Mechanical alloys Mg-Me (Me: Ti, Fe, Ni, Al) & Mg-Me1-Me2(Ме1:Al, Me2: Ti, Fe, Ni) with low resistance and improved kinetics of hydrogenation/dehydrogenation for hydrogen storage applications

Changes in MgH2 decomposition kinetics were investigated in dependence on complex doping of MgH2 by Al, Ti, Ni,and Fe. Reactive mechanochemical alloying method (RMA) was applied in the temperature descending regime. It was found that addition of Al+Ni+Ti, Al+Ti, Fe+Ti (see below) and Al+Fe elements combinations led to a lower  thermal stability and, consequently, to a lowering of the temperature of hydrogen desorption onset. Whereas desorption began at temperature of 320 °C from the pure MgH2, the aditions of Al, Ni, Ti and Fe lowered the start of the desorption down to 250°C (at hydrogen pressure 0.1 MPa in the reactor). Very fast desorption kineticsprecize at 300 0C and PH 2= 0.1 MPa were observed for Mg+Me mixture in comparison with the pure Mg. Sorption capacity of investigated mechanically-alloyed composites varied from 5 to 6.5 wt. % H2. The tested materials showed a high potential as hydrogen storage alloys especially for stationary application

Fast diffusion of graphene flake on graphene layer

Diffusion of a graphene flake on a graphene layer is analyzed and a new diffusion mechanism is proposed for the system under consideration. According to this mechanism, rotational transition of the flake from commensurate to incommensurate states takes place with subsequent simultaneous rotation and translational motion until the commensurate state is reached again, and so on. The molecular dynamics simulations and analytic estimates based on ab initio and semi-empirical calculations demonstrate that the proposed diffusion mechanism is dominant at temperatures T ~ Tcom, where Tcom corresponds to the barrier for transitions of the flake between adjacent energy minima in the commensurate states. For example, for the flake consisting of ~ 40, 200 and 700 atoms the contribution of the proposed diffusion mechanism through rotation of the flake to the incommensurate states exceeds that for diffusion of the flake in the commensurate states by one-two orders of magnitude at temperatures 50 - 150 K, 200 - 600 K and 800 - 2400 K, respectively. The possibility to experimentally measure the barriers to relative motion of graphene layers based on the study of diffusion of a graphene flake is considered. The results obtained are also relevant for understanding of dynamic behavior of polycyclic aromatic molecules on graphene and should be qualitatively valid for a set of commensurate adsorbate-adsorbent systems.Comment: 33 pages, 6 figure

Interaction of the NO 3pπ (C 2Π) Rydberg state with RG (RG = Ne, Kr, and Xe): potential energy surfaces and spectroscopy

We present new potential energy surfaces for the interaction of NO(C 2Π) with each of Ne, Kr, and Xe. The potential energy surfaces have been calculated using second order Møller-Plesset perturbation theory, exploiting a procedure to converge the reference Hartree-Fock wavefunction for the excited states: the maximum overlap method. The bound rovibrational states obtained from the surfaces are used to simulate the electronic spectra and their appearance is in good agreement with available (2+1) REMPI spectra. We discuss the assignment and appearance of these spectra, comparing to that of NO-Ar

Adaptation of Students Depending on the Type of Temperament to Educational Activities in Higher School in the Conditions of Online Learning

The article examines the influence of the type of temperament on the adaptation of students to educational activities at the university in the context of online learning. The article's main aim is to study the regulatory-adaptive status of students depending on the classical and mixed types of temperament. To do so, we analyze and investigate a number of sources on this issue. For the successful adaptation of students to educational activities in the context of online learning, higher school teachers should determine what properties and characteristics of the nervous system their students have. The authors conclude that the regulatory-adaptive abilities of students to the educational process depend on the type of temperament. They are the highest among phlegmatic/sanguine students and the lowest among melancholic students

Nanotube-Based NEMS: Control vs. Thermodynamic Fluctuations

Multi-scale simulations of nanotube-based nanoelectromechanical systems (NEMS) controlled by a nonuniform electric field are performed by an example of a gigahertz oscillator. Using molecular dynamics simulations, we obtain the friction coefficients and characteristics of the thermal noise associated with the relative motion of the nanotube walls. These results are used in a phenomenological one-dimensional oscillator model. The analysis based both on this model and the Fokker-Planck equation for the oscillation energy distribution function shows how thermodynamic fluctuations restrict the possibility of controlling NEMS operation for systems of small sizes. The parameters of the force for which control of the oscillator operation is possible are determined.Comment: 40 pages, 12 figure

Long-term treatment options for postmenopausal osteoporosis: results of recent clinical studies of Denosumab

Modern medications for osteoporosis (bisphosphonates, denosumab, teriparatide) are well-tolerated drugs, which can significantly lower vertebral and non-vertebral fracture risk according to prospective and observational studies in up to 10-year period. Certain drugs (denosumab, teriparatide) are active only during the treatment period and do not prevent bone loss and fracture risk after discontinuation, while such protective effect is observed in bisphosphonates. Despite impressive success of continuous 10-year denosumab treatament of severe osteoporosis, some of the recently published data suggest that vertebral fracture incidence is increased after treatment discontinuation, along with multiple vertebral fracture incidence, especially in patients with previous fractures. Issues of osteoporosis treatment duration, sequential use of osteoporosis drugs and criteria for treatment discontinuation are now in focus of attention. European Medicines Agency (EMA) and European Calcified Tissue Society (ECTS) considered these issues in 2017. ЕМА considered fractures after denosumab discontinuation as a natural disease course and did not recommend any changes in product instruction. The main conclusion of ECTS is that the possibility of multiple fractures development after denosumab discontinuation exists, however, there is still not enough firm evidence, as well as effective countermeasures. Clinicians and patients should be aware of potential risk. Both EMA and ECTS suggest considering denosumab treatment or discontinuation after 5-year treatment period or possibly replacing with bisphosphonates. Recent data suggest that prolonged osteoporosis treatment can be done in accordance with the concept of treatment until target goal (for example, achievement of femoral T-score -2.0SD and higher). In our review, we focus on recent data concerning the issues stated above. This topic was also discussed on Russian Osteoporosis Association (ROA) expert meeting in Saint Petersburg on 24 may 2018, chaired by ROA president, professor Olga Lesnyak and Columbia University professor, J.P. Bilezikian. As a result, an Expert Council resolution was written and introduced in the article

Coulomb dissociation of N 20,21

Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N20,21 are reported. Relativistic N20,21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the N19(n,γ)N20 and N20(n,γ)N21 excitation functions and thermonuclear reaction rates have been determined. The N19(n,γ)N20 rate is up to a factor of 5 higher at

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake