ITSTUDIES ON THE EFFECT OF UREA ON THE COMPATIBILITY OF PMMA/PVC MIXTURES IN DMF BY A DILUTE- SOLUTION VISCOMETRY METHOD

The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results show thatthe polymer mixtures are compatible in DMF solution in the absence of urea. The influence of urea addition on the degree ofcompatibility of the polymer mixtures has been studied in terms of the compatibility parameters (△b_m and △[η]_m). It wasfound that the compatibility of the polymer mixtures is decreased with increasing urea addition, passing through a minimumat 0.5 M urea.     

Synthesis and Characterization of O,O-Dialkyl and Alkylene Dithiophosphoric Acid Adducts of Diphenyl Diselenide

Diphenyl diselenide reacts with O,O-dialkyl and alkylene dithiophosphoric acids in equimolar amounts in refluxing benzene to yield Ph 2 Se 2 HS 2 P(OR) 2 , R = Et, Pr-n, Pr-i, Bu-i and Ph, and Ph 2 Se 2 HS 2 POGO where G = CH 2 CMe 2 CH 2 m , --CH 2 CEt 2 CH 2 m , and --CMe 2 CMe 2 m . The complexes are sticky solids, soluble in common organic solvents and monomeric in nature. These have been characterized on the basis of elemental analysis, molecular weight determinations, UV, IR, and NMR ( 1 H, 13 C, and 31 P NMR). Spectral data reveal addition of dithiophosphate moieties to Ph 2 Se 2 .     

Kontsevich and Takhtajan Construction of Star Product on the Poisson–Lie Group GL(2)

Comparing the star product defined by Takhtajan on the Poisson–Lie group GL(2) and any star product calculated from the Kontsevich's graphs (any K-star product) on the same group, we show, by direct computation, that the Takhtajan star product on GL(2) can't be written as a K-star product.     

Novel monofunctional and bifunctional boronic acid‐functionalized squarylium dyes as precolumn and on‐column labels for protein analysis by capillary electrophoresis with laser‐induced fluorescence

This article presents a continuous capillary electrophoresis with laser‐induced fluorescence (CE‐LIF) following spectral studies of the noncovalent interactions between novel Squarylium Boronic Acid 4 (SQ‐BA4) & Squarylium Diboronic Acid 2 (SQ‐DBA2) squarylium dyes and human serum albumin (HSA). Two protocols were used wherein the on‐column‐labeling protocol was found to be more sensitive than the precolumn one by showing a better enhancement in the peak area of the HSA–dye complex besides lower limits of detection (LODs) for HSA. Also, stability studies were conducted with or without HSA using precolumn‐labeling mode over one week exhibiting the superiority of SQ‐BA4 to SQ‐DBA2. Then, a mixture containing three model proteins, HSA, β‐lactoglobulin B, and transferrin, was labeled on‐column with both dyes and completely resolved by CE‐LIF after optimization of several parameters. Both dyes provided lower LODs for HSA than those of β‐lactoglobulin B and transferrin with higher sensitivities. In addition, the SQ‐BA4 dye showed again greater sensitivities with all the three proteins than SQ‐DBA2.     

Selective behaviour of hyperfiltration cellulose acetate membranes: Part II. Streaming potential

Streaming potentials have been measured by the fast pulse method for cellulose acetate membranes cured at 85 and 95°C. Bounding, solutions of Li⁺, Na⁺, K⁺, Cs⁺, Mg²⁺, Sr²⁺, Ba²⁺ and La³⁺ chlorides were used in the concentration of 10^?4-10^?1M. The streaming potenial was shown to depend on the nature of the cation and to increase with decreasing solution concentration.Rather good consistency was obtained in dilute solutions between the electroosmotic cross coefficients calculated from the streaming potentials and from the electroosmosis measurements for Part I (M.G.A. Khedr, S.M. Abd el Haleem and A. Baraka, J. Electronal. Chem. 182 (1985) 157), according to the Onsager reciprocal relations. The deviation observed at higher concentrations, independent of the cation nature, is attributed to concentration polarization and/or excessive water transport encountered in electroosmosis measurements.Determination of additional phenomenological coefficients of the same system, the hydraulic permeability and the electric resistance enabled the estimation of the effective exchange capacity of modified cellulose acetate membranes. The resulting value of 2.1×10^?3 mol of unit charge/1 of pore liquid is compared to the corresponding values previously reported on a different basis.     

Effect of the nature of organic solvents on their interaction with metal halides

The radioactive tracer technique was used for studying the extraction and predicting the best conditions of separation of arsenic halides by organic solvents of different nature. Sulphuric acid was found to enhance the extraction of arsenic halides. Extraction of AsI₃ increases in the order cyclohexane <CCL₄ toluene <o-xylene <CHCl₄ and is quantitative by benzene and nitrobenzene. For a given extraction increases in the order AsCl₃<AsBr₃< <AsI₃. Spectral measurements were made on some solvents; at maximum absorption there was a linearity between absorbance and AsI₃ concentration up to 2·10⁻⁴ M for o-xylene and to 2.5·10⁻⁴ M for nitrobenzene.     

VISCOMETRIC STUDY OF POLY(METHYL METHACRYLATE) AND POLYSTYRENE BLENDS IN DIFFERENT SOLVENTS

The intermolecular interaction between poly(methyl methacrylate) (PMMA) and polystyrene (PS) intetrahydrofuran (THF) and N,N'-dimethyl formamide (DMF) solvents was studied at 28℃ using a dilute solution viscometrymethod. Solvent is believed to play a key role in characterizing the viscosity behavior of the polymer solution. The intrinsicviscosity and viscosity interaction parameter were experimentally measured for the binary (solvent/polymer) and for theternary systems in two solvents. The compatibility of the polymer mixture was discussed in terms of the sign of △b_m. Theresults show that the compatibility of PMMA/PS blend in DMF is larger than that in THF.     

Phenylpropanoids from the stem bark of Jacaranda mimosaefolia

Two new compounds: 2-(3',4'-dihydroxyphenyl) ethyl-3-O-α-L-rhamnopyranosyl-4-O-p-hydroxyphenylacetyl-6-O-caffeoyl-β-D-glucopyranoside and 2-(3',4'-dihydroxyphenyl) ethyl-3-O-α-L-rhamnopyranosyl-4-O-piperidine-3-carboxylic acid-6-O-caffeoyl-β-D-glucopyranoside were isolated from the stem bark of Jacaranda mimosaefolia. In addition, the known compounds lupeol, betulinaldehyde, terminic acid, betulinic acid, maslinic acid, β-sitosterol glucoside and isoacteoside were isolated and identified.     

Nineteen-membered pentaazamacrocyclic complexes bearing tetraamide groups

A new series of CoII, NiII, CuII and ZnII complexes incorporating pentaazamacrocyclic ligands has been prepared via the template condensation of o-aminobenzoic acid with succinic or phthalic acids in the presence of diethylenetriamine. The overall geometry and mode of bonding have been deduced on the basis of elemental analyses, i.r., 1H-n.m.r., e.p.r. and u.v.-vis. spectral studies, and conductivity and magnetic susceptibility measurements. An octahedral geometry is proposed for all the complexes, where five coordination sites are occupied by the macrocyclic nitrogens and the sixth by an anion.     

Comparative evaluation of xerogel-based activated carbons synthesized from aliphatic aldehydes of different chain lengths

This work deals with examining the performance of xerogel-based activated carbons (XACs), which were synthesized from aliphatic aldehydes of different carbon chain lengths. These XACs were compared with those synthesized from commonly synthesized XACs. The performance of the new xerogels was determined by examining the thermo-gravimetric analysis (TGA) and Fourier transform infrared (FTIR); however, the XACs were studied using infrared spectra (IR), scanning electron microscopy (SEM), and their adsorption capacities in gas and aqueous media (nitrogen adsorption, iodine number, adsorption of phenol and methylene blue, MB). The adsorption behavior of these investigated XACs to MB was studied in detail, using the Langmuir and Freundlich adsorption equations, in addition to kinetic (Lagergren first-order and pseudo-second-order) and thermodynamic models. The results show that long -chain aldehydes have a significant effect on increasing the total pore volume (V_T). Glutaraldehyde-based carbon xerogel is recommended as an economically superior adsorbent with an S_BET x yield of 571.9 m²/g. XACs from glutaraldehyde and propionaldehyde have higher surface area than commonly synthesized ACs from formaldehyde (F), Phenol/F, Tanin/F-, Polybenzooxazine/F, and Pyrogallol/F. The best models used for MB adsorption onto XACs are Langmuir and pseudo-second-order kinetic equations. The negative values of thermodynamic parameter ΔGº and positive values of ΔHº indicate the MB adsorption process is spontaneous and endothermic.