Showing papers by "United States Department of Energy published in 1992"

Gibberellin Is Required for Flowering in Arabidopsis thaliana under Short Days.

Abstract: Mutants of Arabidopsis thaliana deficient in gibberellin synthesis (ga1-3 and ga1-6), and a gibberellin-insensitive mutant (gai) were compared to the wild-type (WT) Landsberg erecta line for flowering time and leaf number when grown in either short days (SD) or continuous light (CL). The ga1-3 mutant, which is severely defective in ent-kaurene synthesis because it lacks most of the GA1 gene, never flowered in SD unless treated with exogenous gibberellin. After a prolonged period of vegetative growth, this mutant eventually underwent senescence without having produced flower buds. The gai mutant and the “leaky” ga1-6 mutant did flower in SD, but took somewhat longer than WT. All the mutants flowered readily in CL, although the ga1-3 mutant showed some delay. Unlike WT and ga1-3, the gai mutant failed to respond to gibberellin treatment by accelerating flowering in SD. A cold treatment promoted flowering in the WT and gai, but failed to induce flowering in ga1-3. From these results, it appears that gibberellin normally plays a role in initiating flowering of Arabidopsis.

Speciation of mercury and lead compounds by microbore column liquid chromatography-inductively coupled plasma mass spectrometry with direct injection nebulization.

Abstract: Various cationic species of Hg (Hg 2+ , MeHg + , EtHg + , and PhHg + ) and Pb 2+ , (Me) 3 Pb + , and (Et) 3 Pb + ) are separated as ion pairs by reversed-phase liquid chromatography. Lead is detected ≃0.2 pg and Hg at ≃7 pg by inductively coupled plasma mass spectrometry. A direct injection nebulizer minimizes band broadening and yields good sensitivity by injecting all the sample into the plasma

A method to study ``equilibration'' in nucleus-nucleus collisions

Abstract: A method to study “equilibration level” of a system created in high energy nucleus-nucleus collisions is proposed. The method is based on the fact that the correlation between momentum distribution and particle multiplicity observed in nucleon-nucleon interactions can be also measured in nucleus-nucleus collisions. It is argued that the magnitude of the residual correlation can be used as a measure of the system “equilibration level”. The method is effective even when changes of the “equilibration level” do not modify the inclusive distribution. The quantitative estimate of the effect to be measured is given. Finally, questions arising in practical application of the method are discussed.

Supercapacitors based on carbon foams

Abstract: A high energy density capacitor incorporating a variety of carbon foam electrodes is described. The foams, derived from the pyrolysis of resorcinol-formaldehyde and related polymers, are high density (0.1 g/cc-1.0 g/cc) electrically conductive and have high surface areas (400 m2/g-1000 m2/g). Capacitances on the order of several tens of farad per gram of electrodes are achieved. The preferred embodiment capacitor has two cells. In the upper cell (10), a solder-wettable layer (32) and an adhesive metal layer (30) overlie an electrode (22). An electrode separator (40) lies between electrode (22) of the upper cell (10) and electrode (26) of the upper cell (10). Solder-wettable layer (36) and adhesive layer (34) overlie electrode (26). A similar electrode (26) is shown in lower cell (12), with adhesive layer (34) and solder-wettable layer (36) formed thereon. A cell separator (24) lies between electrode (22) of cell (10) and electrode (26) of cell (12).

Elemental speciation by liquid chromatography–inductively coupled plasma mass spectrometry with direct injection nebulization

Abstract: A new version of the direct injection nebulizer (DIN) is used to interface liquid chromatographic (LC) separations with element-selective detection using inductively coupled plasma mass spectrometry (ICP-MS). The DIN injects all of the sample into the ICP and has a dead volume of less than 1 µl. Charged species of arsenic and tin are separated as ion pairs on a micro-scale (1 mm i.d.), packed, reversed-phase column. Detection limits are 0.2–0.6 pg for arsenic and 8–10 pg for tin. For methanol + water eluents, the signal is highest at 25% methanol and stays within 25% of this maximum as the methanol fraction is varied from 20 to 80%. Compared with LC–ICP-MS with conventional nebulizers, the absolute detection limits and chromatographic resolution are substantially superior, and the dependence of analyte signal on solvent composition is somewhat less severe with the DIN.

Pollution abatement expenditures and regional manufacturing activity

Abstract: . Using a sample of 63 SMSAs for the years 1974, 1978, and 1982 I find weak support for the argument that environmental regulations retard economic activity. Regression analysis of the relationship between per unit total and air pollution abatement expenditures in the manufacturing sector of these SMSAs and manufacturing employment and earnings levels reveals that these associations are negative but that the magnitudes are relatively small. For example, 10 percent higher per unit total pollution abatement costs are associated with, on average, 1064 fewer manufacturing workers (0.17 percent of total regional employment) in Sun Belt SMSAs during 1982.

Filtered cathodic arc source

Abstract: A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45° to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles.

Mechanism of nonphotochemical hole burning: Cresyl Violet in polyvinyl alcohol films

Abstract: Polarized nonphotochemical hole-burned spectra of Cresyl Violet in polyvinyl alcohol films are presented for various burn temperatures (TB). For TB = 15 K, but not for TB = 2.2 K, a significant rotation of Cresyl Violet is indicated. The broad, tailing antihole is observed to depend on TB. The quantum efficiency distributions for the zero-phonon hole and pseudo-phonon sideband are quite similar, proving that the phonons created by excitation of the phonon sideband are not important for hole burning. The quantum efficiency is independent of TB over the range studied, 1.6–15 K. Over this range essentially 100% of the zero-phonon lines can be burned. The results show that the standard two-level-system (extrinsic) model for nonphotochemical hole burning is inadequate. The results are discussed in terms of an outside-in hierarchy of configurational relaxation events model [ Chem. Phys.141, 447 ( 1990)] as well as other models.

Theoretical and experimental investigation of cosmogenic radioisotope production in germanium

Abstract: Rates were calculated for the cosmic-ray-induced production of 3 H, 54 Mn, 57 Ni, 57,58 Co, 65,67 Ga, 65 Zn, and 68 Ge in natural germanium using two experimental neutron spectra from the literature. Reaction excitation functions were computed with a nuclear spallation code. Experimental production rates of 54 Mn, 57,58 Co, 65 Zn, 67 Ga and 68 Ge were derived from background spectra of natural isotopic abundance germanium detectors. The rate for 57 Co was also derived from data taken with a detector fabricated from germanium isotopically enriched to 86% 76 Ge and ∼14% 74 Ge . The calculated and experimental data are in agreement within a factor of two and in many cases within 30%.

Procedures for Sampling Deep Subsurface Microbial Communities in Unconsolidated Sediments

Abstract: A corehole sampling project utilizing a wireline coring system provided sediment samples for microbiological characterization from deep unconsolidated sediments. Sampling tools were developed or modified to minimize contamination during sample acquisition and to facilitate stringent decontamination requirements. Quality assurance procedures, including the use of tracers, were implemented to minimize and quantify contamination from drilling hardware, drilling fluids and sample processing. Tracers included microspheres, potassium bromide, rhodamine dye, and perfluorocarbons, which enabled the detection and measurement of 1mg of drilling fluid per kg of sediment. In addition, sample processing was performed on-site in an anaerobic chamber to prevent exposure of the subsurface materials to atmospheric oxygen concentrations. Sediment samples were then disbursed to investigators at National Laboratories and universities funded through the Department of Energy Subsurface Science Microbiology Program for microbiological characterization. Results of these efforts demonstrated that representative subsurface samples were collected and disbursed.

Optical Considerations for Infrared Reflection Spectroscopic Analysis in the C-H Stretching Region of Monolayer Films at an Aqueous/Metal Interface

Abstract: This paper describes the optical analysis, construction, testing, and application of a cell for measuring in situ IR reflection spectra in the C-H stretching region of monolayer films of long-chain alkanethiolates on evaporated Au films beneath a thin overlayer (∼1 μm) of aqueous solution. The cell facilitates the interchange of sample (monolayer-coated) and reference substrates—a major improvement over previous designs. This allows the acquisition of an IR reflection spectrum of a monolayer without the application of electrochemical or polarization-modulation methods. The optical properties of the cell are analyzed within the context of classical electromagnetic theory; the effects of angle of incidence, solution layer thickness, and solution composition (H2O and D2,O) and the refractive indices of the IR-transparent window material on the observed spectrum are specifically examined. Calculations of both the mean-square electric fields and the reflection spectra for a monolayer of octadecanethiolate on Au are presented. From these results, conditions to achieve high surface detectability are identified, and optically induced alterations in the intensities and shapes of the monolayer spectrum are delineated. Spectra for the same monolayer are measured to test these predictions as well as to assess the practical limitations of the experimental technique.

High voltage dc-dc converter with dynamic voltage regulation and decoupling during load-generated arcs

Abstract: A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules.

Remarks on the modeling of fluidized systems

Abstract: In the equations governing the flow of fluidized systems, one often comes across a modulus G(e), referred to as the modulus of elasticity. We address the issue that values used for G(e) are orders of magnitude apart and point out that such a modulus, derived and used in the manner of Ettehadieh et al. (1984) and Gidaspow (1986), need to be central to the theory of fluidization

Methyl formate hydrogenolysis for low-temperature methanol synthesis

Abstract: The hydrogenolysis of methyl formate to methanol was studied in a liquid-phase reactor using a heterogeneous copper catalyst. This reaction is part of a process to produce methanol from synthesis gas starting with the carbonylation of methanol to methyl formate. Raney copper was compared with copper-chromite for hydrogenolysis activity at 110 to 160°C. The inhibition of the hydrogenolysis reaction by carbon monoxide was found to be lower at higher temperatures. A rate equation was derived to include this temperature dependence. Also, carbon monoxide made by a side reaction, the decarbonylation of methyl formate, was carefully measured and shown to account for only 1 to 2% of the total methanol produced at these temperatures.

Leaching of Pyrites of Various Reactivities by Thiobacillus ferrooxidans.

Abstract: Wide variations were found in the rate of chemical and microbiological leaching of iron from pyritic materials from various sources. Thiobacillus ferrooxidans accelerated leaching of iron from all of the pyritic materials tested in shake flask suspensions at loadings of 0.4% (wt/vol) pulp density. The most chemically reactive pyrites exhibited the fastest bioleaching rates. However, at 2.0% pulp density, a delay in onset of bioleaching occurred with two of the pyrites derived from coal sources. T. ferrooxidans was unable to oxidize the most chemically reactive pyrite at 2.0% pulp density. No inhibition of pyrite oxidation by T. ferrooxidans occurred with mineral pyrite at 2.0% pulp density. Experiments with the most chemically reactive pyrite indicated that the leachates from the material were not inhibitory to iron oxidation by T. ferrooxidans.