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The front-illuminated charge-coupled device (CCD) detectors in the Chandra X-ray Observatory's ACIS instrument suffered radiation damage from soft protons focused by the telescope mirror early in the mission. In the course of assessing this damage, the focal plane was temporarily warmed from its normal operating temperature (then -100/spl deg/C) to +30/spl deg/C. Following this "bakeout", the radiation-damaged CCDs exhibited significantly greater charge transfer inefficiency (CTI). We performed a laboratory experiment with a sibling of the flight detectors in an attempt to reproduce and better understand this phenomenon. The test CCD was cooled to -100/spl deg/C, irradiated by 120 keV protons and then warmed to +30/spl deg/C for 8 hours. As expected, after the initial irradiation, but before detector warmup, a substantial CTI increase was observed. The subsequent warmup itself then produced an additional factor /spl ap/2.5 increase in CTI. Following smaller subsequent irradiations with the detector cold, a "bakeout" for 8 hours at -60/spl deg/C produced no observable increase in CTI. However, a subsequent bakeout to +30/spl deg/C for another 8 hours resulted in an additional increase in CTI of roughly 15%. The CTI changes produced by the room temperature bakeout are accompanied by dramatic changes in the de-trapping times of electron traps responsible for the CTI. The distributions of signal amplitudes in the pixels trailing X-ray events indicate that annealing at room temperature can cause large changes of the trap emission times, from which we infer that conversion of trapping defects takes place. The observed phenomena can be explained by the previously suggested mechanism of carbon-related defect transformation. Specifically, the room-temperature annealing may allow carbon interstitials to form metastable complexes with phosphorus and/or carbon substitutional atoms.

Laser surface treatment of metals is a process in which heating or melting of the surface of the metal by laser irradiation is followed by a rapid cooling via self-quenching. This process can produce metallurgical structures with improved wear and corrosion resistance. For zirconium alloys, laser melting (glazing) has been used to modify the microstructure of the surface layers of Zircaloy-2 and -4 tubing, and Zr-2.5Nb pressure tube alloy (1-4) without affecting the bulk properties. A supersaturated [alpha][prime]-martensitic structure was produced by the laser-glazing process. In addition, laser glazing produced a rough surface finish, which was attributed to rippling effects during the rapid solidification. In the present work the authors have investigated laser surface heating because such a treatment is expected to produce a similar microstructure as laser glazing, but with a better surface finish. Laser irradiation could raise the specimen's surface temperature into the [beta]-phase region and the subsequent rapid cooling should be sufficient to achieve the martensitic phase transformation, without requiring surface melting. The microstructure produced by laser surface heating was characterized by transmission electron microscopy. The depth profiles of the laser surface heated layers were obtained using microindentation. This paper reports the results obtained in this investigationmore » of microstructural changes produced in the surface layers of Zr-2.5Nb alloy by laser surface heating.« less

A three dimensional numerical model has been developed to calculate the transient temperature field during the laser transformation hardening of metal surfaces. The model takes into account the finite dimensions of the substrate, the temperature dependence of the physical properties, the laser scanning velocity, and the surface heat loss through convection and radiation. The model is used to predict the temperature distribution in the substrate and the phase transformation depth resulting from the laser surface treatment. Good agreement is demonstrated with experimental results for the laser hardening of a zirconium alloy.MST/1867

A prototype on-line rotor temperature monitor based on phosphor decay-time measurements using optical fibers was tested on two large electrical generators.

After launch, the Advanced CCD Imaging Spectrometer (ACIS), a focal plane instrument on the Chandra X-ray Observatory, suffered radiation damage from exposure to soft protons during passages through the Earth's radiation belts. An effect of the damage was to increase the charge transfer inefficiency (CTI) of the front illuminated CCDs. As part of the initial damage assessment, the focal plane was warmed from the operating temperature of -100C to +30C which unexpectedly further increased the CTI. We report results of ACIS CCD irradiation experiments in the lab aimed at better understanding this reverse annealing process. Six CCDs were irradiated cold by protons ranging in energy from 100 keV to 400 keV, and then subjected to simulated bakeouts in one of three annealing cycles. We present results of these lab experiments, compare them to our previous experiences on the ground and in flight, and derive limits on the annealing time constants., 9 pages, to appear in Proc. SPIE 7021, "High Energy, Optical and Infrared Detectors for Astronomy"

Experimental data have been generated for the bead‐on‐plate keyhole welding of mild steel using the TEM 00 beam from a 1.5 kW CO2 laser and a range of material thickness from 0.64 to 2.6 mm. For each thickness, the maximum welding speed was measured for laser powers from 600 to 1500 W, using the criterion of full penetration along a 5 cm length. Analysis of the data has yielded a simple correlation between laser power (P,kW), penetration depth (d,cm) and welding speed (v,cm/s). When the specific welding energy per unit thickness (Pd−1v−1) is plotted against welding speed (v), the data are observed to lie on a single curve. An analytical expression of this relationship has been derived for speeds above 1 cm/s: P=3.83d + 0.69dv (1≤v

This chapter covers the traditional breeding of apples, natural and induced variation in the crop and the apple breeding programmes in 31 countries from around the world. Notes are presented on the breeding of apples for disease resistance, improved quality and nutrient contents, and reduced flesh browning and allergenicity. The use of genetic markers for the selection of crops with improved traits, as well as the use of biotechnology in the improvement of the crop are discussed.

Volatile organic compounds (VOCs) within new and established buildings have been determined and factors significant to their presence have been identified. In established dwellings, total volatile organic compound (TVOC) concentrations were low, but were approximately four times higher than in outdoor air, showing a dominant effect of indoor sources. The presence of attached garages, site contamination and 'faulty' wool carpet were associated with higher indoor pollution. In three dwellings, unidentified sources of benzene were indicated. Much higher VOC concentrations were observed in new or renovated buildings, persisting above "baseline" levels for several weeks, concentration decay rate correlating with VOC molecular volume, indicating emissions were limited by material diffusion processes. VOC and formaldehyde emission decays in a new dwelling occurred by a double-exponential source model. This shows that persistent low levels of volatile organic pollutants in established dwellings can occur due to long-term emissions from building materials.

Genes from the biocontrol fungus Trichoderma atroviride encoding the antifungal proteins endochitinase or exochitinase (N-acetyl-beta-D-hexosaminidase) were inserted into 'Marshall McIntosh' apple singly and in combination. The genes were driven by a modified CaMV35S promoter. The resulting plants were screened for resistance to Venturia inaequalis, the causal agent of apple scab, and for effects of enzyme expression on growth. Disease resistance was correlated with the level of expression of either enzyme when expressed alone but exochitinase was less effective than endochitinase. The level of expression of endochitinase was negatively correlated with plant growth while exochitinase had no consistent effect on this character. Plants expressing both enzymes simultaneously were more resistant than plants expressing either single enzyme at the same level; analyses indicated that the two enzymes acted synergistically to reduce disease. Selected lines, especially one expressing low levels of endochitinase activity and moderate levels of exochitinase activity, were highly resistant in growth chamber trials and had negligible reduction in vigor relative to control plants. We believe that this is the first report of resistance in plants induced by expression of an N-acetylhexosaminidase and is the first report of in planta synergy between an exochitinase and an endochitinase.

The energy resolution degradation of the ACIS CCDs on board the Chandra X-ray Observatory has been under investigation since the effect was first recognized two months after launch. A series of laboratory CCD irradiations with electrons and protons have taken place, leading to the belief that low energy protons are responsible for the damage. In order to confirm this, an experiment has been devised to represent the flight experience of the ACIS CCDs, and the results to date are shown here.

Hemophilia A is caused by factor VIII deficiency that historically has been treated with either a cryoprecipitate fraction of serum or factor VIII concentrate. Recently, the availability of affinity isolated factor VIII (Monoclate) has allowed for a highly purified preparation for the chronic therapy of hemophilia A. This factor VIII preparation contains a trace quantity (less than 50 ng/100 I. U.) of mouse IgG. Immunoassays for the measurement of human IgG, IgM and IgE anti-mouse IgG antibody (HAMA) were developed and used to measure HAMA levels in hemophilia A patients undergoing chronic therapy with Monoclate in three different clinical studies. Natural antibodies to mouse IgG were observed in patient sera prior to Monoclate infusion. Data is presented demonstrating that induction of HAMA upon Monoclate treatment does not occur. The low level of mouse IgG contained in Monoclate appears to be below the threshold of immunogenicity. Most importantly, clinical symptoms related to hypersensitivity or anaphylaxis were never observed in any patient undergoing chronic therapy with Monoclate in these clinical studies.

Experimental data have been generated for the bead-on-plate keyhole welding of mild steel using the TEM∞ beam from a 1.5 kW CO2 laser and a range of material thicknesses from 0.64 to 2.6 mm. For each thickness, the maximum welding speed was measured for laser powers from 600 to 1500 W, using the criterion of full penetration along a 5 cm length. Analysis of the data has yielded a simple correlation between laser power (P,kW), penetration depth (d,cm) and welding speed (v,cm/s). An analytical expression of this relationship has been derived for speeds from 1 to 16 cm/s. Stainless steel samples yield similar results. This correlation is interpreted in terms of the minimum energy envelope or range for laser welding as proposed by other workers and also in terms of the Swift-Hook and Gick theory of laser welding. Data on the effect of polarization are also presented and discussed in terms of the present correlation. Above a critical welding speed the welding efficiency is enhanced when the polarization of the laser beam is aligned with the direction of welding.Experimental data have been generated for the bead-on-plate keyhole welding of mild steel using the TEM∞ beam from a 1.5 kW CO2 laser and a range of material thicknesses from 0.64 to 2.6 mm. For each thickness, the maximum welding speed was measured for laser powers from 600 to 1500 W, using the criterion of full penetration along a 5 cm length. Analysis of the data has yielded a simple correlation between laser power (P,kW), penetration depth (d,cm) and welding speed (v,cm/s). An analytical expression of this relationship has been derived for speeds from 1 to 16 cm/s. Stainless steel samples yield similar results. This correlation is interpreted in terms of the minimum energy envelope or range for laser welding as proposed by other workers and also in terms of the Swift-Hook and Gick theory of laser welding. Data on the effect of polarization are also presented and discussed in terms of the present correlation. Above a critical welding speed the welding efficiency is enhanced when the polarization of the...

Operation of domestic smoke detectors (photoelectric and ionization) has been investigated in a typical Melbourne dwelling using smoke from smoldering hardboard and artificial smoke generated at three widely different rates. Detector performance was assessed according to the escape time offered by its operation, this being based on the criterion of visibility needed to effect escape. Under these test conditions detectors located in bedrooms performed adequately only when smoke originated in the same room; they provided poor escape times for smoke originating elsewhere. Also, ionization detectors usually provided adequate escape times only when smoke travel from the source room to the rest of the dwelling was restrained by small door openings, since it then took longer for visibility to be lost. Photoelectric detectors were generally more effective than ionization detectors, as expected for smoldering conditions, and when located in the hallway provided adequate escape times for most conditions of size and location of smoke source.

Extension of the British Standard Fire Propagation test (BS 476 Part 6) as a combustion mode for measuring smoke and toxic gas production from small panels of UPVC building products has been investigated. Hydrogen chloride gas concenatrations in the test room have been measured continuously with a method developed to ensure high collection efficiency from the fire gases. Using this method, the influences of test conditions (room temperature and humidity, room surface finish, reactivity of fire box interior) on HCl gas concentrations were examined to explain the fate of HCl gas after its evolution. The relative humidity (RH) in the room was the most critical factor influencing HCl gas concentrations during tests. Although HCl evolution early in the test was influenced little by RH and closely matched smoke production, maximum HCl gas concentrations in the room attained later varied markedly with RH. Generally, no more than one-third of the HCl expected theoretically remained airborne under any test condition. Further investigations suggested that this loss and the effect of RH are associated with HCl plate-out on room surfaces. Using test conditions set to minimize the influence of RH, HCl evolution from a series of UPVC building products was investigated. HCl concentrations in the test room did not exceed incapacitating levels for those products where less than a certain quantity of UPVC was combusted. This observation is discussed in relation to French regulations, which limit the total quantity of chlorine in some synthetic materials within building compartments.

No standard method has been developed for measureing the evolution of specific toxic gases from building lings when involved in fire. The British Fire Propagation test (BS 476 Part 6) operated in an instrumented room has been proposed for this purpose previously but has not found general acceptance. It is considered further in this report, which investigates the movement and measurement of smoke and specific fire gases under different conditions of room stirring and the effect of the latter on fire propagation indexes. Stiring has been found to have no statistically significant effect on fire propagation indexes provided that the effects of this on calibration of the apparatus are taken into account. Stirring also had little effect upon smoke production per se. Under unstire conditions smoke and toxic gases stratify in the same layer early in the test, and measurement of their production at any single room location will be subject to the location, the way the room influences stratification and how the room is instrumentee, as well as by the prpduct performance. Under stirred room conditions smoke and toxic gases are evenly distributed and product performance can be assessed more simply from concurrent measurements of fire, smoke and toxic gas parameters. The latter procedure is proposed for obtaining relative data on building linings and for examination in further studies for correlation to room and corridor burns.

Irradiation of natural isotopic abundance formaldehyde with a narrow linewidth ultraviolet laser has yielded high deuterium enrichments (>600 at 5 Torr, 303 K) at five wavelengths in the range 340 to 355 nm. The temperature and pressure dependence have been measured for both the enrichment and the selectivity, the latter being determined from high resolution spectra of deuterated and natural formaldehyde. In general, for the conditions investigated (293–343 K; 2–26 Torr), both selectivity and enrichment are decreasing functions of temperature and pressure, but in certain cases the selectivity is independent of pressure over a small range. The highest enrichment (1110) was measured at 2 Torr, 293 K, 352.061 nm. The results can be explained in terms of hot bands as well as Doppler broadening and pressure broadening of formaldehyde absorption bands. For all five high enrichment wavelengths, the enrichment is larger than the selectivity at low pressure (

A range of basic fillers has been incorporated into UPVC formulations and assessed for effectiveness in suppressing HCl evolution and influence on other fire properties. Investigations were carried out with the British Fire Propagation test (BS 476 Part 6) in a room previously used for assessing the fire behaviour of UPVC building products. HCl evolution was also studied following degradation in a pyrolysis tube furnace. Despite notable differences in these methods of assessment, good correlation was found between them. Varying degrees of HCl suppression were obtained and for formulations containing stronger bases effectiveness was found between them. Varying degrees of HCl suppression were obtained and for formulations containing stronger bases effectiveness was approximately stoichiometric to the amount of base present. Lithium hydroxide was thus the most effective HCl absorber on a weight basis. A formulation with 40 parts per hundred resin of this filler evolved only 2% of its theoretical HCl, although at the expense of increased fire propagation indexes. Smoke properties were not greatly influenced by the formulations. Precipitated calcite was considered the most promising acid-absorbing filler for practical use. At 40 parts per hundred resin it reduced HCl evolution to 34% of theoretical and markedly delayed the onset of incapacitating HCl concentrations in the room, with little influence on fire propagation properties of the UPVC.

An experimental study has been performed of the carbon-14 enrichment achievable in the ultraviolet laser dissociation of mixtures of14CH2O and12CH2O. The14C:12C enrichment factor in the CO product has been measured at 352.2 nm as a function of laser linewidth, formaldehyde temperature and pressure, and degree of carbon-14 depletion. The enrichment decreases with an increase in each of these parameters; the highest enrichment, 1190, was measured at 0.02 cm−1, 303 K, 1 Torr and a14C depletion of 10%. The results are assessed in terms of their application to radiocarbon dating, in particular for groundwater dating required for nuclear waste disposal, and to the enrichment of14C operating wastes extracted from nuclear reactors to a level suitable for commercial sale.

Samples of current Australian production of unplasticized polyvinyl chloride pipe and fitting materials have been examined in relation to combustion characteristics. Small scale laboratory assessment of piloted radiant ignition flame propagation and smoke generation have been investigated. Where necessary, improvements to methods of test or analysis of data have been developed and factors that influence results have been investigated. Piloted radiant ignititon and smoke production under flaming conditions are shfown to be the important combustion characteristics of UPVC materials for improvement.

The effects of the synthetic prostaglandin E1 analogue, rioprostil, on non-steroidal anti-inflammatory drug-induced (NSAID) gastritis are investigated. The study is of randomized, double-blind design. Patients are included who had classical or definite rheumatoid arthritis or osteoarthritis, had been taking a stable dose of NSAID or aspirin for at least one month and had endoscopically proven gastric lesion. Endoscopy is performed prior to, and at 4, 8 and 12 weeks of the treatment period. Patients receive either rioprostil, 300 micrograms or 100 micrograms q.d.s., or placebo q.d.s. The results of the endoscopies show greater healing of the mucosa in patients taking rioprostil compared with those taking placebo. It is therefore concluded that rioprostil is an effective compound for the management of patients with NSAID-induced gastritis.

The use of phosphor thermometry in generator rotor temperature monitoring over the 60-150 degrees C range has been investigated, using measurements of the decay time of the visible emission stimulated in europiumdoped yttrium oxysulfide by UV laser excitation. A fiber-optic system for light delivery and collection has been designed and tested in laboratory measurements on a rotating disk. Measurements of the effect of oil and magnetic field on sensor performance are reported.