bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Nonequilibrium, Atmospheric‐Pressure Argon Plasma Torch for Deposition of Thin Silicon Dioxide Films
Authors: Kasih T. P. , Kuroda S. , Kubota H. 
Published: April 2007

AbstractA nonequilibrium, atmospheric‐pressure plasma torch that can be generated either in He or Ar gas by using a pulsed high‐voltage power supply with the discharge temperature in the range 22–35 °C has been developed. This system is used to deposit silicon dioxide films from a hexamethyldisiloxane (HMDSO) precursor diluted in an oxygen carrier gas. It is concluded that, in terms of both quality and deposition rate at the same applied power, frequency, and gas composition, Ar plasma is more powerful than He plasma for depositing SiO2‐like films. The maximum feed rate of HMDSO/O2 injected into the Ar plasma torch is limited to 100 mL min–1 to ensure inorganic coatings are deposited. In order to improve the visual quality, without adversely affecting the inorganic features of the film, a small amount of nitrogen (N2) can be added to the Ar as a working gas. When the ratio of Ar to N2 in the flow gas is 30:1, the discharge behavior is transformed from filamentary to glowlike as a result of the quenching effect of admixed N2 on Ar plasma.
Synthesis and Functional Properties of Vanadium Oxides: V2O3, VO2, and V2O5 Deposited on Glass by Aerosol‐Assisted CVD
Authors: Piccirillo C. , Binions R. , Parkin I. P. 
Published: April 2007

AbstractThin films of vanadium oxides were deposited on glass by aerosol‐assisted (AA) CVD from vanadium(III) acetylacetonate and vanadyl(IV) acetylacetonate. The vanadium precursor, solvent, and carrier gas flow rate determined the phase of vanadium oxide formed (V2O3, VO2, or V2O5). Films were characterized using various analytical techniques. VO2 films were analyzed at various temperatures to study their thermochromic behavior. The V2O3 reflectance‐transmission plots showed a cross‐over (ideal behavior for a solar‐control mirror).
CVD of MgO Thin Films from Bis(methylcyclopentadienyl) Magnesium
Authors: Carta G. , El Habra N. , Crociani L. , Rossetto G. , Zanella P. , Zanella A. , Paolucci G. , Barreca D. , Tondello E. 
Published: April 2007

AbstractThin films of MgO are grown by CVD, with a high growth rate, on Si(001) and quartz substrates in the temperature range 400–550 °C, using bis(methylcyclopentadienyl)magnesium [Mg(CH3‐C5H4)2] as the precursor. The films obtained are investigated by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and optical absorption, in order to investigate the interrelations between film properties and processing conditions. Cubic phase MgO (periclase) films, characterized by a low carbon contamination and a granular surface morphology, are obtained.
Abnormal lens morphogenesis and ectopic lens formation in the absence of β‐catenin function
Authors: Kreslova Jana , Machon Ondrej , Ruzickova Jana , Lachova Jitka , Wawrousek Eric F. , Kemler Rolf , Krauss Stefan , Piatigorsky Joram , Kozmik Zbynek 
Published: April 2007

Abstractβ‐Catenin plays a key role in cadherin‐mediated cell adhesion as well as in canonical Wnt signaling. To study the role of β‐catenin during eye development, we used conditional Cre/loxP system in mouse to inactivate β‐catenin in developing lens and retina. Inactivation of β‐catenin does not suppress lens fate, but instead results in abnormal morphogenesis of the lens. Using BAT‐gal reporter mice, we show that β‐catenin‐mediated Wnt signaling is notably absent from lens and neuroretina throughout eye development. The observed defect is therefore likely due to the cytoskeletal role of β‐catenin, and is accompanied by impaired epithelial cell adhesion. In contrast, inactivation of β‐catenin in the nasal ectoderm, an area with active Wnt signaling, results in formation of crystallin‐positive ectopic lentoid bodies. These data suggest that, outside of the normal lens, β‐catenin functions as a coactivator of canonical Wnt signaling to suppress lens fate. genesis 45:157–168, 2007. Published 2007 Wiley‐Liss, Inc.
Virus recognition by specific natural antibodies and complement results in MHC I cross‐presentation
Authors: Dürrbach Antoine , Baple Emma , Preece Andrew F. , Charpentier Bernard , Gustafsson Kenth 
Published: April 2007

AbstractNatural antibodies (NAb) and complement (C’) are important regulators of immune system activation. We have shown previously that the galactosyl‐α1,3‐galactosyl (Galα1,3Gal) xenoantigen and the similar ABO histo‐blood group antigens are transferred onto virus from the producer cell, resulting in sensitisation of the virus to the respective NAb in a C’‐dependent manner. Here we show that measles virus (Mv) that expresses Galα1,3Gal termini can drive the proliferation of human T cells in the presence of serum and autologous DC, whereas without such targets, measles, as expected, suppress T cell reactivity. The use of affinity‐purified NAb to Galα1,3Gal and rabbit C’ demonstrated the components in human serum responsible for this effect. Proteasome inhibition and blocking of antigen presentation showed that the increased T cell proliferation was mediated by MHC class I cross‐presentation of immune complexes. These results lend further support to the idea that polymorphic carbohydrates of the Galα1,3Gal/ABO type serve as important targets for NAb and C’ and that their expression on virus has influenced their evolution by contributing to protection against viral transmission within as well as between species. The adjuvance effect of this recognition, acting as a bridge between the natural innate and adaptive immune systems, also has important implications for vaccine development.
NF‐κB‐regulated suppression of T‐bet in T cells represses Th1 immune responses in pregnancy
Authors: McCracken Sharon A. , Hadfield Katrina , Rahimi Zolaikha , Gallery Eileen D. , Morris Jonathan M. 
Published: April 2007

AbstractThe molecular mechanisms that suppress Th1 immune responses in pregnancy are unknown. We assessed the expression of the Th1 cytokine transcription factor T‐bet. We isolated PBMC and T cells from non‐pregnant and pregnant women and demonstrated that T‐bet is specifically down‐regulated in pregnancy under basal and stimulated conditions. Low levels of T‐bet protein were detected in the nuclear fraction of unstimulated PBMC from non‐pregnant, but not pregnant women. Nuclear levels of T‐bet increased in response to PMA/ionomycin in PBMC from non‐pregnant, but not pregnant women. T‐bet expression was greater in whole cell lysates of stimulated CD3+ T cells from non‐pregnant relative to pregnant women. NF‐κB is specifically down‐regulated in T cells in pregnant women, resulting in suppressed expression of Th1 cytokines IL‐2, IFN‐γ and TNF‐α. In this study, down‐regulation of NF‐κB also resulted in diminished expression of T‐bet. PMA induces NF‐κB translocation, T‐bet expression and IL‐2, IFN‐γ and TNF‐α production. Conversely, pre‐incubation with SN50, and NF‐κB oligodeoxyribonucleotide decoys suppressed PMA‐induced NF‐κB translocation and gene transcription, respectively, resulting in diminished T‐bet expression and Th1 cytokine production. Therefore, maintenance of the cytokine environment for pregnancy success is mediated via strict regulation of Th1 immune responses, more specifically through control of NF‐κB and T‐bet transcription.
PPARγ‐dependent regulation of human macrophages in phagocytosis of apoptotic cells
Authors: Majai Gyöngyike , Sarang Zsolt , Csomós Krisztián , Zahuczky Gábor , Fésüs László 
Published: April 2007

AbstractMacrophages acquire their capacity for efficient phagocytosis of apoptotic cells during their differentiation from monocytes. The peroxisome proliferator‐activated receptor gamma (PPARγ) is highly up‐regulated during this maturation program. We report that addition of PPARγ antagonist during differentiation of human monocytes to macrophages significantly reduced the capacity of macrophages to engulf apoptotic neutrophils, but did not influence phagocytosis of opsonized bacteria. Macrophage‐specific deletion of PPARγ in mice also resulted in decreased uptake of apoptotic cells. The antagonist acted in a dose‐dependent manner during the differentiation of human macrophages and could also reverse the previously observed augmentation of phagocytosis by glucocorticoids. Blocking activation of PPARγ led to down‐regulation of molecular elements (CD36, AXL, TG2 and PTX3) of the engulfment process. Inhibition of PPARγ‐dependent gene expression did not block the anti‐inflammatory effect of apoptotic neutrophils or synthetic glucocorticoid, but significantly decreased production of IL‐10 induced by LPS. Our results suggest that during differentiation of macrophages natural ligands of PPARγ are formed, regulating the expression of genes responsible for effective clearance of apoptotic cells and macrophage‐mediated inflammatory responses.
CD4‐mediated functional activation of human CD4+CD25+ regulatory T cells
Authors: Becker Christian , Kubach Jan , Wijdenes John , Knop Jürgen , Jonuleit Helmut 
Published: April 2007

AbstractNaturally occurring CD4+CD25+FoxP3+ regulatory T cells (CD25+ Tregs) constitute a specialized population of T cells that is essential for the maintenance of peripheral self‐tolerance. The immune regulatory function of CD25+ Tregs depends upon their activation. We found that anti‐CD4 antibodies activate the suppressive function of human CD25+ Tregs in a dose‐dependent manner. We demonstrate that CD4‐activated CD25+ Tregs suppress the proliferation of CD4+ and CD8+ T cells, their IL‐2 and IFN‐γ production as well as the capacity of CD8+ T cells to re‐express CD25. By contrast, anti‐CD4 stimulation did not induce suppressive activity in conventional CD4+ T cells. These results identify CD4 as a trigger for the suppressive function of CD25+ Tregs and suggest a possible CD4‐mediated exploitation of these cells.
Broadening the Scope of Ancillary Phosphane‐Type Ligands: A Systematic Comparison of PR3, PR2BH3–, and SiR3– and Their Chalcogen Derivatives
Authors: Kückmann Theresa I. , Dornhaus Franz , Bolte Michael , Lerner Hans‐Wolfram , Holthausen Max C. , Wagner Matthias 
Published: April 2007

AbstractThis work describes a systematic experimental and theoretical study of the properties of two series of isoelectronic and largely isosteric ligands, namely PPh2Me, PPh2BH3–, and SiPh2Me– and SPtBu3, SPtBu2BH3–, and SSitBu3–. In addition, we have also investigated the oxo derivatives OPPh2BH3– and OSiPh2Me–. Based on X‐ray crystal structure determinations (Fe–CO and C–O bond lengths) as well as NMR [e.g. δ(13CO)] and IR [ν(CO)] spectroscopic investigations of the corresponding [CpFe(CO)2]+ complexes, we can conclude that, with respect to electron donor strength, phosphanyl borohydrides occupy an intermediate position between phosphanes (weakest donors) and silyl ligands (strongest donors). The same is true for the thio derivatives, although the differences are smaller. In the reaction with [CpFe(CO)2]+, the oxo derivative OPPh2BH3– transfers a hydride ion rather than forming a stable [CpFe(CO)2(OPPh2BH3)] complex. The tendency to undergo hydride‐transfer reactions was studied by density functional calculations for the series PtBu2BH3–, OPtBu2BH3–, and SPtBu2BH3–. The results reveal that OPtBu2BH3– is the strongest and SPtBu2BH3– the weakest hydride donor, in accordance with the experimental observations. Theoretical analysis indicates that the three derivatives PPh2Me, PPh2BH3–, and SiPh2Me– are truly isolobal species despite variations in their charge distributions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Metal Ion Complementarity: Effect of Ring‐Size Variation on the Conformation and Stability of Lead(II) and Cadmium(II) Complexes with Pendant‐Armed Crowns
Authors: Regueiro‐Figueroa Martín , Esteban‐Gómez David , Platas‐Iglesias Carlos , de Blas Andrés , Rodríguez‐Blas Teresa 
Published: April 2007

AbstractThe binding tendencies of the pendant‐armed crown ethers L1–L3 [L1 = N,N′‐bis(benzimidazol‐2‐ylmethyl)‐1,7‐diaza‐12‐crown‐4, L2 = N,N′‐bis(benzimidazol‐2‐ylmethyl)‐1,10‐diaza‐15‐crown‐5) and L3 = N,N′‐bis(benzimidazol‐2‐ylmethyl)‐4,13‐diaza‐18‐crown‐6] towards PbII and CdII have been investigated. The X‐ray crystal structure of [Cd(L3)](ClO4)2·EtOH shows that, in the solid state, the CdII ion is eight‐coordinate and fits quite well into the crown hole, favouring an anti arrangement of the organic receptor. NMR measurements recorded in acetonitrile solution indicate that increasing the crown size induces a conformational change in the series of CdII complexes. The conformation goes from a syn arrangement for L1 to an anti arrangement for L3, passing through a syn [lrarr2] anti equilibrium in the complex derived from L2. On the contrary, no conformational change was observed for the corresponding PbII complexes, which have a syn conformation in all cases. These results have been confirmed by means of density functional theory (DFT) calculations performed by using the B3LYP model. The binding constants obtained from UV/Vis titration experiments in DMSO solution demonstrate that a decrease in the crown size provokes a 102‐fold enhancement of the stability for this series of CdII complexes, whereas for PbII a gradual decrease of the binding constants is observed. Receptor L1 shows a certain degree of selectivity for CdII over PbII, with a selectivity factor > 102. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Hydrolysis of a (2‐Propanol)yttrium Triiodide Complex in the Presence of Glymes: Synthesis and X‐ray Structures of Hydroxo‐Bridged Dinuclear Yttrium Complexes and Their Applications in Materials Science
Authors: Mishra Shashank , Daniele Stéphane , Hubert‐Pfalzgraf Liliane G. , Jeanneau Erwann 
Published: April 2007

AbstractThe reactions of (2‐propanol)yttrium triiodide, Y(iPrOH)4I3, with stoichiometric amounts of water in the presence of di‐, tri‐, and tetraglyme yield a facile synthetic route to hydroxo‐bridged, centrosymmetric dimeric yttrium complexes. These ionic derivatives, [Y2L2(μ‐OH)2(H2O)x(ROH)y]I4 [1: L = triglyme, x = 2, y = 2, R = iPr; 2: L = tetraglyme, x = 2, y = 0; 3·2EtOH: L = diglyme, x = 2, y = 4, R = Et; 4·2EtOH: L = triglyme, x = 4, y = 0; 5: L = tetraglyme, x = 2, y = 2, R = Et] have been characterized by elemental analysis, IR and 1H NMR spectroscopy, as well as by single‐crystal X‐ray diffraction for 3, 4, and 5. Preliminary results on the utility of these ionic derivatives as potential sources of yttrium oxide in high Tc superconductors are also presented.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Bis‐μ‐pyrazolate‐Bridged Dinickel(II) and Dicopper(II) Complexes: An Example of Stereoelectronic Preference of Metal Ions and Stabilization of Mixed‐Valence NiIIINiII Species
Authors: Mishra Vibha , Lloret Francesc , Mukherjee Rabindranath 
Published: April 2007

AbstractNew dimeric nickel(II) and copper(II) complexes [(L)Ni(μ‐L′)]2[ClO4]2 1 and [(L)Cu(μ‐L′)]2[ClO4]2 2, [2‐[3‐(2′‐pyridyl)pyrazol‐1‐ylmethyl]pyridine (L) and 3‐(2‐pyridyl)pyrazole (HL′)] have been synthesized, structurally characterized, and their absorption, magnetic, EPR and redox properties investigated. The crystal structure of 1·MeCN reveals a planar {Ni2(μ‐L′)2}2+ core [Ni···Ni separation: 4.0765(10) Å] in which each distorted octahedral NiII ions is terminally coordinated by a tridentate ligand L and bridged by two HL′ units, in their deprotonated form. The structural analysis of 2·2MeCN reveals two five‐coordinate CuII ions, each terminally coordinated by adopting only a bidentate coordination mode of L, in which the –CH2py arm remains uncoordinated. A similar bridging [Cu···Cu separation: 3.9382(24) Å] as in 1·MeCN is observed. Thus stereoelectronic preferences of NiII and CuII are clearly revealed. Closer inspection of crystal packing diagram of 1·MeCN reveals the formation of 2‐D network structure assembled solely via C–H···π interaction [pyridyl C–H (4‐position) of pyridylpyrazole unit of L and π cloud of pyridine of bridging deprotonated L′ unit]. In 2·2MeCN, however, π···π interactions between uncoordinated pyridyl arms are observed. Variable‐temperature magnetic studies on both complexes indicate the existence of strong antiferromagnetic coupling between the two metal ions (singlet‐triplet energy separation, J = –20 cm–1 for 1 and –200 cm–1 for 2). When investigated by cyclic voltammetry complex 1 displays two quasi‐reversible electron‐transfer reactions at E1/2 = 1.36 V (ΔEp = 110 mV) and 1.79 V (ΔEp = 120 mV) vs. SCE, due to NiIIINiII/NiII2 and NiIII2/NiIIINiII redox processes, respectively. Constant potential electrolysis at 1.50 V vs. SCE leads to the generation of dark green mixed‐valence NiIIINiII species, which is stable enough to be subjected to characterization by UV/Vis and EPR spectroscopy. Compound 2 exhibits only irreversible reductions (cathodic peak potential, Epc = –0.28 V and –0.50 V vs. SCE).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Stabilizing Factors for Vanadium(IV) in Amavadin
Authors: Hubregtse Ton , Hanefeld Ulf , Arends Isabel W. C. E. 
Published: April 2007

AbstractSix secondary N‐hydroxy amino acids (amavadin‐based ligands) have been prepared through a strategy with nitrone reduction as its key step. Two of these amino acids are the new amavadin ligand analogues 4a and 4b containing either a phenyl or a benzyl group in combination with a small backbone substituent. In addition, the monoester 5 of the amavadin ligand as well as three N‐alkylated N‐hydroxy aminoacids 6 were prepared. Complexation studies with the new tri‐ and bidentate ligands using HRMS revealed that only amavadin and its two analogues with ligands 4a and 4b are stable in aqueous and aerobic environments and that the complexation of vanadium(IV) with ligands 5 and 6 does not lead to air‐stable vanadium(IV) non‐oxo compounds. An interesting spin‐off of the synthetic work on nitrones is an effective and easily applicable method for the synthesis of racemic N‐hydroxy amino acid esters. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Rapid Preparation of 3‐Deoxyanthocyanidins and Novel Dicationic Derivatives: New Insight into an Old Procedure
Authors: Chassaing Stefan , Kueny‐Stotz Marie , Isorez Géraldine , Brouillard Raymond 
Published: April 2007

AbstractCommon 3‐deoxyanthocyanidins and original dicationic flavylium‐benzopyrylium derivatives are easily and efficiently synthesized through reactions between the corresponding phenols and aryl ethynyl ketones in the presence of aqueous hexafluorophosphoric acid. The mechanism of the reaction is discussed and two competitive pathways are consistent with our results.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Signalling Mechanisms in Anion‐Responsive Push‐Pull Chromophores: The Hydrogen‐Bonding, Deprotonation and Anion‐Exchange Chemistry of Functionalized Azo Dyes
Authors: Ros‐Lis José V. , Martínez‐Máñez Ramón , Sancenón Félix , Soto Juan , Rurack Knut , Weißhoff Hardy 
Published: April 2007

AbstractA family of azo dyes containing amide (1), urea (2), thiourea (3), carbamate (4) or amino (5) hydrogen‐bond donating groups were synthesized and their response toward anions was studied. Acetonitrile solutions of 1–5 show bright yellow colours, due to charge‐transfer bands in the 375–400 nm region, slightly modulated by the electron donor strength of the group attached to the 4′ end of the 4‐nitroazobenzene scaffold. Anions of different shape and size (i.e., spherical F–,Cl–, Br– and I–, planar and tetrahedral oxoanions such as NO3–, H2PO4– and HSO4–, carboxylates such as acetate and benzoate and the linear anions cyanide and thiocyanate) were employed in the recognition studies. Two different effects were distinguished: (i) bathochromic shifts of <40 nm to pale orange, due to anion coordination, and (ii) strong red shifts of ca. 200 nm with a concomitant colour change to blue, due to deprotonation. This behaviour was explained as a balance between the deprotonation tendency of the binding sites in the different receptors and the proton affinities of the anions. Semiempirical calculations were carried out to evaluate the hydrogen bond‐donating abilities of the anions and the dyes and a good correlation with the experimentally found values was observed. Stability constants for the receptor–anion complexes were determined spectrophotometrically and the different responses toward fluoride and acetate were assessed by NMR titration experiments. Finally, as a special case, we also report the use of this family of compounds as colorimetric carbon dioxide sensors through reaction with the unprotonated forms of the azo dyes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Substituent Effects of the Alkyl Groups: Polarity vs. Polarizability
Authors: Exner Otto , Böhm Stanislav 
Published: April 2007

AbstractSubstituents effects of the alkyl groups, both straight‐chain and branched, were evaluated by means of model reaction series, each comparing the acidities and basicities of the same or very similar compounds. Four such models wereexamined, one based on known gas‐phase experimental data (acidity and basicity of alcohols), the three others on density‐functional calculations at the levels B3LYP/6‐311++G(2df,2pd)//B3LYP/6‐311++G(2df,2pd) or B3LYP/6‐311+G(d,p)//B3LYP/6‐311+G(d,p): acidity and basicity of 4‐substituted bicyclo[2.2.2]octan‐1‐ols, stability of borate anions compared to the stability of ammonium cations, and acidity of imines compared to the basicity of ketones. In all cases the alkyl groups stabilize both the anions and cations; with straight‐chain alkyls the effect is proportional and can be called polarizability effect. However, simple mathematical expression of the polarizability is not correct because the effect on the cations is always stronger than on the anions. Effects of secondary and tertiary alkyls, in some cases also of branched primary alkyls, are different and deviate from the proportionality. They can be interpreted in some cases as steric effects or hyperconjugation. In any case they are different from the effects of straight‐chain alkyls and they are also fundamentally different from the effects of dipolar substituents; both groups should not be correlated together in one reaction series.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
1,3‐Chirality Transfer by Fragmentation of Allylsulfinic Acids: A Diastereoselective Approach to Vinyl Bromides Related to trans‐Hydrindane or trans‐Decalin
Authors: Chochrek Paweł , Wicha Jerzy 
Published: April 2007

AbstractDiastereoselective approaches to vinyl bromides from bromoallylic alcohols by fragmentation of the respective allylsulfinic acids have been investigated. Bromoallylic alcohols 1a and 6 were transformed into the respective 1,3‐benzothiazol‐2‐yl sulfides 2a and 7 by the Mitsunobu inversion reaction under modified conditions. The sulfides were then oxidized into sulfones 11a and 12a, respectively. Reduction of 11a and 12a with sodium borohydride gave the respective allylsulfinic acid salts 13a and 15 which, without isolation, were treated with aqeous tartaric acid. The salt 13a gave exclusively 5α‐cholestane derivative 14a whereas 15 provided a mixture of the 5α and 5β derivatives 16 and 17 (after deprotection), the former prevailing. In an alternative approach, benzothiazolyl sulfides 2a and 7 were treated sequentially with BH3·THF and LiAlH4 to give thiols 18a and 19a, respectively. Oxidation of thiols 18a and 19a with oxaziridine 21 gave the respective sulfinic acids which, on gentle heating, afforded bromoolefins 14a and 22a, respectively, as the only products. Analogous reaction sequences starting from allylic alcohols devoid of the bromine substituent 1b and 8 have also been studied.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)