bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous measurement of film thickness and wall shear stress in wavy flow of non-Newtonian liquids
Authors: Sobolík Václav , Wein Ondřej , Čermák Jan
Published: June 2010

The film thickness and wall shear stress were measured simultaneously by electrodiffusional and capacitance methods. Experimental data were confronted with the existing theories of gravity flow of non-Newtonian liquids in wavy films with free surface.
Salt purification by recrystallization. Application of the homogeneous distribution law
Authors: Mayrhofer Benitto , Nývlt Jaroslav
Published: June 2010

In a recently published series of papers on mathematical modelling of salt purification by recrystallization, the microcomponent distribution was assumed to follow the homogeneous distribution law Y = kHX, where X and Y are the mean masses of the microcomponent per unit mass of the macrocomponent in the liquid and solid phases, respectively, and kH is the analytically determined distribution coefficient of the microcomponent. From the physical point of view, it is more rigorous to assume the validity of an equation of the form Y = kH*X, where Y and X are the masses of the microcomponent per unit mass of the macrocomponent at the surface of the solid phase and in the solution, respectively, and kH* is the homogeneous distribution coefficient relating to the equilibrium between the microcomponent and macrocomponent in the solution and at the crystal surface (whereas the analytically determined kH relates to the equilibrium with respect to the bulk of the crystals). This paper presents a simple relationship between the empirical coefficients of the two equations, permitting the recrystallization process to be described by means of the original simple equation using analytically determined component concentrations.
Cementation kinetics of copper on a rotating zinc cylinder
Authors: Glaser Vladimír , Vídenský Jan , Kužela Miroslav
Published: June 2010

The authors followed the course of cementation of copper from sulphate solutions on a rotating zinc cylinder. Treatment of experimental data revealed that the coefficient of proportionality in the kinetic equation is not influenced by the Cu layer deposited on the zinc surface and is independent of the concentration of Cu(II) ions, but decreases with increasing concentration of ZnSO4 in solution. The cementation reaction proceeds in the diffusion region and is of the first order with respect to the concentration of Cu(II) ions; the proportionality constant in the rate equation corresponds to the mass transfer coefficient.
Catalytic activity of cobalt(II) tetrasulphophthalocyanine for the oxidation of sulphite ions and other substrates by dioxygen
Authors: Wagnerová Dana M.
Published: June 2010

The oxidation of sulphite ions by dioxygen in the presence of cobalt(II) tetrasulphophthalocyanine (CoTSP) is catalyzed by traces of metal ions in the system and not by the complex itself. The addition of EDTA completely suppresses the oxidation of sulphite ions even in the presence of CoTSP. When the oxidation of a substrate is actually catalyzed by CoTSP, EDTA has no effect on the reaction rate. The catalytic effect of CoTSP is observed if the substrate and the catalyst form a reactive binary adduct, CoTSP substrate, responsible for an absorption band near 450 nm.
Synthesis of 5α-cinobufagin
Authors: Kamano Yoshiaki , Drašar Pavel , Pettit George R. , Tozawa Machiko
Published: June 2010

Cinobufagin (I) and cinobufotalin (IV) isolated from the Chinese toad venom preparation Ch'an Su were used as starting points for synthesis of 5α-cinobufagin (III) via the 3-oxo-4-ene derivative VII. Lithium borohydride reduction of ketone VII afforded 5α-cinobufagin (III) accompanied by 3-epicinobufagin (IX). Ring A diene II, was obtained as one of the dichlorodicyanobenzoquinone oxidation products of 3-oxocinobufagin (V).
Analysis of the oscillatory behaviour of an industrial reactor for the oxonation of propene. Evaluation of flow models based on the response to a pulse signal
Authors: Horák Josef , Bělohlav Zdeněk , Madron František
Published: June 2010

The response of an industrial reactor for the oxonation of propene to its spiking with a radioactive tracer was compared with simulated responses obtained for models of various structures, viz. a cascade of two perfectly stirred cells of different size, a cascade of two perfectly stirred cells of the same size with recirculation of the reaction mixture, a cascade of two perfectly stirred cells of the same size with inflow into both cells, and a system of two perfectly stirred cells with back-flow involving a plug-flow element. None of the flow models fitted the experiment perfectly; the best fit was obtained for the combination of perfectly stirred cells and back-flow with a plug-flow element.
Quantum-chemical analysis of small silver clusters
Authors: Gadiyak Grigorii V. , Morokov Yurii N. , Tomášek Mojmír
Published: June 2010

Total energy calculations of three- and four-atomic silver clusters have been performed by the spin-polarized version of the CNDO/2 method to get the most stable equilibrium geometries, atomization energies, and charge and spin distribution on the atoms for three different basis sets: {s}, {sp}, and {spd}. When viewed from the equilateral triangle and square geometries, the last electronic configuration, i.e. the {spd} one, appears to be most stable with respect to the geometrical deformations considered. In this case, the behaviour of the atoms of both clusters resembles that of hard spheres (i.e. close-packing).
Electron transfer from excited molecules of anthracene derivatives to methylviologen. Generation of the cation-radical and hydrogen
Authors: Řehák Viktor
Published: June 2010

The quantum yields of formation of the methylviologen cation-radical were measured, the effect of pH was studied, and the possibility of photogeneration of hydrogen was examined for systems with disodium 1,5- and 1,8-anthracenedisulphonate in aqueous media or 9-acetylanthracene in micellar media of sodium dodecyl sulphate, in the presence of methylviologen, triethanolamine, and colloidal platinum.
Preparation and properties of a new dalargine analogue L-Tyr-D-Ala-Gly-L-Phe-L-Tle-L-Arg
Authors: Pospíšek Jan , Bespalova Zhanna D. , Kovaříková Eva , Titov Michail I. , Barth Tomislav , Medzihradszky Kálmán
Published: June 2010

Stepwise synthesis in solution provided tert-butyloxycarbonyl-O-benzyl-L-tyrosyl-D-alanyl-glycyl-L-phenylalanyl-L-tert-leucyl-L-arginine which was then catalytically reduced and treated with trifluoroacetic acid. The product was purified by ion exchange chromatography and free electrophoresis. The hexapeptide containing L-tert-leucine in position 5 exhibited 63% biologic activity (guinea pig ileum) of Dalargine (L-Tyr-D-Ala-Gly-L-Phe-L-Leu-L-Arg).
α-Aminoacyl derivatives of α,ω-diaminopoly(oxyethylene)
Authors: Masař Bohumil , Schmidt Pavel , Pivcová Hana , Čefelín Pavel
Published: June 2010

By reacting p-nitrophenyl esters of L-α-amino acids with α-(3-aminopropyl)-ω-(aminomethyl)-poly(oxyethylene), diamides having the structure [X-NHCH(R)CONH]2Mx' were prepared, X being the protective group Boc or Z, R being residues of glutamic and aspartic acid, phenylalanine and tyrosine, and Mx' being the poly(oxyethylene) chain with the (-CH2)3- and -CH2- endgroups. The diamides were characterized by IR and 1H NMR spectroscopy and thin-layer chromatography. After complete removal of tert-butyloxycarbonyl groups from diamides (X = Boc), deprotected α-aminoacyl derivatives were characterized as trifluoroacetic acid salts.
Hydroboration of 1-(5-hexenyl)piperidine and trans–1-(3-hexenyl)piperidine
Authors: Kafka Stanislav , Kytner Jan , Šilhánková Alexandra , Ferles Miloslav
Published: June 2010

1-(5-Hexenyl)piperidine (Ia) and trans-1-(3-hexenyl)piperidine (Ib) were hydroborated with tetrahydrofuran-borane, diborane in situ, 9-borabicyclo[3.3.1]nonane and triethylamine-borane. The hydroboration products were converted to 1-piperidinylhexanols IIa-IIe by hydrolysis with hydrochloric acid and subsequent oxidation with hydrogen peroxide in an alkaline medium. In addition to the alcohols IIa-IIe, the reaction also gave 1-hexylpiperidine (Ic). In the reactions with diborane in situ and triethylamine-borane, thermal isomerization of the hydroboration products was also studied. Hydroboration of Ia with triethylamine-borane afforded a mixture of spirocyclic amine-boranes IIIa-IIIc from which 6-(1-piperidinyl)-3-hexylboronic acid hydrochloride (IV) was obtained by hydrolysis with hydrochloric acid. Compounds IIIa-IIIc were slowly decomposed with ethanol to give esters of boronic acids Id-If. The synthesis of compounds Ia and Ib is described.
Oxytocin analogues with non-coded amino acid residues in position 8: [8-Neopentylglycine]oxytocin and [8-cycloleucine]oxytocin
Authors: Hlaváček Jan , Pospíšek Jan , Slaninová Jiřina , Chan Walter Y. , Hruby Victor J.
Published: June 2010

[8-Neopentylglycine]oxytocin (II) and [8-cycloleucine]oxytocin (III) were prepared by a combination of solid-phase synthesis and fragment condensation. Both analogues exhibited decreased uterotonic potency in vitro, each being about 15-30% that of oxytocin. Analogue II also displayed similarly decreased uterotonic potency in vivo and galactogogic potency. On the other hand, analogue III exhibited almost the same potency as oxytocin in the uterotonic assay in vivo and in the galactogogic assay.
Theoretical and experimental investigation of the function of the wall flow deflecting ring. The determination of the optimum distance between deflecting rings
Authors: Semkov Krumm , Kolev Nikolai , Staněk Vladimír
Published: June 2010

Based on the earlier published mathematical model the problem has been solved of the optimum distance between the wall flow deflecting rings. These rings of small width placed near the wall of a packed column provide for the equality of the integral mean densities of irrigation in region near the column wall and in the bulk of the packing. An equation has been derived for the optimum distance between the wall flow deflecting rings convenient for practical calculations. A practical example has been used to show that the wall flow deflecting rings substantially improve the distribution of liquid in the column.
Determination of structure parameters of platinum hydrogenation catalysts and their supports
Authors: Růžička Jiří , Hanika Jiří , Sedláček Zdeněk , Růžička Vlastimil
Published: June 2010

Six catalysts containing 5 and 6.1 wt. % Pt were prepared by impregnation of activated carbon (Atlas AET 300) with H2PtCl6 from aqueous solutions and subsequent calcination and reduction with hydrogen at 100, 200, and 300 °C. The specific surface area was determined for the catalysts, saturated supports and the untreated support. The adsorption isotherms of n-pentane at 0 °C were measured for the support, saturated support and catalyst (100 °C), and the experimental data were correlated by the BET, Langmuir, and Dubinin equations; the pore radii distribution was also calculated for them. The activities of the catalysts were evaluated by measuring the initial reaction rates of hydrogenation of 1-octene and nitrobenzene.
Reduction and tensammetric pulse-polarographic currents of polynucleotides
Authors: Paleček Emil , Jelen František , Vetterl Vladimír
Published: June 2010

The behaviour of electrochemically reducible single-strand polynucleotides (poly(adenylic acid)) and poly(cytidylic acid)) was studied by the differential (derivative) pulse polarography (DPP) and by other methods. Measurements were performed with the help of the dropping mercury electrode under various conditions specified by the pulse width, pulse amplitude, drop time etc. For the faradaic and tensammetric DPP peaks the diagnostic criteria were proposed which make it possible to classify even very small DPP peaks of double helical polynucleotides.
Tautomerization of acetylacetone and relation of the tautomerization constant to other equilibrium parameters
Authors: Mollin Jiří , Dopitová Jitka , Staňková Oldřiška
Published: June 2010

The relative partial pressures of acetylacetone above mixed aqueous-organic solutions were measured chromatographically and the Gibbs energies of acetylacetone transfer from water to the mixed solvents were determined and separated into contributions from the keto and enol forms. The tautomerization equilibrium was related to other thermodynamic equilibria and the Gibbs energy of transfer of the keto form was correlated with that of acetone.
Arbuzov rearrangement in the reaction of arylmethylenemalonaldehydes with trimethyl phosphite: Formation of 2-(α-dimethoxyphosphonylbenzyl)-3-methoxyacroleins
Authors: Dvořák Dalimil , Šaman David , Buděšínský Miloš , Arnold Zdeněk
Published: June 2010

Reaction of arylmethylenemalonaldehydes I with trimethyl phosphite affords substituted methoxyacroleins V. The reaction proceeds via intermediates VII which, according to spectral data, can be described as interconverting dipolar and cyclic structures VIIA and VIIB, respectively. The intermediates VII are easily hydrolyzed to give the substituted malonaldehydes VI. Compounds VI were also obtained by acid-catalyzed hydrolysis of methoxyacroleins V.
COMPARISON OF A GENERAL SERIES EXPANSION METHOD AND THE HOMOTOPY ANALYSIS METHOD
Authors: LIU CHENG-SHI , LIU YANG
Published: June 2010

A simple analytic tool, namely the general series expansion method, is proposed to find the solutions for nonlinear differential equations. A set of suitable basis functions [Formula: see text] is chosen such that the solution to the equation can be expressed by [Formula: see text]. In general, t0 can control and adjust the convergence region of the series solution such that our method has the same effect as the homotopy analysis method proposed by Liao, but our method is simpler and clearer. As a result, we show that the secret parameter h in the homotopy analysis methods can be explained by using our parameter t0. Therefore, our method reveals a key secret in the homotopy analysis method. For the purpose of comparison with the homotopy analysis method, a typical example is studied in detail.
WHOLE GENOME COMPARISONS REVEALS A POSSIBLE CHIMERIC ORIGIN FOR A MAJOR METAZOAN ASSEMBLAGE
Authors: SYVANEN MICHAEL , DUCORE JONATHAN
Published: June 2010

The availability of whole genome sequences from multiple metazoan phyla is making it possible to determine their phylogeny. We have found that a sea urchin and human define a clade that excludes a tunicate, contradicting both classical and recent molecular studies that place the tunicate and vertebrate in the Chordate phylum. Intriguingly, by means of a novel four taxa analysis, we have partitioned the 2000 proteins responsible for this assignment into two groups. One group, containing about 40% of the proteins, supports the classical assemblage of the tunicate with vertebrates, while the remaining group places the tunicate outside of the chordate assemblage. The existence of these two phylogenetic groups is robustly maintained in five, six and nine taxa analyses. These results suggest that major horizontal gene transfer events occurred during the emergence of one of the metazoan phyla. The simplest explanation is that the modern tunicate (as represented by Ciona intestinalis) began as a hybrid between a primitive vertebrate and some other organism, perhaps from an extinct and unidentified protostome phylum, at a time close to but after the diversification of the chordates and echinoderms and before the lineages leading to Drosophila melanogaster and Caenorhabditis elegans diverged.
RELATIVE VON NEUMANN ENTROPY FOR EVALUATING AMINO ACID CONSERVATION
Authors: JOHANSSON FREDRIK , TOH HIROYUKI
Published: June 2010

The Shannon entropy is a common way of measuring conservation of sites in multiple sequence alignments, and has also been extended with the relative Shannon entropy to account for background frequencies. The von Neumann entropy is another extension of the Shannon entropy, adapted from quantum mechanics in order to account for amino acid similarities. However, there is yet no relative von Neumann entropy defined for sequence analysis.

We introduce a new definition of the von Neumann entropy for use in sequence analysis, which we found to perform better than the previous definition. We also introduce the relative von Neumann entropy and a way of parametrizing this in order to obtain the Shannon entropy, the relative Shannon entropy and the von Neumann entropy at special parameter values. We performed an exhaustive search of this parameter space and found better predictions of catalytic sites compared to any of the previously used entropies.
High-Mobility AlGaN/GaN Two-Dimensional Electron Gas Heterostructure Grown on (111) Single Crystal Diamond Substrate
Authors: Dussaigne Amélie , Gonschorek Marcus , Malinverni Marco , Py Marcel A. , Martin Denis , Mouti Anas , Stadelmann Pierre , Grandjean Nicolas
Published: June 2010

High mobility Al0.28Ga0.72N/GaN two-dimensional electron gas (2DEG) is achieved on (111) oriented single crystal diamond substrate. The surface morphology of the epilayer is free of cracks thanks to the use of an AlN interlayer for strain relaxation. The rms roughness of the sample surface deduced from atomic force microscopy is 0.6 nm for a 2 ×2 µm2scan area, which indicates an excellent surface morphology. Hall effect measurements reveal a 2DEG with room temperature mobility and sheet carrier density of 750 cm2V-1s-1and 1.4 ×1013cm-2, respectively. These results compare fairly well with AlGaN/GaN 2DEG characteristics obtained on other substrates like silicon and demonstrate that high power electronics can be developed on diamond substrates with high power dissipation capabilities.
Effects of Titania Surface Orientation on the Heterogeneous Formation of Barium Titanate by Hydrothermal Synthesis
Authors: Ryu Minoru , Suzuki Toshimasa , Kobayashi Keisuke , Sakashita Tatsuo , Mizuno Youichi
Published: June 2010

We investigated the mechanism of hydrothermal synthesis of BaTiO3 in the system of Ba(OH)2 and TiO2 in the early growth stage, based on model experiments using various single-crystal rutile TiO2 substrates with (001), (110), (100), and (101) orientations as starting reactants and a practical case study of widely utilized anatase TiO2 powder. The BaTiO3 products represented heterogeneous island growth directly on rutile TiO2 substrates and morphological features depending on the surface orientations of the substrates. Well-defined orientation relationships between BaTiO3 and the TiO2 substrate depended on the surface crystal planes of rutile TiO2 and were classified into four independent crystallographic types, including the unique topotaxial relationship already reported in barium diffusion-induced solid-state reactions. The hydrothermally treated anatase powder exhibited a dumbbell-like precipitation of BaTiO3 on the anatase TiO2 particles, preserving a crystallographic relationship of (001)[100] BaTiO3 ∥ (001)[100] anatase. The experimental findings revealed the heterogeneous dissolution–precipitation mechanism via surface orientation-dependent epitaxial growth of BaTiO3 directly on rutile and anatase TiO2 in the initial stage of hydrothermal reactions, suggesting the importance of controlling surface morphology and crystallinity of TiO2 as hydrothermal synthesis sources.
Phase Transformation and Electrical Properties of Bi2O3-Based ZnO Varistor Doped with WO3
Authors: Wan Shuai , Lu Wenzhong , Liu Wen
Published: June 2010

The effects of WO3 additive on the phase transformation, microstructure, varistor properties, and capacitance–voltage (C–V) characteristics of a Bi2O3-based ZnO varistor were investigated. A series of Bi2W
y
O3(1+y) (0≤y≤2/7) interstitial solid solutions were formed at the ZnO grain boundary when WO3 content (x) was in the range of 0–0.3 mol %, while the plate-like Bi2WO6 phases presented for further addition. The phase transformation between Bi2W
y
O3(1+y) (0≤y≤2/7) solid solutions and the Bi2WO6 phase at the ZnO grain boundary affects the microstructure and electrical properties of the varistor ceramic. WO3, involved in the formation of interfacial states or deep bulk traps at grain boundaries in the range of 0≤x≤0.3, provides large potential barriers to enhance the nonlinearity of a varistor ceramic. However, for x≥0.7, the present of the low resistive Bi2WO6 at the ZnO grain boundary results in a lowering of potential barriers and the deterioration of nonlinearity. The varistor ceramics for x=0.3 mol % exhibited the best performance: voltage gradient E
1mA=54.2 V/mm, nonlinear coefficient α=36, and leakage current I
L=0.8 µA, but changed to ohmic behavior for x=1.1 mol %.
Correlation of Microstructures and Conductivities of Ferroelectric Ceramics Using Complex Impedance Spectroscopy
Authors: Chen Pin-Yi , Chou Chen-Chia , Tseng Tseung-Yuen , Chen Haydn
Published: June 2010

The microstructures and conductivities of lead-free ceramics [Bi0.5(Na1-x
K
x
)0.5]TiO3 with x = 0.18 (BNKT) and lead-based ceramics of x(0.94PbZn1/3Nb2/3O3 + 0.06BaTiO3) + (1 - x)PbZr
y
Ti1-y
O3 with x = 0.5, y = 0.52 (PBZNZT) were investigated. Experimental results show that the activation energy of grain boundary conductivity is higher than that of grain conductivity for the BNKT system, indicating that the Bi2O3 evaporation of grains induces an easy conduction path through grains. However, the activation energy of grain boundary conductivity is lower than that of grain conductivity for the PBZNZT system, which might be attributed to the charged particles in the amorphous phase at grain boundaries, participating in the conduction process. A conduction model of both grain and grain boundary conductivities was proposed, and the microstructural characteristics and AC impedance data of ferroelectric ceramics correlate fairly well, suggesting that impedance spectroscopy is an efficient characterization technique for the grain boundary engineering of ferroelectric ceramics.
Scaling Behavior in Electric Current during Electrophoretic Deposition of Conjugated Polymer
Authors: Tada Kazuya , Onoda Mitsuyoshi
Published: June 2010

Electric currents during the electrophoretic deposition of a conjugated polymer in a thin slab vessel directly reflect the electrophoretic motion of polymer nanoparticles in suspensions. The double-logarithmic plot of the current profile was employed to estimate the transit time from the current profile, which is apparently featureless in the linear plot. The electrophoretic mobility was calculated to be 10-4–10-5cm2/(V·s), which tended to decrease with increasing polymer concentration in the suspension. The current profiles obtained at different voltages show a clear scaling behavior. That is, the dimensionless plots of the electric current profiles collapse onto a single curve. This result suggests that the diffusion of the colloidal particles due to the concentration gradient does not seem to play a major role in the present system.
Grain Boundary Evaluation of Cu(In1-xGax)Se2 Solar Cells
Authors: Kawamura Masahiro , Yamada Tomoyuki , Suyama Naoki , Yamada Akira , Konagai Makoto
Published: June 2010

The grain boundary (GB) properties of polycrystalline Cu(In1-x
,Ga
x
)Se2 (CIGS) have been characterized using electron beam-induced current (EBIC) measurements, electron backscatter diffraction (EBSD) patterns, and scanning spreading resistance microscopy (SSRM) measurements. The polished cross section of CIGS solar cells was evaluated by these three methods, and the surface EBIC image was obtained by scanning electron microscopy (SEM). A combination of the EBIC and EBSD techniques makes it possible to investigate the effect of the GBs on the minority carrier collection. Furthermore, the SSRM mapping enables the analysis of grain-by-grain carrier profiling by measuring the spreading resistance of CIGS solar cells. It was found from these results that the twin boundaries of CIGS grains do not contribute to carrier recombination. Furthermore, the brighter EBIC signals were observed at the GBs of CIGS, which showed that the produced electron–hole pairs easily separate from each other and that the minority carriers are repelled from the GBs. This remarkable property of the GBs is suitable for application of CIGS to solar cells.
Numerical Study on Signal Enhancement of the Rayleigh Wave in the Near-Field of Surface Defects
Authors: Guan Jianfei
Published: June 2010

The near-field scattering of laser generated Rayleigh waves from surface slot, which serves as artificial defects, has been studied using finite element method. Distinct signal enhancements of in- and out-of-plane displacement waveforms are observed in the near field of the surface slot, which enhance the detectability of the surface defect. Furthermore, the four interference phonomina in the displacement signals of surface acoustic waves have been captured and analyzed by considering the acoustic reflections and mode conversion happened at the defect. The results illustrate the physical mechanism which is responsible for the signal enhancement in the near field and the oscillations of signal enhancement factors for two directions as a function of the separation of the observation point and the defect tip.
Effects of Perovskite Additives on the Electromagnetic Properties of Z-Type Hexaferrites
Authors: Jia Lijun , Tang Yingming , Zhang Huaiwu , Deng Pingfeng , Liu Yingli , Liu Baoyuan
Published: June 2010

In order to modulate the electromagnetic properties of Z-type hexaferrites for high-frequency applications, perovskite additives have been introduced. The effects of these additives on the phase composition, densification, microstructures and electromagnetic properties of the ceramics have been investigated. The results indicate that Ba0.5Sr0.5TiO3 (BST) can promote the grain growth and enhance the sintering by increasing the displacement of ions due to the lattice distortion, which is a result of the solid solubility of Ti4+ in the hexaferrite. The increase of grain size and bulk density and the decrease of magnetocrystalline anisotropy give rise to the improvement of the static permeability. Meanwhile, the dielectric constant increases with BST content due to the changing of the valence of Fe ions in octahedral sites and the polarization of the perovskite phase. In contrast, Pb0.95Sr0.05(Zr0.52Ti0.48)O3 (PZT) is not effective for improving the electromagnetic properties of hexaferrites due to the strong coupling of Ti–O and Zr–O.
Lorentz Microscopy Study on Magnetization Reversal Process in Single-Domain State in Perovskite-Type Manganite
Authors: Mamishin Shuichi , Kasai Hiroto , Xia Weixing , Murakami Yasukazu , Shindo Daisuke , Mori Shigeo , Tonomura Akira
Published: June 2010

The phenomenon of ferromagnetic domain switching, which occurred in a colossal magnetoresistive manganite La0.25Pr0.375Ca0.375MnO3, was studied by sophisticated transmission electron microscopy techniques. Lorentz microscopy observations revealed the size dependence of the magnetization reversal behaviors. A small single-domain (70 nm) exhibited a direct switching process to another single-domain form, while a large single domain (150 nm) showed a multiple-domain configuration before the transformation to another single-domain state. We also demonstrated significant magnetic interaction in an assembly of single domains; i.e., neighboring single domains underwent magnetization reversal simultaneously. The results provide useful information for a deeper understanding of the switching process in a single-domain state, which can be observed in many advanced materials related to magnetic data storage media.
Floquet Scattering by Time-Periodic Potential in Double-Well with Spin–Orbit Coupling
Authors: Li Chun-Lei , Ye Bao-Sheng , Xu Yan , Zhang Yan-Xiang
Published: June 2010

We investigate the transmission properties of a single electron tunneling through a double quantum-well structure taking both a time-periodic potential and Dresselhaus spin–orbit coupling (DSOC) into consideration by using the single-band effective mass approximation method, the Floquet theorem, and the transfer-matrix technique. Our numerical results show that some satellite resonant peaks appear in both the two sides of those field-free resonant peaks, owing to the photon-assisted transmission in the presence of the time-periodic potential. The applied bias potential will shift the transmission resonant peaks toward lower energy region and the spin degeneracy is eliminated when the DSOC is considered. The spin polarization can be controlled by tuning the in-plane wave vector and the applied electric field.
A New Low Temperature Polycrystalline Silicon Thin Film Transistor Pixel Circuit for Active Matrix Organic Light Emitting Diode
Authors: Fan Ching-Lin , Lin Yi-Yan , Chang Jyu-Yu , Sun Bo-Jhang , Liu Yan-Wei
Published: June 2010

This study presents one novel compensation pixel design and driving method for active matrix organic light-emitting diode (AMOLED) displays that use low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs) with a voltage feed-back method and the simulation results are proposed and verified by SPICE simulator. The measurement and simulation of LTPS TFT characteristics demonstrate the good fitting result. The proposed circuit consists of four TFTs and two capacitors with an additional signal line. The error rates of OLED anode voltage variation are below 0.3% under the threshold voltage deviation of driving TFT (ΔV
TH = ±0.33 V). The simulation results show that the pixel design can improve the display image non-uniformity by compensating the threshold voltage deviation of driving TFT and the degradation of OLED threshold voltage at the same time.
Thermoelectric Effects of Multiple Quantum Dot Junctions in the Nonlinear Response Regime
Authors: Kuo David M.-T. , Chang Yia-Chung
Published: June 2010

The thermoelectric effects of semiconductor quantum dots (QDs) embedded into an insulator matrix connected to metallic electrodes are theoretically investigated in the nonlinear response regime. A multilevel Anderson model is used to simulate the multiple QDs junction system. The charge and heat currents in the sequential tunneling process are calculated by the Keldysh Green's function technique. We have demonstrated that thermal rectification and negative differential thermal conductance behaviors can be observed for the multiple QD junction system in the absence of phonon heat current.
Characterization of Pad–Wafer Contact and Surface Topography in Chemical Mechanical Planarization Using Laser Confocal Microscopy
Authors: Sun Ting , Zhuang Yun , Borucki Leonard , Philipossian Ara
Published: June 2010

In this study, an optical method using laser confocal microscopy was developed to measure the surface contact area and topography of pads under a dry and static condition. A custom-made pad sample holder with a sapphire window and a miniature load cell was used to collect pad surface contact images at controlled loads. By extracting the black spots in the collected images, pad contact area and contact summit density were obtained. The analysis of a post polishing pad sample (8,289×921 µm2) showed that the contact area increased from 0.026 to 0.045% when the pressure increased from 2 to 4 psi and increased further to 0.059% when the pressure increased to 6 psi. The contact summit density also exhibited a linear increase with the applied pressure. The above results were consistent with the Greenwood and Williamson theory, which predicted a linear relationship between pad contact area and contact summit density. Laser confocal microscopy was also used to measure pad surface topography by establishing probability density functions (PDFs) of pad surface height.
Highly Sensitive Detection of Defects in Piping Using Multireflecting Guided Wave Energy Trapping Method
Authors: Nishino Hideo , Ogura Keiji , Tanaka Toshiro , Yoshida Kenichi
Published: June 2010

A multireflecting guided wave energy trapping (MGET) method has been developed for the highly sensitive detection of defects in a pipe using a guided wave. The MGET method enhances the amplitude of a defect signal using two wave reflectors. In the MGET method, the two reflectors are set at both ends of a region of piping to be inspected, and a guided wave is generated, which propagates in the region of inspection. With this setup, multireflection can be observed between the two reflectors. If a defect exists in the region, the amplitude of the defect signal increases owing to the increase in the number of reflections at the reflectors because n combinations of multiple propagation paths having the same path length exist in the defect signal after n reflections. Details of the principle of the MGET method and its experimental verification are reported. The sensitivity of the MGET method is about 10 times higher than that of the conventional guided wave method. The efficiency of the method is quantitatively discussed by considering a simple mathematical model together with the experimental results.
Silicon Wafer Cleaning Using New Liquid Aerosol with Controlled Droplet Velocity and Size by Rotary Atomizer Method
Authors: Seike Yoshiyuki , Miyachi Keiji , Shibata Tatsuo , Kobayashi Yoshinori , Kurokawa Syuhei , Doi Toshiro
Published: June 2010

A liquid aerosol, which sprays cleaning liquid with a carrier gas, is widely used for cleaning semiconductor devices. The liquid aerosol using a conventional two-fluid nozzle may cause pattern damage on the wafer. To resolve this problem, we have made a prototype new rotary atomizing two-fluid cleaning nozzle (RAC nozzle), which can control the velocity distribution and size distribution of flying liquid droplets separately. It was confirmed by measuring flying liquid droplets using a shadow Doppler particle analyzer system that the mean volumetric diameter of the droplets could be atomized to 20 µm or less at a rotational speed of the air turbine of 50,000 min-1 and that the mean velocity of the flying liquid droplets could be controlled in the range under 65 m/s independently. It was confirmed in a cleaning experiment using polystyrene latex (PSL) particles on a wafer that particle removal efficiency increased when shaping air pressure increased. Also, the particle removal efficiency was improved with the finer atomization promoted by a higher rotational speed of the air turbine.
Impact of Thin Island-Like BaSi2 Template on the Formation of n+-BaSi2/p+-Si Tunnel Junction on Si(111) Surface by Molecular Beam Epitaxy
Authors: Saito Takanobu , Matsumoto Yuta , Sasaki Ryo , Takeishi Michitoshi , Suemasu Takashi
Published: June 2010

We have grown n+-BaSi2/p+-Si tunnel junctions with different BaSi2 template layer thicknesses by molecular beam epitaxy. Even when the template layer was 1 nm in thickness, which was not actually a continuous film but small islands, they act as seed crystals for the initiation of overlayer growth. The electrical resistance of the junctions increased with template thickness. Both epitaxial growth and low resistance were achieved for thin island-like BaSi2 templates.
Response of Lead Zirconate Titanate without Poling to High-Energy Heavy-Ion Beam
Authors: Takechi Seiji , Morinaga Shin-ya , Kurozumi Atsuma , Uno Takefumi , Miyachi Takashi , Okudaira Osamu , Fujii Masayuki , Hasebe Nobuyuki , Shibata Hiromi , Murakami Takeshi , Uchihori Yukio , Okada Nagaya
Published: June 2010

A radiation detector based on the piezoelectric effect, which is fabricated using lead zirconate titanate (PZT), has been investigated by irradiating it with a 400 MeV/n xenon (Xe) beam. To estimate quantitatively the electric charge appearing on the PZT detector, the detector made of PZT without poling was used in this study. It was found that the sensitivity of the detector without poling was reduced by ∼1/20 compared with that of the detector with poling within the limits of the experimental conditions.
Modeling Optical Lithography Physics
Authors: Neureuther Andrew R. , Rubinstein Juliet , Chin Eric , Wang Lynn , Miller Marshal , Clifford Chris , Yamazoe Kenji
Published: June 2010

Key physical phenomena associated with resists, illumination, lenses and masks are used to show the progress in models and algorithms for modeling optical projection printing as well as current simulation challenges in managing process complexity for manufacturing. The amazing current capability and challenges for projection printing are discussed using the 22 nm device generation. A fundamental foundation for modeling resist exposure, partial coherent imaging and defect printability is given. The technology innovations of resolution enhancement and chemically amplified resist systems and their modeling challenges are overviewed. Automated chip-level applications in pattern pre-compensation and design-anticipation of residual process variations require new simulation approaches.
Fundamental Study of the Mask Topography Effect on the Advanced Phase-Shifting Masks for Next-Generation Lithography
Authors: Yuito Takashi , Misaka Akio , Sasago Masaru
Published: June 2010

Phase-shifting masks (PSMs) with trench- or mesa-type quartz etched structure are widely known as powerful resolution enhancement technologies for advanced lithography. For advanced PSMs, the feature size on a mask including a phase shifter is beyond the wavelength of the light source, and for such a sub-wavelength phase shifter, the impact of the mask topography effect on the amount of phase shifting and the light transmittance becomes prominent. However, an effective method of measuring the actual phase shifting and transmittance of such a tiny phase shifter has not yet been reported because of the difficulty in measuring the sub-wavelength structure. In this work, we have attempted to measure the actual transmittance and phase shifting using the assembled tiny phase shifter aperture array pattern, and we have successfully revealed the actual transmittance and phase shifting behavior of the tiny phase shifter depending on its feature size and trench depth.
Full-Chip Layout Optimization for Process Margin Enhancement Using Model-Based Hotspot Fixing System
Authors: Kobayashi Sachiko , Kyoh Suigen , Kotani Toshiya , Takekawa Yoko , Inoue Soichi , Nakamae Koji
Published: June 2010

As the design rule of integrated circuits is shrinking rapidly, it is necessary to use low-k
1 lithography technologies. With low-k
1 lithography, even if aggressive optical proximity correction is adopted, many sites become marginless spots, known as “hotspots”. For this problem, hotspot fixer (HSF) in design-for-manufacturability flow has been studied. In our previous work, we indicated the feasibility of layout modification using a simple line/space sizing rule for metal layers in 65-nm-node logic devices. However, in view of the continuous design-rule shrinkage and design complication, a more flexible modification method has become necessary to fix various types of hotspots. In this work, we have developed a brute-force model-based HSF. To further reduce the processing time, the hybrid flow of rule- and model-based HSFs is studied. The feasibility of such hybrid flow is studied by applying it to the full-chip layout modification of a logic test chip.
Resolution Enhancement for Beyond-22-nm Node Using Extreme Ultraviolet Exposure Tool
Authors: Tawarayama Kazuo , Aoyama Hajime , Matsunaga Kentaro , Magoshi Shunko , Arisawa Yukiyasu , Uno Taiga
Published: June 2010

EUV1 is a full-field extreme-ultraviolet (EUV) exposure tool that was manufactured by Nikon and is being developed at Selete. Its lithographic performance was evaluated in scanning exposure experiments using line-and-space (L&S) patterns, Selete Standard Resist 4 (SSR4), a numerical aperture (NA) of 0.25, and conventional illumination (σ=0.8). Results show that 28 nm L&S patterns are resolved and that the critical dimension (CD) uniformity across a shot is 3.7 nm. Simulations predict that the use of dipole illumination will push the resolution limit down to a half pitch of 20 nm for L&S patterns. Moreover, the results of test site exposures using dipole illumination indicate that the EUV1 is suitable for device fabrication beyond the 22 nm node.
Actinic Phase Defect Detection for Extreme Ultraviolet Lithography Mask with Absorber Patterns
Authors: Terasawa Tsuneo , Yamane Takeshi , Tanaka Toshihiko , Suga Osamu , Tomie Toshihisa
Published: June 2010

An actinic (at-wavelength) dark-field inspection tool was developed for detecting phase defects over the full area of a multilayer coated extreme ultraviolet lithography (EUVL) mask blank. This tool was also used for inspecting EUVL mask with absorber patterns. To understand the effect of absorber patterns on dark-field inspection signals, a test mask with programmed phase defects and absorber lines with periodic patterns was fabricated and inspected. Simulated and experimental results showed that the absorber lines increased the background intensity of inspection signals, whereas the intensity of the phase defect signals remained almost unchanged. The level of the background intensity of the inspection signal for absorber lines (128–180 nm wide) was approximately 10 times higher than that for mask blank signals without absorbers. Although increased background resulted in a decrease in the defect's signal-to-background ratio, the signal from the phase defect was still brighter in comparison to its surrounding area.
Ion Track Nanolithography Using Thick Cross-Linked Poly(methyl methacrylate) 950 Photoresist
Authors: Koukharenko Elena , Kuleshova Jekaterina , Fowler Marcel , Kok Stephen L. , Tudor Michael J. , Beeby Stephen P. , Nandhakumar Iris , White Neil M.
Published: June 2010

This study shows that poly(methyl methacrylate) (PMMA) 950 thick photoresist is a promising polymer for ion-track nanolithography templates for nanomaterials fabrication resulting in high aspect ratio nanostructures ranging from 100 to 500 with highly selective etch rates when using deep ultraviolet (DUV) cross linking polymerisation prior to the ion-track irradiation. DUV exposure times and post exposure hardbake conditions are crucial factors for achieving high aspect ratio structures. Exposure doses of 6600 mJ/cm2with post exposure hardbake at 180 °C for 90 s gave promising preliminary results for high aspect ratio nanotemplates using thick layer of PMMA 950 photoresist.
Analysis of Resist Surface Deformation during Electron Beam Irradiation
Authors: Kotera Masatoshi , Akiba Yasuhito
Published: June 2010

It is known that polymers mostly shrink during observation by scanning electron microscope. However, resist surface deformation during electron beam irradiation has not been discussed in electron beam lithography. In the present study, poly(methyl methacrylate) (PMMA) film is taken as an example of polymers, and the surface deformation by electron beam irradiation is measured by atomic force microscope. Exposure dose varies in a range to obtain the exposure intensity distribution (EID) curve for point exposure, that is from 10-11to 10-6C at an acceleration voltage of 20 kV. Even at a dose of 5×10-10C, where a contribution of backscattered electrons from the Si substrate becomes significant in the distribution, a dimple of around 1 µm radius and around 30 nm depth is produced. The EID curve derived from the experiment might be influenced by the deformation. Assuming that the development process starts from this deformed surface, it should be a serious problem in lithography, especially for low-sensitivity resists. The deformation is not only shrinkage, but also deposition along the beam axis for the resists. In the present study, the surface deformation is analyzed in terms of the electron-beam-induced shrinkage and deposition. A simulation model is presented to quantify the mechanism, and the range of its validity is discussed.
Relationship between Normalized Image Log Slope and Chemical Gradient in Chemically Amplified Extreme Ultraviolet Resists
Authors: Kozawa Takahiro , Tagawa Seiichi
Published: June 2010

In lithography, normalized image log slope (NILS) is an important metric that describes the quality of an aerial image of incident photons. The aerial image is converted to a latent image through lithographic processes in the resist. The quality of the latent image correlates with line edge roughness (LER). Chemical gradient is also an important metric that describes the quality of a latent image. In this study, we investigated the relationship between NILS and chemical gradient in chemically amplified resists for extreme ultraviolet lithography. In particular, the effect of effective reaction radius for catalytic chain reactions on the relationship between NILS and chemical gradient was clarified.
Logic Gates Based on Carbon Nanotube Field-Effect Transistors with SiNx Passivation Films
Authors: Kishimoto Takaomi , Ohno Yasuhide , Maehashi Kenzo , Inoue Koichi , Matsumoto Kazuhiko
Published: June 2010

We demonstrated logic gates based on complementary carbon nanotube field-effect transistors (CNT-FETs) with SiN
x
passivation films deposited by catalytic chemical vapor deposition. The carrier type of CNT-FETs was controlled by forming SiN
x
passivation films. Electrical measurements revealed that the p-type characteristics of CNT-FETs were converted to n-type characteristics after the deposition of SiN
x
passivation films. Then, the n-type CNT-FETs with SiN
x
passivation films were reconverted to p-type CNT-FETs by annealing in N2 atmosphere. As a consequence, complementary voltage inverters comprising p- and n-type CNT-FETs with SiN
x
passivation films were demonstrated on the same SiO2 substrate by conventional photolithography and lift-off techniques. Moreover, the static transfer and dynamic characteristics of the CNT-FET-based inverters were investigated. It was found that a gain of approximately 3 was achieved and that the device was switched properly at frequencies of up to 100 Hz.
Voltage Transfer Characteristics in GaAs-Based Three-Branch Nanowire Junctions Controlled by Schottky Wrap Gates
Authors: Nakata Daisuke , Shibata Hiromu , Shiratori Yuta , Kasai Seiya
Published: June 2010

Nonlinear voltage transfer characteristics in GaAs-based three-branch nanowire junctions (TBJs) controlled by Schottky wrap gates (WPGs) are investigated by characterization of the gate voltage and size dependences in detail. WPGs squeezed the nanowires only in the node portion and modulated the curve only in the low-input-voltage region. When the entire nanowire was narrowed geometrically, the voltage transfer curve became abrupt in a wide voltage range. On the other hand, the nanowire length affected only the curve in the high-input-voltage region. These results indicate that the voltage transfer characteristics of the WPG-controlled TBJ device in the low- and high-voltage regions are controlled by the junction node with WPGs and the end of the positively biased nanowire, respectively. The observed behaviors can be understood in terms of a surface-potential-induced field domain model.
Low-Loss Photonic Crystal Defect Waveguides and Taper Designs in InP/InGaAsP for Transverse Magnetic Polarized Light
Authors: Ma Ping , Kaspar Peter , Jäckel Heinz
Published: June 2010

We present the simulation, fabrication and characterization of novel low-loss photonic crystal (PhC) defect waveguides for transverse magnetic (TM) polarized light in the InP/InGaAsP material system. Minimal propagation losses for the proposed W4 PhC waveguides as low as ∼300 dB/cm at λ= 1550 nm for lattice constant a = 350 nm, and ∼500 dB/cm at λ= 1532 nm for lattice constant a = 590 nm are obtained from the cut-back analysis. In addition, an associated application of proposed wide PhC waveguides as intermediate short tapers between deeply etched access waveguides and narrower quasi-single-mode PhC waveguides is investigated. Predicted improved coupling efficiency has been validated experimentally.