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Featured Application: Automatic packaging of fruit grading production line. Automated packing is urgently needed in apple production. This paper proposes an improved genetic algorithm fused with an optimal parameter selection algorithm to optimize the two-posture manipulator working path of packing robots. First, the structure and working principle of the packing robot were designed. Second, the kinematics and packing paths of the two-posture manipulator were analyzed. Finally, the path optimization method for the two-posture manipulator was introduced. The method was based on the improved genetic algorithm by using a two-level coding and region crossover operator. The parameter values can be automatically determined by the optimal parameter selection algorithm. Ten repeated comparative tests show that the total packing time is 23.86 s under the working conditions of four grasping points and fourteen placing points. The optimal performance of the proposed algorithm is better than that of the traditional genetic algorithm, and the average optimization amplitudes are 14.63%, 15.42%, 16.24%, and 13.82% for 9-groove, 12-groove, 14-groove, and 16-groove trays, respectively. The proposed algorithm can effectively prevent the premature convergence problem of the traditional genetic algorithm and the optimization process instability problem, improve the range of optimization, and reduce the manipulator working time during packing. [ABSTRACT FROM AUTHOR]

Although straw is being utilized as an additive in construction materials, the thermal properties of straw and building materials in combination are insufficient. The thermal properties of straw–mortar composite materials can be improved by the pretreatment of straw. The alkali treatment enhances the mechanical attachment between the fibers and the matrix material, assuring that the straw–mortar composite materials have solid thermal insulation characteristics. Pretreatment with sodium hydroxide was utilized in this work to enhance the thermal properties of straw–mortar composite materials. This study mainly investigated the thermal properties of straw–mortar composite material after sodium hydroxide pretreatment and its change rules under the condition of the freeze–thaw cycle. A three-factor, three-level Box–Behnken experimental design, with the straw content (%), pretreatment time (min), and reagent concentration (%) as process parameters, was used. The response variables were the thermal conductivity, thermal diffusivity, and thermal resistance. The findings revealed that all of the variables had a substantial impact on the replies. Optimization parameters of 17.95% for the straw content, 19.50 min for the pretreatment time, and 4.99% for the reagent concentration for the straw–mortar composite materials were achieved. A thermal conductivity of 0.211 W·(m·K)−1, a thermal diffusivity of 0.277 mm2·s−1, and a thermal resistance of 57.211 K·W−1 were the optimal thermal property indices. Furthermore, during the freeze–thaw cycle, the thermal conductivity coefficient and thermal diffusion coefficient of the combined pretreatment composite were 26% and 9% lower than the materials without the treatment. The thermal performance of the mortar composites prepared by alkali-treated straw was better than that prepared by untreated straw. [ABSTRACT FROM AUTHOR]

In order to solve the low accuracy in rolling bearing fault diagnosis caused by irrelevant and redundant features, a feature selection method based on a clustering hybrid binary cuckoo search is proposed. First, the measured motor signal is processed by Hilbert–Huang transform technology to extract fault features. Second, a clustering hybrid initialization technique is given for feature selection, combining the Louvain algorithm and the feature number. Third, a mutation strategy based on Levy flight is proposed, which effectively utilizes high-quality information to guide subsequent searches. In addition, a dynamic abandonment probability is proposed based on population sorting, which can effectively retain high-quality solutions and accelerate the convergence of the algorithm. Experimental results from nine UCI datasets show the effectiveness of the proposed improvement strategy. The open-source bearing dataset is used to compare the fault diagnosis accuracy of different algorithms. The experimental results show that the diagnostic error rate of this method is only 1.13%, which significantly improves classification accuracy and effectively realizes feature dimension reduction in fault datasets. Compared to similar methods, the proposed method has better comprehensive performance. [ABSTRACT FROM AUTHOR]

Mitochondria can fuse or divide, a phenomenon known as mitochondrial dynamics, and their distribution within a cell changes according to the physiological status of the cell. However, the functions of mitochondrial dynamics during spermatogenesis in animals other than mammals and fruit flies are poorly understood. In this study, we analyzed mitochondrial distribution and morphology during spermiogenesis in Sipuncula (Phascolosoma esculenta) and investigated the expression dynamics of mitochondrial fusion-related protein MFN2 and fission-related protein DRP1 during spermiogenesis. The mitochondria, which were elliptic with abundant lamellar cristae, were mainly localized near the nucleus and distributed unilaterally in cells during most stages of spermiogenesis. Their major axis length, average diameter, cross-sectional area, and volume are significantly changed during spermiogenesis. mfn2 and drp1 mRNA and proteins were most highly expressed in coelomic fluid, a spermatid development site for male P. esculenta, and highly expressed in the breeding stage compared to in the non-breeding stage. MFN2 and DRP1 expression levels were higher in components with many spermatids than in spermatid-free components. Immunofluorescence revealed that MFN2 and DRP1 were consistently expressed and that MFN2 co-localizes with mitochondria during spermiogenesis. The results provide evidence for an important role of mitochondrial dynamics during spermiogenesis from morphology and molecular biology in P. esculenta, broadening insights into the role of mitochondrial dynamics in animal spermiogenesis. [ABSTRACT FROM AUTHOR]

The cascade catalysis of old yellow enzyme, alcohol dehydrogenase and glucose dehydrogenase has become a promising approach for one pot, two-step reduction of (E/Z)-citral to (S)-citronellol, serving as a chiral alcohol with rose fragrance. During the multi-enzymatic cascade catalysis, old yellow enzyme is responsible for the reduction of the conjugated C=C and the introduction of the chiral center, requiring high activity and (S)-enantioselectiviy. Herein, to improve the activity of the old yellow enzyme from Providencia stuartii (NemR-PS) with strict (S)-enantioselectivity, the semi-rational design on its substrate binding pocket was performed through a combination of homology modeling, molecular docking analysis, alanine scanning and iterative saturation mutagenesis. The NemR-PS variant D275G/F351A with improved activity was obtained and then purified for characterization, obeying the substrate inhibition kinetics. Compared with the wild type, the parameters Ki and Kcat/Km were increased from 39.79 mM and 2.09 s−1mM−1 to 128.50 mM and 5.01 s−1mM−1, respectively. Moreover, the variant D275G/F351A maintained strict (S)-enantioselectivity, avoiding the trade-off effect between activity and enantioselectivity. Either the enzyme NemR-PS or the variant D275G/F351A was co-expressed with alcohol dehydrogenase from Yokenella sp. WZY002 (YsADH) and glucose dehydrogenase from Bacillus megaterium (BmGDHM6). In contrast to the whole-cell biocatalyst co-expressing NemR-PS, that co-expressing the variant D275G/F351A shortened the reaction time from 36 h to 12 h in the reduction of 400 mM (E/Z)-citral. In the manner of substrate constant feeding, the accumulated product concentration reached up to 500 mM and completely eliminate the residual intermediate and by-product, suggesting the effectiveness of protein engineering and substrate engineering to improve catalytic efficiency. [ABSTRACT FROM AUTHOR]

A series of urban law enforcement events involving city inspectors dispatched by the city management department can reflect some problems in smart city management, such as illegal advertising and unlicensed street operation. In this paper, we propose a model for the allocation of city inspectors and the optimization of patrol paths. The objective is to minimize the average response time and the number of inspectors. We also develop a priority-patrol-and-multiobjective genetic algorithm (DP-MOGA) to classify patrol segments according to the frequency of events and develop an improved genetic algorithm to achieve the aforementioned objective. We conduct numerical experiments using patrol data obtained from city inspectors in Zhengzhou, China, to clearly show that the proposed algorithm generates reasonable routes that reduce the average response time of events and the number of patrol inspectors. Furthermore, we test the algorithm for three different time scenarios (roads with different average numbers of events) and demonstrate the efficiency of the algorithm. The experimental results show that our proposed algorithm is more stable and efficient than other existing algorithms. [ABSTRACT FROM AUTHOR]

Citronellol is a kind of unsaturated alcohol with rose-like smell and its (S)-enantiomer serves as an important intermediate for organic synthesis of (-)-cis-rose oxide. Chemical methods are commonly used for the synthesis of citronellol and its (S)-enantiomer, which suffers from severe reaction conditions and poor selectivity. Here, the first one-pot double reduction of (E/Z)-citral to (S)-citronellol was achieved in a multi-enzymatic cascade system: N-ethylmaleimide reductase from Providencia stuartii (NemR-PS) was selected to catalyze the selective reduction of (E/Z)-citral to (S)-citronellal, alcohol dehydrogenase from Yokenella sp. WZY002 (YsADH) performed the further reduction of (S)-citronellal to (S)-citronellol, meanwhile a variant of glucose dehydrogenase from Bacillus megaterium (BmGDHM6), together with glucose, drove efficient NADPH regeneration. The Escherichia coli strain co-expressing NemR-PS, YsADH, and BmGDHM6 was successfully constructed and used as the whole-cell catalyst. Various factors were investigated for achieving high conversion and reducing the accumulation of the intermediate (S)-citronellal and by-products. 0.4 mM NADP+ was essential for maintaining high catalytic activity, while the feeding of the cells expressing BmGDHM6 effectively eliminated the intermediate and by-products and shortened the reaction time. Under optimized conditions, the bio-transformation of 400 mM citral caused nearly complete conversion (>99.5%) to enantio-pure (S)-citronellol within 36 h, demonstrating promise for industrial application. [ABSTRACT FROM AUTHOR]