Mechanism of microarc oxidation on AZ91D Mg alloy induced byβ-Mg_(17)Al_(12) phase

This work proposed a strategy of indirectly inducing uniform microarc discharge by controlling the content and distribution ofβ-Mg_(17)Al_(12)phase in AZ91D Mg alloy.Two kinds of nano-particles(ZrO_(2)and TiO_(2))were designed to be added into the substrate of Mg alloy by friction stir processing(FSP).Then,Mg alloy sample designed with different precipitated morphology ofβ-Mg_(17)Al_(12)phase was treated by microarc oxidation(MAO)in Na_(3)PO_(4)/Na2SiO3electrolyte.The characteristics and performance of the MAO coating was analyzed using scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),contact angle meter,and potentiodynamic polarization.It was found that the coarseα-Mg grains in extruded AZ91D Mg alloy were refined by FSP,and theβ-Mg_(17)Al_(12)phase with reticular structure was broken and dispersed.The nano-ZrO_(2)particles were pinned at the grain boundary by FSP,which refined theα-Mg grain and promoted the precipitation ofβ-Mg_(17)Al_(12)phase in grains.It effectively inhibited the“cascade”phenomenon of microarcs,which induced the uniform distribution of discharge pores.The MAO coating on Zr-FSP sample had good wettability and corrosion resistance.However,TiO_(2)particles were hardly detected in the coating on TiFSP sample.

老年营养风险指数与卒中后认知障碍的关系

目的:营养状况是否与卒中后认知功能障碍(post-stroke cognitive impairment,PSCI)相关尚不清楚。本研究的目的是确定老年营养风险指数(geriatric nutritional risk index,GNRI)评估患者的发病时营养状况与急性缺血性脑卒中3个月后PSCI发生之间的关系。方法:共有45例急性缺血性脑卒中后认知障碍患者被纳入PSCI组,同时随机纳入同期急性缺血性脑卒中未发生PSCI的患者45例为NCI组。GNRI计算公式为1.489×血清白蛋白(g/L)+41.7×入院体重(kg)/理想体重(kg),并根据预先设定的无营养不良风险和存在营养不良风险的分界点进行二分。采用二元逻辑回归和线性回归分析来调查GNRI是否为PSCI的影响因素。结果:纳入卒中后3个月发生PSCI的患者45例,GNRI平均分为(99.31±8.58)分,19例患者(42.2%)GNRI水平低于98分。在控制了高密度脂蛋白因素的影响后,GNRI与PSCI独立相关(OR=0.946,P=0.046)。结论:低GNRI水平与缺血性卒中后3个月PSCI的发生独立相关。

Insight into the experiment and extraction mechanism for separating carbazole from anthracene oil with quaternary ammonium-based deep eutectic solvents

Carbazole is an irreplaceable basic organic chemical raw material and intermediate in industry.The separation of carbazole from anthracene oil by environmental benign solvents is important but still a challenge in chemical engineering.Deep eutectic solvents (DESs) as a sustainable green separation solvent have been proposed for the separation of carbazole from model anthracene oil.In this research,three quaternary ammonium-based DESs were prepared using ethylene glycol (EG) as hydrogen bond donor and tetrabutylammonium chloride (TBAC),tetrabutylammonium bromide or choline chloride as hydrogen bond acceptors.To explore their extraction performance of carbazole,the conductor-like screening model for real solvents (COSMO-RS) model was used to predict the activity coefficient at infinite dilution (γ^(∞)) of carbazole in DESs,and the result indicated TBAC:EG (1:2) had the stronger extraction ability for carbazole due to the higher capacity at infinite dilution (C^(∞)) value.Then,the separation performance of these three DESs was evaluated by experiments,and the experimental results were in good agreement with the COSMO-RS prediction results.The TBAC:EG (1:2) was determined as the most promising solvent.Additionally,the extraction conditions of TBAC:EG (1:2) were optimized,and the extraction efficiency,distribution coefficient and selectivity of carbazole could reach up to 85.74%,30.18 and 66.10%,respectively.Moreover,the TBAC:EG (1:2) could be recycled by using environmentally friendly water as antisolvent.In addition,the separation performance of TBAC:EG (1:2) was also evaluated by real crude anthracene,the carbazole was obtained with purity and yield of 85.32%,60.27%,respectively.Lastly,the extraction mechanism was elucidated byσ-profiles and interaction energy analysis.Theoretical calculation results showed that the main driving force for the extraction process was the hydrogen bonding ((N–H...Cl) and van der Waals interactions (C–H...O and C–H...π),which corresponding to the blue and green isosurfaces in IGMH analysis.This work presented a novel method for separating carbazole from crude anthracene oil,and will provide an important reference for the separation of other high value-added products from coal tar.

Bionic lightweight design of limb leg units for hydraulic quadruped robots by additive manufacturing and topology optimization

Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large payloads.As the most critical movement unit of a quadruped robot,the limb leg unit(LLU)directly affects movement speed and reliability,and requires a compact and lightweight design.Inspired by the dexterous skeleton–muscle systems of cheetahs and humans,this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an LLU.We propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing,and hybrid lattice structures are introduced into the lightweight design of the piston rod.In addition,additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the LLU.The mechanical properties of the actuator system are verified by numerical simulation and experiments,and the power density of the actuators is far greater than that of cheetah muscle.The mass of the optimized LLU is reduced by 24.5%,and the optimized LLU shows better response time performance when given a step signal,and presents a good trajectory tracking ability with the increase in motion frequency.

Synergistic CO_(2) mineralization using coal fly ash and red mud as a composite system

CO_(2) mineralization plays a critical role in the storage and utilization of CO_(2).Coal fly ash(CFA)and red mud(RM)are widely utilized as CO_(2) mineralizers.However,the inert calcium species in CFA limit its carbonation capacity,meanwhile the substantial Ca^(2+)releasing of RM is hindered by a covering layer of calcium carbonate.In this study,CO_(2) mineralization in a composite system of CFA and RM was investigated to enhance the carbonation capacity.Multiple analyzers were employed to characterize the raw materials and resulting mineralization products.The results demonstrated that a synergistic effect existed in the composite system of CFA and RM,resulting in improving CO_(2) mineralization rate and efficiency.The produced calcium carbonate was ectopically attached the surface of CFA in the composite system,thus slowing down its coverage on the surface of RM.This phenomenon facilitated further releasing Ca^(2+)from the internal RM,thereby enhancing CO_(2) mineralization efficiency.Meanwhile,the inclusion of RM significantly improved the alkalinity of the composite system,which not only promoted the dissolution of Ca^(2+)of the inert CaSO_(4)(H_(2)O)_(2) in CFA,but also accelerated CO_(2) mineralization rate.The investigation would be beneficial to CO_(2) mineralization using industrial solid wastes.

Review on current development of polybenzimidazole membrane for lithium battery

With the rapid development of portable technology,lithium batteries have emerged as potential candidates for high-performance energy storage systems owing to their high energy density and cycling stability.Among the key components of a lithium battery system,the separator plays a critical role as it directly influences the battery performance benchmark(cycling performance and safety).However,traditional polyolefin separators(polypropylene/polyethylene)are unable to meet the demands of highperformance and safer battery systems due to their poor electrolyte compatibility,thermal runaways,and ultimate growth of dendrites.In contrast,membranes fabricated using polybenzimidazole(PBI)exhibit excellent electrolyte wettability and outstanding thermal dimensional stability,thus holding great potential as separators for high-performance and high-safety batteries.In this paper,we present a comprehensive review of the general requirements for separators,synthesis technology for separators,and research trends focusing PBI membranes in lithium batteries to alleviate the current commercial challenges faced by conventional polyolefin separators.In addition,we discuss the future development direction for PBI battery separators by considering various factors such as production cost,ecological footprint,preparation technology,and battery component compatibility.By exploring these perspectives,we aim to promote the continued application and exploration of PBI-based materials to advance lithium battery technology.

Construction of LSPR-enhanced 0D/2D CdS/MoO3‒x S-scheme heterojunctions for visible-light-driven photocatalytic H2 evolution

Plasmonic nonmetal semiconductors with localized surface plasmon resonance(LSPR)effects possess extended light-response ranges and can act as highly efficient H2 generation photocatalysts.Herein,an LSPR-enhanced 0D/2D CdS/MoO3‒x heterojunction has been synthesized by the growth of 0D CdS nanoparticles on 2D plasmonic MoO3‒x elliptical nanosheets via a simple coprecipitation method.Taking advantage of the LSPR effect of the MoO3‒x elliptical nanosheets,the light absorption of the CdS/MoO3‒x heterojunction was extended from 600 nm to the near-infrared region(1400 nm).Furthermore,the introduction of 2D plasmonic MoO3‒x elliptical nanosheets not only provided a platform for the growth of CdS nanoparticles,but also contributed to the construction of an LSPR-enhanced S-scheme structure due to the interface between the MoO3‒x and CdS,accelerating the separation of light-induced electrons and holes.Therefore,the CdS/MoO3‒x heterojunction exhibited higher photocatalytic H2 generation activity than pristine CdS under visible light irradiation,including under 420,450,550,and 650 nm monochromic light,as well as improved photo-corrosion performance.

心功能标志物在认知障碍患者中的作用

目的:近年来,心脏功能在认知功能障碍中的作用成为研究热点,认为心功能下降与认知障碍有关。因此,我们研究了代表心功能的标志物,如每搏输出量(SV)、左室射血分数(LVEF)、N末端B型脑钠肽(NTpro-BNP)等与认知障碍的关联,并试图解释心功能指标在认知障碍患者中的作用及可能机制。方法:纳入认知障碍患者61例以及年龄、性别和文化水平相匹配的认知正常对照组50例,收集一般临床资料,并完成血生化如血脂、同型半胱氨酸(Hcy)、N端-B型钠尿肽前体(NT-proBNP)、游离三碘甲状腺原氨酸(FT3)、游离四碘甲状腺原氨酸(FT4)、三碘甲状腺原氨酸(T3)、甲状腺素(T4)、促甲状腺激素(TSH)、D-二聚体等指标检测,并完成血清NT-proBNP检测。两组患者均完成超声心动图,测量LVEF%、SV、每分搏出量(CO)等指标。结果:认知障碍组患者SV、CO明显低于健康对照组,NT-proBNP水平高于健康对照组,差异有统计学意义(P <0.05),而两组间LVEF%水平差异无统计学意义(P> 0.05);在多变量Logistic回归分析中,校正了体重指数、血管危险因素等影响因素后发现,SV与认知障碍独立相关(OR=0.918,P=0.022)。结论:心功能下降与认知障碍存在相关性,认知障碍患者更易合并有心功能下降,SV下降可能是认知障碍发生的独立危险因素。

冷媒辅助搅拌摩擦处理AZ31B镁合金的显微组织演变及力学性能

传统搅拌摩擦处理(FSP)后的AZ31B镁合金通常表现出强烈的基面织构,导致其强度和塑性匹配较差。本文作者采用冷媒辅助搅拌摩擦处理对AZ31B镁合金进行加工,研究液态二氧化碳冷却剂对搅拌区热循环、显微组织和力学性能的影响。使用液态二氧化碳同步冷却法可显著降低搅拌区的峰值温度并提高冷却速度,搅拌区出现具有大量位错和■孪晶的细晶结构。在不连续动态再结晶、连续动态再结晶和孪晶诱导几何动态再结晶的综合作用下,搅拌区发生显著的晶粒细化。拉伸试验中由于位错和■孪晶产生的交互作用,搅拌区的极限抗拉强度和断后伸长率分别达293 MPa和18.6%,表现出良好的强度和塑性匹配。

Dealloying of an amorphous TiCuRu alloy results in a nanostructured electrocatalyst for hydrogen evolution reaction

Development of an electrocatalyst that is cheap and has good properties to replace conventional noble metals is important for H_(2) applications.In this study,dealloying of an amorphous Ti_(37)Cu_(60)Ru_(3) alloy was performed to prepare a freestanding nanostructured hydrogen evolution reaction(HER)catalyst.The effect of dealloying and addition of Ru to TiCu alloys on the microstructure and HER properties under alkaline conditions was investigated.3 at.%Ru addition in Ti_(40)Cu_(60) decreases the overpotential to reach a current density of 10mA cm^(-2) and Tafel slope of the dealloyed samples to 35 and 34mV dec−1.The improvement of electrocatalytic properties was attributed to the formation of a nanostructure and the modification of the electronic structure of the catalyst.First-principles calculations based on density function theory indicate that Ru decreases the Gibbs free energy of water dissociation.This work presents a method to prepare an efficient electrocatalyst via dealloying of amorphous alloys.

ScRNA-seq reveals the correlation between M2 phenotype of tumorassociated macrophages and lymph node metastasis of breast cancer

The process of lymphatic metastasis was proved to be associated with podoplanin-expressing macrophages in breast cancer(BC).This study aimed to investigate the role of the M2 phenotype of tumor-associated macrophages and mine the key M2 macrophages-related genes for lymph node metastasis in BC.We downloaded the GSE158399 dataset from the Gene Expression Omnibus(GEO)database,which includes transcriptomic profiles of individual cells from primary tumors,negative lymph nodes(NLNs),and positive lymph nodes(PLNs)of breast cancer patients.The cell subsets were identified by clustering analysis after quality control of the scRNA-seq using Seurat.The activation and migration capability of M2 macrophages were evaluated with R package“GSVA”.The key M2 macrophages-related genes were screened from the differential expressed genes(DEGs)and M2 macrophages activation and migration gene sets collected from MSigDB database.Our analysis identified three main cell types in primary tumors,NLNs,and PLNs:basal cells,luminal cells,and immune cell subsets.The further cell type classification of immune cell subsets indicated M2 macrophages accumulation in NLs and PLs.The GSVA enrichment scores for activation and migration capability were increased significantly in M2 macrophages from primary tumors than NLNs and PLNs(pvalue<0.001).Seven M2 macrophages activation-related and 15 M2 macrophages migration-related genes were significantly up-regulated in primary tumors than NLNs and PLNs.The proportion and GSVA enrichment scores for activation and migration of M2 macrophages may be potential markers for lymph node metastasis in breast cancer.Our study demonstrated that twenty-two up-regulated mRNA may be possible therapeutic targets for lymph node metastasis in breast cancer.

Insight into the green route to dimethyl succinate by direct esterification of bio-based disodium succinate using CO_(2)and CH_(3)OH

The fermentation for succinic acid production outperforms other methods by low energy consumption and environmental benignity,with the resulting products mainly as disodium succinate(DSA).By directly esterifying DSA using CO_(2) and CH3OH,it is expected to avoid the use of inorganic acids.By high-resolution mass spectrometry analysis and theoretical calculation,this study establishes that the reaction consists of three steps,i.e.,first forming 3-carboxypropanoate,then monomethyl succinate(MMS),and finally dimethyl succinate(DMS).A detailed kinetic analysis is further performed,the results demonstrate that the transformation of DSA to MMS is regarded to be a second-order reaction for reactant DSA,while the transformation of MMS to DMS is a first-order reaction for reactant MMS.The activation energy for the generation of MMS from DSA is 37.15 kJ·mol^(-1),and that for the generation of DMS from MMS is 85.80 kJ·mol^(-1),indicating the latter one is the rate-determining step.

An integrated and cooperative architecture for multi-intersection traffic signal control

Traffic signal control(TSC)systems are one essential component in intelligent transport systems.However,relevant studies are usually independent of the urban traffic simulation environment,collaborative TSC algorithms and traffic signal communication.In this paper,we propose(1)an integrated and cooperative Internet-of-Things architecture,namely General City Traffic Computing System(GCTCS),which simultaneously leverages an urban traffic simulation environment,TSC algorithms,and traffic signal communication;and(2)a general multi-agent reinforcement learning algorithm,namely General-MARL,considering cooperation and communication between traffic lights for multi-intersection TSC.In experiments,we demonstrate that the integrated and cooperative architecture of GCTCS is much closer to the real-life traffic environment.The General-MARL increases the average movement speed of vehicles in traffic by 23.2%while decreases the network latency by 11.7%.

Research and Development of Electro‑hydraulic Control Valves Oriented to Industry 4.0:A Review

Electro-hydraulic control valves are key hydraulic components for industrial applications and aerospace,which controls electro-hydraulic motion.With the development of automation,digital technology,and communication technology,electro-hydraulic control valves are becoming more digital,integrated,and intelligent in order to meet the requirements of Industry 4.0.This paper reviews the state of the art development for electro-hydraulic control valves and their related technologies.This review paper considers three aspects of state acquisition through sensors or indirect acquisition technologies,control strategies along with digital controllers and novel valves,and online maintenance through data interaction and fault diagnosis.The main features and development trends of electro-hydraulic control valves oriented to Industry 4.0 are discussed.

Radiomics model based on preoperative gadoxetic acid-enhanced MRI for predicting liver failure

BACKGROUND Postoperative liver failure is the most severe complication in cirrhotic patients with hepatocellular carcinoma(HCC) after major hepatectomy. Current available clinical indexes predicting postoperative residual liver function are not sufficiently accurate.AIM To determine a radiomics model based on preoperative gadoxetic acid-enhanced magnetic resonance imaging for predicting liver failure in cirrhotic patients with HCC after major hepatectomy.METHODS For this retrospective study, a radiomics-based model was developed based on preoperative hepatobiliary phase gadoxetic acid-enhanced magnetic resonance images in 101 patients with HCC between June 2012 and June 2018. Sixty-one radiomic features were extracted from hepatobiliary phase images and selected by the least absolute shrinkage and selection operator method to construct a radiomics signature. A clinical prediction model, and radiomics-based model incorporating significant clinical indexes and radiomics signature were built using multivariable logistic regression analysis. The integrated radiomics-based model was presented as a radiomics nomogram. The performances of clinical prediction model, radiomics signature, and radiomics-based model for predicting post-operative liver failure were determined using receiver operating characteristics curve, calibration curve, and decision curve analyses.RESULTS Five radiomics features from hepatobiliary phase images were selected to construct the radiomics signature. The clinical prediction model, radiomics signature, and radiomics-based model incorporating indocyanine green clearance rate at 15 min and radiomics signature showed favorable performance for predicting postoperative liver failure(area under the curve: 0.809-0.894). The radiomics-based model achieved the highest performance for predicting liver failure(area under the curve: 0.894;95%CI: 0.823-0.964). The integrated discrimination improvement analysis showed a significant improvement in the accuracy of liver failure prediction when radiomics signature was added to the clinical prediction model(integrated discrimination improvement = 0.117, P =0.002). The calibration curve and an insignificant Hosmer-Lemeshow test statistic(P = 0.841) demonstrated good calibration of the radiomics-based model. The decision curve analysis showed that patients would benefit more from a radiomics-based prediction model than from a clinical prediction model and radiomics signature alone.CONCLUSION A radiomics-based model of preoperative gadoxetic acid–enhanced MRI can be used to predict liver failure in cirrhotic patients with HCC after major hepatectomy.

Effects of aging treatment and heat input on the microstructures and mechanical properties of TIG-welded 6061-T6 alloy joints

Aging treatment and various heat input conditions and mechanical properties of TIG welded 606I-T6 alloy joints were adopted to investigate the microstructural evolution by microstructural observations, microhardness tests, and tensile tests. With an increase in heat input, the width of the heat-affected zone （HAZ） increases and grains in the fusion zone （FZ） coarsen. Moreover, the hardness of the HAZ decreases, whereas that of the FZ decreases initially and then increases with an increase in heat input. Low heat input results in the low ultimate tensile strength of the welded joints due to the presence of partial penetrations and pores in the welded joints. After a simple artificial aging treatment at 175℃ for 8 h, the microstructure of the welded joints changes slightly. The mechanical properties of the welded joints enhance significantly after the aging process as few precipitates distribute in the welded seam.

Influence of heat treatment on microstructure and mechanical properties of FeCrNi coating produced by laser cladding

The FeCrNi alloy powders were used on the dovetail groove of FV520B steel to fabricate the multilayer laser cladding layers. The effects of heat treatment on the microstructure and mechanical properties of FeCrNi layers were investigated. The results showed that the heat treatment at the temperature ranged from 1073 to 1273 K refined the grains of the substrate materials and removed the soft zone of hardness between the fused zone (FZ) and base material (BM) effectively mainly due to a secondary quench of heat treatment. When the temperature of heat treatment was 1073 K, the maximum ultimate tensile strength (UTS) values of the laser cladding component were obtained. However, the heat treatment at high temperature had a bad effect on wear resistance of coatings at some extent.

Microstructure and mechanical properties of TIG/A-TIG welded AZ61/ZK60 magnesium alloy joints

The dissimilar joints of AZ61 and ZK60 magnesium alloys were obtained by tungsten inert gas arc(TIG)welding and activating tungsten inert gas arc(A-TIG)welding processes.Microstructure characterization shows that,the fineα-Mg equiaxed dendrite crystals contained Mg17Al12 and MgZn2 particles in the fusion zone.The average size of theα-Mg grains in the fusion zone was refined to 19μm at welding current of 80 A,which resulted in the largest tensile strength of 207 MPa.The tensile strength and the width of the beam of the A-TIG welded AZ61/ZK60 joints showed strong dependence on the amount of TiO2.However,the inhomogeneity of the heat-affected zone near different base metals presented no significant effect on the mechanical properties of the welded joint.

Accelerating photocatalytic hydrogen evolution and pollutant degradation by coupling organic co-catalysts with TiO_2

Accelerating the separation efficiency of photoexcited electron-hole pairs with the help of highly active co-catalysts has proven to be a promising approach for improving photocatalytic activity. Thus far, the most developed co-catalysts for semiconductor-based photocatalysis are inorganic materials;the employment of a specific organic molecule as a co-catalyst for photocatalytic hydrogen evolution and pollutant photodegradation is rare and still remains a challenging task. Herein, we report on the use of an organic molecule, oxamide (OA), as a novel co-catalyst to enhance electron- hole separation, photocatalytic H2 evolution, and dye degradation over TiO2 nanosheets. OA-modified TiO2 samples were prepared by a wet chemical route and demonstrated improved light absorption in the visible-light region and more efficient charge transport. The photocatalytic performance of H2 evolution from water splitting and rhodamine B (RhB) degradation for an optimal OA-modified TiO2 photocatalyst reached 2.37 mmol g^–1 h^–1 and 1.43 × 10^-2 min^-1, respectively, which were 2.4 and 3.8 times higher than those of pristine TiO2, respectively. A possible mechanism is proposed, in which the specific π-conjugated structure of OA is suggested to play a key role in the enhancement of the charge transfer and catalytic capability of TiO2. This work may provide advanced insight into the development of a variety of metal-free organic molecules as functional co-catalysts for improved solar-to-fuel conversion and environmental remediation.

Parameter optimization for tungsten carbide/Ni-based composite coating deposited by plasma transferred arc hardfacing

Ni-based composite coatings with a high content of tungsten carbides(Stelcar65composite coatings)were synthesized by plasma transferred arc(PTA)hardfacing.The welding parameters of Stelcar65composite coatings were optimized by orthogonal tests.The PTA welding parameters including welding current,powder feed rate and welding speed have significant influence on the tungsten carbide degradation.The values for the optimum welding current,powder feed rate and welding speed were determined to be100A,25g/min and40mm/min,respectively.The produced WC/Ni-based composite coatings were crack-and degradation-free.The microstructure of deposited layers,as well as the microstructure and microhardness of the optimal coating were further analyzed.