Geochemical Fractionation of Trace Elements between Calcite and Dolomite Fractions Separated from Their Mixture in Some Egyptian Dolomitic Limestone Rocks

Abstract: The present work is an attempt to separate calcite and dolomite fractions from dolomitic limestone samples. Fifty recognized dolomitic limestone samples were selected from several localities to cover most types of the Egyptian dolomitic limestone varieties. A series of experiments was carried out to determine the best conditions for the dissolution of calcite only and hence the chemical separation of calcite from dolomite in the dolomitic limestone samples. Calcite and dolomite were quantitatively differentiated from dolomitic limestone rocks by a method based on the quantitative dissolution of calcite in pH 4 buffer solution. The remaining dolomite is then dissolved in 1 N-HCl. The trace elements (Fe, Mn, Cd, Co, Ni, Zn, Pb, Sr & Ba) concentrations in both calcite and dolomite fractions were determined to through light on their distribution. Fe, Mn and Ni show a similar distribution being present in great amount in dolomite fraction than calcite fraction. Sr and Ba also are present to a great extent in dolomite fraction than calcite fraction. Cd, Co, Zn and Pb show distinctly different behavior to that of other elements, they rarely exceed 20 ppm in both calcite and dolomite fraction

Correlating novel variable and conserved motifs in the Hemagglutinin protein with significant biological functions

<p>Abstract</p> <p>Background</p> <p>Variations in the influenza Hemagglutinin protein contributes to antigenic drift resulting in decreased efficiency of seasonal influenza vaccines and escape from host immune response. We performed an in silico study to determine characteristics of novel variable and conserved motifs in the Hemagglutinin protein from previously reported H3N2 strains isolated from Hong Kong from 1968–1999 to predict viral motifs involved in significant biological functions.</p> <p>Results</p> <p>14 MEME blocks were generated and comparative analysis of the MEME blocks identified blocks 1, 2, 3 and 7 to correlate with several biological functions. Analysis of the different Hemagglutinin sequences elucidated that the single block 7 has the highest frequency of amino acid substitution and the highest number of co-mutating pairs. MEME 2 showed intermediate variability and MEME 1 was the most conserved. Interestingly, MEME blocks 2 and 7 had the highest incidence of potential post-translational modifications sites including phosphorylation sites, ASN glycosylation motifs and N-myristylation sites. Similarly, these 2 blocks overlap with previously identified antigenic sites and receptor binding sites.</p> <p>Conclusion</p> <p>Our study identifies motifs in the Hemagglutinin protein with different amino acid substitution frequencies over a 31 years period, and derives relevant functional characteristics by correlation of these motifs with potential post-translational modifications sites, antigenic and receptor binding sites.</p

A systematic review of the safety of topical therapies for atopic dermatitis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75613/1/j.1365-2133.2006.07538.x.pd

A year of genomic surveillance reveals how the SARS-CoV-2 pandemic unfolded in Africa

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A year of genomic surveillance reveals how the SARS-CoV-2 pandemic unfolded in Africa.

The progression of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic in Africa has so far been heterogeneous, and the full impact is not yet well understood. In this study, we describe the genomic epidemiology using a dataset of 8746 genomes from 33 African countries and two overseas territories. We show that the epidemics in most countries were initiated by importations predominantly from Europe, which diminished after the early introduction of international travel restrictions. As the pandemic progressed, ongoing transmission in many countries and increasing mobility led to the emergence and spread within the continent of many variants of concern and interest, such as B.1.351, B.1.525, A.23.1, and C.1.1. Although distorted by low sampling numbers and blind spots, the findings highlight that Africa must not be left behind in the global pandemic response, otherwise it could become a source for new variants