Simple non-basic solution route for the preparation of zinc oxide hollow spheres

Despite considerable efforts undertaken in a rapidly developing area of materials research, controlled synthesis of nanostructured ZnO is still a matter of intensive research. Herein, we report a facile base free approach for the fabrication of nanostructured ZnO hollow spheres. In the synthesis, ethylene glycol has been introduced as solvent and crystal-growth modifier and zinc acetate has been used as zinc precursor and also a source of soft template. ZnO nanoparticles of diameter â¼25 nm are assembled into highly regular hollow spheres. The powder X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL) and UV-visible spectroscopy have been used to characterize the crystal structure, morphology, composition and optical properties. Powder XRD pattern of ZnO confirms the formation of the wurtzite structure. Presence of oxygen deficiency in the prepared ZnO product is revealed by Raman and EDS studies. Strong emission at 422 nm with three weak emissions at 400, 484 and 529 nm were observed by PL spectrum. The growth mechanism for the formation of ZnO hollow spheres has been discussed on the basis of the growth model for the polar ZnO crystals. © 2012 Elsevier B.V

Juvenile Nasopharyngeal Angiofibroma - A Case Report

15 year old male who presented with a 6 month history of nasal obstruction and recurrent nasal bleeding. He had had about ten episodes of epistaxis in the 3 months. Examination revealed that vital signs were essentially within normal limits.The nasal cavity revealed fresh blood in the right nasal cavity but the bleeding site could not be visualized. An impression of epistaxis secondary rhinosinusitis was made

Recent Advances in Dental Composites: An Overview

Composite resins are widely used aesthetic materials in restorative dentistry. These materials were introduced to overcome the inherent shortcomings of amalgam restorative materials. Dental amalgams are unesthetic and toxic. Earlier composites lack in mechanical properties to withstand the masticatory forces. Various filler particles have been added to composite resins to improve their physical and mechanical properties.  Filled composite resins exhibit high compressive strength, abrasion resistance, ease of application and high translucency. Depending on the filler size and shapes, various composites have been developed until now. This article is a review of numerous types of composites that are technologically advanced to modify their properties

Novel ethyl 2-(1-aminocyclobutyl)-5-(benzoyloxy)-6-hydroxy-pyrimidine-4-carboxylate derivatives: synthesis and anticancer activities

To explore the anticancer activity of 2, 4, 5, 6-substituted pyrimidines, several ethyl 2-(1-aminocyclobutyl)-5-(benzoyloxy)-6-hydroxy-pyrimidine-4-carboxylate derivatives associated with the different substituted aromatic/aliphatic carboxamides and sulfonamides were synthesized. Different groups and position on phenyl ring attached to the carboxamide and sulfonamide of the pyrimidine led to two set of compounds. Their chemical structures were confirmed by IR,1H NMR and LC/MS analysis. Cytotoxicity of all the synthesized compounds were examined on human leukemia celllines (K562 and CEM). The preliminary results showed most of the derivatives exhibited good antitumor activity. Compound with para chloro substitution among carboxamides and compound with meta dichloro substitution among sulphonamidesexhibited significant antitumor activity with IC50 value of 14.0 μM and 15.0 μM respectively against K562cell line. For comparison among electron donating groups between carboxamides and sulfonamides, compounds with para tert-butyl substitution were chosen for further studies. Cell cycle analysis suggests that both tert-butyl substituted compounds are able to induce apoptosis

Flowering and fruit set in vanilla (Vanilla planifolia Andr.)

Cultivation of vanilla (Vanilla planifolia Andr.) is becoming increasingly popular in recent years in the hill zone of Karnataka, India. &nbsp

Comparison of the photocatalytic degradation of trypan blue by undoped and silver-doped zinc oxide nanoparticles

Zinc oxide (ZnO) and silver doped zinc oxide (ZnO:Ag) nanoparticles were prepared using nitrates of zinc and silver as oxidizers and ethylene diaminetetraacetic acid (EDTA) as a fuel via low-temperature combustion synthesis (LCS) at 500 degrees C. X-ray diffraction (XRD) pattern indicates the presence of silver in the hexagonal wurtzite structure of ZnO. Fourier transform infrared (FTIR) spectrum indicates the presence of Ag-Zn-O stretching vibration at 510 cm(-1). Transmission electron microscopy (TEM) images shows that the average particle size of ZnO and ZnO:Ag nanoparticles were found to be 58 nm and 52 nm, respectively. X-ray photoelectron spectroscopy (XPS) data clearly indicates the presence of Ag in ZnO crystal lattice. The above characterization techniques indicate that the incorporation of silver affects the structural and optical properties of ZnO nanoparticles. ZnO:Ag nanoparticles exhibited 3% higher photocatalytic efficiency than pure ZnO nanoparticles. ZnO:Ag nanoparticles show better photocatalytic activity for the degradation of trypan blue (TrB) compared to undoped ZnO nanoparticles. (C) 2014 Elsevier Ltd. All rights reserved

Aerodynamic and Heat Transfer Studies on HUB sections of a high pressure turbine blade: summary report

The stator and rotor blade hub sections designed for a high pressure turbine stage were studied in detail for their aerodynamic and heat transfer characteristics . The profile sections were tested in the National Aeronautical Laboratory Cascade Tunnels over a range of exit flow Mach numbers . The flow field and heat transfer characteristics of the cascades were also code based on Denton's method and the boundary layer code incorporating K- E turbulence model. The results indicated that there was a scope for improving the blade profile sections for high Mach number applications

Iridium-doping as a strategy to realize visible light absorption and p-type behavior in BaTiO3

BaTiO3 is typically a strong n-type material with tuneable optoelectronic properties via doping and controlling the synthesis conditions. It has a wide band gap that can only harness the ultraviolet region of the solar spectrum. Despite significant progress, achieving visible-light absorbing BTO with tuneable carrier concentration has been challenging, a crucial requirement for many applications. In this work, a p-type BTO with visible-light absorption is realized via iridium doping. Detailed analysis using advanced spectroscopy tools and computational electronic structure analysis is used to rationalize the n- to p-type transition after Ir doping. Results offered mechanistic insight into the interplay between the dopant site occupancy, the dopant position within the band gap, and the defect chemistry affecting the carrier concentration. A decrease in the Ti3+ donor levels concentration and the mutually correlated oxygen vacancies upon Ir doping is attributed to the p-type behavior. Due to the formation of Ir3+ or Ir4+ in-gap energy levels within the forbidden region, the optical transition can be elicited from or to such levels resulting in visible-light absorption. This newly developed Ir-doped BTO can be a promising p-type perovskite-oxide with imminent applications in solar fuel generation, spintronics and optoelectronics.Comment: 21 pages, 8 figure

Self Assembly and Properties of C:WO3 Nano-Platelets and C:VO2/V2O5 Triangular Capsules Produced by Laser Solution Photolysis

Laser photolysis of WCl6 in ethanol and a specific mixture of V2O5 and VCl3 in ethanol lead to carbon modified vanadium and tungsten oxides with interesting properties. The presence of graphene’s aromatic rings (from the vibrational frequency of 1,600 cm−1) together with C–C bonding of carbon (from the Raman shift of 1,124 cm−1) present unique optical, vibrational, electronic and structural properties of the intended tungsten trioxide and vanadium dioxide materials. The morphology of these samples shows nano-platelets in WOx samples and, in VOx samples, encapsulated spherical quantum dots in conjunction with fullerenes of VOx. Conductivity studies revealed that the VO2/V2O5 nanostructures are more sensitive to Cl than to the presence of ethanol, whereas the C:WO3 nano-platelets are more sensitive to ethanol than atomic C