bluuebunny/crossref_metadata_2025 huggingface dataset:
Intranasal Toxicity of BMS-181885, A Novel 5-HT1 Agonist
Authors: Schulze Gene E. , Proctor Jim E. , Dominick Mark A. , Weiss Amy E. , Flint Oliver P. , Srinivas Nuggehally R. , Durham Stephen K. , Schilling Beth E.
Published: July 2002

One-month intranasal toxicity studies were conducted with BMS-181885 at doses of 1.5, 9, or 15 mg/animal/day in rats and 4, 24, or 40 mg/animal/day in monkeys. A 1-month intermittent intranasal toxicity study was also conducted in monkeys at doses of 3, 6, and 12 mg/animal 3 days per week. BMS-181885 was generally well tolerated in rats but resulted in dose-dependent nasal mucosal injury, primarily characterized by subacute inflammation of the nasal mucosa, and degeneration, single-cell necrosis, and/or erosion of the olfactory epithelium and, to a lesser extent, the respiratory epithelium. In monkeys, daily BMS-181885 administration was well tolerated and produced similar dose-dependent nasal injury primarily characterized by subacute inflammation of the nasal mucosa with degeneration and erosion of the olfactory epithelium. In a separate experiment, intermittent administration also resulted in dose-dependent nasal injury. In cultured rat nasal mucosal cells, BMS-181885 was toxic to olfactory epithelial cells with a range of mean IC50s between 44 and 291 μM. In contrast, BMS-181885 had no effect on respiratory epithelial cells up to its maximum solubility. Cytochrome P450 inhibition had no effect on the toxicity of BMS-181885 in olfactory epithelial cells but produced dose-dependent toxicity in respiratory epithelial cells, which was not present previously. The in vitro data suggest that parent drug, rather than a toxic metabolite, caused the drug-associated nasal mucosal injury.
Characterization of a Dietary Ethanol Protocol for Cyp2e1 Induction in the CD-1 Mouse without Evident Hepatic Toxicity or Genotoxicity
Authors: Daiker Davis H. , Ward Jonathan B. , Schoenfeld Heidi A. , Witz Gisela , Moslen Mary Treinen
Published: July 2002

Although the CD-1 mouse strain has been used to investigate the toxicity of numerous substrates of Cyp2e1, limited information is available about responses of this strain to ethanol, a potent and clinically relevant inducer of this cytochrome P450 isozyme. Our goal was to characterize a dietary ethanol protocol for greater than threefold induction of hepatic Cyp2e1 in CD-1 mice without confounding alterations to other biotransformation enzymes or injury to known target tissues. Female CD-1 mice were fed the Lieber-DeCarli liquid diet containing 1.4 to 6.4% ethanol (v/v) for time periods of 1 to 12 weeks. A series of range-finding experiments indicated that the stock 6.4% ethanol diet caused rapid weight loss, whereas dietary ethanol concentrations less than or equal to 3.2% produced inadequate (i.e., less than threefold) induction of hepatic Cyp2e1. Suitable responses were observed in mice fed a 4.1% ethanol diet, namely, body weight gain equivalent to both pair-fed or rodent chow control groups plus consistent and stable induction of hepatic Cyp2e1 activities by greater than threefold without evidence of hepatic lipid peroxidation or histopathology. Evaluations of other representative biotransformation activities, including bone marrow quinone reductase and hepatic aldehyde dehydrogenase, showed no alterations with the 4.1% ethanol diet, except for a modest 20% decline in hepatic glutathione peroxidase. Unlike observations in other species, Cyp2e1 induction was not evident in bone marrow or spleen by Western blot. Mice given the 4.1% ethanol diet for 6 and/or 12 weeks showed no changes in cellularity of the spleen or bone marrow, frequency of hprt mutations in splenic lymphocytes, or percentage of DNA-protein crosslinks in bone marrow cells. These parameters were monitored because ethanol at high exposures is known to cause immunosuppression and mild genotoxicity. Female CD-1 mice fed a 4.1% ethanol liquid diet showed substantial (greater than threefold) induction of hepatic Cyp2e1 without confounding detrimental effects on the fiver, spleen, or bone marrow. Thus, this dietary ethanol protocol should be useful for future investigations of the role of Cyp2e1 induction on genotoxicity responses to Cyp2e1 substrates.
Determining the Potential of Aromatic Amines to Induce Cancer of the Urinary Bladder
Authors: Freudenthal Ralph I. , Stephens Ellen , Anderson Daniel P.
Published: July 2002

Aromatic amines have been associated with the induction of cancer of the urinary bladder. Commercial production started over 100 years ago in Europe, with the synthesis of a mauve pigment from aniline. The discovery of other pigments by combining aniline with various chemicals initiated the aniline dye industry. By the turn of the century, a correlation between working in the dyestuff industry and the development of bladder cancer was established. Initially thought to be the result of exposure to aniline, various investigators identified benzidine, beta-naphthylamine, and 4-aminobipheny 1 as the causative agents. Evaluations of various aromatic amines in rats, mice, guinea pigs, rabbits, dogs, and monkeys showed significant species differences, with the dog and monkey being the most sensitive species. Several laboratories related these species differences to differences in the respective routes by which the various species metabolized aromatic amines. Excellent correspondence was shown between metabolic activation of benzidine, 4-aminobiphenyl, and beta-naphthylamine in dogs and primates and the induction of bladder cancer. Rodents were shown to be unresponsive to human bladder carcinogens. The need to use data developed in the most sensitive species, the dog, is essential to accurately predict the carcinogenic potential of aromatic amines.
Sentence processing strategies in children with expressive and expressive‐receptive specific language impairments
Authors: Evans Julia L. , Whinney Brian Mac
Published: July 2002

The purpose of this study was to investigate the sentence comprehension strategies used by children with expressive and expressive‐receptive specific language impairments (SLI) within a language processing framework. Fourteen children with SLI (ages 6;10‐7;11) meeting strict selection criteria were compared to seven age‐matched and seven younger normal controls. Children were asked to determine the agent in sentences composed of two nouns and a verb (NVN, NNV, VNN) with animacy of the noun as a second factor. Results of group comparisons revealed that children with E‐SLI and ER‐SLI differed from each other in the comprehension strategies they employed as well as differing from both age‐matched and younger normal language control groups. Children with E‐SLI relied exclusively on a first noun as agent strategy across all conditions, whereas children with ER‐SLI used animacy cues when available. Additionally, maximum likelihood estimates were calculated to investigate individual patterns of performance under different cue conditions. Results revealed a significant correlation between severity of receptive language abilities and the type of strategy used, with better receptive language skills being highly correlated with children's use of word order cues.
Age-Related Atrophy of Motor Axons in Mice Deficient in the Mid-Sized Neurofilament Subunit
Authors: Elder Gregory A. , Friedrich Victor L. , Margita Alla , Lazzarini Robert A.
Published: July 2002

Neurofilaments are central determinants of the diameter of myelinated axons. It is less clear whether neurofilaments serve other functional roles such as maintaining the structural integrity of axons over time. Here we show that an age-dependent axonal atrophy develops in the lumbar ventral roots of mice with a null mutation in the mid-sized neurofilament subunit (NF-M) but not in animals with a null mutation in the heavy neurofilament subunit (NF-H). Mice with null mutations in both genes develop atrophy in ventral and dorsal roots as well as a hind limb paralysis with aging. The atrophic process is not accompanied by significant axonal loss or anterior horn cell pathology. In the NF-M–null mutant atrophic ventral root, axons show an age-related depletion of neurofilaments and an increased ratio of microtubules/neurofilaments. By contrast, the preserved dorsal root axons of NF-M–null mutant animals do not show a similar depletion of neurofilaments. Thus, the lack of an NF-M subunit renders some axons selectively vulnerable to an age-dependent atrophic process. These studies argue that neurofilaments are necessary for the structural maintenance of some populations of axons during aging and that the NF-M subunit is especially critical.
The anti-apoptotic activity of XIAP is retained upon mutation of both the caspase 3– and caspase 9–interacting sites
Authors: Silke John , Hawkins Christine J. , Ekert Paul G. , Chew Joanne , Day Catherine L. , Pakusch Miha , Verhagen Anne M. , Vaux David L.
Published: July 2002

The X-linked mammalian inhibitor of apoptosis protein (XIAP) has been shown to bind several partners. These partners include caspase 3, caspase 9, DIABLO/Smac, HtrA2/Omi, TAB1, the bone morphogenetic protein receptor, and a presumptive E2 ubiquitin-conjugating enzyme. In addition, we show here that XIAP can bind to itself. To determine which of these interactions are required for it to inhibit apoptosis, we generated point mutant XIAP proteins and correlated their ability to bind other proteins with their ability to inhibit apoptosis. ∂RING point mutants of XIAP were as competent as their full-length counterparts in inhibiting apoptosis, although impaired in their ability to oligomerize with full-length XIAP. Triple point mutants, unable to bind caspase 9, caspase 3, and DIABLO/HtrA2/Omi, were completely ineffectual in inhibiting apoptosis. However, point mutants that had lost the ability to inhibit caspase 9 and caspase 3 but retained the ability to inhibit DIABLO were still able to inhibit apoptosis, demonstrating that IAP antagonism is required for apoptosis to proceed following UV irradiation.
Distinct Costimulatory Molecules Are Required for the Induction of Effector and Memory Cytotoxic T Lymphocytes
Authors: Liu Yang , Wenger Roland H. , Zhao Min , Nielsen Peter J.
Published: July 2002

A successful T cell immune response has two major products: effector T cells which directly or indirectly remove the antigens, and memory T cells, which allow a faster and more efficient recall response when challenged by related antigens. An important issue is whether costimulatory molecules on the antigen-presenting cells are involved in determining whether T cells will differentiate into effector or memory cells after antigenic stimulation. To address this issue, we have produced mice with targeted mutations of either the heat-stable antigen (HSA), or both HSA and CD28. We show that CD28/B7 and HSA provide two alternative costimulatory pathways for induction of immunological memory to influenza virus. Furthermore, our results revealed that B7 is essential for the generation of effector T cells from either naive or memory T cells, while HSA is not necessary for the generation of effector T cells. Our results demonstrate that the induction of memory T cells and effector T cells can utilize distinct costimulatory molecules. These results have important implications on lineage relationship between effector and memory T cells.
Association of Phosphorylated Serine/Arginine (SR) Splicing Factors With The U1–Small Ribonucleoprotein (snRNP) Autoantigen Complex Accompanies Apoptotic Cell Death
Authors: Utz Paul J. , Hottelet Maria , van Venrooij Walther J. , Anderson Paul
Published: July 2002

Proteins subject to proteolysis or phosphorylation during apoptosis are commonly precipitated by autoantibodies found in the serum of patients with systemic lupus erythematosus (SLE). We screened a panel of murine monoclonal and human monospecific sera reactive with known autoantigens for their ability to selectively precipitate phosphoproteins from apoptotic Jurkat T cell lysates. Sera known to recognize the U1–small nuclear ribonucleoprotein (snRNP) complex (confirmed by their ability to precipitate U1–snRNA) selectively precipitated a phosphoprotein complex (pp54, pp42, pp34, and pp23) from apoptotic lysates. Monoclonal antibodies reactive with U1–snRNP proteins precipitated the same phosphoprotein complex from apoptotic lysates. The phosphorylation and/or recruitment of these proteins to the U1–snRNP complex is induced by multiple apoptotic stimuli (e.g., Fas ligation, gamma irradiation, or UV irradiation), and is blocked by overexpression of bcl-2. The U1–snRNP-associated phosphoprotein complex is immunoprecipitated by monoclonal antibodies reactive with serine/arginine (SR) proteins that comprise a structurally related family of splicing factors. The association of phosphorylated SR proteins with the U1–snRNP complex in cells undergoing apoptosis suggests a mechanism for regulation of alternative splicing of apoptotic effector molecules.
Interferons Regulate the Phenotype of  Wild-type and Mutant Herpes Simplex Viruses In Vivo
Authors: Leib David A. , Harrison Travis E. , Laslo Kathleen M. , Machalek Michael A. , Moorman Nathaniel J. , Virgin Herbert W.
Published: July 2002

Mechanisms responsible for neuroattenuation of herpes simplex virus (HSV) have been defined previously by studies of mutant viruses in cultured cells. The hypothesis that null mutations in host genes can override the attenuated phenotype of null mutations in certain viral genes was tested. Mutants such as those in infected cell protein (ICP) 0, thymidine kinase, ribonucleotide reductase, virion host shutoff, and ICP34.5 are reduced in their capacity to replicate in nondividing cells in culture and in vivo. The replication of these viruses was examined in eyes and trigeminal ganglia for 1–7 d after corneal inoculation in mice with null mutations (−/−) in interferon receptors (IFNR) for type I IFNs (IFN-α/βR), type II IFN (IFN-γR), and both type I and type II IFNs (IFN-α/β/γR). Viral titers in eyes and ganglia of IFN-γR−/− mice were not significantly different from congenic controls. However, in IFN-α/βR−/− or IFN-α/β/γR−/− mice, growth of all mutants, including those with significantly impaired growth in cell culture, was enhanced by up to 1,000-fold in eyes and trigeminal ganglia. Blepharitis and clinical signs of infection were evident in IFN-α/βR−/− and IFN-α/β/γR−/− but not control mice for all viruses. Also, IFNs were shown to significantly reduce productive infection of, and spread from intact, but not scarified, corneas. Particularly striking was restoration of near-normal trigeminal ganglion replication and neurovirulence of an ICP34.5 mutant in IFN-α/βR−/− mice. These data show that IFNs play a major role in limiting mutant and wild-type HSV replication in the cornea and in the nervous system. In addition, the in vivo target of ICP34.5 may be host IFN responses. These experiments demonstrate an unsuspected role for host factors in defining the phenotypes of some HSV mutants in vivo. The phenotypes of mutant viruses therefore cannot be interpreted based solely upon studies in cell culture but must be considered carefully in the context of host factors that may define the in vivo phenotype.
Selection at Multiple Checkpoints Focuses VH12 B Cell Differentiation toward a Single B-1 Cell Specificity
Authors: Tatu Calin , Ye Jian , Arnold Larry W. , Clarke Stephen H.
Published: July 2002

Phosphatidyl choline (PtC)-specific B cells segregate to the B-1 subset, where they comprise up to 10% of the B-1 repertoire. About half express VH12 and Vκ4/5H and are restricted in VHCDR3. We have previously reported that anti-PtC VHCDR3 is enriched among VH12-expressing cells by selective elimination of pre-B cells. We report here a bias for Vκ4/5H expression among VH12-expressing B cells, even among those that do not bind PtC and are not B-1. This is due in part to an inability of VH12 to associate with many light (L) chains but must also be due to a selective advantage in survival or clonal expansion in the periphery for Vκ4/5H-expressing cells. Thus, the bias for Vκ4/5H expression is independent of PtC binding, and, as segregation to B-1 occurs after Ig gene expression, it precedes segregation to the B-1 subset. In 6-1 mice, splenic B-1 cells reside in follicles but segregate to follicles distinct from those that contain B-2 cells. These data indicate that selection at multiple developmental checkpoints ensures the co-expression of an anti-PtC VHCDR3 and L chain in a high frequency of VH12 B cells. This focus toward specificity for PtC facilitates the development of a large anti-PtC B-1 repertoire.
How Mira Variables Change Visual Light by a Thousandfold
Authors: Reid M. J. , Peek J. E. G.
Published: July 2002

Mira variables change visual light by up to 8 mag over their roughly yearly cycle. Here we present a simple explanation for the extremely large amplitudes of light curves of oxygen-rich Mira variables. Metallic oxides, such as TiO, form throughout the stellar atmosphere as the star cools when approaching minimum light. When this happens, the visual light can be almost completely absorbed at large radii, extending the visual photosphere to nearly twice its nominal size. At these large radii, temperatures can fall to ≈1400 K and essentially all of the star's radiation emerges in the infrared. Since almost no optical light is emitted at these low temperatures, Mira variables can decrease their visual light by more than a thousandfold and almost "disappear" to the human eye.
Ion optics of mass spectrometers I. Electrostatic fields
Authors: B S Prahallada Rao
Published: July 2002

The ion-optical properties of the radial electrostatic field analyser have been studied by several workers and appear mainly in the form of mathematical formulae. In this paper some of these properties are re-examined and are presented graphically over ranges of values of several parameters. This should be helpful when selecting values of these parameters for a design.
The measurement of the elastic constants of four alkali halides
Authors: S Hart
Published: July 2002

Discrepancies of up to 10% exist in the published values of the elastic constants of alkali halides and these are too large to be accounted for by individual experimental errors. Static, resonance and ultrasonic techniques have been applied to the determination of the elastic constants of LiF, NaF, NaCl and KCl at room temperature. All the specimens of each material were taken from the same parent single crystal which was grown by the Stockbarger method.

Close agreement was obtained with the three methods, indicating that the discrepancies which do exist in the published data may be due to differences in the single crystals used by the various investigators.
Triggering of a pressurized spark gap by a laser beam
Authors: F Deutsch
Published: July 2002

A delay line was discharged into a terminating resistor by a spark gap of coaxial design. The spark gap was triggered by a focused laser beam, introduced along the axis; a Q-switched ruby laser giving pulses of 20 ns duration and up to 50 MW power was used.

The range of operation of the gap, formative time of the breakdown and jitter were investigated for different gases at pressures above atmospheric, gap widths of 4-10 mm and voltages of up to 120 kv. Mixtures of argon and nitrogen were found to have certain advantages, such as a low threshold for ionization by the laser beam, sufficient dielectric strength, low values of the formative-time jitter and chemical inertness.

Formative times of down to about 1 ns and jitters below 1 ns were found. The laser power can be relatively low (0·5-5 MW). An explanation for the breakdown mechanism is proposed.
Precious metal alloys for high-temperature resistance strain gauges
Authors: R Bertodo
Published: July 2002

Much work has been carried out over the years in an attempt to develop a gauge for the measurement of steady strains up to 1000°C. As a result satisfactory elements exist for use up to 300°C; over the range 300-1000°C alloys of Pt and W were shown to be suitable in 1963. Since that date a number of discrepancies have come to light.

The present paper reviews earlier work on precious metals and their alloys and examines in detail the behaviour of some platinum metals and alloys exposed to oxidizing atmospheres for extended periods of time. Preliminary work aimed at obtaining more satisfactory alloys for use at extreme temperatures is outlined.

It is concluded that the apparently anomalous behaviour of some samples of Pt-W is associated with the metallurgical state of the alloy. On the basis of preliminary test results an alloy of Pt, Pd and Mo is shown to be superior to Pt-W for steady strain element manufacture.
Condensation pumping of hydrogen and deuterium on to liquid-helium-cooled surfaces
Authors: J N Chubb  , L Gowland  , I E Pollard
Published: July 2002

The condensation of hydrogen and deuterium on to liquid-helium-cooled surfaces is being studied for high-efficiency contamination-free pumping applications in plasma physics experiments.

The present experimental studies show that the sticking coefficient of hydrogen and deuterium at room temperature increases during initial coverage of a liquid-helium-cooled condensing surface from around 0·5 at about 1013 molecules cm−2 to between 0·7 and 0·95 at 1016 molecules cm−2, and then remains essentially independent of further coverage. The sticking coefficient tends to increase with increasing gas incidence rate, but is only susceptible to surface temperature at the higher end of the range 2·1-3·7°K for very low gas inflow rates.

During initial coverage of the condensing surface the desorption rate of gas molecules increases with surface coverage and reaches a steady value for coverages of about 3 × 1016 molecules cm−2. This desorption rate does not decrease as rapidly with surface temperature as expected from published hydrogen and deuterium vapour-pressure curves. Experiments show that this is due to thermal-radiation desorption effects. The application of condensation pumping in practice to maintain gas densities below about 5 × 108 molecules cm−3 (about 10 ntorr) thus requires some restriction of the thermal-radiation loading at the condensing surface.
Reply to Comments of Lynch
Authors: W L V Price
Published: July 2002

The values for the principal dielectric constants of sapphire given in a
recent paper by W. L. V. Price appear to be influenced by a systematic error.
An evaluation of absorption correction functions for electron probe microanalysis
Authors: C A Andersen  , D B Wittry
Published: July 2002

The absorption correction function necessary to quantitative electron probe microanalysis has been studied experimentally by a number of authors. The experimental data of these groups are systematically reviewed here to determine their dependence on primary electron accelerating potentialE0, excitation potential ratioUand atomic numberZ. The data are compared by assuming that the mean depth of x-ray production IMG1 characterizes the distribution of x-ray emission with depth Φ(ρz) accurately enough to show the influence ofE0,UandZon the absorption correction function. Monte Carlo calculations are used to show that IMG1 can be described by a modified approximation to the Bethe electron retardation law. The experimental data are then compared, using this modified approximation to take account of the influence ofE0,UandZ. On this basis there is good agreement among the various data that do not have large errors. This agreement suggests the possibility of a correction function based on the method of comparison used. The proposed correction function is compared to a well-accepted correction model over large ranges ofE0,UandZ.
Valence band structure of SnTe
Authors: L M Rogers
Published: July 2002

Room-temperature electrical and thermal properties of p-type SnTe for the carrier concentration range 4 × 1019-2 × 1021 cm−3 have been quantitatively explained using a two-valence-band model in which the principal light mass band is always highly non-parabolic and the heavy mass band is parabolic. Band parameters of the model were determined. The theory was based on Cohen's dispersion law for energy surfaces with rotation plus reflection symmetry. The close similarity in band structure between SnTe and PbTe was established. It appeared that the 300°K band parameters of SnTe were very similar to the 0°K band parameters of PbTe, given by Rogers, but the energy separation between valence band edges was much greater in SnTe. Intravalley acoustic-mode lattice scattering was always dominant at room temperature.
Electron probe microanalysis of metal oxides: comparison of correction methods
Authors: C A Friskney  , C W Haworth
Published: July 2002

Several metal oxides have been analysed under constant time conditions, using pure metal standards. A vacuum-deposited coating of copper (100 Å thick) prevented electrostatic charging of the specimens and reduced heating effects. Eight different methods for applying absorption and atomic number corrections have been evaluated. A method due to Duncumb and co-workers is found to give the best results, the relative error in the analysis being in general less than 5 per cent.
The entry of aerosols into sampling tubes and heads
Authors: C N Davies
Published: July 2002

No general solution exists of the very complicated problem of aerosol sampling. In this paper the problem is broken down into sampling with a thin-walled tube and sampling with a bulky head. Tube sampling can be classified into `small tubes', which give the same results independent of their orientation, and `large tubes' where there is a change of sampling efficiency when the direction of the tube is altered.

The limits of radius of a `small tube' sampling with an efficiency near to 100% are laid down in terms of particle size and suction speed; tables are given for evaluating the sampling efficiency in a wind. Calm air is defined by the wind speed being less than a value which is dependent on the sampling speed and particle size.

The sampling efficiency of a `large tube' may depend on its orientation owing to the fall of particles due to gravity or to a wind blowing past the tube. Isokinetic sampling is necessary to obtain correct samples in strong winds; the effect on efficiency of sampling due to departure from the isokinetic conditions is discussed.

The conditions are deduced for accurate sampling with a bulky suction head containing a small orifice: if the orifice faces downwards a critical suction speed exists below which no sample is obtained; at higher speeds sampling is selective and depends on the falling speed of the particles.

When a bulky head is used in a cross wind there is no effect due to wind when the orifice is in the top. For a downwards facing orifice the effect of wind is to cause sampling to start at a lower rate of suction and to be more efficient at lower rates of suction. At high rates of suction the wind has no effect.
Flux jumping phenomena in sputtered cylindrical niobium films
Authors: P Hlawiczka  , J M Ross
Published: July 2002

Measurements of the critical temperature and resistance ratio of cylindrical niobium films, prepared by getter sputtering, indicate that their purity is high. Magnetic measurements on the superconducting films show that flux penetrates to the bore of the cylinder, either in the form of regular jumps or continuously, in a manner resulting in regular hysteresis. The variation of the magnitude of the jumps with applied field and temperature is reported, and the magnitude is also found to be proportional to the square root of film thickness. The latter result is also obtained from a thermodynamic energy balance calculation, but predictions of the flux jump height as a function of the applied field and temperature yield only partial agreement with experiment.
Non-linear mechanical response of various metals. II. Permanent length changes in twisted tubes
Authors: E W Billington
Published: July 2002

For pt.I see ibid., vol.10, no.4, p.519 (1977). The Swift (1947) effect, observed here as the permanent lengthening of a tubular specimen along the principal axis about which it is being examined. Permanent length changes in twisted tubes are considered in relation to the Poynting effect and incremental theories of plasticity. It is shown that the increasing body of experimental evidence, including the present measurements on aluminium, copper, iron and an aluminium alloy, cannot be accounted for by an incremental theory of plasticity which assumes incompressibility and interprets the displacement gradients in terms of small strain components. This is considered to arise from the fact that incremental theories based on small strain components do not consider a component of axial strain which is entirely geometric in origin, an observation which is independent of whether the twisted tube is to be regarded as isotropic or anisotropic. Satisfactory correlation of the observed length changes of twisted tubes with the shear strain is obtained with an incremental-type constitutive equation for an isotropic incompressible strain-hardening elastic-plastic solid with large deformation.
The effect of neutron energy dependence and anisotropic scattering on the linear extrapolation distance of a black sphere. II. Numerical examples
Authors: A K Prinja  , M M R Williams
Published: July 2002

For pt.I see ibid., vol.7, p.2174 (1974). The authors consider the diffusion of neutrons in an infinite non-absorbing medium, in which is embedded a black sphere. A numerical study of the extrapolation distance for the sphere has been carried out using the variational method. The effects of energy-dependent cross-sections and linear anisotropy of scattering have been included. It is found that, when scaled in units of the Maxwellian averaged mean free path, the effect of energy dependence leads to differences of about 1% in the value of the extrapolation distance when compared with the one-speed values. The effect of linear anisotropy of scattering is included and evaluated numerically in the one-speed case by means of a novel, non-variational method.
The energy dependence of a diffusion model of an electron probe into solid targets
Authors: K Kanaya  , S Ono
Published: July 2002

The penetration and energy loss characteristics of an electron probe with energies 1 and 103keV in solid targets are analysed by using the potential function of the power and exponential forms of the potential function with a screened atomic radius for scatterings. Then, the diffusion effect due to multiple collisions is combined with the energy retardation in accordance with a modified Thomson-Whiddington law, with the scattering cross-section in the Lenard absorption law, to give consistent expressions for the variation of the transmission fraction eta T and back-scattering fraction eta B with depth y=x/R together with the diffusion depth yDand the maximum energy loss depth yEnormalised by the penetration range R as a function of the parameter gamma (which is a function of the incident energy and the atomic number). Diffusion is considered to take place through a hemisphere with a centre located at the most probable energy dissipation depth yC, related to the diffusion depth YD.
Observation of high-temperature electron injection in dense argon and mercury: application to cathode spots
Authors: A Leycuras
Published: July 2002

Presents experimental results which show that a wall in contact with a dense hot metal vapour injects a very-high-density current. In the same way, at the root of a cathode spot the vapour density is very high and a calculation is made of the enhancement of the electron emission due to the lowering of the work-function caused by the polarisation energy of the excess electrons in the vapour. A relation is established which allows the density of the vapour to be determined and thus the rate of evaporation of a cathode made out of any material.
On the applicability of the Druyvesteyn method of measuring electron energy distributions
Authors: J E Allen
Published: July 2002

It is pointed out that Druyvesteyn's method (1930) is applicable to isotropic distribution functions.
Negative ions in Trichel corona in carbon dioxide and oxygen
Authors: P S Gardiner  , J L Moruzzi  , J D Craggs
Published: July 2002

The negative ions in Trichel corona (negative point/plane geometry) in CO2and O2have been identified and their times of flight in the discharge gap have been measured. The results confirm previously held qualitative views of the mechanism of Trichel corona.
A study of gold/n-InP contacts
Authors: D V Morgan  , M J Howes  , W J Devlin
Published: July 2002

Two types of device have been fabricated, a heated surface and an unheated surface. For heated surface devices the barrier heights measured by a variety of techniques are consistent with each other and with the results reported by other workers. Unheated devices, however, exhibit inconsistencies which are attributed to an interfacial oxide film.
Characteristics of a corona system under negative direct and pulsed voltage
Authors: L C Thanh
Published: July 2002

The characteristics of a clean electrode system energised in clean atmospheric air are studied when the applied voltage is negative direct and negative pulsed respectively. The discharge patterns along the wire electrode are measured by means of an optical system which includes a photomultiplier. A linear relationship is found to exist between the average photon current and the corona current. When the photon currents are the same, the discharge patterns are similar for both types of applied voltage. The Trichel current waveshapes are also similar at low voltage levels. However, at high pulsed voltage values, the Trichel current amplitude and frequency are affected by the space charge conditions.
Metastable effects associated with the reflection of a pressure pulse at the free surface of water
Authors: H N V Temperley  , D H Trevena
Published: July 2002

Evidence is now brought forward to show that the reflection of evan a small amplitude pressure pulse at a free surface is accompanied by considerable distortion. An explanation of this fact, and of the low values of tensile strength of water inferred from underwater explosion and similar 'once only' pulses, is suggested in the light of existing ideas about the structure of a liquid surface. It is concluded that there is now no real disagreement between experiment and theory on tensile strength as there are now acceptable explanations of the low values found from ultrasonic and 'once only' pulse methods.
An experimental method for studying thermal diffusion in mixtures containing the adsorbable gas Rn
Authors: A Pazdur
Published: July 2002

An experiment has been constructed for studying thermal diffusion in the binary mixture222Rn-CO2by means of the two-bulb method. A smaller thermodiffusional chamber has been constructed as a proportional counter to facilitate the continuous monitoring of the222Rn concentration during the whole measurement. A difference method has been used for determining the steady-state separation factor in order to eliminate the effects of the adsorption of radon on the walls of the apparatus. The thermal diffusion factor alphaThas been measured at the temperature T=338.8K.
A metal-seeded rotating plasma
Authors: G F Brand  , B W James  , C J Walsh
Published: July 2002

The motion of metal introduced from an arc into a rotating plasma has been followed spectroscopically. The experimental observations agree well with a theory in which the metal is evaporated from the cathode in aggregate of about 100 particles.
The orientation dependence of measured inelastic scattering probabilities for fast electrons in single crystals
Authors: C J Rossouw  , M J Whelan
Published: July 2002

When a well-collimated beam of high-energy electrons traverses a thin single-crystal specimen (as in transmission electron microscopy), an inelastic event may induce an angular spread in the inelastic beam, effectively reducing collimation. Calculation of the 'smeared out' diffraction contrast preserved in the inelastic beam indicates that measured mean free paths for discrete excitations may alter with diffraction conditions. Theory is correlated with experimental observations for plasmon and nitrogen K-loss signals from single-crystal aluminium nitride platelets. These results enable favourable diffraction conditions for quantitative microanalysis of single crystals by electron energy-loss spectrometry to be defined.
Interferometric determination of electron density in a high pressure hydrogen arc. I. Calculation of refraction index
Authors: R Radtke  , K Gunther  , R Ulbricht
Published: July 2002

The refraction index of a hydrogen plasma in LTE was calculated as a function of the wavelength of observation, temperature and pressure, taking into account bound-bound and bound-free transitions of the neutral atom. According to the author's calculations, the influence of excited states at higher temperatures is smaller than indicated by Baum and co-workers (1975) for argon. Using the calculations presented here, the interferometric investigation of a high pressure hydrogen arc should allow the determination of the electron density with an accuracy of the order of 1%.
Resonant system of a torsion pendulum with anelastic solids of discrete relaxation spectra
Authors: Y Iwasaki  , K Fujimoto
Published: July 2002

An anelastic solid of discrete relaxation spectra, called a general linear solid is considered to be a single Voigt solid. A torsion pendulum with a specimen exhibiting the characteristics of a general linear solid is shown to oscillate according to the equation of motion Id2theta /dt2+ nu d theta /dt+k theta =0, by expressing the equation in the equivalent complex notation. Introducing this complex expression in the mechanical analysis of the torsion pendulum, facilitates the derivation of the formulae of frequency and internal friction especially in the case of a Collette torsion pendulum.
Coke breakage behaviour in relation to its structure
Authors: T J Peirce  , A E Horton  , J Tucker
Published: July 2002

Coke for blast-furnace use must meet specified quality criteria as defined in terms of its measured breakage characteristics in a revolving flew drum. An assessment of the relationship between coke macrostructure and volumetric (coarse) breakage behaviour is made and the manner in which both features are affected by the coal charge composition is made. In particular, coke degradation studies have revealed a heterogeneous pattern of volumetric breakage in so far as: (i) coke pieces which are extensively fissured fail spontaneously after only a few revolutions in the drum; (ii) coke pieces which are less fissured require an extended treatment in the drum and finally fail in a manner consistent with that of fatigue crack growth induced by repeated impact. This heterogeneity in breakage behaviour was demonstrated in terms of an abrupt change in gradient of the Weibull distribution function for the coke. Heterogeneity may be removed by fully stabilising the coke or by the use of a more energetic test method. The role of fatigue crack growth in coke breakage was studied.
Some features of the structure of metallurgical cokes and their effects on strength
Authors: G J Pitt  , J C V Rumsey
Published: July 2002

Five theoretical models relating strength to total pore volume are fitted to the experimental data for seven cokes and the goodness of fit is compared. Estimates of zero-porosity strength are obtained by extrapolation and are compared with alternative estimates obtained by fracturing small ( approximately 0.1 mm) coke particles containing only 5% of pores. Predictions of the surface area of the microfissures formed when some constituents of coke contract around non-contracting particle constituents during the coke formation process are compared with experimental results obtained by microscopy.
A critical appraisal of some recent correction procedures for quantitative electron-probe microanalysis
Authors: G Love  , V D Scott
Published: July 2002

Four recent correction procedures for quantitative electron-probe microanalysis are evaluated using light element (Z<10) results as well as heavier element data. In the light element range the Ruste-Zeller (1977) and Love-Scott (1978) models are superior to the established correction procedure. For quantitative analysis of heavier elements only the Love-Scott model performed better than the established method, the procedures of Ruste-Zeller, Anderson-Wittry (1968) and Parobek-Brown (1978) giving similar results. The construction of the respective models are discussed and suggestions made for their improvement.
On the reliability of temperature estimation from bremsstrahlung emissions for a high-Z, laser-produced plasma
Authors: B K Sinha
Published: July 2002

Relative contributions of recombination, bremsstrahlung and line emissions from an aluminium plasma produced by a laser have been calculated using a steady-state corona model for the ionisation state. Intensity ratios, through aluminised polycarbonate foils of different thicknesses, have been calculated to estimate the electron temperature of the plasma at temperatures of 50 eV-5 keV. Except at very high temperatures in the keV regime, the contribution due to bremsstrahlung can be very well ignored and the X-ray emission can be taken as pure recombination. Contribution due to line emission was found to be negligible at all temperatures, in the given spectral region, even through one thin foil. It was found to be erroneous to estimate the electron temperature from bremsstrahlung emissions even when a choice of transmission bands, away from and between the recombination edges, is made according to the existing methods.
Cavitation experiments using a water shock tube
Authors: B E Richards  , D H Trevena  , D H Edwards
Published: July 2002

A new method of generating a tension pulse in a liquid column is described. The test liquid (deionised water) is contained in the lower part of a sealed vertical tube, the upper part of which contains a combustible gaseous mixture. When a detonation wave is initiated in the gas it is propagated down the liquid column as a compressional wave. At the base of the column, which is supported by a thin Mylar diaphragm, this pulse is reflected as an upward-going tension pulse. The pressure changes in the liquid are monitored by pressure transducers mounted in the wall of the tube and the cavitation bubbles are studied using schlieren photography techniques. The measured value of the breaking tension agrees well with those of other dynamic methods.
The rapid measurement of approximate flow velocities in an internal combustion engine using photon correlation laser anemometry
Authors: J B Cole  , M D Swords
Published: July 2002

A method has been developed which allows rapid estimates to be made of flow velocities in a spark ignition engine. The information obtained from the laser-Doppler anemometry facility was processed using an original algorithm to extract mean velocities from individual cycles. The results indicated that most of the turbulence in the engine studied consists of relatively large-scale, low-frequency fluctuations which are conventionally interpreted as cyclic differences in mean velocity. These large flow structures also have the dominant effect in the generation of cyclic variations of combustion efficiency.
Attachment, detachment and ion-molecule reactions in SO2and SO2-O2mixtures
Authors: V K Lakdawala  , J L Moruzzi
Published: July 2002

A pulsed drift tube has been employed for measurement of the electron attachment coefficient, alphaain pure sulphur dioxide over the E/N range 3.03<or=E/N<or=242.4 Td. A pressure dependence of alphaa/(SO2) has been observed for E/N<40.0 Td, indicating the existence of a three-body attachment process, whilst for values of E/N>40 Td the results indicate a dissociative attachment process. Measurements of the mobility of the negative ions formed indicate the presence of at least four ions with reduced mobilities of 0.69, 0.62, 0.55 and 0.39 cm2V-1s-1respectively. Using a drift tube mass spectrometer system the ion spectra produced in pure SO2and in SO2-O2mixtures have been studied. In pure SO2at pressures around 1 Torr a number of large cluster ions are observed. At much lower pressures the predominant ion is SO2-which rapidly clusters to form SO2.SO2-as the pressure increases. When SO2is added to oxygen the following reactions are observed: O-+SO2to SO3+e; O2-+SO2to SO2-+O2. The rate for the first reaction has been measured over a range of E/N and has been found to vary between 2.0*10-9cm3s-1and 8*10-10cm3s-1. The second reaction has a rate of 3.9*10-9cm3s-1at E/N=117.2 Td.
Thermally stimulated conductivity in InP:Fe
Authors: M C Petty  , T M McGinnity
Published: July 2002

An investigation of thermally stimulated conductivity (TSC) for InP:Fe is reported. The magnitude of the observed TSC signal is discovered to be critically dependent upon the nature of the electrical contacts to the sample. Using a variety of analysis techniques, two main traps are found in the material with activation energies of approximately 0.25 eV and 0.50 eV. The ability to fill the deeper level depends on the illumination temperature and it is suggested that this might be explained by a temperature variation in the capture cross-section.
Thermomagnetic studies of conversion of pyrite and marcasite in different atmospheres (vacuum, H2, He and CO)
Authors: M S Jagadeesh  , M S Seehra
Published: July 2002

The results of a study of the conversion of pyrite (obtained from coal) and marcasite, when heated to about 485 degrees C in several different atmospheres (vacuum, He, H2and CO) are reported. Changes in the magnetic susceptibility chi and in the mass of the sample are noted as the sample is first heated to 485 degrees C and then cooled to room temperature at the rate of about 2 degrees C min-1. The composition parameter chi of the converted pyrohotites Fe1-xS is determined from the known location of the various magnetic and structural transitions in Fe1-xS and from the magnitudes of the observed chi . The mass changes indicated the conversion process FeS2to Fe1-xS. Pyrite, when heated in vacuum and He, forms monoclinic pyrohotites with x approximately 0.11 to 0.13 whereas in H2atmosphere it converts to hexagonal pyrohotites with x approximately 0.08 to 0.10. Prolonged heating in H2eventually produces FeS (x=0). In CO atmosphere the end product seems to be an antiferromagnetic pyrrhotite with x approximately 0.05. For marcasite, the conversion products in vacuum and H2atmospheres are essentially the same as that for pyrite except that the conversion efficiencies are somewhat higher. The magnetic properties of coal pyrites vis-a-vis mineralogical pyrites are also examined.
Optical design for a streamer chamber in a quark search experiment
Authors: P Lecoq  , C Marrian  , F Rohrbach
Published: July 2002

The design of an optical system for a streamer chamber, working in the avalanche mode, which will be used in an experiment searching for fractionally charged particles (CERN 1977), is presented and evaluated. The ability of the optical system and chamber to detect fractionally charged quarks by a measurement of their specific primary ionisation has been investigated by a study of tracks of charged particles obtained in various gases in a small test chamber and a simulation of avalanche formation and detection. The first results obtained in the full size chamber are also presented.
Double layer formation in a magnetised laboratory plasma
Authors: D Andersson
Published: July 2002

Double layers in a current-carrying magnetised argon plasma are studied experimentally. The layer evolves from an unstable anode sheath when the anode voltage has reached a critical value which depends on the neutral gas pressure. The double layer is an oscillating, three-dimensional structure enclosing both axially and radially a plasma at higher potential which is maintained by a low rate of ionisation due to the accelerated electrons. Axially accelerated electrons and radially accelerated ions have been detected, but not axially accelerated ions. High frequency is detected on the anode side of the layer. Double layers have also been observed in helium and xenon plasmas. Time independent numerical solutions of Maxwell's equation div D= rho in one dimension including ionisation are discussed.