Formation of Spherical Nanoparticles BaTiO3 by Peroxide Method

Structure of barium titanate particles obtained by peroxide method was studied by SEM, X-ray phase analysis, IR spectroscopy and Raman scattering. Found, that particles have preferably a spherical shape with a diameter of 20-200 nm and contain both cubic and tetragonal phases. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3365

Piezoelectric Properties of BaTiO3 Nanoparticles with Surfaces Modified by Hydroxyl Groups

Piezoelectric properties of nanoparticles BaTiO3 with spherical shape, diameter of 20-200 nm, the sur-face-modified hydroxyl (-OH) groups studied by piezoelectric force microscopy. Measured value of piezoe-lectric coefficient d*33=27 pm/V, which is close to the value obtained for the 100 nm particles BaTiO3. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3612

Позднее обнаружение туберкулеза легких на современном этапе

Institute of phthisiopneumology „Chiril Draganiuc”, Congresul III al Medicilor de Familie din Republica Moldova 17–18 mai, 2012, Chişinău, Republica MoldovaIntroducere În prezent depistarea tuberculozei se efectuează, de regulă, la simptomatici, prin adresare. S-a majorat numărul cazurilor de tuberculoză tardiv depistată, care influenţează negativ prognoza bolii. În acelaşi timp, nu este determinată definiţia contemporană „depistarea tuberculozei tardive”. Nu este clar rolul acestor cazuri în insuccesul tratamentului şi mortalitatea prin tuberculoză. Este necesar de determinat frecvenţa cazurilor tardiv depistate de tuberculoză, ineficacitatea tratamentului şi de elaborat un sistem perfecţionat în depistarea şi organizarea tratamentului. Metodele perfecţionate ale depistării bolnavilor cu tuberculoză pulmonară, reducerea erorilor în diagnosticarea şi organizarea chimioterapiei adecvate vor permite ridicarea eficacităţii tratamentului şi micşorarea mortalităţii prin tuberculoză. Material şi metode Au fost examinaţi 157 de bolnavi tardiv depistaţi din trei teritorii rurale: raionul Orhei – 64, Călăraşi – 46, Ialoveni – 47. În grupul de comparaţie au fost examinaţi 132 de bolnavi depistaţi la timp din aceleaşi teritorii rurale: raionul Orhei – 37, Călăraşi – 34, Ialoveni – 61. Metodele de cercetare au fost tradiţionale pentru practica ftiziologică: examinare clinică, metode imagistice (microradiofotografia, radiografia, tomografia), examinări microbiologice (bacterioscopia, însămânţarea, BACTEC), testarea la tuberculină, metode instrumentale, cercetări morfopatologice. Rezultate obţinute şi discuţii Din 267 de bolnavi prim depistaţi din teritoriile susnumite, tardiv depistaţi au fost 58,8%. În raionul Orhei acest număr a alcătuit 62,7% (64 din 102), în raionul Călăraşi – 56,8% (46 din 81), în raionul Ialoveni – 56,0% (47 din 84). Printre bolnavi tardiv depistaţi, bărbaţi au fost 77,7%, femei – 22,3%. Printre bolnavii depistaţi la timp, bărbaţi au fost 64,4%, femei – 35,6%. În grupul bolnavilor depistaţi la timp femeile au fost de 1,6 ori mai multe. Majoritatea bolnavilor în ambele grupuri erau în vârstă aptă de muncă. Din numărul total al bolnavilor tardiv depistaţi 120 (76,4%) n-au fost angajaţi în câmpul muncii, printre bolnavii depistaţi la timp – 84 (63,5%), de 1,2 ori mai mic. A fost determinat modul de îndreptare a bolnavilor tardiv depistaţi şi depistaţi la timp în cabinetele antituberculoase. Majoritatea bolnavilor tardiv depistaţi (85,3%) au fost depistaţi prin adresare (adresarea la medicul de familie, alţi specialişti, adresarea directă). Printre bolnavii depistaţi la timp acest indicator a alcătuit 49,2%, de 1,7 ori mai mic. Forma clinică de bază printre bolnavii tardiv depistaţi (68,5%) a fost tuberculoza infiltrativă cu distrucţie. Din 106 bolnavi cu tuberculoză infiltrativă distructivă 85 (80,2%) au avut distrucţie monolaterală, 21 (19,8%) – bilaterală. Din numărul total (157) al bolnavilor examinaţi 126 (80,3%) erau baciliferi, 15 (9,5%) – n-au eliminat micobacterii de tuberculoză, 16 (10,2%) – n-au fost examinaţi (diagnosticaţi postmortem). Din numărul bolnavilor tardiv depistaţi la 38 (30,2%) a fost determinată multidrogrezistenţa. Forma clinică de bază (68,5%) la bolnavii depistaţi la timp a fost tuberculoza infiltrativă fără distrucţie. Din numărul total (132) al bolnavilor examinaţi 69 (52,3%) erau baciliferi. Din ei la 7 (10,1%) bolnavi a fost determinată multidrogrezistenţa. Aşadar, numărul eliminatorilor de bacili printre bolnavii tardiv depistaţi era de 1,5 ori mai mare decât printre bolnavii depistaţi la timp. Numărul baciliferilor cu multidrogrezistenţă printre bolnavii tardiv depistaţi era de 3,0 ori mai mare decât printre bolnavii depistaţi la timp. Au fost evaluate rezultatele supravegherii bolnavilor tardiv depistaţi în termenul 6–12 luni. Acest termen este insuficient pentru concluzii argumentate în eficacitatea tratamentului. La 71 de bolnavi lipsesc datele despre tratament. În acelaşi timp, printre 86 de bolnavi (care au avut datele despre tratament) efectul pozitiv a avut loc numai la 24 (27,9%) dintre ei, acest rezultat fiind nesatisfăcător, deoarece eficacitatea tratamentului trebuie să fie de 85% conform recomandărilor OMS. La 55 de bolnavi depistaţi la timp datele despre tratament lipsesc. În acelaşi timp printre 77 de bolnavi, efectul pozitiv a fost la 61 (79,2%) ceea ce constituie un rezultat destul de satisfăcător. Printre bolnavii tardiv depistaţi acest indicator era de 2,8 ori mai jos. Concluzii Bolnavii tardiv depistaţi alcătuiesc o parte destul de impunătoare printre contingentele de bolnavi cu tuberculoză pulmonară şi, în ansamblu, pondera lor în teritoriile examinate ajunge la 58,8% şi deviază de la 56,0% până la 62,7%, ceea ce este legat de organizarea calităţii depistării tuberculozei. Bolnavii de tuberculoză tardiv depistaţi, după statutul lor reprezintă un contingent foarte complicat în plan social şi medical, în comparaţie cu bolnavii depistaţi la timp. Posibilitatea efectului pozitiv după tratamentul acestor bolnavi este mai joasă, decât la bolnavii depistaţi la timp. Pentru îmbunătăţirea eficacităţii tratamentului bolnavilor de tuberculoză este necesar de ridicat nivelul depistării precoce

Dielectric and magnetic responses in nanocrystalline BaTiO3

This work was supported by Russian Foundation for Basic Research (Research Project No.18-52-00039 Bel_a)

Spectacular enhancement of the thermal and photochemical stability of mapbi3 perovskite films using functionalized tetraazaadamantane as a molecular modifier

Perovskite solar cells represent a highly promising third-generation photovoltaic tech-nology. However, their practical implementation is hindered by low device operational stability, mostly related to facile degradation of the absorber materials under exposure to light and elevated temperatures. Improving the intrinsic stability of complex lead halides is a big scientific challenge, which might be addressed using various “molecular modifiers”. These modifiers are usually rep-resented by some additives undergoing strong interactions with the perovskite absorber material, resulting in enhanced solar cell efficiency and/or operational stability. Herein, we present a deriva-tive of 1,4,6,10-tetraazaadamantane, NAdCl, as a promising molecular modifier for lead halide perovskites. NAdCl spectacularly improved both the thermal and photochemical stability of methy-lammonium lead iodide (MAPbI3 ) films and, most importantly, prevented the formation of metallic lead Pb0 as a photolysis product. NAdCl improves the electronic quality of perovskite films by healing the traps for charge carriers. Furthermore, it strongly interacts with the perovskite framework and most likely stabilizes undercoordinated Pb2+ ions, which are responsible for Pb0 formation under light exposure. The obtained results feature 1,4,6,10-tetraazaadamantane derivatives as highly promising molecular modifiers that might help to improve the operational lifetime of perovskite solar cells and facilitate the practical implementation of this photovoltaic technology. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.This work was supported by Russian Science Foundation (project No. 19-73-30020). The XPS measurements were supported by the Ministry of Education and Science of the Russian Federation (project FEUZ-2020-0060), Theme ‘Electron’, no. AAAA-A18-118020190098-5 and Russian Foundation for Basic Research (project No. 21-52-52002)

Eight exoplanet candidates in SAO survey

Here we present eight new candidates for exoplanets detected by the transit method at the Special Astrophysical Observatory of the Russian Academy of Sciences. Photometric observations were performed with a 50-cm robotic telescope during the second half of 2020. We detected transits with depths of $\Delta m = 0.056-0.173^m$ and periods $P = 18.8^h-8.3^d$ in the light curves of stars with magnitudes of $m = 14.3-18.8^m$. All considered stars are classified as dwarfs with radii of $R_* = 0.4-0.6 R_{sun}$ (with the uncertainty for one star up to $1.1 R_{sun}$). We estimated the candidate radii (all are greater than 1.4 times the Jovian radius), semi-major axes of their orbits ($0.012-0.035 AU$), and other orbital parameters by modelling. We report the light curves with transits for two stars obtained in 2022 based on individual observations.Comment: 16 pages, 14 figures, 3 table

The Outer Tracker Detector of the HERA-B Experiment Part I: Detector

The HERA-B Outer Tracker is a large system of planar drift chambers with about 113000 read-out channels. Its inner part has been designed to be exposed to a particle flux of up to 2.10^5 cm^-2 s^-1, thus coping with conditions similar to those expected for future hadron collider experiments. 13 superlayers, each consisting of two individual chambers, have been assembled and installed in the experiment. The stereo layers inside each chamber are composed of honeycomb drift tube modules with 5 and 10 mm diameter cells. Chamber aging is prevented by coating the cathode foils with thin layers of copper and gold, together with a proper drift gas choice. Longitudinal wire segmentation is used to limit the occupancy in the most irradiated detector regions to about 20 %. The production of 978 modules was distributed among six different laboratories and took 15 months. For all materials in the fiducial region of the detector good compromises of stability versus thickness were found. A closed-loop gas system supplies the Ar/CF4/CO2 gas mixture to all chambers. The successful operation of the HERA-B Outer Tracker shows that a large tracker can be efficiently built and safely operated under huge radiation load at a hadron collider.Comment: 28 pages, 14 figure

Aging Studies for the Large Honeycomb Drift Tube System of the Outer Tracker of HERA-B

The HERA-B Outer Tracker consists of drift tubes folded from polycarbonate foil and is operated with Ar/CF4/CO2 as drift gas. The detector has to stand radiation levels which are similar to LHC conditions. The first prototypes exposed to radiation in HERA-B suffered severe radiation damage due to the development of self-sustaining currents (Malter effect). In a subsequent extended R&D program major changes to the original concept for the drift tubes (surface conductivity, drift gas, production materials) have been developed and validated for use in harsh radiation environments. In the test program various aging effects (like Malter currents, gain loss due to anode aging and etching of the anode gold surface) have been observed and cures by tuning of operation parameters have been developed.Comment: 14 pages, 6 figures, to be published in the Proceedings of the International Workshop On Aging Phenomena In Gaseous Detectors, 2-5 Oct 2001, Hamburg, German

Elliptic flow from two- and four-particle correlations in Au + Au collisions at sqrt{s_{NN}} = 130 GeV

Elliptic flow holds much promise for studying the early-time thermalization attained in ultrarelativistic nuclear collisions. Flow measurements also provide a means of distinguishing between hydrodynamic models and calculations which approach the low density (dilute gas) limit. Among the effects that can complicate the interpretation of elliptic flow measurements are azimuthal correlations that are unrelated to the reaction plane (non-flow correlations). Using data for Au + Au collisions at sqrt{s_{NN}} = 130 GeV from the STAR TPC, it is found that four-particle correlation analyses can reliably separate flow and non-flow correlation signals. The latter account for on average about 15% of the observed second-harmonic azimuthal correlation, with the largest relative contribution for the most peripheral and the most central collisions. The results are also corrected for the effect of flow variations within centrality bins. This effect is negligible for all but the most central bin, where the correction to the elliptic flow is about a factor of two. A simple new method for two-particle flow analysis based on scalar products is described. An analysis based on the distribution of the magnitude of the flow vector is also described.Comment: minor text change

Azimuthal anisotropy and correlations in the hard scattering regime at RHIC

Azimuthal anisotropy ($v_2$) and two-particle angular correlations of high $p_T$ charged hadrons have been measured in Au+Au collisions at $\sqrt{s_{NN}}$=130 GeV for transverse momenta up to 6 GeV/c, where hard processes are expected to contribute significantly. The two-particle angular correlations exhibit elliptic flow and a structure suggestive of fragmentation of high $p_T$ partons. The monotonic rise of $v_2(p_T)$ for $p_T<2$ GeV/c is consistent with collective hydrodynamical flow calculations. At \pT>3 GeV/c a saturation of $v_2$ is observed which persists up to $p_T=6$ GeV/c.Comment: As publishe