bluuebunny/crossref_metadata_2025 huggingface dataset:
Local Probes in Magnetic Semiconductors – PAC Investigations
Authors: Samokhvalov Vyacheslav , Richter Andreas , Degering Detlev , Unterricker Sepp , Dietrich Marc , Deicher Manfred , Tiginyanu Ivan M. , Isolde-Collaboration the
Published: March 2014

Magnetic and electric hyperfine interactions in the magnetic semiconductor CdCr2Se4 are measured using 111mCd and 111In(111Cd) PAC. The radioactive probes were implanted. In-probes occupy predominantly the Cr-site, but a part of them is also substituted at the Cd-site. This is proved by the measured internal fields. Theoretical hyperfine fields are calculated by the WIEN97-code.
Dimensional and Chemical Control of Colossal Magnetoresistance in New Manganites
Authors: Liu Ru-Shi , Shen Chih-Hung , Hu Shu-Fen , Lin Jauyn Grace , Huang Chao-Yuan
Published: March 2014

The effects of structural, electrical and magnetic properties with the isovalent chemical substitution of Ca2+ into the Sr2+ sites in new series of two-dimensional La1.2(Sr1.8-xCa
x
)Mn2O7 compounds (x=0∼0.8) and three-dimensional La0.6(Sr0.4-xCax)MnO3 compounds (x=0∼0.4) are investigated. The Curie temperatures (T
C
) decreased from 135 K to 102 K and 370 K to 270 K for x = 0 to 0.4 in La1.2(Sr1.8-xCax)Mn2O7 and La0.6(Sr0.4-xCax)MnO3, respectively. The antiferromagnetic behavior with Néel temperature around 30 K was found in the x=0.8 sample in La1.2(Sr1.8-xCax)Mn2O7. The composition induced structural variation has been found in La0.6(Sr0.4-xCax)MnO3. All the results demonstrate that the dimensionality and chemical size play an important role in controlling the colossal magnetoresistance in manganites.
Optical and Electrical Properties of Microwave Dielectric Thin Films
Authors: Chen Yi-Chun , Cheng Hsiu-Fung , Lin I-Nan
Published: March 2014

The dielectric properties of ceramics and thin films of Bi2(Zn1/3Nb2/3)2O7, BiZN, materials were examined in low frequency (1 kHz – 3 MHz), microwave frequency (0.5 – 10 GHz) and optical frequency (4×1011–7×1011 kHz) regimes. The dielectric properties in the optical frequency regime, (ε

r
)
o
p
\cong4.9–6.5, are insensitive to the material characteristics, implying that only the electronic polarization is functioning in this frequency regime. By contrast, the properties in the low frequency regime, (ε

r
)
l
f
\cong160–300, are markedly influenced by the synthesis parameters, indicating that the dielectric properties in this regime are predominated by the ionic polarization process. Therefore, these properties vary with the crystallinity of the materials.
Optimization of Deposition Conditions of SrBi2Ta2O9 Thin Films in Radio-Frequency Magnetron Sputtering
Authors: Chen Yi-Chou , Lu Chung-Hsin
Published: March 2014

SrBi2Ta2O9 thin films were fabricated on Pt/Ti/SiO2/Si substrates at various sputtering pressure and target-to-substrate distance using radio-frequency magnetron sputtering in this study. The compositions of the deposited films significantly vary with sputtering pressure and target-to-substrate distance. Both strontium and bismuth contents decrease with increasing the process pressure; however, only bismuth content increases with the target-to-substrate distance. The sputtering pressure and target-to-substrate distance also affect the electrical properties. The leakage current of prepared films increases not only with an increase in the target-to-substrate distance, but also with a decrease in the sputtering pressure. The remanent polarization value (2Pr) of SBT films deposited under 100 mtorr at the target-to-substrate distances of 3 cm is 5.3 µC/cm2, and no significant fatigue is found after 109 switching cycles.
Crystal Growth and Characterization in the System (Ga1-xInx)2O3
Authors: Tomm Yvonne , Ko Jung Min , Yoshikawa Akira , Sugawara Takamasa , Fukuda Tsuguo
Published: March 2014

We have grown (Ga1-xInx)2O3 mixed crystals by the floating zone technique. The unit cell size of the mixed crystal increases with increasing In content according to Vegards law. For 50 mol% In2O3 we obtained single crystals of a structure different from the regular monoclinic one. Slightly doped (Ga1-xInx)2O3 crystals show n-type semiconduction. With increasing In content, the crystals became p-type semiconductors.
Structure and Magnetic Properties of Fe/Si Multilayers
Authors: Chen Wei-Chuan , Lai Chih-Huang , Lee Shang-Fan , Liou Yung , Yao Yeong-Der
Published: March 2014

Fe/Si multilayers have been grown on MgO(100) and Si(100) substrates by dc magnetron sputtering. From x-ray diffraction analysis, the Fe(100) orientation was dominated in samples with MgO(100) as substrates, and the Fe(110) orientation was dominated in samples with Si(100) as substrates. Ferromagnetic coupling was observed for samples with Si spacer thickness greater than 17 Å or less than 11 Å, and antiferromagnetic coupling occurred for samples with Si spacer thickness between 11 Å and 17 Å. The strength of antiferromagnetic coupling was stronger in samples on MgO. This indicated that the magnetic coupling between Fe layers may be closely related to the structural orientation of the magnetic layers. For the Fe 60Å/Si 13Å/Fe 60 Å trilayer on the MgO(100) substrate, Mr/Ms was equal to 0.3, however, it increased to 0.95 on Si (100).
Cu-Substitution Effect on a Square-Planar CoO2 Layer in a New Layered Transition-Metal Oxysulfide Sr2Cu2CoO2S2
Authors: Matoba Masanori , Okada Satoshi , Fukumoto Satoshi , Soyano Shunji , Kitô Hijiri
Published: March 2014

The synthesis and characterization of Sr2Cu2Co1-xCuxO2S2 (x ≤ 0.5) are reported. Cu 2p x-ray photoelectron spectroscopic (XPS) spectra with no clear satellite indicates that the Cu ion is not in the “Cu2+” state but in the “Cu+” state. Co 2p XPS spectra with a strong satellite were analyzed by the configuration interaction CoO4 cluster model, suggesting that the samples belong to a strongly correlated electron system such as high-T

C
superconductors. The samples with x<0.4 shows a semiconducting behavior, while the samples with x=0.4 and x=0.5 exhibits a metal-semiconductor transition at 200K and 175K, respectively.
Crystal Growth of High Purity AgIn(SxSe1-x)2 Single Crystals
Authors: Yoshino Kenji , Mitani Naoji , Sugiyama Mutsumi , Chichibu Shigefusa , Nakanishi Hisayuki , Ikari Tetsuo
Published: March 2014

The AgIn(SxSe1-x)2 (X=0 ∼ 1.0) crystals are grown by a normal freezing (NF) method. All samples indicate chalcopyrite structures and n-types by means of X-ray diffraction (XRD) and thermoprobe analysis, respectively. Lattice constants a and c are found to be proportional X, according to Vegard's law. In the AgIn(S0.25Se0.75)2 sample, free exciton (FE) emission line is clearly observed in the photoluminescence (PL) spectrum at 77 K for the first time.
Effect of Reactants on the Electrical Properties of Sol-Gel Derived PZT Thin Films
Authors: Lu Hsin-Chun , Wu Chun-Hsien , Chou Shean-Dar
Published: March 2014

Precursor solutions of lead zirconium titanates were prepared by mixing lead acetate with different combinations of zirconium and titanium alkoxides in a solvent composing of acetic acid and 2-methoxyethanol. PZT thin films were deposited on Pt/Ti/SiO2/Si substrates by spin coating and sintered at temperatures above 400°C. It was found that the crystallization behaviors and the electrical properties showed marked differences for PZT thin films prepared by different reactants. The PZT thin films prepared by the Pb(OAc)2-Zr(OPr)4-Ti(OPri)4 system exhibited superior electrical properties compared with those prepared by other combinations of reactants including the normally used Pb(OAc)2-Zr(OPri)4-Ti(OPri)4 system, which indicates that the selection of reactants has crucial impact on the electrical properties of sol-gel derived PZT thin films.
Low-Field Magnetoresistance in La-Ca-Mn-O Films with Al2O3 Addition by D.C. Sputtering
Authors: Chen Li-Han , Chu Chi-Wen , Chou Chi-Yu , Lee Chien-Liang
Published: March 2014

The La0.67Ca0.33MnO3-x films doped with Al2O3 up to 25 at% have been grown on the (100)LaAlO3 substrates at 400 C by a d.c. magnetron sputtering process. The sputtered films have a polycrystalline structure, which shows a [100] preferential orientation. An Al2O3-rich second phase exists in the microstructure of films doped with Al2O3 more than 5%. It is found that the MR behavior of films is strongly influenced by the Al2O3 doping and annealing treatment. The film doped with 5% Al2O3, deposited at 400 C and annealed at 1000 C for 4 hr, shows a MR ratio as high as ∼4980% at 100 K and at 8 kOe which corresponds to a MR sensitivity of ∼0.6%/Oe. Such a huge low-field MR behavior can be ascribed to the spin-polarized tunneling across grain boundaries where an Al2O3-rich second phase is believed to exist.
Distribution of Easy-Axis of Magnetoplumbite Particles in Magnetic Recording Media and Rubber Magnets
Authors: Kohmoto Osamu , Kubo Osamu , Miyoshi Junji
Published: March 2014

The strong c-axis orientation in the magnet was observed by distribution function (f(0)=7.2) and X-ray diffraction. The orientation in the media (f(0)=3.9) is slightly worse than that in the magnet, which is consistent with XRD results.
Electrical and magnetic properties of LnRu4P12(Ln = Nd, Gd and Tb) with filled skutterudite structure
Authors: Uchiumi Takanori , Sekine Chihiro , Shirotani Ichimin
Published: March 2014

We have prepared LnRu4P12(Ln = Nd, Gd and Tb) with filled skutterudite structure at high temperatures and high pressures. GdRu4P12 and TbRu4P12 are new materials. Electrical resistivity and dc magnetic susceptibility of these compounds were measured at low temperatures. NdRu4P12 behaves as a metal, showing ferromagnetic ordering below 1.6 K. GdRu4P12 and TbRu4P12 show electrical anomalies and antiferromagnetic transitions at around 20 K. Electrical anomalies of both compounds are closely related to the magnetic transitions.
Superconductivity of ternary equiatomic compounds with Tc of above 10 K
Authors: Shirotani Ichimin , Konno Yuji , Kato Daisuke , Sekine Chihiro , Todo Sakae , Yaagi Takehiko
Published: March 2014

Equiatomic compounds HfRuP, ZrRuP, ZrRuAs, ZrRuSi, ZrRuGe, ZrRhSi and NbPS having the valence electrons per formula unit of 16 or 17 were prepared at high temperatures and high pressures. Electrical and magnetic properties of the compounds have been studied at low temperatures. These compounds show the superconducting transition above 10 K. The upper critical fields(Hc2's) of HfRuP, ZrRuX(X = P, As, Si and Ge) and NbPS are 14, 16, 14.1, 14.5, 8.3 and 17 tesla(T) at 0 K, respectively. The Hc2 of NbPS is highest among the equiatomic compounds.
Effects of Cooling Rate on Growth of Bi-2212 Superconducting Whiskers
Authors: Tei Minaru , Manmoto Yoshinori , Yoshimochi Tomohiro , Nobori Masaki
Published: March 2014

Bi2Sr2CaCu2Ox (Bi-2212) superconducting whiskers have been prepared by using a melt-quenched glass precursor method and it has been reported that the glass precursor was necessary to the growth of the long whiskers. In this work to ascertain the necessity, the effects of the cooling rate of the melt on the growth of Bi-2212 whiskers were studied. Our experimental results indicated that the glass precursors were not needed for the whisker growth. In addition we report that long YBa2Cu3Ox whiskers of 1∼3 mm in length can be prepared by melting and furnace cooling.
Controlling Defect Structure and Properties of Complex Thermoelectric Materials
Authors: Rogacheva Elena
Published: March 2014

Some common problems connected with coexistence of point defects induced both by doping and deviation from stoichiometry in ternary semiconductor phases have been considered in connection with their thermoelectric applications. The original results have been presented. The method of controlled atomic defects has been developed and applied to ternary systems (Sn-In-Te, Ge-In-Te, Sn-Sb-Te, Cu-In-Se, etc.) for optimizing thermoelectric properties. It has been shown that critical phenomena of percolation nature observed in the range of small concentrations of impurity or intrinsic defects should be taken into account when developing thermoelectric materials. The role of long- and short-range ordering has been considered. Some specific phenomena occurring under introduction of impurities of variable valence have been pointed out.
Negative Thermal Expansion Materials
Authors: Evans John S. O.
Published: March 2014

The ZrW2O8 family of materials has been shown to exhibit the unusual property of negative thermal expansion over a wide temperature range. α-ZrW2O8 itself shows negative thermal expansion from 2 K to 1443 K with a coefficient of thermal expansion α1 of -9.1×10-6 K-1 between 2 and 300 K. This behaviour can be related to the unusual structure of these materials, which possess a family of low energy phonon modes with negative Gruneisen parameters. α-ZrW2O8 also shows a phase transition at 448 K to β-ZrW2O8 in which oxygen atoms are dynamically disordered. These phenomena have been investigated by a number of techniques. Results of powder neutron diffraction at 260 different temperatures are presented.
THM Growth of Bulk CuInTe2 Single Crystals from In Solution
Authors: Miyake Hideto , Hibi Masanori , Sugiyama Koichi , Hiramatsu Kazumasa
Published: March 2014

Phase relations in the CuInTe2-In pseudobinary system have been investigated. There exists a miscibility gap in the liquid phase, but the saturated In solutions at temperature over 550°C were confirmed to be single-phase liquid, from which chalcopyrite CuInTe2 crystals can be grown. On the basis of the phase diagrams, THM growth of CuInTe2 crystals was performed.
Structural and Physical Characterization of Erbium-doped TiO2-based Planar Waveguide Amplifiers
Authors: Ting Chu-Chi , Li Chia-Hou , San-Yuan Chen San-Yuan Chen
Published: March 2014

The TiO2-Y2O3 systems can offer the densified host matrix with a controllable refractive index ranging from 2.1 to 2.3. Sol-gel method is used to synthesize the erbium-doped TiO2-based Y2O3 precursor solution in this work. It was found that higher Y3+-doped concentration will reduce the refractive index of composite films. When Er2O3 additive was more than 10 mol%, Er3+ ions cluster effect reduced the photoluminescence (PL) intensities in erbium-doped TiO2-Y2O3 films. Furthermore, with increasing Y2O3 addition, an amorphous matrix was formed and enhanced the efficiency of PL.
Fluorescence Properties of Sol-gel Derived Er3+-doped TiO2-Al2O3 Composite Thin Films
Authors: Ting Chu-Chi , Li Chia-Hou , Chen San-Yuan
Published: March 2014

The photoluminescence (PL) emission from the first excited state (4I13/2) to the ground state (4I15/2) in Er3+ occurs at the wavelength 1.54 µ m, a standard telecommunication wavelength of silica-based optical fibers. Both PL intensity and FWHM spectral width will increase with more Er3+ doping. In the present study, the sol-gel spin coating process was used to prepare the Er3+-doped TiO2-Al2O3 composite thin films. With increasing Al2O3 content, the phase transformation of amorphous to anatase states was delayed in the composite films. The incorporation of Er3+ ions reduces the amount of aluminum sites in the 4-fold coordination and increases the 5-fold coordination. Furthermore, it was found that the PL intensity could be enhanced with the increasing of Al2O3 addition in the Er+3-doped TiO2-Al2O3 composite films.
A study of deep levels in bulk CuInSe2 grown by THM METHOD
Authors: Yoneta Minoru , Miyake Hideto , Yoshino Kenji , Hiramatsu Kazumasa , Ikari Tetsuo , Ohishi Masakazu , Saito Hiroshi
Published: March 2014

We have found with deep level transient spectroscopy (DLTS) measurement two hole traps with a thermal activation energy of 0.20eV and 0.48eV in Se-annealed CuInSe2 grown by a travel heater method (THM). The applications of a reverse and a forward bias under cooling the sample for DLTS cause an increase and a decrease of the trap density of 0.20eV hole trap. It suggests the 0.20eV trap is a metastable defect, the charge state of the trap changes by applying an electric field at low temperature region(<300K). On the other hand, the 0.48eV trap density hardly changed by applying any bias voltages under the cooling process. Moreover, the two hole traps annihilated after long annealing at room temperature. Defect reaction model is proposed to explain the results.
Solution Growth of CuGaxIn1-xSe2 from CuSe Solutions
Authors: Miyake Hideto , Ohtake Hiroyuki , Sugiyama Koichi , Hiramatsu Kazumasa
Published: March 2014

Phase relations in the CuGaxIn1-xSe2 -CuSe pseudobinary system have been investigated. The solids in equilibrium with the liquids at temperatures above 630°C are single-phase CuGaxIn1-xSe2 with chalcopyrite structure, but those at temperatures below 610°C are composed of two phases of CuGaxIn1-xSe2 and CuGa2-xSe. The relation between the composition of the grown crystal and that of the solute in the CuSe solutions was determined for the 10 mol% CuSe solutions. On the basis of the phase diagrams, THM growth of CuInSe2 and CuGaxIn1-xSe2 crystals was performed.
CuInSe2 Monograin Growth in CuSe-Se Liquid Phase
Authors: Altosaar Mare , Mellikov Enn
Published: March 2014

Isothermal growth of CuInSe2 monograin powders in molten CuSe-Se flux has been studied proceeding from Culn (1:1) alloy, Se and CuSe. The activation energy for linear crystal growth Ed = 0.28(±0.03) eV and the power of time dependence of crystal growth 1/n=0.27(±0.017) according to the equation: dm=At1/nexp
(-Ed/kT) have been found. As a result homogeneous high-conductive (0.5 Ωcm) p-type CuInSe2 material (22.4 : 25.1 : 52.5) with single-crystalline grain structure and narrow-disperse granularity is synthesized from CuSe-Se solvent.
Single crystal growth of SrGa2S4 by the self-flux method
Authors: Komatsu-Hidaka Chiharu , Takizawa Takeo
Published: March 2014

We have grown single crystals of SrGa2S4:Ce3+ by the self-flux method using Ga2S3 as a flux. Single crystals with different cerium concentrations have been also prepared. Photoluminescence spectra of these crystals are measured under the excitation of 325 nm light from He-Cd laser at room temperature.
Weight - Loss Measurements for CdB4As2 - Vapour Systems
Authors: Voevodin Valery , Voevodina Olga , Bereznaja Svetlana , Korotchenko Zoya
Published: March 2014

The quantity of material in vapour phase was defined by the weight-loss measurements. Two models of dissociation of CdGeAs2 and CdSnAs2 were considered. The models were based on condition of incongruent evaporation Model 1 and 2 called for absence or existence of Cd3As2 formation in gas phase. Corresponding sets of simultaneous equations were solved. The analyses of the results were carried out. An attempt to estimate the thermodynamic parameters of the compounds and values of total and partial equilibrium pressures at the melting point and lower temperatures was made.
Band gap of the filled-tetrahedral semiconductor LiMgP evaluated by photoacoustic spectroscopy
Authors: Kushida Kazumasa , Kuriyama Kazuo
Published: March 2014

The filled tetrahedral semiconductor LiMgP(space group: F4̄3m) can be viewed as a hypothetical zinc-blende (MgP)- lattice partially filled with He-like Li+ interstitials, which has been found to be a direct wide-gap material with 2.43 eV at room temperature (2.535 eV at 15 K) using optical absorption and photoluminescence methods. In the present study the band gap of LiMgP was confirmed to be 2.41 eV by a photoacoustic spectroscopy. This value is close to the optical band gap.
Physics and Chemistry in Physical Vapor Deposition of Cu(In,Ga)Se2 Thin Films
Authors: Wada T. , Nishiwaki S. , Kohara N. , Negami T. , Niki S. , Suzuki R. , Ohdaira T. , Ishibashi S. , Yamada A.
Published: March 2014

Growth of Cu(In,Ga)Se2 (CIGS) thin films during the physical vapor deposition (PVD) were characterized by scanning Auger electron spectroscopy (SAES), secondary ion mass spectroscopy (SIMS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The deposition processes are comparable with the 2nd and 3rd stages of the “3-stage” process. The phase changes observed in CIGS films during the 2nd stage of the “3-stage” process were as follows: (In,Ga)2Se3 → [Cu(In,Ga)5Se8] → Cu(In,Ga)3Se5 → Cu(In,Ga)Se2. The grain size increased from the sub-micron grains of the (In,Ga)2Se3 precursor film to several micrometers in the stoichiometric Cu(In,Ga)Se2 film. Growth mechanism of CIGS crystal are discussed on the basis of the phase diagram of the Cu2Se-In2Se3 pseudo-binary system, and crystal structures and stacking sequences of Se atomic layers of compounds in the In2Se3–Cu2Se system.
Low Temperature Resonant Raman Scattering in AgGaSe2
Authors: Yamamoto Nobuyuki , Huang Wen-Zheng , Wakita Kazuki
Published: March 2014

Low temperature resonant Raman spectra of AgGaSe2 have been investigated in the wide range of excitation photon energy, 1.74 eV-1.93 eV. In the absorption range (≥1.80 eV), a strong outgoing resonance effect mediated by free exciton has been observed, whereas a week incoming resonance enhanced by donor-acceptor pair emission has appeared in the transmission range (≤1.77 eV). Selection rules in the usual Raman tensor were almost broken down and, over the whole excitation energy range, the dipole optical selection rule between the uppermost “A” balance band and the conduction band seemed to dominate.
Temperature Dependence of Resonant Raman Scattering in AgGaS2 Crystals
Authors: Wakita Kazuki , Sakai Yasuhisa , Fujita Futoshi , Yamamoto Nobuyuki , Susaki Masami
Published: March 2014

Resonant Raman scattering has been examined on (112) as-grown surface of AgGaS2 crystals. Temperature dependence of intensity of phonon modes is explained by two terms; a radiative recombination probability at free exciton and a Lorentzian incoming resonance mediated by free exciton. The temperature dependence is mainly dominated by the former term in the case where crystals show extremely low radiative efficiency for free exciton which act as an intermediate state of resonant Raman.
Optical and Structural Properties of n-CuIn3Se5 Single Crystals
Authors: Arushanov Ernest , Kulyuk Leonid , Kulikova Oiga , Tezlevan Victor , Ruiz Ramón Fernández , León Máximo
Published: March 2014

Structural characterization of sample was carried out through the Laue showing a very perfect ternary symmetry and a high crystallinity. Optical absorption was investigated in CuIn3Se5 in the temperature range 85-300K. The energy gap (1.42 eV at 85K) and its temperature dependence were determined. The latter was studied by means of a three-parameter thermodynamic model and the Einstein model. The values of the band gap at zero temperature, average phonon energy, and a dimentionless constant related to the electron-phonon coupling were estimated. Band tail states were found to give rise to the absorption below the fundamental edge.
Optical Properties of Excitonic-Grade CuInSe2 Single Crystals
Authors: Mudriy Alexander V. , Yakushev Michael V. , Tomlinson Robert D. , Hill Arthur E. , Pilkington Richard D. , Bodnar Ivan V. , Viktorov Ivan A. , Gremenok Valeri F.
Published: March 2014

A number of CuInSe2 (CIS) single crystals have been studied employing photoluminescence (PL), optical reflection (OR), optical absorption (OA) and wavelength derivative reflection (WDR) techniques at temperatures from 4.2 to 300K. In the near-band-edge region the PL spectra, taken at 4.2K, had several very narrow, with full width at half maximum (FWHM) of about O.3meV, lines and two well resolved wider peaks (FWHM about O.7meV) at 1.0414eV (A) and 1.0449eV (B). These two peaks were also observed in the OR and OA spectra at the same energy. It is unambiguous evidence that these peaks are due to free excitonic states. A third exciton related peak (C) was observed in the WDR spectra at 1.2779eV. From the energy separation of the peaks A, B and C the crystal-field and spin-orbit splittings were estimated to be 5.3 and 234.7meV, respectively. The narrow lines were attributed to bound exciton radiative recombination on intrinsic defects.
Optical Properties of AgIn(SySe1-y)2
Authors: Sugiyama Mutsumi , Mitani Naoji , Yoshino Kenji , Ikari Tetsuo , Nakanishi Hisayuki , Chichibu Shigefusa F.
Published: March 2014

Liquid nitrogen temperature photoluminescence (PL) spectra were measured for the bulk AgIn(S
y
Se1-y
)2 crystals grown by normal freezing method. Although the spectra showed a predominant donor-acceptor pair emission, all samples exhibited a near-band-edge emission. The near-band-edge PL peak energy showed a nonlinear dependence on the S composition y.
On the Optical Properties of Defect-Chalcopyrite Single Crystals: The Aluminium Compounds HgAl2Se4, CdAl2Se4 and ZnAl2Se4.
Authors: Eifler Andreas , Riede Volker , Hecht Jan-David , Krauss Günter , Krämer Volker , Grill Wolfgang
Published: March 2014

Using both infrared and Raman spectroscopy all of the optical phonon modes of the materials under investigation have been observed and assigned to the irreducible representation of the point group of the crystals. The infrared reflectivity spectra of HgAl2Se4 as well as of oriented CdAl2Se4 single crystals show five well separated optical phonon modes for both directions of polarization, behaviour which is predicted by group theory for AIIBIII
2CVI
4 compounds crystallizing in space group I 4̄. ZnAl2Se4 has been found to crystallize in space group I 4̄2m with a statistical distribution of the vacancies and half the aluminium atoms at the sites 4d. In the infrared reflectivity spectra of various ZnAl2Se4 samples in comparison with HgAl2Se4 and CdAl2Se4, the low frequency mode of B symmetry is missing. The optical properties in the band gap region have been determined using polarized transmittance and reflectivity measurements and diffuse reflectivity measurements. The estimated band gap energies at room temperature are 2.20 eV, 3.05 eV and 3.30 eV for HgAl2Se4, CdAl2Se4 and ZnAl2Se4, respectively.
Sator
Authors:   Department of Folkloristics, Estonian Literary Museum, Estonia
Published: March 2014

Established more than twenty years ago, Sator, Studies in Folk Belief, Mythology and Customs is a multilingual peer-reviewed, fully open-access scholarly periodical. The publication is broadly interdisciplinary. It seeks to publish the best theoretical and empirical research across all subfields of folklore, ethnology of religion, old and new mythologies, rituality, and pays special attention to the studies of less researched Eurasian cultures and their diversity, especially the cultures of Finno- Ugric-Uralic language-speaking communities, as Estonia has a long tradition of investigating them. Sator is published as the yearbook of the Department of Folk Belief Studies of the Estonian Literary Museum, in co-operation with the Centre of Excellence in Estonian Studies, the Academic Society for Folklore Studies, the NGO Estonian Folklore Institute, with the support of the Kindered People’s Programme and the Cultural Endowment of Estonia.
Probing Peroxisome Dynamics and Biogenesis by Fluorescence Imaging
Authors: Jauregui Miluska , Kim Peter K.
Published: March 2014

Peroxisomes are the most recently discovered classical organelles, and only lately have their diverse functions been truly recognized. Peroxisomes are highly dynamic structures, changing both morphologically and in number in response to both extracellular and intracellular signals. This metabolic organelle came to prominence due to the many genetic disorders caused by defects in its biogenesis or enzymatic functions. There is now growing evidence that suggests peroxisomes are involved in lipid biosynthesis, innate immunity, redox homeostasis, and metabolite scavenging, among other functions. Therefore, it is important to have available suitable methods and techniques to visualize and quantify peroxisomes in response to various cellular signals. This unit includes a number of protocols that will enable researchers to image, qualify, and quantify peroxisome numbers and morphology—with both steady‐state and time‐lapse imaging using mammalian cells. The use of photoactivatable fluorescent proteins to detect and measure peroxisome biogenesis is also described. Altogether, the protocols described here will facilitate understanding of the dynamic changes that peroxisomes undergo in response to various cellular signals. Curr. Protoc. Cell Biol. 62:21.9.1‐21.9.20. © 2014 by John Wiley & Sons, Inc.
The fate of terrigenous dissolved organic carbon in a river‐influenced ocean margin
Authors: Fichot Cédric G. , Benner Ronald
Published: March 2014

The mineralization of terrigenous dissolved organic carbon (tDOC) discharged by rivers can impact nutrient and trace metal cycling, biological productivity, net ecosystem metabolism, and air‐sea CO2 exchange in ocean margins. However, the extreme heterogeneity of river‐influenced ocean margins represents a major challenge for quantitative assessments of tDOC transformations and thereby obscures the role of tDOC in biogeochemical cycles. Here a lignin‐based optical proxy for tDOC and a shelf‐wide mass balance approach were used to quantitatively assess the fate of tDOC discharged from the Mississippi‐Atchafalaya River System (M‐ARS) to the Louisiana shelf. The mass balance revealed that ~40% of the tDOC discharged by the M‐ARS during March 2009–2010 was mineralized to CO2 on the Louisiana shelf, with two thirds of the mineralization taking place in the mixed layer. A strong seasonality in tDOC mineralization was observed, with mineralization rates severalfold higher during summer than during winter. Independent assessments of specific mineralization processes indicated biomineralization accounted for ~94% of the tDOC mineralization on an annual basis and suggest that photochemical transformations of tDOC enhanced biomineralization by ~50% in the mixed layer. Direct photomineralization accounted for a relatively small fraction (~6%) of the tDOC mineralization on an annual basis. This quantitative assessment directly confirms that ocean margins are major sinks of the tDOC discharged by rivers and indicates that tDOC mineralization rates in the shelf mixed layer are sufficiently large to influence whether the Louisiana shelf is a net sink or source of atmospheric CO2.
Solar wind‐magnetosphere energy coupling efficiency and partitioning: HILDCAAs and preceding CIR storms during solar cycle 23
Authors: Hajra Rajkumar , Echer Ezequiel , Tsurutani Bruce T. , Gonzalez Walter D.
Published: March 2014

A quantitative study on the energetics of the solar wind‐magnetosphere‐ionosphere system during High‐Intensity, Long‐Duration, Continuous AE Activity (HILDCAA) events for solar cycle 23 (from 1995 through 2008) is presented. For all HILDCAAs, the average energy transferred to the magnetospheric/ionospheric system was ~6.3 ×1016 J, and the ram kinetic energy of the incident solar wind was ~7.1 ×1018 J. For individual HILDCAA events the coupling efficiency, defined as the ratio of the solar wind energy input to the solar wind kinetic energy, varied between 0.3% and 2.8%, with an average value of ~0.9%. The solar wind coupling efficiency for corotating interaction region (CIR)‐driven storms prior to the HILDCAA events was found to vary from ~1% to 5%, with an average value of ~2%. Both of these values are lower than the> 5% coupling efficiency noted for interplanetary coronal mass ejection (and sheath)‐driven magnetic storms. During HILDCAAs, ~67% of the solar wind energy input went into Joule heating, ~22% into auroral precipitation, and ~11% into the ring current energy. The CIR‐storm Joule heating (~49%) was noticeably less than that during HILDCAAs, while the ring current energies were comparable for the two. Joule dissipation was higher for HILDCAAs that followed CIR‐storms (88%) than for isolated HILDCAAs (~60%). Possible physical interpretations for the statistical results obtained in this paper are discussed.
In situ stress analysis in the northern Newark Basin: Implications for induced seismicity from CO2 injection
Authors: Zakharova Natalia V. , Goldberg David S.
Published: March 2014

We present detailed stress analysis in a deep well drilled in the northern Newark Rift Basin and evaluate the risk of induced seismicity for underground fluid injection at the locality. In situ stress orientation and magnitudes were estimated using quantitative analysis and modeling of borehole breakouts identified in high‐resolution wellbore images. The distribution of breakouts and natural fractures in the well suggests significant variability in orientation of the principal horizontal stresses in the depth range of 450–1450 m. Evidence from surface seismic reflection imaging indicates potential presence of faults at about 800 m and 1200 m that bound zones of distinctly different stress orientation at this locality. Stability of natural fractures and faults under injection conditions was evaluated for a range of potential stress magnitudes and the observed stress variability with depth. Shallow crust above ~800 m appears to be critically stressed under ambient conditions, and further pore pressure increase would put it at risk of frictional failure on favorably oriented fractures and faults. Deeper reservoirs, however, may allow over 10 MPa increase in pore pressure without fault reactivation due to a more relaxed state of stress. Additional in situ test data are needed to more accurately constrain the magnitude of the minimum horizontal stress in the basin and to enable a more complete assessment of the induced seismic risk from potential CO2 injection in the region.
LITHO1.0: An updated crust and lithospheric model of the Earth
Authors: Pasyanos Michael E. , Masters T. Guy , Laske Gabi , Ma Zhitu
Published: March 2014

We present the LITHO1.0 model, which is a 1° tessellated model of the crust and uppermost mantle of the Earth, extending into the upper mantle to include the lithospheric lid and underlying asthenosphere. The model is parameterized laterally by tessellated nodes and vertically as a series of geophysically identified layers, such as water, ice, sediments, crystalline crust, lithospheric lid, and asthenosphere. LITHO1.0 is created by constructing an appropriate starting model and perturbing it to fit high‐resolution surface wave dispersion maps (Love and Rayleigh, group and phase) over a wide frequency band (5–40 mHz). We examine and discuss the model with respect to key lithospheric parameters, such as average crustal velocity, crustal thickness, upper mantle velocity, and lithospheric thickness. We then compare the constructed model to those from a number of select studies at regional and global scales and find general consistency. It appears that LITHO1.0 represents a reasonable starting model of the Earth's shallow structure (crust and uppermost mantle) for the purposes in which these models are used, such as traveltime tomography or in efforts to create a 3‐D reference Earth model. The model matches surface wave dispersion over a frequency band wider than the band used in the inversion. There are several avenues for improving the model in the future by including attenuation and anisotropy, as well as making use of surface waves at higher frequency.
The origin and evolution of the Peace Vallis fan system that drains to the Curiosity landing area, Gale Crater, Mars
Authors: Palucis Marisa C. , Dietrich William E. , Hayes Alexander G. , Williams Rebecca M. E. , Gupta Sanjeev , Mangold Nicholas , Newsom Horton , Hardgrove Craig , Calef Fred , Sumner Dawn Y.
Published: March 2014

The landing site for the Curiosity rover is located at the distal end of the Peace Vallis fan in Gale Crater. Peace Vallis fan covers 80 km2 and is fed by a 730 km2 catchment, which drains an upland plains area through a 15 km wide gap in the crater rim. Valley incision into accumulated debris delivered sediment through a relatively low density valley network to a main stem channel to the fan. An estimated total fan volume of 0.9 km3 matches the calculated volume of removal due to valley incision (0.8 km3) and indicates a mean thickness of 9 m. The fan profile is weakly concave up with a mean slope of 1.5% for the lower portion. Numerous inverted channels outcrop on the western surface of the fan, but on the eastern portion such channels are rare suggesting a change in process from distributary channel domination on the west to sheet flow on the eastern portion of the fan. Runoff (discharge/watershed area) to produce the fan is estimated to be more than 600 m, perhaps as much as 6000 m, indicating a hydrologic cycle that likely lasted at least thousands of years. Atmospheric precipitation (possibly snow) not seepage produced the runoff. Based on topographic data, Peace Vallis fan likely onlapped Bradbury Rise and spilled into a topographic low to the east of the rise. This argues that the light‐toned fractured terrain within this topographic low corresponds to the distal deposits of Peace Vallis fan, and in such a setting, lacustrine deposits are expected.
The impact of climate and reservoirs on longitudinal riverine carbon fluxes from two major watersheds in the Central and Intermontane West
Authors: Stackpoole S. M. , Stets E. G. , Striegl R. G.
Published: March 2014

A nested sampling network on the Colorado (CR) and Missouri Rivers (MR) provided data to assess impacts of large‐scale reservoir systems and climate on carbon export. The Load Estimator (LOADEST) model was used to estimate both dissolved inorganic and organic carbon (DIC and DOC) fluxes for a total of 22 sites along the main stems of the CR and MR. Both the upper CR and MR DIC and DOC fluxes increased longitudinally, but the lower CR fluxes decreased while the lower MRs continued to increase. We examined multiple factors through space and time that help explain these flux patterns. Seasonal variability in precipitation and temperature, along with site‐level concentration versus discharge relationships proved to be significant factors explaining much of the difference among sites located below reservoirs as compared to sites located in more free‐flowing segments of the river. The characterization of variability in carbon exports over space and time provides a basis for understanding carbon cycling and transport within river basins affected by large reservoir systems, particular in arid‐to semi‐arid ecosystems.
A streamline splitting pore‐network approach for computationally inexpensive and accurate simulation of transport in porous media
Authors: Mehmani Yashar , Oostrom Mart , Balhoff Matthew T.
Published: March 2014

Several approaches have been developed in the literature for solving flow and transport at the pore scale. Some authors use a direct modeling approach where the fundamental flow and transport equations are solved on the actual pore‐space geometry. Such direct modeling, while very accurate, comes at a great computational cost. Network models are computationally more efficient because the pore‐space morphology is approximated. Typically, a mixed cell method (MCM) is employed for solving the flow and transport system which assumes pore‐level perfect mixing. This assumption is invalid at moderate to high Peclet regimes. In this work, a novel Eulerian perspective on modeling flow and transport at the pore scale is developed. The new streamline splitting method (SSM) allows for circumventing the pore‐level perfect‐mixing assumption, while maintaining the computational efficiency of pore‐network models. SSM was verified with direct simulations and validated against micromodel experiments; excellent matches were obtained across a wide range of pore‐structure and fluid‐flow parameters. The increase in the computational cost from MCM to SSM is shown to be minimal, while the accuracy of SSM is much higher than that of MCM and comparable to direct modeling approaches. Therefore, SSM can be regarded as an appropriate balance between incorporating detailed physics and controlling computational cost. The truly predictive capability of the model allows for the study of pore‐level interactions of fluid flow and transport in different porous materials. In this paper, we apply SSM and MCM to study the effects of pore‐level mixing on transverse dispersion in 3‐D disordered granular media.
Competing source and loss mechanisms due to wave‐particle interactions in Earth's outer radiation belt during the 30 September to 3 October 2012 geomagnetic storm
Authors: Turner D. L. , Angelopoulos V. , Li W. , Bortnik J. , Ni B. , Ma Q. , Thorne R. M. , Morley S. K. , Henderson M. G. , Reeves G. D. , Usanova M. , Mann I. R. , Claudepierre S. G. , Blake J. B. , Baker D. N. , Huang C.‐L. , Spence H. , Kurth W. , Kletzing C. , Rodriguez J. V.
Published: March 2014

Drastic variations of Earth's outer radiation belt electrons ultimately result from various competing source, loss, and transport processes, to which wave‐particle interactions are critically important. Using 15 spacecraft including NASA's Van Allen Probes, THEMIS, and SAMPEX missions and NOAA's GOES and POES constellations, we investigated the evolution of the outer belt during the strong geomagnetic storm of 30 September to 3 October 2012. This storm's main phase dropout exhibited enhanced losses to the atmosphere at L* < 4, where the phase space density (PSD) of multi‐MeV electrons dropped by over an order of magnitude in <4 h. Based on POES observations of precipitating >1 MeV electrons and energetic protons, SAMPEX >1 MeV electrons, and ground observations of band‐limited Pc1‐2 wave activity, we show that this sudden loss was consistent with pitch angle scattering by electromagnetic ion cyclotron waves in the dusk magnetic local time sector at 3 < L* < 4. At 4 < L* < 5, local acceleration was also active during the main and early recovery phases, when growing peaks in electron PSD were observed by both Van Allen Probes and THEMIS. This acceleration corresponded to the period when IMF Bz was southward, the AE index was >300 nT, and energetic electron injections and whistler‐mode chorus waves were observed throughout the inner magnetosphere for >12 h. After this period, Bz turned northward, and injections, chorus activity, and enhancements in PSD ceased. Overall, the outer belt was depleted by this storm. From the unprecedented level of observations available, we show direct evidence of the competitive nature of different wave‐particle interactions controlling relativistic electron fluxes in the outer radiation belt.
Membranes for Produced Water Treatment
Authors: Hailemariam Leaelaf M. , Johnson Aaron , Roy Abhishek , Olanrewaju Kayode , Reyntjens Kevin
Published: March 2014

Produced water can be defined as water present in a formation with, and brought to the surface with, crude oil or natural gas. More than 87 B barrels of produced water are generated globally each year, constituting the largest wastewater stream generated from petrochemical exploration and production. This amount is expected to grow over the next several years. Increased water demand and tighter regulations are leading to more produced water treatment. Membranes have recently attracted attention for removal of suspended solids, organics and dissolved solids. This article reviews the use of membranes for produced water treatment.
Porous Silicon Resonant Microcavity Biosensor for Matrix Metalloproteinase Detection
Authors: Krismastuti Fransiska S. H. , Pace Stephanie , Voelcker Nicolas H.
Published: March 2014

A real‐time, sensitive, and selective detection device to monitor the healing status of chronic wounds at the point of care is urgently required to render the management of this disease more effective. The photonic properties of porous silicon resonant microcavity (pSiRM) afford an excellent opportunity to be developed as a highly sensitive optical biosensor to monitor the presence of specific biomarkers found in the wound exudate, such as matrix metalloproteinases (MMPs). In this study, the pSiRM is designed, fabricated, and functionalized using a fluorogenic MMP peptide substrate featuring both a fluorophore and a quencher. The peptide‐functionalized pSiRM is then employed as a fluorescence‐based optical biosensor for MMPs. Active MMPs recognize and cleave the peptide sequence of the substrate, producing an immobilized peptide fragment carrying the fluorophore. The fluorescence intensity of the fluorophore embedded within the pSiRM matrix is enhanced by the photonic structure of the pSiRM compared to other pSi photonic structures. This fluorescence enhancement translates into high sensitivity, enabling detection of MMP‐1 at a limit of detection as low as 7.5 × 10−19 m after only 15 min incubation time. Finally, the biosensor also allows the detection and quantification of the concentration of MMPs in human wound fluid.
Lewis Acid‐Mediated Transformations of trans‐2‐Aroyl‐3‐aryl‐ cyclopropane‐1,1‐dicarboxylates into 2‐Pyrones and 1‐Indanones
Authors: Sathishkannan Gopal , Srinivasan Kannupal
Published: March 2014

trans‐2‐Aroyl‐3‐arylcyclopropane‐1,1‐dicarboxylates upon treatment with aluminium(III) chloride (AlCl3) underwent ring‐opening, fragmentation, recombination and lactonization to give highly substituted 2‐pyrones. Alternatively, when treated with titanium(IV) chloride (TiCl4), the cyclopropane diesters underwent a Nazarov cyclization to afford 1‐indanones with high diastereoselectivity.

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Ene‐Carbonyl Reductive Coupling for the Synthesis of 3,3‐Disubstituted Phthalide, 3‐Hydroxyisoindolin‐1‐one and 3‐Hydroxyoxindole Derivatives
Authors: Yeh Chien‐Hung , Lin Yi‐Chuen , Mannathan Subramaniyan , Hung Kevin , Cheng Chien‐Hong
Published: March 2014

An efficient method for the synthesis of three classes of heterocyclic derivatives such as 3,3‐disubstituted phthalides, 3‐hydroxyisoindolin‐1‐ones and 3‐hydroxyoxindoles, is reported. In the presence of the simple reductive system, zinc (Zn)/ammonia (NH3) [or zinc‐copper (Zn‐Cu)/ammonia], a wide range of alkenes including acrylates, acrylonitrile, acrylamide and vinyl sulfoxide underwent reductive coupling with methyl 2‐acylbenzoates and subsequent lactonization to provide 3,3‐disubstituted phthalides in good to high yields at ambient temperature. In a similar manner, 3‐hydroxyisoindolin‐1‐one and 3‐hydroxyoxindole derivatives could also be easily prepared by direct reductive coupling of phthalimides and N‐substituted isatins with activated alkenes, respectively. Application of this methodology towards the synthesis of 1‐naphthol derivatives on a gram scale is also depicted. Furthermore, the intramolecular phthalimides–ene reductive coupling afforded the respective cyclization products with high diastereoselectivity.

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Rotating‐Disk‐Based Direct‐Current Triboelectric Nanogenerator
Authors: Zhang Chi , Zhou Tao , Tang Wei , Han Changbao , Zhang Limin , Wang Zhong Lin
Published: March 2014

An innovative design is reported of a direct‐current triboelectric nanogenerator (DC‐TENG) based on a rotating disk design for harvesting rotational mechanical energy. The DC‐TENG consists of two disks and two pairs of flexible electric brushes that are made of carbon fiber and contact two electrodes, respectively. During the rotation, two disks have distinct triboelectric polarities for a cyclic in‐plane charge separation between them and an alternating current is generated between the two electrodes. Because of the sliding contact and automatically switch between the electric brushes and the two electrodes, the current is reversed in the second half of the cycle and a direct current is generated. The role that the rotating speed and the segmentation number have is thoroughly investigated and shows that there is direct current enhancement not only at higher speed but also with more segments. The DC‐TENG has been demonstrated as a constant current source for directly and continuously driving electronic devices and/or charging an energy storage unit without a rectifier bridge. This work presents a novel DC‐TENG technology and opens up more potential applications for harvesting rotational mechanical energy and powering electronics.