139 research outputs found
(2R*,3R*,4aS*,6aR*,11aS*,11bS*)-Methyl 2-acetoxy-11b-hydroxy-3,7-dimethyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodecahydrophenanthro[3,2-b]furan-3-carboxylate
In the title compound, C22H30O6, the conformation of the molecule is dictated by an intramolecular C—H⋯O contact. The crystal structure is stabilized via intermolecular C—H⋯O, O—H⋯O and C—H⋯π contacts
Whole-genome sequencing for an enhanced understanding of genetic variation among South Africans
The Southern African Human Genome Programme is a national initiative that aspires to
unlock the unique genetic character of southern African populations for a better understanding
of human genetic diversity. In this pilot study the Southern African Human Genome
Programme characterizes the genomes of 24 individuals (8 Coloured and 16 black southeastern
Bantu-speakers) using deep whole-genome sequencing. A total of ~16 million unique
variants are identified. Despite the shallow time depth since divergence between the two
main southeastern Bantu-speaking groups (Nguni and Sotho-Tswana), principal component
analysis and structure analysis reveal significant (p < 10−6) differentiation, and FST analysis
identifies regions with high divergence. The Coloured individuals show evidence of varying
proportions of admixture with Khoesan, Bantu-speakers, Europeans, and populations from the
Indian sub-continent. Whole-genome sequencing data reveal extensive genomic diversity,
increasing our understanding of the complex and region-specific history of African populations
and highlighting its potential impact on biomedical research and genetic susceptibility to
disease
The intersection of archaeology, oral tradition and history in the South African interior.
The historical entanglement of indigenous and colonial societies in South
Africa created not only multiple points of social and cultural interaction, but
also a repository of interconnected material, oral and documentary records.
A multi-source, comparative approach across disciplinary boundaries is,
therefore, essential to achieve a full and seamless account of late precolonial and
early colonial African history. Oral tradition could serve as a bridge between
archaeology and text-based history, thereby enabling historically known
political lineages to be connected with the archaeological ruins of specific
precolonial African towns. Similarly, documentary sources on African societies
of the interior are often very limited in scope even deep into the nineteenth
century, as a result of which the complementary use of archaeological
methods and data becomes a methodological imperative. Three case studies
from the South African interior, Marothodi, Kaditshwene and Magoro Hill,
are presented to illustrate the explanatory potential of an interdisciplinary
approach to the study of the more recent African past
A reinvestigation of the ferrocene oxidation by iron(III) chloride in 2-butanone-ethanol
[[abstract]]The reaction of ferrocene with iron(III) chloride (4:3) in 2-butanone-ethanol-diethyl ether affords diferricenium μ-oxo-bis(trichloroferrate) with the anionic iron centres in the iron(III) oxidation state. The structure, determined by X-ray diffractometry, is corroborated by analytical and spectroscopic evidence[[notice]]補正完畢[[incitationindex]]SC
Conformation of pentaazamacrocyclics. 2. Determination of two disordered structures (15-ane N5)Cu(II) and (16-ane N5)Ni(II) using molecular mechanics
All is Number
Rational numbers, which correctly describe many recognizable patterns
in the physical world, are often seen to converge in the process to irrational limits
or even singularities. As a common example, atomic numbers are well known
as fundamental parameters in chemistry, but by demonstrating that the periodicity
of atomic matter is simulated by the convergence of rational fractions, from unity
to the golden ratio, the importance of limiting processes and irrational limits in
the modelling of chemical systems and of phenomena such as superconduction is
emphasized. Other limiting formulae feature in atomic spectral series, radioactive
decay, circular measure, absolute temperature, the speed of light, structure of the
solar system and gravitational collapse. In virtually all cases the convergence involves
the irrational golden ratio and the golden spiral, the essential properties of
which are briefly reviewed in summary of the arguments developed in this volume.
The suspicion that molecular shape should have a related number basis could not be
substantiated. Only in the double-helical base pairing of DNA could any correlation
between molecular structure and number theory be demonstrated. It is tempting to
conjecture that the ubiquitous appearance of irrational limits signals the inadequacy
of the R3 number system to provide a detailed account of the four-dimensional
world.http://www.springer.com/series/430hj201
Complexation with diol host compounds. Part 17. Structures and thermal analysis of 9,9′-dihydroxy-9,9′-bifluorene with ethanol, 1-butanol and pyridine
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