Search results for "Sodium"
showing 10 items of 1605 documents
Sodium-mediated manganation: direct mono- and dimanganation of benzene and synthesis of a transition-metal inverse-crown complex.
2007
Inside out approach: Twofold deprotonation of benzene by a sodium monoalkyl bisamido manganate(II) reagent derived from BuNa, 2,2,6,6-tetramethylpiperidine, and Mn(CH2SiMe3)2 has produced the first inverse-crown complex in which the transition-metal atoms are incorporated in the host (see X-ray structure, blue N, green Na, purple Mn). Variable-temperature magnetization measurements show that the complex is antiferromagnetic.
Radioactively labelled epoxides. Part VI. tritium-labelled mono- and dimethyl substituted phenyl oxiranes (styrene oxides)
1988
Tritium-labelled (E)- and (Z)-2,3-dimethyl-2-phenyl oxirane 4, (E)- and (Z)-2-methyl-3-phenyl oxirane 7 and 2,2-dimethyl-3-phenyl oxirane 11 have been prepared by reduction of the corresponding bromoketones with sodium borotritide to the corresponding bromohydrins followed by cyclization to the oxiranes. These oxiranes were successfully used as diagnostic substrates to distinguish between different forms of epoxide hydrolase and glutathione transferase.
Inhibition of the precipitation of barium salts in sodium dodecyl sulfate/0.1 M HCl/n-pentanol microemulsions and liquid crystals
1989
Abstract The phase ternary diagram of the sodium dodecyl sulfate (SDS)/0.1 M HCl/n-pentanol system is studied. Three monophase regions were observed: water rich and n-pentanol rich microemulsions, and a liquid crystal. These media have a strong ability to control the rate of crystal growth of barium sulfate and barium dodecyl sulfate, the precipitation being totally inhibited in the liquid crystal region.
Structural characterisation of silica supported CoMo catalysts by UV Raman spectroscopy, XPS and X-ray diffraction techniques
2002
The structure of Co-Mo catalysts supported on commercial silica, doped with various amounts of sodium ions, was investigated by means of X-ray diffraction (XRD), UV-Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Two series of samples were considered. One series was prepared by classic incipient wet impregnation (WI) and the other series by co-impregnation in the presence of nitrilotriacetic acid (NTA). The effect of sodium on the catalyst structure depended on the preparation procedure: in the case of the WI catalysts, sodium promoted the transformation of the polymolybdate species into monomolybdate Na2MoO4; in the case of the NTA prepared samples, sodium induced transforma…
Spectrophotometric determination of fluoride in fluoride-bearing minerals after decomposition by fusion with sodium hydroxide
1984
The decomposition of highly insoluble minerals (fluorspar and cryolite) by fusion with molten alkali-metal hydroxides is studied. The introduction of additives such as aluminium compounds or sodium peroxide to obtain total liberation of fluoride from calcium fluoride samples, is tested. The fusion is done in a silver crucible with a Bunsen burner. The cooled melt is easily soluble, giving solutions suitable for spectrophotometric fluoride determination by the Zr(IV)-fluoride-Erichrome Cyanine R method.
Vanadyl phosphate dihydrate, a solid acid: the role of water in VOPO4�2H2O and its sodium derivatives Na x (VIV x VV 1?x O)PO4�(2?x)H2O
1988
Sodium-containing intercalates having as general formula Na x VOPOP4·(2−x)H2O (0.25≤x<0.50) have been obtained and characterized. Orthorhombic phases, which essentially maintain the structure of the layered oxide hydrate VOPO4·2H2O result. Intercalated sodium ions act as ‘pillars’. The presence of H3O+ ions in the parent VOPO4·2H2O and also in some reduced phases, is detected. The understanding of the structural role of the water molecules is advanced and the topotactic dehydration/rehydration processes are studied. The formation of a new metastable VOPO4·H2O phase is established.
A preliminary approach to mineral intake in the Spanish diet established from analysis of the composition of university canteen menus
2012
Abstract The concentration of mineral elements in complete menus has in Spain been determined in order to establish the levels of essential and toxic elements and their contribution to the maximum recommended intake. Thirteen university canteen menus obtained from the Burjassot campus, in Valencia, were analysed to establish a first approach on mineral composition in the Spanish diet. The menus were composed of a mixture of cereals, meat, fish, vegetables, fruits and dairy products. Samples were crushed, homogenized and lyophilized, and 25 elements were determinated by inductively coupled plasma optical emission spectroscopy (ICP-OES) after digestion of samples in a microwave oven. Menu sam…
Durch elektronenübertragung initiierte diradikalische polykombination zu linearen und cyclischen polyanionen, 2. Umsetzung von bis[4-(1-phenylvinyl)p…
1975
Die Umsetzung von Bis[4-(1-phenylvinyl)phenyl]methan (1) mit Natrium in THF wird beschrieben. Die protonierten und methylierten Reaktionsprodukte werden durch GPC, NMR- und Massenspektren charakterisiert. Die Bildung von linearen Produkten und von Oligo-anion-paracycolophanen wird diskutiert. The reaction of bis[4-(1-phenylvinyl)phenyl]methane (1) with sodium in THF is described. The protonated and methylated products are characterized by GPC, NMR, and mass spectra. The formation of linear products and of oligo-anion-paracyclophanes is discussed.
Industrial and culinary practice effects on biologically active polyamines level in turkey meat
2021
Polyamines, including putrescine, spermidine, and spermine, are biological compounds present in nearly all food items. Their desirable physiological effects include cell division and growth. Hence, are undesirable in the diet of patients with tumor. This study aimed to assess the impact of curing agents (sodium chloride (0–2 g), sodium nitrite (0–200 ppm), sodium polyphosphate (0–0.5 g), and ascorbic acid (0–500 ppm)), cooking (frying (180°C), and boiling (100°C)) on polyamine contents in turkey breast meat using response surface methodology based on central composite design and dispersive liquid-liquid microextraction. Postprocessing changes were investigated using a high-performance liqui…
Kinetic modeling of ion conduction in KcsA potassium channel.
2005
KcsA constitutes a potassium channel of known structure that shows both high conduction rates and selectivity among monovalent cations. A kinetic model for ion conduction through this channel that assumes rapid ion transport within the filter has recently been presented by Nelson. In a recent, brief communication, we used the model to provide preliminary explanations to the experimental current-voltage J-V and conductance-concentration g-S curves obtained for a series of monovalent ions (K(+),Tl(+), and Rb(+)). We did not assume rapid ion transport in the calculations, since ion transport within the selectivity filter could be rate limiting for ions other than native K(+). This previous wor…