25 results on '"D. Y. Lo"'
Search Results
2. Martian Thermospheric Response to an X8.2 Solar Flare on 10 September 2017 as Seen by MAVEN/IUVS
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S. K. Jain, J. Deighan, N. M. Schneider, A. I. F. Stewart, J. S. Evans, E. M. B. Thiemann, M. S. Chaffin, M. Crismani, M. H. Stevens, M. K. Elrod, A. Stiepen, W. E. McClintock, D. Y. Lo, J. T. Clarke, F. G. Eparvier, F. Lefévre, F. Montmessin, G. M. Holsclaw, P. C. Chamberlin, and B. M. Jakosky
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- 2018
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3. Global Aurora on Mars During the September 2017 Space Weather Event
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N. M. Schneider, S. K. Jain, J. Deighan, C. R. Nasr, D. A. Brain, D. Larson, R. Lillis, Ali Rahmati, J. S. Halekas, C. O. Lee, M. S. Chaffin, A. Stiepen, M. Crismani, J. S. Evans, M. H. Stevens, D. Y. Lo, W. E. McClintock, A. I. F. Stewart, R. V. Yelle, J. T. Clarke, G. M. Holsclaw, F. Lefevre, F. Montmessin, and B. M. Jakosky
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- 2018
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4. Dayside Temperature Maps of the Upper Mesosphere and Lower Thermosphere of Mars Retrieved From MAVEN IUVS Observations of O I 297.2 nm Emission
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J. S. Evans, E. Soto, S. K. Jain, J. Deighan, M. H. Stevens, M. S. Chaffin, D. Y. Lo, S. Gupta, N. M. Schneider, and S. Curry
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Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) - Published
- 2023
5. Nitric oxide nightglow and Martian mesospheric circulation from MAVEN/IUVS observations and LMD‐MGCM predictions
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A. Stiepen, S. K. Jain, N. M. Schneider, J. I. Deighan, F. González‐Galindo, J.‐C. Gérard, Z. Milby, M. H. Stevens, S. Bougher, J. S. Evans, A. I. F. Stewart, M. S. Chaffin, M. Crismani, W. E. McClintock, J. T. Clarke, G. M. Holsclaw, F. Montmessin, F. Lefèvre, F. Forget, D. Y. Lo, B. Hubert, and B. M. Jakosky
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- 2017
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6. Martian mesospheric cloud observations by IUVS on MAVEN: Thermal tides coupled to the upper atmosphere
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M. H. Stevens, D. E. Siskind, J. S. Evans, S. K. Jain, N. M. Schneider, J. Deighan, A. I. F. Stewart, M. Crismani, A. Stiepen, M. S. Chaffin, W. E. McClintock, G. M. Holsclaw, F. Lefèvre, D. Y. Lo, J. T. Clarke, F. Montmessin, and B. M. Jakosky
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- 2017
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7. Neutral density response to solar flares at Mars
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E. M. B. Thiemann, F. G. Eparvier, L. A. Andersson, C. M. Fowler, W. K. Peterson, P. R. Mahaffy, S. L. England, D. E. Larson, D. Y. Lo, N. M. Schneider, J. I. Deighan, W. E. McClintock, and B. M. Jakosky
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- 2015
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8. New observations of molecular nitrogen in the Martian upper atmosphere by IUVS on MAVEN
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M. H. Stevens, J. S. Evans, N. M. Schneider, A. I. F. Stewart, J. Deighan, S. K. Jain, M. Crismani, A. Stiepen, M. S. Chaffin, W. E. McClintock, G. M. Holsclaw, F. Lefèvre, D. Y. Lo, J. T. Clarke, F. Montmessin, S. W. Bougher, and B. M. Jakosky
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- 2015
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9. The structure and variability of Mars upper atmosphere as seen in MAVEN/IUVS dayglow observations
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S. K. Jain, A. I. F. Stewart, N. M. Schneider, J. Deighan, A. Stiepen, J. S. Evans, M. H. Stevens, M. S. Chaffin, M. Crismani, W. E. McClintock, J. T. Clarke, G. M. Holsclaw, D. Y. Lo, F. Lefèvre, F. Montmessin, E. M. B. Thiemann, F. Eparvier, and B. M. Jakosky
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- 2015
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10. Immunogenicity evaluation of Gam-COVID-Vac (Sputnik V)
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I. A. Kirillov, A. P. Pirozhkov, V. V. Rubtsov, S. Ya. Loginova, N. A. Saifulina, T. M. Plekhanova, M. A. Timofeev, D. A. Kutaev, D. Y. Logunov, A. L. Gintsburg, and S. V. Borisevich
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humoral immunity ,virus neutralising antibodies ,vaccine ,sputnik v ,gam-covid-vac ,covid-19, sars-cov-2 ,elisa ,immunoglobulin g ,Biotechnology ,TP248.13-248.65 ,Medicine - Abstract
In November 2020, the Armed Forces of the Russian Federation began mass immunisation of the personnel with Gam-COVID-Vac (Sputnik V), the first Russia vaccine against the new coronavirus infection (COVID-19). Thus, it became necessary to assess post-vaccination antibody levels and the duration and intensity of humoral immunity to COVID-19.The aim of the study was to investigate the immunogenicity and efficacy of Gam-COVID-Vac in military medical staff after vaccination.Materials and methods: the authors determined the presence of specific antibodies in the serum of individuals immunised with Gam-COVID-Vac (477 volunteers) and COVID-19 convalescents (73 patients), using virus neutralisation (VN), enzyme-linked immunosorbent assay (ELISA) with reagent kits by several manufacturers, and immunoblotting. The results of the study were evaluated using analysis of variance.Results: VN detected virus neutralising antibodies in 90.7% of vaccinated subjects; ELISA, in 95.4%. Both VN and ELISA showed lower antibody levels in the vaccinated over 50 years of age. ELISA demonstrated a significantly higher concentration of anti-SARS-CoV-2 spike IgG in the Gam-COVID-Vac group than in the COVID-19 convalescent group. The correlation between antibody detection results by VN and ELISA was the strongest when the authors used their experimental reagent kit for quantitative detection of virus neutralising antibodies by competitive ELISA with the recombinant human ACE2 receptor. Having analysed the time course of neutralising antibody titres, the authors noted a significant, more than two-fold decrease in geometric means of the titres three months after administration of the second vaccine component.Conclusions: the subjects vaccinated with Gam-COVID-Vac gain effective humoral immunity to COVID-19. The decrease in titres indicates the need for revaccination in 6 months.
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- 2022
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11. Positive influence of<scp>l</scp>-carnitine on the different muscle fibres types of racing pigeons
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Kun-Wei Chan, F. H. Tsai, Ming-Huang Chang, D. Y. Lo, Shih-Jen Chou, Jyh-Mirn Lai, Jiann-Hsiung Wang, and Zhi-Jia Zheng
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Aging ,medicine.medical_specialty ,Flexor Carpi Ulnaris ,ATPase ,Muscle Fibers, Skeletal ,Muscle Proteins ,Biology ,chemistry.chemical_compound ,Food Animals ,Oral administration ,In vivo ,Carnitine ,Internal medicine ,Lactate dehydrogenase ,medicine ,Animals ,RNA, Messenger ,Columbidae ,Succinate dehydrogenase ,Reverse transcription polymerase chain reaction ,Endocrinology ,Gene Expression Regulation ,Biochemistry ,chemistry ,biology.protein ,Animal Science and Zoology ,medicine.drug - Abstract
Succinate dehydrogenase (SDH), Ca(2+) ATPase, Lactate dehydrogenase (LDH), are involved in energy metabolism. These enzymes can be used as indicators of the energy capacity of aerobic cells. The study investigated the effects of L-carnitine supplementation on M. pectoralis superficialis, M. pectoralis profundus, M. extensor carpi radialis muscle and M. flexor carpi ulnaris. Twenty-eight racing pigeons hatched at the same time were divided randomly into three groups. Eight pigeons, which were used as the control group, were sacrificed at 92-day old. The remaining twenty pigeons continued training until they reached 157-day old, with half the pigeons getting 25 mg/head/day of L-carnitine, while the other half given the same amount of water. The pigeons were assessed by histochemical methods and reverse transcription polymerase chain reaction (RT-PCR). To assess influence of L-carnitine on muscle fibre composition and the performance of three genes' mRNA, this study applied SDH localization, SDH, Ca(2+) ATPase and LDH mRNA expression to examine the results after oral administration of L-carnitine in vivo in racing pigeons. The results showed that L-carnitine significantly elevated the amount of white muscle fibre type IIa (p < 0.05). The mRNA expression quantities of SDH and LDH gene was higher via RT-PCR method. However, the expression of Ca(2+) ATPase remains similar. In conclusion, appropriate oral administration of L-carnitine of 25 mg/pigeon/day will result in an improvement of muscles related to flying.
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- 2013
12. Mechanism and Kinetics of Elemental Sulfur Oxidation by Thiobacillus Thiooxidans in Batch Fermenter
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J. C. C. Su, R. Y. Peng, Y. C. Cheng, and D. Y. Lo
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inorganic chemicals ,Tetrathionate ,Thiosulfate ,ved/biology ,ved/biology.organism_classification_rank.species ,Inorganic chemistry ,chemistry.chemical_element ,General Medicine ,Biodegradation ,Sulfur ,Thiobacillus ,chemistry.chemical_compound ,chemistry ,Sulfite ,Bioleaching ,Environmental Chemistry ,Sulfate ,Waste Management and Disposal ,Water Science and Technology - Abstract
The sulfur oxidative capability of Thiobacillus thiooxidans (T.t.) has been investigated with respect to bioleaching capability for cadmium-contaminated soil. A preliminary mechanism was deduced in this study. The sulfur is simultaneously oxidized to thiosulfate and sulfite by action of T.t. The thiosulfate exibits growth inhibitory effect and consequently the pathway from sulfur to thiosulfate is considered to be strictly energy-production-associated while the pathway from sulfur to sulfite was found both energy-producing and growth-associated. Kinetic study analysis showed that the biomass production follows the Monod kinetic model with inhibition, whereas the sulfate production follows the same Monod model without inhibition.
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- 1999
13. Prognostic significance of plasma Epstein-Barr virus (EBV) DNA level in patients with locally advanced head and neck carcinoma treated with concurrent cisplatin and concomitant boost radiotherapy (CBRT)
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A. K. Chan, K. T. Wong, A. D. King, Alexander C. Vlantis, G. M. Tse, E. P. Hui, M. K. Kam, D. Y. Lo, K. H. Yu, and A. T. Chan
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Cisplatin ,Oncology ,Cancer Research ,medicine.medical_specialty ,Pathology ,business.industry ,Cartilage ,medicine.medical_treatment ,Locally advanced ,medicine.disease_cause ,Epstein–Barr virus ,Radiation therapy ,Real-time polymerase chain reaction ,medicine.anatomical_structure ,Internal medicine ,medicine ,Clinical endpoint ,Stage (cooking) ,business ,medicine.drug - Abstract
20003 Background: EBV DNA is detectable in the plasma in most patients (Pts) with lymphoepithelial carcinoma (LECA) and in some Pts with squamous cell carcinoma (SCC) of the HN. We investigated the prognostic significance of plasma EBV DNA level in a prospective phase II trial of concurrent cisplatin and CBRT for locally advanced HN carcinomas. Methods: Eligibility criteria included newly-diagnosed SCC or LECA of non-nasopharyngeal HN sites; stage III or IV disease; ECOG performance status ≤ 1; and age ≤ 70 years. Plasma EBV DNA levels were measured by real-time quantitative polymerase chain reaction (PCR) before treatment and at 6 weeks post-treatment. Pre-treatment gross tumor volume (GTV) was measured on CT, and invasion of bone and cartilage was assessed on CT and MRI. Cisplatin 40–50 mg/m2 was given on days 1, 8, 15 and 22 of CBRT. Radiotherapy consisted of 54 Gy/30 fractions/6 weeks and a concomitant boost (18 Gy/12 fractions) in the last 12 treatment days. The primary endpoint was overall survival (OS) and the secondary endpoint was progression-free survival (PFS). Survival curves were compared by the log-rank test and multivariate analysis was performed with Cox regression. Results: Between March 2001 and January 2005, 46 Pts were recruited (36 with SCC and 10 with LECA). Thirty-four Pts had stage III and 12 had stage IV disease. Pre-treatment plasma EBV DNA level was > 0 copy/ml in all Pts with LECA (range, 37 - 211737 copies/ml) and in 8 Pts with SCC (range, 10 - 48734 copies/ml). Ten Pts had plasma EBV DNA level > 0 copy/ml at 6 weeks post-treatment. With a median follow-up of 1.6 years, the 1-year OS rate was 87.7 % and 1-year PFS rate was 68.3%. On multivariate analysis, plasma EBV DNA > 0 copy/ml at 6 weeks post-treatment was the only independent predictive factor of decreased OS [hazard ratio (HR) 3.59, p = 0.04] for the entire group. In the subgroup of Pts with SCC, pre-treatment EBV DNA > 0 copy/ml was the only independent predictive factor of decreased locoregional PFS (HR 7.08, p = 0.03). Conclusions: Plasma EBV DNA level is a prognostic factor in Pts with locally advanced HN SCC and LECA. Further studies are warranted to confirm the finding and to elucidate its biological basis. No significant financial relationships to disclose.
- Published
- 2006
14. Codon optimization and improved delivery/immunization regimen enhance the immune response against wild-type and drug-resistant HIV-1 reverse transcriptase, preserving its Th2-polarity
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A. A. Latanova, S. Petkov, A. Kilpelainen, J. Jansons, O. E. Latyshev, Y. V. Kuzmenko, J. Hinkula, M. A. Abakumov, V. T. Valuev-Elliston, M. Gomelsky, V. L. Karpov, F. Chiodi, B. Wahren, D. Y. Logunov, E. S. Starodubova, and M. G. Isaguliants
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Medicine ,Science - Abstract
Abstract DNA vaccines require a considerable enhancement of immunogenicity. Here, we optimized a prototype DNA vaccine against drug-resistant HIV-1 based on a weak Th2-immunogen, HIV-1 reverse transcriptase (RT). We designed expression-optimized genes encoding inactivated wild-type and drug-resistant RTs (RT-DNAs) and introduced them into mice by intradermal injections followed by electroporation. RT-DNAs were administered as single or double primes with or without cyclic-di-GMP, or as a prime followed by boost with RT-DNA mixed with a luciferase-encoding plasmid (“surrogate challenge”). Repeated primes improved cellular responses and broadened epitope specificity. Addition of cyclic-di-GMP induced a transient increase in IFN-γ production. The strongest anti-RT immune response was achieved in a prime-boost protocol with electroporation by short 100V pulses done using penetrating electrodes. The RT-specific response, dominated by CD4+ T-cells, targeted epitopes at aa 199–220 and aa 528–543. Drug-resistance mutations disrupted the epitope at aa 205–220, while the CTL epitope at aa 202–210 was not affected. Overall, multiparametric optimization of RT strengthened its Th2- performance. A rapid loss of RT/luciferase-expressing cells in the surrogate challenge experiment revealed a lytic potential of anti-RT response. Such lytic CD4+ response would be beneficial for an HIV vaccine due to its comparative insensitivity to immune escape.
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- 2018
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15. Safety and immunogenicity of GamEvac-Combi, a heterologous VSV- and Ad5-vectored Ebola vaccine: An open phase I/II trial in healthy adults in Russia
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I. V. Dolzhikova, O. V. Zubkova, A. I. Tukhvatulin, A. S. Dzharullaeva, N. M. Tukhvatulina, D. V. Shcheblyakov, M. M. Shmarov, E. A. Tokarskaya, Y. V. Simakova, D. A. Egorova, D. N. Scherbinin, I. L. Tutykhina, A. A. Lysenko, A. V. Kostarnoy, P. G. Gancheva, T. A. Ozharovskaya, B. V. Belugin, L. V. Kolobukhina, V. B. Pantyukhov, S. I. Syromyatnikova, I. V. Shatokhina, T. V. Sizikova, I. G. Rumyantseva, A. F. Andrus, N. V. Boyarskaya, A. N. Voytyuk, V. F. Babira, S. V. Volchikhina, D. A. Kutaev, A. N. Bel'skih, K. V. Zhdanov, S. M. Zakharenko, S. V. Borisevich, D. Y. Logunov, B. S. Naroditsky, and A. L. Gintsburg
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ad5 ,ebola ,ebola virus disease ,heterologous vaccination ,prime-boost ,vaccine ,vsv ,zebov ,Immunologic diseases. Allergy ,RC581-607 ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Ebola hemorrhagic fever, also known as Ebola virus disease or EVD, is one of the most dangerous viral diseases in humans and animals. In this open-label, dose-escalation clinical trial, we assessed the safety, side effects, and immunogenicity of a novel, heterologous prime-boost vaccine against Ebola, which was administered in 2 doses to 84 healthy adults of both sexes between 18 and 55 years. The vaccine consists of live-attenuated recombinant vesicular stomatitis virus (VSV) and adenovirus serotype-5 (Ad5) expressing Ebola envelope glycoprotein. The most common adverse event was pain at the injection site, although no serious adverse events were reported. The vaccine did not significantly impact blood, urine, and immune indices. Seroconversion rate was 100 %. Antigen-specific IgG geometric mean titer at day 42 was 3,277 (95 % confidence interval 2,401–4,473) in volunteers immunized at full dose. Neutralizing antibodies were detected in 93.1 % of volunteers immunized at full dose, with geometric mean titer 20. Antigen-specific response in peripheral blood mononuclear cells was also detected in 100 % of participants, as well as in CD4+ and CD8+ T cells in 82.8 % and 58.6 % of participants vaccinated at full dose, respectively. The data indicate that the vaccine is safe and induces strong humoral and cellular immune response in up to 100 % of healthy adult volunteers, and provide a rationale for testing efficacy in Phase III trials. Indeed, the strong immune response to the vaccine may elicit long-term protection. This trial was registered with grls.rosminzdrav.ru (No. 495*), and with zakupki.gov.ru (No. 0373100043215000055).
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- 2017
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16. Endogenous retrovirus: from fundamental studies to etiotropic therapy of multiple sclerosis
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M. N. Zakharova, D. Y. Logunov, I. A. Kochergin, and I. S. Bakulin
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endogenous retroviruses ,multiple sclerosis ,demyelination ,etiotropic therapy ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Retroviruses are a single-stranded RNA viruses that introducetheir genes into host cells genome. Genes of retroviruses compose9.3% of human genome. These genes may influence humangenome activity by changing its structure and stability, introducingregulatory elements and expression of retroviral genes.Recently role of endogen retroviruses in human disease is studied.This article presents an overview of the role of retroviruses inthe development of multiple sclerosis and potential approachesto etiotropic therapy.
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- 2017
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17. Energy cost to sputter an atom from a surface in keV ion bombardment processes
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Nicholas Winograd, Don E. Harrison, Barbara J. Garrison, Mark H. Shapiro, D. Y. Lo, and T. A. Tombrello
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Surface (mathematics) ,Chemistry ,Surfaces and Interfaces ,Condensed Matter Physics ,Ion bombardment ,Surfaces, Coatings and Films ,Ion ,Enthalpy of sublimation ,Sputtering ,Atom ,Materials Chemistry ,Energy cost ,Astrophysics::Earth and Planetary Astrophysics ,Atomic physics ,Energy (signal processing) - Abstract
We propose that the energy cost to remove one atom from the surface during ion bombard-ment is larger than the surface binding energy or bulk heat of sublimation. It is this value of the energy cost that is appropriate for use in analytic models of the sputtering process.
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- 1987
18. Secondary electron emission from the entrance and exit surfaces of thin carbon foils under fast ion bombardment
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D.Z. Zhang, H.S. Toh, R.P. Livi, Marcus H. Mendenhall, C.R. Shi, D. Y. Lo, and T. A. Tombrello
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Nuclear and High Energy Physics ,Ion beam deposition ,Yield (engineering) ,Ion beam ,Physics::Plasma Physics ,Chemistry ,Secondary emission ,Electron ,Stopping power ,Atomic physics ,Instrumentation ,Secondary electrons ,Ion - Abstract
The total secondary electron emission (SEE) yield from the entrance and exit surfaces of thin carbon foils under fast ion (^(16)O, ^(19)F, ^(35)Cl) bombardment has been measured as a function of the ion energy and the ion beam current intensity. Using a retarding field, the energy distribution of secondary electrons integrated over almost all angles of emission in the backward and forward directions has also been measured. It is found that total forward emission is larger than backward emission by factors of up to 2.5, 2.7 and 3.4 for ^(16)O^(+3), ^(19)F^(+3) and ^(35)Cl^(+5), respectively. It is suggested that the enhancement of forward SEE may be partly due to effects from the instantaneous charge state of the heavy ion beam in the solid in addition to the binary collisions of the projectile with individual electrons in the target. It is also shown that the total SEE yield from the entrance and exit surfaces of the target foils decreases with ion beam current intensity; this may be a beam-induced temperature effect. The total SEE yield in both the forward and backward directions is less sensitive to surface conditions for high velocity ions than for low velocity ions and the total yield from both surfaces of the foils is proportional to the ion stopping power in the target, where the constant of proportionality depends on the properties of material.
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- 1985
19. Simulation of sputtering from liquid Cu targets
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Peter K. Haff, D. Y. Lo, Mark H. Shapiro, and T. A. Tombrello
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Nuclear and High Energy Physics ,Materials science ,chemistry.chemical_element ,Copper ,Ion ,Molecular dynamics ,chemistry ,Cascade ,Sputtering ,Yield (chemistry) ,Melting point ,Atomic physics ,Instrumentation ,Eutectic system - Abstract
The sputtering of Cu atoms from liquid targets by normally incident 5 keV Ar^+ ions was simulated using the multiple interaction molecular dynamics technique. Yields, energy distributions, and angular distributions of sputtered atoms were obtained at several temperatures slightly above and below the experimental melting point of copper. In all cases the resulting angular distributions of ejected atoms peaked more sharply than the cos θ behavior predicted by linear cascade theory. The ratio of yields from individual layers of the liquid targets, and the energy and angular distributions of ejected atoms generally were found to be similar to those obtained in previous simulations with solid Cu targets. Our results also are in qualitative agreement with Dumke's measurements of angular distributions and layer yield ratios of sputtered atoms from liquid Ga-In eutectic alloy targets. In particular, no marked changes in yields or energy distributions were observed when the temperature of the target was lowered below the nominal melting point of copper. The angular distributions were found to broaden with increasing temperature.
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- 1986
20. Liquid target generation techniques in molecular dynamics studies of sputtering
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D. Y. Lo, T. A. Tombrello, and Mark H. Shapiro
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Momentum ,Nuclear and High Energy Physics ,Molecular dynamics ,Yield (engineering) ,Reflection (mathematics) ,Chemistry ,Sputtering ,Free surface ,Boundary value problem ,Atomic physics ,Boundary layer thickness ,Instrumentation - Abstract
Techniques of generating liquid targets for molecular dynamics studies of sputtering were investigated in systems consisting of 603 Cu atoms. The effects of different boundary conditions on sputtering yield, layer yield ratio, energy distribution, and polar angular distribution of ejected particles were found to be important. A box boundary condition and a semiperiodic boundary condition were considered. The box boundary conditions required the particles to experience pure reflection at the boundaries, while semiperodic boundary conditions demanded position and momentum periodicity in the two dimensions defined by the surface of the target. Sputtering from the target generated with a box boundary condition resulted in a 60% higher total yield, a slightly higher first layer yield ratio, a 60% lower surface binding energy, and a sharper polar angular distribution than from the target generated under a semiperodic boundary condition at the same temperature. Since the results obtained with the semiperiodic boundary conditions are in better agreement with experimental sputtering results, we have concluded that the semiperiodic boundary conditions produces a target that better represents the free surface of real liquid systems.
- Published
- 1986
21. Theoretical studies of ion bombardment: Many-body interactions
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Don E. Harrison, T. A. Tombrello, Barbara J. Garrison, D. Y. Lo, Mark H. Shapiro, and Nicholas Winograd
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Chemistry ,chemistry.chemical_element ,Surfaces and Interfaces ,Condensed Matter Physics ,Copper ,Spectral line ,Charged particle ,Surfaces, Coatings and Films ,Ion ,Metal ,Many-body problem ,Molecular dynamics ,Sputtering ,visual_art ,visual_art.visual_art_medium ,Atomic physics ,Caltech Library Services - Abstract
Many-body forces obtained by the embedded-atom method are incorporated into the description of low-energy collisions and surface ejection processes in molecular dynamics simulations of sputtering from metal targets. Bombardment of small, single-crystal Cu targets (400–500 atoms) in three different orientations ({100}, {110}, {111}) by 5-keV Ar + ions have been simulated. The results are compared to simulations using purely pairwise additive interactions. Significant differences in the spectra of ejected atoms are found.
- Published
- 1988
22. Many-body embedded-atom potential for describing the energy and angular distributions if Rh atoms desorbed from ion-bombarded Rh{111}
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Don E. Harrison, D. Y. Lo, T. A. Tombrello, C. T. Reimann, D. M. Deaven, Barbara J. Garrison, Mark H. Shapiro, Nicholas Winograd, Naval Postgraduate School (U.S.), and Physics and Chemistry
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Crystal ,Materials science ,Sputtering ,Desorption ,Atom ,Atomic physics ,Kinetic energy ,Pair potential ,Spectral line ,Caltech Library Services ,Ion - Abstract
In this paper, we show that many-body interactions are important for describing the energy- and angle-resolved distributions of neutral Rh atoms ejected from keV-ion-bombarded Rh{111}. We compare separate classical-dynamics simulations of the sputtering process assuming either a many-body potential or a pairwise additive potential. The many-body potential is constructed using the embedded-atom method to describe equilibrium properties of the crystal, parameters from the Moliere potential to describe close encounters between energized atoms, and parameters from a Rh(2) potential to aid the description of the desorption event. The most dramatic difference between the many-body potential and the pair potential is in the predicted kinetic energy distributions. The pair-potential kinetic energy distribution peaks at ~2 eV, whereas the many-body potential predicts a broader peak at ~4 eV, giving much better agreement with experiment. This difference between the model potentials is due to the predicted nature of the attractive interaction in the surface region through which all ejecting particles pass. Variations of the many-body potential parameters are examined in order to ascertain their effect on the predicted energy and singular distributions. A specific set of parameters has been found which leads to excellent agreement with recent experimental trajectory measurement of desorbed Rh atoms. Approved for public release; distribution is unlimited.
- Published
- 1988
23. Molecular Dynamics Simulation of Sputtering with Mmany-Body Interactions
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Don E. Harrison, D. Y. Lo, T. A. Tombrello, and Mark H. Shapiro
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Metal ,Molecular dynamics ,Materials science ,Low energy ,Sputtering ,Chemical physics ,visual_art ,visual_art.visual_art_medium ,Single crystal ,Spectral line ,Ion - Abstract
Many-body forces obtained by the Embedded-Atom Method (EAM) [41 are incorporated into the description of low energy collisions and surface ejection processes in molecular dynamics simulations of sputtering from metal targets. Bombardments of small, single crystal Cu targets (400–500 atoms) in three different orientations ({100}, {110}, {111}) by 5 keV Ar+ ions have been simulated. The results are compared to simulations using purely pair-wise additive interactions. Significant differences in the spectra of ejected atoms are found.
- Published
- 1988
24. Computer Simulation of Sputtering from Two Component Liquid Metal Targets
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Mark H. Shapiro, T. A. Tombrello, and D. Y. Lo
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Liquid metal ,Molecular dynamics ,Materials science ,chemistry ,Sputtering ,Monolayer ,Melting point ,chemistry.chemical_element ,Gallium ,Molecular physics ,Indium ,Eutectic system - Abstract
The sputtering of In and Ga atoms from a “liquid” target composedof gallium coveredby a surface monolayer of indium by incident 5 keV Ar+ ions was simulated using the multiple interaction molecular dynamics technique. Yields, energy distributions, and angular distributions of sputtered atoms were obtained at a temperature above the melting point for the eutectic alloy. Similar information was obtained for a pure gallium and a pure indium target. Our results for layer yield ratios and angular distributions are in good qualitative agreement with Dumke's experimental data for the Ar+, In-Ga system. Absolute yields, however, were found to be sensitive to the detailed nature of the two-body potentials used to describe the atom-atom interactions.
- Published
- 1985
25. Comparison of the Association of Age with the Infection of Salmonella and Salmonella enterica Serovar Typhimurium in Pekin Ducks and Roman Geese.
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C.-y. Yu, C. Chu, S.-j. Chou, M.-r. Chao, C.-M. Yeh, D.-Y. Lo, Y.-C. Su, Horng, Y.-M., Weng, B.-C., Tsay, J.-G., and Huang, K.-C.
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DUCKS , *GEESE , *SALMONELLA infections in poultry , *BACTERIAL diseases , *VETERINARY medicine , *POULTRY - Abstract
Nontyphoid Salmonella have a broad host range in poultry and mammals, and serovar Typhimurium is a threat to public health. In this study, normal and sick ducks and geese were collected from 12 farms in Taiwan to investigate the age-associated infection of Salmonella and Salmonella Typhimurium in Roman geese (Anser anser domesticus) and Pekin ducks (Anas platyrhynchos domesticus). In normal birds, the prevalence of Salmonella differed between species, and with age [e.g., 1-wk group, 37.5% (30/80) for ducks and 5.2% (6/116) for goslings (P < 0.05) vs. 4-wk group, 1% (1/96) for ducks and 12.1% (21/174) for geese]. Salmonella Typhimurium was identified from the visceral organs of moribund young geese suffering with colibacillosis and riemerellosis isolated from 2 goose farms (farm A and B, respectively). At farm B, 22.9% (27/118) of 4-wk geese with diarrhea were Salmonella Typhimurium-positive compared with 4.6% (8/174) of 4-wk normal geese. All Salmonella Typhimurium strains except one harbored a 94.7-kb virulence plasmid. Subcutaneous injection of Salmonella Typhimurium isolate 91NGL1 resulted in different clinical signs and pathogenesis between ducks and geese. In addition, the mean infectivity dose ratios of ducks to geese were 3.2 and 85.0 for 4- and 12-d birds, respectively, suggesting that goslings were more susceptible to Salmonella Typhimurium and resistance to Salmonella Typhimurium increased with age, especially for ducks. Therefore, Salmonella Typhimurium infection should be more common in goose farms than in duck farms, especially in the younger birds. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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