Browsing by Author "Chen, Xin"

Now showing 1 - 6 of 6

Centralized and decentralized rumor blocking problems
(2017-07-01)
Chen, Xin
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Nong, Qingqin
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Feng, Yan
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Cao, Yongchang
;
Gong, Suning
This paper consists of two parts. In the first part, we study a centralized rumor blocking problem with a novel social objective function different from those in the literature. We will show that this objective function is non-decreasing and submodular and hence corresponding rumor blocking problem has a greedy approximation with objective function value at least of the optimal. In the second part, we study a decentralized rumor blocking problem with two selfish protectors, which falls into a 2-player non-cooperate game model. We will show that this game is a basic valid utility system and hence the social utility of any Nash equilibrium in the game is at least a half of the optimal social utility.
Clarification of lower bounds of two-machine flow-shop scheduling to minimize total late work
(2019-07-03)
Blazewicz, Jacek
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Chen, Xin
;
Lee, Richard C. T.
;
Lin, Bertrand M. T.
;
Lin, Feng-Cheng
Design and Structural Analysis of Novel Pharmacophores for Potent and Selective Peroxisome Proliferator-activated Receptor gamma Agonists
(2009-04-23)
Lin, Chia-Hui
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Peng, Yi-Hui
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Coumar, Mohane Selvaraj
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Chittimalla, Santhosh Kumar
;
Liao, Chun-Chen
Utilizing medicinal chemistry design strategies Such as benzo splitting and ring expansion, we converted PPAR alpha/gamma dual agonist 1 to selective PPAR gamma agonists 19 and 20. Compounds 19 and 20 were 2- to 4-fold better than rosiglitazone at PPAR gamma receptor. with 80- to 100-fold PPAR gamma selectivity over PPAR alpha receptor. X-ray cocrystal studies in PPAR gamma and modeling studies in PPAR alpha give molecular insights for the improved PPAR gamma potency and selectivity for 19 when compared to 1.
Polarization Engineering to Manipulate the Breakdown Voltage for GaN-Based PIN Diodes
(1970-01-01)
Hou, Xu
;
Chen, Xin
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Jia, Xingyu
;
Liu, Yajin
;
Zhang, Yonghui
This study proposes to increase the breakdown voltage for GaN-based PIN diodes using the polarization effect, such that a thin AlGaN layer is inserted into the drift layer to modulate the electric field profiles, and by properly designing the device architecture, the electric field in the drift layer can be remarkably reduced by the polarization effect, and this enables the enhancement of the breakdown voltage. The study further investigates the parametric sensitivity of the breakdown voltage for the proposed GaN-based PIN diodes to different device structures with various drift layer thicknesses. Moreover, it is found that the position of the inserted AlGaN thin layer is also important in affecting the breakdown voltage, such that the AlGaN insertion layer reduces the electric field with the maximum intensity in the drift layer.
Structural Basis for the Improved Potency of Peroxisome Proliferator-Activated Receptor (PPAR) Agonists
(2010-10-04)
Peng, Yi-Hui
;
Coumar, Mohane Selvaraj
;
Leou, Jiun-Shyang
;
Wu, Jian-Sung
;
Shiao, Hui-Yi
The need to develop safer and more effective antidiabetic drugs is essential owing to the growth worldwide of the diabetic population. Targeting the PPAR receptor is one strategy for the treatment of diabetes; the PPAR agonists rosiglitazone and pioglitazone are already on the market. Here we report the identification of a potent PPAR agonist, 15, whose PPAR gamma activation was more than 20 times better than that of rosiglitazone. Compound 15 was designed to incorporate an indole head with a carboxylic acid group, and 4-phenylbenzophenone tail to achieve a PPAR gamma EC(50) of 10 nm. Compound 15 showed the most potent PPAR gamma agonist activity among the compounds we investigated. To gain molecular insight into the improved potency of 15, a structural biology study and binding energy calculations were carried out. Superimposition of the X-ray structures of 15 and agonist 10 revealed that, even though they have the same indole head part, they adopt different conformations. The head part of 15 showed stronger interactions toward PPAR gamma; this could be due to the presence of the novel tail part 4-phenylbenzophenone, which could enhance the binding efficiency of 15 to PPAR gamma.
Structural Basis for the Improved Potency of Peroxisome Proliferator-Activated Receptor (PPAR) Agonists
(2010-10-04)
Peng, Yi-Hui
;
Coumar, Mohane Selvaraj
;
Leou, Jiun-Shyang
;
Wu, Jian-Sung
;
Shiao, Hui-Yi
The need to develop safer and more effective antidiabetic drugs is essential owing to the growth worldwide of the diabetic population. Targeting the PPAR receptor is one strategy for the treatment of diabetes; the PPAR agonists rosiglitazone and pioglitazone are already on the market. Here we report the identification of a potent PPAR agonist, 15, whose PPAR gamma activation was more than 20 times better than that of rosiglitazone. Compound 15 was designed to incorporate an indole head with a carboxylic acid group, and 4-phenylbenzophenone tail to achieve a PPAR gamma EC(50) of 10 nm. Compound 15 showed the most potent PPAR gamma agonist activity among the compounds we investigated. To gain molecular insight into the improved potency of 15, a structural biology study and binding energy calculations were carried out. Superimposition of the X-ray structures of 15 and agonist 10 revealed that, even though they have the same indole head part, they adopt different conformations. The head part of 15 showed stronger interactions toward PPAR gamma; this could be due to the presence of the novel tail part 4-phenylbenzophenone, which could enhance the binding efficiency of 15 to PPAR gamma.