4,458 research outputs found
Accelerated battery-life testing - A concept
Test program, employing empirical, statistical and physical methods, determines service life and failure probabilities of electrochemical cells and batteries, and is applicable to testing mechanical, electrical, and chemical devices. Data obtained aids long-term performance prediction of battery or cell
The effect of low-energy ion-implantation on the electrical transport properties of Si-SiO2 MOSFETs
Using silicon MOSFETs with thin (5nm) thermally grown SiO2 gate dielectrics,
we characterize the density of electrically active traps at low-temperature
after 16keV phosphorus ion-implantation through the oxide. We find that, after
rapid thermal annealing at 1000oC for 5 seconds, each implanted P ion
contributes an additional 0.08 plus/minus 0.03 electrically active traps,
whilst no increase in the number of traps is seen for comparable silicon
implants. This result shows that the additional traps are ionized P donors, and
not damage due to the implantation process. We also find, using the room
temperature threshold voltage shift, that the electrical activation of donors
at an implant density of 2x10^12 cm^-2 is ~100%.Comment: 11 pages, 10 figure
A study of the magnesium content of plant material
The experiments with grass and clover at Boghall and
ryegrass at Bush showed that: -1. the mineral content of different species of grass and
clover varied considerably, the clovers tending to be higher
in mineral content than the grasses.2. the mineral content of white clover was affected by the
grass with which it was grown and the competition with the
grass for the available nutrients, particularly in the case
of phosphorus.3. the mineral content of both grasses and clover varied
considerably from month to month, the nature of the variation
depending on the frequency of cutting. In grasses cut
monthly, the minerai content tended to increase towards the
end of the season, while in uncut ryegrass, the mineral
content decreased as the grass matured.4. treatment with "nitrochalk" increased the calcium and
magnesium contents of grasses throughout the season, and
increased the phosphorus content initially. The effect of
treatment on the clover seemed to depend on the yield and
leafiness of the grass with which it was grown and the
consequent competition between the grass and clover.5. treatment with heavy dressings of MgSO4.7H2O increased
he magnesium content of ryegrass throughout the season.
. the uptake of minerals varied from species to species
and from month to month throughout the season, the monthly
variation generally following that of the yield. The uptake
of minerals by clover was lower than that of the grasses
/because of the lower yield of the clover. The total seasonal
uptakes of calcium and of phosphorus were greater than the
uptake of magnesium.7. treatment with "nitrochalk" increased the uptake of all
three elements by both grass and clover.The mineral content of a sward will therefore depend on
the botanical composition of the sward, the frequency of
cutting, the time of year and tiffe fertiliser treatment.
The experiments with mixed herbage grown for hay and for
dried grass bore out these results and showed that: -1. the magnesium content of the herbage depended on the
available magnesium in the soil.2. the mineral content of herbage decreased with advancing
maturity.3. the effect of the fertilisers studied depended not only
on the nature of the fertiliser but also on the mineral status
of the soil to which it was applied and the existing cation:
anion ratios.(a) magnesium sulphate raised the magnesium content of
the herbage, particularly where the soil was low in available
magnesium.(b) potassium sulphate depressed the magnesium and
phsophorus contents of herbage and in some cases the calcium
content also.(c) potassium -magnesium sulphate had little effect on
the magnesium ani phosphorus contents of herbage, and was
therefore more suitable for use where the soil was low in
available magnesium.The experiments with turnips and kale showed that: -
1. the yield of dry matter and the uptake of minerals in
the leaf was less than that of the roots in turnips and of
the stem in kale.
2. the mineral content of the leaf was higher than that of
the roots in turnips and of the stem in kale.
3. the magnesium content of turnip leaves depended on the
available magnesium in the soil.
4. treatment with potassium -magnesium sulphate increased
¡the dry matter yield of turnip roots where the available
soil magnesium was low, and increased the yield of magnesium
content of kale leaves, and the uptake of magnesium by the
leaves
Differential thermal analysis and solution growth of intermetallic compounds
To obtain single crystals by solution growth, an exposed primary
solidification surface in the appropriate, but often unknown, equilibrium alloy
phase diagram is required. Furthermore, an appropriate crucible material is
needed, necessary to hold the molten alloy during growth, without being
attacked by it. Recently, we have used the comparison of realistic simulations
with experimental differential thermal analysis (DTA) curves to address both
these problems. We have found: 1) complex DTA curves can be interpreted to
determine an appropriate heat treatment and starting composition for solution
growth, without having to determine the underlying phase diagrams in detail. 2)
DTA can facilitate identification of appropriate crucible materials. DTA can
thus be used to make the procedure to obtain single crystals of a desired phase
by solution growth more efficient. We will use some of the systems for which we
have recently obtained single-crystalline samples using the combination of DTA
and solution growth as examples. These systems are TbAl, PrNiSi,
and YMnAl.Comment: 17 pages, 8 figure
Electrically-detected magnetic resonance in ion-implanted Si:P nanostructures
We present the results of electrically-detected magnetic resonance (EDMR)
experiments on silicon with ion-implanted phosphorus nanostructures, performed
at 5 K. The devices consist of high-dose implanted metallic leads with a square
gap, into which Phosphorus is implanted at a non-metallic dose corresponding to
10^17 cm^-3. By restricting this secondary implant to a 100 nm x 100 nm region,
the EDMR signal from less than 100 donors is detected. This technique provides
a pathway to the study of single donor spins in semiconductors, which is
relevant to a number of proposals for quantum information processing.Comment: 9 pages, 3 figure
Language and art activities at primary level: the EE dimension
The inter-relationship of language and art with environmental education (EE) within the Primary Education Upgrading Prograrnne (PEUP) in Bophuthatswana is described and discussed
Diagnosing pregnancy in sheep : the \u27Scanopreg\u27
The Scanopreg , an ultrasonic machine for diagnosing pregnancy in sheep, is effective as early as eight to nine weeks of pregnancy, and could therefore be a useful management tool
Low-Temperature Rapid Synthesis and Superconductivity of Fe-Based Oxypnictide Superconductors
we were able to develop a novel method to synthesize Fe-based oxypnictide
superconductors. By using LnAs and FeO as the starting materials and a
ball-milling process prior to solid-state sintering, Tc as high as 50.7 K was
obtained with the sample of Sm 0.85Nd0.15FeAsO0.85F0.15 prepared by sintering
at temperatures as low as 1173 K for times as short as 20 min.Comment: 2 pages,2 figures, 1 tabl
Carbide/nitride grain refined rare earth-iron-boron permanent magnet and method of making
A method of making a permanent magnet wherein 1) a melt is formed having a base alloy composition comprising RE, Fe and/or Co, and B (where RE is one or more rare earth elements) and 2) TR (where TR is a transition metal selected from at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Al) and at least one of C and N are provided in the base alloy composition melt in substantially stoichiometric amounts to form a thermodynamically stable compound (e.g. TR carbide, nitride or carbonitride). The melt is rapidly solidified in a manner to form particulates having a substantially amorphous (metallic glass) structure and a dispersion of primary TRC, TRN and/or TRC/N precipitates. The amorphous particulates are heated above the crystallization temperature of the base alloy composition to nucleate and grow a hard magnetic phase to an optimum grain size and to form secondary TRC, TRN and/or TRC/N precipitates dispersed at grain boundaries. The crystallized particulates are consolidated at an elevated temperature to form a shape. During elevated temperature consolidation, the primary and secondary precipitates act to pin the grain boundaries and minimize deleterious grain growth that is harmful to magnetic properties
- …