bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement of properties of silica‐filled styrene‐butadiene rubber composites through plasma surface modification of silica
Authors: Mathew G. , Huh M.‐Y. , Rhee J. M. , Lee M.‐H. , Nah C. 
Published: June 2004

AbstractThe performance of plasma surface modified silica filler in styrene‐butadiene rubber (SBR) matrix has been analyzed. The conditions of plasma modification have been optimized by taking secant modulus as a standard parameter and the occurrence of the modification has been confirmed by surface area determination and Fourier transform infrared spectroscopy. The plasma‐modified surface of silica has been found to be composed of carbon–carbon double bonds and carbon–hydrogen bonds. Silane treatment also has been carried out on silica filler surface for a comparative assessment of its influence in the curing behavior and filler–rubber interaction. The cure reactions of all the rubber compounds have been found to be proceeded according to first‐order kinetics. A reduction in the cure reaction rate constant has been observed with the loading of unmodified and surface modified silica, emphasizing the cure deactivation of the matrix rubber by the silica filler. The filler dispersion, as revealed by scanning electron microscopy, has been found to be greatly improved by the plasma as well as silane treatment. The filler–rubber interaction has been found to be greatly improved by both surface treatments, but the best balance of mechanical properties has been observed with plasma surface modification only. Copyright © 2004 John Wiley & Sons, Ltd.
Low‐density polyethylene films doped with europium(III) complex: their properties and applications
Authors: Pogreb Roman , Finkelshtein Binyamin , Shmukler Yuri , Musina Albina , Popov Oleg , Stanevsky Oleg , Yitzchaik Shlomo , Gladkikh Alexander , Shulzinger Alexander , Streltsov Vladimir , Davidov Dan , Bormashenko Edward 
Published: June 2004

AbstractLight‐converting polyethylene film containing europium(III) complex with phenanthroline was manufactured under an extrusion process. The film was characterized first by means of time‐of‐flight secondary‐ion‐mass spectrometry (TOF‐SIMS), ultraviolet‐visible‐infrared (UV‐vis‐IR) spectroscopy, then a study of excitation and luminescence spectra, quantum yield and lifetime of luminescence. The quantum yield of luminescence was measured as 5±2%, and the lifetime of luminescence was determined about 470 μsec. TOF‐SIMS surface mapping showed the uniform distribution of europium(III) over the film. Visualization of strong picosecond UV laser beams through the use of the developed film has been demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.
Development of anti‐asparaginase antibodies in childhood acute lymphoblastic leukemia
Authors: Zalewska‐Szewczyk Beata , Andrzejewski Witalij , Bodalski Jerzy 
Published: June 2004

AbstractL‐asparaginase is a basic agent of antileukemic therapy, but allergic reactions against the drug and the development of anti‐asparaginase antibodies are significant side‐effects. The aim of our study was to estimate the presence of anti‐asparaginase antibodies and to correlate the results with clinically apparent allergic reactions and with L‐asparaginase activity during the treatment. We examined 13 children with newly diagnosed acute lymphoblastic leukemia (ALL), treated according to the Polish Pediatric Leukemia/Lymphoma Group protocol, based on ALL‐BFM 95. Enzyme activity was estimated in serum samples, collected before each L‐asparaginase administration, using the photometrical method. Anti‐asparaginase antibody concentration was measured by enzyme‐linked immunosorbent assay (ELISA) at the two time points: at the last day of L‐asparaginase treatment in the induction and the reinduction phase. The mean L‐asparaginase activity was 273 IU/L in the induction phase; no anti‐asparaginase antibodies in this phase of treatment were found. The mean L‐asparaginase activity was 425 IU/L in the reinduction phase of treatment; in five children anti‐asparaginase antibodies were detected. In four of these five children low L‐asparaginase activity and/or allergic reactions against L‐asparaginase were noted. Our observations suggest a correlation between the presence of anti‐asparaginase antibodies and L‐asparaginase activity in childhood ALL. © 2004 Wiley‐Liss, Inc.
Adenocarcinoma of the cervix and vagina in pediatric patients
Authors: McNall René Y. , Nowicki Philip D. , Miller Brigitte , Billups Catherine A. , Liu Tiebin , Daw Najat C. 
Published: June 2004

AbstractHere we report our combined analysis of vaginal mesonephric adenocarcinoma (MA) in a 13 years old treated at our institution and of reported vaginal or cervical MA and clear‐cell adenocarcinoma in 37 patients 18 years old or younger. Tumors in 27 patients arose in the vagina; 8 (21%) had metastases at diagnosis. The predominant symptom was vaginal bleeding; 62% of patients were exposed to diethylstilbestrol in utero. The 3‐year survival estimate was 71% ± 11%. Surgical treatment and metastasis at diagnosis were significant predictors of survival. The association between tumor excision and excellent outcome suggests that radical hysterectomy or pelvic exenteration is unnecessary. Radiotherapy as an adjunct may have contributed to this outcome. © 2004 Wiley‐Liss, Inc.
An NMR method towards the routine chiral determination of natural products
Authors: Jaki Birgit , Franzblau Scott , Pauli Guido F. 
Published: June 2004

AbstractState‐of‐the‐art structure elucidation and dereplication of natural products is incomplete without the determination of enantiomeric purity, especially when compounds are to be biologically evaluated. An NMR procedure is presented in order to distinguish and determine enantiomers in natural product samples. The method is also of value in the structure elucidation process by providing information, which is otherwise of a non‐routine nature. Using enantiomeric 1‐acetoxychavicol acetates and carvones as model compounds, this study presents a chiral NMR procedure that allows distinction and determination of chiral antipodes of natural products in a routine set‐up. Copyright © 2004 John Wiley & Sons, Ltd.
Supercritical carbon dioxide extraction of marigold at high pressures: comparison of analytical and pilot‐scale extraction
Authors: Baumann Dietmar , Adler Sven , Grüner Sabine , Otto Frank , Weinreich Bernd , Hamburger Matthias 
Published: June 2004

AbstractThe effects of pressure and co‐solvent on the extraction of anti‐inﬂammatory faradiol esters in marigold (Calendula ofﬁcinalis L.) were investigated by supercritical ﬂuid extraction at laboratory and pilot scales. Pressures higher than 300 bar and modiﬁer (ethanol) concentrations ranging from 0 to 20% (v/v) were used at an extraction temperature of 50 °C. With an analytical extractor, exhaustive extraction of the drug and highest concentrations in the extracts were achieved with 0.5% ethanol at the maximum pressure of 689 bar. Increased modiﬁer concentrations improved the extractability at lower pressure, but the higher amount of total extractables led to a lower concentration of faradiol esters in the extracts. The HPLC ﬁngerprints of the extracts, the yields of total extract and the concentration of faradiol esters obtained with analytical and pilot scale extractors under the same conditions were comparable. Copyright © 2004 John Wiley & Sons, Ltd.
The addition reaction of diamides to 1,2,5‐thiadiazole 1,1‐dioxide derivatives
Authors: Caram José A. , Mirífico María V. , Aimone Silvia L. , Piro Oscar E. , Castellano Eduardo E. , Vasini Enrique J. 
Published: June 2004

AbstractThe reactions of several derivatives of 1,2,5‐thiadiazole 1,1‐dioxide [3,4‐diphenyl‐(1a), 3,4‐bis(p‐methoxyphenyl)‐(1b), phenanthro[9,10‐c]‐(1c) and acenaphtho[1,2‐c]‐1,2,5‐thiadiazole 1,1‐dioxide (1d), 3,4‐diphenyl‐1,2,5‐thiadiazoline 1,1‐dioxide (2a) and 4‐ethoxy‐5‐methyl‐3,4‐diphenyl‐1,2,5‐thiadiazoline 1,1‐dioxide (2b)], with reagents possessing two nucleophilic nitrogen atoms (urea, N,N′‐dimethylurea, thiourea, N‐methylthiourea, N‐ethylthiourea, N‐allylthiourea, N,N′‐diethylthiourea, N,N′‐diphenylthiourea, dithioxamide and sulfamide), were followed by cyclic voltammetry (CV) and UV–visible spectrophotometry in aprotic solvent solution. The products were isolated, characterized by IR, 1H NMR and 13C NMR methods and their structure was confirmed by single‐crystal x‐ray diffraction. Several substrate–nucleophile combinations (1a–d and 2a with some ureas and thioureas) reacted to give good yields of new compounds formed by the addition reaction of the two nitrogen atoms of the nucleophile to the two >CN— double bonds of the 1,2,5‐thiadiazole 1,1‐dioxide ring. Some systems (1a–dithioxamide and 2b–thiourea) did not react, whereas in others (e.g. 1a–sulfamide) a monoaddition equilibrium reaction was observed. Copyright © 2004 John Wiley & Sons, Ltd.
Solid‐phase incorporation of gaseous carbon dioxide into oxirane‐containing copolymers
Authors: Ochiai Bungo , Iwamoto Tokinori , Miyagawa Toyoharu , Nagai Daisuke , Endo Takeshi 
Published: June 2004

AbstractCarbon dioxide was incorporated into poly(glycidyl methacrylate‐co‐methyl methacrylate) by a solid‐phase reaction, which transformed the pendent oxirane moieties into cyclic carbonate moieties, with quaternary ammonium halide catalysts. The incorporation of carbon dioxide into the copolymer led to soluble carbonate‐containing polymers, whereas the incorporation of carbon dioxide into the glycidyl methacrylate homopolymer produced an insoluble product. The copolymer composition, reaction temperature, and catalyst amount affected the incorporation efficiency and the side reaction that caused crosslinking. Effective incorporation was achieved under the following reaction conditions: the glycidyl methacrylate content was less than approximately 50%, the temperature was greater than the glass‐transition temperature, and the catalyst concentration was 1.5–6 mol %. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3812–3817, 2004
Integrated inherent safety index (I2SI): A tool for inherent safety evaluation
Authors: Khan Faisal I. , Amyotte Paul R. 
Published: June 2004

AbstractInherent safety is a proactive approach for loss prevention and risk management. Considering the lifetime costs of a process and its operation, an inherent safety approach can lead to a cost‐optimal option. Inherent safety may be achieved at any stage of process design; however, its application at the early stages of process design yields the best results. Despite being an attractive and cost‐effective approach, the inherent safety methodology is not widely used. Many reasons have been attributed to this lack of widespread use; the nonavailability of systematic tools for the application of inherent safety principles is perhaps the most important reason.This paper presents a conceptual framework of an integrated inherent safety index (I2SI). It is called an integrated index because the procedure, when fully developed, is intended to consider the life cycle of the process with economic evaluation and hazard potential identification for each option. The I2SI is composed of subindices which account for hazard potential, inherent safety potential, and add‐on control requirements. An application of the I2SI is also discussed. © 2004 American Institute of Chemical Engineers Process Saf Prog 23: 136–148, 2004
A major incident prevention program: Ten years of experience12
Authors: Renshaw Frank M. 
Published: June 2004

AbstractThis paper reviews one chemical company's experience in conducting Major Incident Prevention Program studies over the past 10 years in 90 bulk storage and processing units. The value and limitations of dispersion modeling, recurring findings from good practices and emergency response reviews, and dominant strategies for consequence and frequency reduction are outlined. The challenge and benefits posed by the use of quantitative criteria in evaluating and managing residual risk of ongoing operations are also discussed. © 2004 American Institute of Chemical Engineers Process Saf Prog 23: 155–162, 2004
One‐electron pseudopotential calculations of electronic properties of NaArn: Low‐energy isomers and absorption spectra
Authors: El Hadj Rhouma M. Ben , Berriche H. , Lakhdar Z. Ben , Spiegelman F. 
Published: June 2004

AbstractWe present a calculation of geometric structures and optical transitions in NaArn clusters. The energy of the system in its ground state is described using additive potentials with VNa‐Ar and VAr‐Ar representing the pair interactions. To find the geometry of the lowest‐energy isomers of NaArn clusters, we use the so‐called basin‐hopping method. The electronic structure of the metal valence electrons in the environment of the rare gas atoms is determined via a procedure close to the ab initio methodology involving e‐Na+ and e‐Ar semilocal pseudopotentials complemented by core polarization operators. The results shows that the absorption spectral features are sensitive to isomer structure. It is clearly the case for transitions close to the 3p levels of Na, which are distorted by the cluster environment. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Theoretical approach for simulation of femtosecond spectra: New strategies for optimal control of complex systems
Authors: Bonac̆ić‐Koutecký V. , Mitrić R. , Hartmann M. , Pittner J. 
Published: June 2004

AbstractWe present the ab initio Wigner distribution approach for simulation of femtosecond pump–probe and pump–dump signals and the new strategy for tailoring the light pulses that allow for optimal control of ultrafast processes. Our ab initio Wigner distribution approach combines the Wigner–Moyal representation of the vibronic density matrix with the ab initio multistate adiabatic and nonadiabatic molecular dynamics “on the fly” involving ground and excited electronic states. This approach allows for accurate simulations of femtosecond signals based on analytic formulation for systems of moderate complexity taking into account all degrees of freedom. For this purpose the following items are needed: (1) temperature‐dependent ground‐state initial conditions; (2) an ensemble of trajectories for the investigation of the dynamics of the system either on the adiabatic electronic excited state or on both the excited and ground states through nonadiabatic coupling; and (3) either the cationic or neutral ground state for the probing step. The goal of optimal control of femtosecond processes is to tailor pump–dump pulses that drive the system via electronically excited state to the desired ground‐state objective with the maximal yield. For the multidimensional systems this is possible only if the connective pathway between initial state and the objective can be ensured and the optimal pathway can be found. We show that these requirements are fulfilled by introducing the concept of the intermediate target in the excited state. Its role is to select the appropriate parts of energy surfaces at the given time delay between the two pulses, allowing us to reach optimally the objective. We illustrate the scope of our approach on nonstoichiometric halide deficient NanFn−1 clusters, which are characterized by strong ionic bonding and one excess electron. The choice of the systems has been made to determine timescales of different processes in the excited states and apply the new strategy for optimal control. This involves the bond breaking leading to (1) periodic geometric rearrangements such as in the case of Na2F or (2) nonadiabatic radiationless decay through conical intersection between the first excited state and the ground state occurring for Na3F2. In the latter case we optimize and analyze the pump and dump pulses to drive the isomerization process in the Na3F2 cluster to the second isomer by suppressing radiationless transition through conical intersection. The shaped pump–dump pulses serve as guidance for the experimental work in progress. Population of one of the two isomers allows us to establish a molecular switch. Such bimodal type of behavior might provide a basic element for information storage. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Using simply contracted basis functions with the Lanczos algorithm to calculate vibrational spectra
Authors: Wang Xiao‐Gang , Carrington Tucker 
Published: June 2004

AbstractWe demonstrate that the combination of simply contracted basis functions and the Lanczos algorithm yields an extremely efficient method for computing vibrational energy levels. We discuss ideas and present some results for HOOH and CH4. The basis functions we use are products of eigenfunctions of reduced‐dimension Hamiltonians obtained by freezing coordinates at equilibrium. The basis functions represent the desired wave functions well yet are simple enough that matrix–vector products may be evaluated efficiently. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Theoretical vibrational spectra of organic ring compounds compared to experiment
Authors: Förner Wolfgang 
Published: June 2004

AbstractWe have studied vibrational infrared (IR) and Raman spectra of several organic ring compounds. These include first cyclobutanecarboxaldehyde (CBA) and cyclohexanecarboxaldehyde (CHA) using density functional theory (DFT) together with a Becke‐3 exchange and Lee–Yang–Parr correlation (B3LYP) functional. DFT in these systems gives a stable and low‐energy gauche‐axial (g‐ax) conformer for both of the molecules together with the experimentally found equatorial conformations. However, on the basis of comparison of the theoretical vibrational spectra of the conformational mixture at 300 K with experimental spectra, the presence of the g‐ax conformer could be ruled out because it would yield extra lines not present in the corresponding experimental spectra. Thus, we concluded that DFT yields properties related to energy derivatives such as minimum geometries and vibrational spectra in fair agreement with experiment, while total energy differencies are not trustworthy when they are small, especially if small linear dependencies in the atomic basis sets applied appear. However, in that case we found that Møller–Plesset perturbation theory of second order (MP2) applied to CBA has the same problems and even does not predict the absolute minimum on the potential hypersurface correctly. Therefore, we applied DFT also to biphenyle (BP) and terphenyle (TP). Again, in BP and TP DFT turned out to yield reliable structures that as far as the important torsional angle between the rings is concerned are even better than MP2. Also, the vibrational spectra are in fair agreement with experimental ones. In BP restricted Hartree–Fock (RHF), DFT and experimental IR spectra all show two intense absorptions around 700 cm−1, while MP2 gives only one intense absorption band in this region. DFT also reproduces the position of these two lines well. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Application of accurate MP2 energies for closed‐shell atoms in examinations of density functionals for 3d10 electron ions
Authors: Jankowski K. , Nowakowski K. , Słupski R. , Flores J. R. 
Published: June 2004

AbstractArguments are presented that accurate second‐order Møller–Plesset (MP2) energies, evaluated in calculations involving extensive radial and angular basis sets, followed by careful angular extrapolations (referred to as MP2/CA energies), provide reliable approximations to the correlation energies for the ground states of closed‐shell atomic systems. MP2/CA energies are calculated for the members of the Cu+ isoelectronic series (Cu+, Zn2+, Ge4+, and Kr8+), which belong to the simplest atomic system containing the 3d10 configuration. The most accurate ab initio correlation energies for a 28‐electron isoelectronic series are reported. To exemplify the applicability of the total nonrelativistic energies, obtained as a sum of these energies and accurate Hartree–Fock energies, in examinations of density functionals, density functional theory energies are calculated for various functionals and basis sets and compared with their MP2/CA counterparts. An evaluation of the performance of these functionals is presented. The impact of the limited basis set size on the energy results is estimated. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Extension of the molecular quantum defect orbital methodology to the calculation of intensities and lifetimes for vibronic transitions within electronic Rydberg series of NO
Authors: Velasco A. M. , Bustos E. , Martín I. , Lavín C. 
Published: June 2004

AbstractExpressions relating explicitly the radiative lifetimes of vibronic states to the electronic transition moment and the absorption oscillator strengths for spin‐allowed transitions have been developed for the first time within the molecular quantum defect orbital (MQDO) methodology. Application to the intensities of the γ(A2Σ+ ← X2Π), ε(D2Σ+ ← X2Π), and (D2Σ+ ← A2Σ+) bands of NO, which are known to be of relevance in atmospheric studies, has been made. The MQDO results are in excellent accord with the measurements available in the literature. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Nonlinear oscillations in the molecular dimer: Asymptotic solutions
Authors: Maximov S. G. , Kuzmenkov L. S. , Guardado Zavala J. L. 
Published: June 2004

AbstractNonlinear oscillations in the molecular dimer, composed of two monomers, are investigated, considering an arbitrary number of excitons in the system. The bosonic operators are used to describe the exciton dynamics, that leads to value of the radius of a Bloch sphere that differs from known results. The Hamiltonian of the system is used to reduce the system of equations of motion to a single nonlinear ordinary differential operator equation of the fourth order. Then, the energy of the system is involved in this equation as a parameter. The stability problem is investigated for different energy values. A bifurcation occurs for the energies E > −1/2p. The asymptotic quasiclassical solution for the case E > −1/2p is obtained. The solution contains the number of excitons as a parameter. The quantum solutions can be obtained from the classical solutions using the continual integral technique. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004