Search results for "Alko"
showing 10 items of 423 documents
Liquid crystals in the series of 2,4,6-tristyryl-1,3,5-triazines
2004
Abstract Alkaline condensation reactions of 2,4,6-trimethyl-1,3,5-triazine ( 1 ) and substituted benzaldehydes ( 2a – n ) yield 2,4,6-tristyryl-1,3,5-triazines ( 3a – n ). A sufficient number and length of the alkoxy chains at the benzene rings provide liquid crystalline phases Col hd . A special structure was found for compound 3i with 9 hexyloxy chains; it exists in the solid state in a helical columnar arrangement, which is transformed by heating to a hexagonal columnar mesophase. Irradiation of the mesophases of 3i – 3m leads to partial cyclodimerization reactions, which cause different textures and lower the clearing points. The border line between the irradiated and the unirradiated z…
Mesomorphic Donor-Acceptor-substituted 1,4-Distyrylbenzenes
2009
Conjugated oligomers with terminal donor-acceptor substitution attract increasing attention in organic chemistry because of their outstanding and not seldom unexpected properties in materials science [1 – 4]. Although a variety of oligo(1,4-phenylene-vinylene)s with terminal donor-acceptor substitution (DAOPVs 1, Scheme 1) are known [5 – 22], the number of thermotropic liquid crystals among them is very low and is confined to monomers (n = 1), that means to certain push-pull substituted (E)-stilbenes [23 – 31]. The behavior of conjugatedmolecules, which are highly polar and form mesophases by self-organization, is very interesting for various applications of liquid crystals [3]. A big disad…
Activation and translocation of p38 mitogen-activated protein kinase after stimulation of monocytes with contact sensitizers.
2002
Recently we described the induction of tyrosine phosphorylation by contact sensitizers as an early molecular event during the activation of antigen- presenting cells. In this study, the role of the p38 mitogen-activated protein kinase for the activation of human monocytes after exposure to four structurally unrelated contact sensitizers was analyzed in comparison with the irritant benzalkonium chloride and an inductor of oxidative stress (H 2 O 2 ) using immunofluorescence, Western blotting, and enzyme-linked immunosorbent assay techniques. Bio chemical analysis revealed a translocation of p38 from the cytoplasm to the detergent-resistant cell fraction only upon stimulation with contact sen…
A liquid alkoxide precursor for the atomic layer deposition of aluminum oxide films
2020
For large-scale atomic layer deposition (ALD) of alumina, the most commonly used alkyl precursor trimethylaluminum poses safety issues due to its pyrophoric nature. In this work, the authors have investigated a liquid alkoxide, aluminum tri-sec-butoxide (ATSB), as a precursor for ALD deposition of alumina. ATSB is thermally stable and the liquid nature facilitates handling in a bubbler and potentially enables liquid injection toward upscaling. Both thermal and plasma enhanced ALD processes are investigated in a vacuum type reactor by using water, oxygen plasma, and water plasma as coreactants. All processes achieved ALD deposition at a growth rate of 1-1.4 angstrom/cycle for substrate tempe…
Impact of biocide treatments on the bacterial communities of the Lascaux Cave.
2009
The Lascaux Cave contains a remarkable set of paintings from the Upper Palaeolithic. Shortly after discovery in 1940, the cave was modified for public viewing and, in 2001, was invaded by a Fusarium solani species complex. Benzalkonium chloride was used from 2001 to 2004 to eliminate the fungal outbreak. In this study, we carried out a sampling in most of the cave halls and galleries. Sequence analysis and isolation methods detected that the most abundant genera of bacteria were Ralstonia and Pseudomonas. We suggest that, as a result of years of benzalkonium chloride treatments, the indigenous microbial community has been replaced by microbial populations selected by biocide application.
Bacteria and free-living amoeba in the Lascaux Cave.
2008
3 pages, 1 table, 18 references. The collaboration of the Lascaux restoration team is highly appreciated. We thank Marisa Chelius for valuable comments on the manuscript.
DFT analysis of titanium complexes with oxygen-containing bidentate ligands
2003
Strength of the TiO co-ordinate bond in several titanium complexes with bidentate ligands has been investigated by means of DFT. Mutual interaction of particular donors and their influence on Lewis acidity of the central atom have also been studied. The energy of ligand binding ranges from −19 to −454 kJ/mol, depending on the kind of donors. Calculations confirm that a strong donor, alkoxide anion, co-ordinatively saturates the titanium and makes binding of new ligands less exoenergetic. On the contrary, two oxygen atoms of similar donor number do not have much influence on each other. Strength of the TiO bonds in titanium complexes with certain oxygen-containing bidentate ligands has bee…
Synthesis and structural investigations on R2Sn(IV)-D-aldonic acid complexes (R = methyl; butyl). Their effect on a new toxicity test organism,Liza s…
2008
Eight R2Sn(IV)-D-aldonate complexes [(R = Me, Bu; D-aldonate = D-galactonate2− (Galn), D-Gluconate2− (Glun), D-Gulonate2− (Guln), D-Ribonate2− (Ribn)], five of which are new derivatives, have been synthesized and structurally characterized both in solid and solution state by IR, 119Sn Mossbauer and 1H, 13C, 119Sn NMR spectroscopies, showing that ligands act as dianonic chelating agents. In solution phase, NMR data suggest that the bidentate chelation is attained by the O1 carboxylate and the vicinal O2 alkoxide atoms, which can be dynamically extended to a third binding site (O4) competing with O2. In Me2Sn(IV)-D-gluconate complex the occurrence of a self-association process leading to a di…
Ion mobility spectrometry as a fast analytical tool in benzalkonium chloride homologs determination.
2017
Abstract A novel procedure is proposed for the determination by ion mobility spectrometry (IMS) of C 12 , C 14 and C 16 benzalkonium chloride (BAC) homologs. The proposed method requires minimum sample treatment and the measurement was made in less than one minute. A high sensitivity was obtained for BAC determination by IMS with limit of detection values from 37 to 69 µg L −1 . Accuracy of the proposed methodology was evaluated through the analysis of aqueous and alcoholic samples spiked with BAC at concentration levels from 0.002% to 20% (w/v), providing recovery values from 91% to 104%. BAC was determined in sanitary alcohols, nasal sprays, postharvest products, algaecides, and treated s…
A tandem-flow assembly for the chemiluminometric determination of hydroquinone
2003
A direct chemiluminescent procedure for determination of hydroquinone based on the emergent flow methodology known as multicommutation or tandem-flow is presented for first time. The manifold was based on a set of three channels and three solenoid valves; and, the determination was performed at 60degreesC and at flow-rate of 7.5 ml min(-1). The complete cycle lasted 35 s, which resulted in a sample flow trough of 103 h(-1). The chemical process was the hydroquinone oxidation with the system sulphuric acid-potassium permanganate; and the light emission was clearly enhanced by the presence of quinine sulphate and benzalkonium chloride reaching a detection limit of 30 Rg l(-1). The dynamic int…