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At least 163 records · Page 9
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DOE OSTI2024

The stem cell-type transcriptome of bioenergy sorghum reveals the spatial regulation of secondary cell wall networks

Stems accumulate high levels of sucrose that could be used to synthesize bioethanol and useful biopolymers if information about stem cell-type gene expression and regulation was available to enable engineering. To obtain this information, Laser Capture Microdissection (LCM) was used to isolate and collect transcriptome profiles from five major cell types that are present in stems of the sweet sorghum Wray. Transcriptome analysis identified genes with cell-type specific and cell-preferred expression patterns that reflect the distinct metabolic, transport, and regulatory functions of each cell type.

cell specificity↗
NASA NTRS1971

Environmental microbiology as related to planetary quarantine

The experiments carried out to determine the effects of temperature and relative humidity on the survival rate of Bacillus subtillis var. niger spores are reported. The experiments were conducted in environmental chambers at temperatures of 75 and 90 C. Data are also included on the survival characteristics of the spores suspended in sucrose solutions at 90 C with water activities of 0.99, 0.9, and 0.85

Pflug, I. J.↗
NASA NTRS1972

Mechanisms of deterioration of nutrients phase 1

Experimental methods are studied by which freeze-dried foods of improved quality are produced. Considered are: (1) Factors effecting the loss of butanol from frozen aqueous food solutions during storage; (2) a freeze-drying microscope system for observing solidification processes in organic mixtures and aqueous inorganic salt solutions; (3) browning of high quality freeze-dried foods with minimal organoleptic and nutritional detoriation; (4) retention of PVP-n-propanol in freeze-dried food models; and (5) effects of freezing rate and sucrose immersion on taste and texture of freeze-dried apple slices.

Karel, M.↗
NASA NTRS1972

Environmental microbiology as related to planetary quarantine

The survival of Bacillus subtilis var. niger spores suspended in solutions of sucrose and glycerol at calculated water activities and varying temperatures was studied. The overall results indicated that as the water activity of the liquid decreased from .99 to .85, the heat resistance of the spores increased. The nature of the substance controlling the water activity, and the history of the spores prior to treatment also had an affect on their heat resistance.

Pflug, I. J.↗
NASA NTRS1974

Reduction of blood serum cholesterol

By feeding a human subject as the sole source of sustenance a defined diet wherein the carbohydrate consists substantially entirely of glucose, maltose or a polysaccharide of glucose, the blood serum cholesterol level of the human subject is substantially reduced. If 25 percent of the carbohydrate is subsequently supplied in the form of sucrose, an immediate increase from the reduced level is observed. The remainder of the defined diet normally includes a source of amino acids, such as protein or a protein hydrolysate, vitamins, minerals and a source of essential fatty acid.

Winitz, M.↗
NASA NTRS1974

Arthrobacter globiformis and its bacteriophage in soil

An attempt was made to correlate bacteriophages for Arthrobacter globiformis with soils containing that bacterium. The phages were not detected unless the soil was nutritionally amended (with glucose or sucrose) and incubated for several days. Phage was continuously produced after amendment without the addition of host Arthrobacter. These results indicate that the bacteriophage is present in a masked state and that the bacteria are present in an insensitive form which becomes sensitive after addition of nutrient.

Casida, L. E., Jr.↗
NASA NTRS1975

Diffusion in mixed solvents. II - The heat of mixing parameter

Correlation of second-order rate constants for many reactions involving electron transfer between organic molecules, solvated electron reactions, iodine diffusion coefficients, and triplet state electron transfer reactions has been made with the heat of mixing parameter (HMP) for the aqueous binary solvent systems. The aqueous binary solvents studied are those containing methanol or ethanol (type I solvent); 1-propanol or tert-butyl alcohol (type II solvent); or sucrose or glycerol (type III solvent). A plot of the HMP vs. the diffusion parameter for each reaction yields superimposable curves for these reactions in a particular solvent mixture over the entire solvent mixture range, irrespective of the value of the reaction's rate constant or diffusion coefficient in water.

Carapellucci, P. A.↗
NASA NTRS1975

Diffusion in mixed solvents - On the viscosity question

Linear plots of reaction rate vs reciprocal of solvent viscosity are generally used as the classifying criteria for diffusion controlled reactions in fluid solutions and to determine reaction mechanisms in mixed hydroxylic solvents like glycerol and water. This paper presents data which shows that the above-mentioned criteria are insufficient in many cases where nonideal mixed solvent systems are used to increase solvent viscosity. Data correlations suggest that the excess functions determine the variation in reaction rate constants. Kinetic parameters are presented for sucrose-water and methanol-water solvent systems for a reaction involving Fe(CN)6 and zinc uroporphyrin.

Carapellucci, P. A.↗
NASA NTRS1983

Ribulose 1,5-bisphosphate carboxylase and phosphoribulokinase in Prochloron

Ribulose 1,5-bisphosphate (RuBP) carboxylase and phosphoribulokinase, enzymes in the reductive pentose-phosphate cycle, were measured in cell-free extracts of Prochloran didemni. The partial purification and characterization of RuBP carboxylase were described. Prochloron RuBP carboxylase, when purified by isopycnic centrifugation in reoriented linear 0.2 to 0.8 M sucrose gradients, sedimented to a position which corresponded to that of the 520,000-dalton spinach enzyme. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that the Prochloron enzyme was composed of large and small subunits (MW = 57,500 and 18,800). Though results established that the enzymes RuBP carboxylase and phosphoribulokinase were present in levels comparable to other CO2-fixing microorganisms, it was suggested that other enzymes in the Calvin cycle limit growth or that additional enzymic insufficiencies exist.

Berhow, M. A.↗
NASA NTRS1985

The use of moments of momentum to account for crystal habits

A three-step theory of crystal growth is proposed which involves first an association of molecules or ions in solution to form an impinging growth unit, then second the orientation of this unit prior to its impact on the surface of a crystal, and finally the attachment of this unit to the crystal face. From this theory the habit of a crystal is dependent upon the moments of momentum of the impinging growth unit. The results of sample calculations are presented or sodium chloride, succinic acid, sucrose, and chromium boride. The faces predicted by this proposed theory are compared with those predicted by other, energy-based calculations and with those experimentally observed. The proposed theory suggests alternative strategies for crystallization and habit modification which may be of technological importance. Listings of the two computer programs that were used are provided.

Barber, P. G.↗
NASA NTRS1985

Development anmd testing of electrophoresis solutions. Task I.1: Development of optimal buffer system

Two buffers were explored for testing: low ionic strength electrophoresis buffer with and without density gradient material. It was found that the electrophoresis routine was better tolerated when Ficoll was present. The results of a viability study of primary human fetal kidney (HFK-1) cells at the first passage are shown. Cell strain HFK-1 was used in several experiments at the first and second passage. The HFK consisted mainly of fibroblasts, and HFK-1 has a high epithelioid cell content. The chromosomes of HFK were examined and found to be euploid. The stock medium for cell electrophoresis is described. In this solution density gradient solutes such as sucrose and Ficoll are dissolved to bring the osmolarity to 0.30. Its ionic strength is less than 0.01M, and its conductivity is usually 0.0011 mho/cm. Methods for viability determination included direct microscopic counting of the percent cells attached and spread within 24 hr of plating test cultures or electrophoretically separated fractions. The Cytograf viability assay concept was tested, and shown that blue stained cells scatter less light into the 0.8 to 3.3 deg angular interval than do unstained cells.

Source record↗
NASA NTRS1987

Microwave dielectric behavior of vegetation material

The microwave dielectric behavior of vegetation was examined through the development of theoretical models involving dielectric dispersion by both bound and free water and supported by extensive dielectric measurements conducted over a wide range of conditions. The experimental data were acquired using an open-ended coaxial probe that was developed for sensing the dielectric constant of thin layers of materials, such as leaves, from measurements of the complex reflection coefficient using a network analyzer. The probe system was successfully used to record the spectral variation of the dielectric constant over a wide frequency range extending from 0.5 to 20.4 GHz at numerous temperatures between -40 to +40 C. The vegetation samples were measured over a wide range of moisture conditions. To model the dielectric spectrum of the bound water component of the water included in vegetation, dielectric measurements were made for several sucrose-water solutions as analogs for the situation in vegetation. The results were used in conjunction with the experimental data for leaves to determine some of the constant coefficients in the theoretical models. Two models, both of which provide good fit to the data, are proposed.

Elrayes, Mohamed A.↗
NASA NTRS1988

Preliminary observations of the effect of solutal convection on crystal morphology

Studies to examine the effect of solutal convection on crystal morphology using sucrose as a model system were initiated. Aspect ratios, defined as the width of the 100-plane-oriented face over the width of the 001-plane-oriented face, were determined for oriented crystals which were grown with either the 001-oriented or the 100-oriented face perpendicular to the convective flow. The dependence of the crystal morphology on orientation is much greater for crystals grown with one face occluded than for crystals grown suspended in solution. Many factors appear to interact in a complex fashion to influence crystal morphology.

Broom, M. Beth H.↗
NASA NTRS1989

Investigations on gel forming media use in low gravity bioseparations research

Research on gelling media and conditions suitable for the preservation of the spatial configuration of cell suspensions and macromolecular solutions after separation in free fluid during low gravity experiments is presented. The examples studied included free electrophoresis of cells in a cylindrical column and two-phase aqueous polymer separation. Microgravity electrophoresis experiments were simulated by separating model cell types (animal or human) in a vertical density gradient containing low-conductivity buffer, 1.7-6.5 percent Ficoll, 6.8-5.0 percent sucrose, and 1 percent SeaPrep low-melting temperature agarose. Upon cooling, a gel formed in the column and cells could be captured at the forming locations. Two-phase extraction experiments were simulated using two-polymer solutions in which phase separation occurs in normal saline at temperatures compatible with cell viability and in which one or both phases form a gel upon cooling. Suitable polymers included commercial agaroses (1-2 percent), maltodextrin (5-7 percent), and gelatin (5-20 percent).

Todd, Paul↗
NASA NTRS1990

Flow measurements in a model of the mildly curved femoral artery of man

The effects of curvature on the flow rate near the wall in the vicinity of the mildly curved femoral artery of man, and on the pressure distributions along the curved segment, were investigated using glass and tygon flow models constructed to conform to the shape of the femoral angiogram of a human subject. The test fluid was 33 percent aqueous sucrose. Steady flow observations, made using a dye flow visualization system, revealed a flow pattern like that observed in coiled pipes. A double helical type flow was found to develop, with converging streamlines in the wall vicinity from the upper and lower plane of curvature merging asymptotically along the inner curvature in a stable manner. Pressure measurements for steady flow revealed progressively larger pressure drops with distance along the entrance region of the curved segment, relative to that for a straight lumen.

Back, L. H.↗