Showing papers by "Research Triangle Park published in 1974"

Decay of two-dimensional homogeneous turbulence

Abstract: The decay of two-dimensional, homogeneous, isotropic, incompressible turbulence is investigated both by means of numerical simulation (in spectral as well as in grid-point form), and theoretically by use of the direct-interaction approximation and the test-field model. The calculations cover the range of Reynolds numbers 50 ≤ RL ≤ 100. Comparison of spectral methods with finite-difference methods shows that one of the former with a given resolution is equivalent in accuracy to one of the latter with twice the resolution. The numerical simulations at the larger Reynolds numbers suggest that earlier reported simulations cannot be used in testing inertial-range theories. However, the large-scale features of the flow field appear to be remarkably independent of Reynolds number.The direct-interaction approximation is in satisfactory agreement with simulations in the energy-containing range, but grossly underestimates enstrophy transfer at high wavenumbers. The latter failing is traced to an inability to distinguish between convection and intrinsic distortion of small parcels of fluid. The test-field model on the other hand appears to be in excellent agreement with simulations at all wavenumbers, and for all Reynolds numbers investigated.

A comparison of the distribution and electron acceptor specificities of xanthine oxidase and aldehyde oxidase.

Abstract: 1. 1. Tissue extracts of species from eight animal phyla were assayed for the two closely related enzymes, xanthine oxidase (E.C. 1.2.3.2) and aldehyde oxidase (E.C. 1.2.3.1). 2. 2. Species differences in the levels of aldehyde oxidase activity were much more pronounced than those of xanthine oxidase, although both enzymes were detected throughout much of the animal kingdom and were found to be mainly concentrated in liver and intestine. 3. 3. With aldehyde oxidase from most species, ferricyanide but not NAD+, was an efficient electron acceptor. 4. 4. With xanthine oxidase, three electron acceptor specificity patterns were found among the xanthine oxidases studied. 5. 5. Pattern I [NAD+>ferricyanide>O2] was found with the enzymes from the bony fishes, amphibians, reptiles and birds. 6. 6. Pattern II [ferricyanide>NAD+>O2] was common among the mammals but was also found with a few of the amphibians and reptiles studied. 7. 7. Pattern III [ferricyanide>O2>NAD+] was found only with some mammals, including man.

Pore size of microporous polymer membranes

Abstract: Pore sizes of microporous polymer membranes were determined by the calculation based on the gas permeability of porous media. The gas permeability coefficient K (given by J = K Δp/l, where J is the steady-state gas flux, Δp is the pressure, difference, and l = the thickness of a membrane) for porous membrane can be given generally by where K0 is the Knudsen permeability coefficient, η is the viscosity of the permeant gas, B0 is the geometric factor of a membrane, and Δp is the mean pressure of the gas on both sides of a membrane. From gas permeability measurements which yield the pressure dependence of gas permeability coefficient (expressed as above equation), the mean pore size of the porous membrane can be estimated as where M is the molecular weight of the permeant gas. The validity of this method was examined with various Millipore filters of which nominal pore sizes are known. It was confirmed that the method provided a simple and reliable means of estimating mean pore size of microporous membranes. The method was applied to investigate the influence of factors involved in preparation of microporous polysulfone membranes by coagulation procedure. It was found that the mean pore size of porous polysulfone membrane increases with (1) increasing with casting thickness, (2) increasing temperature of coagulation bath, and (3) decreasing concentration of polymer in casting solution (DMF as solvent). Water flux and water flux decline due to compaction are also examined as a faction of pore size, porosity, and the thickness of membranes.

CO 2 Laser Absorption Coefficients for Determining Ambient Levels of O 3 , NH 3 , and C 2 H 4

Abstract: A carbon dioxide laser source was used to determine absorption coefficients for dilute absorber–air mixtures at wavelengths corresponding to several vibration–rotation lines in each branch of the 00°1–02°0 band at 9.4 μm and the 00°1–10°0 band at 10.4 μm. For all samples the total pressure was 1 atm and the temperature was 300 K; the concentrations ranged from 10 ppm (parts per million by volume) to 357 ppm for NH3 and C2H4, and from 10 ppm to 80 ppm for O3. The absorption coefficients are tabulated, and the use of selected laser lines in monitoring ambient concentrations is discussed.

Production of hydrogen peroxide by wood-rotting fungi in wood and its correlation with weight loss, depolymerization, and pH changes

Abstract: 1. Wood-decay fungi produced H2O2 solely from native substrates in wood. Most basidiomycetes which cause brown-rot of wood produced H2O2 more rapidly on loblolly pine than sweetgum and they produced H2O2 more quickly than white-rot fungi which varied considerably among themselves in formation of the oxidant. 2. Most brown-rot fungi depolymerized wood cellulose extensively at low weight losses and lowered the pH of wood. At these weight losses, white-rot fungi raised the degree of polymerization or depolymerized cellulose slightly and either raised pH of wood or lowered it but a little. 3. Ability to produce H2O2 from glucose in culture was generally correlated well with ability to produce H2O2 in wood for brown-rot fungi. However, exceptions for these and some white-rot fungi suggest that H2O2 may originate from sources other than glucose in wood. 4. Brown-rot fungi produced sufficient H2O2 in 3 days, and the acidic conditions optimal for cellulolysis by an H2O2-Fe++ system, to account for the depolymerization observed in this study. Results suggest that these fungi may employ an H2O2-Fe++ mechanism to decompose wood cellulose or render it more susceptible to attack by conventional cellulases.

Cholinergic suppression of tardive dyskinesia.

Abstract: Tardive dyskinesia (TD), a hyperkinetic disorder associated with long-term neuroleptic treatment, may be a manifestation of imbalance of opposing DA and ACh dependent systems in the CNS (i.e., hyperdopamine activity or hypocholinergic function). Dopamine blocking agents give some transient relief of symptoms. Physostigmine, an anticholinesterase which enhances CNS acetylcholine action, has been given to 7 subjects with TD and measurements of their pathological movements made before, 45 min and 24 h later. All 7 subjects showed significant suppression of movement at 24 h. Many showed measurable decrement at 45 min. Side effects were minimal and transient. Physostigmine suppresses movements of TD.

Noise‐induced inner ear damage in newborn and adult guinea pigs

Abstract: Two-day (Group A), eight-day (Group B), and eight-month (Group C) old guinea pigs were exposed to 30 continuous hours of white noise at 119–120 db SPL One month later pathology of the organ of Corti was evaluated and quantitated by use of the surface preparation technique Percent cell damage was determined for outer hair, inner hair, outer pillar, and inner pillar cells at each of the four turns of the cochlea and for the cochlea as a whole Comparisons of pathology of each cell type were made between groups Mean percent outer hair cell damage per cochlea (± 1 SE) was 2372 ± 369 for Group A, 3698 ± 576 for Group B, and 724 ± 175 for Group C There was no significant difference in outer hair cell damage between Groups A and B Outer hair cells of Group A were significantly more damaged than those of Group C when damage in the cochlea as a whole was considered due to significantly greater damage in Group A at three and one half turns; likewise, outer hair cells of Group B were significantly more damaged than those of Group C when damage in the cochlea as a whole was considered due to significantly greater damage in Group B at two and one half and at three and one half turns A similar effect was observed in terms of pathology of inner hair cells and pillar cells: there was a trend toward increased damage in animals of Groups A and B compared with C Group C showed no outer or inner pillar cell damage, and only one of six animals had alterations in inner hair cells In contrast, outer and inner pillar cells were damaged in Groups A and B, and four of six animals of Group A and six of eight of Group B showed inner hair cell damage Recent electrophysiological and audiometric studies are discussed which, with the results of the present study, indicate greater susceptibility of young cochleas when compared with older cochleas, to noise-induced physiological and pathological alterations It would seem medically prudent to take special precautions to avoid exposing newborns to excessive noise

Crazing and fracture in crystalline, isotactic polypropylene and the effect of morphology, gaseous environments, and temperature

Abstract: Stress crazing is studied in three forms of crystalline, isotactic polypropylene (PP): (1) smectic/nonspherulitic, (2) monoclinic/nonspherulitic, and (3) monoclinic/spherulitic PP. Optical and scanning electron microscopy as well as stress—strain measurements are used to characterize crazing behavior in these three forms as a function of temperature (−210 to 60°C) and of the gaseous environment (vacuum, He, N2, Ar, O2, and CO2). Forms 1 and 2 are found to craze much like an amorphous, glassy polymer in the temperature range between −210 and −20°C, irrespective of environment. The plastic crazing strain is large close to the glass-transition range (ca. −20°C) of amorphous PP and in the neighborhood of the condensation temperature of the environmental gas. Near condensation, the gas acts as a crazing agent inasmuch as the stress necessary to promote crazing is lower in its presence than in vacuum. A gas is the more efficient as a crazing agent, the greater is its thermodynamic activity. Spherulitic PP (form 3) crazes in an entirely different manner from an amorphous, glassy polymer, showing that the presence of spherulites influences crazing behavior much more profoundly than the mere presence of a smectic or monoclinic crystal lattice. Below room temperature, crazes are generally restricted in length to a single spherulite, emanating from the center and going along radii perpendicular, within about 15°, to the direction of stress. They never go along spherulite boundaries. Gases near their condensation temperature act as crazing agents much as in nonspherulitic PP. Above room temperature the crazes are no longer related to the spherulite structure, being extremely long and perfectly perpendicular to the stress direction. Apparently the crystals are softened enough by thermally activated segmental motion to permit easy propagation of the craze. The morphology of the fracture surfaces and its dependence on temperature and environment is described and discussed. Concerning the action of gases as crazing agents it is argued that the gas is strongly absorbed at the craze tip, where stress concentration increases both the equilibrium gas solubility and the diffusion constant. Hence, a plasticized zone is formed having a decreased yield stress for plastic flow. This is considered to be the main mechanism by which the gas acts as a crazing agent. In addition, reduction of the surface energy of the polymer by the adsorbed gas eases the hole formation involved in crazing.

Tables of gehan's generalized Wilcoxon test with fixed point censoring

Abstract: Tables of Gehan's generalized Wilcoxon test statistic with single fixed point censoring are presented. It is shown that exact probability levels can be calculated in a very simple manner when the proportion of censored observations is large. The results of a simulation study investigating the adequacy of the large sample approximation for two different degrees of censoring are given.

The Size of Suspended Particle Matter in Air

Abstract: By means of the NASN cascade impactor the particle sizes of ambient aerosols can be measured by fractionating the particles according to their aerodynamic dimensions, and the fractions can be quantified gravimetrically. Data obtained with this instrument show that particulate matter suspended in urban air in the United States and Great Britain is remarkably uniform in distribution and that the particles are predominantly less than 1 microm in diameter. In Ankara, Turkey, the high proportion of particles larger than 1 microm in diameter are associated with the incomplete combustion of lignite; particulate concentrations in Ankara, however, are considerably higher than those measured elsewhere. The growth of particles in air during temperature inversions occurs in Cincinnati; the greater proportion of large particles found there during inversion periods can account for the reduction in visibility. Aerosols in the vicinity of highways are composed of particles larger than those found some distance away because of the reentrainment of debris by the traffic-induced turbulence. On the other hand, highway configuration and traffic volume have little effect on the size distribution of aerosols in samples collected away from the turbulence area of the roadway. Aerosols measured inside buildings are predominantly smaller in size and exhibit a narrower range of sizes than aerosols outside buildings.

Comparison of Three Methods of Estimating Surface Area and Biomass for a Forest of Young Eastern White Pine

Abstract: This paper presents estimates of foliage, branch and stem surface area, and ovendry weight, with estimates of precision of these statistics, for a 10-yr-old stand of eastern white pine on a 16-ha watershed at the Coweeta Hydrologic Laboratory in the Southern Appalachians. Three different methods were used to estimate the forest surface area and biomass: (1) stratified two-phase sampling, (2) two-phase sampling with a regression estimator, and (3) two-phase sampling with a ratio-of-means estimator. Stratified two-phase sampling was the most precise and appropriate method; the population was estimated to contain 5.3 ha foliage, 0.76 ha branches, and 0.13 ha stems per hectare of land surface. The estimated ovendry weight of tree components was estimated to be 2.71, 6.83, and 7.01 metric tons per hectare, respectively, for foliage, branches, and stems. The standard error of estimate for surface area and biomass ranged from 5 to 10 percent, depending upon the tree components of interest. Forest Sci. 20:97-700. Additional key words. Pinus strobus, sampling, conifer, foliage, branches, stems. THE QUANTITY OF TREE SURFACE AREA and tree biomass per unit area of land are inventory data needed to understand the flow of energy, nutrients, and water through forest ecosystems. Surface area, in contrast to biomass, has received little attention. Although Whittaker and WoodweU (1967) described the surface area relations for several deciduous forests in the eastern United States, comparable studies for evergreen forests are lacking. A deficiency common to surface area and biomass estimates in early studies of forest communities was the lack of statistical statements about the reliability of estimated quantities. The quality of results can vary greatly because a series of sampling steps are involved; thus, the error term for a population estimate depends on the error associated with each sampling step. Attiwill and Ovington (1968) and Satoo (1967) pointed out the need for appraising different methods of determining forest biomass. Ovington et al. (1967) and Attiwill (1966) calculated the magnitude of errors which may occur when different methods are used to estimate the biomass on a forest plot. However, forest ecosystem investigations may involve populations considerably larger than a plot, and procedures for assessing the precision of population prediction from sampled values become more complicated. Our study of surface area and biomass was stimulated by the results of several watershed experiments at the Coweeta Hydrologic Laboratory in western North Carolina. These experiments demonstrated that streamflow reductions of 10 percent occurred 10 yr after watershed cover types were changed from mature hardwoods to The authors are, respectively, Principal Plant Ecologist, Southeastern Forest Experiment Station, USDA Forest Service, Coweeta Hydrologic Laboratory, Franklin, N.C., and Mathematical Statistician, SEFES, Forestry Sciences Laboratory, Research Triangle Park, N.C. Manuscript received Sept. 1, 1972. volume 20, number 1, 1974 / 91 white pine (Swank and Miner 1968). The results suggested that appropriate vegetative parameters should be measured which logically describe cause and effect relationships when water losses are compared within and between forest ecosystems. Therefore, the immediate objectives of this study were twofold: (1) to estimate the quantity of surface area and biomass for foliage, branches, and stems in a 10-yr-old stand of eastern white pine (Pinus strobus L.) at one point in time by several methods, and (2) to derive error terms for these

Gas permeability of deformed polyethylene films

Abstract: Low-density polyethylene films strained up to 35% exhibit an initial increase of diffusivity and permeability which soon reach a maximum and subsequently drop to steadily decreasing values below those of the unstrained starting material. The sorption steadily increases and seems to approach a plateau. The maximum and the subsequent decrease are probably caused by significant, recoverable plastic deformation which seems to depress the tortuosity factor but not the free volume, as one concludes from the opposite trend of diffusion and sorption. Permanently deformed drawn or rolled films on the strain range from 0.5 through 3.0 exhibit a continuous decrease of diffusivity and permeability with an almost constant reduction of sorption. This postulates a decrease in free volume and a steadily decreasing tortuosity factor as a consequence of the gradually increasing fraction of the new, practically impermeable fibrous structure.

Estimation of the Distribution Function of a Continuous Type Random Variable through Randomized Response

Abstract: In 1965 Stanley Warner [8] illustrated a technique whereby one could estimate from a sample the proportion of persons in a population possessing some characteristic X, without pointedly asking the question, “Do you possess characteristic X?”. The present article uses a variation of these ideas suggested by Warner in a later paper [7] to estimate the distribution function of a continuous-type random variable. The technique is illustrated by estimating an income distribution from the responses of a sample of 500 individuals. The potential use of devices of this type in maintaining confidentiality of existing data files is apparent.

Metabolism of certain commonly used barbiturates.

Abstract: (1974). Metabolism of Certain Commonly Used Barbiturates. Drug Metabolism Reviews: Vol. 2, No. 1, pp. 265-278.

Influence of morphology on the transport properties of crystalline polymers

Abstract: The sorption and diffusion of penetrant of low molecular weight proceeds almost exclusively through the amorphous component of the semicrystalline polymer consisting of chain folds, tie molecules and free chain ends. Hence they depend on its transport properties and geometrical distribution which are both modified by mechanical and thermal treatment. The morphological changes induced by such treatment and the ensuing changes of transport properties cannot be described in a satisfactory manner by crystallinity and orientation. That is particularly true for drawn material with fibrous structure exhibiting a high anisotropy of diffusion and a drastic decrease of sorption and diffusion. Both effects are the consequence of the microfibrillar morphology with a large fraction of highly aligned taut tie molecules which by their closer packing eliminate many sorption sites, enormously reduce the diffusivity, and increase its concentration dependence and activation energy. The axial alternation of crystal blocks and amorphous layers making the microfibrils almost impermeable in the longitudinal direction produces the high anisotropy of diffusivity which may be reduced during plastic deformation of the fibrous structure by the increased number of interfibrillar tie molecules. Annealing relaxes the amorphous component by reducing the fraction of taut tie molecules, thus restoring the transport properties to values as observed in undrawn material. Another example of the overwhelming influence of morphology are the hard elastomers where the formation of a great many submicroscopical holes yields permeability increased by many orders of magnitude with no change in crystallinity and only modest increase of crystal orientation.

Plastic deformation and structure of extruded polymer solids

Abstract: During extrusion the main deformation and orientation of macromolecules is achieved by the flow component with longitudinal gradient. The orientation increases drastically if some solidification occurs during flow, yielding row-nucleated cylindrites and even fully oriented hard elastomers. In all cases the basic elements are stacks of very thin (∼100A) folded-chain lamellae connected by very few tie molecules. The plastic deformation of the solid transforms the original lamellar material into the extremely well oriented fibrous structure with high anisotropy of physical properties. The basic element are the highly aligned, very long and thin microfibrils bundled into fibrils. The axial strength of microfibrils is caused by the great many taut tie molecules connecting as almost crystalline bridges the crystalline blocks across the interposed amorphous layers. In plastic deformation of fibrous material the fibrils are sheared and longitudinally displaced. The latter mode is responsible for almost all the observed elongation. It smooths the structural defects on the surface of fibrils caused by the ends of microfibrils and thus produces a better lateral fit of fibrils resulting in rapidly increasing resistance to plastic deformation. The former mode extends the interfibrillar tie molecules and hence drastically increases their fraction per amorphous layer.

Agonist analogues of luteinizing hormone releasing hormone

Abstract: Novel peptide compounds of the formula Glu-His-X3 -X4 -X5 -X6 -X7 -X8 -Pro-W are provided together with their acid addition salts and their complexes with pharmaceutically acceptable metals. The compounds are LH-RH analogues and together with their salts and complexes exhibit LH-RH agonist activity. In the formula X3 and X5 are the same or different and each is phenylalanyl optionally substituted in the benzene ring; X4 and X6 are the same or different and each is selected from glycyl, alanyl (D- or L-) and asparaginyl; X7 is a radical of a neutral hydrophobic nonsulphur containing non-heterocyclic amino acid; X8 is a radical of a basic amino acid or is glycyl or phenylalanyl optionally substituted in the benzene ring; and W is selected from glycine amide and a group --NR1 R2. All references are to the L-amino acids and their radicals except in the case of glycine and unless otherwise stated. Also provided are methods for the preparation of the peptides, salts and complexes, pharmaceutical formulations containing them and methods for the preparation of such formulations, and methods for the use of the peptides, salts and complexes in human and in veterinary medicine.

Rapid annealing in irradiated CMOS transistors

Abstract: Data characterizing the transient annealing of the gate threshold voltage of contemporary CMOS transistors following exposure to pulsed ionizing radiation are presented and discussed. Devices tested during the study include those fabricated on both bulk silicon and silicon-on-sapphire substrates. Silicon dioxide and aluminum oxide gate dielectrics are evaluated. Leakage current phenomena associated with charge formation in dielectric substrates or dielectric isolation layers are also considered.

Substituted guanidine compounds as antifibrillatory agents

Abstract: Acid addition salts of N-p-methylbenzyl-N',N"-dimethylguanidine and of N-p-methoxybenzyl-N',N"-dimethylguanidine. The compounds have antiarrhythmic properties, and are useful specifically as antifibrillatory agents.