Design and Research of Active Gravity Unloading Device for Large Aperture Optical Mirror

The large aperture optical mirror for space is processed and tested in the gravity environment on the ground. After entering space, gravity disappears due to the change of environment, and the mirror surface that has met the engineering requirements on the ground will change, seriously affecting the imaging quality. In order to eliminate the influence of gravity and to ensure the consistency of space and ground, gravity unloading must be performed. In order to meet the requirements of processing and testing for the large aperture space mirror in the state of vertical optical axis, a universal gravity unloading device was proposed. It was an active support and used air cylinders to provide accurate unloading force. First, the design flow of gravity unloading was introduced;then the detailed design of the mechanical structure and control system was given;then the performance parameters of the two types of cylinders were tested and compared, including the force-pressure relationship curve and the force-position relationship curve;finally, the experimental verification of the gravity unloading device was carried out;for a mirror with an aperture of ?2100 mm, the gravity unloading device was designed and a vertical detection optical path was built. The test results showed that by using this gravity unloading device, the actual processing surface accuracy of the mirror was better than 1/50λ-RMS, which met the application requirement of the optical system. Thus, it can be seen that using this gravity unloading device can effectively unload the gravity of the mirror and realize the accurate processing and measurement of the mirror surface. .

Chemoselective Transfer Hydrogenation of Cinnamaldehyde over Activated Charcoal Supported Pt/Fe3O4 Catalyst

A variety of spherical and structured activated charcoal supported Pt/Fe3O4 composites with an average particle size of ~100 nm have been synthesized by a self-assembly method using the difference of reduction potential between Pt （Ⅳ） and Fe （Ⅱ） precursors as driving force. The formed Fe3O4 nanoparticles （NPs） effectively prevent the aggregation of Pt nanocrystallites and promote the dispersion of Pt NPs on the surface of catalyst, which will be favorable for the exposure of Pt active sites for high-efficient adsorption and contact of substrate and hydrogen donor. The electron-enrichment state of Pt NPs donated by Fe304 nanocrystallites is corroborated by XPS measurement, which is responsible for promoting and activating the terminal C=O bond of adsorbed substrate via a vertical configuration. The experimental results show that the activated charcoal supported Pt/Fe3O4 catalyst exhibits 94.8% selectivity towards cinnamyl alcohol by the transfer hydrogenation of einnamaldehyde with Pt loading of 2.46% under the optimum conditions of 120 ℃ for 6 h, and 2-propanol as a hydrogen donor. Additionally, the present study demonstrates that a high-efficient and recyclable catalyst can be rapidly separated from the mixture due to its natural magnetism upon the application of magnetic field.

School and community physical activity characteristics and moderate-to-vigorous physical activity among Chinese school-aged children： A multilevel path model analysis

Purpose: The purpose of this study was to examine the association between school and community physical activity(PA) characteristics and levels of moderate-to-vigorous physical activity(MVPA) among Chinese school children.Methods: Data were obtained from the 2016 Physical Activity and Fitness in China—The Youth Study project. Participants were 80,928 school children(Grades 4–12; 39,747 boys, 41,181 girls; mean age = 13 years) and 935 physical education(PE) teachers who completed a study survey.Independent variables included both school-related factors(school-level PA support, availability of and access to PA facilities, and the duration of school PE classes) and community-related factors(the frequency of sports events, sports training opportunities, availability of sports clubs and organizations, and access to PA facilities). The dependent variable was the children's self-reported participation in MVPA. The data were analyzed,in 2017, via multilevel modeling.Results: PA support from school administrators was the only school-level factor significantly related to children's participation in MVPA.Children's perceptions of the frequency of community-sponsored sports events, availability of sports clubs and organizations, and convenient access to PA facilities were associated with a high level of MVPA participation. In regard to residency in urban and rural areas, children attending urban schools who perceived high availability of PA facilities were associated with a low level of participation in MVPA.Conclusion: School support for PA and community PA resources are associated with MVPA among Chinese school children. School PA facilities appear underutilized among urban schools as evidenced by low levels of MVPA among school children.

Catalytic methanation of syngas over Ni-based catalysts with different supports

Co-precipitation method was selected for the preparation of Ni/Al_2O_3, Ni/ZrO_2 and Ni/CeO_2 catalysts, and their performances in methanation were investigated in this study. The structure and surface properties of these catalysts were characterized by BET, XRD, H_2-TPD, TEM and H_2-TPR. The results showed that the catalytic activity at low temperature followed the order: Ni/Al_2O_3>Ni/ZrO_2>Ni/CeO_2. Ni/Al_2O_3 catalyst presented the best catalytic performance with the highest CH_4 selectivity of 94.5%. The characterization results indicated that the dispersion of the active component Ni was the main factor affecting the catalytic activity and the one with higher dispersion gave better performance.

Green Value Chain： A Case Study in Turkey about the Relationships among Antecedents, Initiatives and Results of Green Value Chain Implementations

The present study was conducted to determine the green value chain implementations of large and medium size businesses and to investigate the relationships among antecedents, initiatives and results of green value chain implementations. The antecedents of green value chain implementations were considered from four dimensions namely regulations, public concerns, expected competitive advantage and top management commitment; green value chain initiatives were considered from three dimensions namely green primary activities, green internal support activities and green external support activities; the results of green value chain implementations were considered from two dimensions namely economic performance and socio-ecologic performance. A model was created according to the objectives of the study and hypotheses were formed. Multiple regression analyses were performed to investigate the relationships between the antecedents and initiatives of green value chain implementations. A relationship was not observed between green primary activities and economic and socio-ecologic performance. While a positive relationship was observed between green external support activities and economic performance, a positive relationship was observed between green internal support activities and both economic and socio-ecologic performance.

A New Monodisperse Reactive Resin with Active Groups on the Particle Surface

A novel reactive resin as active support was synthesized by an improved method based on seed swelling and surface coating polymerization. The resin is monosized beads with inner nucleus of cross-linked polymer and surface layer of copolymer containing epoxy groups. The physico-chemical structures of beads were characterized.

Countermeasure Method for Stope Instability in Crown Pillar Area of Cut and Fill Underground Mine

Maintaining stability as well as optimizing recovery of crown pillar, a pillar separating surface area with the uppermost stope in overhand cut and fill underground mining method, is important. Failures in stope may lead to crown pillar failures and cause surface subsidence. Increasing crown pillar thickness will increase crown pillar stability yet reduce mining recovery because part of crown pillar is formed by ore body. Preventing stope failure is the key to maintain stability and optimize recovery of crown pillar. Therefore, it is important to study countermeasure method for stope failure especially in crown pillar area. An attempt has been made to investigate the effectiveness of various countermeasures for stope failure in crown pillar area by means of parametric study. The result shows active type support system is effective for supporting stope in high vertical stress condition while the passive one needs to be installed if the stope is opened in high horizontal stress condition. In general, more supporting capacity from both type support systems is needed if the stope is opened in more severe geological condition. Another countermeasures, sill pillar and surface pile, are introduced for stope instability in crown pillar and non-crown pillar area. Sill pillar is an abandoned slice of unstable stope based on stability analysis. Sill pillar is very effective to stabilize stope both in crown pillar and non-crown pillar area, especially for stope in high horizontal stress condition. Sill pillar application in model with stress ratio 2 can optimize 20 meter thickness of crown pillar into 5 meter. Another proposed countermeasure is surface pile. Surface pile can be installed from the surface to improve stability of crown pillar and stope. The most effective use of surface pile is found in simulation of model with stress ratio 0.75 where surface pile can optimize 15 meter thickness of crown pillar into 5 meter.

THE HYDROXYLATON OF INACTIVE HYDROCARBONS WITH ACTIVE CARBON SUPPORTED METALLOPORPHYRINS

A supported Mn-porphyrin catalyst was prepared by adsorption of Mn-porphyrin on active carbon, and found to be efficient for the hydroxylation of hexane with hydrogen peroxide.

Immobilization of Agaricus Bisporus Laccase on Ceramic-Chitosan Composite Support and Their Properties:Potential for Oily Wastewater Treatment

Laccase was immobilized on the ceramic-chitosan composite support by using glutaraldehyde as the cross-linking reagent. The immobilization conditions and characterization of the immobilized enzyme were investigated. The immobilization of laccase was successfully realized when 3.0 mL of 1.25 mg/mL of laccase at a pH value of 4.0 reacted with 0.15 g of ceramic-chitosan composite support(CCCS) at 4 ℃ for 24 h. The immobilized enzyme exhibited a maximum activity at pH 3.0. The optimal temperatures for immobilized enzyme were 25 ℃ and 50 ℃. The K_m value of immobilized laccase for ABTS was 66.64 μmol/L at a pH value of 3.0 at 25 ℃. Compared with free laccase, the thermal, operating and storage stability of immobilized laccase was improved after the immobilization.

Advances in selective catalytic oxidation of ammonia (NH_(3)-SCO): A review of catalyst structure-activity relationship and design principles

NH_(3) in ambient air directly leads to an increase in the aerosol content in the air. These substances lead to the formation of haze to various environmental problems after atmospheric circulation and diffusion. Controlling NH_(3) emissions caused by ammonia escaping from mobile and industrial sources can effectively reduce the NH_(3) content in ambient air. Among the various NH_(3) removal methods, the selective catalytic oxygen method (NH_(3)-SCO) is committed to oxidizing NH_(3) to environmentally harmless H_(2)O and N_(2);therefore, it is the most valuable and ideal ammonia removal method. In this review, the characteristics of loaded and core-shell catalysts in NH_(3)-SCO have been reviewed in the context of catalyst structure-activity relationships, and the H_(2)O resistance and SO2 resistance of the catalysts are discussed in the context of practical application conditions. Then the effects of the valence state of the active center, oxygen species on the catalyst surface, dispersion of the active center and acidic sites on the catalyst performance are discussed comprehensively. Finally, the shortcomings of the existing catalysts are summarized and the catalyst development is discussed based on the existing studies.

Research on Equipment Support Activity Process Simulation Based on Monte Carlo Method

The influencing factors of the equipment support activity process have the characteristics of nonlinearity, high dimension, many constraints, random uncertainty and fuzzy uncertainty. Monte Carlo method can solve the above problems commendably. This paper analyzes the main equipment support activity process and establishes the sampling plan and simulation model of the medium maintenance process based on Monte Carlo method, and the simulation result verifies a fact that the medium maintenance time can be effectively reduced when parallel operation on some procedures is used. It has a practical value and can give good advice to achieve the capability of equipment supportability.