Optical study of the polar BM CrB in low accretion state

This paper presents a spectral and photometric study of the poorly studied polar BM CrB. Three states of the polar brightness and signs of transition from one-pole to two-pole accretion mode were found by an analysis of ZTF data. It is shown that the transition from the low state to the high state changes the longitude of the main accretion spot (by $\approx 17^{\circ}$) and increases its elongation (by $\approx 10^{\circ}$). The spectra contain Zeeman absorptions of the H$\alpha$ line which are formed at a magnetic field strength of $15.5\pm1$ MG. These absorptions are likely produced by a cold halo extending from the accretion spot at $\approx {^1/_4}$ of the white dwarf radius. Modeling of the behavior of the H$\alpha$ emission line shows that the main source of emission is the part of the accretion stream near the Lagrangian point L$_1$, which is periodically eclipsed by the donor star. The spectra exhibit a cyclotron component formed in the accretion spot. Its modeling by a simple accretion spot model gives constraints on the magnetic field strength $B=15-40$ MG and the temperature $T_e\gtrsim15$ keV

Reactive magnetron plasma modification of electrospun PLLA scaffolds with incorporated chloramphenicol for controlled drug release

Surface modification with the plasma of the direct current reactive magnetron sputtering has demonstrated its efficacy as a tool for enhancing the biocompatibility of polymeric electrospun scaffolds. Improvement of the surface wettability of materials with water, as well as the formation of active chemical bonds in the near-surface layers, are the main reasons for the described effect. These surface effects are also known to increase the release rate of drugs incorporated in fibers. Herein, we investigated the effect of plasma modification on the chloramphenicol release from electrospun poly (lactic acid) fibrous scaffolds. Scaffolds with high—50 wt./wt.%—drug content were obtained. It was shown that plasma modification leads to an increase in the drug release rate and drug diffusion coefficient, while not deteriorating surface morphology and mechanical properties of scaffolds. The materials’ antibacterial activity was observed to increase in the first day of the experiment, while remaining on the same level as the unmodified group during the next six days. The proposed technique for modifying the surface of scaffolds will be useful for obtaining drug delivery systems with controlled accelerated release, which can expand the possibilities of local applications of antibiotics and other drugs

Вивчення впливу комбінованої дії фотосенсибілізатора і низькоінтенсивного лазерного випромінювання на кількісний склад мікрофлори зубного нальоту

The effect of low-intensity laser radiation (LILR) on the background of a photosensitizer (ethacridine lactate) on selective elimination of pathogenic and conditionally pathogenic microorganisms has been studied. Taking into account antiseptic properties of ethacridine lactate the maximally possible time of influence of ethacridine lactate as a photosensitizer should be set. It has been found that after the influence of rivanol (ethacridine lactate) within 1.5-3 minutes the bactericidal action on microorganisms is observed. The effect of antiseptic in the interval from 30 to 60 seconds was not accompanied with the expressed quantitative change of the microbial population. The second stage of the research was identification of microorganisms sensitivity to various concentrations of the photosensitizer. As a photosensitizer the aqueous solution of ethacridine lactate in the concentrations of 0.1; 0.05; 0.01% was used. The results obtained allow to conclude that the concentration of 0.1% solution of ethacridine lactate increases the sensitivity of microorganisms to the effects of low-intensity laser radiation. During the experiment the combined impact of the antimicrobial activity of 0.1% solution of ethacridine lactate and blue spectrum laser radiation has been determined; it is manifested by decrease in the number of CFU/ml of the total microflora of the dental plaque. The number of CFU is reduced from 14.3 ± 0.12 . 103/ml up to 2.4 ± 0.3 . 102/ml after exposure (Table 1). Comparing the data of the control (the initial number of the colonies grown) and the experiment (the number of the colonies grown after the photoactivated disinfection) we have found that the antibacterial action of photoactivated disinfection depends directly on duration of exposure. Thus, the effectiveness of combined use of a photosensitizer with LILR is 1.2 times higher than that of ethacridine lactate (the exposure time is 60 seconds), and 2.0 times higher than the antimicrobial effect of the laser blue spectrum (the exposure time is 120 seconds).В проведенном исследовании изучали влияние НИЛИ на фоне фотосенсибилизатора (этакридина лактата) на селективную элиминацию патогенных и условно-патогенных микроорганизмов. Учитывая то, что этакридина лактату присущи свойства антисептика, следовало установить максимально возможное время воздействия этакридина лактата как фотосенсибилизатора. Установлено, что после воздействия риванола (этакридина лактата) в течение 1,5-3-х минут отмечалось бактерицидное действие на микроорганизмы. Воздействие антисептика в промежутке от 30 до 60 с не сопровождалось выраженным количественным изменением микробной популяции. Вторым этапом исследования стало определение чувствительности микроорганизмов к различным концентрациям фотосенсибилизатора. Использовали водный раствор этакридина лактата с концентрациями 0,1; 0,05; 0,01%. Полученные результаты позволяют сделать вывод, что раствор этакридина лактата в концентрации 0,1% повышает чувствительность микроорганизмов к действию низкоинтенсивного лазерного излучения. В ходе проведенного эксперимента было установлено антимикробное действие комбинированного влияния 0,1%-ого раствора этакридина лактата и лазерного излучения синего спектра, что проявляется снижением числа КОЕ/мл совокупной микрофлоры зубного налёта. Количество КОЕ снижается со значения 14,3±0,12 × 103/мл до значения 2,4±0,3 × 102/мл после облучения. Сопоставляя данные контроля (исходное число выросших колоний) и опыта (число колоний, выросших после проведения фотоактивированной дезинфекции), мы установили, что антимикробное действие фотоактивированной дезинфекции находится в прямой зависимости от длительности облучения. Так, эффективность комбинированного использования фотосенсибилизатора с НИЛИ в 1,2 раза превышает активность этакридина лактата (время экспозиции – 60 с) и в 2,0 раза превышает противомикробный эффект лазерного излучения синего спектра (время экспозиции – 120 с).У проведеному дослідженні вивчали вплив НІЛВ на тлі фотосенсибілізатора (етакридину лактату) на селективну елімінацію патогенних і умовно-патогенних мікроорганізмів. Враховуючи те, що етакридину лактату притаманні властивості антисептика, слід було встановити максимально можливий час дії етакридину лактату як фотосенсибілізатора. Встановлено, що після дії риванолу (етакридину лактату) протягом 1,5-3-х хвилин відзначалася бактерицидна дія на мікроорганізми. Дія ж антисептика в проміжку від 30 до 60 с не супроводжувалася вираженою кількісною зміною мікробної популяції. Другим етапом дослідження стало визначення чутливості мікроорганізмів до різних концентрацій фотосенсибілізатора. Використали водний розчин етакридину лактат у концентраціях 0,1; 0,05; 0,01%. Отримані результати дозволяють зробити висновок, що розчин етакридину лактату в концентрації 0,1% підвищує чутливість мікроорганізмів до дії низькоінтенсивного лазерного випромінювання. В ході проведеного експерименту було встановлено антимікробну дію комбінованого впливу 0,1%-вого розчину етакридину лактату і лазерного випромінювання синього спектра, що проявляється зниженням числа КУО/мл сукупної мікрофлори зубного нальоту. Кількість КУО знижується зі значення 14,3±0,12 × 103/мл до значення 2,4±0,3 × 102/мл після опромінення. Зіставляючи дані контролю (початкове число колоній, що виросли) і досліду (число колоній, що виросли після проведення фотоактивованої дезінфекції), ми встановили, що антимікробна дія фотоактивованої дезінфекції знаходиться в прямій залежності від тривалості опромінення. Так, ефективність комбінованого використання фотосенсибілізатора з НІЛВ в 1,2 рази перевищує активність етакридину лактату (час експозиції – 60 с) і в 2,0 рази перевищує антимікробний ефект лазерного випромінювання синього спектра (час експозиції – 120 с)

Analysis of fundamental parameters for V477 Lyr

We analyze the photometric and spectroscopic observations of the young pre-cataclysmic variable (pre-CV) V477 Lyr. The masses of both binary components have been corrected by analyzing their radial velocity curves. We show that agreement between the theoretical and observed light curves of the object is possible for several sets of its physical parameters corresponding to the chosen temperature of the primary component. The final parameters of V477 Lyr have been established by comparing observational data with evolutionary tracks for planetary nebula nuclei. The derived effective temperature of the O subdwarf is higher than that estimated by analyzing the object's ultraviolet spectra by more than 10000 K. This is in agreement with the analogous results obtained previously for the young pre-CVs V664 Cas and UU Sge. The secondary component of V477 Lyr has been proven to have a more than 25-fold luminosity excess compared to main-sequence stars of similar mass. Comparison of the physical parameters for the cool stars in young pre-CVs indicates that their luminosities do not correlate with the masses of the objects. The observed luminosity excesses in such stars show a close correlation with the post-common-envelope lifetime of the systems and should be investigated within the framework of the theory of their relaxation to the state of main-sequence stars. © 2008 Pleiades Publishing, Ltd

Spectral types of four binaries based on photometric observations

We present results of photometric and spectroscopic observations of four close binaries with subdwarf B components: PG 0918+029, PG 1000+408, PG 1116+301, PG 0001+275. We discovered that PG 1000+408 is a close binary, with the most probable orbital period being Porb = 1.041145 day. Based on a comparison of the observed light curves at selected orbital phases and theoretical predictions for their variations, all the systems are classified as doubly degenerate binaries with low-luminosity white-dwarf secondaries. © 2008 Pleiades Publishing, Ltd

PG 1316+678: A young pre-cataclysmic binary with weak reflection effects

The PG 1316+678 star is classified as a pre-cataclysmic binary, as is evidenced by its photometric and spectroscopic observations. Its orbital period is determined to be Porb = 3. 3803d, which coincides with the photometric period. The intensities of the emission HI and HeI lines are shown to vary synchronously with the brightness of the object (ΔmV = 0. 065m, ΔmR = 0. 08m). These variations arise as the UV radiation from the DAO white dwarf is reflected from the surface of the cold companion. The parameters of the binary are estimated and the time of its evolution after the common-envelope phase is determined to be t ≈ 240 000 years. Thus, PG 1316+678 is a young pre-cataclysmic NN Ser variable with the smallest known photometric reflection effect. © 2013 Pleiades Publishing, Ltd

Steps Toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XVI. A Thirteen-Year Study of Spectral Variability in NGC 5548

We present the final installment of an intensive 13-year study of variations of the optical continuum and broad H-beta emission line in the Seyfert 1 galaxy NGC 5548. The data base consists of 1530 optical continuum measurements and 1248 H-beta measurements. The H-beta variations follow the continuum variations closely, with a typical time delay of about 20 days. However, a year-by-year analysis shows that the magnitude of emission-line time delay is correlated with the mean continuum flux. We argue that the data are consistent with the simple model prediction that the size of the broad-line region is proportional to the square root of the ionizing luminosity. Moreover, the apparently linear nature of the correlation between the H-beta response time and the nonstellar optical continuum arises as a consequence of the changing shape of the continuum as it varies, specifically with the optical (5100 A) continuum luminosity proportional to the ultraviolet (1350 A) continuum luminosity to the 0.56 power.Comment: 20 pages plus 4 figures. Accepted for publication in The Astrophysical Journa