5,361 research outputs found
Concerted reductive coupling of an alkyl chloride at Pt(IV)
Oxidation of a doubly cyclometallated platinum(II) complex results in two isomeric platinum(IV) complexes. Whereas the trans isomer is robust, being manipulable in air at room temperature, the cis isomer decomposes at −20 °C and above. Reductive coupling of an alkyl chloride at the cis isomer gives a new species which can be reoxidised. The independence of this coupling on additional halide rules out the reverse of an SN2 reaction, leaving a concerted process as the only sensible reaction pathway
Incoherently pumped continuous wave optical parametric oscillator broadened by non-collinear phasematching
In this paper, we report on a singly resonant optical parametric oscillator
(OPO) pumped by an amplified spontaneous emission (ASE) source. The pump
focusing conditions allow non-collinear phasematching, which resulted in a 230
nm (190 cm) spectral bandwidth. Calculations indicate that such
phasematching schemes may be used to further broaden OPO spectral bandwidths.Comment: 7 pages 4 figure
Mechanical Slosh Models for Rocket-Propelled Spacecraft
Several analytical mechanical slosh models for a cylindrical tank with flat bottom are reviewed. Even though spacecrafts use cylinder shaped tanks, most of those tanks usually have elliptical domes. To extend the application of the analytical models for a cylindrical tank with elliptical domes, the modified slosh parameter models are proposed in this report by mapping an elliptical dome cylindrical tank to a flat top/bottom cylindrical tank while maintaining the equivalent liquid volume. For the low Bond number case, the low-g slosh models were also studied. Those low-g models can be used for Bond number > 10. The current low-g slosh models were also modified to extend their applications for the case that liquid height is smaller than the tank radius. All modified slosh models are implemented in MATLAB m-functions and are collected in the developed MST (Mechanical Slosh Toolbox)
CD11cHi monocyte-derived macrophages are a major cellular compartment infected by Mycobacterium tuberculosis
During tuberculosis, lung myeloid cells have two opposing roles: they are an intracellular niche occupied by Mycobacterium tuberculosis, and they restrict bacterial replication. Lung myeloid cells from mice infected with yellow-fluorescent protein expressing M. tuberculosis were analyzed by flow cytometry and transcriptional profiling to identify the cell types infected and their response to infection. CD14, CD38, and Abca1 were expressed more highly by infected alveolar macrophages and CD11cHi monocyte-derived cells compared to uninfected cells. CD14, CD38, and Abca1 triple positive (TP) cells had not only the highest infection rates and bacterial loads, but also a strong interferon-gamma signature and nitric oxide synthetase-2 production indicating recognition by T cells. Despite evidence of T cell recognition and appropriate activation, these TP macrophages are a cellular compartment occupied by M. tuberculosis long-term. Defining the niche where M. tuberculosis resists elimination promises to provide insight into why inducing sterilizing immunity is a formidable challenge
Color Stability of Restorative Resins Under Accelerated Aging
The color stability of seven commercial composite resins, an unfilled resin, and three glazes was studied under conditions of accelerated aging by reflection spectrophotometry and visually with Munsell color tabs. After aging for 900 hours, most of the resins had lower values of luminous reflectance and excitation purity and higher values of dominant wavelength and contrast ratio compared to values at baseline.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66937/2/10.1177_00220345780570111101.pd
Hatching Eggs in the Classroom: A Teacher's Guide
12 pp., 2 tables, 1 data chart, lists of resources, references and suppliersScience projects involving eggs and embryos can lay the foundation for studies of the life sciences, introduce scientific methods and promote an appreciation for life. This manual is designed to aid classroom teachers in developing such projects and includes information on every step of the hatching process, from ordering the eggs to caring for the newly hatched chicks. For a companion video, order SP-7
A Vertically Integrated Geriatric Curriculum Improves Medical Student Knowledge and Clinical Skills
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65145/1/j.1532-5415.2007.01309.x.pd
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Synthesis and Structure of Solution-Stable One-Dimensional Palladium Wires
One-dimensional metal wires are valuable materials because of their optical and electronic anisotropy, and they have potential utility in devices such as photovoltaic cells and molecular sensors. However, despite more than a century of research, only a few examples exist of well-defined one-dimensional (1D) metal wires that allow for the rational variation of conductivity. Herein we describe the first examples of 1D molecular wires supported by Pd–Pd bonds, the thin-film conductive properties of which can be altered by controlled molecular changes. Wires based on Pd(III) give semiconducting films with a modifiable bandgap, whereas wires based on Pd(2.5) give films that display metallic conductivity above 200 K: a metallic state has not been reported previously for any polymer composed of 1D metal wires. The wires are infinite in the solid state and maintain 1D structures in solution with lengths of up to 750 nm. Solution stability enables thin film coating, a requisite for device fabrication using molecular wires.Chemistry and Chemical Biolog
Machine learning approaches for detecting tropical cyclone formation using satellite data
This study compared detection skill for tropical cyclone (TC) formation using models based on three different machine learning (ML) algorithms-decision trees (DT), random forest (RF), and support vector machines (SVM)-and a model based on Linear Discriminant Analysis (LDA). Eight predictors were derived from WindSat satellite measurements of ocean surface wind and precipitation over the western North Pacific for 2005-2009. All of the ML approaches performed better with significantly higher hit rates ranging from 94 to 96% compared with LDA performance (~77%), although false alarm rate by MLs is slightly higher (21-28%) than that by LDA (~13%). Besides, MLs could detect TC formation at the time as early as 26-30 h before the first time diagnosed as tropical depression by the JTWC best track, which was also 5 to 9 h earlier than that by LDA. The skill differences across MLs were relatively smaller than difference between MLs and LDA. Large yearly variation in forecast lead time was common in all models due to the limitation in sampling from orbiting satellite. This study highlights that ML approaches provide an improved skill for detecting TC formation compared with conventional linear approaches
Simple Clinical and Laboratory Predictors of Chikungunya versus Dengue Infections in Adults
10.1371/journal.pntd.0001786PLoS Neglected Tropical Diseases69
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