bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lack of aspartoacylase activity disrupts survival and differentiation of neural progenitors and oligodendrocytes in a mouse model of Canavan disease
Authors: Kumar Shalini , Biancotti Juan Carlos , Matalon Reuben , de Vellis Jean 
Published: September 2009

AbstractLoss of the oligodendrocyte (OL)‐specific enzyme aspartoacylase (ASPA) from gene mutation results in the sponginess and loss of white matter (WM) in Canavan disease (CD). This study addresses the fate of OLs during the pathophysiology of CD in an adult ASPA knockout (KO) mouse strain. Massive arrays of neural stem/progenitor cells, immunopositive for PSA‐NCAM, nestin, vimentin, and NG2, were observed within the severely affected spongy WM of the KO mouse brain. In these mice, G1→S cell cycle progression was confirmed by an increase in cdk2‐kinase activity, a reduction in mitotic inhibitors p21Cip1 and p27Kip1, and an increase in bromodeoxyuridine (BrdU) incorporation. Highly acetylated nuclear histones H2B and H3 were detected in adult KO mouse WM, suggesting the existence of noncompact chromatin as seen during early development. Costaining for BrdU‐ or Ki67‐positive cells with markers for neural progenitors confirmed a continuous generation of OL lineage cells in KO WM. We observed a severe reduction in 21.5‐ and 18.5‐kDa myelin basic protein and PLP/DM20 proteolipid proteins combined with a decrease in myelinated fibers and a perinuclear retention of myelin protein staining, indicating impairment in protein trafficking. Death of OLs, neurons, and astrocytes was identified in every region of the KO brain. Immature OLs constituted the largest population of dying cells, particularly in WM. We also report an early expression of full‐length ASPA mRNA in normal mouse brain at embryonic day 12.5, when OL progenitors first appear during development. These findings support involvement of ASPA in CNS development and function. © 2009 Wiley‐Liss, Inc.
Neural cell adhesion molecule stimulates survival of premyelinating oligodendrocytes via the fibroblast growth factor receptor
Authors: Palser Anne L. , Norman Adele L. , Saffell Jane L. , Reynolds Richard 
Published: September 2009

AbstractAxonal signals are critical in promoting the survival and maturation of oligodendrocytes during myelination, with contact‐dependent signals thought to play a key role. However, the exact nature of these signals remains unclear. Neural cell adhesion molecule (NCAM) is expressed by both axons and oligodendrocytes and is ideally localized to transduce signals from the axon. This study sought to investigate the influence of NCAM on premyelinating oligodendrocytes in vitro. Both a soluble molecule comprising the extracellular domain of NCAM and a peptide derived from the fibroblast growth factor receptor (FGFR) binding motif within the first fibronectin domain stimulated a dose‐dependent increase in survival of premyelinating oligodendrocytes in vitro. The survival effect was blocked by a mitogen‐activated protein kinase (MAPK) inhibitor and an FGFR inhibitor, suggesting that activation of MAPK signalling pathways following interaction with the FGFR is involved in the survival effect of NCAM. Furthermore, NCAM presented in a cellular monolayer induced an increase in radial process outgrowth of oligodendrocyte progenitor cells. These data suggest that NCAM may play a role in axon–oligodendrocyte signalling during myelination, leading to an increase in oligodendrocyte survival and process outgrowth following axonal contact. © 2009 Wiley‐Liss, Inc.
Molecular structure, vibrational spectroscopic, first‐order hyperpolarizability and HOMO, LUMO studies of 3‐hydroxy‐2‐naphthoic acid hydrazide
Authors: Karpagam J. , Sundaraganesan N. , Sebastian S. , Manoharan S. , Kurt M. 
Published: September 2009

AbstractThe Fourier‐transform infrared spectrum of 3‐hydroxy‐2‐naphthoic acid hydrazide (3H2NAH) was recorded in the region 4000–400 cm−1. The Fourier‐transform Raman spectrum of 3H2NAH was also recorded in the region 3500–10 cm−1. Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of 3H2NAH were carried out by density functional theory (DFT/B3LYP) method with 6‐31G(d,p) as basis set. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The values of the electric dipole moment (µ) and the first‐order hyperpolarizability (β) of the investigated molecule were computed using ab initio quantum mechanical calculations. The UV spectrum was measured in ethanol solution. The calculation results also show that the 3H2NAH molecule might have microscopic nonlinear optical (NLO) behavior with non‐zero values. A detailed interpretation of the infrared and Raman spectra of 3H2NAH is also reported based on total energy distribution (TED). The calculated HOMO and LUMO energies shows that charge transfer occur within the molecule. The theoretical FT‐IR and FT‐Raman spectra for the title molecule have also been constructed. Copyright © 2009 John Wiley & Sons, Ltd.
Raman spectra of nitrogen‐containing organic compounds obtained using a portable instrument at −15 °C at 2860 m above sea level
Authors: Jehlička J. , Culka A. 
Published: September 2009

AbstractWell‐resolved Raman spectra of samples of nitrogen‐containing compounds were detected using a portable Raman instrument (Ahura First Defender XL) outdoors at a low ambient temperature of −15 °C and at an altitude of 2860 m (Pitztall, Austria). The portable Raman spectrometer tested here is equipped with a 785‐nm diode laser and a fixed frontal probe. Solid form of formamide, urea, 3‐methylpyridine, aniline, indene, 1‐(2‐aminoethyl)piperazine, indoline and benzofuran were detected unambiguously under high‐mountain field conditions. The main Raman features (strong, medium and partially weak bands) were observed at the correct wavenumber positions (with a spectral resolution 7–10 cm−1) in the wavenumber range 200–1600 cm−1. The results obtained demonstrate the possibility of employing a miniaturised Raman spectrometer as a key instrument for investigating the presence of nitrogen‐containing organic compounds and biomolecules outdoors under low temperature conditions. Within the payload designed by European Space Agency (ESA) and National Aeronautics and Space Administration (NASA) for future missions, focussing not only on Mars, Raman spectroscopy represents an important instrumentation for the detection of organic nitrogen‐containing compounds relevant to life detection on planetary surfaces or near sub‐surfaces. Copyright © 2009 John Wiley & Sons, Ltd.
Can Raman spectroscopy detect cumulenic structures of linear carbon chains?
Authors: Innocenti Francesco , Milani Alberto , Castiglioni Chiara 
Published: September 2009

AbstractThe molecular and vibrational structures of cumulenic carbon chains are investigated by density functional theory calculations and compared with that of hydrogen‐capped polyynes. The small value of bond length alternation (BLA) along the CC bonds sequence obtained by geometry optimization of uncapped Cn chains and vinyl‐capped carbon chains confirms their cumulenic structure. It is demonstrated that for finite length chains the structural parameters are determined by end effects as far as the Peierls distortion, expected for very long molecules, does not occur. The Raman spectra of such molecules are calculated to verify the possibility of identifying markers of cumulenic chains by means of vibrational spectroscopy. As expected, the longitudinal mode consisting of the BLA oscillation, which is responsible for the strongest Raman transition of polyynes, becomes very weak for cumulenes; this behaviour is rationalized in terms of local polarizability derivatives. However, other longitudinal modes can be observed in the Raman spectra of Cn chains. The wavenumber behaviour and the optical activity of these modes are interpreted on the basis of the phonon dispersion branch of an ideally infinite cumulenic polymer. Raman intensities computed for chains of different lengths allow to conclude that cumulenic molecules could be detected and identified by means of Raman spectroscopy. Copyright © 2009 John Wiley & Sons, Ltd.
Vibrational spectroscopy study of hydrothermally produced scorodite (FeAsO4·2H2O), ferric arsenate sub‐hydrate (FAsH; FeAsO4·0.75H2O) and basic ferric arsenate sulfate (BFAS; Fe[(AsO4)1−x(SO4)x(OH)x]·wH2O)
Authors: Gomez M. A. , Assaaoudi H. , Becze L. , Cutler J. N. , Demopoulos G. P. 
Published: September 2009

AbstractThree crystalline ferric arsenate phases: (1) scorodite; FeAsO4·2H2O, (2) ferric arsenate sub‐hydrate (FAsH; FeAsO4·0.75H2O) and (3) basic ferric arsenate sulfate (BFAS; Fe[(AsO4)1−x(SO4)x(OH)x]·wH2O) synthesized by hydrothermal precipitation (175–225 °C) from Fe(III)‐AsO43−–SO42− solutions have been investigated via Raman and infrared spectroscopies. The spectroscopic nature of these high‐temperature Fe(III)‐ AsO43−–SO42− phases has not been extensively studied despite their importance to the hydrometallurgical industrial processing of precious metal (Au and Cu) arsenic sulfidic ores. It was found that scorodite, FAsH and BFAS all gave rise to very distinct arsenate, sulfate and hydroxyl vibrations. In scorodite and FAsH, the distribution of the internal arsenate modes was found to be distinct, with the factor effect being more predominant in the crystal system. For the crystallographically unknown BFAS phase, vibrational spectroscopy was used to monitor the arsenate ↔ sulfate solid solution behavior that occurs in this phase where the molecular symmetry of arsenate and sulfate in the crystal structure is reduced from an ideal Td to a distorted Td or C2/C2v symmetry. With the new collected vibrational data of the pure phases, the use of attenuated total reflectance infrared (ATR‐IR) spectroscopy was finally extended to investigate the nature of the arsenate in an industrial residue generated by pressure oxidation of a gold ore, where it was found that the arsenate was present in the form of BFAS. Copyright © 2009 John Wiley & Sons, Ltd.
Molecular imprinting of AMP by an ionic‐noncovalent dual approach
Authors: Breton Florent , Delépée Raphaël , Agrofoglio Luigi A. 
Published: September 2009

AbstractIn order to mimic recognition properties of adenylate kinase, molecularly imprinted polymers (MIPs) were prepared for adenosine 5′‐monophosphate (AMP), a substrate of the enzyme. Different functional monomers interacting with the phosphate moiety were tested, and the MIP giving the best specific binding of AMP was composed with one equivalent of 2‐(dimethylamino)ethyl methacrylate and ten equivalents of acrylamide compared to AMP. Packed into solid phase cartridge, this polymer showed similar characteristics than the enzyme, since it was specific for AMP toward other nucleotides.
Studies towards enantioselective surface imprinted polymers
Authors: Yilmaz Ecevit , Billing Johan , Boyd Brian , Möller Per , Rees Anthony 
Published: September 2009

AbstractMolecularly imprinted polymers (MIPs) are tailor‐made materials that can specifically rebind desired target molecules. Usually, the template is in solution with monomers that form a specific polymeric cavity around the template. Here, a model system with an amino acid (Fmoc‐L‐Histidine) is presented. This new approach entails the imprinting of templates that are bound to support materials. It is shown that the new approach leads to materials that exhibit symmetric peak shapes for both enantiomers under isocratic conditions.
Selective sample pretreatment by molecularly imprinted polymer for the determination of LSD in biological fluids
Authors: Chapuis‐Hugon Florence , Cruz‐Vera Marta , Savane Ramatoulaye , Ali Wassim Hadj , Valcarcel Miguel , Deveaux Marc , Pichon Valerie 
Published: September 2009

AbstractFor the first time, a molecularly imprinted polymer (MIP) was synthesized by a noncovalent imprinting approach for the selective extraction of an illicit drug, LSD, from hair and urine samples. For the synthesis of MIP, an analog of LSD, was taken as a dummy template, methacrylic acid as a functional monomer, and ACN as a porogen solvent. The MIP was used for offline extraction before HPLC‐MS analysis. By studying the interactions taking place between the LSD and the MIP, a selective procedure was established in organic media and applied to hair samples. By this way, 0.1 ng/mg of LSD was successfully detected in hair with 82% of extraction recovery. A low retention was also obtained on the control polymer (only 9%). This procedure was then modified to obtain a selective extraction in aqueous media for the determination of LSD in urine samples. The comparison with a conventional C18 clearly demonstrated the selectivity brought by the MIP to the determination of LSD in urine. LSD was easily detected in urine at only 0.5 ng/mL with 83% of extraction recovery on the MIP and 11% on the NIP. An LOQ of 0.2 pg/mL was estimated in urine samples.
Cartilage myringoplasty
Authors: Klacansky Juraj 
Published: September 2009

AbstractMyringoplasty is considered the simplest reconstructive procedure of the middle ear. There are many variations and types of myringoplasties. In the past, these variations were categorized according to the types of tissue and the way the tissue was fixated in the middle ear. Currently, the types of myringoplasties are differentiated only by the fixation of the transplant, because a majority of ear surgeons use only fascia, perichondrium, or cartilage. The percentage of successful healings after myringoplasties does not depend on the tissue used. More important is the condition of the middle ear at the time of the operation and the experience and skill of the surgeon. Regardless which type of tissue is used, 90% to 95% of good anatomical healing can be achieved. The author of this article performed more than 7,000 cartilage myringoplasties and presents his experience and alternatives of cartilage use in the eardrum reconstructions. He introduces three types of cartilage grafts: 1) island cartilage graft, 2) ring cartilage graft, and 3) double island cartilage graft. Laryngoscope, 2009
Strategies for Zonal Cartilage Repair using Hydrogels
Authors: Klein Travis J. , Rizzi Simone C. , Reichert Johannes C. , Georgi Nicole , Malda Jos , Schuurman Wouter , Crawford Ross W. , Hutmacher Dietmar W. 
Published: September 2009

AbstractArticular cartilage is a highly hydrated tissue with depth‐dependent cellular and matrix properties that provide low‐friction load bearing in joints. However, the structure and function are frequently lost and there is insufficient repair response to regenerate high‐quality cartilage. Several hydrogel‐based tissue‐engineering strategies have recently been developed to form constructs with biomimetic zonal variations to improve cartilage repair. Modular hydrogel systems allow for systematic control over hydrogel properties, and advanced fabrication techniques allow for control over construct organization. These technologies have great potential to address many unanswered questions involved in prescribing zonal properties to tissue‐engineered constructs for cartilage repair.magnified image
Cyclodextrin Complexation for Affinity‐Based Antibiotic Delivery
Authors: Thatiparti Thimma Reddy , von Recum Horst A. 
Published: September 2009

AbstractNovel β‐cyclodextrin polymer (CD)‐based drug delivery hydrogels were prepared by varying type and concentration of crosslinkers and optimizing the gel synthesis conditions. For comparison, dextrose gels were prepared using the same crosslinkers. The optimized gels were characterized by Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), and X‐ray diffraction (XRD) as well as swelling and release studies. For drug release studies, the gels were loaded with three different model antibiotics varying in size and hydrophobicity: rifampin (RM), novobiocin (NB), and vancomycin (VM), using a common solvent method. The loading efficiency was calculated and release kinetics were determined in vitro. As expected for affinity‐based mechanisms, the release of drugs, from CD‐based gels, was slower than release from dextrose gels which indicated that the antibiotics all form inclusion complexes with CD. Release kinetics were also more linear in the observed time frame when using CD‐based hydrogels versus dextrose hydrogels. This modification in release depended on the affinity‐between CD and drug, such that larger drugs and more hydrophilic ones had their release profiles altered less than small hydrophobic ones. In conclusion, affinity‐based mechanisms can be used to load antibiotics and obtain longer, more linear release profiles than purely diffusion‐based mechanisms.magnified image
Studies on corrosion inhibition of copper by alkanethiol SAMs prepared in aqueous micellar solution
Authors: Wang P. , Liang C. , Huang N. 
Published: September 2009

AbstractThe character of 1‐dodecanethiol (DT) self‐assembled monolayers (SAMs) formed on copper surface in aqueous micellar solution is investigated by means of contact angle measurement, electrochemical impedance spectroscopy (EIS), and polarization curves. The contact angle measurement shows that the SAMs formed in aqueous micellar solution are oriented and compact. According to the electrochemical measurements, it is found that both the concentration of DT and temperature can significantly affect the property of SAMs. The DT SAMs can prevent the corrosion of copper in chloride‐containing solution effectively because the inhibition efficiency can reach 99.59% at the DT concentration of 10−2 M. The adsorption of DT in aqueous micellar solution obeys to the Langmuir adsorption isotherm, and the value of the free energy of adsorption calculated indicates that the adsorption of DT molecule is a spontaneous process and a typical of chemical adsorption.
Micelle Behavior of Copolymers Composed of Linear and Hyperbranched Blocks in Aqueous Solution
Authors: Lim Su‐Hoon , Cha Eui‐Joon , Huh June , Ahn Cheol‐Hee 
Published: September 2009

AbstractMulti‐arm poly(THF)‐b‐polyglycerol linear‐hyperbranched copolymers consisting of a linear hydrophobic poly(THF) block and a hyperbranched hydrophilic polyglycerol block were synthesized by ring opening polymerization of tetrahydrofuran with silver trifluoromethane sulfonate as a catalyst and the consecutive polymerization of glycidol. Initiators with different geometries that propagated into different numbers of arms (e.g., 1, 2 or 4) were used to investigate the dependence of the micelle properties of the copolymers on the number of arms. The critical micelle concentration (CMC) first decreased and then increased with increasing numbers of arms showing a minimum CMC at an arm number of 2. A minimum CMC was difficult to obtain using multi‐arm block copolymers composed of linear polymers with the small number of arms investigated in this study. DLS showed that the 4‐arm poly(THF)‐b‐polyglycerol copolymer had a micelle size of approximately 83 nm under aqueous conditions, and the micelle size of the copolymers with different numbers of arms was similar. Unimolecular micelles could eventually be obtained using this system by increasing the number of arms, they are considered an ideal drug delivery carrier due to the concentration‐independent stability in the blood stream.magnified image
A Facile Route to Prepare Organic/Inorganic Hybrid Nanomaterials by ‘Click Chemistry’
Authors: Lu Xunyu , Sun Fu , Wang Jing , Zhong Jianfeng , Dong Qingzhi 
Published: September 2009

AbstractAn organosilane with an alkyne group at the non‐condensable end, [(2‐propynylcarbamate)propyl]triethoxysilane, has been synthesized. Condensation of this organosilane with tetraethoxysilane can be achieved by a co‐condensation strategy to produce silica nanoparticles with surface alkyne functionality. The size and uniformity of size distribution of the silica nanoparticles are influenced by varying the concentration of the added organosilane. The alkyne‐functionalized silica nanoparticles are coupled directly with azide‐modified polymers by ‘click chemistry’ to yield organic–inorganic hybrid nanomaterials.magnified image
On Helmholtz decompositions and their generalizations—An overview
Authors: Sprössig W. 
Published: September 2009

AbstractHelmholtz' theorem initiates a remarkable development in the theory of projection methods that are adapted to the numerical solution of equations in fluid dynamics and elasticity. There is a dense connection with Hodge‐de Rham decompositions of smooth 1‐forms. We give an overview of this type of decompositions and discuss their applications to vector, quaternionic and Clifford‐valued boundary value problems in the corresponding Hilbert–Sobolev spaces. Copyright © 2009 John Wiley & Sons, Ltd.
Work and energy equations and the principle of generalized effective stress for unsaturated soils
Authors: Zhao C. G. , Liu Y. , Gao F. P. 
Published: September 2009

AbstractThe effective stress principle has been efficiently applied to saturated soils in the soil mechanics and geotechnical engineering practice; however, its applicability to unsaturated soils is still under debate. The appropriate selection of stress state variables is essential for the construction of constitutive models for unsaturated soils. Owing to the complexity of unsaturated soils, it is difficult to determine the deformation and strength behaviors of unsaturated soils uniquely with the previous single‐effective‐stress variable theory and two‐effective‐stress‐variable theory in all the situations. In this paper, based on the porous media theory, the specific expression of work is proposed, and the effective stress of unsaturated soils conjugated with the displacement of the soil skeleton is further derived. In the derived work and energy balance equations, the energy dissipation in unsaturated soils is taken into account. According to the derived work and energy balance equations, all of the three generalized stresses and the conjugated strains have effects on the deformation of unsaturated soils. For considering these effects, a principle of generalized effective stress to describe the behaviors of unsaturated soils is proposed. The proposed principle of generalized effective stress may reduce to the previous effective stress theory of single‐stress variable or the two‐stress variables under certain conditions. This principle provides a helpful reference for the development of constitutive models for unsaturated soils. Copyright © 2009 John Wiley & Sons, Ltd.
Complex geometric models of diffusion and relaxation in healthy and damaged white matter
Authors: Landman Bennett A. , Farrell Jonathan A. D. , Smith Seth A. , Reich Daniel S. , Calabresi Peter A. , van Zijl Peter C. M. 
Published: September 2009

AbstractWhich aspects of tissue microstructure affect diffusion weighted MRI signals? Prior models, many of which use Monte‐Carlo simulations, have focused on relatively simple models of the cellular microenvironment and have not considered important anatomic details. With the advent of higher‐order analysis models for diffusion imaging, such as high angular resolution diffusion imaging (HARDI), more realistic models are necessary. This paper presents and evaluates the reproducibility of simulations of diffusion in complex geometries. Our framework is quantitative, does not require specialized hardware, is easily implemented with little programming experience, and is freely available as open‐source software. Models may include compartments with different diffusivities, permeabilities, and T2 time constants using both parametric (e.g. spheres and cylinders) and arbitrary (e.g. mesh‐based) geometries. Three‐dimensional diffusion displacement probability functions are mapped with high reproducibility, and thus can be readily used to assess reproducibility of diffusion‐derived contrasts. Copyright © 2009 John Wiley & Sons, Ltd.