The mechanism of superconductivity in cuprates remains one of the big challenges of condensed matter physics. High-Tc
cuprates crystallize into a layered perovskite structure featuring copper oxygen ...octahedral coordination. Due to the Jahn Teller effect in combination with the strong static Coulomb interaction, the octahedra in high-Tc
cuprates are elongated along the c axis, leading to a 3dx²-y² orbital at the top of the band structure wherein the doped holes reside. This scenario gives rise to 2D characteristics in high-Tc
cuprates that favor d-wave pairing symmetry. Here, we report superconductivity in a cuprate Ba₂CuO4-y, wherein the local octahedron is in a very exceptional compressed version. The Ba₂CuO4-y compound was synthesized at high pressure at high temperatures and shows bulk superconductivity with critical temperature (Tc
) above 70 K at ambient conditions. This superconducting transition temperature is more than 30 K higher than the Tc
for the isostructural counterparts based on classical La₂CuO₄. X-ray absorption measurements indicate the heavily doped nature of the Ba₂CuO4-y superconductor. In compressed octahedron, the 3d3z²-r² orbital will be lifted above the 3dx²-y² orbital, leading to significant 3D nature in addition to the conventional 3dx²-y² orbital. This work sheds important light on advancing our comprehensive understanding of the superconducting mechanism of high Tc
in cuprate materials.
Abstract Diabetes mellitus (DM) adversely affects the number and function of circulating endothelial progenitor cells (EPCs). Consequently, there is also a reduction in the repair mechanism of these ...cells, which is a critical and initiating factor in the development of diabetic vascular disease. The aim of the present study was to analyze miR expression profiles in EPCs from patients with DM and choose the most significantly regulated miR to study its possible role on EPC dysfunction and elucidate its mechanism of action. EPCs were collected from subjects with Type II DM and non-diabetic control subjects. Total RNA was harvested from EPCs, and a total of 5 candidate miRNAs were identified by microarray screening and were quantified by TaqMan real-time PCR. Lentiviral vectors expressing miR-126 and miR-126 inhibitor (anti-miR-126) were transfected into EPCs, and the EPC colony-forming capacity, proliferation activity, migratory activity, differentiation capacity, and apoptotic susceptibility were determined and Western Blotting and mRNA real-time PCR analyses were performed. To study the mechanisms, lentiviral vectors expressing Spred-1 and a short interfering RNA (siRNA) targeting Spred-1 were prepared. Five miRs were aberrantly downregulated in EPCs from DM patients. These miRs included miR-126, miR-21, miR-27a, miR-27b and miR-130a. Anti-miR-126 inhibited EPC proliferation, migration, and enhanced apoptosis. Restored miR-126 expression in EPCs from DM promoted EPC proliferation, migration, and inhibited EPC apoptosis ability. Despite this, miR-126 had no effect on EPC differentiation. miR-126 overexpression significantly downregulated Spred-1 in EPCs. The knockdown of Spred-1 expression in EPCs from DM promoted proliferation, migration, and inhibited apoptosis of the cells. The signal pathway of miR-126 effecting on EPCs is partially mediated through Ras/ERK/VEGF and PI3K/Akt/eNOS regulation. This study provides the first evidence that miR-126 is downregulated in EPCs from diabetic patients, and impairs EPCs-mediated function via its target, Spred-1, and through Ras/ERK/VEGF and PI3K/Akt/eNOS signal pathway.
All-metallic corrugate core sandwich panels as primary loading structures may rapidly soften under compressive loading due mainly to core member buckling once the peak compressive stress is reached, ...resulting in reduced load-carrying capability. Inserting close-celled aluminum foam into the corrugate core has been envisioned as a feasible way to enhance the load capacity. The enhancement due to foam filling were firstly explored experimentally under quasi-static out-of-plane compression and the underlying mechanisms subsequently numerically studied using finite element simulations. The foam filled corrugated panel was found to have strength and energy absorption much greater than the sum of those of an empty corrugated sandwich panel and the aluminum foam alone. It was demonstrated that the core members in the foam-filled panel were considerably stabilized by the filling foam against lateral deflection. In particular, the elastoplastic buckling wavelength of the core members was significantly reduced and the transition from axial deformation to bending of the core member was much delayed, both of which contributing to the enhanced strength and energy adsorption capability of the foam filled panel.
A fundamental problem in control systems theory is that stability is not always guaranteed for a closed-loop system even if the plant is open-loop stable. With the only knowledge of the ...input-to-state (practical) stability (ISpS) of the plant, in this note, a bounded integral controller (BIC) is proposed which generates a bounded control output independently from the plant parameters and states and guarantees closed-loop system stability in the sense of boundedness. When a given bound is required for the control output, an analytic selection of the BIC parameters is proposed and its performance is investigated using Lyapunov methods, extending the result for locally ISpS plant systems. Additionally, it is shown that the BIC can replace the traditional integral controller (IC) and guarantee asymptotic stability of the desired equilibrium point under certain conditions, with a guaranteed bound for the solution of the closed-loop system. Simulation results of a DC/DC buck-boost power converter system are provided to compare the BIC with the IC operation.
Motivated by the recent development of phase field methods for modeling and simulating the fracture of brittle and quasi-brittle materials, a general approach is proposed to decompose the ...infinitesimal strain tensor (or Cauchy stress tensor) into a positive part and a negative part which are orthogonal in the sense of an inner product where the elastic stiffness (or compliance) tensor acts as a metric. This approach is based on a strain (or stress) transformation preserving the elastic energy, and gives rise to a generalized Pythagorean theorem. It is valid not only for the isotropic elastic case but also for all the anisotropic ones. Decompositions of the strain (or stress) tensor are given in a coordinate-free way. The main results obtained are illustrated and detailed for the elastic isotropic case in an analytical explicit manner.
•Coordinate-free decomposition of the strain tensor into positive and negative parts.•The elastic tensor acting as a metric for defining the orthogonality.•The strain orthogonal decomposition valid for all elastic symmetry classes.
This study focuses on the chemical and Sr isotopic compositions of the dissolved load of the rivers of the Changjiang Basin, one of the largest riverine systems in the world. Water samples were ...collected in August 2006 from the main tributaries and the main Changjiang channel. The chemical and isotopic analyses indicated that four major reservoirs (carbonates, silicates, evaporites and agriculture/urban effluents) contribute to the total dissolved solutes. The overall chemical weathering (carbonate and silicate) rate for the Changjiang is approximately 40
ton/km
2/year or 19
mm/kyr, similar to that of the Ganges–Brahmaputra system, and the basin is characterized by carbonate and silicate weathering rates ranging from 17 to 56
ton/km
2/year and from 0.7 to 7.1
ton/km
2/year, respectively. In the lower reach of the Changjiang main channel, the weathering rates are estimated to be 36 and 2.2
ton/km
2/year for carbonates and silicates, respectively. It appears that sulphuric acid may dominate chemical weathering reactions for some sub-basins. The budgets of CO
2 consumption are estimated to be 646
×
10
9 and 191
×
10
9
mol/year by carbonate and silicate weathering, respectively. The contribution of the anthropogenic inputs to the cationic TDS of the Changjiang is estimated to be 15–20% for the most downstream stations. Our study suggested that the Changjiang is strongly impacted by human activities and is very sensitive to the change of land use.
Solitary, persistent wave packets called solitons hold potential to transfer information and energy across a wide range of spatial and temporal scales in physical, chemical, and biological systems. ...Mechanical solitons characteristically emerge either as a single wave packet or uncorrelated propagating topological entities through space and/or time, but these are notoriously difficult to control. Here, we report a theoretical framework for programming static periodic topological solitons into a metamaterial, and demonstrate its implementation in real metamaterials computationally and experimentally. The solitons are excited by deformation localizations under quasi-static compression, and arise from buckling-induced kink-antikink bands that provide domain separation barriers. The soliton number and wavelength demonstrate a previously unreported size-dependence, due to intrinsic length scales. We identify that these unanticipated solitons stem from displacive phase transitions with periodic topological excitations captured by the well-known Formula: see text theory. Results reveal pathways for robust regularizations of stochastic responses of metamaterials.
Aim
Nod‐like receptor protein 3 (NLRP3) inflammasome‐mediated inflammation has emerged as a contributor to epileptogenesis. Endoplasmic reticulum stress (ERS) plays an important role in ...epilepsy‐induced neurodegeneration. NLRP3 activation and ERS reactions share the same induction factors, suggesting that these processes may be interdependent. However, the correlation between NLRP3 and ERS in TLE has not been confirmed.
Methods
The expression patterns of NLRP3 inflammasome and ERS‐related markers in the temporal neocortices of TLE patients were investigated by western blotting, immunohistochemistry and immunofluorescent labelling. Correlations between the protein levels of NLRP3 and the expression of ERS‐related markers were assessed using Spearman’s rank correlation test. To observe the relationship between the NLRP3 inflammasome and ERS, inhibitors were used in a status epilepticus (SE) model.
Results
Our results show that NLRP3 inflammasome components and ERS‐related markers were upregulated in the temporal neocortices of TLE patients, and were mainly localized to neurons, astrocytes and microglia. We found a positive correlation between the protein levels of NLRP3 and the expression of ERS‐related markers in the temporal neocortices of 20 TLE patients. Furthermore, after blocking the NLRP3 inflammasome with MCC950, the expression of ERS‐related markers was markedly decreased in the hippocampi of SE mice. Moreover, TUDCA, a specific ERS inhibitor, also reduced the expression of NLRP3 components in the hippocampus under SE conditions.
Conclusion
Taken together, our data reveal the interdependence of the NLRP3 inflammasome and ERS in the epileptogenic zone of TLE patients and in the hippocampi of mice in the early post‐SE phase.
Zika virus, an arbovirus transmitted by mosquitoes of the Aedes species, is now rapidly disseminating throughout the Americas and the ongoing Brazilian outbreak is the largest Zika virus epidemic so ...far described. In addition to being associated with a non-specific acute febrile illness, a number of neurological manifestations, mainly microcephaly and Guillain-Barré syndrome, have been associated with infection. These with other rarer neurological conditions suggest that Zika virus, similar to other flaviviruses, is neuropathogenic. The surge of Zika virus-related microcephaly cases in Brazil has received much attention and the role of the virus in this and in other neurological manifestations is growing. Zika virus has been shown to be transmitted perinatally and the virus can be detected in amniotic fluid, placenta and foetus brain tissue. A significant increase in Guillain-Barré syndrome incidence has also been reported during this, as well as in previous outbreaks. More recently, meningoencephalitis and myelitis have also been reported following Zika virus infection. In summary, while preliminary studies have suggested a clear relationship between Zika virus infection and certain neurological conditions, only longitudinal studies in this epidemic, as well as experimental studies either in animal models or in vitro, will help to better understand the role of the virus and the pathogenesis of these disorders.
PDF
