•Microplasma process is developed for continuous, one pot synthesis of iron oxide NPs.•A micro reactor system governed by modular design, safety considerations and broad operation space is ...demonstrated.•The obtained NPs are extremely small, uniform and have polycrystalline nature.•Study of the complex plasma-chemical kinetics taking place in micro reactor.•Possible mechanisms for ferrocene decomposition in microdischarges are proposed.
Microplasma is a novel technology for functional nanomaterial synthesis. In this research, iron oxide nanoparticles are successfully synthesized by a home-built microplasma setup. The setup is specially designed with overall safety considerations and broad operation space, including a smart micro reactor system which allows for flexible process control, easy assembling and direct product collection. The atmospheric pressure gas discharge was sustained in Ar flow with addition of ferrocene vapors as a precursor. The influence of the gas temperature and power dissipated in the discharge on the dissociation process is investigated. Optical emission spectroscopy (OES) is applied to study the impact of discharge parameters on plasma characteristics and possible mechanism of the ferrocene dissociation. The obtained products are characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDX), transmission electron microscopy (TEM), high resolution TEM (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Results show that nanometer-sized and well-dispersed iron oxide nanoparticles with polycrystalline nature can be produced by the atmospheric pressure microplasma setup. The increase of temperature and power helps to enhance the precursor dissociation rate. However, it also contributes to the production of larger sized nanoparticles with higher agglomeration degree. Based on experimental data, simplified modeling as well as relevant information from literature, we proposed possible mechanisms for ferrocene decomposition.
DANSS is a highly segmented 1 m3 plastic scintillator detector. Its 2500 one meter long scintillator strips have a Gd-loaded reflective cover. The DANSS detector is placed under an industrial 3.1 ...GWth reactor of the Kalinin Nuclear Power Plant 350 km NW from Moscow. The distance to the core is varied on-line from 10.7 m to 12.7 m. The reactor building provides about 50 m water-equivalent shielding against the cosmic background. DANSS detects almost 5000 ν˜e per day at the closest position with the cosmic background less than 3%. The inverse beta decay process is used to detect ν˜e. Sterile neutrinos are searched for assuming the 4ν model (3 active and 1 sterile ν). The exclusion area in the Δm142,sin22θ14 plane is obtained using a ratio of positron energy spectra collected at different distances. Therefore results do not depend on the shape and normalization of the reactor ν˜e spectrum, as well as on the detector efficiency. Results are based on 966 thousand antineutrino events collected at three different distances from the reactor core. The excluded area covers a wide range of the sterile neutrino parameters up to sin22θ14<0.01 in the most sensitive region.
Alumina with an urchin-like morphology has been synthesized from Al
2
(SO
4
)
3
/CO(NH
2
)
2
/H
2
O/isopropanol mixture via hydrothermal route followed by calcination. Raman spectra and SEM images ...have shown the urchin-like structure to be formed of γ-AlOOH phase with the component ratio Al
3+
/CO(NH
2
)
2
/H
2
O = 1:(2–3):(100–200). The increase in CO(NH
2
)
2
content has resulted in the formation of needle-like crystals of NH
4
Al(OH)
2
CO
3
. Structural transformations of alumina during hydrothermal synthesis have been investigated by SEM and TEM methods. The 5–10 μm urchin-like alumina particles have been found to be composed of 100–200-nm-thick sheets. The alumina samples have been studied by low-temperature nitrogen adsorption method. The adsorption–desorption isotherms and pore size distributions have shown that pore structure of the urchin-like alumina is formed by the slit pores with two open ends. It has been found that after treatment with chlorosilanes the surface of the urchin-like alumina becomes superhydrophobic, the average contact and sliding angle values being 154° and 5°, respectively. Addition of 5 wt% of the hydrophobized urchin-like alumina particles to the model fire-extinguishing powder has made the powder hydrophobic, the average contact angle being increased up to 151°. Introduction of 5 wt% of the hydrophobized urchin-like alumina particles to ammonium dihydrophosphate has resulted in a decrease in the cohesion strength for ammonium dihydrophosphate fire-extinguishing powder from 0.415 to 0.104 kPa. The hydrophobized urchin-like alumina particles can be used as functional additives to the fire-extinguishing powders for the improved flowability and water repellency to be achieved.
It is shown by computer modeling that at feed pipe and top drain pipe diameters to cylindrical hydrocyclone body part diameter ratio of 0.41 hydraulic losses are minimized if volume flow rates of the ...suspension separated in the hydrocyclones are equal. Hydrocyclone designing with appropriate ratios of the geometric parameters makes it possible to reduce their overall dimensions without decrease of the prescribed separation factors and volume throughput, but with some increase of power consumption. Equations are derived for calculating volume throughput and separation boundary grain of hydrocyclones with geometric and operating parameters varying in a wide range.
The effect of quantum corrections to the energy distribution function of light particles, which are associated with quantum indeterminacy due to their frequent collisions with heavy buffer gas ...particles, is investigated theoretically for CO molecules and He atoms as an example. We analyze the effect of quantum corrections to relaxation rate constants of vibrationally excited CO molecules on helium atoms depending on the gas mixture composition and the gas density and pressure. The effect of quantum corrections on the vibrational relaxation time is calculated using the model of level-by-level vibrational kinetics. The propositions concerning the experimental verification of this new effect that has been predicted theoretically are formulated.
The DANSS detector (Alekseev et al. in JINST 11:P11011, 2016) is located directly below a commercial reactor core at the Kalinin Nuclear Power Plant. Such a position provides an overburden about 50 ...m.w.e. in vertical direction. In terms of the cosmic rays it occupies an intermediate position between surface and underground detectors. The sensitive volume of the detector is a cubic meter of plastic scintillator with fine segmentation and combined PMT and SiPM readout, surrounded by multilayer passive and active shielding. The detector can reconstruct muon tracks passing through its sensitive volume. The main physics goal of the DANSS experiment implies the antineutrino spectra measurements at various distances from the source. This is achieved by means of a lifting platform so that the data is taken in three positions – 10.9, 11.9 and 12.9 meters from the reactor core. The muon data were collected for nearly four calendar years. The overburden parameters
⟨
E
thr
cos
θ
⟩
and
⟨
E
thr
⟩
, as well as the temperature and barometric correlation coefficients are evaluated separately for the three detector positions and, in each position, in three ranges of the zenith angle – for nearly vertical muons with
cos
θ
>
0.9
, for nearly horizontal muons with
cos
θ
<
0.36
, and for the whole upper hemisphere.
The article continues the discussion on the topical issue of administrative discretion for Russian administrative-legal theory and legal practice, organized by the editors of the journal “Siberian ...Law Review” on the pages of two previous issues of the journal with the participation of P. P. Serkov and Yu. P. Solovey. The Author focuses on the state of the modern domestic doctrine of administrative discretion, the contribution of Russian legal scholars to its development, the need and possibility (including criteria and limits) of delimiting administrative discretion from other types of discretion. It is proved that the Russian jurisprudence demonstrates, contrary to the assertions of some experts, not confusion in the face of the problematic category of discretion, but ontological and methodological certainty, although sometimes reaching extremes. At the same time, there is no single Russian doctrine of discretion, there are many such doctrines, and some scholars have the right to claim that specific doctrines are associated with their names. The Author draws attention to the fact that discretion in general and administrative discretion in particular are interdisciplinary (interscientific) categories, so they must first of all be rid of the semantic and meaningful “layers” of other sciences. The sooner a pure theory of discretion appears, the more mistakes and risks will be insured against by legal science and law enforcement practice. In order to avoid terminological confusion and preserve the subject matter of the study, it is absolutely important to distinguishfour concepts: 1) administrative discretion; 2) judicial control over administrative discretion; 3) judicial discretion; 4) judicial discretion in the exercise of judicial control over administrative discretion. These concepts have a certain connection with each other, however, they designate different (partly even by their branch affiliation) categories, phenomena, processes and institutions. As a conclusion, it is indicated that the motives of each discretionary decision of the public administration must sooner or later (better sooner than later) be made public. To make this a reality, legal science needs to develop and offer effective legal guarantees for ensuring the rights of citizens and their associations when public authorities exercise their discretionary powers.
The effect of temperature and pressure on the nucleation of the vapor phase and the velocity of the vapor front in the initial stage of activated boiling-up of n-pentane on the surface of a quartz ...fiber was studied. Using a developed approach combining the “pump-probe” and laser Doppler velocimetry methods, this velocity was tracked in the course of sequential change in the degree of superheating with respect to the liquid–vapor equilibrium line. The studied interval according to the degree of superheating was 40–100 °C (at atmospheric pressure). In order to spatiotemporally localize the process, the activation of boiling-up at the end of the light guide was applied using a short nanosecond laser pulse. A spatial locality of measurements was achieved in units of micrometers, along with a time localization at the level of nanoseconds. An increase in temperature at a given pressure was found to lead to an increase in the speed of the transition process with a coefficient of about 0.2 m/s per degree, while an increase in pressure at a given temperature leads to a decrease in the transition process speed with a coefficient of 25.8 m/s per megapascal. The advancement of the vapor front velocity measurements to sub-microsecond intervals from the first signs of boiling-up did not confirm the existence of a Rayleigh expansion stage with a constant velocity.
Abstract
For the specific mode of pulse heating of a wire probe immersed in a test liquid (saturated hydrocarbon), the effect of enhancement of the heat transfer through the probe surface has been ...revealed. The characteristic heating time is from 10 to 20 ms. The objects of research are
n
-hexane,
n
-decane, and
n
-hexadecane. It is shown that the addition of 0.003% water increases the heat transfer to 10% in the course of approaching the boiling-up temperature of liquid. Simulation of the experimental conditions shows the possibility of microconvection in the most heated boundary layer of a liquid about 10 μm thick.
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