Abstract
A method of protecting territories in a river basin during flash floods by creating a multi-stage system of intercepting flood control systems with temporarily filled reservoirs, with a ...phased construction of waterworks on side tributaries, including secondary ones. Using the computer programs developed by the authors, the operating modes of the hydroelectric system were simulated for a possible variant of placing their sections on the lateral tributary of the river: in the lower reaches- a traditional hydro system with an earth dam and a concrete spillway, including bottom holes and a surface spillway; upstream- an additional hydro system with a filtering dam made of gabion masonry, into which the missing accumulating volume is redistributed. The calculation of the social effect resulting from the considered method of protection by assessing the reduction of economic damage for settlements located in the downstream of the main flood control hydroelectric complex with participation in the cutoff of the flood peak of an additional temporarily filled reservoir located upstream of the river is performed.
Ionothermal synthesis of carbon nitride paved the way to a new structural allotrope—polytriazine imide. In this work, we screen available precursors for pristine polytriazine imides and for their ...graphitic analogs narrowing it to the melamine—urea mixture as the most promising starting material. Photocatalytic activity of materials verified in reaction of benzyl alcohol oxidation to benzaldehyde, which is known to be highly requested chemical with thousands of tons of annual production. Therefore "green" and selective route of production is highly desired. Developed PTI-LiCl was tested for selective photooxidation of benzyl alcohol to benzaldehyde, demonstrating precious conversion and selectivity rates—96.3% and 91.6%, respectively after 5 hours of UV irradiation. Detailed physical-chemical characterization revealed that PTI materials possessed more ordered and highly condensed structure which grant them improved photocatalytic properties in comparison to graphitic carbon nitride polymorph.
Graphical abstract
Graphical abstract represents two different lines of materials which are known to be various polymorphs of carbon nitride studied comparatively in the present work. One of them is convenient graphitized carbon nitride which is prepared from precursors (melamine, urea or thiourea) via the simple thermal treatment. Another line of materials are prepared via thermal treatment in the eutectic mixture of molten salts. The later line of materials is more active in selective photocatalytic oxidation of benzyl alcohol.
Particle identification system based on Focusing Aerogel RICH (FARICH) detector is considered as an option for the future experiments at the Super Charm-Tau Factory (Russia). We present the progress ...of FARICH R&D at the Budker Institute of Nuclear Physics. New samples of focusing 4-layer aerogels with maximal refractive index 1.065 were produced in 2020–2021. First beam test results with relativistic electrons demonstrate single photon resolution (SPR) of 9÷10mrad. According to simulation results, the aerogels with such SPR are able to provide μ/π-separation at the level of more than 3 standard deviations for tracks with momentum 1.5 GeV/c. The first version of electronics to readout SiPM arrays based on TDC implemented on FPGA (FPGA-TDC) was developed and manufactured.
To describe 10-year experience of treating the cicatricial tracheal stenosis (CTS) in a regional multi-field hospital.
There were 120 CTS patients aged 13-75 years. In 8 (6.7%) patients, CTS was ...combined with tracheoesophageal fistula (TPF). Post-intubation stenosis was diagnosed in 16 (13.3%) cases, post-tracheostomy - in 102 (85%) ones, post-traumatic - in 2 (1.7%) patients. CTS length ranged from 1.2 to 8 cm. Fifty (41.7%) patients had cervical CTS, 40 (33.3%) patients - cervico-thoracic tracheal stenosis, 11 (9.2%) patients - tracheal stenosis at the thoracic level. Nineteen (15.8%) patients had multifocal stenoses. We used endoscopic techniques, circular tracheal resection (CTR) and laryngotracheal reconstruction.
Postoperative mortality rate was 0.83%. CTR was performed in 33 patients, laryngotracheal reconstruction - 77, endoscopic stenting - 6 patients. In 4 cases, local CTS was eliminated by bougienage and argon plasma exposure. CTS was successfully disconnected with TEF using CRT in 3 cases, laryngotracheoplasty and stenting - in 5 cases. The fenestrated tracheal defect was closed by a three-layer autologous flap in 59 patients. Of these, autologous flap was reinforced with porous nickel-titanium implants in 17 patients. Postoperative complications after CRT occurred in 6 (16.7%) patients (anastomotic leakage - 2, anastomositis - 1, restenosis - 2). No patients died. Postoperative complications after laryngotracheal reconstruction were observed in 18 (23.4%) patients including 5 ones with restenosis who underwent CTR with a favorable outcome.
CTS treatment requires a multidisciplinary approach. Each surgery has certain indications and place in treatment algorithm. CTR is highly effective, but may be accompanied by complications associated with tracheal anastomosis. Decrease of postoperative morbidity will improve immediate and long-term results of CTS treatment. The chosen treatment algorithm ensured good and satisfactory results in 98% of patients.
Aerogel for FARICH detector Barnyakov, A.Yu; Barnyakov, M.Yu; Bobrovnikov, V.S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2014, Letnik:
766
Journal Article
Recenzirano
We present our current experience in preparation of focusing aerogels for the Focusing Aerogel RICH detector. Multilayer focusing aerogel tiles have been produced in Novosibirsk by a collaboration of ...the Budker Institute of Nuclear Physics and Boreskov Institute of Catalysis since 2004. We have obtained 2-3-4-layer blocks with the thickness of 30-45 mm. In 2012, the first samples of focusing blocks with continuous density (refractive index) gradient along thickness were produced. This technology can significantly reduce the contribution from the geometric factor of the radiator thickness to the resolution of the measured Cherenkov angle in the FARICH detector. The special installation was used for automatic control of reagents ratio during the synthesis process. The first samples were tested using the digital radiography method and on the electron beam with the FARICH prototype.
To analyze postoperative outcomes and perioperative management of patients with post-intensive care tracheal stenosis and previous COVID-19 pneumonia.
There were 8 patients with post-intensive care ...tracheal stenosis and previous COVID-19 pneumonia aged 34-61 years between January 2021 and April 2021. Lung damage CT-3 was observed in 2 (25%) patients, CT-4 - in 5 (62.5%) patients. In one case, COVID-19 pneumonia with lung damage CT-2 joined to acute cerebrovascular accident. Post-tracheostomy stenosis was detected in 7 (87.5%) cases, post-intubation stenosis - in 1 patient. Duration of invasive mechanical ventilation ranged from 5 to 130 days. In 75% of cases, tracheal stenosis was localized in the larynx and cervical trachea. Two patients admitted with tracheostomy. In one case, an extended tracheal stenosis was combined with atresia of infraglottic part of the larynx. One patient had tracheal stenosis combined with tracheoesophageal fistula (TEF). Length of tracheal stenosis was 15-45 mm. Tracheomalacia was observed in 4 (50%) patients. All patients had severe concomitant diseases.
To restore airway patency, we used circular tracheal resection with anastomosis, laryngotracheoplasty and endoscopic methods. Tracheal resection combined with TEF required circular tracheal resection with disconnection of fistula. Adequate breathing through the natural airways was restored in all patients. There was no postoperative mortality. Three patients with baseline tracheal stenosis had favorable postoperative outcomes after circular tracheal resection. Four patients are at the final stage of treatment after laryngotracheoplasty and tracheal stenting.
Patients after invasive mechanical ventilation for COVID-19 pneumonia are at high risk of cicatricial tracheal stenosis and require follow-up. Circular tracheal resection ensures early rehabilitation and favorable functional results. Laryngotracheoplasty is preferred if circular tracheal resection is impossible. This procedure ensures adequate debridement of tracheobronchial tree and respiratory support. Endoscopic measures are an alternative for open surgery, especially for intrathoracic tracheal stenosis and intractable tracheobronchitis.
The Super Charm–Tau (SCT) Factory is a proposed electron–positron collider in Novosibirsk with a peak luminosity of 1035cm−1s−1 operating in the energy range between 2and 6 GeV. The interaction ...region should be equipped by an excellent universal particle detector meeting the requirements of broad physics program of the experiment. Research and development for all detector subsystems is currently underway. Particle identification (PID) system of the detector is required to provide the state-of-the-art level of μ/π separation for the particle momenta up to 1.2GeV∕c. The following options for the PID system are considered in this paper: focusing aerogel ring imaging Cherenkov (FARICH) detector composed of 4-layer aerogel tiles, threshold Cherenkov counters based on aerogel shifter photomultiplier (ASHIPH), and time-of-flight (ToF) detector combined with the time-of-propagation (ToP) approach providing a time resolution better than 30ps. Assessment of the charged particle separation performance for these options based on simulation and prototype tests results is presented.
PID system based on focusing aerogel RICH for the super C-τ factory Barnyakov, A.Yu; Barnyakov, M.Yu; Boborovnikov, V.S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2020, Letnik:
952
Journal Article
Recenzirano
A high performance particle identification (PID) system is essential for the successful realization of the broad physics program at the future Super C-τ Factory in Novosibirsk. The main requirements ...for the PID system are as follows: good π/K-separation in the entire operational momentum range and good μ∕π-separation in the momentum range from 0.3 to 1.2 GeV/c. The RICH detector based on focusing aerogel radiator (FARICH) and position-sensitive photon detector meets all these requirements. The FARICH method is described, and the beam test results are presented. The FARICH system design outline for the Super C-τ Factory project is presented. Most promising photon detector options are considered.
•BaFe12O19 hexaferrites were obtained using two stages ceramic technology.•Different treatment conditions were the subject of study.•Density of pellets as a function of the applied pressure is ...presented.•Complex impedance spectra were measured in spectral range of 10−1–106 Hz.
BaFe12O19 were synthesized using usual ceramic technology in two stages. The structure and dielectric properties of the obtained samples after different processing conditions were the subject of study. At the final stage, the samples were thoroughly reground and pressed into pellets with different pressures. The unit cell parameters of the obtained samples were determined by X-ray diffraction method. The density of the sample pellets as a function of the applied pressure and sintering temperature was collected. The density of the initial sample pellets monotonously depends on the applied pressure. The density of the final sample pellets has a maximum at 1.055 GPa, after which a slight decrease was observed. Complex impedance spectra of all the obtained samples were measured in the frequency range of 10−1–106 Hz. Different treatment conditions result in two ranges of impedance spectrum. The impedance decreases with increasing processing pressure up to 1.055 GPa, above which, it starts gradually decrease. Complex spectra of impedance were fitted with a complex nonlinear least squares method based on the Levenberg-Marquardt minimization algorithm.
The paper presents a study of the electrical and dielectric properties of a single crystal of barium hexaferrite BaFe11.25Ti0.75O19. The single crystal was obtained by directional crystallization ...from solution (Czochralski method). Sodium carbonate (NaCO3) was used as a solvent. It was found that the electrical and dielectric properties in a crystal are strongly dependent on the crystallographic direction. The electrical conductivity differs by 8 orders of magnitude along and across the crystallographic C axis. It is also shown that in the direction of the crystallographic axis C (axis of easy magnetization), the conductivity depends on the value of the frequency. For further technology development it must be taken into account that not only chemical composition important for material but also direction of cutting for single crystal.
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•BaFe11·25Ti0·75O19 single crystal was grown by directional crystallization from solution.•Strong correlation between direction in crystal and electrical properties was observed.•The electrical conductivity differs by 8 orders of magnitude along and across the crystallographic C axis.
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