How to define a diatom genus? Notes on the creation and recognition of taxa, and a call for revisionary studies of diatoms

© by John Patrick Kociolek. This work is an open access paper licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License. (CC BY-NC-ND 4.0). The attached file is the published version of the article

Part I Synthesis and study of cyclic sulfamates Part II Investigation of endocyclic nucleophilic substitution at tetracoordinate sulfur(VI)

Part I. 5-Nitro-N-(p-toluenesulfonyl)-1,2,3-benzoxathiazole-2,2-dioxide was synthesized and reacted with various nucleophiles. Nitrogen nucleophiles attacked the exocyclic sulfur atom resulting in cleavage of the tosyl group. This is due in part to the acidity of the parent benzoxathiazole ring. A series of substituted N-H-1,2,3-benzoxathiazole-2,2-dioxides were synthesized and their pK\sb{\rm a} values were determined. An ab initio study was also undertaken on a simple sulfamate model in order to determine the origin of the increased acidity of the cyclic sulfamates, compared to their acyclic analogues. It was determined that the increased acidity was directly affected by the conformation of the neighboring heteroatoms. This is primarily due to heteratom-sulfur delocalization. Investigations of the role of d-orbitals on the stabilization of the system were inconclusive. An ab initio study of the increased acidity of the cyclic compounds compared to their acyclic analogues of sulfamide, methyl sulfonamide and vinyl sulfonamide was undertaken. The sulfamide and methyl sulfonamide models gave results consistent with experimental results, the former showing an increased acidity, the latter showing no change in acidity. Vinyl sulfonamide gave results contrary to those observed experimentally. The calculation suggested no increase in acidity, although one is observed experimentally. Part II. The synthesis was undertaken of several compounds capable of endocyclic nucleophilic substitution through a five-membered intermediate or transition state. The synthesis of two amino alcohols was unsuccessful. N-methyl-N-p-toluenesulfonyl-2-phenyl-ethylenediamine was synthesized and treated with n-butyllithium and lithium diisopropylamide. In each case, the anticipated rearrangement product was not observed. N-p-toluenesulfonyl-1,8-naphthosultam was also synthesized and treated with n-butyllithium and lithium diisopropylamide. The former resulted in nucleophilic attack of the base and ring opening. The latter resulted in an elimination-addition reaction yielding an undesired sultam. N-2-bromobenzyl-1,8-naphthosultam was also synthesized and treated with n-butyllithium. The sultam rearranged to a thiazocine through an endocyclic nucleophilic substitution, presumably by way of a five-membered intermediate or transition state, thus providing the first example of a rearrangement through this intermediate

Oligotrophy: the forgotten end of an ecological spectrum

Most studies that consider the relationship of diatoms and water quality have focused their attention on the questions and practicalities of water pollution or perturbations in some form or another. Many models and studies have demonstrated the environmental tolerances or changes in structure of diatom communities related to environmental challenges. This focus on the impacted end of the water quality spectrum has led, of necessity, to issues ultimately related to habitat restoration. We contend that a concentrated effort to develop more fully the theory and there is a need for practice related to oligotrophy, the other, ignored end of the water quality spectrum. We explore the historical usages of the term oligotrophy, as well as the challenges and promise of autecological and community approaches to understanding oligotrophy, and the possibility of focusing more on conservation rather than restoration in water quality issues

Quantitative morphometric methods in diatom research

Morphometric methods have been used in diatom research for decades. We present a review of the history of usage of morphometric methods of outline shape analysis, pattern recognition, and landmarkbased analysis. In addition, we present how morphometric methods are important in diatom taxonomy and classifi cation and what connections exist between morphometric methods and biologically meaningful results. Next, we present some details about calculating shape descriptors and using them in analysis of shape variation, the issues to be aware of, and what such results mean when defi ning shape groups as species groups. Finally, we provide a glimpse of the future in using morphometric methods in diatom research.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117649/1/bibl_diatom_62_strelnikova.pdfDescription of bibl_diatom_62_strelnikova.pdf : Main articl

Taxonomy and distribution of diatoms on the Turkish Mediterranean Coast, Dalyan (Muğla)

Diatoms are one of the components in the littoral zone and the most productive in terms of O2 production and primary production. Despite their importance in these coastal ecosystems, the diatoms of littoral zones of Turkish coastlines have been understudied.  In this report, we document the littoral diatoms from Dalyan Iztuzu Beach at the southeast coasts of Aegean Sea. Samples were collected from 6 stations in Dalyan Beach between 2012 and 2016. We report here on the occurrence of 9 genera including, Catenula Mereschkowsky, Cymatosira Grunow, Dimeregramma Ralfs, Diplomenora Blazé, Eunotogramma Weisse, Meloneis Louvrou, Danielidis & Economou-Amilli, Neohuttonia Kuntze, Plagiogramma Greville and Tetramphora Mereschkowsky, as well as 40 taxa as newly-recorded from Turkey. The newly-recorded diatoms are characterized in terms of their morphology and illustrated with light micrographs. For each species, their habitat and geographic distribution along the coasts are discussed

Diatom Diversity and Community Structure Along a Thermal Gradient in the Maple River of Northern Michigan

Articlehttp://deepblue.lib.umich.edu/bitstream/2027.42/96973/1/UMURF-Issue04_2007-AMaguire.pd

A VIRTUAL PROFESSIONAL LEARNING COMMUNITY SUPPORTING TECHNOLOGY INTEGRATION IN A 1:1 CHROMEBOOK SCHOOL DISTRICT

School district leaders provide public school teachers with technology to use in their classrooms without addressing the factors that affect implementation and integration to benefit students' learning. In the context of this study, technology implementation is defined as having access to and using technology, and technology integration is defined as incorporating technology confidently and successfully into the curriculum on a daily basis to support student learning and 21st century skills. The focus of the convergent parallel mixed-method study was to support technology integration for kindergarten through eighth grade classroom teachers through a virtual professional learning community (PLC). Framed around a constructivist and connectivist approach to learning, participants had access to support, resources, and collaboration through a virtual PLC that provided teachers with the opportunity to build their technology skills and confidence. The intervention was conducted from October 2020 to March 2021 with 15 participants from two schools. The study was conducted during the Coronavirus (COVID-19) pandemic. Qualitative and quantitative data were collected concurrently. Data analysis occurred qualitatively through thematic analysis and quantitatively through descriptive statistics. The overall results of the study revealed that the virtual PLC was able to provide support, resources, and collaboration opportunities for participants to build their technology skills and confidence, helping to foster technology integration. The discussion board section of the virtual PLC was found to be the most useful to the participants in providing support and collaboration opportunities. The virtual PLC was found to be successful in an extremely difficult school year

Comparison of upper respiratory viral load distributions in asymptomatic and symptomatic children diagnosed with SARS-CoV-2 infection in pediatric hospital testing programs

The distribution of upper respiratory viral loads (VL) in asymptomatic children infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unknown. We assessed PCR cycle threshold (Ct) values and estimated VL in infected asymptomatic children diagnosed in nine pediatric hospital testing programs. Records for asymptomatic and symptomatic patients with positive clinical SARS-CoV-2 tests were reviewed. Ct values were (i) adjusted by centering each value around the institutional median Ct value from symptomatic children tested with that assay and (ii) converted to estimated VL (numbers of copies per milliliter) using internal or manufacturer data. Adjusted Ct values and estimated VL for asymptomatic versus symptomatic children (118 asymptomatic versus 197 symptomatic children aged 0 to 4 years, 79 asymptomatic versus 97 symptomatic children aged 5 to 9 years, 69 asymptomatic versus 75 symptomatic children aged 10 to 13 years, 73 asymptomatic versus 109 symptomatic children aged 14 to 17 years) were compared. The median adjusted Ct value for asymptomatic children was 10.3 cycles higher than for symptomatic children