bluuebunny/crossref_metadata_2025 huggingface dataset:
Depth Profile of Chemical Composition and Free Volume of Polyurethane-Urea/Clay Nanocomposite
Authors: Rath Sangram K. , Patri Manoranjan , Maheshwari Priya , Sudarshan Kathi , Pujari Pradeep K. , Khakhar Devang V.
Published: November 2012

Depth profile of subsurface chemical composition and free volume in segmented polyurethane-urea/clay nanocomposites was studied by angle resolved X-ray photoelectron spectroscopy (ARXPS) and Doppler broadening energy spectroscopy (DBES) using slow positron beam. The ARXPS studies revealed increasing N/C atomic ratio (hard segment to soft segment ratio) at any given depth for the clay loaded samples compared to the neat polymer. DBES study revealed significant microstructure modification with clay loading. Self segregation of hard and soft segments in neat polymer and their interspersing with clay loading was observed from DBES measurements.
o-Ps Lifetimes in Iron Containing Micro- and Mesoporous Media
Authors: Dung Tran Quoc , Lázár K. , Havancsák K. , Kajcsos Z.
Published: November 2012

Positron annihilation lifetime (LT) measurements were used to study the influence of addition of iron on ortho-positronium (o-Ps) in micro and mesoporous media. Three types of porous samples containing iron were chosen for the investigation. LT spectra were decomposed to four components in the 0.1 - 50 ns lifetime range. An attempt is made to correlate the data with sites occupied by iron in the framework as derived from Mössbauer studies. No significant correlation could be detected in this respect. Instead, dominating role of presence or absence of iron can be deduced. Certain influence can also be attributed to the presence of adsorbed water.
Positron and Positronium Annihilation as Probes to Identify Cation Substitution Effects in CoCrxFe2-xO4
Authors: Nambissan P.M.G. , Lakhani Vinay K. , Modi Kunal B.
Published: November 2012

CoCrxFe2-xO4 samples with x = 0.0 to 2.0 were prepared by air oxidation of aqueous suspension containing Co2+, Cr3+ and Fe3+ ions and characterized by x-ray diffraction. Positron lifetime and coincidence Doppler broadening (CDB) measurements indicated three distinct stages of positron trapping in defects. Initially the vacancy-type defects located at the A-sites (tetrahedral) trapped positrons but, with the substitution of Fe by Cr in low concentrations (x <= 0.7), positrons are trapped by defects at the B-sites (octahedral). Mossbauer spectroscopic results indicated the cationic distribution at B-sites to be stoichiometry-dependent and, till x = 0.7, the deficiency of Fe3+(B) ions was compensated by interchange of Fe3+(A) ions with Co2+(B) ions. Between x = 0.9 and 1.7, the substitution resulted in continued decrease of Fe3+(B) ions and the structure got fully transformed into a normal spinel configuration during x = 1.8 to 2.0.
Ni-Substitution Induced Inversion in ZnFe2O4 Seen by Positron Annihilation
Authors: Nambissan P.M.G. , MONDAL OINDRILA , Chakrabarty C. , Pal M.
Published: November 2012

We report in this work about the inversion of the spinel structure of ZnFe2O4 induced by the substitution of Zn2+ by Ni2+ ions. Positron lifetimes were measured in Zn1-xNixFe2O4 with different concentrations (x) of doped Ni2+ ions and a drastic change across x = 0.4 – 0.6 was observed, which is attributed to this transformation. The interchange of positions of the cations on doping leaves a fraction of them unoccupied and these vacancies act as positron trapping centres. Since Ni2+ is smaller in size than Zn2+, defects due to non-stoichiometry are less in NiFe2O4 than in ZnFe2O4. The increase in positron lifetime implies the trapping of positrons being shifted from A- to B-sites and is an indication of the transformation from inverse to normal spinel configuration. Coincidence Doppler broadening measurements supported these findings.
Effect of Sintering on Defects in Yttria Stabilised Zirconia
Authors: Procházka Ivan , Čížek Jakub , Melikhova Oksana , Anwand Wolfgang , Brauer Gerhard , Konstantinova Tatjana E. , Danilenko Igor A.
Published: November 2012

A variable energy slow positron beam was utilised to investigate depth dependent effects of sintering on the tetragonal yttria stabilised zirconia nanopowders. Positron implantation was combined with the determination of Doppler broadened profiles of annihilation radiation. The results are consistent with recent positron lifetime data showing that sintering at elevated temperatures leads to a disappearance of pores and a significant grain growth, which is demonstrated by a strong suppression of positronium formation and a substantial decrease in concentration of open volume defects at triple points, respectively, with increasing sintering temperature. An existence of a subsurface layer of a relatively high content of defects was shown in sintered samples and tentatively attributed to arise from a diffusion of open volume defects from the sample interior toward the surface or from a sintering-induced surface modification.
Thermal Annealing Influence on Ions Implanted Fe-Cr Model Alloys
Authors: Sojak Stanislav , Slugeň Vladimir , Kršjak V. , Egger W. , Ravelli L. , Petriska M. , Stanček S. , Skarba M. , Priputen Pavol , Vitázek K. , Stacho M. , Veterníková J. , Sabelová V.
Published: November 2012

Abstract. Binary Fe-11.62wt%Cr alloys were investigated in as-received state as well as after a two step helium ion implantation at different energies (100 keV and 250 keV) with doses up to 3.12×1018 cm-2. In order to study changes in alloys in dependence on the temperature, thermal annealing was performed at temperatures of 400, 475, 525 and 600 °C and specimens were afterwards measured by a pulsed low energy positron system (PLEPS). Annealing out of defects at lower temperatures was not as significant as expected, and we also encountered difficulties with defect identification. However, an apparent decrease of defect size was observed in the specimen annealed at a temperature of 600 °C.
Ps Bubble in Liquids
Authors: Zgardzińska Bożena
Published: November 2012

Ortho-positronium lifetime in alkanes and alcohols was measured in a broad range of temperatures. The results were compared with predictions of the bubble model. The bubble radius can be determined from the Tao-Eldrup equation as well as calculated using the model. The depth of potential well and surface tension are the main factors ruling the Ps bubble size. The best fit of the bubble model to the experimental data is obtained assuming the rectangular potential well to be 1 eV deep (equivalent to an infinite one broadened by 0.166 nm) and the microscopic surface tension increased about 3 times comparing to the macroscopic one.
The LEPTA Facility for Fundamental Studies of Positronium Physics and Positron Spectroscopy
Authors: Sidorin Aleksey A. , Meshkov Igor , Ahmanova E. , Eseev M. , Kobets A. , Lokhmatov V. , Pavlov V. , Rudakov A. , Yakovenko S.
Published: November 2012

At present time the Low Energy Positron Toroidal Accumulator (LEPTA) at JINR is under commissioning with circulating positron beam. The LEPTA facility is a small positron storage ring equipped with the electron cooling system and positron injector. The maximum positron energy is of 10 keV. The storage ring is aimed for generation of direct fluxes of ortho-positronium (o-Ps), produced in recombination of the positron beam circulating in the ring with single pass cooling electron beam. The project has few goals: annihilation spectroscopy (PAS) to monitoring defects of nanometer sizes in materials as a function of depth managed by the positron energy in a rage of a few eV to 100 keV.
Software for Digital Coincidence Doppler Broadening Setup
Authors: Petriska Martin , Sabelová Veronika , Slugeň Vladimir , Sojak Stanislav , Stacho Matúš , Veterníková Jana
Published: November 2012

An advanced digital measurement system for Coincidence Doppler broadening (CDB) technique is presented. Traditional CDB setups are based on shaping amplifiers and multi parameter multi-channel analyzers (MCA). We replaced them by 14-bit data acquisition card (DAQ). Replacing multi-parameter MCA by DAQ was realized also by several groups before, but in our setup the signal shaping tasks are performed digitally by software in a personal computer. Signals from high purity (HP) Ge detectors are sampled at preamplifier outputs. Pulse shaping is realized by a trapezoidal filter.
An AMOC System with Two Detectors
Authors: Li Zhuo Xin , Yu Run Sheng , Cao Xing Zhong , Zhang Peng , Qin Xiu Bo , Wang Bao Yi
Published: November 2012

In this work, a single scintillator detector setup for AMOC measurement is considered to improve coincidence efficiency. A planar HPGe detector provide both the timing signal of stop channel and the energy spectrum signal for an annihilation events of positronium. Experiment results show that the system can get a count rate ~20cps/μCi with a time resolution of 2.2ns.
The Free Volume Dynamics
Authors: Račko Dušan , Krištiak Jozef
Published: November 2012

In the present contribution the dynamics of the intermolecular free volume is investigated. For this purpose a new computational algorithm has been proposed and programmed. The free volume is analyzed along the atomistic trajectory obtained by molecular dynamics simulations and a picture on time averaged free volume structure is obtained. The picture showed two distinct regimes of the free volume dynamics at pico-second and nano-second time-scale in liquid. The analysis has shown that at the time scale of the ortho-positronium lifetime and in the liquid phase the free volume microstructure ceases to exist in rigid cavities. This picture is consistent with the common considerations on the o-Ps existence, which suppose the o-Ps atom digging its own holes/cavities in liquids around the temperature of the o-Ps lifetime saturates.
A New Scintillator Geometry for Positronium Time of Flight Measurement
Authors: Jiang Xiao Pan , Cao Xing Zhong , Yu Run Sheng , Li Zhuo Xin , Zhang Peng , Qin Xiu Bo , Wang Bao Yi
Published: November 2012

The positronium time of flight (Ps-TOF) spectroscopy is a novel technique for studying the microstructure in porous materials, in which the high-efficient detection of γ rays generated from ortho-positronium annihilation is the key point for the apparatus setup. In this paper, a new geometry of the scintillator was proposed to improve the γ ray detection efficiency which was indicated by the 22.1% promotion using the simulation results.
Effect of Water on the Size Distribution of Free-Volume Holes in Nafion Membrane
Authors: Čížek Jakub , Barnovská Zuzana , Šourek Michal , Procházka Ivan
Published: November 2012

Positron lifetime spectroscopy was employed for investigation of the size distribution of free volume holes in Nafion N-1110 membrane. Size distribution of free volume holes was determined in the as-received and dried membrane and in the membrane immersed in water at various temperatures. It was found that absorbed water causes reduction of the mean size of free volume holes and increase of their dispersion and concentration. This indicates that free volumes are split by swollen ionic clusters absorbing water. The kinetics of water uptake and the amount of absorbed solvent was determined by in-situ measurement of the weight increase.
Annihilation Process of Positron in Degraded Nafion®-117
Authors: Honda Yoshihide , Aoyagi Yoshikazu , Tojo Sachiko , Akiyama Yoko , Nishijima Shigehiro
Published: November 2012

Annihilation process of positron in Nafion-117 was investigated under several kinds of conditions to elucidate degradation process of polymer electrolyte membrane. It was found that ortho-positronium stayed beside cluster wall and side chains and its lifetime reflected cluster size. Annihilation process of positron was found to be greatly influenced by the electronic state of sulfonic group. These results showed that positron annihilation spectroscopy would be good tool to detect degradation of polymer electrolyte membrane.
Positronium Lifetimes and Gas Permeation in Aquivion® for Fuel Cells
Authors: Mohamed Hamdy F.M. , Kobayashi Yoshinori , Kuroda Seiichi , Ohira Akihiro
Published: November 2012

Variations of ortho-positronium (o-Ps) lifetime and gas permeability of the Aquivion® E8705 membrane were studied as functions of temperature under vacuum and relative humidity at room temperature. When the temperature was varied between 0 and 100 °C in vacuum, the hole volume of Aquivion® E8705, deduced from the ortho-positronium lifetime, gradually increased. However, when the relative humidity was changed at room temperature, the hole volume was essentially unchanged. Good linear correlations between the logarithm of permeabilities of O2 and H2 and reciprocal hole volume at different temperatures indicates the importance role of free volume in gas permeation in dry Aquivion® E8705. However, for hydrated Aquivion® E8705 the permeability less depends on hole volume.
The Influence of Admixtures in n-Alkanes on Electron Traps
Authors: Pietrow Marek , Wawryszczuk Jan
Published: November 2012

The distribution of electron trap depths in hydrocarbons seems to be continuous in the range from 0.6 eV to 2.2 eV. However, it seems that among the deepest traps in n-heptane also the discrete ones appear as well. The influence of the admixture of other alkane on Ps intensity in alkanes was examined. As far as the admixture of an alkane with a shorter chain is concerned, the depth of the traps and their amount remain almost the same like in the case of the pure solvent. When it comes to essentially non-miscible solid heptane and nonane, a total lack of electron accumulation effects was observed. It is an exception among the mixed alkanes investigated here and needs a careful study.
Molecular Packing of Carbohydrate Oligomer Encapsulants - A Free Volume Perspective
Authors: Roussenova Mina , Townrow Sam , Murith Mathieu , Ubbink Job , Alam M. Ashraf
Published: November 2012

Positron annihilation lifetime spectroscopy (PALS) is used in conjunction with dilatometry to analyse the effects of water and low molecular weight diluents (maltose and glycerol) on the molecular organisation and density of carbohydrate oligomers commonly used in the pharmaceutical and food industries for the formulation of encapsulation matrices. In the glassy state, both maltose and glycerol act as packing enhancers, causing a non-linear decrease in the average molecular hole size of the carbohydrate matrices. Water exists in a highly non-ideal state in these systems and it alters the molecular organisation of the matrices in a complex manner, whereby it can act either as an anti-plasticiser or a plasticiser, depending on the level of hydration.
Study of the Effect of Cation Non-Stoichiometry of (La0.85Sr0.15)yMnO3 Manganite Single Crystals on the Magnetic Properties
Authors: Shulyatev Dmitry , Lyange Mariya , Pestun Anna , Mukovskii Yakov M. , Choi Eun Sang , Suslov Alexey
Published: November 2012

The influence of cation inhomogeneity on magnetic and electron transport properties of (La0.85Sr0.15)yMnO3 (y=0.92-0.97) single crystals were studied. It was found that both the temperature of ferromagnetic ordering TC and the temperature of orbital ordering TOO are increased with the Mn content decreasing. For all six samples studied two peaks on magnetoresistance curves were observed: the first near TC and the second close to TOO. The magnetic field does not affect the position of the former maximum, while it moves the latter towards lower temperatures.
Oxo-Bridged Trinuclear Fe(III) Complexes: Structural and Magnetic Properties
Authors: Silva Manuela Ramos , Nogueira João N.J. , Silva Pedro A.O.C. , Yuste-Vivas Consuelo , Pereira Laura C.J. , Waerenborgh João Carlos
Published: November 2012

The crystal structure of (µ3-Oxo)-hexakis(µ2-cyanoacetato)-triaqua-tri-iron(III) nitrate pentahydrate shows that the trinuclear ferric complex has an equilateral molecular structure which is manifested in the 57Fe Mössbauer spectrum single doublet. The magnetic measurements reveal antiferromagnetic exchange interactions of –22.85 cm-1, between the metal centers, that compel the system to a total spin ground state of S = ½.
Piperazinediium Diselenatohexaaquacobaltate(II) Dihydrate (C4H12N2)[Co(SeO4)2(H2O)4]·2H2O
Authors: Nkhili Nouha Loulou , Rekik Walid , Naili Houcine , Mhiri Tahar , Bataille Thierry
Published: November 2012

The new hybrid material, (C4H12N2)[Co(H2O)4(SeO4)2]·2H2O, has been synthesized by the slow evaporation method at room temperature and crystallographically characterized. It crystallizes in the monoclinic system, space group P21 /n. The crystal structure of this compound consists of transition metal, Co(II), octahedrally coordinated by four water molecules and two selenate groups forming the [Co(H2O)4(SeO4)2]2- anions, water molecules and piperazinediium cations (C4H12N2)2+ linked together by two types of hydrogen bonds, OW–H…O and N–H…O.
Thermodynamic Stability and Interfacial Reactions of CdS, ZnS and Cd1-xZnxS in Aqueous Solution
Authors: Maliy Liubov , Mokrousov Gennady
Published: November 2012

This study is devoted to understanding the thermodynamic basis of the process of synthesis of ZnS, CdS and their solid solutions in aqueous solutions in order to obtain thin films of required composition. The typical interfacial reactions were considered, and the thermodynamic calculations of the possible redox reactions and the reaction standard electrode potentials have been done. The composition of a solution is analyzed by means of thermodynamic diagrams as a function of redox potential versus pH. It has been demonstrated that the near-surface layer with the defect structure and the excess of sulfur on a surface can be formed in case of ZnS at pH < 1.5 during the synthesis. The application of obtained data in the synthesis of semiconducting materials is also shown.
Development of Mechanically Alloyed and Sintered W-1 wt.% Ni Matrix Composites Reinforced with TiB2
Authors: Agaogullari Duygu , Balci Özge , Demirkan Ö. Utku , Gokce Hasan , Genç Aziz , Öveçoğlu M. Lütfi , Duman Ismail
Published: November 2012

Due to improve the physical and mechanical properties of Ni activated W compacts, TiB2 was added to the W-Ni matrix as reinforcing agent. W-Ni matrix composites were fabricated by using a combined method of mechanical alloying (MA), cold pressing and activated sintering. The amount of activated sintering aid (Ni) was kept constant as 1 wt.%. The effects of TiB2 content and mechanical alloying duration on the physical, microstructural and mechanical properties of activated sintered W-Ni compacts were investigated. The results showed that TiB2 particles have a significant effect on the density and microhardness values of the sintered samples. After MA and sintering, formation of W2B and NiTi intermetallic compounds were observed because of the decomposition of TiB2. The relative density value of 91.21 % and microhardness value of 4.08±0.28 GPa of W-1 wt.% Ni samples respectively increased to 94.88 % and 5.64±0.28 GPa with the addition of 2 wt.% TiB2.
Microwave-Hydrothermal Synthesis of Transition Metal Tungstates with Nanosized Particles
Authors: Siqueira Kisla P.F. , Dias Anderson
Published: November 2012

Microwave-hydrothermal processing was employed to synthesize Mn and Co tungstates under environmentally friendly conditions. X-ray diffraction showed that crystalline, single-phase materials were produced. Incipient crystallized compounds were also obtained in some conditions, as verified by TEM. For these samples, nanostructured regions could be observed inside the amorphous matrix. Sintered solid-solutions of Mn1-xCoxWO4 compounds were produced to investigate the morphological and structural changes in the resulted ceramic. Raman spectroscopy was used to obtain a reliable set of spectra containing all the Raman-active bands predicted by group-theory calculations.
Reactive Milling of Magnesium under Hydrogen Using Transition Metals and their Fluorides as Additives
Authors: Leiva Daniel Rodrigo , Ishikawa Tomaz Toshimi , Miraglia Salvatore , Fruchart Daniel , Botta Filho Walter José
Published: November 2012

Magnesium is light, abundant and it can store up to 7.6 wt. % of hydrogen forming MgH2 and accordingly it is a promising material for hydrogen storage. Processing of Mg-based mixtures by high-energy ball milling (HEBM) can produce materials with high level H-sorption properties. In the present report, we display and compare the effects of different nanocrystalline additives (MgF2, Fe, NbH0,89, FeF3, VF3) on the formation of MgH2 by reactive milling. The H-desorption behavior of the as-prepared nanocomposites is also evaluated. A combined catalytic effect is observed due to the synergic action of MgF2 and Fe (or NbH0,89) on the hydrogenation rate during processing. The transition metal fluorides promote as well the MgH2 synthesis. By using more energy-intensive milling conditions and adequate additives in given proportions (e.g. 5 mol. % FeF3), is shown to be very effective for a full and fast synthesis (4 h) of MgH2 by reactive milling.
Relationship between Micro-/Nano-Structure and Stress Development in TM-Doped Mg-Based Alloys Absorbing Hydrogen
Authors: Skryabina N.E. , Pinyugzhanin Vladimir M. , Fruchart Daniel
Published: November 2012

In the most recent years, MgH2 has attracted considerable attention for reversible hydrogen storage purposes because of a large 7.6 w% H-uptake, single plateau reaction at low pressure and abundance of metal. If the Mg ↔ H reactions take place at rather high temperature (> 300°C), the kinetic remains very low. However, early transition metal based additives (Ti, V, Nb...) improve dramatically the kinetics of hydrogen absorption/desorption, while having no essential impact on the reversible sorption capacity. Systematic analysis of many experimental data led to question chemical, physical, mechanical... parameters contributing significantly to improve the kinetics of absorption/desorption. Besides, results of theoretical and numerical computation enlighten the impact of structural and mechanical parameters owing to the local bonds of Mg/MgH2 with of TM elements, in terms of total energy and electronic structure. More specifically, we found highly relevant to consider 1 - the impact of the crystallite sizes of Mg and the TM-phase, 2 - the role of internal and external stresses, as well as 3 - the role of texture on the kinetics of hydrogen absorption/desorption. Apart the previous considerations, we like to underline the role of specific TM in trapping intermediately hydrogen thus forming TMHx prior initiating the Mg ↔ MgH2 nucleation process.
Sintering and Electrochemical Properties of Hydrogen Storage Alloys in the System Mg-Ni
Authors: Esaka Takao , Nanbu Eisuke
Published: November 2012

We synthesized ceramic-type Mg2Ni alloys (hydrogen storage alloy) by sintering at high temperature in Ar atmosphere and applied the sintered materials to the anode of the metal hydride batteries. As a result, it was found that the samples were obtained as sintered alloys, mainly composed of hexagonal phase with a little MgO. The discharge capacity of the sintered sample was more than 150 mAhg-1 on the 1st cycle. It decreased to lower than 50 mAhg-1 after a few cycles, but the capacity was maintained over 20 cycles. The cycling capacity retention is due to the packed fusion of the alloy particles by sintering, which denotes a good effect of sintering method to prepare alloy materials.
Theoretical Search for p-Type Dopants in Mg2X (X= Si, Ge) Semiconductors for Thermoelectricity
Authors: Toboła Janusz , Zwolenski Piotr , Kaprzyk Stanisław
Published: November 2012

Electronic structure calculations of doped Mg2(Si-Ge) semiconductors were performed by the charge self-consistent Korringa-Kohn-Rostoker method with the coherent potential approximation (KKR-CPA) in order to search for p-type impurities. It was predicted that Li and Na (located on Mg site) as well as B, Ru, Mo and W (located on Si site) are expected to behave as hole donors in Mg2(Si-Ge). Using the calculated density of states in doped Mg2Si in the vicinity of the Fermi level, the linear term of thermopower was also estimated from the simplified Mott's formula. The RT Seebeck coefficient may range from 120μV/K (Li) to almost 300μV/K (Ru) at the 1% content of doped impurities.
Structural, Magnetic and Transport Properties of the Rare-Earth Cage Compound Ce4Pd12Sn25
Authors: Lorenzer K.A. , Dalladay Simpson P. , Kubel F. , Sidorenko A. , Prokofiev A. , Paschen S.
Published: November 2012

Here we present and discuss structural, magnetic and transport properties of the new ternary cage compound Ce4Pd12Sn25. The isostructural Pt analogue, Ce4Pt12Sn25 has previously been characterized as a metallic Kondo lattice system with a very low Kondo temperature TK ~ 0.25 K and an antiferromagnetic ground state with a Neel temperature TN =0.19 K. In contrast to the expectations that the smaller unit cell volume of Ce4Pd12Sn25 compared to Ce4Pt12Sn25 will weaken the magnetism and tune the system closer to a magnetic instability, we found evidence for a phase transition at a higher temperature Tmag=0.265 K.
The BaAl4 Structure and its Derivatives from the R-Zn-Ga Systems
Authors: Verbovytskyy Yuriy , Gonçalves Antonio Pereira
Published: November 2012

Seven new ternary RZn1+xGa3-x (R = Ce, Pr, Nd, Sm, Ho and Er) and R5Zn2Ga17 (R = Ce) phases are synthesized for the first time. Their crystal structures are solved on basis of X-ray powder diffraction data. The above mentioned compounds belong to the BaAl4 (space group I4/mmm) and Rb5Hg19 (space group I4/m) structure types. Details of the structure of the Ce5Zn2Ga17 compound and relationship with RZn2-xGa2+x (BaAl4 type) and R3Zn8-xGa3+x (La3Al11 type) are briefly discussed.
Influence of Ru on the Magnetic Properties of Y2T17 (T = Co, Fe)
Authors: Andreev Alexander V. , Gorbunov Denis I. , Tereshina Evgeniya A. , Šebek Josef , Šantavá Eva , Daniš Stanislav , Pospíšil Jiří
Published: November 2012

Influence of Ru substitution on magnetic properties of Y2Fe17 and Y2Co17 (hexagonal structure of the Th2Ni17-type) has been studied on single-crystalline samples. Whereas in the Y2Fe17-xRux system ferromagnetism is transformed rapidly into antiferromagnetism with a field-induced metamagnetic transition, in Y2Co17-xRux only a monotonous decrease of spontaneous magnetic moment, Curie temperature and first anisotropy constant is observed.
Magnetic Properties of a HoFe5Al7 Single Crystal
Authors: Gorbunov Denis I. , Andreev Alexandr V.
Published: November 2012

A single crystal of HoFe5Al7 (tetragonal ThMn12 structure) has been studied. HoFe5Al7 orders ferrimagnetically at TC = 227 K and has a compensation of the Ho and Fe sublattices at Tcomp = 65 K. The compound exhibits high easy-plane anisotropy. Strong anisotropy is also present within the basal plane, with the [110] axis being the easy magnetization direction. A high coercivity with Hc values attaining 1.6 T is found at 2 K. In the temperature range 40-80 K, HoFe5Al7 displays a field-induced magnetic transition along the easy [110] direction. Temperature dependence of the critical field Hcr of the transition is very strong, Hcr exceeds 14 T below 40 K.
d-Band Magnetism of Ag, Au, Pd and Pt Studied with XMCD
Authors: Bartolomé Juan , Figueroa Adriana Isabel , Bartolomé Fernando , García Luis Miguel , Wilhelm Fabrice , Rogalev Andrei
Published: November 2012

Metals which are non-magnetic in bulk form may present magnetism when shaped in reduced dimensions. Ag, Au, Pd and Pt nanoparticles have shown this behavior. They have in common an incompletely filled 4d (Au, Pd) or 5d-band (Au, Pt), that gives rise partially to this type of magnetism. By means of Xray Magnetic Circular Dichroism (XMCD) at the L2,3 edges the orbital and spin contributions to the magnetic moment stemming from the d-band has been explored. The different magnetic response of these metals, as viewed with XMCD, is revised.
Bone Turnover Markers in Patients with Type 1 Gaucher Disease
Authors: Giuffrida Gaetano , Cingari Maria Rocca , Parrinello Nunziatina , Romano Alessandra , Triolo Anna , Franceschino Magda , Di Raimondo Francesco
Published: November 2012

Bone complications occur frequently in Gaucher disease (GD) and reduce the quality of life of these patients. Skeletal involvement is an important indication for treatment to ameliorate symptoms and reduce the risk of irreversible and debilitating disease. Bone biomarkers have been used to assess disease status and the response to therapy in a number of bone disorders. Here, we examine the literature for evidence of abnormalities in bone turnover markers in patients with type 1 GD to assess whether they might be useful for the assessment of bone involvement in GD. We have found that bone biomarkers in GD show highly variable results which do not currently support their routine use for clinical assessment of bone status, as an indication for therapy initiation, or for monitoring the response to therapy. A greater understanding of bone markers and their relation to the bone manifestations of GD is required.
Anaesthetic management of a 10-month-old white rhinoceros (Ceratotherium simum) calf for emergency exploratory celiotomy
Authors: Zeiler Gareth E. , Stegmann George F.
Published: November 2012

A 10-month-old, 580 kg, hand-reared white rhinoceros (Ceratotherium simum) calf was presented for emergency exploratory celiotomy. Anaesthesia was safely induced with three successive intravenous (IV) boluses of diazepam (10 mg) and ketamine (100 mg) until the trachea could be intubated. Anaesthesia was adequately maintained with isoflurane-inoxygen (mean end-tidal isoflurane concentration of 1.1% ± 0.2%) on a circle anaesthetic machine with carbon dioxide absorption and an intravenous infusion of ketamine and medetomidine at a mean rate of 0.02 mg/kg/min and 0.02 µg/kg/min, respectively. Mean values recorded during anaesthesia and surgery were heart rate (56.9 ± 11 beats/min), mean arterial blood pressure (6.16 kPa ± 1.75 kPa), end-tidal carbon dioxide concentration (6.23 kPa ± 0.30 kPa). Abdominal gas distension contributed to hypoventilation that resulted in hypercapnoea, confirmed by arterial blood gas analysis (PaCO2 14.69 kPa), which required controlled ventilation for correction. Blood volume was maintained with the intravenous infusion of a balanced electrolyte solution at 10 mL/kg/h and blood pressure supported with a continuous infusion of dobutamine and phenylephrine. Duration of anaesthesia was 3.5 h. It was concluded that anaesthesia was safely induced in a compromised white rhinoceros calf with a combination of diazepam and ketamine. A constant-rate infusion of medetomidine and ketamine allowed for a reduction in the dose of isoflurane required during maintenance of anaesthesia and improved intra-operative blood pressure management.
Prevalence, predilection sites and pathological findings of Taenia multiceps coenuri in slaughtered goats from south-east Iran
Authors: Kheirandish Reza , Sami Masoud , Azizi Shahrzad , Mirzaei Mohammad
Published: November 2012

Coenurosis is a zoonotic disease in a variety of ruminants caused by the metacestode of Taenia multiceps. The coenuri in the brain and spinal cord of sheep and goats have been identified as Coenurus cerebralis whilst those reported in other tissues have been named Coenurus gaigeri. This study was conducted during the spring and summer of 2011. Out of 25 739 goats inspected in slaughterhouses, 23 carcasses (0.09%) revealed one or multiple visible swellings on the different muscles and visceral organs. The coenuri, of variable sizes, were found mainly in the muscles of the thigh, shoulder and neck, and were less common in the abdominal muscles and subcutaneous tissues. Coenuri were also found in the diaphragm, tongue, intercostal muscles, lung, parotid area and tunica adventitia of the aorta in a goat with severe infection. The brains of slaughtered goats that had coenuri in their skeletal muscles were examined and coenuri were found in two specimens (8.69%). The coenuri were located in the occipital lobe, the anterior part of the right cerebrum and the parietal lobe of the left cerebrum. Histopathologically, coenuri in the brain caused pressure atrophy and liquefactive necrosis in the surrounding tissues, hyperaemia, perivascular cuffing, neuronal degeneration, neuronophagia, satellitosis, diffuse microgliosis and astrocytosis. Coenuri in the skeletal muscles caused degenerative and necrotic changes, hyalinisation and myositis. In the lung, tissues around the coenurus revealed atelectasis and focal interstitial fibrosis. In the present study, concurrent occurrence of coenuri in the central nervous system and skeletal muscles supports the hypothesis that C. cerebralis and C. gaigeri are different names for the metacestodes of the same species of tapeworm.
The development of mathematical creativity through model-eliciting activities
Authors: Wessels Helena M.
Published: November 2012

The ability to think creatively and solve problems is regarded as crucial for economic and personal success. The traditional approach in classrooms is not conducive to mathematical creativity, and prospective teachers should be exposed to alternative problem solving activities through which mathematical knowledge, competencies and creativity can be developed. Research studies have pointed out the possibilities and successes of a modelling approach in which complex, open problems or model-eliciting problems are used to develop meaningful mathematical knowledge and prepare learners for everyday life, as well as for tertiary studies and their occupations. Model-eliciting activities (MEAs) do not only develop mathematical knowledge, but also creativity. Five hundred and one preservice Foundation Phase teachers completed different model-eliciting activities (MEAs) in a longitudinal project over a period of two years. The purpose was to develop and consolidate their own mathematical knowledge, and at the same time develop creativity and modelling competencies. The ultimate purpose of the project is to prepare preservice teachers to use mathematical modelling to develop creativity in young children aged six to nine. Through solving MEAs learners also build and consolidate their mathematical knowledge and improve their own problem-solving abilities. A framework with four criteria for the identification of creativity was successfully used to evaluate levels of creativity in the solutions offered to the MEAs. Preservice teachers’ final models displayed reasonably consistent levels of creativity regarding the four criteria. Their willingness to solve MEAs and create multiple, original and useful – therefore creative – solutions also increased over the period of their exposure to modelling tasks.
Comparison of the Protective Effects of Radix Astragali, α-Lipoic Acid, and Vitamin E on Acute Acoustic Trauma
Authors: Xiong Min , Lai Huangwen , Yang Chuanhong , Huang Weiyi , Wang Jian , Fu Xiaoyan , He Qinglian
Published: November 2012

Objective

Oxidative damage is a critical role which involves hearing loss induced by impulse noise. That exogenous antioxidant agents reduce noise induced hearing loss (NIHL) has been well demonstrated in both animal studies and clinical practices. Choosing a stronger and more effective antioxidant is very important for treatment of NIHL. Vitamin E, α-lipoic acid, and radix astragali are the most commonly used anti-oxidants for cochlear oxidative damage from acoustic trauma. In this study, the protective effects of radix astragali, α-lipoic acid, and vitamin E on acute acoustic trauma are investigated.

Methods

Guinea pigs in the experimental groups were intragastrically administered vitamin E, α-lipoic acid, and radix astragali. Auditory thresholds were assessed by sound-evoked auditory brainstem response (ABR) at click and tone bursts of 8, 16 and 32 kHz, 24 hours before and 72 hours after exposure to impulse noise. Cochlear malondialdehyde (MDA) concentrations were detected. Hair cell damage was analyzed by scanning electron microscopy.

Results

Vitamin E, α-lipoic acid, and radix astragali significantly reduced ABR deficits, reduced hair cell damage, and decreased the concentrations of MDA. α-lipoic acid and radix astragali were better than vitamin E, and there were no significant differences between α-lipoic acid and radix astragali.

Conclusions

α-lipoic acid or radix astragali are recommended for treatment of NIHL.
Challenges of Managing Advanced Cancer Patients through Phone Triaging at an Outpatient Supportive Care Clinic: A Case Series of Palliative Care Patients
Authors: Pimentel Lindsey E. , Yennurajalingam Sriram , Brown Elizabeth D. , Castro Debra K.
Published: November 2012

Palliative care strives to improve the quality of life for patients and their families by impeccable assessment and management using an interdisciplinary approach. However, patients with cancer-related pain and other symptoms tend to be undertreated because of limited follow-up visits due to late referrals and logistics. Thus, patients who present to the outpatient Supportive Care Center at The University of Texas MD Anderson Cancer Center often experience severe physical and psychological symptoms. The two case reports presented highlight the challenges of managing distressed patients with advanced cancer in the outpatient setting. These descriptions focus on addressing patient needs over the phone to enhance the care patients receive at the Supportive Care Center. Future prospective studies are needed to measure the effectiveness of using phone triaging in conjunction with standard outpatient palliative care.
An Esthetic Treatment Outcome of Orthognathic Surgery and Dentofacial Orthopedics in Class II Treatment: A Cephalometric Study
Authors: Kabbur Karthik Jayadevappa , Hemanth M , Patil GS , Sathyadeep V , Shamnur Naveen , Harieesha KB , Praveen GR
Published: November 2012

Aim

The main objective of any orthodontic treatment is to achieve well-established stable occlusal relationship with a definite positive change in facial profile. The purpose of this study was to determine, if such a goal is achievable for patients who could be classified as borderline surgical cases without the invasive use of the actual surgery or, with the use of the recently developed and rapidly spreading fixed functional appliance system (Forsus) and a comparison of the esthetic treatment outcome with the two systems.

Materials and methods

Twelve postadolescent borderline skeletal class II patients with a deficient mandible. All the patients used in the study were treated by a preadjusted edgewise appliance for presurgical decompensation with or without extractions and for postsurgical finishing and detailing. Out of the 12 patients six were treated with bilateral saggital split osteotomy (BSSO) and six were treated with fixed functional appliance (Forsus).

Results

The results suggested that although surgical patients had a better mandibular advancement, profile reduction, and marked improvements in soft tissue structures, the patients who had undergone fixed functional therapy also had comparable improvement in the above aspects. In the maxilla there was no change in cases treated with surgery but in case of Forsus some retraction of anterior dental segment was evident.

Conclusion

In surgical group, class II malocclusion correction was more skeletal than dental, whereas in functional group class II malocclusion correction was more dental than skeletal.

Clinical significance

Looking at the common surgical risks, cost-effective and postsurgical problems and patients with borderline class II malocclusion, fixed functional therapy is a valuable adjunct in the management of class II malocclusion.

How to cite this article

Kabbur KJ, Hemanth M, Patil GS, Sathyadeep V, Shamnur N, Harieesha KB, Praveen GR. An Esthetic Treatment Outcome of Orthognathic Surgery and Dentofacial Orthopedics in Class II Treatment: A Cephalometric Study. J Contemp Dent Pract 2012;13(5):602-606.
Comparative Evaluation of Effectiveness of Sodium Dichloroisocyanurate and Calcium Hydroxide against Candida albicans
Authors: Kurian Jacob , Bolla Nagesh , Damaraju Bhargavi
Published: November 2012

Introduction

Candida albicans is the most commonly isolated fungi from the oral cavity. It is the most infective to various intracanal medicaments and is considered as invasive yeast. Sodium dichloroisocyanurate (NaDCC) which is used as a disinfectant and as a biocide in treating potable water has similar action to that of sodium hypochlorite against microbes. The aim of the present study is to compare the effectiveness of calcium hydroxide and NaDCC against Candida albicans.

Materials and methods

After obtaining the stock cultures of Candida, the isolates were divided into six groups which were exposed to different concentrations of NaDCC and calcium hydroxide Ca(OH)2. Group 1 consisted of the isolates which were subdivided into three groups, subjected to three different concentrations of NaDCC. Group 2 also consisted of three subgroups exposed to three different concentrations of Ca(OH)2. Group three consisted of three subgroups which were exposed to three different concentrations of combinations of both NaDCC and Ca(OH)2.

Results

The results of the present study show that calcium hydroxide was totally ineffective at all concentrations and NaDCC was effective and also the combination of both was shown to be effective.

Conclusion

NaDCC alone was effective at all concentrations and the combination with Ca(OH)2 was found to be less effective. Ca(OH)2 was totally ineffective.

How to cite this article

Kurian J, Bolla N, Damaraju B. Comparative Evaluation of Effectiveness of Sodium Dichloroisocyanurate and Calcium Hydroxide against Candida Albicans. J Contemp Dent Pract 2012;13(5):665-670.
Meckel-Gruber Syndrome (Dysencephalia Splanchnocystica)
Authors: Shetty B Prasanna , Alva Nandakishore
Published: November 2012

Meckel-Gruber syndrome is a rare lethal autosomal recessive condition which was first described by Johann Friedrich Meckel in 18221 and GB Gruber in 1934.2 More than 200 cases have been reported worldwide with an incidence ranging from 1:13,250 to 1:140,000 live births.3

A 21-year-old female with G3 A2 L0, presented with twin pregnancy with history of previous two anencephalic pregnancies. The present pregnancy was a preterm vaginal delivery of female twins by face presentation at 35 weeks of gestation (diamniotic dichorionic twin gestation).

Neonatal autopsy revealed classical triad of occipital encephalocele, polycystic kidneys and lungs with postaxial polydactyly.

This case is presented for its rarity and its documented occurrence in Gujarati Indians.

How to cite this article

Shetty BP, Alva N, Patil S, Shetty R. Meckel- Gruber Syndrome (Dysencephalia Splanchnocystica). J Contemp Dent Pract 2012;13(5):713-715.
Are Current Account Deficits Sustainable? New Evidence from Iran Using Bounds Testing Approach to Level Relationships
Authors: Heidari Hassan , Katircioglu Salih Turan , Davoudi Narmin
Published: November 2012

This paper provides new evidence on the long-run relationship between exports and imports of the Iranian economy by employing bounds testing approach to level relationships. In Iran, there have been many unusual policy changes and/or external shocks to the economy; this has resulted in the occurrence of a multitude of structural breaks in macroeconomic variables. By taking these breaks into account, results of the present study reveal that there is a long-run equilibrium relationship between imports and exports over the sample period, 1960–2007. This result confirms the finding of Arize (Imports and exports in 50 countries: Tests of cointegration and structural breaks, 2002) by employing bounds tests to level relationships and suggests that current account deficits in Iran are sustainable.
Calibration of the SBUV version 8.6 ozone data product
Authors: DeLand M. T. , Taylor S. L. , Huang L. K. , Fisher B. L.
Published: November 2012

Abstract. This paper describes the calibration process for the Solar Backscatter Ultraviolet (SBUV) Version 8.6 (V8.6) ozone data product. Eight SBUV instruments have flown on NASA and NOAA satellites since 1970, and a continuous data record is available since November 1978. The accuracy of ozone trends determined from these data depends on the calibration and long-term characterization of each instrument. V8.6 calibration adjustments are determined at the radiance level, and do not rely on comparison of retrieved ozone products with other instruments. The primary SBUV instrument characterization is based on prelaunch laboratory tests and dedicated on-orbit calibration measurements. We supplement these results with "soft" calibration techniques using carefully chosen subsets of radiance data and information from the retrieval algorithm output to validate each instrument's calibration. The estimated long-term uncertainty in albedo is approximately ±0.8–1.2% (1σ) for most of the instruments. The overlap between these instruments and the Shuttle SBUV (SSBUV) data allows us to intercalibrate the SBUV instruments to produce a coherent V8.6 data set covering more than 32 yr. The estimated long-term uncertainty in albedo is less than 3% over this period.
XCO2-measurements with a tabletop FTS using solar absorption spectroscopy
Authors: Gisi M. , Hase F. , Dohe S. , Blumenstock T. , Simon A. , Keens A.
Published: November 2012

Abstract. A commercial low-resolution (0.5 cm−1) Fourier Transform Spectrometer (FTS) has been modified and is used for determining the total column XCO2 of the atmosphere by analysing direct solar radiation. The spectrometer has a small home-built solar tracker attached, so that it is a ready-to-use instrument. The results are validated with temporally coinciding on-site measurements taken with a high-resolution Total Carbon Column Observing Network (TCCON) FTIR spectrometer. For the whole comparison period of 5 months (26 measurement days) an agreement with TCCON results of (0.12 ± 0.08)% is achieved. This makes the spectrometer a promising candidate for a low-cost addition to the TCCON core FTIR sites, especially suitable for locations with limited infrastructure. An impressive mechanical and thermal stability is proved, enabling the spectrometer for use in field campaigns and for the monitoring of local sources.
Improved water vapour spectroscopy in the 4174–4300 cm−1 region and its impact on SCIAMACHY HDO/H2O measurements
Authors: Scheepmaker R. A. , Frankenberg C. , Galli A. , Butz A. , Schrijver H. , Deutscher N. M. , Wunch D. , Warneke T. , Fally S. , Aben I.
Published: November 2012

Abstract. The relative abundance of the heavy water isotopologue HDO provides a deeper insight in the atmospheric hydrological cycle. The SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) allows global retrievals of the ratio HDO/H2O in the 2.3 micron wavelength range. However, the spectroscopy of water lines in this region remains a large source of uncertainty for these retrievals. We therefore evaluate and improve the water spectroscopy in the range 4174–4300 cm−1 and test if this reduces systematic uncertainties in the SCIAMACHY retrievals of HDO/H2O. We use a laboratory spectrum of water vapour to fit line intensity, air broadening and wavelength shift parameters. The improved spectroscopy is tested on a series of ground-based high resolution FTS spectra as well as on SCIAMACHY retrievals of H2O and the ratio HDO/H2O. We find that the improved spectroscopy leads to lower residuals in the FTS spectra compared to HITRAN 2008 and Jenouvrier et al. (2007) spectroscopy and the retrievals become more robust against changes in retrieval window. For both the FTS and SCIAMACHY measurements the retrieved total columns H2O decrease by 2–4 % and we find a negative shift of the HDO/H2O ratio, which for SCIAMACHY is partly compensated by changes in the retrieval setup and calibration software. The updated SCIAMACHY HDO/H2O product shows somewhat steeper latitudinal and temporal gradients and a steeper Rayleigh distillation curve, strengthening previous conclusions that current isotope-enabled general circulation models underestimate the variability in the near-surface HDO/H2O ratio.