Solid-state interactions and drug release of teicoplanin in binary combinations with peracetylated α-, β-, and γ-cyclodextrins

Triacetyl α-cyclodextrin, triacetyl β-cyclodextrin and triacetyl γ-cyclodextrin were tested as possible hydrophobic carriers to prolong the release of hydrophilic teicoplanin (TCP). Physical–chemical characterization of individual components, drug-carrier physical mixtures at 0.5, 0.67 and 0.75 mass fraction of carrier, and the respective interaction products by kneading or evaporative crystallization under microwave irradiation was carried out using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In vitro drug release in pH 7.4 phosphate buffer at 37 °C was determined by intrinsic dissolution rate (IDR) measurements on non disintegrating compressed discs. Solid-state interactions of TCP with triacetyl α-cyclodextrin by evaporative crystallization and kneading and with triacetyl β-cyclodextrin by evaporative crystallization (probably resulting in carrier amorphization) were demonstrated. The role of carrier hydrophobicity, carrier mass fraction and preparation method of solid drug-carrier combinations on solid-state drug-carrier interactions and slowing down of TCP release was assessed. Modulation of drug release can be achieved using TCP-triacetyl γ-cyclodextrin combinations at 0.5 mass fraction of carrier.     

Solvent and temperature effects on the fluorescence and competitive photoreactions of cis-9-styrylanthracene

A fluorimetric and photochemical study of cis-9-styrylanthracene as a function of temperature has been carried out in different solvents with the aim of answering some open questions about the behavior of its first excited singlet state, S₁. In non-polar solvents, a parallel photoreactive pathway, leading to a cyclization adduct, was found to compete with fluorescence and isomerization already at 200 K, its contribution increasing markedly with temperature. The cis » trans photoisomerization occurs prevalently by a triplet mechanism, a detectable contribution of diabatic and adiabatic isomerization in S₁ being operative in these solvents from room temperature upwards. In polar solvents, the main deactivation pathway competitive with fluorescence is isomerization to trans, which occurs prevalently through a mixed singlet mechanism with a major diabatic and a minor adiabatic components.     

Oxidation of Cyclohexane by Molecular Oxygen Photoassisted by meso-Tetraarylporphyrin Iron(III)-Hydroxo Complexes

The photochemical and photocatalytic properties of iron meso-tetraarylporphyrins bearing an OH(-) axial ligand and different substituents in the beta-positions of the porphyrin ring are reported. Irradiation (lambda = 365 nm) in the absence of dioxygen leads to the reduction of Fe(III) to Fe(II) with the formation of OH(*) radicals. Substituents at the pyrrole beta-positions are found to markedly affect the photoreduction quantum yields. Under aerobic conditions, this photoreaction can induce the subsequent oxidation of cyclohexane to cyclohexanone and cyclohexanol by O(2) itself. The process occurs under mild conditions (22 degrees C; 760 Torr of O(2)) and without the consumption of a reducing agent. The polarity of the solvent and the nature of the porphyrin ring have a remarkable effect on the selectivity of the photooxidation process, likely controlling the cleavage of O-O bonds of possible iron peroxoalkyl intermediates. In particular, in pure cyclohexane, oxidation occurs with the selective formation of cyclohexanone; in contrast, in dichloromethane/cyclohexane mixed solvent, the main oxidation product is cyclohexanol. Phenyl-tert-butylnitrone (pbn) has been found to quench the radical chain autooxidation of the substrate thus increasing the yield of cyclohexanol. This becomes the only oxidation product when iron 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin hydroxide (Fe(III)(TDCPP)(OH)) is used as photocatalyst.     

Template evaporation method for controlling anatase nanocrystal size in ordered macroporous TiO2

The importance of pure-phase titanium oxide materials as catalysts, sensors, and photonic band-gap materials has been growing steadily. Recently, more attention has been focused on nanostructured titanium oxide showing controlled and periodic porosity on a nanometric scale. The nanocrystal size control of porous nanostructured titanium oxide in an anatase form is a crucial step for the organic template method. Simple template removal by evaporation in an inert atmosphere is reported in this article and compared with the calcination technique usually reported in the literature. The proposed method allows the formation of a double-porous (macro and meso) anatase phase. We demonstrate that it highly preserves the macropore order into a titanium oxide material and induces narrowly dispersed mesopores by controlling the nano-crystal size that is kept around 6 nm. For the proposed method, polystyrene beads are particularly suitable as templates, being evaporated in the temperature range of anatase existence. The final high surface area makes the materials appealing for applications as photocatalysts or sensors.     

Conservative restoration of the Augustus Arch of Fano: cleaning methodology as derived from preparatory analyses and sampling

The original appearance of Augustus Arch of Fano was compromised by a diffuse distribution of black scales and other deposits. In order to preserve the stone surface the restoration intervention operated with different cleaning techniques so that it was possible to use every method with a properly and not dangerous intensity. In particular it showed the possibility to use laser cleaning to destroy the external hard part of black scales, and complete the intervention with light chemical cleaning. In the case of Augustus Arch this way resulted useful for preserve signs on surface and cleaning every kind of deposits at the same time. Every intervention on such an important monument need to obtain at the same time the best result for materials conservation and the aim of image restore.     

Isotope dilution determination of polycyclic aromatic hydrocarbons in olive pomace oil by gas chromatography-mass spectrometry

A gas chromatographic (GC) method with mass spectrometry detection (MS) for the determination of eight polycyclic aromatic hydrocarbons (PAHs) in olive pomace oil has been developed. The oil was diluted with n-pentane and extracted by liquid-liquid partition with dimethyl sulphoxide (DMSO). After water addition and back-extraction with cyclohexane, a thin-layer chromatography on silica gel was performed as a further purification step. The PAHs spot was scraped off from the plate and the final extract was concentrated and analysed by GC-MS in full scan mode. The eight PAHs under investigation were determined in the presence of the corresponding labelled compounds added as internal standards to the sample at the beginning of the analytical process. The identified PAHs were then quantified by the isotope dilution methodology assuring the compensation of the concentration of each analyte for any variation in the sample preparation. The method precision was satisfactory with relative standard deviation (R.S.D.) values in the range 3.6-12.7% for all PAHs. The average recovery rates ranged from 69.0 to 97.5%. Accuracy was also calculated for benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene and benzo[ghi]perylene by analysing a certified reference material (CRM 458, coconut oil) with adequate results. All response curves exhibited a linear fit from 0.1 to 10 microg ml(-1) and the determination coefficients R2 were better than 0.9942. The limits of detection (0.1-0.4 microg kg(-1)) were acceptable when compared with the maximum permitted limit of 2 microg kg(-1) for each of the eight considered PAHs and 5 microg kg(-1) for the sum of the eight PAHs established by the Italian legislation. Measurement uncertainty was finally calculated identifying and quantifying the uncertainty components of the analytical process. The relative expanded uncertainties (Uc), expressed as percent values were in the range 8.5-11.4% thus appropriate for residues quantification in the range of concentrations considered in the present study.     

Symmetries and asymmetries in classical and relativistic electrodynamics

By a comparison between Maxwell's electrodynamics classically interpreted (MT) and relativistic electrodynamics (RED), this paper discusses whether the asymmetries in MT mentioned by A. Einstein in his 1905 relativity paper are only of a conceptual nature or rather involve specific empirical claims. It is shown that in fact MT predicts strongly asymmetric behaviour for very simple interactions, and an analysis is made of the extent of the symmetry achieved by means of relativistic postulates. A low velocity experiment is suggested which could provide another test of the accuracy of RED with respect to MT.     

Electrolytic Oxidation of Thiocyanate and Selenocyanate Salts and the Photoelectrochemical Effect.

New photosensitive materials can be obtained by electrochemical oxidation of thiocyanate and selenocyanate salts. Using (K,Na)SCN eutectic melt, the formation of an electrodic deposit, with photoelectrochemical properties, has already been reported by us. To improve the photoelectrochemical characteristics of the deposit, futher investigations were carried out in the following sistems: selenocyanate ammoniate, KSCH-Acetamide eutectic mixture and KSCN ethylene carbonate solution:. Attempts to obtain a massive deposit in the ammoniate solution were unsuccessful due to ammonia oxidation. Measurements performed on the other KSCN systems show that temperature is a parameter of remarkable importance. In fact, lowering the temperature one obtains a decrease on formation of parathiocyanogen on behalf of the polytrithiocyanogen, the species that gives rise to the photoeffect.