bluuebunny/crossref_metadata_2025 huggingface dataset:
Gel as a Definitive Property in GR-S Technology
Authors: White L. M. , Ebers E. S. , Shriver G. E. , Breck S.
Published: February 2011

1. Of the gel fraction that may occur in GR-S, only that portion which has low swelling volume in benzene—tight (B) gel—markedly affects processing behavior and quality of product. 2. As the proportion of tight (B) gel increases, mixing operations become more difficult, and the quality of the final vulcanizate is lowered; specifically, decreased tensile strength, increased modulus, and decreased cut-growth resistance result. Where maximum quality is desired, processing conditions which favor the formation of tight gel should be avoided. 3. Conversely, appreciable amounts of tight (B) gel aid the processing operations of calendering and extrusion by reducing shrinkage and roughness. Where ease of processing is paramount and quality defects can be tolerated, heat-plasticization cycles which favor gel formation may be used to advantage. 4. To account for the observed effects of tight gel, the theory is advanced that fillers cannot enter this gel portion. This explanation is supported by a limited amount of direct evidence. 5. Heat-plasticization studies of GR-S at 320° F in the presence and absence of carbon black indicate that the black reduces the tendency to gel formation. For short heat treatments, common to many factory processes, the effect has no significance. For extended heat plasticization, incorporation of the black first may be either advantageous or detrimental, depending on whether maximum quality or ease of processing is the end objective.
The Effects of Proöxygenic Substances on Reclaimed Rubber
Authors: Haehl A.
Published: February 2011

It might at first be assumed that antioxygenic compounds originally present in scrap rubber used in the manufacture of the reclaimed rubber would be sufficient to explain the extraordinary resistance of the reclaimed rubber to the action of proöxygenic compounds. It is, however, highly improbable that these antioxygenic compounds survive caustic soda treatment at 190° C. On the other hand, a crude-rubber mixture, even when protected by an antioxygenic compound, never shows such great resistance to proöxygenic compounds as that shown by the reclaimed-rubber vulcanizates described in the present work. It seems probable, therefore, that this insensitivity of reclaimed rubber to proöxygenic compounds, both during plasticization and during aging after vulcanization, is in some way connected with the actual chemical structure of the reclaimed rubber itself.
The Morphology of Rubber Latex Particles. A Critical Review
Authors: Hauser Ernst A.
Published: February 2011

The morphology of the hydrocarbon particles of latices obtained from several rubber producing plants has in recent years again been the subject of studies applying the most modern tools of research. Lucas used for his studies an ultraviolet light microscope and later ultramicrocinematography. Quite recently Hendricks, Wildman, and McMurdie applied electron microscopy for the first time for this purpose. Since some of the deductions in regard to the form and structure of latex particles which have been drawn from these studies differ in several respects from conclusions based on micrugic and ultramicroscopic studies, some of which were reported twenty years ago, it seems advisable to clarify the picture. Such clarification is most important at present, because a better knowledge of the morphology of natural and synthetic rubber latex particles might offer a valuable aid in explaining some of the differences in the properties of these hydrocarbon polymers, which are not readily explainable on the basis of differences in chemical composition alone.
Vulcanization of Rubber with Synthetic Resins
Authors: Wildschut A. J.
Published: February 2011

Natural and synthetic rubber can be vulcanized with several vulcanizing agents other than sulfur, though sulfur and sulfur compounds are the only agents of practical value. A combination of rubber and synthetic resin can be successful only when chemical bonds are formed. It has been found that this is the case with certain synthetic resins, and that natural and synthetic rubber can be vulcanized with these resins, without adding any other agent or filler, in much the same way as with sulfur. An example of these resins is the resol from pentaphene (p-t-amylphenol) and formaldehyde. Data are given for the technical properties of rubber-resin vulcanizates. Catalysis or a similar effect is produced by magnesium oxide, which increases the tensile strength, while hexamethylenetetramine prevents the reaction. Balata can be vulcanized with the same synthetic resins as rubber; with gutta-percha the effect of heating with rubber-vulcanizing resins is the same as with sulfur. The probable configuration of the rubber-resin vulcanizates consists of two systems of entangled thread-molecules, which are interlinked at a limited number of points by primary valence bonds.
A New Material: Anhydride Rubber. I
Authors: Le Bras Jean
Published: February 2011

In earlier work on the action of various unsaturated compounds on rubber, Compagnon and the present author described briefly a new reaction of maleic anhydride. It should be added, as a matter of record, that the reaction of maleic anhydride and rubber had already been studied by Bacon and Farmer, who, in a very interesting work, described a process for obtaining addition products of rubber and maleic anhydride. It is well, therefore, first of all to describe the principle of their work and the results which were obtained. The first observation made by Bacon and Farmer was that when a toluene solution of milled crude rubber is heated for several hours at about 100° C with maleic anhydride in the presence of benzoyl peroxide, which acts as a catalyst, a definite reaction takes place. The reaction product can be precipitated by alcohol, and can then be recovered in the form of a white or pale yellow resin which does not have any of the elastic properties of rubber. In a more extensive investigation of the reaction, where the experimental conditions were varied, e.g., the proportions of benzoyl peroxide and of maleic anhydride, nature of the solvent, concentration of the solution, and time and temperature of heating, Bacon and Farmer succeeded in obtaining a true series of addition products, whose properties changed progressively with the proportion of chemically combined maleic anhydride. With increase in the proportion of maleic anhydride, there was a gradual transition from products which were still somewhat rubbery to fibrous products, and finally to hard brittle resins which contained more than one-third by weight of chemically combined maleic anhydride and which had none of the physical properties characteristic of rubber. As might be expected, the solubilities likewise changed progressively from products which were soluble in rubber solvents to those which were soluble in solvents for maleic anhydride; e.g., some of the derivatives were soluble in boiling ethyl alcohol.
Anhydride Rubber. II. Production and Vulcanization
Authors: Compagnon Patrice , Bonnet Odette
Published: February 2011

In the first part of this work, Le Bras described the interesting characteristics of the product obtained by combination, on a mill, of rubber and maleic anhydride, and he called attention to the useful potentialities of this reaction in connection with the reaction described previously by Bacon and Farmer. It is intended in the present part of the work to give, first of all, some practical information on the way that the reaction can be carried out. But, since the new modified rubber must be vulcanized to be of any practical value, and since, as might be expected, the conditions of vulcanization are not the same as for ordinary rubber, the means which have been found for carrying out this operation are described. It is obvious that, because of the many accelerators and combinations of accelerators which might have been tried, there was no pretention of obtaining ideal results in this first work ; however, since the results which have been obtained so far are sufficiently promising to be of practical value, a description of the method of vulcanization which has already been developed should be useful as a basis for further work by those who may be interested in these reactions.
New Method for Determining the Filler Content of Vulcanized Rubber
Authors: Hublin R. A.
Published: February 2011

The new reagent, o-nitroanisol makes it possible to shorten to a considerable extent the determination of the total filler content of vulcanized rubber, and to increase the precision of the determination. In addition, the procedure is carried out more easily than are the older classic procedures. It would seem desirable, therefore, to use this more convenient solution method of determining filler content in many cases in place of calcination methods, which, though rapid, are very inaccurate, and in place of the conventional solution methods, which are so inconvenient.
Comparative Study of Plasma-Thiophene and -Acetylene Coated Silica in SBR and EPDM Reinforcement
Authors: Tiwari M. , Datta R. N. , Talma A. G. , Noordermeer J. W. M. , Dierkes W. K. , van Ooij W. J.
Published: February 2011

The surface characteristics of silica were modified by plasma-thiophene and -acetylene film deposition. The plasma-coated fillers were blended with S-SBR and EPDM, and their influence on the final vulcanizate properties was compared with untreated silica and silanized silica. The change in the surface energy of plasma-acetylene (PA) and thiophene- (PTh) coated silica was characterized by immersion tests in liquids of various surface tension, water penetration measurements, Thermo Gravimetric Analysis (TGA) and Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). All techniques gave evidence of a polymeric PA- and PTh-film deposition on the surface of silica. The properties of S-SBR and EPDM, filled with untreated, PA-, PTh- and silane-treated silica, were investigated by measurement of the Payne effect, bound rubber content and weight loss related to bound rubber, the reinforcement parameter, relative ranking of cross-link density and mechanical properties. The results show a lower degree of flocculation for PTh-silica filled EPDM due to a better match of the surface energies compared to untreated and PA-treated silica. EPDM filled with plasma-thiophene coated silica shows the lowest reinforcement parameter value, thus improved dispersion compared to untreated, silane-treated and plasma-acetylene silica. However, PA-silica filled EPDM shows better mechanical properties compared to untreated and plasma-thiophene coated silica. The PTh-silica filled S-SBR shows a higher bound rubber content, which results in better mechanical properties of the S-SBR compound compared to the one with PA-coated silica. The overall results show that the compatibility and interaction of silica with different rubbers can be controlled by tailoring the surface energy of the filler by plasma-polymerization. The different functionalities on the silica surface result in different levels of compatibility and interaction, as well as final vulcanizates properties.
Degradation of the Rubber Network during Dynamic Vulcanization of EPDM/PP Blends Using Phenolic Resol
Authors: Antunes C. F. , Machado A. V. , van Duin M.
Published: February 2011

Physical blends and thermoplastic vulcanizates (TPVs) based on EPDM and PP were prepared in a batch mixer. Dynamic vulcanization of TPVs using resol/SnCl2 was studied as a function of time. Static and dynamic vulcanization of EPDM in the absence of PP were also studied. Crosslinking of EPDM in the absence of PP is more efficient via static than dynamic vulcanization. For EPDM/PP-based TPVs the extent of crosslinking reaction versus time decreases as the amount of EPDM increases. Degradation of the EPDM network occurs during dynamic vulcanization, due to the combined action of shearing and high temperature, and increases as EPDM becomes more and more the continuous phase.
AFM Studies on Silica Dispersion in EPDM Rubber
Authors: Natchimuthu N.
Published: February 2011

EPDM rubber formulations filled with precipitated silica and cross-linked by peroxide vulcanization have been investigated with the objective of realizing better processing characteristics and vulcanizate properties. Dispersion of silica in EPDM rubber in the presence of conventional coupling agents and in the presence of an epoxy resin has been investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM results of EPDM rubber compounds containing silica fillers in the presence of the epoxy resin have exhibited improved silica dispersion in terms of scanned height. The latter has been found to be in the range of 0–100 nm for EPDM rubber—silica systems with epoxy resin, while in the absence of the resin, scanned height has been found to be in the range of 0–700 nm. The significant reduction in scanned height in the presence of epoxy resin has been attributed to the reduction in surface roughness which is an indication for good dispersion of silica in the rubber. Morphological studies using SEM, mechanical properties, and Mooney-Rivlin constants all have shown significant improvement in performance properties of EPDM rubber—silica compounds containing epoxy resin and vulcanized with dicumyl peroxide.
Trouser Tearing of a Model Natural Rubber Tire Belt Vulcanizate. Part 1: Effect of Rate of Tearing
Authors: Hamed G. R. , Hiza S.
Published: February 2011

A model natural rubber tire belt vulcanizate (50 phr N330; 5 phr S; 0.75 phr DCBS accelerator) was torn using a trouser tear test piece that had legs 6 mm thick and an intended tear path about 0.8 mm thick. Tearing at 500 mm/min resulted in three distinct tear types. Two of the tear types gave high tearing forces, were stick—slip, and involved deep tearing into the legs (“chunk-out” and “knotty”). In the third, the tear remained in the thin path, alternated between legs (“sawtooth”), and was more-or-less steady. Cracking into the legs sometimes occurs and other times not. This variation appears to be inherent. It is attributed to variations in strain-induced crystallinity at high rates of strain. At a slower test rate of 5 mm/min, only knotty tearing was found. At 5 mm/min, there appears to be ample time for crystallites to develop well, and knotty tearing is always seen.
Trouser Tearing of a Model Natural Rubber Tire Belt Vulcanizate. Part 2: A Brief Note on the Effect of Cure Time
Authors: Hamed G. R. , Hiza S.
Published: February 2011

The effect of test rate on the tearing of a model natural rubber tire belt vulcanizate was previously discussed. We now discuss specimens of the same vulcanizate, cured for various times at 160 °C, which were torn apart. Prior to reversion, tear strength was high and knotty, but specimens tore rather easily when they were cured longer than the time for the onset of reversion.
Bipolar Tetraarylsilanes as Universal Hosts for Blue, Green, Orange, and White Electrophosphorescence with High Efficiency and Low Efficiency Roll‐Off
Authors: Gong Shaolong , Chen Yonghua , Luo Jiajia , Yang Chuluo , Zhong Cheng , Qin Jingui , Ma Dongge
Published: February 2011

A series of tetraarylsilane compounds, namely p‐BISiTPA (1), m‐BISiTPA (2), p‐OXDSiTPA (3), m‐OXDSiTPA (4), are designed and synthesized by incorporating electron‐donating arylamine and electron‐accepting benzimidazole or oxadiazole into one molecule via a silicon‐bridge linkage mode. Their thermal, photophysical and electrochemical properties can be finely tuned through the different groups and linking topologies. The para‐disposition compounds 1 and 3 display higher glass transition temperatures, slightly lower HOMO levels and triplet energies than their meta‐disposition isomers 2 and 4, respectively. The silicon‐interrupted conjugation of the electron‐donating and electron‐accepting segments gives these materials the following advantages: i) relative high triplet energies in the range of 2.69–2.73 eV; ii) HOMO/LUMO levels of the compounds mainly depend on the electron‐donating and electron‐accepting groups, respectively; iii) bipolar transporting feature as indicated by hole‐only and electron‐only devices. These advantages make these materials ideal universal hosts for multicolor phosphorescent OLEDs. 1 and 3 have been demonstrated as universal hosts for blue, green, orange and white electrophosphorescence, exhibiting high efficiencies and low efficiency roll‐off. For example, the devices hosted by 1 achieve maximum external quantum efficiencies of 16.1% for blue, 22.7% for green, 20.5% for orange, and 19.1% for white electrophosphorescence. Furthermore, the external quantum efficiencies are still as high as 14.2% for blue, 22.4% for green, 18.9% for orange, and 17.4% for white electrophosphorescence at a high luminance of 1000 cd m−2. The two‐color, all‐phosphor white device hosted by 3 acquires a maximum current efficiency of 51.4 cd A−1, and a maximum power efficiency of 51.9 lm W−1. These values are among the highest for single emitting layer white PhOLEDs reported till now.
Energetics during reproduction: A doubly labeled water study of lactating baboons
Authors: Rosetta L. , Lee P.C. , Garcia C.
Published: February 2011

Understanding the costs and regulation of reproduction in primates requires understanding the separate but linked effects of energy availability and total energy expenditure (TEE). We compared variation in TEE and energy intake (EI) between two periods, early lactation and after the resumption of sexual cycling, for eight females from two groups of normally reproducing colony‐living baboons (Papio h. anubis). Total energy expenditure was assessed using the doubly labeled water method. TEE was correlated with maternal mass both during early lactation and after the resumption of cycling. TEE after the resumption of cycling was positively related to infant growth rates; mothers with rapidly growing infants had higher energy expenditure. TEE was however unrelated to maternal rank and only weakly associated with reproductive parameters such as delay to conception. EI in early lactation was related to infant mass and interbirth intervals, but unrelated to infant growth or reproductive parameters once cycling had resumed. Energy availability (EA; the difference between intake and expenditure) differed significantly between subordinate and dominant females during early lactation, was highly variable among individuals as a function of body composition, and is suggested to follow a nonlinear relationship as a complex function of social status, lactation stage, infant growth, and female fertility. Thus, as a consequence of reduced energy availability, subordinate females in this captive context may experience reproductive delays even though the total energy expenditure after the return of cycling was similar between high and low ranking females. Am J Phys Anthropol, 2011. © 2011 Wiley‐Liss, Inc.
Improving stable isotopic interpretations made from human hair through reduction of growth cycle error
Authors: Williams L.J. , White C.D. , Longstaffe F.J.
Published: February 2011

A recent trend in stable isotopic analysis involves the reconstruction of short‐term variations in diet using hair segments. However, bulk hair samples typically contain a growth cycle error, which may conceal or confound the most recently incorporated isotopic information. It is assumed that, at any given time, ∼85–90% of scalp hairs are actively growing, while the remaining 10–15% have transitioned into a resting or inactive phase, which lasts up to 4 months before hairs are shed. This study uses growth phase to determine the effects of age, sex, and health status on carbon and nitrogen isotopic ratios of hair analyzed in sequential segments. For this study, we selected archaeological hair samples from 10 individuals from Dakhleh Oasis, Egypt. Isotopic analyses of actively growing hair segments were compared to those for mixed growth phase segments from each individual. These data demonstrate the presence of growth cycle error and show that an understanding of structural–functional relationships is essential for interpreting normal versus pathological changes in hair follicle and fiber production. In situations where diet change and mobility produce variations in an individual's isotopic composition, elimination of positional–temporal error in sequential segment hair analyses can facilitate greater understanding of intraindividual metabolic reactions and changes in hair growth cycles. Phase identification may aid in determining the presence of pathological conditions in individuals, especially in those lacking skeletal indications, and provide a more precise estimation of seasonal dietary patterns, access to changing food resources, and metabolic equilibration to a new locality. Am J Phys Anthropol, 2011. © 2011 Wiley‐Liss, Inc.
CFD investigation of new helical ribbon mixers bottom shapes to improve pumping
Authors: Sanjuan‐Galindo Rene , Heniche Mourad , Ascanio Gabriel , Tanguy Philippe A.
Published: February 2011

It is well known that helical ribbon (HR) impellers exhibit poor bottom pumping properties. Three different HR impeller geometries, varying in their bottom design, are compared in terms of their mixing performance. Particular emphasis is given to the improvement of pumping capabilities. The selected bottom geometries were a standard bottom termination, an anchor‐type termination and a paddle‐type termination. The investigation was based on the use of 3D finite‐element simulation to assess the hydrodynamics and mixing performance using various distributive and dispersive criteria. Analysis of Poincaré maps showed that an HR with a paddle‐type termination operating in a down‐pumping mode offered the best performance. Copyright © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.
Experimental design study on the combined effect of citrate–pyrophosphate and citrate–aluminum on calcium oxalate monohydrate crystallization
Authors: Djelloul A. , Driouch A. , Taleb F. , Kaid‐Omar Z. , Semmoud A. , Addou A.
Published: February 2011

Our objective is to study the interaction between calcium oxalate (CaOx) low molecular weight inhibitors such as aluminum and pyrophosphate and to analyze their effect on nucleation and crystal growth while combined two by two to citrate. At physiological concentrations, CaOx crystallization, with or without inhibitors, was studied by spectrophotometry at 620 nm. All experiments were undergone at 37 °C. A mathematical model was used in order to optimize the number of experiments. Results showed that the inhibition power increases with inhibitor concentration when the molecule is tested alone. We obtained an important inhibition reaching a maximum of 93.9% for a citrate concentration of 2.5 mM, an inhibition of 87.8% for an aluminum concentration of 0.528 mM and an inhibition of only 34% for a 0.2 mM concentration of pyrophosphate. Citrate and aluminum act on nucleation, crystal growth and aggregation, while pyrophosphate acts weakly on crystal growth. The induction time is more or less constant. Results show that at any combined citrate pyrophosphate concentration, the effects are higher than those obtained for the inhibitors taken alone. The induction time for the combined inhibitors is more important than for a single inhibitor, thus triggering delay in nucleation. The citrate–pyrophosphate combination gives a synergetic effect at any used concentrations, whereas the effect of citrate–aluminum combination depends of the used concentrations of the two inhibitors. The results allow to quantify the contribution of inhibitors in the overall inhibition. The mathematical models fitted the experimental results well with a minimum of trials. © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.
Effects of the compatibilizer structural parameters on microstructural formation in ethylene–propylene–diene monomer rubber/ethylene–propylene–diene monomer rubber‐g‐maleic anhydride/organoclay nanocomposites
Authors: Mohammadpour Y. , Katbab A. A.
Published: February 2011

Nanocomposite vulcanizates based on ethylene–propylene–diene monomer rubber (EPDM) and organically modified montmorillonite with improved mechanical and barrier properties were prepared via a melt‐mixing process in the presence of maleic anhydride grafted ethylene–propylene–diene monomer rubber (EPDM‐g‐MAH) as an interfacial compatibilizer. The effects of the EPDM Mooney viscosity as the matrix and also the compatibilizer molecular weight and its maleation degree on the developed microstructure were also studied. The annealing of the vulcanized nanocomposites based on a low‐Mooney‐viscosity EPDM matrix and low‐Mooney‐viscosity EPDM‐g‐MAH enhanced the flocculation of the dispersed clay platelets; this implied that the flocculated structure for the clay nanolayers was more thermodynamically preferred in these nanocomposites. This was verified by the decrease in the oxygen permeability of the nanocomposite vulcanizates with increasing annealing time. The tendency of the clay nanosilicate layers to flocculate within the matrix of EPDM was found to be influenced by the clay volume fraction, the maleation degree, and also, the Mooney viscosity of the compatibilizer. Interfacially compatibilized nanocomposites based on high‐molecular‐weight EPDM exhibited a more disordered dispersion of the clay nanolayers, with a broadened relaxation time spectra; this was attributed to the higher shearing subjected to the mix during the melt‐blending process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Inhibition of Notch signaling prevents experimental fibrosis and induces regression of established fibrosis
Authors: Dees Clara , Zerr Pawel , Tomcik Michal , Beyer Christian , Horn Angelika , Akhmetshina Alfiya , Palumbo Katrin , Reich Nicole , Zwerina Jochen , Sticherling Michael , Mattson Mark P. , Distler Oliver , Schett Georg , Distler Jörg H. W.
Published: February 2011

Objective

Tissue fibrosis caused by pathologic activation of fibroblasts with increased synthesis of extracellular matrix components is a major hallmark of systemic sclerosis (SSc). Notch signaling regulates tissue differentiation, and abnormal activation of Notch signaling has been implicated in the pathogenesis of various malignancies. The present study was undertaken to investigate the role of Notch signaling in SSc and to evaluate the therapeutic potential of Notch inhibition for the treatment of fibrosis.

Methods

Activation of the Notch pathways was analyzed by staining for the Notch intracellular domain (NICD) and quantification of levels of HES‐1 messenger RNA. In the mouse model of bleomycin‐induced dermal fibrosis and in tight skin 1 mice, Notch signaling was inhibited by the γ‐secretase inhibitor DAPT and by overexpression of a Notch‐1 antisense construct.

Results

Notch signaling was activated in SSc in vivo, with accumulation of the NICD and increased transcription of the target gene HES‐1. Overexpression of a Notch antisense construct prevented bleomycin‐induced fibrosis and hypodermal thickening in tight skin 1 mice. Potent antifibrotic effects were also obtained with DAPT treatment. In addition to prevention of fibrosis, targeting of Notch signaling resulted in almost complete regression of established experimental fibrosis.

Conclusion

The present results demonstrate that pharmacologic as well as genetic inhibition of Notch signaling exerts potent antifibrotic effects in different murine models of SSc. These findings might have direct translational implications because different inhibitors of the γ‐secretase complex are available and have yielded promising results in cancer trials.
Funktionelle Akustik — Die Nachhall‐Charakteristik des Raumes als Basis für seine Nutzbarkeit.
Authors: Fuchs Helmut V.
Published: February 2011

Im aktuellen Baugeschehen spielt der Lärmschutz gemäß DIN 4109 und VDI 4100 bereichsweise eine wichtige Rolle. Dagegen wird die Raumakustik, auch nach dem Erscheinen der neuen DIN 18041, noch immer sträflich unterschätzt und oft schlecht behandelt. Das trifft für Räume jeder Größe und Nutzungsart gleichermaßen zu. Erfahrungen aus Hunderten von Neubauten, Restaurierungen und Sanierungen, bei denen es um den Schallschutz ebenso wie um die bestimmungsgemäße Nutzung für Sprache und Musik ging, legen es nahe, die Nachhall‐Charakteristik der Räume neu in den Blickpunkt der Planer und Berater zu rücken. In dieser Beitragsserie wird auf einige Fehleinschätzungen und Missstände aufmerksam gemacht, die insbesondere die Behandlung des Bassbereichs betreffen. An konkreten praktischen Beispielen wird demonstriert, wie man dem raumakustischen Design neue funktionelle Möglichkeiten erschließen kann, wenn man mit der richtigen Bedämpfung der tiefen Frequenzen generell für mehr akustische Transparenz und Klarheit sorgt.

Functional acoustics — The reverberation characteristic as a basis for room quality. Noise control according to German standards DIN 4109 and VDI 4100 occasionally plays an important role. Architectural acoustics, however, are still deplorably underrated and ill‐treated, even after the new DIN 18041 has been issued. This holds for enclosures of any size and uses. Experiences from hundreds of new buildings, restorations and adjustments which dealt with acoustic comfort as well as functional value for speech and music suggest that designers and consultants should pay new and more attention to the reverberation characteristics of the rooms. This series will focus on misconceptions and nuisances concerning the treatment of the bass spectrum. Concrete practical examples will help to demonstrate, how one may create new design options by enabling more acoustic transparency and clarity through an adequate damping of the low frequencies.
Polystyrol‐Extruderschaum mit verbesserten wärmetechnischen Eigenschaften — Entwicklung, Prüfung und Anwendung
Authors: Bunge Friedhelm , Merkel Holger
Published: February 2011

Ein neuer Wärmedämmstoff aus extrudiertem Polystyrol‐Hartschaum (XPS) mit geringerer Wärmeleitfähigkeit wurde entwickelt, um die erhöhten Anforderungen an einen dauerhaften Wärmeschutz von Gebäuden einfacher und mit geringerem Materialaufwand zu erfüllen. Die bewährten mechanischen und hygrothermischen Eigenschaften von XPS‐Dämmstoffen werden beibehalten. Die erste Produkt‐Generation ist insbesondere für die außenliegende Wärmedämmung von erdberührten Wänden und Böden sowie für die Kerndämmung von zweischaligen Wänden entwickelt worden. Das verwendete CO2‐Schäumverfahren entspricht den bestehenden Anforderungen an die Nachhaltigkeit von Bauprodukten.

Development, testing and application of extruded polystyrene foam (XPS) insulation with improved thermal properties. Improved extruded polystyrene foam (XPS) insulation with lower thermal conductivity has been developed. This enables meeting the increased requirements for sustainable building insulation with better material efficiency. The proven mechanical and hygro‐thermal properties of XPS insulation are maintained. This first product generation has been developed primarily for external perimeter insulation of basement walls and floors as well as for the insulation of cavity walls. The CO2 foaming technology meets the sustainability requirements for building products.
Partitioned partial least squares regression with application to a batch fermentation process
Authors: Andersen Stina W. , Runger George C.
Published: February 2011

The performance of Partial Least Squares regression (PLS) in predicting the output with multivariate cross‐ and autocorrelated data is studied. With many correlated predictors of varying importance PLS does not always predict well and we propose a modified algorithm, Partitioned Partial Least Squares (PPLS). In PPLS the predictors are partitioned into smaller subgroups and the important subgroups with high prediction power are identified. Finally, regular PLS analysis using only those subgroups is performed. The proposed Partitioned PLS (PPLS) algorithm is used in the analysis of data from a real pharmaceutical batch fermentation process for which the process variables follow certain profiles during a specific fermentation period. We observed that PPLS leads to a more accurate prediction of the yield of the fermentation process and an easier interpretation, since fewer predictors are used in the final PLS prediction. In the application important issues such as alignment of the profiles from one batch to another and standardization of the predictors are also addressed. For instance, in PPLS noise magnification due to standardization does not seem to create problems as it might in regular PLS. Finally, PPLS is compared to several recently proposed functional PLS and PCR methods and a genetic algorithm for variable selection. More specifically for a couple of publicly available data sets with near infrared spectra it is shown that overall PPLS has lower cross‐validated error than PLS, PCR and the functional modifications hereof, and is similar in performance to a more complex genetic algorithm. Copyright © 2011 John Wiley & Sons, Ltd.
Convenient and Efficient FRET Platform Featuring a Rigid Biphenyl Spacer between Rhodamine and BODIPY: Transformation of ‘Turn‐On’ Sensors into Ratiometric Ones with Dual Emission
Authors: Yu Haibo , Xiao Yi , Guo Haiying , Qian Xuhong
Published: February 2011

We have connected a borondipyrromethene (BODIPY) donor to the 5′ position of a tetramethylrhodamine (TMR) acceptor to form a high efficiency (over 99 %) intramolecular fluorescence resonance energy transfer (FRET) cassette, BODIPY–rhodamine platform (BRP). While the good spectral overlap between the emission of BODIPY and the absorption of TMR was one favorable factor, another feature of this FRET system was the rigid and short biphenyl spacer that favored efficient through‐bond energy transfer. More importantly, in this system, the 2′‐carboxyl group of the rhodamine unit was preserved for the further modifications, which was as convenient as those carbonyl groups on the original rhodamines without connection to donors. For this reason, BRP is clearly differentiated from the previous ratiometric sensors based on donor rhodamine systems. To illustrate its value as a versatile platform, we introduced typical Hg2+ receptors into BRP, through convenient one‐pot reactions on the 2′‐carboxyl group, and successfully developed two ratiometric sensors, BRP‐1 and BRP‐2, with different spirocyclic receptors that recognized Hg2+ on different reaction mechanisms. Upon excitation at a single wavelength (488 nm), at which only BODIPY absorbed, both of the FRET sensors exhibited clear Hg2+‐induced changes in the intensity ratio of the two strong emission bands of BODIPY and rhodamine. It should be noted that these ratiometric Hg2+ sensors exhibited excellent sensitivity and selectivity Hg2+, as well as pH insensitivity, which was similar to the corresponding ‘turn‐on’ rhodamine sensors. While both ratiometric probes were applicable for Hg2+ imaging in living cells, BRP‐1 exhibited higher sensitivity and faster responses than BRP‐2. Our investigation indicated that on a versatile platform, such as BRP, a large number of highly efficient ratiometric sensors for transition‐metal ions could be conveniently developed.
ChemInform Abstract: Enhanced Low‐Temperature Proton Conduction in Sr0.02La0.98NbO4‐δ by Scheelite Phase Retention.
Authors: Brandao A. D. , Antunes I. , Frade J. R. , Torre J. , Kharton V. V. , Fagg D. P.
Published: February 2011

Powders of Sr0.02La0.98Nb1‐xVx O4‐δ (x = 0.15—0.5) are prepared by solid state synthesis of stoichiometric mixtures of SrCO3, La2O3, Nb2O5, and V2O5 (1300 °C, 10 h).
Akt1 interacts with epidermal growth factor receptors and hedgehog signaling to increase stem/transit amplifying cells in the embryonic mouse cortex
Authors: Sinor‐Anderson Amy , Lillien Laura
Published: February 2011

A subset of precursors in the embryonic mouse cortex and in neurospheres expresses a higher level of the serine/threonine kinase Akt1 than neighboring precursors. We reported previously that the functional significance of high Akt1 expression was enhanced Akt1 activity, resulting in an increase in survival, proliferation, and self‐renewal of multipotent stem/transit amplifying cells. Akt1 can interact with a number of signaling pathways, but the extrinsic factors that are required for specific effects of elevated Akt1 expression have not been identified. In this study we addressed the contributions of signaling via epidermal growth factor (EGF) and hedgehog (Hh) receptors. In EGF receptor‐null precursors or following transient inhibition of EGF receptor tyrosine kinase activity, elevating Akt1 by retroviral transduction could still increase survival and proliferation but could not increase self‐renewal. We also found that elevated Akt1 expression induced the expression of EGF receptors (EGFRs) in wild‐type precursors. Several extrinsic factors, including Shh, can induce EGFR expression by cortical precursors, and we found that elevating Akt1 allowed them to respond to a subthreshold concentration of Shh to induce EGFRs. In precursors that lack the Hh receptor smoothened, however, elevating Akt1 did not increase EGFR expression or self‐renewal, though it could still stimulate proliferation. These findings suggest that a subset of precursors in the embryonic cortex that express an elevated level of Akt1 can respond to lower concentrations of Shh than neighboring precursors, resulting in an increase in their expression of EGFRs. Signaling via EGFRs is required for their self‐renewal. © 2011 Wiley Periodicals, Inc. Develop Neurobiol 71: 759–771, 2011
Vision drives correlated activity without patterned spontaneous activity in developing Xenopus retina
Authors: Demas James A. , Payne Hannah , Cline Hollis T.
Published: February 2011

Developing amphibians need vision to avoid predators and locate food before visual system circuits fully mature. Xenopus tadpoles can respond to visual stimuli as soon as retinal ganglion cells (RGCs) innervate the brain, however, in mammals, chicks and turtles, RGCs reach their central targets many days, or even weeks, before their retinas are capable of vision. In the absence of vision, activity‐dependent refinement in these amniote species is mediated by waves of spontaneous activity that periodically spread across the retina, correlating the firing of action potentials in neighboring RGCs. Theory suggests that retinorecipient neurons in the brain use patterned RGC activity to sharpen the retinotopy first established by genetic cues. We find that in both wild type and albino Xenopus tadpoles, RGCs are spontaneously active at all stages of tadpole development studied, but their population activity never coalesces into waves. Even at the earliest stages recorded, visual stimulation dominates over spontaneous activity and can generate patterns of RGC activity similar to the locally correlated spontaneous activity observed in amniotes. In addition, we show that blocking AMPA and NMDA type glutamate receptors significantly decreases spontaneous activity in young Xenopus retina, but that blocking GABAA receptor blockers does not. Our findings indicate that vision drives correlated activity required for topographic map formation. They further suggest that developing retinal circuits in the two major subdivisions of tetrapods, amphibians and amniotes, evolved different strategies to supply appropriately patterned RGC activity to drive visual circuit refinement. © 2011 Wiley Periodicals, Inc. Develop Neurobiol 72: 537–546, 2012
High‐resolution electrophoretic simulations: Performance characteristics of one‐dimensional simulators
Authors: Mosher Richard A. , Breadmore Michael C. , Thormann Wolfgang
Published: February 2011

Three comprehensive one‐dimensional simulators were used on the same PC to simulate the dynamics of different electrophoretic configurations, including two migrating hybrid boundaries, an isotachophoretic boundary and the zone electrophoretic separation of ten monovalent anions. Two simulators, SIMUL5 and GENTRANS, use a uniform grid, while SPRESSO uses a dynamic adaptive grid. The simulators differ in the way components are handled. SIMUL5 and SPRESSO feature one equation for all components, whereas GENTRANS is based on the use of separate modules for the different types of monovalent components, a module for multivalent components and a module for proteins. The code for multivalent components is executed more slowly compared to those for monovalent components. Furthermore, with SIMUL5, the computational time interval becomes smaller when it is operated with a reduced calculation space that features moving borders, whereas GENTRANS offers the possibility of using data smoothing (removal of negative concentrations), which can avoid numerical oscillations and speed up a simulation. SPRESSO with its adaptive grid could be employed to simulate the same configurations with smaller numbers of grid points and thus is faster in certain but not all cases. The data reveal that simulations featuring a large number of monovalent components distributed such that a high mesh is required throughout a large proportion of the column are fastest executed with GENTRANS.
Oxidative Degradation of Polybenzimidazole Membranes as Electrolytes for High Temperature Proton Exchange Membrane Fuel Cells
Authors: Liao J. H. , Li Q. F. , Rudbeck H. C. , Jensen J. O. , Chromik A. , Bjerrum N. J. , Kerres J. , Xing W.
Published: February 2011

Polybenzimidazole membranes imbibed with acid are emerging as a suitable electrolyte material for high‐temperature polymer electrolyte fuel cells. The oxidative stability of polybenzimidazole has been identified as an important issue for the long‐term durability of such cells. In this paper the oxidative degradation of the polymer membrane was studied under the Fenton test conditions by the weight loss, intrinsic viscosity, size exclusion chromatography, scanning electron microscopy and Fourier transform infrared spectroscopy. During the Fenton test, significant weight losses depending on the initial molecular weight of the polymer were observed. At the same time, viscosity and SEC measurements revealed a steady decrease in molecular weight. The degradation of acid doped PBI membranes under Fenton test conditions is proposed to start by the attack of hydroxyl radicals at the carbon atom linking imidazole ring and benzenoid ring, which may eventually lead to the imidazole ring opening and formation of small molecules and terminal groups for further oxidation by an endpoint oxidation.
Depression subtypes and 5‐years risk of mortality in aged 70 years: a population‐based cohort study
Authors: Vilalta‐Franch Joan , Planas‐Pujol Xènia , López‐Pousa Secundino , Llinàs‐Reglà Jordi , Merino‐Aguado Javier , Garre‐Olmo Josep
Published: February 2011

Aims

To estimate the mortality risk related to different mood disorders in a geriatric sample of subjects aged 70 years and over without dementia.

Method

All non‐demented subjects at baseline who participate on a second phase of a population‐based cohort study were included. Adjusted Cox proportional hazards models were used to determine the association between depression and 5‐year survival of 451 elderly people without dementia originally recruited for a representative community dementia cohort study. Baseline evaluation included the Cambridge Mental Disorders of the Elderly Examination Schedule. Depressive disorders (major and minor episode) were assessed according DSM‐IV criteria and classified according the age of onset (late vs. early). The late‐onset depression was classified according to the presence or absence of depression‐executive dysfunction syndrome (DEDS).

Results

The initial cohort size was 451 subjects, among which 10.9% (n = 49) suffered a major depressive episode and 10.4% (n = 47) a minor depressive disorder. Among the total affective disorders, 77.9% (n = 74) were late‐onset depressions and 29.5% (n = 28) had executive dysfunction. After 5 years, the vital status of 94% (n = 424) of the participants was known and the mortality was 18.9% (n = 80). Late‐onset major depressive episode with executive dysfunction was related to mortality after adjustment by age, gender, marital status, level of education, comorbidity (or health global status) and cognitive impairment (HR = 3.70; 95% CI = 1.55–8.83). The executive dysfunction was found to be an independent mortality risk factor (HR = 2.05; 95% CI = 1.15–3.64).

Conclusions

There is a statistically significant association between mortality and late‐onset major depression with executive dysfunction. Copyright © 2011 John Wiley & Sons, Ltd.
Antiproliferative mechanism of a cannabinoid agonist by cell cycle arrest in human gastric cancer cells
Authors: Park Jae Myung , Xian Xiang‐Shu , Choi Myung‐Gyu , Park Hyeyeon , Cho Yu Kyung , Lee In Seok , Kim Sang Woo , Chung In‐Sik
Published: February 2011

For gastric cancers, the antineoplastic activity of cannabinoids has been investigated in only a few reports and knowledge regarding the mechanisms involved is limited. We have reported previously that treatment of gastric cancer cells with a cannabinoid agonist significantly decreased cell proliferation and induced apoptosis. Here, we evaluated the effects of cannabinoids on various cellular mediators involved in cell cycle arrest in gastric cancer cells. AGS and MKN‐1 cell lines were used as human gastric cancer cells and WIN 55,212‐2 as a cannabinoid agonist. Cell cycles were analyzed by flow cytometry and western blotting. Treatment with WIN 55,212‐2 arrested the cell cycle in the G0/G1 phase. WIN 55,212‐2 also upregulated phospho‐ERK1/2, induced Kip1/p27 and Cip1/WAF1/p21 expression, decreased cyclin D1 and cyclin E expression, decreased Cdk 2, Cdk 4, and Cdk 6 expression levels, and decreased phospho‐Rb and E2F‐1 expression. ERK inhibitor decreased the proportion of G0/G1 phase which was induced by WIN 55,212‐2. Inhibition of pAKT led to cell cycle arrest in gastric cancer cells. Cell cycle arrest preceded apoptotic response. Thus, this cannabinoid agonist can reduce gastric cancer cell proliferation via G1 phase cell cycle arrest, which is mediated via activation of the MAPK pathway and inhibition of pAKT. J. Cell. Biochem. 112: 1192–1205, 2011. © 2011 Wiley‐Liss, Inc.
Isolation and characterization of mesenchymal stem cells from human umbilical cord blood: Reevaluation of critical factors for successful isolation and high ability to proliferate and differentiate to chondrocytes as compared to mesenchymal stem cells from bone marrow and adipose tissue
Authors: Zhang Xiaohong , Hirai Masako , Cantero Susana , Ciubotariu Rodica , Dobrila Ludy , Hirsh Allen , Igura Koichi , Satoh Hitoshi , Yokomi Izuru , Nishimura Toshihide , Yamaguchi Satoru , Yoshimura Kotaro , Rubinstein Pablo , Takahashi Tsuneo A.
Published: February 2011

Human umbilical cord blood (CB) is a potential source for mesenchymal stem cells (MSC) capable of forming specific tissues, for example, bone, cartilage, or muscle. However, difficulty isolating MSC from CB (CB‐MSC) has impeded their clinical application. Using more than 450 CB units donated to two public CB banks, we found that successful cell recovery fits a hyper‐exponential function of time since birth with very high fidelity. Additionally, significant improvement in the isolation of CB‐MSC was achieved by selecting cord blood units having a volume ≥90 ml and time ≤2 h after donor's birth. This resulted in 90% success in isolation of CB‐MSC by density gradient purification and without a requirement for immunoaffinity methods as previously reported. Using MSC isolated from bone marrow (BM‐MSC) and adipose tissue (AT‐MSC) as reference controls, we observed that CB‐MSC exhibited a higher proliferation rate and expanded to the order of the 1 × 109 cells required for cell therapies. CB‐MSC showed karyotype stability after prolonged expansion. Functionally, CB‐MSC could be more readily induced to differentiate into chondrocytes than could BM‐MSC and AT‐MSC. CB‐MSC showed immunosuppressive activity equal to that of BM‐MSC and AT‐MSC. Collectively, our data indicate that viable CB‐MSC could be obtained consistently and that CB should be reconsidered as a practical source of MSC for cell therapy and regenerative medicine using the well established CB banking system. J. Cell. Biochem. 112: 1206–1218, 2011. © 2011 Wiley‐Liss, Inc.