Importance of surface morphology on secondary electron emission: a case study of Cu covered with carbon, carbon pairs, or graphitic-like layers

Understanding the relationship between surface adsorbates and secondary electronic emission is critical for a variety of technologies, since the secondary electrons can have deleterious effects on the operation of devices. The mitigation of such phenomena is desirable. Here, using the collective efforts of first-principles, molecular dynamics, and Monte Carlo simulations, we studied the effects of a variety of carbon adsorbates on the secondary electron emission of Cu (110). It was demonstrated that the adsorption of atomic C and C[Formula: see text] pair layers can both reduce and increase the number of secondary electrons depending on the adsorbate coverage. It was shown that under electron irradiation, the C-Cu bonds can be dissociated and reformed into C[Formula: see text] pairs and graphitic-like layers, in agreement with experimental observation. It was verified that the lowest secondary electron emission was due to the formation of the graphitic-like layer. To understand the physical reason for changes in number of secondary electrons for different systems from an electronic structure perspective, two-dimensional potential energy surfaces and charge density contour plots were calculated and analyzed. It was shown that the changes are strongly influenced by the Cu surface morphology and depends highly on the nature of the interactions between the surface Cu and C atoms.

Changes in the expression of smooth muscle contractile proteins in TNBS- and DSS-induced colitis in mice

Thin filament-associated proteins such as calponin, caldesmon, tropomyosin, and smoothelin are thought to regulate acto-myosin interaction and thus, muscle contraction. However, the effect of inflammation on the expression of thin filament-associated proteins is not known. The aim of the present study is to determine the changes in the expression of calponin, caldesmon, tropomyosin, and smoothelin in colonic smooth muscle from trinitrobenzene sulphonic acid (TNBS)- and dextran sodium sulphate (DSS)-induced colitis in mice. Expression of h-caldesmon, h2-calponin, α-tropomyosin, and smoothelin-A was measured by qRT-PCR and Western blot. Contraction in response to acetylcholine in dispersed muscle cells was measured by scanning micrometry. mRNA and protein expression of α-actin, h2-calponin, h-caldesmon, smoothelin, and α-tropomyosin in colonic muscle strips from mice with TNBS- or DSS-induced colitis was significantly increased compared to control animals. Contraction in response to acetylcholine was significantly decreased in muscle cells isolated from inflamed regions of TNBS- or DSS-treated mice compared to control mice. Our results show that increase in the expression of thin filament-associated contractile proteins, which inhibit acto-myosin interaction, could contribute to decrease in smooth muscle contraction in inflammation.