Macroporous poly(vinyl alcohol) cryogels (PVACGs) are physical gels formed via cryogenic processing of polymer solutions. The properties of PVACGs depend on many factors: the characteristics and ...concentration of PVA, the absence or presence of foreign solutes, and the freezing-thawing conditions. These factors also affect the macroporous morphology of PVACGs, their total porosity, pore size and size distribution, etc. In this respect, there is the problem with developing a scientifically-grounded classification of the morphological features inherent in various PVACGs. In this study PVA cryogels have been prepared at different temperatures when the initial polymer solutions contained chaotropic or kosmotropic additives. After the completion of gelation, the rigidity and heat endurance of the resultant PVACGs were evaluated, and their macroporous structure was investigated using optical microscopy. The images obtained were treated mathematically, and deep neural networks were used for the classification of these images. Training and test sets were used for their classification. The results of this classification for the specific deep neural network architecture are presented, and the morphometric parameters of the macroporous structure are discussed. It was found that deep neural networks allow us to reliably classify the type of additive or its absence when using a combined dataset.
SDN (Software-Defined Network) is a network in which the control plane functionality is separated from the packet forwarding layer. The paper is devoted to the study of the SDN security. A comparison ...of neural networks with various parameters on existing dataset is presented. CSE-CIC-IDS2018 dataset 12 provided by Canadian Institute for Cybersecurity (CIC) on AWS (Amazon Web Services) was chosen. It contains of the most relevant types of network attacks. Results show that a simple neural network, such as a multi-layer perceptron, can be used to provide basic protection against most attacks. To provide more reliable protection, complex neural networks should be used. The presented LSTM-based model showed a very good result of intrusion detection.
This paper considers the possibility of using machine learning methods in solving the problem of intrusion detection in software-defined networks (SDN). The work is devoted to the research and ...development of a network attack classifier, which is a core of the intrusion detection systems. To evaluate the methods, an existing data set was used, which includes network traffic records with a several different network attack scenarios. A comparison of machine learning methods implementing neural networks on a selected data set is presented. Based on the results, it can be concluded that the task of intrusion detection in software-defined networks can be successfully solved using deep neural networks.
Benthic marine organisms such as mollusks are often exposed to periodic oxygen deficiency (due to the tidal exposure and/or seasonal expansion of the oxygen-deficient dead zones) and pollution by ...metals e.g., cadmium, (Cd). These stressors can strongly affect mollusks' survival; however, physiological mechanisms of their combined effects are not fully understood. We studied the effects of Cd exposure on metabolic responses to prolonged anoxia and subsequent recovery in anoxia-tolerant intertidal mollusks Crassostrea virginica (eastern oysters). Anoxia led to an onset of anaerobiosis indicated by accumulation of l-alanine, acetate, and succinate. Prolonged anoxia (for 6 days) caused a decline in the maximum activity of electron transport chain and ADP-stimulated (state 3) oxygen uptake by mitochondria (MO(2)), but no change in the resting (state 4) MO(2) of oyster mitochondria, along with a slight but significant reduction of mitochondrial respiratory control ratio. During reoxygenation, there was a significant overshoot of mitochondrial MO(2) (by up to 70% above the normoxic steady-state values) in control oysters. Mild mitochondrial uncoupling during prolonged shutdown in anoxic tissues and a subsequent strong stimulation of mitochondrial flux during recovery may help to rapidly restore redox status and protect against elevated reactive oxygen species formation in oysters. Exposure to Cd inhibits anaerobic metabolism, abolishes reoxygenation-induced stimulation of mitochondrial MO(2), and leads to oxidative stress (indicated by accumulation of DNA lesions) and a loss of mitochondrial capacity during postanoxic recovery. This may result in increased sensitivity to intermittent hypoxia and anoxia in Cd-exposed mollusks and will have implications for their survival in polluted estuaries and coastal zones.
SERS is widely used as a detection procedure in various analytical applications due to high sensitivity. One of the stages in the development of such methods is the identification of the compound to ...be quantified using reference spectra. High-intensity reference SERS spectra without extraneous bands are obtained in a wide spectral interval for an important analyte (2,3-diaminophenazine), the Raman scattering of which is enhanced by aggregated hydroxylamine sols of silver nanoparticles.
The possibilities that open up when using instrumental methods such as voltammetry, surface-enhanced Raman spectroscopy (SERS), and mass spectrometry in tandem with enzymatic catalysis are ...considered. The basic principles of operation of electrochemical biosensors based on oxidases and dehydrogenases are described. It is shown that biosensors based on cyclic enzymatic reactions and substrate recycling have the best sensitivity. Variants of a significant improvement in the analytical capabilities of biosensor analysis due to the application of polymers for effective modification of the electrode surface and nondestructive immobilization of enzymes are considered. The data demonstrating how the use of enzyme labels expands the range of bioanalytical applications of SERS are presented. The possibility of a highly sensitive measurement of the activity of enzyme labels (peroxidase, alkaline phosphatase, β-galactosidase) by SERS, in fact, opens up a new universal platform for the development of protocols to determine various antigens. The main trends in the methodology development of proteomic studies by mass spectrometry and the role of proteases in the design of mass spectrometric experiments are considered on the example of the most commonly used proteases.
Nanosized polymer-enzyme films were fabricated on graphite surfaces via a sequential two-stage adsorption of the pH- and thermoresponsive polymer, viz., linear poly(
N
,
N
-dimethylaminoethyl ...methacrylate) (PDMAEMA), and the enzyme, viz., choline oxidase (ChO). The influence of the conditions (pH and temperature), which are applied for deposition of the polymer onto graphite surface, on electrochemical responses of the polymer-enzyme sensor constructs and kinetic parameters of enzymatic oxidation of choline by ChO integrated into the polymer-enzyme films was revealed. Stimuli-sensitivity of PDMAEMA was found to control the properties of the formed polymer coatings (surface coverage, film thickness and roughness), which decisively determine the amount of the ChO bound by the polymer film and, consequently, the resultant electrochemical characteristics of the polymer-enzyme sensor constructs.
Anomalous optical response of the metasurface, fabricated from regular silicon resonators is investigated. The resonators have form of two-dimensional regular bars that are covered by nano-thin ...silver film. Computer simulations as well as real experiment demonstrate deep minima in the reflectance in the optical spectral range. We believe the resonances are due to the excitation of propagating and localized surface em waves. The multiple metal-dielectric resonances result in much enhanced local electromagnetic fields on the surface of the resonators. To investigate the surface enhanced Raman scattering (SERS) effect the metasurface is covered by molecules of 4-mercapto-phenylboronic acid that form covalent bonds with the silver layer. We obtain over
10
5
enhancement of the Raman scattering, by direct matching Raman signals from the metasurface and the flat silver surface. The designed metasurface is used as an effective SERS substrate.
Bioinformatics tools are imperative for the in depth analysis of heterogeneous high-throughput data. Most of the software tools are developed by specific laboratories or groups or companies wherein ...they are designed to perform the required analysis for the group. However, such software tools may fail to capture "what the community needs in a tool". Here, we describe a novel community-driven approach to build a comprehensive functional enrichment analysis tool. Using the existing FunRich tool as a template, we invited researchers to request additional features and/or changes. Remarkably, with the enthusiastic participation of the community, we were able to implement 90% of the requested features. FunRich enables plugin for extracellular vesicles wherein users can download and analyse data from Vesiclepedia database. By involving researchers early through community needs software development, we believe that comprehensive analysis tools can be developed in various scientific disciplines.
The Role of Sphingolipids in Cardiovascular Pathologies Alessenko, A. V.; Lebedev, A. T.; Kurochkin, I. N.
Biochemistry (Moscow). Supplement. Series B, Biomedical chemistry,
04/2019, Letnik:
13, Številka:
2
Journal Article
Recenzirano
—
Cardiovascular diseases (CVD) remain the leading cause of death in industrialized countries. One of the most important risk factors for atherosclerosis is hypercholesterolemia; its diagnostics is ...mainly based on regular analysis of the lipid profile, including the determination of total cholesterol, low and high density lipoprotein cholesterol, and triglycerides. However, in recent years, much attention has been paid to the crosstalk between metabolic pathways of cholesterol and sphingolipid biosynthesis. Sphingolipids are a group of lipids that include a molecule of sphingosine aliphatic alcohol. These include sphingomyelins, cerebrosides, gangliosides, ceramides, sphingosines, and sphingosine-1-phosphate. It has been found that sphingolipid catabolism is associated with cholesterol catabolism. However, the exact mechanism of this interaction still remains unknown. Ceramide attracts particular attention as a CVD inducer. Aggregated lipoproteins isolated from atherosclerotic zones were found to be enriched with ceramides. Ceramide and sphingosine levels increase after ischemia/reperfusion of the heart, in the infarction area and in the blood, as well as in hypertension. Sphingosine-1-phosphate (S-1-P) exhibits pronounced cardioprotective properties. Its quantity sharply decreased during ischemia and myocardial infarction. S-1-P predominated in the structure of high-density lipoproteins (HDL), where it has a significant impact on their multiple functions. An increase in ceramide and sphingosine and a decrease in S-1-P levels during progression of coronary heart disease may be an important factor in the development of atherosclerosis. It is proposed to use determination of sphingolipid levels in the blood plasma as markers for early diagnostics of cardiac ischemia and in hypertension in humans. Recently, intensive studies have been undertaken to create drugs that can correct S-1-P metabolism. The most successful developments include agents targeted to the S-1-P receptor, which mediates all S-1-P effects. Chromatography-mass spectrometry is proposed as the main method for testing these lipids.
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