Recently, we presented a new approach for a compact radio-frequency (RF) accelerator structure and demonstrated the functionality of the individual components: acceleration units and focusing ...elements. In this paper, we combine these units to form a working accelerator structure including a matching section between the ion source extraction grids and the RF-acceleration unit. The matching section consist of six electrostatic quadrupoles (ESQs) fabricated using 3D-printing techniques. The matching section enables us to capture twice the amount of beam and match the beam envelope to conditions for an acceleration lattice. We present data from an integrated accelerator consisting of the source, matching section, and an ESQ doublet sandwiched between two RF-acceleration units.
The T cell antigen receptor (TCR) recognizes antigen in the form of short peptides bound to a major histocompatibility (MHC) molecule. This review provides a synopsis of the current state of ...knowledge of the structure and function of the receptor and its possible role in human disease. Analysis of the T cell receptor usage of T-cell lines and clones recognizing the same peptide-MHC complex is beginning to shed light onto the structural basis of the TCR-peptide-MHC complex. Also, it is now apparent that there are two mechanisms by which the TCR can interact with the MHC molecule, either through classical peptide interactions or through super-antigens. Finally, we review the role of specific TCRs in human disease. Current evidence in this area is difficult to interpret; however, it is likely that TCR-mediated disease susceptibility exists, and its basis at either a germline or somatic level will soon be clarified.
The cell surface molecules CD4 and CD8 greatly enhance the sensitivity of T-cell antigen recognition, acting as "co-receptors" by binding to the same major histocompatibility complex (MHC) molecules ...as the T-cell receptor (TCR). Here we use surface plasmon resonance to study the binding of CD8 alpha alpha to class I MHC molecules. CD8 alpha alpha bound the classical MHC molecules HLA- A*0201, -A*1101, -B*3501, and -C*0702 with dissociation constants (K sub(d)) of 90-220 mu M, a range of affinities distinctly lower than that of TCR/peptide-MHC interaction. We suggest such affinities apply to most CD8 alpha alpha /classical class I MHC interactions and may be optimal for T-cell recognition. In contrast, CD8 alpha alpha bound both HLA-A*6801 and B*4801 with a significantly lower affinity ( greater than or equal to 1 mM), consistent with the finding that interactions with these alleles are unable to mediate cell-cell adhesion. Interestingly, CD8 alpha alpha bound normally to the nonclassical MHC molecule HLA-G (K sub(d) similar to 150 mu M), but only weakly to the natural killer cell receptor ligand HLA-E (K sub(d) greater than or equal to 1 mM). Site-directed mutagenesis experiments revealed that variation in CD8 alpha alpha binding affinity can be explained by amino acid differences within the alpha 3 domain. Taken together with crystallographic studies, these results indicate that subtle conformational changes in the solvent exposed alpha 3 domain loop (residues 223-229) can account for the differential ability of both classical and nonclassical class I MHC molecules to bind CD8.
This white paper submitted for 2020 Decadal Assessment of Plasma Science concerns the importance of multi-spacecraft missions to address fundamental questions concerning plasma turbulence. Plasma ...turbulence is ubiquitous in the universe, and it is responsible for the transport of mass, momentum, and energy in such diverse systems as the solar corona and wind, accretion discs, planet formation, and laboratory fusion devices. Turbulence is an inherently multi-scale and multi-process phenomenon, coupling the largest scales of a system to sub-electron scales via a cascade of energy, while simultaneously generating reconnecting current layers, shocks, and a myriad of instabilities and waves. The solar wind is humankind's best resource for studying the naturally occurring turbulent plasmas that permeate the universe. Since launching our first major scientific spacecraft mission, Explorer 1, in 1958, we have made significant progress characterizing solar wind turbulence. Yet, due to the severe limitations imposed by single point measurements, we are unable to characterize sufficiently the spatial and temporal properties of the solar wind, leaving many fundamental questions about plasma turbulence unanswered. Therefore, the time has now come wherein making significant additional progress to determine the dynamical nature of solar wind turbulence requires multi-spacecraft missions spanning a wide range of scales simultaneously. A dedicated multi-spacecraft mission concurrently covering a wide range of scales in the solar wind would not only allow us to directly determine the spatial and temporal structure of plasma turbulence, but it would also mitigate the limitations that current multi-spacecraft missions face, such as non-ideal orbits for observing solar wind turbulence. Some of the fundamentally important questions that can only be addressed by in situ multipoint measurements are discussed.
To obtain a supercapacitor with a remarkable specific capacitance and rate performance, a cogent design and synthesis of the electrode material containing abundant active sites is necessary. In ...present work, a scalable strategy is developed for preparing 2D‐on‐2D nanostructures for high‐energy solid‐state asymmetric supercapacitors (ASCs). The self‐assembled vertically aligned microsheet‐structured 2D nickel pyrophosphate (Ni2P2O7) is decorated with amorphous bimetallic nickel cobalt hydroxide (NiCo‐OH) to form a 2D‐on‐2D nanostructure arrays electrode. The resulting Ni2P2O7/NiCo‐OH 2D‐on‐2D array electrode exhibits peak specific capacity of 281 mA hg−1 (4.3 F cm−2), excellent rate capacity, and cycling stability over 10 000 charge–discharge cycles in the positive potential range. The excellent electrochemical features can be attributed to the high electrical conductivity and 2D layered structure of Ni2P2O7 along with the Faradic capacitance of the amorphous NiCo‐OH nanosheets. The constructed Ni2P2O7/NiCo‐OH//activated carbon based solid‐state ASC cell operates in a high voltage window of 1.8 V with an energy density of 78 Wh kg−1 (1.065 mWh cm−3) and extraordinary cyclic stability over 10 000 charge–discharge cycles with excellent energy efficiency (75%–80%) over all current densities. The excellent electrochemical performance of the prepared electrode and solid‐state ASC device offers a favorable and scalable pathway for developing advanced electrodes.
A 2D‐on‐2D nanostructure has been developed by the scalable strategy for high‐energy solid‐state asymmetric supercapacitors (ASC). The constructed solid‐state ASC cell operates in a high voltage window of 1.8 V with an energy density of 78 Wh kg−1 (1.065 mWh cm−3) and extraordinary cyclic stability over 10 000 charge–discharge cycles with excellent energy efficiency over all current densities.
No validated high-performance liquid chromatography (HPLC) methods for the determination of vitamin E in algae have been reported. We developed and evaluated a new procedure for the quantitation of ...microalgal α- and γ-tocopherol (α-T and γ-T) using reversed-phase HPLC with fluorescence detection. The compounds of interest were extracted with a mixture of petroleum ether-diisopropyl ether (3:1, v/v) after saponification in the presence of pyrogallol. δ-Tocopherol (δ-T) or tocol was used as an internal standard. Linearity was achieved (
r>0.999) over the range of 0.11∼2.32 μg/,l for α-T and 0.02∼0.23 μg/ml for γ-T. The within-run coefficients of variation for repetitive analysis were 1.9%, 1.7% and 1.0% (
n=10) for α-T at concentrations of 0.09, 1.24 and 1.55 μg/ml, and 1.9%, 0.8% and 0.3% (
n=10) for γ-T at concentrations of 0.02, 0.08 and 0.23 μg/ml, respectively. The recoveries at low concentration levels (0.11 and 0.02 μg/ml) were 82.4% and 96.2% (
n=5) for α-T and γ-T, respectively. For medium concentrations (0.78 and 0.12 μg/ml) and high concentrations (2.32 and 0.20 μg/ml), the recoveries were 94.3∼98.7% for the two tocopherols. The limits of quantitation of α-T and γ-T were 20 and 5 μg/g dry mass, respectively. This method has been routinely used as part of nutritional studies on fish and shrimp larvae fed on microalgae.
Large‐scale electrical energy storage has become more important than ever for reducing fossil energy consumption in transportation and for the widespread deployment of intermittent renewable energy ...in electric grid. However, significant challenges exist for its applications. Here, the status and challenges are reviewed from the perspective of materials science and materials chemistry in electrochemical energy storage technologies, such as Li‐ion batteries, sodium (sulfur and metal halide) batteries, Pb‐acid battery, redox flow batteries, and supercapacitors. Perspectives and approaches are introduced for emerging battery designs and new chemistry combinations to reduce the cost of energy storage devices.
The different applications of energy storage, different technologies, and the cost requirements from the kilowatt to gigawatt scale are compared. Li‐ion batteries have attracted attention for transportation storage, while many other technologies are considered for stationary applications.
MIR-491 is commonly co-deleted with its adjacent CDKN2A on chromosome 9p21.3 in glioblastoma multiforme (GBM). However, it is not known whether deletion of MIR-491 is only a passenger event or has an ...important role. Small-RNA sequencing of samples from GBM patients demonstrated that both mature products of MIR-491 (miR-491-5p and -3p) are downregulated in tumors compared with the normal brain. The integration of GBM data from The Cancer Genome Atlas (TCGA), miRNA target prediction and reporter assays showed that miR-491-5p directly targets EGFR, CDK6 and Bcl-xL, whereas miR-491-3p targets IGFBP2 and CDK6. Functionally, miR-491-3p inhibited glioma cell invasion; overexpression of both miR-491-5p and -3p inhibited proliferation of glioma cell lines and impaired the propagation of glioma stem cells (GSCs), thereby prolonging survival of xenograft mice. Moreover, knockdown of miR-491-5p in primary Ink4a-Arf-null mouse glial progenitor cells exacerbated cell proliferation and invasion. Therefore, MIR-491 is a tumor suppressor gene that, by utilizing both mature forms, coordinately controls the key cancer hallmarks: proliferation, invasion and stem cell propagation.
Multimessenger observations of the neutron star merger GW170817 and its kilonova proved that neutron star mergers can synthesize large quantities of r-process elements. If neutron star mergers in ...fact dominate all r-process element production, then the distribution of kilonova ejecta compositions should match the distribution of r-process abundance patterns observed in stars. The lanthanide fraction (XLa) is a measurable quantity in both kilonovae and metal-poor stars, but it has not previously been explicitly calculated for stars. Here we compute the lanthanide fraction distribution of metal-poor stars (Fe/H < − 2.5) to enable comparison to current and future kilonovae. The full distribution peaks at log XLa ∼ −1.8, but r-process-enhanced stars (Eu/Fe > 0.7) have distinctly higher lanthanide fractions: . We review observations of GW170817 and find general consensus that the total , somewhat lower than the typical metal-poor star and inconsistent with the most highly r-enhanced stars. For neutron star mergers to remain viable as the dominant r-process site, future kilonova observations should be preferentially lanthanide-rich (including a population of ∼10% with ). These high-XLa kilonovae may be fainter and more rapidly evolving than GW170817, posing a challenge for discovery and follow-up observations. Both optical and (mid-)infrared observations will be required to robustly constrain kilonova lanthanide fractions. If such high-XLa kilonovae are not found in the next few years, that likely implies that the stars with the highest r-process enhancements have a different origin for their r-process elements.
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