was reached at 5.0 mol% Si addition (equivalent to 1.088% Si in weight) and above. Enhanced densification of TaC ceramic with Si was associated with decrease in oxygen content from ~0.24 wt% in TaC powder to ~0.03 wt% in consolidated specimen. Rest of the oxygen species was collected at multigrain conjunctions to form SiO2-based liquid at high temperatures. Upon cooling, Ta, Si, O, and C dissolving in the liquid precipitated minor phases of TaSi x and SiC of low concentrations. Microstructure of TaC ceramics was refined by the Si addition, with average grain size decreasing from 11±8 μm at 1.0 mol% Si to 3±2 μm at 7.5 mol% Si addition. Ta solute in SiC and Si solute in TaC were evidenced. TaC ceramic containing 7.5 mol% Si had a relatively good flexural strength and fracture toughness of 646±51 MPa and 5.0 MPa·m1/2, respectively. [ABSTRACT FROM AUTHOR]

Present work determined the phase relations of the SiC-AlO-NdO, SiC-NdO-SiO and SiC-AlO-NdO-SiO subsystems in the Si-Al-Nd-O-C system by XRD phase analysis of samples which were prepared via the solid-state reaction using SiC, AlO, NdO and SiO as the starting materials. The phase diagrams of the subsystems were presented. SiC was compatible with each of the two Nd-aluminates of NdAlO and NdAlO in the system. NdAlO was stable at temperatures >1720 °C and compatible with SiC. Six four-phase coexistent regions were established in the quaternary SiC-AlO-NdO-SiO system at 1250 °C. Possible effects of the SiO on sintering of the SiC ceramics were discussed. [ABSTRACT FROM AUTHOR]

Phase formation sequence of the yttrium aluminates in the YO-AlO-SiC ternary system as temperature increases were investigated via x-ray diffraction (XRD). Results showed that YAM (monoclinic), YAP (perovskite) and YAG (garnet) were the yttrium aluminates presented in the solid-state reacted samples at a fixed AlO:SiC ratio of 1:1. Formation of the yttrium aluminates depended on the temperature. The YAM, YAP and YAG started to form below 1150 °C, at 1300 °C, and at 1450 °C, respectively. Accordingly, two behavior phase diagrams of the YO-AlO-SiC ternary system were recognized, one is in the temperature range of 1150-1300 °C and the other is in 1300-1450 °C, respectively. Thereafter, the phase equilibrium was reached in the temperature range of 1450-1700 °C. Effects of SiC on the phase formation processes in the ternary system were discussed. [ABSTRACT FROM AUTHOR]

Effect of electric current on sintering behavior and microstructure evolution of zirconium diboride (ZrB2) was investigated using three different configurations of Field Assisted Sintering Technology/Spark Plasma Sintering. The current flow through the ZrB2 compact was controlled by modifying the interface between the graphite punches and the electrical conductive powder. Boron nitride discs, graphite foils or direct contact with the graphite punches were the three different interfaces used in order to deflect, conduct or promote, respectively, the current during the sintering process of the electrically conductive ZrB2 ceramics. The current flow during the sintering process triggered the elimination/reduction in B2O3, leading to faster diffusion rates at high temperatures and limiting the formation of B4C secondary phase. This allows to control the final density, grain size (from 19.6 to 43.2 μm) and secondary phase formation (from 5.95 to 11.61 vol%) as well as the electrical resistivity (from 7.7 to 9.4 μΩ·cm) of the specimens. [ABSTRACT FROM AUTHOR]

High compacted aluminum nitride (AlN) substrates were prepared by aqueous tape casting. Aluminium dihydrogen phosphate was used to modify AlN particle surface from hydrolysis during casting process. The absolute value of zeta potential for the AlN particle treated by Al(H2PO4)2was 60mv at pH = 9. The slurry suitable for tape casting was prepared which possessed shear-thinning behavior and appropriate viscosity. The results showed that the green tapes own excellent properties including high bulk density, uniform pore distribution and low porosity. The samples were fired at 1700°C (lower than melting point of Pt) with pressureless sintering process which can be used to fabricate complex device. [ABSTRACT FROM PUBLISHER]

6 H- SiC powder mixed with Si3N4, Al2O3, Y2O3, and AlN was sintered in a spark plasma sintering ( SPS) equipment. The 6 H→3 C SiC transformation was concerned. Research results indicated the polytype transformation completed in less than 30 s by imposing a 14 458 W (6.2 V, 2332 A) transitory DC current at 1700°C upon cooling down from 2000°C. The fast transformation kinetic and the significant 3 C- SiC grain growth accompanying the phase transformation were suspected to be correlated with the pulsed SPS direct current. [ABSTRACT FROM AUTHOR]

The TaC0.7 composition was spark plasma sintered (SPS) at 1600°-1900°C using TaC and Ta as the starting powders. Densification process, phase evolution, microstructure development, and the mechanical properties of the composites were investigated. The results indicated that the TaC0.7 composition could be SPS to >95% of theoretical density in 5 min at 1600°C or above. The phase formation was associated with carbon diffusion from the starting particles TaC to Ta to form Ta2C and Ta6C5 as intermediate phases, and subsequently the equilibrium phases of TaC y and ζ-Ta4C3− x. The presence of lamellar ζ-Ta4C3− x regions enhanced the flexure strength (up to 972 MPa) and fracture toughness (up to 13.8 MPa·m1/2). [ABSTRACT FROM AUTHOR]

Porous α-SiAlON ceramics were fabricated using the camphene-based unidirectional freeze casting method, in which a gradient porous structure was formed as a result of the decreased solidification velocity in the freezing direction. Microstructure, porosity and pore size distribution of different parts of as-prepared samples were examined and compared, and correlated with their mechanical properties. For a given solid loading, the overall pore size and porosity of the top part were greater than those of the bottom part. Interestingly, despite its higher porosity, the flexural strength and fracture toughness of the top part were both higher than those of the bottom part, suggesting that apart from porosity, pore morphology and size affected mechanical properties of as-prepared porous α-SiAlON ceramics. [ABSTRACT FROM AUTHOR]

A correction to the article "to: Phase Relations in the Si-Al-Nd-O-C System" that was published in the 2016 issue is presented.