bluuebunny/crossref_metadata_2025 huggingface dataset:
Isoelectric focusing of insulin, 125I-insulin and the 125I-insulin-antibody complex
Authors: Šiševa Asja , Slaninová Jiřina , Barth Tomislav , Ditzov Stephan P. , Sirakov Luben M.
Published: October 2011

Isoelectric focusing on polyacrylamide gel columns of three native crystalline commercial preparations of insulin and 125I-labelled insulin was carried out. All the compounds studied contained three components of different isoelectric points. The largest fraction, having pI 5.60 ± 0.05, was common to all preparations. The other two fractions were situated in the acid region of pH between pI 4.5 and 5.2. The presence of these fractions is explained by the contamination of crystalline insulins by proinsulin and by the formation of des-amido derivatives during the dissolving and storage of insulin samples, and, in case of labelled insulin, also by the presence of heavily iodinated insulin and contaminating components. The isoelectric focusing of the complex 125I-insulin-antibody showed a peak of radioactivity having pI 6.15 ± 0.05.
Purification and properties of phosphoenolpyruvate carboxylase from green leaves of maize
Authors: Mareš Jaroslav , Barthová Jana , Leblová Sylva
Published: October 2011

Phosphoenolpyruvate carboxylate was isolated from green leaves of maize (Zea mays L.) by a procedure including fractionation with ammonium sulphate, chromatography on DEAE-cellulose and preparative electrophoresis on polyacrylamide gel. The specific activity of the electrophoretically homogeneous enzyme was 23 U/mg. Its molecular weight was about 405 000, pH optimum was within the range 7.9 to 8.3, Km for phosphoenolpyruvate was 1.05 . 10-3 and the apparent Km for the magnesium ions was 8.0 . 10-4M. The enzyme was inhibited by malate, aspartate, citrate, pyruvate, ATP and ADP and chloride ions. It was strongly activated by glycine and glucose 6-phosphate and to a lesser degree by glucose 1-phosphate and fructose 1,6-bisphosphate; no activation by orthophosphate and 3-phosphoglycerate was observed.
Porous copolymers of methacrylic acid with N-(2-hydroxypropyl) methacrylamide and (2-hydroxyethyl) methacrylate. Study of sorption properties
Authors: Vacík Jiří , Shataeva Larisa K. , Samsonov Georgii V. , Kálal Jaroslav , Kopeček Jindřich
Published: October 2011

Porous crosslinked copolymers of methacrylic acid with N-(2-hydroxypropyl) methacrylamide (HPMA) or (2-hydroxyethyl) methacrylate were prepared, and the relationship between their structure and the sorption of papain, bovine serumalbumin, chymotrypsinogen, pepsin, ovalbumin, insulin, novocain and oleandomycin were investigated. The presence of hydrophilic components in the gel structure makes possible additional interactions between sorbent and the compound sorbed. The occurrence of additional interactions (probably hydrogen bonds) is more pronounced with cation exchangers containing the (2-hydroxyethyl) methacrylate monomeric unit, which favourably affects the sorption of univalent organic cations but at the same time contributes to the denaturation of sorbed proteins. In contrast to univalent organic cations, cation exchangers containing the N-(2-hydroxypropyl) methacrylamide monomeric unit are more advantageous in the sorption of proteins, because due to the lower extent of additional interactions no irreversible denaturation of sorbed labile proteins takes place in this case.
Phase equilibria in the acetaldehyde-diethyl ether-water system
Authors: Suška Josef
Published: October 2011

Vapour-liquid and liquid-liquid phase equilibria in the ternary acetaldehyde-diethyl ether-water system were determined at isothermal conditions. Experimental vapour-liquid equilibrium data were correlated by the Renon-Prausnitz equation.
Alkaloids from Corydalis cava (L.) SCHW. et KOERTE
Authors: Slavík Jiří , Slavíková Leonora
Published: October 2011

From the tubers of Corydalis cava (L.) SCHW. et KOERTE the following alkaloids were isolated: (+)-bulbocapnine, (+)-corydaline, (+)- and (±)-tetrahydropalmatine, (+)- and (±)-thalictricavine, (+)-corybulbine, corycavine, protopine, (+)-corypalmine, (±)- and (+)-isocorypalmine, (+)-corytuberine, (+)-corydine, (+)- and (±)-corycavidine, (+)-canadine, (+)-stylopine, (-)-scoulerine, capnoidine, dehydrocorydaline, corysamine, coptisine; further the following alkaloids not yet described as components of this plant: (+)-tetrahydrocorysamine, allocryptopine, palmatine, berberine, dehydrocorybulbine, dehydrothalictricavine, (+)-α-stylopine methohydroxide and the alkaloid CC2, as well as the new neutral alkaloids dehydroapocavidine, (+)-bulbocapnine methohydroxide, and α-tetrahydrocorysamine methohydroxide. Further the presence of apocavidine, columbamine, jatrorrhizine and magnoflorine was also proved. In the aerial parts (+)-bulbocapnine, (+)-stylopine, protopine, capnoidine, glaucine, domestine alkaloid CC1 (probably dehydrodomestine), predicentrine, isoboldine corydine, coptisine, corysamine and traces of bulbocapnine methohydroxide were found.
Computation of parameters of a moving uniform fluidized bed of polydisperse granular materials
Authors: Hrdina Miloslav , Neužil Lubomír , Procháska František
Published: October 2011

Relations are presented describing the moving uniform fluidized bed and the computation procedure is proposed. The calculation program given in the language FORTRAN is verified by use of experimental data obtained in measurements with the moving fluidized bed of quartz sand and water.
Determination of dissociation constants of 7-(carboxyphenylazo)-8-hydroxyquinoline-5-sulphonic acids by nonlinear regression of spectrophotometric data
Authors: Meloun Milan , Chýlková Jaromíra
Published: October 2011

Dissociation constants of three metallochromic indicators 7-(o-, m-, p-carboxyphenylazo)-8-hydroxyquinoline-5-sulphonic acids and values of molar absorption coefficients of the forms L3-, HL2-, H2L-, H3L have been determined in 0.1M-NaClO4 medium by non-linear regression of pH-absorbance curves by the program DCLET and by regression matrix analysis of the spectra by the program FA608 + EY608, respectively. All the three derivatives have been synthesized, purified, and their purity checked by chromatography.
Non-Newtonian oscillatory layer flow, approximate solution
Authors: Wein Ondřej
Published: October 2011

The problem of the oscillatory flow of pseudoplastic liquid in vicinity of the infinitely long horizontal plane is formulated in stresses. For Re i.e. for conditions of oscillatory boundary layer the problem is solved approximately by the Galerkin method.
Stop criterion and simulation algorithm
Authors: Ulmanová Marie , Dohnal Mirko
Published: October 2011

Mathematical model of a simulated process describes an actual equipment only with some accuracy. Thus, there is no reason to require that the numerical method should solve the simulation problem with a greater accuracy that with the mathematical model approximates the behaviour of an actual existing equipment. The problem is thus in designing a suitable stop criterion of the simulation problem under uncertainty. The vector standards are used for this purpose. One of the most suitable is the elliptic norm for its simple algorithm and suitable description of the region of uncertainty of solution.
On the analogy between pulsating and vibrating flows
Authors: Wein Ondřej
Published: October 2011

The paper presents theoretical basis for the analogy between the pulsating and vibrating flows enabling a common rheodynamic theory to be formulated for both types of the flow.
The use of chelates of copper, nickel, cobalt, cadmium and zinc with heterocyclic azodyes in the AAS determination of these elements
Authors: Komárek Josef , Havel Josef , Sommer Lumír
Published: October 2011

Of the group of seven pyridyl, thiazolyl and quinolyl azodyes, 2-(2-pyridylazo)-1-naphthol was found to be the most useful for the extraction concentration of traces of copper, nickel, cobalt, cadmium and zinc in methyl isobutyl ketone and for their final determination by atomic absorption spectrophotometry with an acetylene-air flame or using a graphite atomizer. Atomic absorption spectrophotometry was also found to be useful in the study of extraction equilibria and for finding the optimum extraction conditions for these elements with heterocyclic azodyes.
A new chemosensor based on rhodamine 101 hydrazone for Cu (II) in the red region
Authors: Xie Puhui , Guo Fengqi , Li Changshan , Xiao Yue
Published: October 2011

A new chemosensor based on the spirolactam form of rhodamine 101 hydrazone (III) is found to exhibit a reversible colorimetric response toward Cu2+ in aqueous solutions in a selective, sensitive and rapid manner because of a formation of a Cu(II)-III complex. The dominating absorption maximum at 584 nm is uniquely red-shifted among rhodamine chemosensors toward Cu2+. The fluorescence of III can be detected in a low concentration of Cu2+. The results revealed that III is a good colorimetric sensor to Cu2+ in the red region.
CARLESON MEASURE SPACES ASSOCIATED TO PARA-ACCRETIVE FUNCTIONS
Authors: LEE MING-YI , LIN CHIN-CHENG
Published: October 2011

To study the boundedness of the Cauchy integrals over Lipschitz curves, new Hardy spaces [Formula: see text] were introduced in [Y. Han, M.-Y. Lee and C.-C. Lin, Hardy spaces and the Tb theorem, J. Geom. Anal.14 (2004) 291–318], where b is a para-accretive function. In this paper, we define the Carleson measure spaces [Formula: see text] that generalize BMO, and show that [Formula: see text] is the dual space of [Formula: see text]. As an application, we give a Carleson measure characterization of BMOb.
GROUND AND BOUND STATES FOR A STATIC SCHRÖDINGER–POISSON–SLATER PROBLEM
Authors: IANNI ISABELLA , RUIZ DAVID
Published: October 2011

In this paper the following version of the Schrödinger–Poisson–Slater problem is studied: [Formula: see text] where u : ℝ3→ ℝ and μ > 0. The case p < 2 being already studied, we consider here p ≥ 2. For p > 2 we study both the existence of ground and bound states. It turns out that p = 2 is critical in a certain sense, and will be studied separately. Finally, we prove that radial solutions satisfy a point-wise exponential decay at infinity for p > 2.
A UNIFORM QUANTITATIVE FORM OF SEQUENTIAL WEAK COMPACTNESS AND BAILLON'S NONLINEAR ERGODIC THEOREM
Authors: KOHLENBACH ULRICH
Published: October 2011

We apply proof-theoretic techniques of "proof mining" to obtain an effective uniform rate of metastability in the sense of Tao for Baillon's famous nonlinear ergodic theorem in Hilbert space. In fact, we analyze a proof due to Brézis and Browder of Baillon's theorem relative to the use of weak sequential compactness. Using previous results due to the author we show the existence of a bar recursive functional Ω* (using only lowest type bar recursion B0, 1) providing a uniform quantitative version of weak compactness. Primitive recursively in this functional (and hence in T0+ B0, 1) we then construct an explicit bound φ on for the metastable version of Baillon's theorem. From the type level of φ and another result of the author it follows that φ is primitive recursive in the extended sense of Gödel's T. In a subsequent paper also Ω* will be explicitly constructed leading to the refined complexity estimate φ ∈ T4.
Dye sensitized solar cells using non-aggregated silicon phthalocyanines
Authors: Martín-Gomisa Luis , Barea Eva. M. , Fernández-Lázaroa Fernando , Bisquert Juan , Sastre-Santos Ángela
Published: October 2011

Two new silicon phthalocyanines ( SiPcs 1 and 2) axially substituted with carboxylic acid appends have been synthesized and chemically characterized. DSC devices using SiPcs as sensitizers have been prepared for the first time. Although similar HOMO–LUMO values were obtained for both SiPcs , the device prepared with the SiPc 2 gives both higher open circuit voltage (V oc ) and also higher injection (j sc ), so the overall conversion efficiency is larger than for the one where SiPc 1 is used as a dye.
AN INITIALIZATION METHOD FOR FEEDFORWARD ARTIFICIAL NEURAL NETWORKS USING POLYNOMIAL BASES
Authors: VARNAVA THANASIS M. , MEADE ANDREW J.
Published: October 2011

We propose an initialization method for feedforward artificial neural networks (FFANNs) trained to model physical systems. A polynomial solution of the physical system is obtained using a mathematical model and then mapped into the neural network to initialize its weights. The network can next be trained with a dataset to refine its accuracy. We focus attention on an elliptical partial differential equation modeled using a feedforward backpropagation network. We present a numerical example and compare our method with other initialization methods. Our method converges nearly 90% faster compared to random weights, with higher probability of convergence to an acceptable local minimum.
CONSIDERATIONS ABOUT THE NEURAL NETWORK APPROACH FOR ATOMIC AND NUCLEAR SPECTRAL ANALYSIS
Authors: BENNUN L.
Published: October 2011

Although Neural Networks have proliferated for spectroscopic data interpretation, this paper shows, with simple ideas and well-known examples that they are not well suited for this kind of analysis. This conclusion can be understood after we demonstrate that spectroscopic results are absolutely equivalent, from a statistical point of view, to a sequence of statistically independent events. Stochastic independent events, like a dice throw or a coin tossing, cannot be better described than by a purely statistical method. This conclusion remains unchanged independently if the results are linear or not with respect to some parameters of the studied system, as is depicted in this work. If a method performs better than statistical methods for spectral analysis, it could be understood that it is violating the causality principle. As a representative example, it is described the particle transport equation (Boltzmann's Equation) solved by Monte Carlo methods, with which we can simulate a general spectroscopic technique. Also are described the Total Reflection X-ray Fluorescence and the Neutron Activation Analysis Techniques. In none of these systems it would be expected that Neural Networks perform better than statistical methods for spectral analysis.
DESIGN AND FABRICATION OF A 20 MHz ANNULAR ARRAY FOR MEDICAL ULTRASOUND
Authors: HU ZHENHUA , PENG JUE
Published: October 2011

Most high frequency (> 15 MHz) medical ultrasound systems are based on single element transducers mechanically scanned. These systems can provide images with excellent resolution. However, single element transducers are often limited by the fixed focal point and small depth of field. Annular arrays consisting of concentric rings of elements are focused electronically. These arrays are desirable to avoid the fixed focal point of the single element transducers and improve the depth of field. This paper reports the design, fabrication, and characterization of a 5-element equal-area annular array transducer. After electrical impedance matching, the average center frequency was 20 MHz and -6 dB bandwidths ranged from 34 to 42%. The ILs for the matched annuli ranged from 6.1 to 26.5 dB.
Present Status and Future Prospects of Quantum Information Processing: With Special Focus on Optically Controlled Semiconductor Spins and Single-Photon Technologies
Authors: Yamamoto Yoshihisa
Published: October 2011

The scheme of directly controlling electron spins trapped in semiconductor quantum dots or donor impurities as qubits using optical pulses has various advantages, such as the achievements of local excitation and fast operation, low power consumption, easy implementation of an interface with optical fiber communication networks, and the capability of transferring information to nuclear spins, which are expected to serve as quantum memories with a long coherence time. In this report, I introduce the present status of the research and development of this scheme and discuss its potential application to quantum information processing.
Temperature Dependent Capacitance–Voltage Analysis of Unintentionally Doped and Si Doped Al0.82In0.18N Grown on GaN
Authors: Chung Roy B. , Bierwagen Oliver , Wu Feng , Keller Stacia , DenBaars Steven P. , Speck James S. , Nakamura Shuji
Published: October 2011

Unintentionally doped (UID) and Si doped Al0.82In0.18N samples were grown on Si-doped GaN by metalorganic chemical vapor deposition. The high structural quality of the Al0.82In0.18N layers was confirmed by high resolution X-ray diffraction and transmission electron microscopy. Secondary ion mass spectrometry measurement showed oxygen levels of (2–6)×1018 cm-3 regardless of the explored growth conditions. Vertical Schottky diodes were fabricated with a Pd-based Schottky contact on Al0.82In0.18N and Ti/Al/Ni/Au-based ohmic contact on n-type GaN. Capacitance–voltage (C–V) analysis showed that UID Al0.82In0.18N was an n-type with a carrier density of about 3×1017 cm-3 in the bulk region at 300 K. Based on the temperature dependent C–V analysis from 100 to 300 K, the donor activation energy was found to be 4 meV, showing very weak temperature dependence despite the large bandgap of Al0.82In0.18N. Si-doped Al0.82In0.18N ([Si] ≃2×1018 cm-3) showed almost no carrier freeze-out at carrier density of 1.0×1018 cm-3.
Use of Sub-nanometer Thick AlN to Arrest Diffusion of Ion-Implanted Mg into Regrown AlGaN/GaN Layers
Authors: Chowdhury Srabanti , Swenson Brian L. , Lu Jing , Mishra Umesh K.
Published: October 2011

Diffusion of Mg from Mg-ion-implanted GaN layer to metalorganic chemical vapor deposition (MOCVD) regrown AlGaN/GaN layers was detected and identified as a critical problem in devices which are dependent on layers implanted with Mg for its current blocking properties. Surface treatments done to etch away the Mg rich layer prior to the regrowth was not beneficial unlike in the case of the GaN doped with Mg. Remarkably, regrowth of a sub-nanometer thick (7 Å) AlN layer on top of the Mg-implanted GaN was found to be effective in arresting the Mg from diffusing out into the AlGaN/GaN layers grown on top at 1160 °C. This was verified from both secondary ion mass spectrometry (SIMS) analysis and electrical (capacitance–voltage) data. This result is significant because at such thickness the AlN would not impact the crystal quality of the overgrown material and serve as a viable method of achieving a current blocking structure by MOCVD growth technique.
Estimation of Piezoelectric Response Using Maximally Localized Wannier Function and Its Application to the Bismuth-Based Ferroelectric Materials
Authors: Okuno Yukihiro , Sakashita Yukio
Published: October 2011

Estimation of piezoelectric coefficient using maximally localized Wannier function (MLWF) is performed for several ferroelectric materials. The advantage of this method is that we can decompose the piezoelectric coefficient into each orbital of MLWF and can obtain physical information on the piezoelectric response from the viewpoint of electric structure. We divide the piezoelectric coefficient into the “electric” and “ionic” parts. For the electric part, we further divide it into each MLWF orbital contribution. We have applied this method to BaTiO3, PbTiO3, and the bismuth-based ferroelectric materials BiAlO3 and BiFeO3. We show the detailed characteristics of the piezoelectric response in these materials.
Molecular-Chain Formation Induced by Infrared-Laser Light Observed in L-Cysteine and Potassium Dihydrogenphosphate
Authors: Tsujibayashi Toru , Ichimiya Masayoshi , Toyoda Koichi , Ohno Nobuhito
Published: October 2011

Each of amino acids and phosphate group is capable of forming a chain through repeating dehydration condensation reaction. We have observed Raman scattering spectra of L-cysteine (HSCH2CH(NH2)COOH) and potassium dihydrogenphosphate (KH2PO4 or KDP) before and after irradiation of one pulse of an erbium-doped yttrium aluminum garnet (Er:YAG) laser with its wavelength of 2.94 µm, duration of 0.2 ms, and peak power density of 0.4 MW/cm2. Extra peaks are observed in the spectra after the irradiation, which are not seen in the spectra before the laser irradiation. Comparison of the experimentally obtained spectra with the calculated ones of the chain compounds suggests that the laser light does induce such reactions.
In-situ Determination of Interface Dipole Energy between Tris(8-hydroxyquinoline) Aluminum and MgO Coated Al in Inverted Top-Emitting Organic Light-Emitting Diodes
Authors: Kim Soo Young , Hong Kihyon , Lee Jong-Lam
Published: October 2011

The interface dipole energies between tris(8-hydroxyquinoline) aluminum (Alq3) and Al/MgO (or bare Al) were in-situ measured using synchrotron radiation photoemission spectroscopy. The work function of Al/MgO is higher by 0.6 eV than that of Al. The interface dipole energies were determined to be -0.3 and 0.2 eV for Al/MgO and bare Al, respectively. Therefore, the barrier height of Al/MgO is higher by 0.3 eV than that of Al. The operating voltage at a current density of 50 mA/cm2 of inverted top-emitting organic light-emitting diode (ITOLED) using Al/MgO cathode decreased from 14.3 to 11.7 V, and the luminance value at the current density of 222 mA/cm2 of ITOLED increased from 1830 to 1950 cd/m2. Therefore, it is considered that MgO interfacial layer played a role in reducing the effective barrier height of electron injection by tunneling mechanism, leading to a reduction in turn-on voltage and luminance enhancement.
Thermal Expansion of Alkaline-Earth-Metal Disilicides AeSi2 (Ae= Ca, Sr, and Ba)
Authors: Imai Motoharu
Published: October 2011

The thermal expansion of alkaline-earth-metal disilicides AeSi2 (Ae= Ca, Sr, and Ba) has been investigated at temperatures ranging from room temperature to 873 K using powder X-ray diffractometry. The coefficients of linear thermal expansion, α
i
's, of AeSi2 range from 9 ×10-6 to 18 ×10-6 K-1, which are larger than those of Si (2.6 ×10-6 K-1 at 298 K) and group 4–7 transition-metal disilicides [(6–11) ×10-6 K-1 at 298 K]. The coefficients of volume thermal expansion, α
V
, range from 3.2 ×10-5 to 4.8 ×10-5 K-1 in AeSi2. The α
V
becomes larger in the order of CaSi2, SrSi2, and BaSi2. This order of magnitude of α
V
is related to the order of magnitude of bulk modulus B
0 using Grüneisen's rule. The residual stresses in AeSi2 film are discussed using the obtained α
i
.
Broadband Second-Harmonic Generation in the Near-Infrared Region in a Tapered Zinc Selenide Slab Using Total Internal Reflection Quasi-Phase Matching
Authors: Saha Ardhendu , Deb Sumita
Published: October 2011

We analytically describe the concept of broadband second-harmonic generation in the near-IR region in an isotropic tapered semiconductor slab made of zinc selenide. A computer-aided simulation has been carried out to determine the possibility of generating broadband second-harmonic intensity when broadband fundamental laser radiation is allowed to undergo total internal reflection inside the tapered semiconductor slab. The simulated results indicate an extremely broad spectral bandwidth of 557 nm centered at 4.05 µm (3.812 to 4.369 µm) in a 10-mm-long slab with a conversion efficiency of 0.02%. The losses due to absorption and surface roughness of the semiconductor material have been considered in the analysis. The effects of variations in the temperature, length, and tapering angle of the semiconductor slab have been studied for the generated second-harmonic radiation.
Spectral and Polarization Characteristics of Photonic Crystal under Normally Incident Light and Their Tuning with Liquid Crystal Control
Authors: Inoue Naoko , Baba Toshihiko
Published: October 2011

The transmission and polarization characteristics of a photonic crystal (PC) in a surface-normal application are examined, and the use of a liquid crystal (LC) as a tunable anisotropic element is investigated. PC slabs fabricated from Si3N4 by etching a square-lattice pattern of circular or elliptical holes are demonstrated to exhibit guided resonance due to coupling of light with in-plane Bloch modes. Structural birefringence arising from the ellipticity of holes is also observed. The results are in good agreement with photonic band analysis. With LC filling the holes, the resonance and polarization characteristics of the PC device are shown to be dependent on the isotropic or nematic state of the LC, which can be switched by temperature. These behaviors are explained by finite-difference time-domain simulations assuming anisotropic orientation of nematic LC molecules in the pattern holes. The present study thus demonstrates the possibility of surface-normal-type light control devices.
On the Focused Field Embedded in a Super Rens Medium
Authors: Assafrao Alberto C. , Pereira Silvania F. , Urbach H. Paul
Published: October 2011

A rigorous electromagnetic computational model is presented to simulate the near field characteristics of the focused spot in an embedded super rens medium. The super resolution effect is described using a threshold model, where the material refractive index is changed instantaneously under laser exposure above a certain threshold. The simulations reveal interesting features of the Super Rens focused spot and demonstrate how super resolution is achieved. This model is useful for a better understanding of the super resolution effect in optical data storage and other super resolution applications.
Photoluminescent Characteristics of Mn2+ Centers Selectively Substituted for Different Cations in CuAlS2
Authors: Miyamoto Yoshinobu , Honma Tetsuo , Ohmi Koutoku
Published: October 2011

A selective substitution of Mn2+ centers for different cations has been attempted in CuAlS2 powder samples. From the theoretical curve fittings of the extended X-ray absorption fine structure oscillations, it has been confirmed that most Mn is incorporated as divalent into one site of Cu or Al, as intended. The Mn2+ centers substituted for Cu show an orange photoluminescence with a peak wavelength of 600 nm. This orange emission has a single exponential decay curve with a decay constant of 1.0 ms. By contrast, the Mn2+ centers substituted for Al show a red emission peaking at 640 nm and have a nonexponential decay curve with a decay constant of 100 µs. This fast emission is thought to be due to the intrinsic luminescence of the 3d5–3d5 transition in Mn2+ centers occupying the Al site. The currently obtained external quantum efficiency is about 40% under 360 nm excitation at room temperature.
Electrochromic Property of MoO3 Thin Films Deposited by Chemical Vapor Transport Synthesis
Authors: Kim Dae-Gun , Kim Se Hoon , Kim Young Do
Published: October 2011

The transmittance of electrochromic MoO3 thin films by chemical vapor transport (CVT) deposition and post-annealing on indium tin oxide (ITO) glass reached 80% with low reflectivity. Optical analysis demonstrated a 3.60 eV band gap energy in MoO3 thin film. Transmittance changes of 50% between coloration and decoloration (∼30 and ∼80%) at 533 nm under the bias change frequency revealed reversible electrochromic properties and stability. A coloration efficiency of the annealed MoO3 thin film was 23.7 cm2/C. Coloration responsibility was predominant with reliable performances by bias change.
Real-Time Time–Frequency Imaging of Ultrashort Laser Pulses Using an Echelon Mirror
Authors: Katayama Ikufumi , Sakaibara Hiroyuki , Takeda Jun
Published: October 2011

We demonstrate real-time time–frequency imaging for the autocorrelation traces of ultrashort laser pulses using an echelon mirror fabricated on a Ni block with 500 steps; the echelon mirror is employed to generate spatially encoded time delays for the probe pulses. By using the frequency-resolved optical gating (FROG) technique with the echelon mirror, the time–frequency images of ultrashort laser pulses were successfully mapped in real-time. The chirp characteristics of the laser pulses were also evaluated with the phase-retrieval procedure on a single-shot basis. Our technique provides significant advantages over conventional autocorrelation and FROG techniques, such as single-shot detection of time–frequency images, a small spot size at a nonlinear crystal, chirp-free characteristics of echelon mirrors, and ultrafast measurement capabilities by simply replacing the nonlinear crystal with samples. Hence, we believe that it becomes a powerful spectroscopic tool for monitoring ultrashort laser pulses and for investigating ultrafast dynamics of materials.
Generation of Spin Current in Bipolar Conductors
Authors: Sakai Masamichi , Sakuraba Takahito , Honda Zentaro , Hasegawa Shigehiko , Kitajima Akira , Higuchi Koji , Oshima Akihiro , Nakamura Osamu
Published: October 2011

The ordinary Hall effect (OHE), which is caused by an external magnetic field, was studied as a mechanism for the generation of spin current. It has been theoretically elucidated that, under an open-circuit condition, the OHE can contribute to spin-current generation when spin-polarized electrons and holes are simultaneously present as mobile carriers. This OHE contribution to spin current generation is caused by the steady-state kinematics of electrons and holes whose transverse velocities have the same direction. Although anomalous Hall effects may contribute to spin-current generation, the OHE plays a principal role in the generation of spin current when electrons and holes have approximately the same transport characteristics. The experimental aspects of possible materials for the isomorphic electron and hole systems are argued on the basis of the experimental results of the magnetotransport measurement of yttrium dihydride and preliminary results of the magnetization measurement of hydrogenated films of gadolinium.
Growth of Narrow and Straight Germanium Nanowires by Vapor–Liquid–Solid Chemical Vapor Deposition
Authors: Simanullang Marolop , Usami Koichi , Kodera Tetsuo , Uchida Ken , Oda Shunri
Published: October 2011

This paper describes the growth of germanium nanowires (Ge NWs) via vapor–liquid–solid (VLS) mechanism by the low-pressure chemical vapor deposition (CVD) technique. A systematic study of the growth conditions of the Ge NWs has been conducted by varying the size of the Au nanoparticles and the substrate temperature. The tapering of the nanowires has been minimised when the growth temperature is lowered from 300 to 280 °C which also contributes to the decrease in the diameter of the Ge NWs. The growth temperature of 280 °C yields Ge NWs with diameters of less than 5 nm, offering an opportunity for the fabrication of high-performance germanium nanowire field-effect transistors.
Bipolar Thermoelectric Effect in a Serially Coupled Quantum Dot System
Authors: Kuo David M.-T. , Chang Yia-chung
Published: October 2011

The Seebeck coefficient (S) of a serially coupled quantum dot (SCQD) junction system is theoretically studied via a two-level Anderson model. A change of sign in S with respect to temperature is found, which arises from the competition between tunneling currents due to electrons and holes (i.e., bipolar tunneling effect). The change of sign in S implies that one can vary the equilibrium temperature to produce thermoelectric current in either the forward or reverse direction, leading to a bipolar thermoelectric effect. For the case of two parallel SCQDs, we also observe the oscillatory behavior of S with respect to temperature.
Possibility of Freely Achievable Multilevel Storage of Phase-Change Memory by Staircase-Shaped Pulse Programming
Authors: Yin You , Noguchi Tomoyuki , Hosaka Sumio
Published: October 2011

We investigate the effect of the staircase-shaped pulse with two subpulses on programming characteristics in the double-layered phase-change memory for freely achievable multilevel storage. Phase-change material is melted during the first subpulse and the second one is used for controlling the total crystallinity after melting because it generally acts as crystallization time. Our finite-element analysis shows that the shorter the second subpulse is, the lower the crystallinity is. It is experimentally demonstrated that the device resistance increases with decreasing the width of the second subpulse owing to the decreasing crystallinity. This implies that any resistance levels are expected to be freely achieved by staircase-shaped pulse programming.
Influence of V/III Ratio of Low Temperature Grown AlN Interlayer on the Growth of GaN on Si<111> Substrate
Authors: Luo Ruihong , Xiang Peng , Liu Minggang , Chen Tufu , He Zhiyuan , Fan Bingfeng , Zhao Yu , Xian Yulun , Huang Shanjin , Zheng Zhiyuan , Wu Zhisheng , Jiang Hao , Wang Gang , Liu Yang , Zhang Baijun
Published: October 2011

In this work, the influence of the V/III ratios of the low temperature (LT) AlN interlayer on GaN grown on Si<111> substrate have been investigated. It was found that V/III ratio of LT-AlN interlayer is another important growth parameter, which the crystalline quality of GaN was strongly dependent on. By optimizing the V/III ratio of LT-AlN, the high quality crack-free GaN epilayer with lower dislocation density on Si substrate have been obtained. We attribute it to the different LT-AlN surface morphology originated from optimizing the V/III ratio. Different V/III ratios could result in different GaN growth rates in vertical and lateral direction, which could effectively prevent the threading dislocation from penetrating through the LT-AlN interlayer.
Electrical Characteristics of Pt Schottky Contacts Fabricated on Amorphous Gallium Indium Zinc Oxides
Authors: Kim Hyunsoo , Kim Seongjun , Kim Kyoung-Kook , Lee Sung-Nam , Ahn Kwang-Soon
Published: October 2011

The electrical characteristics of Pt Schottky diodes fabricated on amorphous gallium indium zinc oxide were investigated. On the basis of Schottky theory with the thermionic emission mode, an effective Schottky barrier height (SBH) of 0.55 eV and an ideality factor of 3.38 were obtained. The anomalously high ideality factor could be attributed to the statistical potential variations of conduction band edges, as evidenced from the distinctive carrier transport through percolation hopping conduction. In this respect, the barrier inhomogeneity model was applied to obtain reasonable Schottky parameters, yielding the mean barrier height of 1.23 eV with a large standard deviation of 192 mV.
Degradation Analysis of Electrochromic Switchable Mirror Glass Based on Mg–Ni Thin Film at Constant Temperature and Relative Humidity
Authors: Tajima Kazuki , Hotta Hiromi , Yamada Yasusei , Okada Masahisa , Yoshimura Kazuki
Published: October 2011

An electrochromic mirror glass that can be switched between reflective and transparent states by voltage application is presented. For the practical applications of such a device such as in energy-saving windows, optical devices, and electronic devices, the effects of environmental factors such as temperature and humidity on the optical switching properties of the device should be investigated in detail. In this work, the effects of constant temperature and relative humidity conditions on the device properties were studied. In particular, surface analysis studies were conducted. When these devices were kept at 40 °C and 60% relative humidity (RH), the speed of switching from the reflective state to the transparent state decreased with increasing time of storage in the bath. This reduced switching speed was related to the degradation of the surface metallic layers of the device, which could be observed by transmission electron microscopy (TEM) as an increase in surface roughness (R
a = 19.8 nm). Although the as-prepared device had a Mg4Ni optical switching layer approximately 40 nm in typical thickness, the degraded device exhibited an expanded layer of approximately 78 nm thickness. This increased thickness was associated with the change to the nonmetallic states of oxide and hydroxide from the metallic states of magnesium and nickel in the layer because of the adverse effects of the atmosphere.
Theoretical Calculations for Magnetic Property of FeRh Inter-Metallic Compound with Site-Exchange Defects
Authors: Kaneta Yasunori , Ishino Shiori , Chen Ying , Iwata Shuichi , Iwase Akihiro
Published: October 2011

To clarify the relationship between a magnetic property and a defect structure in FeRh inter-metallic compound theoretically, energy band calculations are performed based on the density functional theory. Under the assumption that the majority of defect structure is a type of site-exchanged one between Fe and Rh atoms, total energy for various magnetic structures is evaluated within a super-cell of 2×2×2 cubic cells. Due to the site-exchange defect pair of nearest neighbor Fe and Rh atoms in 12.5%/f.u. (f.u.: formula unit) density, the total energy increases by 1.91 eV/pair in the anti-ferromagnetic structure and 0.88 eV/pair in the ferromagnetic structure. Although the anti-ferromagnetic structure is the stable state at low temperatures in defect-free FeRh, it becomes unstable with an amount of the site-exchange defect density. Threshold defect density to stabilize ferromagnetic state is estimated to be 0.8%/f.u. This phenomenon is expected in ion irradiated FeRh.
Development of Neutral Beam Source Using Electron Beam Excited Plasma
Authors: Hara Yasuhiro , Hamagaki Manabu , Mise Takaya , Hara Tamio
Published: October 2011

A low-energy neutral beam (NB) source, which consists of an electron-beam-excited plasma (EBEP) source and two carbon electrodes, has been developed for damageless etching of ultra-large-scale integrated (ULSI) devices. It has been confirmed that the Ar ion beam energy was controlled by the acceleration voltage and the beam profile had good uniformity over the diameter of 80 mm. Dry etching of a Si wafer at the floating potential has been carried out by Ar NB. Si sputtering yield by an Ar NB clearly depends on the acceleration voltage. This result shows that the NB has been generated through the charge exchange reaction from the ion beam in the process chamber.
Secondary Ionization Coefficient of MgO and Accumulated Charge
Authors: Suzuki Susumu , Sekizawa Takashi , Kashiwagi Yasuhide , Itoh Haruo
Published: October 2011

An experimental study on Townsend's secondary ionization coefficient γ of MgO is carried out in accordance with a previously reported sequential procedure. A sinusoidal voltage is applied between the MgO film electrode and a stainless-steel electrode in the frequency range of 0.1 Hz–2 kHz. The breakdown voltage is determined from the observed waveforms of applied voltage and accumulated charge on the MgO film electrode. The influence on the breakdown voltage of the voltage induced by the accumulated charge is investigated. We found that the accumulated charge does not affect the breakdown voltage at low frequency or the DC voltage, but it affects the breakdown voltage at high frequency. Using the breakdown voltage, we determine Townsend's secondary ionization coefficient γ of MgO. The obtained γ for MgO in the study is compared with other reported values. It is found that γ for MgO is larger than those of metallic electrodes.
Theoretical Study of Exposure Latitude of Chemically Amplified Resists Used for Extreme Ultraviolet Lithography
Authors: Kozawa Takahiro , Tagawa Seiichi
Published: October 2011

The trade-off relationships between resolution, line edge roughness (LER), and sensitivity are well known and the most serious problem in the development of chemically amplified resists used for extreme ultraviolet (EUV) lithography. Also, the exposure latitude (EL) is an important factor from the viewpoint of the productivity of production lines of semiconductor devices. However, the relationships of EL with resolution, LER, and sensitivity remain unclear. In this study, the EL of chemically amplified EUV resists was investigated using simulation based on reaction mechanisms. The relationship between EL and LER depended on dissolution point and quencher concentration. EL and resolution had a trade-off relationship. The relationship between EL and sensitivity was also a trade-off one with a weak dependence under the simulation conditions used in this study.
Fabrication of Einzel Lens Array with One-Mask Reactive Ion Etching Process for Electron Micro-Optics
Authors: Miyashita Hidetoshi , Tomono Eiichi , Kawai Yusuke , Toda Masaya , Esashi Masayoshi , Ono Takahito
Published: October 2011

In this paper, we report the fabrication of electron micro-optics by using deep reactive ion etching of three stacked silicon wafers. The three 120-µm-thick silicon wafers stacked with cavities are etched by a direct cavity through etching technique, where each wafer is bonded with a 200-µm-thick glass with through holes, thus separated by a space in part. An array of the electron micro-optics consisting of three electrodes can be fabricated by a one-mask process without assembling and alignment process. The dimensional profiles of a sample etched using this technique are also investigated. This micro-optics fabrication technology is useful for making future multiple electron beam devices with electron optics.
Control of Droplet Generation in Flow-Focusing Microfluidic Device with a Converging-Diverging Nozzle-Shaped Section
Authors: Chen Jerry M. , Kuo Ming-Che , Liu Chien-Po
Published: October 2011

In this study, we present experiments on the generation and control of droplets with a wide range of size in a microfluidic device composed of flow-focusing (cross-junction) geometry with a converging-diverging nozzle-shaped section. The microfluidic structure was made of poly(dimethylsiloxane) (PDMS) for the generation of water-in-oil droplets. It is found that adding the converging-diverging section to the cross-junction significantly reduces the droplet size without greatly increasing the overall flow resistance and still achieves good uniformity. The throat of the converging-diverging section determines the breakup location of the droplet emulsion. The effects of the throat width on the scaling for the size of droplets are most pronounced in the higher range of the continuous-phase to dispersed-phase flow rate ratio, where the shear-driven mechanism dominates the breakup. In this regime, the shearing effects are largely enhanced by the strong acceleration and deceleration created in the converging-diverging section. These effects enable us to generate droplets with a wide range of diameter, including those as small as 10 µm or less, in the microfluidic devices having channel dimensions on the order of 100 µm.
Growth of Spin-Coated ZnO Films Using Diethylzinc Solution
Authors: Yoshino Kenji , Shinmiya Masato , Kamiya Naomi , Kosaka Junko , Oshima Minoru , Takemoto Yujin , Toyota Kouji , Inaba Koichiro , Haga Ken-ichi , Tokudome Koichi
Published: October 2011

Nondoped ZnO films on a glass substrate have been successfully grown by conventional spin coating at room temperature using a diethylzinc-based solution. The samples have an optical transmittance of more than 80%, and a smooth surface determined from optical transmittance and scanning electron microscopy, respectively.
Dependence of Resonant Voltage on Quantum-Well Width in CaF2/Fe3Si/CaF2 Resonant Tunneling Diodes
Authors: Sadakuni-Makabe Kenji , Suzuno Mitsushi , Harada Kazunori , Akinaga Hiro , Suemasu Takashi
Published: October 2011

200-nm-diameter CaF2 (5 nm)/Fe3Si/CaF2 (5 nm) ferromagnetic resonant tunneling diodes (FM-RTDs) were fabricated on a Si(111) substrate through SiO2 hole arrays by selective-area molecular beam epitaxy. Fe3Si quantum-well width (d) values of 4, 5, and 8 nm were used. The current density versus voltage (J–V) characteristics were measured at room temperature and the peak-voltage separations in d
2
J/d
V
2–V plots were found to be inversely proportional to d
2. This result implies that resonant tunneling occurs in the FM-RTDs.
Impact of Thermally Induced Structural Changes on the Electrical Properties of TiN/HfLaSiO Gate Stacks
Authors: Yamamoto Takashi , Ogawa Shingo , Arimura Hiroaki , Saeki Masayuki , Kitano Naomu , Hosoi Takuji , Shimura Takayoshi , Watanabe Heiji
Published: October 2011

Thermally induced structural changes in TiN/Hf(La)SiO gate stacks were investigated by back-side X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS). A distinct correlation between bottom oxide growth and an increase in equivalent oxide thickness (EOT) was confirmed under high-temperature annealing at over 850 °C regardless of La content. Back-side XPS also revealed that oxygen and nitrogen diffusion occurs, forming partially oxidized TiON layers at a metal/high-k interface under moderate annealing temperatures of approximately 600 °C, and that annealing at over 750 °C leads to the reduction of the oxide phase and produces a thinner inter-layer with a clear Ti–N bond feature. Moreover, with an increase in annealing temperature, a change in the local atomic configuration in the HfLaSiO dielectric layer was identified from oxygen K-edge spectra. This structural change induced by thermal reaction can be considered as a possible cause of the V
th instability of La-incorporated high-k gate stacks. On the basis of these findings on structural changes, the physical origins of the effective work function modulation of the gate stacks are discussed in detail.
Effect of Y Content in (TaC)1-xYx Gate Electrodes on Flatband Voltage Control for Hf-Based High-k Gate Stacks
Authors: Homhuan Pattira , Nabatame Toshihide , Chikyow Toyohiro , Tungasmita Sukkaneste
Published: October 2011

The effects of varying the yttrium (Y) level in a (TaC)1-x
Y
x
gate electrode on the structural and electrical properties of a hafnium (Hf)-based high-k metal–oxide–semiconductor (MOS) capacitor, including flatband voltage (V
fb), were evaluated. The composition of (TaC)1-x
Y
x
was controlled by the power of pure TaC and Y targets in magnetron sputtering. The structure of the formed (TaC)1-x
Y
x
film was that of either a face-center cubic (fcc) at all compositions of x≤0.4 or amorphous at x≥0.5 after annealing at temperatures below 600 °C. X-ray photoelectron spectroscopy (XPS) analysis revealed that the TaC and (TaC)1-x
Y
x
films all contained about 10% oxygen. The resistivity of the (TaC)1-x
Y
x
films was invariant for all compositions of x≤0.5, but it increased with increasing annealing temperature up to 600 °C for compositions of x≥0.68. In the as-deposited case, the effective work function, which was estimated from the relationship between V
fb and the equivalent oxide thickness of the HfO2 film, clearly changed from 4.8 to 4.3 eV as x increased. The V
fb of HfO2 and HfSiO
x
dielectrics could be controlled within 0.5 V after annealing at 500 °C by changing the composition of the (TaC)1-x
Y
x
film (in terms of x). Based on the experimental data, it is clear that (TaC)1-x
Y
x
composites are candidate materials for n-metal gate electrodes in the gate-last process.
Preparation and Electrical Characterization of CeO2Films for Gate Dielectrics Application: Comparative Study of Chemical Vapor Deposition and Atomic Layer Deposition Processes
Authors: Kouda Miyuki , Ozawa Kenji , Kakushima Kuniyuki , Ahmet Parhat , Iwai Hiroshi , Urabe Yuji , Yasuda Tetsuji
Published: October 2011

We report on the preparation of CeO2films by two different processes: chemical vapor deposition (CVD) by the thermal decomposition of Ce(Mp)4and atomic layer deposition (ALD) by the hydrolysis of Ce(EtCp)3and Ce(iPrCp)3. CVD at 350 °C produced polycrystalline cubic CeO2films with good thickness uniformity. For both CVD and ALD processes, the metal–oxide–semiconductor (MOS) capacitors subjected to 500 °C annealing showed capacitance–voltage (C–V) characteristics with small hystereses (<1 mV) and flatband voltage shifts (<0.1 V). The frequency dispersion of theC–Vcurves, which is ascribed to the dielectric relaxation of CeO2, correlated with the crystallinities of the CVD and ALD films.