Identifizierung der Natur aktiver Chromkatalysatoren in der Tetramerisierung von Ethen mittels in situ Spektroskopie

Die 1-Octen-Selektivität ist stark abhängig von der Natur des Präkusors, des Aktivators und des Liganden. Für die Katalysatorentwicklung sind genaue Informationen über die Bildung der tatsächlich aktiven Komplexe und deren Einfluss auf die katalytische Leistung erforderlich. Ziel ist es, die Wirkung von verschiedenen AlR3-Aktivatoren, Liganden und unterschiedlichen Präkursoren auf die Natur der katalytisch aktiven Cr-Spezies zu analysieren mit Hilfe einer maßgeschneiderten Kombination spektroskopischer In-situ-Methoden.The 1-octene selectivity is strongly dependent on the nature of the precursor, the activator and the ligand. The catalyst development requires precise information about the formation of the actually active complexes and their influence on the catalytic performance. The aim is to analyze the effect of various AlR3 activators, ligands and different precursors on the nature of the catalytically active Cr species with the help of a tailored combination of spectroscopic in situ methods

‘Jones hybrid’ hickory: a case study in Carya curation

‘Jones Hybrid’ hickory is an accession in the National Collection of Genetic Resources for Pecans and Hickories for which information about origin, identity and characteristics is very incomplete. Phenotypic and genetic profiles, when examined in the context of historic literature, provide evidence that the accession in question is ‘Siers’ a cultivar of Carya × laneyi (an interspecific hybrid between C. ovata and C. cordiformis). The accession has traits that make it interesting in the pecan breeding program, with potential for both rootstock and scion development. The tall, slender tree form of ‘Jones Hybrid’ is a trait that could be valuable in commercial pecan cultivars, allowing increased tree densities and reducing the need for expensive hedging operations. Tree size reduction is a goal to be pursued in scion selection and rootstock development, with each goal requiring assessment of reproductive potential of the accession

Co-Oligomers of Renewable and "Inert" 2-MeTHF and Propylene Oxide for Use in Bio-Based Adhesives

Commercial polyether polyols are usually obtained by the ring-opening polymerization of epoxides or tetrahydrofuran. 2-Methyl-tetrahydrofuran (2-MeTHF) could be an alternative bio-based building block for the synthesis of these polyols. Although 2-MeTHF cannot be polymerized, we did achieve the copolymerization of 2-MeTHF with propylene oxide (PO) using Lewis and Brønsted acids as catalysts and water or diols as initiators. The resulting polyether polyols have a molecular weight range, which allows their use as components for adhesives. The molar content of 2-MeTHF in the oligomers can be up to 48%. A 1:1 copolymer of 2-MeTHF and PO is produced when stoichiometric amounts of BF3·OEt2 are used. Here, the monomeric units in the chains alternate, but also cyclic or other nondiol products are formed that are detrimental to its further use in adhesives. Linear dihydroxyl-terminated polyether chains were formed when the heteropolyacid H3PW12O40·24H2O was used as a catalyst and a diol as an initiator. The formation of cyclic products can be drastically reduced when the accumulation of propylene oxide during the reaction is avoided. 1H NMR experiments indicate that the step of 2-MeTHF incorporation is the alkylation of 2-MeTHF by protonated PO. It was shown that the 2-MeTHF/PO copolymer had increased tensile strength compared to polypropylene glycol in a two-component adhesive formulation

Wild Plant Genetic Resources in North America: An Overview

North America, including Canada, Mexico, and the United States, is rich in plant species used by humans in both ancient and modern times. A select number of these have become globally important domesticated crops, including maize, beans, cotton, and sunflower. Many other native and also naturalized species have potential for use, either directly or as genetic resources for breeding agricultural crops. However, despite increasing recognition of their potential value, deficiencies in information, conservation, and access to the diversity in these plants hinder their further use. This chapter provides an overview of the agriculturally relevant wild plant resources of North America, with focus on wild relatives of globally important major crops, as well as the wild cousins of regionally and locally important domesticates. The chapter concludes by providing an overview of strategies for conserving wild plant genetic resources, including the international regulatory frameworks affecting policies to various degrees in Canada, Mexico, and the United States

The effect of dikegulac on shuck dehiscence and subsequent bud break in pecan trees Carya Illinoensis (Wang) K. Koch.

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Bibliography: leaves 57-61.Not availabl

A follow-up comparison of the attitudes of teachers who either did or did not participate in a Human Relations Institute

The thesis uses data provided by the Research Center at Houston Baptist College to compare the attitudes of a group of teachers (IP) who participated in Human Relations Institutes with the attitudes of a random sample of teachers (RS) from the same schools who did not participate in the Institutes. The first hypothesis is that the difference between the means of the white IP and the white RS will be greater than the difference between the means of the black IP and the black RS. The second hypothesis is that the difference between the means of the IP and RS will be greater on the attitude scale "Attitudes to Segregation," than on the experience scale "Previous Behavior Patterns with People of the Opposite Race." The third hypothesis is used to test the assumption that the IP and the RS are parallel groups. It is hypothesized that the attitude pattern created by stratifying the IP by age, sex, and marital status will be similar to the attitude pattern of the RS stratified by age, sex, and marital status. Subjects for this study consist of an experimental group of institute participants and a random group. There were 203 teachers who were IP subjects and 262 RS subjects whc were teachers drawn at random from the same schools as the IP subjects. From the total of both IP and RS subjects, 350 usable questionnaires were obtained. Raw score data profiles were tabulated for the two groups and analyzed statistically by computer. When testing for significance of difference between the IP and RS, the Z-test was used. When testing for significance of difference for variables within the IP, or within the RS, the t-test for significance of difference between two groups was used. The first hypothesis is confirmed at a high level of confidence by the data. There is significantly more difference between the white IP and the white RS than between the black IP and the black RS. The second hypothesis is partially confirmed by the data on black subjects. The data on the white subjects showed no difference in the response to an experience scale and an attitude scale. The results indicate that the black IP and the black RS are parallel groups and that the IP is insignificantly different from the RS due to the experience of human relations training. The white IP and the white RS are not parallel and the difference between the white IP and the white RS cannot be accredited to human relations training on the basis of this data. It is concluded that there is a wide range of attitude among white teachers concerning members of the black race, and that those who volunteer for human relations training tend to be those with the most favorable attitudes.Sociology, Department o

Radiology Case Reports Volume I, Issue 4, 2006 Dissociation of a Bipolar Prosthesis after Right Hip

We report the case of an 84-year-old woman with a dissociated bipolar component of her right hip hemiarthroplasty. Dissociation of components is a rare but increasingly recognized consequence of modular componentry. Radiologists should be aware of the distinction between dislocation of a prosthesis and dissociation of its bipolar components, and be able to describe these complications accurately in their interpretations. Case Report We report the case of an 84-year-old woman who fell, resulting in a fracture of her right femoral neck. This fracture was treated with placement of a bipolar hemiarthroplasty. Two weeks later, a routine post-operative radiograph demonstrated an abnormal appearance of her arthroplasty, despite no history of hip pain, leg numbness, or weakness. Initial right hip radiographs demonstrated dissociation of the components of the bipolar hemiarthroplasty, with inferomedial displacement of the acetabular cup component, and with the prosthetic femoral head abutting the roof of the acetabulum (Figure 1). There was no evidence of fracture or loosening of the femoral component of the prosthesis. The patient underwent successful conversion to total hip replacement and had an uneventful postoperative course. Discussion Although interpositional hip arthroplasty was first performed in the 1800's (1), it did not become commonplace, Citation: Grauke LJ, Richardson ML. Dissociation of a bipolar prosthesis after right hip hemiarthroplasty. Radiology Case Reports. [Online] 2006;1:55. Copyright: © Luke J. Grauke. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs 2.5 License, which permits reproduction and distribution, provided the original work is properly cited. Commercial use and derivative works are not permitted. Abbreviations: THA, total hip arthroplasty Luke J. Grauke (Email