Grouping, spectrum-effect relationship and antioxidant compounds of Chinese propolis from different regions using multivariate analyses and off-line anti-DPPH assay

49 samples of propolis from different regions in China were collected and analyzed for their chemical compositions, contents of total flavonoids (TFC), total phenolic acid (TPC) and antioxidant activity. High-performance liquid chromatography (HPLC) analysis identified 15 common components, including key marker compounds pinocembrin, 3-O-acetylpinobanksin, galangin, chrysin, benzyl p-coumarate, pinobanksin and caffeic acid phenethyl ester (CAPE). Cluster analysis (CA) and correlation coefficients (CC) analysis showed that these propolis could be divided into three distinct groups. Principal component analysis (PCA) and multiple linear regression analysis (MLRA) revealed that the contents of isoferulic acid, caffeic acid, CAPE, 3,4-dimethoxycinnamic acid, chrysin and apigenin are closely related to the antioxidant properties of propolis. In addition, eight peak areas decreased after reacting with 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radicals, indicating that these compounds have antioxidant activity. The results indicate that the grouping and spectrum-effect relationship of Chinese propolis are related to their chemical compositions, and several compounds may serve as a better marker for the antioxidant activity of Chinese propolis than TFC and TPC. The findings may help to develop better methods to evaluate the quality of propolis from different geographic origins

Morphology, internal architectures and formation mechanisms of mega-pockmarks on the northwestern South China Sea margin

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Water Resources Contribution To Economic Growth In Erdos City: Model And Demonstration

Erdos City has been one of the fastest growing economic regions in China in the past twenty years, whose average annual economic growth rate has exceeded 20%. However, water resources shortage is becoming increasingly significant in constraint on social development and has gradually developed to be one of primary weakest factors. Based on the analysis of main factors promoting economic growth in Erdos City with Cobb-Douglas production function in economics, the economic growth model involving water resources availability and coal output has been established and the data conversion method considering water consumption efficiency and water consumption structural change has been proposed. In this way, it has made up for the deficiency of failing to fully consider the contribution of water consumption efficiency improvement and water consumption structural change to economic growth in the past researches. What have been discovered in the simulation and analysis of water resources contribution to economic growth in Erdos City from 1980 to 2010 as follows: (1) Water resources average contribution rate to economic growth in Erdos City in the past 30 years is 8.26%; (2) Consumption efficiency and structural change of water resources have played an important role in promoting economic development; (3) Water resources contribution to economic growth has shown a gradually increasing trend that the average contribution rates in the three decades are 1.87%, 9.69% and 10.09% respectively. The trend is closely connected with constantly increased gross water consumption, obvious improvement of water consumption efficiency and gradual upgrading of water consumption structure in the local area. It also has reflected that water resources have played an increasingly significant role in constraint on regional economic social development

On Skew Circulant Type Matrices Involving Any Continuous Fibonacci Numbers

Circulant and skew circulant matrices have become an important tool in networks engineering. In this paper, we consider skew circulant type matrices with any continuous Fibonacci numbers. We discuss the invertibility of the skew circulant type matrices and present explicit determinants and inverse matrices of them by constructing the transformation matrices. Furthermore, the maximum column sum matrix norm, the spectral norm, the Euclidean (or Frobenius) norm, and the maximum row sum matrix norm and bounds for the spread of these matrices are given, respectively

Determinants, Norms, and the Spread of Circulant Matrices with Tribonacci and Generalized Lucas Numbers

Circulant matrices play an important role in solving ordinary and partial differential equations. In this paper, by using the inverse factorization of polynomial of degree n, the explicit determinants of circulant and left circulant matrix involving Tribonacci numbers or generalized Lucas numbers are expressed in terms of Tribonacci numbers and generalized Lucas numbers only. Furthermore, four kinds of norms and bounds for the spread of these matrices are given, respectively

Isomorphic Operators and Functional Equations for the Skew-Circulant Algebra

The skew-circulant matrix has been used in solving ordinary differential equations. We prove that the set of skew-circulants with complex entries has an idempotent basis. On that basis, a skew-cyclic group of automorphisms and functional equations on the skew-circulant algebra is introduced. And different operators on linear vector space that are isomorphic to the algebra of n×n complex skew-circulant matrices are displayed in this paper

Isomorphic Operators and Functional Equations for the Skew-Circulant Algebra

The skew-circulant matrix has been used in solving ordinary differential equations. We prove that the set of skew-circulants with complex entries has an idempotent basis. On that basis, a skew-cyclic group of automorphisms and functional equations on the skew-circulant algebra is introduced. And different operators on linear vector space that are isomorphic to the algebra of × complex skew-circulant matrices are displayed in this paper

Gaussian Fibonacci Circulant Type Matrices

Circulant matrices have become important tools in solving integrable system, Hamiltonian structure, and integral equations. In this paper, we prove that Gaussian Fibonacci circulant type matrices are invertible matrices for n>2 and give the explicit determinants and the inverse matrices. Furthermore, the upper bounds for the spread on Gaussian Fibonacci circulant and left circulant matrices are presented, respectively