8,233 research outputs found
Experiments with Corn.
Cooperative Tests of Varieties -- Variety Tests on the Experiment Station Farm -- Relation of Size of Ear to Yield -- Thickness of Planting Corn -- Tillering of Corn -- Increasing Yields of Corn by Selection of Plants -- Selecting Corn for High Oil Content -- Adaptation of Corn to a New Locality -- A Cross-Bred Variety -- Keeping Seed Corn -- Depth of Planting
Experiments with Corn.
Cooperative Tests of Varieties -- Variety Tests on the Experiment Station Farm -- Relation of Size of Ear to Yield -- Thickness of Planting Corn -- Tillering of Corn -- Increasing Yields of Corn by Selection of Plants -- Selecting Corn for High Oil Content -- Adaptation of Corn to a New Locality -- A Cross-Bred Variety -- Keeping Seed Corn -- Depth of Planting
Winter Wheat: Cooperative Experiments with the United States Department of Agriculture
Variety Tests of Winter Wheat in 1902, 1903, and 1904 -- Cooperative Tests of Knarkof and Beloglina Wheats -- Nature and Causes of Yellow Berry in Hard Winter Wheat -- Running Out of Seed Wheat -- Importance of Good Tillage -- Variations in Wheat from Different Regions and in Different Season
A New Method for Searching for Free Fractional Charge Particles in Bulk Matter
We present a new experimental method for searching for free fractional charge
in bulk matter; this new method derives from the traditional Millikan liquid
drop method, but allows the use of much larger drops, 20 to 100 mm in diameter,
compared to the traditional method that uses drops less than 15 mm in diameter.
These larger drops provide the substantial advantage that it is then much
easier to consistently generate drops containing liquid suspensions of powdered
meteorites and other special minerals. These materials are of great importance
in bulk searches for fractional charge particles that may have been produced in
the early universe.Comment: 17 pages, 5 figures in a singl PDF file (created from WORD Doc.).
Submitted to Review of Scientific Instrument
Fluorescent Silicon Clusters and Nanoparticles
The fluorescence of silicon clusters is reviewed. Atomic clusters of silicon
have been at the focus of research for several decades because of the relevance
of size effects for material properties, the importance of silicon in
electronics and the potential applications in bio-medicine. To date numerous
examples of nanostructured forms of fluorescent silicon have been reported.
This article introduces the principles and underlying concepts relevant for
fluorescence of nanostructured silicon such as excitation, energy relaxation,
radiative and non-radiative decay pathways and surface passivation.
Experimental methods for the production of silicon clusters are presented. The
geometric and electronic properties are reviewed and the implications for the
ability to emit fluorescence are discussed. Free and pure silicon clusters
produced in molecular beams appear to have properties that are unfavourable for
light emission. However, when passivated or embedded in a suitable host, they
may emit fluorescence. The current available data show that both quantum
confinement and localised transitions, often at the surface, are responsible
for fluorescence. By building silicon clusters atom by atom, and by embedding
them in shells atom by atom, new insights into the microscopic origins of
fluorescence from nanoscale silicon can be expected.Comment: 5 figures, chapter in "Silicon Nanomaterials Sourcebook", editor
Klaus D. Sattler, CRC Press, August 201
Time-resolved impulse response of the magnetoplasmon resonance in a two-dimensional electron gas
We have used optically excited ultrashort electrical pulses to measure the
magnetoplasmon resonance of a two-dimensional electron gas formed in an
AlGaAs/GaAs heterostructure at frequencies up to 200 gigahertz. This is
accomplished by incorporating the sample into a guided wave probe operating in
a pumped (^{3}He) system. We are able to detect the resonance by launching a
stimulus pulse in the guide, and monitoring the system response in a time
resolved pump-probe arrangement. Data obtained from measurements yield resonant
frequencies that agree with the magnetoplasmon dispersion relation.Comment: 4 pages, 4 figure
Electrical activation and electron spin resonance measurements of implanted bismuth in isotopically enriched silicon-28
We have performed continuous wave and pulsed electron spin resonance
measurements of implanted bismuth donors in isotopically enriched silicon-28.
Donors are electrically activated via thermal annealing with minimal diffusion.
Damage from bismuth ion implantation is repaired during thermal annealing as
evidenced by narrow spin resonance linewidths (B_pp=12uT and long spin
coherence times T_2=0.7ms, at temperature T=8K). The results qualify ion
implanted bismuth as a promising candidate for spin qubit integration in
silicon.Comment: 4 pages, 4 figure
Stark shift and field ionization of arsenic donors in Si-SOI structures
We develop an efficient back gate for silicon-on-insulator (SOI) devices
operating at cryogenic temperatures, and measure the quadratic hyperfine Stark
shift parameter of arsenic donors in isotopically purified Si-SOI layers
using such structures. The back gate is implemented using MeV ion implantation
through the SOI layer forming a metallic electrode in the handle wafer,
enabling large and uniform electric fields up to 2 V/m to be
applied across the SOI layer. Utilizing this structure we measure the Stark
shift parameters of arsenic donors embedded in the Si SOI layer and find
a contact hyperfine Stark parameter of m/V. We also demonstrate electric-field driven dopant ionization in
the SOI device layer, measured by electron spin resonance.Comment: 5 pages, 3 figure
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