5,383 research outputs found
6.0.A Daily Outline
WELCOME to WINDOWS on the INQUIRY CLASSROOM!
You have landed on a piece of a National Science Foundation Project (DUE 1245730) directed by Professor Chris Bauer, Chemistry Department, University of New Hampshire. This is one part of a completely documented inquiry-based university science course called “Fire & Ice” which explores the nature of heat and temperature. There are multiple video perspectives and commentary from instructors and students, and documents of all course materials (agenda, instructions, student work). It’s too complicated to explain here. Take a look at the user orientation document at this link
6.0.C.1 Hands-on Phase Properties of Gases
WELCOME to WINDOWS on the INQUIRY CLASSROOM!
You have landed on a piece of a National Science Foundation Project (DUE 1245730) directed by Professor Chris Bauer, Chemistry Department, University of New Hampshire. This is one part of a completely documented inquiry-based university science course called “Fire & Ice” which explores the nature of heat and temperature. There are multiple video perspectives and commentary from instructors and students, and documents of all course materials (agenda, instructions, student work). It’s too complicated to explain here. Take a look at the user orientation document at this link
Effect of Retention Aids on AKD Size Response and Permanence
Poor size response and size reversion have been major concerns with the use of an alkyl ketene dimer (AKD) sizing system. Poor retention of calcium carbonate fillers and fiber fines are believed to be the cause of poor size response. A number of materials, including carbonate fillers, promoters and retention aids are believed to contribute to size reversion.
The focus of this study was to determine the effectiveness of retention aids in obtaining good size response. Size permanence was also studied The performance of the retention aides were studied by preparing handsheets at five different zeta potentials.
It was determined that when no retention aid was added to the system, size response was not dependent on zeta potential. It was dependent on the amount of polyethyleneimine (PEI) present in the system. Low sizing levels in the absence of PEI indicate poor retention of the size molecules.
When cationic polymers were added to the stock, sizing levels showed a dramatic increase. This increase was do to superior retention of the fiber fines. As zeta potential was increased to highly cationic, size levels dropped due to poor retention of the sizing chemical. Cationic polymer was not observed to contribute to size reversion.
Size response with the addition of an anionic polymer was highly dependent on the presence of a cationic fixative. When no PEI was present in the stock, the anionic polymer was ineffective. Small amounts of PEI provided cationic sites for the anionic polymer to bridge the fibers. Contrary to previous literature studies, the anionic polymer did not contribute to size reversion.
When PEI was added to the system, large increases in sizing levels were observed PEI promotes excellent retention of the fiber fines. Good fines retention will increase sizing levels. Not only did PEI promote the reaction between AKD and cellulose, no size reversion was observed when it was used
Altered thymic differentiation and modulation of arthritis by invariant NKT cells expressing mutant ZAP70
Various subsets of invariant natural killer T (iNKT) cells with different cytokine productions develop in the mouse thymus, but the factors driving their differentiation remain unclear. Here we show that hypomorphic alleles of Zap70 or chemical inhibition of Zap70 catalysis leads to an increase of IFN-gamma-producing iNKT cells (NKT1 cells), suggesting that NKT1 cells may require a lower TCR signal threshold. Zap70 mutant mice develop IL-17-dependent arthritis. In a mouse experimental arthritis model, NKT17 cells are increased as the disease progresses, while NKT1 numbers negatively correlates with disease severity, with this protective effect of NKT1 linked to their IFN-gamma expression. NKT1 cells are also present in the synovial fluid of arthritis patients. Our data therefore suggest that TCR signal strength during thymic differentiation may influence not only IFN-gamma production, but also the protective function of iNKT cells in arthritis
tRNA functional signatures classify plastids as late-branching cyanobacteria.
BackgroundEukaryotes acquired the trait of oxygenic photosynthesis through endosymbiosis of the cyanobacterial progenitor of plastid organelles. Despite recent advances in the phylogenomics of Cyanobacteria, the phylogenetic root of plastids remains controversial. Although a single origin of plastids by endosymbiosis is broadly supported, recent phylogenomic studies are contradictory on whether plastids branch early or late within Cyanobacteria. One underlying cause may be poor fit of evolutionary models to complex phylogenomic data.ResultsUsing Posterior Predictive Analysis, we show that recently applied evolutionary models poorly fit three phylogenomic datasets curated from cyanobacteria and plastid genomes because of heterogeneities in both substitution processes across sites and of compositions across lineages. To circumvent these sources of bias, we developed CYANO-MLP, a machine learning algorithm that consistently and accurately phylogenetically classifies ("phyloclassifies") cyanobacterial genomes to their clade of origin based on bioinformatically predicted function-informative features in tRNA gene complements. Classification of cyanobacterial genomes with CYANO-MLP is accurate and robust to deletion of clades, unbalanced sampling, and compositional heterogeneity in input tRNA data. CYANO-MLP consistently classifies plastid genomes into a late-branching cyanobacterial sub-clade containing single-cell, starch-producing, nitrogen-fixing ecotypes, consistent with metabolic and gene transfer data.ConclusionsPhylogenomic data of cyanobacteria and plastids exhibit both site-process heterogeneities and compositional heterogeneities across lineages. These aspects of the data require careful modeling to avoid bias in phylogenomic estimation. Furthermore, we show that amino acid recoding strategies may be insufficient to mitigate bias from compositional heterogeneities. However, the combination of our novel tRNA-specific strategy with machine learning in CYANO-MLP appears robust to these sources of bias with high accuracy in phyloclassification of cyanobacterial genomes. CYANO-MLP consistently classifies plastids as late-branching Cyanobacteria, consistent with independent evidence from signature-based approaches and some previous phylogenetic studies
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Release of soluble metal ions from copper based dental alloys mesured by ICP-MS
Describes the release of soluble metal ions from copper based dental alloys mesured by ICP-MS. Presented at the annual congress of the british toxicology society
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