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Thesis (Ph. D.)--University of Wisconsin--Madison, 1953. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 57-59).

Inaug.-diss.--Bonn. / Lebenslauf. Bibliographical foot-notes.

Modifications to the University of British Columbia Van de Graaff Generator have provided for the production of beams of singly-charged alpha particles. Alterations have been made to the ion source, analysing magnet, and reverse electron beam energy stabilizing system. Well-focussed beams of 10 to 15 microamps resolved of singly-charged alpha particles were available, at energies up to above 1.2 Mev. The nuclear reaction Li⁷ (∝,γ)f) B¹¹ was studied by bombarding targets of lithium metal evaporated onto copper backings. The gamma rays from the decay of states of B¹¹ were observed with NaI (Tl) scintillation counters and associated electronic equipment, including a 30 channel Marconi Pulse Amplitude Analyser. In the range of alpha particle energies available, three resonances were known for the capture of alphas by Li⁷ , forming states of B¹¹ at 9.28, 9.19 and 8.92 Mev. The decay of these states included cascades through lower excited states, in particular one at 4.46 Mev. The widths of these resonances were measured respectively as 8, 1 and <1 kev, in laboratory co-ordinates. The second of these values is significantly lower than previously reported. Measurements were also made of the yields of gamma radiation, and the angular distributions of certain gamma rays from each resonance. Experimental results and calculations have been compared with appropriate theoretical values to obtain information on the angular momenta and parity of certain of the B¹¹ states. The zero spin of the incoming alpha particles puts a useful limitation on the input channel spin. Assignments suggested by the data were as follows. For the 4.46 Mev state, 5/2⁻ ; for the 9.28 Mev state, 5/2⁺. Data for the 9.19 Mev state cannot distinguish between 3/2⁻~and 5/2⁻ , while for the 8.92 Mev state, the angular momentum would be restricted to 3/2 or 5/2 if the state was formed by the capture of p-wave alphas, but the parity was not determined. These results indicate that the states of B¹¹ are certainly more complex than the simple single-particle picture proposed by Jones and Wilkinson (1952), which is inadequate to describe the present results. Further investigation is invited. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The goal of this project is to design a feasible way to develop a protection plan for boron in the surface waters and groundwater of San Luis Obispo County. Boron is a micronutrient needed by all plants and animals but the threshold for toxicity in plants is narrow. As the need for water increases and the production of wastewater and irrigation water infiltrates the soil and waters of the County, an understanding of background soil and water concentrations, as well as anthropogenically produced sources of boron must be quantified and mapped so that intelligent planning decisions can be made. Many parties have interests at stake in understanding the nature of the threat posed by high levels of boron in soil and water. Water quality, as a resource, is essential for human health and a viable economy, especially if agriculture is a major economic resource. Many local, state, and federal agencies work in partnership to study, regulate, and implement change to the best management practices that protect and ensure water quality. This project will help evaluate the potential threat of elevated concentrations of boron in the waters of San Luis Obispo County and provide a usable resource that interested parties can reference with regard to this threat.

Thesis (Ph. D.)--University of Adelaide, Dept. of Plant Science, 1996. / Includes bibliographical references (leaves 234-256).

Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Soil and Land Systems, 2004. / "June 2004." Bibliography: leaves 135-159.

Presented as Thesis (Ph. D.)--University of Wisconsin--Madison, 1925. / Cover title. From Transactions of the American Electrochemical Society, vol. XLVII. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1961. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Although boron is an essential micronutrient for some plants, animals and humans, the range between deficiency and excess is narrow. The effects of excess boron on plants includes the reduction of root cell division, retarded shoot and root growth, inhibition of photosynthesis, deposition of lignin and suberin and decrease in leaf chlorophyll. A report by the World Health Organization (WHO) suggests a safe maximum level of boron daily intake of 13 mg/d an excessive level of boron can be toxic to and can causes serious diseases. There are several methods applied for boron removal from aqueous solutions and seawater. Among these methods, ion exchange, which is the most extensively method. Ion-exchange and adsorption are widely used techniques to remove metals and other solutes from aqueous solutions. This includes the removal of boron from reverse osmosis (RO) permeate in the process of seawater desalination. The use of boron-selective ion exchange resins based on macroporous polystyrene matrices with the active group N-methyl-D-glucamine (NMG) seems to still have the highest importance for the elimination of boron. Kinetics of adsorption or IEX is in many cases strongly influenced by diffusion resistance in particles of adsorbent. This resistance can be decreased by using smaller particles. Sorbents can be used as very fine particles which results in increase of the surface area and the process rate, considerably. Hybrid adsorption membrane filtration has gained the interest lately as it can be used for the removal of very small quantities of harmful substances from water. This thesis deals used hybrid system on both lab and pilot scale where a pilot plant was designed for the removal of boron. Boron separation combines two phenomena: i) sorption with fine sorbent particles and ii) membrane separation of B-loaded macromolecules/particles. The hybrid system includes two separation loops. Loop 1: Binding of boron (B) on Amberlite IRA743 resin (S), which is subsequently followed by separation of this (BS) complex from the water by means of semi-permeable microfiltration membrane. Here, pure water (W) is the main product whereas the complex (BS) passes to the second stage of separation. The effects of different parameters on boron removal using Amberlite IRA743 resin were investigated in this thesis. These parameters are, resin particle size, solution pH, temperature, contact time, initial boron concentration, resin concentration and the existence of different salts and ions like NaCl, Na2SO4 and MgCl2. The removal increased with increasing pH, temperature, contact time and resin dosage while it decreased with increasing initial boron concentration and resin particle size. For the microfiltration stage, three Polyvinylidene fluoride (PVDF) with different pore size have been used in this thesis. The effects of operational parameters like membrane pore size, transmembrane pressure, resin concentration and pH on permeate flux for hybrid adsorption-microfiltration were studied. The permeate flux increased with increasing the transmembrane pressure and pH but it decreased with increasing the resin concentration. The regeneration of loaded resin with boron was investigated. Hydrochloric acid (HCl) and sulfuric acid (H2SO4) at different concentrations have been used for the elution of boron from the saturated resin and then washing with sodium hydroxide (NaOH). There was an improvement in the boron removal after cycles of regeneration. The integrated adsorption-microfiltration was applied for boron removal from water and encouraging results were achieved.