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Ma, Feng

Publications and source records attributed to Ma, Feng.

6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

A method to identify weak points of interconnection of renewable energy resources

The increasing penetration of renewable energy resources (RERs) is challenging power grid planning and operation in maintaining grid reliability. Potential power grid reliability and stability issues may arise when large-scale RERs are connected to a weak power grid. These issues may become more significant due to the mutual interactions among RERs that are interconnected electrically close through a power network. Weakness analysis based on grid strength assessment is useful for identifying the potential weak grid issues. However, when taking into account the impact of the interactions among RERs, the weakness analysis becomes computationally challenging. Different combinations of points of interconnections (POIs) of RERs may have different impacts on grid strength at each POI. Due to the combination nature, such weakness analysis may be time-consuming when identifying the weakest combination of POIs from a large number of potential candidates in realistic power grids. To address this concern, the impact of the power network structure on grid strength is analyzed in this paper. It is found that the impact mainly depends on the impedance ratios at POIs. The findings can be summarized as two criteria to develop a recursive method for fast identification of the weakest combination in this paper. The efficacy of the proposed method is demonstrated through case studies on the IEEE 39-bus system and a realistic power grid.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2018

Inhibition of MALAT1 sensitizes liver cancer cells to 5-flurouracil by regulating apoptosis through IKKα/NF-κB pathway

Highlights: • MALAT1 knockdown inhibits liver cancer cell proliferation. • MALAT1 silence enhances apoptosis and liver cancer cells sensibility to 5-FU incubation. • MALAT1 deficiency related increase in sensitivity of liver cancer cells was associated with regulation of NF-κB. • MALAT1 knockdown reduces tumor growth in vivo. Metastasis associated lung adenocarcinoma transcript 1 (MALAT1) is involved in tumor cell growth process. However, its role and molecular mechanism in liver cancer is still not fully understood. In this study, we found that MALAT1 was significantly expressed in liver cancer cell lines. And knockdown of MALAT1 suppressed proliferation, migration and invasion of HepG2 cells, accompanied with decrease of Rho-associated coiled-coil-forming protein kinase 1 (ROCK1), α-smooth muscle actin (α-SMA), N-cadherin, Vimentin and TWIST. Significantly, MALAT1 deletion sensitized HepG2 cells to 5-FU-induced cell cycle arrest in G1 phase, as evidenced by the significant reduction in Cyclin D1 and CDK4 and increase in p53, p21 and p27 protein levels. In addition, MALAT1 knockdown triggered 5-FU induced apoptosis in HepG2 cells by inducing intrinsic apoptosis-related signals, including Cyto-c, Apaf-1, cleaved Caspase-9/-7/-3 and poly (ADP-ribose) polymerase (PARP). Furthermore, phosphorylated nuclear factor-κB (p-NF-κB) was also down-regulated by MALAT1 silence. Importantly, suppression of IKKα/NF-κB significantly elevated apoptosis and reduced liver cancer cell viability in MALAT1-knockdown cells with 5-FU incubation. The nude mice transplantation model also confirmed the promoted sensitivity of MALAT1-silenced HepG2 cells to 5-FU by blocking tumor cell proliferation and inducing apoptosis. Therefore, our data supplied a potential mechanism by which knockdown of MALAT1 might play an important role in augmenting sensitivity of HepG2 cells to 5-FU in therapeutic approaches, demonstrating suppressing of MALAT1 may serve as a combination with chemotherapeutic agents in liver cancer treatment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

A flexible multi-layer electret nanogenerator for bending deformation energy harvesting and strain sensing

Highlights: • The flexible multi-layer nanostructures PTFE device reached up to 4 times V{sub oc} and 2 times I{sub sc} than without treatment. • The multi-layer film was demonstrated as a good linearity strain sensor and showed a V{sub oc} 12.1 V at 60°. • A light-emitting diode was capable of lightened by continuous finger tapping to show the performance of device. - Abstract: We report a flexible multi-layer nanostructures polytetrafluoroethylene (PTFE) electret nanogenerator for bending deformation energy harvesting and self-powered strain sensing. The generated power was from the deformed electret PTFE film between two carbon black-silicone rubber (CBS) electrodes. We found that the nanostructures film can hold more charges resulting in more output voltage than the pure PTFE. And the charged nanostructures PTFE can reach up to 4 times voltage and 2 time current than without corona charge. To analyze the mechanical-electrical energy conversion performance with the bending deformation, it was found that the stronger accelerations on the prototype can result in a bigger open-circuit voltage (V{sub oc}) and short-circuit current (I{sub sc}) out. The multi-layer film was demonstrated a good linearity strain sensor and was showed a V{sub oc} 12.1 V at 60° bending angle. Moreover, a light-emitting diode (LED) was lightened by random continuous finger tapping to show the application of the reported device.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

A class of customized proximal point algorithms for linearly constrained convex optimization

In this paper, we propose a class of customized proximal point algorithms for linearly constrained convex optimization problems. The algorithms are implementable, provided that the proximal operator of the objective function is easy to evaluate. We show that, with special setting of the algorithmic scalar, our algorithms contain the customized proximal point algorithm (He et al., Optim Appl 56:559–572, 2013), the linearized augmented Lagrangian method (Yang and Yuan, Math Comput 82:301–329, 2013), the Bregman Operator Splitting algorithm (Zhang et al., SIAM J Imaging Sci 3:253–276, 2010) as special cases. The global convergence and worst-case convergence rate measured by the iteration complexity are established for the proposed algorithms. Numerical results demonstrate that the algorithms work well for a wide range of the scalar.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Hypoxia-induced activation of Twist/miR-214/E-cadherin axis promotes renal tubular epithelial cell mesenchymal transition and renal fibrosis

Highlights: • miR-214-3p mediated EMT in human tubular epithelial cells under hypoxic conditions. • Twist was activated by hypoxia and positively correlated with miR-214-3p expression. • miR-214-3p mediated EMT through downregulation of E-cadherin expression. • miR-214-3p sponge AAV attenuated the hypoxia-mediated EMT and renal fibrogenic effect. The epithelial-to-mesenchymal transition (EMT) induced by chronic hypoxia is one of the critical causes of renal fibrosis. Previous work reported that the transcription factors Twist plays an important role in hypoxia-induced EMT and renal fibrosis. Recent evidence indicates that miR-214 was regulated by Twist in many fibrotic diseases, but their role in hypoxia-induced EMT and renal fibrosis remains unknown. Here, we found that hypoxia significantly upregulated the expression of miR-214-3p in HK-2 cells, unilateral ureteral obstruction (UUO) nephropathy and patients with chronic kidney disease. Knockdown of miR-214-3p reversed the EMT of renal tubular epithelial cells (TECs) and alleviated fibrosis in the UUO mouse in vivo, while the overexpression of miR-214-3p promoted EMT phenotype and expression of fibrotic factors in TECs under hypoxic condition. In addition, Twist was also observed increased gradually with the prolongation of hypoxia, and it positively correlated with the expression of miR-214-3p in HK-2 cells transfected with Twist-overexpression or Twist-siRNA plasmid. Moreover, miR-214-3p negatively regulated the expression of epithelial cadherin (E-cadherin) by binding the E-cadherin 3′ UTR under hypoxic condition. Overall, hypoxia-induced activation of Twist/miR-214/E-cadherin axis is involved in the EMT of TECs, and anti-miR-214 may be an attractive strategy to ameliorate the progression of renal fibrosis.

60 APPLIED LIFE SCIENCES↗