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Selected AbstractsCellular uptake and biological activity of peptide nucleic acids conjugated with peptides with and without cell-penetrating abilityJOURNAL OF PEPTIDE SCIENCE, Issue 1 2010Yvonne Turner Abstract A 12-mer peptide nucleic acid (PNA) directed against the nociceptin/orphanin FQ receptor mRNA was disulfide bridged with various peptides without and with cell-penetrating features. The cellular uptake and the antisense activity of these conjugates were assessed in parallel. Quantitation of the internalized PNA was performed by using an approach based on capillary electrophoresis with laser-induced fluorescence detection (CE-LIF). This approach enabled a selective assessment of the PNA moiety liberated from the conjugate in the reducing intracellular environment, thus avoiding bias of the results by surface adsorption. The biological activity of the conjugates was studied by an assay based on the downregulation of the nociceptin/orphanin FQ receptor in neonatal rat cardiomyocytes (CM). Comparable cellular uptake was found for all conjugates and for the naked PNA, irrespective of the cell-penetrating properties of the peptide components. All conjugates exhibited a comparable biological activity in the 100 nM range. The naked PNA also exhibited extensive antisense activity, which, however, proved about five times lower than that of the conjugates. The found results suggest cellular uptake and the bioactivity of PNA-peptide conjugates to be not primarily related to the cell-penetrating ability of their peptide components. Likewise from these results it can be inferred that the superior bioactivity of the PNA-peptide conjugates in comparison with that of naked PNA rely on as yet unknown factors rather than on higher membrane permeability. Several hints point to the resistance against cellular export and the aggregation propensity combined with the endocytosis rate to be candidates for such factors. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd. [source] Quantification of alkylresorcinols in human plasma by liquid chromatography/tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2010Alastair B. Ross Alkylresorcinols (AR) are of interest as biomarkers of wholegrain wheat and rye intake in epidemiological studies and are currently mainly measured by gas chromatography/mass spectrometry (GC/MS) after labour-intensive sample preparation including liquid-liquid extraction, solid-phase extraction (SPE) and chemical derivatization. This manuscript describes and validates an alternative approach based on normal-phase liquid chromatography/tandem mass spectrometry for the quantification of alkylresorcinols in human plasma. The method requires neither SPE nor chemical derivatization and has a shortened run time compared to GC/MS. Normal- and reversed-phase columns and various mobile phases were evaluated with and without previous SPE of the samples. Normal-phase chromatography allowed separation of AR from the interfering triacylglycerols, diacylglycerols and sterols and enabled detection of AR even without SPE of the samples. The described method has instrumental lower limits of detection in the 25,75 pg range, and lower limits of quantification in the 75,250 pg range. Pooled human plasma and 2H4 -nonadecylresorcinol (internal standard) was applied to calibrate the method in the 20,12,000,nM range. The overall method showed intra-batch precision of 8.6% and an averaged accuracy of 100.2%. Applications for diverse human plasma samples are presented and are compared with the results determined by GC/MS. Based on the presented data; this method requiring less sample preparation is suggested for further evaluation as an alternative to GC/MS for analysis of biomarkers of wholegrain wheat and rye intake in epidemiological studies. Copyright © 2010 John Wiley & Sons, Ltd. [source] Electrospray ionization from a gap with adjustable widthRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 21 2006Patrik Ek In this paper, we present a new concept for electrospray ionization mass spectrometry, where the sample is applied in a gap which is formed between the edges of two triangular-shaped tips. The size of the spray orifice can be changed by varying the gap width. The tips were fabricated from polyethylene terephthalate film with a thickness of 36,µm. To improve the wetting of the gap and sample confinement, the edges of the tips forming the gap were hydrophilized by means of silicon dioxide deposition. Electrospray was performed with gap widths between 1 and 36,µm and flow rates down to 75,nL/min. The gap width could be adjusted in situ during the mass spectrometry experiments and nozzle clogging could be managed by simply widening the gap. Using angiotensin I as analyte, the signal-to-noise ratio increased as the gap width was decreased, and a shift towards higher charge states was observed. The detection limit for angiotensin I was in the low nM range. Copyright © 2006 John Wiley & Sons, Ltd. [source] Determination of patterns of biologically relevant aldehydes in exhaled breath condensate of healthy subjects by liquid chromatography/atmospheric chemical ionization tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2003Roberta Andreoli A method for the simultaneous determination of several classes of aldehydes in exhaled breath condensate (EBC) was developed using liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry (LC/APCI-MS/MS). EBC is a biological matrix obtained by a relatively new, simple and noninvasive technique and provides an indirect assessment of pulmonary status. The measurement of aldehydes in EBC represents a biomarker of the effect of oxidative stress caused by smoke, disease, or strong oxidants like ozone. Malondialdehyde (MDA), acrolein, ,,, -unsaturated hydroxylated aldehydes [namely 4-hydroxyhexenal (4-HHE) and 4-hydroxynonenal (4-HNE)], and saturated aldehydes (n -hexanal, n -heptanal and n -nonanal) were measured in EBC after derivatization with 2,4-dinitrophenylhydrazine (DNPH). Atmospheric pressure chemical ionization of the analytes was obtained in positive-ion mode for MDA, and in negative-ion mode for acrolein, 4-HHE, 4-HNE, and saturated aldehydes. DNPH derivatives were separated on a C18 column using variable proportions of 20,mM aqueous acetic acid and methanol. Linearity was established over 4,5 orders of magnitude and limits of detection were in the 0.3,1.0 nM range. Intra-day and inter-day precision were in the 1.3,9.9% range for all the compounds. MDA, acrolein and n -alkanals were detectable in all EBC samples, whereas the highly reactive 4-HHE and 4-HNE were found in only a few samples. Statistically significant higher concentrations of MDA, acrolein and n -hexanal were found in EBC from smokers. Copyright © 2003 John Wiley & Sons, Ltd. [source] Equally potent inhibitors of cholesterol synthesis in human hepatocytes have distinguishable effects on different cytochrome P450 enzymesBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 9 2000L.H. Cohen Abstract Six 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (the present cholesterol-lowering drugs known as statins), lovastatin (L), simvastatin (S), pravastatin (P), fluvastatin (F), atorvastatin (A) and cerivastatin (C) are shown to be potent inhibitors of cholesterol synthesis in human hepatocytes, the target tissue for these drugs in man. All six inhibited in the nM range (IC50 values: 0.2,8.0 nM). As daily used cholesterol-lowering drugs they are likely coadministered with other drugs. While several cytochrome P450 (CYP) enzymes are involved in drug metabolism in the liver and thus play an important role in drug,drug interaction it was investigated which of these enzymes are influenced by the active forms of the six statins. These enzyme activities were studied in human liver microsomal preparations, and in simian and human hepatocytes in primary culture. The following CYP reactions were used: nifedipine aromatization (CYP3A4), testosterone 6,-hydroxylation (CYP3A4), tolbutamide methylhydroxylation (CYP2C9), S -mephenytoin 4-hydroxylation (CYP2C19), bufuralol 1,-hydroxylation (CYP2D6), aniline 4-hydroxylation (CYP2E1), coumarin 7-hydroxylation (CYP2A6) and 7-ethoxyresorufin O -dealkylation (CYP1A1/2). In the human liver microsomes the statins (concentrations up to 400 µM) did not influence the CYP1A1/2 activity and hardly the CYP2A6 and CYP2E1 activities. Except P, the other five statins were stronger inhibitors of the CYP2C19 activity with IC50 values around 200 µM and the same holds for the effect of A, C and F on the CYP2D6 activity. L and S were weaker inhibitors of the latter enzyme activity, whereas P did not influence both activities. About the same was observed for the statin effect on CYP2C9 activity, except that F was a strong inhibitor of this activity (IC50 value: 4 µM). Using the assay of testosterone 6,-hydroxylation the CYP3A4 activity was decreased by L, S and F with IC50 values of about 200 µM and a little more by C and A (IC50 around 100 µM). P had hardly an effect on this activity. To a somewhat less extent the same trend was seen when CYP3A4 activity was measured using nifedipine as substrate. The inhibitory effects observed in microsomes were verified in suspension culture of freshly isolated hepatocytes from Cynomolgus monkey (as a readily available model) and of human hepatocytes. In general the same trends were seen as in the human microsomes, except that in some cases the inhibition of the CYP activity was less, possibly by the induction of the particular CYP enzyme by incubation of the cells with a particular statin. F remained a strong inhibitor of CYP2C9 activity in human and monkey hepatocytes. A induced the CYP2C9 in monkey hepatocytes but was an inhibitor of the CYP2C9 in human hepatocytes. A, S, L and C were moderate inhibitors in both cellular systems of CYP3A4. P was not affecting any of the CYP activities in the three systems studied. It is concluded that different CYP enzymes interact with different statins and therefore differences in between these drugs are to be expected when drug,drug interaction is considered. Copyright © 2000 John Wiley & Sons, Ltd. [source] Discovery of Adamantyl Ethanone Derivatives as Potent 11,-Hydroxysteroid Dehydrogenase Type,1 (11,-HSD1) InhibitorsCHEMMEDCHEM, Issue 7 2010Xiangdong Su Dr. Abstract 11,-Hydroxysteroid dehydrogenases (11,-HSDs) are key enzymes regulating the pre-receptor metabolism of glucocorticoid hormones. The modulation of 11,-HSD type,1 activity with selective inhibitors has beneficial effects on various conditions including insulin resistance, dyslipidemia and obesity. Inhibition of tissue-specific glucocorticoid action by regulating 11,-HSD1 constitutes a promising treatment for metabolic and cardiovascular diseases. A series of novel adamantyl ethanone compounds was identified as potent inhibitors of human 11,-HSD1. The most active compounds identified (52, 62, 72, 92, 103 and 104) display potent inhibition of 11,-HSD1 with IC50 values in the 50,70,nM range. Compound 72 also proved to be metabolically stable when incubated with human liver microsomes. Furthermore, compound 72 showed very weak inhibitory activity for human cytochrome P450 enzymes and is therefore a candidate for in,vivo studies. Comparison of the publicly available X-ray crystal structures of human 11,-HSD1 led to docking studies of the potent compounds, revealing how these molecules may interact with the enzyme and cofactor. [source] Phototunable Azobenzene Cholesteric Liquid Crystals with 2000 nm RangeADVANCED FUNCTIONAL MATERIALS, Issue 21 2009Timothy J. White Abstract Phototuning of more than 2000,nm is demonstrated in an azobenzene-based cholesteric liquid crystal (azo-CLC) consisting of a high-helical-twisting-power, axially chiral bis(azo) molecule (QL76). Phototuning range and rate are compared as a function of chiral dopant concentration, light intensity, and thickness. CLCs composed of QL76 maintain the CLC phase regardless of intensity or duration of exposure. The time necessary for the complete restoration of the original spectral properties (position, bandwidth, baseline transmission, and reflectivity) of QL76-based CLC is dramatically reduced from days to a few minutes by polymer stabilization of the CLC helix. [source] Thermally Stable Nanocrystalline Mesoporous Gallium Oxide PhasesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2009Chinmay A. Deshmane Abstract Semicrystalline and fully crystalline mesoporous galliumoxide phases were synthesized in the presence of ionic and non-ionic structure directing agents via Evaporation-Induced Self-Assembly (EISA) and Self-Assembly Hydrothermal-Assisted (SAHA) methods respectively. EISA led to partially crystalline mesoporous gallium oxide phases displaying unimodal pore size distribution in the range of ca. 2,5 nm and surface areas as high as 300 m2/g. SAHA led to nanocrystalline mesoporous uniform micron-sized gallium oxide spheres (ca. 0.3,6.5 ,m) with narrow size distribution displaying cubic spinel type structure. These mesophases displayed surface areas as high as ca. 221 m2/g and unimodal pore size distribution in the 5,15 nm range. Textural properties such as surface areas and pore sizes were effectively fine-tuned by the nature and relative concentration of the structure directing agents. Due to their high surface areas, tunability of pore sizes and the nature of the wall structure, these gallium oxide mesophases could find potential applications as heterogeneous catalysts.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis, Characterisation and Optical Properties of Silica Nanoparticles Coated with Anthracene Fluorophore and Thiourea Hydrogen-Bonding SubunitsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 36 2008Pilar Calero Abstract Bifunctionalised hybrid silica nanoparticles have been synthesised and characterised, and their optical emission properties in the presence of certain anions in acetonitrile solutions have been studied. The alkoxysilane derivatives N -butyl- N, -[3-(trimethoxysilyl)propyl]thiourea (1), N -phenyl- N, -[3-(trimethoxysilyl)propyl]thiourea (2) and 3-[(anthracen-10-yl)methylthio]propyltriethoxysilane (3) were prepared and used to functionalise uncoated LUDOX silica nanoparticles with a mean diameter of 18,±,2 nm. The functionalisation of the nanoparticle surfaces was carried out by two different approaches. The first approach relies on the consecutive grafting of the two subunits. In this protocol, the nanoparticles were first functionalised with anthracene derivative 3 (solid NA), and then treated with the corresponding binding sites 1 or 2 to result in the NA-Pt3 and NA-Bt3 solids. The second approach deals with the simultaneous grafting of 1 or 2 and the signalling subunit 3 in different ratios. This method was used for the preparation of the NA1Pt1, NA1Bt1, NA1Pt3 and NA1Bt3 nanoparticles. The bifunctionalised silica nanoparticles were characterised by using standard techniques. Acetonitrile suspensions of NA nanoparticles (5 mg in 20 mL) showed anthracene bands centred at ca. 350, 370 and 390 nm. Upon excitation at 365 nm, a typical emission band with fine structure in the 390,450 nm range was observed. Similar absorption and emission spectra were found for the bifunctionalised nanoparticles. The work is completed with a prospective study of the fluorescence of the prepared nanoparticles in the presence of organic (acetate, benzoate) and inorganic (F,, Cl,, Br,, CN,, HSO4, and H2PO4,) anions. The apparent binding constants (adsorption constants) for the interaction of NA-Pt3 with anions in acetonitrile were determined by performing a Langmuir-type analysis of fluorescence titration data.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Influence of Treatment Conditions on the Chemical Oxidative Activity of H2SO4/H2O2 Mixtures for Modulating the Topography of Titanium,ADVANCED ENGINEERING MATERIALS, Issue 12 2009Fabio Variola Abstract Host-tissue integration of medical implants is governed by their surface properties. The capacity to rationally design the surface physico-chemical cues of implantable materials is thus a fundamental prerequisite to confer enhanced biocompatibility. Our previous work demonstrated that different cellular processes are elicited by the nanotexture generated on titanium (cpTi) and Ti6Al4V alloy by chemical oxidation with a H2SO4/H2O2 mixture. Here, we illustrate that by varying the etching parameters such as temperature, concentration, and treatment time, we can create a variety of surface features on titanium which are expected to impact its biological response. The modified submicron and nanotextured surfaces were characterized by scanning electron (SEM) and atomic force (AFM) microscopies. Contact angle measurements revealed the higher hydrophilicity of the modified surfaces compared to untreated samples and Fourier transform infrared spectroscopy (FT-IR) established that the etching generated a TiO2 layer with a thickness in the 40,60,nm range. [source] Defect-Related Optical Behavior in Surface Modified TiO2 NanostructuresADVANCED FUNCTIONAL MATERIALS, Issue 1 2005M. Prokes Abstract The surface modification of TiO2 nanostructures to incorporate nitrogen and form visible light absorbing titanium oxynitride centers is studied. Anatase TiO2 structures in the 5,20,nm range, formed by a wet chemical technique, were surface modified and the nitridation of the highly reactive TiO2 nanocolloid surface, as determined by X-ray photoelectron spectroscopy (XPS) studies, is achieved by a quick and simple treatment in alkyl ammonium compounds. The nitriding process was also simultaneously accompanied by metal seeding resulting in a metal coating layer on the TiO2 structures. The structure of the resultant titanium oxynitride nanostructures remains anatase. These freshly prepared samples exhibited a strong emission near 560,nm (2.21,eV), which red-shifted to 660,nm (1.88,eV) and dropped in intensity with aging in the atmosphere. This behavior was also evident in some of the combined nitrogen doped and metal seeded TiO2 nanocolloids. Electron spin resonance (ESR) performed on these samples identified a resonance at g,=,2.0035, which increased significantly with nitridation. The resonance is attributed to an oxygen hole center created near the surface of the nanocolloid, which correlates well with the observed optical activity. [source] Correlative 3D Microscopy: CLSM and FIB/SEM TomographyIMAGING & MICROSCOPY (ELECTRONIC), Issue 3 2008A Study of Cellular Entry of Vaccinia Virus Abstract Subcellular structural investigation on single cells or tissue samples requires the coupling of optimal structural preservation with detailed imaging at the light and electron microscopic level. To apply light microscopy (FLM, CLSM) and electron microscopy (SEM, FIB/SEM, TEM) imaging modes to the identical sample area has become available with the establishment of chemical preparation, or freeze-substitution protocols after high pressure freezing, adapted to retain fluorophores. One and the same structure can now be investigated at mm to nm range in 2D and 3D in a multimodal set-up [1, 2]. In combination with live cell imaging prior to immobilisation, this approach becomes a powerful tool in life science, e.g. in the development of new anti-viral strategies, as this requires detailed information on the replication cycle of viruses and their interaction with their host cells. [source] Fluorescence and coloration of grey hairINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2009S. Daly Synopsis Grey hair samples were collected from 11 individuals and separated into un-pigmented and pigmented fibres (International Hair Importers). Fluorescence measurements were obtained by using a double-grating fluorescence spectrophotometer and a bifurcated fibre optics accessory to measure the spectra directly from the surface of hair at various distances from the fibre root. Colour measurements were carried out by using a Hunter colorimeter. The fluorescence spectra of un-pigmented hair obtained by the excitation at 290 nm show a peak at 356 nm [tryptophan (Trp)], and multi-peak emissions in the range from 395 to 500 nm. A significant variation in the Trp emission intensity at 356 nm vs. the intensity of emission in the 395,500 nm range was observed for hair collected from various individuals with yellow coloured hair producing stronger relative emission in 395,500 nm range. Quantitative measurements of coloration and the calculation of the Yellowness Index (YI) showed linear correlation between YI and the ratio of fluorescence intensities I440/I356 The spectra obtained by excitation at 320 nm showed the emission peaks at 395 nm (unidentified), 420 nm (N -formylkynurenine), 460 nm (kynurenine), and 495 nm (3-hydroxykynurenine), which are the products of oxidative or metabolic conversion of tryptophan. Un-pigmented, yellow hair showed a build-up of the fluorescence band corresponding to 3-hydroxykynurenine at 495 nm. The data also showed the fluorescence quenching effect of melanin resulting in the lowering of the fluorescence intensity of pigmented hair. The spectra obtained at various positions along the fibres demonstrated gradual photo-decomposition of hair chromophores during their lifetimes. This was indicated by a decrease of Trp fluorescence intensity, which was relatively fast (8·10,4,1.5·10,3 [day,1] as calculated for hair obtained from various individuals) for un-pigmented hair and slower for pigmented hair. A decrease in Trp emission was accompanied by an increase in the yellow coloration toward the ends of un-pigmented fibres. Resume Des échantillons de cheveux gris ont été collectés chez onze personnes et triés entre fibres non pigmentés et fibres pigmentés (International Hair Importers). Les mesures de fluorescence ont été réalisées à l'aide d'un spectrophotomètre de fluorescence double grille et d'un accessoire constitué d'une fibre optique bifurquée. Ce dispositif permet la mesure du spectre directement depuis la surface d'un cheveu à diverses distances de sa racine. Les mesures de couleur ont été réalisées à l'aide d'un colorimètre HUNTER. Le spectre de fluorescence d'un cheveu non pigmenté obtenu par excitation à 290 nm montre un pic à 356 nm (tryptophane : Trp) et des émissions multi pics dans l'intervalle 395 à 500 nm. On observe une variation significative de l'intensité du Trp à 356 nm par rapport à l'intensité d'émission dans l'intervalle 395,500 nm sur les cheveux prélevés sur diverses personnes, les cheveux colorés en jaune produisant une émission relative plus forte dans l'intervalle 395,500 nm. Les mesures quantitatives de la couleur et le calcul de l'indice de jaunissement (YI) montrent une corrélation linéaire entre YI et le rapport des intensités de fluorescence I 440/I356. Le spectre obtenu par excitation à 320 nm montre des pics d'émission à 395 nm (non identifiés), 420 nm (N-formylkynurenine), 460 nm (kynurenine), 495 nm (3-hydroxy kinurenine) propres aux produits d'oxydation ou de conversion métabolique du Tryptophane. Les cheveux jaunes non pigmentés présentent une saturation de la bande de fluorescence correspondant à la 3-hydroxykynurenine à 495 nm. Ces données montrent également l'effet de quenching de la mélanine entraînant un affaiblissement de l'intensité de la fluorescence des cheveux pigmentés. Le spectre obtenu en divers endroits le long des fibres indique une photodécomposition graduelle des chromophores des cheveux durant leur temps de vie. Ceci se traduit par une diminution de l'intensité de fluorescence du Trp qui est relativement rapide pour les cheveux non pigmentés (8,10,4,1,5,10,3 [jour , 1], conformément aux calculs effectués sur des cheveux prélevés sur différents individus) et par une diminution plus lente pour les cheveux pigmentés. Une diminution de l'émission du Trp s'accompagne d'une augmentation de la coloration jaune de l'extrémité des cheveux, détectable sur des cheveux non pigmentés. [source] Developing beauty-enhancing makeup by controlling light reflected from skin (II) , a makeup foundation producing an optimal reflectance dip on skinINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2007Y. Sakazaki Spectral reflection curves of human skin generally show a characteristic dip in the 500,600 nm range. This ,dip' is unique for each person, and is believed to be caused by the spectral absorption of blood. We investigated the spectral reflectance of human skin and discovered a very interesting correlation between the area of the reflectance dip and L* value (lightness of the skin). The standard area of reflectance dip (Ads) is defined and calculated from the correlation we discovered. The actual area of reflectance dip (ADa) is calculated from the spectral reflection curve. The ratio of ADa and ADs was found to be a very useful optical parameter for skin complexion perception. By artificially creating different optical environments and varying ADa/ADs from 10 to 200%, we found that skin appeared more beautiful when ADa/ADs was in the 100,125% range. We therefore considered methods for applying these results into the development of cosmetic products. Investigation and testing of many different pigments resulted in the development of specially-designed powdered fiber with a #-shaped cross section dyed magenta. An experimental foundation with this powdered fiber produced a clear reflectance dip by raising reflectance in the short and long wavelength ranges. ADa/ADs increased from 49 to 107% without reducing lightness when this makeup foundation was applied on sallow skin. [source] "Click" Polymer-Supported Palladium Nanoparticles as Highly Efficient Catalysts for Olefin Hydrogenation and Suzuki Coupling Reactions under Ambient ConditionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2009Cátia Ornelas Abstract Complexation of palladium(II) acetate [Pd(OAc)2] or dipotassium tetrachloropalladate [K2PdCl4] to "click" polymers functionalized with phenyl, ferrocenyl and sodium sulfonate groups gave polymeric palladium(II)-triazolyl complexes that were reduced to "click" polymer-stabilized palladium nanoparticles (PdNPs). Transmission electron microscopy (TEM) showed that reduction using sodium borohydride (NaBH4) produced PdNPs in the 1,3,nm range of diameters depending on the nature of the functional group, whereas slow reduction using methanol yielded PdNPs in the 22,25,nm range. The most active of these PdNPs (0.01% mol Pd), stabilized by poly(ferrocenyltriazolylmethyl)styrene, catalyzed the hydrogenation of styrene at 25,°C and 1 atm hydrogen, with turnover numbers (TONs) of 200,000. When stabilized by the water-soluble poly(sodium sulfonate-triazolylmethyl)styrene, the PdNPs (0.01% mol Pd) catalyze the Suzuki,Miyaura coupling between iodobenzene (PhI) and phenylboronic acid [PhB(OH)2] in water/ethanol (H2O/EtOH) at 25,°C with TONs of 8,200. This high catalytic activity is comparable to that obtained with "click" dendrimer-stabilized PdNPs under ambient conditions. [source] Treatment of linear and spider telangiectasia with an intense pulsed light sourceJOURNAL OF COSMETIC DERMATOLOGY, Issue 4 2004R A Retamar Summary Background, The flashlamp-pumped pulsed dye laser (585 and 577 nm) has proved to be an effective and safe treatment option in the therapy of linear and spider facial telangiectasia. Nevertheless, the postoperative purpura, which most patients see as cosmetically disfiguring, has always been a matter of concern. Aims, To test the effectiveness and safety of an intense pulsed light source (IPLS), which emits non-coherent light adjustable within the 515,1200 nm range, in the treatment of linear and spider facial telangiectasia. Patients & Methods, One hundred and forty patients with linear and stellate facial telangiectasia were treated with an IPLS. Results, In 94 (67.1%) the results were considered excellent (clearance of 80,100%), 43 (30.7%) showed good results (clearance of 40,80%) and in 3 patients (2.1%) the results were poor (clearance < 40%). Post-treatment side effects were minimal and well tolerated. There were no instances of scarring or other permanent side effects. Owing to the large spot size, a large area could be treated within one session. No anaesthesia was required. Conclusion, IPLS is a highly effective and comparably safe therapeutic alternative to the pulsed dye laser in the treatment of facial telangiectasia. The rate of cosmetically relevant side effects is considerably smaller, patient compliance is excellent and the method can easily be applied in an outpatient setting. [source] Syntheses and photophysical properties of some 4-arylpyridinium saltsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2001Charles J. Kelley A number of 4-arylpyridines, many methoxy substituted, were prepared by an efficient two-step method involving aryl Grignard addition to 1-methyl-4-piperidone and direct aromatization of the resulting 4-aryl-4-piperidinols. The pyridines were N -alkylated to give sulfonate salts desired for their fluorescent properties. Study of selected compounds as laser dyes revealed several structures to be efficient dyes lasing in the 530-550 nm range. Two new diazaquaterphenyls were prepared and were quaternized. These salts exhibited intense fluorescence in the 420-450 nm range, but would not lase. A phenolic azaterphenyl suitably substituted for excited state intramolecular proton transfer (ESIPT) did not fluoresce at all. [source] Modifications and oxidation of lipids and proteins in human serum detected by thermochemiluminescenceLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 2 2003Sergei Shnizer Abstract Detection of electronically excited species (EES) in body fluids may constitute an important diagnostic tool in various pathologies. Examples of such products are triplet excited carbonyls (TEC), which can be a source for photon emission in the 400,550,nm range. The aim of the present study was to determine the actual contribution of lipid and protein components (protein carbonyls) to photon emission generated by thermochemiluminescence (TCL) during the heating of biological fluids. In this study, a new TCL Photometer device, designed by Lumitest Ltd, Israel, was used. Samples were heated to a constant temperature of 80,±,0.5°C for 280,s and photon emission was measured at several time points. In order to compare the results of TCL measurements to conventional methods of detecting lipid and protein oxidation, each examined sample was also heated in a waterbath at 80°C for 10,280,s. Lipid and protein oxidation were subsequently measured using conventional methods. The TCL of four polyunsaturated fatty acids (PUFA) with three to six double bonds was measured. The elevation of the PUFA TCL amplitude correlated with the increase in the number of double bonds of PUFA. A correlation between the increase in TCL intensity and protein carbonyl generation in bovine serum albumin (BSA) was also observed. In the venous blood serum, our study showed that an increase of TCL intensity during heating reflected the cleavage of TEC of lipid origin. Our study suggests that biological molecules such as proteins, lipids and other molecules, which may become unstable during heating, are capable of generating EES. We demonstrated that a TCL curve can be used as a kinetic model for measuring oxidative processes, which reflects modifications of different molecules involved in the oxidative stress phenomena. Copyright © 2003 John Wiley & Sons, Ltd. [source] Dendritic macromolecules at the interface of nanoscience and nanotechnologyMACROMOLECULAR SYMPOSIA, Issue 1 2003Jean M.J. Fréchet Abstract As a result of their unique architecture and structural as well as functional versatility, dendrimers have generated considerable interest in numerous areas of the physical sciences, engineering, as well as the biological sciences. Both their size - in the 1-10 nm range - and their globular shape resemble those of many proteins suggesting a host of biomimetic and nanotechnological applications. This brief highlight describes some of our recent work with nascent applications of dendrimers as unimolecular nanoreactors, as nanoscale antennae for energy harvesting and transduction, and as nanosized carriers for diagnostic or therapeutic applications. While implementation of some of these applications may still be distant, the impatient critic might remember that new markets are not created overnight as demonstrated by the slow commercial acceptance of many promising molecules and technologies with development frequently extending decades after their initial discovery. [source] Annealing crystallization of a-Ge/Al/Si and a-Ge/Si thin filmsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2005F. Fajardo Abstract This work describes the temperature-induced crystallization of amorphous Ge (a-Ge) as a function of the thickness of the a-Ge films (in the 12,2600 nm range), which were deposited both onto c-Si substrates and c-Si substrates covered with aluminium. After deposition, the samples were submitted to cumulative thermal annealing treatments. It is shown that the temperature of crystallization depends on the thickness of the a-Ge films and to the presence (or not) of the Al layer. For an annealing temperature (Ta) of ,700 °C, for example, the Raman spectra of films thinner than ,1000 nm and deposited onto c-Si substrates are completely dominated by the sharp phonon mode of crystalline Si. Films with thicknesses equal to 300, 1000 and 2600 nm, deposited onto Al/c-Si, and treated at Ta = 600 °C, on the other hand, clearly display two additional peaks at 405 and 490 cm,1. They correspond to the Raman modes of Si,Ge and Si,Si modes, suggesting the formation of a SiGe alloy during the thermal anneal of the films. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical properties of sub-100 nm diameter nanoposts with embedded InGaN quantum well heterostructuresPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2005Yiping He Abstract Dense arrays of deeply etched InGaN/GaN multiple quantum-well (MQW) nanoposts with diameters in the 40-100 nm range have been fabricated, to investigate their optical emission in the deep-subwavelength size regime. Robust violet/blue light luminescence at high yield has been spectroscopically analyzed. The emission from linear nanoscale arrays is strongly polarized. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spectroscopic investigation of Nd3+ in ASLPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2005A. Lupei Abstract Nd3+ -activated strontium lanthanum aluminate Sr1,xNdyLax,yMgxAl12,xO19 (ASL: Nd) crystals are investigated especially for 4F3/2,4I9/2 laser emission in 900 nm range. The optimisation of laser emission characteristics requires a detailed knowledge of spectral features and their dependence on composition. The spectral investigation of Nd3+ in ASL on an extended composition range (especially small x) reveals new spectral features. Connecting spectral and structural data, the role of charge compensator Mg2+ ion in the structure of the two main Nd3+ structural centers in ASL, C1 and C2, is proposed. It is inferred that these results enable a rigorous selection of the optimal composition for improving laser properties. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Conducting nanocomposites of polyacrylamide with acetylene black and polyanilinePOLYMER COMPOSITES, Issue 4 2009Pramod Kumar Verma A conducting nanocomposite of polyacrylamide (PAA) with acetylene black was prepared via Na2AsO3 -K2CrO4 redox initiated polymerization of acrylamide in water containing a suspension of acetylene black. FTIR analyses confirmed the presence of PAA in the nanocomposites. The composite possessed lower thermal stability than AB and exhibited three stages of decomposition upto 430°C. DSC thermogram revealed three endotherms due to minor thermal degradation (at ,100°C), melting and decomposition (at ,230°C) and major decomposition (at ,430°C). TEM analyses indicated the formation of globular composite particles with sizes in 30,70 nm range. In contrast to the very low conductivity of the base polymer the composite showed a dramatic increase in conductivity (0.19,6.0 S/cm) depending upon AB loading. Log (conductivity) ,1/T plot showed a change in slope at ,127°C indicating the manifestation of an intrinsic conductivity region and an impurity conductivity region. The activation energy for conduction as estimated from the slope of region I was 0.008 eV/mol. The C,V plot was linear showing a metallic behavior. For comparison in conductivity PAA-polyaniline composite was also prepared which however displayed much lower conductivity values. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] Diffractive imaging for periodic samples: retrieving one-dimensional concentration profiles across microfluidic channelsACTA CRYSTALLOGRAPHICA SECTION A, Issue 4 2007Oliver Bunk A technique has been developed that allows determination of the concentration profiles of colloidal solutions or any kind of fluid under confinement. Currently, submicrometre-wide channels are sampled with a resolution in the 10,nm range. The method comprises regular arrays of microfluidic channels and one-dimensional X-ray phase-retrieval techniques for the analysis of small-angle X-ray diffraction from the array structures. Recording the X-ray diffraction data requires a low dose on each individual channel since the sum of the signals from all channels is detected. The determined concentration profiles represent the ensemble average rather than individual entities and are obtained in a model-independent way. As an example, amplitude and phase of the exit field and concentration profiles for a colloidal fluid within confining channels of different widths are shown. [source] A biomimetic tubular scaffold with spatially designed nanofibers of protein/PDS® bio-blends,BIOTECHNOLOGY & BIOENGINEERING, Issue 5 2009Vinoy Thomas Abstract Electrospun tubular conduit (4,mm inner diameter) based on blends of polydioxanone (PDS II®) and proteins such as gelatin and elastin having a spatially designed trilayer structure was prepared for arterial scaffolds. SEM analysis of scaffolds showed random nanofibrous morphology and well-interconnected pore network. Due to protein blending, the fiber diameter was reduced from 800,950,nm range to 300,500,nm range. Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) results confirmed the blended composition and crystallinity of fibers. Pure PDS scaffold under hydrated state exhibited a tensile strength of 5.61,±,0.42,MPa and a modulus of 17.11,±,1.13,MPa with a failure strain of 216.7,±,13%. The blending of PDS with elastin and gelatin has decreased the tensile properties. A trilayer tubular scaffold was fabricated by sequential electrospinning of blends of elastin/gelatin, PDS/elastin/gelatin, and PDS/gelatin (EG/PEG/PG) to mimic the complex matrix structure of native arteries. Under hydrated state, the trilayer conduit exhibited tensile properties (tensile strength of 1.77,±,0.2,MPa and elastic modulus of 5.74,±,3,MPa with a failure strain of 75.08,±,10%) comparable to those of native arteries. In vitro degradation studies for up to 30 days showed about 40% mass loss and increase in crystallinity due to the removal of proteins and "cleavage-induced crystallization" of PDS. Biotechnol. Bioeng. 2009; 104: 1025,1033. © 2009 Wiley Periodicals, Inc. [source] CCR3-active chemokines influence eosinophil adhesion to endothelial cells under static and flow conditionsCLINICAL & EXPERIMENTAL ALLERGY REVIEWS, Issue 1 2007H. Tachimoto Summary We recently demonstrated that CCR3-active chemokines promote rapid detachment of eosinophils bound to vascular cell adhesion molecule-1 (VCAM-1) in vitro. Eosinophils adhered well to immobilized human recombinant VCAM-1 primarily via ,4,1 integrin. Eotaxin-2, a CCR3-specific chemokine, induced eosinophil de-adhesion from VCAM-1. In contrast, very few eosinophils spontaneously adhered to bovine serum albumin (BSA), and eosinophil adhesion to BSA was enhanced by eotaxin-2 over a similar nm range of concentrations. This enhancement of BSA adhesion was dependent on ,2 integrins. Eosinophil ,4,1 integrins can mediate rolling on VCAM-1 under physiological flow conditions. Although we observed a reduction of eosinophil accumulation on immobilized VCAM-1 in response to eotaxin-2 under physiological flow conditions, this reduction of adhesion was not observed when VCAM-1 and intercellular adhesion molecule-1 (ICAM-1) were co-immobilized. Based on antibody-blocking studies, this appears to be caused by a chemokine-induced shift in integrin usage away from ,1 integrin-dominated interactions with VCAM-1 towards ,2 integrin-dominated interactions with ICAM-1. Our results confirm the important role of integrins and chemokines in selective eosinophil migration processes. CCR3-active chemokines may be necessary to facilitate de-adhesion from luminal VCAM-1 and to facilitate the process of diapedesis by shifting integrin usage in eosinophils away from ,1 integrin-dominated interactions with VCAM-1 towards ,2 integrin-dominated interactions with ICAM-1. The critical importance of integrins and chemokines in eosinophilic inflammation lends support for targeting these molecules with novel therapeutic agents. [source] | |||||||||||||||||||