排序方式: 共有44条查询结果,搜索用时 15 毫秒
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Christophe Rehmet Frederic Fabry Vandad Rohani François Cauneau Laurent Fulcheri 《Plasma Chemistry and Plasma Processing》2013,33(4):779-796
A 3-phase AC plasma torch has been developed and aims at overcoming some limits of the classical DC torches in terms of efficiency, cost and reliability. However, the arc behavior in 3-phase plasma torch remains poorly explored. This paper is dedicated to the high speed video camera at 100,000 frames per second and electrical signal analyses of arcs behavior in a 3-phase AC arc plasma torch. First, a reference case at 150 A, in nitrogen as working gas, has been deeply analyzed. Afterwards, a parametric study based on current and inter-electrode gap has been carried out. Results show that only one arc can exist at a given time and arcs rotate by switching from a pair of electrodes to another one, following the maximal electrical gap potential. However, a particular “abnormal” arc behavior was sometimes observed. Indeed, the arc motion within the inter-electrode gap increases the heat exchange and stabilizes the 3-phase discharge whereas the system is unbalanced when the arc is in the periphery. The analysis highlights that the arc motion is strongly influenced by the electrode jet velocity and repulsive Lorentz forces. The parametric study shows that the current increases both jet velocity and arc discharge stability. Elsewhere, the increase of the inter-electrode gap can also stabilizes the electrical 3-phase arc discharge. Furthermore, the correlation between arc motion and current waveform is highlighted. This work is likely to open the way toward a better understanding of 3-phase discharges in the perspective of their further optimization. 相似文献
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This study presents the removal of Cd(II) from aqueous solution by the sorption process in the presence (sono-sorption) and absence (conventional method) of ultrasound. Batch experiments were conducted to study the main parameters such as sorbate concentration, amount of sorbent, contact time, and ultrasound intensity. In addition, the sorbate/sorbent concentration ratios were studied in two different ways: (a) in a constant sorbate concentration and variable amount of sorbent, (b) in a constant amount of sorbent and variable sorbate concentration. The results indicated that under proper conditions, there was a possibility to remove cadmium ion very fast and efficiently from aqueous solution. In addition, the intensity of ultrasound and the sorbate/sorbent concentration ratio were two important factors for the removal of this pollutant and therefore, this study was focused mostly on these two variables. 相似文献
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Elaheh Rohani Rad Henri Vahabi Krzysztof Formela Mohammad Reza Saeb Sabu Thomas 《先进技术聚合物》2019,30(9):2250-2260
Although significant progress has been made in the design and application of injectable hydrogels for biomedical applications, concurrent control of rheological and mechanical properties of injectable hydrogels has remained as an open challenge to the researchers. In this work, we introduce and put into practice a photo‐curable poloxamer (also known as Pluronic)/graphene oxide (Plu/GO) injectable hydrogel with well‐controlled rheological and mechanical properties. Acrylate group was anchored to hydrogel structure to endow photo‐crosslinking ability through decelerating degradation rate of poloxamer hydrogels after injection. It was found that the modified Plu remains stable in biological media for a long‐term period without significant weight loss. Rheological properties of hydrogels were also carried out as essential prerequisite for an ideal injectability via frequency sweep, flow curve, recovery, and yield stress before and after modification, signifying shear‐thinning behavior of Plu/GO hydrogels with high recoverability. The viscosity of shear‐thinning‐like hydrogels dropped at higher shear stress, which facilitated injection process. Moreover, mechanical behavior of Plu was optimized by manipulating the content of Plu, degree of modification with reactive precursor, curing, and particularly incorporation of GO without deteriorating effects on rheological behavior of Plu. 相似文献
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Er3+-doped tellurite glasses of the (80 ? x)TeO2–20ZnO–(x)Er2O3 system (0.5 mol% ? x ? 2.5 mol%) have successfully been made by melt-quenching technique and their structure has been investigated by means of DTA and Raman spectroscopy. The DTA results show the thermal parameters; such as the glass transition temperature (Tg) and crystallization temperature (Tc) were determined. It is found that this system provides a stable and wide glass formation range in which the glass stability around 99–140 °C may be obtained. The Raman spectroscopy used the structural studies in the glass system. Two Raman shift peaks were observed around 640–670 cm?1 and 720–740 cm?1, which correspond to the stretching vibration mode of TeO4 tbp and TeO3 tp, respectively. It is found that the spectral shift in Raman spectra is depending on the Er2O3 content. This evolution is an indication of the changes in the basic unit of the glass structure. 相似文献
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Phosphate glasses doped with samarium oxide have been made using the melt quenching technique. The density of the glass was
determined using the Archimedes method while the Vickers hardness was measured using a micro-vicker tester. Both density and
hardness have shown an increasing trend with the addition of a small amount of Sm2O3. The refractive index was characterized using UV-visible spectroscopy and the Sellmeier fitting equation was used to verify
the result. The refractive index was found to vary from 1.972 to 1.807 depending on the wavelength and well agreed with the
fitting curve 相似文献
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Mahmoud Mirmehrabi Sohrab Rohani Michael C. Jennings 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(12):o695-o698
The crystal structure of the title compound (systematic name: 2′,3′‐didehydro‐2′,3′‐deoxythymidine), C10H12N2O4, consists of two molecules in the asymmetric unit bound together by hydrogen bonds. The conformational geometry differentiates this form of stavudine from its two previously published polymorphs. In addition, a different hydrogen‐bonding scheme is observed compared with the previous two structures. This polymorph is the thermodynamically most stable form of the antiviral drug, as evidenced by differential scanning calorimetry (DSC) and IR data. 相似文献
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Using flexible heat flux sensors mounted on the lateral and bottom of outside reactor wall, a new approach is developed for
isothermal calorimetric technique to overcome the disadvantages of heat flow calorimetric methods. Although the proposed system
needs a calibration procedure before or after the reaction completion to evaluate the lateral heat transfer area, the measurement
is versatile and totally independent of the reaction media, jacket fluid, and the variations of heat transfer coefficient.
Knowledge of the variations of the heat transfer coefficient is essential for the effective control and scale up of a reactor
and can be inferred by the new method during the reaction. The stirrer power and the heat loss can be determined easily as
well. No pre-calibration is needed for the sensors and no heating element is applied inside the reactor for temperature control.
Experiments are carried out to validate the performance of the new proposed technique. With the help of a heater, the heat
generated in the reactor is measured at various levels of power input. The predicted heater power inputs are in good agreement
with the corresponding heat inputs. The relative detection limit in the range of 0.8–1 W L−1 is expected for this technique. Using the hydrolysis of acetic anhydride, the heat of reaction at 25°C is determined, which
is within the range reported in the literatures. The capability of the system to deal with the variations in the overall heat
transfer coefficient is also demonstrated using a simulated reaction. 相似文献