Ab-initio study of cation-rich InP(001) and GaP(001) surface reconstructions and iodine adsorption

Atomic and electronic structures for a number of InP and GaP (001) surface geometries were studied within the density functional theory (DFT) in order to reexamine the energy stability of surface reconstructions in the cation-rich limit. It is shown that in both cases the mixed dimer (2×4) reconstruction is the energetically favored in the cation rich limit. The ζ(4×2) reconstruction has the lowest surface energy among considered (4×2) surface structures. Comparative theoretical study of iodine adsorption on the semiconductor surface with ζ(4×2) and mixed dimer (2×4) structures was performed. It was shown that iodine prefers to be bonded with dimerized cation atoms irrespective on the surface reconstruction

The impurity influence on the formation of oxide layers on TiAL surface

Using ab initio approach the segregation of 4d impurities to low index TiAl surfaces was studied. The site preference for all considered impurities was determined. We demonstrate that Y, Zr, Nb и Mo prefer to occupy the Ti-sublattice whereas other elements are located mainly on the Al-sublattice in case of their low concentration. The influence of impurities on oxygen adsorption on the stoichiometric γ-TiAl(100) surface is investigated. It is shown that the 4d impurities substituting for Ti result in decrease of oxygen adsorption energy whereas it increases if transition metal impurities occupy the Al-sublattice. The effect of some elements of V and VI groups on the adhesion at interfaces such as TiAl(001)Al/TiO2(001), TiAl(001)Ti/TiO2(001), TiAl(100)/TiO2(001), TiAl(110)Al/TiO2(100)O and TiAl(110)Ti/TiO2(100)O in dependence on their location in interfacial layers was also studied. Finally, we demonstrate that the 4d alloying elements with number of electrons from 2 to 5 lead to decrease of the relative stability of Al2O3 to TiO2 and to increase of the formation energy of O vacancy in TiO2. The latter is beneficial to the oxidation resistance of TiAl alloys

Motor Cortex Hyperexcitability, Neuroplasticity, and Degeneration in Amyotrophic Lateral Sclerosis

Neuronal hyperexcitability is a well-known phenomenon in amyotrophic lateral sclerosis and other neurodegenerative diseases. The use of transcranial magnetic stimulation in clinical and research practice has recently made it possible to detect motor cortex hyperexcitability under clinical conditions. Despite numerous studies, the mechanisms and sequelae of the development of hyperexcitability still have not been completely elucidated. In this chapter, we discuss the possibilities for detecting motor cortex hyperexcitability in patients with amyotrophic lateral sclerosis using transcranial magnetic stimulation. The potential relationship between hyperexcitability and neuronal degeneration or neuroplasticity processes is discussed using the data obtained by navigated transcranial magnetic stimulation and neuroimaging data, as well as the data of experimental studies

The peculiarities of halogens adsorption on A3B5(001) surface

Theoretical study of the F, Cl, Br, I adsorption on GaAs(001) surface is presented. The most stable configurations of halogens on Ga-rich ζ-(4×2) reconstruction are determined with increasing of adatoms concentration. The bonds weakening is found more significant for the F and Cl atoms which can induce stationary etching whereas I-induced changes in Ga-As binding energy is not sizable and its adsorption lead to the surface passivation

Mathematical Modeling of a Solar Arrays Deploying Process at Ground Tests

This paper focuses on the creating of a mathematical model of a solar array deploying process during ground tests. Lagrange equation was used to obtain the math model. The distinctive feature of this mathematical model is the possibility of taking into account the gravity compensation system influence on the construction in the deploying process and the aerodynamic resistance during ground tests

Skeletal Recovery Following Long-Duration Spaceflight Missions as Determined by Preflight and Postflight DXA Scans of 45 Crew Members

Introduction: The loss of bone mineral in astronauts during spaceflight has been investigated throughout the more than 40 years of bone research in space. Consequently, it is a medical requirement at NASA that changes in bone mass be monitored in crew members by measurements of bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA). This report is the first to evaluate medical data to address the recovery of bone mineral that is lost during spaceflight. Methods: DXA scans are performed before and after flight in astronauts who serve on long-duration missions (4-6 months) to ensure that medical standards for flight certification are met, to evaluate the effects of spaceflight and to monitor the restoration to preflight BMD status after return to Earth. Through cooperative agreements with the Russian Space Agency, the Bone and Mineral Lab at NASA Johnson Space Center (Houston, TX), also had access to BMD data from cosmonauts who had flown on long-duration missions yielding data from a total of 45 individual crew members. Changes in BMD (between 56 different sets of pre- and postflight measurements) were plotted as a function of time (days after landing); plotted data were fitted to an exponential mathematical model that determined i) BMD change at day 0 after landing and ii) the number of days after which 50% of the lost bone was recovered ("Recovery Half-Life"). These fits were performed for BMD of the lumbar spine, trochanter, pelvis, femoral neck and calcaneus. Results: In sum, averaged losses of bone mineral after spaceflight ranged between 2-9% for sites in the axial and appendicular skeleton. The fitted postflight BMD values predicted a 50% recovery of bone loss for all sites within 9 months

Using machine learning to study the population life quality: methodological aspects

Assessment of the population life quality is an important and relevant sociological task. Machine learning as a classification tool of social network users’ digital traces makes it possible to create a base to calculate subjective life quality index. The article consistently reviews all stages of the machine learning algorithms application to assess the life quality of the population of the regions of the Russian Federation and the issues of improving neural network accuracy. To train the neural network the authors formed a set of marked-up data extracted from regional communities of the social network “VKontakte”. Various approaches to text vectorisation, publicly available neural network models pre-trained on large Russian-language text corpora, as well as metrics for evaluating the algorithms results were analysed. Computational experiments with different algorithms were carried out, according to the results of which the Rubert-tiny algorithm was selected due to its high learning and classification rate. During the model parameters adjustment, the accuracy of f1-macro 0.545 was achieved. Computational experiments were carried out using Python scripts.Typical errors that a neural network makes in the process of automatic content classification were considered. The results of the study can be used to calculate the online activity index in the VKontakte social network of users from various Russian regions, on the basis of which the subjective life quality index will be calculated in the future. Improving the neural network accuracy will make it possible to obtain more reliable data for assessing the life quality in Russian regions based on users’ digital traces

Ferromagnetic HfO2/Si/GaAs interface for spin-polarimetry applications

In this letter, we present electrical and magnetic characteristics of HfO2-based metal-oxide-semiconductor capacitors (MOSCAPs), along with the effect of pseudomorphic Si as a passivating interlayer on GaAs(001) grown by molecular beam epitaxy. Ultrathin HfO2 high-k gate dielectric films (3–15 nm) have been grown on Si/GaAs(001) structures through evaporation of a Hf/HfO2 target in NO2 gas. The lowest interface states density Dit at Au/HfO2/Si/GaAs(001) MOS-structures were obtained in the range of (6−13)×101

N-acetylcysteine relieves neurologic signs of acute ethanol hangover in rats

Orally administered NAC before acute ethanol intoxication led to a decrease in the severity of neurological deficiency in rats and reduced the amnesic effect of ethanol. This could be due to an improvement of ethanol metabolism and a decrease in the severity of disorders associated with oxidative stress and liver dysfunctio