bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stalactite drip rate variations controlled by air pressure changes: an example of non‐linear infiltration processes in the ‘Cueva del Agua’ (Spain)
Authors: Fernández‐Cortés A. , Calaforra J. M. , Sánchez‐Martos F. , Gisbert J. 
Published: August 2006

AbstractA study of drip water from a stalactite in the Cueva del Agua (Granada, southern Spain) over four hydrological years has enabled a detailed characterization of infiltration through the non‐saturated zone of this cave. The most significant aspects are: (1) The drip water regime is not seasonal, but is linked instead to slow infiltration. Sudden changes in the drip water regime are detected, due to infiltration along the preferential flow paths and the draining of water of supersaturated water reserves from the microfissure and pore system. (2) The accumulation of excess rain in the unsaturated zone dislodges the reserve of supersaturated water from the matrix of microfissures and pores, giving rise to an average increase in drip intensity of 2·2 ± 0·5 mm h−1 and 37 ± 13 µS cm−1 in the electrical conductivity of the water. (3) Time‐series analysis of the drip water demonstrates a lack of linearity over time of the drip rate, indicating a chaotic regime. (4) When the dripping is constant, barometric oscillation of the air is the principal factor that causes the lack of linearity in the drip flow. In this way, over an average of 2–3 days, a mean variation of the air pressure inside the cave of 10 ± 3·7 mbar causes a mean oscillation in the drip rate of 0·5 ± 0·2 mm h−1. This increase in air pressure is translated as an increase in the relative thickness of the gaseous phase of the drip water at the cost of the aqueous phase, so reducing the drip intensity of the stalactite. Copyright © 2006 John Wiley & Sons, Ltd.
EPI image reconstruction with correction of distortion and signal losses
Authors: Liu Guoxiang , Ogawa Seiji 
Published: August 2006

AbstractPurposeTo derive and implement a method for correcting geometric distortions and recovering magnetic resonance imaging (MRI) signal losses caused by susceptibility‐induced magnetic field gradients (SFGs) in regions with large static field inhomogeneities in echo‐planar imaging (EPI).Materials and MethodsFactors to account for field inhomogeneities and SFGs were added in a traditional EPI equation that was a simple Fourier transform (FT) for expressing the actual k‐space data of an EPI scan. The inverse calculation of this “distorted EPI” equation was used as a kernel to correct geometric distortions and reductions in intensity during reconstruction. A step‐by‐step EPI reconstruction method was developed to prevent complicated phase unwrapping problems. Some EPI images of phantom and human brains were reconstructed from standard EPI k‐spaces.ResultsAll images were reconstructed using the proposed multistep method. Geometric distortions were corrected and SFG‐induced MRI signal losses were recovered.ConclusionResults suggest that applying our method for reconstructing EPI images to reduce distortions and MRI signal losses is feasible. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Desert water harvesting from takyr surfaces: assessing the potential of traditional and experimental technologies in the Karakum
Authors: Fleskens L. , Ataev A. , Mamedov B. , Spaan W. P. 
Published: August 2006

AbstractFrom historical times the traditionally nomadic people in desert environments of Turkmenistan have applied a range of innovative technologies to secure water supply for consumptive and productive purposes. These technologies make use of takyrs, flat or slightly sloping dense clay surfaces which act as natural catchment areas. In recent history, these technologies have been neglected, in part due to a booming water supply through irrigation development, and takyr surfaces have suffered various degradation processes. However, the limited scope for further extension of irrigation systems presents a challenge to reconsider these traditional technologies. In this paper, results of cost‐benefit analysis are presented by which an assessment is made of the potential of both traditional and experimental takyr use technologies. It is shown that they bear considerable potential for the future at relatively low investment cost, that they may help limit degradation processes and provide for a sustainable development pathway for the inhabitants of the desert. A main challenge in order to benefit from this potential is to find an appropriate management structure for maintenance and resource use of these water‐harvesting technologies. Copyright © 2006 John Wiley & Sons, Ltd.
Modifications of aminoglycoside antibiotics targeting RNA
Authors: Zhou Jian , Wang Guannan , Zhang Li‐He , Ye Xin‐Shan 
Published: August 2006

AbstractThe increased awareness of the central role of RNA has led to realization that RNA, as structural and functional information accumulation, is also drug target to small molecular therapy. Aminoglycosides are a group of well‐known antibiotics, which function through binding to specific sites in prokaryotic ribosomal RNA (rRNA) and affecting the fidelity of protein synthesis. Unfortunately, their clinical practice has been curtailed by toxicity and rapid increasing number of resistant strains. Therefore, it is highly desirable to design new modified aminoglycosides that will overcome the undesirable properties of natural occurring aminoglycosides. On the other hand, aminoglycosides as potential antiviral (HIV) agents were also reported. Herein, we survey the current efforts to develop new aminoglycoside derivatives with modification and reconstruction on each sugar ring and review the latest advances in structure‐activity relationships (SAR). © 2006 Wiley Periodicals, Inc. Med Res Rev, 27, No. 3, 279–316, 2007
Decreased protein tyrosine phosphorylation and membrane fluidity in spermatozoa from infertile men with varicocele
Authors: Buffone M.G. , Brugo‐Olmedo S. , Calamera J.C. , Verstraeten S.V. , Urrutia F. , Grippo L. , Corbetta J.P. , Doncel G.F. 
Published: August 2006

AbstractVaricocele is a prevalent pathology among infertile men. The mechanisms linking this condition to infertility, however, are poorly understood. Our previous work showed a relationship between sperm functional quality and the ability of spermatozoa to respond to capacitating conditions with increased membrane fluidity and protein tyrosine phosphorylation. Given the reported association between varicocele, oxidative stress, and sperm dysfunction, we hypothesized that spermatozoa from infertile patients with varicocele might have a combined defect at the level of membrane fluidity and protein tyrosine phosphorylation. Semen samples from infertile patients with and without grade II/III left varicocele were evaluated for motion parameters (computer‐assisted semen analysis [CASA]), hyperactivation (CASA), incidence and intensity of protein tyrosine phosphorylation (phosphotyrosine immunofluorescence and western blotting), and membrane fluidity (Laurdan fluorometry), before and after a capacitating incubation (6 hr at 37°C in Ham's F10/BSA, 5% CO2). Spermatozoa from varicocele samples presented a decreased response to the capacitating challenge, showing significantly lower motility, hyperactivation, incidence and intensity of tyrosine phosphorylation, and membrane fluidity. The findings reported in this article indicate that the sperm dysfunction associated to infertile varicocele coexists with decreased sperm plasma membrane fluidity and tyrosine phosphorylation. These deficiencies represent potential new pathophysiological mechanisms underlying varicocele‐related infertility. Mol. Reprod. Dev. 73: 1591–1599, 2006. © 2006 Wiley‐Liss, Inc.
In vivo cellular imaging of lymphocyte trafficking by MRI: A tumor model approach to cell‐based anticancer therapy
Authors: Smirnov Pierre , Lavergne Elise , Gazeau Florence , Lewin Maïté , Boissonnas Alexandre , Doan Bich‐Thuy , Gillet Brigitte , Combadière Christophe , Combadière Béhazine , Clément Olivier 
Published: August 2006

AbstractThe aim of this study was to demonstrate the feasibility of in vivo cell tracking to monitor anticancer cell therapy by means of a high‐resolution noninvasive MRI method. Ovalbumin‐specific splenocytes (OT‐1) labeled with anionic γ‐Fe2O3 superparamagnetic iron oxide (SPIO) nanoparticles were adoptively transferred into C57BL/6 mice with growing ovalbumin‐expressing tumors. OT‐1 cells were tracked in vivo by 7 T MRI 24, 48, and 72 hr after they were injected. The results showed significant negative enhancement of the spleen at 24 hr, and of the tumor at 48 and 72 hr, after labeled cell injection. This suggests that the lymphocytes initially homed toward the spleen and were then recruited by the tumor. The presence of labeled cells was confirmed in ex vivo by 9.4 T microimaging of tumors and magnetic sorting of spleen cells. These results confirm that MR tracking of lymphocytes is feasible in vivo. This high‐resolution imaging method could be used to improve the monitoring of immune cell therapy. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
x‐f choice: Reconstruction of undersampled dynamic MRI by data‐driven alias rejection applied to contrast‐enhanced angiography
Authors: Malik Shaihan J. , Schmitz Stephan , O'Regan Declan , Larkman David J. , Hajnal Joseph V. 
Published: August 2006

AbstractA technique for reconstructing dynamic undersampled MRI data, termed “x‐f choice,” was developed and applied to dynamic contrast‐enhanced MR angiography (DCE‐MRA). Regular undersampling in k‐t space (a hybrid of k‐space and time) creates aliasing in the conjugate x‐f space that must be resolved. When regions in the object containing fast dynamic change are sparse, as in DCE‐MRA, signal overlap caused by aliasing is often much less than the undersample factor would imply. x‐f Choice reconstruction identifies overlapping signals using a model of the full non‐aliased x‐f space that is automatically generated from the undersampled data, and applies parallel imaging (PI) to separate them. No extra reference scans are required to generate either the model or the coil sensitivity maps. At each location in the reconstructed images, g‐factor noise amplification is compared with predicted reconstruction errors to obtain an optimized solution. Acceleration factors greater than the number of receiver coils are possible, but are limited by the sparseness of the dynamic content and the signal‐to‐noise ratio (SNR) (in DCE‐MRA the latter is dominant). Temporal fidelity was validated for up to a factor 10 speed‐up using retrospectively undersampled data from a six‐coil array. The method was tested on volunteers using fivefold prospective undersampling. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Transrectal ultrasound‐guided biopsy of prostate voxels identified as suspicious of malignancy on three‐dimensional 1H MR spectroscopic imaging in patients with abnormal digital rectal examination or raised prostate specific antigen level of 4–10 ng/ml
Authors: Kumar Virendra , Jagannathan N.R. , Kumar Rajeev , Thulkar Sanjay , Gupta S. Dutta , Hemal A.K. , Gupta N.P. 
Published: August 2006

AbstractResults of the evaluation of transrectal ultrasound (TRUS) guided needle biopsy of voxels identified as suspicious of malignancy on magnetic resonance spectroscopic imaging (MRSI) in a large cohort of men (n = 83) with abnormal digital rectal examination (DRE) [prostate specific antigen (PSA) 0–4 ng/ml] or PSA less than 10 ng/ml, are reported. Three‐dimensional 1H MRSI was carried out at 1.5 T using a pelvic‐phased array coil in combination with an endorectal surface coil. Voxels were classified as suspicious of malignancy based on Cit/(Cho + Cr) metabolite ratio. TRUS‐guided biopsy of suspicious voxels was performed using the z‐ and x‐coordinates obtained from MR images and two to three cores were taken from the suspected site. A systematic sextant biopsy was also carried out. MRSI showed voxels suspicious of malignancy in 44 patients while biopsy revealed cancer in 11 patients (25%). Patients who were negative for malignancy on MRSI were also negative on biopsy. An overall sensitivity of 100%, specificity of 54%, negative predictive value of 100% and accuracy of 60% were obtained. The site of biopsy was confirmed (n = 20) as a hypo‐intense area on repeat MRI while repeat MRSI revealed high choline and low citrate. The overall success rate of MRI‐directed TRUS‐guided biopsy of 25% was higher compared with a 9% success rate achieved without MR guidance in another group of 120 patients. Our results indicate that TRUS‐guided biopsy of suspicious area identified as malignant from MRSI can be performed using the coordinates of the voxel derived from MR images. This increases the detection rate of prostate cancer in men with PSA level <10 ng/ml or abnormal DRE and also demonstrates the potential of MR in routine clinical practice. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and properties of new aromatic poly(ester‐imide)s derived from 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl) pyridine and various dihydroxy compounds
Authors: Behniafar Hossein , Khaje Mirzai Ali Akbar , Saeed Ali Beit 
Published: August 2006

AbstractA novel class of wholly aromatic poly(ester‐imide)s, having a biphenylene pendant group, with inherent viscosities of 0.32–0.49 dL g−1 was prepared by the diphenylchlorophosphate‐activated direct polyesterification of the preformed imide‐ring‐containing diacid, 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine (1) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A reference diacid, 2,6‐bis(trimellitimido)pyridine (2) without a biphenylene pendant group and two phenylene rings in the backbone, was also synthesized for comparison purposes. At first, with due attention to structural similarity and to compare the characterization data, a model compound (3) was synthesized by the reaction of compound 1 with two mole equivalents of phenol. Moreover, the optimum condition of polymerization reactions was obtained via a study of the model compound synthesis. All of the resulting polymers were characterized by Fourier transform infrared and 1H NMR spectroscopy and elemental analysis. The ultraviolet λmax values of the poly(ester‐imide)s were also determined. All of the resulting polymers exhibited excellent solubility in common organic solvents, such as pyridine, chloroform, tetrahydrofuran, and m‐cresol, as well as in polar organic solvents, such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide. The crystalline nature of the polymers obtained was evaluated by means of wide‐angle X‐ray diffraction. The resulting poly(ester‐imide)s showed nearly an amorphous nature, except poly(ester‐imide) derived from 4,4′‐dihydroxy biphenyl. The glass transition temperatures (Tg) of the polymers determined by differential scanning calorimetry thermograms were in the range 298–342 °C. The 10% weight loss temperatures (T10%) from thermogravimetric analysis curves were found to be in the range 433–471 °C in nitrogen. Films of the polymers were also prepared by casting the solutions. Copyright © 2006 Society of Chemical Industry
Crystal structure of GlcAT‐S, a human glucuronyltransferase, involved in the biosynthesis of the HNK‐1 carbohydrate epitope
Authors: Shiba Tomoo , Kakuda Shinako , Ishiguro Masaji , Morita Ippei , Oka Shogo , Kawasaki Toshisuke , Wakatsuki Soichi , Kato Ryuichi 
Published: August 2006

AbstractThe HNK‐1 carbohydrate epitope is found in various neural cell adhesion molecules. Two glucuronyltransferases (GlcAT‐P and GlcAT‐S) are involved in the biosynthesis of HNK‐1 carbohydrate. Our previous study on the crystal structure of GlcAT‐P revealed the reaction and substrate recognition mechanisms of this enzyme. Comparative analyses of the enzymatic activities of GlcAT‐S and GlcAT‐P showed that there are notable differences in the acceptor substrate specificities of these enzymes. To elucidate differences between their specificities, we now solved the crystal structure of GlcAT‐S. Residues interacting with UDP molecule, which is a part of the donor substrate, are highly conserved between GlcAT‐P and GlcAT‐S. On the other hand, there are some differences between these proteins in the manner they recognize their respective acceptor substrates. Phe245, one of the most important GlcAT‐P residues for the recognition of acceptors, is a tryptophan in GlcAT‐S. In addition, Val320, which is located on the C‐terminal long loop of the neighboring molecule in the dimer and critical in the recognition of the acceptor sugar molecule by the GlcAT‐P dimer, is an alanine in GlcAT‐S. These differences play key roles in establishing the distinct specificity for the acceptor substrate by GlcAT‐S, which is further supported by site‐directed mutagenesis of GlcAT‐S and a computer‐aided model building of GlcAT‐S/substrate complexes. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Structure and magnetic properties of metastable Co–Cu solid solution nanowire arrays fabricated by electrodeposition
Authors: Wang Tao , Li Fashen , Wang Ying , Song Lijing 
Published: August 2006

AbstractNanowire arrays of the metastable Cox Cu1–x (0.20 ≤ x ≤ 0.85) solid solution system which can not be obtained by equilibrium methods, were prepared by electrodeposition in pores of anodic aluminum oxide (AAO) template, and subsequently annealed at different temperatures. The as‐deposited samples all show single phase of fcc structure, and lattice parameters decrease with the increase of Co content and fundamentally accord with Vegard's law. The phase transition with heat treatment was investigated by X‐ray diffraction and differential thermal analysis (DTA) which further confirmed the formation of solid solution. With Co content increasing, the coercivity along nanowire axis for as‐deposited samples increases, but it decreases for the annealed samples at 700 °C. This phenomenon was explained considering the interaction of Co particles through Cu in nanowires after phase separation. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical characterization of polyethylene and cobalt phthalocyanine ultrathin films by means of the ATR technique at surface plasmon resonance
Authors: Rodríguez Juárez M. , Muñoz Aguirre N. , Martínez Pérez L. , Garibay‐Febles V. , Lozada‐Cassou M. , Becerril M. , Angel O. Zelaya 
Published: August 2006

AbstractIt is well known that the development and determination of optical properties of ultrathin films is an important issue in many technological areas. In this work organic polyethylene (PE) and cobalt phthalocyanines (CoPc) ultrathin films were deposited over metal films using the r.f. sputtering and thermal evaporation techniques, respectively. Attenuated total reflection (ATR) measurements for the system organic film/metal at the surface plasmon resonance (SPR) were used for determining the thicknesses and optical properties of the PE and CoPc thin films. Thicknesses of the order of some nanometers were found, fitting the theoretical multilayer ATR model, for p polarization monochromatic light, to the experimental reflection data. The dielectric function of CoPc ultrathin films was determined at a wavelength of 632.8 nm. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic characteristics of Mn–Co–Ti substituted barium ferrite synthesized by sol–gel processing
Authors: Ghasemi A. , Saatchi A. , Salehi M. , Hossienpour A. , Morisako A. , Liu X. 
Published: August 2006

AbstractBaFe12–x (Mn0.5Co0.5Ti)x /2O19 hexaferrites with x = 1, 2 and 3 were prepared by a sol–gel process. The reaction temperature was much lower than that of the conventional ceramic method. The ferrite powders possess a hexagonal shape and are well separated from one another. Thermogravimetric analysis, X‐ray diffraction, a scanning electron microscope, an ac susceptometer and a vibrating sample magnetometer were used to analyze their structures and magnetic properties. The results showed that for all the samples magnetoplumbite structures have been formed. The samples with x = 2 and 3 have higher magnetic susceptibility and larger coercive force. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rapid crystallization of WS2 films assisted by a thin nickel layer: An in situ energy‐dispersive X‐ray diffraction study
Authors: Ellmer K. , Seeger S. , Mientus R. 
Published: August 2006

AbstractBy rapid thermal crystallization of an amorphous WS3+x film, deposited by reactive magnetron sputtering at temperatures below 150 °C, layer‐type semiconducting tungsten disulfide films (WS2) were grown. The rapid crystallization was monitored in real‐time by in situ energy‐dispersive X‐ray diffraction. The films crystallize very fast (>40 nm/s), provided that a thin nickel film acts as nucleation seeds. Experiments on different substrates and the onset of the crystallization only at a temperature between 600 and 700 °C points to the decisive role of seeds for the textured growth of WS2, most probably liquid NiSx drops. The rapidly crystallized WS2 films exhibit a pronounced (001) texture with the van der Waals planes oriented parallel to the surface, leading to photoactive layers with a high hole mobility of about 80 cm2/Vs making such films suitable as absorbers for thin film solar cells. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hot phonons in GaN channels for HEMTs
Authors: Matulionis A. 
Published: August 2006

AbstractAccumulation of non‐equilibrium longitudinal optical (LO) phonons (termed hot phonons) is considered as a possible cause for limitation of hot‐electron drift velocity at high electric fields in a GaN biased channel with a two‐dimensional electron gas (2DEG). Equivalent hot‐phonon temperature and hot‐phonon lifetime are estimated from experimental results on hot‐electron noise at a microwave frequency. Dependence of the hot‐phonon parameters on electron density and channel composition is investigated, and frequency performance of high‐electron‐mobility transistors (HEMTs) is discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solid‐Phase Synthesis of Aryl‐Alkylamine Derivatives Using Protected Aminoalcohol Building Blocks on SynPhaseTM Lanterns
Authors: Zajdel Pawel , Subra Gilles , Pawłowski Maciej , Martinez Jean 
Published: August 2006

AbstractA series of aryl‐alkylamine carboxamide and sulfonamide derivatives were synthesized on a BAL linker using SynPhaseTM Lanterns. All the reaction steps were performed on a solid support. The key stage was on‐resin substitution of TBDPSi‐protected aminoalcohols with various amines, which circumvented the multistep solution‐phase synthesis of alkylamine building blocks. The chemistry applied allows building up focused libraries targeted on CNS receptors.
Synthesis of Fluorous‐FMOC Reagents and Purification of Protected Dipeptides with Fluorous Solid Phase Extraction
Authors: Matsugi Masato , Yamanaka Kunihiro , Inomata Issei , Takekoshi Nao , Hasegawa Masakazu , Curran Dennis P. 
Published: August 2006

AbstractFluorous‐FMOC (f‐FMOC) reagents bearing C4F9 or C6F13 chains were prepared and the f‐FMOC protection for amino acid was conducted. Following peptide coupling, the resulting fluorous dipeptides were separated from the non‐fluorous by‐products effectively by using fluorous solid phase extraction.
Analysis of self‐interaction correction for describing core excited states
Authors: Imamura Yutaka , Nakai Hiromi 
Published: August 2006

AbstractCore‐excitation energies are calculated by the self‐interaction‐corrected time‐dependent density functional theory (SIC‐TDDFT) and SIC‐delta‐self‐consistent field (SIC‐ΔSCF) methods. For carbon monoxide, SIC‐TDDFT severely overestimates core‐excitation energies, while the SIC‐ΔSCF method using Kohn–Sham density functional theory (KS‐DFT) slightly overestimates. These behaviors are attributed to the fact that the self‐interaction errors in the total and orbital energies considerably differ. We evaluate the difference of the self‐interaction errors for the Slater exchange functional. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007