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bstract
In the purely gravitational dark matter scenario, the dark matter particle does not have any interaction except for gravitational one. We study the gravitational particle production of dark ...matter particle in such a minimal setup and show that correct amount of dark matter can be produced depending on the inflation model and the dark matter mass. In particular, we carefully evaluate the particle production rate from the transition epoch to the inflaton oscillation epoch in a realistic inflation model and point out that the gravitational particle production is efficient even if dark matter mass is much larger than the Hubble scale during inflation as long as it is smaller than the inflaton mass.
The work considers traveling wave optical solutions for the nonlinear generalized fractional KMN equation. This equation is considered for describing pulse propagation in optical fibers and ...communication systems using two quite similar approaches, based on the expansion of these solutions in the exponential or polynomial forms. Both approaches belong to the direct solving class of methods for PDEs and suppose the use of an auxiliary equation. The solutions acquired in this paper are obtained from first- and second-order differential equations that act as auxiliary equations. In addition, we generated 3D, contour, and 2D plots to illustrate the characteristics of the obtained soliton solutions. To create these plots, we carefully selected appropriate values for the relevant parameters.
SARS-CoV-2 is the underlying cause for the COVID-19 pandemic. Like most enveloped RNA viruses, SARS-CoV-2 uses a homotrimeric surface antigen to gain entry into host cells. Here we describe S-Trimer, ...a native-like trimeric subunit vaccine candidate for COVID-19 based on Trimer-Tag technology. Immunization of S-Trimer with either AS03 (oil-in-water emulsion) or CpG 1018 (TLR9 agonist) plus alum adjuvants induced high-level of neutralizing antibodies and Th1-biased cellular immune responses in animal models. Moreover, rhesus macaques immunized with adjuvanted S-Trimer were protected from SARS-CoV-2 challenge compared to vehicle controls, based on clinical observations and reduction of viral loads in lungs. Trimer-Tag may be an important platform technology for scalable production and rapid development of safe and effective subunit vaccines against current and future emerging RNA viruses.
We investigate the particle production from thermal gravitational annihilation in the very early universe, which is an important contribution for particles that might not be in thermal equilibrium ...or/and might only have gravitational interaction, such as dark matter (DM). For particles with spin 0,1/2 and 1 we calculate the relevant cross sections through gravitational annihilation and give the analytic formulas with full mass-dependent terms. We find that DM with mass between TeV and 1016 GeV could have the relic abundance that fits the observation, with small dependence on its spin. We also discuss the effects of gravitational annihilation from inflatons. Interestingly, contributions from inflatons could be dominant and have the same power dependence on Hubble parameter of inflation as that from vacuum fluctuation. Also, fermion production from inflaton, in comparison to boson, is suppressed by its mass due to helicity selection.
The recently reported result from XENON1T experiment indicates that there is an excess with 3.5σ significance in the electronic recoil events. Interpreted as new physics, new sources are needed to ...account for the electronic scattering. We show that a dark fermion ψ with mass about O(10) MeV from semi-annihilation of Z3 dark matter X and subsequent decay of a dark gauge boson Vμ may be responsible for the excess. The relevant semi-annihilation process is X+X→X‾+Vμ(→ψ+ψ‾), in which the final ψ has a box-shape energy spectrum. The fast-moving ψ can scatter with electron through an additional gauge boson that mixes with photon kinetically. The shape of the signals in this model can be consistent with the observed excess. The additional interaction with proton makes this model testable in future searches for nucleus recoil as well. Because of the lightness of invisible particle introduced, this scenario requires non-standard cosmology to accommodate the additional radiation component.
In this work, three modified multiwalled carbon nanotubes (MWCNTs) with carboxyl (MWCNT-COOH), hydroxyl (MWCNT-OH) and amino groups (MWCNT-NH), respectively, were added into the aqueous phase ...containing piperazine (PIP) to fabricate the nanocomposite nanofiltration (NF) membranes via interfacial polymerization. The influences of functional groups of MWCNTs on the performance of modified NF membrane were investigated. The MWCNTs were characterized by TEM, FT-IR and TGA; meanwhile, the properties of the membranes were evaluated by XPS, TEM, AFM and contact angle. The XPS results proved the successful incorporation of MWCNT in the active layer of modified NF membrane. When the MWCNT concentration is 0.01% (w/v), all the nanocomposite membranes possessed the optimal separation properties, among which the membrane incorporated with MWCNT-OH demonstrated the highest water flux of 41.4 L·m–2·h–1 and the Na2SO4 rejection of 97.6% whereas the one with MWCNT-COOH had the relative lowest rejection of 96.6%. Furthermore, the increased hydrophilicity of functional groups in modified MWCNTs resulted in different nodular surface morphologies, thicknesses and hydrophilicities of the nanocomposite membranes. All the membranes possessed a molecular weight cutoff (MWCO) within 300 Da and good operation stability.
We propose an ultraviolet complete theory for cold dark matter (CDM) and sterile neutrinos that can accommodate both cosmological data and neutrino oscillation experiments within 1σ level. We assume ...a new U(1)X dark gauge symmetry which is broken at ∼O(MeV) scale resulting light dark photon. Such a light mediator for DM's self-scattering and scattering-off sterile neutrinos can resolve three controversies for cold DM on small cosmological scales: cusp vs. core, too-big-to-fail and missing satellites. We can also accommodate ∼O(1) eV scale sterile neutrinos as the hot dark matter (HDM) and can fit some neutrino anomalies from neutrino oscillation experiments within 1σ. Finally, the right amount of HDM can make a sizable contribution to dark radiation, and also helps to reconcile the tension between the data on the tensor-to-scalar ratio reported by Planck and BICEP2 Collaborations.
The petrogenesis of the isolated pegmatites from granites is under debate. In the Chinese Altai, massive isolated pegmatites have been regarded as derivatives of granitic melts, which contradicts to ...the results of recent studies. In this work, the geology and mineralogy, as well as the zircon U-Pb chronology and Hf isotope geochemistry, of 10 Permian pegmatites are analyzed, and a comparative study of the Permian pegmatites and granites is conducted to reveal the petrogenesis of the Permian pegmatites in the Chinese Altai. The Permian pegmatites are concentrated in the Qiongkuer domain with a linear distribution and show structural control from regional anticlinoriums and connections to adjacent migmatites and luecogranite dykes. Their zircon U-Pb ages are 274–253 Ma, with the dominating age being late Permian. The pegmatites have three mineralization types including Li-Be-Ta-Nb ± Sn, Be-Nb-Ta ± REEs (rare earth elements) and REEs. The former two are comparable with the Triassic and Devonian-Carboniferous pegmatites in mineralization and Hf isotope composition, respectively, and the latter is unique in the Permian generation. The Permian pegmatites have comparable Hf isotope compositions with the juvenile and specific components in the Habahe Group, which indicates the dependency of mineralization on source from the heterogeneous Habahe Group metasedimentary rocks. The pegmatites also show decoupling spatial-temporal and differentiation-source correlations with the Permian granites, indicating no genetic relationship between them. Combining with the Permian high temperature metamorphism and previous tectonic-magmatic-metamorphic studies, we suggest that the Permian rare metal/earth pegmatites were likely generated by anatexis of the Habahe Group metasedimentary rocks under an extensional setting after the arc-arc collision between the Junggar arcs and the Chinese Altai.
•The Permian pegmatites in the Chinese Altai formed mainly during late Permian.•The pegmatites have three mineralization types including Li-Be-Ta-Nb ± Sn, Be-Nb-Ta ± REEs and REEs.•The mineralization types of the pegmatites show dependencies on source and partial meting degrees of source.•The pegmatites show decoupling spatial-temporal-differentiation-source correlations to the Permian granites.•The pegmatites were likely generated by anatexis of metasedimentary rocks after arc-arc collision.
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