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101.
Sorption measurements are executed to study the sorption behavior of propylene in a semicrystalline polymer. Decreasing values for the Flory–Huggins interaction parameter with increasing temperature are obtained. Large deviations are found, especially at higher temperatures, compared to data from the literature. Propylene is polymerized in liquid and gaseous propylenes with Me2Si[Ind]2ZrCl2/MAO/SiO2 as the metallocene catalyst. Lower relative reaction rates are found in the gas phase compared to the experiments in the liquid phase. The activation energies from the experiments in both phases are on the same order of magnitude. However, the literature versus experimental sorption data has a large effect on the determined kinetic parameters. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1193–1206, 2001 相似文献
102.
G. H. Meier 《工业材料与腐蚀》1996,47(11):595-618
Research on the oxidation behavior of intermetallic compounds has been conducted in the U.S. for many years. However, until about ten years ago, this work focusses on the compounds which are important in Ni-base superalloys and their coatings: mainly Ni3Al and NiAl More recent work has been directed at systems which may be used in monolithic form or as the base for composites. Work has concentrated on three types of systems: Ni- and Fealuminides, refractory metal compounds, and titanium aluminides. Work on the Ni- and Fe-aluminides has concentrated mainly on adherence problems and some anomolous behavior. Work on the refractory metal compounds, particularly MoSi2 and NbAl3, has dealt with the problem of selectively oxidizing Al or Si from a refractory metal base and various intermediate-temperature forms of degradation, such as “pesting”. It has become increasingly more clear that, for a number of reasons, the titanium aluminides will be the first “new” metallic materials introduced into commercial high temperature applications (probably aircraft gas turbines and automobiles engines) in many years. As a result a very large amount of work is being done on the oxidation behaviour of these compounds. Initial work dealt with oxidation mechanisms at temperatures on the order of 1000°C. However, both oxidation and mechanical property considerations dictate that the alloys will not be used at temperatures much above 750°C. Therefore, current work is being focussed on oxidation mechanisms at lower temperature and on what may be the “Achilles heel” of these materials, environmental embrittlement. This paper summarizes the work being done in the U.S. and highlights work on what the author believes are the more important problems. 相似文献
103.
Dieter Grschl Axel Mayer Michael Schmidt Herbert Meier 《Advanced Synthesis \u0026amp; Catalysis》1995,337(1):379-384
Synthesis of Benzo[b]thioxanthenes Benzo[b]thioxanthenes, heterocyclic compounds related to tetracenes and tetracyclines can be obtained by the reaction of 2H-benzo[b]thiete ( 1 ) and 1,4-naphthoquinones ( 3a–g ). The primary cycloadducts 4a–g undergo an autoxidation process leading to the quinones 6a–g . The dihydroxy compound 4e shows an additional isomerization by a tetrafold H transfer ( 4e → 5e ′). Another preparative route to benzo[b]thioxanthenes makes use of the cycloadditon reaction of 1 and 1,4-epoxynaphthalenes ( 7a–d ). The primary adducts can be transformed to the title compounds by catalytic dehydration processes ( 8a–d → 9a-d ). An alternate regioselective opening of the oxygen bridge can be performed by the action of trimethyliodosilane ( 8a → 10a ). Methylation of 9a furnishes the sulfonium salt 14a which rearranges in a strongly alkaline medium to 16a ; in the presence of oxygen ketone 17a is generated. 相似文献
104.
在纺织品染色的不同工艺中,纱线染色是有着许多优点的标准工艺.纱线染色能同各种纺织工序结合起来,对纱线的适应性非常广,并能染出具有多功能性的筒子卷装.经济因素通常是最重要的,筒子染色由于其相对短的工艺流程,因此只需较低的成本.考虑到这种工艺对市场需求的响应速度快,纺织企业能从这个高灵活性的工艺中获利. 相似文献
105.
研究区位于新疆东天山觉罗塔格造山带吐哈盆地以南百灵山以北,多年来对于研究区古生代构造背景的认识受前人热议,存在争议。通过对研究区新发现基性岩体的岩石、地球化学特征与构造背景进行探讨,以期为大区域构造背景的研究提供一定的数据支持。主量元素研究表明,康南岩体具有高Mg、Fe,低Al的特征,说明研究区基性侵入岩为碱性岩石系列。微量元素测试结果表明具有同源演化的特征,Rb、Hf元素亏损较为严重。K、Ba、P、Sm富集明显,Tb、Nb、Ti表现为弱异常,在稀土元素球粒陨石标准化配分模式图中Eu的负异常不明显,表现为弱的正异常, Yb+Nb-Rb构造环境判别图解中样品落在“后碰撞”环境内,以上特征说明具有岛弧花岗岩的基本特征。岩性为深灰绿色弱蚀变细粒橄榄辉绿岩。 相似文献
106.
Leon Wehrhan Prof. Dr. Alexander Hillisch Dr. Stefan Mundt Dr. Adrian Tersteegen Dr. Katharina Meier 《ChemMedChem》2020,15(21):2010-2018
Target druggability assessment is an integral part of the early target characterization and selection process in pharmaceutical industry. Here, we investigate a set of five different serine proteases from the blood coagulation cascade. The aim of this study is twofold. Firstly, leveraging the wealth of available in-house high-throughput screening (HTS) data, we analyze HTS hit rates and discuss their predictive value for the development of small molecule (SMOL) candidates. Purely structure-activity relationship (SAR) based druggability ratings are compared with computational protein-structure based druggability assessments. Secondly, we evaluate the impact of using conformational ensembles from molecular dynamics (MD) simulations instead of single static crystal structures as basis for computational druggability assessments. Based on this study, we recommend incorporating molecular dynamics routinely into the early target characterization process, especially if only a single X-ray structure is available. 相似文献
107.
108.
The synergistic bactericidal effects of vitamin B1 (thiamine dilauryl sulfate) and the efficacy of commercial sanitizers for minimization of Bacillus cereus contamination in cooked rice were investigated. Sanitizer-treated rice exhibited a greater reduction than water-treated rice, while sanitizer-treated rice with Vitamin B1 produced an even greater reduction. The treatments for B. cereus in rice included (1) 100 ppm hydrogen peroxide with 500 ppm vitamin B1 ; (2) 200 ppm hydrogen peroxide with 100 ppm vitamin B1 ; (3) 400 ppm hydrogen peroxide; (4) 50 ppm chlorine with 500 ppm vitamin B1 ; (5) 60 ppm chlorine with 300 ppm vitamin B1 ; (6) 70 ppm chlorine with 100 ppm vitamin B1 ; (7) 80 ppm chlorine; and (8) 100,000 ppm ethanol with 500 vitamin B1. All treatments completely eliminated B. cereus in rice. The sensory properties of all sanitizer-treated cooked rice did not differ significantly from the same properties for water-treated cooked rice.
The prevalence of Bacillus cereus in rice and rice products has been documented and control of the growth of B. cereus in rice is an important consideration. The results obtained from this study can be of use to rice producers in the manufacture of safe products. Although chemical disinfectants can be used to reduce the amount of B. cereus in rice, vitamin B1 can also be used as an effective additive that reduces the amount of disinfectant use via a synergistic antimicrobial effect. The increasing use of chemical disinfectants for safety in the food industry can be reversed using our method. 相似文献
PRACTICAL APPLICATIONS
The prevalence of Bacillus cereus in rice and rice products has been documented and control of the growth of B. cereus in rice is an important consideration. The results obtained from this study can be of use to rice producers in the manufacture of safe products. Although chemical disinfectants can be used to reduce the amount of B. cereus in rice, vitamin B
109.
不采用二次辐照,将TL 分析法应用于辐照茶叶的定性鉴定。分离并收集茶叶中黏附的硅酸盐,采用热释光剂量仪测量获得硅酸盐的热释光发光曲线,比较未辐照与辐照不同剂量茶叶的热释光发光曲线的积分强度、峰值和峰值温度等特征参数。未辐照茶叶的热释光发光曲线的积分强度小于50、峰值小于0.4、峰值温度大于260℃;反之,辐照茶叶的热释光发光曲线的积分强度大于50000、峰值大于600、峰值温度位于160~190℃。TL 分析法能判别出茶叶的辐照与否,尤其对不能满足参比剂量辐照条件的样品很有帮助。 相似文献
110.
M. Vailati-Riboni G. Farina F. Batistel A. Heiser M.D. Mitchell M.A. Crookenden C.G. Walker J.K. Kay S. Meier J.R. Roche J.J. Loor 《Journal of dairy science》2017,100(3):2334-2350
The common practice of increasing dietary energy density during the close-up dry period (last ~3 wk prepartum) has been recently associated with a higher incidence of metabolic disorders after calving. Despite these reports, over-feeding of metabolizable energy (ME) during the far-off, nonlactating period is a common management policy aimed at achieving optimum calving body condition score (BCS) in pasture-based systems, as cows are generally thinner than total mixed ration cows at the end of lactation. Our hypothesis was that both far-off and close-up overfeeding influence the peripartum adipose tissue changes associated with energy balance and inflammatory state. Sixty mid-lactation, grazing dairy cows of mixed age and breed were randomly allocated to 1 of 2 groups that were managed through late lactation to achieve a low and high BCS (approximately 4.25 and 5.0 on a 10-point scale) at dry-off. The low BCS cows were then overfed ME to ensure that they achieved the same BCS as the higher BCS group by calving. Within each rate of BCS gain treatment, cows were offered 65, 90, or 120% of their pre-calving ME requirements for 3 wk pre-calving in a 2 × 3 factorial arrangement of treatments (i.e., 10 cows/treatment). Subcutaneous adipose tissue was collected via biopsy at ?1, 1, and 4 wk relative to parturition. Quantitative PCR was used to measure mRNA and microRNA expression of targets related to adipogenesis and inflammation. Cows overfed in the far-off period had increased expression of miR-143 and miR-378 prepartum (?1 wk) indicating greater adipogenesis, consistent with their rapid gain in BCS following dry-off. Furthermore, the lower postpartum expression of IL6, TNF, TLR4, TLR9, and miR-145, and a higher abundance of miR-99a indicated lower body fat mobilization in early lactation in the same group. In the close-up period, feeding either 65 or 120% of ME requirements caused changes in FASN, IL1B, IL6R, TLR9, and the microRNA miR-143, miR-155, and miR-378. Their respective expression patterns indicate a tentative negative-feedback mechanism in metabolically compromised, feed-restricted cows, and a possible immune-related stimulation of lipolysis in apparently static adipocytes in overfed cows. Data from cows fed 90% of ME requirements indicate the existence of a balance between lipolytic (inflammatory-related) and anti-lipolytic signals, to prime the mobilization machinery in light of imminent lactation. Overall, results indicate that far-off dry cow nutrition influences peripartum adipose tissue metabolism, with neither strategy negatively affecting the physiological adaptation to lactation. Furthermore, to ensure a favorable transition, cows should be subjected to a small feed restriction in the close-up period, irrespective of far-off nutritional management. 相似文献