bluuebunny/crossref_metadata_2025 huggingface dataset:
Severe Embryotoxicity of Artemisinin Derivatives in Experimental Animals, but Possibly Safe in Pregnant Women
Authors: Li Qigui , Weina Peter J.
Published: December 2009

Preclinical studies in rodents have demonstrated that artemisinins, especially injectable artesunate, can induce fetal death and congenital malformations at a low dose range. The embryotoxicity can be induced in those animals only within a narrow window in early embryogenesis. Evidence was presented that the mechanism by which embryotoxicity of artemisinins occurs seems to be limited to fetal erythropoiesis and vasculogenesis/ angiogenesison the very earliest developing red blood cells, causing severe anemia in the embryos with higher drug peak concentrations. However, this embryotoxicity has not been convincingly observed in clinical trials from 1,837 pregnant women, including 176 patients in the first trimester exposed to an artemisinin agent or artemisinin-based combination therapy (ACT) from 1989 to 2009. In the rodent, the sensitive early red cells are produced synchronously over one day with single or multiple exposures to the drug can result in a high proportion of cell deaths. In contrast, primates required a longer period of treatment of 12 days to induce such embryonic loss. In humans only limited information is available about this stage of red cell development; however, it is known to take place over a longer time period, and it may well be that a limited period of treatment of 2 to 3 days for malaria would not produce serious toxic effects. In addition, current oral intake, the most commonly used route of administration in pregnant women with an ACT, results in lower peak concentration and shorter exposure time of artemisinins that demonstrated that such a concentration–course profile is unlikely to induce the embryotoxicity. When relating the animal and human toxicity of artemisinins, the different drug sensitive period and pharmacokinetic profiles as reviewed in the present report may provide a great margin of safety in the pregnant women.
Mitochondrial Drugs for Alzheimer Disease
Authors: Bonda David  J. , Wang Xinglong , Gustaw-Rothenberg Katarzyna  A. , Perry George , Smith Mark  A. , Zhu Xiongwei
Published: December 2009

Therapeutic strategies for Alzheimer disease (AD) have yet to offer a diseasemodifying effect to stop the debilitating progression of neurodegeneration and cognitive decline. Rather, treatments thus far are limited to agents that slow disease progression without halting it, and although much work towards a cure is underway, a greater understanding of disease etiology is certainly necessary for any such achievement. Mitochondria, as the centers of cellular metabolic activity and the primary generators of reactive oxidative species in the cell, received particular attention especially given that mitochondrial defects are known to contribute to cellular damage. Furthermore, as oxidative stress has come to the forefront of AD as a causal theory, and as mitochondrial damage is known to precede much of the hallmark pathologies of AD, it seems increasingly apparent that this metabolic organelle is ultimately responsible for much, if not all of disease pathogenesis. In this review, we review the role of neuronal mitochondria in the pathogenesis of AD and critically assess treatment strategies that utilize this upstream access point as a method for disease prevention. We suspect that, with a revived focus on mitochondrial repair and protection, an effective and realistic therapeutic agent can be successfully developed.
An Efficient Pipeline Wavefront Phase Recovery for the CAFADIS Camera for Extremely Large Telescopes
Authors: Magdaleno Eduardo , Rodríguez Manuel , Rodríguez-Ramos José Manuel
Published: December 2009

In this paper we show a fast, specialized hardware implementation of the wavefront phase recovery algorithm using the CAFADIS camera. The CAFADIS camera is a new plenoptic sensor patented by the Universidad de La Laguna (Canary Islands, Spain): international patent PCT/ES2007/000046 (WIPO publication number WO/2007/082975). It can simultaneously measure the wavefront phase and the distance to the light source in a real-time process. The pipeline algorithm is implemented using Field Programmable Gate Arrays (FPGA). These devices present architecture capable of handling the sensor output stream using a massively parallel approach and they are efficient enough to resolve several Adaptive Optics (AO) problems in Extremely Large Telescopes (ELTs) in terms of processing time requirements. The FPGA implementation of the wavefront phase recovery algorithm using the CAFADIS camera is based on the very fast computation of two dimensional fast Fourier Transforms (FFTs). Thus we have carried out a comparison between our very novel FPGA 2D-FFTa and other implementations.
ISFET Based Microsensors for Environmental Monitoring
Authors: Jimenez-Jorquera Cecilia , Orozco Jahir , Baldi Antoni
Published: December 2009

The use of microsensors for in-field monitoring of environmental parameters is gaining interest due to their advantages over conventional sensors. Among them microsensors based on semiconductor technology offer additional advantages such as small size, robustness, low output impedance and rapid response. Besides, the technology used allows integration of circuitry and multiple sensors in the same substrate and accordingly they can be implemented in compact probes for particular applications e.g., in situ monitoring and/or on-line measurements. In the field of microsensors for environmental applications, Ion Selective Field Effect Transistors (ISFETs) have a special interest. They are particularly helpful for measuring pH and other ions in small volumes and they can be integrated in compact flow cells for continuous measurements. In this paper the technologies used to fabricate ISFETs and a review of the role of ISFETs in the environmental field are presented.
RAC-Multi: Reader Anti-Collision Algorithm for Multichannel Mobile RFID Networks
Authors: Shin Kwangcheol , Song Wonil
Published: December 2009

At present, RFID is installed on mobile devices such as mobile phones or PDAs and provides a means to obtain information about objects equipped with an RFID tag over a multi-channeled telecommunication networks. To use mobile RFIDs, reader collision problems should be addressed given that readers are continuously moving. Moreover, in a multichannel environment for mobile RFIDs, interference between adjacent channels should be considered. This work first defines a new concept of a reader collision problem between adjacent channels and then suggests a novel reader anti-collision algorithm for RFID readers that use multiple channels. To avoid interference with adjacent channels, the suggested algorithm separates data channels into odd and even numbered channels and allocates odd-numbered channels first to readers. It also sets an unused channel between the control channel and data channels to ensure that control messages and the signal of the adjacent channel experience no interference. Experimental results show that suggested algorithm shows throughput improvements ranging from 29% to 46% for tag identifications compared to the GENTLE reader anti-collision algorithm for multichannel RFID networks.
Structured Mental Model Approach for Analyzing Perception of Risks to Rural Livelihood in Developing Countries
Authors: Binder Claudia R. , Schöll Regina
Published: December 2009

This paper presents the Structural Mental Model Approach aimed at understanding differences in perception between experts and farmers regarding the various livelihood risks farmers are confronted with. The SMMA combines the Sustainable Livelihood Framework with the Mental Model Approach and consists of three steps: (i) definition and weighting of different livelihood capitals; (ii) analysis of livelihood dynamics, and (iii) definition of the social capital by means of agent networks. The results provide a sound basis for the design of sustainable policy interventions such as communication and educational programs which consider farmers’ priorities and viewpoints.
Clostridium perfringens Iota-Toxin: Structure and Function
Authors: Sakurai Jun , Nagahama Masahiro , Oda Masataka , Tsuge Hideaki , Kobayashi Keiko
Published: December 2009

Clostridium perfringens iota-toxin is composed of the enzyme component (Ia) and the binding component (Ib). Ib binds to receptor on targeted cells and translocates Ia into the cytosol of the cells. Ia ADP-ribosylates actin, resulting in cell rounding and death. Comparisons of the deduced amino acid sequence from the gene and three-dimensional structure of Ia with those of ADP-ribosylating toxins (ARTs) suggests that there is striking structural similarity among these toxins. Our objectives are to review the recent advances in the character, structure-function, and the mode of action of iota-toxin by consideration of the findings about ARTs.
Protein Domain Analysis of C. botulinum Type A Neurotoxin and Its Relationship with Other Botulinum Serotypes
Authors: Sharma Shashi K. , Basavanna Uma , Shukla Hem D.
Published: December 2009

Botulinum neurotoxins (BoNTs) are highly potent poisons produced by seven serotypes of Clostridium botulinum. The mechanism of neurotoxin action is a multistep process which leads to the cleavage of one of three different SNARE proteins essential for synaptic vesicle fusion and transmission of the nerve signals to muscles: synaptobrevin, syntaxin, or SNAP-25. In order to understand the precise mechanism of neurotoxin in a host, the domain structure of the neurotoxin was analyzed among different serotypes of C. botulinum. The results indicate that neurotoxins type A, C, D, E and F contain a coiled-coil domain while types B and type G neurotoxin do not. Interestingly, phylogenetic analysis based on neurotoxin sequences has further confirmed that serotypes B and G are closely related. These results suggest that neurotoxin has multi-domain structure, and coiled-coil domain plays an important role in oligomerisation of the neurotoxin. Domain analysis may help to identify effective antibodies to treat Botulinum toxin intoxication.
H5N1 Virus Evolution in Europe—An Updated Overview
Authors: Cattoli Giovanni , Fusaro Alice , Monne Isabella , Capua Ilaria
Published: December 2009

Since its emergence in South East Asia in 2003, Highly Pathogenic Avian Influenza (HPAI) A/H5N1 has reportedly caused outbreaks in poultry and/or wild birds in 62 countries, of which 24 were in Europe. Interestingly, out of the many genetic clades circulating in Asia, the westward spread of HPAI A/H5N1 to Central Asia, the Middle East, Europe and Africa was dominated by one single clade, namely clade 2.2. In this paper, we review and update through phylogenetic and gene migrational analysis the information concerning the evolution and the molecular epidemiology of HPAI A/H5N1 on the European continent.
Water-Activated Bacterial Cellulose-Based Electrorheological Fluids and Electromechanical Response of Artificial Muscle Based on Electrorheological Fluids and Siloxane Gel
Authors: Xu Nai , Jia De Min
Published: December 2009

Electrorheological (ER) characteristics of ER fluids (ERF) containing bacterial cellulose (BC) particles in silicone oil was investigated as a function of particle water content, DC electric field strength and particle concentration. It was found that the existence of water in BC particles strongly influenced the performance of water-activated ERF based on BC particles. Around 8.8 wt% water, yield stress reached its maximum valve of 1118 Pa after which it decreased with increasing water content. At the same water content, yield stress increased linearly with increasing in either electric field strength or particle concentration. The ERF based on BC particles was introduced into the poly (dimethylsiloxane) (PDMS) gels to prepare electric field sensitive composite gel. Electric fields were applied to these composite gels using flexible electrodes. Compressions of these gels with varying PDMS/ERF ratios were confirmed by the electrode displacement. It was found that 50/50 PDMS/ERF gel exhibited the maximum displacement of 102um at 2 kV/mm electric field.
Fatigue Analysis of the New Stirring Kneader Shafts Using ANSYS
Authors: Xu Ji Qing , Fan Zhi Min
Published: December 2009

The new different-speed mixer is widely used in the production of hydrofluoric acid, amino plastics, synthetic rubber and so on. The stirring kneader shafts are the key parts of different-speed mixer, and the problems about strength of shafts were very important. The finite element model of the stirring kneader shaft was built based on ANSYS software in this paper. The ANSYS software was adopted for the static strength analysis of the stirring kneader shaft, and the dangerous points were found. Then these data were used to perform a fatigue analysis by ANSYS-Fatigue. The results showed that the new stirring kneader shaft was able to meet fatigue requirement during the whole service life.
Numerical Simulation of Temperature Field in Barrel of Injection Molding Machine during Induction Heating Process Based on ANSYS Software
Authors: Chang Shi Jia , Xie Peng Cheng , He Xue Tao , Yang Wei Min
Published: December 2009

A finite element model of temperature field coupled with electromagnetic field has been established based on induction heating theory including Maxwell’s equations, thermal conductivity differential equation and magnetic vector potential to simulate the induction heating process of barrel of injection molding machine by universal ANSYS software, and to obtain temperature field of the barrel related to time variation. The coupled thermal and electromagnetic field problem taking account of nonlinear materials characteristics related to temperature was discussed. The induction heating process of barrel was analyzed, and the temperature distribution and its variation with time were obtained.
Comparison of Human Articular Cartilage and Polyvinyl Alcohol Hydrogel as Artificial Cartilage in Microstructure Analysis and Unconfined Compression
Authors: Li Feng , Su Yong Lin , Shi Du Fang , Wang Cheng Tao
Published: December 2009

Many biomaterials have been developed to replace articular cartilage. One of these materials, polyvinyl alcohol (PVA) hydrogel is proposed to be used as artificial cartilage in joint replacement. To better understand the differences between human articular cartilage and PVA hydrogel, microstructure analysis and unconfined compression were developed. In microstructure analysis, the surface of articular cartilage was smooth and free from any significant morphological features. Some small holes were found in the surface and cross-section of PVA hydrogel. The porous structure of PVA hydrogel was observed clearly by Environmental scanning electron microscopy (ESEM). In unconfined compression tests, the compression modulus of articular cartilage was higher than that of PVA hydrogel. In the creep tests, the strain value of articular cartilage was lower than that of PVA hydrogel all the time. It is indicated that the microstructure of each material has a great influence on their biphasic property which related to their mechanical behavior.
Virtual Prototype Design System of Tripod Universal Joints
Authors: Chang De Gong , Yang Fu Qin , Chen Hao
Published: December 2009

Due to the technical factors such as analytical design and virtual prototyping, the simple but representative sliding bar was chosen in this paper and its mathematical model of working contour was established by using the analytic method. And then, the parameterized model and VRML file structural drawing of sliding bar were given by using double extrusion method. It was proved that the components of the tripod universal joint were formed easily by using the double extrusion method based on Extrusion nodes. In addition, the tripod universal joint assembly model was also accomplished by using Inline nodes and bottom-up assembling method.
The Optimal Design of Oscillating Oil Cylinder Mechanism of Tire Building Machine
Authors: Meng Zhao Ming , Qiao Ya Bo , Fan Zhi Min
Published: December 2009

according to the poor quality situation that tire building machine presses tire in current market, the thesis analyses the reasons that press roll presses tire uncompactedly and tire layer has bubbles in the process of tire building machine repression. A new design method that is the optimal design of oscillating oil cylinder mechanism of tire building machine is presented. In the premise of meeting the movement performance of mechanism, it not only can maintain that the pressing roll fits in the best pressure, but also enables wave motion of fitting tire pressure in the allowable scope when mechanism is in the dynamic movement. The article cites examples of the design, demonstrates the superiority of the new design method fully.
Analysis of Melting Process and Numerical Simulation of Pure UHMW-PE Pipe Based on Molding in Barrel Technology
Authors: Qin Jian Hua , Liu Chun Hui , Gao Wen Feng , Yu Chuan Hao
Published: December 2009

Ultra High Molecular Weight Polyethylene(UHMW-PE) pipe is a kind of pipe of thermoplastic engineering plastic with excellent comprehensive performance, but the difficulty in molding is a technical bottleneck which has already affected the extensive application of pipe of pure UHMW-PE. Molding in barrel on the Single screw extruder is a new technology of extrusion molding method, which can continuously carry out pipe of pure UHMW-PE, the most significant advantages of the technology are as follows: under the circumstances of no need to feed any additives in the whole forming process, it can continuously carry out pipe of pure UHMW-PE, and the extrusion molding speed of it is up to 12 m/h above. During the process of it based on molding in barrel technology, one of the main factors influencing to whether UHMW-PE pipe can be successfully molded or not is whether the melting process of raw material is adequate and appropriate or not. This article will elaborate melting characteristics of raw material of UHMW-PE, establishment of mathematical model of melting process, and numerical simulation of melting process, which belong to the forming process of molding in barrel, and will provide a theoretical basis for correctly designing the structure of single screw extruder and temperature control system of single-screw extruder, based on Molding in Barrel Technology.
Preparation and Thermal Properties of Phosphorus-Containing Copolyester Nanocomposites with Carbon Nanotube
Authors: Zhao Qing Fu , Sun Shi Yuan , Jiang Xiao Wei , Qu Ming Hai , Wang Yu Zhong
Published: December 2009

Flame retardant nanocomposites were synthesized by melt-blending phosphorus-containing copolymer (PET-co-DDP) with multi-wall carbon nanotubes. PET-co-DDP was copolymerized with terephthalic acid (TPA), ethylene glycol (EG) and 9, 10-dihydro-10[2, 3-di-(hydroxy carbonyl)propyl]-10-phosphaphenanthrene-10-oxide (DDP). The structure of the nanocomposites was characterized by scan electron microscopy (SEM). Fire property measurements by cone calorimeter revealed that the incorporation of multi wall carbon nanotubes into PET-co-DDP significantly reduced the peak heat release rates compared with the PET-co-DDP. The thermal properties of the nanocomposites were investigated by thermogravimetric analysis (TGA). It was found that the thermal stability of copolyester was improved by the addition of the multi-wall carbon nanotubes. Char formation is the main factor for these improvements. The flame retardant performance was achieved through the formation of a relatively uniform network-structured floccule layer covering the entire sample surface without any cracks or gaps. This layer re-emitted much of the incident radiation back into the gas phase from its hot surface.
Three Dimension Fluid Field of Mixer with Synchronous Rotors
Authors: Bian Hui Guang , Fu Cui Wen , Zhang De Wei
Published: December 2009

The flow field analyzed method about mixer flow in chamber has been introduced, Synchronous rotor three dimension flow field simulation rubber with the Finite Element Analysis is reported. The physical and three dimension Finite Element Method models for synchronous rotors flow field has been built for the first time. Isothermal flow field simulation with synchronous rotor has been made, the pressure field, velocity field and viscosity field had been obtained from numerical simulation. The results showed flow field’s change rule in a circle clearly, which are useful to improve mixer rotor’s structure.
Preparation and Properties Study on the Composites of Polypropylene and Polyphenylene Sulfide Filled by Modified Molybdenum Disulfide
Authors: Zhang Jian Qiang , Feng Hui Xia , Qiu Jian Hui
Published: December 2009

The wet surface modification process were used in this work to get the well lipophilic molybdenum disulfide (MoS2) powders and the modified MoS2 were filled into the polyphenylene sulfide (PPS) and polypropylene (PP) powders with different proportions to make polymeric based composites through hot-press molding equipment. The Fourier transform infrared spectrometer (FT-IR) analysis showed that the modification agents of stearic acid (SA), orγ-Methacryloxypropyl trimethoxy silane(KH570 or A-174), could react with the adsorption hydroxyl(−OH) of the MoS2 powders and finally form chemical coatings, the SA could form a layer of physics wrap too. The powder X-ray diffraction (XRD) analysis reveled that the SA or KH570 could not change the laminated structure of MoS2. The wearability testing showed that the composites filled by modified MoS2 owned the better wearable performances than the filled not one. From minimum to maximum, the wear mass rates of SA/MoS2/PP/PPS, KH570/MoS2/PP/PPS, PP/PPS were 0.7216, 5.4187 and 7.3198 percent in turns. Scanning electronic microscope (SEM) analysis showed the surface modification could uniformize the modified MoS2 to disperse in the polymeric based composites, and also reflect the abrasion mechanism which the particles and the adhering wear modes could all make the mass loss of the testing samples and they coexisted and could transform each other, the former would produce higher loss rates than the later and their leader status would gradually change from the particles wear to the adhering wear during the course of wearing-resisting tests.
Preparation and Electrical Conductivity of Composites of PA66 Filled with Carbon Nanotubes
Authors: Tsai Fang Chang , Li Peng , Shang Xiao Peng , Ma Ning , Tsai Lung Chang , Yeh Jen Taut
Published: December 2009

An investigation of the blend of PA66 / organic modified multi-wall carbon nanotubes (MWNT) is reported. The MWNT was carboxylated in a sulfuric and nitric mixed acid under ultrasonic vibration. In fact, the electrical conductivity of these composites is analyzed. The MWNT-filled PA66 shows percolation point of the electrical conductivity at low filler loadings (0.5-12wt%). Presumably, the carboxylated MWNT was reacted with PA66. The neat MWNT, carboxlyated MWNT, and PA66/MWNT composites were characterized with FTIR, polarity, DSC, and electrical conductivity.
Characterization of Amorphous Silicon Thin Films Deposited on Upilex-s Polyimide Substrates for Application in Flexible Solar Cells
Authors: Li Ying Ge , Du Dong Xing
Published: December 2009

Upilex-s [poly(biphenyl dianhydride-p-phenylene diamine)] polyimide have been widely employed in the area of flexible electronics. For its potential application on fabricating flexible solar cells, the optical properties of Upilex-s are measured in this paper. Intrinsic hydrogenated amorphous silicon layers are then deposited on Upilex-s substrates at temperatures 100°C and 180°C by plasma enhanced chemical vapor deposition (PECVD) system. As an comparison, intrinsic a-Si:H layers are also fabricated on glass substrate of Corning2000. Both layers on flexible and rigid substrates are thoroughly characterized by activation energy and dark conductivity measurements. It can be concluded that the intrinsic layer on Upilex-s has favorable properties and could be a competitive candidate as substrate materials of flexible solar cells.
Biodegradable Poly(Lactic Acid)/Organic-Montmorillonite Nanocomposites: Preparation and Characterization
Authors: Chen Na Li , Feng Hui Xia , Luo He Ming , Zhao Dan , Qiu Jian Hui
Published: December 2009

In this work, the biodegradable poly(lactic acid) (PLA)/organic-montmorillonite (O-MMT) nanocomposites were successfully prepared by the in situ polymerization intercalation process of D,L-lactide with organically-modified montmorillonite which was first treated by Cu cations and second treated by n-hexadecyl trimethylammonium bromide (CTAB) cations. O-MMT was characterized by FT-IR and XRD, the results showed that Cu cations and CTAB cations had been inserted to the interlayer of MMT, and the interlayer spacing of CTAB-Cu-MMT (O-MMT) increased by 1.829nm. The biodegradable PLA/O-MMT nanocomposites were characterized by XRD, SEM, FT-IR, TG, and the results showed that silicate layers were intercalated into the PLA matrix and the biodegradable PLA/O-MMT nanocomposites were of two different types: intercalated nanocomposites and exfoliated nanocomposites. This new nanocomposites frequently exhibited remarkable improvements when compared with the neat PLA matrix. Improvements could include increased heat distortion temperature, an increase in the biodegradability rate of biodegradable polymers.
The Study on Buckling Deformation of Composite Pressure Vessel Based on Acoustic Emission Signals
Authors: Hu Zhao Hui , Liu Hong Jun , Wang Rong Guo , He Xiao Dong , Ma Li
Published: December 2009

The buckling deformation of the liner within composite pressure vessel is investigated using acoustic emission (AE) signals. The liner will fail with buckling deformation which is casued by compression stress induced by deformation compatibility beween composite layer and the liner. The experimental results show that these high-amplitude signals higher than 80dB are responsible for the buckling deformation of the liner within composite pressure vessel during unloading process.
Research on the Thermal Oxidation and Ultraviolet Radiation Aging of Nano-ZnO/NR Composite
Authors: Zhuang Tao , Shan Ti Kun , Zhou Li Ling
Published: December 2009

To study the effection of nano-ZnO on thermal oxidative aging and ultraviolet radiation aging of NR, and the mechanisms of thermal oxidation aging and ultraviolet radiation aging of nano ZnO in NR were explained by TG and stress relaxation and ultraviolet analysis. The results revealed that nano-ZnO can improve the anti-thermal oxidation aging and anti-ultraviolet radiation aging of NR, and the protective effect improves with the increase dose of nano-ZnO.
Synthesis and Property of Photo- and Temperature- Dual-Responsive Amphiphilic Block Copolymers
Authors: Tang Xin De , Han Nian Feng , Zhou De Jie
Published: December 2009

Photo- and temperature-responsive amphiphilic block copolymers, poly(ethylene glycol)-b-poly{(N-isopropylacrylamide-co-6-[4-(4-methoxyphenylazo)phenoxy]hexyl methacrylate), denoed as PEO-b-P(NIPAM-co-MAZO), were designed and synthesized by atom transfer radical polymerization (ATRP). The macroinitiator based on poly(ethylene glycol) (PEG, Mn = 2000 Da) was utilized to initiate the copolymerization of N-isopropylacrylamide (NIPAM) and 6-[4-(4-methoxyphenylazo)phenoxy]hexyl methacrylate (MAZO). The resultant copolymers, combining photo-responsive moieties with thermal-responsive moieties, possess photo- and temperature- dual-responsive property, among of which, PNIPAM shows lower critical solution temperature (LCST) and PMAZO exhibits reversible trans-cis isomerization under UV/vis irradiation. In selective solution they can form selective micro-tunnel with excellent controlled release, and can be used as drug carrier and controllable membrane.
Research on the Adjustable LAVAL Nozzle during Pneumatic Conveying
Authors: Jiao Dong Mei
Published: December 2009

The relationship between the input and output (displacement of adjusting lever and air flow) of adjustable LAVAL nozzle is deduced. In the pneumatic conveying condition, finite element analysis to adjustable LAVAL nozzle is simulated, and its steady-flow effect is proved. Experiments show the adjustable LAVAL nozzle is energy-saving, can improve the quality of conveyed material, and reduce percentage of damage.
Preparation of Anion Modified Montmorillonite-Polystyrene Nanocomposite by Suspension Polymerization
Authors: Wang Yi , Feng Hui Xia , Qiu Jian Hui
Published: December 2009

To ensure good compatibility between polymer and montmorillonite (MMT), three types organophilic-MMT were prepared and the influence of modifying agent style on the modification effect was studied. The results of X-ray diffraction(XRD) show that the modified reagents are all intercalated into the galleries of MMT, which are also proved by patterns of FT-IR and thermogravimetric analysis(TGA), and the spacing of MMT layers increases from 1.23 nm of the pristine MMT to 2.10nm, 3.52nm and 4.14nm for CTAB, SDS and DBS modified MMT respectively. The results also indicate that the d-spacing and exfoliation degree of anionic surfactants inserted MMT is bigger than that of the cationic surfactants treated MMT, which are usually used to preparation polymer layered silicate nanocomposites in literatures. So PS/SDS-MMT and PS/DBS-MMT nanocomposites were prepared by suspension polymerization. The structure of complex were characterized by XRD and no peak can be observed by the spectra, which suggest that the clay platelets have been exfoliated and dispersed in the PS matrix and the both complex are all have exfoliated structure. FT-IR spectrums analysis confirmed the existence of MMT which implied that the layers of silicate was distributing in composites. The results of TGA show that nanocomposites possess exceptionally high thermal stability and the DBS treated composite has higher thermal stability than that of SDS treated.
Polymer Material Application in Cold Insulation Structures
Authors: Luo Xiao Ling , Li Bing
Published: December 2009

The paper proposes that cold insulation property is improved by adding additives and adopting different polymer materials and shows polymer material broad prospects in cold insulation structures. The paper has certain reference value to polymer material performance research.
Dependence of Thermal Conductivity of Carbon Black Filled Rubber on Several Factors
Authors: Song Jun Ping , Ma Lian Xiang
Published: December 2009

Five kinds of carbon black filled natural rubber were prepared, and thermal conductivity was studied considering two factors, which include temperature and volume percent of the filler. It was found that thermal conductivity had relevance to temperature and volume percent of carbon black, besides, structure and specific area of carbon black were also very important influencing factors. Moreover, reuniting phenomenon of nanometer grade of carbon black has much effect on thermal conductivity.
Formula Derivation and Application for Carbon Content versus Heating Temperature in Austenitizing of Cast Iron
Authors: Gong Wen Bang , Xiang Gang Yu
Published: December 2009

In this paper, a formula for the calculation of the carbon content during the austenitizing of cast iron was deduced, considering the effect of silicon content upon the heat-treatment parameter. According to this formula, the carbon content of the austenite at a certain austenization temperature for a cast iron with given components can be easily calculated, and the austenization temperature required to give the expected carbon content in the austenite can also be determined. Moreover, according to the relationship between the austenization temperature Tx and the associated carbon content Cax,, and considering the effect of the silicon content, a diagram showing Cax, Tx and the silicon content during the austenitizing of cast iron was prepared.
A Realistic Method to Describe the Role of Diffusion in Catalyst Design
Authors: Zeynali Mohammad Ebrahim
Published: December 2009

The dehydrogenation of diethylbenzene to divinylbenzene is a catalytic reaction. The catalyst for the dehydrogenation was prepared by co-precipitation of iron and chromium hydroxide from nitrate solution, followed by doping with potassium carbonate and drying. To make available the internal surface area of the catalyst for the reactant, the pores must be of the proper sizes to allow the reactant to diffuse and penetrate inside the catalyst pellets. The prepared catalyst was considered as a model for investigating the role of diffusion in catalyst design.
In this study, different mechanisms of diffusion, such as Knudsen and bulk, were investigated for the case of diethylbenzene diffusion into the catalyst and it was concluded that the pore sizes should be in a range that permits transitional diffusion (both Knudsen and bulk diffusion). The catalyst grain size can be controlled and varied by acting on parameters such as the speed and time of mixing, type of alkali, temperature and pH. Particle size distribution experiments were conducted for different types of alkali and speeds of mixing in order to characterize the catalyst. The effects of the grain size, formed during co-precipitation, upon the pore size distribution of the catalyst pellet which affects the effective diffusivity were discussed. The pore size distribution of the model catalyst was obtained and the effective diffusivities were calculated by numerical integration of the Johanson-Stewart equation.
Structure and Electronic Properties of Evaporated Thin Films of Lead Sulfide
Authors: Ibrahim A.A.
Published: December 2009

Lead sulfide (PbS) thin films were prepared by thermal evaporation onto glass substrates from PbS powder. The structure and DC electrical properties of evaporated PbS thin film sandwich structures with thicknesses (d) up to 600 nm have been investigated. X-ray diffraction studies showed that the films were crystalline, with a preferred orientation in the [111] direction. Capacitance measurements indicated that the films had a relative permittivity of 5.7. Room-temperature current density-voltage (J–V) characteristics revealed ohmic conduction below a transition voltage (Vt) and a power–law dependence with an exponent of ≈ 2 at higher voltages. This behaviour was interpreted in terms of space–charge limited conductivity controlled by an exponential distribution of traps below the conduction band edge. Further evidence for this conduction process was provided by a linear dependence of Vt upon d2. Analysis of the results yielded a room temperature electron concentration no of ≈ (3.9 – 5.4) x 109 m-3.
Preparation of N-Doped ZnO Films by MOCVD
Authors: Kobayashi Kenkichiro , Kobayashi Hiroki , Tomita Yasumasa , Maeda Yasuhisa , Khono Yosiumi
Published: December 2009

Crystalline ZnO films were grown on Y-stabilized ZrO2 substrates heated at 300 - 600 °C in NH3 atmosphere. It is clarified from Fourier transform infrared measurements that N-doped ZnO films grown at 350 and 400 °C contain N-C and Zn-H bonds. In the devices of n-type ZnO/N-doped ZnO/Au, a good rectification characteristic is attained for an N-doped ZnO film deposited at 300°C, whereas a linear current vs. voltage characteristic is seen for a film deposited at 500 °C.
Domain Wall Engineering in Lead-Free Piezoelectric Materials
Authors: Wada Satoshi , Pulpan Petr
Published: December 2009

Grain-oriented barium titanate (BaTiO3, BT) ceramics were prepared by a templated grain growth (TGG) method using [110]-oriented BT platelike particles as a template and hydrothermal BT sphere particles with different particle sizes as a matrix. The degree of orientation along the [110] direction, F110, was measured using an X-ray diffraction (XRD) pattern by the Lotgering method. To obtain both a high density and a high F110, the preparation conditions were optimized as functions of matrix particle size, volume fraction of the template to the matrix, and sintering temperature. As for the results, BT grain-oriented ceramics with a high density of more than 96 % were successfully prepared despite various F110 values from 0 to 98 %. Scanning electron microscopy (SEM) revealed that their average grain sizes were always 75 µm despite various F110 values and there were no anisotropic microstructures. These grain-oriented BT ceramics were poled at 100 °C, and their piezoelectric constants d33 was measured. As for the results, the d33 values increased with increasing F110 values, and at around an F110 of 85 %, d33 reached a maximum of 788 pC/N.
Monte Carlo Investigation of Ferroelectric Properties in Thin Films
Authors: Laosiritaworn Yongyut
Published: December 2009

In this work, the ferroelectric hysteresis in thin films was investigated with Monte Carlo simulation using the DIFFOUR Hamiltonian and the Metropolis algorithm. The field frequency, the filed amplitude and the thickness dependence of hysteresis properties were found. For instance, at high enough field, the area increases, maintains and reduces with increasing frequency. However, with increasing the film’s thickness, the area increases over the whole considered frequencies, and the frequency at maximum area shifts to a lower frequency due to the stronger ferroelectric coupling in thicker films. This strongly indicates the thickness dependence of the ferroelectric hysteresis. In addition, the power law scaling relation between the hysteresis properties and input parameters, which are the film’s thickness and the field parameters, were proposed. The scaling exponents were compared and discussed with previous investigations on thin ferroelectric films.
Effect of Zr-Addition on Electric Degradation Characteristics of ZnO Varistors
Authors: Akiyama Yuji , Takada Masayuki , Fukumori Ai , Sato Yuuki , Yoshikado Shinzo
Published: December 2009

ZnO varistors of the excellent tolerance characteristics for electrical degradation were made by adding Bi2O3-MnO2-Co3O4-Cr2O3-SiO2-Sb2O3-NiO in ZnO. The tolerance characteristics for electrical degradation were evaluated by changing amount of ZrO2-additive. The evaluation methods are voltage-current characteristics, X-ray diffraction, scanning electron microscope, and energy dispersion X-ray spectroscopy. Monoclinic and tetragonal ZrO2 and the compounds originated in Zr were observed at both grain boundaries and triple points. Moreover, the compounds originated in both Zr and Sb improved the tolerance characteristics for electrical degradation. On the other hand, especially monoclinic ZrO2 deteriorated the tolerance characteristics for electrical degradation. It is one key factor of the improvements of the tolerance characteristics for electrical degradation that the mobility of oxide ions or interstitial Zn2+ ions was hindered by forming the compounds contained Zr, Sb, Si, and, Bi atoms.
Piezoelectric Properties of c-Axis-Oriented (Sr,Ca)2NaNb5O15 Piezoelectric Ceramics with Single-Plate Type and Multilayered Type Fabricated Using Crystal-Oriented Sheet Forming
Authors: Shimizu Hiroyuki , Doshida Yutaka , Tanaka Satoshi , Uematsu Keizo
Published: December 2009

Recently, we have developed crystal-oriented sheet forming (COSF) process from green sheet process and high-magnetic-field method. We formed c-axis-oriented (Sr,Ca)2NaNb5O15 (SCNN) sheets by the COSF process, and succeeded in realizing c-axis-oriented single-plate type piezoelectric ceramics (O-SP) and c-axis-oriented multilayered type piezoelectric ceramics (O-MLPC) for SCNN. From the measurement results of displacement induced by electric field, it was clarified that effective d33 of the O-SP was 210~240 pm/V. This value was about 3 times larger than that of the randomly oriented single-plate type, which was 70% of that of single crystal. Moreover, it was confirmed that O-MLPC indicated displacements 2.5 times as large as that of the conventional multilayer piezoelectric ceramics. In this study, we clarified that piezoelectric properties in bulk and multilayer structure can be drastically enhanced using the COSF process.
Stress Dependence of Dielectric Properties in Relaxor Ferroelectrics: Monte Carlo Investigation
Authors: Laosiritaworn Yongyut , Yimnirun Rattikorn , Guo Ruyan , Bhalla A.S.
Published: December 2009

In this work, we used Monte Carlo simulation to investigate the uniaxial stress dependence of the relaxor dielectric properties. The Metropolis algorithm and the spin glass type interaction were used in updating the local polarizations (representing the polar nano-regions). The exchange interaction in the spin glass Hamiltonian was assumed to be stress dependent via the strain. From the results, the frequency dependence of the dielectric permittivity were found, where, at high enough stress, the dielectric permittivity decreases with increasing stresses in qualitatively good agreement with experiments. In addition, from the modified Curie-Weiss law, all ’s stay close to 2. Therefore, this implies the frequency dispersion universality of the relaxor system under loading conditions.
Properties of Barium Stannate Titanate with Boron Oxide Addition
Authors: Tawichai Nattaya , Eitssayeam Sukum , Intatha Uraiwan , Pengpat Kamonpan , Rujijanagul Gobwute
Published: December 2009

In this study, barium stannate titanate ceramics with an addition of boron oxide were synthesized via a solid-state sintering method. The effect of sintering aid on electrical and mechanical properties of barium stannate titanate ceramics was investigated. It was found that, the ceramic with 2 wt% boron oxide showed the lowest porosity and the highest dielectric constant of ~ 13700 at room temperature. In addition, an increase in the boron oxide content was observed to enhance the hardness of the ceramics. These results may be helpful in the multilayer capacitor applications.
Effect of Compressive Stress on Ferroelectric Aging Behavior of Hybrid-Doped Fe3+/Nb5+ BaTiO3 Ceramics
Authors: Prasertpalichat Sasiporn , Unruan Muangjai , Sareein Thanapong , Tangsritrakul Jirapa , Ngamjarurojana Athipong , Ananta Supon , Yimnirun Rattikorn
Published: December 2009

Apart from aging effect, barium titanate ceramics usually subjected to the mechanical loading when it is used in electronic device. Thus, it is very interesting to investigate the influence of various compressive stresses on ferroelectric aging behavior of Ba(Ti0.99-xFe0.01Nbx)O3 , x=0.005-0.015. In this study, the P-E hysteresis loops were observed by using compressometer in conjunction with a modified Sawyer-Tower circuit. The stress level was varied from 0 to 185 MPa. The results showed that the dissipation energy, saturation polarization (Psat), remnant polarization (Pr) and the coercive field (Ec) decreased with increasing of stress. The aging behavior was still observed in acceptor-dominant of hybrid doped ceramics. The aging was also enhanced under application of the external stress. The explanation based on the defect-dipole and domain-reorientation processes was discussed.
Durability Improvement of Optical H2 Gas Sensor Using Pd Thin Film on Sputter-Etched Glass Substrate
Authors: Yakushiji Yuji , Kuroki Yuichiro , Okamoto Tomoichiro , Takata Masasuke
Published: December 2009

A glass substrate was sputter-etched by R. F. magnetron sputtering at the powers of 100 or 200 W for 60 min in Ar gas. Pd thin film as a sensing agent of hydrogen (H2) was deposited on the glass substrate. The durability of the sensor was evaluated during hydrogen absorption-desorption cycles. The Pd thin film on the glass substrate without sputter etching peeled off after dozens of the cycles. However, the Pd thin film on sputter-etched glass substrate didn’t peel off. The contact angle of water on the glass substrate with sputter etching was smaller than that without sputter etching, suggesting that the surface energy of the substrate was increased by employing the sputter etching process. The improvement of durability for the optical hydrogen sensor using sputter etched substrate was related to the increase of surface energy induced by the sputter etching.
Triboluminescence of Highly Oriented SrAl2O4:Eu Film and its Potential Role as a Stress Indicator
Authors: Fu Xiao Yan , Yamada Hiroshi , Xu Chao Nan
Published: December 2009

Highly oriented SrAl2O4:Eu film had been deposited on a quartz glass using the RF sputtering method. The fabricated film displayed fiber-texture with the (031) orientation. The surface of the film was smooth and compact. In addition, under the UV excitation, the film emitted green light. After the removal of UV excitation, a long afterglow phenomenon could be observed from this film. The important point of this study was that SAOE film displays strong adhesion and high green triboluminescence (Tribo-L). Such properties made the films be a potential candidate as stress indicators.
Development of Intermediate-Temperature Solid Oxide Fuel Cells Using Doped Lanthanum Gallate Electrolyte
Authors: Eto Hiroyuki , Akbay Taner , Akikusa Jun , Uozumi Gakuji , Chitose Norihisa , Inagaki Toru , Ishihara Tatsumi
Published: December 2009

Intermediate-temperature(IT) solid oxide fuel cells(SOFCs) were developed using lanthanum gallate electrolyte, samarium cobaltite cathode and the cermet anode of nickel and ceria. High efficiency operation below 800°C was enabled using planar disk type cells with unique seal less stack design. The first 10 kW-class combined heat and power (CHP) system provided AC output power of 10 kW with electrical and overall efficiency of 41 and 82 %HHV, respectively. Optimization of cell-stack components to increase the output power density is in progress.
Luminescence Properties of Y(P,V)O4 Synthesized by Microwave Heating
Authors: Toda Ayano , Toda Kenji , Ishigaki Tadashi , Uematsu Kazuyuki , Sato Mineo
Published: December 2009

Eu3+ doped and undoped Y(P,V)O4 phosphors were prepared using multi-mode and single-mode microwave oven operated at 2.45 GHz. In the case of the microwave heating method, the phosphor particles were non-aggregated. A homogeneous distribution of Eu ion was observed in the microwave synthesis. No sintering behavior found in the microwave heating may be attributed to a quite shorter heating time. The Eu3+ doped sample synthesized by microwave heating showed intense red emission under UV excitation.
Dynamic Hysteresis Scaling in BaTiO3 Bulk Ceramics
Authors: Wongdamnern Natthapong , Ngamjarurojana Athipong , Ananta Supon , Laosiritaworn Yongyut , Yimnirun Rattikorn
Published: December 2009

The scaling behavior of the dynamic hysteresis of ferroelectric BaTiO3 bulk ceramics was investigated. Two sets of the scaling relation of hysteresis area  against frequency f and field amplitude E0 were clearly established. Approximately, above the coercive field, the scaling took a form of   f -0.23E00.87. On the other hand, the scaling in the form of   f -0.36E03.64 was obtained under a sub-coercive field condition. While these scaling relations were generally comparable to previously reported ones, it was found that the f- and E0 exponents clearly depended on E0 and f, respectively.
Dynamics of Central Peaks in the Brillouin Scattering Spectra of Relaxor Ferroelectrics
Authors: Shabbir Ghulam , Kojima Seiji
Published: December 2009

High-resolution Brillouin scattering technique was applied to study the dynamics of central peaks (CPs) in two relaxor ferroelectric systems, PLZT-x/65/35 ceramics and PMN-33%PT [001] single crystals, respectively. It was found that CPs appear very close to an intermediate temperature, Td, for both type of specimens. The temperature dependence of CPs was attributed to the appearance and subsequent growth of polar nanoregions (PNRs) intrinsic to relaxor materials.
Dielectric Properties of 0-3 Lead Magnesium Niobate Titanate (PMNT)-Ordinary Portland Cement (PC) Composites
Authors: Jaitanong Nittaya , Chaipanich Arnon
Published: December 2009

The dielectric properties of lead magnesium niobate titanate, PMNT and portland cement, PC with x(0.67PMN-0.33PT)-(1-x)(PC) (where x = 0.3, 0.5, 0.7 and 1.0) composites were investigated. The dielectric properties of the 0-3 PMNT-PC composites are measured as function of both room temperatures and frequency. The composites were pressed together and cured in 98%RH curing chamber for 3 days before measurements. The results indicate that the dielectric properties of the PMNT-PC composites increased with increasing PMNT content with dielectric constant, r obtained for the composites with 0.3, 0.5 and 0.7PMNT with dielectric constant, r values of a 136, 414 and 647 respectively.