bluuebunny/crossref_metadata_2025 huggingface dataset:
Skin irritation typing and grading based on laser Doppler perfusion imaging
Authors: Fullerton Ann , Rode Birgitte , Serup Jørgen
Published: July 2002

Background/aims: Vasodilation with increased cutaneous perfusion is an essential part of an irritant inflammatory response. The aim of the present study was to investigate the usefulness of the high‐resolution laser Doppler perfusion imaging (HR‐LDPI) technique for investigating irritant skin reactions. Irritants may elicit clinically different reactions due to different skin penetration profiles and different modes of irritant action on the exposed tissue.

Methods: Twelve subjects were tested on the forearms using 24 h occlusive application of three concentrations of the irritants sodium lauryl sulphate (SLS) and nonanoic acid (NON) and with the topical acne drug all‐trans retinoic acid (RA). Cutaneous blood flow at baseline, the increase in cutaneous blood flow and the skin area having increased perfusion were measured on day 2, day 3 and day 5.

Results: Based both on measurement of mean perfusion and area with increased perfusion, it was possible to differentiate between different clinical irritation grades on any study day. The area with increased perfusion exceeded the area with clinically visible skin reactions for irritant reactions of grade 1/2 and above. Irritant reactions for individual irritants could furthermore be typed using HR‐LDPI. It was possible to differentiate between vehicle treatment and the different dose levels of the irritant compounds. A correlation was found between clinical scores for the individual irritants and the mean flow and the area with increased flow. The individual irritants could be differentiated due to different time courses of their skin irritation.

Conclusion: Laser Doppler imaging was found to be an important new method for characterization and grading of the inflammatory response of single exposure irritant reactions. However, standardised study procedures cannot be emphasised enough in order to obtain reliable and useful data.
Cloning, structural characterization and functional expression of a zebrafish bradykinin B2-related receptor
Authors: DUNÉR Torun , CONLON J. Michael , KUKKONEN Jyrki P. , ÅKERMAN Karl E.O. , YAN Yi-Lin , POSTLETHWAIT John H. , LARHAMMAR Dan
Published: July 2002

The actions of bradykinin (BK) in mammals are mediated through the activation of the B1 and B2 BK receptors. The only BK receptor that has been cloned from a non-mammalian species is a B2-like receptor from the chicken (termed the ornithokinin receptor). Pharmacological studies have demonstrated the presence of BK receptors in tissues of teleost fishes, such as trout and cod, but the ligand-binding properties of these receptors differ appreciably from those of the mammalian and chicken receptors. We report here the cloning of a B2-like receptor in zebrafish that shares 35% identity with human B2 and 30% identity with human B1. Phylogenetic analyses confirm a closer relationship with B2 than B1. The receptor gene was mapped to linkage group 17, which is syntenic to the human B2—B1 gene region. After functional expression of the zebrafish B2 receptor in mammalian cells, nanomolar concentrations of trout BK ([Arg0,Trp5,Leu8]-BK) and the derivative [des-Arg0,Trp5,Leu8]-BK (where ‘des’ indicates a missing amino acid) induced a significant transient rise in intracellular free Ca2+. The B1-selective analogue [Arg0,Trp5,Leu8,des-Arg9]-BK was inactive at nanomolar concentrations. Taken together, these results strongly support the gene's identity as a piscine orthologue of the mammalian B2 receptor.
Genome Multiplication in Trophoblast Giant Cells of Sheep, Goat, Water Buffalo and Deer: an Image Cytophotometric Study
Authors: Klisch K , Schuler G , Miglino MA , Leiser R
Published: July 2002

Contents

DNA contents of nuclei from sheep (Ovis aries), goat (Capra hircus) (each n = 2), water buffalo (Bubalus bubalis) (n = 4), and deer (Dama dama) (n = 1) placentomes were measured cytophotometrically. In all specimens nuclei with approximately 8C DNA content were found. These findings, in addition to earlier results on bovine trophoblast giant cells (Klisch et al. Placenta 20, 451–458, 1999), indicate that genome multiplication is a normal feature of the development of ruminant trophoblast giant cells
Effects of sciatic nerve injuries on δ ‐opioid receptor and substance P immunoreactivities in the superficial dorsal horn of the rat
Authors: Robertson Brita , Schulte Gunnar , Elde Robert , Grant Gunnar
Published: July 2002

The aim of the present study was to examine the effects of transection combined with tight ligation, and crush of the sciatic nerve on δ ‐opioid receptor and substance P immunoreactivities in the superficial spinal dorsal horn at different time points after injury. Both the δ ‐opioid receptor and substance P are primarily localised to primary afferent fibres and terminals. Seven days following transection and ligation, a slight decrease in both δ ‐opioid receptor and substance P levels was seen in laminae I and II. The maximal reduction appeared to take place around 4 weeks. Restoration of immunoreactivity was observed by 32 weeks, and by 1 year the levels were almost back to normal. Regarding crush injury, the reduction in both δ ‐opioid receptor and substance P immunoreactivities were less pronounced and recovery was faster than after transection injury. Already by 16 weeks, the levels were almost back to normal.

These results show that peripheral nerve injuries dramatically reduce the levels of δ ‐opioid receptor and substance P immunoreactivities in the superficial dorsal horn after short survivals and demonstrate recovery after long survivals. Whether the marked reduction of δ ‐opioid receptors in the dorsal horn is involved in the decreased ability of opioid analgesics to alleviate neuropathic pain remains to be studied.
Cyclophosphamide cystitis in mice: Behavioural characterisation and correlation with bladder inflammation
Authors: Olivar Teresa , Laird Jennifer M.A.
Published: July 2002

The generation of transgenic ‘knock‐out’ mice which lack genes relevant to pain is becoming increasing common. However, only one visceral pain model, the writhing test, is available in mice. The aim of this study was to adapt cyclophosphamide cystitis, a model of inflammatory visceral pain described in rats, for use in mice, and to characterise its behavioural effects. The toxic metabolites of systemically‐administered cyclophosphamide are excreted in the urine, and induce bladder inflammation. We compared the effects of cyclophosphamide (100 and 300 mg/kg i.p., 4 h survival period) and vehicle (saline) in male mice on spontaneous behaviour (4 h continuous video‐tape, and a 5‐min Open Field test after 4 h). Involvement of the urinary bladder and other abdominal tissues was assessed by macroscopic examination and measurement of Evan's Blue plasma extravasation. Cyclophosphamide (300 mg/kg) produced significant changes in behaviour, including 22 ± 6 min of ‘crises’ of visceral pain‐related behaviour and a 53% reduction in activity, and also induced haemorrhage and substantial plasma extravasation in the bladder, but no change in other abdominal tissues. We conclude that cyclophosphamide cystitis has many advantages as a model of sub‐acute, inflammatory visceral pain in mice. It does not require surgery or intubation, and we have found it to produce consistent, reproducible and quantifiable behavioural changes, which are significantly correlated with the degree of bladder inflammation in the absence of inflammation of other abdominal tissues.
Generation of 0.6 μJ pulses of 16 fs duration through high-repetition rate amplification of self-phase modulated pulses
Authors: Boyer G. , Franco M. , Chambaret J. P. , Migus A. , Antonetti A. , Georges P. , Salin F. , Brun A.
Published: July 2002

We have generated optical pulses of 16 fs duration in the submicrojoule range and at a repetition rate of 11 kHz. This was obtained by amplifying self-phase modulated pulses at the output of a fiber, using a couple of dyes to achieve gain covering a large spectrum around 620 nm.
Angled etching of GaAs/AlGaAs by conventional Cl2 reactive ion etching
Authors: Takamori Takeshi , Coldren Larry A. , Merz James L.
Published: July 2002

Angled etching of GaAs and GaAs/AlGaAs double heterostructures was achieved in a conventional Cl2 reactive ion etching system. A new angled holder, which has a recessed groove structure where the substrate is positioned, was used to eliminate bending of the ion trajectory around the substrate. The facet angle is accurately determined by the angle of the groove wall. Equal etching rates and smooth facets were obtained by using a load-locked system and trilevel photoresist masking. This simple dry etch process is suitable for the formation of optoelectronic integrated circuits such as surface-emitting lasers.
Laser action in chromium-activated forsterite for near-infrared excitation: Is Cr4+ the lasing ion?
Authors: Petričević V. , Gayen S. K. , Alfano R. R.
Published: July 2002

Room-temperature pulsed laser action has been obtained in chromium-activated forsterite (Cr:Mg2SiO4) for excitation of the near-infrared absorption band of the system by the 1064 nm radiation from a Nd:YAG laser. The characteristics of laser emission are similar to those observed for 532 nm pumping. It is suggested that the laser action is due to a ‘‘center’’ other than the trivalent chromium (Cr3+), presumably the tetravalent chromium (Cr4+).
New dual-bath technique for electrodeposition of short repeat length multilayers
Authors: Goldman L. M. , Ross C. A. , Ohashi W. , Wu D. , Spaepen F.
Published: July 2002

An electrodeposition technique for making multilayered thin films, based on controlled deposition from two different solutions, is described. Ni/NiPx and NiPx/NiPy multilayered thin films with repeat lengths as low as 20 Å have been prepared. They show up to three low-angle x-ray peaks corresponding to the electron density modulation.
Novel contactless electroreflectance spectroscopy of semiconductors
Authors: Gal M. , Shwe C.
Published: July 2002

Optical reflectance difference technique has been applied to semiconductors. It has been demonstrated that differential reflectance spectroscopy (DR) can be equivalent to contactless electromodulation. The measured DR spectra of GaAs are comparable to the published electroreflectance data and show marked improvement in the signal-to-noise ratio over the photoreflectance spectra of the same samples. We have used this method to study the confined energy levels in InGaAs/GaAs multiple quantum wells and have found good agreement with the theoretically predicted values. We conclude that DR is a viable alternative to photoreflectance as a contactless electromodulation technique.
Origin of anomalous energy spreads in photoelectron beams
Authors: Drouhin H.-J. , Bréchet Ph.
Published: July 2002

The use of photocathodes as intense monoenergetic electron sources seems very promising. Yet, many experimenters have observed large energy spreads, increasing with the emitted current, which remained unexplained. Here, we analyze a mechanism which accounts well for these effects.
High-brightness pseudospark-produced electron beam
Authors: Boggasch E. , Rhee M. J.
Published: July 2002

The first time-integrated root mean square (rms) emittance measurement of a pseudospark-produced electron beam is presented. From a six-gap pseudospark chamber with argon working gas, ∼10 Hz repetitive pulsed electron beams of average energy ∼20 keV, peak current ∼50 A, and pulse duration ∼10 ns are extracted into a drift tube. A typical value of measured rms emittance is found to be ε≊55 mm mrad, yielding a normalized rms emittance of εn≊15 mm mrad. The normalized brightness of the beam is then estimated to be Bn≊4×1010 A/(m2  rad2 ).
Enhanced etching of silicon in CF4-O2-N2 plasma
Authors: Premachandran V.
Published: July 2002

It is shown that a threefold increase in the etch rate of silicon can be achieved with the addition of 1% of nitrogen into the CF4-O2 plasma. An increase in the atomic fluorine concentration is shown to be responsible for this enhancement in the etch rate.
Role of long-lived species in pulsed hollow cathode discharges in N2
Authors: Choi P. , Kaufman Y. , Aliaga R.
Published: July 2002

Experiments in pulsed hollow cathode discharges demonstrate that long-lived species, with lifetime of the order of seconds, play a significant role in the formation of the discharge in nitrogen. Detailed studies show that the effect is strongest in the hollow cathode region. Similar effects are not observed in hydrogen. A simplified model of the destruction of the N2(A3Σ+u) state has been adopted to study the relevance of this level. The possible roles of the metastables in the formation of pulsed hollow cathode discharges are discussed.
High-resolution, tunneling-stabilized magnetic imaging and recording
Authors: Moreland John , Rice Paul
Published: July 2002

We have used a scanning tunneling microscope (STM) to record and image magnetic regions on the surface of a hard disk. The usual rigid STM tip was replaced by a compliant magnetized Fe film tip. As a result, tunneling images were combinations of the surface topography and variations in the magnetic force between the Fe film tip and the disk surface. We believe that the recording process relied on maintaining the proximity of the magnetized Fe film tip near the disk surface. Apparently, the magnetic field was focused near the Fe film tip with sufficient intensity to change the surface magnetization of the disk. We have recorded spots on the disk within a 500 nm×500 nm area. These spots were subsequently imaged with the same STM tip. Our best magnetic image resolution was 20 nm. The compliance of the Fe film tips was such that image contrast due to variation of the magnetic force on the tip corresponded to z motions of the piezoelectric translator as large as 50 nm.
Two-photon absorption as a limitation to all-optical waveguide switching in semiconductors
Authors: DeLong K. W. , Stegeman G. I.
Published: July 2002

The dispersion of a parameter quantifying the effects of two-photon absorption on all-optical waveguide switching devices is evaluated for the case of semiconductors in a two band model. Serious limitations are predicted based on the nonresonant bound electron response for photon energies between the band gap and one half the band gap.
Differential reflectance spectroscopy of InGaAs/GaAs and AlGaAs/GaAs quantum wells
Authors: Shwe C. , Gal M.
Published: July 2002

A differential reflectance (DR) technique has been used to study InGaAs/GaAs and AlGaAs/GaAs quantum wells. DR was measured on ‘‘as-grown’’ layers, relying solely on the spatial variation of the quantum well parameters for the differential reflectance signal. The DR spectra of AlGaAs/GaAs and InGaAs/GaAs quantum wells exhibited sharp structures corresponding to the anticipated light and heavy hole excitons. The signal-to-noise ratio of the DR spectra was considerably better than the photoreflectance spectra measured on the same samples. We concude that DR is an effective and practical technique at room temperature for the study and characterization of semiconductor quantum wells and superlattices.
Preferential reaction and stability of the Au-Sn/Pt system: Metallization structure for flip-chip integration
Authors: Wada Osamu , Kumai Tsugio
Published: July 2002

Thermal reaction of a metallization system consisting of Au-Sn solder, Pt/Ti barrier, and Au/Zn/Au contact layers formed on an InP substrate has been studied using Auger electron spectroscopy, scanning electron microscopy, and x-ray diffractometry. Upon heating to 400 °C, no degradation of the Au/Zn/Au contact was noticed and moderate reaction was observed between Au-Sn and Pt. The reaction shows a characteristic feature of preferential Pt-Sn interdiffusion to produce an intermediate layer involving the PtSn phase. The effective diffusion coefficient exhibits an activation energy of 1.35 eV. The lifetime of this Pt barrier has been determined to be in excess of 108 h for 50 °C, being sufficient for the application of this metallization structure in practical device and flip-chip integrated circuit fabrication.
Spectroellipsometry characterization of optical quality vapor-deposited diamond thin films
Authors: Cong Yue , Collins R. W. , Epps Glenn F. , Windischmann H.
Published: July 2002

Quantitative characterizational methods are required to optimize vapor-deposited diamond thin films for optical applications. In this work, spectroellipsometry has been applied to deduce two important characteristics of diamond films: the volume fraction of sp2-bonded defects in the bulk and the thickness of the roughness layer on the surface. We have determined these characteristics versus substrate temperature and CH4:H2 flow ratio for optical quality films prepared to 1000–4000 Å by microwave plasma-assisted chemical vapor deposition. Under optimum conditions, uniform films with ∼100 Å roughness and 3 vol.% bulk sp2C are obtained.
How far does the charge state affect the iron behavior in silicon?
Authors: Heiser T. , Mesli A.
Published: July 2002

Low-temperature precipitation of neutral interstitial iron in n-type silicon is investigated by means of photocapacitance measurements. Isothermal kinetics as well as iron depth profiles are observed which agree very well with an outdiffusion mechanism of iron to the sample surface. From these data the diffusion coefficient of neutral iron in silicon could be determined. Comparison with published results on positively charged iron in p-type silicon reveals a higher stability of neutral iron as well as a charge state dependence of its diffusion mechanism.
Hydrogen induced detrapping of transition metals in amorphous silicon
Authors: Coffa S. , Poate J. M.
Published: July 2002

The implantation of H into amorphous Si is shown to passivate the structural defects that act as traps for fast diffusing transition metal impurities such as Cu or Pd. The depth distributions of Cu or Pd, as determined by Rutherford backscattering spectrometry, are governed by the H distribution for concentrations up to 5 at. % and temperatures between 250 and 500 °C. The H can cause complete detrapping of the metal impurities leaving a Gaussian deficit in their equilibrium distributions mirroring the H depth distribution. The H is thus more strongly bonded to the traps than Cu or Pd. The total trap concentration is estimated to be 2.2±0.9 at. % for 350 °C annealing. Implanted F also induces detrapping of Cu and Pd. These detrapping phenomena demonstrate equivalence between the structural traps that control diffusive properties and the defects that control electrical and optical properties.
Electron cyclotron resonance assisted low temperature ultrahigh vacuum chemical vapor deposition of Si using silane
Authors: Mui D. S. L. , Fang S. F. , Morkoç H.
Published: July 2002

Deposition of single-crystal homoepitaxial Si at low temperatures assisted by an electron cyclotron resonance (ECR) generated plasma using a mixture of helium and silane gases in an ultrahigh vacuum chemical vapor deposition (UHVCVD) chamber is reported. The pure silane gas is introduced into the UHVCVD chamber through a showerhead located above the substrate and is excited indirectly by the helium plasma brought downstream from the ECR chamber. At a chamber pressure of 5×10−4 Torr epitaxial single-crystal Si can be obtained at a substrate temperature Ts as low as 400 °C. Variation of the deposition rate with respect to the microwave power, Pμ, at different temperatures suggests a hydrogen inhibited deposition process at low temperatures. At 460 °C the deposition rate increases with Pμ below 60 W and saturates for Pμ beyond this value. On the other hand, at a Ts of 610 °C, this saturation effect is not observed and the deposition rate increases linearly with Pμ. In this plasma-assisted deposition, a much reduced Ts dependence of the deposition rate is observed. We have used this deposition technique successfully in obtaining a Si3N4/(epi-Si) metal-insulator-semiconductor capacitor with an interface trap density of 2×1010 eV−1 cm−2 as determined by the conductance method.
Internal stress reduction by nitrogen incorporation in hard amorphous carbon thin films
Authors: Franceschini D. F. , Achete C. A. , Freire F. L.
Published: July 2002

Results of a study on internal stress, hardness, and structure of nitrogen-doped amorphous hydrogenated hard carbon films deposited by rf glow discharge from methane-nitrogen mixtures onto silicon substrate are presented. Films obtained for different N2 partial pressures (bias voltage Vb=−370 V and total pressure P=8 Pa) were characterized by infrared spectroscopy, Raman scattering, and nuclear techniques. The elemental composition, density, and structure are correlated with Vickers hardness and internal stress values, obtained from the substrate bending method. It has been observed that internal stress considerably decreases with increasing nitrogen content, in contrast to hardness, structure, and hydrogen concentration, which remain unchanged.
Rapid modulation of interband optical properties of quantum wells by intersubband absorption
Authors: Gorfinkel Vera B. , Luryi Serge
Published: July 2002

Intersubband absorption of radiation by a two-dimensional electron gas can be used to control the electron temperature and effect a significant modulation of the interband optical properties of the semiconductor in the quantum well. We discuss the implementation of a fast modulator of infrared radiation for fiber-optical communications as well as the formation of powerful and short single-mode infrared pulses.
Positively charged surface potential of polymer films after excimer laser ablation: Application to selective-area electroless plating on the ablated films
Authors: Niino Hiroyuki , Yabe Akira
Published: July 2002

Pulsed laser ablation of poly(ethylene terephthalate), polyimide, and polyethersulfone films has been investigated by surface potential analysis on the ablated films. After irradiation with XeCl or KrF excimer laser in air, the surface potential of these films changed to a positive potential mainly due to the redeposition of cationic fragments onto the ablated area. On the basis of the potential analysis, the electroless plating (chemical plating) of copper or nickel was carried out selectively on the ablated surface of these films, through a surface activation process using a negatively charged colloid.
Si-implanted InGaP/GaAs metal-semiconductor field-effect transistors
Authors: Hyuga Fumiaki , Aoki Tatsuo , Sugitani Suehiro , Asai Kazuyoshi , Imamura Yoshihiro
Published: July 2002

A new device structure for Si-implanted GaAs metal-semiconductor field-effect transistors (MESFETs), with an InGaP thin film on the GaAs surface, is proposed. A 200 Å InGaP film passivated the GaAs surface and increased the Schottky barrier height on n-type GaAs layers with a carrier concentration as high as 3×1018/cm3 to more than 0.6 eV. These effects persisted after annealing at 800 °C for 10 min. The transconductance of 2-μm-gate MESFETs remained above 150 mS/mm at gate voltages up to 1.0 V. Si-implanted InGaP/GaAs MESFETs are thus promising devices for use in high-speed and low-noise integrated circuits.
K2 yellow-band and Rb2 orange-band excimer emissions by electron-beam excitation
Authors: Xing Da , Ueda Ken-ichi , Takuma Hiroshi
Published: July 2002

Amplified spontaneous emissions of the K2 yellow and Rb2 orange diffuse bands were observed from e-beam-excited mixtures of K/K2 or Rb/Rb2 vapor with argon buffer gas. The continuum spectra centered at 574 and 604 nm were attributed to triplet-triplet K2 and Rb2 23Πg→13Σu+ bound-free transitions, respectively. The dissociative recombination of K3+ or Rb3+ is discussed as an efficient formation process of upper states by electron-beam pumping.
Studies of carrier heating in InGaAs/AlGaAs strained-layer quantum well diode lasers using a multiple wavelength pump probe technique
Authors: Sun C.-K. , Choi H. K. , Wang C. A. , Fujimoto J. G.
Published: July 2002

Carrier heating processes in InGaAs/AlGaAs strained-layer single-quantum well devices are studied by using a new femtosecond multiple-wavelength pump probe technique. Contributions from free-carrier absorption and stimulated transitions have been separated by using different combinations of pump and probe wavelengths above and below the band gap. Different cooling times were measured which reflect different thermalization mechanisms. Results show that free-carrier absorption is not always the dominant carrier heating process in III-V quantum well devices.
All-electronic generation of 880 fs, 3.5 V shockwaves and their application to a 3 THz free-space signal generation system
Authors: Van Der Weide D. W. , Bostak J. S. , Auld B. A. , Bloom D. M.
Published: July 2002

We report the first subpicosecond shockwaves ever generated and measured by entirely electronic means. These shockwaves have 880 fs fall times with 3.5 V amplitudes. This was accomplished at T=77 K with a monolithic nonlinear transmission line and diode sampling bridge fabricated on GaAs. We have used these circuits with integrated antennas to generate freely propagating pulses and have detected measurable radiation beyond 3 THz.
Pulsed laser deposition of thin metallic alloys
Authors: Krebs Hans-Ulrich , Bremert Olaf
Published: July 2002

The pulsed KrF excimer laser ablation was applied for the preparation of thin metallic alloys. Above an ablation threshold of about 5 J/cm2, an explosive evaporation of the target material occurs leading to high deposition rates of up to 3 nm/s and a stoichiometry transfer between the target and the deposited film. The surfaces of the grown amorphous and polycrystalline films are smooth except for a small number of droplets. The pulsed laser ablation was found to be an attractive alternative to other film deposition techniques, not only for high-temperature superconductors, semiconductors, and insulators, but also for metallic alloys.
Electrical characteristics of a stacked nitride/microcrystalline-silicon/oxide/silicon structure
Authors: Wu Shye Lin , Lee Chung Len , Lei Tan Fu
Published: July 2002

This letter reports a stacked nitride/microcrystalline-silicon/oxide/silicon structure, which exhibits a higher electron injection efficiency, a less electron trapping rate, and a larger charge to breakdown than the normal oxide. Besides, the room-temperature resonant tunneling effect is also observed for this structure.
Pure linear polarization imaging in near field scanning optical microscopy
Authors: Vaez-Iravani M. , Toledo-Crow R.
Published: July 2002

The design and theory of operation of a new form of near field polarizing optical microscope are presented. The system uses electro-optic premodulation of light to generate two simultaneous complementary images of samples. This affords the capability to obtain a final output signal which is a linear representation of the sample birefringence, and is independent of the sample transmissivity/reflectivity. A number of images are presented.
Absorption spectroscopic measurement of atomic density in laser-induced vapor plume
Authors: Duffey T. P. , McNeela T. G. , Mazumder J. , Schawlow A. L.
Published: July 2002

Laser absorption spectroscopy employing a tunable continuous wave dye laser has been used to measure the density of atomic niobium vapor in a laser ablation plume near the target surface. Population densities for one atomic level were measured to be ∼2×1015 cm−3 near the center of the plume.
Control of emission characteristics in organic thin-film electroluminescent diodes using an optical-microcavity structure
Authors: Takada Noriyuki , Tsutsui Tetsuo , Saito Shogo
Published: July 2002

An electroluminescent diode with a microcavity structure which comprised a reflective Ag anode (36 nm), a hole transport dye layer (250 nm), an emission dye laser (15 nm), an electron transport dye layer (240 nm), and a reflective MgAg cathode was fabricated. A diode without the microcavity structure with a transparent ITO anode was also prepared for reference. The diode with microcavity was driven in the electric excitation mode and emission spectra at fixed detection angles were measured together with the angular dependence of emission intensity at fixed wavelengths. A sharpening of emission spectra and a marked alteration of emission patterns in the diode with microcavity were observed.
Absence of solute drag in solidification
Authors: Kittl J. A. , Aziz M. J. , Brunco D. P. , Thompson M. O.
Published: July 2002

The interface response functions for alloy solidification were measured in the nondegenerate regime of partial solute trapping. We used a new technique to measure temperatures and velocities simultaneously during rapid solidification of Si-As alloys induced by pulsed laser melting. In addition, partition coefficients were determined using Rutherford backscattering. The results are in good agreement with predictions of the Continuous Growth Model without solute drag of M. J. Aziz and T. Kaplan [Acta Metall. 36, 1335 (1988)] and are inconsistent with all solute drag models.
Influence of cap layer thickness on optical quality in In0.2Ga0.8As/GaAs single quantum wells
Authors: Wang S. M. , Thordson J. V. , Andersson T. G. , Jiang S. , Yang L. X. , Shen S. C.
Published: July 2002

Influences of GaAs cap layer thickness on residual strain in partially relaxed, 25-nm-thick In0.2Ga0.8As/GaAs single quantum wells have been investigated by photoluminescence and photoreflectance at 77 K. It was found that the residual strain increased and the optical quality improved with increasing cap layer thickness. Therefore, both quantum well and cap layer thicknesses determine the optical quality in lattice-mismatched semiconductor heterostructures.
Molecular beam epitaxial growth of high quality InSb
Authors: Michel E. , Singh G. , Slivken S. , Besikci C. , Bove P. , Ferguson I. , Razeghi M.
Published: July 2002

In this letter we report on the growth of high quality InSb by molecular beam epitaxy that has been optimized using reflection high energy electron diffraction. A 4.8 μm InSb layer grown on GaAs at a growth temperature of 395 °C and a III/V incorporation ratio of 1:1.2 had an x-ray rocking curve of 158 arcsec and a Hall mobility of 92 300 cm2 V−1 at 77 K. This is the best material quality obtained for InSb nucleated directly onto GaAs reported to date.
A diode-pumped nonlinear mirror mode-locked Nd:YAG laser
Authors: Cerullo G. , Danailov M. B. , De Silvestri S. , Laporta P. , Magni V. , Segala D. , Taccheo S.
Published: July 2002

We report on passive mode-locking of a cw diode-pumped Nd:YAG laser using the nonlinear mirror technique. The nonlinear mirror is made by a lithium triborate frequency doubling crystal and a dichroic mirror that partially transmits the fundamental frequency and totally reflects the second harmonic. The laser produces nearly transform-limited pulses of 10 ps duration and 700 mW average power, with a slope efficiency of 28%. The mode-locking is self-starting under optimized conditions. Long term stability requires accurate control of the crystal temperature.
Infrared detector system for polarized single-crystal absorption spectra with a microspectrophotometer
Authors: Zelano John A. , Sigountos James G. , Makinen Marvin W. , Sanders Harold
Published: July 2002

A near-infrared, double-beam, light detection system is described for use with a microspectrophotometer in polarized absorption spectroscopic studies of single crystals. The appartus employs a modulated light source and exhibits high sensitivity with good stability. Its application to a variety of spectroscopic problems has provided accurate spectral recordings with a wide range of linearity in response.
Opposed coil magnet calculations for large sample and unilateral nuclear-magnetic resonance
Authors: Rath Alan R. , Roeder Stephen B. W. , Fukushima Eiichi
Published: July 2002

A magnet configuration has been devised, consisting of two nested coaxial coils with the current in the inner coil circulating in an opposite sense from that in the outer coil. The magnetic field generated by such an opposed pair exhibits a small region of homogeneity outside of the magnet itself, creating the possibility of constructing a unilateral nuclear-magnetic-resonance device capable of examining an object from only one side. Calculations on one special case, the inside-out Helmholtz configuration, indicate a volume of 10 cm3 with homogeneity of ±1% for a coil of outer radius 10 cm, and 0.1 cm3 with 100-ppm homogeneity. A second special case, consisting of two sets of opposed solenoids arranged in a quasi-Helmholtz manner, offers homogeneity comparable to a conventional Helmholtz pair of similar diameter but with an increase in separation of as much as a factor of 2.
Arbitrary waveform generator for turbulence experiments
Authors: Tsunoda S. I. , Malmberg J. H.
Published: July 2002

We have built a computer-controlled high-speed arbitrary waveform generator which has a bandwidth of 50 MHz. High-speed arbitrary waveform generators have a wide variety of possible applications. We built our waveform generator in order to produce repetitive, synthesized ‘‘noise’’ which can have any kind of statistical properties we desire. We have found this device to be quite useful in studying nonlinear mode coupling effects which occur when a weak warm beam interacts with waves on a slow wave structure.
Method for the preparation of dielectric films by activated reactive evaporation using resistively heated sources
Authors: George Joy , Pradeep B. , Joseph K. S.
Published: July 2002

A simple method is reported for the deposition of dielectric films using activated reactive evaporation (ARE). This method uses heated tungsten wire as an electron emitter and does not require a magnetic field for stabilizing the plasma, as required in an earlier reported method. The reactive gas pressure during coating is 5×10−4 Torr. An x-ray diffractogram and optical transmission spectra of Bi2O3 films deposited at a rate ≊50 Å/s using this apparatus are also presented.
Rectangular waveguide calorimeter for single intense microwave pulses
Authors: Earley L. M. , Ballard W. P. , Roose L. D.
Published: July 2002

A new calorimeter for single intense microwave pulses has been designed and tested. The device was constructed in WR284 rectangular waveguide and was operated at frequencies from 2.5 to 4.3 GHz with a tunable instantaneous bandwidth of approximately 500 MHz. The calorimeter used a single thermistor to measure the energy deposited on a carbon absorber having a microwave power absorbance of 90%. The calorimeter was tested at power levels from 100 to 1000 MW for pulse lengths of 12–6 ns, respectively. The sensitivity of the device was 200–300 mV/J.
Ion optics study in a single-beamlet system for the 160-keV Joint European Torus neutral beam injectors
Authors: Bottiglioni F. , Bussac J. P. , Jequier F.
Published: July 2002

The optics of the 160-keV deuterium neutral beam injection for the Joint European Torus–plug-in neutral injector (JET-PINI) have been studied in a single beamlet, using the test stand ligne d’etudes d’optiques (LEO). The beamlet optical features, that is perveance-divergence relationships, beam profiles, and steering angle by aperture offset, have been measured. Computations have been compared with the experimental results obtained both in this monobeamlet experiment and in the multibeamlet system of the 160-keV PINI injector.
Automatic sample loader for LKB model 9000 mass spectrometer
Authors: Kath Gary S. , McKeel Walter J. , Smith Jack L. , Liesch Jerrold M.
Published: July 2002

An automatic sample loading system is designed for use with the LKB model 9000 mass spectrometer. The apparatus permits solid samples previously placed in glass vials to be automatically entered one by one into the jet separator of the mass spectrometer for analysis. An 8085 based microcomputer controls the movement of the sample into the vacuum, positions the sample in a heating zone for vaporization, initiates a number of mass scan measurements, dumps the sample when complete, and prompts the data system for the next sample. The apparatus can analyze up to 50 samples with no operator intervention.
Focusing of multiply charged energetic ions using solenoidal B and radial E lenses
Authors: Liu W. Z. , Stern R. , Becchetti F. D.
Published: July 2002

Several large-solid-angle devices for collecting, at a common focus, multiply charged heavy ions from nuclear reactions have been studied. These devices use axial magnetic fields (solenoids), radial electric fields (coaxial lenses), or a combination of these. Although each system has particular advantages and disadvantages, several designs appear promising for use as practical devices.
On-line, real-time alkali monitor for process stream analysis
Authors: Hensel J. P. , Goff D. R. , Logan R. G. , Pineault R. , Romanosky R. R. , Wachter J. K.
Published: July 2002

In order to acquire real-time transient alkali data on coal-derived gaseous fuel and combustion streams often at low ppb levels, an extractive, total (vapor and particle-bound) sodium and potassium monitor has been designed, constructed, and tested. This fiber-optic alkali monitor (FOAM) utilizes state-of-the-art fiber-optic light transfer, a novel light-filtering background correction method, and high sensitivity photodiode signal detection. The sample enters the monitor’s high-temperature flame, which supplies energy to both decompose and excite the sample. The flame then emits light at the characteristic wavelengths of sodium and potassium. The resulting emissions are transferred by the fiber-optic bundle to the detection system, where the signal is filtered, background corrected, and transferred to the data system. The FOAM has advantages over previous instrumentation in being rugged, portable, and compact. Laboratory testing of the FOAM has been completed. The FOAM was determined to be highly sensitive (mid-ppt detection limits) with a wide linear dynamic range (four orders of magnitude). The results of field monitoring of alkali levels in the exhaust stream of a pressurized combustor using the FOAM indicated that the monitor was capable of real-time, fast tracking of transient alkali behavior in a high-temperature/high-pressure process stream.
Scanning picosecond optical parametric source using potassium dihydrogen phosphate in the visible and near infrared
Authors: Anthon D. W. , Nathel H. , Guthals D. M. , Clark J. H.
Published: July 2002

An optical parametric source using angle-tuned type II potassium dihydrogen phosphate (KDP) as the nonlinear medium and pumped with 35-ps, 355-nm pulses from an active–passive mode-locked Nd:YAG laser, is described. With a 1.35-mJ pump pulse, conversion efficiencies ranging from 1%–40% in the spectral range 450–650 and 800–1600 nm have been achieved. The ΔνΔt products can approach the transform limit, although 15–30 times transform limited is more typical. The merits of the combination of pump wavelength and phase match used here are discussed with respect to the tuning range, spectral width, and ease of operation. Automated scanning was achieved by placing the crystals on stepper-motor controlled rotation stages. A convenient, easily reproducible high peak power source rapidly tunable over much of the visible and near infrared is obtained.
Pulsed chemical HF laser using graphite continuous electrodes for transverse discharge stabilization
Authors: Raffo C. A. , Mosquera C. F. , Sorichetti P. A.
Published: July 2002

We report results obtained in the operation of a chemical HF laser using a mixture of SF6 and technical grade C3H8 reacting in a transverse high-voltage discharge in which a pair of inexpensive continuous electrodes of polycrystalline graphite are used as the only means for stabilizing the discharge and avoiding the formation of arcs during excitation of the laser medium. Energies of up to 60 mJ per pulse in stable operation are obtained from a 0.1-ℓ volume.
Improved LEED system using position-sensitive detection
Authors: Malic R. A.
Published: July 2002

An improved low-energy electron diffraction (LEED) system using a two-dimensional position-sensitive detector is described. The system is capable of storing LEED patterns at a resolution of 256×256 channels with up to 216 counts per channel. The maximum electron count rate is 100 kHz. A new position computer with edge-gating controls and a special event-counting memory interfaced to a personal computer is used to record the LEED intensities.
Simple x-ray alignment monitor
Authors: Steinmeyer P. A.
Published: July 2002

A simple x-ray alignment monitor having greater sensitivity than a hand-held fluorescent screen has been built and tested. The monitor is useful for alignment of diffractometers and powder cameras. The device is small, lightweight, rugged, and does not require a high-voltage power supply.
Transport properties of a silicon single-electron transistor at 4.2 K
Authors: Matsuoka Hideyuki , Kimura Shin’ichiro
Published: July 2002

We report on the transport properties of a silicon single-electron transistor at 4.2 K. A quantum dot is formed in the inversion layer of a silicon metal-oxide-semiconductor field-effect transistor with a dual-gate structure by introducing controllable tunnel barriers in the narrow channel. Periodic current oscillations due to the single-electron charging effect have been observed. Furthermore, current in the Coulomb blackade regime is explained by the inelastic cotunneling theory at finite temperatures.
Computer-controlled piezoresistance data-acquisition system
Authors: Amin Ahmed
Published: July 2002

A system for measuring the longitudinal and transverse piezoresistance matrix coefficients as a function of temperature is described. It utilizes a four-point probe for generating uniform tension-compression stresses in the test sample. For thin- and thick-film structures, the substrate elastic compliance s11 must be known to determine the elastroresistance matrix elements. Data acquisition and reduction are performed under full computer control. System architecture, capabilities, and examples of its output relevant to sensor design will be given.
Comment on ‘‘Optical carriage for laser-induced fluorescence in a magnetized plasma’’ [Rev. Sci. Instrum. 5
9, 2306 (1988)]
Authors: Goeckner M. J. , Goree J.
Published: July 2002

Anderegg et al. use a multimode optical fiber to transport their laser beam to a plasma for laser-induced fluorescence (LIF) experiments. While this method of laser light transportation is convenient, it is not suitable for all experiments. Experimenters considering using a multimode fiber should be aware of two undesirable complications that result from interference between various guided modes. First, for the measurement of the Doppler broadened line shapes, interference patterns may introduce undesirable inhomogeneous saturation line broadening. Second, for broadband ion density measurements, bending the fiber varies the interference pattern which alters the effective observed volume yielding unpredictable changes in the measured signal strength, particularly when the experiment requires high spatial resolution.
Comment on ‘‘VISAR analysis in the presence of large intensity changes: Application to the expanding ring’’ [Rev. Sci. Instrum. 6
0, 754 (1989)]
Authors: Hemsing Willard
Published: July 2002

A published method to salvage VISAR data that is imperfect, due to variations of light intensity, is necessary only when the instrument has not been properly set up. Normally corrections for changing intensity are made automatically.
Photoconductive properties of chemical vapor deposited diamond switch under high electric field strength
Authors: Yoneda Hitoki , Ueda Ken-ichi , Aikawa Yumi , Baba Kazuhiro , Shohata Nobuaki
Published: July 2002

Photoconductive properties of diamond optical switch made by chemical vapor deposition method were investigated. A new configuration of the diamond gap was proposed to reduce the surface leakage current and avoid surface flashover. This technology made it possible to apply static high electric field up to 2×106 V/cm. The dependence of the mobility-lifetime product (μτ) on the grain size was measured for a wide range of electric field. The μτ value was increased to be linearly proportional to the electric field for every grain size sample, and no saturation was measured even at a high electric field of E=3×105 V/cm. Larger grain size samples had larger μτ values. The grain size dependence was attributed to the decreasing of the mobility or the lifetime inside the grain not due to the increasing recombination ratio at the grain boundary in smaller grain size samples.
Magnetically suspended centrifuge for studies of nonlinear phenomena in stratified fluids: Developmental aspects
Authors: Gillies G. T. , Lawson M. A. , Ritter R. C. , Lawkins W. F. , Thompson S. , Sartory W. K.
Published: July 2002

Design studies of a novel magnetically suspended centrifuge suggest that such a device would be useful for investigating the nonlinear dynamics of interfacial waves in a rotating two-phase liquid. In its final form, the apparatus would use magnetic bearings, a directly-driven rotor, precision temperature control, and vibration isolation. The mechanical noise in the magnetic suspension coil of a preliminary apparatus was measured to be 3-μm rms in a 5-kHz bandwidth. However, these vibrations were attenuated by an active differentiator to the point where there was no observable oscillation in a 183-gram suspended test mass.
A high-sensitivity low-energy electron diffractometer
Authors: Jensen E. T. , Palmer R. E.
Published: July 2002

A high-sensitivity low-energy electron diffraction (LEED) system based on an electron energy loss spectrometer is described. This instrument is found to have the advantages of good angular resolution, very good energy resolution, low target current and high dynamic range. The experimental control and data collection are automated, which is found to be necessary to reduce measurement times to practicable levels. The performance of the system is illustrated by LEED data obained for a submonolayer of C6H6 physisorbed on graphite at 35 K where a weak diffraction feature is observed for the first time.
Electron-temperature determination in space plasmas with sounding-rocket electric field booms
Authors: Earle Gregory D.
Published: July 2002

The electron temperature can be determined from an interference signal that occurs in electric field data when the probe passes through the shadow of the vehicle. The technique does not perturb the surrounding plasma and is applicable to any sunlit sounding rocket or satellite experiment that measures the ambient electric field using high-impedance probes.
Simple measurement systems for permanent magnet quadrupole lenses
Authors: Okamoto H. , Iwashita Y. , Takekoshi H.
Published: July 2002

A simple and low-cost measurement system to determine the magnetized direction of a small piece of permanent magnet was devised. About 300 neodymium-iron-boron permanent magnets were measured by this system. Optimum combinations of these pieces were then determined for 30 eight-segmented permanent magnet quadrupole (PMQ) lenses. The PMQ bore field characteristics were measured by the rotating-coil method. An algorithm to determine the center position of the harmonic field with only one measurement is also presented in this article. The center position of the harmonic field evaluated with this algorithm agrees with the real center within an error of less than a few micrometers, and the measuring time was considerably reduced.