bluuebunny/crossref_metadata_2025 huggingface dataset:
Metallic contacts with individual Ru nanowires prepared by electrochemical deposition and the suppression of superconductivity in ultrasmall Ru grains
Authors: Wang H. , Wang J. , Tian M. , Bell L. , Hutchinson E. , Rosario M. M. , Liu Y. , Amma A. , Mallouk T.
Published: June 2004

Nanowires of Ru are a promising candidate for studying the intrinsic behavior of individual one-dimensional superconducting wires. We have prepared Ru nanowires by electrochemical deposition in porous polycarbonate membranes and characterized them structurally by high-resolution transmission electron microscopy and electron diffraction. Ru wires with diameters of 50 and 100nm were found to be polycrystalline, consisting of ultrasmall Ru grains with a typical size of 2nm. Metallic contacts to arrays of Ru nanowire as well as individual wires were made. Electrical transport measurements showed that these wires were metallic, but not superconducting down to 0.3K.
Excited state lifetime and intersystem crossing rate of asymmetric pentaazadentate porphyrin-like metal complexes
Authors: Byeon Clare C. , McKerns Michael M. , Sun Wenfang , Nordlund Thomas M. , Lawson Chris M. , Gray Gary M.
Published: June 2004

The first singlet excited state lifetimes (τs) of asymmetric pentaazadentate porphyrin-like complexes, [(R-APPC)M]Cln, were measured by the time-correlated single photon counting method. Fluorescent decays of the first singlet excited state for all [(R-APPC)M]Cln were found to be shorter than 0.5ns. The intersystem crossing rates (kisc) were calculated from the τs values and previously measured triplet quantum yields (ϕT). Values for kisc for the complexes ranged from 0.68 to 3.04×109s−1 and are significantly greater than those of silicon naphthalocyanine (SiNc) and lead phthalocyanine (PbPc(CP)4). The values of τs and kisc of the [(R-APPC)M]Cln complexes are sensitive to variations in both the bridging R group and the metal center.
Atomic force microscopy measurements of crystal nucleation and growth rates in thin films of amorphous Te alloys
Authors: Kalb J. , Spaepen F. , Wuttig M.
Published: June 2004

Ex situ atomic force microscopy in combination with a high-precision furnace has been employed for a systematic study of crystallization kinetics of sputtered amorphous Ag0.055In0.065Sb0.59Te0.29, Ge4Sb1Te5, and Ge2Sb2Te5 thin films used for optical data storage. Direct observation of crystals enabled us to establish the temperature dependence of the crystal nucleation rate and crystal growth velocity around 150°C. While these alloys exhibited similar crystal growth characteristics, the crystal nucleation behavior of Ag0.055In0.065Sb0.59Te0.29 differed significantly from that of Ge4Sb1Te5 and Ge2Sb2Te5. These observations provide an explanation for the different recrystallization mechanisms observed upon laser heating of amorphous marks.
Depth profiling of polycrystalline multilayers using aBuckminsterfullerene projectile
Authors: Sun S. , Wucher A. , Szakal C. , Winograd N.
Published: June 2004

Depth resolution of 5nm was achieved on a Ni:Cr multilayer structure using 15keV C60+ ion bombardment for depth profiling. The results, acquired by monitoring the sputtered neutral flux of Ni and Cr atoms, are of equivalent quality to those achieved using low-energy obliquely incident atomic beams with sample rotation. The reason behind these improved results is shown to be due to the unique ability of this cluster ion to remove material without regard to crystallographic orientation, hence reducing the buildup of topography.
Oscillating growth of surface roughness in multilayer films
Authors: Liu Z.-J. , Shen Y. G.
Published: June 2004

The surface and interface growth of binary multilayer films has been studied using nonlinear continuum theory. Numerical simulations show that the surface roughness of a multilayer film experiences an oscillating growth, with smoothing of the interface roughness existing at one type of interface and growth-induced roughening observed at another type of interface. Such interface smoothing and roughening effects are apparently related to the growth time of individual thin layers and consequently to the bilayer thickness. In particular, the change in the thickness ratio between adjacent layers shows a marked effect on the interface roughness. Our simulations also reveal that despite the existence of such an oscillating growth feature the surface roughness of a multilayer film almost exhibits an exponential dependence on the growth time and the scaling law found in the growth of single-layer films is also valid for multilayers.
Photon band gap properties and omnidirectional reflectance in Si∕SiO2 Thue–Morse quasicrystals
Authors: Dal Negro L. , Stolfi M. , Yi Y. , Michel J. , Duan X. , Kimerling L. C. , LeBlanc J. , Haavisto J.
Published: June 2004

Aperiodic one-dimensional Si∕SiO2 Thue–Morse (T–M) multilayer structures have been fabricated in order to investigate both the band gap properties with respect to the system size (band gap scaling) and the omnidirectional reflectance at the fundamental optical band gap. Variable angle reflectance data have experimentally demonstrated a large reflectance band gap in the optical spectrum of a T–M quasicrystal, in agreement with transfer matrix simulations. We explain the physical origin of the T–M omnidirectional band gap as a result of periodic spatial correlations in the complex T–M structure. The unprecedented degree of structural flexibility of T–M systems can provide an attractive alternative to photonic crystals for the fabrication of photonic devices.
Ultrafast response of photonic crystal atoms with Kerr nonlinearity to ultrashort optical pulses
Authors: Lan Sheng , Gopal Achanta Venu , Kanamoto Kyozo , Ishikawa Hiroshi
Published: June 2004

We investigate the response of photonic crystal (PC) atoms with Kerr nonlinearity to the excitation of ultrashort optical pulses. Surprisingly, it is found that PC atoms with sharp resonant peaks in frequency spectrum (or with large quality factors) can respond to ultrashort pulses very rapidly when Kerr nonlinearity is introduced. More interestingly, the response time under high-power densities can be even shorter than the duration of the pump pulse. It is revealed that the nonlinearity induced broadening of dynamical frequency spectrum is responsible for the ultrafast response time, implying the possibility of ultrafast all-optical switching.
Highly nondegenerate four-wave mixing in a tunable dual-mode semiconductor laser
Authors: Park Icksoon , Fischer Ingo , Elsäßer Wolfgang
Published: June 2004

We present experimental investigations of highly nondegenerate four-wave mixing in a tunable dual-mode semiconductor laser. The fundamental interacting waves are two lasing modes selected in an external double Littman–Metcalf cavity configuration. We investigate the conversion efficiency depending on the detuning frequencies up to 1.2THz. We find that the newly generated waves are significantly enhanced due to the cavity resonances. Our investigations allow us to characterize and understand the dynamics of the simultaneous dual-mode operation in the semiconductor laser, which is attractive for the generation of continuous-wave THz radiation by photomixing.
Validation of a new spectrometer for noninvasive measurement of cardiac output
Authors: Baum Marc M. , Kumar Sasi , Moss John A. , Wagner Peter D.
Published: June 2004

Acetylene is a blood-soluble gas and for many years its uptake rate during rebreathing tests has been used to calculate the flow rate of blood through the lungs (normally equal to cardiac output) as well as the volume of lung tissue. A new, portable, noninvasive instrument for cardiac output determination using the acetylene uptake method is described. The analyzer relies on nondispersive IR absorption spectroscopy as its principle of operation and is configured for extractive (side-stream) sampling. The instrument affords exceptionally fast (30 ms, 10%–90%, 90%–10%, at 500 mL min−1 flow rates), interference-free, simultaneous measurement of acetylene, sulfur hexafluoride (an insoluble reference gas used in the cardiac output calculation), and carbon dioxide (to determine alveolar ventilation), with good (typically ±2% full-scale) signal-to-noise ratios. Comparison tests with a mass spectrometer using serially diluted calibration gas samples gave excellent (R2>0.99) correlation for all three gases, validating the IR system’s linearity and accuracy. A similar level of agreement between the devices also was observed during human subject C2H2 uptake tests (at rest and under incremental levels of exercise), with the instruments sampling a common extracted gas stream. Cardiac output measurements by both instruments were statistically equivalent from rest to 90% of maximal oxygen consumption; the physiological validity of the measurements was confirmed by the expected linear relationship between cardiac output and oxygen consumption, with both the slope and intercept in the published range. These results indicate that the portable, low-cost, rugged prototype analyzer discussed here is suitable for measuring cardiac output noninvasively in a point-of-care setting.
Characterization of a wavelength-tunable surface plasmon resonance microscope
Authors: Fu Elain , Chinowsky Timothy , Foley Jennifer , Weinstein Joshua , Yager Paul
Published: June 2004

We have built and characterized the operation and performance of a surface plasmon resonance microscope that uses the rotation of an interference filter to vary the imaging wavelength of the system. The operation of the microscope with respect to signal processing, the dynamic range, and the limit of detection of the system, are described.
Parallel-detection microwave spectroscopy system for breast imaging
Authors: Li Dun , Meaney Paul M. , Raynolds Timothy , Pendergrass Sarah A. , Fanning Margaret W. , Paulsen Keith D.
Published: June 2004

A liquid-coupled, noncontacting, broadband microwave imaging system has been designed and fabricated. Extension of the operating bandwidth allows us to exploit the potential of new clinical information for breast cancer diagnosis at frequencies higher than previously achieved. The new system design implements a parallel-detection scheme that allows signals to be simultaneously sampled at multiple receiving antenna sites (in 8 s for a single tomographic slice at a single frequency). It also has important features such as high cross-channel isolation (>120 dB), smooth broad bandwidth receiver response, and adjustable intermediate frequency signal amplification factors of 1 to 2000 to ensure successful realization of a large linear dynamic range which is especially important to counteract the increased signal loss at the higher operating frequencies. The new system is capable of recovering dielectric properties of breastlike phantoms with tumor inclusions over the frequency range from 0.5 to 2.1 GHz when embedded in an 87%/13% glycerin/water background. Errors in the measurement data are less than 0.5% in signal amplitude and 1° in phase, on average.
Prototype imaging x-ray fluorescence spectrometer based on microchannel plate optics
Authors: Price G. J. , Fraser G. W. , Pearson J. F. , Nussey J. P. , Hutchinson I. B. , Holland A. D. , Turner K. , Pullan D.
Published: June 2004

A new form of imaging x-ray fluorescence spectrometer, based on a microchannel plate relay optic and a charge coupled device x-ray detector, produces elemental mapping over an instantaneous field of view of 24 mm square without the need to scan either the sample or x-ray beam. We describe the design of a prototype responsive over the energy range of 370 eV–10 keV, its quantitative calibration, demonstration of 0.7 mm spatial resolution and the spectrometer’s use in the analysis of geological samples.
Laser-assisted three-dimensional rotation of microscopic objects
Authors: Mohanty Samarendra K. , Gupta Pradeep K.
Published: June 2004

We describe an approach for laser-assisted three-dimensional rotation of microscopic objects that is rather simple to implement. In our approach a tangential force is applied on the object to cause its rotation by focusing a pulsed near infrared laser beam at a point on the periphery of the object. Rotation of a leaf tissue section in three dimensions about various axes including those orthogonal to the beam propagation axis could be demonstrated using this approach. Further, with this approach an optically trapped dividing chloroplast could be oriented to permit imaging from different angles of view.
Compact autocorrelator for the online measurement of tunable 10 femtosecond pulses
Authors: Kozma I. Z. , Baum P. , Schmidhammer U. , Lochbrunner S. , Riedle E.
Published: June 2004

An optical pulse autocorrelator is described which allows online measurement of femtosecond pulse profiles of tunable light sources having 100 Hz–10 kHz repetition rates. The device is capable of dispersion-free noninterferometric measurement of pulse durations ranging from about 100 to sub-10 fs. The applicability of the device is demonstrated in the wavelength range from 420 to 1460 nm. The time delay is scanned with a simple open-loop piezoceramic translator, which is interferometrically calibrated. The accuracy of the device is verified by comparing an autocorrelation trace of a 10 fs pulse with the autocorrelation computed from a zero-additional-phase-spectral phase interferometry for direct electric field reconstruction (ZAP-SPIDER) measurement in the visible region. Its compact design and high sensitivity make the autocorrelator an ideal tool for the diagnostics of tunable ultrashort pulses.
Flash A/D converter based on Vernier caliper design
Authors: Huang C. F. , Huang S. S. , Fu I.-Yung
Published: June 2004

This study presents a method for the design of an N−bit flash analog-to-digital (A/D) converter which employs the main-scale Vernier-scale characteristics of a Vernier caliper. The proposed design is similar to a half flash design where the main half flash A/D converts the N/2 most significant bits (MSBs) from comparisons of the input signal with all of the quantization thresholds, while the Vernier (scale) half flash A/D converts the N/2 least significant bits (LSBs). Relative to previous designs, this architecture reduces the number of comparators while maintaining high resolution and speed. A 12 bit prototype is tested by code density analysis, showing integral nonlinearity within ±1.0 LSB and differential nonlinearity within ±0.5 LSB. Resolution is strongly dependent on precision current sources and resistor ladders, and analog switch ON resistance must be far less than resistor ladder resistance. Such requirements, however, are easily met with very-large-scale integrated technologies, making the Vernier flash A/D converter a good candidate for high-performance, low-cost, low-power flash A/D converter designs.
Layering of ultrathin SiO2 film and study of its growth kinetics
Authors: Gayathri N. , Banerjee S.
Published: June 2004

A systematic kinetic study of SiO2 thin film thermally grown on Si(100) substrate by a single step and two step dry oxidation process is presented. Films grown at lower temperature (750°C) show higher density than films grown at higher temperature (1000°C). If the oxidation is carried out in two steps i.e., the first oxidation step at a lower temperature (750°C) and the second one at a higher temperature (1000°C), two distinct layers of SiO2 having different densities can be obtained. The film density was measured using the grazing incidence x-ray reflectivity technique. We also observed that when the thickness of the first “top” layer increases the growth of the “bottom” layer is retarded leading to lowering of total thickness of the SiO2 film even though the total oxidation time is increased.
Binary superlattice quantum-well infrared photodetectors for long-wavelength broadband detection
Authors: Ellis A. R. , Majumdar Amlan , Choi K. K. , Reno J. L. , Tsui D. C.
Published: June 2004

We have adopted a binary superlattice structure for long-wavelength broadband detection. In this superlattice, the basis contains two unequal wells, with which more energy states are created for broadband absorption. At the same time, responsivity is more uniform within the detection band because of mixing of wave functions from the two wells. This uniform line shape is particularly suitable for spectroscopy applications. The detector is designed to cover the entire 8–14μm long-wavelength atmospheric window. The observed spectral widths are 5.2 and 5.6μm for two nominally identical wafers. The photoresponse spectra from both wafers are nearly unchanged over a wide range of operating bias and temperature. The background-limited temperature is 50K at 2V bias for F∕1.2 optics.
High temperature high-dose implantation of aluminum in 4H-SiC
Authors: Saks N. S. , Suvorov A. V. , Capell D. C.
Published: June 2004

Heavily doped p-type layers obtained by implanting aluminum near its solubility limit (∼2×1020Al∕cm3) in 4H-SiC are characterized as a function of the implant and anneal temperatures. For a typical implant temperature of 650°C, Al activation rates of ∼6%–35% are obtained for anneals from 1600 to 1750°C, respectively. For higher temperature implants at 1000°C, the Al activation rates are significantly improved, approaching ∼100% for the same anneal temperatures, with a best p-type resistivity of ∼0.20Ωcm. For SiC device fabrication, these results demonstrate that by using higher Al implant temperatures, lower anneal temperatures can be used while obtaining close to 100% Al activation.
Zn
0.9
Co
0.1
O
-based diluted magnetic semiconducting thin films
Authors: Ramachandran S. , Tiwari Ashutosh , Narayan J.
Published: June 2004

Here we report a systematic study of structural, optical, and magnetic measurements on epitaxial Zn0.9Co0.1O films grown on c-plane sapphire single crystal, at various temperatures (500–650°C), using pulsed-laser deposition. The main emphasis in this work has been on the correlation of microstructure with properties, specifically with magnetic properties and the fate of cobalt ions into substitutional sites versus precipitates. The reasons for room-temperature ferromagnetism are explored, and convincingly proved to be one of the inherent properties of the material. Most importantly, the presence of nanoclusters of any magnetic phase was ruled out. This was determined by high-resolution transmission electron microscopy, coupled with electron energy loss spectroscopy and STEM-Z (scanning transmission electron microscopy-atomic number) contrast studies.
Improved Pt∕Au and W∕Pt∕Au Schottky contacts on n-type ZnO using ozone cleaning
Authors: Ip K. , Gila B. P. , Onstine A. H. , Lambers E. S. , Heo Y. W. , Baik K. H. , Norton D. P. , Pearton S. J. , Kim S. , LaRoche J. R , Ren F.
Published: June 2004

UV-ozone cleaning prior to metal deposition of either e-beam Pt contacts or sputtered W contacts on n-type single-crystal ZnO is found to significantly improve their rectifying characteristics. Pt contacts deposited directly on the as-received ZnO surface are Ohmic but show rectifying behavior with ozone cleaning. The Schottky barrier height of these Pt contacts was 0.70eV, with ideality factor of 1.5 and a saturation current density of 6.2×10−6Acm−2. In contrast, the as-deposited W contacts are Ohmic, independent of the use of ozone cleaning. Postdeposition annealing at 700°C produces rectifying behavior with Schottky barrier heights of 0.45eV for control samples and 0.49eV for those cleaned with ozone exposure. The improvement in rectifying properties of both the Pt and W contacts is related to removal of surface carbon contamination from the ZnO.
Effects of capillary forces on copper∕dielectric interfacial void evolution
Authors: Choy Jun-Ho , Kavanagh Karen L.
Published: June 2004

The shape evolution of interface voids in copper metallization systems under electromigration stress is modeled including instabilities driven by both capillary and electron wind forces. The model employs a three-dimensional, axisymmetric, finite-difference method combined with a boundary-element electrical potential. With zero electric field or with small fields applied, a large void experiences a capillary instability which leads to open circuit failure. As the electric field becomes larger, the growth of this instability is suppressed and the void shape stabilizes. Thus, for a typical electromigration stress condition, a large copper void elongates its shape along the interface parallel to the electric field, suggesting a mechanism for the delayed open circuit failure observed in copper integrated circuit metallization system.
Influence of surface steps on glide of threading dislocations during layer growth
Authors: Hoagland R. G. , Hirth J. P. , Misra A. , Mitlin D.
Published: June 2004

We discuss the relaxation of coherency stresses by glide of threading dislocations in a layer that is growing coherently on a substrate. Glide of threading dislocations becomes energetically favorable when the thickness of the layer exceeds a critical value, hc. Predicted values of hc are often less than indicated by experimental observations. We show that the energy associated with the creation or removal of steps on the surface of a growing layer is important in determining the hc associated with glide of threading dislocations.
Origin and applications of magnetically tunable refractive indexof magnetic fluid films
Authors: Yang S. Y. , Chieh J. J. , Horng H. E. , Hong Chin-Yih , Yang H. C.
Published: June 2004

When an external field was applied, the refractive index of the magnetic fluid film was observed to be modulated as the field exceeded a critical strength. We found that the stronger the magnetic field, the higher the refractive index. By taking both the formation of the columns and the variation in the concentration of the liquid phase in magnetic fluid films under external magnetic fields into account, the refractive index was calculated and compared with experimental data. When we did this, we noticed a consistency that implies that the phase separation leads to the variation in the refractive index of the magnetic fluid film as the magnetic field strength is changed. With such a property as a tunable refractive index, the feasibility of using a magnetic fluid in a tunable optical device is worthy of investigation.
Magnetoresistance and thermal stability enhancement in FeCr-based spin valves
Authors: Sbiaa Rachid , Morita Haruyuki
Published: June 2004

In a synthetic spin valve (SV), a thin FeCr layer inserted in the pinned layer closer to the antiferromagnetic layer was found to improve the magnetoresistance, the pinning field strength, and thermal stability. Single SVs with 1-nm-thick FeCr inserted in the pinned layer shows a magnetoresistance ratio (MR) of 18% and a pinned field of about 1700Oe. This letter reports on the high MR in an all-metal single SV without specular scattering using a nano-oxide layer or spin filtering. This result, suggests that FeCr with high resistance and low spin polarization is effective in increasing the spin scattering and maximize the contribution of the pinned layer closer to spacer on the magnetotransport while keeping its antiferromagnetic exchange coupling high. The FeCr thin layer may also have an effect on minimizing Mn diffusion into the pinned layer and spacer as revealed by the increase of the pinning field.
Transport properties of germanium-filled CoSb3
Authors: Nolas G. S. , Yang J. , Takizawa Hirotsugu
Published: June 2004

We report the transport properties of dense polycrystalline Ge filled skutterudites Ge0.25Co4Sb12 and Ge0.05Co4Sb12 perepared by a high-pressure synthesis approach. Low temperature electrical resistivity, Seebeck coefficient, Hall coefficient, and thermal conductivity measurements were performed and compared with those of Co4Sb11Ge and CoSb3. The Ge atoms residing inside the interstitial voids of the skutterudite crystal structure act as electron donors. The lattice thermal conductivity of these compounds is lower than that of CoSb3 but higher than that of other filled skutterudites. The potential for thermoelectric applications is also discussed.
Luminescence efficiency of InGaN multiple-quantum-well ultravioletlight-emitting diodes
Authors: Pan Chang-Chi , Lee Chia-Ming , Liu Jia-Wen , Chen Guan-Ting , Chyi Jen-Inn
Published: June 2004

The electroluminescence efficiency of In0.06Ga0.94N∕GaN multiple-quantum-well UV light-emitting diodes (LEDs) with emission wavelength of 400nm has been investigated and compared with blue (470nm) LEDs. Based on their injection current-dependent characteristics under dc and pulsed operation, it can be concluded that carrier overflow is the dominant factor that affects the external quantum efficiency of UVLED before thermal effects take over. It is experimentally shown that increasing the number of quantum wells is necessary to alleviate the carrier overflow issue and improve the luminescence efficiency of the UVLEDs.
Unique optical properties of AlGaN alloys and related ultraviolet emitters
Authors: Nam K. B. , Li J. , Nakarmi M. L. , Lin J. Y. , Jiang H. X.
Published: June 2004

Deep UV photoluminescence spectroscopy has been employed to study the optical properties of AlxGa1−xN alloys (0⩽x⩽1). The emission intensity with polarization of E⊥c and the degree of polarization were found to decrease with increasing x. This is a consequence of the fact that the dominant band edge emission in GaN (AlN) is with polarization of E⊥c(E∥c). Our experimental results suggest that the decreased emission efficiency in AlxGa1−xN alloys and related UV emitters could also be related with their unique polarization property, i.e., the intensity of light emission with polarization of E⊥c decreases with x. It is thus concluded that UV emitters with AlGaN alloys as active layers have very different properties from InGaN and other semiconductor emitters.
Stacking fault formation in SiC p-i-n diodes of (11-20) orientation
Authors: Ha S. , Hu K. , Skowronski M. , Sumakeris J. J. , Paisley M. J. , Das M. K.
Published: June 2004

Formation of stacking faults in 4H-SiC p-i-n diodes fabricated on a (11-20) oriented substrate was investigated using optical emission microscopy and transmission electron microscopy. The stacking faults developed and expanded in basal planes under forward bias with current densities between 1.0 and 100A∕cm2. Preexistent basal plane dislocations threading the blocking layer served as nucleation sites. Transmission electron microscopy identified the stacking faults as single-layer Shockley type. The stacking fault expansion in diodes on (11-20) wafers is inconsistent with substrate-induced biaxial stress as the driving force.
Generation of high-power-density atmospheric pressure plasma with liquid electrodes
Authors: Dong Lifang , Mao Zhiguo , Yin Zengqian , Ran Junxia
Published: June 2004

We present a method for generating atmospheric pressure plasma using a dielectric barrier discharge reactor with two liquid electrodes. Four distinct kinds of discharge, including stochastic filaments, regular square pattern, glow-like discharge, and Turing stripe pattern, are observed in argon with a flow rate of 9slm. The electrical and optical characteristics of the device are investigated. Results show that high-power-density atmospheric pressure plasma with high duty ratio in space and time can be obtained. The influence of wall charges on discharge power and duty ratio has been discussed.
Large-angle beam steering using all-optical liquid crystal spatial light modulators
Authors: Tabiryan N. V. , Nersisyan S. R.
Published: June 2004

We have demonstrated operation of an all-optical liquid crystal (spatial light modulator) used for steering a laser beam over large angles. Continuous steering over ±12.4° is achieved, controlled by the power of an infrared pump beam; This is a very large steering angle for a nonmechanical nondiffractive system.
Active junction isolation for smart power integrated circuits
Authors: Starke T. K. H. , Igic P. M. , Holland P. M. , Hussain S. , Jamal W. M. , Mawby P. A.
Published: June 2004

A structure for the isolation of power transistors from (CMOS) control circuitry used in smart power integrated circuits is proposed. This negative feedback activated junction isolation is compatible with standard CMOS technology.
Selective transport and mobility edges in quasi-one-dimensional systems with a stratified correlated disorder
Authors: Izrailev F. M. , Makarov N. M.
Published: June 2004

We present analytical results on transport properties of many-mode waveguides with randomly stratified disorder having long-range correlations. To describe such systems, the theory of one-dimensional transport recently developed for a correlated disorder is generalized. The propagation of waves through such waveguides may reveal a quite unexpected phenomena of a complete transparency for a subset of propagating modes. We found that with a proper choice of long-range correlations one can arrange a perfect transparency of waveguides inside a given frequency window of incoming waves. Thus, mobility edges are shown to be possible in quasi-one-dimensional geometry with correlated disorder. The results may be important for experimental realizations of a selective transport in application to both waveguides and electron∕optic nanodevices.
Ion implant dose dependence of photocarrier radiometry at multiple excitation wavelengths
Authors: Shaughnessy Derrick , Li Bincheng , Mandelis Andreas , Batista Jerias
Published: June 2004

The dependence of the photocarrier radiometric (PCR) signal on ion implant dose in Si is reported. The results show almost entirely monotonic behavior over a large range of industrially relevant fluences (1×1010–1×1016cm−2) for B+11, As+75, P+31, and BF2+ implanted in Si wafers at various energies. In addition, the use of excitation sources with a range of absorption coefficients is shown to be very useful in improving the sensitivity of the PCR amplitude to implant dose.
Exchange anisotropy of polycrystalline Mn–Ir∕Co–Fe bilayers enlarged by long-time annealing
Authors: Tsunoda Masakiyo , Sato Takashi , Hashimoto Takahiko , Takahashi Migaku
Published: June 2004

The effect of long-time annealing on the exchange anisotropy of polycrystalline Mn75Ir25 dAF∕Co70Fe304nm bilayers was investigated to induce large unidirectional anisotropy constant, JK, with very thin antiferromagnetic layer. As a notable result, extra large value of JK=0.87erg∕cm2 was obtained in the bilayer with dAF=5nm after 200h annealing at 250°C, which is larger than twice the maximum value of PtMn∕Co–Fe system usually used in spin valves of hard disk drives. According to the single spin ensemble model, the enlargement of JK by the long-time annealing is explained as a result of the change of the distribution of antiferromagnetic spin directions.
Controlling the site density of multiwall carbon nanotubes via growth conditions
Authors: Siegal M. P. , Overmyer D. L. , Kaatz F. H.
Published: June 2004

We present two complementary methods for controlling the site density of multiwall carbon nanotubes (CNTs) directly as a function of growth conditions from 1011to107CNTs∕cm2. Several potential applications require significant spacing between individual CNTs. The first method shows that the site density varies with the heat of formation of the hydrocarbon gas used during CNT growth by thermal chemical vapor deposition. The second method demonstrates that the site density decreases with increasing residual stress of the metal catalyst∕diffusion barrier layers. These methods are combined for wide-range control of CNT site density.
In
Ga
N
∕
Ga
N
single-quantum-well light-emitting diodes optical output efficiency dependence on the properties of the barrier layer separating the active and p-layer regions
Authors: Florescu D. I. , Ramer J. C. , Lee D. S. , Armour E. A.
Published: June 2004

We have examined the output optical efficiency dependence of InGaN∕GaN single-quantum-well (SQW) structures on the properties of the barrier layer separating the active and p-layer regions in typical metalorganic chemical vapor deposition grown light-emitting-diode (LED) devices. Based on room-temperature electroluminescence and 10–300K photoluminescence findings, the optical output of SQW LEDs was found to be extremely sensitive to narrow range variations in thickness, growth temperature, and surface roughness of the uppermost barrier layer in such devices. Applying these principles and observations, a thermally robust 465nm SQW LED with an unpackaged chip-level output power in the 5.0–6.0mW range and forward voltage <3.2V at 20mA has been achieved.
Novel instrument system for discriminating secondary particles in high-spatial-resolution neutron detection
Authors: Yamagishi H. , Nakamura T. , Soyama K. , Masaoka S. , Aizawa K.
Published: June 2004

A new instrument system with the capability of secondary-particle discrimination (InSPaD) was studied for the development of two-dimensional (2D) neutron detectors (NDs) filled with helium-3 gas and with high spatial resolution. The InSPaD can discriminate between tracks of a proton and a triton created in the nuclear reaction He3(n,p)T by simply setting the level of the discriminator appropriately in each signal channel, and the system exhibits a high spatial resolution, high counting rate, low background, and stability. The InSPaD identifies the tracks of a proton and a triton on the basis of the length of the tracks, identifies the secondary particles, and calculates the incident positions of neutrons accurately in real time. Simulations of the 2D ND equipped with InSPaD revealed spatial resolutions of 0.46 mm in full width at half maximum for a 10% mixture of C2H6 with helium-3 at 0.3 MPa, and of 0.52 mm for a 20% mixture of argon with helium-3 at 0.5 MPa. The simulated results of the ranges of secondary particles and the pulse-height distribution along the track agreed well with the experimental results of neutron detection using a microstrip gas chamber, thus indicating the feasibility of the InSPaD.
Foil chaff ejection systems for rocket-borne measurement of neutral winds in the mesosphere and lower thermosphere
Authors: Koizumi Yoshiko , Shimoyama Manabu , Oyama Koh-Ichiro , Murayama Yasuhiro , Tsuda Toshitaka , Nakamura Takuji
Published: June 2004

The foil chaff technique has been used on microrockets such as “Viper” for a long time to measure neutral winds with high altitude resolution in the mesosphere and lower thermosphere. We have developed two new foil chaff storage and ejection systems for muti-instrumented sounding rockets. The first system uses a spring loaded split cylinder which holds the foil chaff, housed in an outer cylinder. The shaft of the split cylinder is kept in place by a lock plate and a stainless steel wire. The split cylinder is ejected by cutting the wire. The second system is of differential pressure type. The cap of an airtight cylinder has a shaft and a sponge piece for sweeping out the foil chaff. The cylinder is sealed at ground level and at the desired height of release, the cap comes out due to differential pressure and brings out the foil chaff. Both these systems were successfully tested on a Japanese sounding rocket in January 2000, releasing about 20 000 pieces of foil chaff during the rocket’s descent. Neutral winds were measured in the height range of 85.5–95.0 km with a height resolution of 300 m.
Magneto-optical apparatus to measure ac magnetic susceptibility
Authors: del Real R. P. , Rosa G. , Guerrero H.
Published: June 2004

A new setup to measure magnetic susceptibility versus the temperature, based on magneto-optical transmission techniques, has been developed. The advantage with respect to conventional systems is that it allows measurements in a wider range of frequencies (0.1–105 Hz). It is thought it can be used with transparent magnetic samples. Due to the dependence of the output signal on the magneto-optical properties of the materials under test, these properties must be known to achieve calibration.
Measurement of the shear storage modulus and viscosity of liquids using the Bleustein–Gulyaev wave
Authors: Kiełczyński P. , Pajewski W. , Szalewski M. , Balcerzak A.
Published: June 2004

In the article, a method for measuring the rheological properties of viscoelastic liquids using the (surface shear) Bleustein–Gulyaev (B–G) wave is presented. By applying the perturbation method, one can prove that the change in the complex propagation constant of the B–G wave produced by the layer of viscoelastic liquid loading the waveguide surface is proportional to the shear acoustic impedance of the liquid. From the analysis performed by the authors, it results that the sensitivity of the B–G wave method used to determine the rheological parameters of the liquid is even higher than the sensitivity of the Love wave method. In this article, a practical measuring setup employing the B–G wave for the purpose of measuring the rheological properties of the liquid is presented. Subsequently, by measuring the change in the velocity and attenuation of the B–G wave, the shear impedance of the liquid was evaluated. Knowledge of the shear impedance of the investigated liquid then made it possible to calculate, for a given rheological model, the shear storage modulus μ and viscosity η of the investigated liquid. Measurements of liquid viscosity performed using the B–G wave method were compared to those obtained from the static capillary (Ubbelohde) method.
The biology and associations of Fergusobia (Nematoda) from the Melaleuca leucadendra-complex in eastern Australia
Authors: Davies Kerrie A. , Giblin-Davis Robin M.
Published: June 2004

Nematodes of the genus Fergusobia Currie (Tylenchida : Neotylenchidae) and flies of the genus Fergusonina Malloch (Diptera : Fergusoninidae) together form the only known mutualistic association between insects and nematodes that induces galls in young meristematic tissues in Myrtaceae. Six new species of Fergusobia are described (F. quinquenerviae, sp. nov., F. cajuputiae, sp. nov., F. dealbatae, sp. nov., F. leucadendrae, sp. nov., F.�nervosae, sp. nov., and F. viridiflorae, sp. nov.) and partial descriptions are presented for a further two species. Together, these taxa form a putative monophyletic group, apparently restricted to species of Melaleuca in the broad-leaved M. leucadendra-complex, from coastal Queensland and north-east New South Wales, Australia. Each species of nematode has a mutualistic association with a particular species of Fergusonina fly and (with one exception) each association is apparently restricted to one particular species of Melaleuca.
Strand exchange activity of human recombination protein Rad52
Authors: Kumar Jaspal K. , Gupta Ravindra C.
Published: June 2004

Repair of double-strand breaks is essential for the maintenance of genome integrity and cell survival. In eukaryotes, double-strand-break repair by homologous recombination requires the Rad52 group of proteins. Human Rad52 protein (HsRad52)-mediated annealing of complementary strands has been studied in detail, but little has been reported on the recombinase activities of HsRad52. For this study, we purified HsRad52 from
Escherichia coli
. DNase I protection experiments indicated that HsRad52 binds preferentially to single-stranded DNA and protects it against digestion by DNase I. HsRad52 catalyzed D-loop formation in superhelical DNA, as well as strand exchange among oligonucleotide substrates. The formation of a stoichiometric complex between HsRad52 and single-stranded DNA was found to be critical for strand exchange activity, and the coating of both the single- and double-stranded oligonucleotides inhibited the exchange reaction.
MICROBIC VIRULENCE AND HOST SUSCEPTIBILITY IN PARATYPHOID-ENTERITIDIS INFECTION OF WHITE MICE
Authors: Pritchett Ida W.
Published: June 2004

Epidemics of mouse typhoid set up among the Rockefeller Institute strain of mice were studied over a period of 6 months. During this time the relationship of cage number of mouse typhoid bacilli to mortality, total population, and survival time was determined. A single virulence titration of the epidemic strain was made, and at the end of the experiment all survivors were examined for evidence of infection. The following conclusions may be drawn for the data here presented.

1. The available dosage of mouse typhoid bacilli varied directly with the mortality (plus a time constant of 6 to 8 days) and inversely with the survival time.

2. The virulence of the epidemic strain appeared to be practically the same as that of the original stock culture.

3. About 53.5 per cent of the survivors of one epidemic and 68 per cent of those in the other showed, at the end of the experiment, no signs of infection; the others had either specific blood agglutinins, or living bacteria in their heart's blood, spleen, feces, or gall bladder.

4. During the course of the epidemic, the original infecting strain (mouse typhoid Type II—Bacillus pestis caviæ) was almost entirely replaced by an antigenically dissimilar strain (mouse typhoid Type I—Bacillus enteritidis), probably introduced through the inadvertent inclusion of fecal carriers among the normal mice added as contacts.
MICROBIC VIRULENCE AND HOST SUSCEPTIBILITY IN PARATYPHOID-ENTERITIDIS INFECTION OF WHITE MICE
Authors: Pritchett Ida W.
Published: June 2004

Four separate strains of mice have been tested for their relative susceptibility to per os infection with the Type II bacillus of mouse typhoid (Bacillus pestis caviæ), 300 to 600 individuals of each strain having been employed in the course of 12 months. In confirmation of a previous paper, clear-cut differences in the susceptibility of these strains have been shown to exist. In general, the colored strains were distinctly less resistant than the albino strains.
MICROBIC VIRULENCE AND HOST SUSCEPTIBILITY IN PARATYPHOID-ENTERITIDIS INFECTION OF WHITE MICE
Authors: Pritchett Ida W.
Published: June 2004

Four unrelated strains of mice were tested over a period of 1 year for their seasonal variation in susceptibility to per os feeding with a culture of Bacillus pestis caviæ of known virulence. Certain consistent fluctuations, determined to be in general agreement with those already recorded in a previous paper, were found and described.
THE RELATION OF THE THYROID GLAND TO THE SURFACE TENSION OF THE BLOOD PLASMA
Authors: Wilhelmj C. M. , Fleisher Moyer S.
Published: June 2004

1. Following thyroidectomy in guinea pigs, there is a gradual elevation of the surface tension of the blood plasma which reaches its height in from 19 to 22 days after operation. This elevation is probably permanent, since we have found it to persist for as long as 120 days.

2. In our experiments, we found a few thyroidectomized animals in which the surface tension of the plasma was still within normal limits 24 and 120 days after operation. We suggest that these exceptions are due to three possible factors: (1) incomplete thyroidectomy; (2) presence of accessory thyroid tissue; (3) compensatory activity on the part of other organs.

3. The surface tension of the plasma from operated animals is higher than that from controls in both the initial and 20 minute determinations, but the difference is greater at the 20 minute period.

4. The time-drop (difference between the initial and 20 minute determinations) is somewhat greater in the plasma from normal than in that from operated animals.

5. It is suggested that these changes are due to a decrease in the amount of certain normally occurring surface-active substances, the production of which is directly or indirectly dependent upon the thyroid gland.
THE RELATION OF THE THYROID GLAND TO THE SURFACE TENSION OF THE BLOOD PLASMA
Authors: Wilhelmj C. M. , Fleisher Moyer S.
Published: June 2004

1. Determinations of the surface tension of blood plasma from guinea pigs, before and after feeding thyroxin, showed in most cases a definite decrease. Out of twenty-seven experimental animals, twenty showed a depression in the surface tension which ranged from 1.9 to 13.9 dynes, with an average of 5 dynes. Six animals showed variations hardly exceeding the limits of experimental error, while one showed an elevation of 1.1 dynes.

2. Six normal control animals, bled on the same days and kept under identical conditions, showed differences in the two determinations which ranged from a decrease of 0.5 to an increase of 0.6 of a dyne. One other control showed a drop of 1 dyne.

3. Two animals which had been fed large quantities of thyroid extract over a period of 10 days, gave values considerably below normal. One of these animals survived, and after 11 days during which no thyroid extract was given, the surface tension was found again to be within normal limits.

4. The hypothesis is advanced that these changes are due to an increase in the amount of certain normally occurring surface-active constituents, which are produced as a result of increased cellular metabolism.
THE ORIGIN OF THE LEPRA CELL
Authors: Oliver Jean
Published: June 2004

1. By means of the method of vital staining it is found that the lepra cell in rat leprosy is derived from the histiocyte.

2. From the similarity in morphology and function of the lepra cells in this condition and those of human leprosy, it seems likely that derivation of the cells in the two conditions is similar.
NUCLEAR INCLUSIONS IN THE TESTICLES OF MONKEYS INJECTED WITH THE TISSUE OF HUMAN VARICELLA LESIONS
Authors: Rivers Thomas M.
Published: June 2004

Eosin-staining nuclear inclusions resembling those deemed characteristic of a certain well known group of filterable viruses, amongst which is varicella, were found in vervets' testicles inoculated with emulsified tissue of human varicella lesions.
EFFECT OF THYROIDECTOMY AND OF THYMECTOMY IN EXPERIMENTAL SYPHILIS OF THE RABBIT
Authors: Pearce Louise , Van Allen Chester M.
Published: June 2004

Experiments are described in which the thyroid or thymus gland of rabbits was removed prior to inoculation of the animals with Tr. pallidum. The effect of these procedures is described from the standpoint of the manifestations of the disease. After complete thyroidectomy, the disease was considerably more severe than in the controls and very markedly so in certain instances. Partial tyroidectomy, on the other hand, resulted in a milder disease than that of the controls. The effect of complete thymectomy was less pronounced than that of either complete or partial thyroidectomy, but, in general, the syphilis resembled that in partially thyroidectomized animals.

These effects are discussed in relation to the host's reaction and resistance to experimental syphilis and the conclusion was reached that the integrity and balance of the glands of internal secretion play an important rôle in the mechanism of defense against this infection.
VARIATIONS IN CO2 REQUIREMENTS AMONG BOVINE STRAINS OF BACILLUS ABORTUS
Authors: Smith Theobald
Published: June 2004

Strains of Bacillus abortus freshly isolated vary in their CO2 requirements. The origin and sources of the strains growing with less dependence on CO2 (or sealing) may be in vaccinal strains or possibly in continued existence in the udder. The importance of these possibilities makes it desirable that all strains isolated should be subjected to some such test as is outlined in these pages.
FURTHER DATA ON THE EFFECT OF VACCINATION AGAINST BOVINE INFECTIOUS ABORTION
Authors: Smith Theobald , Little Ralph B.
Published: June 2004

The partial protection afforded by four injections of a heated culture of Bacillus abortus of normal virulence during the first pregnancy is in part lost in the second. The superiority of a single injection of a living culture of relatively low virulence is evident in both pregnancies. In the experiment described, the protection was complete.
COMPENSATORY HYPERTROPHY OF THE ADRENAL CORTEX
Authors: MacKay Eaton M. , MacKay Lois Lockard
Published: June 2004

1. Removal of one adrenal in the albino rat is followed by hypertrophy of the remaining gland. In the case of female rats 90 days of age this compensatory hypertrophy amounted to 61 per cent.

2. The increase in size of the whole gland is due entirely to hypertrophy of the cortex. This increase in cortical tissue amounted to approximately 91 per cent and was due in large part if not entirely to an increase in the size of the cells.

3. No increase in the size of the medulla or its cells was found.