Charge inhomogeneities due to smooth ripples in graphene sheets

We study the effect of the curved ripples observed in the free standing graphene samples on the electronic structure of the system. We model the ripples as smooth curved bumps and compute the Green's function of the Dirac fermions in the curved surface. Curved regions modify the Fermi velocity that becomes a function of the point on the graphene surface and induce energy dependent oscillations in the local density of states around the position of the bump. The corrections are estimated to be of a few percent of the flat density at the typical energies explored in local probes such as scanning tunnel microscopy that should be able to observe the predicted correlation of the morphology with the electronics. We discuss the connection of the present work with the recent observation of charge anisotropy in graphene and propose that it can be used as an experimental test of the curvature effects.Comment: 9 pages, 5 figures. v2: Abstract and discussion about experimental consequences expande

The influenza epidemic in Russia during the 2014–2015 season

The goal of this study was to compare the data on the intensity of the influenza A(H3N2) and B epidemic (especially the death toll) in the 2014–2015 season with the previous epidemic of the 2013-2014 season. The data on weekly morbidity, hospitalization, deaths from influenza, and acute respiratory diseases in different age groups of inhabitants of 59 cities located in 7 Federal districts of the Russian Federation were collected using the database of the Research Institute of Influenza.Analysis of this data showed that the influenza epidemic in 2014-2015 began earlier (in December) compared to the epidemic of 2013-2014, and spread mainly from Europe through Russia to the East. The intensity of the epidemic of 2014-2015 was higher compared to the previous one. The epidemic was more prevalent by regions and cities and a wider engagement of different age groups (except children up to 2 years of age) was observed. At the peak of the epidemic, the morbidity level was higher, the average duration of the epidemic was longer, and the number of patients among cities’ inhabitants (especially among children 7-14 years of age and adults) was higher than in the previous season. The rates of hospitalization with influenza and acute respiratory viral infections (ARVI) among patients older than 65 years were also higher (1.4 times) as well as the frequency of hospitalization with a diagnosis of “influenza” (2.7 times) and the number of deaths from laboratory confirmed influenza (1.8 times).Although the influenza pandemic virus strain A(H1N1)pdm09 was not the main causative agent of the 2015 epidemic and was distributed sporadically it still remained the leading cause of deaths from influenza in the course of this epidemic (45.5% of all cases). The deaths associated with this strain were recorded only in the European part of Russian Federation.The goal of this study was to compare the data on the intensity of the influenza A(H3N2) and B epidemic (especially the death toll) in the 2014–2015 season with the previous epidemic of the 2013-2014 season. The data on weekly morbidity, hospitalization, deaths from influenza, and acute respiratory diseases in different age groups of inhabitants of 59 cities located in 7 Federal districts of the Russian Federation were collected using the database of the Research Institute of Influenza. Analysis of this data showed that the influenza epidemic in 2014-2015 began earlier (in December) compared to the epidemic of 2013-2014, and spread mainly from Europe through Russia to the East. The intensity of the epidemic of 2014-2015 was higher compared to the previous one. The epidemic was more prevalent by regions and cities and a wider engagement of different age groups (except children up to 2 years of age) was observed. At the peak of the epidemic, the morbidity level was higher, the average duration of the epidemic was longer, and the number of patients among cities’ inhabitants (especially among children 7-14 years of age and adults) was higher than in the previous season. The rates of hospitalization with influenza and acute respiratory viral infections (ARVI) among patients older than 65 years were also higher (1.4 times) as well as the frequency of hospitalization with a diagnosis of “influenza” (2.7 times) and the number of deaths from laboratory confirmed influenza (1.8 times). Although the influenza pandemic virus strain A(H1N1)pdm09 was not the main causative agent of the 2015 epidemic and was distributed sporadically it still remained the leading cause of deaths from influenza in the course of this epidemic (45.5% of all cases). The deaths associated with this strain were recorded only in the European part of Russian Federation

Physical properties of thermoelectric zinc antimonide using first-principles calculations

We report first principles calculations of the structural, electronic, elastic and vibrational properties of the semiconducting orthorhombic ZnSb compound. We study also the intrinsic point defects in order to eventually improve the thermoelectric properties of this already very promising thermoelectric material. Concerning the electronic properties, in addition to the band structure, we show that the Zn (Sb) crystallographically equivalent atoms are not exactly equivalent from the electronic point of view. Lattice dynamics, elastic and thermodynamic properties are found to be in good agreement with experiments and they confirm the non equivalency of the zinc and antimony atoms from the vibrational point of view. The calculated elastic properties show a relatively weak anisotropy and the hardest direction is the y direction. We observe the presence of low energy modes involving both Zn and Sb atoms at about 5-6 meV, similarly to what has been found in Zn4Sb3 and we suggest that the interactions of these modes with acoustic phonons could explain the relatively low thermal conductivity of ZnSb. Zinc vacancies are the most stable defects and this explains the intrinsic p-type conductivity of ZnSb.Comment: 33 pages, 8 figure

Innovative Methods in Management and Raising the Quality of Higher Professional Education in Russia

Economic and political changes in contemporary society lead to reforms of many social spheres. The system of education in general and higher professional education in particular is no exception. The issue of ensuring the quality of education has recently attracted great attention in all countries of the world. The key problem of reforming education is raising its quality. In this paper, the object of research was the quality of education provided by higher education institutions. The authors have conducted the analysis of models for raising the quality of education and qualimetry of the laboratory work quality based on a survey of teachers and students. The QFD method was described by the example of its application in five universities of the Russian Federation. It has been proved that this method can provide the university with a planning tool with which higher education institutions can provide services that fully meet the requirements of customers (students, parents, employers, the state and society as a whole), thereby ensuring the suitability of the system to meet external requirements – the Fitness-for-Purpose approach (building goals based on the external environment). In addition, it has also been substantiated that the application of this method in the system of higher professional education will ensure the suitability of the system to achieve its own goals - the Fitness-for-Purpose approach (development, improvement, effective management). Thus, the QFD method will make it possible to support of all types of coordinated activities for the leadership and management of higher education institutions in relation to quality, as well as a set of developed regulatory and methodological documents that determine the content, technologies, methods and means of work of all officials, teachers and students to further improve the quality of educational process, thereby ensuring the competitiveness of higher education institutions and effective development on the global market of educational service

Changes in indicators of the prooxidant-antioxidant system in patients with drug addiction during the rehabilitation

Background: Despite the positive dynamics in this scientific area, the prevalence of drug pathology in Russia and other countries of the world remains unfavorable. Determination of laboratory markers of pathobiochemical processes which are characteristic to the patients with substance use disorder is promising from the standpoint of monitoring the course of the disease and evaluating the effectiveness of therapy.Objective: To determine the characteristic changes in oxidative homeostasis of patients with addiction to psychostimulants and opioids at the rehabilitation and anti‑relapse stage.Material and methods: The study was performed with the participation of 20 relatively healthy male volunteers and 18 male patients with addiction to opioids or psychostimulants who then became participants of the rehabilitation and anti‑relapse course of treatment. Changes in oxidative stress markers during rehabilitation and anti‑relapse treatment were studied.Results: In comparison to the control values at the initial stage of the study, patients of the main group demonstrated decreased values of the iron‑reducing ability of blood plasma – by 25%, as well as those of the sorption radical ability of blood plasma – by 30%; the content of thiol groups of blood plasma proteins decreased by 24% while the concentration of glutathione in erythrocyte suspension lowered by 26%. The level of TBA‑reactive products in erythrocyte suspension corresponded to the control level. The performed rehabilitation manipulations contributed to the partial normalization of oxidative homeostasis, which was confirmed by a statistically significant increase in the ability of radical sorption of blood plasma by 20% and the concentration of reduced glutathione in erythrocyte suspension by 28% in comparison to the initial values of the corresponding parameters in patients of the 2nd group. The TBA‑reactive products remained within the control values.Conclusion: The studied markers are suitable for monitoring the state of oxidative homeostasis in patients with opioid or psychostimulant addiction, the imbalance of which at the end of the rehabilitation and anti‑relapse stage also indicates the prospects for strengthening the antioxidant component as part of drug or nutritional correction

Oxidative stress markers in patients suffering from opioid and psychostimulant dependence syndrome

Background. The available data from clinical studies suggest the essential role of free radical processes in the pathogenesis of drug dependence syndrome. At the same time, there is a limited understanding of using markers of oxidative stress in laboratory monitoring and prediction of drug pathology.Objective. To characterize changes in promising indicators of oxidative stress in patients with psychostimulant and opioid dependence syndrome.Material and Methods. The total study population was divided into three groups of men aged 23–35: healthy controls (n = 20), patients with the opioid (n = 20) and psychostimulant (n = 20) dependence syndrome. Patients were analyzed for the oxidative stress markers while being in therapy for addiction syndrome aimed at treating mental disorders and detoxification.Results. The study of antioxidant activity and blood plasma thiol groups did not reveal any significant differences between patients suffering from opioid and psychostimulant addiction. The values of the parameters mentioned above were maintained by 20–30% lower than the control indices throughout the entire study. The nature of changes in erythrocyte suspension parameters was not so unambiguous. Thus, patients with opioid dependence syndrome were characterized by a 91% increase in thiobarbituric acid (TBA)-reactive materials in the setting of a slightly altered state of the glutathione system parameters. Psychostimulant dependent patients revealed relatively low level of the products of biomolecule oxidative modifications in the erythrocytes that is 52% higher compared to the control values. It decreased during the therapy, but glutathione concentration reduction by 33% and an imbalance of glutathione metabolism were determined.Conclusion. The course of the opioid dependence syndrome is characterized by a pronounced intensification of free radical processes while the common trait for psychostimulant abusers is significant changes in the antioxidant defense system. Therefore, in the first case, it is most justified to conduct a laboratory assessment of indicators of oxidative damage, and in the second one, it is also advisable to determine the markers of the state of individual links of the antioxidant system

ОПРЕДЕЛЕНИЕ УРАНА В ВОДНЫХ РАСТВОРАХ МЕТОДОМ ВРЕМЯПРОЛЕТНОЙ МАСС-СПЕКТРОМЕТРИИ С ИМПУЛЬСНЫМ ТЛЕЮЩИМ РАЗРЯДОМ ПОСЛЕ ЕГО КОНЦЕНТРИРОВАНИЯ ОКИСЛЕННЫМИ УГЛЕРОДНЫМИ НАНОТРУБКАМИ

The pollution of the environment with uranium dictates the need to control the concentration of this element in natural waters to the permissible limits for the stability of the ecosystems and public health. In 2011, WHO set maximum permissible concentration of uranium in water to 0.03 ppm due to the strong toxicity and radioactivity of uranium in water. Therefore, the continuous monitoring of uranium content is an important task for the safety and health of the citizens. To determine the low uranium content in natural waters, the conservation of the studied solutions is necessary. However, this method of storage and transportation is not always simple. In the current paper, as a convenient method of concentrating uranium, preserving the sample and transporting it, we used the method of sorbing uranium on sorbents. Single-layer carbon nanotubes were used as sorbents. Their surfaces were modified using wet chemical oxidation and synthesis with Aerosil A-380 silica. Two schemes were considered for concentrating the uranium on the surface of the sorbent: individual carbon nanotubes and nanotubes modified with silica. The direct analysis was used to determine the content of uranium in the sorbent, namely, time-of-flight mass spectrometry with the pulsed glow discharge (GDMS). The most effective approach for the determination of uranium in water was the sorption of uranium on the tablet consisting of oxidized nanotubes modified with silica. The limit of detection in this case was 0.2 ppb.Keywords: mass-spectrometry, pulsed glow discharge, environment, direct analysis, uranium, carbon nanotubes  DOI: http://dx.doi.org/10.15826/analitika.2020.24.2.001Titova A.D1, Postnov V.N.1, Savinov S.S.1, Stolyarova N.V.2, Ivanenko N.B.2, Chuchina V.A.1, Gubal A.R.1, Ganeev A.A.1,21Saint-Petersburg State University (SPBU),Universitetskaya emb., 7/9, Saint-Petersburg, 199034, Russian Federation2Institute of Toxicology of Federal Medico-Biological Agency,ul. Bekhtereva, 1, Saint-Petersburg, 192019, Russian FederationЗагрязнение окружающей среды ураном диктует необходимость контроля концентрации этого элемента в природных водах до допустимых пределов, что необходимо для стабильности экосистем и здоровья населения. Из-за сильной токсичности и радиоактивности в 2011 году ВОЗ установила предельно допустимую концентрацию урана в воде – 0.03 ppm. При транспортировке проб природной воды с низким содержанием урана (на уровне ПДК) их консервируют. В качестве удобного способа транспортировки пробы и одновременного концентрирования урана в данной работе предложено сорбировать его на однослойных углеродных нанотрубках. Поверхность углеродных нанотрубок предварительно модифицировали химическим окислением и обрабатывали кремнеземом аэросил А-380. Рассматривали два варианта концентрирования урана на поверхность сорбента: индивидуальные и модифицированные кремнеземом углеродные нанотрубки. Для анализа использовали прямой метод определения содержания урана в сорбенте − времяпролетную масс-спектрометрию с импульсным тлеющим разрядом (GD-MS). Показано, что наиболее эффективным подходом для определения урана в воде стала сорбция урана на таблетку, состоящую из модифицированных кремнеземом окисленных нанотрубок. Предел обнаружения при этом составил 0.2 ppb.Ключевые слова: масс-спектрометрия, импульсный тлеющий разряд, окружающая среда, прямой анализ, уран, углеродные нанотрубкиDOI: http://dx.doi.org/10.15826/analitika.2020.24.2.00

Analysis of Protein Markers in Plasma of Patients with Drug Dependence Syndrome: Observational Clinical Study

Background. In drug addiction treatment, the diagnostic process is based on the chemical toxicological determination of the intoxication substrate or its metabolite. Laboratory monitoring and prediction issues that could form the basis of secondary prevention remain unresolved. Specific nervous tissue proteins are considered to be the most promising laboratory markers of drug pathology.Objective — to determine some potential biomarkers of protein-chemical nature in the plasma of patients with drug dependence syndrome.Methods. The study was conducted according to the design of an observational clinical trial at the Narcological Dispensary of Krasnodar Krai in the period from 07.2021 to 07.2022. The main group (group 2) included 31 patients diagnosed with substance dependence syndrome. The control group (group 1, n = 15) consisted of healthy subjects submitted to occupational medical examinations. During the detoxification-stabilization therapy and rehabilitation, 5 proteins were determined in the plasma: brainand glial-derived neurotrophic factors, neuron-specific enolase, alpha-synuclein and calcium-binding protein S100B. Statistical analysis of the data involved the Mann-Whitney test for comparing the values of the control and experimental groups and the Wilcoxon test for comparing the values of one group obtained at different stages of observation. The calculations were carried out using StatPlus version 7 (AnalystSoft Inc., USA).Results. A total of 31 patients were included in the main group, 18 of them were followed up with a diagnosis of opioid dependence syndrome (n = 11) or psychostimulant dependence syndrome (n = 7). Patients dropped out of the study due to their refusal to participate in the study or undergo rehabilitation, or due to relapse of the disease. When admitted to the hospital, patients indicated a 45% decrease in brain-derived neurotrophic factor in the plasma ( p < 0.001), and a 3.9-fold decrease after rehabilitation course ( p < 0.001). Glial-derived neurotrophic factor in the plasma exceeded the controls 1.9 times ( p < 0.001) upon admission to hospital, but rapidly returned to normal values thereafter. Level of neuron-specific enolase in the plasma was also poor, 36% lower than the controls ( p <0.001), but approached the control values by the end of rehabilitation.Conclusion. The study obtained data indicating the changes in neurotrophic factors in the blood plasma of patients with opioid or psychostimulant dependence. The rehabilitation period was marked by a relatively rapid improving level of neurotrophins; however, brain-derived neurotrophic factor remained reduced despite the successful treatment, which may indicate the irreversible changes