Showing papers on "Reagent published in 1995"
TL;DR: The Holy Grail of C-H activation research is not to find new CH activation reactions but to obtain an understanding of them that will allow the development of reagents capable of selective transformations of C -H bonds into more reactive functionalized molecules as discussed by the authors.
Abstract: One {open_quotes}Holy Grail{close_quotes} of C-H activation research, therefore, is not simply to find new C-H activation reactions but to obtain an understanding of them that will allow the development of reagents capable of selective transformations of C-H bonds into more reactive functionalized molecules. Although a few interesting organic and main group reagents have been discovered that show intriguing potential for meeting this goal, much of the activity in this field has been in transition metal chemistry. The present Account therefore reflects this emphasis. 109 refs., 3 figs.
1,234 citations
TL;DR: The use of 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane as a reagent in quantitative 31P NMR analysis of the hydroxyl groups in lignins has been thoroughly examined, and an experimental protocol recommended for spectra acquisition has been developed as discussed by the authors.
Abstract: The use of 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane as a phosphitylation reagent in quantitative 31P NMR analysis of the hydroxyl groups in lignins has been thoroughly examined, and an experimental protocol recommended for spectra acquisition has been developed. Quantitative analysis of six “standard lignins” gave results comparable to those obtained by other methods of analysis. Excellent resolution of the various phenolic hydroxyl environments including those present in condensed moieties was observed. However, this was at the expense of resolution in the aliphatic hydroxyl region, where no distinction between primary, secondary, and the erythro and threo forms of the secondary hydroxyls of the ,l?-0-4 bonds can be made.
747 citations
Journal Article•
TL;DR: The modified precipitation does not prolong or increase the complexity of the TRI Reagent procedure and was tested by isolation of RNA from polysaccharide- and proteoglycan-rich tissues such as rat liver and aorta.
Abstract: A modification of the TRI Reagent procedure has been elaborated for isolation of RNA from polysaccharide- and proteoglycan-rich material. In the modified procedure, RNA is precipitated from the aqueous phase by the combined action of isopropanol and a high-salt concentration. Under these conditions, RNA is effectively precipitated while contaminating polysaccharides and proteoglycans remain in the soluble form. The modified precipitation does not prolong or increase the complexity of the TRI Reagent procedure. The new procedure was tested by isolation of RNA from polysaccharide- and proteoglycan-rich tissues such as rat liver and aorta.
620 citations
329 citations
308 citations
TL;DR: In this article, the reaction of azodye active yellow lightfast 2 KT (AYL) with H2O2/Fe2+ system (Fenton's reagent) causes a drop in colourization by 95-97% at the minimum dosage of 17 mg·l−1 H 2O2.
237 citations
224 citations
TL;DR: In this article, the azasteroid 5α-reductase inhibitor MK-0434 is described for the direct conversion of a highly hindered ester to a ketone, and the reaction of an ester with N, O -dimethylhydroxylamine and a suitable organomagnesium reagent or lithium amide base is described.
198 citations
TL;DR: This review discusses in detail enzyme structure, biocatalysis, enzymes as analytical reagents, properties of glucose oxidase (including a historical account), and the use of glucose oxidation as an analytical reagent in homogeneous systems as well as an immobilized reagent.
Abstract: Glucose oxidase (EC 1.1.3.4) is the most widly employed enzyme as analytical reagent. This is the result of (1) its utility in the determination of glucose, an analyte of wide analytical interest, and (2) its relatively low cost and good stability that make the glucose/glucose oxidase system a very convenient model for method development (particularly in the area of biosensors). This review discusses in detail enzyme structure, biocatalysis, enzymes as analytical reagents, properties of glucose oxidase (including a historical account), and the use of glucose oxidase as an analytical reagent in homogeneous systems as well as an immobilized reagent.
186 citations
Patent•
29 Sep 1995
TL;DR: In this paper, an analytical device for determining the presence or amount of an analyte in a test sample is presented. But the analytical device is not suitable for the detection of the analyte.
Abstract: The present invention relates to analytical devices for determining the presence or amount of an analyte in a test sample. The analytical devices comprise an inlet port, a vent, a channel, and an array of structures. The structures have immobilized reagent covalently or non-covalently attached to the surface of the structures. The immobilized reagent captures analyte in the test sample where it is detected by a detection system. The present invention also provides methods and reagents for performing assays utilizing the analytical devices of the present invention. The present invention also provides methods of manufacturing the analytical devices of the present invention.
175 citations
TL;DR: In this article, the catalytic performance of aluminum-free ZSM-5 (TS-1) was investigated for the selective oxidation of alkanes and alkenes using aqueous H_2O_2 as oxidant at temperatures below 100°C.
TL;DR: In this article, a new Horner-Emmons reagent, ethyl diphenylphosphonoacetate 1 was prepared from triethyl phosphonoacetates, PCl 5, and phenol in 60% overall yield and showed up to 99% Z-selectivity under Still's condition (KHMDS/18-crown-6).
TL;DR: In experiments using [leucine]-enkephalin as a model substrate, it is shown that PCB retains its high affinity toward avidin/streptavidin and allows rapid (< 5 min) and efficient (> 99%) photorelease of the substrate in a completely unaltered form.
Abstract: While the strong biotin-avidin interaction has been widely used for the detection of biomolecules, its irreversibility complicates their isolation. We report the synthesis of a photocleavable biotin derivative (PCB) which eliminates many limitations of existing methods. This reagent contains a biotin moiety linked through a spacer arm to a photocleavable moiety, which reacts selectively with primary amino groups on any substrate. In experiments using [leucine]-enkephalin as a model substrate, we show that PCB retains its high affinity toward avidin/streptavidin and allows rapid ( 99%) photorelease of the substrate in a completely unaltered form. Photocleavable biotins should be useful in numerous applications involving the isolation of proteins, nucleic acids, lipids, and cells.
Patent•
06 Feb 1995
TL;DR: In this paper, a diagnostic flow cell for determining the presence or amount of an analyte which may be contained in a test sample is presented. But the flow cell can be interfaced with means for detecting a signal generated by the immobilized reagent means.
Abstract: The present invention provides a diagnostic flow cell for determining the presence or amount of an analyte which may be contained in a test sample. The flow cell comprises a spacing layer having a longitudinal void disposed between a pair of opposed substrates. The spacing layer and the opposed substrates define a flow channel wherein reagent means can be immobilized. When the immobilized reagent means is contacted with an analyte, the reagent means can produce an electrically, optically, or electrically and optically detectable response to the analyte. Hence, the reagent means that is immobilized within the flow channel can comprise (i) a counter electrode, a reference electrode and a working electrode, (ii) an optically sensitive dye or (iii) a counter electrode, a reference electrode and a working electrode and an optically sensitive dye. The flow cell can be interfaced with means for introducing a test sample into and out of the flow cell's flow channel and detection means for detecting a signal generated by the immobilized reagent means. The present invention also provides methods for detecting the presence or amount of an analyte which may be contained in a test sample.
Patent•
06 Jun 1995TL;DR: An automated immunostaining apparatus with a reagent application zone and reagent supply zone has been presented in this article with a carousel slide support supporting a plurality of slide supports thereon.
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 device 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 device 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 device positioned for engaging a reagent container positioned on a container support in the reagent delivery zone and initating reagent delivery from the reagent container to a slide supported on a slide support in the reagent receiving zone.
TL;DR: In this article, a strategy to obtain intramolecular crosslinking is discussed, which consisted of three consecutive steps to direct the reaction to the formation of intramolescular crosslinks: (a) enzyme are partially modified with the bifunctional reagent in a very controlled fashion; (b) the excess of reagent is removed; and (c) the modified enzyme is incubated long-term to allow a crosslink reaction without the competition of additional single point modifications.
TL;DR: Trimethylorthoformate has been found to be an effective dehydrating solvent for the formation of imines, both in the solid phase as well as solution phase.
Patent•
07 Jun 1995
TL;DR: In this paper, an involatile reagent source liquid is flash-vaporized on a vaporization matrix structure (26) at elevated temperature, and a carrier gas mixture containing the flash vaporized source reagent is generated.
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 (26) 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 vaporization matrix structure (26) preferably has a high surface-to-volume ratio, and may suitably comprise a foraminous matrix element such as screen mesh onto which the reagent source liquid is distributed for flash vaporization. The invention is particularly useful for delivery of Group II reagents and compounds and complexes of early transition metals such as zirconium and hafnium, and may be usefully employed with Group II beta-diketonate source layers, e.g., of YBaCuO, BiSrCaCuO, and TlBaCaCuO types, as well as for forming interlayers of Group II metal fluorides between superconductor or gallium arsenide overlayers, and for depositing thin films of photonic and ferroelectric materials, e.g., BaTiO3, BaxSr1-xNb2O6, and PbZr1-xTixO3.
TL;DR: In this article, three approaches are compared for the use of tris(2,2'-bipyridil)ruthenium(II), Ru(bpy) 3 3+, as a chemiluminescent reagent in flow streams.
Abstract: Three approaches are comparatively evaluated for the use of tris(2,2'-bipyridil)ruthenium(II), Ru(bpy) 3 3+ , as a chemiluminescent reagent in flow streams: (1) external generation of the reactive Ru(bpy) 3 3+ oxidation state followed by contact with the analyte, (2) in situ generation of the Ru(bpy) 3 3+ species from a solution mixture of the analyte and the Ru(bpy) 3 2+ species as it passes through the reaction/observation cell, and (3) in situ generation of the Ru(bpy) 3 3+ species from the Ru(bpy) 3 2+ species immobilized within the observation cell. Oxalate and proline were used as representative analytes for comparison of these three modes with respect to the influence of experimental variables (reagent concentration, flow rate, pH) and resulting analytical performance (detection limit, working range, measurement precision). Additionally, a comparison was made of the relative ECL intensities obtained for a variety of analytes including oxidate, amino acids, aliphatic amines, peptides, and NADH. We find that each approach has its unique set of strengths and weaknesses. The external generation mode yields the most intense emission, especially for simple aliphatic amines, but working curves have poor linearity, and emission intensities have a large dependence on solution flow rate. The in situ immobilized approach results in lower intensities but yields the widest linear dynamic ranges, is most conservative of reagent, and has a particular sensitivity advantage for proline and NADH determinations. The in situ solution mode is superior for the detection of amino acids such as hyptophan, 5-hydroxyhyptophan, and histidine and has time, convenience, and reliability advantages
Patent•
31 Mar 1995
TL;DR: A metal source reagent liquid solution as discussed by the authors is a mixture of a metal source and a solvent for the metal coordination complex, including a metal to which a ligand is coordinatively bound in a stable complex.
Abstract: A metal source reagent liquid solution, comprising: (i) at least one metal coordination complex including a metal to which is coordinatively bound at least one ligand in a stable complex, wherein the ligand is selected from the group consisting of: β-diketonates, β-ketoiminates, β-diiminates, C1 -C8 alkyl, C2 -C10 alkenyl, C2 -C15 cycloalkenyl, C6 -C10 aryl, C1 -C8 alkoxy, and fluorinated derivatives thereof; and (ii) a solvent for the metal coordination complex. The solutions are usefully employed for chemical vapor deposition of metals from the metal coordination complexes, such as Mg, Ca, Sr, Ba, Sc, Y, La, Ce, Ti, Zr, Hf, Pr, V, Nb, Ta, Nd, Cr, W, Pm, Mn, Re, Sm, Fe, Ru, Eu, Co, Rh, Ir, Gd, Ni, Tb, Cu, Dy, Ho, Al, Tl, Er, Sn, Pb, Tm, Bi, and/or Yb. The solvent may comprise glyme solvents, alkanols, organic ethers, aliphatic hydrocarbons, and/or aromatic hydrocarbons. Solutions of the invention having two or more metal coordination complexes are resistant to detrimental ligand exchange reactions which adversely affect the stability and/or volatilizability of the metal complex for CVD applications.
TL;DR: In this article, an investigation of the conditions affecting the determination of phosphate using the reduced phosphoantimonylmolybdic acid method was carried out and the results indicated that by suitable selection of reagent conditions, rapid chromophore development can be achieved.
Patent•
06 Jun 1995
TL;DR: An in vivo method and apparatus for detecting an analyte in an individual was proposed in this article. But, the method required the individual to be in contact with a sensor that was configured to retain the fluorescence reagent while allowing analyte to diffuse into and out of the sensor.
Abstract: An in vivo method and apparatus for detecting an analyte in an individual. A sensor that includes a fluorescence reagent is placed in communication with the body fluids of the individual suspected of containing the analyte in such a way that once in place said sensor does not exit the skin of the individual. The sensor is configured to retain the fluorescence reagent while allowing analyte to diffuse into and out of said sensor. The sensor is illuminated transdermally, and the fluorescence from the fluorescence reagent associated with the presence of the analyte is measured.
Patent•
14 Feb 1995TL;DR: A new group of Os(II) and Os(III) compounds useful as redox mediators in electrochemical biosensors is presented in this article, which are particularly useful as a component of a reagent for measuring analytes from a biological fluid, such as blood.
Abstract: A new group of Os(II) and Os(III) compounds useful as redox mediators in electrochemical biosensors is presented. These compounds have 1) low oxidation potential, 2) fast reaction kinetics between the electroactive center of an enzyme and the compound, 3) slow oxidation of osmium by oxygen, and 4) excellent solubility in aqueous medium. The figure shows is a cyclic voltammagram of the compound [Os(III)(bpy)2imCl]Cl2, wherein im is imidazolyl. These mediator compounds are particularly useful as a component of a reagent for measuring analytes from a biological fluid, such as blood.
TL;DR: After correction of absorbance values, FBS and BSA added to culture medium were found to depress the reduction of alamarBlue in lung fibroblasts and mesothelial cells.
TL;DR: The theoretical minimum difference between the δ 13 C of soil CO 2 and soil-respired CO 2 (a flux) was previously thought to be 4.4‰ as discussed by the authors.
Patent•
21 Apr 1995TL;DR: In this article, the substrate is contacted by a channel block having channels, selected reagents are delivered through the channels, and the process is repeated to form arrays of polymers on the substrate.
Abstract: A device for forming large arrays of polymers on a substrate (401). According to a preferred aspect of the invention, the substrate is contacted by a channel block (407) having channels (409) therein. Selected reagents are delivered through the channels, the substrate is rotated by a rotating stage (403), and the process is repeated to form arrays of polymers on the substrate. The method may be combined with light-directed methodolgies.
TL;DR: In this paper, the fluorimetric determination of mercury ions with 5,10,15,20-tetra(p-sulfonatophenyl)porphyrin in aqueous solutions and in porphyrin doped sol-gel films was investigated.
TL;DR: In this paper, an alternative way for performing Suzuki reactions is presented, where the necessary borate which is the actual nucleophile in these palladium catalyzed C-C-bond formations is prepared from 9-methoxy-9-bora-bicyclo[3.3]nonane (9-OMe- 9-BBN) and a polar organometallic reagent RM, and not as usually from a borane and a base.
TL;DR: This chapter focuses on monobromobimane (mBBr), an uncharged reagent that readily penetrates cells, 1-4 and 4- p -sulfobenzoyloxymethyl-6-bromomethy-1-3,7-dimethyl-1,5-diazabicyclo [3.3.0], an anionic re agent that does not enter cells.
Abstract: Publisher Summary This chapter discusses the determination of biothiols by bromobimane labeling and high-performance liquid chromatography (HPLC). Most thiols undergo rapid autoxidation when exposed to air at neutral or basic pH, a process that is catalyzed by heavy metals of the type found in most cells. A primary consideration in preparing and analyzing samples for thiols is to prevent their oxidative loss during the sample preparation and analysis. This can be accomplished by alkylation of the thiol group near neutral pH with the bromobimanes. The chapter focuses on monobromobimane (mBBr), an uncharged reagent that readily penetrates cells, 1-4 and 4- p -sulfobenzoyloxymethyl-6-bromomethy-1-3,7-dimethyl-1,5-diazabicyclo [3.3.0] octa-3,6-diene-2,8-dione (SBBr), an anionic reagent that does not enter cells. Many biological thiols are relatively small and ionic, which makes them easy to separate from more hydrophobic thiols but difficult to separate from each other using reversed-phase HPLC. The bimane derivatives of these ionic thiols are more hydrophobic than the thiol itself and are readily resolved by HPLC analysis on silica-based reversed-phase columns. The highly selective, rapid reactivity of bromobimanes toward thiols, the stability and fluorescence yield of the thiol derivatives, the ease of separation of the derivatives by reversed-phase HPLC, and the availability of both cell-penetrating and nonpenetrating forms make the use bromobimanes an extremely powerful approach to the analysis of low-molecular-weight biothiols.