Understanding the origin and dynamics of hadron structure and in turn that of atomic nuclei is a central goal of nuclear physics. This challenge entails the questions of how does the roughly 1 GeV mass-scale that characterizes atomic nuclei appear; why does it have the observed value; and, enigmatically, why are the composite Nambu-Goldstone (NG) bosons in quantum chromodynamics (QCD) abnormally light in comparison? In this perspective, we provide an analysis of the mass budget of the pion and proton in QCD; discuss the special role of the kaon, which lies near the boundary between dominance of strong and Higgs mass-generation mechanisms; and explain the need for a coherent effort in QCD phenomenology and continuum calculations, in exa-scale computing as provided by lattice QCD, and in experiments to make progress in understanding the origins of hadron masses and the distribution of that mass within them. We compare the unique capabilities foreseen at the electron-ion collider (EIC) with those at the hadron-electron ring accelerator (HERA), the arXiv:1907.08218v2 [nucl-ex] Rikutaro Yoshida (ryoshida@jlab.org) INTRODUCTIONAtomic nuclei lie at the core of everything we can see; and at the first level of approximation, their atomic weights are simply the sum of the masses of all the neutrons and protons (nucleons) they contain. Each nucleon has a mass m N ∼ 1 GeV, i.e. approximately 2000-times the electron mass. The Higgs boson produces the latter, but what produces the masses of the neutron and proton? This is the crux: the vast majority of the mass of a nucleon is lodged with the energy needed to hold quarks together inside it; and that is supposed to be explained by QCD, the strong-interaction piece within the Standard Model.QCD is unique. It is a fundamental theory with the capacity to sustain massless elementary degrees-of-freedom, viz. gluons and quarks; yet gluons and quarks are predicted to acquire mass dynamically [1][2][3], and nucleons and almost all other hadrons likewise, so that the only massless systems in QCD are its composite NG bosons [4,5], e.g. pions and kaons. Responsible for binding systems as diverse as atomic nuclei and neutron stars, the energy associated with the gluons and quarks within these Nambu-Goldstone (NG) modes is not readily apparent. This is in sharp and fascinating contrast with all other "everyday" hadronic bound states, viz. systems constituted from up = u, down = d, and/or strange = s quarks, which possess nuclear-size masses far in excess of anything that can directly be tied to the Higgs boson. 1
Major concerns in the development of wearable textile electronics are exposure to moisture and contamination. The exposure can cause electrical breakdown of the device and its interconnections, and thus continuous efforts have been made to fabricate textile electronics which are free from moisture and pollution. Herein, we developed a highly conductive and waterproof fiber with excellent electrical conductivity (0.11 Ω/cm) and mechanical stability for advanced interconnector components in wearable textile electronics. The fabrication process of the highly conductive fiber involves coating of a commercial Kevlar fiber with Ag nanoparticle-poly(styrene- block-butadiene- block-styrene) polymer composites. The fabricated fiber then gets treated with self-assembled monolayer (SAM)-forming reagents, which yields waterproof and self-cleaning properties. To find optimal SAM-forming reagents, four different kinds of reagents involving 1-decane thiol (DT), 1 H,1 H,2 H,2 H-perfluorohexanethiol, 1 H,1 H,2 H,2 H-perfluorodecyltrichlorosilane, 1 H,1 H,2 H,2 H-perfluodecanethiol (PFDT) were compared in terms of their thiol group and carbon chain lengths. Among the SAM-forming reagents, the PFDT-treated conductive fiber showed superior waterproof and self-cleaning property, as well as great sustainability in the water with varying pH because of nanoscale roughness and low surface energy. In addition, the functionality of the conductive fiber was tested under mechanical compression via repeated washing and folding processes. The developed conductive fiber with waterproof and self-cleaning property has promising applications in the interconnector operated under water and textile electronics.
Supporting Information. The Supporting Information is available free of charge on the ACS Publications website at DOI: The SEM and TEM images of well dispersed HA/SWCNT solutions with 7 mg/mL SWCNTs; Chemical modification sites in HA and the schematic representations of HA crosslinked with HMDA after activation using EDC and HOBt; FTIR spectra of SWCNTs, uncrosslinked and crosslinked HA/SWCNT microfibers; 3D topography of uncrosslinked and crosslinked HA/CNTs microfiebrs with 7 mg/mL SWCNT concentration obtained using AFM; Tensile strength of uncrosslinked and crosslinked swollen HA/SWCNT microfibers as a function of SWCNT concentration; Failure strain of uncrosslinked and crosslinked swollen HA/SWCNT microfibers as a function of SWCNT concentration; SEM images of well dispersed HA/SWCNT solutions with 4 mg/mL and 7 mg/mL SWCNTs; Micrographs and SEM of HA/SWCNT dispersion with different SWCNT concentrations; Schematic illustration of the HA/SWCNT microfibers on the paper frame with different bending angles; Schematic illustration of the specimen (bottom), photographs of the fibers being tested in a tensile tester at rest (left) and maximum strain (right), and the corresponding load-displacement curve (middle); Cyclic voltammetry outcome of the HA/SWCNT microfibers with 7 mg/mL SWCNT concentration: current vs. scan rate; Viability of NIH-3T3 fibroblasts after five days of culture on the surface of HA/SWCNT microfibers with 7 mg/mL SWCNT concentration; The authors declare no competing financial interest.
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