bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Three‐State Model for the Photophysics of Adenine
Authors: Serrano‐Andrés Luis , Merchán Manuela , Borin Antonio Carlos 
Published: June 2006

AbstractAn ab initio theoretical study at the CASPT2 level is reported on minimum energy reaction paths, state minima, transition states, reaction barriers, and conical intersections on the potential energy hypersurfaces of two tautomers of adenine: 9H‐ and 7H‐adenine. The obtained results led to a complete interpretation of the photophysics of adenine and derivatives, both under jet‐cooled conditions and in solution, within a three‐state model. The ultrafast subpicosecond fluorescence decay measured in adenine is attributed to the low‐lying conical intersection (gs/ππ* La)CI, reached from the initially populated 1(ππ* La) state along a path which is found to be barrierless only in 9H‐adenine, while for the 7H tautomer the presence of an intermediate plateau corresponding to an NH2‐twisted conformation may explain the absence of ultrafast decay in 7‐substituted compounds. A secondary picosecond decay is assigned to a path involving switches towards two other states, 1(ππ* Lb) and 1(nπ*), ultimately leading to another conical intersection with the ground state, (gs/nπ*), with a perpendicular disposition of the amino group. The topology of the hypersurfaces and the state properties explain the absence of secondary decay in 9‐substituted adenines in water in terms of the higher position of the 1(nπ*) state and also that the 1(ππ* Lb) state of 7H‐adenine is responsible for the observed fluorescence in water. A detailed discussion comparing recent experimental and theoretical findings is given. As for other nucleobases, the predominant role of a ππ*‐type state in the ultrafast deactivation of adenine is confirmed.
Synthesis and Stereochemical Assignment of DNA Spore Photoproduct Analogues
Authors: Friedel Marcus G. , Pieck J. Carsten , Klages Jochen , Dauth Christina , Kessler Horst , Carell Thomas 
Published: June 2006

AbstractInvestigation of the DNA repair process performed by the spore photoproduct (SP) lyase repair enzyme is strongly hampered by the lack of defined substrates needed for detailed enzymatic studies. The problem is particularly severe because the repair enzyme belongs to the class of strongly oxygen‐sensitive radical (S)‐adenosylmethionine (SAM) enzymes, which are notoriously difficult to handle. We report the synthesis of the spore photoproduct analogues 1 a and 1 b, which have open backbones and are diastereoisomers. In order to solve the problem of stereochemical assignment, two further derivatives 2 a and 2 b with closed backbones were prepared. The key step of the synthesis of 2 a/b is a metathesis‐based macrocyclization that strongly increases the conformational rigidity of the synthetic spore photoproduct derivatives. NOESY experiments of the cyclic isomers furnished a clear cross‐peak pattern that allowed the unequivocal assignment of the stereochemistry. The results were transferred to the data for isomers 1 a and 1 b, which were subsequently used for enzymatic‐repair studies. These studies were performed with the novel spore photoproduct lyase repair enzyme from Geobacillus stearothermophilus. The studies showed an accordance with a recent investigation performed by us with the spore photoproduct lyase from Bacillus subtilis,1 in that only the S isomer 1 a is recognized and repaired. The ability to prepare a defined functioning substrate now paves the way for detailed enzymatic studies of the SP‐lyase lesion recognition and repair process.
Feuerwiderstand von hoch belasteten schlanken Ziegelwänden
Authors: Meyer Udo 
Published: June 2006

AbstractZiegelmauerwerk hat erfahrungsgemäß einen hohen Feuerwiderstand. Durch aktuelle Untersuchungen im Auftrag der Arbeitsgemeinschaft Mauerziegel wurde nachgewiesen, daß die höchste bauaufsichtliche Anforderung “feuerbeständig” (F 90/REI 90) auch für die erhöhten Belastungen nach DIN 1053‐100 weiterhin sicher durch die Verwendung von beidseitig verputzten, 115 mm dicken Wänden aus HLzB6‐0,8 nach DIN V 105‐2 ein.
A Supramolecular Assembly of Organotin Complexes: Syntheses, Characterization and Crystal Structures of Organotin Complexes with meso‐2,3‐Dimercaptosuccinic Acid
Authors: Ma Chunlin , Zhang Qingfu 
Published: June 2006

AbstractA series of two types of organotin complexes, namely [(R3Sn)4(dmsa)] (R = Ph 1, PhCH2 2, CH3 3, nBu 4; H4dmsa = meso‐2,3‐dimercaptosuccinic acid) and [(R2Sn)2(dmsa)(Y)]·L (R = Ph, Y = 2H2O, L = H2O, Et2O 5; R = PhCH2 6; R = CH3 7; R = nBu 8; R = nBu, Y = 0.5MeOH 9) have been synthesized. All complexes were characterized by elemental analysis and FT‐IR and NMR (1H, 13C and 119Sn) spectroscopy. Among them, the strucrtures of complexes 1, 3, 5, and 9 were also determined by X‐ray crystallography. The structural analyses show that complexes 1 and 3 are tetranuclear triorganotin monomers, complex 5 is a dinuclear diphenyltin monomer, and complex 9 is a 3D di‐n‐butyltin coordination polymer with a metal‐organic framework structure. The supramolecular structure analyses reveal that the type of organic substituent attached to the tin atoms can apparently affect the supramolecular assembly: when the substituents attached to the tin atom are aromatic groups (1 and 5) the supramolecular structures are dominated by intermolecular π–π (C–H···π) weak interactions, whereas when the substituents attached to the tin atom are alkyl groups (3 and 9) the supramolecular structures are dominated by intermolecular Sn←X (X = S, O) coordination interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthesis of Epibatidine‐Related Δ2‐Isoxazoline Derivatives and Evaluation of Their Binding Affinity at Neuronal Nicotinic Acetylcholine Receptors
Authors: Dallanoce Clelia , Bazza Paola , Grazioso Giovanni , De Amici Marco , Gotti Cecilia , Riganti Loredana , Clementi Francesco , De Micheli Carlo 
Published: June 2006

AbstractThe group of Δ2‐isoxazoline derivatives5a–cand6a–c, structurally related to epibatidine, and the simplified analogues7a–cwere synthesized by means of a 1,3‐dipolar cycloaddition‐based strategy and tested at α4β2 and α7 neuronal acetylcholine receptor (nAChR) subtypes. Competition binding experiments at α4β2 nAChR subtypes showed an overall significant reduction in affinity for the compounds under study in comparison to the reference radioligand [3H]‐epibatidine. These outcomes have been rationalized by taking into account the ligand‐based pharmacophore models reported in the literature and the recently proposed molecular model of the α4β2 receptor subtype. Conversely, compounds5b,5c, and6bexhibited a noticeable affinity for the α7 receptors and, in the case of5c, also some subtype selectivity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Mathematical model for hydrodistillation of essential oils
Authors: Sovová Helena , Aleksovski Slavcho A. 
Published: June 2006

AbstractHydrodistillation of essential oils was studied using a model with broken and intact cells, in which the solute located in the cells with broken walls is rapidly extracted and the solute from intact cells diffuses slowly to the surface of botanical material. The essential oil is regarded as a pseudo‐component. Model equations describe two types of particles: the leaves, where a part of the solute is deposited on the surface in fragile glandular trichomes, and the ground particles, with initially homogeneous solute distribution. Analytical solution of model equations contains two time constants, the larger one related to essential oil diffusion from the particle core. Using literature data, the model was applied to hydrodistillation of creeping thyme leaves and intact coriander seeds. The effective diffusivity of oil in coriander seed was evaluated as 1.7 × 10−11[sol ]m2[sol ]s. A further model development should respect the different volatilities of essential oil components, leading to changes in the distilled oil composition in the course of the process. Copyright © 2006 John Wiley & Sons, Ltd.
Early caspase‐3 activation independent of apoptosis is required for cellular function
Authors: Rosado Juan A. , Lopez Jose J. , Gomez‐Arteta Emilio , Redondo Pedro C. , Salido Gines M. , Pariente Jose A. 
Published: June 2006

AbstractA number of pro‐apoptotic stimuli induce the activation of caspase‐9, an initiator protease that activates executioner caspases, such as caspase‐3, leading to the development of programmed cell death. Here we demonstrate that cell (platelets and pancreatic acinar cells) stimulation with agonists induces a bimodal activation of caspase‐3. The early caspase‐3 activation occurs within 1 min of stimulation and is independent on caspase‐9 or mitochondrial cytochrome c release suggesting that is a non‐apoptotic event. The ability of agonists to induce early activation of caspase‐3 is similar to that observed for other physiological processes. Activation of caspase‐3 by physiological concentrations of cellular agonists, including thrombin or CCK‐8, is independent of rises in cytosolic calcium concentration but requires PKC activation, and is necessary for agonist‐induced activation of the tyrosine kinases Btk and pp60src and for several cellular functions, including store‐operated calcium entry, platelet aggregation, or pancreatic secretion. Thus, early activation of caspase‐3 seems to be a non‐apoptotic event required for cellular function. J. Cell. Physiol. 209: 142–152, 2006. © 2006 Wiley‐Liss, Inc.
Application of electrochemical oxidation for treatment of industrial wastewater — the influence of reactor hydrodynamics on direct and mediated processes
Authors: Szpyrkowicz Lidia 
Published: June 2006

AbstractThe influence of kinetic and hydrodynamic factors in electrochemical reactors used in the removal of pollutants from industrial wastewater is shown, distinguishing between the two main types of reactions, namely direct and mediated electro‐oxidation. The effect of stirring during treatment of four different types of wastewater is reported. Whilst for direct electro‐oxidation of pollutants, the influence of agitation on the performance of the reactor can be easily predicted from a mass transfer correlation, its effect during electro‐oxidation mediated in the homogeneous phase by a redox couple is not straightforward. The Hatta number can be a useful criterion to apply to electrochemical reactors performing mediated oxidation of compounds (in analogy to gas–liquid reactions), so as to define whether the reaction occurs in the bulk of the reactor or near the electrode, and thus can be affected differently by stirring. The hydrodynamic conditions in the reactor for treatment of industrial wastewater can affect the differential selectivity of the removal of pollutants and this can be used for optimising the performance of the reactor with respect to a target pollutant. Copyright © 2006 Society of Chemical Industry
Magnetic resonance imaging of experimental atherosclerotic plaque: Comparison of two ultrasmall superparamagnetic particles of iron oxide
Authors: Herborn Christoph U. , Vogt Florian M. , Lauenstein Thomas C. , Dirsch Olaf , Corot Claire , Robert Philippe , Ruehm Stefan G. 
Published: June 2006

AbstractPurposeTo evaluate a new ultrasmall superparamagnetic particles of iron oxide (USPIO) compound, ferumoxytol, as a marker of macrophage activity in atherosclerotic plaques and to compare it to ferumoxtran‐10.Materials and MethodsTen mature heritable hyperlipidemic (WHHL) female Watanabe rabbits served as the animal model for atherosclerosis, four coeval female New Zealand White (NZW) rabbits were the control group. Five WHHL and two NZW received a single intravenous injection (250 μmol/kg) of either ferumoxtran‐10 or ferumoxytol and were subjected to daily MR examinations on a 1.5T whole body scanner for the next five days. Development of signal intensity changes and susceptibility effects was assessed. Statistical analysis was based on a nonparametric Wilcoxon‐Mann‐Whitney‐U test by using a P value at the 0.05 significance level. On day 5, the rabbits were sacrificed and the aorta was referred to histopathology, distribution of iron particles in the vessel wall was analyzed.ResultsMRI was feasible in all animals. Three days after injection of ferumoxytol the highest luminal signal intensity measurements were observed in the ferumoxytol group; the highest measurements were five days after injection in the ferumoxtran‐10 group (P < 0.05). In the WHHL, susceptibility effects presented as homogeneous dark lines parallel to the aortic wall after ferumoxytol and spotted areas void of signal after ferumoxtran‐10. None of these findings were observed in the NZW control groups.ConclusionFerumoxtran‐10 and ferumoxytol at a respective dose of 250 μmol/kg appear well suited for atherosclerotic plaque detection with MRI in experimental atherosclerosis. Ferumoxytol warrants further analysis in humans. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Involvement of the nitric oxide/protein kinase G pathway in polychlorinated biphenyl‐induced cell death in SH‐SY 5Y neuroblastoma cells
Authors: Canzoniero Lorella M.T. , Adornetto Annagrazia , Secondo Agnese , Magi Simona , Dell'Aversano Carmela , Scorziello Antonella , Amoroso Salvatore , Di Renzo Gianfranco 
Published: June 2006

AbstractPolychlorinated biphenyls (PCB) are persistent environmental contaminants whose chronic exposure can affect nervous system development and function. The cellular and molecular mechanisms underlying neuronal damage are not yet clear. In the present study, we investigated whether nitric oxide (NO) could be involved in aroclor 1254 (A1254; a PCB mixture)‐induced cytotoxicity in SH‐SY5Y human neuroblastoma cells. Prolonged exposure (24 hr) to A1254 (10–100 μg/ml) caused a dose‐dependent reduction of cell viability that was attenuated in the presence of a calcium entry blocker, gadolinum (Gd3+) at 10 μM, a concentration able to block voltage‐sensitive calcium channels. In addition, A1254 caused an increase of cytosolic calcium that was dependent on extracellular calcium, as measured by fura‐2 videomicroscopy. A1254‐induced calcium rise may stimulate NO production through an activation of neuronal NOS (nNOS). Indeed, the concomitant addition of the selective nNOS inhibitor Nω‐propyl‐L‐arginine (NPLA) and A1254 prevented cell injury, suggesting that NO production plays a major role in A1254‐evoked cell injury. Furthermore, the exposure (14 hr) to A1254 (30 μg/ml) produced an up‐regulation of the expression of β isoform of nNOS. This up‐regulation was calcium dependent and was accompanied by an enhancement of NO production as demonstrated by an increase of nitrite formation. Moreover, A1254‐induced cell injury was prevented when KT 5823, a selective cGMP/PKG inhibitor, was added concomitantly to 30 μg/ml A1254. These results suggest that PCB‐induced cell death in neuroblastoma cells is mediated by an activation of the cGMP/PKG pathway triggered by NO production. © 2006 Wiley‐Liss, Inc.
New role for spinal Stargazin in α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid receptor‐mediated pain sensitization after inflammation
Authors: Tao Feng , Skinner John , Su Qingning , Johns Roger A. 
Published: June 2006

AbstractConsiderable evidence has demonstrated that α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) receptor blockade has an antinociceptive effect on inflammatory pain. Stargazin (STG) is the first transmembrane protein known to associate with AMPA receptors and regulate their synaptic targeting. However, it is not known whether STG is involved in inflammatory pain processing by regulating AMPA receptor function. In the present study, we investigated the effect of knockdown of spinal STG on AMPA receptor‐mediated pain sensitization after inflammation. Antisense technology was employed to knock down STG expression in the spinal cord. We show that STG was expressed and interacted with AMPA receptor subunit GluR2 in the spinal cord. Intrathecally injected STG antisense oligodeoxyribonucleotide (ODN) specifically decreased STG expression in the lumbar spinal cord and dose dependently inhibited formalin‐induced inflammatory pain in the second phase. More important was our finding for the first time that this specific STG antisense ODN diminished AMPA (0.1 μg)‐enhanced formalin pain and lost its effect if pretreated with AMPA receptor antagonist CNQX. Our results demonstrate a new role for STG in central sensitization of inflammatory pain by interacting with AMPA receptors in the spinal cord. © 2006 Wiley‐Liss, Inc.
Organizational identification versus organizational commitment: self‐definition, social exchange, and job attitudes
Authors: van Knippenberg Daan , Sleebos Ed 
Published: June 2006

AbstractThe psychological relationship between individual and organization has been conceptualized both in terms of identification and in terms of (affective) commitment. In the present study, we explore the differences between these two conceptualizations. Building on the proposition that identification is different from commitment in that identification reflects the self‐definitional aspect of organizational membership whereas commitment does not, we propose that commitment is more contingent on social exchange processes that presume that individual and organization are separate entities psychologically, and more closely aligned with (other) job attitudes. In support of these propositions, results of a cross‐sectional survey of university faculty (n=133) showed that identification is uniquely aligned (i.e., controlling for affective commitment) with the self‐referential aspect of organizational membership, whereas commitment is uniquely related (i.e., controlling for identification) to perceived organizational support, job satisfaction, and turnover intentions. We conclude that the core difference between identification and commitment lies in the implied relationship between individual and organization: Identification reflects psychological oneness, commitment reflects a relationship between separate psychological entities. Copyright © 2006 John Wiley & Sons, Ltd.
A matter of feeling? The affective tone of organizational commitment and identification
Authors: Herrbach Olivier 
Published: June 2006

AbstractThis paper examines the relationship between organizational commitment, organizational identification, and self‐reported affect at work. The results of a questionnaire survey of 365 engineers show that affective organizational commitment was correlated with experiencing more positive affective states. On the other hand, continuance commitment was not characterized as involving significant negative affect. Organizational identification was correlated with the frequency of both positive and negative affective states, but the correlation with positive affect was no longer significant when controlling for affective commitment. The paper concludes with comments on the nature of organizational commitment and identification, based on these findings. Copyright © 2006 John Wiley & Sons, Ltd.
The relationship between affective and normative commitment: review and research agenda
Authors: Bergman Mindy E. 
Published: June 2006

AbstractMeyer and Allen's (1991, 1997) three component conceptualization of organizational commitment (OC) includes affective (AC), continuance (CC), and normative (NC) commitment. However, AC and NC have not been as empirically differentiated as theoretically expected. Drawing on the extant literature, I review, integrate, and expand on arguments and evidence about the lack of AC‐NC differentiation. I also propose several avenues for research that could help commitment scholars attain a clearer picture of the true relationship between AC and NC, as the extant literature has inadequately addressed many issues regarding construct differentiation. Specific, testable propositions address a variety of facets of the commitment literature, including construct definition and measurement, developmental processes, relationships among the components and their unique and joint effects on outcomes, and potential moderators of the AC‐NC relationship. The goal of this paper is to spur future research into the AC‐NC relationship in order to gain greater construct clarity. Copyright © 2006 John Wiley & Sons, Ltd.
Preferential flow descriptions for structured soils
Authors: Gerke Horst H. 
Published: June 2006

AbstractIn heterogeneous structured soils, water and transported dissolved substances and suspended particles and colloids may under certain conditions bypass most of the soil porous matrix thereby creating nonequilibrium conditions in pressure heads and solute concentrations between preferential flow paths and the soil matrix pore region. Preferential flow severely limits the applicability of standard models for flow and transport that are mostly based on Richards' equation and the convection‐dispersion equation. A number of various model approaches have been proposed to overcome this problem. These models mostly try to separately describe flow and transport in preferred flow paths and slow or stagnant pore regions. Discrete fracture models are more frequently suggested in hydrogeology and often more empirically for cracked clay soils. The two‐domain approach assumes two interacting porous continua for either mobile‐immobile (compartment models) or mobile‐mobile pore systems for solute transport and for water movement. Such models were derived by rigorous “upscaling” methods (microstructure models), or by more empirically assuming two macroscopic scale systems. Representation of effective local (i.e., structural) geometry remains a problem when applying these models to soil systems. The dual‐permeability models differ in the description of flow in the preferential flow domain (i.e., either Richards' equation assuming capillarity or kinematic wave approach for gravity flow) and with respect to the mass‐transfer formulation (i.e., from pressure head– or saturation‐based first‐order type formulations to more complex nonlinear formulations or numerical solutions of the local flow equation). Despite the enormous progress that has been accomplished to improve both the modeling as well as the parameter determination, many challenges remain, in particular, how to capture dynamic soil structure effects to improve quantitative understanding and descriptions of preferential flow and transport processes.
Distribution and genesis of Fahlerden (Albeluvisols) in Germany
Authors: Kühn Peter , Billwitz Konrad , Bauriegel Albrecht , Kühn Dieter , Eckelmann Wolf 
Published: June 2006

AbstractFahlerden dominate large areas of the young and old moraine landscapes of N and E Germany. Fahlerden (part of Fahlerden corresponds to Albeluvisols) and their transitional subtypes are supposed to have a higher intensity of clay illuviation than Parabraunerden (Luvisols). Besides this macroscopic feature reflecting periglacial influence, micromorphological features such as lenticular platy microstructure, vesicles, and fragments of clay coatings in Bt streaks document the initiation of Fahlerde genesis, which began in the Late Glacial. A model of Fahlerde genesis chronologically connects sedimentological and periglacial processes, vegetation development, and soil‐forming processes like decalcification, clay illuviation, and humification. The classification criterion of larger differences in clay contents between E and Bt horizons to distinguish Fahlerden from Parabraunerden needs to be reconsidered, because most Fahlerden have developed in stratified parent material in periglacially influenced landscapes. The interpretation of a soil data base listing data of both soil types distributed in Brandenburg demonstrates that the difference in clay contents between E and Bt horizons may even be smaller in Fahlerden than in Parabraunerden.