嵌入铂单原子的苯并咪唑基共价有机框架实现高效可见光析氢

氢气(H_(2))是一种清洁的无碳燃料,具有很高的能量密度,是化石能源的潜在替代品之一.半导体光催化水分解反应可将取之不竭的太阳能转化为氢气中的化学能,从而提供一条有前途的、经济和环境友好的产氢路线.光催化析氢反应(HER)涉及光捕集、激发、电荷分离和传输,以及表面质子还原过程.光激发态通常在几皮秒内发生,通过辐射或非辐射复合弛豫返回到基态,然而,光生电子迁移到表面并触发两电子的质子还原是一个慢过程,时间通常在几毫秒或以上.整个过程中转换效率因光生电子极易复合而大大降低.因此,如何延长光生电子寿命,促进电子及时传递到表面析氢位点,提高催化位点的析氢速率,是设计水分解高效光催化剂的关键,也是该领域的难题.有机半导体催化剂可以从地球丰度高的轻元素制备,具有成本低、毒性小和结构多样等特点.其中一个典型代表是共价有机框架(COFs),其具有大的比表面积及丰富可调的骨架组成和孔道结构,在分子水平上的可设计性具有独特优势.苯并咪唑化合物具有较大极性和灵活可调的π共轭结构,被广泛用作光电器件的共轭辅助分子.以苯并咪唑基单体直接合成的COF种类罕见,且未见相关COF用于光催化反应的报道.本文通过选用不对称的苯并咪唑单体(2-(4-氨基苯基)-5-氨基苯并咪唑)与三醛基间苯三酚直接通过席夫碱化学反应缩合,制备了苯并咪唑基COF.该COF材料有效促进了光吸收和电荷分离/传递,以及高活性Pt单原子析氢位点的形成,在可见光驱动的析氢反应中表现出较好的析氢速率和转换频率.采用微波辅助的溶剂热策略快速合成了苯并咪唑基COF(PABZ-Tp),通过X射线衍射、傅立叶变换红外吸收光谱、13C固态核磁共振等研究其结构.光学和光电化学表征结果表明,PABZ-Tp在可见光范围.内展现出较好的光吸收,具有较低的激子解离能(17.8 meV),有效促进了长寿命自由光电子的形成.骨架中带负电荷的苯并咪唑基团不但是Pt单原子形成和稳定的主要因素,还有助于构建良好的电子迁移通道,从而有效促进了光生电子快速传递到表面Pt单原子位点,使得该催化剂在可见光驱动的析氢反应中表现出较高的催化效率,析氢速率高达115 mmol g^(-1)h^(-1),转换频率为4475.1 h^(-1).理论计算结合瞬态吸收光谱等实验结果表明,苯并咪唑COF框架是产生高活性的关键,对于光吸收、电荷分离传递以及高效析氢位点的构筑均起了重要作用.综上,本文构筑了一种高效的COF基有机光催化剂用于可见光析氢过程.展示了使用不对称咪唑基单体构筑功能化COF材料的广阔前景.

Direct measurement of an energy-dependent single-event-upset cross-section with time-of-flight method at CSNS

To predict the soft error rate for applications, it is essential to study the energy dependence of the single-event-upset(SEU) cross-section. In this work, we present a direct measurement of the SEU cross-section with the Back-n white neutron source at the China Spallation Neutron Source. The measured cross section is consistent with the soft error data from the manufacturer and the result suggests that the threshold energy of the SEU is about 0.5 Me V, which confirms the statement in Iwashita’s report that the threshold energy for neutron soft error is much below that of the(n, α) cross-section of silicon.In addition, an index of the effective neutron energy is suggested to characterize the similarity between a spallation neutron beam and the standard atmospheric neutron environment.

Large-areaβ-Ga_(2)O_(3) Schottky barrier diode and its application in DC-DC converters

We demonstrate superb large-area verticalβ-Ga_(2)O_(3)SBDs with a Schottky contact area of 1×1 mm^(2)and obtain a high-efficiency DC-DC converter based on the device.Theβ-Ga_(2)O_(3)SBD can obtain a forward current of 8 A with a forward volt-age of 5 V,and has a reverse breakdown voltage of 612 V.The forward turn-on voltage(VF)and the on-resistance(Ron)are 1.17 V and 0.46Ω,respectively.The conversion efficiency of theβ-Ga_(2)O_(3)SBD-based DC-DC converter is 95.81%.This work indicates the great potential of Ga_(2)O_(3)SBDs and relevant circuits in power electronic applications.

Reducing dielectric confinement effect in ionic covalent organic nanosheets to promote the visible-light-driven hydrogen evolution

Ultra-thin two-dimensional(2D)organic semiconductors are promising candidates for photocatalysts because of the short charge diffusion pathway and favorable exposure of active sites plus the versatile architecture.Nonetheless,the inherent dielectric confinement of 2D materials will induce a strong exciton effect hampering the charge separation.Herein,we demonstrated an effective way to reduce the dielectric confinement effect of 2D ionic covalent organic nanosheets(iCONs)by tailoring the functional group via molecular engineering.Three ultra-thin CONs with different functional groups and the same ionic moieties were synthesized through Schiff base condensation between ionic amino monomer triaminoguanidinium chloride(TG)and aldehyde linkers.The integration of the hydroxyl group was found to significantly increase the dielectric constant by enhancing the polarizability of ionic moieties,and thus reduced the dielectric confinement and the corresponding exciton binding energy(E_(b)).The champion hydroxyl-functional iCON exhibited promoted exciton dissociation and in turn a high photocatalytic hydrogen production rate under visible-light irradiation.This work provided insights into the rationalization of the dielectric confinement effect of low-dimensional photocatalysts.

Spatial differentiation and dynamic mechanism of micro-geomorphology based on acoustic spectrum data of the Huanghe(Yellow)River Delta

Submarine micro-geomorphology is a geo-morphological type occurring in shallow and surface areas of seabed.The combined relationships and distribution of the micro-geomorphology indirectly reflect coupling relationships among the sediment deposition,dynamic environment,and geomorphologic evolution.Spatial differentiation and dynamic changes in micro-geomorphology were studied based on acoustic data interpretation from a wide range(3200 km^(2))of the Huanghe(Yellow)River delta(HRD).The combination of the sub-bottom profiler and the side-scan sonar methods allowed for the identification of submarine shallow micro-geomorphologic types,as well as their scale and spatial distributions.There were seven typical micro-geomorphologic features in the shallow and surface areas of the HRD,including buried ancient channels,stratigraphic disturbances,scour troughs,sand waves,pits,erosional remnants,and sand spots.The coupling and superposition of the sediment,sediment characteristics,seabed scouring and silting,and hydrodynamic conditions of the Huanghe River had combined effects on the patterns of micro-geomorphologic types,characteristics,and ranges.From the perspective of acoustic profile interpretations,the scale,range,and spatial locations of the microgeomorphology in the HRD revealed seasonal variation characteristics,and the spatial distributions displayed significant regional differentiation characteristics.In addition,strong stratigraphic disturbances and areas with densely distributed buried ancient channels reflected the activity and instability of the submarine shallow strata.Through the interpretation of the sub-bottom profile detection data,the diversion processes of the flow paths in the lower reaches of the Huanghe River were obtained for a certain historical period in the coastal waters of the HRD.This study further clarified the relationships between the micro-geomorphologic features and spatial combinations,which is important for research on micro-geomorphologic features and their dynamic mechanisms.

Solid-state Al-air battery with an ethanol gel electrolyte

Hydrogel electrolyte is especially suitable for solid-state Al-air batteries targeted for various portable applications, which may, however, lead to continuous Al corrosion during battery standby. To tackle this issue, an ethanol gel electrolyte is developed for Al-air battery for the first time in this work, by using KOH as solute and polyethylene oxide as gelling agent. The ethanol gel is found to effectively inhibit Al corrosion compared with the water gel counterpart, leading to stable Al storage. When assembled into an Al-air battery, the ethanol gel electrolyte achieves a much improved discharge lifetime and specific capacity, which are 5.3 and 4.1 times of the water gel electrolyte at 0.1 mA cm^(-2), respectively.By studying the gel properties, it is found that a lower ethanol purity can improve the battery power output, but at the price of decreased discharge efficiency. On the contrary, a higher polymer concentration will decrease the power output, but can bring extra benefit to the discharge efficiency. As for the gel thickness, a moderate value of 1 mm is preferred to balance the power output and energy efficiency. Finally, to cater the increasing market of flexible electronics, a flexible Al-air battery is developed by impregnating the ethanol gel into a paper substrate, which can function normally even under serious deformation or damage.

Paper-based aqueous Al ion battery with water-in-salt electrolyte

Low-cost,flexible and safe battery technology is the key to the widespread usage of wearable electronics,among which the aqueous Al ion battery with water-in-salt electrolyte is a promising candidate.In this work,a flexible aqueous Al ion battery is developed using cellulose paper as substrate.The water-in-salt electrolyte is stored inside the paper,while the electrodes are either printed or attached on the paper surface,leading to a lightweight and thin-film battery prototype.Currently,this battery can tolerate a charge and discharge rate as high as 4 A g^(-1) without losing its storage capacity.The charge voltage is around 2.2 V,while the discharge plateau of 1.6–1.8 V is among the highest in reported aqueous Al ion batteries,together with a high discharge specific capacity of~140 mAh g^(-1).However,due to the water electrolysis side reaction,the faradaic efficiency can only reach 85%with a cycle life of 250 due to the dry out of electrolyte.Benefited from using flexible materials and aqueous electrolyte,this paper-based Al ion battery can tolerate various deformations such as bending,rolling and even puncturing without losing its performance.When two single cells are connected in series,the battery pack can provide a charge voltage of 4.3 V and a discharge plateau as high as 3–3.6 V,which are very close to commercial Li ion batteries.Such a cheap,flexible and safe battery technology may be widely applied in low-cost and large-quantity applications,such as RFID tags,smart packages and wearable biosensors in the future.

电化学阳极氧化法制备类纳米管结构WO_3光阳极用于光电催化全分解水(英文)

近年来,随着能源和环境问题日益凸显,新型可再生能源的开发利用意义重大.其中开发高效的光阳极材料用于光电催化全分解水引起了广泛的研究兴趣.纳米WO_3由于其禁带宽度适中,被证明是一种效果良好的光催化分解水产氧的催化剂,但无法直接用于催化析氢.若将其作为光阳极材料,在施加较低偏压下可用于高效光电催化全分解水.纳米WO_3电极的众多制备方法中,电化学氧化法因其方法简单,高效,制备成本低而具有重要的应用价值.然而,通常情况下电化学氧化法得到的纳米WO_3薄膜多为无规则形貌或多孔膜.本文发展了一种简单的阳极氧化法,通过优化调变其制备过程中的氧化时间,氧化电压,电解质离子浓度以及焙烧温度,确定了最佳制备条件(1 h,40 V,0.15 mol/L NH4F,400℃)时样品的光电催化全分解水活性最高,其光电催化析氢和析氧的速率分别达到了3.93和1.96μmol/cm^2/h,且量子效率达5.23%的,此NAs-WO_3/W薄膜的光电催化活性和稳定性远超商业WO_3/W薄膜.场发射扫描电镜结果显示,所制样品是一种新型的形貌规整的类纳米管阵列状WO_3薄膜.并进一步通过X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、X射线光电子能谱(XPS)、紫外可见光谱、光电转换效率、光电流测试、和交流阻抗等手段研究了其晶体结构、表面化学组成、光学及光电化学性质.同时通过实验与计算获得了NAs-WO_3/W薄膜在420 nm单色光照下的表面空穴分离率,并与商业WO_3制备得到的WO_3/W薄膜进行了相关对比.XRD,HRTEM和XPS结果表明,所制NAs-WO_3/W薄膜是由暴露(020)和(202)晶面的单斜晶相WO_3构成.交流阻抗测试表明,NAs-WO_3/W的交流阻抗值要远小于商业WO_3/W,说明其光生载流子分离效果要比商业化的WO_3/W高;且NAs-WO_3/W薄膜的表面空穴分离率是商业WO_3/W薄膜的三倍.由此可见NAs-WO_3/W具有优异的光电催化性能(高光电转换效率和空穴分离效率),能有效应用于可见光全分解水反应,这主要归因于其类纳米管阵列的特殊一维结构、高结晶度的单斜态WO_3及WO_3与金属W片之间的强相互作用.本文为高效光电转换材料的制备提供了新的技术与途径.

Pyrolyzing soft template-containing poly(ionic liquid)into hierarchical N-doped porous carbon for electroreduction of carbon dioxide

Heteroatom-doped carbon materials have demonstrated great potential in the electrochemical reduction reaction of CO_(2)(CO_(2)RR)due to their versatile structure and function.However,rational structure control remains one challenge.In this work,we reported a unique carbon precursor of soft template-containing porous poly(ionic liquid)(PIL)that was directly synthesized via free-radical self-polymerization of ionic liquid monomer in a soft template route.Variation of the carbonization temperature in a direct pyrolysis process without any additive yielded a series of carbon materials with facile adjustable textural properties and N species.Significantly,the integration of soft-template in the PIL precursor led to the formation of hierarchical porous carbon material with a higher surface area and larger pore size than that from the template-free precursor.In CO_(2)RR to CO,the champion catalyst gave a Faraday efficiency of 83.0%and a current density of 1.79 mA·cm^(-2)at-0.9 V vs.reversible hydrogen electrode(vs.RHE).The abundant graphite N species and hierarchical pore structure,especially the unique hierarchical small-/ultramicropores were revealed to enable better CO_(2)RR performance.

Genetic Fingerprint Concerned with Lymphatic Metastasis of Human Lung Squamous Cancer

背景与目的筛选肺鳞癌患者淋巴转移差异表达基因群。方法原发癌组织及区域淋巴结取自10例接受完全性肺癌切除手术的肺鳞癌患者。根据组织来源将标本分为三组:不伴淋巴转移的肺鳞癌组织(TxN-,n=5)、伴有淋巴转移的肺鳞癌组织(TxN+,n=5)及相应转移淋巴结中的肺鳞癌细胞(N+,n=5)。对各组进行激光显微切割以获得纯净癌细胞,T7RNA线性扩增获取足够量的RNA,实验通道和参照通道分别标记以后与含6000个已知人类基因或表达序列标签的cDNA基因芯片杂交,扫描荧光信号以后进行数据分析。结果共有37个基因可将TxN+组与TxN-组区分开,其中在TxN+组高表达的基因有8个,主要涉及蛋白合成、信号传导、伴侣蛋白和酶等。有29个基因在TxN-组高表达,这些基因主要编码细胞周期调节子、转导子、信号传导蛋白以及细胞凋亡调节蛋白。比较N+组与TxN+组却没有发现具有显著性的差异表达基因。结论肺鳞癌的淋巴转移表型的获得可能是早期事件。这些差异基因的发现有助于阐明肺鳞癌淋巴转移的分子机制和寻找新的治疗靶点。

Fully Printed High‑Performance n‑Type Metal Oxide Thin‑Film Transistors Utilizing Coffee‑Ring Effect

Metal oxide thin-films transistors(TFTs)produced from solution-based printing techniques can lead to large-area electronics with low cost.However,the performance of current printed devices is inferior to those from vacuum-based methods due to poor film uniformity induced by the“coffeering”effect.Here,we report a novel approach to print highperformance indium tin oxide(ITO)-based TFTs and logic inverters by taking advantage of such notorious effect.ITO has high electrical conductivity and is generally used as an electrode material.However,by reducing the film thickness down to nanometers scale,the carrier concentration of ITO can be effectively reduced to enable new applications as active channels in transistors.The ultrathin(~10-nm-thick)ITO film in the center of the coffee-ring worked as semiconducting channels,while the thick ITO ridges(>18-nm-thick)served as the contact electrodes.The fully inkjet-printed ITO TFTs exhibited a high saturation mobility of 34.9 cm2 V^(−1) s^(−1) and a low subthreshold swing of 105 mV dec^(−1).In addition,the devices exhibited excellent electrical stability under positive bias illumination stress(PBIS,ΔV_(th)=0.31 V)and negative bias illuminaiton stress(NBIS,ΔV_(th)=−0.29 V)after 10,000 s voltage bias tests.More remarkably,fully printed n-type metal–oxide–semiconductor(NMOS)inverter based on ITO TFTs exhibited an extremely high gain of 181 at a low-supply voltage of 3 V,promising for advanced electronics applications.

Effects of Bag Type on Fruit Quality of Red Massh Grapefruit

[Objectives]The effects of bag types on the appearance and internal quality of red Massh grapefruit were studied.[Methods]Outer-yellow inner-black double-layer pomelo special paper bags,white single-layer paper bags,yellow plastic film bags,and red plastic film bags were used to cover the fruit of red Massh grapefruit.With the fruit free of bagging as a control,the effects of fruit bags with different materials were compared.[Results]The four kinds of fruit bag treatments effectively reduced pests and diseases,and increased the good fruit rate,and the effects of paper bag treatments were better than those of film bags.The outer-yellow inner-black double-layer pomelo special paper bags had good air permeability and were easy to operate.The bagged fruit had a smooth and beautiful surface and showed a unique uniform pink color after removing the bags.The fruit had moderate sour and sweet flavor and good overall benefits.It is worthy of popularization and application.[Conclusions]Fruit bagging has good economic benefits,and it is recommended to use the outer-yellow inner-black double-layer pomelo special paper bags.

Modeling and Simulation of Automatic Berthing based on Bow and Stern Thruster Assist for Unmanned Surface Vehicle

In order to solve the technical problems of autonomous berthing of the Unmanned Surface Vehicle(USV),this research has met the requirements of maneuverability berthing under different conditions by effectively using the bow and stern thrusters,which is a technological breakthrough in actual production and life.Based on the MMG model,the maneuverability mathematical model of the USV with bow and stern thruster was established.And the motion simulation of USV maneuvering was carried out through the numerical simulation calculation.Then the berthing plan was designed based on the maneuverability analysis of the USV low-speed motion,and the simulation of automatic berthing for USV was carried out.The research results of this paper can be of certain practical significance for the USV based on the support of the bow and stern thruster in the berthing.At the same time,it also provides a certain theoretical reference for the handling of the USV automatic berthing.

Factors Influencing Home Ranges of the Qinghai Toad-headed Lizard(Phrynocephalus vlangalii)on the Dangjin Mountain,Gansu

Home range is an important ecological parameter reflecting the suita bility of animal habitats.To study the size and factors influencing the home ranges of the Qinghai toad-headed lizard(Phr ynocephalus vlangalii)in different habitats,from July to September 2020,we radio-tagged and tracked 15 individuals in each of sites distributed at high(3600 m)and low(2600 m)altitudes on the Dangjin Mountain,Gansu Province,northwest China.We calculated home range size using the 100%minimum convex polygon method,and analyzed the influence of inherent lizard characteristics and external environmental factors.Our results revealed that for both high-and lowaltitude lizard populations,the sizes of home ranges were positively correlated with lizard body mass.Moreover,after eliminating the effect of body mass as a covariable,we established that the home ranges of high-altitude lizards(5255.1±1103.8 m^(2))were larger than those of the low-altitude lizards(2208.1±348.7 m^(2)).Lizards in the high-altitude population were also characterized by longer daily suitable activity times and spent significantly more time in full sunlight than those in the low-altitude population.Furthermore,the food resources for lizards in low-altitude habitats were more abundant than those in high-altitude habitats In conclusion,we established that P.vlangalii lizards inhabiting high-altitude sites had larger home ranges than conspecific lizards distributed at a lower altitude,which was associated not only with endogenous factors,such as body mass,but also with habitat-related environmental factors,such as the quality of thermal resources and availability of food.

Primary balloon angioplasty for chronic occlusion of intracranial internal carotid artery: A case report

Chronic occlusion of large intracranial arteries is the main cause of ischemic stroke in China.Patients with symptomatic intracranial artery occlusion and hemodynamic impairment are at high risk of recurrent stroke.Chronic occlusion of the intracranial segment of the internal carotid artery is a common type of intracranial artery occlusion.Medical management is regarded as the standard treatment for this disease.With the development of endovascular treatment,some patients with chronic cerebral artery occlusion have achieved satisfactory results with endovascular therapy.We reported a patient with symptomatic chronic occlusion of the ophthalmic segment of the internal carotid artery.Simple balloon angioplasty was performed,and the occluded ophthalmic segment of the internal carotid artery was successfully recanalized without perioperative complications.At 4 months followup,the internal carotid artery remained patent and perfusion of the right cerebral hemisphere improved dramatically.In addition,we briefly reviewed the relevant literature.

Non-radical activation of persulfate with Bi_(2)O_(3)/BiO_(1.3)I_(0.4)for efficient degradation of propranolol under visible light

Non-radical activation of persulfate(PS)by photocatalysts is an effective approach for removing organic pollutants from aqueous environments.In this study,a novel Bi_(2)O_(3)/BiO_(1.3)I_(0.4)heterojunction was synthesized using a facile solvothermal approach and used for the first time for non-radical activation of PS to degrade propranolol(PRO)in the presence of visible light.The findings found that the degradation rate of PRO in the Bi_(2)O_(3)/BiO_(1.3)I_(0.4)/PS system was significantly increased from 19%to more than 90%within 90 min compared to the Bi_(2)O_(3)/BiO_(1.3)I_(0.4)system.This indicated that the composite system exerted an excellent synergistic effect between the photocatalyst and the persulfate-based oxygenation.Quenching tests and electron paramagnetic resonance demonstrated that the non-radical pathway with singlet oxygen as the active species played a major role in the photocatalytic process.The existence of photo-generated holes during the reaction could also be directly involved in the oxidation of pollutants.Meanwhile,a possible PRO degradation pathway was also proposed.Furthermore,the impacts of pH,humic acid and common anions on the PRO degradation by the Bi_(2)O_(3)/BiO_(1.3)I_(0.4)/PS were explored,and the system’s stability and reusability were also studied.This study exhibits a highly productive catalyst for PS activation via a non-radical pathway and provides a new idea for the degradation of PRO.

Graphitic carbon nitride-based photocatalysts in the applications of environmental catalysis

Semiconductor photocatalytic technology has shown great prospects in converting solar energy into chemical energy to mitigate energy crisis and solve environmental pollution problems.The key issue is the development of high-efficiency photocatalysts.Various strategies in the state-of-the-art advancements,such as heterostructure construction,heteroatom doping,metal/single atom loading,and defect engineering,have been presented for the graphitic carbon nitride(g-C3N4)-based nanocomposite catalysts to design their surface chemical environments and internal electronic structures to make them more suitable for different photocatalytic applications.In this review,nanoarchitecture design,synthesis methods,photochemical properties,potential photocatalytic applications,and related reaction mechanisms of the modified high-efficiency carbon nitride-based photocatalysts were briefly summarized.The superior photocatalytic performance was identified to be associated with the enhanced visible-light response,fast photoinduced electron-hole separation,efficient charge migration,and increased unsaturated active sites.Moreover,the further advance of the visible-light harvesting and solar-to-energy conversions are proposed.

UV light-induced oxygen doping in graphitic carbon nitride with suppressed deep trapping for enhancement in CO_(2) photoreduction activity

While photoreduction of CO_(2) to CH 4 is an effective means of producing value-added fuels,common pho-tocatalysts have poor activity and low selectivity in photocatalytic CO_(2)-reduction processes.Even though creating defects is an effective photocatalyst fabrication route to improve photocatalytic activity,there are some challenges with the facile photocatalyst synthesis method.In this work,an O element is in-troduced into a graphitic carbon nitride(CN)skeleton through a precursory ultraviolet light irradiation pretreatment to increase the visible light absorption and enhance the carrier density of this modified non-metal CN photocatalyst;the charge transfer dynamics thereof are also studied through electrochem-ical tests,photoluminescence spectroscopy,and nanosecond transient absorption.We verify that the op-timized sample exhibits lower charge recombination and a suppressed 84 ns electron-trapping lifetime,compared to the 103 ns electron-trapping lifetime of the CN counterpart,and thereby contributes to ro-bust detrapping and a fast transfer of active electrons.Through density functional theory calculations,we find that the improved light absorption and increased electron density are ascribed to O-element doping,which enhances the CO_(2) adsorption energy and improves the CO_(2)-to-CH 4 photoreduction activity;it be-comes 17 times higher than that of the bare CN,and the selectivity is 3.8 times higher than that of CN.Moreover,the optimized sample demonstrates excellent cyclic stability in a 24-hour cycle test.

硅掺杂MOCVD氧化镓中的非故意掺杂效应:浅施主态

本文利用MOCVD外延生长了不同载流子浓度的高质量β-Ga_(2)O_(3)薄膜并通过变温霍尔测量和二次离子质谱(SIMS)分析研究了薄膜中的浅施主态.通过拟合提取出薄膜中存在的两个电离能分别为~36和~140 meV的施主能级.进一步研究发现非故意掺杂(UID)效应对这两个能级都有影响:第一个施主能级不仅来源于硅掺杂也来源于非故意碳掺杂取代Ga位,第二个施主能级主要来源于与非故意掺杂氢相关的双电荷缺陷.通过分析生长条件与施主态之间的关系结合密度泛函理论计算我们发现在生长过程中降低氧分压可能有助于降低UID效应.该工作为硅掺杂MOCVDβ-Ga_(2)O_(3)薄膜载流子浓度的精确控制奠定了基础.

Altitudinal variation in life-history features of a Qinghai-Tibetan Plateau lizard

Environmental changes along an altitudinal gradient can facilitate the differentiation of life-history features in ectothermic species,but little attention has been devoted to the reciprocal influence of altitude and alpine slope directionality on life-history variation.According to life-history theory,increased environmental stress causes a change in reproductive allocation from number to quality of offspring,as well as a stronger trade-off between size and number of offspring.To clarify the influence of environmental pressures on the life-history features of the Qinghai toad-headed lizard Phrynocephalus vlangalii along an altitudinal cline,we surveyed late pregnant females from 3 populations of low(2,600 m),middle(3,400 m),and high(3,600 m)elevations in the Dangjin Mountain of Gansu,China from July to October 2019,and compared their inter-population differences in maternal body size,reproductive characteristics,offspring growth,and locomotor performance.Because of lower temperatures,higher humidity,and lower light intensity caused by slope aspect and altitude,the middle-altitude region experienced stronger environmental stress than the high-and low-altitude regions.Our results showed that females were larger at middle-and high-altitude sites and smaller at the low-altitude site,following Bergmann’s rule.We also found that females from low-altitude population gave birth earlier than those from the middle and high altitudes.Our results showed a shift in the offspring size-number trade-off of P.vlangalii in response to colder and harsher environments,with lizards from the alpine steppe(i.e.the middle-and high-altitude habitats)producing fewer but larger offspring than those from the warm steppe(i.e.the low-altitude habitat).Low-altitude juveniles grew faster than high-altitude ones,but at the same rates as middle-altitude juveniles.This result demonstrates that the growth of P.vlangalii was associated with temperature and light intensity.Our findings contribute to enhancing our understanding of the altitudinal variation in life-history features of plateau ectotherms and their phenotypic plasticity or local adaptation.