70 research outputs found

    Synergic effect within n-type inorganic–p-type organic nano-hybrids in gas sensors

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    This paper describes the exploration of a synergic effect within n-type inorganic–p-type organic nanohybrids in gas sensors. One-dimensional (1D) n-type SnO2–p-type PPy composite nanofibers were prepared by combining the electrospinning and polymerization techniques, and taken as models to explore the synergic effect during the sensing measurement. Outstanding sensing performances, such as large responses and low detection limits (20 ppb for ammonia) were obtained. A plausible mechanism for the synergic effect was established by introducing p–n junction theory to the systems. Moreover, interfacial metal (Ag) nanoparticles were introduced into the n-type SnO2–p-type PPy nano-hybrids to further supplement and verify our theory. The generality of this mechanism was further verified using TiO2–PPy and TiO2–Au–PPy nano-hybrids. We believe that our results can construct a powerful platform to better understand the relationship between the microstructures and their gas sensing performances

    Remote sensing and environmental assessment of wetland ecological degradation in the Small Sanjiang Plain, Northeast China

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    IntroductionThe plain marsh wetland ecosystems are sensitive to changes in the natural environment and the intensity of human activities. The Sanjiang Plain is China’s largest area of concentrated marsh wetland, the Small Sanjiang Plain is the most important component of the Sanjiang Plain. However, with the acceleration of the urbanization and development of large-scale agricultural reclamation activities in the Small Sanjiang Plain in Northeast China, the wetland has been seriously damaged. In light of this degradation this study examines the Small Sanjiang Plain.MethodsFrom the four aspects of area, structure, function, and human activities, we try to construct a wetland degradation comprehensive index (WDCI) in cold region with expert scoring methods and analytic hierarchy process (AHP), coupled with network and administrative unit. The objective was to reveal the degradation of wetlands in Northeast China over three decades at a regional scale.ResultsThe results showed that (1) the overall wetland area decreased between 1990 and 2020 by 39.26×103 hm2. Within this period a significant decrease of 336.56×103 hm2 occurred between 1990 and 200 and a significant increase of 214.62×103 hm2 occurred between 2010 and 2020. (2) In terms of structural changes, the fractal dimension (FRAC) has the same trend as the Landscape Fragmentation Index (LFI) with little change. (3) In terms of functional changes, the average above-ground biomass (AGB) increased from 1029.73 kg/hm2 to 1405.38 kg/hm2 between 1990 and 2020 in the study area. (4) In terms of human activities, the average human disturbance was 0.52, 0.46, 0.57 and 0.53 in 1990, 2000, 2010 and 2020, with the highest in 2010. (5) The composite wetland degradation index shows that the most severe wetland degradation was 49.61% in 2010 occurred between 1990 and 2020. (6) Among the severely deteriorated trajectory types in 2010–2020, mild degradation → serious degradation accounted for the largest area of 240.23×103 hm2, and the significant improvement trajectory type in 1990–2000 accounted for the largest area of 238.50×103 hm2.DiscussionIn brief, we conclude that the degradation of the Small Sanjiang Plain wetland was caused mainly by construction, overgrazing, deforestation, and farmland reclamation. This study can also provide new views for monitoring and managing wetland degradation by remote sensing in cold regions

    Effect of squalene absorption on oxidative stability of highly crosslinked UHMWPE stabilized with natural polyphenols

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    The uptake of synovial lipids into ultra high molecular weight polyethylene (UHMWPE) has been recently related with the in vivo and ex vivo oxidation of irradiated and remelted UHMWPE. Natural polyphenols have been demonstrated effective in protecting highly crosslinked UHMWPE from oxidation. This manuscript aims to investigate how squalene as a model unsaturated lipid affects the oxidative stability of polyphenol-stabilized highly crosslinked UHMWPE. The irradiated UHMWPE showed less squalene uptake and diffusion in comparison to the unirradiated UHMWPE due to the crosslinked structures in the former. Upon accelerated aging at 70 degrees C and 5 atm O-2 for different durations, the presence of squalene significantly accelerated the initiation, development and propagation of oxidation for the virgin and irradiated UHMWPE. The presence of antioxidants including natural polyphenols effectively prosponded and reduced oxidation of the squalene-doped irradiated UHMWPEs. The oxidation levels and depth of irradiated antioxidant/UHMWPE blends were much less than those for the irradiated UHMWPE. It is concluded that the natural polyphenols are effective in prohibiting oxidation related to the presence of squalene. This finding may be of clinical relevance in terms of stabilization of irradiated UHMWPE against synovial lipids-related oxidation. (C) 2014 Elsevier Ltd. All rights reserved

    Technology-enhanced cooperative language learning: A systematic review

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    This systematic review is based on the core database of foreign linguistics and applied linguistics from 2010 to 2022. 54 studies in the field of technology-enhanced cooperative English learning were screened from 3,249 relevant search titles, 11 experimental studies were identified to assess their validity, and the effects of specific variables on effects were explored. The analysis revealed that different forms of technology-enhanced cooperative learning had a significant positive impact on foreign language learners’ performance, with a mean effect size of 0.86. In addition to its impact on language proficiency, technology-enhanced cooperative learning can improve critical thinking skills, communication skills, enhance learners’ language awareness, increase motivation and encourage self-reflection. Some existing problems are worth noting, as students feel a lot of pressure during the collaborative writing process and some students question the reliability of peer feedback. Some researchers also argue that the effectiveness of technology-enhanced cooperative learning is not guaranteed in all cases and that the type of task being collaborated on should be taken into account. In addition, the composition of the team members, their learning styles and the way they interact also have an impact on the effectiveness of cooperation. The review gives implications to the future studies and the implementation of TECLL programs.</p

    Research on the development mode of artificial ecology in Tarim Basin [Chinese language]

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    Abstract in EnglishThe ecological environment in the oases in Tarim Basin becomes more deteriorative since recent 2000 years, especially since recent 100 years due to the over exploitation and utilization of natural resources. In this paper, a comparative analysis between artificial ecology and natural ecology on the aspects of consumption of water resources, effectivity of ecological and environmental protection, management expenses and output benefits is carried out based on the experiences of the oases' construction in Tarim Basin. The results show that the high - benefit artificial ecology is more effective for ecological protection than the low-output natural ecology. Taking the ecological environment in the area on the southern bank of Tarim River in Xayar County as an example, a dynamic input-output analysis is made for the program of forestry construction and land exploitation in the southern part of Tarim Basin, the paper also analyzes the impact of the construction of irrigation works, soil improvement, and implementation of the measures for protecting against wind and fixing sand upon agricultural production. The calculation results show clearly that the artificial ecological construction and land exploitation can be coordinatedly developed. An ecological agriculture with the high quality and high yield will be able to be reached by the way of spiral growth mode with low-input, high-output and re-input so as to achieve a tight connection between the construction of irrigation works, soil improvement, protection against wind and sand fixation, and provide a new way for reforming the traditional agriculture, protecting ecological environment, and realizing a sustainable development

    DISCHARGE CHARACTERISTICS OF Ti AND FILM PREPARATION USING HYBRID HIGH POWER IMPULSE MAGNETRON SPUTTERING

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    Hybrid high power impulse magnetron sputtering (HIPIMS) is a new-generation HIPIMS technique with a pulse and dirrect current power supply parallelled connection operation. In this work, the influence of dirrect current from 0 to 4.0 A supplied by the dirrect current power is investigated on hybrid HIPIMS Ti discharge characteristics, plasma parameters (plasma potential, electron temperature and electron density) and Ti film properties in an Ar atmosphere. The results show that target voltage and current are characterized by a peak with variation of time in different dirrect currents. Although the target voltage is barely affected, the target current decreases with increasing the dirrect current during the pulse turn-on stage. The plasma parameters determined by a Langmuir probe have been significantly influenced by the dirrect current. Moreover, the deposition rate and average roughness increase while the hardness and elastic modulus have a slight decrease with the variation of dirrect current from 1.0 to 3.0 A. The samples are selected for comparison with that prepared by conventional direct current magnetron sputtering (DCMS) at the same average target power 650 and 1500 W. The results demonstrate that Ti films using hybrid HIPIMS have a close deposition rate and a superior quality and performance to those prepared using DCMS especially at the low target power 650 W when the direct current is 1.0 A

    Natural Polyphenols Enhance Stability of Crosslinked UHMWPE for Joint Implants

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    Radiation-crosslinked UHMWPE has been used for joint implants since the 1990s. Postirradiation remelting enhances oxidative stability, but with some loss in strength and toughness. Vitamin E-stabilized crosslinked UHMWPE has shown improved strength and stability as compared with irradiated and remelted UHMWPE. With more active phenolic hydroxyl groups, natural polyphenols are widely used in the food and pharmaceutical industries as potent stabilizers and could be useful for oxidative stability in crosslinked UHMWPE.We asked whether UHMWPE blended with polyphenols would (1) show higher oxidation resistance after radiation crosslinking; (2) preserve the mechanical properties of UHMWPE after accelerated aging; and (3) alter the wear resistance of radiation-crosslinked UHMWPE.The polyphenols, gallic acid and dodecyl gallate, were blended with medical-grade UHMWPE followed by consolidation and electron beam irradiation at 100 kGy. Radiation-crosslinked virgin and vitamin E-blended UHMWPEs were used as reference materials. The UHMWPEs were aged at 120 A degrees C in air with oxidation levels analyzed by infrared spectroscopy. Tensile (n = 5 per group) and impact (n = 3 per group) properties before and after aging as per ASTM F2003 were evaluated. The wear rates were examined by pin-on-disc testing (n = 3 per group). The data were reported as mean +/- A SDs. Statistical analysis was performed by using Student's t-test for a two-tailed distribution with unequal variance for tensile and impact data obtained with n a parts per thousand yen 3. A significant difference is defined with p < 0.05.The oxidation induction time of 100 kGy UHMWPE was prolonged to 144 hours with 0.05 wt% dodecyl gallate and 192 hours with 0.05 wt% gallic acid compared with 48 hours for 0.05 wt% vitamin E-blended UHMWPE. Accelerated aging of these polyphenol-blended UHMWPEs resulted in ultimate tensile strength of 50.4 +/- A 1.4 MPa and impact strength of 53 +/- A 5 kJ/m(2) for 100 kGy-irradiated UHMWPE with 0.05 wt% dodecyl gallate, for example, in comparison to 51.2 +/- A 0.7 MPa (p = 0.75) and 58 +/- A 5 kJ/m(2) (p = 0.29) before aging. The pin-on-disc wear rates of 100 kGy-irradiated UHMWPE with 0.05 wt% dodecyl gallate and 0.05 wt% gallic acid were 2.29 +/- A 0.31 and 1.65 +/- A 0.32 mg/million cycles, comparable to 1.68 +/- A 0.25 and 2.05 +/- A 0.22 mg/million cycles for 100 kGy-irradiated virgin and 0.05 wt% vitamin E-blended UHMWPE.Based on the sample numbers tested in this study, polyphenols appear to effectively enhance the oxidation stability without altering the mechanical properties or pin-on-disc wear rate of radiation-crosslinked UHMWPE.Crosslinked UHMWPE with natural polyphenols with improved oxidative stability and low wear may find clinical application in joint implants

    Self-Organizing Maps Computing on Graphic Process Unit

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    Abstract. Self-Organizing Maps (SOM) is a widely used artificial neural network (ANN) model. Because of its heavy computation load when the map is big and inherent parallel, there is a need to apply a parallel algorithm on it. As a SIMD parallel processor, Graphic processing unit (GPU) shows a fast growing speed than CPU. And it also provides programmability recently. In this paper, the algorithm and result of SOM computing on GPU has been given. The result shows that GPU can make SOM computing much faster than standard CPU. Some design tricks for improving the efficiency of computing has discussed. Based on the results and current trends in the development of GPU, it is reasonable to expect that graphic hardware will widely used in other ANN computing for getting high-performance.

    FlexNFV: Flexible Network Service Chaining with Dynamic Scaling

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