Changes in physicochemical properties and myofibrillar protein properties in grass carp salted by brining and injection

The aim of this study was to investigate the changes in physicochemical properties and myofibrillar protein properties of grass carp meat during brining and brine injection at 4 °C. The time reached equilibrium was 7 h in brining group and 5 h by injection, where the salt content was about 1.76%. The water content, water holding capacity and yield in injection group (86.59%, 9.18% and 110%, respectively) were higher than brining group (84.76%, 11.47%, and 108%, respectively) at equilibrium point significantly (P < 0.05). This was attributed to the more swollen filament lattices and disordered protein structure in injection group (P < 0.05). The myofibrillar protein structure was compared, including sulphydryl content, surface hydrophobicity, solubility, sodium dodecyl sulphate polyacrylamide gel electrophoresis pattern and secondary structure. The injection group presented the better quality of salted fish meat in shorter time.     

On the dependence of interfacial resistance on contact materials between cathode and interconnect in solid oxide fuel cells

The dependence of interfacial contact resistance (ICR) on contact materials between cathode and interconnect is systematically studied under both isothermal oxidation and thermal cycling conditions. Three kinds of cathode current-collecting layer (CCCL) are used, (La,Sr) (Co,Fe)O₃ (LSCF), LSCF+10%Ag, and Ag, and tested in a SUS430/CCCL/SUS430 sandwich structure to simulate the actual operation of the solid oxide fuel cells (SOFCs). Experimental results show that the ICR of LSCF+10%Ag exhibits the smallest value, in comparison with the specimens with LSCF and Ag paste, as well as the sample without a CCCL. For LSCF+10%Ag contact, the ICR increases from 0.0069 mΩ cm² to 3.74 mΩ cm² under an isothermal condition for 150 h, then increases from 3.74 mΩ cm² to 10.79 mΩ cm² after 15 thermal cycles. This work provides information for the understanding of possible mechanisms of performance degradation of SOFCs.     

Top-down preparation of Ni–Pd–P@graphitic carbon core-shell nanostructure as a non-Pt catalyst for enhanced electrocatalytic reactions

Electrochemical reactions such as the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and methanol oxidation reaction (MOR) are essential for energy conversion applications such as water electrolysis and fuel cells. Furthermore, Pt or Ir-related materials have been extensively utilized as electrocatalysts for the OER, ORR, and MOR. To reduce the utilization of precious metals, innovative catalyst structures should be proposed. Herein, we report a bi-metallic phosphide (Ni₂P and PdP₂) structure surrounded by graphitic carbon (Ni–Pd–P/C) with an enhanced electrochemical activity as compared to conventional electrocatalysts. Despite the low Pd content of 3 at%, Ni–Pd–P/C exhibits a low overpotential of 330 mV at 10 mA cm^?2 in the OER, high specific activity (2.82 mA cm^?2 at 0.8 V) for the ORR, and a high current density of 1.101 A mg^?1 for the MOR. The superior electrochemical performance of Ni–Pd–P/C may be attributed to the synergistic effect of the bi-metallic phosphide structure and core-shell structure formed by graphitic carbon.     

Advances in statistical mechanics of rock masses and its engineering applications

To efficiently link the continuum mechanics for rocks with the structural statistics of rock masses,a theoretical and methodological system called the statistical mechanics of rock masses(SMRM)was developed in the past three decades.In SMRM,equivalent continuum models of stressestrain relationship,strength and failure probability for jointed rock masses were established,which were based on the geometric probability models characterising the rock mass structure.This follows the statistical physics,the continuum mechanics,the fracture mechanics and the weakest link hypothesis.A general constitutive model and complete stressestrain models under compressive and shear conditions were also developed as the derivatives of the SMRM theory.An SMRM calculation system was then developed to provide fast and precise solutions for parameter estimations of rock masses,such as full-direction rock quality designation(RQD),elastic modulus,Coulomb compressive strength,rock mass quality rating,and Poisson’s ratio and shear strength.The constitutive equations involved in SMRM were integrated into a FLAC3D based numerical module to apply for engineering rock masses.It is also capable of analysing the complete deformation of rock masses and active reinforcement of engineering rock masses.Examples of engineering applications of SMRM were presented,including a rock mass at QBT hydropower station in northwestern China,a dam slope of Zongo II hydropower station in D.R.Congo,an open-pit mine in Dexing,China,an underground powerhouse of Jinping I hydropower station in southwestern China,and a typical circular tunnel in Lanzhou-Chongqing railway,China.These applications verified the reliability of the SMRM and demonstrated its applicability to broad engineering issues associated with jointed rock masses.     

Influence of soil density on gas permeability and water retention in soils amended with in-house produced biochar

Biochar has been used as an environment-friendly enhancer to improve the hydraulic properties(e.g.suction and water retention) of soil.However,variations in densities alter the properties of the soil-biochar mix.Such density variations are observed in agriculture(loosely compacted) and engineering(densely compacted) applications.The influence of biochar amendment on gas permeability of soil has been barely investigated,especially for soil with diffe rent densities.The maj or obj ective of this study is to investigate the water retention capacity,and gas permeability of biochar-amended soil(BAS) with different biochar contents under varying degree of compaction(DOC) conditions.In-house produced novel biochar was mixed with the soil at different amendment rates(i.e.biochar contents of 0%,5% and 10%).All BAS samples were compacted at three DOCs(65%,80% and 95%) in polyvinyl chloride(PVC)tubes.Each soil column was subjected to drying-wetting cycles,during which soil suction,water content,and gas permeability were measured.A simplified theoretical framework for estimating the void ratio of BAS was proposed.The experimental results reveal that the addition of biochar significantly decreased gas permeability k_g as compared with that of bare soil(BS).However,the addition of 5%biochar is found to be optimum in decreasing kg with an increase of DOC(i.e.k_(g,65%) k_(g,80%) k_(g,95%)) at a relatively low suction range(200 kPa) because both biochar and compaction treatment reduce the connected pores.     

Novel cobalt-free Pr2Ni1-xNbxO4 (x = 0, 0.05, 0.10, and 0.15) perovskite as the cathode material for IT-SOFC

The cobalt-free cathode materials with high activity is critical to the commercial application of medium temperature solid oxide fuel cells (IT-SOFC). Herein, a series of cobalt-free Nb-doped Pr₂Ni_1-xNb_xO₄ (x = 0, 0.05, 0.10, and 0.15) perovskite oxides were successfully prepared, and the effects of Nb-doping on the structure, thermal stability and electrochemical properties of the cathode material are studied in detail. The Pr₂Ni_1-xNb_xO₄ exhibits a K₂NiF₄ type structure with Fmmm space group. The Nb⁵⁺ cations that doped into Pr₂NiO₄ replaces the Ni site, which increases the surface oxygen content, then effectively eliminates the phase transition of Pr₂NiO₄ and significantly improves the ORR catalytic activity. The Pr₂Ni_0.9Nb_0.1O₄ was found to occupy the lowest polarization resistance of 0.057 Ω cm², and the peak power density of single cells supported by the electrolyte is 0.576 W cm^?2 at 700 °C, which has good long-term stability.     

A Two-Stage Genetic Algorithm for Molding Parameters Optimization for Minimized Residual Stresses in Composite Laminates During Curing

The residual stress generated during the curing process of composite structures will seriously reduce the material performance. This paper presents a two-stage genetic algorithm (GA) procedure to inversely determine the optimal molding parameters that minimize residual stresses. In our proposed two-stage GA procedure, a finite element model for Multiphysics simulation is first created to compute the residual stresses of the composite laminated plate for a given temperature curve. The FEM model is then modulated by an improved GA with the residual stresses of the plate as the objective function. The improved GA is called in two-stages: the first stage determines a set of likelihoods of the modeling parameters around which the "optimal" parameters may reside. The 2^nd stage zooms-in the areas centered by these likelihoods, which finds molding parameters that minimize the residual stresses. The results show that the proposed two-stage genetic algorithm is more efficient than the traditional genetic algorithm.

     

TiO2-rutile/anatase homojunction with enhanced charge separation for photoelectrochemical water splitting

The mismatched interfaces of heterojunction usually have lots of defects, deriving in recombination of generated electron-hole pairs. On the other hand, homojunction interfaces are considered to be beneficial to the separation of charge carriers due to the similar characteristics in two sides of homojunction. TiO₂ have rutile and anatase two typical photoactive phases in nature. In this work, TiO₂-rutile/anatase (TiO₂-R/A) homojunction photoanode is fabricated by in situ growth of anatase TiO₂ on TiO₂-R surface. By contrast with TiO₂-rutile/rutile (TiO₂-R/R) photoanode, TiO₂-R/A displays higher photocurrent density (1.70 mA cm^?2 at 0.6 V vs. SCE). Deep insight into the mechanism suggests that TiO₂-R/A homojunction has intense band bending and enhanced surface area, which facilitate the charge separation and transmission. This study offers some novel insights to design and fabricate semiconductors photoanodes for highly efficient photocatalytic reactions.     

Modeling and numerical investigation of hydrogen nucleate flow boiling heat transfer

Liquid hydrogen flow boiling heat transfer in tubes is of great importance in the hydrogen applications such as superconductor cooling, hydrogen fueling. In the present study, a numerical model for hydrogen nucleate flow boiling based on the wall partition heat flux model is established. The key parameters in the model such as active nucleation site density, bubble departure diameter and frequency are carefully discussed and determined to facilitate the modeling and simulation of hydrogen flow boiling. Simulation results of the numerical model show reasonably well agreement with experimental data from different research groups in a wide operation condition range with the means absolute error (MAE) of 10.6% for saturated and 5.3% for subcooled flow boiling. Based on the model, wall heat flux components and void fraction distribution of hydrogen flow boiling are studied. Effects of mass flow rate and wall heat flux on the flow boiling heat transfer performance are investigated. It is found that in the hydrogen nucleate flow boiling, the predominated factor is the Boiling number, rather than the vapor quality. A new simple correlation is proposed for predicting hydrogen saturated nucleate flow boiling Nusselt number. The MAE between the correlation predicted and experimentally measured Nusselt number is 13.6% for circular tubes and 12.5% for rectangular tubes. The new correlation is applicable in the range of channel diameter 4–6.35 mm, Reynolds number 64000–660,000, saturation temperature 22–29 K, Boiling number 8.37 × 10^?5–2.33 × 10^?3.