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Petrography and bulk composition of Miller Range 05035: a new lunar VLT gabbro
Miller Range (MIL) 05035 is a crystalline lunar mare gabbroic meteorite collected in Antarctica in 2005 [1]. It is an important new sample in the lunar meteorite (LM) collection as it is only one of ~8 to be classified as basaltic in nature. MIL 05035 is coarsely grained with large pyroxene grains ( 8mm) subophitically enclosing plagioclase grains ( 6mm), and accessory ilmenite, spinel, silica and sulphide phases
Elliptic supersonic jet morphology manipulation using sharp-tipped lobes
Elliptic nozzle geometry is attractive for mixing enhancement of supersonic
jets. However, jet dynamics, such as flapping, gives rise to high-intensity
tonal sound. We experimentally manipulate the supersonic elliptic jet
morphology by using two sharp-tipped lobes. The lobes are placed on either end
of the minor axis in an elliptic nozzle. The design Mach number and the aspect
ratio of the elliptic nozzle and the lobed nozzle are 2.0 and 1.65. The
supersonic jet is exhausted into ambient at almost perfectly expanded
conditions. Time-resolved schlieren imaging, longitudinal and cross-sectional
planar laser Mie-scattering imaging, planar Particle Image Velocimetry, and
near-field microphone measurements are performed to assess the fluidic behavior
of the two nozzles. Dynamic Mode and Proper Orthogonal Decomposition (DMD and
POD) analysis are carried out on the schlieren and the Mie-scattering images.
Mixing characteristics are extracted from the Mie-scattering images through the
image processing routines. The flapping elliptic jet consists of two dominant
DMD modes, while the lobed nozzle has only one dominant mode, and the flapping
is suppressed. Microphone measurements show the associated noise reduction. The
jet column bifurcates in the lobed nozzle enabling a larger surface contact
area with the ambient fluid and higher mixing rates in the near-field of the
nozzle exit. The jet width growth rate of the two-lobed nozzle is about twice
as that of the elliptic jet in the near-field, and there is a 40\% reduction in
the potential core length. Particle Image Velocimetry (PIV) contours
substantiate the results.Comment: 19 pages, 16 figures. Revised version submitted to Physics of Fluids
for peer review. URL of the Video files (Fig. 6 & Fig. 14) are given in the
text files (see in '/anc/*.txt'
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Compositional analysis of the very-low-Ti mare basalt component of NWA 773 and comparison with low-Ti basalts, LAP03632 and LAP02436
Abstract not available
Electrical and Magnetic behaviour of PrFeAsO0.8F0.2 superconductor
The superconducting and ground state samples of PrFeAsO0.8F0.2 and PrFeAsO
have been synthesised via easy and versatile single step solid state reaction
route. X-ray & Reitveld refine parameters of the synthesised samples are in
good agreement to the earlier reported value of the structure. The ground state
of the pristine compound (PrFeAsO) exhibited a metallic like step in
resistivity below 150K followed by another step at 12K. The former is
associated with the spin density wave (SDW) like ordering of Fe spins and later
to the anomalous magnetic ordering for Pr moments. Both the resistivity
anomalies are absent in case of superconducting PrFeAsO0.8F0.2 sample. Detailed
high field (up to 12Tesla) electrical and magnetization measurements are
carried out for superconducting PrFeAsO0.8F0.2 sample. The PrFeAsO0.8F0.2
exhibited superconducting onset (Tconset) at around 47K with Tc({\rho} =0) at
38K. Though the Tconset remains nearly invariant, the Tc({\rho} =0) is
decreased with applied field, and the same is around 23K under applied field of
12Tesla. The upper critical field (Hc2) is estimated from the Ginzburg Landau
equation (GL) fitting, which is found to be ~ 182Tesla. Critical current
density (Jc) being calculated from high field isothermal magnetization (MH)
loops with the help of Beans critical state model, is found to be of the order
of 103 A/cm2. Summarily, the superconductivity characterization of single step
synthesised PrFeAsO0.8F0.2 superconductor is presented.Comment: 15 Pages Text + Fig
Effect of Ni-doping on magnetism and superconductivity in Eu0.5K0.5Fe2As2
The effect of Ni-doping on the magnetism and superconductivity in
Eu0.5K0.5Fe2As2 has been studied through a systematic investigation of magnetic
and superconducting properties of Eu0.5K0.5(Fe1-xNix)2As2 (x = 0, 0.03, 0.05,
0.08 and 0.12) compounds by means of dc and ac magnetic susceptibilities,
electrical resistivity and specific heat measurements. Eu0.5K0.5Fe2As2 is known
to exhibit superconductivity with superconducting transition temperature Tc as
high as 33 K. The Ni-doping leads to a rapid decrease in Tc; Tc is reduced to
23 K with 3% Ni-doping, and 8% Ni-doping suppresses the superconductivity to
below 1.8 K. In 3% Ni-doped sample Eu0.5K0.5(Fe0.97Ni0.03)2As2
superconductivity coexists with short range ordering of Eu2+ magnetic moments
at Tm ~ 6 K. The suppression of superconductivity with Ni-doping is accompanied
with the emergence of a long range antiferromagnetic ordering with TN = 8.5 K
and 7 K for Eu0.5K0.5(Fe0.92Ni0.08)2As2 and Eu0.5K0.5(Fe0.88Ni0.12)2As2,
respectively. The temperature and field dependent magnetic measurements for x =
0.08 and 0.12 samples reflect the possibility of a helical magnetic ordering of
Eu2 moments. We suspect that the helimagnetism of Eu spins could be responsible
for the destruction of superconductivity as has been observed in Co-doped
EuFe2As2. The most striking feature seen in the resistivity data for x = 0.08
is the reappearance of the anomaly presumably due to spin density wave
transition at around 60 K. This could be attributed to the compensation of
holes (K-doping at Eu-site) by the electrons (Ni-doping at Fe site). The
anomaly associated with spin density wave further shifts to 200 K for x = 0.12
for which the electron doping has almost compensated the holes in the system.Comment: 9 pages, 10 figure
Metallic monoclinic phase in VO induced by electrochemical gating: in-situ Raman study
We report in-situ Raman scattering studies of electrochemically top gated
VO thin film to address metal-insulator transition (MIT) under gating. The
room temperature monoclinic insulating phase goes to metallic state at a gate
voltage of 2.6 V. However, the number of Raman modes do not change with
electrolyte gating showing that the metallic phase is still monoclinic. The
high frequency Raman mode A(7) near 616 cm ascribed to V-O vibration
of bond length 2.06 \AA~ in VO octahedra hardens with increasing gate
voltage and the B(3) mode near 654 cm softens. This shows that the
distortion of the VO octahedra in the monoclinic phase decreases with
gating. The time dependent Raman data at fixed gate voltages of 1 V (for 50
minute, showing enhancement of conductivity by a factor of 50) and 2 V (for 130
minute, showing further increase in conductivity by a factor of 5) show similar
changes in high frequency Raman modes A(7) and B(3) as observed in
gating. This slow change in conductance together with Raman frequency changes
show that the governing mechanism for metalization is more likely to the
diffusion controlled oxygen vacancy formation due to the applied electric
field.Comment: 5 pages, 6 figure
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