1,044 research outputs found
Microsatellite and mitochondrial DNA analysis of the genetic structure of Chinese horseshoe crab (Tachypleus tridentatus) in southeast China coast
Chinese horseshoe crab (Tachypleus tridentatus) is a Xiphosura animal of significant commercial importance and in danger of extinction in China. To better estimate how genetic structure can be used to obtain a conservation perspective of the species, genetic variation was examined in nine locations covering its distributing range in the coast of Chinese mainland using ten nuclear microsatellite DNA loci and mitochondrial DNA control region (CR) sequences. Moderate levels of genetic diversity were detected (expected heterozygosity from microsatellites was 0.635, haplotype diversity from mitochondrial DNA was 0.800) as a whole. Significant genetic differentiation was detected only by mitochondrial DNA (FST = 0.0693, P < 0.01), while microsatellite markers indicated nuclear genetic homogeneity of these locations. Probably, nuclear genetic homogeneity was caused by outbreeding among different groups due to artificial transporting. Very weak genetic differentiation indicates that reintroduction programs of the movement and mixing of horseshoe crab from different locations will result in minimal negative genetic effects. Upon four management units were inferred from the results of CR analysis, accordingly four or more nature reserves should be established to conserve this endangered animal along the Chinese coast. Haplotype network pattern indicated that T. tridentatus population in Chinese coast has undergone historic population expansion and very recent historic population recession. Mismatch distributions analysis also revealed existence of historic demographic expansion.Keywords: Tachypleus tridentatus, microsatellites, mitochondrial DNA, population structure, genetic diversityAfrican Journal of Biotechnology Vol. 12(16), pp. 2088-209
TBG V: Exact Analytic Many-Body Excitations In Twisted Bilayer Graphene Coulomb Hamiltonians: Charge Gap, Goldstone Modes and Absence of Cooper Pairing
We find exact analytic expressions for the energies and wavefunctions of the
charged and neutral excitations above the exact ground states (at rational
filling per unit cell) of projected Coulomb Hamiltonians in twisted bilayer
graphene. Our exact expressions are valid for any form of the Coulomb
interaction and any form of and tunneling. The single charge
excitation energy is a convolution of the Coulomb potential with a quantum
geometric tensor of the TBG bands. The neutral excitations are (high-symmetry
group) magnons, and their dispersion is analytically calculated in terms of the
form factors of the active bands in TBG. The two-charge excitation energy and
wavefunctions are also obtained, and a sufficient condition on the graphene
eigenstates for obtaining a Cooper-pair from Coulomb interactions is obtained.
For the actual TBG bands at the first magic angle, we can analytically show
that the Cooper pair binding energy is zero in all such projected Coulomb
models, implying that either phonons and/or non-zero kinetic energy are needed
for superconductivity. Since the [Phys. Rev. Lett. 122, 246401] showed that the
kinetic energy bounds on the superexchange energy are less in Coulomb
units, the phonon mechanism becomes then very likely. If nonetheless the
superconductivity is due to kinetic terms which render the bands non-flat, one
prediction of our theory is that the highest would not occur at the
highest DOS.Comment: references adde
TBG VI: An Exact Diagonalization Study of Twisted Bilayer Graphene at Non-Zero Integer Fillings
Using exact diagonalization, we study the projected Hamiltonian with Coulomb
interaction in the 8 flat bands of first magic angle twisted bilayer graphene.
Employing the U(4) (U(4)U(4)) symmetries in the nonchiral (chiral) flat
band limit, we reduced the Hilbert space to an extent which allows for study
around fillings. In the first chiral limit
where () is the () stacking hopping, we find that the
ground-states at these fillings are extremely well-described by Slater
determinants in a so-called Chern basis, and the exactly solvable charge
excitations found in [arXiv:2009.14200] are the lowest charge excitations up to
system sizes (for restricted Hilbert space) in the chiral-flat
limit. We also find that the Flat Metric Condition (FMC) used in
[arXiv:2009.11301,2009.11872,2009.12376,2009.13530,2009.14200] for obtaining a
series of exact ground-states and excitations holds in a large parameter space.
For , the ground state is the spin and valley polarized Chern insulator
with at (0.3) with (without) FMC. At
, we can only numerically access the valley polarized sector, and we
find a spin ferromagnetic phase when where is
the factor of rescaling of the actual TBG bandwidth, and a spin singlet phase
otherwise, confirming the perturbative calculation [arXiv:2009.13530]. The
analytic FMC ground state is, however, predicted in the intervalley coherent
sector which we cannot access [arXiv:2009.13530]. For with/without
FMC, when is large, the finite-size gap to the neutral
excitations vanishes, leading to phase transitions. Further analysis of the
ground state momentum sectors at suggests a competition among
(nematic) metal, momentum () stripe and -CDW orders at large
.Comment: 21+23 pages, 13+15 figure
Enchanced levels of apolipoprotein M during HBV infection feedback suppresses HBV replication
<p>Abstract</p> <p>Background</p> <p>Chronic liver diseases can interfere with hepatic metabolism of lipoproteins, apolipoproteins. Hepatitis B virus (HBV) is a major etiological agent causing acute and chronic liver diseases. Apolipoprotein M (ApoM) is a high-density lipoprotein (HDL) apolipoprotein and exclusively expressed in the liver parenchyma cells and in the tubular cells of the kidney. This study was to determine the correlation between HBV infection and ApoM expression.</p> <p>Materials and methods</p> <p>Serum ApoM levels in patients with HBV infection and in healthy individuals were measured by ELISA, ApoM mRNA expression were determined by RT-PCR, and the expression of S and E proteins of HBV, as well as the synthesis of viral DNA were measured by ELISA and real-time PCR.</p> <p>Results</p> <p>The levels of serum ApoM was significantly elevated in patients as compared to healthy individuals (<it>P </it>< 0.001), ApoM promoter activity, mRNA and protein expression were all stimulated in cells transfected with infectious HBV clone. In addition, ApoM decreases the expression of S and E proteins of HBV and the synthesis of viral DNA.</p> <p>Conclusion</p> <p>Raised ApoM levels in HBV infection may in turn suppress HBV replication, one of the protective mechanisms of nature.</p
2,3:6,7-Bis(methylenedioxy)phenanthrene
In the title molecule, C16H10O4, all the non-H atoms are coplanar. The crystal structure is stabilized by weak intermolecular C—H⋯O contacts and π–π stacking interactions (the interplanar distance is 3.43 Å)
1-[Bicyclo[4.2.0]octa-1(6),2,4-trien-3-yl]-3-[bicyclo[4.2.0]octa-1(6),2,4-trien-3-ylmethyl]imidazolium hexafluorophosphate
In the title compound, C20H19N2
+·PF6
−, the two benzocyclobutene units are essentially planar and they form dihedral angles of 38.0 (2) and 72.7 (2)°, with the central imidazolium ring. In the crystal structure, weak C—H⋯π and π-–π stacking interactions [centroid–centroid distance = 3.742 (2) Å] contribute to the stability of the crystal structure. The PF6
− ion is disordered over two positions with site occupancies of 0.869 (9) and 0.131 (9)
Bloch surface plasmon enhanced blue emission from InGaN/GaN light-emitting diode structures with Al-coated GaN nanorods
InGaN/GaN light-emitting diode structures with Al-coated GaN nanorods were fabricated by using soft ultraviolet nanoimprint lithography. The intensity of light emission was found to be greatly enhanced due to the strong near-fields confined at the interface of Al/GaN and extended to the multiple quantum wells (MQWs) active region. The dynamics of carrier recombination and plasmon-enhanced Raman scattering were also investigated, providing a progressive view on the effective energy transfer between MQWs and surface plasmons.This work was supported by Special Funds for Major State
Basic Research Project (Nos. 2011CB301900 and
2012CB619304), the Hi-tech Research Project (No.
2014AA032605), National Nature Science Foundation of
China (Nos. 11104130, 61274003, 60990311, 61176063, and
61422401), the Program for New Century Excellent Talents
in University (No. NCET-11-0229), Nature Science Foundation
of Jiangsu Province (Nos. BK2011556, BK2011010,
BK2010385, BY2013077, and BE2011132), Funds of Key
Laboratory (No. 9140C140102120C14), Scientific Innovation
Research of College Graduate in Jiangsu Province
(CXZZ12_0052), PAPD, the Fundamental Research Funds
for the Central Universities, the Research Funds from NJUYangzhou
Institute of Opto-electronics, and the Australian
Research Council Discovery Early Career Researcher Award
(DE130101700)
Superconductivity induced by oxygen deficiency in Sr-doped LaOFeAs
We synthesized Sr-doped sample with single phase,
and systematically studied the effect of oxygen deficiency in the Sr-doped
LaOFeAs system. It is found that substitution of Sr for La indeed induces the
hole carrier evidenced by positive thermoelectric power (TEP), but no bulk
superconductivity is observed. The superconductivity can be realized by
annealing the as-grown sample in vacuum to produce the oxygen deficiency. With
increasing the oxygen deficiency, the superconducting transition temperature
() increases and maximum reaches about 26 K the same as that in
La(O,F)FeAs. TEP dramatically changes from positive to negative in the
nonsuperconducting as-grown sample to the superconducting samples with oxygen
deficiency. While is always negative for all samples (even for Sr-doped
as grown sample). It suggests that the is
still electron-type superconductor.Comment: 4 pages, 4 figure
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