Applied Mechanics and Materials Vol. 618

Abstract: Half of the urea is produced by complete circulation of aqueous solution processing in China. The mixing between the gas and liquid is the key of the technology. This paper presents an improvement of the complete circulation of aqueous solution processing by premixing and atomizing liquid NH₃ and Methylamine. And a novel atomizer was developed for the high pressure and limited space. We proposed a new model based on the two innovations and predicted the performance of the suggested processing. The modeling prediction agreed well with the experimental results. For the same urea synthesis tower structure, the conversion rate increased 3~5%. This indicates this technology is competitive to retrofit the existed units.

Abstract: Vacuolar invertases play a vital role in the progress of cassava tuber roots starch accumulation. In order to study the regulating mechanism of cassava vacuolar invertases, the promoter of cassava vacuolar invertase 2 (MeVINV2) was isolated using the PCR amplification approach, starting with a part of coding sequences. Sequencing result showed that 47 bp MeVINV2 gene CDS sequence and 1242 bp potential promoter sequence was obtained. PlantCARE analysis revealed that the MeVINV2 gene promoter contains typical eukaryotic elements CAAT box and TATA box, and also several light-responsive elements and stress-responsive elements. These cis-acting regulatory elements might be associated to the vacuolar invertase gene function of cassava starch accumulation and biological stress defense.

Abstract: The present study was aimed to improve the method for detecting Mycobacterium tuberculosis complex recently reported on Letters in Applied Microbiology. Eriochrome black T (EBT) was added to the reaction system of LAMP, due to complexation of EBT with magnesium ions, the color of reaction solution was red at beginning, when the reaction was in process, the precipitate of magnesium ions and pyrophosphate ions formed, EBT lost magnesium ions, the color of reaction solution became sky blue from red gradually, and the method exhibits a high sensitivity of 8 fg/μL. The improved LAMP assay can detect Mycobacterium tuberculosis complex rapidly, sensitively and visually, the method developed in this study had solved the “bottleneck” in popularization and application of LAMP technology, which had not only avoided aerosol pollution but also solved the false positive problem caused by primer dimers.

Abstract: The effects of an arbuscular mycorrhizal fungus (AMF), Glomus mosseae, Paraglomus occultum and Glomus etunicatum, on the growth and nutrient uptake of the Prunus maritima, cultured with or without NaCl, were evaluated. Plant biomass, AM colonization and spore density were also assessed. Salt stress adversely affected plant N, Ca, Mg, Cu, Zn and Mn nutrient acquisition, except for Fe, resulting in an important reduction in shoot dry biomass. Inoculation of the AM fungus strongly promoted AM colonization and spore density, plant dry biomass, root/shoot dry weight ratio and nutrient uptake by P. maritima, regardless of salinity level. Among the three Glomus species, the total dry biomass of beach plum plants associated with G. mosseae and G. etunicatum was significantly higher than that of the control plants (48 and 43%, respectively), and so is the total leaf area (34 and 33 %, respectively). These findings suggest that inoculation with specific AMF therefore constituted an alternative method to relieve stress of soil salinization on beach plum.

Abstract: The Drosophila glial cells missing (gcm) gene is not only essential for generating embryonic glial differentiation but also necessary and sufficient for generating glial cells during the postembryonic stage. However, the mechanisms of how the gcm gene is mediated are still elusive. This study reveals that gcm was expressed with fluctuating variation during the third instar larval and pupal stage, the 20-hydroxyecdysone (20E) treatment can upregulate gcm expression, the knockdown of EcR-A and USP1 led to a reduced transcript level of gcm in S2 cells. These results suggest that the 20E signaling pathway can mediate gcm expression through the 20E receptor EcR-A and its heterodimer USP1.

Abstract: With the completion of the international HapMap project and the development of high-throughput technologies, designing more effective epistasis detection algorithm for genome-wide data poses a significant challenge. This paper proposes a new method based on the Markov blanket to solve the limitations of the existing algorithm, such as a large false-positive proportion and low accuracy. The algorithm uses G² to judge the strength of correlation between variables of self-adaptive remove strategy and SNP matching method; to effectively eliminate variables that are unrelated to the target, as well as weak correlation between variables; to significantly reduce the search space and time; to prevent unnecessary retrieval analysis; and to improve the accuracy of the detection algorithm to a certain extent.

Abstract: Ammonia-oxidizing bacteria were immobilized by sodium alginate. Immobilized conditions and ammonium removal ability of immobilized cells were researched. The results showed that the optimal immobilized conditions were: 4.5% sodium alginate with 2.0% calcium chloride, 2000 immobilized balls, 1000mL immobilized medium, pH 8, 30°C, 110r/min. Immobilized ammonia-oxidizing bacteria were recycled six times under the optimal immobilized conditions. Immobilized ammonia-oxidizing bacteria at the optimal conditions had better ammonium removal ability than non-immobilized ammonia-oxidizing and were good for preservation. Removal rate of ammonia nitrogen of immobilized ammonia-oxidizing bacteria reached 89.51%.

Abstract: A loop-mediated isothermal amplification (LAMP) method for rapid detection of various staphylococci strains and associated antibiotic resistance determinant had been developed and evaluated in this study. Six primers, including outer primers, inner primers and loop primers, were specially designed for recognizing eight distinct sequences on four targets: 16Sr RNA, femA, mecA, and orfX. Twenty-seven reference strains, including various species of gram-negative and-positive isolates, were included in this study to evaluate and optimize LAMP assays. The optimal reaction condition was found to be 65°C for 45 min, with detection limits at 100 fg DNA/tube and 10 CFU/reaction for 16S rRNA, 100 fg DNA/tube and 10 CFU/reaction for femA, 1 pg DNA/tube and 100 CFU/reaction for mecA, 10 DNA/tube and 10 CFU/reaction for orfX, respectively. Application of LAMP assays were performed on 166 various types of staphylococci isolates, the detection rate of LAMP assays for the 16Sr RNA, femA, mecA, and orfX was 100% (166/166), 98.5% (64/65), 94.3% (66/70), and 98.6% (69/70) and the negative predictive value (NPV) was 100%, 98.1%, 92.3%, and 92.7% respectively; with a 100% positive predictive value (PPV) for all three targets. In conclusion, LAMP assays were demonstrated to be useful and powerful tools for rapid detection of various staphylococci strains.

Abstract: Escherichia coli O157, Psuedomonas aeruginosa, Salmonella, Vibrio parahaemolyticus and Listeria are important pathogens for human. With increased awareness in public health, development of a rapid, sensitive, cost-effective and easy-operating bacteriological detection is of the utmost importance and urgent necessity. In this study, we developed and applied a simple amplification kit based on loop-mediated isothermal amplification (LAMP) methods for rapid detection of various pathogens including Escherichia coli O157, Psuedomonas aeruginosa, Salmonella, Vibrio parahaemolyticus and Listeria, as well as related virulence. Nine targets, including rfbE (E. coli-specific), stx1 (coding for Shiga toxin 1), stx2 (coding for Shiga toxin 2), oprI (P. aeruginosa–specific), invA (Salmonella-specific), hlyA (Listeria-specific), tlh (coding for thermolable haemolysin), tdh (coding for thermostable direct haemolysin) and trh (coding for TDH-related haemolysin), were selected for identification for Escherichia coli O157, Psuedomonas aeruginosa, Salmonella, Vibrio parahaemolyticus and Listeria, as well as related virulence.. Six primers, including outer primers, inner primers and loop primers, were specially designed for recognizing eight distinct sequences on the targets. Three solutions labeled A, B and C was included in the kit. The experiment were carried out in a total of 25 μl reaction mixture: solution A containing 1.6 μM (each) of the primers FIP and BIP, 0.2 μM (each) of the primers F3 and B3, 0.8 μM (each) of primers LF and LB; solution B containing 1.6 mM of deoxynucleoside triphosphates, 6 mM MgSO₄, 1 M betain (Sigma, St. Louis, MO, USA), 1 X thermopol buffer (New England Biolabs, Ipswich, MA, USA); solution C containing BST polymerase. Twenty-two reference strains, including various species of gram-negative and-positive isolates, were included in this study to evaluate and optimize LAMP assays. Application of the optimized LAMP assays was performed on a total of 200 strains (with 40 strains for each species of the pahtogens). The optimal reaction condition was found to be 65°C for 45 min. Application of the kit assays were performed on various types of pathogens, the sensitivity for the 9 targets was found to be 100%; with a 100% specificity and positive predictive value (PPV) for all the 9 targets targets. In conclusion, the isothermal amplification kits were demonstrated to be useful and powerful tools for rapid differentiation of various pathogens (including Escherichia coli O157, Psuedomonas aeruginosa, Salmonella, Vibrio parahaemolyticus and Listeria), and undoubtedly, the rapidness, easiness and cost-effectiveness of LAMP assay will aid in the broad application of bacteriological detection of common pathogens.

Abstract: The aim of this work was to isolate and identify antioxidant peptides from black soybean protein hydrolysates (BSH) by using the ultrafiltration (UF) and macroporous adsorption resin (MAR), and the fraction BSP-DA-c performed high antioxidant activity was further purified using consecutive methods on Sephadex G-25 column and reversed phase high-performance liquid chromatography (RH-HPLC). Two highly purified antioxidant peptides SBP3 and BSPb were got, and their amino acid sequences were confirmed as Trp-Asn-Pro and Tyr-Asn-Ile by automated Edman degradation with a protein sequencer, respectively.