Model for predicting the composition of copolyesters: Polymerization of terephthalic acid, 2,2′-oxydiethanol,and 2,2-dimethyl-1,3-propanediol

Copolyesters of two glycols and a dicarboxylic acid moiety are frequently made to obtain specific physical properties. In the synthesis of these polymers an excess of glycol is used in the ester-exchange reaction and then removed during the polycondensation reaction to form a high-molecular-weight product. A model has been developed to predict the final polymer composition. The derivation is based on equilibria of reaction species (free glycol, polymer chain ends, and ester links) and the relative vapor pressures of the two reacting glycols. Calculated results are compared with experimental results of poly(2,2′-oxydiethylene: 2,2-dimethyl-1,3-propylene terephthalate)s. There is good agreement between calculated and experimental compositions. The model can be used to calculate the glycol concentrations that must be used to make a specific polymer composition. This model should also be useful in the calculation of other mole ratios of glycol to dicarboxylic acid that will make the same composition.     

Picosecond transient absorption spectra and kinetics of salicylidenaniline

Using the picosecond time-resolved absorption spectroscopic technique, the transient absorption spectra of salicylidenamline have been investigated and the room-temperature kinetic data are presented. A possible mechanism of the formation of the photochromic products of salicylidenamlme is proposed.     

A novel method for the estimation of arsenic(V) in organic compounds

A novel method for the determination of arsenic(V) in organic compounds has been developed by reducing combined arsenic(V) to arsenic(III) in aqueous acetic acid medium with zinc dust. In some cases, addition of ethyl alcohol is necessary to dissolve the compound and to keep the arsenic(III) compound in solution. The arsenic(III) is titrated with iodine and the end-point is detected visually with starch as indicator or potentiometrically.     

A comparative investigation into the effect of chronic alcohol feeding on the myocardium of normotensive and hypertensive rats: an electrophoretic and biochemical study

We investigated whether the imposition of chronic alcohol in hypertension leads to greater biochemical and cellular abnormalities of the myocardium than those arising in normotension. Fifteen-week-old spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) rats were fed ethanol-containing diets for six weeks. Particular attention was focused on the composition of contractile proteins identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), fractional rate of protein synthesis, and synthesis rates relative to RNA (RNA activity) or DNA (cellular efficiency). In addition, myocardial enzymes and adenine nucleotides were measured. In both SHR and WKY rats chronic ethanol caused a general decrease in the contents of all nine contractile proteins with myosin heavy chain predominantly affected. Fractional rates of mixed (i.e., total) and myofibrillary proteins remained unaltered in both WKY rats and SHR, as were cellular efficiencies. The RNA activity was significantly reduced in ethanol-treated SHR but not in WKY rats. In ethanol-treated SHR, cardiac creatine kinase (CK) and malate dehydrogenase (MDH) activities were increased, AMP levels were elevated, whilst ATP levels and the energy charge were reduced. In WKY rats, the only significant change related to increased aspartate aminotransferase activities in response to alcohol feeding. Although there were only subtle differences between the response of the normotensive and hypertensive rats due to ethanol dosage, the reduced ATP levels and increased CK and MDH activities in SHR may reflect a greater susceptibility to ischaemic damage. Reduced contractile protein content, particularly myosin heavy chain, may contribute to contractile defects, a common feature of subclinical and clinical alcoholic cardiomyopathy.     

Chemistry of iron complexes. Part V. Electron spin resonance spectra of some iron(III) complexes and X-Ray diffraction (powder) data of iron(II) complexes employing tertiary phosphine/arsine oxides

Summary Electron spin resonance spectra (X-band, 9.3 GHz) of iron(III) chloride complexes with tri-p-tolylarsine oxide (T₃AO), methylenebis(diphenylphosphine oxide) (mdpo) and 1,4-tetramethylenebis(diphenylphosphine oxide) (tmdpo) support their structures as [Fe(L-L)₂Cl₂][FeCl₄] (L-L=mdpo or tmdpo) and [Fe(T₃AO)₂Cl₂(OH₂)₂][FeCl₄]2H₂O. The x-ray powder diffraction patterns of some iron(II) iodide complexes with mdpo, tmdpo, dmdpo, dmdao and tmdao [dmdpo-1,2-dimethylenebis(diphenylphosphine oxide); dmdao and tmdao are the arsine analogs of dmdpo and tmdpo] show that the complexes are crystalline but not isomorphous.     

Ligating properties of tertiary phosphine/arsine sulphides or selenides—VI. Addition compounds of zinc(II), cadmium(II) and mercury(II) with sulphides or selenides of triphenyl- and tri- -tolylphosphines and 1,3-trimethylenebis (diphenylphosphine)

Post-transition elements react with ligands, triphenylphosphine sulphide or selenide (Ph₃PS or Ph₃PSe), tri-p-tolylphosphine sulphide or selenide (T₃PS or T₃PSe) and 1,3-trimethylenebis-(diphenylphosphine sulphide or selenide) (PDPS or PDPSe) in suitable organic solvents forming complexes of compositions: MX₂. L(M = Zn, X = I, L = all except Ph₃PS: M = Cd, X = I, L = T₃PS, T₃PSe, M = Hg, L = T₃PSe, X = Cl, Br, I); ZnI₂·2Ph₃PS, Hg(NO₃)₂·2Ph₃PS, CdBr₂·3T₃PSe and 3Hg(NO₃)₂·4Ph₃PSe. All these have been characterized through elemental analyses, ir spectra (4000−200 cm⁻¹) and molar conductance (nitrobenzene). Complexes are essentially nonelectrolytes. Tetrahedral structures have been assigned to all except a 1 : 3 complex which has been assigned a bridged octahedral structure.     

Thiopegan derivatives—XXI A mechanism for the formation of 9:10 and 10:11 thiopegan derivatives

Reactions between -haloketones and o-carbethoxy phenyl thiourea have been discussed; a mechanism for the observed exclusive formation of 9:10-thiopega-2:10-diene-4-ones in the case of -haloalkaryl ketones has been advanced and a number of intermediates isolated in case of chloro acetone.     

Interaction of photons with some solutions

The linear attenuation coefficients in aqueous solutions of some chlorides and sulphates, viz. MgCl₂·6H₂O, CaCl₂, SrCl₂·6H₂O, BaCl₂·2H₂O, Na₂SO₄, K₂SO₄ and MgSO₄·7H₂O were determined at 81, 356, 511, 662, 1173 and 1332 keV by the γ-ray transmission method in a good geometry setup. From the precision measured densities of these solutions, mass attenuation coefficients were then obtained which varied systematically with the corresponding changes in the concentrations (g/cm³) of these solutions. A comparison between experimental and theoretical values of attenuation coefficients has shown that the study has potential application for the determination of attenuation coefficients of solid solutes from their solutions without obtaining them in pure crystalline form.     

Studies on 2,1 -benzisoxazoles and related heterocycles. Reaction of diazomethane with 6-nitro-2,1-benzisoxazoles and nitrobenzofurazan oxides

Some 7-melhyl-substituted-2,1-benzisoxazoles and cyclopropanobenzofurazan oxides are synthesized and characterized by their elemental and spectral analyses.