The search for natural biologically active substances having a neuroprotective effect against cerebral ischemia-reperfusion injury is one of the major priorities of modern neuroscience and medicine. ...Intranasal insulin (INI) exerts a pronounced restorative effect on various neurodegenerative diseases, but the mechanisms of its action and its therapeutic effects in cerebral ischemia have not been well studied, including in type 2 diabetes mellitus (DM2) which increases the risk of cerebrovascular dysfunction. The aim of the work was to study the effect of INI on metabolic parameters and inflammatory factors in male Wistar rats with DM2, exposed to cerebral ischemia, as compared to nondiabetic animals. DM2 was induced by a combination of high-fat diet and low-dose (25 mg/kg) streptozotocin administration. Cerebral ischemia was studied in a rat model of global forebrain ischemia-reperfusion (IR) injury induced by occlusion of both common carotid arteries, followed by a 7-day reperfusion. Two h after the end of ischemic exposure, the rats were treated with INI at a dose of 0.5 or 2.0 IU/rat, after which the drug was administered at the same dose, once a day, for the following 7 days. INI was found to prevent body weight loss in both nondiabetic and DM2 IR-exposed rats, while elevating plasma total cholesterol levels and epididymal fat fraction in IR-exposed nondiabetic animals only. In IR-exposed DM2 rats, INI (at both doses used) reduced postprandial plasma levels of glucose and insulin, indicative of improved glucose tolerance, as well as plasma levels of inflammatory factors, C-reactive protein (at a dose of 0.5 IU/rat/day), and tumor necrosis factor-α (at a dose of 2 IU/rat/day), indicative of its anti-inflammatory potential. Thus, a post-IR course treatment with INI improves metabolic parameters and abates inflammatory responses in DM2 rats, which may be in high demand when correcting ischemic stroke in patients with DM2.
Modern and future nanoelectronic and nanophotonic applications require precise control of the size, shape and density of III-V quantum dots in order to predefine the characteristics of devices based ...on them. In this paper, we propose a new approach to control the size of nanostructures formed by droplet epitaxy. We reveal that it is possible to reduce the droplet volume independently of the growth temperature and deposition amount by exposing droplets to ultra-low group-V flux. We carry out a thorough study of the effect of arsenic pressure on the droplet characteristics and demonstrate that indium droplets with a large initial size (>100 nm) and a low surface density (<10
cm
) are able to shrink to dimensions appropriate for quantum dot applications. Small droplets are found to be unstable and difficult to control, while larger droplets are more resistive to arsenic flux and can be reduced to stable, small-sized nanostructures (~30 nm). We demonstrate the growth conditions under which droplets transform into dots, ring and holes and describe a mechanism of this transformation depending on the ultra-low arsenic flux. Thus, we observe phenomena which significantly expand the capabilities of droplet epitaxy.
The article deals with the issues of improving the efficiency of production and logistics systems (PLS) of machine-building enterprises through the joint use of MES/APS systems and simulation systems ...for verification of production plans and decision support. The possibility of using the PlantTwin simulation system on the example of a small machine- building enterprise is considered. Simulation of the operation of the enterprise’s PLS when performing a given production program is performed. Based on the results of simulation modeling, a number of organizational and technological proposals and recommendations for improving the efficiency of the enterprise’s PLS were formed. The proposed solutions were verified by making changes to the simulation scenario and obtaining new results showing their effectiveness.
Abstract
In this work, experimental studies of the influence of the arsenic molecular form (di-or tetramers) and substrate temperature on the crystallization of In/GaAs droplet nanostructures during ...droplet epitaxy have been carried out. We have shown the critical influence of the temperature and arsenic molecular form on the reproducibility of the characteristics of an array of self-organizing InAs nanostructures during crystallization. We also showed that a decrease in the initial In droplet size has a positive effect on the reproducibility of the parameters of the InAs nanostructures arrays. Our work also showed important role of substrate temperature at the crystallization stage.
The paper presents the results of an experimental study of the effect of Al content in the epitaxial surface layer on the growth of In nanostructures formed by droplet epitaxy. We have shown that an ...increase in the Al content leads to a decrease in the droplet density and an increase in their size. We also showed that the influence of the Al content on the droplet characteristics is much less significant than that in case of the Stranski-Krastanov growth. The increase in the critical thickness of droplet formation on Al-containing surfaces when the temperature decreases is not significant. It allows us to control quantum dot emission wavelength almost independently of their geometric characteristics.
We present the results of theoretical studies of the self-organization processes of nanoscale metal In droplets on GaAs(001) substrates with artificial structural heterogeneities of various types - ...with a rectangular, trapezoidal, and triangular shapes. The study showed that to improve the accuracy of nanostructure positioning and homogeneity, it is necessary to use patterns with triangular grooves. In order to ensure the full groove filling by the material and to suppress the undesirable structure formation outside modified areas, it is necessary to provide sufficient diffusion length of adatoms taking into account the peculiarities of the patterned surface morphology.
Abstract
In this paper, we present the results of kinetic Monte Carlo study of the In/GaAs growth by droplet epitaxy in conditions of non-stationary vapor supersaturation. These conditions allow ...achievement of the independent control of size and surface density of nanostructures. The material redistribution is realized on the surface when indium deposition is interrupted and leads to a decrease in the critical thickness of droplet formation. An average droplet size increases with increase in interruption time whereas the surface density decreases. However, additional nucleation within the wetting layer can also be observed during the growth interruptions, which makes it possible to increase the surface density of droplets.
Abstract
In this work, we studied the effect of the deposition thickness, growth rate, arsenic flux, and implantation dose on the morphology of the GaAs nanostructures grown on modified Si areas. It ...is shown that an increase in the growth rate at the initial stages of the growth process leads to the transition of the growth regime from layered-like to one-dimensional with the formation of nanowires. Studies of the effect of As4 pressure have shown that a change in the equivalent As4 flux in the range of 3.7 - 5.0 ML/s does not lead to any significant change in the structure of the GaAs layer in the modified areas. An increase in the implantation dose during processing with a focused ion beam led to disordering of the directions of the grown nanowires due to the degradation of the substrate crystal structure.
Abstract
In this paper, we present the results of an experimental study of the influence of the ultra-low arsenic flux on the parameters of In nanodroplets obtained by droplet epitaxy on the GaAs ...substrate. We demonstrate that the arsenic flux can be used to alter the size of droplets without changing their surface density. An increase in the arsenic flux leads to a reduction of the nanostructure size or their complete decay. However, we demonstrate that certain growth conditions allow providing saturation of the size of nanostructures (∼30 nm) which ensures good reproducibility of the process. The mechanism of ring and hole formation at various arsenic fluxes is also discussed.
Abstract
The article reflects the results of studies carried out in the period from 2017 to 2019 in the dry steppe zone of the Russian Federation to assess the resistance of sunflower and the ...effectiveness of weed control when using oxyfluorfen before sowing and during the growing season of the crop in various doses and tank mixtures. The dynamics of weediness of sunflower crops according to the growing season of the crop and the timing of the use of herbicides and their tank mixtures has been established. The data of accounting for the increase in leaf area, as well as determining the photosynthetic potential of crops and the net productivity of photosynthesis when using herbicides before sowing and during the growing season of sunflower in different doses and tank mixtures are presented. Indicators of sunflower productivity and quality of seeds were determined for the studied schemes of herbicide application. The data obtained from the economic and energy assessment of the effectiveness of the use of oxyfluorfen on sunflower in terms of crop vegetation are analyzed.
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