多配位水分子的焦磷酸锰用于电催化水氧化研究

自然界水氧化中心Mn_(4)CaO_(5)团簇中的配位水被认为在促进水氧化方面起着重要作用.许多报道模拟了Mn_(4)CaO_(5)结构并研究了其析氧反应(OER)过程,但配位水结构难以模拟,在OER过程中的具体功能尚不明确.目前,揭示配位水在OER中的具体作用存在以下挑战.首先,大多数锰基材料的配位结构,特别是表面结构是模糊的,导致结构-性能相关性难以确定.其次,在Mn位点上引入配位水时,往往不可避免地会改变Mn中心的核心结构,甚至改变Mn的化合价,这些干扰因素可能严重混淆配位水对OER的影响,不利于探究OER过程中配位水分子的作用.因此,构建一个理想的催化剂平台用于研究配位水分子在水氧化过程中的作用具有重要意义.本文提出了一种研究OER过程中配位水分子作用的有效方法,并阐明了OER过程中源于锰中心配位水分子结构-活性关系.采用水热法合成了一种结晶型焦磷酸锰(crystalline MnPi).在相同起始物料比、不同反应条件下,采用共沉淀法制备了分子式相同的非晶型焦磷酸锰(amorphous MnPi).通过X射线衍射、红外光谱、拉曼光谱、热重分析和理论模拟,确定了MnPi催化剂的晶体结构(Mn_(2)P_(2)O_(7)·3H_(2)O).在0.05 mol L^(-1)pH=7.0的磷酸盐缓冲溶液中,crystalline MnPi催化剂比amorphous MnPi催化剂表现出更好的OER活性.晶体结构研究结果表明,crystalline MnPi催化剂暴露的Mn位点上含有四个配位水分子,并且相邻Mn位点通过氢键相互连接形成连续的氢键网络结构.连续的氢键网络使氧原子的电荷中和水平更高,使得crystalline MnPi催化剂中Mn^(Ⅱ/Ⅲ)转换更容易,进一步揭示了配位水在水氧化机理中扮演的重要角色.详细的电化学动力学研究、原位/非原位表面表征和理论计算结果表明,crystalline MnPi催化剂的Mn^(Ⅱ/Ⅲ)氧化过程在动力学和热力学上都比amorphous MnPi催化剂容易发生.同时,crystalline MnPi催化剂中配位水分管子有效参与了Mn(Ⅱ)到Mn(Ⅲ)的质子耦合电子转移过程,此过程是锰基体系中水氧化反应中的起始关键步骤.pH动力学实验结果表明,amorphous MnPi催化剂的Mn^(Ⅱ/Ⅲ)氧化步骤为常见的2H^(+)/le单位点过程.然而,由于crystalline MnPi催化剂表面暴露的Mn位点上存在多个配位水分子,导致crystalline MnPi催化剂的Mn^(Ⅱ/Ⅲ)氧化步骤为3H^(+)/2e双位点过程.双位点上的三个配位水分子失去三个质子生成三个OH基团,OH基团通过彼此之间以及与周围配位水分子之间的氢键来有效稳定中间体电荷,进而促进水氧化的发生.综上所述,以精心设计的催化剂平台进行对比研究,直观地观察和理解了配位水分子对电催化水氧化的重要作用,为阐明锰基催化体系中配位水分子在水氧化过程中的重要作用提供了有价值的见解.

Efficient and rapid capture of uranium(Ⅵ) in wastewater via multiamine modified β-cyclodextrin porous polymer

It is quite important to ensure the safety and sustainable development of nuclear energy for the treatment of radioactive wastewater. To treat radioactive wastewater efficiently and rapidly, two multi-amine β-cyclodextrin polymers(diethylenetriamine β-cyclodextrin polymer(DETA-TFCDP) and triethylenetetramine β-cyclodextrin polymer(TETA-TFCDP)) were prepared and applied to capture uranium. Results exhibited that DETA-TFCDP and TETA-TFCDP displayed the advantages of high adsorption amounts(612.2and 628.2 mg·g-1, respectively) and rapid adsorption rates, which can reach(88 ± 1)% of their equilibrium adsorption amounts in 10 min. Moreover, the adsorbent processes of DETA-TFCDP and TETATFCDP on uranium(Ⅵ) followed the Langmuir model and pseudo-second-order model, stating they were mainly chemisorption and self-endothermic. Besides, TETA-TFCDP also showed excellent selectivity in the presence of seven competing cations and could be effectively reused five times via Na2CO3as the desorption reagent. Meanwhile, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy illustrated that the enriched multi-amine groups and oxygen-containing functional groups on the surface of TETA-TFCDP were the main active sites for capturing uranium(Ⅵ). Hence, multi-amine β-cyclodextrin polymers are a highly efficient, rapid, and promising adsorbent for capturing uranium(Ⅵ)from radioactive wastewater.

Map-based cloning of q LP_(A01.1),a favorable allele from the Gossypium tomentosum chromosome segment line

Cotton is an important natural fiber crop worldwide which plays a vital role in our daily life.High yield is a constant goal of cotton breeding,and lint percentage(LP)is one of the important components of cotton fiber yield.A stable QTL controlling LP,qLP_(A01.1),was identified on chromosome A01 from Gossypium hirsutum introgressed lines with G.tomentosum chromosome segments in a previous study.To fine-map qLP_(A01.1),an F2 population with 986individuals was established by crossing G.hirsutum cultivar CCRI35 with the chromosome segment substitution line HT_390.A high-resolution genetic map including 47 loci and spanning 56.98 cM was constructed in the QTL region,and qLP_(A01.1)was ultimately mapped into an interval corresponding to an~80 kb genome region of chromosome A01in the reference genome,which contained six annotated genes.Transcriptome data and sequence analysis revealed that S-acyltransferase protein 24(GoPAT24)might be the target gene of qLP_(A01.1).This result provides the basis for cotton fiber yield improvement via marker-assisted selection(MAS)and further studies on the mechanism of cotton fiber development.

Detection accuracy of target accelerations based on vortex electromagnetic wave in keyhole space

The influence of the longitudinal acceleration and the angular acceleration of detecting target based on vortex electromagnetic waves in keyhole space are analyzed.The spectrum spreads of different orbital angular momentum(OAM)modes in different non-line-of-sight situations are simulated.The errors of target accelerations in detection are calculated and compared based on the OAM spectra spreading by using two combinations of composite OAM modes in the keyhole space.According to the research,the effects about spectrum spreads of higher OAM modes are more obvious.The error in detection is mainly affected by OAM spectrum spreading,which can be reduced by reasonably using different combinations of OAM modes in different practical situations.The above results provide a reference idea for investigating keyhole effect when vortex electromagnetic wave is used to detect accelerations.

Quantum Spin Exchange Interactions to Accelerate the Redox Kinetics in Li–S Batteries

Spin-engineering with electrocatalysts have been exploited to suppress the“shuttle effect”in Li–S batteries.Spin selec-tion,spin-dependent electron mobility and spin potentials in activation barriers can be optimized as quantum spin exchange interactions lead-ing to a significant reduction of the electronic repulsions in the orbitals of catalysts.Herein,we anchor the MgPc molecules on fluorinated carbon nanotubes(MgPc@FCNT),which exhibits the single active Mg sites with axial displacement.According to the density functional theory calculations,the electronic spin polarization in MgPc@FCNT not only increases the adsorption energy toward LiPSs intermediates but also facilitates the tunneling process of electron in Li–S batter-ies.As a result,the MgPc@FCNT provides an initial capacity of 6.1 mAh cm^(-2) even when the high sulfur loading is 4.5 mg cm^(-2),and still maintains 5.1 mAh cm^(-2) after 100 cycles.This work provides a new perspective to extend the main group single-atom catalysts enabling high-performance Li–S batteries.

A sustainable process to 100%bio-based nylons integrated chemical and biological conversion of lignocellulose

Considerable progress has been made in recent years to the development of sustainable polymers from bio-based feedstocks.In this study,100%bio-based nylons were prepared via an integrated chemical and biological process from lignocellulose.These novel nylons were obtained by the melt polymerization of 3-propyladipic acid derived from lignin and 1,5-pentenediamine/1,4-butanediamine derived from carbohydrate sugar.Central to the concept is a three-step noble metal free catalytic chemical funnelling sequence(Raney Ni mediated reductive catalytic fractionation-reductive funnelling-oxidative funnelling),which allowed for obtaining a single component 3-propyladipic acid from lignin with high efficiency.The structural and thermodynamic properties of the obtained nylons have been systematically investigated,and thus obtained transparent bio-based nylons exhibited higher Mw(>32,000)and excellent thermal stability(Td5%>265℃).Considering their moderate Tg and good melt strength,these transparent bio-based nylons could serve as promising functional additives or temperature-responsive materials.

Research on batch multielement rapid quantitative analysis based on the standard curve-assisted calibration-free laserinduced breakdown spectroscopy method

This study proposes a batch rapid quantitative analysis method for multiple elements by combining the advantages of standard curve(SC)and calibration-free laser-induced breakdown spectroscopy(CF-LIBS)technology to achieve synchronous,rapid,and accurate measurement of elements in a large number of samples,namely,SC-assisted CF-LIBS.Al alloy standard samples,divided into calibration and test samples,were applied to validate the proposed method.SC was built based on the characteristic line of Pb and Cr in the calibration sample,and the contents of Pb and Cr in the test sample were calculated with relative errors of 6%and 4%,respectively.SC built using Cr with multiple characteristic lines yielded better calculation results.The relative contents of ten elements in the test sample were calculated using CF-LIBS.Subsequently,the SC-assisted CF-LIBS was executed,with the majority of the calculation relative errors falling within the range of 2%-5%.Finally,the Al and Na contents of the Al alloy were predicted.The results demonstrate that it effectively enables the rapid and accurate quantitative analysis of multiple elements after a single-element SC analysis of the tested samples.Furthermore,this quantitative analysis method was successfully applied to soil and Astragalus samples,realizing an accurate calculation of the contents of multiple elements.Thus,it is important to advance the LIBS quantitative analysis and its related applications.

P7脂肽的合成工艺与生物活性研究

对P7脂肽的合成工艺及生物活性进行研究。采用固相多肽法(SPPS)和疏水载体辅助液相法(LPPS)人工合成P7脂肽;利用分子对接技术将合成的化合物与受体蛋白(3OCG)进行对接;采用MTT法与Griess试剂法检测P7脂肽的生物毒性和抗炎活性。成功合成P7脂肽并对其进行质谱表征;SPPS法与LPPS法的收率分别为34.45%和66.31%,物料消耗量分别为129.12和83.08 g,废液产生量分别为7.12和3.38 L,PMI分别为30.81,10.29,E-因子分别为1 700.62,419.70;分子对接结果表明,P7脂肽与p38蛋白激酶(3OCG)的对接结合能最小,GHK分子与残基ARG67、LYS53和GLY36形成氢键,P7肽与残基ALAA34、TYRA35、THRA185形成氢键,P7脂肽与残基ARGA70、ARGA189、TYRA35、ARGA67、ASNA155、ASPA168形成氢键并与残基存在范德华力、pi-烷基、C-H键等相互作用力;P7脂肽在32μmol/L浓度以内无生物毒性;不同浓度的P7脂肽对LPS诱导RAW264.7细胞炎症模型中NO的释放具有很好的下调作用。通过对P7脂肽的合成研究,表明LPPS法的总体收率比SPPS法收率高且物料消耗量及“三废”产生量少,更适合于工业化生产;分子对接与细胞实验结果表明设计合成的P7脂肽具有良好的抗炎抗骨质疏松活性。

Retraction Note:Hydralazine Promotes Central Nervous System Recovery after Spinal Cord Injury by Suppressing Oxidative Stress and Inflammation through Macrophage Regulation

The Editor-in-Chief has retracted this article on the corresponding authors'request.The corresponding authors on behalf of all the authors stated that the data presented in this article does not belong to the named authors,but belongs to Prof.Sheng-xi Wu and Prof.Wang Xi of the Department of Neurobiology of the Fourth Military Medical University,Xi'an,China.

Cs-Induced Phase Transformation of Vanadium Oxide for High-Performance Zinc-Ion Batteries

Rechargeable aqueous zinc-ion batteries are promising candidate for gridscale energy storage.However,the development of zinc-ion batteries has been plagued by the lack of cathode materials with high specific capacity and superior lifespan.Herein,hexagonal Cs_(0.3)V_(2)O_(5)cathode is fabricated and investigated in zinc-ion batteries.Compared with the traditional vanadium oxides,the introduction of Cs changes the periodic atomic arrangements,which not only stabilizes the open framework structure but also facilitates the Zn^(2+)diffusion with a lower migration energy barrier.Consequently,high specific capacity of 543.8 mA h g^(-1)at 0.1 A g^(-1)is achieved,which surpasses most of reported cathode materials in zinc-ion batteries.The excellent cycle life is achieved over 1000 cycles with about 87.8%capacity retention at 2 A g^(-1).Furthermore,the morphological evolution and energy storage mechanisms are also revealed via a series of techniques.This work opens up a phase engineering strategy to fabricate the hexagonal vanadium oxide and elucidate the application of phase-dependent cathodes in zinc-ion batteries.

Melatonin inhibits ESCC tumor growth by mitigating the HDAC7/β-catenin/c-Myc positive feedback loop and suppressing the USP10-maintained HDAC7 protein stability

Background:Melatonin,a natural hormone secreted by the pineal gland,has been reported to exhibit antitumor properties through diverse mechanisms of action.However,the oncostatic function of melatonin on esophageal squamous cell carcinoma(ESCC) remains elusive.This study was conducted to investigate the potential effect and underlying molecular mechanism of melatonin as single anticancer agent against ESCC cells.Methods:ESCC cell lines treated with or without melatonin were used in this study.In vitro colony formation and 5-Ethynyl-2’-deoxyuridine(EdU) incorporation assays,and nude mice tumor xenograft model were used to confirm the proliferative capacities of ESCC cells.RNA-seq,qPCR,Western blotting,recombinant lentivirus-mediated target gene overexpression or knockdown,plasmids transfection and co-IP were applied to investigate the underlying molecular mechanism by which melatonin inhibited ESCC cell growth.IHC staining on ESCC tissue microarray and further survival analyses were performed to explore the relationship between target genes’ expression and prognosis of ESCC.Results:Melatonin treatment dose-dependently inhibited the proliferative ability and the expression of histone deacetylase 7(HDAC7),c-Myc and ubiquitin-specific peptidase 10(USP10) in ESCC cells(P<0.05).The expressions of HDAC7,c-Myc and USP10 in tumors were significantly higher than the paired normal tissues from 148 ESCC patients(P<0.001).Then,the Kaplan-Meier survival analysis suggested that ESCC patients with high HDAC7,c-Myc or USP10levels predicted worse overall survival(log-rank P<0.001).Co-IP and Western blotting further revealed that HDAC7physically deacetylated and activated β-catenin thus promoting downstream target c-Myc gene transcription.Notably,our mechanistic study validated that HDAC7/β-catenin/c-Myc could form the positive feedback loop to enhance ESCC cell growth,and USP10 could deubiquitinate and stabilize HDAC7 protein in the ESCC cells.Additionally,we verified that inhibition of the HDAC7/β-catenin/c-Myc axis and USP10/HDAC7 pathway mediated the anti-proliferative action of melatonin on ESCC cells.Conclusions:Our findings elucidate that melatonin mitigates the HDAC7/β-catenin/c-Myc positive feedback loop and inhibits the USP10-maintained HDAC7 protein stability thus suppressing ESCC cell growth,and provides the reference for identifying biomarkers and therapeutic targets for ESCC.

Microfluidic field strategy for enhancement and scale up of liquid-liquid homogeneous chemical processes by optimization of 3D spiral baffle structure

Due to the scale effect, the uniform distribution of reagents in continuous flow reactor becomes bad when the channel is enlarged to tens of millimeters. Microfluidic field strategy was proposed to produce high mixing efficiency in large-scale channel. A 3D spiral baffle structure(3SBS) was designed and optimized to form microfluidic field disturbed by continuous secondary flow in millimeter scale Y-shaped tube mixer(YSTM). Enhancement effect of the 3SBS in liquid-liquid homogeneous chemical processes was verified and evaluated through the combination of simulation and experiment. Compared with 1 mm YSTM, 10 mm YSTM with 3SBS increased the treatment capacity by 100 times, shortened the basic complete mixing time by 0.85 times, which proves the potential of microfluidic field strategy in enhancement and scale-up of liquid-liquid homogeneous chemical process.

Obtaining accurate measurements of the sea surface height from a GPS buoy

A dedicated GPS buoy is designed for calibration and validation(Cal/Val)of satellite altimeters since 2014.In order to evaluate the accuracy of the sea surface height(SSH)measured by the GPS buoy,twelve campaigns have been done within China sea area between 2014 and 2021.In six of these campaigns,two static Global Navigation Satellite System stations were installed at distances of<1 km and 19 km from the buoy to assess how the baseline length influenced the derived SSH from the buoy solutions.The GPS buoy data was processed using the GAMIT/GLOBK software+TRACK module and CSRS-PPP tool to achieve the SSH.The SSH was compared with conventionally tide gauge(TG)data to evaluate the accuracy of the buoy with the standard deviation of the height element.The results showed that the difference in the standard deviation of the SSH from the buoy and the TG was less than 16 mm.The SSHs processed with different ephemeris(Ultra-Rapid,Rapid,Final)were not significantly different.When the baseline length was 19 km,the SSH solution of the GPS buoy performed well,with standard bias of less than 26 mm between the heights measured by the buoy and TG,meaning that the buoy could be used for Cal/Val of altimeters.The bias between the Canadian Spatial Reference System-precise point positioning tool and the TRACK varied a lot,and some of them were over 130 mm.This deemed too high to be useful for Cal/Val of satellite altimeters.Moreover,the GPS buoy solutions processed by GAMIT/GLOBK software+TRACK module were used for in-orbit Cal/Val of HY-2B/C satellites in ten campaigns.The SSH and significant wave height of the altimeters showed good agreements with the GPS buoy solutions.

Quantum cascade lasers grown by MOCVD

Sharing the advantages of high optical power,high efficiency and design flexibility in a compact size,quantum cascade lasers(QCLs)are excellent mid-to-far infrared laser sources for gas sensing,infrared spectroscopic,medical diagnosis,and defense applications.Metalorganic chemical vapor deposition(MOCVD)is an important technology for growing high quality semiconductor materials,and has achieved great success in the semiconductor industry due to its advantages of high efficiency,short maintenance cycles,and high stability and repeatability.The utilization of MOCVD for the growth of QCL materials holds a significant meaning for promoting the large batch production and industrial application of QCL devices.This review summarizes the recent progress of QCLs grown by MOCVD.Material quality and the structure design together determine the device performance.Research progress on the performance improvement of MOCVD-grown QCLs based on the optimization of material quality and active region structure are mainly reviewed.

Hydralazine Promotes Central Nervous System Recovery after Spinal Cord Injury by Suppressing Oxidative Stress and Inflammation through Macrophage Regulation

Objective:This study aims to investigate the effects of hydralazine on inflammation induced by spinal cord injury(SCI)in the central nervous system(CNS)and its mechanism in promoting the structural and functional recovery of the injured CNS.Methods:A compressive SCI mouse model was utilized for this investigation.Immunofluorescence and quantitative real-time polymerase chain reaction were employed to examine the levels of acrolein,acrolein-induced inflammation-related factors,and macrophages at the injury site and within the CNS.Western blotting was used to evaluate the activity of the phosphoinositide 3-kinase(PI3K)/AKT pathway to study macrophage regulation.The neuropathic pain and motor function recovery were evaluated by glutamic acid decarboxylase 65/67(GAD65/67),vesicular glutamate transporter 1(VGLUT1),paw withdrawal response,and Basso Mouse Scale score.Nissl staining and Luxol Fast Blue(LFB)staining were performed to investigate the structural recovery of the injured CNS.Results:Hydralazine downregulated the levels of acrolein,IL-1β,and TNF-αin the spinal cord.The downregulation of acrolein induced by hydralazine promoted the activation of the PI3K/AKT pathway,leading to M2 macrophage polarization,which protected neurons against SCI-induced inflammation.Additionally,hydralazine promoted the structural recovery of the injured spinal cord area.Mitigating inflammation and oxidative stress by hydralazine in the animal model alleviated neuropathic pain and altered neurotransmitter expression.Furthermore,hydralazine facilitated motor function recovery following SCI.Nissl staining and LFB staining indicated that hydralazine promoted the structural recovery of the injured CNS.Conclusion:Hydralazine,an acrolein scavenger,significantly mitigated SCI-induced inflammation and oxidative stress in vivo,modulated macrophage activation,and consequently promoted the structural and functional recovery of the injured CNS.

Correction to:Molecular characterization and functional analysis of daf-8 in the pinewood nematode,Bursaphelenchus xylophilus

Correction to:J.For.Res.(2022)33:689–698 https://doi.org/10.1007/s11676-021-01335-7 In the Original Publication,the text“Acknowledgements sdfkjds”has been inadvertently appeared in the paper.The Original article has been corrected.

Diagnostic accuracy of apparent diffusion coefficient to differentiate intrapancreatic accessory spleen from pancreatic neuroendocrine tumors

BACKGROUND Intrapancreatic accessory spleen(IPAS)shares similar imaging findings with hypervascular pancreatic neuroendocrine tumors(PNETs),which may lead to unnecessary surgery.AIM To investigate and compare the diagnostic performance of absolute apparent diffusion coefficient(ADC)and normalized ADC(lesion-to-spleen ADC ratios)in the differential diagnosis of IPAS from PNETs.METHODS A retrospective study consisting of 29 patients(16 PNET patients vs 13 IPAS patients)who underwent preoperative contrast-enhanced magnetic resonance imaging together with diffusion-weighted imaging/ADC maps between January 2017 and July 2020 was performed.Two independent reviewers measured ADC on all lesions and spleens,and normalized ADC was calculated for further analysis.The receiver operating characteristics analysis was carried out for evaluating the diagnostic performance of both absolute ADC and normalized ADC values in the differential diagnosis between IPAS and PNETs by clarifying sensitivity,specificity,and accuracy.Inter-reader reliability for the two methods was evaluated.RESULTS IPAS had a significantly lower absolute ADC(0.931±0.773×10^(-3)mm^(2)/s vs 1.254±0.219×10^(-3)mm^(2)/s)and normalized ADC value(1.154±0.167 vs 1.591±0.364)compared to PNET.A cutoff value of 1.046×10^(-3)mm^(2)/s for absolute ADC was associated with 81.25%sensitivity,100%specificity,and 89.66%accuracy with an area under the curve of 0.94(95%confidence interval:0.8536-1.000)for the differential diagnosis of IPAS from PNET.Similarly,a cutoff value of 1.342 for normalized ADC was associated with 81.25%sensitivity,92.31%specificity,and 86.21%accuracy with an area under the curve of 0.91(95%confidence interval:0.8080-1.000)for the differential diagnosis of IPAS from PNET.Both methods showed excellent inter-reader reliability with intraclass correlation coefficients for absolute ADC and ADC ratio being 0.968 and 0.976,respectively.CONCLUSION Both absolute ADC and normalized ADC values can facilitate the differentiation between IPAS and PNET.

Face recognition using both visible light image and near-infrared image and a deep network

In recent years, deep networks has achieved outstanding performance in computer vision, especially in the field of face recognition. In terms of the performance for a face recognition model based on deep network, there are two main closely related factors： 1） the structure of the deep neural network, and 2） the number and quality of training data. In real applications, illumination change is one of the most important factors that significantly affect the performance of face recognition algorithms. As for deep network models, only if there is sufficient training data that has various illumination intensity could they achieve expected performance. However, such kind of training data is hard to collect in the real world. In this paper, focusing on the illumination change challenge, we propose a deep network model which takes both visible light image and near-infrared image into account to perform face recognition. Near- infrared image, as we know, is much less sensitive to illuminations. Visible light face image contains abundant texture information which is very useful for face recognition. Thus, we design an adaptive score fusion strategy which hardly has information loss and the nearest neighbor algorithm to conduct the final classification. The experimental results demonstrate that the model is very effective in realworld scenarios and perform much better in terms of illumination change than other state-of-the-art models.

幼儿体力活动水平:基于幼儿身体活动观察记录系统的评估

中高强度的体力活动与幼儿身体素质相关显著,幼儿园应保障幼儿每天有足够的中高强度体力活动。本研究运用幼儿身体活动观察记录系统,在广东省54所幼儿园开展幼儿体力活动水平调查。结果发现,幼儿的体力活动水平整体较低,久坐行为频率高,中高强度活动频率低。不同活动类型和不同等级幼儿园在体力活动水平上差异显著,具体表现为:在平均体力活动水平方面,自由游戏与早操显著高于体育游戏,省一级、办园级显著高于市一级;在久坐行为频率方面,自由游戏显著低于早操和体育游戏,省一级显著低于市一级;在中高强度活动频率上,自由游戏显著高于体育游戏和早操,省一级显著高于市一级。幼师比偏高,生均活动面积和生均器材数量偏少,教师对户外活动中的运动安全和常规格外关注,专注于游戏情境创设,对运动量和强度关注太少,编制的早操活动结构不合理、基本体操不科学,是幼儿体力活动水平整体不高、幼儿在教师组织实施的体育游戏与早操中的体力活动水平反不如户外自由游戏的重要原因。为提高幼儿在园体力活动水平,幼儿园应合理分配户外活动类型比例,增加户外自由游戏时间;相关部门应提升教师体育素养,加强对幼儿园户外活动的专业评价与监督。

Simultaneous hydrogen and peroxide production by photocatalytic water splitting

Photocatalytic oxidation of water is a promising method to realize large-scale H2O2 production without a hazardous and energy-intensive process. In this study, we introduce a Pt/TiO2(anatase) photocatalyst to construct a simple and environmentally friendly system to achieve simultaneous H2 and H2O2 production. Both H2 and H2O2 are high-value chemicals, and their separation is automatic. Even without the assistance of a sacrificial agent, the system can reach an efficiency of 7410 and 5096 μmol g^-1 h^–1 (first 1 h) for H2 and H2O2, respectively, which is much higher than that of a commercial Pt/TiO2(anatase) system that has a similar morphology. This exceptional activity is attributed to the more favorable two-electron oxidation of water to H2O2, compared with the four-electron oxidation of water to O2.