2,379 research outputs found
Unveiling Hidden Physics in the 215-Kelvin Superconducting Calcium Hydride: Temperature, Quantum and Defect Effects
Temperature and quantum effects induce the structural complexity of condensed
hydrogen, and therefore they are expected to impact nontrivially the structures
of clathrate hydrides. Exemplified by clathrate calcium hydride, we show
through ab initio (path-integral) molecular dynamics simulations that these
effects are indeed pivotal at 100-200 GPa. The quantum equation of states
derived at 300 K suggests that the synthesized samples in previous experiments
were berthollide-like CaH, with the stoichiometric defect
increasing smoothly during decompression. The change of composition provides an
explanation for the experimental observation of positive pressure dependence of
superconducting T below 165 GPa. Furthermore, we find significant proton
diffusion in CaH at 150-300 K, with the diffusion coefficient
reaching 10 cm/s. This suggests a coexistence of superconductivity
and proton diffusion in clathrate hydrides. Our findings underline the
importance of temperature, quantum and defect effects to the understandings of
the structure and pertinent physics in high-T superconducting clathrate
hydrides.Comment: 9 pages, 3 figure
Virus efficacy of recombined Autographa californica M nucleopolyhedrovirus (AcMNPV) on tea pest Ectropis obliqua
Ectropis obliqua is a major tea pest and chitin synthase (CHS) plays a key role in the pest growth and development. A 192 bp conserved domain from E. obliqua CHS gene was cloned and it was used to construct recombined Autographa californica M nucleopolyhedrovirus (AcMNPV) with double-stranded RNA interference (dsRNAi) method. The recombined AcMNPV virus could propagate in host cells sf9. Injection test showed that the virus efficacy of the recombined AcMNPV on E. obliqua larvae was significantly enhanced. It is considered that the CHS dsRNAi mediated by the nuclear polyhedrosis virus will be interesting for development of alternative bio-pesticide to control the tea pest E. obliqua.Keywords: Chitin synthase, baculovirus, double-stranded RNA interference, Ectropis obliquaAfrican Journal of Biotechnology Vol. 9(33), pp. 5412-5418, 16 August, 201
Quantum Interference Effects in Molecular Y- and Rhomb-Type Systems
In this paper we report the first observation of molecular population trapping in four level systems. Constructive and destructive quantum interferences between two sum-frequncy two-photon transitions in Y- and rhomb-type four-level systems, respectively, im sodium molecules have been experimentally achieved by using only one laser source. Their energy level schemes are featured by the extremely near-resonant enhancement of the equal-frequency two-photon transitions, sharing both the initial and the intermediate levels for the Y-type, and sharing both the initial and the final levels for the rhomb-type systems. Their novel spectral effects are to show seriously restrained Doppler-free UV peak at the nominal location of the induced two-photon transition with visible fluorescence in rhomb-type schems, and to show a strong extra UV peak but null visible fluorescence in the middle between the two dipole allowed two-photon transitions
Observing white dwarf tidal stripping with TianQin gravitational wave observatory
Recently discovered regular X-ray bursts known as quasi-periodic eruptions
have a proposed model that suggests a tidal stripping white dwarf inspiralling
into the galaxy's central black hole on an eccentric orbit. According to this
model, the interaction of the stripping white dwarf with the central black hole
would emit gravitational wave signals as well, their detection can help explore
the formation mechanism of quasi-periodic eruptions and facilitate
multi-messenger observations. In this paper, we aim to perform a preliminary
study of the gravitation wave observation of TianQin on this stripping white
dwarf model. We investigated the horizon distance of TianQin on this type of
gravitation wave signal and found it can be set to 200Mpc. We also find that
those stripping white dwarf model sources with central black hole mass within
are more likely to be detected by TianQin. We
assessed the parameter estimation precision of TianQin on those stripping white
dwarf model sources. Our result shows that, even in the worst case, TianQin can
determine the central black hole mass, the white dwarf mass, the central black
hole spin, and the orbital initial eccentricity with a precision of .
In the optimistic case, TianQin can determine the central black hole mass and
the white dwarf mass with a precision of , determine the central black
hole spin with a precision of , and determine the orbital initial
eccentricity with a precision of . Moreover, TianQin can determine the
luminosity distance with a precision of and determine the sky
localization with a precision of .Comment: 9 pages, 4 figure
Thymopentin (TP5), an immunomodulatory peptide, suppresses proliferation and induces differentiation in HL-60 cells
AbstractThymopentin (Arg–Lys–Asp–Val–Tyr, TP5) has shown immuno-regulatory activities in humans. In the present study, we investigated the effects of TP5 on the proliferation and differentiation of a human promyelocyte leukemia cell line, HL-60. It is noteworthy that TP5 displayed concentration-dependent inhibitory effects on the proliferation and colony formation of HL-60 cells. Furthermore, the decrease or even disappearance of AgNORs from nucleoli was observed in HL-60 cells after the treatment with TP5. The suppression induced by TP5 was accompanied by an accumulation of cell cycle in the G0/G1 phase. Moreover, TP5 significantly increased the NBT-reduction activity of HL-60 cells. Cytofluorometric and morphologic analysis indicated that TP5 had induced differentiation along the granulocytes lineage in HL-60 cells. d-tubocurarine (TUB) significantly antagonized the inhibitory effects induced by TP5, whereas atropine did not exhibit such effect. All the results indicated that TP5 was able to significantly inhibit proliferation and induce differentiation in HL-60 cells. Our observations also implied that TP5 not only acted as an immunomodulatory factor in cancer chemotherapy, but is also a potential chemotherapeutic agent in the human leukemia therapy
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