3,675 research outputs found
Results to be expected from light scattering dust analyzer during a rendezvous mission
The light scattering principle for particle detection is customary for the measurement of aerosols. Light scattering techniques can be applied to mixtures of particles (nephelometers) and to single particles as well. Measuring particle mixtures simplify detection because of the higher intensity level, however, information concerning the individual particle is lost. To provide well defined conditions over the whole rendezvous period, i.e., constant illumination beam and unchangeable scattering angle, the use of an artificial light source (instead of the sun) and a scattering volume located within the S/C is desirable. Considering this and the relatively low particle densities to be expected, the measurement of particle mixtures must be excluded
Supramolecular modification of ABC triblock terpolymers in confinement assembly
The self-assembly of AB diblock copolymers in three-dimensional (3D) soft confinement of nanoemulsions has recently become an attractive bottom up route to prepare colloids with controlled inner morphologies. In that regard, ABC triblock terpolymers show a more complex morphological behavior and could thus give access to extensive libraries of multicompartment microparticles. However, knowledge about their self-assembly in confinement is very limited thus far. Here, we investigated the confinement assembly of polystyrene-block-poly(4-vinylpyridine)-block-poly(tert-butyl methacrylate) (PS-b-P4VP-b-PT or SVT) triblock terpolymers in nanoemulsion droplets. Depending on the block weight fractions, we found spherical microparticles with concentric lamella–sphere (ls) morphology, i.e., PS/PT lamella intercalated with P4VP spheres, or unusual conic microparticles with concentric lamella–cylinder (lc) morphology. We further described how these morphologies can be modified through supramolecular additives, such as hydrogen bond (HB) and halogen bond (XB) donors. We bound donors to the 4VP units and analyzed changes in the morphology depending on the binding strength and the length of the alkyl tail. The interaction with the weaker donors resulted in an increase in volume of the P4VP domains, which depends upon the molar fraction of the added donor. For donors with a high tendency of intermolecular packing, a visible change in the morphology was observed. This ultimately caused a shape change in the microparticle. Knowledge about how to control inner morphologies of multicompartment microparticles could lead to novel carbon supports for catalysis, nanoparticles with unprecedented topologies, and potentially, reversible shape changes by light actuation
On the formation fo caldera-like features on Ganymede: implicatoins from Galileo-G28 images
Topographic data are used to find implications for the formation of Caldera-like Features on Ganymede
Peptide Retention in Hydrophilic Strong Anion Exchange Chromatography Is Driven by Charged and Aromatic Residues
Hydrophilic
strong anion exchange chromatography (hSAX) is becoming
a popular method for the prefractionation of proteomic samples. However,
the use and further development of this approach is affected by the
limited understanding of its retention mechanism and the absence of
elution time prediction. Using a set of 59 297 confidentially
identified peptides, we performed an explorative analysis and built
a predictive deep learning model. As expected, charged residues are
the major contributors to the retention time through electrostatic
interactions. Aspartic acid and glutamic acid have a strong retaining
effect and lysine and arginine have a strong repulsion effect. In
addition, we also find the involvement of aromatic amino acids. This
suggests a substantial contribution of cation−π interactions
to the retention mechanism. The deep learning approach was validated
using 5-fold cross-validation (CV) yielding a mean prediction accuracy
of 70% during CV and 68% on a hold-out validation set. The results
of this study emphasize that not only electrostatic interactions but
rather diverse types of interactions must be integrated to build a
reliable hSAX retention time predictor
Cooling dynamics of a dilute gas of inelastic rods: a many particle simulation
We present results of simulations for a dilute gas of inelastically colliding
particles. Collisions are modelled as a stochastic process, which on average
decreases the translational energy (cooling), but allows for fluctuations in
the transfer of energy to internal vibrations. We show that these fluctuations
are strong enough to suppress inelastic collapse. This allows us to study large
systems for long times in the truely inelastic regime. During the cooling stage
we observe complex cluster dynamics, as large clusters of particles form,
collide and merge or dissolve. Typical clusters are found to survive long
enough to establish local equilibrium within a cluster, but not among different
clusters. We extend the model to include net dissipation of energy by damping
of the internal vibrations. Inelatic collapse is avoided also in this case but
in contrast to the conservative system the translational energy decays
according to the mean field scaling law, E(t)\propto t^{-2}, for asymptotically
long times.Comment: 10 pages, 12 figures, Latex; extended discussion, accepted for
publication in Phys. Rev.
Is the seventh district's economy deindustrializing?
Federal Reserve District, 7th ; Industries - North Central states ; Manufactures - North Central states
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