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71.
N. J. Ncapayi S. M. Mullins M. Benatar E. Gueorgueiva J. J. Lawrie G. K. Mabala S. Mukherjee S. H. T. Murray K. P. Mutshena R. T. Newman J. F. Sharpey-Schafer F. D. Smit P. Vymers 《The European Physical Journal A - Hadrons and Nuclei》2005,23(2):265-269
Excited states in 175Yb, 176Yb and 177Yb were populated via the bombardment of a 176Yb target with a 750 MeV 136Xe beam. Gamma-ray decays from these states were measured with the AFRODITE multi-detector spectrometer. The rotational band
previously assigned to the ground state of 177Yb has been reassigned to the first-excited state of 175Yb. A new rotational band based on the ground state of 177Yb is presented, and the band based on the Kπ = 4- two-quasiparticle state in 176Yb has been identified. Also a candidate for the rotational band based on the Kπ = 8-, T1/2 = 11.4(3) s two-quasiparticle state in 176Yb has been found. Comparisons of gK values derived from in-band branching ratios are consistent with the ν9/2+[624] assignment to the ground state of 177Yb, the ν2{9/2+[624] ⊗ 1/2-[510]} assignment to the Kπ = 4- state and with the ν2{9/2+[624] ⊗ 7/2-[514]} assignment to the Kπ = 8- metastable excited state in 176Yb. 相似文献
72.
Minimization of Fragmentation and Aggregation by Laser Desorption Laser Ionization Mass Spectrometry
Qinghao Wu Andrew E. Pomerantz Oliver C. Mullins Richard N. Zare 《Journal of the American Society for Mass Spectrometry》2013,24(7):1116-1122
Measuring average quantities in complex mixtures can be challenging for mass spectrometry, as it requires ionization and detection with nearly equivalent cross-section for all components, minimal matrix effect, and suppressed signal from fragments and aggregates. Fragments and aggregates are particularly troublesome for complex mixtures, where they can be incorrectly assigned as parent ions. Here we study fragmentation and aggregation in six aromatic model compounds as well as petroleum asphaltenes (a naturally occurring complex mixture) using two laser-based ionization techniques: surface assisted laser desorption ionization (SALDI), in which a single laser desorbs and ionizes solid analytes; and laser ionization laser desorption mass spectrometry (L2MS), in which desorption and ionization are separated spatially and temporally with independent lasers. Model compounds studied include molecules commonly used as matrices in single laser ionization techniques such as matrix assisted laser desorption ionization (MALDI). We find significant fragmentation and aggregation in SALDI, such that individual fragment and aggregate peaks are typically more intense than the parent peak. These fragment and aggregate peaks are expected in MALDI experiments employing these compounds as matrices. On the other hand, we observe no aggregation and only minimal fragmentation in L2MS. These results highlight some advantages of L2MS for analysis of complex mixtures such as asphaltenes. Figure
? 相似文献
73.
Amran AB Majid Aznan Fazli Ismail Muhamad Samudi Yasir Redzuwan Yahaya Ismail Bahari 《Journal of Radioanalytical and Nuclear Chemistry》2013,297(2):277-284
Previous studies have shown that the natural radioactivity contained in building materials have significantly influenced the dose rates in dwelling. Exposure to natural radiation in building has been of concerned since almost 80 % of our daily live are spend indoor. Thus, the aim of the study is to assess the radiological risk associated by natural radioactivity in soil based building materials to dwellers. A total of 13 Portland cement, 46 sand and 43 gravel samples obtained from manufacturers or bought directly from local hardware stores in Peninsular of Malaysia were analysed for their radioactivity concentrations. The activity concentrations of 226Ra, 232Th and 40K in the studied building materials samples were found to be in the range of 3.7–359.3, 2.0–370.8 and 10.3–1,949.5 Bq kg?1 respectively. The annual radiation dose rates (μSv year?1) received by dwellers were evaluated for 1 to 50 years of exposure using Resrad-Build Computer Code based on the activity concentration of 226Ra, 232Th and 40K found in the studied building material samples. The rooms modelling were based on the changing parameters of concrete wall thickness and the room dimensions. The annual radiation dose rates to dwellers were found to increase annually over a period of 50 years. The concrete thicknesses were found to have significantly influenced the dose rates in building. The self-absorption occurred when the concrete thickness was thicker than 0.4 m. Results of this study shows that the dose rates received by the dwellers of the building are proportional to the size of the room. In general the study concludes that concrete building materials; Portland cements, sands, and gravels in Peninsular of Malaysia does not pose radiological hazard to the building dwellers. 相似文献
74.
Sudharshan Prabhu Rekha PD Chiu-Chung Young Asif Hameed Shih-Yao Lin Arun AB 《Applied biochemistry and biotechnology》2013,171(4):817-831
Zeaxanthin carotenoids are class of commercially important natural products and diverse biomolecules produced by plants and many microorganisms. Bacteria often produce a cocktail of polar and nonpolar carotenoids limiting their industrial applications. Marine members of the family Flavobacteriaceae are known to produce potential carotenoids such as astaxanthin and zeaxanthin. A few bacterial species have been reported for the predominant production zeaxanthin. Here, we report the molecular identification of the zeaxanthin as a major carotenoid produced by two novel bacteria (YUAB-SO-11 and YUAB-SO-45) isolated from sandy beaches of South West Coast of India and the effect of carbon sources on the production of zeaxanthin. The strains were identified based on the 16S rRNA gene sequencing as a member of genus Muricauda. The closest relatives of YUAB-SO-11 and YUAB-SO-45 were Muricauda aquimarina (JCM 11811T) (98.9 %) and Muricauda olearia (JCM 15563T) (99.2 %), respectively, indicating that both of these strains might represent a novel species. The highest level of zeaxanthin production was achieved (YUAB-SO-11, 1.20?±?0.11 mg g?1) and (YUAB-SO-45, 1.02?±?0.13 mg g?1) when cultivated in marine broth supplemented with 2 % NaCl (pH 7) and incubated at 30 °C. Addition of 0.1 M glutamic acid, an intermediate of citric acid cycle, enhanced the zeaxanthin production as 18 and 14 % by the strains YUAB-SO-11 and YUAB-SO-45 respectively. The zeaxanthin showed in vitro nitric oxide scavenging, inhibition of lipid peroxidation, and 2,2-diphenyl-1-picryl hydrazyl scavenging activities higher than the commercial zeaxanthin. The results of this study suggest that two novel strains YUAB-SO-11 and YUAB-SO-45 belonging to genus Muricauda produce zeaxanthin as a predominant carotenoid, and higher production of zeaxanthin was achieved on glutamic acid supplementation. The pigment showed good in vitro antioxidant activity, which can be exploited further for commercial applications. 相似文献
75.
The condensation between dienophiles and α,β-unsaturated hydrazone azadienes was previously reported to afford piperidines. During an attempt to adapt this reaction to the preparation of piperidine-based conformationally restricted analogs of glutamate, it was discovered that the electrophile, dimethyl oxoglutaconate (DOG) led to highly substituted dihydropyrans in 20-50% yield. The unexpected pyran product likely results from an initial 1,4-addition of the hydrazone to the oxoglutaconate followed by intramolecular cyclization of the resultant enolate oxygen to the α,β-unsaturated iminium ion. Further manipulations afford substituted tetrahydropyran 6-methamino-2,4-dicarboxylic acids. 相似文献
76.
A. Lopez-Martens T. Wiborg-Hagen K. Hauschild M.L. Chelnokov V.I. Chepigin D. Curien O. Dorvaux G. Drafta B. Gall A. Görgen M. Guttormsen A.V. Isaev I.N. Izosimov A.P. Kabachenko D.E. Katrasev T. Kutsarova A.N. Kuznetsov A.C. Larsen O.N. Malyshev A. Minkova S. Mullins H.T. Nyhus D. Pantelica J. Piot A.G. Popeko S. Saro N. Scintee S. Siem N.U.H. Syed E.A. Sokol A.I. Svirikhin A.V. Yeremin 《Nuclear Physics A》2011
New high-statistics data have been obtained on the decay properties of 253No and its daughters using the reaction 207Pb(48Ca, 2n)253No. This was made possible thanks to an improved transmission of fusion–evaporation residues through the VASSILISSA recoil separator and an increased efficiency of the GABRIELA detector setup. The decay schemes of 253No and 249Fm have been revisited. The known level scheme of 249Fm has been confirmed, including a new level at 669 keV excitation energy. The observation of L X-rays in coincidence with the α decay of 249Fm gives additional support to the ground-state configuration of 1/2+[631] instead of 5/2+[622] for 245Cf. In both 249Fm and 245Cf, the interpretation of the data has been checked by comparing experimental α-particle and γ-ray spectra with realistic simulations of the decay cascades and of the interaction of particles and photons in the detectors of GABRIELA. The population of a 0.7 ms isomeric state attributed to 253No is confirmed by an α-tagged calorimetric measurement and the corresponding γ and electron decay spectra are presented. Possible evidence for more than one isomer is given and a tentative partial decay scheme is discussed in the light of the available experimental data, systematics and theoretical expectations. 相似文献
77.
F. Eimer F. Weise A. Merli S. Birkner F. Sauer L. W?ste A. Lindinger R. A?ano?lu C. P. Koch W. Salzmann T. Mullins S. G?tz R. Wester M. Weidemüller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(3):711-714
We present spectrally resolved pump-probe experiments on the photoassociation of ultracold rubidium atoms with shaped ultrashort
laser pulses. The pump pulse causes a free-bound transition leading to a coherent transient signal of rubidium molecules in
the first excited state. In order to achieve a high frequency resolution the bandwidth of the pump pulse is reduced to a few
wavenumbers. The frequency dependence of the transient signal close to the D1 atomic resonance is investigated for characteristic
pump-probe delay times. The observed spectra, which show a pronounced dip for pump-probe coincidence, are interpreted using
quantum dynamical calculations. 相似文献
78.
A. I. Svirikhin A. V. Yeremin A. V. Andreev I. N. Izosimov A. V. Isaev A. N. Kuznetsov A. A. Kuznetsova O. N. Malyshev A. G. Popeko Y. A. Popov E. A. Sokol M. L. Chelnokov V. I. Chepigin T. M. Schneidman B. Gall O. Dorvaux P. Brione K. Hauschild A. Lopez-Martenz K. Rezynkina S. Mullins P. Jones P. Mosat B. Andel Z. Kalaninova M. Z. Asfari N. Yoshihiro J. Piot E. Stefanova D. Tonev 《Bulletin of the Russian Academy of Sciences: Physics》2018,82(6):632-636
series of experiments performed in 2014–2015 using the SHELS separator and a beam of multicharged ions from the U-400 accelerator at the Flerov Laboratory of Nuclear Reactions (Joint Institute for Nuclear Research) in Dubna is described. In preparation for a large program of experiments with a beam of highly charged ions of 50Ti, an experiment is performed to study the spontaneous fissioning (SF) of short-lived neutron-deficient isotope 256Rf formed in complete fusion reaction50Ti + 208Pb = 256Rf + 2n. The half-life of 256Rf is measured along with the probability of its SF decay. The average number of neutrons per one event of 256Rf SF (\(\bar v\)= 4.47 ± 0.09) is obtained for the first time. The results from experiments to study the SF of short-lived neutron-deficient isotopes synthesized in complete fusion reaction 48Ca + 204Pb → 252No* are presented as well. Two short-lived activities attributed to the SF of the ground and isomeric states of 250No are revealed. The half-life, total kinetic energies of fission fragments, and neutron multiplicities are measured for the obtained short-lived nuclei. The average numbers of neutrons per one SF event are \(\bar v\)= 4.38 ± 0.13 and \(\bar v\)= 3.90 ± 0.20, respectively, for SF activity with t1/2 = 5.1 ± 0.3 and t1/2 = 36 ± 3 μs. 相似文献
79.
80.
Liquid borne ultrafine particles have elsewhere been shown to pass through a packed column at rates varying with particle size. The process is termed “hydrodynamic chromatography”, since a separation of the particles according to size can thereby be achieved. Similar results are reported herein for larger particles suspended in liquid when the passageway, instead of being a packed column is a long, completely open, capillary tube. Particle transit time is a function of the logarithm of particle diameter. The underlying mechanism for the latter phenomena is believed to be that previously called the “tubular pinch effect” which arises from a balance of lateral forces within the flow field, but experimental results are not adequately described by any theory yet proposed. The open-tube discrimination process is designated “capillary hydrodynamic chromatography”. 相似文献