bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement and numerical prediction of fiber‐reinforced thermoplastics' thermal conductivity in injection molded parts
Authors: Feliciani Claudio , Takai Yoshihiro 
Published: August 2013

ABSTRACTRecent improvements in injection molding numerical simulation software have led to the possibility of computing fiber orientation in fiber reinforced materials during and at the end of the injection molding process. However, mechanical, thermal, and electrical properties of fiber reinforced materials are still largely measured experimentally. While theoretical models that consider fiber orientation for the prediction of those properties exist, estimating them numerically has not yet been practical. In the present study, two different models are used to estimate the thermal conductivity of fiber reinforced thermoplastics (FRT) using fiber orientation obtained by injection molding numerical simulation software. Experimental data were obtained by measuring fiber orientation in injection molded samples' micrographs by image processing methods. The results were then compared with the numerically obtained prediction and good agreement between numerical and experimental fiber orientation was found. Thermal conductivity for the same samples was computed by applying two different FRT thermal conductivity models using numerically obtained fiber orientation. In the case of thermal conductivity, predicted results were consistent with experimental data measurements, showing the validity of the models. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39811.
Mechanical properties of recycled kenaf/polyethylene terephthalate (PET) fiber reinforced polyoxymethylene (POM) hybrid composite
Authors: Dan‐mallam Yakubu , Abdullah Mohamad Zaki , Yusoff Puteri Sri Melor Megat 
Published: August 2013

ABSTRACTEnvironmental concerns have attracted researchers to study the recycling of composite materials and thermoplastics due to the desire not to waste materials and reduce disposal of scraps that may eventually pollute the environment. The main objective of this article is to study the effect of recycling on the mechanical properties of kenaf fiber/PET reinforced POM hybrid composite. The virgin hybrid composite was produced by compression molding and later subjected to mechanical testing. The scraps obtained after the mechanical testing were shredded, granulated and subjected to compression molding to produce samples for mechanical testing. Tensile strength of 27 MPa was obtained and (after second recycling process) which is lower compared to 73.8 MPa obtained for the virgin hybrid composite. There was a significant increase in flexural modulus (4.7 GPa) compared to the virgin hybrid composite. The impact strength dropped to 4.3 J cm−1 as against 10.5 J cm−1 for the virgin hybrid composite. The results of thermal degradation showed about 80% weight loss for kenaf fiber between 300 and 350°C. The weight loss may be due to the degradation of cellulose and hemicellulose content of the fiber. The percentage water absorption of the recycled composite dropped by about 80% compared to the virgin hybrid composite. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39831.
ALLOCATION OF CYSTEINE FOR GLUTATHIONE PRODUCTION IN CATERPILLARS WITH DIFFERENT ANTIOXIDANT DEFENSE STRATEGIES: A COMPARISON OF Lymantria dispar AND Malacosoma disstria
Authors: Barbehenn Raymond V. , Kochmanski Joseph , Menachem Brandon , Poirier Lisa M. 
Published: August 2013

Sulfur amino acids [cysteine (Cys) and methionine (Met)] play two major roles during animal development: protein synthesis for growth and glutathione synthesis for defense. For caterpillars, the levels of sulfur amino acids found in foliar protein can be especially low relative to their nutritional needs. Previous work has measured concentrations of glutathione (GSH; containing Cys) in specific animal tissues, but has not examined whole‐body levels to ascertain the costliness of this defense in terms of Cys allocation. This study examined whether the production of GSH varies between species and within individuals in accordance with an insect's need for antioxidant defense. Secondly, we quantified the allocation of total Cys (peptide‐bound plus free Cys) to GSH in caterpillars as an estimate of its cost. Two contrasting species were compared: Lymantria dispar (Lymantriidae), a species that is highly defended, and Malacosoma disstria (Lasiocampidae), a species that is less defended. As expected, GSH levels were significantly higher in L. dispar than in M. disstria. Consistent with the function of the midgut as a first line of defense against ingested toxins, GSH levels were significantly higher in these tissues than in the whole bodies of both species. A major finding in this study was that a large fraction of total Cys is used to produce GSH: GSH in the midguts of L. dispar and M. disstria contained 23 and 21%, respectively, of the total Cys in these tissues, and the GSH in their remaining body tissues contained 19 and 17% of the total Cys in these tissues. Levels of total Cys in caterpillar tissues followed the same pattern of distribution as did GSH, producing a strong association between GSH and total Cys (R2 = 0.794). We conclude that GSH is a costly defense, especially in generalist tree‐feeding species such as L. dispar. These results further suggest that the large allocation of Cys to GSH in highly defended species might produce a tradeoff by limiting the amount of Cys available for rapid growth.
The missing teleconnection between the North Atlantic and the Sahel precipitation in CFSv2
Authors: Barandiaran Daniel , Wang Shih‐Yu 
Published: August 2013

AbstractThis study presents new findings on the link between interannual variabilities of atmospheric circulations over the North Atlantic and precipitation over the African Sahel (PS). Our analysis shows a meridionally stratified circulation wave train resembling the East Atlantic (EA) mode, apparently connected to PS through Rossby wave dispersion in the middle troposphere originating from the North Atlantic. However, the Climate Forecast System version 2 fails to depict the EA and its PS impact. Because the EA explains 29% of variance of PS, this portion of PS variability is either missing in the seasonal forecast, or being made up by an alternative process.
Studies on the interaction between vincamine and human serum albumin: a spectroscopic approach
Authors: Pu Hanlin , Jiang Hua , Chen Rongrong , Wang Hongcui 
Published: August 2013

ABSTRACTThe interaction between vincamine (VCM) and human serum albumin (HSA) has been studied using a fluorescence quenching technique in combination with UV/vis absorption spectroscopy, Fourier transform infrared (FT–IR) spectroscopy, circular dichroism (CD) spectroscopy and molecular modeling under conditions similar to human physiological conditions. VCM effectively quenched the intrinsic fluorescence of HSA via static quenching. The binding constants were calculated from the fluorescence data. Thermodynamic analysis by Van't Hoff equation revealed enthalpy change (ΔH) and entropy change (ΔS) were −4.57 kJ/mol and 76.26 J/mol/K, respectively, which indicated that the binding process was spontaneous and the hydrophobic interaction was the predominant force. The distance r between the donor (HSA) and acceptor (VCM) was obtained according to the Förster's theory of non‐radiative energy transfer and found to be 4.41 nm. Metal ions, viz., Na+, K+, Li+, Ni2+, Ca2+, Zn2+ and Al3+ were found to influence binding of the drug to protein. The 3D fluorescence, FT–IR and CD spectral results revealed changes in the secondary structure of the protein upon interaction with VCM. Furthermore, molecular modeling indicated that VCM could bind to the subdomain IIA (site I) of HSA. Copyright © 2013 John Wiley & Sons, Ltd.
Different tocopherol isoforms vary in capacity to scavenge free radicals, prevent inflammatory response, and induce apoptosis in both adult‐ and fetal‐derived intestinal epithelial cells
Authors: Elisia Ingrid , Kitts David D. 
Published: August 2013

AbstractGamma‐tocopherol (γ‐Toc) and δ‐Toc are two vitamin E isoforms for which biological activities are not well established, yet these isoforms are present in many different sources of vegetable oils and, therefore, contribute significantly to the total dietary intake of vitamin E. Infant formula also contains relatively high amounts of γ‐Toc and δ‐Toc, compared with that found in human milk. The efficacy of γ‐Toc and δ‐Toc to modulate cellular events that include oxidative stress, inflammatory response, and apoptosis‐mediated cytotoxicity, relative to α‐Toc, was determined using differentiated Caco‐2 and primary FHs 74 Int cells intestinal epithelial cell lines. Antioxidant capacity of Toc‐isoforms followed the order of δ‐Toc > γ‐Toc > α‐Toc against peroxyl radical‐induced membrane oxidation in both Caco‐2 and FHs 74 Int cells, respectively. The different Toc‐isoforms suppressed inflammatory response in interferon (IFN) γ/phorbol myristate acetate (PMA)‐induced Caco‐2 adult‐derived intestinal epithelial cells, but exacerbated both IL8 and PGE2 secretion in fetal‐derived FHs 74 Int intestinal epithelial cells. Lastly, Toc exhibited an isoform‐dependent apoptosis‐mediated cytotoxicity, whereby δ‐Toc elicited the greatest apoptosis followed by γ‐Toc, whereas α‐Toc was not cytotoxic. Cellular uptake of non‐α‐Toc isoforms were greater (P < 0.05) than that observed for α‐Toc in both intestinal epithelial cell lines which in part explains the superior bioactive function observed for both γ‐Toc and δ‐Toc, compared with α‐Toc. We conclude that the non‐α‐Toc isoforms of vitamin E have distinct roles that influence oxidative stress and inflammatory responses in both adult and fetal‐derived intestinal epithelial cell lines. © 2013 BioFactors, 39(6):663–671, 2013
Two‐dimensional liquid chromatography for direct chiral separations: a review
Authors: León‐González María Eugenia , Rosales‐Conrado Noelia , Pérez‐Arribas Luis Vicente , Guillén‐Casla Vanesa 
Published: August 2013

ABSTRACTSeparation of enantiomers remains a challenge owing to their identical physical and chemical properties in an achiral environment, and research on specialized separation techniques such as multidimensional achiral–chiral liquid chromatography continues to resolve individual enantiomers in complex samples. Recent advances in application of multidimensional liquid chromatography applied to chiral analysis are reviewed. For this reason, benefits of achiral–chiral coupling are shown, with emphasis in applications on biological and pharmaceutical fields as well as pesticide analysis. A description of standard instrumental setup in both heart‐cut and comprehensive multidimensional liquid chromatography is shown. The most broadly used chiral stationary phases for multidimensional liquid chromatography are summarized. An extensive overview of different interface designs applied to complex samples is presented. Copyright © 2013 John Wiley & Sons, Ltd.
The Antimicrobial Activity of Sub3 is Dependent on Membrane Binding and Cell‐Penetrating Ability
Authors: Torcato Inês M. , Huang Yen‐Hua , Franquelim Henri G. , Gaspar Diana D. , Craik David J. , Castanho Miguel A. R. B. , Henriques Sónia Troeira 
Published: August 2013

AbstractBecause of their high activity against microorganisms and low cytotoxicity, cationic antimicrobial peptides (AMPs) have been explored as the next generation of antibiotics. Although they have common structural features, the modes of action of AMPs are extensively debated, and a single mechanism does not explain the activity of all AMPs reported so far. Here we investigated the mechanism of action of Sub3, an AMP previously designed and optimised from high‐throughput screening with bactenecin as the template. Sub3 has potent activity against Gram‐negative and Gram‐positive bacteria as well as against fungi, but its mechanism of action has remained elusive. By using AFM imaging, ζ potential, flow cytometry and fluorescence methodologies with model membranes and bacterial cells, we found that, although the mechanism of action involves membrane targeting, Sub3 internalises inside bacteria at lethal concentrations without permeabilising the membrane, thus suggesting that its antimicrobial activity might involve both the membrane and intracellular targets. In addition, we found that Sub3 can be internalised into human cells without being toxic. As some bacteria are able to survive intracellularly and consequently evade host defences and antibiotic treatment, our findings suggest that Sub3 could be useful as an intracellular antimicrobial agent for infections that are notoriously difficult to treat.
Carbon Dioxide Reduction Catalyzed by Dinuclear Ruthenium Polypyridyl Complexes
Authors: Ono Takashi , Planas Nora , Miró Pere , Ertem Mehmed Z. , Escudero‐Adán Eduardo C. , Benet‐Buchholz Jordi , Gagliardi Laura , Cramer Christopher J. , Llobet Antoni 
Published: August 2013

AbstractDinuclear ruthenium complexes [(Ru(bid))2(μ‐bpp)(μ‐OAc)] and [(Ru(trpy))2(μ‐bpp)(μ‐X)]2+ [X=Cl−, OAc−, and OCHO−; bpp=3,5‐bis(2‐pyridyl)pyrazolato; bid−=(1Z,3Z)‐1,3‐bis(pyridin‐2‐ylmethylene)isoindolin‐2‐ide; trpy=2,2':6',2“‐terpyridine] were tested as catalysts for the hydrogenative reduction of carbon dioxide in the solvent 2,2,2‐trifluoroethanol in the presence of excess amine (triethylamine). Significant amounts of formic acid were produced by these catalysts, and a kinetic analysis based on initial rate constants was performed. These catalytic systems were investigated by using DFT calculations to elucidate the hydrogenative reduction mechanism. The results are compared with those obtained with previously reported mononuclear catalyst counterparts.
Dual pH‐ and Temperature‐Responsive Metallosupramolecular Block Copolymers with Tunable Critical Micelle Temperature by Modulation of the Self‐Assembly of NIR‐Emissive Alkynylplatinum(II) Complexes Induced by Changes in Hydrophilicity and Electrostatic Effects
Authors: Chung Clive Yik‐Sham , Yam Vivian Wing‐Wah 
Published: August 2013

AbstractTerpyridylplatinum(II)‐based metallosupramolecular triblock copolymers with hydrophilic alkynyl ligands have been synthesised and characterised. As a result of the intrinsic properties of Pluronics, reversible temperature‐induced micellisation occurred at high temperature leading to aggregation of the platinum(II) complex moieties through Pt⋅⋅⋅Pt and π–π interactions, resulting in significant UV/Vis absorption and near‐infrared (NIR) emission spectral changes. The critical micelle temperatures of the complexes were found to vary from 21 to 30 °C due to differences in the hydrophilicity of the alkynyl ligands and the electrostatic repulsions between the positively charged platinum(II) complex moieties. One of the complexes with pH‐responsive CH2NMe2 groups on the alkynyl ligand was found to show NIR emission that is sensitive to both pH and temperature. Such dual‐responsive behaviour has been ascribed to the modulation of the self‐assembly of the complex moieties by temperature‐induced micellisation and the changes in the hydrophilicity as well as electrostatic interactions upon protonation/deprotonation of the CH2NMe2 groups on the alkynyl ligand.
Synthesis of Shape‐Persistent Macrocycles with Three 1,8‐Diazaanthracene Units and Their Packing in the Single Crystal
Authors: Li Ming , Klärner Frank‐Gerrit , Sakamoto Junji , Schlüter A. Dieter 
Published: August 2013

AbstractThe synthesis of four shape‐persistent macrocycles with three 1,8‐diazaanthracene units each is reported (2,3 a–3 c). For two of them single crystals could be obtained and the structures in the crystal be solved. The structures reveal that macrocycle 2 self‐dimerizes in the solid state; surprisingly it also forms a stable dimer in solution. The reason for this is seen in unusually efficient dispersion interactions as a consequence of the large contact areas in the dimer. All macrocycles are assessed as to their applicability in lateral polymerizations in the single crystal as well as in solution.
In‐Situ Spin Labeling of His‐Tagged Proteins: Distance Measurements under In‐Cell Conditions
Authors: Baldauf Christoph , Schulze Katrin , Lueders Petra , Bordignon Enrica , Tampé Robert 
Published: August 2013

AbstractNew spin labeling strategies have immense potential in studying protein structure and dynamics under physiological conditions with electron paramagnetic resonance (EPR) spectroscopy. Here, a new spin‐labeled chemical recognition unit for switchable and concomitantly high affinity binding to His‐tagged proteins was synthesized. In combination with an orthogonal site‐directed spin label, this novel spin probe, Proxyl‐trisNTA (P‐trisNTA) allows the extraction of structural constraints within proteins and macromolecular complexes by EPR. By using the multisubunit maltose import system of E. coli: 1) the topology of the substrate‐binding protein, 2) its substrate‐dependent conformational change, and 3) the formation of the membrane multiprotein complex can be extracted. Notably, the same distance information was retrieved both in vitro and in situ allowing for site‐specific spin labeling in cell lysates under in‐cell conditions. This approach will open new avenues towards in‐cell EPR.
Reactivity of Bridged Pentelidene Complexes with Isonitriles: A New Way to Pentel‐Containing Heterocycles
Authors: Seidl Michael , Schiffer Michael , Bodensteiner Michael , Timoshkin Alexey Y. , Scheer Manfred 
Published: August 2013

AbstractThe reaction of [Cp*E{W(CO)5}2] (E=P (1 a), As (1 b); Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) with isonitriles RNC (R=tBu, cyclohexyl (Cy), nBu) depends on the steric demand of the substituent at the isonitrile as well as on the stoichiometry of the starting materials. With tBuNC only the Lewis acid/base adducts [Cp*E{W(CO)5}2(CNtBu)] (E=P (2 a), As (2 b)) are formed. The use of Cy and n‐butylisonitrile leads first to the formation of the Lewis acid/base adduct, but only at low temperatures. At ambient temperatures, a rearrangement occurs and bicyclo[3.2.0]heptane derivatives of the type [{C(Me)C(CH2)C(Me)C(Me)C(Me)}C(NR)‐ E{W(CO)5}2] (E=P, As; R=Cy, nBu) (3 a‐Cy, 3 b‐Cy, 3 a‐nBu and 3 b‐nBu) are obtained. The use of a further equivalent of isonitrile results in products revealing two new structural motifs, the four‐membered ring derivatives [C(Cp*)N(R)C(NR)E{W(CO)5}2] (4: E=P, As; R=Cy, nBu) and the bicyclic complexes [[{C(Me)C‐ (CH2)C(Me)C(Me)C(Me)}C(NR)2‐ E{W(CO)5}2] (5: E=As; R=Cy). The reaction pathway depends on the substituent at the isonitrile. By treatment of 1 a with two equivalents of CyNC only a 2H‐1,3‐azaphosphet complex 4 a‐Cy (E=P; R=Cy) is formed. Treatment of 1 b with two equivalents of CyNC exclusively leads to the complex 5 b‐Cy (E=As; R=Cy). Treatment of 1 a with two equivalents of nBuNC results in a mixture of complexes, the 2H‐1,3‐azaphosphet 4 a‐nBu (E=P; R=nBu) and the bicyclic complex 5 a‐nBu (E=P; R=nBu). For the arsenidene complex 1 b a mixture of the 2H‐1,3‐azarsete complex 4 b‐nBu (E=As; R=nBu) and the bicyclic complex 5 b‐nBu (E=P, As; R=Cy, nBu) is obtained. Complex 4 b‐nBu is the first example of a 2H‐1,3‐azarsete complex. All products have been characterized by using mass spectrometry, NMR spectroscopy, and X‐ray diffraction analysis.
Individuelle Förderung im Chemieunterricht – Der Förderkreis am Beispiel der Unterrichtseinheit „Laborführerschein“
Authors: Raguse Karola , Weber‐Peukert Gisela , Woldt Patrick , Lotz Alexander 
Published: August 2013

AbstractZiel des Beitrags ist es, Lehrerinnen und Lehrer mit einer praxistauglichen Unterrichtskonzeption vertraut zu machen, die individuelles Lernen ermöglicht und die damit verbundene Förderung von Schülerinnen und Schülern und deren Entwicklung zum selbstständigen Lerner in den Mittelpunkt stellt. Am Beispiel „Laborführerschein“ wird ein in sich konsistentes und praxistaugliches Förderkonzept vorgestellt. Über die grafische Darstellung des Förderkreismodells werden die verschiedenen Strukturelemente eines kompetenzorientierten Unterrichtsarrangements und deren Verzahnung untereinander veranschaulicht. Das mehrfach erprobte Unterrichtsarrangement ist Output orientiert und greift für Planung, Durchführung und Reflexion konsequent die Voraussetzungen der Lernenden auf. Die wiederholt diagnostizierten Lernstände fließen wiederkehrend in den Unterrichtsprozess ein und bestimmen den individuellen Lernprozess. Eine besondere Akzentuierung erfährt dabei der reflektierte Umgang mit dem Selbstkonzept der Lernenden, der Schülerinnen und Schülern helfen soll, zunehmend Verantwortung für den eigenen Lernprozess zu übernehmen.
A 2‐stage ovarian cancer screening strategy using the Risk of Ovarian Cancer Algorithm (ROCA) identifies early‐stage incident cancers and demonstrates high positive predictive value
Authors: Lu Karen H. , Skates Steven , Hernandez Mary A. , Bedi Deepak , Bevers Therese , Leeds Leroy , Moore Richard , Granai Cornelius , Harris Steven , Newland William , Adeyinka Olasunkanmi , Geffen Jeremy , Deavers Michael T. , Sun Charlotte C. , Horick Nora , Fritsche Herbert , Bast Robert C. 
Published: August 2013

BACKGROUNDA 2‐stage ovarian cancer screening strategy was evaluated that incorporates change of carbohydrate antigen 125 (CA125) levels over time and age to estimate risk of ovarian cancer. Women with high‐risk scores were referred for transvaginal ultrasound (TVS).METHODSA single‐arm, prospective study of postmenopausal women was conducted. Participants underwent an annual CA125 blood test. Based on the Risk of Ovarian Cancer Algorithm (ROCA) result, women were triaged to next annual CA125 test (low risk), repeat CA125 test in 3 months (intermediate risk), or TVS and referral to a gynecologic oncologist (high risk).RESULTSA total of 4051 women participated over 11 years. The average annual rate of referral to a CA125 test in 3 months was 5.8%, and the average annual referral rate to TVS and review by a gynecologic oncologist was 0.9%. Ten women underwent surgery on the basis of TVS, with 4 invasive ovarian cancers (1 with stage IA disease, 2 with stage IC disease, and 1 with stage IIB disease), 2 ovarian tumors of low malignant potential (both stage IA), 1 endometrial cancer (stage I), and 3 benign ovarian tumors, providing a positive predictive value of 40% (95% confidence interval = 12.2%, 73.8%) for detecting invasive ovarian cancer. The specificity was 99.9% (95% confidence interval = 99.7%, 100%). All 4 women with invasive ovarian cancer were enrolled in the study for at least 3 years with low‐risk annual CA125 test values prior to rising CA125 levels.CONCLUSIONSROCA followed by TVS demonstrated excellent specificity and positive predictive value in a population of US women at average risk for ovarian cancer. Cancer 2013;119:3454–3461.. © 2013 American Cancer Society.