Torsion and bending of nucleic acids studied by subnanosecond time-resolved fluorescence depolarization of intercalated dyes

Subnanosecond time‐resolved fluorescence depolarization has been used to monitor the reorientation of ethidium bromide intercalated in native DNA, synthetic polynucleotide complexes, and in supercoiled plasmid DNA. The fluorescence polarization anisotropy was successfully analyzed with an elastic model of DNA dynamics, including both torsion and bending, which yielded an accurate value for the torsional rigidity of the different DNA samples. The dependence of the torsional rigidity on the base sequence, helical structure, and tertiary structure was experimentally observed. The magnitude of the polyelectrolyte contribution to the torsional rigidity of DNA was measured over a wide range of ionic strength, and compared with polyelectrolyte theories for the persistence length. We also observed a rapid initial reorientation of the intercalated ethidium which had a much smaller amplitude in RNA than in DNA

Large wind turbines: A utility option for the generation of electricity

The wind resource is such that wind energy generation has the potential to save 6-7 quads of energy nationally. Thus, the Federal Government is sponsoring and encouraging the development of cost effective and reliable wind turbines. One element of the Federal Wind Energy Programs, Large Horizontal Axis Wind Turbine Development, is managed by the NASA Lewis Research Center for the Department of Energy. There are several ongoing wind system development projects oriented primarily toward utility application within this program element. In addition, a comprehensive technology program supporting the wind turbine development projects is being conducted. An overview is presented of the NASA activities with emphasis on application of large wind turbines for generation of electricity by utility systems

Large wind turbines: A utility option for the generation of electricity

The economic and technical potential of wind energy in the United States is discussed. Particular attention is given to the status of wind turbine operational experience as well as the environmental posture of the technology

Time-resolved spectroscopy of macromolecules: Effect of helical structure on the torsional dynamics of DNA and RNA

The torsional rigidity of DNA and RNA is measured via the fluorescence depolarization technique

Effect of Corn Processing and Reconstitution in High Grain Diets on Feedlot Performance and Carcass Characteristics of Steers and Heifers

A 167-day feedlot trial was conducted to examine the effects of corn processing and reconstitution on growth performance and carcass characteristics of feedlot cattle. Initial weights of the continental cross steers (n = 95) and heifers (n =63) were 690 and 680 Ib, respectively. Diets were 84.5% corn, 7.0% ground grass hay, 4.9% soybean meal, and 3.6% liquid supplement. The grain component of the diet was either dry whole corn (WC), dry rolled corn (RC), corn reconstituted at least 12 h before rolling (RRC), or corn reconstituted with a commercial surfactant3 at least 12 hours before rolling (CRC). Monensin and tylosin were included at 26.9 and 11 .O g/ton, respectively. Dry matter content of the WC, RC, RRC, and CRC diets were 85.62, 85.03, 80.98, and 80.96%, respectively. Dietary treatment had no effect on the feedlot performance of the steers or heifers. Yield grade (YG) was lower (P= .05) for CRC than for RRC cattle (2.96 vs 3.27). Kidney pelvic and heart fat (KPH) was lower (Pc.05) for RC (2.30%) and CRC (2.29%) than for WC (2.48%) and RRC (2.56%) cattle. KPH and YG were the only measured variable affected by dietary treatment indicating little advantage to any of the corn processing methods tested

Grain Sources and Roughage Levels for Limited Feeding Backgrounding Programs

The effects of grain source and roughage level in limited intake feeding programs were evaluated in 622-lb steer calves. Supplemented diets were based on high moisture ear corn (HMEC), whole shelled corn (WSC) + hay to provide similar NDF to the HMEC diet, HMEC diet containing 10% hay and the WSC + hay diet formulated to contain NDF similar to HMEC + hay. Steer calves were blocked by weight and fed to achieve 2.2 Ib ADG for a 52-day period. Steers fed HMEC had higher (P\u3c.01) ADG and lower (P\u3c.01) feed/gain than WSC fed steers. Low crude protein in the hay source caused lower (P\u3c.01) crude protein in WSC diets. Lower crude protein intake could have limited steer growth. NE utilization appeared more efficient (P\u3c.05) for heavy weight block steers, reflecting NRC equation low sensitivity to modest differences in frame size. Roughage level did not affect performance and did not interact with grain source

Substitution of Rolled Barley for Whole Shelled Corn in Finishing Diets for Steers

Rolled barley was substituted for 0, 25, 50, 75 or 100% of the whole shelled corn in finishing diets fed to steers for 84 days. Increasing barley substitution resulted in a linear (P=.12) decrease in ADG and a quadratic (P\u3c.05) decrease in DM1 with no effect on feed conversion. At the termination of the study, barley substitution caused a linear reduction in carcass weight (P\u3c.01) and dressing percent (P\u3c.01). The 100% substitution of barley for corn reduced (Pc.05) the percentage of carcasses grading choice. Dietary net energy values calculated from steer weights, gain and feed intake increased linearly (P\u3c.10) as barley content of the diets increased, possibly reflecting positive associative effects. Published energy values for barley may not be suitable for least cost pricing in all feeding situations

Effect of Corn Processing and Reconstitution on the Digestibility of High Grain Diets

Twelve steers (body weight 955 Ib + 37) were allotted to a 4 x 4 Latin square design digestion trial to examine the effects of corn processing on feed utilization. The grain component of the diet was either dry whole corn (WC), dry rolled corn (RC), corn reconstituted 12 hours before rolling (RRC), or corn reconstituted with a commercial surfactant3 12 hours before rolling (CRC). Dry matter content of the WC, RC, RRC, and CRC diets were 87.91, 87.30, 82.1 9, and 82.14%, respectively. Treatment had no effect on the digestibilities of dry matter (71.00% ± 1.57), organic matter (72.22% ± 1.531, crude protein (57.54% ± 1.66), neutral detergent fiber (52.68% ± 3.071, or starch (85.67% + .98). Neutral detergent fiber digestion was affected by period, but this was not related to bulk density of the corn which ranged from 43 to 56 Ib/bu over periods. Processing did not affect dry matter intake (21.76 Ib/day ± .41), although reconstitution depressed (P \u3c .01) dry matter intake as a percentage of body weight (2.19, 2.24, 2.1 1, and 2.1496, respectively). To quantify differences in particle size, processed grain samples were separated with #5, 7, 10, and 18 mesh sieves. Mean percentages retained on a #5 mesh sieve were 85.26, 58.74, 84.27, and 83.57% for WC, RC, RRC, and CRC, respectively. Subsequent separated fractions of WC and the reconstituted treatments were similar

Implant Combinations and Reimplanting Strategies for Yearling Steers Fed High Concentrate Diets

Crossbred yearling steers were used to determine the relative efficacy of specific anabolic implant combinations and sequences on feedlot performance and carcass traits. Steers were fed a high concentrate finishing diet for 112 days. lmplanting was done on days 1 and 42 of the feeding period. lmplanting improved (P \u3c .05) average daily gain (ADG) 22% and feed efficiency 15%. Implant treatment generally increased dry matter intake. Lmplanting increased (P\u3c.05) the rib eye area of carcasses 6.5% and tended to cause a reduction in percentage choice carcasses. The percentage of abscessed implants ranged from \u3c 1 % to 10%, depending on the type of implant used even though implant needles were disinfected between each use

Effect of many-body interactions on the solid-liquid phase-behavior of charge-stabilized colloidal suspensions

The solid-liquid phase-diagram of charge-stabilized colloidal suspensions is calculated using a technique that combines a continuous Poisson-Boltzmann description for the microscopic electrolyte ions with a molecular-dynamics simulation for the macroionic colloidal spheres. While correlations between the microions are neglected in this approach, many-body interactions between the colloids are fully included. The solid-liquid transition is determined at a high colloid volume fraction where many-body interactions are expected to be strong. With a view to the Derjaguin-Landau-Verwey-Overbeek theory predicting that colloids interact via Yukawa pair-potentials, we compare our results with the phase diagram of a simple Yukawa liquid. Good agreement is found at high salt conditions, while at low ionic strength considerable deviations are observed. By calculating effective colloid-colloid pair-interactions it is demonstrated that these differences are due to many-body interactions. We suggest a density-dependent pair-potential in the form of a truncated Yukawa potential, and show that it offers a considerably improved description of the solid-liquid phase-behavior of concentrated colloidal suspensions