1,267 research outputs found
Method for producing heat-resistant semi-inorganic compounds
The method for producing a heat resistant, semi-inorganic compound is discussed. Five examples in which various alcohols, phenols, and aromatic carbonic acids are used to test heat resistance and solubility are provided
Organometalic carbosilane polymers containing vanadium and their preparation
The present invention concerns a new organometallic polymer material containing in part a vanadium-siloxane linkage (V-0-Si), which has excellent resistance to heat and oxidation and a high residue ratio after high temperature treatment in a non-oxidizing atmosphere, for example, nitrogen, argon, helium, ammonia, or hydrogen
Induction of Apoptosis by PQ1, a Gap Junction Enhancer that Upregulates Connexin 43 and Activates the MAPK Signaling Pathway in Mammary Carcinoma Cells
Citation: Shishido, S. N., & Nguyen, T. A. (2016). Induction of Apoptosis by PQ1, a Gap Junction Enhancer that Upregulates Connexin 43 and Activates the MAPK Signaling Pathway in Mammary Carcinoma Cells. International Journal of Molecular Sciences, 17(2), 19. doi:10.3390/ijms17020178The mechanism of gap junction enhancer (PQ1) induced cytotoxicity is thought to be attributed to the change in connexin 43 (Cx43) expression; therefore, the effects of Cx43 modulation in cell survival were investigated in mammary carcinoma cells (FMC2u) derived from a malignant neoplasm of a female FVB/N-Tg(MMTV-PyVT)634Mul/J (PyVT) transgenic mouse. PQ1 was determined to have an IC50 of 6.5 mu M in FMC2u cells, while inducing an upregulation in Cx43 expression. The effects of Cx43 modulation in FMC2u cell survival was determined through transfection experiments with Cx43 cDNA, which induced an elevated level of protein expression similar to that seen with PQ1 exposure, or siRNA to silence Cx43 protein expression. Overexpression or silencing of Cx43 led to a reduction or an increase in cell viability, respectively. The mitogen-activated protein kinase (MAPK) family has been implicated in the regulation of cell survival and cell death; therefore, the gap junctional intercellular communication (GJIC)-independent function of PQ1 and Cx43 in the Raf/Mitogen-activated protein kinase/ERK kinase/extracellular-signal-regulated kinase (Raf-MEK-ERK) cascade of cellular survival and p38 MAPK-dependent pathway of apoptosis were explored. PQ1 treatment activated p44/42 MAPK, while the overexpression of Cx43 resulted in a reduced expression. This suggests that PQ1 affects the Raf-MEK-ERK cascade independent of Cx43 upregulation. Both overexpression of Cx43 and PQ1 treatment stimulated an increase in the phosphorylated form of p38-MAPK, reduced levels of the anti-apoptotic protein Bcl-2, and increased the cleavage of pro-caspase-3. Silencing of Cx43 protein expression led to a reduction in the phosphorylation of p38-MAPK and an increase in Bcl-2 expression. The mechanism behind PQ1-induced cytotoxicity in FMC2u mammary carcinoma cells is thought to be attributed to the change in Cx43 expression. Furthermore, PQ1-induced apoptosis through the upregulation of Cx43 may depend on p38 MAPK, highlighting that the effect of PQ1 on gap junctions as well as cellular survival via a MAPK-dependent pathway
^{115}In-NQR evidence for unconventional superconductivity in CeIn_3 under pressure
We report evidence for unconventional superconductivity in CeIn_3 at a
pressure P = 2.65 GPa above critical pressure (P_c ~ 2.5 GPa) revealed by the
measurements of nuclear-spin-lattice-relaxation time (T_1) and
ac-susceptibility (ac-chi). Both the measurements of T_1 and ac-chi have
pointed to a superconducting transition at T_c = 95 mK, which is much lower
than an onset temperature T_{onset} = 0.15 K at zero resistance. The
temperature dependence of 1/T_1 shows no coherence peak just below T_c,
indicative of an unconventional nature for the superconductivity induced in
CeIn_3.Comment: 4 pages, 4 figures, to be published in Phys.Rev.
Novel phase diagram for antiferromagnetism and superconductivity in pressure-induced heavy-fermion superconductor CeRhIn probed by In-NQR
We present a novel phase diagram for the antiferromagnetism and
superconductivity in CeRhIn probed by In-NQR studies under pressure
(). The quasi-2D character of antiferromagnetic spin fluctuations in the
paramagnetic state at = 0 evolves into a 3D character because of the
suppression of antiferromagnetic order for 1.36 GPa (QCP:
antiferromagnetic quantum critical point). Nuclear-spin-lattice-relaxation rate
measurements revealed that the superconducting order occurs in the
range 1.36 -- 1.84 GPa, with maximum 0.9 K around
1.36 GPa.Comment: 5 pages, 5 figures, submitted to PR
Thermoelectric response near a quantum critical point: the case of CeCoIn5
We present a study of thermoelectric coefficients in CeCoIn_5 down to 0.1 K
and up to 16 T in order to probe the thermoelectric signatures of quantum
criticality. In the vicinity of the field-induced quantum critical point, the
Nernst coefficient nu exhibits a dramatic enhancement without saturation down
to lowest measured temperature. The dimensionless ratio of Seebeck coefficient
to electronic specific heat shows a minimum at a temperature close to threshold
of the quasiparticle formation. Close to T_c(H), in the vortex-liquid state,
the Nernst coefficient behaves anomalously in puzzling contrast with other
superconductors and standard vortex dynamics.Comment: 4 pages, 4 figures,final published versio
Unconventional superconductivity and antiferromagnetic quantum critical behavior in the isovalent-doped BaFe2(As1-xPx)2
Spin dynamics evolution of BaFe(AsP) was probed as a
function of P concentration via P NMR. Our NMR study reveals that
two-dimensional antiferromagnetic (AF) fluctuations are notably enhanced with
little change in static susceptibility on approaching the AF phase from the
superconducting dome. Moreover, magnetically ordered temperature
deduced from the relaxation rate vanishes at optimal doping. These results
provide clear-cut evidence for a quantum-critical point (QCP), suggesting that
the AF fluctuations associated with the QCP play a central role in the
high- superconductivity.Comment: 5 pages, 3 figure
Strong suppression of superconductivity by divalent Ytterbium Kondo-holes in CeCoIn_5
To study the nature of partially substituted Yb-ions in a Ce-based Kondo
lattice, we fabricated high quality Ce_{1-x}Yb_xCoIn_5 epitaxial thin films
using molecular beam epitaxy. We find that the Yb-substitution leads to a
linear decrease of the unit cell volume, indicating that Yb-ions are divalent
forming Kondo-holes in Ce_{1-x}Yb_xCoIn_5, and leads to a strong suppression of
the superconductivity and Kondo coherence. These results, combined with the
measurements of Hall effect, indicate that Yb-ions act as nonmagnetic impurity
scatters in the coherent Kondo lattice without serious suppression of the
antiferromagnetic fluctuations. These are in stark contrast to previous studies
performed using bulk single crystals, which claim the importance of valence
fluctuations of Yb-ions. The present work also highlights the suitability of
epitaxial films in the study of the impurity effect on the Kondo lattice.Comment: 5 pages, 4 figure
Competition between unconventional superconductivity and incommensurate antiferromagnetic order in CeRh1-xCoxIn5
Elastic neutron diffraction measurements were performed on the quasi-two
dimensional heavy fermion system CeRh1-xCoxIn5, ranging from an incommensurate
antiferromagnet for low x to an unconventional superconductor on the Co-rich
end of the phase diagram. We found that the superconductivity competes with the
incommensurate antiferromagnetic (AFM) order characterized by qI=(1/2, 1/2,
delta) with delta=0.298, while it coexists with the commensurate AFM order with
qc=(1/2, 1/2, 1/2). This is in sharp contrast to the CeRh1-xIrxIn5 system,
where both the commensurate and incommensurate magnetic orders coexist with the
superconductivity. These results reveal that particular areas on the Fermi
surface nested by qI play an active role in forming the superconducting state
in CeCoIn5.Comment: RevTeX4, 4 pages, 4 eps figures; corrected a typo and a referenc
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