The structure of two manganese hexacyanometallates II : Mn2 Fe CN 6 .8H2O and Mn2 Os CN 6 .8H2O

The crystal structures of two manganese hexacyanometallates~II!, Mn2 @Fe(CN)6#.8H2O and Mn2@Os(CN)6#.8H2O, were refined from X-ray powder diffraction data using the Rietveld method, with the reported structure for Mn2@Ru(CN)6#.8H2O used as a structural model. These compounds are isomorphous and crystallize in the monoclinic space group P21 /n. Their crystallization water is not firmly bound and can be removed without disrupting the M–CwN–Mn network. In the dehydrated complexes, the outer cation ~Mn! remains linked to only three N atoms from CN ligands while the inner cation ~Fe,Os! preserves its coordination sphere. The IR, Raman, and Mo¨ssbauer spectra for the hydrated and anhydrous forms are explained based on the refined structures. © 2002 International Centre for Diffraction Data. @DOI: 10.1154/1.1469023

Thermal decomposition of diammonium tetrachloroplatinate to form platinum nanoparticles and its application as electrodes

Pt nanoparticles were obtained via the thermal decomposition of (NH 4)2[PtCl4] (diammonium tetrachloroplatinate) by heating from room temperature to 760 °C. The thermal decomposition process was analyzed using thermogravimetric analysis (TGA) and differential thermal analysis (DTA), X-ray thermodiffraction and infrared spectroscopy. The size and structure of the platinum particles were analyzed using transmission electron microscopy (TEM). The electrochemical activity of Pt particles was assessed by cyclic voltammetry in 0.5 M H2SO4. The TGA and DTA results suggested that the thermal decomposition of the precursor proceeded in two stages: loss of NH4Cl at ∼300 °C, followed by loss of NH 4Cl and Cl2 at ∼372 °C. Metallic Pt particles were then produced at temperatures of 372 °C and above. At 760 °C, the mean ± SD size of the Pt particles was (4.1 ± 1.6) nm, as determined from TEM measurements. In cyclic voltammetry (CV) measurements, an electrode comprised of glassy carbon and Pt particles in 0.5 M H2SO4 exhibited behavior similar to that observed using a polycrystalline Pt electrode. © 2009 Springer Science+Business Media, LLC

ACID HYDROLYSIS OF COMPOSITES BASED ON CORN STARCH AND TRIMETHYLENE GLYCOL AS PLASTICIZER

Corn starch-based films with trimethyilene glycol (1,3-propanediol) as plasticizer were prepared with the castingtechnique and subject to acid hydrolysis (HCl 1.0 M) at 20 oC. The film degradation was monitored by changes in surfacemorphology, crystallinity, thermal properties and surface wettability. In the first two days, the hydrolysis showed lowadvance to subsequently exhibit a huge increase of the reaction rate. It suggested that surface erosion is the main mechanisminvolved in the film degradation. XRD showed the presence of poly-1,3-propanediol, attributed to condensation reactionof plasticizer in acidic conditions. Thermal analysis showed two endothermic peaks at 110-120 oC attributed to meltingof crystallized amylopectin and to a lesser extent co-crystallized amylose and amylopectin. The temperature of thesepeaks was not affected by hydrolysis time, supporting the idea that hydrolysis reactions are constrained to the film surface.Contact angle measurements indicated a significant decrease of hydrophobicity caused by fractionation of starch chains

Textural Analysis of Sulphated ZrO–SiO Sol–Gel Catalytic Supports by N Sorption and X-Ray Diffraction

The textural properties of sulphated ZrO 2 –SiO 2 catalytic supports of different compositions were investigated through N 2 sorption and X-ray diffraction (conventional and SAXS) methods. The materials were synthesised by the sol–gel procedure from a mixture of zirconium(IV) tert-butoxide and tetraethyl orthosilicate. The final products were obtained after drying at 125°C followed by calcination at 400°C. The porous structures of the substrates were found to depend on their composition: at low zirconia contents these were formed by slit cavities while at high ZrO 2 concentrations the void structure became open; both cavities and necks were of similar size. In the first case, the pore size distribution function could be obtained from an analysis of the ascending boundary curve of the N 2 isotherm since adsorption occurred on a flat surface. In the second case, a unique pore-size distribution was obtained either from the ascending or descending boundary curves of the N 2 isotherm. A tubular geometry seemed appropriate for the description of the sorption characteristics of these substrates. Primary descending scanning curves traced within the hysteresis loops of samples having high ZrO 2 contents offered further textural information. X-Ray diffraction methods provided compound identification, evidence of phase segregation between ZrO 2 and SiO 2 , and particle and pore-size distributions

Formation of petroleum organic deposits on steel surfaces

An adhered organic deposit, formed within the petroleum well on the steel surface of the tubing walls, was systematically characterized following a sequence of bulk and surface techniques. The results allowed the identification of the tubing wall and its internal surface structures. As a consequence of the contact with sulphur-bearing compounds such as H2S and brine from petroleum, the pre-oxidized steel surface was modified by non-stoichiometric iron compound formation. These new iron phases favour adsorption and chemisorption of the petroleum polar compounds on the steel surface. Copyright  2002 John Wiley & Sons, Ltd

Efeito da classificação dos ovos sobre o rendimento de incubação e os pesos do pinto e do saco vitelino Effect of egg classification prior to setting on hatchability, embryonic mortality and chick and yolk sac weights

Dois experimentos foram realizados para avaliar, no primeiro, o efeito da idade da matriz sobre a uniformidade do peso de 1080 ovos e gemas e, no segundo, a influência da classificação de 9260 ovos sobre a eclodibilidade, a mortalidade embrionária e os pesos, absoluto e relativo, do pinto e do saco vitelino. Os tratamentos do experimento I foram ovos das matrizes com 31 (M31), 38 (M38) e 43 (M43) semanas de idade. No segundo, os ovos das matrizes com 31, 38 e 43 semanas foram distribuídos em seis tratamentos; A: ovos com pesos entre 66 e 72g, 33,3% deles originados de matrizes com diferentes idades; B: ovos com pesos entre 58 e 65g, 33,3% deles originados de matrizes com diferentes idades; C: ovos com pesos entre 52 e 57g, 33,3% deles originados de matrizes com diferentes idades; D: ovos com pesos entre 52 e 72g, produzidos por matrizes com 31 semanas; E: ovos com pesos entre 52 e 72g, produzidos por matrizes com 38 semanas; e F: ovos com pesos entre 52 e 72g, produzidos por matrizes com 43 semanas. As aves de M31 produziram ovos com pesos do ovo e da gema mais uniformes que as do M43. Ovos do tratamento A apresentaram a pior eclosão e a maior mortalidade embrionária após 15 dias de incubação, e produziram pintos com maiores pesos absoluto e relativo do saco vitelino.<br>Two experiments were carried out to study the effects of broiler breeder age on weight uniformity of 1,080 eggs and yolks, and the effects of 9,216 eggs classified prior to setting on hatchability, embryonic mortality, and the relationship between chick and yolk sac weights. In the first study, the three treatments were eggs from broiler breeders on 31st (M31), 38th (M38), and 43th (M43)-week of age. In the second study, eggs produced by three broiler breeders flocks (31st, 38th, and 43th wk of age) were divided in six treatments; A: eggs weighting from 66 to 72g, 33,3% of them produced by broiler breeders of different ages; B: eggs weighting from 58 to 65g, 33,3% of them produced by broiler breeders of different ages; C: eggs weighting from 52 to 57g, 33,3% of them produced by broiler breeders of different ages; D: eggs from 31-wk-old broiler breeders, weighting from 52 to 72g; E: eggs from 38-wk-old broiler breeders, weighting from 52 to 72g; F: eggs from 43-wk- old broiler breeders weighting from 52 to 72g. Eggs produced by M31 had egg and yolk weights more uniform than the eggs collected from M43. Treatment A had the worst hatchability, higher embryonic mortality after 15 days of incubation, and produced heavier hatched chicks with superior absolute and relative weights of yolk sac