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.

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。

Nanotube array-like WO_3/W photoanode fabricated by electrochemical anodization for photoelectrocatalytic overall water splitting

Photoactive WO3is attractive as a photocatalyst for green energy evolution through water splitting.In the present work,an electrochemical anodic oxidation method was used to fabricate a photo‐responsive nanotube array‐like WO3/W(NA‐WO3/W)photoanode from W foil as a precursor.Compared with a reference commercial WO3/W electrode,the NA‐WO3/W photoanode exhibited enhanced and stable photoelectrocatalytic(PEC)activity for visible‐light‐driven water splitting with a typical H2/O2stoichiometric ratio of2:1and quantum efficiency of approximately5.23%under visible‐light irradiation from a light‐emitting diode(λ=420nm,15mW/cm2).The greatly enhanced PEC performance of the NA‐WO3/Wphotoanode was attributed to its fast electron–hole separation rate,which resulted from the one‐dimensional nanotube array‐like structure,high crystallinity of monoclinic WO3,and strong interaction between WO3and W foil.This work paves the way to a facile route to prepare highly active photoelectrodes for solar light transfer to chemical energy.

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.

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.

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.

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.

Simulation and forecasting of fishery weather based on statistical machine learning

As the new generation of artificial intelligence(AI)continues to evolve,weather big data and statistical machine learning(SML)technologies complement each other and are deeply integrated to significantly improve the processing and forecasting accuracy of fishery weather.Accurate fishery weather services play a crucial role in fishery production,serving as a great safeguard for economic benefits and personal safety,enabling fishermen to carry out fishery production better,and contributing to the sustainable development of the fishery industry.The objective of this paper is to offer an understanding of the present state of research and development in SML technology for simulating and forecasting fishery weather.Specifically,we analyze the current state of research and technical features of SML in weather and summarize the applications of SML in simulation and forecasting of fishery weather,which mainly include three aspects:fishery weather scenario generation,fishery weather forecasting,and fishery extreme weather warning.We also illustrate the main technical means and principles of SML technology.Finally,we summarize the most advanced SML fields and provide an outlook on their application value in the field of fishery weather.

Crop pest image recognition based on the improved ViT method Author links open overlay panel

The crop pests and diseases in agriculture is one of the most important reason for the reduction of bulk grain and oil crops and the decline of fruit and vegetable crop quality,which threaten macroeconomic stability and sustainable development.However,the recognition method based on manual and instruments has been unable to meet the needs of scientific research and production due to its strong subjectivity and low efficiency.The recognition method based on pattern recognition and deep learning can automatically fit image features,and use features to classify and predict images.This study introduced the improved Vision Transformer(ViT)method for crop pest image recognition.Among them,the region with the most obvious features can be effectively selected by block partition.The self-attention mechanism of the transformer can better excavate the special solution that is not an obvious lesion area.In the experiment,data with 7 classes of examples are used for verification.It can be illustrated from results that this method has high accuracy and can give full play to the advantages of image processing and recognition technology,accurately judge the crop diseases and pests category,provide method reference for agricultural diseases and pests identification research,and further optimize the crop diseases and pests control work for agricultural workers in need.

A Vertex-Centered Arbitrary Lagrangian-Eulerian Finite Volume Method with Sub-Cells for Two-Dimensional Compressible Flow

In this paper,we present a new vertex-centered arbitrary LagrangianEulerian(ALE)finite volume scheme for two-dimensional compressible flow.In our scheme,the momentum equation is discretized on the vertex control volume,while the mass equation and the energy equation are discretized on the sub-cells which are included in the vertex control volume.We attain the average of the fluid velocity on the vertex control volume directly by solving the conservation equations.Then we can obtain the fluid velocity at vertex with the reconstructed polynomial of the velocity.This fluid velocity is chosen as the mesh velocity,which makes the mesh move in a Lagrangian manner.Two WENO(Weighted Essentially Non-Oscillatory)reconstructions for the density(the total energy)and the velocity are used to make our scheme achieve the anticipated accuracy.Compared with the general vertexcentered schemes,our scheme with the new approach for the space discretization can simulate some multi-material flows which do not involve large deformations.In addition,our scheme has good robustness,and some numerical examples are presented to demonstrate the anticipated accuracy and the good properties of our scheme.

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.