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61.
Routing protocols are the binding force in mobile ad hoc network (MANETs) since they facilitate communication beyond the wireless
transmission range of the nodes. However, the infrastructure-less, pervasive, and distributed nature of MANETs renders them
vulnerable to security threats. In this paper, we propose a novel cluster-based trust-aware routing protocol (CBTRP) for MANETs
to protect forwarded packets from intermediary malicious nodes. The proposed protocol organizes the network into one-hop disjoint
clusters then elects the most qualified and trustworthy nodes to play the role of cluster-heads that are responsible for handling
all the routing activities. The proposed CBTRP continuously ensures the trustworthiness of cluster-heads by replacing them
as soon as they become malicious and can dynamically update the packet path to avoid malicious routes. We have implemented
and simulated the proposed protocol then evaluated its performance compared to the clustered based routing protocol (CBRP)
as well as the 2ACK approach. Comparisons and analysis have shown the effectiveness of our proposed scheme. 相似文献
62.
Christian G. Westwood Judy England Michael J. Dunbar Nigel T. H. Holmes David J. Leeming Diana Hammond MCIWEM 《Water and Environment Journal》2017,31(4):528-536
This paper presents a study of 10 English chalk streams in the River Thames Basin historically affected by abstraction of groundwater. Using macroinvertebrates, macrophytes and river discharge records from across 76 monitoring sites, and spanning the period 1992–2009 we assess how the communities change over time. River discharge is seen to be the most influential variable in biological community composition, and is used to calculate the annual average river discharge (in m3/s) needed to sustain different biological assemblages at each study site, from the lowest to the highest expression of fluvial aquatic community development. This represents a bottom‐up or site‐specific approach to the determination of ecological flow thresholds, from which more empirical trends may be inferred at regional level. The approach also provides a useful understanding of the timescales involved in the recovery of communities from drought. 相似文献
63.
Nanoparticulate Delivery of Cancer Cell Membrane Elicits Multiantigenic Antitumor Immunity 下载免费PDF全文
Ashley V. Kroll Ronnie H. Fang Yao Jiang Jiarong Zhou Xiaoli Wei Chun Lai Yu Jie Gao Brian T. Luk Diana Dehaini Weiwei Gao Liangfang Zhang 《Advanced materials (Deerfield Beach, Fla.)》2017,29(47)
Anticancer vaccines train the body's own immune system to recognize and eliminate malignant cells based on differential antigen expression. While conceptually attractive, clinical efficacy is lacking given several key challenges stemming from the similarities between cancerous and healthy tissue. Ideally, an effective vaccine formulation would deliver multiple tumor antigens in a fashion that potently stimulates endogenous immune responses against those antigens. Here, it is reported on the fabrication of a biomimetic, nanoparticulate anticancer vaccine that is capable of delivering autologously derived tumor antigen material together with a highly immunostimulatory adjuvant. The two major components, tumor antigens and adjuvant, are presented concurrently in a fashion that maximizes their ability to promote effective antigen presentation and activation of downstream immune processes. Ultimately, it is demonstrated that the formulation can elicit potent antitumor immune responses in vivo. When combined with additional immunotherapies such as checkpoint blockades, the nanovaccine demonstrates substantial therapeutic effect. Overall, the work represents the rational application of nanotechnology for immunoengineering and can provide a blueprint for the future development of personalized, autologous anticancer vaccines with broad applicability. 相似文献
64.
Sergiu Cecoltan Izabela-Cristina Stancu Diana Maria Drăguşin Andrada Serafim Adriana Lungu Cătălin Ţucureanu Iuliana Caraş Vlad Constantin Tofan Aurora Sălăgeanu Eugeniu Vasile Romain Mallet Daniel Chappard Cristin Coman Mircea Istodorescu Horia Iovu 《Journal of materials science. Materials in medicine》2017,28(10):153
65.
Daniel E. Azofeifa Neville Clark William E. Vargas Hugo Solis E. Avendano Michael Cambronero Diana Valverde-Mendez 《International Journal of Hydrogen Energy》2017,42(35):22373-22378
We report measurements of the optical transmission, between 240 and 1040 nm, and electrical resistivity of polycrystalline zirconium thin films as they absorb hydrogen. Both are measured as H2 pressure is increased up to 880 mbar, at room temperature. Films, 20–22 nm thick, are deposited on fused quartz substrates by e-beam evaporation at 5.3 × 10?7 mbar base pressure and covered with a 8.0 nm Pd over-coat. The morphology of the films is studied by means of AFM images. The complex refractive indices of Zr and Pd are extracted numerically from the transmission spectra by using a spectral projected gradient method for different hydrogen pressures. The corresponding dielectric functions for various Zr hydrogen concentrations are described with the parametric Drude-Lorentz and Brendel-Bormann (DL & BB) models. The Acceptance-Probability-Controlled Simulated Annealing approach is applied to calculate the parameters of the DL & BB model. This allows us to describe the effect of increasing hydrogen absorption on these parameters and in derived quantities, like the relaxation time and the effective mass of conduction electrons, the electrical resistance, the Fermi energy, and the electronic density of states at the Fermi level. 相似文献
66.
The deformation response of random grain boundary networks as a function of temperature and strain rate is explored using molecular dynamics atomistic simulations and an embedded atom method interatomic potential. We find that deformation at higher temperatures promotes both dislocation emission and grain boundary accommodation processes. The results allow estimating the activation energies and volumes for the deformation process. We find activation energy values for the deformation process similar to those for grain boundary diffusion and activation volumes consistent with an atomic shuffling mechanism. Our results suggest a picture of the deformation process as governed by the combination of the applied stress and thermally activated processes. 相似文献
67.
Vladimir A. Basiuk Diana E. Tahuilan-Anguiano Victor Meza-Laguna Taras Yu. Gromovoy Elena V. Basiuk 《Fullerenes, Nanotubes and Carbon Nanostructures》2018,26(8):491-501
We evaluated the reactivity under solvent-free conditions of 2-aminomethyl-15-crown-5 (AM15C5), 2-aminomethyl-18-crown-6 (AM18C6), 1,4,8,12-tetraazacyclopentadecane (TACPD) and rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (tet b) with microcrystalline fullerene C60. The reactions of nucleophilic addition were carried out at temperatures of about 160°C for 5 h in the case of crown ethers and TACPD, and at 180–190°C for 24 h in the case of tet b. Characterization of the products obtained was performed by using Fourier-transform infrared (FTIR) and Raman spectroscopy, laser desorption/ionization time-of-flight (LDI-TOF) mass spectroscopy, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). To provide an additional insight into the reactivity of macrocyclic compounds with C60 molecules, we employed theoretical calculations in the frame of density functional theory (DFT). According to the results of SEM imaging, macrocyclic reagents are generally unable to deeply penetrate into the bulk of fullerene microcrystals (with a possible exception of TACPD). According to TGA measurements, the reaction efficiency is very low for tet b, whereas the average content of organic fraction in C60-AM15C5 and C60-AM18C6 reaches about 29%, and in C60-TACPD, almost 40%. According to LDI-TOF mass spectral analysis, the products of TACPD, tet b and AM15C5 reactions with fullerene have oligomeric or polymeric structure. By using DFT theoretical calculations, the latter observation was explained by enhanced reactivity of secondary amino groups toward nucleophilic addition onto fullerene cage. 相似文献
68.
69.
T. Diana L v. A. de Macedo‐Soares Ph.D. Paulo Jacinto Pastor‐Braga B.Sc. 《Information Technology for Development》2013,19(4):453-485
Abstract This article gives an account of the results of a case study undertaken at a pioneer and particularly prominent firm in the Brazilian computer industry: COBRA — Computadores e Sistemas Brasileiros SA. The study is part of a research project1 whose main goal is the identification of viable organizational and technological options that could enhance the performance of firms in the Brazilian electro‐electronics industry. Among the more important findings, it was observed that the firm has the potential to evolve to a more flexible structure, in keeping with the new requirements of the probable future market scenarios within its sector. Everything indicated, however, that the main constraining factors for bringing about such a structure were connected with the firm's culture and beliefs and with the indirect influence of the National Policy of Information Technology upon these. An hypothesis was put forward for an organizational model, and the necessary supportive computerized technology, which could be particularly appropriate in view of the impending deregulation, of the Brazilian computer industry. Also, in the scope of the current discussion on the restructuring of this industry in terms of a greater concentration, an alternative to the prevailing school of thought was proposed, and for whose success the organizational model at issue purports to be particularly relevant. 相似文献