Conductive SnO2/Sb powder: preparation and optical properties

Preparation of an SnO₂ semiconducting powder doped with antimony (x=2.38 mol%) was achieved by co-precipitation. The unit cell parameters of the doped SnO₂ powders were measured and their changes with dopant concentration were determined. Four-point sheet resistance measurements, together with optical and infrared spectra of the powder were taken in order to obtain a highly-conducting, low-emitting powder which could be used for antistatic paint preparation. Evolution of the phonon bands corresponding to Sn-O stretching modes as a function of dopant concentration were followed, and a model calculation based on an extended four-parametric Kurosawa relation was applied to the reflection spectra of differently doped powders. It was found that the frequency of the plasma oscillations shifts with dopant concentration, and the intensity of the reflectivity peaks was correlated with plasmon-phonon interactions. An additional negative reflection peak in the range 1100 to 1200 cm^–1 was found in the reflection spectra of highly doped powders and was attributed to the coupled modes between the plasma oscillations and one of the phonon combinational or overtone modes of SnO₂.     

Glycogen storage disease type II: identification of four novel missense mutations (D645N, G648S, R672W, R672Q) and two insertions/deletions in the acid alpha-glucosidase locus of patients of differing phenotype

Glycogen storage disease type II (GSDII), an autosomal recessive myopathic disorder, results from deficiency of lysosomal acid alpha-glucosidase. We searched for mutations in an evolutionarily conserved region in 54 patients of differing phenotype. Four novel mutations (D645N, G448S, R672W, and R672Q) and a previously described mutation (C647W) were identified in five patients and their deleterious effect on enzyme expression demonstrated in vitro. Two novel frame-shifting insertions/deletions (delta nt766-785/insC and +insG@nt2243) were identified in two patients with exon 14 mutations. The remaining three patients were either homozygous for their mutations (D645N/D645 and C647W/C647W) or carried a previously described leaky splice site mutation (IVS1-13T-->G). For all patients "in vivo" enzyme activity was consistent with clinical phenotype. Agreement of genotype with phenotype and in vitro versus in vivo enzyme was seen in three patients (two infantile patients carrying C647W/C647W and D645N/+insG@nt2243 and an adult patient heteroallelic for G648S/IVS1-13T-->G). Relative discordance was found in a juvenile patient homozygous for the non-expressing R672Q and an adult patient heterozygous for the minimally expressing R672W and delta nt766-785/+insC. Possible explanations include differences in in vitro assays vs in vivo enzyme activity, tissue specific expression with diminished enzyme expression/stability in fibroblasts vs muscle, somatic mosaicism, and modifying genes.     

Gasochromic effect of palladium doped peroxopolytungstic acid films prepared by the sol-gel route

Gasochromic palladium doped peroxopolytungstic acid (Pd:P-PTA) films have been prepared using dip-coating deposition from peroxopolytungstic acid (P-PTA) sols into which PdCl₂ was added in molar ratios Pd:W=1:125, 1:100, 1:53, and 1:40. These films exhibit reversible colouring/bleaching changes when exposed to hydrogen or hydrogen/argon mixture (4%) and air, alternatively. Gasochromically coloured and bleached films were characterised using in-situ Fourier transform infrared (FT-IR) spectroscopy. The vibrational modes of as-deposited, coloured and bleached films were assigned and the polaron absorption, which characterises the IR spectra of coloured films, was detected. Colouring/bleaching kinetics of films exposed to H₂ and H₂/Ar mixture as a function of the concentration of the catalyst and temperature of heat-treatment is reported. Proton (σ_pr) and electronic (σ_el) conductivities determined from impedance spectra revealed an increase in σ_el from 10⁻⁵ S cm⁻¹ in bleached state, to 10⁻³ S cm⁻¹ in coloured state, while σ_pr remained constant (10⁻² S cm⁻¹).     

The influence of paint dispersion parameters on the spectral selectivity of black-pigmented coatings

The optical properties of variously prepared black-pigmented solar absorbing paints were calculated in terms of their effective absorption and scattering abilities. The phenomenological two-parameter Kubelka–Munk effective medium theory was applied. Paints with the same composition were prepared for different degrees of pigment dispersion and characterized by the average size of pigment agglomerates present in the pigment/vehicle system. Prepared paints were applied to aluminum foil in two ways, by coil coating and by spraying. The size of coarse pigment particles and the paint application technique influence the spectral selectivity and thus determine the final performance of spectrally selective surfaces.     

The service of dinas in air-heaters with a remote combustion chamber in a blast furnace of capacity 5000 m<Superscript>3</Superscript>

Expertise in the service of a high-burned compacted dinas in the hot zone of an air heater with an external combustion chamber of a 5000 m3 blast furnace has been considered. The repair-to-repair period for the air heater was 29 years.Translated from Novye Ogneupory, No. 6, June, 2004, pp. 3–6.