bluuebunny/crossref_metadata_2025 huggingface dataset:
Advice for Elderly Drivers in a German Memory Clinic: A Case Report on Medical, Ethical and Legal Consequences
Authors: Spannhorst Stefan , Toepper Max , Schulz Philipp , Wenzel Gudrun , Driessen Martin , Kreisel Stefan
Published: March 2016

We report on a 75-year-old female who consulted our Memory Clinic because of subjective memory complaints that she first recognized three months previously. Next to the standard detailed patient history, neuropsychological assessment, psychopathological status, the patient’s driving history played an important role in the diagnostic process. In this case report, we illustrate the diagnostic process starting with the first consultation, including a short neuropsychological examination and communicating its results, reporting on further work-up (detailed neuropsychological assessment, MRI scan and cerebrospinal fluid (CSF) analysis) up to the final consultation, including advice for the patient. We will focus on several medical, ethical and legal difficulties that may occur when consulting elderly drivers with initial cognitive decline.
Work-Recreation Balance, Health-Promoting Lifestyles and Suboptimal Health Status in Southern China: A Cross-Sectional Study
Authors: Wu Shengwei , Xuan Zhengzheng , Li Fei , Xiao Wei , Fu Xiuqiong , Jiang Pingping , Chen Jieyu , Xiang Lei , Liu Yanyan , Nie Xiaoli , Luo Ren , Sun Xiaomin , Kwan Hiuyee , Zhao Xiaoshan
Published: March 2016

Suboptimal health status (SHS)—an intermediate state between health and illness—refers to functional somatic symptoms that are medically undiagnosed. Although SHS has become a great challenge for global public health, very little about its etiology and mechanisms are known. Work-recreation balance is a part of work−life balance, and is related to stress which greatly influences health status. We therefore carried out a cross-sectional investigation between 2012 and 2013 within a clustered sample of 24,475 individuals aged 15−60 years from a population in southern China. In so doing, we hoped to illuminate the associations between work-recreation balance conditions, healthy lifestyles, and SHS. Work-recreation balance conditions were categorically defined by frequency (“rarely, sometimes, or always”). Health-Promoting Lifestyle Profile (HPLP-II) was used to evaluate the level of healthy lifestyles, and the medical examination report and Sub-Health Measurement Scale V1.0 (SHMS V1.0) were both used to evaluate health status. The ratio of SHS (46.3%) is higher than health status (18.4%) or disease status (35.3%). Overall, 4.9% of respondents reported the lowest level of work-recreation balance, and they scored lower on both the HPLP-II and SHMS V1.0 compared with those who frequently maintained a work-recreation balance. Significant association was found between work-recreation balance behaviors and healthy lifestyles (p < 0.001) after demographic adjustment. In comparison with those reporting a frequent work-recreation balance, individuals whose work-recreation balance was categorically “rare” were 1.69 times as likely to develop SHS (odds ratio (OR): 1.69, 95% confidence interval (CI): 1.49–1.92), and those with infrequent work-recreation balance (“sometimes”) were 1.71 times more likely to develop SHS (OR: 1.71, 95% CI: 1.62–1.81). These findings suggest that work-recreation balance conditions are significantly associated with, and seem to be accurate behavioral indicia of a healthy lifestyle. Poor work-recreation balance is associated with increased risk for SHS; thus, a healthier lifestyle that maintains a work-recreation balance should be promoted in order to reduce the development of SHS or disease in southern China.
EQ-5D-5L in the General German Population: Comparison and Evaluation of Three Yearly Cross-Section Surveys
Authors: Huber Manuel , Reitmeir Peter , Vogelmann Martin , Leidl Reiner
Published: March 2016

Health-related quality of life (HRQoL) is a key measure for evaluating health status in populations. Using the recent EQ-5D-5L for measurement, this study analyzed quality of life results and their stability over consecutive population surveys. Three cross-section surveys for representative samples of the general German population from 2012, 2013, and 2014 were evaluated using the EQ-5D-5L descriptive system and valuation by the Visual Analog Scale (VAS). Aggregated sample size reached 6074. The dimension with the highest prevalence of problems was pain/discomfort (31.7%). Compared with 2012 (59.3%), the percentage of participants in the best health state increased slightly in 2013 (63.4%) and 2014 (62%). Over the 3-year period, diabetes and heart disease had the strongest negative influence on mean VAS result. The number of reported chronic diseases cumulatively reduced mean VAS. Extreme problems in one or more dimensions were stated by only 0.1%–0.2% of patients. Of the potential 247 health states with a problem score ≥20, only six were observed in the aggregated sample. HRQoL results were fairly stable over the 3 years, but the share of the population with no problems was not. Results from the aggregated sample may serve as updated reference values for the general German population.
Health Risks Associated with Oil Pollution in the Niger Delta, Nigeria
Authors: Nriagu Jerome , Udofia Emilia , Ekong Ibanga , Ebuk Godwin
Published: March 2016

Background: Although there is considerable public concern about the environmental impacts of oil pollution in the Niger Delta of Nigeria, actual evidence on the pathological and psychological effects in the health of local communities is minimally known. We sought to associate the perspective measures of exposure to oil pollution with health outcomes (inventory of health symptoms and functional capacity limitations) and determine how emotional reactions to environmental risks moderate these health outcomes. Method: The study was conducted with 600 participants selected from five local government areas in Akwa Ibom State where oil pollution is rampant. A structured questionnaire was used to collect the data on the respondents’ exposure to oil pollution, self-rated health and disease symptoms, perception of risk of exposure and emotional reactions to local oil pollution. Results: Most of the participants lived in areas with visible oil pollution and/or near gas flaring facilities and regularly suffered direct exposure to oil in their environment. High level of emotional distress was a part of everyone's life for the study population. Risk perception in the study area was mediated, to a large extent, by dreaded hazards (catastrophic fears of pipeline explosions and oil spill fire), visual cues (gas flares and smoke stacks) and chemosensory cues (off-flavor in drinking water). The exposure metrics were found to be significant predictors of the health effects and influencing factors (emotional reactions). Multi-levels models suggest that at the individual level, the demographic variables and direct contact with oil pollution were important mediators of functional capacity limitation. At the community level, emotional distress from fear of the sources of exposure was an important mediator of the health symptoms. Conclusions: This study documents high levels of disease symptoms and environmental distress (worry, annoyance and intolerance) associated with oil pollution in the Niger Delta areas of Nigeria. It highlights the need for some intervention to ameliorate the psychological distress associated with living under such environmental adversity.
A Comparative Study of Molecular Structure, pKa, Lipophilicity, Solubility, Absorption and Polar Surface Area of Some Antiplatelet Drugs
Authors: Remko Milan , Remková Anna , Broer Ria
Published: March 2016

Theoretical chemistry methods have been used to study the molecular properties of antiplatelet agents (ticlopidine, clopidogrel, prasugrel, elinogrel, ticagrelor and cangrelor) and several thiol-containing active metabolites. The geometries and energies of most stable conformers of these drugs have been computed at the Becke3LYP/6-311++G(d,p) level of density functional theory. Computed dissociation constants show that the active metabolites of prodrugs (ticlopidine, clopidogrel and prasugrel) and drugs elinogrel and cangrelor are completely ionized at pH 7.4. Both ticagrelor and its active metabolite are present at pH = 7.4 in neutral undissociated form. The thienopyridine prodrugs ticlopidine, clopidogrel and prasugrel are lipophilic and insoluble in water. Their lipophilicity is very high (about 2.5–3.5 logP values). The polar surface area, with regard to the structurally-heterogeneous character of these antiplatelet drugs, is from very large interval of values of 3–255 Å2. Thienopyridine prodrugs, like ticlopidine, clopidogrel and prasugrel, with the lowest polar surface area (PSA) values, exhibit the largest absorption. A high value of polar surface area (PSA) of cangrelor (255 Å2) results in substantial worsening of the absorption in comparison with thienopyridine drugs.
Ochratoxin A Producing Fungi, Biosynthetic Pathway and Regulatory Mechanisms
Authors: Wang Yan , Wang Liuqing , Liu Fei , Wang Qi , Selvaraj Jonathan , Xing Fuguo , Zhao Yueju , Liu Yang
Published: March 2016

Ochratoxin A (OTA), mainly produced by Aspergillus and Penicillum species, is one of the most important mycotoxin contaminants in agricultural products. It is detrimental to human health because of its nephrotoxicity, hepatotoxicity, carcinogenicity, teratogenicity, and immunosuppression. OTA structurally consists of adihydrocoumarin moiety linked with l-phenylalanine via an amide bond. OTA biosynthesis has been putatively hypothesized, although several contradictions exist on some processes of the biosynthetic pathway. We discuss recent information on molecular studies of OTA biosynthesis despite insufficient genetic background in detail. Accordingly, genetic regulation has also been explored with regard to the interaction between the regulators and the environmental factors. In this review, we focus on three aspects of OTA: OTA-producing strains, OTA biosynthetic pathway and the regulation mechanisms of OTA production. This can pave the way to assist in protecting food and feed from OTA contamination by understanding OTA biosynthetic pathway and regulatory mechanisms.
Using GOCI Retrieval Data to Initialize and Validate a Sediment Transport Model for Monitoring Diurnal Variation of SSC in Hangzhou Bay, China
Authors: Yang Xuefei , Mao Zhihua , Huang Haiqing , Zhu Qiankun
Published: March 2016

The diurnal variation of the suspended sediment concentration (SSC) in Hangzhou Bay, China has been investigated using remotely-sensed SSC derived from the Geostationary Ocean Color Imager (GOCI) in combination with a coupled hydrodynamic-ecological model for regional and shelf seas (COHERENS). The SSC maps were inferred through a UV-AC atmospheric correction algorithm and an empirical inversion algorithm from the GOCI Level-1B data. The sediment transport model was initialized from maps of the GOCI-derived SSC and the model results were validated through a comparison with remotely-sensed data. The comparison demonstrated that the model results agreed well with the observations. The relationship between SSC distribution and hydrodynamic conditions was analyzed to investigate the sediment transport dynamics. The model’s results indicate that the action of tidal currents dominate the sediment deposition and re-suspension in the coastal waters of the East China Sea. This is especially the case in Hangzhou Bay where the tidal currents are strongest. The satellite-derived sediment data product can not only dramatically improve the specification of the initial conditions for the sediment model, but can also provide valuable information for the model validation, thereby improving the model’s overall performance.
Les collaborateurs devant la cour d'assises du Nord après la très Grande Guerre.
Authors: Martinage Renée
Published: March 2016

Les deux tiers des accusés d'intelligences avec l'ennemi en France, soit 83 personnes, furent jugés à la cour d'assises du Nord de 1920 à 1925. Le statut de la région pendant la guerre explique la concentration locale de ces crimes dont le nombre absolu demeure faible. Les collaborateurs furent jugés soit pour avoir secondé les Allemands dans les extorsions qu'ils pratiquaient, soit pour leur avoir fourni des renseignements, le plus souvent sous forme de dénonciations.

La rigueur de la cour d'assises fut relative. La moitié des accusés fut acquittée sans doute en raison des difficultés de preuve inévitables dans ces procès tardifs. Les deux tiers des condamnés subirent les peines criminelles politiques spécifiques pour ces infractions, c'est-à-dire la déportation et la détention, car depuis 1848 la peine de mort était abolie en matière politique. Six accusés, dont 3 contumax, furent condamnés à la déportation perpétuelle en enceinte fortifiée (aux îles du Salut à l'époque), en raison de l'accumulation des forfaits commis. 22 personnes furent condamnées à la détention, une peine qui s'exécute dans l'une des forteresses du territoire continental, pour des durées qui varièrent de 5 à 15 ans. Enfin 15 accusés furent condamnés à la peine correctionnelle de l'emprisonnement. Une seule cassation, trois grâces, une seule libération conditionnelle, aucun sursis, tempérèrent peu la lourdeur des châtiments. La justice de la cour d'assises, conforme au niveau de sévérité habituelle dans les années vingt, et liée par les caractéristiques judiciaires des procès, fut peu appréciée par l'opinion publique déçue principalement par l'acquittement des industriels fournisseurs des Allemands.
Interactions between 4-thiothymidine and water-soluble cyclodextrins: Evidence for supramolecular structures in aqueous solutions
Authors: Rizzi Vito , Matera Sergio , Semeraro Paola , Fini Paola , Cosma Pinalysa
Published: March 2016

Since several years the inclusion of organic compounds (guests) within the hydrophobic cavity (host) of cyclodextrins (CDs) has been the subject of many investigations. Interestingly, the formation of inclusion complexes could affect the properties of the guest molecules and, for example, the influence of the delivery system can be a method to improve/change the photochemical behavior of the guest. In particular, very recent studies have shown the protective role of CDs preventing the degradation of the encapsulated guest. Starting from this consideration, in this work, only the structure and complexation mode of the inclusion complexes involving 4-thiothymidine (S4TdR, a known photosensitizer) and five CDs, namely 2-hydroxypropyl-α-cyclodextrin (2-HP-α-CD), 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD), 2-hydroxypropyl-γ-cyclodextrin (2-HP-γ-CD), heptakis-(2,6-di-O-methyl)-β-cyclodextrin (DIMEB CD) and heptakis-(2,3,6-tri-O-methyl)-β-cyclodextrin (TRIMEB CD) were investigated by different spectroscopic techniques (UV–vis, FTIR–ATR, 1H NMR) and cyclic voltammetry analysis (CV). This work is necessary for a prospective research on the photoreactivity of S4TdR in aqueous environment and in the presence of CDs to prevent its degradation under irradiation. UV–vis, FTIR–ATR and CV measurements suggested the formation of supramolecular structures involving the employed CDs and mainly the pyrimidine ring of S4TdR. 1H NMR analyses confirmed such indication, unveiling the presence of inclusion complexes. The strongest and deepest interactions were suggested when TRIMEB and DIMEB CDs were studied. The S4TdR affinity towards CDs was also evaluated by using the Benesi–Hildebrand (B–H) equation at 25 °C employing CV and 1H NMR methods. The stoichiometry of the interaction was also inferred and it appears to be 1:1 for all examined CDs.
Social Media-Based Forecasting
Authors: He Wu , Guo Lin , Shen Jiancheng , Akula Vasudeva
Published: March 2016

Social media-based forecasting has received significant attention from academia and industries in recent years. With a focus on Twitter, this paper investigates whether sentiments of the tweets regarding the 7 largest US financial service companies (in U.S. dollars) are related to the stock price changes of these companies. The authors' findings indicate, in the financial services context, negative sentiments predict firms' future stock prices. However, the number of and the positive sentiment of tweets are not correlated with stock prices. The findings of this paper suggest the possible predictive value of social media data on stock prices at the company level.
Dependence of Negative Substrate Bias on the Optical and Electrical Properties of W-Doped Vanadium Dioxide Thin Films
Authors: Zhu Mao Dong , Zhang Dong Ping , Liu Yi , Yang Kai , Liang Guang Xing , Zheng Zhuang Hao , Fan Ping
Published: March 2016

W-doped VO2 films were prepared by DC reactive magnetron sputtering with various substrate bias. The microstructure, surface morphology, electrical and optical performances of the films were characterized by x-ray diffraction, scanning electron microscope, four-point probe method and spectrophotometer, respectively. The effect of substrate bias on microstructure, electrical and optical properties of sputtered W-doped VO2 films was studied. The XRD results reveal that all samples exhibit preferential VO2 (011) lattice orientation except the as-grown sample in our experiment. All the samples applied substrate bias show some degree optical switching performance in IR range, while the thermochromic phenomena was observed from resistance-temperature dependence plot only for the samples of substrate bias varied from-100V to-200V. This indicate that the optical and electrical properties of W-doped VO2 films have different sensitivity to substrate bias. Optimal substrate bias of-200V sample shows fine semiconductor-metal-transition performance.
Exergy-Based Resource Intensity Analysis of Primary Nickel Production in China
Authors: Sun Bo Xue , Liu Yu , Nie Zuo Ren , Gao Feng , Wang Zhi Hong , Gong Xian Zheng
Published: March 2016

The resource intensity of primary nickel production in China was analyzed by the indicator of exergy, which can provide a unified picture about the overall processes involved in the life cycle of nickel. The results show that primary nickel’s CExD value is 235GJex/t, and the largest contributor to the CExD is electricity (46%), followed by fuels (31%), mineral (16%), and land resource (7%); the considerable proportion natural mineral and land resource account for in the result is due to the high exergy value of sulphide minerals and the low grade of natural nickel ore. The results also show that the calculation of this study is sensitive to the choice of allocation basis (mass and market value); however, market value is not recommended in this study since that nickel’s price varies greatly over time.
Experimental Study on Friction and Wear between Drill Collar and Casing
Authors: Huang Ben Sheng , Zhu Yao
Published: March 2016

Casing wear is one of the key issues in the development of oil and gas fields and in the process of drilling operations. In this study, the relationship between hardness and wear resistance of drill collar and casing was studied; thereby the wear conditions between the two materials were improved. Chemical analysis, optical microscopy, hardness test and friction wear test were conducted to study the effects of heat treatment on hardness of the drill collar 4145H and the casing 30Mn5V, and discuss the relationship between hardness and wear resistance of them. The results showed that the materials of drill collar and casing after different heat treatment had varying degrees of wear, both of the respective wear amounts were gradually increasing with the increase of hardness of them, the wear extent of casing material was greater than that of drill collar material. The hardness of casing material was the lowest and its wear resistance was the best when quenching at 880°C and tempering at 630°C. And when quenching at 900°C and tempering at 690°C, the hardness of drill collar material was the lowest and its wear resistance was the best. Therefore, the hardness of drill collar and casing can be improved by changing the heat treatment process to improve the wear resistance, thereby reducing the wear conditions between them.
Effect of Water Velocity on Underwater In-Service Welding
Authors: Fan Zhou , Hu Xiao Gang , Fu Jing Wen , Ou Yang Xu
Published: March 2016

In-service welding of the pipeline steel is performed under the environment where the delivery of the high pressure pipeline doesn’t stop. When welding under the water, there are high-pressure gas flowing in the pipeline and water flowing outside, causing a difficult and possibly risky of the welding operation. The process of in-service welding with SYSWELD was adopted to establish a geometric model of pipeline repair that the pipeline steel using finite element numerical modeling of the underwater in-service welding was carried out. Furthermore, this study focused on the effect of water velocity on the temperature field and stress field when repairing the in-service pipeline by welding. The results indicated that the water velocity of the pipe has a great influence on the temperature field and the residual stress field.
Effect of Doping Elements on High Temperature Properties of Tungsten Products
Authors: Hu Ya Fang , Yang Jian Can , Liu Zhen
Published: March 2016

The tungsten products including tungsten electrode, tungsten filament, tungsten crucible have been widely used in national production. To study their properties at high temperature can provide a basis for improving the production process and the quality of processing as well as reducing production defects, which has important significance for the optimization of the performance and life extension of tungsten products. In this paper the development of tungsten and tungsten products is briefly introduced, the effects of many kinds of doped elements and doped compounds on high temperature mechanical properties is summarized, the research status of high temperature properties of tungsten products described in detail. And the development direction and application prospects for optimizing the high temperature performance of tungsten products has been out looked,in order to provide a reference for the research on the mechanical properties under high temperature of tungsten products.
Synthesis and Characterization of Porous TiO2 Thin Film Loaded with Cu2ZnSnS4 Nanoparticles
Authors: Zhao Ji Fu , Chen Shui Yuan , Chen Gui Lin , Ye Qing Ying , Hu Bing Lin , Huang Zhi Gao
Published: March 2016

As a promising absorber layer, semiconducting Cu2ZnSnS4 (CZTS) can be applied to replace the organic dye in dye-sensitized solar cell for photovoltaic application because of its good stability, suitable band gap energy (~1.5eV) and large absorption coefficient (~104 cm-1). In this paper, successive ionic layer adsorption and reaction (SILAR) method was utilized to deposit CZTS nanoparticles on mesoporous titanium dioxide (TiO2). This solar cell with carbon film coated FTO glass slide as the back electrode showed an open circuit voltage of 380 mV. Preliminary results obtained for solar cells fabricated with this material are promising.
Electroless CoMoB Diffusion Barrier Layer for ULSI-Cu Metallization
Authors: Liu Xue Mei , Chen Xiu Hua , Ma Wen Hui , Li Yu Ping , Bi Ping , Wang Yun Chun , Xiang Fu Wei
Published: March 2016

CoMoB film was prepared on Si substrate via electroless deposition as the diffusion barrier for ULSI-Cu metallization. Annealing experiments of CoMoB(30nm) film and CoMoB(10nm)/Cu (40nm)/CoMoB(30nm)/SiO2/Si multi-films were carried out in the temperature range from 400◦C to 700◦C. Failure temperature and mechanism of Cu diffusion in CoMoB film were discussed. The composition, sheet resistance and morphology of the film were investigated by X-Ray Diffractometer (XRD), Four Point Probe (FPP) and Atomic Force Microscopy (AFM), respectively. It can be concluded that the failure temperature of CoMoB film is 600◦C. The main reason of failure is that a large number of Cu particles passed through CoMoB grain boundary and reacted with Si substrate to generate Cu4Si with high resistance.
Tunable Dielectric Properties of BaTiO3/La2O3 Composite Ceramics
Authors: Ren Peng Rong , Wang Qian , Wang Xin , Lian Ting , Zhao Gao Yang
Published: March 2016

BaTiO3/La2O3 nanopowders were synthesized by a low-temperature soft chemical method, and then the BaTiO3/La2O3 composite ceramics were prepared. X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to characterize the prepared powders and ceramics. And the dielectric properties of the BaTiO3/La2O3 composite ceramics were studied. The results revealed that some of La3+ ions dissolved into the lattice of BaTiO3 at Ba-site and the rest remained at grain boundaries in oxide form of La2O3. With the content of La2O3 increasing, Curie peak of the BaTiO3/La2O3 composite ceramics moved to a lower temperature, and the dielectric loss of the BaTiO3/La2O3 composite ceramics decreased significantly, while the dielectric tunability still kept a relatively high value. The dielectric permittivity and dielectric loss of BaTiO3/La2O3 composite with 10 at.% La2O3 was 227 and 0.0026 at 25 oC and 10 kHz, meanwhile the tunability was up to 17.4% under the electric field of 20 kV/cm.
Preparation and Properties of B4C Ceramic Tapes by Aqueous Tape-Casting
Authors: Liu Wei Liang , Wu Min , Shi Zhong Tao , Xu Zhao Liang , Ruan Jie Ping
Published: March 2016

B4C ceramic tapes were prepared by aqueous tape-casting with boron carbide powders as starting material, deionized water as solvent, polymine (PEI) as dispersant, polyethylene glycol (PEG) as plasticizer, poval (PVA) or gelatin as binders. The influences of pH, dispersant content, kind and content of binder on the stability and rheological property of tape slurries were studied. The experimental results indicated that, when the pH was ranged in 3-4, the slurries with good stability and good rheology could be obtained with 0.8 wt% PEI, 4.0 wt% PVA or 6.5 wt% gelatin. PVA as binder made cast tape with certain strength, and gelatin as binder made cast tape with poor strength.
In Situ Growth of Mullite Whisker Using Different Aluminium Source and Properties of Mullite-Corundum Lightweight Refractory
Authors: Li Xin Hao , Gu Xing Yong , Dong Wei Xia , Luo Ting
Published: March 2016

In-situ growth of mullite whisker from waste coal gangue and different aluminium source mixtures by dry pressing were investigated aiming at the preparation of mullite - corundum lightweight refractory by controlling mullite whisker precursor pseudo particle size and quantity in corundum matrix. The phase composition and microstructure were studied using X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. Apparent porosity and bending strength were also measured. The samples exhibited characteristic alumina and mullite phases. The formation mechanism and influence factors for mullite whiskers materials were discussed. The experimental results showed that the whisker of the obtained sample changed from the accumulated short column to mesh cross acicular whisker shape, and the length to diameter ratio increases. When the aluminium source was aluminium hydroxide, the length to diameter ratio and apparent porosity reached the maximum of 17.6 and the minimum of 2.15%. The bending strength of all the samples was similar, that of the sample prepared by calcined bauxite was the largest (84 MPa), that of the sample prepared by calcined alumina was inferior, and the sample prepared by aluminum hydroxide was the lowest.
Electromagnetic Simulation of Influence of Metamaterial for Magnetic Resonance Imaging at 3T
Authors: Luo Chao , Hu Xiao Qing , Li Chun Lai , Chen Xiao , Zhang Xiao Liang , Liu Sheng Ping , Liu Xin , Zheng Hai Rong , Li Ye , Ji Chun Lin , Luan Lin
Published: March 2016

This paper presents an approach to investigate the influence of metamaterial to radio-frequency (RF) magnetic field in magnetic resonance imaging (MRI) at 3T. The variety of magnetic fields of RF receiving coil was calculated using the commercial electromagnetic simulation software (CST). The simulation results demonstrate that the transmitting and receiving magnetic field (B1+ and B1-) can be enhanced when the metamaterial is inserted into the RF coil, suggesting that the metamaterial has potential in MRI applications at 3T.
YDyxBa2Cu3O7-δ Epitaxial Films Prepared by Chemical Solution Deposition
Authors: Zhang Hong , Zhao Yong , Wang Wen Tao , Zhang Yong , Lei Ming
Published: March 2016

YBa2Cu3O7-δ (YBCO) coated conductors have wide-ranging potential in large scale applications, such as, superconducting maglev trains and superconducting electric cables, but low current carrying capability restrains the practical application of YBCO coated conductors at high temperatures and high magnetic fields. It is crucial to develop YBCO coated conductors with high flux pinning capability. In this paper, epitaxial, dense, smooth and crack-free YDyxBa2Cu3O7-δ (x = 0~0.5) films were prepared on a LaAlO3 (LAO) single crystal substrate via a fluorine-free polymer-assisted metal organic deposition (PA-MOD) method. The effects of Dy addition on the microstructure and superconducting character of YBCO films were investigated. The all films show a strong c-axis orientation and good texture in-plane and out of plane. The Dy addition to the YBCO film hardly affects the critical temperature of YBCO superconductor. The irreversibility fields of YBCO films can be improved with the Dy addition x = 0.5 compared to the pure YBCO film but decreased in the x = 0.3 sample.
Effect of Modified NanoSiO2 Agents on the Morphologies and Performances of UHMWPE Microporous Membrane via Thermally Induced Phase Separation
Authors: Liu Rong , Wang Yan , Zhu Jing , Hu Zu Ming , Yu Jun Rong
Published: March 2016

The effects of Modified NanoSiO2 Agents on the morphology and performance of ultra-high-molecular weight polyethylene (UHMWPE) microporous membranes via thermally induced phase separation were investigated in this work. The NanoSiO2 was surface modified by silane coupling agent KH570 (KH570-NanoSiO2). Differential scanning calorimetry (DSC) and X-Ray Diffraction (XRD) were performed to obtain crystallization of UHMWPE/white oil/ KH570-NanoSiO2 doped system. The morphology and performance of the prepared UHMWPE microporous membranes were characterized with scanning electron microscopy (SEM) and microfiltration experiments. The results showed that the morphology of UHMWPE membrane could be disturbed by KH570-NanoSiO2. Porosity and the rejection of Bovine serum albumin (BSA) of the blend membrane increased with increasing concentration of Modified NanoSiO2, while the water flux slightly decreased.
Exploring the Effect of Molecular Components on Hydrolysis-Resistance Performance and Hydrophilicity of Amphiphilic Poly(Ester-Block-Ether) Copolymers
Authors: Zhang Heng , Jiang Xiao Ze , Pan Xiao Yun , Du Ya , Jones Christopher , Ji Xiao Huan , Wang Jin Fang , Wu Yan , Zhang Yuan Yuan , Sun Bin , Zhu Mei Fang
Published: March 2016

In this study, four poly (ester-block-ether) copolymers were synthesized via the macromolecular transesterification method from different hydrophobic polyester segments prepared from precursors, dimethyl terephthalate (DMT), ethylene glycol (EG), dimethyl-5-hydroxyisophthalate (DHIP) and neopentyl glycol (NPG), and hydrophilic polyether, polyethylene glycol (PEG) or polyetheramine (PEA). The hydrolysis-resistance performance at alkaline condition and hydrophilicity of these four synthetic poly (ester-block-ether) copolymers were characterized by hydrolysis degree and water solubility with Nuclear Magnetic Resonance (NMR) and UV-Absorption Spectroscopy. The results showed that the hydrolysis degree and water solubility of poly (ester-block-ether) copolymers were mainly dominated by the molecular components, the molecular weights of polyester and polyether chains, and the connecting bonds between polyester and hydrophilic chains. The hydrolysis degree was listed from high to low: P(DHIP-NPG)-b-PEA, P(DMT-NPG)-b-PEA, P(DMT-EG)-b-PEA, then P(DMT-EG)-b-PEG. The P(DHIP-NPG)-b-PEA copolymer possesses the best hydrolysis-resistance performance, the hydrolysis degree of which reached only 4.1% after hydrolysis for 14 days, meanwhile, it showed excellent adsorption property on polyester fabrics and the surfaces of the treated fabrics exhibited well hydrophilicity. This study provides a light to explore novel poly (ester-block-ether) copolymers with well hydrolysis-resistance performance and high hydrophilicity through precisely constructing their molecular components, and further extend their potential applications in special auxiliaries and intermediates.
Microstructural Evolution of a Fine-Grained Mg-Y-Nd Alloy during Superplastic Deformation
Authors: Cao Geng Hua , Zhang Da Tong
Published: March 2016

Cast Mg-4.27Y-2.94Nd-0.51Zr (wt.%) alloy was subjected to submerged friction stir processing (SFSP) with at a rotation rate of 600 rpm and a traveling speed of 60 mm min-1. Superplastic behavior of specimens with an average grain size of ~1.3 μm were investigated in the temperature ranges of 683-758 K and the strain rate ranges from 1×10-1 to 4×10-4 s-1. Microstructure characteristics were investigated by optical microscopy, scanning electron microscopy and transmission electron microscopy. The results show that the maximum elongation of 967% was obtained at 733 K and 3×10-3 s-1, the optimal HSRS of 900% achieved at 758 K and 2×10-2 s-1. Grains and second phase particles grew coarser with the increasing temperature or decreasing strain rate. Remarkable grain growth is the main reason that elongations are all significantly decreased when the strain rate decrease from 3×10-3 s-1 to 4×10-4 s-1. Grain boundary sliding is the main mechanism during superplastic deformation.
Thermal Stability and Mechanical Properties of Ti-15-3 Titanium Alloy
Authors: Wang Qing Rui , Li Xing Wu , Sha Ai Xue , Zhao Xin Qing , Zhu Yong Qi
Published: March 2016

The microstructure stability and tensile properties of Ti-15-3 titanium alloy were investigated by aging the alloy at different conditions. The results showed that when the temperature was below 250°C, ω phase precipitates and the tensile strength increased with increasing aging time. Although there were a little of ω phase after aging at 200C for 1000h, Ti-15-3 alloy still presented good strength and ductility. When the aging temperature was 250°C~400°C, ω precipitation or β’ phase separation occurred from β matrix, and finally transformed to α precipitates. The tensile strength increased firstly and then decreased with increasing aging time. When aged at above 400°C, α phase precipitated fast from the alloy, and the strength increased gradually.
Microstructural Evolution during Forging of Ti-6Al-4V Alloy
Authors: Tang Lu Yao , Li Jin Shan , Kou Hong Chao , Yan Xu , Tang Bin , Xue Xiang Yi
Published: March 2016

In this work, a 1600 tons forging machine was employed to conduct forging on the Ti-6Al-4V alloy. The microstructural and textural evolution of forged alloy were investigated by optical microscopy (OM), scanning electron microscopy (SEM), electron backscattered diffraction technique (EBSD) and X-ray diffraction (XRD). The results showed that the lamellar α phase in the Ti-6Al-4V alloy changed into a spherical morphology, and the spheroidization rate and the structure uniformity increased with the increasing forging times. The largest pole density in each incomplete pole figure of the α phase decreased gradually and the high-angle grain boundaries (HAGBs) gradually turned to the low-angle grain boundaries (LAGBs), which indicated that the texture was reduced during the forging process.
Deformation Behavior of Ti-6Al-4V-0.1B Alloy Loaded under High Strain Rates
Authors: Yu Yang , Gao Qi , Mi Xun Jun , Hui Song Xiao , Ye Wen Jun
Published: March 2016

Deformation and fracture behaviors of Ti-6Al-4V-0.1B alloy with Widmanstätten, equiaxed and bimodal microstructures were investigated by Split Hopkinson Pressure Bar (SHPB) under high strain rates of 2100-3200 s-1. The results showed that the equiaxed and bimodal structures had a higher bearing capacity at high strain rates than that of the Widmanstätten structure. With the same microstructure, the increase of strain rate gave rise to an improved uniform plastic deformation. According to an observation on the deformed microstructure, it was found that adiabatic shear behavior was the main reason for failure and fracture of the alloy. The formation and propagation of adiabatic shear bands (ASBs) was the precursor for the failure and fracture of the material. Cavities at the interface between TiB phase and the matrix readily formed due to the uncoordinated deformation, which are not the dominate reason for the failure and fracture.
Characterization of Hot Deformation Behavior of Ti-4.5Al-3V-2Mo-2Fe Titanium Alloy
Authors: Zhu Li Wei , Wang Xin Nan , Fei Yue , Li Jing , Zhu Zhi Shou
Published: March 2016

The hot deformation behavior of Ti-4.5Al-3V-2Mo-2Fe (SP-700) titanium alloy in the temperature range of 650°C~950°C and constant strain rate of 0.01, 0.1, 1 and 10s-1 has been investigated by hot compressive testing on the Gleeble-1500D thermal simulation test machine. The experimental results indicated that the hot deformation behavior of SP-700 alloy was sensitive to the deformation temperature and strain rate. The peak flow stress decreased with the increase of temperature and the decrease of strain rate. The flow curves characteristic under different deformation parameters show significant different. Analysis of the flow stress dependence on strain rate and temperature gives a stress exponent of n as 4.8235 and a deformation activation energy of Q as 410kJ/mol. Based on the dynamic materials model, the processing map is generated, which shows that the most peak efficiency domain appears at the temperature of 725°C~775°C and the strain rate of 0.001 s-1~0.003s-1 with a peak efficiency of 45% at about 750°C/0.01s-1.
Effects of Cold-Rolling Reduction on Microstructure and Mechanical Properties of Ti50Zr30Nb10Ta10 Alloy
Authors: Li Ming Long , Geng Yu Jie , Chen Chen , Pang Shu Jie , Zhang Tao
Published: March 2016

The effects of cold-rolling with different reduction ratios of 70%-90% on the microstructure and mechanical properties of Ti50Zr30Nb10Ta10 alloy were investigated. It was found that the β-Ti phase in this alloy was stable under cold-rolling. With the increase in reduction ratio from 70% to 90%, the microstructure of the alloys evolved from deformed dendrite structure to fiber-like structure. The alloy cold-rolled with the reduction ratio of 70% exhibited optimum mechanical properties of combined high fracture strength of 1012 MPa and plastic strain of 10.1%, which are closely correlated with the dendrite structure of the alloy. It is indicated that the proper cold-rolling is an effective way to improve the mechanical properties of the titanium alloy.
Hot Deformation Behaviors and Microstructure Evolution of SiCp/Al Composites
Authors: Hao Shi Ming , Xie Jing Pei , Li Li Ben , Wang Ai Qin , Wang Wen Yan , Li Ji Wen
Published: March 2016

In order to explore the compressive properties of aluminium matrix composite reinforced with middle content SiC particles, hot compression behavior of 30%SiCp/2024A1 composite was investigated using Gleeble-1500 system at a temperatures range from 350 to 500°C and strain rates from 0.01 to 10 s−1. The associated structural changes were studied by OM, SEM and TEM observations. The results show that the true stress–true strain curves exhibited a peak stress at a small strain (<0.1), after which the flow stresses decreased monotonically until high strains, showing a dynamic flow softening. The stress level decreased with increasing deformation temperature and decreasing strain rate, indicating that the composite is a positive strain rate sensitive material. And therefore there will be a enough time for dynamic recrystallization to complete nucleation and growth at low strain rate and high deformation temperatures.
Structures and Properties of Welding Seams in Nickel-Base Superalloys
Authors: Yu Cao , Zhang Qing Quan , Wu Hui Yun , Wei Ran , Li Ming Yang , Li Zhen Rui
Published: March 2016

Due to the existence of strengthening alloying elements in nickel-base superalloys, welding is quite difficult and the mechanical properties of the welding seam usually decrease significantly compared to the corresponding base materials. In this paper, a study on laser welding of nickel-base superalloys was carried out, and the as-welded samples were treated with mechanical (Rolling) and heat treatment, and the structures and mechanical properties after treatment were investigated. It was found that before any treatment, the fusion line was obviously observed between the welding seam and base materials, and few heat affected zone was found. After rolling treatment, the tensile properties of as-welded samples were close to the base materials. Aging and solid solution treatment can improve the mechanical properties of welding seams significantly. It was indicated that aging treatment could result in the formation of plenty of TiCN precipitates in welding seams, which could be helpful for strengthening the welding seams.
Microstructure and Room Temperature Mechanical Properties of a New Corrosion-Resistant Alloy GH945 for Oil and Gas Applications
Authors: Shi Zhao Xia , Yan Xiao Feng , Duan Chun Hua
Published: March 2016

The microstructure and mechanical properties of a new corrosion-resistant alloy GH945 with high strength for oil and gas production were studied in this paper. The results showed that the main precipitations of GH945 alloy after solution heat treatment and two-stage age hardening treatment were γ′ and γ′′ phase, MC-type carbide, σ phase and M23C6-type carbide. The increase of primary aging temperature not only promoted the precipitation of σ phase and film of continuous M23C6 carbide on the grain boundary, but also led to the coarsening of γ′ and γ′′ phase, which resulted in the decrease of yield strength and impact toughness. Alloy with high Nb content had high strength but low impact toughness. The following heat treatment was preferably used to obtain the combination of high strength and excellent ductility and toughness for GH945 alloy: 1010 °C/70 min, WQ+ 735 °C/9 h + FC to 615 °C/18 h, AC.
Microstructure on Laser In Situ Deposit of TiBx/TiC ReinforcedComposite Coatings
Authors: Liang Jing , Tan Xiao Meng , Wang Cheng Jin , Chen Sui Yuan , Liu Chang Sheng , Qin Jin Cheng
Published: March 2016

In situ synthesized TiBx/TiC reinforced composite coatings were prepared on Ti-6Al-4V substrate by laser in situ deposition using 10B4C-18TiNi-72Ti-6Al-4V (wt. %) powder blends as the feedstock materials. The microstructural analysis of the composites was performed using scanning electron microscope, and phase analysis was done with X-ray diffraction. The results showed that the composite coatings contained long needle TiB, irregular block TiB2 and disperse particles/dendrites TiC, the thick rod phase which was a inlay structure consisted of TiB2 and TiC. These composite reinforced phases were evenly distribution in the (TiNi+Ti2Ni+α–Ti) substrate.
Wear and Corrosion Properties of Crystalline Ni-W Alloy Coatings Prepared by Electrodeposition
Authors: Chen Hao , Ren Xing Run , Zhang Xue Hui , Li Jin Hui
Published: March 2016

Electroplating Ni-W coatings have been prepared on medium carbon steel substrate by using nickel sulphate and sodium tungstate as precursors. The microstructures, phase compositions and performances of the as-prepared coatings were analyzed by SEM, EDS, AFM, XRD, microhardness tester and wear tester, respectively. The surface morphologies after wearing were observed and the wear mechanism was discussed. The corrosion behaviors of the coatings before and after heat-treatments were evaluated by anodic polarization in 3.5% sodium chloride solution. The results show that no obvious flaws could be found in the Ni-W alloy coatings and there was a good bond with the matrix. The microhardness of the coatings increased with increasing heat treatment temperature, reaching its maximum value for heat treatment at 500°C, and then droped down. Wear resistance of the coatings was found to be better than that of 16 Mn steel and the heat treatment improved the hardness and wear resistance. The corrosion resistance of the heat-treated coatings increased with increasing the annealing temperature, and best corrosion resistance could be obtained at the temperature of 500°C.
The Influence of Cylindrical Grinding Medium on Particle Size and Mechanical Properties of TiC Steel Bonded Carbide
Authors: Li Guo Ping , Chen Wen , Sun Li Hui , Sun Hai Shen , Luo Feng Hua
Published: March 2016

Ball milling is an efficient way to produce TiC steel bonded carbide. In addition to the use of alloy steel ball, a certain amount of cylindrical object are used for grinding medium and the content is 0, 15%, 30%, 50%, 100% of the total grinding body, respectively. The results show that average size of particles became smaller with an increase of the content of cylindrical grinding medium. The effect of ball milling is the best when the content of cylindrical grinding medium was 30%. Meanwhile the effect on ball milling with cylindrical grinding medium entirely is not better than that with spherical grinding ball completely. In addition, the ball milled powder is made into experimental samples after mixing glue, granulation, forming, sintering and heat treatment and son on. The particle size of ball milled powder become smaller and the green compact are sintered in lower temperature and kept shorter holding time after adding cylindrical grinding medium in ball mill, which reduces the tendency of growing up of hard phase and improve mechanical properties of the sintered material distinctively.
Investigation on Structures of Aluminum Melts Containing Small Amount of Silicon Element
Authors: Lv Xin Yu , Wang Jun , Shu Da , Sun Bao De
Published: March 2016

Aluminum melt structures play significant roles in process of impurity element eliminations. In order to investigate the aluminum melt structures containing small amount of silicon element, several compositions of aluminum melts were simulated. Molecular dynamics simulation method was employed to investigate the melt structures, concentration profiles and diffusion properties. For purpose of studying structure stability, related calculations were performed by first principles molecular dynamics method. The calculated results suggest that silicon concentration has obvious influence on silicon-silicon radial distribution function; silicon element segregates in local zone in each concentration of aluminum; there is no obvious relationship between silicon concentration and silicon diffusion coefficient; the stable Al-Si phase is formed by substitution lattice point or interstitial space; and position of Fermi energy of the stable structure corresponds to the valley of density of states.
Grain Growth of Polycrystalline AZ31 Mg Alloy Containing Second Phase Particles by Phase Field Simulation
Authors: Wu Yan , Xia Si , Zong Bernie Ya Ping
Published: March 2016

A phase field model has been established to simulate the grain growth of AZ31 magnesium alloy containing spherical particles with different sizes and contents under realistic spatial-temporal scales. The expression term of second phase particles are added into the local free energy density equation, and the simulated results show that the pinning effect of particles on the grain growth is increased when the contents of particles is increasing, which is consistent with the law of Zener pinning. There is a critical particle size to affect the grain growth in the microstructure. If the size of particles is higher than the critical value, the pinning effect of particles for grain growth will be increased with further decreasing the particle size; however the effect goes opposite if the particle size is lower than the critical value.