Incipient motion of a single particle on regular substrates in laminar shear flow

We study experimentally the critical conditions for incipient motion of a single spherical particle deposited on a regular substrate under laminar flow conditions. The substrates are triangular and quadratic arrangements of identical glass spheres. For the latter configuration, the distance between the substrate spheres is varied, resulting in different partial shielding of the deposited particle to the shear flow. For the studied particle Reynolds numbers range between 3 × 10−4 and 3, the critical Shields number is independent from the particle density and from the particle Reynolds number but it depends significantly on the geometry of the substrate. Depending on the spacing between the substrate beads and thus on the exposure of the particle to the flow, we have observed an increase of about 50 percent in the critical Shields number. Studying the onset of particle motion as a function of the orientation of the substrate to the flow direction we find that the critical Shields number changes by up to a factor of 2, which is mainly due to the fact that the particle travels through the troughs of the substrate and hence the shear force in travel direction diminishes if not in line with the flow direction. Besides the critical Shields number we study the initial stage of particle motion by detecting the minimum time that is necessary for maintaining a certain Shields number to change the position of a single particle on the regular substrates. In the range studied, the initial stage of motion on the scale of the substrate's periodicity is mainly governed by the equilibrium particle motion

Easy and versatile coating approach for long-living white hybrid light-emitting diodes

Herein, we provide a new easy-to-do protocol for preparing luminescent rubber-like materials based on a wide palette of compounds, such as small-molecules, quantum dots, polymers, and coordination complexes. The combination of this new protocol with that for preparing similar rubbers based on fluorescent proteins states the universal character of our approach. This is further assessed by using comprehensive spectroscopic and rheological investigations. Furthermore, the novel luminescent rubbers are applied as down-converting packing systems to develop white hybrid light-emitting diodes (WHLEDs), which are heralded as a solid alternative to achieve energy-saving, solid-state, and white-emitting sources in the coming future. As such, the current work also provides a clear prospect of this emerging lighting technology by means of a direct comparison among WHLEDs fabricated with all the above-mentioned down-converting systems. Here, the use of rubbers based on coordination complexes outperforms the others in terms of both luminous efficiency and colour quality with an unprecedented stability superior to 1000 h under continuous operation conditions. This represents an order of magnitude enhancement compared to the state-of-the-art WHLEDs, while keeping luminous efficiencies of around 100 lm W−1

How do neighbors affect incipient particle motion in laminar shear flow?

We experimentally study how neighboring particles affect the incipient motion of particles on regular substrates and exposed to a laminar shear flow. To this end, we determine the critical Shields number and determine whether the particle rolls or slides. The substrates consist of a monolayer of fixed spheres of uniform size that are regularly arranged in triangular and quadratic configurations. Neighboring particles influence the incipient motion by shielding to the shear flow and may inhibit continuous motion once they are in direct contact with the particle. At the low particle Reynolds numbers studied, neighboring spheres on the monolayer only affect the incipient particle motion if they are closer than about 3 particle diameters. Direct contact inhibits continuous motion and results in a strong increase of the critical Shields number. For identical beads, we found two different regimes for the onset of continuous motion. Depending on the substrate geometry, the upstream particle may start to roll like a single particle passing the downstream neighbor or it may push its downstream neighbor forward. In the latter case, the downstream sphere rolls while the upstream bead slides in contact with the downstream neighbor. Both regimes yield about the same critical Shields number although the critical Shields number for single particle motion differs by about 50%. If particle contact is avoided by a sudden jump in the Shields number, the critical Shields number for onset of continuous particle motion can be reduced considerably. Finally, the lowest critical Shields numbers for dislodging buried beads in the configurations studied coincides with the critical Shields number for incipient motion of irregular granular beds

Physiological and Clinical Aspects of Bioactive Peptides from Marine Animals

Biological molecules in nutraceuticals and functional foods have proven physiological properties to treat human chronic diseases. These molecules contribute to applications in the food and pharmaceutical industries by preventing food spoilage and cellular injury. Technological advancement in the screening and characterization of bioactive peptides has enabled scientists to understand the associated molecules. Consistent collaboration among nutritionists, pharmacists, food scientists, and bioengineers to find new bioactive compounds with higher therapeutic potential against nutrition-related diseases highlights the potential of the bioactive peptides for food and pharmaceutic industries. Among the popular dietary supplements, marine animals have always been considered imperative due to their rich nutritional values and byproduct use in the food and pharmaceutical industries. The bioactive peptides isolated from marine animals are well-known for their higher bioactivities against human diseases. The physiological properties of fish-based hydrolyzed proteins and peptides have been claimed through in vitro, in vivo, and clinical trials. However, systematic study on the physiological and clinical significance of these bioactive peptides is scarce. In this review, we not only discuss the physiological and clinical significance of antioxidant and anticancer peptides derived from marine animals, but we also compare their biological activities through existing in vitro and in vivo studies

NACA 2412 performance modification via using AFC

The NACA 2412 profile was numerically studied via employing 2D-DNS and implementing Active Flow Control (AFC), the Reynolds number considered was 6757, being the angle of attack of 8º. Initially, the basic flow without implementing AFC was considered, the point in which the boundary layer separates as well as the y+ value along the profile length were evaluated. A single groove location, just before the separation point, was considered, periodic forcing was employed to both modify the location of the separation point and change the separation area where vortices are present. This was undertaken resulting in a reduction of the drag coefficient while increasing the lift. Via studying a set of frequencies and amplitudes linked with the AFC periodic actuation, it was obtained the optimum set of parameters to minimize the drag while maximizing the lift.Postprint (published version

Melting Curves of Triolein Polymorphs

High‐pressure treatment is a promising option for improving mechanical properties and processing parameters of fat‐containing products. To identify optimum processing windows, melting curves, crystallization kinetics, and pathways for transferring the optimized structures to atmospheric pressure need to be known. Here, we provide melting curves of different polymorphic forms of triolein in the industrially relevant pressure range. The melting points of different polymorphic forms are detected optically in thin samples during stepwise changes of pressure or temperature. For cross‐nucleated spherulites, this method allows determining the respective melting points of nuclei and overgrown structures. Tracing the melting curves to atmospheric pressure confirms previous identification of the polymorphic forms at high pressure and enables identifying a previously reported but undefined structure as the β2‐form. Employing Raman spectroscopy, it is confirmed that the polymorph remained unaltered during the pressure release. With increasing pressure, the melting curves of the different polymorphic forms approach each other until they successively merge at the highest pressure levels studied

Easy and versatile coating approach for long-living white hybrid light-emitting diodes

Herein, we provide a new easy-to-do protocol for preparing luminescent rubber-like materials based on a wide palette of compounds, such as small-molecules, quantum dots, polymers, and coordination complexes. The combination of this new protocol with that for preparing similar rubbers based on fluorescent proteins states the universal character of our approach. This is further assessed by using comprehensive spectroscopic and rheological investigations. Furthermore, the novel luminescent rubbers are applied as down-converting packing systems to develop white hybrid light-emitting diodes (WHLEDs), which are heralded as a solid alternative to achieve energy-saving, solid-state, and white-emitting sources in the coming future. As such, the current work also provides a clear prospect of this emerging lighting technology by means of a direct comparison among WHLEDs fabricated with all the above-mentioned down-converting systems. Here, the use of rubbers based on coordination complexes outperforms the others in terms of both luminous efficiency and colour quality with an unprecedented stability superior to 1000 h under continuous operation conditions. This represents an order of magnitude enhancement compared to the state-of-the-art WHLEDs, while keeping luminous efficiencies of around 100 lm W−1