bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of monodispersed silica spheres and electrospinning of poly(vinyl alcohol)/silica composite nanofibers
Authors: Wang S.H. , Sun L.G. , Zhang B. , Wang C. , Li Z.W. , He J.Z. , Zhang J. , Xie Y. 
Published: February 2011

AbstractIn this study, monodispersed silica spheres were successfully synthesized by seed‐growth method and they can be highly dispersed in the poly(vinyl alcohol)(PVA) solution. PVA/silica composite fibers were fabricated by electrospinning the composite solutions containing different amount of silica. Further investigation showed that the size distribution of silica sphere was monodispersed and the spheres were homogeneously dispersed in the fibers individually. The composite fibers showed an uniform and continuous morphology with a average diameter of 298–345 nm. The as‐spun nanofibers were characterized by Field Emission Scanning Electron Microscope (FE‐SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and thermal gravimetric analysis (TGA). POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Poly(lactic acid)/titanium dioxide nanocomposite films: Influence of processing procedure on dispersion of titanium dioxide and photocatalytic activity
Authors: Zhu Yunfeng , Buonocore Giovanna G. , Lavorgna Marino , Ambrosio Luigi 
Published: February 2011

AbstractPoly(lactic acid)/titanium dioxide (TiO2) composite films were prepared by direct melt processing using three different procedures (i.e., compression molding, twin‐screw melt extrusion, and melt extrusion and thermoforming). The effect of TiO2 loading and processing procedures on the phase morphology and on the thermal, mechanical, and barrier properties of the obtained nanocomposites were analyzed respectively by field‐emission scanning electron microscopy‐energy dispersive spectrometry, differential scanning calorimetry, universal testing machine, and water vapor and oxygen permeability measurements. The incorporation of TiO2 nanoparticles into the poly(lactic acid) matrix increased the crystallinity and improved the barrier properties of the composites. The maximum tensile strength was achieved at the 2% content of TiO2 for the films produced by compression molding and twin‐screw melt extrusion, whereas the tensile strength for films produced by melt extrusion and thermoforming decreases markedly with an increasing TiO2 content. The photocatalytic activities of the obtained nanocomposites were investigated by analyzing the degradation of methyl orange. Results confirmed that the processing procedures and the distribution of TiO2 in the polymer matrix are the key parameters, which rule the photocatalytic behavior of composite films. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Normal ranges of fetal nasal bone length during the second trimester in an Iranian population
Authors: Rahimi‐Sharbaf Fatemeh , Tahmasebpour Ahmad‐Reza , Pirjani Reihaneh , Ghaffari Saeed Reza , Rahimi‐Foroushani Abbas 
Published: February 2011

AbstractObjectiveTo provide a normal reference range for nasal bone length (NBL) during the second trimester of pregnancy in an Iranian population.MethodsThis cross‐sectional study was performed on 3201 fetuses at 15 to 28 weeks of gestational age (GA). Both singleton and twin fetuses were evaluated. The relationship between NBL and GA was determined and percentile values for each gestational week were provided.ResultsNBL measurement was obtained in 98% of singleton and 96% of twin fetuses. There was a linear relationship between GA and NBL both in singleton (R2 = 0.62) and in twin (R2 = 0.74) fetuses. There was no significant difference between twins regarding NBL (p = 0.18).ConclusionWe have provided the normal reference range for NBL during the second trimester in an Iranian population. NBL in singleton and twin fetuses is similar and there is no significant difference between twins regarding NBL. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis, characterization, and property of amphiphilic fluorinated abc‐type triblock copolymers
Authors: Guo Wenjuan , Tang XinDe , Xu Jing , Wang Xin , Chen Ye , Yu Faqi , Pei MeiShan 
Published: February 2011

AbstractNovel amphiphilic fluorinated ABC‐type triblock copolymers composed of hydrophilic poly(ethylene oxide) monomethyl ether (MeOPEO), hydrophobic polystyrene (PSt), and hydrophobic/lipophobic poly(perfluorohexylethyl acrylate) (PFHEA) were synthesized by atom transfer radical polymerization (ATRP) using N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA)/CuBr as a catalyst system. The bromide‐terminated diblock copolymers poly(ethylene oxide)‐block‐polystyrene (MeOPEO‐b‐PSt‐Br) were prepared by the ATRP of styrene initiated with the macroinitiator MeOPEO‐Br, which was obtained by the esterification of poly(ethylene oxide) monomethyl ether (MeOPEO) with 2‐bromoisobutyryl bromide. A fluorinated block of poly(perfluorohexylethyl acrylate) (PFHEA) was then introduced into the diblock copolymer by a second ATRP process to synthesize a novel ABC‐type triblock copolymer, poly(ethylene oxide)‐block‐polystyrene‐block‐poly(perfluorohexylethyl acrylate) (MeOPEO‐b‐PSt‐b‐PFHEA). These block copolymers were characterized by means of proton nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC). Water contact angle measurements revealed that the polymeric coating of the triblock copolymer (MeOPEO‐b‐PSt‐b‐PFHEA) shows more hydrophobic than that of the corresponding diblock copolymer (MeOPEO‐b‐PSt). Bovine serum albumin (BSA) was used as a model protein to evaluate the protein adsorption property and the triblock copolymer coating posseses excellent protein‐resistant character prior to the corresponding diblock copolymer and polydimethylsiloxane. These amphiphilic fluoropolymers can expect to have potential applications for antifouling coatings and antifouling membranes. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Copolymerization of 2‐hydroxyethyl methacrylate with a comonomer with spiroacetal moiety
Authors: Chiriac Aurica P. , Nita Loredana E. , Nistor Manuela T. 
Published: February 2011

AbstractThe study reports the synthesis of a copolymer based on 2‐hydroxyethyl methacrylate and 3,9‐divinyl‐2,4,8,10‐tetraoxaspiro[5.5]undecane (U) acquired through radical polymerization in the presence of 2,2′‐azobis(2‐methylpropionitrile). The attempt was to have a solid content as high as 10 wt %. The polymerization process was conducted in the presence of a classic ionic surfactant—sodium lauryl sulfate—and comparatively using two variants of protective colloid β‐cyclodextrin and poly(aspartic acid), respectively. The prepared dispersions were characterized from the viewpoint of their hydrodynamic radius, zeta potential, and conductivity evolution during syntheses. The mean particle size and size distribution and zeta potential and conductivity were also evaluated for the synthesized polymeric particles. The compositions of the polymers were confirmed by FTIR and 1H NMR spectra, and also, the thermal stability of the polymeric compounds was evaluated. SEM and AFM investigations of the polymer morphology are also presented. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Enhanced performance of photorefractive poly(N‐vinyl carbazole) composites
Authors: Tsutsumi Naoto , Dohi Akihito , Nonomura Asato , Sakai Wataru 
Published: February 2011

AbstractWe present the enhanced photorefractive performance of high molecular weight poly(N‐vinyl carbazole) (PVCz)‐based composites. Higher diffraction efficiency with faster speed of grating build‐up was obtained by optimizing the composition of the PVCz composites. At relatively low applied electric field of E = 45 V μm−1, diffraction efficiency of 26% for p‐polarized probe beam and corresponding that of 5.1% for s‐polarized probe beam were measured with faster grating build‐up speed of 48.3 s−1 for the composite with 2,4,7‐trinitrofluorenone (TNF) as a sensitizer. Fastest speed of grating build‐up of 100 s−1 and large optical gain up to 110 cm−1 were measured at E = 80 V μm−1 for the composite with fullerene derivative of PCBM as a sensitizer. These improved performances are due to a large orientational enhancement effect with faster response speed in addition to Pockels effect for the samples with appropriate glass transition temperature. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Enhanced Cellular Functions on Polycaprolactone Tissue Scaffolds by O2 Plasma Surface Modification
Authors: Yildirim Eda D. , Pappas Daphne , Güçeri Selçuk , Sun Wei 
Published: February 2011

AbstractThis paper reports a study of using an oxygen‐based plasma modification to alter physicochemical properties of three‐dimensional (3D) PCL scaffolds and to improve mouse osteoblast cells attachment, proliferation, and osteoblastic differentiation. Different plasma modification times (1, 3, and 5‐min) and their effects on surface physicochemical properties were measured by contact angle measurement, surface energy calculation (Owens–Wendth Method), surface chemistry (XPS), and the surface topography (AFM). The effect of oxygen‐based plasma modification on attachment, proliferation, and osteoblastic differentiation were examined by shear flow assay, alamarBlue assay, scanning electron microscopy (SEM), and osteoblastic differentiation markers. Results of the contact angle measurement, total solid surface energy, surface chemistry, and roughness revealed that oxygen‐based plasma modification increased surface hydrophilicity, total surface energy, total amount of oxygen containing groups, and the surface roughness. A positive effect of plasma modification on cell proliferation on 3D PCL scaffolds was observed at the osteoblastic differentiation stage which was evaluated by the alkaline phosphatase (ALP) activity, osteocalcin protein secretion, and calcium mineralization. The higher ALP activity and osteocalcin secretion were detected from the cells on 3‐min plasma modified PCL surface compared to unmodified samples. The calcium mineralization and SEM micrographs data also showed that there was a higher mineralized matrix deposition on 3‐min plasma modified PCL scaffolds compared to unmodified scaffolds. These results suggest that the 3‐min plasma modification can accelerate differentiation phase of osteoblast through improving cell–scaffold interaction. magnified image
Possible ligand release pathway of dipeptidyl peptidase IV investigated by molecular dynamics simulations
Authors: Li Cui , Shen Jie , Li Weihua , Lu Chunhua , Liu Guixia , Tang Yun 
Published: February 2011

AbstractDipeptidyl peptidase IV (DPP4) is an important target for the treatment of Type II diabetes mellitus. The crystal structure of DPP4 demonstrates that there are two possible pathways to the active site, a side opening and a β propeller opening. However, it still lacks quantitative evidence to illustrate which pathway is more favorable for inhibitor to enter into or release from the active site. In this study, conventional and steered molecular dynamics simulations were performed to explore the details of inhibitor Q448 release from the active site of DPP4 via the two potential pathways. The comparisons of force and work together with potentials of mean force results suggested that the side opening might be more favorable for the inhibitor to pass through. Moreover, Glu205‐Glu206 and Phe357 were recognized as two “key residues” in the active site for inhibitor binding. Accordingly, suggestions for further inhibitor design wereprovided. Proteins 2011; © 2011 Wiley‐Liss, Inc.
Is it really an independent protection layer?
Authors: Dowell A.M. 
Published: February 2011

AbstractLayer of protection analysis (LOPA) is a simplified chemical process risk assessment tool that is used to determine if sufficient independent protection layers (IPLs) are in place to meet an organization's risk tolerance criteria for a particular hazardous scenario. LOPA can determine how much additional risk reduction is needed for the scenario and can help in specifying the additional protection layers.The Center for Chemical Process Safety books, Layer of Protection Analysis—Simplified Process Risk Assessment (Center for Chemical Process Safety, Layer of Protection Analysis: Simplified Process Risk Assessment, American Institute of Chemical Engineers, New York, NY, 2001) and Guidelines for Safe and Reliable Instrumented Protective Systems (Center for Chemical Process Safety, Guidelines for Safe and Reliable Instrumented Protective Systems, American Institute of Chemical Engineers, New York, NY, 2007), identify required attributes of independent protective layers. In more than 15 years experience working with LOPA, I have frequently observed confusion about these attributes among LOPA analysts, protection layer implementers, and operations personnel (Study and Champion, Process Saf Prog 28 (2009), 300–307).Therefore, this article discusses the characteristics of IPLs, gives examples to avoid confusion and misapplication of the characteristics, gives an easily remembered phrase to screen candidate IPLs, and provides sample tools to confirm IPL compliance with the characteristics. The article discusses the importance of a safety requirements specification for safety‐instrumented functions and proposes analogous documentation for other IPLs. The article gives guidance to determine when protection layers or scenarios require more detailed analysis such as event tree analysis or fault tree analysis. analysis. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2011
Improving operational discipline to prevent loss of containment incidents
Authors: Vaughen Bruce K. , Klein James A. 
Published: February 2011

AbstractProcess safety and risk management systems are implemented to reduce injuries and process incidents. The effectiveness of these systems is dependent on the company's implementation and support for operational discipline (OD)‐related programs to ensure that the process safety management system requirements are followed day‐to‐day at all levels of the organization. However, OD‐program‐related problems continue to contribute to process incidents, including loss of containment (LOC) incidents, especially since they may not be formally addressed during incident investigations. This article provides a brief historical overview of major LOC incidents, describes how poor OD increases process safety risk and can contribute to LOC incidents, and provides an incident investigation tool to help monitor and improve OD characteristics. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2011
Analogues of trypsin inhibitor SFTI‐1 modified in the conserved P1′ position by synthetic or non‐proteinogenic amino acids retain their inhibitory activity
Authors: Rafał Łukajtis , Anna Łȩgowska , Magdalena Wysocka , Dawid Dȩbowski , Adam Lesner , Krzysztof Rolka 
Published: February 2011

AbstractA series of linear and monocyclic (with a disulfide bridge only) analogues of trypsin inhibitor SFTI‐1 modified in the P1 and/or P1′ positions were synthesized by the solid‐phase method. In the substrate specificity P1 position, Phe or N‐benzylglycine (Nphe) were introduced, whereas the conserved Ser6 in Bownam‐Birk (BBI) inhibitors was replaced by Hse (L‐homoserine), Nhse [N‐(2‐hydroxyethyl)glycine], Sar, and Ala. Kinetic studies of interaction of the analogues with bovine α‐chymotrypsin have shown that in monocyclic (but not linear) analogues, Hse and Nhse are tolerated to afford potent inhibitors. This is the first evidence that the absolutely conserved Ser present in the inhibitor's P1′ position can be successfully replaced by a synthetic derivative. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
Meteorological observations on Dun Fell, a mountain station in Northern England
Authors: Manley Gordon 
Published: February 2011

AbstractMeteorological observations have been kept lor three years 1937–40 on the exposed summit of Dun Fell in the Northern Pennines, including a continuous record of temperature. In a semi‐maritime climate this mountain station at 2,735 ft. is well above the tree‐line and conditions are at times severe. Estimates of the longer‐period averages are made for several climatic elements and compared with those from summit stations elsewhere. It is emphasised that over longer periods of time considerable variations in the upland climate are likely to occur as a result of small changes in the average distribution of pressure and that these will react considerably upon the vegetation. Although this record was initiated for other reasons and is unpretentious in scope it may be added that this is the first series of “mountain” observations to become available in England.
Condensation caused by mixing
Authors: Petterssen Sverre 
Published: February 2011

AbstractThe rǒle of mixing in the production of fogs and clouds has been the subject of frequent discussions, and many authors contend that turbulent mixing is an important factor in the formation of fog. This result is derived from the well‐known Bezold effect and supported by observations showing that fogs sometime occur together with winds of considerable strength. The writer (1939, 1940, 1941) has maintained that turbulent mixing tends to prevent fogs from forming and dispel existing fogs. The aim of this paper is to evaluate the amounts of condensation caused by mixing under various atmospheric conditions. Throughout it will be assumed that the air contains a sufficient amount of condensation nuclei, with the result that no appreciable supersaturation can be maintained.
The problem of auto‐correlation of meteorological time series, illustrated by examples from some South African stations
Authors: Schumann T. E. W. , Hofmeyer W. L. 
Published: February 2011

AbstractThe main object of this paper is to present a number of characteristic values of the auto‐correlation coefficient as actually computed from observed series of temperature and pressure. For this purpose the temperature and pressure records of some South African stations were selected.In the case of temperatures, it was found that, provided any daily or seasonal fluctuations are first eliminated and the standard deviation is constant, the coefficient of auto‐correlation R' has the analytic form R' = e‐ky, in which k is a constant and y is the time‐lag. If, however, there is a marked variation in the standard deviation, such as is nearly always present in hourly values of temperature, R' is a function not only of the time‐lag, but also of the actual times marking the beginning and end of the time‐lag under consideration.In the case of a series of pressure readings R' is not a simple exponential function, but may contain one or more damped harmonic terms.
Measurement of 13C and 15N isotope labeling by gas chromatography/combustion/isotope ratio mass spectrometry to study amino acid fluxes in a plant–microbe symbiotic association
Authors: Molero Gemma , Aranjuelo Iker , Teixidor Pilar , Araus José Luis , Nogués Salvador 
Published: February 2011

AbstractWe have developed a method based on a double labeling with stable isotopes and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) analyses to study amino acid exchange in a symbiotic plant–microbe association. Isotopic precision was studied for 21 standards including 15 amino acid derivatives, three N‐protected amino acid methyl esters, three amines and one international standard. High correlations were observed between the δ13C and δ15N values obtained by GC/C/IRMS and those obtained by an elemental analyzer (EA) coupled to an isotope ratio mass spectrometer (R2 = 0.9868 and 0.9992, respectively). The mean precision measured was 0.04‰ for δ13C and 0.28‰ for δ15N (n = 15). This method was applied in vivo to the symbiotic relationship between alfalfa (Medicago sativa L.) and N2‐fixing bacteria. Plants were simultaneously labeled over 10 days with 13C‐depleted CO2 (12CO2), which was assimilated through photosynthesis by leaves, and 15N2 fixed via nodules. Subsequently, the C and N isotope compositions (i.e. δ13C and δ15N) of free amino acids were analyzed in leaves and nodules by GC/C/IRMS. The method revealed the pattern of C and N exchange between leaves and nodules, highlighting that γ‐aminobutanoic acid and glycine may represent an important form of C transport from leaves to the nodules. The results confirmed the validity, reliability and accuracy of the method for assessing C and N fluxes between plants and symbiotic bacteria and support the use of this technique in a broad range of metabolic and fluxomic studies. Copyright © 2011 John Wiley & Sons, Ltd.
Absorption and translocation of nitrogen in rhizomes of Leymus chinensis
Authors: Liu Hongsheng , Liu Huajie , Song Youhong 
Published: February 2011

AbstractLeymus chinensis is a dominant species in the Inner Mongolia steppe, northern China. Plant growth in northern China grassland is often limited by low soil nitrogen availability. The objective of this study is to investigate whether rhizomes of Leymus chinensis are involved in the contribution of N uptake. The N concentration, 15N concentration and 15N proportion in roots, rhizomes and shoots after 48 h exposure of roots (Lroot) and rhizomes (Lrhizo) separately and roots and rhizomes together (Lr+r) to 0.1 mM 15NHNO3 solution were measured using root‐splitting equipment and stable isotope (15N) techniques, respectively. The N content and dry mass were not affected by the labeling treatment. In contrast, the 15N concentration in shoots, rhizomes and roots was significantly increased by the labeling in rhizomes, indicating that the inorganic nitrogen was absorbed via rhizomes from the solution and can be transported to other tissues, with preference to shoots rather than roots. Meanwhile, the absolute N absorption and translocation among compartments were also calculated. The N absorption via rhizomes was much smaller than via roots; however, the uptake efficiency per surface unit via rhizomes was greater than via roots. The capacity and high efficiency to absorb N nutrient via rhizomes enable plants to use transient nutrient supplies in the top soil surface. Copyright © 2011 John Wiley & Sons, Ltd.
Charging megadalton poly(ethylene oxide)s by electrospray ionization. A charge detection mass spectrometry study
Authors: Doussineau Tristan , Kerleroux Michel , Dagany Xavier , Clavier Christian , Barbaire Marc , Maurelli Jacques , Antoine Rodolphe , Dugourd Philippe 
Published: February 2011

AbstractIons from compounds of megadalton (MDa) molecular weight were produced in an electrospray ionization source from solutions of poly(ethylene oxide) (PEO) samples with average molecular weights ranging from 1 000 000 to 7 000 000 Da. Charge detection mass spectrometry (CDMS) has been used to determine the mass of the MDa PEOs. Simultaneous measurement of the charge and velocity of individual ions allows the mass determination of the ion, after calibration of the instrument with independent samples. In addition to the mass spectra, CDMS generates charge‐versus‐mass plots, which allow investigation of the charging of electrosprayed ions over a broad range of masses. The experimental charging capacity of MDa PEOs is compared with a simple model based on the affinity of alkali cations for oxygen sites and on the electrostatic potential energy of the charged polymer. The charging capacity of PEOs was also investigated as a function of the concentration of and the type of alkali ions. Copyright © 2011 John Wiley & Sons, Ltd.