Thesis (Ph. D.)--University of Wisconsin--Madison, 1944. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [134]-144).

Thesis (M.A.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 73-74).

Thesis (M.S.)--University of Wisconsin--Madison, 1962. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 129-131)

The structures of four di-(tertiary arsine) derivatives of metal carbonyls have been determined by a selection of direct, Patterson, and Fourier methods, applied to Mo-[formula omitted] diffractometer data. 1,2- bis(dimethylarsino) tetrafluorocyclobutene-tri-iron decacarbonyl, Me₂AsC=C(AsMe₂) CF₂CF₂ .Fe₃ (CO)₁₀, crystallizes in the monoclinic space group P2₁/c, with a = 11.60, b = 20.04, c = 22.11 Å, β = 93.7°, Z = 8 (two molecules per asymmetric unit). The structure was refined by least-squares procedures (a total of 74 atoms) to a final R of 0.09 for 2524 observed (of a total of 3234) reflections. The molecule is best described as a derivative of Fe₃(CO)₁₂, in which one terminal carbonyl group on each of the two equivalent iron atoms is replaced by an arsenic atom of the di-(tertiary arsine) ligand. The central Fe₃As₂ cluster is significantly bent in one of the molecules of the asymmetric unit, but is more nearly planar in the other molecule. The Fe-Fe bond distances in the iron triangle (2.53,2.65,2.65 Å) do not differ significantly from those in the parent compound. Crystals of bis(1,2- bis(dimethylarsino)tetrafluoro cyclobutene)triruthenium octacarbonyl,(Me₂AsC=C(AsMe₂)CF₂CF₂)₂. Ru₃(CO)₈, are orthorhombic, space group Pbcn, a = 9.07, b = 18.53, c = 21.81 Å, Z = 4 (one-half molecule per asymmetric unit). The structure was refined by least-squares procedures to a final R of 0.078 for 1507 observed (of a total of 1712) reflections. The molecule lies on a crystallographic two-fold axis, and is best described as a derivative of Ru₃(CO)₁₂ in which two carbonyls on one ruthenium and one carbonyl on each of the other ruthenium atoms are replaced by the arsenic atoms of the bidentate di-(tertiary arsine) ligands, in such a way that each ligand bridges two ruthenium atoms, and one Ru-Ru bond remains unbridged. This unbridged Ru-Ru bond (2.785 Å) is significantly shorter than the bridged ones (2.853 Å) and than those of the parent Ru₃(CO)₁₂ (average 2.848 Å). The skeletons of the di-(tertiary arsine) ligands do not deviate significantly from exact planarity, the plane of each ligand being twisted 18° with respect to the plane of the ruthenium triangle. The mean Ru-As bond length is 2.407 Å. 1,2- bis(dimethylarsino)tetrafluorocyclobutene-triruthenium decacarbony1, Me₂AsC=C(AsMe₂)CF₂CF₂.Ru₃(CO)₁₀, crystallizes in orthorhombic space group. P2₁2₁2₁, a = 8.594, b = 18.795, c = 16.69 Å, Z = 4. The structure was refined by least-squares procedures to a final R of 0.076 for 1828 observed (of a total of 2028) reflections. The compound is a derivative of Ru₃(CO)₁₂ in which one equatorial carbonyl group on each of two ruthenium atoms is replaced by an arsenic atom of the di-(tertiary arsine) ligand in such a way that the plane of the ligand is twisted 18° with respect to the plane of the ruthenium triangle. Ru-Ru bond distances are 2.831, 2.831, and 2.858 Å, the difference between the short and long bond lengths being statistically significant and explicable in terms of the bonding characteristics of the ligand. 1,2- bis(dimethylarsino)hexafluoropropanemolybdenum tetracarbonyl, Me₂AsCF(CF₃)CF₂AsMe₂.Mo(CO)₄, crystallizes in the monoclinic space group C2/c, a = 25.06, b = 13.27, c = 11.56 Å, 6 = 102.8°, Z = 8. The structure was refined by least squares methods to a final R of 0.073 for 1510 , observed (of a total of 1750) reflections. The molecule is derived from Mo(CO)₆by replacing two carbonyl groups with the arsenic atoms of the chelating di-(tertiary arsine) ligand. Two of the carbon-fluorine bond distances (mean 1.505 Å) are significantly longer than the others (mean 1.30 Å) and the distance between the carbon atoms of the ligand skeleton is remarkably short (1.40). The weighted mean Mo-As bond length is 2.572 Å. / Science, Faculty of / Chemistry, Department of / Graduate

A three-dimensional finite difference code was developed to simulate fluid flow and heat transfer phenomena in continuous casting processes. The mathematical model describes steady state transport phenomena in a three dimensional solution domain that involves: turbulent fluid flow, natural and forced convection, conduction, release of latent heat at the solidus surface, and tracing of unknown location of liquid/solid interface. The governing differential equations are discretized using a finite volume method and a hybrid central, upwind differencing scheme. A fully three-dimensional ADI-like iterative procedure is used to solve the discretized algebraic equations for each dependent variable. The whole system of interlinked equations is solved by the SIMPLE algorithm. The developed computer code was used for parametric studies of continuous casting of aluminum. The results were compared against available experimental data. This numerical simulation enhances understanding of the fluid flow and heat transfer phenomena in continuous casting processes and can be used as a tool to optimize technologies for continuous casting of metals. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

An improved method for preparing (L-L)Fe2(CO)6 complexes (L-L is a fluorocarbon-bridged ditertiary arsine or phosphine) has been developed. The reactions of these complexes with monodentate L and bidentate L-L ligands give rise to eight types of products. These include L[sup m](L-L)Fe2(CO)5 and (L-L) [sup m] (L-L)Fe2(CO)5 in which the mono-dentate ligand replaces one carbonyl group from Fe[sup A]; (L[sup m])2[sup s] (L-L)Fe2(CO)4 c A and (L-L) (L-L)Fe2(CO)4 in which two carbonyl groups on Fe have been replaced; (Lm)2(L-L)Fe2(CO)^, (L-L)b(L-L)Fe2(CO) and (dppp) [sup B] (L-L)Fe2(CO)4 in which one carbonyl group on each iron has been replaced; and (Lm)3(L-L)Fe2(CO) in which the ligands replace two carbonyl groups from Fe[sup A] and one from Fe[sup B] . The spectroscopic properties and some reactions of these derivatives are described. The reactions of Co2(CO)8 and (ir-alkyne)Co2(CO)6 with some monodentate and bidentate ligands and that of [LCo(CO)3]2 with bidentate ligands have been investigated. Several new compounds have been isolated; these include bridged derivatives (L-L) [sup b]2Co2(CO) [sup t]2(C0) [sup b]2 and L(L-L) [sup c]Co2(CO)3[sup t] (CO) [sup b]2, non-bridged derivatives (L-L)Co2(CO)^[sup t]7and [(L-L)Co(CO)3]2, ionic products [L2(L-L)Co(CO)]2+[sub 2](X⁻)2 and L4(L-L)Co2(CO)4[sup 2+](X⁻ )2, and substitution products L[sub n](RC = CR)Co2(CO)[sub 6-n](n = 1-4), (L-L)[sup c][sub 2](RC = CR)Co2(CO)4> (dppp)°(RC = CR)Co2(CO)2 (L-L)b2(RC = CR)Co2(CO)2 and (L-L)2(RC = CR)Co2(CO)2. The proposed molecular structures are based on chemical and spectroscopic information. In parallel with the preparative work, 59Co nqr studies on cobalt carbonyl complexes have been carried out. The effects of Y on the nqr spectra of the [Y3PCo(CO3)2 (Y = oph, 0Me, 0Et> Bu[sup n]) compounds are found to be both inductive and conjugative. The coupling constants of the L2Co(CO)+3X (L = Ph3P; X = Co(CO)4, BPh4) compounds appear to be insensitive to the formal oxidation state of the Co atom. The spectra of some substituted derivatives of Co2(C0)8 have been interpreted z o in the light of their structures. The nqr data of (RC = CR')Co2(CO)6 (R = R' = H, CH2OH, Ph, CF3; and R = Bu[sup t], R' = H) are found to be sensitive to the inductive and conjugative effects of the R and R' groups. Some 35Cl nqr studies on fluoroalicyclic YC = CC1(CF2)n (Y = substituent, n= 2 to 4) compounds were also undertaken. The 35 Cl nqr frequencies of these compounds are roughly related to the electronegativity of the substituents Y and to the ring size, suggesting that the inductive effect is the main factor responsible for the change. It also seems that the substituents F, OMe, N3, Me2 show both inductive and conjugative effects. / Science, Faculty of / Chemistry, Department of / Graduate

Fluid flow through liquid interdendritic channels of a partially remelted lead-tin casting has been measured directly, with gravity as the driving force. The results were shown to be consistent with Darcy's Law. The permeability of the dendritic array was found to be a function of the square of the primary dendrite spacing, and was observed to increase with time due to coarsening of the dendritic structure. The formation of casting defects in lead-tin alloys was studied with isothermal and unidirectional solidification experiments. Solute convection was observed when the liquid close to the bottom of the solid-liquid region was less dense than the liquid above, using radioactive tracer techniques. Macrosegregation was shown to be related to the solidification conditions, and channel-type defects, resembling freckles and A segregates, were formed when the rising interdendritic liquid dissolved dendrite branches in its path. A simple mathematical model is proposed, which predicts the composition profiles in vertical, directionally solidified lead-tin castings, as a function of the structure, growth rate, and temperature gradient. The model is shown to agree qualitatively with the experiments, and can be used to recommend specific changes in casting practice to reduce gravity segregation effects. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

The visioplasticity approach is developed to enable the complete stress history of any steady or non-steady, quasi-static or impact, plane strain plastic deformation process to be determined from a record of the deformation pattern. The velocity field is determined experimentally and for dynamic conditions high speed photographs are taken of a grid pattern marked on the end surface of the specimen. Digitization of the instantaneous grid node positions allows the velocity fields to be obtained at predetermined time intervals throughout the transient deformation period. Hence, the strain-rate, equivalent strain rate, equivalent strain and finally stress fields can all be obtained. A three dimensional surface fitting procedure, using fourth order polynomials, is used to smooth the scalar component of the experimentally determined velocity field. The condition of continuity (Є [sub x]=- Є [sub y], for plane strain), is imposed on both surfaces thereby reducing the number of independent parameters from 30 to 10. Besides smoothing the experimental points this procedure has the distinct advantage that the polynomials can be readily differentiated for determining strain-rates and that deformation can be referred to a master reference grid that is fixed with respect to time. Plane-strain upsetting tests, conducted at a speed of 0.02 ft/min give results that agree closely with the well documented 'friction hill' type of normal stress distribution for quasi-static rates of strain. However, with the specimen deformed at a speed of 15.7 ft/sec the normal stress distribution is radically different exhibiting a saddle type distribution. The effect of strain rate on the interface and body stresses will have significant bearing on a number of metal forming operations. / Applied Science, Faculty of / Mechanical Engineering, Department of / Unknown

Seeds, especially cereals and legumes are a vital component of the human diet and as a result of elevated levels of environmental pollution, seed-bearing crop plants are grown increasingly on contaminated soils. Although several studies have looked at seeds as potential sources of metals that may enter the food chain, very little research has been carried out to examine the effect of such toxicants on the physiology of these plant parts. This study examines the effect of two metal pollutants, namely Cd and Ni, on the development and functioning of soybean seeds. Cadmium was chosen because it is considered to be the most serious of the metal pollutants, is highly toxic to mammals and easily enters the food chain. Nickel, is relatively mobile within plants compared to other metal pollutants and also represents a potential threat to the environment. Soybean plants (cv Crawford) were grown to maturity in a circulating nutrient solution system, which in the case of treatment plants, was amended with either Cd or Ni. From the results of preliminary trials in which the effect of metal pollutant concentration on plant growth and pod production were examined, nutrient solution concentrations of 0.05 mg Cd/litre or 1 mg Ni/litre were used for routine cultivation of the plants (termed metal-treatment plants). Seeds were harvested at four (initially five) different growth stages and the effect of the metal pollutants on size and other developmental parameters investigated. Accumulation and distribution of Cd, Ni and other elements within the seeds was examined. Firstly, by using inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and secondly, at a finer resolution utilising a nuclear rnicroprobe, coupled with proton induced X-ray emission (PIXE). The anatomy and ultra-structure of metal pollutant-treatment seeds was compared with that of control seeds using light as well as transmission electron microscopy (LM and TEM). Possible structural aberrations caused by the presence of Cd or Ni were identified. In another set of experiments, seeds were germinated in solutions of different concentrations of Cd or Ni (termed metal-germinated seeds). The LCso and ECso values for germination and radicle extension respectively, were derived. The effect of metal pollutants on seedling establishment was also examined by cultivating the plants further in nutrient solution containing different concentrations of the metal pollutants. Other seedlings (termed recovery seedlings), subsequent to germination in the metal pollutant, were transferred to the standard control nutrient solution. Uptake of metal pollutant, concentration of photosynthetic pigments and photosynthetic functioning were examined in metal-germinated, recovery and control seedlings. In the final section of the study, chemical speciation in the nutrient solution used for cultivation of metal-treatment plants was modelled using the speciation software MINTEQA2. Percentage bioavailability of the metal pollutants as well as of four nutritionally important metals, Fe, Mn, Mg and Zn was examined. Furthermore, computer simulations were also carried out to model the effect of pH and increasing metal pollutant concentration, on the bioavailability of the abovementioned metals. Addition of even low concentrations of Cd or Ni to the nutrient solution resulted in reduction in root biomass and pod (and hence seed) production. This effect increased with metal pollutant concentration. Cadmium appeared to be more phytotoxic than Ni and lower concentrations of the former were required elicit an equivalent response. Visual toxicity symptoms noted, included red pigmentation in the petioles, chlorosis of the trifoliate leaves followed by the appearance of necrotic areas. In addition, Ni-toxicity symptoms included terminal deformed pods, as well as red spots in the inter-veinal areas of leaves. Both Cd and Ni accelerated plant senescence. Leaf abscission was promoted and in the case of the older growth stages, the rate of pod development was increased relative to that of control pods. Nonetheless, the presence of metal pollutants did not appear to enhance pod abscission during the developmental period examined. In metal-treatment plants, pollutant loads in roots were much higher than in shoots. Cadmium levels in the seeds harvested from these plants were extremely low (approximately 1µg/g.dm) indicating that the metal is excluded from these tissues to a great extent. Nickel was more mobile than Cd, reaching higher levels than the latter in all plant parts and a concentration of approximately 50 µg/g.dm in mature treatment seeds. Pods did not appear to exclude entry of metal pollutants into the seeds and contained similar concentrations as the seeds in the case of Cd and lower concentrations in the case of Ni. Seed concentration of both metal pollutants (when expressed as µg/g.dm) was highest in the youngest growth stages and then decreased with age. Cadmium was found to decrease mean seed size relative to control seeds, but had no effect on the number of seeds per pod. Nickel on the other hand, exerted no effect on size but did reduce the average number of seeds contained in each pod. As a result of reduced mass, the presence of Cd in the nutrient solution reduced the lipid, starch and total N content of seeds harvested from soybean plants grown in such a medium. No significant effect on the quantity of storage reserves could be detected in Ni-treatment seeds. Mature seeds harvested from Cd-treatment plants had lower Fe and Mn, but higher Zn and Mg contents than control seeds. Nickel-treatment seeds also exhibited reduced Fe, Mn and elevated Zn contents, but Mg levels were also reduced. Shifts in seed concentrations of the nutritionally important metals noted above, were also found in pods, most notably a reduction in Fe content. Despite the presence of metal pollutants within the seeds, the extent of germination in metal pollutant-treatment seeds was not impaired compared to control seeds. The rate of germination, however, was depressed slightly in both metal treatments. Examination of metal distribution within seeds using ICP-AES revealed that Cd was localised mainly in the testa and cotyledons, with very little in the axis. Nickel was mainly concentrated in the axis and least in the cotyledons. Cadmium levels in metal-treatment seeds were too low for distribution maps to be made using PIXE and only point analyses were carried out. Overall, these results agreed with those obtained from ICP analysis. Nickel, which accumulated to higher levels within seeds, was mapped successfully using PIXE. The embryo axis appeared to contain the highest concentrations of Ni, particularly in the apical meristem and cortex, but was virtually absent from the root cap area and the central stele. Interesting elemental maps were also obtained for S, Fe and Mn (supplied in the nutrient solution at normal physiological concentrations). Levels of Ni in control seeds were extremely low and could not be mapped. The LC50 and EC50 values for germination and radicle elongation respectively, in the presence of exogenous metal pollutant, were found to be lower for Cd than Ni. This is consistent with the higher phytotoxicity of the former element. Radicle elongation was found to be more sensitive to the presence of exogenous metal pollutants than seed germination. The major effect on seedling establishment was reduction in growth, particularly of the lateral roots. As in the case of mature plants, pollutant loads in the roots of seedlings were higher than in shoots. Recovery seedlings appeared relatively healthy after a period of exposure to metal pollutants, up to a critical concentration of metal pollutant. Nonetheless, although little reduction in the concentration of photosynthetic pigments or the efficiency of photosynthetic functioning was recorded, two weeks after exposure to the metal pollutants, root biomass was still reduced relative to that of control seedlings. The total chlorophyll content of metal pollutant-germinated seedlings decreased at low concentrations of the metal pollutants, but then increased at higher concentrations. It is suggested that this is the result of the combined effects of inhibition of photosynthetic pigment synthesis, coupled to reduced leaf expansion. Metal pollutant-treatment and control seeds did not differ from each other in external appearance nor at the LM level. Slight ultra-structural variations were noted using TEM however, including the presence of vesicles in the nucleoplasm of Cd-treatment cotyledon cells, an increase in the number of crystalloid inclusions in protein bodies (possibly phytate) as well as an increased number of starch grains in the radicle tip cells of Ni-treatment seeds. Further research is needed to confirm these results. Significant ultra-structural changes in metal pollutant-germinated seedlings were noted compared to the controls. From examination of the ultra-structure of such seedlings, both Cd and Ni appeared to affect nuclear functioning, proteolysis, as well as starch grain formation. Cadmium elicited a response at lower concentrations than Ni. It is stressed that these are not necessarily the principal toxic actions of the metals however, as marked structural changes were apparent only at high concentrations. Aberrations to cytoplasm adjacent to the cell wall were also noted in cells from seedlings germinated in the presence of Ni. Computer speciation simulations using MINTEQA2 predicted that in the respective treatment solutions, 87% of Cd, but only 49% of Ni, was in a form suitable for plant uptake. Shifts in seed contents of Mg, Mn and Zn, in response to amendment of the nutrient solution with metal pollutants, could not be explained by changes in chemical speciation in the growth medium. The decrease in Fe content in Ni-treatment seeds on the other hand, may possibly be a consequence of decreased bioavailability of this ion in the nutrient solution. pH was found to exert an effect on the speciation profile of metal pollutants, as well as on that of nutrients. The most marked effect was noted on Nt2. The proportion of metal in this form (the bioavailable form) decreased from 49% to 3% when pH was increased from 6.0 to 7.0. Although plants are able to limit entry of metal pollutants into seeds to some extent, they do still enter these tissues and it is important that the effects on functioning of such plant parts be examined. This study reports preliminary findings on this aspect. Much work remains to be done however particularly with regard to the effect of metal pollutants on the quality of storage reserves, especially proteins. Furthermore, this work should be extended to the seeds of other important crop plants.

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