bluuebunny/crossref_metadata_2025 huggingface dataset:
Arsenic‐Mediated Activation of the Nrf2‐Keap1 Antioxidant Pathway
Authors: Lau Alexandria , Whitman Samantha A. , Jaramillo Melba C. , Zhang Donna D.
Published: November 2012

Arsenic is present in the environment and has become a worldwide health concern due to its toxicity and carcinogenicity. However, the specific mechanism(s) by which arsenic elicits its toxic effects has yet to be fully elucidated. The transcription factor nuclear factor (erythroid‐derived 2)‐like 2 (Nrf2) has been recognized as the master regulator of a cellular defense mechanism against toxic insults. This review highlights studies demonstrating that arsenic activates the Nrf2‐Keap1 antioxidant pathway by a distinct mechanism from that of natural compounds such as sulforaphane (SF) found in broccoli sprouts or tert‐butylhyrdoquinone (tBHQ), a natural antioxidant commonly used as a food preservative. Evidence also suggests that arsenic prolongs Nrf2 activation and may mimic constitutive activation of Nrf2, which has been found in several human cancers due to disruption of the Nrf2‐Keap1 axis. The current literature strongly suggests that activation of Nrf2 by arsenic potentially contributes to, rather than protects against, arsenic toxicity and carcinogenicity. The mechanism(s) by which known Nrf2 activators, such as the natural chemopreventive compounds SF and lipoic acid, protect against the deleterious effects caused by arsenic will also be discussed. These findings will provide insight to further understand how arsenic promotes a prolonged Nrf2 response, which will lead to the identification of novel molecular markers and development of rational therapies for the prevention or intervention of arsenic‐induced diseases.

The National Institute of Environmental Health Science (NIEHS) Outstanding New Environmental Scientist (ONES) award has provided the opportunity to review the progress both in the fields of arsenic toxicology and Nrf2 biology. Much of the funding has led to (1) the novel discovery that arsenic activates the Nrf2 pathway by a mechanism different to that of other Nrf2 activators, such as sulforaphane and tert‐butylhydroquinone, (2) activation of Nrf2 by chemopreventive compounds protects against arsenic toxicity and carcinogenicity both in vitro and in vivo, (3) constitutive activation of Nrf2 by disrupting Keap1‐mediated negative regulation contributes to cancer and chemoresistance, (4) p62‐mediated sequestration of Keap1 activates the Nrf2 pathway, and (5) arsenic‐mediated Nrf2 activation may be through a p62‐dependent mechanism. All of these findings have been published and are discussed in this review. This award has laid the foundation for my laboratory to further investigate the molecular mechanism(s) that regulate the Nrf2 pathway and how it may play an integral role in arsenic toxicity. Moreover, understanding the biology behind arsenic toxicity and carcinogenicity will help in the discovery of potential strategies to prevent or control arsenic‐mediated adverse effects. © 2012 Wiley Periodicals, Inc. J BiochemMol Toxicol 27:99‐105, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.21463
Recent advances in microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) for wastewater treatment, bioenergy and bioproducts
Authors: Zhou Minghua , Wang Hongyu , Hassett Daniel J. , Gu Tingyue
Published: November 2012

Bioenergy is a renewable energy that plays an indispensable role in meeting today's ever increasing energy needs. Unlike biofuels, microbial fuel cells (MFCs) convert energy harvested from redox reactions directly into bioelectricity. MFCs can utilize low‐grade organic carbons (fuels) in waste streams. The oxidation of the fuel molecules requires biofilm catalysis. In recent years, MFCs have also been used in the electrolysis mode to produce bioproducts in laboratory tests. MFCs research has intensified in the past decade and the maximum MFCs power density output has been increased greatly and many types of waste streams have been tested. However, new breakthroughs are needed for MFCs to be practical in wastewater treatment and power generation beyond powering small sensor devices. To reduce capital and operational costs, simple and robust membrane‐less MFCs reactors are desired, but these reactors require highly efficient biofilms. Newly discovered conductive cell aggregates, improved electron transport through hyperpilation via mutation or genetic recombination and other advances in biofilm engineering present opportunities. This review is an update on the recent advances on MFCs designs and operations. © 2012 Society of Chemical Industry
Comparison of contrast‐enhanced multi‐station MR angiography and digital subtraction angiography of the lower extremity arterial disease
Authors: Burbelko Mykhaylo , Augsten Michael , Kalinowski Marc O. , Heverhagen Johannes T.
Published: November 2012

Purpose:

To compare diagnostic accuracy of multi‐station, high‐spatial resolution contrast‐enhanced MR angiography (CE‐MRA) of the lower extremities with digital subtraction angiography (DSA) as the reference standard in patients with symptomatic peripheral arterial occlusive disease.

Materials and Methods:

Of 485 consecutive patients undergoing a run‐off CE‐MRA, 152 patients (86 male, 66 female; mean age, 71.6 years) with suspected peripheral arterial occlusive disease were included into our Institutional Review Board approved study. All patients underwent MRA and DSA of the lower extremities within 30 days. MRA was performed at 1.5 Tesla with a single bolus of 0.1 mmol/kg body weight of gadobutrol administered at a rate of 2.0 mL/s at three stations. Two readers evaluated the MRA images independently for stenosis grade and image quality. Sensitivity and specificity were derived.

Results:

Sensitivity and specificity ranged from 73% to 93% and 64% to 89% and were highest in the thigh area. Both readers showed comparable results. Evaluation of good and better quality MRAs resulted in a considerable improvement in diagnostic accuracy.

Conclusion:

Contrast‐enhanced MRA demonstrates good sensitivity and specificity in the investigation of the vasculature of the lower extremities. While a minor investigator experience dependence remains, it is standardizable and shows good inter‐observer agreement. Our results confirm that the administration of Gadobutrol at a standard dose of 0.1 mmol/kg for contrast‐enhanced runoff MRA is able to detect hemodynamically relevant stenoses. Use of contrast‐enhanced MRA as an alternative to intra‐arterial DSA in the evaluation and therapeutic planning of patients with suspected peripheral arterial occlusive disease is well justified. J. Magn. Reson. Imaging 2013;37:1427–1435. © 2012 Wiley Periodicals, Inc.
Pentoxifylline and propentofylline prevent proliferation and activation of the mammalian target of rapamycin and mitogen activated protein kinase in cultured spinal astrocytes
Authors: Norsted Gregory Ebba , Delaney Ada , AbdelMoaty Sally , Bas Duygu B. , Codeluppi Simone , Wigerblad Gustaf , Svensson Camilla I.
Published: November 2012

Astrocyte activation is an important feature in many disorders of the central nervous system, including chronic pain conditions. Activation of astrocytes is characterized by a change in morphology, including hypertrophy and increased size of processes, proliferation, and an increased production of proinflammatory mediators. The xanthine derivatives pentoxifylline and propentofylline are commonly used experimentally as glial inhibitors. These compounds are generally believed to attenuate glial activity by raising cyclic AMP (cAMP) levels and inhibiting glial tumor necrosis factor (TNF) production. In the present study, we show that these substances inhibit TNF and serum‐induced astrocyte proliferation and signaling through the mammalian target of rapamycin (mTOR) pathway, demonstrated by decreased levels of phosphorylated S6 kinase (S6K), commonly used as a marker of mTOR complex (mTORC) activation. Furthermore, we show that pentoxifylline and propentofylline also inhibit JNK and p38, but not ERK, activation induced by TNF. In addition, the JNK antagonist SP600125, but not the p38 inhibitor SB203580, prevents TNF‐induced activation of S6 kinase, suggesting that pentoxifylline and propentofylline may regulate mTORC activity in spinal astrocytes partially through inhibition of the JNK pathway. Our results suggest that pentoxifylline and propentofylline inhibit astrocyte activity in a broad fashion by attenuating flux through specific pathways. © 2012 Wiley Periodicals, Inc.
Lipidome and proteome map of myelin membranes
Authors: Gopalakrishnan Gopakumar , Awasthi Anshul , Belkaid Wiam , De Faria Omar , Liazoghli Dalinda , Colman David R. , Dhaunchak Ajit S.
Published: November 2012

To understand the molecular anatomy of myelin membranes, we performed a large‐scale, liquid chromatography‐coupled tandem mass spectrometry (LC‐MS/MS)‐based lipidome and proteome screen on freshly purified human and murine myelin fractions. We identified more than 700 lipid moieties and above 1,000 proteins in the two species, including 284 common lipids and 257 common proteins. This study establishes the first comprehensive map of myelin membrane components in human and mice. Although this study demonstrates many similarities between human and murine myelin, several components have been identified exclusively in each species. Future quantitative validation studies focused on interspecies differences will authenticate the myelin membrane anatomy. The combined lipidome and proteome map presented here can nevertheless be used as a reference library for myelin health and disease. © 2012 Wiley Periodicals, Inc.
Environmental enrichment upregulates micro‐RNA‐183 and alters acetylcholinesterase splice variants to reduce anxiety‐like behavior in the little Indian field mouse (Mus booduga)
Authors: Ragu Varman Durairaj , Marimuthu Ganapathy , Emmanuvel Rajan Koilmani
Published: November 2012

Environmental enrichment (EE) has an influential role in reducing behavioral reactivity to stress. We previously observed that EE reduces the anxiety‐like behavior in the field mouse Mus booduga accompanied by a reduction in the expression of molecules involved in the stress pathway. In this study, we demonstrate the effect of different housing condition on regulation of micro‐RNA‐183‐SC35‐mediated splicing of acetylcholinesterase (AChE). Adult male M. booduga were captured from an agricultural field and housed under nonenriched standard conditions (SC) for 7 days and considered as directly from the wild (DW). On day 8, individuals were randomly assigned to three groups; DW, SC, and EE. The DW group's anxiety‐like behavior was assessed in the elevated plus maze (EPM) and open field test (OFT). The SC and EE groups were transferred to their respective conditions and housed for another 30 days. The mice housed in EE showed less anxiety‐like behavior on EPM and in OFT compared with DW and SC mice. Interestingly, miR‐183 expression was increased following exposure to EPM in EE mice but not in SC mice. Subsequently, the upregulated miR‐183 expression suppresses the SC35 expression and shifting of splicing from AChE‐S (synaptic) to AChE‐R (read‐through) form, whereas standard housing condition downregulate miR‐183 and induces the splicing of AChE. The upregulated AChE‐R form possibly terminates ACh transmission, which is reflected in the level of anxiety‐like behavior. Overall, the present study suggests that EE effectively regulates the miR‐183 pathway to reduce anxiety‐like behavior. © 2012 Wiley Periodicals, Inc.
Developing microfinance: A survey of the literature
Authors: Milana Carlo , Ashta Arvind
Published: November 2012

Most contributions in the fast‐growing literature on microfinance seem to agree that all the stakeholders (borrowers, lenders, communities, government and regulators, interested third parties) should become fully aware of the potentiality of the joint value creation achieved through cooperation.
How to deal with a default tsunami in the microfinance industry: Lessons from Grameen Bank
Authors: Dowla Asif
Published: November 2012

If the reorganization is done right, the institution will come out of near death and become stronger and more effective as happened in the case of Grameen Bank.
Financing sustainable micro‐lending in London
Authors: Hannam Mark , Cheng Paul
Published: November 2012

A capital‐raising deal for London‐based micro‐lender demonstrates how it is possible to make unsecured loans to financially excluded individuals in London.
Book review: The Price of Fish. A New Approach to Wicked Economics and Better Decisions
Authors: Nadeau Pierre
Published: November 2012

Michael Minelli and Ian Harris, The Price of Fish. A New Approach to Wicked Economics and Better Decisions, Nicholas Brealey Publishing, London, 2011, ISBN 978‐1‐85788‐571‐2, £20.00, 338 pages.
Acknowledgment: Ad Hoc Reviewers
Authors: Phillips Lawrence H
Published: November 2012

As we complete another volume of the journal, it is again time to express my gratitude to all of
the individuals who have volunteered their time and expertise to serve as peer reviewers. These
colleagues have reviewed papers of the past 6 months, and I hope that the list that follows is
complete. We have called on some of these individuals multiple times to do reviews, and I am
impressed that the reviews are thorough, thoughtful, and helpful to the authors (and the
editors). Authors frequently express gratitude to the reviewers for their suggestions that have
improved the clarity and accuracy of their papers, and I know that I frequently learn from the
reviews. On behalf of all of the editorial staff, I thank each of the individuals on the list for
helping to improve the journal.
View combination in recognition of 3‐D virtual reality layouts
Authors: Zhang Hui , Friedman Alinda , Mou Weimin , Waller David
Published: November 2012

We investigated whether a normalization model or view combination model fit the performance of scene recognition of 3‐D layouts using a virtual‐reality paradigm. Participants learned a layout of seven objects from two training views (e.g., 0° and 48°) by discriminating the “correct” layout from distracters. Later, they performed a discrimination task using the training views (e.g., 0° and 48°), an interpolated view (e.g., 24°), an extrapolated view (e.g., 72°), and a far view (e.g., 96°). The results showed that the interpolated view was easier to discriminate than the extrapolated view and even easier than the training views. These results extend the applicability of view combination accounts of recognition to 3‐D stimuli with stereoscopic depth information.
Electrically conducting biodegradable polymer composites (polylactide‐polypyrrole and polycaprolactone‐polypyrrole) for passive resonant circuits
Authors: Boutry Clémentine M. , Gerber‐Hörler Isabel , Hierold Christofer
Published: November 2012

Electrically conducting biodegradable polymer composites made of polypyrrole (PPy) nanoparticles embedded in poly(L‐lactide) (PLLA) or poly(ε‐caprolactone) (PCL) are prepared by chemical oxidative polymerization. They will be used as electrical conductors for fabricating biodegradable passive resonant circuits for bioimplants. For both composites, the conductivity exhibits a percolation threshold at ∼6 wt% of PPy. Several reactants are tested, the polymerization process resulting in the highest conductivity uses iron(III)chloride hexahydrate (FeCl3), sodium dodecyl benzene sulfonate, and p‐nitrophenol (pNPh), for both poly(L‐lactide)‐polypyrrole (PLLA‐PPy) and poly(ε‐caprolactone)‐polypyrrole (PCL‐PPy). Conductivities of 2.7 ± 0.8 S cmε1 (PLLA‐PPy) and 7.8 ± 2.3 S cm−1 (PCL‐PPy) are reached for a PPy content of 40 wt%. The PPy particle, observed by SEM, forms agglomerates having a size of 0.6–3.5 μm. The samples have similar PPy particle distributions over the entire cross sections. The conductivity as a function of time is investigated, being 34–70% of the initial value for samples stored in nitrogen, whereas it is less than 1% for samples stored in body‐like conditions, bringing the conclusion that a biodegradable packaging will be required to protect the resonant circuits from body fluids. Finally, the biocompatibility of the polymer composites is evaluated with cytocompatibility tests on dermal human fibroblast cells, showing promising results in particular for composites having a low PPy content. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Experimental investigation of the effect of residual stresses on rapid crack propagation in polyethylene (PE100) pipes
Authors: Guevara‐Morales Andrea , Leevers Patrick
Published: November 2012

Pipe extruded from polyethylene of strength class PE100 was tested using the ISO 13477 Small Scale Steady State “S4” method, to investigate the effect of frozen‐in stress on rapid crack propagation (RCP). It was found that the lower the residual stress, the lower the S4 critical temperature TcS4 for RCP. Different experimental thermal treatments were used to independently modify residual stresses and crystallinity, to study the separate effects on RCP. It was found that the effect of crystallinity was less significant than that of residual stresses. It has previously been suggested that the residual stress influence on TcS4 is determined by the balance of two mechanisms: additional stored strain energy prior to fracture helps to drive the crack, while the closing moment after fracture helps to close the flaring pipe wall. Tests on annealed specimens suggested that the first effect dominates, especially soon after crack initiation. However, the observed effect seems too large to be explained by this mechanism, and we suggest that the observed benefit from annealing may be better explained by a change in crack front shape. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Study on glass transition temperature and mechanical properties of cadmium sulfide/polystyrene nanocomposites
Authors: Agarwal Sonalika , Patidar Dinesh , Saxena N.S.
Published: November 2012

The cadmium sulfide/polystyrene (CdS/PS) nanocomposites with concentration (0, 2, 4, 6, and 8) wt% of CdS nanoparticles were prepared by solution casting method and characterized through fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) measurements. The particle size of nanoparticles is found to be around 15 nm. Glass transition and mechanical behavior of CdS/PS nanocomposites were investigated using dynamic mechanical analyzer (DMA). The mechanical properties such as Young's modulus and tensile strength were determined at room, as well as at elevated temperatures through their stress–strain curves. The result shows that glass transition temperature (Tg) is shifted toward the higher temperature after the addition of CdS nanoparticles. The mechanical properties increased at low wt% loading of CdS nanoparticles and decreased for higher wt% loading of CdS nanoparticles. It was also found that mechanical properties decline with increase in the temperature. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Flow instabilities in rheotens experiments: Analysis of the impacts of the process conditions through neural network modeling
Authors: Tronci Stefania , Coppola Salvatore , Bacchelli Fabio , Grosso Massimiliano
Published: November 2012

Fiber spinning experiments are conducted with a capillary rheometer and a Rheotens tester on linear styrene‐isoprene‐styrene copolymer samples by varying extrusion temperature and drawdown velocity in a wide range of values, also covering the occurrence of instability phenomena. Tensile stress is measured during the experiences, and the experimental time series are then analyzed by means of a new methodology. The proposed approach is based on Neural Network modeling of the time series, coupled with Principal Component Analysis postprocessing of the results. The methodology is able to identify and quantify the effects of process condition on the dynamical behavior of the system. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Synthesis, characterization, biological activity, and thermal stability of new styrenic polymer having pendant ketone and its some derivatives
Authors: Erol Ibrahim , Şahin Zehra , Özcan Levent
Published: November 2012

A new type of styrene monomer, 1‐{4‐[(4‐vinylbenzyl)oxy]phenyl}ethanone (VBOPE), was synthesized. The oxime, phenylhydrazone, toluol‐4‐sulfonic acid hydrazone, and thiosemicarbazone (TSC) derivatives of VBOPE were prepared with hydroxylamine hydrochloride, phenylhydrazine, toluol‐4‐sulfonic acid hydrazine, and TSC hydrochloride, respectively. Radical homopolymerization of the monomers were prepared at 65°C in 1,4‐dioxane solution with benzoylperoxide as an initiator. The compounds was characterized with Fourier transform infrared and NMR techniques. The thermal properties of polymers were investigated with thermogravimetric analysis and differential scanning calorimetry. The activation energies of the thermal degradation of the polymers were calculated with the Ozawa and Kissinger method. The antibacterial and antifungal effects of the monomer and the polymer and its derivatives were also investigated on various bacteria and fungi. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Chiral and water‐soluble poly(2‐oxazoline)s
Authors: Luxenhofer Robert , Huber Stephan , Hytry Julia , Tong Jing , Kabanov Alexander V. , Jordan Rainer
Published: November 2012

We describe the synthesis and characterization of the first water‐soluble and chiral poly(2,4‐disubstituted‐2‐oxazoline)s. While poly(2,4‐dimethyl‐2‐oxazoline)s are water soluble up to 100 °C, aqueous solutions of poly(2‐ethyl‐4‐methly‐2‐oxazoline) exhibit a lower critical solution temperature. This is discussed in context with its constitutional isomers poly(2‐oxazoline)s and poly(2‐oxazine)s. Circular dichroism spectroscopy revealed strong Cotton effects, which are also responsive to temperature in aqueous solution. It is therefore hypothesized that structures, comparable to polyproline helices, are formed in aqueous solution. In contrast to polyproline, poly(2,4‐disubstituted‐2‐oxazoline)s are highly water soluble and therefore represent very interesting pseudo‐polypeptides that may be useful to develop responsive biomimetic biomaterials. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Donor–acceptor‐integrated conjugated polymers based on carbazole[3,4‐c:5,6‐c]bis[1,2,5]thiadiazole with tight π–π stacking for photovoltaics
Authors: Zha Daijun , Chen Lie , Wu Feiyan , Wang Hongming , Chen Yiwang
Published: November 2012

An original strategy to construct a new donor–acceptor (D–A)‐integrated structure by directly imposing “pull” unit on the “push” moiety to form fused ring architecture has been developed, and poly{N‐alkyl‐carbazole[3,4‐c:5,6‐c]bis[1,2,5]thiadiazole‐alt‐thiophene} (PCBTT) with D–A‐integrated structure, in which two 1,2,5‐thiadiazole rings are fixed on carbazole in 3‐, 4‐ and 5‐, 6‐position symmetrically and thiophene is used as bridge, has been synthesized. The interaction between pull and push units has fine tuned the HOMO/LUMO energy levels, and the resulting copolymer covers the solar flux from 300 to 750 nm. The interaction between pull and push units is worth noting that due to the fused five rings inducing strong intermolecular interaction, an extremely short π–π stacking distance of 0.32 nm has been achieved for PCBTT both in powder and solid states. This is the shortest π–π stacking distance reported for conjugated polymers. Additionally, an obvious intramolecular charge transfer and energy transfer from donor units to acceptor units have been detected in this D–A integration. A moderate‐to‐high open‐circuit voltage of ∼0.7 V in PCBTT:[6,6]‐phenyl‐C61 butyric acid methyl ester (PCBM) (w/w = 1/2) solar cells is achieved due to the low‐lying HOMO energy level of PCBTT. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Photo and electrically switchable behavior of azobenzene containing pendant bent‐core liquid crystalline polymers
Authors: Srinivasan M. Vijay , Kannan P. , Roy A.
Published: November 2012

New class of photo and electrically switchable azobenzene containing pendant bent‐core liquid crystalline monomers (AZBM 1, 2, and 3) and their polymers (AZBP 1, 2, and 3) are reported. The synthesized precursors, monomers, and polymers were characterized by FT‐IR, 1H, and 13C NMR spectroscopy. Thermal stability of polymers was examined by thermogravimetric analysis and revealed stable up to 260 °C. The mesophase transition of monomers and polymers are observed through polarized optical microscopy (POM) and further confirmed by differential scanning calorimetry (DSC). The electrically switching property of monomers and their polymers were studied by electro‐optical method. Among the three monomers AZBM 1, 2, and 3, AZBM 1 and 2 exhibit antiferroelectric (AF) switching and AZBM 3 exhibits ferroelectric (F) switching behavior. On the other hand, low molecular weight polymers (AZMP 1, 2, and 3) show weak AF and F switching behavior. The photo‐switching properties of bent‐core azo polymers are investigated using UV‐vis spectroscopy, trans to cis isomerization occurs around 25 s for AZBP‐1 and 30 s for AZBP‐2 and 3 in chloroform, whereas reverse processes take place around 80 and 90 s. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Hydrophilic polyisophthalamides containing poly(ethylene oxide) side chains: Synthesis, characterization, and physical properties
Authors: Carretero Paula , Molina Serena , Sandín Ricardo , Rodríguez‐Hernández Juan , Lozano Angel E. , Abajo Javier de
Published: November 2012

Novel polyisophthalamides containing pendent poly(ethylene oxide) (PEO) sequences were prepared by grafting PEO onto poly(5‐hydroxy‐isophthalamide)s (HO‐PIPAs). First, an optimized method of synthesis was applied to prepare HO‐PIPAs, following the rules of the direct polyamidation reaction promoted by triphenyl phosphite and catalyzed by pyridine. Next, the modification of HO‐PIPAs was performed by a nucleophilic substitution reaction with chlorine‐terminated PEO monomethyl ether of average molecular weight 100, 550, and 1000 g/mol. The modification (grafting) reaction was optimized to assure virtually 100% yield. Polymers behaved as graft or brush‐like copolymers of polyisophthalamide (PIPA) and PEO, covering a wide range of ratios of PIPA/PEO. Physical properties, such as solubility, glass transition temperature, and thermal resistance were determined. Special attention was paid to the affinity of the novel copolymers for water. It was realized that with a high content of PEO, the materials could absorb water in amounts exceeding their own weight. Gravimetric methods and water contact angle measurements were used to quantify the hydrophilicity of the current PIPA‐g‐PEO copolymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Introducing a new triazoloquinoxaline‐based fluorene copolymer for organic photovoltaics: Synthesis, characterization, and photovoltaic properties
Authors: Baran Derya , Pasker Felix M. , Blanc Stephan Le , Schnakenburg Gregor , Ameri Tayebeh , Höger Sigurd , Brabec Christoph J.
Published: November 2012

A new donor‐acceptor copolymer consisting of triazoloquinoxaline and 9,9‐dialkylfluorene units on the main chain has been synthesized, characterized and evaluated as donor material in bulk heterojunction solar cells using PC61BM as an acceptor. The resulting polymer PTQF showed good thermal stability and solubility in common organic solvents. Cyclic Voltammetry measurements showed that the PTQF has HOMO–LUMO energy levels of −5.13 and −3.62 eV, respectively. DFT calculations revealed that the HOMO is delocalized all over the thiophene and fluorene units and the LUMO is localized mainly on the triazole and pyrazine units. PTQF absorbs broadly in the visible region and exhibits a bandgap of 1.4 eV. Photovoltaic devices exhibited 1.7% efficiency for 1:2 PTQF:PC61BM blend ratio using Ca/Ag electrodes. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Photocaged pendent thiol polymer brush surfaces for postpolymerization modifications via thiol‐click chemistry
Authors: Hensarling Ryan M. , Hoff Emily A. , LeBlanc Arthur P. , Guo Wei , Rahane Santosh B. , Patton Derek L.
Published: November 2012

In this work, a postpolymerization surface modification approach is reported that provides pendent thiol functionality along the polymer brush backbone using the photolabile protection chemistry of both o‐nitrobenzyl and p‐methoxyphenacyl thioethers. Poly(2‐hydroxyethyl methacrylate) (pHEMA) brushes were synthesized via surface‐initiated atom transfer radical polymerization, after which the pHEMA hydroxyl groups were esterified with 3‐(2‐nitrobenzylthio)propanoic acid or 3‐(2‐(4‐methoxyphenyl)‐2‐oxoethylthio)propanoic acid to provide the photolabile protected pendent thiols. Addressing the protecting groups with light not only affords spatial control of reactive thiol functionality but enables a plethora of thiol‐mediated transformations with isocyanates and maleimides providing a modular route to create functional polymer surfaces. This concept was extended to block copolymer brush architectures enabling the modification of the chemical functionality of both the inner and outer blocks of the block copolymer surface. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Flexible active matrix addressed displays manufactured by printing and coating techniques
Authors: Kawahara Jun , Andersson Ersman Peter , Nilsson David , Katoh Kazuya , Nakata Yasukazu , Sandberg Mats , Nilsson Marie , Gustafsson Göran , Berggren Magnus
Published: November 2012

A flexible electrochromic active matrix addressed display, including 8 × 8 pixels, is demonstrated by using solution processing based on standard printing and coating manufacturing techniques. Each organic electrochromic display (OECD) pixel and its corresponding organic electrochemical transistor (OECT) are located on different sides of the flexible PET substrate. Electronic vias generated through the plastic substrate connects each OECD pixel with one addressing OECT. When comparing this display with actively addressed OECDs with all its components located on the same side, the present approach based on this electronic via substrate provides an enhanced pixel resolution and a relatively more simplified manufacturing process. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Comparison of two types of vertically aligned ZnO NRs for highly efficient polymer solar cells
Authors: Gonzalez‐Valls Irene , Angmo Dechan , Gevorgyan Suren A. , Sebastián Reparaz Juan , Krebs Frederik C. , Lira‐Cantu Monica
Published: November 2012

Vertically aligned ZnO nanorods (NR) are prepared by two different syntheses methods and applied on polymer solar cells (PSCs). The ZnO electrodes work as the electron transport layer with the P3HT:PCBM blend acting as the active material. Several organic blend solution conditions are optimized: concentration, solvent, and deposition speed. The effect of different NR electrode morphologies is analyzed on the solar cell performance and characterized by current–voltage curves and IPCE analyses. The photovoltaic performance of the solar cells was observed to be influenced by many factors, among them infiltration of the organic P3HT:PCBM blend within the ZnO NR layer. The infiltration of the active layer was monitored by cross section SEM and energy dispersive X‐ray spectroscopy analyses. Our results show that higher power conversion efficiencies are achieved when shorter NRs lengths are applied. The best power conversion efficiency obtained was 2.0% for a 400 nm ZnO NR electrode. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Monte‐carlo simulations of the order–disorder transition depression in ABA triblock copolymers with a short terminal block
Authors: Woloszczuk S. , Banaszak M. , Spontak R. J.
Published: November 2012

Although most ABA triblock copolymers are molecularly symmetric (i.e., the terminal blocks possess the same mass), molecularly asymmetric A1BA2 triblock copolymers are of greater fundamental interest in that they can be used to explore the transition from diblock to triblock copolymer in systematic fashion. In this study, we use a lattice Monte Carlo method known as the cooperative motion algorithm to simulate molten ABA triblock copolymers possessing a short terminal block to explore the effect of molecular asymmetry on the copolymer order–disorder transition (ODT). Reduced ODT temperatures, discerned by simultaneously analyzing several features of the simulation results, are found to compare favorably with experimental data. Of particular interest here is the initial depression in the ODT temperature for A1BA2 copolymers possessing a relatively short terminal (A2) block. This signature feature is successfully captured by the simulations and is found to be strongly dependent on composition, but weakly dependent on copolymer chain length. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Polyvinylidene fluoride‐co‐chlorotrifluoroethylene and polyvinylidene fluoride‐co‐hexafluoropropylene nanofiber‐coated polypropylene microporous battery separator membranes
Authors: Lee Hun , Alcoutlabi Mataz , Watson Jill V. , Zhang Xiangwu
Published: November 2012

Nanofiber‐coated polypropylene (PP) separator membranes were prepared by coating a Celgard® microporous PP membrane with electrospun polyvinylidene fluoride‐co‐chlorotrifluoroethylene (PVDF‐co‐CTFE) and PVDF‐co‐CTFE/polyvinylidene fluoride‐co‐hexafluoropropylene (PVDF‐co‐HFP) nanofibers. Three PVDF polymer solutions of varying compositions were used in the preparation of the nanofiber coatings. Two of the polymer solutions were PVDF‐co‐CTFE blends made using different types of PVDF‐co‐HFP copolymers. The PVDF‐co‐CTFE and PVDF‐co‐CTFE/PVDF‐co‐HFP blend nanofiber coatings have been found to have comparable adhesion to the PP microporous membrane substrate. The electrolyte uptakes and separator–electrode adhesion properties of nanofiber‐coated membranes were evaluated. Both the electrolyte uptake and the separator–electrode adhesion were improved by the nanofiber coatings. The improvement in electrolyte update capacity is not only related to the gelation capability of the PVDF copolymer nanofibers, but also attributed to the increased porosity and capillary effect on nanofibrous structure of the electrospun nanofiber coatings. Enhancement of the separator–electrode adhesion was owing to the adhesion properties of the copolymer nanofiber coatings. Compared with the PVDF‐co‐CTFE/PVDF‐co‐HFP blend nanofiber coatings studied, the PVDF‐co‐CTFE coating was more effective in improving the electrolyte uptake and separator–electrode adhesion. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Life‐Cycle Assessment of Ammunition Demilitarization in a Static Kiln
Authors: Ferreira Carlos , Ribeiro José , Mendes Ricardo , Freire Fausto
Published: November 2012

The demilitarization of ammunition that has reached the end of life (or become obsolete) has to be carried out with minimum energy and environmental impacts. The Portuguese Armed Forces have significant amounts of ammunition that need to be eliminated. In order to assess and improve ammunition demilitarization, a life‐cycle approach must be adopted. The main goal of this article is to present a comprehensive life‐cycle assessment (LCA) of the ammunition demilitarization performed by the Portuguese company IDD (Industria de Desmilitarização e Defesa). A life‐cycle model was developed for the entire demilitarization process, which involves ammunition dismantling, discharging, the incineration of energetic material, and the subsequent flue gas treatment. A detailed inventory was based on data collected from the IDD. A life‐cycle impact assessment was carried out, based on three complementary methods used to assess a total of ten impact categories: cumulative energy demand (primary energy); CML 2001 (six environmental impact categories) and USEtox (three toxicological categories). The results show that the main contributor in nine out of the ten impact categories is the incineration and gas treatment process, due to the high energy requirements (electricity and propane). Nevertheless, equipment manufacture also has a significant impact in the Human Toxicity (non‐cancer) category, mainly related to the manufacture of the static kiln. These findings enhance our understanding of demilitarization using a static kiln, showing that the associated impacts are significant and should be reduced.
Structural Characterization of RDX‐Based Explosive Nanocomposites
Authors: Stepanov Victor , Willey Trevor M. , Ilavsky Jan , Gelb Jeff , Qiu Hongwei
Published: November 2012

Recently developed cyclotrimethylene trinitramine (RDX)‐based nanostructured explosive compositions were shown to exhibit greatly reduced initiation sensitivity as compared to conventional compositions prepared with coarser, micrometer‐scale RDX. In particular, improvements were shown in the sensitivity towards shock and impact stimuli, key sources of inadvertent initiation. Such an improved response to mechanical stimuli is believed to be largely a result of smaller crystal and void sizes. Characterization of these structural parameters is therefore necessary in order to construct a meaningful physical description of these novel explosive compositions. Herein, we report the results of a detailed structural characterization of these novel RDX‐based nanocomposites. The analyzed specimens were in pellet form with nominally 10 % porosity. These results constitute an unprecedentedly complete structural picture of this new class of energetic materials.
Bioimpedance for Oedema Evaluation after Total Knee Arthroplasty
Authors: Pichonnaz Claude , Bassin Jean‐Philippe , Currat Damien , Martin Estelle , Jolles Brigitte M.
Published: November 2012

Background and Purpose

Electrical bioimpedance spectroscopy (BIS) allows the evaluation of limb extracellular fluid (R0) and total fluid (Rinf). BIS could facilitate post‐surgical oedema evaluation after total knee arthroplasty (TKA), as it is easily performed and is non‐invasive. However, neither its applicability in this context nor the influence of metallic implants on measurement has been evaluated. The aim of this study was to evaluate the influence of TKA implants on the BIS R0 and Rinf variables used for oedema evaluation.

Method

This was a prospective non‐randomized comparative clinical trial. One oedema‐free group of patients with TKA was compared with a group presenting similar characteristics except for the arthroplasty, to assess the influence of the implant on BIS measurement in the absence of oedema. The TKA group included 15 patients who had undergone surgery more than a year previously, and the control group included 19 patients awaiting TKA surgery. Volume and perimeter measurements served as reference criterions. The lower limb percentage differences for BIS, knee perimeter and volume were calculated. The significance of differences between groups was calculated for all measurement methods, using the Mann–Whitney test. The setting was a Department of Orthopedic Surgery and Traumatology in a university hospital.

Results

The differences between groups were not significant for R0, Rinf, volume and perimeter. R0 showed the smallest mean difference in limb percentage difference between groups [means (SD): TKA 3.98 (8.09), controls 3.97 (5.16)].

Conclusions

The lower‐leg percentage difference in the TKA group is comparable with that of healthy subjects. R0 can be used for oedema evaluation following TKA surgery, as there was no sign of alteration from the metallic implant. These findings indicate the potential for early oedema evaluation after TKA. More research is warranted to extensively validate the application of BIS for oedema evaluation after TKA. Copyright © 2012 John Wiley & Sons, Ltd.
Molecular basis for dramatic changes in cannabinoid CB1 G protein‐coupled receptor activation upon single and double point mutations
Authors: Scott Caitlin E. , Abrol Ravinder , Ahn Kwang H. , Kendall Debra A. , Goddard William A.
Published: November 2012

There is considerable interest in determining the activation mechanism of G protein‐coupled receptors (GPCRs), one of the most important types of proteins for intercellular signaling. Recently, it was demonstrated for the cannabinoid CB1 GPCR, that a single mutation T210A could make CB1 completely inactive whereas T210I makes it essentially constitutively active. To obtain an understanding of this dramatic dependence of activity on mutation, we used first‐principles‐based methods to predict the ensemble of low‐energy seven‐helix conformations for the wild‐type (WT) and mutants (T210A and T210I). We find that the transmembrane (TM) helix packings depend markedly on these mutations, leading for T210A to both TM3+TM6 and TM2+TM6 salt‐bridge couplings in the cytoplasmic face that explains the inactivity of this mutant. In contrast T210I has no such couplings across the receptor explaining the ease in activating this mutant. WT has just the TM3+TM6 coupling, known to be broken upon GPCR activation. To test this hypothesis on activity, we predicted double mutants that would convert the inactive mutant to normal activity and then confirmed this experimentally. This CB1 activation mechanism, or one similar to it, is expected to play a role in other constitutively active GPCRs as well.
Using comparative genomics to uncover new kinds of protein‐based metabolic organelles in bacteria
Authors: Jorda Julien , Lopez David , Wheatley Nicole M. , Yeates Todd O.
Published: November 2012

Bacterial microcompartment (MCP) organelles are cytosolic, polyhedral structures consisting of a thin protein shell and a series of encapsulated, sequentially acting enzymes. To date, different microcompartments carrying out three distinct types of metabolic processes have been characterized experimentally in various bacteria. In the present work, we use comparative genomics to explore the existence of yet uncharacterized microcompartments encapsulating a broader set of metabolic pathways. A clustering approach was used to group together enzymes that show a strong tendency to be encoded in chromosomal proximity to each other while also being near genes for microcompartment shell proteins. The results uncover new types of putative microcompartments, including one that appears to encapsulate B12‐independent, glycyl radical‐based degradation of 1,2‐propanediol, and another potentially involved in amino alcohol metabolism in mycobacteria. Preliminary experiments show that an unusual shell protein encoded within the glycyl radical‐based microcompartment binds an iron‐sulfur cluster, hinting at complex mechanisms in this uncharacterized system. In addition, an examination of the computed microcompartment clusters suggests the existence of specific functional variations within certain types of MCPs, including the alpha carboxysome and the glycyl radical‐based microcompartment. The findings lead to a deeper understanding of bacterial microcompartments and the pathways they sequester.
Broad‐substrate screen as a tool to identify substrates for bacterial Gcn5‐related N‐acetyltransferases with unknown substrate specificity
Authors: Kuhn Misty L. , Majorek Karolina A. , Minor Wladek , Anderson Wayne F.
Published: November 2012

Due to a combination of efforts from individual laboratories and structural genomics centers, there has been a surge in the number of members of the Gcn5‐related acetyltransferasesuperfamily that have been structurally determined within the past decade. Although the number of three‐dimensional structures is increasing steadily, we know little about the individual functions of these enzymes. Part of the difficulty in assigning functions for members of this superfamily is the lack of information regarding how substrates bind to the active site of the protein. The majority of the structures do not show ligand bound in the active site, and since the substrate‐binding domain is not strictly conserved, it is difficult to predict the function based on structure alone. Additionally, the enzymes are capable of acetylating a wide variety of metabolites and many may exhibit promiscuity regarding their ability to acetylate multiple classes of substrates, possibly having multiple functions for the same enzyme. Herein, we present an approach to identify potential substrates for previously uncharacterized members of the Gcn5‐related acetyltransferase superfamily using a variety of metabolites including polyamines, amino acids, antibiotics, peptides, vitamins, catecholamines, and other metabolites. We have identified potential substrates for eight bacterial enzymes of this superfamily. This information will be used to further structurally and functionally characterize them.
Human C3a and C3a desArg anaphylatoxins have conserved structures, in contrast to C5a and C5a desArg
Authors: Bajic Goran , Yatime Laure , Klos Andreas , Andersen Gregers Rom
Published: November 2012

Complement is a part of innate immunity that has a critical role in the protection against microbial infections, bridges the innate with the adaptive immunity and initiates inflammation. Activation of the complement, by specific recognition of molecular patterns presented by an activator, for example, a pathogen cell, in the classical and lectin pathways or spontaneously in the alternative pathway, leads to the opsonization of the activator and the production of pro‐inflammatory molecules such as the C3a anaphylatoxin. The biological function of this anaphylatoxin is regulated by carboxypeptidase B, a plasma protease that cleaves off the C‐terminal arginine yielding C3a desArg, an inactive form. While functional assays demonstrate strikingly different physiological effects between C3a and C3a desArg, no structural information is available on the possible conformational differences between the two proteins. Here, we report a novel and simple expression and purification protocol for recombinant human C3a and C3a desArg anaphylatoxins, as well as their crystal structures at 2.3 and 2.6 Å, respectively. Structural analysis revealed no significant conformational differences between the two anaphylatoxins in contrast to what has been reported for C5a and C5a desArg. We compare the structures of different anaphylatoxins and discuss the relevance of their observed conformations to complement activation and binding of the anaphylatoxins to their cognate receptors.
The effect of top contact on ZnO write‐once–read‐many‐times memory
Authors: Qi Jing , Zhang Qing , Liu Jianlin
Published: November 2012

Write‐once–read‐many‐times memory (WORM) devices were fabricated using Ti/Au and Au as top contacts on ZnO thin films on Si. Electrical characterization shows that both types of WORM devices have large resistance OFF/ON ratio (R ratio), small resistance distribution range, long retention and good endurance. WORM devices with Au top contact have better performance of higher R ratio because of a larger work function of Au compared to Ti.

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(© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)