Effect of concept map supported teaching approaches from rules to sample and sample to rules to grammar teaching

2nd World Conference on Educational Sciences (WCES-2010) -- FEB 04-08, 2010 -- Bahceschir Univ, Istanbul, TURKEYWOS: 000282002803154In this study, the effect of approach from rules-to-sample and sample-to-rules to the teaching of grammar subjects has been analysed. While treating grammar subjects from rules-to-sample and sample-to-rules learning-teaching process in both approaches are supported by the concept map. Application has been maintained for six weeks and data were obtained by applying more assesment instruments to students taking part in experimental and control groups. In practice, pretest - post test model was applied. At the end of the learning-teaching process, achievements of students have been assesed by a variety of assesment instruments, the data gathered has been analysed with the help of statistical techniques such as one-way variance analysis, "t" test, arithmetic averages. 96 students at the level of fourth grade participated the application process; 30 of them participated application from rules-to-sample; 33 students participated application from sample to rules in an active manner, and 33 students in the control group continued to traditional teaching. Assesments have been analysed and results have been compared. As a result of research, results that participants obtained were compared in terms of variables such as students' participation level to teaching process, the time students spent for learning, students' rememberance level of what they have learned. In terms of foregoing variables, meaningful results were obtained in favor of approach from sample to rule. By taking into account of the results obtained, some suggestions have been done aiming to teaching done by teaching strategies and concept maps. (C) 2010 Elsevier Ltd. All rights reserved

Flexible and mechanically stable antireflective coatings from nanoporous organically modified silica colloids

Cataloged from PDF version of article.We report the preparation of flexible and mechanically stable antireflective organically modified silica (ormosil) coatings at ambient conditions. Thin films are obtained from colloidal suspensions of ormosil gels which are prepared using methyltrimethoxysilane (MTMS) and tetraethyl orthosilicate (TEOS) monomers. The ormosil suspensions are directly applicable and suitable for the large-area deposition of nanoporous ormosil thin films. The nanoporosity of the films can be tuned by changing the monomer ratio of the starting solution. Thin films on flexible substrates retain their antireflective properties even after 100 cycles of excessive bending without a significant change in transmission. Furthermore, the films remained intact after water dripping and adhesive tape tests. In addition, thin films on glass substrates are found to exhibit antifogging properties after annealing at 600 degrees C for 30 min. The ease of fabrication and multifunctionality of these films make them ideal coatings for flexible electronic and optoelectronic devices, sensors, and solar cells

Large and dynamical tuning of a chalcogenide Fabry-Perot cavity mode by temperature modulation

Cataloged from PDF version of article.Te-enriched chalcogenide glass Ge15As25Se15Te45 (GAST) is synthesized, thermo-optically characterized and used to fabricate a one dimensional photonic crystal cavity mode that is dynamically and reversibly tuned by temperature modulation. The optical cavity mode is designed using GAST and As2S3 glasses after fully determining their temperature dependence of the complex refractive indices in the visible and near infrared spectrum using spectroscopic ellipsometry. By making use of the very large thermo-optic coefficient (dn/dT = 4x10(-4)/degrees C) of GAST glass at 1.2 mu m, the cavity mode of the multilayer was tuned reversibly more than 16 nm, which is, to the best of our knowledge, an order of magnitude larger for this kind of cavity modulation. Wide and dynamical spectral tuning of low bandgap chalcogenide glasses via temperature modulation can be utilized in photonic crystal based integrated optics, quantum dot resonance matching, solid state and gas laser components, and infrared photonic crystal fibers. (C) 2010 Optical Society of Americ

Room temperature large-area nanoimprinting for broadband biomimetic antireflection surfaces

Cataloged from PDF version of article.Ordered arrays of subwavelength hydrogen silsesquioxane (HSQ) nanorods on glass substrates are fabricated using room temperature nanoimprint lithography and anodized aluminum oxide membranes. Moth-eye type nanorod arrays exhibited superior omnidirectional antireflection characteristics in visible wavelengths. The ellipsometric measurements revealed that average specular reflection is remaining below 1% up to 55 degrees incidence angles. Transmission measurements at normal incidence resulted in significant increase in transmitted light intensity with respect to plain glass. Simulations showed that up to 99% transmission could be obtained from double sided tapered HSQ nanorod arrays on HSQ thin film and glass substrates. Achieving large-area, broadband and omnidirectional antireflective surfaces on glass pave the way for applications including photovoltaics. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3657766

Highly Transparent, Flexible, and Thermally Stable Superhydrophobic ORMOSIL Aerogel Thin Films

Cataloged from PDF version of article.We report preparation of highly transparent, flexible, and thermally stable superhydrophobic organically modified silica (ORMOSIL) aerogel thin films from colloidal dispersions at ambient conditions. The prepared dispersions are suitable for large area processing with ease of coating and be:ing directly applicable without requiring any pre- or post-treatment on a variety of surfaces including glass, wood, and plastics. ORMOSIL films exhibit and retain superhydrophobic behavior up to 500 degrees C and even on bent flexible substrates. The surface of the films can be converted from superhydrophobic (contact angle of 179.9 degrees) to superhydrophilic (contact angle of <5 degrees) by calcination at high temperatures. The wettability of the coatings can be changed by tuning the calcination temperature and duration. The prepared films also exhibit low refractive index and high porosity making them suitable as multifunctional coatings for many application fields including solar cells, flexible electronics, and lab on papers

Multi-Stage Nozzle-Shape Optimization For Pulsed Hydrogen-Air Detonation Combustor

hermal engines based on pressure gain combustion offer new opportunities to generate thrust with enhanced efficiency and relatively simple machinery. The sudden expansion of detonation products from a single-opening tube yields thrust, although this is suboptimal. In this article, we present the complete design optimization strategy for nozzles exposed to detonation pulses, combining unsteady Reynolds-averaged Navier-Stokes solvers with the accurate modeling of the combustion process. The parameterized shape of the nozzle is optimized using a differential evolution algorithm to maxi­ mize the force at the nozzle exhaust. The design of experiments begins with a first optimization considering steady-flow conditions, subsequently followed by a refined optimization for transient supersonic flow pulse. Finally, the optimized nozzle performance is assessed in three dimensions with unsteady Reynolds-averaged Navier-Stokes capturing the deflagration-to-detonation transition of a stoichiometric, premixed hydrogen-air mixture. The optimized nozzle can deliver 80% more thrust than a standard detonation tube and about 2% more than the optimized results assuming steady-flow operation. This study proposes a new multi-fidelity approach to optimize the design of nozzles exposed to transient operation, instead of the traditional methods proposed for steady-flow operation

Template free preparation of nanoporous organically modified silica thin films on flexible substrates

Cataloged from PDF version of article.We report the preparation and characterization of nanoporous organically modified silica (ormosil) thin films at room temperature and neutral pH conditions from homogeneous methyl silsesquioxane (MSQ) gels. Universally applicable and stable colloidal ormosil suspensions are prepared from the gels by sonication and coated to the substrates including glass, paper and plastics. The nanoporosity and thickness of the films can be tuned, which makes them suitable for certain applications including sensing, functional coatings, and low-dielectric materials. We demonstrate the antireflection property of the films on glass, cellulose acetate (CA) and polyetherimide (PEI) substrates. The films on CA and PEI retain their antireflection property after multiple bending cycles. Furthermore, films are intrinsically hydrophobic, over a wide pH range, with static contact angles up to 143° on paper and 123° on glass and CA. Producing nanoporous ormosil thin films on flexible substrates may expand their use in low cost electronic, optical devices and sensors, and lab-on-paper applications

All-chalcogenide glass omnidirectional photonic band gap variable infrared filters

Cataloged from PDF version of article.We report on the design, fabrication, and characterization of spatially variable infrared photonic band gap filter that consists of thermally evaporated, high refractive index contrast, amorphous chalcogenide glass multilayers. Due to graded thickness structure, the filter exhibits a position dependent stop band and a cavity mode ranging from 1.8 to 3.4 μm wavelengths. Reflection measurements on the variable filter agree well with theoretical calculations. These results pave the way to low-loss infrared mirrors, filters, spectral imaging, and miniaturized spectrometers at infrared region. © 2009 American Institute of Physics

Template-Directed Synthesis of Silica Nanotubes for Explosive Detection

Cataloged from PDF version of article.Fluorescent porous organic-inorganic thin films are of interest of explosive detection because of their vapor phase fluorescence quenching property. In this work, we synthesized fluorescent silica nanotubes using a biomineralization process through self-assembled peptidic nanostructures. We designed and synthesized an amyloid-like peptide self-assembling into nanofibers to be used as a template for silica nanotube formation. The amine groups on the peptide nanofibrous system were used for nucleation of silica nanostructures. Silica nanotubes were used to prepare highly porous surfaces, and they were doped with a fluorescent dye by physical adsorption for explosive sensing. These porous surfaces exhibited fast, sensitive, and highly selective fluorescence quenching against nitro-explosive vapors. The materials developed in this work have vast potential in sensing applications due to enhanced surface area. © 2011 American Chemical Society