Thermal instability in a nanofluid layer with a vertical magnetic field

The combined effect of a vertical magnetic field and the boundaries on the onset of convection in an electrically conducting nanofluid layer heated from below is investigated using linear stability theory. The employed model incorporates the effects of Brownian motion and thermophoresis. The boundaries are considered to be either rigid or free. The eigenvalue problem is solved analytically for free–free boundaries and numerically for rigid–rigid and lower-rigid and upper-free boundaries using the Galerkin technique. Numerical results are presented for alumina–water nanofluid.     

Poly(1‐octene) synthesis using high performance supported titanium catalysts

Poly(1‐octene) was synthesized by polymerization of 1‐octene using high performance MgCl₂‐supported TiCl₄ in combination with triethyl aluminum (TEAl) as cocatalyst in n‐hexane for 2 h. Two catalysts, C₁ (diester catalyst) having di‐isobutyl phthalate as internal donor and C₂ (monoester catalyst) having ethyl benzoate as internal donor were utilized for the atmospheric polymerizations to evaluate the influence of structurally different internal donors on the productivity, rate of polymerization and molecular weight profiles. The kinetic profile assessed in terms of variation of reaction parameters like temperature, cocatalyst to catalyst molar ratio and monomer concentration was found to be dependent on them. From these kinetic analyses, optimize conditions for polymerizations of 1‐octene using diester as well as monoester catalyst were elucidated. The difference in the performance of diester and monoester catalyst system can be explained in terms of stability of active titanium species and chain transfer process. NMR spectroscopy of synthesized poly(1‐octene) indicate predominantly isotactic nature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

An enhanced performance through agent-based secure approach for mobile ad hoc networks

This paper proposes an agent-based secure enhanced performance approach (AB-SEP) for mobile ad hoc network. In this approach, agent nodes are selected through optimal node reliability as a factor. This factor is calculated on the basis of node performance features such as degree difference, normalised distance value, energy level, mobility and optimal hello interval of node. After selection of agent nodes, a procedure of malicious behaviour detection is performed using fuzzy-based secure architecture (FBSA). To evaluate the performance of the proposed approach, comparative analysis is done with conventional schemes using performance parameters such as packet delivery ratio, throughput, total packet forwarding, network overhead, end-to-end delay and percentage of malicious detection.     

SOS: Socially omitting selfishness in IoT for smart and connected communities

Smart and connected communities (SCC) is an emerging field of internet of things (IoT), and it has potential applications to improve human life. The improvement may be in terms of preservation, revitalization, livability, and sustainability of a community. The resources of the nodes and devices in the SCC have certain constraints that may not allow the devices and nodes to cooperate to save their resources such as memory, energy, and buffer, or simply maximize their performance. Thus, to stimulate the nodes to avoid selfish behavior, SSC needs a novel and well-organized solution to motivate nodes for cooperation. This article aims to resolve the issue of selfish behaviors in SCC and to encourage the nodes for cooperation. A novel mechanism, socially omitting selfishness (SOS), has been proposed to manage/eradicate selfishness using a socially oriented election process. The election process elects different heads based on weight and cooperation (using Vickrey, Clarke, and Groves model). The election of heads and incentive mechanism encourages the nodes to show participation and behave as highly cooperative members of the community. Furthermore, an extended version of the Dempster Shafer model has been used to discourage the selfish behavior of the participating nodes in the SOS scheme. It uses different monitoring and gateway nodes to efficiently employ the proposed scheme. A mathematical model has been developed for the aforementioned aspects and simulated through NS2 simulation environment to analyze the performance of SOS. The results of the proposed scheme outperform the contemporary schemes in terms of average delivery delay, packet delivery ratio, throughput, and average energy.     

Surface Modification of a Titanium Carbide MXene Memristor to Enhance Memory Window and Low-Power Operation

With the demand for low-power-operating artificial intelligence systems, bio-inspired memristor devices exhibit potential in terms of high-density memory functions and the emulation of the synaptic dynamics of the human brain. The 2D material MXene attracts considerable interest for use in resistive-switching memory and artificial synapse devices owing to its excellent physicochemical properties in memristor devices. However, few memristive and synaptic MXene devices that display increased switching performances are reported, with no significant results. Herein, the conductivity of MXene (Ti₃C₂T_x) is engineered via etching and oxidation to enhance the switching performance of the device. The exceptional properties of partially oxidized MXene memristors include large memory windows and low threshold biases, and the complex spike-timing-dependent plasticity synaptic rules are also emulated. The low threshold potential distribution, reliable retention time (10⁴ s), and distinct resistance states with a high ON–OFF ratio (>10⁴) are the main memory-related features of this device. The experimentally determined switching potentials of the optimized device are also uniformly distributed, according to a statistical probability-based approach. This investigation may promote the essential material properties for use in high-density non-volatile memory storage and artificial synapse systems in the field of innovative nanoelectronic devices.     

Performance evaluation of optical OFDM in direct detected systems based on MZM bias and drive voltages

The impact of DC bias and the RF drive voltage of the dual electrode Mach Zehnder Modulator (DE-MZM) on the transmission performance of optical orthogonal frequency division multiplexing (O-OFDM) direct detected systems is analyzed theoretically and verified by simulation. Selection of optimum bias and drive voltage is necessary to minimize the optical signal to noise ratio (OSNR) requirements and the non-linear distortions in the fiber transmission. In this paper, we compare MZM modulation techniques such as double sideband full carrier and single sideband (SSB) [biased at quadrature and minimum power transmission (MPT) point] with a novel modified SSB OFDM technique. To the best of our knowledge for the first time, a mathematical model for above modified SSB technique is developed to evaluate the OSNR requirement, chromatic dispersion of the fiber, spectral efficiency and the receiver sensitivity against other modulation techniques. Our results show that the modified SSB technique provides high spectral efficiency, receiver sensitivity and low chromatic dispersion against other the modulation techniques, while the one biased at MPT minimizes the OSNR requirements.     

Cybersecurity: Exploring core concepts through six scenarios

The authors introduce and explain core concepts of cybersecurity through six engaging practical scenarios. Presented as case studies, the scenarios illustrate how experts may reason through security challenges managing trust and information in the adversarial cyber world. The concepts revolve around adversarial thinking, including understanding the adversary; defining security goals; identifying targets, vulnerabilities, threats, and risks; and devising defenses. They also include dealing with confidentiality, integrity, availability (known as the “CIA triad”), authentication, key management, physical security, and social engineering. The authors hope that these scenarios will inspire students to explore this vital area more deeply.

The target audience is anyone who is interested in learningabout cybersecurity, including those with little to no background in cybersecurity. This article will also interest those who teach cybersecurity and are seeking examples and structures for explaining its concepts. For students and educators, the authors include selected misconceptions they observed in student responses to scenarios. The contributions are novel educational case studies, not original technical research.

The scenarios comprise responding to an e-mail about lost luggage containing specifications of a new product, delivering packages by drones, explaining a suspicious database input error, designing a corporate network that separates public and private segments, verifying compliance with the Nuclear Test Ban Treaty, and exfiltrating a USB stick from a top-secret government facility.     

Thermal instability in a rotating porous layer saturated by a non-Newtonian nanofluid with thermal conductivity and viscosity variation

The stability of a non-Newtonian nanofluid saturated horizontal rotating porous layer subjected to thermal conductivity and viscosity variation is investigated using linear and nonlinear stability analyses. The model used for the non-Newtonian nanofluid includes the effects of Brownian motion and thermophoresis. The Darcy law for the non-Newtonian nanofluid of the Oldroyd type is used to model the momentum equation. The linear theory based on the normal mode method, and the criteria for both stationary and oscillatory modes are derived analytically. A weak nonlinear analysis based on the minimal representation of truncated Fourier series method containing only two terms is used to compute the concentration and thermal Nusselt numbers. The results obtained during the analysis are presented graphically.     

Removal of Cu(II) and Pb(II) by Pithophora oedogonia: sorption, desorption and repeated use of the biomass

Maximum sorption of Cu(II) and Pb(II) by dried filamentous green alga Pithophora oedogonia occurred at pH 4.5 and 5.0, respectively. Chemical pretreatment could not appreciably enhance the metal sorption ability of the biomass. HCl and EDTA desorbed 92-96% of the sorbed metal from the metal-loaded biomass. Sorption and desorption of both the test metals were very rapid attaining an equilibrium within 15 min. The time course data of both the processes fitted well to the pseudo-first and the pseudo-second-order Lagergren kinetic models with r2> or =0.979. The isotherm equilibrium of Cu(II) and Pb(II) followed the Redlich-Peterson and Sips model very well with r2> or =0.991. The sorption of Cu(II) and Pb(II) at varying biomass doses could be well defined by linear and hyperbolic decrease, respectively. The regenerated biomass of Pithophora has better reusability for Pb(II) than for Cu(II). A good mechanical strength of Pithophora biomass was apparent as only 10-15% loss of biomass occurred at the end of the fifth cycle.     

The Ubiquitin System: An Emerging Therapeutic Target for Lung Cancer

The ubiquitin system, present in all eukaryotes, contributes to regulating multiple types of cellular protein processes such as cell signaling, cell cycle, and receptor trafficking, and it affects the immune response. In most types of cancer, unusual events in ubiquitin-mediated signaling pathway modulation can lead to a variety of clinical outcomes, including tumor formation and metastasis. Similarly, ubiquitination acts as a core component, which contributes to the alteration of cell signaling activity, dictating biosignal turnover and protein fates. As lung cancer acquires the most commonly mutated proteins, changes in the ubiquitination of the proteins contribute to the development of lung cancer. Various inhibitors targeting the ubiquitin system have been developed for clinical applications in lung cancer treatment. In this review, we summarize the current research advances in therapeutics for lung cancer by targeting the ubiquitin system.