Synthesis, Characterization and Potential Antimicrobial Activity of Selenium Nanoparticles Stabilized with Cetyltrimethylammonium Chloride.

Selenium nanoparticles (Se NPs) have a number of unique properties that determine the use of the resulting nanomaterials in various fields. The focus of this paper is the stabilization of Se NPs with cetyltrimethylammonium chloride (CTAC). Se NPs were obtained by chemical reduction in an aqueous medium. The influence of the concentration of precursors and synthesis conditions on the size of Se NPs and the process of micelle formation was established. Transmission electron microscopy was used to study the morphology of Se NPs. The influence of the pH of the medium and the concentration of ions in the sol on the stability of Se micelles was studied. According to the results of this study, the concentration of positively charged ions has a greater effect on the particle size in the positive Se NPs sol than in the negative Se NPs sol. The potential antibacterial and fungicidal properties of the samples were studied on Escherichia coli, Micrococcus luteus and Mucor. Concentrations of Se NPs stabilized with CTAC with potential bactericidal and fungicidal effects were discovered. Considering the revealed potential antimicrobial activity, the synthesized Se NPs-CTAC molecular complex can be further studied and applied in the development of veterinary drugs, pharmaceuticals, and cosmetics.

TRamWAy: mapping physical properties of individual biomolecule random motion in large-scale single-particle tracking experiments.

MOTIVATION: Single-molecule localization microscopy allows studying the dynamics of biomolecules in cells and resolving the biophysical properties of the molecules and their environment underlying cellular function. With the continuously growing amount of data produced by individual experiments, the computational cost of quantifying these properties is increasingly becoming the bottleneck of single-molecule analysis. Mining these data requires an integrated and efficient analysis toolbox. RESULTS: We introduce TRamWAy, a modular Python library that features: (i) a conservative tracking procedure for localization data, (ii) a range of sampling techniques for meshing the spatio-temporal support of the data, (iii) computationally efficient solvers for inverse models, with the option of plugging in user-defined functions and (iv) a collection of analysis tools and a simple web-based interface. AVAILABILITY AND IMPLEMENTATION: TRamWAy is a Python library and can be installed with pip and conda. The source code is available at https://github.com/DecBayComp/TRamWAy.

Statistical Tests for Force Inference in Heterogeneous Environments.

We devise a method to detect and estimate forces in a heterogeneous environment based on experimentally recorded stochastic trajectories. In particular, we focus on systems modeled by the heterogeneous overdamped Langevin equation. Here, the observed drift includes a "spurious" force term when the diffusivity varies in space. We show how Bayesian inference can be leveraged to reliably infer forces by taking into account such spurious forces of unknown amplitude as well as experimental sources of error. The method is based on marginalizing the force posterior over all possible spurious force contributions. The approach is combined with a Bayes factor statistical test for the presence of forces. The performance of our method is investigated analytically, numerically and tested on experimental data sets. The main results are obtained in a closed form allowing for direct exploration of their properties and fast computation. The method is incorporated into TRamWAy, an open-source software platform for automated analysis of biomolecule trajectories.

The Stress and Vascular Catastrophes in Newborn Rats: Mechanisms Preceding and Accompanying the Brain Hemorrhages.

In this study, we analyzed the time-depended scenario of stress response cascade preceding and accompanying brain hemorrhages in newborn rats using an interdisciplinary approach based on: a morphological analysis of brain tissues, coherent-domain optical technologies for visualization of the cerebral blood flow, monitoring of the cerebral oxygenation and the deformability of red blood cells (RBCs). Using a model of stress-induced brain hemorrhages (sound stress, 120 dB, 370 Hz), we studied changes in neonatal brain 2, 4, 6, 8 h after stress (the pre-hemorrhage, latent period) and 24 h after stress (the post-hemorrhage period). We found that latent period of brain hemorrhages is accompanied by gradual pathological changes in systemic, metabolic, and cellular levels of stress. The incidence of brain hemorrhages is characterized by a progression of these changes and the irreversible cell death in the brain areas involved in higher mental functions. These processes are realized via a time-depended reduction of cerebral venous blood flow and oxygenation that was accompanied by an increase in RBCs deformability. The significant depletion of the molecular layer of the prefrontal cortex and the pyramidal neurons, which are crucial for associative learning and attention, is developed as a consequence of homeostasis imbalance. Thus, stress-induced processes preceding and accompanying brain hemorrhages in neonatal period contribute to serious injuries of the brain blood circulation, cerebral metabolic activity and structural elements of cognitive function. These results are an informative platform for further studies of mechanisms underlying stress-induced brain hemorrhages during the first days of life that will improve the future generation's health.

Integrated optoelectronic probe including a vertical cavity surface emitting laser for laser Doppler perfusion monitoring.

An integrated optoelectronic probe with small dimensions, for direct-contact laser Doppler blood flow monitoring has been realized. A vertical cavity surface emitting laser (VCSEL), and a chip with photodetectors and all necessary electronics are integrated in a miniature probe head connected to a laptop computer. The computer sound processor is utilized for acquisition and digital signal processing of the incoming Doppler signal. In this paper, the design of the laser Doppler perfusion monitor is described and its performance is evaluated. We demonstrate our perfusion monitor to be less sensitive to subject motion than a commercial fiber-optic device. For medium and high perfusion levels, the performance of our integrated probe is comparable to the fiberoptic flowmeter containing a normal edge-emitting laser diode. For very low perfusion levels, the signal-to-noise ratio of the fiber-optic device is higher. This difference can mainly be attributed to the shorter coherence length of the VCSEL compared with the edge-emitting laser diode.

Optical sectioning in wide-field microscopy obtained by dynamic structured light illumination and detection based on a smart pixel detector array.

Optical sectioning in wide-field microscopy is achieved by illumination of the object with a continuously moving single-spatial-frequency pattern and detecting the image with a smart pixel detector array. This detector performs an on-chip electronic signal processing that extracts the optically sectioned image. The optically sectioned image is directly observed in real time without any additional postprocessing.

Engineering of coenzyme specificity of formate dehydrogenase from Saccharomyces cerevisiae.

A eukaryotic formate dehydrogenase (EC 1.2.1.2, FDH) with its substrate specificity changed from NAD(+) to NADP(+) has been constructed by introducing two single-point mutations, Asp(196)-->Ala (D196A) and Tyr(197)-->Arg (Y197R). The mutagenesis was based on the results of homology modelling of a NAD(+)-specific FDH from Saccharomyces cerevisiae (SceFDH) using the Pseudomonas sp.101 FDH (PseFDH) crystal structure as a template. The resulting model structure suggested that Asp(196) and Tyr(197) mediate the absolute coenzyme specificity of SceFDH for NAD(+).

Laser Doppler perfusion imaging with a complimentary metal oxide semiconductor image sensor.

We utilized a complimentary metal oxide semiconductor video camera for fast flow imaging with the laser Doppler technique. A single sensor is used for both observation of the area of interest and measurements of the interference signal caused by dynamic light scattering from moving particles inside scattering objects. In particular, we demonstrate the possibility of imaging the distribution of the moving red blood cell concentration. This is a first step toward laser Doppler imaging without scanning parts, leading to a much faster imaging procedure than with existing mechanical laser Doppler perfusion imagers.