Improving LIBS analysis of non-flat heterogeneous samples by signals mapping.

Heterogeneous material analysis by the laser-induced breakdown spectroscopy (LIBS) technique is challenging in real practice due to requirements for representative sampling and non-flat surfaces of the samples. Methods complementary to LIBS (plasma imaging, plasma acoustics, sample surface color imaging) have been introduced to improve zinc (Zn) determination in soybean grist material by LIBS. The detailed statistical study revealed that atomic/ionic lines emission and other LIBS signals were distributed normally except for acoustics signals. The correlation between LIBS and complementary signals was rather poor due to the large variability of the particle properties of soybean grist material. Still, analyte line normalization on plasma background emission was rather simple and effective for Zn analysis but required a few hundred spot samplings for representative Zn quantification. Non-flat heterogeneous samples (soybean grist pellets) were analyzed by LIBS mapping but it was demonstrated that the choice of sampling area is crucial for reliably analyte determination.

Raman structural study of ethylene glycol and 1,3-propylene glycol aqueous solutions.

Raman spectra of ethylene glycol (EG) and 1,3-propylene glycol (1,3-PG) aqueous solutions with the diol content from 10 to 90 mol% were measured. The diol content weakly influences the EG and 1,3-PG Raman bands in the spectra of the solutions in the region 250-1800 cm-1. This fact means that the conformational compositions of both the diols do not change significantly with dissolving in water. The intensity of the OH stretching band with respect to the diol bands intensities is the linear function of the ratio of the mole contents of water and the diol in the solutions. The spectral region 2800-3800 cm-1 can be used to evaluate the chemical composition of these binary solutions. DFT modeling of the Raman spectra of EG molecule in water shell confirms the prevalence of the gauche-conformation of EG in the aqueous solutions.

Features of the cytoprotective effect of selenium nanoparticles on primary cortical neurons and astrocytes during oxygen-glucose deprivation and reoxygenation.

The study is aimed at elucidating the effect of selenium nanoparticles (SeNPs) on the death of cells in the primary culture of mouse cerebral cortex during oxygen and glucose deprivation (OGD). A primary cell culture of the cerebral cortex containing neurons and astrocytes was subjected to OGD and reoxygenation to simulate cerebral ischemia-like conditions in vitro. To evaluate the neuroprotective effect of SeNPs, cortical astrocytes and neurons were incubated for 24 h with SeNPs, and then subjected to 2-h OGD, followed by 24-h reoxygenation. Vitality tests, fluorescence microscopy, and real-time PCR have shown that incubation of primary cultured neurons and astrocytes with SeNPs at concentrations of 2.5-10 µg/ml under physiological conditions has its own characteristics depending on the type of cells (astrocytes or neurons) and leads to a dose-dependent increase in apoptosis. At low concentration SeNPs (0.5 µg/ml), on the contrary, almost completely suppressed the processes of basic necrosis and apoptosis. Both high (5 µg/ml) and low (0.5 µg/ml) concentrations of SeNPs, added for 24 h to the cells of cerebral cortex, led to an increase in the expression level of genes Bcl-2, Bcl-xL, Socs3, while the expression of Bax was suppressed. Incubation of the cells with 0.5 µg/ml SeNPs led to a decrease in the expression of SelK and SelT. On the contrary, 5 µg/ml SeNPs caused an increase in the expression of SelK, SelN, SelT, SelP. In the ischemic model, after OGD/R, there was a significant death of brain cells by the type of necrosis and apoptosis. OGD/R also led to an increase in mRNA expression of the Bax, SelK, SelN, and SelT genes and suppression of the Bcl-2, Bcl-xL, Socs3, SelP genes. Pre-incubation of cell cultures with 0.5 and 2.5 µg/ml SeNPs led to almost complete inhibition of OGD/R-induced necrosis and greatly reduced apoptosis. Simultaneously with these processes we observed suppression of caspase-3 activation. We hypothesize that the mechanisms of the protective action of SeNPs involve the activation of signaling cascades recruiting nuclear factors Nrf2 and SOCS3/STAT3, as well as the activation of adaptive pathways of ESR signaling of stress arising during OGD and involving selenoproteins SelK and SelT, proteins of the Bcl-2 family ultimately leading to inactivation of caspase-3 and inhibition of apoptosis. Thus, our results demonstrate that SeNPs can act as neuroprotective agents in the treatment of ischemic brain injuries.

Structure and refractive index of fibrin protofibril aggregates according to laser phase microscopy accompanied by DLS and AFM.

The structures, sizes, and refractive indices (RI) of protein aggregates formed in a fibrinogen-thrombin system are examined using laser phase microscopy (LPM) accompanied by dynamic light scattering (DLS) and atomic force microscopy (AFM) measurements. Fibrin aggregates found in pure fibrinogen and fibrinogen with thrombin solutions by the DLS method, after drying the sample, form complex structures of different shapes and sizes on a glass surface. The LPM reveals submicron-sized dimeric structures in the pure fibrinogen solution, elongated micron-length structures, and rectangular structures in the fibrinogen-thrombin sample. AFM measurements show that the elongated structures form branched fibers, which in turn assembly into rectangular structures. All sizes obtained by LPM and AFM are consistent with DLS measurements. The refractive indices of all the structures, estimated by optical thickness, vary from 1.53 to 1.62, which indicates that they are fibrinogen derivatives. Effective visualization of the structure and determination of the optical properties for fibrin gel indicate that laser phase microscopy is capable of tissue imaging and characterization.

Electro-optical performance of nematic liquid crystals doped with gold nanoparticles.

The effect of gold nanoparticles on the dielectric, electro-optical, and rheological properties of the ZhK-1289 liquid-crystal mixture that define the response time of liquid-crystal devices with a concentration range of 0.06-5 wt% was investigated in this study. A phase diagram of the obtained composites was formed demonstrating an increase in the clearing temperature and a broadening of the mesophase existence range in the case of doping nanoparticles. It was found that in the obtained dispersions there are structural rearrangements in the low concentration range leading to an increase in the lateral bending stiffness of the liquid-crystal matrix, a decrease in the response time and threshold voltage of the Freedericksz transition, and also an increase in the anisotropy of the dielectric permittivity and the refraction index. The improvement of the electro-optical performance of the liquid crystal can be caused by the nanoparticle adsorption of impurity ions, which reduces the field-screening effect in the liquid crystal. According to the results obtained in this study, the optimal values of the physical parameters of liquid-crystal composites doped with gold nanoparticles for their application in practice are achieved in a concentration range of 0.5-1 wt%.

Influence of electromagnetic waves, with maxima in the green or red range, on the morphofunctional properties of multipotent stem cells.

This paper examines the effect of electromagnetic waves, with maxima in the green or red regions of the spectrum, on the morphofunctional state of multipotent mesenchymal stromal cells. The illumination regimes used in our experiments did not lead to any substantial heating of the samples; the physical parameters of the lighting were carefully monitored. When the samples were illuminated with a green light, no significant photostimulatory effect was observed. Red light, on the other hand, had an evident photostimulatory effect. It is shown that photostimulation with a red light decreases the enzymatic activities of mitochondrial dehydrogenases and enhances the viability of cells, their proliferative activity, and their ability to form bone tissue. It is also established that red light stimulates cell proliferation, while not activating the genes that increase the risk of the subsequent malignant transformation of cells or their death. This paper discusses the possible role of hydrogen peroxide in the processes examined.

Protective and adaptogenic role of peroxiredoxin 2 (Prx2) in neutralization of oxidative stress induced by ionizing radiation.

A radioprotective effect of exogenous recombinant peroxiredoxin 2 (Prx2) was revealed and characterized using an animal model of whole body X-ray irradiation at sublethal and lethal doses. Prx2 belongs to an evolutionarily ancient family of peroxidases that are involved in enzymatic degradation of a wide variety of organic and inorganic hydroperoxides. Apart from that, the oxidized form of Prx2 also exhibits chaperone activity, thereby preventing protein misfolding and aggregation under oxidative stress. Intravenous administration of Prx2 in animals at a concentration of 20 µg/g 15 min before exposure to ionizing radiation contributes to a significantly higher survival rate, suppresses the development of leucopenia and thrombocytopenia, as well as protects the bone marrow cells from genome DNA damage. Moreover, injection of Prx2 leads to suppression of apoptosis, stimulates cell proliferation and results in a more rapid recovery of the cell redox state. Exogenous Prx2 neutralizes the effect of the priming dose on the second irradiation of the cells. The radioprotective properties of exogenous Prx2 are stipulated by its broad substrate peroxidase activity, chaperone activity in the oxidized state, and are also due to the signal-regulatory function of Prx2 mediated by the regulation of the level of hydroperoxides as well as via interaction with redox-sensitive regulatory proteins.

Near-surface structure of Nafion in deuterated water.

The swelling of a polymer ion-exchange membrane Nafion in water with various heavy isotope contents (D2O) was studied by photoluminescent UV spectroscopy. The photoluminescence arises because of the presence of sulfonic groups attached to the ends of the perfluorovinyl ether groups that form the tetrafluoroethylene (Teflon) backbone of Nafion. The width of the colloidal region, which is formed near the membrane surface as a result of the outgrowth of Nafion microfibers toward the bulk liquid, varies non-monotonically with D2O content, displaying a narrow maximum in the low concentration region. A significant insight into the unexpected isotopic effects revealed in swelling Nafion in deuterated water is provided. Mainly, the polymer swelling is very sensitive to small changes (on the order of several tens of parts per million) in the content of deuterium, which, for instance, can help in understanding the isotopic effects in living tissues.

Influence of wideband visible light with an padding red component on the functional state of mice embryos and embryonic stem cells.

It is known that visible light, including sunlight and laboratory lighting, adversely affect the development of embryos in vitro. In with article we present a technology for the synthesis of composite screens, capable to photoconvert UV and a part of the blue spectrum into red light with the maximum ~630 nm. It is established that the application of such transformed light with an evident red component raises the chances of embryos to survive and protects embryonic stem cells. To create photoconversion screens, the CdZn/Se quantum dots were obtained, the average size being about 7 nm. When the quantum dots are excited by electromagnetic waves of the UV and blue spectral range, photoluminescence is observed. The average photon energy for photoluminescence is of the order of 2 eV. On the basis of CdZn/Se quantum dots and methylphenylsiloxane polymer, light-transforming composite screens were made. In case of the light-transforming composite screen, the UV component disappeared from the energy spectrum, and the intensity of the blue region of the spectrum was reduced. On the contrary, in the red region (λmax = 630 nm) one can see a little more than two-fold increase of intensity. It is shown that when exposed to 2-cell embryos by transformed light, the proportion of normally developing embryos increases by 20%, the number of dead embryos decreases twice, and number of dead and apoptotic cells was lower in blastocysts, what's decreased by 70%, as compared to the control group. When blastocysts are transferred to the feeder substrate, colonies of embryonic stem cells are formed. Cells obtained from blastocysts irradiated with transformed visible light are in a normal state in 90% of cases and did not change expression levels, biochemistry and morphology for at least 20 passages. It is assumed that the data obtained can be used for the design of systems of efficient cultivation of embryonic cells for tissue engineering and cell therapy.

The role of peroxiredoxin 6 in neutralization of X-ray mediated oxidative stress: effects on gene expression, preservation of radiosensitive tissues and postradiation survival of animals.

Peroxiredoxins are redox-sensing multifunctional enzymes, among them peroxiredoxin 6 (Prx6) can neutralize the most broadest range of hydroperoxides and play an important role in maintaining the redox homeostasis of the cell. In the present study, radioprotective and signaling regulatory effects of Prx6 were demonstrated and characterized. Intravenously administered exogenous Prx6 protects the organism of mice from the destructive action of ionizing radiation in the lethal dose range of 5-10 Gy. Dose reduction factor of 1.4 Prx6 injection reduces the severity of radiation-induced leuko- and thrombopenia in irradiated animals, also preventing the destruction of epithelial cells in the small intestine. Injecting exogenous Prx6 also as its mutated form of Prx6-C47S lacking peroxidase activity affects the expression of genes involved in antioxidant response, DNA reparation, apoptosis and inflammatory processes, in bone marrow cells both in intact animals and in those subjected to ionizing radiation. The radioprotective properties of Prx6 are based, on the one hand, on the capability for ROS neutralization, and on the other hand - on the potentiality for activation of reparation processes of the cell under oxidative stress conditions. Prx6 can be considered as a potentially perspective radioprotective agent for the reduction of risks from the damaging action of ionizing radiation on the mammalian organism.

Exogenous 8-Oxo-7,8-dihydro-2'-deoxyguanosine: Biomedical Properties, Mechanisms of Action, and Therapeutic Potential.

8-Oxo-7,8-dihydroguanine (8-oxo-G) is a key biomarker of oxidative damage to DNA in cells, and its genotoxicity is well-studied. In recent years, it has been confirmed experimentally that free 8-oxo-G and molecules containing it are not merely inert products of DNA repair or degradation, but they are actively involved in intracellular signaling. In this review, data are systematized indicating that free 8-oxo-G and oxidized (containing 8-oxo-G) extracellular DNA function in the body as mediators of stress signaling and initiate inflammatory and immune responses to maintain homeostasis under the action of external pathogens, whereas exogenous 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGuo) exhibits pronounced antiinflammatory and antioxidant properties. This review describes known action mechanisms of oxidized guanine and 8-oxo-G-containing molecules. Prospects for their use as a therapeutic target are considered, as well as a pharmaceutical agent for treatment of a wide range of diseases whose pathogenesis is significantly contributed to by inflammation and oxidative stress.

Structural modification of titanium surface by octacalcium phosphate via Pulsed Laser Deposition and chemical treatment.

In the present study, the Pulsed Laser Deposition (PLD) technique was applied to coat titanium for orthopaedic and dental implant applications. Calcium carbonate (CC) was used as starting coating material. The deposited CC films were transformed into octacalcium phosphate (OCP) by chemical treatments. The results of X-ray diffraction (XRD), Raman, Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM) studies revealed that the final OCP thin films are formed on the titanium surface. Human myofibroblasts from peripheral vessels and the primary bone marrow mesenchymal stromal cells (BMMSs) were cultured on the investigated materials. It was shown that all the investigated samples had no short-term toxic effects on cells. The rate of division of myofibroblast cells growing on the surface and saturated BMMSs concentration for the OCP coating were about two times faster than of cells growing on the CC films.

Peroxiredoxin 6 is a natural radioprotector.

After injection of 20 mg/kg peroxiredoxin 6 to male Kv:SHK mice 15 min before X-ray irradiation in the range of lethal doses (7-10 Gy), the mice remained alive for 30 days, whereas the mortality of the control animals was 100%. In the irradiated animals, peroxiredoxin 6 decreased the severity of radiation-induced leucopenia, granulocytopenia, and thrombocytopenia, increased the number of blood corpuscles, and prevented the mass death of epithelial cells and the destruction of the small intestine. Thus, peroxiredoxin 6 can be regarded as a prophylactic radioprotective agent.

[Own Chemiluminescence of Planarian Neoblasts during Regeneration].

We investigated the kinetics of the luminescence induced by reactive oxygen species in planarians during regeneration process. It was found that regeneration is accompanied with changes in the concentration of reactive oxygen species correlating with energy-intensive processes such as oxidative stress, caused by damage to cell membranes in the dissection of the planarian, phagocytosis of dying cells and mitosis of neoblasts. We showed for the first time that there is an opportunity of registering the physiological state of pluripotent stem cells at the level of the organism in vivo.

[Continuous Generation of Hydrogen Peroxide in Water Containing Very Low Concentrations of Unsymmetrical Dimethylhydrazine].

Continuous generation of hydrogen peroxide catalyzed by low concentrations of 1,1-dimethylhydrazine (heptyl)--a rocket fuel component--in air saturated water was shown by the method of enhanced chemiluminescence in the system of luminol-p-iodophenol-peroxidase. The concentration dependence and the influence of heat and light on the formation of hydrogen peroxide in the water under the influence of dimethylhydrazine at concentrations considerably lower than maximum allowable concentrations were studied, and the physical-chemical mechanism of this process was considered. It is supposed that dimethylhydrazine at ultra-low concentrations is associated with air nanobubbles and represents a long-lived complex performing catalysis of hydrogen peroxide formation under the influence of heat and light. We put forward the new concept of.toxicity of dimethylhydrazine at very low concentrations due to violation of homeostasis of reactive oxygen species formation in aqueous solutions entering the body of humans and animals.

[Radioprotectors: History, Trends and Prospects].

The search for ideal protective agents for use in a variety of radiation scenarios has continued for more than six decades. This review describes the history of the major discoveries, shows the chronology of the changes in attitudes, trends and paradigms. The readers are invited to meet with various classes of chemical compounds that have the potential to protect against acute and late effects of ionizing radiation when administered either before or after radiation exposure. The work represents characteristics of radioprotective agents such as a dose reduction factor, time of administration, tissue specificity, toxicity; the mechanisms of their action and practical applications are also described. A separate chapter considers the further development prospects and directions in this field of research.

[Effect of dilution on aggregation of nanoparticles of polycarboxylic derivative of fullerene C60].

In this work, we investigated the effect of dilution on aggregation of nanoparticles of the polycarboxylic derivative of fullerene C60. It is shown that the diminution of the concentration of PCDF-1 in aqueous medium leads to a decreased amount of aggregates of fullerene and an increased amount of single molecules. This can potentially interfere with the biological activity of a compound on one molecule basis. Addition of organic and inorganic salts to the aqueous medium with fullerene derivative leads to intense disaggregation of PCDF-1. The data obtained suggest an explanation of non-stoichiometric nature of neutralization of reactive oxygen species by derivatives of fullerenes, as well as provide new insight into the physical meaning of the work on the impact of nanoparticles at ultra-low concentrations on biological objects.

[Interaction of C60 fullerene-polyvinylpyrrolidone complex and brain Aß(1-42)-peptide in vitro].

Using a spectrophotometric method changes occurring in solution containing brain Aß(1-42)-peptide, fullerene C60, and polyvinylpyrrolidone were analyzed. Using the Bent-French method relative binding constants of fullerene C60 with Aß(1-42)-peptide and polyvinylpyrrolidone with Aß(1-42)- peptide were determined. These data suggest that Aß(1-42)-peptide interacting with the C60 fullerene-polyvinylpyrrolidone complex partially displaces polyvinylpyrrolidone and generates a new three molecular compound.

[Impact of biologically important anions on reactive oxygen species formation in water under the effect of non-ionizing physical agents].

The influence of biologically relevant anions (succinate, acetate, citrate, chloride, bicarbonate, hydroorthophosphate, dihydroorthophosphate, nitrite, nitrate) on the formation of hydrogen peroxide and hydroxyl radicals in water was studied under the effect of non-ionizing radiation: heat, laser light with a wavelength of 632.8 nm, corresponding to the maximum absorption of molecular oxygen, and electromagnetic radiation of extremely high frequencies. It has been established that various anions may both inhibit the formation of reactive oxygen species and increase it. Bicarbonate and sulfate anions included in the biological fluids' and medicinal mineral waters have significant, but opposite effects on reactive oxygen species production. Different molecular mechanisms of reactive oxygen species formation are considered under the action of the investigated physical factors involving these anions, which may influence the biological processes by signal-regulatory manner and provide a healing effect in physical therapy.

[The influence of spermine on Ca(2+)-dependent permeability transition in mitochondria and liposomes induced by palmitic and α,Ω-hexadecanedioic acids].

The effect of spermine on Ca(2+)-dependent permeability transition in mitochondria and liposomes induced by palmitic and α,Ω-hexadecanedioic acid was studied. It has been shown that spermine inhibited the cyclosporin A-insensitive mitochondrial swelling induced by palmitic acid and Ca2+ and α,Ω-hexadecanedioic acid and Ca2+. 100 µM spermine did not influence the mitochondrial respiration in state V2 and the respiration stimulated by palmitic acid, α,Ω-hexadecanedioic acid and Ca2+. Pre-incubation of liposomes with 100 µM spermine resulted in the inhibition of palmitic acid/Ca(2+)- and α,Ω-hexadecanedioic acid/Ca(2+)-induced release of the fluorescent dye sulforhodamine B from liposomes. At the same time, spermine added to fatty acids-contained membranes of liposomes stimulated Ca(2+)-dependent release of sulforhodamine B from liposomes. It was shown that an addition of spermine to liposomes resulted in a significant increase in z-potential of liposomal membranes (from -39.8 mV to -18.6 mV). A possible mechanism of spermine influence on palmitic acid/Ca(2+)- and α,Ω-hexadecanedioic acid/Ca(2+)-induced permeability transition in mitochondria and liposomes is discussed.