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B
Kinds of B Terms modified by B Selected AbstractsControlled cationic polymerization of cyclopentadiene with B(C6F5)3 as a coinitiator in the presence of waterJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2008Sergei V. Kostjuk Abstract The controlled cationic polymerization of cyclopentadiene (CPD) at 20 °C using 1-(4-methoxyphenyl)ethanol (1)/B(C6F5)3 initiating system in the presence of fairly large amount of water is reported. The number,average molecular weights of the obtained polymers increased in direct proportion to monomer conversion in agreement with calculated values and were inversely proportional to initiator concentration, while the molecular weight distribution slightly broadened during the polymerization (Mw/Mn , 1.15,1.60). 1H NMR analyses confirmed that the polymerization proceeds via reversible activation of the COH bond derived from the initiator to generate the growing cationic species, although some loss of hydroxyl functionality happened in the course of the polymerization. It was also shown that the enchainment in cationic polymerization of CPD was affected by the nature of the solvent(s): for instance, polymers with high regioselectivity ([1,4] up to 70%) were obtained in acetonitrile, whereas lower values (around 60%) were found in CH2Cl2/CH3CN mixtures. Aqueous suspension polymerization of CPD using the same initiating system was successfully performed and allowed to synthesize primarily hydroxyl-terminated oligomers (Fn = 0.8,0.9) with Mn , 1000 g mol,1 and broad MWD (Mw/Mn , 2.2). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4734,4747, 2008 [source] Titanium Diboride,Tungsten Diboride Solid Solutions Formed by Induction-Field-Activated Combustion SynthesisJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2003Masachika Shibuya Solid solutions of titanium diboride,tungsten diboride (TiB2,WB2) were synthesized by induction-field-activated combustion synthesis (IFACS) using elemental reactants. In sharp contrast to conventional methods, solid solutions could be formed by the IFACS method within a very short time, ,2 min. Solutions with compositions ranging from 40,60 mol% WB2 were synthesized with a stoichiometric ratio (Ti + W)/B =½; however, samples with excess boron were also made to counter the loss of boron by evaporation. The dependence of the lattice constants of the resulting solid solutions on composition was determined. The "a" parameter decreased only slightly with an increase in the WB2 content, whereas the "c" parameter exhibited a significant decrease over the range 40,60 mol% WB2. Solid-solution powders formed by the IFACS method were subsequently sintered in a spark plasma sintering (SPS) apparatus. After 10 min at 1800°C, the samples densified to relative density 86%. XRD analysis showed the presence of only the solid-solution phase. [source] ChemInform Abstract: Intramolecular Aldol Reaction of N-Acylated (2-Aminophenyl)-,-oxoacetic Acids: Rapid Access to Tri- and Tetracyclic 1,2-Dihydroquinolin-2(1H)-ones.CHEMINFORM, Issue 37 2010Malik Hellal Abstract All substrates are prepared following the sequence A)/B) shown for examples (III). [source] Modified TEI Index: A Promising Parameter in Essential Hypertension?ECHOCARDIOGRAPHY, Issue 4 2005Nurgül Keser M.D. Purpose: Modified TEI index is pointed to be more effective in the evaluation of global cardiac functions compared to systolic and diastolic measurements alone. We planned to determine its applicability in hypertension and relation with left ventricular mass index (LVMI). Methods: We studied 48 patients with mild/moderate hypertension and normal coronary angiograms. In total 22 patients (12 men, 10 women, mean age: 55 ± 6) with normal LVMI were studied in group I, 26 patients (12 men, 14 women, mean age: 57 ± 7) with increased LVMI in group II, and 20 patients (10 men, 10 women, mean age: 53 ± 7) with normal blood pressure as a control group. Standard 2D, Doppler, and mitral annulus pulse wave tissue Doppler were used for all measurements. Modified TEI index was calculated as diastolic time interval measured from end of Am wave to origin of Em (a,) minus systolic Sm duration (b,) divided by b(a,,b,/b,). Results: Modified TEI index was significantly higher in both groups than normal group and in group II than in group I. (Control group: 0.33 ± 0.05, group I: 0.51 ± 0.17, group II: 0.68 ± 0.16, P< 0.0001). Conclusion: Modified TEI index, a marker of left ventricular systolic and diastolic functions, is impaired in hypertensives before hypertrophy develops and impairment is more prominent in hypertrophy. Therefore, (1) modified TEI index in hypertensives is a safe, feasible, and sensitive index for evaluation of global ventricular functions. (2) Evaluation of hypertensives with this index periodically may guide interventions directed toward saving systolic and diastolic functions. (3) Modified TEI index is gaining importance as a complementary parameter to standard Doppler or in cases where standard Doppler has its limitations. [source] Effects of organic fertilisers and irrigation level on physical and chemical quality of industrial tomato fruit (cv. Nautilus)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2009Ramón Madrid Abstract BACKGROUND: The objective of this work was to study the influence of irrigation and organic fertilisation on quality attributes of tomato fruit (cv. Nautilus) grown for the canning industry. The assay was carried out during two consecutive years (2006 and 2007) in agricultural soil. Nine treatments resulting from the combination of three fertilisation types (sheep manure, a mixture of sheep manure and peat and an inorganic fertiliser (control)) with three levels of drip irrigation (3.30, 5.00 and 6.70 mm day,1) under black polyethylene mulch were applied (n = 3). RESULTS: For the chromatic attributes L*, H*, C* and S* the highest values corresponded to the treatments with organic matter. However, the a*/b* ratio and colour index value were higher for the control treatment. In all cases the estimated optimal ripening time was the same, and on this date a decline in the ratios was observed. The values of the physical properties increased with increasing irrigation, higher values always being obtained in the treatments with organic fertilisers. The highest production for all irrigation levels corresponded to the treatment with mixed sheep manure and peat fertiliser. CONCLUSION: Cultivation involving fertilisation with the manure/peat mixture and an irrigation level slightly above 5.00 mm day,1 can be recommended as optimal, since it gave the most satisfactory values with respect to the quality attributes of tomato fruit grown for the canning industry. Copyright © 2009 Society of Chemical Industry [source] Effect of the types and concentrations of alkali on the color of cocoa liquorJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2009Pablo Rodríguez Abstract BACKGROUND: The alkalization process is extensively used in the cocoa industry, but information is scarce and not easy to acquire. The goal of the study was to evaluate the effect of different types and concentrations of alkali on the color of cocoa liquor. Dried beans from Chuao (state Aragua, Venezuela) were used to produce cocoa liquors. Samples of liquors were alkalized with solutions of NaHCO3, Na2CO3 and NaOH at concentrations of 10, 20 and 30 g kg,1. RESULTS: The data showed that values of the coordinates L*, a* and b* decrease when liquors were treated with the three different types and concentrations of alkalis. Almost all samples had ,E* values above 1. The ratios b*/a* and a*/b* and the proximate composition were also modified. Crude protein, crude fat and polyphenol concentrations were decreased and the ash content augmented as concentrations of the alkalis were increased. The fatty acid and sugar profiles were also affected. These ratios were most pronounced when NaOH was used. CONCLUSION: The selection of the type or concentration of alkali is a function of the type of product to be elaborated. Copyright © 2009 Society of Chemical Industry [source] Comparison of physicochemical, microscopic and sensory characteristics of ecologically and conventionally grown crops of two cultivars of tomato (Lycopersicon esculentum Mill.)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2009Luis Eduardo Ordóñez-Santos Abstract BACKGROUND: Numerous studies have compared ecologically produced foods with conventionally produced competitors, with contradictory results. In this work we investigated the physicochemical, microscopic and sensory properties of two tomato cultivars (Lladó and Antillas), which were grown both ecologically and conventionally. RESULTS: The physicochemical variables size, weight, firmness, total acidity, pH, total solids content, lycopene content and CIELab a*, b*, a*/b*, C* and h* were all significantly influenced by cultivar, as were the sensory variables external colour, internal colour, external aroma intensity and flavour persistence. Compared with conventionally grown tomatoes, ecologically grown tomatoes had larger total solids contents and larger values of the CIELab colour parameters b*, C* and h*, but smaller sizes and weights and smaller values of the CIELab parameter ratio a*/b*; however, these physicochemical differences were insufficient for growing method to have a significant influence on any of the sensory attributes that were evaluated. Microscopy showed the influence of cultivar on lycopene content, but no other structural differences were observed between the two cultivars or between tomatoes grown by different methods. CONCLUSIONS: The statistically significant differences found in this study were mainly between cultivars rather than between tomatoes grown using different management practices. Copyright © 2009 Society of Chemical Industry [source] Comparative effect of red yeast rice (Monascus purpureus), red beet root (Beta vulgaris) and betanin (E-162) on colour and consumer acceptability of fresh pork sausages packaged in a modified atmosphereJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2006Luis Martínez Abstract Fresh pork sausages containing natural colorants, red yeast rice powder (Monascus purpureus; Frame®) or a crude red beet root (Beta vulgaris) juice or commercial betanin (E-162), at different concentrations, were packaged in an atmosphere containing 80% O2 and 20% CO2 and stored in the dark for 20 days. The following parameters were measured at 4 day intervals: instrumental colour (CIE L*, a*, b*, a*/b*, C* and h*), reflectance spectra, sensory discoloration (trained panel) and acceptability and willingness to purchase (habitual and non-habitual consumer panels) under two different lighting displays (standard fluorescent and Promolux® lamp). The use of colorants improved the colour properties of fresh pork sausages. Sausages with red yeast rice, red beet root juice and betanin had lower L* and h* and higher a* and a*/b* values than control samples. The colour properties of sausages with red beet root were the closest to control sausages, while sausages with red yeast rice had significantly lower b* values. Both natural colorants and betanin protected sausages from discoloration and extended acceptability and willingness to purchase by about 4 days, according to evaluation by habitual consumers under two different types of lighting display. Therefore, red beet root juice may be envisaged as the most suitable natural colorant for use in fresh pork sausages. Copyright © 2005 Society of Chemical Industry [source] Effect of freezing/thawing conditions and long-term frozen storage on the quality of mashed potatoesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2005M Dolores Álvarez Abstract The effects of freezing temperature (,80, ,40 or ,24 °C) and thawing mode (microwave or overnight at 4 °C) on quality parameters of mashed potatoes made from tubers (cv Kennebec) and from potato flakes were examined, as was the effect of long-term frozen storage on the quality of mashed potatoes. Mashed potatoes were tested for texture profile analysis (TPA) and cone penetration, oscillatory and steady rheometry, colour, dry matter, Brix and sensory analyses. In natural mashed potatoes, TPA hardness and oscillatory parameters showed that processing resulted in a softer product than the fresh control. The parameters were lower in the samples thawed at 4 °C than in those thawed by microwave at all the freezing temperatures used, which may be ascribed to gelatinisation of the starch released from damaged cells. Differences from the freshly prepared product decreased when the samples were frozen at ,80 °C and thawed by microwave. No difference was found in sensory acceptability between samples frozen at ,80 and ,40 °C, which probably reflects the panellists' mixed preferences for air-thawed versus microwave-thawed samples. Increasing the time in frozen storage led to a natural mash with a firmer texture, higher L*/b* value and Brix; nonetheless, panellists found the samples at 0, 3 and 12 months of frozen storage equally acceptable. In commercial mash, penetration and oscillatory parameters showed that processing made for a firmer product than the fresh control, probably owing to retrogradation of gelatinised starch. Thawing mode had a significant effect on parameters, which were lower in the samples thawed at 4 °C. The structure and quality of commercial mash was more detrimentally affected by freezing and, therefore, we would not recommend either freezing or frozen storage of this mashed potato in the used conditions. Natural mash made from Kennebec potatoes should be frozen quickly and thawed by microwave in the conditions described to obtain a product more similar to that freshly made. If the samples are frozen by air blasting at ,40 °C, the product can withstand frozen storage for one year. Copyright © 2005 Society of Chemical Industry [source] The PSCz dipole revisitedMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2006Spyros Basilakos ABSTRACT We re-examine the gravitational acceleration (dipole) induced on the Local Group of galaxies by the Infrared Astronomical Satellite (IRAS) galaxy distribution of the Point Source Catalog redshift (PSCz) survey. We treat the cirrus-affected low galactic latitudes by utilizing a spherical harmonic expansion of the galaxy surface density field up to the octapole order. We find strong indications for significant contributions to the Local Group motion from depths up to ,185 h,1 Mpc and a possible contribution even from ,210 h,1 Mpc, in agreement with the recent analysis of Kocevski & Ebeling of a whole-sky X-ray cluster survey. What changes with respect to the previous PSCz dipole analyses is: (i) the large-scale dipole contributions and (ii) an increase of the overall dipole amplitude due to the important contribution of the local volume (, 4 h,1 Mpc), which we now take into account. This results in a lower value of the , (,,0.6m/b) parameter, which we find to be ,IRAS, 0.49 in real space. Therefore, for the concordance cosmological model (,m= 1 ,,,= 0.3), the IRAS galaxies bias factor is bIRAS, 1, which means that IRAS galaxies are good tracers of the underlying matter distribution. [source] Consistent , values from density,density and velocity,velocity comparisonsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2002Saleem Zaroubi Abstract We apply a new algorithm, called the unbiased minimal variance (hereafter UMV) estimator, to reconstruct the cosmic density and peculiar velocity fields in our local Universe from the SEcat catalogue of peculiar velocities comprising both early- (ENEAR) and late-type (SFI) galaxies. The reconstructed fields are compared with those predicted from the IRAS PSCz galaxy redshift survey to constrain the value of ,=,0.6m/b, where ,m and b are the mass density and the bias parameters. The comparison of the density and velocity fields is carried out within the same methodological framework, and leads, for the first time, to consistent values of ,, yielding ,= 0.57+0.11,0.13 and ,= 0.51 ± 0.06, respectively. We find that the distribution of the density and velocity residuals, relative to their respective errors, is consistent with a Gaussian distribution with ,, 1, indicating that the density field predicted from the PSCz is an acceptable fit to that deduced from the peculiar velocities of the SEcat galaxies. [source] Non-commutative field theories beyond perturbation theoryFORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 7-8 2003W. Bietenholz We investigate two models in non-commutative (NC) field theory by means of Monte Carlo simulations. Even if we start from the Euclidean lattice formulation, such simulations are only feasible after mapping the systems onto dimensionally reduced matrix models. Using this technique, we measure Wilson loops in 2d NC gauge theory of rank 1. It turns out that they are non-perturbatively renormalizable, and the phase follows an Aharonov-Bohm effect if we identify , = 1/B. Next we study the 3d , ,4 model with two NC coordinates, where we present new results for the correlators and the dispersion relation. We further reveal the explicit phase diagram. The ordered regime splits into a uniform and a striped phase, as it was qualitatively conjectured before. We also confirm the recent observation by Ambjø rn and Catterall that such stripes occur even in d = 2, although they imply the spontaneous breaking of translation symmetry. However, in d = 3 and d = 2 we observe only patterns of two stripes to be stable in the range of parameters investigated. [source] Syntheses and Coordination Chemistry of Aminomethylphosphine Derivatives of AdenineEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2003Qingzhi Zhang Abstract Two aminomethylphosphane derivatives of adenine 9-(2-{bis[(diphenylphosphanyl)methyl]amino}ethyl)adenine (La) and 9-(3-{bis[(diphenylphosphanyl)methyl]amino}propyl)adenine (Lb) were synthesised. Oxidation of La and Lb with H2O2, elemental sulfur or elemental selenium led to the corresponding oxidized products 4a/b,6a/b. Both La and Lb behave as didentate ligands towards late transition metals. Reaction of La or Lb with [MX2(cod)] (M = Pd, Pt; X = Cl, Me) gave chelate complexes 7a/b,10a/b. Reaction of La or Lb with [AuCl(tht)] or [{RuCl(,-Cl)(p -MeC6H4iPr)}2] gave the didentate bridging complexes 11a/b and 12a. All compounds have been fully characterised by microanalysis, IR, 1H and 31P{1H} NMR spectroscopy, and EI/CI/FAB mass spectrometry. 1H{31P} NMR and 1H- 13C correlation experiments were used to confirm the spectral assignments where necessary. Two compounds were structurally characterised by X-ray crystallographic analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Laser Flash Photolysis of Disulfonyldiazomethanes: Partitioning between Hetero-Wolff Rearrangement and Intramolecular Carbene Oxidation by a Sulfonyl GroupEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2003Götz Bucher Abstract Laser flash photolysis of bis(phenylsulfonyl)diazomethane (1a) and ditosyldiazomethane (1b) leads to the formation of sulfonylsulfenes 8a/8b (,max = 310 nm). Non-first-order kinetics and non-linear Stern,Volmer behavior suggest the formation of another transient species also absorbing at , = 310 nm. Based on the results of DFT calculations, these species are tentatively identified as dithiocarbonate S,S,S, -trioxides 12a/b, which are formed from the oxathiirene S -oxides 9a/b. The latter compounds bear the characteristics of masked carbenes (, estimated as 700 ps) and are quenched by methanol and cyclooctene. Singlet disulfonylcarbenes 2a/b are not predicted to be minima, since all attempts at optimizing the geometry of 2a led to 9a instead. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Structure,Activity Relationship Studies in Single-Site Esterase Peptide DendrimersISRAEL JOURNAL OF CHEMISTRY, Issue 1 2009Sacha Javor We recently reported on peptide dendrimers with a single catalytic site at the dendrimer core catalyzing the hydrolysis of acetoxy- and butyryloxy-pyrene trisulfonate 1a/b in aqueous buffer with Michaelis,Menten kinetics. Substrate binding is mediated by a pair of protonated arginine or histidine residues in the first generation branch, and esterolysis is performed by the imidazole side-chain of a histidine residue in the core acting as a general base or nucleophile. Herein we report on a structure,activity relationship study searching for an optimal combination between amino acid sequence and catalytic machinery. Installation of histidine residues onto the aromatic dendrimer framework "R" leads to 10-fold higher rate acceleration up to kcat/kuncat = 1.5 * 103 at pH 5.5 with dendrimers RG3H (AcYT)8 (BWG)4 (BHS)2BHS and RMG3H (AcYT)8(BWG)4(BHSG)2BHS (one-letter codes for L -amino acids; Ac = acetyl, B = L -2,3-diaminopropionic acid branching point, C-terminus is amide -CONH2). These dendrimers reach the compactness of a native folded protein. [source] Cellular and subcellular localization of the GABAB receptor 1a/b subunit in the rat periaqueductal gray matterTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 5 2007Paolo Barbaresi Abstract The inhibitory effects of ,-aminobutyric acid (GABA)ergic neurotransmission in the periaqueductal gray matter (PAG) are mediated, at least partly, by metabotropic GABAB receptor subtypes whose cellular and subcellular localization is still unknown. We performed immunohistochemical experiments with an antibody against GABAB receptor subtype 1a/b (GABABR1a/b) by using light and electron microscopy. On light microscopy, GABABR1a/b immunoreactivity (IR) was in all columns, defined by cytochrome oxidase histochemistry. Neuropil labeling was strongest in the lateral portion of dorsolateral PAG. Labeled neurons, albeit not numerous, were in ventrolateral, dorsal, and medial subdivisions and were sparser in dorsolateral PAG. Labeling was mostly on the soma of PAG neurons. Sometimes GABABR1a/b IR spread along proximal dendrites; in these cases bipolar neurons were the most common type. On electron microscopy, GABABR1a/b IR was mainly on dendrites (54.92% of labeled elements) and axon terminals (21.90%) making synapses with labeled and unlabeled postsynaptic elements. Presynaptic labeling was also on unmyelinated and myelinated axons (overall 8% of all labeled elements). Postsynaptically, GABABR1a/b IR was at extrasynaptic sites on dendritic shafts; spines were always unlabeled. On axon terminals, GABABR1a/b IR was on extrasynaptic membranes and sometimes on presynaptic membrane specializations. Of the labeled elements, 13.03% elements were distal astrocytic processes (dAsPs) surrounding both symmetric and asymmetric synapses whose pre- and postsynaptic elements were often labeled. Immunoreactive dAsPs were around the soma and dendrites of both labeled and unlabeled neurons. These findings provide insights into the intrinsic PAG organization and suggest that presynaptic, postsynaptic, and glial GABAB receptors may play crucial roles in controlling PAG neuronal activity. J. Comp. Neurol. 505:478,492, 2007. © 2007 Wiley-Liss, Inc. [source] Laser Flash Photolysis of Disulfonyldiazomethanes: Partitioning between Hetero-Wolff Rearrangement and Intramolecular Carbene Oxidation by a Sulfonyl GroupEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2003Götz Bucher Abstract Laser flash photolysis of bis(phenylsulfonyl)diazomethane (1a) and ditosyldiazomethane (1b) leads to the formation of sulfonylsulfenes 8a/8b (,max = 310 nm). Non-first-order kinetics and non-linear Stern,Volmer behavior suggest the formation of another transient species also absorbing at , = 310 nm. Based on the results of DFT calculations, these species are tentatively identified as dithiocarbonate S,S,S, -trioxides 12a/b, which are formed from the oxathiirene S -oxides 9a/b. The latter compounds bear the characteristics of masked carbenes (, estimated as 700 ps) and are quenched by methanol and cyclooctene. Singlet disulfonylcarbenes 2a/b are not predicted to be minima, since all attempts at optimizing the geometry of 2a led to 9a instead. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Syntheses and Coordination Chemistry of Aminomethylphosphine Derivatives of AdenineEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2003Qingzhi Zhang Abstract Two aminomethylphosphane derivatives of adenine 9-(2-{bis[(diphenylphosphanyl)methyl]amino}ethyl)adenine (La) and 9-(3-{bis[(diphenylphosphanyl)methyl]amino}propyl)adenine (Lb) were synthesised. Oxidation of La and Lb with H2O2, elemental sulfur or elemental selenium led to the corresponding oxidized products 4a/b,6a/b. Both La and Lb behave as didentate ligands towards late transition metals. Reaction of La or Lb with [MX2(cod)] (M = Pd, Pt; X = Cl, Me) gave chelate complexes 7a/b,10a/b. Reaction of La or Lb with [AuCl(tht)] or [{RuCl(,-Cl)(p -MeC6H4iPr)}2] gave the didentate bridging complexes 11a/b and 12a. All compounds have been fully characterised by microanalysis, IR, 1H and 31P{1H} NMR spectroscopy, and EI/CI/FAB mass spectrometry. 1H{31P} NMR and 1H- 13C correlation experiments were used to confirm the spectral assignments where necessary. Two compounds were structurally characterised by X-ray crystallographic analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] New Approaches to 12-Coordination: Structural Consequences of Steric Stress, Lanthanoid Contraction and Hydrogen BondingEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2010Anthony S. R. Chesman Abstract The anionic dinitrile ligand dicyanonitrosomethanide (dcnm), C(CN)2(NO),, and the anion resulting from its addition product with water, carbamoylcyanonitrosomethanide (ccnm), C(CN)(CONH2)(NO),, have been incorporated into lanthanoid complexes and display unusual ,2(N,O) nitroso coordination modes. (Et4N)3[Ln(ccnm)6] (1Ln; 1Ln = 1La, 1Ce, 1Pr, 1Nd, 1Sm) and (Me4N)3[Ln(ccnm)6] (2Ln; 2Ln = 2La, 2Ce, 2Pr, 2Nd) are systems containing 12-coordinate homoleptic trianionic lanthanoidate complexes. The nitroso groups of the ccnm ligands form three-membered ring chelates with the lanthanoid metal centre, with the asymmetry of the nitroso ,2 interactions dependent upon the intramolecular N,H···O=N hydrogen bonding. Additional intermolecular hydrogen bonding interactions exist between adjacent amide and nitrile groups giving rise to 3D ,-Po and 6,8-connected (412.63)(420.68) networks in 1Ln and 2Ln, respectively. The compounds (Me4N)3[Ln(dcnm)6] (3Ln; 3Ln = 3La, 3Ce, 3Nd, 3Sm) also contain a 12-coordinate trianionic lanthanoidate complex with the nitroso group exhibiting a highly symmetrical ,2 interaction. The sterically crowded environments of [Ln(18-crown-6)(dcnm)3] (4Ln; 4Ln = 4La, 4Ce, 4Pr, 4Nd) result in a shift towards a more asymmetric ,2 bonding of the nitroso group with decrease in the Ln3+ radius. There is a corresponding increase of the Ln,O,N angle, and one ligand is ,1(O) binding in 4Nd. The dcnm ligands in the discrete complexes [La(phen)3(dcnm)(3,x)Clx], x , 0.25 (5) (phen = 1,10-phenanthroline), (Et4N)[Ce(phen)2(dcnm)4] (6a/b, 6c) and [Ce(phen)2(dcnm)Cl2H2O] (7) display a variety of coordination modes. Complex 5 has 1D chains formed by ,,, stacking of adjacent phen co-ligands. Complexes 6 contain the monoanionic complex [Ce(phen)2(dcnm)4], with two geometric isomers present in the crystal structure of 6a/b. Complex 7 forms extended 1D chains via hydrogen bonding between coordinated water and chloride atoms and an extensive array of face-to-face , interactions. [source] Syntheses and Coordination Chemistry of Aminomethylphosphine Derivatives of AdenineEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2003Qingzhi Zhang Abstract Two aminomethylphosphane derivatives of adenine 9-(2-{bis[(diphenylphosphanyl)methyl]amino}ethyl)adenine (La) and 9-(3-{bis[(diphenylphosphanyl)methyl]amino}propyl)adenine (Lb) were synthesised. Oxidation of La and Lb with H2O2, elemental sulfur or elemental selenium led to the corresponding oxidized products 4a/b,6a/b. Both La and Lb behave as didentate ligands towards late transition metals. Reaction of La or Lb with [MX2(cod)] (M = Pd, Pt; X = Cl, Me) gave chelate complexes 7a/b,10a/b. Reaction of La or Lb with [AuCl(tht)] or [{RuCl(,-Cl)(p -MeC6H4iPr)}2] gave the didentate bridging complexes 11a/b and 12a. All compounds have been fully characterised by microanalysis, IR, 1H and 31P{1H} NMR spectroscopy, and EI/CI/FAB mass spectrometry. 1H{31P} NMR and 1H- 13C correlation experiments were used to confirm the spectral assignments where necessary. Two compounds were structurally characterised by X-ray crystallographic analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Genetic polymorphism of N -acetyltransferase 2 in the susceptibility to laryngeal squamous cell carcinomaHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 12 2005Murat Ünal MD Abstract Background. The purpose of this study was to investigate whether polymorphism of N -acetyltransferase 2 (NAT2) genotypes are associated with the risk of laryngeal squamous cell carcinoma (SCC). Methods. The study group consisted of 45 white patients with laryngeal SCC (42 men, with a mean age of 54 years [range, 37,70 years] and three women, with a mean age of 47 years [range, 32,55 years]) and 104 control subjects (68 men and 36 women; mean age, 50 years; range, 28,73 years). All of the patients were primarily treated with surgical intervention. Blood samples (5 mL) were obtained before surgery or from the patients under follow-up to 5 years after surgery (mean follow-up, 27 months; range, 6,48 months). DNA was extracted from the lymphocytes by high pure template preparation kit. NAT2*5A, NAT2*6A, NAT2*7A/B, and NAT2*14A were detected by use of LightCycler- NAT2 mutation detection kit by real-time polymerase chain reaction with Light Cycler instruments. The association between NAT2 polymorphisms and laryngeal SCC was prospectively modeled through multivariate logistic regression analysis. Results. We found that the risk of laryngeal SCC was 7.3-fold higher in individuals with NAT2*5 mutant allele, 3.8-fold higher in subjects with NAT2*6 heterozygote allele, and 38.3-fold higher in NAT2*6 mutant allele. We also found that individuals with NAT2*7 heterozygote allele had a 0.2-fold less risk for the development of laryngeal SCC (p = .018). Conclusion. In this population, patients with NAT2*5 mutant and *6 heterozygous and mutant genotypes had a significantly higher risk for development of laryngeal SCC. © 2005 Wiley Periodicals, Inc. Head Neck27: XXX,XXX, 2005 [source] Syntheses and Coordination Chemistry of Aminomethylphosphine Derivatives of AdenineEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2003Qingzhi Zhang Abstract Two aminomethylphosphane derivatives of adenine 9-(2-{bis[(diphenylphosphanyl)methyl]amino}ethyl)adenine (La) and 9-(3-{bis[(diphenylphosphanyl)methyl]amino}propyl)adenine (Lb) were synthesised. Oxidation of La and Lb with H2O2, elemental sulfur or elemental selenium led to the corresponding oxidized products 4a/b,6a/b. Both La and Lb behave as didentate ligands towards late transition metals. Reaction of La or Lb with [MX2(cod)] (M = Pd, Pt; X = Cl, Me) gave chelate complexes 7a/b,10a/b. Reaction of La or Lb with [AuCl(tht)] or [{RuCl(,-Cl)(p -MeC6H4iPr)}2] gave the didentate bridging complexes 11a/b and 12a. All compounds have been fully characterised by microanalysis, IR, 1H and 31P{1H} NMR spectroscopy, and EI/CI/FAB mass spectrometry. 1H{31P} NMR and 1H- 13C correlation experiments were used to confirm the spectral assignments where necessary. Two compounds were structurally characterised by X-ray crystallographic analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Laser Flash Photolysis of Disulfonyldiazomethanes: Partitioning between Hetero-Wolff Rearrangement and Intramolecular Carbene Oxidation by a Sulfonyl GroupEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2003Götz Bucher Abstract Laser flash photolysis of bis(phenylsulfonyl)diazomethane (1a) and ditosyldiazomethane (1b) leads to the formation of sulfonylsulfenes 8a/8b (,max = 310 nm). Non-first-order kinetics and non-linear Stern,Volmer behavior suggest the formation of another transient species also absorbing at , = 310 nm. Based on the results of DFT calculations, these species are tentatively identified as dithiocarbonate S,S,S, -trioxides 12a/b, which are formed from the oxathiirene S -oxides 9a/b. The latter compounds bear the characteristics of masked carbenes (, estimated as 700 ps) and are quenched by methanol and cyclooctene. Singlet disulfonylcarbenes 2a/b are not predicted to be minima, since all attempts at optimizing the geometry of 2a led to 9a instead. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] GENETIC STUDY: Heritability and a genome-wide linkage analysis of a Type II/B cluster construct for cannabis dependence in an American Indian communityADDICTION BIOLOGY, Issue 3 2009Cindy L. Ehlers ABSTRACT Subtyping of substance dependence disorders holds promise for a number of important research areas including phenotyping for genetic studies, characterizing clinical course, and matching treatment and prevention strategies. This study sought to investigate whether a dichotomous construct similar to Babor's Types A/B and Cloninger's Types I/II for alcohol dependence can be identified for cannabis dependence in a Native American sample. In addition, heritability of this construct and its behavior in a genetic linkage analyses were evaluated. Information on cannabis use and dependence symptoms and other psychiatric disorders was obtained using the Semi-Structured Assessment for the Genetics of Alcoholism from a community sample of 606 American Indians. Hierarchical average linkage and K means cluster analysis was used, and a three-cluster solution was found to generate the best separation of variables. Ninety-one per cent of cannabis-dependent participants fell into one of the two subtypes: Type A/I cluster (n = 114, 56%) and Type B/II cluster (n = 70, 35%). Heritability (estimated using Sequential Oligogenic Linkage Analysis Routines) was only significant for the Type B/II cluster (h2 = 0.44, SE = 0.18, P < 0.01). Evidence for linkage was found for the Type B/II cluster (versus no diagnosis) on chromosome 16 [at 139 centimorgans (cM), Log of the Odds (LOD) score = 4.4], and on chromosome 19 (at 74 cM, LOD score = 6.4). Regions of interest for this phenotype (LOD > 1.5) were also located on chromosomes 14, 21, 22. These findings suggest that a Type B/II cannabis dependence phenotype can be identified in this population and that it is in part heritable and linked to areas of the genome identified previously for drug dependence phenotypes in this population as well as in other studies. [source] Synaptic and non-synaptic mechanisms of amygdala recruitment into temporolimbic epileptiform activitiesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2003Julia Klueva Abstract Lateral amygdala (LA) activity during synchronized-epileptiform discharges in temporolimbic circuits was investigated in rat horizontal slices containing the amygdala, hippocampus (Hip), perirhinal (Prh) and lateral entorhinal (LEnt) cortex, through multiple-site extra- and intracellular recording techniques and measurement of the extracellular K+ concentration. Application of 4-aminopyridine (50 µm) induced epileptiform discharges in all regions under study. Slow interictal-like burst discharges persisted in the Prh/LEnt/LA after disconnection of the Hip, seemed to originate in the Prh as shown from time delay analyses, and often preceded the onset of ictal-like activity. Disconnection of the amygdala resulted in de-synchronization of epileptiform discharges in the LA from those in the Prh/LEnt. Interictal-like activity was intracellularly reflected in LA projection neurons as ,-aminobutyric acid (GABA)A/B receptor-mediated synaptic responses, and depolarizing electrogenic events (spikelets) residing on the initial phase of the GABA response. Spikelets were considered antidromically conducted ectopic action potentials generated at axon terminals, as they were graded in amplitude, were not abolished through hyperpolarizing membrane responses (which effectively blocked evoked orthodromic action potentials), lacked a clear prepotential or synaptic potential, were not affected through blockers of gap junctions, and were blocked through remote application of tetrodotoxin at putative target areas of LA projection neurons. Remote application of a GABAB receptor antagonist facilitated spikelet generation. A transient elevation in the extracellular K+ level averaging 3 mm above baseline occurred in conjunction with interictal-like activity in all areas under study. We conclude that interictal-like discharges in the LA/LEnt/Prh spread in a predictable manner through the synaptic network with the Prh playing a leading role. The rise in extracellular K+ may provide a depolarizing mechanism for recruitment of interneurons and generation of ectopic action potentials at axon terminals of LA projection neurons. Antidromically conducted ectopic action potentials may provide a spreading mechanism of seizure activity mediated by diffuse axonal projections of LA neurons. [source] Domiciliary application of CryoCuff in severe haemophilia: qualitative questionnaire and clinical auditHAEMOPHILIA, Issue 4 2008A. I. D'YOUNG Abstract., The acute management of haemophilic bleeding episodesin the home setting is based on the concept of immediate factor replacement therapy and the PRICE regime , an acronym representing the concepts of Protection, Rest, Ice, Compression and Elevation [1,2]. Integral to this regime is the application of cold therapy, and yet little is known regarding the safe periods of application, or the relative safety of cryotherapy devices such as the CryoCuffÔ when used in the home setting by patients suffering from severe haemophilia and related bleeding disorders. This study examines the subjective patient response to the application of the CryoCuffÔ device in the home setting in terms of the effect on pain, joint swelling and the return to ,pre-bleed status' of the knee, ankle or elbow in patients with severe haemophilia A/B or type III von Willebrand's disease (VWD) immediately following haemarthrosis, and any potential adverse effects related to the device or recommended duration of application as stated in the PRICE guideline (Fig. 1). Twelve patients, either with severe haemophilia A/B or with VWD were recruited and asked to use the CryoCuffÔ device as part of the PRICE regime immediately following the onset of knee-, ankle- or elbow bleeds for the next one year. Each subject was then sent a qualitative questionnaire to determine subjective responses to the device. All patients reported that the application protocol was easy to follow, they were able to apply the device as per the PRICE regime and they were able to tolerate it for the recommended period. Whereas, all the patients felt that the device had a significant impact on alleviation of pain and return to pre-bleed status, 78% of the patients felt that the device led to a significant reduction in swelling around the affected joint. There was no conclusive evidence that the device resulted in any reduction in the amount of factor used to treat the acute bleeding episode, however, no patients reported any perceived delay in achieving haemostasis or required extra factor replacement therapy consequent to the usage of the device. No other adverse effects were reported by participants in this study. Figure 1. ,The qualitative participant questionnaire, given following 1 year of unsupervised use in the home setting immediately following the onset of the symptoms of haemarthroses. [source] Stress kinase p38 mediates EGFR transactivation by hyperosmolar concentrations of sorbitolJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2002Hao Cheng Activation of the epidermal growth factor receptor (EGFR) has been shown to occur by ligand-dependent and ligand-independent mechanisms. Different molecular mechanisms have been found to be responsible for ligand-independent receptor transactivation. Here, we show that hyperosmolar concentrations of sorbitol activate the EGFR in human keratinocytes. Experiments using specific inhibitors of EGFR phosphorylation show that the increased amount of activated receptors is the result of a decreased rate of dephosphorylation. Furthermore, sorbitol treatment results in a strong activation of stress kinase p38. Treatment of the cells with SB203580, a known inhibitor of p38 , and , kinases, results in impairment of receptor activation, indicating that the stress kinase is involved in receptor activation modulation. This is further reinforced by experiments showing that addition of Toxin B, known to be an inhibitor of the small Rho GTPases rac1, cdc42, and Rho A/B, to the cells results in a strong induction of EGFR activation. Our results point, therefore, to a mechanism by which osmotic shock activates EGFR through the small Rho GTPases-p38 stress kinase pathway. © 2002 Wiley-Liss, Inc. [source] Mannose-binding lectin gene polymorphisms in relation to periodontitisJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 11 2008Anna Louropoulou Abstract Aim: To investigate the correlation of six functional polymorphisms in the MBL gene with MBL plasma levels in relation to periodontitis. Material and Methods: A total of 92 periodontitis patients and 70 controls, all of Caucasian origin, were included. Patients and controls were genotyped for the L/H, X/Y, P/Q, A/D, A/B and A/C polymorphisms. Distributions of genotypes, rate of allele carriage and allele frequencies were compared between patients and controls. Patients and controls were subdivided in groups of genotypes. Plasma MBL levels were compared between different genotype groups. Results: On the basis of genotyping, three phenotypes with regard to mannose-binding lectin (MBL) production were distinguished: high-producers, low-producers and deficient subjects. No differences in the genotype frequencies were observed between patients and controls. Within patients and controls, subjects with the high-producing genotypes had significantly higher MBL plasma levels than low-producers and deficient subjects (p<0.001). Plasma MBL was higher in low-producer patients compared with low-producer controls (padjusted=0.021). Conclusion: No association could be observed between MBL gene polymorphisms and susceptibility to periodontitis in Caucasians. However, now that genotyping could distinguish the low producing and deficient subjects from the high-producers, it was observed, for the first time, that MBL acts as a weak acute-phase protein in periodontitis. [source] Effects of Calcination Temperature and A/B Ratio on the Dielectric Properties of (Ba,Ca)(Ti,Zr,Mn)O3 for Multilayer Ceramic Capacitors with Nickel ElectrodesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2000Wen-Hsi Lee The electrical performance of multilayer ceramic capacitors (MLCCs) with Ni inner electrodes, made from (Ba,Ca)(Ti,Zr,Mn)O3 (BCTZM), is closely related to the calcination temperature and the A/B ratio of the powder. For materials showing A/B = 1.000, the lifetime, the breakdown voltage, and the RC increase with higher calcination temperatures. No significant effect of the calcination temperature on RC and lifetime was found for materials showing A/B = 0.991. The isoelectric point of BCTZM is shifted toward higher pH values when the calcination temperature is decreased. The above results are attributed to the colloidal stability of aqueous BCTZM suspensions and the resulting green density of powder compacts. [source] Oral cavity is not a reservoir for Helicobacter pylori in infected patients with functional dyspepsiaMOLECULAR ORAL MICROBIOLOGY, Issue 3 2009V. P. Silva Rossi-Aguiar Introduction:,Helicobacter pylori infection is very prevalent in Brazil, infecting almost 65% of the population. The aim of this study was to evaluate the presence of this bacterium in the oral cavity of patients with functional dyspepsia (epigastric pain syndrome), establish the main sites of infection in the mouth, and assess the frequency of cagA and vacA genotypes of oral H. pylori. Methods:, All 43 outpatients with epigastric pain syndrome, who entered the study, were submitted to upper gastrointestinal endoscopy to rule out organic diseases. Helicobacter pylori infection in the stomach was confirmed by a rapid urease test and urea breath tests. Samples of saliva, the tongue dorsum and supragingival dental plaque were collected from the oral cavity of each subject and subgingival dental plaque samples were collected from the patients with periodontitis; H. pylori infection was verified by polymerase chain reaction using primers that amplify the DNA sequence of a species-specific antigen present in all H. pylori strains; primers that amplify a region of urease gene, and primers for cagA and vacA (m1, m2, s1a, s1b, s2) genotyping. Results:, Thirty patients harbored H. pylori in the stomach, but it was not possible to detect H. pylori in any oral samples using P1/P2 and Urease A/B. The genotype cagA was also negative in all samples and vacA genotype could not be characterized (s-m-). Conclusion:, The oral cavity may not be a reservoir for H. pylori in patients with epigastric pain syndrome, the bacterium being detected exclusively in the stomach. [source] | |||||||||||||||||||||||||||||||||||||||||||