bluuebunny/crossref_metadata_2025_split huggingface dataset:
3‐Fluoropiperidines and N‐Methyl‐3‐fluoropiperidinium Salts: The Persistence of Axial Fluorine
Authors: Sun Aiming , Lankin David C. , Hardcastle Kenneth , Snyder James P. 
Published: January 2005

AbstractIt has previously been shown that the fluorine atom in N‐protonated 3‐fluoropiperidine salts in water strongly prefers the axial orientation in the six‐membered ring chairs. In the present work we examine the proposition that the N‐methyl salts are equally disposed to present axial fluorine. Initially, we explored this point by comparing the structures of the corresponding NH2+, NHMe+, and NMe2+ salts by means of density functional theory (DFT), ab initio, and MMFF force field calculations with and without aqueous solvation models. The predictions unambiguously pointed to axial fluorine for all salts investigated, including those with simultaneous axial F and (N)Me. The calculations were followed by synthesis of the corresponding series of 4,4‐diphenylpiperidinium salts. These were evaluated by one‐ and two‐dimensional NMR spectroscopy in [D6]DMSO to fully corroborate the axial disposition of the fluorine in each of the compounds. X‐ray crystal structure determinations were likewise performed for the diphenyl‐3‐fluoro NH2+ and NMe2+ systems to substantiate axial‐F. Comparison of the X‐ray structures of the fluorinated and unfluorinated NMe2+ salts reveals that the fluorine resides axial in spite of substantial steric compression. While the charge‐dipole phenomenon responsible for the axial‐F conformation in the parent protonated fluoropiperidinium compounds carries over to doubly alkylated salts, we show that it extends to molecular orientation in the packing of the unit cells in the solid state as well. Finally, using the computational methods that successfully motivated our synthesis and structural work, we have made predictions for a number of new structures and re‐examined some parallel results reported by the Eliel group in the early 1970s. Although CF⋅⋅⋅HN hydrogen bonds are reported to be weak and few in number, the CF⋅⋅⋅HN charge‐dipole orienting effect is a powerful directing force that matches the hydrogen‐bond in both its energetic contribution and conformational consequences.
Identification of Muir–Torre syndrome among patients with sebaceous tumors and keratoacanthomas
Authors: Ponti Giovanni , Losi Lorena , Di Gregorio Carmela , Roncucci Luca , Pedroni Monica , Scarselli Alessandra , Benatti Piero , Seidenari Stefania , Pellacani Giovanni , Lembo Luigi , Rossi Giuseppina , Marino Massimiliano , Lucci‐Cordisco Emanuela , de Leon Maurizio Ponz 
Published: January 2005

AbstractBACKGROUNDThe Muir–Torre syndrome (MTS) is an autosomal‐dominant genodermatosis characterized by the presence of sebaceous gland tumors, with or without keratoacanthomas, associated with visceral malignancies. A subset of patients with MTS is considered a variant of the hereditary nonpolyposis colorectal carcinoma, which is caused by mutations in mismatch‐repair genes. The objective of the current study was to evaluate whether a combined clinical, immunohistochemical, and biomolecular approach could be useful for the identification of Muir–Torre syndrome among patients with a diagnosis of sebaceous tumors and keratoacanthomas.METHODSThe authors collected sebaceous skin lesions and keratoacanthomas recorded in the files of the Pathology Department of the University of Modena during the period 1986–2000. Through interviews and examination of clinical charts, family trees were drawn for 120 patients who were affected by these skin lesions.RESULTSSeven patients also were affected by gastrointestinal tumors, thus meeting the clinical criteria for the diagnosis of MTS. In the MTS families, a wide phenotypic variability was evident, both in the spectrum of visceral tumors and in the type of skin lesions. Microsatellite instability was found in five MTS patients: These patients showed concordance with immunohistochemical analysis; moreover, a constitutional mutation in the MSH2 gene was found in 1 patient. Lack of expression of MSH2/MSH6 or MLH1 proteins was evident in the skin lesions and in the associated internal malignancies of 3 patients and 2 patients with MTS, respectively.CONCLUSIONSThe clinical, biomolecular, and immunohistochemical characterization of sebaceous skin lesions and keratoacanthomas may be used as screening for the identification of families at risk of MTS, a disease that is difficult to recognize and diagnose. Cancer 2005. © 2005 American Cancer Society.
A Theoretical Analysis of the Coordination Modes of CuIIwith Penicillins: Activation of the β‐Lactam CN Bond
Authors: Campomanes Pablo , Menéndez M. Isabel , López Ramón , Sordo Tomás L. 
Published: January 2005

AbstractThe interaction of CuIIwith 6‐formylamino‐3α‐carboxypenam and 6‐acetylamino‐3α‐carboxypenam was investigated by means of DFT calculations with the UB3LYP functional. Nine different modes of complexation between CuIIand 6‐formylamino‐3α‐carboxypenam were located. When two water molecules directly bonded to CuIIare included in the calculations on 6‐acetylamino‐3α‐carboxypenam as penicillin model, only six CuII(H2O)2–6‐acetylamino‐3α‐carboxypenam complexes (1 S–6 S) are found. In solution the four most stable complexes obtained from our calculations,6 S,1 S,2 S, and3 S, exhibit CuIIin square‐planar coordination with at least one bond to the carboxylate group, in agreement with experimental evidence. Complexes6 S,1 S, and3 Swere previously suggested by available experimental evidence. In three of the most stable complexes (6 S,2 S, and3 S) the β‐lactam CN bond is remarkably activated and displays CN bond lengths similar to those found in some tetrahedral intermediates located for the hydrolysis of 2‐azetidinones. This suggests that these kinds of complexes belong to the reaction coordinate for the degradation ofβ‐lactam antibiotics in the presence of CuII.
Determining the Geometry of Hydrogen Bonds in Solids with Picometer Accuracy by Quantum‐Chemical Calculations and NMR Spectroscopy
Authors: Schulz‐Dobrick Martin , Metzroth Thorsten , Spiess Hans Wolfgang , Gauss Jürgen , Schnell Ingo 
Published: January 2005

AbstractThe structure of multiply hydrogen‐bonded systems is determined with picometer accuracy by a combined solid‐state NMR and quantum‐chemical approach. On the experimental side, advanced 1H15N dipolar recoupling NMR techniques are capable of providing proton–nitrogen distances of up to about 250 pm with an accuracy level of ±1 pm for short distances (i.e., around 100 pm) and ±5 pm for longer ones (i.e., 180 to 250 pm). The experiments were performed under fast magic‐angle spinning, which ensures sufficient dipolar decoupling and spectral resolution of the 1H resonance lines. On the quantum‐chemical side, the structures of the hydrogen‐bonded systems were computationally optimised, yielding complete sets of nitrogen–proton and proton–proton distances, which are essential for correctly interpreting the experimental NMR data. In this way, nitrogen–proton distances were determined with picometer accuracy, so that vibrational averaging effects on dipole–dipole couplings need to be considered. The obtained structures were finally confirmed by the complete agreement of computed and experimental 1H and 15N chemical shifts. This demonstrates that solid‐state NMR and quantum‐chemical methods ideally complement each other and, in a combined manner, represent a powerful approach for reliable, high‐precision structure determination whenever scattering techniques are inapplicable.
A method for the approximate synthesis of cellular non‐linear networks—Part 1: Circuit definition
Authors: Storace Marco , Repetto Lorenzo , Parodi Mauro 
Published: January 2005

AbstractIn this paper, we face the problem of the synthesis of cellular non‐linear networks (CNNs) able to find approximate solutions of either partial differential equations or functional minimization problems. In particular, the paper deals with the approximate synthesis of the multi‐terminal resistors that include all the non‐linearities of such dynamic circuits. The proposed approximation method is based on the piecewise‐linear (PWL) approach developed by Juliánet al. in the last few years, but it resorts to a different definition of the inner product and hence to other PWL basis functions. The method is applied to a case‐study concerning a CNN devoted to image processing. Copyright © 2003 John Wiley & Sons, Ltd.
90dB‐DR 3.3V CMOS single‐ended‐to‐fully differential and fully differential‐to‐single‐ended amplifiers for audio applications
Authors: Boarin G. , Colonna V. , Gandolfi G. , Stefani F. , Baschirotto A. 
Published: January 2005

AbstractThis paper presents the design and the realization of single‐ended‐to‐fully differential and fully differential‐to‐single‐ended amplifiers to be used in an audio signal processing system. The proposed blocks allow to reduce significantly the pin number of the developed system, while guaranteeing the high quality (16bit) performance required in an audio channel. The proposed circuits have been realized in a standard 3.3V 0.35 µm CMOS technology and achieve a Dynamic Range in excess of 90dB with a Total Harmonic Distortion lower than ‐80dB for a full scale signal amplitude. Their power consumption (≈6mW and each) and the area (0.1mm2each) are finally negligible with respect to the other blocks in the overall systems. Copyright © 2003 John Wiley & Sons, Ltd.
Experimental Study and Modelling of Formation and Decay of Active Species in an Oxygen Discharge
Authors: Diamy A.‐M. , Legrand J.‐C. , Rybkin V. V. , Smirnov S. A. 
Published: January 2005

AbstractA microwave (2.45 GHz) oxygen discharge (3 hPa, 150 W, 50 mL.min–1) is studied by optical emission spectroscopy of O(5P) (line 777.4 nm) and of the atmospheric system of O2(head‐line 759.4 nm). Calibration of the spectral response of the optical setup is used to determine the concentrations of O(5P) and O2(b). The concentration of the O(5P) atoms is in the range 108–109 cm–3 and the concentration of the O2(b) molecules is in the range 1014 – 2 × 1014 cm–3 along the discharge tube. An attempt is made to simulate the experimental results by using coupling the Boltzmann equation, homogeneous energy transfer V‐V and V‐T, heterogeneous reactions on the walls (energy transfer and recombination of atoms) and a kinetic scheme (electronic transfer and chemical reactions). The Boltzmann equation includes momentum transfer, inelastic and superelastic processes and e‐e collisions. V‐V and V‐T transfer equations are obtained from the SSH theory and the kinetic scheme includes 65 reactions with 17 species [electrons e, ions O– and O2–, fundamental electronic neutral species O(3P), O2, O2(X,v), O3 and excited neutral species O2(a), O2(b), O2(A), O(1D), O(1S), O(5P), O(4d 5Do), O(5s 5So), O(3d 5Do) and O(4s 5So)]. A fair agreement between experimental results and modelling is obtained with the following set of fitting values:– heterogeneous deactivation coefficient for O2(b) γ = 2.6 × 10–2;– rate constant of reaction [O(1D) + O(3P) → 2 O(3P)] k34 = 1.4 × 10–11 cm3.s–1;– electron concentration in the range 1010 – 1011 cm–3.Modelling shows that the recombination coefficient for oxygen atoms on the silica wall (range 1.4 × 10–3 – 0.2 × 10–3) is of the same order as the values obtained in a previous paper and that the ratio ([O] / 2 [O2]initial) is about 33–50%. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
One‐sided flame spread phenomena of a thermally thin composite cotton/fiberglass fabric
Authors: Kleinhenz Julie , Ferkul Paul , Pettegrew Richard , Sacksteder Kurt R. , T'ien James S. 
Published: January 2005

AbstractAs an experimental necessity, past flame spread studies have relied on fast burning cellulosic papers. For the longer duration tests planned for the International Space Station a 50% fiberglass, 50% cotton composite fabric is better suited for the novel fuel feeding system in the compact hardware design of a current microgravity combustion experiment. The fabric's combustion characteristics in normal gravity include unexpected cases where a flame can be sustained on one side of the fuel. One‐sided flames are smaller in size than their two‐sided counterparts, and propagate at half the speed. Surface temperature distributions were measured using infrared imaging and indicated a high temperature region caused by the non‐flammable fiberglass. Breaching the fiberglass matrix made it possible for the flame to transfer to the other side of the fuel, suggesting that the fiberglass matrix acts as a flame arrester. Copyright © 2004 John Wiley & Sons, Ltd.
A high‐resolution scheme for the equations governing 2D bed‐load sediment transport
Authors: Hudson Justin , Sweby Peter K. 
Published: January 2005

AbstractThis paper investigates how to accurately numerically approximate the equations governing 2D sediment transport by considering two approaches: a steady and unsteady approach. A high‐resolution scheme based on Roe's scheme is used to approximate both approaches with the results compared for a 2D test case. Copyright © 2005 John Wiley & Sons, Ltd.
An implicit multiblock coupling for the incompressible Navier–Stokes equations
Authors: Romé Christophe , Glockner Stéphane 
Published: January 2005

AbstractIn the present work, we describe an interface treatment of multiblock computation for the incompressible Navier–Stokes equations discretized upon a finite volume marker and cell (MAC) approach. The connection between the different blocks is based on velocity interpolation only. The originality of this work is that the polynomial interpolation coefficients are present in the final linear system and ensure that the equations are globally resolved. Copyright © 2005 John Wiley & Sons, Ltd.
A new symmetry‐preserving Cartesian‐grid method for computing flow past arbitrarily shaped objects
Authors: Dröge Marc , Verstappen Roel 
Published: January 2005

AbstractThis paper deals with a numerical method for solving the unsteady, incompressible Navier–Stokes equations in domains of arbitrarily shaped boundaries, where the boundary is represented using the Cartesian‐grid approach. We introduce a novel cut‐cell discretization, which preserves the symmetry of convection and diffusion. That is, convection is discretized by a skew‐symmetric operator and diffusion is approximated by a symmetric, positive‐definite coefficient matrix. The resulting semi‐discrete (continuous in time) system conserves the kinetic energy if the dissipation is turned off; the energy decreases if dissipation is turned on. The method is successfully tested for an incompressible, unsteady flow around a circular cylinder atRe=100. Copyright © 2005 John Wiley & Sons, Ltd.
Haplotype sharing transmission/disequilibrium tests that allow for genotyping errors
Authors: Sha Qiuying , Dong Jianping , Jiang Renfang , Chen Huann‐Sheng , Zhang Shuanglin 
Published: January 2005

AbstractThe present study introduces new Haplotype Sharing Transmission/Disequilibrium Tests (HS‐TDTs) that allow for random genotyping errors. We evaluate the type I error rate and power of the new proposed tests under a variety of scenarios and perform a power comparison among the proposed tests, the HS‐TDT and the single‐marker TDT. The results indicate that the HS‐TDT shows a significant increase in type I error when applied to data in which either Mendelian inconsistent trios are removed or Mendelian inconsistent markers are treated as missing genotypes, and the magnitude of the type I error increases both with an increase in sample size and with an increase in genotyping error rate. The results also show that a simple strategy, that is, merging each rare haplotype to a most similar common haplotype, can control the type I error inflation for a wide range of genotyping error rates, and after merging rare haplotypes, the power of the test is very similar to that without merging the rare haplotypes. Therefore, we conclude that a simple strategy may make the HS‐TDT robust to genotyping errors. Our simulation results also show that this strategy may also be applicable to other haplotype‐based TDTs. Genet. Epidemiol. © 2005 Wiley‐Liss, Inc.
Black liquor detoxification by laccase of Trametes versicolor pellets
Authors: Font Xavier , Caminal Gloria , Gabarrell Xavier , Romero Silvia , Vicent M Teresa 
Published: January 2005

AbstractBlack liquors from a soda pulping mill were treated with the white‐rot fungus Trametes versicolor to detoxify and reduce colour, aromatic compounds and chemical oxygen demand (COD). The fungus was used in the form of pellets in aerated reactors (fluidized, stirred and air‐pulsed reactors). Reductions in colour and aromatic compounds of 70–80% and in COD of 60% were achieved. During the different experiments, laccase activity was detected but neither lignin peroxidase (LiP) nor manganese peroxidase activities were detected, although T versicolor is able to produce these enzymes. Experiments also showed a LiP activity inhibitory effect produced by lignin. From the results obtained, it can be concluded that there is a relationship between laccase production and toxicity reduction. This correlation responds to the equation Laccase production = 1.57 LN (toxicity reduction) −16.40. Copyright © 2003 Society of Chemical Industry
Wet chemical synthesis of low bulk density aluminium hydroxide powder
Authors: Pradhan JK , Gochhayat PK , Bhattacharya IN , Das SC , Panda RK 
Published: January 2005

AbstractFine, low bulk density aluminium hydroxide powdered gel was prepared by the mild base hydrolysis of an aqueous solution of aluminium sulfate with hydrazine hydrate. Parameters such as method of addition of reactant, initial concentration of Al3+, mole ratio, final pH and hydrolysis temperature have a profound effect on the lightness and particle size of the powder. Optimized conditions showed that the final pH, Al3+ concentration and method of addition of reactant have a major contribution on the formation of lighter grade powder. Experiments conducted using other bases also produced lighter particles under similar conditions. Deviation from the optimized conditions led to formation of a higher bulk density product. Copyright © 2003 Society of Chemical Industry
Determination of the distribution of consolidants and interpretation of mercury porosimetry data in a sandstone porous network using LSCM
Authors: Zoghlami Karima , Gómez‐Gras David 
Published: January 2005

AbstractKnowing the 3D distribution of a consolidant within the porous network of a rock is essential for understanding the porosity quantitative data obtained by mercury porosimetry and for observing the effect of consolidants on pore interconnection. In this work, we show for the first time that the distribution of consolidant in the porous network can be determined using laser scanner confocal microscopy (LSCM). Results indicate that consolidants are concentrated in pore throats of less than 40 μm in diameter, affecting both the porous interconnection and the circulation of fluids. LSCM allowed demonstration of the fact that the increase in microporosity detected by mercury porosimetry is due to the development of fissures within the consolidants. No consolidant that produces this kind of fissure can be used in the consolidation of building stones, since it would increase microporosity and, in consequence, vulnerability to weathering agents. Microsc. Res. Tech. 65:270–275, 2004. © 2005 Wiley‐Liss, Inc.
New approach to quantifying developmental variation in the dentition using serial microtomographic imaging
Authors: Avishai Gal , Müller Ralph , Gabet Yankel , Bab Itai , Zilberman Uri , Smith Patricia 
Published: January 2005

AbstractDental morphogenesis and cellular differentiation are expressed in the fully formed tooth by the topography of the dentin–enamel junction and outer enamel surface. These boundaries can be differentiated using a variety of imaging systems. In this study, we used serial microCT imaging to provide accurate 3D reconstructions of developing lower human second deciduous molars. These were used to quantify the volume of enamel and dentin of individual cusps in relation to basal crown height. As growth and differentiation proceed apically, the spatial orientation of cusp tips and their bases were used to estimate their order of initiation and coalescence. We found that the order of coalescence differed from the order of initiation. We also found that dentin cusp height and volume as well as rate and quantity of enamel apposition varied along mesio‐distal and bucco‐lingual axes, and were independent of order of initiation and duration of growth. These results demonstrate that the potential for variation in crown size and form is maintained throughout development. We propose that the microCT model developed in this study constitutes a new approach for the investigation of developmental variation and its contribution to phylogenetic variation expressed in crown form and size. Microsc. Res. Tech. 65:263–269, 2004. © 2005 Wiley‐Liss, Inc.
Fabrication of Stable Chiral Polyaniline Nanocomposite‐Based Patterns
Authors: Yang Linglu , Yang Zhaohui , Cao Weixiao 
Published: January 2005

AbstractSummary: We report an artful method to form a stable pattern of chiral polyaniline nanocomposites (CPANs). It consists of the preparation of a diazoresin (DR)/poly(acrylic acid) (PAA) thin buffer layer on an Si substrate by self‐assembly, followed by the deposition of a multi‐layer film by spin‐assembly, leading to the formation of a (DR/PAA)2DR/(CPAN/DR)n film on the substrate. After selective exposure to UV light through a photomask and the development process, a defined pattern is formed.Scanning electron microscopy image of the patterned (CPAN/DR)5 thin film on Si wafer.imageScanning electron microscopy image of the patterned (CPAN/DR)5 thin film on Si wafer.
Numerical study of two‐dimensional stochastic NLS equations
Authors: Barton‐Smith Marc , Debussche Arnaud , Di Menza Laurent 
Published: January 2005

AbstractIn this article, we numerically solve the two‐dimensional stochastic nonlinear Schrödinger equation in the case of multiplicative and additive white noises. The aim is to investigate their influence on well‐known deterministic solutions: stationary states and blowing‐up solutions. In the first case, we find that a multiplicative noise has a damping effect very similar to diffusion. However, for small amplitudes of the noise, the structure of solitary state is still localized. In the second case, a local refinement algorithm is used to overcome the difficulty arising for the computation of singular solutions. Our experiments show that multiplicative white noise stops the deterministic blow‐up that occurs in the critical case. This extends the results of Debussche and Di Menza (Physica D, 162(3–4) 2002, 131–154) in the one‐dimensional case. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential, 2005.