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Multidimensional compound Poisson distributions in free probability
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作者 Guimei An Mingchu Gao 《中国科学:数学英文版》 SCIE CSCD 2019年第5期921-934,共14页
Inspired by Speicher’s multidimensional free central limit theorem and semicircle families, we prove an in?nite dimensional compound Poisson limit theorem in free probability, and de?ne in?nite dimensional compound f... Inspired by Speicher’s multidimensional free central limit theorem and semicircle families, we prove an in?nite dimensional compound Poisson limit theorem in free probability, and de?ne in?nite dimensional compound free Poisson distributions in a non-commutative probability space. In?nite dimensional free in?nitely divisible distributions are de?ned and characterized in terms of their free cumulants. It is proved that for a sequence of random variables, the following three statements are equivalent:(1) the distribution of the sequence is multidimensional free in?nitely divisible;(2) the sequence is the limit in distribution of a sequence of triangular trays of families of random variables;(3) the sequence has the same distribution as that of {a1(i): i = 1, 2,...}of a multidimensional free L′evy process {{a1(i): i = 1, 2,...} : t≥0}. Under certain technical assumptions, this is the case if and only if the sequence is the limit in distribution of a sequence of sequences of random variables having multidimensional compound free Poisson distributions. 展开更多
关键词 free PROBABILITY MULTIDIMENSIONAL free POISSON DISTRIBUTIONS MULTIDIMENSIONAL free INFINITELY divisible DISTRIBUTIONS
利用Free Video to JPG Converter软件探究弹簧振子的运动
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作者 胡瀚玮 张洪明 林耕波 《湖南中学物理》 2019年第4期75-76,共2页
本文利用Free Video to JPG Converter软件能将视频自动截图的功能,结合Excel软件分析数据,再加上合理外推得到弹簧振子的位移时间图像是一条正弦曲线。
关键词 Free VIDEO to JPG Converter软件 弹簧振子 正弦曲线
Effects of hurricane forward speed and approach angle on storm surges:an idealized numerical experiment 预览
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作者 Chenguang Zhang Chunyan Li 《海洋学报:英文版》 SCIE CAS CSCD 2019年第7期48-56,共9页
The effects of hurricane forward speed(V)and approach angle(θ)on storm surge are important and a systematic investigation covering possible and continuous ranges of these parameters has not been done before.Here we p... The effects of hurricane forward speed(V)and approach angle(θ)on storm surge are important and a systematic investigation covering possible and continuous ranges of these parameters has not been done before.Here we present such a study with a numerical experiment using the Finite Volume Community Ocean Model(FVCOM).The hurricane track is simplified as a straight line,such that V andθfully define the motion of the hurricane.The maximum surge is contributed by both free waves and a forced storm surge wave moving with the hurricane.Among the free waves,Kelvin-type waves can only propagate in the down-coast direction.Simulations show that those waves can only have a significant positive storm surge when the hurricane velocity has a down-coast component.The optimal values of V andθthat maximize the storm surge in an idealized semi-circular ocean basin are functions of the bathymetry.For a constant bathymetry,the maximum surge occurs when the hurricane approaches the coast from the normal direction when the free wave generation is minimal;for a stepped bathymetry,the maximum surge occurs at a certain acute approach angle which maximizes the duration of persistent wind forcing;a step-like bathymetry with a sloped shelf is similar to the stepped bathymetry,with the added possibility of landfall resonance when the free and forced waves are moving at about the same velocity.For other cases,the storm surge is smaller,given other parameters(hurricane size,maximum wind speed,etc.)unchanged. 展开更多
关键词 storm SURGE experiments FVCOM HURRICANE forward speed APPROACH ANGLE KELVIN waves forced and free SURGE interactions
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Unsteady Liquid Film Flow with a Prescribed Free-Surface Velocity
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作者 方铁钢 王甫军 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第1期36-39,共4页
A liquid film flow over a flat plate is investigated by prescribing the unsteady interface velocity.With this prescribed surface velocity,the governing Navier-Stokes (NS)equations are transformed into a similarity ord... A liquid film flow over a flat plate is investigated by prescribing the unsteady interface velocity.With this prescribed surface velocity,the governing Navier-Stokes (NS)equations are transformed into a similarity ordinary differential equation,which is solved numerically.The flow characteristics is controlled by an unsteadiness parameter S and the flow direction parameter Λ.The results show that solutions only exist for a certain range of the unsteadiness parameter,i.e.,S≤1 for Λ=-1 and S≤-2.815877 for Λ=1.In the solution domain, the dimensionless liquid film thickness β decreases with S for both the cases.The wall shear stress increases with the decrease of S for Λ=-1.However,for Λ=-1 the shear stress magnitude first decreases and then increases with the decrease of S.There are no zero erossing points for the velocity profiles for both the cases.The profiles of velocity stay either positive or negative all the time,except for the wall zero velocity.Consequently, the vertical velocity becomes a monotonic function.To maintain the prescribed velocity,mass transpiration is generally needed,but for the shrinking film case it is possible to have an impermeable wall.The results are also an exact solution to the furl NS equations. 展开更多
关键词 Free surface VELOCITY UNSTEADY liquid FILM The governing EQUATION
A New Milestone
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作者 He Wenping 《中国与非洲:英文版》 2019年第7期10-11,共2页
The African Continental Free Trade Area (AfCFTA) agreement took effect on May 30. It is expected that the free trade area will be officially launched on July 7. As of the end of May, 52 out of the 55 African Union (AU... The African Continental Free Trade Area (AfCFTA) agreement took effect on May 30. It is expected that the free trade area will be officially launched on July 7. As of the end of May, 52 out of the 55 African Union (AU) members have signed the agreement, except for Nigeria, Eritrea and Benin. According to the AU, when all of its 55 members sign up, the AfCFTA will be the world s largest free trade area in terms of membership since the founding of the World Trade Organization, and will be a huge market covering 1.2 billion people and a collective GDP of $2.5 trillion. 展开更多
关键词 AfCFTA Free TRADE
Planar Cubic G1 Hermite Interpolant with Minimal Quadratic Oscillation in Average 预览
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作者 Li Jun-cheng 《数学研究通讯:英文版》 CSCD 2019年第3期219-224,共6页
In this paper we apply a new method to choose suitable free parameters of the planar cubic G1 Hermite interpolant. The method provides the cubic G1 Hermite interpolant with minimal quadratic oscillation in average. We... In this paper we apply a new method to choose suitable free parameters of the planar cubic G1 Hermite interpolant. The method provides the cubic G1 Hermite interpolant with minimal quadratic oscillation in average. We can use the method to construct the optimal shape-preserving interpolant. Some numerical examples are presented to illustrate the effectiveness of the method. 展开更多
关键词 CUBIC HERMITE interpolant free parameter optimization shape-preserving interpolant
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Charge-state populations for the neon-XFEL system
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作者 邓萍 蒋刚 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第6期155-163,共9页
The interaction between neon and x-ray free-electron lasers with different laser parameters is systematically studied by solving a set of coupled rate equations. As an example, the evolution of 1s~12 s~22 p~6 configur... The interaction between neon and x-ray free-electron lasers with different laser parameters is systematically studied by solving a set of coupled rate equations. As an example, the evolution of 1s~12 s~22 p~6 configuration is given under different incident photon numbers, pulse widths, and photon energies. We have also determined all of the charge-state populations as a function of three laser pulse parameters by averaging over time. The result shows that the variations of these charge-state populations demonstrate a pattern when the pulse width is shorter than 10 fs: some of the charge-states decrease rapidly,while the others rise but remain relatively constant for pulse width larger than 10 fs. The variation of the average charge with three parameters has also obtained. The average charge decreases for a pulse width shorter than 10 fs but remains basically unchanged for a pulse width longer than 10 fs. 展开更多
关键词 x-ray free electron LASERS NEON CHARGE-STATE population pulse WIDTH
Axial magnetic field effect in numerical analysis of high power Cherenkov free electron laser
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作者 F BazoubAND B Maraghechi 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第6期176-183,共8页
Cherenkov free electron laser(CFEL) is simulated numerically by using the single particle method to optimize the electron beam. The electron beam is assumed to be moving near the surface of a flat dielectric slab alon... Cherenkov free electron laser(CFEL) is simulated numerically by using the single particle method to optimize the electron beam. The electron beam is assumed to be moving near the surface of a flat dielectric slab along a growing radiation. The set of coupled nonlinear differential equations of motion is solved to study the electron dynamics. For three sets of parameters, in high power CFEL, it is found that an axial magnetic field is always necessary to keep the electron beam in the interaction region and its optimal strength is reported for each case. At the injection point, the electron beam’s distance above the dielectric surface is kept at a minimum value so that the electrons neither hit the dielectric nor move away from it to the weaker radiation fields and out of the interaction region. The optimal electron beam radius and current are thereby calculated. This analysis is in agreement with two previous numerical studies for a cylindrical waveguide but is at odds with analytical treatments of a flat dielectric that does not use an axial magnetic field. This is backed by an interesting physical reasoning. 展开更多
关键词 CHERENKOV free ELECTRON laser AXIAL magnetic field flat dielectric SLAB ELECTRON beam
论《儒林外史》中的反抗实践及其可能 预览
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作者 路文彬 《枣庄学院学报》 2019年第4期61-70,共10页
《儒林外史》是中国文学史上第一部拥有自觉反抗意识的作品,反抗本身即意味着某种个体意识的觉醒。但反抗的指归不是破坏和说不,乃是恢复和说是。《儒林外史》中人物之于现世权力的反抗实质上就是之于古礼的服从,只是由于这种古礼往往... 《儒林外史》是中国文学史上第一部拥有自觉反抗意识的作品,反抗本身即意味着某种个体意识的觉醒。但反抗的指归不是破坏和说不,乃是恢复和说是。《儒林外史》中人物之于现世权力的反抗实质上就是之于古礼的服从,只是由于这种古礼往往拘于外在规则,因而无法落实为主体的内在美德,导致他们的反抗试图恢复的并非真正的自由,结果等待他们的就不可能是成功。 展开更多
关键词 《儒林外史》 反抗 自由
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Unexpected activated carbon-catalyzed pyrrolo[1,2-a]quinoxalines synthesis in water
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作者 Qi Sun Liyan Liu +2 位作者 Yu Yang Zhenggen Zha Zhiyong Wang 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第7期1379-1382,共4页
An interesting and recyclable activated carbon/water catalytic system for efficient synthesis of pyrrolo[1,2-a]quinoxaline derivatives was developed. The intramolecular C-N and C-C bond can be easily constructed in wa... An interesting and recyclable activated carbon/water catalytic system for efficient synthesis of pyrrolo[1,2-a]quinoxaline derivatives was developed. The intramolecular C-N and C-C bond can be easily constructed in water under mild condition. This reaction features a broad substrate scope, a good tolerance to water and air, metal-free, additive-free and redox reagent-free. 展开更多
关键词 Pyrrolo[1 2-a]quinoxalines Activated carbon C-C C-N bond-forming Metal free WATER SOLVENT
蚌埠市9888名女性免费婚检结果分析 预览
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作者 张睿 李娜 彭蓉蓉 《淮海医药》 CAS 2019年第4期345-348,共4页
目的:分析蚌埠市2017—2018年免费婚检对象中所有女性受检者9888人的相关资料,探讨蚌埠市女性婚前健康状况,以期提升婚检服务质量和优生优育服务水平。方法:对9888名女性参加免费婚检检出疾病等情况进行统计分析。结果:蚌埠市2017年和2... 目的:分析蚌埠市2017—2018年免费婚检对象中所有女性受检者9888人的相关资料,探讨蚌埠市女性婚前健康状况,以期提升婚检服务质量和优生优育服务水平。方法:对9888名女性参加免费婚检检出疾病等情况进行统计分析。结果:蚌埠市2017年和2018年婚前医学检查率超过80%,9888名女性受检者疾病总检出率为27.78%,前十位分别为:乳腺囊性增生、阴道炎、贫血、乙肝病毒携带、尿路感染、高血压病、心动过速、隐性梅毒、乳房肿瘤、盆腔附件包块;女性婚检HBsAg阳性率为2.87%,2年婚检阳性率比较,差异有统计学意义(P<0.05),呈下降趋势,女性婚检中抗-TP阳性率为0.44%,2年阳性率比较差异无统计学意义(P>0.05),女性受检者抗-HIV阳性检出者2年均为0;参加免费婚检时20.52%女性处于妊娠期,2年婚前妊娠率比较,差异有统计学意义(P<0.05),呈上升趋势。结论:蚌埠市免费婚检对女性影响婚育疾病的检出效果显著,需要继续加大免费婚检宣传力度,使宣教人群年轻化。婚检机构要重视病例讨论和阳性病例的追踪随访,不断提升婚检医师的疾病检出能力和咨询指导水平。 展开更多
关键词 婚前医学检查 免费 女性
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Effect of crystalline structure on terbuthylazine degradation by H2O2-assisted TiO2 photocatalysis under visible irradiation
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作者 Jianjun Tang Yiqing Chen Zijun Dong 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第5期153-160,共8页
Various methods for shifting the optical response of TiO2 into the visible(Vis) range have been reported. Herein, we reported the application of a TiO2/H2O2/Vis process and the effects of TiO2 crystalline structure on... Various methods for shifting the optical response of TiO2 into the visible(Vis) range have been reported. Herein, we reported the application of a TiO2/H2O2/Vis process and the effects of TiO2 crystalline structure on the degradation of terbuthylazine. The results indicated that TiO2 crystalline structure and H2O2 addition had significant effects on terbuthylazine degradation: its degradation rate could be increased from 7% to 70% with H2O2 addition after 180 min of reaction, the synergistic degradation of terbuthylazine by TiO2-Fe3+ was substantially accelerated, with the degradation rate reaching up to 100% after20 min of reaction, and rutile TiO2 showed better photocatalytic activity and a more obvious synergistic effect than anatase TiO2. The addition of free-radical scavengers(tert-butyl alcohol or methanol) inhibited the degradation efficiency of rutile TiO2, but had a relatively minor effect on anatase TiO2. Fluorescence spectrophotometry analysis indicated that hydroxyl free radicals could be continuously produced when using rutile TiO2 as the photocatalyst. Degradation of terbuthylazine catalyzed by rutile TiO2 occurred mainly in solution, but occurred on the particle surface of the photocatalyst when catalyzed by anatase TiO2. This study provides new insight into the role of TiO2 crystalline structure on the degradation of terbuthylazine and its photocatalytic degradation mechanism. 展开更多
关键词 VISIBLE-LIGHT PHOTOCATALYSIS Reaction pathway HYDROXYL free RADICAL Hydrogen PEROXIDE
Exploring atmospheric free-radical chemistry in China:the self-cleansing capacity and the formation of secondary air pollution
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作者 Keding Lu Song Guo +7 位作者 Zhaofeng Tan Haichao Wang Dongjie Shang Yuhan Liu Xin Li Zhijun Wu Min Hu Yuanhang Zhang 《国家科学评论:英文版》 CSCD 2019年第3期579-594,共16页
Since 1971,it has been known that the atmospheric free radicals play a pivotal role in maintaining the oxidizing power of the troposphere.The existence of the oxidizing power is an important feature of the troposphere... Since 1971,it has been known that the atmospheric free radicals play a pivotal role in maintaining the oxidizing power of the troposphere.The existence of the oxidizing power is an important feature of the troposphere to remove primary air pollutants emitted from human beings as well as those from the biosphere.Nevertheless,serious secondary air-pollution incidents can take place due to fast oxidation of the primary pollutants.Elucidating the atmospheric free-radical chemistry is a demanding task in the field of atmospheric chemistry worldwide,which includes two kinds of work:first,the setup of reliable radical detection systems;second,integrated field studies that enable closure studies on the sources and sinks of targeted radicals such as OH and NO3.In this review,we try to review the Chinese efforts to explore the atmospheric free-radical chemistry in such chemical complex environments and the possible link of this fast gas-phase oxidation with the fast formation of secondary air pollution in the city-cluster areas in China. 展开更多
关键词 ATMOSPHERIC CHEMISTRY free RADICALS new particle formations OH NO3
China Champions Multilateralism and Free Trade 预览
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作者 ZHANG HUI 《今日中国:英文版》 2019年第8期22-25,共4页
THE G20 Osaka Summit in Japan convened on June 28-29 had the world hold its breath. Not only were front-burner issues, such as WTO reform and digitalization of the economy, discussed there, but there was much fanfare ... THE G20 Osaka Summit in Japan convened on June 28-29 had the world hold its breath. Not only were front-burner issues, such as WTO reform and digitalization of the economy, discussed there, but there was much fanfare around the first high-level meeting between China and the United States since the last G20 summit in Buenos Aires late last year. Given the mounting trade tensions between the two countries, the meeting took global center stage. 展开更多
关键词 China Champions MULTILATERALISM Free TRADE the ECONOMY
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Differences in pathological changes between two rat models of severe traumatic brain injury 预览
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作者 Yi-Ming Song Yu Qian +6 位作者 Wan-Qiang Su Xuan-Hui Liu Jin-Hao Huang Zhi-Tao Gong Hong-Liang Luo Chuang Gao Rong-Cai Jiang 《中国神经再生研究:英文版》 SCIE CAS CSCD 2019年第10期1796-1804,共9页
The rat high-impact free weight drop model mimics the diffuse axonal injury caused by severe traumatic brain injury in humans,while severe controlled cortical impact can produce a severe traumatic brain injury model u... The rat high-impact free weight drop model mimics the diffuse axonal injury caused by severe traumatic brain injury in humans,while severe controlled cortical impact can produce a severe traumatic brain injury model using precise strike parameters.In this study,we compare the pathological mechanisms and pathological changes between two rat severe brain injury models to identify the similarities and differences.The severe controlled cortical impact model was produced by an electronic controlled cortical impact device,while the severe free weight drop model was produced by dropping a 500 g free weight from a height of 1.8 m through a plastic tube.Body temperature and mortality were recorded,and neurological deficits were assessed with the modified neurological severity score.Brain edema and bloodbrain barrier damage were evaluated by assessing brain water content and Evans blue extravasation.In addition,a cytokine array kit was used to detect inflammatory cytokines.Neuronal apoptosis in the brain and brainstem was quantified by immunofluorescence staining.Both the severe controlled cortical impact and severe free weight drop models exhibited significant neurological impairments and body temperature fluctuations.More severe motor dysfunction was observed in the severe controlled cortical impact model,while more severe cognitive dysfunction was observed in the severe free weight drop model.Brain edema,inflammatory cytokine changes and cortical neuronal apoptosis were more substantial and blood-brain barrier damage was more focal in the severe controlled cortical impact group compared with the severe free weight drop group.The severe free weight drop model presented with more significant apoptosis in the brainstem and diffused blood-brain barrier damage,with higher mortality and lower repeatability compared with the severe controlled cortical impact group.Severe brainstem damage was not found in the severe controlled cortical impact model.These results indicate that the severe controlled cortical impact model is relat 展开更多
关键词 nerve REGENERATION severe traumatic brain INJURY animal model comparison free weight drop controlled cortical impact NEUROLOGICAL impairment NEUROINFLAMMATION blood-brain barrier damage neuronal apoptosis diffuse AXONAL INJURY BRAINSTEM INJURY neural REGENERATION
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A User-friendly Living Cationic Polymerization: Degenerative Chaintransfer Polymerization of Vinyl Ethers by Simply Using Mixtures of Weak and Superstrong Protonic Acids
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作者 Mineto Uchiyama Masataka Sakaguchi +1 位作者 Kotaro Satoh Masami Kamigaito 《高分子科学:英文版》 SCIE CAS CSCD 2019年第9期851-857,共7页
Mixtures of a weak protonic acid and a trace amount of superstrong protonic acid were used for the simple control of the cationic polymerization of vinyl ethers via a degenerative chain-transfer mechanism, in which th... Mixtures of a weak protonic acid and a trace amount of superstrong protonic acid were used for the simple control of the cationic polymerization of vinyl ethers via a degenerative chain-transfer mechanism, in which the former acid works as a precursor of the chain transfer agent (CTA) or the dormant species and the latter works as a source of the cationic propagating species. The addition of mixtures of phosphoric acid dibutyl ester ((n=BuO)2PO2H) or 1 -octanethiol (n-C8H17SH) and a trace amount of trifluoromethanesulfonic acid (TfOH) to a solution of isobutyl vinyl ether (IBVE) at -78℃ resulted in polymers with controlled molecular weights, which were basically determined by the feed ratio of IBVE to the weak protonic acid, and narrow molecular weight distributions (Mw/Mn≈ 1.1). These results were almost the same as those obtained using their prepared adducts of IBVE as CT As in the presence of a trace amount of TfOH under similar conditions. Methanesulfonic acid (CH3SO3H), whose adduct of IBVE has not been isolated due to instability, was similarly used in conjunction with trace TfOH to result in controlled molecular weights but slightly broader MWDs (Mw/Mn = 1.2-1.8). These results indicate that the sulfoxonium ion is also an effective intermediate in the cationic DT polymerization in addition to the phosphonium and sulfonium intermediates derived from (n=BuO)2PO2H and C8H17SH, respectively. The simple living cationic polymerization was thus achieved by using a combination of a weak protonic acid and a trace amount of TfOH, which are both easily available, low cost, free from metal, and easy to handle, without need for preparation of the initiator. 展开更多
关键词 Living CATIONIC POLYMERIZATION DEGENERATIVE chain transfer RAFT POLYMERIZATION Metal free VINYL ETHER
An Electrochemical Cinnamyl C—H Amination Reaction Using Carbonyl Sulfamate
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作者 Shuai Liu Jin Li +5 位作者 Dalin Wang Feng Liu Xu Liu Yongyuan Gao Dai Jie Xu Cheng 《中国化学:英文版》 SCIE CAS CSCD 2019年第6期570-574,共5页
An electrochemical cinnamyl C—H amination reaction in the absence of transition metal catalyst and oxidant was reported. The choice of carbonyl sulfamate as nitrogen source is the key to achieve desired chemoselectiv... An electrochemical cinnamyl C—H amination reaction in the absence of transition metal catalyst and oxidant was reported. The choice of carbonyl sulfamate as nitrogen source is the key to achieve desired chemoselectivity. A series of terminal amine derivatives are prepared using this protocol and the sulfonyl group can be removed with basic hydrolysis. The reaction is suggested to proceed via a continuous anodic oxidation, deprotonation, anodic oxidation, and intermolecular nucleophilic addition pathway, demonstrating the first example of electrochemical cinnamyl C—H amination. 展开更多
关键词 ELECTROCHEMISTRY C-H AMINATION SULFAMATE catalyst free
Dietary approach and gut microbiota modulation for chronic hepatic encephalopathy in cirrhosis 预览
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作者 Daniela Campion Ilaria Giovo +3 位作者 Paola Ponzo Giorgio M Saracco Federico Balzola Carlo Alessandria 《世界肝病学杂志:英文版(电子版)》 2019年第6期489-512,共24页
Hepatic encephalopathy(HE)is a common and serious neuropsychiatric complication of cirrhosis,acute liver failure,and porto-systemic shunting.HE largely contributes to the morbidity of patients with liver disease,sever... Hepatic encephalopathy(HE)is a common and serious neuropsychiatric complication of cirrhosis,acute liver failure,and porto-systemic shunting.HE largely contributes to the morbidity of patients with liver disease,severely affecting the quality of life of both patients and their relatives and being associated with poor prognosis.Its presentation is largely variable,manifesting with a broad spectrum of cognitive abnormalities ranging from subtle cognitive impairment to coma.The pathogenesis of HE is complex and has historically been linked with hyperammonemia.However,in the last years,it has become evident that the interplay of multiple actors,such as intestinal dysbiosis,gut hyperpermeability,and neuroinflammation,is of crucial importance in its genesis.Therefore,HE can be considered a result of a dysregulated gut-liverbrain axis function,where cognitive impairment can be reversed or prevented by the beneficial effects induced by“gut-centric”therapies,such as non-absorbable disaccharides,non-absorbable antibiotics,probiotics,prebiotics,and fecal microbiota transplantation.In this context dietary modifications,by modulating the intestinal milieu,can also provide significant benefit to cirrhotic patients with HE.This review will provide a comprehensive insight into the mechanisms responsible for gut-liver-brain axis dysregulation leading to HE in cirrhosis.Furthermore,it will explore the currently available therapies and the most promising future treatments for the management of patients with HE,with a special focus on the dietary approach. 展开更多
关键词 CIRRHOSIS Hepatic encephalopathy DIET therapy GUT MICROBIOTA Leaky GUT HYPERAMMONEMIA Prebiotics Probiotics Gluten-casein free DIET GUT MICROBIOTA transplantation
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gt-C3N4 coordinated single atom as an efficient electrocatalyst for nitrogen reduction reaction
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作者 Lifu Zhang Wanghui Zhao +2 位作者 Wenhua Zhang Jing Chen Zhenpeng Hu 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第5期1181-1186,共6页
The electrochemical reduction of nitrogen to ammonia is a promising way to produce ammonia at mild condition.The design and preparation of an efficient catalyst with high ammonia selectivity is critical for the real a... The electrochemical reduction of nitrogen to ammonia is a promising way to produce ammonia at mild condition.The design and preparation of an efficient catalyst with high ammonia selectivity is critical for the real applications.In this work,a series of transition metal (TM =Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn,Y,Zr,Nb,Mo,Tc,Ru,Rh,Pd,Ag,and Cd) atoms supported by gt-C3N4 (TM/gt-C3N4) are investigated as electrocatalysts for the nitrogen reduction reaction (NRR) based on density functional calculations.It is found that Mo/gt-C3N4 with a limiting potential of-0.82 V is the best catalyst for standing-on adsorbed N2 cases.While for lying-on adsorbed N2 cases,V/gt-C3N4 with a limiting potential of-0.79 V is berer than other materials.It is believed that this work provides several promising candidates for the non-noble metal electrocatalysts for NRR at mild condition. 展开更多
关键词 NITROGEN reduction reaction SINGLE-ATOM catalyst FIRST-PRINCIPLES calculation Gibbs free energy
Heavy metal free primers: Polymorphism of gadolinium and titanium in the context of GSR glass phase 预览
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作者 Felice Nunziata 《Defence Technology(防务技术)》 CAS CSCD 2019年第3期272-275,共4页
The possibility of identifying gunshot residue (GSR) particles produced by non-toxic primers containing only titanium and zinc is a very difficult task using SEM/EDX analysis employed in the analysis of GSR originatin... The possibility of identifying gunshot residue (GSR) particles produced by non-toxic primers containing only titanium and zinc is a very difficult task using SEM/EDX analysis employed in the analysis of GSR originating from primers containing lead, barium and antimony. However, Bauer et al. demonstrated that non-toxic (TieZn) primers form a TiZn2O4 spinel crystalline structure using SEM/EDX with EBSD (Electron Back Scatter Diffraction) and TKD (Transmission Kikuchi Diffraction), whereas GSR originating from gadolinium-doped TieZn primers form a non-crystalline glass phase. Here, a possible explanation of these different phenomena is hypothesized. 展开更多
关键词 GSR Heavy metal free PRIMERS GADOLINIUM Glass phase EBSD TKD
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