bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical and Electronic NOx Sensors for Applications in Mechatronics
Authors: Di Franco Cinzia , Elia Angela , Spagnolo Vincenzo , Scamarcio Gaetano , Lugarà Pietro Mario , Ieva Eliana , Cioffi Nicola , Torsi Luisa , Bruno Giovanni , Losurdo Maria , Garcia Michael A. , Wolter Scott D. , Brown April , Ricco Mario
Published: May 2009

Current production and emerging NOx sensors based on optical and nanomaterials technologies are reviewed. In view of their potential applications in mechatronics, we compared the performance of: i) Quantum cascade lasers (QCL) based photoacoustic (PA) systems; ii) gold nanoparticles as catalytically active materials in field-effect transistor (FET) sensors, and iii) functionalized III-V semiconductor based devices. QCL-based PA sensors for NOx show a detection limit in the sub part-per-million range and are characterized by high selectivity and compact set-up. Electrochemically synthesized gold-nanoparticle FET sensors are able to monitor NOx in a concentration range from 50 to 200 parts per million and are suitable for miniaturization. Porphyrin-functionalized III-V semiconductor materials can be used for the fabrication of a reliable NOx sensor platform characterized by high conductivity, corrosion resistance, and strong surface state coupling.
Preparation and characterization of nylon610/functionalized multiwalled carbon nanotubes composites
Authors: Li Zhongyuan , Xu Shuzhen , Liu Wentao , He Suqin , Zhu Chengshen
Published: May 2009

Nylon610 nanocomposites containing functionalized multiwalled carbon nanotubes (MWCNTs) were prepared using wet melt blending method, which is a novel preparation technique. In comparison with the pure nylon610, the elastic modulus, tensile strength, bending modulus, and bending strength of the composites increase significantly with the increase of MWCNTs content, and the mechanical properties of the composites are also improved significantly by adding a small amount of MWCNTs (0.1 wt %). The crystallization peak of the composites shifts to higher temperature with the addition of MWCNTs, and among the two melting peaks, the intensity of melting peak at low temperature decreases with increasing MWCNTs content. The composites are more stable than pure PA610 and decompose at higher temperature, suggesting that the accession of MWCNTs can improve the composites' thermal stability. The storage modulus of the composites decreases with the temperature increasing, but under lower temperature it increases significantly with the addition of MWCNTs–COOH except for PANT‐0.1 sample. Transmission electron microscope (TEM) images of composites exhibit that the wet melt blending technique can avoid the excess agglomeration of MWCNTs under vacuum dryness, which benefits MWCNTs to disperse uniformly in matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Structural characteristics of UV‐irradiated polyurethane elastomers extended with α,ω‐alkane diols
Authors: Zia Khalid Mahmood , Zuber Mohammad , Barikani Mehdi , Bhatti Ijaz Ahmad , Sheikh Munir Ahmad
Published: May 2009

A series of polyurethane (PU) elastomers were prepared by the reaction of poly (ε‐caprolactone) (PCL) and 4, 4′‐diphenylmethane diisocyanate (MDI), extended with a series of chain extenders (CEs) having 2‐10 methylene units in their structure. The synthesized samples were irradiated for 50, 100, and 200 h as such the spectral distribution of the light is good match for terrestrial solar radiation. Fourier transform infrared (FTIR) spectroscopy was used to study the chemistry of monomers and final PU samples. The structural changes in the PU samples upon ultraviolet (UV) irradiation were characterized using FTIR spectroscopic technique. In comparison with non irradiated samples, there was a continuous decrease of the bands upon long‐term UV irradiation. The results revealed that final PU sample extended with 1,6‐hexane diol (1,6‐HDO) to 1, 10 decane diol (1,10‐DDO) have been fully degraded at 200 h irradiation. Comparing PU sample extended with 1, 6‐HDO and 1, 10‐DDO, it was found that the degradation rate of later is higher than former. It was concluded that CEs length has considerable effect on thermal degradation of PU and by increasing CEs length thermal degradation upon UV irradiation shifted to lower temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Accelerator adsorption onto carbon nanotubes surface affects the vulcanization process of styrene–butadiene rubber composites
Authors: De Falco A. , Marzocca A. J. , Corcuera M. A. , Eceiza A. , Mondragon I. , Rubiolo G. H. , Goyanes S.
Published: May 2009

The multiwalled carbon nanotubes (MWCNT) filled styrene–butadiene rubber (SBR) composites were prepared by incorporating MWCNT in a SBR/toluene solution and subsequently evaporating the solvent. These composites have shown a significant improvement in Young's modulus and tensile strength with respect to SBR gum without sacrificing high elongation at break. However, this improvement is less than expected at the higher filler content. Then, the influence of low concentrations of MWCNT on the vulcanization process of the SBR composites was studied by means of rheometer torque curves, swelling measurements, differential scanning calorimeter (DSC) analysis, and Fourier transform infrared (FTIR) spectroscopy. Also, their thermal degradation was studied by thermogravimetric analysis (TGA). It has been noticed that MWCNT affects the cure kinetics of SBR gum matrix reducing all parameters, i.e., the total heat rate and order of the reaction, scorch delay, maximum torque, and crosslink density. This effect increases as MWCNT content does, and it was attributed to the adsorption of the accelerator employed in the vulcanization (N‐tert‐butyl‐benzothiazole‐2‐sulfenamide) onto the MWCNT surface. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Simultaneous radiation grafting of vinylbenzyl chloride onto poly(tetrafluoroethylene‐co‐hexafluoropropylene) films
Authors: Shin Junhwa , Fei Geng , Kang Sung‐A , Ko Beom‐Seok , Kang Phil‐Hyun , Nho Young Chang
Published: May 2009

In this study, we demonstrated that vinylbenzyl chloride (VBC), a versatile monomer with reactive a chloromethyl group could be grafted onto a poly(tetrafluoroethylene‐co‐hexafluoropropylene) (FEP) film without a degradation of the chloromethyl group during a simultaneous irradiation process. The effects of various irradiation conditions such as the total dose, dose rate, solvent, and VBC concentration on the degree of grafting of VBC onto a FEP film were also investigated. The prepared PVBC‐grafted films were characterized using FTIR, TGA, and SEM EDX. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of surfactant properties on thermal behavior and sol–gel transitions in surfactant‐HPMC mixtures
Authors: Joshi Sunil C. , Chen Bin
Published: May 2009

Four surfactants, namely, sodium n‐decyl sulfate (SDeS), sodium n‐hexadecyl sulfate (SHS), sodium n‐dodecyl sulfate (SDS), and Triton X‐100, were used as additives to study thermal behavior and sol–gel transformations in dilute aqueous hydroxypropyl methyl cellulose (HPMC)/surfactant mixtures using micro‐differential scanning calorimetry. The influence of anionic surfactant, SDS on the gelation varied with SDS concentration where the sol–gel transition started at a higher temperature. Shape of the thermograms changed from single mode to dual mode at the SDS concentration of 6 mM and higher. SDeS and SHS, however, resulted in “salt‐in” effect of a different magnitude during gelation. Triton X‐100, being a non‐ionic surfactant, showed a minor “salt‐out” effect on the thermo‐gelation process. On the basis of different thermal behavior of anionic and non‐ionic surfactant/HPMC systems, a mechanism is proposed explaining how the chemical structure and electro‐charge of the surfactants affect the polymer/surfactant binding and polymer/polymer aggregation because of hydrophobic interaction during the sol–gel transition. © 2009 Wiley Periodicals, Inc. Journal of Applied Polymer Science, 2009
Effect of the addition of wood flours on the properties of rigid polyurethane foam
Authors: Yuan Jiang , Shi Sheldon Q.
Published: May 2009

The objective of this study is to investigate an appropriate process to fabricate the wood‐polyurethane hybrid composites [wood‐polyurethane foam (PUF)]. Rigid PUFs that contain up to 20% wood flours were successfully fabricated from polymeric 4,4‐diphenylmethane diisocyanate, polyols, silicone surfactant, dibutin dilaurate/dimethylethanolamine catalysts, and distilled water (chemical blowing agent). The effects of hydroxyl value of polyols, wood flour particle size, wood flour content, isocyanate index, and water amount on the compressive property of foam were investigated. The morphology of the cell was observed with a scanning electron microscope. Wood‐PUF with different densities were prepared at different water contents in the wood flours. The relationship between the compressive property and density was established following the Power law. The incorporation of wood flour improved the compressive property of PUF, whereas its tensile and flexural properties were reduced. The thermal stability of the PUF was improved with the addition of wood flour. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Biodegradation of montmorillonite filled oxo‐biodegradable polyethylene
Authors: Reddy Murali Mohan , Deighton Margaret , Bhattacharya Satinath , Parthasarathy Rajarathinam
Published: May 2009

Oxo‐biodegradation of polyethylene has been well studied with different pro‐oxidants and it has been shown that pro‐oxidants have limited role in the oxidation of polyethylene and do not have any role in microbial growth. However, in few recent studies, montmorillonite clay has been reported to promote the growth of microbes by keeping the pH of the environment at levels conducive to growth. In an attempt to improve the overall oxo‐biodegradation of polyethylene, montmorillonite nanoclay has been used in this study along with a pro‐oxidant. Film samples of oxo‐biodegradable polyethylene (OPE) and oxo‐biodegradable polyethylene nanocomposite (OPENac) were subjected to abiotic oxidation followed by microbial degradation using microorganism Pseudomonas aeruginosa. The progress of degradation was followed by monitoring the chemical changes of the samples using high‐temperature gel permeation chromatography (GPC) and infrared spectroscopy (FTIR). The growth of bacteria on the surface of the polymer was monitored using environmental scanning electron microscopy.

GPC data and FTIR results have shown that the abiotic oxidation of polyethylene is influenced significantly by the pro‐oxidant but not by nanoclay. But, the changes in molecular weight distribution and FTIR spectra for the biodegraded samples indicate that the growth rate of P. aeruginosa on OPENac is significantly greater than that on OPE. It indicates that nanoclay, by providing a favourable environment, helps in the growth of the microorganism and its utilisation of the polymer surface and the bulk of the polymer volume. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Poly(vinyl pyrrolidone‐co‐vinyl acetate)‐graft‐poly(ε‐caprolactone) as a compatibilizer for cellulose acetate/poly(ε‐caprolactone) blends
Authors: Higeshiro Tomokazu , Teramoto Yoshikuni , Nishio Yoshiyuki
Published: May 2009

Poly(vinyl pyrrolidone‐co‐vinyl acetate)‐graft‐poly(ε‐caprolactone) (PVPVAc‐g‐PCL) was synthesized by radical copolymerization of N‐vinyl‐2‐pyrrolidone (VP)/vinyl acetate (VAc) comonomer and PCL macromonomer containing a reactive 2‐hydroxyethyl methacrylate terminal. The graft copolymer was designed in order to improve the interfacial adhesiveness of an immiscible blend system composed of cellulose acetate/poly(ε‐caprolactone) (CA/PCL). Adequate selections of preparation conditions led to successful acquisition of a series of graft copolymer samples with different values of molecular weight (
$M_{n}^{{\rm PVPVA} {{\rm c} - g - {\rm PCL}}}$), number of grafts (n), and segmental molecular weight of PVPVAc between adjacent grafts (Mn (between grafts)). Differential scanning calorimetry measurements gave a still immiscible indication for all of the ternary blends of CA/PCL/PVPVAc‐g‐PCL (72 : 18 : 10 in weight) that were prepared by using any of the copolymer samples as a compatibilizer. However, the incorporation enabled the CA/PCL (4 : 1) blend to be easily melt‐molded to give a visually homogeneous film sheet. This compatibilizing effect was found to be drastically enhanced when PVPVAc‐g‐PCLs of higher $M_{ n}^{{\rm PVPVA}{\rm c} - g - {\rm PCL}}$
and Mn (between grafts) and lower n were employed. Scanning electron microscopy revealed that a uniform dispersion of the respective ingredients in the ternary blends was attainable with an assurance of the mixing scale of several hundreds of nanometers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Electrical characteristics of Al/polyindole Schottky barrier diodes. I. Temperature dependence
Authors: Altindal Seckin , Sari Bekir , Unal H. Ibrahim , Yavas Nihan
Published: May 2009

In this study, the forward and reverse bias current–voltage (I–V), capacitance–voltage (C–V), and conductance–voltage (G/ω–V) characteristics of Al/polyindole (Al/PIN) Schottky barrier diodes (SBDs) were studied over a wide temperature range of 140–400 K. Zero‐bias barrier height ΦB0(I–V), ideality factor (n), ac electrical conductivity (σac), and activation energy (Ea), determined by using thermionic emission (TE) theory, were shown fairly large temperature dispersion especially at lower temperatures due to surface states and series resistance of Al/PIN SBD. I–V characteristics of the Al/PIN SBDs showed an almost rectification behavior, but the reverse bias saturation current (I0) and n were observed to be high. This high value of n has been attributed to the particular distribution of barrier heights due to barrier height inhomogeneities and interface states that present at the Al/PIN interface. The conductivity data obtained from G/ωV measurements over a wide temperature range were fitted to the Arrhenius and Mott equations and observed linear behaviors for σac vs. 1/T and ln σac vs. 1/T1/4 graphs, respectively. The Mott parameters of T0 and K0 values were determined from the slope and intercept of the straight line as 3.8 × 107 and 1.08 × 107 Scm−1K1/2, respectively. Assuming a value of 6 × 1012 s−1 for ν0, the decay length α−1 and the density states at the Fermi energy level, N(EF) are estimated to be 8.74 Å and 1.27 × 1020 eV−1cm−3, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
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

The 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

The 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

Poly(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

This 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

Poly(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

In 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

Select 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.

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Some 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

This 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

In 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

N‐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

This 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

Green 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.

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An 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

Electrocatalytic 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

The 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

n‐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

The 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

An 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

The 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

PEGylation 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.
Experimental Study on the Molecular Dimension and Configuration of Polymer and Its Flow Characteristics from Electrolyte Effect
Authors: LU Xiangguo , WANG Xiaoyan , JIANG Weidong
Published: May 2009

Molecular clew dimension and configuration of polymer, and flow characteristics of polymer solution were studied from electrolyte effect, by making use of dynamic light scattering (DLS), scanning electron microscopy (SEM), apparent viscosity method and core flow experiment. It can be observed that with the electrolyte concentration increasing, there exists a variation trend of "decreasing, increasing and decreasing again" to the molecular clew dimension of the polymer. The compression action of Ca2+or Mg2+to the double electrode layer of polymer molecules is more powerful by comparison against Na+, which results in that Ca2+and Mg2+have a more extensive effect on the viscosity of polymer solution, and clew dimensions and their distribution. With the electrolyte concentration increasing, the polymer molecular configuration of multi‐layer stereoscopic random reticulation transformed into a dendritic one. During the succeeding water flooding, the variation degree of injection pressure of core was mainly determined by the swelling extent of molecular clew of retained polymer and the produced amount of polymer. And the bigger the molecular weight of polymer is, the stronger the compression or swelling action of electrolyte to the molecule clews is, and the greater the increasing degree of injection pressure during succeeding water flooding is. The greater difference of electrolyte concentrations in used water between polymer flooding and succeeding water flooding can result in greater increasing degree of injection pressure during the succeeding water flooding. So, an advisable increasing in difference of electrolyte concentrations in used water between the polymer flooding and succeeding water flooding was proposed when designing the polymer flooding performance in oilfields, which has promising result for improving effect of polymer flooding.
Synthesis of Soluble Fluorene‐polyimino Ketone
Authors: LUO Xuan , CHANG Guanjun , WANG Qingfu , JIAO Wenxiu , ZHANG Lin , LIN Runxiong
Published: May 2009

Based on the 9,9‐di(4‐anilinyl)fluorene, structurally different fluorene‐polyimino ketones have been obtained by the Buchwald‐Hartwig cross coupling reaction. Their structure and performance have been characterized by FT‐IR, 1H NMR, UV‐vis and thermal analysis. The results show an agreement with the proposed structure, which possesses high glass transition temperature (Tg>250 °C) and good thermal stability with high decomposition temperatures in nitrogen atmosphere (TD>520 °C). Additionally, the polymers synthesized showed good solubility, which can be dissolved in common organic solvent CHCl3 at room temperature.
A spectrally efficient frequency diversity technique for single‐carrier modulations with frequency division multiplexing
Authors: Araújo Teresa , Dinis Rui
Published: May 2009

When the number of relevant propagation paths between the transmitter and the receiver is small and/or when they are not separable (i.e. the difference between the corresponding delays is smaller than the symbol duration), we can have deep fading effects and poor performance, especially for slow‐varying channels. In this case, the use of diversity techniques is strongly recommendable.

In this paper, we consider an single‐carrier‐based (SC) block transmission, employing frequency domain equalisation (FDE) receivers and we present a frequency diversity technique that allows high spectral efficiencies. As with conventional frequency diversity techniques,Lreplicas of a given signal are transmitted atLdifferent frequencies. However, contrarily to conventional frequency diversity schemes, up toLusers can share this set ofLfrequency bands. Since this leads to strong interference levels, we propose an iterative, frequency‐domain receiver where all the users sharing theLfrequencies are jointly detected.

Our performance results show that the proposed frequency diversity scheme allows high diversity gains, while keeping the spectral efficiency of conventional SC schemes. Moreover, we can cope with channels that can be severely time‐dispersive and/or can have deep fading effects. Copyright © 2009 John Wiley & Sons, Ltd.
Genomic and clinical analyses of 2p24 and 12q13‐q14 amplification in alveolar rhabdomyosarcoma: A report from the Children's Oncology Group
Authors: Barr Frederic G. , Duan Fenghai , Smith Lynette M. , Gustafson Donna , Pitts Mandy , Hammond Sue , Gastier‐Foster Julie M.
Published: May 2009

Alveolar rhabdomyosarcoma (ARMS) is an aggressive pediatric cancer that is related to the skeletal muscle lineage and characterized by recurrent chromosomal translocations. Within the ARMS category, there is clinical and genetic heterogeneity, consistent with the premise that “primary” genetic events collaborate with “secondary” events to give rise to subsets with varying clinical features. Previous studies demonstrated that genomic amplification occurs frequently in ARMS. In the current study, we used oligonucleotide arrays to localize two common amplicons to the 2p24 and 12q13‐q14 chromosomal regions. Based on the copy number array data, we sublocalized the minimum common regions of 2p24 and 12q13‐q14 amplification to a 0.83 Mb region containing the DDX1 and MYCN genes, and a 0.55 Mb region containing 27 genes, respectively. Using fluorescent in situ hybridization assays to measure copy number of the 2p24 and 12q13‐q14 regions in over 100 cases, we detected these amplicons in 13% and 12% of cases, respectively. Comparison with fusion status revealed that 2p24 amplification occurred preferentially in cases positive for PAX3‐FOXO1 or PAX7‐FOXO1 while 12q13‐q14 amplification occurred preferentially in PAX3‐FOXO1‐positive cases. Expression studies demonstrated that MYCN was usually overexpressed in cases with 2p24 amplification while multiple genes were overexpressed in cases with 12q13‐q14 amplification. Finally, although 2p24 amplification did not have a significant association with clinical outcome, 12q13‐q14 amplification was associated with significantly worse failure‐free and overall survival that was independent of gene fusion status. © 2009 Wiley‐Liss, Inc.
Human immunodeficiency virus and hepatitis C infections induce distinct immunologic imprints in peripheral mononuclear cells # †
Authors: Kottilil Shyam , Yan Michael Y. , Reitano Kristin N. , Zhang Xiaozhen , Lempicki Richard , Roby Gregg , Daucher Marybeth , Yang Jun , Cortez Karoll J. , Ghany Marc , Polis Michael A. , Fauci Anthony S.
Published: May 2009

Coinfection with hepatitis C virus (HCV) is present in one-third of all human immunodeficiency virus (HIV)-infected individuals in the United States and is associated with rapid progression of liver fibrosis and poor response to pegylated interferon (IFN) and ribavirin. In this study we examined gene expression profiles in peripheral blood mononuclear cells (PBMCs) from different groups of individuals who are monoinfected or coinfected with HIV and HCV. Data showed that HIV and HCV viremia up-regulate genes associated with immune activation and immunoregulatory pathways. HCV viremia is also associated with abnormalities in all peripheral immune cells, suggesting a global effect of HCV on the immune system. Interferon-α-induced genes were expressed at a higher level in PBMCs from HIV-infected individuals. HCV and HIV infections leave distinct profiles or gene expression of immune activation in PBMCs. HIV viremia induces an immune activated state; by comparison, HCV infection induces immunoregulatory and proinflammatory pathways that may contribute to progression of liver fibrosis. Conclusion: An aberrant type-I IFN response seen exclusively in HIV-infected individuals could be responsible for the poor therapeutic response experienced by HIV/HCV coinfected individuals receiving interferon-α-based current standard of care. (Hepatology 2009;50:34–45.)
Aggravation by prostaglandin E2 of interleukin-6-dependent insulin resistance in hepatocytes #
Authors: Henkel Janin , Neuschäfer-Rube Frank , Pathe-Neuschäfer-Rube Andrea , Püschel Gerhard P.
Published: May 2009

Hepatic insulin resistance is a major contributor to fasting hyperglycemia in patients with metabolic syndrome and type 2 diabetes. Circumstantial evidence suggests that cyclooxygenase products in addition to cytokines might contribute to insulin resistance. However, direct evidence for a role of prostaglandins in the development of hepatic insulin resistance is lacking. Therefore, the impact of prostaglandin E2 (PGE2) alone and in combination with interleukin-6 (IL-6) on insulin signaling was studied in primary hepatocyte cultures. Rat hepatocytes were incubated with IL-6 and/or PGE2 and subsequently with insulin. Glycogen synthesis was monitored by radiochemical analysis; the activation state of proteins of the insulin receptor signal chain was analyzed by western blot with phosphospecific antibodies. In hepatocytes, insulin-stimulated glycogen synthesis and insulin-dependent phosphorylation of Akt-kinase were attenuated synergistically by prior incubation with IL-6 and/or PGE2 while insulin receptor autophosphorylation was barely affected. IL-6 but not PGE2 induced suppressors of cytokine signaling (SOCS3). PGE2 but not IL-6 activated extracellular signal-regulated kinase 1/2 (ERK1/2) persistently. Inhibition of ERK1/2 activation by PD98059 abolished the PGE2-dependent but not the IL-6-dependent attenuation of insulin signaling. In HepG2 cells expressing a recombinant EP3-receptor, PGE2 pre-incubation activated ERK1/2, caused a serine phosphorylation of insulin receptor substrate 1 (IRS1), and reduced the insulin-dependent Akt-phosphorylation. Conclusion: PGE2 might contribute to hepatic insulin resistance via an EP3-receptor-dependent ERK1/2 activation resulting in a serine phosphorylation of insulin receptor substrate, thereby preventing an insulin-dependent activation of Akt and glycogen synthesis. Since different molecular mechanisms appear to be employed, PGE2 may synergize with IL-6, which interrupted the insulin receptor signal chain, principally by an induction of SOCS, namely SOCS3. (Hepatology 2009.)