Doctoral Dissertations

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An investigation of the effects of cold working upon copper
Davis, G. Maslin (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1929)
For many years, an equation to express the relationship of stress to strain has been desired, and recently a study of the change of properties resulting from the cold working of a metal has assumed important proportions. For stresses below the elastic limit, Hooke's law and Poisson's ratio are applicable, but above the elastic limit relation to stress to strain follows a different law. Copper and steel are both ductile materials, and it is, therefore, logical to assume that they will show similarity of characteristics. Copper and steel have individual peculiarities, but copper appears to be erratic in its behavior. For example, the modulus of elasticity of steel varies, according to some law resembling a hyperbolic function of the cold working. However, copper does not follow a similar law. The investigation of cold worked copper is of importance in practice. In the manufacture of copper wire, for instance, it is desirable to know how the elastic limit, the maximum load, and the plastic working limit vary as the degree of cold drawing increases.
An investigation of methods for the determination of the colloidal particle size of viscose
Sweet, Warren William (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1932)
The purpose of this problem is to investigate the various methods which could possibly be used to accurately determine the particle size of the viscose sol, with the view of using the best method to follow the colloidal changes in ripening viscose.
A study of the crease-resistance of viscose rayon
Sugarman, Nathan (Virginia Tech, 1942-05-01)
Crease-resistance is a very greatly desirable property in textile fibers. Of the natural fibers, wool exhibits this property to the greatest degree, followed by silk, cotton, and flax, which has a very low crease-resistance. The artificial cellulose fibers fall considerably below wool and silk in this respect. The improvement of the crease-resistance of rayon and other fibers has been sought in various after-treatment processes, in which substances are either deposited within the fiber, or react with it. There are numerous patents (22) for such methods of imparting crease-resistance. It would be highly desirable if the crease-resisting powers could be achieved "by a modification of the intrinsic properties of a fiber, that is, by producing a fiber which already is crease-resistant. The purpose of the work reported here was to attempt to produce a viscose rayon fiber with better crease-resisting properties, and to study the effect of a variation in the cellulose chain length distribution in the rayon upon this property. This work was done under a Fellowship of the Behr-Manning Corporation, Troy, New York.
Reactions of cellulose in liquid sulfur dioxide
Brooks, Lawrence Cornelius (Virginia Tech, 1942-06-29)
It appears impossible to nitrate cellulose in a medium of liquid sulfur dioxide either ~~th ruming nitric acid, a mixture of fuming nitric acid and sulfuric acid t a mixture of fuming nitric acid and phosphorus pentoxide, a mixture of fuming nitric acid, phosphorus pentox1de ana chlorine gas, or with nitrogen tetroxide. This is attributed to the fact that in each case the primary reaction ist hat of the formation of the compound N23209.
The feasibility of commercial utilization of cotton fabric and cotton conversion products for synthetic lumber
Zur Burg, Frederick William (Virginia Tech, 1942-12-01)
During the past two decades much scientific investigation has been directed toward the elimination and profitable utilization of the waste products of manufacture and agriculture. One of the outstanding developments has been an industry that utilizes agricultural waste products to produce synthetic lumber. Such materials as cornstalks (1), bagasse (2), wheat straw (3), wood (4), whole cotton plants (5) and etc., have entered into the manufacture of the different synthetic lumbers, and the different products have met with varied degrees of success. An investigation was undertaken to determine the feasibility of utilizing cotton stalk as a basic material in the manufacture of synthetic lumber. The cotton stalk is not just an ordinary waste, but a highly undesirable refuse when left standing in the fields; for, during the winter months the dead plant acts as a home for the boll weevil then in its dormant stage.
The dissolution of urinary calculi
Claffey, Lawrence Webster (Virginia Agricultural and Mechanical College and Polytechnic Institute, 1943)
A brief investigation was made of various organic and inorganic solvents for the dissolution of urinary calculi in vitro and Albright’s (1) citric acid buffer and a solvent designated in this investigation simply as “G” (33) were shown to be the most efficient solvents. Further investigation showed that something was necessary to increase the efficiency of these solvents, as the dissolution would proceed to a certain point where the solvent ceased to act. It was at this point that the investigation changed its course and the attack was centered on the organic colloidal matrix in the structure of the stone. It is a well known fact that this organic matrix is resistant to weak acids and bases (30) and therefore the course of the investigation pointed to those most remarkable agents, “the enzymes”, which due to their enormous amount of surface energy are capable of producing astonishing results. The enzymes investigated were not selected for their specific action, but they were selected for the purpose of studying the effect of their surface energy on the colloidal matrix of urinary calculi. The investigation indicates that a calculus pretreated with urease for fifteen minutes, followed by a 6 hour irrigation with “G” (33) solution is sufficient to cause dissolution and disintegration in nearly all of the one hundred calculi selected at random. (See Table 5) The ability of urease to hasten disintegration may be due to its activity on the colloidal matrix, causing it to swell, thereby giving back the former hydrotropic properties mentioned by Snapper (52). Colloidal material was isolated from a large calculus and was subjected to the action of urease. After 6 hours the colloids from the calculus had swollen approximately five hundred times their original volume, and changed from a dark brown-colored material to a white translucent gel. These organic colloidal matrices of urinary calculi are apparently of a reversible nature and irreversible as investigators have assumed in the past (30). Investigations were made and reported in various sections of this paper on the ability of other enzymes, peroxide, and acids to act as dissolution agents or as aids to dissolution. An efficient in vitro irrigator Fig. 1 is described and its merit in the irrigation of urinary calculi lies in the facts that its construction is simple, its rate of flow can be accurately regulated by a slight manipulation, and the calculus can be treated in various ways without removing it from the original crucible. It now remains for the urologist to investigate the possibility of in vitro dissolution, using the above auxiliary agent. It is suggested that the urease might be used simultaneously with the irrigation solvent.
The physiology of the genus bacillus
Bozeman, Samuel Richmond (Virginia Polytechnic Institute, 1945)
The object of the present investigation was to determine quantitatively the extent of glucose and d- and l-arabinose utilization in order to separate it from the other two factors influencing the pH change in the medium. The pH of the carbohydrate media employed was determined potentiometrically, using a glass electrode in order that the pH produced could be compared with the extent of utilization of these carbohydrates. Likewise, the pH produced by the same Bacilli in peptone alone was determined so that it could be compared with the pH produced in the carbohydrate-peptone media. The fundamental observations concerned with the metabolism of the genus Bacillus (which may be derived from this study) may be of value in the taxonomic identification of various members of this group of organisms, and might lead to other interesting conclusions regarding the metabolism of these organisms in pure laboratory culture and also in mixed cultures in the natural habitat.
The solvent extraction of oil from acorns
McCormack, Ralph Henry (Virginia Polytechnic Institute, 1945)
The development and evaluation of a commercial process for the production of benzene hexachloride
Gradishar, Frederick John (Virginia Polytechnic Institute, 1948)
The oxidation of ethylene to ethylene oxide
Jacknin, Bernard (Virginia Polytechnic Institute, 1949)
The purpose of this investigation was to determine the effect of the operating variables of type of reactor, catalyst, ethylene feed concentration, temperature, and contact time on the products of oxidation of ethylene to ethylene oxide; and together with subsequent hydrolysis to evaluate the commercial feasibility of the manufacture of ethylene glycol. The review of the literature contained 10 references. The equipment employed was arranged as indicated in a general flow diagram for the system. A silver catalyst activated by barium peroxide was employed and prepared on No.7 and No.3 Valencia pumice as the carrier according to Wiseman. For the analysis of ethylene oxide the procedure employed was a modification of that suggested by Vaughan and Wiseman. The carbon dioxide content of the product gases was determined by absorption of the carbon dioxide by ascarite; moisture was removed by means of drierite. Data and Results: A summation was made of operating conditions, yields and conversion in the air oxidation of ethylene in a fixed bed and fluidized bed reactor as a function of type of catalyst, contact time, reactor bath temperature, ethylene feed concentration, employing a barium peroxide activated silver catalyst coated on No.3 and No.7 Valencia pumice , uncoated pumice, and mixtures of these catalysts. It was found advisable to employ a 50% mixture of catalyst-coated and uncoated carrier in the tests because of the tendency toward fusion of the catalyst particles when used alone as the reactor charge . An increase the ethylene feed concentration from 3 to 9 per cent does not seem to appreciably affect either the conversion or yield.
The correlation of mechanical properties of ethyl cellulose films with shape of distribution curves
McNeer, Rembert Durbin (Virginia Polytechnic Institute, 1949)
A correlation of the mechanical properties of cellulose nitrate films as a function of the shape of the distribution curve
Rouse, Benjamin Preston (Virginia Polytechnic Institute, 1949)
The experimental evaluation of definite integrals
Tyler, George William (Virginia Polytechnic Institute, 1949)
When making an estimate of the total of some quantity, sampling at carefully selected points will frequently be preferable to employing a method which involves randomization. The estimation of the total stand of timber on a given area or the amount of energy being released in a given time and space are examples of problems where specified points for sampling should result in a reduction the error of estimate. Problems such as these naturally lead us to to numerical integration methods. In the case of single integrals, the Newton-Cotes formulae can be applied directly to experimentally determined ordinates at equally-spaced abscissa points and are of great practical importance. Gauss’ formulae yield maximum efficiency with respect to controlling the polynomial error and can be used appropriately when an analytical expression for the curve in question is available but defies exact integration, or if for some other reason the statistical error is of minor importance. Tchebichef’s a formulae give maximum efficiency with respect to controlling the statistical or observational error. The basic elements in the development of numerical integration formulae like Newton-Cotes, Gauss' and Tchebichef's, can be extended to developing formulae for the approximate evaluation of multiple integrals. In the case of double integrals, an eight point and a thirteen point formula for fifth degree accuracy and a twelve point and a twenty-one point formula for seventh degree accuracy have been developed for integrating over a rectangle and similar formulae have been developed for integrating over areas bounded by a parabola and a straight line or two parabolas. Formulae for the numerical evaluation of triple integrals taken over a rectangular parallelepiped are developed, including a twenty-one point formula with fifth degree accuracy. It is shown that comparable formulae can be developed for integrating functions of more than three variables and a 2n /- 1 point formula with third degree accuracy for integrating a function of n variables over a rectangular n-space is obtained. In many problems involving statistical estimation, the dominant source of inaccuracies will be the error of observation. The magnitude of this error can be estimated by subjecting the observations to an orthogonal transformation which will isolate the trends and leave the residual variance free from these effects. This treatment is most easily carried out in terms of orthogonal polynomials and it is shown that this type analysis can be extended to functions of several variables.
The design, construction, and operation of a centrifugal molecular still
Coli, Guido John Jr. (Virginia Tech, 1949-05-15)
The three basic requirements for unobstructed, short path distillation are: a surface over which a think layer of distilland is distributed, a cooler condensing surface in close proximity to the evaporating surface, and a suitable system for evacuating the space between the two surfaces. When the distance of transfer between the evaporating and condensing surfaces is comparable to the mean free path of the vapor molecules in the residual gas, the process is known as molecular distillation. [Continued in document]
Ultrasonic coagulation of phosphate tailing
Thompson, Dudley (Virginia Polytechnic Institute, 1950)
no abstracts provided by author
Lactic acid fermentation of xylose by Escherichia coli: carbon tracer studies on the C₂ + C₁ condensation reaction
Nutting, Leighton Adams (Virginia Polytechnic Institute, 1950)
The ubiquitous distribution of the pentose molecule in nature and particularly its presence in certain enzymes and in nucleic acids emphasizes the metabolic significance of these carbohydrates. In living systems the pentoses are undergoing continuous metabolic changes. It thus appeared that investigations concerning the metabolic decomposition of the pentose molecule would be important from a comparative biochemical point of view. The advantages of a microbial system as a working model for biochemical investigations are well known. Investigations concerning pentose metabolism were, therefore, carried out with a washed bacterial cell suspension utilizing xylose as a sole substrate. Previous investigators have obtained evidence that one of the first reactions in the fermentation of pentoses was a carbon bond cleavage resulting in the production of a C₃ and a C₂ fragment. The importance of the C₂ fragment in enzymatic systems is well recognized and it thus seemed plausible that investigations on bacterial pentose fermentations would be of significant value to the field of intermediary metabolism. Preliminary investigations revealed that cells of Escherichia coli K-12 grown in the presence of pentose possessed the ability to ferment pentoses in the nonproliferating cell state. Additional experiments concerning the anaerobic decomposition of xylose re-emphasized the metabolic importance of the C₂ fragment. In fermentations conducted at low pH, lactic acid was produced in a ratio of approximately 1.3 moles per mole of xylose fermented. Since a maximum of only 1.0 moles of lactic acid could have been derived from the C₃ portion of the xylose molecule this was taken as a priori evidence that the C₂ portion of the C₅ molecule was also involved in the formation of lactic acid. Furthermore, at low pH, there was a net fixation of C0₂ which indicated that a direct participation of C0₂ was involved in the production of lactate. There were a number of pathways by which lactate could have been formed from C₂ and carbon tracer experiments were conducted in order to determine the main mechanism of C₂⟶C₃ in this system. These experiments demonstrated that C₂ tracers (C¹⁴H₃C00H and C¹⁴H₃CH₂0H) were converted to the CH₃-CH0H-portion of lactate while C₁ tracers (c¹³0₂ and HC¹⁴OOH) appeared in the lactate carboxyl. This latter piece of evidence was a further indication that lactate was formed via a C₂ + C₁ condensation. This condensation functioned at pH 7.4 as well as at pH 5.3. With C¹⁴H₃C00H as tracer succinate was labeled exclusively in the methylene carbons and it was concluded that the lactate was not in close equilibrium with succinate. The production of lactate via C₂ + C₁ condensation further emphasizes the general role of this reaction in intermediary metabolism. The fact that C₂ produced from pentoses apparently can be converted to C₃ also provides a mechanism for the conversion of pentoses into hexoses and vice versa.
A study of the mechanism of aromatic cyclodehydration
Van Oot, James G. (Virginia Polytechnic Institute, 1950)
The oxygen uptake by pseudomonas fluorescens on glucose, xylose, arabinose and acetate under varying conditions of substrate concentration and environmental temperature
Watkins, Peter Haynes (Virginia Polytechnic Institute, 1951)
Industrial waste pollution is a problem of considerable magnitude and of great importance to modern industry. One critical aspect of waste pollution is reduction of dissolved oxygen in natural waters resulting from the oxygen uptake of bacteria while digesting organic wastes. Fundamental information concerning the effect of various physical and chemical factors on the rate of oxygen uptake by bacteria was sought by investigating the rate of oxygen uptake by Pseudomonas fluorescens, a common water organism, as a function of the concentration of substrate and the temperature of environment. The substrates were D-glucose, D-xylose, L-arabinose and acetate, and the temperatures investigated ranged from 15 to 37 ºC. Oxygen uptakes were determined manometrically using the direct Warburg method in conjunction with resting cell techniques. In all tests 3.0 milligrams or Pseudomonas fluorescens (stated as dry bacterial protoplasm) were suspended in 2.5 milliliters of 0.05 molar phosphate buffer of pH 6.8. At 25 °C, for all substrates with the exception of acetate, the rate of oxygen uptake is dependent on concentration in the lower concentration ranges, and follows the Michaelis-Menten equation. Saturation concentrations stated as millimoles per test were 0.0500 for glucose and 0.600 for xylose. Saturation had not been reached in the case or arabinose at the highest concentration tested of 0.8000 millimoles per test. The rate or oxygen uptake increased with acetate concentration up to 0.1000 millimoles per test, and at concentrations above this value a decrease in rate of uptake was observed. A special equation was developed to cover the latter case. When substrate concentrations were held constant and temperature of the environment was varied from 15.0 to 37.0 °C the rate of oxygen uptake increased with temperature in all cases. For glucose the rate of change of the rate of oxygen uptake was 15.8 ± 1.6 microliters per hour per degree centigrade between 15.0 and 20.0 °C, 2.4 ± 0.2 microliters per hour per degree centrigrade between 20.0 and 25.0 °C, and 11.7 ± 1.2 microliters per hour per degree centigrade between 25.0 and 37.0 °C. When glucose concentration was held constant at 0.1000 millimole. For xylose the rate of change of the rate of oxygen uptake was 18.0 ± 1.8 microliters per hour per degree centigrade between 15.0 and 18.0 ºC, 3.9 ± 0.4 microliters per hour per degree centigrade between 18.0 and 35.0 °C, and 16.5 ± 1.6 microliters per hour per degree centigrade between 35.0 and 37.0 ºC when xylose concentration was held constant at 0.400 millimole. For arabinose the rate of change of the rate of oxygen uptake was 10.4 ± 1.0 microliters per hour per degree centigrade between 15.0 and 17.5 °C, 0.4 ± 0.0 microliters per hour per degree centigrade between 17.5 and 30.0 ºC, and 2.4 ± 0.2 microliters per hour per degree centigrade between 30.0 and 37.0 ºC when arabinose concentration was held constant at 0.400 millimole. For acetate the rate of change of the rate of oxygen uptake was 19.7 ± 2.0 microliters per hour per degree centigrade between 15.0 and 18.0 ºC, 2.8 ± 0.3 microliters per hour per degree centigrade between 18.0 and 28.0 °C, and 12.5 ± 1.5 microliters per hour per degree centigrade between 28.0 and 37.0 °C when the acetate concentration was held constant at 0.0500 millimole.
Respiration rates on various nitrogenous substrates by Zoogloea ramigera: a bacterium found in aerobic phases of sewage treatment
Rich, Linvil Gene (Virginia Polytechnic Institute, 1951)
The effect of ultrasonic irradiation on the specific reaction rate constant in the acid hydrolysis of ethyl acetate
Gray, Walter C. (Virginia Polytechnic Institute, 1952)
The speed of a chemical reaction is important in determining the efficiency of many industrial chemical reactions. In organic reactions particularly, when there is the possibility of several reactions going on simultaneously, that reaction which is fastest is the one that predominates and often affects the economics of the process. The object of this investigation was to determine the effect of ultrasonic irradiation on the specific reaction rate of the hydrolysis of an aqueous solution of ethyl acetate in the presence of hydrochloric acid as the catalyst. The commercially obtained ultrasonic generator was limited to four frequencies - namely, 400, 700, 1000, and 1500 kilocycles. Two thousand volts plate voltage could be applied to the quartz crystal plates provided the plate current did not exceed 360 milliamperes. A special pyrex glass reactor was designed and constructed in order that isothermal conditions could be maintained within the boundary of the reactor. The period of time the reaction mixture was subjected to ultrasonic irradiation was arbitrarily set at 10 minutes for a given power and frequency at 19 ± 0.1°C and 30 ± 0.1°C respectively. The tests were then repeated using a 20 minute period of irradiation. Individual mixtures were respectively irradiated at 0, 500, 1000, and 1500 volts plate voltage. The composition and volume of the mixture irradiated was 100 ml of 1.9904 N hydrochloric acid, 90 ml of distilled water free from carbon dioxide, and 10 ml of ethyl acetate making a total volume of 200 ml. The chemical reaction assumed for the investigation was CH₃COOC₂H₅ + H₂O + H⁺ ⇋ CH₃COOH + C₂H₅OH + H⁺ The course of the reaction was followed in such a way that the concentrations of the reacting substances were not disturbed. Samples of the mixture were drawn off at intervals and titrated with sodium hydroxide using phenolphthalein as the indicator. Calculations were based on the difference of the titration at any time t in minutes and the titration at the end of 24 hours. When the reaction was completed, this difference was a measure of the concentration of ethyl acetate remaining unchanged or unhydrolyzed at time t. Each molecule of ethyl acetate that hydrolyzed produced one molecule of acetic acid, and the increase in acidity was a direct measure of the amount of ethyl acetate that had reacted. The amount of hydrochloric acid remained unchanged throughout the experiment. The concentrations of ethyl acetate calculated from the differences between the titration values and the final titration were arranged in tabular form. A graph was drawn on semilogarithmic paper by plotting the concentration of ethyl acetate, c, against time, t, in minutes and the best straight line through the points. Using the equation, - log c_A (k / 2,303) t+ constant, the specific reaction rate, k, was calculated by multiplying the slope of the line by 2.303. The activation energy, E, was calculated from the values of k at 19 ± 0.1°C and 30 ± 0.1°C using the equation, E = [2.303 log₁₀ k₂/k x R x T₁ x T₂] / [T₂ - T₁] where k₁ = specific reaction rate at 19 ± 0.1°C k₂ = specific reaction rate at 30 ± 0.1°C R = Constant T₁ = Absolute temperature for 19 ± 0.1°C T₂ = Absolute temperature for 30 ± 0.1°C The results of this investigation showed that the specific reaction rates were increased by ultrasonic irradiation of 400, 700, 1000, 1500 kc in the order of five percent for 20 minutes irradiation over the rates for 10 minutes irradiation.

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