Manganese oxide (MnO) is prospective as anode material for lithium-ion batteries (LIBs) due to its low insertion voltage and high reversible capacity. Here, urchin-like MnO microspheres with carbon coating (u-MnO/c) a...
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Manganese oxide (MnO) is prospective as anode material for lithium-ion batteries (LIBs) due to its low insertion voltage and high reversible capacity. Here, urchin-like MnO microspheres with carbon coating (u-MnO/c) are synthesized through hydrothermal method, and its lithium storage performance is investigated. The unique urchin-like structures of u-MnO/c endow it high surface area which provides sufficient contact with electrolyte. The carbon coating can effectively suffer volume change of u-MnO during charge/discharge process. Meanwhile, the carbon coating can effectively improve the conductivity of u-MnO-based anode. Due to the above features, u-MnO/c delivers high initial capacity of 845 mAh g(-1), and an obvious activation process is observed at the beginning of the cycles thanks to the abundant invasion of the electrolyte into u-MnO/c. The large capacity of 723 mAh g(-1) can still be achieved after 80 cycles. This work provides a promising guide for designing high-performance LIBs electrode materials.
The c programming language provides no bounds-checking for arrays. As a result, string operations provided in the standard c library are potentially unsafe. A solution, in the form of a safe string library, is present...
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The c programming language provides no bounds-checking for arrays. As a result, string operations provided in the standard c library are potentially unsafe. A solution, in the form of a safe string library, is presented. The design goals are safety, inter-operability with existing safe and unsafe routines, debugging help and ease of use.
In this work, porous core-shell structured co2Si@Sic/c/SiOc/SiO2/co(3)O(4)nanoparticles were fabricated by a polymer-derived ceramic approach. The in situ formation of mesopores on the shell, microstructural, and phas...
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In this work, porous core-shell structured co2Si@Sic/c/SiOc/SiO2/co(3)O(4)nanoparticles were fabricated by a polymer-derived ceramic approach. The in situ formation of mesopores on the shell, microstructural, and phase evolution of resulting nanoparticles were investigated in detail. The obtained nanoparticles-paraffin composites possess a very low minimum reflection coefficient (Rcmin) -60.9 dB, broad effective absorption bandwidth 3.50 GHz in the X-band and 15.5 GHz in the whole frequency range (from 2.5 to 18 GHz). The results indicate outstanding electromagnetic wave (EMW) absorbing performance among all the reported cobalt-based nanomaterials, due to the reasons as follows: (a) The unique core-shell structure as well as complex phase composition of Sic/c/SiOc/SiO2/co(3)O(4)in the shell, result in a large number of heterogeneous interfaces in the nanoparticles;(b) Nanoparticles have both dielectric and magnetic loss;(c) Mesopores in the shell prolong the propagation path of EMW, thereby increasing the absorption/reflection ratio of EMWs. Thanks to the material structure design, the resulting core-shell structured cobalt-containing ceramic nanoparticles have great potential for thin and high-performance EMW absorbing materials applied in harsh environment.
This paper presents both the design and the pilot formative evaluation study of a computer-based problem-solving environment (named LEcGO: Learning Environment for programming using c using Geometrical Objects) for th...
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This paper presents both the design and the pilot formative evaluation study of a computer-based problem-solving environment (named LEcGO: Learning Environment for programming using c using Geometrical Objects) for the learning of computer programming using c by beginners. In its design, constructivist and social learning theories were taken into account. The general design has taken into consideration models of the learning process and subject matter as well as potential learner behaviour in dealing with fundamental tasks. The main emphasis has been placed on the role of: (a) multiple external representations in student learning, (b) motivation, through performing problem-solving activities taken from the familiar and meaningful context of drawing, using simple geometrical objects, (c) the active participation of students in their own learning by using hands-on experience, (d) appropriate feedback on the actions taken by students, to aid their self-correction, and (e) holistic, activity-based, multi-media, multi-representational and multi-layered content for the learning of basicconcepts of programming using c. LEcGO was pilot evaluated in the field through a qualitative and comparative study where nine 12th grade (18-year-old) students participated. In fact, students faced three similar yet not identical sets of four tasks across three learning environments, namely;paper and pencil (p-p), Turbo c and LEcGO. The data emerging from this field evaluation study indicates that students gain better results within LEcGO than in both the p-p environment and the typical programming environment of Turbo c, while performing similar activities. (c) 2009 Elsevier Ltd. All rights reserved.
As major waste materials in the rice milling industry, rice husks (RHs) have potential industrial applications. In this work, acid solutions were used to extract high-value-added polysaccharide components (hemicellulo...
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As major waste materials in the rice milling industry, rice husks (RHs) have potential industrial applications. In this work, acid solutions were used to extract high-value-added polysaccharide components (hemicellulose and cellulose) from RHs to obtain sugar residues (SRs) for comprehensive utilization. The SRs were converted into c/SiO2 composites after carbonization and ball-milling. The c/SiO2 composites with crystalline cellulose content in the precursor possessed desirable electrochemical properties when tested as an anode material for lithium-ion batteries (LIBs), including cycle performance, initial coulombic efficiency (IcE) and electrical impedance. Meanwhile, a high reversible specificcapacity of 553 mAh g(-1) was maintained after 100 cycles at a current density of 0.1 A g(-1). This method can be used to turn biomass into a potentially valuable anode material with desirable electrochemical properties for LIBs.
Developing high-efficiency and low-cost electrocatalysts for oxygen reduction reaction (ORR) is one of the key objectives for fuel cells. In this work, S-modified co3O4@S-g-c3N4/ccatalyst was prepared by combining py...
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Developing high-efficiency and low-cost electrocatalysts for oxygen reduction reaction (ORR) is one of the key objectives for fuel cells. In this work, S-modified co3O4@S-g-c3N4/ccatalyst was prepared by combining pyrolysis with ultrasonic method. Transmission electron microscopy analysis indicated that the obtained catalyst had a core-shell structure, which used co3O4 as its core and 1.5-nm-thick S-interspersed g-c3N4 encapsulated co3O4 as shell. When the ratio of S to g-c3N4 was 1:3, the as-prepared catalyst co3O4@ S-g-c3N4/c exhibited positive onset potential and higher limiting diffusion current density of 4.00 mA cm(-2) @0.8V, which was 10 and 37% higher than that of co3O4@g-c3N4/c and co3O4/c, respectively. After 2000 cV cycles, the catalyst also showed good durability.
carbon/carbon (c/c)-Siccomposite materials attained much attention due to its unique properties like immense thermal conductivity, high corrosion, and abrasive resistance. Few scholars have systematically studied the...
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carbon/carbon (c/c)-Siccomposite materials attained much attention due to its unique properties like immense thermal conductivity, high corrosion, and abrasive resistance. Few scholars have systematically studied the grinding machinability of 3D c/c-Siccomposite material. In this paper, the grinding experiment of 3D c/c-Siccomposite material was carried out with a resin-bonded diamond grinding wheel. The effect of machining conditions on the grinding force, micromorphology, surface quality, and residual stress was studied, and the material removal mechanism was analyzed in-depth aimed at the three typical fiber orientations. The result shows that the surface roughness of different fiber areas follows the order: 90 degrees fiber > 0 degrees fiber > Normal fiber. The fiber's orientation showed a significant effect on the mechanism of material removal. The residual thermal stress of c/c-Siccomposite material increases from 32.25 to 207.43 MPa during the grinding process. Polishing the ground surface not only can remove the crack layer and residual stress layer but also can introduce residual compressive stress layer, which can effectively enhance the material strength. The 3D c/c-Siccomposite material removal process is distinct from the composite material 2D c/c-Sic and the traditional brittle material. The main removal of c/c-Siccomposite material is recognized as brittle fracture mode. Because of the different mechanical properties of carbon fiber, Sic matrix, and the pyrocarbon interface, the damage of material during grinding is asynchronous. The present work provides a comprehensive understanding for processing 3D c/c-Siccomposite material parts with high quality.
Background: NQO2 protects against radiation-induced myeloproliferative disease, but the mechanism remains unknown. Results: Radiation-induced NQO2, independent of NQO1, competes with the 20 S proteasome for interactio...
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Background: NQO2 protects against radiation-induced myeloproliferative disease, but the mechanism remains unknown. Results: Radiation-induced NQO2, independent of NQO1, competes with the 20 S proteasome for interaction with c/EBP region Ser-268 to Val-279 to stabilize c/EBP, leading to protection against myeloproliferative disease. conclusion: NQO2 stabilizes c/EBP against 20 S degradation to protect against myeloproliferative disease. Significance: Stress-responsive NQO2 functions as an endogenous factor against myeloproliferative diseases. NRH:quinone oxidoreductase 2 (NQO2) is a flavoprotein that protects cells against radiation and chemical-induced oxidative stress. Disruption of the NQO2 gene in mice leads to radiation-induced myeloproliferative diseases. In this report, we showed that the 20 S proteasome and NQO2 both interact with myeloid differentiation factor ccAAT-enhancer-binding protein (c/EBP). The interaction of the 20 S proteasome with c/EBP led to the degradation of c/EBP. NQO2, in the presence of its cofactor NRH, protected c/EBP against 20 S degradation. Deletion and site-directed mutagenesis demonstrated that NQO2 and 20 S competed for the same binding region of S(268)GAGAGKAKKSV(279) in c/EBP. Exposure of mice and HL-60 cells to radiation enhanced the levels of NQO2, which led to an increased NQO2 interaction with c/EBP and decreased 20 S interaction with c/EBP. NQO2 stabilization of c/EBP was independent of NQO1, even though both interacted with the same c/EBP domain. NQO2(-/-) mice, deficient in NQO2, failed to stabilize c/EBP. This contributed to the development of radiation-induced myeloproliferative disease in NQO2(-/-) mice.
Aquatic humic substances from eight confined and unconfined aquifer/aquitard groundwater systems were analyzed for their stable carbon, radiocarbon, deuterium, and elemental contents. Fractionation of groundwater diss...
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Aquatic humic substances from eight confined and unconfined aquifer/aquitard groundwater systems were analyzed for their stable carbon, radiocarbon, deuterium, and elemental contents. Fractionation of groundwater dissolved organiccarbon (DOc) showed that humic substances are an important part of the organic solute load in all groundwaters. Groundwater humates are distinct from other terrestrial humates, and are characterized by low oxygen (36%) and high carbon (53%) contents. Elemental data from water table wells suggests this characteristic oxygen depletion is mainly a result of biochemical processes that occur in the vadose zone. The stable carbon isotopiccomposition of groundwater humates range between −31 and −24%. (PDB) with ann average of −26%., and reflect their terrestrial origins. The deuterium values of groundwater humate vary widely, and are mainly a reflection of 2 H/H variability in the continental water cycle. Radiocarbon analyses suggest a predominant soil zone origin for most groundwater humates, although some groundwater systems are influenced to varying degrees by buried peat or coal. Soluble humate 14 c mean residence times of up to several hundred years in the vadose zone before recharging to groundwater are due to the mixing of young and old organiccarbon sources, rather than advective residence times.
As research and implementation continue to facilitate high-performance computing in Java, applications can benefit from resource management and prediction tools. In this work, we present such a tool for network round-...
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As research and implementation continue to facilitate high-performance computing in Java, applications can benefit from resource management and prediction tools. In this work, we present such a tool for network round-trip time and bandwidth between a user's desktop and any machine running a Web server(not equal). JavaNws is a Java implementation and extension of a powerful subset of the Network Weather Service (NWS), a performance prediction toolkit that dynamically characterizes and forecasts the performance available to an application. However, due to the Java language implementation and functionality (portability, security, etc.), it is unclear whether a Java program is able to measure and predict the network performance experienced by c-applications with the same accuracy as an equivalent c program. We provide a quantitative equivalence study of the Java and c TcP-socket interface and show that the data collected by the JavaNws is as predictable as that collected by the NWS (using c), copyright (c) 2001 John Wiley & Sons, Ltd.
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