Fluorine gas as a cleaning agent for Apollo bulk-sample containers

A technique has been developed for cleaning Apollo bulk sample containers using fluorine gas as the cleaning agent

Field-Induced Magnetic and Structural Domain Alignment in PrO2

We present a neutron diffraction study of the magnetic structure of single crystal PrO2 under applied fields of 0-6 T. As the field is increased, changes are observed in the magnetic Bragg intensities. These changes are found to be irreversible when the field is reduced, but the original intensities can be recovered by heating to T > 122 K, then re-cooling in zero field. The antiferromagnetic ordering temperature TN = 13.5 K and the magnetic periodicity are unaffected by the applied field. We also report measurements of the magnetic susceptibility of single crystal PrO2 under applied fields of 0-7 T. These show strong anisotropy, as well as an anomaly at T = 122 +/- 2 K which coincides with the temperature TD = 120 +/- 2 K at which a structural distortion occurs. For fields applied along the [100] direction the susceptibility increases irreversibly with field in the temperature range TN < T < TD. However, for fields along [110] the susceptibility is independent of field in this range. We propose structural domain alignment, which strongly influences the formation of magnetic domains below TN, as the mechanism behind these changes.Comment: 11 pages, 13 figures, 5 tables. Minor typographical changes in v

Cooperative Jahn-Teller Distortion in PrO2

We report neutron diffraction data on single crystal PrO2 which reveal a cooperative Jahn-Teller distortion at TD = 120 +/- 2 K. Below this temperature an internal distortion of the oxygen sublattice causes the unit cell of the crystallographic structure to become doubled along one crystal axis. We discuss several possible models for this structure. The antiferromagnetic structure below TN = 13.5 K is found to consist of two components, one of which shares the same doubled unit cell as the distorted crystallographic structure. We also present measurements of the magnetic susceptibility, the specific heat capacity and the electrical conductivity of PrO2. The susceptibility data show an anomaly at a temperature close to TD. From the specific heat capacity data we deduce that the ground state is doubly degenerate, consistent with a distortion of the cubic local symmetry. We discuss possible mechanisms for this. The conductivity shows an activated behaviour with an activation energy Ea = 0.262 +/- 0.003 eV.Comment: 12 pages, 14 figures, 2 tables. Additional suggested structure in v

Acceptability of the female condom in different groups of women in South Africa - A multicentred study to inform the national female condom introductory strategy

Objectives. To assess the acceptability of the female condom to different groups of women and their partners in South Africa. Design. Descriptive, cross-sectional study. Setting. Multicentre study conducted in five sites. Subjects. The study recruited 678 women from five centres-to an acceptability trial of the female condom. Acceptability and successful use varied between the centres. Outcome measures. Factors affecting successful use and willingness and intention to use the method again. Results. In total, 209 women used the condom at least once. Discontinuation rates were high, with partner reluctance to try the method as the main reason given for discontinuation at all sites. Women who had previous experience with the male condom or who received a more intensive training session generally found the device easier to use. The main issues concerning women were over-lubrication (27%) and concern that the device was too large (28%). The majority of women said that they would be interested in using the method again (86%) and would recommend it to friends (95%). Conclusions. Overcoming partner opposition is an important issue to address when introducing the method. The study was used to address the national introductory strategy of the female condom, which began in 1998

Sub-micron, Metal Gate, High-к Dielectric, Implant-free, Enhancement-mode III-V MOSFETs

The performance of 300nm, 500nm and 1μm metal gate, implant free, enhancement mode III-V MOSFETs are reported. Devices are realised using a 10nm MBE grown Ga2O3/(GaxGd1-x)2O3 high-κ (κ=20) dielectric stack grown upon a δ-doped AlGaAs/InGaAs/AlGaAs/GaAs heterostructure. Enhancement mode operation is maintained across the three reported gate lengths with a reduction in threshold voltage from 0.26 V to 0.08 V as the gate dimension is reduced from 1 μm to 300 nm. An increase in transconductance is also observed with reduced gate dimension. Maximum drain current of 420 μA/μm and extrinsic transconductance of 400 µS/µm are obtained from these devices. Gate leakage current of less than 100pA and subthreshold slope of 90 mV/decade were obtained for all gate lengths. These are believed to be the highest performance submicron enhancement mode III-V MOSFETs reported to date

Acceptability of the female condom in different groups Of women in South Africa-A Multicentred study to inform the national female condom introductory strategy

Objectives. To assess the acceptability of the female condom to different groups of women and their partners in South Africa.Design. Descriptive, cross-sectional study.Setting. Multicentre study conducted in five sites.Subjects. The study recruited 678 women from five centres to an acceptability trial of the female condom. Acceptability and successful use varied between the centres. Outcome measures. Factors affecting successful use and willingness and intention to use the method again.Results. In total, 209 women used the condom at least once. Discontinuation rates were high, with partner reluctance to try the method as the main reason given for discontinuation at all sites. Women who had previous experience with the male condom or who received a more intensive training session generally found the device easier to use. The main issues concerning women were over-lubrication (27%) and concern that the device was too large (28%). The majority of women said that they would be interested in using the method again (86%) and would recommend it to friends (95%).Conclusions. Overcoming partner opposition is an important issue to address when introducing the method. The study was used to address the national introductory strategy of the female condom, which began in 1998

Electron mobility in surface- and buried- channel flatband In_0.53Ga_0.47As MOSFETs with ALD Al₂O₃ gate dielectric.

In this paper, we investigate the scaling potential of flatband III-V MOSFETs by comparing the mobility of surface and buried In&lt;sub&gt;0.53&lt;/sub&gt;Ga&lt;sub&gt;0.47&lt;/sub&gt;As channel devices employing an Atomic Layer Deposited (ALD) Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; gate dielectric and a delta-doped InGaAs/InAlAs/InP heterostructure. Peak electron mobilities of 4300 cm&lt;sup&gt;2&lt;/sup&gt;/V·s and 6600 cm&lt;sup&gt;2&lt;/sup&gt;/V·s at a carrier density of 3×1012 cm&lt;sup&gt;-2&lt;/sup&gt; for the surface and buried channel structures respectively were determined. In contrast to similarly scaled inversion-channel devices, we find that mobility in surface channel flatband structures does not drop rapidly with electron density, but rather high mobility is maintained up to carrier concentrations around 4x10&lt;sup&gt;12&lt;/sup&gt; cm&lt;sup&gt;-2&lt;/sup&gt; before slowly dropping to around 2000 cm&lt;sup&gt;2&lt;/sup&gt;/V·s at 1x10M&lt;sup&gt;13&lt;/sup&gt; cm&lt;sup&gt;-2&lt;/sup&gt;. We believe these to be world leading metrics for this material system and an important development in informing the III-V MOSFET device architecture selection process for future low power, highly scaled CM