Bulky Water Research Articles

Cobaloximes as Environmentally Advantageous Alternatives to Organotin Hydrides in Iodine Atom Abstraction Routes to Benzyl Radicals

High yields of alkyl radicals derived from alkylcobaloximes have been achieved using tungsten light (or in some cases ultrasound) radiation in both organic and aqueous media. These improved yields are obtained when pyridine (the usual base ligand) is replaced by suitably bulky lone-pair donors or water. The alkyl radicals so generated take part in iodine abstraction reactions with benzyl iodides giving benzyl radicals which may be trapped in near-quantitative yield with 2,2,6,6-tetramethyl-piperidinyloxy (TEMPO) or in good yield with lepidinium (4-methylquinolinium) triefluoroethanoate or lepidinium camphor-10-sulphonate. The usual drawbacks of cost and tedious work-up procedures associated with the more commonly used organotin hydride reagents are avoided

Modulation of interaction forces between bilayers exposing short-chained ethylene oxide headgroups

The use of liposomes as drug delivery systems has been limited by their rapid clearance from circulation by the mononuclear phagocyte system. Recent studies have found that circulation times can be greatly enhanced by incorporating a small amount of modified lipids whose headgroups are derivatized with a bulky water soluble polymeric chain of poly ethylene oxide. We report here a systematic study using the Surface Forces Apparatus to measure directly the interactions between two phosphatidyl ethanolamine lipid bilayers, exposing this polymeric headgroup at different concentrations in the bilayer. We found that the force becomes repulsive at all separations and that the thickness of the steric barrier could be controlled easily by adjusting the concentration of the modified lipids. Equilibrium force profiles were measured that were reversible and largely insensitive to changes in electrolyte concentration and temperature. The results have enabled the Dolan and Edwards theory for the steric forces of low coverage polymer surfaces and the Alexander de Gennes theory for high coverage surfaces to be tested, and both were found to apply. We conclude that these simple theories can be used to model the interactions of surprisingly short segments and, hence, apply to such systems as lipids with bulky headgroups and liposomes containing a sterically stabilizing polymer.

ChemInform Abstract: IR and Gravimetric Studies of the Adsorption of Water on Barium Sulfate.

AbstractA self‐supporting disc of BaSO4 is freed from adsorbed and bulky water by heat treatment at 773 K. Subsequent adsorption of water vapor gives spectra containing IR bands due to isolated hydroxyl groups and to vibrations of water molecules.

Structure and stability of tetrapropyl-ammonium (TPA) ions in various alkali—aluminosilicate hydrogel precursors to crystalline (M)ZSM—5 zeolites

The stability of TPA species interacting with various (Al,Si) hydrogel environments in the presence of alkali cations has been evaluated by thermal analysis (combined t.g.-d.t.a.-d.t.g.). Three different TPA—gel associations have been characterized by d.t.a. endotherms : crystalline (TPAX) n clusters (X = OH −,Br −) which are also detected by XRD, monomeric (TPAX) species in direct association with the (Al,Si) gel, and labile entities, [TPA +…(H 2O) x] bulky water clathrates, that interact very weakly with the remaining negative charges available after neutralization of the gel by small (Li,Na,K) alkali cations. The formation, relative concentration and stability of these species essentially depend on the relative amounts of Al 2O 3 and M 2O present in the gel, as well as on the nature (structure forming/breaking) of the alkali cations. Monomeric as well as water clathrated species lead to crystalline (M)ZSM—5 upon heating.

Composite ionberg–iceberg model of aqueous nonpolar solvation and water exchange reactions

A new model for aqueous solvation and water exchange reactions of large apolar solutes is proposed which radically extends the iceberg model of Frank and Evans. In the iceberg model each apolar molecular is encased in a cage of bulky water (a microscopic iceberg) whose extent increases with the size of the solute molecule. For small solute molecules the iceberg may have an incipient clathrate cage structure. In the composite ionberg–iceberg model when the solvent molecule is too large to occupy a clathrate interstice, a cloud of dissociated water ions nd(H++OH−) forms a core shell or sheath between the iceberg casing and the solute molecule, with nd increasing as the misfit between the solute and the cage increases. The ionberg model explains the slope and range of the linear phase space compensated activation volume-activation entropy correlations in associative and dissociative chemical reactions with apolar intermediates which are observed for solutes ranging from transition metal complexes to enzymes.

PMBP-loaded polyurethane foam as an extractant for thorium nitrate from aqueous solution

A study on extraction of thorium with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (PMBP)-loaded polyurethane foam is described. Open-cell polyurethane foam has proved to be effective as supporting material for PMBP. Thorium nitrate can be quantitatively extracted by PMBP-loaded polyurethane foam over a wide pH range. The effect of equilibrium time, pH, thorium concentration, various anions and flow-rate on the extraction efficiency of thorium is examined. A technique of extraction chromatography column with PMBP foam cylinder has been developed for trace thorium analysis of bulky water samples.

The problem of water hyacinths in rivers and canals

Abstract The cation exchange capacity (CEC) and content of COOH groups in bulky water hyacinth compost were estimated over the rotting period. The progressive increase observed in the estimates was ascribed to continuing oxidation processes in the composted materials. Fractionation of organic carbon extracted with Na4P2O7-NaOH from the composted materials over the rotting period on the basis of acid-soluble and -insoluble fractions, was carried out. The carbon of humic-like substances (precipitated at pH 2) in the dry matter was almost stable from 0- to 124-day composted materials. There were successive increases in total acidity, and content of carboxyl and phenolic hydroxyl groups in the humic substance extracts indicating progressive oxidation processes in these substances over the rotting period. Elementary analysis and IR spectra provided further support for the above inference and led us to conclude that humification of the water hyacinth consists mainly of structural modification of humic-like subs...

Funnel for Extraction of Leaf Litter Organisms1

At the turn of the century Antonio Berlese developed a method of extracting arthropods from forest litter by enclosing the material in metal funnels and “driving” the organisms through it, by the use of heat and dehydration, into a collecting bottle (Macfadyen 1953; Peterson 1964; Southwood 1966). His method is still employed with little change by many entomological laboratories. Although utilized extensively, the method possesses certain disadvantages. The funnels are not readily adaptable to field use because of the need for bulky equipment and hot water or electric light bulbs as a source of heat. Often, certain forms perish because they are unable to migrate rapidly from the heat source. Volatile preservatives in the collecting bottle often deter organisms from moving into the container.