Two neighbouring quasi-trapezoidal holes in discs with minimum s.c.f.

Using a two dimensional photoelastic technique, hole shapes have been optimised in diametrically loaded circular discs with two neighbouring holes leading to minimum stress concentration factor (s.c.f.). Two neighbouring holes symmetrically located side by side with the load axis perpendicular to the line joining the centres of the holes are considered. Results are given for a range of disc diameter/hole diameter ratios (11.44≥D/d≥4.16). Optimised quasi-trapezoidal hole geometries, stress distributions around these holes and the effect of tilting the load direction are presented. In comparison with circular holes, the s.c.fs. have been reduced up to about 14% with quasi-trapezoidal holes at regions of peak stresses and up to 23% at peak tensile stress regions.     

Purification, cDNA cloning and heterologous expression of human phosphomannose isomerase

Phosphomannose isomerase catalyses the interconversion of fructose-6-P and mannose-6-P and has a critical role in the supply of D-mannose derivatives required for many eukaryotic glycosylation reactions. Three classes of enzymes possessing phosphomannose-isomerase activity have been identified in bacteria and lower eukaryotes. We have purified human phosphomannose isomerase to homogeneity from placental tissue. Protein sequence information obtained from internal fragments of the protein was used to design degenerate oligonucleotides which were used to amplify a fragment of a human phosphomannose-isomerase cDNA. A full-length cDNA was isolated from a human testes lambda gt11 library using this fragment as a probe. The cDNA encoded a protein with significant sequence identity to fungal and some bacterial phosphomannose isomerases but was unrelated to those from other bacteria. Based on amino acid sequence identity we propose a classification system for enzymes with phosphomannose-isomerase activity. The cDNA, under the control of the GAL1 promoter, was expressed in a Saccharomyces cerevisiae strain from which the native gene encoding phosphomannose isomerase had been deleted. The human enzyme was found to be able to functionally substitute for the yeast enzyme. Phosphomannose-isomerase mRNA was found in all human tissues tested but was more highly expressed in heart, brain and skeletal muscle. The cDNA was expressed in Escherichia coli permitting the isolation of pure recombinant protein which will be used for kinetic and structural studies.     

Speaker verification: a tutorial

The task of speaker verification, a subset of the general problem of speaker recognition is defined. The feature selection and pattern matching steps of the recognition procedure are examined. Speaker verification system design and performance are discussed, and databases for evaluating them are briefly considered. An example of a speaker verification system is described. An overview of industry research in this area is given     

The in Vitro and in Vivo Performance of a Novel Slow Release Capsule-Compared with a Conventional Capsule

A comparative in vitro and in vivo performance study of a novel slow release capsule (prepared using the new laser drilled controlled drug delivery system) and a conventional capsule dosage from has been made using tetracycline hydrochloride as a model drug. The influence of variation in drug delivery system design on the in vivo performance was studied by urinary excretion rate studies in human volunteers. Slow release capsules released its contents relatively slowly, over a period of time, both in vitro and in vivo, as compared to conventional capsules, with significantly similar K_e and t_1/2 values. Plasma C_max and t_max and AUC values were predicted based on the reported correlation between serum and urinary excretion data in single dose trials.     

Ceramic nanoparticle assemblies with tailored shapes and tailored chemistries via biosculpting and shape-preserving inorganic conversion

A novel biosynthetic paradigm is introduced for fabricating three-dimensional (3-D) ceramic nanoparticle assemblies with tailored shapes and tailored chemistries: biosculpting and shape-preserving inorganic conversion (BaSIC). Biosculpting refers to the use of biomolecules that direct the precipitation of ceramic nanoparticles to form a continuous 3-D structure with a tailored shape. We used a peptide derived from a diatom (a type of unicellular algae) to biosculpt silica nanoparticle based assemblies that, in turn, were converted into a new (nonsilica) composition via a shape-preserving gas/silica displacement reaction. Interwoven, microfilamentary silica structures were prepared by exposing a peptide, derived from the silaffin-1A protein of the diatom Cylindrotheca fusiformis, to a tetramethylorthosilicate solution under a linear shear flow condition. Subsequent exposure of the silica microfilaments to magnesium gas at 900 degrees C resulted in conversion into nanocrystalline magnesium oxide microfilaments with a retention of fine (submicrometer) features. Fluid(gas or liquid)/silica displacement reactions leading to a variety of other oxides have also been identified. This hybrid (biogenic/synthetic) approach opens the door to biosculpted ceramic microcomponents with multifarious tailored shapes and compositions for a wide range of environmental, aerospace, biomedical, chemical, telecommunications, automotive, manufacturing, and defense applications.