4,886 research outputs found
Human serum albumin crystals and method of preparation
Human serum albumin (HSA) crystals are provided in the form of tetragonal plates having the space groups P42(sub 1)2, the crystals being grown to sizes in excess of 0.5 mm in two dimensions and a thickness of 0.1 mm. Growth of the crystals is carried out by a hanging drop method wherein a precipitant solution containing polyethylene glycol (PEG) and a phosphate buffer is mixed with an HSA solution, and a droplet of mixed solution is suspended over a well of precipitant solution. Crystals grow to the desired size in 3 to 7 days. Concentration of reagents, pH and other parameters are controlled within prescribed limits. The resulting crystals exhibit a size and quality such as to allow performance of x ray diffraction studies and enable the conduct of drug binding studies as well as genetic engineering studies
'Now' with Subordinate Clauses
We investigate a novel use of the English temporal modifier ‘now’, in which it combines with a subordinate clause. We argue for a univocal treatment of the expression, on which the subordinating use is taken as basic and the non-subordinating uses are derived. We start by surveying central features of the latter uses which have been discussed in previous work, before introducing key observations regarding the subordinating use of ‘now’ and its relation to deictic and anaphoric uses. All of these data, it is argued, can be accounted for on our proposed analysis. We conclude by comparing ‘now’ to a range of other expressions which exhibit similar behavior
Graphene valley filter using a line defect
With its two degenerate valleys at the Fermi level, the band structure of
graphene provides the opportunity to develop unconventional electronic
applications. Herein, we show that electron and hole quasiparticles in graphene
can be filtered according to which valley they occupy without the need to
introduce confinement. The proposed valley filter is based on scattering off a
recently observed line defect in graphene. Quantum transport calculations show
that the line defect is semitransparent and that quasiparticles arriving at the
line defect with a high angle of incidence are transmitted with a valley
polarization near 100%.Comment: 5 pages, 4 figure
Valley and spin polarization from graphene line defect scattering
Quantum transport calculations describing electron scattering off an extended
line defect in graphene are presented. The calculations include potentials from
local magnetic moments recently predicted to exist on sites adjacent to the
line defect. The transmission probability is derived and expressed as a
function of valley, spin, and angle of incidence of an electron at the Fermi
level being scattered. It is shown that the previously predicted valley
polarization in a beam of transmitted electrons is not significantly influenced
by the presence of the magnetic moments. These moments, however, do introduce
some spin polarization, in addition to the valley polarization, albeit no more
than about 20%.Comment: 6 pages, 4 figure
Warped Functional Analysis of Variance
This article presents an Analysis of Variance model for functional data that
explicitly incorporates phase variability through a time-warping component,
allowing for a unified approach to estimation and inference in presence of
amplitude and time variability. The focus is on single-random-factor models but
the approach can be easily generalized to more complex ANOVA models. The
behavior of the estimators is studied by simulation, and an application to the
analysis of growth curves of flour beetles is presented. Although the model
assumes a smooth latent process behind the observed trajectories, smoothness of
the observed data is not required; the method can be applied to the sparsely
observed data that is often encountered in longitudinal studies
Protein crystal growth tray assembly
A protein crystal growth tray assembly includes a tray that has a plurality of individual crystal growth chambers. Each chamber has a movable pedestal which carries a protein crystal growth compartment at an upper end. The several pedestals for each tray assembly are ganged together for concurrent movement so that the solutions in the various pedestal growth compartments can be separated from the solutions in the tray's growth chambers until the experiment is to be activated
Apparatus for mixing solutions in low gravity environments
An apparatus is disclosed for allowing mixing of solutions in low gravity environments so as to carry out crystallization of proteins and other small molecules or other chemical syntheses, under conditions that maximize crystal growth and minimize disruptive turbulent effects. The apparatus is comprised of a housing, a plurality of chambers, and a cylindrical rotatable valve disposed between at least two of the chambers, said valve having an internal passageway so as to allow fluid movement between the chambers by rotation of the valve. In an alternate embodiment of the invention, a valve is provided having an additional internal passage way so that fluid from a third chamber can be mixed with the fluids of the first two chambers. This alternate embodiment of the invention is particularly desirable when it is necessary to provide a termination step to the crystal growth, or if a second synthetic step is required
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