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Сардарлы, Р. М., Ф. Т. Салманов та Н. А. Алиева. "Тип оптических переходов на краю фундаментального поглощения кристаллов TlGaSe-=SUB=-2-=/SUB=- и TInS-=SUB=-2-=/SUB=-, подвергнутых γ-облучению". Журнал технической физики 127, № 9 (2019): 420. http://dx.doi.org/10.21883/os.2019.09.48194.324-18.
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The effect of gamma irradiation on the optical properties of layered TlGaSe2 and TlInS2 crystals in the wavelength range of 400–1,100 nm at 300 K is studied. From the analysis of optical absorption spectra, the energies of direct and indirect optical interband transitions before and after gamma irradiation are determined. It is shown that as the gamma-irradiation dose is accumulated in the range of 0–25 Mrad by TlGaSe2 and TlInS2 single crystals, the energies of direct and indirect allowed optical transitions increase from Egd = 2.06 eV and Egi = 1.90 eV at D = 0 Mrad to Egd = 2.11 eV and Egi = 1.98 eV at D = 25 Mrad for TlGaSe2 and Egd = 2.32 eV crystals and Egi = 2.27 eV at D = 0 Mrad to Egd = 2.35 and Egi = 2.32 eV at D = 25 Mrad for TlInS2 crystals. A decrease in the transmittance at doses from 0 to 5 Mrad and a further increase in the transmittance at the radiation dose D = 25 Mrad are observed.
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Ali, Y., S. Ullah, S. A. Khattak, and M. Ajaz. "Study of pion kaon and proton in proton–carbon interactions at 158 GeV/c using hadron production models." Modern Physics Letters A 34, no. 10 (2019): 1950078. http://dx.doi.org/10.1142/s0217732319500780.
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In this work, we investigate the production of [Formula: see text], [Formula: see text] mesons, protons and antiprotons, by exploiting the theoretical hadron production models: EPOS 1.99, EPOS-LHC and QGSJETII-04, using proton–carbon collisions at a potential laboratory momentum of 158 GeV/c. Laboratory momentum-dependent double differential yields of these particles are studied where it is produced at a polar angle ranging from 0 mrad to 420 mrad for [Formula: see text] mesons while for [Formula: see text] mesons, protons and antiprotons, the angle ranges from 0 mrad to 360 mrad. The QGSJET predicts high yields of the [Formula: see text] mesons for a polar angle ranging from 0 mrad to 20 mrad at the peak of the distribution while beyond 20 mrad, the high yield is demonstrated by EPOS-LHC. In the case of [Formula: see text] mesons and antiprotons, the QGSJETII-04 gives higher yield at the peak of the distribution in all the cases, whereas the EPOS-1.99 and EPOS-LHC produce similar results. In most of the cases at high momentum of the hadrons, the trios are in very good agreement with each other.
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Ajaz, M., Y. Ali, S. Ullah, Q. Ali та U. Tabassam. "Comparison of different hadron production models for the study of π±, K±, protons and antiprotons production in proton–carbon interactions at 90 GeV/c". Modern Physics Letters A 33, № 14 (2018): 1850079. http://dx.doi.org/10.1142/s0217732318500797.
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In this research paper, comprehensive results on the double differential yield of [Formula: see text] and [Formula: see text] mesons, protons and antiprotons as a function of laboratory momentum in several polar angle ranges from 0–420 mrad for pions, 0–360 mrad for kaons, proton and antiproton are reported. EPOS 1.99, EPOS-LHC and QGSJETII-04 models are used to perform simulations. The predictions of these models at 90 GeV/c are plotted for comparison, which shows that QGSJETII-04 model gives overall higher yield for [Formula: see text] mesons in the polar angle interval of 0–40 mrad but for the [Formula: see text] the yield is higher only up to 20 mrad. For [Formula: see text] mesons after 40 mrad, EPOS-LHC predicts higher yield as compared to EPOS 1.99 and QGSJETII-04 while EPOS-LHC and EPOS 1.99 give similar behavior in these two intervals. However, for [Formula: see text] mesons EPOS-LHC and EPOS 1.99 give similar behavior in these two intervals. For of [Formula: see text] mesons, QGSJETII-04 model gives higher predictions in all cases from 0–300 mrad, while EPOS 1.99 and EPOS-LHC show similar distributions. In case of protons, all models give similar distribution but this is not true for antiproton. All models are in good agreement for p [Formula: see text] 20 GeV/c. EPOS 1.99 produce lower yield compared to the other two models from 60–360 mrad polar angle interval.
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Tsukamoto, R., Giuseppe Pezzotti, M. Ogino, et al. "Zirconia Knee Wear and Raman Spectroscopy Studies Compares 3.5-Mrad and 7-Mrad UHMWPE Inserts." Key Engineering Materials 309-311 (May 2006): 1285–88. http://dx.doi.org/10.4028/www.scientific.net/kem.309-311.1285.
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We studied the long-term wear behaviour of alumina-doped zirconia femoral condyles against ultra-high molecular weight polyethylene (UHMWPE) tibial inserts. The simulator kinematics included 20 degrees of flexion/extension, ± 5 degrees of internal/external rotation, and 6 mm of anterior/posterior translation. All knee components were subjected to 10 million cycles of normal walking (2.6 KN max, freq. 1.8 Hz). Lubricant was 50% alpha-calf serum (20 mg/ml protein) with EDTA. The tibial inserts were from one lot of ram-extruded UHMWPE and sterilized with 3.5-Mrad or 7-Mrad radiation dose. Soak controls were stored unloaded in deionised water for 60 days prior to testing. Implants were studied with high-resolution confocal Raman spectroscopy after 10-Mc duration. The wear of control knees (CoCr/3.5-Mrad) averaged 4.5mm3/Mc while the wear with the ZrO2/7-Mrad combination was unmeasurably low even after 10 million cycle duration. Raman Spectroscopy at 10-Mc duration showed only the presence of the desired tetragonal phase. Thus, the ZrO2/7-Mrad bearing combination should prove excellent for active patients who may otherwise risk high wear rates over many years of use.
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Becker, R., та W. B. Herrmannsfeldt. "Why π and mrad?" Review of Scientific Instruments 77, № 3 (2006): 03B907. http://dx.doi.org/10.1063/1.2166430.
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SWELGARD, E. L., F. R. BUSKIRK, J. R. NEIGHBOURS, et al. "EFFECT OF ELECTRON IRRADIATION ON HIGH Tc SUPERCONDUCTORS." Modern Physics Letters B 02, no. 09 (1988): 1055–59. http://dx.doi.org/10.1142/s0217984988000916.
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High T c bulk superconductors, YBa 2 Cu 3 O 6.7 and GdBa 2 Cu 3 O 6.7, were irradiated with 67.5 MeV electrons at dose levels from 0.3 Mrad to 150 Mrad. Resistance versus temperature data show little change in T c after irradiation but significant structural degradation was observed.
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Davis, Edward T., Joseph Pagkalos, and Branko Kopjar. "Polyethylene manufacturing characteristics have a major effect on the risk of revision surgery in cementless and hybrid total hip arthroplasties." Bone & Joint Journal 102-B, no. 1 (2020): 90–101. http://dx.doi.org/10.1302/0301-620x.102b1.bjj-2019-0779.r1.
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Aims The aim of this study was to identify the effect of the manufacturing characteristics of polyethylene acetabular liners on the survival of cementless and hybrid total hip arthroplasty (THA). Methods Prospective cohort study using linked National Joint Registry (NJR) and manufacturer data. The primary endpoint was revision for aseptic loosening. Cox proportional hazard regression was the primary analytical approach. Manufacturing variables included resin type, crosslinking radiation dose, terminal sterilization method, terminal sterilization radiation dose, stabilization treatment, total radiation dose, packaging, and face asymmetry. Total radiation dose was further divided into G1 (no radiation), G2 (> 0 Mrad to < 5 Mrad), G3 (≥ 5 Mrad to < 10 Mrad), and G4 (≥ 10 Mrad). Results A total of 5,329 THAs were revised, 1,290 of which were due to aseptic loosening. Total radiation dose, face asymmetry, and stabilization treatments were found to significantly affect implant survival. G1 had the highest revision risk for any reason and for aseptic loosening and G3 and G4 the lowest. Compared with G1, the adjusted hazard ratio for G2 was 0.74 (95% confidence interval (CI) 0.64 to 0.86), G3 was 0.36 (95% CI 0.30 to 0.43), and G4 was 0.38 (95% CI 0.31 to 0.47). The cumulative incidence of revision for aseptic loosening at 12 years was 0.52 and 0.54 per 100 THAs for G3 and G4, respectively, compared with 1.95 per 100 THAs in G1. Asymmetrical liners had a lower revision risk due to aseptic loosening and reasons other than aseptic loosening compared with symmetric (flat) liners. In G3 and G4, stabilization with vitamin E and heating above melting point performed best. Conclusion Polyethylene liners with a total radiation dose of ≥ 5 Mrad, an asymmetrical liner face, and stabilization with heating above the melting point demonstrate best survival. Cite this article: Bone Joint J 2020;102-B(1):90–101
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LIAO, AN-CHI, WEI-TOU NI, and JOW-TSONG SHY. "PICO-WATT AND FEMTO-WATT WEAK-LIGHT PHASE LOCKING." International Journal of Modern Physics D 11, no. 07 (2002): 1075–85. http://dx.doi.org/10.1142/s021827180200258x.
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Advances in laser physics and its applications have triggered the proposition and development of Laser Astrodynamics. In carrying out research projects on Laser Space Programs, it is necessary to process the laser signal sent back from remote spacecraft. After traveling an extremely long distance, the power of this signal is greatly reduced. Weak-light phase-locking is the key technique used for signal amplification in these space projects. After the returning laser beam is collected by telescope, it is used to phase-lock a local laser oscillator. The local laser then carries the phase information of the remote spacecraft laser. we used diode-pumped non-planar ring cavity Nd:YAG lasers to serve as the remote weak-light laser and the local strong-light laser. We then built an optical phase-locked loop to phase-lock them. The weak-light laser signal was simulated using ND (neutral density)-filters to decrease the light intensity. In the phase detection, we used balanced detection to eliminate laser intensity noise and improve the S/N ratio. Combining this with an appropriate loop filter, we were able to control the laser frequency and improve the phase-locking ability. We phase-locked a 2 nW weak-light beam and a 2 mW strong-light beam with a 57 mrads(rms)phase error. The locking duration was very long. Locking of a 200 pW and a 2007thinsp;μW light beam, with phase error of 200 mrad (rms) and duration of over 2 hours was achieved. The phase error for locking a 200 μW to a 20pW light beam was 160 mrad (rms). The locking duration was also longer than 2 hours. the last locking performed was carried out with a 2 pW and a 200 μW light beam. The phase error and the locking duration were 290 mrad(rms) and 1.5 min respectively.
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Ishikawa, Daisuke, and Alfred Q. R. Baron. "Temperature-gradient analyzers for non-resonant inelastic X-ray scattering." Journal of Synchrotron Radiation 28, no. 3 (2021): 756–68. http://dx.doi.org/10.1107/s160057752100179x.
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The detailed fabrication and performance of the temperature-gradient analyzers that were simulated by Ishikawa & Baron [(2010). J. Synchrotron Rad. 17, 12–24] are described and extended to include both quadratic and 2D gradients. The application of a temperature gradient compensates for geometric contributions to the energy resolution while allowing collection of a large solid angle, ∼50 mrad × 50 mrad, of scattered radiation. In particular, when operating relatively close to backscattering, π/2 − θB = 1.58 mrad, the application of a gradient of 1.32 K per 80 mm improves the measured total resolution from 60 to 25 meV at the full width at half-maximum, while when operating further from backscattering, π/2 − θB = 6.56 mrad, improvement from 330 to 32 meV is observed using a combination of a gradient of 6.2 K per 80 mm and dispersion compensation with a position-sensitive detector. In both cases, the operating energy was 15.8 keV and the incident bandwidth was 22 meV. Notably, the use of a temperature gradient allows a relatively large clearance at the sample, permitting installation of more complicated sample environments.
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El-Shobaky, G. A., A. M. Ghozza та G. M. Mohamed. "Effect of γ-Irradiation on Some Surface and Catalytic Properties of Cr2O3/Al2O3 Solids Precalcined at 700°C". Adsorption Science & Technology 16, № 3 (1998): 163–74. http://dx.doi.org/10.1177/026361749801600302.
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The effects of γ-irradiation (20–160 Mrad) on the surface characteristics (SBET, VP and r) and catalytic properties (in CO oxidation by O2) of chromia/ alumina solids have been investigated. The solids were prepared by mechanical mixing of CrO3 with finely powdered Al(OH)3, followed by drying at 120°C and calcination in air at 700°C. The amounts of chromia in the samples were 8.2 wt% and 27.1 wt%, respectively. The results obtained show that doses of 20–40 Mrad brought about a measurable increase in the surface characteristics (SBET, 46%; VP, 93%; r, 31%) of the sample containing 27.1 wt% Cr2O3 but doses above this limit had the opposite effect. However, the various surface parameters of the sample treated with 160 Mrad were still higher than those of the untreated sample. With the sample containing 8.2 wt% Cr2O3, varying the dosage of γ-irradiation in the range 20–160 Mrad led to smaller variations in the surface parameters. The catalytic activities of both types of sample were decreased by γ-irradiation, with the decrease being more pronounced for samples rich in chromia. Curves relating catalytic activity to dosage exhibited minima at 40 Mrad. The observed decrease in catalytic activity with γ-irradiation was attributed to a decrease in the concentration of catalytically active sites taking part in chemisorption and catalysis of the oxidation of CO by O2 without any change in their energetic nature.
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HUHTANEN, C. N., J. SHIEH, E. WIERBICKI, et al. "Effect of Sugar and Low-Dose Irradiation on Toxin Production by Clostridium botulinum in Comminuted Bacon." Journal of Food Protection 49, no. 2 (1986): 112–16. http://dx.doi.org/10.4315/0362-028x-49.2.112.
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Comminuted bacon, processed to contain target levels of 40 μg NaNO2/g and 0, 0.25 or 0.75% sucrose or 0.75% glucose, was inoculated with a mixture of spores of 20 strains of Clostridium botulinum (400 spores per g) and was canned under vacuum. Portions were irradiated using 137Cs at doses of 0, 0.19, 0.38, 0.75, 1.12 and 1.5 Mrad. Cans were incubated for 1, 2, 4 or 8 wk at 30°C. Some cans of nonirradiated bacon without or with 0.25% sucrose became toxic in 2 wk; with 0.75% sucrose, toxin production was delayed to 8 wk. Bacon irradiated at 0.75 Mrad, made with or without sucrose, became toxic in 2 to 4 wk, whereas most cans of bacon irradiated at 1.5 Mrad remained toxin-free for the 8-wk incubation period. A comparison of bacon made with 0.75% sucrose or glucose showed no difference between the sugars in the rates of toxin production by C. botulinum in irradiated cans of bacon. Irradiation at 0.19 Mrad increased the rate of toxin formation over nonirradiated bacon in sugar-containing (0.75%) bacon, but had no effect in sugar-free bacon. The pH of nonirradiated bacon containing 0.75% glucose or sucrose decreased from pH 6.12 and 6.11, respectively, to pH 5.63 and 5.67 after 8 wk of incubation at 30°C. The titratable acidity showed a concurrent increase. The pH and titratable acidity of bacon irradiated at 0.19 Mrad or higher showed no changes.
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Афанасьев, А. Ю., А. Ю. Бояринцев, И. А. Голутвин та ін. "Изменение характеристик переизлучающих волокон Y-11 и O-2 под действием гамма облучения". Журнал технической физики 128, № 12 (2020): 1973. http://dx.doi.org/10.21883/os.2020.12.50337.104-20.
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The effect of 60Co gamma radiation on the intensity of the reemitted light at the exit from WLS-fibers of Y-11 M and O-2 M type WLS fibers and the subsequent restoration of the characteristics of irradiated fibers after exposure to room temperature are investigated. Irradiation of a low dose rate (0.048 Mrad / h) to a dose of 1 Mrad leads to a slight decrease in the intensity of the reemitted light at the exit of both types of fibers, and with a further increase in the dose, the curve does not change. When irradiated with a dose rate of 0.158 Mrad / h, the characteristics of both types of fibers deteriorate significantly. When the irradiated samples are held at room temperature, fiber characteristics are restored.
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Cammett, Melani. "Jeanne Jeffers Mrad, 1921-2009." Review of Middle East Studies 43, no. 2 (2009): 298–300. http://dx.doi.org/10.1017/s2151348100000938.
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Oláh, László, Hiroyuki K. M. Tanaka, Gergő Hamar, and Dezső Varga. "Investigation of the limits of high-definition muography for observation of Mt Sakurajima." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2137 (2018): 20180135. http://dx.doi.org/10.1098/rsta.2018.0135.
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A multi-wire proportional chamber-based muo- graphy observatory is under development for the monitoring of the internal structure of Mt Sakurajima in Kyushu, Japan. We investigated the limits of large-scale and high-definition muography. We adjusted the parameters of a modified Gaisser model and found that the spectral index of γ = − 2.64 and normalization factor of C = 0.66 reproduce more accurately the measured fluxes than the original parameters at large thickness. A thickness and zenith angle-dependent correction is suggested to the measured muon flux due to the energy cut which is introduced to suppress the background particles. The multiple scattering of muons was simulated across the standard rock and sea-level atmosphere up to the distance of 5 km. We found that multiple scattering decreases from 10 mrad to 4 mrad across the rock due to the decrease in the steepness of muon spectra. The multiple scattering falls down to about 2 mrad after the object in the atmosphere due to the increase in observed arrival zenith angles. The 2 m 2 sized multi-wire proportional chamber-based Muographic Observation System (MMOS) was operating between February and June 2018. Three tracking systems operated reliably with tracking efficiencies of above 95%. The muon flux has been measured correctly down to 10 −3 m −2 sr −1 s −1 . The average density map of Mt Sakurajima has been measured with angular resolution of 12 mrad × 12 mrad (spatial resolution of 34 m × 34 m from the distance of 2.8 km). The average density values were found between 1.4 and 2 g cm −3 , except at the crater regions where lower densities were observed. This article is part of the Theo Murphy meeting issue ‘Cosmic-ray muography’.
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Avalos-Borja, M., E. Adem, L. Cota, and G. Burillo. "Crystallization in highly irradiated poly(vinyl chloride)." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (1990): 820–21. http://dx.doi.org/10.1017/s0424820100177234.
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Poly (vinyl chloride) is one of the most widely used materials in today’s society, and the study of its properties is relevant to many fields. In the present case, we investigate changes that occured in this material when it was exposed to high doses of gamma rays. Previous studies using electron beam irradiation indicated the possibilities of using this material as a “getter” due to its ability to capture gases like CO2 and CO. The present work deales with preliminary results on the structural characteristics of a carbon rich material obtained using ionizing radiation.Radiation treatment was done in several steps, a) irradiation of 1000 Mrad (at dose rate of 0.95 Mrad/hr) in a Gamma Beam Type 651-PT ( Co) source. b) the sample is then extracted with tetrahydrofuran (THF) in order to separate the homopolymer from the gel that was formed during irradiation. c) the gel fraction (crosslinked polymer) was filtered, dried and weighted, and exposed again for 200 Mrad more
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Loane, R. F., E. J. Kirkland, and J. Silcox. "Wavefunction and CBED results of the STEM multislice calculation." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 664–65. http://dx.doi.org/10.1017/s0424820100155293.
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The multislice algorithm has been used to simulate ADF STEM images. Examination of the evolution of the electron wavefunction as it propagates through the specimen, can provide insight into the sources of contrast in the STEM image. Plots of the wavefunction intensity as a function of position and as a convergent beam electron diffraction (CBED) pattern are two complementary views of the diffraction process. Examples from the large number of these plots that are calculated during the ADF STEM calculations will be presented.The simulated specimen consists of multiples of 47 Å (15 slices) of silicon (111). The slices are 65 Å × 66 Å(512 × 512 pixels) in size, setting the maximum included scattering angle to 95 mrad. The incident probe models a 100 keV VG-HB501 STEM at Scherzer focus with either the low resolution pole piece (Cs=3.3 mm, Δf=1100 Å, αap = 8.2 mrad) or the high resolution pole piece (Cs = 0.7 mm, Δf=510 Å, αap=12.1 mrad). The beam and specimen are aligned exactly along the (111) zone axis (no tilt).
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Zaker, Thoalfiqar Ali, Talib Zeedan Taban, and Firas S. Mohammed. "MITIGATING THE INFLUENCE OF DENSE OIL FIRES ON FREE-SPACE OPTICAL COMMUNICATION." EUREKA: Physics and Engineering 3 (May 11, 2020): 69–74. http://dx.doi.org/10.21303/2461-4262.2020.001242.
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This study estimates the performance of a free space optical system (FSO) affected by air pollutants from oil fires. Simulations are performed to evaluate the reliability of optical propagation according to the length of the FSO channels under two beam angle angles. The proposed FSO system parameters such as the Q-factor, BER and reception capacity are successfully used to reduce channel loss. Results demonstrate that the proposed FSO link performs satisfactorily when the divergence angle is 1 mrad and the distance is from 0.5 km to 0.9 km. Q-factor and receiving power decrease when the divergence angle of beam increases to 2 mrad, and a link is achieved when the distance is from 0.5 km to 0.7 km. The eye diagram is used to evaluate and confirm the quality of received data. An eye opening is observed at 0.5 km for both divergence angles. Then, the eye completely closes at 1 km for 2 mrad, thereby degrading the performance. Therefore, these results can be conducted for similar systems optimization options by applying our analysis
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Ishikawa, Daisuke, David S. Ellis, Hiroshi Uchiyama, and Alfred Q. R. Baron. "Inelastic X-ray scattering with 0.75 meV resolution at 25.7 keV using a temperature-gradient analyzer." Journal of Synchrotron Radiation 22, no. 1 (2015): 3–9. http://dx.doi.org/10.1107/s1600577514021006.
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The use of temperature-gradient analyzers for non-resonant high-resolution inelastic X-ray scattering is investigated. The gradient compensates for geometrical broadening of the energy resolution by adjusting the lattice spacing of the analyzer crystal. Applying a ∼12 mK temperature gradient across a 9.5 cm analyzer, resolutions of 0.75 (2) meV FWHM at 25.7 keV for Si(13 13 13) and 1.25 (2) meV at 21.7 keV for Si(11 11 11) were measured, while retaining large (250 mm) clearance between the sample position and detector, and reasonable (9.3 mrad × 8.8 mrad) analyzer acceptance. The temperature control and stability are discussed.
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Nakayama, Kan, Yosimasa Okada, and Hiroyuki Fujimoto. "New beamline optics for the effective use of a wiggler beam." Journal of Synchrotron Radiation 5, no. 3 (1998): 527–29. http://dx.doi.org/10.1107/s0909049597016130.
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A hard X-ray beamline, BL13A, has been constructed for precision diffraction experiments conducted downstream of the multipole wiggler MPW#13 at the Photon Factory. The BL13A line can be used along with the main beamline, BL13B, which accepts the central 4 mrad of the 5 mrad horizontal fan. BL13A uses the remaining horizontal off-axis beam. The beam is diffracted by a double-crystal monochromator which uses asymmetric (422) diffraction with a horizontal diffraction vector. A monochromatic beam with 33.5 keV photon energy is directed to a precision goniometer. Good beam stability and high intensity were obtained.
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Bruccoleri, Christian, and Daniele Mortari. "MRAD: Modified rodrigues vector attitude determination." Journal of the Astronautical Sciences 54, no. 3-4 (2006): 383–90. http://dx.doi.org/10.1007/bf03256496.
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Ding, Man. "Damage Effect of ALD-Al2O3 Based Metal-Oxide-Semiconductor Structures under Gamma-Ray Irradiation." Micromachines 12, no. 6 (2021): 661. http://dx.doi.org/10.3390/mi12060661.
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The radiation response of Al2O3 on silicon substrate under gamma-rays is studied in this article. The atomic layer deposited Al2O3 based metal-oxide-semiconductor structures were irradiated under gamma-ray with the total dose of 1.2 Mrad(Si)/2.5 Mrad(Si)/4 Mrad(Si). The generation, transportation and trapping characteristics of radiation induced charges were studied by using electronic, physical and chemical methods. Firstly, the radiation induced trapped charge density in Al2O3 is up to 1012 cm−2, with the effective trapping efficiency of 7–20% under irradiation. Secondly, the leakage current through Al2O3 changes little with the increase of radiation total dose. Thirdly, oxygen vacancy in Al2O3 and O dangling bonds and Al-Si metallic bonds at Al2O3/Si interface are dominant radiation induced defects in Al2O3/Si system, and the valence band offset between Al2O3 and Si is found to decrease after irradiation. From the results we can see that Al2O3 is radiation resistant from the aspect of leakage current and crystallization characteristics, but the radiation induced charge trapping and new defects in Al2O3/Si structure cannot be ignored. This paper provides a reference for the space application of Al2O3 based MOS devices.
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Morishita, Shigeyuki, Ryo Ishikawa, Yuji Kohno, Hidetaka Sawada, Naoya Shibata, and Yuichi Ikuhara. "Attainment of 40.5 pm spatial resolution using 300 kV scanning transmission electron microscope equipped with fifth-order aberration corrector." Microscopy 67, no. 1 (2017): 46–50. http://dx.doi.org/10.1093/jmicro/dfx122.
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Abstract The achievement of a fine electron probe for high-resolution imaging in scanning transmission electron microscopy requires technological developments, especially in electron optics. For this purpose, we developed a microscope with a fifth-order aberration corrector that operates at 300 kV. The contrast flat region in an experimental Ronchigram, which indicates the aberration-free angle, was expanded to 70 mrad. By using a probe with convergence angle of 40 mrad in the scanning transmission electron microscope at 300 kV, we attained the spatial resolution of 40.5 pm, which is the projected interatomic distance between Ga–Ga atomic columns of GaN observed along [212] direction.
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Kang, L., A. L. Galvin, T. D. Brown, J. Fisher, and Z.-M. Jin. "Wear simulation of ultra-high molecular weight polyethylene hip implants by incorporating the effects of cross-shear and contact pressure." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 222, no. 7 (2008): 1049–64. http://dx.doi.org/10.1243/09544119jeim431.
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The effect of multi-directional cross-shear (CS) motion and contact pressure on ultra-high molecular weight polyethylene (UHMWPE) wear was investigated in this study, based on an integrated experimental and computational approach. The wear factor as a function of CS was determined experimentally from a multi-directional pin-on-plate wear tester under a nominal contact pressure of 1 MPa. A computational wear model was developed which included the effects of CS as well as the load and sliding distance imposed on the hip joint employing a UHMWPE cup against a metallic femoral head under both gait and Leeds ProSim hip joint simulator conditions. The CS ratios were quantified over the articular surface of the UHMWPE cup and the CS-dependent wear factors derived from multi-directional pin-on-plate studies were applied in the computational wear model. Outputs from the computational wear model were validated independently against an experimental hip simulator study. Comparisons of linear and volumetric wear were made between the computational wear model and the hip simulator testing for a nominal conventional (0 MRad) UHMWPE cup of 28 mm diameter and a highly cross-linked (10 MRad) UHMWPE cup. The difference between the computed and experimental volumetric wear was approximately 30 per cent for the 0 MRad UHMWPE, although the worn areas between the prediction and the measurement were similar. For the 10 MRad UHMWPE, the discrepancy was reduced to 16 per cent. In both cases, the computational model predicted a lower wear rate than the experimental simulator testing. The effect of using alternative wear factors under a different nominal contact pressure of 3 MPa was also considered. The input wear factor to the computational model, derived from a constant loaded pin-on-plate test configuration, may underestimate the dynamic effect due to the variation in the load in the hip joint simulator.
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Fagal, Gehan A., Amina A. Attia та Hala G. El-Shobaky. "Catalytic Decomposition of H2O2 over a γ-Irradiated CuO–ZnO/Al2O3 System". Adsorption Science & Technology 16, № 5 (1998): 381–90. http://dx.doi.org/10.1177/026361749801600505.
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A CuO–ZnO/Al2O3, catalyst sample was prepared by wet impregnation methods using Al(OH)3, zinc and copper nitrate solutions followed by drying at 110°C and calcination at 600°C. The nominal molar composition of the resulting material was calculated to be 0.25CuO · 0.03ZnO/Al2O3 Samples of this solid were exposed to varying dosages of γ-irradiation (20–160 Mrad) and the effect of such treatment on their surface characteristics and catalytic activity investigated using nitrogen adsorption studies at −196°C and studies of the decomposition of H2O2 at 30–50°C. The results obtained indicate that doses of γ-rays up to 80 Mrad had no significant effect on the specific surface area. SBET, of the supported mixed oxide material although this quantity increased by 20% when the solid was exposed to γ-irradiation doses of 160 Mrad. In contrast, such treatment brought about a progressive decrease in the catalytic activity of the treated catalyst samples. Thus, the reaction rate constant (k) of the catalyzed reaction measured at 50°C diminished from 8 × 10−2 min−1 to 0.3 × 10−2 min−1 on exposure of the supported mixed oxide material to a dose of 160 Mrad. What was surprising was that the activation energy (δE) of the catalytic reaction decreased as a function of the dose employed whereas it should have been expected to increase in the light of the observed decrease in the catalytic activity. This apparent discrepancy was resolved by recalculating the values of ΔE taking into account any possible changes in the pre-exponential factor of the Arrhenius equation brought about by γ-irradiation. The observed decrease in the catalytic activity due to treatment with γ-rays was attributed, mainly, to the enhanced removal of Brönsted acid centres by the action of such irradiation.
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Kuroki, Shinichiro, Hirofumi Nagatsuma, Milantha de Silva, et al. "Characterization of 4H-SiC nMOSFETs in Harsh Environments, High-Temperature and High Gamma-Ray Radiation." Materials Science Forum 858 (May 2016): 864–67. http://dx.doi.org/10.4028/www.scientific.net/msf.858.864.
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Characteristics of 4H-SiC nMOSFETs with arsenic-doped S/D and NbNi silicide contacts in harsh environments of high-temperature up to 450°C, and high gamma-ray radiation up to over 100 Mrad, were investigated. At high temperature, field effect mobility increased as proportional to T3/2, and threshold voltage was shifted with temperature coefficients of -4.3 mV/K and -2.6 mV/K for oxide thicknesses of 10 nm and 20 nm, respectively. After Co60 gamma-ray exposure of 113 Mrad, the field effect mobility was varied within 8% for oxide thickness of 10 nm, however for 20 nm oxide thickness, this variation was 26%. The threshold voltage shifts were within 6%.
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Thakur, P., M. S. Behra, R. Dogra, A. K. Bhati, and S. C. Bedi. "Static Electric Quadrupole Moments in the Ground State and K = 4–1 Bands in 168Er." Zeitschrift für Naturforschung A 57, no. 6-7 (2002): 591–94. http://dx.doi.org/10.1515/zna-2002-6-754.
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The time differential perturbed angular correlation (TDPAC) technique has been used to study the nuclear quadrupole interactions of the first excited state of ground state rotational band (2+, 80 keV, T1/2 = 1.88 ns) and the band head of the = 41- band (41-,1094 keV, T1/2 = 120 ns) in the 168Er nucleus of a polycrystalline Er host. At room temperature we obtained the electric quadrupole interaction frequencies ω0(K= 0) = 457(15) Mrad/s and ω0(K= 4) = 69(2) Mrad/s, respectively, for the 2+ and 4- isomeric states of 168Er. The ratio of the spectroscopic quadrupole moments, i. e. Qs (K= 4)/Qs (K= 0) = 0.69(3), is independent of any model approximation and the electric field gradient at 168Er in the host metal
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Meng, Dechao, Mu Lan, Zeng-hui Yang, et al. "Gamma-ray irradiation-induced oxidation and disproportionation at the amorphous SiO2/Si interfaces." Journal of Materials Chemistry C 8, no. 47 (2020): 17065–73. http://dx.doi.org/10.1039/d0tc03942j.
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Kume, Tatsuya, Masanori Satoh, Tsuyoshi Suwada, Kazuro Furukawa, and Eiki Okuyama. "Elimination of Gyro Drift by Using Reversal Measurement." International Journal of Automation Technology 9, no. 4 (2015): 381–86. http://dx.doi.org/10.20965/ijat.2015.p0381.
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We aim to realize a large-scale straightness evaluation using a gyro. It detects tangential angles to evaluate a profile without any references. However, fluctuations of angular signal, called gyro drift, are considered a major contributor of error. We adopted a reversal measurement for eliminating the drift. The reversal measurement has been widely used for eliminating stable error from ancient. Here, we periodically performed reversal measurements for eliminating drift of a commercially available fiber optic gyro (FOG) unit. As a result, an angle could be derived with a standard deviation of 0.4 mrad for 1 hour of repeated measurements with an interval of 60 s, even though the gyro has a drift of several mrad/h including the effects of the Earth’s rotation. This indicates that the reversal measurement is effective in reducing the drift.
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Davis, Edward T., Joseph Pagkalos, and Branko Kopjar. "A higher degree of polyethylene irradiation is associated with a reduced risk of revision for aseptic loosening in total hip arthroplasties using cemented acetabular components." Bone & Joint Research 9, no. 9 (2020): 563–71. http://dx.doi.org/10.1302/2046-3758.99.bjr-2020-0135.r1.
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Aims To investigate the effect of polyethylene manufacturing characteristics and irradiation dose on the survival of cemented and reverse hybrid total hip arthroplasties (THAs). Methods In this registry study, data from the National Joint Registry of England, Wales, Northern Ireland and the Isle of Man (NJR) were linked with manufacturing data supplied by manufacturers. The primary endpoint was revision of any component. Cox proportional hazard regression was a primary analytic approach adjusting for competing risk of death, patient characteristics, head composition, and stem fixation. Results A total of 290,770 primary THAs were successfully linked with manufacturing characteristics. Overall 4,708 revisions were analyzed, 1,260 of which were due to aseptic loosening. Total radiation dose was identified as a risk factor and included in the Cox model. For statistical modelling of aseptic loosening, THAs were grouped into three categories: G1 (no radiation); G2 ( > 0 to < 5 Mrad); and G3 ( ≥ 5 Mrad). G1 had the worst survivorship. The Cox regression hazard ratio for revision due to aseptic loosening for G2 was 0.7 (95% confidence interval (CI) 0.58 to 0.83), and for G3 0.4 (95% CI 0.30 to 0.53). Male sex and uncemented stem fixation were associated with higher risk of revision and ceramic heads with lower risk. Conclusion Polyethylene irradiation was associated with reduced risk of revision for aseptic loosening. Radiation doses of ≥ 5 Mrad were associated with a further reduction in risk. Cite this article: Bone Joint Res 2020;9(9):563–571.
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Bentley, J., K. C. Walter, and N. D. Evans. "Bonding in Ion-Implanted Diamond-Like Carbon Films Characterized by TEM Spectrum Lines and Energy-Filtered Imaging." Microscopy and Microanalysis 6, S2 (2000): 154–55. http://dx.doi.org/10.1017/s1431927600033262.
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Many of the electrical, mechanical, and electrochemical properties of diamond-like carbon (DLC) coatings are determined by the amount of sp3 bonding. Correlations of bonding and properties are important in efforts to optimize coatings for specific applications. DLC thin films were grown at LANL by plasma deposition and subsequently ion implanted with N or Ar. Cross-sectioned TEM specimens were characterized with a Gatan imaging filter (GIF) interfaced to a LaB6 Philips CM30T at the ORNL SHaRE User Facility. For elemental distribution maps the following conditions were used: incident beam divergence α = 2.9 mrad, collection angle β = 4.8 mrad, slit width ΔE = 30 eV, exposure times of typically 5 s, 2x-binned 512×512 images, and TEM magnification ∼2000. The standard 3-window method was used for producing elemental maps with AE-r background extrapolation; 2-window jump-ratio images were also produced.
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Presa, P. de la, K. P. Lieb, M. Uhrmacher, and L. Ziegeler. "Perturbed Angular Correlation Studies in SrTiO3 Single Crystals." Zeitschrift für Naturforschung A 55, no. 1-2 (2000): 237–41. http://dx.doi.org/10.1515/zna-2000-1-242.
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The quadrupole hyperfine interactions of 111Cd/111 In probe nuclei in single-crystalline SrTiO3 perovskite samples were investigated using Perturbed Angular Correlation spectroscopy. Three electric field gradients were detected and their fractions and hyperfine parameters were measured in the temperature range from 26 to 700 K. The fraction f0 having a vanishing quadrupole frequency, as expected for 111Cd on substitutional sites in a cubic lattice, starts to develop around 300 K and reaches 100% at 700 K. Two well-defined EFG's having closely lying quadrupole frequencies and asymmetry parameters of ωQi = 49.1(3) Mrad/s, 77, η0= 0.10(2) and ωQ2 = 51.8(3) Mrad/s, η2 = 0.12(2), at room temperature, were identified in the temperature range from 250 to 530 K, and their (100) orientation in the lattice was determined. They are associated with electronic defects at the probe atoms.
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Maletis, Gregory B., Jason Chen, Maria C. S. Inacio, Rebecca M. Love, and Tadashi T. Funahashi. "Increased Risk of Revision After Anterior Cruciate Ligament Reconstruction With Bone–Patellar Tendon–Bone Allografts Compared With Autografts." American Journal of Sports Medicine 45, no. 6 (2017): 1333–40. http://dx.doi.org/10.1177/0363546517690386.
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Background: The use of allograft tissue for anterior cruciate ligament reconstruction (ACLR) remains controversial. Purpose: To compare the risk of aseptic revision between bone–patellar tendon–bone (BPTB) autografts and BPTB allografts. Study Design: Cohort study; Level of evidence, 2. Methods: A retrospective cohort study of prospectively collected data was conducted using the Kaiser Permanente ACLR Registry. A cohort of patients who underwent primary unilateral ACLR with BPTB autografts and BPTB allografts was identified. Aseptic revision was the endpoint. The type of graft and allograft processing method (nonprocessed, <1.8-Mrad, and ≥1.8-Mrad irradiation) were the exposures of interest evaluated. Age (≤21 and ≥22 years) was evaluated as an effect modifier. Analyses were adjusted for age, sex, and race. Kaplan-Meier curves and Cox proportional hazards models were employed. Hazard ratios (HRs) and 95% CIs are provided. Results: The BPTB cohort consisted of 5586 patients: 3783 (67.7%) were male, 2359 (42.2%) were white, 1029 (18.4%) had allografts (nonprocessed: 155; <1.8 Mrad: 525; ≥1.8 Mrad: 288), and 4557 (81.6%) had autografts. The median age was 34.9 years (interquartile range [IQR], 25.4-44.0) for allograft cases and 22.0 years (IQR, 17.6-30.0) for autograft cases. The estimated cumulative revision rate at 2 years was 4.1% (95% CI, 2.9%-5.9%) for allografts and 1.7% (95% CI, 1.3%-2.2%) for autografts. BPTB allografts had a significantly higher adjusted risk of revision than BPTB autografts (HR, 4.54; 95% CI, 3.03-6.79; P < .001). This higher risk of revision was consistent with all allograft processing methods when compared with autografts and was also consistently higher in patients with allografts regardless of age. Conclusion: When BPTB allograft tissue was used for ACLR, an overall 4.54 times adjusted higher risk of revision was observed compared with surgery performed with a BPTB autograft. Whether the tissue was irradiated with either high- or low-dose radiation, chemically processed, or not processed at all made little difference in the risk of revision. The differences in the revision risk were also consistent in younger and older patients. Surgeons and patients should be aware of the increased risk of revision when a BPTB allograft is used for ACLR.
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Egerton, R. F., S. C. Cheng, and T. Malis. "Parameterization of the mean free path for inelastic scattering of fast electrons." Proceedings, annual meeting, Electron Microscopy Society of America 45 (August 1987): 122–23. http://dx.doi.org/10.1017/s0424820100125543.
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The areas, Iz and It, under the zero-loss peak and under the entire energy-loss spectrum (of a sample of thickness t) are related by the formula:t/ƛ(β) = ln (It/Iz) (1)where ƛ(β) is the inelastic mean free path for all energy losses and for scattering into the collection aperture, of semiangle β. We have used Eq.(l) to experimentally determine ƛ(β) by electron energy-loss spectroscopy of specimens of known composition and thickness. In the case of crystalline samples, the local thickness t was measured by convergent-beam diffraction. In the case of evaporated thin-film specimens, the average thickness was obtained by accurately weighing the substrate before and after deposition. The energy-loss spectroscopy was carried out in CTEM mode with incident energies Eo between 20keV and 120keV, and with collection semiangles in the range 0.2 mrad to 100 mrad.
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Li, Qing, Shaoxiong Xu, Yangjie Xu, et al. "Method to Measure Light Spot Position in Beacon-Less Inter-Satellite Communication System." Applied Sciences 9, no. 15 (2019): 3032. http://dx.doi.org/10.3390/app9153032.
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This article focuses on a beacon-less Inter-satellite optical wireless communication (Is-OWC) system. This system uses the same wavelength for the transmitted and received laser beams and uses part of communication light beam as beacon light instead of an additional high divergent beacon laser. Thus, a part of transmitted light will be reflected in optical path and leaked into acquisition, tracking and targeting (ATP) subsystem. This reflected light will seriously interfere with the spot position measurement of received light. To solve this problem, we propose a new method based on intensity modulation and cyclic cross-correlation (CCR). Experiment results show that even when the reflected and received beams differ in intensity by 91.7 times, we can still accurately detect the received light spot position by using the proposed method, where the maximum error is 0.026 mrad and the root mean square error is as low as 0.012 mrad.
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Matsuyama, S., K. Ishii, S. Suzuki, et al. "Development of a high-current microbeam system." International Journal of PIXE 24, no. 03n04 (2014): 101–10. http://dx.doi.org/10.1142/s0129083514400038.
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We report on the development of a high-current microbeam system for wavelength-dispersive X-ray micro particle-induced X-ray emission (WDX-[Formula: see text]-PIXE) for chemical state mapping. The microbeam system is composed of two slits and a quadrupole doublet lens mounted on a heavy rigid support. The microbeam system is installed immediately after a switching magnet. A beam brightness of [Formula: see text] is obtained at a half-divergence of 0.1 mrad. A beam current of more than 300 pA is obtained for object sizes of [Formula: see text] with a half-divergence of 0.2 mrad, which corresponds to a beam spot size of [Formula: see text]. The calculated spot size of the beam was [Formula: see text] and the measured spot size was [Formula: see text]. The WDX-[Formula: see text]-PIXE system with the microbeam system is now operational.
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El-Shobaky, G. A., S. A. El-Molla та S. A. Ismail. "Effects of γ-Irradiation on the Surface and Catalytic Properties of Co3O4/MgO Systems Aged for One Year". Adsorption Science & Technology 20, № 10 (2002): 1037–49. http://dx.doi.org/10.1260/026361702321705302.
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The effects of γ-rays (20–160 Mrad) on the surface and catalytic properties of two Co3O4/MgO systems were investigated. The formulae of the investigated solids were 0.05Co3O4/MgO and 0.2Co3O4/MgO, respectively, both prepared by the impregnation method and calcined at 500°C. The irradiated samples were left for one year in sealed tubes before any measurements were undertaken. γ-Irradiation of the investigated solids resulted in a progressive decrease in the particle size of the Co3O4 and MgO phases. This treatment also led to a measurable increase in the specific surface area of the treated solids to an extent proportional to the γ-ray dosage. Treatment of the Co3O4/MgO system with different doses of γ-rays brought about a significant increase in the catalytic activity expressed both as the reaction rate constant and as the reaction rate constant per unit surface area. However, the curve relating to the catalytic activity and dosage of γ-rays showed maxima located at 40 and 80 Mrad for samples having the formula 0.05Co3O4/MgO and 0.2Co3O4/MgO, respectively. Furthermore, samples exposed to 160 Mrad showed a larger catalytic activity than the unirradiated samples. The results demonstrate the role of γ-rays in inhibiting the deterioration of the catalytic activity of the investigated systems as a function of aging time. The irradiation process did not modify the activation energy of the catalyzed reaction but altered the concentration of active centres on the surfaces of the solids without changing their energetic nature.
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El-Shobaky, G. A., A. S. Ahmad, A. M. Ghozza та S. M. El-Khouly. "Surface and Catalytic Properties of γ-Irradiated Fe2O3/Al2O3 Solids". Adsorption Science & Technology 13, № 3 (1996): 153–63. http://dx.doi.org/10.1177/026361749601300302.
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Two specimens of Fe2O3/Al2O3 solids were prepared by impregnating a known mass of finely-powdered Al(OH)3 with calculated amounts of ferric nitrate solutions followed by drying at 120°C and calcination in air at 400°C for 4 h. The mixed solids thus prepared had the nominal molar compositions 0.06Fe2O3/Al2O3 and 0.125Fe2O3/Al2O3 (FeAl-I and FeAl-II). The surface and catalytic properties of various irradiated solids (15–200 Mrad) were studied using nitrogen adsorption at −196°C and catalysis of CO oxidation by O2 at 150–280°C using a static method. The results obtained revealed that γ-irradiation at doses between 15 and 80 Mrad resulted in a progressive decrease (7–22%) in the surface area of the treated solids. Treatment with doses above this limit exerted an opposite effect. γ-Irradiation also resulted in a widening of the pores of the irradiated adsorbents. The catalytic activity of the FeAl-I solid was influenced slightly by γ-rays while the FeAl-II catalyst was significantly modified by this treatment. The reaction rate constant per unit surface area of the catalytic reaction conducted at 280°C over the FeAl-II solid decreased (65%) by exposure to doses up to 120 Mrad, then increased on increasing the dose above this limit. This did not modify the mechanism of the catalytic reaction, but changed the number of catalytically-active sites taking part in chemisorption and catalysis of the CO oxidation reaction without affecting their energetic nature.
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Mrad, Bchira Ben. "BCHIRA BEN MRAD: A PIONEER FEMINIST (1913-1993)." International Journal of Research -GRANTHAALAYAH 8, no. 8 (2020): 302–18. http://dx.doi.org/10.29121/granthaalayah.v8.i8.2020.1058.
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Can one understand the present without knowing the past? Isn’t life a continuation of the past and doesn’t the present owe many of its characteristics to the past? Asking these questions helps one to figure out how women who lived in a secluded and closed environment were able to break the walls that separated them from the public sphere. It is thus that we come to realize and understand how Bchira Ben Mrad’s (from now on: BBM) initiative in the early 1930s did not start from nowhere but had its origins in the women’s past of her country.
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Haque, Md Monirul, H. Yamada, A. Moon, and M. Yamada. "Far-IR/THz Spectroscopy Beamline MIRRORCLE-6FIR at SLLS of Ritsumeikan University." Journal of Scientific Research 1, no. 1 (2008): 31–37. http://dx.doi.org/10.3329/jsr.v1i1.1133.
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A new beamline, MIRRORCLE-6FIR for far infrared-terahertz (THZ) spectroscopy (FIRS) has been recently constructed at the synchrotron light life science center (SLLS) of Ritsumeikan University. An exactly circular optics with vertical angle has been employed as the first mirror which collects synchrotron radiation (SR) photons emitted into 2π of a circular electron orbit of length 1 m only. An exit opening on its surface can extract SR photons up to 264 mrad in horizontal and 198 mrad in vertical. The optimum optical system has been determined by using ray trace simulation code ZEMAX. The purpose is to develop an FIRS beamline with high power FIR. The design of the beamline optics with the results of its ray-tracing are reported in this article.Keywords: MIRRORCLE; Synchrotron radiation; Beam line; Ray-tracing; Terahertz; Far infrared spectroscopy. © 2009 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v1i1.1133
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Schaeffer, Maurice S., and John L. Campbell. "Vertical Disparity in Advanced Automotive Displays." Proceedings of the Human Factors Society Annual Meeting 32, no. 19 (1988): 1443–47. http://dx.doi.org/10.1177/154193128803201929.
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The optical systems being considered for automotive virtual image displays may confront drivers with significantly more vertical disparity than their military counterparts. Military head-up displays, for example, are limited to 1 milliradian (mrad) of vertical disparity whereas automotive displays may have 5 mrad. Three experiments were performed to examine performance with virtual image displays as a function of amount of vertical disparity. Stimuli were simple speedometer dials with embedded tripmeters representing both analog and digital display tasks. Stimuli were presented tachistoscopically and subjects were required to read one or both instruments on each trial. Disparity did not affect performance accuracy. Large disparities did, however, result in diplopia and, possibly, suppression of one of the visual images. Nevertheless, it appears that, at least in the driving situation, where displays are used intermittently and briefly for the information contained in them, comparatively large amounts of vertical disparity in displays will not degrade performance and may not even be noticed.
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SIDDIQI, SAADAT A., RABIA SIDDIQUI та SALAMAT ALI. "EFFECT OF GAMMA IRRADIATION ON YBa2Cu3O7-δ HIGH TEMPERATURE SUPERCONDUCTORS". Modern Physics Letters B 22, № 27 (2008): 2699–707. http://dx.doi.org/10.1142/s0217984908017217.
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Samples of YBa 2 Cu 3 O 7-δ superconducting ceramic were prepared and characterized by resistivity measurements using the four probe method and structural analysis using X-ray diffraction (XRD). XRD-patterns show the presence of orthorhombic Y -123 phase with a small fraction of secondary phase, YBa 2 Cu 3 O 5. Samples were irradiated with gamma (γ) rays using Co 60 source with five successive doses of 2.5 Mrad. A monotonic increase in the Tc0 value was observed for radiation dosage up to 10 Mrad. When exposed to even higher γ-doses, the Tc0 value leveled off at a saturation value or decreased. XRD-analysis shows slightly changed values of the lattice constants and a mild shift of diffraction peaks towards a lower 2θ value. These observations indicate structural changes in YBa 2 Cu 3 O 7-δ induced upon gamma irradiation. The present work describes our experimental findings and attempts to offer a theoretical explanation for the effects observed.
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Poo, A. N., C. L. Teo, M. K. Loh, and S. L. Tay. "Design and Development of a Two-Axis Passive Line-of-Sight Stabilization System." Journal of Mechanical Design 117, no. 1 (1995): 173–79. http://dx.doi.org/10.1115/1.2826103.
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The line-of-sight (LOS) stabilization system is basically a system that has the capability of maintaining the sightline—for example, of an optical sensor—fixed in inertial space even when the system is subjected to an external vibrational environment. This paper examines and presents the feasibility of using a passive LOS stabilization system to maintain the sightline stability to within 1 mrad when it is subjected to linear and angular vibrations and other disturbances. Equations of motion of the system as well as the vibrational response equations are presented. From these equations, design parameters that affect the vibrational response of the system are established. A prototype of the LOS stabilization system has been built. The pointing stability of this prototype with different values of the design parameters is evaluated and compared with simulation results. Initial test results on the prototype are encouraging, with pointing stability of less than 1 mrad on both axes, which is within the original design objective.
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Zheng, Anrui, Yang Huang, and Shiming Gao. "Modeling and Spatial Diversity-Based Receiving Improvement of In-Flight UAV FSO Communication Links." Applied Sciences 11, no. 14 (2021): 6365. http://dx.doi.org/10.3390/app11146365.
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An in-flight unmanned aerial vehicle (UAV) free-space optical (FSO) communication channel model is proposed by considering the beam deviation of the UAV under different motion states and the phase distortion caused by atmospheric turbulences. The influence of the different motion states and turbulences on the communication quality is evaluated through phase screen and Monte Carlo methods. When the average bit error rate (BER) is 10−5, the signal-to-noise ratio (SNR) should be increased from 13 dB to 20 dB when the tilt angle of the UAV increases from 0 to 5 mrad. An SNR of up to 20 dB is required when the variance of the wind σα2 is 2 mrad. The performance of the in-flight UAV FSO link can be effectively improved through spatial diversity receiving technology. The BER of lower than 10−5 can be obtained just with an SNR of 13 dB if the spatial diversity array with four receivers is used.
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Martin, Frederick W. "A Proposal for Improved Helium Microscopy." Microscopy and Microanalysis 20, no. 5 (2014): 1619–22. http://dx.doi.org/10.1017/s1431927614000555.
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AbstractElimination of the electrostatic objective lens and alternative use of a Cc- and Cs-corrected quadrupole doublet may increase the useful working distance of the helium microscope, improve its resolution from 3 to 0.3 Å, and improve its optimum convergence angle from 0.4 to 4 mrad.
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El-Shobaky, G. A., A. M. Ghozza та G. M. Mohamed. "Surface and Catalytic Properties of γ-Irradiated Cr2O3/Al2O3 Solids". Adsorption Science & Technology 15, № 6 (1997): 465–76. http://dx.doi.org/10.1177/026361749701500607.
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Two samples of Cr2O3/Al2O3 were prepared by mixing a known mass of finely powdered Al(OH)3 with a calculated amount of CrO3 solid followed by drying at 120°C and calcination at 400°C. The amounts of chromium oxide employed were 5.66 and 20 mol% Cr2O3, respectively. The calcined solid specimens were then treated with different doses of γ-rays (20–160 Mrad). The surface and catalytic properties of the different irradiated solids were investigated using nitrogen adsorption at −196°C and the catalysis of CO oxidation by O2 at 300–400°C. The results revealed that γ-rays brought about a slight decrease in the BET surface area, SBET (15%), and in the total pore volume, Vp (20%), of the adsorbent containing 5.66 mol% Cr2O3. The same treatment increased the total pore volume, Vp (36%), and the mean pore radius, r̄ (43%), of the other adsorbent sample without changing its BET surface area. The catalytic activities of both catalyst samples were found to increase as a function of dose, reaching a maximum value at 80–160 Mrad and 40 Mrad for the solids containing 5.66 and 20 mol% Cr2O3, respectively. The maximum increase in the catalytic activity measured at 300°C was 59% and 100% for the first and second catalyst samples, respectively. The induced effect of γ-irradiation on the catalytic activity was an increase in the concentration of catalytically active sites taking part in chemisorption and in the catalysis of CO oxidation by O2 without changing their energetic nature. This was achieved by a progressive removal of surface hydroxy groups during the irradiation process.
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Pennycook, S. J., G. Duscher, R. Buczko, and S. T. Pantelides. "The Si/SiO2 Interface: Atomic Structures, Composition, Strain And Energetics." Microscopy and Microanalysis 5, S2 (1999): 122–23. http://dx.doi.org/10.1017/s1431927600013933.
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A number of recent studies of grain boundaries and heterophase interfaces have demonstrated the power of combining Z-contrast STEM imaging, EELS and first-principles theoretical modeling to give an essentially complete atomic scale description of structure, bonding and energetics. Impurity sites and valence can be determined experimentally and configurations determined through calculations.Here we present an investigation of the Si/SiO2 interface. The Z-contrast image in Fig. la, taken with the VG Microscopes HB603U STEM, shows that the atomic structure of Si is maintained up to the last layers visible. The decrease in intensity near the interface could originate from interfacial roughness of around one unit cell (∼0.5 nm), or may represent dechanneling in the slightly buckled columns induced by the oxide. Fig. lb, taken from a sample with ∼1 nm interface roughness, shows a band of bright contrast near the interface. This is not due to impurities or thickness variation since it disappears on increasing the detector angle from 25 mrad to 45 mrad (Fig. lc), and is therefore due to induced strain.
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Drakopoulos, Michael, Thomas Connolley, Christina Reinhard, et al. "I12: the Joint Engineering, Environment and Processing (JEEP) beamline at Diamond Light Source." Journal of Synchrotron Radiation 22, no. 3 (2015): 828–38. http://dx.doi.org/10.1107/s1600577515003513.
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I12 is the Joint Engineering, Environmental and Processing (JEEP) beamline, constructed during Phase II of the Diamond Light Source. I12 is located on a short (5 m) straight section of the Diamond storage ring and uses a 4.2 T superconducting wiggler to provide polychromatic and monochromatic X-rays in the energy range 50–150 keV. The beam energy enables good penetration through large or dense samples, combined with a large beam size (1 mrad horizontally × 0.3 mrad vertically). The beam characteristics permit the study of materials and processes inside environmental chambers without unacceptable attenuation of the beam and without the need to use sample sizes which are atypically small for the process under study. X-ray techniques available to users are radiography, tomography, energy-dispersive diffraction, monochromatic and white-beam two-dimensional diffraction/scattering and small-angle X-ray scattering. Since commencing operations in November 2009, I12 has established a broad user community in materials science and processing, chemical processing, biomedical engineering, civil engineering, environmental science, palaeontology and physics.
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Pennycook, S. J., G. Duscher, R. Buczko, and S. T. Pantelides. "The Si/SiO2 Interface: Atomic Structures, Composition, Strain and Energetics." Microscopy and Microanalysis 7, S2 (2001): 768–69. http://dx.doi.org/10.1017/s1431927600029913.
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A number of recent studies of grain boundaries and heterophase interfaces have demonstrated the power of combining Z-contrast STEM imaging, EELS and first-principles theoretical modeling to give an essentially complete atomic scale description of structure, bonding and energetics. Impurity sites and valence can be determined experimentally and configurations determined through calculations.Here we present an investigation of the Si/SiO2 interface. The Z-contrast image in Fig. la, taken with the VG Microscopes HB603U STEM, shows that the atomic structure of Si is maintained up to the last layers visible. The decrease in intensity near the interface could originate from interfacial roughness of around one unit cell (∼0.5 nm), or may represent dechanneling in the slightly buckled columns induced by the oxide. Fig. lb, taken from a sample with ∼1 nm interface roughness, shows a band of bright contrast near the interface. This is not due to impurities or thickness variation since it disappears on increasing the detector angle from 25 mrad to 45 mrad (Fig. lc), and is therefore due to induced strain.
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Nagaraj, Shashank, Vikram Singh, Halepoojar Siddalingappa Jayanna, Kagalagodu Manjunathiah Balakrishna, and Ramakrishna Damle. "60Co-Gamma Ray Induced Total Dose Effects on P-Channel MOSFETs." Indian Journal of Materials Science 2013 (November 3, 2013): 1–5. http://dx.doi.org/10.1155/2013/465905.
Full textAbstract:
Total Dose Effect (TDE) on solid state devices is of serious concern as it changes the electrical properties leading to degradation of the devices and failure of the systems associated with them. Ionization caused due to TDE in commercial P-channel Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) has been studied, where the failure mechanism is found to be mainly a result of the changes in the oxide properties and the surface effects at the channel beneath the gate oxide. The threshold voltage of the MOSFETs was found to shift from −0.69 V to −2.41 V for a total gamma dose of 1 Mrad. The net negative threshold shifts in the irradiated devices reveal the major contribution of oxide trapped charges to device degradation. The radiation induced oxide and interface charge densities were estimated through subthreshold measurements, and the trap densities were found to increase by one order in magnitude after a total gamma dose of 1 Mrad. Other parameters like transconductance, subthreshold swing, and drain saturation current are also investigated as a function of gamma dose.
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Rajesh, C., K. C. Manoj, G. Unnikrishnan, and E. Purushothaman. "Investigation on Ageing Characteristics of Short Nylon-6 Fibre Reinforced NBR Composites." Progress in Rubber, Plastics and Recycling Technology 24, no. 4 (2008): 239–53. http://dx.doi.org/10.1177/147776060802400402.
Full textAbstract:
The ageing characteristics of nylon 6 fibre reinforced NBR composites have been analysed by exposing them to degrading agents such as heat and gamma (γ) radiation. The effects of fibre loading, curing systems and bonding agents on the retention of tensile properties of the composite samples which were exposed to these degrading agents have been studied. The addition of fibres improves the ageing resistance of NBR. The DCP cured composites exhibit a reduction in their ability to retain the elastic modulus as the thermal ageing period increases from 7 to 14 days, whereas sulfur cured composites show a reverse trend. The efficiency for the retention of modulus of sulfur cured samples increases as the dosage of γ-radiation increases from 5 to 10 Mrad whereas a higher dose of 15 Mrad lowers it. However, the DCP cured samples show a continuous reduction in their ability to retain modulus. The composite system containing hexa-resorcinol as the bonding agent has better resistance to heat and γ-radiation than the unbonded one.