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51.
Hydrogen evolution under visible light over the heterojunction p‐CuO/n‐ZnO prepared by impregnation method
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The semiconducting properties of the heterojunction CuO/ZnO, synthesized by impregnation method from nitrates, are studied for the first time to assess its feasibility for the hydrogen production under visible light, an issue of energy concern. CuO exhibits a direct optical transition at 1.33 eV, due to Cu2+: 3d orbital splitting in octahedral site, and possesses a chemical stability in the pH range (4–14). The Mott–Schottky plot in (Na2SO4, 0.1 M) medium indicates p‐type conduction with a flat band potential of 0.70 VSCE and a holes density of 1.35 × 1017 cm?3. As application, hydrogen evolution upon visible light is demonstrated on the heterojunction ×%CuO/ZnO (x = 5, 10 and 20 wt.%). The best performance occurs at pH ~12 with an evolution rate of 4.8 cm3 min?1 (g catalyst)?1 and a quantum yield of 0.12%. The improved activity is attributed to the potential of the conduction band of CuO (?1.34 VSCE), more negative than that of ZnO, the latter acts as electrons bridge to water molecules. The presence of SO32? reduces the recombination process, thus resulting in more H2 evolution. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
52.
Imen Ben Chaabane Soumaya Hamouda Sami Tabbane 《Wireless Communications and Mobile Computing》2016,16(6):703-716
Multi‐User Coordinated Multi‐Point (MU‐CoMP), which couples CoMP with Multi User‐Multiple Input Multiple Output (MU‐MIMO), appears as a promising solution to enhance the Long Term Evolution‐Advanced (LTE‐A) system performance. However, some challenging issues in MU‐CoMP networks require more investigation. First, the set of users transmitting under CoMP mode should be properly identified. Secondly, time‐frequency resource should be efficiently partitioned between CoMP and non‐CoMP users in order to improve the system radio capacity. Thirdly, a fair and green scheduler is much needed for a more energy efficient system. This paper deals with these three issues. We propose an adaptive transmission mode selection according to the total load in the cluster and to users' quality of service. The adequate size of the Spatial Division Multiple Access users' groups is also analyzed. We finally propose a new scheduling algorithm to further enhance the radio capacity and the energy consumption in the cluster. Simulations results showed that significant improvements are obtained in terms of total system throughput and outage probability in the cluster with our proposed scheme. Moreover, energy efficiency has increased by four times with our proposed scheduling algorithm as compared to commonly used schedulers. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
53.
The properties of short glass fiber reinforced thermoplastic based on polyamide 6 in humid environment are studied. Conditioning was conducted at 90°C. The combined action of water and heat (90°C) affects progressively the mechanical properties. When the injection molded samples were subjected to moisture, decrease in tensile strength and elastic modulus was observed whatever in distilled water or in salt solution. However, there is an enhancement of elongation at break with increasing exposure to humidity. After immersion in water, the fatigue life time is drastically reduced. Scanning electron microscope (SEM) was used in order to examine the fractured samples feature. Results show that water diffuses into the polymer leading to a reduction of the interfacial stress transmissibility. The major contributor of the stiffness loss is the adhesion loss between the fibers and the polymer. POLYM. COMPOS., 35:501–508, 2014. © 2013 Society of Plastics Engineers 相似文献
54.
A detailed theoretical treatment of a one- (1D) and three-dimensional (3D) photothermal deflection (PTD) technique is presented. Important effects of the probe beam size occur in PTD experiments when the radius of this beam is of the order of magnitude of the thermal diffusion length. The calculation of this effect is checked by experiments in paraffin oil at low modulation frequency as well as for 1D and for 3D. In this last case, we have considered two kinds of deflection: normal and transverse, and we have studied their variation for different values of the pump beam radius. The coincidence between theoretical and experimental curves confirms the validity of our theoretical model. 相似文献
55.
Bourdet GL Hassiaoui I McBride R Monjardin JF Baker H Michel N Krakowski M 《Applied optics》2007,46(25):6297-6301
We describe for the first time to our knowledge the performance for a linear array of tapered laser diodes with both fast- and slow-axis collimation using a microlens for fast-axis collimation and a laser-written phase plate for slow-axis collimation and correction of the residual fast-axis errors from lens aberrations, thermal lensing, astigmatism, pointing errors, and other wavefront distortions. The phase plate leads to M(2) factor reductions of 1.5 for the lensed array following the fast axis and 2.6 for the whole bar following the slow axis. 相似文献
56.
Imen Haddad Massimo Mozzon Natale G. Frega 《European Food Research and Technology》2012,235(2):325-332
This study investigates the stereospecific distribution of fatty acids across the triacylglycerol molecules in breast milk obtained at three different periods of lactation. Fatty acids were distributed within the three sn-positions of the glycerol backbone in a highly specific pattern; the shorter fatty acids tend toward the sn-2 and sn-3 positions of the glycerol molecule, whereas the longer chain fatty acids are more in the sn-1 and sn-3 position. Significant differences in fatty acid composition occurred between lactation times, but factors affecting the fatty acids content do not alter their regiospecific fatty acyl profile, although the quantities in each position can be changed. This suggests that the fatty acids regiodistribution profile in human milk related to the optimal infant growth should be used as a standard for the preparation of infant formulas. 相似文献
57.
Olfa Baâtour Hela Mahmoudi Imen Tarchoun Nawel Nasri Najla Trabelsi Rym Kaddour Maha Zaghdoudi Ghaith Hamdawi Riadh. Ksouri Mokhtar Lachaâl Brahim Marzouk 《Journal of the science of food and agriculture》2013,93(1):134-141
BACKGROUND: Two varieties of Origanum majorana (Canadian and Tunisian) were evaluated for their phenolic, flavonoid and tannin contents, individual phenolic compounds and antioxidant activities under NaCl constraint. RESULTS: The results showed a significant variability in phenolic composition and antioxidant behavior between the two varieties under salt stress. The phenolic composition of methanolic extracts was determined by reversed‐phase high‐performance liquid chromatography. Amentoflavone was the predominant flavonoid compound; in addition, trans‐2‐hydrocinnamic acid became the major phenolic acid with salt treatment of the Tunisian variety. In the control, Canadian variety extract was characterized by high levels of gallic acid and amentoflavone. However, under 75 mmol L?1 NaCl, gallic acid content doubled, whereas amentoflavone content was maintained in the Canadian variety. Stimulation of phenolic acid biosynthesis was observed in these two varieties under salt treatment despite the fact that shoots of the Tunisian variety showed higher antioxidant activities compared to those from the Canadian variety. Tunisian O. majorana might have developed tolerance to salinity and avoided tissue damage by activating enzymes involved in the galactosylation of quercetin into quercetin‐3‐galactoside and quercetin‐3‐rhamnoside. CONCLUSION: Our results confirmed the tolerance of Tunisian O. majorana plants. Copyright © 2012 Society of Chemical Industry 相似文献
58.
59.
Magorzata Kus-Likiewicz Patrick Fickers Imen Ben Tahar 《International journal of molecular sciences》2021,22(20)
Recent advances in the synthesis of metal nanoparticles (MeNPs), and more specifically gold nanoparticles (AuNPs), have led to tremendous expansion of their potential applications in different fields, ranging from healthcare research to microelectronics and food packaging. The properties of functionalised MeNPs can be fine-tuned depending on their final application, and subsequently, these properties can strongly modulate their biological effects. In this review, we will firstly focus on the impact of MeNP characteristics (particularly of gold nanoparticles, AuNPs) such as shape, size, and aggregation on their biological activities. Moreover, we will detail different in vitro and in vivo assays to be performed when cytotoxicity and biocompatibility must be assessed. Due to the complex nature of nanomaterials, conflicting studies have led to different views on their safety, and it is clear that the definition of a standard biosafety label for AuNPs is difficult. In fact, AuNPs’ biocompatibility is strongly affected by the nanoparticles’ intrinsic characteristics, biological target, and methodology employed to evaluate their toxicity. In the last part of this review, the current legislation and requirements established by regulatory authorities, defining the main guidelines and standards to characterise new nanomaterials, will also be discussed, as this aspect has not been reviewed recently. It is clear that the lack of well-established safety regulations based on reliable, robust, and universal methodologies has hampered the development of MeNP applications in the healthcare field. Henceforth, the international community must make an effort to adopt specific and standard protocols for characterisation of these products. 相似文献
60.
Gueddi Imen Nasri Othman Benothman Kamal Dague Philippe 《International Journal of Control, Automation and Systems》2017,15(2):776-789
International Journal of Control, Automation and Systems - This paper presents a new interval diagnosis method to detect and isolate actuators faults of an autonomous spacecraft involved in the... 相似文献