2,266 research outputs found
Photon collider search strategy for sleptons and dark matter at the LHC
We propose a search strategy using the LHC as a photon collider to open
sensitivity to scalar lepton (slepton ) production with masses
around 15 to 60 GeV above that of neutralino dark matter .
This region is favored by relic abundance and muon arguments.
However, conventional searches are hindered by the irreducible diboson
background. We overcome this obstruction by measuring initial state kinematics
and the missing momentum four-vector in proton-tagged ultraperipheral
collisions using forward detectors. We demonstrate sensitivity beyond LEP for
slepton masses of up to 220 GeV for GeV with 100 fb of 13 TeV proton
collisions. We encourage the LHC collaborations to open this forward frontier
for discovering new physics.Comment: 4 pages + bibliography, 3 figure
Intrinsic conduction through topological surface states of insulating BiTe epitaxial thin films
Topological insulators represent a novel state of matter with surface charge
carriers having a massless Dirac dispersion and locked helical spin
polarization. Many exciting experiments have been proposed by theory, yet,
their execution have been hampered by the extrinsic conductivity associated
with the unavoidable presence of defects in BiTe and BiSe bulk
single crystals as well as impurities on their surfaces. Here we present the
preparation of BiTe thin films that are insulating in the bulk and the
four-point probe measurement of the conductivity of the Dirac states on
surfaces that are intrinsically clean. The total amount of charge carriers in
the experiment is of order 10 cm only and mobilities up to 4,600
cm/Vs have been observed. These values are achieved by carrying out the
preparation, structural characterization, angle-resolved and x-ray
photoemission analysis, and the temperature dependent four-point probe
conductivity measurement all in-situ under ultra-high-vacuum conditions. This
experimental approach opens the way to prepare devices that can exploit the
intrinsic topological properties of the Dirac surface states.Comment: accepted for publication in Proceedings of the National Academy of
Sciences of the United States of America (PNAS
Thermal Degradation Pathways of Aqueous Diamine CO\u3csub\u3e2\u3c/sub\u3e Capture Solvents
Diamines have shown promise as CO2 capture solvents, yet very little is known about their pathway for thermal degradation. In this study, diamine thermal degradation was quantitatively monitored in lab-scale experiments on four aqueous diamine solvents; ethylenediamine (EDA) 1,2-propanediamine (1,2-DAP), 1,3-diaminopropane (1,3-DAP) and N-methyl-1,2-ethanediamine (NMEDA), to gain a more comprehensive understanding of their degradation pathway(s). The major degradation products were identified by high resolution time-of-flight mass spectrometry (TOF-MS). Degradation pathways were proposed showing that the primary thermal degradation route for this class of amine are through carbamate formation followed by intermolecular cyclization to form an imidazolidinone or nucleophilic attack by a free amine to form a diamine urea
Solubility and Thermodynamic Modeling of Carcinogenic Nitrosamines in Aqueous Amine Solvents for CO\u3csub\u3e2\u3c/sub\u3e Capture
A better understanding of key fundamental properties of nitrosamines, including their solubility in aqueous amine solvents, is needed to understand and accurately model the vapor-phase emission levels from operating CO2 capture systems. In this work, the first experimental Henry\u27s volatility coefficient of a nitrosamine was obtained with a novel method using static headspace solid phase micro extraction (SPME) and gas chromatography mass spectrometry (GC/MS). The experimentally determined Henry\u27s volatility coefficient of nitrosopyrrolidine (NPY) was found to be around 0.02 (dimensionless) at 25 °C, and falls in the range of a semi-volatile compound. A linear temperature dependency of the Henry\u27s volatility coefficient can be observed, however additional data is need to verify this trend
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Linked optical and gene expression profiling of single cells at high-throughput.
Single-cell RNA sequencing has emerged as a powerful tool for characterizing cells, but not all phenotypes of interest can be observed through changes in gene expression. Linking sequencing with optical analysis has provided insight into the molecular basis of cellular function, but current approaches have limited throughput. Here, we present a high-throughput platform for linked optical and gene expression profiling of single cells. We demonstrate accurate fluorescence and gene expression measurements on thousands of cells in a single experiment. We use the platform to characterize DNA and RNA changes through the cell cycle and correlate antibody fluorescence with gene expression. The platform's ability to isolate rare cell subsets and perform multiple measurements, including fluorescence and sequencing-based analysis, holds potential for scalable multi-modal single-cell analysis
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