35,829 research outputs found

    Metastable Innershell Molecular State (MIMS)

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    We propose that the existence of Metastable Innershell Molecular State (MIMS) was experimentally discovered by Bae et al. in hypervelocity (v>100km/s) impact of nanoparticles. The decay of MIMS resulted in the observed intense soft x-rays in the range of 75 - 100 eV in agreement with Winterberg's recent prediction.Comment: Submitted to Physics Letters

    Letter from Cammie Williams to Mims Williams

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    Letter from Cammie Williams to his brother, Mims Williams, regarding the education of Gordon Williams (Cammie\u27s son) and Mims Williams (Mims\u27 son).https://scholarsjunction.msstate.edu/mss-williams-papers/1049/thumbnail.jp

    Chemically modified polysulfones for molecular imprinting. Synthesis and complexation with a fluorescent model template

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    Polysulfone (PSU) was chemically modified to prepare new molecular imprinted membranes (MIMs). Several amounts of amine and sulfonyl groups were introduced into the PSU chemical structure in order to create interactions with acid or base templates, such as biomolecules or biomacromolecules. A fluorescent dye, Acridine Orange base (AO), was used as a model template and its complexation with the prepared PSUs was monitored by spectroscopic techniques. This study showed an absence of complexation with the native PSU and a strong complexation with the aminated and the sulfonated PSUs. Partially allylated PSU bearing amine or sulfonyl groups were also synthesized. These compounds are expected to be used as precursors for designing new crosslinked molecular imprinting membranes (MIMs), exhibiting high stability of the template memory

    Segmentation of Multi-Isotope Imaging Mass Spectrometry Data for Semi-Automatic Detection of Regions of Interest

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    Multi-isotope imaging mass spectrometry (MIMS) associates secondary ion mass spectrometry (SIMS) with detection of several atomic masses, the use of stable isotopes as labels, and affiliated quantitative image-analysis software. By associating image and measure, MIMS allows one to obtain quantitative information about biological processes in sub-cellular domains. MIMS can be applied to a wide range of biomedical problems, in particular metabolism and cell fate [1], [2], [3]. In order to obtain morphologically pertinent data from MIMS images, we have to define regions of interest (ROIs). ROIs are drawn by hand, a tedious and time-consuming process. We have developed and successfully applied a support vector machine (SVM) for segmentation of MIMS images that allows fast, semi-automatic boundary detection of regions of interests. Using the SVM, high-quality ROIs (as compared to an expert's manual delineation) were obtained for 2 types of images derived from unrelated data sets. This automation simplifies, accelerates and improves the post-processing analysis of MIMS images. This approach has been integrated into “Open MIMS,” an ImageJ-plugin for comprehensive analysis of MIMS images that is available online at http://www.nrims.hms.harvard.edu/NRIMS_ImageJ.php

    Chemically modified polysulfones for molecular imprinting. Synthesis and complexation with a fluorescent model template

    Get PDF
    Polysulfone (PSU) was chemically modified to prepare new molecular imprinted membranes (MIMs). Several amounts of amine and sulfonyl groups were introduced into the PSU chemical structure in order to create interactions with acid or base templates, such as biomolecules or biomacromolecules. A fluorescent dye, Acridine Orange base (AO), was used as a model template and its complexation with the prepared PSUs was monitored by spectroscopic techniques. This study showed an absence of complexation with the native PSU and a strong complexation with the aminated and the sulfonated PSUs. Partially allylated PSU bearing amine or sulfonyl groups were also synthesized. These compounds are expected to be used as precursors for designing new crosslinked molecular imprinting membranes (MIMs), exhibiting high stability of the template memory

    Letter to Mims Williams

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    Letter to Mims Williams from his brother, Cammie Williams, in Dry Grove, Mississippi, regarding the closing of the W. C. Ellis Co. (where Mims worked). He also asks if Mims will go to Washington on March 4; March 4, 1913 was the inauguration of President Woodrow Wilson.https://scholarsjunction.msstate.edu/mss-williams-papers/1166/thumbnail.jp

    Development of a method for in situ measurement of denitrification in aquifers using 15N tracer tests and membrane inlet mass spectrometry

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    We present a new approach for in situ-measurement of denitrification using a combination of 15N-tracer push-pull experiments with in situ analysis of 15N-labled N2 and N2O using membrane inlet mass spectrometry (MIMS). In the 15N-tracer experiment we present here we supplemented Aquifer material of two depths with 15N labeled nitrate. The results of our laboratory 15N-tracer test showed a linear increase of denitrification products (15(N2O+N2)) over time. At the end of our experiment we measured up to 1500 and 3700 µg/L 15(N2O+N2) in the water samples from the supplemented aquifer material. The online measurement with MIMS enabled us to see during the experiment if and when the production of the labeled denitrification products started. We took also parallel samples for isotope ratio mass spectrometry (IRMS) analysis to check our MIMS measurements. The measured 15(N2O+N2) values for IRMS matches the MIMS measurements very well. With the MIMS-method there is no need for sample preparation and so we were able to run the MIMS part of the 15N-tracer test automatically. Later-on this approach will be used in the field

    Dissolved methane pluming mapping using Membrane Inlet Mass-Spectrometry (MIMS) at a blowout site in the North Sea

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    A blow out site in the North Sea (well 22/4-b, UK EEZ) in a water depth of 83 m, served as a test area to demonstrate MIMS as a powerful tool for the continuous measurement of dissolved methane simultaneously to the partial pressure of carbon dioxide, nitrogen and oxygen as well as other gases. A pump-CTD arrangement was used to generate a continuous water stream through a 2.5 cm thick tube to the ship laboratory and was analyzed using a membrane inlet quadrupole mass spectrometer (GAM 200, InProcessInstruments). The pump-CTD was further equipped with calibrated HydroC CH4/CO2 sensors. The MIMS measurements were conducted under fully controlled temperature conditions and were calibrated for CH4, N2, O2, and pCO2. The pump-CTD arrangement was towed along transects across the blow out and dissolved gas concentrations as well as physical water column data were synchronized and geo-referenced. The transects were repeated in three different depth layers, including a bottom layer of � 2 m above the sea floor, 60 m above the sea floor just below the thermocline and a third plane in 10 m water depth. During the tows water samples were taken for later onboard methane analysis and cross-calibration with the MIMS and HydroC data. After data selection under consideration of the tidal regime lateral and vertical plume dimensions of dissolved methane were constructed. Dissolved methane concentrations ranged between background and up to about 18�M. Below the thermocline, which represents an effective barrier for the vertical distribution of dissolved methane, methane distinctively spreads laterally. Only at locations were the gas bubble stream and concurrently advected water from below the thermocline reaches the sea surface enhanced methane emission into the atmosphere took place

    On-line mass spectrometry: membrane inlet sampling

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    Significant insights into plant photosynthesis and respiration have been achieved using membrane inlet mass spectrometry (MIMS) for the analysis of stable isotope distribution of gases. The MIMS approach is based on using a gas permeable membrane to enable the entry of gas molecules into the mass spectrometer source. This is a simple yet durable approach for the analysis of volatile gases, particularly atmospheric gases. The MIMS technique strongly lends itself to the study of reaction flux where isotopic labeling is employed to differentiate two competing processes; i.e., O2 evolution versus O2 uptake reactions from PSII or terminal oxidase/rubisco reactions. Such investigations have been used for in vitro studies of whole leaves and isolated cells. The MIMS approach is also able to follow rates of isotopic exchange, which is useful for obtaining chemical exchange rates. These types of measurements have been employed for oxygen ligand exchange in PSII and to discern reaction rates of the carbonic anhydrase reactions. Recent developments have also engaged MIMS for online isotopic fractionation and for the study of reactions in inorganic systems that are capable of water splitting or H2 generation. The simplicity of the sampling approach coupled to the high sensitivity of modern instrumentation is a reason for the growing applicability of this technique for a range of problems in plant photosynthesis and respiration. This review offers some insights into the sampling approaches and the experiments that have been conducted with MIMS
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