Diatoms Associated with Bryophyte Communities Growing at Extreme Depths in Lake Michigan

Diatom assemblages on limestone cobbles collected from 42.7 m depth in the mid-lake high region of Lake Michigan are characterized by low total abundance and low diversity. The flora present contains three associations. A large allochthonous component, comprised of planktonic species and very low numbers of benthic species usually found in shallow water is present. A limited number of dominant taxa appear to be particularly associated with deep habitats in oligotrophic lakes. Other species, usually reported from terrestrial habitats, appear to be associated with the bryophyte Fissidens fontanis which is present in the collections

Notes on Iowa Diatoms. VI I. Rare and Little Known Diatoms from lowa

This paper reports the occurrence and known The Treatment of a Cesium Ore by Sulfur Chloride and Chlorine1distribution of 44 rare taxa of diatoms in Iowa. Illustrations of the entities cited are furnished

Homology Models of the Papain-Like Protease PLpro from Coronavirus 2019-nCoV

The December 2019 outbreak of pneumonia in Wuhan, Hubei Province of China was rapidly linked to a novel coronavirus 2019-nCoV. The rapid spread and severity of the virus has led the World Health Organization to declare it a Public Health Emergency of International Concern. We recently described the first homology models of the main 3CL protease from 2019-nCoV, and now present models of the other viral protease, the papain-like protease or PLpro. Whilst the overall viral genome is most closely associated with bat coronaviruses, no bat PLpro crystal structures are known. Wuhan 2019-nCoV PLpro is most closely related to a bat coronavirus PLpro (97% identity), then SARS (80 %) and MERS (29%) and the most promising models presented here are prepared from SARS crystal structure templates

The Evolution of the DePauw Woman

Widespread participation by women in higher education is something that many people in my generation take for granted. While women now outnumber men on the DePauw campus by about a 55 to 45 ratio, that is a remarkably recent phenomenon. Nearly 150 years ago four fearless women came to Greencastle to pave the way for thousands of women who followed by the 1990s. We do not know, without some research, what our predecessors have had to go through in order for us to be here at DePauw today. Not only have the numbers of women on campus exploded over the past century and one-half, but these DePauw women have become more adventurous with majors and professions, marriage is less of a priority, and more women are attempting additional degrees

Introduction - Special Issue in Honor of Professor John. D. Dodd on the Occasion of His Retirement

This issue of the Proceedings is dedicated to Professor John D. Dodd on the occasion of his 65th birthday. During his long and distinguished career at Iowa State University, Professor Dodd has exemplified the very best qualities of teaching and academic research in the botanical sciences. He finds genuine and unfailing fascination in his chosen field and one senses that his fondest desire is to elevate all of his students to his own perspective so that they might share the same rewards he finds in discovery of facts and comprehension of principles. Although few can match his intellectual capacity and catholic interests, he has provided many beginning students with a unique insight into the fundamentals of biology and inspired many of the graduate students fortunate enough to work with him to pursue fundamental research, particularly in unconventional or neglected areas

The chemistry of vinyllead triacetates

This thesis is concerned with the investigations of the reactions of vinyllead tricarboxylates, derived from vinylstannanes and divinylmercury compounds, and their applications to organic synthesis. The work is discussed in three sections: Section 1: VINYLLEAD TRICARBOXYLATES AS A SOURCE OF VINYL CATIONS The reaction of a vinylstannane or divinylmercury compound with lead tetraacetate (or other tetracarboxylates), generally performed in chloroform solution, gives rise to a vinyllead triacetate. These species are usually unstable compounds that decompose via either a vinyl cation mechanism, or a /3-elimination (Reactions A and B). Compelling evidence for vinyl cation formation was obtained in a number of cases, in which rearrangement across the double bond occurred (e.g. Reaction A). By using suitably substituted vinylstannanes, it was possible to generate primary vinyl cations, species which are thought not to be formed in solvolysis reactions. In two cases, the vinyl cations formed underwent intramolecular aromatic electrophilic substitution (e.g. Reaction C). It was shown in a series of experiments that the mechanism was not of a carbene nature, as species arising from carbene insertion into carbon-carbon double bonds were not observed (e.g. Reaction D). Capture of the cationic intermediate by neighbouring methoxyl groups was also observed (Reaction E). SECTION 2: IMPROVEMENTS IN THE a-VINYLATION REACTION OF /3-DICARBONYL COMPOUNDS The vinyllead tricarboxylates mentioned above, have been used in the past* as vinylating reagents for /3-dicarbonyl compounds (Reaction F). The use of tributylvinylstannanes and divinylmercury compounds as the precursors of the lead reagent, had serious limitations, both in the ease of purification of the products and in the production of "wasted" vinylic residues. The use of trimethylvinylstannanes has now been shown to produce not only easier workup procedures, but also in general higher yields of the vinylated products than was previously attainable. It was also found that lead tetrabenzoate was a superior reagent in this reaction, producing faster exchange times and better yields. Lead tetrapivalate was found to be better than lead teraacetate in some cases, but inferior to lead tetrabenzoate. * Moloney, M.G., and Pinhey, J.T., J. Chem. Soc. Perkin Trans. 1, 1988, 10, 2847. SECTION 3: JH AND °C NMR STUDIES OF VINYLLEAD TRICARBOXYLATES By the use of high resolution n.m.r. spectroscopy, it was possible to characterise a large number of vinyl-lead tricarboxylates by means of the 207Pb satellites about the vinylic protons in the *H n.m.r. spectra of these compounds. These 207Pb-H coupling costants were very large (690-1660 Hz) and found to decrease in the series: J 207Pb,Htram > J 207Pb,Hgem > J 207Pb,Hcis In a few cases it was also possible to observe 207Pb-C coupling constants in the n.m.r. spectra of these compounds. It was also found that the lead compounds were identical, whether derived from the tributylstannanes or trimethylstannanes, or from the mercury compounds

Homology Models of Coronavirus 2019-nCoV 3CLpro Protease

A regional outbreak of pneumonia in Wuhan, Hubei Province of China in late 2019 was associated with a novel coronavirus. Rapid release of genomic data for the isolated virus enabled the construction of first-generation homology models of the new CoV 3CLpro cysteine protease. Whilst the overall viral genome was most closely associated with bat coronaviruses, the main protease is most closely related (96% identity) to SARS CoV protease