On the convective nature of the instability of a front undergoing a supercritical Turing bifurcation

Fronts are traveling waves in spatially extended systems that connect two different spatially homogeneous rest states. If the rest state behind the front undergoes a supercritical Turing instability, then the front will also destabilize. On the linear level, however, the front will be only convectively unstable since perturbations will be pushed away from the front as it propagates. In other words, perturbations may grow but they can do so only behind the front. It is of interest to show that this behavior carries over to the full nonlinear system. It has been successfully done in a case study by Ghazaryan and Sandstede [A. Ghazaryan, B. Sandstede, Nonlinear convective instability of Turing-unstable fronts near onset: a case study, SIAM J. Appl. Dyn. Syst. 6 (2007) 319–347]. In the present paper, analogous results are obtained for the same system as in Ghazaryan and Sandstede (2007), but for a different parameter regime.     

Precise Speed Estimation From a Low-Resolution Encoder by Dual-Sampling-Rate Observer

This paper describes an effective way to estimate state variables, such as motor speed and disturbance from a low-resolution encoder at low speed by using the dual-sampling-rate observer. The dual-sampling-rate observer estimates the state variables at every DSP control period and correct the estimation error at the instant that the measurement signal is detected. A novel pole assignment method, which considers the relation of the estimation and error correction periods, is proposed to maintain the stability for long error correcting period. Moreover, the dual-sampling-rate observer can be applied for higher order systems since it is generalized in state space. The effectiveness of the observer is verified through various simulations and experiments     

Functionalization of hybrid poly(n‐isopropylacrylamide) hydrogels for Escherichia coli cell capture via adsorbed intermediate dye molecule

Poly(n‐isopropylacrylamide) Laponite (PNIPAM‐Lap) hybrid hydrogels, which use the synthetic clay Laponite as a crosslinker, permanently adsorb cationic laser dyes out of solution. This proof‐of‐concept expounds on this capability by adsorbing an intermediate dye molecule and using it as the foundation for successfully conjugating microbial antibodies to the surface of a PNIPAM hydrogel. The study involves using acriflavinium chloride molecules, adsorbed by a PNIPAM‐Lap hydrogel from an acriflavine laser dye solution, as an intermediate molecule to attach antibodies raised against E. coli to the hydrogel and demonstrate cell capture. Furthermore, this system exemplifies a novel biotechnological platform for greatly expanding PNIPAM hydrogels' capabilities and applicability through conjugation chemistry to surface‐bound molecules. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41557.     

Interface reactions between rutile coatings and molten aluminium or AlSi7Mg0.6 alloy

Rutile coatings deposited on corundum substrates are considered as promising functional elements improving the efficiency of the filtration of oxide inclusions out of aluminium melts. This contribution describes the reactions between rutile and two kinds of the aluminium melts and discusses the consequences of these reactions for the filtration process. It was found that the contact of rutile coatings with molten aluminium leads to the formation of a corundum layer at the solid/liquid interface. The exposure of the rutile coatings to molten AlSi7Mg0.6 alloy produces an interface layer of MgTiO₃. The interface layers possess defined orientation relationship to rutile which is characteristic for locally heteroepitaxial growth. The density functional theory calculations revealed that the TiO₂/α-Al₂O₃ and TiO₂/MgTiO₃ interfaces with the orientation relationships observed experimentally have low interface energies. The mechanisms of the interface layer formation and the impact of these layers on the degradation of the rutile coatings are discussed.     

Protein‐Corona‐by‐Design in 2D: A Reliable Platform to Decode Bio–Nano Interactions for the Next‐Generation Quality‐by‐Design Nanomedicines

Hard corona (HC) protein, i.e., the environmental proteins of the biological medium that are bound to a nanosurface, is known to affect the biological fate of a nanomedicine. Due to the size, curvature, and specific surface area (SSA) 3‐factor interactions inherited in the traditional 3D nanoparticle, HC‐dependent bio–nano interactions are often poorly probed and interpreted. Here, the first HC‐by‐design case study in 2D is demonstrated that sequentially and linearly changes the HC quantity using functionalized graphene oxide (GO) nanosheets. The HC quantity and HC quality are analyzed using NanoDrop and label‐free liquid chromatography–mass spectrometry (LC‐MS) followed by principal component analysis (PCA). Cellular responses (uptake and cytotoxicity in J774 cell model) are compared using imaging cytometry and the modified lactate dehydrogenase assays, respectively. Cellular uptake linearly and solely correlates with HC quantity (R² = 0.99634). The nanotoxicity, analyzed by retrospective design of experiment (DoE), is found to be dependent on the nanomaterial uptake (primary), HC composition (secondary), and nanomaterial exposure dose (tertiary). This unique 2D design eliminates the size–curvature–SSA multifactor interactions and can serve as a reliable screening platform to uncover HC‐dependent bio–nano interactions to enable the next‐generation quality‐by‐design (QbD) nanomedicines for better clinical translation.     

Service-oriented visualization applied to medical data analysis

With the era of Grid computing, data driven experiments and simulations have become very advanced and complicated. To allow specialists from various domains to deal with large datasets, aside from developing efficient extraction techniques, it is necessary to have available computational facilities to visualize and interact with the results of an extraction process. Having this in mind, we developed an Interactive Visualization Framework, which supports a service-oriented architecture. This framework allows, on one hand visualization experts to construct visualizations to view and interact with large datasets, and on the other hand end-users (e.g., medical specialists) to explore these visualizations irrespective of their geographical location and available computing resources. The image-based analysis of vascular disorders served as a case study for this project. The paper presents main research findings and reports on the current implementation status.     

The prospects of brewery waste application in biohydrogen production by photofermentation of Rhodobacter sphaeroides

Selection of the source for biohydrogen (H₂) production is essential, since it affects bacterial metabolism. Pure organic substrates give fast H₂ generation with high yields, but they increase the production cost. Using industrial wastes as a source provides inexpensive energy generation with simultaneous waste utilization. H₂ production by photofermentation of Rhodobacter sphaeroides is monitored during cultivation on brewery waste. Maximum specific growth rate is observed for 5–10% waste containing media. H₂ production by cells, grown on waste, is detected at 48–96 h of growth; it is comparable or higher than that of control medium with expensive carbon and nitrogen sources. N,N′-dicyclohexylcarbodiimide-sensitive ATPase activity of R. sphaeroides membrane vesicles from growth on waste containing media is 1.6–1.7-fold higher compared to control, correlating with enhanced H₂ production. Growth medium containing optimal amount of wastes may be a successful alternative to expensive media for high H₂ yield in R. sphaeroides during photofermentation.     

On the Role of Structural Imperfections of Graphene in Resonant Tunneling through Localized States in the h-BN Barrier of van-der-Waals Heterostructures

Semiconductors - Resonant tunneling through defect levels in the h-BN barrier of van-der-Waals heterostructures is investigated. The effect of multiplication of the tunneling resonances through...     

Growth characteristics and hydrogen production by Rhodobacter sphaeroides using various amino acids as nitrogen sources and their combinations with carbon sources

Some amino acids (alanine, asparagine, glutamate, glycine, proline, and tyrosine) were used as nitrogen sources in combination with carbon sources (succinate and malate) to study growth properties and H₂ production by purple non-sulfur bacterium Rhodobacter sphaeroides strains A-10 and D-3. Both strains produced H₂ in succinate–glutamate and malate–glutamate media. Succinate was a better carbon source than malate. In comparison with strain D-3, strain A-10 was able to utilize proline, alanine or tyrosine as nitrogen sources in succinate medium and to produce H₂. Both strains were unable to produce H₂ in the presence of asparagine or glycine as nitrogen sources. N,N′-dicyclohexylcarbodiimide, the F₀F₁-ATPase inhibitor, led to marked inhibition of H₂ production activity of R. sphaeroides. The results suggest that the R. sphaeroides cells growth can be achieved by the use of a large diversity of substrates but only some of them can increase the H₂ production rate.