Showing papers by "Clemson University published in 1969"

Dynamic Model of the Anaerobic Digestion Process

Abstract: The major problem associated with the anaerobic digestion process has been its poor record with respect to process stability as evidenced by the reports of failing digesters. A dynamic model, which predicts failure, is presented for the process. The key features of the model are: (1) The use of an inhibition function to relate volatile acid concentration and specific growth rate for the methane bacteria; and (2) consideration of the un-ionized acid as the growth-limiting substrate and inhibiting agent. The use of an inhibition function is necessary to obtain a model that will predict failure. Consideration of the un-ionized acid as the inhibiting agent resolves the conflict between volatile acid inhibition and pH inhibition because the concentration of un-ionized acid is a function of both total volatile acid concentration and pH. Experimental evidence and evidence from the bacteriological literature are presented in support of the model. Simulation studies, using a digital-analog simulation program, of both batch and continuous flow systems provide additional evidence by predicting results commonly observed in the field during the start-up, or failure, or recovery of anaerobic digesters.

Microprobe techniques for determining diffusivities and respiration rates in microbial slime systems

Abstract: A microprobe electrode was used to determine dissolved oxygen concentrations near the surface and within a bacterial slime mass supplied with a continuous flow of nutrient solution. With dilute medium, the oxygen profile became level at high concentrations within the film, indicating substrate-limited respiration. More concentrated medium caused the profile to fall to low oxygen concentrations characteristic of oxygen-limited respiration. Oxygen responses to sudden changes in concentration of nutrient medium were measured. Estimates of microbial respiration rate and of diffusivity of oxygen were based on well-known diffusion equations.

A digital simulation of transient oxygen transport in capillary‐tissue systems (cerebral grey matter). Development of a numerical method for solution of transport equations describing coupled convection‐diffusion systems

Abstract: The mechanism by which oxygen is transported from capillaries into tissue for cell respiration has been a subject of interest since the work of August Krogh in 1919. Mathematical analyses of the diffusion process have been obtained by several investigators (11, 12, 18), but are limited in scope by the complicated nature of the problem. However, the solutions that exist give enough insight to inspire a more rigorous treatment. With the advant of electronic computers more complete analyses are now within reach (16). The human brain accounts for less than 4% of the total body weight, yet it uses 15 to 20% of the total body oxygen consumption. This high metabolic rate makes the brain particularly vulnerable to any change in the normal oxygen supply. The fact that following a cessation of cerebral blood flow, unconsciousness develops within 10 sec., and irreversible damage within 10 min., demonstrates the importance of understanding the dynamics of oxygen supply to the brain.

Accumulation of parathion and DDT by some algae and protozoa.

Abstract: SYNOPSIS Cultures of Anacystis nidulans, Scenedesmus obliquus, Euglena gracilis, Paramecium bursaria, and P multimicronucleatum were exposed separately to 2 pesticides They concentrated DDT 99 to 964 times and parathion 50 to 116 times when treated at 1 ppm (w/v), then held for 7 days At the sensitivities of the analyses, no metabolites of the pesticides were detected in any of the organisms

Some morphological types of bacteriophages in bovine rumen contents.

Abstract: Six morphological types of bacteriophage were found in bovine rumen contents. Minimal total phage count was 5 × 107 per ml of rumen fluid.

Biology of Melichares tarsalis in Association with Plodia interpunctella

Abstract: When reared on the eggs of Plodia viterpunctella (Hubner) (Lepidoptera: Phycitidae) under laboratory conditions of about 25°C and 75% relative humidity, the average durations of the stages of Melichares tarsalis (Berlese) (Acarina: Asceidae) in hours were: egg 52, larvae 23, protonymph 42, and deutonymph 47. The total period from egg deposition to adulthood averaged slightly more for females (166 hours) than for males (160 hours). The period from adulthood to oviposition was about 42 hours. Females laid an average of 3 eggs per day at 8-hour intervals. One female laid 62 viable eggs in 20 days. Mating lasted as long as 6 hours and females frequently mated more than once. The female:male ratio was slightly less than 3:1. Larvae of M. tarsalis did not feed, but all subsequent stages fed readily. Each feeding stage consumed about 1 egg per day. Females in all stages fed slightly more than males. The adult mites are phoretic on the adult moths.

Field Control of the Nantucket Pine Tip Moth by the Nematode DD-136

Abstract: Field investigations showed that the nematode DD-136 would kill Rhyacionia frustrana (Comstock) larvae under natural conditions. More first-generation tip moth larvae were killed than second or third. Nematode suspensions were aided in effectiveness by addition of 10% glycerin and to a lesser degree by addition of wetting agents or spreader-stickers, namely, 2% solution of Emgard 2050, Sole-onic CDS, and IGEPON AP-78. However, it was concluded that under the conditions of this study, DD-136 did not provide sufficient control of the Nantucket pine tip moth to recommend its use.

Effect of Elastic Stress on Some Electronic Properties of Indium

Abstract: We have measured the effect of elastic stress to 0.3 kbar on the resistance at room and helium temperatures and on the superconducting transition temperature of In whiskers. These whiskers have diameters 1 $\ensuremath{\mu}$ of about and axes parallel to a closest-packed or 101g direction. $\frac{\ensuremath{\partial}{T}_{c}}{\ensuremath{\partial}\ensuremath{\sigma}}$ is 51\ifmmode\pm\else\textpm\fi{}7 mK/kbar, in disagreement with results obtained by measuring the change in length of In crystals as they pass through the superconducting transition. At room temperature, $\frac{\ensuremath{\Delta}\ensuremath{\rho}}{\ensuremath{\rho}\ensuremath{\sigma}}=a+b\ensuremath{\sigma}$, where $a=(\ensuremath{-}0.4\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ ${\mathrm{bars}}^{\ensuremath{-}1}$ and $b=(14\ifmmode\pm\else\textpm\fi{}2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ ${\mathrm{bar}}^{\ensuremath{-}2}$.

Triple-Dipole Potentials in Classical Nonpolar Fluids

Abstract: Formulas which express the triple-dipole contribution to the pressure, internal energy, effective pair potential, and density expansion of the radial distribution function appropriate to classical nonpolar fluids are evaluated A rational approximation to tabulated theoretical values of the radial distribution function for argon based on the Lennard-Jones (12, 6) model is used to facilitate the numerical evaluation of the two- and three-fold integrals involved The nonadditive contribution to the pressure and internal energy of argon is several percent over the temperature-density range considered which includes the critical region It is found that the triple-dipole energy cannot account for the observed variation with density of the effective pair potential for argon reported by Mikolaj and Pings

Interstitial Migration in Aluminum

Abstract: Investigations have been made of how stage-I recovery depends on radiation doping and on the magnitude of the radiation dose for aluminum samples that were irradiated with 0.40-MeV electrons. Experimental results give (1) the amount of enhancement of stage I caused by prior low-temperature irradiations, and (2) the temperature shift and the fractional amount of the ${I}_{E}$ substage for different irradiation doses. By analyzing the ${I}_{E}$ recovery in terms of Waite's theory of random recovery, a value of 3.5 lattice constants is obtained for the capture radius for an interstitial-vacancy annihilation. The radiation-doping experiments are analyzed by considering a variable capture radius for the trapping of interstitials by impurities.

Laboratory mating behavior of the plum curculio.

Abstract: Studies were conducted to determine the mating behavior of Conotrachelus nenuphar (Herbst) in the laboratory. Combinations of aged and young adult curculios were found to mate as young as 6 days old; a single female mated at the age of 5 days. Males were capable of inseminating mature sperm at this early age, but the females did not oviposit fertile eggs until 8 days old. Males were shown to mate with as many as 16 different females by the time they were 30 days old. The average number of matings per male in a 30-day period was 10.4. Both virgin and non-virgin males were found to mate with more than 1 female in a 24-hr period. These females all produced large numbers of viable eggs. A single virgin male mated with 4 females in 1 day, and a single non-virgin male mated with 2 females in 1 day. The 1st as well as subsequent matings were responsible for large numbers of fertile eggs being produced. Females which had mated 1, 2, or 3 times were obtained by observing each mating. The average sperm content per female increased as the number of matings increased, although females that had mated only once produced what many workers have considered to be the average number of eggs per female. Females that mated 2 or 3 times produced more eggs during their lifespan than did those that mated only once.

Histological changes in the gonads and reproductive behavior of house flies following treatment with chemosterilants p,p-bis (1-aziridinyl), N-methylphosphinic amide and p,p-bis (1-aziridinyl)-N-(3-methoxypropyl) phosphinothioic amide.

Abstract: Evaluation of p, p -bis (l-aziridinyl)- N -methylphosphinic amide and p, p -bis (l-aziridinyl)- N -(3-methoxypropyl)-phosphinothioic amide for histological effects on gonadal tissue was made by feeding treated diet to adult Musca domestica L. A histological study of gonads showed that both compounds caused a drastic reduction in in spermatocyte cells in the testes of male flies, but aspermia never occurred. Some males treated with phosphinothioic amide showed recovery of spermatocyte cells 14 days after treatment. Primary oocytes in the ovary were least affected, although vacuolation of the yolk was evident in eggs of females treated with either compound. Atrophy of the ovaries began by the 10th day after treatment. The ovaries did not show recovery when the test was terminated 3 weeks after treatment. Females remained monogamous after mating with treated males thus indicating that these matings were satisfactory to the females. Males treated with either compound showed no difference from untreated males in initiation or duration of copulation.

Seasonal History of the European Corn Borer at Florence, South Carolina

Abstract: Seasonal history studies of Ostrinia nubilalis (Hubner) at Florence, S. C. in 1967–68 revealed 4 generations per year. Adult emergence began in April of both years. Oviposition of 1st-, 2nd-, and 3rd-generation egg masses was heaviest on March-, April-, and May-planted corn respectively, with 4th-generation egg masses being observed primarily on Panicum sp. The percentages of larvae diapausing in field cages were 0.9, 54.3, and 100.0 for generations 1–3 in 1967 and 1.1, 18.9, 90.5, and 100.0 for generations 1–4 in 1968.