Selenium–nitrogen-co-doped carbon dots increase rice seedling growth and salt resistance

Soil salinity seriously affects the utilization of farmland and threatens the crop production.Here,a selenium-nitrogen-co-doped carbon dots was developed,which increased rice seedling growth and alleviated its inhibition by salt stress by foliar spraying.The treatment activated Ca^(2+)and jasmonic acid signaling pathways and increased iron homeostasis,antioxidant defense,and cell wall development of rice seedlings.It could be used to increase crop resistance to environmental stress.

Single-atom catalysis for carbon neutrality

Currently,more than 86%of global energy consumption is still mainly dependent on traditional fossil fuels,which causes resource scarcity and even emission of high amounts of carbon dioxide(CO_(2)),resulting in a severe“Greenhouse effect.”Considering this situation,the concept of“carbon neutrality”has been put forward by 125 countries one after another.To achieve the goals of“carbon neutrality,”two main strategies to reduce CO_(2) emissions and develop sustainable clean energy can be adopted.Notably,these are crucial for the synthesis of advanced single-atom catalysts(SACs)for energyrelated applications.In this review,we highlight unique SACs for conversion of CO_(2) into high-efficiency carbon energy,for example,through photocatalytic,electrocatalytic,and thermal catalytic hydrogenation technologies,to convert CO_(2) into hydrocarbon fuels(CO,CH_(4),HCOOH,CH_(3)OH,and multicarbon[C_(2+)]products).In addition,we introduce advanced energy conversion technologies and devices to replace traditional polluting fossil fuels,such as photocatalytic and electrocatalytic water splitting to produce hydrogen energy and a high-efficiency oxygen reduction reaction(ORR)for fuel cells.Impressively,several representative examples of SACs(including d-,ds-,p-,and f-blocks)for CO_(2) conversion,water splitting to H2,and ORR are discussed to describe synthesis methods,characterization,and corresponding catalytic activity.Finally,this review concludes with a description of the challenges and outlooks for future applications of SACs in contributing toward carbon neutrality.

A literature review of MOF derivatives of electromagnetic wave absorbers mainly based on pyrolysis

Growing electromagnetic pollution has plagued researchers in the field of electromagnetic(EM)energy dissipation for many years;it is increasingly important to solve this problem efficiently.Metal-organic frameworks(MOFs),a shining star of functional materials,have attracted great attention for their advantages,which include highly tunable porosity,structure,and versatility.MOF-derived electromagnetic wave(EMW)absorbers,with advantages such as light weight,thin matching thickness,strong capacity,and wide effective bandwidth,are widely reported.However,current studies lack a systematic summary of the ternary synergistic effects of the precursor component-structure-EMW absorption behavior of MOF derivatives.Here we describe in detail the electromagnetic(EM)energy dissipation mechanism and strategy for preparing MOF-derived EMW absorbers.On the basis of this description,the following means are suggested for adjusting the EM parameters of MOF derivatives,achieving excellent EM energy dissipation:(1)changing the metal and ligands to regulate the chemical composition and morphology of the precursor,(2)controlling pyrolysis parameters(including temperature,heating rate,and gas atmosphere)to manipulate the structure and components of derivatives,and(3)compounding with enhancement phases,including carbon nanomaterials,metals,or other MOFs.

Clinical and functional comparison of dynamic hip screws and intramedullary nails for treating proximal femur metastases in older individuals

Objective:To compare the outcomes of dynamic hip screws(DHS)and intramedullary nailing(IMN)in the treatment of extra-capsular metastatic carcinoma of the proximal femur.Methods:A retrospective case analysis method was used to examine data of patients with proximal metastatic cancer of the femur who were treated with internal fixation in Department of Orthopaedics,Beijing Friendship Hospital,from January 2007 to December 2018.Blood loss,postoperative pain,functional score,length of stay,and survival rates were compared,and postoperative complications were assessed.Results:Complete follow-up data were available for 33 patients.The mean follow-up period was 12.2±3.6(range:9-32)months and the average age was 72.3±4.7(range:59-83)years old.There were 20 females and 13 males.Twenty-three patients had undergone IMN and 10 DHS,according to bone defects and the patient’s overall condition.The median survival time was 10 months in the IMN group and 11 months in the DHS group.Duration of surgery(t=-7.366,P<0.001)and length of hospital stay(t=-3.509,P<0.001)differed significantly between the two groups.There was one case of breakage of internal fixation in the IMN group.Conclusions:There was no significant difference between DHS and IMN in terms of surgical efficacy.IMN and DHS were different in terms of surgical time and hospital stay.However,due to the limited number of cases in this study,multi-factor analysis has not been performed and needs to be further verified in future analysis.When developing a surgical plan,it is recommended to consider the patient’s condition and the surgeon’s experience.

Cloning of multicopper oxidase gene from <i>Ochrobactrum sp</i>. 531 and characterization of its alkaline laccase activity towards phenolic substrates

A 1602 bp fragment was cloned from a soil bacterium Ochrobactrum sp. 531. It contained an open reading frame (ORF) of 1092 bp which was identified as a multicopper oxidase (MCO) with potential laccase activity. After inserting the cloned gene into the expression vector pET23a, it was expressed in E. coli BL21(DE3)pLysS, and its product was purified to homogeneity through chromatography. The Ochrobactrum sp. 531 MCO, consisting of 533 amino acids with a molecular mass of 57.8 kDa, was quite stable in neutral pH and showed laccase-like activity oxidizing 2,6-dimethoxyphenol (DMP), 2,2’-azino-bis(3-ethylbe- nzthiazolinesulfonic acid) (ABTS), and syringaldazine (SGZ). The enzyme showed optimum activity towards DMP, ABTS, and SGZ at the pH 8.0, 3.6, and 7.5 respectively. Kinetic studies gave this enzyme Km, kcat and kcat//Km values of: 0.09 mM, 7.94 s–1, and 88.22 s–1?mM–1 for DMP;0.072 mM, 2.95 s–1, and 40.97 s–1.mM–1 for ABTS;and 0.015 mM, 2.4 s–1, and 160 s–1.mM–1 for SGZ. Our results demonstrate that Ochrobactrum sp. 531 MCO is a bacterial laccase which oxidized phenolic substrates DMP and SGZ effectively under alkaline conditions. These unusual properties make the enzyme an interesting biocatalyst in applications for which classical laccases are unsuitable.

Mechanistic understanding of the charge storage processes in FeF_(2) aggregates assembled with cylindrical nanoparticles as a cathode material for lithium-ion batteries by in situ magnetometry

Transition metal fluorides(TMFs)cathode materials have shown extraordinary promises for electrochemical energy storage,but the understanding of their electrochemical reaction mechanisms is still a matter of debate due to the complicated and continuous changing in the battery internal environment.Here,we design a novel iron fluoride(FeF_(2))aggregate assembled with cylindrical nanoparticles as cathode material to build FeF_(2) lithium-ion batteries(LIBs)and employ advanced in situ magnetometry to detect their intrinsic electronic structure during cycling in real time.The results show that FeF_(2) cannot be involved in complete conversion reactions when the FeF_(2) LIBs operate between the conventional voltage range of 1.0–4.0 V,and that the corresponding conversion ratio of FeF_(2) can be further estimated.Importantly,we first demonstrate that the spin-polarized surface capacitance exists in the FeF_(2) cathode by monitoring the magnetic responses over various voltage ranges.The research presents an original and insightful method to examine the conversion mechanism of TMFs and significantly provides an important reference for the future artificial design of energy systems based on spinpolarized surface capacitance.

Modeling and Simulation of a Hybrid Jet-Impingement/Micro-Channel Heat Sink

With the progressive increase in the number of transistors that can be accommodated on a single integrated circuit,new strategies are needed to extract heat from these devices in an efficient way.In this regard methods based on the combination of the so-called“jet impingement”and“micro-channel”approaches seem extremely promising for possible improvement and future applications in electronics as well as the aerospace and biomedical fields.In this paper,a hybrid heat sink based on these two technologies is analysed in the frame of an integrated model.Dedicated CFD simulation of the coupled flow/temperature fields and orthogonal tests are performed in order to optimize the overall design.The influence of different sets of structural parameters on the cooling performance is examined.It is shown that an optimal scheme exists for which favourable performance can be obtained in terms of hot spot temperature decrease and thermal uniformity improvement.

Experimental study of density gradient-driven micro-instabilities and the confinement degradation during H-mode in EAST

A broadband(BB)mode is observed by collective Thomson scattering diagnostics in repeatable shots of EAST and analyzed for the first time.This BB mode usually grows during L–H transitions,featuring a BB quasi-coherent mode with increasing frequency.During H-mode operations,it is characterized by steady-state BB in the high-frequency range(f~200–2000 k Hz),at the electron scale(k_(θ)ρ_(s)=1–2),mainly driven by the density gradient,and is sensitive to the value ofηein the region of interest(ρ=0.4–0.8),wherehe=(R/L_(Te))/(R/L_(ne))is the ratio of the normalized electron temperature gradient and density gradient,and the regionρ=0.4–0.8 usually has a relatively low collisionality(v_(eff)<5).The frequency of BB is found to be dependent on the electron temperature and density gradient,which is a typical feature of electron-driven turbulence.A negative correlation between the energy confinement and the intensity of the BB turbulence during H-mode has been found,which indicates a strong electron thermal transport induced by the BB turbulence.The BB significantly decreases the electron temperature and causes flatter electron temperature profiles in the region of interest(ρ=0.4–0.8),thus makingηedecrease and the BB destabilize further.These characteristics of BB are related to the theoretical density gradient-driven trapped electron mode.It should be noted that this mode is not observed by other diagnostics in EAST,and shows very different features to the coherent modes in the edge.

A Method of Evaluating the Effectiveness of a Hydraulic Oscillator in Horizontal Wells

Bent-housing motor is the most widely used directional drilling tool,but it often encounters the problem of high friction when sliding drilling in horizontal wells.In this paper,a mathematical model is proposed to simulate slide drilling with a friction reduction tool of axial vibration.A term called dynamic effective tractoring force(DETF)is defined and used to evaluate friction reduction effectiveness.The factors influencing the DETF are studied,and the tool placement optimization problem is investigated.The studyfinds that the drilling rate of penetration(ROP)can lower the DETF but does not change the trend of the DETF curve.To effectively work,the shock tool stiffness must be greater than some critical value.For the case study,the best oscillating frequency is within 15∼20 Hz.The reflection of the vibration at the bit boundary can intensify or weaken the friction reduction effec-tiveness,depending on the distance between the hydraulic oscillator and the bit.The optimal placement position corresponds to the plateau stage of the DETF curve.The reliability of the method is verified by thefield tests.The proposed method can provide a design and use guide to hydraulic oscillators and improve friction reduction effectiveness in horizontal wells.

湖泊沉积物中磷化氢的释放动力学初探

采用柱状芯样模拟法,研究了太湖沉积物-水界面磷化氢的释放动力学.结果表明:当沉积物-水界面磷化氢的释放达到动态平衡时,水界面中磷化氢的浓度基本不再增大,大约在0.34pg·l^(-1)左右,此时磷化氢的释放通量约为0.008pg·dm^(-2)·h^(-1).根据室内模拟结果,太湖沉积物每年的磷化氢释放量在13.81—49.62g之间,从而使磷化氢在湖水中的平均浓度达到0.16pmol·l^(-1).

Investigation of the First Spermatorrhea Age of Males in Jiangsu Province, China

Background: The growth of adolescents is affected by economic development and education levels. We investigated the first spermatorrhea age of adolescents in urban area and in rural area of Jiangsu province, China. Methods: The data were obtained through anonymous questionnaire by using cross-sectional methods. From May 2016 to March 2017 in Jiangsu province, China, a total of 2131 Han nationality students were enrolled in cluster. The survey was contained date of birth, age, grade, age of first spermatorrhea and how long ago of the first spermatorrhea, all data were analyzed by Prism 8.0. Results: The questionnaire accounted for response was 97.3%, and the effective rate was 96.3%. The mean age of first spermatorrhea was (13.7 ± 1.5) years old, which included 13.6 ± 1.4 years in urban and 13.9 ± 1.5 years in rural. The first spermatorrhea occurred in the fifth and sixth grade primary school, and 1, 2, 3 grades of junior high school were 3.5%, 13%, 27.4%, 28.5% and 15.1%, respectively. There was 62.3% of first spermatorrhea occurred in summer. The rate of spermatorrhea with natural occurrence accounted for 95.1%, and with active accounted for 4.9%. Conclusions: Compared with rural area, the age of the first spermatorrhea of males in urban area is significant earlier. The adolescent’s first spermatozoa were mostly occurred in summer. The relevant physical and reproductive education should be started from the third grade of primary school. The reproductive health education should be carried out when the youth are 7 years old.

双重可逆交联互穿网络聚合物的制备与表征

以三联吡啶修饰聚己内酯(PCL-Tpy)、蒽修饰聚四氢呋喃(PTMEG-An)制备得到2种线型结构聚氨酯,混合后向其中先加入金属离子再施加紫外辐照形成热可逆的三联吡啶-金属离子配位键与光可逆的双蒽环加成2种交联,制备出双重可逆交联的动态互穿网络(IPN)聚氨酯,利用核磁共振与红外光谱对交联剂和预交联聚合物的化学结构进行表征。紫外-可见吸收光谱、差示扫描量热分析(DSC)与凝胶含量测试表明,蒽交联聚合物随辐照时间加长交联度增加;DSC的测试结果表明,Zn^(2+),Sn^(2+)与Ni^(2+)作为配位中心交联强度与可逆温度区间不同;IPN样品中两相均成形成了交联网络。表征结果表明,设计制备的该IPN样品结构在紫外光与热的多重刺激下分子结构可实现由线型到Semi-IPN以及IPN的可逆转变,两相交联性能容易调控。

Atom-level interfacial synergy of single-atom site catalysts for electrocatalysis

Single-atom site catalysts(SACs)have made great achievements due to their nearly 100%atomic utilization and uniform active sites.Regulating the surrounding environment of active sites,including electron structure and coordination environment via atom-level interface regulation,to design and construct an advanced SACs is of great significance for boosting electrocatalytic reactions.In this review,we systemically summarized the fundamental understandings and intrinsic mechanisms of SACs for electrocatalytic applications based on the interface site regulations.We elaborated the several different regulation strategies of SACs to demonstrate their ascendancy in electrocatalytic applications.Firstly,the interfacial electronic interaction was presented to reveal the electron transfer behavior of active sites.Secondly,the different coordination structures of metal active center coordinated with two or three non-metal elements were also summarized.In addition,other atom-level interfaces of SACs,including metal atom–atom interface,metal atom-X-atom interface(X:non-metal element),metal atom-particle interface,were highlighted and the corresponding promoting effect towards electrocatalysis was disclosed.Finally,we outlooked the limitations,perspectives and challenges of SACs based on atomic interface regulation.

Process analysis of temperature swing adsorption and temperature vacuum swing adsorption in VOCs recovery from activated carbon

In order to better guide the design of industrial process for purification and recovery of VOCs,temperature swing adsorption(TSA)and temperature vacuum swing adsorption(TVSA)process for VOCs purification and recovery were studied systematically with activated carbon adsorbent.The adsorption and desorption behaviors of benzene on activated carbon in above two processes were investigated systematically.Effects of operating parameters on process performances were further analyzed,including as regeneration temperature,purging feed ratio and hot–cold purging ratio.The results showed that the increase of hot–cold purging ratio(HP/CP)could obtain the same regeneration effect as the increase of desorption temperature.Increasing the feed purge ratio without increasing the hot–cold purging ratio is not conducive to bed regeneration,because a large number of cold purge gases cannot utilize the residual heat of temperature wave,thus reducing the desorption effect of the cooling step on the bed.In addition,the vacuum step can enhance the regeneration ability of hot nitrogen to the bed at the same regeneration temperature,making the bed regeneration of TVSA process more thorough.Temperature in the middle and lower part of the bed in TVSA process was higher and the regeneration was more thorough.In conclusion,TVSA has more obvious advantages than TSA in terms of energy consumption,hot or cold purge volume and bed regeneration.

Review of recent progress in studies on noise emanating from rail transit bridges

In recent years, there has been rapid growth of Chinese rail transit networks. Many of these networks require elevated bridges. This results in a bridge-borne noise source, which occurs in addition to the main noise source （i.e., wheel-rail interactions）. Bridge-borne noise is attracting increasing attention because of its low-frequency noise characteristics. This review paper first analyzes the space distribution, spectral characteristics, and sound pressure levels of noise radiated by all-concrete, steel- concrete composite, and all-steel bridges, mainly according to experimental studies. Second, this paper reviews exist- ing theoretical prediction models of noise emanating from bridges： the semianalytical method, the Rayleigh integral method, the boundary element method, and statistical energy analysis. Several case studies are reviewed, and their results are discussed. Finally, according to the results of the current review, the main factors affecting bridgeborne noise are analyzed, several noise reduction measures are proposed for different types of bridges, and their effectiveness is demonstrated.

A CFD model for gas uniform distribution in turbulent flow for the production of titanium pigment in chloride process

The fluid dynamic behavior of feeding gas （TiCI4） in an annular channel affects the combination of 02 and TiCI4 in an oxidation reactor, a key piece of equipment in titanium pigment production. The numerical procedure was validated by a 3-dimensional gas flow in the annular channel. Applying the validated model, the flow character- istics of TiCl4 in the oxidation reactor with a tangential inlet were simulated and characterized. The flow distribu- tion with five rectifying rings of different structure was simulated and analyzed. The results showed that the rectifying ring improved the distribution uniformity of the pressure and outlet velocity. Compared to the original case without a rectifying ring, the non-uniformity of the pressure and outlet velocity could be reduced by up to 91% and 69% respectively. The rectifying ring #5, which can be installed and adjusted easily, is more effective in realizing even distribution. In addition, installation of the rectifying ring effectively reduced the circulating flow in an annular channel as well as the total energy loss.

Theory-oriented screening and discovery of advanced energy transformation materials in electrocatalysis

Various metal-based electrocatalysts from nanocrystals,to clusters and single-atoms,have been well-discovered towards high-efficient power devices and electrocatalytic conversion.To accelerate energy transformation materials discovery,developing high-throughput DFT calculations and machine-learning techniques is of great necessity.This review comprehensively outlines the latest progress of theory-guided design of advanced energy transformation materials.Especially,we focus on the study of single atoms in various power devices,such as fuel cell(oxygen reduction reaction,ORR;acid oxidation reaction;alcohol oxidation reaction),and other reactions for energy-related electrocatalytic conversion of small molecules,such as H_(2)O_(2)evolution reactions(2e−ORR),water splitting(H_(2)evolution reaction/O_(2)evolution reaction,HER/OER),N2 reduction reaction(NRR),and CO_(2)reduction reactions(CO_(2)RR).Firstly,the electronic structure,interaction mechanism,and reaction activation path are discussed to provide an overall blueprint in electrocatalysis and batteries mentioned above.Thereafter,the experimental synthesis strategies,structural recognition,and electrocatalytic performance for the advanced energy transformation materials are figured out.Finally,some viewpoints into the current issues and future design concept of the advanced energy transformation materials are provided.

卡泊芬净与伏立康唑治疗侵袭性真菌感染的疗效评价

目的给予侵袭性真菌感染患者卡泊芬净配合伏立康唑治疗,评价临床疗效。方法选取本文治疗的侵袭性真菌感染患者80例(2016年3月-2018年10月),按照患者入院日期单双号予以分组,每组40例,试验组采用卡泊芬净和伏立康唑配合治疗方案,对照组采用单纯卡泊芬净治疗方案,观察患者治疗效果。结果相比于对照组,试验组临床治疗有效计算率较高,P<0.05;相比于对照组,试验组真菌清除计算率较高,P<0.05。结论在侵袭性真菌感染患者治疗中,卡泊芬净配合伏立康唑治疗,患者治疗有效状况显著提升,真菌清除效果较好。

Construction of phosphorus-doping with spontaneously developed selenium vacancies: Inducing superior ion-diffusion kinetics in hollow Cu_(2)Se@C nanospheres for efficient sodium storage

Achieving high-efficiency sodium storage in metal selenides is still severely constrained in consideration of their inferior electronic conductivity and inadequate Na^(+)insertion pathways and active sites.Heteroatom doping accompanied by spontaneously developed lattice defects can effectively tune electronic structure of metal selenides,which give a strong effect to motivate fast charge transfer and Na^(+)accessibility.Herein,we finely designed and successfully constructed a fascinating phosphorus-doped Cu_(2)Se@C hollow nanosphere with abundant vacancy defects(Cu_(2)P_(x)Se_(1-x)@C)through a combination strategy of selenization of Cu_(2)O nanosphere template,self-polymerization of dopamine,and subsequent phosphorization treatment.Such exquisite composite possesses enriched active sites,superior conductivity,and sufficient Na^(+)insertion channel,which enable much faster Na^(+)diffusion rates and more remarkable pseudocapacitive features,Satisfyingly,the Cu_(2)P_(x)Se_(1-x)@C composites manifest the supernormal sodium-storage capabilities,that is,a reversible capacity of 403.7 mA h g^(-1) at 1.0 A g^(-1) over 100 cycles,and an ultrastable cyclic lifespan over 1000 cycles at 20.0 A g^(-1) with a high capacity-retention of about249.7 mA h g^(-1).The phase transformation of the Cu_(2)P_(x)Se_(1-x)@C involving the intercalation of Na^(+)into Cu_(2)Se and the following conversion of NaCuSe to Cu and Na2Se were further demonstrated through a series of ex-situ characterization methods.DFT results demonstrate that the coexistence of phosphorusdoping and vacancy defects within Cu_(2)Se results in the reduction of Na^(+)adsorption energy from-1.47to-1.56 eV improving the conductivity of Cu_(2)Se to further accelerate fast Na^(+)mobility.

Analysis of the stress intensity factor of welded joints under prior corrosion and complex stress fields

Taking cruciform welded joints under different corrosion degrees, together with 45° inclined angle and full penetration load-carrying fillet, as the research object, the stress intensity factor of a quarter-circular comer crack of welded joints is calculated based on FRANC3D with ABAQUS. Effects of different corrosion pit sizes, crack aspect ratios, and crack depths on stress intensity factor are analyzed. The results show that pit depth plays a major role in stress intensity factor, while the effect of pit radius is relatively small. The cracking modes of the surface and the deepest point are mode I, and mixed modes I and II, respectively. Effects of pit depths, crack aspect ratios, and crack depths on the stress intensity factor at the surface point are greater than at the deepest point.