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Sengupta, S.,Lee, W.S. Academic Press 2014 BIOSYSTEMS ENGINEERING Vol.117 No.-
Yield mapping for tree crops by mechanical harvesting requires automatic detection and counting of fruits in tree canopy. However, partial occlusion, shape irregularity, varying illumination, multiple sizes and similarity with the background make fruit identification a very difficult task to achieve. Therefore, immature green citrus-fruit detection within a green canopy is a challenging task due to all the above-mentioned problems. A novel algorithmic technique was used to detect immature green citrus fruit in tree canopy under natural outdoor conditions. Shape analysis and texture classification were two integral parts of the algorithm. Shape analysis was conducted to detect as many fruits as possible. Texture classification by a support vector machine (SVM), Canny edge detection combined with a graph-based connected component algorithm and Hough line detection, were used to remove false positives. Next, keypoints were detected using a scale invariant feature transform (SIFT) algorithm and to further remove false positives. A majority voting scheme was implemented to make the algorithm more robust. The algorithm was able to accurately detect and count 80.4% of citrus fruit in a validation set of images acquired from a citrus grove under natural outdoor conditions. The algorithm could be further improved to provide growers early yield estimation so that growers can manage grove more efficiently on a site-specific basis to increase yield and profit.
A Concise Synthesis of Mupirocin H Using a Cross‐Metathesis‐Based Strategy
Sengupta, Sandip,Sim, Taebo WILEY‐VCH Verlag 2014 EUROPEAN JOURNAL OF ORGANIC CHEMISTRY Vol.2014 No.23
<P><B>Abstract</B></P><P>A highly efficient (10.1 % overall yield) and convergent (longest linear sequence of 16 steps) synthesis of mupirocin H has been achieved, starting from commercially available (+)‐(<I>R</I>)‐Roche ester. The route relies on an efficient Grubbs cross‐metathesis reaction to generate a key, late‐stage <I>E</I>‐olefin intermediate, and a cobalt‐catalysed diastereoselective Reformatsky reaction to produce a β‐hydroxy ester that serves as a late‐stage intermediate.</P>
Highly stereoselective synthesis of mupirocin H
Sengupta, S.,Kim, H.J.,Cho, K.S.,Song, W.Y.,Sim, T. Pergamon Press 2017 Tetrahedron Vol.73 No.8
A highly diastereoselective and efficient convergent synthesis of mupirocin H starting from (+)-®-Roche ester was achieved. Grubbs cross metathesis was employed as the key step in the pathway to generate an important E-olefin intermediate. Other processes utilized in the route include a Pd-catalysed stereoselective substitution reaction of a cis epoxide, Sharpless epoxidation followed by Red-Al promoted epoxide ring opening, and Seebach methylation and a TEMPO/BAIB mediated oxidation-lactonization sequence. Finally, we observed that mupirocin H inhibits SbnE, a synthetase required for staphyloferrin B biosynthesis.
Empirical Tests of New Growth Theory : Openness and Growth
Sengupta, Jati K. 세종대학교 국제경제연구소 1994 Journal of Economic Integration Vol.9 No.3
New growth theory has stressed the role of export externality and increasing returns to scale in promoting sustained growth. This paper discusses these sources of economic growth in Asian NICs(newly industrializing countries) in recent times by applying some modern econometric tests based on cointegration and other methods. Countries such as Japan, Korea and Taiwan are considered as examples for empirical applications of the broad tenets of the new growth theory.
Structural Revision of Baulamycin A and Structure–Activity Relationships of Baulamycin A Derivatives
Sengupta, Sandip,Bae, Munhyung,Oh, Dong-Chan,Dash, Uttam,Kim, Hak Joong,Song, Woon Young,Shin, Injae,Sim, Taebo American Chemical Society 2017 Journal of organic chemistry Vol.82 No.24
<P>Total synthesis of the proposed structure of baulamycin A was performed. The spectral properties of the synthetic compound differ from those reported for the natural product. On the basis of comprehensive NMR study, we proposed two other possible structures for natural baulamycin A. Total syntheses of these two substances were performed, which enabled assignment of the correct structure of baulamycin A. Key features of the convergent and fully stereocontrolled route include Evans Aldol and Brown allylation reactions to construct the left fragment, a prolinol amide-derived alkylation/desymmetrization to install the methyl-substituted centers in the right fragment, and finally, a Carreira alkynylation to join both fragments. In addition, we have determined the inhibitory activities of novel baulamycin A derivatives against the enzyme SbnE. This SAR study provides useful insight into the design of novel SbnE inhibitors that overcome the drug resistance of pathogens, which cause life-threatening infections.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/joceah/2017/joceah.2017.82.issue-24/acs.joc.7b01719/production/images/medium/jo-2017-017198_0020.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jo7b01719'>ACS Electronic Supporting Info</A></P>
Arp 65 interaction debris: massive H I displacement and star formation
Sengupta, C.,Scott, T. C.,Paudel, S.,Saikia, D. J.,Dwarakanath, K. S.,Sohn, B. W. EDP Sciences 2015 Astronomy and astrophysics Vol.584 No.-
<P>Context. Pre?merger tidal interactions between pairs of galaxies are known to induce significant changes in the morphologies and kinematics of the stellar and interstellar medium components. Large amounts of gas and stars are often found to be disturbed or displaced as tidal debris. This debris then evolves, sometimes forming stars and occasionally forming tidal dwarf galaxies. Here we present results from our HI study of Arp 65, an interacting pair hosting extended HI tidal debris. Aims. In an effort to understand the evolution of tidal debris produced by interacting pairs of galaxies, including in situ star and tidal dwarf galaxy formation, we are mapping HI in a sample of interacting galaxy pairs. The Arp 65 pair is the latest member of this sample to be mapped. Methods. Our resolved HI 21 cm line survey is being carried out using the Giant Metrewave Radio Telescope. We used our HI survey data as well as available SDSS optical, Spitzer infra-red and GALEX UV data to study the evolution of the tidal debris and the correlation of HI with the star-forming regions within it. Results. In Arp 65 we see a high impact pre?merger tidal interaction involving a pair of massive galaxies (NGC90 and NGC93) that have a stellar mass ratio of ~1:3. The interaction, which probably occurred ~1.02.5 × 10<SUP>8</SUP> yr ago, appears to have displaced a large fraction of the HI in NGC90 (including the highest column density HI) beyond its optical disk. We also find extended on-going star formation in the outer disk of NGC90. In the major star-forming regions, we find the HI column densities to be ~4.7 × 10<SUP>20</SUP> cm<SUP>−2</SUP> or lower. But no signature of star formation was found in the highest column density HI debris SE of NGC90. This indicates conditions within the highest density HI debris remain hostile to star formation and it reaffirms that high HI column densities may be a necessary but not sufficient criterion for star formation.</P>