Interplay between composition,structural dynamics and thermodynamic data in amino acid nitrates

Journal of Thermal Analysis and Calorimetry - A systematic thermodynamic study has been performed for a series of nitrates having cations derived from the α-amino acids glycine (Gly),...     

Integration and dimensional modeling approaches for complex data warehousing

With the broad development of the World Wide Web, various kinds of heterogeneous data (including multimedia data) are now available to decision support tasks. A data warehousing approach is often adopted to prepare data for relevant analysis. Data integration and dimensional modeling indeed allow the creation of appropriate analysis contexts. However, the existing data warehousing tools are well-suited to classical, numerical data. They cannot handle complex data. In our approach, we adapt the three main phases of the data warehousing process to complex data. In this paper, we particularly focus on two main steps in complex data warehousing. The first step is data integration. We define a generic UML model that helps representing a wide range of complex data, including their possible semantic properties. Complex data are then stored in XML documents generated by a piece of software we designed. The second important phase we address is the preparation of data for dimensional modeling. We propose an approach that exploits data mining techniques to assist users in building relevant dimensional models.     

Vesicle Origami: Cuboid Phospholipid Vesicles Formed by Template-Free Self-Assembly

Phospholipid liposomes are archetypical self-assembled structures. To minimize the surface tension, the vesicles typically are spherical. Deciphering the bilayer code, the basic physical interactions between phospholipids would allow these molecules to be utilized as building blocks for novel, non-spherical structures. A 1,2-diamidophospholipid is presented that self-assembles into a cuboid structure. Owing to intermolecular hydrogen bonding, the bilayer membranes form an exceptionally tight subgel packing, leading to a maximization of flat structural elements and a minimization of any edges. These conditions are optimized in the geometrical structure of a cube. Surprisingly, the lateral surface pressure in the membrane is only one third of the value typically assumed for a bilayer membrane, questioning a long-standing rule-of-thumb.     

The calorimetric study of some guanidine derivatives involved in living bodies nitrogen metabolism

The energies of combustion of creatine (anhydrous and monohydrate), creatinine, and arginine were measured in a static bomb adiabatic calorimeter, in pure oxygen at 3,040 kPa. The derived standard enthalpies of formation in solid state of the above-mentioned compounds are, respectively, −520.4 ± 4.3, −809.7 ± 1.3, −204.2 ± 7.0, and −634.8 ± 2.3 kJ mol⁻¹ . The data of enthalpy of formation are compared with literature values and with estimated values by means of group additivity. The dehydration of creatine monohydrate and the processes occurring in the three guanidine derivatives at temperatures exceeding 200 °C were investigated by means of DSC.     

Nanomaterials with antioxidant properties,obtained via biotechnology,using the solid state biosynthesis

ABSTRACT

Two nano materials type emulsion (EP and EM), that includes two different bioactive metabolites of Monascus sp. were obtained. Prior obtaining the nanoemulsion, tha enatural extracts, P (Monascus sp.1 – parental strain) and M (Monascus sp.2 - modified strain), were conditioned in order to increase their stability and biodisponibility. The new nanomaterials obtained were tested in terms of physical and chemical characteristics, by dynamic light scattering, infrared spectra and thermal analysis. Biological properties was investigated, by determining the effects of these new bio materials on wound healing and by measuring the antioxidant properties. The results obtained reveal the presence of aggregates with dimensions in the range of 1–100 nm, proving that these bioproducts are nano materials. The infrared spectra indicate the presence of benzene metadisubstituted (bands at 881.25 cm^?1 and 880.4 cm^?1 respectively), which are specific to Monascus metabolites Thermal analysis indicate the similarities between the matrix used in conditioning and the final nano products contains Monascus metabolites. The influence of these nano bio products on cicatrisation process was determined by tests on mices. It was concluded that there is small positive effect of the extracellular EP product. In this case, the bio product increase with 3% the rate of cicatrisation process, in comparison with the witness. All the two nano products show a significant antioxidant properties, with specific quenching rate of 97.7%     

Evaluation of manganese and oxygen content in La0.7Sr0.3MnO3−δ and correlation with the thermodynamic data

In order to understand how the thermodynamic properties are related to the oxygen and manganese content in the Sr-doped lanthanum manganites, nonstoichiometric perovskite phases La_0.7Sr_0.3MnO_3−δ have been investigated by using solid state electrochemical techniques, as well as wet chemical methods. The influence of the oxygen stoichiometry change on the thermodynamic properties was examined using the data obtained by a coulometric titration technique coupled with solid state electromotive force measurements (EMF). The results were correlated with the average Mn valence values as determined by a chemical method based on two independent iodometric titrations, with amperometric dead-stop end point detection. New features related to the relationship between the average Mn valence, the oxygen nonstoichiometry variation, and the thermodynamic behavior were evidenced.     

DSC investigation of nanocrystalline TiO<Subscript>2</Subscript> powder

The aim of the article is to investigate the influence of particle size on titanium dioxide phase transformations. Nanocrystalline titanium dioxide powder was obtained through a hydrothermal procedure in an aqueous media at high pressure (in the range 25–100 atm) and low temperature (≤200 °C). The as-prepared samples were characterized with respect to their composition by ICP (inductive coupled plasma), structure and morphology by XRD (X-ray diffraction), and TEM (transmission electron microscopy), thermal behavior by TG (thermogravimetry) coupled with DSC (differential scanning calorimetry). Thermal behavior of nanostructured TiO₂ was compared with three commercial TiO₂ samples. The sequence of brookite–anatase–rutile phase transformation in TiO₂ samples was investigated. The heat capacity of anatase and rutile in a large temperature range are reported.