Quantum Drag Forces on a Sphere Moving Through a Rarefied Gas

As an application of quantum fluid mechanics, we consider the drag force exerted on a sphere by an ultra-dilute gas. Quantum mechanical diffraction scattering theory enters in that regime wherein the mean free path of a molecule in the gas is large compared with the sphere radius. The drag force is computed in a model specified by the ``sticking fraction'' of events in which a gaseous molecule is adsorbed by the spherical surface. Classical inelastic scattering theory is shown to be inadequate for physically reasonable sticking fraction values. The quantum mechanical scattering drag force is exhibited theoretically and compared with experimental data.Comment: 5 pages no figure

A survey of combustible metals, thermites, and intermetallics for pyrotechnic applications

Thermite mixtures, intermetallic reactants, and metal fuels have long been used in pyrotechnics. Advantages include high energy density, impact insensitivity, high combustion temperature, and a wide range of gas production. They generally exhibit high temperature stability and possess insensitive ignition properties. This paper reviews the applications, benefits, and characteristics of thermite mixtures, intermetallic reactants, and metal fuels. 50 refs, tables

Origins and genetic legacy of prehistoric dogs

Dogs were the first domestic animal, but little is known about their population history and to what extent it was linked to humans. We sequenced 27 ancient dog genomes and found that all dogs share a common ancestry distinct from present-day wolves, with limited gene flow from wolves since domestication but substantial dog-to-wolf gene flow. By 11,000 years ago, at least five major ancestry lineages had diversified, demonstrating a deep genetic history of dogs during the Paleolithic. Coanalysis with human genomes reveals aspects of dog population history that mirror humans, including Levant-related ancestry in Africa and early agricultural Europe. Other aspects differ, including the impacts of steppe pastoralist expansions in West and East Eurasia and a near-complete turnover of Neolithic European dog ancestry

Bio-hybridization of nanobactericides with cellulose films for effective treatment against members of ESKAPE drug resistant pathogens

The rapid expansion of drug-resistant pathogens has created huge global impact and development of novel antimicrobial leads is one of the top priority studies in the current scenario. The present study aims to develop bio-hybridized nanocellulose films which comprise of phytogenic silver nanobactericides. The nanobactericides were synthesized by treating 1 mM silver nitrate with aqueous extract of Chamerion angustifolium which reduced the metal salt to produce polydispersed nanobactericides which were tested against the members of ESKAPE drug-resistant communities. The synthesized silver nanobactericides were subjected to characterization with UV–visible spectra which displayed maximum absorbance at 408 nm. The bio-molecular interaction of phyto-constituents to mediate synthesis and stabilization of nanobactericides was studied with Fourier-transform infrared spectroscopy (FTIR) which depicted functional groups associated with nanobactericides. The crystalline nature was studied with X-ray diffraction (XRD) which showed Bragg’s intensities at 2θ angle which denoted (111), (200), (220), and (311) planes. The morphological characteristics of silver nanobactericides were defined with transmission electron Microscopy (TEM) image which displayed polydispersity of silver nanobactericides with size ranging from 2 to 40 nm. The synthesized nanobactericides showed a significant activity against MRSA strain with 21 mm zone of inhibition. The minimal inhibitory concentration of silver nanobactericides to inhibit the growth of test pathogens was also determined which ranged between 0.625 and 1.25 μg/ml. The silver nanobactericides were bio-hybridized onto nanocellulose films produced by Komagataeibacter xylinus B-12068 culture strain. The films were dried to determine the mechanical properties which showed increased in Young’s modulus and tensile strength in comparison with control bacterial cellulose films. Overall, the results obtained in the present investigation are promising enough to report bactericidal activity of bio-hybridized nanobactericidal films against ESKAPE. These communities are reported to cause severe threats to all forms of lives irrespective to their habitats which can lead to huge economical crisis

Semi dwarf continental woolly mammoth from the East Siberian Sea coast, continental Russia

Bioarchaeolog

Intraspecific phylogenetic analysis of Siberian woolly mammoths using complete mitochondrial genomes

We report five new complete mitochondrial DNA (mtDNA) genomes of Siberian woolly mammoth (Mammuthus primigenius), sequenced with up to 73-fold coverage from DNA extracted from hair shaft material. Three of the sequences present the first complete mtDNA genomes of mammoth clade II. Analysis of these and 13 recently published mtDNA genomes demonstrates the existence of two apparently sympatric mtDNA clades that exhibit high interclade divergence. The analytical power afforded by the analysis of the complete mtDNA genomes reveals a surprisingly ancient coalescence age of the two clades, ≈1–2 million years, depending on the calibration technique. Furthermore, statistical analysis of the temporal distribution of the 14C ages of these and previously identified members of the two mammoth clades suggests that clade II went extinct before clade I. Modeling of protein structures failed to indicate any important functional difference between genomes belonging to the two clades, suggesting that the loss of clade II more likely is due to genetic drift than a selective sweep