Heat and mass transfer in abnormal metal plasticity

The authors show the decisive role and special features of heat and mass transfer in the mechanism of abnormal plasticity and in formation of thermomechanical dissipative structures under large plastic strains by the examples of computer modeling of stretching of a specimen, high-pressure torsional shear in a Bridgeman chamber, and shearing strain of a material in the form of flow of a quasiviscous liquid in a channel with local heat removal via a stationary wall.Izhevsk Mechanical Institute. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 1–2, pp. 127–131, July–August, 1994.     

An automated film reader for DNA sequencing based on homomorphicdeconvolution

An automated reader for electrophoresis based DNA sequencing methods is described that provides fast and accurate sequence determination. Digitized sequencing lanes are processed with homomorphic blind deconvolution in preparation for peak detection, interlane alignment, peak refinement and base calling. Initial reads from direct blot sequencing films have error rates of about 1% at the rate of 5 nucleotides/s. Typical read lengths are 500-600 nucleotides. The described reader is a significant improvement over existing readers and could be an essential component in the sequencing efforts of the Human Genome Project     

Pressure ulcer development

VDD pacing follow-up is similar in pediatric and adult patients. Atrial and ventricular pacing parameters are stable during 2-year follow-up in children, and single-pass lead VDD pacing is recommended when the sinus node function is normal.     

Evaluation of hot hardness and creep of a 350 grade commercial maraging steel

The hardening response and the indentation creep of a 350 grade commercial maraging steel were evaluated using a hot hardness tester. The hardness versus temperature plot exhibited three distinct regions. Hardness response was noted between 500–800 K. The unusually high values of activation energy and stress exponent obtained during the creep experiment could be rationalized by a novel concept of introducing a back stress term in the indentation creep relation. The corrected value of the activation energy was found to be reasonably in agreement with the activation energy for diffusion of Ni in iron. Results are supplemented with microstructural observation.     

Construction and characterization of a set of E. coli strains deficient in all known loci affecting the proteolytic stability of secreted recombinant proteins

Even though secretion offers numerous advantages for the production of proteins in Escherichia coli, the expression of many heterologous proteins is severely limited by degradation in the periplasmic space. We found that mutations in rpoH, the RNA polymerase sigma factor responsible for heat shock protein synthesis, affect the stability of heterologous secreted proteins. A particularly dramatic increase in expression was further observed in rpoH degP double mutants. To minimize proteolytic degradation, we constructed a family of 25 isogenic strains deficient in all known cell envelope proteases (DegP, Protease III, Tsp(Prc), and OmpT), as well as the rpoH15 mutant allele, and characterized their growth in both shake flasks and fermentors. The availability of this set of strains permits the selection of a suitable host based on the optimal combination between the optimum reduction in protease activity and acceptable growth properties.