bluuebunny/crossref_metadata_2025_split huggingface dataset:
A kinetic study of the gas‐phase reactions of OIO with NO, NO2, and Cl2
Authors: Enami Shinichi , Hoshino Yosuke , Kawasaki Masahiro 
Published: October 2007

AbstractThe kinetics of iodine dioxide (OIO) reactions with nitric oxide (NO), nitrogen dioxide (NO2), and molecular chlorine (Cl2) are studied in the gas‐phase by cavity ring‐down spectroscopy. The absorption spectrum of OIO is monitored after the laser photodissociation, 266 or 355 nm, of the gaseous mixture, CH2I2/O2/N2, which generates OIO through a series of reactions. The second‐order rate constant of the reaction OIO + NO is determined to be (4.8 ± 0.9) × 10−12 cm3 molecule−1 s−1 under 30 Torr of N2 diluent at 298 K. We have also measured upper limits for the second‐order rate constants of OIO with NO2 and Cl2 to be k < 6 × 10−14 cm3 molecule−1 s−1 and k < 8 × 10−13 cm3 molecule−1 s−1, respectively. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 688–693, 2007
Synthesis and Characterization of Hyperbranched Polymers from the Polymerization of Glycidyl Methacrylate and Styrene Using Cp2TiCl as a Catalyst
Authors: Kong Li‐zhi , Pan Cai‐yuan 
Published: October 2007

AbstractHyperbranched poly(glycidyl methacrylate) (PGMA) and poly(GMA‐co‐styrene) have been synthesized by the self‐condensing vinyl polymerization of GMA and the copolymerization of GMA and St. Cp2Ti(III)Cl catalyzed the epoxy groups to produce initiating radicals and Cu(II)X2 (X = Br or Cl) was used for control of the polymerization. The resultant polymers were characterized by GPC and 1H NMR, and the molecular weights, the molecular weight distribution and the degree of branching were determined. The branching structure of the polymers was further confirmed by a hydrolysis test. Hyperbranched star polymers with HPGMA as the core and PSt as the arms were synthesized by the atom transfer radical polymerization of St using HPGMA as a macroinitiator. The resultant products were analyzed by GPC and 1H NMR. Their morphology in solution was investigated by TEM. The hyperbranched polymers were modified by various acids and amines, and the variation in solution properties was investigated.magnified image
Polymorphism Control of Poly(vinylidene fluoride) through Electrospinning
Authors: Zheng Jianfen , He Aihua , Li Junxing , Han Charles C. 
Published: October 2007

AbstractPolymorphism control of PVDF has been realized through electrospinning. PVDF fibrous membranes with fiber diameter in the range of 100 nm to several micrometers were produced by electrospinning and the crystal phase of electrospun PVDF fibers can be adjusted at the same time. Through the control of electrospinning parameters such as the solvent, electrospinning temperature, feeding rate, and tip‐to‐collector distance, PVDF fibrous membranes containing mainly α‐ or β‐ or γ‐phase could be fabricated successfully.magnified image
QQ‐HSQC: a quick, quantitative heteronuclear correlation experiment for NMR spectroscopy
Authors: Peterson Daniel J. , Loening Nikolaus M. 
Published: October 2007

AbstractQuantitative heteronuclear single quantum coherence (Q‐HSQC) is a variant of the HSQC experiment that provides quantitative peak areas. This is accomplished by combining signals acquired using four different INEPT delays. Consequently, the experiment requires four times as many scans as the HSQC experiment to achieve the same resolution in the indirect dimension. We have removed this drawback by modifying the Q‐HSQC experiment so that signals corresponding to different INEPT delays are acquired simultaneously from different parts of the sample. This new experiment, which we call Quick, Quantitative HSQC (QQ‐HSQC), has the quantitative properties of the Q‐HSQC experiment but only requires as many scans as a conventional HSQC experiment. Copyright © 2007 John Wiley & Sons, Ltd.
The impact of the π‐electron conjugation on 15N, 13C and 1H NMR chemical shifts in push–pull benzothiazolium salts. Experimental and theoretical study
Authors: Hrobárik Peter , Horváth Branislav , Sigmundová Ivica , Zahradník Pavol , Malkina Olga L. 
Published: October 2007

AbstractThe 15N as well as 13C and 1H chemical shifts of eight push–pull benzothiazolium iodides with various π‐conjugated chains between dimethylamino group and benzothiazolium moiety have been determined by NMR spectroscopy at the natural‐abundance level of all nuclei in DMSO‐d6 solution. In general, the quaternary benzothiazolium nitrogen is more shielded [δ(15N‐3) vary between − 241.3 and − 201.9 ppm] with respect to parent 3‐methylbenzothiazolium iodide [δ(15N‐3) = − 183.8 ppm], depending on the length and constitution of the π‐conjugated bridge. A larger variation in 15N chemical shifts is observed on dimethylamino nitrogen, which covers the range of − 323.3 to − 257.2 ppm. The effect of π‐conjugation degree has a less pronounced influence on 13C and 1H chemical shifts.Experimental data are interpreted by means of density functional theory (DFT) calculations. Reasonable agreement between theoretical and experimental 15N NMR chemical shifts was found, particularly when performing calculations with hybrid exchange‐correlation functionals. A better accord with experiment is achieved by utilizing a polarizable continuum model (PCM) along with an explicit treatment of hydrogen‐bonding between the solute and the water present in dimethylsulfoxide (DMSO). Finally, 13C and 1H NMR spectra were computed and analysed in order to compare them with available experimental data. Copyright © 2007 John Wiley & Sons, Ltd.
The role of aromatic groups in the Tobey–Simon additivity rule for vinylic protons
Authors: Shine Henry J. , Rangappa Paramashivappa 
Published: October 2007

AbstractThe Tobey–Simon (additivity) rule for aromatic groups which was devised about 40 years ago has been found to need revision. The rule shows an aromatic group attached to a CC double bond as causing a downfield chemical shift of a cis‐related vinylic proton and a small upfield shift of a trans‐related proton. A search of data in the recent literature has shown that this rule should apply mainly to monosubstituted phenyl groups and some polynuclear aromatics. In contrast with them, 2,6‐disubstituted phenyl, 2,4,6‐trisubstituted phenyl and 9‐anthracenyl groups cause cis‐related vinylic protons to resonate upfield of comparable trans‐related protons. Further, the current rule for o‐substituted phenyl groups has been found to be inaccurate. In writing a rule for aromatic groups, therefore, greater attention needs to be given to the diversity of effects that these groups have on chemical shifts of vinylic protons. Copyright © 2007 John Wiley & Sons, Ltd.
Spermatogenic cell‐specific type 1 hexokinase is the predominant hexokinase in sperm
Authors: Nakamura Noriko , Shibata Haruna , O'Brien Deborah A. , Mori Chisato , Eddy Edward M. 
Published: October 2007

AbstractHexokinase is the first enzyme in the glycolytic pathway and utilizes ATP to convert glucose to glucose‐6‐phosphate (G6P). We previously identified three variant transcripts of Hk1 that are expressed specifically in spermatogenic cells, have different 5′ untranslated regions, and encode a protein (HK1S, spermatogenic cell‐specific type 1 hexokinase) in which the porin‐binding domain (PBD) of HK1 is replaced by a novel N‐terminal spermatogenic cell‐specific region (SSR). However, the level of expression of the individual variant transcripts or of the other members of the hexokinase gene family (Hk2, Hk3, and Gck) in spermatogenic cells remains uncertain. We show that Hk1, Hk2, and Hk3 transcripts levels are quite low in spermatocytes and spermatids and Gck transcripts are relatively abundant in spermatids, but that glucokinase (GCK) is not detected in spermatozoa. Using real time RT‐PCR (qPCR) with primers specific for each of the three variant forms and RNA from whole testis and isolated germ cells, we found that transcripts for Hk1_v2 and Hk1_v3, but not for Hk1_v1, are relatively high in spermatids. Similar results were seen using spermatogenic cells isolated by laser‐capture microdissection (LCM). Immunoblotting studies found that HK1S is abundant in sperm, and immunostaining confirmed that HK1S is located mainly in the principal piece of the sperm flagellum, where other spermatogenic cell‐specific glycolytic enzymes have been found. These results strongly suggest that HK1, HK2, HK3, and GCK are unlikely to have a role in glycolysis in sperm and that HK1S encoded by Hk1_v2 and Hk1_v3 serves this role. Mol. Reprod. Dev. 75: 632–640, 2008. © 2007 Wiley‐Liss, Inc.
Correlation of urinary nerve growth factor level with pathogenesis of overactive bladder
Authors: Yokoyama Teruhiko , Kumon Hiromi , Nagai Atsushi 
Published: October 2007

AbstractAimsThe origin of overactive bladder (OAB), which is a leading cause of lower urinary tract symptoms, remains unknown. Nerve growth factor (NGF) is one of the neurotrophic factors which are needed for the maintenance of sensory neurons. It is known that too much expression of NGF may induce bladder hyperactivity. In this study, we explored the correlation of the level of urinary NGF with various pathogenic OAB such as idiopathic, neurogenic OAB, and bladder outlet obstruction (BOO).MethodsThe study group included 51 OAB patients. Thirteen patients (7 females and 6 males) had idiopathic detrusor overactivity (DO) without BOO, 6 female idiopathic OAB without DO (sensory urgency), 16 patients with BOO due to BPH, and 16 patients with neurogenic DO (10 due to spinal cord injury (SCI), 6 due to cerebrovascular disease (CVD)). Thirty‐two patients who had normal cystometric findings (23 females and 9 males) without OAB symptoms were used as controls. Urinary NGF levels were measured by enzyme‐linked immunosorbent assay technique (ELISA) and the results were normalized based on creatinine (Cr) concentration.ResultsThe urinary NGF levels in patients with neurogenic DO due to SCI, BOO, and sensory urgency were significantly higher compared with those of normal cystometric finding patients. However, the levels of urinary NGF were not statistically significant between patients with idiopathic DO without BOO, neurogenic DO due to CVD and patients with normal cystometric findings.ConclusionsThese data suggest that urinary NGF levels could serve as a basis for adjunct diagnosis of OAB. Neurourol. Urodynam. 27:417–420, 2008. © 2007 Wiley‐Liss, Inc.
Impact of field strength and iron oxide nanoparticle concentration on the linearity and diagnostic accuracy of off‐resonance imaging
Authors: Farrar Christian T. , Dai Guangping , Novikov Mikhail , Rosenzweig Anthony , Weissleder Ralph , Rosen Bruce R. , Sosnovik David E. 
Published: October 2007

AbstractOff‐resonance imaging (ORI) techniques are being increasingly used to image iron oxide imaging agents such as monocrystalline iron oxide nanoparticles (MION). However, the diagnostic accuracy, linearity, and field dependence of ORI have not been fully characterized. In this study, the sensitivity, specificity, and linearity of ORI were thus examined as a function of both MION concentration and magnetic field strength (4.7 and 14 T). MION phantoms with and without an air interface as well as MION uptake in a mouse model of healing myocardial infarction were imaged. MION‐induced resonance shifts were shown to increase linearly with MION concentration. In contrast, the ORI signal/sensitivity was highly non‐linear, initially increasing with MION concentration until T2 became comparable to the TE and decreasing thereafter. The specificity of ORI to distinguish MION‐induced resonance shifts from on‐resonance water was found to decrease with increasing field because of the increased on‐resonance water linewidths (15 Hz at 4.7 T versus 45 Hz at 14 T). Large resonance shifts (∼300 Hz) were observed at air interfaces at 4.7 T, both in vitro and in vivo, and led to poor ORI specificity for MION concentrations less than 150 µg Fe/mL. The in vivo ORI sensitivity was sufficient to detect the accumulation of MION in macrophages infiltrating healing myocardial infarcts, but the specificity was limited by non‐specific areas of positive contrast at the air/tissue interfaces of the thoracic wall and the descending aorta. Improved specificity and linearity can, however, be expected at lower fields where decreased on‐resonance water linewidths, reduced air‐induced resonance shifts, and longer T2 relaxation times are observed. The optimal performance of ORI will thus likely be seen at low fields, with moderate MION concentrations and with sequences containing very short TEs. Copyright © 2007 John Wiley & Sons, Ltd.
Strongly coupled versus uncoupled spin response to radio frequency interference effects: application to glutamate and glutamine in spectroscopic imaging
Authors: Snyder Jeff , Thompson Richard B. , Wild Jim M. , Wilman Alan H. 
Published: October 2007

AbstractIt is well known that comparable radio frequency (RF) wavelengths and human head dimensions at high fields can lead to an inhomogeneous RF field when using standard RF transmission. However, the impact of RF inhomogeneity on potential differences in quantification between coupled and uncoupled spins at longer echo times has not been investigated thoroughly. The consequence of this RF interference on metabolite quantification in spectroscopic imaging at 4.7 T was investigated for the strongly coupled spin systems of glutamate and glutamine at an echo time of 120 ms, and compared with the singlet response of choline. These effects were studied using a single‐voxel PRESS sequence (α–2α–2α) with varying flip angle (α) from 90° to 65° in simulation, phantom, and in vivo experiments. Phantom metabolite yield decreased to 57% for choline and 27% for glutamate/glutamine in agreement with the simulations. Even a minor reduction from α = 85° to 80° produced a large difference between coupled and uncoupled yields, with a reduction of 7% for choline and 17% for glutamate/glutamine. Anecdotal in vivo spectroscopic imaging studies show similar trends, with large differences between choline and glutamate/glutamine yield over a small, 2.2 cm, region. These results demonstrate severe effects on metabolite yield due to RF variation between strongly coupled and uncoupled spin systems at long echo time, which complicates metabolite quantification. Copyright © 2007 John Wiley & Sons, Ltd.
Inverse formulation for geometrically exact stress resultant shells
Authors: Zhou Xianlian , Lu Jia 
Published: October 2007

AbstractThe inverse elastostatic method deals with a class of problems in which a deformed configuration of an elastic body is known while the initial stress‐free configuration or the stress in the deformed state is to be determined. The method is imperative for certain problems in engineering applications. Computational methods of inverse elastostatics have been established for elastic continua. In this paper, we present an inverse method for thin‐wall structures modeled as geometrically exact stress resultant shells. The theoretical basis and the details of implementation are discussed. Numerical examples involving both isotopic and anisotropic materials are presented. The practical utility of the method is demonstrated using an example of human aneurysm stress analysis. Copyright © 2007 John Wiley & Sons, Ltd.
Delay‐dependent guaranteed cost gain‐scheduling control of LPV state‐delayed systems
Authors: Kucukdemiral I. B. 
Published: October 2007

AbstractDelay‐dependent gain‐scheduling controller design problem is addressed for the linear parameter‐varying state‐delayed systems with time‐varying delays. By choosing a Lyapunov–Krakovskii functional, delay‐dependent conditions for the existence of guaranteed cost gain‐scheduling controller are obtained. Besides, an algorithm is also presented to solve resultant nonconvex matrix inequalities in terms of linear matrix inequalities. Finally, three numerical examples with simulations are illustrated in order to demonstrate the validity of the proposed method. Copyright © 2007 John Wiley & Sons, Ltd.
Micromechanisms involved in the atypical tensile behavior observed in polyamide 11 at high temperature
Authors: Roguet E. , Tencé‐Girault S. , Castagnet S. , Grandidier J.C. , Hochstetter G. 
Published: October 2007

AbstractEven far above the glass transition temperature, the amorphous phase in semicrystalline polymers is known to be constrained by crystals and less mobile than a pure amorphous polymer close to its equilibrium rubbery state. The aim of this paper devoted to Polyamide 11 was to investigate the existence and significance of a relaxed state in the amorphous phase of a semicrystalline polymer far above Tg. It focuses on the high temperatures, low strain‐rates, and small deformation ranges. A nonstrain‐rate dependent tensile curve (called “asymptotic curve”) was evidenced below a critical strain‐rate, consistently with reaching a fully relaxed state of the rubbery amorphous phase. Nevertheless, paradoxical mechanical features were observed at the same time (nonstrain‐rate dependent but hysteretic unloading, relaxation, and creep involving same strain‐rates as the asymptotic loading regime). Micromechanisms (orientation of primary crystals, creation of local hexagonal arrangements, orientation, and relaxation of the amorphous phase) were analyzed from DSC and X‐ray experiments. It suggested distinct amorphous and crystalline contributions depending on the loading path and therefore highlighted paradox of the mechanical behavior. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3046–3059, 2007
Solid state NMR characterization of formation of poly(ϵ‐caprolactone)/maghnite nanocomposites by in situ polymerization
Authors: Haouas Mohamed , Harrane Amine , Belbachir Mohamed , Taulelle Francis 
Published: October 2007

AbstractResults of multinuclear MAS NMR spectroscopy are reported for poly (ε‐caprolactone)/maghnite nanocomposite formation, with ε‐caprolactone in situ polymerized in the presence of maghnite, a proton exchanged montmorillonite clay. Exfoliated and intercalated materials with different maghnite loading in the range 3–15 wt % were investigated. 1H NMR evidences Brønsted acid hydroxyl groups in the silicate layers and shows that their broad signal at 7.6 ppm present in the parent clay disappears in the nanocomposite material. 27Al MAS NMR results show that beside the hexacoordinated aluminum signal, two additional peaks corresponding to two different tetrahedral Al sites are present in the clay framework. The NMR signal intensity of only one of them was found to be affected in the nanocomposites compared with the parent maghnite, suggesting that these specific aluminum sites are the reactive ones at the initial stages of the polymerization. However almost no changes occurred in the 29Si NMR spectra, confirming that the polymer grafting, as indicated earlier by atomic force microscopy, took place on the aluminum tetracoordinated sites rather than on the silicon sites. A mechanism of maghnite surface catalyzed polymerization of ε‐caprolactone was proposed, involving Brønsted and Lewis acid sites. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3060–3068, 2007
Identification, affinity characterisation and biological interactions of lectin‐like peptide–carbohydrate complexes derived from human TNF‐α using high‐resolution mass spectrometry
Authors: Marquardt Andreas , Bernevic Bogdan , Przybylski Michael 
Published: October 2007

AbstractA cyclic disulfide heptadecapeptide (TIP17ox; 2) derived from the lectin‐like 17‐amino acid domain of human tumor necrosis factor‐α [TNF‐α (100–116)] was synthesised and demonstrated to bind specifically to N,N‐diacetylchitobiose, a disaccharide present in many glycan structures of glycoproteins. Although the TIP domain forms a loop structure in the native TNF‐α protein, we show in this study by high‐resolution ESI‐FTICR mass spectrometry that a homologous linear heptadecapeptide (TIP17rd; 1) binds with comparable affinity to chitobiose, suggesting that cyclisation is not essential for carbohydrate binding. ESI‐FTICR‐MS was used as an efficient tool for the direct molecular characterisation of TIP peptide–carbohydrate complexes. The specific binding of the TNF‐TIP domain to chitobiose and other carbohydrate motifs in glycoproteins may explain the high proteolytic stability of these peptides in biological fluids. A considerably higher proteolytic stability in human plasma was found by mass spectrometric analysis for the cyclic TIP peptide 2, compared to the linear peptide 1. Furthermore, affinity‐proteomics studies using immobilised cyclic TIP peptide 2 provided the identification of specific interacting glycoproteins in plasma. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Design, synthesis and evaluation of peptide inhibitors of Mycobacterium tuberculosis ribonucleotide reductase
Authors: Nurbo Johanna , Roos Annette K. , Muthas Daniel , Wahlström Erik , Ericsson Daniel J. , Lundstedt Torbjörn , Unge Torsten , Karlén Anders 
Published: October 2007

AbstractMycobacterium tuberculosis ribonucleotide reductase (RNR) is a potential target for new antitubercular drugs. Herein we describe the synthesis and evaluation of peptide inhibitors of RNR derived from the C‐terminus of the small subunit of M. tuberculosis RNR. An N‐terminal truncation, an alanine scan and a novel statistical molecular design (SMD) approach based on the heptapeptide Ac‐Glu‐Asp‐Asp‐Asp‐Trp‐Asp‐Phe‐OH were applied in this study. The alanine scan showed that Trp5 and Phe7 were important for inhibitory potency. A quantitative structure relationship (QSAR) model was developed based on the synthesized peptides which showed that a negative charge in positions 2, 3, and 6 is beneficial for inhibitory potency. Finally, in position 5 the model coefficients indicate that there is room for a larger side chain, as compared to Trp5. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Conformational studies of vasopressin and mesotocin using NMR spectroscopy and molecular modelling methods. Part II: studies in the SDS micelle
Authors: Rodziewicz‐MotowidŁo Sylwia , Sikorska Emilia , Oleszczuk Marta , Czaplewski Cezary 
Published: October 2007

AbstractThere is much evidence to support the hypothesis that lipids play a role in the interaction of peptide hormones with their membrane receptors. This interaction through change of peptide conformation can facilitate the entry of the hormone into the microenvironment of the receptor. In the present study we have examined the interaction of vasopressin and mesotocin with a lipid—sodium dodecylsulfate (SDS) micelle—using 2D nuclear magnetic resonance (NMR) and theoretical methods. Solution structures of two hormones in solution with SDS were established using the nuclear Overhauser effect (NOE) and the 3JNHHα couplings. The amino acid sequences of these peptides are: c[C1‐Y2‐F3‐Q4‐N5‐C6]‐P7‐R8‐G9‐NH2 ([Arg8]vasopressin, AVP) and c[C1‐Y2‐I3‐Q4‐N5‐C6]‐P7‐I8‐G9‐NH2 (MT). Each of the peptides was found to occur as one stable conformation. AVP adopts the cis configuration on the Cys1‐Tyr2 peptide bond, a finding not reported so far. The three‐dimensional structures of the two peptides studied were determined by a method that consisted of time‐averaged molecular dynamics in an explicit SDS micelle with the parm99 force field in AMBER8.0 package. All calculated structures of the studied peptides form β‐turns in their cyclic parts. The C‐terminal fragment of MT is bent, whereas that of AVP is extended. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.