The Composition of Arylstibonic Acids

This thesis describes a detailed ESI-MS investigation into the arylstibonic acids, organo-antimony-containing compounds that are currently of interest as anticancer reagents. Four arylstibonic acids, of nominal formula RC6H4SbO3H2 [R = p-chloro-, p-tolyl-, p-nitro- and α-naphthyl-] were synthesised, and a further eight archival samples from the National Cancer Institute Repository were obtained for use in the project. Results indicate clearly that the acids exist as polyoxometalate aggregates [H8(RSb)12O28], rather than monomeric species, in both the solid state and in acetonitrile solution, thus resolving a century-old debate concerning the nature of their molecular composition. Variations in solvent, time in solution and pH have also defined the stability of these aggregates under different conditions. Synthesis of arylstibonic acids by traditional methods (pre-1940) has been shown to lead to products contaminated with cations present during their preparation. An improved method of synthesis has been devised, and the crystal structure of an intermediate in the synthesis of these acids, [C6NH6][p-O2NC6H4SbCl5], is reported. Salts of arylstibonic acids with a range of cations were investigated by ESI-MS and shown to form a diverse family of polyoxostibonates with nuclearities including Sb12, Sb14 and Sb16. Crystal structures containing some of these aggregates, verified through parallel studies with collaborators, are described. Preliminary study of mixed polyoxometalates (Sb/As) showed a strong tendency to form As4Sb2 species but these could not be fully characterised

Formulating Mineral Supplements for Beef Cows

Mineral nutrition of beef cattle is one component of ruminant nutrition that most producers address by simply purchasing a commercial supplement for their herd. However, this practice, while generally effective, can be wasteful. In many cases, commercial mineral supplements are formulated to provide in excess of 100% of the nutrient requirements for many different minerals. However, at least a portion of the minerals required by beef cows are provided by the feeds the cows are consuming. The formulation of supplements to supply only what the animal needs may provide an opportunity for cost savings. This paper will describe the process of developing specifications that can be presented to a feed manufacturer to develop a mineral supplement

Feeding Corn to Beef Cows

In many western cattle operations, forages have traditionally been considered the most practical feedstuffs for wintering beef cows. However, in certain situations, the nutrient content of standing or harvested forages may be inadequate to meet the nutritional requirements of the beef cow for maintenance, gestation, or lactation. The availability of standing or harvested forages also may be limited, especially during drought years and(or) severe winters when the cost of medium- to low-quality forages may reach $80 to$100 per ton. Feeding corn grain may represent an economically viable alternative in each of these scenarios

Limit-Feeding Cows in a Drylot

Providing forage for cow herds is normally paramount to maintaining a desirable level of productivity. But during drought years, the supply of standing and harvested forages may be extremely limited and/or very expensive. Relocating the cow herd into drylot is a management alternative that may allow producers to take advantage of inexpensive grains and byproduct feeds to formulate cost effective cow diets

Effect of Harvest Method on the Nutrient Composition of Baled Cornstalks

This experiment was conducted to determine the effect of chopping corn residue prior to baling on the nutrient composition of cornstalk bales. One dryland corn field planted with a single variety of corn was used. After harvest, one half of the field was chopped with a stalk chopper. The remaining half was not chopped. Each half of the field was then raked into windrows, baled, and wrapped with plastic netting. Ten round bales were harvested from each half of the field (chopped and not chopped). Three core samples were then collected from each bale and pooled for analysis. Pooled samples were dried and analyzed for crude protein, crude fat, ash, acid detergent fiber (ADF), neutral detergent fiber (NDF), neutral detergent insoluble nitrogen (NDIN), lignin, calcium (Ca) and phosphorus (P). Total digestible nutrients were then calculated from the analyses. Neutral detergent insoluble nitrogen was greater (P \u3c 0.01) in chopped cornstalks than in cornstalks that had not been chopped. Calcium concentrations were greater (P \u3c 0.05) and phosphorus concentrations tended to be greater (P \u3c 0.10) in chopped cornstalks than in those that had not been chopped. The remaining nutrients were not affected by processing. Chopping cornstalks prior to baling did not negatively affect their nutritional value for beef cattle. However, because of differences in varieties, growing conditions, and agronomic practices, caution should be exercised in extrapolating these results

Thermo-Mechanical System Identification of a Shape Memory Alloy Actuated Mechanism

Shape memory alloy (SMA) actuators paired in an antagonistic arrangement can be used to produce mechanisms that replicate human biomechanics. To investigate this proposal, the biomechanical articulation of the elbow by means of the biceps brachii muscle is compared with that of a SMA actuated arm. This is accomplished by parametric analysis of a crank-slider kinematic mechanism actuated, first, with an experimentally characterized SMA wire and then an idealized musculotendon actuator based on actuation properties of muscles published in the literature. Next, equations of motion for the system dynamics of the SMA actuated mechanism are derived and phase portrait analysis is conducted varying system parameters around different operating points. The eigenvalues of the differential equation are examined around equilibrium points and a stiffness ratio metric is proposed to characterize dynamic stability based on system parameters. Next, a heat transfer model is proposed and energy analysis is conducted on each stage of phase transformation for the SMA wire. The unknown parameters in the heat transfer model are theoretically derived and an experimental system identification is conducted. A proof of concept antagonistic SMA actuated mechanism is designed and kinematic analysis is conducted on an experimental prototype

Arylstibonic acids [H₈(RSb)₁₂O₂₈]; precursors to organometallic isopolyoxostibonates [Na₂H₉(RSb)₁₂O₃₀]-, (R = aryl).

Electrospray ionisation mass spectrometry shows that arylstibonic acids, RSbO₃H₂, give rise to oxo-bridged clusters derived from [H₈(RSb)₁₂O₂₈] which act as inorganic crown ligands towards Na+ cations; structure determination of one derivative revealed a cage-like anion [Na₂H₉(p-O₂NC₆H₄Sb)₁₂O₃₀.4H₂O]-

Effects of the Environment on the Nutritional Needs of Grazing Livestock

Profitability of grazing operations is related to productivity per acre. Productivity is determined, among other factors, by the efficiency with which the animal harvests the forage. Efficiency can be defined as nutrients consumed per unit of product produced (feed to gain). Costs incurred in this process which are not translated into products are sources of inefficiencies. Costs are not only related to dollars spent by livestock producers but also to nutrient inputs and outputs (balance) incurred by an animal. Just as in your bank account, the animal has a budget in his body with accretions and withdrawals, and when one exceeds the other they can either build up or deplete reserves. Nutrients consumed by cattle provide maintenance and production. Energy, one of the most critical nutrients for grazing ruminants, is supplied by the end products of nutrient fermentation and absorption. Energy is used to maintain body temperature, is lost as heat of fermentation, or is used while performing work (e.g. walking). An energy balance is the result of the difference between inputs (energy intake) and outputs (energy expenditure).When positive, it may result in body weight gain and increased production and reproduction. A negative energy balance, on the other hand, can decrease production and/or body condition and ultimately affect fertility

Grazing Corn Stalks

It has been known for years that one of the largest expenses in a beef cattle production system is feed, more specifically, winter feed. Consequently, a great deal of research has focused on ways—shifting the production system to better fit the forage resource base, feeding cheaper alternative feeds and forages, extending the grazing season—to reduce winter feed cost. In the upper Midwest with its short growing season for grasses and significant amount of snowfall received in a typical year, crop residue is the most cost-effective method to extend grazing. Extending the grazing season without adding additional forage acres or substantial cost offers beef cattle production systems a competitive advantage

Distillers Co-products for Beef Cows and Heifers

In recent years, the expansion of corn-based ethanol production has resulted in an abundance and variety of co-product feedstuffs. As research with distillers co-products has evolved, findings have indicated that the value of the protein and energy content of these feeds is suitable for use in beef cattle diets. In an era of volatile feed costs, these feeds can alleviate some of the burden of high grain prices. The biggest concerns in feeding these products to beef cattle are the potential for high sulfur and phosphorus concentrations, variation in nutrient composition as it changes relative to source and season, and the need for adequate storage facilities and handling equipment to avoid spoilage and loss