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111.
Summary: A rigorous process model has been developed which describes a closed-loop recycling system for PET beverage bottles. The reaction / mass transport model is aimed at the dominant quality parameters such as intrinsic viscosity, concentration of acetaldehyde, concentration of carboxylic end-groups, and concentration of vinyl end-groups, respectively. The model covers the main process steps being preform production (injection moulding), drying, solid-state polycondensation, and melt filtration. The simulation reveals that after a single recycling loop all the relevant quality parameters achieve the specification, if certain temperatures, residence times, and surface areas for degassing are provided during the recycling process. Another simulation showed the evolution of quality parameters in PET being subjected to an “infinite” number of recycling loops in a closed system. In this case, the concentration of acetaldehyde and vinyl end-groups decreases with the number of recycling loops, which is a desired effect. On the other hand, the concentration of carboxylic end-groups increases with every completed recycling loop. Higher concentrations of carboxylic end-groups make the polymer more susceptible to hydrolysis and increase the SSP process time needed to achieve the specified intrinsic viscosity for carbonated soft drink bottles. To overcome this problem, the recycled PET has to be blended with a certain amount of virgin PET in industrial processes. 相似文献
112.
Hanife biolu Baak Temur lker Ün 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,74(2):329-335
A number of new spiro–ansa spermidine derivative cyclotriphosphazenes (2–10) is synthesized in order to provide insight into the reaction mechanism for nucleophilic substitution. The structures of the compounds were determined by elemental analysis, mass (MS), 1H, 19F (for 9) and 31P NMR spectroscopies. Compounds (2–8) and 9, 10 can be formed by a proton abstraction–chloride elimination and both the and reaction mechanisms, respectively. 相似文献
113.
In this paper, a novel robust watermarking technique using particle swarm optimization and k-nearest neighbor algorithm is introduced to protect the intellectual property rights of color images in the spatial domain. In the embedding process, the color image is separated into non-overlapping blocks and each bit of the binary watermark is embedded into the individual blocks. Then, in order to extract the embedded watermark, features are obtained from watermark embedded blocks using the symmetric cross-shape kernel. These features are used to generate two centroids belonging to each binary (1 and 0) value of the watermark implementing particle swarm optimization. Subsequently, the embedded watermark is extracted by evaluating these centroids utilizing k-nearest neighbor algorithm. According to the test results, embedded watermark is extracted successfully even if the watermarked image is exposed to various image processing attacks. 相似文献
114.
P. Grabar Weiland E. di Benedetto A. D. Marenzi H. K. Barrenscheen Luise Messiner L. T. Poulsson A. Leulier L. Velluz H. Griffon J. L. Steenkamp K. L. Maljarow J. Weber W. Krane J. M. Kolthoff A. Martini G. Denigès P. W. Seltwood A. Benedetti-Pichler F. Schneider L. Moser J. Singer Fr. L. Hahn H. v. Euler H. Hellström D. Runehjelm H. Lundegårdh Joshimatsu F. Eichholtz Richard Berg W. Wölker E. Skopp F. P. Mazza A. Rossi B. Groák Léon Velluz R. Deschaseaux A. Astruc M. Mousseron Th. Kuttner H. R. Cohen J. H. Roe B. S. Kahn F. Rogozinski R. Strebinger 《Analytical and bioanalytical chemistry》1932,87(1-2):39-44
115.
In order to investigate deterioration processes on the famous 2000-yr-old Chinese Terracotta warriors, deformation measurements were performed with TV-holography. The aim of the investigations is to estimate the suitability of several conservation agents and procedures, which are developed to preserve the extremely endangered paint layers of the figures. Due to the occurrence of small-scale deformation areas the field of view had to be reduced. A microscopic system was constructed and typical object deformations due to shrinkage and swelling are presented. To investigate the individual layers of the multilayered objects a short-coherent superluminescence diode instead of a laser diode is used in a further modification. By changing the path length of one of the interfering beams it is possible to select a region limited in depth where deformations are measured even if it is located below the surface. Results on an artificial test object and on original terracotta fragments demonstrate the capabilities of this new short-coherence TV-holography system. 相似文献
116.
Shu-Cherng Fang Soonyi Wu Ş. İlker Birbil 《Computational Optimization and Applications》2007,37(1):67-81
We study a variational inequality problem whose domain is defined by infinitely many linear inequalities. A discretization
method and an analytic center based inexact cutting plane method are proposed. Under proper assumptions, the convergence results
for both methods are given. We also provide numerical examples to illustrate the proposed methods.
The work of S. Wu was partially supported by the National Science Council, Taiwan, ROC (Grant No. 19731001). S.-C. Fang’s
research has been supported by the US Army Research Office (Grant No. W911NF-04-D-0003) and National Science Foundation (Grant
No. DMI-0553310). 相似文献
117.
Back Cover: Total Synthesis of 7‐ and 8‐Oxygenated Pyrano[3,2‐a]carbazole and Pyrano[2,3‐a]carbazole Alkaloids via Boronic Acid‐Catalyzed Annulation of the Pyran Ring (Chem. Eur. J. 28/2014) 下载免费PDF全文
118.
Total Synthesis of 7‐ and 8‐Oxygenated Pyrano[3,2‐a]carbazole and Pyrano[2,3‐a]carbazole Alkaloids via Boronic Acid‐Catalyzed Annulation of the Pyran Ring 下载免费PDF全文
Dr. Konstanze K. Julich‐Gruner Dr. Olga Kataeva Dr. Arndt W. Schmidt Prof. Dr. Hans‐Joachim Knölker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(28):8536-8540
The boronic acid‐catalyzed annulation of citral opens up a short route to oxygenated cyclized monoterpenoid pyranocarbazole alkaloids. Thus, murrayamine‐D is available in only three steps and 55% overall yield from the corresponding carbazole precursor. 相似文献
119.
Timo Völker Dr. Felix Dempwolff Prof. Dr. Peter L. Graumann Prof. Dr. Eric Meggers 《Angewandte Chemie (International ed. in English)》2014,53(39):10536-10540
The catalysis of bioorthogonal transformations inside living organisms is a formidable challenge—yet bears great potential for future applications in chemical biology and medicinal chemistry. We herein disclose highly active organometallic ruthenium complexes for bioorthogonal catalysis under biologically relevant conditions and inside living cells. The catalysts uncage allyl carbamate protected amines with unprecedented high turnover numbers of up to 270 cycles in the presence of water, air, and millimolar concentrations of thiols. By live‐cell imaging of HeLa cells and with the aid of a caged fluorescent probe we could reveal a rapid development of intense fluorescence within the cellular cytoplasm and therefore support the proposed bioorthogonality of the catalysts. In addition, to illustrate the manifold applications of bioorthogonal catalysis, we developed a method for catalytic in‐cell activation of a caged anticancer drug, which efficiently induced apoptosis in HeLa cells. 相似文献
120.
We present a thorough analysis of the economic production quantity model with shortages under a general inventory cost rate function and piecewise linear concave production costs. Consequently, an effective solution procedure, particularly useful for an approximation scheme, is proposed. A computational study is appended to illustrate the performance of the proposed solution procedure. 相似文献