(S)-(+)-γ-苄氧基甲基-γ-丁内酯的合成研究

以Ｌ 谷氨酸为原料,首先在－５～０℃条件下重氮化,随后常温内酯化,然后在对甲苯磺酸催化下于苯中回流进行酯化,用硼氢化钠在常温下还原,最后用氧化银作为碱发生常温威廉逊（Ｗｉｌｉａｍｓｏｎ）醚化反应,以３２３％的总产率合成了标题化合物。     

琥珀酸单薄荷酯合成工艺的研究

薄荷醇和琥珀酸酐在4-二甲氨基吡啶的催化作用下,以CHCl3为溶剂,合成凉味剂琥珀酸单薄荷酯。其最佳的反应条件为:薄荷醇与琥珀酸酐的摩尔比为1:1.5,反应时间24h,反应温度为50℃,催化剂与薄荷醇的摩尔比为0.128:1,产物纯度为99.70%,产率为92.50%。     

Headspace fingerprinting as an untargeted approach to compare novel and traditional processing technologies: A case-study on orange juice pasteurisation

As a rule, previous studies have generally addressed the comparison of novel and traditional processing technologies by a targeted approach, in the sense that only the impact on specific quality attributes is investigated. By contrast, this work focused on an untargeted strategy, in order to take into account unexpected and unintended effects of (novel) processing, and to possibly uncover unknown compounds resulting from alternative processing. The potential of headspace GC–MS fingerprinting was explored as a tool to compare the impact of thermal, high pressure (HP) and pulsed electric field (PEF) processing for mild pasteurisation of orange juice. This study demonstrated that when processing conditions are selected based on equivalent microbial safety, the impact of heat, HP and PEF pasteurisation on the volatile profile of orange juice can be considered comparable. During refrigerated storage, however, indirect impact differences were revealed, which were attributed to differences in degree of enzyme inactivation.     

Investigating the Molecular Mechanisms of Renal Hepcidin Induction and Protection upon Hemoglobin-Induced Acute Kidney Injury

Hemolysis is known to cause acute kidney injury (AKI). The iron regulatory hormone hepcidin, produced by renal distal tubules, is suggested to exert a renoprotective role during this pathology. We aimed to elucidate the molecular mechanisms of renal hepcidin synthesis and its protection against hemoglobin-induced AKI. In contrast to known hepatic hepcidin induction, incubation of mouse cortical collecting duct (mCCD_cl1) cells with IL-6 or LPS did not induce Hamp1 mRNA expression, whereas iron (FeS) and hemin significantly induced hepcidin synthesis (p < 0.05). Moreover, iron/heme-mediated hepcidin induction in mCCD_cl1 cells was caused by the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, as indicated by increased nuclear Nrf2 translocation and induced expression of Nrf2 downstream targets GCLM (p < 0.001), NQO1 (p < 0.001), and TXNRD1 (p < 0.005), which could be prevented by the known Nrf2 inhibitor trigonelline. Newly created inducible kidney-specific hepcidin KO mice demonstrated a significant reduction in renal Hamp1 mRNA expression. Phenylhydrazine (PHZ)-induced hemolysis caused renal iron loading and oxidative stress in both wildtype (Wt) and KO mice. PHZ treatment in Wt induced inflammatory markers (IL-6, TNFα) but not Hamp1. However, since PHZ treatment also significantly reduced systemic hepcidin levels in both Wt and KO mice (both p < 0.001), a dissection between the roles of systemic and renal hepcidin could not be made. Combined, the results of our study indicate that there are kidney-specific mechanisms in hepcidin regulation, as indicated by the dominant role of iron and not inflammation as an inducer of renal hepcidin, but also emphasize the complex interplay of various iron regulatory mechanisms during AKI on a local and systemic level.     

High-Temperature Phase Relations in Selected MnO-CrOx-Containing Systems

Phase relations in the pseudobinary MnO-CrO _x system were studied by the reaction of the individual oxides in the temperature range 1400°-1750°C under a reducing atmosphere with a CO:CO₂ volume ratio of 4.8, yielding oxygen partial pressures in the range 10^-9.98-10^-6.97 atm. In the pseudoternary MnO-CrO _x -containing systems that constitute the pseudoquaternary MnO-CrO _x -CaO-SiO₂ system, phase relations were determined only at 1500°C under an oxygen partial pressure of 10^−8.99 atm. Characteristic of these MnO-CrO _x -containing systems was the dominance of the (Mn,Cr)₃O₄ spinel phase.     

Psychic Distance,Innovation, and Firm Performance

Previous research suggests that internationalization improves a firm’s ability to innovate, but the effect of internationalizing into specific target markets or destinations on the innovation ability of firms has not been fully investigated. This study examined whether the psychic distance between target market and home market affects firms’ propensity to innovate. The starting assumption was that perception of a high degree of differences and subsequent environmental uncertainty when expanding into psychically distant markets triggers strategies for interacting and integrating with the market environment. These include producing and adopting innovations to processes and products and to organizational strategy, structure, and administrative procedures to cope with the new environment and overcome uncertainties. These innovations and the associated competitive advantages can improve firm performance. Hypotheses regarding the relationships between psychic distance, innovation, and firm performance were tested here by structural equation modeling using data from 186 export ventures into 23 international markets by Swedish companies. The results indicate that the link between psychic distance and firm performance is mediated by innovation.     

Influence of Isothermal Treatment on MnS and Hot Ductility in Low Carbon,Low Mn Steels

Hot ductility tests were used to determine the hot-cracking susceptibility of two low-carbon, low Mn/S ratio steels and compared with a higher-carbon plain C-Mn steel and a low C, high Mn/S ratio steel. Specimens were solution treated at 1623 K (1350 °C) or in situ melted before cooling at 100 K/min to various testing temperatures and strained at 7.5 × 10^?4 s^?1, using a Gleeble 3500 Thermomechanical Simulator. The low C, low Mn/S steels showed embrittlement from 1073 K to 1323 K (800 °C to 1050 °C) because of precipitation of MnS at the austenite grain boundaries combined with large grain size. Isothermal holding for 10 minutes at 1273 K (1000 °C) coarsened the MnS leading to significant improvement in hot ductility. The higher-carbon plain C-Mn steel only displayed a narrow trough less than the Ae₃ temperature because of intergranular failure occurring along thin films of ferrite at prior austenite boundaries. The low C, high Mn/S steel had improved ductility for solution treatment conditions over that of in situ melt conditions because of the grain-refining influence of Ti. The higher Mn/S ratio steel yielded significantly better ductility than the low Mn/S ratio steels. The low hot ductility of the two low Mn/S grades was in disagreement with commercial findings where no cracking susceptibility has been reported. This discrepancy was due to the oversimplification of the thermal history of the hot ductility testing in comparison with commercial production leading to a marked difference in precipitation behavior, whereas laboratory conditions promoted fine sulfide precipitation along the austenite grain boundaries and hence, low ductility.     

Thermodynamic properties of solid Pt-Mn, Pt-Cr, and Pt-Mn-Cr alloys at 1500 °C

Equations for the activity coefficients of manganese and chromium in platinum at 1500 °C were determined from activity-composition relations in the Pt-Mn, Pt-Cr, and Pt-Mn-Cr systems. This was done by equilibrating platinum wire with, respectively, MnO, Cr₂O₃, and an equimolar mixture of Cr₂O₃ and (Mn, Cr)₃O₄, under oxygen partial pressures that ranged from 10⁻⁶⁵ to 10⁻¹⁰⁰ atm. It was found that equations for the activity coefficients can be represented by Darken’s quadratic formalism. The experimental data confirmed that the Pt-Mn, Pt-Cr, and Pt-Mn-Cr alloys studied show strong negative deviations from ideality, as is expected from the respective phase diagrams.     

Teaching Turkish-Dutch kindergartners Dutch vocabulary with a social robot: Does the robot's use of Turkish translations benefit children's Dutch vocabulary learning?

Providing first language (L1) translations in L2 vocabulary interventions may be beneficial for L2 vocabulary learning. However, in linguistically diverse L2 classrooms, teachers cannot provide L1 translations to all children. Social robots do offer such opportunities, as they can be programmed to speak any combination of languages. This study investigates whether providing L1 translations in a robot-assisted L2 vocabulary training facilitates children's learning. Participants were Turkish-Dutch kindergartners (n = 67) who were taught six Dutch (L2) words for which they knew the L1 (Turkish), but not the L2 Dutch form. Half of these words were taught by a Turkish-Dutch bilingual robot, alongside their Turkish translations; the other half by a monolingual Dutch robot. Children also completed Dutch and Turkish receptive vocabulary tests. Results of generalized linear regression models indicated better performance in the Dutch-only condition than in the Turkish-Dutch condition. Children with well-developed Turkish and Dutch vocabulary knowledge outperformed children with less well-developed vocabulary knowledge. The majority of children preferred working with the bilingual robot, but children's preference did not affect word learning. Thus, contrary to our prediction, we found no evidence for a facilitating effect of providing L1 translations through a robot on bilingual children's L2 word learning.     

The effects of different types of product information on the consumer product evaluation for fresh cod in real life settings

The effects of different types of product information on consumer product evaluation were examined in real life settings. Cod fillets were presented to 1440 consumers drawn from the Dutch TasteNet consumer panel for assessment in their own households. The product was presented accompanied by product information included in the package labelling. A control product, labelled simply as cod, was included. Consumers reported their evaluation of the product for overall and analytic sensory attributes. It was found that information about product type, price, freshness and the advantages of fish farming could influence product evaluation. Cod labelled as wild, highly priced or recently caught was judged more favourably than the unlabelled product. Information on the advantages of farming had a negative effect on product evaluation that interacted with price so as to minimise the positive effect of the latter. Interaction of the information provided with product perception in a realistic situation demonstrated that farmed fish was associated with less favourable product characteristics.