Block co-polymerization by transformation reactions

The aim of this study was to use the transformation of anionic to metathesis polymerization to produce block co-polymers of styrene-b-pentenylene using WC16 /PStLi and WC16/PStLi/ AlEtC12 catalyst systems. Analysis of the products using SEC and 1H and 13C NMR spectroscopy enabled mechanisms for metathesis initiation reactions to be proposed. The initial work involved preparation of the constituent homo-polymers. Solutions of polystyryllithium in cyclohexane were prepared and diluted so that the [PStLi]o<2x10-3M. The dilution produced initial rapid decay of the active species, followed by slower spontaneous decay within a period of days. This was investigated using UV / visible spectrophotometry and the wavelength of maximum absorbance of the PStLi was found to change with the decay from an initial value of 328mn. to λmax of approximately 340nm. after 4-7 days. SEC analysis of solutions of polystyrene, using RI and UV / visible (set at 254nm.) detectors; showed the UV:RI peak area was constant for a range of polystyrene samples of different moleculor weight. Samples of polypentenylene were prepared and analysed using SEC. Unexpectedly the solutions showed an absorbance at 254nm. which had to be considered when this technique was used subsequently to analyse polymer samples to determine their styrene/ pentenylene co-polymer composition. Cyclohexane was found to be a poor solvent for these ring-opening metathesis polymerizations of cyclopentene. Attempts to produce styrene-b-pentenylene block co-polymers, using a range of co-catalyst systems, were generally unsuccessful as the products were shown to be mainly homopolymers. The character of the polymers did suggest that several catalytic species are present in these systems and mechanisms have been suggested for the formation of initiating carbenes. Evidence of some low molecular weight product with co-polymer character has been obtained. Further investigation indicated that this is most likely to be ABA block copolymer, which led to a mechanism being proposed for the termination of the polymerization

Let\u27s Cure Cancer!

From ancient Egypt to modern times, scientists have been learning new ways to prevent, diagnose, and treat cancer. In this book, you’ll learn about cancer and how veterinarians, veterinary technicians, physicians, and other scientists are working together to find a cure for cancer in people and their pets.https://docs.lib.purdue.edu/vetbooks/1003/thumbnail.jp

5th Grade Veterinary Medicine Activity Book - English Edition

The objective of this book is to provide career-based activities for students in grade 5. This book incorporates Indiana Academic Standards for Math, English/Language Arts, and Science.The activities in this book are intended to educate students into considering veterinary medicine as a potential career choice.https://docs.lib.purdue.edu/vetbooks/1004/thumbnail.jp

Navigating Diversity and Inclusion in Veterinary Medicine

This book addresses the continued lack of the diversity in veterinary medicine, the least inclusive of all medical professions. Effective navigation of the complexity of diversity and inclusion in veterinary medicine requires clear enumeration, recognition, and understanding of key issues, challenges, and opportunities. In a nation with rapidly changing demographics, public needs and expectations of the veterinary profession will continue to evolve. A more diverse scientific workforce is required to feed the veterinary profession, not just for the purposed of equity, but as necessity for its sustainability and relevance.The book lays out the history of diversity in the veterinary profession, in the context of historical changes and actions within US society. An overview of selected strategies from dental, pharmacy, and (human) medical schools is then offered. The impact of social constructs on career interest development is explored using the examples of race, gender, sexual orientation, and gender identity. Practical strategies for attracting preschool through undergraduate students to careers in the veterinary profession are presented, as well as metrics and tools to assess the impact of diversity and inclusiveness strategies. A systems approach to diversity and inclusiveness in the veterinary profession is called for in a manner that frames barriers as opportunities for improvement and progress. There is much that needs to happen to achieve professional inclusiveness and cultural competency, but the path to achieving this is clear. System-wide commitment, planning, execution, and continuous assessment will position the profession to better suit the population of the nation and the world that will be served. This is book is a call to action for consistent championship and cohesive approaches, and it provides a road map to building a sustainably inclusive future.https://docs.lib.purdue.edu/ndhab/1002/thumbnail.jp

Why aren't more veterinary practices owned or led by women?

The increasing proportion of women among the body of UK veterinary surgeons practicing clinical medicine has been consistently highlighted in RCVS surveys (RCVS 2006, 2010, 2014a). Despite women outnumbering men in clinical practice (57% v 43%) in 2014 (RCVS, 2014a) they do not own veterinary practices or hold practice partnerships or leadership positions in proportions that may be expected, even when adjusting for age and experience (RCVS, 2014b)

Mechanical Transmission of Enterotoxigenic Escherichia coli to Weaned Pigs by People, and Biosecurity Procedures that Prevented such Transmission

Objectives: To determine whether people can mechanically transmit enterotoxigenic Escherichia coli (ETEC) from infected to susceptible weaned pigs during direct pig contact and to determine biosecurity measures that will prevent such transmissions. Materials and Methods: One hundred and twenty-five 19- to 21-day-old weaned pigs, culture-negative fro ETEC M1823B, were randomly allocated to six treatment groups housed in five separate isolation rooms. Inoculated Pigs were offered 1.36 x 1010 to 8.92 X 1010 colony forming units of E coli mixed in strawberry gelatin on two occasions. Pen Sentinels were housed with Inoculated Pigs. A caretaker fed pigs, checked waterers, and directly contacted each group of pigs for 10 minutes daily for 10 consecutive days. THe caretaker contacted Inoculated Pigs and moved directly to Direct Sentinels, recontacted Inoculated Pigs, washed hands twice, changed outer-wear, then contacted Hand-wash Sentinels. The caretaker then recontacted Inoculated Pigs, showered, changed outerwear, and contacted Shower Sentinels. Non-exposed pigs had a separate caretaker. Results: Escherichia coli M1823B was isolated from all 20 Inoculated Pigs, all five Pen Sentinels, 20 of 25 Direct Sentinels, and 23 of 25 Hand-wash Sentinels. The 25 Shower Sentinels and 25 Non-exposed Pigs remained culture-negative for M1823B. Implications: In this study, people mechanically transmitted E coli without extraordinary measures to enhance caretaker contact with pig excretions and secretions beyond that which would occur in a typical pork production unit. Hand washing and donning clean outerwear did not prevent E coli transmission. However, showering and donning clean outerwear did prevent transmission