Search results for "visual_art.visual_art_medium"

Sulfide mineral identification using laser-induced plasma spectroscopy

2003

Sulfide minerals in rock samples were identified with laser-induced plasma spectroscopy (LIPS) in the near vacuum ultraviolet spectral region. Reference spectra of pyrite, pyrrhotite, chalcopyrite, sphalerite, barite, calcite and dolomite were applied to classification of minerals in sulfur-bearing drill core samples. On the basis of the results mineral distributions in the sample were estimated. The potential of the LIPS method for in situ analysis is discussed.

Effects of organic matter complexation on partitioning of transition metals into calcite: Cave-analogue crystal growth experiments

2022

We highlight the potential for first row transition metals to carry paleohydrological signals in speleothems, and argue that these metals constitute valuable proxies for climate reconstructions. Metal availability to speleothems is hypothesised to be restricted by organic complexation, which strongly limits the free ion activity of transition metals (Co2+, Ni2+ and Cu2+) in dripwater, thereby creating a kinetic overprint on metal concentrations and isotope ratios in speleothem calcite. This study presents the results of the first cave-analogue experiments of transition metal partitioning into calcite in the absence and presence of organic ligands. The Geological Microclimate (GeoMic) system…

Stabilization of immobilized cell systems using a modified metal surface, fructose polymer levan and a high cell concentration

1998

A chalcone-based highly selective and sensitive chromofluorogenic probe for trivalent metal cations

2015

[EN] Anew chalcone-based probe for the chromofluorogenic sens-ing of trivalent (Al3 +,Fe3+,Cr3+,Ga3+,In3+and As3 +)overmono-and divalent cationsand anionsisreported. In the presence of trivalent metal cations,the probe was able to displayaremarkable color change from yellow to colorless that wasclearly visible to the naked eye. Also, the initial strongyellowemission was gradually quenched and substituted by aweaklyshifted band.

Alkyl Complexes of Group 4 Metals Containing a Tridentate-Linked Amido−Cyclopentadienyl Ligand:  Synthesis, Structure, and Reactivity Including Ethyl…

1998

A series of group 4 metal complexes M(η5:η1:η1-C5Me4SiMe2NCH2CH2X)R2 (M = Ti; R = Me, CH2Ph; M = Zr, Hf; R = Me, Et, nPr, nBu, CH2Ph, CH2SiMe3, Ph) containing the tridentate-linked amido−tetramethy...

Cation and anion recognition characteristics of open-chain polyamines containing ethylenic and propylenic chains

2002

Abstract The interaction of the polyamines 4,7,10,13-tetraazahexadecane-1,16-diamine (L1) and 4,7,10-triazatridecane-1,13-diamine (L2) with H + , Cu 2+ , Zn 2+ , Co 2+ and the nucleotides ATP, ADP and AMP has been followed by NMR and potentiometric studies performed at 298.1 K in 0.15 mol dm −3 NaClO 4 . The influence of the different sequences of hydrocarbon chains and chelate rings present in the ligands on the values of the protonation constants, the stability of the metal ion complexes as well as in the co-ordination to nucleotides is analysed. The formation of mixed complexes has been investigated for the system Cu 2+ –L1–AMP.

Synthesis and Cu(II) coordination of two new hexaamines containing alternated propylenic and ethylenic chains: Kinetic studies on pH-driven metal ion…

2006

Abstract The synthesis of the open-chain and cyclic polyamines, 1,5,8,12,15,19-hexaazaheptadecane (L1) and 2,6,9,13,16,20-hexaaza[21]-(2,6)-pyridinophane (L2), are described. The protonation constants and interaction constants with Cu(II) have been determined by potentiometric measurements carried out at 298.1 K in 0.15 mol dm −3 NaClO 4 . The values obtained are discussed as a function of the open-chain or cyclic nature of the ligands and compared with analogous polyamines containing different sets of hydrocarbon chains between the nitrogen donors. Kinetic studies on the acid-promoted dissociation of the Cu(II) complexes indicate that the mono and binuclear complexes of L1 decompose with d…

2,2’Bipyrimidine: A Useful Tool in Designing Polynuclear Complexes of Controlled Nuclearity

1996

The versatility of a simple ligand such as 2,2’-bipyrimidine (bpym) which can adopt chelating and bis(chelating) coordination modes facilitates the preparation of both mononuclear and polynuclear complexes whose nuclearity can be controlled by playing with the metal to bpym molar ratio, the nature of the counterion and the presence of additional ligands. In this work, we summarize our results dealing with the preparation and the structural and magnetic characterization of complexes between first-row transition metal ions and bpym. Examples of orbital reversal and tunable exchange in bpym-containing copper(II) complexes are presented and discussed. The influence of the number of unpaired ele…

Metallic Charge‐Transfer Salts of Bis(ethylenedithio)tetrathiafulvalene with Paramagnetic Tetrachloro(oxalato)rhenate(IV) and Tris(chloranilato)ferra…

2014

The synthesis, crystal structure and physical characterization of three radical salts of the donor bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) and tetrachloro(oxalato)rhenate(IV) {[ReCl4(C2O4)]2–} or tris(chloranilato)ferrate(III) {[Fe(C6O4Cl2)3]3–} anions are reported. The isolated salts with ReIV are (ET)[ReCl4(C2O4)] [1, monoclinic, space group C2/c with a = 18.3409(3) A, b = 10.8414(2) A, c = 11.1285(3) A, β = 99.9714(7)°, V = 2179.38(8) A3, Z = 4] and (ET)4[ReCl4(C2O4)]·C6H5CN [2, monoclinic, space group P21/c with a = 11.8549(2) A, b = 32.9079(5) A, c = 36.4154(5) A, β = 96.742(2)°, V = 14108.1(4) A3, Z = 8]. The salt with FeIII is (ET)6[Fe(C6O4Cl2)3]·(H2O)1.5·(CH2Cl2)0.5 […

Refined carotenoid analysis of the major light-harvesting complex of Mantoniella squamata

1997

The major light-harvesting complex (LHC) of the prasinophycean alga Mantoniella squamata is unique compared to other chlorophyll (Chl) a/b-binding LHC with respect to the primary protein structure and the pigmentation. Although the presence of Chl a, Chl b, a Chl c-type pigment and the xanthophylls neoxanthin, violaxanthin and prasinoxanthin was clearly determined, several carotenoids remained unidentified or were described controversially. We re-analysed the carotenoid composition and identified a new set of xanthophylls present in the LHC: uriolide, micromonol, micromonal and dihydrolutein. Additionally, one hydrophobic component was detected, presumably a xanthophyll. The pigment analysi…