bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of Point Defects in the Physical Properties of Fluorite Oxides
Authors: Duncan Keith L. , Wang Yanli , Bishop Sean R. , Ebrahimi Fereshteh , Wachsman Eric D.
Published: September 2006

For the first time, explicit, analytical expressions have been derived for the dependence of electrical conductivity, chemical expansion, and elastic modulus on defect concentration and oxygen partial pressure using a consistent approach. The models have been validated with experimental data for Ce0.9Gd0.1O1.95−δ (GDC) with consistently good fits. In developing the model, expressions were first derived for the functional dependence of defect concentration on the oxygen partial pressure (PO2) for n‐type fluorite oxides. Expressions for the chemical expansion, elastic modulus, and electrical conductivity as functions of defect concentration are then derived and verified with experimental data.
Praseodymium‐Doped Photo‐Luminescent Strontium Indate Nanoparticles by Ultrasonic Spray Pyrolysis
Authors: Lin S.E. , Borgohain K. , Wei W. C. J.
Published: September 2006

Submicrometer spherical particles of praseodymium (Pr)‐doped strontium indate were synthesized by spray pyrolysis using ultrasonic nebulization. The morphology, crystalline structure, particle size, and size distribution were studied by X‐ray diffraction, scanning, and transmission electron microscopies. The spherical agglomerates were found to be made up of very small nanocrystallites. Upon excitation by UV radiation, sharp luminescence emission bands due to Pr were observed in the blue, green, and red regions in these Pr‐doped samples.
Electron Carrier Generation in a Refractory Oxide 12CaO·7Al2O3 by Heating in Reducing Atmosphere: Conversion from an Insulator to a Persistent Conductor
Authors: Kim Sung‐Wng , Hayashi Katsuro , Hirano Masahiro , Hosono Hideo , Tanaka Isao
Published: September 2006

Electron carriers were generated in refractory oxide 12CaO·7Al2O3 (C12A7) through a thermal treatment in a reducing CO/CO2 atmosphere, and the reduction process was thermodynamically analyzed. Electrical‐conductive C12A7, which had an electron concentration of ∼8 × 1019 cm−3 and an electrical conductivity of ∼4 S/cm at 300 K, was obtained by extracting free O2− ions in sub‐nanometer‐sized cages in the C12A7 lattice and leaving electrons behind. The enthalpy for this substitutive reaction is +425 kJ/mol, suggesting that stoichiometric C12A7 is more stable in air than the C12A7 electride.
Effect of Carbonation on Alkali‐Activated Slag Paste
Authors: Palacios M. , Puertas F.
Published: September 2006

Carbonation on waterglass‐ and NaOH‐activated slag pastes was analyzed and compared with carbonation in Portland cement pastes to determine possible differences. Thermogravimetry‐differential thermal analysis (TG/DTA), Fourier‐transform infrared spectrometry, and nuclear magnetic resonance were used to determine the effects on the main reaction products. According to the TG/DTA results, carbonate precipitation following carbonation is much more intense in Portland cement pastes than in alkali‐activated slag pastes. This may be attributed to the fact that in Portland cement paste both the portlandite and the C–S–H gel can be carbonated, whereas in alkali‐activated slag pastes, only the C–S–H gel is carbonated directly. In both systems, carbonation leads to the formation of CaCO3, Si‐rich C–S–H gel, silica gel, and alumina. The carbonation of waterglass‐activated slag pastes is not altered by the presence of either of the organic additives used in the study.
Direct Laser Sintering of Al2O3–SiO2 Dental Ceramic Components by Layer‐Wise Slurry Deposition
Authors: Gahler André , Heinrich Jürgen G. , Günster Jens
Published: September 2006

This publication presents a solid freeform fabrication technique for ceramics in the alumina–silica system by layering binder‐free, high‐loaded ceramic slurries, followed by selective laser sintering. The low melting silica phase and the reaction sintering between silica and alumina favor the rapid prototyping of pure ceramic parts. On the basis of electroacoustic and viscosity measurements, stable slurries from Al2O3/SiO2 powder mixtures and water with a high fluidity have been prepared for the layer deposition with a doctor blade like in tape casting. Layers with a thickness of about 100 μm were processed. It was found in laser parameter studies that ceramic parts can only be obtained using special alumina contents and laser parameters. But the biphasic approach may allow greater flexibility in the processing regime than is afforded by the use of just one material. The microstructure of these parts depends mainly on the temperature gradient induced by the laser absorption and thermal conduction. The wet shaping facilitates laser‐sintered parts with a relatively high density, which could be increased by a thermal post‐treatment.
Mechano‐Synthesis of Lead–Magnesium–Niobate Ceramics
Authors: Kuscer Danjela , Holc Janez , Kosec Marija , Meden Anton
Published: September 2006

The synthesis of Pb(Mg1/3Nb2/3)O3 (PMN) with high‐energy milling was studied by X‐ray powder diffraction (XRD) using the Rietveld‐refinement method. The results are discussed in terms of the qualitative and quantitative composition of the crystalline and amorphous phases as a function of milling time. The mechano‐synthesis of PbO, Nb2O5, and MgO leads to the formation of perovskite PMN. In the initial stage of milling, particle size reduction and a high degree of amorphization were observed, together with the simultaneous formation of perovskite and pyrochlore‐type structures. A mechanism for the formation of PMN by the mechano‐synthesis route is proposed.
Effect of Drying and Dewatering on Yttria Precursors with Transient Morphology
Authors: Mouzon Johanne , Odén Magnus , Tillement Olivier , Jorand Yves
Published: September 2006

The influence of drying and dewatering of a yttrium hydroxynitrate precursor with transient morphology was investigated. The ability of this precursor to form soft agglomerated nanoparticles after calcination is dependent on the dewatering method. Freeze drying leads to finer particles than other dewatering methods that involve removal of the solvent from its liquid state. As water is directly removed by sublimation during freeze drying, this method inhibits the formation of solid bridges between hydroxynitrate platelets. These bridges, which form with the other dewatering methods, destabilize the spheroidization process of the platelets during subsequent firing at high temperatures.
Microwave Dielectric Properties of 5Li2O–0.583Nb2O5–3.248TiO2 Ceramics with V2O5
Authors: Zeng Qun , Li Wei , Shi Jian‐lin , Guo Jing‐kun
Published: September 2006

The effects of V2O5 addition on the sintering behavior, microstructure, and the microwave dielectric properties of 5Li2O–0.583Nb2O5–3.248TiO2 (LNT) ceramics have been investigated. With addition of low‐level doping of V2O5 (≤2 wt%), the sintering temperature of the LNT ceramics could be lowered down to around 920°C due to the liquid phase effect. A secondary phase was observed at the level of 2 wt% V2O5 addition. The addition of V2O5 does not induce much degradation in the microwave dielectric properties but lowers the τf value to near zero. Typically, the excellent microwave dielectric properties of ɛr=21.5, Q×f=32 938 GHz, and τf=6.1 ppm/°C could be obtained for the 1 wt% V2O5‐doped sample sintered at 920°C, which is promising for application of the multilayer microwave devices using Ag as an internal electrode.
Report of an angiosarcoma mimic: cutaneous aneurysmal fibrous histiocytoma
Authors: VENKATARAMAN GIRISH , HAMMADEH RASHEED
Published: September 2006

Aneurysmal fibrous histiocytoma is an unusual variant of the spectrum of fibrous histiocytomas with the peculiar morphologic appearance of a benign aneurysmal vasoformative process that ultimately culminates in multiple microhemorrhages within the tumor. It looks strikingly different from the usual cutaneous lesions encountered in clinical dermatology practice. A single report of a cutaneous aneurysmal fibrous histiocytoma in the skin of the back of a 60‐year‐old male is described with emphasis on the immunostaining pattern and review of the literature. There is a significant potential for confusion of this lesion with other cutaneous lesions, clinically as well as pathologically. In our case, the patient presented with a lesion that clinically resembled a hemangioma, was pathologically interpreted initially to be an angiosarcoma, and finally, the revised pathology was interpreted as an aneurysmal variant of a fibrous histiocytoma. Caution is warranted to avoid misinterpretation of cutaneous fibrohistiocytic tumors.
Hemophagocytic macrophages constitute a major compartment of heme oxygenase expression in sepsis
Authors: Schaer Dominik J. , Schaer Christian A. , Schoedon Gabriele , Imhof Alexander , Kurrer Michael O.
Published: September 2006

Abstract:  Objectives: Uncontrolled macrophage activation with hemophagocytosis is a distinctive feature of hemophagocytic syndromes (HPS). We examined whether lympho‐histiocytic infiltration of the bone marrow and liver, as well as hemo‐/erythrophagocytosis also occurs during sepsis and whether this process could account for the increased production of anti‐inflammatory heme‐oxygenase (HO‐1) products observed during sepsis. Methods: Hemophagocytosis and expression of CD163, HO‐1, ferritin as well as CD8 and granzyme‐B were examined in post‐mortem bone marrow samples from 28 patients with sepsis and from eight control patients. Results: Comparison of samples from non‐septic patients with samples from patients with fatal sepsis revealed that the latter group displayed dense lympho‐histiocytic bone marrow infiltration with CD163+/HO‐1+/ferritin+ macrophages as well as with CD8+ and granzyme‐B+ T‐cells. Hemophagocytosis with prominent phagocytosis of erythroid cells was readily apparent in septic patients, implying that this process is a likely stimulus for the up‐regulation of macrophage HO‐1 expression. Conclusions: Lympho‐histiocytic activation with hemophagocytosis is a shared pathophysiologic mechanism in HPS and sepsis. Furthermore, the association of hemophagocytosis with an increase in HO‐1 expression may indicate a novel role for this apparently futile process as a negative regulator of inflammation.
Reduction of a biochemical model with preservation of its basic dynamic properties
Authors: Danø Sune , Madsen Mads F. , Schmidt Henning , Cedersund Gunnar
Published: September 2006

The complexity of full‐scale metabolic models is a major obstacle for their effective use in computational systems biology. The aim of model reduction is to circumvent this problem by eliminating parts of a model that are unimportant for the properties of interest. The choice of reduction method is influenced both by the type of model complexity and by the objective of the reduction; therefore, no single method is superior in all cases. In this study we present a comparative study of two different methods applied to a 20D model of yeast glycolytic oscillations. Our objective is to obtain biochemically meaningful reduced models, which reproduce the dynamic properties of the 20D model. The first method uses lumping and subsequent constrained parameter optimization. The second method is a novel approach that eliminates variables not essential for the dynamics. The applications of the two methods result in models of eight (lumping), six (elimination) and three (lumping followed by elimination) dimensions. All models have similar dynamic properties and pin‐point the same interactions as being crucial for generation of the oscillations. The advantage of the novel method is that it is algorithmic, and does not require input in the form of biochemical knowledge. The lumping approach, however, is better at preserving biochemical properties, as we show through extensive analyses of the models.
The Visiting Specialist Model of Rural Health Care Delivery: A Survey in Massachusetts
Authors: Drew Jacob , Cashman Suzanne B. , Savageau Judith A. , Stenger Joseph
Published: September 2006

ABSTRACT: 
Context: Hospitals in rural communities may seek to increase specialty care access by establishing clinics staffed by visiting specialists. Purpose: To examine the visiting specialist care delivery model in Massachusetts, including reasons specialists develop secondary rural practices and distances they travel, as well as their degree of satisfaction and intention to continue the visiting arrangement. Methods: Visiting specialists at 11 rural hospitals were asked to complete a mailed survey. Findings: Visiting specialists were almost evenly split between the medical (54%) and surgical (46%) specialties, with ophthalmology, nephrology, and obstetrics/gynecology the most common specialties reported. A higher proportion of visiting specialists than specialists statewide were male (P = .001). Supplementing their patient base and income were the most important reasons visiting specialists reported for having initiated an ancillary clinic. There was a significant negative correlation between a hospital’s number of staffed beds and the total number of visiting specialists it hosted (r =−0.573, P = .032); study hospitals ranged in bed size from 15 to 129. Conclusions: The goal of matching supply of health care services with demand has been elusive. Visiting specialist clinics may represent an element of a market structure that expands access to needed services in rural areas. They should be included in any enumeration of physician availability.
Nonfatal All‐Terrain Vehicle–Related Injuries to Youths Living on Farms in the United States, 2001
Authors: Goldcamp E. Michael , Myers John , Hendricks Kitty , Layne Larry , Helmkamp Jim
Published: September 2006

ABSTRACT: 
Context: Use of all‐terrain vehicles (ATVs) in agriculture appears to be growing. Purpose: To provide estimates of ATV ownership and exposure on US farms and an overview of injuries to youths as a result of ATV use on the farm in 2001. Methods: Analysis of the National Institute for Occupational Safety and Health and US Department of Agriculture 2001 Childhood Agricultural Injury Survey. These data, collected via telephone surveys, provide information on nonfatal injuries that occurred to youths younger than 20 years living on US farms during 2001. The injuries included both occupational and nonoccupational incidents. Findings: Of an estimated 1.1 million youths living on farms, 36% had operated an ATV in 2001. Youths younger than 16 years were more likely to have operated an ATV than a tractor on these farms. An estimated 2,246 nonfatal ATV‐related injuries occurred to youths younger than 20 years on US farms during 2001. The majority of these ATV injuries (1,668, 74%) occurred to youths identified as members of the household. Males accounted for 1,145 (69%) of the ATV injuries to household youths. The majority of the injuries were to youths aged 10‐15 years (1,170, 70%). Most ATV injuries were the result of recreational activities (970, 58%). In addition, many of these injury events involved youths riding without helmets and using ATVs that were larger than the recommended size for their age.
Pharmacist Staffing, Technology Use, and Implementation of Medication Safety Practices in Rural Hospitals
Authors: Casey Michelle M. , Moscovice Ira S. , Davidson Gestur
Published: September 2006

ABSTRACT: 
Context: Medication safety is clearly an important quality issue for rural hospitals. However, rural hospitals face special challenges implementing medication safety practices in terms of their staffing and financial and technical resources. Purpose: This study assessed the capacity of small rural hospitals to implement medication safety practices, with particular focus on pharmacist staffing and the availability of technology. Methods: A telephone survey of a national random sample of small rural hospitals was conducted from March to May 2005 (N = 387 hospitals, 94.6% response rate). Survey respondents included pharmacists (89%) and directors of nursing (11%). Multivariate analyses examined the relationships between hospital organizational and financial variables and (1) the amount of pharmacist staffing; (2) use of pharmacy computers for medication safety activities; and (3) implementation of medication safety practices. Findings: Many small rural hospitals have limited hours of on‐site pharmacist coverage. Almost one quarter of hospitals either do not have a pharmacy computer or are not using it for clinical purposes. Half of the hospitals have implemented 4 key medication safety practices. Level of pharmacist staffing, use of technology, and implementation of medication safety practices are significantly related to hospital financial status and accreditation. Conclusions: Implementation of protocols related to medication use and key medication safety practices are areas where small rural hospitals could improve. The study results support a continuation of Medicare cost‐based reimbursement policies to help ensure financial stability and support quality and patient safety activities in small rural hospitals.
Comparison of Rural and Urban Residents’ Implicit and Explicit Attitudes Related to Seeking Medical Care
Authors: Harju Beverly L. , Wuensch Karl L. , Kuhl Emily A. , Cross Natalie J.
Published: September 2006

ABSTRACT: 
Context: The decision whether or not to consult a physician draws from a variety of attitudes within an individual’s health schema. While rural Americans are in greater need of health care, many of them have fewer external resources than urbanites available to them. Purpose: The objective of this study was to elicit implicit and explicit attitudes related to seeking medical treatment for a condition described as fairly serious. Participants were asked to rate how often they comply with treatment regimens and practice good health habits. Methods: The sample of rural (N = 586) and urban (N = 433) North Carolina residents was derived based on random‐digit dialing. Multiple regression analyses were performed to investigate how attitudes associated with perceived compliance and health behaviors. Findings: While rural and urban residents offered very similar responses, the associations between attitudes and behaviors were different. One healthy and 2 unhealthy schema patterns emerged. First, fear of hospitals was associated with effective compliance for rural residents and good health habits for urbanites. Second, affordability concerns were ascribed to rural community residents but seemed to reflect personally relevant implicit attitudes since they were associated with poor health adherence and habits for rural residents. Third, mistrust of doctors predicted low adherence for both groups and was also associated with poorer health habits for urbanites. With inconsistencies among implicit and explicit attitudes and behaviors, some residents seemed to be ambivalent about seeking health care.
Clinical presentation and management of moxidectin toxicity in two dogs
Authors: Snowden N. J. , Helyar C. V. , Platt S. R. , Penderis J.
Published: September 2006

Moxidectin is a macrocyclic lactone related to ivermectin used in horses and dogs for endoparasite treatment and prophylaxis. The clinical and neurological presentation of moxidectin toxicity in two dogs following inadvertent poisoning with a moxidectin‐containing equine de‐worming medication is reported here. In both the dogs, the predominant clinical signs were generalised tremors and ataxia. Moxidectin exerts its neurotoxic effects in mammals by potentiating the effect of γ‐aminobutyric acid and, consistent with this, both the dogs demonstrated a poor response to treatment with diazepam. It would be more appropriate to avoid γ‐aminobutyric acid agonists, such as benzodiazepines and barbiturates, in dogs with moxidectin toxicity and consider using anaesthetic agents with a different mode of action, such as propofol. The prognosis in dogs accidentally exposed to moxidectin‐containing equine de‐worming medication appears to be excellent if the cause of the neurotoxicity is correctly identified and the case is appropriately managed.
Doppler shift viewed as a result of variable delay
Authors: Myers Glen A.
Published: September 2006

Doppler is presented as the consequence of variable delay. The general Doppler shift equation is derived in a way that can be applied to any waveform having ‘‘frequency.’’ The waveform need not be sinusoidal. Comments on laboratory methods of creating Doppler using clocked storage elements are included. The results of an experiment are stated.
Superconducting applications
Authors: Wienke B. R. , Buzbee B. L.
Published: September 2006

A number of uses for present day supercomputers are considered. Among the applications disscused are aircraft design, quantum chromodynamics, particle transport, hydrodynamics, and plasma plysics. (AIP)
Using the graphing calculator—in collision problems
Authors: Stowe Lawrence G.
Published: September 2006

Notice to the keyboarder: Please delete this line.
What is a photon?
Authors: Marburger John H.
Published: September 2006

The words ‘‘table’’ and ‘‘light,’’ as we ordinarily use them, are what we might call ‘‘classical words.’’ They refer to things that we imagine to have an objective reality between events of observation. We know from our experience with quantum mechanics that this imagined reality is only an approximation, usually a very good one. The word ‘‘photon,’’ however, is a ‘‘quantum word’’ that describes a phenomenon for which no classical work is adequate.
Genomic Evolution of Hox Gene Clusters
Authors: Lemons Derek , McGinnis William
Published: September 2006

The family of Hox genes, which number 4 to 48 per genome depending on the animal, control morphologies on the main body axis of nearly all metazoans. The conventional wisdom is that Hox genes are arranged in chromosomal clusters in colinear order with their expression patterns on the body axis. However, recent evidence has shown that Hox gene clusters are fragmented, reduced, or expanded in many animals—findings that correlate with interesting morphological changes in evolution. Hox gene clusters also contain many noncoding RNAs, such as intergenic regulatory transcripts and evolutionarily conserved microRNAs, some of whose developmental functions have recently been explored.
From Magnetic Mines to DNA and Consciousness
Authors: Orgel Leslie
Published: September 2006

Francis Crick
. Discoverer of the Genetic Code.
By Matt Ridley
. Atlas Books (HarperCollins), New York, 2006. 223 pp. $19.95, C$25.95. ISBN 0-06-082333-X. Eminent Lives.

In this latest addition to the "Eminent Lives" series, the author offers nonspecialists a concise account of Crick's life and multi-disciplinary science.
Intrinsic Macrolide Resistance in Rapidly Growing Mycobacteria
Authors: Nash Kevin A. , Andini Nadya , Zhang Yansheng , Brown-Elliott Barbara A. , Wallace Richard J.
Published: September 2006

This study reports the discovery of
erm
genes in seven species of rapidly growing mycobacteria (RGM):
Mycobacterium boenickei
,
M. goodii
,
M. houstonense
,
M. mageritense
,
M. neworleansense
,
M. porcinum
, and
M. wolinskyi
. This study further substantiates the role of
erm
genes in intrinsic macrolide resistance in RGM.
MASSIVE PARTICLES' HAWKING RADIATION VIA TUNNELING FROM THE G.H. DILATON BLACK HOLE
Authors: HU YAPENG , ZHANG JINGYI , ZHAO ZHENG
Published: September 2006

In the past, Hawking radiation was viewed as a tunneling process and the barrier was just created by the outgoing particle itself. In this paper, Parikh's recent work is extended to the case of massive particles' tunneling. We investigate the behavior of the tunneling massive particles from a particular black hole solution — G.H. Dilaton black hole which is obtained from the string theory, and calculate the emission rate at which massive particles tunnel across the event horizon. We obtain that the result is also consistent with an underlying unitary theory. Furthermore, the result takes the same functional form as that of massless particles.
THEORETICAL STUDIES OF ONE- AND TWO-PHOTON ABSORPTION PROPERTIES FOR SYMMETRIC MOLECULES BASED ON BIS(STILBENE)DIETHYLENE
Authors: ZHOU SHU-LAN , ZHAO XIAN , SUN XUE-QIN , CHENG XIU-FENG
Published: September 2006

In order to investigate the substituting effects on the two-photon absorption (TPA) cross-section and the position of the TPA peak, the one- and two-photon absorption properties of a series of symmetric molecules with bis(stilbene)diethylene π-conjugated bridge have been studied using ZINDO-SOS method. The transition moments from the ground state to the lowest excited state (M0k) and from the lowest excited state to the TPA final state (Mkn), together with the detuning energy ΔE = E0k - Ekn/2, were calculated using the INDO1 method included in the ZINDO program. The results indicate that bis-donor and bis-acceptor substitutions mainly affect the transition dipole moments M0k and Mkn, and that donor or acceptor side groups have a strong influence on the detuning energy. Meanwhile, it was found that the molecules with the bis-donor structure possess enhanced TPA cross sections, and the molecules with cyano or methoxy side groups have a large red-shift with respect to molecules without side groups.
STRUCTURES AND ENERGETICS OF PORPHYRIN-FULLERENE SUPRAMOLECULAR COMPLEXES
Authors: KANG CONGMIN , LIN ZHENYANG
Published: September 2006

In this paper, the structures and energetics of porphyrin-fullerene supramolecular complexes have been investigated theoretically via molecular mechanics calculations on complexes having different porphyrins. The results of the calculations allow us to delineate the effect of the substituents on the porphyrin ring on the porphyrin-fullerene interaction energies. The calculations also allow us to understand how the van der Waals force affects the structures of the 2:1, 2:2, and 3:1 supramolecular complexes.
X-ray Topographic Studies on the Lüders Band Propagation and the Dislocation Motion in Copper Whisker Crystals
Authors: Nittono Osamu
Published: September 2006

Dislocations in plastically deformed blade-like [110] copper whisker crystals with thickness of 20 to 70 µ are studied by means of X-ray transmission topograpay. Topographs are taken under the application of tensile stress. Dislocations with a semi-circular shape are always observed to spread over a long distance more than 100 µ in front of the Lüders band, and they are shown to become cross-slipped and double cross-slipped dislocations. The Lüders band can propagate according to the double cross slip mechanism. This may be true for the cases of [001] and [111] copper whisker crystals. Concaves on the crystal edge are the effective sites for dislocation sources. The dislocation motion is not steady and the dislocation pinning due to impurities may be responsible for the irregular dislocation motion. Results obtained indicate that the coarse copper whisker crystals are useful for the studies on the plastic deformation.
Cause of the High Pesistance Region at Vapour Epitaxial GaAs Layer-Substrate Interface
Authors: Saito Takeshi , Hasegawa Fumio
Published: September 2006

A trial is made to clarify the cause of the high resistance region at the interface between the GaAs substrate and the epitaxial layer grown by the Ga/AsCl3/H2 process. Layers were grown under conditions (a) the temperature of the substrate is changed during the growth run and (b) excess arsenic vapor is introduced at the beginning of the growth. In layers grown under high arsenic vapor pressure, the high resistance region does not exist and instead a very thin low resistance region appears at the interface. Such phenomena are qualitatively interpreted as due to the deviation of arsenic vapor pressure from that in the steady state condition in the reaction system.
Hall measurement on the high resistance region at different temperatures shows that the high resistance is due to deep acceptors whose energy level is approximately 0.5 eV from the valence band edge and which are inferred to be related with arsenic vacancy.
Effect of Heat Treatment on the Interface Characteristics in Reactively Sputtered Al2O3-Si Structures
Authors: Hattori Takeshi , Iwauchi Shigeki , Nagano Katsuto , Tanaka Toshio
Published: September 2006

Aluminum oxide (Al2O3) silicon MOS structures formed by DC reactive sputtering of pure aluminum in a low pressure oxygen ambient are subjected to heat treatments in various environments, and the interface characteristics of these structures are evaluated.
The surface state density at the Al2O3-Si interface is found to be diminished by annealing in a nitrogen ambient, and be reduced further by additional heat treatment in a hydrogen ambient over a comparatively wide energy range.
Helical Instability of a Linear Discharge Plasma Produced by a Large Capacity Condenser Bank
Authors: Enjōji Hiroshi , Okamoto Kousuke
Published: September 2006

Helical instability of a linear discharge plasma produced by an electrolytic condenser bank is investigated with a streak camera. The capacity and the working voltage of the bank are 1.1×104 µF and 500 volts respectively. The process of formation of the helical plasma is observed. The formation of the helix started about 20 µsec after the initiation of discharge, and the helix rotates with an angular velocity of several degrees per microsecond. The validity of Shafranov's condition for a stable plasma is experiment ally verified. Regular ripples superimposed on the wave forms of the voltage and current pulses corresponded to the rotation of plasma stripes.
X-Ray Photoelectron and Anger Electron Spectroscopic Studies of Chemical Shifts in Amorphous Ge–Se System
Authors: Ueno Tokihiro
Published: September 2006

The chemical shifts of the Ge 3d, 3p3/2,1/2 and Se 3d, 3p3/2,1/2 photoelectron lines were measured for the amorphous Ge–Se system and those of the Ge photoelectron lines are corrected for Auger parameter shifts. According to the valence shell potential model, the ratio of the chemical shift in the amorphous Ge–Se system to that in stoichiometric GeSe2 can be approximated by the ratio of the Ge–Se bond number in the Ge–Se system to that in GeSe2. The chemical shift ratios evaluated from the experimental results reveal bond structures at non-stoichiometric compositions. In the excess-Ge range, GeSe is composed of atomic clusters of three-fold co-ordinated Ge and Se atoms, and Ge2Se3 contains atomic clusters of Se3Ge–GeSe3 units. In the excess-Se range, GeSe3 includes GeSe4 tetrahedral units, and Se–Se chains and/or Se8 rings.
Solid Composition and Growth Rate of Ga1-xAlxAs Grown Epitaxially by MOCVD
Authors: Takahashi Yasuhito , Soga Tetsuo , Sakai Shiro , Umeno Masayoshi , Hattori Shuzo
Published: September 2006

The effects of the growth temperature and the total hydrogen flow rate on the solid composition and the growth rate in the MOCVD growth of Ga1-x
Al
x
As were investigated in detail. It was found that (1) the rate of incorporation of Ga atoms decreased with increasing growth temperature, while that of Al atoms increased up to 780°C and decreased beyond 780°C; (2) an increase in the total gas flow rate had the effect of reducing the boundary layer thickness and lowering the surface temperature of the wafer; and (3) there was no interaction between Ga and Al atoms in the growth of Ga1-x
Al
x
As. The detailed experimental results are described in this paper.
Influence of Growth Temperature on the Optical Properties of (YBi)3(FeGa)5O12 Film Waveguides
Authors: Okamura Yasuyuki , Nakamura Takashi , Yamamoto Sadahiko
Published: September 2006

We report measurements of the optical properties of bismuth and gallium substituted yttrium iron garnet films deposited on GGG substrates by the LPE method for use as integrated optical waveguides. Emphasis is placed on the effect of the growth temperature. As the degree of supercooling was increased from 0.02 to 0.1 for a melt whose saturation temperature was 985°C, the refractive index of the film varied from 2.17 to 2.23 and the Faraday rotation varied from 200 to 800 degree/cm at a wavelength of 1.15 µm. However, the mode propagation loss was constant at nearly 10 dB/cm regardless of the growth temperature.
Ionizing Radiation Effects in MOS Capacitors with Very Thin Gate Oxides
Authors: Shiono Noboru , Shimaya Masakazu , Sano Koichi
Published: September 2006

The positive oxide charge buildup and interface trap generation by γ-ray irradiation in MOS structures have been investigated as a function of gate oxide quality, gate oxide thickness, and applied oxide field. The radiation-induced shift in the flat-band voltage V
FB is shown to have a maximum at a field of about 2 MV/cm, and a minimum at the flat-band bias. The dependence of the shift in V
FB on the oxide field becomes weaker with decreasing gate oxide thickness. A large number of interface traps are generated under a positive oxide field, whereas the number of interface traps generated under a negative oxide field is negligible. Si–OH bond breaking at the Si–SiO2 interface, enhanced by hole capturing, is proposed as the dominant mechanism for interface trap generation. The formation of very thin gate oxides (∼10 nm) by dry O2 oxidation is also shown to be a highly-promising process for fabricating radiation-hardened MOS devices.
A Study of an Absolute Determination of the Magnetic Flux Quantum Using a Superconducting Levitation System
Authors: Shiota Fuyuhiko , Hara Ko , Hirata Takaaki
Published: September 2006

A study on a new method of determining the magnetic flux quantum φ0 possibly at subppm level using a superconducting levitation system is described with some data from a preliminary experiment. The method employs a superconducting levitation system to substitute the gravitational potential energy of the floating body for the magnetic energy. The estimation of the expected accuracy and methods of improving the experiment are discussed.
A Statistical Study of Fish Movement in an Aquarium
Authors: Sato Tadashi , Terao Kunio
Published: September 2006

In order to observe the motion and behavior of a fish statistically, an optical apparatus connected to a microcomputer was designed. Using this apparatus, the position of a goldfish at an arbitrary time was measured in an aquarium and the one-dimensional distributions of the position and the speed were obtained. The experimental results show that the position distribution decreases exponentially with respect to increasing distance from the wall, while the speed distribution is independent of the position in the aquarium. Assuming one-dimensional asymmetric random walk and complete reflection at the wall, the exponential distribution of the fish's position is predicted theoretically.
High-Energy Particles in AlN Film Preparation by Reactive Sputtering Technique
Authors: Tominaga Kikuo , Iwamura Satoshi , Shintani Yoshihiro , Tada Osamu
Published: September 2006

AlN films were prepared by reactive DC planar magnetron sputtering in atmosphere of N2 gas or mixed gas of N2 and H2. High-energy neutral particles bombarding the AlN film were observed by using a time-of-flight particle analyzer. It is found that the high-energy particles such as NO and OH (or O) due to residual H2O in the discharge chamber or oxides at the Al target surface induce the coloring of film, the decrease of optical transmittance at shorter wavelength, the decrease of the degree of c-axis orientation of the film, etc. For the sputtering in mixed gas of N2 and H2, a number of energetic H atoms are bombarding the AlN film. The influence of these energetic H atoms on the film growth is also studied.
A New Ultrasonic Cell for Measurement near Melting Point of Metal
Authors: Kamioka Hiroaki
Published: September 2006

A new ultrasonic cell for measurements of ultrsaonic velocity and attenuation in a metal under both conditions of melting and solidifying processes has been designed. Ultrasonic pulse transmission method has been used in the present work. As an example, by using a new ultrasonic cell, sound velocity of Wood's alloy is measured at and around the melting temperature, and the results for the change of sound velocity in the vicinity of the melting point are reported and discussed.
Liquid-Phase Epitaxial Growth of ZnSe on ZnTe Substrate
Authors: Nakamura Hiroshi , Sun Liang Yan , Asano Akihiko , Nakamura Yuichi , Washiyama Masako , Aoki Masaharu
Published: September 2006

Epitaxial layers of ZnSe were grown on ZnTe substrates using a liquid-phase epitaxial growth (LPE) method. A presynthesized Te–Se solution was used as a solvent for LPE. Growth was done in an evacuated quartz tube by a tipping method. The Zn–Se–Te ternary phase diagram was also determined in order to take the basic data of the LPE growth. The ZnSe/ZnTe heterostructure showed fairly good photovoltaic properties. The open-circuit voltage was 0.9 V and the ZnSe epilayer was effective as a window material of the solar cell.
Measurement of Sub-Nanosecond Single-Rovibronic Fluorescence with a Pulsed Dye Laser
Authors: Suzuki Takanori , Yamada Koichi , Kasuya Takahiro
Published: September 2006

A method of fluorescence-decay measurement of sub-nanosecond time-resolution is presented which employs a narrow band pulsed dye laser for molecular excitation and a computer-controlled waveform digitizer for decay-data recording. The kinematical parameters of single rovibronic molecular relaxation are thereby deduced routinely from the observed time-evolution of fluorescence decay through a curve-fitting procedure of convolution-integral treatment. A specimen observation of fluorescing dye solution demonstrates the capability of determining fluorescence decay time as short as 0.2 ns with a precision of better than ±0.05 ns. The method was applied to a systematic single rovibronic observation of fluorescence from the predissociative state of interhalogen molecule.
Beam-Plasma Type Metal Ion Source
Authors: Ishikawa Junzo , Takagi Toshinori
Published: September 2006

A metal ion source, whose operation is based on a beam-plasma type ion source, has been developed. Heating of a plasma production chamber (1160°C) and generation of axial magnetic field (0.029 T) were both achieved by DC current flow through a solenoid filament. A continuous ion current of 2–3 mA (Ag, Al, Sb, Mn, Pb) was extracted from a single aperture at a low extraction voltage of 5.2 kV; this was due to a high density plasma production by means of beam-plasma discharge and an ion extraction with ion space-charge compensation by beam electrons and high energy plasma electrons. For the case of silver ion beam, a silver ion current with a purity of 99.5% was extracted without a mass analyzer. Normalized emittance and normalized brightness were 1.9×10-8 m·rad and 1.1×1011A·rad-2·m-2, respectively.
Effects of rf Power and Substrate Temperature on Properties of a-SiNx:H Films Prepared by Glow-Discharge of SiH4–N2–H2
Authors: Watanabe Hideo , Katoh Kazuhisa , Yasui Masaru
Published: September 2006

Amorphous SiN
x
:H films were prepared by the rf glow-discharge of gaseous mixtures of SiH4–N2–H2 at various substrate temperatures and rf power densities. The nitrogen and hydrogen contents of the films were determined from the intensities of the IR absorption due to vibrations of Si–N bonds and Si–H bonds. The effects of these deposition parameters on the properties of the amorphous films are discussed on the basis of the variation of the composition and structure of the films.
Atomic Scattering Factors of Zn Determined from Measurement of X-Ray Pendellösung Intensity Beats Using White Radiation
Authors: Takama Toshihiko , Kobayashi Kazuyoshi , Hyugaji Masahiko , Nittono Osamu , Sato Shin'ichi
Published: September 2006

The Pendellösung intensity beats of white radiations diffracted from Zn single crystals grown by a solidification method have been measured by the energy-dispersive diffraction technique using a solid-state detector. The atomic scattering factors of Zn were evaluated by measuring the positions of the intensity extrema and utilizing the dynamical diffraction theory for the eight low-order reflections. The absolute atomic scattering factors were found to be smaller than those calculated for free atoms by the relativistic Hartree-Fock method, especially for low-order reflections, as well as for the reflections from the basal plane. The result suggests that the outer electrons diffuse out, particularly in the direction of the C-axis, from the spherical electron clouds in Zn atoms in the crystals.
New Far Infrared Laser Emissions from D2CO and H2CO Optically-Pumped by a TECO2 Laser
Authors: Horiuchi Yasuo , Nishi Yoshio , Sokabe Noburu , Murai Akira
Published: September 2006

H2CO and D2CO were optically-pumped by a TE CO2 laser and found to generate 7 and 64 new far infrared (FIR) lines, respectively. Most of the previously-reported D2CO cw FIR lines were also produced well. With an intracavity low-pressure cw CO2 gain cell, these previously reported cw FIR lines were found to oscillate efficiently. A well-developed cascade laser action and the oscillation of the cw FIR lines are the characteristic properties of a formaldehyde FIR laser pumped by a TE CO2 laser. The origin of these properties is discussed, and it is suggested that a large electric dipole moment along the symmetry axis and small pump offsets probably play an important role.
Thermodynamic Calculation of the VPE Growth of In1-xGaxAs by the Trichloride Method
Authors: Koukitu Akinori , Seki Hisashi
Published: September 2006

A method of computation developed for analysing the equilibrium state of a multicomponent system, has been extended to the epitaxial growth of In1-x
Ga
x
As performed by the trichloride (AsCl3) method. The general features of the equilibrium partial pressures are found to be similar to those of the hydride system. The deposition diagram is computed as a function of the input mole ratio, and the effect of the growth parameters on the composition of the deposit is discussed in comparison with other techniques. It is shown that the thermodynamic model can explain the slow growth rates observed in both the trichloride and the single flat-temperature zone methods.
Hot Electron Energy Distribution in Spherical Cannonball Target at 10.6 µm Laser Wavelength
Authors: Daido Hiroyuki , Terai Kiyohisa , Fujita Masayuki , Miki Futoshi , Nakai Sadao , Yamanaka Chiyoe
Published: September 2006

Hot electron energy distributions in spherical Cannonball targets at 10.6 µm laser wavelensth were measured using the multi-layered target technique and the Monte Carlo electron transport code. In the inner pellet irradiation type of target, a high energy component of the hot electron energy distribution is strongly reduced from Maxwellian, leading to lower preheating.
Silicon Epitaxial Growth by the Radical Beam of Glow-Discharge Decomposed Silane
Authors: Maruno Shigemitsu , Isu Toshiro , Ogata Hitoshi
Published: September 2006

Epitaxial films of silicon on silicon were formed by the radical beam produced by glow-discharge decomposition of SiH4. The radical beam was effused to a substrate located in the growth region through an orifice which separated the film growth region from the discharge region. Film formation took place whenever the mean free path of radical species was larger than the distance between the orifice and the substrate. Epitaxial growth occurred at the substrate temperature above 550°C. The epitaxial films had mirror-like surfaces.
Picosecond Pulse Generation by Self-Phase Modulation in an Actively Mode-Locked and Q-Switched Phosphate Glass Laser
Authors: Tomie Toshihisa
Published: September 2006

The generation of 4 ps pulses by an actively mode-locked and Q-switched phosphate glass laser is reported. The pulse width is found to decrease rapidly after the peak of the Q-switched pulse train, accompanied by distortion of the pulse temporal profile from the initial Gaussian shape. Theoretical analysis demonstrates that pulse shortening takes place when the phase-modulated pulse passes through the etalon in the laser cavity. Modulation in the phase of the pulse is caused by the nonlinear refractive indices of the laser rod and the two acousto-optic elements used for mode-locking and Q-switching.
Analysis of Compositional Variation at Initial Transient Time in LPE Growth of InGaAsP/GaAs System
Authors: Hiramatsu Kazumasa , Tanaka Shigeyasu , Sawaki Nobuhiko , Akasaki Isamu
Published: September 2006

The variation of the solid composition x at the initial stage of the LPE growth of In
x
Ga1-x
As
y
P1-y
(y<0.01) on GaAs from the supersaturated solution is studied by the diffusion-limited growth model using the diffusion coefficients of Ga and P in In solution. The growth lines on the In-Ga-P phase diagram are calculated by solving the diffusion equations and the phase equilibrium equations simultaneously, and it is found that the compositional variation takes place at a time of less than 5 s, and depends strongly on the initial supersaturation. By comparing the results with the experimental ones obtained from X-ray diffractometry measurements, the diffusion coefficients of Ga and P in the In-Ga-P solution are determined as D
Ga=1.3 ×10-4 cm2/s and D
P=2.3 ×10-4 cm2/s, respectively.
Characterization of Precipitates in Anodic Oxidized Ga1-xAlxAs and Ga1-xInxAs by Laser Raman Spectroscopy
Authors: Eguchi Kazuhiro , Katoda Takashi
Published: September 2006

The effects of adding Al or In to GaAs on precipitates and their distribution in anodic oxides were studied using laser Raman spectroscopy. Crystalline As precipitated from Ga1-x
Al
x
As (0 ≤x ≤0.54) and Ga1-x
In
x
As (0 ≤x ≤0.15), while no species precipitated from Ga1-x
In
x
As (0.53 ≤x ≤1) after annealing in a nitrogen atmosphere at a temperature higher than 430°C. On the other hand, amorphous species precipitated from Ga1-x
In
x
As (0 ≤x ≤1) and no species precipitated from Ga1-x
Al
x
As (0.22 ≤x ≤0.54) after annealing in a hydrogen atmosphere at a temperature higher than 400°C. The crystalline As is produced by a solid-state interfacial reaction at the oxide/semiconductor interface, while the amorphous species is produced by the reduction of oxides.
Thermal Degradation of InP/InGaAsP/InP DH Structure
Authors: Komiya Satoshi , Tanahashi Toshiyuki , Umebu Itsuo
Published: September 2006

LPE-grown undoped InP/InGaAsP/InP samples were annealed under a phosphorus pressure produced by either an InP cover piece, phosphine or red phosphorus. The change in photoluminescence (PL) intensity of the quaternary layer before and after annealing was investigated as a function of the excitation power density. Even when annealed under a phosphorus pressure, a condition under which surface degradation is never observed, the PL intensity decreases. The rate of decrease of the PL intensity depends on the excitation power density. Because the rate is independent of the quaternary layer thickness, the decrease in the PL intensity is ascribed to a decrease in the internal quantum efficiency of the quaternary layer rather than to an increase in the interface recombination velocity. Furthermore, the dependence of the decrease in PL intensity on the excitation power was analyzed theoretically and the non-radiative carrier lifetime estimated. The thermal degradation of double heterostructure (DH) samples can be evaluated even when the surface remains unchanged.
Vapor Growth of Al-Doped ZnTe by the Closed-Tube Method
Authors: Seki Akinori , Okazaki Masayuki , Kakehi Masahiro , Kitamura Noboru , Wada Takao
Published: September 2006

The vapor growth of n-type ZnTe on as-grown ZnTe and GaSb substrates was examined at comparatively low temperature by the conventional closed-tube process using minute amounts of iodine as the transport agent. Polycrystalline ZnTe doped with either 5 or 10 mol% Al was used as the source crystal in the doping experiment.
A uniform over-growth of ZnTe on the substrates was observed when iodine at a density of 0.6–13×10-5 mg/cm3 was introduced into the reaction tube and vapor growth in the 650–675°C system was carried out rather than in the 600–625°C or 625–650°C systems.
SIMS measurement showed that the ZnTe layer was doped with a considerable amount of Al. The hot-probe method showed n-type conduction in the layer.