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Purpose. Gastric cancer (GC) is one of the most common malignant tumors and also one of the most deadly tumors. In recent years, studies have shown that propofol can inhibit the proliferation and metastasis of many tumor cells. In the present study, we aimed to investigate the underlying mechanism of propofol inhibition of the growth and invasion of GC cells. Methods. Human gastric cancer cell line SGC-7901 and human normal gastric epithelial cell GES-1 were cultured in high-glucose Dulbecco’s Modified Eagle’s Medium (DMEM) supplemented with 10% fetal bovine serum at 37°C with 5% CO2. Propofol of different concentrations (0, 2, 5, and 10 μg/mL) was used to treat SGC-7901, and miR-493-3p inhibitor was transfected into SGC-7901. The cell proliferation of SGC-7901 was analyzed by MTT as well as colony formation assay. The qRT-PCR was used to assess the expression of mRNA for key genes. We examined the protein expression of DKK1 and relative markers with western blot. Putative binding places of miR-493-3p on the 3 ′ -untranslated area of DKK1 were predicted using bioinformatics and dual-luciferase method. Results. Propofol prohibited phenotypic features of GC, according to our findings. Furthermore, research into the underlying mechanisms of propofol’s suppressive effects in GC cell proved that propofol therapy improved the degrees of expression of the potential tumor suppressor miR-493-3p. The inhibiting properties of propofol on GC cell development, migration, and invasion were abolished when propofol-induced miR493-3p was silenced with anti-miR-493-3p. We also found that this drug reversed epithelial-mesenchymal transformation in SGC-7901 cells via inducing miR-493-3p. Propofol-induced miR-493-3p decreases GC cell development via targeting DKK1 and hence inhibits Wnt/β-catenin signaling, according to these findings. Conclusion. Propofol-induced miR-493-3p decreased GC cell development via targeting DKK1 and hence inhibited Wnt/β-catenin signaling, according to these findings.

Quantum dots are often called artificial atoms because, like real atoms, they confine electrons to quantized states with discrete energies. However, although real atoms are identical, most quantum dots comprise hundreds or thousands of atoms, with inevitable variations in size and shape and, consequently, unavoidable variability in their wavefunctions and energies. Electrostatic gates can be used to mitigate these variations by adjusting the electron energy levels, but the more ambitious goal of creating quantum dots with intrinsically digital fidelity by eliminating statistical variations in their size, shape and arrangement remains elusive. We used a scanning tunnelling microscope to create quantum dots with identical, deterministic sizes. By using the lattice of a reconstructed semiconductor surface to fix the position of each atom, we controlled the shape and location of the dots with effectively zero error. This allowed us to construct quantum dot molecules whose coupling has no intrinsic variation but could nonetheless be tuned with arbitrary precision over a wide range. Digital fidelity opens the door to quantum dot architectures free of intrinsic broadening-an important goal for technologies from nanophotonics to quantum information processing as well as for fundamental studies of confined electrons.

International audience; Thermally activated rotation of single molecules adsorbed on a silicon-based surface between 77 and 150 K has been successfully achieved. This remarkable phenomenon relies on a nanoporous supramolecular network, which acts as a template to seed periodic molecule rotors on the surface. Thermal activation of rotation has been demonstrated by STM experiments and confirmed by theoretical calculations.

Scanning tunneling microscopy (STM) at 5 K reveals that native atoms in the surface layer of a semiconductor crystal become bistable in vertical height when a nanostructure is assembled nearby. The binary switching of surface atoms, driven by the STM tip, changes their charge state. Coupling is facilitated by assembling adatom chains, allowing us to explore the emergence of complex multiple switching. Density-functional theory calculations rationalize the observations and a lattice-gas model predicts the cooperative behavior from first principles.

The effect of thermal treatments up to 1300 K on the surface structure of MoS 2 was studied using scanning tunneling microscopy. The surface of MoS 2 remained atomically perfect up to 1200 K. Above 1300 K, a reconstruction of the top layers of MoS 2 to Mo 2 S 3 was observed, leading to one-dimensional atomic double rows on the reconstructed surface. First principles based thermodynamic calculations indicate that the thermodynamically preferred surface is the sulfur rich (0 0 1) termination. Low voltage STM simulations using the ESQC method show good agreement with experimental images.

Quantum-dot molecules were constructed on a semiconductor surface using atom manipulation by scanning tunneling microscopy (STM) at 5 K. The molecules consist of several coupled quantum dots, each of which comprises a chain of charged adatoms that electrostatically confines intrinsic surface-state electrons. The coupling takes place across tunnel barriers created reversibly using the STM tip. These barriers have an invariant, reproducible atomic structure and can be positioned---and repeatedly repositioned---to create a series of reconfigurable quantum-dot molecules with atomic precision.

On a native graphite surface, 15 nm-thick solid-state nanogears are nanofabricated with a 30 nm outer diameter and six teeth. The nanogears are manipulated one at a time by the tip of an atomic force microscope using the sample stage displacements for the manipulation and recording of the corresponding manipulation signals. For step heights below 3.0 nm, nanogears are manipulated up and down native graphite surface step edges. In the absence of a central shaft per nanogear, gearing between nanogears is limited to a few 1/12 turns for six teeth. When the graphite step is higher than 3 nm, a rack-and-pinion mechanism was constructed along the edge with a 90 nm nanogear pinion.

P21-activated kinases (PAKs) are small guanosine triphosphate effectors that play critical roles in many fundamental cellular functions, including cytoskeletal reorganization and cell motility. PAKs are widely expressed in a variety of tissues and are often overexpressed in multiple cancer types. The aim of this study was to investigate the relationship between PAK1 and PAK4 and clinicopathologic features of colorectal cancer.PAK1 and PAK4 expression in colorectal cancer patients were investigated via TaqMan real-time polymerase chain reaction and immunohistochemistry and clinical analysis.The relative expression levels of PAK1 and PAK4 gene in colorectal carcinoma tissues were significantly higher than those in normal tissues (P0.01). PAK4 expression was higher than PAK1 in the same cancer tissue. The expression of PAK1 and PAK4 increased gradually with the clinical stages in carcinoma tissues (P0.01). PAK1 expression was higher in lymph node positive patients, and PAK4 expression was higher in infiltration into serous layer patients (P0.05). PAK1 overexpression group has a higher recurrence/metastasis rate compared with that of the PAK1 low expression group. Follow-up analysis showed that the median progression-free survival time of the PAK1 high expression group was significantly shorter than that of the PAK1 low expression group.PAK1 and PAK4 expression were associated with colorectal cancer metastasis and infiltration, PAK1 high expression may indicate poor prognosis of colorectal cancer.

The morphological evolution of ErSi 2 nanowires on Si(001) with Er coverage was investigated by scanning tunnelling microscopy, low-energy electron diffraction and x-ray diffraction. At low Er coverages, elongated ErSi 2 nanowires in a hexagonal crystal structure are formed. The nanowires are exclusively oriented perpendicular to the dimer rows of the Si(001) substrate, thus suggesting a method to control the nanowire arrangement via the substrate configuration. At 3 ML of Er rectangular islands with flat tops are observed, which crystallize in the tetragonal lattice of ErSi 2 . Our experiments suggest that the structural transformation from hexagonal to tetragonal takes place when the nanostructures reach the height of the c-axis of the tetragonal unit cell.

The initial stages of ErSi2 formation on Si(0 0 1) are investigated by scanning tunneling microscopy and low energy electron diffraction. At sub-monolayer coverages two Er-induced superstructures are observed, where Er dimers are replacing the Si dimers. In the c(4×2) phase Er dimers alternate with Si dimers both along and perpendicular to the Si dimer row direction. The (2×3) phase, which evolves naturally from the c(4×2) phase with increasing coverage, consists of two adjacent chains of Er dimers and can be regarded as a precursor of the strain-field-controlled ErSi2 nanowire growth.

The surface structures of thin erbium silicide layers formed on Si(1 0 0) substrate by solid phase epitaxy are studied by using the in situ high energy electron diffraction, low energy electron diffraction, Auger electron spectroscopy, scanning tunneling microscopy, and ex situ grazing X-ray diffraction. Nanowires and nanoislands of Er silicide coexist on the Si substrate surface and a c(2×2) reconstruction is observed on the top of these nanostructures. The crystalline structure of the Er silicide nanostructure is found to be tetragonal ErSi2. A Si-adatom model for the c(2×2) reconstruction is proposed. The total energy calculation based on the discrete-variational self-consistent multipolar cluster method identifies that the hollow site Si adatom model might be the most energetically favorable one.

In this work, erbium silicide is grown on the Si(1 0 0) surface by depositing Er onto the substrate and annealing at 600–700 °C. Many nanowires of Er silicide are formed with lengths in the range 10–100 nm. The formation and evolution of this nanostructure are investigated at atomic scale directly with scanning tunneling microscopy and low-energy electron diffraction. The direction of these nanowires is found perpendicular to that of Si dimer rows. It is shown that Er coverage and annealing temperature have an effect on the formation of nanowires. On the surface between nanowires, new (5×2) and c(5×4) reconstructions are observed, giving an implication to understand the growth behaviors of Er silicide on Si(1 0 0) surface.

The synergism of CeCl3 (Ce) with cysteine (Cys) on the corrosion of P110 carbon steel in 3% NaCl solutions was investigated by electrochemical methods and surface analysis. The results showed that CeCl3 and cysteine do little to inhibit the corrosion of carbon steel, but the combination of CeCl3 with cysteine has obvious synergistic effect on the corrosion of carbon steel and the corrosion inhibition efficiency was improved significantly. The potentiodynamic polarization curves indicated that the mixture of CeCl3 and cysteine acts as a cathodic inhibitor. Scanning electron microscope (SEM) and Infrared (IR) reflection spectra showed the synergistic inhibition effect was formed by the complexes between rare earth Ce(III) ion and amino acid.

Lung cancer is a common malignant neoplasm that is prone to distant metastasis. However, the incidence of multiple cutaneous and intestinal metastases is rare. The present study describes the case of a 62-year-old female who was admitted to The Affiliated Hospital of Shandong Academy of Medical Sciences in August 2013 with multiple cutaneous lumps. Contrast-enhanced computed tomography showed nodules and masses in the right lung, and multiple enlarged lymph nodes in the mediastinum and right hilum. Biopsies of the lumps in the right lung and skin revealed moderately-differentiated adenocarcinoma, which were considered to be cutaneous metastases of lung cancer. The patient subsequently experienced symptoms of rectal irritation. A digital rectal examination and colonoscopy were performed, and the consequent pathological biopsy identified moderately-differentiated adenocarcinoma. After analyzing the results of previous pathological examinations and immunohistochemistry, it may be suggested that intestinal metastasis had developed. This case highlights the fact that a comprehensive analysis and examination should be performed for suspected cutaneous and intestinal lesions, during which, a pathological biopsy is of great importance in order to form the correct diagnosis for timely treatment.

The surface of Si(1 1 1) exposed to NH3 or NO is analyzed with scanning tunneling microscopy, low-energy electron diffraction (LEED), Auger electron spectroscopy, and transmission electron microscopy. Crystalline silicon nitride thin films are formed on Si(1 1 1) after nitridation at T>1075 K. Corresponding to the 8×8 LEED pattern, a 30.7-A periodic superstructure is observed. The film thickness is saturated at 20 A. Among all known Si3N4 phases, the nitride film on Si(1 1 1) probably is β-Si3N4, then the 30.7-A superstructure is the 4×4 reconstruction on Si3N4(0 0 0 1). The possibility that the film is a new silicon nitride phase also exists. An 8/3×8/3 quasi-periodic structure is formed at T⩽1075 K or when the gas purity is degraded. The “quadruplet” LEED spots are related to carbon contamination. Etching happens during nitridation, which limits the nitride film thickness. Impurities in the nitridant enhance etching. The effectiveness of different nitridants is discussed.

Silicon carbide(SiC) nano-crystallites are formed by the thermal reaction of C60 molecules with silicon atoms on Si(0 0 1) and Si(1 1 1) surfaces at 900–11508C. The surface morphologies and structures of the cubic b-SiC islands on Si(0 0 1) and Si(1 1 1) are investigated in situ using scanning tunneling microscopy. Comparing to bulk SiC crystals, distinctive atomic structures are formed on the surfaces of the SiC crystallites: a (2 � 3) on SiC(0 0 1) and a ð2 ffiffiffi 3 p �

The surface structures of 3C–SiC(1 1 1) crystallized islands formed by thermal chemical reaction between silicon substrate and adsorbed C 60 molecules at high temperatures are studied using ultrahigh vacuum scanning tunneling microscopy (UHV-STM). The STM images show a strong bias voltage dependence, transforming between (2×2), (2 3 ×2 3 ) - R 30° and Y-type patterns under different bias voltages. A surface atomic structural model containing quarter coverage of vacancies and three different sites of surface silicon atoms is proposed to interpret the experimental observations. The dangling bond electronic states contributed by these different site Si atoms on the outermost surface layer and by the carbon atoms surrounding the vacancies are suggested to be responsible for the different tunneling conditions under different bias voltages in STM images.

After exposing Si(111) to NH 3 at about 1075 K, a 10.2-A surface periodic structure (the ‘8/3×8/3’ reconstruction) is observed in scanning tunneling microscopy images. When the nitridation temperature is above 1125 K, a silicon nitride film with a surface superstructure with a period of 30.7 A and a minimum step height of 2.9 A is obtained. Our systematic analyses suggest that the 30.7-A superstructure is the 4×4 reconstruction on the Si 3 N 4 (0001) surface of the crystalline silicon nitride ( β -Si 3 N 4 ) thin film formed on Si(111), while the 10.2-A periodic structure is an incomplete nitridation phase on Si(111) surface. The surface structure has been found to be sensitive to the impurities in NH 3 .

The structure and morphology of amorphous Ni 88 P 12 alloy films prepared by chemical deposition on p-Si(100) substrates at 363 K are studied by scanning tunneling microscopy, atomic force microscopy and X-ray diffraction before and after treatments of oxidation–reduction and crystallization. The results show that amorphous Ni 88 P 12 alloy films are an assembly of micrometer-scale grains, each of which consists of nanoparticles. The surface crystallites form when the films are treated by an oxidation–reduction cycle at temperatures below the normal crystallization temperature. Two kinds of grains with different shapes have been detected. The morphological features of the crystallites developed from the nanoparticles of the amorphous film after crystallization is described.

The thin film of Ni P amorphous alloy deposited on the p-type silicon slice was prepared by electroless plating, which was then crystallized by heating it at high temperature from 550 K to 610 K in nitrogen flow for 2 h. Its crystallization process was investigated by using ICP, XRD, XPS, TEM, SEM and STM. No significant changes in the composition and the electronic structure on the surface have been observed during the crystallization process. However the changes in the amorphous structure and the surface area as well as the surface morphology are observed, which are attributed to the deactivation of the amorphous alloy after annealing during the hydrogenation reactions. Experimental results also reveal that the diffusion of the component elements in the Ni P alloy is essential during the crystallization because various crystalline diffraction peaks corresponding to Ni and Ni 3 P are observed simultaneously on XRD patterns. Based on those results, some modifications have been described to improve the thermal stability of the amorphous alloy.

Scanning tunneling microscopy of longitudinally polarized surface acoustic waves (SAWs) yields amplitude and phase images with nanometer resolution. The eccentricity of the surface oscillation calculated from the experimental data by the model of Chilla et al. is 88°±5° in good agreement with the macroscopic value for high velocity pseudo SAWs. Our study reveals that reliable amplitude and phase information can be deduced even from atomic scale features; however, the local surface geometry and tip shape need to be treated in more detail.

In consideration of personal wealth and public security, time is one of the most significant factors influencing the real-time web service, such as E-Commerce, aviation, military affairs, etc. However, there is no suitable timed model for OWL-S to support modeling the real-time web service in semantic web. In this paper, web service is defined in OWL-S, the standard ontology language of semantic web. Then, in order to formal analyses the time property of web services, Timed CSP which is an extension of Hoare's CSP is utilized to model OWL-S in detail. Finally, Our future working plan is also given in this paper.

The vertical manipulation of native adatoms on a III-V semiconductor surface was achieved in a scanning tunneling microscope at 5 K. Reversible repositioning of individual In atoms on InAs(111)A allows us to construct one-atom-wide In chains. Tunneling spectroscopy reveals that these chains host quantum states deriving from an adatom-induced electronic state and substantial substrate-mediated coupling. Our results show that the combined approach of atom manipulation and local spectroscopy is capable to explore atomic-scale quantum structures on semiconductor platform.

We achieved the repositioning of native In adatoms on the polar III-V semiconductor surface InAs(111)A-(2 × 2) with atomic precision in a scanning tunnelling microscope (STM) operated at 5 K. The repositioning is performed by vertical manipulation, i.e., a reversible transfer of an individual adatom between the surface and the STM tip. Surface-to-tip transfer is achieved by a stepwise vibrational excitation of the adsorbate-surface bond via inelastic electron tunnelling assisted by the tip-induced electric field. In contrast, tip-to-surface back-transfer occurs upon tip-surface point contact formation governed by short-range adhesive forces between the surface and the In atom located at the tip apex. In addition, we found that carrier transport through the point contact is not of ballistic nature but is due to electron tunnelling. The vertical manipulation scheme used here enables us to assemble nanostructures of diverse sizes and shapes with the In adatoms residing on vacancy sites of the (2 × 2)-reconstructed surface (nearest-neighbour vacancy spacing: 8.57 Å).

By means of low-temperature scanning tunneling microscopy at 5 K, the authors demonstrate the controlled and reversible vertical manipulation of native In adatoms on the InAs(111)A surface grown by molecular beam epitaxy. Monatomic In adatom chains are constructed by positioning In atoms one by one. Scanning tunneling spectroscopy and spatial mapping of the differential tunneling conductance reveal substantial along-chain electronic coupling. This coupling results in the formation of chain-localized quantum states, which can be described as the bonding ground-state orbital in an artificial linear molecule.

The manipulation of single metallic nanoislands with a precision better than 0.5nm on a MoS2 surface is demonstrated. Optimizing the metal growth conditions yields triangular-shaped nanoislands of 30nm in lateral size and 12nm in height on the MoS2 surface. The manipulation of a single nanoisland was performed using the tip apex of a scanning tunneling microscope. The feedback loop conditions to achieve this manipulation are discussed. Fully planar four-pad nanostructures were constructed, and the apex of each triangular nanoisland of the nanostructure is pointing toward a central 10×20nm2 MoS2 working area where the surface atomic cleanliness is preserved.

The scanning tunneling microscope (STM) has proven to be a powerful technique for probing surface acoustic waves (SAWs) with high spatial resolution. Here we use our ultrahigh-vacuum SAW-STM to investigate a Rayleigh wave excited in LiNbO3 with emphasis laid on the SAW-induced signals at steps that are only a few atomic layers high. Our study reveals that on the length scale of a few nanometer the description of the amplitude and phase contrast by a plain geometrical model fails and a variety of other mechanisms decisively affect the SAW-induced signal. At steps the lateral surface movement due to the SAW may play an important role. For larger step inclination angles also the shape of the STM tip as well as tip-surface interactions become relevant, which may even drive a SAW-induced movement of the tip apex.

Crystalline silicon nitride (SiN x ) thin films on Si(111) and amorphous SiN x films on Si(001) have been obtained after NH3 or NO exposure at T≈1175 K. The crystallinity of the film on Si(111) has been verified with high-resolution cross-sectional transmission electron microscopy (TEM) and scanning tunneling microscopy. The thickness of the SiN x film is 3–6 atomic layers. When compared with the known phases of Si3N4, our SiN x film is relatively close to β-Si3N4, but it could be a new phase of silicon nitride. Si or Ge forms 3D islands initially when deposited on both crystalline and amorphous SiN x films, and most of the islands are not aligned with the Si substrates. However, on SiN x /Si(111), the islands aligned with the Si substrate grow faster than other islands, so that the overlayer gradually grows into a (111)-oriented columnar film. On SiN x /Si(001), the overlayer films remain polycrystalline in later stages of growth.

We present a technique for metal-organic-metal junctions, which contain ten or fewer conjugated molecules between each of such junction, and the investigations of the I–V response of these junctions. The junctions are made by self assembling thiolated molecules onto gold coated tips for use in scanning tunneling microscopy. We show that this easy technique probes the qualitative properties of the molecules. Current-voltage characteristics of a Tour wire and a new molecular rectifier are presented.