The P43 enanti-omorph of Sr2As2O7.

The crystal structure of strontium diarsenate has been reinvestigated from single-crystal X-ray diffraction data. In contrast to the previous determinations of this structure [Weil et al. (2009 ▶). Solid State Sci. 11, 2111-2117; Edhokkar et al. (2012 ▶). Mater. Sci. Eng., 28, 012017] and to all isotypic A 2 B 2O7 compounds that crystallize in the space group P41, the current redetermination revealed the P43 enanti-omorph of Sr2As2O7 with a purity of 96.3 (8)%. The crystal structure is made up from two eclipsed As2O7 diarsenate groups (symmetry 1) with characteristically longer As-O bridging bonds [1.756 (4)-1.781 (4) Å] than the terminal As-O bonds [1.636 (4)-1.679 (4) Å] and four Sr(2+) sites with coordination numbers ranging from seven to nine. The building units are arranged in sheets parallel to (001).

Lutetium(III) cyclo-tetra-phosphate.

Single crystals of the title compound, tetra-lutetium(III) tris-(cyclo-tetra-phosphate), Lu(4)(P(4)O(12))(3), were obtained by solid-state reaction. The cubic structure is isotypic with its Al(III) and Sc(III) analogues and is built up from four-membered (P(4)O(12))(4-) phosphate ring anions ( symmetry), isolated from each other and further linked through isolated LuO(6) octa-hedra (.3. symmetry) via corner sharing. Each LuO(6) octa-hedron is linked to six (P(4)O(12))(4-) rings, while each (P(4)O(12))(4-) ring is linked to eight LuO(6) octa-hedra.

Aluminium cyclo-hexa-phosphate.

Single crystals of the title compound, Al(2)P(6)O(18), were obtained by solid-state reaction. The monoclinic structure is isotypic with its Cr(III), Ga(III) and Ru(III) analogues and is built up of six-membered phosphate ring anions, P(6)O(18) (6-), isolated from each other and further linked by isolated AlO(6) octa-hedra by sharing corners. Each AlO(6) octa-hedron is linked to four P(6)O(18) (6-) rings. More accurately, two rings are linked through bidentate diphosphate groups attached in the cis-positions to the AlO(6) octa-hedron. The other two rings are linked to the two remaining corners, also in cis-positions of the AlO(6) octa-hedron.

Photocatalytic degradation of methylene blue dye in aqueous solution by MnTiO3 nanoparticles under sunlight irradiation.

Nanophotocatalyst MnTiO3 powders were synthesized by sol-gel technique and characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), as well as their thermal behavior has been studied by differential thermal and thermogravimetric analyses (DTA/TGA). Powders morphology was analyzed by means of Transmission electron microscopy (TEM). Effect of various process parameters like amount of photocatalyst, dye concentration, solution pH and irradiation time on the extent of removal of dye were studied in detail. The photo-degradation was relatively higher using lower amount (0.005 g) of semiconductor, reached rate of 75% and 70% after 240 min for mixed MnTiO3/TiO2 and pure MnTiO3 nanocatalysts. The kinetic model of photocatalytic degradation of MB follows pseudo-first-order kinetic with a high correlation coefficient values (R2 > 0.95). These results underline the use of effective, low-cost and easily available MnTiO3 photocatalyst for the decomposition of pollutants to water under natural sunlight.

An ortho-rhom-bic polymorph of the ultraphosphate YP(5)O(14).

Single crystals of yttrium penta-phosphate(V), YP(5)O(14), were obtained by solid-state reaction. The ortho-rhom-bic title compound belongs to the family of ultraphosphates and is the second polymorph of this composition. It is isotypic with its Ho and Er analogues. The structure contains two bridging Q(2)-type PO(4) tetra-hedra and one branching Q(3)-type PO(4) tetra-hedron, leading to infinite ultraphosphate ribbons running along the a axis. The coordination polyhedron around the Y(3+) cation may be described as distorted bicapped trigonal-prismatic. The YO(8) polyhedra are isolated from each other. They are linked by corner-sharing to the O atoms of six Q(2)-type and of two Q(3)-type PO(4) tetra-hedra into a three-dimensional framework.

Gelatin based bio-films prepared from grey triggerfish' skin influenced by enzymatic pretreatment.

Gelatins from grey triggerfish skin were extracted with different methods. The treatment by pepsin (PG) improved the yield of extraction when compared with untreated gelatin (UG) and acidic gelatin (AG). The outputs of gelatins AG, UG and PG, obtained respectively, with acitic acid, glycine buffer and glycine buffer added with 5U of pepsin/g of the skin beforehand treated by alkali, were 6.9%, 7.9% and 9.7%, respectively. The enzymatic treatment of the alkali-pretreated skin of grey triggerfish altered the electrophoresis profile, biophysical, gellification, rheological and thermal properties of the prepared gelatins extracted under acidic condition. However, the untreated gelatin obtained without pepsin exhibited the highest transition and enthaply temperatures. In addition, the properties of the prepared films were interconnected to their microstructure as demonstrated by scanning electron microscopy. Furthermore, films with PG and UG had a regular surface and a more condensed structure, whereas films prepared with AG had rougher surface.

Physical, structural, antioxidant and antimicrobial properties of gelatin-chitosan composite edible films.

Physico-chemical and mechanical properties of cuttlefish skin gelatin (G), chitosan (C) from shrimp (Penaeus kerathurus) and composite films (G75/C25, G50/C50, G25/C75) plasticized with glycerol were investigated. The results indicated that chitosan film had higher tensile strength and lower elongation at break when compared with the other films. Composite films show no significant difference in tensile strength (TS), thickness and transparency. The structural properties evaluated by FTIR and DSC showed total miscibility between both polymers. DSC scans showed that the increase of chitosan content in the composite films increases the transition temperature (Tg) and enthalpy (ΔHg) of films. The morphology study of gelatin, chitosan and composite films showed a compact and homogenous structure. In addition, gelatin and G75/C25 films demonstrated a high antioxidant activities monitored by ß-carotene bleaching, DPPH radical-scavenging and reducing power activities, while films contained chitosan exhibited higher antimicrobial activity against Gram-positive than Gram-negative bacteria.

Comparative study of physico-mechanical and antioxidant properties of edible gelatin films from the skin of cuttlefish.

Physicochemical properties of edible films based on cuttlefish skin gelatin extracted without (G0) or with different concentrations of pepsins (5 (G5), 10 (G10) and 15 (G15) U/g of skin) were investigated. Edible films prepared with partially hydrolyzed gelatins had lower tensile strength (TS) and elongation at break (EAB), but higher water vapour permeability (WVP) and water solubility than the control film. FTIR spectra of obtained gelatin films revealed a significant loss of molecular order of the triple helix. In addition, differential scanning calorimetric (DSC) analysis indicated that partially hydrolyzed gelatine films exhibited lower transition temperature and enthalpy compared with those of control film. The properties of the films were related to their microstructure, which was observed by scanning electron microscopy. Films with G0 and G5 had a smooth surface and a more compact structure, while films prepared with G10 and G15 had coarser surface. Thus, the chain length of extracted gelatin directly affected the properties of corresponding films.