bluuebunny/crossref_metadata_2025 huggingface dataset:
Cefoxitin, a Semisynthetic Cephamycin Antibiotic: Resistance to Beta-Lactamase Inactivation
Authors: Onishi H. Russell , Daoust Donald R. , Zimmerman Sheldon B. , Hendlin David , Stapley Edward O.
Published: June 2012

Cefoxitin is a new, cephalosporin-like antibiotic which is highly resistant to hydrolysis by β-lactamase. Ninety-one cultures were selected either for their general resistance to cephalosporin antibiotics or for their ability to produce β-lactamase. Some of these cultures were resistant to cefoxitin. The capacity of each of the 91 strains to hydrolyze cefoxitin with β-lactamase was determined. Only seven of the cultures degraded the antibiotic as determined by a general assay for β-lactamase. Several others were able to hydrolyze cefoxitin after enzyme was induced by low concentrations of the antibiotic. The role of the constitutive and inducible enzyme in bacterial resistance to the antibiotic was investigated. Enzymatic destruction of cefoxitin was found to be an important factor contributing to bacterial resistance. However, the complete and rapid degradation of cefoxitin is not essential to resistance since one strain,
Enterobacter cloacae
1316, hydrolyzed the antibiotic very slowly but was able to grow unaffected in the presence of cefoxitin. The presence of the enzyme is not necessarily sufficient to confer resistance since another culture,
Klebsiella
D535, readily hydrolyzed the antibiotic but was susceptible to it.
Methods for Evaluating Topical Antibacterial Agents on Human Skin
Authors: Marples R. R. , Kligman A. M.
Published: June 2012

Three procedures were presented for appraising the ability of antibacterial chemicals and formulations to suppress the growth of microorganisms on human skin. In each of these, the microflora was quantified after the skin had been occlusively covered for a day or more, a circumstance which, in the absence of a deterrent, led to an explosive overgrowth by resident organisms. The data obtained related to (i) the capacity to prevent expansion of the normal microflora, (ii) the suppression of an already expanded flora, and (iii) the persistence of antibacterial effect 3 days after the last application.
Antimicrobial Susceptibility of
Haemophilus influenzae
Authors: Thornsberry Clyde , Kirven Linda A.
Published: June 2012

Selected clinical isolates of
Haemophilus influenzae
were tested for their susceptibility to seven antibiotics by a microtiter broth dilution and an agar diffusion method. Eleven of 40 strains tested were resistant to ampicillin, the drug of choice, by both methods. All the strains tested were susceptible to chloramphenicol, and all but one were susceptible to tetracycline. Of the other four antibiotics tested, the ranges of minimal inhibitory concentrations (MICs) were: 0.5 to 4 μg of gentamicin per ml, 0.5 to 4 μg of erythromycin per ml, and 2 to 16 μg of clindamycin per ml. MICs of ampicillin for both the susceptible and resistant strains were markedly affected by inoculum concentration. The ampicillin MICs of the resistant strains were also affected by the time of incubation.
Pipemidic Acid, a New Antibacterial Agent Active Against
Pseudomonas aeruginosa
: In Vitro Properties
Authors: Shimizu Masanao , Takase Yoshiyuki , Nakamura Shinichi , Katae Hiromi , Minami Akira , Nakata Katsuhisa , Inoue Satoru , Ishiyama Masamitsu , Kubo Yuji
Published: June 2012

Pipemidic acid, 8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)-pyrido [2,3-
d
]pyrimidine-6-carboxylic acid, is a new derivative of piromidic acid. It is active against gram-negative bacteria including
Pseudomonas aeruginosa
as well as some gram-positive bacteria. Its potency is generally greater than that of piromidic acid and nalidixic acid. Cross-resistance is not observed between pipemidic acid and various antibiotics, and most of bacteria resistant to piromidic acid and nalidixic acid are moderately susceptible to pipemidic acid. The activity of pipemidic acid is scarcely affected by the addition of serum, sodium cholate, or change of medium pH, but is subject to the influence of inoculum size. Its action is bactericidal above minimal inhibitory concentrations.
Mineral Nutrition of
Streptomyces kanamyceticus
for Kanamycin Formation
Authors: Basak Ketaki , Majumdar S. K.
Published: June 2012

Kanamycin production by
Streptomyces kanamyceticus
ATCC 12853 requires magnesium sulfate and potassium phosphate at concentrations of 0.4 and 1.0 g per liter, respectively. The optimal concentrations of Fe and Zn for production of kanamycin are 0.25 and 0.575 μg/ml, respectively, whereas Mo at 0.04 μg/ml allows maximal cellular growth and antibiotic synthesis. Mn and Ca are without any effect. Cu, Co, Ni, and V have inhibitory effect on growth of the organism as well as kanamycin formation.
In Vitro and Clinical Studies of Cefatrizine, a New Semisynthetic Cephalosporin
Authors: Busto Ramon Del , Haas Erwin , Madhavan Tom , Burch Keith , Cox Frank , Fisher Evelyn , Quinn Edward , Pohlod Donald
Published: June 2012

Cefatrizine, a new oral semisynthetic cephalosporin, was evaluated in vitro and in the treatment of 18 patients with acute urinary tract infection, pneumonia, and soft tissue infection. In vitro, it was more active than cephalexin for gram-positive and gram-negative bacteria. It was also more active than cephalothin, cefazolin, and cephapirin against most of the gram-negative bacteria but less active against the gram-positive bacteria. Of the patients treated with cefatrizine, only one failed to respond. This patient had pneumococcal conjunctivitis and hypogammaglobulinemia and neutropenia. The mean peak serum level after multiple 6-hourly doses of 500 mg was 6.2 μg/ml. The serum levels of cefatrizine necessary for inhibition of most susceptible organisms were well within the achievable range. The drug was well tolerated, and no renal, hepatic, or hematological toxicity was detected.
Effects of Ampicillin-Amikacin and Ampicillin-Rifampin on Enterococci
Authors: Iannini Paul B. , Ehret Josephine , Eickhoff Theodore C.
Published: June 2012

Fifty-seven clinical isolates of enterococcus were tested for susceptibility to 10 antibiotics in a microtiter broth dilution system. Amoxicillin, ampicillin, vancomycin, and rifampin inhibited all strains at concentrations easily achievable in blood. Resistance to rifampin developed rapidly. Of the aminoglycosides, gentamicin was most active, followed in decreasing order by tobramycin, amikacin, kanamycin, and streptomycin. High-level resistance to streptomycin was present in 26% of the strains and to kanamycin in 23% of the strains. Growth curve studies of selected strains revealed synergy with ampicillin-amikacin and antagonism with ampicillin-rifampin. It is suggested that ampicillin-gentamicin constitutes adequate initial therapy for enterococcal infections until the results of tests for high-level resistance to kanamycin and streptomycin are known and that clinical trails of ampicillin-amikacin are warranted.
In Vitro and In Vivo Activities of Minocycline and Other Antibiotics Against
Acinetobacter
(
Herellea-Mima
)
Authors: Kuck N. A.
Published: June 2012

Minocycline was the most active of six antibiotics tested against 65 clinical isolates of
Acinetobacter calcoaceticus
(syn.:
Herellea, Mima
) received from six medical centers. In the Bauer-Kirby disk susceptibility test, all isolates were rated susceptible to minocycline, gentamicin, and polymyxin; 25% were resistant to tetracycline. In agar dilution tests, minocycline was two to four times more potent than gentamicin or polymyxin and eight times more potent than tetracycline. Ampicillin and cephalexin were relatively ineffective. Against lethal infections produced by five strains of
A. calcoaceticus
in mice, minocycline was, in general, more active than gentamicin or polymyxin on a dosage basis and significantly more active on a blood-level basis. Minocycline was significantly more potent than tetracycline on both dosage and blood-level bases against tetracycline-sensitive and -resistant strains. In the last decade there has been an increase in the reported incidence of acinetobacters in a variety of infections. The cultures are susceptible to few antibiotics. Our data show that minocycline could offer an effective alternative to the more toxic drugs for the treatment of these infections. Susceptibility should be determined with minocycline disks.
Multiresistant Plasmids from
Pseudomonas aeruginosa
Highly Resistant to Either or Both Gentamicin and Carbenicillin
Authors: Kontomichalou Polyxeni , Papachristou Efstathia , Angelatou Fevronia
Published: June 2012

High-level resistance to gentamicin and carbenicillin was found in 30 and 10.7%, respectively, of
Pseudomonas aeruginosa
strains, especially in isolates from urine. In 23 out of 25 strains tested, these resistances were R mediated and linked to multiresistant plasmids, carrying genes for resistances to five other aminoglycosides, tobramycin, kanamycin, neomycin, streptomycin, and spectinomycin, and for resistances to chloramphenicol, tetracycline, sulfonamides, and mercury chloride. Carbenicillin resistance was unstable in
Pseudomonas
, and in its presence the multiresistant plasmids had a host range extended to the
Enterobacteriaceae
(group I plasmids). Otherwise they were transferable intragenerically only (group II plasmids). The extended host range plasmids were, as a rule, in fi
−
incompatibility class A–C. Segregants incompatible with both class A–C and P plasmids were detected. The β-lactamase specified by the carbenicillin marker was of the TEM-like type. Multiple linkages of resistance determinants to the aminoglycosides were concomitantly present in most of the plasmids. Results from the bioassay indicated the presence of at least two aminoglycoside-inactivating enzymes.
Genome Sequence of the Halotolerant Bacterium Imtechella halotolerans K1
T
Authors: Kumar Shailesh , Vikram Surendra , Subramanian Srikrishna , Raghava Gajendra Pal Singh , Pinnaka Anil Kumar
Published: June 2012

We report the 3.087-Mb genome sequence of
Imtechella halotolerans
K1
T
, isolated from an estuarine water sample collected from Kochi, Kerala, India. Strain K1 was recently reported as a novel genus of the family
Flavobacteriaceae
.
Elevated liver enzymes, anaemia and osteopaenia in a young woman
Authors: Nielsen Barbara Rubek , Schwarz Peter , Friis Steffen , Gluud Lise Lotte
Published: June 2012

A 23-year-old woman presented with elevated liver enzymes, anaemia and lower limb oedema. Iron-deficiency anaemia due to gynaecological problems was suspected. The patient was treated with iron supplements normalising the blood haemoglobin. Alcohol binge drinking was suspected to be the cause of elevated liver enzymes. After 7 years, the patient presented to our outpatient clinic with non-specific gastrointestinal symptoms. Blood tests revealed low levels of serum s-iron and elevated liver function tests. Abdominal ultrasound was normal. No signs of viral hepatitis or hereditary liver disease were detected. There was a marked elevation of tissue transglutaminase antibodies. A small intestine biopsy confirmed the diagnosis of coeliac disease. A bone density scan showed osteopaenia. Following a gluten-free, lactose-reduced diet, the gastrointestinal symptoms disappeared and s-transaminase activity and s-iron levels normalised.
Strongyloides hyperinfection syndrome following resection of meningioma
Authors: Shelton Clifford Leigh , Smith Timothy , Karabatsou Konstantina , Ajdukiewicz Katherine
Published: June 2012

In this report, we present the case of a patient who developed the strongyloides hyperinfection syndrome 3 weeks after an uneventful resection of a sphenoid wing meningioma. She originally presented with symptoms of raised intracranial pressure and was given dexamethasone before surgery. The pathology, diagnosis and management ofStrongyloides stercoralisare reviewed.
Alopecia: a common paraneoplastic manifestation of cholangiocarcinoma in humans and animals: Figure 1
Authors: Antoniou Efstathios , Paraskeva Panorea , Smyrnis Anastasios , Konstantopoulos Kostas
Published: June 2012

The coincidence of alopecia and a tumour may indicate the paraneoplastic nature of alopecia. Paraneoplastic alopecia is not uncommon in animals, feline paraneoplastic alopecia being the best example known. We present a case of alopecia coinciding with the presentation of a cholangiocarcinoma in a woman. Following surgical resection of the tumour, alopecia resolved spontaneously and it reappeared on local recurrence, 2 years later. As far as pathogenesis is concerned, the coincidence of alopecia and cholangiocarcinoma may indicate the paraneoplastic nature of alopecia as a rare complication of this rare tumour in humans. This also implies that common interspecies mechanism(s) must exist as far as this paraneoplastic complication is concerned.
GENERALIZED COHERENT STATES APPROACH TO DEFORMATION QUANTIZATION
Authors: GHORASHI S. A. A. , ROKNIZADEH R. , HAROUNI M. BAGHERI
Published: June 2012

Generalized (f)-coherent state approach in deformation quantization framework is investigated by using a *-eigenvalue equation. For this purpose we introduce a new Moyal star product called f-star product, so that by using this *f-eigenvalue equation one can obtain exactly the spectrum of a general Hamiltonian of a deformed system. Eventually the method is supported with some examples.
A NONLOCAL VECTOR CALCULUS, NONLOCAL VOLUME-CONSTRAINED PROBLEMS, AND NONLOCAL BALANCE LAWS
Authors: DU QIANG , GUNZBURGER MAX , LEHOUCQ R. B. , ZHOU KUN
Published: June 2012

A vector calculus for nonlocal operators is developed, including the definition of nonlocal divergence, gradient, and curl operators and the derivation of the corresponding adjoint operators. Nonlocal analogs of several theorems and identities of the vector calculus for differential operators are also presented. Relationships between the nonlocal operators and their differential counterparts are established, first in a distributional sense and then in a weak sense by considering weighted integrals of the nonlocal adjoint operators. The operators of the nonlocal calculus are used to define volume-constrained problems that are analogous to elliptic boundary-value problems for differential operators; this is demonstrated via some examples. Another application discussed is the posing of abstract nonlocal balance laws and deriving the corresponding nonlocal field equations; this is demonstrated for heat conduction and the peridynamics model for continuum mechanics.
DEVELOPMENT OF AN IMPROVED INTENSITY MEASURE IN ORDER TO REDUCE THE VARIABILITY IN SEISMIC DEMANDS UNDER NEAR-FAULT GROUND MOTIONS
Authors: YAHYAABADI A. , TEHRANIZADEH M.
Published: June 2012

Intensity measure (IM) which describes the strength of an earthquake record plays an important role in the seismic performance assessment of structures. An improved IM that can reduce the variability in seismic demands helps reducing the number of records necessary to predict the seismic performance with sufficient accuracy. In this study, an improved RMS-based IM is developed based on the results obtained from incremental dynamic analyses of short-to relatively long-period frames under an ensemble of near-fault pulse-like earthquake records. It is observed that the root-mean-square value of pseudo spectral accelerations, (Sa)rms, is generally superior to that of spectral velocities, (Sv)rms, in seismic demand prediction under near-fault records. To compute (Sa)rmsas IM, two appropriate period ranges are suggested for short- and moderated-to relatively long-period frames, respectively. Comparing the efficiency of (Sa)rmswith several advanced IMs shows that (Sa)rmsis more efficient in predicting the inelastic response and collapse capacity of short-period frames. It is also found that intensity measure (Sa)rmsis sufficient with respect to the magnitude and source-to-site distance for all frames of various heights under near-fault ground motions.
RYDBERG EXCITATION OF A BOSE-EINSTEIN CONDENSATE
Authors: BASON M. G. , VITEAU M. , MALOSSI N. , CIAMPINI D. , MORSCH O. , ARIMONDO E.
Published: June 2012

Rydberg excitation of an elongated Bose-Einstein condensate is performed. We show how the dipole-blockade mechanism restricts the number of Rydberg atoms it is possible to excite in such a cloud. Using the super-atom model we then look at the feasibility of observing coherent effects in even stricter geometries, one dimensional optical lattices
THE METHOD OF ELECTRON PARAMAGNETIC RESONANCE FOR QUANTUM ELECTRONIC MATERIALS INVESTIGATION (YAG, YLuAG, YAP, YLuAP, PbGa2S4)
Authors: ASATRYAN HIKE , BARANOV PAVEL
Published: June 2012

The results of EPR investigations of the laser crystals and scintillators are presented, in particular, Y 3 Al 5 O 12: Dy 3+, Y 3 Al 5 O 12: Er 3+, ( Y 1-x Lu x)3 Al 5 O 12: Er 3+, YAlO 3: Er 3+, Ce 3+, Nd 3+ and Tm 3+, Y (1- x ) Lu x AlO 3 : Ce 3+, PbGa 2 S 4 : Dy 3+, Nd 3+ and Ce 3+. EPR signals of Er 3+, Ce 3+, Nd 3+ and Tm 3+ ions in YAlO 3, as well as of Dy 3+, Nd 3+ and Ce 3+ in lead thiogallate single crystals are detected and analyzed for the first time. The main values of g tensors and hyperfine interaction constants for Er 3+, Tm 3+, Nd 3+ and Dy 3+ odd isotopes are determined. In compositionally disordered compounds YLuAG and YLuAP several new paramagnetic Er 3+ and Ce 3+ centers are observed in comparison with YAG and YAP . These centers appear as a result of the changes in the crystal field symmetry and magnitude due to the isomorphic substitution of Lu 3+ for Y 3+ in the yttrium sublattice. The origin of these new paramagnetic centers is established and their formation probability is calculated depending on the content of the additional lutetium impurity. Possible mechanism of the charge compensation for heterovalent substitution of Pb 2+ by RE 3+ in lead thiogallate single crystals is analyzed.
PHOTON-PHOTON INTERACTION IN STRUCTURED QED VACUUM
Authors: HATSAGORTSYAN K. Z. , KRYUCHKYAN G. YU.
Published: June 2012

In spatially structured strong laser fields, quantum electrodynamical vacuum behaves like a nonlinear Kerr medium with modulated third-order susceptibility where new coherent nonlinear effects arise due to modulation. We consider the enhancement of vacuum polarization and magnetization via coherent spatial vacuum effects in the photon-photon interaction process during scattering of a probe laser beam on parallel focused laser beams. Both processes of elastic and inelastic four wave-mixing in structured QED vacuum accompanied with Bragg interference are investigated. The phase-matching conditions and coherent effects in the presence of Bragg grating are analyzed for photon-photon scattering.
MAGNETO-ABSORPTION IN ELLIPSOIDAL QUANTUM DOT
Authors: DVOYAN K.G. , EVOYAN V.V. , KAZARYAN E.M. , NAZMITDINOV R.G. , SARKISYAN H.A.
Published: June 2012

The absorption of light in ellipsoidal quantum dot in the presence of a magnetic field is discussed using perturbation theory. Also the same problem is discussed using the normal modes. Quantum dot absorption coefficient is calculated – as well as threshold frequency of absorption – as a function of applied magnetic field. Theoretical results are compared with experimental data obtained by magneto-luminescence method in In0.53Ga0.47As quantum dot (M. Bayer et al, PRB vol.53, pp. 15810–15814, 1996).
EFFECT OF A SUBWAVELENGTH LAYER ON ALL OPTICAL-DIODE ACTION IN 1D PHOTONIC CRYSTAL
Authors: JAMSHIDI-GHALEH KAZEM , SAFARI ZEINAB
Published: June 2012

In this paper, the effect of a subwavelength layer thickness with positive-refractive index material on all-optical diode action in a one-dimensional photonic crystal structure is investigated. An asymmetric multilayer stack composed of Kerr-type nonlinear and linear dielectric media and a subwavelength layer is considered. Behaviour of the linear transmission defect mode and nonlinear optical bistabilities for normal incidence of wave to 1D photonic crystal structure from left and right sides are studied. It is demonstrated that, with increasing of the subwavelength layer thickness, the linear defect mode shifts to the lower frequencies. Also, the left to right one-way transmission property of the structure is changed for right to left transmission at some subwavelength layer thicknesses. The changes of lower and higher bistability intensities thresholds and difference between left to right and right to left nonlinear transmissions versus subwavelength layer thickness are graphically illustrated. The photonic crystal all-optical diode is one of the important integrated devices, which has potential applications in the field of optical computing, optical interconnection systems and integrated photonic circuits.
CHARGE WAVES IN DOUBLE DOPED PHOTOCHROMIC LITHIUM NIOBATE CRYSTALS
Authors: HOVSEPYAN RUBEN , POGHOSYAN ARMEN , VARDANYAN EDUARD
Published: June 2012

We are presenting the experimental studies of time-space characteristics of photochromic effect in lithium niobate crystals with double doping. The photoinduced autowaves of absorption coefficient changes under the light illumination of limited part of crystal were found. An analytical model is proposed for the explanation of appearance and spreading of charge waves.
STRUCTURAL CHARACTERISTICS OF La2O3 THIN FILM GROWN ON LaB6
Authors: KAFADARYAN Y. A. , PETROSYAN S. I. , BADALYAN G. R. , LAZARYAN V. G. , SHIRINYAN G. H. , AGHAMALYAN N. R. , HOVSEPYAN R. K. , SEMERJIAN H. S. , IGITYAN A. S. , KUZANYAN A. M.
Published: June 2012

Within the framework of hexagonal lanthanum oxide ( h - La 2 O 3) formation, lanthanum hexaboride film on sapphire substrate ( LaB 6/ Al 2 O 3) was oxidized at different temperatures (700-1000 °C) under reduced atmospheric pressure (1·10-2,1.5·10-1Torr) during 30 min. The composition evolution of La 2 O 3/ LaB 6 structure versus annealing temperature has been studied using XRD, FIR reflectivity spectroscopy, SEM and electron probe X-ray microanalysis (EDS). The annealing of the LaB 6 film at T =700 °C under air pressure of 1·10-2 Torr generates thin La 2 O 3 layer which exhibits as inferred from XRD the hexagonal phase. The hydratation of La 2 O 3/ LaB 6/ Al 2 O 3 in distilled water for 30 min and postannealing at 900 °C under air pressure of 1.5·10-1 Torr transform h - La 2 O 3 into hexagonal La ( OH )3 phase accompanied monoclinic LaO ( OH ) and lanthanum oxide carbonate hydrate species.
GENERATION OF DIFFERENCE FREQUENCY RADIATION IN THE FIELD OF FEW-CYCLE LASER PULSE PROPAGATING IN GaAs CRYSTAL WITH PERIODIC AND APERIODIC DOMAIN STRUCTURE
Authors: HOVHANNISYAN D.L. , CHALTIKYAN V.O. , HOVHANNISYAN G.D.
Published: June 2012

We consider process of generation of difference frequency in a GaAs crystal with periodic domain structure during propagation of a few-cycle laser pulse in the crystal in the regime when chromatic dispersion is expressed weakly. Method of lines is used to obtain numerical solution to the system of coupled nonlinear differential equations in partial derivatives describing the evolution of the electric field of a few-cycle laser pulse in GaAs crystal both with periodic and aperiodic domain structure. Time-frequency distribution is obtained, with use of Wigner transformation, for linearly-polarized femtosecond laser pulse and for orthogonally polarized difference-frequency pulse generated via filtration of the orthogonally-polarized pulse at the crystal output.
GENERATION OF THz RADIATION IN NONLINEAR CRYSTAL PARTIALLY FILLING A HOLLOW WAVEGUIDE
Authors: NIKOGHOSYAN A.S.
Published: June 2012

The results of the THz pulse generation via optical rectification of pico- and femtosecond laser pulses in nonlinear crystal are presented. Detection of THz pulses is performed at room temperature by both Schottky diode and ZnTe crystal. The quantum efficiency of energy conversion up to 28% of maximum value is obtained with Schottky diode.
INFLUENCE OF UNEQUAL OSCILLATOR STRENGTHS ON STIMULATED RAMAN ADIABATIC PASSAGE THROUGH BRIGHT STATE
Authors: CHAKHMAKHCHAYN L. , GRIGORYAN G. , LEROY C. , PAHSAYAN-LEROY Y. , GUERIN S. , JAUSLIN H. R.
Published: June 2012

In the present work an analytical and numerical analysis of the b -STIRAP process in a medium with unequal oscillator strengths is performed. It is shown that the length of population transfer can be considerably increased by an appropriate choice of the dipole transitions.
OPTIMIZATION OF FEMTOSECOND PULSE COMPRESSION BY PULSE ASYMMETRY MANAGEMENT
Authors: GRIGORYAN ARMINE , YESAYAN GAREGIN , ZEYTUNYAN ARAM , MOURADIAN LEVON
Published: June 2012

We present results of numerical studies of the phase compensation in the pulse compression process via the shaping of asymmetric pulses at the system input. In this case, an effective pulse compression is achieved, with a ratio corresponding to the pulse spectral broadening in fiber. This opportunity is caused by the fact that self-phase modulation in fiber results in a phase given by the pulse shape.
MULTI-FREQUENCY SECOND HARMONIC GENERATION IN IRREGULAR TWO DIMENSIONAL APERIODIC OPTICAL SUPERLATTICES
Authors: SANG NOUR POUR N. , NEMATI M. , GOALIPOUR M. , REZAEI M. , KHERADMAND R. , KRYUCHKYAN G. YU.
Published: June 2012

We investigate two dimensional nonlinear aperiodic structures leading to multi quasi-phase-matching conditions and multi-frequency second-harmonic generation (SHG) in one chip. For arranging devices close to an experimental situation the intensities of SHG in dependence from frequencies and direction of radiation are studied for irregular structures with random fluctuations of the sizes of each poling domain. Comparing the regular and irregular two dimensional nonlinear aperiodic structures we study the role of imperfection effects of random fluctuations in multi-frequency SHG.
DIRECT INTERBAND LIGHT ABSORPTION IN A SPHERICAL QUANTUM DOT WITH THE MODIFIED PÖSCHEL-TELLER POTENTIAL
Authors: TEVOSYAN H.KH. , HAYRAPETYAN D.B. , DVOYAN K.G. , KAZARYAN E.M.
Published: June 2012

The energy levels and direct interband absorption of light in a spherical quantum dot with a modified Pöschel-Teller confining potential are studied. Analytical expressions for the particle energy spectrum and absorption threshold frequencies in the regime of strong size quantization are obtained. Selection rules for quantum transitions are revealed. Red shift and blue shift of absorption threshold has been observed depending on the values of half-width and depth of confining potential, correspondingly.
Patterning of Spiral Structure on Optical Fiber by Focused-Ion-Beam Etching
Authors: Mekaru Harutaka , Yano Takayuki
Published: June 2012

We produce patterns on minute and curved surfaces of optical fibers, and develop a processing technology for fabricating sensors, antennas, electrical circuits, and other devices on such patterned surfaces by metallization. A three-dimensional processing technology can be used to fabricate a spiral coil on the surface of cylindrical quartz materials, and then the microcoils can also be applied to capillaries of micro-fluid devices, as well as to receiver coils connected to a catheter and an endoscope of nuclear magnetic resonance imaging (MRI) systems used in imaging blood vessels. To create a spiral line pattern with a small linewidth on a full-circumference surface of an optical fiber, focused-ion-beam (FIB) etching was employed. Here, a simple rotation stage comprising a dc motor and an LR3 battery was built. However, during the development of a prototype rotation stage before finalizing a large-scale remodelling of our FIB etching system, a technical problem was encountered where a spiral line could not be processed without running into breaks and notches in the features. It turned out that the problem was caused by axis blur resulting from an eccentric spinning (or wobbling) of the axis of the fiber caused by its unrestrained free end. The problem was solved by installing a rotation guide and an axis suppression device onto the rotation stage. Using this improved rotation stage. we succeeded in the seamless patterning of 1-µm-wide features on the full-circumference surface of a 250-µm-diameter quartz optical fiber (QOF) by FIB etching.
Effect on Critical Dimension Performance for Carbon Contamination of Extreme Ultraviolet Mask Using Coherent Scattering Microscopy and In-situ Contamination System
Authors: Doh Jonggul , Lee Sangsul , Lee Jaewook , Hong Seongchul , Jeong Chang Young , Lee Dong Gun , Kim Seong-Sue , Ahn Jinho
Published: June 2012

The impact of carbon contamination on imaging performance was analyzed using an in-situ accelerated contamination system (ICS) combined with coherent scattering microscopy (CSM) which was installed at 11B extreme ultraviolet lithography (EUVL) beamline of the Pohang Accelerator Laboratory (PAL). The CSM/ICS is composed of CSM for measuring imaging properties and ICS for implementing acceleration of carbon contamination. The mask critical dimension (CD) and reflectivity were compared before and after carbon contamination through accelerated exposure. The reflectivity degradation was measured as 1.3, 2.0, and 2.8% after 1, 2, and 3 h exposure, respectively, due to carbon contamination of 5, 10, and 20 nm as measured by Zygo interferometer. The mask CD change for 88 nm line and space pattern was analyzed using CSM and a CD scanning electron microscope (SEM), and the result shows CD-SEM and CSM give large difference of 3.8 times in mask ΔCD after carbon contamination. This difference confirms the importance of using actinic inspection technique that employs exactly the same imaging condition as exposure tool.
Optimized Multigrid Strategy for Accurate Flare Modeling with Three-Dimensional Mask Effect in Extreme-Ultraviolet Lithography
Authors: Lee Junhwan , Lee Sangheon , Kim Changreol , Kim Yongdae , Kim Sangpyo , Kim Ohyun
Published: June 2012

Extreme-ultraviolet (EUV) lithography has many critical challenges regarding its implementation in the semiconductor industry. One of the main challenges is flare, the unwanted total integrated light scattering at the wafer level, which reduces the critical dimension and imaging performance. Therefore, EUV flare has been intensively studied and has been compensated by a rule-based method for many years. However, there are few results with regard to developing more accurate and feasible flare-modeling techniques to enable us to satisfy the criteria of the sub-22 nm half pitch (HP) technology node and beyond. In this work, we studied an improved flare-modeling technique considering the interaction of scattered EUV light with a three-dimensional EUV mask topography in order to obtain an accurate flare distribution and an optimized multigrid strategy for generating a flare map over the full-field scale. Also, we proposed a flare-modeling technique based on the pedestal model, which we developed using novel effective reflection coefficients in order to achieve sufficient accuracy. Such an approach is thought to be needed instead of the conventional pattern density approach in preparation for upcoming advanced HP technology nodes or for different absorber materials and illumination angles. Lastly, the need for a flare map shift to compensate for the mask defocus error is introduced and some flare evaluations of mask patterns used in the exposure-dose-monitoring technique were performed.
Ion-Beam-Induced Luminescence Analysis as Diagnostic Tool for Microstructure Patterning on Diamond by Proton Beam Writing
Authors: Kada Wataru , Yokoyama Akihito , Koka Masashi , Takano Katsuyoshi , Satoh Takahiro , Kamiya Tomihiro
Published: June 2012

An in situ diagnostics technique for proton beam writing (PBW) on chemical vapor deposition (CVD) diamond was newly established by developing a method of monochromatic ion-beam-induced luminescence (IBIL) analysis. As a compact optic system of IBIL analysis, a couple of optics including a monochromator and a photon counting photomultiplier were installed on the microbeam line of a 3 MV single-ended accelerator. Changes in the crystal structure of single-crystal CVD diamond were continuously monitored by observing the decay of IBIL at a wavelength related to them. Two-dimensional microscopy images of IBIL were also clearly visualized as patterns on diamond in the postprocess of PBW with the same experimental setup. The total fluence of the proton microbeam was well linked to the photon count of IBIL for the fabrication of micrometer-sized carbonized layers in the CVD diamond crystal.
Study on Image Drift Induced by Charging during Observation by Scanning Electron Microscope
Authors: Okai Nobuhiro , Sohda Yasunari
Published: June 2012

The mechanism of image drift in the observation of a boundary between a metal and an insulator by scanning electron microscope (SEM) is clarified by electron-trajectory simulation and experiment. In the region involving a straight boundary between a large-area metal layer and an insulating substrate, the largest image drift is expected to be observed owing to an asymmetric charging on the sample surface. The simulation result shows that a metal–insulator boundary in the SEM image shifts toward the metal part over several seconds, which is induced by a positively charged area outside of the irradiation region in the insulator part. This simulation result is confirmed to qualitatively coincide with the experimental one. In addition, we demonstrate that the direction and magnitude of the image drift can be controlled by changing the charging voltage of the insulating substrate by applying a bias voltage to the anode facing the sample surface.
Defect Inspection Technique Using Surface Plasmon Resonance
Authors: Kashiwagi Hiroyuki , Yoneda Ikuo , Morishita Keiko , Yoshikawa Ryoji , Hirano Takashi , Nakasugi Tetsuro
Published: June 2012

Inspection using surface plasmon resonance is demonstrated by using a Cr photomask with a 200 nm line and space pattern. This inspection makes it possible to detect Cr defects with a side length of 200 nm connected between lines and hole defects disconnected lines. Our experiments indicate that the smallest size of a detectable defect is estimated to be 6.3 nm and the inspection time is less than 10 min by assuming a multibeam system. Moreover, we can apply surface plasmon resonance to the detection of critical dimension error within 10 nm on the photomask. In conclusion, the resolution and throughput for our inspection technique using surface plasmon resonance are higher than those of a conventional mask inspection technique.
Characterization of Fogging and Develop-Loading Effects in Electron-Beam Direct-Writing Technology
Authors: Kon Jun-ichi , Kojima Yoshinori , Takahashi Yasushi , Maruyama Takashi , Sugatani Shinji
Published: June 2012

We investigated long-range critical dimension (CD) error factors, such as fogging and develop loading, to improve CD uniformity in electron-beam direct-writing (EBDW) technology. It was found that the impact of both effects reached 20 mm and the CD of the monitor pattern decreased by no less than 10%. Fogging and develop loading were separated by comparing the newly designed test patterns that were exposed using both EB and a krypton-fluoride excimer laser. We confirmed that the impact of fogging and develop loading by arranging dummy patterns with a density of 40% was estimated to be +8.9 and -18.9% in the CD, respectively. Based on success in separating each effect, fogging and develop loading were decreased by applying an antistatic agent and multipuddle development, respectively.
In situ Dissolution Analysis of Ultrathin Extreme Ultraviolet Resists
Authors: Santillan Julius J. , Itani Toshiro
Published: June 2012

With extreme ultraviolet (EUV) resists reaching resolution capabilities beyond the 20 nm half-pitch line and space patterns, a trend has emerged in applying ultrathin resists (film thickness less than 60 nm) to compensate for possible issues in resolution-limiting pattern collapse and line width roughness, among other aspects. Thus, a clear understanding of the pattern mechanisms of resists at these extreme conditions is necessary. This paper focuses on the pattern formation characteristics of various EUV resist platforms for ultrathin films during dissolution by using in situ high-speed atomic force microscopy in liquid. As a result, it was observed that, regardless of the resist platform, there is a decrease in the size of the “dissolution clusters” at ultrathin conditions. Such fundamental information on ultrathin resist films may provide possible pointers to further extend the potential of EUV resists for achieving higher resolution limits and minimal line width roughness.
Epitaxy of Graphene on 3C-SiC(111) Thin Films on Microfabricated Si(111) Substrates
Authors: Ide Takayuki , Kawai Yusuke , Handa Hiroyuki , Fukidome Hirokazu , Kotsugi Masato , Ohkochi Takuo , Enta Yoshiharu , Kinoshita Toyohiko , Yoshigoe Akitaka , Teraoka Yuden , Suemitsu Maki
Published: June 2012

The epitaxy of graphene on 3C-SiC(111) formed on microfabricated Si(111) has been demonstrated. Through observations by optical microscopy, micro-Raman spectroscopy, low-energy electron diffraction, and photoelectron spectroscopy, it has been confirmed that the epitaxial graphene is Bernal-stacked with a buffer layer present between graphene and the 3C-SiC film, which can lead to the opening of the band gap necessary for logic operations. The quality of graphene is improved by the shrinkage of the pattern. These results indicate that graphene on silicon using the microfabricated substrate is a promising material for the realization of graphene-based devices.
Carrier Transport Properties of the Field Effect Transistors with Graphene Channel Prepared by Chemical Vapor Deposition
Authors: Negishi Ryota , Ohno Yasuhide , Maehashi Kenzo , Matsumoto Kazuhiko , Kobayashi Yoshihiro
Published: June 2012

We investigate the carrier transport properties of multilayer graphene with a turbostratic structure grown by chemical vapor deposition (CVD). The observed sheet resistivity of field effect transistors using the grown multilayer graphene (GG-FETs) with a turbostratic structure as a channel is almost constant at any temperature. The feature is virtually identical to that of FET using monolayer graphene rather than to that of FET using mechanically exfoliated multilayer graphene with well-ordered stacking. This indicates that the electronic band of the grown multilayer graphene with a turbostratic structure has a linear dispersion around the Dirac point similarity to that of a monolayer graphene. The mobility of the GG-FETs is low (300–400 cm2 V-1 s-1) in comparison with that of the FETs using mechanically exfoliated graphene. From structural analysis using Raman spectroscopy, we find that the low carrier mobility can be explained by the existence of a charged impurity at the grown graphene layers.
Immunosensors Based on Graphene Field-Effect Transistors Fabricated Using Antigen-Binding Fragment
Authors: Okamoto Shogo , Ohno Yasuhide , Maehashi Kenzo , Inoue Koichi , Matsumoto Kazuhiko
Published: June 2012

To realize the antigen-antibody reaction for specific protein sensing using graphene field-effect transistors (G-FETs), the antigen-binding fragment (Fab), which is a component of conventional antibodies, was functionalized onto the graphene channel surface. Since the height of the Fab is approximately 3 nm, the antigen-antibody reaction is expected to occur inside the electrical double layer in the buffer solution. After functionalization of Fab onto the G-FET, the transfer characteristics shifted in the positive gate-voltage direction, indicating that the Fab was successfully modified onto the graphene surface. Then, the drain current changed after injecting the target proteins, and the dissociation constant was estimated to be 2.3 nM from the concentration dependence. These results indicate that the Fab-modified G-FETs have high potentials as highly sensitive biological sensors fabricated on the basis of the antigen-antibody reaction.
Carbon Nanotube-Based Floating Gate Memories with High-k Dielectrics
Authors: Fujii Yusuke , Ohori Takahiro , Ohno Yasuhide , Maehashi Kenzo , Inoue Koichi , Matsumoto Kazuhiko
Published: June 2012

Carbon nanotube (CNT)-based floating gate memories with high-k dielectrics were fabricated for low-power-consumption devices owing to the increase in the electric field intensity in the tunneling layer of memory devices. The memory with a high-k dielectric consisting of an Al2O3 layer achieved a larger hysteresis than the memory with a SiO2 layer. The results were well explained by simple electric field calculations using a cylindrical capacitor model. Furthermore, memory operation at a lower pulse voltage of 2 V or a shorter pulse width of 0.01 s was demonstrated on the basis of the memory with the Al2O3 layer. The results indicate that CNT-based floating gate memories with high-k dielectrics are promising candidates for low-power-consumption memories.
Direct Synthesis of Graphene on SiO2 Substrates by Transfer-Free Processes
Authors: Gumi Kenta , Ohno Yasuhide , Maehashi Kenzo , Inoue Koichi , Matsumoto Kazuhiko
Published: June 2012

We have demonstrated the direct the synthesis of graphene on SiO2 substrates by transfer-free processes. An amorphous layer was sandwiched between a Ni layer and a SiO2/Si substrate, and then the sample was annealed under H2 and Ar ambient. The measurements by scanning electron microscopy and Raman spectroscopy reveal that Ni islands were formed and that the 2D band was clearly observed at the region between Ni islands. From the intensity ratio of the G band to the 2D band, multilayer graphene was concluded to have been synthesized owing to the retraction of the Ni layer during annealing of the sample.
Configuration Dependency of Attached Epoxy Groups on Graphene Oxide Reduction: A Molecular Dynamics Simulation
Authors: Yun Kyung-Han , Hwang Yubin , Lee Minho , Choi Heechae , Yoo Dong Su , Lee Eung-Kwan , Cho Sung Beom , Chung Yong-Chae
Published: June 2012

The atomic behavior of epoxy groups on a graphene oxide sheet was observed during high thermal heat annealing using a reactive force-field based on molecular dynamics simulations. We found the oxygen-containing functional groups interplay with each other and desorbed from the graphene oxide sheet by a form of O2 gas if they were initially in close distance. Through comparing reduction results of graphene oxide with different densities of the nearest neighboring epoxy pairs, we confirmed that the amount of released O2 gas has a clear tendency to increase with a higher density of epoxy pairs in close distance on a graphene oxide sheet.
One-Step Liquid-Phase Synthesis of Carbon Nanotubes: Effects of Substrate Materials on Morphology of Carbon Nanotubes
Authors: Yamagiwa Kiyofumi , Ayato Yusuke , Kuwano Jun
Published: June 2012

Effects of substrate materials and shapes have been investigated in the one-step liquid-phase (OS-LP) synthesis of carbon nanotubes (CNTs). Similar highly aligned multi-walled CNT (MWCNT) arrays (HACNTAs) with a height (ha) of ∼30 µm were synthesized on the substrates of commercially available stainless steel and Inconel®alloy by a resistance heating method in methanol containing cobaltocene, whereas aligned MWCNT arrays (ha≈10 µm) with slightly poor alignment were formed on the titanium substrate, compared with those of the former two. On the other hand, very short, non-aligned MWCNTs with a length of ∼1 µm were deposited on a silicon substrate. The different morphologies depending on the substrate materials are related with interaction between the pyrolytically-generated Co atoms and the surface oxide layers of the substrates. In addition, we have for the first time demonstrated that the OS-LP synthesis is suitable for CNT-coating onto intricately-shaped substrates like stainless steel mesh.
Process Optimization for Synthesis of High-Quality Graphene Films by Low-Pressure Chemical Vapor Deposition
Authors: Lee Dongheon , Lee Kihwan , Jeong Saebyuk , Lee Juhyun , Choi Bosik , Lee Jeongsoo , Kim Ohyun
Published: June 2012

Low-pressure chemical vapor deposition (LPCVD) is a simple and useful method for the large-area synthesis of graphene films. Here, we have investigated how to adjust and optimize process conditions for the synthesis of single-layer graphene films by LPCVD. Through our experimental procedure, uniform and high-quality graphene films could be grown on Cu foil at 1000 °C for 20 min with an H2flow rate of 20 sccm, CH4flow rate of 40 sccm, total pressure of 1.7 Torr, and a fast cooling rate (>10 °C/s). In a Raman spectrum measured from synthesized graphene film, we found that the full width at half-maximum (FWHM) of a symmetric 2D peak centered at 2682.5 cm-1was 34 cm-1and the 2D-to-G intensity ratio was 1.35.
Low-Temperature Synthesis of Single-Walled Carbon Nanotubes in a High Vacuum Using Pt Catalyst in Alcohol Gas Source Method
Authors: Fukuoka Naoya , Mizutani Yoshihiro , Naritsuka Shigeya , Maruyama Takahiro , Iijima Sumio
Published: June 2012

The growth of single-walled carbon nanotubes (SWCNTs) was carried out on SiO2/Si substrates with Pt catalysts between 500 and 700 °C under various ethanol pressures using an alcohol gas source method in a high vacuum and the grown SWCNTs were characterized by scanning electron microscopy (SEM) and Raman spectroscopy. It was found that, irrespective of the growth temperature, the optimal ethanol pressures were 1×10-3–1×10-4 Pa, which were much smaller than those used in the SWCNT growth with Co catalysts. SEM observations showed that the yield of SWCNTs grown with a Pt catalyst under 1×10-3 Pa at 700 °C was similar to that with a Co catalyst under the optimal growth condition, even though the ethanol pressure was fairly lower in the growth with Pt. By optimizing the growth pressure, SWCNTs could be grown even at 500 °C by using a Pt catalyst.
Evaluation of Graphene Thin Films by Surface Plasmon Resonance
Authors: Murasaki Kohei , Anno Yuki , Akita Seiji , Arie Takayuki
Published: June 2012

We have proposed the application of the surface plasmon resonance method to the measurement of the optical response of graphene thin films. A surface plasmon is a coherent electron oscillation that is excited at the interface between two materials when p-polarized light is incident. We revealed that the excitation angle shifts by about 0.1° in the case of monolayer graphene compared with the bare Au surface as determined by calculation. We also identified angle shifts of the excitation conditions for surface plasmon experimentally when graphene thin films fabricated by filtration exist on the Au surface, corresponding to 5–8 layers of graphene, as determined by the calculation.
Temperature Dependent Resistance of Multi-Wall Carbon Nanotube
Authors: Kawabe Eiji , Itaya Shotaro , Hirahara Kaori , Nakayama Yoshikazu
Published: June 2012

This study investigates electron transport properties of a Joule heated multi-wall carbon nanotube at temperatures as high as about 2100 K. Results show that the electrical resistance is temperature-dependent. The temperature dependence of the resistance is inferred to originate from the temperature-dependent intrashell resistance and intershell conductance. The resistance variation was analyzed using a resistive transmission line model. Results well reproduced those obtained using a double shell conduction model where the electrons transport in the outermost shell and the second inner shell.