Adsorption of isoniazid onto sepiolite–palygorskite group of clays: An IR study

The adsorption of isoniazid (INH) on sepiolite, loughlinite (natural Na-sepiolite) and palygorskite from Anatolia was investigated by FT-IR spectroscopy. Experimental results indicated that INH molecules, adsorbed on sepiolite–palygorskite group of clays, are coordinated to surface hydroxyls by H-bonding interaction through the pyridine ring nitrogen lone pairs. Moreover, some of the adsorbed INH molecules may enter the interior channels of the sepiolite–palygorskite structure and involve H-bonding interaction with zeolitic water. Some intensity and frequency changes in the OH stretching band of surface hydroxyls (Si–OH) of the INH-treated sepiolite and loughlinite were observed. However, this band is found to be less affected by the adsorption of isoniazid in the case of palygorskite, probably because the surface Si–OH groups in palygorskite appear to be less abundant than in sepiolite or loughlinite.     

Elements of Design‐Based Science Activities That Affect Students' Motivation

The primary purpose of this study was to examine the ways in which a 12‐week afterschool science and engineering program affected middle school students' motivation to engage in science and engineering activities. We used current motivation research and theory as a conceptual framework to assess 14 students' motivation through questionnaires, structured interviews, and observations. Students reported that during the activities they perceived that they were empowered to make choices in how to complete things, the activities were useful to them, they could succeed in the activities, they enjoyed and were interested in the hands‐on activities and some presentations, they felt cared for by the facilitators and received help when they were stuck or confused, and they put forth effort. Based on our examination of data across our three data sources, we identified motivating opportunities that were provided to students during the activities. These motivating opportunities can serve as examples to help both formal and informal science educators better connect motivation theory to practice so that they can create motivating opportunities for students. Furthermore, this study provides a methodological example of how students' motivation can be examined during the context of authentic science and engineering instruction.     

New ring-like models and ab initio DFT study of the medium-range structures,energy and electronic properties of GeSe2 glass

Ab initio DFT calculations were performed on Ge_nSe_m nanoclusters (n?=?2, 3, 5, 6, 12; m?=?6–9, 14, 16, 30) that represent the local structure of GeSe₂ glass and on some ‘defect’ Ge_nSe_m clusters that are thought to be related to the inhomogeneity of the structure at the nanoscale. The optimal geometries, total energies and their derivatives as well as the electronic properties of Ge_nSe_m nanoclusters were calculated using traditional DFT method. In addition, the TD-DFT method has been applied to calculate the electronic band gaps of the clusters. The calculated physico-chemical properties of Ge_nSe_m nanoclusters and their couplings with the local-and medium-range order structure formations in GeSe₂ glass are analysed and discussed.     

Wave shaping through finite electromagnetic bandgap structure

Transmission mechanisms and wave steering under localized feeding conditions through a finite electromagnetic bandgap structure are investigated both experimentally and theoretically. The artificial propagating medium consists of a two-dimensional metallic wire structure dimensioned for millimetre wave operation. By analogy with electron propagation in semiconductor heterostructures, the signatures of ‘modal‘ and ‘fluid‘ propagation regimes are experimentally demonstrated. Data are then analysed through electric field patterns calculated by means of a three-dimensional solver of Maxwell‘s equations.     

Highly coherent terahertz wave generation with a dual-frequency Brillouin fiber laser and a 1.55 μm photomixer

Thanks to a portable dual-frequency Brillouin fiber laser and a 1.55 μm photomixer, we report the generation of a highly coherent kilohertz level submillimeter wave emission. Low-cost telecommunications components are used to achieve very simple source architecture. The photomixer is composed of a unitravelling carrier photodiode integrated with an antenna. An emission at 316 GHz is observed and analyzed thanks to heterodyne detection with a signal-to-noise ratio >65 dB and a ~1 kHz linewidth. The phase noise of the proposed source has the same performance at 1.7 and 316 GHz. We show that this source has comparable or better phase noise compared to electrical oscillators and the tunability is much wider.     

Effects of ultrasonic energy on dyeing of polyamide (microfibre)/Lycra blends

Although ultrasonic energy is widely used cleaning and degreasing of parts and assemblies in automotive and other industries, the use of ultrasonic energy in an industrial scale for textile washing is very new. This is due to the complexity of controlling the combination of chemical and mechanical effects, whereas with degreasing of machine parts only the mechanical effects is applied. The use of ultrasonic energy in dyeing PA/Lycra fabrics with reactive dyes has been studied spectrophotometrically in this work. PA/Lycra (85/15) blends have been dyed using conventional and ultrasonic dyeing techniques with three reactive dyes containing different chromophore and reactive groups. The dyeing carried out conventionally and by the use of ultrasonic techniques. The results were compared in terms of percentage exhaustion; total dye transferred to the washing bath after dyeing and the fastness properties.     

Effects of ultrasonic energy on the wash fastness of reactive dyes

The field of ultrasonic is still making strides towards perfection, but already many applications of ultrasonic energy have been found in science and technology. There is also a field called sonochemistry where ultrasonic energy is used to create some chemical and mechanical effects on matter immersed or solved in liquids. It was presumed that ultrasonic textile washing could be a competitive alternative to conventional textile washing techniques; and as such the following experiments were conducted. In this study, the effects of ultrasonic energy on the wash fastness of reactive dyes, which have three different reactive groups, were investigated. After dyeing with the conventional method, the samples were applied with three types of washing processes simultaneously (conventional, ultrasonic probe and ultrasonic bath) and comparisons were made. Three different fixing agents were used in the washing processes. Colourfastness, staining fastness, magnitude of total colour difference (DeltaE) and lightness difference of the colour (DeltaL) values of dyed samples were measured.     

Confinement of THz surface waves on the subwavelength size metal waveguide

We investigate surface plasmon waves propagating on planar Goubau lines, so-called Goubau modes, using a guided-wave terahertz spectroscopy system based on a freely positionable electrooptic probe. We show the radial nature of the Goubau mode and its confinement around the Goubau line over a few tenths of microns (??/10).