8,196 research outputs found
Managing Market Pigs in Hoop Structures
No full textPork producers in the United States who are looking for lower cost structures for raising pigs have shown a great deal of interest in hoop structures or hooped shelters as facilities for housing market or finishing pigs. Producers need to be aware of the advantages and disadvantages of this type of housing.This article is published as Honeyman, Mark S., Frederick Wm. Koenig, Jay D. Harmon, Don C. Lay Jr., James B. Kliebenstein, Thomas L. Richard, and Michael C. Brumm. "Managing Market Pigs in Hoop Structures." Pork Industry Handbook. Michigan State University Extension Bulletin E-2713. January 2000. Posted with permission.</p
On the Michael addition of water to C = C bonds
No full text?-Hydroxy carbonyl compounds are an important class of compounds often found as a common structural motif in natural products. Although the molecules themselves look rather simple, their synthesis can be challenging. Water addition to conjugated C = C bonds opens up a straightforward route for the preparation of ?-hydroxy carbonyl compounds. Moreover, water addition to C = C bonds benefits a lot from its simplicity and excellent atom economy. However, the enantioselective addition of water to ?,?-unsaturated carbonyl (Michael) acceptors still represents a chemically very challenging reaction, due to the poor nucleophilicity of water and its small size, which make regio- and stereoinduction difficult. Equally, the often unfavorable equilibrium of water-addition reactions remains to be solved. In contrast, enzymes such as fumarase, malease, citraconase, aconitase, and enoyl-CoA hydratase have been successfully used on industrial scale, and their excellent (enantio-) selectivities are highly valued. Unfortunately, most hydratases are part of the primary metabolism where perfect substrate specificity is required. This very high substrate selectivity severely limits their practical applicability in organic synthesis. Thus, a straightforward approach with broad applicability still had not been described. The aim of the research presented in this thesis was to take up this challenge and dedicated to the search for a Michael hydratase with a more relaxed substrate specificity for the preparation of important ?-hydroxy carbonyl compounds. The stereospecificity of enzyme-catalysed reactions has been a fruitful source of information about the mechanisms of enzyme catalysis and vice versa; the application of stereospecifically labelled substrates allows for studying the course of the reaction. It offers a very promising opportunity to comprehensively understand the precise mechanistic and kinetic details of even the most complex enzymatic reactions. Thus Chapter 1 provides unifying ideas for stereochemistry of the enzymatic water addition to C = C bonds. This enhances our understanding of the chemistry of water addition to C = C bonds, and further allows us to find more hydratases from natural sources or obtained via protein engineering. In Chapter 2, a direct, enantioselective Michael addition of water in water to prepare important ?-hydroxy carbonyl compounds using whole cells of Rhodococcus strains is described. Good yields and excellent enantioselectivities were achieved with this method. This opens up an entirely new approach for the preparation of important ?-hydroxy carbonyl compounds. Deuterium labelling studies demonstrate that a Michael hydratase catalyzes the water addition exclusively with anti-stereochemistry, which belongs to the family members of hydratases: oleate hydratase, fumarase, malease, aconitase and type II dehydroquinase with a preference for the anti-addition; whereas, type I dehydroquinase, enoyl-CoA hydratase and artificial hydratase exclusive prefer for the syn-addition, as discussed in Chapter 1. The biocatalytic reaction system was carefully optimized for gram-scale synthesis, resulting in good conversions and excellent enantioselectivities. Under the optimized conditions, whole cells could be reused for 4 cycles without significant loss of activity while maintaining up to 90% ee. Since whole cells from Rhodococcus strains were used to catalyse the Michael addition of water in water to a series of ?,?-unsaturated carbonyl compounds, and when the work presented in Chapter 2 started, no genomic information of Rhodococcus strains was publically available, we sequenced and annotated the strain R. rhodochrous ATCC 17895. This is described in Chapter 3 together with features of the R. rhodochrous ATCC 17895. It is a Gram-positive aerobic bacterium with a rod-like morphology. The 6,869,887 bp long genome contains 6,609 protein-coding genes and 53 RNA genes. Our study suggests the Michael hydratase has not been described before. In the work presented in Chapter 2, we found that most ?-hydroxy ketones are not commercially available or commercially expensive as we mentioned in the first paragraph, which made the stereoselectivity determination of Michael addition products difficult. Indeed, many seemingly simple molecules have to be prepared via multi-step syntheses, in particular so if they are optically active. Therefore a straightforward approach to enantiomerically enriched (R)- and (S)-3-hydroxycyclopentanone was established by kinetic resolution in Chapter 4. This methodology allows us to prepare more ?-hydroxy carbonyl compounds structurally closely related to 3-hydroxycyclopentanone. The isolated chiral alcohols were used to determine the stereochemistry of the Michael addition of water in Chapter 2, saving us a lot of laboratory work. Moreover, unexpected stereoselective reduction of conjugated C = C bonds was discovered during studies on the enantioselective Michael addition of water. As mentioned in Chapter 2, the whole cells of R. rhodochrous ATCC 17895 reduced ?,?-unsaturated cyclic ketones into the corresponding ketones as initially undesired side reaction for the addition of water to C = C bonds. Therefore, ene-reductase activity was also investigated in Chapter 5. A series of substrates, including activated ketones, aldehydes, amines and nitro-compounds were screened for ene-reductase activity using whole cells of R. rhodochrous ATCC 17895. This showed that R. rhodochrous is a very promising catalyst for the reduction of C = C bonds and harbours ene-reductases. Indeed, looking for the annotated ene reductase from the genome of R. rhodochrous ATCC 17895 as described in Chapter 3, three candidates were observed and were classified as ene-reductases by amino acid sequence alignment with the known Old Yellow Enzymes (OYEs). Thus, the putative ene-reductase genes from R. rhodochrous ATCC 17895 were heterologously overexpressed in Escherichia coli and one of the encoded proteins was purified and characterized for their biocatalytic and biochemical properties. Based on these accomplishments it can be concluded that we have discovered a new Michael hydratase and three new ene reductases from Rhodococcus strains. Genome sequence and annotation of strain R. rhodochrous ATCC 17895 has been done, offering an excellent opportunity for the discovering novel enzymes, for instance, the Michael hydratase and S-selective ene reductase. The important chiral ?-hydroxy carbonyl compounds can be prepared by kinetic resolution of racemic alcohols using lipases or the direct enantioselective Michael addition of water using whole cells of Rhodococcus strains. The isolated products from kinetic resolution were readily used for the stereochemistry determination of Michael addition of water in water, completes the story of water addition to C = C bonds.BiotechnologyApplied Science
Michael Connelly Interview: 9/11, City of Bones, and Lost Light
No full textAn interview with American crime author Michael Connelly, exploring the role of crime narratives as outlets for critical engagement with the politics of the war on terror and the associated neoconservative narrativising of 9/11. The discussion principally delves into Connelly’s first two post 9/11 Harry Bosch novels; City of Bones (2002) and Lost Light (2003)
24th Annual African American Living Legends Series - Supervisor Burke and Michael Datcher
No full textCounty Supervisor Yvonne B. Burke (left) stands with event honoree author Michael Datcher (right)
24th Annual African American Living Legends Series - Michael Datcher and proclamation
No full textEvent honoree Michael Datcher signs the Living Legends proclamation at the 24th Annual African American Living Legends Series event honoring him and author Antwone Fisher
24th Annual African American Living Legends Series - Michael Datcher signs proclamation
No full textEvent honoree Michael Datcher signs the Living Legends proclamation at the 24th Annual African American Living Legends Series event honoring him and author Antwone Fisher
Postmodern Theory and the Choreography of Michael Clark
No full textThis study addresses two interrelated questions: Can postmodern ‘theory’ illuminate an understanding of Michael Clark’s work? and, a sub-question, In which ways, if at all, does Clark’s work demonstrate a postmodern sensibility? Chapter one, the introduction to this study, provides a ‘portrait’ of postmodernism, that is, it addresses the question What is postmodernism? Chapter two is a biography of Michael Clark. The seminal sections to this study, however, are chapters three and four. Here the author blends a discussion of a) subject matter, treatment and meanings in Clark’s choreography, b) journalistic criticisms of those features of his work, and c) postmodern theory. The outcome of these chapters is to demonstrate that Clark’s works do indeed require re-interpretation and re-evaluation, and to illustrate how these factors might be achieved
Tool for use in semi-automatic landslide mapping
No full textReport -- Maps.by Michael Bunn, Ben A. Leshchinsky, Michael J. Olsen, Nancy C. Calhoun, Jon J. Franczyk, and William J. Burns.This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Includes bibliographical references (pages 39-41).Mode of access: Internet from the Oregon Government Publications Collection.Text in English
How Does the Pre-weaning Environment Affect Gut Structure and Function, and Lifetime Performance of the Pig?
No full textThe reduction in feed intake and growth rate that occurs following weaning is of major economic consequence to the pig industry. Currently, a range of antimicrobial products can be used to minimise the impact of weaning on piglet health and subsequent performance. However, the use of these products in pig diets is subject to increasing restriction worldwide because of perceived risks to public health and to the environment. Thus, alternative methods are required to mitigate the growth check that almost invariably occurs after weaning in most production systems.
Piglets produced outdoors are claimed to experience less of a growth check at weaning and to be able to thrive in relatively unsophisticated weaner accommodation. However, these claims have not been substantiated under Western Australian conditions, nor a scientific basis for these claims established. Consequently, a series of experiments was designed to test the general hypothesis for this thesis – ‘the gut structure and function, and lifetime performance of the weaned pig are affected by its pre- and post-weaning rearing environments’.
Experiment 1 was conducted in two parts to quantify differences in the growth performance, health and gut structure of weaner pigs produced indoors or outdoors and reared in conventional or deep-litter pens. The weaner diet in the first part of the experiment contained 100 ppm of olaquindox and 3,000 ppm of zinc oxide (Exp1a). This experiment was repeated without using dietary antimicrobial products (Exp1b). Experiment 2 was conducted in conventional buildings to examine the effect of exposing piglets in lactation to similar substrates to those available to outdoor piglets used in Exp1a and Exp1b in the absence of other differences in the outdoor production milieu.
Pre-weaning environments in Exp1a (indoor production (IP) and outdoor production (OP)) appeared to have little effect on gut structure and overall growth rate but significantly affected carcass composition, whereas post-weaning environments (conventional (C) or deep-litter (DL)) affected both overall growth rate and carcass composition. Although feed disappearance was similar, OP pigs grew faster than IP pigs in the first 47 d after weaning in Exp1a but not in Exp1b. Lifetime growth rate (GR), P2 backfat, feed disappearance and feed conversion ratio (FCR) were not significantly affected by the production environment in Exp1a whereas OP pigs grew slower with higher P2 backfat and FCR in Exp1b. Interestingly, OP pigs had heavier carcass weights and higher dressing percentages than IP pigs in both parts of the experiment. The effects of post-weaning environment were more consistent as DL pigs grew faster, were fatter, and had higher carcass weights and dressing percentages than C pigs.
Villus height and crypt depth of IP and OP pigs were not different at 21 (weaning) or 28 d, but villus height decreased and crypt depth increased in the week after weaning. Pigs reared in C pens had greater faecal concentrations of volatile fatty acids than pigs in DL, indicating that the latter ingested sufficient straw to alter fermentation characteristics.
In Experiment 2, there were no differences in gut structure or pre-weaning and lifetime GR of pigs offered no creep feed (NC), a commercial creep feed (CF) or an ‘outdoor’ mix (OM) comprising of 1 part straw, 5 parts sow feed and 25 parts of soil taken from paddocks in which OP pigs used in Exp1a and Exp1b were farrowed. However, NC pigs grew slower in the week after weaning than the other two treatments. Backfat and feed disappearance were similar for all treatments but pigs on the OM treatment had higher carcass weights and dressing percentages than pigs on the NC and CF treatments. Villus height and crypt depth were not different between treatments and, although the piglets were weaned at 28 d, villus height decreased and crypt depth increased in the week after weaning to an extent similar to that experienced by piglets weaned at 21 d in Experiment 1.
Although all piglets received intramuscular injections of 200 mg iron (Fe) dextran when 1 to 2 days old, piglets offered the OM during lactation had higher serum iron and blood haemoglobin (Hb) levels than those offered NC or CF. Furthermore, half the piglets offered NC or CF had Hb levels indicative of chronic Fe deficiency anaemia. The average parity of sows used in this experiment was 6.3 litters, suggesting that piglets may have been born with low Fe stores, possibly because of low Fe stores in their dams due to sub-optimal mineral nutrition over successive parities.
In summary, the findings from these experiments partly supported the general hypothesis for this thesis. Under the conditions of these experiments, access to outdoor substrates in lactation had little effect on gut structure and lifetime growth rate but increased both carcass weight and dressing percentage, whereas rearing in DL pens increased feed intake, FCR, growth rate, P2 backfat, carcass weight and dressing percentage
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