bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface modification of ethylene‐vinyl alcohol copolymer treated with plasma source ion implantation
Authors: Hong Seung In , Kim Ki Beom , Lee Yeonhee , Cho Seung Yong , Ko Jung A , Hong Soon Kang , Park Hyun Jin 
Published: May 2009

AbstractThe plasma source ion implantation technique was applied to modify the surface of ethylene‐vinyl alcohol (EVOH) film using various working gases. The effects of the treated films were observed on the adhesion efficiency and physical properties. The hydrophobic properties of EVOH films were greatly enhanced after tetrafluoromethane‐plasma source ion implantation (PSII) treatment. On the other hand, the higher hydrophilic properties of EVOH films increased after oxygen‐PSII treatment. The results of X‐ray photoelectron spectroscopy showed that the improved hydrophobic or hydrophilic properties of the film were closely related to the formation of fluorine‐containing functional groups (i.e., CF, CF2, and CF3) or oxygen‐containing functional groups (i.e., CO, CO) on the modified surface. According to the result observed by atomic force microscopy, the surface roughness was not influenced on the change of contact angle. Both the peel strength and oxygen barrier property were improved in the case of CF4+O2‐PSII‐treated EVOH films. As a function of aging time, the properties of modified EVOH surfaces were maintained after PSII treatment using CF4 and O2 at the energy level of −5 kV for 1 min. When using PSII treatment, the properties of the EVOH surface were controlled by working gas and treatment conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Simultaneous determination of hydroquinone and catechol using poly(p‐aminobenzoic acid) modified glassy carbon electrode
Authors: Yang Ping , Zhu Qiyong , Chen Yonghong , Wang Fengwu 
Published: May 2009

AbstractThe electrochemical redox reaction of hydroquinone (HQ) and catechol (CC)was investigated with poly‐(p‐aminobenzoic acid) modified glassy‐carbon electrode (poly‐p‐ABA/GCE) via cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The poly‐p‐ABA/GCE has shown an excellent electrocatalytic activity for HQ and CC in 0.1 mol L−1 phosphate buffer solution (PBS). The oxidation and reduction separation (ΔE) has been decreased from 353 to 32 mV for HQ and from 228 to 33 mV vs. SCE for CC at the bare GCE and poly‐p‐ABA/GCE respectively. DPV curves show that the oxidation potential of HQ and CC has a separation about 105 mV at the poly‐p‐ABA/GCE. Moreover, the oxidation current of HQ and CC has been enhanced two and four times respectively at the modified electrode. Using DPV method, a highly selective and simultaneous determination of HQ and CC has been explored at the poly‐p‐ABA/GCE. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Aureole nanofibers by electrospinning of PAMAM‐PEO solution
Authors: Madani Mohammad , Sharifi‐Sanjani Naser , Iraji‐Rad Rasoul 
Published: May 2009

AbstractPoly(amido amine) (PAMAM) dendrimer‐polyethylene oxide (PEO) nanofibers as dendrimeric‐polymeric composite nanofibers were prepared via electrospinning of PEO solution containing PAMAM dendrimer. The resultant fibers were characterized by means of transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The morphology and thermal properties of PEO nanofibers with and without PAMAM dendrimer were compared and the effect of PAMAM concentration on morphology and thermal properties of the resultant fibers was studied. The fibers had a size range of about 400–1300 nanometer in diameter with aureole morphology in most regions. The phase change temperature, phase transition heat, and the crystallinity of the produced composite fibers were determined by DSC analyses. TGA was also used to confirm the presence of PAMAM and to determine the amount of it within the fibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Structural determination of ethylene‐propylene‐diene rubber (EPDM) containing high degree of controlled long‐chain branching
Authors: Mitra Susanta , Jørgensen Mikkel , Pedersen Walther Batsberg , Almdal Kristoffer , Banerjee Debasish 
Published: May 2009

AbstractThis work highlights an attempt to characterize the degree and nature of long‐chain branching (LCB) in an unknown sample of ethylene‐propylene‐diene rubber (EPDM). Two EPDM rubbers selected for this study were comparable in comonomer compositions but significantly different with respect to molar mass and the presence of LCB. Both rubbers contained 5‐ethylidene‐2‐norbornene (ENB) as diene. Solution cast films of pure EPDM samples were used for different characterization techniques. 1H‐NMR, and 13C‐NMR were used for assessing the comonomer ratios and LCB. Size exclusion chromatography (SEC) equipped with triple detector system was used to determine the molar mass (both absolute and relative) and polydispersity index (PDI). Presence of branching was also detected using sec‐viscometry. Rheological analysis has also been used for characterizing LCB. Finally, on the basis of the experimental findings and the available theories, an attempt was made to identify the chemical nature and degree of LCB. This study reveals the possibility of detailed characterization of molecular architecture of EPDM containing LCB by comparing with an essentially linear EPDM in light of an existing theory. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation of poly(divinylbenzene) microspheres with controllable pore structure using poly(propylene)/toluene as coporogen
Authors: Liu Qingquan , Wang Li , Xiao Anguo , Yu Haojie , Ding Jianhua , Tan Qiaohua , Huo Jia 
Published: May 2009

AbstractPoly(divinylbenzene) (poly(DVB)) microspheres with controllable pore structure were synthesized by suspension polymerization in the presence of toluene and low‐molecular weight poly(propylene) (PP) as coporogen. The weight fraction of PP in toluene varied from 0 to 20 wt %, and the feed ratio of coporogen and DVB was kept at 1/1 (vol/vol). Effects of PP weight fraction in coporogen on the specific surface area, the average pore size, the pore size distribution and the total pore volume of final microspheres were examined. As expected, poly(DVB) microspheres prepared with toluene as sole porogen had a high specific surface area (558 m2/g). Using mixtures of toluene and PP as coporogen, it was found that the specific surface area shifted higher values when low levels of PP (2.0–6.0 wt %) in toluene were used as coporogen. However, further increase of PP weight fraction in toluene resulted in progressive decline of the specific surface area. Hg intrusion/extrusion curves and N2 sorption isotherms implied caged pore structure with some small entrances. Furthermore, most of pore connectivity limitations may be eliminated when the weight fraction of PP in toluene exceeded 10.0 wt %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of clay platelet dispersion as affected by the manufacturing techniques on thermal and mechanical properties of PMMA‐clay nanocomposites
Authors: Dhibar A. K. , Mallick S. , Rath T. , Khatua B. B. 
Published: May 2009

AbstractIn this work, the properties of Poly(methyl methacrylate) (PMMA)‐clay nanocomposites prepared by three different manufacturing techniques viz., solution mixing, melt mixing, and in‐situ bulk polymerization in presence of clay were studied. Morphological analysis revealed that the extent of intercalation and dispersion of the nanoclay were relatively higher in the in‐situ polymerized nanocomposites than those of solution and melt blended nanocomposites. Differential Scanning Calorimetric study indicated maximum increment in Tg of the PMMA in the in‐situ polymerized PMMA‐clay nanocomposites. Thermo gravimetric analysis showed improved thermal stability of PMMA in all the nanocomposites and the maximum improvement was for in‐situ polymerized nanocomposites. The storage moduli of all the nanocomposites were higher than the pure PMMA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
G‐Quadruplex Aptamers with Peroxidase‐Like DNAzyme Functions: Which Is the Best and How Does it Work?
Authors: Li Tao , Dong Shaojun , Wang Erkang 
Published: May 2009

AbstractSelect the best: Five G‐quadruplex hemin‐binding aptamers are compared to determine the best candidate for DNAzyme‐based sensing application. The structural model and catalytic mechanism of the hemin–G‐quadruplex complex are proposed to indicate how it works in a manner similar to the peroxidase.magnified imageSome G‐quadruplex DNA aptamers have been found to strongly bind hemin to form DNAzymes with peroxidase‐like activity. To help determine the most suitable DNAzymes and to understand how they work, five previously reported G‐quadruplex aptamers were compared for their binding affinity and then the potential catalytic mechanism of their corresponding hemin‐G‐quadruplex DNAzymes was explored. Among these aptamers, a G‐quadruplex named AGRO100 was shown to possess the highest hemin‐binding affinity and the best DNAzyme function. This means that AGRO100 is the most ideal candidate for DNAzyme‐based analysis. Furthermore, we found the peroxidase‐like activity of DNAzyme to be primarily dependent on the concentration of H2O2 and independent of that of the peroxidase substrate (that is, 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid)diammonium salt). Accordingly, a reaction mechanism for DNAzyme‐catalyzed peroxidation is proposed. This study provides new insights into the G‐quadruplex‐based DNAzymes and will help us to further extend their applications in the analytical field.
On‐line educational tool for the parallel operation of the synchronous generators
Authors: Bekiroglu Erdal , Bayrak Alper 
Published: May 2009

AbstractThis study presents a PC and a PIC microcontroller based an on‐line educational tool for the monitoring and controlling of the parallel operation of the synchronous generators. The presented tool measures the voltages, the frequencies, the phase sequences, and the synchronism time data of the generators through microcontroller. The measured data, the voltage graphics, and the status of the parallel operation conditions are monitored on the computer instantaneously. The parallel operation of the generators is controlled with the developed tool automatically. The educational tool is user‐friendly, real‐time, reliable, and precise. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 669–677, 2011
Construction of a high‐performance computing cluster: A curriculum for engineering and science students
Authors: Chen Ming‐Huei , Li Tsung‐Lung 
Published: May 2009

AbstractIn this article, a curriculum on the construction and maintenance of a high‐performance computing cluster for students in engineering and science is presented. Laboratory sessions are an important part of this curriculum. Successive completion of the laboratory sessions automatically leads the student group to a homemade full‐functioned cluster. Students are encouraged as they see their computing cluster working at the end of the curriculum. This curriculum can be of benefit to the students who are involved with computationally intensive simulations. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 678–684, 2011
Photocatalytic Activity and Electronic Structure Analysis of N‐doped Anatase TiO2: A Combined Experimental and Theoretical Study
Authors: Gao H. , Zhou J. , Dai D. , Qu Y. 
Published: May 2009

AbstractN‐Doped TiO2 photocatalysts were prepared by a hydrothermal method with tetra‐n‐butyl titanate (TTNB) and triethanolamine as precursors. The obtained samples were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and UV‐visible diffuse reflectance spectra (DRS), respectively. Photocatalytic activities of the anatase products were investigated on the degradation of methyl orange (MO). The incorporation of nitrogen impurity in anatase TiO2 was studied by the first‐principles calculations based on the density functional theory (DFT). The calculated electronic band structures for substitutional and interstitial N‐doped TiO2 indicated the formation of localized states in the band gap, which lied above the valence band. Excitation from the impurity states of N 2p to the conduction band could account for the optical absorption edge shift toward the lower energies. It was consistent with the experimentally observed absorption of N‐doped samples in the visible region.
Exploring CFD Solutions for Coexisting Flow Regimes in a T‐Piece
Authors: Asteriadou K. , Hasting A. P. M. , Bird M. R. , Melrose J. 
Published: May 2009

AbstractThis paper presents computational fluid dynamics (CFD) models of the flow of a Newtonian fluid in a T‐piece configuration. A number of modeled flows are compared and supported by experimental work carried out using a test rig. The flows vary from laminar to turbulent, and a comparison among various kinds of mesh and models is made. The results are summarized in a mathematical expression that describes the temperature distribution down the central axis of the vertical arm as a function of known parameters of the process. Product can accumulate in stagnant unhygienic geometries and may allow growth of microorganisms that can contaminate the product flow through mass transfer. Therefore, adequate velocity and heat treatment must be ensured in these areas. Flow in such domains is difficult to solve numerically since more than one flow regime can coexist depending on the location in the domain. CFD can offer a good insight into such flows.)
Vinyl‐, Propargyl‐, and Allenylsilicon Reagents in Asymmetric Synthesis: A Relatively Untapped Resource of Environmentally Benign Reagents
Authors: Curtis‐Long Marcus J. , Aye Yimon 
Published: May 2009

AbstractGreen carbanion surrogates: Organotrialkylsilanes occupy a niche in the array of ‘green’ carbon nucleophiles open to chemists that few other reagents can fill. Despite being known for over 30 years, it is only recently that their true worth in stereoselective carbonyl addition and related processes has started to emerge, primarily due to their low reactivity. It is our hope that this minireview will make the true worth of these reagents more widely known, setting the stage for expanded usage of these versatile yet benign reagents in organic synthesis.magnified imageAn up‐to‐date in‐depth review of the current virtues and limitations in the realm of carbonyl addition reactions with allenyl‐, propargyl‐, and vinylsilicon reagents, encompassing numerous practical as well as pedagogical principles is presented. Comparisons of chemo‐, regio‐, and stereoselectivity and reactivity are drawn. Synthetic applications and challenges associated with each class of organosilane are discussed threading together the prospects of these green carbanion surrogates.
Kinetic Study of the Electro‐Catalytic Oxidation of Hydrazine on Cobalt Hydroxide Modified Glassy Carbon Electrode
Authors: HASANZADEH Mohammad , KARIM‐NEZHAD Ghasem , SHADJOU Nasrin , KHALILZADEH Balal , SAGHATFOROUSH Lotali , ERSHAD Sohrab , KAZEMAN Isa. 
Published: May 2009

AbstractElectrocatalytic oxidation of hydrazine was investigated on a cobalt hydroxide modified glassy carbon (CHM‐GC) electrode in alkaline solution. The process of oxidation involved and its kinetics were established by using cyclic voltammetry, chronoamperometry techniques as well as steady state polarization measurements. In cyclic voltammetry (CV) studies, in the presence of hydrazine the peak current increase of the oxidation of cobalt hydroxide is followed by a decrease in the corresponding cathodic current. This indicates that hydrazine is oxidized on the redox mediator that is immobilized on the electrode surface via an electrocatalytic mechanism. A mechanism based on the electrochemical generation of Co(IV) active sites and their subsequent consumption by the hydrazine in question was also investigated.
Thixotropic and Viscoelastic Properties of Hydrotalcite Like Compound‐Montmorillonite Suspensions
Authors: LI Shuping , LI Xiaodong , ZHU Yinyan 
Published: May 2009

AbstractThe thixotropic and viscoelastic properties of the complex suspension made up of hydrotalcite‐like compound (HTlc)‐sodium montmorillonite (MT) suspensions have been studied carefully. Two kinds of Fe‐Mg‐Al‐HTlc systems have been examined, and from sample 1 to sample 2, the content of Mg2+ enhances gradually while the molar ratio of Al to Fe remains constant. With increasing the content of Mg2+ in the HTlc samples, the results of the creep tests and the stress sweep experiments all indicate that the structure strength of the HTlc/MT suspension increases. Moreover, the hysterisis loops have been detected carefully, showing that the thixotropic degree increases with increasing the Mg2+ content. It was concluded that the rheological properties could be adjusted by the change of the metal content.
A Theoretical Investigation on the Reaction Mechanism of the C9H12+· Side‐chain Decomposition
Authors: CHENG Xueli , ZHAO Yanyun , LI Feng , ZHANG Dongsheng 
Published: May 2009

Abstractn‐Phenylpropane cation C9H12+· serves as a prototype to investigate the reaction mechanisms of alkylbenzene cations. The decomposition reactions of C9H12+· system have been studied extensively at the B3LYP/6‐311++G∗︁∗︁ level with Gaussian 98 program package. All reaction channels were fully investigated with the vibrational mode analysis to confirm the transition states and with electron population analysis to discuss the electron redistribution, and to elucidate the reaction mechanism. The reaction mechanism shows that there is a non‐barrier channel of C9H12+·→C7H7++C2H5·, which is thermodynamically most favorable.
A Theoretical Study on the Vibrational Spectra and Thermodynamic Properties for the Derivatives of HNS
Authors: WANG Guixiang , SHI Chunhong , GONG Xuedong , XIAO Heming 
Published: May 2009

AbstractThe derivatives of HNS were optimized to obtain their molecular geometries and electronic structures at the DFT‐B3LYP/6‐31G∗︁ level. Their IR spectra were obtained and assigned by vibrational analysis. Compared with the experimental results, all the calculated IR data were found to be reliable. Based on the frequencies scaled by 0.96 and the principle of statistic thermodynamics, the thermodynamic properties were evaluated, which are respectively linearly related with the number of nitro, amino, and hydroxy groups as well as the temperature, obviously showing good group additivity.
NMR‐based Metabonomic Study on Rat's Urinary Metabolic Response to Dosage of Triptolide
Authors: XIA Shengan , LIU Huilang , ZHU Hang , ZHOU Zhiming , ZHANG Xu , LIU Maili 
Published: May 2009

AbstractAn NMR‐based metabonomic approach was used to examine rat's urinary response to dosage of triptolide (TP), a major component responsible for the immunosuppressive and anti‐inflammatory effects of Tripterygium wilfordii Hook F (TWHF). The urine samples of Wistar rats were collected at various time intervals before and after dosage of TP (i.p.) and measured using conventional 1H NMR spectroscopy. The data were statistically analyzed using a principle component analysis (PCA). The results showed that biochemical variation induced by TP was time‐related, and the maximal alteration in the metabolites appeared at 16 h, and partially recovered 56 h later after dosage. Increment in relative concentrations of taurine, creatine, trimethylamine N‐oxide and decrement in citrate, succinate, 2‐oxoglutarate and hippurate were observed in the urine after dosage of TP. In addition, 2'‐deoxycytidine appeared 0–16 h later after the dosage, which may be considered as another biomarker for the acute hepatotoxicity. It suggested that TP may disturb the metabolism of energy and gut microflora, and may cause acute liver lesion and a slight renal impair. These results were also supported by the conventional analysis of clinical plasma chemistry and histopathology. The information observed in this article may be useful for giving insight into mechanism of liver injury induced by TP.
Determination of Bioactive Components in Polygonum perfoliatum L. by Capillary Electrophoresis with Electrochemical Detection
Authors: JIN Shuping , GUO Xifeng , ZHANG Yinyan , LI Ping , HE Pingang , WANG Qingjiang , FANG Yuzhi 
Published: May 2009

AbstractThe major bioactive components in a Chinese herb named Polygonum perfoliatum L. including ferulic acid, vanillic acid, quercetin, caffeic acid and protocatechuic acid were simultaneously determined by capillary electrophoresis with electrochemical detection (CE‐ED) in this paper. The effects of working electrode potential, pH and concentration of running buffer, separation voltage, and injection time on CE‐ED were investigated. Under the optimum conditions, the five analytes could be separated within 17 min at a separation voltage of 18 kV in 10 mmol· L−1 phosphate buffer (pH 9.2). A 300 µm diameter carbon disk electrode generated good responses at +0.95 V (vs. SCE) to the five analytes. The response was linear over three orders of magnitude with detection limits (S/N=3) ranging from 7.1×10−8 to 9.3×10−8 g·mL−1 for the analytes. This proposed method could be successfully applied to the analysis of the real samples with relatively simple extraction procedures and satisfactory results.
Site‐directed PEGylations of Thymosin α 1 Analogs and Evaluation of Their Immunoactivity
Authors: QIE Jiankun , MA Jinbo , WANG Liangyou , XU Xiaoyu , ZHOU Wenxia , QI Chunhui , ZHAO Xiunan , ZHANG Yongxiang , LIU Keliang 
Published: May 2009

AbstractPEGylation is an effective way to improve the pharmacokinetic profiles of pharmaceutical proteins or peptides. But the relatively large and long PEG chains would be likely to shelter the active site of a small peptide because of its small size, compared with a protein. Therefore, the positions and numbers of PEGylation are crucial for the bioactivity of a PEGylated peptide. To elucidate the relationship between the PEGylated positions and bioactivity of a peptide drug, site‐specific PEGylations were performed on Zadaxin (Thymosin α 1, Tα1), which is a pharmaceutical peptide with an α‐helix region, a β‐turn region, and random coils. Site‐specific mono‐PEGylations of Tα1 in different conformational regions were realized through introducing one cysteine residue into the desired positions of the peptide, followed by a coupling reaction with a thiol‐attached maleimide‐PEG reagent. Primary data from IFN‐γ production of splenocytes induced by Con A showed that the influence of PEGylation on Zadaxin was position‐dependent, and mostly, positive effects were observed after PEGylation, which indicated that the position of PEGylation is important for maintaining the bioactivity of a peptide.