bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of acidic fluoride solution on β titanium alloy wire
Authors: Kwon Yong Hoon , Seol Hyo‐Joung , Kim Hyung‐Il , Hwang Ki‐Ju , Lee Sang‐Geul , Kim Kyo‐Han 
Published: January 2005

AbstractThe interaction between acidic fluoride solution and β titanium alloy was investigated to explore the changes that occur in β titanium alloy by fluoride‐containing acetic acid solutions. For this, alloy crystal structure, tensile strength, and elements released from the alloy wires were determined using four solutions (0.05%/pH 6, 0.05%/pH 4, 0.2%/pH 6, and 0.2%/pH 4) for 1 or 3 days. The immersed wire did not form any identifiable new crystal structure compared with the as‐received wire. The tensile strength of the immersed wires was significantly reduced compared to the as‐received wires in the test solutions if the period of immersion increased from as‐received to 3 days. The fractured area of the immersed wire was reduced compared to the as‐received one. The dimple pattern at the inner part and a cup–cone morphology at the outer part of the fractured wires were similar in both as‐received and immersed wires. After a 3‐day immersion, the amount of the released Ti and Mo has much increased for higher NaF concentration and lower pH value. During the long‐period orthodontic treatment, both patient and clinical doctor should carefully use the fluoride‐containing products to minimize unexpected damage on orthodontic wires. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater
Dental restorative composites containing 2,2‐bis‐[4‐(2‐hydroxy‐3‐methacryloyloxy propoxy) phenyl] propane derivatives and spiro orthocarbonates
Authors: Moon E.J. , Lee J.Y. , Kim C.K. , Cho B.H. 
Published: January 2005

AbstractVarious dental restorative composite resins containing 2,2‐bis‐[4‐(2‐hydroxy‐3‐methacryloyloxy propoxy) phenyl] propane (Bis‐GMA) derivatives and spiro orthocarbonates (SOCs) were explored for minimizing the volumetric shrinkage that generally occurs during polymerization. Previous reports suggested mixing Bis‐GMA with its derivative TMBis‐GMA (2,2‐bis[3,5‐dimethyl‐4‐(2‐hydroxy‐3‐methacryloyloxy propoxy) phenyl] propane) to obtain a dental composite with low volumetric shrinkage. It was hypothesized that spiro orthocarbonates would expand volumetrically during polymerization, because of their sophisticated ring‐opening reactions; therefore several of them were added to the mixture of Bis‐GMA and TMBis‐GMA to bring about further reductions in volumetric shrinkage. It was indeed possible to reduce the extent of volumetric shrinkage of dental composites containing SOCs, and to do so without compromising these resins' mechanical properties. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater
Endothelin‐1 modulates anterograde fast axonal transport in the central nervous system
Authors: Stokely Martha E. , Yorio Thomas , King Michael A. 
Published: January 2005

AbstractAnterograde fast axonal transport (FAxT) maintains synaptic function and provides materials necessary for neuronal survival. Localized changes in FAxT are associated with a variety of central nervous system (CNS) neuropathies, where they may contribute to inappropriate remodeling, a process more appropriately involved in synaptic plasticity and development. In some cases, developmental remodeling is regulated by localized secretion of endothelins (ETs), neuroinflammatory peptides that are also pathologically elevated in cases of neurologic disease, CNS injury, or ischemia. To investigate the potential role of ETs in these processes, we decided to test whether locally elevated endothelin‐1 (ET‐1) modulates FAxT in adult CNS tissues. We used the established in vivo rat optic nerve model and a novel ex vivo rat hippocampal slice model to test this hypothesis. In vivo, exogenously elevated vitreal ET‐1 significantly affected protein composition of FAxT‐cargos as well as the abundance and peak delivery times for metabolically‐labeled proteins that were transported into the optic nerve. Proteins with molecular weights of 139, 118, 89, 80, 64, 59, 51, 45, 42, 37, and 25 kDa were evaluated at injection‐sacrifice intervals (ISIs) of 24, 28, 32, and 36 hr. In acute hippocampal slices maintained on nonvascular supplies of glucose and oxygen, ET‐1 significantly decreased the distance traveled along the Schaffer collateral tract by nonmetabolically‐labeled lipid rafts at 5 and 10 min after pulse‐labeling. In both models, ET‐1 significantly affected transport or targeted delivery of FaxT‐cargos, suggesting that ET‐1 has the potential to modulate FAxT in adult CNS tissues. © 2005 Wiley‐Liss, Inc.
A humanin derivative, S14G‐HN, prevents amyloid‐β‐induced memory impairment in mice
Authors: Tajima Hirohisa , Kawasumi Masaoki , Chiba Tomohiro , Yamada Marina , Yamashita Kaoru , Nawa Mikiro , Kita Yoshiko , Kouyama Keisuke , Aiso Sadakazu , Matsuoka Masaaki , Niikura Takako , Nishimoto Ikuo 
Published: January 2005

AbstractHumanin (HN) is a 24‐amino acid peptide that protects neuronal cells from death caused by Alzheimer's disease (AD)‐related genes and amyloid‐β (Aβ). Multiple studies have revealed its biochemical and neuroprotective characteristics in vitro; however, little has been known regarding whether HN is effective in vivo in AD model systems. We examined the effect of S14G‐HN, a 1,000‐fold more potent derivative of HN in vitro, on amnesia induced by Aβ25–35 in mice. The Y‐maze test revealed that at least 50 pmol of S14G‐HN by intracerebroventricular injection prevented Aβ‐induced impairment of short‐term/spatial working memory; however, 5 nmol of S14A‐HN, a neuroprotection‐defective mutant in vitro, did not prevent Aβ‐induced amnesia. These results are in agreement with the structure–function correlation shown previously in vitro. In the water‐finding task, S14G‐HN prevented prolongation of finding latency (the time to find water) observed in Aβ‐amnesic mice, indicating that S14G‐HN also blocked Aβ‐induced impairment of latent learning. In accordance with these observations, immunohistochemical analysis showed that S14G‐HN sustained the number of cholinergic neurons in the basal forebrain and the striata nearly to the normal level. Furthermore, genistein, a specific inhibitor of tyrosine kinases, blocked recovery from scopolamine‐induced amnesia by S14G‐HN, suggesting that certain tyrosine kinase(s) are involved in the inhibitory function of S14G‐HN in vivo. Taking these findings together, we conclude that S14G‐HN has rescue activity against memory impairment caused by AD‐related insults in vivo by activating the same intracellular neuroprotective machinery as elucidated previously in vitro. © 2005 Wiley‐Liss, Inc.
γ‐glutamylcysteine ethyl ester‐induced up‐regulation of glutathione protects neurons against Aβ(1–42)‐mediated oxidative stress and neurotoxicity: Implications for Alzheimer's disease
Authors: Boyd‐Kimball Debra , Sultana Rukhsana , Abdul Hafiz Mohmmad , Butterfield D. Allan 
Published: January 2005

AbstractGlutathione (GSH) is an important endogenous antioxidant found in millimolar concentrations in the brain. GSH levels have been shown to decrease with aging. Alzheimer's disease (AD) is a neurodegenerative disorder associated with aging and oxidative stress. Aβ(1–42) has been shown to induce oxidative stress and has been proposed to play a central role in the oxidative damage detected in AD brain. It has been shown that administration of γ‐glutamylcysteine ethyl ester (GCEE) increases cellular levels of GSH, circumventing the regulation of GSH biosynthesis by providing the limiting substrate. In this study, we evaluated the protective role of up‐regulation of GSH by GCEE against the oxidative and neurotoxic effects of Aβ(1–42) in primary neuronal culture. Addition of GCEE to neurons led to an elevated mean cellular GSH level compared with untreated control. Inhibition of γ‐glutamylcysteine synthetase by buthionine sulfoximine (BSO) led to a 98% decrease in total cellular GSH compared with control, which was returned to control levels by addition of GCEE. Taken together, these results suggest that GCEE up‐regulates cellular GSH levels which, in turn, protects neurons against protein oxidation, loss of mitochondrial function, and DNA fragmentation induced by Aβ(1–42). These results are consistent with the notion that up‐regulation of GSH by GCEE may play a viable protective role in the oxidative and neurotoxicity induced by Aβ(1–42) in AD brain. © 2005 Wiley‐Liss, Inc.
Subcellular localization of neural‐specific NPDC‐1 protein
Authors: Evrard C. , Rouget P. 
Published: January 2005

AbstractNPDC‐1 is a gene specifically expressed in neural cells when they stop to divide and begin to differentiate. Immunocytochemical study analysis of differentiated PC12 cells transfected with NPDC‐tag vectors showed that NPDC‐1 is transported in vesicles from the Golgi apparatus to the cell membrane and is then likely internalized into endosomes. The protein colocalized, at least partially, with synaptic vesicle proteins: synaptophysin, synaptobrevin 2, and Rab3 GEP (Rab3 GTP/GDP exchange protein). Moreover, subcellular fractionation of rat brain showed that crude synaptic membrane and crude synaptic vesicle fractions were enriched in NPDC‐1. Although NPDC‐1 bound Rab3 GEP in vitro, it seems unlikely to be involved in Ca2+‐dependent exocytosis and, thus, in synaptic vesicle trafficking. © 2005 Wiley‐Liss, Inc.
Raman and pulse radiolysis studies of the antioxidant properties of quercetin: Cu(II) chelation and oxidizing radical scavenging
Authors: Torreggiani Armida , Trinchero Andrea , Tamba Maurizio , Taddei Paola 
Published: January 2005

AbstractQuercetin (Querc), a pentahydroxyflavonol, is suggested to give protection to living organisms by both direct scavenging of free radicals and metal chelation. The scavenging ability of Querc towards oxidizing radicals, such as •OH, N3• and NO2•, was evaluated by pulse radiolysis studies in aqueous solutions at different pH. Phenoxyl radicals are the final transient products and are formed either by water elimination from •OH‐adducts or by one‐electron transfer from the deprotonated OH groups. Their formation rate is strongly affected by pH and reaches the maximum values in alkaline medium. The Raman and IR spectra were useful to assess the relevant interaction of Querc with Cu(II) ions, which play an important role in the metal‐catalysed generation of reactive oxygen species. Depending on pH and the metal‐to‐ligand ratio, the different chelating sites of Querc change their ability to complex copper ions. Under neutral conditions, the 5‐OH group of ring A and CO‐4 of ring C have a chelating power superior to that of the catechol group (ring B), whereas the complexation in alkaline medium occurs in the reverse order. In addition, experiments with Querc and Zn(II) ions, carried out at basic pH in order to verify the possible Cu(II)‐catalysed oxidation of the ligand, indicated the absence of the above process. Copyright © 2005 John Wiley & Sons, Ltd.
NMR Investigation of the Main‐Chain Orientation in Liquid‐Crystalline Side‐Chain Polymers
Authors: Hempel Günter , Schneider Horst 
Published: January 2005

AbstractThe main‐chain orientation in different groups of liquid‐crystalline side‐chain polymers was investigated using several NMR techniques. For two polyesters the average orientation of the main chain in dependence on the main‐chain spacer length could be found from 2D PASS experiments. In polysiloxanes with different mesogenic side groups and different spacer lengths this information could be received from chemical shift anisotropy measurements. Additionally, application of a modified β‐echo allowed the separation of the dipolar 29Si‐29Si interaction and to characterize the transversal anisotropy of the main‐chain segments. Comparison with small angle neutron scattering results gave good agreement, where the different length scale of both methods has to be taken into account.
NMR Microscopy of an “Anisotropic” Polymer
Authors: Canet D. , Malveau C. , Grandclaude D. , Tekely P. , Beaume F. , Germain Y. 
Published: January 2005

AbstractTwo different samples of high‐density polyethylene (HDPE) have been studied. One (isotropic) is extracted from the material core whereas the other (anisotropic) involves two sides which have been in contact with the injection mold. It is observed by NMR microscopy (using radiofrequency field gradients) that these two sides favor toluene penetration into the material. The distribution of toluene nuclear spin relaxation times (extracted from proton T1 and T2 images) exhibits likewise important differences between the two samples. These differences can be accounted for by partial molecular ordering at the vicinity of the “mold sides”. Finally, in investigating the anisotropic sample (without solvent), three different phases (two amorphous and one crystalline) are revealed by 13C chemical shift imaging experiments (performed with radiofrequency field gradients under CP/MAS conditions). Each amorphous component is preferentially present at one of the two “mold sides”.
Infrared Analysis of Elastomeric Composites under Uniaxial Extension
Authors: Bokobza Liliane 
Published: January 2005

AbstractThe orientational ordering taking place upon deforming uniaxially elastomeric networks is detected and quantified by infrared dichroism. The type of information gained from orientational measurements is discussed in the case of pure networks and also in rubber composites. This information, compared to that obtained from mechanical measurements, provided a better understanding of the molecular processes involved in rubber reinforcement.
Diffusion of Rod‐Like Polypeptides in the Liquid Crystalline and Isotropic Phases as Studied by High Field‐Gradient NMR Spectroscopy
Authors: Ando Isao , Yin Yige , Zhao Chenhua , Kanesaka Sho , Kuroki Shigeki 
Published: January 2005

AbstractIn this lecture the measurements and analyses of the isotropic and anisotropic diffusion coefficients(D) of rod‐like polypeptide such as poly(γ‐L‐glutamate)(PLG) with n‐alkyl side chains, of which the main chain takes the α‐helical conformation, as a function of the main chain length in the thermotropic and lyotropic liquid crystalline phases over a wide range of temperatures from 30 to 80°C by means of pulse high field‐gradient spin echo 1H NMR method have been introduced. In the anisotropic diffusion, the D∥ value in direction parallel to the α‐helical chain axis is found to be much larger than the D⊥ value in direction perpendicular to the α‐helical chain axis. The diffusion process is followed by the Kirkwood theory. Further, it is described that the diffusion in the nematic liquid crystalline phase is much slower than that in the isotropic phase.
Raman and Wide‐Angle X‐Ray Diffraction Studies on Molecular Structure, Crystallinity, and Morphology of Uncompatibilized and Compatibilized Blends of High Molecular Weight Polyethylene/Nylon 12
Authors: Sato Harumi , Isogai Misayo , Sasao Shigehiro , Matsukawa Kimihiro , Kita Yasuo , Yamaguchi Hiroshi , Siesler Heinz W. , Ozaki Yukihiro 
Published: January 2005

AbstractMolecular structure, crystallinity and morphology of uncompatibilized and compatibilized blends of high molecular weight polyethylene (HMWPE) and Nylon 12 were investigated by using Fourier‐transform (FT) Raman spectroscopy, wide‐angle x‐ray diffraction (WAXD), and scanning electron microscopy (SEM). One of the important purposes of the present study is to compare the present results for HMWPE/Nylon 12 with the previously obtained results for high‐density polyethylene (HDPE/Nylon 12). Uncompatibilized and compatibilized blends of HMWPE/Nylon 12 with a Nylon 12 content ranging from 10 to 90 wt% at increments of 10 wt% were prepared. The compatibilized polymer blends were prepared by adding a small amount of maleic anhydride (MAH), and SEM images show that the addition of the small amount of MAH (0.5 wt%) yields a marked improvement of dispersion of HMWPE and Nylon 12. To evaluate the crystallinity of HMWPE from Raman spectra, the relative intensities of bands at 1418 and 1129 cm−1 to the intensity of a band at 1000 cm−1 (I1418/I1000 and I1129/I1000) were estimated for all the uncompatibilized and compatibilized blends of HMWPE/Nylon 12. From the comparison of the relative intensities (I1418/I1000 and I1129/I1000) between the uncompatibilized and compatibilized blends of HMWPE/Nylon 12 it was found that when the Nylon 12 content reaches 40 wt% the crystallinity of HMWPE in the compatibilized blends becomes higher than that of HMWPE in the uncompatibilized blends. The uncompatibilized and compatibilized blends of HMWPE/Nylon 12 (50/50) show quite different x‐ray diffraction patterns; the compatibilized blend shows a significantly larger orientational effect in the x‐ray pattern of HMWPE. It seems that the increase of interaction of MAH‐HMWPE with the Nylon 12 matrix leads to the additional crystallinity.
Study of Molecular Orientation by Vibrational Spectroscopy: From Polymers to Silk
Authors: Pellerin Christian , Rousseau Marie‐Eve , Côté Mathieu , Pézolet Michel 
Published: January 2005

AbstractInfrared and Raman spectroscopies are very efficient techniques to characterize molecular orientation in macromolecular systems. In the present paper, two examples of the application of vibrational spectroscopy to the study of molecular orientation in synthetic and natural macromolecules will be presented. In the first example, the dynamics of orientation and relaxation of stretched films of bimodal blends of polystyrene (PS) and deuterated polystyrene (dPS) has been studied in situ by polarization modulation infrared linear dichroism while, in the second one, polarized Raman microspectroscopy has been used to determined quantitatively the orientation of β‐sheet domains in single filaments of Bombyx mori silk.
NMR as a Probe into the Local and Semilocal Order in Cooperative Interactions of Polyelectrolytes
Authors: Kříž Jaroslav 
Published: January 2005

AbstractPolyelectrolytes such as poly(N‐diallyldimethylammonium chloride) (PDADMAC) exhibit some local and semilocal order both in their conformation dynamics (dynamic correlations) and the average density of their counterion cloud (the radial density distribution). Both aspects of order are subject to cooperative fluctuations as well as mutual reinforcement. They can be observed in particular in dilute solutions, i.e. at concentrations of the charged groups less than 5 mmol/L. At such dilution, 1H NMR is the method of choice for the study of conformation dynamics. In addition to the recently published analysis of transverse relaxation and saturation transfer experiments, relaxations of double‐quantum coherence, pseudo‐solid echo and solid echo responses and exchange 2D spectra are reported here. For the radial distribution of counterions with spin‐3/2 nuclei (7Li, 23Na, 35Cl, 81Br), the relaxation model proposed by Halle, Wennerstrom and Picullel is applied and the use of either combined longitudinal and transverse relaxation or DQC (T23) relaxation is shown. The results show that the counterion condensation, i.e. relative ordering of the counterion cloud, decreases in less densely charged polyions and vanishes for the charge separation about 2.5 nm.
Shear‐Induced Order in Nematic Polymers
Authors: Becker Patrick , Siebert Hartmut , Noirez Laurence , Schmidt Claudia 
Published: January 2005

AbstractSeveral nematic side‐chain polysiloxanes with the same backbone and the same mesogens but containing various ratios of two spacers having different lengths were prepared. Within this series of homo‐ and copolymers, the phase behavior changes continuously from purely nematic for the homopolymer containing only the shorter of the two spacers to nematic plus smectic for the homopolymer containing only the longer spacer. The flow behavior determined by in situ deuterium NMR spectroscopy under shear and the anisotropy of the coil conformation measured by small angle neutron scattering exhibit a continuous change as well.
Vibrational Spectroscopy of Ion Irradiated Carbon Containing Macromolecules
Authors: Strazzulla Giovanni , Baratta Giuseppe , Brunetto Rosario , Cataldo Franco 
Published: January 2005

AbstractA large variety of carbon rich macromolecules has been studied in our laboratory, before, during, and after ion irradiation (3‐60 keV ions), by in situ IR and Raman spectroscopies. In this paper we present results obtained on: (a) Films of frozen H2O:CH4:N2 mixtures that have been deposited at low temperature (12 K) on a silicon substrate, and irradiated with fast ions. Irradiation causes the formation of organic refractory residues whose spectra have been recorded and studied also after further irradiation at room temperature. (b) Pentacene (a Polyciclic Aromatic Hydrocarbon, PAH) whose Raman spectra have been studied also during ion irradiation at room temperature. (c) Thin samples of fullerene (C60) films also irradiated at room temperature.Here we discuss some of the most relevant results and compare the spectra of the very different samples that after prolonged irradiation, evolve towards amorphous carbons that have common spectral characteristic. The results are discussed in terms of their astrophysical relevance. It is demonstrated that frozen hydrocarbons, PAHs and fullerenes are rapidly converted to amorphous carbon in space. Amorphous carbon has to be a widespread material in many astrophysical environments.
Structure elucidation and complete NMR spectral assignments of a new benzoxazolinone glucoside from Acanthus ilicifolius
Authors: Huo Changhong , An Dongge , Wang Bin , Zhao Yuying , Lin Wenhan 
Published: January 2005

AbstractA new benzoxazolinone glucoside, 4‐O‐β‐D‐glucopyranosyl‐benzoxazolin‐2(3H)‐one, was isolated from Acanthus ilicifolius, a medicinal plant from south China. The complete 1H and 13C NMR assignments of the compound were carried out by using DEPT, HMBC, HMQC, NOESY and 1H1H COSY spectra. Copyright © 2005 John Wiley & Sons, Ltd.
Study of the behaviour of amino acids in aqueous solution by time‐domain NMR and high‐resolution NMR
Authors: Khallouk M. , Rutledge D. N. , Silva A. M. S. , Delgadillo I. 
Published: January 2005

AbstractThe study of protein hydration by time‐domain NMR is complicated by the great number of interactions involved, resulting from the presence of several amino acids and the possible modifications produced by the various structures. Moreover, a good comprehension of the molecular interactions of the simple amino acids in solution is essential to elucidate the mechanism of the biological functions of proteins. Measurements of transverse relaxation rates of the protons of water (R2 = 1/T2) in aqueous solutions of amino acids such as L‐glycine, L‐asparagine, L‐arginine and L‐tryptophan were carried out in order to study the effects of chemical exchange and molecular diffusion on the amplitude of R2. The values of R2 measured by the Carr–Purcell–Meiboom–Gill (CPMG) sequence were studied while varying the solution pH and the parameters of the CPMG sequence. The dependence of R2 on pH and τ (inter‐pulse delay between the first and the second pulses of the CPMG sequence) is interpreted in terms of chemical exchange between the protons of water and those of the labile amino acid groups. This interpretation was confirmed by the analysis of the proton spectra acquired using a 300 MHz NMR spectrometer. Copyright © 2005 John Wiley & Sons, Ltd.
Measurement of 1J(Ni,Cαi), 1J(Ni,C′i−1), 2J(Ni,Cαi−1), 2J(HNi,C′i−1) and 2J(HNi,Cαi) values in 13C/15N‐labeled proteins
Authors: Mukherjee Sulakshana , Mustafi Sourajit M. , Atreya H. S. , Chary K. V. R. 
Published: January 2005

AbstractUse of partial or selective 13C/15N labeling of specific amino acid residues in a given protein to measure the values of 1J(15Ni,13Cαi), 2J(1HN,13Cαi), 2J(15Ni,13Cαi−1), 1J(15Ni,13C′i−1) and 2J(1HN,13C′i−1) is described. This was achieved by recording a sensitivity‐enhanced 2D [15N–1H] HSQC experiment, without mixing the spin states of Cα and C′ during the course of entire experiment. Copyright © 2005 John Wiley & Sons, Ltd.