bluuebunny/crossref_metadata_2025 huggingface dataset:
Augmentation of Human Thymocyte Proliferative Responses by Retinoic Acid
Authors: Sidell Neil , Famatiga Estela , Golub Sidney H.
Published: October 2008

When 10–5 to 10-7M all-trans retinoic acid (RA) was added to human thymocyte or tonsil lymphocyte cultures in the presence of mitogens or allogeneic stimulator cells, blastogenesis was increased up to 2.5-fold. No augmentation in proliferative responses of peripheral blood or spleen lymphocytes was observed. In the thymus, lymphocytes in the subclass of cells that did not bind peanut agglutinin (PNA) were responsible for the RA-induced enhancement. RA also increased the number of mitogen-stimulated thymocyte colonies developing in soft agar. These results indicate that the targets of RA activity must be lymphoid cells at a later stage of maturation than those identified by binding to PNA, and that one mechanism of RA enhancement is an increase in the number of lymphocytes that undergo blast transformation.
Membrane Surface Properties of Normal and Malignant Cells: Partition in Aqueous Two-Polymer Phase Systems
Authors: Sherbet G.V. , Lakshmi M.S.
Published: October 2008

The partition of normal and malignantly transformed fibroblast lines and cell lines initiated from malignant human astrocytomas and a benign ganglioneuroma has been examined in aqueous dextran-polyethylene glycol phase system containing phosphate buffer with a low phosphate/sodium chloride ratio. The malignant astrocytomas showed a significantly lower partition coefficient as compared with the benign ganglioneuroma. Treatment of astrocytoma cells with dexamethasone caused an increase in the partitioning of the cell population. No differences were found in the partition behaviour of normal BHK-21 cells and their malignant transformants, the TRES fibrosarcoma cells. Polyoma and simian virus-transformed 3T3 fibroblasts showed partition ratios similar to the untransformed cells. Dexamethasone pre-treatment had no effect on the partition behaviour of these cells. The significance of these observations has been discussed in relation to the surface hydrophobicity and the neoplastic state.
Activation of Sphingosine Kinase-1 Reverses the Increase in Lung Vascular Permeability Through Sphingosine-1-Phosphate Receptor Signaling in Endothelial Cells
Authors: Tauseef Mohammad , Kini Vidisha , Knezevic Nebojsa , Brannan Melissa , Ramchandaran Ram , Fyrst Henrik , Saba Julie , Vogel Stephen M. , Malik Asrar B. , Mehta Dolly
Published: October 2008

The lipid mediator sphingosine-1-phosphate (S1P), the product of sphingosine kinase (SPHK)-induced phosphorylation of sphingosine, is known to stabilize interendothelial junctions and prevent microvessel leakiness. Here, we investigated the role of SPHK1 activation in regulating the increase in pulmonary microvessel permeability induced by challenge of mice with lipopolysaccharide or thrombin ligation of protease-activating receptor (PAR)-1. Both lipopolysaccharide and thrombin increased mouse lung microvascular permeability and resulted in a delayed activation of SPHK1 that was coupled to the onset of restoration of permeability. In contrast to wild-type mice,
Sphk1
−/−
mice showed markedly enhanced pulmonary edema formation in response to lipopolysaccharide and PAR-1 activation. Using endothelial cells challenged with thrombin concentration (50 nmol/L) that elicited a transient but reversible increase in endothelial permeability, we observed that increased SPHK1 activity and decreased intracellular S1P concentration preceded the onset of barrier recovery. Thus, we tested the hypothesis that released S1P in a paracrine manner activates its receptor S1P1 to restore the endothelial barrier. Knockdown of SPHK1 decreased basal S1P production and Rac1 activity but increased basal endothelial permeability. In SPHK1-depleted cells, PAR-1 activation failed to induce Rac1 activation but augmented RhoA activation and endothelial hyperpermeability response. Knockdown of S1P1 receptor in endothelial cells also enhanced the increase in endothelial permeability following PAR-1 activation. S1P treatment of
Sphk1
−/−
lungs or SPHK1-deficient endothelial cells restored endothelial barrier function. Our results suggest the crucial role of activation of the SPHK1→S1P→S1P1 signaling pathway in response to inflammatory mediators in endothelial cells in regulating endothelial barrier homeostasis.
Activation of Histone Deacetylase 2 by Inducible Heat Shock Protein 70 in Cardiac Hypertrophy
Authors: Kee Hae Jin , Eom Gwang Hyeon , Joung Hosouk , Shin Sera , Kim Ju-Ryoung , Cho Young Kuk , Choe Nakwon , Sim Bo-Woong , Jo Daewoong , Jeong Myung Ho , Kim Kyung Keun , Seo Jeong-Sun , Kook Hyun
Published: October 2008

Diverse cardiac diseases induce cardiac hypertrophy, which leads to dilatation and heart failure. We previously reported that hypertrophy can be blocked by class I histone deacetylase (HDAC) inhibitor, which prompted us to investigate the regulatory mechanism of class I HDACs. Cardiac hypertrophy was introduced by aortic banding, by infusion of isoproterenol or angiotensin II, or by swimming. Hypertrophic stimuli transiently elevated the activity of histone deacetylase-2 (Hdac2), a class I HDAC. In cardiomyocytes, forced expression of Hdac2 simulated hypertrophy in an Akt-dependent manner, whereas enzymatically inert Hdac2 H141A failed to do so. Hypertrophic stimuli induced the expression of heat shock protein (Hsp)70. The induced Hsp70 physically associated with and activated Hdac2. Hsp70 overexpression produced a hypertrophic phenotype, which was blocked either by siHdac2 or by a dominant negative Hsp70ΔABD. In
Hsp70.1
−/−
mice, cardiac hypertrophy and Hdac2 activation were significantly blunted. Heat shock either to cardiomyocytes or to mice activated Hdac2 and induced hypertrophy. However, heat shock-induced Hdac2 activation was blunted in the cardiomyocytes isolated from
Hsp70.1
−/−
mice. These results suggest that the induction of Hsp70 in response to diverse hypertrophic stresses and the ensuing activation of HDAC2 trigger cardiac hypertrophy, emphasizing HSP70/HDAC2 as a novel mechanism regulating hypertrophy.
Aspects of Impact of Planar Deformable Bodies as Linear Complementarity Problems
Authors: Ebrahimi S. , Eberhard P.
Published: October 2008

This paper extends the linear complementarity problem formulation of [7] and [8] for normal impact of planar deformable bodies in multibody systems. In the kinematics of impact we consider the normal gaps between the impacting bodies in terms of the generalized coordinates. Then, the generalized coordinate’s vector is formulated in terms of the impact forces using the 5th order implicit Runge‐Kutta approach RADAU5. Substituting the generalized coordinates in the relation of normal gaps together with the complementarity relations of unilateral contact constraints leads to a linear complementarity problem where its solution results in the solution of the impact problem including impact forces and normal gaps. Then, alternatively another formulation on velocity level based on the 4th order explicit Runge‐Kutta is presented. In the presented approach no coefficient of restitution is used for treatment of energy loss during impact and, instead, the material damping is responsible for energy loss. A good agreement between the results of our approach with the results of FEM for soft planar deformable bodies was shown in [7]. Here, we improve the results for stiff planar deformable bodies and show that with a proper selection of eigenmodes, the results on both position and velocity level approach the precise results of FEM provided that an optimal time step of the integration is chosen. We also investigate the effect of considering material damping and some higher eigenfrequencies on the amount of energy which is dissipated during impact based on our approach.
Ethnic Diversity and Generalized Trust in Europe
Authors: Hooghe Marc , Reeskens Tim , Stolle Dietlind , Trappers Ann
Published: October 2008

While most current research documents a negative relation between ethnic diversity and generalized trust, it has to be acknowledged that these results often originate from one-country analyses in North America. In this article, attitudinal measurements from the European Social Survey are combined with Organization for Economic Co-Operation and Development data on migration patterns, thus examining the relationship between diversity and trust in a comparative manner across 20 European countries. More fine-grained measurements of diversity (including type and rise of diversity over time and legal status of immigrants) are included in a multilevel model. At the individual level, most of the familiar relations were confirmed. At the country level, hardly any indicators for migration or diversity proved to be strongly and consistently related to generalized trust. Results suggest that the pessimistic conclusions about the negative effects of ethnic diversity on generalized trust cannot be confirmed at the aggregate level across European countries.
The Age Discrimination in Employment Act and the Challenge of Population Aging
Authors: Neumark David
Published: October 2008

The author reviews evidence on age discrimination in U.S. labor markets and on the effects of the Age Discrimination in Employment Act (ADEA) in combating this discrimination, focusing on the challenge of population aging facing the U.S. economy in coming decades. Combating age discrimination is likely to help in meeting this challenge by encouraging the employment of older individuals. But the author also explores how the rapid aging of the population protected by the ADEA might inhibit the ADEA's effectiveness and raises questions about possible changes in age discrimination policies and enforcement that could enhance the ability of the ADEA to mitigate some of the adverse consequences of population aging.
Labor-Force Dynamics at Older Ages
Authors: Zissimopoulos Julie M. , Karoly Lynn A.
Published: October 2008

Labor-market transitions toward the latter parts of workers' careers can be complex, with movement between jobs and classes of work and in and out of retirement. The authors analyzed factors associated with the labor-market transitions of older workers to self-employment from unemployment or disability, retirement, or wage and salary work using rich panel data from seven waves of the Health and Retirement Study (HRS). They found evidence that (prior) job characteristics and liquidity constraints are important predictors of movements to self-employment for workers and nonworkers, while risk aversion is a significant predictor only for workers.
Intertemporal Tradeoffs: Perceiving the Risk in the Benefits of Marijuana in a Prospective Study of Adolescents and Young Adults
Authors: Goldberg Julie H. , Millstein Susan , Schwartz Alan , Halpern-Felsher Bonnie
Published: October 2008

Purpose . Intertemporal tradeoffs characterize the decision to use drugs: pleasure now traded off against the possibility of pain later. Traditional approaches have examined whether individuals use drugs because they either seek immediate benefit or fail to appreciate long-term risk. We asked whether risk taking might also result from failing to appreciate benefits. We refer to this as risk in the benefits (RIBs), an understanding that one's first drug experience can be so good , that a person may not want (or be able) to stop, putting him/her on a path that leads directly to addiction. Methods . In total, 304 participants, 160 adolescents and 144 young adults, participated in a longitudinal study on marijuana use and other risky health behaviors. Results . The failure to perceive the RIBs of marijuana use led to increased risk taking 1 year later within 3 different health behaviors: alcohol, tobacco, and sexual risk-taking. Greater appreciation of RIBs predicted significantly less future risk taking over-and-above all the traditional cognitive and behavioral predictors, and RIBs were the only significant cognitive predictor when all were included in 1 model. RIBs also partially mediated the relationship between past and future risk taking, over and above the strongest predictors of risk taking. Conclusions . Failing to appreciate the impact of short-term benefits within the context of long-term risk increased future risk taking. Interventions that enhance the salience of RIBs may represent a new approach to reducing the likelihood that individuals will take risks with their health.
The Use and Abuse of Painkillers in International Soccer
Authors: Tscholl Philippe , Feddermann Nina , Junge Astrid , Dvorak Jiri
Published: October 2008

Background

It is known that in professional men's soccer the consumption of prescription medication is high.

Purpose

The intake of medication in female and adolescent male soccer players has not yet been investigated.

Study Design

Descriptive epidemiology study.

Material

Team physicians reported 10 456 uses of medication 72 hours before each match in 2488 soccer players participating in 6 international soccer tournaments.

Results

The use of a total of 6577 medical substances was reported, leading to an average intake of 0.63 substances per player per match (under-17s, 0.51; under-20s, 0.51; women, 1.0; P ≤. 001 [without contraceptive medication, 0.85; P <. 001]). Nonsteroidal anti-inflammatory drugs were the most commonly prescribed type of medication in all tournaments. Women's soccer had the highest percentage of players using nonsteroidal anti-inflammatory drugs per match (under-17s, 17.3%; under-20s, 21.4%; women, 30.7%; P ≤. 001). Relatively few players were taking β2-agonists for the treatment of asthma (under-17s, 1.3%; under-20s, 1.3%; women, 4.3%; P ≤. 001).

Conclusion

These findings highlight the existing problem of excessive medication use in international top-level women's and male youth soccer nearly to the same extent as in men's soccer. Further steps need to be taken to understand the rationale underlying the sports physicians’ practice and to plan educational programs to avoid the abuse of prescription medication.

Clinical Relevance

Continued abuse of medication may otherwise not only negatively influence the quality of the game but also the health status of the players.
Reading Success
Authors: Idol Lorna
Published: October 2008

Reading Success is an individualized teacher-guided literacy program proven for 663 students who experienced difficulty with reading. The students had learning disabilities, mild mental retardation, and behavior challenges; were at risk for school failure; or were transitioning from speaking Spanish to English and experiencing literacy problems. Pupil progress data, as measured by progress over time in various reading curricula, reflected student gains of a half year to more than 3 years per year of instruction. Monthly curricular progress data ranged from 0.03 to 6.80 months’ gain per month of instruction. Many students showed equivalent gains on standardized informal reading inventories, with some passing a statewide test for the first time. Thirty-five special education students returned to regular education programs. All students received the basic lesson, reflecting reading research-based practices. Some students received specialized interventions that focused on three critical reading behaviors (word reading accuracy, reading speed, reading comprehension) and written language (composition, mechanical skills).
The Learning Way
Authors: Kolb Alice Y. , Kolb David A.
Published: October 2008

Contemporary research on meta-cognition has reintroduced conscious experience into psychological research on learning and stimulated a fresh look at classical experiential learning scholars who gave experience a central role in the learning process—William James, John Dewey, Kurt Lewin, Carl Rogers, and Paulo Freire. In particular James's contributions are foundational for experiential learning and research on meta-cognition. Research on meta-cognition and the role it plays in the learning process are described. The meta-cognitive model is used to describe how fundamental concepts of experiential learning theory—a learning self-identity, the learning spiral, learning style, and learning spaces—can guide meta-cognitive monitoring and control of learning. Meta-cognitive strategies to help individuals improve their learning effectiveness are outlined. Learners can chart their path on the learning way by developing their meta-cognitive learning capacities, and educators can pave the way by placing learning about learning on the agenda of their educational programs.
The Development of Franchise Operations in Emerging Markets
Authors: Klonowski Darek , Power Jacqueline L. , Linton Daniel
Published: October 2008

For entrepreneurs in the emerging markets of Central and Eastern Europe, franchising presents an opportunity to develop a start-up business with the assistance of an international firm. However, emerging markets are demanding environments for establishing and operating a business. These environments challenge the ability of franchisors to transfer their franchise concept from their home market to the emerging market. This case focuses on the evolution of “American Restaurant Format” (ARF), one of the few franchise restaurant operators in Central and Eastern Europe. Notwithstanding the challenges of the Polish market, the case shows that most of ARF's problems were self-inflicted, the result of poor judgment and an inflexible franchise organization.
Fabrication of SiC particle reinforced composite on aluminium surface by friction stir processing
Authors: Mahmoud E. R. I. , Ikeuchi K. , Takahashi M.
Published: October 2008

A feasibility investigation has been carried out of the formation of surface composite by uniformly distributing SiC particles 1˙25 µm in size into a surface layer of an A 1050-H24 Al plate through friction stir processing (FSP). The SiC particle was filled into a groove cut on the Al plate, covered by an Al sheet 2 mm thick, and a rotating tool was penetrated from the cover sheet so that the probe tip reached a depth beyond the groove bottom. The effects of process parameters (rotation speed and travelling speed) and applying multiple passes on the distribution of SiC particle in the nugget zone were investigated. The effects of groove size and its position relative to the tool probe were also investigated. Applying multiple passes had a great effect on the homogeneity of the SiC particle distribution. At rotation speeds of 2000–3000 rev min−1, the SiC particles tended to cluster in some places in the nugget zone. By decreasing the rotation speed to 1000–1500 rev min−1, the SiC particle was distributed in almost all the nugget zone area when the groove was 2–3 mm wide and 1˙5 mm deep. On the other hand, the stirring action of FSP was insufficient to distribute homogenously the SiC particles when the groove size was increased to 3×2 mm. By shifting the groove position towards the advancing side of the tool probe, the distribution of the SiC particles in the nugget zone became better. The defect free nugget zone with homogenously distributed SiC particles was obtained in a sample produced by FSP at rotation speeds of 1500 rev min−1 for the first pass and 1250 rev min−1 for the second and third passes. Microhardness of the nugget zone was increased to a level as high as 55 HV when the groove size was 3×1˙5 mm. The effect of the rotation speed on the particles dispersion was discussed with particular reference to the vertical material flow in the nugget zone.
Application of electrode force change in single sided resistance spot welding using servo gun
Authors: Li Y. B. , Liang C. P. , Zhang Y. S. , Lin Z. Q.
Published: October 2008

Single sided resistance spot welding (SSRSW) is considered as a feasible method to join hydroformed or closed section parts to others in vehicle productions. Unfortunately, it is difficult to guarantee the weld quality utilising conventional air gun. Because of a lack of support inside the closed section parts, the impact of electrode driven by pneumatic gun will cause large deformation of the workpieces at the welding stage and will lead to a crack around weld region after welding completion. In addition, poor weldability is another pressing problem for welding operations. Servo gun with new gun driven method has some merits such as realising the soft touch between electrode and workpieces and changing electrode force during the welding process which are greatly suitable to the sheet to tube joining. Based on the characteristics of servo gun, the present paper investigates a new method to increase the weld quality of sheet to tube joining with SSRSW method. By adjusting the electrode force during the welding process, weld strength would be increased, weld deformation be decreased and weldability lobe curve be widened. The results verify that servo guns can provide high assurance for welding quality of sheet to tube joining and have broad prospect in SSRSW.
Coalesced bainite by isothermal transformation of reheated weld metal
Authors: Pak J. H. , Bhadeshia H. K. D. H. , Karlsson L. , Keehan E.
Published: October 2008

The martensite start and bainite start temperatures have been determined in reheated, high strength weld deposits, with each result associated with 95% coincidence limits. This helped define isothermal transformation temperatures where bainite can be obtained without the risk of unintentional transformation to martensite. It has been demonstrated, therefore, that coalesced bainite, which is detrimental to mechanical properties, can be generated isothermally without the possibility of confusion with autotempered martensite.
Microstructural analysis of stir zone of Al alloy produced by friction stir spot welding
Authors: Fujimoto M. , Koga S. , Abe N. , Sato Y. S. , Kokawa H.
Published: October 2008

Friction stir spot welding (FSSW), which was recently developed as a spot joining technique, has been applied to a lap joint of Al alloy 6061 sheets, 1 mm in thickness, to clarify its microstructural features of the joint. A nugget shaped stir zone having finer grain size was observed around the exit hole of the probe. Crystallographic texture analyses using EBSD method suggested that the material flow occurred along the rotating direction of the FSSW tool in the wide region including the stir zone. In the periphery of the nugget shaped stir zone, which was characterised by finer grain size than the stir zone interior, no inclusions or precipitates were found on the SEM scale. A softened region was formed around the joint centre, which could be explained as resulting from dissolution and/or growth of the strengthening precipitates due to thermal cycle of FSSW.
Experimental study of joint performance in spot friction welding of 6111-T4 aluminium alloy
Authors: Arul S. G. , Miller S. F. , Kruger G. H. , Pan T.-Y. , Mallick P. K. , Shih A. J.
Published: October 2008

The effect of process parameters (cycle time, tool speed and axial force) on the specimen temperature measured 2 mm away from the weld in spot friction welding (SFW) of Al 6111-T4 is investigated. The temperatures were correlated to the lap shear load. Results revealed that, to achieve a good joint strength with the maximum lap shear load >2˙5 kN, temperatures should be greater than a threshold value, which is 350°C at a location close to the SFW joint in this study. By studying the specimen macrographs, two internal weld geometric features based on the cross-section area were identified and correlated to the shear and mixed failure modes of the lap shear tested specimens. A model was developed and validated using experimental data of the cross section area of SFW joint with either shear or mixed mode fracture. The model predicts that the SFW joint strength is maximised at the transition region between the shear and mixed mode fracture.
Tensile behaviour of different pretreated alloy 718 sheets welded with electron beam welding (EBW)
Authors: Huang C. A. , Wang T. H. , Chang Y. Z. , Han W. C. , Lee C. H.
Published: October 2008

The present paper investigates the tensile behaviour of alloy 718 sheets processed after electron beam welding (EBW). The alloy 718 sheets were pretreated in three conditions: as received, solution and precipitation pretreatments. Metallographic and fractographic examination on the specimens were conducted with optical microscope, scanning and transmission electron microscopes. Experimental results show that cracks propagate through all of the fusion zones during tensile test. The intermetallic laves phase, which precipitates along the fine columnar grain boundary in the fusion zone, offers a preferred crack propagation path, especially for the precipitation pretreated weld. The static ductility of precipitation-treated weld decreases significantly after EBW. This was attributed to high precipitation density of laves phase along the columnar grain boundary. Relatively high tensile strength and ductility of as-received and solution-pretreated welds can be obtained by using two sequential welding passes. The first pass is full penetration welding with high heat input, and the secondary pass uses cosmetic welding to reduce the surface undercut resulted from the first pass.
Neurowavelet packet analysis based on current signature for weld joint strength prediction in pulsed metal inert gas welding process
Authors: Pal S. , Pal S. K. , Samantaray A. K.
Published: October 2008

The monitoring of welding process is crucial for the development of a real time quality control system for the pulsed metal inert gas welding (PMIGW) process. This work introduces an intelligent system for weld joint strength prediction in a PMIGW process based on the analysis of acquired current signal by wavelet packet transform. A thirteen-dimensional array of process features, i.e. six process parameters and seven wavelet packet features, are used to describe various welding conditions. These process features obtained from a set of experiments are employed as input vectors of an artificial neural network model to predict the corresponding weld joint strengths. The results, i.e. the prediction errors, show that the use of wavelet packet features gives much accurate prediction as compared to the use of the purely time domain features.
Effects of base and filler chemistry and weld techniques on equiaxed zone formation in Al–Zn–Mg alloy welds
Authors: Dev S. , Murty B. S. , Rao K. P.
Published: October 2008

Equiaxed zone (EQZ) formation in Al–Zn–Mg alloy welds as affected by base metal, filler metal chemistry and weld techniques is studied. Filler metal chemistry and welding techniques have great influence on the formation of EQZ microstructure as base metal composition has. In an effort to characterise the equiaxed grain zone formation in Al–Zn–Mg alloy welds two commercial Al alloys AA7018 and RDE40 were selected. Gas tungsten arc welding in continuous current, pulsed current and arc oscillation mode were applied to weld the base materials. The influence of Sc containing fillers have been studied and compared with the commercial filler material. Mechanical and metallurgical characterisation were carried out in the EQZ. Intergranular corrosion in EQZ was studied according to ASTM G 110-92. Results reveals that RDE40 with low solute contents showed wider EQZ but relatively better corrosion and mechanical properties compared to AA7018 EQZ. Gas tungsten arc welding in pulsed and arc oscillation mode fusion boundary region exhibits better corrosion and mechanical properties compared to continuous current mode welds. Addition of Sc to the AA5556 filler combined with pulsed mode resulted in elimination of EQZ, better corrosion and mechanical properties compared to welds made with conventional AA5556 filler and also the presence of Sc within the EQZ so called unmixed zone has been observed.
Role of electroplated interlayer in continuous drive friction welding of AA6061 to AISI 304 dissimilar metals
Authors: Reddy Madhusudhan G. , Rao Sambasiva A. , Mohandas T.
Published: October 2008

Aluminium austenitic stainless steel joints find application in cryogenic engines, spacecrafts and automobiles. This dissimilar material combination is unweldable by conventional fusion welding due to a tendency for brittle intermetallic formation. Solid state welding processes such as friction welding are reported to be employed in such situations. This paper deals with continuous drive friction welding of AA6061 Al alloy to AISI 304 austenitic stainless steel. Direct welding of this combination resulted in brittle joints with 0° bend angle due to the formation of Fe2Al5. To alleviate this problem welding was carried out by incorporating Cu, Ni and Ag as diffusion barrier interlayers. The interlayer was incorporated by electroplating. Welds with Cu and Ni interlayer were also brittle due to the presence of CuAl2 and NiAl3. Ag acted as an effective diffusion barrier for Fe avoiding the formation of Fe2Al5. Therefore welds with Ag interlayer were stronger and ductile and could be bent to an angle of 100°.
Cracking in dissimilar Mg alloy friction stir spot welds
Authors: Yamamoto M. , Gerlich A. , North T. H. , Shinozaki K.
Published: October 2008

Cracking during dissimilar friction stir spot welding of thixomoulded AM60 and AZ91 sheet materials is investigated. Liquation cracking occurs in the thermomechanically affected zone (TMAZ) region during friction stir spot welding when AZ91 material is the lower sheet in the dissimilar AM60/AZ91 sandwich. A TMAZ microstructure comprising elongated α-Mg grains and aligned Mg17Al12 is created during the tool penetration stage in spot welding and melted eutectic film formation is facilitated since the temperature in the stir zone (504°C) is much higher than the α-Mg+Mg17Al12 eutectic temperature (437°C).

There is no evidence of liquation cracking in the stir zone or the TMAZ region of AM60 sheet when it is the lower sheet in the dissimilar sandwich. However, liquation cracking is observed in the upper sheet material (AZ91) in the location beneath the tool shoulder close to its periphery.
Influence of cooling rate and composition on orientation of primary carbides of Fe–Cr–C hardfacing alloys
Authors: Wang Z. H. , Wang Q. B. , Cui L. , Yang A. D. , He D. Y.
Published: October 2008

Four Fe–Cr–C hardfacing alloys with carbon contents of 3˙34–6˙5% were studied. The orientation of primary carbides in the microstructures of hardfacing layers produced by arc surfacing was investigated under controlled cooling conditions. Carbon content and cooling conditions were found to play an important role in determining overlayer microstructures. Increasing carbon content or decreasing Cr/C ratio increased the tendency for primary carbides to be oriented perpendicular to the surface of the overlayers, and the carbides in the microstructure became more compact. Under water cooling conditions, the primary carbides were preferentially oriented perpendicular to the surface, which would be expected to improve wear resistance. At lower cooling rates, primary carbides were oriented randomly.
AT-101 induces apoptosis in CLL B cells and overcomes stromal cell–mediated Mcl-1 induction and drug resistance
Authors: Balakrishnan Kumudha , Burger Jan A. , Wierda William G. , Gandhi Varsha
Published: October 2008

Resistance to apoptosis in CLL B cells is associated with overexpression of Bcl-2 family antiapoptotic proteins. Their expression is endogenous, but is also induced by signals from the microenvironment resulting in intrinsic and extrinsic drug resistance. Because AT-101 binds to the BH3 motif of all Bcl-2–family antiapoptotic proteins, we hypothesized that this molecule could overcome resistance. AT-101 treatment (20 μM for 24 hours) resulted in a median 72% apoptosis in CLL cells (patients; n = 32, P < .001). Stromal cells protected CLL B cells from spontaneous and fludarabine-induced apoptosis (P = .003) by increasing the Mcl-1 protein levels. However, AT-101 induced similar extent of down-regulation of Mcl-1 and apoptosis in CLL lymphocytes cultured in suspension or on stroma (P = .999). Stromal cells expressed undetectable levels of antiapoptotic but high levels of activated ERK and AKT proteins and had low or no apoptosis with AT-101. Collectively, these data demonstrate that AT-101 induces apoptosis in CLL B cells and overcomes microenvironment-mediated resistance while sparing normal stromal cells.
Toll-like receptor homolog RP105 modulates the antigen-presenting cell function and regulates the development of collagen-induced arthritis
Authors: Tada Yoshifumi , Koarada Syuichi , Morito Fumitaka , Mitamura Mio , Inoue Hisako , Suematsu Rie , Ohta Akihide , Miyake Kensuke , Nagasawa Kohei
Published: October 2008

Introduction

RP105 is a Toll-like receptor homolog expressed on B cells, dendritic cells (DCs), and macrophages. We investigated the role of RP105 in the development of collagen-induced arthritis (CIA).

Methods

CIA was induced in RP105-deficient DBA/1 mice and the incidence and arthritis index were analyzed. The cytokine production by spleen cells was determined. The functions of the DCs and regulatory T cells (Tregs) from RP105-deficient or control mice were determined by adding these cells to the lymph node cell culture. Arthritis was also induced by incomplete Freund's adjuvant (IFA) plus collagen or by injecting anti-collagen antibody and lipopolysaccharide.

Results

RP105-deficient mice showed accelerated onset of arthritis and increased severity. Interferon-gamma (IFN-γ) and tumor necrosis factor-alpha production by spleen cells from RP105-deficient mice was increased in comparison with that from wild-type mice. The DCs from RP105-deficient mice induced more IFN-γ production, whereas Tregs from those mice showed less inhibitory effect against IFN-γ production. RP105-deficient mice also showed more severe arthritis induced by collagen with IFA.

Conclusions

These results indicate that RP105 regulates the antigen-presenting cell function and Treg development, which induced the attenuation of the cell-mediated immune responses and, as a result, suppressed the development of CIA.
Substance P (SP) enhances CCL5-induced chemotaxis and intracellular signaling in human monocytes, which express the truncated neurokinin-1 receptor (NK1R)
Authors: Chernova Irene , Lai Jian-Ping , Li Haiying , Schwartz Lynnae , Tuluc Florin , Korchak Helen M , Douglas Steven D , Kilpatrick Laurie E
Published: October 2008

Substance P (SP) is a potent modulator of monocyte/macrophage function. The SP-preferring receptor neurokinin-1 receptor (NK1R) has two forms: a full-length NK1R (NK1R-F) isoform and a truncated NK1R (NK1R-T) isoform, which lacks the terminal cytoplasmic 96-aa residues. The distribution of these receptor isoforms in human monocytes is not known. We previously identified an interaction among SP, NK1R, and HIV viral strains that use the chemokine receptor CCR5 as a coreceptor, suggesting crosstalk between NK1R and CCR5. The purpose of this study was to determine which form(s) of NK1R are expressed in human peripheral blood monocytes and to determine whether SP affects proinflammatory cellular responses mediated through the CCR5 receptor. Human peripheral blood monocytes were found to express NK1R-T but not NK1R-F. SP interactions with NK1R-T did not mobilize calcium (Ca2+), but SP mobilized Ca2+ when the NK1R-F was transfected into monocytes. However, the NK1R-T was functional in monocytes, as SP enhanced the CCR5 ligand CCL5-elicited Ca2+ mobilization, a response inhibited by the NK1R antagonist aprepitant. SP interactions with the NK1R-T also enhanced CCL5-mediated chemotaxis, which was ERK1/2-dependent. NK1R-T selectively activated ERK2 but increased ERK1 and ERK2 activation by CCL5. Activation of NK1R-T elicited serine phosphorylation of CCR5, indicating that crosstalk between CCL5 and SP may occur at the level of the receptor. Thus, NK1R-T is functional in human monocytes and activates select signaling pathways, and the NK1R-T-mediated enhancement of CCL5 responses does not require the NK1R terminal cytoplasmic domain.
Concentration of Anions by Silica Adsorbents with Immobilized Nitrogen-Containing Polymers
Authors: Tertykh V.A. , Polishchuk L.M. , Yanovska E.S. , Dadashev A.D.
Published: October 2008

Immobilization of a polyionene complex on a silica gel surface immediately after polymer formation ( in situ immobilization) and the covalent anchorage of polyhexamethylene guanidine hydrochloride onto an amino-containing silica surface have been performed. The adsorption properties of the modified silica adsorbents with respect to Cr(IV), Mo(VI), W(VI), As(V), P(V) and V(V) anions were studied. Silica gels with chemically-bound polyhexamethylene guanidine hydrochloride effected the quantitative removal of V(V), W(VI), Mo(VI) and As(V) anions from their acidic (pH = 2–4) and neutral solutions, although their kinetic characteristics were closer to those of polymeric sorbents. Silicas with in situ immobilized polyionene complexes quantitatively extracted As(V), W(VI) and Mo(VI) anions, and exhibited a high adsorption activity towards Cr(IV), P(V) and V(V) anions from acidic (pH = 1–4) media with adsorption equilibrium being attained at a high rate. The adsorbents synthesized exhibited high adsorption capacities towards the anions investigated.
Determination of Hansen Solubility Parameters by Means of Gas-Solid Inverse Gas Chromatography
Authors: Voelkel Adam , Batko Kalina , Adamska Katarzyna , Strzemiecka Beata
Published: October 2008

The determination of Hansen Solubility Parameters (HSP) from inverse gas chromatographic (IGC) data for a group of nano-materials and modified nano-materials is presented and discussed.

The solubility parameter concept is applied in many industries to explain the different properties of the various components in a formulation. Knowledge of the solubility parameter data for different components is important for predicting the magnitude of the interaction between the formulation components and the future stability of the product. Solubility parameter data are also useful in the description and interpretation of different phenomena occurring between materials such as their miscibility, compatibility or adsorption.

The inverse gas chromatography method is widely used for the characterization of polymers and polymer blends, surfactants, biopolymers, solid food and petroleum pitches. The method involves placing the investigated material (stationary phase) in a column and then characterizing it using volatile probes with known properties (test solutes) which are carried by a mobile phase.

The solubility parameter called the Hildebrand solubility parameter or the Hildebrand parameter is only applied for regular solutions. The so-called Hansen solubility parameter (HSP) is an extension of the Hildebrand solubility parameter to polar and hydrogen-bonding systems. Hansen assumed that the cohesive energy can be considered as the sum of the contributions from dispersive (Ed), polar (Ep) and hydrogen-bonding (Eh) interactions: –Ecoh = –Ed – Ep – Eh; and that the total solubility parameter (δT) may be expressed as δT2 = δd2 + δp2 + δ2h, where δp, δp and δh denote the dispersive, polar and hydrogen-bonding contribution, respectively.

The estimation of HSP from IGC data for a group of nano-materials and modified nano-materials is presented and discussed here.
Investigation of the Effect of Temperature on the Structure of the Polyacrylic Acid Adsorption Layer at a Controlled Porosity Glass/Polymer Solution Interface
Authors: Wiśniewska Malgorzata
Published: October 2008

The influence of temperature on the structure of polyacrylic acid (PAA) adsorption layers on the surface of controlled porosity glass (CPG) was studied. For this purpose, adsorption, surface charge, zeta potential and viscosity measurements were carried out over the 15–35°C temperature range. The amounts of adsorbed polymer and the thickness of the polymer adsorption layer increase with increasing temperature. This is caused by conformational changes in the polymer macromolecules with increasing temperature, changing from a coiled structure at lower temperature to a more stretched structure at higher temperature. The free energies of the PAA segments adsorbed onto the CPG surface at 25°C were calculated from the adsorption data. Decreases in the charges on the surface and diffuse layers of CPG particles were observed in the presence of PAA. On the basis on these data, proposals have been made regarding the main factors causing the changes in the zeta potential and surface charge of CPG in the presence of polymer.
Adsorption–Desorption Cycles for the Separation of Vapour-Phase Ethanol/Water Mixtures
Authors: Kupiec Krzysztof , Rakoczy Jan , Zieliński Lukasz , Georgiou Andreas
Published: October 2008

A theoretical analysis and the results of the experimental verification of the adsorption–desorption process for ethanol dehydration are presented. This adsorption–desorption process is applied in industrial installations for the production of dehydrated ethanol as a fuel additive.

In the present work, the experiments were performed using a small-scale experimental setup. The sequence of operations consisted of adsorption, vacuum desorption and purge. The adsorption column, filled with zeolite 3A pellets, was fed with a vapour-phase ethanol/water mixture containing 25 mol% water. The water vapour content at the column outlet was determined using gas chromatography. During the vacuum desorption step, the upper outlet of the column was connected to a vacuum pump. During the purge step, the lower outlet of the column was connected to a vessel containing pure ethanol while the upper outlet was connected to the vacuum pump.

The process simulation results using the developed model have been compared with the experimental results in order to verify accuracy of the model. The agreement between the experimental and theoretical results demonstrated that the mathematical model adequately described the process.
Adsorption and Movement of Endosulfan in Soils: A Verification of the Co-Solvent Theory and a Comparison of Batch Equilibrium and Soil Thin Layer Chromatography Results
Authors: Singh R.P. , Singh Sujata
Published: October 2008

Batch equilibrium and soil thin-layer chromatography (soil TLC) techniques were used to investigate the influence of different volume fractions (fs = 0.25, 0.50, 0.75 and 1.0) of organic co-solvents (acetone and methanol) on the adsorption and movement of endosulfan in three different types of Indian soils (silt loam, loam and sandy loam).

The measured equilibrium adsorption isotherms for all three soils studied were L-shaped for both co-solvent/water mixtures at all fs values. All isotherms were in close agreement with the Freundlich equation. Higher adsorption of endosulfan was observed on silt loam soil followed by loam and sandy loam soils at all fs values for both co-solvent systems, as was anticipated from the values of the Freundlich constants, K, and the partition coefficients, KD. The order of the K and KD values also confirmed that endosulfan adsorption was higher in methanol/water mixtures than in acetone/water mixtures and decreased with increasing fs values.

The Rf values obtained from soil TLC studies were inversely proportional to the K and KD values for both co-solvent systems. The higher K and KD values and lower Rf values in methanol/water mixtures relative to acetone/water mixtures for all the three soils studied indicated that acetone had a greater potential for ground water contamination through leaching from potential sites than methanol. The affinity of endosulfan towards the organic carbon and clay content of the soils was evaluated by calculating the KOC and KC values. The data obtained indicated that, although the affinity of endosulfan was better correlated with the organic carbon content, the contribution of the clay content of soils towards endosulfan adsorption cannot be ignored. The adsorption data were used to evaluate the co-solvent theory for describing the adsorption of endosulfan in acetone/water and methanol/water mixtures. The aqueous-phase partition coefficients, KDW (mol/g), normalized with respect to foc for endosulfan were evaluated via the extrapolation fs → 0.
Design of Reactive Muffler for Study on the Noise Level and Performance of a Two Cylinder Four Stroke 16 h.p Diesel Engine
Authors: Bhattacharya Paritosh , Panua Rajsekhar , Bose Prabir Kumar , Ghosh Bankim Bihari
Published: October 2008

Exhaust noise from internal combustion engine is most harmful. However this noise can be reduced sufficiently by means of a well designed muffler. Suitable design and development will help to reduce the noise level, but at the same time the performance of the engine should not be hampered by the back pressure caused by the muffler.

The authors designed and fabricated a reactive muffler and afterward compared the noise level, Brake thermal efficiency and Brake Specific Fuel Consumptions with the existing muffler and the modified designed and fabricated muffler.
Casting the Net: A Multimodal Network Perspective on User-System Interactions
Authors: Kane Gerald C. , Alavi Maryam
Published: October 2008

Information systems (IS) researchers have typically examined the user-system relationship as an isolated dyad between a single, independent user and an individual, freestanding information system. We argue that this conceptualization does not adequately represent most organizations today, in which multiple users interact with multiple information systems within a group. Relying heavily on the theory and methods behind social network analysis, we introduce the concept of multimodal networks to assess both users and information systems as equivalent nodes in a single social network. This perspective allows us to examine the influence of information systems on organizational outcomes as a function of all of the user-system and interpersonal interactions in a group. We explore two different possible mechanisms for this influence: (1) direct user-system interactions by aggregating the strength of all the dyadic user-system interactions in a group, and (2) indirect user-system interactions by assessing the centrality of the information systems within the social network. We survey approximately 600 individuals in 40 healthcare groups to test whether either or both of these mechanisms are associated with two types of organizational performance outcomes—efficiency and quality of care. We find that the centrality of the information systems within the network is significantly and positively associated with both efficiency and quality outcomes, but that the average strength of the user-system interactions is not. Implications are that managers and researchers should examine the wider multimodal network of multiple users and multiple systems when assessing the role of IS in organizations in relation to organizational performance outcomes.
Social Capital and Knowledge Integration in Digitally Enabled Teams
Authors: Robert Lionel P. , Dennis Alan R. , Ahuja Manju K.
Published: October 2008

To understand the impact of social capital on knowledge integration and performance within digitally enabled teams, we studied 46 teams who had a history and a future working together. All three dimensions of their social capital (structural, relational, and cognitive) were measured prior to the team performing two tasks in a controlled setting, one face-to-face and the other through a lean digital network. Structural and cognitive capital were more important to knowledge integration when teams communicated through lean digital networks than when they communicated face-to-face; relational capital directly impacted knowledge integration equally, regardless of the communication media used by the team. Knowledge integration, in turn, impacted team decision quality, suggesting that social capital influences team performance in part by increasing a team's ability to integrate knowledge. These results suggest that team history may be necessary but not sufficient for teams to overcome the problems with the use of lean digital networks as a communication environment. However, team history may present a window of opportunity for social capital to develop, which in turn allows teams to perform just as well as in either communication environment.