bluuebunny/crossref_metadata_2025 huggingface dataset:
Separation of hematopoietic stem and progenitor cells from human peripheral blood through polyurethane foaming membranes modified with several amino acids
Authors: Higuchi Akon , Yang Siou‐Ting , Li Pei‐Tsz , Chen Hui , Ruaan Ruoh‐Chyu , Chen Wen‐Yih , Chang Yung , Chang Yu , Tsai Eing Mei , Ling Qing‐Dong , Wang Han‐Chow , Hsu Shih‐Tien
Published: June 2009

The separation of hematopoietic stem and progenitor cells (CD34+ cells) from peripheral blood was investigated using foamed polyurethane (PU) membranes modified with several amino acids. CD34+ cells were collected by first allowing the blood to permeate through the membranes, and then passing the recovered solution through the membranes. Optimal conditions for the separation of CD34+ cells were investigated. The highest recovery ratio of CD34+ cells was obtained using three sheets of PU membranes having carboxylic acid groups (PUCOOH) modified with glycine, the membranes having been pretreated by immersion in phosphate buffer solution prior to permeation of blood. A high recovery ratio of CD34+ cells was achieved in a recovery process using 0.5 wt % human serum albumin (HSA) or 20% dextran solution passed through PUCOOH membranes. The recovery ratios of CD34+ cells using platelet‐poor plasma and platelet‐rich plasma were approximately 20% and 30%, respectively, significantly less than the ratio found using 0.5 wt % HSA solution. Surface‐modified membranes having carboxylic acid groups showed a higher recovery ratio of CD34+ cells than membranes having zwitterionic groups. The effect of carboxylic acid groups on the surface‐modified PU membranes was to generate weak interactions by electrostatic repulsion between CD34+ cells and the membranes because of the negatively charged surfaces of the cells, allowing them to be detached from the membranes and collected in the recovered solution. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of copolymers of alkyl‐ and azo‐thiophenes: Chromic properties and photoinduced birefringence
Authors: Gonçalves Vanessa C. , Costa Lígia M. M. , Cardoso Marcos R. , Mendonca Cleber R. , Balogh Débora T.
Published: June 2009

Polyazothiophene is a type of polythiophene derivative that combines the electrical and luminescent properties of polythiophenes with the photoisomerization property of azopolymers. Extensive efforts have been made to improve the properties of polyazothiophenes, such as solubility, optical, and chromic properties. We report the preparation of copolymers of an alkylthiophene (3‐octylthiophene, 3‐OT) and an azothiophene (2‐[N‐ethyl‐N‐[4‐[(4‐(4‐nitrophenyl)azo]phenyl]amino]ethyl 3‐thienylacetate, 3‐AzoT) in different ratios as an alternative route to improve these properties. The azosubstituted monomer contents in these copolymers were 6, 9, 12, and 51% (in mol), as evaluated by elemental analysis. Their chemical structures were confirmed by FTIR and 1H‐NMR. HPSEC and thermal analysis were used to characterize the polymers. The presence of thermochromic and solvatochromic properties was demonstrated by UV‐Vis spectroscopy. Optically induced birefringence was detected only in polymers with 12 and 51 mol % of azo‐units. The introduction of different ratios of the azothiophene in the copolymer alters the polymer solubility and emissive properties. The results indicate that the polyazothiophene copolymers presented are promising active layers for optical devices and sensors. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Chemical modification of polyethersulfone nanofiltration membranes: A review
Authors: Van der Bruggen B.
Published: June 2009

Polysulfone (PS) and poly(ether)sulfone (PES) are often used for synthesis of nanofiltration membranes, due to their chemical, thermal, and mechanical stability. The disadvantage for applying PS/PES is their high hydrophobicity, which increases membrane fouling. To optimize the performance of PS/PES nanofiltration membranes, membranes can be modified. An increase in membrane hydrophilicity is a good method to improve membrane performance. This article reviews chemical (and physicochemical) modification methods applied to increase the hydrophilicity of PS/PES nanofiltration membranes. Modification of poly(ether)sulfone membranes in view of increasing hydrophilicity can be carried out in several ways. Physical or chemical membrane modification processes after formation of the membrane create more hydrophilic surfaces. Such modification processes are (1) graft polymerization that chemically attaches hydrophilic monomers to the membrane surface; (2) plasma treatment, that introduces different functional groups to the membrane surface; and (3) physical preadsorption of hydrophilic components to the membrane surface. Surfactant modification, self‐assembly of hydrophilic nanoparticles and membrane nitrification are also such membrane modification processes. Another approach is based on modification of polymers before membrane formation. This bulk modification implies the modification of membrane materials before membrane synthesis of the incorporation of hydrophilic additives in the membrane matrix during membrane synthesis. Sulfonation, carboxylation, and nitration are such techniques. To conclude, polymer blending also results in membranes with improved surface characteristics. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Investigation of Pluronic© F127–Water solutions phase transitions by DSC and dielectric spectroscopy
Authors: Barba Anna Angela , d'Amore Matteo , Grassi Mario , Chirico Serafina , Lamberti Gaetano , Titomanlio Giuseppe
Published: June 2009

The water solutions of the block copolymers PEOn‐PPOm‐PEOn, known as pluronics, show a complex thermal behavior, since they are liquid at low temperature (5°C), and they can give soft gel when heated at body temperature (37°C). These properties are of great interest in biomedical applications. To properly design these applications, a prerequisite is the knowledge of the thermodynamics—how much—and of the kinetics—how fast—with which these transformations take place. In this work, solutions of F127 (the copolymer for which n = 100 and m = 65) were studied by varying the concentration and the temperature and analyzing their behavior when heated under several heating rates. The studies were performed by differential scanning calorimetry (DCS) and dielectric spectroscopy. The investigations carried out under equilibrium conditions allowed us to determine the thermodynamics of the phase transitions, whereas the investigations carried out under varying conditions allowed us to quantify the kinetics of the phase transitions. Empirical models were also proposed to describe both the thermodynamics and the kinetics observed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Chemical modification of unsaturated polyesters influence of polyester's structure on thermal and viscoelastic properties of low styrene content copolymers
Authors: Worzakowska Marta
Published: June 2009

In this study, the chemical modification of unsaturated polyesters and the influence of polyester's structure on thermal and viscoelastic properties have been presented. The structure of unsaturated polyesters obtained in polycondensation of cyclohex‐4‐ene‐1,2‐dicarboxylic anhydride (THPA), maleic anhydride and only one suitable symmetrical glycol: ethylene glycol or 1,4‐butanediol (BDO) or 1,6‐hexanediol has been modified by peracetic acid. The selective oxidation of unsaturated polyesters conducted in mild time and temperature conditions was a successful and effective method to prepare new materials/unsaturated epoxy polyesters/containing epoxy groups in cycloaliphatic rings and carbon–carbon double bonds in polyester chain. The unsaturated epoxy polyesters were capable of both copolymerization with vinyl monomer and polyaddition reactions with suitable curing agent. Therefore, they were successfully used as a component of low styrene content copolymers. As was confirmed by DSC, DMA, and TGA analyses, polyester's structure had significant influence on thermal and viscoelastic properties of styrene copolymers. The properties of styrene copolymers prepared from unsaturated epoxy polyesters were considerably better compared with those obtained for styrene copolymers from unsaturated polyesters.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Polymerization of fluoroacrylate and guar gum copolymer as a new pretreatment paste for ink‐jet printing of polyester
Authors: Chang Shiau‐Yin Peggy , Chao Yu‐Chou
Published: June 2009

A novel pretreatment paste containing fluoroacrylate copolymer and modified Guar Gum was carried out on the polyester fabric to provide partial water repellency and printability after inkjet printed with water‐based disperse dye inks. The stable fluorinated pastes were prepared via miniemulsion polymerization of fluoroalkyl acrylates, styrene, 2‐ethylhexyl acrylate, and modified guar gum in the presence of AIBN as initiator, CTAB and polyoxyethylene polyaryl ether as surfactants under suitable reaction conditions. In the analysis of monomer conversion and particle size, the highest polymerization rate with smallest particle size was obtained with increasing concentration of surfactants and initiator but the decreasing degree of substitution of guar gum to imply stronger interactions between fluoroacrylate monomers, hydroxyl groups of modified guar gum and EO units of nonionic surfactants. The 30% of stock fluorinated paste with urea concentration of 6% provided the prints with highest K/S value, satisfactory edge acuity and least color difference between front and back sides of the fabric to show more transparency. The rating 80 of water repellency tested on the best treated polyester fabric demonstrated stain proof properties after sprayed with water and dried. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of novel soluble cardo poly(arylene ether ketone)s containing xanthene structures
Authors: Sheng Shou‐Ri , Ge Wei‐Wei , Huang Zhen‐Zhong , Liu Xiao‐Ling , Song Cai‐Sheng
Published: June 2009

9,9‐Bis(4‐hydroxyphenyl)xanthene (BHPX), a bisphenol monomer, was synthesized in 82% yield from xanthenone in a one‐pot, two‐step synthetic procedure. Four novel aromatic poly(ether ketone)s (PEKs) based on BHPX were prepared via a nucleophilic aromatic substitution polycondensation with four difluorinated aromatic ketones. The polycondensation proceeded in tetramethylene sulfone in the presence of anhydrous potassium carbonate and afforded the new cardo PEKs in nearly quantitative yields with inherent viscosities of 0.77–0.85 dL/g. High molecular weight PEKs having number‐average molecular weights (Mn's) in the range of 38,900–40,600 g/mol with the polydispersity index ranged from 1.97 to 2.06 are all amorphous and show high glass transition temperatures ranging from 210°C to 254°C, excellent thermal stability, and the temperatures at the 5% weight loss are over 538°C with char yields above 60% at 700°C in nitrogen. These new PEKs are all soluble in polar aprotic solvents such as N‐methyl‐2‐pyrrolidone and N, N′‐dimethylacetamide and could also be dissolved in chloroform and tetrahydrofuran. All the polymers formed transparent, strong, and flexible films with tensile strengths of 78–84 MPa, Young's moduli of 2.54–3.10 GPa, and elongations at break of 14–18 %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Terminal functionalized hydroxyl‐terminated polybutadiene: An energetic binder for propellant
Authors: Shankar Rajavelu Murali , Roy Tapta Kanchan , Jana Tushar
Published: June 2009

We report the functionalization of hydroxyl terminated polybutadiene (HTPB) backbone by covalently attaching 1‐chloro‐2, 4‐dinitrobenzene (DNCB) at the terminal carbon atoms of the HTPB. The modification of the HTPB by the DNCB does not alter the unique physico–chemical properties and the microstructure of the parent HTPB. IR, 1H‐NMR, 13C‐NMR, size exclusion chromatography (SEC) and absorption spectroscopy studies prove that the DNCB molecules are covalently attached to the terminal carbon atoms of the HTPB. The π electron delocalization owing to long polymer chain, strong electron withdrawing effect of the DNCB molecule are the major driving forces for the covalent attachment of the DNCB at the terminal carbon atom of the HTPB. We are the first to observe the existence of intermolecular hydrogen bonding between the terminal hydroxyl groups of the HTPB. IR study shows that the attached DNCB molecules at the terminal carbon atoms of the HTPB breaks the intermolecular hydrogen bonding between the HTPB chains and forms a hydrogen bonding between the NO2 groups of the DNCB and the OH groups of the HTPB. Absorption spectral study of the modified HTPB indicates the better delocalization of π electron of butadiene due to the strong electron withdrawing effect of the DNCB molecules. Theoretical calculation also supports the existence of hydrogen bonding between the OH and NO2 groups. Theoretical calculation shows that the detonation performance of both the DNCB and the HTPB‐DNCB are promising. HTPB‐DNCB is the new generation energetic binder which has potential to replace the use of HTPB as binder for propellant.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Reconstructing the history of human impacts on coastal biodiversity in Chile: constraints and opportunities
Authors: Rivadeneira Marcelo M. , Santoro Calogero M. , Marquet Pablo A.
Published: June 2009

Although Chile is at the forefront in evaluating experimentally the importance of human harvesting impacts on coastal biodiversity, there are no evaluations of such impacts on a long‐term historical basis (tens to thousands of years). Different types of archival information (i.e. contemporaneous, archaeological, and palaeontological) were used to carry out a research programme based on the historical assessment of the impacts and intensity of resource extraction on coastal biodiversity along the Chilean coast.

In addition to recent scientific literature, different sources of contemporaneous information (e.g. museum collections, old reports and accounts) can reveal the human impacts observed in the more recent past. Furthermore, the large number of prehistoric shell middens along the entire Chilean coast offer access to ∼11 000 years of history along the entire coast, although the faunal composition, structure, and dynamics of most of them remain largely unstudied.

Finally, the rich and widespread fossil record of some marine groups provides the opportunity to reconstruct the structure and dynamics of benthic communities during different phases of human influence (e.g. pre‐human, prehistoric harvesting, and modern harvesting).

Preliminary comparisons of fossil versus modern bivalve assemblages suggest marked changes in the species composition. Human impacts seem very recent and shifts in the structure of benthic assemblages may have occurred only a few centuries/decades ago.

In contrast, prehistoric harvesting, although intense, was apparently not enough to cause a profound impact on coastal ecosystems. The approach herein envisaged can provide the basis to build a historical baseline to evaluate the human impacts on the coastal biodiversity in the region. Copyright © 2009 John Wiley & Sons, Ltd.
The Relationship Between the Lizard Eye and Associated Bony Features: A Cautionary Note for Interpreting Fossil Activity Patterns
Authors: Hall Margaret I.
Published: June 2009

Activity pattern, the time of day when an animal is active, is associated with ecology. There are two major activity patterns: diurnal (awake during the day in a photopic environment) and nocturnal (awake at night in a scotopic environment). Lizards exhibit characteristic eye shapes associated with activity pattern, with scotopic‐adapted lizard eyes optimized for visual sensitivity with large corneal diameters relative to their eye axial lengths, and photopic‐adapted lizards optimized for visual acuity, with larger axial lengths of the eye relative to their corneal diameters. This study: (1) quantifies the relationship between the lizard eye and its associated bony anatomy (the orbit, sclerotic ring, and associated skull widths); (2) investigates how activity pattern is reflected in that bony anatomy; and (3) determines if it is possible to reliably interpret activity pattern for a lizard that does not have the soft tissue available for study, specifically, for a fossil. Knowledge of extinct lizards' activity patterns would be useful in making paleoecological interpretations. Here, 96 scotopic‐ and photopic‐adapted lizard species are analyzed in a phylogenetic context. Although there is a close relationship between the lepidosaur eye and associated bony anatomy, based on these data activity pattern cannot be reliably interpreted for bony‐only specimens, such as a fossil, possibly because of the limited ossification of the lepidosaur skull. Caution should be exercised when utilizing lizard bony anatomy to interpret light‐level adaptation, either for a fossil lizard or as part of an extant phylogenetic bracket to interpret other extinct animals with sclerotic rings, such as dinosaurs. Anat Rec, 292:798–812, 2009. © 2009 Wiley‐Liss, Inc.
Worst‐case optimal control for an electrical drive system with time‐delay
Authors: Gao Yu , Kostyukova Olga , Chong Kil To
Published: June 2009

This paper considers an optimal control developed for an electrical drive system with a DC motor. Since it is a linear control system with input time‐delay subject to unknown but bounded disturbances, we construct a worst‐case feedback control policy, which can guarantee that, for all admissible uncertain disturbances, the real system state should be in a prescribed neighborhood of a desired value at the given final time, and the cost functional takes the best guarantee value. The worst‐case feedback control policy is allowed to be corrected at a given set of correction points between the initial and the final time, which is equivalent to solving a (m‐1)‐level min‐max problem. Since the min‐max problem at each stage does not yield a simple analytical solution, construction of the optimal policy is computationally prohibitive. This is why we consider an approximate control policy which is more convenient for computation. The simulation results illustrate that this proposed approach is feasible. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Bayesian modeling of financial returns: A relationship between volatility and trading volume
Authors: Abanto‐Valle Carlos A. , Migon Helio S. , Lopes Hedibert F.
Published: June 2009

The modified mixture model with Markov switching volatility specification is introduced to analyze the relationship between stock return volatility and trading volume. We propose to construct an algorithm based on Markov chain Monte Carlo simulation methods to estimate all the parameters in the model using a Bayesian approach. The series of returns and trading volume of the British Petroleum stock will be analyzed. Copyright © 2009 John Wiley & Sons, Ltd.
Application of a temperature‐dependent fluorescent dye (Rhodamine B) to the measurement of radiofrequency radiation‐induced temperature changes in biological samples
Authors: Chen Yuen Y. , Wood Andrew W.
Published: June 2009

We have applied a non‐contact method for studying the temperature changes produced by radiofrequency (RF) radiation specifically to small biological samples. A temperature‐dependent fluorescent dye, Rhodamine B, as imaged by laser scanning confocal microscopy (LSCM) was used to do this. The results were calibrated against real‐time temperature measurements from fiber optic probes, with a calibration factor of 3.4% intensity change °C−1 and a reproducibility of ±6%. This non‐contact method provided two‐dimensional and three‐dimensional images of temperature change and distributions in biological samples, at a spatial resolution of a few micrometers and with an estimated absolute precision of around 1.5 °C, with a differential precision of 0.4 °C. Temperature rise within tissue was found to be non‐uniform. Estimates of specific absorption rate (SAR) from absorbed power measurements were greater than those estimated from rate of temperature rise, measured at 1 min intervals, probably because this interval is too long to permit accurate estimation of initial temperature rise following start of RF exposure. Future experiments will aim to explore this. Bioelectromagnetics 30:583–590, 2009. © 2009 Wiley‐Liss, Inc.
Deutung vor der Deutung. Hermeneutische und geschlechtergeschichtliche Aspekte historiographischer Epochenbildung
Authors: Schnicke Falko
Published: June 2009

Interpretation before Interpretation. Aspects of Hermeneutics and Gender in Historiographical Periodization. This article focuses on different methods of periodization in modern German historiography. The time models used – as exemplified in studies on the history of biography – fundamentally preshape the represented past in heuristical and gender terms. That manifests itself principally in the fact that several authors, as well as various works by women writers and those excluded from academic circles, are conspicuously absent in certain models. What are ultimately not inconsiderable assumptions often go unacknowledged by the studies' authors, such that the epoch concepts they present are in themselves interpretations before the interpretations they explicitly aim to provide.
The blood platelets contribution to innate host defense – What they have learned from their big brothers
Authors: Zander Dorit M. W. , Klinger Matthias
Published: June 2009

Bactericidal effects of blood platelets have been known for more than 120 years, but the underlying mechanisms are largely obscure. Keeping in mind structural and functional analogies of platelets to neutrophils, three different mechanisms are thinkable: Engulfment of pathogens, release of microbicidal proteins, and production of reactive oxygen species (ROS). Here, we focus on the release of ROS and a possible contribution of blood plasma and thrombin to the bactericidal effects. Killing of bacteria was evaluated by DNA fluorescence labeling and electron microscopy. Release of ROS by platelets was measured photometrically by cytochrome C and phenol red/peroxidase assays and was further evaluated by topological methods. We found that (i) platelets produce 1500 times less O2– and 4000 times less H2O2 compared to neutrophils, (ii) ROS do not affect the killing rates, and (iii) no local enrichment of ROS was detectable. On the other hand, thrombin and plasma proteins with a molecular mass of >100 kDa are essential for bactericidal effects. We suggest that platelets contribute to the innate host defense by providing a catalytical surface for synthesis of thrombin. In the presence of a heat‐instable plasma protein, thrombin may generate a strong bactericidal complex, which is only effective in close vicinity to the platelet membrane.
Characterization of cell viability during bioprinting processes
Authors: Nair Kalyani , Gandhi Milind , Khalil Saif , Yan Karen Chang , Marcolongo Michele , Barbee Kenneth , Sun Wei
Published: June 2009

Bioprinting is an emerging technology in the field of tissue engineering and regenerative medicine. The process consists of simultaneous deposition of cells, biomaterial and/or growth factors under pressure through a micro‐scale nozzle. Cell viability can be controlled by varying the parameters like pressure and nozzle diameter. The process itself can be a very useful tool for evaluating an in vitro cell injury model. It is essential to understand the cell responses to process‐induced mechanical disturbances because they alter cell morphology and function. We carried out analysis and quantification of the degree of cell injury induced by bioprinting process. A parametric study with different process parameters was conducted to analyze and quantify cell injury as well as to optimize the parameters for printing viable cells. A phenomenological model was developed correlating the percentage of live, apoptotic and necrotic cells to the process parameters. This study incorporates an analytical formulation to predict the cell viability through the system as a function of the maximum shear stress in the system. The study shows that dispensing pressure has a more significant effect on cell viability than the nozzle diameter. The percentage of live cells is reduced significantly (by 38.75%) when constructs are printed at 40 psi compared to those printed at 5 psi.
Imaging ion flux and ion homeostasis in blood stage malaria parasites
Authors: Rohrbach Petra
Published: June 2009

The steady‐state regulation of intracellular levels of essential ions and ionic gradients is critical for almost all functions within a cell. Thus, it is not surprising to find that ions have been shown to play an important role in numerous parasitic processes, such as invasion, development and possibly drug resistance mechanisms. Live cell imaging has become a widespread technique to visualize and quantify several of these processes, including pH and Ca2+ homeostasis, in an effort to better understand the biology and physiology of cells. This is now also the case for many human pathogens. The aim of this review is to emphasize the importance of this technique and provide an overview of what we have learned so far, using the malaria parasite Plasmodium falciparum as a paradigm.
Probing vocal fold fibroblast response to hyaluronan in 3D contexts
Authors: Munoz‐Pinto Dany J. , Jimenez‐Vergara Andrea Carolina , Gelves L. Marcela , McMahon Rebecca E. , Guiza‐Arguello Viviana , Hahn Mariah S.
Published: June 2009

A number of treatments are being investigated for vocal fold (VF) scar, including designer implants. The aim of the present study was to validate a 3D model system for probing the effects of various bioactive moieties on VF fibroblast (VFF) behavior toward rational implant design. We selected poly(ethylene glycol) diacrylate (PEGDA) hydrogels as our base‐scaffold due to their broadly tunable material properties. However, since cells encapsulated in PEGDA hydrogels are generally forced to take on rounded/stellate morphologies, validation of PEGDA gels as a 3D VFF model system required that the present work directly parallel previous studies involving more permissive scaffolds. We therefore chose to focus on hyaluronan (HA), a polysaccharide that has been a particular focus of the VF community. Toward this end, porcine VFFs were encapsulated in PEGDA hydrogels containing consistent levels of high M w HA (${\rm HA}_{{\rm H}{M}_{\rm W} } $), intermediate Mw HA (${\rm HA}_{{\rm I}{M}_{\rm W} } $), or the control polysaccharide, alginate, and cultured for 7 and 21 days. ${\rm HA}_{{\rm H}{M}_{\rm W} } $ promoted sustained increases in active ERK1/2 relative to ${\rm HA}_{{\rm I}{M}_{\rm W} } $ . Furthermore, VFFs in ${\rm HA}_{{\rm I}{M}_{\rm W} } $ gels displayed a more myofibroblast‐like phenotype, higher elastin production, and greater protein kinase C (PkC) levels at day 21 than VFFs in ${\rm HA}_{{\rm H}{M}_{\rm W} } $ and alginate gels. The present results are in agreement with a previous 3D study of VFF responses to ${\rm HA}_{{\rm I}{M}_{\rm W} } $ relative to alginate in collagen‐based scaffolds permissive of cell elongation, indicating that PEGDA hydrogels may serve as an effective 3D model system for probing at least certain aspects of VFF behavior. Biotechnol. Bioeng. 2009; 104: 821–831 © 2009 Wiley Periodicals, Inc.
Model identification in presence of incomplete information by generalized principal component analysis: Application to the common and differential responses of Escherichia coli to multiple pulse perturbations in continuous, high‐biomass density culture
Authors: Guebel Daniel V. , Cánovas Manuel , Torres Néstor V.
Published: June 2009

In a previous report we described a multivariate approach to discriminate between the different response mechanisms operating in Escherichia coli when a steady, continuous culture of these bacteria was perturbed by a glycerol pulse (Guebel et al., 2009, Biotechnol Bioeng 102: 910–922). Herein, we present a procedure to extend this analysis when multiple, spaced pulse perturbations (glycerol, fumarate, acetate, crotonobetaine, hypersaline plus high‐glycerol basal medium and crotonobetaine plus hypersaline basal medium) are being assessed. The proposed method allows us to identify not only the common responses among different perturbation conditions, but to recognize the specific response for a given stimulus even when the dynamics of the perturbation is unknown. Components common to all conditions are determined first by Generalized Principal Components Analysis (GPCA) upon a set of covariance matrices. A metrics is then built to quantify the similitude distance. This is based on the degree of variance extraction achieved for each variable along the GPCA deflation processes by the common factors. This permits a cluster analysis, which recognizes several compact sub‐sets containing only the most closely related responsive groups. The GPCA is then run again but is restricted to the groups in each sub‐set. Finally, after the data have been exhaustively deflated by the common sub‐set factors, the resulting residual matrices are used to determine the specific response factors by classical principal component analysis (PCA). The proposed method was validated by comparing its predictions with those obtained when the dynamics of the perturbation was determined. In addition, it showed to have a better performance than the obtained with other multivariate alternatives (e.g., orthogonal contrasts based on direct GPCA, Tucker‐3 model, PARAFAC, etc.). Biotechnol. Bioeng. 2009; 104: 785–795 © 2009 Wiley Periodicals, Inc.
The effect of Bcl‐2, YAMA, and XIAP over‐expression on apoptosis and adenovirus production in HEK293 cell line
Authors: Sandhu Kalbinder Singh , Al‐Rubeai Mohamed
Published: June 2009

Many viruses induce cell death and lysis as part of their replication and dissemination strategy, and in many cases features of apoptosis are observed. Attempts have been made to further increase productivity by prolonging cell survival via the over‐expression of anti‐apoptotic genes. Here, we extend the study to investigate the association between virus replication and apoptosis, pertinent to large‐scale vector production for gene therapy. Infection of an HEK293 cell line with a replication defective type‐5‐adenovirus expressing a GFP reporter (Ad5GFP) resulted in rapid decline in viability associated with increased virus titer. The over‐expression of bcl‐2 resulted in improved cell resistance to apoptosis and prolonged culture duration, but reduced virus specific and total productivity. In contrast, the over‐expression of pro‐caspase‐3 (Yama/CPP32/apopain) resulted in reduced cell survival but increased virus productivity. The treatment of infected cells with caspase inhibitors support the preposition that caspase‐3 dependent apoptosis, and to a lesser degree caspase‐9 dependent apoptosis, represent important steps in virus production, thus implicating the intrinsic apoptosis pathway in the production of adenovirus from HEK293 cells. The suppression of apoptosis by the over‐expression of XIAP (inhibitors of caspase family cell death proteases) further shows that caspase‐mediated activation plays an important role in virus infection and maturation. Biotechnol. Bioeng. 2009; 104: 752–765 © 2009 Wiley Periodicals, Inc.
Shear stress magnitude and duration modulates matrix composition and tensile mechanical properties in engineered cartilaginous tissue
Authors: Gemmiti Christopher V. , Guldberg Robert E.
Published: June 2009

Cartilage tissue‐engineering strategies aim to produce a functional extracellular matrix similar to that of the native tissue. However, none of the myriad approaches taken have successfully generated a construct possessing the structure, composition, and mechanical properties of healthy articular cartilage. One possible approach to modulating the matrix composition and mechanical properties of engineered tissues is through the use of bioreactor‐driven mechanical stimulation. In this study, we hypothesized that exposing scaffold‐free cartilaginous tissue constructs to 7 days of continuous shear stress at 0.001 or 0.1 Pa would increase collagen deposition and tensile mechanical properties compared to that of static controls. Histologically, type II collagen staining was evident in all construct groups, while a surface layer of type I collagen increased in thickness with increasing shear stress magnitude. The areal fraction of type I collagen was higher in the 0.1‐Pa group (25.2 ± 2.2%) than either the 0.001‐Pa (13.6 ± 3.8%) or the static (7.9 ± 1.5%) group. Type II collagen content, as assessed by ELISA, was also higher in the 0.1‐Pa group (7.5 ± 2.1%) compared to the 0.001‐Pa (3.0 ± 2.25%) or static groups (3.7 ± 3.2%). Temporal gene expression analysis showed a flow‐induced increase in type I and type II collagen expression within 24 h of exposure. Interestingly, while the 0.1‐Pa group showed higher collagen content, this group retained less sulfated glycosaminoglycans in the matrix over time in bioreactor culture. Increases in both tensile Young's modulus and ultimate strength were observed with increasing shear stress, yielding constructs possessing a modulus of nearly 5 MPa and strength of 1.3 MPa. This study demonstrates that shear stress is a potent modulator of both the amount and type of synthesized extracellular matrix constituents in engineered cartilaginous tissue with corresponding effects on mechanical function. Biotechnol. Bioeng. 2009; 104: 809–820 © 2009 Wiley Periodicals, Inc.
Interactive engagement with embodied agents: an empirically validated framework
Authors: van Vugt H. C. , Hoorn J. F. , Konijn E. A.
Published: June 2009

This paper presents an empirically tested theoretical framework to explain user engagement and end‐user satisfaction with interactive agents. Such a framework is not only important from a scientific point of view; application designers may find a set of dos and don'ts that help them create more satisfying embodied agents in different task domains and social settings. From a multidisciplinary perspective, we have conducted a series of experiments to verify underlying mechanisms in the processes of interacting and engaging with embodied agents in various task domains. Our results show that the most commonly held views are not always tenable; sometimes other factors provide better explanations for liking an embodied agent or end‐user satisfaction. For example, it is not realism but rather affordances and ethics that are key for understanding user responses, and a beautiful design is not always the most preferable. From our results, guidelines for designers and future research are reflected upon. Copyright © 2009 John Wiley & Sons, Ltd.
Angular momentum guided motion concatenation
Authors: Shum Hubert P. H. , Komura Taku , Yadav Pranjul
Published: June 2009

In this paper, we propose a new method to concatenate two dynamic full‐body motions such as punches, kicks, and flips by using the angular momentum as a cue. Through the observation of real humans, we have identified two patterns of angular momentum that make the transition of such motions efficient. Based on these observations, we propose a new method to concatenate two full‐body motions in a natural manner. Our method is useful for applications where dynamic, full‐body motions are required, such as 3D computer games and animations. Copyright © 2009 John Wiley & Sons, Ltd.
Malonyl carba(dethia)‐ and Malonyl oxa(dethia)‐coenzyme A as Tools for Trapping Polyketide Intermediates
Authors: Tosin Manuela , Spiteller Dieter , Spencer Jonathan B.
Published: June 2009

Caught in a trap. In this study trapped polyketide species (see figure) were off‐loaded from a type III PKS by novel nonhydrolyzable malonyl coenzyme A analogues in which a methylene group or an oxygen atom replaces the sulfur atom of malonyl‐CoA. This strategy allows the straightforward characterisation of intermediates of polyketide biosynthesis by LC‐HR‐ESI‐MS/MS and provides valuable insights on the mechanism and timing of polyketide formation.

magnified image

In order to study intermediates in polyketide biosynthesis two nonhydrolyzable malonyl coenzyme A analogues were synthesised by a chemoenzymatic route. In these analogues the sulfur atom of CoA was replaced either by a methylene group (carbadethia analogue) or by an oxygen atom (oxadethia analogue). These malonyl‐CoA analogues were found to compete with the natural extender unit malonyl‐CoA and to trap intermediates from stilbene synthase, a type III polyketide synthase (PKS). From the reaction of stilbene synthase with its natural phenylpropanoid substrates, diketide, triketide and tetraketide species were successfully off‐loaded and characterised by LC‐MS. Moreover, the reactivity of the nonhydrolyzable analogues offers insights into the flexibility of substrate alignment in the PKS active site for efficient malonyl decarboxylation and condensation.
Under‐representation of women in high‐impact published clinical cancer research
Authors: Jagsi Reshma , Motomura Amy R. , Amarnath Sudha , Jankovic Aleksandra , Sheets Nathan , Ubel Peter A.
Published: June 2009

BACKGROUND.

Adequate representation of women in research has been deemed essential.

METHODS.

Cancer research published in 8 journals in 2006 was reviewed. The percentage of women among study participants was compared with the proportion expected from population‐based estimates of sex‐specific cancer incidence, using binomial tests. Differences were assessed in sex distribution of participants by funding source, author sex, and focus of research with the Student t test, and in a linear regression model controlling for cancer type.

RESULTS.

A total of 1534 cancer research articles were identified, of which 661 (representing 1,096,098 participants) were prospective clinical studies and were analyzed further. For all 7 non‐sex–specific cancer types assessed, the majority of studies analyzed included a lower proportion of women than the proportion of women among patients having cancer of that type in the general population. Among studies focusing on cancer treatment, women constituted a significantly lower overall proportion of the participants in the analyzed studies than expected for 6 of 7 non‐sex–specific cancer types (P < .001). Among non‐sex–specific studies, the mean percentage of participants who were women was 38.8%. Non‐sex–specific studies reporting government funding had a higher percentage of female participants (mean 41.3% vs 36.9%; P = .005). In a regression model controlling for cancer type, lack of government funding (P = .03) and focus on cancer treatment (P = .03) were found to be independent significant predictors of a lower percentage of female participants.

CONCLUSIONS.

Women were under‐represented as participants in recently published, high‐impact studies of non‐sex–specific cancers. Studies that received government funding included a higher proportion of female subjects. Cancer 2009. © 2009 American Cancer Society.
Computational modeling of electrocardiograms: A finite element approach toward cardiac excitation
Authors: Kotikanyadanam M. , Göktepe S. , Kuhl E.
Published: June 2009

The objective of this work is the computational simulation of a patient‐specific electrocardiogram (EKG) using a novel, robust, efficient, and modular finite element‐based simulation tool for cardiac electrophysiology. We apply a two‐variable approach in terms of a fast action potential and a slow recovery variable, whereby the latter phenomenologically summarizes the concentration of ionic currents. The underlying algorithm is based on a staggered solution scheme in which the action potential is introduced globally as nodal degree of freedom, while the recovery variable is treated locally as internal variable on the integration point level. We introduce an unconditionally stable implicit backward Euler scheme to integrate the evolution equations for both variables in time, and an incremental iterative Newton–Raphson scheme to solve the resulting nonlinear system of equations. In a straightforward post‐processing step, we calculate the flux of the action potential and integrate it over the entire domain to obtain the heart vector. The projection of the heart vector onto six pre‐defined directions in space defines a six‐lead EKG. We illustrate its generation in terms of a magnetic resonance‐based patient‐specific heart geometry and discuss the clinical implications of the computational electrocardiography. Copyright © 2009 John Wiley & Sons, Ltd.
Linguistic color image segmentation using a hierarchical Bayesian approach
Authors: Alarcón Teresa E. , Marroquín José L.
Published: June 2009

In this work, we combine Bayesian techniques with a color categorization model, which leads to a method for the linguistic segmentation of color images. The categorization model considers the 11 universal color categories proposed by Berlin and Kay [Basic Color Terms: Their Universality and Evolution.Berkeley: University of California; 1969]. The likelihood for each category is represented by a linear combination of quadratic splines, and as a result, each voxel in the color space L*u*v* is described as a vector of probabilities, whose components express the degree to which the voxel belongs to a given color category. This gives rise to a probabilistic dictionary which is used for the segmentation, in which prior spatial granularity constraints are incorporated via an entropy‐controlled quadratic Markov measure field (ECQMMF) model, as proposed by Rivera et al. [IEEE Trans Image Process 2007;16:3047–3057]. We give a generalization of ECQMMF that allows one to consider the perceptual interactions between the basic colors that were experimentally established by Boynton and Olson [Color Res Appl 1987;12:94–105]. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 299–309, 2009
Analysis and simulation of distributed T/H with averaging technique in folding and interpolating A/D converters
Authors: Zhang Chunming , Shao Zhibiao
Published: June 2009

Distributed track‐and‐hold (T/H) circuit is widely used in folding and interpolating analog‐to‐digital (A/D) converters as a good candidate of single T/H circuits for an optimum overall system performance. But, rigorous analysis and method for design do not exist. This paper brings averaging network to suppress the random offset voltages of the differential difference pre‐amplifiers (DDPAs), which locate before T/H circuit featuring two differential inputs for the requirement of fully differential A/D converters. The first contribution of this work is to present the exact expressions for the output voltage and gain in S‐domain, the integral nonlinearity (INL) and differential nonlinearity (DNL) in DDPAs through the further insight into this architecture. Furthermore, distortion resulting from settling time limitation, interpolation error, folder offset, and all sources of mismatch in averaged DDPAs is considered. In addition, the figure of merit for INL and DNL is proposed to quantify the effectiveness of averaging and be served as the guideline for the optimum design. Finally, these theoretical results were verified against Hspice simulations from a design example of distributed T/H circuits for 8‐bit 250 MHz folding and interpolating A/D converter, which confirmed the accurate and exhaustive analysis and exhibited a good agreement. Copyright © 2009 John Wiley & Sons, Ltd.
Piecewise linear second moment statistical simulation of ICs affected by non‐linear statistical effects
Authors: Biagetti Giorgio , Crippa Paolo , Curzi Alessandro , Orcioni Simone , Turchetti Claudio
Published: June 2009

This paper presents a methodology for statistical simulation of non‐linear integrated circuits affected by device mismatch. This simulation technique is aimed at helping designers maximize yield, since it can be orders of magnitude faster than other readily available methods, e.g. Monte Carlo. Statistical analysis is performed by modeling the electrical effects of tolerances by means of stochastic current or voltage sources, which depend on both device geometry and position across the die. They alter the behavior of both linear and non‐linear components according to stochastic device models, which reflect the statistical properties of circuit devices up to the second order (i.e. covariance functions). DC, AC, and transient analyses are performed by means of the stochastic modified nodal analysis, using a piecewise linear stochastic technique with respect to the stochastic sources, around a few automatically selected points. Several experimental results on significant circuits, encompassing both the analog and the digital domains, prove the effectiveness of the proposed method. Copyright © 2009 John Wiley & Sons, Ltd.
Long‐term effects of neonatal handling on mu‐opioid receptor levels in the brain of the offspring
Authors: Kiosterakis Georgios , Stamatakis Antonios , Diamantopoulou Anastasia , Fameli Maria , Stylianopoulou Fotini
Published: June 2009

Neonatal handling is an experimental paradigm of an early experience which permanently alters hypothalamic–pituitary–adrenal axis function resulting in increased ability to cope with stress, and decreased emotionality. In the present work we investigated the effect of neonatal handling on adult rat brain mu‐opioid receptor levels, since the opioid system is known to play an important role in emotional processing, anxiety and stress responses. Neonatal handling resulted in increased levels of mu‐opioid receptors in the basolateral and central amygdaloid nuclei, in the CA3 and CA4 hippocampal areas, in the ventral tegmental area, the nucleus accumbens and the prefrontal cortex. Handled animals of both sexes had lower anxiety as measured in the elevated plus maze. The increased mu receptor levels could participate in the molecular mechanisms underlying the well‐documented decreased stress and anxiety responses of handled animals. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 439–449, 2009.
A New Series of Anhydrous Lanthanide‐Based Octahedral Hexanuclear Complexes
Authors: Calvez Guillaume , Daiguebonne Carole , Guillou Olivier , Le Dret Florence
Published: June 2009

The synthesis of hexanuclear lanthanide oxido/hydroxido complexes by direct hydrolysis has been reinvestigated and optimized. Lanthanide oxido/hydroxido complexes of the general formula [Ln6O(OH)8(NO3)6(H2O)x]2NO3·2H2O (with x = 12 for Ln = Sm–Yb or Y, x = 14 for Ln = Pr or Nd, and x = 16 for Ln = Ce) have been obtained and characterized. The dehydration of all these complexes leads to isostructural anhydrous compounds with the general formula [Ln6O(OH)8(NO3)8]∞. The crystal structure has been solved on the basis of powder X‐ray diffraction of the Y‐containing compound. This compound crystallizes in the triclinic system, and the crystal structure can be described as the juxtaposition of infinite chains of hexanuclear complexes linked to each other by nitrate groups. These anhydrous compounds are readily soluble in most organic solvents and can be used as molecular precursors for further chemistry. When exposed to moisture, they rehydrate reversibly, which leads to their initial hydrated phase. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
N‐Amino‐exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimide as an Active Aminoaziridinating Agent
Authors: Zibinsky Mikhail , Stewart Timothy , Prakash G. K. Surya , Kuznetsov Mikhail A.
Published: June 2009

N‐Amino‐exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimide is active in the oxidative aminoaziridination reaction toward alkenes substituted with aryl‐, alkyl, and electron‐withdrawing groups, providing access to stable derivatives of N‐aminoaziridine. Yields varied from 19 to 76 %, and trans‐substituted alkenes reacted faster and gave better yields than cis‐alkenes. No products of self‐aziridination were isolated.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)