Electrogenerated Fe(I) Porphyrins: Efficient Electrocatalysts for Reductive Dechlorination of DDT in N,N′‐Dimethylformamide

Two iron(I) porphyrins were electrogenerated and then utilized as catalysts for the reductive dechlorination of 1,1‐bis(4‐chlorophenyl)‐2,2,2‐trichloroethane (DDT) in N,N′‐dimethylformamide. No reaction is observed between DDT and the Fe(III) or Fe(II) forms of the porphyrin, but the electrogenerated Fe(I) porphyrin efficiently catalyzes the electroreduction of DDT to give (1,1‐bis(4‐chlorophenyl)‐2,2‐dichloroethane) DDD, (1,1‐bis(4‐chlorophenyl)‐2,2‐dichloroethylene) DDE and (1,1‐bis(4‐chlorophenyl)‐2‐dichloroethane) DDMU as determined by GC‐MS analysis. The reductive dechlorination was monitored by electrochemistry, controlled potential electrolysis and spectroelectrochemistry and a mechanism for the reaction involving the reduced porphyrins and DDT is proposed. Comparisons are also made between the catalytic properties of metalloporphyrins containing iron, cobalt and manganese central metal ions under the same solution conditions.     

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 .     

Adsorption of Nonionic Surfactant from Its Aqueous Solution onto Commercial Rubber

Adsorption of Ethoxylated Nonyl Phenol (ENP) surfactant from its aqueous solution onto a commercial tire cutting from different sites. Outer Peristalitic (O.P.), Outer Smouth (O.S.), and Internal Tire (I.T.) is studied after different immersion times, 24, 48, 72, and 144 hrs at 30° C. The adsorption isotherms are determined by a surface tension method. A two stepped L-type isotherm is characteristic below the CMC of ENP; above this concentration the isotherm deviates from the L-type and the slope of the isotherm increases sharply. A Langmuir fit has been found below the CMC of ENP. From the maximum amounts adsorbed at pseudo-plateau (T_max of the tested samples it was found that the efficiency of adsorption onto the rubber surface decreases in the order, O.P. > O.S. > I.T.     

FUNCTIONS OF LIPIDS ON HUMAN SKIN

In order to clarify the roles of lipids in the water-holding property of stratum corneum, the forearm skin of healthy male volunteers was treated with acetone/ether (1/1) or sodium dodecyl sulfate (5%) for 1-30 min. A prolonged treatment period of 5-30 min produced a chapped and scaly appearance of the stratum corneum without any inflammatory reactions. Under these conditions, there was a marked decrease in the water-holding capacity of the stratum corneum accompanied by a selective loss of stratum corneum lipids such as cholesterol, cholesterol esters, and sphingolipids. Two daily applications of the isolated stratum corneum lipids to experimentally induced dry skins caused a significant increase of conductance, accompanied by a marked improvement in the level of scaling. Meanwhile, the isolated sebaceous lipids exhibited no significant recovery in both the conductance value and the scaling. Out of chroma-tographically separated fractions of the stratum corneum lipids, topical applications of ceramide fraction induced the highest increase in the conductance value. Topical applications of synthesized pseudo-ceramides also showed a significant recovery of the water-retaining properties accompanied by an improvement in the scaling only when the polar group has an amide bond in the major linkage. Analysis of the alkyl chain structures has revealed that a structural requirement for the recovery of the water retaining capacity is the presence of saturated-straight alkyl chains, not unsaturated or branched alkyl chains. These structural characteristics required for water-retaining function also paralleled their capacity to form multiconcentric lamellae vesicles in vitro which is also capable of acquiring bound water as shown by DSC thermograms. The present study suggests that ceramides with relatively shorter alkyl chain length serve as a water modulator in the multi-lipid bilayers through the stratum corneum.     

THE INTERACTION OF WATER SOLUBLE MEAT PROTEINS WITH MONO-GLYCERIDE AND DIGLYCERIDE AT THE CORN OIL-WATER INTERFACE ANDITS EFFECTONTIME-DEPENDENT INTERFACIALTENSION REDUCTION.

The influence of water soluble meat protein (WSMP) /glyceryl monostearate/glyceryl distearate ratio on the time-dependent reduction of interfacial tension at the corn oil-water Interface has been investigated at pH's 2.5, 3.5 and 9.5.The total WSMP-glycerides content was kept constant at 1.0% wt/wt. Both variables had an effect, with maximum reduction in the steady state interfacial tension occurring when using 0.5% WSMP in conjunction with 0.5% glycerides (monoglyceride/diglyceride ratio 3/1) at pH 3.5.Under these conditions the WSMP and glycerides associate to form a complex at the interface. At other WSMP/glycerides ratios the interfacial film has a more heterogeneous composition,.     

A STUDY OF THE PRIMARY ELECTROVISCOUS EFFECT IN PYREX GLASS SUSPENSIONS.

An experimental investigation on the electrokinetic phenomenon known as primary electroviscous effect is described for suspensions of Pyrex glass, a highly charged and well known material. By means of an automatic method, the viscosity of the suspensions is measured for different volume fractions of solids, at various electrolyte concentrations and pH values. These measurements allow the estimation of the electroviscous coefficient, p. The electrophoretic mobility was determined for the same systems and zeta potential calculated from these experimental data in order to carry out the comparison between the measured values of p and different theoretical predictions. A qualitative agreement between theory and experiment was found in many cases, but the rigorous theories seem to systemmatically underestimate the experimental p values. The reasons for this disagreement are discussed in addition to the general trends of the electrokinetic behaviour of Pyrex glass.     

CATIONIC POLYMERIC SURFACTANTS

An influence of polyvinyl alcohol molecular weight and acetate groups, present in the macromolecule, on adsorption and electrochemical properties of the TiO₂–polymer solution interface was studied. Calculated thickness of adsorption layers of PVA, on the surface of the oxide, allowed assume that acetate groups may have meaningful influence on the polymer chain conformation at the interface. Structure of macromolecules at titania–polymer solution interface was compared with that of bulk of solution. Obtained data allow determine the changes of the size and shape of polymer coils in the system. The results of experiments let us conclude main factors, responsible for observed zeta potential and surface charge changes of TiO₂. It was proved that change of the ion structure of Stern layer, depends on molecular weight and number of acetate groups (degree of hydrolysis) of PVA macromolecule. Possible mechanism of zeta potential changes was proposed as a function of pH of the solution and molecular weight of the polymer.     

Supramolecular main-chain liquid crystalline polymers and networks with competitive hydrogen bonding

A series of supramolecular polymers and networks with variable liquid crystalline characteristics have been created. These species are formed though the benzoic acid/pyridine associations of a flexible bisacid and a mixture of a rigid bispyridyl and a non-mesogenic tetrapyridyl. The networked systems displayed liquid crystalline characteristics up to and including 22.5% netpoint inclusion. Above this concentration, only crystalline and melting behaviours were observed. This observed phenomenon would seem to be linked to the statistical correlation of hydrogen bond acceptors and donors. There was also no observed phase segregation of the species after multiple heat/cool cycles and extended periods of time in the isotropic state. This would indicate that the thermodynamically more stable mesogenic phase cannot out-compete the non-liquid crystalline network. Computational analysis indicates no significant difference in hydrogen bond strength between the two different hydrogen bond acceptors.