Showing papers on "Reagent published in 1991"

Oxidation of chlorobenzene with fenton's reagent

Abstract: The degradation of chlorobenzene and its oxidation products by hydroxyl radicals generated with Fenton's reagent was studied. In the absence of oxygen, chlorophenols, dichlorobiphenyls (DCBs), and phenolic polymers were the predominant initial products. In the presence of oxygen, DCB yields decreased markedly and chlorobenzoquinone was also formed. Chlorophenol isomers were further oxidized by OH's to form chlorinated and nonchlorinated diols. DCBs and the phenolic polymers were also oxidized. The highest yield of product formed per mole of H{sub 2}O{sub 2} consumed was observed in the pH range of 2-3. The pH dependence and product distributions suggest that complexes of aromatic intermediate compounds with iron and oxygen may play a role in regulating reaction pathways. At pH 3.0, approximately 5 mol of H{sub 2}O{sub 2}/mol of chlorobenzene were required to remove all of the aromatic intermediate compounds from solution.

Automated biological reaction apparatus

Abstract: An automated immunostaining apparatus having a reagent application zone and a reagent supply zone. The apparatus has a carousel slide support supporting a plurality of slide supports thereon, and drive means engaging the carousel slide support for consecutively positioning each of a plurality of slide supports in the reagent application zone. The apparatus also has a carousel reagent support having a plurality of reagent container supports thereon, and drive means engaging the carousel for rotating the carousel and positioning a preselected reagent container support in the reagent supply zone. The apparatus also has a reagent delivery actuator means positioned for engaging a reagent container positioned on a container support in the reagent delivery zone and initiating reagent delivery from the reagent container to a slide supported on a slide support in the reagent receiving zone.

Hydroxyl radical footprinting.

Abstract: Publisher Summary This chapter provides an overview on hydroxyl radical footprinting. Hydroxyl radical footprinting of DNA has evolved over the last several years into a facile and powerful technique for studying DNA structure and complexes of DNA with other molecules. The chapter describes the chemistry and history behind these techniques. In a footprinting experiment, a strand of DNA is subjected to cleavage by some reagent, both in the presence and absence of a DNA-binding ligand. Comparison of the cleavage patterns yields information on the structure of the DNA-ligand complex. Footprinting can also be used to obtain thermodynamic information on DNA-ligand complexes through footprint titration experiments.

Method for delivering an involatile reagent in vapor form to a CVD reactor

Abstract: A process and apparatus for delivering an involatile reagent in gaseous form, wherein an involatile reagent source liquid is flash vaporized on a vaporization matrix structure at elevated temperature. A carrier gas may be flowed past the flash vaporization matrix structure to yield a carrier gas mixture containing the flash vaporized source reagent. The matrix structure preferably has a high surface-to-volume ratio, and may suitably com GOVERNMENT RIGHTS IN INVENTION This invention was made with Government support under Contract No. N00014 88-0531 awarded by the Defense Advanced Projects Research Administration (DARPA). The Government has certain rights in this invention.

Surface-chemistry of colloidal silver in aqueous-solution - observations on chemisorption and reactivity

Abstract: Colloidal silver particles (3-nm diameter) are oxidized in the absence of air by organic and inorganic electron acceptors (such as nitrobenzene, methylviologen, nitropyridine oxide, and hexacyanoferrateIII) when nucleophilic reagents (such as CN- and SH-) are present in the solution. The mechanism of catalyzed metal oxidation proposed previously,2 according to which the interaction of surface atoms with the nucleophiles leads to an excess negative charge in the metal interior which can be picked up by the electron acceptors, explains the observed phenomena. This mechanism contains reversible steps. An experiment is reported in which the reverse sequence of events is observed: chemisorption of Ag(CN)2- on silver particles, producing an excess positive charge inside the particles, followed by complete reduction of the Ag+ ions of the adsorbed complexes by excess electrons that are deposited by a reducing reagent (i.e., organic radicals generated radiolytically). Ag(CN)2- ions in solution are not reduced by radicals. © 1991 American Chemical Society.

Activation to the transition state : reactant and solvent energy flow for a model sn2 reaction in water

Abstract: We have performed molecular dynamics calculations on a model Cl − +CH 3 ClS N 2 reaction in water in order to elucidate how the reactants obtain sufficient energy from the solvent to climb the potential energy barrier to reaction. This system, consisting of ionic and dipolar reagents in a polar solvent, is representative of a large class of chemical reactions with strong Coulombic reagent-solvent coupling. We find that the change in internal energy of the reactants during the barrier-climbing process involves three distinct epochs: (i) vibrational activation of the methyl chloride in the initial Cl − CH 3 Cl ion-dipole complex, (ii) gradual increase in kinetic and potential energies of the reactants, and (iii) fast dumping of reactant kinetic energy into reactant potential energy resulting in the reactants reaching the top of the potential energy barrier, with the symmetric structure Clδ − CH 3 δ + Clδ −

Calcium carbonate crystallization, agglomeration and form during continuous precipitation from solution

Abstract: Experiments were carried out to study the precipitation of calcium carbonate resulting from the mixing of aqueous solutions of calcium nitrate and sodium carbonate in a continuous-flow crystallizer at 25 degrees C in the pH range 8.5 to 10.5, reagent concentration 0.025 to 0.2 mol/l and solution residence times of 5 to 20 min. The population balance model is used to estimate nucleation, growth and agglomeration rates. Under the conditions studied, agglomeration of individual, previously formed crystals largely determines particle size and at higher reagent concentrations results in a bimodal distribution. The crystal form depends on the concentration of reagents, pH and residence time.

Blood sampler and component tester with guide member

Abstract: A reagent strip (10) and lance (6) are integrated to form a blood sampler and component tester (2). The reagent strip (10) is adapted for application against the skin of a patient and carries a reagent that indicates the concentration of a blood component in a blood sample placed in contact therewith. The lance (6), which is used to pierce the skin of a patient, is coupled to the reagent strip (10) through a resilient dome (4) which translates the lance between an extended position (where the lance through a guide member (20) extends beyond the reagent strip to puncture the skin of a patient) and a retracted position.

Modified peptide derivatives conjugated at 2-hydroxyethylamine moieties

Abstract: A process is disclosed for site-directed chemical modification of peptides and proteins that consists of two steps; (a) selective oxidation of a 2-hydroxyethylamine moiety, --CH(NH 2 )--CH(OH)--, in the peptide or protein to generate an aidehyde, and (b) reaction of the new aldehyde with a second reagent to form a product in which the native biological properties of the peptide are augmented by new and useful properties conferred by the second reagent. Additionally, the invention pertains to certain specified types of product formed by the above process.

Chemical deposition methods using supercritical fluid solutions

Abstract: A method for depositing a film of a desired material on a substrate comprises dissolving at least one reagent in a supercritical fluid comprising at least one solvent. Either the reagent is capable of reacting with or is a precursor of a compound capable of reacting with the solvent to form the desired product, or at least one additional reagent is included in the supercritical solution and is capable of reacting with or is a precursor of a compound capable of reacting with the first reagent or with a compound derived from the first reagent to form the desired material. The supercritical solution is expanded to produce a vapor or aerosol and a chemical reaction is induced in the vapor or aerosol so that a film of the desired material resulting from the chemical reaction is deposited on the substrate surface. In an alternate embodiment, the supercritical solution containing at least one reagent is expanded to produce a vapor or aerosol which is then mixed with a gas containing at least one additional reagent. A chemical reaction is induced in the resulting mixture so that a film of the desired material is deposited.

FT-IR Spectroscopy Study of the Ester Crosslinking Mechanism of Cotton Cellulose

Abstract: Polycarboxylic acids are being developed as new nonformaldehyde crosslinking agents for cotton fabrics to replace the traditional N-methylol reagents. In this research, the mechanism of esterification between polycarboxylic acids and cotton cellulose was elucidated using FT-IR spectroscopy. All the infrared spectroscopic data support the hypothesis that cyclic anhydrides are formed as intermediates, which in turn esterify with cotton cellulose. The infrared spectroscopic data also demonstrate that cyclic anhydrides are very reactive and are able to esterify with cotton cellulose without a catalyst present and at a temperature much lower than the curing temperatures used for polycarboxylic acids. Therefore, the chief role of catalysts such as sodium hypo phosphite is that they accelerate the formation of a cyclic anhydride from a polycar boxylic acid.

Self-contained assay assembly and apparatus

Abstract: A self-contained assembly (22) for assaying an analyte in a liquid sample. The pair of disc-like rotatable plates (24, 28) forming the assembly are relatively rotatable to align reagent reservoirs (92, 94, 96, 98) in one plate (28) with a reaction well (66) in the other plate (24), for sequential addition of multiple reagents, either in liquid or solid form, to the reaction well (66). In one embodiment, the reaction well (66) includes solid-phase particles which can be transferred from the reaction well (66) to spaced wells (74a, 74b, 74c) in the assembly by a combination of relative movement of the plate (28), and rotation of the entire assembly (22).

Ruthenium-catalyzed synthesis of symmetrical N,N'-dialkylureas directly from carbon dioxide and amines

Abstract: Aliphatic and araliphatic primary amines react with carbon dioxide at 120-140°C in the presence of ruthenium complexes and terminal alkynes, especially propargyl alcohols, to directly afford N,N'-disubstituted symmetrical ureas. The alkyne ruthenium intermediate acts as a dehydrating reagent. This new and mild method avoids the classical use of carbonyl precursors like phosgene or isocyanates

Production of methylguanidine from creatinine via creatol by active oxygen species: analyses of the catabolism in vitro.

Abstract: The chemical oxidative conversion of creatinine (Cr) into methylguanidine (MG) has been followed by 1H-NMR and HPLC. By using active oxygen species generated by Fenton's reagent (Fe2+ and H2O2) or the similar reagent (Fe3+ and H2O2), creatol (CTL), a metabolite newly isolated from the urine of uremic patients, and creatones A and B were experimentally detected in the reaction mixture and implicated as successive intermediates in the pathway from CR to MG. An alternative oxidation of Cr to demethylcreatinine (glycocyamidine) was also observed. The importance of CTL in this in vitro oxidation mechanism is discussed.

Doped sol-gel glasses for obtaining chemical interactions

Abstract: A method is proposed of obtaining a chemical interaction between at least one reagent trapped in sol-gel glass by doping it with the reagent, and diffusible solutes or components in an adjacent liquid or gas phase. The reagents, the solutes or the components can be any organic or inorganic compounds or materials of biological origin including enzymes. The doped sol-gel glass in various forms may be useful as analytical test, chromatographic medium, sensor, catalyst or biocatalyst, electrode or enzyme electrode, or other detection device.

Synthesis of monomeric and oligomeric bis(acetylide) complexes of platinum and rhodium

Abstract: Treatment of the complexes trans-[M(PBu3)2Cl2](M = Ni, Pd or Pt) with one equivalent of the reagent Me3SnCC–R–CCSnMe3(R =p-C6H4) affords the polymeric species trans-[–M(PBu3)2-CC–R–CC–]n, where as if two equivalents of the tin reagent are used in this reaction, when M = Pt, the complex trans-[Me3SnCC–R–CC–Pt(PBu3)2-CC–R–CCSnMe3] may be isolated, a precursor for further syntheses; the complex mer-trans-[Rh(PMe3)3(SnMe3)(CCPh)2] has been prepared by the addition of Me3SnCCPh to [Rh(PMe3)4][Cl], and this latter species, when treated with Me3SnCC–R′–CCSnMe3(R′=p-C6H4–C6H4–p), affords the oligomeric compound mer-trans-[–Rh(PMe3)3(SnMe3)–CC–R′–CC–]n.

Heat and air flow control for assay carrier

Abstract: A carousel for carrying and positioning a plurality of assays and a plurality of reagent packs in an immunoassay testing apparatus is designed to direct warmed or heated air in a predetermined and controlled manner for maintaining the assays and reagent packs within a specified, controlled temperature range.