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Now showing items 1 - 12 of 12

  • Primary Application of the ILS Technology in the Tail Rotor Drive System of the Certain-Type Helicopter

    Duan, Cheng   Gao, Jie   Wang, Yong Hong   Lin, Yong  

    This paper summarizes the connotation, the work objective and the main work content of the ILS (Integrated Logistic Support) technology which belongs to the transmission system by using a template for the development experience of tail rotor drive system of the certain-type helicopter. It introduces a primary way which is about how to improve the work efficiency and reduce the maintenance cost of tail rotor drive system of the certain-type helicopter by using the technology. It expounds the relation between the ILS technology and the reliability, the safety, the maintainability, the supportability and the testability, the ideology of the technology.
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  • Construction of Nitrogen-containing Hierarchical Porous Polymers and Its Application on Carbon Dioxide Capturing

    Duan, Cheng   Du, Zhongjie   Zou, Wei   Li, Hangquan   Zhang, Chen  

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  • Highly Carboxylated, Cellular Structured, and Underwater Superelastic Nanofibrous Aerogels for Efficient Protein Separation

    Fu, Qiuxia   Si, Yang   Duan, Cheng   Yan, Zishuo   Liu, Lifang   Yu, Jianyong   Ding, Bin  

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  • Fabrication of micro-mesopores in macroporous poly (formaldehyde-melamine) monoliths via reaction-induced phase separation in high internal phase emulsion template

    Duan, Cheng   Zou, Wei   Du, Zhongjie   Li, Hangquan   Zhang, Chen  

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  • Fabrication of micro-mesopores in macroporous poly (formaldehyde-melamine) monoliths via reaction-induced phase separation in high internal phase emulsion template

    Duan, Cheng   Zou, Wei   Du, Zhongjie   Li, Hangquan   Zhang, Chen  

    A one-step strategy of preparing hierarchical porous poly (formaldehyde-melamine) monoliths (PFM) with high specific surface area was proposed. Based on the high internal phase emulsion (HIPE) template, the removal of dispersed phase (liquid paraffins) and the reaction-induced phase separation in continuous phase (the solution of parafomaldehyde and melamine) could generate the macropores, mesopores and micropores in PFM simultaneously. As a result, the highest specific surface areas of the prepared PFM could reach 210 m(2)/g, which was obviously higher than that of traditional polyHIPE. The effect of the constitution of the continuous phase of HIPE on the macroporous morphologies, specific surface areas, and micropore volume of PFM were investigated in detail. Moreover, the formation mechanism of micropores and mesopores by reaction-induced phase separation was proposed. Finally, the obtained PFM was applied as CO2 absorbent and the adsorption properties were studied.
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  • Lanthanum histidine with pentaerythritol and zinc stearate as thermal stabilizers for poly(vinyl chloride)

    Li, Mei   Duan, Cheng   Wang, Haiou   Liu, Zhaogang   Wang, Mitang   Hu, Yanhong  

    Lanthanum histidine [La(His)(2) center dot (NO3) center dot 2H(2)O or La(His)(2)] was synthesized via the reaction of histidine and lanthanum nitrate, and it was investigated as a stabilizer for poly(vinyl chloride) (PVC). The results show that La(His)(2) exhibited a stabilizing effect on PVC as a long-term stabilizer because it prolonged the stability time of PVC to 76 min, which was about 24 times longer than the stability time of the pure PVC. The stabilizing effect of La(His)(2) as a costabilizer with pentaerythritol (Pe) and zinc stearate (ZnSt(2)) was also studied. The results show that the use of La(His)(2) with Pe or Pe/ZnSt(2) improved the stability time of PVC. La(His)(2)/Pe/ZnSt(2) provided PVC with a good initial color and long-term stability, and when it was prepared at mass ratios of 0.8: 2.4: 0.8 and 1.6: 1.6: 0.8, the stability times of PVC were improved to 86 and 88 min, respectively. As a nontoxic stabilizer, La(His)(2)/Pe/ZnSt(2) has the potential to replace the toxic stabilizers widely used in PVC manufacturing. (C) 2015 Wiley Periodicals, Inc.
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  • Feeding solution:Crop-livestock integration via crop-forage rotation in the southern Tibetan Plateau

    Duan, Cheng   Zong, Ning   Wang, Jingsheng   Song, Minghua   Zhang, Xianzhou  

    Separated, specialized crop and forage production has a long history on the Tibetan Plateau. Such isolated pattern has led to current concerns of intensified agriculture, environmental degradation and forage shortage in the increasing pressures of population and livestock growth. To tackle the predicament of feed shortage, an alternative to specialized agriculture is crop-forage rotation for potential crop-livestock integration (CLI). However, its feasibility is understudied and the potential remains unanswered in the southern Tibetan Plateau. Based on the analyses of grazing pressure index and growing degree days (GDD), we examined the practicability and modes of crop-forage rotation for feed solution in the middle reaches of the Yarlung Tsangpo Watershed (YTW). Additionally, cultivated land area suitable for forage rotation after crop harvest was defined. Livestock carrying capacity and grazing pressure indices under forage rotation were compared with those only with rangeland and crop residues. We found that the average number of livestock maintained about 9 million standard sheep unit (SU) in the period 2000-2015, which exceeded the carrying capacity provided by rangeland and crop residues. Growing season length are about 200 days ranging from late April to early November, with daily average temperature >=3D 5 degrees C and over 1500 GDD in the Yarlung Tsangpo River valley. About 158,377 ha, accounting for 74.4% of the cultivated land is suitable for annual forage rotation after crop harvest. The appropriate period for annual forage rotation is ca. 80 days, i.e. from 20th August to 8th November after spring crop harvest and from 1st August to 20th October after winter crop harvest. In addition, the information of GDD also provides elevational thresholds for implementing forage rotation practice in the future. The upper limits for forage rotation are 4000 m after spring crop harvest and 4500 m after winter crop harvest. The grazing pressure indices in most counties can be substantially reduced after filling feed gaps through crop-forage rotation. We demonstrate that crop-forage rotation could be a good solution to forage deficits. These findings also provide insights into promising potential for crop-livestock integration to alleviate grazing pressure in the southern Tibetan agricultural area. However, adoption will depend on farmers' preference and market factors. Further efforts are needed to encourage farmers' involvement into the forage rotation by policy guidance.
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  • Carbon nanomaterials induce residue degradation and increase methane production from livestock manure in an anaerobic digestion system

    Hao, Yi   Wang, Yaya   Ma, Chuanxin   White, Jason C.   Zhao, Ziqian   Duan, Cheng   Zhang, Yiluo   Adeel, Muhammad   Rui, Yukui   Li, Guoxue   Xing, Baoshan  

    The present study investigated effects of two carbon-based nanomaterials, multiwall carbon nanotubes and fullerenes, on biogas and methane yield from sheep manure in an anaerobic digestion system over a 45 days period. The results show that the presence of 500 mg/kg multiwall carbon nanotubes or fullerenes increased the daily and accumulative production of methane (by approximately 46.8% and 33.6%), and decreased the total solid content (by approximately 12.8% and 10.4%) and pH. Exposure 50 mg/kg carbon-based nanomaterials had no impact on digestion. A high-throughput sequencing technique was used to analyze the microbial community diversity and composition in the digests across all treatments. The addition of 500 mg/kg fullerenes and multiwall carbon nanotubes notably altered the composition of the bacteria and archaea at the genus level. The change was particularly evident for Methanobacterium, whose relative abundance was significantly increased (by 67%, 53% and 120% upon with 50 mg/kg fullerenes, 50 and 500 mg/kg multiwall carbon nanotubes treatments, respectively), highlighting the positive effects of carbon-based nanomaterials on microorganisms and the subsequent acceleration of methane production. These findings provide important information on the potential use of carbon-based nanomaterials in methane production via altering or tuning the composition of the bacterial and archaeal communities and have relevance for exploring the use of carbon-based nanomaterials in clean energy and agricultural water recycling. (C) 2019 Elsevier Ltd. All rights reserved.
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  • Construction of Nitrogen-Containing Hierarchical Porous Polymers and Its Application on Carbon Dioxide Capturing

    Duan, Cheng   Du, Zhongjie   Zou, Wei   Li, Hangquan   Zhang, Chen  

    The nitrogen-containing hierarchical porous polymers (NHPPs), which possessed micropores, mesopores, and marcopores simultaneously, were constructed by introducing micropores and mesopores into polystyrene foam by post cross-linking of the skeleton via Friedel Crafts reaction. First, polystyrene foams with abundant macropores (voids and windows) were obtained by concentrated emulsion polymerization. Subsequently, micropores and mesopores were generated by post-cross-linking cyanuric chloride into the skeleton of polystyrene foam. Cyanuric chloride was used as external cross-linker because of its rich nitrogen content. Finally, NHPPs with high specific surface areas (up to 1226 m(2)/g) were obtained. The effects of volume fraction of the dispersed phase of concentrated emulsion, DVB in polystyrene matrix, external cross-linker, and solvent on the textural properties of NHPPs were investigated. Then NHPPs were applied as CO2 absorbent, and the maximum CO2 capacity of 141 mg/g at 273 K, 1 bar and the good reproducibility were achieved. Furthermore, the tentative adsorption mechanism of triazine-ring in NHPPs to CO2 was proposed. Most importantly, the relationship between the structures of NHPPs and their CO2 adsorption capacities was analyzed. The results indicated that the CO2 capacities mostly depended on the microporous volume, and the nitrogen content also had impact on the CO2 capacities.
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  • Highly Carboxylated,Cellular Structured,and Underwater Superelastic Nanofibrous Aerogels for Efficient Protein Separation

    Fu, Qiuxia   Si, Yang   Duan, Cheng   Yan, Zishuo   Liu, Lifang   Yu, Jianyong   Ding, Bin  

    Chromatographic media with synchronously large protein adsorption capacity and high processing flux are highly desired in protein separation; however, the creation of such materials still faces enormous challenges. Herein, a robust strategy to develop highly carboxylated monolithic media by combining nanofibrous aerogels' forming technique and an in situ modification approach is reported. The obtained ion-exchange nanofibrous aerogels (IENFAs) exhibit a unique cellular structure consisting of flexible ceramic nanofibers and a functional polymer wrapping layer, endowing them with outstanding underwater superelasticity and compressive fatigue resistance (nearly no plastic deformation after 1000 compressive cycles). Benefiting from the interconnected nanofibrous cellular structure, good hydrophilicity, high carboxylation, and excellent mechanical properties, the IENFAs exhibit synchronously promoted static (2.9 x 10(3) mg g(-1)) and dynamic (1.7 x 10(3) mg g(-1)) lysozyme adsorption capacities and improved buffer flux (2.17 x 10(4) L m(-2) h(-1), gravity driven), which are superior to these reported nanofibrous materials and commercial ion-exchange membranes. The IENFAs also possess outstanding performance stability, easy operation, and excellent regenerability. Moreover, the IENFA-packed column could directly and continuously separate lysozyme from egg white solely driven by gravity, highlighting their excellent practical application performance. This work may provide a new avenue to design and develop next-generation high-performance chromatographic media for bioseparation.
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  • Spatio-temporal distribution pattern of vegetation coverage in Junggar Basin, Xinjiang

    Duan, Cheng   Wu, Ling   He, Lingyun   Wang, Shaoming  

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  • Land Use and Land Cover Change in the Kailash Sacred Landscape of China

    Duan, Cheng   Shi, Peili   Song, Minghua   Zhang, Xianzhou   Zong, Ning   Zhou, Caiping  

    Land use and land cover change (LUCC) is an important driver of ecosystem function and services. Thus, LUCC analysis may lay foundation for landscape planning, conservation and management. It is especially true for alpine landscapes, which are more susceptible to climate changes and human activities. However, the information on LUCC in sacred landscape is limited, which will hinder the landscape conservation and development. We chose Kailash Sacred Landscape in China (KSL-China) to investigate the patterns and dynamics of LUCC and the driving forces using remote sensing data and meteorological data from 1990 to 2008. A supervised classification of land use and land cover was established based on field survey. Rangelands presented marked fluctuations due to climatic warming and its induced drought, for example, dramatic decreases were found in high- and medium-cover rangelands over the period 2000-2008. And recession of most glaciers was also observed in the study period. Instead, an increase of anthropogenic activities accelerated intensive alteration of land use, such as conversion of cropland to built-up land. We found that the change of vegetation cover was positively correlated with growing season precipitation (GSP). In addition, vegetation cover was substantially reduced along the pilgrimage routes particularly within 5 km of the routes. The findings of the study suggest that climatic warming and human disturbance are interacted to cause remarkable LUCC. Tourism development was responsible land use change in urban and pilgrimage routes. This study has important implications for landscape conservation and ecosystem management. The reduction of rangeland cover may decrease the rangeland quality and pose pressure for the carrying capacity of rangelands in the KSL-China. With the increasing risk of climate warming, rangeland conservation is imperative. The future development should shift from livestock-focus animal husbandry to service-based ecotourism in the sacred landscape.
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