4,127 research outputs found
Determination of the absolute configurations at stereogenic centers in the presence of axial chirality
No full textCephalochromin, a homodimeric naphthpyranone natural product, contains both axial chirality due to the hindered rotation along the biaryl axis and central chirality due to the C-2, C-20 stereogenic centers of the fused pyranone ring. For determining the absolute configurations (ACs) of central chirality elements, different chiroptical spectroscopic methods, namely vibrational circular dichroism (VCD), electronic circular dichroism (ECD), and optical rotation (OR), have been used. From these experimental data, in conjunction with corresponding quantum chemical predictions at B3LYP/6-311G* level, it is found that the ECD spectra of cephalochromin are dominated by its axial chirality and are not suitable to distinguish the (aS,2S,20S) and (aS,2R,20R) diastereomers and hence to determine the ACs of the central chirality elements. OR signs also did not distinguish the (aS,2S,20S) and (aS,2R,20R) diastereomers. On other hand, VCD spectrum of cephalochromin exhibited separate spectral features attributable to axial chirality and stereogenic centers, thereby allowing the determination of both types of chirality elements. This is the first investigation demonstrating that, because of vibrations specific to the studied stereogenic centers, VCD spectroscopy can be used to simultaneously determine the ACs of axial and central chirality elements whenever other chiroptical methods (ECD and OR) fail to report on them
Electronic CD of Benzene and other Aromatic Chromophores for Determination of Absolute Configuration
No full textAssignment of the Absolute Configuration of Natural Products by Means of Solid-State Electronic Circular Dichroism and Quantum Mechanical Calculations
No full textRecent developments in chiral separations by supercritical fluid chromatography
No full textThe increasing interest for obtaining pure, single enantiomers of chiral organic compounds has greatly expanded the progress of new synthetic procedures, especially in the field of chiral drugs, agrochemicals, flavors, and natural products. A parallel trend has been observed in the development of stereoselective separation methods for the precise and accurate measurements of the enantiomeric purity of chiral compounds. The advent of chiral stationary phases for gas or liquid chromatographic applications in the last three decades changed the approach to determine enantiomeric purity on the analytical scale and to obtain sizeable amounts of pure enantiomers by preparative resolutions. In recent years, continuous efforts have been placed on faster analytical methods and on environment-friendly processes. Chromatographic processes using supercritical fluids, especially carbon dioxide, combine both aspects with success because of the extremely favorable properties of the eluents in terms of physicochemical
parameters and of impact on the environment. An overview of the recent achievements in the field of supercritical fluid chromatography using packed column with chiral stationary phases will be given, with an emphasis on very recent studies on high-efficiency, ultrafast chiral separations
The FM and PL Libraries Documentation
No full textBuilding complex SPMD code in an ecient and portable way is nowadays a challenge, especially when there is no uniformity of tools and libraries across platforms. The Fast Messages (FM) and the Portability Library (PL) where both designed to provide the basis of an abstract enough framework for C, so that problems can be coded and ported to any supported platform with no more than a few changes in the makeles and a recompilation. The FM library provides a message passing communications library built around the Berkeley Active Messages library. The PL library provides the primitives for host to node communication for problem initialization and results collection, as well as other miscellaneous and potentially non-portable primitives. This technical report contains the documentation for both libraries.Technical report LCSR-TR-25
Increasing science, technology, engineering, and mathematics skills using Project Lead the Way
No full textIncludes bibliographical references
Introduction to Urban Science: Evidence and Theory of Cities as Complex Systems
No full textLuís Bettencourt provides a timely, comprehensive, and rigorous treatment of urban space, by contributing to the
advancement of knowledge in the field of urban science. The author develops a valuable scientific guide for researchers,
policymakers, practitioners, and students interested in understanding cities as complex systems. Today, more than half of
world's population lives in urban areas, and, according to theWorld Bank data, by 2045, urban citizens will increase up to
6 billion. Cities of different sizes will play a pivotal role in the postpandemic recovery and, most importantly, they will
make the green transition of our economies and societies really work in coming years. Therefore, understanding “how
each city and every one of its people is the result of the aggregation of many choices, accidents, and influences from
their compounded joint history” (p. xxi) becomes crucial to manage present and future local and global challenges
MultiEmo: Multilingual, Multilevel, Multidomain Sentiment Analysis Corpus of Consumer Reviews
No full textMultiEmo, a new benchmark data set for the multilingual sentiment analysis task including 11 languages. The collection contains consumer reviews from four domains: medicine, hotels, products and university. The original reviews in Polish contained 8,216 documents consisting of 57,466 sentences. The reviews were manually annotated with sentiment at the level of the whole document and at the level of a sentence (3 annotators per element). We achieved a high Positive Specific Agreement value of 0.91 for texts and 0.88 for sentences. The collection was then translated automatically into English, Chinese, Italian, Japanese, Russian, German, Spanish, French, Dutch and Portuguese. MultiEmo is publicly available under a Creative Commons Attribution 4.0 International Licence.
More information: https://github.com/CLARIN-PL/multiemo
Citation:
@inproceedings{kocon2021multiemo,
title={Multiemo: Multilingual, multilevel, multidomain sentiment analysis corpus of consumer reviews},
author={Koco{\'n}, Jan and Mi{\l}kowski, Piotr and Kanclerz, Kamil},
booktitle={International Conference on Computational Science},
pages={297--312},
year={2021},
organization={Springer}
The chain-level intersection product for PL pseudomanifolds revisited
No full textAbstract We generalize the PL intersection product for chains on PL manifolds and for intersection chains on PL stratified pseudomanifolds to products of locally finite chains on non-compact spaces that are natural with respect to restriction to open sets. This is necessary to sheafify the intersection product, an essential step in proving duality between the Goresky-MacPherson intersection homology product and the intersection cohomology cup product pairing recently defined by the author and McClure. We also provide a correction to the Goresky-MacPherson proof of a version of Poincaré duality on pseudomanifolds that is used in the construction of the intersection product
Prodromus Entomology : Natural History Of Lepidopterous Insects Of New South Wales ; Collected, Engraved, And Faithfully Painted After Nature / By John William Lewin, A.L.S. Of Paramatta, New South Wales. Published From The Hand Of His Brother Thomas Lewin ...
No full textPRODROMUS ENTOMOLOGY : NATURAL HISTORY OF LEPIDOPTEROUS INSECTS OF NEW SOUTH WALES ; COLLECTED, ENGRAVED, AND FAITHFULLY PAINTED AFTER NATURE / BY JOHN WILLIAM LEWIN, A.L.S. OF PARAMATTA, NEW SOUTH WALES. PUBLISHED FROM THE HAND OF HIS BROTHER THOMAS LEWIN ...
Prodromus Entomology : Natural History Of Lepidopterous Insects Of New South Wales ; Collected, Engraved, And Faithfully Painted After Nature / By John William Lewin, A.L.S. Of Paramatta, New South Wales. Published From The Hand Of His Brother Thomas Lewin ... (1)
Cover (1)
Frontispiz / Titelseite (10)
Widmung (11)
Preface (12)
Phalaenoides Glycinae. Pl. 1. (14)
Sphinx Ardenia. Pl. 2. (16)
Sphinx Oldenlandiae. Pl. 3. (17)
Bombyx Vulnerans. Pl. 4. (19)
Bombyx Nasuta. Pl. 5. (20)
Bombyx Lewinae. Pl. 6. (22)
Bombyx Exposita. Pl. 7. (23)
Bombyx Tristis. Pl. 8. (25)
Bombyx Banksiae. Pl. 9. (26)
Cryptophasa Irrorata. Pl. 10. (28)
Cryptophasa Albacosta. Pl. 11. (29)
Cryptophasa Rubescens. Pl. 12. (31)
Cryptophasa Pultenae. Pl. 13. (32)
Cryptophasa Strigata. Pl. 14. (34)
Lithosa Replana. Pl. 15. (35)
Hepialus Ligniveren. Pl. 16. (37)
Tortrix Australana. Pl. 17. (38)
Tinea Cossuna. Pl. 18. (40)
Publication Prices (41
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