bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of butyltin measurements for seawater, tissue, and marine sediment samples
Authors: Stallard Martha O , Cola Susan Y , Dooley Carol A 
Published: January 2005

AbstractOptimized techniques for measuring butyltins at the sub‐part‐per‐trillion (ppb; 1:1012) level in seawater and at the part‐per‐billion (ppb; 1:109) level in tissues and sediments are presented. Purge and trap/hydride derivatization followed by atomic absorption (AA) detection was optimized to give better sensitivity than was previously attained for seawater, yielding environmental detection limits of 0.08–0.2 ng dm−3. Improvement in precision and reproducibility in measurement of butyltins in tissues and sediments was attained by adjustment of the concentration in an organic extract to minimize matrix effects and by use of internal standards. The tissues and sediments were homogenized and extracted with methylene chloride (CH2Cl2) after acidification. The butyltins in the organic layer were derivatized with hexylmagnesium bromide and analyzed by gas chromatography (GC) with a flame photometric detector (FPD). The absolute detection limits in tissues and sedimets were 0.1 ng for tributyltin (TBT), 0.12 ng for dibutyltin (DBT) and 0.29 ng for monobutyltin (MBT).
Entwurfsoptimierung von Verbau und Wasserhaltung tiefer, wasserdichter Baugruben in bindigen Böden
Authors: Moormann Christian 
Published: January 2005

AbstractAktuelle Ausführungsbeispiele tiefer Baugruben in bindigen Böden zeigen, daß bei heute häufig als Regellösung Anwendung findenden, wasserdichten Baugrubenumschließungen die Erd‐ und Wasserdrucklasten mit zunehmender Baugrubentiefe so stark anwachsen, daß im Hinblick auf die aufzunehmenden Stützkräfte, die statisch erforderliche Einbindetiefe und die Biegemomentenbeanspruchung der Verbauwände sehr aufwendige Konstruktionen erforderlich werden und daß dabei – insbesondere bei tiefen, rückverankerten Baugruben – oft die Grenze der Ausführbarkeit erreicht wird. In diesen Fällen ist eine wasserdichte Verbauwandausführung nur möglich, wenn es gelingt, die großen Einwirkungen aus Wasserdruck und Strömungskräften zu reduzieren. In dem Beitrag werden Ansätze für eine Optimierung von Grundwasserhaltung und Verbaugestaltung tiefer, wasserdichter Baugruben in bindigen, durchlässigkeitsanisotropen Böden durch eine Reduktion der Wasserdruckbeanspruchung des Verbaus vorgestellt. Es werden Lösungsansätze zur Reduktion der Wasserlast durch eine Teil auflösung des Verbaus unterhalb der Baugrubensohle sowie durch Entspannungslanzen untersucht, vereinfachte Bemessungsansätze abgeleitet und Hinweise zur Entwurfsoptimierung formuliert.
Untersuchung zur Erddruckbeanspruchung von Winkelstützwänden
Authors: Achmus Martin , Rouili Ahmed 
Published: January 2005

AbstractDie Bemessung des vertikalen Schenkels von Winkelstützwänden ist gemäß derzeitiger deutscher Normung für erhöhten Erddruck, d. h. den Mittelwert aus aktivem Erddruck und Erdruhedruck, vorzunehmen. Dieser Ansatz liegt, wie im vorliegenden Aufsatz gezeigt wird, in vielen Fällen deutlich auf der sicheren Seite. Mittels einer numerischen Parameterstudie werden die wesentlichen Einflußfaktoren aufgezeigt. Auf der Grundlage der Ergebnisse wird ein Verfahren vorgeschlagen, das die genauere Festlegung der Erddrucklast unter Berücksichtigung der wesentlichen Einflußgrößen in einfacher Weise ermöglicht.
Decision‐making competence: External validation through an individual‐differences approach
Authors: Parker Andrew M. , Fischhoff Baruch 
Published: January 2005

AbstractThis study asks to what extent (a) individuals show consistent performance differences across typical behavioral decision‐making tasks, and (b) how those differences correlate with plausible real‐world correlates of good decision making. Seven tasks, chosen to span the domain of decision‐making skills, were administered to participants in an ongoing longitudinal study providing extensive social, psychological, and behavioral measures. Performance scores on individual tasks generally showed small, positive inter‐task correlations. An aggregate measure of decision‐making competence (DMC) was appropriately correlated with plausible sources, concomitants, and outcomes of good decision making, suggesting the underlying construct's external validity. Higher DMC scores were associated with more intact social environments, more constructive cognitive styles, and fewer ‘maladaptive’ risk behaviors. In each case, DMC adds to the predictive validity of general measures of cognitive ability. These results suggest that poor decision making on common laboratory tasks is related to real‐world antecedents and consequences of poor decision making. Copyright © 2005 John Wiley & Sons, Ltd.
Structural and dynamic consequences of increasing repeats in a MUC1 peptide tumor antigen
Authors: Schuman Jason T. , Grinstead Jeffrey S. , Apostolopoulos Vasso , Campbell A. Patricia 
Published: January 2005

AbstractMUC1 mucin is a large transmembrane glycoprotein whose extracelluler domain is composed of repeating units of a 20 amino acid sequence. In the cancer associated state, this protein expression becomes upregulated and underglycosylated. Previous studies, which show an enhanced binding of a 5‐repeat over a 1‐repeat MUC1 peptide to a panel of anti‐MUC1 antibodies, have led us to investigate the structural and dynamic consequences of increasing repeat number. Two MUC1 peptides were studied: a 16mer corresponding to slightly less than one full repeat of the MUC1 tandem repeat sequence (GVTSAPDTRPAPGSTA) and a 40mer corresponding to two full repeats of the MUC1 sequence (VTSAPDTRPAPGSTAPPAHG)2. Isotopically labeled versions of these MUC1 peptides were cloned, expressed, purified, and evaluated structurally and dynamically using 15N‐ and 13C‐edited NMR approaches. The data show that MUC1 structure, dynamics, and antibody binding affinity are invariant with increasing repeat number. In light of these results, we conclude that the enhanced antibody affinity of the 5‐repeat over the 1‐repeat MUC1 peptide is due to multivalency effects, and not due to the development of higher order structure in the longer length peptides. The implications of these results are discussed within the context of a multiple repeat MUC1 breast cancer vaccine design. © 2005 Wiley Periodicals, Inc. Biopolymers, 2005
Systematic review of hyperbaric oxygen in the management of chronic wounds
Authors: Roeckl-Wiedmann I , Bennett M , Kranke P 
Published: January 2005

AbstractBackgroundMany therapeutic options exist for chronic wounds. Hyperbaric oxygen therapy (HBOT) is one such option. It may be used for diabetic, venous, arterial and pressure ulcers.MethodsFollowing a systematic search of the literature, pooled analyses of predetermined clinical outcomes of randomized controlled trials involving the use of HBOT for chronic wounds were performed. Relative risks (RR) and number needed to treat (NNT) with 95 per cent confidence intervals (c.i.) were calculated.ResultsSix studies met the inclusion criteria. No appropriate trials were located for arterial and pressure ulcers. Pooled data from five trials on diabetic ulcers (118 patients) suggested a significant reduction in the risk of major amputation with HBOT (RR: 0·31; c.i. 0·13 to 0·71) with a NNT of 4 (c.i. 3 to 11). Sensitivity analyses did not alter the results. Ulcer healing and the rate of minor amputation were not influenced by HBOT. Data from one trial on venous ulcers suggested significant wound size reduction at the end of the treatment, but not at follow-up.ConclusionsThere is evidence that HBOT reduces the risk of major amputation in diabetic patients. For venous, arterial or pressure ulcers there is a lack of data. Further trials may be warranted.
Radical Cations of Phenyl‐Substituted Aziridines: What Are the Conditions for Ring Opening?
Authors: Gaebert Carsten , Mattay Jochen , Toubartz Marion , Steenken Steen , Müller Beat , Bally Thomas 
Published: January 2005

AbstractRadical cations were generated from different phenyl‐substituted aziridines by pulse radiolysis in aqueous solution containing TlOH.+, N3.or SO4.−as oxidants or inn‐butyl chloride, by60Co γ radiolysis in Freon matrices at 77 K, and in some cases by flash photolysis in aqueous solution. Depending on the substitution pattern of the aziridines, two different types of radical cations are formed: if the N atom carries a phenyl ring, the aziridine appears to retain its structure after oxidation and the resulting radical cation shows an intense band at 440–480 nm, similar to that of the radical cation of dimethylaniline. Conversely, if the N atom carries an alkyl substituent while a phenyl ring is attached to a C‐atom of the aziridine, oxidation results in spontaneous ring opening to yield azomethine ylide radical cations which have broad absorptions in the 500–800 nm range. In aqueous solution the two types of radical cations are quenched by O2with different rates, whereas inn‐butyl chloride, the ring‐closed aziridine radical cations are not quenchable by O2. The results of quantum chemical calculations confirm the assignment of these species and allow to rationalize the different effects that phenyl rings have if they are attached in different positions of aziridines. In the pulse radiolysis experiments in aqueous solution, the primary oxidants can also be observed, whereas inn‐butyl chloride a transient at 325 nm remains unidentified. In the laser flash experiments, both types of radical cations were also observed.
Deep‐seated, well differentiated lipomatous tumors of the chest wall and extremities
Authors: Bassett Mikelle D. , Schuetze Scott M. , Disteche Christine , Norwood Thomas H. , Swisshelm Karen , Chen Xiaoqin , Bruckner James , Conrad Ernest U. , Rubin Brian P. 
Published: January 2005

AbstractBACKGROUNDIntramuscular lipomas and atypical lipomatous tumors (ALT) are common deep‐seated lipomatous tumors of the chest wall and extremities. Distinguishing between these two entities can be difficult based on histologic analysis alone. However, the cytogenetic profiles of ALT and intramuscular lipomas are distinct. Correct classification is important, because aggressive local disease recurrence occurs more frequently in patients with ALT than in patients with intramuscular lipoma. The authors examined their single institutional experience and correlated their classification with clinical features and outcome.METHODSIn the current study, 106 patients with deep‐seated, well differentiated adipose tumors of the chest wall and extremities were classified as having ALT or intramuscular lipoma using a combined approach of histology and cytogenetics, if available. The classification was correlated with clinicopathologic features and follow‐up data.RESULTSFifty‐five patients were classified as having intramuscular lipoma and 51 were classified as having ALT. Classification did not correlate with age and gender (P = 0.28 and P = 0.96, respectively). Intramuscular lipomas were smaller than ALTs (P < 0.0001), but there was significant overlap between the 2 groups. ALT occurred preferentially in the lower extremity (P < 0.0009). Four percent of patients with intramuscular lipomas and 27% of patients with ALTs developed local disease recurrence (P = 0.0006). Disease recurrence did not correlate with patient age at diagnosis, patient gender, tumor size, and tumor location (P = 0.45, P = 0.26, P = 0.49, and P = 0.28, respectively). Within the subset of patients with ALTs, disease recurrence did not correlate with patient age at diagnosis, patient gender, or tumor location (P = 0.38, P = 0.54, and P = 0.86, respectively).CONCLUSIONSClassification of deep‐seated, well differentiated lipomatous tumors of the extremities and chest wall using a combined approach of histology and cytogenetics correlated well with biologic behavior/disease recurrence. This combined approach is advocated to better stratify patients for treatment purposes and follow‐up. Cancer 2005. © 2004 American Cancer Society.
A pseudopotential SCF‐MO study of Te
Authors: Rothman Michael J. , Bartell Lawrence S. , Ewig Carl S. , Van Wazer John R. 
Published: January 2005

AbstractA recently developed ab initio pseudopotential molecular orbital approach was applied to the Te ion, a system outside the practical reach of conventional all‐electron treatments. Computations were carried out with a minimal STO‐4G basis set. Results account reasonably well for the observed optical absorption spectrum and suggest the origin of a hitherto unassigned weak band. Ground‐state properties, which included the structure, force field, and vibrational frequencies, were also investigated. Treated as a free, gas‐phase ion, tetratellurium (II) yielded a bond length 0.05 Å shorter than the experimental value for the ion in a crystal lattice. Placement of static, point‐charge counterions in the Te coordination sphere increased the bond length to a value 0.005 Å longer than derived by experiment. Calculations on neutral, cyclic Te4 provided a theoretical single‐bond reference length 0.09 Å longer than that obtained for the ion in a counterion environment. Comparisons between observed and calculated frequencies suggest an assignment of the vibrational spectrum different from the provisional assignment in the literature.
Integrated spatial electron populations in molecules: Application to simple molecules
Authors: Collins John B. , Streitwieser Andrew 
Published: January 2005

AbstractThe electron projection function P(x, z) = ∫ ρ(x, y, z) dy is used to evaluate charge transfer and covalency in two series of molecules, LiX and CH3X (X = Li, BeH, BH2, CH3, NH2, OH, and F), with wavefunctions derived from STO‐3G, 4‐31G, and, in some cases, 6‐31* ab initio calculations. The precision of the method and comparison with Mulliken populations analysis are described. Particular attention is given to CH3Li which by our criteria is wholly ionic.
Microcomputer‐aided instruction and research in group theory
Authors: Trindle Carl 
Published: January 2005

AbstractA collection of programs which aid in the use of group theory has been developed for the Apple II. The programs automate much of the tedious algebra necessary to generate character tables and representation matrices from the properties of the operators chosen to generate the group. At the same time, the presentation of intermediate results provides a schematic guide to the procedures by which groups are constructed. The choice of generators is not limited to the reflections, rotations, and inversions, which are the familiar features of chemical group theory. Any generator representable as a permutation may be treated; thus general permutation groups and Longuet‐Higgins groups may be studied. As an illustration we describe the states of beryllium borohydride, which require a form of Longuet‐Higgins group theory.
Treatment of multiexponential decay data by the method of zero determinants
Authors: Szamosi Janos , Schelly Z. A. 
Published: January 2005

AbstractThe principles of a new method, the method of zero determinants, are described which can be used for the determination of the number of exponentials in accurate, multiexponential decay curves, as well as for the smoothing of multiexponential experimental data. It is based on the idea that the determinant of an overdetermined data matrix for accurate data is zero. The method is not limited by mathematical approximations, and thus uncovers the decay curve hidden in the data set.
A theoretical study on the protonation of cycloalkanes CnH2n (n = 3 to 6)
Authors: Lee Choi Chuck , Hass Ernst C. , Obafemi Craig A. , Mezey Paul G. 
Published: January 2005

AbstractAb initio self‐consistent‐field molecular orbital calculations have been carried out for the CnH2n (n = 3 to 6) cycloalkanes and various conformers of their protonated forms. The calculated protonation energies for the sequence of conformers of the protonated forms follow the experimentally observed trend. Correlations between optimum CCC bond angles at the protonation site and the calculated protonation energies have been observed, and these correlations may be of some use in estimating protonation energy‐bond angle relations in other (strained) cyclic compounds when the central carbon atom of a CCC moiety is protonated.
Reliable Gaussian basis sets for closed‐shell atoms
Authors: Radzio Elżbieta , Andzelm Jan 
Published: January 2005

AbstractMedium size Gaussian basis sets for inert‐gas atoms (from neon to xenon) have been constructed using the energy optimization method which maintains reliable description of the long‐range valence atomic region. These basis sets have been tested in SCF calculations on homonuclear inert‐gas dimers. For Ne2, Ar2, and Kr2, the present results have been analyzed carefully and compared with those obtained using extended basis sets (for Kr2 extended benchmark calculations are also reported). Our interation energies agree well with accurate values and are compared with experimental data. For Ne2 and Ar2, detailed studies of basis set superposition error also are presented.
Quantum mechanical modeling of a transannular interaction in a bicyclic amidinium ion
Authors: Edwards W. Daniel , Weisman Gary R. 
Published: January 2005

AbstractA transannular donor‐acceptor interaction in a bicyclic azaamidinium salt was modeled by quantum mechanical calculations using a supermolecule complex consisting of a formamidinium cation and an ammonia molecule. Molecular properties are reported at various geometries. These results are compared with the results of similar calculations on the bicyclic cation itself. The model calculations and the bicyclic cation calculations are in good agreement, but both fail to reproduce the experimentally known structure. Results from ab initio calculations on the model system are discussed, as are results from calculations which included iodide as counterion.
Molecular mechanics and the deformation of macromolecules: The use of a very short cutoff combined with a quadratic approximation
Authors: Karfunkel H. R. 
Published: January 2005

AbstractAn approximation to the molecular mechanical treatment of structural deformations of macromolecules is presented. The method is based on a partitioning of the conformational energy into three parts. The first part is covered by the condensed potential functions which absorb many short‐range nonbonding interactions. The second part consists of a few nonbonded interactions below a very short cutoff radius of 4 Å. The third part, consisting of the vast majority of pairwise interactions, is approximated by a quadratic expression confined to a subspace of the conformational space. A detailed computational example on LH‐RH, including an analysis of the errors resulting from other conventional approximation methods, is given. A comparison to the conventional cutoff approximation used in x‐ray refinement delivers a speedup factor of at least two orders of magnitude.
The MMP2 calculational method
Authors: Sprague Joseph T. , Tai Julia C. , Yuh Young , Allinger Norman L. 
Published: January 2005

AbstractThe molecular mechanics (MMP2) program and procedures for the treatment of conjugated hydrocarbons, and some of the results which they can achieve are described. The program is an updated version of the similar MMP1 program, but contains some differences. It is based on an SCF π system calculation, rather than on the VESCF method used earlier. All parameters are compatible with those in the MM2 program. Hence it is possible to calculate heats of formation, resonance energies, and structures for conjugated hydrocarbons in a way that is consistent with the calculations on non‐conjugated molecules. The overall results as far as structure and energy are somewhat better than they were with the MMP1 program.
Configurational specificity of stacking interactions in DNA base pairs: A computational analysis
Authors: Sanyal Nitish K. , Roychoudhury M. , Ruhela Kavita R. , Tiwari Sugriva Nath 
Published: January 2005

AbstractA theoretical study of stacking patterns of various hydrogen‐bonded base pair complexes has been undertaken. Modified Rayleigh‐Schrodinger perturbation theory for intermediate range interactions, has been employed to evaluate the stacking interactions using multicentered‐multipole expansion method. Net atomic charge and corresponding dipole components located at each of the atomic centers have been computed by CNDO/2 method. An analysis of the intermolecular forces involved in the stable formation of the various base pair complexes, has been presented and the results have been discussed in the light of experimental as well as other theoretical observations. The possibility of relative preference of the left‐handed configuration for alternating sequences has been quantitatively explored.
Algorithm for rapid calculation of Hessian of conformational energy function of proteins by supercomputer
Authors: Wako Hiroshi , Gō Nobuhiro 
Published: January 2005

AbstractAn improved algorithm is presented for rapid calculation of the hessian matrix for the conformational energy of a protein as a function of only dihedral angles. The speed of the calculation, which is about one order faster than by the previous method, is achieved by two considerations. First, the algorithm is designed to take advantage of the supercomputer pipeline architecture. Second, long‐range, nonbonded interactions are cut off and long‐range electrostatic interactions are approximated by dipole‐dipole interactions in order to reduce the number of pairwise interactions that have to be computed. The results of benchmark tests of the program are given as applied for four globular proteins of different sizes.
Strategies for vectorizing the sparse matrix vector product on the CRAY XMP, CRAY 2, and CYBER 205
Authors: Bauschlicher Charles W. , Partridge Harry 
Published: January 2005

AbstractLarge randomly sparse matrix vector products are important in a number of applications in computational chemistry, such as matrix diagonalization and the solution of simultaneous equations. Vectorization of this process is considered for the CRAY XMP, CRAY 2, and CYBER 205, using a matrix of dimension of 20 000 with from 1% to 6% nonzeros. Efficient SCATTER/GATHER capabilities add coding flexibility and yield significant improvements in performance. For the CYBER 205, it is shown that minor changes in the IO can reduce the CPU time by a factor of 50. Similar changes in the CRAY codes make a far smaller improvement.
A specific inhibitor design approach by means of molecular dynamics calculation for porcine pancreatic elastase
Authors: Fujita T. 
Published: January 2005

AbstractA 27‐picosecond (ps) molecular dynamics calculation has been carried out for the 1:2 enzyme‐ligand complex between porcine pancreatic elastase (PPE) and acetyl‐alanine‐proline‐alanine (APA). A data analysis has been carried out using a total of 450 structures. During the simulation, the root‐mean‐square fluctuations (RMSF) increased compared with the x‐ray data. Some differences of the hydrogen bond arrangement in the MD average structures are found especially for SER 195, suggesting the fluctuations of the ligand molecules. The radius of gyration decreased a little during the simulation. Although intermolecular hydrogen bonds between two substrates (APA1 and APA2) has not been found by a 1.65‐Å high‐resolution x‐ray diffraction study, the MD calculation showed the intermolecular hydrogen bond between them to be 3.2 Å. The extended active site of PPE is so wide compared with the size of a tripeptide that such a hydrogen‐bound hexapeptide can be more specific than tripeptides, which is consistent with the kinetic data previously reported.