bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study on Sintering Parameters in Selective Laser Sintering for ABS
Authors: Chen Qing Guo , Zhang Jun Cai
Published: August 2011

Sintering temperature influences on sintering process essentially. Laser power and scanning speed determined sintering temperature. Preheat to powder is beneficial to improve the surface temperature uniformity. Stress concentration of part is various in different layer depth. Therefore, the influence of laser power, scanning speed, thickness of spreading layer and preheat temperature on part quality in selective laser sintering(SLS) are main factors. Based on laser energy in Gaussian distribution and mechanism of SLS, with manufactured specimen pieces by molding machine AFS-450, orthogonal experimental design and analysis of variance are adopted to post-treatment. The prototyping sintering parameters are optimized. The result and solution of the experiment are the preheat temperature of 100°C, the scanning speed of 2000 mm/s, the laser power of 24W, the thickness of single layer of 0.2mm for ABS resin. This work can provide optimized parameters in SLS for ABS resin. It will be of benefit to improve the part dimensional precision and strength.
Tribological Properties of FeCrNi/CBN Composite Coating with Spraying High Velocity Arc
Authors: Liu Cun Xiang , Zhang Jun Hui , Wang Zhao Feng
Published: August 2011

The Tribological properties of FeCrNi/CBN composite coating with spraying high velocity arc is studied. Images and components and cross-section microstructure of coatings are analyzed by the means of SEM, and EDS etc. This research indicates that FeCrNi/CBN composite coatings have typical layered structure characteristic and high bond strength and hardness. Friction coefficient of coatings at room and high temperatures have “Run-up” period. With the increase of temperature, friction coefficient of coatings becomes low and wearing capacity of coatings becomes high. The adding of CBN powder highly improved the wearing capacity of coatings.
FVM Simulation of the Effect of Preventing Ring Structure on Continuous Extrusion Process
Authors: Chen Li , Song Bao Yun , Luan Xiao Dong
Published: August 2011

Continuous extrusion is an advanced process for manufacturing copper bus-bar while preventing ring is an important factor affecting forming. Due to the severe plastic deformation, FE simulation of continuous extrusion extending deforming is inaccurate and inefficient because of frequent remesh. Based on finite volume method (FVM) which can avoid re-mesh effectively, this paper simulates continuous extrusion forming, and analyzes the effect of different preventing ring structure on metal flowing velocity. The results show that: preventing ring with the curve transitional surface is beneficial to metal uniform flowing than that with the plane transitional surface; As radius of preventing ring increases, the metal flow rate of the sides is faster than the middle part; As opening width of preventing ring increases, the dead metal zones become smaller in the middle area.
Analysis of the Simulation Movement in Cigarette Packaging Machine Pusher Device
Authors: Cao Ju Jiang , Tian Xiao Hong , Li Long
Published: August 2011

Researches and analyzes an advanced cigarettes in this paper, with the help of 3d modeling software pro/E image intuitively emulation produce its motion curves, and obtain the displacement, velocity and acceleration curve, Using the mechanism motion and kinematics analysis diagram, the mechanism kinematical process is analyzed which is laid a certain foundation for the further improved cigarette pusher device.
Synthesis and Properties of Poly-Acrylate Emulsion Modified by Organ Silicone
Authors: Liu Yu Xin , Lv Yao Hui , Zhang Shu , Xu Fu Jia , Xu Bin Shi
Published: August 2011

An acrylate emulsion was modified by vinyltriethoxy silane (VTES, trade name A-151) to synthesize the acrylosilane emulsion with high properties. The effect of the amount of A-151 on the properties pf the emulsion was investigated. It found that adding 6 % of A-151, the fraction extensibility of the emulsion film could be increased to 530 % and its water absorption was reduced to 4.2 % while adding 10 % of A-151. On the other side, the particle size and distribution of the emulsion were analyzed by Scanning Electron Microscopy (SEM) and Malvern Particle Size Analyzer (PSA) respectively. The measuring results showed that the particle diameter of the modified emulsion could be between 100 and 700 nanometers, and the properties of the emulsion could be apparently improved by adding A-151 into the system of emulsion polymerization.
Mechanical Properties Analysis of Combined Structure of Suspension Platform of Suspended Access Equipment
Authors: Zheng Xi Jian , Lu Zhen , Liu Ming Da , Zhang Hong
Published: August 2011

Based on the theory of structural mechanics, it has established that a simplified mechanical model of suspension platform of ZLP800 suspended access equipment (SAE) in this paper. Under the two common combinations we could calculate and comparatively analyse deflection of variable stiffness structure of suspension platform. On this basis, 15m span suspension platform module combination was obtained by the enumeration method. Moreover, by deflection calculations of the platform structure in different combinations，we could obtain the best module combination so as to provide a theoretical basis for the design of large span suspension platform.
Experimental and Numerical Studies of the Stress Concentration Factor for Tubular KK-Joints under Axial Loads
Authors: Zhang Yong Tao , Jin Shu Cheng , Yang Yan Hua
Published: August 2011

This paper reports on experimental test and numerical simulation methods that investigate the stress concentration factor and node deformation performance parameters for tubular KK-joints. The numerical analysis can give reference for design schemes of model test, and the bearing characteristics are studied by the model test. Moreover, by comparing the experimental analysis and the finite element simulation results, we discuss the accuracy of numerical analysis method in analyzing the tubular joints stress concentration factor. These can provide a useful reference for the engineering design.
Analysis of the Swelling Effect in Single-Point Diamond Turning
Authors: Zhao Qing Liang , Chen Jun Yun , Luo Jian
Published: August 2011

The swelling effect is an important factor to affect surface generation in SPDT. Face cutting experiments are conducted for copper, aluminum alloy and electroless nickel phosphorus to analyze the swelling effect including the relationship between it and cutting parameters as well as effect of material property. How the material swelling affects surface roughness is also studied in this paper. The results indicate that the swelling effect is influenced by spindle speed and material property more remarkably when compared to feed rate and depth of cut. In addition, a softer and more ductile material will lead to a stronger material recovery, a lower swelling proportion, a lower tool mark height and a smoother machined surface. The result reveals that the swelling effect must be considered when predicting surface roughness in SPDT
Study on Screw Drill Wear when Drilling a New Stainless Steel X02Cr18Ni10MoTiN and Accompanying Phenomena in the Cutting Zone
Authors: Jurko Jozef , Panda Anton
Published: August 2011

The basic hypothesis of this article focuses on the study of cutting tool wear with regard to the elimination of occurrence of poor-quality holes when drilling into new austenitic stainless steel. The problem of drilling holes with diameter D=3 to 10 mm resides in the fact that 20 to 30% of these holes do not comply with prescribed requested requirements. This article presents the results of experiments focusing on the study of the damage process in screw drills with diameter d=6.0 mm when drilling into new austenitic stainless steel X02Cr18Ni10MoTiN. This study also includes an analysis of accompanying phenomena in the cutting zone by measuring some selected parameters. The results of the experiments were compared with Cr18Ni8 steel and then verified when drilling holes into specific products.
Study on Sine-Wave Driving Circuits for EMCCD and its Electron Multiplication Gain
Authors: Zhang Yu Gui , Li Tao , He Zhi Kuan , Han Zhi Xue
Published: August 2011

A sine wave with high frequency and high voltage is a key driving signal for EMCCD to realize electron multiplication. According to signal requirements, DDS technique based on FPGA is employed and then sine-formed code-stream is converted to low-voltage sine wave by a digital/analog device. Afterwards, filtering and high-voltage amplification are used to acquire the sine wave with high frequency and high voltage. For the high-voltage amplification, the transfer function of the circuit system is used to correct the circuit parameters, and at last linear amplified sine wave signal with the functions of phase adjusting and amplitude controlling is obtained. By using the sine-wave to drive the EMCCD, low light level imaging is well acquired by the camera and the relationship between sine-wave amplitude and multiplication gain is tested.
The Realization of Linear Motion Control in Dedicated Digital Control of Marking
Authors: Yang Yue Ting , Chen Xin , Cheng Gao Feng
Published: August 2011

In this paper, using Bresenham line algorithm and uniform acceleration , uniform deceleration control algorithm, Combining compensation control about Z-axis motion on cylindrical surface, the author has writed a complete linear motion control program by integer addition, subtraction, logic operations. The program applies to specific numerical marking machine, you can part the plane, cylindrical surface marking.
Design of Miniaturized DRO Based on Isolated Structure
Authors: Liu Chuan
Published: August 2011

The design and implementation of DRO with isolated structure are presented. The simulation result and measured result show that the DRO with isolated structure is feasible and the indicators are satisfied. Based on the feasible fact, an approach of cavity miniaturization of DRO is provided. The design shows that such method could effectively reduce the spatial dimensions of DRO and achieve the purpose of miniaturization.
The Study of the Preparation of Linolenic Acid-Amylose Complexes and their Oxidation Stability
Authors: Lin Ruo Hui , Wu Ke Gang , Chai Xiang Hua , Zhong Shao Shu
Published: August 2011

Experimental study had been done to investigate the fatty acid (FA) content of the linolenic acid-amylose complexes which were prepared at different crystallization temperatures, holding time and amylase-linolenic acid ratio. The results showed the optimum conditions to make linolenic acid-amylose complexes were as followed: 80°C of crystallization temperature and 1.5h of the holding time，amylase-linolenic acid ratio of 9:1. Fatty acid composition of the complexes and physical mixtures before and after the heating destruction was detected by Gas chromatography-mass spectrometry (GC-MS). The results showed the complexes maintained higher oxidation stability than the physical mixtures.
Development on the Multi-Component Blending Yarn of Hemp/ Anti Bacteria Fine Rayon/Micro-Porous Polyester Fiber
Authors: Duan Ya Feng , Yao Jiang Wei , Zhang Yue
Published: August 2011

The hemp, anti-bacteria fine rayon and micro-porous polyester fiber were select to spin into the multi-component blending yarn by ring spinning process. The performances of these fibers were analysed, the spinning process were presented. The multi-component blending yarn of Hemp/Anti bacteria fine rayon/micro-porous polyester fiber of excellent was spun successfully, and the performance of yarn was examined and discussed.
Electronic Structures and Thermoelectric Properties of NaCo2O4 Thermoelectric Material
Authors: Ma Qiu Hua , Wang Qing Wei , Lu Peng Xian , Hou Yong Gai
Published: August 2011

The electronic structures of thermoelectric material NaCo2O4 were studied by the first-principles calculations with plane-wave pseudopotential method and generalized approximation (GGA) based on density functional theory (DFT). On the basis of calculation for electronic structures, thermoelectric properties of NaCo2O4 were also investigated in this paper. The reasons for large thermoelectric potential are large effective mass of holes at the top of valence band and 6μB net spin magnetic moment. While high electrical conductivity should be attributed to small effective mass of electrons at the bottom of conduction band, large carrier concentration near the Fermi level and narrowed energy gap. In addition, covalent bond between Co atom and O atom promotes carrier mobility and thus benefits to electrical conductivity. Na1 and Na2 have different effects on the NaCo2O4. Na1 provides local state electrons and yet Na2 provides itinerant-electrons which play important role to strongly correlated system.
Designing and Aesthetics of Daily Ceramics
Authors: Lv Jia
Published: August 2011

With the development of the living standard of the people, modern people like to be in pursuit of individualized articles for daily use, which brings more space for the development of ceramic products, and daily ceramics emerge therefore. The article respectively elaborates the substantive characteristics, aesthetics and popularity of daily ceramics.
Research on Prediction Method and Model for Maintenance Spare Parts Requirements of Armored Equipments in Wartime
Authors: Chen Shou Hua , Wei Wu , Ye Hong Bing
Published: August 2011

Nowadays we mainly take a method with proportion-coefficient basing experience to predict the carrying maintenance spare parts of armored equipments in wartime. However, the method does not accord with the expending law of maintenance spare parts in wartime. So in the paper we take support degree model and a method with phase support degree to define the rough carrying amount firstly for settling the problem. Then we take marginal utility analysis basing the restriction of transporting capability to optimizing the carrying amount of spare parts in wartime.
A Novel Vision-Based Approach for Detection of Foreign Substances
Authors: Lu Gui Liang , Zhou Yu , Yu Yao , Du Si Dan
Published: August 2011

The detection of foreign substances in injection so far is still achieved artificially, which result in low accuracy and low efficiency. This paper focuses on developing a novel vision-based approach for detection of foreign substances. Foreign substances are classified into two categories, subsiding-slowly object and subsiding-fast object. A relative movement caused by a motor helps to distinguished foreign substances from ampoule surface scratches. Moving objects in injection are divided from static ones by a background image derived from two frames. The Mean Shift Embedded Particle Filter (MSEPF) is proposed to detect moving-slowly object while Frame Distance is defined to detect moving-fast object. 200 ampoule samples filled with injection are tested. The integrated detection accuracy with this approach is 98.00%, with 97.56% accuracy for subsiding-slowly objects and 96.67% accuracy for subsiding-fast ones. The result shows that the system can detect foreign substances effectively.
Application of Improved Canny Algorithm on the IC Chip pin Inspection
Authors: Huang Ying , Pan Qi , Liu Qi , He Xin Peng , Liu Yun Feng , Yu Yong Quan
Published: August 2011

Machine vision is widely used in chip pin automation detection of defects, the accuracy of image edge extraction for detection result has very big effect. Canny edge detection algorithm is a kind of edge detection algorithm which have good comprehensive evaluation, but the Gaussian filter algorithm it used may cause image too smooth and fuzzy of the edge, and it is very sensitive for impulse noise. This paper discusses the improved methods of Canny, proposes an improved switch median filter algorithm, which is applied into Canny algorithm, makes the edge of IC Chip pin more complete and remove noise better.
A New Piezoelectric Ceramic Electronic Voltage Transducer and its Principle Design
Authors: Sang Ying Jun , Huang Xue Liang
Published: August 2011

In this paper, the piezoelectric ceramic electronic voltage transducer principles is researched, a new internal structure of the measurement system is put forward and the signal processing methods are discussed. On the basis of the analysis of freedom cantilever optical measurement methods for the longitudinal piezoelectric deformation, we proposes the piezoelectric resonance method to detect amplitude of piezoelectric ceramic and cleverly designed mechanical structure, in which the lightweight elastic material is used to support the resonance thin film. This structure overcomes the impact of cantilever longitudinal self-gravity and horizontal friction between cantilever and piezoelectric ceramic, and can improve the deformation measurement accuracy. 10kV 0.05 class transducer voltage measurement accuracy is achieved theoretically.
Purification of 1,3-Propanediol for Production of Polytrimethylene Terephthalate (PTT) from Biomass
Authors: Hong Yeon Ki
Published: August 2011

1,3-Propanediol (1,3-PDO) has received increasing attention due to usage as the monomer of biopolymer-polytrimethylene terephthalate (PTT) which can be produced from bioresources. For the economic production of 1,3-PDO, the deveolpment of cost effective removal process of by-products such as carboxylic acids from its fermentation broth. Amien-based extraction is the separation process using reactions between amine and materials extracted. The extractabilities for carboxylic acid increased with amine concentration and decreased with pH values. It was also observed that the removal efficiency of carboxylic acids from 1,3-PDO solution was above 90% without any coextraction of 1,3-PDO. From this work, it was found that the amine-based extraction can be promising separation process for the production of pure 1,3-PDO.
Preparation and Properties of the Drug-Loaded Films of Polyvinyl Alcohol-Graft-Fibroin Peptides
Authors: Wang Qun , Qi Lu
Published: August 2011

Research of biomaterials made from synthesized polymer and naturally occurring macromolecules is a promising subject. The paper reported a series of drug-loaded films manufactured by a method of solution casting, taking polyvinyl alcohol-graft-fibroin peptides (PVA-g-FP) obtained by a graft copolymerization of PVA with allyl fibroin peptides (AFP) as the polymer matrix and, the ornidazole as the model drug. The mechanical property, moisture content, dissolution degree，water absorption and water-vapor transmission rate of the films were determined respectively, and the crystalline of the films were characterized via X-ray diffraction, the morphology of the films and the dispersity profile of the drug ornidazole loaded in the matrix of PVA-g-FP were investigated via the scanning electronic microscopy (SEM). It was concluded that: with the increase of the graft efficiency of FP in the PVA-g-FP films, the mechanical property and the degree of crystalline reduced gradually; but the moisture content, dissolution degree and water-vapor transmission rate rised gradually, and especially, the dispersity of the drug loaded in the PVA-g-FP matrix improved evidently. The results may be useful in exploiting biomaterials such as artificial skin, drug delivery systems and wound dressings.
Topologically Close-Packed Phase Precipitation in Ni-Based Superalloys
Authors: Sun Fei , Zhang Jian Xin
Published: August 2011

The addition of refractory elements is effective in improving the comprehensive performance of Ni-based superalloys, and meanwhile, the precipitation trend of TCP phases increases with the elements content due to the segregation of refractory elements during high temperature service. The precipitation of TCP phases obviously decreased the creep properties and creep rupture life of superalloys. The toughness and plastic of superalloys also dramatically deteriorated. The addition of Ruthenium (Ru) is shown to suppress the formation of TCP phases in Ni-based superalloys, resulting in much improved the creep resistance and the microstructural stability. The studies on TCP phases in Ni-based superalloys including crystallography and precipitation of TCP phases and the effect of alloy composition on TCP phases are reviewed.
Research on Arch Curve of Bridge Crane Girder Based on Hyperworks
Authors: Shen Guo Min , Li Dong Bo , Yang Zhen , Li Xiang Dong
Published: August 2011

To decrease the energy loss when the crane dolly climbing and smooth its move track, the arch curves of girder were studied. Geometric model of the structure was simplified reasonably according to crane bridge structure characteristic, and the finite element models of the girder with different arch curves were established. The downwarping values of the girder with different arch curves under the rated load were obtained by simulation analysis, and further the move track of the crane dolly could be drawn. Also, the advantages and disadvantages of the arch curves were discussed. Taking maximum smoothness of the move track of the crane dolly as research object, a better arch curve was obtained by shape optimization. The research can provide a basis and reference for the arch curve design of the crane girders.
Mechanical Property of Knitted Fabric of SPF/Polyester Blended Yarn
Authors: Yang Qing Bin , Li Shou Song
Published: August 2011

In order to understand the mechanical properties with the blended ratio of soybean protein fiber/polyester blended fabric，six blended fabrics are chosen and tested. The results indicate that the strength and the bending rigidity of the blended fabric decreased，the drapability has no notability changed and the longitudinal winkle recovery decreased with the increase of the blended ratio of soybean protein fiber.
Structural Optimization of Building Materials Using Optimality Criteria Approach and its Realization in ANSYS
Authors: Zhao Ruo Hong
Published: August 2011

In this paper, the structural optimization of building materials is discussed focusing on the explicit formulation of the constraints and the optimal iteration algorithm. The whole optimization procedure was realized by programming using the APDL provided by the commercial software ANSYS. Some key points in programming are discussed such as how to determine a design variable is active or inactive during optimization iteration process. Finally an example was illustrated to demonstrate the validation of the optimization algorithm and the programming method using APDL.
Applying Computer Aided Design in Composite Molding
Authors: Wang Juan , Lai Si Yu , Liu Yi
Published: August 2011

Introduce the computer-assisted molding process system in composite components knowledge base. The feature reasoning based method is applied to the composite molding process retrieval in the light of the issues of large number of parameters, hard management and the little probability of experience sharing. Besides the production rules based reasoning approach is proposed to decide the composite materials molding technology. The overall design structure, including database of materials management, molding instance process, molding parameters management and secondary molding process selection are demonstrated. We take the object and component oriented technology to realize the design.
Study on the Kinetics of Wet Flue Gas Desulfurization by Carbide Slag
Authors: Liu Sheng Yu , Nengzi Li Chao , Lu Cheng Wei , Qiu Wei , Hu Yun Ming
Published: August 2011

Current industrial desulfurization processes involve in economic costs, if carbide slag can be used in those processes, the costs will be reduced and the goal treating waste with waste can be achieved. A mathematic reaction model was built based on the chemical reaction of desulfurization by carbide slag, the overall reaction order n=α+β=1.74, the activation energy Ea=21749.56173J/mol and the frequency factor k0=0.349533643 .
Synthesis and Luminescent Properties of Two Zn (II) Complexes with Schiff-Base Ligand
Authors: Feng Yi Min
Published: August 2011

Two Zn (II) complexes have been prepared by reaction of zinc acetate dihydrate with Schiff-base ligands. The IR spectra of complexes were measured. The luminescence properties of the Zn (II) complexes in solid and in methanol, ethanol and DMSO solution were investigated and the effects of organic solvents on the luminescent intensity of Zn (II) complexes also were studied. The results show that the Zn (II) ions formed stable complexes. The complexes exhibited maximum fluorescence emissions in blue region and the organic solvents have effect on the luminescence intensity.
Experimental Research on Effects of Coal-Fired Derived Mercury Emissions on Human Hair’s Mercury Concentrations
Authors: Wu Jiang , Fang Ji Hui , Sun Min Yu , Wu Ye Cheng , Ren Jian Xing , Pan Wei Guo , Zhang Tai , Chai Lin , Wang Jing
Published: August 2011

Cold vapor atomic adsorption spectrometry method was used in measuring mercury content in human’s hair samples after comparing the mercury measurement methods. Aqua regia-hydrofluoric acid digestion was taken to pretreat hair samples, and then mercury volume can be attained by Hydra AA Automatic mercury analyzer. Mercury concentration in about 40 percent of the tested samples exceeded the U.S. EPA recommended level 1μg/g. The results were analyzed from different respects including living environments, age distribution and dietary habits, and so on. The experimental data can supply a possible proof of mercury pollution in the studied district, and build foundation for the following full-scale mercury pollution investigation.
Construction and Expression of Database for Computer-Aided Welding Fixture Design (CAWFD) Systems
Authors: Zhang Yi , Zhou Ya Qin
Published: August 2011

Welding fixture can ensure welding dimension, improve assembly precision and efficiency. It can prevent the welding deformation. The function of welding fixture was introduced in this paper. The Classification of welding fixture component was described. Information tree and the database tables to save the unit information are designed. The unit information retrieval menu and interface based on UG, Visual C++ and database is realized.
Solder Selection of Lead-Free Reflow Soldering and Optimization of Craft Curve
Authors: Wang Wan Gang , Peng Yong
Published: August 2011

Lead-free reflow soldering craft is the most important solder craft in surface mount technology at present. However, the great reduction of crafting window brings challenges to the soldering quality and also poses higher requirement for the stability and reliability of lead-free soldering equipment. This article analyzes problems out of lead-free process, introduces the selecting principle of lead-free solder and analyzes the optimizing gist of temperature curve of lead-free reflow soldering.
Peculiarities of Formation and Annealing of VO-Related Defects in Ge Doped with Tin
Authors: Khirunenko Lyudmila I. , Pomozov Yurii V. , Sosnin Mikhail G. , Abrosimov Nikolay V. , Riemann H.
Published: August 2011

The effect of tin on the formation and temperature transformation of VO centers in Ge upon annealing has been investigated. It was found that the doping of Ge with tin leads to a change of reactions involving oxygen and vacancies and the new defect SnVO appears upon VO annealing. Doping Ge with tin gives rise to a considerable decrease in the formation efficiency of divacancies and VO centers and the latter exist in a very narrow temperatures range. VO2 complexes appear only upon annealing of SnVO centers. The assumption is made that the absorption bands situated at 718.9 and 733.6 cm-1 belong to the less stable configuration VO2* and the bands at 731.5 and 771.7 cm-1 correspond to stable configuration of VO2 centers.
Mechanisms of Dislocation Network Formation in Si(001) Hydrophilic Bonded Wafers
Authors: Vdovin Vladimir , Vyvenko Oleg , Ubyivovk Evgenii , Kononchuk Oleg
Published: August 2011

Structures of Si(001) hydrofillic bonded wafers have been studied by transmission electron microscopy. Model of three-fold nods generation during interaction of intersecting mixed and screw dislocations has been suggested and applied to analyze geometrical features of dislocation networks. Possible mechanisms of dislocation generation at the interface between Si bonded wafers are discussed.
Analysis of Auger Recombination Characteristics in High Resistivity Si and Ge
Authors: Uleckas Aurimas , Gaubas Eugenijus , Ceponis Tomas , Zilinskas Kestutis , Grigonis Rimas , Sirutkaitis Valdas , Vanhellemont Jan
Published: August 2011

The characteristics of the band-to-band Auger recombination in Czochralski-grown high resistivity Si and Ge single crystals have been studied using a contactless technique to measure excess carrier decay transients based on infrared absorption by free carriers. The measurements are performed using laser light excitation with wavelengths ranging from 1.2 to 2.5 µm to reduce inhomogeneity effects in the extraction of the Auger recombination parameters. A linear approximation of the initial excess carrier decay lifetime yields an approximate value of the Auger recombination coefficient in Ge γA,Ge ≈ 2×10-31 cm6/s, which is close to that in Si. These characteristics also indicate that the difference in Auger recombination coefficients for the ehh and eeh processes is small. A more detailed fitting procedure applied simultaneously on a series of experimental transients yields a more accurate value of (8±3)×10-31 cm6/s for the Auger recombination coefficient in Ge.
Characterization of Structural Defects in Germanium Epitaxially Grown on Nano-Structured Silicon
Authors: Zaumseil Peter , Yamamoto Yuji , Bauer Joachim , Schubert Markus Andreas , Matejova Jana , Kozlowski Grzegorz , Schroeder Thomas , Tillack Bernd
Published: August 2011

Selective epitaxial growth of germanium (Ge) on nano-structured Si(001) wafers is studied to evaluate the applicability of the nano-heteroepitaxy (NHE) approach on Ge-Si system. Based on a gate spacer technology established in advanced silicon microelectronics periodic arrays of nano-scaled Si islands are prepared, where Ge is deposited on top by reduced pressure CVD. The spacing of these structures is 360 nm. The structural perfection of the deposited Ge is investigated by transmission electron microscopy and X-ray diffraction. It is found that SiO2used as masking material is responsible for the suppression of the desired strain partitioning effect according to NHE. Even for 10 nm oxide thickness, the lattice of Ge layers deposited on Si nano-islands relaxes completely by generation of misfit dislocations at the interface. The occurrence of additional structural defects like stacking faults and micro twins can be controlled by suited growth conditions.
C-V - and DLTS-Investigations of Pyramid-Shaped Ge Quantum Dots Embedded in N-Type Silicon
Authors: Rangel-Kuoppa Victor Tapio , Tonkikh Alexander , Zakharov Nikolay , Werner Peter , Jantsch Wolfgang
Published: August 2011

We investigate self-assembled pyramid-shaped Ge Quantum Dots (QDs) with lateral dimensions of 15 nm, and heights of 2.5-3 nm. These Ge QDs were grown by Molecular Beam Epitaxy (MBE) on n-type Si(100) substrates using the Sb-mediated growth mode. The resistivity of the substrates was about 5 Ωcm. The Si buffer layer below the QDs and the Si capping layer above them were doped up to 1018cm-3by Sb. Cross-section transmission electron microscopy shows the QDs and the Sb delta-doped layers. Using standard photolithographic techniques, a 0.3 mm2Au Schottky contact was applied to the epilayer, while an Ohmic contact was formed on the back side of the substrate. Plotting C-2vs. V plot reveals the nominal doping of 1018cm-3. DLTS studies revealed two levels with fitted activation energies of 49 meV and 360-390 meV. They are related to the Sb doping and the Pb interface states, respectively. The simulation suggests a deep level with a volumetric concentration of 2.55×1015cm-3. Multiplying this value by the thickness of the depletion region obtained from the CV measurements, we find that the deep level capture about 5.8×109electrons per cm2.
Suppressor of Cytokine Signaling 2 Is a Feedback Inhibitor of TLR-Induced Activation in Human Monocyte-Derived Dendritic Cells
Authors: Posselt Gernot , Schwarz Harald , Duschl Albert , Horejs-Hoeck Jutta
Published: August 2011

Dendritic cells (DCs) are key players in initiating and directing the immune response. Therefore, their activation state and functional differentiation need to be tightly controlled. The activating stimuli and their signaling networks have long been an area of focus in DC research. Recent investigations have also shed light on the mechanisms of counterregulation and fine-tuning of DC functions. One class of proteins involved in these processes is the family of suppressors of cytokine signaling (SOCS), whose members were originally described as feedback inhibitors of cytokine-induced JAK/STAT signaling. Essential roles in DC function have been assigned to SOCS1 and SOCS3. In this article, we show that SOCS2 also is involved in DC regulation. In human and in murine DCs, SOCS2 is a highly TLR-responsive gene, which is expressed in a time-delayed fashion beginning 8 h after TLR ligation. Functionally, silencing of SOCS2 in DCs results in hyperphosphorylation of STAT3 at later time points. As a consequence, SOCS2-deficient DCs secrete increased amounts of the cytokines IL-1β and IL-10, both being transcriptional targets of STAT3. We propose a model in which SOCS2 acts as a negative regulator of TLR-induced DC activation. The delayed expression of SOCS2 provides a mechanism of late-phase counterregulation and limitation of inflammation-driving DC activity.
Differential Regulation of Proximal and Distal Vβ Segments Upstream of a Functional VDJβ1 Rearrangement upon β-Selection
Authors: Brady Brenna L. , Bassing Craig H.
Published: August 2011

Developmental stage-specific regulation of transcriptional accessibility helps control V(D)J recombination. Vβ segments on unrearranged TCRβ alleles are accessible in CD4−/CD8− (double-negative [DN]) thymocytes, when they recombine, and inaccessible in CD4+/CD8+ (double-positive [DP]) thymocytes, when they do not rearrange. Downregulation of Vβ accessibility on unrearranged alleles is linked with Lat-dependent β-selection signals that inhibit Vβ rearrangement, stimulate Ccnd3-driven proliferation, and promote DN-to-DP differentiation. Transcription and recombination of Vβs on VDJβ-rearranged alleles in DN cells has not been studied; Vβs upstream of functional VDJβ rearrangements have been found to remain accessible, yet not recombine, in DP cells. To elucidate contributions of β-selection signals in regulating Vβ transcription and recombination on VDJβ-rearranged alleles, we analyzed wild-type, Ccnd3−/−, and Lat−/− mice containing a preassembled functional Vβ1DJCβ1 (Vβ1NT) gene. Vβ10 segments located just upstream of this VDJCβ1 gene were the predominant germline Vβs that rearranged in Vβ1NT/NT and Vβ1NT/NTCcnd3−/− thymocytes, whereas Vβ4 and Vβ16 segments located further upstream rearranged at similar levels as Vβ10 in Vβ1NT/NTLat−/− DN cells. We previously showed that Vβ4 and Vβ16, but not Vβ10, are transcribed on Vβ1NT alleles in DP thymocytes; we now demonstrate that Vβ4, Vβ16, and Vβ10 are transcribed at similar levels in Vβ1NT/NTLat−/− DN cells. These observations indicate that suppression of Vβ rearrangements is not dependent on Ccnd3-driven proliferation, and DN residence can influence the repertoire of Vβs that recombine on alleles containing an assembled VDJCβ1 gene. Our findings also reveal that β-selection can differentially silence rearrangement of germline Vβ segments located proximal and distal to functional VDJβ genes.
EBI2 Guides Serial Movements of Activated B Cells and Ligand Activity Is Detectable in Lymphoid and Nonlymphoid Tissues
Authors: Kelly Lisa M. , Pereira João P. , Yi Tangsheng , Xu Ying , Cyster Jason G.
Published: August 2011

EBV-induced gene 2 (EBI2) was recently shown to direct the delayed movement of activated B cells to interfollicular and outer follicular regions of secondary lymphoid organs and to be required for mounting a normal T-dependent Ab response. In this study, we show that EBI2 promotes an early wave of Ag-activated B cell migration to the outer follicle in mice. Later, when B cells have moved to the T zone in a CCR7-dependent manner, EBI2 helps distribute the cells along the B zone–T zone boundary. Subsequent EBI2-dependent movement to the outer follicle coincides with CCR7 downregulation and is promoted by CD40 engagement. Using a bioassay, we identify a proteinase K-resistant, hydrophobic EBI2 ligand activity in lymphoid and nonlymphoid tissues. Production of EBI2 ligand activity by a cell line is sensitive to statins, suggesting production in a 3-hydroxy-3-methyl-glutaryl-CoA reductase–dependent manner. CD40-activated B cells show sustained EBI2-dependent responsiveness to the bioactivity. These findings establish a role for EBI2 in helping control B cell position at multiple stages during the Ab response and they suggest that EBI2 responds to a broadly distributed lipid ligand.
Novel Highly Sensitive IL-10–β-Lactamase Reporter Mouse Reveals Cells of the Innate Immune System as a Substantial Source of IL-10 In Vivo
Authors: Bouabe Hicham , Liu Yunying , Moser Markus , Bösl Michael R. , Heesemann Jürgen
Published: August 2011

In this study, we report on a novel, highly sensitive IL-10 reporter mouse based on the reporter enzyme β-lactamase and the fluorescence resonance energy transfer substrate coumarin-cephalosporin-fluorescein (4). In contrast to an IL-10 reporter mouse model that we generated by using enhanced GFP as reporter and allowed tracking IL-10 expression only in T cells, the IL-10–β-lactamase reporter (ITIB) mouse enables us to easily analyze and quantify IL-10 production at the single-cell level in all myeloid and lymphoid cell types. Furthermore, the ITIB mouse allows studying of the kinetics of IL-10 expression on a single-cell basis and provides a valuable tool for in vivo screening of cell type-specific IL-10–modulating drugs. Remarkably, the ITIB mouse revealed that, although a significant portion of each myeloid and lymphoid cell type produces IL-10, macrophages represent the major IL-10 producer population in several organs of naive mice. Moreover, using the examples of bacterial infection and transplantable skin melanoma models, we demonstrate the exceptional applicability of the ITIB mouse for the identification of IL-10–producing cells during immune responses in vivo. In this study, we identified tumor-infiltrating F4/80+ macrophages as the major source for IL-10 in B16-F10 melanoma in vivo. During systemic infection with Yersinia enterocolitica, although the proportion of IL-10+ cells increased in each myeloid and lymphoid cell type population, infiltrating CD11b+Ly6G+ neutrophils represent a majority among IL-10–producing cells at the site of infection. We conclude that cells of the innate immune system that are involved in immune homeostasis or immune responses are substantial sources of IL-10.
Characterization of Certain Bacterial Strains for Potential Use as Starter or Probiotic Cultures in Dairy Products
Authors: MONTEAGUDO-MERA A. , CARO I. , RODRÍGUEZ-APARICIO L. B. , RÚA J. , FERRERO M. A. , GARCÍA-ARMESTO M. R.
Published: August 2011

The present work was aimed at characterizing 12 strains of lactic acid bacteria (LAB) to obtain improved potential starter or probiotic cultures that could be used for making dairy products from ewe's milk and cow's milk. Eight strains with antimicrobial properties, isolated from ewe's milk and from cheese made from ewe's and/or cow's milk, were studied. They were identified as Enterococcus faecalis (five strains), Lactococcus lactis subsp. cremoris, Leuconostoc mesenteroides, and Lactobacillus paracasei subsp. paracasei (one strain of each species). Additionally, four strains were obtained from the American Type Culture Collection: Lactobacillus casei 393 (isolated from cheese), L. lactis subsp. lactis 11454 (origin nonspecified and a producer of nisin), and two strains isolated from human feces (L. paracasei subsp. paracasei 27092 and Lactobacillus rhamnosus 53103, antibacterial agent producer). All E. faecalis strains showed at least one virulence factor (either hemolysin or gelatinase), which emphasizes the importance of these studies in this species. Both L. lactis strains and most Lactobacillus spp. were good acidifiers in ewe's milk and cow's milk at 30°C. High β-galactosidase activity, as well as aminopeptidase activities that favor the development of desirable flavors in cheese, were detected in all Lactobacillus spp. strains. Furthermore, L. rhamnosus ATCC 53103 showed α-fucosidase activity (thought to help colonization of the intestine) and lack of α-glucosidase activity (a trait considered positive for diabetic and obese humans). This last enzymatic activity was also lacking in L. lactis ATCC 11454. L. mesenteroides was the only strain D(−)-lactic acid producer. The selection of any particular strain for probiotic or dairy cultures should be performed according to the technological and/or functional abilities needed.
Abiotic and Biotic Factors Affect Efficacy of Chlorfenapyr for Control of Stored-Product Insect Pests
Authors: KAVALLIERATOS NICKOLAS G. , ATHANASSIOU CHRISTOS G. , HATZIKONSTANTINOU ANN N. , KAVALLIERATOU HELEN N.
Published: August 2011

Laboratory bioassays were conducted to assess pyrole chlorfenapyr as a potential grain protectant against adults of Rhyzopertha dominica, Sitophilus oryzae, Prostephanus truncatus, Tribolium confusum, and Liposcelis bostrychophila. Factors such as dose (0.01, 0.1, 0.5, 1, 5, and 10 ppm), exposure interval (7 and 14 days), temperature (20, 25, and 30°C), relative humidity (RH; 55 and 75%), and commodity (wheat, maize, barley, and paddy rice) were evaluated. Progeny production was assessed after 74 days of exposure. For L. bostrychophila and T. confusum the increase of dose increased mortality. After 7 or 14 days of exposure, mortality was low at doses of ≤1 ppm and did not exceed 23 or 36%, respectively, for L. bostrychophila or 13 or 58%, respectively, for T. confusum. After 14 days of exposure, mortality of S. oryzae at 30°C and 75% RH was 82.2%. Mortality of P. truncatus was considerably higher than that of the other species. At 0.5 ppm, mortality exceeded 81% after 7 days of exposure and 91% after 14 days of exposure. Progeny production of L. bostrychophila was extremely high. Very few progeny were found for T. confusum. For S. oryzae, offspring emergence was high, except at 20°C and 55% RH. For P. truncatus, progeny production in the treated maize was not avoided, even at 10 ppm. In the case of S. oryzae, at 0.1 ppm and after 14 days of exposure, mortality in wheat was higher than in the other three commodities. For R. dominica, mortality was low at 0.1 and 1 ppm for paddy rice but reached 74.4% in barley after 14 days of exposure. For T. confusum, mortality was low at 0.1 and 1 ppm in all commodities. For progeny production counts, for S. oryzae or R. dominica, adult emergence was higher in paddy rice than in the other three commodities. Finally, overall T. confusum progeny was low. Chlorfenapyr efficacy varied remarkably among the combinations tested, and it may be a viable grain protectant in combination with other insecticides.
Occurrence of Vibrio spp. in Fish and Shellfish Collected from the Swiss Market
Authors: SCHÄRER K. , SAVIOZ S. , CERNELA N. , SAEGESSER G. , STEPHAN R.
Published: August 2011

The genus Vibrio includes gram-negative bacteria that inhabit estuarine ecosystems. V. cholerae, V. parahaemolyticus, and V. vulnificus pose a considerable public health threat as agents of sporadic and epidemic foodborne infections associated with the consumption of raw or undercooked contaminated fish or shellfish. In this study, we analyzed 138 fish and shellfish samples collected from the Swiss market (fish fillets [n = 102], bivalves [n = 34], and squid [n = 2]). Microbiological analysis was done according to International Organization for Standardization method 21872-1/21872-2:2007, using thiosulfate citrate bile sucrose agar and chromID Vibrio agar as selective agar. Presumptive-positive colonies on thiosulfate citrate bile sucrose agar or chromID Vibrio agar were picked and were identified by the API 20E and species-specific PCR systems. V. cholerae isolates were tested further by PCR for the presence of the cholera toxin A subunit gene (ctxA). V. parahaemolyticus isolates were tested by PCR for genes encoding for thermostable direct hemolysin (tdh) and TDH-related hemolysin (trh). V. cholerae was isolated from three samples and V. parahaemolyticus from eight samples. None of these strains harbored species-specific virulence factors. Further, V. alginolyticus was isolated from 40 samples, and V. fluvialis was isolated from 1 sample. Our study provides, for the first time, data for the assessment of exposure to Vibrio spp. in raw fish and bivalves consumed in Switzerland.
Natural Occurrence of Fumonisins B1 and B2 in Corn from Three Main Production Provinces in China
Authors: FENG Y. Z. , LU X. H. , TAO B. , PANG M. H. , LIU Y. C. , DONG J. G.
Published: August 2011

A total of 255 corn samples collected in 2010 from three main corn production provinces of China (Liaoning, Shandong, and Henan) were analyzed for contamination with fumonisins (FB1 and FB2). The incidence of contamination was significantly higher in samples from Liaoning than in samples from the other two provinces. Approximately 80.0% of the samples from Liaoning were contaminated with fumonisins, with a mean total fumonisin concentration of 3,990 ng/g. In contrast, the mean total fumonisin concentrations were 845 and 665 ng/g in samples from Shandong and Henan, respectively. The probable daily intake of fumonisins (0.3 μg/kg of body weight) is within the provisional maximum tolerable daily intake of 2.0 μg/kg of body weight set by the Joint Food and Agriculture Organization and World Health Organization Expert Committee on Food Additives.
The influence of mindfulness-based stress reduction and walking on the psychological well-being of female informal caregivers: A pilot study
Authors: Van Puymbroeck, PhD, CTRS Marieke , Hsieh, MS Pei-Chun
Published: August 2011

Informal caregivers, who provide unpaid care for family or friends, often experience numerous threats to their psychological well-being as a result of providing care. This study compared a traditional physical activity (mall walking, MW) to an alternative therapeutic intervention (mindfulness-based stress reduction, MBSR) to examine the impact on the psychological well-being of informal caregivers. While both groups experienced a decrease in psychological well-being, caregivers in the MBSR group experienced fewer exacerbations in depressive symptoms and subjective burden when compared with caregivers in the MW group. It is possible that mindfulness techniques may provide some protection against the exacerbation of negative effects on caregivers’ psychological wellbeing. The use of MBSR as a therapeutic intervention in therapeutic recreation practice may be warranted, but requires further study.