[en] Highlights: • The friction force pattern is revealed. • The dimensionality reduction effect is studied. • The condition of atomic appearance is determined. - Abstract: In this paper, the experimental and theoretical studies on the atomic-scale two-dimensional friction force pattern are presented. Atomic-scale friction experiments were conducted on graphite surfaces with the atomic force microscopy (AFM) under ambient conditions. Owing to the dimensionality reduction effect of optical method detecting the probe cantilever deflection, the friction force patterns were revealed in these experiments. The friction phenomenon was analyzed theoretically in the framework of Prandtl–Tomlinson model in two dimensions. The dimensionality reduction effect was formulated and involved in the model. The comparison shows the good quantitative agreement between experimental and simulation results, suggesting that the friction force pattern can be interpreted reliably using the model. Meanwhile atomic arrangement was obtained in friction force pattern, the origin and variation of which were also analyzed. The condition for appearance of atomic arrangement was determined qualitatively. By means of band-pass filtering, hexagonal rings or crystal lattices images of graphite were obtained

[en] We consider a harmonic oscillator with delays. Linear stability is investigated by analyzing the associated characteristic transcendental equation. The bifurcation analysis of the equation shows that Hopf bifurcation can occur as the delay τ (taken as a parameter) crosses some critical values. The direction and stability of the Hopf bifurcation are considered by using the normal form theory due to Faria and Magalhaes. An example is given to explain the results. Numerical simulations support our results

[en] Objective: To study changes and interrelations of TNF - α, NOS activity and NO in the plasma of patients with chronic congestive heart failure (CHF). Methods: The blood samples were taken from eighty patients and twenty healthy subjects. Plasma TNF - α was measured by RIA. Plasma NOS activity and NO were assessed with colorimetric analysis. Results: The level of plasma TNF - α, NOS activity and NO were significantly higher in CHF patients than that in healthy subjects and were increased with the severity of heart failure. The levels of TNF - α, NOS activity and NO showed significant relation with each other and all of them were closely related to the ejection fraction. Conclusion: TNF - α, NOS activity and NO increase greatly in patients of CHF and they maybe play an important roles in the progress of CHF. They can be used as markers for the severity and prognosis of heart failure

[en] In this paper, by incorporating the gene expression time delay into a diffusive Brusselator model, a diffusive Brusselator model with gene expression time delay is proposed, and the Turing-Hopf bifurcation of the proposed model subject to homogeneous Neumann boundary condition is investigated. Firstly, the condition for the occurrence of Turing instability is deduced, and the existence of Turing bifurcation, Hopf bifurcation and Turing-Hopf bifurcation for the proposed model is also established. Then by a slight modification, the normal form on the center manifold near the Turing-Hopf singularity for the proposed model is derived by using the algorithm of calculating the normal form of Turing-Hopf bifurcation for the general reaction diffusion system with delay. With the aid of the obtained third-order truncated normal form of the proposed model, the spatiotemporal dynamics corresponding to six different regions in the parameter plane are analyzed. Moreover, by the corresponding relationships between the equilibrium points of the normal form and the solutions of original system, the dynamics of the original system can also be obtained. Finally, some numerical simulations are carried out to support the theoretical findings.

[en] Hydrophobic ZnO self-cleaning thin films with the nanobundles and nanocarpets structures fabricated on indium tin oxides (ITO) glass substrate are reported. The water contact angle of ZnO nanobundles and nanocarpets structures (79° and 67° respectively) is higher than that of unmodified ZnO nanorods. A subsequent chemical treatment with stearic acid (SA) contributed to a superhydrophobic surface with a water contact angle of 159°. Its superhydrophobic property is originated from the nanobundles or nanocarpets structures and surface energy of SA/ZnO nanobundles and SA/ZnO nanocarpets composite nanostructures. Moreover, this promising ZnO nanostructured materials show an important application in self-cleaning smart coatings. - Highlights: • PEG and CTAB are firstly introduced to modify the morphology of ZnO seed layers. • ZnO nanobundles and nanocarpets obtained from different seed layers. • Superhydrophobic surfaces obtained by chemcial treatment using SA.

[en] An experiment on vacuum electron beam welding procedure for typical aluminum alloy work-piece with flange circumferential weld was introduced in detail. The reason of porosity produced when welding aluminum alloy is analyzed and some corresponding processing are taken to achieve welding with good quality

[en] Highlights: • The free-standing rGO hydrogel film is conveniently prepared by hydrothermal method. • The rGO hydrogel film is used as working electrode for PANI electropolymerization. • The rGO/PANI composite film exhibits high specific capacitance and rate capability. • The composite films are assembled into high-performance symmetric supercapacitor. -- Abstract: The combination of graphene and polyaniline (PANI) as electrodes for supercapacitors has attracted dramatic interests due to their synergistic effects. However, the preparation of the electrode materials usually involves complicated process and other additives. In this work, we report the facile fabrication of the graphene/PANI composite hydrogel film as the symmetric all-solid-state supercapacitor electrode. The free-standing reduced graphene oxide (rGO) hydrogel film is hydrothermally synthesized from a GO solution layer, which is used for subsequent electropolymerization of PANI. The electrochemical measurements of the resulting rGO/PANI hydrogel film present the capacitance of 853.7 F g⁻¹ at 1 Ag⁻¹ with good rate capability and cycling stability. In addition, the hydrogel composite film is assembled into the symmetric all-solid-state capacitor without any additives and attains the capacitance of 741.8 F g⁻¹ with a high capacitance retention of 92.6% after 8000 cycles. These excellent electrochemical properties of the composite film are ascribed to the joint effort of superior conductivity and porous structure of rGO matrix with the outstanding pseudocapacitive property of PANI. The convenient method could be considered for the preparation of graphene-based functional composite materials.

[en] Rest thallium-201 (²⁰¹Tl) myocardial perfusion imaging has been widely used for evaluation of myocardial ischemia/viability after myocardial infarction, but the ideal timing for imaging after injection to maximally estimate viability is not well established. Thirty-six patients with myocardial infarction underwent the initial, 3 h, and 24 h redistribution imaging after intravenous injection of 148-185 MBq ²⁰¹Tl. The initial and 3 h images, the initial and 24 h images, and the 3 and 24 h images were compared double-blinded. Out of the 184 abnormal segments based on the initial imaging, 56 (30%) segments improved by at least 1 grade on the 3 h imaging while 78 (42%) segments improved by at least 1 grade on the 24 h imaging. The 24 h late imaging detected more viable myocardium than the 3 h imaging did, with a significant difference (χ²=5.680, p=0.017). There were 158 abnormal segments on the 3 h imaging, with average 28% (44) segments improved by at least 1 grade on the 24 h imaging. There were 128 initial abnormal segments with no improvement on the 3 h imaging. Out of these segments, the 24 h late redistribution imaging detected additional redistribution in 26 segments, taking up 20%. Twenty-four hour late ²⁰¹Tl imaging will demonstrated additional redistribution in patients who have incompletely reversible defects on early redistribution imaging at 3 h. (author)

[en] Objective: To evaluate the biodistribution and imaging of technetium -99m labeled Nateglinide: ⁹⁹Tc^m-DTPA-Nateglinide (⁹⁹Tc^m-DTPA-NGN2) in mice. Methods: Forty-two healthy Kunming mice were divided into 7 groups. Five minutes,15 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, and 6 hours after the injection of 3.7 MBq ⁹⁹Tc^m-DTPA-NGN2, these mice were sacrificed by cutting the carotid. Selected tissues (heart, liver, spleen, lung, brain, kidney, muscle, bone, intestine, stomach, pancreas and blood) were excised and weighed, and the radioactivity was measured. The biodistribution of radiotracer in each tissue sample was calculated as a percentage of the injected dose per gram of wet tissue weight (%ID/g). Another 5 mice were imaged after the injection of 18.5 MBq ⁹⁹Tc^m-DTPA-NGN2 at the same time. Result: ⁹⁹Tc^m-DTPA-NGN2 is metabolized mainly from kidney,brain doesn't uptake ⁹⁹Tc^m-DTPA-NGN2, the %ID/g of the selected tissues were decreased rapidly in 1 hour, and the radioactivity in pancreas kept stable from 1 hour to 2 hours after injection. The pancreas visualized clearly 1 hour after injection. Conclusion: ⁹⁹Tc^m-DTPA-NGN2 can be clearly visualized in pancreas in mice,and maybe it's promising in imaging pancreatic tumor and in evaluating the function of pancreatic B cell. (authors)

[en] Highlights: • We study a predator-prey model with predator-age structure. • Research methods involve integrated semigroup theory and Hopf bifurcation theory. • The existence of Hopf bifurcation is established. • Simulations and sensitivity analysis are performed to illustrate the conclusions. -- Abstract: A novel Michaelis–Menten type ratio-dependent predator–prey model with predator-age structure is investigated. The predator fertility function is considered to be the piecewise function related to predator maturation period $\tau$. Our methods rely upon integrated semigroup theory and Hopf bifurcation theory for semilinear equations with non-dense domain. By local analysis and bifurcation analysis of the model, a non-trivial periodic oscillation phenomenon through Hopf bifurcation appears when parameter $\tau$ passes through some critical values. Numerical simulations and sensitivity analysis on several important parameters are also performed to illustrate the conclusions.