bluuebunny/crossref_metadata_2025 huggingface dataset:
CALCULATION OF THE ULTIMATE BEARING CAPACITY OF SOIL SLOPE BASED ON THE UNIFIED STRENGTH THEORY
Authors: LIAO HONGJIAN , MA ZONGYUAN , SU LIJUN
Published: March 2009

At present, the failure criteria used in calculating the ultimate bearing capacity of soil slope are the Tresca and Mohr-Coulomb criteria. But the results are conservative and the potential strength of soil mass cannot be utilized sufficiently because these two criteria do not take into account the effect of the intermediate principal stress. In this paper the unified strength theory was used to analyze the ultimate bearing capacity of soil slope. The formula for calculating the ultimate bearing capacity of soil slope using the unified strength theory was established. At the end, a case history was analyzed and it indicated that the result of the unified strength theory is larger than that of the Mohr-Coulomb criterion. This indicates that calculation of ultimate bearing capacity of soil slope with the unified strength theory can sufficiently exploit the strength of material. Therefore, the calculation of ultimate bearing capacity of the soil slope based on the unified strength theory will be of great significance in future applications.
A PROCESS MAP FOR SEQUENTIAL COMPRESSION-BACKWARD EXTRUSION OF AZ31 MG ALLOYS AT WARM TEMPERATURS
Authors: YOON DUK-JAE , KIM EUNG-ZOO , CHO CHONG-DU , LEE YONG-SHIN
Published: March 2009

This paper is concerned with development of a process map for sequential compression-backward extrusion of bulk AZ31 Mg alloy at the warm temperatures. In experiments, metal flows and crack initiations are carefully investigated and formability is examined systematically for various forming conditions such as forming temperature, punch speed, and a gap between a specimen and die. Then, a process map for the sequential compression-backward extrusion of bulk AZ31 Mg alloy at the warm temperature is proposed. In order to further understand deformation behaviors and damage evolution during warm forming process, thermo mechanical finite element analyses coupled with damage evolutions are carried out. In general, finite element predictions support experimental observation. Finally, it is concluded that the process map, proposed for the sequential compression-backward extrusion of AZ31 Mg alloy, is valid.
STUDY ON CORRELATION BETWEEN SHEAR WAVE VELOCITY AND GROUND PROPERTIES FOR GROUND LIQUEFACTION INVESTIGATION OF SILTS
Authors: CHE AILAN , LUO XIANQI , QI JINGHUA , WANG DEYONG
Published: March 2009

Shear wave velocity (Vs) of soil is one of the key parameters used in assessment of liquefaction potential of saturated soils in the base with leveled ground surface; determination of shear module of soils used in seismic response analyses. Such parameter can be experimentally obtained from laboratory soil tests and field measurements. Statistical relation of shear wave velocity with soil properties based on the surface wave survey investigation, and resonant column triaxial tests, which are taken from more than 14 sites within the depth of 10 m under ground surface, is obtained in Tianjin (China) area. The relationship between shear wave velocity and the standard penetration test N value (SPT-N value) of silt and clay in the quaternary formation are summarized. It is an important problem to research the effect of shear wave velocity on liquefaction resistance of saturated silts (sandy loams) for evaluating liquefaction resistance. According the results of cyclic triaxial tests, a correlation between liquefaction resistance and shear wave velocity is presented. The results are useful for ground liquefaction investigation and the evaluation of liquefaction resistance.
MICROSTRUCTURE AND CRYSTALLOGRAPHIC TEXTURE OF STRIP-CAST FE-3.2%SI STEEL SHEET
Authors: XU Y.B. , YU Y.M. , CAO G.M. , LI C.S. , WANG G.D. , JIANG Z.Y.
Published: March 2009

Fe -3.2% Si steel strips were produced using vertical type twin casting process, and the changes of microstructure and texture trough thickness direction were analyzed. The equiaxed grains of approximately 44.6µm were observed in the center layer, the great mass of columnar dendrite was formed near the surface, and the dendrite truck mainly developed in the transverse direction with respect to the casting direction of about 45° or less. From the subsurface to the center, the volume fraction of the Goss texture (110)[001] gradually decreases. The Goss {110} <001> components at the surface are two times those at the center layer, the {001} <100> components are three times those at the center layer, and the overall texture components are similar to that of the hot-rolled oriented silicon steel strip. The minor α texture could be found from the φ2=45° sections of ODF, and there is no remarkable composition segregation of Si element in the thickness direction of thin strip.
FINITE ELEMENT SIMULATION OF PORE CLOSING DURING CYLINDER UPSETTING
Authors: LEE MIN CHEOL , JANG SUNG MIN , CHO JU HYUN , JOUN MAN SOO
Published: March 2009

Three-dimensional precision simulation of pore closing during cylinder upsetting is carried out in this paper. A matrix of pores on the longitudinal section of a cylindrical material is traced at the same time. Various ratios of pore-to-cylinder diameter are tested to reveal their effect on the pore closing phenomena. Hydrostatic pressure and effective strain as well as the order of pore closing are investigated in detail to find out major factors affecting pore closing. It is shown that the effective strain has a strong relationship with the pore closing phenomena and that the finishing time of pore closing increases as the ratio of pore-to-cylinder diameter increases but that the pore size effect becomes negligible if the ratio exceeds a critical value. An intelligent metal forming simulator AFDEX 3D is used.
NUMERICAL SIMULATIONS OF THE INFLUENCE OF STRIKER BAR LENGTH ON SHPB MEASUREMENTS
Authors: SHU DONG WEI , LUO CHUN QI , LU GUO XING
Published: March 2009

Split Hopkinson Pressure Bar (SHPB) has become a frequently used technique for measuring uni-axial compressive stress-strain relationship of various engineering materials under high strain rates. The pulse shape generated in the incident bar is sensitive to the length of the striker bar. In this paper, a finite element simulation of a Split Hopkinson Pressure Bar is performed to estimate the effect of varying length of striker bar on the stress-strain relationship of a material. A series of striker bars with different lengths, from 200mm to 350mm, are employed to obtain the stress-strain response of AL6061-T6 in both simulation and experiment. A comparison is made between the experimental and the computed stress-strain curves. Finally the influence of variation of striker bar length on the sample's stress-strain response is presented.
QUANTITATIVE RELATIONSHIPS BETWEEN MICROSTRUCTURAL AND MECHANICAL PARAMETERS OF STEELS WITH DIFFERENT CARBON CONTENT
Authors: PIETRZAK KRYSTYNA , KLASIK ADAM , KOWALEWSKI ZBIGNIEW , RUDNIK DARIUSZ
Published: March 2009

The steels of different carbon content were tested with respect to their microstructural and selected mechanical parameters variations. The original combinatorial method, based on the phase quanta theory, was applied in the quantitative metallographic assessment. Hence, the adequate geometrical parameters of steel microstructure were possible to be determined. Moreover, the selected mechanical parameters of the materials were evaluated using non-destructive and destructive methods. The results enabled to formulate some significant quantitative relationships between microstructure and mechanical parameters.
DYNAMICS BEHAVIOR ANALYSIS OF GLOBULAR PARTICLE IN RHEOLOGY MATERIAL WITH CONTROLLED SOLID FRACTION
Authors: KWON KI-YOUNG , KANG CHUNG-GIL , LEE SANG-MAE
Published: March 2009

Semi-solid forging process has many advantages such as long die life, good mechanical properties and energy savings. But rheology material has complex characteristics, i.e., thixotropic behavior. Also, difference of the particle velocity between solid and liquid phase in the semi-solid state material causes a liquid segregation and specific stress variation. A number of simulation tools have been attempted for analyzing these behaviors of rheology material. However, general plastic or fluid dynamic analysis is not suitable. Therefore, we set up the stress equation to include viscosity, in order for investigating on how the moving behavior the solid particle in the rheology material during forging process is affected by viscosity, temperature, and solid fraction. In this study, a dynamics simulation was performed for the control of liquid segregation and the prediction of stresses on particles by changing forming velocity and viscosity in a compression experiment as part of a study on the analysis of the rheology aluminum forming process.
A STUDY ON IMPACT DEFORMATION AND TRANSFORMATION BEHAVIOR OF TRIP STEEL BY FINITE ELEMENT SIMULATION AND EXPERIMENT
Authors: IWAMOTO TAKESHI , SAWA TOSHIYUKI , CHERKAOUI MOHAMMED
Published: March 2009

Due to strain-induced martensitic transformation (SIMT), the strength, ductility and toughness of TRIP steel are enhanced. The impact deformation behavior of TRIP steel is very important because it is investigated to apply it for the shock absorption member in automobile industries. However, its behavior is still unclear since it is quite difficult to capture the transformation behavior inside the materials. There are some opinions that the deformation characteristics are not mainly depending on the martensitic transformation due to heat generation by plastic work. Here, the impact compressive deformation behavior of TRIP steel is experimentally studied by Split Hopkinson Pressure Bar (SHPB) method at room temperature. In order to catch SIMT behavior during impact deformation, volume resistivity is measured and a transient temperature is captured by using a quite thin thermocouple. Then, a finite element simulation with the constitutive model for TRIP steel is performed. The finite element equation can be derived from the rate form of principle of virtual work based on the implicit time integration scheme. Finally, the results between the computation and experiment are compared to confirm the validity of computational model.
MICRO FORMING OF GLASS MICROLENS ARRAY USING AN IMPRINTED AND SINTERED TUNGSTEN CARBIDE MICRO MOLD
Authors: HAN JEONGWON , MIN BYUNG-KWON , KANG SHINILL
Published: March 2009

Glass microlens array with lens diameter under 100 µm was replicated by micro thermal forming process using a tungsten carbide micro mold which was imprinted and sintered from an original master. The original master was fabricated by photolithography and thermal reflow process. The effects of forming process conditions on the form accuracy and the surface roughness of the micro formed glass microlens array were examined and analyzed. Finally, to verify the effectiveness of the proposed process, glass microlens array for the purpose of laser beam focusing was designed and fabricated, and a focused laser beam profile using the fabricated microlens array was measured and analyzed.
INCREMENTAL SHEET FORMING WITH LOCAL HEATING FOR LIGHTWEIGHT HARD-TO-FORM MATERIAL
Authors: HINO R. , YOSHIDA F. , NAGAISHI N. , NAKA T.
Published: March 2009

A new incremental sheet forming technology with local heating is proposed to form lightweight hard-to-form sheet metals such as aluminum-magnesium alloy (JIS A5083) sheet or magnesium alloy (JIS AZ31) sheet. The newly designed forming tool has a built-in heater to heat the sheet metal locally and increase the material ductility around the tool-contact point. Incremental forming experiments of A5083 and AZ31 sheets are carried out at several tool-heater temperatures ranging from room temperature to 873K using the new forming method. The experimental results show that the formability of A5083 and AZ31 sheets increases remarkably with increasing local-heating temperature. In addition, springback of formed products decreases with increasing local-heating temperature. The developed incremental sheet forming method with local heating has great advantages in not only formability but also shape fixability. It is an effective forming method for lightweight hard-to-form sheet metal for small scale productions.
COLD BUTT JOINING OF LIGHT METAL SHEET BY SHOT PEENING
Authors: HARADA YASUNORI , KOBAYASHI YUJI
Published: March 2009

Aluminum and magnesium materials are very attractive for light weight applications. However, their use is complicated by the fact that dissimilar metals are joined by fusion welding. In the present study, the cold butt joining of light metal sheet with dissimilar material sheet by shot peening was investigated. The shot peening process is widely used to improve the performance of engineering components. In this process the substrate undergoes a large plastic deformation near its surface when hit by many shots. The substrate material close to the surface flows during shot peening. When the dissimilar metal sheets with notched edges are connected without a level difference and then the connection is shot peened, the sheets can be joined by the plastic flow generated by the large plastic deformation during shot peening. In this experiment, an air-type shot peening machine was used. The influences of peening time and shot material on joinability were mainly examined. The joinability was evaluated by tensile test. The joint strength increased with the amount of plastic flow. It was found that the present method can be used to enhance the butt joining of the light metal sheets with the dissimilar material sheets.
INVESTIGATION ON THERMAL PROPERTIES OF Al/SiCp METAL MATRIX COMPOSITE BASED ON FEM ANALYSIS
Authors: YU EUSUN , SUN JEONG-YUN , CHUNG HEE-SUK , OH KYU HWAN
Published: March 2009

Computational simulations on the thermal analysis of metal matrix composite (MMC) composed of Al and SiC were performed in extended areas of SiC volume fraction. Due to the experimental limitations, only the narrow range of SiC volume fraction has been examined. Through the simulation, which enables current experimental situation to extend, we attempted to explore the dependencies of thermal and mechanical properties on changing the value of volume fraction ( V f ). To calculate the coefficient of thermal expansion (CTE), variables with temperature and V f were given in a range from 25°C to 100°C and 0 to 100%, respectively. We obtained quantitative results including CTE as a function of V f , which are in a good agreement with previous experimental reports. Furthermore, the stress analysis about thermally expanded MMC was performed. At low volume fraction of SiC , the thermal expansion caused the tensile stress at Al near the interface. However, as the volume fraction of SiC was increased, the stress turned to be compressive, it's because the linked SiC particles contracted the expansion of Al . The MMC of Al matrix face centered cubic site SiC particles has more stress evolutions than the MMC of Al matrix simple cubic site SiC particles at same volume fraction.
A NEW IMMERSED BOUNDARY-LATTICE BOLTZMANN METHOD AND ITS APPLICATION TO INCOMPRESSIBLE FLOWS
Authors: SHU CHANG , WU JIE
Published: March 2009

A new immersed boundary-lattice Boltzmann method (IB-LBM) is presented in this work. In the conventional IB-LBM, the restoring force is pre-calculated, which makes the non-slip boundary condition to be only approximately satisfied. As a result, the streamline penetration to the solid body occurs. In the present study, the velocity correction (restoring force) is considered as unknown. It is determined in such a way that the non-slip boundary condition is enforced. As compared with conventional IB-LBM, the solution procedure of current IB-LBM is almost the same except that the non-slip boundary condition is guaranteed in the present scheme while it is only approximately satisfied in the conventional scheme. Numerical results for simulation of flows over fixed circular cylinders showed that the present method can provide accurate solutions without any streamline penetration phenomenon.
THE EFFECTS OF TEMPERATURE ON HEAT TRANSFER IN MICROCHANNEL FLOWS
Authors: CHEN C. S.
Published: March 2009

The physical properties of incompressible fluids used in heat exchangers, such as viscosity and thermal conductivity, change considerably with temperature during their normal operating conditions. This study investigates the heat transfer characteristics of microchannel flows by taking these variations into account. Our results demonstrate that the temperature effects are significant and must be taken into account if accurate predictions are to be obtained.
CHARACTERIZATION OF THE PULSED NEEDLE-FREE MICRO-INJECTOR IN THE MEDICAL DELIVERY SYSTEM
Authors: WANG MUH-RONG , CHIU CHUN-HSIEN
Published: March 2009

This paper describes the development of the needle-free injection with a pulsed micro-injector. The novel injection system consists of a micro-injector, a solenoid valve with an electron-control system and a high pressure liquid supply system. The diameters of the orifice are 200µm~ 300µm. The performance of both pulsed and continuous injections is characterized. Results show that the mass flow rate is increased linearly for the liquid pressure ranging from 50bar to 125bar. The jet velocity increases from 50.6m/s to 104m/s as the liquid pressure increases from 50bar to 125bar. Penetration test to the soft solid materials shows that the penetration depth is increased from 2mm to 7mm depending on the injection power under single pulsed injection. It is believed that the technique will be useful for the drug delivery as well as the localized tumor treatment.
INVESTIGATIONS ON THE DRAG REDUCTION OF HIGH-SPEED NATURAL SUPERCAVITATION BODIES
Authors: YI WENJUN , TAN JUNJIE , XIONG TIANHONG
Published: March 2009

In order to investigate the drag reduction characteristics of a high-speed body with supercavitation shape, four types of typical disk cavitator models with different parameters were designed and tested. By measuring the velocity decrease histories during supercavitating flow experiments, the average drag coefficients were determined, which allows analysis and comparison of the influence of cavitator diameter, projectile aspect ratio, and cavitation number on the drag reduction. Based on the experimental results, numerical simulation of the drag reduction of supercavitation body was also carried out using a commercial software FLUENT6.2, and the results obtained agree well with the experimental data. Moreover, it is shown that the drag coefficients of the four bodies are in inverse ratio to the head area of cavitator when operating under natural supercavitating flow condition, and the smaller drag coefficient can be obtained by increasing the slender ratio of the bodies. Therefore, higher aspect ratio reduces drag coefficient, with the reduction of more than 95% under certain condition of cavitation number and supercaviation shape.
FLUID-STRUCTURE INTERACTION ANALYSIS OF A HIGH-ASPECT-RATIO WING CONSIDERING STRUCTURAL NONLINEARITY
Authors: KIM KYUNG-SEOK , LIM IN-GYU , LEE IN , YOO JAE-HAN
Published: March 2009

In this research, fluid-structure interaction problem including geometric structural nonlinearity is studied for a high-aspect-ratio wing. When a high-aspect-ratio wing structure is interacted with external airload, geometric structural nonlinearity can be caused by large deflection of a wing. For the investigation of such a fluid-structure interaction problem, the transonic small disturbance theory for the aerodynamic analysis and the large deflection beam theory for the structural analysis are used, respectively. For the coupling between fluid and structure, the transformation of a displacement from the structural mesh to the aerodynamic grid is performed by a shape function which is used for the finite element and the inverse transformation of force by work equivalent load method. Static deformations in the vertical and twist deflections caused by gravity loading are compared with experimental results. Also, static aeroelastic analysis results are compared with experimental data. From the analysis results, effects of structural nonlinearity on static aeroelastic characteristics are investigated.
MULTISCALE STATISTICAL MODEL OF FULLY-DEVELOPED TURBULENCE PARTICLE ACCELERATIONS
Authors: CHEN WEN , SUN HONGGUANG
Published: March 2009

Based on the experimental measurement results of fluid particle transverse accelerations in fully developed pipe turbulence published in Nature (2001) by La Porta et al, the present authors recently develop a multiscale statistical model which considers both normal diffusion in molecular scale and anomalous diffusion in vortex scale. This model gives rise to a new probability density function, called Power-Stretched Gaussian Distribution model (PSGD). In this study, we make a further comparison of this statistical distribution model with the well-known Lévy distribution, Tsallis distribution and stretched-exponential distribution. Our model is found to have the following merits: 1) fewer parameters, 2) better fitting with experimental data, 3) more explicit physical interpretation.
SURFACE-DIRECTED SPINODAL DECOMPOSITION: LATTICE MODEL VERSUS GINZBURG–LANDAU THEORY
Authors: BINDER KURT , DAS SUBIR K. , HORBACH JÜRGEN
Published: March 2009

When a binary mixture is quenched into the unstable region of the phase diagram, phase separation starts by spontaneous growth of long-wavelength concentration fluctuations ("spinodal decomposition"). In the presence of surfaces, the latter provide nontrivial boundary conditions for this growth. These boundary conditions can be derived from lattice models by suitable continuum approximations. But the lattice models can also be simulated directly, and thus used to clarify the conditions under which the Ginzburg–Landau type theory is valid. This comparison shows that the latter is accurate only in the immediate vicinity of the bulk critical point, if thermal fluctuations can also be neglected (true for the late stages of phase separation). In contrast, a local kinetic molecular field theory can take full account of nonlinearities and of rapid concentration variations, and thus has a much wider validity. This enables the detailed study of phase separation processes in thin films of solid binary alloys. However, the extension to spinodal decomposition in fluid binary systems (which can be simulated by brute force large scale molecular dynamics methods, of course) remains an unsolved challenge.
Effects of repeated restraint stress on gastric motility in rats
Authors: Zheng Jun , Dobner Anthony , Babygirija Reji , Ludwig Kirk , Takahashi Toku
Published: March 2009

In our daily life, individuals encounter with various types of stress. Accumulation of daily life stress (chronic stress) often causes gastrointestinal symptoms and functional gastrointestinal diseases. Although some can adapt toward chronic stress, the adaptation mechanism against chronic stress remains unknown. Although acute stress delays gastric emptying and alters upper gastrointestinal motility, effects of chronic stress on gastric motility still remain unclear. We investigated the effects of acute (single stress) and chronic (repeated stress for 5 consecutive days) stress on solid gastric emptying and interdigestive gastroduodenal contractions in rats. It is well established that acute restraint stress inhibits solid gastric emptying via central corticotropin-releasing factor (CRF). To investigate whether the sensitivity to CRF is altered following chronic stress, CRF was administered intracisternally. Ghrelin is involved in regulating gastric emptying and upper gastrointestinal motility in rodents. The changes in plasma active ghrelin levels and mRNA expression in the stomach were studied following chronic stress. To evaluate the effects of chronic stress on the hypothalamus-pituitary-adrenal (HPA) axis, plasma corticosterone levels were also measured. Delayed gastric emptying observed in acute stress was completely restored following chronic stress. Acute stress abolished gastric phase III-like contractions, without affecting duodenal phase III-like contractions in the interdigestive state. Impaired gastric phase III-like contractions were also restored following chronic stress. Plasma ghrelin levels and ghrelin mRNA expression were increased significantly after chronic stress. Intracisternal injection of CRF delayed gastric emptying and impaired gastric motility in rats who received chronic stress. Plasma corticosterone concentrations were no more elevated following chronic stress. The restored gastric emptying following chronic stress was antagonized by the administration of ghrelin receptor antagonists. The adaptation mechanism may involve upregulation of ghrelin expression and attenuation of the HPA axis. In contrast, the sensitivity to central CRF remained unaltered following chronic stress in rats.
Angiotensin II type 1 receptor blocker attenuates the activation of ERK and NADPH oxidase by mechanical strain in mesangial cells in the absence of angiotensin II
Authors: Yatabe Junichi , Sanada Hironobu , Yatabe Midori Sasaki , Hashimoto Shigeatsu , Yoneda Minoru , Felder Robin A. , Jose Pedro A. , Watanabe Tsuyoshi
Published: March 2009

It has been reported that mechanical strain activates extracellular signal-regulated protein kinases (ERK) without the involvement of angiotensin II (Ang II) in cardiomyocytes. We examined the effects of mechanical strain on ERK phosphorylation levels in the absence of Ang II using rat mesangial cells. The ratio of phosphorylated ERK (p-ERK) to total ERK expression was increased by cyclic mechanical strain in a time- and elongation strength-dependent manner. With olmesartan [Ang II type 1 receptor (AT1R) antagonist] pretreatment, p-ERK plateau levels decreased in a dose-dependent manner (EC50= 1.3 × 10−8M, maximal inhibition 50.6 ± 11.0% at 10−5M); a similar effect was observed with RNA interference against Ang II type 1A receptor (AT1AR) and Tempol, a superoxide dismutase mimetic. In addition to the inhibition of p-ERK levels, olmesartan blocked the increase in cell surface and phosphorylated p47phoxinduced by mechanical strain and also lowered the mRNA expression levels of NADPH oxidase subunits. These results demonstrate that mechanical strain stimulates AT1R to phosphorylate ERK in mesangial cells in the absence of Ang II. This mechanotransduction mechanism is involved in the oxidative stress caused by NADPH oxidase and is blocked by olmesartan. The inverse agonistic activity of this AT1R blocker may be useful for the prevention of mesangial proliferation and renal damage caused by mechanical strain/oxidative stress regardless of circulating or tissue Ang II levels.
Insulin uptake across the luminal membrane of the rat proximal tubule in vivo and in vitro
Authors: Kolman Pavel , Pica Angelo , Carvou Nicolas , Boyde Alan , Cockcroft Shamshad , Loesch Andrew , Pizzey Arnold , Simeoni Mariadelina , Capasso Giovambattista , Unwin Robert J.
Published: March 2009

We visualized insulin uptake in vivo across the apical membrane of the rat proximal tubule (PT) by confocal microscopy; we compared it with in vitro findings in a rat PT cell line (WKPT) using fluorescence microscopy and flow cytometry. Surface tubules were observed in vivo with a 633-nm single laser-illuminated real-time video-rate confocal scanning microscope in upright configuration for optical sectioning below the renal capsule. Fields were selected containing proximal and distal tubules; Cy5-labeled insulin was injected twice (the second time after ∼140 min) into the right jugular vein, and the fluorescence signal (at 650–670 nm) was recorded. Fluorescence was detected almost immediately at the brush-border membrane (BBM) of PT cells only, moving inside cells within 30–40 min. As a measure of insulin uptake, the ratio of the fluorescence signal after the second injection to the first doubled (ratio: 2.11 ± 0.26, mean ± SE, n = 10), indicating a “priming,” or stimulating, effect of insulin on its uptake mechanism at the BBM. This effect did not occur after pretreatment with intravenous lysine (ratio: 1.03 ± 0.07, n = 6; P < 0.01). Cy2- or Cy3-labeled insulin uptake in a PT cell line in vitro was monitored by 488-nm excitation fluorescence microscopy using an inverted microscope. Insulin localized toward the apical membrane of these cells. Semiquantitative analysis of insulin uptake by flow cytometry also demonstrated a priming effect (upregulation) on insulin internalization in the presence of increasing amounts of insulin, as was observed in vivo; moreover, this effect was not seen with, or affected by, the similarly endocytosed ligand β2-glycoprotein.
Contrast angiography of the rat renal microcirculation in vivo using synchrotron radiation
Authors: Eppel Gabriela A. , Jacono David Lo , Shirai Mikiyasu , Umetani Keiji , Evans Roger G. , Pearson James T.
Published: March 2009

We have developed a new method for contrast microangiography of the rat renal circulation using synchrotron radiation. The method was applied to determine responses of the renal arterial vasculature to angiotensin II and electrical stimulation of the renal nerves (RNS). Iodinated contrast agent was administered directly into the renal artery of pentobarbital-anesthetized rats before and during 1) intravenous infusion of angiotensin II (1.6 μg·kg−1·min−1) or 2) its vehicle, or 3) RNS at 2 Hz. Images were obtained at 30 Hz, before and during these treatments, and vascular caliber was determined by use of a newly developed algorithm described herein. Up to four levels of branching could be observed simultaneously along the arterial tree, comprising vessels with resting diameter of 28–400 μm. Vessel diameter was not significantly altered by vehicle infusion (+3.1 ± 3.5% change) but was significantly reduced by angiotensin II (−24.3 ± 3.4%) and RNS (−17.1 ± 3.8%). Angiotensin II-induced vasoconstriction was independent of vessel size, but RNS-induced vasoconstriction was greatest in vessels with a resting caliber of 100–200 μm and least in vessels with a resting caliber 40–100 μm. In conclusion, the method we describe herein provides a new approach for assessing responses of the renal arterial circulation to vasoactive factors along several orders of branching.
NMDA Receptor Activation by Spontaneous Glutamatergic Neurotransmission
Authors: Espinosa Felipe , Kavalali Ege T.
Published: March 2009

Under physiological conditions N-methyl-d-aspartate (NMDA) receptor activation requires coincidence of presynaptic glutamate release and postsynaptic depolarization due to the voltage-dependent block of these receptors by extracellular Mg2+. Therefore spontaneous neurotransmission in the absence of action potential firing is not expected to lead to significant NMDA receptor activation. Here we tested this assumption in layer IV neurons in neocortex at their resting membrane potential (approximately −67 mV). In long-duration stable recordings, we averaged a large number of miniature excitatory postsynaptic currents (mEPSCs, >100) before or after application of dl-2 amino 5-phosphonovaleric acid, a specific blocker of NMDA receptors. The difference between the two mEPSC waveforms showed that the NMDA current component comprises ∼20% of the charge transfer during an average mEPSC detected at rest. Importantly, the contribution of the NMDA component was markedly enhanced at membrane potentials expected for the depolarized up states (approximately −50 mV) that cortical neurons show during slow oscillations in vivo. In addition, partial block of the α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor component of the mEPSCs did not cause a significant reduction in the NMDA component, indicating that potential AMPA receptor-driven local depolarizations did not drive NMDA receptor activity at rest. Collectively these results indicate that NMDA receptors significantly contribute to signaling at rest in the absence of dendritic depolarizations or concomitant AMPA receptor activity.
Hippocampal Neural Assemblies and Conscious Remembering
Authors: Shirvalkar Prasad R.
Published: March 2009

The hippocampal formation is needed to encode episodic memories, which may be consciously recalled at some future time. This review examines recent advances in understanding recollection in the context of spatiotemporally organized relational memory coding and discusses predictions and challenges for future research on conscious remembering.
Increased Failure Rate of Autologous Chondrocyte Implantation after Previous Treatment with Marrow Stimulation Techniques
Authors: Minas Tom , Gomoll Andreas H. , Rosenberger Ralf , Royce Ronald O. , Bryant Tim
Published: March 2009

Background

Marrow stimulation techniques such as drilling or microfracture are first-line treatment options for symptomatic cartilage defects. Common knowledge holds that these treatments do not compromise subsequent cartilage repair procedures with autologous chondrocyte implantation.

Hypothesis

Cartilage defects pretreated with marrow stimulation techniques will have an increased failure rate.

Study Design

Cohort study; Level of evidence, 2.

Methods

The first 321 consecutive patients treated at one institution with autologous chondrocyte implantation for full-thickness cartilage defects that reached more than 2 years of follow-up were evaluated by prospectively collected data. Patients were grouped based on whether they had undergone prior treatment with a marrow stimulation technique. Outcomes were classified as complete failure if more than 25% of a grafted defect area had to be removed in later procedures because of persistent symptoms.

Results

There were 522 defects in 321 patients (325 joints) treated with autologous chondrocyte implantation. On average, there were 1.7 lesions per patient. Of these joints, 111 had previously undergone surgery that penetrated the subchondral bone; 214 joints had no prior treatment that affected the subchondral bone and served as controls. Within the marrow stimulation group, there were 29 (26%) failures, compared with 17 (8%) failures in the control group.

Conclusion

Defects that had prior treatment affecting the subchondral bone failed at a rate 3 times that of nontreated defects. The failure rates for drilling (28%), abrasion arthroplasty (27%), and microfracture (20%) were not significantly different, possibly because of the lower number of microfracture patients in this cohort (25 of 110 marrow-stimulation procedures). The data demonstrate that marrow stimulation techniques have a strong negative effect on subsequent cartilage repair with autologous chondrocyte implantation and therefore should be used judiciously in larger cartilage defects that could require future treatment with autologous chondrocyte implantation.
Effect of Matrix Ductility on Elastic—Plastic Interlaminar Stresses in Thermoplastic AS4/PEEK Composite Laminates
Authors: Min Shen  , Jingwei Tong
Published: March 2009

Using three orthotropic elastic finite element models with elastic and elastic—plastic PEEK resin-rich layers included, three-dimensional elastic—plastic analyses of interlaminar stresses in AS4/PEEK thermoplastic composites under tensile loading for [0/90]s, [0/±45/90] 2s, and [±25]s4 laminates are presented, in order to ascertain the influence of matrix plasticity upon the free-edge effect in AS4/PEEK laminate. The nonlinear tension behaviors of the whole laminate are predicted by means of the above numerical models and compared with experimental results in detail. The applicability of these FE models with elastic—plastic resin layers models is discussed.
Parametric Study on the Fabrication of Clay-containing Thermosetting Nanocomposites
Authors: Park Jin Y. , Davis Tye B. , Sullivan Paul L.
Published: March 2009

Clay/epoxy nanocomposites were fabricated using shear mixing to determine the increase in mechanical properties over those of pure epoxy. The effectiveness of the fabrication process was improved and explained in detail to provide composites researchers with the ability to fabricate thermosetting nanocomposites efficiently. The effects of process variables on the resulting nanocomposite materials were determined through repeated fabrication and testing. The effects of void removal and shear mixing variables were determined through alteration of the fabrication process. When the effects of the process variables had been determined, a fabrication procedure based on the results was used to fabricate nanocomposites containing 2, 4, and 6% nanoparticles by weight. Tensile tests were performed to determine the extensional moduli and tensile strengths of nanocomposite samples. Experimental values were compared to the developed mathematical models as well as to the values of the neat resin.
Effects of Carbon Nanotubes Geometrical Distribution on Electrical Percolation of Nanocomposites: A Comprehensive Approach
Authors: Asiaei Sassan , Akbar Afaghi Khatibi  , Baniasadi Majid , Safdari M.
Published: March 2009

The main objective of this study was to study the effects of length, alignment and diameter distribution of the carbon nanotubes (CNTs) on the percolation threshold of nanocomposites using computational simulations. Furthermore, the effects of the aforementioned parameters on the efficiency of the produced networks are investigated. The best distribution for optimum connectivity and the lowest CNTs concentration for the onset of percolation is determined via analyzing the geometrical characteristics of carbon nanotubes. The critical volume fraction of CNTs for percolation was found to be 0.1% while the mean number of bonds per object was 1.3 at the best distribution condition. The results from this study are compared to available experimental data and good agreement was found.
Properties of Fiber Reinforced Bismaleimide(BMI)/O,O'-diallyl bisphenol A(BA)/Organic Rectorite(OREC) Composites
Authors: Li Yuan  , Aijuan Gu  , Guozheng Liang  , Xiaoyan Ma  , Hongxia Yan
Published: March 2009

The three-component resin system consisting of 4,4'-bismaleimidodiphenylmethane (BMI), O,O'-diallylbisphenol A(BA) and organic rectorite (OREC) was prepared to develop a novel fiber reinforced BMI/BA/OREC composite. The effects of the content of OREC on the mechanical properties, the hot-wet resistance, the hot air aging property, and the thermal mechanical property of fiber reinforced BMI/BA/OREC composites were discussed. The morphologies of composites were characterized using a scanning electron microscope (SEM). The results indicate that the appropriate content of OREC can significantly improve the mechanical properties such as the flexural strength, the interlaminar shear strength and the modulus of flexural elasticity of fiber reinforced BMI/BA composite. The addition of OREC may enhance the hot-wet resistance and has no negative influence on the hot-air aging property of fiber reinforced BMI/BA composite. OREC may reduce the storage modulus and the glass transition temperature (Tg) of fiber reinforced BMI/BA composite.
Pharmacokinetics of Dextropropoxyphene and Nordextropropoxyphene in Elderly Hospital Patients after Single and Multiple Doses of Distalgesic. Preliminary Analysis of Results
Authors: Crome P. , Gain R. , Ghurye R. , Flanagan R.J.
Published: March 2009

1 The plasma elimination half-life of dextropropoxyphene and its metabolite nordextropropoxyphene was investigated in seven elderly hospital patients after the administration of both single and multiple doses of Distalgesic.

2 The mean elimination half-life of dextropropoxyphene after multiple dosing was 35.7 h (range 24.0-50.6 h) and the mean half-life of nordextropropoxyphene was 53.3 h (range 25.1-76.3 h).

3 The half-lives of both dextropropoxyphene and nordextropropoxyphene are much longer than those reported by other investigators in younger subjects.
Maintenance therapies for proliferative lupus nephritis: mycophenolate mofetil, azathioprine and intravenous cyclophosphamide
Authors: Contreras G , Tozman E , Nahar Nilay , Metz David
Published: March 2009

For the treatment of proliferative lupus nephritis, long-term cyclophosphamide (CY) regimens are efficacious, however, at the expense of substantial toxicity. In the last decade, sequential regimens of short-term CY induction followed by either mycophenolate mofetil (MMF) or azathioprine (AZA) maintenance have shown to be efficacious and safe reducing the long-term exposure to CY. In a maintenance study including predominantly Hispanics and African-Americans, the patients who received MMF and AZA maintenance had a higher cumulative probability of remaining free of the composite of death or chronic renal failure (CRF) compared to quarterly intravenous CY (IVCY) maintenance (89% in MMF, 80%, in AZA and 45% in IVCY). Likewise, MMF and AZA maintenance were associated with significantly lower incidence of severe infections (2% in each MMF or AZA, and 25% in IVCY), sustained amenorrhea (6% in MMF, 8% in AZA, and 32% in IVCY), and hospitalizations (one hospital-days per patient-year in each MMF or AZA, and 10 in IVCY). In a European induction study including predominantly Caucasians, patients who received any of two sequential regimens, low dose versus high dose IVCY induction both followed by AZA maintenance, had a high cumulative probability of remaining free of treatment failure (84% in low dose IVCY and 80% in high dose IVCY; treatment failure defined as a composite of free of corticosteroid resistant flare, nephrotic syndrome, doubling creatinine, and persistent elevated creatinine). Low dose IVCY and high dose IVCY induction were associated with low incidence of sustained amenorrhea (4% in each group) and severe infections (11% in low dose and 22% in high dose IVCY induction). Of interest, most of the severe infection episodes occurred while patients were receiving IVCY induction. Finally an Asian study demonstrated that patients with proliferative lupus nephritis could be effectively treated with short-term oral CY induction followed by AZA maintenance. The cumulative probability of complete remission was 76%. The relapse rate was only 11%. The incidence of permanent amenorrhea and infection were 8% and 33%, respectively. None of the Asian patients had an increase in serum creatinine level to double the baseline value. Maintenance therapies with MMF or AZA following short-term CY induction in a sequential regimen are efficacious and safe for the treatment of high-risk patients with proliferative lupus nephritis.
Mycophenolate mofetil and skin diseases
Authors: Hartmann M , Enk A
Published: March 2009

Mycophenolate mofetil (MMF) is an immunosuppressive drug the efficiency of which has been established in renal transplantation. Recent studies suggest that it may also be effective in the treatment of variant skin diseases especially if the skin lesions are triggered by lymphocytes. Studies have shown efficacy in autoimmune bullous dermatoses, atopic dermatitis and psoriasis. However, there are no placebo-controlled trials that support the use of MMF as first line therapy in these skin diseases.
Mycophenolate mofetil in patients with hepatitis C virus infection
Authors: Ramos-Casals M , Font J
Published: March 2009

Diagnosis and treatment of hepatitis C virus (HCV) -related autoimmune features has become a clinical challenge in HCV-infected patients, in whom chronic liver disease associated with severe autoimmune features may contribute to a very poor prognosis. Both antiviral and immunosuppressive therapies, either alone or in combination, seem likely to have a key role. Based on the experience of mycophenolate mofetil (MMF) use in HCV patients receiving organ transplantation, this new immunosuppressive agent might represent a safe and effective therapeutic option to treat HCV-related extrahepatic features. Recent data are available for the use of MMF in HCV patients with autoimmune manifestations, mainly for autoimmune cytopenias and vasculitic features. MMF may be used as monotherapy or in association with other drugs for cases of HCV-related autoimmune diseases refractory or intolerant to common immunosuppressive treatments, allowing the reduction of the drug dosage and avoiding serious side effects.
Reflex Seizures as Initial Manifestations of Systemic Lupus Erythematosus in Childhood
Authors: Brinciotti Mario , Ferrucci Giovanna , Trasatti Giovanni , Priori Roberta , Squilloni Elisabetta , Valesini Guido
Published: March 2009

We report a 10-year-old girl with reflex seizures characterized by visual and acoustic hallucinations, induced by visual and acoustic stimulations. The EEG showed atypical spike-wave discharges on the left temporo-occipital area, markedly activated by visual and acoustic stimuli (intermittent light, pattern-reversal stimulation and monoaural right pure tone). The patient was treated with carbamazepine and seizure stopped within 7 months. After 10 months from the start of the therapy she developed signs of systemic lupus erythematosus.
Disease Distribution of β2-Glycoprotein I-Dependent Anticardiolipin Antibodies in Rheumatic Diseases
Authors: Kaburaki Junichi , Kuwana Masataka , Yamamoto Mihoko , Kawai Shinichi , Matsuura Eiji , Ikeda Yasuo
Published: March 2009

We investigated the clinical significance of IgG β2-glycoprotein I (GPI)-dependent anticardiolipin antibodies (aCL) in rheumatic diseases. Three hundred and seventeen patients were entered. They consisted of 133 patients with SLE, 60 with RA, 45 with SSc, 37 with PM, 23 with overlap syndrome (overlap), and 19 with unclassified connective tissue disease (UCTD). IgG β2-GPI-dependent aCL were examined by ELISA. While IgG β2-GPI-dependent aCL were detected in 13% of patients with SLE, these aCL were positive in two patients with SSc, two with overlap and 14 with UCTD. A significant association between IgG β2-GPI-dependent aCL and thrombosis was found. Clinical manifestations were studied in 32 patients with secondary APS based on SLE and 14 with primary APS (PAPS). Incidences of malar rash, arthritis, renal disorder, leucopenia, immunological disorders and hypocomplementemia were significantly less frequent in patients with PAPS. IgG β2-GPI-dependent aCL were detected in all patients with PAPS and in 34% of secondary APS. This difference was significant. These data suggest that IgG β2-dependent aCL are useful for identifying a subset in patients with APS.
β2-Glycoprotein I: Target antigen for ‘antiphospholipid’ antibodies. Immunological and molecular aspects
Authors: Sheng Y , Kandiah DA , Krilis SA
Published: March 2009

It has become clear that β2-glycoprotein I (β2GPI) is the most common and best-characterised antigenic target for ‘antiphospholipid’ (aPL) autoantibodies. These antibodies preferentially bind β2GPI that has been immobilised on anionic phospholipid membranes or certain synthetic surfaces. These surfaces appear to act by increasing antigen density to allow binding of intrinsically low-affinity anti-β2GPI autoantibodies. Binding of β2GPI in fluid phase is weak and requires high concentrations of β2GPI. Our understanding of the pathophysiology of the ‘Antiphospholipid’ Syndrome (APS) has increased exponentially with the number of studies into the interactions of aPL antibodies and β2GPI.
Genetics of apolipoprotein H (β2-glycoprotein I) and anionic phospholipid binding
Authors: Kamboh MI , Mehdi H
Published: March 2009

Apolipoprotein H (apoH; also known as β2-glycoprotein I), is an essential cofactor for the binding of certain antiphospholipid antibodies (APA) to anionic phospholipid. The gene coding for apoH is polymorphic, with the occurrence of several common alleles in the general population. This genetically determined variation can effect the binding of apoH to anionic phospholipids and consequently the production of APA. Our group has identified two common mutations at codons 306 (Cys → Gly) and 316 (Trp → Ser) in the fifth domain of apoH which affect the binding of apoH to anionic phospholipids (phosphatidylserine or cardiolipin). ApoH from serum samples homozygous for each of these mutations or compound heterozygotes for both mutations showed no binding with anionic phospholipids on ELISA. In vitro mutagenesis and transient expression of these mutations in COS-1 cells followed by cardiolipin binding studies confirmed that Gly306 and Ser316 are causative mutations. Our data indicate that the fifth domain of apoH is essential for anionic phospholipid binding and genetically determined variation in this domain can affect the production of apoH-dependent APA.