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A novel TOA estimation method with effective NLOS error reduction

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The Journal of China Universities of Posts and Telecommunications 2008年第1期15卷 32-37页

作者： zhang Yi-heng CUI Qi-mei li Yu-xiang zhang Ping Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications Ministry of Education Wireless Technology Innovation Institute (WTI) Beijing 100876 China

It is well known that non-line-of-sight （NLOS） error has been the major factor impeding the enhancement of accuracy for time of arrival （TOA） estimation and wireless positioning. This article proposes a novel method of TOA estimation effectively reducing the NLOS error by 60%, comparing with the traditional timing and synchronization method. By constructing the orthogonal training sequences, this method converts the traditional TOA estimation to the detection of the first arrival path （FAP） in the NLOS multipath environment, and then estimates the TOA by the round-trip transmission （RTT） technology. Both theoretical analysis and numerical simulations prove that the method proposed in this article achieves better performance than the traditional methods.

关键词： TOA estimation NLOS error B3G

High Quality Zinc Sulfide Epitaxial Layers Grown by Metalorganic Chemical Vapour Deposition

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Rare Metals 1989年第2期9卷 37-42页

作者： Fan, Guanghan liao, Qiwei Fan, Xiwu zhang, Zhishun li, mei zhang, Jiying Changchun Inst of Physics China

ZnS films were successfully grown by metallorganic chemical vapour deposition (MOCVD) at atmospheric pressure on (100) GaAs substrates. The deposition was carried out at a substrate temperature between 280 approximately 550°C with optimisation of reactor design and growth conditions. The gas phase prereaction is effectively restrained. These epilayers exhibit high crystallographic quality and reveal a mirror surface morphology. The peak halfwidths of X-ray diffraction patterns from their (400) faces are within 0.06 approximately 0.09°. The epilayers grown on (111) GaAs, (112¯0) Al2O3 and (100) Si have proven to be single crystalline feature. The optical and electrical characteristics of ZnS epilayers are measured by photoluminescence, cathodeluminescence, and the Van der Pauw method. The results indicate that there are not a large number of deep centers that could be detected both at 77K and at room temperature. A broad CL peak around 2.897eV and 2.672eV was observed only under very strong excitation. Their origin has not been examined. All epilayers present high resistivities up to 1013Ω·cm.

关键词： Crystals Epitaxial Growth Optical Properties Measurements Organometallics Chemical Vapor Deposition Semiconducting Gallium Arsenide Substrates Semiconducting Zinc Compounds

Copper pollution decreases the resistance of soil microbial community to subsequent dry–rewetting disturbance

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Journal of Environmental Sciences 2016年第1期28卷 155-164页

作者： Jing li Jun-Tao Wang Hang-Wei Hu Yi-Bing Ma li-mei zhang Ji-Zheng He State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Faculty of Veterinary and Agricultural Sciences The University of Melbourne National Soil Fertility and Fertilizer Effects Long-term Monitoring Network Institute of Agricultural Resources and Regional PlanningChinese Academy of Agricultural Sciences

Dry–rewetting（DW） disturbance frequently occurs in soils due to rainfall and irrigation, and the frequency of DW cycles might exert significant influences on soil microbial communities and their mediated functions. However, how microorganisms respond to DW alternations in soils with a history of heavy metal pollution remains largely ***, soil laboratory microcosms were constructed to explore the impacts of ten DW cycles on the soil microbial communities in two contrasting soils（fluvo-aquic soil and red soil）under three copper concentrations（zero, medium and high）. Results showed that the fluctuations of substrate induced respiration（SIR） decreased with repeated cycles of DW alternation. Furthermore, the resistance values of substrate induced respiration（RS-SIR）were highest in non-copper-stressed（zero） soils. Structural equation model（SEM） analysis ascertained that the shifts of bacterial communities determined the changes of RS-SIR in both soils. The rate of bacterial community variance was significantly lower in noncopper-stressed soil compared to the other two copper-stressed（medium and high） soils,which might lead to the higher RS-SIR in the fluvo-aquic soil. As for the red soil, the substantial increase of the dominant group WPS-2 after DW disturbance might result in the low RS-SIR in the high copper-stressed soil. Moreover, in both soils, the bacterial diversity was highest in non-copper-stressed soils. Our results revealed that initial copper stress could decrease the resistance of soil microbial community structure and function to subsequent DW disturbance.

关键词： Copper stress Dry–rewetting disturbance Bacterial community Substrate induced respiration Resistance

Preparation and characterization of optically functional hollow sphere hybrid materials by surface-initiated RATRP and "click" chemistry

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Chinese Chemical Letters 2013年第4期24卷 335-337页

作者： Xin-Hu Lv li-Ping Wang Guang li Xue-Xi Gao Pan-Pan Pan li-mei zhang College of Materials Science and Engineering Liaocheng University School of Physical Science and Information Technology Liaocheng University

The random copolymers grafted onto the surfaces of SiO2 hollow sphere via reverse atom transfer radical polymerization （RATRP） and ＂click＂ chemistry were investigated. A sufficient amount of peroxides, as initiating moieties, were introduced onto the surface of hollow spheres. Then styrene and 4-vinylbenzyl azide were polymerized via surface-initiated reverse atom transfer radical polymerization （SI-RATRP） using the peroxide group modified hollow sphere as initiator, resulting in hollow spheres （HS） with grafted polystyrene-co-poly（4-vinylbenzyl azide） copolymer brushes as （HS-g-PS-co-PVBA） intermedi- ate material. Subsequently, N-propargyl-carbazole （PC） was covalently bonded to HS-g-PS-co-PVBA by the ＂click＂ reaction, resulting in the HS-g-PS-co-PVBPC hybrid material. The excitation spectrum is dominated by a broad band from 350 nm to 400 nm with the maximum peak at 362 nm, attributed to the characteristic absorption of the carbazole grouD of HS-g-PS-co-PVBPC hybrid material.

关键词： Hollow sphereRATRP"Click" chemistry4-Vinylbenzyl azide

G-protein beta 3 subunit polymorphisms and essential hypertension： a case-control association study in northern Han Chinese

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Journal of Geriatric Cardiology 2015年第2期12卷 127-134页

作者： mei li Bei zhang Chuang li Jie-lin liU li-Juan WANG Ya liU Zuo-Guang WANG Shao-Jun WEN Department of Hypertension Research Beijing Anzhen Hospital Capital Medical University and Beijing Institute of Heart Lung and Blood Vessel DiseasesBeijing 100029 China

Objective To explore the association between the three polymorphisms [ C825T, C1429T and G（-350）A] of the gene encoding the G protein beta 3 subunit （GNB3） and hypertension by performing a case-control study in the northern Han Chinese population. Methods We recnaited 731 hypertensive patients and 673 control subjects （the calculated power value was 〉 0.8）. Genotyping was performed to identify C825T, C1429T and G（-350）A polymorphisms using the TaqMan assay. Comparisons of allelic and genotypic frequencies between cases and controls were made by using the chi-square test. Logistic regression analyses were performed to investigate the relationships between the three polymorphisms of GNB3 gene under different genetic models （additive, dominant and recessive models）. Results The genotype dis- tribution and allele frequencies of C825T, C1429T and G（-350）A polymorphisms did not differ significantly between hypertensive patients and control subjects, either when the full sample was assessed, or when the sample was stratified by gender. No significant association was observed between C825T, C 1429T and G（-350）A polymorphisms and the risk of essential hypertension in any genetic model. linkage dis- equilibrium was only detected between C825T and C 1429T polymorphisms. Haplotype analyses observed that none of the three estimated haplotypes significantly increased the risk of hypertension. Conclusions Our study suggested that the GNB3 gene polymorphisms [C825T, C 1429T and G（-350）A] were not significantly associated with essential hypertension in northern Han Chinese population.

关键词： G protein beta 3 subunit gene Haplotype Hypertension Polymorphism

Investigation of Urination Disorder in Parkinson＇s Disease

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Chinese Medical Journal 2015年第21期128卷 2906-2912页

作者： li-mei zhang Xu-Ping zhang Department of Neurology Second Affiliated Hospital of Harbin Medical University Harbin Heilongjiang 150086 China

Background： Urination disorders are common in Parkinson＇s disease （PD） and respond poorly to medication. This study aimed to analyze the risk factors for urination disorders in PD. Methods： Ninety-one patients with PD （aged 34-83 years old） were recruited. Patients were assessed with the Unified PD Rating Scale （UPDRS）, Hoehn and Yahr stage, Pittsburgh Sleep Quality Index （PSQ1）, Hamilton Depression Rating Scale （HAMD）, and Hamilton Anxiety Scale （HAMA）. Micturition number was recorded, and Type B ultrasound was used to evaluate residual urine. Statistics was performed using binary logistic regression, bivariate correlations, and Chi-square and t-tests. Results： Of 91 patients, urinary dysfunction occurred in 55.0%. Among these, 49.5% suffered with nocturia, 47.3% with pollakiuria. Nocturia number had a positive linear relationship with HAMA score （odds ratio [OR] = 0.340, P = 0.001 ）, HAMD score （OR = 0.323, P = 0.002）, duration of L-dopa medication （OR = 0.328, P = 0.001 ）, dose of L-dopa （OR = 0.273, P = 0.009）, UPDRS-II （OR = 0.402, P = 0.000）, UPDRS-III score （OR = 0.291, P = 0.005）, and PSQI score （OR = 0.249, P = 0.017）. Micturition number over 24 h was positively associated with HAMA （OR = 0.303, P = 0.004） and UPDRS-II scores （OR = 0.306, P = 0.003）. Of patients with residual urine, 79.3% had a volume of residual urine 〈50 ml. Residual urine was present in 44.4% of the patients with nocturia~ 46.5% of the patients with pollakiuria, and 80.0% of the patients with dysuria. More men than women had residual urine （35.2% male vs. 13.3% female; P = 0.002）. Conclusions： Nocturia and pollakiuria were common micturition symptoms in our participants with PD. Nocturia was associated with depression, anxiety, sleep problems, and severity of PD. Pollakiuria was associated with anxiety and severity of PD. Male patients were more prone to residual urine and pollakiuria.

关键词： Nocturia Parkinson's Disease Risk Factors: Urine Disorders

Microstructural evolution during the progressive transformation-induced plasticity effect in a Fe-0.1C-5Mnmedium manganese steel

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 369-379页

作者： mei zhang Wenhao li Yangfei Chen Yang Jiang Xiaofei Guo Han Dong School of Materials Science and Engineering Shanghai UniversityShanghai 200444China State Key Laboratory of Advanced Special Steel Shanghai UniversityShanghai 200444China

The microstructural evolution of a cold-rolled and intercritical annealed medium-Mn steel(Fe-0.10C-5Mn)was investigated during uniaxial tensile ***-situ observations under scanning electron microscopy,transmission electron microscopy,and X-ray diffraction analysis were conducted to characterize the progressive transformation-induced plasticity process and associated fracture initiation *** findings were discussed with the local strain measurements via digital image *** results indicated that Lüders band formation in the steel was limited to 1.5%strain,which was mainly due to the early-stage martensitic phase transformation of a very small amount of the less stable large-sized retained austenite(RA),which led to localized stress concentrations and strain hardening and further retardation of *** small-sized RA exhibited high stability and progressively transformed into martensite and contributed to a stably extended Portevin-Le Chatelier *** volume fraction of RA gradually decreased from 26.8%to 8.2%prior to *** the late deformation stage,fracture initiation primarily occurred at the austenite/martensite and ferrite/martensite interfaces and the ferrite phase.

关键词： medium-Mn steel retained austenite progressive transformation-induced plasticity effect local strain fracture initiation

Four new diterpenoid alkaloids with antitumor effect from Aconitum nagarum var. heterotrichum

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Chinese Chemical Letters 2017年第2期28卷 358-361页

作者： Da-Ke Zhao Xing-Qiao Shi li-mei zhang Dong-Qiong Yang Hua-Chun Guo Yan-Ping Chen Yong Shen School of Agriculture Yunnan University Kunming 650091 China College of Agriculture and Biotechnology Yunnan Agricultural University Kunming 650201 China State Key Laboratory of Phytochemistry and Plant Resources in West China Kunming Institute of Botany Chinese Academy of Sciences Kunming 650201 China

Four new diterpenoid alkaloids,nagaconitines A-D（1-4）,were isolated from the roots of Aconitum nagarum *** structures were elucidated as 8-（4＇-hydroxylbutyryl） aconitine（1）,15-oxo-13-deoxyludaconitine（2）,15-hydroxyldelphisine（3）,and 14-hydroxyl-2- acetoxyspiradine C（4）based on extensive UV,IR,MS,1D NMR and 2D NMR *** 3-4 showed inhibition of cancer cell line SK-OV-3 with 31%（IC_（50） 43.78 μmol/L） and 24%（IC_（50） 32.14 μmol/L）,respectively.

关键词： Ranunculaceae Aconitum nagarum var.heterotrichum Diterpenoid alkaloids Nagaconitines A-D Antitumor activity

Attenuation of myocardial apoptosis by alpha-lipoic acid through suppression of mitochondrial oxidative stress to reduce diabetic cardiomyopathy

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Chinese Medical Journal 2009年第21期122卷 2580-2586页

作者： li Chun-jun zhang Qiu-mei li Ming-zhen zhang Jing-yun YU Pei YU De-min The Ministry of Health Key Laboratory of Hormone and Development Department of Endocrinology Metabolic Disease Hospital of Tianjin Medical University Tianjin 300070 China

Background Cardiac failure is a leading cause of the mortality of diabetic patients. In part this is due to a specific cardiomyopathy, referred to as diabetic cardiomyopathy. Oxidative stress is widely considered to be one of the major factors underlying the pathogenesis of the disease. This study aimed to test whether the antioxidant α-lipoic acid （α-LA） could attenuate mitochondrion-dependent myocardial apoptosis through suppression of mitochondrial oxidative stress to reduce diabetic cardiomyopathy. Methods A rat model of diabetes was induced by a single tail intravenous injection of streptozotocin （STZ） 45 mg/kg. Experimental animals were randomly assigned to 3 groups： normal control （NC）, diabetes （DM） and DM treated with α-LA （α-LA）. The latter group was administered with a-LA （100 mg/kg ip per day）, the remainder received the same volume vehicle. At weeks 4, 8, and 12 after the onset of diabetes, cardiac apoptosis was examined by TUNEL assay. Cardiomyopathy was evaluated by assessment of cardiac structure and function. Oxidative damage was evaluated by the content of malondialdehyde （MDA）, reduced glutathione （GSH） and the activity of manganese superoxide diamutase （Mn-SOD） in the myocardial mitochondria. Expression of caspase-9 and caspase-3 proteins was determined by immunohistochemistry and mitochondrial cytochrome c release was detected by Western blotting Results At 4, 8, and 12 weeks after the onset of diabetes, significant reductions in TUNEL-positive cells, caspase-9,-3 expression, and mitochondrial cytochrome c release were observed in the α-LA group compared to the DM group. In the DM group, the content of MDA in the myocardial mitochondria was significantly increased, and there was a decrease in both the mitochondrial GSH content and the activities of Mn-SOD. They were significantly improved by α-LA treatment. HE staining displayed structural abnormalities in diabetic hearts, while α-LA reversed this structural derangement. The index of cardiac fun

关键词： alpha-lipoic acid myocardial apoptosis mitochondrial oxidative stress diabetic cardiomyopathy