High-performance GaSb planar PN junction detector

This paper examines GaSb short-wavelength infrared detectors employing planar PN junctions. The fabrication was based on the Zn diffusion process and the diffusion temperature was optimized. Characterization revealed a 50% cut-off wavelength of 1.73 μm, a maximum detectivity of 8.73 × 10^(10) cm·Hz^(1/2)/W, and a minimum dark current density of 1.02 × 10^(-5) A/cm^(2).Additionally, a maximum quantum efficiency of 60.3% was achieved. Subsequent optimization of fabrication enabled the realization of a 320 × 256 focal plane array that exhibited satisfactory imaging results. Remarkably, the GaSb planar detectors demonstrated potential in low-cost short wavelength infrared imaging, without requiring material epitaxy or deposition.

Developing super-hydrophobic and corrosion-resistant coating on magnesium-lithium alloy via one-step hydrothermal processing

Formation of super-hydrophobic and corrosion-resistant coatings can provide significant corrosion protection to magnesium alloys.However,it remains a grand challenge to produce such coatings for magnesium-lithium alloys due to their high chemical reactivity.Herein,a one-step hydrothermal processing was developed using a stearic-acid-based precursor medium,which enables the hydrothermal conversion and the formation of low surface energy materials concurrently to produce the super-hydrophobic and corrosion-resistant coating.The multiscale microstructures with nanoscale stacks and microscale spheres on the surface,as well as the through-thickness stearates,lead to the super-hydrophobicity and excellent corrosion resistance of the obtained coating.

Vertical 3D Nanostructures Boost Efficient Hydrogen Production Coupled with Glycerol Oxidation Under Alkaline Conditions

Hydrogen production from electrolytic water is an important sustainable technology to realize renewable energy conversion and carbon neutrality.However,it is limited by the high overpotential of oxygen evolution reaction(OER)at the anode.To reduce the operating voltage of electrolyzer,herein thermodynamically favorable glycerol oxidation reaction(GOR)is proposed to replace the OER.Moreover,vertical Ni O flakes and NiMoNH nanopillars are developed to boost the reaction kinetics of anodic GOR and cathodic hydrogen evolution,respectively.Meanwhile,excluding the explosion risk of mixed H_2/O_(2),a cheap organic membrane is used to replace the expensive anion exchange membrane in the electrolyzer.Impressively,the electrolyzer delivers a remarkable reduction of operation voltage by 280 mV,and exhibits good long-term stability.This work provides a new paradigm of hydrogen production with low cost and good feasibility.

Influence of Wellbore Trajectory on Pressure Drop and Fluid Discharge

An experimental analysis has been conducted to study the process of fluid accumulation for different borehole trajectories.More specifically,five heel angles have been experimentally realized to simulate the borehole trajectory of the sloping section of the formation.The fluid-carrying capacity,pressure drop and fluid discharge volatility have been investigated for these conditions and,accordingly,the relationship between heel angle and wellbore pressure drop fluid-carrying capacity has been determined.The results show that while the reasonable roll angle can increase the pressure loss in the wellbore,it is beneficial to drainage.In terms of pressure loss and liquid-carrying capacity,when the heeling angle is 50°,the latter is increased while the former becomes very high,which indicates that when drilling and completing wells on site,a 50°roll angle should be avoided.It is found that the main reason for the increase of the total pressure drop in the wellbore is the increase of the local pressure loss in the inclined section.From the perspective of drainage stability,when there is heeling in the inclined section of the horizontal well,the fluctuation of the wellbore drainage tends to be enhanced.Through the comparison of the Beggs-Brill(B-B)and Mukherjee-Brill liquid holdup methods,it is found that B-B method better predicts liquid holdup.A new method for calculating the pressure drop in the inclined section in the presence of lateral inclination is obtained by taking into account the pressure drop in the curved section.Through comparison with experimental data,it is found that the error is within 20%,and the prediction accuracy is high.

Optimal Concentration of the Bubble Drainage Agent in Foam Drainage Gas Recovery Applications

Foam drainage is theflow of liquid through the interstitial spaces between bubbles driven by capillarity and grav-ity and resisted by viscous damping.The so-called foam drainage gas recovery technology is a technique tradi-tionally used to mitigate the serious bottom-hole liquid loading in the middle and late stages of gas well production.In this context,determining the optimal concentration of the bubble drainage agent is generally cru-cial for the proper application of this method.In this study,a combination of indoor experiments and theoretical analysis have been used to determine the pressure drop related to the foam-carrying capacity in a representative gasfield.Dynamic and static experiments were designed with a bubble drainage agent concentration varying in the range 0.3%–0.6%.Using thefield formation water data,the optimal soaking agent concentration was obtained and pressure drop test experiments on the foam carrying capacity were conducted accordingly.These tests have revealed that the optimal foam displacement agent concentration is 0.5%,and the foam quality at the optimum concentration is between 0.78–0.98.A theoretical method for calculating the pressure drop at the optimum soak-away concentration based on experimental data has also been introduced.The error of the proposed method is within 15%compared to the experimental measured value,demonstrating that it is highly accurate and simple.

High-performance extended short-wavelength infrared PBn photodetectors based on InAs/GaSb/AlSb superlattices

High performance short-wavelength infrared PBn photodetectors based on InAs/GaSb/AlSb superlattices on GaSb substrate have been demonstrated.At 300 K,the device exhibits a 50%cut-off wavelength of~2.1μm as predicted from the band structure calculation;the device responsivity peaks at 0.85 A/W,corresponding to a quantum efficiency(QE)of 56%for 2.0μm-thick absorption region.The dark current density of 1.03×10^(-3)A/cm^(2)is obtained under 50 mV applied bias.The device exhibits a saturated dark current shot noise limited specific detectivity(D*)of 3.29×1010cm·Hz^(1/2)/W(at a peak responsivity of 2.0μm)under-50 mV applied bias.

The measurement of responsivity of infrared photodetectors using a cavity blackbody

For the measurement of responsivity of an infrared photodetector,the most-used radiation source is a blackbody.In such a measurement system,distance between the blackbody,the photodetector and the aperture diameter are two parameters that contribute most measurement errors.In this work,we describe the configuration of our responsivity measurement system in great detail and present a method to calibrate the distance and aperture diameter.The core of this calibration method is to transfer direct measurements of these two parameters into an extraction procedure by fitting the experiment data to the calculated results.The calibration method is proved experimentally with a commercially extended InGaAs detector at a wide range of blackbody temperature,aperture diameter and distance.Then proof procedures are further extended into a detector fabricated in our laboratory and consistent results were obtained.

基于卷积神经网络的玉米病害识别方法研究

为解决传统的玉米病害识别方法中特征提取主观性强及误识率高的问题,提出利用卷积神经网络对玉米病害进行识别。以玉米病害图像和健康图像共5种类别的玉米图像为研究对象,并采用LeNet模型进行试验。首先,按照8:2的比例为每种玉米病害图像选择训练集和测试集。然后,通过试验组合和对比分析的方法比较不同卷积神经网络结构设置对准确率的影响,选出最佳参数。另外,选用Adam算法代替SGD算法来优化模型,通过指数衰减法调整学习率,将L2正则项添加到交叉癇函数中,并选择Dropout策略和ReLU激励函数。最后,确定了一个10层CNN网络结构。试验结果显示,玉米花叶病、灰斑病、锈病、叶斑病和玉米健康识别率分别为95.83%、90.57%、100%、93.75%,100%,平均识别率达96%,平均计算时间为0.15 s。经试验结果比较,该模型识别效果明显高于传统方法,为玉米病害的防治提供技术支持。

Effects of Cs-substitution and partial reduction on catalytic performance of Keggin-type phosphomolybdic polyoxometalates for selective oxidation of isobutane

The catalytic performance of Cs-substituted phosphomolybdic salts was studied for selective oxidation of isobutane. The results of activity tests revealed that 360 °C was the optimal reaction temperature. It was demonstrated that oxidizing sites not only took dominating part in the activation of isobutane, but also influenced the product distribution. Besides, appropriate Cs addition led to moderate acidity of catalysts, favoring the selectivity to desired products. Furthermore, to obtain partially reduced catalysts, different calcination atmospheres were investigated and certain proportion of Mo^（5＋） produced during calcination was crucial for the redox reaction. The catalyst calcined in N2 showed the highest yield of MAA（7.0%）. Fe-substitution enhanced the activity of catalysts by rapid reoxidation of Mo^（5＋）.

Elucidating the effect of barium halide promoters on La_(2)O_(3)/CaO catalyst for oxidative coupling of methane

The industrialization of oxidative coupling of methane(OCM)is restricted by the low once through yield of C_(2)hydrocarbons.Recently,the halogen-assisted OCM process has been attempted to overcome this issue,but the reaction stability was poor due to the rapid loss of gas-phase halides or molten alkali halides.In this work,the barium salts,particularly barium halides(BaCl_(2)and BaF_(2)),were demonstrated to be efficient promoters to improve the OCM reactivity of La_(2)O_(3)/CaO catalyst by increasing both C_(2)selectivity and C_(2)H_(4)/C_(2)H_(6)ratio,and simultaneously achieving outstanding reaction stability.The promoting mechanism can be understood in two aspects.On the one hand,the introduction of barium salts increased the amount of surface electrophilic oxygen species,serving as the alkaline active sites for selective methane activation.On the other hand,the barium halide additives induced the in-situ formation of methyl halide intermediates facilitating C_(2)H_(6)dehydrogenation,and their intimate contact with catalyst substrate restricted the rapid halogen loss and thereby improved the catalytic stability.This work not only provides a class of efficient OCM catalyst,but also offers a highly stable halogen-assisted reaction strategy.

山区农村公路线形设计浅析

以山区农村公路为研究对象,概述了农村公路线形设计的主要规范,同时从平面线形、纵断面线形以及平、纵组合线形三个方面分析了山区农村公路在线形设计中需要注意的地方,并结合工程实践经验总结了山区农村公路设计中需要考虑的工程造价、协调难度等问题,以供相关农村公路设计人员参考。

交通强国发展背景下的县域“十四五”综合交通规划

以交通强国建设为导向,依托枣庄市台儿庄区综合交通规划,根据台儿庄经济社会发展特点,聚焦优化台儿庄综合交通网络,提升交通服务供给质量,打造综合运输体系,充分发挥交通运输对经济社会支撑保障作用,以供其他县域城市编制综合交通规划参考。

某斜交实心板桥极限承载能力研究

以湖北省五峰土家族自治县某斜交实心板桥为工程背景,考虑混凝土的材料的非线性,分析斜交实心板桥在极限承载状态下的受力状况,同时研究汽车荷载加载过程中结构挠度、应力和裂缝的变化规律。分析结果表明:当汽车荷载达到公路-Ⅱ级的60%时,斜交实心板桥的结构受力进入非线性;当汽车荷载达到公路-Ⅱ级的2.364倍时斜交实心板桥达到极限承载能力,斜交实心板桥具有足够的安全储备;随着荷载的增大,斜交实心板桥的挠度、应力、裂缝宽度最大值均逐渐增大,且存在较为明显的非线性关系;随着荷载的增大,裂缝的顺桥向分布宽度逐渐增大,横桥向分布走向不完全平行于桥梁端部,稍向斜交板钝角方向偏转。

某双孔箱涵结构受力及施工水平影响分析

以某双孔箱涵为例,基于圣维南原理建立其三维空间实体有限元模型,分析了双孔箱涵的受力特征,同时考虑实际施工水平对材料特性进行修正,建立其对比模型,分析了施工水平对双孔箱涵结构受力的影响。计算分析表明:双孔箱涵的第一主应力最大值达到混凝土的抗拉强度标准值,在双孔箱涵的跨中位置下缘和中墙位置的顶、底板上缘容易出现裂缝;施工水平的下降将对双孔箱涵的受力产生较大影响,主要表现在结构变形增大、结构裂缝增多且分布更加广泛。

Sn-decorated CeO_(2) with different morphologies for direct dehydrogenation of ethylbenzene

Three Sn-decorated ceria catalysts with various morphologies(rods,particles,and cubes)were prepared and applied to the direct dehydrogenation of ethylbenzene.Multi-technology characterizations,including X-ray photoelectro n spectroscopy(XPS),H_(2)-tempe rature programmed reduction(H_(2)-TPR),and Raman spectroscopy,prove that the oxygen vacancies are the active sites for ethylbenzene dehydrogenation,which can be regulated by engineering CeO_(2) morphology and enhanced via introducing metal Sn.Given the results of activity test,the catalytic activities for ethylbenzene dehydrogenation over different samples are closely dependent on the amount of oxygen vacancies.The reduced Sn-decorated CeO_(2) catalyst with nanoparticles morphology exhibits better dehydrogenation performance than the other two studied catalysts at 600℃.This work provides an effective approach to regulate the active oxygen vacancies and further enhance the dehydrogenation activities through engineering the surface morphology of the catalyst and introducing suitable additives.

A review of research progress on continuous cropping obstacles

Due to the increasing global population and limited land resources, continuous cropping has become common. However, after a few years of continuous cropping, obstacles often arise that cause soil degeneration, decreased crop yield and quality, and increased disease incidence, resulting in significant economic losses. It is essential to understand the causes and mitigation mechanisms of continuous cropping obstacles(CCOs) and then develop appropriate methods to overcome them. This review systematically summarizes the causes and mitigation measures of soil degradation in continuous cropping through a meta-analysis. It was concluded that not all continuous cropping systems are prone to CCOs. Therefore, it is necessary to grasp the principles governing the occurrence of diseases caused by soilborne pathogens in different cropping systems, consider plant–soil-organisms interactions as a system, scientifically regulate the physical and chemical properties of soils from a systems perspective, and then regulate the structure of microbial food webs in the soil to achieve a reduction in diseases caused by soilborne pathogens and increase crop yield ultimately. This review provides reference data and guidance for addressing this fundamental problem.

Herpetrione, a New Type of PPARα Ligand as a Therapeutic Strategy Against Nonalcoholic Steatohepatitis

Non-alcoholic fatty liver disease, especially nonalcoholic steatohepatitis (NASH), is a leading cause of cirrhosis and liver cancer worldwide;nevertheless, there are no Food and Drug Administration-approved drugs for treating NASH until now. Peroxisome proliferator-activated receptor alpha (PPARα) is an interesting therapeutic target for treating metabolic disorders in the clinic, including NASH. Herpetrione, a natural lignan compound isolated from Tibetan medicine Herpetospermum caudigerum, exerts various hepatoprotective effects, but its efficacy and molecular mechanism in treating NASH have not yet been elucidated. Here, we discovered that herpetrione lessened lipid accumulation and inflammation in hepatocytes stimulated with oleic acid and lipopolysaccharide, and effectively alleviated NASH caused by a high-fat diet or methionine-choline-deficient diet by regulating glucolipid metabolism, insulin resistance, and inflammation. Mechanistically, RNA-sequencing analyses further showed that herpetrione activated PPAR signaling, which was validated by protein expression. Furthermore, the analysis of molecular interactions illustrated that herpetrione bound directly to the PPARα protein, with binding sites extending to the Arm III domain. PPARα deficiency also abrogated the protective effects of herpetrione against NASH, suggesting that herpetrione protects against hepatic steatosis and inflammation by activation of PPARα signaling, thereby alleviating NASH. Our findings shed light on the efficacy of a natural product for treating NASH, as well as the broader prospects for NASH treatment by targeting PPARα.

Reproductive toxicity of enrofloxacin in Caenorhabditis elegans involves oxidative stress-induced cell apoptosis

Fluoroquinolone antibiotics(FQs)that persist and bioaccumulate in the environment have aroused people’s great concern.Here,we studied the adverse effects of FQs in soil animals of Caenorhabditis elegans via food-chronically exposure.The result shows C.elegans exposed to FQs exhibited reproductive toxicity with small-brood size and low-egg hatchability.To study the underlying mechanism,we conduct a deep investigation of enrofloxacin(ENR),one of the most frequently detected FQs,on nematodes which is one of commonly used animal indicator of soil sustainability.The concentration-effect curves simulated by the Hill model showed that the half effect concentrations(EC50)of ENR were(494.3±272.9)μmol/kg and(107.4±30.9)μmol/kg for the brood size and the hatchability,respectively.Differential gene expression between the control and the ENR-exposure group enriched with the oxidative stress and cell apoptosis pathways.The results together with the enzyme activity in oxidative stress and the cell corpses suggested that ENR-induced reproductive toxicity was related to germ cell apoptosis under oxidative stress.The risk quotients of some soil and livestock samples were calculated based on the threshold value of EC10 for the egg hatchability(2.65μmol/kg).The results indicated that there was possible reproductive toxicity on the nematodes in certain agricultural soils for the FQs.This study suggested that chronic exposure to FQs at certain levels in environment would induce reproductive toxicity to the nematodes and might reduce the soil sustainability,alarming the environment risks of antibiotics abuse.

The stabilization effect of Al_(2)O_(3)on unconventional Pb/SiO_(2)catalyst for propane dehydrogenation

Similar to Sn,Pb located at the same group(IVA)in the periodic table of elements,can also catalyze propane dehydrogenation to propene,while a fast deactivation can be observed.To enhance the stability,the traditional carrier Al_(2)O_(3)with a small amount,was introduced into Pb/SiO_(2)catalyst in this study.It has been proved that Al_(2)O_(3)can inhibit the reduction of PbO,and weaken the agglomeration and loss of Pb species due to its enhanced interaction with Pb species.As a result,3Al15Pb/SiO_(2)catalyst exhibits a much higher stability up to more than 150 h.In addition,a simple schematic diagram of the change of surface species on the catalyst surface after Al_(2)O_(3)addition was also proposed.

飞雁式异形钢箱拱制作线形控制关键技术研究

钢结构桥梁采用大节段分段施工,工厂化预制,板块线形的精确放样是钢结构制作线形精准控制的关键因素。飞雁式异形钢结构拱肋曲线复杂,拱肋截面高度随拱轴线线性变化,给钢结构制作加工带来很大困难。桥梁拱肋设计成桥线形和预拱度线形的理论求解可为后续解决钢结构拱肋顶、底板加工制作,板块精确放样提供理论支持,为成桥后钢结构拱肋受力稳定提供保障。预制钢箱拱拱肋理论制作线形是确保偏态抛物线异形变截面钢箱拱桥顺利安装和桥梁服役阶段受力合理的重要技术指标。通过设计计算软件MIDAS建立桥梁理论计算模型,采用正装分析计算的方法计算出张拉预应力系杆、拆除拱肋安装支架、张拉吊杆、卸除主梁桥下支架、二次张拉吊杆等施工工序转换对拱肋成桥线形的影响,得到钢拱肋在施工、架设期间体系转换的理论预拱度值。再结合设计图纸给出的异形钢箱拱肋拱轴线计算方程式,通过坐标转换的方法,建立拱轴线上任一点O点的坐标系1和拱轴线上无限接近O点的相邻点B的坐标系2,以及全桥原始坐标系三者之间的联系。通过原始坐标系中O点位置坐标(x 1,z 1),B点位置坐标(x 2,z 2)以及O点处的截面高度H之间的关系,结合坐标系1和坐标系2确定出三者之间的三角形相似关联,从而求得成桥状态下异形钢箱拱肋制作的顶、底板,横隔板及吊杆与拱轴线计算方程式之间的几何关系,确定出钢箱拱拱肋顶、底板独立的成桥线形的计算方程式。运用此计算式求出的拱肋成桥曲线与设计院给出的设计线形吻合良好,当x 2-x 1=0.5 m时计算线形与成桥线形的最大偏差为2 mm,证明了此种方式的正确性。再通过成桥状态下的计算式,结合MIDAS模型计算出的拱肋曲线各点的预拱度值,求解出钢结构拱肋无应力状态下顶、底板,横隔板;吊杆的计算方程式。此计算方程式确定出的曲线状态就是钢拱肋无应力状态下线形,运用此计算结果求得的无应力状态曲线比成桥设计线形长出80 mm。此计算方法有效地解决了异形钢箱拱肋工厂预制过程中无应力状态板块线形精确放样的难题。