Modelling the distribution of isopropyl N-(3-chlorophenyl) carbamate [CIPC] in box potato stores

Summary A numerical model has been produced to predict the distribution of deposits of the sprout suppressant isopropyl N-(3-chlorophenyl) carbamate [CIPC] in box potato stores. The model considers the movements of the CIPC by forced convection, sedimentation, natural convection and diffusion. Measurements have mostly shown high levels of CIPC on the top of the uppermost box, with levels decreasing towards the floor of the store. The model predicts this pattern and indicates that particle size, the temperature difference between the air inside and around the boxes, and the application rate of the chemical have a large effect on the levels and uniformity of CIPC deposits. Smaller particles (2 μm) can lead to better uniformity of distribution, but they are prone to natural convection effects which are difficult to control and they are slow to deposit which could lead to greater losses from the store.     

Effect of sodium chloride on gluten network formation,dough microstructure and rheology in relation to breadmaking

Sodium chloride (NaCl) is an essential ingredient to control the functional properties of wheat dough and bread quality. This study investigated the effect of NaCl at 0, 1 and 2%, (w/w, flour base) on the gluten network formation during dough development, the dough rheology, and the baking characteristics of two commercial flours containing different levels of protein (9.0 and 13.5%) and with different glutenin-to-gliadin ratios. Examination of the dough structure by confocal microscopy at different stages of mixing show that the gluten network formation was delayed and the formation of elongated fibril protein structure at the end of dough development when NaCl was used. The fibril structure of protein influenced the dough strength, as determined by strain hardening coefficient and hardening index obtained from the large deformation extension measurements. NaCl had a greater effect on enhancing the strength of dough prepared from the low protein flour compared to those from the high protein flour. The effect of NaCl on loaf volume and crumb structure of bread followed a similar trend. These results indicate that the effect of NaCl on dough strength and bread quality may be partially compensated by choosing flour with an appropriate amount and quality of gluten protein.     

Effect of hydrodynamic dispersion on phosphatase reactions in a soil column

Columns of artificially-prepared soil crumbs were perfused with solutions of p-nitrophenyl phosphate and rates of hydrolysis of this substrate as catalyzed by soil phosphatase were measured. Hydrolysis proceeded by a zero-order or by a first-order reaction at high and low concentrations of substrate, respectively. Steady-state concentrations of substrate and products from the columns can be described essentially in terms of plug flow kinetics with but minor corrections for hydrodynamic dispersion. Values of the zero and first-order rate constants corrected for dispersion are 3 and 9 per cent greater, respectively, than those assuming plug flow kinetics. The apparent value of the first-order rate constant is about 70 percent higher than the true value because of electrostatic repulsion between the negatively-charged substrate and the soil particles.     

Identification of a DNA nonhomologous end-joining complex in bacteria

In eukaryotic cells, double-strand breaks (DSBs) in DNA are generally repaired by the pathway of homologous recombination or by DNA nonhomologous end joining (NHEJ). Both pathways have been highly conserved throughout eukaryotic evolution, but no equivalent NHEJ system has been identified in prokaryotes. The NHEJ pathway requires a DNA end-binding component called Ku. We have identified bacterial Ku homologs and show that these proteins retain the biochemical characteristics of the eukaryotic Ku heterodimer. Furthermore, we show that bacterial Ku specifically recruits DNA ligase to DNA ends and stimulates DNA ligation. Loss of these proteins leads to hypersensitivity to ionizing radiation in Bacillus subtilis. These data provide evidence that many bacteria possess a DNA DSB repair apparatus that shares many features with the NHEJ system of eukarya and suggest that this DNA repair pathway arose before the prokaryotic and eukaryotic lineages diverged.     

Condensation of nonequilibrium phases of refractory silicates from the vapor

Silicon monoxide solid was evaporated in a bell jar containing reducing, neutral, or oxidizing atmospheres at pressures of a few torr. The vapor invariably condensed as smoke-sized particles of silicon sesquioxide, Si(2)O(3). The condensation of a solid whose composition differs from that of the parent gas and is apparently the least stable of the three solid species illustrates the importance of specific nucleation effects in the condensation process. This result has significant implications for theories of formation of grains in space.     

Chestnut Blight: Biological Control by Transmissible Hypovirulence in Endothia parasitica

Hypovirulence in Endothia parasitica is caused by a cytoplasmic determinant that is transferred by hyphal anastomosis in host tissue and in culture. Transmission of this determinant affects the virulence of the fungus to the extent that host invasion by previously virulent isolates is limited.     

Suppression of gamma interferon production by inactivated feline leukemia virus

Supernatants from cultures of normal feline lymphocytes stimulated with Staphylococcus enterotoxin A showed antiviral activity, characterized as a gamma-like interferon. With the addition of inactivated feline leukemia virus, markedly less interferon was produced. The reduction in interferon production was not attributable to lowered lymphocyte viability or reduced mitogenic properties of Staphylococcus enterotoxin A and appears to be a direct retroviral effect. This finding may reflect clinically relevant events that may contribute to the development of the feline or human states of acquired immunodeficiency.