bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of phase separation in alcohol/water mixtures using two‐body force field and standard molecular dynamics
Authors: Ferrari E. S. , Burton R. C. , Davey R. J. , Gavezzotti A. 
Published: June 2006

AbstractStandard molecular dynamics simulations have been carried out on pure alcohols and alcohol/water mixtures. A simple atom–atom force field consisting of Lennard–Jones potentials plus coulombic terms over atomic point charges, but without explicit polarization terms, has been specifically fitted to reproduce several experimental properties of the pure alcohols, and has been used for mixtures by developing combination rules with the TIP3P water model. Densities, enthalpies of vaporization, radial distribution functions, self‐diffusion coefficients, and rotational correlation functions of the pure alcohols are well reproduced and compare favorably with those from more sophisticated force fields. Some key aspects of the phase behaviour are correctly reproduced by the molecular dynamics simulation, showing a distinct demixing process for the n‐butanol/water mixture as opposed to the stability of the t‐butanol/water mixtures. The results demonstrate the ability of a molecular dynamics simulation, even in its standard form and with easily accessible time ranges, but with a carefully optimized force field, to simulate and, to a certain extent, predict the properties of binary mixtures. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 1211–1219, 2006
Virtual biopsy of the joint tissues using near‐infrared, reflectance confocal microscopy. A pilot study
Authors: Campo‐Ruiz Vanessa , Patel Dinesh , Anderson R. Rox , Delgado‐Baeza Emilio , González Salvador 
Published: June 2006

AbstractStandard noninvasive imaging techniques applied to joints provide gross morphological features, insufficient for assessing histological detail. On the other hand, biopsying is invasive, time consuming, and may involve unwanted processing artifacts. Near‐infrared reflectance confocal microscopy is a technique that allows serial, high‐resolution optical sectioning through intact tissues without employing exogenous fluorescent stains. The aim of this work was to evaluate the potential utility of near‐infrared reflectance confocal microscopy for providing immediate histological information on meniscus, articular cartilage, epiphyseal plate, bone, muscle, and tendon. Images from near‐infrared reflectance confocal microscopy were compared with mirror routine histology sections. Characteristic architectural features were readily visualized in the three dimensions of space. Additionally, the use of experimental contrast agents highlighted the localization of nuclei. Limitations include penetration depth and minor optical artifacts. In conclusion, near‐infrared reflectance confocal microscopy is a useful technique for immediate, nondestructive, serial “virtual” sectioning through intact tissues, being thus a potential adjunct to current imaging techniques in orthopedics. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Rank‐tolerance graph classes
Authors: Golumbic Martin Charles , Jamison Robert E. 
Published: June 2006

AbstractIn this article we introduce certain classes of graphs that generalize
ϕ‐tolerance chain graphs. In a rank‐tolerance representation of a graph, each vertex is assigned two parameters: a rank, which represents the size of that vertex, and a tolerance which represents an allowed extent of conflict with other vertices. Two vertices are adjacent if and only if their joint rank exceeds (or equals) their joint tolerance. This article is concerned with investigating the graph classes that arise from a variety of functions, such as min, max, sum, and prod (product), that may be used as the coupling functions ϕ and ρ to define the joint tolerance and the joint rank. Our goal is to obtain basic properties of the graph classes from basic properties of the coupling functions.We prove a skew symmetry result that when either ϕ or ρ is continuous and weakly increasing, the (ϕ,ρ)‐representable graphs equal the complements of the (ρ,ϕ)‐representable graphs. In the case where either ϕ or ρ is Archimedean or dual Archimedean, the class contains all threshold graphs. We also show that, for min, max, sum, prod (product) and, in fact, for any piecewise polynomial ϕ, there are infinitely many split graphs which fail to be representable.In the reflexive case (where ϕ = ρ), we show that if ϕ is nondecreasing, weakly increasing and associative, the class obtained is precisely the threshold graphs. This extends a result of Jacobson, McMorris, and Mulder [10] for the function min to a much wider class, including max, sum, and prod.We also give results for homogeneous functions, powers of sums, and linear combinations of min and max. © 2006 Wiley Periodicals, Inc. J Graph Theory
The generalized acyclic edge chromatic number of random regular graphs
Authors: Gerke Stefanie , Greenhill Catherine , Wormald Nicholas 
Published: June 2006

AbstractThe r‐acyclic edge chromatic number of a graph is defined to be the minimum number of colors required to produce an edge coloring of the graph such that adjacent edges receive different colors and every cycle C has at least min(|C|, r) colors. We show that (r − 2)d is asymptotically almost surely (a.a.s.) an upper bound on the r‐acyclic edge chromatic number of a random d‐regular graph, for all constants r ≥ 4 and d ≥ 2. © 2006 Wiley Periodicals, Inc. J Graph Theory 53: 101–125, 2006
Correlation between the bone marrow blood perfusion and lipid water content on the lumbar spine in female subjects
Authors: Chen Wei‐Tsung , Shih Tiffany Ting‐Fang 
Published: June 2006

AbstractPurposeTo assess the marrow lipid water ratio (LWR) and spectral line width (LW) of lumbar vertebra by proton MR spectroscopy (1H MRS) and correlate with the marrow blood perfusion (MBP) by contrast‐enhanced dynamic MRI (dMRI) in female subjects.Materials and MethodsA total of 50 female subjects were included. Single‐voxel 1H MRS was measured at the L3 vertebrae. In the dMRI study, the maximum enhancement percentage (Emax) and enhancement slope were calculated from time‐intensity curves. Pearson's correlation was calculated to explore the association of 1H MRS, age, and perfusion parameters. Partial correlation was then used to control confounder effect.ResultsLWR was negatively correlated with Emax (r = –0.72; P < 0.0001), but positively correlated with age (r = 0.63; P < 0.0001). Lipid LW was negatively correlated with age (r = –0.33; P <0.05), but positively correlated with Emax (r = 0.4; P < 0.05). After adjusting for the age effect by partial correlation, marrow LWR still negatively correlated with Emax (r = –0.63; P < 0.0001). After adjusting for the Emax effect, marrow LWR still positively correlated with age (r = 0.37; P < 0.05).ConclusionAfter controlling the age factor, the LWR and water LW has significant negative correlation with vertebral BMP. Further investigation is needed to explore the relationship between bone marrow fat metabolism and angiogenesis. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Passive catheter visualization in magnetic resonance–guided endovascular therapy using multicycle projection dephasers
Authors: Draper Jonathan N. , Lauzon M. Louis , Frayne Richard 
Published: June 2006

AbstractPurposeTo improve upon the conventional projection dephaser (PD) method of background suppression and evaluate the use of multicycle projection dephasers to improve catheter conspicuity in background‐suppressed MR images.Materials and MethodsPassive visualization of endovascular catheters in MR images is compared using two background suppression techniques: 1) the conventional PD method and 2) the multicycle PD method. Contrast‐filled 4‐French (1.3 mm) catheters were imaged in homogeneous and heterogeneous phantoms, and in the common carotid artery of a canine using a modified spoiled gradient echo imaging sequence. We used catheter‐to‐background contrast (ranging from –100% to 100%) as the metric to compare background suppression techniques.ResultsIn the homogeneous and heterogeneous phantoms, the contrast was –6.9% (catheter darker than background) and 15.0%, respectively, using the conventional PD method, and 50.6% and 44.0%, respectively, using the multicycle PD method. In the canine carotid artery, the contrast was –3.1% using the conventional PD method and 53.0% using the multicycle PD method.ConclusionThis work shows that multicycle projection dephasers improve catheter conspicuity over the conventional PD method. The multicycle PD method has potential for use in guiding endovascular procedures. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Discrepancy‐based adaptive regularization for GRAPPA reconstruction
Authors: Qu Peng , Wang Chunsheng , Shen Gary X. 
Published: June 2006

AbstractPurposeTo develop a novel regularization method for GRAPPA by which the regularization parameters can be optimally and adaptively chosen.Materials and MethodsIn the fit procedures in GRAPPA, the discrepancy principle, which chooses the regularization parameter based on a priori information about the noise level in the autocalibrating signals (ACS), is used with the truncated singular value decomposition (TSVD) regularization and the Tikhonov regularization, and its performance is compared with the singular value (SV) threshold method and the L‐curve method, respectively by axial and sagittal head imaging experiments.ResultsIn both axial and sagittal reconstructions, normal GRAPPA reconstruction results exhibit a relatively high level of noise. With discrepancy‐based choices of parameters, regularization can improve the signal‐to‐noise ratio (SNR) with only a very modest increase in aliasing artifacts. The L‐curve method in all of the reconstructions leads to overregularization, which causes severe residual aliasing artifacts. The 10% SV threshold method yields good overall image quality in the axial case, but in the sagittal case it also leads to an obvious increase in aliasing artifacts.ConclusionNeither a fixed SV threshold nor the L‐curve are robust means of choosing the appropriate parameters in GRAPPA reconstruction. However, with the discrepancy‐based parameter‐choice strategy, adaptively regularized GRAPPA can be used to automatically choose nearly optimal parameters for reconstruction and achieve an excellent compromise between SNR and artifacts. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Comparison between intravenous and intraarterial contrast injections for dynamic 3D MRI of liver tumors in the VX2 rabbit model
Authors: Larson Andrew C. , Rhee Thomas K. , Deng Jie , Wang Dingxin , Sato Kent T. , Salem Riad , Paunesku Tatjana , Woloschak Gayle , Mulcahy Mary F. , Li Debiao , Omary Reed A. 
Published: June 2006

AbstractPurposeTo test the hypothesis that catheter‐directed intraarterial (IA) contrast agent injection increases tumor enhancement and conspicuity compared to intravenous (IV) injection.Materials and MethodsEight VX2 liver tumors were grown in five rabbits. After positioning a catheter in the hepatic artery, we performed 3D inversion recovery GRE MRI after IA and IV gadopentetate‐dimeglumine contrast injections at doses of 0.04 and 0.1 mmol/kg, respectively. Peak enhancement (signal‐to‐noise ratio (SNR)) and conspicuity (contrast‐to‐noise ratio (CNR)) were measured for each acquisition.ResultsThe peak SNR and CNR were 21.7 ± 5.8 and 17.0 ± 4.8 (mean ± SD) after IA injection, and 16.9 ± 10.2 and 6.2 ± 2.6 after IV injection. The IA CNR was significantly greater than the IV CNR (P < 0.05), with a >60% increase in CNR for each tumor. For six of the eight tumors the IA SNR was greater than the IV SNR, but statistical significance was not achieved due to the small sample size of the study (P = 0.07).ConclusionWe demonstrated the feasibility of using IA injection techniques to improve tumor conspicuity. This strategy could be employed to enhance the detection of small liver tumors or to conserve contrast agent in future MRI‐guided transcatheter liver therapies. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Analytical and semipreparative high performance liquid chromatography separation of stereoisomers of novel 3,4‐dihydropyrimidin‐4(3H)‐one derivatives on the immobilised amylose‐based Chiralpak IA chiral stationary phase
Authors: Cirilli Roberto , Ferretti Rosella , Gallinella Bruno , La Torre Francesco , Mai Antonello , Rotili Dante 
Published: June 2006

AbstractDirect HPLC separation of stereoisomers of three novel 5‐methyl‐2‐(alkylthio)‐6‐(2,6‐difluorophenylalkyl)‐3,4‐dihydropyrimidin‐4(3H)‐ones endowed with antiviral and potential antiproliferative and morphological differentiation activity against melanoma cells was performed by using the new immobilised amylose‐based Chiralpak IA chiral stationary phase. Stereoselective conditions were achieved using normal phase eluents containing “non‐standard” solvents such as ethyl acetate, methyl tert‐butyl ether, or dichloromethane. In order to study the chiroptical properties of single stereoisomers, mg‐scale separations were performed on analytical and semipreparative size Chiralpak IA columns in combination with ethyl acetate‐based eluents.
Quinine carbamate chiral stationary phases: Systematic optimization of steric selector‐selectand binding increments and enantioselectivity by quantitative structure‐enantioselectivity relationship studies
Authors: Lämmerhofer Michael , Franco Pilar , Lindner Wolfgang 
Published: June 2006

AbstractA series of quinine carbamate‐based chiral stationary phases (CSPs) differing solely in the carbamate residue have been devised and a congeneric set of N‐3,5‐dinitrobenzoyl (DNB) amino acids (AAs) was separated into enantiomers on these CSPs by HPLC using a buffered hydro‐organic mobile phase. Some details on retention and chiral recognition mechanisms have been investigated by application of quantitative structure‐property relationship (QSPR) studies using the linear free energy relationship methodology, i. e., the extrathermodynamic approach. Retention factors of the high affinity enantiomer (log k2) and enantioselectivities (log α) were correlated with Taft's steric parameter as structural descriptor for the variability in the carbamate and AA residues, and statistically significant QSPR models could be obtained. They confirmed that the variance in the dependent variable (log k2, log α) is mainly associated with the steric bulkiness of the selectors' carbamate and of the AA residues. The retention factor of the second eluted enantiomers and the enantioselectivity first increased with steric bulkiness of the carbamate and AA residues, which may be explained by stronger dispersive interactions. After reaching an optimum, the dependent variable, however, declined with further increase of the steric bulkiness of the substituents, probably because of steric hindrance. The variability of the retention factors of the first eluted enantiomer could not be explained by steric descriptors. Instead, it has become obvious that the retention arises mainly from interactions of the DNB‐AA and the quinine carbamate backbone, as it turned out to be more or less constant and solely to a minute amount modulated by the carbamate residue and the AA side chain. The QSPR models were fully in agreement with an earlier postulated chromatographically and spectroscopically derived hypothetical selector‐selectand binding model.
Glutamate release inhibition ineffective in Levodopa‐induced motor complications
Authors: Bara‐Jimenez William , Dimitrova Tzvetelina D. , Sherzai Abdullah , Aksu Murat , Chase Thomas N. 
Published: June 2006

AbstractReported benefits of various glutamatergic receptor antagonists in Parkinson's disease (PD) prompted an evaluation of the antidyskinetic effect of a putative glutamate release inhibitor in 15 moderately advanced patients. In a 3‐week, double‐blind, proof‐of‐concept study, riluzole (200 mg/day) failed to alter parkinsonian or levodopa‐induced motor complication severity. Opposing effects of a generalized inhibition of glutamate‐mediated synaptic transmission may limit the usefulness of this approach to treat PD. © 2006 Movement Disorder Society
Helical chirality in hexamethylene triperoxide diamine
Authors: Guo Chunlei , Persons John , Harbison Gerard S. 
Published: June 2006

AbstractThe primary explosive hexamethylenetriperoxide diamine has previously been found to exist in the solid state as a racemic mixture of helically chiral, threefold symmetric enantiomers; another enantiomeric pair of low‐energy conformers has been predicted, but has never been observed. We show by solution 2D NMR at 14 T, in achiral solution and by addition of chiral shift reagents, that all four optically isomeric conformers coexist at slow equilibrium on the NMR timescale at room temperature, and can be observed. Calculations of the 1H and 13C NMR chemical shifts using gauge‐including atomic orbital methods are in excellent agreement with experiment; thermochemical calculation of the free energies in solution are in somewhat worse agreement, but correctly predict the relative stability of the conformers. Analysis of the effects of chiral shift reagents on the NMR spectra suggests that discrimination between chiral isomers is primarily around the molecular equator, around which the enantiomeric gauche OO linkages are arrayed. Copyright © 2006 John Wiley & Sons, Ltd.
1H and 13C chemical shifts for some 6,6a‐dihydrochromeno(3,4‐b)chromene derivatives
Authors: Mebale A‐J. Abogo , Maggiani A. , Brun P. 
Published: June 2006

AbstractThe 1H and 13C NMR resonances of five 6,6a‐dihydrochromeno(3,4‐b)chromene derivatives were assigned completely with certainty using a concerted application of one‐ and two‐dimensional experiments (DEPT, gs‐COSY, gs‐HMQC and gs‐HMBC). Copyright © 2006 John Wiley & Sons, Ltd.
Faster nerve regeneration after sciatic nerve injury in mice over‐expressing basic fibroblast growth factor
Authors: Jungnickel Julia , Haase Kristina , Konitzer Jens , Timmer Marco , Grothe Claudia 
Published: June 2006

AbstractBasic fibroblast growth factor (FGF‐2) is expressed in the peripheral nervous system and is up‐regulated after nerve lesion. It has been demonstrated that administration of FGF‐2 protects neurons from injury‐induced cell death and promotes axonal regrowth. Using transgenic mice over‐expressing FGF‐2 (TgFGF‐2), we addressed the importance of endogenously generated FGF‐2 on sensory neuron loss and sciatic nerve regeneration. After sciatic nerve transection, wild‐type and transgenic mice showed the same degree of cell death in L5 spinal ganglia. Also, the number of chromatolytic, eccentric, and pyknotic sensory neurons was not changed under elevated levels of FGF‐2. Morphometric evaluation of intact nerves from TgFGF‐2 mice revealed no difference in number and size of myelinated fibers compared to wild‐type mice. One week after crush injury, the number of regenerated axons was doubled and the myelin thickness was significantly smaller in transgenic mice. After 2 and 4 weeks, morphometric analysis and functional tests revealed no differences in recovery of sensory and motor nerve fibers. To study the role of FGF‐2 over‐expression on Schwann cell proliferation during the early regeneration process, we used BrdU‐labeling to mark dividing cells. In transgenic mice, the number of proliferating cells was significantly increased distal to the crush site compared to wild‐types. We propose that endogenously synthesized FGF‐2 influences early peripheral nerve regeneration by regulating Schwann cell proliferation, axonal regrowth, and remyelination. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006
Histological identification of bone fragments in archaeology: telling humans apart from horses and cattle
Authors: Cuijpers A. G. F. M. 
Published: June 2006

AbstractIn archaeology, it is not always possible to identify bone fragments. A novel approach was chosen to assess the potential of histology as an identification tool in those instances in which macroscopical study (e.g. by means of bone surface texture) has failed. This study concentrated on the diaphyses of long bones in three species of comparable size which are relevant to archaeology. Late juvenile and adult human diaphyseal bone structure was compared with the bone structure of horses and cattle. Since bone structure can differ even within a single bone, the restrictions in terms of bone category, bone part and species were deemed necessary for the development of a useful identification method for archaeological bone. The reference series comprised long bones from several individuals to broaden the insight into variations in diaphyseal bone structure within a single species.A general difference in the primary bone types was found between humans and the two large mammals. Human bone displayed lamellar bone types, whereas horses and cattle showed fibrous bone types. The only exceptions were separated growth layers. A difference in the secondary bone structure was also observed. A large number of connecting, primary (Volkmann's) canals, giving the secondary bone a reticular aspect, were common in horses and cattle. They were not, however, present in the human bones studied.To confirm the validity and applicability of these differences, a blind test was conducted on 15 diaphyseal fragments of identified long bones from archaeological sites. The results were very promising. Although four fragments could not be identified due to severe degradation, all the others were correctly attributed. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and aggregation of amine‐cored polyamidoamine dendrons synthesised without invoking a protection/deprotection strategy
Authors: King Amy SH , Martin Ian K , Twyman Lance J 
Published: June 2006

AbstractThe synthesis of a series of amine‐cored N,N‐dimethyl‐terminated polyamidoamine dendrons with the potential to be modified at their focal point is reported. The use of an aniline core enables the target molecules to be synthesised without resorting to the use of a time‐consuming and expensive protection/deprotection strategy. After synthesising these molecules significant frothing in aqueous solution at millimolar concentrations was noticed, a property associated with aggregation. The critical micelle concentrations were therefore measured and found to occur at relatively low dilutions (in the range 10−4–10−5 mol L−1). Copyright © 2006 Society of Chemical Industry
Optical Pyrometry of Fireballs of Metalized Explosives
Authors: Goroshin Samuel , Frost David L. , Levine Jeffrey , Yoshinaka Akio , Zhang Fan 
Published: June 2006

AbstractFast‐response optical diagnostics (a time‐integrated spectrometer and two separate fast‐response three‐color pyrometers) are used to record the transient visible radiation emitted by a fireball produced when a condensed explosive is detonated. Measurement of the radiant intensity, in several narrow wavelength bands, is used to estimate the temperature of the condensed products within the fireball. For kg‐scale conventional oxygen‐deficient homogeneous TNT and nitromethane explosive charges, the radiant intensity reaches a maximum typically after tens of milliseconds, but the measured fireball temperature remains largely constant for more than 100 ms, at a value of about 2,000 K, consistent with predictions using equilibrium thermodynamics codes. When combustible metal particles (aluminum, magnesium or zirconium) are added to the explosive, reaction of the particles enhances the radiant energy and the fireball temperature is increased. In this case the fireball temperatures are lower than equilibrium predictions, but are consistent with measurements of particle temperature in single particle ignition experiments.