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Ionic thermoregulated osmotic energy conversion in nanochannels synergistically utilizes osmotic and thermal energy for power generation based on ionic selective transport in charged nano-membranes under salinity gradients and thermal regulations. Currently, no explicit general dimensionless formulas exist that reflect the relationship between impact factors and performance to guide performance designs. In this study, data-driven insight is presented to establish a framework for obtaining explicit and general relational expressions based on data augmentation using the similarity principle and deep learning. The original database is derived from a finite element simulation with 10,000 dimensional samples, then augmented to 30,000 dimensional samples via similarity principle-based data augmentation. Subsequently, a deep neural network model with decay algorithms is employed to expand the database to new 300,000 dimensional samples with a prediction accuracy exceeding 98 %, which are further converted to dimensionless forms for multiple linear regression. Three dimensionless and explicit formulas for the electrical potential, output power, and energy conversion efficiency are obtained, which indicate determination coefficients of 0.91, 0.93, and 0.92, respectively. Furthermore, considering actual experimental and application situations, the modified dimensionless formula of the output power predicts the experimental results with an average error of 7.80 %. This study efficiently alleviates experimental burden and facilitates engineering applications. [Display omitted] • Data-driven insight is presented to establish a framework for general formulas. • Primary data augmentation is achieved by similarity principle. • Secondary data augmentation is realized by deep learning. • Explicit dimensionless formulas with high determination coefficients are obtained. [ABSTRACT FROM AUTHOR]

The immiscible bimetallic composites play an important role in civilian industries and aerospace fields owing to their integrated mechanical and physical properties. However, metallic composites of immiscible constituents suffer from one critical drawback of weak interface bonding, which makes the composites particularly vulnerable at elevated service temperatures. Here we proposed a novel strategy to resolve the challenge by creating low-energy phase interfaces in a typical immiscible bimetallic W–Cu composite. This was achieved by in-situ reactions of WO 3 and CuO with WC, which acts in a dual function as the reducing agent for the reactions and an interface forming agent. The sintered W-WC-Cu composite possessed a significant number of low-energy WC/W and WC/Cu interfaces and exhibited a compressive strength of 609 MPa and a compressive ductility of 22.6 % at 600 °C, which ranks among the highest in similar composites. The characteristics of WC/W and WC/Cu interfaces and their effects on the mechanical behavior of the composite were demonstrated by the timely and atomic-resolved high-temperature mechanical investigations. The introduced stable interfaces were also found to induce [ 1 ‾ 11] BCC → [011] FCC phase transformation of W as another mechanism of plastic deformation in addition to dislocation activities in W and Cu. This study provides a new approach to greatly enhance the mechanical properties of the immiscible metallic composites. [Display omitted] • Constructing low-energy and stable interfaces strategy for immiscible bimetal composites. • Superior strength-ductility synergy for the interfacial design of W-WC-Cu composite. • Inserted specific interfaces can induce an allotropic transformation as an additional plastic deformation mechanism. [ABSTRACT FROM AUTHOR]

• An integrated heat sink with ionic wind for heat dissipation of high-power LEDs is developed. • The multi-physical characteristics of discharge, flow, and heat transfer are studied. • The impact degrees of structural parameters are analyzed. • Optimization of parameters and performance is realized and verified. Light-emitting diodes (LEDs) are becoming increasingly high-power and compact, which makes rotary fans incompetent in some cooling situations. The ionic wind technique can compensate for the shortcomings of rotating fans, owing to its benefits of no moving parts and compact structure. Integrating the ionic wind generator with heat dissipation fins can effectively reduce the size of LED devices, but research in this area is still insufficient. In this study, an integrated ionic wind heat sink is designed for cooling LEDs. The multi-physical characteristics of discharge, flow, and heat transfer are numerically studied. The geometric parameters' impact degree and mechanism on the multi-physical characteristics are analyzed. The performance optimization of the integrated heat sink is realized and verified. The fin length, flow channel center angle, and relative position of the fin have a large influence on the average velocity of ionic wind. The relative position of the wire electrode determines the electric field strength distribution, and it has the greatest influence on the ionic wind performance. The emitting electrode being placed at the inlet edge of the collecting electrode produces a high ionic wind flow rate. The integrated ionic wind heat sink designed in this study exhibits an outstanding cooling performance and temperature uniformity. This device can cool down the surface of a heat source with a power of 200 W to below 91 °C and make the average heat transfer coefficient reach 18.6 W/(m2·K). This study proposes a valuable method to optimize the integrated ionic wind heat sink for cooling high-power electronic devices. [ABSTRACT FROM AUTHOR]

WAAM-LDM hybrid additive manufacturing can achieve high efficiency and high precision preparation of Ti-6Al-4V alloy. However, the inhomogeneous microstructure of WAAM-LDMed Ti-6Al-4V samples results in overall poor tensile properties. Therefore, this paper attempts to ameliorate the inhomogeneous microstructure of the hybrid sample by STA, and simultaneously improve the strength and plasticity. The results showed that the WAAM zone and HAZ were composed of α colonies, the RZ and LDM zone were distributed with fine basketweave structure of the AD samples. With the introduction of STA, the microstructure of each zone of the hybrid sample changes and transformed into a 'dual-phase' structure with bi-modal α p and β t. With the increase of aging temperature, the volume fraction of β t increased and the volume fraction of α p phase decreased, accompanied by the formation of bulk α phase and the coarsening of α s phase. It is worth noting that the strength of WAAM zone was obviously improved by STA, and the fracture positions of the STA samples were randomly distributed in the WAAM and LDM zones. Additionally, with the aging temperature increased, the strength of WAAM-LDMed samples was weakened, and the ductility was improved because the coarsened bulk α played a role of coordinating deformation in the tensile process. The excellent strength and ductility (UTS = 976 MPa, YS = 876 MPa, EL = 13.57%) of WAAM-LDMed samples was achieved at aging temperature 750 °C, compared with the AD samples (UTS = 860 MPa, YS = 767 MPa, EL = 12.5%). Finally, by optimizing the STA (940 °C/1 h/WQ + 750 °C/4 h/AC), the amelioration of the microstructure and the improvement of the strength-ductility of the hybrid samples were achieved. • The microstructure of WAAM-LDM sample is homogenized into α p + β t by STA. • STA treatment makes the strength of WAAM zone comparable to that of LDM zone. • The WAAM-LDM sample prepared by STA obtain excellent strength and ductility. [ABSTRACT FROM AUTHOR]

Trichomonas gallinae is a protozoa that parasitizes the upper gastrointestinal and respiratory tracts of various animals and birds, including Columbidae, Passeriformes, and Falconiformes. Polymerase chain reaction-based T. gallinae ITS1/5.8S/ITS2 gene typing yields inconsistent results owing to methodological differences. To standardize the statistical analysis of T. gallinae genotype distributions, this study employed MEGA-X software with the Tamamura 3-parameter (T92) + G model in the neighbor-joining method, with 2,000 bootstrap replicates, to calculate a systematic evolutionary tree. The resulting tree comprised 12 branches, ITS-OBT-Tg-1 to ITS-OBT-Tgl, with similar phylogenetic relationships. Relevant literature review yielded T. gallinae prevalence data in Columbidae. Statistical analysis was conducted from two perspectives: non-biological and biological factors, using chi-square tests and ordered logistic regression analysis. T. gallinae positivity rates differed significantly across diverse regions (χ2 = 4,609.9, P = 0.000, df = 4) and at various times (χ2 = 2,810.8, P = 0.000, df = 3). However, temperature and precipitation did not significantly affect T. gallinae positivity rates. Additionally, T. gallinae positivity rates differed significantly among diverse hosts (χ2 = 2,958.6, P = 0.000, df = 14) and by host age (χ2 = 478.5, P = 0.000, df = 2) and sex (χ2 = 96.00, P = 0.000, df = 1). This comprehensive analysis aimed to control T. gallinae transmission, reduce economic and species resource losses, and provide a foundation for future related research. [Display omitted] • Constructed a systematic evolutionary tree with 12 branches representing different genotypes of T. gallinae. • Significant differences in T. gallinae positivity rates observed across diverse regions and time periods. • T. gallinae positivity rates varied significantly among different hosts, host ages, and sexes. [ABSTRACT FROM AUTHOR]

Abstract An ionic wind pump is an energy-saving device that can produce a volume flow when electrodes are applied with high voltage. Compared to the traditional methods, ionic wind pumps possess the advantages of low energy consumption, no moving parts, compact structure and flexible design. In this study, a large-size ionic wind pump, consisting of many single regular hexagonal needle-ring ionic wind generators, was developed as the preliminary model. However, its experimental performance was not as good as our expectations. In order to improve this preliminary model, a simulation method was used to investigate the configuration factors of the single ionic wind pump. In the optimized model, mesh gap is 6 mm, eccentricity is 0.26, section area is 238.44 mm2 and needle electrode number is 3. In subsequent experiments, the final optimized large-size ionic wind pump showed a great promotion in velocity, and the maximum average velocity of the optimized pump was higher than the preliminary model by 13.3%. Our numerical simulation and experiment results have practical significance in designing ionic wind pumps. Highlights • A 3D numerical model is established for large size ionic wind pump. • Influences of multi-parameter on the performance of ionic wind pump are investigated by numerical and experimental method. • Optimized large-size ionic wind pump showed a great promotion in velocity. [ABSTRACT FROM AUTHOR]

Osmotic energy conversion is a promising method of sustainable electricity generation using seawater and river water. Artificial pure NaCl solutions are commonly used, whereas the effects of multivalent-ion ingredients present in natural seawater on osmotic power generation remain unclear. In this study, the impacts of coexisting ions in multicomponent seawater (MS) are experimentally assessed using graphene oxide membrane (GOM). Divalent cation in MS shows inferior transport to monovalent cation, thereby presenting a lower power density than when using pure NaCl solutions. Inspired by experimental results, an interfacial binding rope theory is proposed to clarify ion-wall interactions and cation transport in sub-nanochannels with hydrophilic functional groups. The binding rope networks include direct cation-wall connections mediated by composition-changed hydration shells, indirect connections by H-bonds linking solvated water molecules and functional groups, and electrostatic attractions between cations and negatively charged surfaces. The theory feasibility is confirmed by first-principles calculations focusing on the charge distribution, binding site and length, surface electrification, and cation diffusivity and selectivity in GOM sub-nanochannels. Divalent cation diffuses slower than monovalent cation in both pure solutions and confined channels. For the mixed solution in channels, both monovalent and divalent cations show worse diffusivities due to additional monovalent-divalent electrostatic repulsions, as well as inferior cation selectivity due to weakened deprotonation reactions. Bridged by environment-controlled interfacial potential distribution, ion diffusivity, and ion selectivity, this theory guides the improvement of MS-based osmotic performance under regulations of concentration gradient, pH, and temperature. A power density of 8.52 W m–2 and stable output within 27 days are achieved. The interfacial binding rope theory could be popularized to refine the transport mechanisms of various cations in diverse hydrophilic sub-nanochannel materials, promoting the application of osmotic power generation and other nanoscale technologies. [Display omitted] • Multicomponent seawater shows lower osmotic power density than pure NaCl solution. • Interfacial binding rope theory for ion transport in sub-nanochannels is inspired. • This theory is verified by first-principles calculations. • The theory guides the improvement of osmotic power density. [ABSTRACT FROM AUTHOR]

In this paper, a 3-D model of an electrostatic fluid accelerator was simulated using the finite element method (as implemented in COMSOL Multiphysics). To investigate the heat transfer performance of the accelerator, the impinging flow of the accelerator was used to cool down a heating round plate. The heat transfer coefficient and temperature distribution of the plate were numerically investigated with respect to the heat flux and radius of the round plate, and a comparison was made between the impinging flow of the accelerator and a uniform jet flow. To explore this in greater depth, a non-uniform heat flux was applied on the round plate to study the cooling effect of the accelerator on the surface with a hot spot. The effects of the hot spot heat flux and the hot spot size were then investigated. This study provides a reference for the practical cooling process of commercial chips, with and without hot spots, by adopting electrostatic fluid accelerators. [ABSTRACT FROM AUTHOR]

Abstract: According to different image completion purposes, we divide it into two different kinds of circumstances. For different situations, we use different fusion technology to achieve image completion, then we present a new framework for image completion based on image fusion technologies. [Copyright &y& Elsevier]

• Multiple needles-to-ring ionic wind devices are designed for cooling electronic components. • A full 3D multi-physical numerical method is proposed for multi-needle-induced ionic wind. • Mutual interference of the electric fields between the emitting needles are found and analyzed. • Coupled effects of electric field, flow, and heat transfer for two electrode layouts are analyzed. • Effects of electrode configurations on the cooling performance of the device are investigated. • Optimized ionic wind devices are obtained to ensure electronic components work safely. High temperature during electronic components operation can cause the failure of PN junctions of chips, and it can even damage the entire component. Ionic wind is a promising technique for heat dissipation due to its noiseless, compact structure and flexible design. In this study, needle-ring-type ionic wind devices with multi-needle electrodes connected in parallel are developed for cooling an electronic component. The effects of the number of needles, needle electrode material (tungsten and stainless steel), inter-electrode distance on the device output velocity and cooling performance are experimentally studied for a cylindrical heat sink mounted with a heating film. A full three-dimensional multi-physical numerical method, in which the coupled effects of the electric field, air flow, and heat transfer are considered, is also established. Mutual interference of the electric fields is identified between needle electrodes. The ionic wind velocity is determined by electric field strength and the angle between the ring axis and the line that connects the needle tip and the upper edge of the ring. The wind velocity first decreases and then increases with continuously increasing inter-electrode distance. Although the electrode material has an obvious effect on the ionic wind velocity of the free flow state, the heating film surface temperature is not sensitive to the needle material, whereas it is sensitive to the inter-electrode distance and the number of needles. The output wind velocity of the four-needle layout is larger than that of the three-needle layout despite backflow inside the ring. The heating film surface temperature is below 55 °C for the two designed electrode layouts, which is lower than the safety temperature of 70 °C. This study can serve as a guideline for developing multi-electrode ionic wind cooling systems. [ABSTRACT FROM AUTHOR]

This study focused on the buckling of corroded spherical shells with wall-thickness reduction in local regions under a uniform external pressure. For spherical shells whose wall thickness was reduced owing to local corrosion on the outer surface, the effects of the shape, area, depth, and location of the reduction on the buckling properties were evaluated to identify the most dangerous case. Accordingly, the load-carrying capacity of corroded spherical shells with local reduction was predicted. Moreover, by verifying the five buckling prediction formulas of the spherical shells, reasonable prediction formulas for the compressive capacity of the spherical shells under the condition of corrosion defects were obtained. Four scale models were fabricated using resin material for testing. The geometric shape and wall thickness of each spherical shell model were measured and compared with those of the ideal model. Then, the buckling load and ultimate collapse mode were determined through a hydrostatic test. The experimental and numerical analysis results were compared to verify the numerical analysis. • Proposed a formula for predicting the compressive load of a corroded spherical shell. • The effects of the shape, area, depth and location of corrosion thinned on the buckling of the opening spherical shell was discussed. • Taking thickness as local corrosion defects, the nonlinear buckling of the opening spherical shells was discussed. • The numerical results of thinned spherical shells agree well with experimental results. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive system-level analysis model for evaluating performance characteristics of a hundred-kilowatt proton exchange membrane fuel cell (PEMFC) test system. Unlike conventional power-focused systems, the test system has a more complex architecture and numerous balance of plants (BOPs). The developed model integrates detailed input-output traits of each system component. The energy efficiency ratio (EER) and energy conversion efficiency (η) are introduced as metrics for assessing net power consumption and conversion capability of the test system. By simulating various operational scenarios (considering temperature, load current, cathode pressure, humidity, and PEMFC power), the model predicts the behaviors of BOPs and energy flow relations. The changing rules of the EER and η are also investigated. An increase in temperature, current, and cathode pressure leads to an improvement in EER. Increasing operating temperature, cathode pressure, and humidity can enhance η. Key findings suggest optimal conditions for system self-sufficiency include an operating temperature below 90 °C, load current over 1200 mA cm−2, and air humidity under 90%. Furthermore, the PEMFC power is advisable to configure between 50% and 100% of the test system's maximum power. These insights are pivotal for improving the design and functionality of PEMFC testing equipment, further contributing significant advancements to fuel cell technology. • A system-level analysis model for a hundred-kilowatt PEMFC test system is developed. • The system model contributes to predict operating and energy flow parameters. • Two system indicators are proposed to assess the test system operating performance. • The necessary conditions for the test system to achieve self-sufficiency is determined. [ABSTRACT FROM AUTHOR]

Direct CO 2 electroreduction of flue gas is a technology that simplifies CO 2 capture and purification process and directly utilizes CO 2 in flue gas. Low CO 2 reduction reaction selectivity caused by the low CO 2 partial pressure and side reactions competition is the challenge. In this study, a direct CO 2 electroreduction system for multicomponent flue gases was established. A two-dimensional steady model was developed by considering major electrode reactions of flue gas in Cu x O-based catalysts. General influence criteria and optimum operation window for the potential, temperature, and pressure were proposed. In addition, a techno-economic analysis of the flue gas electrolysis system was conducted. The results demonstrated that the CO 2 electroreduction reaction performances are weak at atmospheric pressure owing to the side reaction competition and small reactant concentration. A method involving pressurization and catholyte inlet temperature declination is proposed to break the stalemate of tiny reactant concentrations and ensure the dominance of the CO 2 electroreduction reaction. The selectivity and current density of the CO 2 reduction reaction were 71% and − 148 mA/cm2 at −1.17 V vs. reversible hydrogen electrode potential (RHE), respectively, under the conditions of an inlet electrolyte temperature of 273 K and an operating pressure of 20 atm. C 1 products with excellent yields are the dominant products. Furthermore, the techno-economic analysis showed that the flue gas electrolysis system has higher profitability and lower cost than the purified CO 2 electrolysis system. The present results can be used to optimize the electrolyzer operating parameters and construct CO 2 reduction systems. • Direct CO 2 electroreduction system for multicomponent flue gas is established. • Performance and electrochemical conditions of flue gas electrolysis are analyzed. • Pressurization and temperature control are proposed to improve flue gas electrolysis. • Flue gas electrolysis is more economic and lucrative than purified CO 2 electrolysis. [ABSTRACT FROM AUTHOR]

The serious colored effluent pollution and high production costs generate new requirements of enhancing dye utilization and reducing energy consumption in reactive dyeing of cotton. A vacuum-dehydration aided pad-steam process with high dye utilization and energy efficiency potential to dye cotton fabric with reactive dye was preliminarily trialed on this purpose. The effects of steaming time, sodium carbonate amount and dye concentration on reactive dyeing were investigated. The color build-up property and rubbing fastness of dyed fabrics were also analyzed. The results show that the steaming time of 3 min and 30 g/L of sodium carbonate were appropriate for dyeing cotton fabric with 25 g/L of C. I. Reactive Black 5. The dye penetration into cotton fibers became poor with increasing dye concentration. Cotton fabrics dyed with the vacuum-dehydration aided pad-steam process had maximum 12% higher K/S value than the fabrics dyed with the conventional pad-steam process, meaning that fewer quantities of dyes could produce higher color strength, which is beneficial to the environmental protection, saving dyes and lowering costs. Rubbing fastness ratings of the dyed fabrics reached equal to or above 3 using the proposed dyeing process, which is suitable for the end use of the fabric. [ABSTRACT FROM AUTHOR]

Energy efficiency evaluation of natural draft wet cooling towers (NDWCTs) is essential to the energy saving process. There is a lack of comprehensive methods that can evaluate and grade the NDWCTs energy efficiency quantitatively. In this study, a comprehensive energy efficiency assessment indicator (CEEAI) including thermal performance, water conservation, and electric saving aspects is proposed. The CEEAI is based on the analysis of NDWCTs mass and heat transfer mechanism. Total 48 actual test reports of the NDWCTs whose water flow rate changes from thousands to hundred thousand tons per hour for test period spans of 16 years, are collected as the database. The CEEAI is validated through statistical analysis and thermodynamics law. Based on the CEEAI and database, an energy-efficiency grading criteria is proposed, the NDWCTs are graded into high, middle and low energy efficiency. Therefore, the energy efficiency of one NDWCT can be clearly observed, which is beneficial for the common researchers to understand the energy efficiency level among all the NDWCTs. In addition, through comparing the CEEAI of different NDWCTs, the energy efficiency gap can be obtained, which provides the optimization guidelines and theoretical support for the improvement of the overall energy efficiency level for the NDWCTs. • A comprehensive energy evaluation assessment indicator for NDWCT was developed. • 48 NDWCTs actual test reports with various size and years was collected as database. • The proposed indicator was verified by statistical and thermodynamic analysis. • An energy-efficiency grading criteria was proposed based on indicator and database. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni sample with different twin boundary orientation was created by FIB, and their effect on mechanical properties was revealed by in situ TEM. • The sample with a twin boundary vertical to the tensile direction achieved high tensile uniform elongation (120%). • Dislocation interaction before reaching the perpendicular CTB contribute to cross-slip and in situ formation of dislocation jogs. The construction of twin boundaries (TBs) in materials is a remarkable way of promoting their strength and ductility. However, the effects of TB orientation on the mechanical properties have not been reported experimentally so far. Using a state-of-the-art in situ tensile stage equipped in a transmission electron microscope, uniaxial tensile tests were performed on three single-crystalline Ni samples with TB parallel and perpendicular to the tensile direction and no TB. The results showed that the uniform tensile elongation strongly depends on TB, 120% for the perpendicular TB sample, 99% for the parallel TB sample, and only 55% for the no TB sample. In addition, dislocation interaction before reaching the perpendicular CTB contribute to cross-slip and dynamic formation of dislocation jogs, thereby improving strain hardening and resulting in a large uniform tensile elongation. [ABSTRACT FROM AUTHOR]

• A novel airfoil flow field is proposed for fuel cells. • Airfoil flow field can enhance mass transfer while maintain low pressure drop. • Fuel cell with airfoil flow field is evaluated via experimental test and simulation. • Airfoil flow field increases the fuel cell's maximum power density effectively. • Airfoil flow field promotes the uniform distributions in fuel cells. Optimal configuration of bipolar plate (BP) embedding flow field is of great significance in improving the power density and durability of proton exchange membrane fuel cells (PEMFCs). Inspired by the airfoil in aircraft dividing the airflow into two streams causing pressure difference, a novel airfoil flow field (AFF) is designed to enhance the mass transfer capacity in channel and across the rib between two adjacent channels, which hardly increases the pressure drop in channel, unlike many baffle designs. The performance improvement achieved by implementing AFF in PEMFC is compared with common parallel flow field (PFF) and the wave flow field (WFF) by experimental test with respect to polarization curve and electrochemical loss and numerical simulation via a three-dimensional (3D) PEMFC model. The experimental results indicate that the novel AFF exhibits best fuel cell performance at various operation conditions (e.g. relative humidity, air stoichiometric ratio) mainly benefitted from the enhanced oxygen transfer, which contributes to the improvement of maximum power density by 8.85 % and 14.37 % compared to PFF and WFF, respectively. The modeling results indicate that the pressure drop increase in AFF is negligible compared with PFF, and is even slightly lower than WFF, indicating high practicability. Moreover, the utilization of AFF also helps the uniformity of oxygen concentration, current density and temperature in PEMFC. [ABSTRACT FROM AUTHOR]

Abstract: Cellular eutectic microstructures with fully lamellar morphology were observed in the directionally solidified Ni–31Al–32Cr–6Mo (at%) hypereutectic alloy at withdrawal rates of 15, 25 and 50μm/s, but the morphologies of cellular microstructures did not change consecutively with increasing withdrawal rate. The growth interfaces were deep cellular at withdrawal rates of 15 and 50μm/s, but it changed to be shallow cellular at rate of 25μm/s. The reason is that the interface undercooling comes to minimum at the middle rate of 25μm/s. If the interface undercooling decreases, the tendency of constitutional undercooling will be weaken. The small constitutional undercooling will increase the interface stability, so that the interface morphology changes from deep cellular to shallow cellular. The shallow cellular growth interface led to a perfect cellular eutectic microstructure, which was analogous to the planar eutectic microstructure. In this case, the widths of the intercellular regions were narrowest, no coarse or irregular plates existed at the cell boundaries, and the thicknesses of the lamellae were almost uniform. The properties of the alloy may be markedly improved. [Copyright &y& Elsevier]

Abstract: Solidification microstructure and growth interface morphology of directionally solidified Ni–31Al–32Cr–6Mo(at.%) hypereutectic alloy were studied. The experiments were carried out at higher temperature gradient of about 250 K cm−1 with different withdrawal rates of 4–500 μm s−1. When the withdrawal rate was less than 50 μm s−1, the primary Cr(Mo) dendrites were gradually eliminated through competitive growth between the primary phase and the eutectic phase. When the withdrawal rate exceeded 100 μm s−1, no primary phase formed, eutectic phase grew directly. Fully eutectic microstructures with lamellar morphology were observed at all withdrawal rates. With increasing withdrawal rate V, the growth interface changed from planar to cellular and then dendritic, the solidification microstructure also transformed from planar eutectic to two-phase cellular eutectic and dendritic eutectic. The microstructure was refined and the eutectic interlamellar spacing λ decreased according to the relationship of λ = 4.82V −0.42. Compared to the alloy at eutectic composition, the volume fraction of Cr(Mo) strengthening phase was increased obviously. [Copyright &y& Elsevier]

Previous molecular simulations and experiments suggest that grain boundaries (GBs) serve as dislocation sources in nanocrystalline metals. Although a large number of studies have been carried out, direct experimental evidence of dislocation nucleation from GBs has rarely been achieved. In this work, we performed in situ transmission electron microscopy (TEM) observations for a Pt nanocrystalline film with an average grain size of ~10 nm during tensile deformation. This study revealed direct evidence of dislocation nucleation at the GBs at the atomic scale. This is different from the common hypothesis predicted by molecular dynamic simulations that only partial dislocations are emitted from GBs in small-grained structures. [Display omitted] • The atomic-scale plastic deformation mechanism in a nano Pt film with a mean grain size of 10 nm were studied by in situ TEM. • The dislocation nucleation at grain boundaries was directly revealed at the atomic scale. • The dislocations were identified to be full dislocations. [ABSTRACT FROM AUTHOR]

Natural polymer hydrogels are expected to be promising biomaterial because of its excellent biocompatibility and biodegradability, but they are soft and easily broken. Herein, the poly (γ-glutamic acid) (γ-PGA)/bacterial cellulose (BC) composite hydrogels with excellent mechanical properties were constructed by introducing bacterial cellulose. The γ-PGA/BC composite hydrogels were obtained by the covalent cross-linking of γ-PGA in the BC nanofibers suspensions. The γ-PGA/BC composite hydrogels exhibited excellent strength and toughness due to the more effective energy dissipation of hydrogen bonds network among BC nanofibers and γ-PGA hydrogel matrix and BC also acts as an enhancer. The compressive fracture strength and toughness of the γ-PGA/BC composite hydrogels could reach up to 5.72 MPa and 0.42 MJ/m3 respectively. Additionally, the tensile strength of γ-PGA/BC composite hydrogels were improved 8.16 times compared with γ-PGA single network hydrogels. More significantly, BC could disperse evenly in the γ-PGA hydrogels because of the hydrophilic nature of γ-PGA and BC nanofillers, which led to good interface compatibility. The result of cytotoxicity tests indicated that γ-PGA/BC composite hydrogels present excellent cytocompatibility, which suggested that the γ-PGA/BC composite hydrogels could serve as promising materials for many biomaterial related applications. Unlabelled Image • The γ-PGA/BC composite hydrogels exhibit excellent strength, toughness and cytocompatibility. • Bacterial cellulose nanofibers acted as both nanofillers and physical cross-linkers in the composite hydrogels. • Two methods of labeling were used to characterize the dispersion uniformity of bacterial cellulose nanofibers in hydrogels. [ABSTRACT FROM AUTHOR]

The enhancement of airside heat transfer in fin-and-tube heat exchanger is crucial for reducing the pumping power, saving materials and so on. In this paper, the authors propose to arrange the winglets radiantly around the tubes on the fin to enhance the airside heat transfer in fin-and-tube heat exchanger. The airside flow and heat transfer characteristic are numerically investigated. The position and the geometric dimensions of the vortex generators are also optimized. The simulation results show that the Colburn j -factor and the friction factor f both increase with VG number. The fin structure has the best comprehensive performance when its VGs are uniformly arranged both in the upwind and backwind regions of the tubes, and at the same time make the enhanced zones the widest in the tube radial direction. With the increase of the VG length, the comprehensive performance factor JF gets lower. The comprehensive performance of the proposed fin with five rows of tubes are demonstrated to be better than a reference fin used in industry with the same fin thickness, tube diameter, fin pitch and tube pitch. [ABSTRACT FROM AUTHOR]

• Silk fibroin-based hydrogel was prepared by the ultrasonic method for hypertrophic scars treatment. • Silk fibroin-based hydrogel was biocompatible with high cell viability on L929 cells. • Silk fibroin-based hydrogel reduced scar thickness and whitened scar color. • The density and arrangement of collagen fibers in scar tissues were improved. • Therapeutic effects of silk fibroin-based hydrogel could be due to the reduction of α-smooth muscle actin. Current medications for the treatment of hypertrophic scars suffer from bottlenecks of limited therapeutic efficacy and a slow recovery rate. Silk fibroin (SF) has gained attention for its ability to promote wound healing in burns and cutaneous wounds, but its therapeutic effects against hypertrophic scar have not been thoroughly investigated. We prepared SF-based hydrogels (SFHs) with various SF concentrations (1.5 %, 3 %, and 6 %) and characterized their physicochemical properties. Cell experiments showed that these SFHs had favorable biocompatibility in vitro. Further animal experiments in rabbits revealed that the SFH (3 %)-treated group achieved scars on their ears that were thinner and significantly lighter in color compared with the negative control group. Moreover, treatment with SFHs reduced the density and led to the orderly arrangement of collagen fibers. It was found that the therapeutic effects of SFHs were attributed to the reduced expression levels of α-smooth muscle actin. These results are the first to demonstrate that SFH can be exploited as an effective therapeutic agent for the treatment of hypertrophic scars. [ABSTRACT FROM AUTHOR]

To quickly optimize the cooling performance of three-dimensional coolant channels in a proton exchange membrane fuel (PEMFC) cell, a generative adversarial network (GAN) model that adopts small-scale sample data to predict the coolant channel topology structure is constructed. The coordinate information of the topological pseudo-density field is directionally input into the neural network to improve prediction accuracy. The results show that more microtopologies in the coolant channels can be predicted with the GAN model than with traditional thermal–fluid–structural topology optimization. The topological configuration with a maximum temperature of 0.15 K, lower than the training dataset, is achieved. The well-trained GAN model can generate topological structures for the optimization objective, that is, thermal performance superior to the training set. The proposed model can also generate topological structures with better fluid and structural performance, which is 20.44% and 9.25% superior to that of the training dataset, respectively. The computation time required by the GAN model is <1 s, while the computation time for the same case is 30.2 h using the traditional thermal–fluid–structural topology optimization. These findings can aid in designing coolant channels in PEMFCs. • Deep-learning accelerating topology optimization of 3D coolant channel is proposed. • Micro-topologies in coolant channels is well predicted with GAN model. • Topologies with better fluid and structural performance are obtained using GAN model. • Computation time is obviously reduced compared to traditional topology optimization. [ABSTRACT FROM AUTHOR]

• Fiber-based composites integrating porous, resonant and damping structures were prepared. • The composite realizes effective noise absorption through gradient impedance design. • Sound waves can be absorbed more easily by optimizing the composite structure. In order to achieve effective noise absorption by finite thickness fiber-based materials, fiber-based composites integrating porous, resonant and damping structures were prepared in this research. Here, the effects of gradient structure, number of constituent units, nonwovens thickness and micro-perforated membrane fabric (MPMF) arrangement on the noise reduction of the composites were simulated and measured. The results showed that the gradient fiber-based composite has excellent broadband sound absorption effect. Moreover, designing the arrangement of micro-perforated structures in the composite can further improve its noise reduction coefficient (NRC). The fiber-based composite (thickness of 1.34 cm) designed by the algorithm has an NRC of 0.51, which is much higher than other noise reduction products with the same thickness. The multi-layer fiber-based composites have the advantages of strong noise reduction capability, small thickness, simple processing and low manufacturing cost, which can be flexibly applied in various noise reduction fields. [ABSTRACT FROM AUTHOR]