Laboratory hot-dip aluminizing of sheet steels

It is a matter of common knowledge that in laboratory hot-dip aluminizing, great difficulties are often encountered in preparing specimens that are free of surface oxides and other ubiquitous contaminants such as oils, grease and dust. Inadequate preparation of specimens will inevitably lead to the prevention of alloy layer growth during hot dipping and poor coatings following withdrawal. This paper describes a method for the production on a laboratory scale of hot-dipped type 1 aluminized sheet- steel specimens of commercial quality.     

Edible vaccine protects mice against Escherichia coli heat-labile enterotoxin (LT): potatoes expressing a synthetic LT-B gene

The authors have designed and constructed a plant-optimize synthetic gene encoding the Escherichia coli heat-labile enterotoxin B subunit (LT-B), for use in transgenic plants as an edible vaccine against enterotoxigenic E. coli. Expression of the synthetic LT-B gene in potato plants under the control of a constitutive promoter yielded increased accumulation of LT-B in leaves and tubers, as compared to the bacterial LT-B gene. The plant-derived LT-B assembled into native pentameric structures as evidenced by its ability to bind ganglioside. The authors demonstrated immunogenicity by feeding mice the raw tubers and comparing the anti-LT-B serum IgG and faecal IgA to that produced in mice gavaged with bacterial LT-B. Mice were fed three weekly doses of 5 g tuber tissue containing either 20 or 50 micrograms LT-B, or gavaged weekly with 5 micrograms of LT-B from recombinant E. coli. One week after the third dose, mice immunized with potato LT-B had higher levels of serum and mucosal anti-LT-B than those gavaged with bacterial LT-B. Mice were challenged by oral administration of 25 micrograms LT, and protection assessed by comparing the gut/carcass mass ratios. Although none of the mice were completely protected, the higher dose potato vaccine compared favourably with the bacterial vaccine. These findings show that an edible vaccine against E. coli LT-B is feasible.     

Delta9-tetrahydrocannabinol suppresses macrophage costimulation by decreasing heat-stable antigen expression

Delta9-tetrahydrocannabinol (THC) suppresses several immunologic functions of macrophages. The costimulatory activity of a THC-exposed macrophage hybridoma was investigated by its ability to elicit interleukin-2 secretion by a helper T cell hybridoma activated with immobilized monoclonal anti-CD3 antibody. THC added at culture initiation inhibited the T cell response in a dose-dependent manner. When the macrophages were fixed with paraformaldehyde before culture, THC had no effect on T cell stimulation. However, macrophages, which were preincubated with THC and then fixed, were impaired in delivering costimulatory signals to T cells cultured without THC. The drug's inhibitory effect on macrophage costimulatory activity was reversible. THC exposure also decreased macrophage expression of heat-stable antigen (HSA). Antibody blocking experiments showed that HSA expressed on the macrophages provided an important costimulatory signal, whereas B7-1 and B7-2 molecules had a minor role. Treatment of the macrophages with phosphatidylinositol-specific phospholipase C cleaved HSA, but not the transmembrane B7 molecules, from the cell surface. Similar to THC, enzyme treatment significantly diminished macrophage costimulatory activity, which was also reversible. After drug or enzyme removal, HSA expression returned to the control level by 4 h. Therefore, THC suppresses macrophage costimulatory activity by diminishing cell surface expression of HSA.     

A critical evaluation of several alcohol screening instruments using the CIDI-SAM as a criterion measure

Four alcohol screening instruments (the AUDIT, CAGE, MAST, and Svanum's scale) were administered to a sample of 306 undergraduate students at a Midwestern university and were compared with regard to several test characteristics, using the alcohol section of the CIDI-SAM (DSM-IV version) as the criterion measure. The performance of these instruments was evaluated using two subsets of subjects: (1) students who currently met diagnostic criteria for alcohol dependence (n = 35); and (2) students who met diagnostic criteria for alcohol dependence in the past and/or at present (i.e., lifetime diagnosis; n = 50). The AUDIT performed significantly better than the other three instruments in identifying students who were currently alcohol dependent, providing a moderate degree of clinical utility with this group. The four instruments did not differ significantly in their ability to identify students with a lifetime diagnosis; each measure provided only a modest degree of clinical utility with this group.     

A note on surface waves in anisotropic media

Summary An examination of possible forms of traction free surface wave in anisotropic elastic materials is undertaken. The results yield some interesting features of a certain arbitrariness which exists in displacement waves on a traction free surface in anisotropic media.     

Relationship between lead mining and blood lead levels in children

The authors studied blood lead levels of 226 randomly selected children, aged 6-92 mo, who lived in either a lead-mining area or a nonmining area, and 69 controls. The authors sought to determine to what extent mining activities contributed to blood lead levels in the children. The mean blood lead levels in the study and control groups were 6.52 microg/dl and 3.43 microg/dl, respectively. The corresponding proportions of children with elevated blood lead levels were 17% and 3%. Soil and dust lead levels were up to 10 times higher in the study than the control group. Elevated blood lead levels appeared to result from exposure to both lead-mining waste and lead-based paint. Mining waste was the cause of the higher prevalence of elevated blood lead levels in these children.     

A BEM for time dependent infiltration from an irrigation channel

In this paper some two dimensional time dependent infiltration problems are considered. The problems involve infiltration from an irrigation channel into a homogenous soil and a soil which contains an impermeable finite inclusion. The problems are reduced to boundary integral equations which may be solved numerically using established procedures. Numerical results are obtained to provide the distribution of the matric flux potential for some particular impermeable inclusions and a particular channel shape. The results indicate how the distance from the channel influences the speed with which the matric flux potential reaches its steady state value. They also illustrate how the presence of an impermeable inclusion can increase the matric flux potential at points below the surface.     

Theoretical analysis of neutron scattering spectra of4He films on graphite

We compare microscopic calculations of the dynamic structure function of helium films adsorbed to a graphite substrate with neutron scattering data. Starting from a generalized Feynman theory of collective excitations, we include successively, three-phonon interactions, self-energy corrections, and experimental broadening and thereby improve the agreement between theoretical predictions and experiments. The inclusion of three-phonon vertices allows high-lying excited states to decay into lesser energetic ones and thus leads to a natural linewidth. It is shown that the theoretical linewidth of the excitations is typically smaller than the experimental resolution, and that much structure of the spectrum in the neutron scattering data is obscured under a broad plateau between the ripplon and the phonon excitations. This analysis leaves little doubt of the existence of layer-phonons and that the observed shoulder in the dynamic structure function, near the roton minimum, is actually a 2D roton propagating in the inner-most liquid layer.