Superconductivity in the PbO-type structure α-FeSe Hsu, Fong-Chi; Luo, Jiu-Yong; Yeh, Kuo-Wei ...
Proceedings of the National Academy of Sciences - PNAS,
09/2008, Letnik:
105, Številka:
38
Journal Article
Recenzirano
Odprti dostop
The recent discovery of superconductivity with relatively high transition temperature (Tc) in the layered iron-based quaternary oxypnictides LaO₁₋xFx FeAs by Kamihara et al. Kamihara Y, Watanabe T, ...Hirano M, Hosono H (2008) Iron-based layered superconductor LaO1-xFx FeAs (x = 0.05-0.12) with Tc = 26 K. J Am Chem Soc 130:3296-3297. was a real surprise and has generated tremendous interest. Although superconductivity exists in alloy that contains the element Fe, LaOMPn (with M = Fe, Ni; and Pn = P and As) is the first system where Fe plays the key role to the occurrence of superconductivity. LaOMPn has a layered crystal structure with an Fe-based plane. It is quite natural to search whether there exists other Fe based planar compounds that exhibit superconductivity. Here, we report the observation of superconductivity with zero-resistance transition temperature at 8 K in the PbO-type α-FeSe compound. A key observation is that the clean superconducting phase exists only in those samples prepared with intentional Se deficiency. FeSe, compared with LaOFeAs, is less toxic and much easier to handle. What is truly striking is that this compound has the same, perhaps simpler, planar crystal sublattice as the layered oxypnictides. Therefore, this result provides an opportunity to better understand the underlying mechanism of superconductivity in this class of unconventional superconductors.
Polyphenol resveratrol (RSV) has been associated with Silent Information Regulator T1 (SIRT1) and AMP‐activated protein kinase (AMPK) metabolic stress sensors and probably responds to the ...intracellular energy status. Our aim here was to investigate the neuroprotective effects of RSV and its association with SIRT1 and AMPK signaling in recurrent ischemia models. In this study, elderly male Wistar rats received a combination of two mild transient middle cerebral artery occlusions (tMCAOs) as an in vivo recurrent ischemic model. Primary cultured cortical neuronal cells subjected to combined oxygen–glucose deprivation (OGD) were used as an in vitro recurrent ischemic model. RSV administration significantly reduced infarct volumes, improved behavioral deficits and protected neuronal cells from cell death in recurrent ischemic stroke models in vivo and in vitro. RSV treatments significantly increased the intracellular NAD+/NADH ratio, AMPK and SIRT1 activities, decreased energy assumption and restored cell energy ATP level. SIRT1 and AMPK inhibitors and specific small interfering RNA (siRNA) for SIRT1 and AMPK significantly abrogated the neuroprotection induced by RSV. AMPK‐siRNA and inhibitor decreased SIRT1 activities; however, SIRT1‐siRNA and inhibitor had no impact on phospho‐AMPK (p‐AMPK) levels. These results indicated that the neuroprotective effects of RSV increased the intracellular NAD+/NADH ratio as well as AMPK and SIRT1 activities, thereby reducing energy ATP requirements during ischemia. SIRT1 is a downstream target of p‐AMPK signaling induced by RSV in the recurrent ischemic stroke model.
Resveratrol (RSV) administration significantly reduced infarct volumes, improved behavioral, increased AMPK and SIRT1activities and decreased energy assumption and restored cell energy ATP level in recurrent ischemic stroke models. RSV provides neuroprotection in recurrent stroke models by regulating the AMPK and SIRT1 signaling thereby reducing energy requirements during ischemia.
Superconducting FeSe thin films were prepared at a substrate temperature of 320
°C by pulsed laser deposition. X-ray diffraction and transmission electron microscopic analyses showed that highly
...c-axis-orientated and high-quality films were obtained on various substrate materials, including single-crystal MgO, LaAlO
3, SrTiO
3 and (100)-Si, and amorphous-SiO
x, at such low temperature. From transport measurements all the films showed low-temperature structural phase transition at ∼
60–90
K and superconducting transition at onset temperature varies from ∼
7
K to <
2
K, depending on the substrate used. The transport property of FeSe film on Si was found most different from all the others, in spite of their similarity in structural analysis. Chemical analysis demonstrated that Fe and Se homogeneously distributed in the film and the stoichiometry of FeSe and the bonding states of Fe and Se are as well uniform along the film growth direction.
In this study we demonstrate a new composite oxide thin films of (MoO
3)
1
−
x
(V
2O
5)
x, x
=
0, 0.01, 0.03, and 0.05, fabricated by pulsed laser deposition (PLD). The performance of platinum (Pt) ...catalyst activated hydrogen gas sensor with modified (MoO
3)
1
−
x
(V
2O
5)
x thin films were investigated. The thickness of the (MoO
3)
1
−
x
(V
2O
5)
x thin film is about 600–650
nm and its surface has a uniform morphology. Our results show that the gasochromic sensors prepared by (MoO
3)
0.99(V
2O
5)
0.01 thin film exhibited excellent hydrogen sensibility. The response and recovery time are in the range of 9–15
min for coloration and bleaching at room temperature under H
2 atmosphere. The results also show that (MoO
3)
1
−
x
(V
2O
5)
x/Pt (x
=
0.01, 0.03, 0.05) thin films perform better gasochromic capability than the pristine MoO
3/Pt sample.
Abstract
Polyphenol resveratrol (
RSV
) has been associated with
S
ilent
I
nformation
R
egulator
T
1 (
SIRT
1) and
AMP
‐activated protein kinase (
AMPK
) metabolic stress sensors and probably ...responds to the intracellular energy status. Our aim here was to investigate the neuroprotective effects of
RSV
and its association with
SIRT
1 and
AMPK
signaling in recurrent ischemia models. In this study, elderly male
W
istar rats received a combination of two mild transient middle cerebral artery occlusions (
tMCAO
s) as an
in vivo
recurrent ischemic model. Primary cultured cortical neuronal cells subjected to combined oxygen–glucose deprivation (
OGD
) were used as an
in vitro
recurrent ischemic model.
RSV
administration significantly reduced infarct volumes, improved behavioral deficits and protected neuronal cells from cell death in recurrent ischemic stroke models
in vivo
and
in vitro
.
RSV
treatments significantly increased the intracellular
NAD
+
/
NADH
ratio,
AMPK
and
SIRT
1 activities, decreased energy assumption and restored cell energy
ATP
level.
SIRT
1 and
AMPK
inhibitors and specific small interfering
RNA
(si
RNA
) for
SIRT
1 and
AMPK
significantly abrogated the neuroprotection induced by
RSV
.
AMPK
‐si
RNA
and inhibitor decreased
SIRT
1 activities; however,
SIRT
1‐si
RNA
and inhibitor had no impact on phospho‐
AMPK
(p‐
AMPK
) levels. These results indicated that the neuroprotective effects of RSV increased the intracellular
NAD
+
/
NADH
ratio as well as
AMPK
and
SIRT
1 activities, thereby reducing energy
ATP
requirements during ischemia.
SIRT
1 is a downstream target of p‐
AMPK
signaling induced by
RSV
in the recurrent ischemic stroke model.
PRKAG2 cardiac syndrome is an autosomal dominant inherited disease resulted from mutations in the PRK- AG2 gene that encodes γ2 regulatory subunit of AMP-activated protein kinase. Affected patients ...usually develop ventricular tachyarrhythmia and experience progressive heart failure that is refractory to medical treatment and requires cardiac transplantation. In this study, we identify a H530R mutation in PRKAG2 from patients with familial Wolff-Parkinson-White syndrome. By generating H530R PRKAG2 transgenic and knock-in mice, we show that both models recapitulate human symptoms including cardiac hypertrophy and glycogen storage, confirming that the H530R mutation is causally related to PRKAG2 cardiac syndrome. We further combine adeno-associated virus-9 （AAV9） and the CRISPR/Cas9 gene-editing system to disrupt the mutant PRKAG2 allele encoding H530R while leav- ing the wild-type allele intact. A single systemic injection of AAV9-Cas9/sgRNA at postnatal day 4 or day 42 substantially restores the morphology and function of the heart in H530R PRKAG2 transgenic and knock-in mice. Together, our work suggests that in vivo CRISPR/Cas9 genome editing is an effective tool in the treatment of PRKAG2 cardiac syndrome and other dominant inherited cardiac diseases by selectively disrupting disease-causing mutations.
In order to protect carboniferous system layer in east Sichuan, it added microparticle filling agent in drilling fluid. It depended on the physical truth and principle of protecting hydrocarbon ...reservoir technology which used in drilling fluid. According to the property of filling agent, it studied fluid loss control agent CKH-1, calcium carbonate superfine powder, non-permeate pressure-bearing agent CY-1 and nanometer material. Dosage of CKH-1 was 1%, calcium carbonate superfine powder was 2%, CY-1 was 4% and nanometer material was 1% ,which were firmed via experiment of viscosity and fluid loss control. Microparticle filling agent was sequentially formed.
In this study we demonstrate a new composite oxide thin films of (MoO3)1a degree x(V2O5)x, x=0, 0.01, 0.03, and 0.05, fabricated by pulsed laser deposition (PLD). The performance of platinum (Pt) ...catalyst activated hydrogen gas sensor with modified (MoO3)1a degree x(V2O5)x thin films were investigated. The thickness of the (MoO3)1a degree x(V2O5)x thin film is about 600-650nm and its surface has a uniform morphology. Our results show that the gasochromic sensors prepared by (MoO3)0.99(V2O5)0.01 thin film exhibited excellent hydrogen sensibility. The response and recovery time are in the range of 9-15min for coloration and bleaching at room temperature under H2 atmosphere. The results also show that (MoO3)1a degree x(V2O5)x/Pt (x=0.01, 0.03, 0.05) thin films perform better gasochromic capability than the pristine MoO3/Pt sample.
The recent discovery of superconductivity with relatively high transition temperature (Tc) in the layered iron-based quaternary oxypnictides La... FeAs by Kamihara et al. Kamihara Y, Watanabe T, ...Hirano M, Hosono H (2008) Iron-based layered superconductor LaO1-xFx FeAs (x = 0.05-0.12) with Tc = 26 K. J Am Chem Soc 130:3296-3297. was a real surprise and has generated tremendous interest. Although superconductivity exists in alloy that contains the element Fe, LaOMPn (with M = Fe, Ni; and Pn = P and As) is the first system where Fe plays the key role to the occurrence of superconductivity. LaOMPn has a layered crystal structure with an Fe-based plane. It is quite natural to search whether there exists other Fe based planar compounds that exhibit superconductivity. Here, we report the observation of superconductivity with zero-resistance transition temperature at 8 K in the PbO-type α-FeSe compound. A key observation is that the clean superconducting phase exists only in those samples prepared with intentional Se deficiency. FeSe, compared with LaOFeAs, is less toxic and much easier to handle. What is truly striking is that this compound has the same, perhaps simpler, planar crystal sublattice as the layered oxypnictides. Therefore, this result provides an opportunity to better understand the underlying mechanism of superconductivity in this class of unconventional superconductors. (ProQuest: ... denotes formulae/symbols omitted.)
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