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Rational design and synthesis of bifunctional oxygen electrocatalysts with high activity and stability are key challenges in the development of rechargeable Zn-air batteries (ZABs). In this paper, tungsten carbide (WC) and Co7Fe3 embedded in N,P co-doped hierarchical carbon (WC/Co7Fe3-NPHC) was prepared by using zeolite imidazolate frameworks as precursor. Density functional theory demonstrates that the mutual adjustment among the WC, Co7Fe3, and N,P co-doped carbon at the three-phase heterojunction interface makes the catalyst possess moderate adsorption strength, and greatly improves the conductivity and electron transfer rate of the catalyst. As a result, the WC/Co7Fe3-NPHC exhibits a low overall oxygen redox potential difference of 0.72 V, while the ZAB assembled by WC/Co7Fe3-NPHC as an air cathode exhibits ultra-long cycle stability of over 550 h. Futhermore, WC/Co7Fe3-NPHC can keep good charge and discharge stability at different bending angles when applied to flexible solid ZAB. [ABSTRACT FROM AUTHOR]

The discolorations or abnormal colors in meat and meat products during processing and storage have negative effects on their commercial value. In this study, myoglobin content (MetMb and OxyMb) in Tan mutton was rapidly detected using near-infrared hyperspectral imaging (NIR-HSI) system (900–1700 nm), and built predictive models with full wavebands (FW) based on partial least squares regression (PLSR), least-squares support vector machines (LSSVM), and back propagation neuron network (BP). To reduce the computational complexity of calibration models, feature bands were obtained by bootstrapping soft shrinkage (BOSS), variable combination population analysis coupled with iteratively retains informative variables (VCPA-IRIV), and competitive adaptive reweighted sampling (CARS), respectively. The optimized BP model based on feature wavebands with BOSS method selection displayed the best capability for predicting MetMb level (R2C = 0.8340, R2P = 0.8253 RMSEC = 3.1592, RMSEP = 3.2918). In addition, the simplified VCPA-IRIV-BP model was significant in predicting OxyMb content with R2C, R2P, RMSEC, and RMSEP values of 0.8024, 0.8680, 3.4676, and 2.7605, respectively. Results provided a theoretical reference for rapid evaluation of myoglobin content in other animal products via NIR-HSI. [ABSTRACT FROM AUTHOR]

The weight loss and spoilage of post-harvest fruits and vegetables (FVS) occur as a result of physiological and biological processes, the rates of which are influenced primarily by product temperature. In order to maintain the freshness of FVS and reduce losses, it is necessary to cool the product as soon as possible after harvest. Precooling is considered such an effective technique because it quickly removes field heat from FVS, thereby preventing deterioration and senescence. With the increasing demand for fresh FVS, the optimization of precooling technology has received extensive attention, especially the research on its basic principle, that is, the heat and mass transfer (HMT) between FVS and the precooling environment. Therefore, this paper reviews the advantages and disadvantages of several main precooling techniques, their HMT processes, the research methods and detection techniques of HMT, and the simulation and application based on numerical technology. Precooling techniques include room cooling, forced-air cooling, hydrocooling, and vacuum cooling. These advanced detection techniques for HMT include magnetic resonance imaging, particle image velocimetry, infrared thermography, nuclear magnetic resonance, bioelectric impedance analysis, dilatometry, thermogravimetric analysis, and X-ray CT. HMT research mainly adopts porous media method, direct numerical simulation, cell growth simulation. Their applications focus on computational fluid dynamics and the lattice Boltzmann method. Furthermore, this paper highlights the application of the computer field in FVS precooling and provides perspectives on the directions for future research. [ABSTRACT FROM AUTHOR]

A facile and economic procedure was provided to synthesize α-Fe2O3 nanofibers. In this procedure, porous α-Fe2O3 nanofibers were obtained by a single-polymer/binary-solvent system, while solid α-Fe2O3 nanofibers were prepared by a single-polymer/single-solvent system. The crystal structure and morphology of both samples were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption isotherms. The formation mechanism of porous structure was based on solvent evaporation-induced phase separation by the use of mixed solvents with different volatility. Furthermore, ethanol-sensing performance of the porous α-Fe2O3 nanofibers was evaluated and compared with solid α-Fe2O3 nanofibers. Results from gas-sensing measurements reveal that porous α-Fe2O3 nanofibers exhibit higher sensitivity and slightly longer recovery time than solid α-Fe2O3 nanofibers. Over all, the gas sensor based on porous α-Fe2O3 nanofibers shows excellent ethanol-sensing capability with high sensitivity and ultrafast response/recovery behaviors, indicating its potential application as a real-time monitoring gas sensor. [ABSTRACT FROM AUTHOR]

The rate equations and power evolution equations of erbium-doped telluride glass fiber amplifier for both 1.530 and 2.700 μm lasers are solved numerically, the dependences of gain spectra on fiber length, dopant concentration and pump power are analyzed, and the gain of 2.700 μm laser is calculated and compared with the experimental result from reference. The numerical analysis shows that with 8 × 10 ion/m erbium ion concentration, 5m fiber length and 600mW pump power, the gains at 1.530 and 2.700 μm may achieve 23dB or so. With larger power pump and higher dopant concentration, a net gain of 17 dB is obtained from the Er-doped telluride glass fiber amplifier for 110mW input signal. This fiber amplifier is promising for both 1.530 μm signal amplification and 2.700 μm laser amplification. [ABSTRACT FROM AUTHOR]

The rate equations and the power evolution equations based on excited state absorption (ESA) and cooperative upconversion (CUC) of high concentration erbium-doped yttrium aluminum garnet (YAG) transparent ceramic waveguide amplifier are set up to analyze the effects of the pump power, active ion concentration and waveguide length on the amplifier gain and noise figure (NF). The numerical analysis predicts that with a pump power of 100mW, an active ion concentration of 1.0×10 ion/m and a waveguide length of 3 cm, a small-signal gain of 30 dB and an NF of 5 dB can be achieved in the micro-chip amplifier. [ABSTRACT FROM AUTHOR]

Sm-doped SrSnO (SrSnO:Sm) nanopowders were synthesized by a simple hydrothermal method and followed by a heat treatment process. The as-synthesized nanopowders were assembled in dye-sensitized solar cells (DSSCs) to investigate their photoelectric properties. X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive spectrometer (EDS) confirmed the formation of SrSnO:Sm nanopowders with perovskite structure. The ultraviolet-visible absorption spectra and photoluminescence spectra indicate a down-conversion from ultraviolet light to visible light which matches the strong absorption region of the N719 dye. The DSSC based on SrSnO:Sm photo-anode improved its photoelectric conversion efficiency ( η) via the down-conversion of doped Sm. Under the irradiation of the simulated sunlight with 100 mW/cm, the DSSC based on SrSnO doping with Sm of 0.6 wt% showed the highest η of 1.54%, which improved 71.11% compared with the DSSC based on pure SrSnO. [ABSTRACT FROM AUTHOR]

The efficient biological treatment of saline wastewater has been limited by the low activities of microorganisms under saline conditions. High salinity poses unbalance osmotic stress across the cell wall and even leads to cell plasmolysis. In this work, we aim to isolate salt-tolerant bacterial strains from activated sludge, and apply them for degrading chemical oxygen demand (COD) of saline organic wastewater. Two salt-tolerant strains were screened and isolated from activated sludge, which was domesticated with salty water for over 300 days. The two strains were identified as Bacillus cereus (strain A) and Bacillus anthracis (strain B) through 16S rRNA sequencing. The degradation characteristics of strain A were explored. The results showed the relative membrane permeability of strain A remained stable under high salt stress, which glycine and proline play an important role to maintain cell osmotic. The protein and soluble sugar amounts of strain were increased by higher salt concentrations. In simulating saline wastewater, the optimum culture temperature, pH, salinity, influent COD concentration and inoculation amount of strain A were 35 °C, 9, 4%, 8000 mg L−1, 6%, respectively. Optimal conditions could provide guidance for the treatment of practical saline wastewater. The linear regression model of each impact factor built based on the result PB experiment revealed that cross-linking time has the most significant influence on COD removal for salt-tolerant strains. It will provide theoretical basis for biological treatment of saline organic wastewater. [ABSTRACT FROM AUTHOR]