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Synthesis, Polytypism, and Dehydration Behaviour of Nitrate-Intercalated Layered Double Hydroxides of Ca and Al
Full text linkRapid precipitation of the hydroxide phase from a mixed metal nitrate solution comprising Ca2+ and Al3+ ions leads to the formation of a one-layered hexagonal polytype of [Ca-Al] layered double hydroxide. In contrast, slow precipitation results in a three-layered polytype of rhombohedral symmetry. Both polytypes comprise a stacking of positively charged metal hydroxide layers having the composition [Ca2Al(OH)6(H2O)2]+. The Ca2+ ions are seven coordinated with water molecules providing the seventh coordination. In the absence of any prior knowledge of the structure of the 1H polytype, translationengleiche and klassengleiche graphs were used to arrive at the space group and atom positions of the 1H polytype. Rietveld refinements of the structures of the two polytypes show that nitrate ions are intercalated in the interlayer gallery with its molecular plane inclined to the metal hydroxide layer. The angle of inclination in the 1H polytype (∼61°) is greater than that in the 3R polytype (∼30°). When the 1H polytype is completely dehydrated, the metal hydroxide layers undergo a rigid translation relative to one another resulting in (i) a 1H → 3R interpolytype transition, and (ii) the grafting of the nitrate ion to the metal hydroxide layer to satisfy the seventh coordination of the Ca2+ ion. The as-prepared 3R polytype has a mixed anion interlayer comprising nitrate and hydroxyl ions. On heating, this phase progressively loses crystallinity before decomposition
Cattaneo-Ltne Effects on the Stability of Brinkman Convection in an Anisotropic Porous Layer
No full textThe stability of Brinkman local thermal nonequilibrium anisotropic porous convection under the impact of Cattaneo law of heat conduction in solid is investigated. In the analysis, anisotropies in permeability and thermal (solid and fluid phases) conductivities are highlighted. Condition for stationary onset and oscillatory onset is obtained by carrying out linear instability analysis. A novel result is that the instability occurs through oscillatory mode against the stationary convection perceived in the absence of Cattaneo effect. The relative magnitudes of governing parameters on the initiation of oscillatory instability are delineated in detail. The thermal and mechanical anisotropies inflict stabilizing and destabilizing effects on the onset, respectively. The influence of mechanical anisotropy, thermal anisotropy of fluid, thermal relaxation time parameters and the Darcy number is to broaden the size of convection cells whereas thermal anisotropy of the solid and the Darcy-Prandtl number demonstrate a mixed behaviour. A first order amplitude equation is derived separately for steady and overstable modes by performing a weak nonlinear stability analysis using a modified multiscale method. Depending on the values of governing parameters, it is seen that the stationary mode bifurcates subcritically and supercritically, while the oscillatory mode always bifurcates supercritically
Synthesis of N?-Protected Amino Sulfenyl Methyl Formamides and Sulfonyl Methyl Formamides: A Simple Protocol
Full text linkChiral amino acid-derived formamides represent one of the most versatile components in multicomponent reactions. Herein, we describe a facile synthesis of Nß-protected amino sulfenyl methyl formamides and sulfonyl methyl formamides via the Mannich reaction of Na-protected amino alkyl thiols followed by oxidation using 3-chloroperbenzoic acid (m-CPBA). This protocol is applicable to a wide range of Fmoc- and Cbz-protected amino acids. Notably, the reaction provides high yield and retains the stereochemistry of the chiral center of the starting componen
An Efficient Routing Algorithm for Optimizing Energy Conservation and Improved Scalability in WSN
Full text linkWireless Sensor Network (WSN) is a familiar technique to develop various real-world applications through sensor nodes on wireless networks. Energy efficiency and scalability are the important challenges in WSN, along withsome other parameters such as reliability, availability, and security. The nodes’ path and communication network have been decided based on routing techniques among the network nodes. Classical routing algorithms have improved the efficiency and accuracy of WSN nodes, but it works only in the limited range. The number of nodes is increased in WSN, and security of data transmitted has a lot of limitations in routing. This problem has been considered for a long time, but the level of improvement is only within a short range, not for larger networks and high-volume nodes. This problem has been overcome by an efficient routing algorithm SEERA (Scalable Energy Efficient Routing Algorithm). Familiar routing protocol techniques such as LEACH (Low Energy Adaptive Clustering Hierarchy), Multi-LEACH, CELL-LEACH when compared with this algorithm shows that SEERA provides better security, energy efficiency and scalability. Also, the proposed algorithm uses hybrid MAC protocols along with the clusters communicated in Intra mode on the network. This research paper summarizes the results of SEERA withmore scalable nodes on WSN and also improved their energy efficiency among all nodes
An Ontology-Based Semantic Approach for First Aid Prediction in Aviation Services Incorporating RBFNN Over a Cloud Server
No full textMid-air medical emergencies can prove to be fatal if appropriate infrastructure is not established in aircrafts. The alarmingly increasing rates of heart attacks around the world pose a huge threat of life endangerment anywhere and anytime. Especially when the passengers are at high altitudes, the airline crew despite being trained may not always be prepared to deal with the worst of unexpected situations. Since such cases need to be dealt in a very prompt and appropriate manner, an arrangement has to be made to receive swift external medical help whenever required. This paper draws attention upon telemedicine in the aviation sector, and how emergencies are handled mid-air. Internet of things plays a major role in virtually connecting the ailing patient with a specialist doctor, who would in turn suggest life-saving measures through remote diagnosis. In order to lessen the diagnosis time and speed up the
SliceNet-AD: slice selection-based convolution neural network model for classification of Alzheimer's disease
No full textIn recent days, a rapid advancement in imaging technologies has tremendously increased the collection of images in the medical field. These emerging technologies have also led the researchers to focus on computer aided diagnosis (CAD) using efficient machine learning and deep learning techniques. In this paper, we have proposed a framework for binary and multiclass classification of Alzheimer's disease (AD) using three-dimensional structural magnetic resonance images (sMRI) and clinical scores from the Alzheimer's Disease Neuroimaging Initiative (ADNI) dataset. The collected images are subjected to pre-processing using FMRIB Software Library. After pre-processing, the three dimensional grey matter tissues are obtained as an output from tissue segmentation comprises of many two dimensional slices. But, processing and training all the slices requires a lot of computational time. Therefore our aim is to
Near-infrared nonlinear optical characteristics of silver nanoparticles embedded borate glasses activated with Sm3+ ions: Effect of heat treatment
No full textThe impact of heat treatment on the nonlinear optical (NLO) features of silver nanoparticle–embedded Sm3+ ion–containing glasses prepared by the melt–quench method has been investigated and discussed in detail. The NLO coefficients were assessed by the Z–scan method in the near-infrared spectral region using femtosecond, MHz laser pulses. The magnitude of different NLO coefficients, such as two–photon absorption (β) and nonlinear refractive index (n2), have been shown to be elevated with the heat treatment. Typically, at 800 nm excitation, the two–photon absorption coefficient increased from 0.816 × 10-11 m/W to 1.282 × 10-11 m/W, and the n2 values increased from 1.896 × 10-19 m2/W to 2.376 × 10-19 m2/W as the heat treatment duration was increased from 10 to 25 h. This improvement in the NLO properties was ascribed to the local field effects stimulated by the silver nanoparticles. The obtained results suggest that the investigated glasses serve as good hosts for fabricating devices such as optical switches and limiters