bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiwalled carbon nantoubes‐reinforced poly(hydroxyaminoether) prepared by one pot graft‐from method
Authors: Tang Tian , Shi Zixing
Published: December 2010

Multiwalled carbon nanotubes (MWNTs)‐reinforced poly(hydroxyaminoether) (PHAE) was fabricated via one pot graft‐from method. The modification of MWNTs and in situ polymerization of PHAE were combined in one reaction pot without interruption for the purification of modified carbon nanotubes. Fourier transform infrared, scanning electron microscopy, transmission electron microscopy, and Raman spectra clearly indicated that PHAE was successfully attached to the surface of MWNTs via esterification reaction between epoxy and carboxylic acid from MWNTs. Tensile tests showed that the tensile strength and modulus of PHAE/MWNTs composites were improved compared with that of pristine PHAE. Moreover, the reinforcing effect of one pot graft‐from method was found to be better than that of graft‐to method. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis and antimicrobial activity of some cross‐linked copolymers with alkyl chains of various lengths
Authors: Zhang Yuhong , Li Xiaohong , Dong Qinzheng , He Peixin
Published: December 2010

Amphoteric polymer hydrogels were prepared by the copolymerization of three kinds of N,N′‐dimethyl‐N‐alkylmethacryloxylethyl ammoniumbromide (DMAEA) with different lengths of alkyl chains (DMAEA‐RB) (R‐ehtyl/hexyl/dodecyl), acrylic acid (AA), and acrylamide (AM). The water content of the AA‐AM‐(DMAEA‐RB) terpolymers decreased with the increasing length of alkyl chains in quaternary ammonium group in the terpolymers and increased with the increasing molar ratio of DMAEA‐RB to 2 mol % and then decreased. Their antibacterial activities against Escherichia coli and Staphylococcus hyicus were investigated by a colony count method. It was found that the copolymer exhibited higher antibacterial activity with increasing chain length of alkyl groups in ammonium groups. For P[AA‐AM‐(DMAEA‐DB)], the DMAEA‐DB content is higher and contact time is longer, its antibacterial activity is better. However, when the contact time and quaternary ammonium content were above 30 min and 2%, respectively, the amount of live cells N(t) in a cell suspension increased in the presence of P[AA‐AM‐(DMAEA‐EB)] or P[AA‐AM‐(DMAEA‐HB)]. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis of a new type poly(vinyl alcohol)/peat/bamboo charcoal/KNO3 composite bead used as biofilter material
Authors: Chan Wu‐Chung , Chang Shih‐Cheng
Published: December 2010

A new type poly(vinyl alcohol) (PVA)/peat/bamboo charcoal (BC)/KNO3 composite bead was prepared, which has a diameter of 2.4–6.0 mm and a density of 1.133 g/cm3 and is a porous spherical particle. The biochemical kinetic behaviors of n‐butyl acetate in PVA/peat/BC/KNO3 spherical composite bead biofilter (BC biofilter) and PVA/peat/granular activated carbon (GAC)/KNO3 spherical composite bead biofilter (GAC biofilter) were investigated. The values of half‐saturation constant Ks for BC biofilter and GAC biofilter were 27.89 and 27.95 ppm, respectively. The values of maximum reaction rate Vm for BC biofilter and GAC biofilter were 13.49 and 13.65 ppm/s, respectively. Zero‐order kinetic with the diffusion limitation was regarded as the most adequate biochemical reaction model for the two biofilters. The microbial growth rate and biochemical reaction rate for two biofilters were inhibited at higher inlet concentration, and the degree of inhibitive effect was more pronounced in the inlet concentration range of 100–800 ppm. The biochemical kinetic behaviors of the two biofilters were similar. The maximum elimination capacity of BC biofilter and GAC biofilter were 111.65 and 122.67 g C/h m3 bed volume, respectively. The PVA/peat/BC/KNO3 composite bead was suitable as a biofilter material. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
The influence of cross‐linking reaction on the mechanical and thermal properties of polyarylene ether nitrile
Authors: Meng Fanbin , Zhong Jiachun , Chen Yuanwei , Liu Xiaobo
Published: December 2010

The processing of cross‐linked polyarylene ether nitrile (PEN), which has a triazine rings structure, has been investigated under different reaction times and temperatures. In this study, the PEN films prepared by the tape‐casting formed the thermally stable triazine rings by catalytic cross‐linking reaction gradually, which was characterized by Fourier transform infrared spectroscopy. The chemical cross‐linking reaction occurred as the CN group absorption of PEN at 2221 cm−1 decreased and a new absorption peak, at 1682 cm−1, was observed, and the absorption peak intensity would be progressively larger, with the extension of the processing time. After the formation of cross‐linking networks, the cross‐linking degree and thermal and mechanical properties of the processed films were improved substantially, compared with the untreated films. The film with added ZnCl2 as the catalyst was more rapidly cross‐linked, and its properties were better than that without catalyst at the same treatment conditions. The glass‐transition temperature (Tg) of PEN films processed at 350°C for 4 h (213.65°C) was higher than that of PEN films before the treatment (161°C), and the tensile strength was also improved significantly. The PEN was processed at 350°C for 2 h, whose initial decomposition temperature increases by about 10°C, compared with that of untreated film, at one time. The rheology behavior of the cross‐linked films was processed on dynamic rheometer to monitor and track the process of polymer cross‐linking reaction. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis, physical properties, and characterization of starch‐based blend films by adding nano‐sized TiO2/poly(methyl metacrylate‐co‐acrylamide)
Authors: Yun Yeon‐Hum , Hwang Kyung‐Jun , Wee Young‐Jung , Yoon Soon‐Do
Published: December 2010

The purpose of this study was to improve the physical properties and to expand the application range of starch‐based blend films added nano‐sized TiO2/poly(methyl methacrylate‐co‐acrylamide) (PMMA‐co‐AM). Starch‐based blend films were prepared by using corn starch, polyvinyl alcohol (PVA), nano‐sized PMMA‐co‐AM, nano‐sized TiO2/PMMA‐co‐AM particles, and additives, i.e., glycerol (GL) and citric acid (CA). Nano‐sized PMMA‐co‐AM was synthesized by emulsion polymerization and TiO2 nanoparticles were also prepared by using sol–gel method. Nano‐sized TiO2/PMMA‐co‐AM particles were synthesized by wet milling for 48 h. The morphology and crystallinity of TiO2, nano‐sized PMMA‐co‐AM and TiO2/PMMA‐co‐AM particles were investigated by using the scanning electron microscope (SEM) and X‐ray diffractometer (XRD). In addition, the functional groups of the TiO2/PMMA‐co‐AM particles were characterized by IR spectrophotometry (FTIR). The physical properties such as tensile strength (TS), elongation at break (%E), degree of swelling (DS), and solubility (S) of starch‐based films were evaluated. It was found that the adding of nano‐sized particles can greatly improve the physical properties of the prepared films. The photocatalytic degradability of starch/PVA/nano‐sized TiO2/PMMA‐co‐AM composite films was evaluated using methylene blue (MB) and acetaldehyde (ATA) as photodegradation target under UV and visible light. The degree of decomposition (C/C0) of MB and ATA for the films containing TiO2 and CA was 0.506 and 0.088 under UV light irradiation and 0.586 (MB) and 0.631 (ATA) under visible light irradiation, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Tissue and developmental expression of SRAM, an unconventional Rel‐family protein
Authors: Shiraishi Hirohisa , Tanji Takahiro , Natori Shunji , Ohashi‐Kobayashi Ayako
Published: December 2010

Previously we have reported the purification and cDNA cloning of a novel Rel/Ankyrin‐family protein named SRAM from the flesh fly, Sarcophaga peregrina. Rel proteins generally translocate into the nucleus upon immune stimuli by dissociating from an inhibitory ankyrin domain, while SRAM is unique in terms of its constitutive nuclear localization with its internal ankyrin domain accompanied, at least in a Sarcophaga cell line and fat body cells. Although SRAM had been originally identified as a sole factor that binds to the κB motif of the inducible Sarcophaga lectin gene promoter, its transcriptional activity remained controversial. Moreover, homologues of SRAM have not been found in any other established model organisms including Drosophila. Here we report that the developmental expression of SRAM was up‐regulated at the early stages of embryogenesis and metamorphosis. Furthermore, SRAM expression was prominent in the digestive tracts of the third instar larvae. We argue the hypothesis that SRAM has evolved as a quite unconventional Rel‐family protein in Sarcophaga. © 2010 Wiley Periodicals, Inc.
Phosphine and Thiophene Cyclopalladated Complexes: Hydrolysis Reactions in Strong Acidic Media
Authors: García Begoña , Hoyuelos Francisco J. , Ibeas Saturnino , Muñoz María S. , Navarro Ana M. , Peñacoba Indalecio A. , Leal José M.
Published: December 2010

The mechanisms for the hydrolysis of organopalladium complexes [Pd(CNN)R]BF4 (R=P(OPh)3, PPh3, and SC4H8) were investigated at 25 °C by using UV/Vis absorbance measurements in 10 % v/v ethanol/water mixtures containing different sulphuric acid concentrations in the 1.3–11.7 M range. In all cases, a biphasic behavior was observed with rate constants k1obs, which corresponds to the initial step of the hydrolysis reaction, and k2obs, where k1obs>k2obs. The plots of k1obs and k2obs versus sulfuric acid concentration suggest a change in the reaction mechanism. The change with respect to the k1obs value corresponds to 35 %, 2 %, and 99 % of the protonated complexes for R=PPh3, P(OPh)3, and SC4H8, respectively. Regarding k2obs, the change occurred in all cases at about 6.5 M H2SO4 and matched up with the results reported for the hydrolysis of the 2‐acetylpyridinephenylhydrazone (CNN) ligand. By using the excess acidity method, the mechanisms were elucidated by carefully looking at the variation of ki,obs (i=1,2) versus ${c_{{\rm{H}}^ + } }$. The rate‐determining constants, k0,A‐1, k0,A‐2, and k0,A‐SE2 were evaluated in all cases. The R=P(OPh)3 complex was most reactive due to its π‐acid character, which favors the rupture of the trans nitrogen–palladium bond in the A‐2 mechanism and also that of the pyridine nitrogen–palladium bond in the A‐1 mechanism. The organometallic bond exerts no effect on the relative basicity of the complexes, which are strongly reliant on the substituent.
Stability Phenomena in Chemical Reactors
Authors: Gilles E. D.
Published: December 2010

Some important types of non‐linear phenomena occuring in chemically reacting systems are explained by means of some single examples of chemical reactors. Multiple steady‐states exhibiting a distinct behavior of ignition and extinction are in the category of these phenomena. In addition all dynamic instabilities, of which there are a wide variety must also be included. These instabilities might be of thermal or purely kinetic nature, or they may result from the interaction of chemical reaction and physical transport processes. Generally these instabilities result in increasing oscillations which finally converge in stable limit cycles. The moving reaction zone which can appear in fixed‐bed reactors is described in greater detail in order to demonstrate that such a dissipative structure may be considered a prototype of an active transport process. This kind of active transport process can be observed in many systems, which are not limited just to chemical engineering. Furthermore, it is emphasized that a moving reaction zone is characterized by a certain feature which here is called “form stability”. This property might be used in order to considerably reduce the order of the non‐linear equations, describing the reactor behavior. Model reduction is of great importance with respect to both a detailed analysis of the dynamic behavior of a reactor and to the design of control concepts.
Oscillations in Biochemical Systems
Authors: Hess Benno , Boiteux Arnold
Published: December 2010

The general requirements for the occurence of oscillations in a number of various biochemical systems are reviewed. Experimental demonstration of oscillating states in mitochondria, in intact yeast and slime mould cells are given. To demonstrate the minimum requirements for a biochemical oscillator the mechanism of glycolytic oscillations in yeast cells under homogeneous and nonhomogeneous conditions in space is described together with an example of a model subjected to numerical analysis. The general significance of instable states for the creation of domains in time and space is stressed.
Hysteresis, Oscillations, and Pattern Formation in Immobilized Enzyme Systems
Authors: Hervagault J. F. , Friboulet A. , Kernevez J. P. , Thomas D.
Published: December 2010

The immobilization of enzymes within an artificial membrane, with a homogeneous distribution of the active sites, allows a simple modelling in a well defined context. — The systems are described by non‐linear PDE'S, taking into account enzyme reaction and metabolites diffusion. These equations can exhibit several types of behaviors, qualitatively different from those observed in solution, such as hysteresis, oscillations and pattern formations. — Preliminary experimental results have shown the existence of sustained oscillations and instabilities with immobilized acetylcholinesterase and phosphofructokinase.
Prerequisite for Oscillatory Behaviour in the Malonic Acid, Bromate and Catalyst Reacting Systems
Authors: Burger Maria , Körös Endre
Published: December 2010

The role of bromomalonic acid was investigated in Belousov‐Zhabotinsky systems, in the preoscillatory period. It was established that the crucial bromomalonic acid concentration (at which the transition from non‐oscillatory behaviour to the oscillatory one occurs) depends on the initial reactant concentrations. This relationship is closely connected to the rate equation describing the formation of bromomalonic acid in the preoscillatory period. On the basis of the solution of the rate equation the crucial bromomalonic acid concentration can be calculated. From the temperature dependence of the rate constants, the activation energy of the bromomalonic acid formation during the preoscillatory period was calculated.
Reaction Rate Oscillations during the Oxidation of Hydrogen on Nickel
Authors: Kurtanjek Z. , Sheintuch M. , Luss D.
Published: December 2010

Measurements of contact potential difference (CPD) and effluent oxygen concentration were used to monitor oscillations in the surface state and reaction rate during the oxidation of hydrogen over a nickel plate in a continuous flow reactor. CPD measurements indicate that the system oscillates between an active state in which the reduced surface is covered mainly by chemisorbed oxygen and a less active oxidized state. Heat and mass transfer limitations affect the shape, amplitude and period of the oscillations. However, the oscillations do not disappear when transport limitations become negligible.
A Study of the Potential Oscillations of the Alloys on the Basis of Chromium Alloyed with the Metals of the Platinum Group in Solutions of Sulphuric Acid
Authors: Tomashov N. D. , Ustinsky E. N. , Chernova G. P.
Published: December 2010

The present work is devoted to the study of spontaneous periodic potential oscillations under corrosion of ductile chromium with admixtures of 0.1 to 0.4 wt‐% Ru, Os, Ir, Pt, or Pd in still aerated 40 to 55% solutions of H2SO4 at temperatures between 40 and 120°C. — A mechanism has been suggested to describe the formation of potential oscillations on chromium alloys. It is assumed that oscillations appear, when the alloy is in a passive‐active state, as a result of the change in the value of pH in the near‐electrode layer. — It has been established that cathodic additives (Ru, Os, Ir, Pt, Pd) differ in their effect upon the appearance of oscillations of potential on chromium alloys.
Instability and Self‐Oscillations in the Cell Energy Metabolism
Authors: Sel'kov E. E.
Published: December 2010

The temporal organization of the cell energy metabolism is the only way of maintaining a stable ATP concentration within the cell. This type of organization results directly from allosteric regulations of the key futile cycles of the cell energy metabolism such as substrate inhibition and product activation. These regulations switch the antagonist enzymes of the futile cycles on and off reciprocally to suppress recycling via self‐oscillatory changes in the enzyme activities. The deposition effect (E. E. Sel'kov, in: 8th FEBS Meeting, Vol. 25, pp. 145–161, H. C. Hemker and B. Hess, eds., North‐Holland, Amsterdam 1972) allows the oscillations on a circadian time scale.
Preclinical pharmacokinetics and metabolism of MNP001, a piperidine analog of 3‐carbamyl compounds
Authors: Xia Binfeng , Wang Desuo , Fox Laura M.
Published: December 2010

MNP001 is a newly synthesized 3‐carbamyl‐4‐methylpyrrole analog with dual pharmacophores simultaneously to inhibit phosphodiesterase type 4 (PDE4) and to antagonize L‐type calcium channels. The physicochemical properties of MNP001, including solubility, pKa, Log P, plasma protein binding and plasma/blood partitioning, were determined to support the pharmacokinetic characterization. The preclinical pharmacokinetic parameters were determined in anin vivorat model and the metabolic pathways of MNP001 were characterized by incubating the compoundin vitroin rat or human microsomes/supersomes cocktails. MNP001 was found to have a low solubility in simulated intestinal fluid but a high solubility in simulated gastric fluid. MNP001 is a highly lipophilic compound with a LogPvalue greater than 4. MNP001 was highly bound to the plasma protein and had an uneven partition between red blood cells and plasma. MNP001 exhibited a rapid absorption, broad distribution, slow systemic clearance and a low but pharmacologically relevant oral bioavailability in rats. The low oral bioavailability was possibly caused by the low aqueous solubility of MNP001 in the gastrointestinal tract. However, 8 h after oral dosing, the mean plasma level of MNP001 was able to remain about 2‐fold greater than the minimum effective concentration. The major metabolite of MNP001 was defined as a tetrahydropyridine product (MNP001‐M4) of CYP3A4‐mediated phase I oxidation. The possibility that the major metabolite MNP001‐M4 may have a comparable antihypertensive efficacy to MNP001 needs to be studied. Copyright © 2010 John Wiley & Sons, Ltd.
Smoking, the xenobiotic pathway, and clubfoot
Authors: Sommer Amy , Blanton Susan H. , Weymouth Katelyn , Alvarez Christine , Richards B. Stephen , Barnes Douglas , Hecht Jacqueline T.
Published: December 2010

BACKGROUND

Isolated clubfoot is a common orthopedic birth defect that affects approximately 135,000 newborns worldwide. It is characterized by ankle equinus, hindfoot varus, and forefoot adductus. Although numerous studies suggest a multifactorial etiology, the specific genetic and environmental components have yet to be delineated. Maternal smoking during pregnancy is the only common environmental factor consistently shown to increase the risk for clubfoot. Moreover, a positive family history of clubfoot, in conjunction with maternal smoking, increases the risk 20‐fold. These findings suggest that genetic variation in smoking metabolism (xenobiotic) genes may increase susceptibility to clubfoot. Based on this reasoning, we interrogated eight candidate genes from the xenobiotic metabolism.

METHODS

Twenty‐two single‐nucleotide polymorphisms and two null alleles in these genes (CYP1A1, CYP1A2, CYP1B1, CYP2A6, EPHX1, NAT2, GSTM1, and GSTT1) were genotyped in a dataset composed of non‐Hispanic white and Hispanic multiplex and simplex families.

RESULTS

Only rs1048943/CYP1A1 had significantly altered transmission in the aggregate and multiplex non‐Hispanic white datasets (p = 0.003 and p = 0.009, respectively). Perturbation of CYP1A1 can cause an increase in harmful, adduct‐forming metabolic intermediates. A significant interaction between EPHX1 and NAT2 was also found (p = 0.007). Importantly, for CYP1A2, significant maternal (p = 0.03; relative risk [RR] = 1.24; 95% confidence interval [CI], 1.04–1.44) and fetal (p = 0.01; RR = 1.33; 95% CI, 1.13–1.54) genotypic effects were identified, suggesting that both maternal and fetal genotypes can negatively impact limb development. No association was found between maternal smoking status and variation in xenobiotic metabolism genes.

CONCLUSION

Together, these results suggest that xenobiotic metabolism genes are unlikely to play a major role in clubfoot; however, perturbation of this pathway may still play a contributory role. Birth Defects Research (Part A), 2011. © 2010 Wiley‐Liss, Inc.
NAT1,NOS3, and TYMS genotypes and the risk of conotruncal cardiac defects
Authors: Lupo Philip J. , Mitchell Laura E. , Goldmuntz Elizabeth
Published: December 2010

BACKGROUND

Although congenital heart defects (CHDs) are a common and serious group of birth defects, relatively little is known about the causes of these conditions, and there are no established prevention strategies. There is, however, evidence suggesting that the risk of CHDs in general, and conotruncal and related defects (CTRDs) in particular, may be associated with maternal folate status and genetic variants of folate‐related genes. Although several folate‐related genes have been studied as they relate to CHDs and CTRDs (e.g., MTHFR), others have not been adequately assessed.

METHODS

Case‐parent triads were examined using log‐linear analyses to assess the associations between CTRDs and both the genotype inherited by the case and the maternal genotype for the following variants: NAT1 1095C>A, NOS3 894G>T, and TYMS 1494del6. Subgroup analyses were also conducted among cases with classic conotruncal defects and cases with normally related great arteries.

RESULTS

The results provided little evidence that CTRD risk was associated with the genotype inherited by the case for any of the analyzed variants. However, our results suggest that CTRD risk may be associated with the maternal genotype for NOS3 894G>T (p = 0.024 in the subgroup with normally related great arteries) and TYMS 1494del6 (p = 0.048 in the subgroup with classicconotruncal defects). However, these results were not significant after correcting for multiple comparisons.

CONCLUSION

This study provides further evidence that CTRD risk may be related to variation within folate‐pathway genes and suggests that these associations are, at least in part, mediated through the maternal genotype. Birth Defects Research (Part A), 2011. © 2010 Wiley‐Liss, Inc.
Deprotonation of glutamic acid induced by weak magnetic field: An FTIR‐ATR study
Authors: De Ninno A. , Congiu Castellano A.
Published: December 2010

It has been claimed that weak extremely low frequency electromagnetic fields (ELF‐EMFs) can affect biochemical reactions and a wide‐ranging body of literature is available on this topic. Nevertheless, the physical nature of these effects remains largely unknown. We investigated the influence of ELF‐EMF on glutamic acid solutions using Fourier transform infrared‐attenuated total reflectance (FTIR‐ATR) spectra. Samples were exposed for 10, 20, or 30 min to a weak EMF generated by Helmoltz coils, and then placed in a spectrometer. After exposure, those solutions that had a pH lower than the isoelectric point tended to show a shift toward the deprotonation of the carboxylic group, while solutions having a pH greater than the isoelectric point showed the deprotonation of the residual amine group. Moreover, at low pH values, we also detected a shift of the δantisym band of the amine. The effects lasted a few minutes after exposure before the native configuration was restored. The spectral modifications were observed after each independent exposure to EMFs, and the same effects were seen by varying the frequencies in the range of 0–7 kHz. Therefore, the hypothesis of the existence of a resonant frequency that has been proposed elsewhere cannot be supported by the results of this study. The most surprising characteristic of this effect is the long‐lasting nature of the perturbation, which is hard to be explained in terms of short‐living excitations in biological matter. Bioelectromagnetics 32:218–225, 2011. © 2010 Wiley‐Liss, Inc.
Nachweis von Strukturdefekten in Elementwänden mittels zerstörungsfreier Prüfverfahren
Authors: Mähner Dietmar , Thünemann Stefan , Becker Markus
Published: December 2010

Der Beitrag befasst sich mit der Nachweisbarkeit von Strukturdefekten in Elementwänden mittels zerstörungsfreier Prüfverfahren. Innerhalb einer Versuchsreihe wurden in Elementwänden vordefinierte Fehlstellen eingebaut, die während der Betonage auf der Baustelle auftreten können. Die Messungen wurden durch verschiedene Messteams mit Ultraschall‐Echo‐, Impact‐Echo‐ und Impuls‐Radar‐Verfahren an einem vorgegebenen Messraster ausgeführt. Dabei konnten die Strukturdefekte vielfach zerstörungsfrei nachgewiesen werden. Die wesentlichen Untersuchungsergebnisse werden nachfolgend dargestellt.

Verification of Failure in Prefabricated Walls Using Non‐Destructive Testing Methods

This essay deals with the verification of failure in prefabricated walls using non‐destructive testing methods. Series of tests were carried out considering several imperfections which might occur on site during construction. Three measuring methods were used by different parties to carry out the tests. These methods were the Ultrasonic Echo Method, the Impact‐Echo Method and Impulse Radar Technique, where in many cases failure could have been detected in using these methods. The main research results are presented here.
Korrosionsmonitoring von Stahlbetonbauwerken als Element des Lebensdauermanagements
Authors: Holst Alexander , Budelmann Harald , Wichmann Hans‐Joachim
Published: December 2010

Da korrosionsinduzierte Schäden an Bauwerken im Laufe der Zeit zu immensen Kosten führen, sind die sichere Beurteilung des Korrosionsrisikos und eine frühzeitige Erkennung und zuverlässige Vorhersage der Bewehrungskorrosion Schlüsselaufgaben des Bauwerksmanagements korrodierender Spann‐ und Stahlbetonbauwerke. Eine Bewertung des Korrosionszustands wird durch die Bauwerksüberwachung (Monitoring) objektiv möglich.

Im vorliegenden Beitrag werden nach einer kurzen Einführung zum monitoringbasierten Lebensdauermanagement die Entwicklung, Erprobung und Optimierung neuartiger kalibrierungsfreier Miniatursensoren zur Erfassung der Bewehrungskorrosion in Betonbauteilen vorgestellt. Mit diesen vielseitig einsetzbaren Korrosionsstellvertretersensoren, die aus mehreren im Bereich der Betonüberdeckung angeordneten, 0,065 mm bis ca. 0,5 mm dünnen Stahldrähten bestehen, kann das Eindringen der Depassivierungsfront in den Beton einfach, zuverlässig und kostengünstig überwacht werden. Basierend auf umfangreichen Untersuchungen im Labormaßstab und der Anwendungserprobung im Zeitraum von mehr als sechs Jahren werden die Erkenntnisse und Weiterentwicklungen der Drahtsensorik präsentiert und diskutiert.

Corrosion Monitoring as an Element of Service‐Life‐Management

Application of innovative filament sensors for rebar corrosion survey Since corrosion induced damages at civil structures result in enormous costs over lifetime, the assured assessment of the corrosion risk and an early identification and reliable prognosis of rebar corrosion are key tasks of the building management of corroding prestressed and steel reinforced concrete structures. Here an evaluation of the corrosion state is objectively possible by means of Structural Health Monitoring (SHM).

In this contribution after a brief introduction of monitoring based service‐life‐management, the development, testing and optimization of novel calibration‐free miniature sensors for the detection of rebar corrosion in concrete members are introduced. By means of these versatile corrosion dummy sensors, made from several 0,065 mm up to 0,5 mm thin steel filaments and mounted within the concrete cover, the penetration of the depassivation front into concrete can be observed easily, reliably and cost effectively. Based upon various investigations in the lab scale and application testing during the time period of six years, the findings and further developments of the filament sensor will be presented and discussed.
Korrosionsbeständigkeit eines nichtrostenden Chromstahls in karbonatisiertem Normal‐, Leicht‐ und Recyclingbeton
Authors: Hunkeler Fritz , Bäurle Lukas
Published: December 2010

Um der Forderung nach Nachhaltigkeit nachzukommen, wird in den nächsten Jahren der Einsatz von Betonen mit rezyklierten Gesteinskörnungen (Beton‐ und Mischabbruch) zunehmen. Wegen den wärmedämmenden Eigenschaften wird auch der Bedarf an Betonen mit Leichtzuschlägen (z. B. Blähglas) steigen. Als wesentliches Element dieser Entwicklung werden für die Zementund Betonproduktion zunehmend Zemente mit reduziertem Portlandzementklinkergehalt sowie Zusatzstoffe wie Flugasche und Hüttensand verwendet. Damit nimmt der Karbonatisierungswiderstand der Betone tendenziell ab und das Risiko für Korrosionsschäden zu. Die nachfolgend vorgestellten Untersuchungen hatten zum Ziel, die Korrosionsbeständigkeit eines nichtrostenden Chromstahls (Top12, Zusammensetzung entspricht ungefähr dem Stahl mit der Werkstoffnummer 1.4003) in karbonatisiertem Beton mit unterschiedlicher Zusammensetzung zu evaluieren, mit normalem Betonstahl zu vergleichen und zu beurteilen. Die Ergebnisse lassen den Schluss zu, dass der Top12, im Gegensatz zum normalen Betonstahl, in allen untersuchten Betonen und damit auch in stark karbonatisierten Recyclingbetonen beständig ist.

Corrosion Resistance of a Stainless Chromium‐Steel in Carbonated Ordinary, Light‐Weight and Recycling Concrete

In order to achieve the goals for a sustainable development, concrete with recycled aggregates (concrete and mixtures from concrete and masonry, e.g. clay bricks and calcium silicate blocks etc.) is going to be used more and more in the future. Due to its thermal insulating properties, the demand for concrete with light‐weight aggregates (e.g. foam glass) will also increase. As an essential element of this development, an increasing amount of cements with a reduced clinker factor as well as of mineral additions such as fly ash and ground granulated blast furnace slag is used for concrete production. Therefore, as a general tendency, the carbonation resistance of concrete mixes decreases while the risk of corrosion damages increases. The goal of the investigations described in this paper was to evaluate and to assess the corrosion resistance of a stainless rebar (Top12, composition corresponds approx. to steel grade 1.4003) in various carbonated concrete mixes and to compare the results with common rebars. The results lead to the conclusion that, in contrast to common rebars, Top12 is durable in all investigated concrete mixes, including strongly carbonated recycling concretes.
A gaussian model for substrates of entangled cross‐linked poly(ethylene glycol) in biomedical applications
Authors: Eskandari Mahnaz , Brey Eric , Cinar Ali
Published: December 2010

Cells usually spread on a synthetic substrate through bonds between receptors and chemical groups on the substrate (ligands). Therefore, it is valuable to study the effects of the average number density of these chemical groups and the average distance between them to model and predict the cell behavior. Poly(ethylene glycol) [PEG] modified with peptide groups has been used widely in biomedical applications as a substrate material. In this study, a coarse‐grained model is proposed for PEG to predict the average number density of ligands and the average distance between them. Molecular information such as initial molecular weight distribution, average molecular weight between cross‐links, and average molecular weight between entanglements is used as input parameters. Based on simulation results, it is concluded that both entanglement and cross‐link densities are required to create a network structure. The results suggest that an average initial molecular weight 2–3 times the average molecular weight between entanglements and a moderate cross‐link density are sufficient to create a closed network structure with a high ligand density and a small average distance between them. Biotechnol. Bioeng. 2011;108: 435–445. © 2010 Wiley Periodicals, Inc.
Ionic liquid pretreatment of cellulosic biomass: Enzymatic hydrolysis and ionic liquid recycle
Authors: Shill Kierston , Padmanabhan Sasisanker , Xin Qin , Prausnitz John M. , Clark Douglas S. , Blanch Harvey W.
Published: December 2010

Ionic liquids (ILs) are promising solvents for the pretreatment of biomass as certain ILs are able to completely solubilize lignocellulose. The cellulose can readily be precipitated with an anti‐solvent for further hydrolysis to glucose, but the anti‐solvent must be removed for the IL to be recovered and recycled. We describe the use of aqueous kosmotropic salt solutions to form a three‐phase system that precipitates the biomass, forming IL‐rich and salt‐rich phases. The phase behavior of [Emim][Ac] and aqueous phosphate salt systems is presented, together with a process for recycling the [Emim][Ac] and enzymatically hydrolyzing the cellulose. This process reduces the amount of water to be evaporated from recycled IL, permitting efficient recycle of the IL. Material balances on the process, with multiple recycles of the [Emim][Ac], quantify the major components from a Miscanthus feedstock through the pretreatment, separation, and enzymatic hydrolysis steps. A more rapid and higher yielding conversion of cellulose to glucose is obtained by use of the three‐phase system as compared to the cellulose obtained from biomass pretreated with IL and precipitated with water. The addition of a kosmotropic salt during the precipitation results in partial delignification of the biomass, which makes the substrate more accessible, enhancing the enzymatic hydrolysis. Biotechnol. Bioeng. 2011; 108:511–520. © 2010 Wiley Periodicals, Inc.
Microalgae—novel highly efficient starch producers
Authors: Brányiková Irena , Maršálková Barbora , Doucha Jiří , Brányik Tomáš , Bišová Kateřina , Zachleder Vilém , Vítová Milada
Published: December 2010

The freshwater alga Chlorella, a highly productive source of starch, might substitute for starch‐rich terrestrial plants in bioethanol production. The cultivation conditions necessary for maximizing starch content in Chlorella biomass, generated in outdoor scale‐up solar photobioreactors, are described. The most important factor that can affect the rate of starch synthesis, and its accumulation, is mean illumination resulting from a combination of biomass concentration and incident light intensity. While 8.5% DW of starch was attained at a mean light intensity of 215 µmol/(m2 s1), 40% of DW was synthesized at a mean light intensity 330 µmol/(m2 s1). Another important factor is the phase of the cell cycle. The content of starch was highest (45% of DW) prior to cell division, but during the course of division, its cellular level rapidly decreased to about 13% of DW in cells grown in light, or to about 4% in those kept in the dark during the division phase. To produce biomass with high starch content, it is necessary to suppress cell division events, but not to disturb synthesis of starch in the chloroplast. The addition of cycloheximide (1 mg/L), a specific inhibitor of cytoplasmic protein synthesis, and the effect of element limitation (nitrogen, sulfur, phosphorus) were tested. The majority of the experiments were carried out in laboratory‐scale photobioreactors, where culture treatments increased starch content to up to about 60% of DW in the case of cycloheximide inhibition or sulfur limitation. When the cells were limited by phosphorus or nitrogen supply, the cellular starch content increased to 55% or 38% of DW, respectively, however, after about 20 h, growth of the cultures stopped producing starch, and the content of starch again decreased. Sulfur limited and cycloheximide‐treated cells maintained a high content of starch (60% of DW) for up to 2 days. Sulfur limitation, the most appropriate treatment for scaled‐up culture of starch‐enriched biomass, was carried out in an outdoor pilot‐scale experiment. After 120 h of growth in complete mineral medium, during which time the starch content reached around 18% of DW, sulfur limitation increased the starch content to 50% of DW. Biotechnol. Bioeng. 2011; 108:766–776. © 2010 Wiley Periodicals, Inc.
Developing the TriLab, a triple access mode (hands‐on, virtual, remote) laboratory, of a process control rig using LabVIEW and Joomla
Authors: Abdulwahed Mahmoud , Nagy Zoltan K.
Published: December 2010

Laboratory education is a core part of engineering curricula; engineering students generally prefer to work on something real. The classical mode and the oldest form of laboratory education is the hands‐on mode. Advances in information and communication technologies have contributed to the laboratory education by creating two new modes, the simulated (virtual) mode and the online controlled mode (remote). Recently, developments or utilizations of hybrid structures of two types (e.g., virtual and hands‐on, or remote and hands‐on) have been reported in the literature; however, until now there are no reports of hybrid structures of the three types together. This paper describes the technical development of a novel laboratory model that combines the three modes in one unifying software package, namely the TriLab, by using Laboratory Virtual Instrument Engineering Workbench (LabVIEW). It is shown that LabVIEW provides a single programming environment for developing all components of the TriLab. Furthermore, it is shown that the Joomla web content management system can be used as a solution for efficient deployment of a remote lab online portal on the top of the LabVIEW core software. The development of the TriLab using LabVIEW and Joomla for an Instrumentation and Control Engineering Laboratory rig is shown. The analysis of student survey is presented which has shown positive impact of the pedagogical utilization of the TriLab. This is the first paper which aims to provide engineering academics a generic architecture and software solutions to rapidly develop their own TriLab. © 2010 Wiley Periodicals, Inc. Comput Appl Eng Educ 21: 614–626, 2013
Ultra‐small gadolinium oxide nanoparticles to image brain cancer cells in vivo with MRI
Authors: Faucher Luc , Guay‐Bégin Andrée‐Anne , Lagueux Jean , Côté Marie‐France , Petitclerc Éric , Fortin Marc‐André
Published: December 2010

The majority of contrast agents used in magnetic resonance imaging (MRI) is based on the rare‐earth element gadolinium. Gadolinium‐based nanoparticles could find promising applications in pre‐clinical diagnostic procedures of certain types of cancer, such as glioblastoma multiforme. This is one of the most malignant, lethal and poorly accessible forms of cancer. Recent advances in colloidal nanocrystal synthesis have led to the development of ultra‐small crystals of gadolinium oxide (US‐Gd2O3, 2–3 nm diameter). As of today, this is the smallest and the densest of all Gd‐containing nanoparticles. Cancer cells labeled with a sufficient quantity of this compound appear bright in T1‐weighted MRI images. Here we demonstrate that US‐Gd2O3 can be used to label GL‐261 glioblastoma multiforme cells, followed by localization and visualization in vivo using MRI. Very high amounts of Gd are efficiently internalized and retained in cells, as confirmed with TEM and ICP‐MS. Labeled cells were visualized in vivo at 1.5 T using the chicken embryo model. This is one more step toward the development of “positively contrasted” cell tracking procedures with MRI. Copyright © 2010 John Wiley & Sons, Ltd.
Nitric oxidergic cells related to ejaculation in gerbil forebrain contain androgen receptor and respond to testosterone
Authors: Simmons Danielle A. , Yahr Pauline
Published: December 2010

Two clusters of forebrain neurons—one in the posterodorsal preoptic nucleus (PdPN) and one in the lateral part of the posterodorsal medial amygdala (MeApd)—are activated at ejaculation in male rats and gerbils as seen with Fos immunocytochemistry. To understand the functions of these cells and how they respond synchronously, it may be useful to identify their neurotransmitters. Nitric oxide (NO) was of interest because its levels in the preoptic area affect ejaculation, and it could synchronize clustered neurons through paracrine/volume transmission. Thus, we determined whether the ejaculation‐related cells produce NO by assessing Fos co‐localization with NO synthase (NOS) in recently mated male gerbils. We also studied NOS‐Fos co‐localization in the medial part of the medial preoptic nucleus (MPNm), where half of the neurons that express Fos after mating reflect ejaculation. We also quantified NOS co‐localization with androgen receptor (AR) and NOS sensitivity to androgens at these sites. Without quantification, we extended these analyses throughout the hypothalamus and amygdala. Many mating‐activated PdPN, lateral MeApd, and MPNm cells contained NOS (32–54%), and many NOS neurons at these sites expressed Fos (34–51%) or AR (25–69%). PdPN and MPNm NOS cells were sensitive to testosterone but not its androgenic metabolite dihydrotestosterone. The overall distribution of NOS and NOS‐AR cells was similar to that in rats. These data suggest that NO may help to synchronize the activation of PdPN and lateral MeApd neurons at ejaculation and that NOS in PdPN and MPNm cells is regulated by testosterone acting via estradiol or without undergoing metabolism. J. Comp. Neurol. 519:900–915, 2011. © 2010 Wiley‐Liss, Inc.
Reassessment of the structural basis of the ascending arousal system
Authors: Fuller Patrick , Sherman David , Pedersen Nigel P. , Saper Clifford B. , Lu Jun
Published: December 2010

The “ascending reticular activating system” theory proposed that neurons in the upper brainstem reticular formation projected to forebrain targets that promoted wakefulness. More recent formulations have emphasized that most neurons at the pontomesencephalic junction that participate in these pathways are actually in monoaminergic and cholinergic cell groups. However, cell‐specific lesions of these cell groups have never been able to reproduce the deep coma seen after acute paramedian midbrain lesions that transect ascending axons at the caudal midbrain level. To determine whether the cortical afferents from the thalamus or the basal forebrain were more important in maintaining arousal, we first placed large cell‐body‐specific lesions in these targets. Surprisingly, extensive thalamic lesions had little effect on electroencephalographic (EEG) or behavioral measures of wakefulness or on c‐Fos expression by cortical neurons during wakefulness. In contrast, animals with large basal forebrain lesions were behaviorally unresponsive and had a monotonous sub‐1‐Hz EEG, and little cortical c‐Fos expression during continuous gentle handling. We then retrogradely labeled inputs to the basal forebrain from the upper brainstem, and found a substantial input from glutamatergic neurons in the parabrachial nucleus and adjacent precoeruleus area. Cell‐specific lesions of the parabrachial‐precoeruleus complex produced behavioral unresponsiveness, a monotonous sub‐1‐Hz cortical EEG, and loss of cortical c‐Fos expression during gentle handling. These experiments indicate that in rats the reticulo‐thalamo‐cortical pathway may play a very limited role in behavioral or electrocortical arousal, whereas the projection from the parabrachial nucleus and precoeruleus region, relayed by the basal forebrain to the cerebral cortex, may be critical for this process. J. Comp. Neurol. 519:933–956, 2011. © 2010 Wiley‐Liss, Inc.
SNAP25 expression in mammalian retinal horizontal cells
Authors: Hirano Arlene A. , Brandstätter Johann Helmut , Morgans Catherine W. , Brecha Nicholas C.
Published: December 2010

Horizontal cells mediate inhibitory feedforward and feedback lateral interactions in the outer retina at photoreceptor terminals and bipolar cell dendrites; however, the mechanisms that underlie synaptic transmission from mammalian horizontal cells are poorly understood. The localization of a vesicular γ‐aminobutyric acid (GABA) transporter (VGAT) to horizontal cell processes in primate and rodent retinae suggested that mammalian horizontal cells release transmitter in a vesicular manner. Toward determining whether the molecular machinery for vesicular transmitter release is present in horizontal cells, we investigated the expression of SNAP25 (synaptosomal‐associated protein of 25 kDa), a key SNARE protein, by immunocytochemistry with cell type‐specific markers in the retinae of mouse, rat, rabbit, and monkey. Different commercial antibodies to SNAP25 were tested on vertical sections of retina. We report the robust expression of SNAP25 in both plexiform layers. Double labeling with SNAP25 and calbindin antibodies demonstrated that horizontal cell processes and their endings in photoreceptor triad synapses were strongly labeled for both proteins in mouse, rat, rabbit, and monkey retinae. Double labeling with parvalbumin antibodies in monkey retina verified SNAP25 immunoreactivity in all horizontal cells. Pre‐embedding immunoelectron microscopy in rabbit retina confirmed expression of SNAP25 in lateral elements within photoreceptor triad synapses. The SNAP25 immunoreactivity in the plexiform layers and outer nuclear layer fell into at least three patterns depending on the antibody, suggesting a differential distribution of SNAP25 isoforms. The presence of SNAP25a and SNAP25b isoforms in mouse retina was established by reverse transcriptase‐polymerase chain reaction. SNAP25 expression in mammalian horizontal cells along with other SNARE proteins is consistent with vesicular exocytosis. J. Comp. Neurol. 519:972–988, 2011. © 2010 Wiley‐Liss, Inc.
Adsorption of Hydroxyacetone on Pure Ice Surfaces
Authors: Petitjean Mélanie , Darvas Maria , Picaud Sylvain , Jedlovszky Pál , Le Calvé Stéphane
Published: December 2010

The adsorption of hydroxyacetone molecules at the surface of ice is investigated by means of flow‐tube reactor measurements in the temperature range: 213–253 K. The number of molecules adsorbed per surface unit is conventionally plotted as a function of the absolute gas concentration of hydroxyacetone and is compared to that previously obtained for acetone and ethanol. The enthalpy of adsorption and the monolayer capacity at the ice surface are determined. In addition, molecular dynamics simulations are performed to support the experimental results. However, it is shown that the available interaction potential between hydroxyacetone and ice is not accurate enough to allow a robust detailed analysis of the adsorption process. Finally, a rapid estimation of the hydroxyacetone partitioning between the gas phase and ice shows that in the densest ice clouds, up to 29 % of hydroxyacetone could be adsorbed on pure ice surfaces at 203 K.
Angiotensins
Authors: Ballermann Barbara J. , Onuigbo Macaulay A. C.
Published: December 2010

The sections in this article are:

Angiotensin Generation and Metabolism

Classic Pathway of Angiotensin II Generation

Alternative Pathways Generating Angiotensin Peptides

Angiotensin Actions in the Kidney

Regulation of Intrarenal Hemodynamics

Angiotensin II Actions on Renal Tubule Epithelial Transport

Coordination of Renal Vascular and Epithelial Angiotensin II Actions

Cardiovascular Actions of Angiotensin II

Effects on Blood Vessels

Cardiac Actions

Adrenal Actions of Angiotensin

Adrenal Angiotensin II Receptors

Mechanisms of Angiotensin II‐Stimulated Aldosterone Synthesis

Mechanisms of Adrenal Glomerulosa Cell Activation

Trophic Effects on the Adrenal Gland

Central Nervous System Actions of Angiotensin II

Expression of Renin‐Angiotensin System Components

Angiotensin II‐Mediated Drinking, Vasopressin Release, and Salt Intake

Centrally Mediated Effects on Blood Pressure

Cellular Mechanisms

Angiotensin II Receptors

Angiotensin II Receptor Subtypes

Regulation of Receptor Expression

Receptor Structure‐Function Relationships

Receptor Signaling Mechanisms

Conclusions