bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of cytoplasmic polyadenylation element sequence on mRNA abundance during porcine embryogenesis and parthenogenetic development
Authors: Dobbs Kyle B. , Spollen William G. , Springer Gordon , Prather Randall S. 
Published: July 2010

AbstractDevelopment of a porcine germinal vesicle oocyte (GVO) to a 4‐cell stage embryo occurs during a transcriptionally silent period when the oocyte/embryo relies on maternally derived mRNA to encode proteins required for development. Regulation of translation and degradation of maternal mRNA is thought to be partially dependent on cytoplasmic polyadenylation elements (CPEs) within the 3′ untranslated region of the mRNA. The goal of this study was to determine how CPE sites affect the abundance of mRNA during embryogenesis and parthenogenetic development, and how cordycepin, a 3′‐deooxyadenosine (3′‐dA) that inhibits poly‐(A) tail formation, affects polyadenylation and transcript abundance. Expressed sequence tags (ESTs) from oocytes and 4‐cell stage embryos were scanned for the presence of five consensus CPEs. Nineteen different transcripts containing one to three CPEs were selected, and transcript abundance was determined in GVO, metaphase II, 2‐cell, and 4‐cell stage embryos via real‐time PCR while the length of the poly‐(A) tail was determined by using a poly‐(A) tail PCR (PAT) assays. Real‐time PCR was performed on three biological and two technical replicates for each stage. There was no direct correlation between poly‐(A) tail length, transcript abundance, and the CPE. In addition, the abundance of some messages was different if the embryo was the result of parthenogenetic activation. Cordycepin prevented polyadenylation of transcripts that normally undergo noticeable polyadenylation. Thus, CPEs may not be the only factors that regulate message stability, and parthenogenetic activation does not result in changes in transcript abundance that mimic in vitro fertilization. Mol. Reprod. Dev. 77: 699–709, 2010. © 2010 Wiley‐Liss, Inc.
Ein molekulares Korrosionsmodell für Metalle?
Authors: Neumaier Marco , Köppe Ralf , Schnöckel Hansgeorg 
Published: July 2010

AbstractMarco Neumaier, Ralf Köppe, Hansgeorg SchnöckelImmer noch sind die atomaren Prozesse, die bei der Oxidation von Metalloberflächen stattfinden, weitgehend unverstanden. Massenspektrometrische und quantenchemische Methoden zeigen, dass in der Reaktion der Modellverbindung Al13− mit Sauerstoff der Spinzustand des O2‐Moleküls für die Reaktivität eine entscheidende Rolle spielt.
“Man kann die Natur nicht überlisten”
Authors: Zbikowski Frauke 
Published: July 2010

AbstractDen Forschern in der Pharmaindustrie, Chemikern wie Biologen, diktiert die Natur die Bedingungen.Davon ist Werner Kramer, Geschäftsführer Forschung und Entwicklung von Sanofi‐Aventis Deutschland, überzeugt. Mit dem Chemiker und Arzt sprachen die Nachrichten aus der Chemie.
Aminierungen: die C‐H‐Bindung als funktionelle Gruppe
Authors: von Zezschwitz Paultheo 
Published: July 2010

AbstractPaultheo von ZezschwitzGut verfügbare Metallkomplexe ermöglichen hochselektive Nitren‐Insertionen in C‐H‐Bindungen. Dabei bilden sich intermolekular sekundäre Amide, intramolekular dagegen verschiedenartige Heterocyclen. Ausgehend von Aziden wurden kürzlich Heteroaromaten synthetisiert.
Real‐time‐PCR als Alternative
Authors: Kiehne Matthias , Grönewald Cordt , Junge Benjamin , Musiol Tanja 
Published: July 2010

AbstractMatthias Kiehne, Cordt Grönewald, Benjamin Junge, Tanja MusiolSchnellmethoden auf PCR‐Basis können mikrobiologische Methoden in der Lebensmittelprüfung ersetzen, denn sie sind weniger zeitintensiv und arbeiten häufig spezifischer.
Cofaktoren bestimmen: Absorption oder Fluoreszenz
Authors: Held Paul , Bruss Martina 
Published: July 2010

AbstractPaul Held, Marina BrussViele biologische Assays basieren auf dem oxidativen Status der Coenzyme Nicotinamid‐Adenin‐Dinucleotid oder Nicotinamid‐Adenin‐Dinucleotid‐Phosphat. Da sich die reduzierten Formen dieser Moleküle in ihrer Lichtabsorptionsfähigkeit von den oxidierten Formen unterscheiden, lassen sich Reaktionen anhand der Lichtabsorption oder Fluoreszenzemission quantifizieren.
em. Prof. Dr. Thomas Schönfeld
Authors: Komarek Kurt 
Published: July 2010

AbstractAm 22. Mai 2008 ging em. Prof. Dr. Thomas Schönfeld nach langer, geduldig und tapfer ertragener Krankheit von uns, ein Wissenschaftler und Universitätslehrer, dessen Leben mit Überzeugung und Hingabe der Wissenschaft − Forschung und Lehre − gewidmet war.
Wenn Bakterien kleben bleiben
Authors: Hartmann Mirja , Lindhorst Thisbe K. 
Published: July 2010

AbstractMirja Hartmann, Thisbe K. LindhorstBakterien besiedeln Zelloberflächen in gewaltiger Zahl. Unter dem Elektronenmikroskop betrachtet, könnte man ein adhäsives Escherichia‐coli‐Bakterium für eine winzig kleine Klette halten. Haben Kletten und Bakterien tatsächlich etwas gemeinsam?
Die Karl‐Ziegler‐Stiftung
Authors: Zörlein Caroline 
Published: July 2010

AbstractInnerhalb der letzten 15 Jahre hat die Gesellschaft Deutscher Chemiker sechs Stiftungen eingerichtet, die sie treuhänderisch verwaltet. Diese unselbständigen gemeinnützigen Stiftungen fördern mit Auszeichnungen und Stipendien den wissenschaftlichen Nachwuchs auf unterschiedlichen Gebieten der Chemie.
Werden Sie Mitglied: Gründung der GDCh‐AG Fluorchemie
Authors: Lehmann Thomas 
Published: July 2010

AbstractFluor spielt wie kein anderes Element eine herausragende Rolle in vielen Bereichen der Grundlagen‐ und angewandten Chemie, der Lebenswissenschaften sowie der Industrie und Technik. Die Fluorchemie ist stark interdisziplinär ausgerichtet und lässt sich nicht einem der traditionellen Bereiche der Chemie zuordnen.
Gebremste Konsolidierung
Authors: Schneider Bernd W. 
Published: July 2010

AbstractBernd W. SchneiderIm ersten Halbjahr ging die Transaktionsaktivität innerhalb der Chemiebranche gegenüber dem Vorjahr zurück. Im zweiten Halbjahr angekündigte Großübernahmen in der Spezialchemie können dieses Jahr dennoch zum Rekordjahr machen. Dies zeigt der zweite Quartalsbericht zu Fusionen und Übernahmen.
Pestizidrückstände in Salat bestimmen
Authors: Steiniger David , Butler Jessie , Philips Eric 
Published: July 2010

AbstractDavid Steiniger, Jessie Butler, Eric PhilipsDie Kombination aus einer schnellen Probenvorbereitungsmethode und Gaschromatographie, gekoppelt mit Tandem‐Massenspektrometrie erzielt Nachweisgrenzen bei gängigen Pestiziden zwischen 0, 9 und 4 ng·g−1.
Two‐fluid model with interface sharpening
Authors: Štrubelj L. , Tiselj I. 
Published: July 2010

AbstractTwo‐fluid models are applicable for simulations of all types of two‐phase flows ranging from separated flows with large characteristic interfacial length scales to highly dispersed flows with very small characteristic interfacial length scales. The main drawback of the two‐fluid model, when used for simulations of stratified flows, is the numerical diffusion of the interface. Stratified flows can be easily and more accurately solved with interface tracking methods; however, these methods are limited to the flows, that do not develop into dispersed types of flows. The present paper describes a new approach, where the advantage of the two‐fluid model is combined with the conservative level set method for interface tracking. The advection step of the volume fraction transport equation is followed by the interface sharpening, which preserves the thickness of the interface during the simulation. The proposed two‐fluid model with interface sharpening was found to be more accurate than the existing two‐fluid models. The mixed flow with both: stratified and dispersed flow, is simulated with the coupled model in this paper. In the coupled model, the dispersed two‐fluid model and two‐fluid model with interface sharpening are used locally, depending on the parameter which recognizes the flow regime. Copyright © 2010 John Wiley & Sons, Ltd.
Contact algorithms for the material point method in impact and penetration simulation
Authors: Huang P. , Zhang X. , Ma S. , Huang X. 
Published: July 2010

AbstractThe inherent no‐slip contact constraint in the standard material point method (MPM) creates a greater penetration resistance. Therefore, the standard MPM was not able to treat the problems involving impact and penetration very well. To overcome these deficiencies, two contact methods for MPM are presented and implemented in our 3D explicit MPM code, MPM3D. In MPM, the impenetrability condition may not satisfied on the redefined regular grid at the beginning of each time step, even if it has been imposed on the deformed grid at the end of last time step. The impenetrability condition between bodies is only imposed on the deformed grid in the first contact method, while it is imposed both on the deformed grid and redefined regular grid in the second contact method. Furthermore, three methods are proposed for impact and penetration simulation to determine the surface normal vectors that satisfy the collinearity conditions at the contact surface. The contact algorithms are verified by modeling the collision of two elastic rings and sphere rolling problems, and then applied to the simulation of penetration of steel ball and perforation of thick plate with a particle failure model. In the simulation of elastic ring collision, the first contact algorithm introduces significant disturbance into the total energy, but the second contact algorithm can obtain the stable solution by using much larger time step. It seems that both contact algorithms give good results for other problems, such as the sphere rolling and the projectile penetration. Copyright © 2010 John Wiley & Sons, Ltd.
Thermal stability and dynamic mechanical behavior of exfoliated graphite nanoplatelets‐LLDPE nanocomposites
Authors: Kim Sumin , Do Inhwan , Drzal Lawrence T. 
Published: July 2010

AbstractThe objective of this research was to investigate thermal stability and dynamic mechanical behavior of Exfoliated graphite nanoplatelets (xGnP™)‐Linear Low‐Density Poly Ethylene (LLDPE) nanocomposites with different xGnP loading content. The xGnP‐LLDPE nanocomposites were fabricated by solution and melt mixing in various screw rotating systems such as co‐, counter‐, and modified‐corotating. The storage modulus (E′) of the composites at the starting point of −50°C increased as xGnP contents increased. E′ of the nanocomposite with only 7 wt% of xGnP was 2.5 times higher than that of the control LLDPE. Thermal expansion and the coefficient of thermal expansion of xGnP‐loaded composites were much lower than those of the control LLDPE in the range of 45–80°C (299.8 × 10−6/°C) and 85–100°C (365.3 × 10−6/°C). Thermal stability of the composites was also affected by xGnP dispersion in LLDPE matrix. The xGnP‐LLDPE nanocomposites by counter‐rotating screw system showed higher thermal stability than ones by co‐rotating and modified‐co‐rotating system at 5 wt% and 12 wt% of xGnP. xGnP had a great effect on high thermal stability of xGnP‐LLDPE composites to be applied as tube and film for electrical materials. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Dispersion of multiwalled carbon nanotubes in thermoplastic elastomer gels: Morphological, rheological, and electrical properties
Authors: Paglicawan Marissa A. , Kim Jin Kuk , Bang Dae‐Suk 
Published: July 2010

AbstractAn investigation was reported here with an aim to prepare nanocomposite thermoplastic elastomer gels by dissolving polystyrene‐b‐poly(ethylene/butylene)‐b‐polystyrene (SEBS) triblock copolymer in selective hydrocarbon oils with the presence of multiwalled carbon nanotubes (MWCNTs). The properties related to morphology, viscoelasticity, electrical and mechanical properties, and thermal stability were explored and discussed. Dynamic rheological measurements of the resultant nanocomposite thermoplastic elastomer gels (NCTPEGs) confirmed that addition of MWCNTs affects the linear viscoelastic properties in which dynamic storage and loss moduli increase to some extent. At a temperature between 30°C and 40°C below the gel point the NCTPEGs have dynamic storage modulus greater than loss modulus (G′ and G″), thereby indicating that at room temperature a physical network is still present despite the addition of MWCNTs. The morphological properties revealed that MWCNTs were dispersed and exfoliated within the swollen TPE. The incorporation of small quantity of MWCNTs improved the thermal stability and mechanical properties of NCTPEGs. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Erodent size effect on the erosion of polyphenylene sulfide composite
Authors: Sinmazcelik Tamer , Sari Nejat Y. 
Published: July 2010

AbstractThe effect of erodent particle size on solid particle erosion of randomly oriented short glass fiber and mineral particle reinforced polyphenylene sulfide (PPS) was investigated. To examine the effect of erodent size on the erosion resistance of the PPS composite, aluminum oxide particles at three different sizes, namely, 300–425 μm, 150–212 μm, and 45–75 μm, were used. The erosion tests were performed at six different contact angles of 15°, 30°, 45°, 60°, 75°, and 90°, respectively. The results showed a strong relationship between the erodent particle size and erosion rates of PPS composite. Maximum erosion rate for the erodent particles with sizes of 45–75 μm and 150–212 μm occurred at contact angle of 30°, on the other hand maximum erosion rate for particles having 300–425 μm size occurred between 45° and 60°. The morphologies of eroded surfaces were characterized by the scanning electron microscopy (SEM). Possible erosion mechanisms were discussed. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Dielectric behavior characterization of a fibrous‐ZnO/PVDF nanocomposite
Authors: Dagdeviren Canan , Papila Melih 
Published: July 2010

AbstractThis study is focused on forming a fibrous‐zinc oxide/polyvinylidine fluoride (ZnO/PVDF) nanocomposite and characterizing its dielectric behavior. The nanocomposite is prepared in two steps. First, a network of nanoscale diameter ZnO fibers is produced by sintering electrospun PVA/Zinc Acetate fibers. Second, the ZnO fibrous nonwoven mat is sandwiched between two PVDF thermoplastic polymer films by hot‐press casting. Scanning electron microscope images of the nanocomposite show that hot‐press casting of the fibrous‐ZnO network breaks the network up into short fibers. The in‐plane distribution of the ZnO fillers (i.e., the short fibers) in the PVDF matrix appears to comply with that of the pristine ZnO fibers before hot‐pressing, indicating that the fillers remain well‐dispersed in the polymer matrix. To the authors' knowledge, the work reported herein is the first demonstration of the use of electrospinning to secure the dispersion and distribution of a network of inorganic fillers. Moreover, processing a fibrous‐ZnO/PVDF flexible composite as described in this report would facilitate material handling and enable dielectric property measurement, in contrast to that on a fibrous mat of pure ZnO. Because of the high surface area of the short ZnO fibers and their polycrystalline structure, interfacial polarization is pronounced in the nanocomposite film. The dielectric constant is enhanced significantly‐up to a factor of 10 at low frequencies compared to the dielectric constant of constituent materials (both bulk ZnO and PVDF), and up to a factor of two compared to a bulk‐ZnO/PVDF composite. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Mechanisms of fracture in filled thermosetting resins
Authors: Brown Stephen K. 
Published: July 2010

AbstractFracture properties of a wide range of filled unsaturated polyester resin composites have been investigated with respect to filler size, shape, loading and adhesion to the matrix resin. Mechanisms are proposed for the fracture behaviors found, based on geometrical considerations of interacting filler particles and stress concentrations which result from them.
The refraction correction for the Fica 50 type of light scattering photometer
Authors: Suzuki Hidematsu , Muraoka Yoichior , Inagaki Hiroshi 
Published: July 2010

AbstractThe factor for the refraction correction was considered for the Fica 50 type of light scattering photometer, in which the scattered light is twice refracted before reaching the detector. The correction factor was first calculated after Hermans and Levinson, which elucidated that the factor is just the same as for the Brice type of photometer, and a vat liquid has no further effects on the final form of the correction factor. This result was examined and found to be practically applicable to a Fica 50 photometer by measuring the scattering intensities of several liquids and the RAPRA PS2 standard polystyrene in solvents of varying refractive index.
Highly conjugated organic polymers as heterogenous catalysts (II): The interaction of nitrogen monoxide and pyrolysed polyacrylonitrile
Authors: Cooper David R. , Tighe Brian J. 
Published: July 2010

AbstractThe interaction of nitrogen monoxide (nitric oxide, NO) with pyrolysed polyacrylonitrile (PANP) has been examined together with the feasibility of the use of PANP based catalysts for the removal of small quantities of NO from the exhaust systems of internal combustion engines. Kinetic studies indicated that PANP was capable of interacting with and removing NO from an inert carrier gas and that the initial specificity of this interaction was little affected by hydrogen, hydrocarbons, carbon monixide or oxygen, the initial rates of removal being appreciably higher than those obtainable with conventional inorganic catalysts or graphitised carbon. The activation energy and kinetic features of the reaction suggested that the interaction involved the odd electron nature of NO and the free spin generated at the polymer surface. Once adsorbed the nitric oxide decomposes to form dinitrogen oxide (N2O) which is further reduced to nitrogen with concurrent assimilation and rearrangement of oxygen within the polymer structure. As a result the PANP gradually loses its capacity to adsorb and decompose NO. In addition, it appears that the structural features which promote the oxidative instability of PANP also govern its NO removal ability. Consequently, the lifetime and therefore practical utility of these systems is governed by the limits of oxidative stability and catalytic capacity.
The Copolymerisation of Vinyl Chloride with Allyl Chloride
Authors: Lewis John , Okieimen Felix E. , Park Geoffrey S. 
Published: July 2010

AbstractThe kinetics of copolymerisation of vinyl chloride with allyl chloride in chlorobenzene and in dichloroethane solvent have been studied by a dilatometric method. The compositon of the copolymers was determined by reduction with tributyltin hydride followed by infrared examination. Molecular weights obtained by g.p.c. enable as estimate of the transfer constant for degradative transfer to allyl chloride to be made for both the chlorobenzene and dichloroethane solvent systems. The results show that allyl chloride retards vinyl chloride polymerisation by degradative transfer and that the resulting radicals combine with the growing polymer chains. The dependence of copolymer composition on the composition of the monomer feed reveals that one of the pair of reactivity ratios associated with this reaction in either solvent has a negative value.
Catalyst Systems in Anionic Copolymerisations
Authors: Richards David H. 
Published: July 2010

AbstractThe paper considers three areas of current interest in anionic polymerisation. Firstly, the factors governing the efficiencies of initiation of anionic electron transfer catalysts are discussed, and the differences between the initiation mechanism of this class of catalysts and that of alkali metals are highlighted. Secondly, the problems relating to the synthesis of telechelic polydienes of high 1,4 content by an anionic technique are examined in relation to the contradictory claims of recent authors. Finally an account is given of the present position in developing transformation reactions to prepare novel block copolymers.
X‐Ray Powder Diffraction Studies of Hydrocerussite (Basic Lead Carbonate) as a Stabiliser in Plasticised Polyvinyl Chloride
Authors: Michell E. W. John , Ng Kok Y. 
Published: July 2010

AbstractStrips from a plasticised PVC blend containing pure hydrocerussite, 2PbCO3.Pb(OH)2, as stabiliser were heated under nitrogen at 180°C for various periods up to the time when hydrogen chloride (HC1) was liberated and could be detected externally by Congo‐red indicator paper. Evolved carbon dioxide (CO2) was measured and crystalline phases in the heated samples were studied by X‐ray powder diffraction (X.R.P.D.).Qualitative X.R.P.D. showed that the hydrocerussite reacted to form the uncharacterised basic lead chloride X (B.L.C.X.) and normal lead chloride, PbCl2, in sequence. Quantitative X.R.P.D. showed that the hydrocerussite reacted according to first order kinetics, and the rate constant and half‐life were confirmed by data from the CO2 measurements. These results accord with previous studies using the other basic lead carbonate ‘plumbonacrite’, 6PbCO3.3Pb(OH)2.PbO, as stabiliser. However, the rates of stabiliser reaction differed and, surprisingly, efficient stabilisation continued long after the hydrocerussite had all reacted in the present experiments, whereas stabilisation failed soon after the plumbonacrite had all reacted previously.These findings are interpreted on the basis of a free‐radical exchange and temporary esterification mechanism in which mobile lead salts of organic acids are regenerated as the active stabilising intermediates, and which is believed to retard the PVC thermal decomposition (preventing the formation of HCl). This is called ‘true stabilisation’. The popular idea that basic lead stabilisers merely behave as scavengers for HCl from the hot polymer is rejected because this cannot be reconciled with the fact that stabilisation continued in the absence of hydrocerussite, or with the observed first order kinetics of stabiliser reaction. These studies are briefly related to commercial PVC processing.
Rheololgy of Mesomorphic Solutions of Cellulose
Authors: Navard Patrick , Haudin Jean‐Marc 
Published: July 2010

AbstractSolutions of cellulose were prepared with liquid crystal phases by mixing cellulose, water and N‐methylmorpholine N‐oxide under appropriate conditions of concentration and temperature. Their rheological behaviour was studied using capillary rheometry. For each solution, flow curves were plotted over a temperature range of 70‐‐120°C, and a shear rate range of 1‐‐500 sec−1.Considerable agreement was found between the rheological and optical characterisations of the anisotropic‐isotropic transition temperature T*. The variations of the strain rate sensitivity parameter m were studied over a large temperature range and particularly around T*. These results, new for cellulose solutions, provide some valuable information about the rheology of anisotropic polymer fluids.
Aspects of Vinyl Chloride Suspension Polymerisation
Authors: Sanderson Albert K. 
Published: July 2010

AbstractSome observations on the formation and growth of PVC granules during polymerisation are described, particularly with reference to granule morphology. The physical structure of the final granule is very dependent on polymerisation variables and of these, the influence of reactor agitation, temperature of polymerisation and protective colloid are briefly discussed.