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Silver Nitrate (silver + nitrate)
Terms modified by Silver Nitrate Selected AbstractsOptical properties of 2-aminopyridinium nitrato silverCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2010K. P. Bhuvana Abstract Crystals of 2-aminopyridinium nitrato silver have been synthesized by slow evaporation method. Grown crystals have been subjected to FTIR, Single crystal X-Ray diffraction and UV-Visible studies in order to investigate the structural and optical properties of the crystal. The FTIR spectrum reveals the presence of the functional group that corresponds to both 2-aminopyridine and silver nitrate, suggesting the formation of the compound, 2-aminopyridinium nitrato silver. From XRD it is observed that the crystal crystallizes in the structure of monoclinic with the space group of P21/c. The optical transmittance spectrum shows the maximum transparency of about 95% in the visible region is in consistent with the wide band gap, estimated as 4.738 eV. The optical constants n and k has also been determined from the transmittance data. The static dielectric constant is found to be 0.851. The wide band gap and the less dielectric constant suggest the suitability of this compound material for photoconductive applications. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Iodide-Selective Electrode Based on Copper PhthalocyanineELECTROANALYSIS, Issue 23 2002Saeed Shahrokhian Abstract Copper phthalocyanine was used as ion carrier for preparing polymeric membrane selective sensor for detection of iodide. The electrode was prepared by incorporating the ionophore into plasticized poly(vinyl chloride) (PVC) membrane, coated on the surface of graphite electrode. This novel electrode shows high selectivity for iodide with respect to many common inorganic and organic anions. The effects of membrane composition, pH and the influence of lipophilic cationic and anionic additives and also nature of plasticizer on the response characteristics of the electrode were investigated. A calibration plot with near-Nernestian slope for iodide was observed over a wide linear range of five decades of concentration (5×10,6,1×10,1,M). The electrode has a fast response time, and micro-molar detection limit (ca. 1×10,6,M iodide) and could be used over a wide pH range of 3.0,8.0. Application of the electrode to the potentiometric titration of iodide ion with silver nitrate is reported. This sensor is used for determination of the minute amounts of iodide in lake water samples. [source] Size- and Shape-Controlled Synthesis and Assembly of a Silver Nanocomplex in UV-Irradiated TSA SolutionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2006Liangbao Yang Abstract In this paper we describe the size-controlled synthesis ofa silver nanocomplex based on the reduction of silvernitrate (AgNO3) by UV-irradiated tungstosilicate acid [H4(SiW12O40), TSA] solution. This method allows the synthesis of ellipsoidal particles with an average size that is tunable between 2.4 and 84 nm by varying the molar ratio of silver nitrate to TSA, the pH of the reaction solution, and the reaction temperature. Silver nanorods can be formed from the ellipsoidal nanoparticles by controlling the aging time. The formation mechanism of these nanorods is also discussed. The nanoparticles are characterized by UV/Vis spectroscopy, FTIR spectroscopy, XRD analysis, XPS, electron diffraction (ED), TEM, and with a Zetasizer instrument. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Highly Surface-roughened "Flower-like" Silver Nanoparticles for Extremely Sensitive Substrates of Surface-enhanced Raman ScatteringADVANCED MATERIALS, Issue 45 2009Hongyan Liang Abstract Surface-enhanced Raman scattering (SERS) is a new optical spectroscopic analysis technique with potential for highly sensitive detection of molecules. Recently, many efforts have been made to find SERS substrates with high sensitivity and reproducibility. In this Research News article, we provide a focused review on the synthesis of monodispersed silver particles with a novel, highly roughened, "flower-like" morphology by reducing silver nitrate with ascorbic acid in aqueous solutions. The nanometer-scale surface roughness of the particles can provide several hot spots on a single particle, which significantly increases SERS enhancement. The incident polarization-dependent SERS of individual particles is also studied. Although the different "hot spots" on a single particle can have a strong polarization dependency, the total Raman signals from an individual particle usually have no obvious polarization dependency. Moreover, these flower-like silver particles can be measured by SERS with high enhancement several times, which indicates the high stability of the hot spots. Hence, the flower-like silver particles here can serve as highly sensitive and reproducible SERS substrates. [source] Sealing capacity of a photochromatic flowable composite as protective base in nonvital dental bleachingINTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2006C. Llena Abstract Aim, To evaluate microleakage of a flowable composite used as a protective isolating base, applied with different adhesive systems. Methodology, Seventy root-filled teeth were divided into seven groups. A flowable composite base (Tetric Flow Chroma) was used with three adhesive techniques (Syntac, Excite, Excite DCS; in the three cases with and without acid etching) and in a control group without dentine conditioning or adhesive placement. A 30% hydrogen peroxide solution was applied for 24 h in the pulp chambers, followed by the placement of a dye (silver nitrate) for 4 h. Each tooth was sectioned longitudinally, and examined under 4× magnification to assess the tooth/restoration dye leakage following a four-degree scale. Percentage of dye penetration was registered. Statistical analysis was made through the Tukey and Mann,Whitney U -tests. Results, Maximum leakage (100% of specimens) was recorded in the control group without an adhesive system. In the groups subjected to acid etching, the percentage of leakage corresponded to Excite DSC (10%), followed by Syntac (20%) and Excite (30%). In the groups in which only an adhesive system was used, 50% of the teeth demonstrated dye leakage. Statistically significant differences in terms of leakage were observed between the control group and the experimental groups (P < 0.05). There were no significant differences among the experimental groups, but comparing the leakage percentages obtained between the groups in which the teeth were subjected to prior acid etching, and those in which no etching was carried out, observed differences were significant (P = 0.04). Conclusions, There were no significant differences between the adhesive systems in terms of leakage. Acid etching significantly reduced leakage. [source] Fabrication of Large-Area Silicon Nanowire p,n Junction Diode Arrays,ADVANCED MATERIALS, Issue 1 2004K. Q. Peng Large-area silicon nanowire p,n junction diode arrays (see Figure) have been fabricated by chemical etching of planar silicon p,n junction wafers in aqueous HF solution that contains appropriate amounts of silver nitrate near room temperature. The I,V characteristics have been measured using current-sensing atomic force microscopy, and nonlinear and rectifying electrical transport behavior has been observed. [source] Intrapopulational polymorphism of nucleolus organizer regions in Serrapinnus notomelas (Characidae, Cheirodontinae) from the Paraná RiverJOURNAL OF FISH BIOLOGY, Issue 5 2008A. P. Santi-Rampazzo Analysis of the nucleolus organizer regions by silver nitrate (AgNOR), fluorescent in situ hybridization (FISH) and C-banding of Serrapinnus notomelas from the Paraná River, PR, Brazil revealed intrapopulational polymorphisms that could be classified into six patterns (I,VI). Pattern I consisted of a single nucleolus organizer region (NOR) on chromosome pair 26 with at least one active homologue, indicating that it was a preferential NO. This NOR was also present in all the other patterns. In addition, seven other variable pairs appeared in patterns II,VI. These polymorphisms may indicate transpositions of rDNA genes, located on pair 26, to various sites in the genome. These transpositions may be due to transpose mechanisms or reinsertion into sites that have sequences homologous with the inserts. C-band analysis also reflected this variability and confirmed the various patterns described here. [source] Alteration of argyrophilic nucleolar organizer region associated (Ag-NOR) proteins in apoptosis-induced human salivary gland cells and human oral squamous carcinoma cellsJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 4 2001Yasuhiro Morimoto Abstract: The level of argyrophilic nucleolar organizer regions (AgNORs) and AgNOR-associated proteins (Ag-NOR proteins) varies with cell activity, including ribosomal biogenesis occurring in proliferating cells. Proteins associated with some AgNORs are detected by a specific silver staining. To investigate a possible relationship between apoptosis and the AgNORs or Ag-NOR proteins, we examined the changes of AgNORs and Ag-NOR proteins during apoptosis in a human salivary gland cell line, HSG cells, and a human oral squamous carcinoma cell line, SCC-25 cells. Apoptosis was induced by treatment of HSG and SCC-25 cells with okadaic acid. Proteins prepared from HSG and SCC-25 cells treated with varying concentrations of okadaic acid (OA) were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by transferring to transfer membranes and staining for Ag-NOR proteins by modified Western blot analysis. Four major bands (110 kDa, 43 kDa, 39kDa, and 37 kDa) were detected in the proteins obtained from the control cells. The level of the 110-kDa protein decreased in the proteins prepared from OA-induced apoptotic cells; however, the reaction intensity of the other three bands was changed in apoptotic cells. An additional band of an 80-kDa Ag-NOR protein appeared and increased in the apoptotic cells. Cellular fractionation of HSG cells and SCC-25 cells was done with or without apoptotic induction. An 80-kDa Ag-NOR protein was detected in the nuclear fraction prepared from the apoptotic cells, while the 110-kDa protein decreased in the nuclear fraction of these cells. The 110-kDa Ag-NOR protein may be nucleolin (C23) as deduced from its AgNOR staining features, including molecular weight. The 80-kDa protein may be the cleavage product of the 110-kDa protein. In the cell-free apoptotic system, in which intact nuclei of HSG cells were incubated with the cytosol fraction of apoptotic HSG and SCC-25 cells, the 80-kDa Ag-NOR protein was detected in nuclei incubated with the cytosol fraction of apoptotic cells, while the level of the 110-kDa protein decreased. The changes of Ag-NOR proteins in nuclei prepared from SCC-25 cells incubated with cytosol fractions prepared from HSG and SCC-25 cells were identical to those of the HSG cells. The alternation of AgNORs in apoptosis-induced HSG cells was also examined using double staining with Hoechst 33342 and silver nitrate. Hoechst staining revealed typical apoptotic nuclei, which exhibited highly fluorescent condensed chromatin in OA-treated HSG cells. Silver grains representing AgNORs were not detected in the cells undergoing apoptosis. The dual-imposition view confirmed that AgNORs, which are visible as dots in nucleoli in the control cells, disappeared from the apoptotic nuclei of HSG cells. Our results indicate that the 110-kDa nucleolar Ag-NOR protein is associated with apoptosis and is cleaved during apoptosis. [source] IPM/DOSS/water microemulsions as reactors for silver sulfadiazine nanocrystal synthesisJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2005Jerry Nesamony Abstract The first goal of this work was the preparation of a water-in-oil microemulsion from components generally regarded as safe for use in humans. Stable formulations without need of a co-surfactant were prepared from isopropyl myristate (IPM), dioctyl sodium sulfosuccinate (DOSS), and water. A ternary phase diagram was prepared for the IPM/DOSS/water system. The IPM/DOSS/water microemulsions were characterized by conductivity and dynamic laser light scattering (DLS). The results obtained from conductivity experiments indicate conductivity values of less than 1 ,S/cm and were consistent with the formation of w/o microemulsions. The DLS results showed that the emulsified water droplets had an average diameter range of 9.2 to 19.7 nm, depending on composition. Modulation of the droplet size is possible by varying the water to DOSS molar ratio and DOSS to IPM ratio. The second goal of this work was the preparation of silver sulfadiazine (AgSD) nanoparticles. It was hypothesized that two separate microemulsions containing dispersed aqueous droplets of either sodium sulfadiazine or silver nitrate would react when mixed. The DLS results are consistent with the successful formation of submicron AgSD crystals. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:1310,1320, 2005 [source] Site-specific deposition of Ag nanoparticles on ZnO nanorod arrays via galvanic reduction and their SERS applicationsJOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2010Wei Song Abstract A controllable heterostructure consisting of ZnO nanorod arrays with attached Ag nanoparticles at only one end has been synthesized via a facile and convenient galvanic reduction method. Scanning electron microscopic images of these nanostructures showed good selectivity of Ag deposition on the tip of ZnO nanorod arrays. The formation of these regular AgZnO heterogeneous nanorod arrays can be explained by a localization of the electrons at the ends of the ZnO nanorods after the electron transfer step. By tuning the reaction time and the concentration of silver nitrate, the density of Ag nanoparticles on the tip of ZnO nanorods can be well controlled. Owing to the introduction of Ag nanoparticles with different densities, the resulting AgZnO heterogeneous nanorod arrays have been proved to be a versatile substrate for surface-enhanced Raman scattering not only for common organic molecules but also for label-free protein detection. Copyright © 2009 John Wiley & Sons, Ltd. [source] Production of monodisperse silver colloids by reduction with hydrazine: the effect of chloride and aggregation on SER(R)S signal intensity,JOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2004U. Nickel Abstract SER(R)S spectra with high signal intensity of Nile Blue A sulfate and 1,1,-diethyl-2,2,-cyanine iodide present in low concentration (,0.05 µM) can be recorded by employing certain silver sols in the absence of any chloride and without highly aggregated particles. The sols have been prepared by reduction of silver nitrate with hydrazine hydrate in a special procedure at a carefully established pH. In the presence of chloride, the maximum SER(R)S signal observed for a ca. 0.5 µM solution of Nile Blue A is of similar magnitude employing either a silver sol according to Lee and Meisel or our sol C, which contains nearly exclusively single silver particles with diameters of about 50 nm. Without added chloride, however, only our sol produces SER(R)S spectra with similar intensity as with chloride. Because the influence of chloride and coagulation on the intensity of the SER(R)S-signal can be controlled by varying the additives to our silver sol, further experiments of this kind can help to elucidate how these two parameters influence the magnitude of the SERS enhancement. Copyright © 2004 John Wiley & Sons, Ltd. [source] A method of measuring oil consumption by labelling with radioactive bromineLUBRICATION SCIENCE, Issue 3 2000H. Zellbeck Abstract A method of determining the oil consumption rate of combustion engines is presented. It is based on labelling the individual oil fractions of engine oil with radioactive bromine isotope82 Br and on the quantitative absorption of radioactive bromine compounds in the exhaust gas in an aqueous solution of nitric acid and silver nitrate. The advantages of this method are that the oil that is consumed in the exhaust gas can be directly measured, without the fluctuating amounts of oil in the sump influencing the result, and the behaviour of the individual components of the oil in the consumption process can be determined. The test is quick, only twenty minutes being required to detect oil consumption at one operating point; and with a single labelling, the oil consumption at a great number of working engine points can be measured 82 Br has a short half-life of only 36 h, so that compliance with radiation protection measures is inexpensive and investigations can be carried out using a conventional testing device. As part of the research project, a study was made of the influence of different base oil types, with and without polymer additives, on consumption. Results showed that Noack evaporation loss correlated with oil consumption only with boiling fractions of exactly the same base oil, and not with different, in particular synthetic, base oils; that polymer additives (VI improvers) significantly reduced the rate of oil consumption; and that the polymer additive and the type of base oil both had more influence on oil consumption than viscosity. [source] p.Q223R leptin receptor polymorphism associated with obesity in Brazilian multiethnic subjectsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2006Stenio Fernando Pimentel Duarte Several genes play a major role in obese phenotypes, and studies suggest that genetic variations among individuals, as well as their lifestyles, may bring about different body compositions. Among these genes, LEP, which codifies leptin, and the LEPR gene encoding its receptor were extensively studied for variants that could explain the obese phenotype. The LEPR p.Q223R gene polymorphism was analyzed in a sample of obese and nonobese individuals from Brazil to evaluate the role of this polymorphism in the obese phenotype in the population. Two hundred obese patients (60 males, 140 females, body mass index (BMI) >30 kg/m2) were screened, together with 150 lean or normal healthy individuals (63 males, 87 females, BMI <24 kg/m2). Genomic DNA was extracted and amplified by polymerase chain reaction (PCR). PCR products were digested with the restriction of endonuclease MspI, and separated by electrophoresis through an 8% polyacrilamide gel stained with silver nitrate. There was a significant difference in LEPR p.Q223R polymorphism frequency when comparing obese and lean subjects, with an odds ratio of 1.92 and a 95% confidence interval of 1.15,3.22 (P = 0.013). There is a strong association of the LEPR p.Q223R gene polymorphism with obesity in Brazil. Am. J. Hum. Biol. 18:448,453, 2006. © 2006 Wiley-Liss, Inc. [source] Anisotropy in optical transmittance and molecular chain orientation of silver- dispersed uniaxially drawn polyimide filmsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7 2003Sho-ichi Matsuda Abstract The anisotropy in optical transmittance in the visible and near-infrared region observed for uniaxially drawn and silver-dispersed polyimide (PI) films was investigated. The films were prepared in a one-step operation that consists of thermal curing and simultaneous uniaxial drawing of poly(amic acid) (PAA) films dissolving 5.7,,,20 mol% of silver nitrate. The PAA was converted to PI by heating, and the PI chains were orientated along the drawing direction during curing. Silver nanoparticles were precipitated in the films when they were cured in air and under nitrogen. In particular, silver nanoparticles aggregated along drawing direction and spheroidal nanoparticles (size of longer axis: 10,25,nm, aspect ratio: ca. 1.5) were observed in the films cured in air, and distinct anisotropy in optical transmittance was observed. The maximum optical anisotropy was obtained with a specific holding time at the final curing temperature (320,°C). In addition, the anisotropy can be controlled by polymer chain orientation when films are cured with the optimal holding time. In optimized preparing conditions, anisotropies in transmittance larger than 500,:,1 were obtained at the wavelengths between 700 and 900,nm, and its optical properties were retained after annealing at 150,°C for 1,hr. The PI films thus obtained can be used as thermally stable thin-film polarizers. Copyright © 2003 John Wiley & Sons, Ltd. [source] Staining efficiency of specific proteins depends on the staining method: Wheat gluten proteinsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 9 2008Hetty C. van den Broeck Abstract To analyze gluten proteins involved in celiac disease (CD) by proteomic analysis, prolamins extracted from hexaploid wheat varieties were analyzed by SDS-PAGE and 2-DE. Differences between staining methods (CBB, silver nitrate, SYPRO Ruby, and CyDye) were analyzed in comparison to immunoblotting. Staining efficiency varied per protein across methods, and complete staining of all gluten proteins could not be achieved by one of these methods. Care should be taken in the selection of staining method especially if one wants to relate the results to data obtained by immunoblotting. [source] Low doses of silver nitrate induce pleurodesis with a limited systemic responseRESPIROLOGY, Issue 6 2009Evaldo MARCHI ABSTRACT Background and objective: Both talc and 0.5% silver nitrate have been shown to induce effective pleurodesis. However, acute adverse systemic inflammatory effects have been described with both agents. The aim of this study was to assess in rabbits the systemic effects associated with a new technique of pleurodesis using repeated low doses of 0.1% silver nitrate. Methods: Rabbits were injected intrapleurally through a chest tube with 0.1% silver nitrate at 0, 24 and 48 h. Other groups received a single injection of 0.5% silver nitrate or 400 mg/kg of talc. Blood samples were collected at 24, 48 and 72 h, and at 7 days, and cytological and biochemical measurements were performed. After 28 days, the presence of macroscopic pleural adhesions and microscopic pleural fibrosis in the pleural cavity were evaluated. Results: Both talc and 0.5% silver nitrate caused significant increases in blood neutrophils, serum LDH, IL-8, transforming growth factor-, and CRP in comparison with control at almost all time points, whereas sequential doses of 0.1% silver nitrate only increased LDH and CRP in the first 24 h and transforming growth factor-, at all time points. All groups showed efficient pleurodesis, with no differences in pleural adhesions or fibrosis. Conclusions: Sequential doses of 0.1% silver nitrate produced efficient pleurodesis in rabbits, with a low systemic inflammatory response in comparison with 400 mg/kg of talc or 0.5% silver nitrate. [source] Morphological and molecular analysis of bromeliad-inhabiting ciliates in EcuadorTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 2 2005MICAH SAUL DUNTHORN The microbial inhabitants of Neotropical forests are poorly known. According to Finlay (2002, Science, 296:1061,1063) the majority of taxa in tropical forests should be previously described elsewhere. Conversely, Foissner (1999, Protist, 150:363,368) points to examples of endemic protists, and states that while we can identify the common species there are few trained taxonomists to identify the rare ones in large sampling investigations. To test these hypotheses, I am following up on an initial study of Foissner et al. (2003, Europ. J. Protistol., 39:365,372) of the ciliates inhabiting waters in canopy, sub-canopy and terrestrial bromeliad tanks in two Ecuadorian forests. Using morphological (protargol, silver nitrate, and silver carbonate stains; scanning electron micrographs) and molecular methods (SSU and ITS sequencing) I will concentrate my investigations on the colpodid taxa found free-living in the bromeliad tanks in two Ecuadorian forests. If I find many new taxa, Finlay's hypothesis may not be applicable to atleast bromeliad-inhabiting ciliates. [source] Urotricha psenneri n. sp. and Amphileptus piger (Vuxanovici, 1962) n. comb., Two Planktonic Ciliates (Protozoa, Ciliophora) from an Oligotrophic Lake in AustriaTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2004BETTINA SONNTAG ABSTRACT Two euplanktonic ciliates, Urotricha psenneri n. sp. (Prostomatida) and Amphileptus piger (Vuxanovici, 1962) n. comb. (Pleurostomatida), were discovered in the surface plankton of the oligotrophic Lake Traunsee in Austria. Their morphology and infra-ciliature were studied in live cells as well as in specimens impregnated with protargol and silver nitrate. Urotricha psenneri is a small urotrichid, less than 50 ,m length and with a single caudal cilium. It is unique in having (i) a massive oral basket projecting as a conspicuous bulge with cylindrical microfibrillar annulus and (ii) a curved brosse row 1 in the broad, barren circumoral area. Amphileptus piger (Vuxanovici, 1962) is about 55 × 13 ,m in vivo, has two macronuclear nodules with a single micronucleus in between in the posterior body half, has a single contractile vacuole with a terminal excretory pore, and few, but thick and thus highly conspicuous extrusomes. The amphileptid ciliary pattern (spica) is difficult to recognise due to the widely spaced basal bodies. [source] Cathepsin protease activity modulates amyloid load in extracerebral amyloidosisTHE JOURNAL OF PATHOLOGY, Issue 4 2006C Röcken Abstract In cerebral amyloidoses, such as Alzheimer's disease, proteolytic processing of the precursor protein is a fundamental mechanism of the disease, since it generates the amyloid protein. However, the putative significance of proteases in extracerebral amyloidoses is less well defined. In this study, we investigated the biological significance of cathepsin (Cath) B, CathK, and CathL in the pathology and pathogenesis of extracerebral amyloidoses by using the murine model of reactive or secondary AA amyloidosis with three different cathepsin-deficient mouse strains. Extracerebral AA amyloid was induced by injecting amyloid-enhancing factor and silver nitrate into CathB,/,, CathK,/,, and CathL,/, mice. Wild-type mice served as a control. CathK,/, mice deposited over 90% more amyloid and CathL,/, mice 60% less amyloid than the control (p < 0.0001). The amyloid load in CathB,/, mice did not differ from that in wild-type mice. In vitro degradation experiments with recombinant human and murine serum amyloid A (SAA) 1.1 and CathK and CathL showed that CathL generates a large number of differently sized SAA cleavage products. One of these fragments spans the heparin/heparan sulphate binding site and the neutral cholesterol ester hydrolase activating region of SAA. CathK showed only endoproteolytic activity and did not generate any AA amyloid-like peptides. This study provides unequivocal evidence that proteases modulate amyloid load in extracerebral amyloidosis. CathL was identified as an amyloid-promoting and CathK as an amyloid-retarding cysteine protease. CathB may only modulate the primary structure of the amyloid peptide without affecting amyloid load. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Ethylene regulates lateral root formation and auxin transport in Arabidopsis thalianaTHE PLANT JOURNAL, Issue 2 2008Sangeeta Negi Summary Lateral root branching is a genetically defined and environmentally regulated process. Auxin is required for lateral root formation, and mutants that are altered in auxin synthesis, transport or signaling often have lateral root defects. Crosstalk between auxin and ethylene in root elongation has been demonstrated, but interactions between these hormones in the regulation of Arabidopsis lateral root formation are not well characterized. This study utilized Arabidopsis mutants altered in ethylene signaling and synthesis to explore the role of ethylene in lateral root formation. We find that enhanced ethylene synthesis or signaling, through the eto1-1 and ctr1-1 mutations, or through the application of 1-aminocyclopropane-1-carboxylic acid (ACC), negatively impacts lateral root formation, and is reversible by treatment with the ethylene antagonist, silver nitrate. In contrast, mutations that block ethylene responses, etr1-3 and ein2-5, enhance root formation and render it insensitive to the effect of ACC, even though these mutants have reduced root elongation at high ACC doses. ACC treatments or the eto1-1 mutation significantly enhance radiolabeled indole-3-acetic acid (IAA) transport in both the acropetal and the basipetal directions. ein2-5 and etr1-3 have less acropetal IAA transport, and transport is no longer regulated by ACC. DR5-GUS reporter expression is also altered by ACC treatment, which is consistent with transport differences. The aux1-7 mutant, which has a defect in an IAA influx protein, is insensitive to the ethylene inhibition of root formation. aux1-7 also has ACC-insensitive acropetal and basipetal IAA transport, as well as altered DR5-GUS expression, which is consistent with ethylene altering AUX1-mediated IAA uptake, and thereby blocking lateral root formation. [source] Polymeric (,2 -nitrato-,2O:O,)(,2 -nitrato-,2O:O)(,4 -pyridinium-4-thiolato-,4S:S:S:S)disilver(I)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2004Yu-Biao Chen The title compound, [Ag2(NO3)2(C5H5NS)]n, was obtained from the reaction of silver nitrate with bis(4-pyridyl) disufide (4-PDS) in a mixture of ethanol and water, which suggests that the disulfide bond of 4-PDS can be cleaved under mild conditions. The structure of the title compound is a two-dimensional infinite array in which the asymmetric unit contains two Ag atoms, a pyridinium-4-thiolate molecule and two nitrate groups. Each pyridinium-4-thiolate molecule acts as a ,4 bridge, linking four Ag atoms, with Ag,S bond distances of 2.4870,(19), 2.5791,(19), 2.5992,(19) and 2.848,(2),Å. The Ag,Ag distances lie in the range 2.889,(2),3.049,(1),Å. [source] Bedside Detection of Urine ,-Hydroxybutyrate in Diagnosing Metabolic AcidosisACADEMIC EMERGENCY MEDICINE, Issue 8 2008Silas W. Smith MD Abstract Objectives:, While critically important, the rapid identification of the etiology of metabolic acidosis (MA) may be labor-intensive and time-consuming. Alcoholic, starvation, and severe diabetic ketoacidosis (AKA, SKA, and DKA, respectively) may produce ,-hydroxybutyrate (BOHB) in marked excess of acetone (ACET) and acetoacetate (AcAc). Unfortunately, current urine dipstick technology poorly detects ACET and cannot measure BOHB. The inability to detect BOHB might delay therapy for ketoacidoses or provoke unnecessary evaluation or empiric treatment of other causes of MA, such as toxic alcohol poisoning. The authors tested the previous assertion that commonly available hydrogen peroxide (H2O2) would improve BOHB detection. The effectiveness of alkalinization and use of a silver nitrate (AgNO3) catalyst was also assessed. Methods:, Control and urine test specimens containing from 0.5 to 800 mmol/L ACET, AcAc, and BOHB were prepared. Urine specimens were oxidized with H2O2 (3%) 1:9 (H2O2:urine), alkalinized with potassium hydroxide (KOH; 10%), exposed to AgNO3 sticks, or altered with a combination of these methods in a random fashion. Three emergency physicians (EPs) blinded to the preparation technique evaluated urine dipsticks (Multistix, Bayer Corp.) placed in the specimens for "ketones." Results:, Multistix detected AcAc appropriately; ACET was detected only at high concentrations of ,600 mmol/L. Multistix failed to measure BOHB at all concentrations tested. H2O2 improved urinary BOHB detection, although not to clinically relevant levels (40 mmol/L). Alkalinization and AgNO3 sticks did not improve BOHB detection beyond this threshold. Conclusions:, Addition of H2O2 (3%), alkalinization, or AgNO3 sticks did not improve clinically meaningful urine BOHB detection. Clinicians should use direct methods to detect BOHB when suspected. [source] Silver Coated Platinum Core,Shell Nanostructures on Etched Si Nanowires: Atomic Layer Deposition (ALD) Processing and Application in SERSCHEMPHYSCHEM, Issue 9 2010Vladimir A. Sivakov Dr. Abstract A new method to prepare plasmonically active noble metal nanostructures on large surface area silicon nanowires (SiNWs) mediated by atomic layer deposition (ALD) technology has successfully been demonstrated for applications of surface-enhanced Raman spectroscopy (SERS)-based sensing. As host material for the plasmonically active nanostructures we use dense single-crystalline SiNWs with diameters of less than 100 nm as obtained by a wet chemical etching method based on silver nitrate and hydrofluoric acid solutions. The SERS active metal nanoparticles/islands are made from silver (Ag) shells as deposited by autometallography on the core nanoislands made from platinum (Pt) that can easily be deposited by ALD in the form of nanoislands covering the SiNW surfaces in a controlled way. The density of the plasmonically inactive Pt islands as well as the thickness of noble metal Ag shell are two key factors determining the magnitude of the SERS signal enhancement and sensitivity of detection. The optimized Ag coated Pt islands on SiNWs exhibit great potential for ultrasensitive molecular sensing in terms of high SERS signal enhancement ability, good stability and reproducibility. The plasmonic activity of the core-shell Pt//Ag system that will be experimentally realized in this paper as an example was demonstrated in numerical finite element simulations as well as experimentally in Raman measurements of SERS activity of a highly diluted model dye molecule. The morphology and structure of the core-shell Pt//Ag nanoparticles on SiNW surfaces were investigated by scanning- and transmission electron microscopy. Optimized core,shell nanoparticle geometries for maximum Raman signal enhancement is discussed essentially based on the finite element modeling. [source] Synthesis and characterization of novel chiral ionic liquids and investigation of their enantiomeric recognition propertiesCHIRALITY, Issue 2 2008David K. Bwambok Abstract We report the synthesis and characterization of amino acid ester based chiral ionic liquids, derived from L - and D -alanine tert butyl ester chloride. The synthesis was accomplished via an anion metathesis reaction between commercially available L - and D -alanine tert butyl ester chloride using a variety of counterions such as lithium bis (trifluoromethane) sulfonimide, silver nitrate, silver lactate, and silver tetrafluoroborate. Both enantiomeric forms were obtained as confirmed by bands of opposite sign in the circular dichroism spectra. The L - and D -alanine tert butyl ester bis (trifluoromethane) sulfonimide were obtained as liquids at room temperature and intriguingly exhibited the highest thermal stability (up to 263°C). In addition, the ionic liquids demonstrated enantiomeric recognition ability as evidenced by splitting of racemic Mosher's sodium salt signal using a liquid state 19F nuclear magnetic resonance (NMR) and fluorescence spectroscopy. The L - and D -alanine tert butyl ester chloride resulted in solid salts with nitrate, lactate, and tetrafluoroborate anions. This illustrates the previously observed tunability of ionic liquid synthesis, resulting in ionic liquids of varying properties as a function of varying the anion. Chirality, 2008. © 2007 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||