Weed control in transplanted tomatoes with diphenamid, trifluralin, and paraquat was evaluated under field conditions on a predominantly Grosclose silt loan soil on the Virginia Polytechnic Institute Horticulture farm near Blacksburg, Virginia. The herbicides were used singularly and in certain combination at various rates and times of application. Diphenamid applied on previously cultivated soil at two weeks after transplanting tomato plants gave superior weed control with no apparent injury to tomato plants. However, the eame herbicide gave poor post emergence weed control and yield of tomatoes when applied after small weeds were present. Growth of tomato plants·was. suppressed by competition from weeds; however, ripening of tomatoes was accelerated as compared to untreated cultivated plants. Trifluralin applied pre planting also gave good weed control, but when applied post transplanting weed control was poor po•eibly due to incorporation technique. The higher rate of this herbicide seaweed a decrease in growth and yield of the crop. A mixture of diphenamid plus paraquat was effective on small weeds, but this treatment has less possibilities in commercial production as the spray cannot be directed to avoid contact injury to tomato plants. / Master of Science

In this work, four investigations of stratified flow were conducted in closed conduits, which included, l. numerical solution of velocity distribution by using a digital computer, 2. analytical solution and experimental verification of the internal surge wave velocity, 3. experimental observation on the mutual intrusion phenomena, and 4. experimental investigation of the internal hydraulic jump. An apparatus consisting mainly of a total length of 13 feet of transparent plexiglas pipe, two liquid pumps, a separator, two constant head tanks, a receiving tank, flow control valves, manometers, and discharge measuring devices, was built for the above investigations. The equation of motion was derived for the velocity distribution, starting from the Navier-Stokes equations. A special Poisson equation with a constant term on the right hand side of the equation was derived which was then reduced to a Laplace equation by a substitution. Considering appropriate boundary conditions, this equation was solved by a method of finite differences on an IBM 7040 computer. The method used in computation is solving a set of simultaneous equations by elimination. Less than two minutes machine time was required for a 39 by 39 matrix. Experimental results demonstrated fairly well the energy loss concept in surge wave considerations. The major energy loss at the wave front was assumed to be the expansion loss of the lower layer. The approximate solution holds for internal surge waves with small amplitude of any flowing area. A non-antisymmetric property was found during the mutual intrusion. That was quite contrary to the existing literature. No transient effect was apparent due to the limited length of pipe under investigation. An internal hydraulic jump was created by attaching a dam-shape barrier on the bottom wall of the pipe. A relation of conjugate depth ratio to the discharge ratio of the two phases was drawn by experimental results. / Ph. D.

The synthesis of a variety of polynuclear aromatic hydrocarbons by means of the condensation of grignard reagents with aromatic aldehydes did not always lead to the isolation of the desired diarylcarbinols. The delicate relationship between molecular structure and physiological activity demanded that only pure compounds of known structure be used in studying the carcinogenic and/ or carcinolytic effects of these aromatic hydrocarbons. Therefore, the above method of synthesis was eventually by-passed. But the apparently "abnormal" condensation of grignard reagents with aromatic aldehydes and the thermal decomposition of diarylcarbinols at high temperatures generated a great deal of interest from the mechanistic point of view, and these reactions were studied in detail in this work. The previously unreported ketones, 2-fluorophenyl 1-naphthyl ketone (52) and 2-fluorophenyl 2-naphthyl ketone (53), were prepared by the condensation of the cadmium reagents of 1- and 2-bromonaphthalene with 2-fluorobenzoyl chloride (51). Reduction of these ketones, 52 and 53, with a mixture of lithium aluminum hydride and aluminum chloride afforded the corresponding diarylmethanes, 2-(1-naphthylmethyl)fluorobenzene (56) and 2-(2-naphthylmethyl)fluorobenzene (57), respectively. Reduction of these same ketones, 52 and 53, with sodium hydroborate afforded the corresponding diarylcarbinols, 2-fluorophenyl-1-naphthyl carbinol (54) and 2-fluorophenyl-2-naphthyl carbinol (55), in good yield. The previously unreported 1-bromo-2-(1-naphthyl)naphthyl carbinol (45) was prepared by reduction of 1-bromo-2-(1-naphthyl) naphthyl ketone (44) with sodium hydroborate. This diarylcarbinol 45 was also prepared via the reaction of the Grignard reagent of 1-bromonaphthalene with 1-bromo-2-naphthaldehyde (41). The proof of structure of 45 was accomplished by studying the nuclear magnetic resonance and infrared spectra of 45 in conjunction with the nuclear magnetic resonance and infrared spectra of 1-bromo-2-(1-naphthyl)naphthyl carbinol-OD₁ (46) and 1-bromo-2-(1-naphthyl)naphthyl carbinol-CD₁ (47). The reported "abnormal" reaction of the Grignard reagents was investigated. The reaction of one equivalent of the Grignard reagent of 2-bromonaphthalene with one equivalent of 2-chlorobenzaldehyde gave the expected 2-chlorophenyl-2-naphthyl carbinol (37). The reaction of two equivalents of 2-chlorobenzaldehyde with one equivalent of the Grignard reagent of 2-bromonaphthalene gave 2-chlorophenyl 2-naphthyl ketone (36) by oxidation of the alkoxide complex formed by the initial condensation of the Grignard reagent with the aromatic aldehyde. The high temperature decomposition of diarylcarbinol 45 was found to lead to the formation of sym. -1-bromo-2-(1-naphthyl)naphthylmethyl ether (58). The structure of 58 was confirmed by molecular weight studies, infrared and nuclear magnetic resonance spectra and elemental analyses. The decomposition of ether at 58 240° was found to proceed slowly with the liberation of hydrogen bromide gas. Free radical initiators and hydrogen bromide gas were found to accelerate the decomposition of 58 at 240°. A reasonable mechanism has been postulated for the decomposition of 58 at 240°. The cleavage of ether 58 in the presence of hydrogen bromide gas would give rise to the formation of a secondary bromide, 1-bromo-2-(1-naphthyl)naphthylmethyl bromide (62). Homolysis of 62 would then give a bromine atom and a secondary free radical, 1-bromo-2- (1-naphthyl)naphthylmethyl free radical (63). The attack of free radical 63 on the benzylic hydrogen atoms of ether 58 is thought to be responsible for the formation of the diarylmethane, 1-bromo-2-(1-naphthylmethyl) naphthalene (48) and 1-brome-2-(1-naphthyl)naphthylmethyl ether free radical (64). Homolysis of 64 would then regenerate the secondary free radical 63 and the ketone 44. The coupling of two secondary free radicals 63, with subsequent attack of bromine atoms on the system, might give rise to the formation of di-[1-bromo-2-(1-naphthyl)naphthyl] ethylene (66). The attack of hydrogen atoms on 63 might lead to the formation of diarylmethane 48. Oxidation of ethylene 66 might give rise to the isolation of ketone 44. Evidence for these two reactions has been furnished by the vacuum distillation of secondary bromide 62. The attack of bromine atoms on the benzylic hydrogen atoms of ether 58 would give ether free radical 64 and hydrogen bromide gas. Homolysis of 64 would then give ketone 44 and secondary free radical 63. The decomposition of 58 would then appear to be cyclic in nature. The decomposition of diarylcarbinols 54 and 55 was judged to be free radical in nature, involving the formation of the two ethers, sym. -2-fluorophenyl-l-naphthylmethyl ether (67) and 2-fluorophenyl-2-naphthylmethyl ether (68), which decompose in the same temperature range as 54 and 55. Ethers 67 and 68 were not isolated. The decomposition of 67 and 68 was postulated to be a series of homolytic cleavages, giving rise to the formation of the diarylmethanes, 56 and 57, and the ketones, 52 and 53. / Ph. D.

An attempt was made to isolate L-N¹⁵-histidine from Escherichia coli cultured in a defined medium containing nitrogen-15 enriched ammonium salts as the only source of nitrogen. Commercially prepared L-N¹⁵-histidine.HC1.H₂0 was used to follow the limiting amino acid in the imbalanced diet in rats fed a chemically-defined imbalanced or corrected diet. Total nitrogen content and atom percent N¹⁵ were determined on the urine, gastrointestinal contents, diet, and the acid-soluble and protein fractions of the liver, kidneys, muscle, gastrointestinal tract, and serum at two, four, and six hours after the onset of feeding. The data were examined for changes in the concentration of N¹⁵ which might cause the imbalance phenomenon {reduced blood levels of the limiting amino acid). It was found that the limiting amino acid was not catabolized at an increased rate and that it was not absorbed or transported at a reduced rate due to the ingestion of an imbalance amino acid mixture. The increased efficiency with which the histidine was found to be incorporated into metabolically active proteins appears to be a primary cause of the reduced blood levels of the limiting amino acid and, therefore, of the imbalance phenomenon. Experimental verification was, therefore, obtained for the first unverified aspect of Harper's (12) thinking about the cause of the reduced appetite that is characteristic of the imbalance phenomenon. / Ph. D.

Experiments were conducted on the cellular responses of monocotyledonous and dicotyledonous plants to sublethal and lethal temperatures. The study had four objectives: I. to compare temperatures that develop in stems and leaves of plants under flame, II. to determine the effect of heat on conduction in the phloem (of stems), III. to investigate some cellular responses to sublethal and lethal temperature treatments, and IV. to determine the effects of lethal temperatures on respiration and on the Hill reaction. When stems and leaves of plants were exposed to a flame at 1900°F. for 130 milliseconds, there was a reduction in amount of heat that penetrated into stems of monocotyledon plants as compared to that penetrating into stems of dicotyledon plants. This difference in penetration appeared to be related to the morphology of the stem at the time of measurement. There were no differences between species tested in leaf tissue injury as indicated by degree-second summations. Heat penetrated less into stems than into leaves, and less into older plants than into younger plants. The temperature was higher at the stem periphery than near the stem center. C¹⁴ activity was greatly reduced in the roots of flame treated soybean plants when compared to the non-flamed plants 24 hours after the photosynthesizing parts of the plants had been exposed to C¹⁴O₂. The function of the sieve elements in conduction of the C¹⁴ photosynthates may have been temporarily blocked by the heat treatment. Loss of chlorophyll and swelling of chloroplasts were observed in cells of elodea leaves exposed to sublethal temperature treatments. At the thermal death point of leaf cells of elodea, corn, soybeans, pigweed, and yellow foxtail there appears to be a disorganization of the tonoplasts, plasma membrane, chloroplast membranes, and an irreversible stoppage of cytoplasmic streaming in leaf cells of elodea. Approximately 40 percent of the cells in elodea leaves show criteria of cell death at a temperature treatment which results in necrotic leaf tissue. Plasmolysis was observed in leaf cells at the lethal temperature treatments but did not appear to be a primary event at the cellular thermal death point. Changes in leaf cells of elodea after death were observed on certain days after the leaves had been exposed to lethal temperature treatments. In plasmolyzed cells of elodea leaves, observed immediately after treatment, there appeared to be chlorophyll in the cytoplasms and the chloroplasts appeared shrunken. The chloroplasts stained a dark blue in these cells (when stained with toluidine blue) indicating a disorganization of the chloroplasts. Cells observed two days after lethal temperature treatments exhibited slightly bleached chloroplasts, the cytoplasms appeared to be coagulated, and the plasma membranes appeared to be breaking down. The nucleus appeared to be still intact in some of the cells. Cells observed four days after lethal temperature treatments exhibited bleached chloroplasts with only remnants of the chloroplasts being apparent in some cells. The protoplasm in all the cells show characteristics of coagulation and the plasma membrane and the nuclear membrane appeared to be broken-up. A sublethal temperature treatment, which had produced chlorosis in vivo, reduced the Hill reaction of isolated soybean chloroplasts but not corn chloroplasts. Lethal temperature treatments reduced the rate of respiration of corn and soybean leaf discs to less than 50 percent of the rate of the control treatment. / Ph. D.

Three metabolism trials were conducted with wethers fed purified rations to study the effect of level of readily-available carbohydrates on cellulose digestibility. In the first experiment, two trials were conducted with fifteen wethers fed five rations. The basal ration contained 77.8% cellulose, 11.1% assay protein C-1, 7.2% minerals and 3.9% corn oil. Readily-available carbohydrates supplied by a 1:1 mixture of cerelose and starch replaced cellulose in the other rations to give levels of 2, 4, 6 and 8% readily-available carbohydrates. Level of readily-available carbohydrates in the ration failed to significantly affect digestibility of ration components and nitrogen balance. Cellulose digestibility tended to be higher for the 8% ration. Energy and dry matter digestibility tended to be higher for the supplemented rations. In experiment 2B, two metabolism trials were conducted with twelve wethers to study the effect of higher levels of readily-available carbohydrates on utilization of purified rations. The basal ration was of the same composition as that described above. Three additional rations contained 32%, 40% and 48% readily-available carbohydrates (levels were substituted for equal amounts of cellulose). Cellulose digestibility was 65.3% for the basal ration. Addition of 32, 40 and 48% readily-available carbohydrates significantly reduced cellulose digestibility. Increasing the level of readily-available carbohydrates from 32 to 40 and 48% reduced digestibility of cellulose (P < .05). Digestibility of total carbohydrates (cellulose and NFE) was 62.8%, 67.2%, 65.0% and 72.7% for the 0, 32, 40 and 48% rations, respectively. The difference between the 40% and 48% rations was significant. Nitrogen retention tended to increase in the supplemented rations, but the effect was not significant. Butyric acid content of the rumen fluid was higher in the supplemented rations. In the third experiment, fifteen wethers were fed three rations to determine the effect of level of readily-available carbohydrates on cellulose digestibility following preliminary periods of different lengths. The composition of the basal ration was the same as in experiments 1B and 2B. The other two rations contained 8% and 32% readily-available carbohydrates. There was a 10-day collection period following preliminary periods of 10, 20, 30, 40 and 50 days. There were no significant differences in ration digestibility or nitrogen utilization, regardless of the duration of the preliminary period. Regression analysis of data from four experiments involving 84 individual metabolism trials indicated that for each one percentage increase in readily-available carbohydrates in the ration cellulose digestion was significantly reduced 0.5 percentage units and nitrogen retention was not significantly altered. / Ph. D.

Absolute measurements, using the manganese bath technique and prompt-neutron coincidence calibration of fission counters, have been carried out to obtain independent evaluations the total yield of neutrons in thermal fission of U²³⁵[ν̅(U²³⁵)] and spontaneous fission of Cf²⁵²[ν̅(Cf²⁵²)]. In this experiment, the neutron-fission coincidence phase was used to calibrate only the fission counter efficiency; this calibrated fission counter was then inserted in a large manganese bath where the fission rate and neutron rate were simultaneously monitored. The absolute efficiency of the manganese bath was determined with the aid of a series of supplementary experiments, including frequent comparison of absolute 4π beta-gamma coincidence counting with the liquid radio-assay system. The over-all neutron detection efficiency relies heavily on the published manganese/hydrogen cross-section ratio, now known to about 0.3%. Corroboration of the neutron efficiency is found by obtaining a source rate of (1.185 ± 0.007) x 10⁶ neutrons/ sec for the U.S. National Bureau of Standards secondary source (NBS-II), which has a most recent best value (1.180 ± 0.012) x 10⁶ neutrons/sec. It is believed that this method is free of certain possible systematic errors, namely (1) a priori with regard to the fission neutron spectrum; (2) calibration of a detector whose sensitivity is comparatively neutron-energy dependent; and (3) angular anisotropy of neutron emission in flat-foil fission chambers. Examination of the literature and of data obtained from specific experiments indicates that this latter problem may be responsible for the relatively large scatter compared to the reported precision of published values of the U²³⁵ fission cross section and v̅. The results of this experiment, ν̅(U²³⁵) = 2.407 ± 0.03 neutrons/fission and ν̅(Cf²⁵²) = 3.750 ± 0.028 neutrons/fission, are highly consistent with weighted averages determined by international data compilation centers. / Ph. D.

Design requirements of fast reactors and theoretical studies which involve the optical model of the nucleus have increased the needs for neutron capture cross sections in the kev region. An indirect method to obtain these cross sections has been developed and applied to In¹¹⁵ and I¹²⁷ . Previous measurements of capture cross sections from a few kev to a few hundred kev and attempts to obtain average resonance parameters from analyses of these cross sections have not been entirely successful because they did not extend over a large enough energy range or because the normalizations to obtain absolute values were not completely satisfactory. Samples of In¹¹⁵, I¹²⁷, and Co⁵⁹ were activated in a well collimated beam of neutrons from the Virginia Polytechnic Institute UTR-10 nuclear reactor with varying thicknesses of B¹⁰ filters being interposed in the beam. The resulting data, representing activity versus filter thickness, were corrected for neutrons scattered from the beam and for neutrons with kinetic energies in excess of 100 kev. These corrected activation curves were then analyzed to obtain the average resonance parameters. Using the known thermal activation cross sections and the gamma ray strength function of I¹²⁷ as standards, the average s- and p- wave gamma ray strength functions <r_γ/D₀> l = 0 and <r_γ/D₀/> l = 1 have been calculated. From these average resonance parameters it was possible to calculate neutron capture cross sections for the two nuclides for neutron energies up to 100 kev. It was also possible to obtain the resonance integral of In¹¹⁵ I¹²⁷ relative to that of I and the s- and p- wave neutron strength functions of both nuclides. / M.S.

Years of research have been devoted to the understanding of the structure and nature of natural wind and to the development of theories which can be applied to the design of buildings and other structures. Extensive studies of the velocity profile of wind have been made from the ground to the stratosphere, but investigators have concentrated on the winds above thirty feet. It has been from the studies in excess of thirty feet that the most recent concepts for deriving design velocities have been obtained. Structures used in agricultural enterprises are usually low-profile structures being located in the lower thirty feet of the atmosphere. For this reason, this investigation was undertaken to measure the wind velocities in the lower thirty feet of the atmosphere and to develop a computer program whose output would be an equation for the vertical profile of the measured wind velocities. It was felt that this information would be of great value in the study of wind pressure distributions on a prototype building, and also in the wind tunnel model tests of the prototype. Velocity measurements were made with four pitot tubes mounted on a thirty-foot mast at intervals of eight feet along the mast. Velocity pressures were recorded instantaneously from all the pitot tubes by an oscillograph. The data recorded were entered into a computer program for multiple regression coefficients. The output was the intercept, K, and the slope, 1/α, for a velocity profile with an equation of the general form, V = KZ^1/α Where: V = velocity at height Z, K = intercept, 1/α = slope. The statistical analysis on the fit of the profile equation, obtained from the computer, to the velocities recorded for this investigation showed a high significance value. It was concluded that wind velocity measurements could be obtained by pitot tubes with reasonable accuracy in the lower thirty feet of the atmosphere, and that these velocity data could be entered into a computer program which would yield an output of a velocity profile equation that could be used with confidence. / M.S.

This thesis considers the effect of nonnormality, in terms of skewness and kurtosis, on the power of the analysis of variance test for a two-way classification, fixed effects model (with two replicates and no interaction). Most of the populations considered were only moderately non-normal, that is, only slightly peaked or skewed. We first considered the effect of a change in skewness for a fixed kurtosis. We then considered the effect of a change in kurtosis for a fixed skewness. In both cases, there was no significant deviation in power, as compared with the power in the normal case. The effect of non-normality on the power for an increase in both skewness and kurtosis for a particular Pearson Curve was then considered. A significant deviation in the power was found. The results indicate that for moderate departures from normality, the two-way classification, fixed effects model, is robust. / M.S.