3,322 research outputs found
Shock-wave heating mechanism of the distant solar wind: explanation of Voyager-2 data
One of the important discoveries made by Voyager-2 is the nonadiabatic radial
profile of the solar wind proton temperature. This phenomenon has been studied
for several decades. The dissipation of turbulence energy has been proposed as
the main physical process responsible for the temperature profile. The
turbulence is both convected with the solar wind and originated in the solar
wind by the compressions and shears in the flows and by pick-up ions. The
compression source of the solar wind heating in the outer heliosphere appears
due to shock waves, which originated either in the solar corona or in the solar
wind itself. The goal of this work is to demonstrate that the shock-wave
heating itself is enough to explain the temperature profile obtained by
Voyager-2. The effect of shock-wave heating is demonstrated in the frame of a
very simple spherically symmetric high-resolution (in both space and time)
gas-dynamical data-driven solar wind model. This data-driven model employs the
solar-wind parameters at 1 AU with minute resolution. The data are taken from
the NASA OMNIWeb database. It is important to underline that (1) the model
captures the shocks traveling and/or originating in the solar wind, and (2)
other sources of heating are not taken into account in the model. We extended
this simple model to the magnetohydrodynamic (MHD) and two-component models and
found very similar results. The results of the numerical modeling with the
one-minute OMNI data as the boundary condition show very good agreement with
the solar-wind temperature profiles obtained by Voyager-2. It is also
noteworthy that the numerical results with daily averaged OMNI data show a very
similar temperature profile, while the numerical runs with 27-day-averaged OMNI
data demonstrate the adiabatic behavior of the temperature.Comment: 12 pages, 7 figure
A Massive Jet Ejection Event from the Microquasar SS 433 Accompanying Rapid X-Ray Variability
Microquasars occasionally exhibit massive jet ejections which are distinct
from the continuous or quasi-continuous weak jet ejections. Because those
massive jet ejections are rare and short events, they have hardly been observed
in X-ray so far. In this paper, the first X-ray observation of a massive jet
ejection from the microquasar SS 433 with the Rossi X-ray Timing Explorer
(RXTE) is reported. SS 433 undergoing a massive ejection event shows a variety
of new phenomena including a QPO-like feature near 0.1 Hz, rapid time
variability, and shot-like activities. The shot-like activity may be caused by
the formation of a small plasma bullet. A massive jet may be consist of
thousands of those plasma bullets ejected from the binary system. The size,
mass, internal energy, and kinetic energy of the bullets and the massive jet
are estimated.Comment: 21 pages including 5 figures, submitted to Ap
Adsorption of Hexacontane on Hexagonal Boron Nitride
© 2018 American Chemical Society. We have investigated the adsorption of hexacontane (C60H122) on hexagonal boron nitride (hBN) using atomic force microscopy (AFM). The molecules can be deposited either by sublimation or from solution and form lamellar rows with dimensions of the order of 0.1-1 μm in three different rotational domains. High-resolution AFM images reveal that, similar to alkanes on graphite, the molecules are adsorbed parallel to the lattice vectors of hBN and we show using molecular mechanics that this corresponds to the lowest energy configuration. Lamellar rows with the same periodicity are observed even when several layers of hexacontane are deposited, although there is some orientational disorder in these multilayers. We also observe heat-induced modification of hexacontane, including recrystallization. We compare our results with recent X-ray studies of alkane adsorption on hBN and discuss the possible role of alkanes on steering molecular self-assembly on hBN
Experimental study of direct photon emission in K- --> pi- pi0 gamma decay using ISTRA+ detector
The branching ratio in the charged-pion kinetic energy region of 55 to 90 MeV
for the direct photon emission in the K- --> pi- pi0 gamma decay has been
measured using in-flight decays detected with the ISTRA+ setup operating in the
25 GeV/c negative secondary beam of the U-70 PS. The value
Br(DE)=[0.37+-0.39(stat)+-0.10(syst)]*10^(-5) obtained from the analysis of 930
completely reconstructed events is consistent with the average value of two
stopped-kaon experiments, but it differs by 2.5 standard deviations from the
average value of three in-flight-kaon experiments. The result is also compared
with recent theoretical predictions.Comment: 13 pages, 8 figure
Fe 3 O 4 nanoparticles for complex targeted delivery and boron neutron capture therapy
Magnetic Fe 3 O 4 nanoparticles (NPs) and their surface modification with therapeutic substances are of great interest, especially drug delivery for cancer therapy, including boron-neutron capture therapy (BNCT). In this paper, we present the results of boron-rich compound (carborane borate) attachment to previously aminated by (3-aminopropyl)-trimethoxysilane (APTMS) iron oxide NPs. Fourier transform infrared spectroscopy with Attenuated total reflectance accessory (ATR-FTIR) and energy-dispersive X-ray analysis confirmed the change of the element content of NPs after modification and formation of new bonds between Fe3O4 NPs and the attached molecules. Transmission (TEM) and scanning electron microscopy (SEM) showed Fe3O4 NPs’ average size of 18.9 nm. Phase parameters were studied by powder X-ray diffraction (XRD), and the magnetic behavior of Fe 3 O 4 NPs was elucidated by Mössbauer spectroscopy. The colloidal and chemical stability of NPs was studied using simulated body fluid (phosphate buffer-PBS). Modified NPs have shown excellent stability in PBS (pH = 7.4), characterized by XRD, Mössbauer spectroscopy, and dynamic light scattering (DLS). Biocompatibility was evaluated in-vitro using cultured mouse embryonic fibroblasts (MEFs). The results show us an increasing of IC50 from 0.110 mg/mL for Fe 3 O 4 NPs to 0.405 mg/mL for Fe 3 O 4 -Carborane NPs. The obtained data confirm the biocompatibility and stability of synthesized NPs and the potential to use them in BNCT. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant No AP05130947 “Setting the stage for boron neutron capture therapy of cancer in the Republic of Kazakhstan”) and Nazarbayev University “Social Policy Grant” (project title: “Research and development of the new Nano-Optical Sensor based on Polymer Optical Fiber for Near-Field Scanning Optical Microscopy”, PI: Kanat Dukenbayev). The authors also gratefully acknowledge the financial support of the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (NoK4-2018-036, P02-2017-2-4), implemented by a governmental degree dated 16th of March 2013, No 211. The work was partially supported by Act 211 Government of the Russian Federation, contract No 02.A03.21.0011. This work was partially supported by the Ministry of Education and Science of the Russian Federation (Government task in SUSU 5.5523.2017/8.9)
ГОСУДАРСТВЕННО-ЧАСТНОЕ ПАРТНЕРСТВО В АТОМНОЙ ЭНЕРГЕТИКЕ: ОПЫТ США
The public-private partnership (PPP) is a mechanism suited for running nuclear power plant (NPP) construction projects under conditions of limited state funding. The USA PPP experience with its 50-year tradition and real results achieved in the XXI century is undoubtedly the most mature in the global nuclear power industry: in 2008 the NPP construction project (Vogl, 3, 4) was launched in the USA being the first in 30 years. The PPP adaptation to new NPP projects is in demand both in Russia and abroad. The study of the American PPP practice in the nuclear industry includes the historical review, the comparative analysis of the liberalized and regulated energy markets as well as the survey of the legal and regulatory incentives that had an impact on the Vogl NPP project. The government at the federal and regional levels is taking the following measures to make the partnership attractive for all participants: the program of government guarantees for the US Department of Energy loans; the state system of the NPP owner liability insurance in the event of a nuclear accident; granting NPP owners a permission to include their NPP construction investments into tariff rates of energy consumers, etc. The study used the methods of analysis and synthesis, including the problem-chronological and logical analysis, as well as case studies. Based on the research findings, three fundamental components of a successful PPP for NPP projects were identified: guaranteed return on investments as a result of the stable and receptive market of energy sales at long-term fixed rates and stable costs of energy generation by nuclear power plants, actually independent of the uranium market situation; a solid national nuclear energy support policy implemented in specific support programs; a proactive approach of Vogl NPP shareholders. In the future, the analysis of the PPP experience of other countries in the nuclear industry (e. g., Finland, France, South Korea) will allow creation of a holistic PPP concept, which will make it possible to develop recommendations tailored to the specific features of individual NPP projects.Одним из перспективных механизмов реализации проектов сооружения АЭС в современных условиях ограниченности государственного финансирования является государственно-частное партнерство (ГЧП). Самым зрелым в мировой атомной отрасли является опыт США по ГЧП, который имеет 50-летние традиции и реальные результаты в XXI в.: в 2008 г. здесь впервые за 30 лет стартовал проект сооружения АЭС (Вогл, 3, 4). Адаптация ГЧП для реализации новых проектов АЭС востребована как в России, так и за рубежом. Изучение американской практики ГЧП в атомной энергетике охватывает исторический экскурс, сравнительный анализ либерализованных и регулируемых рынков электроэнергии, а также исследование правовых и регуляторных стимулов, оказавших влияние на проект АЭС Вогл. Правительство на федеральном и региональном уровнях предпринимает следующие меры для организации привлекательного для всех участников партнерства: программа госгарантий по кредитам Минэнерго США, государственная система страхования ответственности владельцев АЭС в случае ядерного инцидента, разрешение владельцам АЭС включать свои инвестиции на сооружение АЭС в тарифы энергопотребителей и др. В исследовании использованы методы анализа, в том числе проблемно-хронологического и логического, и синтеза, а также кейс-стадии. По итогам исследования выделены три основополагающих элемента успешного ГЧП для проектов АЭС: гарантии возврата инвестиций, благодаря стабильному и емкому рынку сбыта электроэнергии по долгосрочно фиксированным тарифам и стабильной стоимости генерации электроэнергии на АЭС, практически не зависящей от конъюнктуры уранового рынка; твердый курс национальной политики на поддержку развития атомной энергетики, реализованный в конкретных программах поддержки; проактивный подход акционеров АЭС Вогл. В перспективе анализ опыта других стран по ГЧП в атомной отрасли (например, Финляндии, Франции, Южной Кореи) позволит создать холистическую концепцию ГЧП, на основании которой можно разрабатывать рекомендации, адаптированные под особенности конкретных проектов АЭС
Роль ферментативного парапанкреатита в течении ранней фазы острого деструктивного панкреатита
Introduction. One of the most significant components of acute destructive pancreatitis (ADP) is enzymatic parapancreatitis (EP). The severity of the defeat of the retroperitoneal tissue from the early stages of the disease largely determines its course.The objectivewas to assess the features of the evolution of the pathological process in the retroperitoneal tissue in ADP and the effect of EP on the course of phase I of ADP.Methods and materials. 63 cases (ADP) without enzymatic peritonitis were analyzed. The average age of patients was (46.6±3.2) years (p≤0.05). The sum of points according to the express diagnostic scale of the SPb I. I. Dzhanelidze RIEM was (3.7±0.2) points (p≤0.05). The average time from the onset of the disease to the start of therapy was 2 days (from 7 to 1 day).Results. Types of EP at admission were distributed as follows: type B – 17.5 % (n=11) of cases, type C – 44.4 % (n=28) of cases, type D – 30.2 % (n=19) of cases, type E – 7.9 % (n=5) of cases. Spearman’s rank correlation coefficient for assessing the relationship between the severity of the condition and the type of parapancreatitis was 0.069. Infiltrative parapancreatitis (IP) was formed in 93.4 % of cases. The types of infiltrative parapancreatitis (pancreatic infiltrate) were distributed as follows: type A – 12.3 % (n=7) of cases, type B – 21.1 % (n=12) of cases, type C – 36.8 % (n=21) of cases, type D – 19.3 % (n=11) of cases, type E – 10.5 % (n=6) of cases. There was a pronounced relation between the severity of the patient’s condition and the prevalence of IP, the Spearman’s rank correlation coefficient was 0.82.Conclusions. EP is formed in most cases of acute destructive pancreatitis and is evolutionary. It has a significant effect on the severity of the patient’s condition and the course of acute destructive pancreatitis in the infiltrative phase of the disease.Введение. Одним из наиболее значимых компонентов острого деструктивного панкреатита (ОДП) является ферментативный парапанкреатит (ФП). Выраженность поражения забрюшинной клетчатки с ранних сроков заболевания в значимой мере определяет его течение.Цель – оценка особенностей эволюции патологического процесса в забрюшинной клетчатке при ОДП и влияние ФП на течение I фазы ОДП.Методы и материалы. Проанализированы 63 случая (ОДП) без явлений ферментативного перитонита. Средний воз- раст пациентов – (46,6±3,2) года (р≤0,05). Сумма баллов по экспресс шкале НИИ СП им. И. И. Джанелидзе составила (3,7±0,2) балла (р≤0,05). Средние сроки от начала заболевания до начала терапии составляли 2 суток (от 7 до 1 суток).Результаты. Типы ФП на момент поступления распределились следующим образом: тип В – 17,5 % (n=11) случаев, тип С – 44,4 % (n=28) случаев, тип D – 30,2 % (n=19) случаев, тип Е – 7,9 % (n=5) случаев. Критерий Спирмена при оценке связи тяжести состояния и типа парапанкреатита равнялся 0,069. Инфильтративный парапанкреатит (ИФ) сформировался в 93,4 % случаев. Типы инфильтративного парапанкреатита (панкреатического инфильтрата) распределились следующим образом: тип А – 12,3 % (n=7) случаев, тип B – 21,1 % (n=12) случаев, тип С – 36,8 % (n=21) случаев, тип D – 19,3 % (n=11) случаев, тип Е – 10,5 % (n=6) случаев. Отмечается выраженная связь тяжести состояния пациентов с распространенностью ИФ, корреляционный коэффициент Спирмена составил 0,82.Выводы. ФП формируется в большинстве случаев острого деструктивного панкреатита и носит эволюционный характер. Значимое влияние на тяжесть состояния пациента и течение острого деструктивного панкреатита оказывает в инфильтративную фазу заболевания
Degradation mechanism and way of surface protection of nickel nanostructures
Stability of nanomaterials during their life cycle is a crucial problem of modern nanoscience. In order to understand the processes, which are going in the nanostructures, the comprehensive study of the influence of media with different acidity on the nickel nanotubes morphology and structure was carried out. On the base of the analysis of nanotubes characteristics, sequential evolution of degradation stages involving the surface passivation, formation of point defects, pitting and destruction of nanotubes walls was determined. The results are of importance for the wide range of potential nickel nanostructures applications, which are associated with their using in real-life conditions. To improve Ni nanostructures stability, the possible ways of surface protections from the aggressive environment effect and the routes of nanostructures covering with gold, organosilicon compounds and polymer coatings were considered. Demonstrated approaches for nanostructures covering provide an opportunity of surface functionalization for attaching of different molecules. It is useful for targeted delivery of drugs and genes, biodetection, bioseparation and catalysis application. © 2018 Elsevier B.V
Comprehensive Study of Ni Nanotubes for Bioapplications: From Synthesis to Payloads Attaching
Due to the Ni nanotubes’ shape anisotropy, low specific density, large specific surface, and uniform magnetic field, they have been offered as carriers for targeted delivery of drug or protein and the process of their formation from synthesis stage to the stage of surface modification and protein attaching has been demonstrated. Some steps to hasten their biomedical application have been applied. First, to have full control over the carrier dimensions and structure parameters, electrodeposition method in pores of polyethylene terephthalate template has been applied. Second, to understand the scope of Ni nanostructures application, their degradation in media with different acidity has been studied. Third, to improve the biocompatibility and to make payloads attachment possible, nanotubes surface modification with organosilicon compound has been carried out. At last, the scheme of protein attaching to the nanostructure surface has been developed and the binding process was demonstrated as an example of the bovine serum albumin
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