Research on Key Quality Characteristics of Electromechanical Product Based on Meta-Action Unit

Electromechanical products have many quality characteristics, representing their quality. In addition, there are long-existed quality problems of electromechanical products, such as poor accuracy, short precision life, large fluctuations in performance, frequently failing, and so on. Based on meta-action unit (MU) for electromechanical products, this book chapter proposes a key quality characteristic control method, which provides theoretical and technical support for essentially guaranteeing the complete machine’s quality. The formation mechanisms of MU’s four key quality characteristics (precision, precision life, performance stability, and reliability) are studied. Moreover, we introduce an overview of key quality characteristic control methods based on MU. The complex large system research method of “decomposition-analysis-synthesis” is adopted to study these key science problems

A new Agkistrodon halys venom-purified protein C activator prevents myocardial fibrosis in diabetic rats

Aim To assess the effects of protein C activator (PCA) from Agkistrodon halys snake venom on cardiac fibrosis in streptozotocin (STZ) induced diabetic rat model, and investigate the mechanisms of its action. Methods PCA was identified by one-dimensional reversed phase liquid chromatography – mass spectrometry/mass spectrometry. Male Sprague-Dawley rats (120-140 g) were randomly assigned to negative control (NC) and diabetic group. Diabetes was induced by STZ in high-fat diet fed rats. Diabetic group was subdivided into three groups: diabetic group (DM), diabetic group treated with PCA (0.5, 2, and 8 mg/kg), and diabetic group treated with metformin (5 mg/kg, positive control). NC and DM groups received the same volume of distilled water. Left ventricular mass index (LVWI) and collagen volume fraction were measured by hematoxylin and eosin and Masson staining. Transforming growth factor beta-1 (TGF-β1) and interleukin 1 beta (IL-1β) levels were determined by enzyme-linked immunosorbent assay. Results The diabetic rat model was successfully established by STZ induction and high-fat diet. Glucose level, LVWI, TGF-β1 and IL-1β level, and collagen volume fraction were significantly reduced in diabetic rats treated by PCA in a dose-dependent manner (P < 0.050), especially in the high dose (8 mg/kg) group (P < 0.010), compared to diabetes group. The high dose PCA had the same effect as metformin positive control in reducing the level of fasting blood glucose. PCA decreased the expression of MMP-2 and reduced that of TIMP-2. Conclusion Our results indicate that PCA has anti-fibrotic effects and that it may be used to treat myocardial fibrosis

Submerged vegetation removal promotes shift of dominant phytoplankton functional groups in a eutrophic lake

Historical data indicate that the dominance of submerged plants in Dianchi Lake in the 1960s was characterized by low algal density with dominance of non-toxic group J (Scenedesmus, Pediastrum, etc.). The removal of submerged plants, which began in the 1970s, resulted in the expansion of bloom-forming Microcystis (group M). Laboratory experiments suggested that Microcystis aeruginosa was inclined to grow and develop at elevated temperatures. The growth of Scenedesmus obliquus was slower than that of co-cultivated M. aeruginosa in the absence of Ceratophyllum demersum, especially at higher temperatures. The existence of submerged plant C. demersum could inhibit the growth of the harmful algae M. aeruginosa and this inhibitory effect by C. demersum was enhanced with an increase in temperature. Instead, with C. demersum, the growth of S. obliquus was not inhibited, but the co-cultivated M. aeruginosa was eliminated in a short time. Combined with the historical data and laboratory experiments, it was indicated that the submerged plants might play important roles in the dominance of the non-toxic group J in the historical succession. Consequently, the introduction of the submerged plant such as C. demersum might alter the dominant phytoplankton functional groups from M to J and benefit the restoration of the eutrophic lake. (C) 2014 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V

Responses of phytoplankton functional groups to simulated winter warming

We investigated the seasonal dynamics of phytoplankton functional groups and the relevant environmental factors (water temperature, total nitrogen content, total phosphorous content and water transparency) in Dianchi Lake, China. We also examined the growth rates and physiological characteristics of representative species in laboratory cultures. In the field experiment, five dominant functional groups, including M (mainly consisted of Microcystis aeruginosa; Microcystis wesenbergii and Microcystis flos-aquae), H1(mainly consisted of Aphanizomenon flos-aquae), J (mainly consisted of Scenedesmus; Pediastrum and Coelastrum), F (mainly consisted of Oocystis and Kirchneriella) and P (mainly consisted of Melosira), were determined. Groups M and J were prevalent throughout the year and comprised more than 90% of the total biomass. Group M was prevalent at a relatively high temperature in summer and autumn; by contrast, group J was dominant at low temperature in winter and early spring. Co-cultivation laboratory experiments revealed that the biomass and the density of Microcystis sp., which is the representative species of the functional group M, were higher at 18 degrees C than at 13 degrees C. Conversely, the density and the biomass of the representative species of the functional group J (consisted of Pediastrum duplex, Coelastrum microporum and Scenedesmus obliquus) were higher at 13 degrees C than at 18 degrees C. At low temperatures, group M (Microcystis spp.) cannot successfully survive and grow at low temperatures, exhibiting various stress responses, such as inhibited photosynthetic activities and reduced phosphorous utilization. However, low temperature increased soluble carbohydrate contents of Microcystis, which favored the fast development of Microcystis, once the temperature warmed. Currently, climate warming is occurring in the Dianchi Lake basin; thus, future climate warming in winter (+/- 5 degrees C) may compromise the advantages of group J and promote the abundance of group M. The water transparency, dissolved oxygen and biodiversity in the lake would be further reduced. Furthermore, the increased microcystin and odor produced by Microcystis would considerably threaten the food web structure and lake ecosystem functions

Physiological changes of submerged macrophytes in response to a floating filamentous green algae bloom in clear-water conditions

The aim of this study was to evaluate the physiological responses of a submerged macrophyte to a floating filamentous green algal bloom in clear-water conditions. Elodea nuttallii was grown with floating Cladophora sp. at four different levels (0, control; 140, 280, 560 g FW/m(2)) in an outdoor experimental system, and its photosynthetic and antioxidant systems were evaluated. The presence of floating Cladophora sp. significantly changed the water environment by decreasing light intensity and increasing dissolved oxygen and the pH value. The photosynthetic parameters of E. nuttallii (e.g. Delta F/F-m&#39;,F-v/F-m, total chlorophyll) were higher in the presence of floating Cladophora sp. than in the control at the beginning of experiment. Because of the increasing dissolved oxygen concentration and pH value, the values of these indicators decreased (except for photosynthetic pigments) during the experiment. Compared with E. nuttallii in the control, E. nuttallii growing in the presence of floating Cladophora sp. showed higher malondialdehyde content, catalase activity, and peroxidase activity. The biomass of E. nuttallii was decreased by about 30% in the presence of high biomasses of floating Cladophora sp. (280 and 560 g FW/m(2)). These results suggest that floating Cladophora had complex effects on the biomass of E. nuttallii and that changes in water quality resulting from floating Cladophora sp. may be more important than its direct shading effect.</p

Submerged vegetation removal promotes shift of dominant phytoplankton functional groups in a eutrophic lake

Historical data indicate that the dominance of submerged plants in Dianchi Lake in the 1960s was characterized by low algal density with dominance of non-toxic group J (Scenedesmus, Pediastrum, etc.). The removal of submerged plants, which began in the 1970s, resulted in the expansion of bloom-forming Microcystis (group M). Laboratory experiments suggested that Microcystis aeruginosa was inclined to grow and develop at elevated temperatures. The growth of Scenedesmus obliquus was slower than that of co-cultivated M. aeruginosa in the absence of Ceratophyllum demersum, especially at higher temperatures. The existence of submerged plant C. demersum could inhibit the growth of the harmful algae M. aeruginosa and this inhibitory effect by C. demersum was enhanced with an increase in temperature. Instead, with C. demersum, the growth of S. obliquus was not inhibited, but the co-cultivated M. aeruginosa was eliminated in a short time. Combined with the historical data and laboratory experiments, it was indicated that the submerged plants might play important roles in the dominance of the non-toxic group J in the historical succession. Consequently, the introduction of the submerged plant such as C. demersum might alter the dominant phytoplankton functional groups from M to J and benefit the restoration of the eutrophic lake. (C) 2014 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V

Distribution and population dynamics of potential anatoxin-a-producing cyanobacteria in Lake Dianchi, China

The occurrence of cyanobacterial blooms is often accompanied by a variety of toxic secondary metabolites known as cyanotoxins. Anatoxin-a (ATX-a) is a highly toxic cyanobacterial neurotoxin synthesized by numerous species (e.g., Aphanizomenon, Anabaena and Oscillatoria) that has received much public attention. In this study, we used molecular methods (PCR and qPCR) to track the presence and dynamics of ATX-a-producing cyanobacteria, Aphanizomenon and Anabaena in Lake Dianchi, China based on the anaC and cpcBA-IGS genes over a 23-month period (from June 2010 to April 2012). Results revealed that Aphanizomenon was the major potential ATX-a producer in Lake Dianchi and that they were most abundant in early spring and least abundant in summer, coinciding with observed Aphanizomenon blooms. It was found that the proportion of ATX-a toxigenic cells was lower in the northern part of the lake (2.1%) than the middle (16.7%) and southern parts (19.2%). The information on the spatio-temporal distributions of ATX-a-producing cyanobacteria obtained in this study will help to build management strategies to improve water quality for public health. (C) 2015 Elsevier B.V. All rights reserved

Research summary of the usability of CNC machine tools

The usability of CNC machine tools is a comprehensive reflection of reliability, maintainability and supportability, which is also a feature that users concern about mostly. It is affected not only by the function failures of CNC machine tools, but also by the performance failures, such as precision degradation, performance fluctuation, oil leakage and so on. So separated research on reliability is not enough to maintain the "usable and easy-to-use state" of domestic CNC machine tools. The present situation and research significance of domestic CNC machine tools' usability are analyzed. The research status of usability modeling method and maintenance decision method at home and abroad are expounded. Then the problems and developments existing in usability research of CNC machine tools are summarized. Finally, the understanding of two key scientific problems in urgent need of research are put forward, including systematic modeling for the usability based on meta-action unit and active maintenance decision centered on usability of CNC machine tools, which might provide ideas for the usability research of CNC machine tools