Adiabatic gas absorption in packed columns with large thermal effects

The performance of packed bed adiabatic gas absorbers has been analyzed using the enthalpy and material balance equations incorporating a new parameter, f_r, defined as the fraction of the heat of absorption that is accounted for in the gas stream. An experimental programme to evaluate f_r was carried out and the data correlated. It was found that f_r was dependent on the thermo-physical properties and the hydrodynamic conditions. It is postulated that the mechanism by which this heat transfer occurs is by turbulence at the interface and by entrainment.     

Identification of a novel antigenic structure of the human receptor for interleukin-6 involved in the interaction with the glycoprotein 130 chain

PURPOSE: To evaluate the diagnostic accuracy of positron emission tomography (PET) with administration of 2-deoxy-2-[fluorine-18]fluoro-D-glucose (FDG) relative to that of magnetic resonance (MR) imaging and/or computed tomography (CT) in recurrent head and neck cancers. MATERIALS AND METHODS: Twelve adult patients (mean age, 63 years) with previously treated head and neck cancers and clinical suspicion of recurrence underwent FDG PET and MR imaging and/or CT. All images were blindly and independently interpreted without histopathologic findings (obtained within 1 week of imaging). The level of confidence in image interpretation was graded by using a five-point rating system (0 = definitely no recurrence to 4 = definite recurrence). RESULTS: Recurrence was confirmed in eight patients. With a rating of 4 as a positive finding, FDG PET yielded a sensitivity and specificity of 88% (seven of eight) and 100% (four of four), respectively; MR imaging and/or CT, 25% (two of eight) and 75% (three of four), respectively. Receiver-operating characteristic analysis showed significantly better diagnostic accuracy with FDG PET than with MR imaging and/or CT (area under curve = 0.96 vs 0.55, P < .03). CONCLUSION: These data indicate that PET metabolic imaging, as compared with anatomic methods, has improved diagnostic accuracy for recurrent head and neck cancer.     

N2- and C8-substituted oligodeoxynucleotides with enhanced thrombin inhibitory activity in vitro and in vivo

2'-Deoxyguanosine (G) analogues carrying various hydrophobic substituents in the N2 and C8 positions were synthesized and introduced through solid-phase synthesis into 15-mer oligodeoxynucleotide, GGTTGGTGTGGTTGG, which forms a chairlike structure consisting of two G-tetrads and is a potent thrombin inhibitor. The effects of the substitutions at N2 and C8 of the G-tetrad-forming G residues on the thrombin inhibitory activity are relatively small, suggesting that these substitutions cause relatively small perturbations on the chairlike structure formed by the oligodeoxynucleotide. Introduction of a benzyl group into N2 of G6 and G11 and naphthylmethyl groups into N2 of G6 increased the thrombin inhibitory activity, whereas other substituents in these positions had almost no effect or decreased the activity. Particularly, the oligodeoxynucleotide carrying a 1-naphthylmethyl group in the N2 position of G6 showed an increase in activity by about 60% both in vitro and in vivo. Substitutions on the N2 position of other G residues had little effect or decreased the activity. Introduction of a relatively small group, such as methyl and propynyl, into the C8 positions of G1, G5, G10, and G14 increased the activity, presumably due to the stabilization of a chairlike structure, whereas introduction of a large substituent group, phenylethynyl, decreased the activity, probably due to the steric hindrance.     

Effect of silane coupling agents on mechanical and thermal properties of polyester resin concrete

Polyester resin-quartzite aggregate composites have been investigated for the effect of two silane coupling agents (γ-aminopropyl triethoxy silane andγ-methacryloxy propyl trimethoxy silane) on the mechanical and thermal properties. The integral blend additive method of application of the coupling agent was used in the preparation of the samples. Variation of the thermal stability and the compressive strength with the nature and the content of the silane coupling agent were quite consistent. The properties showed maxima around a certain value of the coupling agent content, which is suggested as the optimum value. Results are also presented on the samples containing an additional filler, namely, the CaCO₃.     

Development of a microassay for estradiol receptors

The calculation of equilibrium binding constants for a specific receptor-hormone interaction requires the exact determination of the unbound ligand concentration and the specifically bound concentration at equilibrium. These determinations usually require corrections for the contribution of non-specific binding. We introduce several parameters allowing equilibrium concentrations to be calculated from experimental concentration values; these parameters can be measured for the particular receptor assay procedure used. These parameters are used in a microassay of estradiol-receptor complex by selective retention on DE-81 cellulose paper.     

Vorstellungen über Entstehung,Wachstum und Abscheidung von Desoxidationsprodukten in Stahlschmelzen

Erörterungen zur homogenen Keimbildung und zur Berechnung der kritischen Übersättigung bei der Desoxidation von Eisenschmelzen mit Mangan. Behandlung des Wachstums der Desoxidationsprodukte durch Diffusion und Kollision. Aussagen über die zeitliche Verteilung der Desoxidationsprodukte unter Berücksichtigung von Stokes- und Gradient-Kollision. Angaben über die Bedeutung der Grenzflächenspannung zwischen Schmelze und Einschluß für die Abscheidung der Desoxidationsprodukte.     

Spray Drying of Metal Alkoxide Sol for Strontium Titanate Ceramics

Conditions for obtaining a stable sol in an isopropyl alcohol–water medium containing titanium isopropoxide and strontium nitrate, and acetic acid as a modifier, have been described. Spray drying of the sol results in submicrometer spherical agglomerates which on further thermal decomposition yield submicrometer particles of strontium titanate at temperatures as low as 500°C. The thermal decomposition characteristics of the spray-dried precursor and the development of strontium titanate phase have been discussed. Calcined precursor powder possesses a specific surface area of 12m²/g, a comp action density of 57%, and a sintered density of > 98%. The optimum sintering temperature of such a powder was 1450°C, which resulted in a sintered grain size around 1.5 μm. Further, such a sintered sample had a dielectric constant of 260 and a loss factor of 0.008 at 1 kHz. This method appears to be very convenient with respect to handling of stable sols and thus avoids the usual difficulties regarding extended gelation as well as inhomogeneous precipitation.     

Estimation of viscosity and thermal conductivity of R142b and R152a

In this paper the viscosity and thermal conductivity of both the liquid and vapour for the refrigerants R152a and R142b have been estimated and presented. Available properties of liquid thermal conductivity of R142b and R152a and the liquid viscosity of R152a are compared with the estimated values. It is found that the agreement is good. Transport properties of R142b, which is a potential replacement for R114 in medium temperature heat pump applications, is compared with that of R114. Also, the properties of R152a, which is considered as a possible replacement of R12 in refrigeration and low-temperature heat pump applications, is compared with the properties of the other possible replacement of R134a.