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The novel usage of thiourea nitrate in aryl nitration

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Chinese Chemical Letters 2014年第1期25卷 87-89页

作者： Ge Meng mei-Lin zheng A-Qun zheng mei Wang Juan Shi School of Pharmacy Xi’an Jiaotong University School of Science Xi’an Jiaotong University

Thiourea nitrate （TN） was easily prepared from thiourea and nitric acid to explore its use as a new nitration reagent, Nitrations of various aromatic compounds utilizing TN in concentrated sulfuric acid were studied, TN could convert aromatic compounds to the corresponding nitrated derivatives with various abnormal yields under mild conditions. The results suggested that the reaction mechanism might be different from those of traditional nitration reagents.

关键词： Thiourea nitrate Nitration Thiourea Aromatic compounds

Multifunctional ultrasmall Pd nanosheets for enhanced near-infrared photothermal therapy and chemotherapy of cancer

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Nano Research 2015年第1期8卷 165-174页

作者： Shaoheng Tang mei Chen Nanfeng zheng State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials andDepartment of Chemis try College of Chemistry and Chemical Engineering Xiamen University Xiamen Fujian 361005 China

Near-infrared （NIR） photothermal therapy has developed very quickly in recent years. However, its clinical applications are hindered by many practical problems, such as low accumulation in tumors, high laser power density and high biotoxicity in vivo. Herein, a versatile system combining chemotherapy with photothermal therapy for cancer therapy using ultrasmall Pd nanosheets （SPNS） has been developed. The SPNS can serve as pH-responsive drug carriers to efficiently deliver DOX into cancer cells and tumors. On the other hand, the coordinative loading of DOX on SPNS enhances its accumulation in tumor tissue. So we can efficiently ablate tumor using low-intensity laser radiation. Importantly, with ultrasmall size （-4.4 nm）, SPNS surface-functionalized with reduced glutathione （GSH） can be cleared from the body through the renal system into the urine. This cancer therapeutic nanosystem, which exhibits a significant synergistic effect and low systemic toxicity, has great potential for clinical applications.

关键词： photothermal therapy chemotherapy Pd nanosheets drug delivery synergistic effect

Nuclear TAR DNA-binding protein 43 A new target for amyotrophic lateral sclerosis treatment

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Neural Regeneration Research 2013年第35期8卷 3284-3295页

作者： mei zheng Yujie Shi Dongsheng Fan Department of Neurology Peking University Third Hospital School of Pharmaceutical Sciences Peking University

Abnormal TAR DNA-binding protein 43 （TDP-43） inclusion bodies can be detected in the degen- erative neurons of amyotrophic lateral sclerosis. In this study, we induced chronic oxidative stress injury by applying malonate to cultured mouse cortical motor neurons. In the later stages of the malonate insult, TDP-43 expression reduced in the nuclei and transferred to the cytoplasm. This was accompanied by neuronal death, mimicking the pathological changes in TDP-43 that are seen in patients with amyotrophic lateral sclerosis. Interestingly, in the early stages of the response to malonate treatment, nuclear TDP-43 expression increased, and neurons remained relatively intact, without inclusion bodies or fragmentation. Therefore, we hypothesized that the increase of nuclear TDP-43 expression might be a pro-survival factor against oxidative stress injury. This hypothesis was confirmed by an in vitro transgenic experiment, in which overexpression of wild type mouse TDP-43 in cultured cortical motor neurons significantly reduced malonate-induced neuronal death. Our findings suggest that the loss of function of TDP-43 is an important cause of neuronal degen- eration, and upregulation of nuclear TDP-43 expression might be neuroprotective in amyotrophic lateral sclerosis.

关键词： neural regeneration neurodegenerative disease amyotrophic lateral sclerosis TAR DNA-bindingprotein 43 cortex motor neurons oxidative stress sodium malonate neuroprotection grants-supported paper neurodegeneration

Admissible Solutions of Systems of Complex Partial Difference Equations on C^n

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Acta Mathematicae Applicatae Sinica 2015年第2期31卷 297-306页

作者： Ling-yun GAO Ze-mei zheng Department of Mathematics Jinan University Guangzhou

In a recent papers,some authors applied Nevanlinna theory to prove some results on complex difference equations reminiscent of the classical Malmquist theorem in complex differential equations. We will mainly investigate Malmquist theorem of a type of systems of complex partial difference equations on Cn,improvements and extensions of such results are presented in this paper.

关键词： Malmquist type meromorphic solution value distribution partial difference equations

The Ruin Probability of the Renewal Model with Constant Interest Force and Upper-tailed Independent Heavy-tailed Claims

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Acta Mathematica Sinica,English Series 2010年第9期26卷 1815-1826页

作者： Xin mei SHEN zheng Yan LIN Department of Mathematics Zhejiang University Hangzhou 310027 P. R. China

In this paper, we obtain the uniform estimate for discounted aggregate claims in the continuous-time renewal model of upper-tailed independent and heavy-tailed random variables. With constant interest force and constant premium rate, we establish a uniform simple asymptotic formula for ruin probability of the renewal model in the case where the initial surplus is large.

关键词： Asymptotic estimate consistent variation renewal process upper-tail independent

Developing chemical signatures of particulate air pollution in the Pearl River Delta region, China

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Journal of Environmental Sciences 2011年第7期23卷 1143-1149页

作者： mei zheng Yuan Cheng Limin Zeng Yuanhang Zhang College of Environmental Sciences and Engineering Peking University Beijing 100871 China School of Earth and Atmospheric Sciences Georgia Institute of Technology Atlanta GA 30332 USA

PM 2.5 samples were collected in a regional sampling network with three sites in Hong Kong and four sites in the adjacent inland Pearl River Delta （PRD） or Guangdong Province during four months/seasons from 2002–2003. Trans-boundary transport between Hong Kong and the inland PRD is inevitable under the influence of Asian monsoon. In summer, Hong Kong serves as the upwind site of the inland PRD while during other seasons it is under the influence of continental emissions. Previous studies have recognized the importance of using chemical signatures to differentiate local vs. regional contributions to air pollutants in Hong Kong such as the CO/NOx ratio, ratios of different VOC species. In this study, detailed chemical speciation by gas chromatography-mass spectrometry was performed with PM 2.5 samples to identify new chemical signatures to distinguish aerosols in Hong Kong from those from the inland PRD. Since Hong Kong is not influenced by the continental emissions from the inland PRD during summer, comparison focused on chemical data obtained from this season for chemical signatures. The new ratios developed from the current study include LCPI/HCPI ratio of alkanes （0.39 ± 0.02 in Hong Kong vs. 0.78 ± 0.08 in the inland PRD）, pyrene to benzo[ghi]perylene ratio （0.97 ± 0.21 in Hong Kong compared to 0.20 ± 0.06 in the inland PRD）, and the ratio of 1,2-benzenedioic acid to 1,4-benzenedioic acid （1.8 ± 0.1 in Hong Kong vs. 0.6 ± 0.05 in the inland PRD）. Results from this study also revealed that Hong Kong was impacted by ship emissions as reflected by substantially high V/Ni ratio （9 ± 2） while this ratio was about 1–2 at all sites in the inland PRD, which is very close to typical ratios from residual oil combustion.

关键词： PM 2.5 chemical signature local and regional air pollution Hong Kong Pearl River Delta

Chinese multi-document personal name disambiguation

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High Technology Letters 2005年第3期11卷 280-283页

作者： Wang Houfeng（王厚峰） mei zheng Department of Computer Science and Technology Peking University Beijing 100871 P. R. China

This paper presents a new approach to determining whether an interested personal name across doeuments refers to the same entity. Firstly,three vectors for each text are formed： the personal name Boolean vectors denoting whether a personal name occurs the text the biographical word Boolean vector representing title, occupation and so forth, and the feature vector with real values. Then, by combining a heuristic strategy based on Boolean vectors with an agglomeratie clustering algorithm based on feature vectors, it seeks to resolve multi-document personal name coreference. Experimental results show that this approach achieves a good performance by testing on ＂Wang Gang＂ corpus.

关键词： personal name disambiguation Chinese multi-document heuristic strategy. agglomerative clustering

Theoretical Study on the Dehydrogenation Reaction of H_2S by VS^+ (~3Σ^-)

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Chinese Journal of Structural Chemistry 2005年第10期24卷 1111-1116页

作者： GAO Shu-Lin LIU zheng-mei XIE Xiao-Guang Department of Chemistry Yunnan University Kunming 650091 China School of Physics and Chemistry Guizhou Normal University Guiyang 550001 China

The dehydrogenation reaction of H2S by the ^3Σ^- ground state of VS^＋： VS^＋＋ H2S → VS2^＋＋ H2 has been studied by using Density Functional Theory （DPT） at the B3LYP/DZVP level. It is found that the reaction proceeds along two possible pathways （A and B） yielding two isomer dehydrogenation products VS2^＋-1 （^3B2） and VS2^＋-2 （^3A1）, respectively. For both pathways, the reaction has a two-step-reaction mechanism that involves the migration of two hydrogen atoms from S2 to V^＋, respectively. The migration of the second hydrogen via TS3 and that of the first via TS4 are the rate-determining steps for pathways A and B, respectively. The activation energy is 17.4 kcal/mol for pathway A and 22.8 kcal/mol for pathway B relative to the reactants. The calculated reaction heat of 9.9 kcal/mol indicates the endothermicity of pathway A and that of -11.9 kcal/mol suggests the exothermicity of pathway B.

关键词： density functional theory cationic transition metal sulfide,dehydrogenation reaction reaction mechanism

Effects of flow parameters on thermal performance of an inner-liner anti-icing system with jets impingement heat transfer

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Chinese Journal of Aeronautics 2021年第9期34卷 119-132页

作者： Zhiqiang GUO mei zheng Qian YANG Xiaofeng GUO Wei DONG School of Mechanical Engineering Shanghai Jiaotong UniversityShanghai 200240China

The multiple jets impingement heat transfer is widely applied in the wing anti-icing *** is challenging to apply the similarity criterion to carry out the anti-icing experiments due to the complex flow and heat transfer *** the present study,the full-scale slat model is used to carry out anti-icing experimental researches in a 2 m×3 m icing wind tunnel of China Aerodynamics Research and Development *** effects of icing parameters Liquid Water Content(LWC)and Median Volume Diameter(MVD)and hot air parameters(mass flow rate and temperature)on the thermal performance of an inner-liner anti-icing system with jets impingement heat transfer are *** effects of the experimental parameters are analyzed in detail by combining impingement and evaporation heat transfer *** impingement hot air mass flow rate dramatically affects the heat transfer performance of the impingement stagnation region within the range of the experimental *** temperature of impingement hot air and that of wing skin are approximately linear *** experimental results show the effects of LWC and MVD on water film formation and runback ice *** formation of water film is analyzed by an analytical method based on the wing skin temperature difference of dry and wet air conditions.

关键词： Hot air anti-icing system Icing Icing wind tunnel Jets impingement heat transfer Thermal performance