bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solvent Effects on Complexation of Molybdenum(VI) with Nitrilotriacetic Acid in Different Aqueous Solutions of Propanol
Authors: Mohammadi Behrouz , Mohammadi Jalal 
Published: March 2007

AbstractBy using spectrophotometric and potentiometric techniques the formation constants of the species formed in the systems H++Mo(VI)+nitrilotriacetic acid and H++nitrilotriacetic acid have been determined in aqueous solutions of propanol at 25 °C and constant ionic strength 0.1 mol·dm−3 sodium perchlorate. The composition of the complex was determined by the continuous variation method. It was shown that molybdenum(VI) forms a mononuclear 1:1 complex with nitrilotriacetic acid of the type MoO3L−3 at −lg[H+]=5.8. The formation constants in various media were analyzed in terms of Kamlet and Taft's parameters. Linear relationships were observed when lg KS was plotted versus p*. Finally, the results were discussed in terms of the effect of solvent on complexation.
Synthesis, Characterization and Biological Activity of Diorganotin(IV) Complexes of N‐(3,5‐Dibromo‐salicylidene)‐ α‐amino Acid
Authors: Tian Lai‐Jin , Sun Yu‐Xi , Zheng Xiao‐Liang , Liu Xi‐Jie , Yu You , Liu Xue‐Li , Qian Bo‐Chu 
Published: March 2007

AbstractThe diorganotin(IV) complexes of N‐(3,5‐dibromosalicylidene)‐α‐amino acid, R′2Sn(2‐O‐3,5‐Br2C6H2CHNCHRCOO)(where R=H, Me, i‐Pr, Bz; R′ =n‐Bu, Cy), were synthesized by the reactions of diorganotin dichlorides with in situ formed potassium salt of N‐(3,5‐dibromosalicylidene)‐α‐amino acid and characterized by elemental analysis, IR and NMR (1H, 13C and 119Sn) spectra. The crystal structures of n‐Bu2Sn(2‐O‐3,5‐Br2C6H2CHNCHRCOO)(R=i‐Pr, Bz) and Cy2Sn(2‐O‐3,5‐Br2C6H2CHNCHRCOO)(R=Me, Bz) were determined by X‐ray single crystal diffraction and showed that the tin atoms are in a distorted trigonal bipyramidal geometry to form five‐ and six‐membered chelate rings with the tridentate ligand. Bioassay results indicated that the compounds possess better in vitro antitumour activity against three human tumour cell lines, HeLa, CoLo205 and MCF‐7, than cis‐platin and moderate anti‐bacterial activity against two bacteria, E. coli and S. aureus.
Synthesis of Mixed Tail Triphenylene Discotic Liquid Crystals: Molecular Symmetry and Oxygen‐Atom Effect on the Stabilization of Columnar Mesophases
Authors: Zhao Ke‐Qing , Hu Ping , Wang Bi‐Qin , Yu Wen‐Hao , Chen Hong‐Mei , Wang Xin‐Ling , Shimizu Yo 
Published: March 2007

AbstractSmall change in chemical structure of discotic liquid crystals can cause big difference in their mesomorphism. Replacing of the alkoxy peripheral chains of triphenylene by oxygen‐atom containing ester chains would result in novel mesomorphism. A series of mixed tail triphenylenes containing propoxyacetyloxy and alkoxy, abbreviated as C18H6(OCnH2n+1)3(OCOCH2OC3H7)3, n=4–8, and hexa(propyloxyacetyloxy)triphenylene, C18H6(OCOCH2‐OC3H7)6 were synthesized. Thermal gravimetry analysis (TGA) of three discogens showed that they had good thermal stability till 350 °C. The mesomorphism was investigated through differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The preliminary X‐ray diffraction (XRD) results of one compound showed that it exhibited ordered hexagonal columnar (Colho) mesophase. These mixed tail triphenylene derivatives possessed much stable Colho mesophase and wider mesophase ranges than their hexaalkoxytriphenylene C18H6(OR)6 and hexaalkanoyloxytriphenylene C18H6(OCOR′)6 analogues. The asymmetrical compounds 2,6,11‐trialkoxy‐3,7,10‐tri(2‐propyloxyacetyloxy)triphenylenes with n=5–8 displayed higher clearing points and wider temperature ranges than their symmetrical isomers 2,6,10‐trialkoxy‐3,7,11‐tri(2‐propyloxyacetyloxy)‐
triphenylenes, while C18H6(OCOCH2OC3H7)6 had the highest clearing point due to the β‐oxygen‐atom effect.
Cyclopenta[d]pyrimidines and Dihydropyrrolo[2,3‐d]pyrimidines as Potent and Selective Corticotropin‐Releasing Factor 1 Receptor Antagonists
Authors: Arban Roberto , Benedetti Roberto , Bonanomi Giorgio , Capelli Anna‐Maria , Castiglioni Emiliano , Contini Stefania , Degiorgis Fabio , Di Felice Pina , Donati Daniele , Fazzolari Elettra , Gentile Gabriella , Marchionni Chiara , Marchioro Carla , Messina Flavia , Micheli Fabrizio , Oliosi Beatrice , Pavone Francesca , Pasquarello Alessandra , Perini Benedetta , Rinaldi Marilisa , Sabbatini Fabio M. , Vitulli Giovanni , Zarantonello Paola , Di Fabio Romano , St‐Denis Yves 
Published: March 2007

AbstractTwo new classes of potent and selective CRF1 receptor antagonists are presented. Exploration of general templates 3 and 4 through modifications of the top amine and bottom phenyl substituents led to optimization of the in vitro affinity and pharmacokinetic profiles. The typical alkyl chains present in the top region of CRF1 antagonists were replaced by substituted heteroaryl moieties, leading to a dramatic improvement of the metabolic stability. This improvement was apparent when the compounds were dosed in vivo: several compounds exhibited low plasma clearance, good oral bioavailability, and high brain penetration. As a consequence of their outstanding pharmacokinetic profiles, these CRF1 antagonists, as exemplified by compound 4 fi (4‐(4‐bromo‐3‐methyl‐1H‐pyrazol‐1‐yl)‐7‐(2,4‐dichlorophenyl)‐2‐methyl‐6,7‐dihydro‐5H‐pyrrolo[2,3‐d]pyrimidine), produced a dose‐dependent “anxiolytic‐like” effect when administered orally, decreasing the vocalization of rat pups.
Understanding Multiple‐Pulse Experiments ‐ An Introduction to the Product‐Operator Description I. Starting with the Vector Model
Authors: Ziessow Dieter 
Published: March 2007

AbstractThis is the first of three articles which deal with the concepts and rules of the product operator description (POD) and their applications in multidimensional NMR. Since the majority of POD rules are consistent with those of the vector model, the latter is presented here, but only to the required extent. This includes topics such as sense of rotation, chemical shift evolution, t2 and t1 quadrature detection with phase‐shifted pulses, handling of complex FID signals, and refocussing. The second spectral dimension is introduced on the basis of delayed acquisition and the pulsepair technique for a single spin and requires no theoretical background other than the vector model. Coupled‐spin systems are also treated, and it is shown by three distinct examples how the vector model works for 180° pulses.
The Bloch equations. How to have fun calculating what happens in NMR experiments with a personal computer
Authors: Roberts John D. 
Published: March 2007

AbstractThe so‐called “phenomenological” differential equations derived for nuclear magnetic induction by Felix Bloch in 1946 can easily be integrated by numerical methods and can give interesting, as well as very useful, results with the processing power of ordinary personal computers. This article deals with (1) the derivation of the Bloch equations, (2) slow‐passage continuous‐wave (CW) spectral calculations, (3) a procedure for numerical integration and several illustrations of how numerical integration can be used for generation of CW spectra, (4) free induction decays, and (5) the results of multipulse sequences, such as those used in determination of T1 and T2. A listing of the source code of a simple BASIC program for numerical integration of the Bloch equations with personal computers is included in an appendix.
Imatinib combined with mitoxantrone/etoposide and cytarabine is an effective induction therapy for patients with chronic myeloid leukemia in myeloid blast crisis
Authors: Fruehauf Stefan , Topaly Julian , Buss Eike C. , Fischer Thomas , Ottmann Oliver G. , Emmerich Bertold , Müller Martin C. , Schuld Peter , Balleisen Leopold , Hehlmann Rüdiger , Ho Anthony D. , Hochhaus Andreas 
Published: March 2007

AbstractBACKGROUNDDespite advances in drug therapy and allogeneic stem cell transplantation (allo‐SCT), the prognosis of patients with chronic myeloid leukemia (CML) in blast crisis remains poor. Imatinib has demonstrated synergistic effects in vitro with mitoxantrone, etoposide, and cytarabine.METHODSA Phase I/II trial was performed in patients with CML myeloid blast crisis. Patients were treated with imatinib + mitoxantrone/etoposide in four cohorts: mitoxantrone 10 mg/m2/day and etoposide 100 mg/m2/day for 2 or 3 consecutive days and imatinib 600 mg/day from Day 15 (cohorts 1 and 2) or from Day 1 (cohorts 3 and 4). After hematologic reconstitution after the cytopenic phase, cytarabine was given at a dose of 10 mg/m2/day in addition to imatinib as maintenance treatment.RESULTSA total of 16 patients were available for analysis, median age 59 years (range, 37–74). All patients who received more intensive induction treatment (cohorts 3 and 4, n = 7) achieved a hematologic response (HR). In contrast, HR was achieved in only 6 of 9 patients treated in cohorts 1 and 2. The induction treatment was well tolerated. Six patients who achieved HR received an allo‐SCT with myeloablative conditioning. The median survival in the transplant group was 16.2 months vs 4.7 months in the group with conventional treatment only (P = .067).CONCLUSIONSThe combination of mitoxantrone/etoposide and imatinib is well tolerated, with mild nonhematologic toxicity even in older patients. Eligible patients benefit from allo‐SCT after response to the induction treatment. Cancer 2007. © 2007 American Cancer Society.
Numerical study of lid‐driven flow in orthogonal and skewed porous cavity
Authors: Jaya Krishna D. , Basak Tanmay , Das Sarit K. 
Published: March 2007

AbstractEffects of Reynolds number, Darcy number, porosity, aspect ratio and skewness are studied in detail for lid‐driven cavity flows filled with fluid‐saturated porous medium. A generalized non‐Darcy approach has been considered to account for linear and non‐linear drag forces. The governing equations are solved by using finite volume method. A quadrilateral cell in a semi‐staggered arrangement has been employed and is transformed into a standard square element using local body‐fitting co‐ordinates by co‐ordinate transformation. Details of the flow physics reveal that by the reduction of Darcy number, the primary vortex becomes weaker and tends to move towards the lid. As a measure of volume flow rate maximum stream function value is considered. It is found that, with the reduction in Darcy number and with the increase in Reynolds number and skewness the maximum stream function value reduces. Copyright © 2007 John Wiley & Sons, Ltd.
The Cyclohexasilanes Si6H11X and Si6Me11X with X=F, Cl, Br and I: A Quantum Chemical and Raman Spectroscopic Investigation of a Multiple Conformer Problem
Authors: Hölbling Margit , Flock Michaela , Hassler Karl 
Published: March 2007

AbstractThe conformers of the monohalocyclohexasilanes, Si6H11X (X=F, Cl, Br or I) and the haloundecamethylcyclohexasilanes, Si6Me11X (X=F, Cl, Br or I) are investigated by DFT calculations employing the B3LYP density functional and 6‐31+G* basis sets for elements up to the third row, and SDD basis sets for heavier elements. Five minima are found for Si6H11X—the axial and equatorial chair conformers, with the substituent X either in an axial or equatorial position—and another three twisted structures. The equatorial chair conformer is the global minimum for the X=Cl, Br and I, the axial chair for X=F. The barrier for the ring inversion is ∼13  kJ mol−1 for all four compounds. Five minima closely related to those of Si6H11X are found for Si6Me11X. Again, the equatorial chair is the global minimum for X=Cl, Br and I, and the axial chair for X=F. Additionally, two symmetrical boat conformers are found as local minima on the potential energy surfaces for X=F, Cl and Br, but not for X=I. The barrier for the ring inversion is ∼14–16 kJ mol−1 for all compounds. The conformational equilibria for Si6Me11X in toluene solution are investigated using temperature dependent Raman spectroscopy. The wavenumber range of the stretching vibrations of the heavy atoms X and Si from 270–370 cm−1 is analyzed. Using the van′t Hoff relationship, the enthalpy differences between axial and equatorial chair conformers (Hax−Heq.) are 1.1 kJ mol−1 for X=F, and 1.8 to 2.8 kJ mol−1 for X=Cl, Br and I. Due to rapid interconversion, only a single Raman band originating from the “averaged” twist and boat conformers could be observed. Generally, reasonable agreement between the calculated relative energies and the experimentally determined values is found.
A review of seismic acoustic imaging by reverse‐time migration
Authors: McMechan George A. 
Published: March 2007

AbstractSeismic migration is the process by which an acoustic seismic wavefield, containing scattered/diffracted waves recorded as a function of time, is converted into a focussed image of the corresponding spatial distribution of scatters/diffractors. One method of implementing this is by reverse‐time extrapolation of the recorded wavefield using the data as boundary values in a finite‐difference solution of the scalar wave equation, plus application of an excitation‐time imaging condition. Conceptually, and numerically, this approach is precisely the inverse of the corresponding forward problem of simulation of the response of a given model to an acoustic source.
Seismic inversion: Travel times or amplitudes?
Authors: Treitel Sven 
Published: March 2007

AbstractSeismic inversion is now the focus of much effort in our industry. Its performance depends critically on the response of the abstract model chosen to mimic the real earth and on the optimization criterion employed to match this response to the actual seismogram. There are two broad categories: travel‐time invorsion and amplitude inversion. When we invert for travel‐times, we seek a subsurface model whose event arrival times best match picked arrivals on the real data. When we invert for amplitudes, we search for a subsurface model whose seismic signature best matches the entire recorded data, and not merely the arrival times. Of the two methods, travel‐time inversion is by far the simplest and is currently in widespread use. Amplitude inversion is more general because it makes full use of the recorded data, but implementation is still very costly and the approach has not yet seen extensive practical use. Neither technique can give us the unique subsurface model—that is, there will always be a multiplicity of subsurface configurations whose responses match the data within a desired tolerance. Physical insight is required to rule out those models devoid of geological significance.
An iterative solution of the two‐dimensional electromagnetic inverse scattering problem
Authors: Wang Y. M. , Chew W. C. 
Published: March 2007

AbstractA new method, based on an iterative procedure, for solving the two‐dimensional inverse scattering problem is presented. This method employs an equivalent Neumann series solution in each iteration step. The purpose of the algorithm is to provide a general method to solve the two‐dimensional imaging problem when the Born and the Rytov approximations break down. Numerical simulations were calculated for several cases where the conditions for the first order Born approximation were not satisfied. The results show that in both high and low frequency cases, good reconstructed profiles and smoothed versions of the original profiles can be obtained for smoothly varying permittivity profiles (lossless) and discontinuous profiles (lossless), respectively. A limited number of measurements around the object at a single frequency with four to eight plane incident waves from different directions are used. The method proposed in this article could easily be applied to the three‐dimensional inverse scattering problem, if computational resources are available.
High‐Resolution deconvolution techniques and their applications in ultrasonic NDE
Authors: Chen C. H. , Sin S. K. 
Published: March 2007

AbstractThe technique of ultrasonic pulse echo measurement is a very cost‐effective method of non‐destructive evaluation (NDE). These measurements are, however, usually masked by the characteristics of the measuring equipment and the propagation paths taken by the ultrasonic pulse. With a proper modeling of the pulse echo, these effects can be reduced by deconvolution. In this paper, several deconvolution algorithms that have been popularly used in other areas such as seismic explorations are revised and adapted to ultrasonic NDE applications. Simulation results are presented to support the feasibility of using these algorithms to extract impulse responses from the ultrasonic pulse echoes for use in defect classifications. The performances and computational complexities of these algorithms are analyzed and compared. In addition, application of these deconvolution techniques to B‐scan enhancement is also discussed.
An introduction to chaotic and random time series analysis
Authors: Scargle Jeffrey D. 
Published: March 2007

AbstractChaos refers to the paradoxical evolution of a deterministic system in a way that is disordered—to the point that the time dependence of the physical variables appears stochastic. A need for data analysis procedures to detect, model, and separate chaotic and random processes has arisen from this recently understood paradigm. Many special techniques have been designed for chaotic data; the unification of these with conventional time series analysis is a developing field.This tutorial uses examples to explain the origin of chaotic behavior and the relation of chaos to randomness. Two powerful mathematical results are described: (1) a representation theorem guarantees the existence of a specific time‐domain model for chaos and addresses the relation between chaotic, random, and strictly deterministic processes, and (2) a theorem assures that information on the behavior of a physical system in its complete state space can be extracted from time‐series data on a single observable.These theorems form the basis of a practical data analysis scheme, as follows: given N observations of a variable Y, i.e., {Yn, n = 1,2,3, …, N}, define X = A * Y and maximize, with respect to the parameters of A, a function H(X) that measures degree of chaos. This maximization is carried out by minimizing the dimension covered by the data in the M‐dimensional space (Xn, Xn+1, Xn+2, …, Xn+M−1). The resulting dimension D either (1) increases continuously with M or (2) levels off and remains constant (= Dmax) beyond a certain point. In case (1) or if Dmax is quite large X is random; if case (2) holds and Dmax is small, we have chaos. The inverse of A found in this procedure is an estimate of the filter in the moving average model for Y.
Wavelet estimation: A first step toward increasing image resolution
Authors: Brown Raymon L. 
Published: March 2007

AbstractIn many fields of imaging, the shape of the function describing the incident source wave (“the wavelet”) is known. In seismic exploration, this luxury is not available since seismic sources are affected by their environment. The resultant wavelet that is transmitted into the earth is quite different from any measurement that may be conducted near the source. To many seismic explorationists the wavelet has almost taken a mythical position of stature. More Black Art, mysterious assumptions, advanced mathematics, and handwaving go into wavelet estimation than any other aspect of seismic exploration. The reason for all the effort stems from the need to explore targets that are fractions of wavelengths. This presentation describes some of the methods used in seismic exploration to preserve bandwidth, estimate the wavelet shape, and invert the data to obtain a sharp image.
NOSER: An algorithm for solving the inverse conductivity problem
Authors: Cheney M. , Isaacson D. , Newell J. C. , Simske S. , Goble J. 
Published: March 2007

AbstractThe inverse conductivity problem is the mathematical problem that must be solved in order for electrical impedance tomography systems to be able to make images. Here we show how this inverse conductivity problem is related to a number of other inverse problem. We then explain the workings of an algorithm that we have used to make images from electrical impedance data measured on the boundary of a circle in two dimensions. This algorithm is based on the method of least squares. It takes one step of a Newton's method, using a constant conductivity as an initial guess. Most of the calculations can therefore be done analytically. The resulting code is named NOSER, for Newton's One‐Step Error Reconstructor. It provides a reconstruction with 496 degrees of freedom. The code does not reproduce the conductivity accurately (unless it differs very little from a constant), but it yields useful images. This is illustrated by images reconstructed from numerical and experimental data, including data from a human chest.
Limited‐Angle inverse scattering problems and their applications for geophysical explorations
Authors: Wang Y. M. , Chew W. C. 
Published: March 2007

AbstractThe effect of the limited‐angle measurements on the nonlinear inverse scattering problem is investigated. Because of incomplete information obtained in the limited‐angle inverse problem, the linearized system matrix in the inversion procedure becomes more ill‐conditioned compared to that of the conventional inverse scattering problem where the receivers are placed in a circle that completely surrounds the object. Consequently, the quality of the reconstruction is considerably reduced, and sometimes it is almost impossible to reconstruct the profile because of the sparsity of the measurement data. To overcome the above difficulty, a boosting procedure, which will help us to obtain the maximum amount of information for an arbitrary predefined experimental setup, has been proposed based on a physical viewpoint. The results of the computer simulations for well‐to‐well tomography demonstrate that by applying the boosting procedure the quality of the reconstruction and the speed of the convergence are improved significantly. Furthermore, for subsurface detection where both the transmitters and receivers are confined to the ground, the reconstruction becomes possible after applying the boosting procedure.
Imaging techniques for cable network structures
Authors: Eisenloffel K. , Adeli H. 
Published: March 2007

AbstractImaging techniques are presented for developing interactive computer display of cable network structures on a microcomputer such as the IBM PS/2®. These structures create surfaces formed by an orthogonal mesh of cables and are primarily loaded normal to the surface. A three‐dimensional perspective representation of network structures is developed for fast drawing of cable structures on microcomputers.
Residual‐Based robust estimation and image‐motion analysis
Authors: Zhuang Xinhua , Zhao Yunxin , Huang Thomas S. 
Published: March 2007

AbstractWe explain that the task of multiple rigid motion segmentation and estimation from image feature point correspondence demands an estimator of high robustness. We show that a heuristics‐based partial modeling approach can be used to develop a highly robust estimator called the MF estimator for general regression, where “MF” represents an abbreviation of Model Fitting. Finally, we provide experimental results in estimating single rigid motion from a mixture of 2D‐2D (or image‐image), 3D‐2D (or range‐image) and 3D‐3D (or range‐range) corresponding point data by using the proposed MF estimator. As will be seen, only four well matched corresponding point pairs are needed to get a good estimate of motion parameters no matter how many mismatched corresponding point pairs (or outliers) occur. The article represents an initial effort towards robust image‐motion analysis.