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Solving high-temperature plastic mulching film-induced leaf burning in the first week during tobacco cultivation would take much time and effort. In the present study, the growth as well as the leaf sugar and nicotine contents of seedlings with or without leaf burning induced by high-temperature plastic mulching film were tested at two independent sites in 2015 and 2016 to identify the influence of leaf burning on seedling growth. The results showed that the growth of seedlings with leaf burning was improved with increased leaf area, leaf number and plant height compared to those without leaf burning, combined with an increased seedling survival rate at two sites in two years. In seedlings with leaf burning, the contents of fructose and glucose increased and peaked at 11:00 and 13:00 in the leaf and root, respectively, with an increased root nicotine content beginning at 13:00, highlighting the signalling role of sugars. Activities of antioxidant enzymes including peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) were all increased in seedlings with leaf burning. More plant biomass was allocated to roots in seedlings with leaf burning with increased root volume compared to control seedlings, which might facilitate the absorption of water and nutrients from the soil. Our findings demonstrate that high-temperature plastic mulching film-induced leaf burning not inhibited but benefited seedling survival and growth, suggesting that the time and labour-consuming manual plucking of burnt leaves can be avoided during tobacco cultivation.

AIM: To compare the results of axial length (AL) biometry in cataract eyes by three methods: immersion B-ultrasound (IB) biometry, immersion A-ultrasound (IA) biometry and optical low coherence reflectometry. METHODS: In this prospective observational study of eyes with cataract AL measurements were performed using immersion ultrasound and optical low coherence reflectometry device. The results were evaluated using Bland-Altman analyses. The differences between both methods were assessed using the paired t-test, and its correlation was evaluated by Pearson coefficient. RESULTS: Eighty eyes of 80 patients (39 men and 41 women) for cataract surgery were included in the study. The values of AL could be got from all 80 eyes by IB and IA, the difference of AL measurements between IA and IB was of no statistical significance (P=0.97); the mean difference in AL measurements was -0.031 mm (P=0.26; 95%CI, -0.09 to 0.02); linear regression showed an excellent correlation (r=0.98, P

The trehalose (Tre) pathway has strong effects on growth and development in plants through regulation of carbon metabolism. Altering either Tre or trehalose 6-phosphate (T6P) can improve growth and productivity of plants as observed under different water availability. As yet, there are no reports of the effects of modification of Tre orT6P on plant performance under limiting nutrition. Here we report that nitrogen (N) metabolism is positively affected by exogenous application of Tre in nitrogen-deficient growing conditions. Spraying foliage of tobacco (Nicotiana tabacum) with trehalose partially alleviated symptoms of nitrogen deficiency through upregulation of nitrate and ammonia assimilation and increasing activities of nitrate reductase (NR), glycolate oxidase (GO), glutamine synthetase (GS) and glutamine oxoglutarate aminotransferase (GOGAT) with concomitant changes in ammonium (NH4 +) and nitrate (NO3 −) concentrations, glutamine and amino acids. Chlorophyll and total nitrogen content of leaves and rates of photosynthesis were increased compared to nitrogen-deficient plants without applied Tre. Total plant biomass accumulation was also higher in Tre -fed nitrogen-deficient plants, with a smaller proportion of dry weight partitioned to roots, compared to nitrogen-deficient plants without applied Tre. Consistent with higher nitrogen assimilation and growth, Tre application reduced foliar starch. Minimal effects of Tre feeding were observed on nitrogen-sufficient plants. The data show, for the first time, significant stimulatory effects of exogenous Tre on nitrogen metabolism and growth in plants growing under deficient nitrogen. Under such adverse conditions metabolism is regulated for survival rather than productivity. Application of Tre can alter this regulation towards maintenance of productive functions under low nitrogen. This has implications for considering approaches to modifying the Tre pathway for to improve crop nitrogen-use efficiency and production.

Based on the method of power bond graph, the simulation model of the hydraulic system of the hydraulic breaker is presented. Treanor’s numerical method is applied to calculate the dynamic response of the hydraulic breaker in time domain. The dynamic Characteristics of the piston and the spool is achieved. The influence regularity of the working parameters on the performance of hydraulic breaker is shown.

Based on virtual modeling technology and multi-body dynamics theory, three-dimensional virtual design and dynamics simulation was completed in this paper. Basic flow and general method of layout design of product using of 3D computer aided design software was presented. The frame model of layout was completed based on the structure and performance requirements of the dual-side-load trailer and 3D software’s CAD technology including parametric and variational technology and top-down design method. Based on the frame model, the layout design of the trailer was completed and the three-dimensional digital model was established. Took the lifting mechanism of the trailer as an example, based on its structure and operation principle, kinematics and dynamics simulation to each of the typical operation processes was completed.

The stress distribution of an S-shaped micro spring fabricated by the micro-electro-mechanical-system (MEMS) technology was analyzed by the finite-element method (FEM) using ANSYS software, which showed that the stress concentration is located in the inner corner of the turning round. To reduce the maximum stress but not change the spring coefficient, an optimization S-shaped micro spring with the slope cross section was designed. The width of one end of the turning round is increased from the original 80μm to 100μm, while the other is decreased from 80μm to 21.5μm. The spring coefficient formula of the optimization S-shaped micro spring was calculated out by the Castigliano second law, and the difference between the formula and the FEM is 2.7%. At the same time the FEM simulation shows that the maximum stress of the optimization S-shaped micro spring can be reduced by 32.7% while the spring coefficient is the same comparing with the primary S-shaped micro spring, which shows that the mechanical performance of the optimization S-shaped micro spring is better than that of the primary S-shaped micro spring.

Two new triterpenoid saponins, named cernuaside C and D, have been isolated from Pulsatilla cernua (Thunb.) Bercht. et Opiz. The structures of the two new triterpenoid saponins were elucidated as 3-O-beta-D-xylopyranosyl(1 --2)-[alpha-L-rhamnopyranosyl(1 --3)]-alpha-L-arabinopyranosyl oleanolic acid 28-alpha-L-rhamnopyranosyl(1 --4)-beta-D-glucopyranosyl(1 --6)-beta-D-glucopyranoside. (1) and 3-O-alpha-L-arabinopyranosyl (1 --3)-alpha-L-rhamnopyranosyl(1 --2)-alpha-L-arabinopyranosyl oleanolic acid 28-O-beta-D-glucopyranoside (2) by 1D, 2D-NMR techniques, ESI-MS analysis as well as chemical methods.

To identify genes that are differentially expressed in tobacco in response to environmental changes and to decipher the mechanisms by which aromatic carotenoids are formed in tobacco, an Agilent Tobacco Gene Expression microarray was adapted for transcriptome comparison of tobacco leaves derived from three cultivated regions of China, Kaiyang (KY), Weining (WN) and Tianzhu (TZ). A total of 1,005 genes were differentially expressed between leaves derived from KY and TZ, 733 between KY and WN, and 517 between TZ and WN. Genes that were upregulated in leaves from WN and TZ tended to be involved in secondary metabolism pathways, and included several carotenoid pathway genes, e.g., NtPYS, NtPDS, and NtLCYE, whereas those that were down-regulated tended to be involved in the response to temperature and light. The expression of 10 differentially expressed genes (DEGs) was evaluated by real-time quantitative polymerase chain reaction (qRT-PCR) and found to be consistent with the microarray data. Gene Ontology and MapMan analyses indicate that the genes that were differentially expressed among the three cultivated regions were associated with the light reaction of photosystem II, response to stimuli, and secondary metabolism. High-performance liquid chromatography (HPLC) analysis showed that leaves derived from KY had the lowest levels of lutein, β-carotene, and neoxanthin, whereas the total carotenoid content in leaves from TZ was greatest, a finding that could well be explained by the expression patterns of DEGs in the carotenoid pathway. These results may help elucidate the molecular mechanisms underlying environmental adaptation and accumulation of aroma compounds in tobacco.