Inactivation of Semliki Forest Virus in aerosols

Purified Semliki forest virus in aerosols is inactivated rapidly at 40% and above 70% relative humidity. At all humidities tested the decay of virus infectivity runs parallel with the decrease in hemagglutination activity, whereas the biological integrity of the virus ribonucleic acid is preserved. Also, free infectious ribonucleic acid is stable after spraying at all relative humidities. Evidence is presented for the hypothesis that above 20% relative humidity, virus inactivation in aersols is mainly due to surface-dependent factors, damaging the virus coat.     

Expression of a rat glutathione-S-transferase complementary DNA in rat mammary carcinoma cells: impact upon alkylator-induced toxicity

The role of glutathione-S-transferase (GST) in alkylator drug resistance has been studied in MatB rat mammary carcinoma cells. A series of GST transfectant cell lines was established by using an expression vector containing the complementary DNA for the rat GST Yc gene under regulation of the SV40 early region promoter and the antibiotic resistance plasmid pSV2neo. Transfectant cell lines expressing up to 4-fold higher total GST activity than in the parental wild type cell line were identified. Southern blot analysis confirmed a DNA fragment corresponding in size to the transfected GST Yc complementary DNA. Wild type MatB cells contain very low levels of Yc protein, whereas the Yc+ clones showed greatly increased amounts of the Yc subunit. The effect of increased GST Yc activity on the sensitivity of the transfected clones to various cytotoxic agents was assessed by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell survival assay. The clones expressing recombinant GST Yc were more resistant to melphalan (6- to 12-fold), mechlorethamine (10- to 16-fold), and chlorambucil (7- to 30-fold). In late passage populations of the GST Yc+ clones that had been grown over a period of 14 months under continuous selection in G418, GST activity was decreased and it was paralleled by a decrease in Yc protein. These late passage clones with diminished GST Yc content also demonstrate a partial reversion toward the wild type phenotype as determined by cytotoxicity assays using melphalan, mustargen, and chlorambucil. Interstrand DNA cross-links induced by mechlorethamine were significantly lower at 0, 2, and 20 h posttreatment in one of the GST Yc+ clones when compared to wild type MatB cells. These studies indicate that GST Yc overexpression can confer resistance to alkylating agents and that this correlates with inhibition of DNA cross-link formation.     

An algorithm for generating solid elements in objects with holes

An algorithm for dividing an object with holes into solid elements for finite element preprocessing is presented. Since a tetrahedron can always be subdivided into prisms and cuboids, the approach of first dividing the given object into disjoint tetrahedra is taken.Objects without holes are dealt with first. Two mesh operators, each generating a single tetrahedron, are presented. In addition to the construction procedure, it is shown that they handle all objects without holes. The algorithm for objects with holes requires a third operator. In addition to showing the necessary and sufficient condition for applying such an operator, it is shown that it effectively reduces the number of holes in an object by one while yielding three tetrahedra. The algorithm which sequences the three operators thus reduces a given polyhedron to a single tetrahedron iteratively. Data structure requirements and update procedures are also given in this paper.     

Strain-rate effect on high temperature low-cycle fatigue deformation of AISI 304L stainless steel

The effect of strain rate on the behaviour of high temperature low-cycle fatigue is investigated for AISI 304L stainless steel. Regardless of the test temperature of 873 or 973 K, the fatigue life is saturated in the strain-rate range of slower than 4 × 10^–3 sec^–1. Also it is interesting to note that serrated flow, which is evidence of the occurrence of dynamic strain ageing, is clearly observed in the load-elongation hysteresis loops for strain rates that are slower (at 873 K) and faster (at 973 K) than 4 × 10^–3 sec^–1. Since the combination of temperature and strain rate is concerned with the phenomenon of dynamic strain ageing, it is considered that the above-mentioned saturated fatigue life at 873 K is caused by dynamic strain ageing and that the hardening effect due to dynamic strain ageing abnormally increases the fatigue life. However, even though the behaviour of fatigue life under strain rates slower than 4 × 10^–3 sec^–1 at 973 K has nothing to do with the dynamic strain ageing, it has been found that the failure life is also saturated in this slower strain-rate range. This behaviour is considered to be caused by the effect of creep, because the deformation under the low strain-rate activates the recovery process and as a result it causes saturation of the inelastic strain range.     

Cerebrospinal fluid methylmalonic acid concentrations in neurological patients with low and normal serum cobalamin concentrations

OBJECTIVE: To determine whether cerebrospinal fluid (CSF) methylmalonic acid (MMA) is increased in neurological patients with low serum cobalamin (Cbl, vitamin B12) concentrations as opposed to neurological patients with normal serum Cbl concentrations. MATERIAL AND METHODS: We measured MMA concentrations in serum and CSF of neurological patients with low serum cobalamin concentrations, but without overt cobalamin related manifestations such as anemia or combined disease of the cord, and neurological patients with normal serum cobalamin concentrations (controls). RESULTS: Serum and CSF MMA concentrations were significantly higher in patients than in controls. Serum MMA was elevated in 4 patients of whom 3 had clearly elevated CSF MMA concentrations. CONCLUSION: Strong indications for cobalamin deficiency can be found not only in serum but also in CSF of patients with seemingly asymptomatic low serum cobalamin concentrations.     

Miscible blends of a vinylidene chloride/vinyl chloride copolymer with aliphatic polyesters

A copolymer of vinylidene chloride and vinyl chloride containing 13.5% by weight of the latter has been solution blended with four aliphatic polyesters: poly(?-caprolactone), poly(2,2-dimethyl-1,3-propylene adipate), poly(1,4-cyclohexanedimethylene succinate), and poly(2,2-dimethyl-1,3-propylene succinate). Each blend was examined visually and by differential scanning calorimetry. All blends with the copolymer form a single miscible amorphous phase at all compositions and all temperatures except for the latter mentioned polyester, which exhibits liquid–liquid phase separation at temperatures above a measured cloud point curve. Information about interactions between the components in each blend is estimated from melting point data and discussed.     

Realizable feed-element patterns for multibeam reflector antenna analysis

The radiation pattern of a feed element is approximately described by a simple function(cos theta)^{q}. For a given element spacing of the feed array, we give simple formulas for estimating the practical value ofqwhen the element is an open-ended rectangular waveguide, an open-ended circular waveguide, a pyramidal horn, or a cigar antenna.