Wasserstein autoregressive models for density time series

Data consisting of time-indexed distributions of cross-sectional or intraday returns have been extensively studied in finance, and provide one example in which the data atoms consist of serially dependent probability distributions. Motivated by such data, we propose an autoregressive model for density time series by exploiting the tangent space structure on the space of distributions that is induced by the Wasserstein metric. The densities themselves are not assumed to have any specific parametric form, leading to flexible forecasting of future unobserved densities. The main estimation targets in the order-p Wasserstein autoregressive model are Wasserstein autocorrelations and the vector-valued autoregressive parameter. We propose suitable estimators and establish their asymptotic normality, which is verified in a simulation study. The new order-p Wasserstein autoregressive model leads to a prediction algorithm, which includes a data driven order selection procedure. Its performance is compared to existing prediction procedures via application to four financial return data sets, where a variety of metrics are used to quantify forecasting accuracy. For most metrics, the proposed model outperforms existing methods in two of the data sets, while the best empirical performance in the other two data sets is attained by existing methods based on functional transformations of the densities.     

New high temperature amorphous protective coatings for Mg2Si thermoelectric material

Magnesium silicide is one of the most promising, inexpensive, environment friendly and low density (1.99?g?cm^?3) thermoelectric material. These attributes distinguish it from other well-known thermoelectric materials and therefore it is currently intensively studied. Since thermoelectric materials are used in elevated temperatures, they are prone to oxygen corrosion which results in deterioration of their properties and therefore require anticorrosion protection. The aim of the work was to develop anticorrosive coating for magnesium silicide using silane-based, amorphous coatings. High purity Mg₂Si samples were prepared by self-propagating high-temperature synthesis (SHS) and hot-pressing method supported by induction heater. The structural and phase compositions of the obtained samples were examined by means of X-ray diffraction (XRD) method and chemical composition analysis by scanning electron microscopy SEM, combined with EDS method. Fourier-transform infrared spectroscopy FT-IR, Raman spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), temperature-programmed reduction (TPR) and temperature-programmed oxidation (TPOx) methods were used in order to determine chemical stability of prepared samples. In final step, magnesium silicide samples were covered with selected amorphous coatings by dip-coating method and then annealed in Ar gas atmospheres in various temperatures between 400–550?°C. The obtained coatings were characterized using SEM-EDS and reflectance spectroscopy method.     

Arabidopsis Phototropins Participate in the Regulation of Dark-Induced Leaf Senescence

Senescence is the final stage of plant development, affecting individual organs or the whole organism, and it can be induced by several environmental factors, including shading or darkness. Although inevitable, senescence is a complex and tightly regulated process, ensuring optimal remobilization of nutrients and cellular components from senescing organs. Photoreceptors such as phytochromes and cryptochromes are known to participate in the process of senescence, but the involvement of phototropins has not been studied to date. We investigated the role of these blue light photoreceptors in the senescence of individually darkened Arabidopsis thaliana leaves. We compared several physiological and molecular senescence markers in darkened leaves of wild-type plants and phototropin mutants (phot1, phot2, and phot1phot2). In general, all the symptoms of senescence (lower photochemical activity of photosystem II, photosynthetic pigment degradation, down-regulation of photosynthetic genes, and up-regulation of senescence-associated genes) were less pronounced in phot1phot2, as compared to the wild type, and some also in one of the single mutants, indicating delayed senescence. This points to different mechanisms of phototropin operation in the regulation of senescence-associated processes, either with both photoreceptors acting redundantly, or only one of them, phot1, playing a dominant role.     

Storage of hydrogen,natural gas,and carbon dioxide – Geological and legal conditions

The analysis of geological and reservoir conditions of the underground storage of hydrogen, methane, and carbon dioxide, that are important when choosing rock formations for the storage of gas, was presented. Physico-chemical properties of the discussed gases, affecting underground storage, were taken into account. Aquifers, hydrocarbon reservoirs, and caverns leached in salt rocks were analyzed. Legal aspects of underground gas storage were indicated.The physico-chemical conditions of the gases considered (especially molecular mass, and dynamic viscosity) are important for the selection of geological structures for their storage. The reservoir tightness is one of the most important geological and reservoir conditions when taking the appropriate porosity and permeability of rocks building underground storage sites into account. Salt caverns should be mainly used for hydrogen storage due to the tightness of rock salt. Geochemical and microbiological interactions affecting the operation of the underground storage site and its tightness are especially important and should be taken into account. The size of the underground storage site, while not as crucial in the case of H₂ storage, is important for CO₂ storage. When it comes to reservoir conditions, the amount of cushion gas and storage efficiency are important. The legal status of gas storage sites is highly variable. While there are existing regulations regarding natural gas storage, CO₂ storage requires further legislation. In the case of H₂ storage legal regulations need to be developed based on the experience of storage of other gases. The potential competition from other entities focused on the use of underground space for gas storage should be taken into account.     

The Influence of Cold Atmospheric Pressure Plasma-Treated Media on the Cell Viability,Motility, and Induction of Apoptosis in Human Non-Metastatic (MCF7) and Metastatic (MDA-MB-231) Breast Cancer Cell Lines

Breast cancer remains the most common type of cancer, occurring in middle-aged women, and often leads to patients’ death. In this work, we applied a cold atmospheric pressure plasma (CAPP)-based reaction-discharge system, one that is unique in its class, for the production of CAPP-activated media (DMEM and Opti-MEM); it is intended for further uses in breast cancer treatment. To reach this aim, different volumes of DMEM or Opti-MEM were treated by CAPP. Prepared media were exposed to the CAPP treatment at seven different time intervals and examined in respect of their impact on cell viability and motility, and the induction of the apoptosis in human non-metastatic (MCF7) and metastatic (MDA-MB-231) breast cancer cell lines. As a control, the influence of CAPP-activated media on the viability and motility, and the type of the cell death of the non-cancerous human normal MCF10A cell line, was estimated. Additionally, qualitative and quantitative analyses of the reactive oxygen and nitrogen species (RONS), generated during the CAPP operation in contact with analyzed media, were performed. Based on the conducted research, it was found that 180 s (media activation time by CAPP) should be considered as the minimal toxic dose, which significantly decreases the cell viability and the migration of MDA-MB-231 cells, and also disturbs life processes of MCF7 cells. Finally, CAPP-activated media led to the apoptosis of analyzed cell lines, especially of the metastatic MDA-MB-231 cell line. Therefore, the application of the CAPP system may be potentially applied as a therapeutic strategy for the management of highly metastatic human breast cancer.     

Generation of meso- and microporous structures by pyrolysis of polysiloxane microspheres and by HF etching of SiOC microspheres

The porosity of polysiloxane microspheres obtained by emulsion processing of variably modified polyhydromethylsiloxane (PHMS) and subjected to pyrolysis in an Ar atmosphere at 450–650 °C was studied. Materials having micro- and mesopores with specific surface areas (SSAs) of up to 786 m²/g and pore volumes of up to 0.35 cm³/g were obtained. A high porosity was displayed by the microspheres heated at 600 °C that underwent deep depolymerization processes. Some polysiloxane microspheres were ceramized at temperatures of 1200–1500 °C and were subjected to etching by 35% aqueous HF. The microspheres heated to 1200–1400 °C were free of microcracks, whereas those ceramized at 1500 °C showed microcracks and macropores, although they preserved their spherical structure well. All of the microspheres ceramized at temperatures of 1200–1400 °C had low porosity. HF etching granted high micro- and mesoporosity to the materials ceramized at 1300–1500 °C. Microspheres heated at 1500 °C showed specific surface areas above 1000 m²/g after etching. These microspheres had low oxygen contents and were mostly composed of silicon carbide. Since they also showed macroporosity, HF etching of the polysiloxane microspheres ceramized at 1500 °C could be used to obtain hierarchically mesoporous-macroporous ceramic microspheres.     

Antifungal Activity and Biosynthetic Potential of New Streptomyces sp. MW-W600-10 Strain Isolated from Coal Mine Water

Crop infections by fungi lead to severe losses in food production and pose risks for human health. The increasing resistance of pathogens to fungicides has led to the higher usage of these chemicals, which burdens the environment and highlights the need to find novel natural biocontrol agents. Members of the genus Streptomyces are known to produce a plethora of bioactive compounds. Recently, researchers have turned to extreme and previously unexplored niches in the search for new strains with antimicrobial activities. One such niche are underground coal mine environments. We isolated the new Streptomyces sp. MW-W600-10 strain from coal mine water samples collected at 665 m below ground level. We examined the antifungal activity of the strain against plant pathogens Fusarium culmorum DSM62188 and Nigrospora oryzae roseF7. Furthermore, we analyzed the strain’s biosynthetic potential with the antiSMASH tool. The strain showed inhibitory activity against both fungi strains. Genome mining revealed that it has 39 BGCs, among which 13 did not show similarity to those in databases. Additionally, we examined the activity of the Streptomyces sp. S-2 strain isolated from black soot against F. culmorum DSM62188. These results show that coal-related strains could be a source of novel bioactive compounds. Future studies will elucidate their full biotechnological potential.     

Differentiation of Confectionery Products Based on Mineral Composition

The aim of this investigation was to introduce multivariate techniques for the estimation of confectionery product quality in view of their mineral composition. The concentrations of 14 elements (Ca, Mg, K, Na, P, Co, Mn, Fe, Cr, Ni, Zn, Cu, Cd, and Pb) were determined in confectionery products after wet digestion with nitric acid in an automatic microwave digestion system. The total metal contents were analyzed by flame atomic absorption spectrometry using deuterium background correction. Phosphorus was determined in the form of phosphomolybdate by a spectrophotometric method. Reliability of the procedure was checked by analysis of the certified reference materials tea (NCS DC 73351), cabbage (IAEA-359), and spinach (IAEA-331). Significant correlation coefficients were found between concentrations of Mg, Zn, Ca, K, Na, P, and Fe in the samples analyzed. Application of ANOVA Kruskal–Wallis test revealed dependence between sugar biological provenance and its elemental composition. Macro- and microelement levels in chocolates were significantly influenced by the cocoa content in the final product as well as its geographical origin. Factorial and cluster analyses were applied to the data in order to characterize elemental content of the confectionery products. Based on the mineral composition, it was possible to differentiate chemometrically particular types of sugar, cocoa, and chocolates, which is important from the food authenticity point of view.     

Platinum and Palladium Complexes as Promising Sources for Antitumor Treatments

There is a need for new, safer, and more effective agents to treat cancer. Cytostatics that have transition metals at their core have attracted renewed interest from scientists. Researchers are attempting to use chemotherapeutics, such as cisplatin, in combination therapy (i.e., in order to enhance their effectiveness). Moreover, studies are being carried out to modify molecules, by developing them into multinuclear structures, linking different compounds to commonly used drugs, or encapsulating them in nanoparticles to improve pharmacokinetic parameters, and increase the selectivity of these drugs. Therefore, we attempted to organize recent drug findings that contain palladium and platinum atoms in their structures.     

Functional Properties of Polyurethane Ureteral Stents with PLGA and Papaverine Hydrochloride Coating

Despite the obvious benefits of using ureteral stents to drain the ureters, there is also a risk of complications from 80–90%. The presence of a foreign body in the human body causes disturbances in its proper functioning. It can lead to biofilm formation on the stent surface, which may favor the development of urinary tract infections or the formation of encrustation, as well as stent fragmentation, complicating its subsequent removal. In this work, the effect of the polymeric coating containing the active substance-papaverine hydrochloride on the functional properties of ureteral stents significant for clinical practice were assessed. Methods: The most commonly clinically used polyurethane ureteral Double-J stent was selected for the study. Using the dip-coating method, the surface of the stent was coated with a poly(D,L-lactide-glycolide) (PLGA) coating containing the papaverine hydrochloride (PAP). In particular, strength properties, retention strength of the stent ends, dynamic frictional force, and the fluoroscopic visibility of the stent during X-ray imaging were determined. Results: The analysis of the test results indicates the usefulness of a biodegradable polymer coating containing the active substance for the modification of the surface of polyurethane ureteral stents. The stents coated with PLGA+PAP coating compared to polyurethane stents are characterized by more favorable strength properties, the smaller value of the dynamic frictional force, without reducing the fluoroscopic visibility.