bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activators of P‐glycoprotein: Structure–Activity Relationships and Investigation of their Mode of Action
Authors: Sterz Katja , Möllmann Lars , Jacobs Anna , Baumert Dieter , Wiese Michael 
Published: September 2009

AbstractP‐glycoprotein (P‐gp), a 170 kDa plasma membrane protein, is one of the most relevant ABC transporters involved in the development of multidrug resistance (MDR). Understanding its mechanism of transport as well as its interactions with various substrates are basic requirements for the development of adequate therapeutic approaches to overcome this kind of resistance against a broad spectrum of structurally unrelated cytostatic drugs. P‐gp modulators (activators) that exert various effects on the intracellular accumulation of distinct P‐gp substrates are useful tools for investigating the interactions between multiple drug binding sites of this transport protein. In this study, a series of 27 different imidazobenzothiazoles and imidazobenzimidazoles structurally related to the known P‐gp activators QB102 and QB11 was designed, and their modulating properties were investigated. Most of them were able to stimulate P‐gp‐mediated efflux of daunorubicin and rhodamine 123 in a concentration‐dependent manner, but some compounds also displayed weak inhibitory effects. Additionally, P‐gp‐mediated efflux of vinblastine and colchicine was inhibited by several compounds. Therefore, we concluded that the novel compounds bind to the H site of P‐gp and activate the efflux of specific substrates of the R site in a positive cooperative manner, whereas binding of H‐type substrates is inhibited competitively. This hypothesis is confirmed by the observation that the modulators do not influence hydrolysis of ATP or its affinity toward P‐gp.
A microscopic competition model and its dynamics analysis on network attacks
Authors: Xiang Yang , Tian Daxin , Zhou Wanlei 
Published: September 2009

AbstractModeling network traffic has been a critical task in the development of Internet. Attacks and defense are prevalent in the current Internet. Traditional network models such as Poisson‐related models do not consider the competition behaviors between the attack and defense parties. In this paper, we present a microscopic competition model to analyze the dynamics among the nodes, benign or malicious, connected to a router, which compete for the bandwidth. The dynamics analysis demonstrates that the model can well describe the competition behavior among normal users and attackers. Based on this model, an anomaly attack detection method is presented. The method is based on the adaptive resonance theory, which is used to learn the model by normal traffic data. The evaluation shows that it can effectively detect the network attacks. Copyright © 2009 John Wiley & Sons, Ltd.
Rectification in Supramolecular Zinc Porphyrin/Fulleropyrrolidine Dyads Self‐Organized on Gold(111)
Authors: Matino Francesca , Arima Valentina , Piacenza Manuel , Della Sala Fabio , Maruccio Giuseppe , Phaneuf Ray J. , Del Sole Roberta , Mele Giuseppe , Vasapollo Giuseppe , Gigli Giuseppe , Cingolani Roberto , Rinaldi Ross 
Published: September 2009

AbstractSelf‐assembled donor/acceptor dyads are of current interest as they are biomimetic to the natural photosynthetic conversion system. Herein, we present an ultrahigh‐vacuum scanning tunneling microscopy and scanning tunneling spectroscopy (UHV‐STM/STS) study of ex situ self‐assembled supramolecular dyads consisting of fulleropyrrolidines (PyC2C60) axially ligated to zinc(II) tetraphenylporphyrin (ZnTPP), self organized on a 4‐aminothiophenol (4‐ATP) self‐assembled monolayer on gold(111). These dyads show both bias‐polarity‐dependent apparent height in STM images and highly rectifying behavior in tunneling spectroscopy. First‐principles density functional theory calculations clarify the conformational and electronic properties of the 4‐ATP/ZnTPP/PyC2C60 system. Interestingly, we find easier tunneling for electrons moving from the acceptor side of the dyads to the donor side, in the inverse‐rectifying sense with respect to previously reported molecular rectifiers. Such behavior cannot be explained as an elastic resonant tunneling process, but it can by using a model based on the Aviram–Ratner mechanism.
Dislocations and dislocation reduction in space grown GaSb
Authors: Danilewsky A. N. , Cröll A. , Tonn J. , Schweizer M. , Lauer S. , Benz K. W. , Tuomi T. , Rantamäki R. , McNally P. , Curley J. 
Published: September 2009

AbstractThe behaviour of dislocations in GaSb crystals grown in space both from a stoichiometric melt (floating zone method, FZ) and a Bi solution (floating solution zone, FSZ) respectively, is studied. Predominantly straight 60° dislocations with Burgers vectors of the type b = a/2 <110> in (111) glide planes are identified. In the 20 mm long FZ single crystal the linear growing out of the dislocations is observed which reduces the dislocation density in the centre of the crystal to values below 300 cm–2. The Bi incorporation in the FSZ crystal results in a misfit between seed and grown crystal and in a network of misfit dislocations at the interface. Thermocapillary convection during growth as well as the surface tension may be the reasons for the presence of curved dislocations and the higher dislocation density within a 1 – 2 mm border region at the edges of both of the crystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of NLO active lithium sulphate monohydrate single crystals
Authors: Priya R. , Krishnan S. , Raj C. Justin , Das S. Jerome 
Published: September 2009

AbstractSingle crystals of the NLO active lithium sulphate monohydrate were grown successfully by slow evaporation technique. The as‐grown crystal was clear, transparent and the size of the crystal attained was 14 x 8 x 5 mm3 within a period of 4 weeks. The crystal was subjected to Fourier transform infrared spectroscopy (FTIR), Thermal analysis (TG/DTA), UV‐Vis analysis, mechanical and dielectric studies. Theoretical calculations for band gap energy were made. An attempt was made to calculate polarizability by Penn analysis and compare with the traditional method and results are tabulated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influx of calcium through L‐type calcium channels in early postnatal regulation of chloride transporters in the rat hippocampus
Authors: Bray Jennifer G. , Mynlieff Michelle 
Published: September 2009

AbstractDuring the early postnatal period, GABAB receptor activation facilitates L‐type calcium current in rat hippocampus. One developmental process that L‐type current may regulate is the change in expression of the K+Cl− co‐transporter (KCC2) and N+K+2Cl− co‐transporter (NKCC1), which are involved in the maturation of the GABAergic system. The present study investigated the connection between L‐type current, GABAB receptors, and expression of chloride transporters during development. The facilitation of L‐type current by GABAB receptors is more prominent in the second week of development, with the highest percentage of cells exhibiting facilitation in cultures isolated from 7 day old rats (37.5%). The protein levels of KCC2 and NKCC1 were investigated to determine the developmental timecourse of expression as well as expression following treatment with an L‐type channel antagonist and a GABAB receptor agonist. The time course of both chloride transporters in culture mimics that seen in hippocampal tissue isolated from various ages. KCC2 levels increased drastically in the first two postnatal weeks while NKCC1 remained relatively stable, suggesting that the ratio of the chloride transporters is important in mediating the developmental change in chloride reversal potential. Treatment of cultures with the L‐type antagonist nimodipine did not affect protein levels of NKCC1, but significantly decreased the upregulation of KCC2 during the first postnatal week. In addition, calcium current facilitation occurs slightly before the large increase in KCC2 expression. These results suggest that the expression of KCC2 is regulated by calcium influx through L‐type channels in the early postnatal period in hippocampal neurons. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 2009
Retinoic acid receptors exhibit cell‐autonomous functions in cranial neural crest cells
Authors: Dupé Valérie , Pellerin Isabelle 
Published: September 2009

AbstractPrevious work has emphasized the crucial role of retinoic acid (RA) in the ontogenesis of the vast majority of mesenchymal structures derived from the neural crest cells (NCC), which migrate through, or populate, the frontonasal process and branchial arches. Using somatic mutagenesis in the mouse, we have selectively ablated two or three retinoic acid receptors (i.e., RARα/RARβ, RARα/RARγ and RARα/RARβ/RARγ) in NCC. By rigorously analyzing these mutant mice, we found that survival and migration of NCC is normal until gestational day 10.5, suggesting that RAR‐dependent signaling is not intrinsically required for the early steps of NCC development. However, ablation of Rara and Rarg genes in NCC yields an agenesis of the median portion of the face, demonstrating that RARα and RARγ act cell‐autonomously in postmigratory NCC to control the development of structures derived from the frontonasal process. In contrast, ablation of the three Rar genes in NCC leads to less severe defects of the branchial arches derived structures compared with Rar compound null mutants. Therefore, RARs exert a function in the NCC as well as in a separated cell population. This work demonstrates that RARs use distinct mechanisms to pattern cranial NCC. Developmental Dynamics 238:2701–2711, 2009. © 2009 Wiley‐Liss, Inc.
Neural stem cell self‐renewal requires the Mrj co‐chaperone
Authors: Watson Erica D. , Mattar Pierre , Schuurmans Carol , Cross James C. 
Published: September 2009

AbstractThe Mrj co‐chaperone is expressed throughout the mouse conceptus, yet its requirement for placental development has prohibited a full understanding of its embryonic function. Here, we show that Mrj−/− embryos exhibit neural tube defects independent of the placenta phenotype, including exencephaly and thin‐walled neural tubes. Molecular analyses revealed fewer proliferating cells and a down‐regulation of early neural progenitor (Pax6, Olig2, Hes5) and neuronal (Nscl2, SCG10) cell markers in Mrj−/− neuroepithelial cells. Furthermore, Mrj−/− neurospheres are significantly smaller and form fewer secondary neurospheres indicating that Mrj is necessary for self‐renewal of neural stem cells. However, the molecular function of Mrj in this context remains elusive because Mrj does not colocalize with Bmi‐1, a self‐renewal protein. Furthermore, unlike in Mrj−/− placentas, intermediate filament‐containing aggregates do not accumulate in Mrj−/− neuroepithelium, ruling out nestin as a substrate for Mrj. Regardless, Mrj plays an important role in neural stem cell self‐renewal. Developmental Dynamics 238:2564–2574, 2009. © 2009 Wiley‐Liss, Inc.
Prdm1a is necessary for posterior pharyngeal arch development in zebrafish
Authors: Birkholz Denise A. , Killian Eugenia C. Olesnicky , George Kathleen M. , Artinger Kristin Bruk 
Published: September 2009

AbstractMultiple tissue interactions and signaling within the pharyngeal arches are required for development of the craniofacial skeleton. Here, we focus on the role of the transcription factor prdm1a in the differentiation of the posterior skeleton. prdm1a is expressed in the presumptive pharyngeal arch region and later in an endodermal pouch, the otic vesicle, and pharyngeal teeth. prdm1a mutants display a reduction in pharyngeal arch markers, a loss of posterior ceratobranchial cartilages, and a reduction in most neural crest–derived dermal bones. This is likely caused by a decrease in the number of proliferating cells but not an increase in cell death. Finally, a reduction in two key developmental signaling pathways, Fgf and retinoic acid, alters prdm1a expression, suggesting that prdm1a expression is mediated by these signaling pathways to pattern the posterior craniofacial skeleton. Together, these results indicate an essential role for prdm1a in the development of the zebrafish craniofacial skeleton. Developmental Dynamics 238:2575–2587, 2009. © 2009 Wiley‐Liss, Inc.
Bit‐length expansion for digital images
Authors: Kimura Tomoaki , Taguchi Akira 
Published: September 2009

AbstractBit‐length of digital images is decided by the Analog‐to‐Digital (AD) converter. The bit‐length expansion technique is necessary for high‐quality displays such as the liquid crystal display (LCD) and the plasma display. Bit‐length expansion is also necessary for low‐bit length images, which are degraded by the pseudo‐contour. In this paper, we propose a bit‐length expansion method from M‐level to N‐level [N=3(M−1)+1]. This operation means that two quantization levels are introduced between existing levels. The bit‐length expansion method results in the estimation problem of an error image between an M‐level's image and an N‐level's image. The error image is the pattern image which consists of three values. We show the estimation method of the three values pattern image and that the proposed method can remove the pseudo‐contour of digital images through several application results. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(10): 32–40, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10105
Group management of RFID passwords for privacy protection
Authors: Kobayashi Yuichi , Kuwana Toshiyuki , Taniguchi Yoji , Komoda Norihisa 
Published: September 2009

AbstractWhen an RFID tag is used in the whole item lifecycle including a consumer scene or a recycle scene, we have to protect consumer privacy in the state that the RFID tag is stuck on an item. We use the low‐cost RFID tag that has the access control function using a password, and we propose a method which manages RFID tags by passwords identical to each group of RFID tags. This proposal improves the safety of the RFID system because the proposed method is able to reduce the traceability for an RFID tag, and hold down the influence for disclosure of RFID passwords in both scenes. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(10): 24–31, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10106
A Simple Electrochemical Approach Based on Inexpensive Wall‐Jet Screen‐Printed Ring Disk Electrode to Evaluate Oxygen Reduction Catalysts
Authors: Yang Ting‐Hao , Liao Chun‐Yen , Chang Jen‐Lin , Lien Chien‐Hung , Zen Jyh‐Myng 
Published: September 2009

AbstractA simple electrochemical approach to evaluate oxygen reduction catalysts using an inexpensive screen‐printed ring disk carbon electrode system, consisting of a ring electrode deposited with MnO2 and a disk electrode modified with the catalysts for study, is developed in this study. The as‐prepared MnO2 is selective and sensitive for H2O2 oxidation in the presence of O2 and is crucial to the proposed approach. By coupling with a wall‐jet electrochemical cell, the product generated from the reduction reaction at the disk electrode can effectively be monitored at the MnO2‐deposited ring electrode. Model catalysts of nano‐Au and nano‐Pd representing 2e− reduction of O2 to H2O2 and 4e− reduction to H2O, respectively, were evaluated as electrode materials in oxygen reduction reaction to demonstrate the applicability of the proposed method.
1H‐NMR spectroscopic study of the effect of aging vascular prostheses made of poly(ethylene terephthalate) on the macromolecular weight
Authors: Chaouch W. , Dieval F. , Le Nouen D. , Defoin A. , Chakfe N. , Durand B. 
Published: September 2009

AbstractTrichloroacetyl isocyanate reacts rapidly and quantitatively with both acid and hydroxyl chain ends to form derivatives that can be readily determined by 1H‐NMR spectroscopy. This method provides a convenient mean for characterization of polyethylene terephthalate (PET) end‐groups. The 1H‐NMR spectroscopy has been applied to describe the chemical aging of the PET vascular prostheses by determination of the hydroxyl and carboxyl end‐group concentrations and therefore the macromolecular weight. To validate 1H‐NMR results, we used chemical titration of the end‐groups and classical viscosimetric method as complementary techniques. The analyses made on the explants of different lifetime demonstrated a significant deterioration compared with the virgin prostheses. A high degradation of macromolecular weight is observed. This phenomenon is explained by a random scission of the ester linkages. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Model studies of the optical rotation, and theoretical determination of its sign for β‐pinene and trans‐pinane
Authors: Baranowska Angelika , Ła̧czkowski Krzysztof Z. , Sadlej Andrzej J. 
Published: September 2009

AbstractWe have carried out extensive studies on the basis set dependence of the calculated specific optical rotation (OR) in molecules at the level of the time–dependent Hartree–Fock and density functional approximations. To reach the limits of the basis set saturation, we have devised an artificial model, the asymmetrically deformed (chiral) methane (CM) molecule. This small system permits to use basis sets which are prohibitively large for real chiral molecules and yet shows all the important features of the basis set dependence of the OR values. The convergence of the OR has been studied with n‐aug‐cc‐pVXZ basis sets of Dunning up to the 6–ζ. In a parallel series of calculations, we have used the recently developed large polarized (LPolX) basis sets. The relatively small LPolX sets have been shown to be competitive to very large n‐aug‐cc‐pVXZ basis sets. The conclusions reached in calculations of OR in CM concerning the usefulness of LPolX basis sets have been further tested on (S)‐methyloxirane and (S)‐fluoro‐oxirane. The smallest set of the LPolX family (LPol–ds) has been found to yield OR values of similar quality as those obtained with much larger Dunning's aug‐cc‐pVQZ basis set. These results have encouraged us to carry out the OR calculations with LPol–ds basis sets for systems as large as β‐pinene and trans‐pinane. In both cases, our calculations have lead to the correct sign of the OR value in these molecules. This makes the relatively small LPol–ds basis sets likely to be useful in OR calculations for large molecules. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010
MMP‐mediated collagen breakdown induced by activated protein C in equine cartilage is reduced by corticosteroids
Authors: Garvican Elaine R. , Vaughan‐Thomas Anne , Redmond Colette , Gabriel Natalie , Clegg Peter D. 
Published: September 2009

AbstractThe plasma serine protease activated protein C (APC) is synthesized by human chondrocytes at sites of pathological cartilage fibrillation. APC levels are increased in osteoarthritis (OA) synovial fluid, and in vitro APC has been shown to synergize with interleukin‐1β (IL‐1) to promote degradation from ovine cartilage. A model of equine cartilage degradation was established and used to explore corticosteroid activities. Intraarticular corticosteroids are a commonly prescribed treatment for joint disease, however their role in disease modification remains unclear. APC synergized with IL‐1 or tumor necrosis factor‐α (TNFα), promoting significant collagen degradation from equine cartilage explants within 4 days, but did not augment glycoaminoglycan (GAG) release. APC activated pro‐matrix metalloproteinases (MMP)‐2 but not pro‐MMP‐9, as assessed by gelatin zymography. APC did not directly activate pro‐MMP‐13. Dexamethasone, triamcinolone, and methylprednisolone acetate (MPA) were evaluated at concentrations between 10− 5M and 10−10M. High concentrations significantly increased GAG release from IL‐1+APC–treated explants. With the exception of MPA at 10−10M, all concentrations of corticosteroids caused significant decreases in IL‐1+APC‐driven hydroxyproline loss. Treatment with corticosteroids suppressed expression of MMP‐1, ‐3, and ‐13 mRNA. The collagenolysis associated with IL‐1+APC synergy, and the inhibition of this effect by corticosteroids may involve gelatinase activation and downregulation of MMP expression, respectively. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:370–378, 2010
The effect of strain rate on mechanical properties of cold forming sheet metals
Authors: Durmuş A. 
Published: September 2009

AbstractTensile mechanical properties of DIN EN 10268–1999 cold forming sheet metals were investigated within a strain rate range from 1.10‐4 to 1.10‐1 s‐1 using conventional tensile testing machine. This investigation also examined the influence of heat treatment on the mechanical properties of this material. The specimens were initially austenitized at 930 oC for 40 min and then water quenched. After reheated to 890, 850 and 810 oC, these were hold for 60 min and then water quenched as intermediate heat treatment. Consequently, it was determined that the yield and ultimate strength were increased 21 % and 7 % for the maximum value of strain rate, respectively. However, the failure strains were not notable affected with strain rate. For the heat treated materials, the considerable changing in mechanical properties was obtained at the 810oC annealing temperature.
Explosive scarf welding of aluminum to copper plates and their interface properties
Authors: Ashani J. Z. , Bagheri S. M. 
Published: September 2009

AbstractExplosive welding was used to produce scarf joint between aluminum and copper plates. This process is known as explosive scarf welding (ESW). In a scarf joint, the final bond interface is oblique. In this study, chamfered end of aluminum and copper plates were joined explosively and named scarf joint, employing changes in chamfered angle at different stand‐off distance and explosive loading. The geometry of scarf joint enables consideration of both flyer and base plate thickness and explosive loading and the effects on mechanical properties of interface such as bond shear strength and micro‐hardness can be investigated.Mathematical models developed on the interface properties of scarf joint to make relationship between the bond shear strength and explosive loading ratio. To check the adequacy of developed models, mechanical properties of interface, such as bond shear strength was predicted and compared with actual values in explosive cladding process. The results show reasonable agreement with theoretical predictions.Consequently, mathematical model which is based on scarf joints, can predict bond shear strength of cladding metals under desired explosive loading and flyer plate thickness.
Synthesis and characterization of novel biodegradable pentablock copolymers from L‐lactide, p‐dioxanone and poly (ethylene glycol)
Authors: Abdouss M. , Mehdi Hoseini S. , Mohammadi‐Rovshandeh J. , Javanbakht Mehran 
Published: September 2009

AbstractABCBA type pentablock copolymers, in which the A, B and C blocks are poly (p‐Dioxanone) (PPDO), poly (L‐Lactide) (PLLA), and polyethylene glycol (PEG), respectively, were synthesized via a two‐step ring‐opening polymerization in bulk using stannous octoate as the catalyst. PLA‐b‐PEG‐b‐PLA Triblock copolymer was synthesized at first and then p‐Dioxanone monomers as the other blocks were added to it. In the first step, poly ethylene glycol and, in the second step, triblock copolymer acts as the macro initiator. The obtained copolymers were identified by ⊃1&&sol;sup;H&&sol;I;, ⊃13&&sol;sup;CNMR&&sol;I; and IR&&sol;I; spectroscopy. The intrinsic viscosity of copolymers was measured in chloroform/phenol (3/1 v/w) solution. The thermal properties, such as melting point, melting enthalpy and crystallinity, were studied. From the results of differential scanning calorimetry and thermal gravimetric analysis, it was observed that the PPDO blocks show similar crystallization behavior like homopolymer and also melting temperature of two PPDO end blocks raise with an increase in DON content in copolymer.