Crystal structure and infrared analysis of a new trinuclear platinum(II) complex with L-cysteine

A new trinuclear platinum(II) complex with cysteine of composition [Pt(C3H6NO2S)Cl](3)center dot(C2H6SO)(3) was obtained and structurally characterized by X-ray diffraction and infrared analysis. The compound crystallizes in the trigonal system, space group R3, and is described in a hexagonal cell with a=17.739(1), c=9.531(1) and Z=3. Cysteine is coordinated to Pt(II) through the nitrogen and sulphur atoms. Each cysteine sulphur bridges between two metal atoms. A square planar coordination sphere of platinum is completed by a chlorine atom. The complex is soluble in dimethyl sulfoxide.

Compostos heterometálicos. Interação do tricarbonil com ligação W-Hg, [WCl(CO)3(bipy)(HgCl)], com tiouréias

Reactions of [WC1(CO)(3)(bipy)(HgCl)], [bipy = 2,2 -bipyridine], with thioureas were performed giving compounds of the type [WCl(CO)(3)(bipy)(HgCl)L], [L = thiourea (tu); N-methylthiourea (mtu); N,N-dimethyithiourea (dmtu)] in which the coordination sphere of the tungsten atom remained unchanged. The coordination of the thioureas to mercury atom was proved to occur in accord to infrared spectra, through the sulphur atom.

Oxidation of chalcopyrite by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans in shake flasks

Chalcopyrite oxidation was evaluated with two acidophilic thiobacilli that are important in bioleaching processes. Acidithiobacillus thiooxidans in pure culture did not oxidize CuFeS2 but oxidized externally added S in the presence of CuFeS2. Acidithiobacillus ferrooxidans released Cu2+ and soluble Fe from chalcopyrite, and the time course lead to a gradual passivation of chalcopyrite whereby Cu2+ dissolution leveled off. Fe3+ acted as a chemical oxidant in CuFeS2 leaching and was reduced to Fe2+. Parallel bacterial re-oxidation of Fe2+ contributed to a high Fe3+/Fe2+ ratio and an increase in redox potential. Chemical oxidation of chalcopyrite was slow compared with A. ferrooxidans-initiated solubilization. X-ray analysis revealed new solid phases: (i) jarosite, found in solids from A. ferrooxidans cultures and in chemical controls that initially received Fe2+ or Fe3+, and (ii) S-0, found mostly in iron-amended A. ferrooxidans culture and the corresponding chemical controls. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Precipitation chemistry and wet deposition in Kruger National Park, South Africa

The chemical composition, as well as the sources contributing to rainwater chemistry have been determined at Skukuza, in the Kruger National Park, South Africa. Major inorganic and organic ions were determined in 93 rainwater samples collected using an automated wet-only sampler from July 1999 to June 2002. The results indicate that the rain is acidic and the averaged precipitation pH was 4.72. This acidity results from a mixture of mineral acids (82%, of which 50% is H2SO4) and organic acids (18%). Most of the H2SO4 component can be attributed to the emissions of sulphur dioxide from the industrial region on the Highveld. The wet deposition of S and N is 5.9 kgS.ha(-1).yr(-1) and 2.8 kgN.ha(-1).yr(-1), respectively. The N deposition was mainly in the form of NH4+. Terrigenous, sea salt component, nitrogenous and anthropogenic pollutants have been identified as potential sources of chemical components in rainwater. The results are compared to observations from other African regions.

Tolerance to copper and zinc of Acidithiobacillus thiooxidans isolated from sewage sludge

The effect of copper and zinc ions on sulphur oxidation by Acidithiobacillus thiooxidans, strain SFR01, isolated from anaerobic sewage sludge was assessed, resulting in tolerance levels up to 20 and 200 mmol l(-1) for copper and zinc, respectively. The tolerance levels obtained were higher than the concentration of copper and zinc usually found in the collected sewage sludge. The tolerance levels obtained indicate no constraints for sludge bioleaching of those metals due to their toxicities to the indigenous A. thiooxidans.

Solubilization profiles of metal ions from bioleaching of sewage sludge as a function of pH

Two patterns of solubilization of metal ions resulting from bioleaching of sewage sludge by sulphur-oxidizing Thiobacillus spp. were established as a function of pH. Chromium and copper ions required a pH of 2-3 to initiate their solubilization, whereas nickel and zinc ions had their solubilization initiated at pH 6-6.5. The patterns obtained were independent of the sludge solids concentrations investigated (10, 17, 25, 32.5 and 40 g l(-1)).

Determination of organochlorine pesticides and polychlorinated biphenyls residues in municipal solid waste compost by gas chromatography with electron-capture detection

A simple and efficient method for the simultaneous gas chromatographic determination of ten organochlorine pesticides (alpha-HCH, beta-HCH, gamma-HCH, p,p'-DDT, o,p'-DDT, p,p'-DDD, p,p'-DDE, aldrin, endrin, and dieldrin) and six congeners of PCBs (PCB 28, 52, 118, 138, 153, and 180) in municipal solid waste compost is described. The procedure involves a solid-phase dispersion matrix using celite as dispersant sorbent, alumina as clean up sorbent and hexane-dichloromethane (7:3, v/v) mixture as eluting solvent. An additional purification step with copper was necessary to eliminate sulphur. Analysis of the sample was performed by GC-ECD. The method was validated with fortified samples at two concentration levels (0.025 and 0.05 mg kg(-1)). Average recovery ranged from 77 to 121% with relative standard deviation between 1 and 18%. The detection limits, which ranged from 0.003 to 0.01 mg kg-1, were lower than those established by the Baden-Wurttemberg directive (0.033 mg kg(-1)).

Synthesis and solid-state structural characterization of bis (thiocyanatemercury)tetracarbonyliron

The bis (thiocyanatemercury)tetracarbonyliron, [Fe(CO)4(HgSCN)2], was prepared from [Fe(CO) 5] and Hg(SCN)2, and studied by IR spectroscopy and X-ray diffraction. The compound crystallizes in the tetragonal space group I4,1/a. The unit cell, with dimensions of a = 13.778(3), c = 13.234(3) Å, V = 2512.3(9) Å3, contains four molecules. The iron atom is octahedrally coordinated by four carbonyl groups and two mercury atoms in cis positions. The coordination of the mercury atoms is distorted square-planar, since, besides mercury-iron and mercury-sulphur bonds, there are also mercury-mercury and mercury-nitrogen interactions. The FeHg distance is 2.506(5)Å and the HgFeHg angle is 78.0(1)°. © 1987.

Sulfur and carbon isotopes in scapolite-bearing granulites of the São José do Rio Pardo area, Brazil

Sulfur and carbon isotope compositions of ten scapolites from granulite-facies rocks of the São José do Rio Pardo area, Guaxupé Complex, Brazil, were measured. Scapolite is the primary and major rock-forming mineral in these rocks (up to 40 volume %). The isotopic composition of the sulfate and carbonate group in the scapolite structure has δ34S values of +1.0‰ to +6.7‰, and δ13C values of -14.3‰ to -6.3‰, respectively. The sulfur isotope data may be related to an upper mantle (external) or lower crustal (internal) source for the sulfur, whereas the carbon appears to have been derived from an internal source. Thus, the carbon and sulfur isotope data can be explained without invoking an external (mantle) source. © 1993.

Synthesis and structural studies of bis(1,10-phenanthrolinethiocyanatemercury) tetracarbonyliron

The bis(1,10-phenanthrolinethiocyanatemercury)tetracarbonyliron was prepared from bis(thiocyanatemercury)tetracarbonyliron and 1,10-phenanthroline and crystallized from hot acetone solution as [Fe(CO)4(HgSCN)2(phen)2]·C3H6O, which was subjected to a full IR and X-ray crystallographic characterization. The iron atom is octahedrally coordinated by four carbonyl groups and two mercury atoms in cis positions. The coordination geometry of the mercury atoms is a distorted square-based pyramid since each one is coordinated to one iron, one sulphur, one mercury and two nitrogen atoms. The FeHg distances are 2.549(3) and 2.564(3) Å, and the HgFeHg angle is 78.01(9)°. © 1992.

Substituição do farelo de soja pelo de guandu na alimentação de frangos de corte

The objective of this work was to evaluate the nutritive value of pigeon pea meal (PPM) with methionine substituting soybean meal (SM) in diets for 1-28 day-old broiler chicks. The experimental design was that of random blocks, in a 3 × 3 factorial scheme with three substitution levels - 15,30 and 45% - and three methionine supplementation levels in relation to the requirements, that is: 100, 66 and 33%, with four repetitions. It was found that PPM treated for 20 minutes at 100°C substituted up to 30% of the SM, even without methionine supplementation, in relation to liveweight (p<0.01), to food conversion and to the efficiency of utilization of metabolizable energy and to protein (p<0.05). At the 66% level of methionine supplementation, the same results as for these parameters were obtained at all of the levels of substitution of SM by PPM. The 30% or 45% substitution of SM protein by that of PPM affected (p<0.01) the efficiency of methionine utilization. The sulphur amino acid utilization efficiency was affected (p<0.01) beginning at 66% methionine supplementation in the diets.

Synthesis, characterization and thermal decomposition of [Pd2 (C2-dmba) (μ-SO4) (μ-SO4) SO22]

The bridged sulphate complex [Pd2 (C2,dmba) (μ-SO4) (SO2)2] has been obtained by reacting a saturated solution of SO2 in methanol and the cyclometallated compound [Pd(C2,N-dmba)(μ-N3)]2; (dmba = N,N-dimethylbenzylamine), at room temperature for 24 h. Reaction product was characterized by elemental analysis, NMR comprising 13C{1H} and 1H nuclei and I.R. spectrum's measurements. Thermal behavior has been investigated and residual products identified by X-ray powder diffraction.

Growth parameters and nutrient content in four multipurpose tree species with potential characteristics for agroforestry systems in a Cerrado region in Botucatu, São Paulo State, Brazil

In order to evaluate growth characteristics, adaptability, biomass production, nutrient recycling, nutrient distribution and the ability to regenerate degraded land, a trial using four multipurpose tree species (Leucaena leucocephala, Leucaena diversifolia, Acacia melanoxylon and Mimosa scabrella) was undertaken over two years in a distrophic red yellow latosol (oxisol) following a randomized block experimental design with four replications. At the age of two years, A. melanoxylon and L. diversifolia were the tallest species (5.25 and 4.97 m, respectively) and A. melanoxylon and M. scabrella had the largest diameters at 20 cm from tree base. Mimosa scabrella and A. melanoxylon had the highest dry matter production and quantity of nutrients in the above ground biomass. In all species, the highest nutrient contents were found in the leaves, followed by branches and stems. From all species, the highest Nutrient Utilization Efficiency Indexes were obtained for sulphur, phosphorous, and magnesium; L. diversifolia was the most efficient for nitrogen, potassium, calcium, sulphur, and manganese, while A. melanoxylon was the most efficient for phosphorus, magnesium, boron, iron, and zinc. Litter production levels over a three month period were as follows: M. scabrella > A. melanoxylon > L. diversifolia > L. leucocephala. Litter nutrient content was higher in M. scabrella than in the other species.

Maize germ recovery and quality using the intermittent milling and dynamic steeping process

The intermittent milling and dynamic steeping (IMDS) process is an alternative method developed for wet milling of maize. In this process, the steeping stage can be reduced to 5 h by soaking maize in water at 60°C for 2 h and cracking the kernels to remove solution components diffusional barriers with minimum germ damage. Maize was dynamically steeped in solutions with 0.0, 0.1, and 0.2% sulphur dioxide (SO2) and 0.00, 0.55% lactic acid. Germ recovery, germ damage, fibre in germ, oil content and uncracked kernels were determined. A conventional steeping procedure was also performed. Germ recovery was higher for all tests using both SO2 and lactic acid than for the others with best germ yield for concentrations of 0.2% SO2 and 0.55% lactic acid. Germ damage ranged from 7.4 to 18.2% for all tests. The presence of lactic acid in the steeping solution decreased the amount of fibre in germ fraction. Germ oil content ranged from 39.3% (0-0% SO2, 0.55% lactic acid) to 44.0% (0.2% SO2, 0.55% lactic acid) for all treatments using IMDS. The smallest difference was 5.5% between IMDS (0.2% SO2, 0.55% lactic acid) and the conventional 36 h steeping process. An average of 1.3% of kernels remained uncracked after IMDS process. © 2002 Silsoe Research Institute. Published by Elsevier Science Ltd. All rights reserved.

Assessment of anaerobic sewage sludge quality for agricultural application after metal bioleaching

The effects of metal bioleaching on nutrient solubilization, especially nitrogen and phosphorous, from anaerobically-digested sewage sludge were investigated in this work. The assessment of the sanitary quality of the anaerobic sludge after bioleaching was also carried out by enumerating indicator (total coliforms, fecal coliforms, and fecal streptococci) and total heterotrophic bacteria. The experiments of bioleaching were performed using indigenous sulphur-oxidizing bacteria (Thiobacillus spp.) as inoculum and samples of anaerobically-digested sludge. Nitrogen and phosphorous solubilization from sewage sludge was assessed by measuring, respectively, the concentration of Total Kjeldahl Nitrogen, ammonia, nitrate/nitrite, and soluble and total phosphorous before and after the bioleaching assays. At the end of the experiment, after 4 days of incubation (final pH of 1.4), the following metal solubilization yields were obtained: zinc, 91%; nickel, 87%; copper, 79%; lead, 52%; and chromium, 42%. As a result of sludge acidification, the viable counts of selected indicator bacteria were decreased to below the detection limit (4 × 103 cfu 100 ml-1), followed by an increase in the mineral fraction of nitrogen (from 6 to 10%) and in the soluble fraction of phosphorous (from 15 to 30%). Although some loss of sludge nutrients can occur during solid-liquid separation following bioleaching, its beneficial effects as metal removal and reduction of pathogenic bacteria are sufficient to consider the potential of this treatment before sludge disposal onto agricultural fields.