1,234 research outputs found
Automated operation of a home made torque magnetometer using LabVIEW
In order to simplify and optimize the operation of our home made torque
magnetometer we created a new software system. The architecture is based on
parallel, independently running instrument handlers communicating with a main
control program. All programs are designed as command driven state machines
which greatly simplifies their maintenance and expansion. Moreover, as the main
program may receive commands not only from the user interface, but also from
other parallel running programs, an easy way of automation is achieved. A
program working through a text file containing a sequence of commands and
sending them to the main program suffices to automatically have the system
conduct a complex set of measurements. In this paper we describe the system's
architecture and its implementation in LabVIEW.Comment: 6 pages, 7 figures, submitted to Rev. Sci. Inst
Nuclear Magnetic Resonance and Hyperfine Structure
Contains research objectives and reports on one research project
Nuclear Magnetic Resonance and Hyperfine Structure
Contains research objectives and reports on two research projects
Injection into Supersonic Boundary Layers
A method for injection of gas into the boundary layer on a slender body in supersonic flow while minimizing perturbation to the mean flow is examined. Injection of gas is equivalent to a sudden increase in the displacement thickness of the boundary layer, which produces an oblique shock that propagates into the inviscid region of the flow. It is found that modification of the geometry of the body can compensate for the increased displacement thickness created by injection and minimize the production of oblique waves. However, the resulting near-wall injection layer is observed to be unstable and a turbulent boundary layer develops downstream of the injection region. The instability of the flow is examined experimentally using high-speed schlieren visualization and numerically using linear stability analysis of velocity profiles from a compressible Navier–Stokes computation. At the present postshock Mach number of about 3.8, both first- and second-mode instabilities are active, though computations predict that the first mode is primarily responsible for transition downstream of the injector
Coherent Ro-vibrational Revivals in a Thermal Molecular Ensemble
We report an experimental and theoretical study of the evolution of
vibrational coherence in a thermal ensemble of nitrogen molecules. Rotational
dephasing and rephasing of the vibrational coherence is detected by coherent
anti-Stokes Raman scattering. The existence of ro-vibrational coupling and the
discrete energy spectrum of the rotational bath lead to a whole new class of
full and fractional ro-vibrational revivals. Following the rich ro-vibrational
dynamics on a nanosecond time scale with sub-picosecond time resolution enables
us to determine the second-order ro-vibrational constant and assess
new possibilities of controlling decoherence.Comment: submitted at Physical Review
Digestibility of resistant starch type 3 is affected by crystal type, molecular weight and molecular weight distribution
Resistant starch type 3 (RS-3) holds great potential as a prebiotic by supporting gut microbiota following intestinal digestion. However the factors influencing the digestibility of RS-3 are largely unknown. This research aims to reveal how crystal type and molecular weight (distribution) of RS-3 influence its resistance. Narrow and polydisperse α-glucans of degree of polymerization (DP) 14–76, either obtained by enzymatic synthesis or debranching amylopectins from different sources, were crystallized in 12 different A- or B-type crystals and in vitro digested. Crystal type had the largest influence on resistance to digestion (A >>> B), followed by molecular weight (Mw) (high DP >> low DP) and Mw distribution (narrow disperse > polydisperse). B-type crystals escaping digestion changed in Mw and Mw distribution compared to that in the original B-type crystals, whereas A-type crystals were unchanged. This indicates that pancreatic α-amylase binds and acts differently to A- or B-type RS-3 crystals.</p
Magnet Laboratory Research
Contains research objectives and reports on three research projects
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