Structure and thermomechanical properties of fast-quenched Ti<Subscript>2</Subscript>NiCu alloy ribbons with various crystalline phase fractions obtained by means of annealing by electric current

New promising functional materials—amorphous-crystalline fast-quenched Ti₂NiCu alloys exhibiting the shape memory effect (SME)—are studied. A method for annealing amorphous alloys by electric current pulses is proposed. This method allows one to obtain the needed degree of crystallinity. It is demonstrated that a microcrystalline structure with spherical grains exists in amorphous-crystalline samples. These grains increase in size from 150 nm to 3.2 μm as the degree of annealing increases. The SME is not observed in nontreated samples and is clearly manifested in completely annealed samples. A two-way SME and a trend toward lowering of the martensitic transition temperature are observed in partially annealed samples.     

Dry slaking of coke at OAO Altai Koks

Stable operation of the dry-slaking system at OAO Altai-Koks has been ensured by reconstruction of the waste-heat boilers and discharge system; timely relining of the slaking chambers by up-to-date methods; the introduction of automated control of the slaking system; the introduction of a deaeration and feeder system; and ongoing major repair of the basic equipment.     

Giant reversible deformations in a shape-memory composite material

New scheme of a functional composite material based on a shape memory alloy has been developed and experimentally tested. The proposed scheme ensures a giant reversible bending deformaion using only one-way shape memory. The scheme has been experimentally implemented on models manufactured by galvanic deposition of nickel onto preliminarily pseudoplastically deformed rapidly quenched Ti₅₀Ni₂₅Cu₂₅ alloy ribbons. The proposed scheme is especially promising for applications in micro- and nanomechanics. In particular, prototype nanotweezers have been manufactured on this basis with record small dimensions of 12 × 3 × 1 μm and a 500-nm-thick shape-memory layer, which is capable of manipulating objects with sizes from 10 to 1000 nm. Controlled deformation of nanotweezers was achieved by heating them using semiconductor laser radiation in a vacuum chamber of scanning ion-probe microscope.     

Comprehensive uncertainty and sensitivity analysis for coupled code calculations of VVER plant transients

The development of coupled codes, combining thermal-hydraulic system codes and 3D neutron kinetics codes, is an important step to perform best-estimate calculations for plant transients of nuclear power plants. For applications in safety analysis, these coupled codes should be validated by benchmark calculations and, preferably, by comparison with plant transient data from operating plants. In addition, the results should be supplemented by applying uncertainty and sensitivity analysis methods, which allow to identify relevant parameters of models and solution procedures affecting the results and to quantify their relative importance. Both objectives were part of the VALCO project. The aspect of validation is presented in [S. Mittag, et al., 2004. Neutron-Kinetic Code Validation against Measurements in the Moscow V-1000 Zero-Power Facility, in press; T. Vanttola et al., 2004. Validation of coupled codes using VVER plant measurements, in press], the aspect of a comprehensive uncertainty and sensitivity analysis for coupled code calculations is the topic of this contribution. The results and experiences obtained by the analysis for two plant transients in a VVER-440 and a VVER-1000, respectively, are presented and discussed.     

Production of the STA2-encoded glucoamylase in Saccharomyces cerevisiae is subject to feed-back control

Three modes of production of the extracellular glucoamylase (GA) in Saccharomyces cerevisiae have been identified; repressed, basal and induced. The repressed mode is found with cells grown in rich media containing non-limiting concentrations of monosaccharides or disaccharides, including GA-hydrolysable maltose, as a sole carbon source. Both the basal and the induced modes (spanned by some seven-fold differences in the rate of GA production) can be displayed by either glucose-limited or glycerol-plus ethanol-consuming cultures; the induced mode is switched over to the basal one due to a feed-back inhibition by extracellularly accumulated GA. It is proposed that the feed-back control involved in GA production can be attenuated by starch which can thus 'induce' higher rates of GA production compared to the basal mode.