Behavior of exciton in direct−indirect band gap Al_(x)Ga_(1−x)As crystal lattice quantum wells

Excitons have significant impacts on the properties of semiconductors.They exhibit significantly different properties when a direct semiconductor turns in to an indirect one by doping.Huybrecht variational method is also found to influence the study of exciton ground state energy and ground state binding energy in Al_(x)Ga_(1−x)As semiconductor spherical quantum dots.The Al_(x)Ga_(1−x)As is considered to be a direct semiconductor at AI concentration below 0.45,and an indirect one at the concentration above 0.45.With regards to the former,the ground state binding energy increases and decreases with AI concentration and eigenfrequency,respectively;however,while the ground state energy increases with AI concentration,it is marginally influenced by eigenfrequency.On the other hand,considering the latter,while the ground state binding energy increases with AI concentration,it decreases with eigenfrequency;nevertheless,the ground state energy increases both with AI concentration and eigenfrequency.Hence,for the better practical performance of the semiconductors,the properties of the excitons are suggested to vary by adjusting AI concentration and eigenfrequency.

Omental fibroma combined with right indirect inguinal hernia masquerades as a scrotal tumor: A case report

BACKGROUND The most common causes of scrotal enlargement in patients include primary tumor of the scrotum,inflammation,hydrocele of the tunica vaginalis,and indirect inguinal hernia;scrotal enlargement caused by external tumors of the scrotum is rare.The patient had both a greater omentum tumor and an inguinal hernia,and the tumor protruded into the scrotum through the hernia sac,which is even rarer.Moreover,omental tumors are mostly metastatic,and primary omental fibroma is rare.CASE SUMMARY Here,we report a rare case of a 25-year-old young man with scrotal enlargement and pain for 3 months.Preoperative examination and multidisciplinary discu-ssions considered intra-abdominal tumor displacement and inguinal hernia,and intraoperative exploration confirmed that the greater omentum tumor protruded into the scrotum.Therefore,tumor resection and tension-free inguinal hernia repair were performed.The final diagnosis was benign fibroma of the greater omentum accompanied by an indirect inguinal hernia.CONCLUSION This unusual presentation of a common inguinal hernia disease illustrates the necessity of performing detailed history taking,physical examination,and imaging before surgery.

Experimental Study and Thermal Modelling of Cocoa Shell Convective Drying in an Indirect Solar Dryer

The concern of the present work is the convective drying of empty cocoa shells in an indirect solar dryer. Some drying experiments, using one sample, were carried out. During the experiments, the sample is introduced in the drying chamber. Then at steady time intervals, the sample is withdrawn from the drying chamber, for a rapid weighing. After each weighing, the sample is reintroduced in the dryer. At each time interval, the ambient temperature of the drying chamber and its relative humidity γ are measured by a thermo-hygrometer. From the experimental data, a theoretical determination of the moisture evaporated from the product was performed and a good agreement was found between the theoretical and experimental values, confirmed by the value of the RMSE. Those calculations used the constants in the Nusselt number found in literature. Then those constants were evaluated again, to get new values more suitable with the experimental data. The dimensionless numbers of Nusselt, Grashof and Prandtl were calculated. That allowed the calculation of the average value of the Nusselt number. The average convective heat transfer coefficient was determined.

Indirect Electroanalysis of 3-Methyl-4-Nitrophenol in Water Using Carbon Fiber Microelectrode Modified with Nickel Tetrasulfonated Phthalocyanine Complex

Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use of a carbon fiber microelectrode modified with a tetrasulfonated nickel phthalocyanine complex for the detection of MNP at a lower potential than that of direct phenol oxidation. The MNP voltammogram showed the presence of an anodic peak at -0.11 V vs SCE, corresponding to the oxidation of the hydroxylamine group generated after the reduction of the nitro group. The effect of buffer pH on the peak current and SWV parameters such as frequency, scan increment, and pulse amplitude were studied and optimized to have better electrochemical response of the proposed sensor. With these optimal parameters, the calibration curve shows that the peak current varied linearly as a function of MNP concentration, leading to a limit of detection (LoD) of 1.1 μg/L. These results show an appreciable sensitivity of the sensor for detecting the MNP at relatively low potentials, making it possible to avoid passivation phenomena.

Indirect Vector Control of Linear Induction Motors Using Space Vector Pulse Width Modulation

Vector control schemes have recently been used to drive linear induction motors(LIM)in high-performance applications.This trend promotes the development of precise and efficient control schemes for individual motors.This research aims to present a novel framework for speed and thrust force control of LIM using space vector pulse width modulation(SVPWM)inverters.The framework under consideration is developed in four stages.To begin,MATLAB Simulink was used to develop a detailed mathematical and electromechanical dynamicmodel.The research presents a modified SVPWM inverter control scheme.By tuning the proportional-integral(PI)controller with a transfer function,optimized values for the PI controller are derived.All the subsystems mentioned above are integrated to create a robust simulation of the LIM’s precise speed and thrust force control scheme.The reference speed values were chosen to evaluate the performance of the respective system,and the developed system’s response was verified using various data sets.For the low-speed range,a reference value of 10m/s is used,while a reference value of 100 m/s is used for the high-speed range.The speed output response indicates that themotor reached reference speed in amatter of seconds,as the delay time is between 8 and 10 s.The maximum amplitude of thrust achieved is less than 400N,demonstrating the controller’s capability to control a high-speed LIM with minimal thrust ripple.Due to the controlled speed range,the developed system is highly recommended for low-speed and high-speed and heavy-duty traction applications.

Compression behavior of 316L lattice structures produced by indirect additive manufacturing

As a new type of lightweight structure,metallic lattice structure has higher stiffness and strength to weight ratio.To freely obtain 316L lattice structures with designed cell structure and adjustable porosity,additive manufacturing combined with investment casting was conducted to fabricate the 316L lattice structures with Kelvin cell.The compression simulation of 316L lattice structures with different porosities was carried out by using the finite element method.The numerical simulation results were verified by compression experiment,and the simulated results were consistent with the compression tests.The compressive mechanical properties of 316L lattice structures are directly related to porosity and independent of strut diameters.The 316L lattice structures with Kelvin cell have a smooth stress-strain curve and obvious plastic platform,and the hump stress-strain curves are avoided.

Experimental Study on the Thermal Performances of a Tube-Type Indirect Evaporative Cooler

The so-called indirect evaporative cooling technology is widely used in air conditioning applications.The thermal characterization of tube-type indirect evaporative coolers,however,still presents challenges which need to be addressed to make this technology more reliable and easy to implement.This experimental study deals with the performances of a tube-type indirect evaporative cooler based on an aluminum tube with a 10 mm diameter.In particular,the required tests were carried out considering a range of dry-bulb temperatures between 16℃ and 18℃ and a temperature difference between the wet-bulb and dry-bulb temperature of 2℃∼4℃.The integrated convective heat transfer coefficient inside the tube in the drenching condition has been found to lie in the range between 36.10 and 437.4(W/(m^(2)⋅K)).

Indirect Carbon Reduction Path from the Perspective of Urban Climate Adaptation Planning

Since the 21^(st)century,the problem of global warming has been prominent,and the problem of climate change has attracted worldwide attention.All countries have issued urban climate adaptation planning policy documents to address the current climate problem.At the same time,the proposal of the“double carbon”vision allows us to focus on the carbon emission reduction of cities and buildings.In addition to the implementation of the direct carbon reduction approach in the whole life cycle of construction,the functional role of indirect carbon reduction cannot be underestimated.By analyzing the domestic and foreign urban climate adaptation planning policy documents,summarizing the indirect carbon reduction approaches,and analyzing the feasibility of the indirect carbon reduction and emission reduction methods from the perspective of urban climate adaptation planning,the indirect carbon reduction adaptation strategy is proposed,which provides a reference for the implementation of urban climate adaptation planning and the target completion of reaching the carbon neutralization and peak on time.

Spatial and temporal heterogeneity of the impact of per capita income on household indirect carbon emissions in western China

With China entering the stage of high-quality development,the issue of carbon emission has become a hot research topic.This paper analyzes the different temporal and spatial effects of per capita income on household indirect carbon emissions in western China.Based on the data of Chinese Family Panel Studies(CFPS)in 2016 and 2018 in the western China,this paper uses Regression analysis and Bayesian correlation analysis to study the relationship between per capita income and household indirect carbon emissions.The results showed that the indirect carbon emissions generated by the expenditure on food,housing and household equipment in the household consumption structure in the western China were relatively high.In 2016-2018,the per capita income and per capita household consumption indirect carbon emissions in the western China showed an increasing trend.There was a positive correlation between per capita income and indirect carbon emissions of per capita household consumption,and its correlation was gradually enhanced in time dimension.In the spatial dimension,the household indirect carbon emissions in Yunnan,Qinghai,Guangxi Zhuang and Ningxia in the western China were greatly affected by per capita income,while the household indirect carbon emissions in Guizhou was least affected by per capita income.Finally,the paper puts forward some problems that we should consider in the process of facing the per capita income growth and climate change:the collection of carbon tax,the optimization of household consumption structure,the research and development of low-carbon products,and the differentiated carbon reduction.

A Study on the Application of Indirect Speech Act Theory in CET-6 Listening

In recent years,the CET-6(College English Test,Band 6)has become an important standard to measure the English language ability of Chinese college students,and listening is a challenging task for many students.The application of indirect speech act theory in CET-6 listening is seldom studied.Therefore,it is crucial to study on it.Based on the two observation points of indirect speech act theory in CET-6 listening,this study analyzes the specific embodiment of conventional indirect speech acts and non-conventional indirect speech acts in listening,and discusses the effective teaching methods of CET-6 listening.

鸡产蛋下降综合征病毒间接免疫荧光检测方法的建立及应用

为建立检测鸡产蛋下降综合征病毒(EDSV)的间接免疫荧光方法,并对该检测方法的各个步骤进行优化,以鸡产蛋下降综合征病毒多抗血清和FITC标记的兔抗鸡IgG为组合,对一抗和二抗的最适工作浓度和孵育时间进行了优化,对IFA方法进行了敏感性、特异性和重复性试验。结果表明,检测接种EDSV的96孔细胞培养板时,多抗血清的最适工作浓度为1∶320,孵育时间为45 min;FITC标记的兔抗鸡IgG的最适工作浓度为1∶200,孵育时间为30 min;病毒敏感性试验表明,该方法可以检测到10-2 TCID 50/mL的病毒;多抗血清敏感度试验表明,当多抗血清稀释到1∶1280时仍可见较明显的特异性荧光;特异性试验表明,该方法只针对EDSV,而不与禽副流感病毒4型、鸡新城疫病毒等其他病原反应;批内重复性试验和批间重复性试验结果表明,该方法具有较好的重复性和可靠性。结果表明,建立的间接免疫荧光方法具有较高的灵敏度和较好的稳定性,可为我国禽源性生物材料EDSV的检测提供技术支持,有巨大的市场需求。

牛病毒性腹泻病毒E2蛋白的真核表达及间接ELISA抗体检测方法的建立

为建立检测牛病毒性腹泻病毒(Bovine viral diarrhea virus,BVDV)抗体的间接ELISA方法,利用昆虫细胞真核表达系统成功表达E2蛋白,将纯化后的E2蛋白作为包被抗原,用方阵滴定方法对影响ELISA的各个因素进行优化,并进行特异性、敏感性和重复性试验。结果表明,在昆虫细胞中表达了BVDV E2蛋白,Western blot证实目的蛋白可与BVDV阳性血清发生特异性反应。ELISA优化结果显示,E2蛋白最佳包被浓度为0.5μg/mL,最佳封闭液为1%明胶,最佳血清稀释度为1∶400,最佳血清作用方式为37℃作用30 min,酶标抗体的最佳作用方式为1∶2000稀释、37℃作用30 min,最佳底物作用时间为室温20 min,阳性临界值为OD 450≥0.423。与血清中和试验法进行比较,总符合率为97.8%,板内和板间重复性试验的变异系数均小于10%。该方法与牛常见病毒阳性血清均无交叉反应。说明建立的间接ELISA抗体检测方法特异性、敏感性和重复性良好,可用于大批量样本的临床检测和流行病学研究。

基于间接核查法的流量计云在线运行核查方法

在供热物理设备网中,除不同规模的流量计群外,还设有大量与流量有关的设备及部件。本文研究了利用供热系统的机理、被核查流量计的相关参数、供热物理设备网中设置的具有流量特性的设备或部件来判断被核查流量计工作状态的方法,并在此基础上提出了流量计的云在线运行核查技术流程,以快速判断在线应用的流量计的技术性能是否满足使用要求,解决供热企业核查人员及核查仪器设备不足的缺陷,有效提升智慧供热系统数据质量和提高控制系统的安全。

火山灰质材料的火山灰活性检测方法综述

本文将火山灰质材料的火山灰活性检测方法分为直接法和间接法两大类。其中,直接法包括石灰吸收值法,火山灰反应程度评定法和酸、碱溶出度法;而间接法包括物理性能法,水化反应放热量法和物理、化学特征参数法。为正确指导火山灰活性检测方法的应用,本文详细介绍并比较了各检测方法的原理和特点。笔者认为,直接法可直接测定出火山灰质材料与Ca(OH)2反应的程度,但其操作和分析过程相对复杂;间接法可通过测定火山灰质材料对体系物化性能的影响或材料自身的物理、化学特征参数来评价其火山灰活性。本文从材料科学的角度厘清了各检测方法的适用对象,认为应根据不同的火山灰质材料的特性选择与其相适应的火山灰活性检测方法。

雷电间接效应多重脉冲组电流产生装置的设计

针对雷电间接效应多重脉冲组电流模拟需求,完成了雷电间接效应多重脉冲组模拟源的设计,采用20个Crowbar电路支路,通过分时放电的方式实现1个脉冲串内多脉冲输出需求,每个支路可以实现最小间隔30 ms的重复频率放电,从而实现3个脉冲串的输出需求。对放电支路的参数进行了详细设计,分析了电容、波尾电路电感、波尾电路电阻参数变化对输出特性的影响。分析了采用并联大电容实现放电电容重复频率快速充电的可行性,完成了装置的初步结构设计并结合装置结构简要分析了电路模拟参数设置的合理性。该装置建成后,可为电子、电气设备等开展测试提供技术支持。

抗PCV4 Cap蛋白抗体间接ELISA检测方法的建立

为建立可应用于猪圆环病毒4型(PCV4)候选疫苗特异性抗体检测与评价方法,本研究应用PCV4 Cap蛋白作为抗原,以PCV4多克隆兔源抗体作为一抗,优化各反应的最佳条件并建立了针对PCV4 Cap蛋白抗体的间接ELISA方法。最佳条件为2μg/m L PCV4 Cap纯化蛋白,4℃包被过夜,5%脱脂乳封闭60 min,待检血清稀释比例为1∶800,反应条件为37℃、45 min,酶标抗体稀释比例为1∶5000,反应条件为37℃、60 min,底物显色时间为10 min,Cut of f值为0.157,灵敏度可达102400倍。成功建立的抗PCV4Cap蛋白抗体间接ELISA检测方法具有良好的敏感性、重复性和特异性。可为检测PCV4候选疫苗的特异性抗体水平提供一种精准、高效的方法。

体外丝线牵拉辅助两孔腹腔镜内环缝合在治疗内环口皱褶冗厚斜疝中的应用

目的探讨体外丝线牵拉辅助两孔腹腔镜内环缝扎治疗内环皱褶冗厚斜疝的安全性、可行性。方法2019年10月~2023年2月,322例斜疝患儿接受两孔法腹腔镜内环缝扎,其中186例(292侧)内环皱褶冗厚患儿采用体外丝线牵拉法辅助。在腹腔镜监视下,针持持针经内环口外下缘入腹膜,于腹膜后间隙走行至精索血管外侧缘出针;于精索血管外侧缘进针,体外轻轻牵拉线尾,腹腔镜下见进针点附近后腹膜间隙增大,缝针顺势在后腹膜间隙跨越精索血管表面。相同方法牵拉和展开折叠在输精管-髂外血管间隙的腹膜皱褶,增大后腹膜间隙,缝针继续在后腹膜间隙贴近髂血管表面跨越Doom三角区冗厚的腹膜组织。相同方法于腹膜外间隙跨越输精管表面。继续直视下缝合内环口内侧壁和上壁腹膜组织,于最初进针处出针和打结,闭合内环口。结果292侧体外丝线牵拉冗厚腹膜后,缝针能顺利跨越精索血管、Doom三角区以及输精管表面。80例单侧手术时间(18.5±3.2)min,106例双侧手术时间(32.6±5.3)min。均无术中并发症发生,均在术后6 h内出院。122例术后随访3~18个月(平均8.5月),未出现切口感染、医源性隐睾或睾丸萎缩等并发症,无复发疝、鞘膜积液。结论对于内环皱褶冗厚的儿童斜疝,体外丝线牵拉法可有效展开冗厚的后腹膜,降低两孔法腹腔镜内环口缝扎时缝针跨越精索血管、Doom三角区以及输精管表面的难度,具有安全性、可行性。

数字服务税收属性及中国税制构造进路

对数字服务税收属于直接税抑或间接税的属性判定,不仅关涉数字服务的产业发展及税基分配,也将深刻影响数字经济时代税制改革的方向与进路。部分国家着眼于间接税的制度厘定,采行开征数字服务税之类的单边“临时性”措施,会对数字消费产生抑制效应。基于对数字服务税收的直接税属性的判定,在既有所得税领域的税收协定框架下,联合国及经济合作与发展组织分别进行了税制改革方案设计。着眼于对数字服务征收直接税的路径选择,中国亟需实施双阶税制构造,将扩大预提税征税范围作为过渡措施,并作好重新配置税收管辖权的长期税制改革谋划。

OLIF手术间接减压失败的风险因素分析

目的探讨融合器高度和融合器位置等因素对OLIF手术间接减压效果的影响,同时分析OLIF术后间接减压失败的影响因素。方法回顾性分析该科2019年3月~2022年3月开展OLIF手术的103例LSS患者资料,手术节段为L2-3节段~L4-5节段;其中单节段手术63例,两节段手术26例,三节段手术14例。测量以下影像学指标:硬膜囊直径,椎管直径,硬膜囊横截面积(cross sectional area,CSA),椎管CSA,左右侧关节下直径,左右侧黄韧带厚度和黄韧带面积,椎间盘突出物的直径,椎间盘高度,节段性前凸角,椎间孔高度和椎间孔面积等。所有患者均随访6个月以上,观察间接减压失败的发生率,并分析其影响因素。结果103例患者均成功完成OLIF手术,与术前相比,患者术后6个月时的疼痛VAS评分均获得显著改善(P<0.001)。高度为14 mm的融合器(n=18)置入后,其硬膜囊直径、右侧黄韧带厚度和椎间盘突出物直径的收缩值等指标的改善程度,均显著大于高度为10 mm(n=9)和12 mm(n=76)的融合器(P<0.05)。融合器前置(n=48)可获得更好的节段性前凸矫正效果(P=0.041);而融合器后置(n=109)可获得更高的椎间盘后缘高度矫正效果(P=0.018),同时可获得更好的左、右侧关节下直径改善效果(P=0.005,P=0.019),右侧黄韧带厚度的减少程度也更显著(P=0.023)。多因素Logistic回归分析显示,术前硬膜囊CSA(OR=0.952)、融合器位置(OR=0.276),均是OLIF手术间接减压失败的独立影响因素。ROC曲线分析得出:(1)术前硬膜囊CSA的最佳截断值是47.3 mm^(2),敏感度为90.7%,特异度为82.9%,AUC=0.869;(2)术前融合器位置的最佳截断值是4.8,敏感度为61.8%,特异度为82.3%,AUC=0.757。结论OLIF手术是治疗LSS有效的间接减压术式,术中将融合器后置可获得更理想的减压效果;但对于术前硬膜囊CSA<47.3 mm^(2)的节段,可能不适合间接减压术式。融合器高度与OLIF手术的减压效果有关,但并不是独立影响因素。

地下进风系统对间接空冷塔性能的影响

削弱环境风对间接空冷塔散热器性能的不利影响,有助于其安全和经济运行。该文提出一种新型间接空冷塔地下进风系统,将空冷散热器整体布置在低于地表平面的地下空间内。建立配置地下进风系统的间接空冷塔数值计算模型,得到间接空冷塔的空气流场特性和热力特性。基于凝汽器和空冷散热器协同调节、相互制约的作用机制,采用机理模型和数值模拟相结合的方法建立排汽压力的计算模型,在此基础上计算地下进风系统的热经济性。结果表明,在4 m/s风速下,虽然迎风扇段空气流量减少14.5%,热负荷降低12.4%,但侧风扇段和背风扇段冷却空气量分别增加46.0%、8.0%,热负荷分别提升30.9%、3.2%。在高风速工况下,地下进风系统削弱环境风对排汽压力的影响,具有抵御自然大风的能力。某660 MW间接空冷机组,采用地下进风系统全年可节约标煤9554.3 t,节省燃料费1094.0万元。