bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural, Morphological, Photovoltaic and Electron Transport Properties of ZnO Based DSSC with Different Concentrations of MWCNTs
Authors: Mahalingam Savisha , Abdullah Huda , Razali Mohd Zikri , Yarmo Mohd Ambar , Shaari Sahbudin , Omar Azimah
Published: March 2016

This study highlights the structural, morphological, photovoltaic and electron transport properties of zinc oxide-multi-walled carbon nanotubes (ZnO-MWCNTs) based dye-sensitized solar cell (DSSC) prepared at different concentrations of 0.0, 0.1, 0.3 and 0.5 wt.%. The ZnO-MWCNTs thin films were prepared by a chemical bath deposition method. X-ray diffraction (XRD) analysis proved the formation of hexagonal wurtzite of the samples. The crystallite sizes, D of ZnO-MWCNTs was measured varies from 21 nm to 11 nm. The oat-like ZnO nanoflakes structure and the presence of MWCNTs were captured by field-emission scanning electron microscopy (FESEM) analysis. Transmission electron microscopy (TEM) analysis measured the inner (~6.81 nm) and outer (~28.31 nm) diameter of MWCNTs. The optimum concentration of 0.1 wt.% MWCNTs produced the highest photocurrent density, Jsc of 13.5 mA/cm2, open-circuit voltage, Voc of 0.149 V, fill factor, FF of 0.406 and power conversion efficiency, PCE of 0.817 %. Optimum doping of 0.1 wt.% MWCNTs generated short electron lifetime, τeff of 0.67 ms, low effective electron chemical diffusion coefficient, Deff of 9.5 x 10-8 cm2 s-1 and higher electron recombination rate, keff of 1497.48 s-1. The addition of MWCNTs has influenced the structural, morphological, photovoltaic and electron transport properties of ZnO-MWCNTs based DSSC.
Dielectric and Conduction Processes and Behaviours in Ni0.3Zn0.7Fe2O4
Authors: Mat Mohd Noor , Halimah M.K. , Wan Yusoff Wan Mohd Daud , Mansor H. , Nizam H. , Zainuddin Y. , Aiman T.I.T.M.
Published: March 2016

Dielectric relaxation and conductivity of Ni0.3Zn0.7Fe2O4 (NZF) were studied in the frequency range between 0.01 Hz to 3 MHz and temperature range within 313 K to 473 K. The sample was prepared by mixing Zinc Oxide, Nickel Oxide and Iron Oxide and sintered at 1573 K for 10 hours long. Dielectric properties were studied using Novo Control Dielectric Spectrometer. Dielectric relaxation and conductivity phenomena were discussed using an empirical model to key out the dielectric relaxation process. Analyze peak frequency relaxation process consist of four slopes to explain the dielectric relaxation process. The conductivity of the sample indicates an activated process and activation energy of dc conductivity is 0.44 ± 0.01 eV.
Optical, Thermal and Dielectric Studies of Silver-Silica Nanoparticles Synthesized via Sol-Gel Technique
Authors: Taib Taifunisyam , Mohamad Souad A. , bin Johan Mohd Rafie , Basirun Wan Jefrey , Ming Chin Kim , Cherng Chia Chang , Herng Tan Jia
Published: March 2016

Silver-silica nanocomposites (Ag-SiO2NCs) with various compositions were synthesized through sol-gel technique. The morphology, optical and thermal stability of the nanocomposite were investigated and was compared with pure sol-gel to determine the effects of the nanoparticles. Transmission electron microscopy (TEM) confirmed that SiO2 was encapsulated Ag with mean size of 30 nm. Uv-vis spectroscopy shows that the surface plasmon resonance (SPR) peak show Ag-SiO2 NCs were greatly reduce due to the SiO2 particles. The permittivity and refractive index were decreased as the composition of Ag was increased at composition of 60% silver. The real permittivity is negative along the visible region. The trend stability of Ag-SiO2NCs were increased with the increased amount of silver.
Effect of Sr Substitution in La-Ca-Mn-O Compound on Structural and Electrical Properties
Authors: Wan Jusoh Wan Nur Wathiq , Pah Lim Kean , Kechik M.M. Awang , Halim S.A. , Ng Siau Wei
Published: March 2016

Polycrystalline manganites compound of La0.67A0.33MnO3 (A= Sr, Ca) has prepared by conventional solid state reaction method. In this work, an effort has been made to study the influences of substitution with different alkaline earth in La-site. The structural of La0.67A0.33MnO3 was studied by X-ray diffraction patterns (XRD), XRD spectrums of La0.67Ca0.33MnO3 (LCMO) showed in orthorhombic structure (space group Pbnm) while La0.67Sr0.33MnO3 (LSMO) was in hexagonal structure (R-2c). The LCMO and LSMO bulks were investigated magnetically in view to understanding the ferromagnetic-paramagnetic (FM-PM) behaviors using vibrating sample magnetometer (VSM) at room temperature. LSMO bulk sample exhibited ferromagnetic with high in magnetization while LCMO bulk was in paramagnetic behaviors. The Curie temperature and metal-insulator transition temperature (Tp) were measured using AC Susceptibility (ACS) at temperature range 78 K- 300 K and four-point probe technique. The Tc for LCMO was 260 K, the curves coincide at temperatures above 240 K and become zero around the Curie critical temperature, where the FM-PM transition occurs and Tp for LCMO was reported around 250 K. Meanwhile, the Tc and Tp for LSMO were above 300 K. The difference in grain sizes of the microstructure images of LCMO and LSMO are might be due to the substitution of variance alkaline earth ions that differs in grain growth were observed using scanning electron microscopy (SEM). By replacing Sr2+ in La-Ca-MnO, the crystal structure transform from orthorhombic to hexagonal with highly symmetrical, thus the MnO6 octahedral are less distortion and the local spins are relatively more aligned. Therefore, electron hopping interaction at sub-orbital (3d:eg) increase, resulting the Tc and Tp are shifted to higher values
The Effect of Sintering Temperature on the Structural and Magnetic Properties of Ni-Mg Substituted CoFe2O4 Nanoparticles
Authors: Rosnan Rizuan Mohd , Othaman Zulkafli , Ati Ali A. , Hussin Rosli , Dabagh Shadab , Zare Samad
Published: March 2016

This study evaluates the structural and magnetic properties of Ni-Mg substituted Cobalt ferrite samples prepared through the co-precipitation method. The nominal compositions Co0.5Ni0.5−xMgx Fe2O4 in the range x = 0.1 have been synthesized and then was sintered at temperature at 700 and 1000°C in the furnace for 10 hour with a heating rate of 5°C/min. The prepared nanoferrites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and vibration sample magnetometer (VSM). XRD confirmed formation of single phase spinel ferrite with average crystalline size in the range of 27–33 nm. The lattice constant (a), cell volume (V) and X-ray density (ρx) are also calculated from XRD data. Lattice constant (a) decreases with an increase of sintering temperature. Further information about the structure and morphology of the nanoferrites was obtained from FESEM and results are in good agreement with XRD. Saturation magnetization showed increasing trend with sintering temperature from 700 to 1000°C.
Influence of Microstructural Evolution on the Magnetically Group Dominance in Polycrystalline Y3Fe5O12  Multi-Samples
Authors: Nazlan Rodziah , Hashim Mansor , Ibrahim Idza Riati , Abdullah Nor Hapishah , Mohd Idris Fadzidah , Ismail Ismayadi , Wan Ab Rahman Wan Norailiana
Published: March 2016

In present work, the effect of changing microstructure on magnetic properties which evolves in parallel, in particular from amorphous-to-crystalline development, in yttrium iron garnet was investigated. 9 toroidal samples of polycrystalline yttrium iron garnets were prepared by using the mechanical alloying technique and sintered at low to high sintering temperature for microstructure-dependent-magnetic evolutions. A brief, yet revealing characterization of the samples were carried out by using an X-ray Diffraction, Field Emission Scanning Electron Microscopy, Impedance Material Analyzer, LCR-meter and, Picoammeter. It is believed that microstructural features such as amorphous phase, grain boundary, secondary phase and intergranular pores contribute significant additional magnetic anisotropy and demagnetizing fields, thus affecting the initial permeability accordingly. A scrutinizing observation of the permeability component results show that they tend to fall into three groups of magnetic permeability according to degree of magnetic behaviour dominance. The Curie temperature remained relatively stable and unaffected by the evolution, thus confirming its intrinsic character of being dependent only on the crystal structure and compositional stoichiometry. The increased electrical resistivity while the microstructure was evolving is believed to strongly indicate improved phase purity and compositional stoichiometry.
Surface Passivation Effect of Hydrogen and Methyl on the Structural and Electronic Properties of Silicon Quantum Dots: Density Functional Calculation
Authors: Anas Muhammad Mus-'Ab Anas Mohd , Gopir Geri
Published: March 2016

We have carried out a series of DFT calculations to investigate changes on the structural and electronic properties of Silicon (Si) quantum dots as a function of surface passivation. In particular, we have study non-polar passivation effect of hydrogen (H) and methyl (CH3) at the surface of quantum dots. From geometry optimization result, we find that clusters with reconstructed surfaces a complete methyl passivation is possible and steric repulsion prevents full passivation of Si dots with unreconstructed surfaces. On the electronic properties point of view, it is noticed for small nanocrystals, the presence of mini-gaps are more pronounced which can limit the non-radiative relaxation of excitons. Obviously, methyl passivation weakly affects the band gap values of silicon quantum dots, while it substantially decreases the band gap and reduce mini-gap appearance compared to hydrogen passivation Si QDs. On the basis of our results we propose that methyl terminated quantum dots may be size selected taking advantage of the reduction on mini-gap and the localization of electron as a function of the cluster size.
Effect of Variation Sintering Temperature on Magnetic Permeability and Grain Sizes of Y3Fe5O12 via Mechanical Alloying Technique
Authors: Mohd Shahrani Nuraine Mariana , Azis Ra'ba'ah Syahidah , Hashim Mansor , Hassan Jumiah , Azmi Zakaria , Daud Noruzaman
Published: March 2016

This work will focus on the preparation of yttrium iron garnet (Y3Fe5O12, YIG) via mechanical alloying technique derive by steel waste product. The Fe2O3 powder derived from the steel waste purified by using magnetic and non-magnetic particles (MNM) and Curie temperature separation (CTS) technique. The purified powder was then oxidized in air at 500 °C for 9 hours in air. The Fe2O3 was mixed with Y2O3 using high energy ball milling for 9 hours. The mixed powder obtained was pressed and sintered at different temperature 500/600/700/800/900/1000/1100 °C. X-ray diffraction (XRD) shows the YIG is completely form at 1100 °C. The field emission scanning electron microscopy (FESEM) images shows the grain size increases as increase the sintering temperatures. The frequency dependence on the complex permeability, µ’ and magnetic loss, µ’’ in the frequency range 10 MHz to 1 GHz were measured in this study. The results showed that the highest μ΄ is 5.890 obtained from 1100 °C.
Characterization of Cu-Al2O3 and Ni-Al2O3 Nanocomposites Electrodeposited on Copper Substrate
Authors: Tey Eydar , Hashim Mansor , Ismail Ismayadi
Published: March 2016

In the present work, it was attempted to electrodeposit Cu-Al2O3 and Ni-Al2O3 metal matrix composite (MMC) coatings onto a copper substrate using a modified Watts bath containing dispersed nanosized Al2O3 with an average particle size of 50 nm. The prepared nanocomposite coatings were subjected to different tests to characterize their surface morphology, crystalline structure and mechanical properties. The microstructure and composition of the composite films were studied with Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) techniques. The use of nanoparticles could change the microstructure and morphology of the electrodeposits, depending on the metal matrix composites. The hardness and wear resistance tests were carried out on nanocomposite coating samples to investigate the mechanical properties. The co-deposited Al2O3 nanoparticles in the deposit increased the hardness and wear resistance, which were closely related with Al2O3 content in the nanocomposites. The hardness of the Ni-Al2O3 coating increased by about 26.3 % compared to pure copper plate due to the dispersion hardening effect. The hardness of the Cu-Al2O3 coating decreased by about 25.2 % as compared to pure copper plate due to the minimization of surface energy and the surface porosity of the coating. The wear resistance of the Ni-Al2O3 coating on the copper substrate was higher than that of Cu-Al2O3 as deduced from the lower mass loss of the former. The novelty of this project is the creation of very hard coating using a relatively low cost method.
Mechanochemical Synthesis of CNT/ZnO Hybrid Materials
Authors: Aziz Siti Sumaiyah Sheikh Abdul , Harun Nurhana Ilmira , Salleh Nunshaimah , Senawi S.A. , Azhan H. , Mohd Yusoff Siti Nor Hafiza , Mohd Amin Yusoff , Md Nor Roslan
Published: March 2016

A study on the synthesis of multiwalled carbon nanotubes (MWCNT) and zinc oxide (ZnO) hybrid materials using the mecahnochemical technique has been conducted. MWCNT was dispersed in sodium dodecyl sulfate (SDS) solution. ZnO was formed at milling time between 2 and 5 hours, where at 10 hours the XRD results showed only small peaks of ZnO. This suggests that at longer milling time, the ZnO crystals were either become amorphous or have reduced in sized so as not to be detected using XRD. ZnO has also been doped with Manganese (Mn) which have affected the crystal structure and surface morphology of the sample.Keywords:Doping, Manganese nitrate, Mechanochemical technique, Multiwalled carbon nanotubes (MWCNT), Surfactant method , Zinc Oxide (ZnO)
Review of Energy and Power of Supercapacitor Using Carbon Electrodes from Fibers of Oil Palm Fruit Bunches
Authors: Deraman Mohamad , Nor Najah Syahirah Mohd , Taer Erman , Yatim Baharudin , Awitdrus Awitdrus , Farma Rakhmawati , Basri Nur Hamizah , Othman Mohd Amir Radhi , Omar Ramli , Jasni Mohamad Redwani Mohd , Daik Rusli , Soltaninejad Sepideh , Suleman Mohd , Hegde Gurumurthy , Astimar Abdul Aziz
Published: March 2016

Energy and power capability of a supercapacitor is important because of its function to provide backup power or pulse current in electronic/electric products or systems. The choice of its electrode materials, typically such as carbon, metal oxide or conducting polymer determines the mechanism of its energy storage process. This short review focuses on the supercapacitors using porous carbon electrode prepared, respectively, from fibers of oil palm empty fruit bunches. The specific energy and specific power of these supercapacitors were analyzed to observe their trend of change with respect to the electrode preparation parameters affecting the porosity, structure, surface chemistry and electrical conductivity of electrodes, and thence influence the energy and power capability of a supercapacitor. This review found that the trend of change in specific energy and specific power was not in favor of the expectation that both the specific energy and specific power should be in increasing trend with a significant progress.
Effect of Eu Substitution in Low Density Bi (Pb)-2223 High Temperature Superconductors
Authors: Azhan H. , Azura C.M.N. , Azman K. , Senawi S.A. , Syuhaida I.N. , Robaiah M. , Rosli Mohd Mustaqim
Published: March 2016

High temperature superconductor ceramic of low density Bi1.6Pb0.4Sr2(Ca2-xEux)Cu3Oy both doped and non-doped, have been produced by the method of conventional solid state reaction synthesis. The effects of rare earth doping on the low density superconducting compound have been studied by considering Eu substitution at Ca site to stoichiometric of Bi (Pb)-2223 with x ranging from 0.000 to 0.2000. The experimental works in this study consist of direct-current (DC) electrical resistance-temperature and critical current density measurements for both electrical and superconducting properties, and powder X-ray diffraction (XRD) for phase analyses and lattice parameters while Field Emission Scanning Electron Microscopy (FESEM) for surface morphology. All the Eu-doped samples consist of both low-Tc Bi (Pb)-2212 and High-Tc Bi (Pb)-2223 phases. The substitution of Eu at the Ca site induced the decrease of volume fraction for the Bi (Pb)-2223 phase and the increase of the volume fraction for Bi (Pb)-2212 phase. Eu doping does not enhance the Tc zero but gradually decrease its value and become semiconducting at higher dopant concentration with x=0.200. From FESEM investigation, the grain size started to degrade from x=0.000 to x=0.0100 and form smaller plate-like grain which belong to Bi (Pb)-2212 phase and the grain particles are seem to be coagulated to form clusters for x=0.200.
Electrical and Structural Properties of Ca Substitution in High and Low Density Y(Ba1-xCax)2Cu3O7-δ Superconductor
Authors: Hashim Azhan , Norazidah Abd Wahab , Kasim Azman , Nazree A. , Syamsyir S. Akmal , Hidayah H.N. , Hawa J.S.
Published: March 2016

The effect of Ca substitution on the electrical and structural properties in high and low density Y(Ba1-xCax)2Cu3Oδ where x = 0.00, 0.10, 0.20 and 0.30 via solid state reaction method has been investigated. The electrical properties, elemental analysis, and structural identification were measured by the four-point probe technique, energy dispersive x-ray (EDX) and X-ray diffraction (XRD) respectively. The electrical properties such as critical temperature (Tc) and critical current density (Jc) were found to be strongly dependent in both high and low densities Y(Ba1-xCax)2Cu3O7-δ. These parameters were decreased monotonously with the increasing of Ca substitution. An obvious results of the Ca-doped samples can be seen in x = 0.20 where Tc zero of high density sample is 77 K, which is higher than that of the low density sample that occurred at 73 K. Meanwhile, Jc at 60 K for high density is 1.842 A/cm2 compared to 1.410 A/cm2 in low density sample. EDX analysis confirmed the existence of Ca in all doped samples. The crystallographic structure remained orthorhombic and the volume of unit cell increased towards further increased of Ca concentration.
Superconducting and Elastic Properties of PbBa2Y1-xCaxCu3O7+δ
Authors: Chong Tet Vui , Abd-Shukor Roslan
Published: March 2016

PbBa2Y1-xCaxCu3O7+δ (x = 0.00, 0.15, 0.20, 0.25 and 0.50) samples were prepared via solid state reaction. All samples except x = 0.50 exhibited various critical temperatures Tc. The X-ray diffraction patterns show all samples were in mixed phase. Longitudinal and shear ultrasonic velocities in these samples were measured using the pulsed-echo-overlap method with frequency 5-10 MHz in the temperature range 80-300 K. There are no obvious elastic anomalies which are usually observed in most high temperature superconductors were observed in any of the samples in both longitudinal and shear modes. Furthermore, there is no significant variation in the percentage of velocity change in both longitudinal and shear modes with the different content of x doped for all samples.
Radio-Frequency Sputtering Growth of Indium Nitride Thin Film on Flexible Substrate
Authors: Lee Zhi Yin , binti Osman Siti Aisyah , Fong Chee Yong , Ng Sha Shiong
Published: March 2016

The study signifies the radio-frequency (RF) sputtering growth and characterizations of indium nitride (InN) thin films deposited on flexible substrates. A three-inch diameter indium (In) sputtering target with purity of 99.999% was used. The deposition was carried out at room temperature and with substrate temperature of 200 °C. The surface morphologies, structural and optical properties of the deposited thin films were examined by using field-emission scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction as well as Fourier transform infrared spectroscopy. All the results revealed that InN thin films have been successfully deposited on the flexible substrates in the gas mixture ambient of argon and nitrogen.
Enhancement of Tensile Properties of Surface Treated Oil Palm Mesocarp Fiber/Poly(Butylene Succinate) Biocomposite by (3-Aminopropyl)Trimethoxysilane
Authors: Then Yoon Yee , Azowa Ibrahim Nor , Zainuddin Norhazlin , Chieng Buong Woei , Eng Chern Chiet , Ariffin Hidayah , Yunus Wan MD Zin Wan
Published: March 2016

The issue related to relatively poor interfacial adhesion between hydrophilic natural fiber and hydrophobic thermoplastic remain as an obstacle in natural fiber/thermoplastic biocomposites. Consequently, surface treatment of fiber is of important to impart adhesion. The present work used consecutive superheated steam-alkali treatment to treat the oil palm mesocarp fiber (OPMF) prior to biocomposite fabrication. The biocomposites made up of 70 wt% treated OPMF and 30 wt% poly (butylene succinate) (PBS) were prepared by melt blending technique in a Brabender internal mixer followed by hot-press moulding into 1 mm sheets. A silane coupling agent of (3-aminopropyl) trimethoxysilane (APTMS) was also added to the biocomposite during the process of compounding to promote interfacial adhesion and enhance the properties of biocomposites. The results showed that the biocomposite containing 2 wt% APTMS showed maximum enhancement in tensile strength (89%), tensile modulus (812%) and elongation at break (52%) in comparison to that of untreated OPMF/PBS biocomposite. The SEM observation of the tensile fracture surface revealed that APTMS improved the interfacial adhesion between treated OPMF and PBS. It can be deduced that the presence of APTMS can improve the adhesion between hydrophilic fiber and hydrophobic thermoplastic, and thus increased the tensile properties of the biocomposite.
Magnetic Properties of Sm3+ Doped Zinc Phosphate Glass Containing Nickel Oxide Nanoparticles
Authors: Mohamad Azmi Siti Amlah , Sahar M.R.
Published: March 2016

Nickel nanoparticles are incorporated in Sm3+ doped zinc phosphate glass having a composition of 40ZnO-(58-x)P2O5-1Sm2O3-xNiO, with x = 0.0 and 2.0 mol% prepared by melt quenching technique. Sample characterizations are made by means of X-ray diffraction, transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). X-ray diffraction shows that the glass is in amorphous state. The transmission electron microscopic (TEM) image reveals the existence of Nickel nanoparticles having a particles size in the range of 5.5 – 21.8 nm. The magnetization M(H) curve reveals that the glass displays an anomalous hysteresis behavior at room temperature. It is observed that the initial curve of magnetization lies positively as a function of magnetic field under 1000 H (O.e).
Luminescence Features of Silver Nanoparticles Sensitized Samarium Doped Boro-Zinc Tellurite Glasses
Authors: Ghoshal Sib Krishna , Shafie@Haron Masni , Sahar M.R.
Published: March 2016

Spectral features modification of rare earth (RE) doped tellurite glasses via controlled manipulation of metallic nanoparticles (NPs) is the current challenge in achieving enhanced lasing action. Triggering the localized surface plasmon resonance (SPR) of NPs in the glass generates tremendous applied interests especially in solid state lasers and nanophotonics. Despite several promising features of RE doped zinc-boro-tellurite glass, the low absorption and emission cross-section of RE ions prohibit them from fabricating efficient lasers. This drawback needed to overcome and significant enhancement of spectral features is required. Co-doping by rare earths and/or embedding metallic NPs (acts as sensitizer) are demonstrated to be the alternative route to surmount such shortcomings. Series of glass samples with composition 74TeO2–15B2O3–10ZnO– 1Sm2O3 – (x)Ag, where 0 ≤ x ≤ 0.1 mol% (in excess) are prepared using melt quenching method and the impacts of silver (Ag) NPs concentrations in altering their photoluminescence properties are inspected. The XRD spectra confirmed the amorphous nature of prepared glasses and the presence of Ag NPs are evidenced in EDX spectra. TEM micrographs revealed the distribution of Ag NPs with average size 7.2 nm. Absorption spectra revealed eight bands which most intense between 6F11/2 and 6F1/2. Photoluminescence spectra exhibited three prominent peaks corresponding to the transition from the excited state 4G5/2 to 6H5/2, 6H7/2, and 6H9/2 states, respectively. Our observation may be useful for the development of tellurite glass based nanophotonic devices.
Об отображениях, близких к субаддитивным
Authors: Shul'man Ekaterina Viktorovna
Published: March 2016

В работе устанавливаются некоторые результаты об устойчивости в духе Улама-Хайерса для классов отображений из групп в решeтки, удовлетворяющих условию субаддитивности:
$$
F(gh) \subset F(g)\cup F(h) \quad для всех g,h \in G.
$$
Chemical characteristics and causes of airborne particulate pollution in warm seasons in Wuhan, central China
Authors: Lyu X. P. , Chen N. , Guo H. , Zeng L. W. , Zhang W. H. , Shen F. , Quan J. H. , Wang N.
Published: March 2016

Abstract. Continuous measurements of airborne particles and their chemical compositions were conducted in May, June, October and November 2014 at an urban site in Wuhan, Central China. The results indicated that the particle concentrations stayed at a relatively high level in Wuhan, with the averages of 135.1 ± 4.4 (mean ± 95 % interval) and 118.9 ± 3.7 μg/m3 for PM10, and 81.2 ± 2.6 and 85.3 ± 2.6 μg/m3 for PM2.5 in summer and autumn, respectively. Moreover, PM2.5 frequently exceeded the National Standard Level II (i.e., daily average of 75 μg/m3), and six PM2.5 episodes were captured during the sampling campaign. The composition analysis found that secondary inorganic ions and carbonaceous aerosols dominated the constituents of PM2.5. It is noteworthy that potassium (K) (2060.7 ± 82.3 ng/m3, 47.0 ± 2.2 %) was the most abundant element, implying the biomass burning in/around Wuhan. During the episodes, carbonaceous aerosols increased significantly, a signature of combustion activities as well. The source apportionment confirmed that biomass burning was the main cause of PM2.5 episodes except for case 2, with the contribution ranging from 48.0 ± 1.0 % in case 5 to 70.1 ± 0.5 % in case 3. Fugitive dust and oil refinery/usage were the main contributors to PM2.5 in case 2. In addition to biomass burning, the contribution of oil refinery/usage also increased in case 5. Furthermore, the mass and proportion of NO3− peaked in case 6. It was found that the high levels of NOx and NH3, and low temperature in case 6 were responsible for the increment of NO3−. We also found that SOC formation was dominated by the aromatics and isoprene in autumn, and the contribution of aromatics increased during the episodes.
Modeling spatiotemporal dynamics of global wetlands: comprehensive evaluation of a new sub-grid TOPMODEL parameterization and uncertainties
Authors: Zhang Zhen , Zimmermann Niklaus E. , Kaplan Jed O. , Poulter Benjamin
Published: March 2016

Abstract. Simulations of the spatiotemporal dynamics of wetlands are key to understanding the role of wetland biogeochemistry under past and future climate. Hydrologic inundation models, such as the TOPography-based hydrological model (TOPMODEL), are based on a fundamental parameter known as the compound topographic index (CTI) and offer a computationally cost-efficient approach to simulate wetland dynamics at global scales. However, there remains a large discrepancy in the implementations of TOPMODEL in land-surface models (LSMs) and thus their performance against observations. This study describes new improvements to TOPMODEL implementation and estimates of global wetland dynamics using the LPJ-wsl (Lund–Potsdam–Jena Wald Schnee und Landschaft version) Dynamic Global Vegetation Model (DGVM) and quantifies uncertainties by comparing three digital elevation model (DEM) products (HYDRO1k, GMTED, and HydroSHEDS) at different spatial resolution and accuracy on simulated inundation dynamics. In addition, we found that calibrating TOPMODEL with a benchmark wetland data set can help to successfully delineate the seasonal and interannual variation of wetlands, as well as improve the spatial distribution of wetlands to be consistent with inventories. The HydroSHEDS DEM, using a river-basin scheme for aggregating the CTI, shows the best accuracy for capturing the spatiotemporal dynamics of wetlands among the three DEM products. The estimate of global wetland potential/maximum is  ∼ 10.3 Mkm2 (106 km2), with a mean annual maximum of  ∼ 5.17 Mkm2 for 1980–2010. When integrated with wetland methane emission submodule, the uncertainty of global annual CH4 emissions from topography inputs is estimated to be 29.0 Tg yr−1. This study demonstrates the feasibility of TOPMODEL to capture spatial heterogeneity of inundation at a large scale and highlights the significance of correcting maximum wetland extent to improve modeling of interannual variations in wetland area. It additionally highlights the importance of an adequate investigation of topographic indices for simulating global wetlands and shows the opportunity to converge wetland estimates across LSMs by identifying the uncertainty associated with existing wetland products.
An experimental seasonal hydrological forecasting system over the Yellow River basin – Part II: The added value from climate forecast models
Authors: Yuan Xing
Published: March 2016

Abstract. This is the second paper of a two part series on introducing an experimental seasonal hydrological forecasting system over the Yellow River basin in northern China. While the natural hydrological predictability in terms of initial hydrological conditions (ICs) is investigated in a companion paper, the added value from eight North American Multimodel Ensemble (NMME) climate forecast models with a grand ensemble of 99 members is assessed in this paper, with an implicit consideration of human-induced uncertainty in the hydrological models through a post-processing procedure. The forecast skill in terms of Anomaly Correlation (AC) for 2-m air temperature and precipitation does not necessarily decrease over leads, but is dependent on the target month due to a strong seasonality for the climate over the Yellow River basin. As there is more diversity in the model performance for the temperature forecasts than the precipitation forecasts, the grand NMME ensemble mean forecast has consistently higher skill than the best single model out to six months for the temperature, but up to two months for the precipitation. The NMME climate predictions are downscaled to drive the Variable Infiltration Capacity (VIC) land surface hydrological model and a global routing model regionalized over the Yellow River basin to produce forecasts of soil moisture, runoff and streamflow. And the NMME/VIC forecasts are compared with the Ensemble Streamflow Prediction method (ESP/VIC) through 6-month hindcast experiments for each calendar month during 1982–2010. As verified by the VIC offline simulations, the NMME/VIC is comparable to the ESP/VIC for the soil moisture forecasts, and the former has higher skill than the latter only for the forecasts at long leads and for those initialized in the rainy season. The forecast skill for runoff is lower for both forecast approaches, but the added value from NMME/VIC is more obvious, with an increase of the average AC by 0.08–0.2. To compare with the observed streamflow, both the hindcasts from NMME/VIC and ESP/VIC are post-processed through a linear regression model fitted by using VIC offline simulated streamflow. The post-processed NMME/VIC reduces the root mean squared error (RMSE) from the post-processed ESP/VIC by 5–15 %. And the reduction occurs mostly during the transition from wet to dry seasons. With the consideration of the uncertainty in the hydrological models, the added value from climate forecast models is decreased especially at short leads, suggesting the necessity of improving the large-scale hydrological models in human intervened river basins.
Repeated electromagnetic induction measurements for mapping soil moisture at the field scale: validation with data from a wireless soil moisture monitoring network
Authors: Martini Edoardo , Werban Ulrike , Zacharias Steffen , Pohle Marco , Dietrich Peter , Wollschläger Ute
Published: March 2016

Abstract. Electromagnetic induction (EMI) measurements are widely used for soil mapping, as they allow fast and relatively low-cost surveys of soil apparent electrical conductivity (ECa). Although the use of non-invasive EMI for imaging spatial soil properties is very attractive, the dependence of ECa on several factors challenges any interpretation with respect to individual soil properties or states such as soil moisture (θ). The major aim of this study was to further investigate the potential of repeated EMI measurements to map θ, with particular focus on the temporal variability of the spatial patterns of ECa and θ. To this end, we compared repeated EMI measurements with high-resolution θ data from a wireless soil moisture and soil temperature monitoring network for an extensively managed hillslope area for which soil properties and θ dynamics are known. For the investigated site, i) ECa showed small temporal variations whereas θ varied from very dry to almost saturation; ii) temporal changes of the spatial pattern of ECa differed from those of the spatial pattern of θ; and iii) the ECa-θ relationship varied with time. Results suggest that i) stable soil properties are the major control on ECa measured with EMI, and ii) for soils with low clay content, the electrical conductivity of the soil solution rather than θ is likely to be the dynamic factor controlling temporal variations of ECa. Further, our study provides the opportunity to discuss the complex interplay between factors controlling ECa and θ, and the use of EMI-based ECa data with respect to hydrological applications.
Vessel protection, van zorgplicht naar zelfverdediging
Authors: Warnar Henk
Published: March 2016

Vessel protection, from state’s obligation to provide security to self protection

This article demonstrates the influence of intellectual debate in policy paradigm changes. In response to piracy around the Horn of Africa, Dutch naval forces have participated in NATO and EU counter piracy operations since 2008. Although successful, also self protection measures by the merchant ships are required to provide security to individual ships. Since 2008 Dutch ship owners have advocated to amend legislation to allow private armed security teams (PAST) for individual protection, similar to policies by most foreign countries. Because of sensitivities concerning the private use of arms, policymakers, politicians, stakeholders and advisors have circumvented the issue. Instead of addressing the question of self defense, the paradigm of state monopoly for violence and the state’s obligation to provide security, made individual protection by embarked military teams to develop as a governmental service at levels that turned out to be unachievable for the armed forces. This policy caused several types of friction. Currently, the only acceptable solution seems to be to allow PAST and legislation is being prepared accordingly. A successful paradigm change however can only be achieved if an adequate new paradigm is constructed by intellectual debate. (Hall, Visser & Hemerijck) So far this debate has been too limited in scope. Debate has been state centric and focused on legal views and regulation. To resolve friction, additional analysis of differing roles by the state and individual entrepreneurs is required. Such analysis argues that the state severely reduces individual protection and politicians decide on the fundamental question of self defense by ships at the high seas.
The American Flag
Authors: King Alessandra
Published: March 2016

Students are given an activity in which they analyze the American flag, with an eye to its proportions. Solutions are online.
Build those numbers
Authors: Camaligan Brenda
Published: March 2016

Students are challenged to use numbers rolled on three dice to write expressions for values 1–12, using as few rolls as possible. Postscript items are designed as rich grab-and-go resources that teachers can quickly incorporate into their classroom repertoire with little effort and maximum impact.
WNT-C59, a Small-Molecule WNT Inhibitor, Efficiently Induces Anterior Cortex That Includes Cortical Motor Neurons From Human Pluripotent Stem Cells
Authors: Motono Makoto , Ioroi Yoshihiko , Ogura Takenori , Takahashi Jun
Published: March 2016

The recapitulation of human neural development in a controlled, defined manner from pluripotent stem cells (PSCs) has considerable potential for studies of human neural development, circuit formation and function, and the construction of in vitro models of neurological diseases. The inhibition of Wnt signaling, often by the recombinant protein DKK1, is important for the induction of cortical neurons. Here, we report a novel differentiation method using a small-molecule WNT inhibitor, WNT-C59 (C59), to efficiently induce human anterior cortex. We compared two types of small molecules, C59 and XAV939 (XAV), as substitutes for DKK1 to induce cortical neurons from PSCs in serum-free embryoid body-like aggregate culture. DKK1 and XAV inhibited only the canonical pathway of Wnt signaling, whereas C59 inhibited both the canonical and noncanonical pathways. C59 efficiently induced CTIP2+/COUP-TF1− cells, which are characteristic of the cells found in the anterior cortex. In addition, when grafted into the cortex of adult mice, the C59-induced cells showed abundant axonal fiber extension toward the spinal cord. These results raise the possibility of C59 contributing to cell replacement therapy for motor neuron diseases or insults.

Significance

For a cell therapy against damaged corticospinal tract caused by neurodegenerative diseases or insults, cortical motor neurons are needed. Currently, their induction from pluripotent stem cells is considered very promising; however, an efficient protocol to induce motor neurons is not available. For efficient induction of anterior cortex, where motor neurons are located, various WNT inhibitors were investigated. It was found that one of them could induce anterior cortical cells efficiently. In addition, when grafted into the cortex of adult mice, the induced cells showed more abundant axonal fiber extension toward spinal cord. These results raise the possibility that this inhibitor contributes to a cell-replacement therapy for motor neuron diseases or insults.
La hoja transfronteriza. El consumo de coca en las faenas mineras salitreras en el Norte Grande de Chile (1900-1930)
Authors: González Miranda Sergio
Published: March 2016

Bolivian workers have crossed the Andes and participated in the nitrate-mining projects from the beginning of the cycle of expansion of that industry in the 19th century until its definitive ending with the crisis of 1930. Along with the arrival of these workers in the towns and camps of Tarapacá and Antofagasta, came a variety of goods that formed an essential part of their diet, including coca leaves. Although the consumption of this product is associated with high-altitude mining and underground mining, this article studies the importance it had in desert and open-pit mining. It also analyzes the commerce of coca in the local stores known as pulperías, and the opinion of public officials regarding the social and labor impact of this cross-border leaf. A historiographical study was done of press archives and official documents located in Chile and Bolivia, to contrast the hypotheses on the subject, leading to conclude that the consumption of coca was generalized among workers of almost all types in the nitrate-mining industry. With respect to nationalities, the consumption of coca was not limited exclusively to Bolivians, but was common among Peruvian and Chilean workers as well.
Representaciones del intelectual. El suplemento El Nuevo Tiempo Literario en Colombia y su relación con la cultura europea en la primera mitad del siglo XX
Authors: Bedoya Sánchez Gustavo Adolfo
Published: March 2016

This article explores the diverse images that the staff of the Colombian literary supplement El Nuevo Tiempo Literario presented of the stereotype of “intellectual” during the first half of the 20th century. It analyzes said representations through the study and comparison of emblematic European figures and the analysis of their ideas in important historical moments such as the Dreyfus Case and the Great War, for example. The conclusion is that the self-representations of the supplement’s collaborators made it possible to distinguish the differences and similarities between writing, thinking, and “acting,” i.e., between being literati, literary critics, and intellectuals committed to political action.
Experimental study on interface region of two-dimensional Si layers by forming gas annealing
Authors: Mizuno Tomohisa , Suzuki Yuhya , Kikuchi Reika , Suzuki Ayaka , Inoue Ryohsuke , Yamanaka Masahiro , Yokoyama Miki , Nagamine Yoshiki , Aoki Takashi , Maeda Tatsuro
Published: March 2016

We experimentally studied the SiO2/Si and Si/buried oxide (BOX) interface regions of a two-dimensional (2D) Si layer, by forming gas annealing (FGA). A photoluminescence (PL) result measured at various lattice temperature, T
L, values shows that the PL intensity I
PL of the 2D-Si layer rapidly increases and then saturates with increasing FGA temperature, T
A, and time, t
A. I
PL also increases with decreasing T
L. A one-dimensional (1D) Schroedinger equation simulator indicates that some of the electrons in the 2D-Si layer generated by a PL excitation laser are quantum–mechanically transmitted into Si interface regions. Actually, we experimentally confirmed that the PL spectra of the 2D-Si layer can be fitted by the PL emission from two regions with different PL peak photon energy values, E
PH, which consist of a typical 2D-Si and the interface regions of both the surface SiO2/Si and Si/BOX. Thus, this forming gas dependence is probably attributable to the improved lifetime τ of electrons in the surface interface region, because the Si surface is terminated by H atoms. Moreover, the E
PH of the interface region is higher than that of the 2D-Si layer, because of the graded increased bandgap in the interface regions. However, the E
PH of 2D-Si is independent of both T
A and T
L, and this T
L independence does not agree with that of a 3D-Si layer. Consequently, we experimentally verified the larger impact of the Si interface on the performance of 2D-Si layer.
Electrical characteristics of N-polar

p-type GaN Schottky contacts
Authors: Aoki Toshichika , Tanikawa Tomoyuki , Katayama Ryuji , Matsuoka Takashi , Shiojima Kenji
Published: March 2016

The electrical characteristics of Ni/N-polar p-GaN Schottky contacts were investigated in comparison with those of Ga-polar contacts. The Schottky barrier heights were obtained to be 0.91, 1.24, and 1.30 eV from the current–voltage (I–V), capacitance–voltage, and photoresponse results, respectively. These values of the N-polar samples were more than 1 eV lower than those of the Ga-polar samples. Hence, it was suggested that a Ni contact on N-polar p-GaN has a possible advantage in forming better ohmic electrodes. In addition, we also found that no memory effect, which was caused by the charge and discharge of surface defects [Ga vacancies (VGa)], was observed in the I–V characteristics, and no single peak of VGa was observed in the high-temperature isothermal capacitance transient spectroscopy spectrum. Therefore, it is suggested that the topmost N atomic layer can suppress the Ga out-diffusion.
Effects of nitridation for SiO2/SiC interface on defect properties near the conduction band edge
Authors: Takeuchi Wakana , Yamamoto Kensaku , Taoka Noriyuki , Sakashita Mitsuo , Kanemura Takashi , Nakatsuka Osamu , Zaima Shigeaki
Published: March 2016

We have investigated the effects of NO annealing on the electrical properties of a SiO2/4H-SiC interface. The electrical properties of the NO-annealed sample are different from those of the wet-annealed sample. NO or wet annealing generates positive or negative charges, respectively, in the insulator. The interface trap density (D
it) near the conduction band edge (E
c − 0.1 eV, where E
c is the conduction band edge) increases with NO annealing. In contrast, the D
it of the NO-annealed sample at around E
c − 0.2 eV is lower than that of the wet-annealed sample. The interface state near the conduction band edge in the NO-annealed sample is identified to be of the donor type. Thus, it is considered that the higher D
it near the conduction band edge and/or Coulomb scattering due to positive charges causes a decrease in the n-channel mobility in the nitrided SiO2/SiC interface by NO annealing.
Laparoscopic Roux en‐Y Gastric Bypass Using a Modified Retrocolic–Supracolic Approach: Outcomes from 300 Patients
Authors: Al‐Khyatt Waleed , Bull Charles A. , Awad Sherif , Ahmed Javed
Published: March 2016

Background

Laparoscopic Roux en‐Y gastric bypass (LRYGB) achieves sustained long‐term weight loss and reduced mortality in morbidly obese patients. It is routinely performed using an ante‐ or retrocolic approach with the jejuno‐jejunostomy constructed in the infracolic compartment. We have modified the standard technique of performing LRYGB by constructing both anastomoses in the supracolic compartment. This study describes the outcomes of consecutive primary LRYGB performed using this novel retrocolic–supracolic approach.

Methods

Data were prospectively collected on consecutive primary LRYGB performed in a tertiary‐referral Bariatric Centre in the United Kingdom from September 2009 to March 2013. Data included demographics, operative outcomes (duration of surgery, postoperative anastomotic leak/bleeding/reoperations), development of strictures, length of stay, excess weight loss (EWL) and resolution of diabetes mellitus.

Results

Hand‐sewn LRYGB was successfully performed using the retrocolic–supracolic approach in 300 of 307 (98 %) consecutive patients (72 % female). Median (IQR) age, weight and baseline body mass index were 49 (41–56) years, 146 (134–163) kg and 52.9 (48.8–57.2) kg/m2, respectively. There were 4 (1.3 %) anastomotic leaks and 8 (2.6 %) postoperative bleeds. The 30‐day reoperation rate was 1.6 %. Median (IQR) hospital stay was 2 (2–2) days. Postoperative dysphagia requiring endoscopic balloon dilatation occurred in 19 (6.3 %) patients. Mean ± SD 12‐month EWL was 69.9 ± 19.0 %. Within the follow‐up period, 81 % of patients with type II diabetes mellitus achieved remission and 19 % reduced dosage of diabetes medication.

Conclusions

LRYGB performed using the retrocolic–supracolic approach was safe, feasible, technically advantageous and resulted in clinical outcomes akin to the standard infracolic approach.