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Degradation mechanism study of amine collectors in Fenton process by quantitative structure-activity relationship analysis

100%

Wang X. , Liu W. , Duan H. , Liu W.

Physicochemical Problems of Mineral Processing

2018

tom Vol. 54, iss. 3

713--721

In this study, advanced oxidation processes (AOPs), Fenton process, was applied to degrade ten amine collectors. The experimental results indicated that most of the tested amines could be removed rapidly and effectively at pH=4, while the degradation of quaternary ammonium compounds was less than others. To research the Fenton oxidation process, the degradation-rate constants of amine collectors were calculated by the pseudo-second order kinetic model, then which was used as the dependent variable to establish a quantitative structure activity relationship (QSAR) model. Meanwhile, 16 molecular structure descriptors and quantum mechanical parameters for amine collectors were simulated and analyzed by using Materials Studio software. The optimum QSAR model was established based on the partial least squares regression (PLS) method and confirmed by the statistics analysis. The model revealed that hydrogen bond acceptor (HBA) and the maximum values of electrophilic attack in C atom sites (f(-)c) were the major effect factors for the degradation-rate constants of amine collector.

Comparative study of PCR-based approaches for the genetic characterization of three strains of Acidithiobacillus caldus isolated from different sites in China

88%

Wu X. , Duan H. , Fan H. , Zhang Z. , Liu L.

nr 4

Comparative study of the genetic characteristics among three Acidithiobacillus caldus strains isolated from different typical environments in China was performed using a combination of molecular methods, namely sequencing analysis of PCR-amplified 16S rRNA genes and 16S-23S rRNA gene intergenic spacers (ITS), repetitive element PCR (rep-PCR), arbitrarily primed PCR (AP-PCR) fingerprinting and random amplified polymorphic DNA (RAPD). Both of the 16S rRNA gene and 16S-23S rRNA gene intergenic spacers sequences of the three strains exhibited small variations, with 99.9-100%, 99.7-100% identity respectively. In contrast, according to the analysis of bacterial diversity based on rep-PCR and AP-PCR fingerprinting, they produced highly discriminatory banding patterns, and the similarity values between them varied from 61.97% to 71.64%. RAPD analysis showed that banding profiles of their genomic DNA exhibited obvious differences from each other with 53.44-75% similarity. These results suggested that in contrast to 16S rRNA genes and 16S-23S rRNA gene intergenic spacers sequencing analysis, rep-PCR, AP-PCR fingerprinting and RAPD analysis possessed higher discriminatory power in identifying these closely related strains. And they could be used as rapid and highly discriminatory typing techniques in studying bacterial diversity, especially in differentiating bacteria within Acidithiobacillus caldus.

Genotypic variation of Cunninghamia lanceolata revealed by phenotypic traits and SRAP markers

88%

Zheng H. , Duan H. , Hu D. , Li Y. , Hao Y.

Dendrobiology

2015

tom 74

The success of a tree breeding program largely depended on the available genetic variability of the germplasms. Our present study aimed to assess the phenotypic variation and DNA variability using sequence-related amplified polymorphism (SRAP) markers among 50 Cunninghamia lanceolata (Chinese fir) genotypes. Extensive phenotypic variations (p < 0.05 or 0.01) were found for all the growth and wood property traits (height, diameter at breast height, stem volume, and wood basic density, hygroscopicity, heart-wood ratio, tracheid length, tracheid diameter and tracheid length-diameter ratio) with coefficients of variation spanning from 6.8 to 31.3%. At the DNA level, thirty-five SRAP primer combinations produced 498 bands with 89.4% polymorphism across genotypes; moreover, the Nei’s gene diversity was detected to be ranged between 0.204 and 0.373 (mean = 0.279), while the Shannon’s Information Index stretched from 0.324 to 0.555 with an average value of 0.427. Significance (p < 0.01) of the variability of SRAP polymorphism among genotypes was further demonstrated by AMOVA. These results indicated a relatively high level of genetic diversity in genotypes. The SRAP’ dendrogram additionally revealed that these genotypes could be split into 7 clusters with higher discriminating capacity over that of phenotype. Notably, a total of 99 statistically significant (p < 0.05) marker-trait associations related to the growth and wood property traits were identified. These marker-trait associations corresponded to 77 different SRAP markers with R2 (percentage of the phenotypic variation explained by marker) ranging from 8.3 to 26.4%.