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Superhydrophobic Vertically Aligned Treelike Carbon Nanostructures
No full textThe lotus leaf shows superhydrophobicity and extreme nonsticking properties due to the two-level roughness features of its surface in addition to the low surface energy. In the thin film of vertically aligned treelike carbon nanostructures, each nanostructure is a multiwalled carbon nanotube aligned vertically to the plane of the substrate with carbon films attached to the nanotubelike branches, giving the overall treelike appearance. These nanostructures also have two-degree roughness due to their unique geometry, which makes the wettability of the material an interesting property to study. The change in hydrophobicity of the material as a function of the deposition time is studied to understand the mutual dependence of the geometry of the nanostructures and the hydrophobicity of the film. The material exhibits superhydrophobicity, showing a static water contact angle as high as 165? for certain deposition conditions with extreme nonsticking properties. © 2019 American Physical Society
Swift combustion synthesis of PbLi 2 Ti 6 O 14 anode for lithium-Ion batteries: Diffusional and electrochemical investigation
No full textLead lithium titanate (PbLi 2 Ti 6 O 14 ) was synthesized by combustion route restricting the annealing at 900°C to just 1 minute. Rietveld analysis confirmed orthorhombic (Cmca) product phase with an average particle size �200 nm and surface area of 2 m 2 /g forming secondary porous particles. From bond valence site energy (BVSE) calculations, 1 D ionic conduction was found along c axis with low activation energy (0.23 eV). AC conductivity analysis revealed a bulk conductivity of 2 � 10 -7 S.cm -1 at room temperature and 1 � 10 -4 S.cm -1 at 200°C with a switch from extrinsic 1D to intrinsic 2D mechanism at 150°C. Li + diffusion coefficient was calculated to be in the order of 10 -12 cm 2 .s -1 . More than 4 lithium (per f.u.) could be reversibly (de)inserted delivering capacity over 160 mAh/g with good cycling retention over 1000 cycles. With a feasible rapid synthesis, good diffusional and electrochemical behavior especially high rate capability, PbLi 2 Ti 6 O 14 can act as a safe 1.35 V anode for rechargeable Li-ion batteries. © The Author(s) 2018. Published by ECS
Handheld, low-cost electronic device for rapid, real-time fluorescence-based detection of Hg 2+ , using aptamer-templated ZnO quantum dots
No full textMercury is one of the most acute toxic heavy metals at trace levels and its detection at parts per billion (ppb) scale in a low-cost, simple way remains challenging. Here, we report a novel �Turn-On� fluorescence sensor based on aptamer-templated ZnO quantum dots (QDs), which was further developed into an electronic detection device and utilized for the rapid detection of mercury ions (Hg 2+ ). Binding of Hg 2+ with the aptamer leads to the formation of a duplex, T-Hg 2+ -T, and this acts as a template for the formation of ZnO QDs. With an increase in the concentration of Hg 2+ , we observed an increase in duplex formation, leading to enhancement in the fluorescence. The limit of detection of the device is 0.1 ppb (0.5 nM), and experimental analysis has a linear range of detection between 0.1 and 10,000 ppb. Electron microscopy studies ascertained the crystalline nature of the aptamer-templated ZnO QDs in the presence of Hg 2+ . Finally, the sensing was implemented as a simple working electronic detection device prototype. A photodiode coupled with an LED source was connected to an Arduino Nanoboard for the development of the device. To the best of our knowledge, this is the first study to report an enhancement in the fluorescence of the aptamer-templated ZnO QDs with an increase in the concentration of Hg 2+ . Moreover, this is the first report of an analyte addition during the synthesis of QDs, leading to fluorescence-based sensing of the added analyte. Thus, a novel fluorescence sensor based on aptamer-templated ZnO QDs has been demonstrated with high sensitivity and selectivity, resulting in a simple electronic detection device
Periprosthetic biomechanical response towards dental implants, with functional gradation, for single/multiple dental loss
No full textThe differences in shape and stiffness of the dental implants with respect to the natural teeth (especially, dental roots) cause a significant alteration of the periprosthetic biomechanical response, which typically leads to bone resorption and ultimately implant loosening. In order to avoid such clinical complications, the implant stiffness needs to be appropriately adapted. In this study, hollow channels were virtually introduced within the designed implant screws for reduction of the overall stiffness of the prototype. In particular, two opposing radial gradients of increasing hollow channel diameters, i.e., outside to inside (Channel 1) and inside to outside (Channel 2) were considered. Two clinical situations of edentulism were addressed in this finite element-based study, and these include a) loss of the first molar, and b) loss of all the three molars. Consequently, two implantation approaches were simulated for multiple teeth loss - individual implantation and implant supported dental bridge. The effects of implant length, approach and channel distribution on the biomechanical response were evaluated in terms of the von Mises stress within the interfacial periprosthetic bone, under normal masticatory loading. The results of our FE analysis clearly reveal significant variation in periprosthetic bone stress between the different implant designs and approaches. An implant screw length of 11 mm with the Channel 2 configuration was found to provide the best biomechanical response. This study also revealed that the implant supported dental bridge approach, which requires lower bone invasion, results in favorable biomechanical response in case of consecutive multiple dental loss. © 2019 Elsevier Lt
Non-Classical Synthons: Supramolecular Recognition by S center dot center dot center dot O Chalcogen Bonding in Molecular Complexes of Riluzole
No full textClassical examples of supramolecular recognition units or synthons are the ones formed by hydrogen bonds. Here, we report the ubiquity of a S ... O chalcogen bonded synthon observed in a series of supramolecular complexes of the amyotrophic lateral sclerosis drug riluzole. Although the potential of higher chalcogens such as Se and Te to form robust and directional chalcogen bonded motifs is known, intermolecular sulfur chalcogen bonding is considered to be weak owing to the lower polarizability of S atoms. Here, the robustness and electronic nature of a S ... O chalcogen bonding non-classical synthon, and the origin of its exceptional directionality have been explored. Bond orders of the drug-coformer chalcogen bonding are found to be as high as one third of a single bond, and they are largely ionic in nature. The contribution of the S ... O chalcogen bonded motifs to the lattice energies of a series of crystals from the Cambridge Structural Database has been analyzed, showing they can be indeed significant, especially in molecules devoid of strong hydrogen bond donor groups
Correlated Electronic Properties of a Graphene Nanoflake: Coronene
No full textWe report studies of the correlated excited states of coronene and substituted coronene within the Pariser-Parr-Pople (PPP) correlated -electron model employing the symmetry-adapted density matrix renormalization group technique. These polynuclear aromatic hydrocarbons can be considered as graphene nanoflakes. We review their electronic structures utilizing a new symmetry adaptation scheme that exploits electron-hole symmetry, spin-inversion symmetry, and end-to-end interchange symmetry. The study of the electronic structures sheds light on the electron correlation effects in these finite-size graphene analogues, which diminishes going from one-dimensional to higher-dimensional systems, yet is significant within these finite graphene derivatives
Local Weak Convergence Based Analysis of a New Graph Model
No full textDifferent random graph models have been proposed as an attempt to model individuals' behavior. Each of these models proposes a unique way to construct a random graph that covers some properties of the real-world networks. In a recent work4], the proposed model tries to capture the self-optimizing behavior of the individuals in which the links are made based on the cost/ benefit of the connection. In this paper, we analyze the asymptotics of this graph model. We prove the model locally weakly converges 1] to a rooted tree associated with a branching process which we named Erlang Weighted Tree( EWT) and analyze the main properties of the EWT
Asymptotically Optimal Uncoordinated Power Control Policies for Energy Harvesting Multiple Access Channels With Decoding Costs
No full textThe objective of this paper is to design a power control policy that maximizes the long-term time-averaged sum throughput of a Gaussian multiple access channel (MAC), where the transmitters as well as the access point (AP) are energy harvesting nodes (EHNs). In addition, the policy is required to facilitate uncoordinated operation of the network. That is, in each slot, the transmitting nodes and the AP need to independently take their actions, e.g., the amount of energy to be used for transmission or whether to turn on and receive the data. First, in order to benchmark the performance of any policy, we derive an upper bound on the throughput achievable, by analyzing a centralized genie-aided system where the nodes have infinite capacity batteries and can freely share the available energy among themselves. In addition, the genie-aided system has non-causal knowledge of the energy arrivals at all the nodes. Next, we show that, surprisingly, a simple time sharing based online policy which requires no coordination among the transmitters and uses time-dilation at the receiver achieves the upper bound asymptotically in the battery size. We also present a policy that requires an occasional one-bit feedback from the AP about its battery state, and show that it requires a smaller sized battery at the receiver compared to a policy which operates without any feedback from the AP, to achieve the same performance. We use Monte Carlo simulations to validate our theoretical results and illustrate the performance of the proposed policies
The formation of alpha at triple junctions of parent beta phase in titanium alloys
No full textWe have examined the formation of alpha phase at grain boundary triple junctions of parent beta in a metastable beta titanium alloy with orientation imaging microscopy based on electron backscattered diffraction (EBSD). As in the case of alpha formed at grain boundaries of parent beta grains, alpha at a triple junction also forms with the Burgers orientation relationship with one of the three neighbouring beta grains. The experimental results are analyzed in terms of the deviation of the 36 possible alpha variants that can form at a triple junction from the Burgers orientation relationship with neighbouring grains
A new ancient lineage of frog (Anura: Nyctibatrachidae: Astrobatrachinae subfam. nov.) endemic to the Western Ghats of Peninsular India
No full textThe Western Ghats (WG) is an escarpment on the west coast of Peninsular India, housing one of the richest assemblages of frogs in the world, with three endemic families. Here, we report the discovery of a new ancient lineage from a high-elevation massif in the Wayanad Plateau of the southern WG. Phylogenetic analysis reveals that the lineage belongs to Natatanura and clusters with Nyctibatrachidae, a family endemic to the WG/Sri Lanka biodiversity hotspot. Based on geographic distribution, unique morphological traits, deep genetic divergence, and phylogenetic position that distinguishes the lineage from the two nyctibatrachid subfamilies Nyctibatrachinae Blommers-Schlosser, 1993 and Lankanectinae Dubois & Ohler, 2001, we erect a new subfamily Astrobatrachinae subfam. nov. (endemic to the WG, Peninsular India), and describe a new genus Astrobatrachus gen. nov. and species, Astrobatrachus kurichiyana sp. nov. The discovery of this species adds to the list of deeply divergent and monotypic or depauperate lineages with narrow geographic ranges in the southern massifs of the WG. The southern regions of the WG have long been considered geographic and climatic refugia, and this new relict lineage underscores their evolutionary significance. The small range of this species exclusively outside protected areas highlights the significance of reserve forest tracts in the WG in housing evolutionary novelty. This reinforces the need for intensive sampling to uncover new lineages and advance our understanding of the historical biogeography of this ancient landmass