Sensitivity of antioxidant-deficient yeast to hypochlorite and chlorite

Sodium hypochlorite and sodium chlorite are commonly used as disinfectants, and understanding the mechanisms of microbial resistance to these compounds is of considerable importance. In this study, the role of oxidative stress and antioxidant enzymes in the sensitivity of the yeast Saccharomyces cerevisiae to hypochlorite and chlorite was studied. Yeast mutants lacking Cu-Zn superoxide dismutase, but not mutants deficient in cytoplasmic and peroxisomal catalase, were hypersensitive to the action of both hypochlorite and chlorite. Both compounds depleted cellular glutathione, induced the production of reactive oxygen species and decreased the viability of the cells. The toxicity of hypochlorite and chlorite was abolished by hypoxic and anoxic conditions and ameliorated by thiol antioxidants and ascorbate. The results demonstrated that the action of hypochlorite and chlorite involves the formation of superoxide and peroxide and that SOD1 is protective, probably by limiting the formation of hydroxyl radicals and damage to proteins.     

Numerical Modeling of Biomass Pyrolysis—Heat and Mass Transport Models

We consider the pyrolysis of robinia pseudoacacia, which is a common material for biomass gasifiers. We formulate three models of the process, with increasingly detailed physics, best suited for different spatial scales from large to small. For each model, we perform numerical simulations of adaptable complexity and compare the results with the thermogravimetric analysis (TGA) experiments.     

Polymorph Selectivity of Coccolith‐Associated Polysaccharides from Gephyrocapsa Oceanica on Calcium Carbonate Formation In Vitro

Coccolith‐associated polysaccharides (CAPs) are thought to be a key part of the biomineralization process in coccolithophores; however, their role is not fully understood. Two different systems that promote different polymorphs of calcium carbonate are used to show the effect of CAPs on nucleation and polymorph selection in vitro. Using a combination of time‐resolved cryo‐transmission electron microscopy and scanning electron microscopy, the mechanisms of calcite nucleation and growth in the presence of the intracrystalline fraction are examined containing CAPs extracted from coccoliths from Gephyrocapsa oceanica and Emiliania huxleyi, two closely related coccolithophore species. The CAPs extracted from G. oceanica are shown to promote calcite nucleation in vitro, even under conditions favoring the kinetic products of calcium carbonate, vaterite, and aragonite. This is not the case with CAPs extracted from E. huxleyi, suggesting that the functional role of CAPs in vivo may be different between the two species. Additionally, high‐resolution synchrotron powder X‐ray diffraction has revealed that the polysaccharide is located between grain boundaries of both calcite produced in the presence of the CAPs in vitro and biogenic calcite, rather than within the crystal lattice.     

Peroxynitrite: mediator of the toxic action of nitric oxide

Peroxynitrite (oxoperoxonitrate(-1)), anion of peroxynitrous acid, is thought to mediate the toxic action of nitric oxide and superoxide anion. Peroxynitrite is formed in a fast reaction between these species, reacts with all classes of biomolecules, is cytotoxic, and is thought to be involved in many pathological phenomena. Its main reactions involve one- and two-electron oxidation and nitration. Protein nitration is often used as a footprint of peroxynitrite reactions in vivo. Nitration of tyrosine and of tyrosyl residues in proteins may be an important mechanism of derangement of biochemical signal transduction by this compound. However, apparently beneficial effects of peroxynitrite have also been described, among them formation of nitric oxide and nitric oxide donors in reactions of peroxynitrite with thiols and alcohols.     

Immunodetection of Pectic Epitopes,Arabinogalactan Proteins,and Extensins in Mucilage Cells from the Ovules of Pilosella officinarum Vaill. and Taraxacum officinale Agg. (Asteraceae)

The main aim of this study was to compare the cytological difference between ovular mucilage cells in two Asteraceae species—Pilosella officinarum and Taraxacum officinale—in order to determine whether pectic epitopes, arabinogalactan proteins, or extensins are present. The immunocytochemical technique was used. Both the Taracacum and Pilosella genera have been used recently as models for understanding the mechanisms of apomixis. Knowledge of the presence of signal molecules (pectic epitopes, arabinogalactan proteins, and extensins) can help better understand the developmental processes in these plants during seed growth. The results showed that in Pilosella officinarum, there was an accumulation of pectins in the mucilage, including both weakly and highly esterified pectins, which was in contrast to the mucilage of Taraxacum officinale, which had low amounts of these pectins. However, Taraxacum protoplasts of mucilage cells were rich in weakly methyl-esterified pectins. While the mucilage contained arabinogalactan proteins in both of the studied species, the types of arabinogalactan proteins were different. In both of the studied species, extensins were recorded in the transmitting tissues. Arabinogalactan proteins as well as weakly and highly esterified pectins and extensins occurred in close proximity to calcium oxalate crystals in both Taraxacum and Pilosella cells.     

Non‐Equilibrium Self‐Assembly of Monocomponent and Multicomponent Tubular Structures in Rotating Fluids

When suspended in a denser rotating fluid, lighter particles experience a cylindrically symmetric confining potential that drives their crystallization into either monocomponent or unprecedented binary tubular packing. These assemblies form around the fluid's axis of rotation, can be dynamically interconverted (upon accelerating or decelerating the fluid), can exhibit preferred chirality, and can be made permanent by solidifying the fluid. The assembly can be extended to fluids forming multiple concentric interfaces or to systems of bubbles forming both ordered and “gradient” structures within curable polymers.     

Design of small hand‐launched solar‐powered UAVs: From concept study to a multi‐day world endurance record flight

We present the development process behind AtlantikSolar, a small 6.9 kg hand‐launchable low‐altitude solar‐powered unmanned aerial vehicle (UAV) that recently completed an 81‐hour continuous flight and thereby established a new flight endurance world record for all aircraft below 50 kg mass. The goal of our work is to increase the usability of such solar‐powered robotic aircraft by maximizing their perpetual flight robustness to meteorological deteriorations such as clouds or winds. We present energetic system models and a design methodology, implement them in our publicly available conceptual design framework for perpetual flight‐capable solar‐powered UAVs, and finally apply the framework to the AtlantikSolar UAV. We present the detailed AtlantikSolar characteristics as a practical design example. Airframe, avionics, hardware, state estimation, and control method development for autonomous flight operations are described. Flight data are used to validate the conceptual design framework. Flight results from the continuous 81‐hour and 2,338 km covered ground distance flight show that AtlantikSolar achieves 39% minimum state‐of‐charge, 6.8 h excess time and 6.2 h charge margin. These performance metrics are a significant improvement over previous solar‐powered UAVs. A performance outlook shows that AtlantikSolar allows perpetual flight in a 6‐month window around June 21 at mid‐European latitudes, and that multi‐day flights with small optical‐ or infrared‐camera payloads are possible for the first time. The demonstrated performance represents the current state‐of‐the‐art in solar‐powered low‐altitude perpetual flight performance. We conclude with lessons learned from the three‐year AtlantikSolar UAV development process and with a sensitivity analysis that identifies the most promising technological areas for future solar‐powered UAV performance improvements.     

Chemisorbed PEGylated lipopolymers as sensing film supports for QCM odor sensors

We report application of the PEGylated lipids (PEG lipopolymers) containing disulphide as supports for sensing films for quartz crystal microbalance (QCM) odor sensors. The materials are binding covalently to the surface of gold QCM sensor electrode creating self-assembled cushion. Additional amounts of lipid or lipid-derived materials can be physisorbed on that chemisorbed coating. Both processes do not require much labor and can be performed with minimum instruments in a simple process. The sensors fabricated with the chemisorbed supports are more sensitive to the tested odorants than their non-supported counterparts. Enhanced sensitivity is derived from higher fluidity of the supported films in comparison to the non-supported ones. Discrimination capability among odorants is also better for the sensors with chemisorbed supports than for the non-supported ones—there are no overlaps between the sample groups and the samples are clustered closely within the groups. Overall, the studied supported sensors introduce interesting properties that can be utilized in the odor sensing systems using QCM sensors.     

Kappa Updated Ensemble for drifting data stream mining

Machine Learning - Learning from data streams in the presence of concept drift is among the biggest challenges of contemporary machine learning. Algorithms designed for such scenarios must take...