238 research outputs found
Elastic Pion Scattering on the Deuteron in a Multiple Scattering Model
Pion elastic scattering on deuterium is studied in the KMT multiple
scattering approach developed in momentum space. Using a Paris wave function
and the same methods and approximations as commonly used in pion scattering on
heavier nuclei excellent agreement with differential cross section data is
obtained for a wide range of pion energies. Only for MeV and very
backward angles, discrepancies appear that are reminiscent of disagreements in
pion scattering on He, H, and He. At low energies the second order
corrections have been included. Polarization observables are studied in detail.
While tensor analyzing powers are well reproduced, vector analyzing powers
exhibit dramatic discrepancies.Comment: 25 pages LATEX and 9 postscript figures in a self-extracting uufile
archiv
Electrode and redox potentials of molybdenum and stability of molybdenum chloro-species in alkali chloride melts
Molybdenum electrode and Mo(III)/(IV) redox potentials were measured in fused alkali chlorides. Experiments were performed in individual salts (LiCl, NaCl, KCl, RbCl and CsCl) and in several binary and ternary eutectic or low-melting mixtures between 633 and 1173 K (depending on the melting point of the solvent salt). Formal standard electrode potentials E∗ Mo/Mo(III) and redox potentials E∗ Mo(III)/Mo(IV) in respect to Cl-/Cl2 couple and Gibbs free energy change of formation of molybdenum(III) chloride in alkali chloride melts were calculated. Electronic absorption spectra of Mo(III) ions were recorded, and spectroscopic parameters of MoCl6 3- complex ions determined. High temperature spectroscopy measurements were used to study the stability of Mo(III) chloro-species in fused chlorides and the reaction rates of Mo(III) ions disproportionation were also determined. Diffusion coefficients of molybdenum ions in LiCl-KCl-CsCl and NaCl-CsCl eutectic based melts were determined from the results of electrochemical measurements. © The Author(s) 2017
A study of the biohydrometallurgical method for extracting gold from flotation tailings
This paper shows the results of the comparative study of efficiency of gold extraction methods from technogenic flotation tails by agitation cyanidation and biooxidation followed by leaching. A representative sample of flotation tails was taken at gold extraction plant of Altyntau Kokshetau LLP. Experimentally, an increase in the efficiency of leaching gold from flotation tails during preliminary bacterial oxidation was found. By biochemical leaching, 72 % was extracted, which is 7 % more than using expensive sodium peroxide and 10 % more than using the traditional method of cyanidation
Processing of vanadium and niobium electrodeposited from alkali chloride melts
The methods of hydrometallurgical treatment of cathodic deposits obtained by electrorefining vanadium and niobium metals in chloride melts were studied. The effectiveness of employing nitric acid was demonstrated. The optimal conditions of leaching trapped salt were determined: HNO3 concentration of 2.5 wt. % for vanadium and 5 wt. % for niobium; solid-to-liquid ratio 1:10 for both metals. The effect of increasing duration of a washing cycle on number of process stages was investigated. The methods of final washing and drying metallic powders were considered. ©The Electrochemical Society.Physical and Analytical Electrochemistry;Electrodeposition;Energy Technolog
Luminescence in anion-deficient hafnia nanotubes
Hafnia-based nanostructures and other high-k dielectrics are promising
wide-gap materials for developing new opto- and nanoelectronics devices. They
possess a unique combination of physical and chemical properties such as
insensitivity to electrical and optical degradation, radiation damage
stability, a high specific surface area, and an increased concentration of the
appropriate active electron-hole centers. The present paper aims to investigate
the structural, optical, and luminescent properties of anodized
non-stoichiometric nanotubes. As-grown amorphous hafnia nanotubes and
nanotubes annealed at 700{\deg}C with a monoclinic crystal lattice served as
samples. It has been shown that the bandgap for direct allowed
transitions amounts to eV for amorphous and eV for
monoclinic nanotubes. For the first time, we have studied the features of the
intrinsic cathodoluminescence and photoluminescence of the obtained nanotubular
structures with an atomic deficiency in the anion sublattice at
temperatures of 10 and 300 K. A broad emission band with a maximum of 2.3-2.4
eV has been revealed. We have also conducted an analysis of the kinetic
dependencies of the observed photoluminescence for synthesized samples
in the millisecond range at room temperature. It showed that there are several
types of optically active capture and emission centers based on vacancy states
in the and positions with different coordination numbers and
a varied number of localized charge carriers (, , and ). The
uncovered regularities can be used to optimize the functional characteristics
of developed-surface luminescent media based on nanotubular and nanoporous
modifications of hafnia.Comment: 15 pages, 6 figures, 3 tables, 50 reference
Three-Body approach to the K^- d Scattering Length in Particle Basis
We report on the first calculation of the scattering length A_{K^-d} based on
a relativistic three-body approach where the two-body input amplitudes coupled
to the Kbar N channels have been obtained with the chiral SU(3) constraint, but
with isospin symmetry breaking effects taken into account. Results are compared
with a recent calculation applying a similar set of two-body amplitudes,based
on the fixed center approximation, considered as a good approximation for a
loosely bound target, and for which we find significant deviations from the
exact three-body results. Effects of the hyperon-nucleon interaction, and
deuteron -wave component are also evaluated.Comment: 5 pages, Submitted to Phys. Rev.
Delta rho pi interaction leading to N* and Delta* resonances
We have performed a calculation for the three body system
by using the fixed center approximation to Faddeev equations, taking the
interaction between and , and, and and
from the chiral unitary approach. We find several peaks in the modulus
squared of the three-body scattering amplitude, indicating the existence of
resonances, which can be associated to known and and baryon states.Comment: Presented at the 21st European Conference on Few-Body Problems in
Physics, Salamanca, Spain, 30 August - 3 September 201
Super-selective prostatic arteries embolization in patients with benign prostate hyperplasia: prevention and treatment of complications
Introduction. Super-selective prostatic arteries embolization (PAE) is a modern minimally invasive surgical method for the treatment of benign prostatic hyperplasia (BPH). PAE is included in the Russian clinical guidelines for the BPH treatment and approved for use in the United States and European countries.Purpose of the study. To analyze the most common PAE-associated complications and to develop preventive arrangements.Materials and methods. During the period from 2013 to 2020, PAE as the main method of BPH treatment was used in 168 patients with an average age of 69.3 ± 8.1 (53-82) years. All patients underwent two-day antibiotic prophylaxis before the operation and lasted 7-10 days. For catheterization of the prostatic arteries, 2.0-2.8 Fr microcatheters and 4-5 Fr microconductors were used. For embolization, hydrogel microspheres with a diameter of 100-300 µm and 300-500 µm were used, as well as poly polyvinyl alcohol (PVA) microparticles with a diameter of 100-500 µm.Results. Bilateral PAE was successfully performed in 146 cases; unilateral PAE was performed in 22 patients due to anatomical features. Seventeen (10.1%) PAE from the orifice, super-selective PAE was performed in 67 (39.9%) cases, the PErFecTED embolization was performed in 84 (50.0%) patients. The most common complication was acute urinary retention (AUR) in 28 (16.6%) patients: trocar cystostomy was required in 11 (6.5%) patients, AUR was resolved using conservative therapy in 17 (10.2%) patients. In 23 (14.2%) cases, complications associated with unintentional embolization of the anastomoses of the prostate arteries were identified: rectal pain and/or the appearance of blood in the stool in 19 (11.3%) patients, the appearance of trophic ulcers on the glans penis in 5 (2.8%) patients. In addition, several adverse events that were not complications were noted: postembolization syndrome in 50 (29.7%) patients, and worsening of LUTS in 41 (24.4%) patients. Seven (4.1%) patients had acute epididymitis; 4 (2.4%) patients had a hematoma at the puncture site.Conclusion. PAE can cause a limited number of complications. It is necessary to unify the system for reporting PAE complications. Antibiotic prophylaxis is recommended. The use of visualization and X-ray navigation methods make it possible to make the PAE safer. The PErFecTED technique in combination with small particle sizes increases the risk of complications. The surgeon's experience and proficiency in special surgical techniques are essential. The transradial approach is promising, but further observation and an increase in patient samples are required. The question of choosing the optimal embolization drug continues to be relevant
Quasi-free Photoproduction from the Bound Nucleon
Differential cross-sections for quasi-free photoproduction from the
proton and neutron bound in the deuteron have been measured for MeV at usind the Glasgow photon
tagger at MAMI, the Mainz 48 cm 64 cm NaI(Tl) photon
detector and the G\"ottingen SENECA recoil detector. For the proton
measurements made with both liquid deuterium and liquid hydrogen targets allow
direct comparison of "free" photoproduction cross-sections as extracted
from the bound proton data with experimental free cross sections which are
found to be in reasonable agreement below 320 MeV. At higher energies the
"free" cross sections extracted from quasifree data are significantly smaller
than the experimental free cross sections and theoretical predictions based on
multipole analysis. For the first time, "free" neutron cross sections have been
extracted in the -region. They are also in agreement with the
predictions from multipole analysis up to 320 MeV and significantly smaller at
higher photon energies
Types of the prostate blood supply during super-selective embolization of prostatic arteries
Introduction. Pelvic arteries have various anatomy and anastomoses with other branches of the internal iliac artery (IIA). This explains the technical complexity of identification and catheterization of prostatic arteries (PA), as well as the possibility of complications associated with non-target embolization of prostatic artery anastomoses.Purpose of the study. To analyze the most common variants of prostate blood supply and evaluate the effectiveness of methods for identifying prostatic arteries.Materials and methods. The study included 168 patients treated from 2013 to 2021. For catheterization of the prostatic arteries, 4 – 5 Fr microconductors and 2 – 2.8 Fr microcatheters were used. For embolization, hydrogel microspheres with a diameter of 100 – 300 µm and 300 – 500 µm were used, as well as PVA microparticles with a diameter of 100 – 500 µm. Preoperatively multi-sliced computed tomography (MSCT) angiography of the pelvic organs was performed to determine the type of prostatic angioarchitectonics.Results. The use of preoperative MSCT angiography in combination with intraoperative digital subtraction angiography made it possible to determine the variations of prostatic artery divergence and identify their anastomoses in 100% of patients (336 pelvic sides). One prostatic artery was detected in 91.4% (307) of the pelvic sides. two independent pAs in 8.6% (29) of cases. Symmetrical anatomy of the prostatic arteries on both sides was revealed in 14.3% (24) patients, the remaining 85.7% (144) patients showed asymmetry on both sides. The absence of prostatic arteries anastomoses was detected in 75.5% (254) of the pelvic sides, and in 24.4% (82) of the pelvic sides, anastomoses were detected. Interlobar intraprostatic anastomoses were found in 10.1% (34) of the pelvic sides, communication with a. dorsalis penis was detected in 8% (27) of cases, with rectal arteries in 5.3% (18) of the pelvic sides and with urinary bladder arteries in 3.6% (12) of cases. Based on the analysis of the small pelvis angioarchitectonics in 168 patients, an anatomical classification of the prostatic arteries anatomy was proposed.Conclusion. Super-selective embolization of the prostatic arteries is a contemporary minimally invasive method of prostatic hyperplasia treatment with a high safety profile. The pelvic arteries have extremely various anatomy, as well as anastomoses with other branches of the internal iliac artery, which complicates the implementation of super-selective embolization of prostatic arteries. The combination of preoperative MSCT and intraoperative digital subtraction angiography makes it possible to identify the prostatic artery and its anastomoses in most cases
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