The synthesis and evaluation of cyclic olefin sulfone copolymers and terpolymers as electron beam resists

Poly(cyclopentene sulfone) (PCPS) and poly(bicycloheptene sulfone) (PBCHS) copolymers have been evaluated as potential positive electron beam resists which have good thermal properties and which show high sensitivity to ionizing radiation. It was found that thin copolymer films could be processed as resists but that films greater than 3000 Å thick cracked in the solvents used to dissolve the radiation-exposed regions. Incorporation of plasticizing additives did not improve the film properties. Films from low molecular weight polymer fractions cracked less in solvents, but higher radiation doses were required to offset the reduced sensitivity. This resulted in the formation of intractable residues in the exposed regions which appear to be crosslinked polymer. Bicycloheptene monomers with specific functional groups did not improve the properties of the copolymer films. Terpolymerization with α-olefins such as butene-1 and cis-2-butene plasticized these films and reduced their tendency to crack in solvents. Poly(cyclopentene sulfone–co–butene-1 sulfone) films were found to have the best properties, and 1.25-μ resist images could be etched in SiO₂ layers at an exposure dose of 4 × 10^?6 C/cm² at 25KV. However, one important limitation of this terpolymer was the low dissolution rate ratio between the exposed and unexposed regions. Since straight-walled relief images are essential to the formation of high-resolution patterns, the usefulness of this terpolymer as an electron beam resist appears to be hindered by the limited choice of good solvents to maximize the dissolution rate ratio. PBCHS block terpolymers containing methyl methacrylate (MMA) or methacrylic acid (MAA) were synthesized to improve the solubility in solvents and to incorporate the properties of methacrylates. PBCHS–MMA films cracked in solvents after irradiation; PBCHS–MAA polymers were too insoluble to form resist films.     

Inert-marker studies during high-temperature formation of FeS2 from FeS1 + x

Marker experiments were made during the growth of FeS₂ upon FeS_1.128 at 650 °C. From the position of the markers in the scale, it was determined that the sulphur motion in FeS₂ was similar to that of the iron motion. Such motion may have occurred from solid-state diffusion in the FeS₂ or from gaseous transport in the micropores present in the FeS₂.     

Studies of silver iodide ice-forming activity. i. influence of the aerosol particle size on the ice-forming activity at —20°C

Silver iodide ice-forming activity has been studied at the supercooled fog temperature —20°C. The number of ice crystals calculated per gram reagent depends greatly on the aerosol particle mean cubed radius. The analysis of published data shows that this is the principal cause of a considerable divergence in the data on silver iodide ice-forming activity obtained by various authors.     

MICROWAVE VACUUM DRYING KINETICS OF SOME FRUITS

Microwave vacuum drying kinetics of three fruits (namely, apple, kiwi and pear) were studied by introducing an one-parameter empirical mass transfer model, involving a characteristic parameter (drying constant), as a function of process variables. The model was tested with data produced in a microwave oven equipped with vacuum apparatus, using non-linear regression analysis. The investigation involved a wide range of microwave power and vacuum pressure levels. The parameters of the model considered were found to be greatly affected by the microwave power level while vacuum pressure affected slightly the process.     

Alcoholysis of palm oil mid-fraction by lipase from Rhizopus rhizopodiformis

A mycelial lipase from Rhizopus rhizopodiformis was prepared in fragment form. The lipase was examined to catalyze the alcoholysis of palm oil mid-fraction (PMF) in organic solvents. High percentage conversions of PMF to alkyl esters were achieved when methanol or propanol was used as acyl acceptor. Of the two most prevalent fatty acids in PMF, palmitic acid seemed to be preferred over oleic acid in the formation of methyl and propyl esters. The optimal ratio of oil to methanol in the alcoholysis reaction is 1 to 2 moles. The lipase exhibited high alcoholysis activities in nonpolar solvents (log P>2), such as hexane, benzene, toluene, and heptane. The enzyme showed exceptionally high thermostability.     

Synthesis of alkyloxy (di)alkylamino propanols, hydroxy alkyloxy (di)alkylamino propanols, and the dimer compounds for use as fuel additives

Alkyl glycidyl ethers and bis glycidyl ethers, synthesized in a heterogeneous weakly hydrous medium, were condensed with primary or secondary amines to obtain 3-alkyloxy propanolamines or bis alkyloxy propanolamines in a regioselective manner. The compounds were characterized by conventional spectroscopic methods, and complete nuclear magnetic resonance data are given. Their high-temperature stability, their good emulsifying power, their oxidation, and corrosion inhibition make these compounds suitable for solubilizing ethanol-diesel fuel blends.     

Soil Material Porosity Characterization by Thermal Desorption of Liquids

Thermal desorption of acetone and benzene from soil materials was investigated by using quasi-isothermal thermogravimetric technique.Experimentally obtained curves representing mass loss of adsorbate against temperature were converted into plots of adsorbent pore volume versus plate separation. The transformation was performed by applying the Kelvin equation. Calculated distributions and total pore volumes were consistent with the results obtained from nitrogen sorption and mercury intrusion measurements.     

Alkylation of pyrazoles with alcohols over zeolites

HY zeolite is a highly active catalyst for the vapor-phase N-alkylation of pyrazoles with alcohols. For example, the reactions of pyrazole and 4-methylpyrazole with methanol over HY afford N-methylpyrazole and 1,4-dimethylpyrazole, respectively, in a 100% yield at 573 K. This revised version was published online in July 2006 with corrections to the Cover Date.     

Behaviour of the Antitumor Agent Vanadocene Dichloride in Physiological and Therapeutic Media, Blood Plasma and Human Blood - An EPR Study

By means of EPR spectroscopy the behaviour of the vanadocene dichloride (I), Cp(2)VCl(2) (Cp=eta(5)-C(5)H(5)), in various deoxygenated and non-deoxygenated physiological media and therapeutic solution as well as in blood plasma and stabilized human blood was studied. On the basis of measured values of isotropic spectroscopic splitting factor g(iso) and isotropic hyperfine coupling constant A(iso), the vanadocene species, [Cp(2)V(H(2)O)Cl](+) (II; g(iso)= 1.985, |A(iso)| = 7.68 mT), [Cp(2)V(H(2)O)(2)](2+) (III; g(iso)= 1.983, |A(iso)| = 7.92 mT), [Cp(2)V(OH(2) (IV; g(iso)= 1.991, |A(iso)| = 6.285 mT), [Cp(2)VCl(DMSO)](+) (V; g(iso)= 1.985, |A(iso)| = 7.69 mT), the vanadyl species [VO(DMSO)(5)](2+) (VI; g(iso)= 1.964, |A(iso)| = 10.78mT) and [VO(H(2)O)(5)](2+) (VII; g(iso)= 1.955, |A(iso)| = 11.56 mT) have been identified. From the measurements it follows that I does not react in its first coordination sphere with any component of a system used other than water and DMSO, resp. As to water-containing media, its behaviour is fully consistent with that of I in pure aqueous media. It was found the only vanadocene species present after application of the therapeutic solution of I into human blood to be IV not interacting in its first coordination sphere with any blood component.     

Constrained Densification of Alumina/Zirconia Hybrid Laminates, II: Viscoelastic Stress Computation

To analyze the inhibited densification during sintering and differential shrinkage during cooling of Al₂O₃/ZrO₂symmetric and asymmetric laminates, viscoelastic formulations, in which the viscosity and elastic modulus vary with time, have been developed. The viscoelastic mismatch stresses have been numerically computed over the entire processing cycle, including the heating period, the isothermal period, and the cooling period. The viscosity and free sintering rates that are needed for stress computation have been obtained by modifying the parameters that are measured for a normal isotropic densifying compact using cyclic loading dilatometry. The modification is based on the available sintering models to account for the effect of strain history on compact viscosity and sintering rates. The stress calculation shows that, with the exception of the initial heating period, the viscoelastic stress is identical to the viscous stress that is calculated solely from the strain rate mismatch. Sintering damage in the laminates is shown to occur during densification under conditions where the differential sintering stress is smaller than the intrinsic sintering pressure. The magnitude of residual stress in hybrid laminates on cooling is dependent on the cooling rate, and slower cooling rates are capable of almost completely relaxing the expansion mismatch stress at temperatures of >1200°C.