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Three Li-rich K giants: IRAS 12327-6523, IRAS 13539-4153, and IRAS 17596-3952
We report on spectroscopic analyses of three K giants previously suggested to
be Li-rich: IRAS 12327-6523, IRAS 13539-4153, and IRAS 17596-3952.
High-resolution optical spectra and the LTE model atmospheres are used to
derive the stellar parameters: (, log , [Fe/H]), elemental
abundances, and the isotopic ratio C/C. IRAS 13539-4153 shows an
extremely high Li abundance of (Li) 4.2, a value ten
times more than the present Li abundance in the local interstellar medium. This
is the third highest Li abundance yet reported for a K giant. IRAS 12327-6523
shows a Li abundances of (Li) 1.4. IRAS 17596-3952 is a
rapidly rotating ( 35 km s) K giant with
(Li) 2.2. Infrared photometry which shows the presence
of an IR excess suggesting mass-loss. A comparison is made between these three
stars and previously recognized Li-rich giants.Comment: 17 pages, 6 figures, accepted for A
NMR and LDA evidence for spiral magnetic order in the chain cuprate LiCu2O2
We report on {6,7}Li nuclear magnetic resonance measurements of the
spin-chain compound LiCu2O2 in the paramagnetic and magnetically ordered
states. Below T about 24 K the NMR lineshape presents a clear signature of
incommensurate (IC) static modulation of the local magnetic field consistent
with an IC spiral modulation of the magnetic moments. {7}Li NMR reveals strong
phason-like dynamical fluctuations extending well below 24 K. We hypothesize
that a series of phase transitions at 24.2, 22.5, and 9 K reflects a "Devil's
staircase" type behavior generic for IC systems. LDA based calculations of
exchange integrals reveal a large in-chain frustration leading to a magnetical
spiral.Comment: 4 pages, 4 figure
On a Rapid Lithium Enrichment and Depletion of K Giant Stars
A model scenario has recently been introduced to explain the presence of very
strong Li lines in the spectra of some low mass K giant stars (de la Reza et
al. 1996). In this scenario all ordinary, Li poor, K giants become Li rich
during a short time () when compared to the red giant phase of 5
10^7 yr. In this ``Li period'', a large part of the stars are associated with
an expanding thin circumstellar shell supposedly triggered by an abrupt
internal mixing mechanism resulting in a surface new ^7Li enrichment. This
letter presents near 40 Li rich K giants known up to now. The distribution of
these Li rich giants, along with other 41 observed K giants that have shell,
but are not Li rich, in a color-color IRAS diagram confirms this scenario,
indicating, also as a new result, that a rapid Li depletion takes place on a
time scale of between and 10^5 yr. This model explains the problem
of the presence of K giants with far infrared excesses presented by Zuckerman
et al. (1995). Other present and future tests of this scenario are briefly
discussed.Comment: 14 pages, 2 figure
Reserve Li/SOC12 Battery Safety Testing
A reserve Lithium/Thionyl Chloride Battery concept is developed and undergoing feasibility testing in terms of performance, safety and abusive conditions. The feasibility of employing a battery of this type to replace thermal batteries in certain applications is demonstrated. Excellent performance of a Li/SOCl2 reserve battery is obtained across the temperature range from 0 C to +44 C. Performance improvement over the thermal battery usage is greater by a factor of 3 when discharge time and energy density are compared. Performance over an expanded temperature range is also possible. Safety and abusive testing is accomplished successfully on a series of five units. Further performance improvements can be achieved with regard to battery weight and volume reductions
Magnetism in purple bronze LiMoO
Muon spin relaxation measurements around the 25 K metal-insulator transition
in LiMoO elucidate a profound role of disorder as a possible
mechanism for this transition. The relaxation rate and the muon Knight
shift are incompatible with the transition to a SDW state and thus exclude it.Comment: pages 2, fig 2, The conf. on strongly correlated electron systems,
SCES 2004, German
Прогнозирование светопропускания модифицированных стекол
На основі методів математичної статистики розглянуті питання прогнозування світлопропускання стекол з модифікованою поверхнею. Встановлено, що на світлопропускання цих стекол значний вплив оказує не вміст в ПУР K₂O, Li₂O, SiO₂, а співвідношення Li₂O/SiO₂.On the basis of methods of mathematical statistics the questions of prognossng of lightadmission glasses are considered with the modifiedsurface. It is set that on light admission of the seglasses the considerable influencing is rendered by not maintenance in FMS of K₂O, Li₂O, SiO₂, and correlation of Li₂O/SiO₂
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Site-specific mutations in a minimal voltage-dependent K+ channel alter ion selectivity and open-channel block.
MinK is a small membrane protein of 130 amino acids with a single potential membrane-spanning alpha-helical domain. Its expression in Xenopus oocytes induces voltage-dependent, K(+)-selective channels. Using site-directed mutagenesis of a synthetic gene, we have identified residues in the hydrophobic region of minK that influence both ion selectivity and open-channel block. Single amino acid changes increase the channel's relative permeability for NH4+ and Cs+ without affecting its ability to exclude Na+ and Li+. Blockade by two common K+ channel pore blockers, tetraethylammonium and Cs+, was also modified. These results suggest that an ion selectivity region and binding sites for the pore blockers within the conduction pathway have been modified. We conclude that the gene encoding minK is a structural gene for a K+ channel protein
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