Transesterification of Camelina sativa Oil Catalyzed by Mg/Al Mixed Oxides with Added Divalent Metals.

This paper is focused on the heterogeneously catalyzed transesterification (in a batch reactor) of vegetable oil, including the determination of leached metals. The oil was obtained from the short-season crop Camelina sativa. The reaction was catalyzed by mixed oxides, which were synthesized from Mg/Al hydrotalcites with built-in different types of divalent cations such as Mn, Ca, Co, Ni, and Fe. The various physicochemical properties like the structure by X-ray diffraction, acidity, basicity, and textural properties were measured and the effect of the added cation type on catalyst properties and activity was compared. A noticeable relationship between the cation type and catalytic activity in the transesterification reaction was observed. The highest ester content of 96.6 wt % after 7 h of transesterification was observed for catalysts with nickel and iron. The statistical analysis of results showed that the catalyst activity was mainly influenced by middle-temperature basic sites. The novelty lies in transesterification over five different heterogeneous catalysts-mixed oxides with added divalent metals at the same reaction conditions of C. sativa oil.

Beta-glucan and arabinogalactan-based xerogels for abuse-deterrent opioid formulations.

Novel polysaccharide hydrogels based on Methocel and beta-glucan or arabinogalactan and corresponding xerogels were prepared and described. Phase stability of hydrogels was confirmed over multiple freeze-thaw cycles. Binary beta-glucan:Methocel hydrogels showed the highest freeze-thaw stability in terms of their syneresis. The viscosity of binary hydrogels was further increased by adding water-soluble resin. Freeze drying of polysaccharide gels yields xerogels suitable as abuse-deterrent vehicles for opioid delivery. The xerogels were characterized by infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, scanning electron microscopy and by their swelling behavior. As a model opioid, tramadol hydrochloride formulations were prepared with various xerogel matrices and dissolution-release profiles were determined. The xerogel matrix acts as a functional excipient that forms a viscous gel barrier with decreased rate of tramadol release. Moreover, slower drug release with no dose dumping is observed in the presence of ethanol. The release kinetics demonstrated that hydrophilic gels with beta-glucan or arabinogalactan are effective for controlling and prolonging the drug release for 12 h which could reduce the required number of administrations.

Arabinogalactan:ß-glucan as novel biodegradable carriers for recombinant human thrombin.

The aim of this work was to evaluate the effects of incorporating thrombin in arabinogalactan (AG)/ß-glucan (BG)-based carriers. The products were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray powder diffraction (XRPD) and X-ray photoelectron spectroscopy techniques. Results, especially deconvoluted XRPD patterns indicated creation of new phases and potential complex formation. Results also highlighted that the AG carrier leads to higher residual thrombin-specific activity, while the in vivo haemostatic effect was enhanced when insoluble BG was present in the matrix. Our results confirm that thrombin can be successfully added to the carriers and that these materials are promising alternatives to standard vehicles.

Removal of pyridine from liquid and gas phase by copper forms of natural and synthetic zeolites.

Zeoadsorbents on the basis of copper forms of synthetic zeolite ZSM5 and natural zeolite of the clinoptilolite type (CT) have been studied taking into account their environmental application in removing harmful pyridine (py) from liquid and gas phase. Sorption of pyridine by copper forms of zeolites (Cu-ZSM5 and Cu-CT) has been studied by CHN, X-ray photoelectron spectroscopy, X-ray powder diffractometry, FTIR spectroscopy, thermal analysis (TG, DTA and DTG) and analysis of the surface areas and the pore volumes by low-temperature adsorption of nitrogen. The results of thermal analyses of Cu-ZSM5, Cu-(py)(x)ZSM5, Cu-CT and Cu-(py)(x)CT zeolitic products with different composition (x depends on the experimental conditions of sorption of pyridine) clearly confirmed their different thermal properties as well as the sorption of pyridine. In the zeolitic pyridine containing samples the main part of the pyridine release process occurs at considerably higher temperatures than is the boiling point of pyridine, which proves strong bond and irreversibility of py-zeolite interaction. FTIR spectra of Cu-(py)(x)zeolite samples showed well resolved bands of pyridine. The results of thermal analysis and FTIR spectroscopy are in a good agreement with the results of other used methods.

Ab initio structure determination of 5-anilinomethylene-2,2-dimethyl-1,3-dioxane-4,6-dione from laboratory powder data--a combined use of X-ray, molecular and solid-state DFT study.

The crystal structure of the title compound was solved from laboratory powder diffraction data in the triclinic group P\bar 1 by simulated annealing using the program DASH. Since Rietveld refinements yielded inaccurate geometries the structure was finally refined by geometry optimization using energy minimization in the solid state with the DFT/plane-waves approach. The molecule is essentially planar and its Meldrum's acid moiety (2,2-dimethyl-1,3-dioxane-4,6-dione) has a flattened boat conformation. The bond orders in the molecule estimated using a natural bond-orbitals formalism correlate with the optimized bond lengths. The structure in the solid state is based on dimer units in which the molecules are held by N-H...O and C-H...O hydrogen bonds in addition to electrostatic interactions. These units interact through weak C-H...O hydrogen bonds. It is suggested that structure refinement by energy minimization at the DFT level of theory may in many cases successfully replace Rietveld refinement.