Zeolitic inorganic–organic polymer electrolytes: a material based on poly(ethylene glycol) 600, SnCl4 and K4Fe(CN)6

This report describes the synthesis of a new zeolitic inorganic–organic polymer electrolyte with the formula [Fe_xSn_y(CN)_zCl_v(C_2nH_4n+2O_n+1)K₁]. This material is based on poly(ethylene glycol) 600, SnCl₄ and K₄[Fe(CN)₆], and is obtained via a sol→gel transition. Mid and far Fourie than form infrared (FT‐IR) studies, analytical data and X‐ray Photoelectron spectroscopy (XPS) investigations allowed us to conclude that this material is a mixed inorganic–organic network in which Fe and Sn are bonded by CN bridges and tin atoms by PEG 600 bridges. Mid‐infrared (MIR) FT‐IR investigations demonstrated that the polyether chains assume a conformation of the TGT (T = trans, G = gauche) type. Micrographs of the compound obtained by scanning electron microscopy reveal that its morphology resembles a smooth gummy paste. The conductivity of the material at different temperatures was determined by impedance spectroscopy (IS). Results indicated that the material conducts ionically and that its conductivity is strongly influenced by segmental motion of the polymer network. Finally, this network shows a conductivity of ca. 3.7 × 10⁻⁵ S/cm at 25 °C. Copyright © 2000 John Wiley & Sons, Ltd.     

Stabilisation Effect of Calcium Ions on Polymer Network in Hydrogels Derived from a Lyotropic Phase of Hydroxypropylcellulose

The process of crosslinking of the hydrogel, derived from lyotropic liquid crystalline (LLC) phases of hydroxypropylcellulose/acrylic acid-water, by calcium ions was studied by means of Raman and dielectric spectroscopy. Formation of salt by poly(acrylic acid) and calcium ions, resulting in hydrogel crosslinking, induces differences in Raman spectra of the hydrogel before and after the crosslinking. The crosslinking results in significant increase in the activation energy of β-relaxation of poly(acrylic acid). This is a direct consequence of restriction in motions of carboxylic groups of poly(acrylic acid) due to calcium salt formation. Thus, the crosslinking improves polymer network stability in the hydrogel in the swollen state.     

Modification of propylene-ethylene copolymers by reactive extrusion

The rheological properties of commercial propylene-ethylene copolymers were modified by reactive extrusion. A dialkyl peroxide was used as initiator of the controlled degradation reaction of the starting polymers. The experiments were carried out in a twin screw extruder at different peroxide concentrations, temperatures, and screw speeds. Gel permeation chromatography was used to estimate the molecular weight distribution of the original and modified copolymers. It has been observed that the estimated molecular weight of the copolymers tends to decrease with the increase in peroxide concentration at all extrusion conditions studied. The linear viscoelastic properties of all the polymers were evaluated at different temperatures and frequencies in a rotational rheometer. Both the viscous and the elastic properties decrease with augmenting peroxide concentration. The Theological behavior of the materials is strongly affected by the global ethylene content of the copolymers. The scanning electron microscopy study did not reveal a significant difference between the morphology of the unmodified and the modified blends for a given composition of the original copolymers. In all the cases the microstructure is composed of a finely dispersed phase of ethylene-propylene copolymer within a continuous polypropylene phase.     

Analytical procedure for the determination of chlorobenzenes in sediments

This study presents the procedure for the determination of chlorobenzenes in sediment. It consists of solvent extraction (shaking overnight), extract clean-up with the use of a homemade glass column packed with activated silica gel and freshly activated copper, and slow solvent evaporation to a volume of 0.3 mL. Two-microliter extract portions are analyzed by means of gas chromatography with an Rtx-624 capillary column (60 m x 0.32 mm, d(f) = 1.8 microm) coupled with mass spectrometry (in selected ion-monitoring mode). Deuterated 1,2-dibromobenzene is used as the recovery standard. The recovery of this method for all chlorobenzenes is high (ranging from 78% to 107%) with the exception of monochlorobenzene, which is 58%. The method is also characterized by good precision, which is commonly accepted in the analysis of trace organic pollution.     

A study of the chemical forms or species of manganese found in coal fly ash and soil

The chemical speciation of manganese of environmental and toxicological interest was undertaken in coal fly ash and soil. Hard coal used in combustion creates considerable quantities of waste ash. The greatest quantities of industrial ashes are stored in the form of waste-heaps, which create a serious problem as the source of inorganic pollution. It is necessary to identify physical and chemical properties of ash, especially when analyzing the pollution of soil by trace metals, which are potentially mobile in environment. In this work, a new analytical method has been developed and used successfully for identification and determination of chemical forms of manganese in coal fly ash and soil. The basic chemical forms of metals contained in the environmental samples (fly ash and soil) can be described by using sequential extraction method. To identify Mn ions, the UV-VIS spectrophotometric method was used by means of comparative analysis of spectrophotometric spectra of appropriate Mn ions in the standard solutions and solutions obtained after extraction. The concentration of manganese in all solutions was determined by the Flame Atomic Absorption method. The experimental approach and analytical method developed in this study appear adequate for this purpose and can therefore be used for similar research.     

Psoralen derivatives and longwave ultraviolet irradiation are active in vitro against human melanoma cell line

Cutaneous malignant melanoma is a very serious form of skin cancer that arises from melanocytes. Currently there is no effective treatment for metastatic melanoma so intense clinical trials are evaluating new drugs for this human malignancy. Psoralens are a group of compounds that bind to DNA in rapidly dividing cells and with ultraviolet light in the A band (UVA) cause DNA crosslinking, thereby preventing cellular division. They are used in the treatment of psoriasis and cutaneous T-cell lymphoma among other skin and blood diseases. We have investigated the cytotoxic potential of three psoralen derivatives plus UVA exposure (PUVA) on a established cell line of human melanoma. Cells were treated with different concentrations of 8-methoxypsoralen (8-MOP), 4,5',8-trimethylpsoralen (TMP) and 7-methylpyridopsoralen (MPP), for 1 h and after exposure to UVA light (0.3 J/cm(2)) were allowed to recover over a 24-72 h period. Viability was assessed by the microculture 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. Cisplatin, one of the most important drugs in the chemotherapy of melanoma, was included for comparative studies. All the psoralen derivatives tested were markedly cytotoxic in a dose and post-exposure-time dependent manner. The IC(50) values for 72 h of post-exposure time were as follows: MPP=0.05+/-0.01, TMP=0.13+/-0.003 and 8-MOP=10.79+/-1.85 micromol/L. Regardless of the limitations of the in vitro model, our results suggested that the lower IC(50) values of TMP and MPP might be of clinical importance.     

Eigenvalue asymptotics for a class of md-elliptic ψdo’s on manifolds with cylindrical exits

We obtain a Weyl formula for a class of positive md-elliptic operators on manifolds with finitely many cylindrical exits. Weyl formula is deduced by a classical Tauberian theorem through the asymptotic expansion at t=0 of the trace of the heat parametrix. The constant of the leading term is expressed invariantly by means of the usual principal symbol and exit symbols. Received: February 14, 2000?Published online: June 11, 2002     

Oxidation of alkanes and alcohols with hydrogen peroxide catalyzed by complex Os3(CO)10(µ‐H)2

Trinuclear carbonyl hydride cluster, Os₃(CO)₁₀(µ‐H)₂, catalyzes oxidation of cyclooctane to cyclooctyl hydroperoxide by hydrogen peroxide in acetonitrile solution. The hydroperoxide partly decomposes in the course of the reaction to afford cyclooctanone and cyclooctanol. Selectivity parameters obtained in oxidations of various linear and branched alkanes as well as kinetic features of the reaction indicated that the alkane oxidation occurs with the participation of hydroxyl radicals. A similar mechanism operates in transformation of benzene into phenol and styrene into benzaldehyde. The system also oxidizes 1‐phenylethanol to acetophenone. The kinetic study led to a conclusion that oxidation of alcohols does not involve hydroxyl radicals as main oxidizing species and apparently proceeds with the participation of osmyl species, ‘Os?O’. Copyright © 2010 John Wiley & Sons, Ltd.     

trans-2-Aminocyclohexanols as pH-triggers for conformationally controlled crowns and podands

Protonation of trans-2-aminocyclohexanols leads to dramatic conformational changes: due to an intramolecular hydrogen bond a conformer with equatorial position of ammonio- and hydroxy-groups becomes predominant. The trans-2-aminocyclohexanol moiety has been used for pH-induced conformational switching of a crown ether and a podand.     

Determination of free fatty acids in chocolate by liquid chromatography with tandem mass spectrometry

This paper describes a rapid extraction method, based on a matrix solid-phase dispersion technique using diatomaceous earth as solid support and 50:50 (v/v) chloroform/methanol as extracting solvent, that can determine 11 free fatty acids in chocolate. The extraction procedure is followed by reversed-phase liquid chromatography/tandem mass spectrometry (LC/MS/MS) using a normal-bore (4.6 mm i.d.) C-18 column and an electrospray interface operating in the negative ion mode. The tandem mass spectra of selected compounds show that charge-remote fragmentation (CRF) mechanisms are occurring; the intensities of the CRF reactions increase with the carbon number and degree of unsaturation of the fatty acids. Average recoveries, evaluated by the standard addition method, vary between 79-103%, and the estimated quantification limits are less than 153 ng/g. The proposed method has been used to analyse nine chocolate samples from various price ranges, bought from supermarkets.