Synthesis of fluorinated alkoxyamines and alkoxyamine-initiated nitroxide-mediated precipitation polymerizations of styrene in supercritical carbon dioxide

TIPNO (2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide)-alkoxyamine was found to give reasonably controlled/living nitroxide-mediated (NMP) precipitation polymerizations of styrene in supercritical carbon dioxide (scCO(2)). In contrast under the same conditions, the analogous SG1 (N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl)nitroxide)-alkoxyamine gave higher rates of polymerization and inferior controlled/living character. The circumvention of the requirement for excess free (nitroxide](0) allowed the study of nitroxide partitioning effects in scCO(2) for three newly synthesized fluorinated alkoxyamines. Two alkoxyamines dissociated into scCO(2)-philic fluorinated TIPNO-nitroxide derivatives, while another contains a similar sized fluorinated "foot". Despite the increased steric bulk about the N-O bond for the novel fluorinated alkoxyamines, all polymerizations proceeded at a similar rate and level of control to the TIPNO system in solution (toluene). PREDICI simulations for the styrene/TIPNO system are used to support extensive partitioning effects observed in scCO(2) for the fluorinated alkoxyamines.Irish Research Council (formerly IRCSET) IUPAC Transnational Call in Polymer Chemistry to F.Aldabbagh. National Science Foundation (NSF CHE-1057927, USA) to R. Braslau.peer-reviewe

A communal catalogue reveals Earth's multiscale microbial diversity

Our growing awareness of the microbial world's importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth's microbial diversity.Peer reviewe

A communal catalogue reveals Earth’s multiscale microbial diversity

Our growing awareness of the microbial world’s importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth’s microbial diversity

Synthesis of Fluorinated Alkoxyamines for Nitroxide Mediated Precipitation Polymerization in Supercritical Carbon Dioxide

Three novel fluorinated alkoxyamines were synthesized for nitroxide-mediated precipitation polymerization (NMP) of styrene in supercritical carbon dioxide. The polymerizations were conducted in supercritical carbon dioxide without excess free nitroxide to allow for a detailed study on nitroxide partitioning. The addition of a fluorinated moiety allowed for increased partitioning relative to the parent nitroxide into supercritical carbon dioxide. The loss of control over the polymerization due to nitroxide partitioning did not have a significant influence on the polymerization rate. Synthesis of polyfluorinated macroinitiators by atom transfer radical polymerization (ATRP) of fluorinated monomers was explored but thwarted due to a lack of solubility. The increased fluorine content due to polymerization of fluorinated monomers would have allowed direct control over the quantity of fluorine added to the macroinitiator and potentially influenced the quantity of nitroxide partitioning

Synthesis of Fluorinated Alkoxyamines for Nitroxide Mediated Precipitation Polymerization in Supercritical Carbon Dioxide

Three novel fluorinated alkoxyamines were synthesized for nitroxide-mediated precipitation polymerization (NMP) of styrene in supercritical carbon dioxide. The polymerizations were conducted in supercritical carbon dioxide without excess free nitroxide to allow for a detailed study on nitroxide partitioning. The addition of a fluorinated moiety allowed for increased partitioning relative to the parent nitroxide into supercritical carbon dioxide. The loss of control over the polymerization due to nitroxide partitioning did not have a significant influence on the polymerization rate. Synthesis of polyfluorinated macroinitiators by atom transfer radical polymerization (ATRP) of fluorinated monomers was explored but thwarted due to a lack of solubility. The increased fluorine content due to polymerization of fluorinated monomers would have allowed direct control over the quantity of fluorine added to the macroinitiator and potentially influenced the quantity of nitroxide partitioning

Synthesis of fluorinated alkoxyamines and alkoxyamine-initiated nitroxide-mediated precipitation polymerizations of styrene in supercritical carbon dioxide

TIPNO (2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide)-alkoxyamine was found to give reasonably controlled/living nitroxide-mediated (NMP) precipitation polymerizations of styrene in supercritical carbon dioxide (scCO(2)). In contrast under the same conditions, the analogous SG1 (N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl)nitroxide)-alkoxyamine gave higher rates of polymerization and inferior controlled/living character. The circumvention of the requirement for excess free (nitroxide](0) allowed the study of nitroxide partitioning effects in scCO(2) for three newly synthesized fluorinated alkoxyamines. Two alkoxyamines dissociated into scCO(2)-philic fluorinated TIPNO-nitroxide derivatives, while another contains a similar sized fluorinated "foot". Despite the increased steric bulk about the N-O bond for the novel fluorinated alkoxyamines, all polymerizations proceeded at a similar rate and level of control to the TIPNO system in solution (toluene). PREDICI simulations for the styrene/TIPNO system are used to support extensive partitioning effects observed in scCO(2) for the fluorinated alkoxyamines

Early life predictors of alcohol-related attitudes among 11-year-old never drinkers

Alcohol-related attitudes are evident before children have personal experience drinking alcohol and represent key proximal predictors of alcohol use, but relatively little is known about how early life characteristics predict these attitudes. Among late childhood lifetime alcohol abstainers (M(age)=10.67 years; 51% girls), we examine predictors of positive alcohol expectancies and perceived risk of alcohol use. Data from the Millennium Cohort Study, an ongoing nationally representative longitudinal study of children born in the UK, were available from 11,097 children who completed the self-report survey at modal age 11 and reported never drinking alcohol. A sequential structural model suggested that sociodemographic factors were distal predictors of age 11 alcohol attitudes that operated, in part, through family and child risk factors (measured at ages 3 to 7). Alcohol attitudes varied by sociodemographics; for example, boys had higher positive expectancies than girls and White British children had higher positive expectancies and lower perceived risk than Black British and Asian British children. In terms of family factors, parent alcohol problems predicted children’s lower perceived risk, and higher parent-child conflict predicted more positive expectancies. For child factors, children’s greater cognitive skills predicted higher perceived risk, and internalizing problems predicted more positive expectancies. Indirect effects from sociodemographics through parent-child conflict and internalizing problems predicted positive expectancies; indirect effects through parent alcohol problems and cognitive skills predicted perceived risk. Future research should delve further into mechanisms underlying the development of alcohol attitudes and their potential as malleable targets for prevention