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71.
We report on electrical Raman measurements in transparent and conducting single-wall carbon nanotube (SWNT) thin films. Application of external voltage results in downshifts of the D and G modes and in reduction of their intensity. The intensities of the radial breathing modes increase with external electric field related to the application of the external voltage in metallic SWNTs, while decreasing in semiconducting SWNTs. A model explaining the phenomenon in terms of both direct and indirect (Joule heating) effects of the field is proposed. Our work rules out the elimination of large amounts of metallic SWNTs in thin film transistors using high field pulses. Our results support the existence of Kohn anomalies in the Raman-active optical branches of metallic graphitic materials. 相似文献
72.
Recep Yuksel Begum Yarar Kaplan Emre Bicer Alp Yurum Selmiye Alkan Gursel Husnu Emrah Unalan 《国际能源研究杂志》2018,42(11):3575-3587
A hybrid nanostructure with partially reduced graphene oxide (rGO) and carbon nanofibers (CNFs) was fabricated and used as supercapacitor electrodes. A straightforward, environmentally friendly, and low‐cost microwave‐assisted reduction process was developed for the synthesis of rGO/CNF hybrid structures. The fabricated supercapacitor devices showed a specific capacitance of 95.3 F g?1 and a superior long‐term cycling stability. A capacitance retention of more than 97% after 11 000 galvanostatic charge discharge cycles was obtained. These and other results reported in this paper indicate that high‐rate, all‐carbon, rGO/CNF hybrid nanostructures are highly promising supercapacitor electrode materials. 相似文献
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74.
Neural Computing and Applications - Text summarization resolves the issue of capturing essential information from a large volume of text data. Existing methods either depend on the end-to-end... 相似文献
75.
Emrah Sagir Siamak Alipour Kamal Elkahlout Harun Koku Ufuk Gunduz Inci Eroglu Meral Yucel 《International Journal of Hydrogen Energy》2018,43(32):14987-14995
Biohydrogen production from sugar beet molasses was investigated by using agar immobilized R. capsulatus YO3. A panel photobioreactor (1.4 L) was employed for a long-term hydrogen production in both indoor and outdoor conditions. The impact of several initial molasses concentrations on hydrogen production, yield and productivity were assessed. Indoor studies revealed that initial sucrose concentration in molasses should be kept below 20 mM to prevent inhibition of hydrogen production. The highest hydrogen productivity of 0.64 ± 0.06 mmol H2 L?1 h?1 and yield of 12.2 ± 1.5 mol H2/mol sucrose were obtained in indoors throughout 20 days of operation. For outdoors, hydrogen production continued for 40 days including consecutive 10 rounds under natural outdoor conditions. In outdoor conditions, the maximum hydrogen productivity and yield were 0.79 ± 0.04 mmol H2 L?1 h?1 and 5.2 ± 0.4 mol H2/mol sucrose respectively. These results indicate that the proposed system is promising for biohydrogen production from molasses at large-scale natural conditions. 相似文献
76.
77.
In the present study, a closed-cycle modified atmosphere drying (CC-MAD) system was developed as an alternative drying technique to facilitate drying processes for agricultural commodities appropriate to highly humid and sunny regions with a better quality. An absorption dehumidifying system was designed for working pseudo-continuously with the most efficient absorbent in terms of moisture absorption, desorption rate, and capacity. The system, assisted by a solar panel for absorbent regeneration, was tested, while its optimum working condition was determined by strawberry drying. This unique process was comparatively carried out using hot-air and freeze-drying techniques in terms of processing time and final product quality. Strawberry slices (5?mm thickness) were dried successfully using CC-MAD. The optimum drying conditions of CC-MAD were determined as drying temperature of 60°C, drying air/gas velocity of 3?m/s and drying medium oxygen level of 9.47%. The loss of ascorbic acid was significantly reduced by CC-MAD technique. These losses were found to be 2.9, 6.9, 27.2, and 23.8% by freeze-drying, CC-MAD, hot-air drying, and hot-air drying combined with CC-MAD, respectively. The total monomeric anthocyanins loss was also significantly reduced by the CC-MAD technique (20.3%), in a similar way to that of freeze-drying (18.1%) in comparison with hot-air drying (40.4%). In addition, CC-MAD (12,446?kJ/kg fresh product at 4?h drying time) is three times more advantageous in terms of energy cost compared with freeze-drying (30492.8?kJ/kg fresh product at 24?h drying time) and six times faster in terms of drying time. This new drying system can be used as an alternative to freeze-drying in the drying of foods, especially in products sensitive to oxidation. 相似文献
78.
An experimental study was conducted on the pressure drop characteristics of a variety of vertical packed beds in turbulent flow of air. The materials of different particle diameter, Dp, with a range of sphericity Φ, 0.55 ≤ Φ ≤ 1.00 were used in random loose packing to produce beds of different lengths, L, with a range of porosity, ε, 0.36 ≤ ε ≤ 0.56. In the covered test cases the cross-sectional velocity distribution at the exit plane of the packed beds and the pressure drop ΔPBed were measured in a particle Reynolds number range of Rep, 675 ≤ Rep ≤ 7772. The particular emphasis of the study was given to determine the influence of ε, Φ, Dp, L, Rep on ΔPBed. In this respect the measurements of ΔPBed were compared with the well-known Ergun's Equation and the data were expressed in terms of correlations through introduced dimensionless parameters of pressure coefficient, ΔP? and exit Reynolds number Reexit. The proposed correlations of ΔP? = ΔP?(εRepDp / L) and Reexit = Reexit(RepDp / L) are found to be appropriate for the determination of ΔPBed and mean exit velocity, U, respectively with an acceptable fit of experimental data in an error margin less than ± 20%. The methodology is presented in this paper as an alternative approach to the available literature on packed beds. 相似文献
79.
Rıfat Emrah Özel Ramiz S. J. Alkasir Kayla Ray Kenneth N. Wallace Silvana Andreescu 《Small (Weinheim an der Bergstrasse, Germany)》2013,9(24):4250-4261
Nanoparticle (NP) exposure may induce oxidative stress through generation of reactive oxygen and nitrogen species, which can lead to cellular and tissue damage. The digestive system is one of the initial organs affected by NP exposure. Here, it is demonstrated that exposure to metal oxide NPs induces differential changes in zebrafish intestinal NO concentrations. Intestinal NO concentrations are quantified electrochemically with a carbon fiber microelectrode inserted in the intestine of live embryos. Specificity of the electrochemical signals is demonstrated by NO‐specific pharmacological manipulations and the results are correlated with the 4,5‐diaminofluorescein‐diacetate (DAF‐FM‐DA). NPs are demonstrated to either induce or reduce physiological NO levels depending on their redox reactivity, type and dose. NO level is altered following exposure of zebrafish embryos to CuO and CeO2 NPs at various stages and concentrations. CuO NPs increase NO concentration, suggesting an intestinal oxidative damage. In contrast, low CeO2 NP concentration exposure significantly reduces NO levels, suggesting NO scavenging activity. However, high concentration exposure results in increased NO. Alterations in NO concentration suggest changes in intestinal physiology and oxidative stress, which will ultimately correspond to NPs toxicity. This work also demonstrates the use of electrochemistry to monitor in vivo changes of NO within zebrafish organs. 相似文献
80.
Efficient planning of freight transportation requires a comprehensive look at wide range of factors in the operation and management of any transportation mode to achieve safe, fast, and environmentally suitable movement of goods. In this regard, a combination of transportation modes offers flexible and environmentally friendly alternatives to transport high volumes of goods over long distances. In order to reflect the advantages of each transportation mode, it is the challenge to develop models and algorithms in Transport Management System software packages. This paper discusses the principles of green logistics required in designing such models and algorithms which truly represent multiple modes and their characteristics. Thus, this research provides a unique practical contribution to green logistics literature by advancing our understanding of the multi-objective planning in intermodal freight transportation. Analysis based on a case study from hinterland intermodal transportation in Europe is therefore intended to make contributions to the literature about the potential benefits from combining economic and environmental criteria in transportation planning. An insight derived from the experiments conducted shows that there is no need to greatly compromise on transportation costs in order to achieve a significant reduction in carbon-related emissions. 相似文献