bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fibronectin and culture temperature modulate the efficacy of an avidin–biotin binding system for chondrocyte adhesion and growth on biodegradable polymers
Authors: Tsai Wei‐Bor , Wang Peng‐Yuan , Chang Yung , Wang Min‐Cheng 
Published: March 2007

AbstractCell adhesion to a scaffold is a prerequisite for tissue engineering. Many studies have been focused on enhancing cell adhesion to synthetic materials that are used for scaffold fabrication. Previously, we showed that immobilization of biotin molecules to chondrocyte surfaces enhanced cell adhesion to avidin‐coated biodegradable polymers such as poly‐L‐lactic acid, poly‐D,L‐lactic acid and polycaprolactone. However, the endocytosis of cell membrane biotin molecules decreases binding strength between biotinylated‐chondrocytes (B‐chondrocytes) and avidin‐coated substrata, and therefore decreases cell spreading and discourages long‐term chondrocytes culture. In this study, we proposed two strategies to solve the shortcoming of the avidin–biotin binding system. First, the avidin–biotin binding system is combined with the intrinsic integrin‐dependent adhesion systems in order to enhance long‐term cell culture. Second, the incubation temperature is lowered in order to slow down the endocytosis process. We found that the avidin–biotin binding system in combination with FN–integrin binding system enhanced cell adhesion, cell spreading and cell growth. Decrease of cell culture temperature to 4°C enhanced the adhesion of B‐chondrocytes to the avidin‐coated surfaces, but decreased cell viability and proliferation, compared to culture temperature of 37°C. Whether there is an optimal seeding temperature between 4 and 37°C for both adhesion and proliferation of B‐chondrocytes needs further investigation. Our results indicated that modulation of the adhesion conditions could further enhance the efficacy of the avidin–biotin binding system in mediating cell adhesion, and subsequent tissue culture. Biotechnol. Bioeng. 2007;98; 498–507. © 2007 Wiley Periodicals, Inc.
Gas‐chromatographic approach to probe the absence of molecular inclusion in enantioseparations by carbohydrates. Investigation of linear dextrins (“acyclodextrins”) as novel chiral stationary phases
Authors: Sicoli Giuseppe , Pertici Francesca , Jiang Zhengjin , Jicsinszky Lazslo , Schurig Volker 
Published: March 2007

AbstractAcetylated/silylated maltooligosaccharides with different degrees of oligomerization have been tested as chiral stationary phases for enantioselective gas chromatography. The acyclic dextrin derivatives carrying tert‐butyldimethylsilyl groups at the primary hydroxyl sites and acetyl groups at the secondary hydroxyl sites showed an unexpected ability for the enantioseparation of α‐amino acid derivatives and halogenated compounds, in addition to some underivatized chiral compounds. Some examples of an improved enantioselectivity invoked by the linear CSPs as compared to that of cyclic oligosaccharides are demonstrated in this work. The results highlight the role of the polar external surface of the selector in lieu of the well‐established inclusion mechanism of enantiorecognition by cyclic dextrins. Thus, the enantioseparation of chiral compounds on linear dextrin derivatives—devoid of a molecular cavity—sheds a new light on the mechanisms of enantiorecognition by cyclodextrin derivatives. In contrast to cyclodextrins, linear dextrins are readily accessible in both enantiomeric forms. Chirality, 2007. © 2007 Wiley‐Liss, Inc.
Evaluation of enantioselective gas chromatography for the determination of minute deviations from racemic composition of α‐amino acids with emphasis on tyrosine: Accuracy and precision of the method
Authors: Reiner Clarissa , Nicholson Graeme J. , Nagel Ulrich , Schurig Volker 
Published: March 2007

AbstractWhereas the determination of high enantiomeric fractions (EF) of chiral compounds is very well established, the accurate determination of small deviations from racemic compositions has not yet received much attention despite its relevance to studies dealing with the origin of homochirality, where only small initial enantiomeric bias is expected. Racemic samples of representative α‐amino acids were derivatized as N‐(O,S)‐trifluoroacetyl/ethylesters and analyzed by enantioselective gas chromatography (GC) on fused silica capillaries coated with the chiral stationary phases (CSPs) Chirasil‐D‐Val, Chirasil‐L‐Val, and Lipodex E with GC/FID and GC/MS detection. The validation (accuracy and precision) of the determination of the enantiomeric fraction EF of the D‐enantiomer in racemic or near‐racemic compositions for 10 DL‐α‐amino acids obtained from commercial sources has been carried out. Emphasis is given to DL‐tyrosine, the enantiomers of which have recently been claimed to show different crystallization properties. Values of EF obtained from GC measurements using CSPs were compared with those from CE using chiral mobile phase additives. While the precision of the GC method is generally better than 0.08% for all DL‐α‐amino acids studied, accuracy (trueness) of determination of amino acids with polar side chains is poorer than expected from the precision as a result of systematic errors. The accuracy determined relied on measurements on two oppositely configurated CSPs. Chirality, 2007. © 2007 Wiley‐Liss, Inc.
Exploration on Regulating Factors for Proton Transfer along Hydrogen‐Bonded Water Chains
Authors: Yan Shihai , Zhang Liang , Cukier Robert I. , Bu Yuxiang 
Published: March 2007

AbstractProton transfer along a single‐file hydrogen‐bonded water chain is elucidated with a special emphasis on the investigation of chain length, side water, and solvent effects, as well as the temperature and pressure dependences. The number of water molecules in the chain varies from one to nine. The proton can be transported to the acceptor fragment through the single‐file hydrogen‐bonded water wire which contains at most five water molecules. If the number of water molecule is more than five, the proton is trapped by the chain in the hydroxyl‐centered H7O3+ state. The farthest water molecule involved in the formation of H7O3+ is the fifth one away from the donor fragment. These phenomena reappear in the molecular dynamics simulations. The energy of the system is reduced along with the proton conduction. The proton transfer mechanism can be altered by excess proton. The augmentation of the solvent dielectric constant weakens the stability of the system, but favors the proton transfer. NMR spin–spin coupling constants can be used as a criterion in judging whether the proton is transferred or not. The enhancement of temperature increases the thermal motion of the molecule, augments the internal energy of the system, and favors the proton transfer. The lengthening of the water wire increases the entropy of the system, concomitantly, the temperature dependence of the Gibbs free energy increases. The most favorable condition for the proton transfer along the H‐bonded water wire is the four‐water contained chain with side water attached near to the acceptor fragment in polar solvent under higher temperature.
On the effect of the rigid sidewall on the dynamic stiffness of embedded circular footings
Authors: Tassoulas John L. , Kausel Eduardo 
Published: March 2007

AbstractThe effect of the rigid sidewall, which is usually combined with embedded footings, on the dynamic stiffness of the footings is considered. An efficient numerical technique is used to calculate the static and dynamic stiffness of circular footings embedded in a stratum. The results show that the increase in static stiffness with increasing height of the sidewall is most significant in the case of rocking. The dynamic stiffness coefficients change considerably, if the sidewall extends higher than about half the depth of embedment. The damping coefficients corresponding to vertical vibrations and rocking are likewise affected by the height of the sidewall. The damping coefficients corresponding to torsional and horizontal vibrations increase considerably with increasing height of the sidewall.
Role of enzyme‐treated cells in RBC antibody screening using the gel test: a study of anti‐RH1, ‐RH2, and ‐RH3 antibodies
Authors: Conne Jocelyne , Schneider Philippe , Tissot Jean‐Daniel 
Published: March 2007

AbstractThe role of enzyme‐treated cells (ETCs) in red blood cell (RBC) antibody screening has been the subject of controversy, and its place in the clinical routine remains to be determined. In this work, plasma samples containing anti‐RH1 (anti‐D; N = 10), anti‐RH2 (anti‐C; N = 10), or anti‐RH3 (anti‐E; N = 10) antibodies were studied. The samples were diluted in nonbuffered or buffered normal saline, as well as in a pool of AB plasma samples. Titers and scores were determined by means of the gel test, using the indirect antiglobulin test (IAT) as well as ETCs, with R0r, r′r, or r″r test cells. Our results showed that compared to the IAT, ETCs allowed a clearer detection of anti‐RH2 and anti‐RH3, but not of anti‐RH1 antibodies. Based on our study, it is not clear whether the ETC phase of the gel test should be maintained for RBC antibody screening. J. Clin. Lab. Anal. 21:61–66, 2007. © 2007 Wiley‐Liss, Inc.
Woodchuck dendritic cells generated from peripheral blood mononuclear cells and transduced with recombinant human adenovirus serotype 5 induce antigen‐specific cellular immune responses
Authors: Ochoa‐Callejero Laura , Berraondo Pedro , Crettaz Julien , Olagüe Cristina , Vales África , Ruiz Juan , Prieto Jesús , Tennant Bud C. , Menne Stephan , González‐Aseguinolaza Gloria 
Published: March 2007

AbstractWoodchucks infected with the woodchuck hepatitis virus (WHV) is the best available animal model for testing the immunotherapeutic effects of dendritic cells (DCs) in the setting of a chronic infection, as woodchucks develop a persistent infection resembling that seen in humans infected with the hepatitis B virus. In the present study, DCs were generated from woodchuck peripheral blood mononuclear cells (wDCs) in the presence of human granulocyte macrophage colony‐stimulating factor (hGM‐CSF) and human interleukin 4 (hIL‐4). After 7 days of culture, cells with morphology similar to DCs were stained positively with a cross‐reactive anti‐human CD86 antibody. Functional analysis showed that uptake of FITC‐dextran by wDCs was very efficient and was partially inhibited after LPS‐induced maturation. Furthermore, wDCs stimulated allogenic lymphocytes and induced proliferation. Moreover, wDCs were transduced efficiently with a human adenovirus serotype 5 for the expression of β‐galactosidase. Following transduction and in vivo administration of such DCs into woodchucks, an antigen‐specific cellular immune response was induced. These results demonstrate that wDCs can be generated from the peripheral blood. Following transfection with a recombinant adenovirus wDCs can be used as a feasible and effective tool for eliciting WHV‐specific T‐cell responses indicating their potential to serve as prophylactic and therapeutic vaccines. J. Med. Virol. 79:522–529, 2007. © 2007 Wiley‐Liss, Inc.
Human herpesvirus 8 (HHV‐8) infection in healthy urban employees from Greece: Seroprevalence and associated factors
Authors: Zavitsanou Assimina , Sypsa Vana , Petrodaskalaki Maria , Kalapothaki Victoria , Whitby Denise , Hatzakis Angelos 
Published: March 2007

AbstractA cross‐sectional study was carried out in healthy company employees from Greece with the aim of assessing the prevalence of human herpesvirus 8 (HHV‐8) and identifying risk factors for this herpesviral infection. Serum samples obtained from 955 subjects were tested for antibodies to HHV‐8 by the K8.1 enzyme‐linked immunosorbent assay (ELISA). Associations between HHV‐8 serostatus and potential risk factors were examined using t‐test, chi square test, and multivariate logistic regression analysis. HHV‐8 prevalence was 7.6% (95% confidence interval (CI): 6.0%, 9.5%) and it increased with age from 6.5% among <30 years old to 13.8% among ≥50 years old subjects (P = 0.006). HHV‐8 seropositivity was independently associated with endoscopic examination (odds ratio (OR): 2.01; 95% CI: 1.09, 3.70; P = 0.026), HBsAg positivity (OR: 5.16; 95% CI: 2.02, 13.20; P = 0.001) and age (OR ≥50 years old vs. <50 years old: 2.09; 95% CI: 1.23, 3.52; P = 0.006). No statistically significant associations between HHV‐8 positive status and gender, occupational status, surgery, transfusion, tattoos/body piercing, multiple sex partners, weakness/fatigue, HCV status were observed. HHV‐8 is prevalent in Greece. The strong association between HBV infection and HHV‐8 positive status supports the hypothesis of an association between these two viral infections. The association between HHV‐8 seropositivity and endoscopic examination requires further investigation. J. Med. Virol. 79:591–596, 2007. © 2007 Wiley‐Liss, Inc.
Influence of HCV genotype and co‐infection with human immunodeficiency virus on CD4+ and CD8+ T‐cell responses to hepatitis C virus
Authors: Capa Laura , Soriano Vincent , García‐Samaniego Javier , Nuñez Marina , Romero Miriam , Cascajero Almudena , Muñoz Fernando , González‐Lahoz Juan , Benito José M. 
Published: March 2007

AbstractThe role of T‐cells in clearance of hepatitis C virus (HCV) during acute infection is critical. The relevance of the immunological response in the control of HCV replication is less clear in chronic HCV infection. HCV‐specific T‐cell responses were examined in 92 interferon‐naive individuals with chronic hepatitis C. A panel of 441 overlapping peptides spanning all expressed HCV proteins was used to measure HCV‐specific T‐cell responses, using flow cytometry after stimulating peripheral blood mononuclear cells (PBMCs) with different pools of these peptides. Most patients showed responses to at least one HCV protein, with NS5B for CD8+ responses and E2 for CD4+ responses identified most frequently. Both the prevalence and breadth of CD4+ and CD8+ responses were lower in co‐infected patients, independently of the HCV genotype. J. Med. Virol. 79:503–510, 2007. © 2007 Wiley‐Liss, Inc.
Signal polynomial smoothing from correlated interrupted observations based on covariances
Authors: Nakamori S. , Caballero‐Águila R. , Hermoso‐Carazo A. , Jiménez‐López J. D. , Linares‐Pérez J. 
Published: March 2007

AbstractThe least‐squares polynomial smoothing problem of discrete‐time signals from uncertain observations is addressed, when the variables describing the uncertainty are correlated at consecutive sampling times. Defining suitable augmented signal and observation vectors, the polynomial estimation problem is reduced to the linear estimation problem of the augmented signal. By an innovation
approach, recursive algorithms are derived for the augmented linear estimators without requiring the knowledge of the state‐space model generating the signal, but only covariance information of the processes involved. Copyright © 2007 John Wiley & Sons, Ltd.
Revisiting the constitutive equations of unsaturated porous solids using a Lagrangian saturation concept
Authors: Coussy O. 
Published: March 2007

AbstractThis paper aims at revisiting the constitutive equations of unsaturated porous solids at the light of a Lagrangian saturation concept. By referring the currently wetted porous volume to the reference configuration, the Lagrangian saturation is the state variable associated with the interfacial energy changes only, irrespective of the elastic energy required for deforming the solid matrix. The Lagrangian saturation concept provides the basis of a generic approach to the theory of poroelastoplasticity in unsaturated conditions. We successively examine the case where the saturating fluids occupy disconnected networks and the case where the networks are connected so that the saturating fluids can invade the porous solid or recede from it. The analysis provides the restricted situations where the averaged pore pressure may play the role of an effective pore pressure. Copyright © 2007 John Wiley & Sons, Ltd.
Modeling particle inflation from poly(amic acid) powdered precursors. I. Preliminary stages leading to bubble growth
Authors: Cano Camilo I. , Kyu Thein , Pipes R. Byron 
Published: March 2007

AbstractMorphological characteristics of polyimide microstructures obtained by solid‐state powder foaming determine the geometric properties of the unit cell, in polyimide foams prepared by this process. Morphological analysis of precursor particles has shown that particle size and shape, as well as the presence of embedded microvoids, exert a strong influence on the final microstructure morphology. Of equal importance in the morphological development are processing conditions such as heating rate and primary blowing agent content in the particles, prior to thermal treatment.In the present paper, the first of two numerical schemes is presented. A numerical model has been developed to study the preliminary stages that lead to particle inflation. Based on this model, a parametric analysis is performed for pertinent governing parameters, with the purpose of determining their effect on the onset of particle inflation and the potential morphological characteristics of polyimide microstructures. It has been found that precursor particle morphology and nuclei density are the key parameters in determining the potential morphology of the microstructures, by limiting the number of bubbles that grow within each particle. POLYM. ENG. SCI., 47:560–571, 2007. © 2007 Society of Plastics Engineers.
Predictions of two nonlinear viscoelastic constitutive relations for polymers under multiaxial loadings
Authors: Ellyin F. , Vaziri R. , Bigot L. 
Published: March 2007

AbstractTwo viscoelastic constitutive relations in differential form are further developed here to include material nonlinearity and distinction between loading and unloading regimes, which is a characteristic of polymers. The effects of hydrostatic pressure and anisotropy in tension and compression on the deformation response of polymers are accounted for through the definition of a pressure‐dependent equivalent stress. In the uniaxial stress state, these constitutive relations reduce to the two well‐known mechanical analogue representations: “Kelvin–Voigt‐type” and “Maxwell‐type” rheological models. The predictive capabilities of these constitutive relations are then assessed against a wide range of experimental results, which include both uniaxial and biaxial stress states subjected to quasi‐static and cyclic‐loading conditions. The predictions of both models are found to be in good agreement with the test data. POLYM. ENG. SCI., 47:593–607, 2007. © 2007 Society of Plastics Engineers.
Superabsorbent composite. XIII. Effects of Al3+‐attapulgite on hydrogel strength and swelling behaviors of poly(acrylic acid)/Al3+‐attapulgite superabsorbent composites
Authors: Zhang Junping , Zhao Yaogang , Wang Aiqin 
Published: March 2007

AbstractAl3+‐attapulgite (Al3+‐APT) was prepared by treating attapulgite (APT) with AlCl3 aqueous solution of various concentrations. The poly(acrylic acid)/Al3+‐attapulgite (PAA/Al3+‐APT) superabsorbent composite was prepared by reaction of partly neutralized acrylic acid, and Al3+‐APT in aqueous solution using N, N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The surface morphology of the composite was investigated by SEM, and the Al3+‐APT composite generated a relatively planar surface comparing the nature APT. The effects of Al3+‐APT on hydrogel strength and swelling behaviors, such as equilibrium water absorbency, swelling rate, and reswelling capability, of the superabsorbent composites were also studied. The hydrogel strength and reswelling capability were improved, however, the equilibrium water absorbency and swelling rate decreased with increasing AlCl3 solution concentration. The equilibrium water absorbency firstly increased, and then decreased with increasing Al3+‐APT content. The results indicate that Al3+‐APT acts as an assistant crosslinker in the polymeric network, which has great influences on hydrogel strength and swelling behaviors of the PAA/Al3+‐APT superabsorbent composites. POLYM. ENG. SCI., 47:619–624, 2007. © 2007 Society of Plastics Engineers.
Approximate prediction of gas core geometry in gas assisted injection molding using a short cut method
Authors: Polynkin A. , Pittman J.F.T. , Sienz J. 
Published: March 2007

AbstractA relatively cheap, short cut method for prediction of the form and location of the gas core, and the residual plastic wall thickness in gas assisted injection molding (GAIM) is described. The basis is a steady state, single phase solution for flow of the polymer melt through the channel of interest, without the need to model the gas penetration. The gas‐polymer interface position is predicted by an appropriately chosen isovel of the flow. For a prismatic or slowly varying channel, only a two‐dimensional developed flow solution is required. For more sharply varying cross sections, and where bends are present, a steady three‐dimensional (3D) solution is necessary. When a gas delay is used, during which polymer cools to the cavity walls, a solution for transient conduction in the static melt is carried out before the flow solution. By comparisons with the results of full 3D, transient, two‐phase simulations of GAIM, and with experimental results, the short cut method is shown to provide reasonable approximations, and in contrast to other currently used approximate methods, captures thickness variations around the circumference of noncircular channels. The asymmetric gas core location in bends is reproduced, as is the increased plastic wall thickness resulting from cooling during a gas delay. While the full analysis will still be required for complex parts and when high accuracy is required, the described short cut method is likely to prove useful in many other cases. POLYM. ENG. SCI., 47:713–720, 2007. © 2007 Society of Plastics Engineers.
Particle nucleation rates in continuous emulsion polymerisation reactors
Authors: Brooks Brian W. 
Published: March 2007

AbstractThe design of a continuous, stirred emulsion polymerisation reactor requires a detailed characterisation of the particle nucleation rate. Here, consideration is given to systems which use micelle‐forming surfactants and water‐insoluble monomers. The surfactant micelles will be considered to participate in two competing rate processes; the nucleation of polymer particles and dissolution into the aqueous phase.When the reactor operates in a steady state it is possible to obtain a size distribution function for the particles. This distribution function is used in the development of a number of diffusion equations and conservation equations. By making various sets of assumptions concerning the nucleation process, these equations are then used to obtain expressions for the particle number. By comparing the different models with experimental results it can be seen that satisfactory predictions for the particle number can be obtained without assuming that the polymer particles are always saturated with surfactant. The models also show that the radical absorption processes are not controlled by diffusion in the aqueous phase.In some cases the particle number does not reach a steady state but oscillates with time. The nature of these oscillations is described by the solution of nonlinear differential equations. Boundary conditions for these equations depend on the reaction conditions.