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Search Results: 1 - 10 of 32813 matches for " Mu Yuan "
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Electrostatic self-assembly Pd particles on Nafion membrane surface to reduce methanol crossover
Haolin Tang,Mu Pan,Shichun Mu,Runzhang Yuan
Chinese Science Bulletin , 2005, DOI: 10.1007/BF02897583
Abstract:
Threshold-free Evaluation of Medical Tests for Classification and Prediction: Average Precision versus Area Under the ROC Curve
Wanhua Su,Yan Yuan,Mu Zhu
Statistics , 2013,
Abstract: When evaluating medical tests or biomarkers for disease classification, the area under the receiver-operating characteristic (ROC) curve is a widely used performance metric that does not require us to commit to a specific decision threshold. For the same type of evaluations, a different metric known as the average precision (AP) is used much more widely in the information retrieval literature. We study both metrics in some depths in order to elucidate their difference and relationship. More specifically, we explain mathematically why the AP may be more appropriate if the earlier part of the ROC curve is of interest. We also address practical matters, deriving an expression for the asymptotic variance of the AP, as well as providing real-world examples concerning the evaluation of protein biomarkers for prostate cancer and the assessment of digital versus film mammography for breast cancer screening.
SYNTHESIS OF DIBENZYLBUTANEDIOL LIGNANS AND THEIR ANTI-HIV, ANTI-HSV, ANTI-TUMOR ACTIVITIES
MU XIA,YA; HUI BI,WEN; YUAN ZHANG,YUAN;
Journal of the Chilean Chemical Society , 2009, DOI: 10.4067/S0717-97072009000400023
Abstract: an effcient route to the synthesis of dibenzylbutanediol lignans and their analogues was reported. the syntheses were based on a strategy involving stobbe condensation and alkylation reaction to give the skeleton of lignan, the resolution of (±)-diacid with quinine, the transformation of functional groups to obtain seven dibenzylbutanediol lignans and one analogue. among the synthesized lignans, four compounds were natural products. all dibenzylbutanediol lignans and their analogue synthesized were evaluated on hiv tat transactivation in human epithelial cells, hsv-1 gene and human leukemic, liver, prostate, stomach, and breast cancer cell in vitro, but some compounds displayed weak activity against hiv, hsv and mda-mb-435 human breast cancer cell.
Image Hashing Algorithm Based on Robust Bits Extraction in JPEG Compression Domain
Yuan-Yuan Hu,Xia-Mu Niu
Information Technology Journal , 2010,
Abstract: Perceptual image hashing algorithm based on content-preserving property has a promising application in image retrieval and identification. By statistical analysis of the low frequency coefficients of quantized DCT blocks in JPEG compressed images, a strong correlation between the perceptual similar images is observed. The positions of the most significant low frequency coefficients are found to be invariant during common signal processings and even some geometric distortions. Based on these, a JPEG-compatible image hashing algorithm is proposed. It is verified by our experiments that the proposed algorithm not only has a strong robustness of JPEG compression (QF = 5) and common signal processings, but also is robust to geometric distortions of cropping and resize (more than 5%) and rotation (more than 3 degree), which is absent in other hashing algorithms in JPEG compression domain. Since, JPEG decoder is not needed during generating the hashing, it is more convenient and efficient for index and recognition in large image databases or the internet than those in pixel-wise domain.
SYNTHESIS OF DIBENZYLBUTANEDIOL LIGNANS AND THEIR ANTI-HIV, ANTI-HSV, ANTI-TUMOR ACTIVITIES
YA MU XIA,WEN HUI BI,YUAN YUAN ZHANG
Journal of the Chilean Chemical Society , 2009,
Abstract: An effcient route to the synthesis of dibenzylbutanediol lignans and their analogues was reported. The syntheses were based on a strategy involving Stobbe condensation and alkylation reaction to give the skeleton of lignan, the resolution of (±)-diacid with quinine, the transformation of functional groups to obtain seven dibenzylbutanediol lignans and one analogue. Among the synthesized lignans, four compounds were natural products. All dibenzylbutanediol lignans and their analogue synthesized were evaluated on HIV Tat transactivation in human epithelial cells, HSV-1 gene and human leukemic, liver, prostate, stomach, and breast cancer cell in vitro, but some compounds displayed weak activity against HIV, HSV and MDA-MB-435 human breast cancer cell.
Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) Studies on α1A-Adrenergic Receptor Antagonists Based on Pharmacophore Molecular Alignment
Xin Zhao,Minsheng Chen,Biyun Huang,Hong Ji,Mu Yuan
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12107022
Abstract: The α 1A-adrenergic receptor (α 1A-AR) antagonist is useful in treating benign prostatic hyperplasia, lower urinary tract symptoms, and cardiac arrhythmia. Three-dimensional quantitative structure-activity relationship (3D-QSAR) studies were performed on a set of α 1A-AR antagonists of N-aryl and N-nitrogen class. Statistically significant models constructed from comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were established based on a training set of 32 ligands using pharmacophore-based molecular alignment. The leave-one-out cross-validation correlation coefficients were q 2 CoMFA = 0.840 and q 2 CoMSIA = 0.840. The high correlation between the cross-validated/predicted and experimental activities of a test set of 12 ligands revealed that the CoMFA and CoMSIA models were robust ( r2pred /CoMFA = 0.694; r2pred /CoMSIA = 0.671). The generated models suggested that electrostatic, hydrophobic, and hydrogen bonding interactions play important roles between ligands and receptors in the active site. Our study serves as a guide for further experimental investigations on the synthesis of new compounds. Structural modifications based on the present 3D-QSAR results may lead to the discovery of other α 1A-AR antagonists.
On cyclic oscillation in granular gas
Tiande Miao,Yuan Liu,Fuxing Miao,Qingsong Mu
Chinese Science Bulletin , 2005, DOI: 10.1007/BF03183669
Abstract: In a Maxwell’s demon experiment on a dilute granular gas made up of two species of particles placed in two closely connected containers, a cyclic oscillation similar to the chemical oscillations is recognized that the two species of particles cluster alternately in the two containers. Then the nonlinear behavior is qualitatively explained based on a flux model.
Theoretical Foundation for the Method of Connected Local Fields
Sin-Yuan Mu;Hung-Wen Chang
PIER , 2011, DOI: 10.2528/PIER10121401
Abstract: The method of connected local fields (CLF), developed for computing numerical solutions of the two-dimensional (2-D) Helmholtz equation, is capable of advancing existing frequency-domain finite-difference (FD-FD) methods by reducing the spatial sampling density nearly to the theoretical limit of two points per wavelength. In this paper, we show that the core theory of CLF is the result of applying the uniqueness theorem to local EM waves. Furthermore, the mathematical process for computing the local field expansion (LFE) coefficients from eight adjacent points on a square is similar to that in the theory of discrete Fourier transform. We also present a theoretical analysis of both the local and global errors in the theory of connected local fields and provide closed-form expressions for these errors.
Semi-Analytical Solutions of 2-D Homogeneous Helmholtz Equation by the Method of Connected Local Fields
Hung-Wen Chang;Sin-Yuan Mu
PIER , 2010, DOI: 10.2528/PIER10092807
Abstract: The frequency-domain finite-difference (FD-FD) methods have been successfully used to obtain numerical solutions of two-dimensional (2-D) Helmholtz equation. The standard second-order accurate FD-FD scheme is known to produce unwanted numerical spatial and temporal dispersions when the sampling is inadequate. Recently compact higher-order accurate FD-FD methods have been proposed to reduce the spatial sampling density. We present a semi-analytical solution of 2-D homogeneous Helmholtz equation by connecting overlapping square patches of local fields where each patch is expanded in a set of Fourier-Bessel (FB) series. These local FB coefficients are related to total eight points, four on the sides and four on the corners, on the square patch. The local field expansion (LFE) analysis leads to an improved, compact FD-like, nine-point stencil for the 2-D homogeneous Helmholtz equation. We show that LFE formulation possesses superior numerical properties of being low dispersive and nearly isotropic because this method of connecting local fields merely ties these overlapping EM field patches already satisfy the Helmholtz equation.
5-{2-(4-Chlorophenyl)-1-[2-(4-chlorophenyl)-1-(3,4,5-trimethoxyphenyl)ethoxy]ethyl}-1,2,3-trimethoxybenzene
Ying Fu,Mu Yuan,Xuemei Hu,Yanshou Yang
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812008823
Abstract: The title compound, C34H36Cl2O7, is a by-product from the reaction of 4-chlorobenzylzinc chloride with 3,4,5-trimethoxybenzaldehyde. In each of the two 1,2-diphenylethyl moieties, the two benzene rings are arranged in a trans conformation and make Car—C—C—Car torsion angles of 163.64 (19) and 174.43 (18)°. The crystal structure is stabilized by van der Waals interactions only.
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