Analytical investigations of adornment pieces from Susani (Timiş County,Romania)

Journal of Thermal Analysis and Calorimetry - The samples originate from the funerary cache of a cremation burial mound dating from the Late Bronze Age (according to the Reinecke chronological...     

Phosphonate metal–organic frameworks used as dye removal materials from wastewaters

A very intense study class of complex porous materials, metal–organic frameworks (MOFs), composed of diverse central metallic ions attached to organic linkers, was used in this study as adsorbant materials from wastewaters. Phosphonate MOFs were prepared by the reaction of divalent inorganic salts (CoSO₄ · 7H₂O, NiSO₄ · 6H₂O, CuSO₄ · 5H₂O,) with vinyl phosphonic acid in hydrothermal conditions, obtaining cobalt, nickel, and copper vinylphosphonate (CoVP, NiVP, and CuVP). During synthesis the experimental conditions were varied in terms of time, temperature, and pH. The synthesized materials were characterized by Fourier transform infrared, thermogravimetric analysis, scanning electron microscopy, and X-ray crystallography. The efficiency of MOFs as adsorbents was investigated for diverse initial dye concentrations at different pH values and at three temperatures (25, 40, and 55°C). The synthesized materials presented good efficiency in the elimination of anionic as well as cationic type of dyes from aqueous solutions. The highest adsorption capacities were obtained working at optimum solution pH 4.2 for Acid Orange 7 and 10 for Basic Fuchsine, using 1 g/L of MOFs at room temperature (25°C). The adsorption capacities increase in the following order: CuVP < NiVP < CoVP.     

Natural rubber–based composites filled with bioglasses from a CaO‐SiO2‐P2O5‐Ag2O system. Effect of Ag2O concentration in the filler on composite properties

Bioactive glass was first synthesized by L. Hench in 1971. There are many studies on the properties of several metals and metal ions dopants used in the SiO₂‐CaO‐P₂O₅ system of bioglasses, such as Ag, Cu, Zn, and Fe. A number of authors have carried out research related to the influence of silver oxide on the properties of bioglasses . However, publications on the properties of elastomer‐based composites containing bioactive glasses are relatively scarce. We have not found in the literature studies discussing how silver oxide concentration in bioglasses of the CaO‐SiO₂‐P₂O₅‐Ag₂O system affects the significant properties of a natural rubber biocomposite. In this regard, the purpose of the present work is to investigate the aforementioned influence on the properties of this type of composites, namely, vulcanization, physicomechanical, thermal, dynamic, dielectric, electric, and thermoconductive characteristics. We have established those parameters of the composites to be impacted considerably by both degree of filling with bioglass and the silver oxide content in the latter. The improvement in the composites thermostability and some of their physicomechanical performance is the most significant. The volume resistance decreases, and the thermal conductivity coefficients increase. Results from scanning electron microscopy and energy‐dispersive X‐ray (EDX) analyses have confirmed the influence of silver oxide initially on the phase composition of the bioglass, hence on the properties of the biocomposites through changes in the bioglass used as filler. The dielectric characteristics of some of the biocomposites suggest that they can be used as substrates and insulating layers in flexible antennas for short‐range wireless communications.     

Physicochemical characterization and molecular modeling study of host–guest systems of aripiprazole and functionalized cyclodextrins

Journal of Thermal Analysis and Calorimetry - Aripiprazole (ARP), an innovative atypical antipsychotic drug, exhibits very low aqueous solubility, affecting its dissolution and absorption and high...     

Synthesis and thermal behavior of some diisocyanate–silane compounds

Some silica-organic compounds were prepared by an addition reaction between γ-amino-propyl-triethoxy silane and 4,4′-diphenylmethane diisocyanate. The obtained products were characterized by FTIR spectrometry. The essential synthesis parameter was the molar ratio between the two reactants. The thermal behavior of the products was rather good, until 150 °C no mass loss or thermal effects being observed. The thermal behavior was determined under non-isothermal conditions, using TG/DTG/HF diagrams. Due to the hydroxyl end-groups, these compounds are recommended for adhesives between organic and inorganic surfaces.     

Photochemical and Thermal Stability of Some Dihydroxyacetophenones Used as UV‐MALDI‐MS Matrices

2,4‐, 2,5‐, 2,6‐ and 3,5‐dihydroxyacetophenone (DHA) used as matrices in matrix‐assisted ultraviolet laser desorption/ionization mass spectrometry (UV‐MALDI‐MS) were studied by steady‐state and transient absorption spectroscopy, together with DFT calculations at the B3LYP level of theory. All compounds have low fluorescence quantum yields, possibly due to an efficient excited‐state intramolecular proton transfer (ESIPT). Laser flash photolysis (LFP) results showed that, only for 2,4‐DHA, a phototautomer could be detected at λ = 400 nm. Their photochemical stability in solution at different wavelengths and conditions was analyzed by UV–Vis and ¹H nuclear magnetic resonance spectroscopy (¹H‐NMR), together with thin layer chromatography and ultraviolet laser desorption/ionization mass spectrometry (UV‐LDI‐MS). Only 3,5‐DHA showed decomposition when irradiated, probably because phototautomerization is not possible. Thermal stability studies of these compounds in solid state were also conducted.