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1. Sampling via Rejection-Free Partial Neighbor Search

Author

Chen, Sigeng, Rosenthal, Jeffrey S., Dote, Aki, Tamura, Hirotaka, and Sheikholeslami, Ali

Subjects
Statistics - Computation
Abstract

The Metropolis algorithm involves producing a Markov chain to converge to a specified target density $\pi$. In order to improve its efficiency, we can use the Rejection-Free version of the Metropolis algorithm, which avoids the inefficiency of rejections by evaluating all neighbors. Rejection-Free can be made more efficient through the use of parallelism hardware. However, for some specialized hardware, such as Digital Annealing Unit, the number of units will limit the number of neighbors being considered at each step. Hence, we propose an enhanced version of Rejection-Free known as Partial Neighbor Search, which only considers a portion of the neighbors while using the Rejection-Free technique. This method will be tested on several examples to demonstrate its effectiveness and advantages under different circumstances., Comment: 34 pages and 11 figures

Published
2022

2. Optimization via Rejection-Free Partial Neighbor Search

Author

Chen, Sigeng, Rosenthal, Jeffrey S., Dote, Aki, Tamura, Hirotaka, and Sheikholeslami, Ali

Subjects
Mathematics - Optimization and Control, Statistics - Methodology
Abstract

Simulated Annealing using Metropolis steps at decreasing temperatures is widely used to solve complex combinatorial optimization problems. In order to improve its efficiency, we can use the Rejection-Free version of the Metropolis algorithm, which avoids the inefficiency of rejections by considering all the neighbors at every step. As a solution to avoid the algorithm from becoming stuck in local extreme areas, we propose an enhanced version of Rejection-Free called Partial Neighbor Search (PNS), which only considers random parts of the neighbors while applying Rejection-Free. We demonstrate the superior performance of the Rejection-Free PNS algorithm by applying these methods to several examples, such as the QUBO question, the Knapsack problem, the 3R3XOR problem, and the quadratic programming., Comment: 24 pages with 2 more pages of reference, 9 figures

Published
2022

31. Characterization of SrFe0.9‐xCuxMo0.1O3‐δ (x = 0, 0.1 and 0.2) as cathode for intermediate‐temperature solid oxide fuel cells.

Author

Yao, Chuangang, Yang, Jixing, Zhang, Haixia, Chen, Sigeng, Meng, Jian, and Cai, Kedi

Subjects
SOLID oxide fuel cells, CATHODES, ACTIVATION energy
Abstract

Summary: Cu doped perovskites SrFe0.9‐xCuxMo0.1O3‐δ (SFCM, x = 0‐0.2) are explored as cathodes for IT‐SOFCs. The influence of Cu doping on the property of SFCM series was studied in detail. The oxygen content decreases with the increase of Cu doping amount. SFCM samples are chemically compatible with LSGM electrolyte. However, the TEC values are still a bit higher than that of some common SOFC electrolytes. At 750°C, the Rp values are 0.261, 0.227 and 0.155 Ω·cm2 for SFCM0, SFCM0.1, and SFCM0.2. The obtained activation energies for x = 0, 0.1, and 0.2 are 1.01, 0.98, and 0.87 eV, respectively. These results indicate that Cu doping into SrFe0.9‐xCuxMo0.1O3‐δ has a favorable effect on the electrochemical activity of the materials. [ABSTRACT FROM AUTHOR]

Published
2021
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41. Immunodetection of serum albumin adducts as biomarkers for organophosphorus exposure.

Author

Chen, Sigeng, Zhang, Jun, Lumley, Lucille, and Cashman, John R

Abstract

A major challenge in organophosphate (OP) research has been the identification and utilization of reliable biomarkers for the rapid, sensitive, and efficient detection of OP exposure. Although Tyr 411 OP adducts to human serum albumin (HSA) have been suggested to be one of the most robust biomarkers in the detection of OP exposure, the analysis of HSA-OP adduct detection has been limited to techniques using mass spectrometry. Herein, we describe the procurement of two monoclonal antibodies (mAb-HSA-GD and mAb-HSA-VX) that recognized the HSA Tyr 411 adduct of soman (GD) or S-[2-(diisopropylamino)ethyl]-O-ethyl methylphosphonothioate (VX), respectively, but did not recognize nonphosphonylated HSA. We showed that mAb-HSA-GD was able to detect the HSA Tyr 411 OP adduct at a low level (i.e., human blood plasma treated with 180 nM GD) that could not be detected by mass spectrometry. mAb-HSA-GD and mAb-HSA-VX showed an extremely low-level detection of GD adducted to HSA (on the order of picograms). mAb-HSA-GD could also detect serum albumin OP adducts in blood plasma samples from different animals administered GD, including rats, guinea pigs, and monkeys. The ability of the two antibodies to selectively recognize nerve agents adducted to serum albumin suggests that these antibodies could be used to identify biomarkers of OP exposure and provide a new biologic approach to detect OP exposure in animals.

Published
2013
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42. Hepatitis B Virus X Protein Differentially Regulates Cell Cycle Progression in X-transforming VersusNontransforming Hepatocyte (AML12) Cell Lines*

Author

Lee, Sook, Tarn, Chi, Wang, Wen-Horng, Chen, Sigeng, Hullinger, Ronald L., and Andrisani, Ourania M.

Abstract

Hepatitis B virus (HBV) X protein (pX) is implicated in hepatocarcinogenesis of chronically infected HBV patients. To understand mechanism(s) of pX-mediated cellular transformation, we employed two tetracycline-regulated, pX-expressing cell lines, constructed in AML12 immortalized hepatocytes: one a differentiated (3pX-1) and the other a de-differentiated (4pX-1) hepatocyte cell line. Only 3pX-1 cells undergo pX-mediated transformation, via sustained Ras-Raf-mitogen-activated protein kinase pathway activation. pX-nontransforming 4pX-1 cells display sustained, pX-dependent JNK pathway activation. To understand how pX mediates different growth characteristics in 3pX-1 and 4pX-1 cells, we report, herein, comparative cell cycle analyses. pX-transforming 3pX-1 cells display pX-dependent G1, S, and G2/M progression evidenced by cyclin D1, A, and B1induction, and Cdc2 kinase activation. pX-nontransforming 4pX-1 cells display pX-dependent G1and S phase entry, followed by S phase pause and absence of Cdc2 kinase activation. Interestingly, 4pX-1 cells exhibit selective pX-induced expression of cyclin-dependent kinase inhibitor p21Cip1, tumor suppressor p19ARF, and proapoptotic genesbaxand IGFBP-3. Despite the pX-mediated induction of growth arrest and apoptotic genes and the absence of pX-dependent Cdc2 activation, 4pX-1 cells do not undergo pX-dependent G2/M arrest or apoptosis. Nocodazole-treated, G2/M-arrested 4pX-1 cells exhibit pX-dependent formation of multinucleated cells, similar to human T-cell lymphotropic virus type I Tax-expressing cells. We propose that in 4pX-1 cells, pX deregulates the G2/M checkpoint, thus rescuing cells from pX-mediated apoptosis.

Published
2002
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43. Evaluation of A-site Ba-deficient PrBa0.5-xSr0.5Co2O5+δ (x = 0, 0.04 and 0.08) as cathode materials for solid oxide fuel cells.

Author

Yao, Chuangang, Yang, Jixing, Zhang, Haixia, Chen, Sigeng, Lang, Xiaoshi, Meng, Jian, and Cai, Kedi

Subjects
*SOLID oxide fuel cells, *ELECTRIC conductivity, *CATHODES, *CARBON dioxide, *THERMAL expansion
Abstract

• Ba-deficient PrBa 0.5- x Sr 0.5 Co 2 O 5+ δ perovskites were studied as IT-SOFC cathode. • Introduction of Ba deficiency promotes the formation of oxygen vacancies. • PB 0.5- x SCO oxides have good chemical compatibility with LSGM electrolyte. • Ba deficiency is beneficial to the electrochemical performance of PB 0.5- x SCO. Ba-deficient PrBa 0.5- x Sr 0.5 Co 2 O 5+ δ (PB 0.5- x SCO, x = 0, 0.04 and 0.08) perovskites are synthesized. The effects of Ba deficiency on the phase structure, thermal expansion, electrical and electrochemical characteristics of PB 0.5- x SCO are investigated. PB 0.5- x SCO samples are chemically compatible with LSGM electrolyte at 1000 °С. Slightly decrement of TECs with the rise of Ba deficiency content in PB 0.5- x SCO is observed. The introduction of Ba deficiency promotes the formation of additional oxygen vacancies, which is responsible for the decrement of electrical conductivity and improvement of electrochemical performance of PB 0.5- x SCO samples. The electrical conductivity is higher than 580 Scm−1 for PB 0.5- x SCO perovskites within 50–800 °C. The electrochemical performance is promoted significantly by introducing Ba deficiency in PB 0.5- x SCO. The ASRs of the Ba-deficient PB 0.5- x SCO decreased by more than 60% in comparison with the sample without Ba-deficiency, indicating the introduction of Ba deficiency is an effective way to improve the electrochemical characteristic of PB 0.5- x SCO cathodes. [ABSTRACT FROM AUTHOR]

Published
2021
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