bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication and Characterization of TiO2-Doped ZnAl2O4 Nanocrystals via Sol-Gel Method for GPS Antenna
Authors: Abdullah Huda , Wan Jalal Wan Nasarudin , Zulfakar Mohd Syafiq , Islam Mohammad Tariqul , Bais Badariah , Shaari Sahbudin , Idris Sarada
Published: March 2016

The Zn(1-x)TixAl2O4 (x = 0.00, 0.05, 0.15 & 0.25) nanocrystals thin films were prepared by sol-gel method. The properties of Zn(1-x)TixAl2O4 were investigated by X-ray diffraction (XRD), Atomic Force Microscope (AFM), Fourier transform infrared spectra (FTIR) and (UV-Vis). By indexing the XRD patterns, we identified three structural types which is ZnAl2O4, anatase and rutile. The addition of TiO2 increased the crystallite size from 14.65 to 25.25 nm. The direct band gap was found to be around 3.35 to 3.84 eV. The addition of TiO2 increased the crystallite size, surface roughness, and lattice parameters of the resultant films, evidently affecting their density and dielectric constant (). The thin films were characterized in the certain frequency to determine the using LCR spectrometer. The and density value of the Zn(1-x)TixAl2O4 films increase linearly from 8.56 to 13.48 and 4.60 to 4.70 g/cm3 with the increasing of x value, respectively. Based on the material analysis and microwave antenna theory, GPS patch antennas were fabricated using the Zn(1-x)TixAl2O4 material. The fabricated GPS antenna with the highest (13.48) material exhibits the smallest size of antenna which is 7.45 cm2. The performances and the operating frequencies were measured using a PNA series network analyzer. The result showed that all patch antennas operate at frequency of 1.570 GHz. The GPS patch antenna fabricated from Zn0.25Ti0.75Al2O4 showed an excellent combination of return loss (-29.6 dB), smallest size (7.85 cm2), and wide bandwidth (195 MHz). All fabricated antennas are meets the requirements of GPS applications.
Structural and Optical Studies of Undoped Porous GaN Prepared by Pt-Assisted Electroless Etching
Authors: Mahmood Ainorkhilah , Hassan Zainuriah , Ahmed Naser Mahmoud , Yam Fong Kwong , Chuah Lee Siang , Mokhtar Marina , Mohd Noor Nurul Huda , Rosli Siti Azlina
Published: March 2016

Porous GaN structures were formed from crystalline GaN on conducting AL2O3 substrate using Pt-assisted electroless etching in HF: CH3OH: H2O2 = 1:4:4 under illumination of 500 W UV lamp. Scanning electron microscope (SEM) photoluminescence (PL) and Raman spectra measurements evidenced important features of the pore morphology, nanostructures and optical properties. According to the SEM micrographs, the three-dimensional ridge structure appears with the formation of porous material between the ridges. The porous layer exhibited a substantial PL intensity enhancement with red-shifted band-edge PL peaks associated with the relaxation of compressive stress. The shift of E2(high) to the lower frequency in Raman spectra of the porous GaN films further confirms such a stress relaxation.
Synthesis and Electrical Studies of Quaternary Chalcogenide Semiconductor Cu2ZnSnSe4
Authors: Jian Leong Yong , Chyi Josephine Liew Ying , Talib Zainal Abidin , Wan Yunus W. Wahmood , Ashari Fakhrurrazi , Kee Lee Han
Published: March 2016

Quaternary chalcogenide semiconductor has attracted much attention as absorber-layer materials in solar cells. The absorber-layer material, Cu2ZnSnSe4 (CZTSe) which is a p-type semiconductor that has high absorption coefficient, had been synthesized by using solvothermal method. The variation of concentrations of the Copper (II) Chloride dihydrate have brought some effects towards producing the stoichiometry and non-stoichiometry copper zinc tin selenide that may lead to the improvement of efficiency of solar cells. The synthesized reaction was conducted at 250°C for 24 hours. Properties of the samples have been characterized by X-ray diffraction (XRD) to determine the crystal structure of the sample and X-ray Fluorescence (XRF) to determine the elemental composition of the sample. The electrical properties such as resistance and conductivity have been studied through Van der Pauw configuration. The CZTSe has been successfully synthesized at concentrations of 0.15 M with no impurities phases existed.
The Treated Cellulose Micro/Nano Fibers (CMNF) from Bioresources in Malaysia
Authors: Abdul Aziz Fauziah , Ismail Ariffin , Yunus Wan MD Zin Wan , Mohamad Nor Norazman , Sohaimi Risby Mohd , Sulaiman Ahmad Zaidi , Abdul Halim Norhana , Daruis Dian Darina Indah , Azraaie Noriean , Zainul Abidin Nurul Aimi Mohd , Ibrahim Nur Ain , Mamat Razali Nur Amira
Published: March 2016

Cellulose Micro/Nano fibers (CMNF) from various plants which is Resak (Vatica spp.) waste, Merbau (Intsia bijuga) waste, banana (Musa acuminata) pseudo-stem and pineapple (Ananas comosus) leaf fibers have been isolated and characterized. Isolation of microfibril cellulose from raw fibers was achieved using alkaline treatment and bleaching. The treated and untreated samples were characterized using x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Characterizations of treated and untreated samples were compared. The comparison between those treated and untreated samples giving different crystallite size, crystallinity, arrangement of CMNF and surface morphology from different plants. Hence, with these information different nanocomposite from CMNF can be constructed and manipulated for various application.
Physicochemical Study of 3,4-Dichlorophenoxyacetic Acid Intercalated into Hydrotalcite-Like Compound by Ion Exchanged Method
Authors: Mohd Ghazali Sheikh Ahmad Izaddin Sheikh , Sarijo Siti Halimah , Hussein Mohd Zobir
Published: March 2016

The intercalation of herbicide, 3,4-dicholorophenoxyacetic acid (3,4D), into zinc-aluminium-layered double hydroxide (LDH) for the formation of a new nanocomposite ZADX, was accomplished via anion exchange method. Due to the intercalation of 3,4D with LDH interlayer domain, basal spacing expanded from 8.9Å in the ZAL to 17.7-19.0 Å in the ZADX. The percentage loading of 3,4D in the ZADX is 51.4 % (w/w). The FTIR spectra of the nanocomposite shows resemblance peaks of the 3,4D and Zn-Al-layered double hydroxide indicating the inclusion of 3,4D into the layered double hydroxide. Surface area of the resulting nanocomposite increased from 1.3 to 7.14 m2g-1 with the nitrogen adsorption-desorption of type IV.
Effect of 1-Ethyl-3-Methylimidazolium Nitrate on the Electrical Properties of Starch/Chitosan Blend Polymer Electrolyte
Authors: Khiar Azwani Sofia Ahmad , Anuar M.R.S. , Md Parid M.A.
Published: March 2016

Solid polymer electrolyte (SPE) can be viewed as an alternative of conventional liquid electrolyte since it is easier to handle. Previous Solid polymer electrolyte (SPE) can be viewed as an alternative of conventional liquid electrolyte since it is easier to handle. In the present work, starch/chitosan-ammonium nitrate (NH4NO3) SPE has been prepared by solution casting technique. Different amount of 1-ethyl-3-methylimidazolium nitrate ([EMIM][NO3]) was added to the sample. Ionic conductivity analysis was conducted over a wide range of frequency between 50 Hz-1 MHz using impedance spectroscopy to evaluate the dielectric properties and conductivity of the sample.Sample with 15 wt% of [EMIM][NO3] has shown the highest conductivity of 7.36 x 10-5 S cm-1 at room temperature. Complex permittivity for real (εr), imaginary (εi) and electrical modulus for real (Mr) and imaginary (Mi) part was determined and plotted.
Gold Nanoparticles Stimulated Surface Plasmon Resonance Effects in Erbium-Zinc-Sodium-Tellurite Glass
Authors: Ghoshal S.K. , Awang Asmahani , Sahar M.R. , Arifin R.
Published: March 2016

Modifying the optical characteristics of rare earth (RE) doped inorganic glasses by stimulating surface plasmon resonance (SPR) via controlled growth of metal nanoparticles (NPs) is an outstanding quest in glass plasmonics. Glasses with composition 70TeO2-20ZnO-10Na2O-(x)Er2O3-(y)Au (x = 0.0 and 1.0 mol%; y = 0.0 and 0.6 mol% both in excess) are synthesized using melt-quenching technique and characterized. Influences of heat treatment temperature on the growth of Au NPs and their subsequent impacts on Raman spectral features modifications are inspected. The amorphous nature of glass is confirmed by using XRD. TEM reveal the non-spherical Au NPs with average diameter vary from 7.4 to 10.3 nm. Surface plasmon band is evidenced around 627 - 632 nm. Raman spectra demonstrate the presence of Er-O and Zn-O bond, anti-symmetric vibrations of Te-O-Te bonds and stretching modes of non-bonded oxygen exists in TeO3 and TeO3+1 unit. The amplifications in Raman signals by a factor of 1.39, 1.40, 0.88 and 1.29 and 1.25 corresponding to the peak centered at 262, 382, 536, 670 and 725 cm-1 are attributed to the contribution of a surface plasmon (SP) generating a strong, localized and secondary field. The excellent features of the results suggest that our systematic method of controlled NPs growth may constitute a basis for improving the spectral features of tellurite glasses useful for the development of efficient and economic up-converted lasers.
X-Ray Diffraction and Infrared Studies on Plasticized Cellulose Acetate Complexed with Ammonium Iodide for Solid Polymer Electrolyte
Authors: Samsi Noor Syafiqah , Zakaria Rosnah , Hassan Oskar Hasdinor , Yahya Muhd Zu Azhan , Marwan Bin Ali Abdul Malik
Published: March 2016

Gel polymer electrolyte films based on cellulose acetate (CA) complexed with ammonium iodide (NH4I), and ethylene carbonate (EC) was prepared by the solution cast technique. The conductivity increases to 10-4 Scm-1 upon the addition of salt. The incorporation of EC and to the salted polymer enhances the conductivity significantly 10-3 Scm-1. The complexation of doping materials with polymer was confirmed by X-ray diffraction and infrared studies. The present of ethylene carbonate (EC) as plasticizer did not disturbed the complexation between polymer and salt that has been confirm by FTIR. XRD studies further confirmed that all sample prepared are crystalline. This result affirmed that there were no complexations occur between plasticizer in the CA-NH4I polymer system.
Effects of Dodecanoic Acid Modified SIO2 on Filler Dispersion and Ionic Conductivity of PMMA/ENR 50/LIBF4 Electrolytes
Authors: Siti Izzati Husna Mohd Azuan , Famiza Abdul Latiff , Sharil Fadli Mohamad Zamri
Published: March 2016

Previously, the addition of silicon dioxide (SiO2) improved the homogeneity of polymethyl methacrylate/50 % epoxidised natural rubber (PMMA/ENR 50) blend. However, the presence of SiO2 agglomerates limits its overall performance. The formation of these agglomerates was due to the hydrogen bonding interaction that form between the oxygen atoms in silanol groups (Si-OH) and hydrogen atoms from the surrounding moisture. Therefore, in this study, SiO2 were modified with dodecanoic acid (DOA) to reduce the number of Si-OH on the SiO2 surface using esterification technique. Interestingly, it was found that the addition of DOA modified SiO2 (D-SiO2) improves the homogeneity of PMMA/ENR 50 blend. However, the amount of DOA used in the modification affect the capability of forming hydrogen bonding with the neighbouring of polymer chain. Different amounts of DOA were used upon the surface modification of SiO2 filler and then were added into PMMA/ENR 50 blends doped with lithium tetrafluoroborate (LiBF4). The films were prepared by solvent casting technique. CHNS analysis proven the increases of percentage of carbon atoms in D-SiO2. The attachment of DOA on SiO2 surface was confirmed using Fourier transform infrared spectroscopy (FTIR) and ionic conductivity of PMMA/ENR 50/LiBF4 filled D-SiO2 films was measured by electrochemical impedance spectroscopy (EIS). The result shows the blend properties and ionic conductivity of PMMA/ENR 50 filled D-SiO2 films was improved due to surface modification of SiO2 filler.
Characterization of Proton Conducting Carboxymethyl Cellulose/Chitosan Dual-Blend Based Biopolymer Electrolytes
Authors: Rani Mohd Saiful Asmal , Mohamed Nor Sabirin , Isa Mohd Ikmar Nizam
Published: March 2016

This article presents the discovery on biopolymer electrolytes comprising of ammonium nitrate, NH4NO3 with dual-blend biopolymer materials, carboxymethyl cellulose/chitosan which were prepared via solution-casting technique. The biopolymer blend based electrolyte films were characterized by Fourier Transform Infrared spectroscopy to investigate the formation of the dual-blend biopolymer based complexes. X-Ray Diffraction result showed that all dual-blend samples were predominantly amorphous. Electrochemical impedance spectroscopy was conducted to obtain their ionic conductivities. The highest conductivity at ambient temperature of 1.03 × 10–5 S cm–1 was obtained for the electrolyte film containing 40 wt% of NH4NO3. These results indicated that the dual-blend biopolymer based electrolyte has potential for application of electrochemical devices.
Effect of KOH Treated Graphene in Green Monoliths of Pre-Carbonized Biomass Fibers on the Structure, Porosity and Capacitance of Supercapacitors Carbon Electrodes
Authors: Jasni Mohamad Redwani Mohd , Deraman Mohamad , Hamdan Ellisa , Sazali Noor Ezniera Shafieza , Nor Najah Syahirah Mohd , Ishak Maria Muhammad , Basri Nur Hamizah , Omar Ramli , Othman Mohd Amir Radhi , Zulkifli Roslinda , Daik Rusli , Suleman Mohd
Published: March 2016

Activated carbon monoliths (ACMs) electrodes for supercapacitor application were prepared from the green monoliths (GMs) containing KOH treated self-adhesive carbon grains (SACG) added with KOH treated graphene at its weight percentages of 0, 2, 4, 6, 8 and 10 %, respectively. The SACG were prepared from fibers of oil palm empty fruit bunches by a low carbonization temperature method. The ACMs were produced by the carbonization and activation of the GMs. The surface area, structure and specific capacitance of the ACMs electrodes were found affected by the graphene addition. The highest surface area of the ACMs electrode was observed for the addition of 6% graphene, which corresponds to the carbon turbostratic structure of the ACMs electrodes with the values of its crystallites interlayers spacing (d002 and d100) at 0.352 nm and 0.205 nm, and its crystallites stack-width (La) and stack-height (Lc) at 43.21 nm and 10.06 nm, respectively. The specific capacitance of the cell using this electrode was 112 F / g.
Charge Distribution in YBa2Cu3O7  and YBa2Cu4O8 by Density Functional Theory
Authors: Cheong Choon Min , Rahman Md Mahmudur , Shaari Abdul Halim , Chen Soo Kien
Published: March 2016

In this work, we analyze the electronic structure and charge distribution of the YBCO family compounds Y-123 and Y-124 bulk using the density functional theory. The band structures and the density of states of the compounds are shown. The charge transfers between the atoms in the two compounds are compared and discussed in detail. The lattice parameters obtained by Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm are compared with the experimental parameters. The critical differences of the charge distribution for these two compounds are discussed.
Influence of Rare-Earth (Doped) on Low-Density Bi1.6Pb0.4Sr2Ca1.9RE0.1Cu3Oδ (RE=Nd, Er) Superconductors via Co-Precipitation Method
Authors: Azhan H. , Syuhaida I.N. , Azman K. , Azura C.M.N. , Robaiah M. , Syamsyir S. Akmal , Rosli Mohd Mustaqim
Published: March 2016

Effect of Ca doped by rare-earth elements, Nd and Er (x=0.10) on the structural and transport properties of low density Bi1.6Pb0.4Sr2Ca1,9RE0.1Cu3Oδ (RE=Nd,Er) samples have been investigated. The samples have been prepared via co-precipitation (COP) method from precipitate of saturated solutions of metal acetates, iso-propanol solution and oxalic acid. The metal oxalates powder was subjected to thermal treatment of 24 hours calcination at 845oC and mixed with 0.10 g sucrose C12H22O11 which is used as supplementary filler. The pelletized powder was heated for 2 hours at 400 oC and sintered for at 850oC for 48 hours. All samples show a single step transition in the R-T curves. The critical current density (Jc) and transition temperature (Tczero) for both Nd and Er doped with x = 0.10 were found to be lower than standard samples. Tczero obtained varies between 98 K and 66 K. XRD data showed the decrease of volume fraction for the Bi-2223 phase and increase of the volume fraction Bi-2212 phase with the doping of Nd and Er.
The Influence of Ce-Doping on Structural and Superconducting Properties in Low-Density Bi1.6Pb0.4Sr2Ca2-xCexCu3Oy Superconductor
Authors: Robaiah M. , Azhan H. , Azman K. , Syamsyir S. Akmal , Syuhaida I.N. , Azura C.M.N. , Rosli Mohd Mustaqim
Published: March 2016

The influences of cerium doped on low density Bi-2223 superconductor have been studied and this study examines the significant changes in the structural and superconducting properties. The nominal compositions of low density Bi1.6Pb0.4Sr2Ca2-xCexCu3Oy (where x =0.000, 0.025, 0.05, 0.1 and 0.2) ceramic superconductor were prepared by solid state method. The effects of different Ce doping levels on the superconductor structure and superconducting properties has been investigated by field emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), electrical resistance and transport critical current density (JC) measurements. The results show that TC zero and JC of the samples reduced gradually with the increase in the Ce addition. It has been observed that, the JC of low density Bi-2223 for Ce-free was measured to be 12.120 A/cm2 and 0.448 A/cm2 in x=0.025 at 60 K under zero magnetic field. As for XRD analysis showed the doping of Ce reduced the volume fraction of the 2223 phase and increased the volume fraction of the 2212 phase. FESEM results showed the surface morphology not homogenous and weak links between superconducting grains of the samples due to increase of the Ce doping.
Influence Different Compositions of (1-x)ZnFe2O4 – xSiO2 Nanostructures Thin Film Synthesized by Sol-Gel Method
Authors: Zulfakar Mohd Syafiq , Abdullah Huda , Wan Jalal Wan Nasarudin , Zainuddin Zalita , Shaari Sahbudin
Published: March 2016

SiO2 compound was introduced into zinc ferrite using formula (1-x)ZnFe2O4 – xSiO2 synthesized by sol-gel method where distilled water and citric acid was used as a solvent and binder agent. The produced samples were annealed at 450 °C for 1h. The AFM result analysis show that the average surface roughness and particle size decreased as the compositions of x was increased. XRD results analysis confirmed the formation of spinel structures with crystallite size within range 11.27 – 4.72 nm. UV-Vis analysis to determine the energy band gap of the (1-x)ZnFe2O4 – xSiO2 samples. It shows that the energy band gap increased as the composition of SiO2 was increased due to the dielectric properties of silicon dioxide. FTIR results analysis exhibit common band in the range of 400 – 4000 cm-1. The observed band near 2350 cm-1 shows the presence of oxygen-oxygen bond in the face centered cubic (fcc) crystal lattice of oxygen atoms. The addition of SiO2 into ZnFe2O4 will help to enhance the morphological structures and optical properties. This new proposed dielectric material can be used as dielectric substrate microstrip patch antenna.
Polarized Infrared Reststrahlen Features of Wurtzite InGaN Thin Film
Authors: Yew Pauline , Cheong Lee Sai , Shiong Ng Sha , Leong Yoon Tiem , Hassan Haslan Abu , Chen Wei Li
Published: March 2016

Polarized infrared (IR) reflectance measurement was carried out to investigate the optical phonon modes of wurtzite structure In0.92Ga0.08N thin film grown by molecular beam epitaxy. Composition dependence of IR reststrahlen features was observed. Theoretical polarized IR reflectance spectrum was simulated using the standard multilayer optics technique with a multi-oscillator dielectric function model. By obtaining the best fit of experimental and theoretical spectrum, the Brillouin zone center E1 optical phonon modes together with the dielectric constant, layer thickness, free carriers concentration and mobility were extracted non-destructively. The extracted E1 optical phonon modes were compared with those generated from modified random element isodisplacement (MREI) model.
Isolation of Microfibrillated Cellulose (MFC) from Local Hardwood Waste, Resak (Vatica spp.)
Authors: Zainul Abidin Nurul Aimi Mohd , Abdul Aziz Fauziah , Radiman Shahidan , Ismail Ariffin , Wan Yunus Wan Md Zin , Mohamad Nor Norazman , Sohaimi Risby Mohd , Sulaiman Ahmad Zaidi , Abdul Halim Norhana , Daruis Dian Darina Indah
Published: March 2016

Micrifibrillated cellulose (MFC) is generally can be prepared either by acid hydrolysis, chemical treatments, or by a high pressure refiner. In this study, the MFC of Resak’s hardwood waste with high degree of crystallinity has been obtained by an acid hydrolysis using mineral acid H2SO4. The microstructures of the MFC were characterized via X-ray diffraction (XRD) and Field emission scanning electron microscope (FESEM).
The Preparation and Physical Characteristic of Sm3+ Doped Borotellurite Glass
Authors: Mohd Rafien Siti Nasuha , Azman K. , Azhan H. , Senawi S.A. , Abdullah Mardhiah
Published: March 2016

Borotellurite glasses were generally applied in rare earth optical materials due to their excellent physical properties. Samarium doped borotellurite glasses have been identified as one of the potential candidate for optical applications. Therefore, the aim of this study is to identify the physical properties of Sm3+ doped borotellurite glasses by mean of their density, molar volume, microhardness and X-ray diffraction. In this study, the Sm3+ doped borotellurite glasses of the system (70-x)TeO2-20B2O3-10ZnO-xSm2O3 as the samarium trioxide varies from (x = 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 mol%) have been prepared by melt-quenching method. The amorphous nature of the prepared glass samples have been confirmed through XRD spectral analysis. The values of density are found to vary from 4.541g/cm3 to 4.837g/cm3 as well as the values of molar volume as it varies from 29.118cm3/mol to 28.314cm3/mol with the increase of Sm3+ content. The physical properties corresponding to compositional changes have been analysed and the result are reported and presented.
Synthesis of Waste Cooking Oil-Based Polyol Using Sugarcane Bagasse Activated Carbon and Transesterification Reaction for Rigid Polyurethane Foam
Authors: Mohd Tahir Syuhada , Wan Salleh Wan Norfirdaus , Nor Hadid Nur Syahamatun , Enderus Nor Fatihah , Ismail Nurul Aina
Published: March 2016

This study was carried out to determine the potential of waste cooking oil (WCO) in preparation of rigid polyurethane (PU) foam. The raw WCO was first filtered and adsorbed by using sugarcane bagasse activated carbon in order to purify the oil. Next, the adsorbed WCO was used to synthesize polyol via transesterification reaction. The WCO-based polyol was then combined with other chemicals at various ratios to form PU rigid foam. The adsorbed WCO showed the decrease in both free fatty acid percentage and viscosity, from 4.3 % to 0.77 % and from 106 mPa.s to 72.5 mPa.s, respectively. No alteration of functional group observed after adsorption as proven by FTIR spectroscopy. The FTIR spectrum of WCO-based polyol showed the formation of OH absorption peak and supported by the increase in hydroxyl value from 0 to 148.79 mgKOH/g after reaction. The formation of urethane linkages (NHCO) backbone in PU foam was confirmed using FTIR. The properties of PU foam are highly dependent on the chemical composition. The density and compressive strength of 60:54:90:40 of glycerol:water:polyol:amine polyurethane foam are 277.7 kg/m3 and 0.10 MPa, respectively. This study showed that WCO exhibit promising potential as raw material for PU formation.
Non-Resonance Acousto-Optics Signal Analysis from Photonics Microphone Using 1 mW Laser
Authors: Mohdami Norashid Muhammad Adib Akram , Abd-Rahman M. Kamil
Published: March 2016

This paper presents an acousto-optics analysis on free space optical signals modulated by two distinguishable non-resonant acoustic waves. The acoustic waves were directed at two different directions and locations along a laser beam and created non-interference modulated optical signals. The photonics microphone deploys low-powered eye-safe continuous-wave 633-nm laser; high-speed photodiode and a series of Fourier lenses. Two transducers generating 20 Hz to 20 kHz acoustic waves were directed across the laser beam. The receiving modulated signal was filtered and amplified electronically by two sets of passive bandpass filter separated by a transimpedance amplifier and connected to a computer for analysis. The signal was further digitally filtered and amplified to enhance the signal-to-noise ratio via MATLAB software. These signals were analyzed in time and frequency domains using Fast Fourier Transform (FFT) and Spectrogram. It was found that the recorded signals demonstrated higher signal intensities for lower acoustic frequencies with digital signal-to-noise ratio (SNR) ranging from 10.77 to 71.92 for frequency of 1 kHz to 20 kHz and 20 Hz to 1 kHz respectively. The frequencies of both transducers were simultaneously swept through from 20 Hz and 20 kHz respectively. These scanning frequencies approached one another and crossover with no resonant frequency was observed. This illustrates that it is able to detect multiple acoustic signals for any given frequencies along the laser beam and found its applications in stealth sound detection and long range sound sensor. Though low-powered 1-mW laser was used, a relatively high signal-to-noise ratio with clear-recorded playback was achieved.
Luminescence Properties of Eu3+ and Dy3+ Doped Magnesium Tellurite Borophosphate Glass
Authors: Aziz Siti Maisarah , Hussin Rosli
Published: March 2016

The luminescence properties of rare earth in glass are interesting to study and being one of attractive properties in development of laser. A series of Eu3+/Dy3+ co-doped magnesium tellurite borophosphate glass has been prepared with nominal composition 50B2O3-15P2O5-25MgO-10TeO2. The amorphous phases of the sample were characterized using X-ray diffraction pattern and the presence of a broad hunch shows that the sample in an amorphous state. For Eu3+/Dy3+ co-doped borophosphate glass sample of consist five peaks where Eu3+ emission were located at 611 nm, 662 nm and 699 nm due to the transition of 5D0-7FJ ( J = 2, 3, 4) while the Dy3+ emission is due to transition 4F9/2-5HJ/2 (J = 15 and 13). Furthermore, glass sample showed exponential decay curve and lifetime for glass sample is determined.
Tuning Surface Plasmon in Erbium-Boro-Tellurite Nanoglass via Thermal Annealing
Authors: Mahraz Zahra Ashur , Sahar M.R. , Ghoshal Sib Krishna
Published: March 2016

The demand for tunable surface plasmon (SP) of embedded metal nanoparticles (NPs) in rare earth doped inorganic lasing glasses is ever-growing. Following melt quenching method Er3+ doped zinc-boro-tellurite glasses containing silver (Ag) NPs are prepared. Glasses are heat treated (thermally annealed) at varying temperatures and time duration to alter the NPs morphology which generates SP. The annealing assisted SP resonance mediated modification in spectral features is discerned. Samples heat treatment at 410 °C for 6 hrs duration ensures the reduction of Ag+ ions to Ago NPs. Thermally annealed glasses are characterized via XRD, UV–Vis-IR absorption, photoluminescence spectroscopy, and TEM imaging. XRD spectra confirm the amorphous nature of the glass and TEM image reveals the existence of homogeneously distributed spherically shaped silver NPs of average diameter ~4.5 nm. NPs are found to grow with the increase of both annealing time and temperature. The UV–Vis spectra exhibit seven absorption bands corresponding to 4f–4f transitions of Er3+ ions in the wavelength range of 500-650 nm. The localized SPR band is evidenced at 550 and 580 nm. Heat treatment causes a red shift of the plasmon peaks ascribed to the alteration in glass refractive index. Furthermore, the glass sample annealed for 6 hrs displays maximum enhancement in the emission intensity corresponding to the peaks centered at 536 (2H11/2→4I15/2), 550 (4S3/2→4I15/2) and 632 nm (4F9/2→4I15/2). This enhancement is primarily attributed to the local field effect of the silver NPs. Admirable features of the results suggest that our systematic method for heat treatment in tuning NPs size assisted SPR may contribute towards the development of functional glass.
Climatic impacts of stratospheric geoengineering with sulfate, black carbon and titania injection
Authors: Jones Anthony C. , Haywood James M. , Jones Andy
Published: March 2016

Abstract. In this paper, we examine the potential climatic effects of geoengineering by sulfate, black carbon and titania injection against a baseline RCP8.5 scenario. We use the HadGEM2-CCS model to simulate scenarios in which the top-of-the-atmosphere radiative imbalance due to rising greenhouse gas concentrations is offset by sufficient aerosol injection throughout the 2020–2100 period. We find that the global-mean temperature is effectively maintained at historical levels for the entirety of the period for all three aerosol-injection scenarios, though there is a wide range of side-effects which are discussed in detail. The most prominent conclusion is that although the BC injection rate necessary to produce an equivalent global mean temperature response is much lower, the severity of stratospheric temperature changes (> +70 °C) and precipitation impacts effectively exclude BC from being a viable option for geoengineering. Additionally, while it has been suggested that titania would be an effective particle because of its high scattering efficiency, it also efficiently absorbs solar ultraviolet radiation producing a significant stratospheric warming (> +20 °C). As injection rates and climatic impacts for titania are close to those for sulfate, there appears to be little benefit in terms of climatic influence of using titania when compared to the injection of sulfur dioxide, which has the added benefit of being well-modeled through extensive research that has been carried out on naturally occurring explosive volcanic eruptions.
Aerosol effective density measurement using scanning mobility particle sizer and quartz crystal microbalance with the estimation of involved uncertainty
Authors: Sarangi Bighnaraj , Aggarwal Shankar G. , Sinha Deepak , Gupta Prabhat K.
Published: March 2016

Abstract. In this work, we have used a scanning mobility particle sizer (SMPS) and a quartz crystal microbalance (QCM) to estimate the effective density of aerosol particles. This approach is tested for aerosolized particles generated from the solution of standard materials of known density, i.e. ammonium sulfate (AS), ammonium nitrate (AN) and sodium chloride (SC), and also applied for ambient measurement in New Delhi. We also discuss uncertainty involved in the measurement. In this method, dried particles are introduced in to a differential mobility analyser (DMA), where size segregation is done based on particle electrical mobility. Downstream of the DMA, the aerosol stream is subdivided into two parts. One is sent to a condensation particle counter (CPC) to measure particle number concentration, whereas the other one is sent to the QCM to measure the particle mass concentration simultaneously. Based on particle volume derived from size distribution data of the SMPS and mass concentration data obtained from the QCM, the mean effective density (ρeff) with uncertainty of inorganic salt particles (for particle count mean diameter (CMD) over a size range 10–478 nm), i.e. AS, SC and AN, is estimated to be 1.76 ± 0.24, 2.08 ± 0.19 and 1.69 ± 0.28 g cm−3, values which are comparable with the material density (ρ) values, 1.77, 2.17 and 1.72 g cm−3, respectively. Using this technique, the percentage contribution of error in the measurement of effective density is calculated to be in the range of 9–17 %. Among the individual uncertainty components, repeatability of particle mass obtained by the QCM, the QCM crystal frequency, CPC counting efficiency, and the equivalence of CPC- and QCM-derived volume are the major contributors to the expanded uncertainty (at k = 2) in comparison to other components, e.g. diffusion correction, charge correction, etc. Effective density for ambient particles at the beginning of the winter period in New Delhi was measured to be 1.28 ± 0.12 g cm−3. It was found that in general, mid-day effective density of ambient aerosols increases with increase in CMD of particle size measurement but particle photochemistry is an important factor to govern this trend. It is further observed that the CMD has good correlation with O3, SO2 and ambient RH, suggesting that possibly sulfate secondary materials have a substantial contribution in particle effective density. This approach can be useful for real-time measurement of effective density of both laboratory-generated and ambient aerosol particles, which is very important for studying the physico-chemical properties of particles.
Nordic Snow Radar Experiment
Authors: Lemmetyinen Juha , Kontu Anna , Pulliainen Jouni , Vehviläinen Juho , Rautiainen Kimmo , Wiesmann Andreas , Mätzler Christian , Werner Charles , Rott Helmut , Nagler Thomas , Schneebeli Martin , Proksch Martin , Schüttemeyer Dirk , Kern Michael , Davidson Malcolm
Published: March 2016

Abstract. The objective of the Nordic Snow Radar Experiment (NoSREx) campaign was to provide a continuous time series of active and passive microwave observations of snow cover in a representative location of the Arctic boreal forest area, covering a whole winter season. The activity was a part of Phase A studies for the ESA Earth Explorer 7 candidate mission CoReH2O (Cold Regions Hydrology High-resolution Observatory). The NoSREx campaign hosted two main microwave instruments; a frequency scanning scatterometer operating on frequencies from X- to Ku band, and a microwave dual-polarization radiometer system operating from X- to W-bands. In situ measurements consisted of manual snow pit measurements at the main test site as well as extensive automated measurements on snow, ground and meteorological parameters. This study provides a summary of the obtained data, detailing measurement protocols for both microwave instruments and in situ reference data. A first analysis of the microwave signatures against snow parameters is given. All data, including the raw data observations, are available through the European Space Agency and the Finnish Meteorological Institute for research purposes. A consolidated dataset of observations, comprising of the key microwave and in situ observations, is provided through the ESA campaign data portal to enable easy access to the data.
Addressing numerical challenges in introducing a reactive transport code into a land surface model: a biogeochemical modeling proof-of-concept with CLM–PFLOTRAN 1.0
Authors: Tang Guoping , Yuan Fengming , Bisht Gautam , Hammond Glenn E. , Lichtner Peter C. , Kumar Jitendra , Mills Richard T. , Xu Xiaofeng , Andre Ben , Hoffman Forrest M. , Painter Scott L. , Thornton Peter E.
Published: March 2016

Abstract. We explore coupling to a configurable subsurface reactive transport code as a flexible and extensible approach to biogeochemistry in land surface models. A reaction network with the Community Land Model carbon–nitrogen (CLM-CN) decomposition, nitrification, denitrification, and plant uptake is used as an example. We implement the reactions in the open-source PFLOTRAN (massively parallel subsurface flow and reactive transport) code and couple it with the CLM. To make the rate formulae designed for use in explicit time stepping in CLMs compatible with the implicit time stepping used in PFLOTRAN, the Monod substrate rate-limiting function with a residual concentration is used to represent the limitation of nitrogen availability on plant uptake and immobilization. We demonstrate that CLM–PFLOTRAN predictions (without invoking PFLOTRAN transport) are consistent with CLM4.5 for Arctic, temperate, and tropical sites.Switching from explicit to implicit method increases rigor but introduces numerical challenges. Care needs to be taken to use scaling, clipping, or log transformation to avoid negative concentrations during the Newton iterations. With a tight relative update tolerance (STOL) to avoid false convergence, an accurate solution can be achieved with about 50 % more computing time than CLM in point mode site simulations using either the scaling or clipping methods. The log transformation method takes 60–100 % more computing time than CLM. The computing time increases slightly for clipping and scaling; it increases substantially for log transformation for half saturation decrease from 10−3 to 10−9 mol m−3, which normally results in decreasing nitrogen concentrations. The frequent occurrence of very low concentrations (e.g. below nanomolar) can increase the computing time for clipping or scaling by about 20 %, double for log transformation. Overall, the log transformation method is accurate and robust, and the clipping and scaling methods are efficient. When the reaction network is highly nonlinear or the half saturation or residual concentration is very low, the allowable time-step cuts may need to be increased for robustness for the log transformation method, or STOL may need to be tightened for the clipping and scaling methods to avoid false convergence.As some biogeochemical processes (e.g., methane and nitrous oxide reactions) involve very low half saturation and thresholds, this work provides insights for addressing nonphysical negativity issues and facilitates the representation of a mechanistic biogeochemical description in Earth system models to reduce climate prediction uncertainty.
March 2016 Problems
Authors: Roscoe Matt B. , Pelikan Stephan
Published: March 2016

Abstract: A monthly set of problems is aimed at a variety of ability levels.
Mestizaje y frontera en las tierras del Pacífico del Nuevo Reino de Granada, siglos XVI y XVII
Authors: Montoya Guzmán Juan David
Published: March 2016

The objective of this article is to analyze the different relations of miscegenation that occurred in the Pacific territory of the New Kingdom of Granada during the first two centuries of European occupation. The study reveals that, contrary to what a broad sector of historiography has sustained, the Conquest was not unilateral and compact, but rather a discontinuous and heterogeneous process that permitted the rise of new groups such as the Mestizos. When these groups were educated in the colonial world, they participated actively in the wars against the Indians, but when they were brought up within the indigenous societies, they also knew how to attack the Conquistadors. The study uses different sources to analyze the process of miscegenation not only from the biological perspective, but from the cultural perspective as well. It is thus possible to understand how an intense process of racial-mixing known as mestizaje took place on both sides of the colonial boundary line.
De antiguos territorios coloniales a nuevas fronteras republicanas: la Guerra de Castas y los límites del suroeste de México, 1821-1893
Authors: Caso Barrera Laura , Aliphat Fernández Mario M.
Published: March 2016

Through the analysis of archival material, mainly cartographic, this article explores the processes of territorial delimitation between the province of Yucatan and El Petén, as well as of the region then occupied by the British (present-day Belize). The elaboration of reports and maps for the establishment of limits and borders between provinces, and later between nation states, reflects the policies of those states regarding the establishment of their territories. In this context it studies the impact that the indigenous uprising known as the War of the Castes had on the process of establishing limits and borders.
La organización sindical de los trabajadores gráficos de Mendoza durante la dictadura militar de la Revolución Argentina (1966-1973)
Authors: Emili Marcela
Published: March 2016

This article explores the trajectory of the graphic workers of Mendoza during the military dictatorship of the Argentine Revolution. These workers were recognized as “combative” by members of the labor movement of the period and by the press of the era, despite being a sector that did not play any leading role in the struggles of those years. In order to explain this paradox, this article inquires into the internal dynamics of the organization, its union strategies, and the positions it adopted with respect to other labor organizations and with respect to the dictatorship itself. Through the analysis of union documents—the minutes of Assemblies and Steering Committee Meetings— and interviews of graphic workers of the period, it reveals internal and external aspects of this guild and the graphic trade itself.
Silicon rib waveguide electro-absorption optical modulator using transparent conductive oxide bilayer
Authors: Ayata Masafumi , Nakano Yoshiaki , Tanemura Takuo
Published: March 2016

We propose a novel ultra compact electro-absorption optical modulator based on a silicon rib waveguide and numerically demonstrate its performance. The proposed design employs two types of transparent conductive oxide (TCO) layers with different carrier densities to achieve both high modulation efficiency and low optical insertion loss. The thin TCO layer with high carrier density enables efficient modulation through the metal–oxide–semiconductor structure. On the other hand, the upper TCO layer with low carrier density allows low-resistance electrical contact for the top electrode without large optical loss. Using an indium tin oxide bilayer with optimized carrier densities, we numerically demonstrate a 4.3 dB extinction ratio and a 2.6 dB optical insertion loss with 1 µm device length. We estimate that the modulator operates under a low driving voltage of 1.3 V, exhibiting an ultra low energy consumption of 22.5 fJ/bit and a broad RC modulation bandwidth of over 40 GHz.
Verification of EB3 specifications using CADP
Authors: Vekris Dimitris , Lang Frédéric , Dima Catalin , Mateescu Radu
Published: March 2016

E
B

3

is a specification language for information systems. The core of the

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B

3

language consists of process algebraic specifications describing the behaviour of the entities in a system, and attribute function definitions describing the entity attributes. The verification of

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B

3

specifications against temporal properties is of great interest to users of

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B

3

. In this paper, we propose a translation from

E
B

3

to LOTOS NT (LNT for short), a value-passing concurrent language with classical process algebra features. Our translation ensures the one-to-one correspondence between states and transitions of the labelled transition systems corresponding to the

E
B

3

and LNT specifications. We automated this translation with the

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B

3

2

L
N
T

tool, thus equipping the

E
B

3

method with the functional verification features available in the CADP toolbox.
Intra‐Operative Indocyanine Green Angiography of the Parathyroid Gland
Authors: Vidal Fortuny Jordi , Karenovics Wolfram , Triponez Frederic , Sadowski Samira M.
Published: March 2016

Major complications of thyroid and parathyroid surgery are recurrent laryngeal nerve injuries and definitive hypoparathyroidism. The use of intra‐operative Indocyanine Green Angiography for confirmation of vascular status of the parathyroid gland is reported here.
Benefits of group cognitive remediation therapy in anorexia nervosa: case series
Authors: Tchanturia Kate , Larsson Emma , Brown Amy
Published: March 2016

Background

Cognitive remediation therapy (CRT) is a treatment targeting cognitive difficulties in psychiatric disorders. CRT has been used with patients with severe anorexia nervosa (AN) in individual and group formats. Research of group CRT in AN is limited.

Methods

Evaluation of a series of CRT groups delivered in inpatient and intensive daycare services was performed. Participants’ self-reported cognitive flexibility and central coherence, as well as motivation to change were assessed pre- and post-group. Additionally, patients’ evaluative feedback was collected after completion of the group.

Results

There was a significant improvement in the patients’ self-reported cognitive flexibility and bigger picture thinking, as well as in their self-efficacy to change. The feedback questionnaires highlighted that patients found the sessions useful and reported confidence in using some of the skills and strategies they learnt in the group.

Conclusion

In line with evidence from small-scale reports, this larger scale case series study indicates that group CRT leads to increased flexibility and bigger picture thinking, as well as improved confidence in the ability to change for participants. CRT in a group format seems to be a practical and helpful intervention for patients with AN in intensive treatment programmes.
Intrauterine Transfusion
Authors: Deka Dipika
Published: March 2016

The mainstay of management of an Rh isoimmunized pregnancy is the early identification of fetal anemia. Ultrasound middle cerebral artery-peak systolic velocity (MCA-PSV) Doppler measurements are very useful to diagnose severe disease, to time delivery/serial intrauterine transfusions, and eliminate need of amniocentesis/cordocentesis. Fetal blood sampling is done if the fetus is hydropic or MCA-PSV is >1.5 MoM. Blood is kept ready for transfusion if fetal anemia is detected (hematocrit <30 %). Intravascular transfusion is preferred, especially in hydropic fetuses. Rarely, intraperitoneal transfusion is performed in certain situations when the approach to cord is difficult—posterior placenta, obesity, and very early gestation. Blood is absorbed through the lymphatics. Ultrasound and color Doppler is done for fetal heart activity, placental site, cord insertion, and accessible site. The needle path is mapped and decision is taken on where to enter the cord—cord insertion/free loop/intrahepatic portion site. A 20 gauge long needle is inserted under continuous ultrasound guidance into the umbilical vein, 2–3 mL blood aspirated for hemoglobin, packed cell volume, and blood group. Necessary volume of packed O-ve, irradiated red blood cell (hematocrit of 75–80 %) is then transfused. Fetal monitoring is done by serial ultrasound for anemia, MCA-PSV to time next transfusion, and fetal wellbeing—daily kick counts, ultrasound, and electronic biophysical profile. Neonatal management is by intensive fetal anemia and jaundice monitoring, use of intravenous immunoglobulin, exchange transfusion, and phototherapy. The improvement in outcome of Rh immunized fetuses is primarily due to improved expertise, better ultrasound machines, intrauterine blood transfusion, and improved neonatal care. From July 1997 to September 2015, there were 1022 transfusions performed in one Unit at AIIMS, with an overall successful outcome of 90–94 %. Fetal survival is low if hydropic or with first transfusion at 20 weeks or less. Care during the procedure will help to further improve safety. In conclusion, treatment of fetal anemia in Rh isoimmunization by ultrasound-guided fetal blood transfusions is relatively safe in experienced hands, permits a near-term delivery in majority of cases of this potentially life-threatening fetal disease.