bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study on the Dynamic Performance of Long-Span Steel Arch Bridge in Passenger Dedicated Line
Authors: Wei Xian Feng , Bu Jian Qing , Chen Jian Guo
Published: March 2012

By the experiment on dynamic performance of long-span steel arch bridge, the natural frequency and dynamic responses of the 140m steel box-section tied arch bridge over the Ting Si River Bridge in the Wuhan-Guangzhou Passenger Dedicated Line are tested. the tested results of the bridge dynamic responses show that the bridge structure can meet the security requirements when CRH2 EMU runs on it in the speed of 250 to 350km/h.the lateral and vertical stiffness are larger, the vertical and lateral natural frequencies and the other dynamic performances of the bridge can meet the requirements of the relevant norms, When the CRH2 EMU runs across the steel box-section arch bridge in different speeds
Structural Damage Detection of Continuous Beam by NExT Based Wavelet Packet Energy
Authors: Yan Peng , Li Qiao
Published: March 2012

For the purpose of effective damage localization, combined with natural excitation technique (NExT) and wavelet packet (WP) decomposition method, a new algorithm named NExT based wavelet packet energy (WPE) damage detection algorithm was proposed for continuous beam. Finite measuring points of bridge structure response are set firstly, and then classified as reference points and response points. Calculated with each corresponding two-point, the virtual impulse response signals are taken as input data of WP decomposition method. Finally, structural damage detection is carried out by using WPE as damage index. Through a three-span continuous beam finite element model, this algorithm was discussed with respect to the applicability and effectiveness of damage detection. The analysis results reveal that, with certain robustness to noise, the proposed algorithm has favorable effect on damage interval localization. Therefore, the algorithm put forward is practical to detect damage of continuous beam.
Safety Recognition Model of Urban Railway Level-Crossings Based on Attribute Mathematics Method
Authors: Wang Hong De , Deng Han
Published: March 2012

Focusing on the road-railway level-crossings of the urban, basing on the attribute mathematics methods, the access safety influence factors of the railway level-crossings are analyzed. Basing on the analytic hierarchy process method, the assessment indexes, which impair the level-crossings system safety status, are set. Firstly, the attribute measurements of every single-index are calculated by mean of the construction of attribute measurement functions. Secondly, according to the similarity function theory, the similarity weights of the influence factors are defined, so as to assess the multi-indexes measurements objectively. Finally, make use of the confidence criterion to recognize the level-crossing system safety. Taking one of the railway level-crossings in Dalian as an example, the assessment results show that the attribute recognition result would not be affected by the index weight, namely, the weight values of the assessing indexes are considered as the same. The study shows that the method is feasible, reliable and easy for the synthetic safety assessment of the urban railway level-crossings safety
The Method of Automatic Counting of Circular Objects Based on the Matching Method of Fuzzy Circular Template
Authors: Li Qiang , Li Guan Nan
Published: March 2012

Importing ideas of Geometry and Fuzzy into traditional matching method of template, generates the matching method of fuzzy circular template. The template of this method is data of a circle with fixed radius and width of line by fuzzy function, its matching is judging the extent of similarity of the object of matching bitmap and fuzzy circular of template. This method utilizes efficiently the shape of matching object and overcome disadvantageous influence of the factors of bitmap noise and unequal size and irregular shape of matching object.
Fracture Reasons and Improvements for the Running Gear of Shearers
Authors: Song Chun Yu , Liu Jing Ru , Zhang Xiu Juan
Published: March 2012

Running traction mechanism of shearers is adopted as the analysis object in this paper. The finite element models for the elastic contact analysis between the running gears and pin-rails are created. When the gears are running, the variation principles of contact spots, contact force, and internal stress for the gears and pin-rails at the different contact positions are analyzed. The calculation results show that the maximum stress is located at the edges of the gear teeth for the different contact positions. When the teeth are loaded with the repeated large stress, cracks are produced at the tooth edges at first and then are growing. The tooth breakage is produced at last. Gear chamfers using two circulars at the tooth edges can change the location of the maximum stress and the maximum MISES stress can be reduced by 20% or more. Therefore, the fracture problem of gear teeth is solved basically.
Development of Special Automatic Welding Machine for Adaptor Flange of Tubular Parts and Cylindrical Parts
Authors: Song Jin Hu
Published: March 2012

In general, flange is fixedly connected with tubular parts or cylindrical parts through manual welding. For high labor intensity, low efficiency and poor welding quality of manual welding, a special automatic welding machine for adaptor flange of tubular parts or cylindrical parts is developed. It mainly consists of machine frame, rotary worktable, swing arm, sliding shelf, wire feeder, drive unit, control cabinet and welding torch. The welding machine has two rotary worktables controlled by PLC. With the advantages of simple structure, low production cost, high welding speed, good welding quality and low labor intensity, it is particularly suitable for small and medium sized enterprises
Controllable Synthesis of CaMoO4 Microcrystals with Tailored Morphologies and Optical Properties
Authors: Lv Li , Xie Yu Zhe , Liu Xiao Qing , Su Yi Guo , Wang Xiao Jing
Published: March 2012

CaMoO4 microcrystals with controllable morphologies and luminescent properties were successfully synthesized via hydrothermal treatment. The as-prepared samples are characterized using X-ray powder diffraction, scanning electron microscopy; Fourier transformed infrared spectra. By adjusting the fundamental experimental parameters including reaction time, temperature and the amount of organic additives, CaMoO4 exhibited various morphologies, such as particles, dumbbells as well as flowers. Moreover, it is seen that CaMoO4 can be well crystallized with tetragonal structure at room temperature. The photoluminescence spectra of CaMoO4 display a strong and broad band emission with a maximum at 550 nm under excitation wavelength of 310 nm at room temperature. The luminescent intensity of CaMoO4 varied with the reaction time and temperature and was optimized at 200 oC, 45 h. The work provides a facile synthetic route for the construction of inorganic materials with controllable morphologies and luminescent properties
Efficient Synthesis and Photochromic Properties of a New Unsymmetrical Photochromic Diarylethene Base on Naphthalene Unit
Authors: Wang Ren Jie , Pu Shou Zhi , Cui Shi Qiang
Published: March 2012

A new diarylethenes [1-(2-methyl-1-naphthyl), 2-(2-methyl-5-1,3-dithiolane-3-thienyl)]perfluorocyclopentene 1o based on a hybrid structure of naphthalene and thiophene has been developed. Its properties including photochromism, kinetics and fluorescence were investigated in detail. The results indicated that the compound exhibited good photochromism, which changing from colorless to orange after irradiation with 297 nm UV light both in solution and in PMMA film. The fluorescence switching properties shown the fluorescence spectrum of diarylethene 1o was decreased remarkable along with the cyclization reactions. Finally, using this diarylethene as recording medium, polarization optical recording was carried out successfully.
Ionic Liquid Assisted Sol-Gel Prepared Ce-Doped ZnO
Authors: Jiang Yan Li , Liu Yan , Yang Li Juan , Liu Jia Yao , Lin Yu Fei
Published: March 2012

Ce4+-doped zinc oxide was prepared by Ionic liquid assisted sol - gel method using oxalic acid and zinc acetate as starting material for the first time. And rhodamine B as the target material to study ionic liquid assisted preparation of Ce4+-doped ZnO photocatalytic performance. ZnO was determined by SEM and XRD for introduction of ionic liquids and Ce4+ derived from nano-ZnO surface morphology and crystal before and after. The results show that the Ce4+-doped nano-ZnO crystal structure of a rod. In ionic liquids based on the Ce4+-doped photocatalytic properties of ZnO better. The degradation of rhodamine B 30min when the degradation rate of 90%.
Intelligent Materials and Contemporary Industrial Design
Authors: She Xing , Wang Hai Bo , Zhuang De Hong
Published: March 2012

The intellectualization of material defined the direction of material science development. This paper illustrates the purpose of researching intelligent materials and how to apply intelligent materials in the industrial design. Moreover, this paper also gives expectations of using intelligent material for future products
New Technics of Restoring High-Strength Steel Parts on Airplane by Brush Plating a Composite Coating of Diamond
Authors: Ge Wen Jun , Lv Qin Yun , Xia Cheng Bao
Published: March 2012

In order to solve the restoring problem of the high-strength steel accessories on the airplane, the feasibility study about restoring the high-strength steel accessories by electro-brush plating has been done. The restoring technics was discussed, furthermore, we test the rigidity, binding force and abrasion resistance of the parts after restoring. It indicates that the restoring technology owns many advantages, such as simple technology flow, convenient operation, low cost, strong binding force between the coating and substrate and good abrasion resistance, which could meet the request of the use completely. So it is worth extending.
Preparation and Characterization of Glass Flake/Nano-TiO2 Compound Particle on Low Temperature
Authors: Guo Yi , Yan Jun , Du Shi Guo , Wang Bin , Liu Jia
Published: March 2012

Glass flake has excellent capacity of anti-infiltration, for perfecting the bonding of resin and glass flake, Using butyl titanate as the main material, the glass flake/TiO2 composite particle doped by Sn4+ at low temperature was prepared. SEM observation indicated that TiO2 particles covered the glass flake powder surface and form nanometer/micron structure. XRD showed TiO2 particle was amorphous, the particle size was very small or just formed halfcrystal. Acidity effected the growth speed of crystal and structure of growth elementary. SnCl4 could form heterogeneous crystal to lead the TiO2 film formation.
Research on Process of Copper-Infiltration on 304 Stainless Steel by Double Glow Plasma Technology
Authors: Wang Yan , Xu Jin Yong , Gao Cheng , Gao Bo
Published: March 2012

The effect on diffusion layer depth and copper content of the variation of various parameters in copper-infiltrated process on stainless steel surface by double glow plasma technology were researched. The process parameters contain Ar2 pressure, source voltage, heat insulation temperature and heat insulation time. The best process parameters are as follows: gas pressure:20Pa, source voltage:1000V, heat insulation temperature:950°C and heat insulation time:3h. Nowadays, the main methods of copper-infiltrated on stainless steel surface include: solid-infiltration method, paste-infiltration method, particle beam injection etc[1~4]. The strength of diffusion layer treated by the plasma metal infiltration technique is comparable to metallurgical bonding strength, and the process is low cost and less pollution.The paper systematically studied the plasma copper-infiltrated process on 304 Stainless Steel. The initial copper-infiltrated process parameters on 304 Stainless Steel were as follows[5]: Ar2 pressure: 20 Pa; source voltage: 1000 V; heat insulation temperature: 950°C; heat insulation time: 3 hours. The optimum seeking method is based on the initial process parameters, varying the value of one parameter each time. Four values of one parameter is a group contrasting experiments. Testing diffusion layer depth and copper content on surface of each experiment to be standerds of evaluation every value. The values of each parameter to be seleted were as follows: Ar2+ pressure: 10 Pa, 15 Pa, 20 Pa, 25 Pa; source voltage: 800V, 900V, 1000V, 1100V; heat insulation temperature: 800°C, 900°C, 950°C, 1000°C; heat insulation time: 2.5 h, 3 h, 3.5 h, 4 h.
Researches of a Magneto-Rheological Fluid Damper with External Coil Based on Electromagnetic Finite Element Analysis
Authors: Xu Xiao Mei , Zeng Cai Min
Published: March 2012

In vibration control field magneto-rheological (MR) fluid dampers are semi-active control devices that have recently begun to receive more attention. This paper presents a new type of MR fluid damper with external coil. The new structure of the damper was optimized and analyzed based on a static magnetic analysis with the help of electromagnetic finite element analysis (FEA) using the software of ANSYS. The damping characteristics of the damper were theoretically researched. Research results show that the designed MR fluid damper with external coil has wider scope of damping adjustment and strong energy-dissipating ability. The study method in this paper and the obtained results will help designers to create more efficient and reliable MR fluid dampers.
Synthesis and Characterization of Modified Epoxy-Silicone Resin
Authors: Chen Qing Chang , Ma Lan Zhi , Chu Qing Guo , Zhang Ming , Wu Hang
Published: March 2012

Chosed silicone resin with better waterproof and weatherability as raw material, epoxy resin and polyester as modifiers, developed a modified adhesive resin. By researching of the relation between content and property, the matching curing agent with polyfunctional groups was prepared, the modified resin was completely solidified. Properties test and analysis demonstated that the cured modified resin provided super resistance of salt fog and better surface abrasion resistance and perfectible high-temperature resistance
The Effect of Microstructure on Mechanical Properties and Fatigue Crack Growth Behavior of TC4-DT Alloy
Authors: Zhu Li Wei , Zhu Zhi Shou , Wang Xin Nan , Cao Chun Xiao
Published: March 2012

This paper examines the influence of different microstructure on the mechanical properties and fatigue crack growth behavior of TC4-DT alloy at room temperature. Different heat treatments were carried out in order to produce the microstructure of bimodal and lamellar conditions. Results show that, the tensile properties and fracture toughness of bimodal and lamellar microstructure was varied by different heat-treatment. In contrast on bimodal microstructure, the lamellar microstructure presents high fracture toughness and low fatigue crack growth rate, but the yield stress and ductility declines. The analysis results indicted that the lamellar microstructure obtained by air cooling from the  phase field showed the integrated condition of tensile properties and fracture toughness duo to the fine secondary  lamella, and the better fatigue crack growth behavior.
Genetic Algorithm Application in Cutting Way
Authors: Liu Chun Hua , Xiao Ji Xian , Wang Xin Chun , Gao Yue Qin
Published: March 2012

Cutting way is very common in the usual production, the method of solving is a hotspot. Here, we use genetic algorithm and create an innovative coding way to solve this question. It is very easy to operate, grasp furthermore also improve the calculate speed and solution quality.
The Preparation of Platinum Nanoparticles on Titanium Using Chemical Reductive Growth Procedures
Authors: Guo Li , Hu Jian Qiang , Zhang Hu , Yang Shi Zhao
Published: March 2012

The synthesis of platinum nanoparticles by reduction of H2PtCl6 with ascorbic acid has been studied. By high-resolution electron microscope and XRD analyses, the resultant nanoparticles have been found to be pure platinum of fcc structure. Their sizes were observed to increase with the increases chemical reductive with 24h. Then, platinum nanoparticles directly attached to Ti plates(Pt nanoparticles/Ti) were successfully fabricated. In this method, platinum nanoparticles could be grown on the Ti surface via the one-step immersion into the growth solution containing PtCl62- and ascorbic acid. The attached and grown platinum nanoparticles were spherical having an agglomerated nanostructure composed of small nanoclusters. The present Pt nanoparticles/Ti may be promising for a new type of electrode material.
Use of Versatile Binaphthalene Derivative in Chromatic-Stability Non-Doped White Organic Light Emitting Diodes
Authors: Wang Fei Fei , Lv Yan Fang , Zhou Peng Chao , Lin Hong , Wei Na , Wei Bin
Published: March 2012

We have investigated the properties of the ultra-thin layer all-fluorescent nondoped white organic light emitting diodes based on blue-emitting binaphthalene derivative (BN) and ultra-thin green and red emitters. By optimizing the thickness of BN, we found that the device exhibited a high color rendering index (CRI) of 84 and high chromatic-stability with the Commission International de L’Eclairage coordinates shifting from (0.26, 0.32) to (0.27, 0.33) as the luminance increased from 40 to 10645 cd/m2. In addition, we also achieved a low current efficiency roll-off, which current efficiency only reduced from 3.77 cd/A to 3.36 cd/A when the current density increased from 13 mA/cm2 to 104 mA/cm2. High CRI and low efficiency roll-off are of significance for the applications of organic light-emitting diodes in display and lighting.
Precast Concrete Pipe Pile Perfusion Control System Design
Authors: Ren Cai Xia
Published: March 2012

The paper introduces the work process and control requirements of precast concrete pipe pile perfusion. Th design is based on the S7-200PLC and AE80THTD touch screen control system. It elaborates the hardware components of control system, I / O configuration, software workflow and control chart. The practical operation shows that the control system is convenient to manufacture, install and commission, easy to operate, and it is stable and reliable.
Design and Realization of π／4-DQPSK Modulation Circuit Based on FPGA
Authors: Zhu Hong Li , Sun Xia
Published: March 2012

Technology of digital modulation plays an important role in digital communication system, the combination of digital communication technology and FPGA is a certain trend. This paper designs and realizes a new π／4-DQPSK modulator based on FPGA. The simulation result provides the correction of the design. With simple solution, high integration and high reliability, this π／4-DQPSK modulator can be widely used in digital communication field.
Management System of Parallel Lithium Batteries Based on MCU
Authors: Mao Jing Kui , Zheng Shu
Published: March 2012

Now，it is a waste of large capacity cell in series and will cause fatal damage to the whole battery if one cell occurs failure. In this paper, a scheme of Parallel lithium/polymer battery Charge-Discharge intelligent management system with MCU(Micro-Computer Unit) and switch power supply technology is introduced. Under DC-DC transform of switch power, it can boost voltage of battery from 4.2V to voltage needed, but also reduce power waste of battery charge system and requirement of cell in coherence.
MWGANN Prediction Model for Electromechanical Equipment Running State
Authors: Xu Xiao Li , Jiang Zhang Lei , Chen Peng
Published: March 2012

To ensure the rotary electromechanical equipment injection pump unit safe and stable operation, status assessment parameters should be predicted used by appropriate prediction model. This paper presents a genetic algorithm optimization neural network prediction model based on mean function new information-weighted theory (MWGANN prediction model). MWGANN prediction model can optimize the neural network structure parameters and improve the prediction accuracy and prediction timeliness by using the recency difference of time series data. Collecting large rotating injection pump unit vibration intensity time series in the industrial site, MWGANN prediction model and GANN prediction model are applied to predict trend. The results show that MWGANN model achieved good results in prediction accuracy and prediction timeliness.
Research on Regulating of Engine Cooling Intensity with Fuzzy Control
Authors: Luo Qing Guo , Ran Guang Zheng , Gong Zheng Bo
Published: March 2012

In order to improve the overall performance of the engine cooling system, make the engine work in a stable and suitable thermal condition, a fuzzy controller for the engine cooling system was designed, then the cooling control model was established in Simulink, and the engine cooling system model of a diesel engine was built in GT-cool. Simulation computation was taken on the coupling of the two models. The results indicate that fuzzy control has visible effect for the improvement of the cooling system.
Signal Extraction Based on an Improved EMD Method
Authors: Chen Yan Long , Zhang Pei Lin
Published: March 2012

The main purpose of this paper is to propose an improved empirical mode decomposition (EMD) approach based on principal component analysis (PCA). EMD is a time-frequency analytical method used to deal with non-linear and non-stable signals. But it generally fails to separate IMFs from primordial signal consisting of several adjacent frequencies,especially when noise is strong.In this papar the PCA is introduced to solve this problem.First,PCA is used to pro-process sample signal to get principal components. Then several signals are reconstructed by principal components.Reconstructing signals can separate adjacent frequencies and depress noise.With the EMD method again,right characteristic information is obtained from intrinsic mode functions (IMFs). Simulated signal is analyzed by the proposed method, as shown by example. Compared to the EMD method, this improved method is proved to be superior to the traditional EMD method in extracting the characteristics of signal,which consisting adjacent frequencies and interfered by strong noise.
The Building of Cigarette Factory Warehousing Management System Based on Data Warehouse
Authors: Dong Xiang Ying , Wang Xue Qun
Published: March 2012

The construction of X Cigarette Factory’s Material Order and Warehousing Management System is underway, at the same time, the new system and the office automation system, the production execution system and the automated logistics system can form an integral enterprise business that operates on the basis of supply chain. It is necessary to be point out that it is an approach with Chinese characteristics on developing information system: compared with integrative and Process Reengineering construction model of the developed countries, most Chinese enterprises like X Cigarette Factory tend to develop information system gradually and by outsourcing partly subject to financial, staff and process stability factors. X Cigarette Factory’s practices and experiences can gave an inspiration to other small and medium enterprises in China.
The Control Technology of Air-Conditioning Based RBF Adaptive Neural Network
Authors: Li Jie Jia , Chen Hao , Liu Dai Yan
Published: March 2012

The central air-conditioning control system is a nonlinear, large inertia, delay system, controller the performance, relates directly to the control effect, energy loss and comfort level. This paper analyzes the working principle and characteristics of the air-conditioning system, and needle air-conditioning control deficiencies, with a prediction neural network control technology, established the neural network predictive controller model. Through the combination of sensor and controller predict, the simulation results show that the neural network predictive control has the characteristic of high speed and high control accuracy, and a strong ability to adapt and so on.
The Present Situation and Future Development of Electric Vehicles in China
Authors: Wei Min , Xie Yan , Jia Yu
Published: March 2012

As the represent of the new energy vehicles, electric vehicles dominate an irreplaceable position in solving energy crisis and protecting the environment. And some developed countries are investing heavily in the research and development of electric vehicles. In this paper, the domestic conditions of electric vehicles are introduced. And many topics about electric vehicle such as the prospect, industrial policies, key technologies and domestic charging network are further analyzed. Some thinking and suggestions relating to the development of electric vehicles are put forward at last.
The Simulation of a Cartridge Manipulator Based on Virtue Prototype
Authors: Yang Run Ze , Wang Yong Gang , Shu Xin , Shi Hua Feng
Published: March 2012

A new manipulator, designed by the authors, is used to push/pull the cartridge into/out of a drilling jig. It should carry out such actions as rotating, locking, unlocking and separating, etc. Cylindrical cam mechanism and spring steel ball mechanism are designed to fulfill the actions. To determine whether the design parameters are correct ADAMS is applied to the simulation analysis. The results illustrate that the manipulator can work reliably.
New Types of Veriﬁably Encrypted Signature Schemes
Authors: Kang Bao Yuan
Published: March 2012

A verifiably encrypted signature scheme involves a signer, a verifier, and an adjudicator. It can convince a verifier that a given ciphertext is an encryption of signature on a given message. At a later stage on agreed or in case of dispute, the adjudicator can extract and give the signer's signature to the verifier. In existing verifiably encrypted signatures, the adjudicator is assumed to be a trusted third party who will not conspire with either of the two parties involved. Obviously, this assumption is naive. In this paper, we propose two new types of verifiably encrypted signature schemes. They can resolve the problem that the adjudicator may collaborate with the verifier. We also analyze the security of the proposed schemes.
Derivation of Magnetostrictive Losses from Admittance Spectra
Authors: Tao Meng Lun , Zhuang Yuan , Chen Ding Fang , Ural Seyit O. , Lu Quan Guo , Uchino Kenji
Published: March 2012

There are three types of losses for magnetostrictors, elastic loss, magnetic loss and piezomagnetic coupling loss, similar to the loss mechanism of a piezoelectric (elastic, dielectric and piezoelectric losses) that our group has established recent years. By introducing these losses factors we can characterize magnetostrictive losses using complex parameters. Here we derived the relationship of mechanical quality factors and losses factor based on admittance spectra expression we have established previously. By measuring accurately the mechanical quality factors QA for the resonance and QB for the anti-resonance in the admittance/impedance curve, we can derive these three physical losses to characterize magnetostrictive hysteresis loss.
Characterization of Magnetostrictive Losses Using Complex Parameters
Authors: Tao Meng Lun , Zhuang Yuan , Chen Ding Fang , Ural Seyit O. , Lu Quan Guo , Uchino Kenji
Published: March 2012

Loss characterization in magnetostrictors is one of the key issues for realizing reliable magnetomechanical transducers. Concerning with the hysteresis minor loop within a relatively linear area of magnetostrictive curve, there are three types of losses, elastic loss, magnetic loss and piezomagnetic coupling loss, similar to the loss mechanism of a piezoelectric (elastic, dielectric and piezoelectric losses) that our group has established recent years. By measuring accurately the mechanical quality factors QA for the resonance and QB for the anti-resonance in the admittance/impedance curve, we can derive these three physical losses. By introducing these losses factors we can characterize magnetostrictive losses using complex parameters.
Reactive Diffusion at the Contact of a Solid Phase with the Solder Melt
Authors: Drápala Jaromír , Kubíček Petr , Harcuba Petr , Vodárek Vlastimil , Jopek Pavel , Petlák Daniel , Kostiuková Gabriela , Konečná Kateřina
Published: March 2012

Problems of reactive diffusion at the solid phase and melt contact are studied theoretically. The rate constant is a fundamental parameter characterizing the dissolving rate at a certain configuration of experiment. Relationships between the solid phase dissolving rate, i.e. the solid phase interface boundary movement in the melt, and rates of growth of intermetallic phases in the metal (Cu) are observed. This procedure enables the creation of surface and subsurface layers of regulated thickness in metallic materials by means of reactive diffusion. The main intention was an experimental study of copper dissolving in melts of various solder alloys and the related reactive diffusion. We used Sn, SnCu, SnAgCu, SnZn and SnIn alloys as a solder material. The problems that need to be solved preferentially are emphasized. It concerns especially the determination of the rate constant of dissolving and verifying whether the proposed model equations can be used for this constant determination in cases of cylindrical and planar dissolving. Rapid growth of phases in the metal (Cu) and determination of the thickness of layers with these phases pose considerable time demands to X-ray microanalyses (WDX, EDX, BSE, SEM) of specimens after their long-time heating.
Macro- and Microscale Fabrication by Field Assisted Nanoparticle Assembly - The Challenging Path from Science to Engineering
Authors: Falk G.
Published: March 2012

Local electrophoretic deposition of alumina nanoparticles under external DC electric field conditions with submerged impinging jet type capillaries arranged at ion exchange membrane substrates is presented. In order to evaluate particle deposition mechanisms a mathematical model is derived describing electroosmotic pumping of electrolyte through a micrometre scaled channel. The system is governed by surficial charge discontinuities and modeled by coupled mass balances, Ohmic law, Navier Stokes, and Nernst-Planck equations. Based on the boundary conditions of bulk convective electrodiffusion the effect of the imposed surface potential on the fluid flow behaviour and on particle tracing characteristics is studied by means of numerical analysis. The following findings have been obtained. At the corner edges of the charged surficial boundaries micro-vortices are generated to build up local stagnation points onto the modeled membrane surface. Particle tracing analysis reveal that the particle movement is caused by mass transport within the membrane directed velocity field to the stagnation point. The complex electrokinetics and electrohydro-dynamics suggest further investigations at membrane pore sizes in the range of the Debye-length to model the non-linear current-voltage characteristic that has already been experimentally proven for these kind of membrane EPD systems.
Microstructure and Properties of Hot Compacted Al-12 wt% Zn-3 wt% Mg-1.5 wt% Cu Melt Spun Ribbons
Authors: Lityńska-Dobrzyńska Lidia , Dutkiewicz Jan , Maziarz Wojciech , Faryna Marek , Stan Katarzyna , Kanciruk Adam
Published: March 2012

The alloys Al-12 wt % Zn-3 wt % Mg-1.5 wt % Cu with addition of Zr were melt spun and then hot pressed under 600 MPa pressure at 380 °C. Refinement of the microstructure and reduction of the volume fraction of the η (MgZn2) phase was observed in melt spun ribbon, as compared to the mould cast alloys. Good quality samples without pores and cracks obtained by hot pressing were composed of grains of size 0.2-0.5 µm. The particles of the η phase enriched in Zn, Mg and Cu were homogenously distributed in the matrix, while a few nanometres large precipitates of magnesium oxide were located at grain boundaries. Plate like precipitates of metastable h¢ phase appear after ageing at 120 °C and lead to microhardness increase up to about 195 HV as compared to 145 HV in pressed sample. Hot pressed ribbons showed compression strength of about 450 MPa which increased up to 630 MPa after ageing.
Structural and Mechanical Features of Rapidly Solidified Al-2Fe-2Ni-5Mg Alloy
Authors: Kula Anna , Blaz Ludwik , Sugamata Makoto
Published: March 2012

Rapid solidification (RS) of Al-2Fe-2Ni-5Mg alloy and following mechanical consolidation of powders by means of powder metallurgy (PM) methods was used with success to produce a bulk RS-material. RS powders were manufactured using an inert gas atomizing of the molten alloy and the spray deposition on the rotating water-cooled copper roll. Rods of 7 mm in diameter were received by means of the cold pressing of the flakes, vacuum degassing and hot extrusion method. For comparison purposes, the conventionally casted and hot extruded Al-2Fe-2Ni-5Mg alloy was tested as well. Mechanical properties of as-extruded materials were examined at 293 K – 873 K by compression tests performed at constant true strain rate of 5·10-3[s-1]. It was found that relatively high strength of as-extruded RS/PM material was accompanied by the high ductility of the samples deformed by hot compression tests. It was noticed that the most effective solution strengthening due to particles refining was observed at low deformation temperatures. Rising the test temperatures above ~ 420 K, was found to result in reduction of the flow stress to the values received for the industrial material (IM).The formation of coarse primary intermetallic compounds, which is typical for IM material, was effectively reduced for RS material. However some inhomogeneity of fine precipitates distribution in RS/PM material was observed. Nevertheless, it was considered that both solid solution hardening due to Mg addition and the dispersion strengthening due to refining of intermetallic compounds substantially increase the mechanical properties of the RS/PM material.
Transformation of Intermetallic Phases in 6066 Aluminium Alloy during its Homogenization
Authors: Mrowka-Nowotnik Grazyna
Published: March 2012

The effect of temperature and time of homogenization on intermetallic phase dissolution and transformation in 6066 alloy was studied. Microstructure examination has been carried out on the samples in the as-cast state and after different time of homogenization at 560°C using optical microscope - Nikon 300, scanning (SEM) electron microscopy combined with an energy dispersive X-ray microanalysis (EDS) and X-ray diffraction (XRD). The results show that the as-cast microstructure of 6066 contained β-Mg2Si, Si, Q-Al5Cu2Mg8Si6, b-Al5FeSi, α-Al(MnFe)Si and Al2Cu intermetallic phases. Significant changes in microstructure followed after homogenization process were revealed. The majority of Al2Cu, Q and Mg2Si particles have dissolved in a-Al, and plate-like b-Al5FeSi precipitates transformed into multiple, spherical α-Al(MnFe)Si.
HIV-1 Proteins Preferentially Activate Anti-Inflammatory M2-Type Macrophages
Authors: Chihara Takashi , Hashimoto Michihiro , Osman Abu , Hiyoshi-Yoshidomi Yuka , Suzu Ikuko , Chutiwitoonchai Nopporn , Hiyoshi Masateru , Okada Seiji , Suzu Shinya
Published: March 2012

HIV-1 proteins, including Tat, gp120, and Nef, activate macrophages (MΦ), which is consistent with the fact that HIV-1 infection is characterized by sustained immune activation. Meanwhile, MΦ are functionally classified into two types: proinflammatory M1-MΦ and anti-inflammatory M2-MΦ. We show that HIV-1 proteins, particularly Nef, preferentially activate M2-MΦ. Extracellular Tat, gp120, and Nef activated MAPK and NF-κB pathways in human peripheral blood monocyte-derived MΦ. However, the activation was marked in M-CSF–derived M2-MΦ but not GM-CSF–derived M1-MΦ. Nef was the most potent activator, and its signaling activation was comparable to that by TNF-α. Indeed, Nef was internalized more rapidly by M2-MΦ than by M1-MΦ. The myristoylation and proline-rich motif of Nef were responsible for the observed signaling activation. Consistent with the activation of MAPK/NF-κB pathways, Nef stimulated the production of a number of proinflammatory cytokines/chemokines by M2-MΦ. However, Nef reduced the expression of CD163 and phagocytosis, the characteristic markers of M2-MΦ, indicating that Nef drives an M2-like to M1-like phenotypic shift. Because the differentiation of most tissue MΦ depends on M-CSF and its receptor, which is the essential axis for the anti-inflammatory M2-MΦ phenotype, the current study reveals an efficient mechanism by which HIV-1 proteins, such as Nef, induce the proinflammatory MΦ.
Enhancing Immunostimulatory Function of Human Embryonic Stem Cell-Derived Dendritic Cells by CD1d Overexpression
Authors: Zeng Jieming , Shahbazi Mohammad , Wu Chunxiao , Toh Han Chong , Wang Shu
Published: March 2012

Human embryonic stem cell-derived dendritic cells (hESC-DCs) may potentially provide a platform to generate “off-the-shelf” therapeutic cancer vaccines. To apply hESC-DCs for cancer immunotherapy in a semiallogeneic setting, it is crucial for these cells to “jump-start” adaptive antitumor immunity before their elimination by host alloreaction. In this study, we investigated whether CD1d upregulation in hESC-DCs may exploit invariant NKT (iNKT) cell adjuvant activity and boost antitumor immunity. Using a baculoviral vector carrying the CD1d gene, we produced CD1d-overexpressing hESC-DCs and demonstrated that the upregulated CD1d was functional in presenting α-galactosylceramide for iNKT cell expansion. Pulsed with melanoma Ag recognized by T cell 1 peptide, the CD1d-overexpressing hESC-DCs displayed enhanced capability to prime CD8+ T cells without relying on α-galactosylceramide loading. Blocking the CD1d with Ab reduced the immunogenicity, suggesting the importance of hESC–DC and iNKT cell interaction in this context. The CD1d-overexpressing hESC-DCs also induced a proinflammatory cytokine profile that may favor the T cell priming. Moreover, a similar immunostimulatory effect was observed when the CD1d upregulation strategy was applied in human monocyte-derived dendritic cells. Therefore, our study suggests that the upregulation of CD1d in hESC-DCs provides a novel strategy to enhance their immunogenicity. This approach holds potential for advancing the application of hESC-DCs into human cancer immunotherapy.
A Deficiency in Nucleoside Salvage Impairs Murine Lymphocyte Development, Homeostasis, and Survival
Authors: Choi Onjee , Heathcote Dean A. , Ho Ka-Kei , Müller Phillip J. , Ghani Hazim , Lam Eric W.-F. , Ashton-Rickardt Philip G. , Rutschmann Sophie
Published: March 2012

The homeostasis of the immune system is tightly controlled by both cell-extrinsic and -intrinsic mechanisms. These regulators, not all known to date, drive cells in and out of quiescence when and where required to allow the immune system to function. In this article, we describe a deficiency in deoxycytidine kinase (DCK), one of the major enzymes of the nucleoside salvage pathway, which affects peripheral T cell homeostatic proliferation and survival. As a result of an N-ethyl-N-nitrosourea–induced mutation in the last α helix of DCK, a functionally null protein has been generated in the mouse and affects the composition of the hematopoietic system. Both B and T lymphocyte development is impaired, leading to a state of chronic lymphopenia and to a significant increase in the number of myeloid cells and erythrocytes. In the periphery, we found that mutant lymphocytes adopt a CD44highCD62Llow memory phenotype, with high levels of proliferation and apoptosis. These phenotypes are notably the result of a cell-extrinsic–driven lymphopenia-induced proliferation as wild-type cells transferred into DCK-deficient recipients adopt the same profile. In addition, DCK also regulates lymphocyte quiescence in a cell-intrinsic manner. These data establish dCK as a new regulator of hematopoietic integrity and lymphocyte quiescence and survival.
Expression of Natural Autoantibodies in MRL-lpr Mice Protects from Lupus Nephritis and Improves Survival
Authors: Mannoor Kaiissar , Matejuk Agata , Xu Yang , Beardall Michael , Chen Ching
Published: March 2012

Natural autoantibodies (NAA) and their associated B cells constitute a substantial proportion of the normal Ab and B cell repertoire. They often have weak reactivity toward a variety of self-Ags such as DNA, nucleoproteins, and phospholipids. It remains controversial whether NAA contribute to or protect from autoimmune diseases. Using site-directed transgenic (sd-tg) mice expressing a prototypic NAA, we investigated the effect of NAA and NAA-producing B cells in disease development in the autoimmune-prone MRL/MpJ-Faslpr (MRL-lpr) mice. We found that the expression of NAA in MRL-lpr mice prevented proteinuria and reduced kidney immune complex formation. The mice had significantly improved survival. Administration of the IgM NAA to MRL-lpr mice also delayed the onset of nephritis. The sd-tg MRL-lpr mice had decreased levels of anti-dsDNA Abs, anti-Hep2 nuclear Abs, and anti-Sm/ribonucleoprotein Abs. There is a shift in the IgG subclass profile from IgG2a and IgG3 to IgG1 in the sd-tg MRL-lpr mice. The CD4+ T cells from the sd-tg MRL-lpr mice had increased expression of the negative costimulatory molecule CTLA-4 and increased production of IL-10 as compared with those from the wild-type mice. Furthermore, the NAA B cells produced large amounts of IL-10 upon TLR stimulation. These results indicate that NAA and NAA-producing B cells play an important role in protection from lupus nephritis and suggest that the NAA B cells may have an immune regulatory function via the provision of IL-10.
Canonical Type I IFN Signaling in Simian Immunodeficiency Virus-Infected Macrophages Is Disrupted by Astrocyte-Secreted CCL2
Authors: Zaritsky Luna Alammar , Gama Lucio , Clements Janice E.
Published: March 2012

HIV-associated neurologic disorders are a mounting problem despite the advent of highly active antiretroviral therapy. To address mechanisms of HIV-associated neurologic disorders, we used an SIV pigtailed macaque model to study innate immune responses in brain that suppress viral replication during acute infection. We previously reported that during acute infection in brain, noncanonical type I IFN signaling occurs, where IFN-β mRNA is induced while IFN-α is simultaneously suppressed. Two downstream IFN-stimulated genes, MxA and TRAIL, also show differential expression patterns. In this study, we show that differential signaling is due to interactions between macrophages and astrocytes. Astrocytes produce high levels of CCL2 upon SIV infection, which binds to CCR2 receptors on macrophages, leading to a selective suppression of IFN-α and the IFN-stimulated gene TRAIL while simultaneously inducing IFN-β and MxA. The interactions between chemokine and cytokine pathways are a novel finding that may specifically occur in the CNS.
HLA-DQA2 and HLA-DQB2 Genes Are Specifically Expressed in Human Langerhans Cells and Encode a New HLA Class II Molecule
Authors: Lenormand Cedric , Bausinger Huguette , Gross Florence , Signorino-Gelo Francois , Koch Susanne , Peressin Maryse , Fricker Dominique , Cazenave Jean-Pierre , Bieber Thomas , Hanau Daniel , de la Salle Henri , Tourne Sylvie
Published: March 2012

The precise role of human epidermal Langerhans cells (LCs) in immune response is highly controversial. While studying the gene expression profile of these cells, we were intrigued to identify the HLA-DQB2 gene as potentially expressed in LCs. Despite a strong evolutionary conservation of their sequences, the concomitant expression of the poorly polymorphic HLA-DQA2/HLA-DQB2 genes, paralogous to the HLA-DQA1/HLA-DQB1 genes, has never been detected in any cell type. We confirmed by RT-PCR that the HLA-DQA2 and -DQB2 genes are both expressed in LCs, but not in monocyte-derived dendritic cells, or in blood CD1c+ or plasmacytoid dendritic cells. The presence of the HLA-DQβ2 chain in LCs could be demonstrated by Western blotting, whereas immunofluorescence revealed its localization in early endosomes. As in the case of other HLA class II molecules, the HLA-DQα2 and -DQβ2 chains formed heterodimers that had to associate with the invariant chain to reach endosomal compartments. HLA-DQα2/β2 heterodimers were expressed at the cell surface, where they could mediate staphylococcal superantigen stimulation of T cells. Interestingly, HLA-DQα2 and HLA-DQβ1 chains formed mixed heterodimers which efficiently left the endoplasmic reticulum. These observations strongly suggest that the poorly polymorphic HLA-DQA2 and -DQB2 genes should be considered to be of immunological importance. The HLA-DQα2/β2 molecules could influence the complexity of the repertoire of Ags presented by LCs.
A Second TCRδ Locus in Galliformes Uses Antibody-like V Domains: Insight into the Evolution of TCRδ and TCRμ Genes in Tetrapods
Authors: Parra Zuly E. , Mitchell Kevin , Dalloul Rami A. , Miller Robert D.
Published: March 2012

Analyses of the available avian genomes revealed the presence of a second TCRδ locus in the Galliformes. This second TCRδ locus is nonsyntenic to the conventional TCRα/δ and is unusual in that the V genes are more related to IgH V genes (VH) than to TCR V genes. The second TCRδ is not found in another avian lineage, the passerine zebra finch. Rather the finch’s conventional TCRα/δ locus contains VH genes that are expressed with the conventional Cδ gene, similar to what has been found in amphibians. A comparison between Galliformes and Passeriformes genomic organization suggests an origin of the second TCRδ in the former lineage involving gene duplication. Expression of these atypical TCRδ transcripts with a VH domain paired with Cδ was found in lymphoid tissues of both avian lineages. The configuration of the second TCRδ in chicken and turkey is reminiscent of the TCRδ duplication that is present in nonplacental mammals and provides insight into the origin of the uniquely mammalian TCRμ locus.
A universal carbonate ion effect on stable oxygen isotope ratios in unicellular planktonic calcifying organisms
Authors: Ziveri P. , Thoms S. , Probert I. , Geisen M. , Langer G.
Published: March 2012

Abstract. The oxygen isotopic composition (δ18O) of calcium carbonate of planktonic calcifying organisms is a key tool for reconstructing both past seawater temperature and salinity. The calibration of paloeceanographic proxies relies in general on empirical relationships derived from field experiments on extant species. Laboratory experiments have more often than not revealed that variables other than the target parameter influence the proxy signal, which makes proxy calibration a challenging task. Understanding these secondary or "vital" effects is crucial for increasing proxy accuracy. We present data from laboratory experiments showing that oxygen isotope fractionation during calcification in the coccolithophore Calcidiscus leptoporus and the calcareous dinoflagellate Thoracosphaera heimii is dependent on carbonate chemistry of seawater in addition to its dependence on temperature. A similar result has previously been reported for planktonic foraminifera, supporting the idea that the [CO32−] effect on δ18O is universal for unicellular calcifying planktonic organisms. The slopes of the δ18O/[CO32−] relationships range between –0.0243‰ (μmol kg−1)−1 (calcareous dinoflagellate T. heimii) and the previously published –0.0022‰ (μmol kg−1)−1 (non-symbiotic planktonic foramifera Orbulina universa), while C. leptoporus has a slope of –0.0048 ‰ (μmol kg−1)−1. We present a simple conceptual model, based on the contribution of δ18O-enriched HCO3− to the CO32− pool in the calcifying vesicle, which can explain the [CO32−] effect on δ18O for the different unicellular calcifiers. This approach provides a new insight into biological fractionation in calcifying organisms. The large range in δ18O/[CO32−] slopes should possibly be explored as a means for paleoreconstruction of surface [CO32−], particularly through comparison of the response in ecologically similar planktonic organisms.