Growth of Large Domain Epitaxial Graphene on the C-Face of SiC

Growth of epitaxial graphene on the C-face of SiC has been investigated. Using a confinement controlled sublimation (CCS) method, we have achieved well controlled growth and been able to observe propagation of uniform monolayer graphene. Surface patterns uncover two important aspects of the growth, i.e. carbon diffusion and stoichiometric requirement. Moreover, a new "stepdown" growth mode has been discovered. Via this mode, monolayer graphene domains can have an area of hundreds of square micrometers, while, most importantly, step bunching is avoided and the initial uniformly stepped SiC surface is preserved. The stepdown growth provides a possible route towards uniform epitaxial graphene in wafer size without compromising the initial flat surface morphology of SiC.Comment: 18 pages, 8 figure

Neural differentiation of adipose-derived stem cells by indirect co-culture with Schwann cells

To investigate whether adipose-derived stem cells (ADSCs) could be subject to neural differentiation induced only by Schwann cell (SC) factors, we co-cultured ADSCs and SCs in transwell culture dishes. Immunoassaying, Western blot analysis, and RT-PCR were performed (1, 3, 7, 14 d) and the co-cultured ADSCs showed gene and protein expression of S-100, Nestin, and GFAP. Further, qRT-PCR disclosed relative quantitative differences in the above three gene expressions. We think ADSCs can undergo induced neural differentiation by being co-cultured with SCs, and such differentia­tions begin 1 day after co-culture, become apparent after 7 days, and thereafter remain stable till the 14th day

Research on Parametric Model for Surface Processing Prediction of Aero-Engine Blades

This paper presented a method for establishing a blade surface machining prediction model based on a parametric model. The abrasive grain state of the grinding tool was divided into initial wear stage, stable wear stage and sharp wear stage. Based on this, a parametric prediction model of engine blade surface material removal was established. In this paper, the simulation of blade surface machining was carried out. In this work, the blade was divided into several sections according to the direction from the blade root to the blade tip. A certain curve of the outer contour was fitted with a specific arc to reduce the calculation amount. Through a series of simulation calculations, the expressions of the above parametric prediction model were obtained, and several experiments were carried out to verify the feasibility of the prediction model, and the results were analyzed

Determination of beam incidence conditions based on the analysis of laser interference patterns

Beam incidence conditions in the formation of two-, three- and four-beam laser interference patterns are presented and studied in this paper. In a laser interference lithography (LIL) process, it is of importance to determine and control beam incidence conditions based on the analysis of laser interference patterns for system calibration as any slight change of incident angles or intensities of beams will introduce significant variations of periods and contrasts of interference patterns. In this work, interference patterns were captured by a He-Ne laser interference system under different incidence conditions, the pattern period measurement was achieved by cross-correlation with, and the pattern contrast was calculated by image processing. Subsequently, the incident angles and intensities of beams were determined based on the analysis of spatial distributions of interfering beams. As a consequence, the relationship between the beam incidence conditions and interference patterns is revealed. The proposed method is useful for the calibration of LIL processes and for reverse engineering applications

Research on Abrasive Belt Based Machining Technology for Milling Shaped Aero-Engine Blades

This paper proposes an automatic surface treatment method for CNC milled blades. The surface texture characteristics of the blade after milling were analyzed. The contact area between the contact wheel and the blade surface was analyzed theoretically, and then the contact wheel and the blade edge were analyzed. The contact area between the intake side and the exhaust side was theoretically analyzed, and one micro-element in the contact area was selected, and the simulation analysis under multiple sets of parameters was carried out. In the experimental aspect, this paper has assembled a set of relatively reliable experimental systems, and carried out an in-depth analysis of a certain area of the engine blade obtained from the experiment to verify the feasibility and reliability of the proposed method