H_(2)S^(+)在A^(2)A_(1)(v1=1,v2=8,v3=0)激发态的光解动力学

振动激发在分子和离子的光解动力学中有着重要的作用:开展特定振动激发态分子离子的光解离动力学实验研究存在很大挑战,尤其是实现合频振动激发离子的量子态选择的制备.本文利用时间切片离子速度成像技术研究了H_(2)S^(+)离子经A^(2)A_(1)(v1=1,v2=8,v3=0)激发态解离生成S^(+)(4S)和H_(2)的光解动力学.实验结合多光子电离和共振激发技术制备了振动激发的H_(2)S^(+),获得了离子在357.02~358.38nm范围内六个光解波长下产物S^(+)的速度影像.根据实验影像,获得了产物的总平动能谱和不同转动态的角分布各项异性参数特别指出地是在很窄的光解能量范围内,转动产物H_(2)(J=1)和H_(2)(J=3)的分支比出现多次反转,该现象与A^(2)A_(1)态单一振动模式激发的H2S+离子的光解动力学行为有明显不同.该研究表明,合频振动激发的H_(2)S^(+)离子光解动力学中可能存在振动模式之间的协同效应.

Quantum confinement of carriers in the type-I quantum wells structure

Quantum confinement is recognized to be an inherent property in low-dimensional structures.Traditionally,it is believed that the carriers trapped within the well cannot escape due to the discrete energy levels.However,our previous research has revealed efficient carrier escape in low-dimensional structures,contradicting this conventional understanding.In this study,we review the energy band structure of quantum wells along the growth direction considering it as a superposition of the bulk material dispersion and quantization energy dispersion resulting from the quantum confinement across the whole Brillouin zone.By accounting for all wave vectors,we obtain a certain distribution of carrier energy at each quantized energy level,giving rise to the energy subbands.These results enable carriers to escape from the well under the influence of an electric field.Additionally,we have compiled a comprehensive summary of various energy band scenarios in quantum well structures relevant to carrier transport.Such a new interpretation holds significant value in deepening our comprehension of low-dimensional energy bands,discovering new physical phenomena,and designing novel devices with superior performance.

Reanalysis of energy band structure in the type-II quantum wells

Band structure analysis holds significant importance for understanding the optoelectronic characteristics of semiconductor structures and exploring their potential applications in practice. For quantum well structures, the energy of carriers in the well splits into discrete energy levels due to the confinement of barriers in the growth direction. However, the discrete energy levels obtained at a fixed wave vector cannot accurately reflect the actual energy band structure. In this work, the band structure of the type-II quantum wells is reanalyzed. When the wave vectors of the entire Brillouin region(corresponding to the growth direction) are taken into account, the quantized energy levels of the carriers in the well are replaced by subbands with certain energy distributions. This new understanding of the energy bands of low-dimensional structures not only helps us to have a deeper cognition of the structure, but also may overturn many viewpoints in traditional band theories and serve as supplementary to the band theory of low-dimensional systems.

Relation of V/III ratio of AlN interlayer with the polarity of nitride

N-polar GaN film was obtained by using a high-temperature AlN buffer layer.It was found that the polarity could be inverted by a thin low-temperature AlN interlayer with the same V/III ratio as that of the high-temperature AlN layer.Continuing to increase the V/III ratio of the low-temperature AlN interlayer,the Ga-polarity of GaN film was inverted to N-polarity again but the crystal quality and surface roughness of GaN film greatly deteriorated.Finally,we analyzed the chemical environment of the AlN layer by x-ray photoelectron spectroscopy(XPS),which provides a new direction for the control of GaN polarity.

The Correlation between the Power Quality Indicators and Entropy Production Characteristics of Wind Power+Energy Storage Systems

Power quality improvements help guide and solve the problems of inefficient energy production and unstable power output in wind power systems.The purpose of this paper is mainly to explore the influence of different energy storage batteries on various power quality indicators by adding different energy storage devices to the simulated wind power system,and to explore the correlation between systementropy generation and various indicators,so as to provide a theoretical basis for directly improving power quality by reducing loss.A steady-state experiment was performed by replacing the wind wheel with an electric motor,and the output power qualities of the wind power systemwith andwithout energy storagewere compared and analyzed.Moreover,the improvement effect of different energy storage devices on various indicatorswas obtained.Then,based on the entropy theory,the loss of the internal components of the wind power system generator is simulated and explored by Ansys software.Through the analysis of power quality evaluation indicators,such as current harmonic distortion rate,frequency deviation rate,and voltage fluctuation,the correlation between entropy production and each evaluation indicator was explored to investigate effective methods to improve power quality by reducing entropy production.The results showed that the current harmonic distortion rate,voltage fluctuation,voltage deviation,and system entropy production are positively correlated in the tests and that the power factor is negatively correlated with system entropy production.In the frequency range,the frequency deviationwas not significantly correlated with the systementropy production.

Low-content Pt-triggered the optimized d-band center of Rh metallene for energy-saving hydrogen production coupled with hydrazine degradation

Utilizing the hydrazine-assisted water electrolysis for energy-efficient hydrogen production shows a promising application, which relies on the development and design of efficient bifunctional electrocatalysts. Herein, we reported a low-content Pt-doped Rh metallene(Pt-Rhene) for hydrazine-assisted water electrolysis towards energy-saving hydrogen(H_(2)) production, where the ultrathin metallene is constructed to provide enough favorable active sites for catalysis and improve atom utilization.Additionally, the synergistic effect between Rh and Pt can optimize the electronic structure of Rh for improving the intrinsic activity. Therefore, the required overpotential of Pt-Rhene is only 37 mV to reach a current density of-10 mA cm^(-2) in the hydrogen evolution reaction(HER), and the Pt-Rhene exhibits a required overpotential of only 11 mV to reach a current density of 10 mA cm^(-2) in the hydrazine oxidation reaction(HzOR). With the constructed HER-HzOR two-electrode system, the Pt-Rhene electrodes exhibit an extremely low voltage(0.06/0.19/0.28 V) to achieve current densities of 10/50/100 mA cm^(-2) for energy-saving H_(2) production, which greatly reduces the electrolysis energy consumption. Moreover,DFT calculations further demonstrate that the introduction of Pt modulates the electronic structure of Rh and optimizes the d-band center, thus enhancing the adsorption and desorption of reactant/intermediates in the electrocatalytic reaction.

Correlation Analysis of Wind Turbine Temperature Rise and Exergy Efficiency Based on Field-Path Coupling

To solve the problems of large losses and low productivity of permanent magnet synchronous generators used in wind power systems,the field-circuit coupling method is used to accurately solve the electromagnetic field and temperature field of the generator.The loss distribution of the motor is accurately obtained by considering the influence of external circuit characteristics on its internal physical field.By mapping the losses to the corresponding part of the three-dimensional finite element model of the motor,the temperature field is solved,and the global temperature distribution of the generator,considering the influence of end windings,is obtained.By changing the air gap length,permanent magnet thickness,and winding conductivity,the relationship between the loss,temperature rise,and exergy efficiency can be obtained.By optimizing the air gap length,permanent magnet thickness,and winding conductivity,the best configuration and material properties can improve the efficiency of the motor by up to 4%.

Teamwork and Physician Burnout: The Moderating Role of Perceived Organisational Support

Burnout is an important issue which has attracted the attention of physicians and health practitioners. Several studies have reported the negative effect of physician burnout and the adverse effect it has on the individual and health institutions. This study therefore examined the moderating effect of perceived organizational support on the relationship between teamwork and physician burnout in the Chinese context. Using a survey data consisting of a sample of physicians from hospitals within the Jiangsu Province of China, we estimated three models in a hierarchical framework and identified that in the presence of respondent’s demographic characteristics as control variables, perceived organizational support, play a very vital role in improving teamwork while reducing burnout among physicians.

土地整治项目建后管护PPP模式适用性分析

土地整治项目建后管护是衔接土地整治项目实施与整治后土地利用的重要环节,是促进土地整治项目持续发挥效益的关键要素。本研究从PPP模式参与土地整治项目建后管护的态势分析入手,构建建后管护模式适用性评价体系,选取典型案例进行模式细化与使用条件分析。主要研究结果如下:(1)土地整治项目建后管护的技术准入门槛相对较低,不断累积的技术经验和较为充足的社会资金等为引入PPP模式进行土地整治建后管护创造了条件;(2)在土地整治项目全生命周期下,PPP模式参与土地整治建后管护的适用性可以从政府、特殊目的实体(SPV)、村集体与土地利用等三方面进行综合评价;(3)典型案例分析表明,由于土地整治具有投资大、回收期长、权利主体保障要求高等特点,各模式下SPV都难以依靠收益分享实现财务平衡,亟待管理部门出台专项扶持政策。

High-resolution structure-from-motion models covering 160 km-long surface ruptures of the 2021 M_(W)7.4 Madoi earthquake in northern Qinghai-Tibetan Plateau

The May 222021 M_(W)7.4 Madoi,Qinghai,China earthquake presented a rare opportunity to apply the modern unmanned aerial vehicle(UAV)photography method in extreme altitude and weather conditions to image surface ruptures and near-field effects of earthquake-related surface deformations in the remote Tibet.High-resolution aerial photographs were acquired in the days immediately following the mainshock.The complex surface rupture patterns associated with this event were covered comprehensively at 3-6 cm resolution.This effort represents the first time that an earthquake rupture in the interior of the Qinghai-Tibetan Plateau has been fully and systematically captured by such high-resolution imagery,with an unprecedented level of detail,over its entire length.The dataset has proven valuable in documenting subtle and transient rupture features,such as the significant mole-tracks and opening fissures,which were ubiquitous coseismically but degraded during the subsequent summer storm season.Such high-quality imagery also helps to document with high fidelity the fractures of the surface rupture zone(supplements of this paper),the pattern related to how the faults ruptured to the ground surface,and the distribution of off-fault damage.In combination with other ground-based mapping efforts,the data will be analyzed in the following months to better understand the mechanics of earthquake rupture related to the fault zone rheology,rupture dynamics,and frictional properties along with the fault interface.

Characteristics of AlGaN/GaN high electron mobility transistors on metallic substrate

We have successfully prepared GaN based high electron mobility transistors(HEMTs)on metallic substrates transferred from silicon substrates by electroplating technique.GaN HEMTs on Cu substrates are demonstrated to basically have the same good electric characteristics as the chips on Si substrates.Furthermore,the better heat dissipation of HEMTs on Cu substrates compared to HEMTs on Si substrates is clearly observed by thermoreflectance imaging,showing the promising potential for very high-power and high-temperature operation.This work shows the outstanding ability of HEMT chips on Cu substrates for solving the self-heating effect with the advantages of process simplicity,high yield,and low production requirement.

A Fast-Fractional Flow Reserve Simulation Method in A Patient with Coronary Stenosis Based on Resistance Boundary Conditions

Fractional flow reserve(FFR)is the gold standard to identify individual stenosis causing myocardial ischemia in catheter laboratory.The purpose of this study is to present a fast simulation method to estimate FFR value of a coronary artery,which can evaluate the performance of vascular stenosis,based on resistance boundary conditions.A patient-specific 3-dimensional(3D)model of the left coronary system with intermediate diameter stenosis was reconstructed based on the CTA images.The resistance boundary conditions used to simulate the coronary microcirculation were computed based on anatomical reconstruction of coronary 3D model.This study was performed by coupling the 3D coronary tree model with the lumped parameter model(0D model).The flow rate and pressure of coronary tree were calculated in twenty minutes.In addition,the effect of inlet pressure and myocardial mass on FFRss values has been investigated.The results showed that the effect of myocardial mass was greater than the effect of inlet pressure on FFRss.This FFRss simulation method can quickly and accurately assess the influence of coronary stenosis in aid clinical diagnosis.

Global and Regional Trends and Projections of Infective Endocarditis-Associated Disease Burden and Attributable Risk Factors from 1990 to 2030

Objective To forecast the future burden and its attributable risk factors of infective endocarditis(IE).Methods We analyzed the disease burden of IE and its risk factors from 1990 to 2019 using the Global Burden of Disease 2019 database and projected the disease burden from 2020 to 2030 using a Bayesian age-period-cohort model.Results By 2030,the incidence of IE will increase uncontrollably on a global scale,with developed countries having the largest number of cases and developing countries experiencing the fastest growth.The affected population will be predominantly males,but the gender gap will narrow.The elderly in high-income countries will bear the greatest burden,with a gradual shift to middle-income countries.The incidence of IE in countries with middle/high-middle social-demographic indicators(SDI) will surpass that of high SDI countries.In China,the incidence rate and the number of IE will reach 18.07 per 100,000 and 451,596 in 2030,respectively.IEassociated deaths and heart failure will continue to impose a significant burden on society,the burden on women will increase and surpass that on men,and the elderly in high-SDI countries will bear the heaviest burden.High systolic blood pressure has become the primary risk factor for IE-related death.Conclusions This study provides comprehensive analyses of the disease burden and risk factors of IE worldwide over the next decade.The IE-associated incidence will increase in the future and the death and heart failure burden will not be appropriately controlled.Gender,age,regional,and country heterogeneity should be taken seriously to facilitate in making effective strategies for lowering the IE disease burden.

Association Analysis of Hyperlipidemia with the 28-Day All-Cause Mortality of COVID-19 in Hospitalized Patients

Objective This study aimed to determine the association of hyperlipidemia with clinical endpoints among hospitalized patients with COVID-19,especially those with pre-existing cardiovascular diseases(CVDs)and diabetes.Methods This multicenter retrospective cohort study included all patients who were hospitalized due to COVID-19 from 21 hospitals in Hubei province,China between December 31,2019 and April 21,2020.Patients who were aged<18 or≥85 years old,in pregnancy,with acute lethal organ injury(e.g.,acute myocardial infarction,severe acute pancreatitis,acute stroke),hypothyroidism,malignant diseases,severe malnutrition,and those with normal lipid profile under lipid-lowering medicines(e.g,statin,niacin,fenofibrate,gemfibrozil,and ezetimibe)were excluded.Propensity score matching(PSM)analysis at 1:1 ratio was performed to minimize baseline differences between patient groups of hyperlipidemia and non-hyperlipidemia.PSM analyses with the same strategies were further conducted for the parameters of hyperlipidemia in patients with increased triglyceride(TG),increased low・density lipoprotein cholesterol(LDL-C),and decreased high-density lipoprotein cholesterol(HDL-C).Mixed-effect Cox model analysis was performed to investigate the associations of the 28-days all-cause deaths of COVID-19 patients with hyperlipidemia and the abnormalities of lipid parameters.The results were verified in male,female patients,and in patients with pre-existing CVDs and type 2 diabetes.Results Of 1094S inpatients confirmed as COVID-19,there were 9822 inpatients included in the study,comprising 3513(35.8%)cases without hyperlipidemia and 6309(64.2%)cases with hyperlipidemia.Based on a mixed-effect Cox model after PSM at 1:1 ratio,hyperlipidemia was not associated with increased or decreased 28-day all-cause death[adjusted hazard ratio(HR),1.17(95%C/,0.95-1.44),P二0.151].Wb found that the parameters of hyperlipidemia were not associated with the risk of 28-day all-cause mortality[adjusted HR,1.23(95%CI,0.98-1.55),P=0.075 in TG increase group;0.78(95%CI,0.57-1.07),P=0.123 in LDL-C increase group;and 1.12(95%CI,0.9-1.39),P=0.299 in HDL-C decrease group,respectively].Hyperlipidemia was also not significantly associated with the increased mortality of COVID-19 in patients accompanied with CVDs or type 2 diabetes,and in both male and female cohorts.Conclusion Our study support that the imbalanced lipid profile is not significantly associated with the 28-day all-cause mortality of COVID-19 patients,even in those accompanied with CVDs or diabetes.Similar results were also obtained in subgroup analyses of abnormal lipid parameters.Therefore,hyperlipidemia might be not a major causative factor for poor outcome of COVID-19,which provides guidance for the intervention of inpatients during the epidemic of COVID-19.

Association Between Lipid Profiles and Left Ventricular Hypertrophy:New Evidence from a Retrospective Study

Objective To explore the association between lipid profiles and left ventricular hypertrophy in a Chinese general population.Methods We conducted a retrospective observational study to investigate the relationship between lipid markers[including triglycerides,total cholesterol,low-density lipoprotein cholesterol,high-density lipoprotein(HDL)cholesterol,non-HDL-cholesterol,apolipoprotein A-I,apolipoprotein B,lipoprotein[a],and composite lipid profiles]and left ventricular hypertrophy.A total of 309,400 participants of two populations(one from Beijing and another from nationwide)who underwent physical examinations at different health management centers between 2009 and 2018 in China were included in the cross-sectional study.7,475 participants who had multiple physical examinations and initially did not have left ventricular hypertrophy constituted a longitudinal cohort to analyze the association between lipid markers and the new-onset of left ventricular hypertrophy.Left ventricular hypertrophy was measured by echocardiography and defined as an end-diastolic thickness of the mterventricular septum or left ventricle posterior wall>11 mm.The Logistic regression model was used in the cross-sectional study.Cox model and Cox model with restricted cubic splines were used in the longitudinal cohort.Results In the cross-sectional study for participants in the highest tertile of each lipid marker compared to the respective lowest,triglycerides[odds ratio(OR):1.2S0,95%CI:1.060 to 1.474],HDL-cholesterol(OR:0.780,95%CI:0.662 to 0.918),and lipoprotein(a)(OR:1.311,95%C7:1.115 to 1.541)had an association with left ventricular hypertrophy.In the longitudinal cohort,for participants in the highest tertile of each lipid marker at the baseline compared to the respective lowest,triglycerides[hazard ratio(HR):3.277,95%C/:1.720 to 6.244],HDL-cholesterol(HR:0.516,95%C7:0.283 to 0.940),non-HDL-cholesterol(HR:2.309,95%C/:1.296 to 4.112),apolipoprotein B(HR:2.244,95%CI:1.251 to 4.032)showed an association with new-onset left ventricular hypertrophy.In the Cox model with forward stepwise selection,triglycerides were the only lipid markers entered into the final model.Conclusion Lipids levels,especially triglycerides,are associated with left ventricular hypertrophy.Controlling triglycerides level potentiate to be a strategy in harnessing cardiac remodeling but deserve to be furdier investigated.

Visualizing light-to-electricity conversion process in InGaN/GaN multi-quantum wells with a p-n junction

Absorption and carrier transport behavior plays an important role in the light-to-electricity conversion process, which is difficult to characterize. Here we develop a method to visualize such a conversion process in the InGaN/GaN multiquantum wells embedded in a p-n junction. Under non-resonant absorption conditions, a photocurrent was generated and the photoluminescence intensity decayed by more than 70% when the p-n junction out-circuit was switched from open to short. However, when the excitation photon energy decreased to the resonant absorption edge, the photocurrent dropped drastically and the photoluminescence under open and short circuit conditions showed similar intensity. These results indicate that the escaping of the photo-generated carriers from the quantum wells is closely related to the excitation photon energy.

Absorption Enhancement of Silicon Solar Cell in a Positive-Intrinsic-Negative Junction

Absorption coefficient is a physical parameter to describe electromagnetic energy absorption of materials, which is closely related to solar cells and photodetectors. We grow a series of positive-intrinsic-negative(PIN) structures on silicon wafer by a gas source molecule beam epitaxy system and the investigate the absorption coefficient through the photovoltaic processes in detail. It is found that the absorption coefficient is enhanced by one order and can be tuned greatly through the thickness of the intrinsic layer in the PIN structure, which is also demonstrated by the 730-nm-wavelength laser irradiation. These results cannot be explained by the traditional absorption theory.We speculate that there could be some uncovered mechanism in this system, which will inspire us to understand the absorption process further.

土地整治项目建后管护TOT模式设计

土地整治项目建后管护是衔接土地整治项目实施与整治后土地利用的重要环节,是促进土地整治项目持续发挥效益的关键要素。本研究从PPP模式设计的一般流程入手,通过物有所值(VFM)分析和成本收益分析,选取典型项目,围绕TOT模式对土地整治项目建后管护进行了设计。取得以下主要研究结果:(1)引入社会资本有利于鼓励创新和绩效导向机制,通过VFM分析,土地整治项目建后管护宜采用TOT模式;(2)通过C-D函数对社会资本最优规模进行估计,成本收益分析表明,在设置特许协议期为15年的条件下,社会资本不能实现收益;(3)为了有效发挥社会资本的作用,政府可以以工程结余资金作为管护基金,实施补贴或奖励机制,保障社会资本收益,提升管护积极性。

Characterization of the N-polar GaN film grown on C-plane sapphire and misoriented C-plane sapphire substrates by MOCVD

Gallium nitride(GaN) thin film of the nitrogen polarity(N-polar) was grown on C-plane sapphire and misoriented C-plane sapphire substrates respectively by metal-organic chemical vapor deposition(MOCVD). The misorientation angle is off-axis from C-plane toward M-plane of the substrates, and the angle is 2°and 4°respectively. The nitrogen polarity was confirmed by examining the images of the scanning electron microscope before and after the wet etching in potassium hydroxide(KOH) solution. The morphology was studied by the optical microscope and atomic force microscope. The crystalline quality was characterized by the x-ray diffraction. The lateral coherence length, the tilt angle, the vertical coherence length, and the vertical lattice-strain were acquired using the pseudo-Voigt function to fit the x-ray diffraction curves and then calculating with four empirical formulae. The lateral coherence length increases with the misorientation angle, because higher step density and shorter distance between adjacent steps can lead to larger lateral coherence length.The tilt angle increases with the misorientation angle, which means that the misoriented substrate can degrade the identity of crystal orientation of the N-polar GaN film. The vertical lattice-strain decreases with the misorientation angle. The vertical coherence length does not change a lot as the misorientation angle increases and this value of all samples is close to the nominal thickness of the N-polar GaN layer. This study helps to understand the influence of the misorientation angle of misoriented C-plane sapphire on the morphology, the crystalline quality, and the microstructure of N-polar GaN films.

A Steganography Model Data Protection Method Based on Scrambling Encryption

At present,the image steganography method based on CNN has achieved good results.The trained model and its parameters are of great value.Once leaked,the secret image will be exposed.To protect the security of steganographic network model parameters in the transmission process,an idea based on network model parameter scrambling is proposed in this paper.Firstly,the sender trains the steganography network and extraction network,encrypts the extraction network parameters with the key shared by the sender and the receiver,then sends the extraction network and parameters to the receiver through the public channel,and the receiver recovers them with the key after receiving,to achieve more secure secret communication.In this way,even if the network parameters are intercepted by a third party in the transmission process,the interceptor cannot extract the real secret information.In this paper,the classical Joseph algorithm is used as the scrambling algorithm to scramble the extracted network model parameters of the StegoPNet steganography network.The experimental results show that when the scrambled parameters are used for secret image extraction,a meaningless image independent of the secret image is extracted,it shows that this method can well protect the security of steganography network model.At the same time,this method also has good scalability,and can use a variety of different scrambling algorithms to scramble the parameters.