4,839,079 research outputs found
Nanostructured Chitosan-Based Biomaterials for Sustained and Colon-Specific Resveratrol Release
In the present work, we demonstrate the preparation of chitosan-based composites as vehicles of the natural occurring multi-drug resveratrol (RES). Such systems are endowed with potential therapeutic effects on inflammatory bowel diseases (IBD), such as Crohn’s disease (CD) and ulcerative colitis, through the sustained colonic release of RES from long-lasting mucoadhesive drug depots. The loading of RES into nanoparticles (NPs) was optimized regarding two independent variables: RES/polymer ratio, and temperature. Twenty experiments were carried out and a Box–Behnken experimental design was used to evaluate the significance of these independent variables related to encapsulation efficiency (EE). The enhanced RES EE values were achieved in 24 h at 39 °C and at RES/polymer ratio of 0.75:1 w/w. Sizes and polydispersities of the optimized NPs were studied by dynamic light scattering (DLS). Chitosan (CTS) dispersions containing the RES-loaded NPs were ionically gelled with tricarballylic acid to yield CTS-NPs composites. Macro- and microscopic features (morphology and porosity studied by SEM and spreadability), thermal stability (studied by TGA), and release kinetics of the RES-loaded CTS-NPs were investigated. Release patterns in simulated colon conditions for 48 h displayed significant differences between the NPs (final cumulative drug release: 79–81%), and the CTS-NPs composites (29–34%)
Small NFAs from Regular Expressions: Some Experimental Results
Regular expressions (res), because of their succinctness and clear syntax,
are the common choice to represent regular languages. However, efficient
pattern matching or word recognition depend on the size of the equivalent
nondeterministic finite automata (NFA). We present the implementation of
several algorithms for constructing small epsilon-free NFAss from res within
the FAdo system, and a comparison of regular expression measures and NFA sizes
based on experimental results obtained from uniform random generated res. For
this analysis, nonredundant res and reduced res in star normal form were
considered.Comment: Proceedings of 6th Conference on Computability in Europe (CIE 2010),
pages 194-203, Ponta Delgada, Azores, Portugal, June/July 201
Strain engineering and photocatalytic application of single-layer ReS
We present a theoretical study on the electronic, dynamical, and
photocatalytic properties of single-layer ReS under uniaxial and shear
strains. The single-layer ReS shows strong anisotropic responses to
straining. It remains dynamically stable for a wide range of -axial strain,
but becomes unstable for 2\% -axial compressive strain. The single-layer
ReS is calculated to be an indirect bandgap semiconductor, and there is an
indirectdirect bandgap transition under 15\% -axial tensile straining.
The single-layer ReS is predicted incapable of catalyzing the water
oxidation reaction. However, 15\% -axial tensile strain can enable the
single-layer ReS for overall photocatalytic water splitting. Besides, the
single-layer ReS can also catalyze the overall water splitting and be most
efficient under acidic water solutions with pH=3.8
Direct observation of the band gap transition in atomically thin ReS
ReS is considered as a promising candidate for novel electronic and
sensor applications. The low crystal symmetry of the van der Waals compound
ReS leads to a highly anisotropic optical, vibrational, and transport
behavior. However, the details of the electronic band structure of this
fascinating material are still largely unexplored. We present a
momentum-resolved study of the electronic structure of monolayer, bilayer, and
bulk ReS using k-space photoemission microscopy in combination with
first-principles calculations. We demonstrate that the valence electrons in
bulk ReS are - contrary to assumptions in recent literature - significantly
delocalized across the van der Waals gap. Furthermore, we directly observe the
evolution of the valence band dispersion as a function of the number of layers,
revealing a significantly increased effective electron mass in single-layer
crystals. We also find that only bilayer ReS has a direct band gap. Our
results establish bilayer ReS as a advantageous building block for
two-dimensional devices and van der Waals heterostructures
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