The use of the palladium-catalyzed glycosylation for the synthesis of C- and O-linked glycosylated natural products

The carbohydrate portions of natural products play a crucial role in their pharmacological properties. These properties can vary from improved water solubility, improved membrane transport properties, improved tissue targeting, as well as improved target binding. Herein we describe our efforts to use de novo synthesis to help elucidate the various roles carbohydrates play in biologically active glycosylated natural products.;The O\u27Doherty group has developed a method that uses asymmetric synthesis for the de novo synthesis of carbohydrates. In contrast to traditional carbohydrate methods, this de novo approach builds the desired functionality and stereochemistry within each sugar. This methodology relies on a highly diastereoselective palladium(0)-catalyzed glycosylation reaction to control the stereochemistry at the anomeric center and post-glycosylation transformation to introduce the corresponding functionality in the sugar moiety.;This de novo approach was first used in a highly enantio- and diastereoselective synthesis of Vineomycin C and PI-080. The trisaccharide was made up of three rare sugars, an alpha-L-aculose, an alpha-L-rhodinose and a beta-D-olivose. The key transformations include: the palladium-catalyzed glycosylation, Myers\u27 reductive rearrangement, diastereoselective dihydroxylation, and regioselective Mitsunobu inversion. Material from this synthetic effort was used in several biological studies, such as 60-cell line cytotoxicity screens and apoptosis/necrosis mechanism of cell death studies. Significant apoptotic antitumor activity was found for this trisaccharide, which has implication for Vineomycin C and PI-080\u27s structure-activity relationship. To further elucidate the structural activity relationship for this trissacharide, we also prepared the enantiomeric D/D/L-trisaccharide, which is made up of alpha-D-aculose, alpha-D-rhodinose and beta-L-olivose sugars.;To further study the structure activity relationship of these C-aryl glycoside natural products, an effort was undertaken to develop a selective method for the installation of a beta-C-aryl glycoside bond to an intact di- and tri-sacchardes. This began with a de novo synthesis of the disaccharide portion of two new C-aryl glycoside natural products, SCH-47554 and SCH-47555. Unfortunately, despite the exhaustive screening of Lewis acid, no method was found for the formation of the desired beta- C-aryl glycoside bond that did not occur with hydrolysis of the di- and tri-saccharide glycosidic bonds.;In the final chapter, an effort was described that was aimed at the synthesis of hydroxyl-substituted analogues of two biologically important natural products for further glycosylation. The two natural products that were chosen for these studies were the poly-aromatic alkaloids ellipticine and camptothecin. This effort was aimed at trying to improve the water solubility/membrane transport properties of these anticancer natural products. While the efforts to prepare the required hydroxy-substituted aza-ellipticin failed, a glycosylated camptothecin was prepared. Unfortunately, the acid sestivity of the glycosylated camptothecin limits its use in biological studies

Full Glowworm Swarm Optimization Algorithm for Whole-Set Orders Scheduling in Single Machine

By analyzing the characteristics of whole-set orders problem and combining the theory of glowworm swarm optimization, a new glowworm swarm optimization algorithm for scheduling is proposed. A new hybrid-encoding schema combining with two-dimensional encoding and random-key encoding is given. In order to enhance the capability of optimal searching and speed up the convergence rate, the dynamical changed step strategy is integrated into this algorithm. Furthermore, experimental results prove its feasibility and efficiency

The Management Thinking Under the Phenomenon of Plagiarism in Chinese Net Literature

The Thirteenth Five-Year Plan period is an important period for China to become a powerful intellectual property country from a big intellectual property country. As an important part of intellectual property strategy, cultural innovation has attracted wide attention. For the most popular literary form at present, net literature drives the export of Chinese traditional culture and innovative culture. The case of "The Princess Wei yang" has aroused widespread concern in academic circles. How to define plagiarism and how to protect the rights of the authors has become a hot topic at present. This paper starts with the plagiaristic problem behind the adaptation of net literature, analyzes the negative impact of plagiarism on the creative willingness of the people and the national cultural innovation through questionnaires, and provides some effective suggestions for the problems of plagiarism which are difficult to define and safeguard legal rights. Keywords: net literature， plagiarism，adaptation，intellectual property rights，managemen

Adaptive networking control method and application of 5G vehicle networking node

at present, with the development of information technology, 5G network has been born, which also makes the Internet of things and the Internet based on the network develop rapidly. In this context, vehicular ad hoc network technology has attracted much attention. This technology has promoted the development of intelligent transportation from the research, birth and application in practice, so that intelligent transportation has been supported at the technical level, and its intelligent system has been optimized. In addition, vehicular ad hoc network technology plays a key role and value in road rescue, driverless and remote dispatching management. Therefore, this paper not only strengthens the greedy traffi c aware routing, but also optimizes the problems existing in its operation, and puts forward improved methods for the reference of the industry

Management and Maintenance of University Multimedia Voice Classroom

As an important part of teaching infrastructure, the management and maintenance of university multimedia Voice classroom has a direct impact on the conduct of university teaching

Optimization of sensitivity and noise in piezoresistive cantilevers

In this article, the sensitivity and the noise of piezoresistive cantilevers were systematically investigated with respect to the piezoresistor geometry, the piezoresistive materials, the doping dose, the annealing temperature, and the operating biased voltage. With the noise optimization results, dimension optimized array cantilevers were designed and fabricated by using single-crystal silicon, low-pressure chemical-vapor deposition (LPCVD) amorphous silicon and microcrystalline silicon as piezoresistive layers. Measurement results have shown that the smallest Hooge factor (alpha) was 3.2x10(-6), the biggest gauge factors was 95, and the minimum detectable deflection (MDD) at 6 V and 200 Hz-measurement bandwidth was 0.3 nm for a single-crystal silicon cantilever. Of the two LPCVD silicon piezoresistive cantilevers, amorphous silicon piezoresistors had relatively lower 1/f noise. The MDD for a LPCVD silicon cantilever at a 200 Hz-measurement bandwidth was 0.4 nm. For all kinds of piezoresistive cantilevers, the 1/f noises were decreased by 35%-50% and the gauge factors were decreased by 60-70% if the doping dose were increased by ten times. The annealing at 1050 degreesC for 30 min decreased 1/f noise by about 65% compared with the 950 degreesC for 10 min treatments. The cantilevers with a relatively higher-doping dose gave smaller MDD even though the gauge factors of them were decreased by nearly a factor of 1.8. The higher-biased voltages had no great improvements on the MDD due to the 1/f noise dominance. (C) 2002 American Institute of Physics.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000178987200111&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, AppliedSCI(E)EI97ARTICLE106296-63019

Automaticity in processing spatial-numerical associations: Evidence from a perceptual orientation judgment task of Arabic digits in frames.

Human adults are faster to respond to small/large numerals with their left/right hand when they judge the parity of numerals, which is known as the SNARC (spatial-numerical association of response codes) effect. It has been proposed that the size of the SNARC effect depends on response latencies. The current study introduced a perceptual orientation task, where participants were asked to judge the orientation of a digit or a frame surrounding the digit. The present study first confirmed the SNARC effect with native Chinese speakers (Experiment 1) using a parity task, and then examined whether the emergence and size of the SNARC effect depended on the response latencies (Experiments 2, 3, and 4) using a perceptual orientation judgment task. Our results suggested that (a) the automatic processing of response-related numerical-spatial information occurred with Chinese-speaking participants in the parity task; (b) the SNARC effect was also found when the task did not require semantic access; and (c) the size of the effect depended on the processing speed of the task-relevant dimension. Finally, we proposed an underlying mechanism to explain the SNARC effect in the perceptual orientation judgment task

A Generalization of Roth's Theorem in Function Fields

Copyright © 2012 The University of MichiganFor n ∈ N = {1, 2, ...}, let D3([1, n]) denote the maximal cardinality of an integer subset of [1, n] containing no nontrivial 3-term arithmetic progression. In a fundamental paper [9], Roth proved that D3([1, n]) n/log log n. His result was later improved by Heath-Brown [4] and Szemerédi [11] to D3([1, n]) n/(log n)α for some small positive constant α > 0 (α = 1/20 in [11]). By introducing the notion of Bohr sets, Bourgain [2; 3] further improved this bound and showed that D3([1, n]) n(log log n)2 /(log n)2/3Research partially supported by an NSERC Discovery Grant