Search results for "530"
showing 10 items of 1476 documents
Toward fast malaria detection by secondary speckle sensing microscopy
2012
Diagnosis of malaria must be rapid, accurate, simple to use, portable and low cost, as suggested by the World Health Organization (WHO). Despite recent efforts, the gold standard remains the light microscopy of a stained blood film. This method can detect low parasitemia and identify different species of Plasmodium. However, it is time consuming, it requires well trained microscopist and good instrumentation to minimize misinterpretation, thus the costs are considerable. Moreover, the equipment cannot be easily transported and installed. In this paper we propose a new technique named "secondary speckle sensing microscopy" ((SM)-M-3) based upon extraction of correlation based statistics of s…
Movilidad humana: una revisión teórica aplicable de los flujos migratorios en España
2020
El texto tiene el objetivo de realizar una revisión teórica aplicable entorno a las migraciones en el contexto particular español. Se ha realizado una revisión bibliográfica aplicable disponible en torno al tema, con el fin de ofrecer una recopilación y selección de la información disponible a este respecto partiendo de la dicotomía que haría en su momento López de Lera (1995), los que “vienen a descansar y los que vienen a trabajar”. Es importante porque el desarrollo teórico de sendas perspectivas de la migración es divergente. Este es el aporte del texto, realizar un recorrido por los dos caminos migratorios y delimitar las principales corrientes.
Changes in the hydrogen-bonding strength of internal water molecules and cysteine residues in the conductive state of channelrhodopsin-1
2014
Water plays an essential role in the structure and function of proteins, particularly in the less understood class of membrane proteins. As the first of its kind, channelrhodopsin is a light-gated cation channel and paved the way for the new and vibrant field of optogenetics, where nerve cells are activated by light. Still, the molecular mechanism of channelrhodopsin is not understood. Here, we applied time-resolved FT-IR difference spectroscopy to channelrhodopsin-1 from Chlamydomonas augustae. It is shown that the (conductive) P2(380) intermediate decays with τ ≈ 40 ms and 200 ms after pulsed excitation. The vibrational changes between the closed and the conductive states were analyzed in…
Tuning molecular self-assembly on bulk insulator surfaces by anchoring of the organic building blocks.
2013
Molecular self-assembly constitutes a versatile strategy for creating functional structures on surfaces. Tuning the subtle balance between intermolecular and molecule-surface interactions allows structure formation to be tailored at the single-molecule level. While metal surfaces usually exhibit interaction strengths in an energy range that favors molecular self-assembly, dielectric surfaces having low surface energies often lack sufficient interactions with adsorbed molecules. As a consequence, application-relevant, bulk insulating materials pose significant challenges when considering them as supporting substrates for molecular self-assembly. Here, the current status of molecular self-ass…
Effects of confinement and external fields on structure and transport in colloidal dispersions in reduced dimensionality
2012
In this work, we focus on low-dimensional colloidal model systems, via simulation studies and also some complementary experiments, in order to elucidate the interplay between phase behavior, geometric structures and transport properties. In particular, we try to investigate the (nonlinear!) response of these very soft colloidal systems to various perturbations: uniform and uniaxial pressure, laser fields, shear due to moving boundaries and randomly quenched disorder.We study ordering phenomena on surfaces or in monolayers by Monte Carlo computer simulations of binary hard-disk mixtures, the influence of a substrate being modeled by an external potential. Weak external fields allow a control…
Kinetics of proton release and uptake by channelrhodopsin-2
2012
Electrophysiological experiments showed that the light-activated cation channel channelrhodopsin-2 (ChR2) pumps protons in the absence of a membrane potential. We determined here the kinetics of transient pH change using a water-soluble pH-indicator. It is shown that ChR2 released protons prior to uptake with a stoichiometry of 0.3 protons per ChR2. Comparison to the photocycle kinetics revealed that proton release and uptake match rise and decay of the View the MathML sourceP3520 intermediate. As the View the MathML sourceP3520 state also represents the conductive state of cation channeling, the concurrence of proton pumping and channel gating implies an intimate mechanistic link of the tw…
Local structure and dynamics of wurtzite‐type ZnO from simulation‐based EXAFS analysis
2014
Conventional methods of EXAFS data analysis are often limited to the nearest coordination shells of the absorbing atom due to the difficulties in accurate accounting for the so-called multiple-scattering effects. Besides, it is often difficult to resolve the non-equivalent groups of atoms in a single coordination shell due to strong correlation between structural parameters. In this study we overcome these problems by applying two different simulation-based methods, i.e., classical molecular dynamics (MD) and reverse Monte with evolutionary algorithm (EA), to the analysis of the Zn K-edge EXAFS data for wurtzite-type bulk ZnO. The RMC/EA-EXAFS method allowed us to separate the contributions…
Electroburning of few-layer graphene flakes, epitaxial graphene, and turbostratic graphene discs in air and under vacuum
2015
Graphene-based electrodes are very promising for molecular electronics and spintronics. Here we report a systematic characterization of the electroburning (EB) process, leading to the formation of nanometer-spaced gaps, on different types of few-layer graphene (namely mechanically exfoliated graphene on SiO2, graphene epitaxially grown on the C-face of SiC and turbostratic graphene discs deposited on SiO2) under air and vacuum conditions. The EB process is found to depend on both the graphene type and on the ambient conditions. For the mechanically exfoliated graphene, performing EB under vacuum leads to a higher yield of nanometer-gap formation than working in air. Conversely, for graphene…
Reversible and Efficient Light-Induced Molecular Switching on an Insulator Surface
2018
Prototypical molecular switches such as azobenzenes exhibit two states, i.e., trans and cis, with different characteristic physical properties. In recent years various derivatives were investigated on metallic surfaces. However, bulk insulators as supporting substrate reveal important advantages since they allow electronic decoupling from the environment, which is key to control the switching properties. Here, we report on the light-induced isomerization of an azobenzene derivative on a bulk insulator surface, in this case calcite (101̅4), studied by atomic force microscopy with submolecular resolution. Surprisingly, cis isomers appear on the surface already directly after preparation, indi…
Influence of Laccase and Tyrosinase on the Antioxidant Capacity of Selected Phenolic Compounds on Human Cell Lines
2015
Polyphenolic compounds affect the color, odor and taste of numerous food products of plant origin. In addition to the visual and gustatory properties, they serve as radical scavengers and have antioxidant effects. Polyphenols, especially resveratrol in red wine, have gained increasing scientific and public interest due to their presumptive beneficial impact on human health. Enzymatic oxidation of phenolic compounds takes place under the influence of polyphenol oxidases (PPO), including tyrosinase and laccase. Several studies have demonstrated the radical scavenger effect of plants, food products and individual polyphenols in vitro, but, apart from resveratrol, such impact has not been prove…