Search

The specific features of the sorption activity of silver nanoparticles (AgNPs) on biodegradable polymers of natural (collagen) and artificial (polyamide 6.6) origin have been established. The ability has been demonstrated for resorbable fibers of natural origin to more actively adsorb AgNPs with sizes from 1 to 10 nm during the first hour and stronger hold them on the surface during the first day of exposure to argogel. During the first hour of incubation of these polymers in a gel composition containing AgNPs obtained by the method of cavitation-diffusion photochemical reduction, their higher sorption activity was revealed in the size range from 1 to 10 nm in relation to the polyfilament synthetic material. After 24 h of exposure, a significant increase in the fraction of small AgNPs already on collagen fibers was observed, which was also accompanied by a significantly lower (19 times) content of AgNPs with a diameter above 40 nm on the catgut.

Based on the classical quantum-mechanical approach, the physical mechanism of isotope fractionation is proposed associated with the predominance of a certain number of neutrons among nucleons and explaining the nonequilibrium accumulation of certain stable isotope shapes of biogenic elements in heterogeneous systems. The effect may be due to the interaction of the magnetic moments of atomic nuclei and valence electrons leading to a change in the distance between them, including the influence of the changed distance between atoms, on the energy of the covalent link between the pairs of atoms.

The effects of prolonged (42 day) consumption of deuterium-depleted water by rats on the functional state of their central nervous system under normal conditions and under conditions of normobaric hypercapnic hypoxia have been studied. The consumption of deuterium-depleted water both under normal conditions and after exposure to oxidative stress contributed to a significant reduction in emotional anxiety in animals. Prolonged consumption of deuterium-depleted water before experimental hypoxia (amnesic factor) helped animals to maintain their ability to learn and memory at the control level, i.e., it exerted a pronounced protective antiamnesic effect. Under normal conditions, deuterium-depleted water does not affect the learning ability of animals.

The paper studies the interaction between surgical catgut and silver nanoparticles depending on the fiber surface treatment and time of exposure (1 and 24 hours) in Ag-containing gels. After a 24-hour exposure, the maximum sorption capacity is observed on polished catgut for silver nanoparticles ranging in size from 1 to 10 nm. After this time period, the sorption capacity of silver nanoparticles on unpolished catgut occurs in Agcontaining gel within the whole size range, mainly from 1 to 5 nm, when silver nanoparticles are obtained by cavitation and diffusion photoreduction. At the same time, the incubation period of 1 hour in Argogel does not provide the potentially effective concentration of silver nanoparticles on the fiber surface.

The physical regularities that lead to isotope fractionation and to the accumulation of certain isotope forms in the intercellular and intracellular space at various levels of biological objects were studied. A new hypothesis of fractionation of stable isotopes in biological objects through the neutron effect was discussed. The following feature is noted: it is very likely that the development of isotope shock in living beings is observed mainly in the presence of covalent bonds between atoms with an uncompensated neutron. One possible explanation for this phenomenon can be associated with a change in the physical parameters of the following events: the interactions of the magnetic moments of valence electrons with the magnetic moments of atomic nuclei and the interactions of magnetic moments of atomic nuclei, which result in a change in the distance between atomic nuclei.

The level of CO2 production and the growth dynamics of the biomass of Rhodococcus erythropolis VKM Ac2017D (Russia) and the yeast strain Saccharomyces cerevisiae OenofermC2 (France) were determined in cultivation media with variously reduced (from 10 to 150 ppm) deuterium concentration. The maximum increase in the rhodococcal biomass was shown in the media with a deuterium concentration of 50 ppm or less. It was noted that the production of CO2 as an integral indicator of the biological activity of cells is more pronounced in Rhodococcus compared to the yeast. With generally similar dynamics of CO2 emission curves, prokaryotes showed broader temporal dynamics of its production.

—It is established that a medium with a reduced content of deuterium has no effect on the secondary structure of horseradish peroxidase and bovine serum albumin and caused no conformational changes in the structures of these proteins. The placement of these proteins in a buffer solution prepared based on deuterium-depleted water led to a decrease in the intensity of intrinsic tryptophan fluorescence, while the circular dichroism spectra remained virtually unchanged. A decrease in the content of deuterium in the reaction medium led to a decrease in the activity of the peroxidase oxidation reaction of o-dianisidine and luminal with hydrogen peroxide.

We studied the effect of a low-frequency (LF) electromagnetic field (EMF) on the state of the antioxidant system of Wistar rats in vivo. It was found that changes in activity of antioxidant enzymes and H

In this paper, on the basis of the classical quantum-mechanical approach, an explanation is considered of the physical mechanism of isotope fractionation associated with the predominance of a certain number of neutrons among nucleons and explaining the nonequilibrium accumulation of certain forms of stable isotopes of biogenic elements in heterogeneous systems. The reasons for the detected neutron effect can be: the interaction of the magnetic moments of atomic nuclei and valence electrons, leading to a change in the distance between them, including the effect of the changed distance between atoms on the energy of the covalent bond between the resonant pairs of atoms.

The absorption activity of silver nanoparticles (AgNPs) on the surface of fibers of natural and artificial origin is estimated. In addition, it is determined that the sorption activity of natural or artificial fibers with respect to silver nanoparticles depends on their size, fabrication method, and properties of the gelling agent. It is found that the highest absorption of silver nanoparticles is observed when using natural silk fibers, which possess a significantly higher activity as compared with an artificial fiber (fluoroex).

The aggregate stability of silver nanoparticles (Ag – NPs) in a gel composition is estimated. It is established that during long-term storage (for 3 years), a decrease in the number of nanoparticles with sizes of 1–5 and 5–10 nm and a significant increase in the number of nanoparticles with sizes of 10–15 nm are observed. At the same time, the fraction of silver nanoparticles with sizes greater than 30 nm is less than 5%.

The sensitivity of DNA to electromagnetic radiation in different ranges differs depending on various factors. The aim of this study was to examine the molecular dynamics of DNA under the influence of external periodic influences with different frequencies. In the present paper, within the framework of a mechanical model without simplifications, we investigated the effect of various frequencies of external periodic action in the range from 1011 s−1 to 108 s−1 on the dynamics of a DNA molecule. It was shown that under the influence of an external periodic force, a DNA molecule can perform oscillatory movements with a specific frequency characteristic of this molecule, which differs from the frequency of the external influence ω. It was found that the frequency of such specific vibrations of a DNA molecule depends on the sequence of nucleotides. Using the developed mathematical model describing the rotational motion of the nitrogenous bases around the sugar–phosphate chain, it is possible to calculate the frequency and amplitude of the oscillations of an individual DNA area. Such calculations can find application in the field of molecular nanotechnology.

Objective: To evaluate the effectiveness of a new treatment method in healing superficial infected wounds compared with surgical debridement with chlorhexidine solution. Method: In this animal model, two wounds were created on the back of 10 male adult rabbits. Wounds treated by Method 1 were debrided using 0.02% chlorhexidine aqueous solution and an antibiotic topical ointment. Wounds treated by Method 2 wounds were treated using a newly developed device which enabled visual monitoring of the wound as it was treated with various pharmacological solutions (including antiseptic, antiseptic oxidant and an osmotically active agent) specifically formulated for each wound healing stage. Wound area size (using digital planimetry) and time taken to clean the wound were recorded, and biopsies were taken, at the beginning of the study and at various timepoints throughout. Result: It was observed that both wound cleaning and wound healing were accelerated by treatment with method 2 compared with method 1 (by 43.8% and 36.7%, respectively). There were also a significantly smaller number of complications in these wounds [p=0.0044] due to the positive ratios of neutrophils and fibroblasts in the wound cavities (from the third to the fourteenth day after wound modelling). Conclusion: Wounds treated with the new device in method 2 had a shorter wound healing time than wounds treated with a traditional method. The automated influx–outflow of solutions removed any fragments of necrotic tissue from the wound surface. Wounds were able to be monitored without the need to remove dressings. The transparent, airtight film, which allowed for wound monitoring without the need to remove dressings, meant that suturing was not required. This resulted in no complications in the wounds treated by this new method.

The deuterium content modification in an organism has a neuroprotective effect during the hypoxia model, affecting anxiety, memory and stress resistance. The aim of this work was to elucidate the possible mechanisms of the medium D/H composition modification on nerve cells. We studied the effect of an incubation medium with a 50 ppm deuterium content compared to a medium with 150 ppm on: (1) the activity of Wistar rats’ hippocampus CA1 field neurons, (2) the level of cultured cerebellar neuron death during glucose deprivation and temperature stress, (3) mitochondrial membrane potential (MMP) and the generation of reactive oxygen species in cultures of cerebellar neurons. The results of the analysis showed that the incubation of hippocampal sections in a medium with a 50 ppm deuterium reduced the amplitude of the pop-spike. The restoration of neuron activity was observed when sections were returned to the incubation medium with a 150 ppm deuterium content. An environment with a 50 ppm deuterium did not significantly affect the level of reactive oxygen species in neuron cultures, while MMP decreased by 16–20%. In experiments with glucose deprivation and temperature stress, the medium with 50 ppm increased the death of neurons. Thus, a short exposure of nerve cells in the medium with 50 ppm deuterium acts as an additional stressful factor, which is possibly associated with the violation of the cell energy balance. The decrease in the mitochondrial membrane potential, which is known to be associated with ATP synthesis, indicates that this effect may be associated with the cell energy imbalance. The decrease in the activity of the CA1 field hippocampal neurons may reflect reversible adaptive changes in the operation of fast-reacting ion channels.

In the present study, the effect of 2H/1H isotopic exchange in hydrogen bonds between nitrogenous base pairs on occurrence and open states zones dynamics is investigated. These processes are studied using mathematical modeling, taking into account the number of open states between base pairs. The calculations of the probability of occurrence of open states in different parts of the gene were done depending on the localization of the deuterium atom. The mathematical modeling study demonstrated significant inequality (dependent on single 2H/1H replacement in DNA) among three parts of the gene similar in length of the frequency of occurrence of the open states. In this paper, the new convenient approach of the analysis of the abnormal frequency of open states in different parts of the gene encoding interferon alpha 17 was presented, which took into account both rising and decreasing of them that allowed to make a prediction of the functional instability of the specific DNA regions. One advantage of the new algorithm is diminishing the number of both false positive and false negative results in data filtered by this approach compared to the pure fractile methods, such as deciles or quartiles.

The method of modifying suture material with silver nanoparticles was tested. The paper presents the results nanoparticle sorption on the surface of different types of polymer fibers. The expediency of processing suture threads for intraoperative prophylaxis of purulent-septic complications in surgery is shown.

—The study evaluated the adsorption of Ag-containing solutions and gel compositions on modern natural and artificial fibers, as well as polyfilament threads with different coatings. It was determined that natural fibers are characterized by the highest adsorption. The developed gel composition based on silver nanoparticles also demonstrates high sorption on suture thread material combined with a chemically inert coating (e.g., silicone). The distribution of silver nanoparticles on Polyester suture thread material was accompanied by a significant predominance (up to 76%) of particles 1 to 5 nm in size. It has been established that silver nanoparticles as part of the Argogel preparation can be efficiently adsorbed by various suture thread materials, primarily when exposed to Sabfil (up to 36%) and Dexon (up to 38%) threads. After 1 h of exposure to a synthesized Ag gel with silver nanoparticles obtained by cavitation-diffusion photochemical reduction, the nanoparticles are significantly (up to 14%) sorbed on the surface of the suture thread material, including Catgut and Dexon, with decreased subsequent aggregation of sorbed nanoparticles. It was determined that although the components of the suture thread material do not deactivate silver ions, it remains highly probable that they will bind to various ions, primarily forming insoluble silver chlorides and phosphates in the wound fluid.

The aim was to investigate prooxidant-antioxidant system in the blood and brain homogenates functional activity in rats with acute hypoxia model with different deuterium/protium (D/H) ratios in drinking diet. Studies have shown that consuming DDW (–665 ‰) within 8 weeks lead to deuterium concentration decrease in blood plasma at 317 ‰ and brain at 209 ‰ of rats, in comparison to control group, consuming natural water. DDW consumption before hypoxia modeling in rats improves antioxidant defense enzymes (catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase) activity in the blood, increasing its antioxidant potential by 20 %, while free radical oxidation intensity in plasma and biomolecules peroxide modification rate in erythrocytes. Also, in brain tissues consuming DDW, there were no abnormalities in catalase, superoxide dismutase activity, and it was noted increase (by 71 %) in reduced thiol-containing compounds concentration, which reduces nerve hypoxi? cell damage risk. Neuroprotective effect presence is confirmed by higher (by 32 %) antioxidant activity markers of lyophilized brain tissues, and by free radical oxidation lower intensity (by 13 %) and biomolecules oxidative modification rate (by 16 %) in these lyophilized tissues. Thus, the advisability of using DDW neuroprotective effects in cerebral circulation disturbance in experimental and clinical practice.

The results of our study of the size, optical properties, and aggregate stability of silver nanoparticles in aqueous solutions 1, 2, and 12 months after their synthesis are reported. It has been shown that nanoparticles synthesized using a combined application of physical factors, such as ultraviolet radiation, ultrasound, and uniform mixing (providing conditions of isolation from the atmospheric air) are smaller in size (from 1 to 10 nm) and have more homogenous distribution of the diameter of nanoparticles. A lower aggregation has been noted compared with particles prepared without observing the synthesis algorithm that was developed and conditions given above. The results of studying antimicrobial antiseptic properties based on a colloidal nanosilver solution prepared using the technology of diffusion-cavitation photochemical reduction of silver nitrate are also reported. A high antimicrobial activity of the resulting colloidal solution with silver nanoparticles against clinical isolates of P. aeruginosa, A. baumanii, and E. coli has been demonstrated as compared with the original silver nitrate and the ligand (polyvinylpyrrolidone) used in the synthesis of the colloid at the same concentration. At a concentration of 10 μg/mL, a colloidal solution with silver nanoparticles has been found to possess bactericidal activity against two isolates of P. aeruginosa, three isolates of A. baumanii, and five isolates of E. coli. At a concentration of 1 μg/mL, the colloidal solution of silver nanoparticles has possessed only bacteriostatic activity against all isolates of the bacteria. The minimum bacteriostatic inhibitory concentration of nanosilver has determined to be 3 μg/mL.

The paper presents the results of research and development of concentrated type p—i—n-diodes switches providing the switching time at the level of a few nanoseconds. To increase lock losses of (~40 dB) the authors use a cascade connection of diodes into waveguide and microstrip transmission line of q = p/2 electric length. Investigation results of creation of switching devices using longitudinally and transversely-distributed p—i—n-structures in the shortwave part of the millimeter wavelength range (f = 300 GHz) are presented. When developing switching devices intended to control the level of microwave power in the millimeter wavelength range, a number of special features arise limiting the achievement of optimal parameters. The dimensions of the metal ceramic packaged p—i—n-diodes and the mounting elements of semiconductor structures become comparable with the wavelength. As a result, package cannot be considered in the calculations and in the design as the capacity of the concentrated type. In our case the diode package is considered in the form of radial line which is able to transform the input impedance of the transmission line to the terminals of the diode structures, and realize high-impedance state (parallel resonance) in the device circuit in the mode of microwave power transmission. Engineering calculations for the given parameters of the silicon mesostructures showed the possibility of creating high-speed devices for switching microwave power with good characteristics. For diode assembling industrial clockwork ruby jewels with high quality of surface finish, strength and appropriate dimensions are applied as dielectric bushings. Suffice it to say that in the frequency range of 150 GHz, we used the bushings with dimensions of external diameter D = 0.4 mm and a height of h = 0.15 mm. The switches created provide transient units of nanoseconds, isolation more than 40 dB at relative frequency bandwidth of 30-40%. Evaluating progress in the development of millimeter wavelength devices, it should be noted that at frequencies greater than 200 GHz, the application of the concentrated type diodes is problematic. In this range it would seem to be promising to use bulk semiconductors. In this case surface-oriented p—i—n-structures can be applied as unified elements of the control devices in the shortwave part of the millimeter range, as well as in quasi-optical transmission lines.

Transmitting devices for small radars in the millimeter wavelength range with high resolution on range and noise immunity. The work presents the results of research and development of compact pulse oscillators with digital frequency switching from pulse to pulse. The oscillator consists of a frequency synthesizer and a synchronized amplifier on the IMPATT diode. Reference oscillator of synthesizer is synchronized by crystal oscillator with digital PLL system and contains a frequency multiplier and an amplifier operating in pulse mode. Small-sized frequency synthesizer of 8 mm wave lengths provides an output power of ~1.2 W per pulse with a frequency stability of no worse than 2•10–6. Radiation frequency is controlled by three-digit binary code in OOL levels. Synchronized amplifier made on IMPATT diodes provides microwave power up to 20 W in oscillator output with microwave pulse duration of 100—300 ns in an operating band. The oscillator can be used as a driving source for the synchronization of semiconductor and electro-vacuum devices of pulsed mode, and also as a transmitting device for small-sized radar of millimeter wave range.

The research concerning the effect of the remedies with the different antioxidant mechanisms on the indices of carbohydrate and lipid metabolism as well as the thiol link of the antioxidant system and the functional detoxication system in modeling conditions of the decompensated alloxan diabetes mellitus have been presented. The research was performed on 105 white nonlinear male-rats with initial body weight (b.w.) 200-230 g, divided into seven groups. Group 1 has consisted of the intact animals. Group 2 (the comparison group) has consisted of the animals suffering from the severe alloxan diabetes mellitus (intraperitoneal administration of alloxan monohydrate at 10 mg/100 g b.w. three times, with an interval of one day, against fasting) without correction. In groups 3-7 diabetes mellitus has also been modeled. The animals of group 3 were fed by the diet with the supplement containing the antioxidant complex with high content of carotenoid substances (1 mg lutein per day, orally for a month before simulations of diabetes mellitus and for a month after). The animals of group 4 have been given the sodium dichloroacetate (15 mg/100g bw) with drinking water for the month before and a month after the modeling of diabetes. The animals of group 5 have been injected with the reduced glutathione (15 mg/100 g of b.w.) daily one week prior to administration of alloxan and until the end of the experiment, the animals of group 6 have been injected with the quercithin (10 mg/100 g of b.w.) and the rats of group 7 have been given the water with the reduced content of deuterium (91 mg/l) instead of the usual drinking water. The development of experimental alloxan diabetes mellitus in rats has been accompanied by the increase in blood plasma of glucose concentration by 6.9-fold, cholesterol and lipoproteins of low density by 66 and 100% respectively. The compensatory activity increase of the antiradical protective enzymes (glutathione peroxidase and glutathione reductase) as well as the concentration decrease of reduced glutathione in erythrocytes by 11% have been revealed. According to the data concerning the level of the molecules with medium and low mass in blood plasma as well as in erythrocytes, the evident endogenous intoxication has taken place. The performed researches have proved the presence of the significant hypoglycemic effect of the usage of sodium dichloroacetate, of the water with the reduced content of deuterium and of quercithin - the glucose concentration in these groups was lower than in the comparison group by 36, 33 and 47% respectively. In the same groups as well as in the group of rats injected with glutathione the hypolipidemic effect of various manifestation degree has been detected, the most evident in animals from group 7 in which all the indices except triglycerides haven't differed from indices of the control group. The usage of various corrective methods has also assisted the adequate functioning of the antioxidant system that has been proved by the normalization of glutathione content except of groups 3 and 6 in which its concentration was lower than the control indices by 25 and 12% respectively. Endogenous intoxication has been significantly lower in groups 4, 5 and 7 in which the level of molecular of medium and low mass in blood plasma was normal and only in erythrocyte mass was increased by 49-74% than in the control group. Thus, the data obtained prove the usage availability of the antioxidant remedies in the complex therapy in patients suffering from the diabetes mellitus. The most interesting is the usage of antioxidants with the indirect mechanism of action, i.e. the water with the reduced content of deuterium and sodium dichloroacetate. Quercithin and the reduced glutathione deserve attention as well, and considering the hypoglycemic effect of the first one and the metabolic effects of glutathione aimed at the functioning maintenance of the non-specific organism resistance, the possibility of the combined usage of both antioxidants should be taken into account.

The dynamics of the pro-oxidant/antioxidant system of rabbits was studied at the local (in exudate) and systemic (blood) levels during therapy of purulent wounds in liquid medium with the use of a programmed device and the efficiency of the proposed technological method was compared with that of classical methods for the treatment of these wounds. More rapid recovery of the indicators of the pro-oxidant/antioxidant system to physiological values in the postoperative period was observed after treatment by the proposed method (7 days vs. 10 days after standard treatment), these results attest to strengthening of the adaptation potential in laboratory animals. The intensity of free radical oxidation in the exudate decreased by 26.6% in animals treated by the technological method. These data indicated acceleration of the regenerative processes at the local level.

Present-day technology allows manufacturing of GaAs/AlGaAs heterostructures with layers width down to a nanometer. Time of electron tunneling through AlGaAs potential barrier with such width and height of a few tenths of electron volt is less than a picosecond. It makes possible to create microwave diode on base of the single-barrier nanostructure with electron tunnel injection through AlGaAs potential barrier and electron drift in GaAs transit layer with comparable time delays of electron tunneling and transit. Microwave impedance of the diode we study in framework of small-signal theory but with considering electron injection delay along with transit delay as for resonant-tunneling diode.

A model of small-signal impedance of semiconductor transit-time diode with injection time of electron negligible less than its transit time had been developed by Sze [1]. Modification of the model with consideration of injection delay has been applied on studying of semiconductor [2] and vacuum [3] resonant-tunneling diodes impedance. We apply the modification to investigate impedance of a diode on AlGaN micro-cathode with electron field emission and transit in vacuum layer with comparable emission and transit time delays.

The article concerns the results of analysis of frequency characteristics of fast amplitude switches of inverse type in the millimeter wave range with the use of the silicon diode p+-n-n+-structures mounted in a dielectric package. The dielectric package is considered in the form of the radial line with the distributed parameters which ensure transforming of input impedance of a transmission line to the diode structure switching terminals in order to realize a parallel resonance condition in a switch circuit in microwave power transmission mode. Requirements are determined for the diode parameters and construction providing realization of the optimum operating mode of the switch in a working band.