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排序方式: 共有216条查询结果,搜索用时 16 毫秒
61.
Huan Ma Wael Mismar Yuli Wang Donald W. Small Mat Ras Nancy L. Allbritton Christopher E. Sims Vasan Venugopalan 《Journal of the Royal Society Interface》2012,9(71):1156-1167
We use time-resolved interferometry, fluorescence assays and computational fluid dynamics (CFD) simulations to examine the viability of confluent adherent cell monolayers to selection via laser microbeam release of photoresist polymer micropallets. We demonstrate the importance of laser microbeam pulse energy and focal volume position relative to the glass–pallet interface in governing the threshold energies for pallet release as well as the pallet release dynamics. Measurements using time-resolved interferometry show that increases in laser pulse energy result in increasing pallet release velocities that can approach 10 m s−1 through aqueous media. CFD simulations reveal that the pallet motion results in cellular exposure to transient hydrodynamic shear stress amplitudes that can exceed 100 kPa on microsecond timescales, and which produces reduced cell viability. Moreover, CFD simulation results show that the maximum shear stress on the pallet surface varies spatially, with the largest shear stresses occurring on the pallet periphery. Cell viability of confluent cell monolayers on the pallet surface confirms that the use of larger pulse energies results in increased rates of necrosis for those cells situated away from the pallet centre, while cells situated at the pallet centre remain viable. Nevertheless, experiments that examine the viability of these cell monolayers following pallet release show that proper choices for laser microbeam pulse energy and focal volume position lead to the routine achievement of cell viability in excess of 90 per cent. These laser microbeam parameters result in maximum pallet release velocities below 6 m s−1 and cellular exposure of transient hydrodynamic shear stresses below 20 kPa. Collectively, these results provide a mechanistic understanding that relates pallet release dynamics and associated transient shear stresses with subsequent cellular viability. This provides a quantitative, mechanistic basis for determining optimal operating conditions for laser microbeam-based pallet release systems for the isolation and selection of adherent cells. 相似文献
62.
Khitouni Nawel Mbarek Wael Ben Guittoum Abderrahim Suñol Joan Josep Khitouni Mohamed Azabou Meriem 《Journal of Superconductivity and Novel Magnetism》2022,35(11):3439-3446
Journal of Superconductivity and Novel Magnetism - A nanostructured nickel–iron alloy having the Ni40Fe60 composition was prepared through the mechanical alloying of the elemental powders in... 相似文献
63.
Masood Ahmad Fasee Ullah Ishtiaq Wahid Atif Khan M. Irfan Uddin Abdullah Alharbi Wael Alosaimi 《计算机、材料和连续体(英文)》2021,67(1):321-336
Internet of Everything (IoE) indicates a fantastic vision of the future, where everything is connected to the internet, providing intelligent services and facilitating decision making. IoE is the collection of static and moving objects able to coordinate and communicate with each other. The moving objects may consist of ground segments and flying segments. The speed of flying segment e.g., Unmanned Ariel Vehicles (UAVs) may high as compared to ground segment objects. The topology changes occur very frequently due to high speed nature of objects in UAV-enabled IoE (Ue-IoE). The routing maintenance overhead may increase when scaling the Ue-IoE (number of objects increases). A single change in topology can force all the objects of the Ue-IoE to update their routing tables. Similarly, the frequent updating in routing table entries will result more energy dissipation and the lifetime of the Ue-IoE may decrease. The objects consume more energy on routing computations. To prevent the frequent updation of routing tables associated with each object, the computation of routes from source to destination may be limited to optimum number of objects in the Ue-IoE. In this article, we propose a routing scheme in which the responsibility of route computation (from neighbor objects to destination) is assigned to some IoE-objects in the Ue-IoE. The route computation objects (RCO) are selected on the basis of certain parameters like remaining energy and mobility. The RCO send the routing information of destination objects to their neighbors once they want to communicate with other objects. The proposed protocol is simulated and the results show that it outperform state-of-the-art protocols in terms of average energy consumption, messages overhead, throughput, delay etc. 相似文献
64.
This paper presents a robust adaptive control strategy for robot manipulators, based on the coupling of the fuzzy logic control with the so‐called sliding mode control (SMC) approach. The motivation for using SMC in robotics mainly relies on its appreciable features. However, the drawbacks of the conventional SMC, such as chattering effect and required a priori knowledge of the bounds of uncertainties can be destructive. In this paper, these problems are suitably circumvented by adopting a reduced rule base single input fuzzy self tuning decoupled fuzzy proportional integral sliding mode control approach. In this new approach a decoupled fuzzy proportional integral control is used and a reduced rule base single input fuzzy self‐tuning controller as a supervisory fuzzy system is added to adaptively tune the output control gain of the decoupled fuzzy proportional integral control. Moreover, it is proved that the fuzzy control surface of the single‐input fuzzy rule base is very close to the input/output relation of a straight line. Therefore, a varying output gain decoupled fuzzy proportional integral sliding mode control approach using an approximate line equation is then proposed. The stability of the system is guaranteed in the sense of the Lyapunov theorem. Simulations using the dynamic model of a 3DOF planar manipulator with uncertainties show the effectiveness of the approach in high speed trajectory tracking problems. The simulation results that are compared with the results of conventional SMC indicate that the control performance of the robot system is satisfactory and the proposed approach can achieve favorable tracking performance, and it is robust with regard to uncertainties and disturbances. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
65.
Shirin Hafezi Maha Saber-Ayad Wael M. Abdel-Rahman 《International journal of molecular sciences》2021,22(19)
The most frequent mutated oncogene family in the history of human cancer is the RAS gene family, including NRAS, HRAS, and, most importantly, KRAS. A hallmark of pancreatic cancer, recalcitrant cancer with a very low survival rate, is the prevalence of oncogenic mutations in the KRAS gene. Due to this fact, studying the function of KRAS and the impact of its mutations on the tumor microenvironment (TME) is a priority for understanding pancreatic cancer progression and designing novel therapeutic strategies for the treatment of the dismal disease. Despite some recent enlightening studies, there is still a wide gap in our knowledge regarding the impact of KRAS mutations on different components of the pancreatic TME. In this review, we will present an updated summary of mutant KRAS role in the initiation, progression, and modulation of the TME of pancreatic ductal adenocarcinoma (PDAC). This review will highlight the intriguing link between diabetes mellitus and PDAC, as well as vitamin D as an adjuvant effective therapy via TME modulation of PDAC. We will also discuss different ongoing clinical trials that use KRAS oncogene signaling network as therapeutic targets. 相似文献
66.
Ayman S. Al-Hussaini Wael E. El-Bana Nasser A. El-Ghamaz 《Polymer-Plastics Technology and Engineering》2020,59(6):630-641
ABSTRACTThe present work describes a remarkable synthetic interest of semiconducting core-shell nanocomposites (CSNCs) contained aluminum oxide. Al2O3@terpoly(aniline, anthranilic acid, and o-phenylenediamine) (Al2O3/PANI-AA-o-PDA) CSNCs were fabricated by the fivefold molar ratio of the appropriate moieties with various quantities of γ-Al2O3 by oxidative polymerization. The formation of the Al2O3/PANI-AA-o-PDA CSNCs was confirmed by spectral characteristics. The feature of CSNCs is core-shell nano-rods structure with sizes 19–39 nm. The recorded σdc is 8.8 × 10?9-4.8 × 10?8 Ω?1 m?1 being in the range of semiconductor materials at room temperature and increases with increasing temperature. The newly fabricated materials were investigated as antimicrobial agents. The setup presents a facile, cheap, novel and beneficial methodology to develop novel CSNCs acquiring the required numerous functionality. 相似文献
67.
Multibody System Dynamics - This paper addresses the task-space robust trajectory tracking control problem for robot manipulators in the presence of uncertainties and external disturbances. First,... 相似文献
68.
69.
Wael G. Alheadary Ki‐Hong Park Mohamad‐Slim Alouini 《Wireless Communications and Mobile Computing》2016,16(16):2730-2742
In this paper, we derive the performances of optical wireless communication system utilizing adaptive subcarrier intensity modulation over the Malaga turbulent channel. More specifically, analytical closed‐form solutions and asymptotic results are derived for average bit error rate, achievable spectral efficiency, outage probability, and ergodic capacity by utilizing series expansion identity of modified Bessel function. Our asymptotic and analytical results based on series solutions with finite numbers highly matched to the numerical results. By exploiting the inherent nature of fading channel, the proposed adaptive scheme enhances the spectral efficiency without additional transmit power while satisfying the required bit error rate criterion. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
70.
Tayel AA Salem MF El-Tras WF Brimer L 《Journal of the science of food and agriculture》2011,91(12):2160-2165
BACKGROUND: Feed contamination with mycotoxins is a major risk factor for animals and humans as several toxins can exist as residues in meat and milk products, giving rise to carry‐over to consumers via ingestion of foods of animal origin. The starting point for prevention, in this chain, is to eliminate the growth of mycotoxigenic fungi in the animal forage. Ten plant extracts, recommended in Islamic medicine, were evaluated as antifungal agents against mycotoxigenic Aspergilli, i.e. Aspergillus flavus and A. ochraceus, growth in organic maize silage. RESULTS: Most extracts had remarkable antifungal activities using both qualitative and quantitative evaluation methods. Cress (Lepidium sativum) seed extract was proven to be the most powerful among the plants examined. Blending of the most effective extracts (garden cress seed, pomegranate peel and olive leaf extracts), individually at their minimal fungicidal concentrations, with maize silage resulted in the reduction of inoculated A. flavus colony counts by 99.9, 99.6 and 98.7%, respectively, whereas silage blending with the combined extracts completely prohibited fungal growth for up to 30 days of incubation under aerobic conditions. CONCLUSION: Besides the health promoting effects, silage blending with the bioactive plant extracts examined could lead to the required protection from pathogenic and mycotoxigenic fungi. Copyright © 2011 Society of Chemical Industry 相似文献