ABSTRACT
Purpose: The aim of this study was to investigate the protective effect of long non-coding lnc-PXMP4-2-4 on myocardial cell damage caused by acute myocardial infarction (AMI). Methods: Peripheral blood mononuclear cells (PBMC) were collected from 24 patients with AMI on the day of admission, the first day after percutaneous coronary intervention (PCI) and the third day after surgery, and 24 patients with clinical control group. Real-time quantitative PCR(QRT-PCR) was used to detect the expression of related genes. Then in human cardiomyocytes (AC16), Cell Counting Kit-8 (CCK-8) was used to determine cell viability, lactate dehydrogenase release assay (LDH) was used to determine the release of lactate dehydrogenase, PCR was used to detect the expression of genes, cell death was detected by flow cytometry, and the expression of related proteins was measured by Western blot. The effect of lnc-PXMP4-2-4 was further studied by silencing and overexpressing lnc-PXMP4-2-4. Results: Compared with clinical control group, the expression of lnc-PXMP4-2-4 in PBMC of AMI patients was significantly higher than it. Compared with pre-operation, the expression of lnc-PXMP4-2-4 was significantly up-regulated on day 1 after PCI, and recovered to pre-operation level on day 3 after surgery. In AC16 cells, lnc-PXMP4-2-4 inhibited the proliferation of AC16, promoted the release of LDH and increased cell death, aggravated the cardiomyocyte injury caused by H2O2, and inhibited the expression of JAK2 and STAT3 mRNA and protein. The up-regulation of lnc-PXMP-4-2-4 had the opposite effect. In addition, the inhibition of the signal pathway by JAK2/STAT3 pathway inhibitor AG490 partially weakened the enhanced viability of AC16 cells, decreased LDH release and apoptosis induced by lnc-PXMP4-2-4 overexpression, increased Bcl-2 expression and down-regulated Bax expression. Conclusion: Therefore, we conclude that lnc-PXMP4-2-4 protects cardiomyocytes from injury by activating the JAK2/STAT3 signaling pathway.
ABSTRACT
Metal-insulator transition is observed in the La0.8Sr0.2MnO3 thin films with thickness larger than 5 unit cells. Insulating phase at lower temperature appeared in the ultrathin films with thickness ranging from 6 unit cells to 10 unit cells and it is found that the Mott variable range hopping conduction dominates in this insulating phase at low temperature with a decrease of localization length in thinner films. A deficiency of oxygen content and a resulting decrease of the Mn valence have been observed in the ultrathin films with thickness smaller than or equal to 10 unit cells by studying the aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy of the films. These results suggest that the existence of the oxygen vacancies in thinner films suppresses the double-exchange mechanism and contributes to the enhancement of disorder, leading to a decrease of the Curie temperature and the low temperature insulating phase in the ultrathin films. In addition, the suppression of the magnetic properties in thinner films indicates stronger disorder of magnetic moments, which is considered to be the reason for this decrease of the localization length.
ABSTRACT
High resolution electron energy loss spectroscopy (HREELS) is a powerful technique to probe vibrational and electronic excitations at surfaces. The dispersion relation of surface excitations, i.e., energy as a function of momentum, has in the past, been obtained by measuring the energy loss at a fixed angle (momentum) and then rotating sample, monochromator, or analyzer. Here, we introduce a new strategy for HREELS, utilizing a specially designed lens system with a double-cylindrical Ibach-type monochromator combined with a commercial VG Scienta hemispherical electron energy analyzer, which can simultaneously measure the energy and momentum of the scattered electrons. The new system possesses high angular resolution (<0.1°), detecting efficiency and sampling density. The capabilities of this system are demonstrated using Bi2Sr2CaCu2O(8+δ). The time required to obtain a complete dispersion spectrum is at least one order of magnitude shorter than conventional spectrometers, with improved momentum resolution and no loss in energy resolution.
ABSTRACT
Highly stable water-soluble fluorescent Ag5 clusters with a quantum yield of 9.7% were synthesized using a specially designed tridentate polymer ligand by one-step reduction. The fluorescence may be associated with the dominant Ag+ species on the surface of the clusters. The resultant Ag nanoclusters were used as biomarkers to label mouse liver tissues successfully for the first time.
ABSTRACT
The surface of SrTiO(3)(110) single crystal is prepared in monophase with different reconstructions. The increase of surface Ti concentration is responsible for the evolution of the reconstruction from (4×1) to (2×8), and to a new (1×10) structure. It also induces the enhancement of the surface metallicity, characterized by the appearance of the in-gap states and the increasing Drude weight as measured by the electron and photoelectron spectroscopies. We attribute the metallicity to the reduced Ti ions, which is consistent with the observed band structures and the shift of the phonon energy. It is indicated that a heterointerface between a reduced titanate layer and SrTiO(3) crystal with unique electronic structure can be obtained by the simple treatment.
ABSTRACT
The formation process of Ag nanoparticles on SrTiO(3)(110) surface is studied by scanning tunneling microscope. The quasi-long-range ordered adsorbates pre-existing on (4×1)-reconstructed surface serve as nucleation centers and guide the growth of a uniform Ag nanoparticles array. Such a regulatory effect is further manifested by comparing the growth behavior with that on relatively flat (5 × 1)-reconstructed and rough amorphous SrTiO(3)(110) surface. It is also found that the pre-existing adsorbates on (4 × 1) remarkably enhance the thermal stability of Ag nanoparticles.
ABSTRACT
The surface reconstruction of SrTiO3(110) is studied with scanning tunneling microscopy and density functional theory (DFT) calculations. The reversible phase transition between (4×1) and (5×1) is controlled by adjusting the surface metal concentration [Sr] or [Ti]. Resolving the atomic structures of the surface, DFT calculations verify that the phase stability changes upon the chemical potential of Sr or Ti. In particular, the density of oxygen vacancies is low on the thermodynamically stabilized SrTiO3(110) surface.
ABSTRACT
Ordered iron oxide ultrathin films were fabricated on a single-crystal Mo(110) substrate under ultrahigh vacuum conditions by either depositing Fe in ambient oxygen or oxidizing preprepared Fe(110) films. The surface structure and electronic structure of the iron oxide films were investigated by various surface analytical techniques. The results indicate surface structural transformations from metastable FeO(111) and O-terminated Fe(2)O(3)(0001) to Fe(3)O(4)(111) films, respectively. The former depends strongly on the oxygen pressure and substrate temperature, and the latter relies mostly upon the annealing temperature. Our experimental observations are helpful in understanding the mechanisms of surface structural evolution in iron oxides. The model surfaces of Fe-oxide films, particularly O-terminated surfaces, can be used for further investigation in chemical reactions (e.g., in catalysis).
ABSTRACT
The formation mechanism of monolayer Al(111)1x1 film on the Si(111) radical3x radical3-Al substrate was studied by scanning tunneling microscopy and first-principles calculations. We found that the Si adatoms on the radical3x radical3-Al substrate play important roles in the growth process. The growth of Al-1x1 islands is mediated by the formation and decomposition of SiAl(2) clusters. Based on experiments and theoretical simulations we propose a model where free Si atoms exhibit a catalystlike behavior by capturing and releasing Al atoms during the Al film growth.
ABSTRACT
Mg(x)Zn(1-x)O thin films epitaxially grown on Mo(110) substrate under ultrahigh vacuum condition were studied in situ by various surface analysis techniques including x-ray photoelectron spectroscopy, Auger electron spectroscopy, low-energy electron diffraction, and high resolution electron energy loss spectroscopy. The results indicate that as-grown Mg(x)Zn(1-x)O films are soluble phase, and a phase transition from wurtzite to cubic structure occurs in the region of x = 0.55-0.67. The surface band gap can be tuned continuously with altering the content of Mg in Mg(x)Zn(1-x)O films, and its tunable window width is about 1.9 eV. Based on heterojunction and quantum well structure, this kind of materials can be applied in wide-band-gap semiconductor devices, such as short-wavelength light-emitting devices.
ABSTRACT
The interaction of zinc and faceted MgO(111) thin films prepared on a Mo(110) substrate was investigated in situ by using various surface analysis techniques, including X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, Auger electron spectroscopy, high-resolution electron energy loss spectroscopy, and low-energy electron diffraction. The results revealed that three-dimensional Zn islands exist on the faceted MgO(111) films and that no chemical interaction takes place at the interface at room temperature. Initially, deposited Zn is stable at temperatures below 400 K and diffuses into MgO at temperatures above 425 K. A portion of Zn is oxidized at approximately 10 (-6) mbar O 2 at room temperature. An interfacial phase of Zn x Mg 1- x O was formed after Zn was exposed to approximately 10 (-6) mbar O 2 at temperatures >or=500 K. The faceted structure on the MgO(111) surface is of a disadvantage for the epitaxial growth of ZnO films.
ABSTRACT
By alternate deposition of Mg and exposure of O2, layer-by-layer growth, polar MgO(111) ultrathin films with Mg-terminated or O-terminated surfaces have been successfully fabricated on Mo(110) substrate. The surface geometric structure and electronic structures of the polar MgO(111) films were investigated using surface analysis techniques including low-energy electron diffraction and photoelectron emission and electron energy loss spectroscopies. The results indicate that the O-terminated surface is of an insulating character, while for Mg-terminated surface, a prominent new surface state at 2-3 eV and appreciable density of states near Fermi level have been observed. The polar oxide films provide ideal model surfaces for further investigation of support-particle system.
ABSTRACT
A study of water on Pd/MgO(100) films prepared in situ upon Mo(100) single crystals has been performed by using low-energy electron diffraction, high-resolution electron energy-loss spectroscopy, and ultraviolet photoelectron spectroscopy in an ultrahigh vacuum system. The results show that the adsorption of water on MgO(100) film surfaces is enhanced significantly owing to the presence of Pd particles. The formation of a hydroxyl group suggests a dissociation of the water. The size and density of Pd particles on the substrate of MgO(100) films play an important part in the adsorption of water.
ABSTRACT
Ultrathin chromium oxide films were prepared on a W(100) surface under ultrahigh-vacuum conditions and investigated in situ by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and low-energy electron diffraction. The results show that, at Cr coverage of less than 1 monolayer, CrO2 is formed by oxidizing pre-deposited Cr at 300-320 K in approximately 10(-7) mbar oxygen. However, an increase of temperature causes formation of Cr2O3. At Cr coverage above 1 monolayer, only Cr2O3 is detected.
ABSTRACT
Nearly stoichiometric CeN film is synthesized on a Re(0001) substrate in an ultrahigh vacuum system involving highly active N atoms in the growth process, generated by thermal decomposition of NH3 by use of a hot tungsten filament. The electronic structure of the CeN film as prepared is equivalent to that of a single crystal observed by in situ Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). AES and XPS investigations show that CeN film is directly oxidized to CeO2 after exposure to O2 at room temperature. However, CeN changes into Ce2O3 after annealing in approximately 10(-6) mbar of O2 atmosphere at elevated temperature.
