bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tris(hydroxymethyl)aminomethane‐functionalized silica particles and their application for hydrophilic interaction chromatography
Authors: Bui Nhat Thi Hong , Verhage Jeroen J. , Irgum Knut 
Published: September 2010

AbstractA new method is presented for synthesizing a highly hydrophilic silica‐based material for use in hydrophilic interaction chromatography. Porous silica particles used as a starting substrate were modified with 3‐bromopropyl trichlorosilane and grafted with glycidyl methacrylate by controlled (“living”) atom transfer radical polymerization in order to introduce an oxirane‐carrying reactive tentacle layer on the silica surface. The grafted material was thereafter subject to an oxirane ring opening reaction with tris(hydroxy‐methyl)aminomethane in dimethylformamide to yield a polymer‐bound equivalent of the well known and highly hydrophilic “TRIS” buffering substance. Chemical characterization was done by diffuse reflectance FT‐IR, X‐ray photoelectron spectroscopy, elemental analysis, and 1H NMR. Porosity and surface area examination was done with Brunauer–Emmett–Teller. Chromatographic application of the material was evaluated by separations of nucleic bases, small organic acids, and common nucleotides under mixed hydrophilic interaction chromatography and weak anion exchange conditions.
Sol–gel microextraction phases for sample preconcentration in chromatographic analysis
Authors: Segro Scott S. , Tran MinhPhuong , Kesani Sheshanka , Alhendal Abdullah , Turner Erica B. , Abdul Malik  
Published: September 2010

AbstractSol–gel technology provides a simple and reliable method for solid‐phase microextraction (SPME) fiber preparation through in situ creation of surface‐bonded organic–inorganic hybrid coatings characterized by enhanced thermal stability and solvent‐resistance properties that are important for the coupling of SPME with GC and HPLC, respectively. The sol–gel coating technology has led to the development of an extensive array of sol–gel sorbent coatings for SPME. In this article, sol–gel microextraction coatings are reviewed, with particular attention on their synthesis, characterization, and applications in conjunction with GC and HPLC analyses. In addition, the development of sol–gel‐coated stir bars, their inherent advantages, and applications are discussed. Next, the development and applications of sol–gel capillary microextraction (CME) in hyphenation with GC and HPLC is extensively reviewed. The newly emerging germania‐ and titania‐based sol–gel microextraction phases look promising, especially in terms of pH and hot solvent stability. Finally, sol–gel monolithic beds for CME are reviewed. Such monolithic beds are in a position to greatly improve the extracting capabilities and enhanced sensitivity in CME.
Impact of polyurea structure on grease properties
Authors: Liu L. , Sun H. W. 
Published: September 2010

AbstractThe thickener structure of polyurea grease has a crucial effect on its properties. Therefore, it is very important to study the relationship between a thickener structure and physical and performance properties. In this study, polyurea greases were synthesised, having a different number of urea groups in per polyurea thickener molecule. Properties such as dropping point, penetration, oil separation, shear stability and four‐ball wear and extreme pressure (EP) were evaluated. The result shows that properties of polyurea grease vary with the number of urea group per polyurea molecule. Based on molecular theory, the mechanisms explaining these effects are briefly discussed. Copyright © 2010 John Wiley & Sons, Ltd.
Estimation of the optimal wavelengths for laser‐induced wound healing
Authors: Ankri Rinat , Lubart Rachel , Taitelbaum Haim 
Published: September 2010

AbstractBackground and objectivesAccording to earlier in vitro low level laser therapy (LLLT) studies, wavelengths in the red and near infrared range, that are absorbed by cytochrome oxidase, stimulate cell growth and hence wound healing. Wavelengths in the blue region that are absorbed by flavins were found to exert a bactericidal effect that is very important for treating infected wounds. However, as far as therapeutic application of light is concerned, penetration into the tissue must be considered. For this purpose we estimated the penetration depth as a function of the relevant wavelengths, using the formulae of the photon migration model for skin tissue.MethodsWe use the photon diffusion model, which is an analytical model for describing light transfer in biological tissues. We refer to the most common chromophores in human tissue and evaluate their volume fraction and concentration in skin cells. These empirically estimated mean wavelength‐dependent absorption coefficients are then substituted in the theoretical expressions for the optical penetration depth in the tissue. The wavelengths, for which the penetration depth is the highest, are the optimal wavelengths to be used in wound healing treatments.ResultsOur model suggests that the optimal wavelengths for therapeutic treatments are in the red region with a local maximum at 730 nm. As to the blue region, a local maximum at 480 nm was found.ConclusionLight at 480 nm should be used for treating infected wounds followed by 730 nm light for enhancing wound closure. Lasers Surg. Med. 42:760–764, 2010 © 2010 Wiley‐Liss, Inc.
119/117/115Sn low‐abundance single‐transition correlation spectroscopy (LASSY): sensitivity‐enhanced homonuclear correlation experiments for Sn NMR
Authors: George Christy , Chandrakumar Narayanan 
Published: September 2010

AbstractWe report the implementation of our novel rare‐spin homonuclear correlation experiment, namely, Low‐Abundance Single‐transition correlation SpectroscopY (LASSY), for 119/117/115Sn NMR at natural abundance. Our pulse sequence results in diagonal suppressed COSY‐style display and outperforms the optimal homonuclear correlation experiment for rare spins, which involves double quantum evolution (INADEQUATE CR). The new experiment maximizes efficiency both in respect of pulse transformations as well as relaxation effects, and gives rise to a simplified two‐dimensional (2D) spectrum with considerably reduced crowding, exhibiting only one transition in each cross peak, instead of four. Performance optimization of LASSY is carried out in light of the relatively ‘large’ line widths typical of Sn NMR in solution state. The superior performance of the sequence is demonstrated on dimeric tetraorganodistannoxane samples. Copyright © 2010 John Wiley & Sons, Ltd.
The effects of spatial sampling choices on MR temperature measurements
Authors: Todd Nick , Vyas Urvi , de Bever Josh , Payne Allison , Parker Dennis L. 
Published: September 2010

AbstractThe purpose of this article is to quantify the effects that spatial sampling parameters have on the accuracy of magnetic resonance temperature measurements during high intensity focused ultrasound treatments. Spatial resolution and position of the sampling grid were considered using experimental and simulated data for two different types of high intensity focused ultrasound heating trajectories (a single point and a 4‐mm circle) with maximum measured temperature and thermal dose volume as the metrics. It is demonstrated that measurement accuracy is related to the curvature of the temperature distribution, where regions with larger spatial second derivatives require higher resolution. The location of the sampling grid relative temperature distribution has a significant effect on the measured values. When imaging at 1.0 × 1.0 × 3.0 mm3 resolution, the measured values for maximum temperature and volume dosed to 240 cumulative equivalent minutes (CEM) or greater varied by 17% and 33%, respectively, for the single‐point heating case, and by 5% and 18%, respectively, for the 4‐mm circle heating case. Accurate measurement of the maximum temperature required imaging at 1.0 × 1.0 × 3.0 mm3 resolution for the single‐point heating case and 2.0 × 2.0 × 5.0 mm3 resolution for the 4‐mm circle heating case. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.
Nontriggered MRI quantification of aortic pulse‐wave velocity
Authors: Langham Michael C. , Li Cheng , Magland Jeremy F. , Wehrli Felix W. 
Published: September 2010

AbstractPulse‐wave velocity is an index of arterial stiffness, which is a strong indicator of cardiovascular risk. We present a high‐speed technique that generates time‐resolved complex difference signal intensity simultaneously in the ascending and descending aorta from velocity‐encoded projections without gating, allowing quantification of pulse‐wave velocity. The velocity‐time curve was approximated with a time‐resolved complex difference signal intensity to estimate the propagation time of the pulse wave in the aortic arch. The path length of the pulse wave is measured from an oblique sagittal image in a plane encompassing thoracic ascending and descending aorta, and pulse‐wave velocity is computed from the ratio between the path length and pulse‐wave propagation time. The method was implemented at 1.5 T and 3 T, and pulse‐wave velocity was quantified in healthy subjects (ages 20–70 years, N = 23) without symptoms or prior history of cardiovascular events. In addition, the method was compared against retrospectively EKG‐gated PC‐MRI. The overall results were found to be in good agreement with literature data showing age‐related increase in aortic stiffness. The RMS differences between the projection and gated PC‐MRI methods were less than 4%. Key benefits of the proposed method are simplicity in both data acquisition and processing requiring only computation of the complex difference between the velocity‐encoded projections rather than absolute velocity. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.
Reference values for the nocturnal bladder capacity index
Authors: Burton Claire , Weiss Jeffrey P. , Parsons Matthew , Blaivas Jerry G. , Coats Alfred C. 
Published: September 2010

AbstractAimsThe Nocturnal Bladder Capacity Index (NBCi) has been reported to be useful in distinguishing between nocturia caused by low bladder capacity and nocturnal polyuria. This paper aims to calculate reference values for NBCi from an asymptomatic population by comparing these with NBCi values from patients with lower urinary tract symptoms (LUTS) to obtain an indication of the sensitivity with which the NBCi detects low nocturnal bladder capacity. This paper also compares the sensitivity of rounded and unrounded calculations of NBCi.MethodsComputer processed 3‐day bladder diaries from 253 asymptomatic volunteers and 184 female patients with LUTS were analyzed. NBCi values were calculated from each diary using rounded and unrounded formulae. 90th and 95th centile NBCi cutoff values were obtained from frequency distributions.ResultsNBCi reference values from the asymptomatic group were 1.1 (unrounded) and 0.7 (rounded) for 90th centile, and 1.3 (unrounded) and 1.0 (rounded) for 95th centile. The use of the rounded formula gave identical NBCi values despite a large variation in Vn/Vmax ratios whereas unrounded NBCis varied continuously with Vn/Vmax ratios. The unrounded formula found significantly more elevated NBCis in the patient group.ConclusionWe suggest that an unrounded NBCi of 1.3 be considered a cutoff point above which reduced nocturnal bladder capacity should be investigated as a cause of nocturia. Rounding the NBCi lead to an underestimation of elevated values in a population of female patients with LUTS. Neurourol. Urodynam. 30:52–57, 2011. © 2010 Wiley‐Liss, Inc.
Twenty‐five pitfalls in the analysis of diffusion MRI data
Authors: Jones Derek K. , Cercignani Mara 
Published: September 2010

AbstractObtaining reliable data and drawing meaningful and robust inferences from diffusion MRI can be challenging and is subject to many pitfalls. The process of quantifying diffusion indices and eventually comparing them between groups of subjects and/or correlating them with other parameters starts at the acquisition of the raw data, followed by a long pipeline of image processing steps. Each one of these steps is susceptible to sources of bias, which may not only limit the accuracy and precision, but can lead to substantial errors. This article provides a detailed review of the steps along the analysis pipeline and their associated pitfalls. These are grouped into 1 pre‐processing of data; 2 estimation of the tensor; 3 derivation of voxelwise quantitative parameters; 4 strategies for extracting quantitative parameters; and finally 5 intra‐subject and inter‐subject comparison, including region of interest, histogram, tract‐specific and voxel‐based analyses. The article covers important aspects of diffusion MRI analysis, such as motion correction, susceptibility and eddy current distortion correction, model fitting, region of interest placement, histogram and voxel‐based analysis. We have assembled 25 pitfalls (several previously unreported) into a single article, which should serve as a useful reference for those embarking on new diffusion MRI‐based studies, and as a check for those who may already be running studies but may have overlooked some important confounds. While some of these problems are well known to diffusion experts, they might not be to other researchers wishing to undertake a clinical study based on diffusion MRI. Copyright © 2010 John Wiley & Sons, Ltd.
Mapping brain anatomical connectivity using white matter tractography
Authors: Lazar Mariana 
Published: September 2010

AbstractIntegration of the neural processes in the human brain is realized through interconnections that exist between different neural centers. These interconnections take place through white matter pathways. White matter tractography is currently the only available technique for the reconstruction of the anatomical connectivity in the human brain noninvasively andin vivo. The trajectory and terminations of white matter pathways are estimated from local orientations of nerve bundles. These orientations are obtained using measurements of water diffusion in the brain. In this article, the techniques for estimating fiber directions from diffusion measurements in the human brain are reviewed. Methods of white matter tractography are described, together with the current limitations of the technique, including sensitivity to image noise and partial voluming. The applications of white matter tractography to the topographical characterization of the white matter connections and the segmentation of specific white matter pathways, and corresponding functional units of gray matter, are discussed. In this context, the potential impact of white matter tractography in mapping the functional systems and subsystems in the human brain, and their interrelations, is described. Finally, the applications of white matter tractography to the study of brain disorders, including fiber tract localization in brains affected by tumors and the identification of impaired connectivity routes in neurologic and neuropsychiatric diseases, are discussed. Copyright © 2010 John Wiley & Sons, Ltd.
Effective medium theory of a diffusion‐weighted signal
Authors: Novikov Dmitry S. , Kiselev Valerij G. 
Published: September 2010

AbstractLiving tissues and other heterogeneous media generally consist of structural units with different diffusion coefficients and NMR properties. These blocks, such as cells or clusters of cells, can be much smaller than the imaging voxel, and are often comparable with the diffusion length. We have developed a general approach to quantify the medium heterogeneity when it is much finer than the sample size or the imaging resolution. The approach is based on the treatment of the medium statistically in terms of the correlation functions of the local parameters. The diffusion‐weighted signal is explicity found for the case in which the local diffusivity varies in space, in the lowest order in the diffusivity variance. We demonstrate how the correlation length and the variance of the local diffusivity contribute to the time‐dependent diffusion coefficient and the time‐dependent kurtosis. Our results are corroborated by Monte Carlo simulations of diffusion in a two‐dimensional heterogeneous medium. Copyright © 2010 John Wiley & Sons, Ltd.
An adaptive, multilevel scheme for the implicit solution of three‐dimensional phase‐field equations
Authors: Green J.R. , Jimack P.K. , Mullis A.M. , Rosam J. 
Published: September 2010

AbstractPhase‐field models, consisting of a set of highly nonlinear coupled parabolic partial differential equations, are widely used for the simulation of a range of solidification phenomena. This article focuses on the numerical solution of one such model, representing anisotropic solidification in three space dimensions. The main contribution of the work is to propose a solution strategy that combines hierarchical mesh adaptivity with implicit time integration and the use of a nonlinear multigrid solver at each step. This strategy is implemented in a general software framework that permits parallel computation in a natural manner. Results are presented that provide both qualitative and quantitative justifications for these choices.© 2010 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010
The approximation of planar curve evolutions by stable fully implicit finite element schemes that equidistribute
Authors: Barrett John W. , Garcke Harald , Nürnberg Robert 
Published: September 2010

AbstractOn the basis of our previous work, we introduce novel fully discrete, fully practical parametric finite element approximations for geometric evolution equations of curves in the plane. The fully implicit approximations are unconditionally stable and intrinsically equidistribute the vertices at each time level. We present iterative solution methods for the systems of nonlinear equations arising at each time level and present several numerical results. The ideas easily generalize to the evolution of curve networks and to anisotropic surface energies. © 2010 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010
The challenges and opportunities of implementing the integrity pact as a strategy for combating corruption in Nigeria's oil rich Niger Delta region
Authors: Idemudia Uwafiokun , Cragg Wesley , Best Bronwyn 
Published: September 2010

AbstractIn recent years, significant local and transnational concerted initiatives have been instituted to curb the incidence of corruption that has undermined socio‐economic development in Nigeria. Drawing on the critiques of such initiatives, and the experience from the process of implementing the Integrity Pact in the Niger Delta Development Commission, this article suggests that the Integrity Pact in principle offers real opportunities that can both reinforce and complement existing anti‐corruption initiatives in Nigeria's public sector. However, political instability, lack of continuity in civil service leadership and limited capacity are core challenges that confront the successful implementation and institutionalisation of the Integrity Pact as a means of fighting corruption and meeting sustainable development objectives in the Niger Delta. The article concludes by considering the implications of the findings for the fight against corruption in Nigeria. Copyright © 2010 John Wiley & Sons, Ltd.
KRAS and BRAF: drug targets and predictive biomarkers
Authors: Vakiani Efsevia , Solit David B 
Published: September 2010

AbstractThree decades have passed since RAS was first identified as the transformative factor in the Harvey and Kirsten strains of the mouse sarcoma virus. RAS and several of its downstream effectors, including BRAF, have since been shown to be commonly mutated in broad range of human cancers and biological studies have confirmed that RAS pathway activation promotes tumour initiation, progression and metastatic spread in many contexts. With the identification of RAS mutation as a strong predictor of clinical resistance to EGFR‐targeted therapies, RAS mutational testing has been incorporated into the routine clinical care of patients with colorectal and lung cancers. This article reviews the current understanding of RAS signalling as it relates to cancer biology, current efforts to develop inhibitors of RAS and its key downstream effectors and the technical challenges of RAS mutational testing in the clinical setting. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Improving adhesion of acrylic waterborne PSAs to low surface energy materials: Introduction of stearyl acrylate
Authors: Agirre Amaia , Nase Julia , Degrandi Elise , Creton Costantino , Asua José M. 
Published: September 2010

AbstractThe effect of incorporating stearyl acrylate (SA) in the polymer backbone of a pressure sensitive adhesive on its adhesion properties on low energy surfaces was investigated. The presence of SA did not affect the polymer microstructure (sol molecular weight, gel, and network density) but affected the compatibility with the low energy substrate and the elasticity of the adhesive. The combination of these effects resulted in an optimum SA content. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Universal xanthate‐mediated controlled free radical polymerizations of the “less activated” vinyl monomers
Authors: Yan Yuefang , Zhang Wei , Qiu Yansheng , Zhang Zhengbiao , Zhu Jian , Cheng Zhenping , Zhang Weidong , Zhu Xiulin 
Published: September 2010

AbstractThe living free radical polymerizations of three “less activated” monomers (LAMs), vinyl acetate, N‐vinylcarbazole, and N‐vinylpyrrolidone, were successfully achieved in the presence of a disulfide, isopropylxanthic disulfide (DIP), using 2,2′‐azoisobutyronitrile (AIBN) as the initiator. The living behaviors of polymerizations of LAMs are evidenced by first‐order kinetic plots and linear increase of molecular weights (Mns) of the polymers with monomer conversions, while keeping the relatively low molecular weight distributions, respectively. The effects of reaction temperatures and molar ratios of components on the polymerization were also investigated in detail. The polymerization proceeded with macromolecular design via interchange of xanthate process, where xanthate formed in situ from reaction of AIBN and DIP. The architectures of the polymers obtained were characterized by GPC, 1H NMR, UV–vis, and MALDI‐TOF‐MS spectra, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Structurally distinct toxicity inhibitors bind at common loci on β‐amyloid fibril
Authors: Keshet Ben , Gray Jeffrey J. , Good Theresa A. 
Published: September 2010

AbstractThe accumulation of aggregated β‐Amyloid (Aβ) in the brain is a hallmark of Alzheimer's disease and is thought to play a role in the neurotoxicity associated with the disease. The mechanism by which Aβ aggregates induce toxicity is uncertain. Nonetheless, several small molecules have been found to interact with Aβ fibrils and to prevent their toxicity. In this paper we studied the binding of these known toxicity inhibitors to Aβ fibrils, as a means to explore surfaces or loci on Aβ aggregates that may be significant in the mechanism of action of these inhibitors. We believe knowledge of these binding loci will provide insight into surfaces on the Aβ fibrils important in Aβ biological activity. The program DOCK was used to computationally dock the inhibitors to an Aβ fibril. The inhibitors docked at two shared binding loci, near Lys28 and at the C‐termini near Asn27 and Val39. The docking predictions were experimentally verified using lysine specific chemical modifications and Aβ fibrils mutated at Asn27. We found that both Congo red and Myricetin, despite being structurally different, bound at the same two sites. Additionally, our data suggests that three additional Aβ toxicity inhibitors may also bind in one of the sites. Identification of these common binding loci provides targets on the Aβ fibril surface that can be tested in the future for their role in Aβ biological activity.