Open Access. Powered by Scholars. Published by Universities.®

Biotechnology Commons™

Open Access. Powered by Scholars. Published by Universities.®

Discipline
Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 1861 - 1890 of 3194

Full-Text Articles in Biotechnology

Survivability In Metro Ring Network Using Oxadm, Ab-Rahman Mohammad Syuhaimi, Shaari Sahbudin Nov 2017

Survivability In Metro Ring Network Using Oxadm, Ab-Rahman Mohammad Syuhaimi, Shaari Sahbudin

ASEAN Journal on Science and Technology for Development

The optical cross add and drop multiplexing (OXADM) node described in this paper increases the capacity, flexibility and reliability of the trunk-line optical network used for data communication. It features two different bandwidths which operate in working and protection line in a ring configuration. The OXADM has the same features of the conventional OADM node but with more efficiency and reliability. The OXADM prototype system focuses on providing survivability through restoration against failures, such as cable/fiber cut in optical layer with ring topology. Two types of restoration scheme have been proposed to ensure data flow continuously by means of linear/ …

Go to article

Nonlinear Finite Element Analysis Of Nonseismically Detailed Interior Rc Beam-Column Connection Under Reversed Cyclic Load, Supaviriyakit Teeraphot, Pimanmas Amorn, Warnitchai Pennung Nov 2017

Nonlinear Finite Element Analysis Of Nonseismically Detailed Interior Rc Beam-Column Connection Under Reversed Cyclic Load, Supaviriyakit Teeraphot, Pimanmas Amorn, Warnitchai Pennung

ASEAN Journal on Science and Technology for Development

This paper presents a nonlinear finite element analysis of non-seismically detailed RC beam column connections under reversed cyclic load. The test of half-scale nonductile reinforced concrete beam-column joints was conducted. The tested specimens represented those of the actual mid-rise reinforced concrete frame buildings designed according to the non-seismic provisions of the ACI building code. The test results show that specimens representing small and medium column tributary area failed in brittle joint shear while specimen representing large column tributary area failed by ductile flexure though no ductile reinforcement details were provided. The nonlinear finite element analysis was applied to simulate the …

Go to article

Flexural Stress Analysis Of Rigid Pavements Using Axi-Symmetric And Plane Strain Fem, Sawant V.A., Norazzlina M.S. Nov 2017

Flexural Stress Analysis Of Rigid Pavements Using Axi-Symmetric And Plane Strain Fem, Sawant V.A., Norazzlina M.S.

ASEAN Journal on Science and Technology for Development

The design of pavement involves a study of soils and paving materials, their response under load for different climatic conditions. In the present study, an attempt has been made to compare stresses predicted using two finite element analyses. First analysis is based on the twodimensional plane strain assumption where as in second approach axi-symmetric condition is assumed to consider three-dimensional behavior of rigid pavement. The results are compared with flexural stresses obtained from conventional Portland Cement Association method. The computed flexural stresses obtained from axi-symmetric condition are found to be in close agreement with PCA method. Results of plane strain …

Go to article

New Upper And Lower Bounds Line Of Sight Path Loss Models For Mobile Propagation In Buildings, Phaiboon Supachai, Phokharatkul P., Somkuarnpanit Suripon Nov 2017

New Upper And Lower Bounds Line Of Sight Path Loss Models For Mobile Propagation In Buildings, Phaiboon Supachai, Phokharatkul P., Somkuarnpanit Suripon

ASEAN Journal on Science and Technology for Development

This paper proposes a method to predict line-of-sight (LOS) path loss in buildings. We performed measurements in two different type of buildings at a frequency of 1.8 GHz and propose new upper and lower bounds path loss models which depend on max and min values of sample path loss data. This makes our models limit path loss within the boundary lines. The models include time-variant effects such as people moving and cars in parking areas with their influence on wave propagation that is very high. The results have shown that the proposed models will be useful for the system and …

Go to article

Electroresponsie Behavior Of Polyelectrolyte Gels (Acrylic Acid-Co-N-N' Methylene Bisacrylamide) Under The Influence Of Electric Field, Nam Nguyen Phuong Hoai, Mendes Eduado Nov 2017

Electroresponsie Behavior Of Polyelectrolyte Gels (Acrylic Acid-Co-N-N' Methylene Bisacrylamide) Under The Influence Of Electric Field, Nam Nguyen Phuong Hoai, Mendes Eduado

ASEAN Journal on Science and Technology for Development

Polymer gels which were synthesized from acrylic acid and N-N’ methylene bisacrylamide exhibited electrical sensitive behavior. Their swelling properties and electroresponsive behavior were studied. The results indicated that the water take-up ability of the hydrogel increased with the decreased N-N’ methylene bisacrylamide content within the network. The hydrogel membranes swollen in a neutral NaCl solution, bent toward the cathode under non-contact DC electric fields, and their bending speed and equilibrium strain increased with the increased of applied voltage. In addition, the effect of crosslinker concentration of N-N’ methylene bisacrylamide on bending behavior of the gels have been studied. The equilibrium …

Go to article

An Approach Designing Autonomous Robot Navigation System Based On Behavior Coordination, Ngo Long Thanh, Pham Long The, Nguyen Phuong Hoang Nov 2017

An Approach Designing Autonomous Robot Navigation System Based On Behavior Coordination, Ngo Long Thanh, Pham Long The, Nguyen Phuong Hoang

ASEAN Journal on Science and Technology for Development

Robot navigation using fuzzy behavior is suited in unknown and unstructured environment in which each behavior have an individual task. This paper deals with an approach designing autonomous robot navigation system based on fuzzy behaviors including collision avoidance, wall-following, go-to-target. The proposed hierarchy of fuzzy behaviors is used to fuse the command in which each behavior is a fuzzy inference system and its outputs are fuzzy sets. Its inputs are information fused from sensors using fuzzy directional relationship. The simulation results with some statistics show that the system works correctly.

Go to article

Simulated-Data Adaptation Based Piecewise Linear Transformation For Robust Speech Recognition, Thatphithakkul Nattanun, Kruatrachue Boontee, Wutiwiwatchai Chai, Marukatat Sanparith, Boonpiam Vataya Nov 2017

Simulated-Data Adaptation Based Piecewise Linear Transformation For Robust Speech Recognition, Thatphithakkul Nattanun, Kruatrachue Boontee, Wutiwiwatchai Chai, Marukatat Sanparith, Boonpiam Vataya

ASEAN Journal on Science and Technology for Development

This paper proposes an efficient method of simulated-data adaptation for robust speech recognition. The method is applied to tree-structured piecewise linear transformation (PLT). The original PLT selects an acoustic model using tree-structured HMMs and the acoustic model is adapted by input speech in an unsupervised scheme. This adaptation can degrade the acoustic model if the input speech is incorrectly transcribed during the adaptation process. Moreover, adaptation may not be effective if only the input speech is used. Our proposed method increases the size of adaptation data by adding noise portions from the input speech to a set of prerecorded clean …

Go to article

Optical Studies Of Penicillin Group In Relation To Their Medical Activity, Kumar R. Jeevan, Prasad G.V.R., Shoaib S.Md., Devadanam G. Paul, Fakruddin K. Nov 2017

Optical Studies Of Penicillin Group In Relation To Their Medical Activity, Kumar R. Jeevan, Prasad G.V.R., Shoaib S.Md., Devadanam G. Paul, Fakruddin K.

ASEAN Journal on Science and Technology for Development

The study of Medical activity of antibiotics is gaining momentum now a days owing to the importance of their curative values. The Medical Activity correlated to molecular interactions,can be studied by various physical techniques, at present optical methods like Refractometry and Polarization are used to study the activity of a few antibiotics like Penicillin. The Refractive Indices Mean Molecular Polarizability Diamagnetic Susceptibilities and Electron Ionisation Cross Section are interpreted in terms of dosages and the toxic effects if any due to over dosages are discussed critically.

Go to article

Design And Implementation Of A Vhdl Processor For Dct Based Image Compression, Islam Md. Shabiul, Bhuyan M.S., Beg M. Salim, Othman Masuri Nov 2017

Design And Implementation Of A Vhdl Processor For Dct Based Image Compression, Islam Md. Shabiul, Bhuyan M.S., Beg M. Salim, Othman Masuri

ASEAN Journal on Science and Technology for Development

This paper describes the design and implementation of a VHDL processor meant for performing 2D-Discrete Cosine Transform (DCT) to use in image compression applications. The design flow starts from the system specification to implementation on silicon and the entire process is carried out using an advanced workstation based design environment for digital signal processing. The software allows the bit-true analysis to ensure that the designed VLSI processor satisfies the required specifications. The bit-true analysis is performed on all levels of abstraction (behavior, VHDL etc.). The motivation behind the work is smaller size chip area, faster processing, reducing the cost of …

Go to article

A Review On Energy Efficiency Standards And Labels: Present Status And Implementation Possibilities In Malaysia, Mahlia, T.M.I., Masjuki, H.H., Choudhury I.A., R. Saidur And R. Saidur Nov 2017

A Review On Energy Efficiency Standards And Labels: Present Status And Implementation Possibilities In Malaysia, Mahlia, T.M.I., Masjuki, H.H., Choudhury I.A., R. Saidur And R. Saidur

ASEAN Journal on Science and Technology for Development

This article is a review on energy efficiency standards and labels for household electrical appliances around the world. Through the review of other country experiences on energy efficiency standards and labels, we attempt to identify savings possibilities in Malaysian households. The implementation possibilities of standards and labels for various household electrical appliances in Malaysia are also examined. It is found that various household appliances in Malaysia offer some potential in reducing electricity consumption. Finally, it is concluded that there are many advantages for Malaysia to implement the standards and labels for household electrical appliances as soon as possible in order …

Go to article

Co Cluster Formation In Tio2 Dms And A Method Of Estimation, Hong Le Van, Thuan Nguyen Chi, Dai Nguyen Van, Phuc Nguyen Xuan Nov 2017

Co Cluster Formation In Tio2 Dms And A Method Of Estimation, Hong Le Van, Thuan Nguyen Chi, Dai Nguyen Van, Phuc Nguyen Xuan

ASEAN Journal on Science and Technology for Development

The paper presents experimental observations of the Co cluster formation in TiO2/Co powder samples prepared by the Sol-Gel method. The obtained X-ray diffraction patterns and Raman scattering show that the anatase phase of TiO2 was successfully synthesized at an annealing temperature of 450°C. Comprehensive studies by means of X-ray diffraction, Raman scattering, thermal magnetization in a temperature range of 300–1000 K and magnetic hysteresis at room temperature confirm that a part of Co did not substitute for Ti in TiO2 structure, otherwise it has reasonably formed cluster of Co in samples. Based on the thermal magnetization curves a method to …

Go to article

Peculiar Optical Properties Of Co2mnga Alloys, Rhee Joo Yull, Kudryavtsev Y.V., Kim K.W., Lee Y.P. Nov 2017

Peculiar Optical Properties Of Co2mnga Alloys, Rhee Joo Yull, Kudryavtsev Y.V., Kim K.W., Lee Y.P.

ASEAN Journal on Science and Technology for Development

Co2MnGa alloy was prepared by the conventional arc-melting method. The optical conductivity (OC) spectrum of the alloy was measured by a rotating-analyzer spectroscopic ellipsometer. The OC spectrum was also calculated based on the electronic structure by using the full-potential linearized-augmented-plane-wave method within the local-spin-density approximation to the density-functional theory. The calculated OC spectrum does not agree well with the experimental one. Since the Co2MnGa alloy could be a strongly-correlated material, the so-called 'LDA+U' method was applied with U = 5.4 eV. The calculated OC spectrum using the 'LDA+U' method agrees very well with the experimental one. The inclusion of the …

Go to article

Optical And Structural Properties Of Optical Thin Films With Various Columnar Microstructures, Woo Seouk-Hoon, Park Yong Jun, Hwangbo Chang Kwon Nov 2017

Optical And Structural Properties Of Optical Thin Films With Various Columnar Microstructures, Woo Seouk-Hoon, Park Yong Jun, Hwangbo Chang Kwon

ASEAN Journal on Science and Technology for Development

In this study, optical and structural properties of the thin films prepared using glancing angle deposition (GLAD) are investigated. Various glancing angles and substrate rotations are employed to control the columnar microstructure of the films. The results show that as the glancing angle increases, the column angle and the porosity of TiO2 films increase and the refractive index decreases, due to shadow effects. The optical anisotropy of tilted and zigzag microstructure TiO2 films have a large anisotropy and reaches a maximum at a glancing angle of 60°, while that of helical microstructure TiO2 film deposited at 60° with substrate rotation …

Go to article

Europium Silicate Thin Films Fabricated By Rf Magnetron Sputtering And Thermal Treatment, Shin Young Chul, Kim Eun Hong, Kim Tae Geun Nov 2017

Europium Silicate Thin Films Fabricated By Rf Magnetron Sputtering And Thermal Treatment, Shin Young Chul, Kim Eun Hong, Kim Tae Geun

ASEAN Journal on Science and Technology for Development

We report the fabrication and optical characteristics of europium silicate thin films. Layer structures of Eu2O3/SiOX/Si (100) were deposited by an rf-sputtering method and annealed at 1100°C by rapid thermal annealing (RTA). Two methods were used for the deposition of SiOX layer: One was deposited by sputtering using SiO2 target (Ar gas at a rate of 50 sccm) and the other was deposited by reactive sputtering using Si target (Ar gas at a rate of 45 sccm, with an O2 gas at a rate of 5 sccm). Photoluminescence peak at 430 nm was observed in the sample composed of SiOx …

Go to article

Research And Development Of Diode-Pumped Passively Q-Switched Nd:Yvo4 Lasers Using Cr4+:Yag Crystal As Saturable Absorber, Nghia Nguyen Trong, Huy Trinh Dinh, Nga Le Thi Thanh, Hung Nguyen Dai Nov 2017

Research And Development Of Diode-Pumped Passively Q-Switched Nd:Yvo4 Lasers Using Cr4+:Yag Crystal As Saturable Absorber, Nghia Nguyen Trong, Huy Trinh Dinh, Nga Le Thi Thanh, Hung Nguyen Dai

ASEAN Journal on Science and Technology for Development

The results in research and development of diode-pumped passively Q-switched Nd:YVO4 lasers are presented with Cr4+:YAG crystal used as an intra-cavity saturable absorber. Using a-cut Nd:YVO4 laser crystals, the passively Q-switched lasers have been successfully developed and provided stable single shortest pulses of 40 ns at the repetition rate of 18.5 kHz, the maximal average output power of 180 mW was achieved corresponding to the optical efficiency of 9% and the slope efficiency of 16%. The dependences of average output power, repetition rate, pulse width and peak power on pump diode power for different transmissions of output mirror are also …

Go to article

Preparation Of The Single Mode Planar Optical Splitter Modules And Their Characterizations, Mien Vu Doan, Nghiem Vu Thi, Truong Pham Van Nov 2017

Preparation Of The Single Mode Planar Optical Splitter Modules And Their Characterizations, Mien Vu Doan, Nghiem Vu Thi, Truong Pham Van

ASEAN Journal on Science and Technology for Development

Optical splitter modules have been prepared based on 1x8 single mode silica planar waveguide optical splitter chips with 250 µm spacing and v-groove fiber arrays for applications in fiber optic communications. We report the technology of precise optical coupling and packaging of the splitter modules and the measurements of the insertion loss (< 11 dB), uniformity (< 0.80 dB) and polarization dependence loss (PLD < 0.10 dB) as well as the lateral profile and the image of the input and output lights for the wavelengths of 1310 nm and 1550 nm. The main characteristics of the prepared splitter modules are about the same for the commercial available products. The prepared modules have been tested for operation in the conditions of wide temperature range (5–80°C) and humidity range (50–98%) and no changes in the main characteristics were observed.

Go to article

Cvd Prepared Mn-Doped Zno Nanowires, Phan T.L., Vincent R., Cherns D., Nghia N.X. Nov 2017

Cvd Prepared Mn-Doped Zno Nanowires, Phan T.L., Vincent R., Cherns D., Nghia N.X.

ASEAN Journal on Science and Technology for Development

Mn-doped ZnO nanowires prepared by chemical vapor deposition (CVD) were obtained in the temperature range of 450–500°C. X-ray diffraction patterns, SEM and TEM images indicate that crystals with a hexagonal structure grow along the c axis. At low Mn-doped concentrations, photoluminescence (PL) and Raman scattering (RS) spectra are almost independent of the Mn doping. However, the increase in concentration of Mn above 1.6 at% weakens significantly the PL signal and the RS-lines intensity in the low wavenumber range of 300–480 cm-1, and concurrently increases the RS-lines intensity in the higher wavenumber range of 480-700 cm-1.. Magnetic measurements determined the Curie …

Go to article

Duration Limit Of Laser Pulses Emitted From A Ce-Doped Crystal Short Cavity, Hai Le Hoang, Hung Nguyen Dai, Hoa Hoang Huu, Quema Alex V. V., Sarukura Nobuhiko Nov 2017

Duration Limit Of Laser Pulses Emitted From A Ce-Doped Crystal Short Cavity, Hai Le Hoang, Hung Nguyen Dai, Hoa Hoang Huu, Quema Alex V. V., Sarukura Nobuhiko

ASEAN Journal on Science and Technology for Development

Based on the rate equation set for broadband cavities, the dependence of pulse duration on cavity and pumping parameters is analyzed. The cavity uses a Ce-doped crystal as a gain medium. Computation results show the variation of the pulse width with the change of cavity length, mirror reflectivity, pumping energy and pumping pulse duration. A significant influence of multiple-pulse operation in limiting pulse duration is realized and a pulse-width of the order 200 ps is found to be the limit for the direct generation of ultraviolet single picosecond pulses from a Ce:LLF short cavity.

Go to article

Investigation Of Zno Nano Structures Fabricated On Al2o3 Substractes By Mocvd, Binh Nguyen Thanh, Bich Vu Thi, Segawa Y. Nov 2017

Investigation Of Zno Nano Structures Fabricated On Al2o3 Substractes By Mocvd, Binh Nguyen Thanh, Bich Vu Thi, Segawa Y.

ASEAN Journal on Science and Technology for Development

High quality ZnO nanostructures were grown directly on sapphire subtracts by metal organic vapor deposition. By changing the growth conditions, the different nano structures (nanorods,nanotubes, nanowalls, nanonetworks) can be selectively. These nanostructures were all epitaxially grown and had the same epitaxial relationship with respect to the substrate. Mechanisms corresponding to different nanostructures were discussed. The nanostructures exhibited stable excitonic states at room temperature, and the emission due to exciton-exciton scattering was observed

Go to article

Fermentation Of Oil Palm Trunk Acid Hydrolysate To Ethanol, Yeoh H. H., Lim K. O., Mashitah M. D. Nov 2017

Fermentation Of Oil Palm Trunk Acid Hydrolysate To Ethanol, Yeoh H. H., Lim K. O., Mashitah M. D.

ASEAN Journal on Science and Technology for Development

Studies on the feasibility of using oil palm trunk acid hyd10lysates as a substrate for ethanol p10duction using the yeast Saccha10myces cerevisiae were carried out in shake flask culture. The effect of pH and fermentation time on the rate of ethanol p10duction were investigated. Results showed that with 3 hours fermentation period, the highest ethanol yield was obtained at pH 4.75. This yield was about 14% of the dry weight of the sample used; thus giving a fermentation efficiency of 94.7%.

Go to article

Spectrophotometric Method For Hg(Ii) Determination In Aqueous Environment Using Zinc-Dithizonate Complex, Ahmad, Musa Ahmad, Marsom Elya Sufliza, Hamzah Harun Nov 2017

Spectrophotometric Method For Hg(Ii) Determination In Aqueous Environment Using Zinc-Dithizonate Complex, Ahmad, Musa Ahmad, Marsom Elya Sufliza, Hamzah Harun

ASEAN Journal on Science and Technology for Development

This article described the use of zinc-dithizonate for spectrophotometric determination of Hg(II) in aqueous environment. Zinc dithizonate was found to react selectively with Hg(II) to give a reddish yellow complex with optimum absorbance at pH 1.0. This complex was found to be useful for spectrophotometric determination of aqueous Hg(II) in the concentration range of 1.0 - 12.0 ppm. This method was also found to be reproducible with calculated relative standard deviation, RSD of 1.08%. At 1:1 mole ratio, interfering ions such as CH COO·, Pb2+ and Ag+ were found to interfere at degree 3 of interference of more than 10.0%.

Go to article

Concentrations Of Lead (Pb) In Road Dust In Bandar Seri Begawan, Brunei Darussalam, Emran, Shahrizal, Fernando, K. Rodney, Radojevic And Miroslav Radojevic Nov 2017

Concentrations Of Lead (Pb) In Road Dust In Bandar Seri Begawan, Brunei Darussalam, Emran, Shahrizal, Fernando, K. Rodney, Radojevic And Miroslav Radojevic

ASEAN Journal on Science and Technology for Development

A first-ever survey oflead (Pb) in road dust in Bandar Seri Begawan (B.S.B.), the capital of Brunei Darussalam, was carried out in 1996, three years after the introduction of unleaded petrol. The concentration of Pb at 114 sites varied between 12 and 544 µg/g (mean: 125 µg/g; standard deviation: 103 µg/g). There was a significant correlation (r=0.546) between lead in road dust and traffic volume at 17 sites for which traffic counts were available. An assessment of the potential hazard posed to children was made. It is concluded that concentration levels of Pb in road dust in B.S.B. are considerably …

Go to article

Study On The Osmotic Pre-Treatment And Infrared Radiation On Drying Kinetics And Colour Changes During Drying Of Agricultural Products, Chou, S. K., Chua, K. J., Mujumdar A. S., Tan And, M., Tan S. L. Nov 2017

Study On The Osmotic Pre-Treatment And Infrared Radiation On Drying Kinetics And Colour Changes During Drying Of Agricultural Products, Chou, S. K., Chua, K. J., Mujumdar A. S., Tan And, M., Tan S. L.

ASEAN Journal on Science and Technology for Development

A combination of intermittent infrared and continuous convection heating was used to dehydrate various osmotically pretreated sample of potato (in solutions of 10%, 20% and 30% NaCl) and pineapple (in solutions of 30%, 50%, 70% Brix). In one set of runs, the infrared source was turned on and off sequentially according to a predetermined time schedule. In the other set, a thermocouple located on the surface of the drying slice exposed to the radiant heat flux measured the temperature continuously and cut off the infrared source automatically when the surface temperature reached 36 to 45°C. The effect of osmotic-IR conditions …

Go to article

Whispering Gallery Mode Lasers In Erbium/Ytterbium Codoped Phosphate Glasses, Tam Tran Thi, Trung Dang Quoc, Minh Le Huu, Vu Tran Anh, Chung Do Ngoc, Feron Patrice Nov 2017

Whispering Gallery Mode Lasers In Erbium/Ytterbium Codoped Phosphate Glasses, Tam Tran Thi, Trung Dang Quoc, Minh Le Huu, Vu Tran Anh, Chung Do Ngoc, Feron Patrice

ASEAN Journal on Science and Technology for Development

The study of whispering gallery mode laser in Er3+/Yb3+ co-doped phosphate glass microsphere has been reported. The coupling was carried out by fiber half taper technique. The microsphere lasers have been studied under pumping at 980 nm, to take full advantage of energy transfer effect from ion Ytterbium to ion Erbium. The observed lasing range extends from 1533 nm to 1612 nm.

Go to article

Photoluminescence Of Zno Nanostructure Prepared By Catalyst - Assisted Vapor - Liquid - Solid Technique, Hoa Tran Thi Quynh, Canh Ta Dinh, Long Nguyen Ngoc, Tuyen Nguyen Viet, Phuong Nguyen Duy Nov 2017

Photoluminescence Of Zno Nanostructure Prepared By Catalyst - Assisted Vapor - Liquid - Solid Technique, Hoa Tran Thi Quynh, Canh Ta Dinh, Long Nguyen Ngoc, Tuyen Nguyen Viet, Phuong Nguyen Duy

ASEAN Journal on Science and Technology for Development

ZnO semiconductor nanostructures have been synthesized by thermal evaporation of mixture of ZnO and graphite powders. The thin layer of gold coated on Si substrates was used as a catalyst. The structure analysis shows high crystallinity of ZnO, their preferred orientation along the (0 02) plane of the wurtzite phase and their chemical purity. The scanning electron microscopy (SEM) images of products indicate that ZnO nanowires have a diameter of about 40 - 150 nm and a length of up to tens of micrometers. The morphology and structure of ZnO nanowires and nanorods depend on the thicknesses of the Au …

Go to article

Synthesis And Characteristics Of Poly(Para-Phenylenevinylene), Chau Pham Thi Minh, Jin Jung Il Nov 2017

Synthesis And Characteristics Of Poly(Para-Phenylenevinylene), Chau Pham Thi Minh, Jin Jung Il

ASEAN Journal on Science and Technology for Development

Poly(para-phenylenevinylene) [PPV] films and nanotubes were prepared via chemical vapor deposition polymerization (CVDP) by vapor phase pyrolysis of α, α'-dichloro p-xylene on the quartz plate, silicon wafers and Al2O3 membrane substrate with the pore size f = 100 nm. We prepared graphitic carbon films and carbon nanotubes by carbonizing the poly(para-phenylenevinylene) [PPV] films and nano parterns under thermal treatment range from 500°C to 900°C. When the PPV films on quartz plate were treated at 900°C highly oriented graphitic carbon films were obtained. The characterization of the PPV nanotube and nanotube carbon has been investigated by means of IR, SEM, AFM …

Go to article

Magneto-Optic Properties And Oxidation/Reduction Of Ultrathin Magnetic Films: Fe Films On Pt(111), Nahm T.-U. Nov 2017

Magneto-Optic Properties And Oxidation/Reduction Of Ultrathin Magnetic Films: Fe Films On Pt(111), Nahm T.-U.

ASEAN Journal on Science and Technology for Development

We have investigated magneto-optic properties of ultrathin Fe films grown on Pt(111) surfaces by using the in situ surface magneto-optic Kerr effect (SMOKE) and X-ray photoelectron spectroscopy (XPS). SMOKE measurements show that the Fe layers are not ferromagnetic when the film is thinner than approximately 4.5 MLs (monolayers), but the in-plane magnetization is present for a 4.1 ML Fe film on Pt(111) annealed at 550 K. Upon post-annealing at 770 K, a 9.2 ML Fe film does not show any Kerr signal, while a 6.3 ML Fe film has the in-plane Kerr signal with increased coercivity. The oxidation and reduction …

Go to article

Experimental Study Of 3d Self-Assembled Photonic Crystals And Colloidal Core-Shell Semiconductor Quantum Dots, Nga Pham Thu, Chinh Vu Duc, Nghia Nguyen Xuan, Huy Nguyen Viet, Thuan Dao Nguyen, Cuong Pham Thai, Ha Chu Viet, Chi Do Do, Dat Nguyen Nhu, Anh Le A Lan, Barthou C., Benalloul P., Romanelli M., Maã®Tre A. Nov 2017

Experimental Study Of 3d Self-Assembled Photonic Crystals And Colloidal Core-Shell Semiconductor Quantum Dots, Nga Pham Thu, Chinh Vu Duc, Nghia Nguyen Xuan, Huy Nguyen Viet, Thuan Dao Nguyen, Cuong Pham Thai, Ha Chu Viet, Chi Do Do, Dat Nguyen Nhu, Anh Le A Lan, Barthou C., Benalloul P., Romanelli M., Maã®Tre A.

ASEAN Journal on Science and Technology for Development

In this contribution we present an experimental study of 3D opal photonic crystals. The samples are opals constituted by colloidal silica spheres, realized with self-assembly technique. The sphere diameter is selected in order to obtain coupling of the photonic band gap with the emission from CdSe/ZnS colloidal quantum dots. The quantum dots infiltrated in the opals is expected to be enhanced or suppressed depending on the detection angle from the photonic crystal. The structural and optical characterization of the SiO2 opal photonic crystals are performed by field-emission scanning electron microscopy and reflectivity spectroscopy. Measurements performed on samples permits to put …

Go to article

Synthesis And Photoluminescence Studies On Zinc Oxide Nanowires, Long Nguyen Ngoc, Dai Ngo Xuan, Hien Nguyen Thi Thuc Nov 2017

Synthesis And Photoluminescence Studies On Zinc Oxide Nanowires, Long Nguyen Ngoc, Dai Ngo Xuan, Hien Nguyen Thi Thuc

ASEAN Journal on Science and Technology for Development

Semiconductor single crystal ZnO nanowires have been successfully synthesized by a simple method based on thermal evaporation of ZnO powders mixed with graphite. Metallic catalysts, carrying gases, and vacuum conditions are not necessary. The x-ray diffraction (XRD) analysis shows that the ZnO nanowires are highly crystallized and have a typical wurtzite hexagonal structure with lattice constants a = 0.3246 nm and c = 0.5203 nm. The scanning electron microscopy (SEM) images of nanowires indicate that diameters of the ZnO nanowires normally range from 100 to 300 nm and their lengths are several tens of micrometers. Photoluminescence (PL) and photoluminescence excitation …

Go to article

Spin-Polarized Photocurrent Through Quantum Dot Photodetector, Hieu Nguyen Van, Ha Nguyen Bich Nov 2017

Spin-Polarized Photocurrent Through Quantum Dot Photodetector, Hieu Nguyen Van, Ha Nguyen Bich

ASEAN Journal on Science and Technology for Development

The theory of the photocurrent through the photodetector based on a two-level semiconductor quantum dot (QD) is presented. The analytical expressions of the matrix elements of the electronic transitions generated by the absorption of the circularly polarized photons are derived in the lowest order of the perturbation theory with respect to the electron tunneling interaction as well as the electron-photon interaction. From these expressions the mechanism of the generation of the spin-polarized of electrons in the photocurrent is evident. It follows that the photodetector based on the two-level semiconductor QD can be used as the model of a source of …

Go to article

First Prev Next Last