Long-term retention of ice-nucleating active Pseudomonas fluorescens by overwintering colorado potato beetles

Ice nucleating-active Pseudomonas fluorescens F264C was fed to Colorado potato beetles to determine bacterial retentioin in the beetle gut and its effect on the cold hardiness of this insect pest. The bacrterium was present in beetles recovered after overwintering in the field, seven months after their exposure to P. fluorescens. Retention was evident not only in the detection of the P. fluorescens ice nucleating gene, inaW, in bacterial cultures from beetle guts but also in the elevated supercooling points of some treated beetles.     

Breakdown of stabilization of atoms interacting with intense, high-frequency laser pulses

An analysis of the influence of the magnetic field of an intense, high-frequency laser pulse on the stabilization of an atomic system is presented. We demonstrate that at relatively modest intensities the magnetic field can significantly alter the dynamics of the system. In particular, a breakdown of stabilization occurs, thereby restricting the intensity regime in which the atom is relatively stable against ionization. Counterpropagating pulses do not negate the detrimental effects of the magnetic field. We compare our quantum mechanical results with classical Monte Carlo simulations.     

The adsorption of C6H5Cl on Si(111)7 × 7 studied by STM

The adsorption of chlorobenzene on Si(111)7 × 7 at room temperature was studied by scanning tunneling microscopy (STM). Selective chemisorption was observed at different adatom sites. It was found that the center adatoms were more reactive than the corner adatoms, and the faulted half of the unit cell was more reactive than the unfaulted. The mechanism is discussed in terms of the electronic and atomic structures in Si(111)7 × 7. Both preferences indicate that chlorobenzene was present initially in a mobile precursor state.     

Diffusion and solubility of methane in polyisobutylene

Diffusion coefficients and solubilities of methane in polyisobutylene have been measured at four temperatures between 102 and 188°C. in the pressure range 23–341 atm. Diffusion coefficients extrapolated to atmospheric pressure range from 1.72 × 10^?6 cm.²/sec. at 102°C. to 1.5 × 10^?5 cm.²/sec. at 188°C. corresponding to an activation energy for diffusion of 8.7 ± 0.4 kcal./mole. Solubilities are small, about one molecule of methane for every forty carbon atoms in the polyisobutylene at 300 atm. partial pressure of methane. Solubilities vary little with temperature, but show an apparent minimum between 127 and 188°C. With improved methods of data analysis, diffusion coefficients and solubilities have been recalculated from previously reported studies on nitrogen in branched polyethylene and methane in branched polyethylene, linear polyethylene, and polystyrene. Recalculated diffusion coefficients are essentially the same as those reported previously, but the recalculated solubilities are decreased from 2 to 30%. The solubilities of all five systems show strong deviations from Henry's law, i.e., increases in partial pressure of methane and nitrogen with respect to solubility exceed linearity. The partial pressure (or fugacity)—solubility data may be interpreted in terms of a sorption model in which sorbed molecules are accommodated in widely dispersed, unoccupied volumes or sites in the polymer. An almost equivalent, solution model in which the first sorbed molecules to enter the polymer are accommodated to a large extent in existing volumes in the polymer, with successively sorbed molecules swelling the polymer to a greater extent (i.e., partial molal volume of sorbed molecules, V ₁, increasing with concentration) can also account for these data.     

The estimation of leucine aminopeptidase produced by molting nematodes with labeled leucinamide as substrate

Leucine aminopeptidase activity was measured using l-[U-¹⁴C]leucinamide as substrate. The leucine freed by hydrolysis was separated by high voltage electrophoresis and estimated in a scintillation counter. The method was especially useful for studying the production of LAP during the molting of infective juveniles of the nematodes, H. contortus, because activity could be measured without purifying or concentrating the enzyme.     

History of Polymer Education-USA

Prior to 1940 there was little or no education directed toward polymer chemistry. With the contributions of Carothers and others that transformed the practice of polymers into a science-and the leadership of Herman Mark and others in formal graduate and postgraduate education-polymer education took root but rapid expansion and general acceptance by more traditionally oriented academic institutions was slowed by many barriers. Only since 1974 has there been a concerted effort to include education in the basic concepts of polymer chemistry into the undergraduate curriculum. Emphasis is on the development of polymer education in the United States.     

Polyethylene glycol in copper electrodeposition onto a rotating disk electrode

Many of the proprietary additive formulations that have been proposed to control the properties of metal electrodeposits include water soluble macromolecules. Among these are the hydrodynamically interesting polyethylene glycols ‘Polyox’. In the course of a rotating disk electrode study of the effects of additives in copper electrodeposition the present authors had cause to try the effects of low concentrations of Polyox in an acid copper sulphate plating solution. In the presence of an essential trace of chloride ion Polyox very strongly inhibited deposition below a critical overpotential at which current density rises extremely rapidly with increasing overpotential. These results suggest that below the critical overpotential chloride ions hold a film of Polyox onto the electrode surface and may also give the film some lateral cohesion. The film may be a Polyox-cuprous chloride complex. Striking spiral patterns form at the critical overpotential. Their characteristics are explained as the consequences of electrodeposition on a surface containing submicroscopic protrusions and depressions in conditions where current density increases very rapidly with potential.