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In this paper, decoupling of a compact isosceles triangular array is performed by a hybrid method consisting of loaded parasitic element (LPE) in combination with decoupling and matching network (DMN). By introducing a reactively loaded parasitic element at a suitable position on the axis of symmetry of the isosceles triangle, not only are the mutual couplings between the element at the vertex and the two elements on the base eliminated but also the circuit parameters of the base elements are well prepared for a DMN of a simpler form. Thus, the impedance matching of the vertex element and the decoupling and matching of the base elements can be implemented independently. The DMN of base elements comprises two impedance-transforming sections (ITS) and a $\pi $ -shaped neutralization section (NS). The ITSs inserted between the antennas and NS convert the self-conductance to the system admittance and the trans-conductance to zero. The trans-susceptance is then compensated through the main line of the NS independently, and self-susceptance is canceled out by adjusting the tapped stubs subsequently. With all the explicit formulas derived, the design is systematic and straightforward. The presented compact isosceles triangular array with element separations of $0.1\lambda $ and $0.2\lambda $ is fabricated and measured. The results show that sound isolation of 35 dB and return loss of 21 dB is obtained with ECCs less than 0.02, validating the effectiveness of the hybrid decoupling technique.

Abstract Background C-Myc is a short-lived oncoprotein that is destroyed by ubiquitin-mediated proteolysis. Dysregulated accumulation of c-Myc commonly occurs in human cancers. Some of those cases with the dysregulated c-Myc protein accumulation are attributed to gene amplification or increased mRNA expression. However, the abnormal accumulation of c-Myc protein is also a common finding in human cancers with normal copy number and transcription level of c-Myc gene. It seems that the mechanistic dysregulation in the control of c-Myc protein stabilization is another important hallmark associated with c-Myc accumulation in cancer cells. Here we report a novel mechanistic pathway through which DNA-dependent protein kinase catalytic subunit (DNA-PKcs) modulates the stability of c-Myc protein. Results Firstly, siRNA-mediated silencing of DNA-PKcs strikingly downregulated c-Myc protein levels in HeLa and HepG2 cells, and simultaneously decreased cell proliferation. The c-Myc protein level in DNA-PKcs deficient human glioma M059J cells was also found much lower than that in DNA-PKcs efficient M059K cells. ATM deficiency does not affect c-Myc expression level. Silencing of DNA-PKcs in HeLa cells resulted in a decreased stability of c-Myc protein, which was associated the increasing of c-Myc phosphorylation on Thr58/Ser62 and ubiquitination level. Phosphorylation of Akt on Ser473, a substrate of DNA-PKcs was found decreased in DNA-PKcs deficient cells. As the consequence, the phosphorylation of GSK3 β on Ser9, a negatively regulated target of Akt, was also decreased, and which led to activation of GSK 3β and in turn phosphorylation of c-Myc on Thr58. Moreover, inhibition of GSK3 activity by LiCl or specific siRNA molecules rescued the downregulation of c-Myc mediated by silencing DNA-PKcs. Consistent with this depressed DNA-PKcs cell model, overexpressing DNA-PKcs in normal human liver L02 cells, by sub-chronically exposing to very low dose of carcinogen 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), increased c-Myc protein level, the phosphorylation of Akt and GSK3 β, as well as cell proliferation. siRNA-mediated silencing of DNA-PKcs in this cell model reversed above alterations to the original levels of L02 cells. Conclusion A suitable DNA-PKcs level in cells is necessary for maintaining genomic stability, while abnormal overexpression of DNA-PKcs may contribute to cell proliferation and even oncogenic transformation by stabilizing the c-Myc oncoprotein via at least the Akt/GSK3 pathway. Our results suggest DNA-PKcs a novel biological role beyond its DNA repair function.