Ion implantation doping of OMCVD grown GaN

Doping by ion implantation using Si, O, Mg, and Ca has been studied in single crystal semi-insulating and n-type GaN grown on a-sapphire substrates. The n-and p-type dopants used in this study are Si and O; Mg and Ca, respectively. Room temperature activation of Si and O donors has been achieved after 1150°C annealing for 120 s. The activation of Mg and Ca acceptors is too low to measure at both room temperature and 300°C. Using higher doses to achieve a measurable p-type conduction increases the amount of damage created by the implantation. Rutherford back scattering measurements on this material indicate that the damage is still present even after the maximum possible heat treatment. Secondary ion mass spectrometry measurements have indicated a redistribution in the measured profiles of Mg due to annealing.     

Thermally stimulated discharge current studies in pure and fe-doped polystyrene films

Studies were made on the thermally stimulated discharge currents (TSDCs) in pure (undoped) and Fe-doped polystyrene films as a function of polarizing field, polarizing temperature and dopant concentration. While undoped films exhibited a single peak, doped films showed two peaks one at low temperatures and another at high temperatures. The low temperature peak, which exhibits a shift towards lower temperatures with increasing dopant concentration, is attributed to the relaxation of the main chain, while the high temperature peak, which shows a tendency to shift towards higher temperatures with dopant concentration, is due to space charge polarization. The TSDCs were higher for low dopant concentrations than their undoped counterparts, while for high concentrations of the dopant, the TSDCs decreased. Formation of charge transfer complexes at low dopant concentrations and molecular aggregates at higher dopant concentrations are suggested as the possible reasons for this behaviour.     

Curcumin Prevents Cerebellar Hypoplasia and Restores the Behavior in Hyperbilirubinemic Gunn Rat by a Pleiotropic Effect on the Molecular Effectors of Brain Damage

Bilirubin toxicity to the central nervous system (CNS) is responsible for severe and permanent neurologic damage, resulting in hearing loss, cognitive, and movement impairment. Timely and effective management of severe neonatal hyperbilirubinemia by phototherapy or exchange transfusion is crucial for avoiding permanent neurological consequences, but these therapies are not always possible, particularly in low-income countries. To explore alternative options, we investigated a pharmaceutical approach focused on protecting the CNS from pigment toxicity, independently from serum bilirubin level. To this goal, we tested the ability of curcumin, a nutraceutical already used with relevant results in animal models as well as in clinics in other diseases, in the Gunn rat, the spontaneous model of neonatal hyperbilirubinemia. Curcumin treatment fully abolished the landmark cerebellar hypoplasia of Gunn rat, restoring the histological features, and reverting the behavioral abnormalities present in the hyperbilirubinemic rat. The protection was mediated by a multi-target action on the main bilirubin-induced pathological mechanism ongoing CNS damage (inflammation, redox imbalance, and glutamate neurotoxicity). If confirmed by independent studies, the result suggests the potential of curcumin as an alternative/complementary approach to bilirubin-induced brain damage in the clinical scenario.     

Combining the evidences of temporal and spectral enhancement techniques for improving the performance of Indian language identification system in the presence of background noise

Language Identification has gained significant importance in recent years, both in research and commercial market place, demanding an improvement in the ability of machines to distinguish between languages. Although methods like Gaussian mixture models, hidden Markov models and neural networks are used for identifying languages the problem of language identification in noisy environments could not be addressed so far. This paper addresses the performance of automatic language identification system in noisy environments. A comparative performance analysis of speech enhancement techniques like minimum mean squared estimation, spectral subtraction and temporal processing, with different types of noise at different SNRs, is presented here. Though these individual enhancement techniques may not yield good performance with different types of noise at different SNRs, it is proposed to combine the evidences of all these techniques to improve the overall performance of the system significantly. The language identification studies are performed using IITKGP-MLILSC (IIT Kharagpur-Multilingual Indian Language Speech Corpus) databases which consists of 27 languages.     

A Hybrid RF and Vision Aware Fusion Scheme for Multi-Sensor Wireless Capsule Endoscopic Localization

A huge torrent of data traffic is generated from various heterogeneous applications and services at the Internet backbone. In general, at the backbone, all such applications and services are allocated spectral resources under a shared spectrum environment within elastic optical networks (EONs). In such a fully shared environment, connection requests (CRs) belonging to different traffic profiles compete for spectral resources. Hence, it is very challenging for network operators to resolve resource conflict that occur at the time of provisioning resources to such CRs. The heterogeneous traffic profile (HTP) considered in this work includes permanent lightpath demands (PLDs) and scheduled lightpath demands (SLDs). We propose various distance adaptive routing and spectrum assignment (DA-RSA) heuristics to resolve resource conflict among these two traffic profiles in EONs under a full sharing environment. Conventionally, preemption was the only technique to resolve such resource conflict among HTPs. Since preemption involves the overhead of selecting CRs to be preempted and then deallocating the resources given to those CRs, excessive preemption adversely affects the performance of the network. Therefore, in this work, we utilized bandwidth splitting as a solution to resolve resource conflict among HTPs under such a shared environment in EONs. Moreover, an integrated solution consisting of splitting and preemption is also proposed. We refer to this new integration as flow-based preemption. Our simulation results demonstrate that bandwidth splitting-based heuristics yield significant improvement in terms of the amount of bandwidth accepted in the network, link and node utilization ratio, number of transponders utilized and the amount of bandwidth dropped due to preemption. Moreover, the flow-based preemption approach is proved to be superior in performance amongst all proposed strategies.

     

Emergence of Gold‐Mesoporous Silica Hybrid Nanotheranostics: Dox‐Encoded,Folate Targeted Chemotherapy with Modulation of SERS Fingerprinting for Apoptosis Toward Tumor Eradication

Strategically fabricated theranostic nanocarrier delivery system is an unmet need in personalized medicine. Herein, this study reports a versatile folate receptor (FR) targeted nanoenvelope delivery system (TNEDS) fabricated with gold core silica shell followed by chitosan–folic acid conjugate surface functionalization by for precise loading of doxorubicin (Dox), resembled as Au@SiO₂‐Dox‐CS‐FA. TNEDS possesses up to 90% Dox loading efficiency and internalized through endocytosis pathway leading to pH and redox‐sensitive release kinetics. The superior FR‐targeted cytotoxicity is evaluated by the nanocarrier in comparison with US Food and Drug Administration (FDA)‐approved liposomal Dox conjugate, Lipodox. Moreover, TNEDS exhibits theranostic features through caspase‐mediated apoptosis and envisages high surface plasmon resonance enabling the nanoconstruct as a promising surface enhanced Raman scattering (SERS) nanotag. Minuscule changes in the biochemical components inside cells exerted by the TNEDS along with the Dox release are evaluated explicitly in a time‐dependent fashion using bimodal SERS/fluorescence nanoprobe. Finally, TNEDS displays superior antitumor response in FR‐positive ascites as well as solid tumor syngraft mouse models. Therefore, this futuristic TNEDS is expected to be a potential alternative as a clinically relevant theranostic nanomedicine to effectively combat neoplasia.     

Autonomous Magnetic Microrobots by Navigating Gates for Multiple Biomolecules Delivery

The precise delivery of biofunctionalized matters is of great interest from the fundamental and applied viewpoints. In spite of significant progress achieved during the last decade, a parallel and automated isolation and manipulation of rare analyte, and their simultaneous on‐chip separation and trapping, still remain challenging. Here, a universal micromagnet junction for self‐navigating gates of microrobotic particles to deliver the biomolecules to specific sites using a remote magnetic field is described. In the proposed concept, the nonmagnetic gap between the lithographically defined donor and acceptor micromagnets creates a crucial energy barrier to restrict particle gating. It is shown that by carefully designing the geometry of the junctions, it becomes possible to deliver multiple protein‐functionalized carriers in high resolution, as well as MCF‐7 and THP‐1 cells from the mixture, with high fidelity and trap them in individual apartments. Integration of such junctions with magnetophoretic circuitry elements could lead to novel platforms without retrieving for the synchronous digital manipulation of particles/biomolecules in microfluidic multiplex arrays for next‐generation biochips.     

Heat and mass transfer characteristics of radiative hybrid nanofluid flow over a stretching sheet with chemical reaction

Unsteady magnetohydrodynamic heat and mass transfer analysis of hybrid nanoliquid flow over a stretching surface with chemical reaction, suction, slip effects, and thermal radiation is analyzed in this study. A combination of alumina (Al₂O₃) and titanium oxide (TiO₂) nanoparticles are taken as hybrid nanoparticles and water is considered as the basefluid. Using the similarity transformation method, the governing equations are changed into a system of ordinary differential equations. These equations together with boundary conditions are numerically evaluated by using the Finite element method. The influence of various pertinent parameters on the profiles of fluids concentration, temperature, and velocity is calculated and the outcomes are plotted through graphs. The values of nondimensional rates of heat transfer, mass transfer, and velocity are also analyzed and the results are depicted in tables. Temperature sketches of hybrid nanoliquid intensified in both the steady and unsteady cases as the volume fraction of both nanoparticles rises.