Gas-mediated charged particle beam processing of nanostructured materials

Gas mediated processing under a charged particle (electron or ion) beam enables direct-write, high resolution surface functionalization, chemical dry etching and chemical vapor deposition of a wide range of materials including catalytic metals, optoelectronic grade semiconductors and oxides. Here we highlight three recent developments of particular interest to the optical materials and nanofabrication communities: fabrication of self-supporting, three dimensional, fluorescent diamond nanostructures, electron beam induced deposition (EBID) of high purity materials via activated chemisorption, and post-growth purification of nanocrystalline EBID-grown platinum suitable for catalysis applications. © 2014 SPIE

Guar gum: A novel binder for ceramic extrusion

Ceramic honeycomb extrusion is a technique capable of attaining high strength, porous ceramics. However, challenges prevent the realisation of its potential. These include the design of an intricate honeycomb die and the formulation of an extrudable paste. The present study addresses the latter by using guar gum (GG) as a binder. GG was rationally selected because hydrogels thereof exhibit strong shear-thinning and high stiffness properties, which are required for extrusion. Rheological analyses demonstrated ceramic pastes with similar qualities were achieved, with hydroxyapatite (HA) used as the model ceramic. The shear stiffness modulus of HA pastes was determined as 8.4 MPa with a yield stress of 1.1 kPa. Moreover, this was achieved with GG as the sole additive, which further facilitates the overall fabrication process. The binder extraction notably occurred at relatively low temperatures when other high molecular weight polymers demand temperatures above 1000 °C; therefore the latter precludes the use of ceramics with low sintering onset. The process culminated in a porous HA scaffold with similar porosity to that of a commercial HA graft, but with higher compressive strength. Lastly, the study notes that the biological and water-soluble properties of GG can broaden its application into other ceramic fabrication processes

Localization of Narrowband Single Photon Emitters in Nanodiamonds

© 2016 American Chemical Society. Diamond nanocrystals that host room temperature narrowband single photon emitters are highly sought after for applications in nanophotonics and bioimaging. However, current understanding of the origin of these emitters is extremely limited. In this work, we demonstrate that the narrowband emitters are point defects localized at extended morphological defects in individual nanodiamonds. In particular, we show that nanocrystals with defects such as twin boundaries and secondary nucleation sites exhibit narrowband emission that is absent from pristine individual nanocrystals grown under the same conditions. Critically, we prove that the narrowband emission lines vanish when extended defects are removed deterministically using highly localized electron beam induced etching. Our results enhance the current understanding of single photon emitters in diamond and are directly relevant to fabrication of novel quantum optics devices and sensors

Robust multicolor single photon emission from point defects in hexagonal boron nitride

© 2017 IEEE. We demonstrates engineering of quantum emitters in hBN multi-layers using either electron beam irradiation or annealing. The defects exhibit a broad range of multicolor room-temperature single photon emissions across the visible and the near-infrared ranges

IN SILICO PHARMACOKINETICS AND MOLECULAR DOCKING OF THREE LEADS ISOLATED FROM TARCONANTHUS CAMPHORATUS L.

Objective: To investigate the pharmacokinetic and toxicity profiles and spectrum of biological activities of three phytochemicals isolated from Tarconanthus camphoratus L. Methods: Several integrated web based in silico pharmacokinetic tools were used to estimate the druggability of Hispidulin, Nepetin and Parthenolide. Afterward, the structural based virtual screening for the three compounds' potential targets was performed using PharmMapper online server. The molecular docking was conducted using Auto-Dock 4.0 software to study the binding interactions of these compounds with the targets predicted by PharmMapper server. Results: The permeability properties for all compounds were found within the limit range stated for Lipinski׳s rule of five. Only Parthenolide proved to be able to penetrate through blood brain barrier. Isopentenyl-diphosphate delta-isomerase (IPPI), uridine-cytidine kinase-2 (UCK-2) and the mitogen-activated protein kinase kinase-1 (MEK-1) were proposed as potential targets for Hispidulin, Nepetin and Parthenolide, respectively. Nepetin and Parthenolide were predicted to have anticancer activities. The activity of Nepetin appeared to be mediated through UCK-2 inhibition. On the other hand, inhibition of MEK-1 and enhancement of TP53 expression were predicted as the anticancer mechanisms of Parthenolide. The three compounds showed interesting interactions and satisfactory binding energies when docked into their relevant targets. Conclusion: The ADMET profiles and biological activity spectra of Hispidulin, Nepetin and Parthenolide have been addressed. These compounds are proposed to have activities against a variety of human aliments such as tumors, muscular dystrophy, and diabetic cataracts.Keywords: Tarconanthus camphoratus L., Hispidulin, Nepetin, Parthenolide, In silico pharmacokinetic, Molecular docking, PharmMapper server, and Auto-Dock 4.0 softwareÂ

Single photon emission from plasma treated 2D hexagonal boron nitride

© 2018 The Royal Society of Chemistry. Artificial atomic systems in solids are becoming increasingly important building blocks in quantum information processing and scalable quantum nanophotonic networks. Amongst numerous candidates, 2D hexagonal boron nitride has recently emerged as a promising platform hosting single photon emitters. Here, we report a number of robust plasma and thermal annealing methods for fabrication of emitters in tape-exfoliated hexagonal boron nitride (hBN) crystals. A two-step process comprising Ar plasma etching and subsequent annealing in Ar is highly robust, and yields an eight-fold increase in the concentration of emitters in hBN. The initial plasma-etching step generates emitters that suffer from blinking and bleaching, whereas the two-step process yields emitters that are photostable at room temperature with emission wavelengths greater than ∼700 nm. Density functional theory modeling suggests that the emitters might be associated with defect complexes that contain oxygen. This is further confirmed by generating the emitters via annealing hBN in air. Our findings advance the present understanding of the structure of quantum emitters in hBN and enhance the nanofabrication toolkit needed to realize integrated quantum nanophotonic circuits

Development of new thiazolidine-2,4-dione hybrids as aldose reductase inhibitors endowed with antihyperglycaemic activity: design, synthesis, biological investigations, and in silico insights

This research study describes the development of new small molecules based on 2,4-thiazolidinedione (2,4-TZD) and their aldose reductase (AR) inhibitory activities. The synthesis of 17 new derivatives of 2,4-TZDs hybrids was feasible by incorporating two known bioactive scaffolds, benzothiazole heterocycle, and nitro phenacyl moiety. The most active hybrid (8b) was found to inhibit AR in a non-competitive manner (0.16 µM), as confirmed by kinetic studies and molecular docking simulations. Furthermore, the in vivo experiments demonstrated that compound 8b had a significant hypoglycaemic effect in mice with hyperglycaemia induced by streptozotocin. Fifty milligrams per kilogram dose of 8b produced a marked decrease in blood glucose concentration, and a lower dose of 5 mg/kg demonstrated a noticeable antihyperglycaemic effect. These outcomes suggested that compound 8b may be used as a promising therapeutic agent for the treatment of diabetic complications

Reforming Fiscal Institutions in Resource-Rich Arab Economies: Policy Proposals

This paper traces the evolution of fiscal institutions of Resource Rich Arab Economies (RRAEs) over time since their pre-oil days, through the discovery of oil to their build-up of oil exports. It then identifies challenges faced by RRAEs and variations in their severity among the different countries over time. Finally, it articulates specific policy reforms, which, if implemented successfully, could help to overcome these challenges. In some cases, however, these policy proposals may give rise to important trade-offs that will have to be evaluated carefully in individual cases

Demographic transition and the real exchange rate in Australia: An empirical investigation

This article utilizes the empirical findings that age structure of the population affects saving, investment and capital flow and hypothesizes that age structure influences the real exchange rate. Based on this link, an empirical model is specified for Australia and estimated with annual data for the period 1970–2011. An autoregressive distributed lag model of cointegration indicates that Australia's real exchange rate is cointegrated with its productivity differential and the relative share of young dependents (0–14 years) in the population. Long-run estimates show that young cohort has an appreciating influence on the real exchange rate. Also, the short-run adjustment is substantial, with more than 65% of the disequilibrium corrected in a year