Electric field induced, superhydrophobic to superhydrophilic switching in multiwalled carbon nanotube papers

Superhydrophobic multiwalled carbon nanotube bucky paper, fabricated after ozonolysis, shows fascinating electrowetting behavior, which could be remarkably tuned by changing key solution variables like the ionic strength, the nature of the electrolyte, and the pH of the water droplet. More significantly, the droplet behavior can be reversibly switched between superhydrophobic, Cassie-Baxter state to hydrophilic, Wenzel state by the application of an electric field, especially below a threshold value.     

Monitoring persistent items in the union of distributed streams

A persistent item in a stream is one that occurs regularly in the stream without necessarily contributing significantly to the volume of the stream. Persistent items are often associated with anomalies in network streams, such as botnet traffic and click fraud. While it is important to track persistent items in an online manner, it is challenging to zero-in on such items in a massive distributed stream. We present the first communication-efficient distributed algorithms for tracking persistent items in a data stream whose elements are partitioned across many different sites. We consider both infinite window and sliding window settings, and present algorithms that can track persistent items approximately with a probabilistic guarantee on the approximation error. Our algorithms have a provably low communication cost, and a low rate of false positives and false negatives, with a high probability. We present detailed results from an experimental evaluation that show the communication cost is small, and that the false positive and false negative rates are typically much lower than theoretical guarantees.     

Suppression of Red Luminescence in Wire Explosion Derived Eu:ZnO

Europium oxide (Eu₂O₃) is coated on zinc (Zn) wire using the electrophoretic deposition process. The coated Zn wire is subjected to the wire explosion process (WEP) which is rapid (< 15 min), and chimie douce (soft chemical, low temperature), in nature; this results in the formation of Eu doped ZnO. The explosion chamber contains oxygen (99.9%) at atmospheric pressure. Electron micrographs indicate that the particle sizes are ～ 80 nm. Diffractogram-based analysis suggests that the crystallite size is ~ 18–20 nm in the as-prepared doped ZnO nanoparticles. Electron paramagnetic resonance shows the presence of Zn vacancies and the cryo-photoluminescence spectrum indicates that Eu exists in the + 3 state. A combined Williamson–Hall plot and Kisielowski’s model based analysis indicates that Eu is a substitutional dopant in WEP derived Eu:ZnO particles. It is estimated that this material has ～ 0.24 at.% doping. This analysis also shows that, unlike another popular material GaN, in the case of ZnO, Eu³⁺ strictly substitutes for Zn²⁺ (i.e., dopant replacing a cation–anion pair does not seem possible). It may be noted that Eu³⁺ in a suitable host is oftentimes reported to be an efficient luminophore. The IR spectra show a band shift from 486 cm^?1 to 493 cm^?1; with peak shifts from 436 cm^?1 to 430 cm^?1 in Raman spectra. These too indicate the presence of Eu in the samples. However, at room temperature, only green luminescence (centered at 534 nm) is observed from the sample indicating (1) high concentrations of O_Zn anti-site defects and Zn vacancies, and (2) concomitant quenching of the luminescence at room temperature. Our results suggest that WEP is viable for synthesizing rare earth doped ceramic materials. However, obtaining efficient phosphors using this approach will likely require, (1) reduction of defect densities, and (2) appropriate passivation using post-processing.     

Heat transfer and fluid flow analysis of non-Newtonian fluid in a microchannel with electromagnetohydrodynamics and thermal radiation

The study of electromagnetohydrodynamics (EMHD) of non-Newtonian fluid plays a significant role for optical design, thermal management of electronic components, and various operations of microfluidic devices. The use of parallel geometry is seen in the circulatory system, extrusion process, and respiratory system. By considering various practical applications, in the current study, the Poiseuille flow of an incompressible Casson liquid between the plates is investigated. The effects of MHD, Joule heating, thermal radiation, modified Darcy's law, and chemical reaction have been taken into account. The dimensional governing equations have been converted into dimensionless equations with pertinent nondimensional quantities. The resulting system of nondimensional system of equations has been analytically solved with nondimensional slip boundary conditions. The graphical results have been displayed with various fluid flow parameters. From the current study, it is concluded that the influence of Darcy number and Casson fluid parameter enhances the velocity profile, but the concentration declines with the enhancement of Casson fluid parameter. The radiation parameter and Prandtl number suppress the temperature profile.     

Do COVID-19 Infections Result in a Different Form of Secondary Hemophagocytic Lymphohistiocytosis

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in significant morbidity and mortality across the world, with no current effective treatments available. Recent studies suggest the possibility of a cytokine storm associated with severe COVID-19, similar to the biochemical profile seen in hemophagocytic lymphohistiocytosis (HLH), raising the question of possible benefits that could be derived from targeted immunosuppression in severe COVID-19 patients. We reviewed the literature regarding the diagnosis and features of HLH, particularly secondary HLH, and aimed to identify gaps in the literature to truly clarify the existence of a COVID-19 associated HLH. Diagnostic criteria such as HScore or HLH-2004 may have suboptimal performance in identifying COVID-19 HLH-like presentations, and criteria such as soluble CD163, NK cell activity, or other novel biomarkers may be more useful in identifying this entity.     

Analysis of oxide and vanadate supports for catalytic hydrogen combustion: Kinetic and mechanistic investigations

Combustion synthesized oxide and vanadate compounds (CeO₂, Fe₂O₃, CeVO₄, and FeVO₄) were tested for catalytic hydrogen combustion. The compounds were characterized by X‐ray diffraction and X‐ray photoelectron spectroscopy. All the four compounds showed good activity and stability for catalytic hydrogen combustion and more than 95% conversion was observed over all the compounds within 500°C. The mechanisms for the reaction over the different classes of compounds (cerium‐based and iron‐based compounds) were proposed on the basis of spectroscopic observations. The main difference in the mechanisms was in the nature of adsorption of H₂ over the sites. The elementary processes for the reaction were proposed, corresponding rate expressions were derived, and the rate parameters for the reaction were estimated using nonlinear regression. Langmuir‐Hinshelwood and Eley‐Rideal mechanisms were also tested for the reaction and the proposed mechanism was compared with these mechanisms. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Exploiting the bioactive properties of essential oils and their potential applications in food industry

Food Science and Biotechnology - Fruits are an abundant source of minerals and nutrients. High nutritional value and easy-to-consume property have increased its demand. In a way to fulfil this...