No description available.

Universiẗat, Diss., 2002--München.

This study was undertaken to compare the absorption and retention of copper and zinc when supplemented to exercising horses in the form of sulfate or organic-chelate mineral supplements. Nine mature horses were used in a modified-switchback designed experiment consisting of seven 28-d periods. Horses were fed a diet consisting of 50% coastal Bermudagrass and 50% concentrate. All diets were balanced to meet the energy, protein, calcium and phosphorus requirements for horses performing moderate to intense exercise. Copper and zinc supplementation varied by period. During mineral depletion and repletion periods, horses respectively consumed diets with no supplemental mineral or Cu and Zn supplemented in the sulfate form to provide 100% of NRC (1989) values. In periods 4 and 7, horses were fed diets designed to provide 90% of NRC (1989) values for Cu and Zn supplied in the sulfate or organic-chelate forms. Horses were subjected to a standard exercise test on d 23 of periods 4 and 7 followed by a 4-d total fecal and urine collection. Blood samples were drawn every 28-d for determination of plasma Cu, Zn and ceruloplasmin concentration, and white blood cell counts and Cu,Zn-superoxide dismutase activity were evaluated in periods 4 and 7. Copper and zinc balance was determined from feed, fecal, urine and water samples obtained during the total collections in periods 4 and 7. Copper and Zn intake and fecal excretion were greater (P<0.05) for horses consuming the organic-chelate supplemented diet. Apparent Cu absorption as a percent of intake and retention as a percent of intake were also greater for this group. Plasma Cu, Zn and ceruloplasmin concentration was not different for horses consuming the two mineral supplement forms. White blood cell counts and superoxide dismutase activity were not affected by diet treatment. Formulation error and suspected sample contamination made it difficult to compare absorption and retention of Cu and Zn, but the use of a controlled repletion-depletion diet sequence appeared to be an effective experimental design component.

This study was undertaken to compare the absorption and retention of copper and zinc when supplemented to exercising horses in the form of sulfate or organic-chelate mineral supplements. Nine mature horses were used in a modified-switchback designed experiment consisting of seven 28-d periods. Horses were fed a diet consisting of 50% coastal Bermudagrass and 50% concentrate. All diets were balanced to meet the energy, protein, calcium and phosphorus requirements for horses performing moderate to intense exercise. Copper and zinc supplementation varied by period. During mineral depletion and repletion periods, horses respectively consumed diets with no supplemental mineral or Cu and Zn supplemented in the sulfate form to provide 100% of NRC (1989) values. In periods 4 and 7, horses were fed diets designed to provide 90% of NRC (1989) values for Cu and Zn supplied in the sulfate or organic-chelate forms. Horses were subjected to a standard exercise test on d 23 of periods 4 and 7 followed by a 4-d total fecal and urine collection. Blood samples were drawn every 28-d for determination of plasma Cu, Zn and ceruloplasmin concentration, and white blood cell counts and Cu,Zn-superoxide dismutase activity were evaluated in periods 4 and 7. Copper and zinc balance was determined from feed, fecal, urine and water samples obtained during the total collections in periods 4 and 7. Copper and Zn intake and fecal excretion were greater (P<0.05) for horses consuming the organic-chelate supplemented diet. Apparent Cu absorption as a percent of intake and retention as a percent of intake were also greater for this group. Plasma Cu, Zn and ceruloplasmin concentration was not different for horses consuming the two mineral supplement forms. White blood cell counts and superoxide dismutase activity were not affected by diet treatment. Formulation error and suspected sample contamination made it difficult to compare absorption and retention of Cu and Zn, but the use of a controlled repletion-depletion diet sequence appeared to be an effective experimental design component.

Universiẗat, Diss., 2003--Tübingen.

The polydentate ligands containing both thiolato and phosphino groups have been used in catalysis and enzyme mimetic studies. We have synthesized two tetradentate thiophosphine ligands : tris(2-thiophenyl)- phosphine¡]H3L1¡^ and tris(3-trimethylsilyl-2-thiophenyl)phosphine (H3L3) and one tridentate thiophosphine ligand (bis(2-thiophenyl)- phenylphosphine¡]H2L2¡^. These ligands formed a series of germanium and tin metal complexes. We are thus exploring a range of syntheses of tin and germanium complexes. The ligand H3L1 react with SnCl4 to give trimeric tin units with bridging methoxyl group and oxo group. The ligand H2L2 react with SnCl4 or GeCl4 to give ML2 type complexes. H3L3 with germanium and tin metal complexes were synthesized and characterised by NMR spectra and mass spectra. We also obtained crystal structure of complexes GeCl(L3) and GeEt(L3). The structure was trigonal bipyramidal.

The objective of this thesis is to prepare new photochromic N,C-chelate four-coordinate organoboron compounds and investigate their photophysical and photochemical properties. Phenylpyridine-based organoboron compound (PhPyBMes2) was prepared and studied with NMR, X-ray, and UV-Vis. Experimental and theoretical results established that PhPyBMes2 is photochromic and the photoisomerization process involves a reversible intramolecular C-C bond formation/breaking. The structure of the dark colored isomer of PhPyBMes2 was established by 2D NMR experiments and computational studies. The discovery of the photochromic behavior of PhPyBMes2 led to the investigation of other phenylpyridine-based organoboron compounds. A series of substituted PhPyBMes2 compounds were synthesized with substituents on the phenyl ring or the pyridine ring of the N,C-chelate. Two other compounds were synthesized by substituting the mesityl rings in PhPyBMes2 with phenyl or pentaflurophenyl rings. The photophysical and photochemical properties of these compounds were studied by NMR, UV-Vis, and DFT/TD-DFT. The studies established that the steric hindrance imposed by the mesityl groups and the nature of substituents on the N,C-chelate have substantial effects on the photoisomerization process. New organoboron compounds based on N,C-chelates other than phenylpyridine were prepared and their photochemical and photophysical properties studied using NMR, UV-Vis, and DFT/TD-DFT. The phenyl group in the N,C-chelate was replaced by TMS-furan, TMS-thiophene, benzofuran, benzothiophene, and N-phenyl pyridylindole groups. The conducted studies show that these new compounds have photochromic properties similar to those of phenylpyridine-based compounds. Crystals of the dark isomer of the N-phenyl pyridylindole organoboron compound were successfully grown and the structure of the dark isomer was determined by X-ray diffraction. New organoboron compounds based on phenyl-benzoxazole and phenyl-benzothiazole have been also prepared and studied. The photoisomerization of these compounds is similar to the other N,C-chelate organoboron compounds but their thermal behavior is different. / Thesis (Ph.D, Chemistry) -- Queen's University, 2011-08-22 11:50:50.811

Würzburg, Univ., Diss., 2009

The development of whitening of the youngest leaves of actively growing ivy geranium (Pelargonium peltatum L.) has been observed as the season changes from late spring to summer. This study was conducted to determine the specific environmental causes of whitening, if micronutrients deficiencies cause similar whitening, whether low night temperatures can reverse whitening, and whether salicylic acid affects growth and whitening in ivy geraniums. Two cultivars, ‘Beach’ and ‘Butterfly’, with different susceptibility to whitening were chosen for this study. Elevated air temperature, but not elevated root-zone temperature, was found to be the environmental cause of whitening in ivy geranium. Elevated air temperatures severely reduced plant growth, leaf area, fresh weight, and dry weight in both cultivars. Elevated air temperature reduced photosynthetic pigments and their ratios in ivy geranium. Carotenoids and pheophytins decreased in ‘Butterfly’ at elevated air temperature. Foliar total Fe levels indicated no inhibition of Fe-uptake at elevated temperatures. Applications of Fe-chelate at elevated temperatures helped chlorophyll synthesis in ivy geraniums. Deficiency treatments of all micronutrients, Fe, Mn, Zn, S or Mg did not result in whitening in either cultivar of ivy geraniums. Salicylic acid did not affect whitening of ivy geraniums. It did not affect growth, leaf area, fresh or dry (stem, leaf or total) weight, fresh: dry weight ratio, leaf area ratio, specific leaf area or foliar nutrient (Fe, Mn, Zn, Mg and S) content in either cultivar. Cultivars varied in their response to low night temperature. ‘Beach’ reduced its plant growth and fresh to dry weight ratio whereas ‘Butterfly’ did not. Fe-chelate application did not reduce growth, leaf area, fresh weight, dry weight or fresh:dry weight ratio of either cultivar. Although Fe-application did not reduce whitening in ivy geraniums, it helped to preserve chlorophyll, particularly chlorophyll b as indicated by Chl a:b ratio in ‘Beach’. Whitening in ivy geranium is a heat stress response initially exhibited by young, developing leaves and is caused by elevated air temperatures. Whitening is the result of impaired photosynthetic pigments synthesis and/or degradation.

Tri(2-thiophenyl)phosphine (P(C6H4-2-SH)3, PS3) was designed at 1989. Recently chemists use this ligand for enzyme models because it provides rich sulfur environment. Some chemists use PS3 to synthesize novel metal complexes. Others study the transmetalation of PS3 tin complexes with FeCl3. As a continuation of our long time interest in these tin complexes as alkylation reagents, this thesis reports the synthesis and characterization of the tin-PS3 complexes. Reactions using SnCl3Me or SnCl3Bu as metal sources when dissolved in DMSO gave DMSO adduct of PS3 tin complex while sublimation gave reductive elimination products with alkyl groups transferred onto sulfur atom. The butyl transferred product and its methyl analogous are similar in morphology but different in skeletal arrangement. Reaction of SnCl4 with PS3 gave two different crystals after long standing. One is the hydrolysed product, [Sn(OH)(PS3)]2, with bridging hydroxyl groups and thiolate groups. The other is the product with oxidized ligand. Reaction of SnBr4 with PS3 gave analogous ligand-oxidized product. Reaction of two mole of SnCl3Bu with PS3 resulted in a bimetallic tin complex.