Hydrophobic polyelectrolytes and polysoaps. Ionization of weakly basic groups and conformation in aqueous solution of some derivatives of poly(4-vinyl pyridine)

Two different types of cationic polysoaps were prepared in order to study the ionization equilibria of weakly basic groups incorporated in such polymers. A major concern in this work has been an exploration of the effect of temperature on the intrinsic basicity of the ionizable groups, a question of considerable relevance, for example, in the development of thermally regenerable ion exchange resins. The results lead to models that should be helpful in elucidating trends in the basicity of functional groups in polyelectrolytes incorporating hydrophobic residues. A basic resin with greatly enhanced thermal effect has been prepared which provides support for present models of the hydrophobic effect.     

On the effect of pressure on the shear and elongational viscosities of polymer melts

The effect of pressure and temperature on the shear and elongational deformation rate–dependent viscosities has been experimentally investigated for several polymers (HDPE, LDPE, LLDPE, PP, PC, PMMA, and PS) on a capillary rheometer with a back‐pressure device. Pressure, β, and temperature, α, coefficients have been determined through simultaneous fitting of the shear and extensional viscosity data by the modified White‐Metzner model. The dependence of β and α on temperature and pressure, respectively, was investigated and it has been found that simple relationships exist between pressure and temperature sensitivity coefficients for individual polymers. Polym. Eng. Sci. 44:1328–1337, 2004. © 2004 Society of Plastics Engineers.     

Regeneration of a spent photographic fixer solution

An attempt to regenerate an exhausted photographic fixer solution, removing the surplus silver and bromide ions has been made. The ions were removed by electrolysis in a cell containing separate anionic and cationic compartments using ion exchange membranes. Four types of anion exchange membranes in two‐ and three‐compartment cells were used: AMX, ACS (Neosepta, Japan), AMI‐7001 (Ultrex^?, USA), and MA‐40 (PO Stchekino, Russia). Silver deposition occurred at the titanium rotating cylinder cathode and the deposits were compact and bright. The residual silver ion concentration after electrolysis was 0.012–0.014 mol dm^?3. Of the four membranes tested the ACS membrane was the most selective for removal of bromide ions. The current efficiency of bromide ion migration through the ACS membrane was approximately two to five times greater than that achieved with AMX, AMI‐7001 and MA‐40 membranes. After five regeneration cycles the fixer's working quality did not noticeably deteriorate. Copyright © 2004 Society of Chemical Industry     

Role of monoamines in the control of hormones of sexual receptivity in the female rat.

Investigated the involvement of indole- and catecholamines in the hormonal regulation of sexual receptivity in ovariectomized Sprague-Dawley rats. Drugs that reduce 5-hydroxytryptamine, dopamine, and adrenaline or increase noradrenaline neurotransmission tended to facilitate the occurrence of estrous behavior in estrogen-treated Ss, and drugs having opposite effects tended to inhibit receptivity induced by estrogen and progesterone. Estrogen decreased noradrenaline turnover in cortex and brain stem; progesterone enhanced this effect in brain stem but prevented it in cortex. Both hormones tended to block noradrenaline uptake in hypothalamus in vitro. In a schedule used to induce receptivity, estrogen accelerated serotonin turnover, an effect prevented by progesterone. Results suggest that a number of monoamines may be involved in the control by hormones of estrous behavior and that hormones affect both amine turnover and uptake mechanisms. (85 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sizing of hybrid photovoltaic-wind energy systems

A procedure is described which determines the sizes of the PV array and wind turbine in a PV/wind energy hybrid system. Using the measured values of solar and wind energy at a given location, the method employs a simple graphical construction to determine the optimum configuration of the two generators that satisfies the energy demand of the user throughout the year.     

Structures des composes CdTm2S4 et CdYb2S4

The structures of CdTm₂S₄ and CdYb₂S₄ were refined in order to establidh the exact cationic distribution. The R factors are 0.037 for 104 reflections (CdTm₂S₄) and 0.039 for 98 reflections (CdYb₂S₄) Unlike CdHo₂S₄ abd CdY₂S₄, the structures are of normal spinel type and intersticial cation defects are not observed.