Search results for: graded photonic crystal

Authors: Danilo A. F. Fontes, Magaly A. M.Lyra, Maria L. C. Moura, Leslie R. M. Ferraz, Salvana P. M. Costa, Amanda C. Q. M. Vieira, Larissa A. Rolim, Giovanna C. R. M. Schver, Ping I. Lee, Severino Alves-Júnior, José L. Soares-Sobrinho, Pedro J. Rolim-Neto

Abstract:

Efavirenz (EFV) is a first-choice drug in antiretroviral therapy with high efficacy in the treatment of infection by Human Immunodeficiency Virus, which causes Acquired Immune Deficiency Syndrome (AIDS). EFV has low solubility in water resulting in a decrease in the dissolution rate and, consequently, in its bioavailability. Among the technological alternatives to increase solubility, the Lamellar Double Hydroxides (LDH) have been applied in the development of systems with poorly water-soluble drugs. The use of analytical techniques such as X-Ray Diffraction (XRD), Infrared Spectroscopy (IR) and Differential Scanning Calorimetry (DSC) allowed the elucidation of drug interaction with the lamellar compounds. The objective of this work was to characterize and develop the binary systems with EFV and LDH in order to increase the solubility of the drug. The LDH-CaAl was synthesized by the method of co-precipitation from salt solutions of calcium nitrate and aluminum nitrate in basic medium. The systems EFV-LDH and their physical mixtures (PM) were obtained at different concentrations (5-60% of EFV) using the solvent technique described by Takahashi & Yamaguchi (1991). The characterization of the systems and the PM’s was performed by XRD techniques, IR, DSC and dissolution test under non-sink conditions. The results showed improvements in the solubility of EFV when associated with LDH, due to a possible change in its crystal structure and formation of an amorphous material. From the DSC results, one could see that the endothermic peak at 173°C, temperature that correspond to the melting process of EFZ in the crystal form, was present in the PM results. For the EFZ-LDH systems (with 5, 10 and 30% of drug loading), this peak was not observed. XRD profiles of the PM showed well-defined peaks for EFV. Analyzing the XRD patterns of the systems, it was found that the XRD profiles of all the systems showed complete attenuation of the characteristic peaks of the crystalline form of EFZ. The IR technique showed that, in the results of the PM, there was the appearance of one band and overlap of other bands, while the IR results of the systems with 5, 10 and 30% drug loading showed the disappearance of bands and a few others with reduced intensity. The dissolution test under non-sink conditions showed that systems with 5, 10 and 30% drug loading promoted a great increase in the solubility of EFV, but the system with 10% of drug loading was the only one that could keep substantial amount of drug in solution at different pHs.

Keywords: Efavirenz, Lamellar Double Hydroxides, Pharmaceutical Techonology, Solubility

Procedia PDF Downloads 583

Authors: R. Bennai, H. Ait Atmane, H. Fourne, B. Ayache

Abstract:

In this work, an analytical approach using a refined theory of hyperbolic shear deformation of a beam was developed to study the buckling of graduated sandwiches beams under different boundary conditions. The effects of transverse shear strains and the transverse normal deformation are considered. The constituent materials of the beam are supposed gradually variable depending on the height direction based on a simple power distribution law in terms of the volume fractions of the constituents; the two materials with which we worked are metals and ceramics. The core layer is taken homogeneous and made of an isotropic material; while the banks layers consist of functionally graded materials with a homogeneous fraction compared to the middle layer. In the end, illustrative examples are presented to show the effects of changes in different parameters such as (material graduation, the stretching effect of the thickness, boundary conditions and thickness ratio-length) on the vibration free of an FGM sandwich beams.

Keywords: FGM materials, refined shear deformation theory, stretching effect, buckling

Procedia PDF Downloads 178

Authors: Nadine Ali Hassan, Ngoc Son Nguyen, Didier Marot, Fateh Bendahmane

Abstract:

This paper aims at presenting a study of the effect of scalping methods on the mechanical properties of coarse soils by resorting to numerical simulations based on the discrete element method (DEM) and experimental triaxial tests. Two reconstitution methods are used, designated as scalping method and substitution method. Triaxial compression tests are first simulated on a granular materials with a grap graded particle size distribution by using the DEM. We study the effect of these reconstitution methods on the stress-strain behavior of coarse soils with different fine contents and with different ways to control the densities of the scalped and substituted materials. Experimental triaxial tests are performed on original mixtures of sands and gravels with different fine contents and on their corresponding scalped and substituted samples. Numerical results are qualitatively compared to experimental ones. Agreements and discrepancies between these results are also discussed.

Keywords: coarse soils, mechanical behavior, scalping, replacement, triaxial devices

Procedia PDF Downloads 207

Authors: Sito Ismanti, Noriyuki Yasufuku

Abstract:

Cement utilization to improve the properties of soil is a well-known method applied in field. However, its addition in large quantity must be controlled. This study presents utilization of natural and environmental-friendly material mixed with small amount of cement content in soil improvement, i.e. bamboo chips. Absorbability, elongation, and flatness ratio of bamboo chips were examined to investigate and understand the influence of its characteristics in the mixture. Improvement of dilation behavior as a problem of loose and poorly graded sand soil is discussed. Bamboo chips are able to improve the permeability value that affects the dilation behavior of cemented sand soil. It is proved by the stress path as the result of triaxial compression test in the undrained condition. The effect of size and content variation of bamboo chips, as well as the curing time variation are presented and discussed.  

Keywords: bamboo chips, permeability, mechanical properties, triaxial compression

Procedia PDF Downloads 333

Authors: Marilou Cadatal-Raduban, Minh Hong Pham, Duong Van Pham, Tu Nguyen Xuan, Mui Viet Luong, Kohei Yamanoi, Toshihiko Shimizu, Nobuhiko Sarukura, Hung Dai Nguyen

Abstract:

There is a great deal of interest in developing all-solid-state tunable ultrashort pulsed lasers emitting in the ultraviolet (UV) region for applications such as micromachining, investigation of charge carrier relaxation in conductors, and probing of ultrafast chemical processes. However, direct short-pulse generation is not as straight forward in solid-state gain media as it is for near-IR tunable solid-state lasers such as Ti:sapphire due to the difficulty of obtaining continuous wave laser operation, which is required for Kerr lens mode-locking schemes utilizing spatial or temporal Kerr type nonlinearity. In this work, the transient cavity method, which was reported to generate ultrashort laser pulses in dye lasers, is extended to a solid-state gain medium. Ce:LiCAF was chosen among the rare-earth-doped fluoride laser crystals emitting in the UV region because of its broad tunability (from 280 to 325 nm) and enough bandwidth to generate 3-fs pulses, sufficiently large effective gain cross section (6.0 x10⁻¹⁸ cm²) favorable for oscillators, and a high saturation fluence (115 mJ/cm²). Numerical simulations are performed to investigate the spectro-temporal evolution of the broadband UV laser emission from Ce:LiCAF, represented as a system of two homogeneous broadened singlet states, by solving the rate equations extended to multiple wavelengths. The goal is to find the appropriate cavity length and Q-factor to achieve the optimal photon cavity decay time and pumping energy for resonator transients that will lead to ps UV laser emission from a Ce:LiCAF crystal pumped by the fourth harmonics (266nm) of a Nd:YAG laser. Results show that a single ps pulse can be generated from a 1-mm, 1 mol% Ce³⁺-doped LiCAF crystal using an output coupler with 10% reflectivity (low-Q) and an oscillator cavity that is 2-mm long (short cavity). This technique can be extended to other fluoride-based solid-state laser gain media.

Keywords: rare-earth-doped fluoride gain medium, transient cavity, ultrashort laser, ultraviolet laser

Procedia PDF Downloads 357

Authors: D. G. Piliposyan

Abstract:

Propagation of electro-elastic waves in a piezoelectric waveguide with finite stacks and a defect layer is studied using a modified transfer matrix method. The dispersion equation for a periodic structure consisting of unit cells made up from two piezoelectric materials with metallized interfaces is obtained. An analytical expression, for the transmission coefficient for a waveguide with finite stacks and a defect layer, that is found can be used to accurately detect and control the position of the passband within a stopband. The result can be instrumental in constructing a tunable waveguide made of layers of different or identical piezoelectric crystals and separated by metallized interfaces.

Keywords: piezoelectric layered structure, periodic phononic crystal, bandgap, bloch waves

Procedia PDF Downloads 225

Authors: T. Ito, K. Kawaguchi, R. Ohta

Abstract:

The purpose of this study is to provide a guideline to assist globally-minded companies in developing task-based English-language programs for their employees. After conducting an online self-assessment questionnaire comprised of 45 job-related tasks, we analyzed responses received from 3,000 Japanese company employees and developed a checklist that considered three areas: (i) the percentage of those who need to accomplish English-language tasks in their workplace (need for English), (ii) a five-point self-assessment score (task performance level), and (iii) the impact of previous task experience on perceived performance (experience factor). The 45 tasks were graded according to five proficiency levels. Our results helped us to create a core guideline that may assist companies in two ways: first, in helping determine which tasks employees with a certain English proficiency should be able to satisfactorily carry out, and secondly, to quickly prioritize which business-related English skills they would need in future English language programs.

Keywords: business settings, can-do statements, English language training programs, self-assessment, task experience

Procedia PDF Downloads 252

Authors: Saleh Gorji, Sahil Gulati, Ana Pakzad

Abstract:

Continuous electron diffraction tomography, also known as microcrystal electron diffraction (MicroED) or three-dimensional electron diffraction (3DED), is a powerful technique, which in combination with cryo-electron microscopy (cryo-ED), can provide atomic-scale 3D information about the crystal structure and composition of different classes of crystalline materials such as proteins, peptides, and small molecules. Unlike the well-established X-ray crystallography method, 3DED does not require large single crystals and can collect accurate electron diffraction data from crystals as small as 50 – 100 nm. This is a critical advantage as growing larger crystals, as required by X-ray crystallography methods, is often very difficult, time-consuming, and expensive. In most cases, specimens studied via 3DED method are electron beam sensitive, which means there is a limitation on the maximum amount of electron dose one can use to collect the required data for a high-resolution structure determination. Therefore, collecting data using a conventional scintillator-based fiber coupled camera brings additional challenges. This is because of the inherent noise introduced during the electron-to-photon conversion in the scintillator and transfer of light via the fibers to the sensor, which results in a poor signal-to-noise ratio and requires a relatively higher and commonly specimen-damaging electron dose rates, especially for protein crystals. As in other cryo-EM techniques, damage to the specimen can be mitigated if a direct detection camera is used which provides a high signal-to-noise ratio at low electron doses. In this work, we have used two classes of such detectors from Gatan, namely the K3® camera (a monolithic active pixel sensor) and Stela™ (that utilizes DECTRIS hybrid-pixel technology), to address this problem. The K3 is an electron counting detector optimized for low-dose applications (like structural biology cryo-EM), and Stela is also a counting electron detector but optimized for diffraction applications with high speed and high dynamic range. Lastly, data collection workflows, including crystal screening, microscope optics setup (for imaging and diffraction), stage height adjustment at each crystal position, and tomogram acquisition, can be one of the other challenges of the 3DED technique. Traditionally this has been all done manually or in a partly automated fashion using open-source software and scripting, requiring long hours on the microscope (extra cost) and extensive user interaction with the system. We have recently introduced Latitude® D in DigitalMicrograph® software, which is compatible with all pre- and post-energy-filter Gatan cameras and enables 3DED data acquisition in an automated and optimized fashion. Higher quality 3DED data enables structure determination with higher confidence, while automated workflows allow these to be completed considerably faster than before. Using multiple examples, this work will demonstrate how to direct detection electron counting cameras enhance 3DED results (3 to better than 1 Angstrom) for protein and small molecule structure determination. We will also show how Latitude D software facilitates collecting such data in an integrated and fully automated user interface.

Keywords: continuous electron diffraction tomography, direct detection, diffraction, Latitude D, Digitalmicrograph, proteins, small molecules

Procedia PDF Downloads 107

Authors: Fernando Martinez Soto, Gaetano Di Mino

Abstract:

The application of rubber into bituminous mixtures requires attention and care during mixing and compaction. Rubber modifies the properties because it reacts in the internal structure of bitumen at high temperatures changing the performance of the mixture (interaction process of solvents with binder-rubber aggregate). The main change is the increasing of the viscosity and elasticity of the binder due to the larger sizes of the rubber particles by dry process but, this positive effect is counteracted by short mixing times, compared to wet technology, and due to the transport processes, curing time and post-compaction of the mixtures. Therefore, negative effects as swelling of rubber particles, rebounding effect of the specimens and thermal changes by different expansion of the structure inside the mixtures, can change the mechanical properties of the rubberized blends. Based on the dry technology, different asphalt-rubber binders using devulcanized or natural rubber (truck and bus tread rubber), have served to demonstrate these effects and how to solve them into two dense-gap graded rubber modified asphalt concrete mixes (RUMAC) to enhance the stability, workability and durability of the compacted samples by Superpave gyratory compactor method. This paper specifies the procedures developed in the Department of Civil Engineering of the University of Palermo during September 2016 to March 2017, for characterizing the post-compaction and mix-stability of the one conventional mixture (hot mix asphalt without rubber) and two gap-graded rubberized asphalt mixes according granulometry for rail sub-ballast layers with nominal size of Ø22.4mm of aggregates according European standard. Thus, the main purpose of this laboratory research is the application of ambient ground rubber from scrap tires processed at conventional temperature (20ºC) inside hot bituminous mixtures (160-220ºC) as a substitute for 1.5%, 2% and 3% by weight of the total aggregates (3.2%, 4.2% and, 6.2% respectively by volumetric part of the limestone aggregates of bulk density equal to 2.81g/cm³) considered, not as a part of the asphalt binder. The reference bituminous mixture was designed with 4% of binder and ± 3% of air voids, manufactured for a conventional bitumen B50/70 at 160ºC-145ºC mix-compaction temperatures to guarantee the workability of the mixes. The proportions of rubber proposed are #60-40% for mixtures with 1.5 to 2% of rubber and, #20-80% for mixture with 3% of rubber (as example, a 60% of Ø0.4-2mm and 40% of Ø2-4mm). The temperature of the asphalt cement is between 160-180 ºC for mixing and 145-160 ºC for compaction, according to the optimal values for viscosity using Brookfield viscometer and 'ring and ball' - penetration tests. These crumb rubber particles act as a rubber-aggregate into the mixture, varying sizes between 0.4mm to 2mm in a first fraction, and 2-4mm as second proportion. Ambient ground rubber with a specific gravity of 1.154g/cm³ is used. The rubber is free of loose fabric, wire, and other contaminants. It was found optimal results in real beams and cylindrical specimens with each HMA mixture reducing the swelling effect. Different factors as temperature, particle sizes of rubber, number of cycles and pressures of compaction that affect the interaction process are explained.

Keywords: crumb-rubber, gyratory compactor, rebounding effect, superpave mix-design, swelling, sub-ballast railway

Procedia PDF Downloads 243

Authors: Xiaoxiao Yu, Guodu He, Zihua Wu, Yuanyuan Wang, Huaqing Xie

Abstract:

Core-shell composite structure is a common method to regulate the spectral absorption of nanofluids, but there occur complex preparation processes, which limit the applications in some fields, such as photothermal utilization and catalysis. This work proposed point-mode Cu₂O/TiN plasmonic nanofluids to regulate the spectral capturing ability and simplify the preparation process. Non-noble TiN nanoparticles with the localized surface plasmon resonance effect are dispersed in Cu₂O nanoparticles for forming a multi-point resonance source to enhance the spectral absorption performance. The experimental results indicate that the multiple resonance effect of TiN effectively improves the optical absorption and expands the absorption region. When the radius of Cu₂O nanoparticles is equal to 150nm, the optical absorption of point-mode Cu₂O/TiN plasmonic nanoparticles is best. Moreover, the photothermal conversion efficiency of Cu₂O/TiN plasmonic nanofluid can reach 97.5% at a volume fraction of 0.015% and an optical depth of 10mm. The point-mode nanostructure effectively enhances the optical absorption properties and greatly simplifies the preparation process of the composite nanoparticles, which can promote the application of multi-component photonic nanoparticles in the field of solar energy.

Keywords: solar energy, nanofluid, point-mode structure, Cu₂O/TiN, localized surface plasmon resonance effect

Procedia PDF Downloads 61

Authors: Sonay Ödemiş

Abstract:

Movement Staff Notation System (MSNS) is a movement transcription, analyzing method, and it's been constantly improved since it was first developed in 2005. This method is based on human anatomy, is being used and applied in the lessons at The Department of Turkish Folk Dances in Istanbul Technical University, nowadays. In this research, it is aimed to discover, how MSNS can help to participants about learning the basic movements of lower extremity. This experiment has six volunteers who were randomly selected. Each volunteer has been graded for their dance backgrounds and all the volunteers have been studied for six weeks. Each week has included different topic and examples such as contacts on foot, jumps, timing, directions and basic symbols of MSNS. Examples have changed from easy to hard. On conclusion, 6 volunteer subjects were tested in final test. The tests were recorded with the camera. In this presentation, it will be explained and detailed the results of the reading test on MSNS. Some of important video records will be watched and interpreted after the test. As a conclusion, all the scores will be interpreted and assessed from different perspectives.

Keywords: dance notation, Turkish dances, reading test, Education

Procedia PDF Downloads 233

Authors: Daniel Bülz, Franziska Lüttich, Sreetama Banerjee, Georgeta Salvan, Dietrich R. T. Zahn

Abstract:

For the development of electronics, organic semiconductors are of great interest due to their adjustable optical and electrical properties. Especially for spintronic applications they are interesting because of their weak spin scattering, which leads to longer spin life times compared to inorganic semiconductors. It was shown that some organic materials change their resistance if an external magnetic field is applied. Pentacene is one of the materials which exhibit the so called photoinduced magnetoresistance which results in a modulation of photocurrent when varying the external magnetic field. Also the soluble derivate of pentacene, the 6,13-bis (triisopropylsilylethynyl)-pentacene (TIPS-pentacene) exhibits the same negative magnetoresistance. Aiming for simpler fabrication processes, in this work, we compare TIPS-pentacene organic field effect transistors (OFETs) made from solution with those fabricated by thermal evaporation. Because of the different processing, the TIPS-pentacene thin films exhibit different morphologies in terms of crystal size and homogeneity of the substrate coverage. On the other hand, the interface treatment is known to have a high influence on the threshold voltage, eliminating trap states of silicon oxide at the gate electrode and thereby changing the electrical switching response of the transistors. Therefore, we investigate the influence of interface treatment using octadecyltrichlorosilane (OTS) or using a simple cleaning procedure with acetone, ethanol, and deionized water. The transistors consist of a prestructured OFET substrates including gate, source, and drain electrodes, on top of which TIPS-pentacene dissolved in a mixture of tetralin and toluene is deposited by drop-, spray-, and spin-coating. Thereafter we keep the sample for one hour at a temperature of 60 °C. For the transistor fabrication by thermal evaporation the prestructured OFET substrates are also kept at a temperature of 60 °C during deposition with a rate of 0.3 nm/min and at a pressure below 10-6 mbar. The OFETs are characterized by means of optical microscopy in order to determine the overall quality of the sample, i.e. crystal size and coverage of the channel region. The output and transfer characteristics are measured in the dark and under illumination provided by a white light LED in the spectral range from 450 nm to 650 nm with a power density of (8±2) mW/cm2.

Keywords: organic field effect transistors, solution processed, surface treatment, TIPS-pentacene

Procedia PDF Downloads 447

Authors: Juneseok You, Kuewhan Jang, Chanho Park, Jaeyeong Choi, Hyunjun Park, Sehyun Shin, Changsoo Han, Sungsoo Na

Abstract:

Nanomaterials occur toxic effects to human being or ecological systems. Some sensors have been developed to detect toxic materials and the standard for toxic materials has been established. Zinc oxide nanowire (ZnO NW) is known for toxic material. By ionizing in cell body, ionized Zn ions are overexposed to cell components, which cause critical damage or death. In this paper, we detected ZnO NW in water using QCM (Quartz Crystal Microbalance) and ssDNA (single strand DNA). We achieved 30 minutes of response time for real time detection and 100 pg/mL of limit of detection (LOD).

Keywords: zinc oxide nanowire, QCM, ssDNA, toxic material, biosensor

Procedia PDF Downloads 428

Authors: Tae Kyu An

Abstract:

We demonstrate repurposing linear micropatterns on the CD as a master mold to fabricate TIPS-PEN microwires. From the micropatterns on CDs, we replicated polyurethane acrylate (PUA) templates which are robust and flexible until submicrometer scale patterns. Subsequently, 1.5 μm TIPS-PEN microwires separated by 1.5 μm were grown. Using crystal analysis tools with polarized optical microscopy and X-ray diffraction measurement, it was revealed that each TIPS-PEN microwires are highly crystalline and uniform compared to spin-coated films. It is attributed to the template-guided growth of TIPS-PEN crystals along the linear template, thus the OFETs comprised of TIPS-PEN microwires displayed the high field-effect mobility.

Keywords: compact disk, macro patterning, OFET, soft lithography

Procedia PDF Downloads 239

Authors: Ali Raheli, Rahim Habibifar, Behzad Mohammadi-Alasti, Mahdi Abbasgholipour

Abstract:

This paper presents vibration behavior of a FGM micro-beam and its pull-in instability under a nonlinear electrostatic pressure. An exponential function has been applied to show the continuous gradation of the properties along thickness. Nonlinear integro-differential-electro-mechanical equation based on Euler–Bernoulli beam theory has been derived. The governing equation in the static analysis has been solved using Step-by-Step Linearization Method and Finite Difference Method. Fixed points or equilibrium positions and singular points have been shown in the state control space. In order to find the response to a step DC voltage, the nonlinear equation of motion has been solved using Galerkin-based reduced-order model and time histories and phase portrait for different applied voltages have been shown. The effects of electrostatic pressure on stability of FGM micro-beams having various amounts of the ceramic constituent have been investigated.

Keywords: FGM, MEMS, nonlinear vibration, electrical, dynamic pull-in voltage

Procedia PDF Downloads 456

Authors: Yalçın Kılıç, İbrahim Kani

Abstract:

The conversion of hydrocarbons to carbonyl compounds by oxidation reaction is one of the most important reactions in the synthesis of fine chemicals. As a result of the oxidation of hydrocarbons containing aliphatic sp3-CH groups in their structures, aldehydes, ketones or carboxylic acids can be obtained. In this study, OSSO-type 2,2'-[1,4-butanedylbis(thio)]bis-benzoic acid (tsabutH2) ligand and [Zn(µ-tsabut)(phen)]n complex (where phen = 1,10-phenantroline) were synthesized and their structures were characterized by single crystal x-ray diffraction method. The catalytic efficiency of the complex in the catalytic oxidation studies of organic compounds such as cyclohexane, ethylbenzene, diphenylmethane, and p-xylene containing sp3-C-H in its structure was investigated.

Keywords: metal complex, OSSO-type ligand, catalysis, oxidation

Procedia PDF Downloads 100

Authors: J. Lyagaeva, D. Medvedev, A. Brouzgou, A. Demin, P. Tsiakaras

Abstract:

The investigation of highly conductive and chemically stable electrolytes for solid oxide fuel cells (SOFC) is a necessity. The aim of the present work is to study the influence of acceptor dopant on the functional properties of textured BaCe0.5Zr0.3Ln0.2O3−δ (Ln = Yb, Y, Gd, Sm, Nd) ceramics. The X-Ray diffraction analysis, scanning electron microscopy, dilatometry and 4-probe dc method of conductivity measurements were used. It was found that the mean grain size of ceramics increases (from 1.4 to 3.2 μm), thermal expansion coefficient grows (from 7.6•10–6 to 10.7•10–6 К–1), but ionic conductivity decreases (from 14 to 3 mS cm–1 at 900°С), when ionic radii of impurity acceptor increases from 0.868 Å (Yb3+) to 0.983 Å (Nd3+).

Keywords: acceptor dopant, crystal structure, proton-conducting, SOFC

Procedia PDF Downloads 371

Authors: J. Tomilla Ajayi, Werner E. Van Zyl

Abstract:

This work presents an overview of the reaction of 2, 4-diferrocenyl-1, 3-dithiadiphosphetane-2, 4-disulfide (Ferrocenyl Lawesson’s reagent) with water to produce the non-symmetric, ferocenyl dithiophosphonic acid respectively in high yields. These acids were readily deprotonated by anhydrous Ammonia to yield the corresponding ammonium salt NH4S2PFcOH. These were complex to Ni (II) in molar ratio 1:1 and 1:2. The resulting complex from the reaction formed same compound with different isomers (Cis and Trans) and also compound with multimetallic coordination. Quality X-ray crystals were formed from THF/Ether. The compounds were characterized by 1H, 31P NMR, and FTIR. Bulk purity were confirmed by either ESI-MS or elemental analysis and The XRD images were obtained using single crystal X-ray crystallographic studies. The electrochemical investigation of the Compounds were carried out using cyclic voltammetry.

Keywords: ferrocenyl, dithiophosphonate, isomer, coordination

Procedia PDF Downloads 248

Authors: Andrei Bejan, Luminita Marin, Dalila Belei

Abstract:

Phenothiazine with electron-rich nitrogen and sulfur heteroatoms has a high electron-donating ability which promotes a good conjugation and therefore low band-gap with consequences upon charge carrier mobility improving and shifting of light emission in visible domain. Moreover, its non-planar butterfly conformation inhibits molecular aggregation and thus preserves quite well the fluorescence quantum yield in solid state compared to solution. Therefore phenothiazine and its derivatives are promising hole transport materials for use in organic electronic and optoelectronic devices as light emitting diodes, photovoltaic cells, integrated circuit sensors or driving circuits for large area display devices. The objective of this paper was to obtain a series of new phenothiazine derivatives by introduction of different electron withdrawing substituents as formyl, carboxyl and cyanoacryl units in order to create a push pull system which has potential to improve the electronic and optical properties. Bromine atom was used as electrono-donor moiety to extend furthermore the existing conjugation. The understudy compounds were structural characterized by FTIR and 1H-NMR spectroscopy and single crystal X-ray diffraction. Besides, the single crystal X-ray diffraction brought information regarding the supramolecular architecture of the compounds. Photophysical properties were monitored by UV-vis and photoluminescence spectroscopy, while the electrochemical behavior was established by cyclic voltammetry. The absorption maxima of the studied compounds vary in a large range (322-455 nm), reflecting the different electronic delocalization degree, depending by the substituent nature. In a similar manner, the emission spectra reveal different color of emitted light, a red shift being evident for the groups with higher electron withdrawing ability. The emitted light is pure and saturated for the compounds containing strong withdrawing formyl or cyanoacryl units and reach the highest quantum yield of 71% for the compound containing bromine and cyanoacrilic units. Electrochemical study show reversible oxidative and reduction processes for all the compounds and a close correlation of the HOMO-LUMO band gap with substituent nature. All these findings suggest the obtained compounds as promising materials for optoelectronic devices.

Keywords: electrochemical properties, phenothiazine derivatives, photoluminescence, quantum yield

Procedia PDF Downloads 329

Authors: Ahteshamul Haq, Srikant Gupta, Murshid Kamal, Irfan Ali

Abstract:

This case study designs and builds a multi-objective production planning model for a hardware firm with certain & uncertain data. During the time of interaction with the manager of the firm, they indicate some of the parameters may be vague. This vagueness in the formulated model is handled by the concept of fuzzy set theory. Triangular & Trapezoidal fuzzy numbers are used to represent the uncertainty in the collected data. The fuzzy nature is de-fuzzified into the crisp form using well-known defuzzification method via graded mean integration representation method. The proposed model attempts to maximize the production of the firm, profit related to the manufactured items & minimize the carrying inventory costs in both certain & uncertain environment. The recommended optimal plan is determined via fuzzy programming approach, and the formulated models are solved by using optimizing software LINGO 16.0 for getting the optimal production plan. The proposed model yields an efficient compromise solution with the overall satisfaction of decision maker.

Keywords: production planning problem, multi-objective optimization, fuzzy programming, fuzzy sets

Procedia PDF Downloads 213

Authors: Y. Mateyshina, A.Ulihin, N.Uvarov

Abstract:

Electrolytes with different type of charge carrier can find widely application in different using, e.g. sensors, electrochemical equipments, batteries and others. One of important components ensuring stable functioning of the equipment is electrolyte. Electrolyte has to be characterized by high conductivity, thermal stability, and wide electrochemical window. In addition to many advantageous characteristic for liquid electrolytes, the solid state electrolytes have good mechanical stability, wide working range of temperature range. Thus search of new system of solid electrolytes with high conductivity is an actual task of solid state chemistry. Families of alkali perchlorates and nitrates have been investigated by us earlier. In literature data about transport properties of alkali nitrites are absent. Nevertheless, alkali nitrites MeNO2 (Me= Li+, Na+, K+, Rb+ and Cs+), except for the lithium salt, have high-temperature phases with crystal structure of the NaCl-type. High-temperature phases of nitrites are orientationally disordered, i.e. non-spherical anions are reoriented over several equivalents directions in the crystal lattice. Pure lithium nitrite LiNO2 is characterized by ionic conductivity near 10-4 S/cm at 180°C and more stable as compared with lithium nitrate and can be used as a component for synthesis of composite electrolytes. In this work composite solid electrolytes in the binary system LiNO2 - A (A= MgO, -Al2O3, Fe2O3, CeO2, SnO2, SiO2) were synthesized and their structural, thermodynamic and electrical properties investigated. Alkali nitrite was obtained by exchange reaction from water solutions of barium nitrite and alkali sulfate. The synthesized salt was characterized by X-ray powder diffraction technique using D8 Advance X-Ray Diffractometer with Cu K radiation. Using thermal analysis, the temperatures of dehydration and thermal decomposition of salt were determined.. The conductivity was measured using a two electrode scheme in a forevacuum (6.7 Pa) with an HP 4284A (Precision LCR meter) in a frequency range 20 Hz < ν < 1 MHz. Solid composite electrolytes LiNO2 - A A (A= MgO, -Al2O3, Fe2O3, CeO2, SnO2, SiO2) have been synthesized by mixing of preliminary dehydrated components followed by sintering at 250°C. In the series of nitrite of alkaline metals Li+-Cs+, the conductivity varies not monotonically with increasing radius of cation. The minimum conductivity is observed for KNO2; however, with further increase in the radius of cation in the series, the conductivity tends to increase. The work was supported by the Russian Foundation for Basic research, grant #14-03-31442.

Keywords: conductivity, alkali nitrites, composite electrolytes, transport properties

Procedia PDF Downloads 319

Authors: V. Sivasubramanian, M. Jerold

Abstract:

The advancement of adsorption is the development of nano-biocomposite for the sorption dyes and heavy metal ions. In fact, Nanoscale zerovalent iron (NZVI) is cost-effective reducing agent and a most reliable biosorbent for the dye biosorption. In this study, nano zero valent iron Sargassum swartzii (nZVI-SS) biocomposite, a novel marine algal based biosorbent, was used for the removal of simulated crystal violet (CV) in batch mode of operation. The Box-Behnen design (BBD) experimental results revealed the biosoprtion was maximum at pH 7.5, biosorbent dosage 0.1 g/L and initial CV concentration of 100 mg/L. Therefore, the result implies that nZVI-SS biocomposite is a cheap and most promising biosorbent for the removal of CV from wastewater.

Keywords: algae, biosorption, zero-valent, dye, waste water

Procedia PDF Downloads 248

Authors: Zekun Lin, Xun Li

Abstract:

Silicon photonics has gained much interest and extensive research for a promising aspect for fabricating compact, high-speed and low-cost photonic devices compatible with complementary metal-oxide-semiconductor (CMOS) process. Despite the remarkable progress made on the development of silicon photonics, high-performance, cost-effective, and reliable silicon laser sources are still missing. In this work, we present a 1550 nm III-V/silicon laser design with stable single-mode lasing property and robust and high-efficiency vertical coupling. The InP cavity consists of two uniform Bragg grating sections at sides for mode selection and feedback, as well as a central second-order grating for surface emission. A grating coupler is etched on the SOI waveguide by which the light coupling between the parallel III-V and SOI is reached vertically rather than by evanescent wave coupling. Laser characteristic is simulated and optimized by the traveling-wave model (TWM) and a Green’s function analysis as well as a 2D finite difference time domain (FDTD) method for the coupling process. The simulation results show that single-mode lasing with SMSR better than 48dB is achievable, and the threshold current is less than 15mA with a slope efficiency of around 0.13W/A. The coupling efficiency is larger than 42% and possesses a high tolerance with less than 10% reduction for 10 um horizontal or 15 um vertical dislocation. The design can be realized by standard flip-chip bonding techniques without co-fabrication of III-V and silicon or precise alignment.

Keywords: III-V/silicon integration, silicon photonics, single mode laser, vertical coupling

Procedia PDF Downloads 156

Authors: G. P. Abdel Rahim, M. María Guadalupe Moreno Armenta, Jairo Arbey Rodriguez

Abstract:

We investigated the structure and electronic properties of the compound Mg1-xBixO with varying concentrations of 0, ¼, ½, and ¾ x bismuth in the the NaCl (rock-salt) and WZ (wurtzite) phases. The calculations were performed using the first-principles pseudo-potential method within the framework of spin density functional theory (DFT). Our calculations predict that for Bi concentrations greater than ~70%, the WZ structure is more favorable than the NaCl one and that for x = 0 (pure MgO), x = 0.25 and x = 0.50 of Bi concentration the NaCl structure is more favorable than the WZ one. For x = 0.75 of Bi, a transition from wurtzite towards NaCl is possible, when the pressure is about 22 GPa. Also It has been observed the crystal lattice constant closely follows Vegard’s law, that the bulk modulus and the cohesion energy decrease with the concentration x of Bi.

Keywords: DFT, Mg1-xBixO, pseudo-potential, rock-salt, wurtzite

Procedia PDF Downloads 525

Authors: Merve Küçük, M. Lütfi Öveçoğlu

Abstract:

Zinc oxide particles were synthesized using the sol-gel method and dip coated on polyester fabric. X-ray diffraction (XRD) analysis revealed a single crystal phase of ZnO particles. Chemical characteristics of the polyester fabric surface were investigated using attenuated total reflection-Fourier transform infrared (ATR-FTIR) measurements. Morphology of ZnO coated fabric was analyzed using field emission scanning electron microscopy (FESEM). After particle analysis, the aqueous ZnO solution resulted in a narrow size distribution at submicron levels. The deposit of ZnO on polyester fabrics yielded a homogeneous spread of spherical particles. Energy dispersive X-ray spectroscopy (EDX) results also affirmed the presence of ZnO particles on the polyester fabrics.

Keywords: dip coating, polyester fabrics, sol gel, zinc oxide

Procedia PDF Downloads 434

Authors: Narayan Bhattarai, Arjun Bhattarai, Kabi Raj Paudyal, Lalu Paudel

Abstract:

Palung granite is leucocratic, alkali feldspar granite, which is one of the six major granite bodies of the Lesser Himalaya of Nepal. The Cambro-Ordovician granite body has intruded on the Palaeozoic metasedimentary rock of the Kathmandu Complex in Central Nepal. The granite crystallized from magma that was mainly generated by anatexis of the Precambrian continental crust. The magma is heterogeneous with respect to the primary ages and/or metamorphic histories of the magma source rocks. This indicates either a derivation from (meta-) sediments or an intense mixing of different crustally derived magmas. The genesis of the Palung granite is possibly related to an orogeny which affected the Indian shield in lower Paleozoic times. The granite body has been mapped into different zones with visual inspection and petrographical study: i. Quartz rich granite: Quartz is smokey to grayish, euhedral to subherdal, 0.2 to 0.7 cm, and constitutes 30 to 40%. Feldspar is white to brownish, subhedral to euhedral, more than 3 cm, and constitutes 20–30%. Tourmaline is black, 0.1 to 0.2 cm in size, and consists of 10 to 20%. Biotite is black flakes up to o.2 cm, representing 5-8%. ii. Feldspar rich granite: white to grayish, medium to coarse-grained, containing feldspar, quartz, biotite, muscovite and tourmaline. Feldspar porphyritic crystals up to 2.5 cm subherdral represent 50–60%, quartz is smokey transparent and represents 30–40%, biotite is dark brown to black, crystals are irregular, 0.5 cm and represent 8–20%, tourmaline is black fractured, small needles represent 5–10%, and muscovite is white to brown and represents 1-4%. iii. Biotite granite: grey to white, medium to coarse-grained, containing quartz, feldspar, biotite and tourmaline. Feldspar crystals up to 2.5 cm represent 40–50%, quartz is smokey, representing 30–40%, biotite is dark brown to black, crystal size 0.5cm, representing 10–20%, tourmaline is black, small needle, 5–10%, and muscovite is white to brown, representing 3-5%. and iv. Muscovite granite: medium-coarse-grained, brown and gray, containing quartz, feldspar, muscovite and tourmaline. Feldspar is white to brown; crystal sizes 0.2–0.4 cm represents 40–50%; quartz is brown and white, transparent, crystals up to 1 cm represent 35–50%; tourmaline is black, opaque, needle shaped; size up to 7–20%; and muscovite is brownish to white, with flakes up to 0.3 cm representing 5–10%. The xenoliths are very common and are not genetically related. Xenoliths are composed mostly of fine-grained, grayish quartz biotite (muscovite) schist and garnetiferous quartz mica schist.

Keywords: leucocratic granite, cambro-ordovician granite, lesser himalayan granite, pegmatite

Procedia PDF Downloads 71

Authors: F. Hadjaj, A. Belghachi, A. Halmaoui, M. Belhadj, H. Mazouz

Abstract:

A laser is essentially an optical oscillator consisting of a resonant cavity, an amplifying medium and a pumping source. In semiconductor diode lasers, the cavity is created by the boundary between the cleaved face of the semiconductor crystal and air and also has reflective properties as a result of the differing refractive indices of the two media. For a GaAs-air interface a reflectance of 0.3 is typical and therefore the length of the semiconductor junction forms the resonant cavity. To prevent light, being emitted in unwanted directions from the junction and Sides perpendicular to the required direction are roughened. The objective of this work is to simulate the optical resonator Fabry-Perot and explore its main characteristics, such as FSR, Finesse, Linewidth, Transmission and so on that describe the performance of resonator.

Keywords: Fabry-Perot Resonator, laser diod, reflectance, semiconductor

Procedia PDF Downloads 352

Authors: Shin Yoneda, Mikiya Kato, Kosuke Murate, Kodo Kawase

Abstract:

In recent years, there have been numerous attempts to smuggle narcotic drugs and chemicals by concealing them in international mail. Combatting this requires a non-destructive technique that can identify such illicit substances in mail. Terahertz (THz) waves can pass through a wide variety of materials, and many chemicals show specific frequency-dependent absorption, known as a spectral fingerprint, in the THz range. Therefore, it is reasonable to investigate non-destructive mail inspection techniques that use THz waves. For this reason, in this work, we tried to identify reagents under high attenuation shielding materials using injection-seeded THz-wave parametric generator (is-TPG). Our THz spectroscopic imaging system using is-TPG consisted of two non-linear crystals for emission and detection of THz waves. A micro-chip Nd:YAG laser and a continuous wave tunable external cavity diode laser were used as the pump and seed source, respectively. The pump beam and seed beam were injected to the LiNbO₃ crystal satisfying the noncollinear phase matching condition in order to generate high power THz-wave. The emitted THz wave was irradiated to the sample which was raster scanned by the x-z stage while changing the frequencies, and we obtained multispectral images. Then the transmitted THz wave was focused onto another crystal for detection and up-converted to the near infrared detection beam based on nonlinear optical parametric effects, wherein the detection beam intensity was measured using an infrared pyroelectric detector. It was difficult to identify reagents in a cardboard box because of high noise levels. In this work, we introduce improvements for noise reduction and image clarification, and the intensity of the near infrared detection beam was converted correctly to the intensity of the THz wave. A Gaussian spatial filter is also introduced for a clearer THz image. Through these improvements, we succeeded in identification of reagents hidden in a 42-mm thick cardboard box filled with several obstacles, which attenuate 56 dB at 1.3 THz, by improving analysis methods. Using this system, THz spectroscopic imaging was possible for saccharides and may also be applied to cases where illicit drugs are hidden in the box, and multiple reagents are mixed together. Moreover, THz spectroscopic imaging can be achieved through even thicker obstacles by introducing an NIR detector with higher sensitivity.

Keywords: nondestructive inspection, principal component analysis, terahertz parametric source, THz spectroscopic imaging

Procedia PDF Downloads 177

Authors: K. V. Ramanaiah, R. Jagan, N. N. Murthy

Abstract:

Trinuclear oxo-centered carboxylate-bridged iron complexes, [Fe3(µ3-O)(µ2-O2CR)L¬3]+/0 (where R = alkyl or aryl; L = H2O, ROH, Py, solvent) have attracted tremendous attention because of their interesting structural and magnetic properties, exhibit mixed-valent trapped and de-trapped states, and have bioinorganic relevance. The presence of a trinuclear iron binding center has been implicated in the formation of both bacterial and human iron storage protein, Ft. They are used as precursors for the synthesis of models for the active-site structures of non-heme proteins, hemerythrin (Hr), methane monooxygenase (MMO) and polyiron storage protein, ferritin (Ft). Used as important building blocks for the design and synthesis of supramolecules this can exhibit single molecular magnetism (SMM). Such studies have often employed simple and compact carboxylate ligands and the use of bulky carboxylates is scarce. In the present study, we employed two different type of sterically hindered carboxylates and synthesized a series of novel oxo-centered, carboxylate-bridged triiron complexes of general formula [Fe3(O)(O2CCPh3)6L3]X (L = H2O, 1; py, 2; 4-NMe2py, 3; X = ClO4; L = CH3CN, 4; X = FeCl4) and [Fe3(O)(O2C-anth)6L3]X (L = H2O, 5; X = ClO4; L = CH3OH, 6; X = Cl). Along with complex [Fe(OMe)2(O2CCPh3)]10, 7 was prepared by the self-assemble of anhydrous FeCl3, sodium triphenylacetate and sodium methoxide at ratio of 1:1:2 in CH3OH. The Electronic absorption spectra of these complexes 1-6, in CH2Cl2 display weak bands at near FTIR region (970-1135 nm, ε > 15M-1cm-1). For complex 7, one broad band centered at ~670nm and also an additional intense charge transfer (L→M or O→M) bands between 300 to 550nm observed for all the complexes. Paramagnetic 1H NMR is introduced as a good probe for the characterization of trinuclear oxo - cantered iron compounds in solution when the L ligand coordinated to iron varies as: H2O, py, 4-NMe2py, and CH3OH. The solution state magnetic moment values calculated by using Evans method for all the complexes and also solid state magnetic moment value of complex, 7 was calculated by VSM method, which is comparable with solution state value. These all magnetic moment values indicate there is a spin exchange process through oxo and carboxylate bridges in between two irons (d5). The ESI-mass data complement the data obtained from single crystal X-ray structure. Further purity of the compounds was confirmed by elemental analysis. Finally, structural determination of complexes 1, 3, 4, 5, 6 and 7 were unambiguously conformed by single crystal x-ray studies.

Keywords: decanuclear, paramagnetic NMR, trinuclear, uv-visible

Procedia PDF Downloads 348

Authors: Tahsien Mohamed Okasha

Abstract:

Simulation is one of the emerging educational strategies that depend on the creation of scenarios to imitate what could happen in real life. At the time of COVID, we faced big obstacles in medical education, specially the clinical part and how we could apply it, the simulation was the golden key. Simulation is a very important tool of education for medical sector students, through creating a safe, changeable, quiet environment with less anxiety level for students to practice and to have repeated trials on their competencies. That impacts the level of practice, achievement, and the way of acting in real situations and experiences. A blind Random sample of students from different specialties and colleges who came and finished their training in an integrated environment was collected and tested, and the responses were graded from (1-5). The results revealed that 77% of the studied subjects agreed that dealing and interacting with different medical sector candidates in the same place was beneficial. 77% of the studied subjects agreed that simulations were challenging in thinking and decision-making skills .75% agreed that using high-fidelity manikins was helpful. 75% agree .76% agreed that working in a safe, prepared environment is helpful for realistic situations.

Keywords: simulation, clinical training, education, medical sector students

Procedia PDF Downloads 31