bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlation of chemical shrinkage of polyacrylonitrile fibres with kinetics of cyclization
Authors: Simitzis Johannis , Soulis Spyridon 
Published: June 2007

AbstractIt has been established that the most important step in the production of carbon fibres from polyacrylonitrile (PAN) precursor fibres is the oxidative thermal treatment applied. During this treatment, physical phenomena and chemical reactions take place accompanied by the shrinkage of the fibres, which has a physical or chemical origin, depending on the nitrile cyclization reactions. The aim of the present study is to establish a correlation between the chemical shrinkage of PAN fibres and the kinetics of cyclization reactions. Based on the isothermal treatment of PAN fibres, we developed a method in order to distinguish between physical and chemical shrinkages. The onset time for the chemical shrinkage follows a relationship with temperature. Chemical shrinkage versus cyclization time data were fitted with the exponential rise to the maximum of the curves. Furthermore, the cyclization kinetics was studied using differential scanning calorimetry and the kinetic parameters determined were identical to those calculated from the chemical shrinkage, demonstrating that the latter is directly related to the kinetics of the cyclization reactions. It was therefore concluded that according to the method developed to distinguish the physical from the chemical shrinkages: (1) there exists a certain onset time for a given treatment temperature to trigger the chemical shrinkage; (2) cyclization reactions do not start below a limiting temperature of 168 °C; (3) at 340 °C, the temperature where the cyclization reactions are completed, the maximum shrinkage is 24%; and (4) the oxidized PAN fibres contain mainly ladder polymer structures with approximately symmetrical sequences connected in angled positions. Copyright © 2007 Society of Chemical Industry
An improved method of sample preparation on AnchorChip™ targets for MALDI‐MS and MS/MS and its application in the liver proteome project
Authors: Zhang Xumin , Shi Liang , Shu Shaokung , Wang Yuan , Zhao Kang , Xu Ningzhi , Liu Siqi , Roepstorff Peter 
Published: June 2007

AbstractAn improved method for sample preparation for MALDI‐MS and MS/MS using AnchorChip™ targets is presented. The method, termed the SMW method (sample, matrix wash), results in better sensitivity for peptide mass fingerprinting as well as for sequencing by MS/MS than previously published methods. The method allows up‐concentration and desalting directly on the mass spectrometric target and should be amenable for automation. A draw back caused by extensive oxidation of methionine and tryptophan in the SMW method can be alleviated by the addition of n‐octyl glucopyranoside and DTT to the sample solution. The method was validated for protein identification from a 2‐DE based liver proteome study. The SMW method resulted in identification of many more proteins and in most cases with a better score than the previously published methods.
Proteomic analysis of core breakdown disorder in Conference pears (Pyrus communisL.)
Authors: Pedreschi Romina , Vanstreels Els , Carpentier Sebastien , Hertog Maarten , Lammertyn Jeroen , Robben Johan , Noben Jean‐Paul , Swennen Rony , Vanderleyden Jozef , Nicolaï Bart M. 
Published: June 2007

Abstract2‐DE was applied to study core breakdown disorder in controlled atmosphere stored ’︁Conference' pears. This physiological disorder is characterized by internal browning of the fruit tissue and the development of cavities. Suitable protein phenol extraction/ammonium acetate‐methanol precipitation and 2‐DE protocols for a wide pH range were established for pear tissue. The protein expression profiles of healthy, sound (intact tissue of pears with core breakdown) and brown tissue were analyzed with the univariate non‐parametric Kolmogorov‐Smirnov test and multivariate statistical techniques such as principal component analysis and partial least square discriminant analysis. Both statistical approaches revealed interesting differentially expressed proteins between healthy and disordered pears. LC‐ESI‐MS/MS identification of differentially expressed proteins between healthy and sound tissue revealed their participation in the energy metabolism, the antioxidant system and ethylene biosynthesis. Up‐regulated characteristic proteins in brown tissue were mainly involved in energy metabolism and defense mechanisms. Proteomics coupled to univariate and multivariate statistical techniques seems to be an efficient approach to get a better insight into the different mechanisms and pathways leading to the core breakdown disorder.
Efficient on‐chip proteolysis system based on functionalized magnetic silica microspheres
Authors: Li Yan , Yan Bo , Deng Chunhui , Yu Wenjia , Xu Xiuqing , Yang Pengyuan , Zhang Xiangmin 
Published: June 2007

AbstractAn easily replaceable enzymatic microreactor has been fabricated based on the glass microchip with trypsin‐immobilized magnetic silica microspheres (MS microspheres). Magnetic microspheres with small size (∼300 nm in diameter) and high magnetic responsivity to magnetic field (68.2 emu/g) were synthesized and modified with tetraethyl orthosilicate (TEOS). Aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA) were then introduced to functionalize the MS microspheres for enzyme immobilization. Trypsin was stably immobilized onto the MS microspheres through the reaction of primary amines of the proteins with aldehyde groups on the MS microspheres. The trypsin‐immobilized MS microspheres were then locally packed into the microchannel by the application of a strong field magnet to form an on‐chip enzymatic microreactor. The digestion efficiency and reproducibility of the microreactor were demonstrated by using cytochrome c (Cyt‐C) as a model protein. When compared with an incubation time of 12 h by free trypsin in the conventional digestion approach, proteins can be digested by the on‐chip microreactor in several minutes. This microreactor was also successfully applied to the analysis of an RPLC fraction of the rat liver extract. This opens a route for its further application in top‐down proteomic analysis.
Characterization of proteomic changes in cardiac mitochondria in streptozotocin‐diabetic rats using iTRAQ™ isobaric tags
Authors: Jüllig Mia , Hickey Anthony J. , Middleditch Martin J. , Crossman David J. , Lee Stanley C. , Cooper Garth J. S. 
Published: June 2007

AbstractDiabetes now affects more than 5% of the world's population and heart failure is the most common cause of death amongst diabetic patients. Accumulating evidence supports a view that myocardial mitochondrial structural and functional changes are central to the onset of diabetic heart failure, but the exact nature of these changes at the proteomic level remains unclear.Here we report on proteomic changes in diabetic rat heart mitochondria following 120 days of streptozotocin‐diabetes using the recently developed iTRAQ™ labeling method, which permits quantification of proteins directly from complex mixtures, bypassing the limitations associated with gel‐based methods such as 2‐DE. Of 252 unique proteins identified, 144 were represented in at least three of six individual paired experiments. Relative amounts of 65 proteins differed significantly between the groups, confirming that the cardiac mitochondrial proteome is indeed impacted by diabetes. The most significant changes were increased protein levels of enzymes involved in mitochondrial oxidation of long‐chain fatty acids, which was also confirmed by enzyme assays, and decreased levels of multiple enzymes involved in oxidative phosphorylation and catabolism of short‐chain fatty acids and branched‐chain amino acids. We also found significant changes in levels of several enzymes linked to oxidative stress.
Recent Advances in the Chemistry of N5+, N5− and High‐Oxygen Compounds
Authors: Christe Karl O. 
Published: June 2007

AbstractAn overview of our work in the areas of polynitrogen and high‐nitrogen and high‐oxygen chemistry is given. Areas of interest include the synthesis and characterization of novel polynitrogen ions, such as N5+ and N5−. Efforts are discussed to combine the N5+ cation with energetic counter‐ions, such as N3−, NO3−, ClO4−, B(N3)4− and P(N3)6−. In the area of high‐oxygen carriers, complex nitrato anions were successfully combined with tetrazolium cations to yield CO/H2O balanced ionic liquids of interest for liquid monopropellants.
An Advanced GAP/AN/TAGN Propellant. Part II: Stability and Storage Life
Authors: Judge Michael D. , Badeen Christopher M. , Jones David E. G. 
Published: June 2007

AbstractA solid rocket propellant based on glycidyl azide polymer (GAP) binder plasticized with nitrate esters and oxidized with a mixture of ammonium nitrate (AN) and triaminoguanidine nitrate (TAGN) and including non‐lead ballistic modifiers, was formulated. The propellant was designed so as to produce non‐acidic and non‐toxic exhaust products while still providing reasonably good burning rate and impulse. This propellant was characterized with respect to thermal and chemical stability and storage life by a variety of test methods. The data indicate that the propellant exhibits good stability and is suitably safe for prolonged storage. Characterization data for this propellant with regard to processing parameters, tensile properties, and ballistic performance are presented in a companion paper.
A Flow Time Model for Melt‐Cast Insensitive Explosive Process
Authors: Guillemin Jean‐Philippe , Brunet Luc , Bonnefoy Olivier , Thomas Gérard 
Published: June 2007

AbstractDiphasic flows of concentrated suspensions of melt‐cast insensitive explosives exhibit specific rheological properties. In order to limit the handling of pyrotechnical products presenting a risk with respect to the mechanical and thermal shocks, a lot of work has been undertaken for many years in the civil engineering sector. The objective of this study is to propose a predictive model of the flow time of a concentrated suspension through a nozzle located at the bottom of a tank. Similar to our industrial process, the suspension is made out of insensitive energetic materials and flows under gravity. Experimental results are compared to three models (Quemada, Krieger‐Dougherty, and Mooney) predicting the viscosity μ of a suspension as a function of the solid volume fraction ϕ, the maximum packing density ϕm and the viscosity μ0 of the interstitial liquid. De Larrard's model is used to calculate ϕm. The value of viscosity measured for the pure liquid is close to the one predicted by the Bernoulli theorem, where liquids are considered as incompressible and inviscid. Finally, it was found that the Quemada's model gives a fair agreement between predictions and experiments.
The impact of birth weight on prostate cancer incidence and mortality in a population‐based study of men born in 1913 and followed up from 50 to 85 years of age
Authors: Eriksson Margaretha , Wedel Hans , Wallander Mari‐Ann , Krakau Ingvar , Hugosson Jonas , Carlsson Sture , Svärdsudd Kurt 
Published: June 2007

AbstractBACKGROUNDInsulin‐like growth factor‐I (IGF‐I) hormone is directly associated with birth weight (BW), and high IGF‐I measured in adults is associated with increased risk of prostate cancer (PCA). Whether BW and PCA are related is inconclusive to date.METHODSBW and PCA incidence and mortality data for a population‐based cohort of 1,436 singleton Swedish men born in 1913 and followed until 85 years of age were obtained.RESULTSBW ≥ 4,250 g was associated with significantly higher PCA incidence [62% (CI: 4%–151%)] and PCA mortality [82% (CI: 3%–221%)] than BW 3,001–4,249 g, even when other potential effect modifiers were taken into account. The hazards ratio for PCA incidence fell from approximately 3 at age 50 to unity at age 85. Approximately one out of every six PCA incident cases between 50 and 70 years of age could be attributed to BW ≥ 4,250 g.CONCLUSIONSIn the current study PCA incidence and mortality rate appears to increase with BW. Prostate 67: 1247–1254, 2007. © 2007 Wiley‐Liss, Inc.
Propanil and swep inhibit 4‐coumarate:CoA ligase activity in vitro
Authors: Yun Min‐Soo , Chen Weijun , Deng Fan , Yogo Yasuhiro 
Published: June 2007

Abstract4‐Coumarate:CoA ligase (4CL, EC 6.2.1.12) in the phenylpropanoid pathway in plants has attracted interest as a novel target for developing effective plant growth inhibitors (PGIs). In a previous study in which the 4CL inhibitory activity of 28 existing herbicides was investigated using an optimized in vitro screening assay, 4CL activity was found to be strongly inhibited by propanil and swep at 100 µM. Here, further experimental evidence is provided to substantiate the previous result. Using 4‐coumaric acid as substrate, tobacco 4CL activity was inhibited by propanil or swep in a concentration‐dependent manner, with 50% inhibition concentrations (I50) of 39.6 and 6 µM respectively. These herbicides also exhibited uncompetitive inhibition towards 4‐coumaric acid. Furthermore, 4CLs from several plant species were inhibited by the herbicides within a range from 1 to 50 µM. It is proposed that these herbicides have another site of action as a result of the inhibition of 4CL in the phenylpropanoid pathway, and this enzyme represents a new target site for the development of PGI. Copyright © 2007 Society of Chemical Industry
Efficient three‐wave mixing via intersubband transitions in a semiconductor quantum well
Authors: Li Jiahua 
Published: June 2007

AbstractWe put forward an efficient three‐wave mixing (TWM) scheme in an asymmetric semiconductor quantum well (SQW) based on intersubband transitions. Using the coupled Schrödinger–Maxwell approach, we derive the corresponding explicit analytical expressions for the input probe and generated TWM signal fields. Such a nonlinear optical process may be used for efficiently generating coherent short‐wavelength radiation in the SQW solid‐state system, which is much more practical than that in atomic system because of its flexible design and the controllable interference strength. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low‐refractive‐index materials: A new class of optical thin‐film materials
Authors: Schubert E. F. , Kim J. K. , Xi J.‐Q. 
Published: June 2007

AbstractThe refractive index, a most fundamental quantity in optics and optoelectronics, determines many figures of merit of optical components such as reflectors, filters, and resonators. Here we present a new class of optical thin‐film materials that have a very low refractive index. Specular films of high optical quality with refractive indices as low as 1.05 are demonstrated. A single pair DBR incorporating low‐n material is demonstrated to have enhanced reflectivity, showing the great potential of low‐refractive‐index films for many photonic device applications. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Direct synthesis of II–VI compound nanocrystals in polymer matrix
Authors: Antolini F. , Di Luccio T. , Laera A. M. , Mirenghi L. , Piscopiello E. , Re M. , Tapfer L. 
Published: June 2007

AbstractThe production of II–VI semiconductor compound – polymer matrix nanocomposites by a direct in‐situ thermolysis process is described. Metal‐thiolate precursor molecules embedded in a polymer matrix decompose by a thermal annealing and the nucleation of semiconductor nanocrystals occurs. It is shown that the nucleation of nanoparticles and the formation of the nanocomposite can be also achieved by laser beam irradiation; this opens the way towards a “lithographic” in‐situ nanocomposite production process. A possible growth and nanocomposite formation mechanism, describing the structural and chemical transformation of the precursor molecules, their decomposition and the formation of the nanoparticles, is presented. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrostatic electron piston pump with in‐plane gate transistors
Authors: Draghici M. , Salloch D. , Melnikov A. , Wieck A. D. 
Published: June 2007

AbstractWe have demonstrated an electron pump with in‐plane gate (IPG) transistors fabricated by focused ion beam (FIB) implantation on GaAs–Alx Ga1–x As modulation‐doped heterostructure with a two‐dimensional electron gas (2DEG). The maskless fabrication process does not require any alignment between the circuit elements including the sources, the drains and the gates of the IPG transistors. Although, the device is operating at low frequencies (tens of kHz), it is capable to produce a current more than one order of magnitude higher than other electron pumps based on Coulomb blockade and single electron tunneling effects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Progress in the growth of nonpolar gallium nitride
Authors: Haskell B. A. , Nakamura S. , DenBaars S. P. , Speck J. S. 
Published: June 2007

AbstractThe active regions of conventional c ‐plane (Al,In,Ga)N optoelectronic devices suffer from deleterious polarization effects. These polarization effects can be eliminated by growing devices on alternative GaN planes, such as {1$ \bar 1 $00} m ‐plane or {11$ \bar 2 $0} a ‐plane films. Previous attempts to grow nonpolar GaN by vapor phase and molecular beam epitaxy methods yielded rough and faceted surfaces that were unsuitable for device use. Beginning with Waltereit et al.'s work [Nature 406, 865 (2000)], significant progress has been made in improving nonpolar GaN structural quality and morphology. This paper reviews the structural and morphological characteristics of planar, nonpolar a ‐plane and m ‐plane GaN films grown by vapor phase and molecular beam epitaxy techniques. Defect reduction via lateral epitaxial overgrowth, and the influence of extended defects on surface morphology will be further discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Confidence intervals for the comparison of variability estimates for a mixed model
Authors: Daniels Lorraine , Borror Connie M. , Burdick Richard K. 
Published: June 2007

AbstractIn this paper, we develop methods for generating confidence intervals for the comparison of variability estimates in a mixed‐effects model. A generalized confidence interval (GCI) is developed and contrasted to the modified large sample (MLS) method with an adjustment for a fixed effect. The methods are assessed using a computer simulation. Recommendations are provided for selecting an appropriate method. Copyright © 2007 John Wiley & Sons, Ltd.
Monitoring autocorrelated processes using variable sampling schemes at fixed‐times
Authors: Zou Changliang , Wang Zhaojun , Tsung Fugee 
Published: June 2007

AbstractTraditional control charts for process monitoring are based on taking samples of fixed size from the process using a fixed sampling interval. A recent development in control charts is the use of adaptive control charts, i.e. the variable sampling interval (VSI) and variable sampling size charts. This paper extends this idea to the autocorrelated process. We consider a time series model which is a first‐order autoregressive process plus a random error. With variable intervals, the sampling time may be inconvenient, so using only two intervals, referred to as ‘variable sampling interval at fix times’ makes the method easier to use in practice. The sampling rate can also be adjusted by the number of samples collected, VSRFT, for ‘variable sampling rate at fixed times’. We
study what we call ‘variable sampling at fixed times’, VSFT, which includes both VSIFT and VSRFT schemes, using a Markov chain model and integral equations. We show that our methods detect process shifts faster, on average, than fixed sampling X‐bar charts, and at least comparable detection ability with the less practical VSI charts. Copyright © 2007 John Wiley & Sons, Ltd.
Flavonoid profile in soybeans by high‐performance liquid chromatography/tandem mass spectrometry
Authors: Cavaliere Chiara , Cucci Francesca , Foglia Patrizia , Guarino Chiara , Samperi Roberto , Laganà Aldo 
Published: June 2007

AbstractFlavonoid profiling of a soybean sample has been performed by liquid chromatography/positive electrospray tandem mass spectrometry (LC/ESI+‐MS/MS) using a quadrupole‐linear ion trap (QLIT) instrument with an information‐dependent data acquisition (IDA) protocol that looped, in a single run, an enhanced MS scan and an enhanced product ion scan. As compromise between time and obtainable information, spectra acquisition was split into two distinct runs: 220–450 Th and 400–800 Th, respectively. The isoflavones daidzein and genistein were identified as aglycones, monoglycosides, diglycosides, triglycosides, acetylglycosides, malonylglycosides, malonyl diglycosides, and dimalonyl diglycosides, whereas glycitein triglycosides, acetylglycosides, and dimalonyl diglycosides were not detected. Also kaempferol di‐ and triglycosides, malonylglycosides and malonyl diglycosides, previously reported in soy leaves and pods, and four naringenin malonylglycosides were identified. Copyright © 2007 John Wiley & Sons, Ltd.
Identification of oxidative post‐translational modification of serum albumin in patients with idiopathic pulmonary arterial hypertension and pulmonary hypertension of sickle cell anemia
Authors: Odhiambo Adam , Perlman David H. , Huang Hua , Costello Catherine E. , Farber Harrison W. , Steinberg Martin H. , McComb Mark E. , Klings Elizabeth S. 
Published: June 2007

AbstractPulmonary hypertension (PH) in sickle cell anemia (SCA) is characterized by decreased nitric oxide bioavailability that might, in part, be related to oxidative stress. Oxidative post‐translational modifications of plasma proteins may serve as hallmarks of disease severity and could result in altered protein function and structure. We hypothesized that serum albumin in patients with PH of SCA undergoes oxidative post‐translational modification and that this modification may reflect important mediators of disease pathogenesis that are common to both idiopathic pulmonary arterial hypertension (IPAH) and PH of SCA. To explore this hypothesis, we studied albumin purified from the plasma of patients in four subject groups: SCA and PH, SCA steady‐state without PH, IPAH, and normal volunteers. Purified albumin was analyzed by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). Using MALDI‐TOFMS, we identified that an ion corresponding to a malondialdehyde (MDA)‐modified albumin peptide was differentially present in patients with IPAH and PH of SCA. These results were confirmed by dot‐blotting and Western analysis. We localized the site of MDA modification to albumin residue K159 using LC/MS/MS. Thus, we have identified an MDA modification of serum albumin that appears to be a common link between PH of SCA and IPAH. This finding supports the notion that oxidative stress modulates the pathogenesis of PH of SCA and suggests that this and other post‐translational modifications may be important biomarkers of disease. Copyright © 2007 John Wiley & Sons, Ltd.