bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasonographic diagnosis in abdominal tuberculosis
Authors: Sheikh M , Moosa I , Hussein FMY , Qurttom MAF , Behbehani AI
Published: July 2002

Sonographic findings were retrospectively analysed in 39 patients with proven abdominal tuberculosis (TB). The patients were treated over 15 years at a major teaching hospital, Mubarak Al‐Kabber Hospital, in Kuwait. The findings included clear or complex ascites with fine strands, loculations and debris. The other findings were lymphadenopathy, bowel wall thickening, omental mass, focal lesions in the liver and spleen and psoas abscess. The sonographic findings in abdominal TB are not specific but may give valuable information to prevent unnecessary laparotomy.
Squamous cell carcinoma of the lip. Patterns of relapse and outcome: Reporting the Westmead Hospital experience, 1980–1997
Authors: Veness Michael J , Ong Colin , Cakir Burcu , Morgan Gary
Published: July 2002

Australia has one of the highest rates of squamous cell carcinoma of the lip in the world. Despite a high cure rate, many studies report relapse rates of between 5% and 20% with an associated mortality of 5–10%. The aim of this study was to review the patterns of relapse and outcome for patients treated at Westmead Hospital, Sydney. Ninety‐three eligible patients were identified in a retrospective review of all lip cancer patients referred to Westmead Hospital between 1980 and 1997. Relevant data were extracted from the treatment files and included contact with referring doctors and utilizing the Cancer Council Registry. Equal numbers of patients were treated with radiotherapy alone or surgery (± adjuvant radiotherapy). The majority of patients were male (78.5%) with T1N0 cancers (64.5%) of the lower lip. A minority (5.4%) had nodal disease at diagnosis. Following treatment, 31 (33.3%) patients relapsed, 11 at the primary site, 18 at the regional nodes and two at both sites simultaneously. Patients treated with a combined approach (RTx/Sx) experienced a better outcome. Overall cancer‐specific survival at 5 years was 85%. These findings highlight a disturbing relapse rate and mortality for a subgroup of patients diagnosed with a more aggressive form of lip cancer. Treatment and follow up of these patients should accordingly be more aggressive.
NK cells and apoptosis
Authors: Warren Hilary S , Smyth Mark J
Published: July 2002

Natural killer (NK) cells are a cell of the innate immune system that play an important role in the early response to viral infections and tumours. Natural killer cells are cytolytic, and secrete cytokines that influence the developing antigen‐specific immune response. In the present article the NK cell surface molecules regulating effector function, the NK cell effector mechanisms involved in apoptosis, and the role of NK cell effector mechanisms in immune responses are reviewed.
Tropical mangrove ecology: Physical and biotic factors influencing ecosystem structure and function
Authors: Lee S. Y.
Published: July 2002

Our understanding of the ecology of tropical mangals has strong practical implications for the management and conservation of these threatened ecosystems. Earlier models of tropical mangals proposed overwhelming influences by physical forces and processes such as the tidal regime or geomorphology on ecosystem structure and function. Recent findings from especially the Indo‐Pacific mangals suggest also considerable influence from biotic agents and processes such as sesarmine crab feeding and bioturbation activities in shaping the ecology of tropical mangals. I argue that more research attention should be paid to the study of the interplay between physical and biotic influences in the ecology of tropical mangals. Examples in litter dynamics and community determination are given to illustrate how biotic influences may respond to changes in the physical setting of mangals. This necessitates an approach integrating the two sources of influences. Despite decades of increased research effort, answers to many fundamental questions concerning practical management issues of tropical mangals are still largely unavailable. The often‐acclaimed functions and values of tropical mangals also have to be critically assessed in the light of existing and future data. It is proposed that research effort should also be targeted towards the assessment and mitigation of the predicted impacts of urgent problems faced by tropical mangals (e.g. conversion to aquaculture ponds, pollution) in order to secure their long‐term conservation and wise management.
Expression of periglandular tenascin‐C and basement membrane laminin in normal prostate, benign prostatic hyperplasia and prostate carcinoma
Authors: Xue  , LI  , Latijnhouwers  , Smedts  , Umbas  , Aalders  , Debruyne  , De La Rosette  , Schalken
Published: July 2002

Objective

 To evaluate the structural relationship of the distribution between tenascin (tenascin‐C, an extracellular matrix glycoprotein involved in stromal–epithelial interactions in both normal and pathological conditions) and laminin, an important component of the basement membrane, in normal and neoplastic human prostate, and to establish whether changes in the basement membrane are accompanied by changes in tenascin staining.

Materials and methods

 Seventy‐five snap‐frozen prostate samples representing normal glands, nodular benign prostatic hyperplasia and prostate carcinoma were stained for tenascin. From these, 15 samples were selected for dual‐immunofluorescence staining and a confocal laser scan microscope was used to simultaneously visualize tenascin and laminin immunoreactivity.

Results

 Tenascin was expressed in the extracellular matrix, mainly at the periphery of the glands, in tumour foci and blood vessels. In cases with intact basement membranes, e.g. normal glands and hyperplastic lesions, tenascin expression was weak. Low‐ and moderate‐grade tumours were characterized by strong tenascin expression, while laminin expression was weak and/or showed discontinuities, indicating disturbances in basement membrane composition. High‐grade tumours had sparse tenascin staining and a marked loss of laminin immunoreactivity.

Conclusion

 These results indicate that periglandular tenascin expression correlates with the integrity of the basement membrane in the human prostate. By influencing stromal–epithelial interactions, tenascin may play a role in maintaining tissue homeostasis in the prostate.
Antiretroviral treatment of central nervous system HIV‐1 infection: a review
Authors: Gisslén M , Hagberg L
Published: July 2002

HIV‐1 infects the central nervous system (CNS) and it has been feared that the CNS may be a sanctuary site where HIV‐1 could hide and continue to replicate despite otherwise effective antiretroviral treatment. Neurological HIV‐1 related symptoms, cerebrospinal fluid (CSF) viral load, intrathecal immunoactivation and CSF drug concentration measurements are considered in this review of antiretroviral treatment effects on CNS HIV‐1 infection. We conclude that antiretroviral combination treatment regimens improve neurocognitive symptoms in HIV‐1 infection and substantially lower CSF viral load. The threat of an increasing number of patients with neurological symptoms and continued HIV‐1 replication in the brain despite otherwise effective antiretroviral therapy has not yet proved to be a problem. It is, however, important to keep this potential risk in mind, and more longitudinal prospective studies addressing the issue of antiretroviral treatment effects on CNS HIV‐1 infection are needed.
Active emmetropization — evidence for its existence and ramifications for clinical practice
Authors: Wildsoet C. F.
Published: July 2002

There is increasing evidence from animal studies in support of the concept of an active emmetropization mechanism which has potentially important clinical ramifications for the management of refractive errors.

Recent research into retractive development and emmetropization is reviewed, with emphasis given to work involving the chick, tree shrew and monkey, which represent the three most widely used animal models in this field. The findings of this research are reviewed in a clinical context.

Compensatory eye growth responses to focusing errors imposed by lenses represent the most compelling evidence for active emmetropization. These observations are complemented by other evidence showing recovery from induced refractive errors such as form‐deprivation myopia. Of the animals listed above, chicks show the most impressive emmetropization, being able to compensate fully (using choroidal and scleral mechanisms) to lens powers ranging from +15 D to ‐10 D. The range of lens powers eliciting appropriate compensatory responses is narrower in the tree shrew and monkey, and the response patterns generally are also more complex to interpret. These data relate to young animals and together indicate refractive plasticity during development. Extrapolation of these findings to humans predicts that natural emmetropization will be inhibited in neonates by early intervention with prescription lenses, and that refractive correction of myopia will lead to accelerated progression.

This convincing evidence for active emmetropization warrants due consideration in developing clinical management strategies for refractive errors.
Wood Thrush Populations Are Not All Sinks in the Agricultural Midwestern United States
Authors: Fauth Peter T.
Published: July 2002

Abstract: Conservation strategies for forest‐breeding, Neotropical migratory birds focus on the identification and preservation of source habitats. In sources, populations maintain relatively high levels of reproductive success, whereas in sinks, reproductive success is consistently below net replacement rate. In agricultural regions of the midwestern United States, forest patches of various sizes appear to act as sinks for Neotropical migrants. In 1994–1996 I monitored Wood Thrush (  Hylocichla mustelina) nests in four forest patches in an agricultural landscape in northern Indiana. Given the prevailing estimates of adult and juvenile survival, I report productivity data that show substantial annual variation and that are sufficient to suggest the maintenance of temporal sources. Indeed, some Wood Thrush populations may act as source habitats in regions with relatively high levels of Brown‐headed Cowbird (  Molothrys ater) parasitism and nest predation because pairs produce multiple clutches and have the ability to fledge cowbirds and their own young from parasitized nests. My results and those from other studies of Wood Thrushes in landscapes with fragmented forests illustrate the variable ways in which source‐sink dynamics are affected by habitat fragmentation. In some agricultural regions, populations in small forest patches may act as sources for Wood Thrushes and may be a legitimate focus of conservation efforts aimed at some migratory songbirds.
Genetic Diversity and the Reintroduction of Meadow Species
Authors: Smulders M. J. M. , van der Schoot J. , Geerts R. H. E. M. , Antonisse‐de Jong A. G. , Korevaar H. , van der Werf A. , Vosman B.
Published: July 2002

Abstract: Restoration of formerly nutrient‐poor and species‐rich grasslands generally leads to an increase in species diversity. However, species without a persistent seed bank and with poor dispersal ability often do not re‐establish spontaneously. Here, reintroduction is an option. If existing populations are comparable in their genetic composition, any population will do. This is not the case if populations have local adaptations. Unfortunately, whether populations are adapted locally is not easily determined, in contrast to assessing differentiation using neutral genetic markers. We used AFLP to study genetic diversity of Cirsium dissectum and Succisa pratensis within and among several Junco‐Molinion plant communities in the Netherlands (up to 200 km apart) that were potential source populations, and followed the reintroduction using seeds from these populations. Also, vegetative growth phase characteristics of three populations of C. dissectum were analyzed under controlled conditions. Most of the genetic variation in these cross‐fertilizing species was found within populations. Small but significant genetic differences in band frequencies were found among populations (Fst 0.100 ‐ 0.135). The first generation of reintroduced plants contained less polymorphic bands than the source populations. The genetic differences caused by reintroduction using a limited number of seeds (founder effects) were significant in all except one case (Fst 0.012 ‐ 0.101 between source and corresponding reintroduced population), but the magnitude was smaller than the source population differentiation. In assignment tests, reintroduced populations resembled their source population more than any other population, but all populations contained sizeable proportions of plants that were assigned to most similar plants from other populations, indicating that the populations are only marginally distinct. Calculations show that reintroduction from more than one source population introduces significantly more polymorphic bands into the new population, capitalizing on the existence of band frequency differences among populations.
Cooperative growth phenomena in silicon/germanium low-temperature epitaxy
Authors: Meyerson Bernard S. , Uram Kevin J. , LeGoues Francoise K.
Published: July 2002

A series of Si:Ge alloys and structures has been prepared by ultrahigh-vacuum chemical vapor deposition. Alloys of composition 0≤Ge/Si≤0.20 are readily deposited at T=550 °C. Commensurate, defect-free strained layers are deposited up to a critical thickness, whereupon the accumulated stress in the films is accommodated by the formation of dislocation networks in the substrate wafers. A cooperative growth phenomenon is observed where the addition of 10% germane to the gaseous deposition source accelerates silane’s heterogeneous reaction rate by a factor of 25. A model is proposed where Ge acts as a desorption center for mobile hydrogen adatoms on the Si[100] surface, accelerating heterogeneous silane pyrolysis by the enhanced availability of chemisorption sites.
Potential use of the ruby R2 line shift for static high-pressure calibration
Authors: Gupta Y. M. , Shen X. A.
Published: July 2002

Results of shock-wave experiments to examine ruby R-line shifts for uniaxial strain compression along the crystal a axis are summarized and compared with previous c-axis results [P. D. Horn and Y. M. Gupta, Phys. Rev. 39, 973 (1989)]. The present results show that R1-line shift with compression depends on both nonhydrostatic stresses and crystal orientation. Hence, pressure determination using R1-line shifts in a nonhydrostatic environment can lead to errors. In contrast, the R2-line shift depends only on density compression and is independent of nonhydrostatic stresses and crystal orientation. These findings suggest the use of R2-line shifts for pressure calibration under nonhydrostatic loading conditions.
GaAs tetrahedral quantum dot structures fabricated using selective area metalorganic chemical vapor deposition
Authors: Fukui T. , Ando S. , Tokura Y. , Toriyama T.
Published: July 2002

New GaAs quantum dot structures, called tetrahedral quantum dots (TQDs), are proposed to make a zero-dimensional electron-hole system. The TQDs are surrounded by crystallographic facets fabricated using selective area metalorganic chemical vapor deposition (MOCVD) on (111)B GaAs substrates. The calculated energy sublevel structures of zero-dimensional electrons in a GaAs TQD show large quantum size effects, because electrons are confined three dimensionally. GaAs and AlGaAs tetrahedral facet structures on (111)B GaAs substrates partially etched into a triangular shape were grown using MOCVD. Tetrahedral growth with {110} facets occurs in the triangular areas. The cathodoluminescence intensity map for GaAs tetrahedrons buried in AlGaAs shows the tetrahedral dot array.
Heteroepitaxy of carbon on copper by high-temperature ion implantation
Authors: Lee S.-Tong , Chen Samuel , Braunstein G. , Feng X. , Bello I. , Lau W. M.
Published: July 2002

The recently reported carbon-ion-implantation-outdiffusion method [J. F. Prins and H. L. Gaigher, Mater. Res. Soc. Sym. Proc. (to be published, 1991)] of growing epitaxial diamond layers on copper was carefully examined. X-ray diffraction, Raman scattering, and transmission electron diffraction characterization of films prepared by implanting 200 keV carbon ions into (100), (110), (111), and (210) copper, held at temperatures of 850–1000 °C, showed that the films were invariably highly oriented crystalline graphite. No evidence has been found to support the claim that diamond was formed by this implantation-outdiffusion method.
Record high recombination lifetime in oxidized magnetic Czochralski silicon
Authors: Pang S. K. , Rohatgi A.
Published: July 2002

This letter demonstrates that recombination lifetimes in excess of 5 ms can be achieved in the oxidized magnetic Czochralski (MCZ) silicon by a combination of high-purity crystal growth, proper cleaning and oxidation conditions. Lifetime studies were conducted at room temperature on as-grown as well as oxidized 2000 Ω cm low oxygen (∼5 ppm) MCZ silicon by an injection sensitive, contactless photoconductive decay technique with controlled injected carrier densities up to 1017 cm−3. Record Shockley–Read–Hall lifetimes of 8.5 and 6.6 ms were achieved in the as-grown and oxidized MCZ wafers, respectively. However, oxidized Czochralski (CZ) silicon with 14.2 ppm oxygen gave lifetime of only 200 μs due to much higher concentrations of as-grown and process-induced defects. Lifetime versus injection level analysis gave ambipolar Auger recombination C coefficient of 1.1×10−30 (±9%) cm6 s−1 before and after the oxidation in both MCZ and CZ silicon. Unlike the C coefficient, the B coefficient (radiative band-to-band + trap-assisted Auger) in low-oxygen MCZ silicon was found to be four times smaller than the value in high oxygen CZ silicon.
Improvement of viewing angle characteristics in a twisted-nematic liquid-crystal display by using a cholesteric liquid-crystal compensation layer
Authors: Hatoh Hitoshi , Ishikawa Masahito , Hirata Junko , Hisatake Yuzo , Yamamoto Tomiaki
Published: July 2002

Viewing angle characteristics of a twisted nematic (TN) liquid-crystal display (LCD) have been improved by inserting a planar aligned cholesteric liquid crystal compensating layer between the TN cell and a polarizer. Dependencies of the electro-optical characteristics of the novel LCD on the retardation, ratio of thickness to the pitch (dc/p) and twist-sense in the cholesteric layer are discussed. A thin-film transistor addressed LCD with a wide viewing angle has been developed based on this novel cell construction and its display performance is reported.
Role of Coulomb repulsion in 4f orbitals in electrical excitation of rare-earth impurities in semiconductors
Authors: Tiedje T. , Colbow K. M. , Gao Y. , Dahn J. R. , Reimers J. N. , Houghton D. C.
Published: July 2002

The role of the on-site Coulomb repulsion energy in the electrical excitation of rare-earth ions by minority carrier injection in semiconductors is examined. Resonant photoemission measurements of the interfacial electronic energy level alignment in NdF3/silicon heterojunctions show that the large Coulomb repulsion energy of the atomiclike 4f orbitals prevents the direct excitation of the 4f levels by either electron or hole capture.
Low energy ion bombardment induced roughening and smoothing of SiO2 surfaces
Authors: Chason E. , Mayer T. M.
Published: July 2002

Surface roughening and smoothing of SiO2 by low energy ion bombardment were investigated using in situ energy dispersive x-ray reflectivity. Bombardment of nominally smooth surfaces (initial roughness approx. 0.4 nm) by 1 keV Xe increases the surface roughness linearly with fluence. Bombardment of initially rough surfaces (roughness approx. 1 nm) by 0.2–1 keV H results in an exponential decrease in roughness with fluence at a rate that increases with energy. The smoothing rate has a different energy dependence than the etching rate, ruling out a simple relation between material removal and surface morphology. A H ion induced relaxation mechanism is suggested for the smoothing behavior.
10 nm electron beam lithography and sub-50 nm overlay using a modified scanning electron microscope
Authors: Fischer P. B. , Chou S. Y.
Published: July 2002

Gratings of 10 nm wide metal lines 30 nm apart, and quantum transistor gates with 10 nm wide gaps over 300 nm long between two metal rectangles have been repeatedly achieved on thick GaAs substrates using a modified scanning electron microscope operated at 35 keV and liftoff of Ni/Au. Furthermore, multilevel electron beam lithography with a standard deviation (3σ) of an overlay accuracy (30 deviation) of 50 nm has been achieved using the same modified scanning electron microscope.
Synthesis of luminescent silicon clusters by spark ablation
Authors: Saunders Winston A. , Sercel Peter C. , Lee R. B. , Atwater Harry A. , Vahala Kerry J. , Flagan Richard C. , Escorcia-Aparcio Ernesto J.
Published: July 2002

The synthesis of luminescent nanometer-scale Si clusters by spark ablation from a crystalline Si substrate is described. The cluster source, described in the text, generates clusters in a flowing Ar stream at atmospheric pressure. Electron microscopy reveals that the clusters have diameters in the 2–4 nm size range. The luminescence spectra of the clusters, similar to that of porous Si, are presented.
Photopumped room-temperature edge- and vertical-cavity operation of AlGaAs-GaAs-InGaAs quantum-well heterostructure lasers utilizing native oxide mirrors
Authors: Ries M. J. , Richard T. A. , Maranowski S. A. , Holonyak N. , Chen E. I.
Published: July 2002

Data are presented on the 300-K continuous and pulsed photopumped laser operation of AlyGa1−yAs-GaAs-InxGa1−xAs quantum-well heterostructure (QWH) crystals that utilize large-index-step high-contrast distributed Bragg reflector mirrors. The mirrors are formed by selective lateral oxidation (H2O+N2, 425 °C) of three lower and three upper AlAs layers in the structure, resulting in enhanced cavity Q in the vertical direction. The laterally oxidized mirrors, a small lower and an upper ‘‘stack’’ that sandwich a lateral waveguide and double QW active region, are of sufficient quality to permit vertical-cavity laser operation of the QWH crystals.
Fast thermoelectric response of normal state YBa2Cu3O7−δ films
Authors: Zeuner S. , Prettl W. , Lengfellner H.
Published: July 2002

Normal state YBa2Cu3O7−δ films, epitaxially grown ‘‘off-c axis’’ with tilt angles up to 20° are shown to be fast thermoelectric detectors for radiation from UV to far infrared wavelengths. Upon radiation heating of the tilted films a thermoelectric voltage arises due to the anisotropy of the thermopower in YBa2Cu3O7−δ. The response time is limited by the decaying temperature gradient and thus by heat diffusion. For thin films we have measured a response time from ≲1 ns in the UV to ∼5 ns in the far infrared. Because of the wavelength dependent reflectivity, the responsivity of the films varies between 0.5 V/MW and 20 V/MW. Thus, thin tilted YBa2Cu3O7−δ films can be used as fast room temperature detectors over a wide spectral range.
Direct bonding of LiNbO3 single crystals for optical waveguides
Authors: Tomita Yoshihiro , Sugimoto Masato , Eda Kazuo
Published: July 2002

A new fabrication method of optical waveguides using direct bonding of lithium niobate single crystals without using any bonding agents has been developed. The bonded interface was found very uniform and the bonding was performed in an atomic scale in spite of a relatively low heat-treatment temperature of 400 °C. It was confirmed to be possible to fabricate optical waveguides using the direct bonding. This method is very attractive to obtain high-performance optical guided-wave devices because of its versatility.
Multichordal charge-exchange recombination spectroscopy on the DIII-D tokamak
Authors: Seraydarian Raymond P. , Burrell Keith H.
Published: July 2002

Ion temperature and rotation speed profiles will be measured spectroscopically on DIII-D using charge-exchange-induced excitation of spectral lines. Compared to the spectroscopic system used on Doublet III, the DIII-D system will have improved spatial and temporal resolution, reduced instrumental contribution to line broadening, and the capability to measure both toroidal and poloidal rotation.
Multimode ionization cell for gas chromatographic detection
Authors: Wise M. B. , Buchanan M. V. , Parks S. K. , Haas J. W.
Published: July 2002

A user-selectable, multimode, beta-ionization cell has been developed for gas chromatographic (GC) detection. The system consists of a modified dc current (nonpulsed) electron capture cell enclosed in a stainless-steel vacuum chamber. A gas mixing manifold connected to the input of the detector enables various reagent gases to be mixed with the GC effluent prior to entering the detector cell. Simply by varying the pressure of the reagent gas inside the detector from atmospheric to as low as 50 mTorr, one of four different modes of operation can be achieved. These include (1) conventional electron capture detection (atmospheric pressure), (2) cross-section ionization electron emission (<1 Torr), (3) low-pressure argon ionization electron emission (1–10 Torr), and (4) mixed electron capture/electron emission (100–300 Torr). One advantage of this detector is the ability to switch between selective detection (electron capture) and universal detection (argon ionization) by only changing the operating pressure in the cell. Another important feature is that the degree of selectivity is continuously tunable in the mixed electron capture/electron emission mode of operation. This is due to a dramatic pressure dependent competition between argon ionization electron emission and capture of near-thermal electrons by compounds passing through the detector. This selectivity appears to be strongly related to the electron affinity of compounds, with those exhibiting the highest electron affinities capable of capturing electrons at the lowest pressures. This enables classes of compounds, such as polychlorinated biphenyls (PCBs), to be detected in the presence of hydrocarbons. Additionally, compounds such as isomeric polycyclic aromatic hydrocarbons (PAH) can be readily distinguished using this detector.
Temperature distribution in a cylindrical furnace for high-pressure use
Authors: Kawashima Y. , Yagi T.
Published: July 2002

Temperature distribution in a cylindrical furnace used in a high-pressure apparatus has been calculated by the difference method. The calculated values are in good agreement with the experimental observations obtained by an x-ray diffraction method. A steep temperature gradient exists in a simple cylindrical furnace. In order to obtain a homogeneous temperature distribution, a furnace composed of a graphite tube and two graphite disks has been designed. It has been demonstrated that a homogeneous temperature distribution can be obtained by selecting proper resistivities for the tube and the disks. The design requires a large power input, which could result in a shorter lifetime of the anvils.
Measurement of Seebeck coefficient using a large thermal gradient
Authors: Wood C. , Chmielewski A. , Zoltan D.
Published: July 2002

The integral method of measuring the Seebeck voltage V(T), in which one end of the sample is held at a fixed temperature TC, and the other end is varied through the temperature T range of interest, has been adapted to short rod-shaped samples. The Seebeck coefficient S is obtained from the slope of the V(T) vs T curve, i.e., S=dV(T)/dT. The apparatus has been completely automated such that the specimen is automatically cycled through a preselected temperature range, up to a maximum temperature of 1000 °C, and the V(T), T, and TC values are acquired, stored, and analyzed by means of a microcomputer. Simplicity of sample handling and minimal operator involvement make this method well suited to the survey of large numbers of samples.
Compact wide-aperture hyperbolic analyzers
Authors: Curtis C. C. , Hsieh K. C.
Published: July 2002

Compact electrostatic analyzers that employ a new geometry are described. They accept collimated beams of ions through relatively wide (non-slit-like) inlet apertures and focus them at various locations, depending on the ion energy per charge, along rectangular position-sensing detectors. Each analyzer has a dynamic range of 10 or more for a fixed deflection voltage. The focal line width at a given energy is a small fraction of the inlet aperture width, and the focal lines are approximately coplanar.
Magnetic circulating pumps for use over wide ranges of temperature and pressure
Authors: Rogers W. J. , Fontalba F. , Capps E. F. , Holste J. C. , Marsh K. N. , Hall K. R.
Published: July 2002

This note presents designs for two inexpensive, magnetic circulating pumps. The first pump is designed for corrosive fluids over wide ranges of temperature, to 700 K, and pressure, to 200 MPa, and for flow rates to 6 cm3/s. The second pump is designed primarily for gases at temperatures to 500 K, pressures from 6 kPa to 20 MPa, and flow rates to 60 cm3/s. Each pump consists of a simple cylinder and piston with a central flow channel and gate operated by sample inertia.
Statistics of ion-induced electron emission from a clean metal surface
Authors: Lakits G. , Aumayr F. , Winter H.
Published: July 2002

With a novel combination of experimental approaches, ion-induced electron emission from clean polycrystalline gold bombarded with (1–5 keV/amu) H+, H+2, and H+3 has been studied by measuring total electron yields, ejected-electron energy distributions, and, in particular, electron emission statistics (ES). Evaluation of ES included corrections for backscattering of electrons from the surface of the applied solid-state electron detector. By comparing ES for atomic and molecular ions of equal impact velocities, a negative molecular effect could be clearly demonstrated. This effect was further investigated by comparing measured ES for molecular ion impact with ES synthesized from measured ES for H+ and H+2 ion impact, respectively. The quality of approximating measured ES by Poisson and Polya statistical distributions was investigated in detail and found to be generally unsatisfactory.
X-ray microtomography with monochromatic synchrotron radiation (invited)
Authors: D’Amico K. L. , Deckman H. W. , Dunsmuir J. H. , Flannery B. P. , Roberge W. G.
Published: July 2002

We review results obtained with the Exxon Microtomography apparatus. The technique is based on tomographic methods widely used in medicine and nondestructive evaluation. When used with a tunable x-ray source, it is a powerful diagnostic and research tool for a wide variety of materials problems. It is capable of producing maps of the interior structure and chemical composition of samples approximately 0.5–1.0 mm in size, with spatial resolution in the map of the density variations approaching 10.0 μm.
The KSU cryogenic electron-beam ion source
Authors: Stockli Martin P. , Cocke C. L. , Richard P.
Published: July 2002

We built a cryogenic electron-beam ion source which is now in operation. We report some experiences and results of the start-up phase, which was aimed at producing beams of highly charged argon. In March 1989 the first ions were extracted and identified as argon 17+ using Donets’ x-ray technique. In April we started performing diagnostics with a 90° double-focusing analyzing magnet to study the charge-state distributions. In June we extracted beams with fully stripped argon 18+ as the most abundant argon charge state.
Compact ECR ion sources with permanent magnets in a cusp geometry and in a magnetic mirror structure
Authors: Delaunay M.
Published: July 2002

Two compact Electron Cyclotron Resonance (ECR) ion sources exclusively built with permanent magnets in a cusp geometry and in a magnetic mirror structure are compared. The microwave discharge power is 60–120 W at a frequency of 2.45 GHz. The cusp structure enables to produce an argon-ion current of 1.5 mA at an extraction voltage of 2 kV with an aperture of 4 mm diameter at a gas pressure of 10−3 mbar. The ion source built with a magnetic mirror operates at lower pressure (10−4 mbar) with an ion current density of 5 mA/cm2 (the total current is 0.6 mA). Spectroscopic measurements of photons emitted by an oxygen plasma enable us to detect multicharged ions such as O4+ and O5+ ions. With these two magnetic structures, sharp variations of current density with gas flow rates are observed and the different ranges of operating pressure are presented.
Processing and hardness of electrodeposited Ni/Al2O3 nanocomposites
Authors: Oberle R. R. , Scanlon M. R. , Cammarata R. C. , Searson P. C.
Published: July 2002

Nanocomposite Ni/Al2O3 films have been produced by electrochemical deposition where 50 and 300 nm Al2O3 particles are dispersed in a nickel matrix. These films exhibit considerable enhancements in their hardness in comparison to pure nickel. The strengthening mechanism is explained in terms of an Orowan bowing hardening mechanism and, hence, related to the volume fraction of the reinforcing phase. These films may have application as strong coatings that retain many of the physical properties (e.g., optical, thermal, electrical) of the metal.
A new two-dimensional particle detector for a toroidal electrostatic analyzer
Authors: Tromp R. M. , Copel M. , Reuter M. C. , Horn von Hoegen M. , Speidell J. , Koudijs R.
Published: July 2002

We describe a new two-dimensional detector for the detection of ions scattered from a solid target, analyzed in energy and scattering angle by a toroidal electrostatic analyzer. The detector resolves the scattering angle with a resolution of 0.4° over a range of 25°, and the ion energy with a resolution of 120 eV over a range of 2000 eV, at 100 keV ion energy. The energy resolution of the spectrometer was improved with a factor 4 relative to its previous performance with a one-dimensional scattering angle detector, while−at the same time−the dose efficiency (count/μC) was improved by a factor 5–10.
Development of a film thickness probe using capacitance for asymmetrical two-phase flow with heat addition
Authors: Klausner J. F. , Zeng L. Z. , Bernhard D. M.
Published: July 2002

A film thickness probe based on capacitance measurements has been developed which is used to measure the liquid film thickness on both the upper and lower surface of a horizontal tube containing a two-phase mixture. Using appropriate nondimensionalization of the capacitance versus film thickness relationship, a new method has been developed in which the sensor may be used in temperature-dependent flow fields. The liquid film thickness probe was calibrated at room temperature and tested in a refrigerant R113 flow boiling facility over a 60 °C temperature span. Measurements made over a film thickness range of 25 mm using the capacitance probe are in close agreement with optical measurements made with a charge coupled device camera. In addition, spectral analysis of the probe signal allows for a trace of the low-frequency characteristics of the liquid film.
Extraction of infrared radiation from SPring-8
Authors: Hara M. , Be S. H. , Takeshita I. , Nanba T.
Published: July 2002

Extraction of infrared beams from SPring-8 storage ring is investigated. SPring-8 is a third generation insertion device oriented synchrotron radiation source in x-ray region. It is noticeable, however, that a highly powerful radiation source in infrared region can be obtained from the bending magnet because of the large bending radius of 40 m. In this wavelength region, SPring-8 storage ring has a very sharp natural collimation in the vertical direction and the source size is very small. Extraction of infrared radiation in wavelength of 2–25 μm was designed. Source is a bending magnet and a water-cooled copper mirror is incorporated into the crotch laid just downstream by the bending magnet. The design of crotch and the transport system is carried out.
Absolute calibration of a Mott polarimeter using surface Penning ionization
Authors: Oro D. M. , Lin Q. , Soletsky P. A. , Zhang X. , Dunning F. B. , Walters G. K.
Published: July 2002

A technique for absolute calibration of a Mott polarimeter is described that makes use of electrons of accurately known polarization obtained through surface Penning ionization. This approach provides higher count rates and lower uncertainties than obtained in earlier measurements based on gas-phase Penning ionization.
A low temperature, ultrahigh vacuum, microwave-frequency-compatible scanning tunneling microscope
Authors: Stranick S. J. , Kamna M. M. , Weiss P. S.
Published: July 2002

To expand the capabilities of the microwave frequency alternating current scanning tunneling microscope to include the ability to study isolated adsorbates and highly reactive surfaces, we have developed a low temperature, ultrahigh vacuum alternating current scanning tunneling microscope. In this alternating current scanning tunneling microscope, we employ the reliable beetle-style sample approach mechanism with a number of other components unique to a low temperature scanning tunneling microscope. These include the sample transfer, delivery, retrieval, storage, sputtering, and heating systems. This alternating current scanning tunneling microscope operates at 77 and 4 K.
Confocal theta microscope with three objective lenses
Authors: Lindek Steffen , Pick Rainer , Stelzer Ernst H. K.
Published: July 2002

A microscope using three water immersion objective lenses which realizes confocal, 4Pi-confocal and various confocal theta microscopies in fluorescence, transmission, scattered, and reflection mode is described. An argon-ion laser is the primary light source. A pulsed titanium-sapphire laser allows two-photon absorption fluorescence microscopy. The instrument has a predicted resolution of 100 nm along the illumination axis and a three-dimensional resolution of 5×106 nm3 for lenses each with a numerical aperture of 0.75. This is an improvement of an order of magnitude over a confocal fluorescence microscope using the same lens. Applications of the microscope range from observation of a sample at three different angles, to confocal theta fluorescence microscopy with multiphoton absorption. Since mounting and immersion media are identical, aberrations become negligible. The large working distance of 2 mm makes the instrument ideal for the observation of biological samples of up to 1.5 mm in diameter such as drosophila embryos.
Plasma potentials and performance of the advanced electron cyclotron resonance ion source
Authors: Xie Z. Q. , Lyneis C. M.
Published: July 2002

The mean plasma potential was measured on the LBL advanced electron cyclotron resonance (AECR) ion source for a variety of conditions. The mean potentials for plasmas of oxygen, argon, and argon mixed with oxygen in the AECR were determined. These plasma potentials are positive with respect to the plasma chamber wall and are on the order of tens of volts. Electrons injected into the plasma by an electron gun or from an aluminum oxide wall coating with a very high secondary electron emission reduce the plasma potential as does gas mixing. A lower plasma potential in the AECR source coincides with enhanced production of high charged state ions indicating longer ion confinement times. The effect of the extra electrons from external injection or wall coatings is to lower the average plasma potential and to increase the neτi of the ECR plasma. With sufficient extra electrons, the need for gas mixing can be eliminated or reduced to a lower level, so the source can operate at lower neutral pressures. A reduction of the neutral pressure decreases charge exchange between ions and neutrals and enhances the production of high charge state ions. An aluminum oxide coating results in the lowest plasma potential among the three methods discussed and the best source performance.
The Φ-factory DAΦNE as a source of infrared radiation: An estimate of source size and brilliance
Authors: Nucara A. , Calvani P. , Marcelli A. , Sánchez del Rio M.
Published: July 2002

The actual source area of a bending magnet emitting in the infrared range, has been calculated for the double annular Φ-factory for nice experiments (DAΦNE) under construction at Frascati. ‘‘Geometrical’’ broadening has been included. The actual brilliance ratio defined as the ratio between the brilliance of a synchrotron source and that of a blackbody, has been also evaluated for DAΦNE and compared with the Brookhaven NSLS source.
On the efficiency of the electron sheath heating in capacitively coupled radio frequency discharges in the weakly collisional regime
Authors: Buddemeier U. , Kortshagen U. , Pukropski I.
Published: July 2002

In low pressure, capacitively coupled rf discharges mode transitions in the shape of the electron energy distribution function on variation of the pressure have been observed previously, and have been interpreted as a transition from dominating stochastic to dominating Joule heating. In this letter we present a similar mode transition, which has been observed at constant discharge pressure on variation of the rf current density through the discharge. By comparison to a parametric kinetic model it is shown that a dependence of the sheath heating efficiency on the magnitude of the rf sheath potentials can be considered as a possible explanation of the mode transition.
A split beam method for measuring time-resolved circular dichroism
Authors: Wenzel Stephan , Buss Volker
Published: July 2002

An improvement to the Lewis–Kliger method for measuring transient circular dichroism on the nanosecond time scale is described. The method uses a single-probe beam that is split into two different beams of plane polarized light entering the sample and a retarder from opposite directions in different succession. Rochon polarizers are used as high-quality polarizing beam splitters to select the slow axis component of the emerging elliptical polarized light beams. The intensities of the light beams are determined by an imaging spectrograph coupled to an intensified charge coupled device detector. The split beam method reduces the need for very precise calibration of the central strain plate acting as a retarder and controlling the ellipticity of the probe light. The necessary calculations are simple and can be shown to be equivalent to the formulas derived by Lewis and Kliger. The static CD spectrum of vitamin B12 is presented and compared to a spectrum obtained with a commercial instrument and standard technique. The time resolution of the instrument is demonstrated by observation of photobleaching of carbon monoxy myoglobin from horse heart muscle.
Transmission electron microscopy investigation of the morphology of InP Stranski–Krastanow islands grown by metalorganic chemical vapor deposition
Authors: Georgsson K. , Carlsson N. , Samuelson L. , Seifert W. , Wallenberg L. R.
Published: July 2002

We have used transmission electron microscopy to determine the morphology of InP Stranski–Krastanow islands in GaInP, grown by metalorganic chemical vapor deposition at 580 °C. We investigated both capped and uncapped islands. It was found that the fully developed islands have the principal shape of truncated pyramids with a hexagonal base both before and after overgrowth. The planes defining the islands are of {001}, {110}, and {111} types. The base dimensions are 40–50 nm and 55–65 nm in the [1̄10] and [110] directions, respectively, and the height is 12–18 nm.
A photoelectron spectrometer for k-space mapping above the Fermi level
Authors: Greber T. , Raetzo O. , Kreutz T. J. , Schwaller P. , Deichmann W. , Wetli E. , Osterwalder J.
Published: July 2002

The setup of an electron spectrometer for angle-resolved photoemission is described. A sample goniometer offers the opportunity for angle scanned photoemission over 2π solid angle above the surface. A monochromatized high flux He discharge photon source is exploited to measure thermally populated electronic states above the Fermi level EF. At energies greater than EF+5kBT the signal from a constant density of states declines below the photoelectron background caused by photons with higher energies than He Iα (21.2 eV). For He IIα (40.8 eV) the residual photoelectron background is lower and photoemission up to 6kBT above EF can be performed. Data showing two cuts through the Fermi surface of silver are presented. Furthermore the dispersion of the Shockley surface state on Ag (111) above the Fermi energy is quantified.
A simple technique for investigating whispering gallery modes in optical fibers
Authors: Powell-Friend Y. , Phillips L. , George T. , Sharma A.
Published: July 2002

A simple technique for investigating whispering gallery modes in optical fibers is described. Unlike the conventional technique of winding a fiber around a mandrel, a bent fiber is produced simply by inserting it inside a commercial glass tube. The fiber naturally assumes a semicircular shape at the bend. It is shown that the loss spectrum due to whispering gallery modes is insensitive to small variations in the glass tube diameter. The glass tube with the bent fiber inside is used to fabricate a rugged interferometric temperature sensor which can be moved around even during measurements. Application of the technique for quality control is also demonstrated by measuring the variation of fiber buffer properties along the length of fiber.
A new instrument for collecting dynamic data of rotors
Authors: Jianfeng Li , Xiaochen Wang , Chuanmin Zhu , Zhiren Tian
Published: July 2002

A new and practical instrument to collect the dynamic data of rotors has been developed. The instrument is described and the signal transmitting properties have been tested. The test results show that the amplitude-frequency performance, the linear error, and the channel-isolation ability of this instrument satisfy the testing requirement. As an application example, this new instrument was used to test gear vibration on a gear testing table. The system has a very high anti-interference ability and excellent stability. The properties of this instrument are as follows: dynamic maximum frequency is 50 kHz, static sine distortion degree is less than 1%, dynamic channel isolation is −40 dB, dynamic linear error is less than 1%, both the static and dynamic gains are 50–200 times. The test results are consistent with the theoretical calculations. The system has been applied to collect dynamic data on rotors such as gears, axels, and engine propellers.
A simple single crystal sample temperature controller based on commercial components for ultrahigh vacuum surface science application
Authors: Dixon-Warren St. J. , Burson N. , Bondzie V. , Zhang L. , Yu Y. , Lucchesi L.
Published: July 2002

A simple temperature control system for ultrahigh vacuum (UHV) surface science applications has been developed. It is based on commercially available components and can be constructed with minimal electronics expertise. It controls the temperature of a single crystal sample in UHV over the range 80–1633 K using a type K thermocouple to monitor the temperature of the sample. The controller can be used to provide temperature ramps over the range 0–10 K/s.
A reactive laser ablation source for the production of thin films
Authors: Rexer Eric F. , Joshi Mukesh P. , DeLeon Robert L. , Prasad Paras N. , Garvey James F.
Published: July 2002

A discription of a thin film deposition source which is based upon the “Smalley metal cluster source” is presented. Our laser assisted molecular beam deposition source incorporates four major innovations: (1) placing the source so it sits external to the deposition chamber, (2) positioning the ablation target at an angle greater than 90° with respect to the laser entrance window, (3) placing the laser entrance window/lens further from the ablation target, and (4) the addition of a second optical window for laser alignment and in situ spectral analysis of the laser ablation plume. Novel molecules can be generated in this source through use of a reactive carrier gas. For example, employing a Ti target rod and O2 carrier gas; flat, uniform micron thick thin films of TiO2 can be easily generated.