bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevalence of sleep disorders in Parkinson’s disease patients in Ethiopia
Authors: Melka Dereje , Tafesse Abenet , Bower James H. , Assefa Demeke
Published: March 2019

Background: Non motor symptoms (NMS) of Parkinson’s disease (PD) are common and can be more disabling than motor symptoms.Sleep disorders can be seen in up to 98% of patients with Parkinson disease. Poor sleep quality has been associated with poverty and race, and yet there has been no prior report on sleep disorders in those with PD living in sub Saharan Africa. We wished to document the prevalence of sleep disorders in PD patients in Ethiopia. Methods: We conducted a cross-sectional point prevalence study from July 1 to October 30, 2015 of all patients attending the neurology outpatient department in Tikur Anbessa and Zewuditu Memorial Hospitals, Addis Ababa, Ethiopia. Demographic data, clinical history and physical examination findings were collected from participants using a structured questionnaire. We used the Parkinson’s disease sleep scale version two (PDSS-2) and Epworth Sleepiness Scale (ESS) to assess the sleep symptoms. Results: Of the 155 patients surveyed, all patients reported some sleep problem. Over 43.9% of patients had a PDSS score > 18. Presence of previous history of sleep disturbance before PD motor symptoms (OR 3.54; 95% CI 1.61-7.76, p=0.001) and unemployment (OR 2.27; 95% CI 1.07-4.79, p=0.023) associated with a high PDSS-2 score. The median score of ESS was 9 (IQR = 5-12), with 77/155 (49.7%) of the patients having possible or definite excessive daytime somnolence. Conclusions: In Ethiopian PD patients, the prevalence of those with severe sleep disorders is the highest reported to date. The prevalence of possible/definite EDS is amongst the highest in the world. Further investigation into whether poverty or race explains this finding is needed.
Effects of Prophylactic Swallowing Exercises on Dysphagia and Quality of Life in Patients with Head and Neck Cancer Receiving (Chemo) Radiotherapy
Authors: Guillen-Sola Anna , Bofill-Soler Neus , Marco Ester , Pera-Cegarra Oscar , Foro Palmira
Published: March 2019

Background: Squamous carcinoma of the head and neck (HNC) has a high incidence in our context. Although therapeutic radiotherapy protocols try to preserve swallowing function and essential speech organs, dysphagia is a frequent symptom in the acute and long-term phases, due to the toxic effects of therapies needed to confront the illness. Some studies have shown prophylactic oropharyngeal exercises to be quite useful in improving swallowing function after completion of chemo-radiation therapy (CRT) protocols; others have focused on their use to prevent or minimize post-CRT swallowing dysfunction. Patients’ quality of life deteriorates greatly during CRT, with a peak of maximum intensity during the days immediately after finishing CRT treatment. Afterwards, function gradually improves, although scope or timeframe remains undetermined. Available evidence suggests that exercise therapy prior to oncological treatment could potentially improve deglutition and quality of life; however, a randomized study is needed to confirm this observation.
Design/Methods: The Redyor singe-blind randomized clinical trial is designed to compare the effect of prophylactic oropharyngeal exercises on quality of life, dysphagia, and sustainability to the length of rehabilitative treatment. At enrollment, participants will be randomly assigned to one of two treatment groups. Both groups follow the protocol described here, although one group begins the training 2 weeks before initiating CRT and the other group just after finishing the therapy. Both groups will complete standard swallow therapy for training submental muscles involved and 3 sets of 5 inspiratory and expiratory repetitions using the Orygen Dual® valve, with a progressive weekly increase in workload.
Discussion: This ongoing clinical trial, registered in 2016, is based on the hypothesis that undergoing a pre-radiotherapy rehabilitation (pre-habilitation) program will have greater benefits (less decrease in quality of life, less delay in swallowing parameters, and less severe dysphagia) compared to post-CRT rehabilitation. The primary objective is to assess dysphagia severity and evaluate quality of life due to swallowing dysfunction in HNC patients. Secondary objectives are to assess the correlation between a clinical variable and instrumental parameters in this period
Statistical analysis plan for early mobilisation by head-up tilt with stepping versus standard care after severe traumatic brain injury – a randomised clinical feasibility trial
Authors: Riberholt Christian Gunge , Gluud Christian , Jakobsen Janus Christian , Mehlsen Jesper , Møller Kirsten
Published: March 2019

Background: Early mobilisation on a tilt table with stepping versus standard care may be beneficial for patients with severe brain injury, but data from randomised clinical trials are lacking.

Methods: This statistical analysis plan describes the analyses of the data collected in the randomised clinical feasibility trial for early mobilisation by head-up tilt with stepping versus standard care after severe traumatic brain injury. The primary feasibility outcomes are the proportion of included participants who were randomised compared with all screened patients; the proportion of participants allocated to the experimental intervention who received at least 60% of the planned exercise sessions; and safety outcomes such as severe adverse events and reactions and adverse events and reactions. Exploratory clinical outcomes are suspected unexpected severe adverse reactions, the coma recovery scale – revised, the early functional ability scale, and the functional independence measure. Explorative physiological outcomes are electrocardiography, mean arterial pressure, middle cerebral artery blood flow velocity all obtained during the head-up tilt test. From the first head-up tilt test and five days onwards, a continuous electrocardiographic heart rate was measured. The detailed description includes the statistical analysis including use of multiple imputation and Trial Sequential Analysis.

Conclusions: The present statistical analysis plan serves to minimise potential trial reporting bias and selective P hacking and to improve transparency. This feasibility trial will be used for deciding to launch and designing a larger multicentre randomised clinical trial.

Trial registration: ClinicalTrials.gov identifier: NCT02924649. Registered on 3 October 2016.
Textural and chemical variations of micas as indicators for tungsten mineralization: Evidence from highly evolved granites in the Dahutang tungsten deposit, South China
Authors: Yin Rong , Han Li , Huang Xiao-Long , Li Jie , Li Wu-Xian , Chen Lin-Li
Published: March 2019

The Dahutang tungsten deposit, located in the Yangtze Block, South China, is one of the largest tungsten deposits in the world. Tungsten mineralization is closely related to Mesozoic granitic plutons. A drill core through a pluton in the Dalingshang ore block in the Central segment of the Dahutang tungsten deposit shows that the pluton is characterized by multi-stage intrusive phases including biotite granite, muscovite granite, and Li-mica granite. The granites are strongly peraluminous and rich in P and F. Decreasing bulk-rock (La/Yb)N ratios and total rare earth element (ΣREE) concentrations from the biotite granite to muscovite granite and Li-mica granite suggest an evolution involving the fractional crystallization of plagioclase. Bulk-rock Li, Rb, Cs, P, Sn, Nb, and Ta contents increase with decreasing Zr/Hf and Nb/Ta ratios, denoting that the muscovite granite and Li-mica granite have experienced a higher degree of magmatic fractionation than the biotite granite. In addition, the muscovite and Li-mica granites show M-type lanthanide tetrad effect, which indicates hydrothermal alteration during the post-magmatic stage. The micas are classified as lithian biotite and muscovite in the biotite granite, muscovite in the muscovite granite, and Li-muscovite and lepidolite in the Li-mica granite. The Li, F, Rb, and Cs contents of micas increase, while FeOT, MgO, and TiO2 contents decrease with increasing degree of magmatic fractionation. Micas in the muscovite granite and Li-mica granite exhibit compositional zonation in which Si, Rb, F, Fe, and Li increase, and Al decreases gradually from core to mantle, consistent with magmatic differentiation. However, the outermost rim contains much lower contents of Si, Rb, F, Fe, and Li, and higher Al than the mantle domains due to metasomatism in the presence of fluids. The variability in W contents of the micas matches the variability in Li, F, Rb, and Cs contents, indicating that both the magmatic and hydrothermal evolutions were closely associated with W mineralization in the Dahutang deposit. The chemical zoning of muscovite and Li-micas not only traces the processes of W enrichment by magmatic differentiation and volatiles but also traces the leaching of W by the fluids. Therefore, micas are indicators not only for the magmatic–hydrothermal evolution of granite, but also for tungsten mineralization.
Impact of land use on water resources via a Gaussian process emulator with dimension reduction
Authors: Owen Nathan E. , Liuzzo Lorena
Published: March 2019

The replacement of models by emulators is becoming a frequent approach in environmental science due to the reduction of computational time, and different approaches exist in the water resources modelling literature. In this work, an emulator to mimic a hydrological model at catchment scale is proposed, taking into account the effect of land use on the hydrological processes involved in water balance. The proposed approach is novel for its combination of techniques. The dimension of the temporal model output is reduced via principal component analysis, and this reduced output is approximated using Gaussian process emulators built on a conditioned Latin hypercube design to reflect constrained land use inputs. Uncertainty from both the model approximation and the dimension reduction is propagated back to the space of the original output. The emulator has been applied to simulate river flow in a rural river basin located in south west England, the Frome at East Stoke Total, but the methodology is general. Results showed that the use of the emulator for water resources assessment at catchment scale is an effective approach, providing accurate estimates of the model output as a function of land use inputs, for a reduction of the computational burden.
The impact of household connection to public network wastewater systems: regulatory impact assessment
Authors: de Carvalho Bruno Eustaquio , Costa Samuel Alves Barbi , Marques Rui Cunha , Netto Oscar Cordeiro
Published: March 2019

Brazil faces a severe lack of wastewater coverage. Even in urban areas, wastewater is directly disposed of in watercourses without any treatment for a large part of the population. Although the federal, state, and local governments have invested in water and wastewater services (WWS), the expected results have not been achieved. To overcome this problem, the present paper provides an opportunity to observe an ex-ante regulatory impact assessment (RIA) as a policy tool in Brazil. The regulatory policy options will be appraised through the multiple criteria decision analysis (MCDA) according to the following objectives: (i) protect the customers with respect to social aspects; (ii) safeguard the economic, operational and infrastructure sustainability; and (iii) protect the environment. The results show that by making decisions based on evidence, policy makers should reduce the households not connected to wastewater services by 75% and for that they should incur BRL 33 million to the year 2023. Hence, the extra revenues to be obtained with these new connections are capable of making a surplus estimated as BRL 42 million for the same period. This study promotes the use of RIA as a rational, robust and transparent decision framework by the regulatory agencies worldwide.
The effects of a full-scale anaerobic side-stream reactor on sludge decay and biomass activity
Authors: Velho V. F. , Andreottola G. , Foladori P. , Costa R. H. R.
Published: March 2019

A full-scale anaerobic side-stream reactor (ASSR) for sludge reduction was monitored in terms of sludge production and compared with the previous conventional activated sludge configuration (CAS). A detailed solid mass balance was calculated on the whole full-scale plant to estimate the sludge reduction associated with the ASSR. The activity of the biomass, which undergoes alternation of aerobic and anaerobic conditions, was investigated by the respirometric test. The ASSR promoted a reduction of heterotrophic biomass activity and the substrate consumption rate in the activated sludge implemented with ASSR (AS + ASSR) was 36% smaller than in the CAS period. The solid mass balance indicated a sludge reduction of 28%. During the 270-day operation, the observed sludge yield passed from 0.438 kgTSS/kgCOD in the CAS to 0.315 in the AS + ASSR configuration. The solubilization of chemical oxygen demand (COD), NH4+-N and orthophosphate were verified under anaerobic conditions. The results suggest that the possible mechanisms of sludge reduction were the increase of the system sludge retention time (SRT) by ASSR addition, and the reduction in heterotrophic biomass activity added to the organic compounds' hydrolysis.
Assessment of the level of metropolitan cities transport system development
Authors: Karasev Oleg I. , Krivtsova Anna O.
Published: March 2019

Purpose of the study.The study focuses on issues of the level assessment of transport system development of large cities. Despite the wide variety of studies on this issue, there is currently no universal approach to assessing the level of development of the transport system at megalopolises. The present study aims to create a tool for a comprehensive assessment of various aspects of urban transport development that are important for all categories of transport users, and to provide a comparative analysis of the world’s leading megacities in terms of transport development based on the proposed methodology.

Materials and methods.In the study, the authors apply an approach related to the construction of integral indexes and ratings of cities based on the values of these indexes. In the calculations of the index, the authors use statistical data from authoritative open sources and information systems of national and municipal government.

Results.Based on the results of the world practice analysis, the authors propose the Urban Transport Development Index developed in order to compare the level of transport system development in various cities. The Index provides an opportunity to identify the weaknesses and strengths of cities, to find reserves for the further improvement and development of recommendations in the field of transport policy on this basis. The Index consists of four sub-indexes: the availability of transport services for the urban population, the quality of transport services, road traffic security and the ecological impact of transport, and freight logistics performance. The Index reflects the main aspects of urban transport development and shows the views of different categories of population on the level of transport services. The paper examines the level of transport system development for 2010, 2015, 2016 and 2017 of a group of comparable cities, which includes Hong Kong, London, Mexico, Moscow, New York, St. Petersburg, Singapore, Istanbul, Tokyo and Shanghai. The results showed that Tokyo and London have occupied the leading positions during the period under review. For the seven years Moscow, St. Petersburg and Shanghai have showed the best dynamics of the Index.

Conclusion.The proposed method allows both to evaluate the effectiveness of individual regulatory measures known in the practice of other cities, and to simulate their impact on the transport system of the city. The paper concludes with recommendations for further development of cities’ transport systems.
Potential investment to professional sport subjects
Authors: Litvishko Oleg V. , Veynberg Roman R.
Published: March 2019

Purpose of the study.The introduction of financial discipline rules by the Union of European Football Associations started a new stage in the development of the football industry. According to the UEFA statistical report in 2017, football clubs for the first time reported a total profit of more than 600 million Euros, while a few years earlier the total losses of clubs representing the highest European football divisions were 1.7 billion Euros. This fact indicates a possible change in the investment attractiveness of sports clubs. The purpose of this study is to assess the presence of the investment potential of the football industry as a possible object of capital investment.

Materials and methods.The study analyzed the data obtained from the official statistical sources, including a comparative UEFA report for 2017 on the licensing of clubs “Landscape of European Club Football”, normative legal acts regulating public relations in the field of professional sports, publishing in periodicals and the Internet, illustrating the practice and problems of professional sports development, as well as statistical data from the portals www.stoxx. com and www.investing.com. The study applies such methods of scientific cognition as a method of statistical and economic analysis, comparison, analogies, synthesis, as well as the method of measuring and aggregating data, the graphical and tabular method.

Results of the research.When considering the shares of professional sports clubs as objects of capital investment, it is advisable for investors to pay attention to the functional type of assets that such organizations possess and the degree of diversification of their activities. The structure of non-current assets and the share attributable to tangible assets - sports infrastructure and other objects, is an important factor affecting the specific risks inherent in the activities of sports subjects, which allows to compensate losses incurred as a result of not achieving the goal set for the team for the season due to revenues from other activities that affect the investment attractiveness of the club.

Conclusion. Based on the results, we can draw the following conclusions. The football industry has significant revenue growth potential. The increase in the financial profitability of professional sports subjects is accompanied by a rise in the stock index quotes, which accumulates the shares of European public football clubs. The comparative analysis carried out in the research indicates the attractiveness of these financial instruments as an investment object. However, such investments are characterized by a high degree of risk due to the specificity inherent in the professional sports industry. From the total number of factors affecting the exchange rate fluctuations of football clubs' shares, one can single out the most significant indicators such as the outcome and significance of the match, the nature of the tournament, and the sports (physical) form of the team.
Poly(vinyl pyridine)s: A Versatile Polymer in Catalysis
Authors: Khaligh Nader Ghaffari , Abbo Hanna S. , Johan Mohd Rafie , Titinchi Salam J. J.
Published: March 2019

The PVP and its derivatives have been broadly applied in polymers, organic syntheses, and catalysis processes. The crosslinked PVP is a well-known polymer support for numerous reagents and catalysts. Cross-linked PVPs are commercially available polymers and have attracted much attention over the past due to their interesting properties such as the facile functionalization, high accessibility of functional groups, being nonhygroscopic, easy to prepare, easy filtration, and swelling in many organic solvents. A brief explanation of the reported applications of PVPs in different fields followed by the discussion on the implementation of methodologies for catalytic efficiency of PVP-based reagents in the organic synthesis is included. The aim is to summarize the literature under a few catalytic categories and to present each as a short scheme involving reaction conditions. In the text, discussions on the synthesis and the structural determination of some typical polymeric reagents are presented, and the mechanisms of some organic reactions are given. Where appropriate, advantages of reagents in comparison with the previous reports are presented. This review does not include patent literature.
Vancomycin Therapeutic Regime Adjustment in Newborns and Infants with Bacterial Infection: Case Series
Authors: Bidu Nadielle S. , Fernandes Bruno J.D. , Dias Eduardo J.C. , Filho Jucelino N.C. , Bastos Regina E.A. , Godoy Ana L.P.C. , Azeredo Francine J. , Pedreira Joice N.R. , Couto Ricardo D.
Published: March 2019

Background:

Vancomycin is used mostly to overcome infections caused by methicillinresistant
microorganisms. There are no well-established administration protocols for neonates and infants,
so the leak of a specific administration regime in that population may lead to serum concentrations
beyond the specified range.

Objective:

This case series evaluated the pharmacokinetics adjustment from a vancomycin therapeutic
regimen prescribed to neonates and infants with bacterial infection at a neonatal public hospital intensive-
care-unit, with the primary purpose to verify cases of nephrotoxicity.

Methods:

Three neonates and four infants taking vancomycin therapy, hospitalized in a public hospital
from November 2014 to March 2015, were included in the study. Vancomycin serum concentrations
were determined by particle-enhanced-turbidimetric inhibition-immunoassay. The vancomycin concentrations
were used for dose adjustment by USC*Pack-PC-Collection®, a non-parametric maximization
program. The trough serum concentration range of 10 to 20mg.L-1 was considered therapeutic.

Results:

Three patients had serum concentration outside the reference-range, one with subtherapeutic,
and two with supratherapeutic concentrations. All patients had concomitant use of drugs which interfered
with vancomycin distribution and excretion pharmacokinetics parameters, including drugs that
may enhance nephrotoxicity. One patient showed signs of acute renal damage, by low vancomycin and
creatinine estimated clearances.

Conclusion:

The pharmacokinetic adjustment has been proven to be a useful and necessary tool to
increase therapeutic efficacy and treatment benefits. The standard dose of vancomycin can be used to
initiate therapy in neonates and infants admitted to the ICU, but after reaching the drug steady state,
the dosing regimen should be individualized and guided by pharmacokinetic parameters.
Evaluation of Luciferase Thermal Stability by Arginine Saturation in the Flexible Loops
Authors: Kargar Farzane , Mortazavi Mojtaba , Torkzadeh-Mahani Masoud , Lotfi Safa , Shakeri Shahryar
Published: March 2019

Background:

The firefly luciferase enzyme is widely used in protein engineering and diverse
areas of biotechnology, but the main problem with this enzyme is low-temperature stability. Previous
reports indicated that surface areas of thermostable proteins are rich in arginine, which increased
their thermal stability. In this study, this aspect of thermophilic proteins evaluated by mutations of surface
residues to Arg. Here, we report the construction, purification, and studying of these mutated luciferases.

Methods:

For mutagenesis, the QuikChange site-directed mutagenesis was used and the I108R,
T156R, and N177R mutant luciferases were created. In the following, the expression and purification
of wild-type and mutant luciferases were conducted and their kinetic and structural properties were analyzed.
To analyze the role of these Arg in these loops, the 3D models of these mutants’ enzymes were
constructed in the I-TASSER server and the exact situation of these mutants was studied by the
SPDBV and PyMOL software.

Results:

Overall, the optimum temperature of these mutated enzymes was not changed. However, after
30 min incubation of these mutated enzymes at 30°C, the I108R, T156R, N177R, and wild-type kept the
80%, 50%, 20%, and 20% of their original activity, respectively. It should be noted that substitution of
these residues by Arg preserved the specific activity of firefly luciferase.

Conclusion:

Based on these results, it can be concluded that T156R and N177R mutants by compacting
local protein structure, increased the thermostability of luciferase. However, insertion of positively
charged residues in these positions create the new hydrogen bonds that associated with a series of
structural changes and confirmed by intrinsic and extrinsic fluorescence spectroscopy and homology
modeling studies.
Computational Protein-Protein Docking Reveals the Therapeutic Potential of Kunitz-type Venom against hKv1.2 Binding Sites
Authors: Khalid Rida , Noureen Nighat , Kamal Mohammad Amjad , Batool Sidra
Published: March 2019

Background & Objective:

Kunitz-type venoms are bioactive proteins isolated from a wide
variety of venomous animals. These venoms are involved in protease inhibitory activity or potassium
channel blocking activity. Therefore, they are reported as an important source for lead drug candidates
towards protease or channel associated diseases like neurological, metabolic and cardiovascular disorders.

Methods:

This study aimed to check the inhibitory action of Kunitz-type venoms against potassium
channels using computational tools.

Results:

Among potassium channels, Human Voltage-Gated Potassium Channel 1.2 (hKv1.2) was
used as a receptor whereas Kunitz-type peptides from the venoms of various species were selected as
ligand dataset.

Conclusion:

This study helped in finding the binding interface between the receptor and ligand dataset
for their potential therapeutic use in treating potassium channelopathies.
Bioavailability and Pharmaco-therapeutic Potential of Luteolin in Overcoming Alzheimer’s Disease
Authors: Ali Fahad , Siddique Yasir Hasan
Published: March 2019

Luteolin is a naturally occurring, yellow crystalline flavonoid found in numerous dietary
supplements we frequently have in our meals. Studies in the last 2 decades have revealed its therapeutic
potential to reduce the Alzheimer’s disease (AD) symptoms in various in vitro and in vivo models.
The anti-Alzheimer’s potential of luteolin is attributed to its ability to suppress Aβ as well as tau aggregation
or promote their disaggregation, down-regulate the expression of COX-2, NOS, MMP-9,
TNF-α, interleukins and chemokines, reduce oxidative stress by scavenging ROS, modulate the activities
of transcription factors CREB, cJun, Nrf-1, NF-κB, p38, p53, AP-1 and β-catenine and inhibiting
the activities of various protein kinases. In several systems, luteolin has been described as a potent antioxidant
and anti-inflammatory agent. In addition, we have also discussed about the bio-availability of
the luteolin in the plasma. After being metabolized luteolin persists in plasma as glucuronides and
sulphate-conjugates. Human clinical trials indicated no dose limiting toxicity when administered at a
dose of 100 mg/day. Improvements in the formulations and drug delivery systems may further enhance
the bioavailability and potency of luteolin. The current review describes in detail the data supporting
these studies.
Molecular Docking of Azadirachtin in Nuclear Ecdysone Receptor
Authors: de Oliveira Daniel Augusto Barra , da Silva Alcedino Venancio , dos Santos Niculau Edenilson
Published: March 2019

Background:

The azadirachtin is a triterpenoid associated with growth inhibition
in several kinds of insects which cause epidemic diseases like Dengue, Chikungunya
and Malaria. Azadirachtin acts by inhibiting the Ecdysone Receptor (EcR), which is responsible
from larvae phase in insects. However, the interaction between the azadirachtin
molecule and the Ecdysone Receptor is unknown. In this work, we used the program Dock
Thor to generate several azadirachtin conformations inside the EcR binding site. The ten
most stable conformations were optimized with the ONIOM approach present in the
Gaussian 09 program. The interaction energy was calculated between the azadirachtin
molecule and EcR receptor. Theoretical calculation shows that the azadirachtin molecule
interacts with the same amino acids present in the ecdysone EcR interaction. These results
will be useful to design new EcR inhibitors, which can be used in the control of some diseases
based on insect proliferations.

Objective:

To understand the interaction between the natural insecticide azadirachtin and
the Ecdysone Receptor.

Methods:

A combination of Dock Thor program with QM-MM calculation was used in order
to obtain the most favorable molecular structures.

Results:

The hydrogens bond obtained by Dock Thor Program combined with QM-MM
calculation suggest the azadirachtin interact with EcR in the same way that ecdysone molecule.

Conclusion:

The interaction mode that the molecule azadirachtin inhibits EcR in order to
avoid insect proliferation was described.
Влияние фазового перехода второго рода на электропроводность структуры металл/полупроводник
Authors: Набиуллин И.Р. , Гадиев Р.М. , Лачинов А.Н.
Published: March 2019

AbstractThe properties of the Cr– p -Si potential barrier near the temperature of the antiferromagnetic–paramagnetic phase transition in chromium are investigated. A significant change in the potential barrier and an anomalous increase in the conductivity in the Cr– p -Si–Au structure are observed near the temperature of the second-order antiferromagnetic–paramagnetic phase transition in chromium. It is established that current fluctuations in the structure are enhanced when approaching the phase-transition point. The experimental results are interpreted based on the assumption that the observed change in the electron-transport properties of the Cr–Si interface is due to a shift of the Fermi quasi-level in chromium as a result of the second-order phase transition.
Simulated contrast of two dislocations -=SUP=-*-=/SUP=-
Authors: Ledra M. , El Hdiy A.
Published: March 2019

AbstractA three-dimensional Monte Carlo simulation algorithm is used to study the contrast of two dislocations perpendicular to the irradiated surface of an n -doped silicon sample in the electron beam induced current mode. The dislocations are positioned in the irradiation trajectory, and each of both is considered as a cylinder where the minority carrier diffusion length varies abruptly from a low inside dislocations up to a high value outside dislocations. The EBIC contrast was obtained by simulating the random diffusion of carriers generated at point-like sources randomly distributed within the generation volume. Results are analyzed on the basis of change in the generation volume in the bulk of the sample and of carrier trapping process inside dislocations. The EBIC contrast increases with the increase of the electron beam energy. It also increases when the minority diffusion length inside dislocations, or their separating distance decreases.
Локализация носителей в квантовых точках с одноосной анизотропией формы и состава
Authors: Семина М.А. , Головатенко А.А. , Шубина Т.В. , Родина А.В.
Published: March 2019

AbstractThe electronic and hole states in quantum dots (QD) of cubic II–VI semiconductors with a spheroidal shape and uniaxial anisotropy have been studied theoretically. The smooth potential energy profiles simulated by the Gauss function in all three spatial directions are considered. The energy level lowering and the energy splitting of the hole state from the valence band top Γ_8 by momentum 3/2 into the states with projections ±3/2, ±1/2 on the anisotropy axis are analyzed. The QD anisotropies of three types are considered: the QD size anisotropy, the QD potential barrier anisotropy, and the combined anisotropy. In the first case, flattened quantum dots, in which the characteristic size in the structure plane is larger than the size along the anisotropy axis, are considered. In the second case, QDs, in which the potential barrier height in the plane is lower than that along the anisotropy axis, are considered. In the third case, flattened quantum dots with the anisotropy of the size and the potential barrier are considered. The conditions of the charge carrier localization inside QD have been found, and the influence of the form and composition anisotropies on the energies of exciton transitions in the structures with Cd_ x Zn_1 – _ x Se quantum dots are discussed.
Фазовый переход в цилиндрических изинговых нанопроволоках и нанотрубках: приближение теории молекулярного поля
Authors: Танрывердиев В.А. , Тагиев В.С. , Абдуллаев М.Н. , Керимова Г.Г.
Published: March 2019

AbstractWithin the approximation of the molecular field theory, the critical behavior of cylindrical Ising nanowires and nanotubes is studied. The model considered in this work consists of ferromagnetic spins S _c situated in the core of the system and ferromagnetic spins S _s situated on the surface wall; they are interconnected by the exchange coupling J _1. The transition temperature T _c for such systems has been calculated as a function of exchange interaction parameters. The influence of the surface exchange interaction and surface coupling on the magnetodynamic behavior of the system have been studied. Some characteristic properties obtained on the phase diagram are related to the ratio of characteristic physical parameters on the surface and core of the abovementioned nanostructures.
Временные зависимости диэлектрических и акустических свойств в монокристаллах PbFe-=SUB=-0.5-=/SUB=-Nb-=SUB=-0.5-=/SUB=-O-=SUB=-3-=/SUB=- и PbFe-=SUB=-0.5-=/SUB=-Nb-=SUB=-0.5-=/SUB=-O-=SUB=-3-=/SUB=---7PbTiO-=SUB=-3-=/SUB=-
Authors: Камзина Л.С. , Кулакова Л.А. , Luo H.
Published: March 2019

AbstractThe time changes of permittivity, damping and velocity of sound are studied for PbFe_0.5Nb_0.5O_3 and PbFe_0.5Nb_0.5O_3–7PbTiO_3 single crystals in the electric fields of 0 < E < 6 kV/cm. The room-temperature local symmetry of these compounds is shown to be rather more monoclinic than rhombohedral, which is typical of other similar systems. No abrupt sound attenuation anomalies are observed upon the phase transition into the ferroelectric phase in the electric field. The effects seem to be far from the crystal symmetry changes and are attributed to the gradual transition of near-range monoclinic domains into long-range monoclinic domains, as well as to the emergence of the ferroelectric phase. The polarized phase induced in the electric field is only partially stable.
Влияние механического воздействия на рельеф поверхности металлического стекла Fe-=SUB=-77-=/SUB=-Ni-=SUB=-1-=/SUB=-Si-=SUB=-9-=/SUB=-B-=SUB=-13-=/SUB=-
Authors: Корсуков В.Е. , Анкудинов А.В. , Бетехтин В.И. , Бутенко П.Н. , Вербицкий В.Н. , Гиляров В.Л. , Корсукова М.М. , Нарыкова М.В. , Обидов Б.А.
Published: March 2019

AbstractThe micro- and nanoreliefs of the loaded surfaces of a Fe_77Ni_1Si_9B_13 metal glass are probed via scanning tunneling and atomic force microscopies, scanning electron microscopy, and X-ray fluorescence. The fractal characteristics of surfaces are evaluated via the multifractal approach. As found, the variations in a singularity spectrum width, calculated from the tunneling and atomic force microscopies, may be useful for predicting the forthcoming fracture. An increase in the breaking strength of ribbons subjected to hydrostatic compression is due to decreasing microporosity of a near-surface layer, which corresponds to the surface smoothing.
Монодисперсные сферические наночастицы Gd-=SUB=-x-=/SUB=-Si-=SUB=-y-=/SUB=-O-=SUB=-z-=/SUB=- : Eu-=SUP=-3+-=/SUP=- для магнитно-резонансной томографии и оптической визуализации
Authors: Еуров Д.А. , Курдюков Д.А. , Shornikova E.V. , Qiang G. , Яковлев Д.Р. , Bayer M. , Голубев В.Г.
Published: March 2019

AbstractThe melt method is used for synthesizing monodispersed spherical silica nanoparticles Gd_ x -Si_ y O_ z :Eu^3+. The particle diameter is 450 nm, and the standard deviation does not exceed 5%. The nanoparticles have a line luminescence spectrum with a dominant band at 614 nm. The effect of a constant magnetic field up to 15 T on the intensity and shape of the luminescence spectra of Eu^3+ ions is studied. It is shown that the obtained material has a stable photoluminescence, the intensity of which does not depend on the magnetic field in the entire studied range. The synthesized nanoparticles Gd_ x Si_ y O_ z : Eu^3+ are promising for use as a contrast agent for magnetic resonance tomography and luminescent marker.
Дифференциальные характеристики поля течения перерасширенной газовой струи в окрестности кромки сопла
Authors: Чернышов М.В. , Гвоздева Л.Г.
Published: March 2019

AbstractA parametric study of the features of the flow field of a plane and axisymmetric overexpanded ideal gas jet in the vicinity of the nozzle edge has been conducted over the entire theoretically admissible range of determining parameters (nozzle divergence angles, exhaust Mach numbers, jet incalculabilities, and gas adiabat indicators). The exhaust parameters that correspond to the extremes of the differential characteristics of a shockwave falling (descending) from the edge and the flow field behind it have been revealed. A significant difference in the character of changes in the characteristics of the shockwave and the flow field behind it depending on the type of symmetry of the gas jet has been found and studied.
Распространения импульсного давления при электрогидравлическом бурении
Authors: Ахмадиев Б.А. , Татыбеков А. , Шуюшбаева Н.Н. , Танашева Н.К.
Published: March 2019

AbstractWe have analyzed the propagation of pulsed pressure produced by electric discharges in a heterogeneous liquid during well drilling. The pressure dynamics has been calculated based on theoretical analysis of the nonlinear process of the electrohydraulic effect in a heterogeneous medium. As a result of analysis, the time dependences of the relative pressure and shock front coordinate have been obtained.
Исследование влияния размеров образцов на скорость деформации при определении прочностных динамических характеристик материала
Authors: Евстифеев А.Д. , Волков Г.А. , Чеврычкина А.А. , Петров Ю.В.
Published: March 2019

AbstractTest results are presented for an additive material prepared of acrylonitrile-butadiene-styrene on a 3D printer. Dynamic tension experiments have been carried out using a tower-type drop hammer with an accelerator. Data obtained from different specimens demonstrate that high-strain-rate tensile experiments are feasible if the working part of the specimen is decreased. A theoretical analysis of test data using the incubation time criterion has been performed, and it has been found that analytical results are in good agreement with experimental data.
Синтез гексагональных слоев AlN и GaN на Si(100)-подложке методом хлоридной газофазной эпитаксии
Authors: Бессолов В.Н. , Гущина Е.В. , Коненкова Е.В. , Коненков С.Д. , Львова Т.В. , Пантелеев В.Н. , Щеглов М.П.
Published: March 2019

AbstractSynthesis of AlN and GaN layers on a Si(100) substrate by chloride vapor-phase epitaxy has been considered. The process includes sulfidizing of the silicon surface, nucleation and growth of an AlN layer, and then formation of a GaN/AlN structure. It has been found that in the case of a (100)Si substrate, GaN nucleates on buffer AlN layers that may have two crystallographic orientations in contrast to a Si(111) substrate, on which a buffer layer may have only one orientation. It has been shown that the treatment of the Si(100) substrate in an aqueous solution of (NH_4)_2S decreases the FWHM of the rocking curve for GaN(0002) by a factor of 1.5.
Инверсия типа проводимости тонких пленок n-InSe под действием лазерного излучения
Authors: Кязым-заде А.Г. , Салманов В.М. , Гусейнов А.Г. , Мамедов Р.М. , Агамалиев З.А. , Салманова А.А. , Ахмедова Ф.М.
Published: March 2019

AbstractConductivity inversion in thin n -InSe films under intense pulsed laser irradiation was obser. A p – n structure based on indium selenide formed between irradiated and nonirradiated regions of a thin-film sample. It was confirmed by EDAX analysis that the composition of the sample remained the same after irradiation. The conductivity inversion is attributed to a change in the dynamics of lattice defects under heating.
Модель термического окисления кремния
Authors: Фадеев А.В. , Девятко Ю.Н.
Published: March 2019

AbstractNanometer-thick silicon oxide films are needed for miniaturization and increase in the working rate of electronic devices. Interpretation of the initial stages of silicon oxidation is necessary for fabrication of such structures. A theoretical model of the thermal oxidation of thin silicon monolayers that takes into account an increase in the stress in the transition (oxide–substrate) layer due to oxygen accumulation therein is proposed.
Интерференция между E1- и M1-амплитудами перехода из состояния H в C молекулы ThO
Authors: Петров А.Н. , Скрипников Л.В.
Published: March 2019

AbstractThe systematic error in experiments concerning searching for the electric dipole moment of an electron due to the Stark interference between the E 1 and M 1 amplitudes of the transition from the $${{H}^{3}}{{\Delta }_{1}}$$ state to $${{C}^{1}}\Pi $$ of a ThO molecule has been calculated. The calculations show that the error is about three orders of magnitude lower than the current limitation on the electric dipole moment of electron.
Влияние ионов In-=SUP=-3+-=/SUP=- и Ga-=SUP=-3+-=/SUP=- на запрещенную зону кристаллов щелочно-земельных фторидов: неэмпирический расчет
Authors: Мясникова А.С. , Богданов А.И.
Published: March 2019

AbstractThe results of nonempirical quantum chemical calculations of CaF_2, SrF_2, and BaF_2 crystals that were activated by In^3+ and Ga^3+ ions have been presented. The calculations were performed in the framework of density functional theory using the VASP software complex. The estimation of the width of the band gap of defect-free crystals have been carried out by different methods and the influence of impurity ions on the band gap width has been estimated as well as the possibility of getting rid of shallow traps by introducing an impurity of indium or gallium has been investigated.
Особенности спектров оптического поглощения интерметаллических соединений GdFe-=SUB=-2-=/SUB=- и LuFe-=SUB=-2-=/SUB=-
Authors: Князев Ю.В. , Кузьмин Ю.И.
Published: March 2019

AbstractThe optical properties of binary GdFe_2 and LuFe_2 compounds are studied by the ellipsometric method in the 0.22–17 μm spectral range. A number of spectral and electronic characteristics are determined. The experimental dependences of optical conductivity in the light quantum absorption region are interpreted based on previously published calculations of electronic states densities.
Возбуждение лазеров на парах меди прямым разрядом накопительного конденсатора через быстродействующие фототиристоры
Authors: Кюрегян А.С.
Published: March 2019

AbstractThe possibility of using a “pulsed fiber laser–photothyristor” optocoupler as a switch in the excitation schemes of copper vapor lasers (CVLs) has been investigated. It has been shown that such a switch has a nanosecond performance and is able to form monopolar and alternating current pulses through CVLs with a power of up to 10 MW and a repetition rate of tens of kilohertz when an electrical efficiency of the excitation circuit is more than 95%. A simple but very accurate model of a photothyristor is proposed, which can be used in full-scale CVL modeling programs.
Световые пули в периодически неоднородной среде ориентированных углеродных нанотрубок в оптическом резонаторе
Authors: Белоненко М.Б. , Двужилов И.С. , Двужилова Ю.В. , Борознин С.В.
Published: March 2019

AbstractThe problem of the propagation dynamics of three-dimensional ultimately short optical pulses in an optical cavity in a periodically inhomogeneous medium of oriented carbon nanotubes is considered. It is shown numerically that such pulses demonstrate stable and sustainable propagation. In addition, it is shown that one can control for the pulse propagation rate and modify the pulse shape by varying parameters of the inhomogeneous medium.
Оптические решеточно-волноводные сенсоры на основе халькогенидных стекол
Authors: Наливайко В.И. , Пономарева М.А.
Published: March 2019

AbstractThe operating principle of the optical grating waveguide sensors is considered. The waveguide sensitivity and detection limit of sensors with waveguides of oxide and chalcogenide glasses are compared. The advantages of the grating waveguide sensors with waveguides with a high contrast of refraction indices are shown. The conditions of obtaining a maximum waveguide sensitivity of the grating waveguide sensors are formulated.
Филаментация и самофокусировка электронных пучков в вакуумных и газовых диодах
Authors: Олешко В.И. , Тарасенко В.Ф. , Бураченко А.Г. , Nguyen V.V.
Published: March 2019

AbstractIn this paper, we experimentally studied pulsed electron beams with a high local density. The conditions in which the energy density cumulation is observed during the interaction of electrons with the anode are shown to develop in vacuum and gas diodes at nanosecond and subnanosecond durations of a beam current pulse and a decrease in the interelectrode gap. The average electron energy in filamentation and self-focusing of an electron beam in a vacuum diode of an accelerator at a current of ~2 kA and a no-load voltage of ~400 kV was established to be 50–100 keV while the energy density was 10^9–10^10 J/cm^3. It is confirmed that the beam current density in a gas diode can exceed 1 kA/cm^2. It is hypothesized that superdense electron beams in vacuum and gas diodes are formed as a result of avalanche multiplication of runaway electrons in the cathode–anode gap plasma.
Преобразование полупроводниковых наночастиц в плазмонные материалы путем направленной замены органических лигандов, связанных с их поверхностью
Authors: Самохвалов П.С. , Володин Д.О. , Бозрова С.В. , Довженко Д.С. , Звайгзне М.А. , Линьков П.А. , Нифонтова Г.О. , Петрова И.О. , Суханова А.В. , Набиев И.Р.
Published: March 2019

AbstractPlasmonic nanoparticles have become a popularly accepted research tool in optoelectronics, photonics, and biomedical applications. The relatively recently appearing semiconductor plasmonic nanoparticles, as opposed to metal ones, are characterized by infrared plasmonic optical transitions and their application has a great future. In this work, the possibility of conversion of semiconductor (excitonic) fluorescence nanocrystals, i.e., quantum dots of the CuInS_2 composition, to plasmonic nanoparticles by postsynthetic treatment without changes in the chemical composition of inorganic part of the nanocrystals was demonstrated for the first time ever.
Сверхпроводящий контакт для ВТСП-лент второго поколения
Authors: Куликов И.В. , Черных М.Я. , Крылова Т.С. , Овчаров А.В. , Черных И.А. , Занавескин М.Л.
Published: March 2019

AbstractAn approach of the epitaxial jointing of the GdBa_2Cu_3O_7 – δ-based tapes using the YBa_2Cu_3O_7 – δ layer is proposed. The structural and electrical characteristics of the formed joint have been investigated. Using the scanning transmission electron microscopy, the cross section of the joined region has been studied, partial melting of the YBa_2Cu_3O_7 – δ layer has been observed, and the solid-phase diffusion with the formation of the (Gd, Y)Ba_2Cu_3O_7 – δ, Y_2BaCuO_5, BaCuO_2, and CuO phases has been established. It is shown that the current-carrying capability of the superconducting joint is over 30% of the initial tape current.
Переходные процессы при токовой перегрузке в цепи переменного тока с ВТСП-проводом
Authors: Мальгинов В.А. , Мальгинов А.В. , Флейшман Л.С.
Published: March 2019

It has been found that the loss of superconductivity in HTSC wires under ac current overload is accompanied by the change in sign of the phase difference between current and voltage. In a stabilized second-generation HTSC wire under an overload the oscillations of ac current and voltage amplitudes have been found due to the oscillations of the normal zone size in the superconducting layer. The change in sign of the phase difference can be applied for a timely registration of a normal zone nucleation in current-carrying conductors of superconducting equipment.