Search results for "Solid"
showing 10 items of 3575 documents
Synthesis and thermal decomposition studies of homo- and heteroleptic tin(iv) thiolates and dithiocarbamates: molecular precursors for tin sulfides
2002
The syntheses and X-ray structures of novel heteroleptic thiolate/dithiocarbamate derivatives (Et2NCS2)2(RS)2Sn (R = Cy, CH2CF3) have been examined and their thermal decompositions compared with those of selected tin(II) and tin(IV) dithiocarbamates. The heteroleptic species decompose to SnS by initial elimination of RSSR to afford (Et2NCS2)2Sn and subsequent loss of [Et2NC(S)]2S. In contrast, (Et2NCS2)4Sn decomposes via [(Et2NCS2)2SnS]2, whose structure has been determined, and finally to SnS2 by sequential elimination of [Et2NC(S)]2S. The two families of compounds, (R2NCS2)4Sn and (Et2NCS2)2(RS)2Sn, thus provide single-source materials for bulk SnS2 and SnS, respectively, by virtue of the…
Synthesis of V-ZrSiO4 solid solutions
1990
This letter describes the results of the preparation of V-ZrSiO 4 solid solutions from a sol or alkoxide and solute salts. This technique allows a greater degree of product formation to be achieved at lower temperatures, as well as the possibility of studying the characteristics of possible solid solutions
ChemInform Abstract: Highlights on Contemporary Recognition and Sensing of Fluoride Anion in Solution and in the Solid State
2013
The fluoride anion has recently gained well deserved attention among the scientific community for its importance in many fields of human activities, but also for concerns on its effect on health and the environment. Although surprisingly overlooked in systematic studies in the past, fluoride has nowadays become a topical target in the field of anion recognition. A multitude of scientific reports are published every year where the establishment of efficient and specific interaction with fluoride is sought in polar and aqueous media. Here, the emphasis is directed to a detailed description of the most interesting contemporary studies in the field, with a particular focus given to those publis…
The orientational glass state of argon:Nitrogen and cyanide mixed crystals
1990
Abstract Solid solutions of Ar:N 2 and ( KBr ) 1− x ( KCN ) x mixed crystals show a so-called orientational glass state where the orientations of the aspherical species, N 2 respectively CN - , are frozen in random patterns. The main experimental characteristics of this state and the pertinent theoretical concepts are discussed.
1973
The mechanism of radiation-induced polymerizations in the solid state has been a subject mostly open to speculation. As radiation usually generates several kinds of active species (radicals and ions) it is difficult to find out, which of these actually causes polymerization. We have developped a method distinguishing between cationic and anionic active centers. Cationic polymerizations are terminated by addition of a base such as sodium alkoxide in a suitable solvent. The alkoxide is incorporated into the polymer as an endgroup. This endgroup is determined analytically after isolation and purification of the polymer. The incorporation of alkoxy endgroups into the polymer is a proof of the o…
Determination of Homovanillic Acid in Human Plasma Using HPLC with Electrochemical Detection and Automated Solid Phase Extraction
1993
Abstract An isocratic HPLC method with electrochemical detection for the quantification of homovanillic acid (HVA) is described. The method included automated solid phase extraction on C-18-reversed phase material, followed by separation on a 3-μm Nucleosil 100 C18 column (250 mm × 4.6 mm I. D.) with a 100 mM citric acid solution (pH 6.6) containing 4% acetonitrile (v/v) as eluent at a flow rate of 0.6 ml/min. Isovanillinic acid served as internal standard. Extractability of both analytes was ca. 80 %. After extraction of 1 ml of plasma, coefficients of variation of replicate analyses were below 10 % in the naturally occuring concentration range.
Synthesis and photodimerisation of tetrabenzo[ab,f,jk,o][18]annulenes
1999
Abstract The tetrabenzo[ab,f,jk,o][18]annulenes 7a,b, generated in a 5-step synthesis, show photodimerisation and -oligomerisation reactions in the solid state and in solution. The state of aggregation determines the reaction route. Whereas the cyclodimer 8a has a simple cyclobutane structure, the dimer 8b is a highly symmetrical cyclophane.
NMR Solution Conformation of the Proposed Recombin Like Structure D(CCGCGG)2
1997
Long repeated stretches of d(CCG) trinucleotide are the crucial mutation of gen that causes hereditary form of mental retardation (fragile X-syndrome). Moreover, the alternating (CG) dinucleotide is one of the candidates for Z-DNA conformation. Both sequences are part of the hexanucleotide d(CCGCGG)2- d(CCGCGG)2 forms different crystals depending on the crystallisation conditions. In one of these forms, the central alternating tetramer has a Z-DNA conformation, while the initial cytosine swings out and forms a Watson-Crick base-pair with the terminal guanine of a symmetry-related molecule. In this communication a detailed comparison between solid and solution spatial conformation by NMR of …
Comparative assessment of solid-phase extraction clean-up procedures, GC columns and perfluoroacylation reagents for determination of type B trichoth…
2005
Abstract Various solid-phase extraction (SPE) procedures for clean-up, two perfluoroacylation reagents (pentafluoropropionic anhydride (PFPA) and heptafluorobutyric anhydride (HFBA)) and two chromatographic columns (HP-1701 and HP-5) have been assessed comparatively to achieve the determination of type B trichothecenes (deoxynivalenol (DON), nivalenol (NIV), 3- and 15-acetyldeoxynivalenol (3- and 15-ADON)) in wheat grain by gas chromatography (GC)–electron-capture detection (ECD). Spiked wheat samples were extracted with acetonitrile–water (84:16, v/v). Tested SPE procedures were MycoSep 225 column, Florisil and different cartridges prepared in the laboratory with mixtures of various sorben…