Lipopeptide phytotoxins produced by Pseudomonas syringae pv. syringae: comparison of the biosurfactant and ion channel-forming activities of syringopeptin and syringomycin

The maturational status of Adelta and C-fibers in the fetal rat spinal cord was examined using formalin-induced c-fos expression as a marker for neuronal activities. Awake 19-, 20-, and 21-day fetuses (FD) were injected ex utero with 5 microl of 10% formalin either into the ventral aspect of the forepaw or the hindpaw. FD 19 fetuses showed little response to the injection, but with increasing age, the fetuses exhibited more specific behaviors following injury of the paw. By FD 21, fetuses treated with formalin injection showed body curls and twitches, mouth opening, face wiping, and withdrawal of the injected paw. The anatomical data paralleled that of behavior; FD 19 animals expressed a small number of Fos labeled nuclei following the formalin injection that was not statistically different from control animals. The formalin-induced increase in Fos staining was first observed at FD 20 with a large increase in the number of Fos labeled cell occurring between FD 20 and 21. By FD 21, the pattern of Fos stained nuclei resembled that found in neonatal rats. There was constitutive bilateral staining in all untreated, saline and formalin injected fetuses that is unique to prenatal animals. Formalin treated fetuses showed constitutive level of staining in addition to the increase in the c-fos expression caused by formalin. We have thus demonstrated that, as indexed both by behavioral response and by Fos immunoreactivity, rat fetuses are capable of transmitting and responding to noxious input before birth.     

Dynamics of cyanide binding to ferrous Scapharca inaequivalvis homodimeric hemoglobin

Flash photolysis experiments have been carried out for the first time on a hemoglobin ferrous cyanide adduct with an 8 ns laser pulse. A 95% nonexponential rebinding process occurs within 2 micros after full photolysis in ferrous cyanide dimeric Scapharca inaequivalvis hemoglobin (HbI), indicating that once photolyzed the cyanide anion is not able to escape from the protein matrix and rebinds to the heme iron. The resonance Raman spectrum of the 10 ns photoproduct is identical to that of the fully relaxed deoxy derivative, indicating that in the ferrous cyanide HbI adduct protein relaxation occurs within 10 ns after photolysis. This behavior is at variance with that of the carbonmonoxy HbI derivative in which very little geminate rebinding is observed and the photoproduct relaxes with a lifetime of 1 micros. The fast relaxation of the cyanide HbI photoproduct can be accounted for by the small perturbation of the heme structure induced by cyanide binding to ferrous HbI. This is consistent with a deoxy-like conformation of the HbI ferrous cyanide adduct and implies that the pathway for relaxation involves only minor local rearrangements of the heme moiety. Photolysis experiments carried out on ferrous cyanide horse myoglobin, which can be saturated only partially, show a qualitatively similar behavior in ligand rebinding, indicating that the geminate process of the cyanide anion is a general phenomenon in hemoproteins.     

Evaluation of a robust, diimide-based, porous organic polymer (POP) as a high-capacity sorbent for representative chemical threats

A previously described porous organic polymer (NU-POP-1) was evaluated against four representative chemical threats: ammonia, cyanogen chloride, sulfur dioxide, and octane. Ammonia, cyanogen chloride, and sulfur dioxide are examples of toxic industrial chemicals (TICs) spanning the range from highly basic to strong-acid forming substances, while octane is used to assess physical adsorption capacity. Experiments were carried out using a microbreakthrough test apparatus, which measures the adsorption capacity at saturation and gives an indication of the strength of adsorption. The NU-POP-1 material exhibited substantial removal capabilities against the majority of the toxic chemicals, with capacities as high as or better than an activated, impregnated carbon. The ability to remove the highly volatile toxic chemicals ammonia and cyanogen chloride was intriguing, as these chemicals typically require reactive moieities for removal. The present work presents a benchmark for toxic chemical removal, and future work will focus on incorporating functional groups targeting the toxic chemicals of interest.     

Effect of Coal Type and Residence Time on the Submicron Aerosol Distribution from Pulverized Coal Combustion

Three types of pulverized coal were burned in a laboratory furnace under various combustion configurations. Pulverized samples of Utah bituminous, Beulah (North Dakota) lignite, and Texas lignite coals were burned at a rate of 2.5 kg/hr in a laboratory furnace. Aerosol size distributions were measured at various positions within the convection section, and temperature and gas compositions were measured throughout. The evolution of the submicron particle size distribution within the convection section for the three coals was similar, although the location of the initial particle mode at the convection section inlet varied with coal type. While staged combustion of Utah bituminous coal had a variable effect on the volume of submicron aerosol produced, staged combustion of the lignites caused a definite increase in the submicron aerosol volume. Vapor enhancement due to a localized reducing atmosphere, which would effect coals of higher ash volatility, is thought to explain this behavior.     

Effect of Processing Parameters on the Morphology of Hydrothermally Derived PbTiO3 Powders

The influence of processing parameters on the growth and morphology of hydrothermally derived lead titanate (PbTiO₃) powders was investigated. PbTiO₃ powder was synthesized by suspending nanocrystalline powders of TiO₂ in aqueous solutions of KOH and Pb(CH₃COO)₂·3H₂O at temperatures ranging from 120° to 200°C. PbTiO₃ growth initiated in the <100> exposing the (001) surfaces and resulting in a faceted platelet morphology. Particle growth proceeded by further nucleation and growth on existing (001) surfaces. Through repeated dissolution and precipitation, the platelet clusters coarsened into larger cuboidal particles. PbTiO₃ particle size was controlled by either inhibiting or promoting dissolution-precipitation. Dissolution-precipitation was inhibited by lowering the KOH concentration or the reaction temperature, or maintaining an excess of lead ions in solution, while it was promoted by increasing the KOH concentration and temperature. Coarsening of PbTiO₃ particles coincided with decreases in the X-ray diffraction (XRD) peak breadth, the asymmetry of l component XRD reflections, and the c -axis length.     

A concept for storing utility-scale electrical energy in the form of latent heat

A concept is introduced here for storing utility-scale electrical energy in the form of latent heat. The storage process utilizes a boiling refrigerant at sub-ambient temperatures to freeze a latent heat storage material using electrically driven compressors. Recovery of the latent heat for electrical generation then uses vapor expansion and condensation which essentially reverses the storage process. Sensible heat storage is incorporated into the cycle to efficiently implement the concept. Both energy storage and generation are carried out under steady flow closed-loop conditions where the T-s diagram is similar to a Rankine cycle. From a thermodynamic perspective, work is supplied to the system while heat is transferred to the surroundings from the latent heat store. The reverse process generates work while using heat supplied by the surroundings. An analysis with expander/compressor isentropic efficiencies and small temperature differentials for the heat transfer processes can give projected round trip efficiencies in the 50–60% range using a common refrigerant. One of the attractive features of this approach is the ability to use different ambient temperatures for storage and generation. Exploiting diurnal temperature differences or sources of low grade heat (50–90 °C) significantly increases the apparent round trip storage efficiency.     

Thin film transmission matrix approach to fourier transform infrared analysis of HgCdTe multilayer heterostructures

The ability to achieve high-yield focal plane arrays from Hg_1−xCd_xTe molecular beam epitaxy material depends strongly on postgrowth wafer analysis. Nondestructive analysis that can determine layer thicknesses as well as alloy compositions is critical in providing run-to-run consistency. In this paper, we incorporate the use of a thin film transmission matrix model to analyze Fourier transform infrared (FTIR) transmission spectra. Our model uses a genetic algorithm along with a multidimensional, nonlinear minimization Nelder-Mead algorithm to determine the composition and thickness of each layer in the measured epitaxial structure. Once a solution has been found, the software is able to predict detector performance such as quantum efficiency and spectral response. We have verified our model by comparing detector spectral data to our predicted spectral data derived from the room-temperature FTIR transmission data. Furthermore, the model can be used to generate design curves for detectors with varying absorber thicknesses and/or different operating temperatures. The consequence of this are reduced cycle times and reduced design variations.