bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kathodischer Korrosionsschutz an Bauwerksfugen
Authors: Sodeikat Christian , Mayer Till Felix , Schöning Markus 
Published: May 2011

AbstractDer kathodische Korrosionsschutz (KKS) hat sich als wirtschaftlich und technisch sinnvolle Alternative zur herkömmlichen Betoninstandsetzung chloridbeaufschlagter Stahlbetonbauwerke zunehmend etabliert, da im Gegensatz zu dieser auf aufwändige Eingriffe in die bestehende Bausubstanz in der Regel verzichtet werden kann. In einigen Fällen ist der kathodische Korrosionsschutz sogar die einzig mögliche Instandsetzungsvariante, da ein Betonabtrag nicht oder nur mit einem unverhältnismäßig hohen Aufwand z. B. für Abstützmaßnahmen oder Verkehrssperrungen durchgeführt werden kann. Eine derartige Anwendung wird in dem folgenden Beispiel beschrieben. Dabei handelt es sich um die Instandsetzung des Stachusbauwerks in München, bei dem die hoch chloridbelasteten und vorgespannten Bauwerksfugen der Bayer‐ und Sonnenstraße mit aufbetonierten Bandanoden geschützt wurden. Die Planung und Installation des KKS‐Systems aus Sicht des Bauherrn und des planenden Ingenieurbüros sowie die Ergebnisse der Depolarisationsmessungen rd. ein Jahr nach Inbetriebnahme der Anlage werden in diesem Beitrag erläutert.
Zum Ansatz eines kritischen Chloridgehaltes bei Stahlbetonbauwerken
Authors: Breit Wolfgang , Dauberschmidt Christoph , Gehlen Christoph , Sodeikat Christian , Taffe Alexander , Wiens Udo 
Published: May 2011

AbstractDer Chloridgehalt, ab dem bei der Bewehrung im Beton mit Korrosion gerechnet werden muss, wird als kritischer Chloridgehalt bezeichnet. Die Höhe dieses kritischen Chloridgehaltes bestimmt in hohem Maße den Instandsetzungsumfang und damit die Instandsetzungskosten. Zahlreiche Labor‐ und Bauwerksuntersuchungen belegen, dass dieser kritische Chloridgehalt von einer Vielzahl von Parametern abhängt und deswegen kein fester Wert sein kann. Aus diesem Grund ist es sinnvoll, über Betrachtung von Korrosions‐ bzw. Depassivierungswahrscheinlichkeiten einen unteren kritischen Chloridgehalt zu bestimmen, bei dem bei gegebenen Randbedingungen nur mit einer geringen Wahrscheinlichkeit (z. B. 5%‐Fraktilwert) Korrosion von Stahl in Beton zu erwarten ist. Die Auswertung von zahlreichen Untersuchungen zeigt, dass der Ansatz eines kritischen Chloridgehaltes von 0, 5 M.‐% bezogen auf den Zementgehalt bei Einhaltung bestimmter Randbedingungen mit einer hinreichend geringen Korrosionswahrscheinlichkeit korreliert und somit auch in Übereinstimmung mit der Richtlinie “Schutz und Instandsetzung von Betonbauteilen” des DAfStb als unterer kritischer Chloridgehalt unter Praxisbedingungen anzusetzen ist.Approach for the Critical Chloride Content of RC structuresThe chloride content, which can lead to corrosion of the reinforcement in concrete, is defined as the critical chloride content. This critical chloride content determines the extent of repair measures and thus the costs significantly. Numerous laboratory and structure investigations show, that the critical chloride content depends on many parameter and thus can not be a fixed values. Hence it is reasonable to determine a lower value of the critical chloride content by evaluating the depassivation probability linked with a low probability (e.g. 5% fractile value) of corrosion under given circumstances. The evaluation of numerous investigations shows that the approach of 0.5 mass % relative to cement content corresponds with an acceptably low probability of corrosion considering given circumstances. This is in accordance with the German Guideline for Protection and Repair Measures for RC‐structures under practical conditions.
Untersuchungen zum kritischen korrosionsauslösenden Chloridgehalt unter Berücksichtigung der Kontaktzone zwischen Stahl und Beton
Authors: Harnisch Jörg , Raupach Michael 
Published: May 2011

AbstractIm folgenden Beitrag werden die Ergebnisse eines Gemeinschaftsprojektes zwischen dem Techion in Haifa, Israel und dem Institut für Bauforschung der RWTH Aachen (ibac) vorgestellt. Ziel des Projektes war es, den Einfluss der Kontaktzone auf den kritischen korrosionsauslösenden Chloridgehalt für unlegierten Stahl in Beton besser zu verstehen. Zu diesem Zweck wurden am ibac an insgesamt 15 Betonvariationen elektrochemische Untersuchungen zur Ermittlung des Depassivierungszeitpunktes sowie nasschemische Analysen zur Bestimmung des vorliegenden Gesamtchloridgehaltes auf Höhe der Bewehrung durchgeführt. Jede Betonvariation wurde mit “stehender” (parallel zur Betonierrichtung) sowie “liegender” (orthogonal zur Betonierrichtung) Bewehrungsführung hergestellt, um neben den betontechnologischen Aspekten auch baupraktisch relevante Einflüsse auf die Kontaktzone zu erfassen. Die Ergebnisse zeigen, dass betontechnologische Variationen einen starken Einfluss auf die Initiierungszeit ausüben. Hinsichtlich des festgestellten korrosionsauslösenden Chloridgehaltes dominiert jedoch der Einfluss der Bewehrungslage. Diesem Aspekt sollte daher bei der Entwicklung von Prüfverfahren unbedingt Rechnung getragen werden.Investigations Into the Time to Corrosion and Corrosion Initiating Chloride Contents for Steel in ConcreteThe present paper highlights the results of a German‐Israeli research project. The research work was conducted in order to improve the understanding for the influence of the interfacial transition zone (ITZ) between steel and concrete on the critical (corrosion inducing) chloride content for black steel in concrete. In order to reach that goal an extensive electrochemical test series covering 15 different concrete mixes was established aiming at initiation times and critical chloride contents. For each concrete mix a pair of test specimens with a vertical and a horizontal rebar arrangement with regard to the cast direction was investigated. In this way it was possible to consider not only the influence of mix variations but also of craftsmanship on the ITZ. The results show that mix variations have a measurable impact on the initiation time while the formation of the critical chloride content seems to be dominated by the rebar arrangement. It is emphasized that these aspects should be considered in any test procedure regarding the critical chloride content of black steel in concrete.
Characterization of stem cells and cancer cells on the basis of gene expression profile stability, plasticity, and robustness
Authors: Kaneko Kunihiko 
Published: May 2011

AbstractHere I present and discuss a model that, among other things, appears able to describe the dynamics of cancer cell origin from the perspective of stable and unstable gene expression profiles. In identifying suchaberrantgene expression profiles as lying outside the normal stable states attracted through development and normal cell differentiation, the hypothesis explains why cancer cells accumulate mutations, to which they are not robust, and why these mutations create a new stable state far from the normal gene expression profile space. Such cells are in strong contrast with normal cell types that appeared as an attractor state in the gene expression dynamical system under cell‐cell interaction and achieved robustness to noise through evolution, which in turn also conferred robustness to mutation. In complex gene regulation networks, otheraberrantcellular states lacking such high robustness are expected to remain, which would correspond to cancer cells.
Nrf2‐mediated induction of phase 2 detoxifying enzymes by glyceollins derived from soybean exposed to Aspergillus sojae
Authors: Kim Hyo Jung , di Luccio Eric , Kong Ah‐Ng Tony , Kim Jong‐Sang 
Published: May 2011

AbstractNumerous antioxidants have been reported to cause transcriptional activation of several antioxidant enzymes through binding antioxidant‐response element on their promoter region. We, therefore, attempted to examine whether glyceollins, which share common structural features with many phase 2 enzyme inducers and antioxidant activity, could induce detoxifying/antioxidant enzymes. Glyceollins induced NAD(P)H:quinone oxidoreductase activity in a dose‐dependent manner in both mouse hepatoma Hepa1c1c7 and its mutant BPRc1 cells. The compounds also increased the expression of some representative antioxidant enzymes, such as heme oxygenase 1,gamma‐glutamylcysteine synthase, and glutathione reductase, by promoting nuclear translocation of the NF‐E2‐related factor‐2 (Nrf2). Furthermore, phosphorylation of Akt and antioxidant response element‐mediated reporter gene expression were enhanced by glyceollins but suppressed by LY294002, an inhibitor of phosphoinositide 3‐kinases (PI3K). This suggests that glyceollins may cause Nrf2‐mediated phase 2 enzyme induction through activation of the PI3K signaling pathway as well as interaction with Keap1. Our molecular docking simulations also suggest that the glyceollin isomers tightly bind into the binding pocket around Cys151, preventing Nrf2 from docking to Keap1. In conclusion, the current data suggest that glyceollins induced phase 2 detoxifying enzymes likely through promoting nuclear translocation of Nrf2, which is known to be regulated by phosphorylation of Nrf2 and/or disrupting Keap1‐Nrf2 complex formation.
Peptide–glycosaminoglycan cluster formation involving cell penetrating peptides
Authors: Rullo Anthony , Qian Jieshu , Nitz Mark 
Published: May 2011

AbstractGlycosaminoglycans (GAGs) affect the efficiency of cellular uptake of a wide range of cell penetrating peptides (CPPs). GAGs have been proposed to cluster with CPPs at the cell surface before uptake but little is known about the formation or stability of CPP–GAG clusters. Here we apply a combination of heparin affinity chromatography, dynamic light scattering, and fluorescence spectroscopy to characterize the formation, stability, and size of the clusters formed between CPPs and heparin. Under conditions similar to those used in cell uptake experiments the CPP, penetratin (Antp), was observed to form significantly more stable clusters with heparin than the CPP TAT, despite TAT showing a comparable affinity for heparin. This difference in cluster stability may explain the origins of the preferred cell uptake pathways followed by Antp and TAT, and may be an important parameter for optimizing the efficiency of designed CPP delivery vectors. © 2011 Wiley Periodicals, Inc. Biopolymers 95: 722–731, 2011.
Aptamer‐based downstream processing of his‐tagged proteins utilizing magnetic beads
Authors: Kökpinar Öznur , Walter Johanna‐Gabriela , Shoham Yuval , Stahl Frank , Scheper Thomas 
Published: May 2011

AbstractAptamers are synthetic nucleic acid‐based high affinity ligands that are able to capture their corresponding target via molecular recognition. Here, aptamer‐based affinity purification for His‐tagged proteins was developed. Two different aptamers directed against the His‐tag were immobilized on magnetic beads covalently. The resulting aptamer‐modified magnetic beads were characterized and successfully applied for purification of different His‐tagged proteins from complex E. coli cell lysates. Purification effects comparable to conventional immobilized metal affinity chromatography were achieved in one single purification step. Moreover, we have investigated the possibility to regenerate and reuse the aptamer‐modified magnetic beads and have shown their long‐term stability over a period of 6 months. Biotechnol. Bioeng. 2011;108: 2371–2379. © 2011 Wiley Periodicals, Inc.
Recombinant human gelatin substitute with photoreactive properties for cell culture and tissue engineering
Authors: Kitajima Takashi , Obuse Sei , Adachi Takahiro , Tomita Masahiro , Ito Yoshihiro 
Published: May 2011

AbstractThe human recombinant collagen I α1 chain monomer (rh‐gelatin) was modified by the incorporation of an azidophenyl group to prepare photoreactive human gelatin (Az‐rh‐gelatin), with approximately 90% of the lysine residues conjugated with azidobenzoic acid. Slight changes in conformation (circular dichroism spectra) and thermal properties (gelation and melting points) were noticed after modification. Ultraviolet (UV) irradiation could immobilize the Az‐rh‐gelatin on polymer surfaces, such as polystyrene and polytetrafluoroethylene. Az‐rh‐gelatin was stably retained on the polymer surfaces, while unmodified gelatin was mostly lost by brief washing. Human mesenchymal cells grew more efficiently on the immobilized surface than on the coated surface. The immobilized Az‐rh‐gelatin on the polymer surfaces was able to capture engineered growth factors with collagen affinity, and the bound growth factors stimulated the growth of cells dose‐dependently. It was also possible to immobilize Az‐rh‐gelatin in micropatterns (stripe, grid, and so on) using photomasks, and the cells grew according to the patterns. These results suggest that the photoreactive human gelatin, in combination with collagen‐binding growth factors, will be clinically useful for surface modification of synthetic materials for cell culture systems and tissue engineering. Biotechnol. Bioeng. 2011;108: 2468–2476. © 2011 Wiley Periodicals, Inc.
Cell‐mediated deposition of porous silica on bacterial biofilms
Authors: Jaroch David , McLamore Eric , Zhang Wen , Shi Jin , Garland Jay , Banks M. Katherine , Porterfield D. Marshall , Rickus Jenna L. 
Published: May 2011

AbstractLiving hybrid materials that respond dynamically to their surrounding environment have important applications in bioreactors. Silica based sol–gels represent appealing matrix materials as they form a mesoporous biocompatible glass lattice that allows for nutrient diffusion while firmly encapsulating living cells. Despite progress in sol–gel cellular encapsulation technologies, current techniques typically form bulk materials and are unable to generate regular silica membranes over complex geometries for large‐scale applications. We have developed a novel biomimetic encapsulation technique whereby endogenous extracellular matrix molecules facilitate formation of a cell surface specific biomineral layer. In this study, monoculture Pseudomonas aeruginosa and Nitrosomonas europaea biofilms are exposed to silica precursors under different acid conditions. Scanning electron microscopy (SEM) imaging and electron dispersive X‐ray (EDX) elemental analysis revealed the presence of a thin silica layer covering the biofilm surface. Cell survival was confirmed 30 min, 30 days, and 90 days after encapsulation using confocal imaging with a membrane integrity assay and physiological flux measurements of oxygen, glucose, and NH. No statistical difference in viability, oxygen flux, or substrate flux was observed after encapsulation in silica glass. Shear induced biofilm detachment was assessed using a particle counter. Encapsulation significantly reduced detachment rate of the biofilms for over 30 days. The results of this study indicate that the thin regular silica membrane permits the diffusion of nutrients and cellular products, supporting continued cellular viability after biomineralization. This technique offers a means of controllably encapsulating biofilms over large surfaces and complex geometries. The generic deposition mechanism employed to form the silica matrix can be translated to a wide range of biological material and represents a platform encapsulation technology. Biotechnol. Bioeng. 2011;108: 2249–2260. © 2011 Wiley Periodicals, Inc.
Synergistic capture of Clostridium botulinum type A neurotoxin by scFv antibodies to novel epitopes
Authors: Gray Sean A. , Barr John R. , Kalb Suzanne R. , Marks James D. , Baird Cheryl L. , Cangelosi Gerard A. , Miller Keith D. , Feldhaus Michael J. 
Published: May 2011

AbstractA non‐immune library of human single chain fragment variable (scFv) antibodies displayed on Saccharomyces cerevisiae was screened for binding to the Clostridium botulinum neurotoxin serotype A binding domain [BoNT/A (Hc)] with the goal of identifying scFv to novel epitopes. To do this, an antibody‐mediated labeling strategy was used in which antigen‐binding yeast clones were selected after labeling with previously characterized monoclonal antibodies (MAbs) specific to the Hc. Twenty unique scFv clones were isolated that bound Hc. Of these, 3 also bound to full‐length BoNT/A toxin complex with affinities ranging from 5 to 48 nM. Epitope binning showed that the three unique clones recognized at least two epitopes distinct from one another as well as from the detection MAbs. After production in E. coli, scFv were coupled to magnetic particles and tested for their ability to capture BoNT/A holotoxin using an Endopep‐MS assay. In this assay, toxin captured by scFv coated magnetic particles was detected by incubation of the complex with a peptide containing a BoNT/A‐specific cleavage sequence. Mass spectrometry was used to detect the ratio of intact peptide to cleavage products as evidence for toxin capture. When tested individually, each of the scFv showed a weak positive Endopep‐MS result. However, when the particles were coated with all three scFv simultaneously, they exhibited significantly higher Endopep‐MS activity, consistent with synergistic binding. These results demonstrate novel approaches toward the isolation and characterization of scFv antibodies specific to unlabeled antigens. They also provide evidence that distinct scFv antibodies can work synergistically to increase the efficiency of antigen capture onto a solid support. Biotechnol. Bioeng. 2011;108: 2456–2467. © 2011 Wiley Periodicals, Inc.
Culture conditions' impact on succinate production by a high succinate producing Escherichia coli strain
Authors: Martínez Irene , Lee Amanda , Bennett George N. , San Ka‐Yiu 
Published: May 2011

AbstractThis work aimed to identify the key operational factors that significantly affect succinate production by the high succinate producing Escherichia coli strain SBS550MG (pHL413), which bears mutations inactivating genes adhE ldhA iclR
ackpta::CmR and overexpresses the pyruvate carboxylase from Lactococcus lactis. The considered factors included glucose concentration, cell density, CO2 concentration in the gas stream, pH, and temperature. The results showed that high glucose concentrations inhibited succinate production and that there is a compromise between the total succinate productivity and succinate specific productivity, where the total productivity increased with the increase in cell density and the specific productivity decreased with cell density, probably due to mass transfer limitation. On the other hand, a CO2 concentration of 100% in the gas stream showed the highest specific succinate productivity, probably by favoring pyruvate carboxylation, increasing the OAA pool that later is converted into succinate. A full factorial design of experiments was applied to analyze the pH and temperature effects on succinate production in batch bioreactors, where succinate yield was not significantly affected by either temperature (37 to 43°C) or pH (6.5 to 7.5). Additionally, the temperature effect on succinate productivity and titer was not significant, in the range tested. On the other hand, a pH of 6.5 showed very low productivity, whereas pH values of 7.0 and 7.5 resulted in significantly higher specific productivities and higher titers. The increase on pH value from 7.0 to 7.5 did not show significant improvement. Then, pH 7.0 should be chosen because it involves a lower cost in base addition. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Dual salt precipitation for the recovery of a recombinant protein from Escherichia coli
Authors: Balasundaram Bangaru , Sachdeva Soam , Bracewell Daniel G. 
Published: May 2011

AbstractWhen considering worldwide demand for biopharmaceuticals, it becomes necessary to consider alternative process strategies to improve the economics of manufacturing such molecules. To address this issue, the current study investigates precipitation to selectively isolate the product or remove contaminants and thus assist the initial purification of a intracellular protein. The hypothesis tested was that the combination of two or more precipitating agents will alter the solubility profile of the product through synergistic or antagonistic effects. This principle was investigated through several combinations of ammonium sulfate and sodium citrate at different ratios. A synergistic effect mediated by a known electrostatic interaction of citrate ions with Fab' in addition to the typical salting‐out effects was observed. On the basis of the results of the solubility studies, a two step primary recovery route was investigated. In the first step termed conditioning, post‐homogenization and before clarification, addition of 0.8 M ammonium sulfate extracted 30% additional product. Clarification performance measured using a scale‐down disc stack centrifugation mimic determined a four‐fold reduction in centrifuge size requirements. Dual salt precipitation in the second step resulted in >98% recovery of Fab' while removing 36% of the contaminant proteins simultaneously. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Representations of Attachment Patterns in the Family Drawings of Maltreated and Non‐maltreated Children
Authors: Shiakou Monica 
Published: May 2011

The study was conducted to investigate and compare the attachment styles of maltreated and non‐maltreated children through the use of the family drawing technique. The sample consisted of ten maltreated and ten non‐maltreated children between the ages of five and 11. The findings revealed that the maltreated children depicted significantly more items in their drawings linked to an insecure attachment pattern than non‐maltreated children, while the non‐maltreated children made use of significantly more drawing features linked to a secure attachment pattern. These results corresponded to scores on the Child Behaviour Checklist (Achenbach, 1991). All maltreated children scored in the clinical range. The family drawings of maltreated children significantly evidenced a greater distress − represented by an insecure attachment pattern – than the drawings of non‐maltreated children represented by a secure attachment style. Copyright © 2011 John Wiley & Sons, Ltd.‘The family drawings of maltreated children significantly evidenced a greater distress’
Extension of multiunit global optimisation to three‐input systems
Authors: Azar F. Esmaeilzadeh , Perrier M. , Srinivasan B. 
Published: May 2011

AbstractFinding the global optimum of an objective function has been of interest in many disciplines. Recently, a global optimisation technique based on multiunit extremum seeking has been proposed for scalar and two‐input systems. The idea of multiunit extremum‐seeking is to control the gradient evaluated using finite difference between two identical units operating with an offset. For scalar systems, it was shown that the global optimum could be obtained by reducing the offset to zero. For two‐input systems, the univariate global optimisation is performed on the circumference of a circle of reducing radius. In this study, the concept is extended to three‐input systems where the circle of varying radius sits on a shrinking sphere. The key contribution lies in formulating the rotation required to keep the best point found in the search domain. The theoretical concepts are illustrated on the global optimisation of several examples. Comparison results with other competitive methods show that the proposed technique performs well in terms of number of function evaluations and accuracy. © 2011 Canadian Society for Chemical Engineering