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Abstract: The aim of this paper is to demonstrate possible evolutionary constraints that shape codon-pair context. The distributions of numbers of modes (DNM) of codon-pairs in protein coding sequences (CDSs) and the frequency of base triplet pairs in intergenic sequences (IGSs) are analyzed in 110 fully sequenced genomes. We propose that these distributions are in accordance with a gamma distribution. By studying the shape parameter α value of gamma distribution a distinct relation between the α value and the genome evolution is obtained. For codon-pairs in CDSs, the α value increases in the order Archaea, Bacteria, and Eukaryota, and divides the species into three evolutionary groups, Archaea, Bacteria and Eukaryota. For triplet pairs in IGSs, on the other hand, the α value classifies the species into two groups, one is Bacteria and the other is Archaea and Eukaryota. The findings suggest that the codon-pair context could be an important determinant for phylogeny of individual species, and indicate the existence of fundamental differences of evolutional constraints imposed on CDSs and IGSs among Archaea, Bacteria, and Eukaryota. [Copyright &y& Elsevier]

Triethylamine (TEA) is a mephitic volatile organic compound, which has huge damage to human body. Therefore, the development of gas sensitive materials for the effective detection of TEA has important application value. In this paper, In 2 O 3 , ErVO 4 and In 2 O 3 /ErVO 4 composite samples were successfully synthesized by hydrothermal method. The In 2 O 3 /ErVO 4 composite of In 2 O 3 and ErVO 4 has a spherical structure with a rough surface, and forms a variety of porous structures, which effectively increases the specific surface area of the composite (58.9551m2/g), thereby improving the gas sensitivity to TEA. In 2 O 3 /ErVO 4 composites can achieve a higher response to 100 ppm TEA (S = 54.73), have a lower optimal operating temperature (250 °C) compared with In 2 O 3 pure samples, and have a faster recovery time (52 s) compared with ErVO 4 pure samples. In addition, In 2 O 3 /ErVO 4 sensors also achieve good selectivity, excellent moisture resistance, long-term stability. The microstructure of the sample was significantly changed by ErVO 4 recombination. These alterations include an increase in specific surface area, a decrease in particle size, an increase in the utilization of the sensitive body, an increase in the proportion of vacancy oxygen, a decrease in the optical band gap, and an increase in electron transport efficiency. These results show that the combination of ErVO 4 and In 2 O 3 to construct heterojunction can achieve excellent sensor for TEA gas detection. [ABSTRACT FROM AUTHOR]

It is well known that two metal oxides can form depletion layers at the interface by constructing heterojunctions due to the different Fermi energy levels of each metal oxide, which can improve the carrier mobility and provide significant advantages for gas sensing. In this work, NdFeO 3 nanoparticles were grown on ZnO with hexagonal cone structure by secondary hydrothermal method to successfully construct n-ZnO/p-NdFeO 3 heterojunctions, and the crystal structures, oxygen vacancies, microstructures, optical properties, and gas-sensing properties of the ZnO/NdFeO 3 composites were investigated. The ZnO/NdFeO 3 sensors showed good ethanolamine (EA) The response characteristics of the ZnO/NdFeO 3 sensor to ethanolamine (EA) with a concentration of 100 ppm EA at 240 °C (R g /R a) is about 25, which improves the response by a factor of 1.6 and 1.32 compared with that of NdFeO3 and ZnO. Meanwhile, it has excellent selectivity, good cyclic reproducibility, and durable long-term stability with response/recovery times of 19 s/49 s. The improved EA sensing performance of NdFeO 3 -modified ZnO, in addition to its large specific surface area due to its unique rough inhomogeneous structure, is also related to the higher concentration of oxygen vacancies at the ZnO/NdFeO 3 interface after the composite. In addition, the construction of ZnO/NdFeO 3 heterostructure brings more efficient carrier migration, which is favorable to the surface reaction and diffusion of EA molecules, and lowers the ZnO operating temperature, thus reducing the energy consumption. The ZnO/NdFeO 3 composite sensor based on n-p heterojunction provides a valuable strategy for the detection of volatile organic compounds. [ABSTRACT FROM AUTHOR]