bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of implementing the washington state ergonomics rule on employer reported risk factors and hazard reduction activity
Authors: Foley Michael , Silverstein Barbara , Polissar Nayak , Neradilek Blazej
Published: October 2008

Background

In Washington State an ergonomics rule was adopted in 2000 that focused on primary prevention. The implementation process followed a 6‐year phase‐in schedule where employers came into compliance based upon their size and industry. In late 2003 the rule was repealed by an industry‐funded voter initiative. Evaluating the implementation of this rule offers a unique opportunity to observe the general deterrent effect of a new public health regulation and to study how employers and workers responded to new requirements.

Methods

Weighted survey regression methods were used to analyze the results from three employer surveys covering more than 5,000 workplaces administered in 2001, 2003, and 2005. These were compared to a baseline employer survey conducted in 1998 before the rule was promulgated. Questions covered the following topics: WMSDs experienced at the workplace; levels of employee exposure to musculoskeletal hazards; steps being taken, if any, to address these hazards; results of these steps; and sources of ergonomic information/assistance used.

Results

From 1998 to 2003 there was a reduction in reported exposures among workplaces in the highest hazard industries. Following the rule's repeal, however, hazard exposures increased. While more workplaces reported taking steps to reduce exposures between 1998 and 2001, this gain was reversed in 2003 and 2005. Employers who took steps reported positive results in injury and absenteeism reduction. Large workplaces in the high hazard industries were more active in taking steps and used a wide variety of resources to address ergonomics issues. Small employers relied more on trade associations and the state. Am. J. Ind. Med. 52:1–16, 2009. © 2008 Wiley‐Liss, Inc.
Effect of protective filters on fire fighter respiratory health: field validation during prescribed burns
Authors: De Vos Annemarie J.B.M. , Cook Angus , Devine Brian , Thompson Philip J. , Weinstein Philip
Published: October 2008

Background

Bushfire smoke contains a range of air toxics. To prevent inhalation of these toxics, fire fighters use respiratory equipment. Yet, little is known about the effectiveness of the equipment on the fire ground. Experimental trials in a smoke chamber demonstrated that, the particulate/organic vapor/formaldehyde (POVF) filter performed best under simulated conditions. This article reports on the field validation trials during prescribed burns in Western Australia.

Methods

Sixty‐seven career fire fighters from the Fire and Emergency Services Authority of Western Australia were allocated one of the three types of filters. Spirometry, oximetry, self‐reported symptom, and personal air sampling data were collected before, during and after exposure to bushfire smoke from prescribed burns.

Results

Declines in FEV1 and SaO2 were demonstrated after 60 and 120 min exposure. A significant higher number of participants in the P filter group reported increases in respiratory symptoms after the exposure. Air sampling inside the respirators demonstrated formaldehyde levels significantly higher in the P filter group compared to the POV and the POVF filter group.

Conclusions

The field validation trials during prescribed burns supported the findings from the controlled exposure trials in the smoke chamber. Testing the effectiveness of three types of different filters under bushfire smoke conditions in the field for up to 2 hr demonstrated that the P filter is ineffective in filtering out respiratory irritants. The performance of the POV and the POVF filter appears to be equally effective after 2 hr bushfire smoke exposure in the field. Am. J. Ind. Med. 52:76–87, 2009. © 2008 Wiley‐Liss, Inc.
Synthesis and characteristics of photoactive‐hydrogenated rosin epoxy methacrylate for pressure sensitive adhesives
Authors: Do Hyun‐Sung , Park Jin‐Hee , Kim Hyun‐Joong
Published: October 2008

Hydrogenated rosin epoxy methacrylate (HREM), based on hydrogenated rosin and glycidyl methacrylate (GMA), was synthesized for use as an advanced tackifier in the UV‐crosslinking pressure sensitive adhesives (PSAs) system. The HREM, as a tackifier, contained UV‐curing sites; thus, allowed photopolymerization to occur by UV irradiation. This UV‐curable tackifier, HREM, can improve the curing rate and adhesion performance of UV‐crosslinking PSAs. The characteristics of HREM were analyzed by GPC and DSC and its synthetic mechanism studied using FTIR and 1H NMR; the characteristic peaks of hydrogenated rosin and GMA vanished, but new peaks for HREM appeared. The PDI and the Tg by DSC were 1 and −25.6°C, respectively. The photopolymerization of HREM was studied using photo‐DSC. Heat flow was observed during UV irradiation, and the curing rate and conversion both increased with rising photoinitiator content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Membrane formation of poly(vinylidene fluoride)/poly(methyl methacrylate)/diluents via thermally induced phase separation
Authors: Ma Wenzhong , Chen Shuangjun , Zhang Jun , Wang Xiaolin , Miao Wenhu
Published: October 2008

The role of the single diluents and mixed diluents on the poly (vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend membranes via thermally induced phase separation (TIPS) process was investigated. The crystallization behaviors of PVDF in the diluted samples were examined by differential scanning calorimetry. The melting and crystallization temperatures of those diluted PVDF blend were decreased with the enhanced interactions between polymer chains and diluent molecules. The crystallinity of PVDF in the diluent was always higher than that obtained in PVDF blend sample. This can be explained by the dilution effects, which increased the average spatial separation distances between crystallizable chains. Thus, the PVDF crystallization was favored. Additionally, solid‐liquid (S‐L) phase separation occurred in the quenched samples. Illustrated by scanning electron microscopy, inter‐ and intraspherulitic voids were formed in the ultimate membranes, which related to the polymer/diluent interactions, the kinetics of crystallization and diluent rejection from the growing crystal. The porosity of the PVDF blend membranes obtained from the mixed diluents was higher than those obtained from the single diluent samples. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Swelling properties of copolymers of styrene and divinylbenzene containing sulfonic and carboxylic acid groups
Authors: Chee Swee Yong , Gan Seng Neon
Published: October 2008

Copolymers of styrene, divinylbenzene, and acrylic acid that have undergone sulfonation exhibited good water absorbency properties. Removal of the lower molecular weight fraction in the surface region of the copolymer particles by toluene extraction before sulfonation has further increased the water swelling capacity of the sulfonated copolymers. The extent of swelling of the UV‐irradiated copolymer could be related to the ratio of divinylbenzene to styrene. The less crosslinked copolymers were shown to absorb more water. The incorporation of more carboxylate groups in the copolymer could further increase its swelling capacity. Without UV irradiation, the carboxylate containing copolymer was found to absorb more water than the sulfonated copolymer. UV irradiation has induced more effective crosslinking in the carboxylate containing copolymer, hence impairing its water absorbency. By replacing styrene and divinylbenzene partially with butyl acrylate, whereby the amount of crosslinking was reduced, the copolymer was able to absorb water 110 times of its dry weight. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Multifractality in the copolymerization of Bis‐GMA/TEGDMA by pulsed photoacoustics
Authors: Navarrete M. , Pineda J. , Vera‐Graziano R.
Published: October 2008

Fractal development during polymerization of a dimethacrylate system (Bis‐GMA/TEGDMA) has been studied through the analysis of time series obtained sequentially by pulsed photoacoustics. The photoacoustic signals as obtained in situ during photopolymerization of Bis‐GMA/TEDGMA were analyzed by rescaled range analysis, dispersion analysis, and detrended fluctuation analysis methods. The analysis reveals the presence of more than one scaling parameter and, therefore, belongs to a complex process known as multifractal. The evolution of fractality during photopolymerization was compared under equivalent conditions with the chemical conversion (of dimethacrylate double bonds) as a function of time, as monitor by infrared spectroscopy. This kinetic study was also used to correlate the fractal nature of the dimethacrylate reaction system with the condensed‐state transitions emerging during the photochemical reaction. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Crystallization behavior of elastomeric block copolymers: Thermoplastic polyurethane and polyether‐block‐amide
Authors: Begenir Asli , Michielsen Stephen , Pourdeyhimi Behnam
Published: October 2008

The isothermal crystallization kinetics of melt‐blown webs produced from a series of elastomeric block copolymers was studied through differential scanning calorimetry (DSC). Three hardness grades were selected for a polyester and a polyether Elastollan® thermoplastic polyurethane and Pebax® polyether‐block‐amide copolymers. The Avrami crystallization kinetics parameters, k and n, were derived from two different methods: (1) traditional Avrami model and (2) derivative of the Avrami model proposed by Kurajica et al. (Croat Chem Acta 2002, 75, 693). The kinetic parameters from both models were consistent and showed good correlation. For all polymer types and hardness grades, crystallization kinetics were interpreted with the derivative model (Kurijica et al.) since it could be directly fitted to untransformed DSC isothermal crystallization data, and thus reduces the errors involved in Avrami analysis. The values of the Avrami exponent, n ranged between 2.59 and 3.41, indicating similar nucleation and growth mechanisms. These n values and morphological observations indicate that crystallization occurs in these copolymers in three dimensions from pre‐existing nuclei and the crystals grow under isothermal conditions. This suggests that, in these elastomeric copolymers, crystallization of the hard segments drives microphase separation into crystalline and amorphous regions rather than formation of hard and soft domains. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Nonisothermal crystallization kinetics of nucleated poly(ethylene terephthalate)
Authors: Deshpande V. D. , Jape Sandeep
Published: October 2008

Studies of the nonisothermal crystallization kinetics of poly(ethylene terephthalate) nucleated with anhydrous sodium acetate were carried out. The chemical nucleating effect was investigated and confirmed with Fourier transform infrared and intrinsic viscosity measurements. The Avrami, Ozawa, and Liu models were used to describe the crystallization process. The rates of crystallization, which initially increased, decreased at higher loadings of the additive. The activation energy, calculated with Kissinger's method, was lower for nucleated samples. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Sulfonated poly(ether ether ketone)/epoxy/phenol novolac blend proton‐exchange membranes with low methanol permeability
Authors: Fu Tiezhu , Zhong Shuangling , Cui Zhiming , Zhao Chengji , Shi Yuhua , Yu Wenzhi , Na Hui , Xing Wei
Published: October 2008

A crosslinked epoxy [4,4′‐diglycidyl‐(3,3′,5,5′‐tetramethylbiphenyl) epoxy resin (TMBP)], cured by phenol novolac (PN), was introduced into a sulfonated poly(ether ether ketone) (SPEEK) membrane (ion‐exchange capacity = 2.0 mequiv/g) with a casting‐solution, evaporation, and heating crosslinking method to improve the mechanical properties, dimensional stability, water retention, and methanol resistance. By Fourier transform infrared analysis, the interactions between the sulfonic acid groups and hydroxyl groups in the blend membranes were confirmed. The microstructure and morphology of the blend membranes were investigated with atomic force microscopy. As expected, the blend membranes showed excellent mechanical properties, good thermal properties (thermal stability above 200°C), lower swelling ratios (1.4% at 25°C and 7.0% at 80°C), higher water retention (water diffusion coefficient = 9.8 × 10−6 cm2/s), and a lower methanol permeability coefficient (3.6 × 10−8 cm2/s) than the pristine SPEEK membrane. Although the proton conductivity of the blend membranes decreased, a higher selectivity (ratio of the proton conductivity to the methanol permeability) was obtained than that of the pristine SPEEK membrane. The results showed that the SPEEK/TMBP/PN blend membranes could have potential use as proton‐exchange membranes in direct methanol fuel cells. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Polyurethane‐solid wood composites prepared with various catalysts. I. Mechanical properties and dimensional stabilities
Authors: Gao Zhenhua , Wu Di , Su Wenqiang , Ding Xiaoling
Published: October 2008

Polyurethane (PU)‐solid wood composites were prepared by impregnating PU prepolymer into low‐density fast‐growing poplar solid wood and controlling the prepolymer cured or foamed within wood voids in the presence of the catalysts triethanolamine (TEA), diethylenetriamine (DETA), triethylenediamine (TEDA), and N‐methyl morpholine (NMM), respectively. A scanning electron microscope (SEM) was used to observe the morphologies of the cured PU resin and the wood voids, and the effects of catalyst species on the mechanical properties and dimensional stabilities of PU‐wood composites were evaluated. The results indicated that the PU prepolymer cured in the presence of various catalysts resulted in different morphologies and distributions within wood voids, and therefore led to various mechanical properties and dimensional stabilities of the PU‐wood composites. Because of the fact that wood cell walls in the surface layer had apparently collapsed in the presence of catalyst DETA and therefore the wood was densified, the PU‐wood composite prepared with DETA had the best mechanical properties and dimensional stabilities. The PU prepolymer was well impregnated and evenly foamed within the wood in the presence of catalyst NMM, giving the PU‐wood composite prepared with NMM much better dimensional stability as the foamed PU blocked the water transfer between the cells. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Porous microspheres, copolymers of bis[4‐(2‐hydroxy‐ 3‐methacryloyloxypropoxy)phenyl]sulfide, and divinylbenzene as stationary phase for HPLC
Authors: Podkościelna Beata , Bartnicki Andrzej , Gawdzik Barbara
Published: October 2008

Synthesis of highly crosslinked methacrylate copolymers of in form of microspheres is presented. They are prepared from tetrafunctional methacrylate derivative of bis(4‐hydroxyphenyl)sulfide, bis[4‐(2‐hydroxy‐3‐methacryloyloxypropoxy)phenyl]sulfide (BES‐DM), and divinylbenzene (DVB). In chemical structure of these copolymers exhibit hydroxyl and ester groups of hydrophilic nature. Additionally, copolymer contains sulfur atoms coming from BES‐DM monomer. Porous structure of the copolymers in the dry and wet state was studied. Microspheres possessing the largest pore volume and specific surface area were subjected to chromatographic investigations. The results show that polar functional groups existing in the chemical structure of the studied microspheres have influence on reversed‐phase HPLC retention mechanism. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Self assembled hydrophobic nanoclusters of poly(methyl methacrylate) embedded into polyvinyl alcohol based hydrophilic matrix: Preparation and water sorption study
Authors: Shukla Sandeep Kumar , Shaikh A. Wasif , Gunari Nikhil , Bajpai A. K. , Kulkarni R. A.
Published: October 2008

Hydrophilic matrices containing nanosized clusters of hydrophilic moieties have demonstrated potential applications in biomedical field. A novel hydrogel containing nanosized domains (20–35 nm) of hydrophobic moieties of poly(methyl methacrylate) (PMMA) was prepared by grafting crosslinked poly(acrylic acid‐co‐methyl methacrylate) chains onto polyvinyl alcohol (PVA) backbone using an efficient redox system. The graft copolymerization process was investigated to observe the influence of gel components on the kinetic parameters of grafting such as rate of grafting (Rg), grafting yield (Gy) and grafting efficiency (Ge). The prepared graft nanohydrogel was evaluated for its water sorption potential under varying chemical composition of the gel and changing pH, temperature, and ionic strength of the swelling bath. The swelling process was also examined mechanistically and diffusion constants (D) of water molecules through the swellable nanohydrogel were also evaluated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A study of the rheological behavior of high‐temperature polymer electrolyte membrane solutions
Authors: Harris Tequila A. L. , Walczyk Daniel
Published: October 2008

The viscosity behavior of various compositions of polymer electrolyte membrane solutions, which are later hydrolyzed into proton conducting membrane film for fuel cells, is characterized. Using the Carreau‐Yasuda model and time–temperature superposition, an empirical model relating the viscosity as a function of temperature and shear strain rate has been developed for several membrane solution compositions. It is observed that the viscosity of the non‐Newtonian membrane has a strong correlation to the membrane's inherent viscosity (a property determined during membrane synthesis). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thermal and mechanical behavior of flexible polyurethane‐molded plastic films and water‐blown foams with epoxidized soybean oil
Authors: Tu Yuan‐Chan , Suppes Galen J. , Hsieh Fu‐Hung
Published: October 2008

Water‐blown flexible polyurethane foams and molded plastic films were made by replacing 0 to 50% of Voranol® 4701 in the B‐side of foam and plastic film formulation by epoxidized soybean oil (ESBO). Physical properties of foams including density, 50% compression force deflection (CFD), 50% constant deflection compression (CDC), and resilience were determined. A dynamic mechanical spectrometer (DMS) and a differential scanning calorimeter (DSC) were used to characterize the hard segment (HS) and soft segment (SS) ratio and thermal properties of plastic. Various functional groups in both flexible polyurethane foam and plastic film were characterized using Fourier transform‐infrared spectroscopy with attenuated total reflectance (FTIR‐ATR). When increasing the ESBO content, both density and 50% CFD of water‐blown polyurethane foams decreased first, then increased. On the other hand, the 50% CDC and resilience of foams showed a sharp increase and decrease, respectively. When increasing the ESBO content, the peak of tan δ in DMS analysis and Δcp in DSC analysis of plastic films both decreased indicating the hard segment increased and the soft segment decreased in plastic film, respectively. The FTIR‐ATR results also show the hydrogen‐bonded urethane group increased in plastic films with increasing ESBO content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Termite digestomes as sources for novel lignocellulases
Authors: Scharf Michael E. , Tartar Aurélien
Published: October 2008

For most animals, lignocellulose is a nutritionally poor food source that is highly resistant to enteric degradation. Termites, however, have the unique ability to digest lignocellulose with high efficiency, often using it as a sole food source. Another interesting aspect of termite biology is their symbiotic associations with prokaryotic and eukaryotic gut symbionts. Termite symbionts contribute to lignocellulose digestion efficiency, but by no means are they responsible for 100% of lignocellulose digestion in the termite gut. The termite digestome can be defined as the pool of genes, both termite and symbiont, that contribute to lignocellulose depolymerization and digestion, as well as simple sugar fermentation, nutrient transport, and nutrient assimilation. A central goal of termite digestomics research is to define/understand the relative contributions of termite and symbiont gene products to collaborative lignocellulose digestion. While efficient microbial cellulases have already been identified and are presently being used in industrial applications, efficient and inexpensive pre‐treatments for lignin and hemicellulose depolymerization are not yet well developed. In this respect, termite digestomics has already offered significant insights, and can continue to identify relevant enzymes, as well as reveal how to optimally combine and utilize these enzymes for maximum synergy. The topics covered in this review are as follows: lignocellulose structure with emphasis on its potential for depolymerization by termite and gut endosymbiont‐derived digestive enzymes; termite biology and ecology from the perspectives of termite nutrition, gut physiology, and lignocellulose digestion; and trends identified through recent termite digestomics research. © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd
Implications of an interpretive understanding of LCA practice
Authors: Rex Emma , Baumann Henrikke
Published: October 2008

Despite the desirability of a life cycle perspective and many attempts to facilitate life cycle assessment (LCA), industry has been relatively slow to adopt LCA. In this research, we thus set out to investigate the underpinnings of LCA practice in industry. A literature review shows that the present understanding is that ‘structural’ conditions such as location and sector determine the use of LCA in industry. However, a field study of two companies in the Swedish forest product industry (thus in the same sector and country) indicates that LCA practice is shaped more by individual preferences and chance events. Our results imply a more interpretive understanding of LCA practice than has been put forward by previous research. The two types of understanding are discussed and their implications for practitioners in industry, organizations promoting the use of LCA and further research are presented. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment.
Global supply chains and social requirements: case studies of labour condition auditing in the People's Republic of China
Authors: Kortelainen Ketty
Published: October 2008

The purpose of this paper is to (1) discuss the usability of labour condition auditing as a tool, (2) identify main differences between quality and environmental auditing and labour condition auditing and (3) define typical improvement areas in a high technology supply chain in the People's Republic of China (hereafter ‘China’). The increased interest in labour conditions of global supply chains has driven companies to integrate corporate social responsibility (CSR) into supply chain management (SCM) practices. Companies face legal requirements as well as voluntary social requirements. This paper focuses on the empirical part of labour condition auditing at selected factories during 2003 and 2004. Findings from these audits include non‐conformances in health and safety, remuneration, working hours and disciplinary practices. Based on the experiences of the case studies, labour condition auditing is seen as a beneficial tool for inducing continuous improvement in supply chain management, but it requires a new set of skills from the auditors. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment.
Antimicrobial activity of endemic Crataegus tanacetifolia (Lam.) Pers and observation of the inhibition effect on bacterial cells
Authors: Benli Mehlika , Yiğit Nazife , Geven Fatmagül , Güney Kerim , Bingöl Ümit
Published: October 2008

Up to now an increasing number of antibiotic‐resistant bacteria have been reported and thus new natural therapeutic agents are needed in order to eradicate these pathogens. Through the discovery of plants such as Crataegus tanacetifolia (Lam.) Pers that have antimicrobial activity, it will be possible to discover new natural drugs serving as chemotherapeutic agents for the treatment of nosocomial pathogens and take these antibiotic‐resistant bacteria under control. The objective of the present study was to determine antimicrobial activity and the activity mechanism of C. tanacetifolia plant extract. The leaves of C. tanacetifolia, which is an endemic plant, were extracted using methanol and tested against 10 bacterial and 4 yeast strains by using a drop method. It was observed that the plant extract had antibacterial effects on Bacillus subtilis, Shigella, Staphylococcus aureus, and Listeria monocytogenes among the microorganisms that were tested. Minimum inhibitory concentration (MIC) results obtained at the end of an incubation of 24 h were found to be ≥6.16 mg ml−1 for B. subtilis, <394 mg ml−1 for Shigella, and ≥3.08 mg ml−1 for L. monocytogenes and S. aureus and minimum bactericidal concentration (MBC) were found as ≥24.63 mg ml−1 for B. subtilis, ≥394 mg ml−1 for Shigella, ≥6.16 mg ml−1 for L. monocytogenes, and ≥98.5 mg ml−1 for S. aureus. According to the MBC results, it was found that the plant extract had bactericidal effects and in order to explain the activity mechanism and cell deformation of bacterial strains treated with plant extract, the scanning electron microscopy (SEM) was used. The results of SEM showed that the treated cells appeared shrunken and there was degradation of the cell walls. This study, in which the antibacterial effect of C. tanacetifolia was demonstrated, will be a base for further investigations on advanced purification and effect mechanism of action of its active compounds. Copyright © 2008 John Wiley & Sons, Ltd.
Calcium‐Induced Membrane Microdomains Trigger Plant Phospholipase D Activity
Authors: Kuppe Konstantin , Kerth Andreas , Blume Alfred , Ulbrich‐Hofmann Renate
Published: October 2008

Plant α‐type phospholipase D proteins are calcium‐dependent, lipolytic enzymes. The morphology of the aggregates of their phospholipid substrate fundamentally defines the interaction between the enzyme and the surface. Here we demonstrate that the Ca2+‐induced generation of membrane microdomains dramatically activates α‐type phospholipase D from white cabbage. 500‐fold stimulation was observed upon incorporation of 10 mol % 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphate (POPA) into 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine (POPC) vesicles in the presence of Ca2+ ions. Enhanced association of PLDα2 with phospholipid surfaces containing anionic components was indicated by lag phase analysis and film balance measurements. Differential scanning calorimetry showed that the POPA‐specific activation correlates with the phase behavior of the POPC/POPA vesicles in the presence of Ca2+ ions. We conclude from the results that the Ca2+‐induced formation of POPA microdomains is the crucial parameter that facilitates the binding of PLD to the phospholipid surface and suggest that this effect serves as a cellular switch for controlling PLD activity.
Melectin: A Novel Antimicrobial Peptide from the Venom of the Cleptoparasitic Bee Melecta albifrons
Authors: Čeřovský Václav , Hovorka Oldřich , Cvačka Josef , Voburka Zdeněk , Bednárová Lucie , Borovičková Lenka , Slaninová Jiřina , Fučík Vladimír
Published: October 2008

A novel antimicrobial peptide designated melectin was isolated from the venom of the cleptoparasitic bee Melecta albifrons. Its primary sequence was established as H‐Gly‐Phe‐Leu‐Ser‐Ile‐Leu‐Lys‐Lys‐Val‐Leu‐Pro‐Lys‐Val‐Met‐Ala‐His‐Met‐Lys‐NH2 by Edman degradation and ESI‐QTOF mass spectrometry. Synthetic melectin exhibited antimicrobial activity against both Gram‐positive and ‐negative bacteria and it degranulated rat peritoneal mast cells, but its hemolytic activity was low. The CD spectra of melectin measured in the presence of trifluoroethanol and sodium dodecyl sulfate showed a high content α‐helices, which indicates that melectin can adopt an amphipathic α‐helical secondary structure in an anisotropic environment such as the bacterial cell membrane. To envisage the role of the proline residue located in the middle of the peptide chain on biological activity and secondary structure, we prepared several melectin analogues in which the Pro11 residue was either replaced by other amino acid residues or was omitted. The results of biological testing suggest that a Pro kink in the α‐helical structure of melectin plays an important role in selectivity for bacterial cells. In addition, a series of N‐ and C‐terminal‐shortened analogues was synthesized to examine which region of the peptide is related to antimicrobial activity.
Nanoparticle‐Based Electrochemical Immunosensor for the Detection of Phosphorylated Acetylcholinesterase: An Exposure Biomarker of Organophosphate Pesticides and Nerve Agents
Authors: Liu Guodong , Wang Jun , Barry Richard , Petersen Catherine , Timchalk Charles , Gassman Paul L , Lin Yuehe
Published: October 2008

A nanoparticle‐based electrochemical immunosensor has been developed for the detection of phosphorylated acetylcholinesterase (AChE), which is a potential biomarker of exposure to organophosphate (OP) pesticides and chemical warfare nerve agents. Zirconia nanoparticles (ZrO2 NPs) were used as selective sorbents to capture the phosphorylated AChE adduct, and quantum dots (ZnS@CdS, QDs) were used as tags to label monoclonal anti‐AChE antibody to quantify the immunorecognition events. The sandwich‐like immunoreactions were performed among the ZrO2 NPs, which were pre‐coated on a screen printed electrode (SPE) by electrodeposition, phosphorylated AChE and QD‐anti‐AChE. The captured QD tags were determined on the SPE by electrochemical stripping analysis of its metallic component (cadmium) after an acid‐dissolution step. Paraoxon was used as the model OP insecticide to prepare the phosphorylated AChE adducts to demonstrate proof of principle for the sensor. The phosphorylated AChE adduct was characterized by Fourier transform infrared spectroscopy (FTIR) and mass spectroscopy. The binding affinity of anti‐AChE to the phosphorylated AChE was validated with an enzyme‐linked immunosorbent assay. The parameters (e.g., amount of ZrO2 NP, QD‐anti‐AChE concentration,) that govern the electrochemical response of immunosensors were optimized. The voltammetric response of the immunosensor is highly linear over the range of 10 pM to 4 nM phosphorylated AChE, and the limit of detection is estimated to be 8.0 pM. The immunosensor also successfully detected phosphorylated AChE in human plasma. This new nanoparticle‐based electrochemical immunosensor provides an opportunity to develop field‐deployable, sensitive, and quantitative biosensors for monitoring exposure to a variety of OP pesticides and nerve agents.
Synthesis of Compounds Presenting Three and Four Anthracene Units as Potential Connectors To Mediate Infinite Lateral Growth at the Air/Water Interface
Authors: Münzenberg Cindy , Rossi Antonella , Feldman Kirill , Fiolka Reto , Stemmer Andreas , Kita‐Tokarczyk Katarzyna , Meier Wolfgang , Sakamoto Junji , Lukin Oleg , Schlüter A. Dieter
Published: October 2008

We report the synthesis of molecular sheets based on the photochemically initiated dimerization of monomers with lateral anthracene units. The film thickness and composition were investigated by ellipsometry and X‐ray photoelectron spectroscopy (XPS). The mechanical stability of the film was sufficient to span it over 45×45 μm‐sized holes. Several model reactions were performed to illustrate the underlying chemistry and to assist in analysis. The reported experiments are considered first steps towards the ultimate goal of the rational synthesis of laterally “infinite”, one‐monomer‐unit‐thick molecular sheets with a long‐range positional order and a periodic covalent‐bonding pattern. Such sheets are referred to as 2D polymers and are considered a prime goal of chemical synthesis with intriguing applications.
Three‐Dimensional Encapsulation of Live Cells by Using a Hybrid Matrix of Nanoparticles in a Supramolecular Hydrogel
Authors: Ikeda Masato , Ueno Shiori , Matsumoto Shinji , Shimizu Yusuke , Komatsu Harunobu , Kusumoto Ken‐ichi , Hamachi Itaru
Published: October 2008

From a library of glyco‐lipid mimics with muconic amide as the spacer, we found that 1, a glyco‐lipid that has N‐acetyl glucosamine and methyl cyclohexyl groups as its hydrophilic head and hydrophobic tails, respectively, formed a stable hydrogel (0.05 wt %) through hierarchical self‐assembly of the lipid molecules into supramolecular nanofibers. The formation of the supramolecular hydrogel was verified by rheological measurements, and the supramolecular nanofiber was characterized as the structural element by transmission electron microscopy and atomic force microscopy observations. Absorption and circular dichroism spectroscopic measurements revealed that the muconic amide moieties of 1 are arranged in a helical, stacked fashion in the self‐assembled nanofibers. Moreover, we unexpectedly found that the homogeneous distribution of the supramolecular nanofibers of 1 was greatly facilitated by the addition of polystyrene nanobeads (100–500 nm in diameter), as evaluated by confocal laser scanning microscopic observations. It is interesting that the obtained supramolecular hybrid matrix can efficiently encapsulate and distribute live Jurkat cells in three dimensions under physiological conditions. This supramolecular hybrid matrix is intriguing as a unique biomaterial.
Coordination Behaviour of Gold and Silver Towards Pyrazole Ligands
Authors: Crespo Olga , Concepción Gimeno M. , Jones Peter G. , Laguna Antonio , Naranjo Mar , Villacampa M. Dolores
Published: October 2008

Treatment of pyrazole ligands HL (HL = pyrazole or 3,5‐dimethylpyrazole) with the gold(I) compound [Au(C6F5)(tht)] (tht = tetrahydrothiophene) gives either the complexes [Au(C6F5)(HL)] or, if the reaction is carried out in a molar ratio of 1:2 and in the presence of a base, the pyrazolate compound [NBu4][{Au(C6F5)}2(μ‐L)]. Binuclear derivatives with bridging pyrazolate ligands have been obtained by treatment of the ligands with [O(AuPPh3)3][ClO4] or [Au2Cl2(μ‐dppf)] (dppf = 1,1′‐bis(diphenylphosphanyl)ferrocene) and Na2CO3, to give [(AuPPh3)2(μ‐L)][ClO4] or [Au2(μ‐L)(μ‐dppf)]Cl. Treatment of [Ag(OTf)(PPh3)] with the pyrazole ligands affords the dimeric species [Ag2(μ‐OTf)2(HL)2(PPh3)2]. Gold(III) derivatives have been accessed by treatment of the pyrazole ligands with [Au(C6F5)3(OEt2)] or [Au(C6F5)2(OEt2)2][ClO4], affording the species [Au(C6F5)3(HL)] or [Au(C6F5)2(HL)2][ClO4]. Gold(III) pyrazolate derivatives of the form trans‐[NBu4][Au(C6F5)2Cl(L)] or [{Au(C6F5)2}2(μ‐L)2] have been prepared from [NBu4][Au(C6F5)2Cl2] or [Au(acac)(C6F5)2]. X‐ray structural characterization has been carried out for eight compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Germylenes and Stannylenes with Chelating Anilido–Imine Ligands: Syntheses, Structures and Reactivity
Authors: Mcheik Ali , Katir Nadia , Castel Annie , Gornitzka Heinz , Massou Stéphane , Rivière Pierre , Hamieh Tayssir
Published: October 2008

Germylenes and stannylenes with anilido–imine ligands were synthesized in high yields by the reaction of group 14 dichlorides (Cl2Ge·dioxane, Cl2Sn) and the lithium salts of the ligands. Complexes were characterized by 1H and 13C NMR spectroscopy, and the molecular structure of methoxygermylene was determined by X‐ray crystallography. These data indicate the formation of N,N′‐chelate complexes having three‐coordinate germanium or tin atoms and quasiplanar six‐membered heterocycles. In the germanium series, cycloaddition reactions with o‐quinone were performed, and the structures of the cycloadducts were determined by X‐ray structure analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Pyrenylamino Acids: Synthesis, Photophysical and Electrochemical Studies
Authors: Abreu Ana S. , Castanheira Elisabete M. S. , Ferreira Paula M. T. , Monteiro Luís S. , Pereira Goreti , Queiroz Maria‐João R. P.
Published: October 2008

Several β‐pyrenyldehydroamino acids and a pyrenylalanine derivative have been synthesized in good‐to‐high yields from dehydroamino acids by several types of reactions. A β‐[(pyren‐1‐yl)methylamino]alanine was prepared by treating the methyl ester of N,N‐(di‐tert‐butoxycarbonyl)dehydroalanine with (pyren‐1‐yl)methylamine hydrochloride in the presence of an excess of potassium carbonate. The E isomer of the methyl esters of N‐(tert‐butoxycarbonyl)‐β‐(1,2,4‐triazol‐1‐yl)dehydroalanine and dehydroaminobutyric acid were treated with (pyren‐1‐yl)methylamine hydrochloride in the presence of triethylamine to give the E isomers of the β‐aminomethylpyrene dehydroalanine and dehydroaminobutyric acid derivatives. β‐(Pyren‐1‐yl)dehydrophenylalanine and dehydroaminobutyric acid derivatives were obtained from the pure stereoisomer of the corresponding β‐bromodehydroamino acids and (pyren‐1‐yl)boronic acid by Suzuki cross‐coupling. This reaction was also applied successfully to β‐bromodehydrodipeptides. The electrochemical behaviour of some of the compounds prepared was studied by cyclic voltammetry. The peak potentials for the oxidation and reduction of pyrenylalanines were similar to those reported for pyrene. However, it was found that when the pyrene ring was conjugated with the dehydroamino acid moiety, the compounds had higher oxidation and reduction peak potentials than pyrene. The fluorescence properties of four of the pyrenylamino acids synthesized were evaluated in cyclohexane and alcohols. The methyl ester of N,N‐bis(tert‐butoxycarbonyl)‐β‐[(pyren‐1‐yl)methylamino]alanine presented high fluorescence quantum yields in cyclohexane and ethanol (ΦF = 0.45 and 0.35, respectively). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of Hybrids of D‐Glucose and D‐Galactose with Pyrrolidine‐Based Iminosugars as Glycosidase Inhibitors
Authors: Doddi Venkata Ramana , Kokatla Hari Prasad , Pal A. P. John , Basak Ranjan K. , Vankar Yashwant D.
Published: October 2008

Sugar–iminosugar hybrid molecules made up of D‐glucose and D‐galactose with pyrrolidine‐based iminosugars, viz. 1,4‐dideoxy‐1,4‐imino‐L‐xylitol and 1,4‐dideoxy‐1,4‐imino‐L‐lyxitol, are synthesized from glycal epoxides and found to be moderate glycosidase inhibitors. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
In Situ Fabrication of Noble Metal Nanoparticles Modified Multiwalled Carbon Nanotubes and Related Electrocatalysis
Authors: Qu Jianying , Chen Hongjun , Dong Shaojun
Published: October 2008

Using multiwalled carbon nanotubes (MWNTs) as templates, noble metal (Au, Ag, Pt or Pd) nanoparticles (NPs) were fabricated in situ by electrochemistry with a diameter of 40–60 nm. Further, catalytic behaviors of these composite materials were investigated. Experiments showed that such carbon nanotubes decorated with Pd NPs modified glassy carbon electrodes exhibited higher electrocatalytic ability to some molecules such as evolution of hydrogen, reduction of oxygen and oxidation of ascorbic acid. Atomic force microscopy, X‐ray photoelectron spectroscopy and cyclic voltammetry were used to characterize the film formation and their properties.
Electrochemical Behavior of Thalidomide at a Glassy Carbon Electrode
Authors: Oliveira S. Carlos B. , Vivan Marilene , Oliveira – Brett Ana Maria
Published: October 2008

Thalidomide is an oral drug marketed in the 1950s as a sedative and an anti‐emetic during pregnancy that was removed from the market when its teratogenic side effects appeared in new born children due to inadequate tests to assess the drug's safety. Recent studies evaluating the use of thalidomide in cancer and HIV diseases have sparked renewed interest. The electrochemical behavior of thalidomide on a glassy carbon electrode has been investigated using cyclic, differential and square‐wave voltammetry in aqueous media at different pHs. The oxidation mechanism of thalidomide is an irreversible, adsorption‐controlled process, pH dependent up to values close to the pKa and occurs in two consecutive charge transfer reactions. A mechanism of oxidation of thalidomide involving one electron and one proton to produce a cation radical, which reacts with water and yields a final hydroxylated product is proposed. The reduction of thalidomide is also a pH dependent, irreversible process and occurs in a single step, with the same number of electrons and protons transferred. The reduction mechanism involves the protonation of the nitrogen that bridges the two cyclic groups, and the product of the protonation reaction causes irreversible dissociation. Both thalidomide and the non electroactive oxidation and reduction products are strongly adsorbed on the glassy carbon electrode surface.
Amperometric Detection of 4‐Chlorophenol on Two Types of Expanded Graphite Based Composite Electrodes
Authors: Pop Aniela , Manea Florica , Radovan Ciprian , Malchev Plamen , Bebeselea Adriana , Proca Cristina , Burtica Georgeta , Picken Stephen , Schoonman Joop
Published: October 2008

The assessment of an expanded graphite‐Ag‐zeolite‐epoxy composite (EG‐Z‐Ag‐Epoxy) electrode for the determination of 4‐chlorophenol (4‐CP) is described and compared to the corresponding expanded graphite‐epoxy composite (EG‐Epoxy) electrode. Cyclic voltammetry was used to characterize the electrochemical behavior and determination of 4‐CP at both electrodes in 0.1 M Na2SO4 and 0.1 M NaOH supporting electrolytes. A substantial enhancement of sensitivity for the determination of 4‐CP at the EG‐Z‐Ag‐Epoxy electrode was reached by applying a chemical preconcentration step prior to voltammetric quantification. Also, under these last conditions the lowest limit of detection of 1 μM illustrates the analytical versatility of this electrode in a concentration range where aquatic 4‐chlorophenol pollution is known to occur.
Separation of multiphosphorylated peptide isomers by CZE
Authors: Muetzelburg Marika V. , Hoffmann Ralf
Published: October 2008

A separation of mono, doubly and triply phosphorylated isomers was developed with CZE with an aqueous electrolyte containing 3.9 mol/L formic acid and 30% v/v trifluoroethanol. Thus a mixture of ten phosphopeptides corresponding to the human tau sequence 226–240 was separated within 70 min. Although peptides with different phosphorylation degrees, i.e. 0–3 phosphate groups, were well separated, some of the phosphopeptide isomers containing one or two phosphate groups were only partially separated. The electrolyte system is compatible with both MALDI‐ and ESI‐MS, allowing a direct coupling, and thus could have some interesting applications in proteomics.
Lauroyl peroxide as thermal initiator of lauryl methacrylate monolithic columns for CEC
Authors: Cantó‐Mirapeix Amparo , Herrero‐Martínez José M. , Mongay‐Fernández Carlos , Simó‐Alfonso Ernesto F.
Published: October 2008

The preparation of lauryl methacrylate (LMA)‐based monolithic columns for CEC using lauroyl peroxide (LPO) as thermal initiator of polymerization has been investigated. The influence of initiator amount and composition of porogenic solvent on the physical and electrochromatographic properties of the resulting LMA‐based monoliths was evaluated. A comparison with LMA‐based columns thermally polymerized with AIBN was performed. At a given porogenic solvent composition, LMA stationary phases initiated with LPO showed higher permeabilities and better efficiency values than those prepared using AIBN as initiator. The optimum polymerization mixture found for LPO initiator provided a minimum plate height of 9.5 μm in a polycyclic aromatic hydrocarbon mixture. The produced monolithic beds also exhibited a good run‐to‐run repeatability and column‐to‐column and mixture‐to‐mixture reproducibility, with RSD values below 5.3% for the retention factors, areas and plate heights.
Downregulation of P2X7receptor expression in rat oligodendrocyte precursor cells after hypoxia ischemia
Authors: Wang Li‐Yan , Cai Wen‐Qin , Chen Peng‐Hui , Deng Qi‐Yue , Zhao Cong‐Min
Published: October 2008

Oligodendrocyte precursor cells (OPCs) are the predominant oligodendrocyte‐lineage stage in the cerebral hemispheres of neonatal rat. Prior studies have shown that OPCs are highly vulnerable to hypoxic‐ischemic injury, yet the mechanisms are not well understood. P2X7receptor (P2X7R) is an ATP‐gated ion channel that has unusual properties and plays very complex roles in a variety of neuropathologic conditions. However, little is known about the involvement of P2X7R in OPCs development and injury. The present study was aimed at examining the presence of P2X7R in OPCs and evaluating the change of the receptor expression after hypoxia ischemia. Using Immunofluorescence, RT‐PCR, and western blot analysis, we demonstrated that OPCs expressed P2X7Rin vitroandin vivo. Activation of P2X7R in OPCs in response to 3′‐O‐(4‐benzoyl) benzoyl‐ATP (BzATP) led to an increased mobilization of intracellular calcium [Ca2+]i, formation of large pores and cell death. These functional responses were sensitive to pretreatment of cells with the P2X7R antagonist, Brilliant Blue G (BBG, 100 nM), which was a selective antagonist for P2X7R in nanomole range. A decrease in P2X7R expression was observed in cultured OPCs after exposure to oxygen‐glucose deprivation (OGD) for 2 hin vitro. Using a neonatal hypoxic‐ischemic injury model in postnatal 3 rats, the similar downregulation was also detected in ischemic cerebral cortex, subcortical white matter and hippocampus compared with sham operation controls. In conclusion, the present data demonstrated that OPCs expressed functional P2X7R. The post‐ischemic downregulation of P2X7R suggested a role for this receptor in the pathophysiology of hypoxic‐ischemic brain injury. © 2008 Wiley‐Liss, Inc.
TNF‐α‐ and TRAIL‐resistant glioma cells undergo autophagy‐dependent cell death induced by activated microglia
Authors: Mora Rodrigo , Abschuetz Anette , Kees Tim , Dokic Ivana , Joschko Natalie , Kleber Susanne , Geibig Renate , Mosconi Eric , Zentgraf Hanswalter , Martin‐Villalba Ana , Régnier‐Vigouroux Anne
Published: October 2008

The role of microglia, the brain resident macrophages, in glioma biology is still ill‐defined. Despite their cytotoxic potential, these cells that significantly infiltrate the tumor mass seem to support tumor growth rather than tumor eradication. A proper activation of microglia anti‐tumor activities within the tumor may provide a valuable additional arm of defense to immunotherapies against brain tumors. We herewith report a detailed characterization of (lipopolysaccharide and interferon‐gamma)‐induced anti‐tumor activities of mouse primary microglia towards two TNF‐alpha and TRAIL resistant glioma cell lines, in cell monolayer or spheroid cultures and in collagen‐embedded tumor explants. Irrespective of the mouse strain, stimulated microglia secreted proteic factors that decreased proliferation and migration of these glioma cells and efficiently killed them. Death occurred specifically in glioma cells as demonstrated by the lack of toxicity of microglia supernatant towards primary cultures of astrocytes or neurons. Cell death was characterized by the early accumulation of acidic vesicles, phosphatidylserine exposure, appearance of double‐membrane cytoplasmic vesicles, extensive zeiosis and a very late loss of DNA in cells that had lost membrane integrity. Inhibition of autophagosome formation efficiently protected glioma cells from death whereas caspase inhibition could only prevent DNA loss but not cytotoxicity. Death however, resulted from a blockade by microglia supernatant of the basal autophagic flux present in the glioma cells. These observations demonstrate that glioma cells resistant to apoptotic death ligands could be successfully and specifically killed through autophagy‐dependent death induced by appropriately activated microglia. © 2008 Wiley‐Liss, Inc.