Mo改性Pd/NaY催化剂用于甲醇间接氧化羰基化合成碳酸二甲酯

碳酸二甲酯(DMC)因具有较好的溶解性、生物降解性和低毒性,而被认为是一种绿色化学品.其用途广泛,不仅用于合成聚碳酸酯,还是锂离子电池电解液、燃料添加剂以及羰基化和甲基化反应的重要试剂.在众多合成方法中,CH_(3)OH间接氧化羰基化合成DMC,具有无爆炸风险、反应条件温和以及原子经济性高等优点,因而展现出广阔的应用前景.然而,这一过程中使用的无氯Pd/NaY催化剂存在以下问题:Pd2+活性物种容易被反应物CO还原成Pd0物种,导致Pd烧结和催化剂失活.因此,如何在催化过程中保持Pd2+物种的稳定,是当前面临的一个重要挑战.本文采用“自上而下”的方法,制备了Mo改性的Pd/NaY催化剂(Pd-Mo/NaY).该催化剂在保持贵金属Pd氧化态的同时,增强了对反应物CO的吸附能力,进而提高了催化剂的稳定性.在CH_(3)OH间接氧化羰基化制DMC反应中,Pd-Mo/NaY表现出比Pd/NaY催化剂更高的催化活性和稳定性.在30 h的反应过程中,Pd-Mo/NaY催化剂上的CO转化率稳定维持在约97%,而Pd/NaY催化剂上的CO转化率则从94%逐渐下降至70%.此外,Pd-Mo/NaY催化剂的本征活性(TOF)为0.019 s^(-1),也明显高于Pd/NaY催化剂的0.005 s^(-1).X射线衍射、物理吸附和扫描电镜结果表明,Mo改性未显著改变Pd/NaY的物相结构、孔结构性质与微观形貌.透射电镜与扫描电镜能谱结果表明,两个催化剂的Pd聚集状态存在显著差异.Pd/NaY催化剂中Pd物种发生了明显聚集,Pd颗粒平均尺寸达到10.2 nm;而Pd-Mo/NaY催化剂中,大部分Pd物种仍保持高度分散的状态,仅有少量聚集的Pd颗粒,其平均尺寸仅为2.3 nm.通过羟基红外、吡啶红外与氨气程序升温脱附表征技术进一步研究了催化性能与Pd聚集状态差异的原因.结果表明,Mo的引入有效减少了因Pd离子交换过程引入的桥式羟基,从而降低了Pd-Mo/NaY催化剂的酸性.此外,氢气程序升温还原与X射线光电子能谱结果进一步揭示,Pd与Mo之间的相互作用调变了Pd-Mo/NaY的活性位结构,阻碍了活性Pd^(2+)物种被反应物CO还原为Pd0物种,从而有效缓解了Pd物种的聚集.CO漫反射红外与CO低温透射红外研究则表明,Pd-Mo之间的相互作用以及Pd2+活性位点的增加,显著增强了催化剂对反应物CO的吸附能力.通过原位漫反射红外(DRIFTS)实验捕获了COOCH_(3)*关键反应中间体,并发现无论是Pd/NaY催化剂还是Mo改性的Pd-Mo/NaY催化剂,均遵循相似的反应路径,并具有相同的决速步骤.综上,本文通过Mo对Pd/NaY催化剂进行改性,有效抑制了反应过程中贵金属Pd的烧结,从而显著提高Pd-Mo/NaY催化剂的稳定性.通过这一改性方法,实现了活性Pd2+物种的高度稳定,为甲醇间接氧化羰基化制DMC催化剂的研发提供了新思路.

西北地区涉核企业核安全文化评估分析及改进措施研究

本文简要阐述了西北地区生态环境部直管单位的核安全文化评估现状,系统地总结了生态环境部西北核与辐射安全监督站(以下简称西北监督站)以核安全文化评估为抓手,积极探索西北地区的生态环境部直管单位的新型监督方式、西北地区生态环境部直管单位核安全文化建设中存在的优缺点,针对西北地区核安全文化评估中存在的问题进行了初步总结。

地质雷达在城市活动断层探测中的应用——以鹤壁市汤东断裂为例

城市地区人口密集、经济发达,发生在城市之下的大地震是对城市危害最大的突发性自然灾害,会造成巨大的生命财产损失,并引发一系列社会安全问题。位于城市之下的活动断层是造成城市地震灾害的元凶,地震发生时活动断层沿线也是建筑物破坏最严重、造成人员伤亡最集中的地带,例如1906年旧金山8.1级地震,1999年集集7.6级地震。

基于知识图谱的配电网综合评价

为方便工作人员学习和掌握配电网综合评价知识,能够全方位感知配电网运行状况,将传统配电网综合评价方法与具有互联性、开放性、结构化和形象化刻画知识的知识图谱技术相结合,提出了一种基于知识图谱的配电网综合评价方法。首先采用自顶向下和自底向上相结合的图谱构建方式,从模式层和数据层2方面构建图谱,并将其分为配电网实体图谱、评价逻辑图谱和案例图谱。其次,分析核心构建技术,知识推理技术,并结合实际评价场景,为评价流程各环节的实现提供思路。最后基于上述方法,展示实际评价案例中的评价逻辑图谱,验证了所述方法的可行性。

浅层人工地震和地质雷达在城市活动断层探测中的联合应用--以鹤壁市汤东断裂为例

浅层人工地震勘探是探查城市隐伏活动断层最有效的手段之一,然而受近地表探测盲区和探测分辨率的限制,该方法难以获取活动断层超浅层上断点的准确埋深位置。地质雷达探测方法在一定程度上可弥补浅层人工地震勘探的不足。为探索浅层人工地震勘探和地质雷达探测的联合应用效果,分析其在城市隐伏活动断层探测中的应用潜力,选取河南省鹤壁市汤东断裂西支为研究对象,并在冯屯村和前交卸村分别开展联合探测,获取高信噪比的浅层人工地震反射剖面和地质雷达剖面。浅层人工地震勘探揭示的冯屯村处汤东断裂西支上断点埋深为60~70 m,地质雷达探测揭示的上断点埋深约为2.5 m,结合平均沉积速率推测汤东断裂西支在冯屯村的最新活动时代约为25 ka。浅层人工地震勘探揭示的前交卸村处汤东断裂西支上断点埋深为50~60 m,地质雷达探测揭示出汤东断裂西支在前交卸村处未造成近地表约10 m以内的地层断错。研究结果表明,在城市隐伏活动断层探测中,采用浅层人工地震勘探和地质雷达探测相结合的方法,不但可有效确定活动断层的位置,且可进一步约束活动断层上断点的准确埋深,有利于指导后期地震地质勘探中的探槽和钻孔布设。

Statistical analysis of mesoscale eddy propagation velocity in the South China Sea deep basin

Using mesoscale eddy trajectory product derived from satellite altimetry data from 1993 to 2017,this study analyzes the statistical characteristics of spatiotemporal distribution of mesoscale eddy propagation velocities(C)in the South China Sea(SCS)deep basin with depths>1000 m.Climatologically,the zonal propagation velocities(cx)are westwards in the whole basin,and the meridional velocities(cy)are southwards in the northwestern basin,and northwards in the southeastern basin.The variation of cy with longitude is consistent with that of the background meridional currents with correlation coefficient R2 of 0.96,while the variation of cx is related both to the background zonal currents andβeffect.The propagation velocities characterize significant seasonality with the minimum magnitude occurring in summer and the maximum in winter for cx and C.Interannually,larger values of cx and cy mostly occurred in La Ni?a years in the negative phase of the Pacific Decadal Oscillation(PDO).Mesoscale eddies move fast at the beginning and end of their life span,i.e.,at their growth and dissipation periods,and slowly during their stable"midlife"period.This trend is negatively correlated with the rotating tangential velocity with R2 of–0.93.Eddies with extreme propagation velocities are defined,which are slower(faster)than 1.5 cm/s(15.4 cm/s)and take 1.5%(1.9%)of the total eddies.The extremely slow-moving(fastmoving)eddies tend to appear in the middle(on the edge)of the basin,and mostly occur in summer(winter).The mechanism analysis reveals that the spatiotemporal distributions of the propagation velocities of mesoscale eddies in the SCS are modulated by the basin-scale background circulation.

Genetic diversity assessment of a set of introduced mung bean accessions(Vigna radiata L.)

Genetic resources from other countries or regions play an important role in broadening the genetic background of local breeding varieties. Here we describe observations on the adaptability of mung bean germplasm obtained from the United States Department of Agriculture and their genetic diversity assessment using SSR markers. Several accessions were shown to be mixtures,based on their phenotypes for some characters. Most accessions were able to complete their lifecycles when grown in Beijing, China, making them ideal for crossbreeding without day length control. High diversity was revealed by the SSR markers, with an average of 4.2 alleles per locus and a PIC value of 0.650 per locus. STRUCTURE analysis divided the accessions into six groups.There was no obvious trend of accessions forming groups according to their geographical origin,owing mainly to germplasm exchange and an uneven distribution of accessions. The present results indicate that this germplasm would enrich the local gene pool, and provide information for the further use of germplasm in breeding programs.

Targeted transfer of self-assembled CdSe nanoplatelet film onto WS_(2) flakes to construct hybrid heterostructures

Colloidal CdSe nanoplatelets are thin semiconductor materials with atomic flatness surfaces and one-dimensional strong quantum confinement,and hence they own very narrow and anisotropic emission.Here,we present a polydimethylsiloxane(PDMS)assisted transferring method that can pick up single layer CdSe nanoplatelet films self-assembled on a liquid surface and then precisely transfer to a target.By layer-by-layer picking up and transferring,multiple layers of CdSe films can be built up to form CdSe stacks with each single layer having dominant in-plane transition dipole distribution,which both material and energic structures are analogous to traditional multiple quantum wells grown by molecular-beam epitaxy.Additionally,with the great flexibility of colloidal nanoplatelets and this transferring method,CdSe nanoplatelets films can be combined with other materials to form hybrid heterostructures.We transferred a single-layer CdSe film onto WS_(2) flakes,and precisely studied the fast energy transfer rate with controlled CdSe nanoplatelet orientation and by using a streak camera with a ps time resolution.

Effects of wave-current interaction on the waves, cold-water mass and transport of diluted water in the Beibu Gulf

Wave-current interaction and its effects on the hydrodynamic environment in the Beibu Gulf(BG) have been investigated via employing the Coupled Ocean–Atmosphere–Wave–Sediment Transport(COAWST) modeling system. The model could simulate reasonable hydrodynamics in the BG when validated by various observations.Vigorous tidal currents refract the waves efficiently and make the seas off the west coast of Hainan Island be the hot spot where currents modulate the significant wave height dramatically. During summer, wave-enhanced bottom stress could weaken the near-shore component of the gulf-scale cyclonic-circulation in the BG remarkably, inducing two major corresponding adjustments: Model results reveal that the deep-layer cold water from the southern BG makes critical contribution to maintaining the cold-water mass in the northern BG Basin.However, the weakened background circulation leads to less cold water transported from the southern gulf to the northern gulf, which finally triggers a 0.2℃ warming in the cold-water mass area;In the top areas of the BG, the suppressed background circulation reduces the transport of the diluted water to the central gulf. Therefore, more freshwater could be trapped locally, which then triggers lower sea surface salinity(SSS) in the near-field and higher SSS in the far-field.

Application of Endoscopic Vein Harvesting in Obese Patients Undergoing Coronary Artery Bypass Grafting

This study aims to evaluate the clinical outcomes of endoscopic vein harvesting （EVH） for coronary artery bypass grafting （CABG） in obese patients. Totally, 153 obese patients who underwent EVH （n=81） or standard bridging technique （SBT, n=72） in CABG surgery from May 2012 to October 2014 in our hospital were enrolled in this retrospective non-randomized controlled study. The general situation of operation, postoperative complications and short medium-term outcomes were analyzed. The baseline characteristics were similar between these two groups （P〉0.05）. There were no statistical differences in total operation time （226±28 min vs. 224±30 min, P〉0.05）, number of damaged vessels （0.12±0.05 vs. 0.16±0.06, P〉0.05） and short medium-term outcomes including revascularization rate （1.25% vs. 2.78%, P〉0.05）, vessel dysfunction rate （11.25% vs. 11.11%, P〉0.05） and mortality （0.00% vs. 0.00%, P〉0.05）. Use of EVH was associated with significant reduction of total harvesting time （41±6 min vs. 63±11 min, P〈0.05）, incision length （4.4±1.1 cm vs. 18.2±4.5 cm, P〈0.05） and postoperative lower extremity complications （P〈0.05）. EVH can reduce the risk of wound complications, whereas does not influence short- and medium-term outcomes in obese patients. It can be considered a reliable procedure of harvesting vessel conduits for obese patients undergoing CABG.

Role of Interleukin 17A in Aortic Valve Inflammation in Apolipoprotein E-deficient Mice

Summary:Interleukin 17A(IL 17A)is reported to be involved in many inflammatory processes,but its role in aortic valve diseases remains unknown.We examined the role of IL17A based on an ApoE^-/-mouse model with strategies as fed with high-fat diet or treated with ILI7A monoclonal antibody(mAb).12 weeks of high-fat diet feeding can elevate cytokines secretion,inflammatory cells infiltration and myofibroblastic transition of valvular interstitial cells(VICs)in aortic valve.Moreover,diet-induction accelerated interleukin 17 receptor A(IL17RA)activation in VICs.In an IL17A inhibition model,the treatment group was intra-peritoneally injected with anti-IL17A mAb while controls received irrelevant antibody.Functional blockade of IL17A markedly reduced cellular infiltration and transition in aortic valve.To investigate potential mechanisms,NF-kB was co-stained in IL17RA^+VICs and IL17RA macrophages,and further confirmed by Western blotting in VICs.High-fat diet could activate NF-kB nuclear translocation in IL17RA^+VICs and IL17RA^+macrophages and this process was depressed after IL17A mAb-treatment.In conclusion,high-fat diet can lead to IL17A upregulation,VICs myofibroblastic transition and inflammatory cells infiltration in the aortic value of ApoE^-/-mice.Blocking IL17A with IL17A mAb can alleviate aortic valve inflammatory states.

Characterization and Performance Evaluation of Turbulent Plasma Sheath Channel

Radio waves are highly attenuated and distorted by turbulent plasma sheath around hypersonic vehicles in near space, leading to communication blackout. The purpose of the paper is to investigate the plasma channel characteristics and the communication performances over the channel. We treat the turbulent plasma medium as a fast fading wireless channel. The coherence time and the spectrum spread of the plasma sheath channel are obtained in terms of root-meansquare(RMS). Baseband simulation scheme is proposed based on a stratified model of the plasma flow field. Results indicate that the coherence time is on the order of milliseconds and decreases rapidly with the increasing electron density turbulence. The spectrum spread due to plasma turbulence is also significant. Extensive simulations have been carried out to make communication performance evaluations. Quantitative results show that error floor takes place for PSK and QAM, while FSK with noncoherent detection is a promising method to mitigate the blackout problem.

Effects of tidal currents on winter wind waves in the Qiongzhou Strait:a numerical study

Effects of currents on winter wind waves in the tide-dominated Qiongzhou Strait(QS)were numerically evaluated via employing the coupled ocean-atmosphere-wave-sediment transport(COAWST)modeling system.Validations showed satisfactory model performance in simulating the intense tidal currents in the QS.Different effects of sea level variations and tidal currents on waves were examined under the maximum eastward(METC)and westward(MWTC)tidal currents.In the east entrance area of the QS,the positive sea levels under the MWTC deepened the water depth felt by waves,benefiting the further propagation of wave energy into the inner strait and causing increased wave height.The METC and the MWTC could both enhance the wave height in the east entrance area of the QS,mainly through current-induced convergence and wavenumber shift,respectively.By current-induced refraction,the METC(MWTC)triggered counterclockwise(clockwise)rotation in peak wave directions in the northern part of the QS while clockwise(counterclockwise)rotation in the southern part.

基于Kafka集群的物联微服务数据接入模式的研究

采用传统数据接入模式处理物联网中存在的海量数据信息,其扩展性较差,难以切换写入的实时数据,导致物联网平台切换时延过高。文中提出基于Kafka集群的物联微服务数据接入模式,根据用户位置、物联微服务数据量以及处理时间,设置物联微服务数据频繁接入模式;采用基于Kafka集群分布式的信息处理方式,设置数据接入模式。仿真结果表明:设计的数据接入模式在进行数据接入时,其数据所占空间较小,且数据接入后切换时延较短,可为复杂的物联微服务数据提供更加高效的接入模式。

Upwelling off the west coast of Hainan Island: sensitivity to wave-mixing

The coupled ocean atmosphere wave sediment transport(COAWST)modeling system is employed to investigate the role of wave-mixing playing in the upwelling off the west coast of Hainan Island(WHU).Waves,tides and sea surface temperature(SST)are reproduced reasonably well by the model when validated by observations.Model results suggest the WHU is tidally driven.Further investigations indicate that inclusion of wave-mixing promotes the intensity of the WHU,making the simulated SST become more consistent with remote-sensed ones.Dynamically,wave-mixing facilitates the“outcrop”of more upwelled cold water,triggering stronger WHU and leading to a three-dimensional dynamical adjustment.From the perspective of time,wave-mixing contributes to establishing an earlier tidal mixing front strong enough to generate WHU and that is,WHU may occur earlier when taking wave-mixing into consideration.

Response of runoff and its components to climate change in the Manas River of the Tian Shan Mountains

A warming-wetting climate trend has led to increased runoff in most watersheds in the Tian Shan Mountains over the past few decades.However,it remains unclear how runoff components,that is,rainfall runoff(Rrain),snowmelt runoff(Rsnow),and glacier meltwater(Rglacier),responded to historical climate change and how they will evolve under future climate change scenarios.Here,we used a modified Hydrologiska Byrans Vattenbalansavdelning(HBV)model and a detrending method to quantify the impact of precipitation and temperature changes on runoff components in the largest river(Manas River)on the northern slope of the Tian Shan Mountains from 1982 to 2015.A multivariate calibration strategy,including snow cover,glacier area,and runoff was implemented to constrain model parameters associated with runoff components.The downscaled outputs of 12 general circulation models(GCMs)from the Sixth Coupled Model Intercomparison Project(CMIP6)were also used to force the modified HBV model to project the response of runoff and its components to future(2016-2100)climate change under three common socio-economic pathways(SSP126,SSP245,and SSP585).The results indicate that Rrain dominates mean annual runoff with a proportion of 42%,followed by Rsnow(37%)and Rglacier(21%).In terms of inter-annual variation,Rrain and Rsnow show increasing trends(0.93(p<0.05)and 0.31(p>0.05)mm per year),while Rglacier exhibits an insignificant(p>0.05)decreasing trend(-0.12 mm per year),leading to an increasing trend in total runoff(1.12 mm per year,p>0.05).The attribution analysis indicates that changes in precipitation and temperature contribute 8.16 and 10.37 mm,respectively,to the increase in runoff at the mean annual scale.Climate wetting(increased precipitation)increases Rrain(5.03 mm)and Rsnow(3.19 mm)but has a limited effect on Rglacier(-0.06 mm),while warming increases Rrain(10.69 mm)and Rglacier(5.79 mm)but decreases Rsnow(-6.12 mm).The negative effect of glacier shrinkage on Rglacier has outweighed the positive effect of warming on Rglaciers resulting in the tipping point(peak water)for Rglacier having passed.Runoff projections indicate that future decreases in Rglacier and Rsnow could be offset by increases in Rrain due to increased precipitation projections,reducing the risk of shortages of available water resources.However,management authorities still need to develop adequate adaptation strategies to cope with the continuing decline in Rgacier in the future,considering the large inter-annual fluctuations and high uncertainty in precipitation projection.

颈部七线调衡疗法探析并病例汇报一例

脑卒中是威胁全球居民生命健康的重大疾病之一。脑卒中以其高发病率、高致残率、高病死率及高复发率成为国民健康的重大威胁。“颈椎病变与缺血性脑血管病相关学说”提出颈椎病变可能通过影响椎基底动脉系统导致脑供血不足,引发脑卒中。颈项部是气血流通的关键,是脑与躯干四肢连接的枢纽和沟通的桥梁,很多疾病发生、进展与颈项部气血失和相关,本研究课题组在传统中医经络循行理论的基础上,结合颈项部解剖学特点,依据骨性标志定位法创新性提出颈部七线调衡疗法。颈部七线调衡疗法可改善脑供血、安神补髓、调衡项背部经络平衡、松筋理结止痛,组方简洁、规整,操作简便,安全性高,在脑卒中的预防和慢病管理方面具有一定的应用价值。

无模板插层-剥离勃姆石合成具有优异稳定性的多孔硅掺杂氧化铝二维纳米片

高比表面积和大孔容的多孔氧化铝已被广泛应用在各种领域,但不使用有机模板合成多孔氧化铝仍面临巨大挑战.在此,我们报道了基于插层-剥离策略的多孔氧化铝合成方法,利用硅物种削弱勃姆石(氧化铝前体)的层间作用力,从而在不使用有机模板的情况下将勃姆石剥离成二维纳米片.该合成过程可放大到3 L,并获得厚度为2 nm的二维纳米片.此外,这些二维纳米片可组装成比表面为542 m^(2)g^(-1)和孔容为2.43 cm^(3)g^(-1)的勃姆石.在不同温度下对二维纳米片进行热/水热处理得到的多孔氧化铝其孔结构优于多数有机模板法合成的氧化铝,并表现出优异的吸附性能.本研究为合成二维勃姆石纳米片和多孔氧化铝材料提供了一种新策略.

b轴取向MFI型分子筛膜二次生长合成策略及其应用

b轴取向MFI型分子筛膜因其在膜分离、膜催化反应器研究领域的重要应用引起了广泛关注。本文综述了二次生长法合成b轴MFI型分子筛膜的最新研究进展,从晶种的合成、晶种涂覆方式以及二次生长溶液的组成等方面详细总结了调控b取向MFI型分子筛膜合成的方法;比较了不同分子筛膜合成策略的优缺点,及这些合成策略对不同体系的分离效果(分离因子与通量)和催化性能的影响。本文还介绍了近年来二维(2D)分子筛和分子筛纳米片的监测与生长控制方法,自下而上直接合成纳米片与高通量、高选择性分子筛膜合成方面的最新突破。通过深入探讨各种分子筛膜制备策略,对b轴取向分子筛膜制备的发展趋势进行了展望。

共生菌通过氧气浓度调控果蝇产卵偏嗜性

【目的】研究东方醋杆菌(Acetobacter orientalis)和短小乳杆菌(Lactobacillus brevis)通过氧气浓度调控黑腹果蝇(Drosophila melanogaster)产卵的偏嗜性,并研究其对后代存活率和发育历期的生物学意义。【方法】利用双相选择装置解析果蝇产卵行为。利用分光光度仪和pH计测量细菌的OD值与pH值。通过改变果蝇的视觉、味觉和嗅觉感官以检测介导果蝇产卵行为的感觉系统。用后代的发育历期与存活率评价其生物学意义。【结果】果蝇产卵对东方醋杆菌具有趋避性,产卵指数为–0.76,对短小乳杆菌具有趋向性,产卵指数为0.5,并且二者接种比例决定了果蝇的产卵选择。氧气作为一个调节因子,可改变果蝇对东方醋杆菌和短小乳杆菌的产卵偏嗜性。氧气是东方醋杆菌生长必需的条件,有氧培养的OD值为1.3,而无氧培养的OD值为0.4。氧气是短小乳杆菌生长非必需的条件,有氧和无氧培养的OD值均为2.2。破坏嗅觉可严重地影响果蝇对细菌的产卵偏嗜性。东方醋杆菌和短小乳杆菌均促进了果蝇的生长,分别提高存活率1倍和1.5倍,分别缩短果蝇发育历期1 d和2 d。【结论】东方醋杆菌和短小乳杆菌可影响果蝇产卵偏嗜性,并且二者比例决定了果蝇的最终产卵选择。东方醋杆菌和短小乳杆菌通过感知氧气浓度的改变而进行不同的代谢方式,从而进一步调节果蝇产卵选择。嗅觉系统介导果蝇对东方醋杆菌和短小乳杆菌的产卵选择行为,从而提高后代存活率和缩短发育时间。