bluuebunny/crossref_metadata_2025 huggingface dataset:
Patterns of organic contaminants in eggs of an insectivorous, an omnivorous, and a piscivorous bird nesting on the Hudson River, New York, USA
Authors: Custer Christine M. , Custer Thomas W. , Dummer Paul M.
Published: June 2010

Belted kingfisher (Ceryle alcyon), spotted sandpiper (Actitus macularia), and tree swallow (Tachycineta bicolor) eggs were collected in 2004 from the upper Hudson River, New York, USA. This area is one of the most polychlorinated biphenyl (PCB)-contaminated locations in North America. Multivariate analyses indicated among species differences in the concentration and composition of PCB congeners, polychlorinated dibenzo-p-dioxin (PCDD), and dibenzofuran (PCDF, PCDD-F when combined with PCDDs) congeners, and chlorinated pesticides. Total PCB concentrations followed the typical food chain biomagnification paradigm of higher concentrations in piscivorous bird eggs and lower concentrations in eggs of species that feed at lower trophic levels. Concentrations in the insectivorous swallows (geometric mean = 6.8 µg/g wet wt) were approximately half the concentrations present in the piscivorous kingfisher (11.7 µg/g) or omnivorous sandpiper (12.6 µg/g). In contrast, PCB toxic equivalents (TEQs) were higher in swallows (1,790 pg/g wet wt) than in either kingfishers (776 pg/g) or sandpipers (881 pg/g). This difference can be mainly attributed to higher PCB77 concentrations in swallows relative to the other two species. Also contrary to the accepted food-chain paradigm, the sum of PCDD-F concentrations and the sum of their TEQs were higher in swallows than in either sandpipers or kingfishers. Metabolic pathway differences in the respective food chains of the three species probably accounted for the differences observed in PCB TEQ, total PCDD-F, and PCDD-F TEQ concentrations among species. Environ. Toxicol. Chem. 2010;29:2286–2296. © 2010 SETAC
Conditional β-Catenin Loss in Mice Promotes Chemical Hepatocarcinogenesis: Role of Oxidative Stress and Platelet-Derived Growth Factor Receptor α/Phosphoinositide 3-Kinase Signaling†
Authors: Zhang Xu-Feng , Tan Xinping , Zeng Gang , Misse Amalea , Singh Sucha , Kim Youngsoo , Klaunig James E. , Monga Satdarshan P. S.
Published: June 2010

Activation of β-catenin, the central effector of the canonical Wnt pathway and a recognized oncogene, has been implicated in hepatocellular carcinoma. We examined

N

-nitrosodiethylamine (DEN)-induced tumorigenesis in hepatic β-catenin conditional knockout mice (β-cat KO). Male β-cat KO and age- and sex-matched littermate controls were given a single intraperitoneal DEN injection and followed for 6-12 months for hepatic tumors. Hepatic tumors were characterized for histology, proliferation, apoptosis, oxidative stress, and specific proteins by way of western blot, immunohistochemistry, and coprecipitation studies. For

in vivo

tumor intervention studies, specific inhibitors were administered intraperitoneally or through drinking water. Intriguingly, β-cat KO mice showed a paradoxical increase in susceptibility to DEN-induced tumorigenesis. This accelerated tumorigenesis is due to increased injury and inflammation, unrestricted oxidative stress, fibrosis, and compensatory increase in hepatocyte proliferation secondary to platelet-derived growth factor receptor α (PDGFRα)/phosphoinositide 3-kinase (PIK3CA)/Akt activation and c-Myc overexpression.

In vitro

suppression of β-catenin expression in hepatoma cells led to enhanced PDGFRα expression, which was abrogated in the presence of nuclear factor κB (NF-κB) inhibitor. Daily treatment of 6-month-old DEN-exposed β-cat KO with PDGFRα inhibitor dramatically reduced tumor numbers and size. Inclusion of

N

-acetyl-L-cysteine, a known antioxidant and NF-κB inhibitor, in the drinking water led to complete abolition of tumorigenesis in DEN-exposed β-cat KO.

Conclusion:

Loss of β-catenin impairs the liver's ability to counteract DEN-induced oxidative stress and enhances tumorigenesis through PDGFRα/PIK3CA/Akt signaling. Blockade of PDGFRα or oxidative stress dramatically affects β-catenin–deficient tumorigenesis. Also, hepatoma cells use PDGFRα/PIK3CA signaling as an escape mechanism following β-catenin suppression, and their sequential suppression profoundly impedes tumor proliferation.
Immune reconstitution of B‐cell lymphoma patients receiving CHOP‐based chemotherapy containing rituximab
Authors: Kurokawa Toshiro , Hase Makiko , Tokuman Naoko , Yoshida Takashi
Published: June 2010

Sixty‐six B‐cell lymphoma patients were treated with a CHOP‐based chemotherapy containing rituximab (R‐CHOP‐like regimen). Immune reconstitution was assessed by measuring lymphocyte subsets and immunoglobulins. Fifty‐five patients (83.3%) underwent six cycles of the R‐CHOP‐like regimen. CD19+ and CD20+ cells were completely eliminated from the peripheral blood after one cycle of the R‐CHOP‐like regimen; they were detected again 6 months after the therapy. One year after the therapy, B‐cell numbers recovered to their level at diagnosis and almost doubled 2 years after the therapy. The lowest numbers of CD3+, CD8+ and CD56+ cells were seen after three cycles of the regimen, but continued to increase until 1 year after the therapy, remaining stable thereafter. CD4+ T‐cells were at their lowest after six cycles of the regimen and recovered slowly for 2 years after the therapy; however, their numbers were still lower than that at diagnosis. Immunoglobulins decreased over six cycles of the R‐CHOP‐like regimen and then recovered gradually for 2 years after the therapy. The percentage of IgG, IgA and IgM 2 years after the therapy compared with those at diagnosis was 93.9%, 90.1%, 76.3%, respectively. Twelve infectious complications occurred which consisted of three febrile neutropenia, three Herpes Zoster, two tympanitis, two Pneumocystis jiroveci pneumonia and two hepatitis B virus reactivation. B‐cells required 1 year and CD4+ T‐cells and immunoglobulins needed 2 years to recover after the therapy. Copyright © 2010 John Wiley & Sons, Ltd.
Ultrasound‐stimulated peripheral nerve regeneration within asymmetrically porous PLGA/Pluronic F127 nerve guide conduit
Authors: Park Sang Chul , Oh Se Heang , Seo Tae Beom , Namgung Uk , Kim Jin Man , Lee Jin Ho
Published: June 2010

Recently, we developed a novel method to fabricate a nerve guide conduit (NGC) with asymmetrical pore structure and hydrophilicity using poly(lactic‐co‐glycolic acid) (PLGA) and Pluronic F127 by a modified immersion precipitation method. From the animal study using a rat model (sciatic nerve defect of rat), we recognized that the unique PLGA/Pluronic F127 tube provided good environments for nerve regeneration. In this study, we applied low‐intensity pulsed ultrasound as a simple and noninvasive stimulus at the PLGA/F127 NGC‐implanted site transcutaneously in rats to investigate the feasibility of ultrasound for the enhanced nerve regeneration through the tube. The nerve regeneration behaviors within the ultrasound‐stimulated PLGA/Pluronic F127 NGCs were compared with the NGCs without the ultrasound treatment as well as normal nerve by histological and immunohistochemical observations. It was observed that the PLGA/Pluronic F127 tube‐implanted group applied with the ultrasound had more rapid nerve regeneration behavior (∼0.71 mm/day) than the tube‐implanted group without the ultrasound treatment (∼0.48 mm/day). The ultrasound‐treated tube group also showed greater neural tissue area as well as larger axon diameter and thicker myelin sheath than the tube group without the ultrasound treatment, indicating better nerve regeneration. The better nerve regeneration behavior in the our NGC/ultrasound system may be caused by the synergistic effect of the asymmetrically porous PLGA/Pluronic F127 tube with unique properties (selective permeability, hydrophilicity, and structural stability, which can provide good environment for nerve regeneration) and physical stimulus (stimulation of the Schwann cells and activation of the neurotrophic factors). © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.
Study of the production of hydrogen bubbles at low current densities for electroflotation processes
Authors: Jiménez Carlos , Talavera Beatriz , Sáez Cristina , Cañizares Pablo , Rodrigo Manuel A.
Published: June 2010

BACKGROUND: Flotation processes are widely used in waste‐water treatment and it is quite important to have a tool to determine and optimize the size distribution of the bubbles produced. In this work, the electrochemical production of bubbles to enhance the performance of electrocoagulation processes by flotation is studied. To do this, a current density range characteristic of electrocoagulation processes is used to produce microbubbles (<5 mA cm−2), instead of the higher values used in other studies to characterize electroflotation in non‐combined processes.

RESULTS: Current density and pH were found to influence the process significantly. In the range used, higher current densities allow a larger number of small size bubbles to be obtained, appropriate for use in electroflotation processes. However, at the boundaries of the range, the size of the bubbles was increased advising against use. Neutral pH values also favour the formation of small bubbles, and the presence of possible competing reactions have to be considered because they diminish the gas flow and affect the number of bubbles and their size. The roughness of the surface of the electrode material also has an important influence.

CONCLUSIONS: The image acquisition and analysis system developed allows measurement of the size distribution of hydrogen bubbles in the range of current densities studied. Current density and pH seem to be the main parameters affecting the mean diameter of bubbles and the amount of gas produced, and the electrode material may also influence hydrogen production significantly. Copyright © 2010 Society of Chemical Industry
Electrochemical oxidation of Crystal Violet in the presence of hydrogen peroxide
Authors: Zhang Hui , Wu Jie , Wang Zhongqiong , Zhang Daobin
Published: June 2010

BACKGROUND: The combination of electrochemical oxidation using a Ti/RuO2IrO2 anode with hydrogen peroxide has been used for the degradation of Crystal Violet. The effect of major parameters such as initial pH, hydrogen peroxide concentration, current density, electrolyte concentration and hydroxyl radical scavenger on the decolorisation was investigated.

RESULTS: The decolorisation rate increased with initial pH and hydrogen peroxide concentration, but decreased with electrolyte and radical scavenger concentration. The decolorisation rate increased with current density, but the increase became insignificant after current density exceeded 47.6 mA cm−2. On the other hand, hydrogen peroxide decomposition rate increased with initial pH and current density, but decreased with electrolyte and radical scavenger concentration. The amount of hydrogen peroxide decomposed during 30 min reaction increased linearly with hydrogen peroxide dosage. The main intermediates were separated and identified by gas chromatography–mass spectrometry (GC–MS) technique and a plausible degradation pathway of Crystal Violet was proposed. At neutral pH, the electrochemical process in the presence of hydrogen peroxide was more efficient than that in the presence of Fenton's reagent (electro‐Fenton process).

CONCLUSION: The anodic oxidation process could decolorise Crystal Violet effectively when hydrogen peroxide was present. Almost complete decolorisation was achieved after 30 min reaction under the conditions 2.43 mmol L−1 hydrogen peroxide, 47.6 mA cm−2 current density and pH0 7, while 62% COD removal efficiency was obtained when the reaction time was prolonged to 90 min. Copyright © 2010 Society of Chemical Industry
Removal of organic matter in freshwater sediment by microbial fuel cells at various external resistances
Authors: Song Tian‐Shun , Yan Zai‐Sheng , Zhao Zhi‐Wei , Jiang He‐Long
Published: June 2010

BACKGROUND: Besides acting as power sources, sediment microbial fuel cells (SMFC) could be explored to remove organic matter in sediments and then maintain the water quality in aquatic environments. Until now, the role of the external resistance in the removal of organic matter by SMFC has received only limited attention. In this work, the removal of organic matters in sediments by lab‐scale SMFCs at five different external resistances from 10 to 1000 Ω was investigated.

RESLUTS: The external resistance in SMFCs had a strong influence on the working potentials of anodes. Application of a 100 Ω external resistance corresponded to the lowest internal resistance and highest removal efficiency of organic matter in sediment. The removal efficiency of readily oxidizable organic matter in a layer of sediment with a distance of 0–1 cm to the anode reached 28.3 ± 1.9% at 100 Ω external resistance after 2 months of operation. In addition, there existed a linear relationship between current production from the SMFCs and removal efficiency of organic matter from sediments.

CONCLUSIONS: The performance of SMFCs for the removal of organic matter in sediments could be enhanced through the selection of optimal external resistance. The SMFC real‐time removal process could be monitored remotely using current generated. Thus, SMFCs offer an attractive alternative for the environmentally‐friendly removal of organic matter in sediments. Copyright © 2010 Society of Chemical Industry
Preparation and application of a molecularly imprinted polymer for the determination of trace metolcarb in food matrices by high performance liquid chromatography
Authors: Qian Kun , Fang Guozhen , He Jinxing , Pan Mingfei , Wang Shuo
Published: June 2010

In this article, for the first time, a molecularly imprinted polymer (MIP) for the metolcarb was prepared by bulk polymerization using metolcarb as the template, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross‐linker. The prepared polymer was characterized by FT‐IR, static and kinetic adsorption experiments, and the results showed that it has been successfully synthesized and had good selective ability for metolcarb. The MIP was applied as a sorbent in molecularly imprinted SPE coupled with HPLC‐UV for separation and determination of trace metolcarb in three kinds of food matrices at three concentration levels. Under the optimal conditions, the LODs (S/N=3) of cabbage, cucumber and pear were 7.622, 6.455 and 13.52 μg/kg, respectively, and recoveries were in the range of 68.80–101.31% with RSD (n=3) below 3.78% in all cases. To demonstrate further the selectivity of the MIP obtained, a comparison with commercially available C18 SPE was performed. The results indicated that molecularly imprinted SPE showed better chromatography, better selectivity and higher recoveries for metolcarb than commercially available C18 SPE.
Modeling the separation of small peptides by cation‐exchange chromatography
Authors: Harscoat‐Schiavo Christelle , Raminosoa Fenomanana , Ronat‐Heit Evelyne , Vanderesse Régis , Marc Ivan
Published: June 2010

Cation‐exchange chromatography was applied for the separation of short synthetic peptide standards, with various charges and hydrophobicities. The methodology to develop simple, reproducible and accurate models, based on physicochemical peptide properties, was described. A multilinear regression method was used for the calculation of the models, and descriptors were chosen according to the observed phenomena. The predictive and interpretative ability of the chromatographic models was evaluated considering cross‐validated data (root mean‐squared error of calibration, root mean‐squared error, root mean‐squared error of cross‐validation and the Fisher ratio). Hydrophobic coefficients for amino acids were calculated with or without consideration of peptide sequences. A simple model, with only two parameters (charge and hydrophobic coefficient) was built. It enabled an accurate prediction of short peptide elution (up to nine residues). As the model was intended for further characterization of complex mixtures of unknown peptides, some mixtures were analyzed to investigate possible interactions between molecules. Peptides eluted in exactly the same pattern as when injected alone, supporting the use of these models for complex mixtures of small peptides.
A short history of muddy floods
Authors: Boardman J.
Published: June 2010

The term ‘muddy flood’ has been used widely in the lowland, arable areas of western and central Europe to describe muddy runoff from arable fields that causes damage to property. There is some evidence that muddy floods are much more frequent in the last two decades than previously. It is clear though that there is very substantial under‐reporting of the phenomena even in areas where they have been recognised for 20 years e.g. UK and France. Reconstructions based on questionnaires, news media and local authority records have had some success in historical analysis of muddy flood frequency but there is still a huge data deficiency. Records from some countries are woefully lacking e.g. Germany, Spain and Italy.

Costs of muddy flooding are substantial especially in the loess belt of Belgium. The number of properties flooded in France suggests also that costs are high; similarly in England (UK) where costs for case studies are known but not for the country as a whole.

There are two quite different solutions to the problem of muddy flooding. Protection can be provided by engineering devices: retention ponds, dams, trenches. This is an ‘end of pipe’ solution with severe cost implications and risks with regard to the design return period. Alternatively, land use change on relatively small areas of catchments, can be shown to be effective at reducing flood‐risk hazard. A combination of the two has proved most effective at several sites in Europe. Copyright © 2010 John Wiley & Sons, Ltd.
Friction evaluation of lubricated laser‐textured surfaces
Authors: Predescu Adrian , Pascovici Mircea D. , Cicone Traian , Popescu Cristian S. , Grigoriu Constantin , Dragulinescu Dumitru
Published: June 2010

Despite a large amount of work dedicated to the study of the effects of textured surfaces in tribological pairs, there is still a need for accurate and convincing experimental results to prove the benefic effects predicted theoretically. This paper presents an original experimental set‐up with a partially textured flat pin sliding on a rotating disc in the presence of a thin lubricating film of constant thickness. The texture was composed of a series of parallel grooves cut on the half of the pin front face. The main objective of the reported work was the experimental assessment of hydrodynamic performances (load capacity and friction force) for parallel, partially textured sliders and the comparison with a similar step slider. Preliminary results have clearly put in evidence the collective hydrodynamic effect of partially textured surfaces. The stepped configuration has shown greater load capacity with respect to textured configuration. Copyright © 2010 John Wiley & Sons, Ltd.
Interactions of New Synthesized Fluorescent Cationic Amphiphiles Bearing Pyrene Hydrophobe with Plasmid DNA: Binding Affinities, Aggregation and Intracellular Uptake
Authors: Sheng Ruilong , Luo Ting , Zhu Yingdan , Li Hui , Cao Amin
Published: June 2010

In this work, we prepared a novel series of cationic amphiphiles denoted as the Py‐cations (Py‐Gly, Py‐Ala, Py‐Cap, Py‐G1‐Lys and Py‐G2‐Lys) bearing fluorescent pyrene and various hydrocarbon linkers between the pyrene hydrophobe and cationic block. Employing these new cationic amphiphiles with pyrene as the fluorescent probe, the interactions between these Py‐cations and plasmid DNA (pDNA) in distilled water and 0.1 M PBS buffer solution have been explored by means of UV‐vis and fluorescent spectrometers, and ethidium bromide dye displacement and agarose‐gel retardant assays were also implemented to evaluate their pDNA binding affinities in aqueous solution. Furthermore, the average sizes and morphologies of self‐assembled Py‐cation/pDNA lipoplex aggregates were examined by dynamic laser light scattering (DLS) and atomic force microscopy (AFM). It was found that these fluorescent cationic amphiphiles showed blue fluorescence emission of pyrene probe at λ = 340 nm in distilled water while their interactions with pDNA led to new strong green emission at λ = 490 nm, and this may be due to the stacking of pyrene and new formation of excimers via the rigid pDNA templated self‐assembly. It was also revealed that the binding between new Py‐cations and pDNA in aqueous solution was strongly influenced by the Py‐cation hydrophobicity, charges of the cation and the presence of electrolytes. With respect to the Py‐cation/pDNA aggregate morphologies, very interesting 1‐D hybrid nanofibers were predominantly observed by AFM for the Py‐Cap/pDNA aggregates. In addition, utilizing a COS‐7 cell‐line, in‐vitro cellular uptakes of new cationic amphiphiles with pyrene probe were studied and visualized by fluorescent microscopy. As a result, this may provide a new approach to investigate the interactions between synthetic cationic lipids and nucleic acids, and pave an alternative clue to design new organic gene delivery carriers.

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The Design of Polymer‐based Nanocarriers for Effective Transdermal Delivery
Authors: Kim Junoh , Shim Jongwon , Kim Yong‐Jin , Char Kookheon , Suh Kyung‐Do , Kim Jin‐Woong
Published: June 2010

This study reports a facile and practical means to non‐invasively deliver biologically active ingredients through the skin using polymer‐based nanocarriers. For this, polymer nanocapsules were fabricated with different surface charges as well as glass transition temperatures and we observed their ability to deliver the encapsulated active ingredient, coenzyme Q10, through the skin layer. Direct imaging of a probe molecule, Nile Red, and a matrix polymer labeled with fluorescence moiety, Lucifer Yellow, allowed us to demonstrate that the probe molecule readily permeates into the deep skin, while the matrix polymer stays in the stratum corneum layer due to electrostatic interactions. Quantitative characterization of the penetrating amount of coenzyme Q10 using the Frantz cell method proved that, to achieve improved delivery efficiency, the nanocapsule should have a low glass transition temperature as well as positive surface charges.

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Structural investigation on phenyl‐ and pyridin‐2‐ylamino(methylene)naphthalen‐2(3H)‐one. Substituent effects on the NMR chemical shifts
Authors: Venkatachalam Taracad K. , Pierens Gregory K. , Campitelli Marc R. , Reutens David C.
Published: June 2010

Schiff bases bearing phenyl and pyridyl groups were synthesized by condensation of appropriate amines with 2‐hydroxynaphthaldehyde. These Schiff bases were obtained as colored crystalline solids. The proton NMR spectra of these compounds showed a doublet for the NH protons indicating a keto tautomer for these Schiff bases. The pyridyl‐substituted Schiff bases containing hydroxyl moiety were found to show the most downfield shift for the NH protons in DMSO solvent, and this was rationalized due to the formation of a six‐ and five‐membered ring using hydrogen bonds for these two compounds. Correspondingly, the olefinic proton of the Schiff bases is also found to be a doublet due to coupling to the amine proton. These Schiff bases exhibited thermochromic properties. Detailed NMR spectral analysis for both the phenyl‐ and pyridyl‐substituted Schiff bases is presented. Copyright © 2010 John Wiley & Sons, Ltd.
Multi‐time‐step domain coupling method with energy control
Authors: Mahjoubi N. , Krenk S.
Published: June 2010

A multi‐time‐step integration method is proposed for solving structural dynamics problems on multiple domains. The method generalizes earlier state‐space integration algorithms by introducing displacement constraints via Lagrange multipliers, representing the time‐integrated constraint forces over the individual time step. It is demonstrated that displacement continuity between the subdomains leads to cancelation of the interface contributions to the energy balance equation, and thus stability and algorithmic damping properties of the original algorithms are retained. The various subdomains can be integrated in time using different time steps and/or different state‐space time integration schemes. The solution of the constrained system equations is obtained using a dual Schur formulation, allowing for maximum independence of the calculation of the subdomains. Stability and accuracy are illustrated by a numerical example using a refined mesh around concentrated forces. Copyright © 2010 John Wiley & Sons, Ltd.
Don't throw out the baby with the bathwater: Estimating fertility from subadult skeletons
Authors: Robbins Gwen
Published: June 2010

Recent research interest has focused on the bioarchaeology of children. Although paleodemography is essential for accurate reconstructions of lifestyle and health in past populations, currently there is no published technique for estimating fertility and life expectancy at birth for skeletal populations in which adults are under‐enumerated. This paper provides a formula to predict Gross Reproductive Rate (GRR) from the proportion of young infants to subadults in a skeletal population. The formula was developed from 98 of Coale and Demeny's Female Model West Life Tables, which represented diverse fertility and mortality rates. The formula's accuracy was examined using independent samples from historical and archaeological cemeteries. Estimates of GRR from the subadult fertility formula were compared with estimates from Bocquet‐Appel and Masset's juvenile:adult ratio. Results indicate that the subadult fertility formula predicts GRR with consistent accuracy (R2 = 0.98) and precision (± 1 offspring) in the model life tables, across diverse subadult age structures and demographic characteristics. The formula is useful for subadult populations with a proportion of perinates:subadults between 0.12 and 0.45. The adult component of the sample is not included in the analysis and thus the formula is similarly useful in cases where adults are under‐enumerated, or not. When applied to historical and archaeological populations, estimates for GRR are similar to previous estimates from the juvenile:adult ratio. Because crude birth rate and life expectancy at birth can be calculated from GRR using established fertility centred approaches to demography, the subadult fertility formula allows skeletal populations of diverse composition to be included in demographic research, essential for understanding of how mortality and fertility are affecting the morbidity profiles of subadult samples and for comparative bioarchaeological analyses. Copyright © 2010 John Wiley & Sons, Ltd.
Zwitterionic sulfobetaine‐modified non‐woven fabric for blood filtration
Authors: Yang Chao , Sun Kang , Liu Jiaxin , Wang Hong , Cao Ye
Published: June 2010

Blood filtration requires a high removal ratio of leukocytes and with simultaneous high recovery ratio of platelets and other beneficial components. Problems are often encountered with blood filter materials in terms of high platelet loss. Zwitterions such as phosphorylcholine, sulfobetaine and carboxybetaine show effective resistance against protein adsorption and platelet adhesion. The study reported was aimed at achieving surface modification of poly(butylene terephthalate) non‐woven fabric (PBTNF) using UV radiation‐induced graft copolymerization of a zwitterionic sulfobetaine,N‐(3‐sulfopropyl)‐N‐methacroyloxyethyl‐N,N‐dimethylammonium betaine (SMDB), in order to improve the wettability and platelet recovery ratio of the PBTNF. Attenuated total reflection Fourier transform infrared and X‐ray photoelectron spectroscopy results showed that SMDB was successfully grafted onto the PBTNF. Photoinitiator concentration, monomer concentration and UV irradiation time affected markedly the degree of grafting. Critical wetting surface tension, water wetting time and hemolysis tests showed an improvement in wettability and blood compatibility as a result of graft copolymerization of SMDB. A blood filter material composed of SMDB‐modified PBTNF reduced platelet adhesion and had higher platelet recovery compared to poly(acrylic acid)‐modified PBTNF. It was found that SMDB monomer was successfully grafted onto PBTNF using UV radiation. The degree of grafting of SMDB could be controlled by varying the photoinitiator concentration, monomer concentration and UV irradiation time. SMDB‐modified PBTNF showed significant improvement in wettability and blood compatibility. The zwitterionic structure of SMDB is resistant to platelet adhesion. The SMDB‐modified PBTNF could be a candidate for a blood filter material and in other medical applications. Copyright © 2010 Society of Chemical Industry
Biodegradable poly(ester‐ether)s: ring‐opening polymerization of D,L‐3‐methyl‐1,4‐dioxan‐2‐one using various initiator systems
Authors: Lochee Yemanlall , Jhurry Dhanjay , Bhaw‐Luximon Archana , Kalangos Afksendiyos
Published: June 2010

The synthesis and detailed characterization of racemic 3‐methyl‐1,4‐dioxan‐2‐one (3‐MeDX) are reported. The bulk ring‐opening polymerization of 3‐MeDX, to yield a poly(ester‐ether) meant for biomedical applications, in the presence of various initiators such as tin(II) octanoate, tin(II) octanoate/n‐butyl alcohol, aluminium tris‐isopropoxide and an aluminium Schiff base complex (HAPENAlOiPr) under varying experimental conditions is here detailed for the first time. Polymerization kinetics were investigated and compared with those of 1,4‐dioxan‐2‐one. The studies reveal that the rate of polymerization of 3‐MeDX is less than that of 1,4‐dioxan‐2‐one. Experimental conditions to achieve relatively high molar masses have been established. Thermodynamic parameters such as enthalpy and entropy of 3‐MeDX polymerization as well as ceiling temperature have been determined. Poly(D,L‐3‐MeDX) is found to possess a much lower ceiling temperature than poly(1,4‐dioxan‐2‐one). Poly(D,L‐3‐MeDX) was characterized using NMR spectroscopy, matrix‐assisted laser desorption ionization mass spectrometry, size exclusion chromatography and differential scanning calorimetry. This polymer is an amorphous material with a glass transition temperature of about −20 °C. Copyright © 2010 Society of Chemical Industry
Nitrosation of dialkylhydroxylamines, and computational and NMR investigations of the interconversion of conformational isomers of N‐nitroso‐dimethylhydroxylamine
Authors: Crugeiras Juan , Maskill Howard , MacFarlane William , Menneer Iain D. , Rios Ana , Rios Miguel A.
Published: June 2010

The effect of acidity upon the rate of nitrosation of N‐benzyl,O‐methylhydroxylamine (3) in 1:1 (v/v) H2O/MeOH at 25 °C has been investigated. The pseudo‐first‐order rate constant (kobs) for loss of HNO2 as the limiting reagent decreases as [H3O+] increases. This is compatible with two parallel reaction channels (Scheme 2). One involves the direct reaction of the free hydroxylamine with HNO2 (k1 = 1.4 × 102 dm3 mol−1 s−1, 25 °C) and the other involves the reaction of the free hydroxylamine with NO+ (k2 = 5.9 × 109 dm3 mol−1 s−1). In contrast, there is only a very slight increase in kobs with increasing [H3O+] for nitrosation of N,O‐dimethylhydroxylamine (4) in dilute aqueous solution at 25 °C to give N‐nitroso‐dimethylhydroxylamine, 5. This also fits a two‐channel mechanism (Scheme 3). Again, one involves the nitrosation of the free base by NO+ (k2 = 8 × 109 dm3 mol−1 s−1, 25 °C) but the other channel now involves catalysis by chloride (k3 = 1.3 × 108 dm3 mol−1 s−1). Arising from these results, we propose an estimate of pKa ∼ −5 for protonated nitrous acid, (O = NOH), which is appreciably different from the literature value of +1.7.

The interconversion of cis and trans conformational isomers of 5 has been investigated by temperature‐dependent NMR spectroscopy in CDCl3, methanol‐d4, toluene‐d8 and dimethyl sulfoxide‐d6. Enthalpies and entropies of reaction and of activation have been determined and compared with computational values obtained at the B3LYP/6‐31G* level of theory. The cis form is slightly more stable at normal temperatures and no solvent effects upon the thermodynamics or kinetics of the conformational equilibrium were predicted computationally or detected experimentally. In addition, key geometric parameters and dipole moments have been calculated for the cis and trans forms, and for the lowest energy transition structure for their interconversion, in the gas phase and in chloroform. These results indicate electronic delocalisation in the ground states of 5 which is lost in the transition structure for their interconversion. Copyright © 2010 John Wiley & Sons, Ltd.
The role of Buergi‐Dunitz interactions in the structural stability of proteins
Authors: Fufezan Christian
Published: June 2010

Nonbonding interactions are essential for protein stability and maintenance of secondary structure. Their strength, however, is not always experimentally accessible. One example is the stability of collagen, which is in part due to Buergi‐Duntiz or n → π* interactions between the peptide backbone atoms [DeRider et al., J Am Chem Soc 2002;124:2497–2505]. Here, the overall frequency of n → π* interactions in proteins has been investigated. The analysis of a nonredundant set of protein structures showed that 45.1% of all residues have a backbone conformation favoring a n → π* nucleophilic attack between the carbonyl oxygen of residue i − 1 and the carbonyl carbon of residue i. These residues form a substantial fraction of right‐ and left‐handed α helices, 310 helices, π helices, and hydrogen bonded turns. Simulations showed that there are only four regions in Ramachandran space that favor backbone ni−1 → π interactions and these Φ, Ψ combinations are observed with high frequencies in the nonredundant protein structure set. Analysis of carbonyl carbon displacements out of the peptide plane in ultra‐high resolution protein structures indeed reveals the presence of the Buergi‐Dunitz trajectory. The Buergi‐Dunitz interaction thus appears to play an important and general role in protein structure stability that has not hitherto been fully explored. Proteins 2010. © 2010 Wiley‐Liss, Inc.
Dry molten globule intermediates and the mechanism of protein unfolding
Authors: Baldwin Robert L. , Frieden Carl , Rose George D.
Published: June 2010

New experimental results show that either gain or loss of close packing can be observed as a discrete step in protein folding or unfolding reactions. This finding poses a significant challenge to the conventional two‐state model of protein folding. Results of interest involve dry molten globule (DMG) intermediates, an expanded form of the protein that lacks appreciable solvent. When an unfolding protein expands to the DMG state, side chains unlock and gain conformational entropy, while liquid‐like van der Waals interactions persist. Four unrelated proteins are now known to form DMGs as the first step of unfolding, suggesting that such an intermediate may well be commonplace in both folding and unfolding. Data from the literature show that peptide amide protons are protected in the DMG, indicating that backbone structure is intact despite loss of side‐chain close packing. Other complementary evidence shows that secondary structure formation provides a major source of compaction during folding. In our model, the major free‐energy barrier separating unfolded from native states usually occurs during the transition between the unfolded state and the DMG. The absence of close packing at this barrier provides an explanation for why ϕ‐values, derived from a Brønsted‐Leffler plot, depend primarily on structure at the mutational site and not on specific side‐chain interactions. The conventional two‐state folding model breaks down when there are DMG intermediates, a realization that has major implications for future experimental work on the mechanism of protein folding. Proteins 2010. © 2010 Wiley‐Liss, Inc.
Binding of nonsteroidal anti‐inflammatory drugs to Aβ fibril
Authors: Takeda Takako , Chang Wenling E. , Raman E. Prabhu , Klimov Dmitri K.
Published: June 2010

Nonsteroidal anti‐inflammatory drugs are considered as potential therapeutic agents against Alzheimer's disease. Using replica exchange molecular dynamics and atomistic implicit solvent model, we studied the mechanisms of binding of naproxen and ibuprofen to the Aβ fibril derived from solid‐state NMR measurements. The binding temperature of naproxen is found to be almost 40 K higher than of ibuprofen implicating higher binding affinity of naproxen. The key factor, which enhances naproxen binding, is strong interactions between ligands bound to the surface of the fibril. The naphthalene ring in naproxen appears to provide a dominant contribution to ligand‐ligand interactions. In contrast, ligand‐fibril interactions cannot explain differences in the binding affinities of naproxen and ibuprofen. The concave fibril edge with the groove is identified as the primary binding location for both ligands. We show that confinement of the ligands to the groove facilitates ligand‐ligand interactions that lowers the energy of the ligands bound to the concave edge compared with those bound to the convex edge. Our simulations appear to provide microscopic rationale for the differing binding affinities of naproxen and ibuprofen observed experimentally. Proteins 2010. © 2010 Wiley‐Liss, Inc.
AlGaN/GaN/AlGaN double heterojunction HEMTs on n‐type SiC substrates
Authors: Bahat‐Treidel Eldad , Hilt Oliver , Brunner Frank , Würfl Joachim , Tränkle Günther
Published: June 2010

In this paper, we present a systematic study of AlGaN/GaN/AlGaN double heterojunction high‐electron‐mobility‐transistor devices on n‐type SiC substrate and the dependence of the GaN channel layer thickness. A device breakdown voltage enhancement was achieved by increasing the electron confinement in the transistor channel using an AlGaN back barrier‐layer structure. An optimized electron confinement results in a scaling of breakdown voltage with device geometry, low on‐state resistance and a significantly reduced sub‐threshold drain leakage current. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Static skin effect in the quantum Hall regime for high‐mobility electrons on a cylindrical surface
Authors: Friedland K.‐J. , Hey R. , Riedel A. , Maude D. K.
Published: June 2010

We investigate the quantum Hall effect in a highmobility, two‐dimensional electron gas on a cylindrical surface. Due to the varying filling factor along the current path, the electron transport is characterized by sequential transmission along incompressible stripes and compressible bulk regions. For the compressible regions, we observe an exponential decay of the longitudinal resistances by rotating the sample around the cylinder axis. We adopt the model of the so‐called static skin effect for the conductance in the compressible bulk regions and demonstrate that this behavior can be ascribed to probing the skin channel width by moving the Hall bar terminals along the gradient of the magnetic field along the cylinder periphery. We determine L as the characteristic length for the exponential decay of the skin channel width by moving away from the position where the magnetic field is perpendicular to the surface. The values of L are in the sub‐micrometer range, similarly as for low magnetic fields. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Developing winter flow rating relationships using slope‐area hydraulics
Authors: Beltaos Spyros
Published: June 2010

Despite recent advances in instrumentation and modelling methods, accurate determination of river discharge under an ice cover still requires direct measurement. Published flows at hydrometric gauging stations are based on interpolation between a few measurements that are carried out during each winter. The feasibility of using slope‐area hydraulics to develop discharge‐stage rating relationships is explored at two stations, Peace River at Peace Point and Mackenzie River at Arctic Red River. Records at both gauges contain key information for understanding local ice jamming processes, which are known to control the long‐term maintenance of the aquatic ecosystems in the respective deltas. For each site, the variations of reach‐average hydraulic parameters with stage are first determined from several nearby cross‐sections. This information is then used to calculate hydraulic resistance characteristics during the ice season based on archived discharge measurement data, which also include ice cover thickness. The Peace River flow measurements indicate a well‐defined seasonal variation in hydraulic resistance, with the exception of years with large slush deposits under the solid‐ice sheet. Slush effects are negligible at the Mackenzie River gauge site, but the stage‐flow relationship is complicated by a variable water surface slope, a result of downstream control by the Beaufort Sea. This feature is most pronounced during the pre‐breakup period when flows are rising sharply and renders flow estimation uncertain. A nearby water‐level gauge would help quantify the slope and increase confidence in winter flow estimates. Copyright © 2010 in the right of Canada.
The effects of network's structural holes: polycentric institutions, product portfolio, and new venture growth in China and Russia
Authors: Batjargal Bat
Published: June 2010

This study examines the effect of network's structural holes (i.e., the absence of a link between two contacts who are both linked to an actor) on product development and profit growth of software ventures in two different institutional contexts—China and Russia. Using interview data of 159 software entrepreneurs in Beijing and Moscow, the study found that the effect of structural holes is contingent upon country institutional context and venture development stage. Specifically, structural holes have a positive main effect on product portfolio, but a negative main effect on profit growth in the second revenue year (early stage of venture development). Structural holes are more useful in the Russian institutional context compared to the Chinese institutional context due to the polycentricity of institutions. The research implications of the findings are discussed. Copyright © 2010 Strategic Management Society.
Laparoscopic hepatic left lateral sectionectomy using the LaparoEndoscopic Single Site approach: evolution of minimally invasive liver surgery
Authors: Aldrighetti Luca , Guzzetti Eleonora , Ferla Gianfranco
Published: June 2010

Background/purpose

Laparoscopic liver surgery is attracting wider interest for the treatment of benign and malignant neoplasms. Laparoscopy is a safe and feasible approach for lesions located in the left liver lobe. As the emphasis on minimizing the technique continues, single‐port access surgery is quickly evolving. We present our initial experience of single‐port laparoscopic liver surgery using a LaparoEndoscopic Single Site (LESS) approach with the TriPort System (ASC; Advanced Surgical Concepts, Bray, Ireland) to perform a left lateral sectionectomy via a single supraumbilical incision.

Methods

The abdomen was approached through a 15 mm supraumbilical incision and a single‐port access device was used to perform a left lateral sectionectomy in a patient with a single colorectal metastasis.

Results

The total operative time was 145 min, with 50 ml blood loss. Hospital stay was 4 days.

Conclusions

Single‐port laparoscopic left lateral sectionectomy is a feasible procedure, when performed by experienced laparoscopic surgeons. It has to be determined whether or not this approach would offer benefit to patients, except in terms of cosmesis, compared to standard laparoscopic liver resection.
Petrogenetic and tectonic inferences from the study of the Mt Cer pluton (West Serbia)
Authors: KORONEOS A. , POLI G. , CVETKOVIĆ V. , CHRISTOFIDES G. , KRSTIĆ D. , PÉCSKAY Z.
Published: June 2010

The Mt Cer Pluton, Serbia, is a complex laccolith-like intrusion (~ 60 km2), situated along the junction between the southern Pannonian Basin and northern Dinarides. It intrudes Palaeozoic metamorphic rocks causing weak to strong thermal effects. Based on modal and chemical compositions, four rock-types can be distinguished: (1) metaluminous I-type quartz monzonite/quartz monzodiorite (QMZD); (2) peraluminous S-type two-mica granite (TMG), which intrudes QMZD; (3) Stražanica granodiorite/quartz monzonite (GDS); and (4) isolated mafic enclaves (ME), found only in QMZD.40K–39Ar dating and geological constraints indicate that the main quartz monzonite/quartz monzodiorite body of Mt Cer was emplaced not later than 21 Ma, whereas the emplacement ages of the Stražanica granodiorite/quartz monzonite and two-mica granites are estimated at around 18 and 16 Ma, respectively. The Mt Cer pluton is similar to the Mt Bukulja pluton, some 80 km southwestwards. Genesis of QMZD cannot be interpreted by fractional crystallization coupled with mixing or assimilation. It is best explained by a convection–diffusion process between mantle-derived minette/leucominette magmas and GDS-like magmas followed by two end-member magma mixing. The composition of GDS rocks suggests that GDS-like magmas could have formed by melting of lower crustal lithologies similar to amphibolite/metabasalts. The geochemistry of TMG is reproduced by an Assimilation/Fractional Crystallization model with a ratio of rate of assimilation to rate of fractional crystallization of 0.4, using the compositions of the least evolved TMG of the Bukulja pluton and adjacent metamorphic rocks as proxies for the parental magma and contaminant, respectively. The origin and evolution of the Mt Cer and adjacent Mt Bukulja plutons provide new constraints on the Tertiary geodynamics of the northern Dinarides–southern Pannonian region. The quartz monzonite/quartz monzodiorite is interpreted as a result of the Oligocene post-collisional Dinaride orogen-collapse, which included a limited lithosphere delamination, small-scale mantle upwelling, and melting of the lower crust. By contrast, the two-mica granite magmas formed through melting in shallower crustal levels during the extensional collapse in the Pannonian area.
Mitochondrial neurogastrointestinal encephalomyopathy associated with progressive hearing loss
Authors: Hiraki N , Udaka T , Yamamoto H , Kadokawa Y , Ohkubo J , Suzuki H
Published: June 2010

Objective:

We report a rare case of mitochondrial neurogastrointestinal encephalomyopathy with hearing loss.

Case report:

A 46-year-old woman presented with a three-year history of progressive, bilateral hearing loss and tinnitus. She had been suffering from unexplained abdominal pain and diarrhoea for 20 years. When first seen, her otoscopic findings were normal, and pure tone audiometry showed mild and moderate hearing loss in her right and left ears, respectively. She also had: bilateral ophthalmoparesis, neck and limb muscle weakness, and hypoactive deep tendon reflexes on neurological examination; diffuse leukoencephalopathy on magnetic resonance imaging of the brain; and markedly reduced leukocyte thymidine phosphorylase activity. On the basis of these findings, the patient was diagnosed with mitochondrial neurogastrointestinal encephalomyopathy.

Conclusion:

Mitochondrial neurogastrointestinal encephalomyopathy is an autosomal recessive disease caused by mutation of the thymidine phosphorylase gene, and is characterised by ophthalmoparesis, peripheral neuropathy, leukoencephalopathy, gastrointestinal symptoms and abnormal mitochondria in muscle cells. Current advances in genetic research may reveal a higher prevalence of mitochondrial disorders than had previously been thought. Otolaryngologists should be aware of mitochondrial neurogastrointestinal encephalomyopathy and other rare genetic disorders when managing patients with progressive hearing loss.
The WEIRD are even weirder than you think: Diversifying contexts is as important as diversifying samples
Authors: Ceci Stephen J. , Kahan Dan M. , Braman Donald
Published: June 2010

We argue that Henrich et al. do not go far enough in their critique: Sample diversification, while important, will not lead to the detection of generalizable principles. For that it will be necessary to broaden the range of contexts in which data are gathered. We demonstrate the power of contexts to alter results even in the presence of sample diversification.