bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of monomer addition sequences on the properties of silicon‐containing copolyimides
Authors: Ren Li , Li GL , Shen Jiarui , Jia Demin 
Published: April 2005

AbstractA series of silicon‐containing copolyimides was synthesized by the reaction of 4,4′‐diaminodiphenylmethane (DDM) with 1,4‐bis(3‐aminopropyldimethylsilyl) benzene (BisB) and pyromellitic dianhydride (PMDA). The synthesis reactions of the copoly(amic acid)s were carried out by three different monomer addition sequences under different molar ratios of BisB to DDM. The results obtained show that the viscosity of the poly(amic acid) (PA) solution obtained by the addition sequence of DDM–PMDA–BisB is higher than those of the other two addition sequences (ie [DDM + BisB]–PMDA and BisB–PMDA–DDM) and decreases as the molar ratio of BisB to DDM increases. Copolyimides formed by different addition orders, but with the same BisB to DDM molar ratios, possess different properties, such as dielectric constant, water absorption and contact angle. All of these copolyimides were insoluble in common organic solvents such as N‐methyl‐2‐pyrrolidinone and tetrahydrofuran. Thermogravimetric analysis (TGA) show that the silicon‐containing copolyimides have excellent thermal properties and their decomposition temperatures for an 8 % weight loss decrease slightly as [BisB]/[DDM] increases. Copyright © 2005 Society of Chemical Industry
Characterization of the sorption of an anthranilate fungicide in soil using thermal analytical and mineralogical techniques
Authors: Kennedy Angela , Lopez‐Capel Elisa , Manning David AC , Wilkins Richard M 
Published: April 2005

AbstractThe sorption of pesticides to soil particles has implications for their distribution and fate in the soil environment. A batch equilibrium technique was used to investigate sorption of the fungicide AEC623892 to intact and hydrogen‐peroxide‐treated whole soils and several particle‐size fractions isolated from them. Sorption of AEC623892 to the soil as a whole was low. Kfoc values measured in the whole soils were 169.2 and 41.9 ml g−1 for Soil A and Soil B respectively. The highest values of Kfoc were measured in soil particle‐size fractions <53 µm (266.5 ml g−1 in the 2–20 µm fraction of Soil A; 471.9 ml g−1 in the 20–53 µm fraction of Soil B). Sorption was most irreversible in the 2–20 µm fractions. Overall, treatment of soil particle‐size fractions with hydrogen peroxide resulted in lower values of Kfoc (112.3 ml g−1 in Soil A whole soil and 30.9 ml g−1 in Soil B whole soil). In both soils, the maximum sorption among hydrogen‐peroxide‐treated samples was observed in the <2 µm fraction (166.6 and 311.0 ml g−1 for Soil A and Soil B, respectively). Investigation of the mineralogical composition of the soils suggested that the clay mineralogy (dominated by kaolinite and illite) is less likely to account for the differences in sorption observed than differences in the characteristics of the soil organic matter. Thermal analysis of the different soil fractions indicated that hydrogen peroxide treatment preferentially removed aliphatic fractions of organic matter, but had less effect on lignin‐like, aromatic fractions. Copyright © 2005 Society of Chemical Industry
Accurate vibrational spectra of methylpotassium using a hybrid CCSD(t)/b3LYP approach and a variational treatment
Authors: Gohaud Neil , Begue Didier , Pouchan Claude 
Published: April 2005

AbstractWe present the structural parameters and vibrational spectra of CH3K computed using a hybrid approach in which CCSD(T) equilibrium values and harmonic wavenumbers are coupled to B3LYP anharmonic cubic and quartic terms in the framework of our variational treatment recently developed and presented for CH3Li. The obtained results confirm the assignment of several observed bands but suggest some revision of experimental assignments, as well. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Quantum‐controlled NOT gate made of coupled polyacetylene chains
Authors: Vales Guimarães Paulo Henrique , E Silva Geraldo Magela 
Published: April 2005

AbstractTwo interacting polyacetylene chains are considered as a system for possible physical implementation of a quantum‐controlled NOT gate. The two mid‐gap level states of a pair of solitons on each chain act as the control and target qubits, respectively. The dynamics of these solitons is calculated using an extended SSH Hamiltonian. The time‐dependent Schrödinger equation and the equation of motion for the lattice displacements are numerically integrated. The energy levels of the system are controlled by impurities added to each chain and the interchain interaction. The dynamics of the system is analyzed under the application of an electric field, and its influence on the energy levels is determined. The quantum‐controlled NOT gate behavior is obtained by the correct configuration of impurities. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Relativistic Gaussian basis sets obtained with a polynomial version of the generator coordinate Dirac–Fock method: Ionization energies of some closed‐shell atomic systems
Authors: Haiduke R. L. A. , de Macedo L. G. M. , Barbosa R. C. , Morgon N. H. , da Silva A. B. F. 
Published: April 2005

AbstractThe purpose of this work is to analyze the relativistic Gaussian basis sets obtained with a recently developed polynomial version of the generator coordinate Dirac–Fock method. The atomic systems chosen to evaluate the basis sets are some alkaline earth and noble gas atoms: He, Be, Ne, Mg, Ar, and Ca. Hartree–Fock, relativistic, and electronic correlation contributions to the atomic total energy of the neutral and ionized atomic species were estimated using these relativistic Gaussian basis sets. The basis sets developed were able to attain energies that deviate at most by 0.47 and 0.65 mHartree, respectively, from numerical Hartree–Fock and Dirac–Fock–Coulomb results and are also competitive with fully optimized relativistic Gaussian basis sets of similar sizes. The electronic correlation energy contributions were obtained after two nonrelativistic calculations: a Hartree–Fock and a full quadratic configuration interaction, including single and double substitutions. The uncontracted basis sets obtained here along with polarization functions chosen to have equal exponents to selected functions already present in the original set were adequate in describing not only the neutral but also the highly ionized atomic species. The comparison of some calculated shell ionization energies with experimental results presented a maximum deviation of 3% (for a total of 15 ionization values ranging from 18 to 10,599 eV), reinforcing the quality of the basis sets developed in this work. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Is the vibrational optical activity of (R)‐[2H1, 2H2, 2H3]‐neopentane measurable?
Authors: Hug Werner , Haesler Jacques 
Published: April 2005

AbstractThe compound, (R)‐[2H1, 2H2, 2H3]‐neopentane, with its Td symmetric electron distribution, is the archetype of molecules that owe their chirality exclusively to an asymmetric distribution of the masses of their nuclei. It has nine rotamers, which fall into two classes, one where the interchange of hydrogen and deuterium nuclei leads to an identical rotamer, and one where it interconverts different rotamers. Ab initio computations show that individual rotamers have Raman optical activity (ROA) and vibrational circular dichroism (VCD) of the same size as ordinary chiral molecules. Dilution and cancelation for the experimentally accessible equilibrium mixture reduces ROA and VCD, but the simulation of spectra with realistic band shapes of the Voigt type shows that both remain measurable in the 700–1,400‐cm−1 range, where ROA and VCD have a close to mirror image appearance. In the CH‐ and CD‐stretch region, in contrast, the sign pattern of ROA and VCD is identical. This curious behavior appears to be a consequence of the differing influence of inertial contributions in the two spectral regions. If summed over all vibrations, ROA and VCD cancel neatly, as one expects from the Td symmetric electron distribution. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Subcellular compartmentalization of calcium‐dependent and calcium‐independent neutral proteases in brain
Authors: Baudry Michel , Dubrin Richard , Lynch Gary 
Published: April 2005

AbstractIn the present experiments, we studied the subcellular distribution of three types of extralysosomal, neutral proteolytic activities in rat telencephalon: (1) nonthiol proteases (NTP), (2) thiol proteases (TP), and (3) calcium‐activated thiol proteases (calpains I and II). Subcellular fractionation was performed by using conventional differential and sucrose‐gradient centrifugation techniques. The only significant proteolytic activity detected in crude homogenates could be assigned to calpain II, the high‐threshold calcium‐activated protease. Within the primary fractions prepared from the homogenates, the highest levels of calpain II were found in S3, or the soluble cytoplasmic fraction. Significant activity of the enzyme was also present in P2, the crude mitochondrial/synaptosomal fraction. In contrast, the specific activity of calpain I was greatest in P2 with somewhat lesser enzymatic activity in P1 and S3. Most of the calpain I in P2 was recovered after differential centrifugation through sucrose gradients and lysis of the resultant subfractions. In marked contrast, only a small percentage of the calpain II activity was recovered in the gradient bands. In all, calpain II appears to be predominantly localized in the soluble cytoplasmic compartment while the greatest concentrations of calpain I are found in the soluble components of small glial and neuronal processes (pinched off during homogenization) that constitute the P2 fraction.The highest specific activity of the calcium‐independent proteases was obtained in P3, a fraction essentially devoid of calpain, with a secondary peak in P2. Subfractionation of P2 revealed that calcium‐independent TP in P2 was associated with mitochondria while the calcium‐independent NTP was more uniformly distributed across myelin, synaptosomes, and mitochondria. In all cases, calcium‐independent neutral proteases proved to be associated with membranes to a far greater degree than the calpains.These results indicate that neutral proteases in brain are compartmentalized to a surprising degree and therefore are likely to be operating at different stages or aspects of extralysosomal protein degradation. The concentration of calpain I in the P2 fraction and synaptosomal subfractions provides a plausible explanation for the occurrence of partially digested structural proteins obtained in highly purified postsynaptic densities isolated from cerebral cortex.
Neurotensin receptor binding sites in monkey and human brain: Autoradiographic distribution and effects of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine treatment
Authors: Quirion Rémi , Welner Sharon , Gauthier Serge , Bédard Paul 
Published: April 2005

AbstractNeurotensin (NT) receptor binding sites were characterized and localized by using membrane binding assay and in vitro receptor autoradioraphy in monkey and human brain. Additionally, the effects of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) treatment on NT binding sites were investigated in monkey. [125I]Tyr3‐NT ([125I]NT) apparently binds to a single class of high‐affinity sites (Kd in nanomolar range) in both species. Ligand selectivity patterns strongly suggest that the structural requirement of both monkey and human brain NT receptors are very similar to those previously reported in other tissues, such as those of the rat brain and rat stomach. In monkey brain, [125I]NT binding sites are discretely distributed with high densities of sites found in the cingulate cortex, amygdala, hippocampus, ventral tegmental area, substantia nigra, and periaqueductal gray matter. A similar pattern is observed in the human brain. However, the laminar distribution of [125I]NT binding sites in cortex varies between monkey and human brain. In monkey brain, [125I]NT binding sites are mostly concentrated in deep cortical layers while the laminar distribution of NT sites changes with cortical areas in human brain.The densities of [125I]NT binding sites are markedly decreased in the caudate, putamen, and substantia nigra in MPTP‐treated monkeys. These results suggest strong interactions between NT and dopaminergic systems in both monkey and human brain tissues.
Characterization of corticotropin‐releasing factor receptor‐mediated adenylate cyclase activity in the rat central nervous system
Authors: Battaglia George , Webster Elizabeth L. , De Souza Errol B. 
Published: April 2005

AbstractWe report here that corticotropin‐releasing factor (CRF) stimulates adenylate cyclase activity in the rat central nervous system (CNS). In frontoparietal cortex homogenates, the stimulation by CRF was dependent on time, temperature, tissue protein concentration, and guanine nucleotides. The rank order of potency for CRF analogs and fragments in stimulating adenylate cyclase activity [(Nle21,38) rat CRF > rat CRF ⋍ acetyl ovine CRF (4–41) ⋍ alpha helical ovine CRF > ovine CRF >> ovine CRF (1–39) ⋍ ovine CRF (7–41)] was consistent with their affinities for CRF receptors in the brain and their relative potencies in stimulating pituitary adrenocorticotropic hormone secretion in vitro. The putative CRF receptor antagonist, alpha helical ovine CRF (9–41), did not stimulate adenosine 3′,5′‐cyclic monophosphate (cAMP) production but was able to attenuate the stimulation by various concentrations of rat CRF. The regional distribution of 125I‐Tyro‐ovine CRF binding (olfactory bulb > frontoparietal cortex ⋍ cerebellum ⋍ hypothalamus > striatum ≥ midbrain > hippocampus ≥ spinal cord) did not correspond with the regional degree of CRF receptor‐mediated stimulation of adenylate cyclase (frontoparietal cortex > olfactory bulb ≥ cerebellum > midbrain ≥ hippocampus > striatum ⋍ hypothalamus > spinal cord). In addition, marked differences were observed in the ability of forskolin to potentiate CRF‐stimulated cAMP production in the various brain areas examined. In summary, these data demonstrat that at least one of the second‐messenger systems mediating the effects of CRF in the CNS involves stimulation of cAMP production and provides further support for a neurotransmitter role for this neuropeptide in the brain. Significant differences in the regulation of CRF‐stimulated cAMP production and the disparity between CRF receptor number and receptor‐mediated adenylate cyclase activity in discrete regions of the rat CNS suggest that some populations of CRF receptors in the brain may be functionally coupled to alternative signal transduction mechanisms.
Pacemaker potentials of serotonergic dorsal raphe neurons: Contribution of a low‐threshold Ca2+ conductance
Authors: Burlhis Theresa M. , Aghajanian George K. 
Published: April 2005

AbstractNeurons of the dorsal raphe nucleus exhibit intrinsic pacemaker potentials (gradual interspike depolarizing ramps) enabling them to sustain spontaneous rhythmic activity in the absence of synaptic interactions. A depolarizing prepotential (PP) has been observed in these cells, which appears to trigger the spike toward the end of the pacemaker cycle. The purposes of this study, carried out in the rat dorsal raphe nucleus brain slice preparation, were to (1) determine the ionic nature of the PP, (2) investigate its time‐ and voltage‐dependent properties, and (3) investigate the possible modulation of the underlying conductance by the α1‐agonist phenylephrine and by serotonin (5‐HT), agents that modify dorsal raphe pacemaker activity. During intracellular recording under current clamp, PPs were completely and reversibly blocked by divalent cations indicating that Ca2+ carries a significant portion of the current causing the PPs. Ni2+ specifically inhibited the PP with no effect on high‐threshold (−40 mV) Ca2+ spikes or the Ca2+ activated K+ conductance in these neurons. Activation threshold for the PP was found to be approximately −60 mV. Priming by hyperpolarization allowed removal of inactivation (de‐inactivation) of the PP in a time‐ and voltage‐dependent manner, with maximal PPs accompanying hyperpolarizing pulses to −90 mV and the de‐inactivation beginning to occur between −65 and −75 mV. Single‐electrode voltage‐clamp experiments demonstrated a region of negative‐slope conductance between −60 and −50 mV, which corresponds to the range of PP activation. The results of this study are consistent with a lowthreshold Ca2+ conductance underlying the PP whose role is to enable the membrane potential to rebound to action potential threshold at the end of the pacemaker cycle; neither phenylephrine nor 5‐HT directly affected this inward current.
Selective methodologies for the synthesis of biologically active piperidinic compounds
Authors: Cossy Janine 
Published: April 2005

AbstractThe synthesis of optically active substituted piperidines has been achieved by using four different methodologies. The first one is an intramolecular nucleophilic displacement of activated alcohol moieties that was used to build up the piperidine ring of (−)‐prosophylline and (−)‐slaframine, and the second one is a ring‐closing metathesis of unsaturated amines which was employed in the synthesis of (+)‐sedamine and 4a,5‐dihydrostreptazoline. The third methodology is the α‐functionalization of N‐Boc piperidines which was particularly useful in the synthesis of argatroban, and the fourth one is a ring expansion of prolinols to 3‐chloropiperidines or 3‐hydroxypiperidines which was utilized to synthesize (−)‐paroxetine, (−)‐pseudoconhydrine, the piperidine ring of (−)‐velbanamine and (+)‐zamifenacin. © 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 5: 70–80; 2005: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20035
Reactions of ion‐pair intermediates of solvolysis
Authors: Tsuji Yutaka , Richard John P. 
Published: April 2005

AbstractThe detection during solvolysis of competing signature reactions such as the racemization of a chiral substrate, or the scrambling of oxygen isotopes at the leaving group serves as evidence for a stepwise mechanism that proceeds through a reversibly formed ion‐pair intermediate. We have examined these signature reactions and determined the relative rates of competing solvolysis, isomerization, and racemization reactions of neutral ring‐substituted 1‐phenylethyl derivatives. These data were used to define the relative rate constants for partitioning of carbocation–anion pairs between dynamic processes such as reorganization of the ion pair within a solvent cage, and migration of the leaving group anion from the “top” to the “bottom” face of the planar carbocation. We present here a well‐defined picture of the dynamics of these reactions in the mostly aqueous solvent of 50/50 (v/v) trifluoroethanol/water. A more complicated problem is the description of the changes in the reaction energy profiles for solvolysis, isomerization, and racemization reactions that occur as one destabilizes the carbocation intermediate of the stepwise reaction. We have examined the signature isomerization and racemization reactions of a ring‐substituted 1‐phenylethyl derivative that reacts by a “borderline” mechanism. We suggest that the signature isomerization reaction may in fact follow a concerted mechanism that bypasses the putative carbocation–anion pair intermediate. © 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 5: 94–106; 2005: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20038
Provider gender and moral reasoning: The politics of an “ethics of care”
Authors: Wertz Dorothy C. 
Published: April 2005

AbstractWomen constitute 35% of providers in genetics at the doctoral level. A survey of 682 geneticists in 19 nations showed that gender was the single most important determinant of ethical decision making. Women were less directive and more observant of patient autonomy than men. In the United States, women were twice as likely as men to accede to patient requests for prenatal diagnosis for sex selection. Women now constitute 30% of all medical students, about half of all obstetrical residents, and 94% of master's‐level genetic counselors. Evidence that women providers respond differently to some ethical problems suggests that in the future, as more women enter the field, provider‐patient relationships may become more egalitarian.
Nursing and genetic health care
Authors: Lea Dale Halsey , Williams Janet K. , Tinley Susan T. 
Published: April 2005

AbstractAdvances in DNA technology are leading to major developments in nursing practice in clinical genetics, including the creation of new roles for nurses who care for people with genetic conditions. Application of genetic information and testing is moving genetics into the mainstream of health care. Therefore, it is anticipated that nurses in all areas of practice will become involved in the provision of information about genetic testing and assisting individuals and families in decision making and adjustment to new genetic information. This article provides an overview of the profession of nursing which may be useful to genetic counselors in the development of collaborative relationships between the two professions.
The role of intracellular Ca2+ in the regulation of proteinase‐activated receptor‐2 mediated nuclear factor kappa B signalling in keratinocytes
Authors: Macfarlane Scott R , Sloss Callum M , Cameron Pamela , Kanke Toru , McKenzie Roderick C , Plevin Robin 
Published: April 2005

In this study, we examined the role of Ca2+ in linking proteinase‐activated receptor‐2 (PAR2) to the nuclear factor kappa B (NFκB) pathway in a skin epithelial cell line NCTC2544 stably expressing PAR2 (clone G).
In clone G, PAR2‐mediated NFκB luciferase reporter activity and NFκB DNA‐binding activity was reduced by preincubation with BAPTA‐AM but not BAPTA. Trypsin stimulation of inhibitory kappa B kinases, IKKα and IKKβ, was also inhibited following pretreatment with BAPTA‐AM.
BAPTA/AM also prevented PAR2‐mediated IKKα activation in cultured primary human keratinocytes.
The effect of BAPTA‐AM was also selective for the IKK/NFκB signalling axis; PAR2 coupling to ERK, or p38 MAP kinase was unaffected.
Pharmacological inhibition of the Ca2+‐dependent regulatory protein calcineurin did not inhibit trypsin‐stimulated IKK activity or NFκB‐DNA binding; however, inhibition of Ca2+‐dependent protein kinase C isoforms or InsP3 formation using GF109203X or the phospholipase C inhibitor U73122, respectively, reduced both IKK activity and NFκB‐DNA binding.
Mutation of PAR2 within the C‐terminal to produce a mutant receptor, which does not couple to Ca2+ signalling, but is able to activate ERK, abrogated NFκB‐DNA binding and IKK activity stimulated by trypsin.
These results suggest a predominant role for the InsP3/Ca2+ axis in the regulation of IKK signalling and NFκB transcriptional activation.

British Journal of Pharmacology (2005) 145, 535–544. doi:10.1038/sj.bjp.0706204