Iminophosphorane-mediated regioselective umpolung alkylation reaction of α-iminoesters

2021 ◽  
Author(s):  
Yasushi Yoshida ◽  
Mayu Kukita ◽  
Kazuki Omori ◽  
Takashi Mino ◽  
Masami Sakamoto
Keyword(s):  
Asymmetric Reactions ◽  
Alkylation Reaction ◽  
Chiral Amines ◽  
Efficient Manner

Umpolung reactions of imines, especially the asymmetric reactions, have been extensively studied as they provide access to important chiral amines in an efficient manner. The reactions studied range from simple...

An Image Reconstruction System Applied to High Voltage Microscopy

1975 ◽  
Vol 33 ◽  
pp. 292-293
Author(s):  
D. E. Johnson
Keyword(s):  
High Voltage ◽  
Prior Information ◽  
Block Diagram ◽  
Three Dimensional ◽  
Real Space ◽  
Two Dimensional ◽  
Efficient Manner ◽  
Fourier Methods ◽  
Tilt Series ◽  
Methods Of Reconstruction

Increased specimen penetration; the principle advantage of high voltage microscopy, is accompanied by an increased need to utilize information on three dimensional specimen structure available in the form of two dimensional projections (i.e. micrographs). We are engaged in a program to develop methods which allow the maximum use of information contained in a through tilt series of micrographs to determine three dimensional speciman structure.In general, we are dealing with structures lacking in symmetry and with projections available from only a limited span of angles (±60°). For these reasons, we must make maximum use of any prior information available about the specimen. To do this in the most efficient manner, we have concentrated on iterative, real space methods rather than Fourier methods of reconstruction. The particular iterative algorithm we have developed is given in detail in ref. 3. A block diagram of the complete reconstruction system is shown in fig. 1.

Systems view of integrated water quality monitoring within the requirements of the new national water policy in South Africa

1998 ◽  
Vol 38 (11) ◽  
pp. 141-148 ◽  
Author(s):  
P. Marjanovic ◽  
M. Miloradov
Keyword(s):  
South Africa ◽  
Water Quality ◽  
Water Policy ◽  
Systems Approach ◽  
Water Quality Management ◽  
Water Quality Monitoring ◽  
Point Sources ◽  
Quality Monitoring ◽  
Efficient Manner ◽  
National Water

The new National water policy will change the way water quality is managed in South Africa. The paper considers the water policy and the repercussions it will have for water quality monitoring in South Africa. Using the systems approach the paper discusses an integrated water quality monitoring system for ambient water quality and point and non point sources of aquatic pollution. The proposed methodology makes possible continuos assessment of water quality in an efficient manner so as to support water quality management in South Africa.

N-Substituted Amides as Chiral Ligands for Catalytic Asymmetric Reactions

2002 ◽  
Vol 6 (10) ◽  
pp. 865-890 ◽  
Author(s):  
Ji Zhang ◽  
Hai-Bing Zhou ◽  
Ru-Gang Xie
Keyword(s):  
Asymmetric Reactions ◽  
Chiral Ligands ◽  
Catalytic Asymmetric ◽  
Catalytic Asymmetric Reactions

D-Glucosamine-derived Chiral Catalysts For Asymmetric Reactions

2013 ◽  
Vol 17 (14) ◽  
pp. 1507-1524 ◽  
Author(s):  
Chao Shen ◽  
Peng-Fei Zhang
Keyword(s):  
Asymmetric Reactions ◽  
Chiral Catalysts

Applications of Quantitative Structure-Activity Relationships (QSAR) based Virtual Screening in Drug Design: A Review

2020 ◽  
Vol 20 (14) ◽  
pp. 1375-1388 ◽  
Author(s):  
Patnala Ganga Raju Achary
Keyword(s):  
Machine Learning ◽  
Drug Discovery ◽  
Virtual Screening ◽  
Model Building ◽  
Chemical Space ◽  
Qsar Model ◽  
Quantitative Structure ◽  
Efficient Manner ◽  
Qsar Analysis ◽  
Structure Activity

The scientists, and the researchers around the globe generate tremendous amount of information everyday; for instance, so far more than 74 million molecules are registered in Chemical Abstract Services. According to a recent study, at present we have around 1060 molecules, which are classified as new drug-like molecules. The library of such molecules is now considered as ‘dark chemical space’ or ‘dark chemistry.’ Now, in order to explore such hidden molecules scientifically, a good number of live and updated databases (protein, cell, tissues, structure, drugs, etc.) are available today. The synchronization of the three different sciences: ‘genomics’, proteomics and ‘in-silico simulation’ will revolutionize the process of drug discovery. The screening of a sizable number of drugs like molecules is a challenge and it must be treated in an efficient manner. Virtual screening (VS) is an important computational tool in the drug discovery process; however, experimental verification of the drugs also equally important for the drug development process. The quantitative structure-activity relationship (QSAR) analysis is one of the machine learning technique, which is extensively used in VS techniques. QSAR is well-known for its high and fast throughput screening with a satisfactory hit rate. The QSAR model building involves (i) chemo-genomics data collection from a database or literature (ii) Calculation of right descriptors from molecular representation (iii) establishing a relationship (model) between biological activity and the selected descriptors (iv) application of QSAR model to predict the biological property for the molecules. All the hits obtained by the VS technique needs to be experimentally verified. The present mini-review highlights: the web-based machine learning tools, the role of QSAR in VS techniques, successful applications of QSAR based VS leading to the drug discovery and advantages and challenges of QSAR.

Performance Analysis of RNC Clustering Protocol in Wireless Sensor Network

2019 ◽  
Vol 10 ◽  
Author(s):  
Piyush Rawat ◽  
Siddhartha Chauhan
Keyword(s):  
Energy Consumption ◽  
Network Performance ◽  
Energy Levels ◽  
Cluster Head ◽  
Base Station ◽  
Sensor Nodes ◽  
Wireless Sensor ◽  
Threshold Function ◽  
Efficient Manner ◽  
Clustering Protocol

Background and Objective: The functionalities of wireless sensor networks (WSN) are growing in various areas, so to handle the energy consumption of network in an efficient manner is a challenging task. The sensor nodes in the WSN are equipped with limited battery power, so there is a need to utilize the sensor power in an efficient way. The clustering of nodes in the network is one of the ways to handle the limited energy of nodes to enhance the lifetime of the network for its longer working without failure. Methods: The proposed approach is based on forming a cluster of various sensor nodes and then selecting a sensor as cluster head (CH). The heterogeneous sensor nodes are used in the proposed approach in which sensors are provided with different energy levels. The selection of an efficient node as CH can help in enhancing the network lifetime. The threshold function and random function are used for selecting the cluster head among various sensors for selecting the efficient node as CH. Various performance parameters such as network lifespan, packets transferred to the base station (BS) and energy consumption are used to perform the comparison between the proposed technique and previous approaches. Results and Discussion: To validate the working of the proposed technique the simulation is performed in MATLAB simulator. The proposed approach has enhanced the lifetime of the network as compared to the existing approaches. The proposed algorithm is compared with various existing techniques to measure its performance and effectiveness. The sensor nodes are randomly deployed in a 100m*100m area. Conclusion: The simulation results showed that the proposed technique has enhanced the lifespan of the network by utilizing the node’s energy in an efficient manner and reduced the consumption of energy for better network performance.

Asymmetric reactions. X. Configuration on asymmetric nitrogen and phosphorus

1966 ◽  
Vol 31 (4) ◽  
pp. 1910-1913 ◽  
Author(s):  
O. Červinka ◽  
O. Kříž
Keyword(s):  
Asymmetric Reactions ◽  
Nitrogen And Phosphorus ◽  
Asymmetric Nitrogen

Asymmetric reactions. XXXIX. Circular dichroism of some alkylphenylacetic acids

1971 ◽  
Vol 36 (4) ◽  
pp. 1687-1689 ◽  
Author(s):  
O. Červinka ◽  
L. Hub ◽  
G. Snatzke
Keyword(s):  
Circular Dichroism ◽  
Asymmetric Reactions ◽  
Circular Dichroïsm

Asymmetric reactions. XXVIII. Absolute configuration of some necic acids

1968 ◽  
Vol 33 (9) ◽  
pp. 2933-2940 ◽  
Author(s):  
O. Červinka ◽  
L. Hub
Keyword(s):  
Absolute Configuration ◽  
Asymmetric Reactions

Asymmetric reactions. XV. Pyrolysis of cyclooctanol and cyclodecanol esters of S-(+)-hydratropic acid

1967 ◽  
Vol 32 (6) ◽  
pp. 2381-2382 ◽  
Author(s):  
O. Červinka ◽  
J. Budilová ◽  
M. Daněček
Keyword(s):  
Asymmetric Reactions
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