Thesis (M.S.)--Virginia Polytechnic Institute, 1962. / Vita. Abstract. Includes bibliographical references (leaves 121-124). Also available via the Internet.

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O objetivo deste trabalho foi estudar a capacidade de adsorção de ferro pela levedura Saccharomyces cerevisiae visando à incorporação em ração animal, utilizando, para isso, o sulfato ferroso. Foram realizados ensaios para determinar a tolerância de uma linhagem de Saccharomyces cerevisiae em concentração de ferro, onde se escolheu uma concentração para estudo de 5,36 mmoles de Fe +2 /L em função de inibição de crescimento e tempo para obtenção de massa satisfatória. Em seguida, foram realizadas cinco fermentações consecutivas para enriquecimento da levedura com Fe +2 , utilizando-se como inoculo todo o fermento recuperado da fermentação anterior descontada a alíquota tomada para a análise do teor de Fe +2 . Uma fermentação com células inativadas termicamente também foi realizada para determinar a capacidade de adsorção de Fe +2 pelas mesmas. Foi observado acúmulo crescente de Fe +2 na levedura a cada fermentação, iniciando-se por 1,43 mmoles de Fe +2 / kg de matéria seca para 6,68 mmoles de Fe +2 / kg de matéria seca após cinco fermentações consecutivas. / The aim of this work was to evaluate the iron adsorption capacity of the Saccharomyces cerevisiae yeast, for animal food supplementation purpose. The iron tolerance of one Saccharomyces cerevisiae strain was evaluated, choosing 5.36 mmoles Fe +2 as the concentration for the further assays. Five concecutive fermentation were done for the iron enrichment of the yeast, using as innoculum the whole biomass formed in the previous fermentation except for the amount employed for iron determination. A batch essay with inactive cells was also conducted for the determination of Fe +2 adsorption. Results showed an increasing accumulation of Fe +2 in all fermentation, from 1.43 mmoles kg -1 of dry mass at the beginning, to 6.68 mmoles kg -1 of dry mass, after five consecutive fermentations.

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Browse biomass production of Salix spp. and Betula glandulosa on a wetland in central British Columbia is estimated. Based on an extensive review of much of the literature pertaining to shrub biomass and shrub density estimation, a technique combining regression estimates of average stem biomass with a density estimate obtained using the corrected point distance method was applied. It was found that the best regression relationships were obtained using natural logarithmic transformations of the dimension and biomass variables. It was possible to obtain acceptable biomass equations for the four Salix species encountered without differentiating between the species. More accurate predictions of biomass were achieved using site specific equations and equations based on pooled site data than with general equations. It was concluded that the value of the approach taken is limited if site specific equations are required because of the considerable time required for sample collection and preparation. / Forestry, Faculty of / Graduate

O objetivo deste trabalho foi estudar a capacidade de adsorção de ferro pela levedura Saccharomyces cerevisiae visando à incorporação em ração animal, utilizando, para isso, o sulfato ferroso. Foram realizados ensaios para determinar a tolerância de uma linhagem de Saccharomyces cerevisiae em concentração de ferro, onde se escolheu uma concentração para estudo de 5,36 mmoles de Fe +2 /L em função de inibição de crescimento e tempo para obtenção de massa satisfatória. Em seguida, foram realizadas cinco fermentações consecutivas para enriquecimento da levedura com Fe +2 , utilizando-se como inoculo todo o fermento recuperado da fermentação anterior descontada a alíquota tomada para a análise do teor de Fe +2 . Uma fermentação com células inativadas termicamente também foi realizada para determinar a capacidade de adsorção de Fe +2 pelas mesmas. Foi observado acúmulo crescente de Fe +2 na levedura a cada fermentação, iniciando-se por 1,43 mmoles de Fe +2 / kg de matéria seca para 6,68 mmoles de Fe +2 / kg de matéria seca após cinco fermentações consecutivas. / The aim of this work was to evaluate the iron adsorption capacity of the Saccharomyces cerevisiae yeast, for animal food supplementation purpose. The iron tolerance of one Saccharomyces cerevisiae strain was evaluated, choosing 5.36 mmoles Fe +2 as the concentration for the further assays. Five concecutive fermentation were done for the iron enrichment of the yeast, using as innoculum the whole biomass formed in the previous fermentation except for the amount employed for iron determination. A batch essay with inactive cells was also conducted for the determination of Fe +2 adsorption. Results showed an increasing accumulation of Fe +2 in all fermentation, from 1.43 mmoles kg -1 of dry mass at the beginning, to 6.68 mmoles kg -1 of dry mass, after five consecutive fermentations.

This study is one phase of a ten-year project designed to evaluate forest-wildlife relationships. The project was initiated in 1958 on the Jefferson National Forest, Broad Run Wildlife Management Area, Craig County, Virginia. The objective of the study was to determine if correlations existed between quantities of available deer browse in the understory of a particular forest cover type and several site quality measurements. The purpose of the study was to determine if weights of browse per acre could be estimated reliably by utilizing easily obtained site quality measurements instead of clipping and weighing browse. Eight site quality measurements (variables) were tested. These were: site index, depth of the A₁ soil horizon, position on slope, basal area per acre, aspect (exposure), percent of slope, elevation, and the number of clipped stems per sampling unit. Fieldwork was conducted in two major forest cover types; the oak, hickory, poplar, white pine type (cove hardwoods type), and the mixed oak-pine type. Sampling units were located randomly, in pairs, within each of these two forest cover types. Each sampling unit consisted of a circular 1/4 acre plot and a square 1/100 acre plot located at the center of the circular plot. A system of double sampling was used to obtain browse weight data and site quality data for comparisons. Data on eight variables recorded at each 1/4 acre sampling unit were compared with the quantity of browse clipped from the 1/100 acre sampling unit located at the center of that particular 1/4 acre plot. A multiple regression analysis was used to determine the degree of correlation between quantities of browse (available browse) clipped from sampling units and all measurements of the eight independent variables (site quality measurements) recorded on sampling units. The final analysis of the oak, hickory, poplar, white pine cover type data indicated that the variables significantly related to browsing weights per acre were the number of stems clipped per sampling unit and the depth of the A₁ soil horizon. These two significant variables explained 48,63 percent of the total variation in browse weights occurring between sampling units. Using only the two significant site quality measurements (independent variables), the final estimating equation was: Y (pounds of browse per acre) = -0.14 + 0.06 (number of stems clipped per sampling unit) + 0.61 (depth of the A₁ horizon, inches). The final estimating equation should not be used for reliable estimates of browse production in the oak, hickory, poplar, white pine forest cover type. A total of 51.37 percent of the variation in browse weights occurring between sampling units is unaccounted for in this equation. The final analysis of the mixed oak-pine cover type data indicated that the only variable significantly related to browsing weights per acre was the number of stems clipped per sampling unit. However, this significant variable explained only 17.97 percent of the total variation in browse weights occurring between sampling units. Using only the one significant site quality measurement (independent variable), the final estimating equation was: Y (pounds of browse per acre) = 2.24 + 0.07 (number of stems clipped per sampling unit). The final estimating equation should not be used for reliable estimates of available browse production in the mixed oak-pine forest cover type. A total of 82.03 percent of the variation in browse weights occurring between sampling units was unexplained in this equation. More research is necessary to determine other easily measured environmental factors (variables) which might bear a significant relationship to quantities of available deer browse produced in the two forest cover types sampled. When several more of these significant variables are discovered, the addition of these variables to the estimating equations for the two cover types might account for a large enough percent of the explained variation to enable the game biologist to use the equations for reliable estimates of browse production. / Master of Science

The purposes of this investigation which was conducted from September 1954 through October 1955, were (1) to determine the differences in available nutrients in selected deer browse species growing on different soils, (2) to investigate the variations in available soil nutrients as they may relate to chemical composition of selected deer browse species, and (3) to determine the variations in available nutrients in the selected browse species during different seasons of the year. The current year’s growth of twigs from flowering dogwood (Cornus florida), black locust (Robina pseudoacacia), and red maple (Acer rubrum) were collected at two-month intervals on study areas whose soils had arisen from either Brallier, Clinton, Huntersville chert, or Martinsburg shale geological formations. A proximate analysis was run on each browse collection. In addition to the above three species, rhododendron (Rhododendron maximum) and buffalo nut (Pyrularia pubera) were collected from the Brallier study area and analyzed. One-third of the samples of dogwood, locust, and maple that were collected after leaf fall in October 1955, were analyzed for calcium, phosphorus, cobalt, and manganese. Soil samples were collected on each area and analyzed by a flame spectrophotometer, LeMotte Soil Testing Outfit, and a rapid method. The soil which arose from the Brallier study area was lowest in value for phosphorous and second highest in values for total exchangeable cations and organic matter. The Clinton study area values were second highest in pH, phosphorous, and base saturation, and was highest in organic matter and manganese content. The chert values were the next lowest for phosphorus and lowest for pH, calcium, total exchangeable cations, and base saturation. The shale study area soil gave the highest values for pH, calcium, phosphorous, base saturation, and total exchangeable cations although it was lowest in organic matter. Of the three browse species collected from all the study areas, dogwood was generally high in moisture content, ether extract, ash, and nitrogen-free extract while being average in protein and low in crude fiber. Locust was high in protein and crude fiber and low in moisture, ether extract, and nitrogen-free extract. Maple was generally high in ether extract, crude fiber, and nitrogen-free extract and low in protein and ash. Rhododendron and buffalo nut were collected from the Brallier study area only. In comparison with the other three species on that area, rhododendron was very high in moisture and nitrogen-free extract; average to low in protein, ether extract, and crude fiber; average to high in ash. Buffalo nut was very high in moisture, protein, and ash; average in ether extract and crude fiber; and low in nitrogen-free extract. Seasonal trends in nutrient values for three browse species collected in all areas were observed. Protein content rose generally during the dormant months. Moisture content decreased from June through December and was followed by a rise that lasted until June. There was a rise in ether extract from September through June whereas the level of ash content was erratic during this period. Crude fiber was fairly stable in red maple and black locust although erratic in dogwood. There was a decrease in the nitrogen-free extract during the winter. Trends and consistencies in the nutritive values of the three species collected on all study areas, based on the study area on which they occur, are generally in the order of being high or low for one or two individual species rather than for all the species, or else they are considerably erratic. The different species have different nutritive values when growing on the same soil. During April and August, the different soils have their greatest effect on the nutritive values of plants; moisture content is greatly affected by the soil, and protein content is only slightly less affected. Except for the months of February and August, at least three of the six nutritive qualities of the plants were affected by the interaction between the plant and the soil. Analyses for minor elements reveal that black locust had the highest phosphorous and cobalt content; dogwood had the highest calcium content; red maple had the highest manganese content. On three of the four study areas, the manganese content of red maple exceeded the toxic level for bovines. On the chert area, dogwood and red maple were deficient, by bovine standards, in cobalt. / Ph. D.

no abstract provided by author / Master of Science