bluuebunny/crossref_metadata_2025 huggingface dataset:
Solvent Controlled Synthesis of Tin Oxide Nanocatalysts and their Applications in Photodegradation of Environmental Hazardous Materials
Authors: Muneer Iqra , Farrukh Muhammad Akhyar , Shaghraf Shaghraf , Khaleeq-Ur-Rahman Muhammad , Umar Akrajas Ali , Adnan Rohana
Published: May 2013

Solvent controlled synthesis of tin oxide nanocatalysts were prepared via the hydrothermal method. To study the effect of solvent on the particle size of tin oxide and their catalytic efficiency on photodegradation of environmental hazardous materials, the synthesis was carried out at different concentrations of solvent (isoamyl alcohol) keeping all other reaction conditions constant. The nanoparticles were characterized by FourierTransmission Infrared Spectroscopy, Scanning Electron Microscopy, Transmission Electron Microscopy, X-ray Diffraction and Thermogravimetric analysis. Prepared nanoparticles were applied as nanocatalyst under UV-visible light for the photodegradation of methyl green,which is an abundant organic pollutant of industrial waste water. Photodegradation activities of the nanocatalysts were measured in three different ways, i. pseudo first order rate constant, “k”. ii. percentage degradationand iii. degradation rate. Effect of solvent was quantitatively explained in term of double sphere model of ion-ion interaction. Degradation of pollutants was also monitored by High Performance Liquid Chromatography.
The Effect of Cu Concentration on TiO2 Nanotubes for Low Concentration of Pb(II) Removal
Authors: Zaki Syazwani Mohd , Sreekantan Srimala
Published: May 2013

Lead (Pb) has been recognized to be acutely toxic to human beings and studies have shown that young children, infants and pregnant women are particularly at risk to unsafe Pb (II) level. Generally, high level of Pb(II) can be removed by using alginate beads. However, at low level, it is not possible to be removed by alginate. For that reason, low concentration (10 ppm) of Pb(II) removal by photocatalytic activity is explored in this work. Cu loaded TiO₂ nanotube was prepared by wet impregnation with different Cu concentration. The initial concentration of Cu involved were 0.01 M, 0.06 M and 0.1 M. For heavy metal removal, the initial concentration of Pb(II) solution used was 10 ppm. The remnant concentration of Pb(II) solution after irradiated under ultraviolet(UV) light was determined by using Atomic Absorption Spectroscopy (AAS). It was observed that the optimal condition of Cu loaded nanotube was at 0.01 M and it exhibited highest removal of Pb(II) with 50%. However, at high Cu concentration(> 0.06 M), it declined the performance of TiO₂ nanotubes for Pb(II) removal. The removal of Pb(II) obtained at 0.06 M and 0.01M was only 23.3% and 17.1%.
Molybdenum Complex as Potential Photosensitiser for Direct Water Splitting
Authors: Wun Fui Mark Lee , Pui Law Kung , Heng Lee Yook , Kassim Mohamad Bin
Published: May 2013

Mononuclearmolybdenum complex with the general formula [MoTp*(NO)I(X)], where Tp* =tris(3,5-dimethylpyrazolyl)hidroborate and X =1,4-bis(pyridin-4-ylethynyl)benzene) was found to exhibit the required chemical and physical properties as a photosensitiser in photoelectrochemical cell. The complex was structurally characterised by infrared, UV-Vis and electrochemical analysis. TiO2 electrode films were prepared by paste technique and characterised by SEM and XRD. Photoelectrochemical properties of [MoTp*(NO)I(X)]-sensitisedTiO2 photoelectrode were carried out in 1.0 M NaOH electrolyte with a SCE reference electrode and a platinum counter electrode. The [MoTp*(NO)I(X)]-sensitised TiO2 photoelectrode showed positive photoinduced current compared to unsensitised TiO2 photoelectrode.
Fabrication and Characterization of Pb1-xYbxSe0.2Te0.8 Based Alloy Thin Films Thermoelectric Generators Grown Using Thermal Evaporation Method
Authors: Hmood Arshad , Kadhim Arej , Haslan Abu Hassan
Published: May 2013

In the current work p-Pb0.925Yb0.075Te:Te and n-Pb0.925Yb0.075Se0.2Te0.8 powders synthesized by solid-state microwave route were used to fabricating thermally evaporated thin films. The micro-thermoelectric devices were composedof 20-pairs and 10-pairs p-Pb0.925Yb0.075Te:Te and n-Pb0.925Yb0.075Se0.2Te0.8 thin films on glass substrates. Overall size of the thin films thermoelectric generators which consist of 20-pairs and 10-pairs of legs connected by aluminumelectrodes were 23 mm×20 mm and 12 mm×10 mm, respectively. The 20-pairs p–n thermocouples in series device generated output maximum open-circuit voltage of 275.3 mV and a maximum output power up to 54.4 nW at temperature difference ∆T= 162 K, and 109.4 mV and 16.7 nW at ∆T=162 K, for 10-pairs, respectively.
Properties of ZnO Rod-Like Structures Due to Collapse of Bubble Implosion Process
Authors: Johan Ooi Mahayatun Dayana , Azlan Abdul Aziz , Abdullah Mat Johar
Published: May 2013

In this work, a chemically grown ZnO rod – like structure is produced via precipitation and post – sonication treatment based on the hydrolysis of zinc iodide (ZnI2) and diethanolamine (DEA). ZnO rod – like structures with aspect ratio of 3 to 4(diameter of 235 nm and 800 nm in length) was observed from the TEM micrograph.The as-synthesized ZnO wurtzite structure was compared to sample without ultrasonic irradiation treatment to study the effect of bubble implosion on the formation of the particle. In contrast to particles treated with ultrasonic irradiation, micron sized and agglomerated particles were observed in sample without the treatment. The mechanism related to acoustic cavitations and the formation of rod – like structure is explained. The XRD results show polycrystalline structure on both samples. The optical property of ZnO was evaluated using room temperature UV - Visible absorption spectroscopy. The result showed an absorption peak at 381 nm in wavelength.
Preparation and Thermal Stability Characterization of Copper Tin Selenide Semiconductor Nanoparticles
Authors: Ying Chyi Liew Josephine , Talib Zainal Abidin , Wan Mahmood Mat Yunus , Zainal Zulkarnain
Published: May 2013

Copper tin selenide (Cu2SnSe3) nanoparticle powders were successfully synthesized via chemical precipitation method at room temperature. Elemental composition analysis determined byenergy dispersive X-ray confirmed that the Cu2SnSe3 nanoparticles were successfully formed. Field emission scanning electron and transmission electron micrograph showed the presence of homogeneous distribution of the small spherical nanoparticles in the Cu2SnSe3 powders. The thermal stability of the Cu2SnSe3 structure has been investigated by X-ray diffraction at temperatures ranging from 100 to 523 K. Differential scanning calorimetry and thermogravimetric analysis have been conducted to evaluate the thermal stability and it is found that the maximum temperature of the Cu2SnSe3 nanoparticles can withstand until 600 K. The results show that Cu2SnSe3 nanoparticles exhibited a stable structure at temperature range of 100 – 523 K.
Thermal Conductivity of Nanofluids
Authors: Sobti Amit , Wanchoo R.K.
Published: May 2013

Enhanced thermal conductivity of nanofluids compared to that of the base fluid has received attention of many researchers in the last one decade. Experimental data on thermal conductivity of nanofluids using varied nanoparticles in the size range 10-100 nm have been reported. However, there is lot of variance in the data and needs critical analysis. Many models have been proposed by various research groups for predicting the thermal conductivity of nanofluids. Due to complexity of various parameters involved (size, % volume fraction, specific surface area and the type of nano particles, pH of nano fluid, thermal conductivity and viscosity of base fluid) no single model can be used for predicting the thermal conductivity of nanofluids. Inconsistent and conflicting results are reported on the enhanced thermal conductivity of nanofluids. Further, insufficient understanding and inconclusive mechanism behind enhanced thermal conductivity requires further attempt to work in this field. This article critically reviews the available literature on thermal conductivity of nanofluids.
Stability of Nanofluids
Authors: Setia Hema , Gupta Ritu , Wanchoo R.K.
Published: May 2013

It has long been established that a suspension of nanosized solid particles in liquids provide useful advantages in industrial heat transfer fluid systems. Numerous investigations on nanofluids show a significant enhancement in thermal conductivity over the base fluid in which these nanoparticles are dispersed. However, the stability of the suspension is critical in the development and application of these new kind of heat transfer fluids. Rather, high discrepancy in the published data for the same nanoparticles on the physical and thermal characteristics of nanofluids is primarily due to different methods adopted by different researchers to obtain stable nanofluids. Sedimentation and agglomeration of nanoparticles in nanofluids and their dispersion stability has not been well addressed in the literature. Hence, there is a need to establish a standard method of preparation of these nanofluids so as to obtain a unified data which can eventually be utilized for the application of nanofluids. This chapter focuses on the stability of nanofluids prepared via two step process. Different parameters that affect the stability of nanofluids have been discussed. Different techniques that have been used for the evaluation of the stability characteristics of nanofluids have been elucidated.
Vapour Grown Carbon Fibre Reinforced Poly(Propylene) Filament
Authors: Chatterjee Arobindo
Published: May 2013

Polypropylene filament incorporating carbon nanofibre has been spun using conventional fibre processing route. Nanocomposite filament with very high dynamic modulus of 29 GPa and tenacity of 770 MPa could be obtained at 1% loading of nanofibres. The Nanocomposite filament exhibits higher thermal stability. Influence of carbon nanofibres on the morphology, mechanical and thermal properties of the nanocomposite filament have been studied.
Enhancement in Photocatalytic Activity of Nano-TiO2 Photocatalyst by Carbon Doping
Authors: Toor Amrit Pal , Yadav Neha , Wanchoo R.K.
Published: May 2013

The carbon doped TiO2 nanoparticles with different amount of carbon content were prepared using starch as the carbon source. The physical properties of the as-prepared catalyst were determined using X-ray diffraction, transmission electron microscopy and UV-vis diffuse reflectance spectroscopy. The results showed that carbon was successfully doped into TiO2 and the optical response of TiO2 was shifted from UV to the visible light region. The photocatalytic activity of these catalysts was evaluated by the degradation of phenol under UV and visible light irradiation. C-doped TiO2 nanocomposites showed better photocatalytic activity than the undoped TiO2 nanoparticles. The degradation rate of phenol on C-doped TiO2 was higher than those of pure TiO2 under visible light. As the results, C-doped TiO2 possessed better absorption ability of visible light. The kinetic studies revealed that the degradation of phenol follows pseudo first order reaction relationship.
Biopolymer Stabilized Iron Sulphide Nanoparticles for Removal of Acid Black 1 Dye
Authors: Pethkar Aniroodha V. , Bhagat Anirudh P.
Published: May 2013

India is one of the largest producer and exporter of dyestuff among developing countries. Large amount of dyes is lost in industrial effluents during production and industrial use. Persistence of dyes in the environment, their non-biodegradability and toxicity necessitate urgent steps to develop environment-friendly approaches to remove them from wastewaters. The present work describes attempts to use iron-based catalytic nanoparticles (NPs) for removal and degradation of Acid Black 1, one of the notoriously toxic dyes. A rapid screening assay was developed in order to select NPs possessing reducing properties. Methylene blue (MB) dye (0.1mg/L, 250µl) was exposed to different preparations of NPs (7mg) for 30 minute in a 96-well microtiter plate and read at 630 nm using an ELISA reader. Iron sulphide nanoparticles (FeSNPs) stabilized by a plant biopolymer (BP) could remove >95% MB and were selected for further studies. The FeSNPs could remove Acid Black 1 efficiently (73.8%) with specific dye removal capacity of 19.7 mg/g NPs. FeSNPs were immobilized in alginate beads (average diameter 3.45 mm) and packed in polypropylene columns (22.5 cm long, 3 cm i.d.) having bed volume of 42 ml. Acid black 1 solution (20 mg/L) was passed through the columns at predetermined flow rates in up-flow mode using peristaltic pump. The mass transfer kinetics were favourable at a flow rate of 2.2 ml/min (mass transfer coefficient 9.38X10-5 L.mg-1.min-1), and 120 bed volumes of the solution could be treated with efficiency exceeding 90%. Analysis of column effluent by UV-visible and FTIR spectroscopy revealed that removal of dye from solution was due to reductive degradation.
Solution Combustion Synthesis: Role of Oxidant to Fuel Ratio on Powder Properties
Authors: Jadhav L.D. , Patil S.P. , Jamale A.P. , Chavan A.U.
Published: May 2013

Solution combustion synthesis technique is one of the novel techniques used to prepare nanoparticles, multi-component ceramic oxides and nanocomposites with properties better than conventionally prepared one and these materials have been used for various applications such as sensors, catalysts, and materials for solid oxide fuel cell (SOFCs). In the present work, the method has been used to prepare nanoparticles of 10 mol% Gd doped ceria (GDC) and Cu and its oxides. The oxidant to fuel (O/F) ratio is found to affect the powder properties and even compositional homogeneity. In glycine-nitrate combustion synthesis of GDC, as revealed by XRD studies, phase pure nanoparticles with crystallite size in the range 9-12nm were obtained for all the O/F ratios. TEM measurements of calcined powder showed hexagonal shaped particles of roughly 20nm size. The exothermicity was increased with the oxidant to fuel ratio resulting in high surface area and soft agglomerates. A slightly lean O/F ratio gives surface area of 73 m2/g and soft agglomerates (D50= 5.34 mm), which eventually results into high sintering density at low temperature. Raman Spectra of GDC showed a sharp and intense peak at 467 cm−1which corresponds to CeO2due to F2gsymmetry of the cubic phase. In combustion synthesis of copper nitrate and citirc acid, the compositional homogenity and phase purity was affected by the oxidant to fuel ratio. The combustion at stoichiometric O/F ratio gives Cu nano particles, lean O/F ratio gives nanoparticles of Cu, CuO and Cu2O and rich ratio gives pure CuO nanoparticles. These nanoparticles have been studied with different characterization techniques like XRD, TG-DTA, SEM, TEM, FT-IR and Raman.
Incorporation of Modified Nano Montmorillonite (MMT) in Polyurethane Coatings Based on Acrylic Copolymer and Trimer of Isophorone Diisocyanate
Authors: Gite Vikas V. , Chaudhari Ashok B.
Published: May 2013

This work presents the synthesis of acrylic copolymer and trimer of isophorone diisocyanate (IPDI) for preparation of polyurethane (PU) coatings. Further we have studied the effect of silane modified nano montmorillonite (MMT) on the properties of PU coatings. Nano MMT was modified by vinyltriethoxysilane (TEVS) coupling agent and incorporated in PU coatings made from acrylic copolymers and trimer of IPDI. Acrylic copolymer was synthesized in the laboratory using butyl acrylate (BA), methyl methacrylate (MMA), styrene and hydroxyl ethyl acrylate (HEA) monomers. Coating properties of prepared PU coatings studied are gloss, impact resistance, flexibility, cross hatch adhesion and physicochemical properties include chemical resistance. The experimental results revealed that polyurethane coatings based on MMT based acrylic polyol and IPDI trimer showed good gloss and excellent adhesion. Thermal stability of these PU samples was found upto 229 °C. Physicochemical properties reflected that these PU have excellent chemical and solvent resistance.
Effect of Anisotropy on Magnetic Ordering in the Spinel System CoZnzGezCrx-zFe2-x-zO4
Authors: Jani Kalpesh H. , Joshi Amish G. , Joshi H.H.
Published: May 2013

The spinel ferrite system CoZnzGezCrx-zFe2-x-zO4with z= x2;x = 0.60, 0.65 and 0.70 was studied by Mà T (ZFC-FC) DC magnetization at low and high fields in the temperature range 5K to 300K, MàH measurements with high field up to 55 kOe at 15K temperature and low field AC susceptibility in temperature range 77K to 300K. We observe thermo-magnetic irreversibility (TMI) in MàT study, high field slope with high coercivity in MàH study. The composition x = 0.70 shows constricted hysterisis loop at 15K. We observed a cusp at transition temperature in AC susceptibility measurements. We have shown that the features observed in all these measurements are adequately explained using domain wall dynamics and inherent magneto-crystalline anisotropy without invoking the concept of cluster spin-glass type ordering in x = 0.60 and x = 0.65 in temperature range 5K to 300K. The sample x= 0.70, however showed signatures of cluster spin-glass type of ordering at low temperature as revealed in non-Brillouin type shape of low field FC curves in MàT DC magnetization and constricted hysterisis loop at 15K temperature.
Effect of Chromium Substitution on the Structural, Magnetic and Electrical Properties of Nano Crystalline Co0.6Zn0.4Cu0.2CrxFe1.8-xO4 Ferrite
Authors: Singhal Sonal , Bhukal Santosh
Published: May 2013

Nano-crystalline Co0.6Zn0.4Cu0.2CrxFe1.8-xO4 (x = 0.2, 0.4, 0.6 and 0.8), have been synthesized using a citrate sol-gel auto combustion method and annealed at different temperature 400 °C, 600 °C, 800 °C and 1000 °C. The effect of chromium substitution on the structural, magnetic and dielectric properties of cobalt-zinc-copper ferrite has been studied. The structural and magnetic characteristics have been studied by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and Vibrating Sample Magnetometer (VSM) techniques. The X-ray diffractogram of all the annealed samples confirm the formation of single phase with Fd-3m space group. The crystalline sizes have been found to increase (from ~15 nm – to 60 nm) with the annealing temperature. The DC electrical resistivity of all the ferrites has been measured using a two-probe method between temperature range of 30 °C to 100 °C. The DC electrical resistivity of all the samples decrease with increase in temperature indicates semiconducting nature. However, the DC resistivity increase as the Cr3+ concentration increases because the Cr3+ ions enter the octahedral sites and reduce the electron exchange between Fe2+ and Fe3+ causing a decrease in polaron hopping of Fe2+-Fe3+ions. The value of the Seebeck coefficient (S) for all the ferrites is found to be positive indicating that all the ferrite samples behave as p-type semiconductors. The effect of copper chromium cation distribution among the tetrahedral (A) and octahedral (B) sites of Co-Zn substituted ferrite on magnetization and coercivity field have been investigated using VSM (vibrating sample magnetometer) technique. The decrease in the saturation magnetization (Ms) with increasing chromium content may be attributed to the copper and chromium enters into the octahedral site of the Co-Zn ferrite.
Yttrium Iron Garnet: Properties and Applications Review
Authors: Mallmann E.J.J. , Sombra A.S.B. , Goes J.C. , Fechine P.B.A.
Published: May 2013

Due to a fast progress in the development of communication systems, the dielectric and magnetic ceramics (ferrites) have become attractive to be used in devices. Although the ferrites of the spinel type were the first material to be used in the microwave range, garnets have smaller dielectric losses and, therefore, are chosen for many applications. High demands for modern electric applications in magnetic materials results in new techniques and products being permanently studied and researched, with a consequent appearance of new solutions for a wide applications series. This work presents the study of the ferrimagnetic composite, constituted by Y3Fe5O12 (YIG) and Gd3Fe5O12 (GdIG) phases, through solid state synthetic route and submitted to high-energy mechanical milling. Additionally, experiments were made in order to evaluate the electric and magnetic behavior of the composites at radio frequency and microwave range and then later suggest an adequate technological application. The composites were efficient as ferrite resonator antennas (FRAs) and microstrip antennas (thick films deposited on metalized surface alumina substrate by screen-printing technique), in the microwave frequency range. The experiments with FRAs showed satisfactory results due to the control of the antennas radiation characteristics and their tuning by the use of an external magnetic field. The composite resonators studied in this work can be important to the development of a third generation (3G) wideband antennas to cell phones and other wireless products.
Preparation and Characterization of Nanocomposites for Technological Applications
Authors: Aphesteguy Juan C. , Jacobo Silvia E.
Published: May 2013

Materials with both electrical and magnetic properties are required for various applications ranging from electric and magnetic shields, molecular electronics, and sensors to microwave absorbers. Conducting polymers with the addition of magnetic oxides composites are suitable for such uses. Such is the case of the polyaniline (PANI), an organic polymer, mixed with magnetite. We have prepared through a new chemical method a PANI/ Fe3O4 composite with different amount of magnetic oxide from 0.3% m/m on the composite up to 42% m/m. The final product is a powder with good solubility in some organic solvents as chloroform. Structural morphological studies, transport properties (the electrical conductivity as a function of temperature) and magnetic characterization were performed on the oxides, on PANI and on the composites. We have explored the answer of these composites as absorbers in the microwave region to determine its potential technological application. An interesting magnetoresistance (MR) behavior was observed. The results are related to the particle size and to the influence of the percentage of oxide in the composite.
Geology, Circle Lake, Baffin Island, Nunavut
Authors: Sanborn-Barrie M , Young M
Published: May 2013

Cumberland Peninsula, eastern Baffin Island, is an under-explored, frontier region with significant diamond, base- and precious-metal potential. Archean (2.97-2.77 Ga) foliated to gneissic tonalitic plutonic rocks with enclaves of >2.77 Ga semipelite,
ca. 2.88 Ga gabbro and rare ca. 2.92 Ga metavolcanic rocks form a structural basement, exposed in the south and north. Metasedimentary cover rocks of the Paleoproterozoic Hoare Bay group, exposed from the central to the northeast part of the peninsula, are in tectonic contact with the basement
gneisses. The cover sequence includes widespread semipelite-psammite with minor quartzite, marble, silicate- and oxide-facies
iron-formation, chert and graphitic-pyritiferous shale, and two geochemically-distinct strands of ultramafic-mafic metavolcanic rocks of pyroclastic origin. Basement and cover rocks are cut by 1.9-1.88 Ga charnockite, biotite-garnet granodiorite and lesser quartz diorite of the Qikiqtarjuaq plutonic
suite. Major structures and medium to high-grade metamorphic assemblages are attributed to polyphase tectonometamorphism between ca. 1.90-1.84 Ga.
The pulse as diagnostic aid in Graeco-Roman times and the Mediaeval Ages
Authors: Retief Francois P. , Cilliers Louise
Published: May 2013

The aim of this article is to highlight a particular contribution in the history of medicine made by ancient physicians more than two millennia ago. In modern times the taking of the pulse as clinical tool is self-evident, but the fact that doctors in Graeco-Roman times and the Medievel Ages, when so little was known of physiology and especially of the cardiovascular system, could measure the pulse beat to diagnose, evaluate and treat diseases, is quite remarkable. As such it is a forerunner of the modern taking of the pulse, though physicians today have more sophisticated ways to detect illnesses.
The use of the Delphi survey as a research tool in understanding church trends
Authors: Elkington Robert L. , Lotter George
Published: May 2013

In the practical theological research process, as in most disciplines, extant literature is vital in assisting a researcher to formulate a foundational understanding of the topic under review. A literature review is also valuable in understanding the meta-theoretical aspects of the research topic. What does a researcher do, though, if there is little current literature on the topic under scrutiny? If there is a small corpus of literature around a subject, the Delphi method can serve as an extremely helpful research tool. This article discussed the use of the Delphi survey in a practical theological research endeavour and surveyed its history from inception to current usage. The article also reviewed the various types of Delphi survey and supported the use of the Lockean Delphi survey in this particular example of practical theological research. The article finished with an actual Delphi survey of Canadian Evangelical church pastors as an example of how the Delphi method can be used as a research tool in practical theology. The article concluded that the Delphi survey is an extremely useful research tool across the wide domain of social science research.
The Aquaporin Channel Repertoire of the TardigradeMilnesium tardigradum
Authors: Grohme Markus A. , Mali Brahim , Wełnicz Weronika , Michel Stephanie , Schill Ralph O. , Frohme Marcus
Published: May 2013

Limno-terrestrial tardigrades are small invertebrates that are subjected to periodic drought of their micro-environment. They have evolved to cope with these unfavorable conditions by anhydrobiosis, an ametabolic state of low cellular water. During drying and rehydration, tardigrades go through drastic changes in cellular water content. By our transcriptome sequencing effort of the limnoterrestrial tardigrade Milnesium tardigradum and by a combination of cloning and targeted sequence assembly, we identified transcripts encoding eleven putative aquaporins. Analysis of these sequences proposed 2 classical aquaporins, 8 aquaglyceroporins and a single potentially intracellular unorthodox aquaporin. Using quantitative real-time PCR we analyzed aquaporin transcript expression in the anhydrobiotic context. We have identified additional unorthodox aquaporins in various insect genomes and have identified a novel common conserved structural feature in these proteins. Analysis of the genomic organization of insect aquaporin genes revealed several conserved gene clusters.
New Biosynthesis and Biological Actions of Avian Neurosteroids
Authors: Tsutsui Kazuyoshi , Haraguchi Shogo , Inoue Kazuhiko , Miyabara Hitomi , Ubuka Takayoshi , Hatori Megumi , Hirota Tsuyoshi , Fukada Yoshitaka
Published: May 2013

De novo neurosteroidogenesis from cholesterol occurs in the brain of various avian species. However, the biosynthetic pathways leading to the formation of neurosteroids are still not completely elucidated. We have recently found that the avian brain produces 7α-hydroxypregnenolone, a novel bioactive neurosteroid that stimulates locomotor activity. Until recently, it was believed that neurosteroids are produced in neurons and glial cells in the central and peripheral nervous systems. However, our recent studies on birds have demonstrated that the pineal gland, an endocrine organ located close to the brain, is an important site of production of neurosteroids de novo from cholesterol. 7α-Hydroxypregnenolone is a major pineal neurosteroid that stimulates locomotor activity of juvenile birds, connecting light-induced gene expression with locomotion. The other major pineal neurosteroid allopregnanolone is involved in Purkinje cell survival during development. This paper highlights new aspects of neurosteroid synthesis and actions in birds.
Quality and precision processing of barley grain affected intake and digestibility of dry matter in feedlot steers
Authors: Yang W. Z. , Oba M. , McAllister T. A.
Published: May 2013

Yang, W. Z., Oba, M. and McAllister, T. A. 2013. Quality and precision processing of barley grain affected intake and digestibility of dry matter in feedlot steers. Can. J. Anim. Sci. 93: 251–260. A study was conducted to determine the impact of barley quality and precision processing to account for the impact of variable kernel uniformity on ruminal pH and fermentation, and digestibility in the digestive tract of steers. Eight ruminally cannulated steers were used in a replicated 4×4 Latin square experiment. The four diets consisted of light-weight barley (LB) precision-processed with roller setting based on kernel size; heavy-weight barley (HB) precision-processed; LB and HB grain mixed equal parts then processed at a single roller setting (CON); or LB and HB precision-processed and mixed equal parts (PP). The diets consisted of 10% barley silage and 90% concentrate [dry matter (DM) basis]. Dry matter intake by steers fed LB was greater (P=0.04) than by steers fed HB. Intakes of DM and other nutrients were greater (P=0.04) for steers fed PP than for steers fed CON. There were no differences (P>0.14) in ruminal pH and fermentation among treatments. Digestibility of DM in the total digestive tract tended (P=0.06) to be less with LB than with HB. Precision processing increased digestibility of crude proteion (P=0.04) and acid detergent fibre (P=0.06) resulting in a trend (P=0.10) towards increasing organic matter digestibility as compared with CON. The results suggest that screening of blended barley into more uniform fractions and precision processing of each fraction could increase intake of digestible nutrients for feedlot cattle.
Packing plant differences in meat quality for grain-fed veal
Authors: Campbell C. P. , Haley J. , Swanson K. C. , Mandell I. B.
Published: May 2013

Campbell, C. P., Haley, J., Swanson, K. C. and Mandell, I. B. 2013. Packing plant differences in meat quality for grain-fed veal. Can. J. Anim. Sci. 93: 205–215. Packing plant differences in meat quality were investigated in grain-fed veal from three commercial packing plants and a university research facility. Postmortem chilling rates were investigated in three plants including facilities which encased carcass sides in a polyliner bag intended to reduce shrinkage during chilling. Packing plant differences (P ≤ 0.01) in chilling rates were not always accompanied by plant differences in sarcomere length for longissimus or semitendinosus muscles. Drip and cooking losses and shear force for longissimus varied (P≤0.04) across packing plant with lower (P≤0.02) values found in veal slaughtered at the university research facility vs. veal from commercial packing plants. A packing plant by postmortem ageing interaction (P<0.05) for shear force was due to differences in extent of postmortem tenderization with ageing across packing plants. While use of a polyliner to encase the carcass during chilling decreased (P<0.001) rate of chilling and carcass shrinkage, there was no effect (P>0.20) on drip loss, shear force, or cooking losses vs. carcasses chilled uncovered.
Adhesive contact delaminating at mixed mode, its thermodynamics and analysis
Authors: Rossi Riccarda , Roubíček Tomáš
Published: May 2013

An adhesive unilateral contact problem between visco-elastic heat-conductive 1 bodies in linear Kelvin-Voigt rheology is scrutinized. The flow-rule for debonding the adhesive is considered rate-independent, unidirectional, and non-associative due to dependence on the mixity of modes of delamination, namely of Mode I (opening) and of Mode II (shearing). Such mode-mixity dependence of delamination is a very pronounced (and experimentally confirmed) phenomenon typically considered in engineering models. An anisothermal, thermodynamically consistent model is derived, considering a heat-conductive viscoelastic material and the coupling via thermal expansion and adhesion-depending heat transition through the contact surface. We prove the existence of weak solutions by passing to the limit in a carefully designed semi-implicit time-discretization scheme.
Well-posedness and qualitative behaviour of solutions for a two-phase Navier–Stokes-Mullins–Sekerka system
Authors: Abels Helmut , Wilke Mathias
Published: May 2013

We consider a two-phase problem for two incompressible, viscous and immiscible fluids which are separated by a sharp interface. The problem arises as a sharp interface limit of a diffuse interface model. We present results on local existence of strong solutions and on the long-time behavior of solutions which start close to an equilibrium. To be precise, we show that as time tends to infinity, the velocity field converges to zero and the interface converges to a sphere at an exponential rate.
Polygonal Hele–Shaw problem with surface tension
Authors: Kimura Masato , Tagami Daisuke , Yazaki Shigetoshi
Published: May 2013

We study a polygonal analogue of the Hele–Shaw moving boundary problem 1 with surface tension based on a framework of polygonal motion proposed by Benesˇ et al. [5]. A key idea is to introduce a polygonal Dirichlet-to-Neumann map. We study variational properties of the polygonal Dirichlet to-Neumann map and show that our polygonal Hele–Shaw problem is a polygonal analogue of the original problem. Local solvability of a polygonal Hele–Shaw problem is also proved by means of the variational structure.
Cobweb Theorems with Production Lags and Price Forecasting
Authors: Dufresne Daniel , Vázquez-Abad Felisa
Published: May 2013

The classical cobweb theorem is extended to include production lags and price forecasts. Price forecasting based on a longer period has a stabilizing effect on prices. Longer production lags do not necessarily lead to unstable prices; very long lags lead to cycles of constant amplitude. The classical cobweb requires elasticity of demand to be greater than that of supply; this is not necessarily the case in a more general setting. Random shocks are also considered.
On the scaling effect in global surface air temperature anomalies
Authors: Varotsos C. A. , Efstathiou M. N. , Cracknell A. P.
Published: May 2013

Abstract. The annual and the monthly mean values of the land-surface air temperature anomalies from 1880–2011, over both hemispheres, are used to investigate the existence of long-range correlations in their temporal evolution. The analytical tool employed is the detrended fluctuation analysis, which eliminates the noise of the non-stationarities that characterize the land-surface air temperature anomalies in both hemispheres. The reliability of the results obtained from this tool (e.g., power-law scaling) is investigated, especially for large scales, by using error bounds statistics, the autocorrelation function (e.g., rejection of its exponential decay) and the method of local slopes (e.g., their constancy in a sufficient range). The main finding is that deviations of one sign of the land-surface air temperature anomalies in both hemispheres are generally followed by deviations with the same sign at different time intervals. In other words, the land-surface air temperature anomalies exhibit persistent behaviour, i.e., deviations tend to keep the same sign. Taking into account our earlier study, according to which the land and sea surface temperature anomalies exhibit scaling behaviour in the Northern and Southern Hemisphere, we conclude that the difference between the scaling exponents mainly stems from the sea surface temperature, which exhibits a stronger memory in the Southern than in the Northern Hemisphere. Moreover, the variability of the scaling exponents of the annual mean values of the land-surface air temperature anomalies versus latitude shows an increasing trend from the low latitudes to polar regions, starting from the classical random walk (white noise) over the tropics. There is a gradual increase of the scaling exponent from low to high latitudes (which is stronger over the Southern Hemisphere).
The seaweeds Fucus vesiculosus and Ascophyllum nodosum are significant contributors to coastal iodine emissions
Authors: Huang R.-J. , Thorenz U. R. , Kundel M. , Venables D. S. , Ceburnis D. , Ho K. F. , Chen J. , Vogel A. L. , Küpper F. C. , Smyth P. P. A. , Nitschke U. , Stengel D. B. , Berresheim H. , O'Dowd C. D. , Hoffmann T.
Published: May 2013

Abstract. Based on the results of a pilot study in 2007, which found high mixing ratios of molecular iodine (I2) above the intertidal macroalgae (seaweed) beds at Mweenish Bay (Ireland), we extended the study to nine different locations in the vicinity of Mace Head Atmospheric Research Station on the west coast of Ireland during a field campaign in 2009. The mean values of I2 mixing ratio found above the macroalgae beds at nine different locations ranged from 104 to 393 ppt, implying a high source strength of I2. Such mixing ratios are sufficient to result in photochemically driven coastal new-particle formation events. Mixing ratios above the Ascophyllum nodosum and Fucus vesiculosus beds increased with exposure time: after 6 h exposure to ambient air the mixing ratios were one order of magnitude higher than those initially present. This contrasts with the emission characteristics of Laminaria digitata, where most I2 was emitted within the first half hour of exposure. Discrete in situ measurements (offline) of I2 emission from ambient air-exposed chamber experiments of L. digitata, A. nodosum and F. vesiculosus substantially supported the field observations. Further online and time-resolved measurements of the I2 emission from O3-exposed macroalgal experiments in a chamber confirmed the distinct I2 emission characteristics of A. nodosum and F. vesiculosus compared to those of L. digitata. The emission rates of A. nodosum and F. vesiculosus were comparable to or even higher than L. digitata after the initial exposure period of ~20–30 min. We suggest that A. nodosum and F. vesiculosus may provide an important source of photolabile iodine in the coastal boundary layer and that their impact on photochemistry and coastal new-particle formation should be reevaluated in light of their longer exposure at low tide and their widespread distribution.
Atmospheric column-averaged mole fractions of carbon dioxide at 53 aircraft measurement sites
Authors: Miyamoto Y. , Inoue M. , Morino I. , Uchino O. , Yokota T. , Machida T. , Sawa Y. , Matsueda H. , Sweeney C. , Tans P. P. , Andrews A. E. , Patra P. K.
Published: May 2013

Abstract. Atmospheric column-averaged mole fractions of carbon dioxide (XCO2) at 53 locations around the world were derived from aircraft measurements covering the altitude range of about 1–10 km. We used CO2 vertical profile measurements from three major carbon cycle programs, a global climatological data set of air number density profiles and tropopause height for calculating XCO2 for the period of 2007–2009. Vertical profiles of the CO2 mixing ratio are complemented by tall tower data up to 400 m from the earth's surface and by simulated profiles in the stratosphere from a chemistry-transport model. The amplitude of the seasonal cycle of calculated XCO2 values shows clear latitudinal dependence, and the amplitude decreases from about 10 ppm at high latitudes in the Northern Hemisphere to at most 2 ppm in the tropics and the Southern Hemisphere. The uncertainties of XCO2 were estimated from assumptions about CO2 profiles for each flight. Typically, uncertainties were less than 1 ppm; thus, this data set is within the level of uncertainty needed for primary validation of XCO2 measurements by the Greenhouse gases Observing SATellite (GOSAT) and by future satellite missions for monitoring greenhouse gases.
Why unprecedented ozone loss in the Arctic in 2011? Is it related to climate change?
Authors: Pommereau J.-P. , Goutail F. , Lefèvre F. , Pazmino A. , Adams C. , Dorokhov V. , Eriksen P. , Kivi R. , Stebel K. , Zhao X. , van Roozendael M.
Published: May 2013

Abstract. An unprecedented ozone loss occurred in the Arctic in spring 2011. The details of the event are revisited from the twice-daily total ozone and NO2 column measurements of the eight SAOZ/NDACC (Système d'Analyse par Observation Zénithale/Network for Detection of Atmospheric Composition Changes) stations in the Arctic. It is shown that the total ozone depletion in the polar vortex reached 38% (approx. 170 DU) by the end of March, which is larger than the 30% of the previous record in 1996. Aside from the long extension of the cold stratospheric NAT PSC period, the amplitude of the event is shown to be resulting from a record daily total ozone loss rate of 0.7% d−1 after mid-February, never seen before in the Arctic but similar to that observed in the Antarctic over the last 20 yr. This high loss rate is attributed to the absence of NOx in the vortex until the final warming, in contrast to all previous winters where, as shown by the early increase of NO2 diurnal increase, partial renoxification occurs by import of NOx or HNO3 from the outside after minor warming episodes, leading to partial chlorine deactivation. The cause of the absence of renoxification and thus of high loss rate, is attributed to a vortex strength similar to that of the Antarctic but never seen before in the Arctic. The total ozone reduction on 20 March was identical to that of the 2002 Antarctic winter, which ended around 20 September, and a 15-day extension of the cold period would have been enough to reach the mean yearly amplitude of the Antarctic ozone hole. However there is no sign of trend since 1994, either in PSC (polar stratospheric cloud) volume (volume of air cold enough to allow formation of PSCs), early winter denitrification, late vortex renoxification, and vortex strength or in total ozone loss. The unprecedented large Arctic ozone loss in 2011 appears to result from an extreme meteorological event and there is no indication of possible strengthening related to climate change.
On the interference of Kr during carbon isotope analysis of methane using continuous-flow combustion–isotope ratio mass spectrometry
Authors: Schmitt J. , Seth B. , Bock M. , van der Veen C. , Möller L. , Sapart C. J. , Prokopiou M. , Sowers T. , Röckmann T. , Fischer H.
Published: May 2013

Abstract. Stable carbon isotope analysis of methane (δ13C of CH4) on atmospheric samples is one key method to constrain the current and past atmospheric CH4 budget. A frequently applied measurement technique is gas chromatography (GC) isotope ratio mass spectrometry (IRMS) coupled to a combustion-preconcentration unit. This report shows that the atmospheric trace gas krypton (Kr) can severely interfere during the mass spectrometric measurement, leading to significant biases in δ13C of CH4, if krypton is not sufficiently separated during the analysis. According to our experiments, the krypton interference is likely composed of two individual effects, with the lateral tailing of the doubly charged 86Kr peak affecting the neighbouring m/z 44 and partially the m/z 45 Faraday cups. Additionally, a broad signal affecting m/z 45 and especially m/z 46 is assumed to result from scattered ions of singly charged krypton. The introduced bias in the measured isotope ratios is dependent on the chromatographic separation, the krypton-to-CH4 mixing ratio in the sample, the focusing of the mass spectrometer as well as the detector configuration and can amount to up to several per mil in δ13C. Apart from technical solutions to avoid this interference, we present correction routines to a posteriori remove the bias.
Error budget analysis of SCIAMACHY limb ozone profile retrievals using the SCIATRAN model
Authors: Rahpoe N. , von Savigny C. , Weber M. , Rozanov A.V. , Bovensmann H. , Burrows J. P.
Published: May 2013

Abstract. A comprehensive error characterisation of SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY) limb ozone profiles has been established based upon SCIATRAN transfer model simulations. The study was carried out in order to evaluate the possible impact of parameter uncertainties, e.g., in albedo, stratospheric aerosol optical extinction, temperature, pressure, pointing and ozone absorption cross section on the limb ozone retrieval. Together with the a posteriori covariance matrix available from the retrieval, total random and systematic errors are defined for SCIAMACHY ozone profiles. Main error sources are the pointing errors, errors in the knowledge of stratospheric aerosol parameters, and cloud interference. Systematic errors are on the order of 7%, while the random error amounts to 10–15% for a single profile for most part of the stratosphere. These numbers can be used for the interpretation of instrument intercomparison and validation of the SCIAMACHY limb ozone profiles in a rigorous manner.
A new microwave spectrometer for ground-based observations of water vapour
Authors: Hallgren K. , Hartogh P. , Jarchow C.
Published: May 2013

Abstract. We have developed a new, high time-resolution, microwave heterodyne spectrometer for observations of water vapour in the middle atmosphere. It measures the rotational transition of water vapour at 22.235 GHz in the vertical and horizontal polarisation. The two polarisations are averaged in order to optimise the signal-to-noise ratio. The different polarisations have separate, but identical, signal chains consisting of a 22 GHz cooled HEMT amplifier, a second, warm, 22 GHz HEMT booster amplifier, an IF stage and a Chirp Transform Spectrometer (CTS) backend. Continuous calibration with two internal loads kept at temperatures close to the observed atmosphere, a wobbling optical table to reduce standing waves in the optical path and the low receiver temperature ensures a time resolution of an order of magnitude better than what has been achieved by earlier instruments. The error sources in the retrieved spectrum are discussed and the data is compared and validated against EOS-MLS on the NASA Aura satellite. The profiles are found to be in good agreement with each other.
A short history of ocean acidification science in the 20th century: a chemist's view
Authors: Brewer P. G.
Published: May 2013

Abstract. This review covers the development of ocean acidification science, with an emphasis on the creation of ocean chemical knowledge, through the course of the 20th century. This begins with the creation of the pH scale by Sørensen in 1909 and ends with the widespread knowledge of the impact of the "High CO2 Ocean" by then well underway as the trajectory along the IPCC scenario pathways continues. By mid-century the massive role of the ocean in absorbing fossil fuel CO2 was known to specialists, but not appreciated by the greater scientific community. By the end of the century the trade-offs between the beneficial role of the ocean in absorbing some 90% of all heat created, and the accumulation of some 50% of all fossil fuel CO2 emitted, and the impacts on marine life were becoming clear. This paper documents the evolution of knowledge throughout this period.