光电催化析氧和CO_(2)还原反应催化剂的研究进展

随着日益增加的化石能源消耗和环境污染,新能源和环境友好型技术的应用对工业发展发挥着重要作用.利用太阳能及电能进行各种催化反应的光电催化(PEC)是一种有应用前景的技术,与传统催化技术相比,具有环保节能、效率高的优势.析氧反应(OER)和CO_(2)还原反应(CO_(2)RR)是两种具有能源及环境应用潜力的催化反应.PECOER对基于水氧化和其他相关氧化反应的可再生能源技术具有重要作用.PEC CO_(2)RR可以将CO_(2)转化为高附加值化学品,实现CO_(2)的合理利用.上述两种技术均具有较大的研究价值和应用前景.本综述首先阐述了电催化和光催化技术的优缺点.由于工业上使用电催化技术会消耗煤和石油等化石能源,有污染环境的风险,且长期的用电成本会影响最终的盈利;而使用光催化技术又面临着反应效率不理想、稳定性差和可见光吸收率低等缺点.一方面,PEC技术可以解决光催化中光生电子-空穴对复合速度快、反应时间长的缺点;另一方面,PEC技术可以降低电催化过程中在高电流密度下反应所需的过电位,在节省电能的同时提高反应效率.此外,系统地介绍了光电催化产氧和CO_(2)RR的机理和参数、催化剂类型、评价标准以及近年来的研究进展.对于反应条件,光电催化和电催化所使用的基础仪器基本相同,而光电催化是在电催化的基础之上施加外部光源,利用光能进一步提高反应效率和稳定性.光电催化和电催化的反应机理也基本一致,不同的是光电催化的评价标准与电催化有所不同.在光照作用下,除了关注特定电压下的电流密度、选择性和稳定性外,研究者们更关注应用偏压光子电流转换效率(ABPE)和入射光子对电流的效率(IPCE)的影响.同时,介绍了用于PEC OER和CO_(2)RR催化剂的类别、优势、合成方法、设计原则和改性策略.就目前研究而言,光电催化性能优异的催化剂一般都具有导电性良好、光吸收效率高和载流子分离速率快等特点.随着对光电催化技术研究地深入,通过掺杂、制造缺陷、设计异质结、负载单/双原子和改变反应微环境等方法有效地提升了催化效率和稳定性.在上述研究基础上,还扩展性地阐述光热催化、光酶催化等近几年的热点技术,这些技术均具有反应条件温和、过程简单和效率高等特点,在未来具有较大的研究价值.最后,展望了PEC技术的未来发展趋势和前景,重点关注了它在工业上的应用前景和价值.在未来,PEC技术将朝着智能化、创新和环保的方向发展.通过先进的理论技术(如理论计算、机器学习、分子动力学模拟等)和原位表征探索反应机理,实现低成本、绿色和智能化的技术以迎接未来实现大规模工业化的挑战,从而在盈利和环保两者之间实现“双赢”.希望本文能帮助读者更快及更全面地了解PEC技术的基本原理、常用催化剂、改性策略、拓展技术、应用前景和发展趋势,从而为读者提供可借鉴的研究思路.

Application of diffusion kurtosis imaging technology in evaluating early mild traumatic brain injury

Objective To explore the value of magnetic resonance diffusion kurtosis imaging in diagnosing early tiny changes of brain tissue after mild traumatic brain injury.Methods A total of 22 patients with mild traumatic brain injury(study group)and 20 healthy subjects(control group)were enrolled in this study,and diffusion kurtosis imaging magnetic resonance scanning was employed in all subjects.fractional anisotropy,fractional anisotropy of kurtosis,mean kurtosis,axial kurtosis and radial kurtosis of diffusion kurtosis imaging parameters in the genu of corpus callosum,splenium corporis callosi,internal capsule,thalamus,putamen,cortex of frontal lobe,temporal lobe and parietal lobe at control group,the injured side and the mirror regions were measured,and the results were compared between the two groups.The receiver operating characteristic curve was used to evaluate the ability of different parameters in diagnosing mild traumatic brain injury.Results Compared with the control group,in the study group fractional anisotropy values of bilateral genu of corpus callosum,splenium corporis callosi,internal capsule and thalamus were significantly reduced,and fractional anisotropy of kurtosis values of bilateral thalamus and putamen were significantly reduced,and the differences were statistically significant(P<0.05).Compared with the control group,in the study group mean kurtosis and axial kurtosis values of bilateral genu of corpus callosum,posterior limb of Internal capsule,thalamus,putamen and cortex of temporal lobe were significantly reduced,while radial kurtosis values in the genu of corpus callosum,thalamus,cortex of frontal lobe,temporal lobe at the injured side were increased,and the differences were statistically significant(P<0.05).Conclusion DKI techniques can sensitively detect the early tiny pathologic changes of cerebral tissue in mild traumatic brain injury patients,which provide more imaging evidence for the clinical early diagnosis treatment and prognosis.

Double active sites promoting hydrogen evolution activity and stability of CoRuOH/Co_(2)P by rapid hydrolysis

Cobalt-based phosphides show excellent hydrogen evolution reaction(HER)performance,however,improving the intrinsic activity and stability of it in alkaline electrolyte still remains a challenge.Herein,CoRuOH/Co_(2)P/CF with heterojunction structure was developed by means of molten salt and rapid hydrolysis(30 s).The OH-from rapid surface hydrolysis of Co_(2)P as a hydrogen adsorption site can facilitate the formation of thin CoRuOH layer as a water dissociation site,which may bring out better synergistic effect for alkaline HER.Moreover,the covering of CoRuOH can improve the stability of Co_(2)P for HER.When drives at 100 mA/cm^(2),it only requires overpotential of 81 mV in 1.0 mol/L KOH(25℃).Even at higher current density(1000 mA/cm^(2)),CoRuOH/Co_(2)P/CF can also operate stability for at least 100 h.When coupling with NiFe-LDH/IF in a two-electrode system,the voltage of NiFe-LDH/IF(+)||CoRuOH/Co_(2)P/CF(-)at 1000 mA/cm^(2)is merely 1.77 V with 100 h,demonstrating great potential for water splitting.The implementation of this work provides a new strategy and reference for the further improvement of transition metal phosphides as HER electrocatalysts.

Recent advances in Fe-N-C-and Co-N-C-based materials as bifunctional electrocatalysts for oxygen reduction and oxygen evolution

Fe-nitrogen-carbon(Fe-N-C)-and Co-nitrogen-carbon(Co-N-C)-based electrocatalysts have been widely concerned because of their high OER/ORR activity,low metal cost,and simple preparation.The exploration of Fe-N-C and Co-N-C single atombased catalysts with high activity and stability to overcome the slow kinetics of oxygen reduction and oxygen evolution reactions is also the key to the development of efficient electrolytic water,fuel cells,and rechargeable metal-air batteries.Fe-N-C and Co-N-C single atom-based electrocatalysts have the advantages of a high utilization rate of metal atoms and high electrocatalytic activity,and are ideal catalysts for promoting electrochemical energy conversion and storage.The general principles of designing Fe-N-C and Co-N-C single atom-based electrocatalysts are reviewed in this paper.Then,the strategies to improve the bifunctional catalytic activity and stability are proposed.Finally,the challenges and prospects of Fe-N-C and Co-N-C single atom-based catalysts are well summarized.This review will provide a reference for the directed optimization of Fe-N-C and Co-N-C single atom-based catalysts.

用于锌-空气电池空气电极的无贵金属掺杂碳基电催化剂

低成本、高能量密度、安全的锌空气电池(ZABs)被认为是最有潜力的绿色储能设备之一.然而,ZABs的性能受到多种组分性能的影响,包括锌阳极的钝化和腐蚀,电解质的碱性,特别是空气阴极上缓慢的O_(2)氧化还原反应.其中,阴极电催化剂对ZABs的性能起着至关重要的作用.氮掺杂碳基材料作为电催化剂具有价格低、稳定性好、结构可控、导电性高等优点,可有效提高ZABs的整体性能.到目前为止,该领域已经发表了大量论文,但关于ZABs用氮掺杂碳基材料的最新进展还没有系统的综述.本文对这一迅速发展的重要领域进行了及时、全面的总结.本文首先介绍了ZABs的重要组成部分和工作原理,并简要介绍了ZABs的阳极和电解液的研究进展.然后,提出了目前先进的氮掺杂碳基ZABs催化剂的优化策略,包括各种常用的氮掺杂碳催化剂的制备方法.除了不含金属的氮掺杂碳基催化剂外,还讨论了氮掺杂碳基催化剂与非贵金属偶联的研究进展.本文系统地综述了各种催化剂的性质、制备方法和详细催化机理,并对其优缺点进行了比较.本文不仅介绍了最新的研究进展,还为指导高性能氮掺杂碳基电催化剂的设计提供了基本思路,有助于其在ZABs中的大规模应用.

Crack elimination and strength enhancement mechanisms of selective laser melted Si-modified Al−Mn−Mg−Er−Zr alloy

In order to increase the processability and process window of the selective laser melting(SLM)-fabricated Al−Mn−Mg−Er−Zr alloy,a novel Si-modified Al−Mn−Mg−Er−Zr alloy was designed.The effect of Si alloying on the surface quality,processability,microstructure,and mechanical properties of the SLM-fabricated alloy was studied.The results showed that introducing Si into the Al−Mn−Mg−Er−Zr alloy prevented balling and keyhole formation,refined the grain size,and reduced the solidification temperature,which eliminated cracks and increased the processability and process window of the alloy.The maximum relative density of the SLM-fabricated Si/Al−Mn−Mg−Er−Zr alloy reached 99.6%.The yield strength and ultimate tensile strength of the alloy were(371±7)MPa and(518±6)MPa,respectively.These values were higher than those of the SLM-fabricated Al−Mn−Mg−Er−Zr and other Sc-free Al−Mg-based alloys.

H9N2,行进在新亚型流感病毒的途中（英文）

目的:分析H9N2禽流感病毒通过基因重配形成H7N9和H10N8人间禽流感病毒的进程,探讨作为供体的禽流感病毒H9N2在当前中国的主要分布及其内部6个基因节段的进化关系。创新点:人间禽流感病毒H7N9和H10N8共起源于H9N2禽流感病毒早已成为共识,但共起源的时间节点、作为供体的禽流感病毒H9N2在当前中国的分布及其内部6个基因节段的进化关系鲜有论及。2014年,H5N6禽流感被多次报道造成人类感染。研究表明,H5N6禽流感具有复杂的重配来源,H9N2正是其一,加之H7N9第五波流行的严峻形势,亟需明确H9N2禽流感病毒通过基因重配形成新亚型的能力以及它在我国的当前主要分布。方法:从流感病毒公共数据库下载基因序列,评估查找适当的碱基替代模型,通过进化树查看与H7N9、H10N8及H5N6具有高度相似性的H9N2病毒的分布地区以及它们在内部6个基因节段上的进化关系,同时通过碱基替代速率的计算追溯最近共同祖先(tMRCA)及其分歧时间。结论:人间禽流感病毒H7N9与H10N8均在2012年之前形成,短期内通过碱基替代与基因重配形成了两种可感染人类的禽流感病毒,证实了H9N2通过重配形成新亚型的高效性。作为重配供体的H9N2至今仍广布于华东、华南及东南亚。其内部基因节段的重配复杂,发生在亚型内部的重配以及通过重配形成新的病毒亚型的风险都很高,需在禽畜中加强流感病毒的流行动态监测,特别是那些一向被忽视的编码内部蛋白的基因组节段。

Improvement cues of lesion absorption using the adjuvant therapy of traditional Chinese medicine Qinbudan tablet for retreatment pulmonary tuberculosis with standard anti-tuberculosis regimen

Background:China is the second highest pulmonary tuberculosis(PTB)burden country worldwide.However,retreatment of PTB has often developed resistance to at least one of the four first-line anti-TB drugs.The cure rate(approximately 50.0–73.3%)and management of retreatment of PTB in China needs to be improved.Qinbudan decoction has been widely used to treat PTB in China since the 1960s.Previously clinical studies have shown that the Qinbudan tablet(QBDT)promoted sputum-culture negative conversion and lesion absorption.However,powerful evidence from a randomized controlled clinical trial is lacking.Therefore,the aim of this study was to compare the efficacy and safety of QBDT as an adjunct therapy for retreatment of PTB.Methods:We conducted a multicenter,randomized,double-blind,placebo-controlled clinical trial in China.People diagnosed with PTB were enrolled who received previous anti-TB treatment from April 2011 to March 2013.The treatment group received an anti-TB regimen and QBDT,and the control group was administered an anti-TB regimen plus placebo.Anti-TB treatment options included isoniazid,rifampicin,pyrazinamide,ethambutol,streptomycin for 2 months(2HRZES),followed by isoniazid,rifampicin,ethambutol for 6 months(6HRE),daily for 8 months.Primary outcome was sputum-culture conversion using the MGIT 960 liquid medium method.Secondary outcomes included lung lesion absorption and cavity closure.Adverse events and reactions were observed after treatment.A structured questionnaire was used to record demographic information and clinical symptoms of all subjects.Data analysis was performed by SPSS 25.0 software in the full analysis set(FAS)population.Results:One hundred eighty-one cases of retreatment PTB were randomly divided into two groups:the placebo group(88 cases)and the QBDT group(93 cases).A total of 166 patients completed the trial and 15 patients lost to follow-up.The culture conversion rate of the QBDT group and placebo group did not show a noticeable improvement by using the covariate sites to correct the rate differences(79.6%vs 69.3%;rate difference=0.10,95%confidence interval(CI):-0.02–0.23;F=2.48,P=0.12)after treatment.A significant 16.6%increase in lesion absorption was observed in the QBDT group when compared with the placebo group(67.7%vs 51.1%;rate difference=0.17,95%CI:0.02–0.31;χ2=5.56,P=0.02).The intervention and placebo group did not differ in terms of cavity closure(25.5%vs 21.1%;rate difference=0.04,95%CI:-0.21–0.12;χ2=0.27,P=0.60).Two patients who received chemotherapy and combined QBDT reported pruritus/nausea and vomiting.Conclusions:No significant improvement in culture conversion was observed for retreatment PTB with traditional Chinese medicine plus standard anti-TB regimen.However,QBDT as an adjunct therapy significantly promoted lesion absorption,thereby reducing lung injury due to Mycobacterium tuberculosis infection.Trial registration:This trial is registered at ClinicalTrials.gov,NCT02313610.

Research and application of Portulaca oleracea in pharmaceutical area

Portulaca oleracea, a plant species used as medicine and food, is widely spread in most areas of China. It is also a popular food in some Europe and Mediterranean countries. Purslane contains a variety of chemical constituents with pharmacological activities, such as antitumor, hypoglycemic, antioxidant, antibacterial,anti-inflammatory activities. It is also full of plenty of nutrients serving as a diet food or healthy food.Here we reviewed purslane in the following aspects: botanical resources, ethnopharmacological function,chemical constituents, pharmacology and pharmacokinetics, safety evaluation and toxicity, and clinical applications.

Formation and Structural Evolution of Fe72.5B15.6Si7.8Nb1.7Zr1.7Cu0.7 Nanocrystalline Alloy

A 2.5-mm Fe72.5B15.6Si7.8Nb1.7Zr1.7Cu0.7 glassy rod was successfully fabricated using copper mold casting.The introduction of Cu resulted in the formation of large quantities of a-Fe nanoparticles embedded in the glassy matrix after isothermal annealing.The Fe72.5B15.6Si7.8Nb1.7Zr1.7Cu0.7 nanocrystalline alloy exhibited high saturation magnetization(~1.26 T) and a low coercive force(~0.8 A/m) after annealing at 833 K for 15 min due to the precipitation of ~15-nm-sized a-Fe nanoparticles in the glassy matrix.The structural evolution of the FeBSiNbZrCu amorphous alloy during the annealing process was discussed using a dual-cluster model.

Synthesis of Star-like Polybutadienes by a Combination of Living Anionic Polymerization and “Click” Coupling Method

Three-arm and four-arm star-like polybutadienes （PBds） were synthesized via the combination of living anionic polymerization and the click coupling method. Kinetic study showed that the click reaction between the azido group terminated PBd-t-N3 and the alkyne-containing multifunctional linking reagent was fast and highly efficient. All coupling reactions were fully accomplished within 40 min at 50 ℃ in toluene in the presence of the reducing agent Cu（0）, proven by 1H-NMR, FTIR and GPC measurements. For the coupling reactions between the PBd-t-N3 polymer and dialkyne-containing compound, the final conversion of the coupled PBd-PBd polymer was ca. 97.0%. When a PBd-t-N3 polymer was reacted with trialkyne-containing or tetraalkyne-containing compound, the conversion of three-arm or four-arm PBd was around 95.5% or 87.0%, respectively. Several factors influencing the coupling efficiency were studied, including the molecular weight of the initial PBd-t-N3, arm numbers and the molar ratio of the azido group to the alkynyl group. The results indicated that the conversion of the target products would be promoted when the molecular weight of the PBd-t-N3 was low and the molar ratio of the azido to alkynyl groups was close to 1.

Effects of Branches on the Crystallization Kinetics of Polypropylene-gPolystyrene and Polypropylene-g-Poly(n-butyl acrylate) Graft Copolymers with Well-defined Molecular Structures

Effects of branches on the crystallization kinetics of polypropylene-g-polystyrene （PP-g-PS） and polypropylene-g- poly（n-butyl acrylate） （PP-g-PnBA） graft copolymers with well-defined molecular structures were systematically investigated by DSC. The Avrami equation was used to analyze the isothermal crystallization process, while the analysis of nonisothermal crystallization process was based on the Jeziorny-modified Avrami model and Mo model. The kinetics results of isothermal and nonisothermal crystallization verified the peculiar effects of branches on the crystallization process of PP backbones in PP-g-PS and PP-g-PnBA graft copolymers： on one hand, the interaction between branches （n-n interaction between PS branches, or dipole-dipole interaction between PnBA branches） restrained the mobility and reptation ability of the PP backbones, which hindered the crystallization process; on the other hand, the heterogeneous nucleation effect resulting from the branched structure and fluctuation-assisted nucleation mechanism （caused by microphase separation between the PS or PnBA rich phase and the PP rich phase） became more pronounced with increasing branch length, which facilitated the crystallization process.

Random Binary Brush Architecture Enhances both Ionic Conductivity and Mechanical Strength at Room Temperature

The ionic conductivity and the mechanical strength are two key factors for the performance of poly（ethylene oxide）（PEO） based polyelectrolytes. However, crystallized PEO suppresses ion conductivity at low temperature and melted PEO has low mechanical strength at high temperature. Here, random binary brush copolymer composed of PEO-and polystyrene（PS）-based side chains is synthesized. PEO crystallinity is suppressed by the introduction of PS brushes. Doping with lithium trifluoromethanesulfonate（Li Tf） induces microphase separation. Due to a random arrangement of the brushes, the microphase segregation is incomplete even at high salt loading, which provides both high ionic conductivity and high mechanical strength at room temperature. These results provide opportunities for the design of polymeric electrolytes to be used at room temperature.