bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relaxation behavior of poly(lactic acid)/poly(butylene succinate) blend and a new method for calculating its interfacial tension
Authors: Xu Lin‐Qiong , Huang Han‐Xiong 
Published: April 2012

AbstractThe biomass‐based blend of 80/20 (w/w) poly(lactic acid)/poly(butylene succinate) (PLA/PBS) is prepared using an extruder. The prepared blend shows a typical droplet‐matrix morphology. The relaxation behavior of the blend is investigated in terms of storage modulus, loss tangent, and Cole–Cole plots. In the low frequency region, the blend exhibits higher elastic indices than the pure components on the storage modulus and loss tangent curves, and remarkable deviation from a semicircular shape on the Cole–Cole plot. These features are thought to arise from the relaxation of the deformed droplets. The loss tangent curve is more sensitive to the relaxation behavior of the deformed droplets than the storage modulus curve. Moreover, the complex viscosity of the blend is separated into real and imaginary parts to further analyze its relaxation behavior. Three relaxation times for the blend are defined on the curve of the imaginary part of the viscosity. It is demonstrated that the reciprocal of the frequency corresponding to the peak in the low frequency region on the imaginary part curve is equal to the longest relaxation time of the blend obtained from the storage modulus curve. Based on this result, a new method is proposed to calculate the interfacial tension between the PLA and PBS in the blend, which is 3.7 mN/m. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Fiber‐reinforced nanopigmented poly(methyl methacrylate) as improved denture base
Authors: Moreno‐Maldonado V. , Acosta‐Torres L. S. , Barceló‐Santana F. H. , Vanegas‐Lancón R. D. , Plata‐Rodríguez M. E. , Castaño V. M. 
Published: April 2012

AbstractNanopigmented and fiber‐reinforced poly (methyl methacrylate) (PMMA) were synthesized for denture bases, by incorporating E‐glass fibers, flock fibers, or polyethylene fibers into the PMMA powder formulation to improve the flexural behavior and porosity; decreasing the Candida albicans adherence and being noncytotoxic. The commercial acrylic resin, Lucitone 199 was used as a control group. Scanning electron microscopy analysis was performed to the PMMA particles and the reinforcing fibers. Flexural strength increased by adding E‐glass fibers in the PMMA powder as compared to flock and polyethylene fibers. The reinforced PMMA with flock fibers showed the lower porosity even smaller than Lucitone 199. The synthesized PMMA and the fiber reinforced nanopigmented PMMA groups reduced significantly the C. albicans adherence when compared to the commercial acrylic resin. All the tested groups were found to be nontoxic materials after being in contact with mouse fibroblast culture during 24 h, showing that these novel nanostructured composites are suitable for producing adequate and nontoxic reinforced materials with antimicrobial properties for dentistry applications. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Preparation and characterization of cellulose‐coated chitosan beads with improved strength and acid resistivity
Authors: Duan Jiangjiang , Wang Yue , Wang Yudi , Xiong Xiaopeng 
Published: April 2012

AbstractA new chitosan bead was successfully prepared by simply dropping acidic chitosan solution into 0.5 wt % alkaline cellulose solution. The X‐ray photoelectron spectroscopy analysis and the scanning electron microscope observation indicate that thin layer of cellulose was coated on the chitosan bead to have strong interaction with inner chitosan. Therefore, the bead reveals porous microstructure of regenerate cellulose in the surface. Owing to the cellulose coating, the bead displays improved mechanical properties and acid resistance. The adsorption of Fe3+ onto the new chitosan beads was investigated in detail, and the results show that the cellulose coating has little influence on the adsorption of the chitosan. Therefore, this study provides a novel method to expand the application of chitosan by coating with an acid‐insensitive polymer. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Elution of polymers from poly(vinyl alcohol) cast gels with different degrees of polymerization and hydrolysis
Authors: Sasaki Saori , Otsuka Emiko , Hirashima Yumiko , Suzuki Atsushi 
Published: April 2012

AbstractPoly(vinyl alcohol) (PVA) gels physically crosslinked by microcrystallites were prepared by a cast‐drying method using PVA powders with different degrees of polymerization (nDP) between 300 and 2400 and hydrolysis (rDH) between 79.5 and 98.5 mol %. Polymer elution of gels in a limited amount of water was investigated by measuring the total carbon in the outer water by a total organic carbon analyzer. As a result, polymer elution was detected for all gels, the total amount of which depended on both nDP and rDH. In the cases of lower nDP and higher rDH, the gel became opaque and cracks were observed on the surface during a simple swelling process. On the other hand, polymers dissolved without cracks in the cases of higher nDP and lower rDH. These results are discussed on the basis of the network microstructure of the dried states before and after the polymer elution. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Investigation of the effect of double‐walled carbon nanotubes on the curing reaction kinetics and shear flow of an epoxy resin
Authors: El Sawi Ihab , Olivier Philippe A. , Demont Philippe , Bougherara Habiba 
Published: April 2012

AbstractIn this article, the effect of combined temperature‐concentration and shear rate conditions on the rheology of double‐walled carbon nanotubes (DWCNTs)/RTM6‐Epoxy suspension was investigated to determine the optimum processing conditions. The rheological behavior and cure kinetics of this nanocomposite are presented. Cure kinetics analysis of the epoxy resin and the epoxy resin filled with DWCNTs was performed using Differential Scanning Calorimeter (DSC) and parameters of the kinetics model were compared. The DWCNTs have an acceleration effect on the reaction rate of the epoxy resin but no significant effect is noted on the glass transition temperature of the epoxy resin. This study reveals that the effect of shear‐thinning is more pronounced at high temperatures when DWCNTs content is increased. In addition, the steady shear flow exhibits a thermally activated property above 60°C whereas the polymer fluid viscosity is influenced by the free volume and cooperative effects when the temperature is below 60°C. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Study of physicochemical properties of two current commercial dental self‐curing resin composites
Authors: Sideridou Irini D. , Vouvoudi Evangelia C. , Bourdouni Konstantina A. 
Published: April 2012

AbstractThe aim of the present work is the study of some physicochemical properties of two current commercial dental self‐curing two component composites, i.e., of Concise™ (3M™, Dental Products, St. Paul, USA), and Alfacomp (VOCO GmbH, Germany). Based on their filler type Concise is characterized as “conventional” or “macrofilled” composite and Alfacomp as “hybrid.” The resin matrix of Concise is a copolymer of 2‐bis[4‐2‐hydroxy‐3‐(methacryloxy)‐propyl]phenyl propane (Bis‐GMA)/triethyleneglycol dimethacrylate, while that of Alfacomp a homopolymer of Bis‐GMA. The composites were prepared in accordance with the manufacturers' instructions by mixing equal amounts of the two components at room temperature. The degree of conversion of double bonds of resin matrix during curing was determined in thin film of composites using FTIR transmission spectroscopy. The degree of conversion of Concise and Aflacomp was found to be correspondingly (73.63 ± 4.33)% and (47.75 ± 1.80)% after a day‐polymerization. Sorption, solubility, and volumetric change were determined after storage of composites in water or ethanol/water solution 75 vol % at 37°C (a good food/oral simulating fluid) for 30 days. These properties for both composites were higher in ethanol/water solution than in water. Also these properties for Concise were lower than those for Alfacomp in both liquids. Thermal stability of composites was studied by thermogravimetric analysis which performed in air atmosphere from 50 to 800°C. This analysis of composites showed the degradation of their resin matrix in three steps. The organic resin content of Concise was found to be 18.0% w/w and that of Alfacomp 20.1% w/w. Concise showed generally better properties than Alfacomp. This behavior must due to the differences in the chemical structure of the organic resin matrix and the type of inorganic filler. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Thermodynamic parameters of poly(ethylene glycol) from dielectric relaxation studies
Authors: Sannaningannavar F. M. , Navati B. S. , Ayachit N. H. 
Published: April 2012

AbstractThermodynamic parameters, like change in free energy of activation (ΔG), enthalpy of activation (ΔH), and entropy of activation (ΔS) of poly(ethylene glycol) with average molecular mass 400 Delton (PEG 400) in dilute solution of benzene were computed on the basis of theory of Eyring rate process. To estimate these, the dielectric relaxation time (τ), determined at various temperatures adopting Whiffen and Thompson model have been used. X‐band microwave bench working at 9.59 GHz was employed to find temperature dependent real part ε′ of the complex dielectric permittivity ε* and dielectric loss ε″. The values of these ε′ and ε″ are used to find τ values. Based on the results reported, the relaxation behavior of the stated polymer in nonpolar solvent is discussed. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Lamellarins as Inhibitors of P‐Glycoprotein‐Mediated Multidrug Resistance in a Human Colon Cancer Cell Line
Authors: Plisson Fabien , Huang Xiao‐Cong , Zhang Hua , Khalil Zeinab , Capon Robert J. 
Published: April 2012

AbstractChemical analysis of a Didemnum sp. (CMB‐01656) collected during scientific Scuba operations off Wasp Island, New South Wales, yielded five new lamellarins A1 (1), A2 (2), A3 (3), A4 (4) and A5 (5) and eight known lamellarins C (6), E (7), K (8), M (9), S (10), T (11), X (12) and χ (13). Analysis of a second Didemnum sp. (CMB‐02127) collected during scientific trawling operations along the Northern Rottnest Shelf, Western Australia, yielded the new lamellarin A6 (14) and two known lamellarins G (15) and Z (16). Structures were assigned to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 on the basis of detailed spectroscopic analysis with comparison to literature data and authentic samples. Access to this unique library of natural lamellarins (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16) provided a rare opportunity for structure–activity relationship (SAR) investigations, probing interactions between lamellarins and the ABC transporter efflux pump P‐glycoprotein (P‐gp) with a view to reversing multidrug resistance in a human colon cancer cell line (SW620 Ad300). These SAR studies, which were expanded to include the permethylated lamellarin derivative (17) and a series of lamellarin‐inspired synthetic coumarins (19, 20, 21, 22, 23, 24) and isoquinolines (25, 26), successfully revealed 17 as a promising new non‐cytotoxic P‐gp inhibitor pharmacophore.
1‐Bromo‐2‐(cyclopropylidenemethyl)benzene: A Useful Building Block in the Palladium‐Catalyzed Reaction of 2‐Alkynylbenzenamine
Authors: Li Shaoyu , Luo Yong , Wang Xiaocong , Guo Minjie , Wu Jie 
Published: April 2012

AbstractA novel palladium‐catalyzed domino reaction of 1‐bromo‐2‐(cyclopropylidenemethyl)benzene and 2‐alkynylbenzenamine is reported, which generates 2‐(naphthalen‐2‐yl)benzenamines and 5H‐indeno[1,2‐c]quinolines via 6‐endo and 5‐exo cyclization, respectively. The regioselectivity for the final outcome can be affected by phosphine and N‐heterocyclic carbene ligands.
Protein oxidation in Huntington disease
Authors: Sorolla M. Alba , Rodríguez‐Colman María José , Vall‐llaura Núria , Tamarit Jordi , Ros Joaquim , Cabiscol Elisa 
Published: April 2012

AbstractHuntington disease (HD) is an inherited neurodegenerative disorder caused by expansion of CAG repeats in the huntingtin gene, affecting initially the striatum and progressively the cortex. Oxidative stress, and consequent protein oxidation, has been described as important to disease progression. This review focuses on recent advances in the field, with a particular emphasis on the identified target proteins and the role that their oxidation has or might have in the pathophysiology of HD. Oxidation and the resulting inactivation and/or degradation of important proteins can explain the impairment of several metabolic pathways in HD. Oxidation of enzymes involved in ATP synthesis can account for the energy deficiency observed. Impairment of protein folding and degradation can be due to oxidation of several heat shock proteins and Valosin‐containing protein. Oxidation of two enzymes involved in the vitamin B6 metabolism could result in decreased availability of pyridoxal phosphate, which is a necessary cofactor in transaminations, the kynurenine pathway and the synthesis of glutathione, GABA, dopamine and serotonin, all of which have a key role in HD pathology. In addition, protein oxidation often contributes to oxidative stress, aggravating the molecular damage inside the cell.
Gorgon and pathwalking: Macromolecular modeling tools for subnanometer resolution density maps
Authors: Baker Matthew L. , Baker Mariah R. , Hryc Corey F. , Ju Tao , Chiu Wah 
Published: April 2012

AbstractThe complex interplay of proteins and other molecules, often in the form of large transitory assemblies, are critical to cellular function. Today, X‐ray crystallography and electron cryo‐microscopy (cryo‐EM) are routinely used to image these macromolecular complexes, though often at limited resolutions. Despite the rapidly growing number of macromolecular structures, few tools exist for modeling and annotating structures in the range of 3–10 Å resolution. To address this need, we have developed a number of utilities specifically targeting subnanometer resolution density maps. As part of the 2010 Cryo‐EM Modeling Challenge, we demonstrated two of our latest de novo modeling tools, Pathwalking and Gorgon, as well as a tool for secondary structure identification (SSEHunter) and a new rigid‐body/flexible fitting tool in Gorgon. In total, we submitted 30 structural models from ten different subnanometer resolution data sets in four of the six challenge categories. Each of our utlities produced accurate structural models and annotations across the various density maps. In the end, the utilities that we present here offer users a robust toolkit for analyzing and modeling protein structure in macromolecular assemblies at non‐atomic resolutions. © 2012 Wiley Periodicals, Inc. Biopolymers 97: 655–668, 2012.
Quality attributes of recombinant therapeutic proteins: An assessment of impact on safety and efficacy as part of a quality by design development approach
Authors: Eon‐Duval Alex , Broly Hervé , Gleixner Ralf 
Published: April 2012

AbstractQuality by Design (QbD) is a new approach to the development of recombinant therapeutic protein products that promotes a better understanding of the product and its manufacturing process. The first step in the QbD approach consists in identifying the critical quality attributes (CQA), i.e., those quality attributes of the product that have an impact on its clinical efficacy or safety. CQAs are identified through a science‐based risk assessment taking into consideration a combination of clinical and nonclinical data obtained with the molecule or other similar molecules or platform products, as well as the published literature. The purpose of this article is to perform a comprehensive review of the published literature, supporting an assessment of the impact on safety and efficacy of the quality attributes commonly encountered in recombinant therapeutic proteins, more specifically those produced in mammalian cell expression systems. Quality attributes generally observed in biopharmaceutical proteins including product‐related impurities and substances, process‐related impurities, product attributes, and contaminants are evaluated one by one for their impact on biological activity, pharmacokinetics and pharmacodynamics, immunogenicity, and overall safety/toxicity. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012
Popliteal vascular entrapment syndrome caused by variant lateral head of the gastrocnemius muscle leading to pulmonary artery embolism
Authors: Wang Maohua , Zhang Shiyi , Wu Xuejun , Jin Xing , Zhang Jingyong 
Published: April 2012

AbstractA young man with popliteal vascular entrapment syndrome (PVES) presented with arterial occlusion, deep venous thrombosis (DVT), pulmonary artery embolism, and pulmonary hypertension. He received computer tomography (CT) and magnetic resonance imaging (MRI). Both CT and MRI showed that the left thrombosed popliteal vein and artery were entrapped by a variant lateral head of the gastrocnemius muscle. The anomalous slip originated from the lateral head of left gastrocnemius muscle and ended between the medial and lateral femoral condyles. PVES Type V was diagnosed. Compression of the popliteal vein without arterial compression can be explained by the more lateral location of the popliteal vein relative to the artery and its proximity to the lateral head of the gastrocnemius. Compression of the popliteal vein with arterial compression was found in this patient. Compression of popliteal vein and artery in this patient led to DVT and arterial occlusion. The case was the first reported case accompanied by popliteal vein and artery thrombosis caused by variant lateral head of the gastrocnemius muscle. Radiologists and doctors should continue to look for possible abnormalities in the popliteal fossa in young patients with peripheral vascular disease because early diagnosis of PVES allows better choices and outcomes of treatment. Clin. Anat. 25:986–988, 2012. © 2012 Wiley Periodicals, Inc.
The ancient Hellenic and Hippocratic origins of head and brain terminology
Authors: Panourias Ioannis G. , Stranjalis George , Stavrinou Lampis , Sakas Damianos E. 
Published: April 2012

AbstractCorpus Hippocraticum, a collection of Hippocratic writings, is considered to be the first written monument of rationale medicine. This article focuses on a series of ancient Hellenic words which are cited in Hippocratic passages and have been adopted in current head and brain terminology either invariably, i.e., keeping their original meaning, or as component parts of newly formed terms. This study aims to demonstrate first that the deeper roots of current neuroanatomical terminology spread in Hippocratic writings and second, that ancient Hellenic remains a living language that would probably ever continue to play a catalytic role in the formation of neuroanatomical glossary by providing accurate, emblematic, and functional terms. Clin. Anat. 25:548–558, 2012. © 2012 Wiley Periodicals, Inc.
Generation of RNA Molecules by a Base‐Catalysed Click‐Like Reaction
Authors: Costanzo Giovanna , Saladino Raffaele , Botta Giorgia , Giorgi Alessandra , Scipioni Anita , Pino Samanta , Di Mauro Ernesto 
Published: April 2012

AbstractThe problem of the abiotic origin of RNA from prebiotically plausible compounds remains unsolved. As a potential partial solution, we report the spontaneous polymerization of 3′,5′‐cyclic GMP in water, in formamide, in dimethylformamide, and (in water) in the presence of a Brønsted base such as 1,8‐diazabicycloundec‐7‐ene. The reaction is untemplated, does not require enzymatic activities, is thermodynamically favoured and selectively yields 3′,5′‐bonded ribopolymers containing as many as 25 nucleotides. We propose a reaction pathway on the basis of 1) the measured stacking of the 3′,5′‐cyclic monomers, 2) the activation by Brønsted bases, 3) the determination (by MALDI‐TOF mass spectrometry, by 31P NMR, and by specific ribonucleases) of the molecular species produced. The reaction pathway has several of the attributes of a click‐like reaction.
Middle‐of‐the‐night PCI does not affect subsequent day PCI success and complication rates by the same operator
Authors: Crudu Vitalie , Sartorius Jennifer , Berger Peter , Scott Thomas , Skelding Kimberly , Blankenship James 
Published: April 2012

AbstractObjectiveTo determine the impact of percutaneous coronary interventions (PCI) performed during late‐night hours on next day PCI performance by the same interventional cardiologist.BackgroundThere is little data regarding the effects of sleep deprivation on interventional cardiologists performing PCIs.MethodsAll primary PCIs from January 1, 2005 to December 31, 2009 between 11 PM and 7 AM were identified. All PCIs performed during the subsequent work day by the same interventionists were included in the sleep‐deprived group. All other PCIs were included in the non‐sleep‐deprived group. Data were entered prospectively into the American College of Cardiology National Cardiovascular Data Registry (NCDR). The two groups were compared with respect to efficacy and safety endpoints.ResultsDuring the 5‐year period, 3,944 PCIs were performed by four operators, including 3,644 non‐sleep‐deprived cases and 167 sleep‐deprived cases. The two groups were similar with respect to demographics, comorbidities, and procedural characteristics. There were more intraprocedural deaths in the sleep‐deprived group (1.2% vs. 0.2%, P = 0.04); however, the adjusted odds ratio (OR) was nonsignificant (OR = 6.83, 95% confidence interval [CI] = 0.66–39.63, P = 0.11). Excessive bleeding at the arterial access site in the non‐sleep‐deprived group was more frequent (2.7% vs. 0%, P = 0.02). There were no differences in the combined safety or efficacy endpoints between the two groups.ConclusionIn this single‐center study, we found no evidence that middle‐of‐the night procedures adversely affect safety or efficacy of procedures done the next day by the same operator. © 2012 Wiley Periodicals, Inc.
A Solid‐State Combustion Method towards Metallic Cu–ZnO Catalyst without Further Reduction and its Application to Low‐Temperature Methanol Synthesis
Authors: Shi Lei , Tan Yi‐sheng , Tsubaki Noritatsu 
Published: April 2012

AbstractA series of Cu–ZnO catalysts were prepared by using a solid‐state combustion method with metal nitrates and citric acid. This method was simple, waste water free, and did not require a reduction step. If the precursors were burnt in an argon atmosphere, H2 and CH4 were emitted in the decomposition of metal citrate complexes and acted as reducing agents to yield metallic Cu from Cu2+ in the chelated compounds. Analysis of XRD patterns revealed that the precursors burnt at 523 K for 1 h in the argon atmosphere were converted into pure Cu species. TPR analysis of the burnt catalysts without further reduction illustrated that almost no hydrogen was consumed. However, a part of amorphous carbon and carboxylates were left in the burnt catalysts. Compared with formerly reported Cu–ZnO catalysts prepared by the sol–gel combustion method, the catalysts prepared by the solid‐state combustion method had higher activity and methanol selectivity.
Fabrication of Homogenous Polymer‐Zeolite Nanocomposites as Mixed‐Matrix Membranes for Gas Separation
Authors: Karkhanechi H. , Kazemian H. , Nazockdast H. , Mozdianfard M. R. , Bidoki S. M. 
Published: April 2012

AbstractInterfacial void‐free mixed‐matrix membranes (MMMs) of polyimide (PI)/zeolite were developed using 13X and Linde type A nano‐zeolites and tested for gas separation purposes. Fabrication of a void‐free polymer‐zeolite interface was verified by the decreasing permeability developed by the MMMs for the examined gases, in comparison to the pure PI membrane. The molecular sieving effect introduced by zeolite 13X improved the CO2/N2 and CO2/CH4 selectivity of the MMMs. Separation tests indicated that the manufactured nanocomposite membrane with 30 % loading of 13X had the highest permselectivity for the gas pairs CO2/CH4 and CO2/N2 at the three examined feed pressures of 4, 8 and 12 atm.