bluuebunny/crossref_metadata_2025 huggingface dataset:
Template‐Confined Dewetting Process to Surface Nanopatterns: Fabrication, Structural Tunability, and Structure‐Related Properties
Authors: Yang Shikuan , Xu Feng , Ostendorp Stefan , Wilde Gerhard , Zhao Huaping , Lei Yong
Published: May 2011

Metallic surface nanopatterns are prepared by a template‐confined dewetting process with multiple structural controllabilities. The morphology of the building blocks is homogeneous throughout the surface nanopatterns, as the dewetting process proceeds separately in each bowl. The features of the building units in the surface patterns are highly dependent on the annealing temperature. Importantly, the size and composition of the nanoparticles in the surface nanopatterns can be pre‐calculated and designed by manipulating the thickness of the evaporated metallic films. The heating temperature and composition of the building units influence the surface‐enhanced Raman scattering (SERS) and plasmonic properties, thus tuning the localized surface plasmon resonance peaks over a broad range (from visible to near infrared). The introduction of silver in the gold surface nanopatterns enhances the SERS performance dramatically. This work not only provides a powerful route to fabricate surface nanopatterns, but also supplies a platform to study the mechanism of the complicated dewetting processes of metals.
Amino Acid Pairing for De Novo Design of Self‐Assembling Peptides and Their Drug Delivery Potential
Authors: Fung Shan‐Yu , Yang Hong , Sadatmousavi Parisa , Sheng Yuebiao , Mamo Tewodros , Nazarian Reyhaneh , Chen P.
Published: May 2011

Molecular self‐assembly has emerged as the “bottom‐up” engineering route to fabricate functional supramolecules for diverse applications. The design of molecular building units becomes critical in determining the structure, properties, and function of the resulting assemblies. Here, a de novo design principle of amino acid pairing (AAP) to generate new classes of self‐assembling peptides (SAPs) is presented. In this study, the AAP focuses on hydrogen bonding, and ionic and hydrophobic interactions among amino acid pairs. With solely hydrogen bond pairs, SAPs can be constructed with only two amino acids. With all three AAP strategies (hydrogen bonds, ionic and hydrophobic pairs), a short novel SAP is constructed. This peptide can self‐assemble into β‐sheet‐rich nanofibers with a relatively low “critical aggregation concentration (CAC)” of ∼10 μM. It also shows the ability to stabilize and deliver the hydrophobic anticancer agent ellipticine in aqueous solution. The peptide‐drug complexes/co‐assemblies exhibit anticancer activity against human lung carcinoma cells A549 and breast cancer cells MCF‐7, and have good dilution stability. The presented AAP design provides a new strategy to fabricate functional supramolecules with potential applications in nanomedicine.
Array of Single‐Walled Carbon Nanotube Intrajunction Devices Fabricated via Type Conversion by Partial Coating with β‐Nicotinamide Adenine Dinucleotide
Authors: Yoon Jangyeol , Park Jaehyun , Kim Junsung , Kim Gyu Tae , Ha Jeong Sook
Published: May 2011

The fabrication of aligned single‐walled, carbon nanotube (SWCNT) intratube junction devices by partially coating pristine SWCNTs with a β‐nicotinamide adenine dinucleotide (NADH) solution and subsequent annealing at 150 °C is reported. Gate‐bias‐dependent rectification behavior is observed with a rectification ratio of >103 at ±1 V. A comparative study with p–n‐junction devices of randomly networked SWCNTs confirms the advantage of using aligned SWCNTs with substantially better rectifying characteristics due to the selective removal of metallic tubes by electrical breakdown. The gate dependence of the intratube p–n‐junction in the forward and backward directions is attributed to the difference in the shift of the Fermi levels (forward bias) and the enhanced direct tunneling (reverse bias), as suggested by band‐diagram modeling. This work suggests a potential application of aligned SWCNT intratube p–n‐junction devices in the future of nanoelectronic circuits.
Economic model predictive control of nonlinear process systems using Lyapunov techniques
Authors: Heidarinejad Mohsen , Liu Jinfeng , Christofides Panagiotis D.
Published: May 2011

In this work, we develop model predictive control (MPC) designs, which are capable of optimizing closed‐loop performance with respect to general economic considerations for a broad class of nonlinear process systems. Specifically, in the proposed designs, the economic MPC optimizes a cost function, which is related directly to desired economic considerations and is not necessarily dependent on a steady‐state—unlike conventional MPC designs. First, we consider nonlinear systems with synchronous measurement sampling and uncertain variables. The proposed economic MPC is designed via Lyapunov‐based techniques and has two different operation modes. The first operation mode corresponds to the period in which the cost function should be optimized (e.g., normal production period); and in this operation mode, the MPC maintains the closed‐loop system state within a predefined stability region and optimizes the cost function to its maximum extent. The second operation mode corresponds to operation in which the system is driven by the economic MPC to an appropriate steady‐state. In this operation mode, suitable Lyapunov‐based constraints are incorporated in the economic MPC design to guarantee that the closed‐loop system state is always bounded in the predefined stability region and is ultimately bounded in a small region containing the origin. Subsequently, we extend the results to nonlinear systems subject to asynchronous and delayed measurements and uncertain variables. Under the assumptions that there exist an upper bound on the interval between two consecutive asynchronous measurements and an upper bound on the maximum measurement delay, an economic MPC design which takes explicitly into account asynchronous and delayed measurements and enforces closed‐loop stability is proposed. All the proposed economic MPC designs are illustrated through a chemical process example and their performance and robustness are evaluated through simulations. © 2011 American Institute of Chemical Engineers AIChE J, 2012
Improving agricultural injury surveillance: A comparison of incidence and type of injury event among three data sources
Authors: Earle‐Richardson Giulia B. , Jenkins Paul L. , Scott Erika E. , May John J.
Published: May 2011

Background

Agriculture ranks as one of the most hazardous industries in the nation. Ongoing injury surveillance is key to identifying and preventing major sources of injury.

Objective

The objective of this study was to compare the total number and types of injuries identified from community reporting versus two newly available medical data systems. These new systems are important because they are less time consuming and expensive to maintain.

Method

Farm injury case records from 2007 were collected for 10 NY counties from the following sources: ambulance reports, hospital data, and community surveillance data.

Results

For the 107 ambulance report cases, horses (35%), tractors (15%), and livestock (10%) were the three leading injury sources. For the 261 hospital cases, the leading sources were hand tools (24%), farmstead machinery (23%), and buildings/structures/surfaces (22%). Tractor injuries (37%) were the most common source of injuries identified by the 44 community surveillance cases. Struck by object was the most frequent injury event type for hospital and surveillance data (34%, 30%). Falls were the highest category for ambulance reports (36%) and were also common for hospital data (29%). Nine of the 11 fatal cases were found through community surveillance.

Conclusion

Ambulance reports and hospital data contribute a large number of additional farm injury cases to existing surveillance data. From these cases, horse injuries, falls, and hand tool injuries appear to play a larger role in farm injuries. Future research should explore how to best use these electronic resources for agricultural injury surveillance. Am. J. Ind. Med. 54:586–596, 2011. © 2011 Wiley‐Liss, Inc.
Experimental field study of problem‐solving using tools in free‐ranging capuchins (Sapajus nigritus, formerlyCebus nigritus)
Authors: Garber P.A. , Gomes D.F. , Bicca‐Marques J.C.
Published: May 2011

Some populations of capuchins are reported to use tools to solve foraging problems in the wild. In most cases, this involves the act of pounding and digging. The use of probing tools by wild capuchins is considerably less common. Here we report on the results of an experimental field study conducted in southern Brazil designed to examine the ability of wild black‐horned capuchins (Sapajus nigritus) to use a wooden dowel as a lever or a probe to obtain an embedded food reward. A group of eight capuchins was presented with two experimental platforms, each housing a clear Plexiglas box containing two bananas on a shelf and four inserted dowels. Depending on the conditions of the experiment, the capuchins were required either to pull (Condition I) or push (Conditions II and III) the dowels, in order to dislodge the food reward from the shelf so that it could be manually retrieved. In Condition I, four individuals spontaneously solved the foraging problem by pulling the dowels in 25% (72/291) of visits. In Conditions II and III, however, no capuchin successfully pushed the dowels forward to obtain the food reward. During these latter two experimental conditions, the capuchins continued to pull the dowels (41/151 or 27% of visits), even though this behavior did not result in foraging success. The results of these field experiments are consistent with an identical study conducted on wildCebus capucinusin Costa Rica, and suggest that when using an external object as a probe to solve a foraging problem, individual capuchins were able to rapidly learn an association between the tool and the food reward, but failed to understand exactly how the tool functioned in accomplishing the task. The results also suggest that once a capuchin learned to solve this tool‐mediated foraging problem, the individual persisted in using the same solution even in the face of repeated failure (slow rate of learning extinction). Am. J. Primatol. 74:344–358, 2012. © 2011 Wiley Periodicals, Inc.
Validation of a cortisol enzyme immunoassay and characterization of salivary cortisol circadian rhythm in chimpanzees (Pan troglodytes)
Authors: Heintz Matthew R. , Santymire Rachel M. , Parr Lisa A. , Lonsdorf Elizabeth V.
Published: May 2011

Monitoring concentrations of stress hormones is an important tool for behavioral research and conservation for animals both in the wild and captivity. Glucocorticoids can be measured in mammals as an indicator of stress by analyzing blood, feces, urine, hair, feathers, or saliva. The advantages of using saliva for measuring cortisol concentrations are three‐fold: it is minimally invasive, multiple samples can be collected from the same individual in a short timeframe, and cortisol has a relatively short response time in saliva as compared with other materials. The purpose of this study was to: (1) conduct an adrenocorticotropic hormone (ACTH) challenge as a physiological validation for an enzyme immunoassay to measure salivary cortisol in chimpanzees and (2) characterize the circadian rhythm of salivary cortisol in chimpanzees. We determined that salivary cortisol concentrations peaked 45 min following the ACTH challenge, which is similar to humans. Also, salivary cortisol concentrations peaked early in the morning and decreased throughout the day. We recommend that saliva collection may be the most effective method of measuring stress reactivity and has the potential to complement behavioral, cognitive, physiological, and welfare studies. Am. J. Primatol. 73:903–908, 2011. © 2011 Wiley‐Liss, Inc.
Partially fluorinated polymer networks: Synthesis and structural characterization
Authors: Miccio L. A. , Liaño R. , Montemartini P. E. , Oyanguren P. A.
Published: May 2011

Functionalizacion of epoxy‐based networks by the preferential surface enrichment of perfluorinated tails to achieve hydrophobic surface is described. The selected fluorinated epoxies (FE) were: 2,2,3,3,4,4,5,5,6,6,7,7,8,9,9,9‐hexadecafluoro‐8‐trifluoromethyl nonyloxirane (FED3) and 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9‐heptadecafluoro nonyloxirane (FES3). Two series of crosslinked fluorinated epoxy‐based materials containing variable fluorine contents (from 0 to 5 wt % F) were prepared using formulations based on partially fluorinated diamine, epoxy monomer and a curing agent. The epoxy monomer was based on diglycidyl ether of bisphenol A (DGEBA) while the curing agents were either propyleneoxide diamine (JEFFAMINE) or 4,4′‐methylenebis(3‐chloro 2,6‐diethylaniline) (MCDEA). It was found that depending on the curing agent employed, homogeneous distribution of fluorine or phase separation distinguishable at micrometer or nanometer scale was obtained when curing blends initially homogeneous. The morphology and composition of partially fluorinated networks were investigated on a micrometer scale combining scanning electron microscopy and X‐ray analysis. When curing with JEFFAMINE, samples were homogeneous for all fluorine proportions. In contrast, MCDEA‐cured blends showed fluorine‐rich zones dispersed in a continuous epoxy‐rich phase. A completely different morphology, characterized by a distribution of irregular fluorine‐rich domains dispersed in an epoxy‐rich phase, was obtained when curing blends initially immiscible. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.
Contributions of angiogenesis to inflammation, joint damage, and pain in a rat model of osteoarthritis
Authors: Ashraf Sadaf , Mapp Paul I. , Walsh David A.
Published: May 2011

Objective

To determine the contributions of angiogenesis to inflammation, joint damage, and pain behavior in a rat meniscal transection model of osteoarthritis (OA).

Methods

OA was induced in male Lewis rats (n = 8 per group) by meniscal transection. Animals were orally dosed with dexamethasone (0.1 mg/kg/day), indomethacin (2 mg/kg/day), or the specific angiogenesis inhibitor PPI‐2458 (5 mg/kg every other day). Controls consisted of naive and vehicle‐treated rats. Synovial inflammation was measured as the macrophage fractional area (expressed as the percentage), thickness of the synovial lining, and joint swelling. Synovial angiogenesis was measured using the endothelial cell proliferation index and vascular density. Channels positive for vessels at the osteochondral junction were assessed (osteochondral angiogenesis). Medial tibial plateaus were assessed for chondropathy, osteophytosis, and channels crossing the osteochondral junction. Pain behavior was measured as weight‐bearing asymmetry.

Results

Dexamethasone and indomethacin each reduced pain behavior, synovial inflammation, and synovial angiogenesis 35 days after meniscal transection. Dexamethasone reduced, but indomethacin had no significant effect on, the total joint damage score. PPI‐2458 treatment reduced synovial and osteochondral angiogenesis, synovial inflammation, joint damage, and pain behavior.

Conclusion

Our findings indicate that synovial inflammation and joint damage are closely associated with pain behavior in the meniscal transection model of OA. Inhibition of angiogenesis may reduce pain behavior both by reducing synovitis and by preventing structural change. Targeting angiogenesis could therefore prove useful in reducing pain and structural damage in OA.
Optimizing sustainable feeder bus operation considering realistic networks and heterogeneous demand
Authors: DiJoseph Patricia , Chien Steven I‐Jy
Published: May 2011

A mathematical model is developed to optimize social and fiscal sustainable operation of a feeder bus system considering realistic network and heterogeneous demand. The objective total profit is a nonlinear, mixed integer function, which is maximized by optimizing the number of stops, headway, and fare. The stops are located which maximize the ridership. The demand elasticity for the bus service is dependent on passengers' access distance, wait time, in‐vehicle time, and fare. An optimization algorithm is developed to search for the optimal solution that maximizes the profit. The modeling approach is applied to planning a bus transit system within Woodbridge, New Jersey. Copyright © 2011 John Wiley & Sons, Ltd.
The sea change in US biofuels' funding: from cellulosic ethanol to green gasoline
Authors: Regalbuto J. R.
Published: May 2011

The direction of federal funding for biomass conversion into biofuels has shifted dramatically in just the last few years. Four years ago, the national action plan essentially read ‘ethanol‐only’, and was to meet the new renewable fuel standards solely with cellulosic ethanol. While ethanol is still part of the picture, the most recent emphasis is on ‘high energy density, infrastructure‐compatible biofuels’ – hydrocarbons. In this paper, the transition from one focus to the other, a real sea change, is conveyed from the perspective of one who, with the support of the NSF and colleagues in other federal agencies, helped to bring it about. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd
A double abdominal aorta with a double inferior vena cava: A human congenital vascular patterning defect
Authors: Kayhan Arda , Collins Jack , Al‐Sadir Jafar , Zhu Fang , Oto Aytekin , Svensson Eric C.
Published: May 2011

BACKGROUND

Developmental abnormalities of the abdominal aorta are exceedingly rare, and the molecular mechanisms underlying these defects are unknown.

CASE

We present computed angiographic findings of a 64‐year‐old female with long‐standing hypertension having an abdominal double aorta accompanied by a double inferior vena cava. The abdominal aorta bifurcated into two lumens just caudal to the diaphragm at the level of the 12th thoracic vertebra. The dorsal abdominal aortic trunk supplied several lumbar arteries, the inferior mesenteric artery, and both iliac arteries. The ventral abdominal aortic trunk supplied the celiac artery, both renal arteries, and the superior mesenteric artery.

CONCLUSION

We propose that a defect in the development of the aortic vascular smooth muscle is a possible mechanism for this rare anomaly based on our current understanding of the formation of the aorta during early embryonic development. Birth Defects Research (Part A), 2011. © 2011 Wiley‐Liss, Inc.
Willy Stöhr – Ein Ingenieurleben zwischen Diktatur und Demokratie
Authors: Pelke Eberhard
Published: May 2011

Der Lebensweg Willy Stöhrs (1905–1997) spiegelt exemplarisch das Verhalten vieler deutscher Ingenieure in der Zeit zwischen Nationalsozialismus und Wiederaufbau, technischer Herausforderung und politischer Repression. Am Beispiel des Spannbetons zeigt er Einfluss und Einwirkungszeit deutscher Verwaltungsingenieure auf Innovationen im Bauwesen.
Kathodischer Korrosionsschutz an Bauwerksfugen
Authors: Sodeikat Christian , Mayer Till Felix , Schöning Markus
Published: May 2011

Der 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

Der 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 structures

The 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

Im 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 Concrete

The 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

Here 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

Numerous 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

Glycosaminoglycans (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

Aptamers 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

The 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

Living 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

A 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

This 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

When 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

Finding 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
Robust polarity specification operates above a threshold of microtubule dynamicity
Authors: Thadani Rahul , Huang Daniel , Oliferenko Snezhana
Published: May 2011

Microtubule arrays effect cell polarisation by directing cellular cues for cortical remodelling and growth. Their function depends crucially on the intrinsic dynamic properties of constituent microtubules. Microtubule dynamicity is restricted to a certain range within the confines of a cellular geometry. Thus it is of great interest to determine whether rescaling of dynamic properties of microtubules has consequences for cell polarity. We constructed fission yeast strains exhibiting depressed microtubule dynamics by mutating the β‐tubulin gene, nda3. This interfered with efficient accumulation of a polarity factor Tea1 at cell tips. Interestingly, the polarity machinery in the mutant cells was highly susceptible to perturbations. Simulations of growth zone formation followed by imaging of actin distribution showed a significantly delayed onset of bipolar growth. We propose that there exists a threshold of microtubule dynamicity that allows robust cellular polarisation. © 2011 Wiley‐Liss, Inc.
Employing graphics processing unit technology, alternating direction implicit method and domain decomposition to speed up the numerical diffusion solver for the biomedical engineering research
Authors: Jiang Beini , Struthers Allan , Sun Zhe , Feng Zhuo , Zhao Xuqian , Zhao Kaiyong , Dai Weizhong , Zhou Xiaobo , Berens Michael E. , Zhang Le
Published: May 2011

Diffusion of biological compounds, including nutrients, oxygen, and chemoattractants, is a common component of biomedical engineering models. Conventional numerical schemes, such as alternating direction implicit (ADI) for diffusion, are frequently the computational bottleneck. Our study employs graphics processing unit (GPU) technology to accelerate the diffusion model simulation. We tailor, implement, analyze, and test several parallel ADI algorithms on the highly parallel computational and data architecture of the GPU. Our study confirms that the proposed algorithms provide fast, high‐quality simulation results suitable for inclusion in numerous bioengineering simulations. Copyright © 2011 John Wiley & Sons, Ltd.
Laminar‐to‐turbulent fluid–nanoparticle dynamics simulations: Model comparisons and nanoparticle‐deposition applications
Authors: Zhang Zhe , Kleinstreuer Clement
Published: May 2011

Relying on benchmark experimental data sets for flow in conduits with local constrictions, LES and three widely used RANS turbulence models, i.e. the low Reynolds number (LRN) k‐ω model, standard k‐ω model and shear stress transport (SST) transition model, were compared and evaluated to gain new physical insight and provide useful turbulence modeling information. These two geometric test cases may represent stenosed arteries and a segment of the human upper airways where the velocity fields undergo all flow regimes, i.e. from laminar, via transitional, to fully turbulent.

The comparison study revealed that the standard k‐ω models amplify the flow instabilities after the constrictions, and hence fail to capture the laminar flow behavior at relatively LRNs. The overall performances of LES, the LRN k‐ω model and SST transition model do not have measurable differences in predicting laminar flows and transition to turbulent flow, while the SST transition model may give a better prediction of turbulence kinetic energy profiles in some cases. Clearly, LES can provide instantaneous velocity fluctuations, which may be significant for turbulent micron particle transport/deposition in the respiratory tract. However, it requires 100‐fold more computational time than RANS turbulence models. The use of different turbulence models has a minor effect on nanoparticle deposition in human upper airways when the inspiratory flow rate is low, say, Q = 10L/min. The relative difference for deposition fraction (DF) of nanoparticles with dp>10nm is measurable at a medium inhalation flow rate (say, Q = 30L/min) when employing different turbulence models. However, the absolute difference in DFs is within 0.5% for all‐sized nanoparticles (i.e. 1nm⩽dp⩽50nm) because the DF in the oral airway is very low (say, <1.5%) when 10 nm and 10 L/min.

The modeling and simulation information provided are most useful for computational fluid–particle dynamics practitioners to obtain accurate lung deposition concentrations of inhaled toxic or therapeutic nanoparticles. The physical insight provided sheds additional light on the laminar‐to‐turbulent airflow and nanoparticle transport/deposition in locally constricted conduits. Copyright © 2011 John Wiley & Sons, Ltd.
Universality and extremal aging for dynamics of spin glasses on subexponential time scales
Authors: Ben Arous Gérard , Gün Onur
Published: May 2011

We consider random hopping time (RHT) dynamics of the Sherrington‐Kirkpatrick (SK) model and p‐spin models of spin glasses. For any of these models and for any inverse temperature β > 0 we prove that, on time scales that are subexponential in the dimension, the properly scaled clock process (time‐change process) of the dynamics converges to an extremal process. Moreover, on these time scales, the system exhibits aging‐like behavior, which we call extremal aging. In other words, the dynamics of these models ages as the random energy model (REM) does. Hence, by extension, this confirms Bouchaud's REM‐like trap model as a universal aging mechanism for a wide range of systems that, for the first time, includes the SK model. © 2011 Wiley Periodicals, Inc.