388 research outputs found

    Lignocellulose Conversion via Catalytic Transformations Yields Methoxyterephthalic Acid Directly from Sawdust

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    Poly(ethylene terephthalate) polyester represents the most common class of thermoplastic polymers widely used in the textile, bottling, and packaging industries. Terephthalic acid and ethylene glycol, both of petrochemical origin, are polymerized to yield the polyester. However, an earlier report suggests that polymerization of methoxyterephthalic acid with ethylene glycol provides a methoxy-polyester with similar properties. Currently, there are no established biobased synthetic routes toward the methoxyterephthalic acid monomer. Here, we show a viable route to the dicarboxylic acid from various tree species involving three catalytic steps. We demonstrate that sawdust can be converted to valuable aryl nitrile intermediates through hydrogenolysis, followed by an efficient fluorosulfation–catalytic cyanation sequence (>90%) and then converted to methoxyterephthalic acid by hydrolysis and oxidation. A preliminary polymerization result indicates a methoxy-polyester with acceptable thermal properties

    Radial Velocity Studies of Close Binary Stars. IX

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    Radial-velocity measurements and sine-curve fits to the orbital velocity variations are presented for the eighth set of ten close binary systems: AB And, V402 Aur, V445 Cep, V2082 Cyg, BX Dra, V918 Her, V502 Oph, V1363 Ori, KP Peg, V335 Peg. Half of the systems (V445 Cep, V2082 Cyg, V918 Her, V1363 Ori, V335 Peg) were discovered photometrically by the Hipparcos mission and all systems are double-lined (SB2) contact binaries. The broadening function method permitted improvement of the orbital elements for AB And and V502 Oph. The other systems have been observed for radial velocity variations for the first time; in this group are five bright (V<7.5) binaries: V445 Cep, V2082 Cyg, V918 Her, KP Peg and V335 Peg. Several of the studied systems are prime candidates for combined light and radial-velocity synthesis solutions.Comment: 17+ pages, 2 tables, 4 figure

    When assessment defines the content—understanding goals in between teachers and policy

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    © 2020 The Authors. The Curriculum Journal published by John Wiley & Sons Ltd on behalf of British Educational Research Association.Education policy development internationally reflect a widespread expansion of learning outcome orientation in policy, curricula and assessment. In this paper, teachers’ perceptions about their work are explored, as goals and assessment play a more prominent role driven by the introduction of a learning outcomes‐oriented system. This is investigated through interviews of Norwegian teachers and extensive policy analysis of Norwegian policy documents. The findings indicate that the teachers are finding ways to negotiate and adjust to the language in the policies investigated in this study. Furthermore, the findings show that the teachers have developed their professional language according to the policies. The teachers referred to their self‐made criteria and goal sheets as central tools in explicating what is to be learned. In many ways, the tools for assessment, thus determine the content of education as well as what is valued in the educational system.publishedVersio

    A methodology based on profitability criteria for defining the partial defection of customers in non-contractual settings

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    The defection or churn of customers represents an important concern for any company and a central matter of interest in customer base analysis. An additional complication arises in non-contractual settings, where the characteristics that should be observed to saying that a customer has totally or partially defected are not clearly defined. As a matter of fact, different definitions of the churn situation could be used in this context. Focusing on non-contractual settings, in this paper we propose a methodology for evaluating the short-time economic effects that using a certain definition of churn would have on a company. With this aim, we have defined two efficiency measures for the economic results of a marketing campaign implemented against churn, and these measures have been computed using a set of definitions of partial defection. Our methodology finds that definition maximizing both efficiency measures and moreover, the monetary amount that the company should invest per customer in the campaign for achieving the optimal solution. This has been modelled as a multiobjective optimization problem that we solved using compromise programming. Numerical results using real data from a Spanish retailing company are presented and discussed in order to show the performance and validity of our proposal.Clemente Císcar, M.; San Matías Izquierdo, S.; Giner Bosch, V. (2014). A methodology based on profitability criteria for defining the partial defection of customers in non-contractual settings. European Journal of Operational Research. 239(1):276-285. doi:10.1016/j.ejor.2014.04.029S276285239

    Развитие бизнес-процессов статистического управления качеством на Юргинском машзаводе

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    Micro-structured and thus functionalized surfaces offer high potentials for new approaches in processing techniques and product design. However, for mass production purposes quite a few challenges regarding the manufacturing of these surfaces have to be overcome. For the fast and economic production of large quantities of structured polymer films the extrusion embossing process is suitable. For embossing microstructures there are special requirements on temperature control because of the double function of the embossing roll. On the one hand the roll is used as an embossing roll with a high surface temperature to improve the embossing accuracy. On the other hand it is used as a cooling roll with a low surface temperature. Only by using variothermal heating systems these contradictory demands on the temperature control can be met. In order to achieve a high quality of the produced micro-structured films an integrative analysis and optimization of the entire process chain is required. This includes the manufacturing of suitable embossing rolls, the development of coating systems and the adaption of the extrusion process. This paper deals with the entire process chain for functionalized, super hydrophobic plastic parts with contact angles up to 165°. Therefore, conelike surface structures, mimicking the structure of lotus leaves, are replicated. Functionalized parts are produced in the injection molding as well as in the extrusion process; however, this paper focuses on the process chain of the extrusion process
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