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51.
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
52.
Effects of Stitching on Delamination of Satin Weave Carbon-Epoxy Laminates Under Mode I,Mode II and Mixed-Mode I/II Loadings 总被引:1,自引:0,他引:1
The objective of the present study is to characterize the effect of modified chain stitching on the delamination growth under
mixed-mode I/II loading conditions. Delamination toughness under mode I is experimentally determined, for unstitched and stitched
laminates, by using untabbed and tabbed double cantilever beam (TDCB) tests. The effect of the reinforcing tabs on mode I
toughness is investigated. Stitching improves the energy release rate (ERR) up to 4 times in mode I. Mode II delamination
toughness is evaluated in end-notched flexure (ENF) tests. Different geometries of stitched specimens are tested. Crack propagation
occurs without any failure of stitching yarns. The final crack length attains the mid-span or it stops before and the specimen
breaks in bending. The ERR is initially low and gradually increases with crack length to very high values. The mixed-mode
delamination behaviour is investigated using a mixed-mode bending (MMB) test. For unstitched specimens, a simple mixed-mode
criterion is identified. For stitched specimens, stitching yarns do not break during 25% of mode I ratio tests and the ERR
increase is relatively small compared to unstitched values. For 70% and 50% of mode I ratios, failures of yarns are observed
during crack propagation and tests are able to capture correctly the effect of the stitching: it clearly improves the ERR
for these two mixed modes, as much as threefold. 相似文献
53.
In the last few years, the development of wireless local area networks (WLANs) has become a major goal in the field of computer and wireless communications. The Network Technologies Research group at the Communications Research Center in Canada has been working on a project to develop a high speed outdoor WLAN. In contrast to many existing WLANs, the new WLAN supports multimedia traffic such as voice, data and video; and will be used mainly in an outdoor environment with a cell coverage range of approximately 20 km. In this paper the physical layer design alternatives for the outdoor WLAN with a speed of 10 to 20 Mbps are described. Simulation results for some of the techniques considered to be used for the WLAN system are presented. The study is concluded by proposing two possible systems that one may consider for the implementation of a high speed outdoor WLAN. Although this study was primarily focused on WLAN applications, the results presented in this paper are applicable to several high speed wireless networks. 相似文献
54.
A. Smida R. Ghayoula N. Nemri H. Trabelsi A. Gharsallah D. Grenier 《International Journal of Communication Systems》2014,27(12):4449-4466
Phased antenna array design is one of the most important electromagnetic optimization problems. This research combined the Taguchi method and artificial intelligence methods, used them as the prediction tool in designing parameters for the communication system, and then constructed a set of the optimal parameter analysis flow and steps. In this paper, we present an application of artificial neural networks in the electromagnetic domain. We particularly look at the multilayer perceptron network, which has been the most used of artificial neural networks architectures both in the electromagnetic domain and in the Taguchi optimization technique and describes the Taguchi method to optimize the excitations elements of the linear array to produce a radiation pattern with minimum side lobe level and null placement control. This paper investigates how the implementation of the signal processing in hardware affects the performance of the adaptive array antenna. The investigation is confined to uplink or receive antenna array only. Results of a prototype of antenna array with feeding values designed using the proposed techniques are also presented. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
55.
56.
A Greffard N Trabelsi H Terzidis J Bignon MC Jaurand Y Pilatte 《Canadian Metallurgical Quarterly》1997,1334(2-3):140-148
Sulfated glycosaminoglycans are known to inhibit mammalian acid-active sialidase. Although the inhibition depends clearly on the presence of sulfate groups on these macromolecules, there was no information on the intrinsic inhibitory potency of inorganic sulfate. In this study, we demonstrate that inorganic sulfates inhibit acid-active Mu-Neu5Ac sialidase of U937 cells. This inhibition was found to be reversible and it appeared to be of the mixed competitive type. Sulfate-induced inhibition was also observed in other cells as well as with other substrates such as sialyl lactose and bovine mixed brain gangliosides. We conclude that the intrinsic inhibitory potency of sulfate groups may be significantly involved in the inhibition of acid-active sialidase by sulfated glycosaminoglycans. In addition, inorganic sulfate by its apparent potency to selectively inhibit acid sialidases might constitute an interesting tool for the characterisation of the minor forms of sialidases occurring in mammalian cells. 相似文献
57.
H. Trabelsi E. Kannatey-Asibu Jr. 《The International Journal of Advanced Manufacturing Technology》1991,6(3):220-231
Pattern-recognition analysis of sound radiation was developed as a basis for monitoring the metal-cutting process. The sound-pressure
signals radiated during cutting under fixed conditions were recorded using a sharp tool, a worn tool and a broken tool. A
round bar of heat-treated AISI 4340 steel was machined in cylindrical turning, using a titanium-carbide-coated cutting tool.
The spectral components in the 0–10 kHz range were used as features. Using resubstitution, signals coming from sharp and worn
tools were easily distinguished, resulting in a 100% classification with just two features, being the average of the low (0–5
kHz) and high (5–10 kHz) frequency ranges. With tool breakage, two acceptable classifications were obtained using independent
testing, the first with a performance of 100%, 75% and 100% for sharp, worn and breakage signals respectively, using nine
features, and the second with 80%, 88% and 80%, using eight features. 相似文献
58.
Wireless Networks - Using efficiently the wireless sensor networks based on IEEE 802.15.4/zigbee remains a real challenge for the forest fire detection and monitoring applications. The most... 相似文献
59.
60.
Trabelsi Youssef Ali Naim Ben Alsaif Haitham Kahouli Omar Kanzari Mounir 《Journal of Superconductivity and Novel Magnetism》2022,35(9):2311-2317
Journal of Superconductivity and Novel Magnetism - In this numerical simulation, we study a new optical device based on semiconductor-superconductor structures, showing narrower broadband... 相似文献