bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Si-Jun-Zi decoction polysaccharides on cell migration and gene expression in wounded rat intestinal epithelial cells
Authors: Liu L. , Han L. , Wong Daisy Y. L. , Yue Patrick Y. K. , Ha W. Y. , Hu Y. H. , Wang P. X. , Wong Ricky N. S.
Published: February 2005

Si-Jun-Zi decoction (SJZD), a traditional Chinese herbal prescription, has been used clinically for treating patients with disorders of the digestive system. Previous studies indicated that the polysaccharides of SJZD (SJZPS) are the active components contributing towards its pharmacological effects in improving gastrointestinal function and immunity. However, the protective and restitutive effects on intestinal epithelial cells remain unknown. In the present study, SJZPS were first extracted and chemically characterized. Then their stimulatory and restitutive effects on intestinal epithelial cells (IEC-6 cells) were elicited by differentin vitromodels including migration of wounded IEC-6 cells and cell proliferation. Results indicated that SJZPS not only protects the cells against the harmful impairment of indomethacin but also enhances re-epithelialization of a wounded monolayer at an optimal dose of 100 μg/ml at 24 h incubation. To elucidate the modulatory effect of SJZPS on wounded IEC-6 cells at the molecular level, an oligonucleotide microarray was employed to study differential gene expression of SJZPS-treated IEC-6 cells and the candidate genes were validated by RT-PCR. There was increased expression of genes coding for ion channels and transporters, which are critical to cell migration and restoration of wounded intestinal cells, suggesting a possible mechanism for re-epithelialization. In conclusion, our data show for the first time that SJZPS can enhance intestinal restitution and protect against indomethacin-induced damage of intestinal epithelial cells. These findings provide new insight into the mechanism of action of a traditional Chinese herbal prescription, SJZD, in intestinal wound restitution.
A Member of the Sugar Transporter Family, Stl1p Is the Glycerol/H+Symporter inSaccharomyces cerevisiae
Authors: Ferreira Célia , van Voorst Frank , Martins António , Neves Luisa , Oliveira Rui , Kielland-Brandt Morten C. , Lucas Cândida , Brandt Anders
Published: February 2005

Glycerol and other polyols are used as osmoprotectants by many organisms. Several yeasts and other fungi can take up glycerol by proton symport. To identify genes involved in active glycerol uptake in Saccharomyces cerevisiae we screened a deletion mutant collection comprising 321 genes encoding proteins with 6 or more predicted transmembrane domains for impaired growth on glycerol medium. Deletion of STL1, which encodes a member of the sugar transporter family, eliminates active glycerol transport. Stl1p is present in the plasma membrane in S. cerevisiae during conditions where glycerol symport is functional. Both the Stl1 protein and the active glycerol transport are subject to glucose-induced inactivation, following identical patterns. Furthermore, the Stl1 protein and the glycerol symporter activity are strongly but transiently induced when cells are subjected to osmotic shock. STL1 was heterologously expressed in Schizosaccharomyces pombe, a yeast that does not contain its own active glycerol transport system. In S. pombe, STL1 conferred the ability to take up glycerol against a concentration gradient in a proton motive force-dependent manner. We conclude that the glycerol proton symporter in S. cerevisiae is encoded by STL1.
Thuja occidentalis (Arbor vitae): A Review of its Pharmaceutical, Pharmacological and Clinical Properties
Authors: Naser Belal , Bodinet Cornelia , Tegtmeier Martin , Lindequist Ulrike
Published: February 2005

Arbor vitae (Thuja occidentalis L.) is a native European tree widely used in homeopathy and evidence‐based phytotherapy. Many reviews and monographs have been published on the herbal substance′s description, mode of action and clinical use. However, no comprehensive evidence‐based review is available. Therefore, our aim was to search MEDLINE databases and survey manufacturers for further details or unpublished data. This review presents the botany, ethnobotany and phytochemistry, especially the different contents of essential oil (Thujone) in relation to different extraction procedures of this medicinal plant. Thuja′s antiviral action and immunopharmacological potential, such as stimulatory and co‐stimulatory effects on cytokine and antibody production and activation of macrophages and other immunocompetent cells, have been evaluated in numerous in vitro and in vivo investigations. Although no controlled trials have been conducted on Thuja occ alone, many clinical studies have been performed with a herbal medicinal product containing a special extract of Thuja occ and other immunostimulants, demonstrating its therapeutic efficacy and safety in respiratory tract infections.
Inheritance of female mating preference in a sympatric sibling species pair of Lake Victoria cichlids: implications for speciation
Authors: P. Haesler Marcel , Seehausen Ole
Published: February 2005

Female mate choice has often been proposed to play an important role in cases of rapid speciation, in particular in the explosively evolved haplochromine cichlid species flocks of the Great Lakes of East Africa. Little, if anything, is known in cichlid radiations about the heritability of female mating preferences. Entirely sympatric distribution, large ecological overlap and conspicuous differences in male nuptial coloration, and female preferences for these, make the sister speciesPundamilia pundamiliaandP. nyerereifrom Lake Victoria an ideally suited species pair to test assumptions on the genetics of mating preferences made in models of sympatric speciation. Female mate choice is necessary and sufficient to maintain reproductive isolation between these species, and it is perhaps not unlikely therefore, that female mate choice has been important during speciation. A prerequisite for this, which had remained untested in African cichlid fish, is that variation in female mating preferences is heritable. We investigated mating preferences of females of these sister species and their hybrids to test this assumption of most sympatric speciation models, and to further test the assumption of some models of sympatric speciation by sexual selection that female preference is a single–gene trait. We find that the differences in female mating preferences between the sister species are heritable, possibly with quite high heritabilities, and that few but probably more than one genetic loci contribute to this behavioural speciation trait with no apparent dominance. We discuss these results in the light of speciation models and the debate about the explosive radiation of cichlid fishes in Lake Victoria.
Generational Accounting and the Saving Rate Decline, 1960–2000
Authors: Eschker Erick
Published: February 2005

Government agencies in 26 countries construct generational accounts, defined as the present value of remaining lifetime net taxes that a generation can expect to pay. This paper calculates generational accounts for the United States, 1960–2000, and finds that generational account changes do not coincide with the abrupt decline in the saving rate that began in the mid‐1980s. First, transfers to the elderly, as reflected in changes to the generational accounts, increased gradually after 1960. Second, the fiscal burden placed on future generations, measured both in real terms and relative to newborns, was no higher in 2000 than in 1960.
Improved synthesis of 5‐hydroxylysine (Hyl) derivatives*
Authors: Cudic M. , Lauer‐Fields J.L. , Fields G. B.
Published: February 2005

Abstract:  The synthesis of 5‐hydroxylysine (Hyl) derivatives for incorporation by solid‐phase methodologies presents numerous challenges. Hyl readily undergoes intramolecular lactone formation, and protected intermediates often have poor solubilities. The goals of this work were twofold: first, develop a convenient method for the synthesis of O‐protected Fmoc‐Hyl; secondly, evaluate the efficiency of methods for the synthesis of O‐glycosylated Fmoc‐Hyl. The 5‐O‐tert‐butyldimethylsilyl (TBDMS) fluoren‐9‐ylmethoxycarbonyl‐Hyl (Fmoc‐Hyl) derivative was conveniently prepared by the addition of tert‐butyldimethylsilyl trifluoromethanesulfonate to copper‐complexed Hyl[ɛ‐tert‐butyloxycarbonyl (Boc)]. The complex was decomposed with Na+ Chelex resin and the Fmoc group added to the α‐amino group. Fmoc‐Hyl(ɛ‐Boc, O‐TBDMS) was obtained in 67% overall yield and successfully used for the solid‐phase syntheses of 3 Hyl‐containing peptides. The preparation of Fmoc‐Hyl[ɛ‐Boc, O‐(2,3,4,6‐tetra‐O‐acetyl‐β‐d‐galactopyranosyl)] was compared for the thioglycoside, trichloroacetimidate and Koenigs–Knorr methods. The most efficient approach was found to be Koenigs–Knorr under inverse conditions, where Fmoc‐Hyl(ɛ‐Boc)‐OBzl and peracetylated galactosyl bromide were added to silver trifluoromethanesulfonate in 1,2‐dichloroethane, resulting in a 45% isolated yield. Side‐reactions that occurred during previously described preparations of glycosylated Hyl derivatives, such as lactone formation, loss of side‐chain protecting groups, orthoester formation, or production of anomeric mixtures, were avoided here. Research on the enzymology of Lys hydroxylation and subsequent glycosylation, as well as the role of glycosylated Hyl in receptor recognition, will be greatly aided by the convenient and efficient synthetic methods developed here.
Recognition and signal transduction mechanism of Escherichia coli heat‐stable enterotoxin and its receptor, guanylate cyclase C
Authors: Hasegawa M. , Shimonishi Y.
Published: February 2005

Abstract:  Guanylate cyclase C (GC‐C), a member of the membrane‐bound GC family, consists of an extracellular domain (ECD) and an intracellular domain, which are connected by a single‐transmembrane region. GC‐C is a receptor protein, i.e. specifically stimulated by the endogenous peptides guanylin, uroguanylin, lymphoguanylin, and the exogenous peptide heat‐stable enterotoxin (STa), secreted by pathogenic Escherichia coli and acting on the intestinal brush border membranes. The binding of these peptide ligands to the ECD of GC‐C results in the synthesis of cyclic GMP in cells, which, in turn, regulates a variety of intracellular physiologic processes. As the cloning of GC‐C, its physiologic functions of each domain have been vigorously investigated. The structural characterization of the ligand‐binding domain of the receptor promises to provide important clues for better understanding of the mechanisms of receptor recognition and activation. Recently, structural data for each domain of membrane‐bound GCs and related proteins has become available. Coupling information obtained from such work and validation of structure–function relationships of GC‐C and its ligands should allow for three‐dimensional mapping of their interaction site in detail. Our approach to this issue involved designing photoaffinity‐labeling STa analogs, capable of binding covalently to the ligand‐binding region of the ECD of GC‐C. The photoaffinity‐labeling ligand was used to covalently label a soluble form of the recombinant ECD protein. Mass spectrometric analyses of an endoproteinase digest of the ECD revealed that the ligand specifically bound to a narrow region contained in the membrane‐proximal subdomain of the ECD of GC‐C. These results will enable us to identify the possible binding motifs within the ligand‐binding domain by computer modeling. In this review, we summarize the available data on the recognition mechanism between STa and GC‐C at the molecular level.
Synthesis and biological activity of GnRH antagonists modified at position 3 with 3‐(2‐methoxy‐5‐pyridyl)‐alanine*
Authors: Samant M.P. , Miller C. , Hong D.J. , Koerber S.C. , Croston G. , Rivier C.L. , Rivier J.E.
Published: February 2005

Abstract:  Degarelix is a potent very long‐acting GnRH antagonist after subcutaneous administration. In this paper, we describe the synthesis of two analogs of degarelix incorporating racemic 3‐(2‐methoxy‐5‐pyridyl)‐alanine (2‐OMe‐5Pal, 5) at position 3. The two diastereomers were separated by reverse‐phase high‐performance liquid chromatography (RP‐HPLC) and the absolute stereochemistry at position 3 in the peptides was determined by enzymatic digestion with proteinase K. These analogs were tested in vitro for their ability to antagonize the GnRH receptor and in vivo for duration of action in a castrated male rat assay. Analog 7 with D2‐OMe‐5Pal was potent in vitro (IC50 = 5.22 nm); however, analog 8 with L2‐OMe‐5Pal at position 3 in degarelix lost potency as an antagonist of the human GnRH receptor (IC50 = 36.95 nm). Both the analogs were found to be short‐acting in vivo.
U–Pb zircon geochronology of Late Devonian to Early Carboniferous extension‐related silicic volcanism in the northern New England Fold Belt*
Authors: BRYAN S. E. , ALLEN C. M. , HOLCOMBE R. J. , FIELDING C. R.
Published: February 2005

Laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) analysis of zircons confirm a Late Devonian to Early Carboniferous age (ca 360–350 Ma) for silicic volcanic rocks of the Campwyn Volcanics and Yarrol terrane of the northern New England Fold Belt (Queensland). These rocks are coeval with silicic volcanism recorded elsewhere in the fold belt at this time (Connors Arch, Drummond Basin). The new U–Pb zircon ages, in combination with those from previous studies, show that silicic magmatism was both widespread across the northern New England Fold Belt (>250 000 km2 and ≥500 km inboard of plate margin) and protracted, occurring over a period of ∼15 million years. Zircon inheritance is commonplace in the Late Devonian – Early Carboniferous volcanics, reflecting anatectic melting and considerable reworking of continental crust. Inherited zircon components range from ca 370 to ca 2050 Ma, with Middle Devonian (385–370 Ma) zircons being common to almost all dated units. Precambrian zircon components record either Precambrian crystalline crust or sedimentary accumulations that were present above or within the zone of magma formation. This contrasts with a lack of significant zircon inheritance in younger Permo‐Carboniferous igneous rocks intruded through, and emplaced on top of, the Devonian–Carboniferous successions. The inheritance data and location of these volcanic rocks at the eastern margins of the northern New England Fold Belt, coupled with Sr–Nd, Pb isotopic data and depleted mantle model ages for Late Palaeozoic and Mesozoic magmatism, imply that Precambrian mafic and felsic crustal materials (potentially as old as 2050 Ma), or at the very least Lower Palaeozoic rocks derived from the reworking of Precambrian rocks, comprise basement to the eastern parts of the fold belt. This crustal basement architecture may be a relict from the Late Proterozoic breakup of the Rodinian supercontinent.
Clinical decision‐making and myocardial viability: current perspectives
Authors: Nelson C. , Marwick T. H.
Published: February 2005

Abstract

Not all myocardium involved in a myocardial infarction is dead or irreversibly damaged. The balance between the amount of scar and live tissue, and the nature of the live tissue, determine the likelihood that contractile function will improve after revascularisation. This improvement (which defines viability) may be predicted with about 80% accuracy using several techniques. This review examines the determinants of functional recovery and how they may be integrated in making decisions regarding revascularisation. (Intern Med J 2005; 35: 118–125)
Manual Therapies in the Management of Tension‐Type Headache
Authors: Fernández‐de‐las‐Peñas Cesar , Alonso‐Blanco Cristina , Cuadrado Maria Luz , Miangolarra Juan Carlos , Barriga Francisco Javier , Pareja Juan A.
Published: February 2005

Patients suffering from tension‐type headache (TTH) are often treated with manual therapies. We have analyzed the quality and the outcomes of published trials and have not found any rigorous evidence that manual therapies are effective in TTH. Further research is required before manual therapies can be considered useful in the management of TTH.
Clarification of Social Support
Authors: Finfgeld‐Connett Deborah
Published: February 2005

Purpose:

To clarify the concept of social support.

Design:

Template Verification and Expansion Model.

Methods:

Meta‐synthesis strategies.

Findings:

Social support is composed of emotional and instrumental support. It is an advocative interpersonal process characterized by reciprocal exchange of information, it is context specific, and it results in improved mental health. Antecedents of emotional and instrumental support include a perceived need plus a social network and climate that are conducive to the exchange of social support.

Conclusions:

In keeping with the nonprofessional nature of social support, nurses are advised to encourage patients to use and enhance personal support networks. For the same reason, nurses should reconsider investigating social support as a nursing intervention. Expanded efforts are needed to differentiate social support from concepts such as caring.
Translation and Validation of the Condom Self‐Efficacy Scale With Thai Adolescents and Young Adults
Authors: Thato Sathja , Hanna Kathleen M. , Rodcumdee Branom
Published: February 2005

Purpose:

To translate the 14‐item Condom Self‐Efficacy Scale (CSES) into Thai and to validate the Thai version of the Condom Self‐efficacy Scale (CSES‐T) among Thai adolescents and young adults.

Methods:

The CSES was translated using a back‐translation technique and validated with a cluster‐based sample of 425 participants aged 18 to 22 years from eight randomly selected private vocational schools in Bangkok. Participants completed anonymous self‐administered scales. Principal component analysis with varimax rotation was conducted to identify latent factors.

Results:

Factor analysis indicated three factors: communication, correct use, and consistent use. Items loading on the original CSES also loaded on the same factors of the CSES‐T except one item. The Cronbach's alpha coefficients were .85 for the total scale, .70 for consistent use, .79 for correct use, and .80 for communication.

Conclusions:

Based on psychometric properties, the CSES‐T is a valid and reliable tool. It is culturally appropriate for Thai young adults. Thai researchers and health care providers can use the CSES‐T to assess adolescents' and young adults' self‐efficacy to use condoms as well as to further develop and evaluate interventions to increase condom use.
Measurement of the electrical conductivity of metallic tubes by studying magnetic screening at low frequency
Authors: Íñiguez J. , Raposo V. , Flores A. G. , Zazo M. , Hernández-López A.
Published: February 2005

We discuss a technique for measuring the electrical conductivity in metallic tubes based on Faraday’s induction law. A detailed study of magnetic screening in the low frequency approximation leads to expressions that relate the screening coefficient to the geometry, magnetic permeability, and conductivity of the metallic tubes. We discuss experimental results for different tubes.
Shell Composition Has No Net Impact on Large-Scale Evolutionary Patterns in Mollusks
Authors: Kidwell Susan M.
Published: February 2005

A major suspected bias in the fossil record of skeletonized groups is variation in preservability owing to differences in shell composition. However, despite extensive changes in shell composition over the 500-million-year history of marine bivalves, genus duration and shell composition show few significant relationships, and of those, virtually all are contrary to bias from preferential loss of highly reactive shell types. Distortion of large-scale temporal patterns in marine bivalves owing to preservability is thus apparently weak or randomly distributed, which increases the likelihood that observed patterns in this and other shelled groups carry a strong biological signal.
The Quantum Measurement Problem
Authors: Leggett A. J.
Published: February 2005

Despite the spectacular success of quantum mechanics (QM) over the last 80 years in explaining phenomena observed at the atomic and subatomic level, the conceptual status of the theory is still a topic of lively controversy. Most of the discussion centers around two famous paradoxes (or, as some would have it, pseudoparadoxes) associated, respectively, with the names of Einstein, Podolsky, and Rosen (EPR) and with Schrödinger's cat. In this Viewpoint, I will concentrate on the paradox of Schrödinger's cat or, as it is often known (to my mind somewhat misleadingly), the quantum measurement paradox.
Circular Polarization Resonator based on Cholesteric Liquid Crystal
Authors: Tanaka Yosuke , Takano Hiroyuki , Kurokawa Takashi
Published: February 2005

As a basic study of a novel organic vertical cavity surface emitting laser (VCSEL) with cholesteric liquid crystal (CLC) mirrors, the resonance characteristics of a passive CLC cavity are investigated theoretically and experimentally. The analysis based on Maxwell wave equations clarifies the properties of the optical field in the resonator and the effects of refractive index on resonance characteristics. CLC mirrors fabricated by photopolymerizing the mixture of chiral monoacrylate, nematic liquid crystal, and photoinitiator show a reflectance of 73% for the left-handed circular polarization light at 638 nm. A Fabry–Perot resonator based on these CLC mirrors induces the resonance of left-handed circular polarization. The finesse and the FSR of this resonator are 9.2 and 56.3 pm, respectively, which agree well with the theoretical predictions.
The Electro-Optic Properties of a Fast Response, Three-Electrode Liquid Crystal Device
Authors: Xiang C. Y. , Sun X. W. , Guo J. X. , Yin X. J. , Qi G. J.
Published: February 2005

The optical properties of a new hybrid aligned nematic liquid crystal (LC) device (Jpn. J. Appl. Phys. 42 (2003) L763) with three-electrode structure for fast response applications have been systematically studied. The transmission shows a clear dependence on the electrode structure, the bias voltage and LC material. The highest transmittance is obtained by optimizing the electrode structure and the bias voltage for a certain cell gap and LC material. The response time is dependent on LC material, but is not sensitive to the bias voltage and cell structure in our experiment.
Molecular Beam Study of H2O Interaction with Pt(111)
Authors: Kondo Takahiro , Mori Daisuke , Okada Ryuta , Yamamoto Shigehiko
Published: February 2005

We have developed a highly stable supersonic H2O molecular beam and examined its properties by time-of-flight technique. A wide range of incident kinetic energy E

i
of 340–730 meV with ΔE/E of 0.2–0.3 and 77–163 meV with ΔE/E of 0.4–0.6 is achieved by seeding He and He+Ar, respectively. The incident kinetic energy dependence of the angular intensity distributions of H2O scattered from Pt(111) at 500 K is measured in order to understand the inelastic scattering process of H2O on Pt(111). The comparisons of H2O scattering with Ne scattering from Pt(111) and with the prediction of the simple classical binary collision model reveal that not only phonon creation in the surface but also a large amount of H2O rotational mode excitation and/or chattering scattering takes place during collision, particularly for high incident kinetic energy conditions.
Experimental Analysis of the Improved Emission Properties of Glassy β-eucryptite Ion Source
Authors: Oliveira Rogério de Moraes , Gonçalves José Américo Neves , Ueda Mário , Beloto Antônio Fernando
Published: February 2005

In this paper we describe an experiment in which a tenfold increase on the Li+ emission of β-eucryptite compound was obtained after its transformation from pasty to glassy form. Detailed procedure for preparation of this glassy compound is also described. The analysis of the crystal structure of both loads was carried out by X-ray diffraction, resulting in the determination of a greater volume for the unit cell of the glassy ion source with the observation of the changed axial ratios of the crystallographic directions a and c. The modified parameters of the unit cell can explain the better ion emission properties of the glassy compound.
High-Response i-InAs/n-GaAs Quantum-Dot Infrared Photodetector with No Current Blocking Barrier
Authors: Lee Sang Jun , Noh Sam Kyu , Choe Jung Woo , Lee Uk Hyun , Hong Sung Chul , Lee Jung Il
Published: February 2005

We report a high-response normal-incidence infrared photodetector based on the bound-to-continuum transition fabricated on the self-assembled i-InAs/n-GaAs quantum-dot (QD) heterostructure doped in GaAs barrier with no current blocking barrier. The photoresponse characteristics have been confirmed by distinct methods using a SiC globar source and a blackbody radiation source. From the blackbody system, the responsivity of 1750 mA/W at a peak wavelength of ∼4.7 µm (21 K) has been achieved, which is much higher than that reported on the n-InAs/i-GaAs QD-based infrared photodetectors doped in QDs with additional barrier.
Characterizing Metal-Oxide Semiconductor Structures Consisting of HfSiOx as Gate Dielectrics using Monoenergetic Positron Beams
Authors: Uedono Akira , Hattori Nobuyoshi , Ogura Atsushi , Kudo Jun , Nishikawa Satoshi , Ohdaira Toshiyuki , Suzuki Ryoichi , Mikado Tomohisa
Published: February 2005

Metal–oxide–semiconductor structures consisting of HfSiO
x
as the gate dielectric were characterized by using monoenergetic positron beams. 200-nm-thick polycrystalline-Si (poly-Si) and 5-nm HfSiO
x
films were grown on Si substrates by chemical vapor deposition. Doppler broadening spectra of the annihilation radiation and the lifetime spectra of positrons were measured as a function of incident positron energy for ion-implanted and unimplanted samples. For the unimplanted sample after rapid thermal annealing (RTA: 1030°C, 10 s), the lifetime of positrons in the HfSiO
x
film was 448±2 ps. Since the obtained lifetime was longer than the lifetime of positrons trapped by point defects in metal oxides, the positrons in HfSiO
x
films were considered to annihilate from the trapped state by open spaces which exist intrinsically in their amorphous structure. After P+, As+ and BF2
+-implantation into the poly-Si film and RTA, the lifetime of positrons was 420–430 ps. This decrease in the lifetime was attributed to the shrinkage of the open spaces in the HfSiO
x
film due to the accumulation of implanted impurities in the film during RTA. The diffusion length of positrons in Si substrates was found to depend on the implanted species of ions. This fact was attributed to the electric field introduced by charged defects in the HfSiO
x
films.
Reduction of Hollow Defects in 6H-SiC Single Crystals Grown by Sublimation Boule Growth Technique on (1120) 6H-SiC Substrates
Authors: Nishiguchi Taro , Masuda Yasuichi , Ohshima Satoru , Nishino Shigehiro
Published: February 2005

Sublimation boule growth of 6H-SiC on (1120) 6H-SiC substrates was investigated. Hollow defects were generated in the crystals grown on (1120) substrates, and they penetrated along the growth direction to the as-grown surface. A new growth model of SiC on (1120) SiC substrates that distinguishes between two-dimensional growth and three-dimensional growth is proposed. The generation of both the stacking faults and the hollow defects on (1120) substrates was attributable to the three-dimensional growth. The growth conditions were modified and applied to suppress the generation of hollow defects. These conditions included the reduction of the growth temperature in the initial stage of the growth, and the increase of the nitrogen concentration in the vapor phase. Due to the changes in the growth conditions, the density of the hollow defects on (1120) substrates was reduced by one order of magnitude to approximately 103 cm-2. An atomically flat as-grown surface was obtained by the sublimation boule growth technique in nitrogen ambient.
Universal Visible Antireflection Coating Designs for Various Substrates
Authors: Liou Yeuh-Yeong
Published: February 2005

A design procedure, based on the flip-flop tuning search algorithm, is applied to design universal visible antireflection coatings for various substrates with indices 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75 and 1.784. The universal broadband antireflection coating designs obtained by the flip-flop tuning method for a two-material and a three-material system with 80 sublayers of 300 nm thickness starting at high index and middle index lead to 10-layer structures, and the average reflectivities of these designs for the eight different substrates over the entire visible spectral region (400–750 nm) decrease to lower than 0.199% and 0.201%, respectively. Although the antireflection performance for each substrate is somewhat less than the optimum, it is acceptable for most applications.
Two-Photon Absorption and Optical Limiting Properties of Organic Salt trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium Iodide in Various Solvents
Authors: He Guohua , Wang Gang , Meng Ruiping , Cui Yiping
Published: February 2005

The absorption spectra, single-photon induced fluorescence spectra, two-photon absorption (TPA) and optical limiting behaviors of organic dye trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium iodide (abbreviated as ASPI) have been studied in three solvents [chloroform, benzyl alcohol, dimethyl formamide (DMF)] with different polarities. The optical properties of ASPI were found to be strongly influenced by the solvents used. With increasing polarity of the solvents, the absorption and fluorescence peaks of ASPI solutions exhibit marked blue and red shifts, respectively, and the effective TPA cross sections and the optical limiting effects decrease. The TPA cross sections of ASPI measured in the three solvents are 3.41×10-47 (chloroform), 1.86×10-48 (benzyl alcohol) and 1.05×10-48 (DMF) cm4·s·photon-1.
Far-Field Pattern Analysis for an Array Grating Compressor
Authors: Harimoto Tetsuo
Published: February 2005

A numerical analysis for far-field pattern distribution of an array grating compressor showed that alignment of segmental gratings can be achieved by adjusting only two tilted angles and the relative position distance of two segmental gratings. An alignment tolerance criterion was set up with a simple formula for an array grating with the size of meter order. For the example of an array grating with a size of 0.5 m, the angular and position tolerances are required to be 0.25 µrad and λ/13, respectively.
Feedback Control for Accurate Shaping of Ultrashort Optical Pulses prior to Chirped Pulse Amplification
Authors: Tanabe Takasumi , Ohno Kimihisa , Okamoto Tatuyoshi , Yamanaka Mio , Kannari Fumihiko
Published: February 2005

Through experiments, we demonstrate accurate pulse shaping of femtosecond optical pulses in both amplitude and phase, prior to chirped pulse amplification. The nonlinear transfer function of the amplifier was compensated with feedback control referring to the amplified pulse shape measured by frequency resolved optical gating (FROG) or temporal analysis, by dispersing a pair of light e fields (TADPOLE). In FROG-referring control, the pulse shaper is adaptively controlled using a control index calculated from the two-dimensional FROG trace image, while in TADPOLE-referring control, the shaping phase-mask is corrected only a few times using the reconstructed spectrum phase of the output pulse. The performance and limitations of pre-shaping systems are discussed by comparing two pulse shaper devices, namely a liquid-crystal spatial light modulator and an acoustic optical phase dispersion filter, two pulse measurement techniques, and two feedback control schemes.
Thermoluminescence of X-Ray-Irradiated CdS-Doped Glass
Authors: Miyoshi Tadaki , Kawamura Takashi , Kobayashi Takanobu , Shinohara Taketsugu , Takeshita Tsuyoshi , Takahashi Yutaka , Tamechika Masakatsu , Tokuda Nobuko , Fukumoto Tetsuo , Kaneda Teruhisa
Published: February 2005

Thermoluminescence has been observed in X-ray-irradiated CdS-doped glass. The intensity of thermoluminescence is proportional to the X-ray dose up to 10 Gy. The intensity of thermoluminescence for Asahi Y-44 is approximately 0.5% of that of phosphor for a commercial radiation dosimeter: MSO-S (Mg2SiO4:Tb). Photofading of Y-44 is markedly lower than that for MSO-S.
Visualization of Topological Microstructures of Mesoporous Silicate Hollow Sphere with Confocal Microscopy
Authors: Mou Chung-Yuan , Yang Te-Chen , Lin Hong-ping , Kao Fu-Jen
Published: February 2005

We demonstrate the use of confocal fluorescence microscopy in visualizing the exotic 3D topological structure of pillared-hollow spheres of mesoporous silicates. The mesoporous structures are labeled by rhodamine 6G dye to facilitate visualization. The optical sectioning capability and noninvasiveness of confocal microscopy not only further clarifies these hollow spheres' unique topological structure but also enables mapping of their genus distribution.
Hyperon Scattering Experiments with a New Tracking Detector “SCITIC”
Authors: Asai Jyunkichi , Fukuda Tomokazu , Ieiri Masaharu , Imai Kenichi , Imoto Wataru , Iwata Soma , Kadowaki Tetsuhito , Kurosawa Maki , Maruta Tomofumi , Nagae Tomofumi , Noumi Hiroyuki , Saha Planab Kumar , Sato Akira , Takahashi Hitoshi , Yoon Choong Jae , Nakai Kozi
Published: February 2005

A new tracking detector, scintillating track image camera (SCITIC) was used for hyperon-scattering experiments. Since the hyperon lifetimes are short, the low-energy hyperon-nucleon scattering can be studied only with a track detector used as an active target. The present experiment has shown that the SCITIC is a promising detector for the hyperon scattering experiments. Polarized hyperons Σ+ were produced through p(π+, K+)Σ+ reactions with a 1.6 GeV/c pion beam on a liquid scintillator of the active target. Three sets of SCITIC were used to record the pictures of Σ+ production and scattering. A kaon spectrometer was used to trigger the SCITIC with a signal of kaon from the reaction. Left/right asymmetries of the Σ+p scattering were determined through analyses of the pictorial data, and the results were in accordance with a quark-model prediction that the asymmetry was large in the Σ+p scattering while it was small in the ΛN case.
Novel Nondestructive Readout Methods For Near-field Optical Recording with Large Refractive Index Modulation in Amorphous Diarylethene Layer
Authors: Maruyama Hideki , Kawai Tsuyoshi , Kim Myeong-Suk , Irie Masahiro
Published: February 2005

Novel nondestructive readout methods for near-field optical recording has been demonstrated with an amorphous photochromic film. Large refractive index change of an amorphous photochromic layer of 1,2-bis(5-(2,4-diphenylphenyl)-2,4-dimethyl-3-thienyl) perfluorocyclopentene induced by the photochromic reactions is detected by the use of a guided-wave mode and a substrate radiation mode with near-IR laser light. The modulation amplitude in the reflected light intensity before and after the photo-bleaching reaction was as high as 20%.
New Scheme of Electrostatic Discharge Circuit Simulations Using Protection Device Model with Generated-Hole-Dependent Base Resistance
Authors: Tosaka Yoshiharu , Anzai Hiromi , Suzuki Kunihiro , Oka Hideki
Published: February 2005

Circuit simulations are important for examining the design of electrostatic discharge (ESD) protections. A new scheme of ESD circuit simulations using an equivalent circuit model for metal oxide semiconductor (MOS) protection devices is introduced. Our equivalent circuit model, which includes generated-hole-dependent base resistance, properly describes the snapback characteristics of ESD protection devices and, thus, our scheme is applicable for designing ESD protection circuits. Simulation results using our scheme for the protection circuit with multifinger MOS devices agreed well with measured snapback characteristics. These results show the effectiveness of our ESD circuit simulation technology.
Quantitative Examination of Mobility Lowering Associated with Ultrathin Gate Oxides in Silicon Metal-Oxide-Semiconductor Inversion Layer
Authors: Koga Junji , Ishihara Takamitsu , Takagi Shin-ichi
Published: February 2005

In this study, mobility lowering inherent to ultrathin gate oxides is experimentally examined in the silicon metal-oxide-semiconductor (Si MOS) inversion layer, and additional scattering mechanisms associated with gate oxide scaling are discussed, paying attention to the extraction of reliable experimental data on inversion-layer mobility. It is found that poly-Si-gate impurity concentration strongly affects the mobility lowering associated with ultrathin gate oxides, which is quantitatively discriminated from that of Coulomb scattering due to substrate impurities and interface states. This finding indicates the contribution of remote Coulomb scattering due to the gate impurities. In addition, low-temperature measurements reveal that roughness scattering is enhanced, possibly because of the poor Si/SiO2 interface in the initial stage of oxide growth. Therefore, further gate oxide scaling down to 1.5 nm or less can cause remote Coulomb scattering as well as enhanced roughness scattering, resulting in the saturation or decrease in the drive current capability.
Ni Precursor for Chemical Vapor Deposition of NiSi
Authors: Ishikawa Masato , Kada Takeshi , Machida Hideaki , Ohshita Yoshio , Ogura Atsushi
Published: February 2005

Nickel thin film is an attractive material for use as electrodes or contacts of metal oxide semiconductor field effect transistors (MOSFETs), and numerous studies have focused on Ni monosilicide (NiSi). Bis-methylcyclopentadienyl-nickel [(MeCp)2Ni] is a dark green solid at room temperature, which becomes liquid at 36°C. Thermogravimetric differential thermal analysis (TGDTA) measurements revealed that most of the (MeCp)2Ni is vaporized without thermal decomposition and it decomposes from 200°C to 250°C. (MeCp)2Ni has a low viscosity and a high vapor pressure (1 Torr at 73°C), and its transportability is sufficiently good for it to be used as a chemical vapor deposition (CVD) precursor. Ni was deposited at 300°C by CVD using a (MeCp)2Ni/H2 gas system. Ni reacted with the Si substrate, and X-ray diffraction (XRD) analysis showed that a part of the silicides had formed on the Si substrate. Si3H8 injection prevents the Si substrate from being consumed by the silicide reaction, and a conformal NiSi film with a flat interface on the Si substrate was obtained.
Effects of Post Dielectric Deposition and Post Metallization Annealing Processes on Metal/Dy2O3/Si(100) Diode Characteristics
Authors: Ohmi Shun-ichiro , Yamamoto Hiroyuki , Taguchi Junichi , Tsutsui Kazuo , Iwai Hiroshi
Published: February 2005

Ultra-high vacuum annealing was investigated for Dy2O3 films deposited on Si(100) substrates. The leakage current of the Dy2O3 films deposited at room temperature (RT) was found to be decreased without any increase of the equivalent oxide thickness (EOT) by the in-situ vacuum annealing method compared to that of the conventional rapid thermal annealing (RTA) in O2. The negative flat-band voltage (V
FB) shift observed after the in-situ vacuum annealing process was suppressed by increasing the deposition temperature of Dy2O3 on chemically oxidized Si from RT to 250°C. The EOT of 1.1 nm with the leakage current of 0.29 A/cm2 (@V
FB+1 V) was obtained for the Dy2O3 film after the air-brake and vacuum annealing, and the EOT of 0.63 nm with 4 A/cm2 (@V
FB+1 V) was achieved for the Dy2O3 film with the TaN gate electrode after the post metallization annealing (PMA).
30 nm Triple-Gate In0.7GaAs HEMTs Fabricated by Damage-Free SiO2/SiNx Sidewall Process and BCB Planarization
Authors: Kim Dae-Hyun , Yeon Seong-Jin , Lee Jae-Hak , Seo Kwang-Seok
Published: February 2005

A 30 nm In0.7GaAs high electron mobility transistor (HEMT) with triple-gate has been successfully fabricated using the SiO2/SiN
x
sidewall process and BCB planarization. The sidewall gate process was used to obtain finer lines, and the width of the initial line could be lessened to half by this process. To fill the Schottky metal effectively to a narrow gate line after applying the developed sidewall process, the sputtered tungsten (W) metal was utilized instead of conventional e-beam evaporated metal. To reduce the parasitic capacitance through dielectric layers and the gate metal resistance (R
g), the etched-back BCB with a low dielectric constant was used as the supporting layer of a wide gate head, which also offered extremely low R
g of 1.7 Ohm for a total gate width (W
g) of 2×100 µm. The fabricated 30 nm In0.7GaAs HEMTs showed V
th of -0.4 V, G
m,max of 1.7 S/mm, and f
T of 421 GHz. These results indicate that InGaAs nano-HEMT with excellent device performance could be successfully fabricated through a reproducible and damage-free sidewall process without the aid of state-of-the-art lithography equipment. We also believe that the developed process will be directly applicable to the fabrication of deep sub-50 nm InGaAs HEMTs if the initial line length can be reduced to below 50 nm order.
Improvement of High-Speed Oxide-Confined Vertical-Cavity Surface-Emitting Lasers
Authors: Yu Hsin-Chieh , Chang Shoou-Jinn , Su Yan-Kuin , Sung Chia-Pin , Yang Hong-Pin , Huang Chun-Yuan , Lin Yu-Wei , Wang Jin-Mei , Lai Fang-I , Kuo Hao-Chung
Published: February 2005

High-speed vertical-cavity surface-emitting lasers that could be modulated up to 10 Giga-bit-per-second (Gbps) were accomplished by using additional proton implantation to reduce the parasitic capacitance. The eye diagram of the implanted device shows a noticeable improvement when compared with those devices without implantation. In contrast to previous reports, moreover, the output power-current-voltage (L-I-V) characteristics of the fabricated devices in this study show excellent consistency between before and after implantation. The high-temperature lifetime of devices fabricated with a similar process has already exceeded 8100 h up to the present day.
Suppression of Lasing Wavelength Change of 980 nm Pump Laser Diodes for Metro Applications
Authors: Kawasaki Kazushige , Shigihara Kimio , Matsuoka Hiromasu , Kunitsugu Yasuhiro , Yamamura Shin'ichi , Yagi Tetsuya , Omura Etsuji , Mitsui Yasuo
Published: February 2005

High-power 980 nm laser diodes (LDs) are used as pumping sources of erbium-doped fiber amplifiers (EDFAs). Reductions of costs and power consumption in EDFAs are very important for access or metro applications. System construction without fiber Bragg gratings (FBGs) and thermal electric coolers (TECs) is strongly required. Therefore, high-power 980 nm LDs with small lasing wavelength changes under various operational conditions are highly desired in these systems. We proposed a new technique of wavelength change suppression using a facet coating for 980 nm LDs. Less than one-third reduction of lasing wavelength change was realized by this method. Moreover, the proposed LDs possess more than 350 mW output power even at 95°C and good reliability at 50°C with 700 mA automatic current control (ACC).
Intersubband Transition Based on a Novel II-VI Quantum Well Structure for Ultrafast All-Optical Switching
Authors: Akimoto Ryoichi , Li Bing Sheng , Sasaki Fumio , Hasama Toshifumi
Published: February 2005

We have achieved intersubband absorption as short as 1.58 µm in (CdS/ZnSe)/BeTe quantum wells (QWs) by employing relatively thicker BeTe barriers of 10 monolayers, covering an optical communication wavelength of 1.55 µm within its absorption band. The ISB carrier relaxation was investigated by means of femtosecond one-color pump and probe measurement at the ISB absorption peak position for samples with various well widths. The ISB carrier relaxation time of 270 fs was observed in the sample with the absorption peak at 1.82 µm. The slow decay component with a time constant of 2–4 ps, which has been observed in ZnSe/BeTe QWs, was not observed in the (CdS/ZnSe)/BeTe QWs, indicating that the Γ(ZnSe)-X(BeTe) electron transfer is suppressed as expected from the band alignment. For applications toward ultrafast all-optical switching devices, a ridge-waveguide structure composed of (CdS/ZnSe)/BeTe QWs active and ZnMgBeSe cladding layers is proposed. Refractive indices of these layers have been examined and these data are fed to design ridge-waveguide structures. As a first step, a slab waveguide structure has been successfully grown.
Control of InxGa1-xAs Capping Layer Induced Optical Polarization in Edge-Emitting Photoluminescence of InAs Quantum Dots
Authors: Jayavel Pachamuthu , Tanaka Hirokazu , Kita Takashi , Wada Osamu , Ebe Hiroji , Sugawara Mitsuru , Tatebayashi Jun , Arakawa Yasuhiko , Nakata Yoshiaki , Akiyama Tomoyuki
Published: February 2005

We report polarization properties of InAs self-assembled quantum dots (QD) observed from cleaved-edge photoluminescence (PL) of the dots. Transverse-electric (TE) and transverse-magnetic (TM) mode intensities were monitored for dots having In composition of x=0 and 0.13. TE-mode intensity for dots with x=0 is much larger than TM-mode intensity. On the other hand, for x=0.13, TM-mode intensity is dominant, i.e., the polarization is inverted. The results indicate that the polarization anisotropy of the dots in the active region of the waveguide structure can be controlled by the capping layer In compositions.
High Performance Electroluminescence from Nanocrystalline Silicon with Carbon Buffer
Authors: Gelloz Bernard , Koshida Nobuyoshi
Published: February 2005

Efficient electroluminescence (EL) is obtained at low voltages (3 V) from n+-type silicon/electrochemically oxidized thin nanocrystalline porous silicon (PS)/amorphous carbon/indium tin oxide (ITO) junctions. The carbon film acts as an efficient mechanical and electrical buffer layer between PS and ITO. As a result, the efficiency, stability and reproducibility are markedly enhanced. High efficiency and high brightness have been made possible at low voltages. A diode exhibiting top performance in several parameters has been obtained. A brightness of 3 Cd/m2 has been achieved at 3 V for an external power efficiency of 0.35%. For the first time, voltage-tunable one-peak EL spectra have been obtained. This phenomenon originates from the EL excitation mechanism and the diode high efficiency at low voltages. The EL stability is also enhanced due to the capping function of the carbon film, and the high chemical stability of carbon and Si-C bonds.
Femtosecond Pulse Propagation through a Quantum Wire Optical Waveguide Observed by Cross-Correlation Frequency-Resolved Optical Gating Spectroscopy
Authors: Tsurumachi Noriaki , Watanabe Naoki , Hikosaka Kazunori , Wang Xue-Lun , Komori Kazuhiro , Hattori Toshiaki , Ogura Mutsuo
Published: February 2005

Femtosecond optical pulse propagation in a quantum wire (QWR) waveguide was investigated by two-color sum-frequency cross-correlation frequency-resolved optical gating (XFROG) spectroscopy. The polarization anisotropy of the crescent-shaped GaAs QWR was observed in terms of absorption and refractive index dispersion by XFROG spectroscopy.
Selective Molecular Beam Epitaxy Growth of GaAs Hexagonal Nanowire Networks on (111)B Patterned Substrates
Authors: Yoshida Souichi , Tamai Isao , Sato Taketomo , Hasegawa Hideki
Published: February 2005

In view of applications to hexagonal binary decision diagram (BDD) quantum circuits, the growth of hexagonal GaAs nanowire networks was attempted by selective molecular beam epitaxy (MBE) on (111)B prepatterned substrates. The basic feasibility of <112>-oriented straight nanowires was first investigated. GaAs nanowires were selectively formed on the top (111)B plane of AlGaAs mesa structures with high uniformity. The lateral width of the wires was determined by two facet boundary planes separating the growth regions on the top and the side facets of the mesa structures. The angle of the boundary planes remained constant during growth, resulting in the wire width being precisely controlled by the thickness of the AlGaAs barrier layer. Then, GaAs/AlGaAs hexagonal nanowire networks were grown on the patterned substrates consisting of three equivalent <112>-oriented wires for a (111)B plane. The results of detailed structural and optical studies showed that highly uniform and smoothly connected hexagonal nanowire networks having threefold symmetry were successfully fabricated by the present selective MBE growth technique.