bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterogene Katalyse. Schlüsseltechnologie der chemischen Industrie
Authors: Schüth Ferdi 
Published: April 2006

AbstractHeterogen katalysierte Reaktionen sind von enormer technischer Bedeutung. Zahlreiche Prozesse laufen an der Oberfläche fester Katalysatoren mit hoher Geschwindigkeit und Selektivität ab.Durch moderne Methoden haben wir mittlerweile detaillierte Einblicke in den Ablauf vieler katalytischer Reaktionen gewonnen, teilweise können die Ergebnisse von Experimenten unter Ultrahochvakuumbedingungen auf die Bedingungen des technischen Prozesses extrapoliert werden. Wesentliche Reaktionsklassen werden diskutiert und an vier technischen Beispielen unterschiedliche Aspekte heterogen katalysierter Reaktionen erläutert.
Asymmetrische Katalyse mit Metall‐Komplexen. Bild oder Spiegelbild?
Authors: Muñiz Kilian 
Published: April 2006

AbstractDie asymmetrische Katalyse ist eine Schlüsseltechnologie. Der vorliegende Aufsatz diskutiert allgemeine Grundlagen und Prinzipien der asymmetrischen Katalyse und verdeutlicht die Funktionsweise anhand ausgewählter Beispielreaktionen. Diese beinhalten asymmetrische katalytische Hydrierungen von Alkenen, Ketonen und Iminen, asymmetrische Oxidationskatalysen wie die Dihydroxylierung und Epoxidierung von Alkenen sowie eine Reihe von asymmetrischen katalysierten C‐C‐Bindungsknüpfungen wie der allylischen Substitution, Cyclopropanierungen und Diels‐Alder‐Reaktionen sowie Dialkyl‐ und Diphenylzink‐Additionen an Aldehyde. Im jeweiligen Zusammenhang werden auch typische Katalysephänomene wie kinetische und dynamische kinetische Racematspaltung, Ligandenbeschleunigung, nicht‐lineare Effekte und asymmetrische Autokatalyse besprochen.
Chemie und Biologie Hand in Hand. Enzyme als Katalysatoren
Authors: Breuer Michael , Stürmer Rainer 
Published: April 2006

AbstractDie Biokatalyse hat sich in den letzten Jahren zu einer wichtigen Methode zur Herstellung von Feinchemikalien, Vitaminen, chiralen Zwischenprodukten und anderen Schlüsselprodukten der chemischen Industrie entwickelt. In Zukunft werden weitere Synthesen von Industriechemikalien auf der Basis nachwachsender Rohstoffe entwickelt werden. Man geht zudem davon aus, dass die Biokatalyse in Zukunft maßgeblich zur Herstellung von Biokraftstoffen sowie nachhaltigen und bioabbaubaren Polymeren beitragen wird.
Brennstoffzellen ohne Platin
Authors: Jaenicke Lothar 
Published: April 2006

AbstractIn Brennstoffzellen werden Protonen und Elektronen zu molekularem Wasserstoff vereinigt. Um die Aktivierungshürde zu überwinden, benötigt man einen beschleunigenden Katalysator. Die Technik verwendet dazu als Anode die kostbaren Übergangsmetalle aus der Platinreihe. Das ist jedoch keine brauchbare Lösung des im Wortsinn brennenden Ingenieursproblems. Platin ist nicht nur selten, daher teuer; sondern zudem nicht zu verantworten. Der unvermeidliche Abrieb belastet in unbekannter Weise die Umwelt.
Chirale Katalyse und Analyse auf einem Chip vereint
Authors: Groß Michael 
Published: April 2006

AbstractMiniaturisierung macht nicht nur Computer schneller, sondern auch chemische Reaktionen und Analysen im Mikroformat. Da aber der Gesamtprozess nur so schnell abgewickelt werden kann wie sein langsamster Schritt, sollten am besten alle Schritte von der Synthese bis zur Analyse auf einem Chip untergebracht werden.
Mesoblastic nephroma—A report from the Gesellschaft fur Pädiatrische Onkologie und Hämatologie (GPOH)
Authors: Furtwaengler Rhoikos , Reinhard Harald , Leuschner Ivo , Schenk Jens P. , Goebel Ulrich , Claviez Alexander , Kulozik Andreas , Zoubek Andreas , von Schweinitz Dietrich , Graf Norbert ,   Gesellschaft fur Pädiatrische Onkologie und Hämatologie (GPOH) Nephroblastoma Study Group
Published: April 2006

AbstractBACKGROUNDSurgery alone is the appropriate first‐line treatment for patients with mesoblastic nephroma (MN). Nevertheless, there are reports of local recurrences and metastasis, especially in the cellular subtype. The authors evaluated the outcome of patients with MN who were enrolled in either the International Society of Pediatric Oncology (SIOP) 93‐01/GPOH or the SIOP 2001/GPOH Nephroblastoma Study and Trial.METHODSIn total, 50 patients with MN were analyzed. Eleven patients were suspected antenatally of having a renal tumor. The median age at diagnosis was 18.5 days. Central pathologic review was performed for all specimens. The median observation time was 4.2 years.RESULTSForty‐five patients underwent initial surgery. Five patients older than 6 months received preoperative chemotherapy. Twenty‐nine tumors were classic MN, and 21 tumors were cellular MN. Nine patients had a Stage III MN, 5 of those patients had tumor ruptures, and 8 had positive surgical margins. After they underwent nephrectomy, 40 patients received no further treatment. For the entire group, event‐free survival (EFS) (94%) and overall survival (OS) (95%) were excellent. Patients with a cellular MN, patients with age 3 months or older, and patients with Stage III MN had lower EFS. Three patients developed recurrent disease, and 2 of those patients died. Metastases to the brain, lung, and liver were observed in 1 patient.CONCLUSIONSRadical nephrectomy with accurate surgical‐pathologic staging is the standard of care for children with MN. Nonetheless, a subgroup of patients with MN (Stage III cellular MN in patients age 3 months or older) tends to develop recurrences more often. Further prospective studies will be needed to verify this finding and should help determine whether these patients may benefit from adjuvant therapy. Cancer 2006. © 2006 American Cancer Society.
Evaluation of the HER2/neu‐derived peptide GP2 for use in a peptide‐based breast cancer vaccine trial
Authors: Mittendorf Elizabeth A. , Storrer Catherine E. , Foley Rebecca J. , Harris Katie , Jama Yusuf , Shriver Craig D. , Ponniah Sathibalan , Peoples George E. 
Published: April 2006

AbstractBACKGROUNDE75 and GP2 are human leukocyte antigen (HLA)‐A2‐restricted immunogenic peptides derived from the HER2/neu protein. In a E75 peptide‐based vaccine trial, preexisting immunity and epitope spreading to GP2 was detected. The purpose of this study was to further investigate GP2 for potential use in vaccination strategies. Importantly, a naturally occurring polymorphism (I → V at position 2, 2VGP2) associated with increased breast cancer risk was addressed.METHODSPrevaccination peripheral blood samples (PBMC) from HLA‐A2 breast cancer patients and CD8+ T cells from HLA‐A2 healthy donors were stimulated with autologous dendritic cells (DC) pulsed with GP2 and tested in standard cytotoxicity assays with HER2/neu+ tumor cells or GP2‐ or 2VGP2‐loaded T2 targets. Additional cytotoxicity experiments used effectors stimulated with DC pulsed with E75, GP2, or the combination of E75+GP2.RESULTSGP2‐stimulated prevaccination PBMC from 28 patients demonstrated killing of MCF‐7, SKOV3‐A2, and the HLA‐A2− control target SKOV3 of 28.8 ± 3.7% (P<.01), 29.5 ± 4.0% (P<.01), and 16.9 ± 2.7%, respectively. When compared with E75, GP2‐stimulated CD8+ T cells lysed HER2/neu+ targets at 43.8 ± 5.2% versus 44.2 ± 5.7% for E75 (P = .87). When combined, an additive effect was noted with 58.6 ± 5.4% lysis (P = .05). GP2‐stimulated CD8+ T cells specifically recognized both GP2‐loaded (19.6 ± 5.7%) and 2VGP2‐loaded T2 targets (17.7 ± 5.2%).CONCLUSIONSGP2 is a clinically relevant HER2/neu‐derived peptide with immunogenicity comparable to that of E75. Importantly, GP2‐specific effectors recognize 2VGP2‐expressing targets; therefore, a GP2 vaccine should be effective in patients carrying this polymorphism. GP2 may be most beneficial used in a multiepitope vaccine. Cancer 2006. Published 2006 by the American Cancer Society.
Phase II study of capecitabine combined with gemcitabine in the treatment of androgen‐independent prostate cancer previously treated with taxanes
Authors: Rodney Alan , Dieringer Pauline , Mathew Paul , Jonasch Eric , Tannir Nizar , Pagliaro Lance C. 
Published: April 2006

AbstractBACKGROUNDThe primary objective of the current study was to evaluate the effectiveness of capecitabine and gemcitabine in the treatment of patients with androgen‐independent prostate cancer (AIPCa) who experienced disease progression after taxane therapy. The secondary objective was to evaluate the safety and tolerability of the combination of capecitabine and gemcitabine in these patients.METHODSPatients with AIPCa, either metastatic or unresectable disease, and prior taxane therapy were eligible. Patients were treated with 800 mg/m2 of capecitabine orally twice daily (1600 mg/m2 per day) for 14 days, and 800 mg/m2 of gemcitabine intravenously on Days 1 and 8. This regimen was repeated every 21 days. Response to therapy was determined by measuring prostate‐specific antigen concentration.RESULTSSixteen patients participated in this study from June 2003 to January 2004. There were no responses as defined by a 50% decline in prostate‐specific antigen. The study was terminated early because the response rate was not projected to exceed 30% (rejection error of 10%). Toxicities were notable: 3 patients had Grade 3 thrombocytopenia, 4 patients had Grade 3 neutropenia, and 3 patients had Grade 3 infections (according to the National Cancer Institute Common Toxicity Criteria [version 2.0]). Eight patients (50%) required dose reduction or treatment interruption.CONCLUSIONSThe combination of capecitabine and gemcitabine for the salvage treatment of patients with AIPCa was associated with significant toxicities and was ineffective for induction of disease regression. Cancer 2006. © 2006 American Cancer Society.
Highly Anisotropic Orbitally Dependent Superexchange in Cyano‐Bridged Clusters Containing Mn(III) and Mn(II) Ions
Authors: Palii Andrew , Ostrovsky Sergey M. , Klokishner Sophia I. , Tsukerblat Boris. S. , Dunbar Kim R. 
Published: April 2006

AbstractWe study the orbitally dependent magnetic exchange in cyanide‐based clusters as a source of the barrier for reversal magnetization. We consider the Mn(III)–CN–Mn(II) dimer and linear Mn(II)–NC–Mn(III)–CN–Mn(II) trimer containing octahedrally coordinated Mn(III) and Mn(II) ions with special emphasis on the magnetic manifestations of the orbital degeneracy of the Mn(III) ion. The kinetic exchange mechanism involves the electron transfer from the single occupied t2 orbitals of the Mn(II) ion [${{}^6A_{\,1} \left( {t_2^3 e^2 } \right)}$ ground state] to the singly occupied t2 orbitals of the Mn(III) ion [${{}^3T_{\,1} \left( {t_2^4 } \right)}$ ground state] resulting in the charge‐transfer ${{}^5T_2 \left( {t_2^2 e^2 } \right)_{Mn(III)} }$${ - {}^2T_2 \left( {t_2^5 } \right)_{Mn(II)} }$ state of the pair. The deduced effective exchange Hamiltonian that takes into account orbital degeneracy leads to an essentially non‐Heisenberg energy pattern. The energy levels are shown to be dependent on both spin and orbital quantum numbers, thus providing direct information about the magnetic anisotropy of the system. Along with the magnetic exchange, the model includes an axial component of the crystal field and spin–orbit coupling operating within the ground ${{}^3T_1 \left( {t_2^4 } \right)}$ cubic term of the Mn(III) ion. We have shown that under certain conditions both named interactions lead to the occurrence of the barrier for the reversal of magnetization, which significantly increases when passing from the dimer to the trimer. This provides a possible way for raising the magnetic barrier in the family of cyano‐bridged manganese clusters.
Kinetic Model of Energy Transfer Processes Between Low‐Coordinated Ions on MgO by Photoluminescence Decay Measurements
Authors: Chizallet Céline , Costentin Guylène , Krafft Jean‐Marc , Lauron‐Pernot Hélène , Che Michel 
Published: April 2006

AbstractPhotoluminescence decay studies of emitting species on MgO nanocubes at room temperature provide evidence of three surface species characterized by an excitation and emission wavelength couple {λexc;λem}. Species A corresponds to {λexc=240 nm; λem=380 nm}, whereas the couple {λexc=280 nm; λem=470 nm} is assigned to two species: B and B′, the former is involved in energy transfer from excited state A* and the latter in direct emission from excited state B′*. A simple model for energy transfer from species A* to B is proposed. The numerical resolution of equations corresponding to this model is in good agreement with experimental data. This method quantifies the kinetics of intrinsic emission and energy transfer processes. Lifetime values indicate that phosphorescence is taking place, and species A, B and B′ are identified as edge O2−4 C, corner O2−3 C and kink O2−3 C oxide ions respectively.
Conformational Effects on Circular Dichroism in the Photoelectron Angular Distribution
Authors: Di Tommaso Devis , Stener Mauro , Fronzoni Giovanna , Decleva Piero 
Published: April 2006

AbstractThe B‐spline density‐functional method has been applied to the conformers of the (1R, 2R)‐1,2‐dibromo‐1,2‐dichloro‐1,2‐difluoroethane molecule. The cross section, asymmetry, and dichroic parameters relative to core and valence orbitals, which do not change their nature along the conformational curve, have been systematically studied. While the cross section and the asymmetry parameter are weakly affected, the dichroic parameter appears to be rather sensitive to the particular conformer of the molecule, suggesting that this dynamical property could be a useful tool for conformational analysis. The computational method has also been applied to methyl rotation in methyloxirane. Unexpected and dramatic sensitivity of the dichroic‐parameter profile to the methyl rotation, both in the core and valence states, has been found. Boltzmann averaging over the conformers reproduces quite closely the profiles previously obtained for the minimum‐energy conformation, which is in good agreement with the experimental results.
Spin–Orbit Ab Initio Investigation of the Photolysis of Bromoiodomethane
Authors: Liu Ya‐Jun , Ajitha Devarajan , Krogh Jesper Wisborg , Tarnovsky Alexander N. , Lindh Roland 
Published: April 2006

AbstractThe photodissociation of bromoiodomethane has been investigated by spin–orbit ab initio calculations. The experimentally observed A‐ and B‐bands and the corresponding photoproducts were assigned by multistate second‐order multiconfigurational perturbation theory in conjunction with spin–orbit interaction through complete active space state interaction potential energy curves, vertical excitation energies, and oscillator strengths of low‐lying excited states. The present conclusions with respect to the dissociation process in the B‐band are different compared with those of previous studies. The reaction between the iso‐CH2Br‐I and iso‐CH2I‐Br species has also been studied. Finally, a set of stable excited states was identified for both isomers. These species might be of importance in the recombination process that follows the photodissociation in a solvent.
Functional CD1a is stabilized by exogenous lipids
Authors: Manolova Vania , Kistowska Magdalena , Paoletti Samantha , Baltariu Gabriel M. , Bausinger Huguette , Hanau Daniel , Mori Lucia , De Libero Gennaro 
Published: April 2006

AbstractSelf‐glycosphingolipids bind to surface CD1 molecules and are readily displaced by other CD1 ligands. This capacity to exchange antigens at the cell surface is not common to other antigen‐presenting molecules and its physiological importance is unclear. Here we show that a large pool of cell‐surface CD1a, but not CD1b molecules, is stabilized by exogenous lipids present in serum. Under serum deprivation CD1a molecules are altered and functionally inactive, as they are unable to present lipid antigens to T cells. Glycosphingolipids and phospholipids bind to, and restore functionality to CD1a without the contribution of newly synthesized and recycling CD1a molecules. The dependence of CD1a stability on exogenous lipids is not related to its intracellular traffic and rather to its antigen‐binding pockets. These results indicate a functional dichotomy between CD1a and CD1b molecules and provide new information on how the lipid antigenic repertoire is immunologically sampled.
Oxidorhenium(V) Complexes of a Family of Bipyridine‐Like Ligands Including Pyridyltriazines and Pyrazinyltriazine: Oxygen‐Atom Transfer, Metal Redox and Correlations
Authors: Das Samir , Chakravorty Animesh 
Published: April 2006

AbstractThe title ligands (general abbreviation L) are bipyridine (bpy), its dimethyl (mbpy) and diphenyl (pbpy) derivatives, phenanthroline (phen), 5,6‐diphenyl‐3‐(2‐pyridyl)‐1,2,4‐triazine (ppyt) and its dimethyl (mpyt) and pyrazinyl (ppzt) analogues. The concerned oxido complexes are [ReOCl3(L)],[ReOBr3(ppyt)] and [ReOBr3(ppzt)]. The chloro and bromo complexes of ppyt and ppzt were prepared by reacting these ligands with [ReOX3(AsPh3)2] (X = Cl, Br). The X‐ray structures of [ReOCl3(ppyt)] and [ReOCl3(ppzt)] reveal that the ReCl3fragment is meridionally disposed and that the L ligand isN,N‐coordinated such that the pyridine/pyrazine nitrogen liestransto the oxido oxygen atom. The Re–O lengths [1.656(10)/1.625(9) Å] correspond to approximate triple bonding. The rate of oxygen‐atom transfer from [ReOX3(L)] to triphenylphosphane in solution follows second‐order kinetics and is associated with a large and negative entropy of activation (approx. –30 cal K–1 mol–1). The initial attack is believed to involve the phosphane lone pair and Re≡O π*‐orbitals. Electron withdrawal from the ReVO moiety by varying X or L facilitates oxygen‐atom transfer. Thus, the rates follow the orders Br < Cl; mbpy < bpy < phen < pbpy << mpyt < ppyt < ppzt. The reduction potential of the quasireversible ReVIO/ReVO couple displays similar trends and the logarithmic rate constant of oxygen‐atom transfer is found to correlate linearly with the reduction potential. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Runoff and soil loss under individual plants of a semi‐arid Mediterranean shrubland: influence of plant morphology and rainfall intensity
Authors: Bochet E. , Poesen J. , Rubio J. L. 
Published: April 2006

AbstractThe influence of plant morphology and rainfall intensity on soil loss and runoff was determined at the plant scale for three representative species of a semi‐arid patchy shrubland vegetation of east Spain, representing contrasting canopy structures and plant phenologies (Rosmarinus officinalis, Anthyllis cytisoides and Stipa tenacissima).Twenty‐seven microplots of less than 1 m2, each containing one single plant, were built to quantify runoff volume and sediment yield under the canopies of the three species. Runoff and rates of soil loss measured in these plots under natural rainfall conditions were compared with control microplots built in the bare inter‐plant areas. Precipitation was automatic‐ally recorded and rainfall intensity calculated over a two‐year period.Results indicated that individual plants played a relevant role in interrill erosion control at the microscale. Compared with a bare soil surface, rates of soil loss and runoff reduction varied strongly depending on the species. Cumulative soil loss was reduced by 94·3, 88·0 and 30·2 per cent, and cumulative runoff volume was reduced by 66·4, 50·8 and 18·4 per cent under the Rosmarinus, Stipa and Anthyllis canopies, respectively, compared with a bare surface. Anthyllis was significantly less efficient than the two other species in reducing runoff volume under its canopy. Differences between species could only be identified above a rainfall intensity threshold of 20 mm h−1. The different plant morphologies and plant compon‐ents explained the different erosive responses of the three species. Canopy cover played a major role in runoff and soil loss reduction. The presence of a second layer of protection at the soil surface (litter cover) was fundamental for erosion control during intense rainfall. Rainfall intensity and soil water status prior to rainfall strongly influenced runoff and soil loss rates. The possible use of these species in restoration programmes of degraded areas is discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Analysis of functional image analysis contest (FIAC) data with brainvoyager QX: From single‐subject to cortically aligned group general linear model analysis and self‐organizing group independent component analysis
Authors: Goebel Rainer , Esposito Fabrizio , Formisano Elia 
Published: April 2006

AbstractThe Functional Image Analysis Contest (FIAC) 2005 dataset was analyzed using BrainVoyager QX. First, we performed a standard analysis of the functional and anatomical data that includes preprocessing, spatial normalization into Talairach space, hypothesis‐driven statistics (one‐ and two‐factorial, single‐subject and group‐level random effects, General Linear Model [GLM]) of the block‐ and event‐related paradigms. Strong sentence and weak speaker group‐level effects were detected in temporal and frontal regions. Following this standard analysis, we performed single‐subject and group‐level (Talairach‐based) Independent Component Analysis (ICA) that highlights the presence of functionally connected clusters in temporal and frontal regions for sentence processing, besides revealing other networks related to auditory stimulation or to the default state of the brain. Finally, we applied a high‐resolution cortical alignment method to improve the spatial correspondence across brains and re‐run the random effects group GLM as well as the group‐level ICA in this space. Using spatially and temporally unsmoothed data, this cortex‐based analysis revealed comparable results but with a set of spatially more confined group clusters and more differential group region of interest time courses. Hum. Brain Mapp, 2006. © 2006 Wiley‐Liss, Inc.
Combined permutation test and mixed‐effect model for group average analysis in fMRI
Authors: Mériaux Sébastien , Roche Alexis , Dehaene‐Lambertz Ghislaine , Thirion Bertrand , Poline Jean‐Baptiste 
Published: April 2006

AbstractIn group average analyses, we generalize the classical one‐samplettest to account for heterogeneous within‐subject uncertainties associated with the estimated effects. Our test statistic is defined as the maximum likelihood ratio corresponding to a Gaussian mixed‐effect model. The test's significance level is calibrated using the same sign permutation framework as in Holmes et al., allowing for exact specificity control under a mild symmetry assumption about the subjects' distribution. Because our likelihood ratio test does not rely on homoscedasticity, it is potentially more sensitive than both the standardttest and its permutation‐based version. We present results from the Functional Imaging Analysis Contest 2005 dataset to support this claim. Hum Brain Mapp 27:402–410, 2006. © 2006 Wiley‐Liss, Inc.