Biosensors Using Free and Immobilized Cells of Luminous Bacteria

The technologies of receiving free and immobilized photobacteria cells for biomonitoring of toxins are considered. The mechanisms of interaction of toxins with photobacteria are observed. The main attention is paid to the immobilized procedures and structures of carriers. Data on poly(vinyl)alcohol (PVA) cryogel immobilization of different strains of photobacteria are presented. It is established that intensity and stability of light emission of PVA cells is competently controlled by: (1) intensity and persistence of a luminescent cycle using bacterial strain; (2) type of the carrier and the composition of the gel-formation medium; (3) freeze-thawing procedures; and (4) physical and chemical conditions of storage and application. The developed technology of cryogenic gel formation has kept the survival of luminous bacteria in the carrier practically at 100% without the introduction of additional cryoprotecting agents and procedures of a light induction. With storage at −80°C, bioluminescent activity remained without changes about 2 years. Using the immobilized preparations of biosensor, the discrete and continuous analysis of heavy metals, chlorophenols, and pesticides is carried out. The sensitivity of free and immobilized cells to the chosen toxicants is approximately identical. The continuous monitoring of toxicant conditions is optimized

Inverse time-dependent source problem for the heat equation with nonlocal boundary conditions

In this paper, we consider inverse problems of finding the time-dependent source function for the population model with population density nonlocal boundary conditions and an integral over-determination measurement. These problems arise in mathematical biology and have never been investigated in the literature in the forms proposed, although related studies do exist. The unique solvability of the inverse problems are rigorously proved using generalized Fourier series and the theory of Volterra integral equations. Continuous dependence on smooth input data also holds but, as in reality noisy errors are random and non-smooth, the inverse problems are still practically ill-posed. The degree of ill-posedness is characterised by the numerical differentiation of a noisy function. In the numerical process, the boundary element method together with either a smoothing spline regularization or the first-order Tikhonov regularization are employed with various choices of regularization parameter. One is based on the discrepancy principle and another one is the generalized cross-validation criterion. Numerical results for some benchmark test examples are presented and discussed in order to illustrate the accuracy and stability of the numerical inversion

RESEARCH OF PROCESSES OF HEAT TRANSFER IN THE COOLING SYSTEM ELEMENTS REA, MADE ON THE BASIS OF MELTING HEAT ACCUMULATORS WITH ADDITIONAL LIQUID HEAT SINK

The paper considers the system of cooling elements REA with intermittent by heat, made on the basis of melting heat accumulators with additional liquid heat sink. The basic computational relations for theoretical studies. Presents the dependence of the length of stable work of the REA element in ensuring its temperature conditions of the investigated system

Investigation of conduction band structure, electron scattering mechanisms and phase transitions in indium selenide by means of transport measurements under pressure

In this work we report on Hall effect, resistivity and thermopower measurements in n-type indium selenide at room temperature under either hydrostatic and quasi-hydrostatic pressure. Up to 40 kbar (= 4 GPa), the decrease of carrier concentration as the pressure increases is explained through the existence of a subsidiary minimum in the conduction band. This minimum shifts towards lower energies under pressure, with a pressure coefficient of about -105 meV/GPa, and its related impurity level traps electrons as it reaches the band gap and approaches the Fermi level. The pressure value at which the electron trapping starts is shown to depend on the electron concentration at ambient pressure and the dimensionality of the electron gas. At low pressures the electron mobility increases under pressure for both 3D and 2D electrons, the increase rate being higher for 2D electrons, which is shown to be coherent with previous scattering mechanisms models. The phase transition from the semiconductor layered phase to the metallic sodium cloride phase is observed as a drop in resistivity around 105 kbar, but above 40 kbar a sharp nonreversible increase of the carrier concentration is observed, which is attributed to the formation of donor defects as precursors of the phase transition.Comment: 18 pages, Latex, 10 postscript figure

PHASES High Precision Differential Astrometry of delta Equulei

delta Equulei is among the most well-studied nearby binary star systems. Results of its observation have been applied to a wide range of fundamental studies of binary systems and stellar astrophysics. It is widely used to calibrate and constrain theoretical models of the physics of stars. We report 27 high precision differential astrometry measurements of delta Equulei from the Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES). The median size of the minor axes of the uncertainty ellipses for these measurements is 26 micro-arcseconds. These data are combined with previously published radial velocity data and other previously published differential astrometry measurements using other techniques to produce a combined model for the system orbit. The distance to the system is determined to within a twentieth of a parsec and the component masses are determined at the level of a percent. The constraints on masses and distance are limited by the precisions of the radial velocity data; we outline plans improve this deficiency and discuss the outlook for further study of this binary.Comment: Accepted by AJ. Complete versions of tables 2-7 now available at http://stuff.mit.edu/~matthew1/deltaEquTables/ (removed from astroph server

Гидрофобизация и упрочнение целлюлозных материалов из вторичных ресурсов

The influence of the sizing agent and filler on the physical-mechanical and surface properties of paper from the cellulose mass of the inner layer of the bark of mulberry tree branches has been studied. According to standard methods, the mechanical strength and absorbency were studied. Surface absorbency for one-side wetting was determined by the method of Cobb(30), by determining the mass of water absorbed by the paper surface when wetting one side of the test sample. It was found that it is advisable to add a sizing agent in the range from 1 to 1.5 g per 100 g of dry cellulose raw materials, since an increase in the additive to 2 g helps to reduce the interfiber bonding forces by 21 %. The addition of 6 g of kaolin affects the distance between the fibers, which reduces the mechanical adhesive forces by 12.5 %. During the analysis of the surface properties of paper samples, the sizing efficiency was found to be from 22.5 to 30 % with an increase in the addition of sizing glue, which can be explained by densification of the structure, which prevents the penetration of aqueous solutions. The addition of 2 to 6 g of kaolin also increases water resistance from 17.5 to 25 %. With the help of a mathematical model, rational values of absorbency were revealed with a composition of 92 %, with a sizing agent of 1.5 g and an amount of filler of 4 g. The resulting mathematical model can be used as the basis for controlling the surface characteristics of paper during its production.Исследовано влияние проклеивающего вещества и наполнителя на физико-механические и поверхностные свойства бумаги из целлюлозной массы внутреннего слоя коры веток тутового дерева. По стандартным методикам изучены механическая прочность и впитывающая способность. Поверхностную впитываемость при одностороннем смачивании определяли по методу Кобб(30), путем определения массы воды, поглощенной поверхностью бумаги при смачивании одной стороны испытуемого образца. Выявлено, что целесообразно добавление проклеивающего вещества в пределах от 1 до 1,5 г на 100 г сухого целлюлозного сырья, так как увеличение добавки до 2 г способствует уменьшению межволоконных сил связи на 21 %. Добавление каолина в количестве 6 г влияет на расстояние между волокнами, что уменьшает механические силы сцепления на 12,5 %. В ходе анализа поверхностных свойств образцов бумаги определена эффективность проклейки от 22,5 до 30 % с увеличением проклеивающего вещества, что можно объяснить уплотнением структуры, которая препятствует проникновению водных растворов. Добавление каолина от 2 до 6 г также повышает стойкость к воде от 17,5 до 25 %. С помощью математической модели показаны рациональные значения впитывающей способности при составе бумажной массы 92 % при проклеивающем веществе 1,5 г и количестве наполнителя 4 г. Полученная математическая модель может быть положена в основу управления поверхностных характеристик бумаги в процессе ее производства

Поверхностные и оптические свойства бумаги, содержащей карбонат кальция

The article investigates the surface and optical properties of calcium carbonate paper obtained at the UzbekChinese enterprise Fergana stone paper company (Uzbekistan), in order to identify the possibility of their use at printing enterprises for printing multicolor products using traditional printing methods. According to the results of a quantitative assessment of the surface quality by the indirect Beck method, we can say that paper sample 1 has a smoothness like coated paper (750–1500 s), paper samples 2 and 3 – like calendered paper, so that these paper samples can be recommended for prints with increased quality requirements. Smaller values of roughness Ra and small depressions, expressed by darkening in the topographic AFM images, characterized sufficient homogeneity and density of the structure. It was also revealed that the surface of the paper samples has a high ability to specularly reflect the incident light, since the percentage of surface reflection is similar to that of coated papers. Samples of paper have a whiteness of about 90 % and do not have a tint, since the difference between the maximum and minimum values of the reflection coefficients on a white stack is not more than 10 %. The tested paper samples can be recommended without restrictions for double-sided printing, since the opacity index is more than 92 %.Исследованы поверхностные и оптические свойства бумаги из карбоната кальция, полученной в условиях Узбекско-китайского предприятия Fergana stone paper company (Узбекистан), с целью выявления возможности ее использования на полиграфических предприятиях для печати многокрасочной продукции с применением традиционных способов печати. По результатам количественной оценки качества поверхности косвенным методом Бека можно утверждать, что образец бумаги № 1 обладает гладкостью, как у мелованной бумаги (750–1500 с), образцы бумаги № 2 и 3, как у бумаг каландрированных, которые можно рекомендовать для изданий с повышенными требованиями к качеству. Меньшие значения шероховатости Ra и небольшие углубления, выраженные затемнением на топографических АСМ-изображениях, характеризовали достаточную однородность и плотность структуры. Также выявлено, что поверхность образцов бумаги обладает высокой способностью зеркально отражать падающий свет, так как процент отражения поверхностей такой же, как у мелованных бумаг. Образцы бумаги имеют белизну порядка 90 % и нет оттенка, так как разница между максимальным и минимальным значениями коэффициентов отражения на белой стопе не больше 10 %. Исследуемые образцы бумаги можно без ограничений рекомендовать для двусторонней печати, так как показатель светонепроницаемости больше 92 %

Multi-stage urethroplasy for anterior urethral strictures: objective parameters of long-term efficacy and patient-reported outcomes

Introduction. Multi-stage urethral surgery is used in cases of the most complex urethral strictures. The evaluation of surgical treatment results given by patients is a significant criterion for the efficacy of urethroplasty along with the assessment of urethral patency through instrumental examinations.Objective. To evaluate the long-term efficacy of multistage urethroplasty for complex anterior urethral strictures considering the patients' quality of life and satisfaction with the surgical outcomes.Materials and methods. The study included 73 patients aged 18 – 84 years with anterior urethral strictures who underwent multi-stage urethroplasty in 2010 – 2019. Surgical and functional outcomes of urethroplasty were assessed through general blood and urine tests, physical examination, uroflowmetry, and retrograde urethrography and urethroscopy in case of urinary disorders.  Subjective parameters of treatment efficacy were studied using questionnaires: International Prostate Symptom Score (IPSS); Quality of life (QoL); Patient-reported Outcome Measure for Urethral Stricture Surgery (USS-PROM); Patient Global Impression of Improvement (PGI-I).Results. Recurrent urethral stricture was detected in 19 (26,0%) patients with the average follow-up period being 65 months. Independent urination was restored in 71 (97.3%) cases, including repeated interventions. After surgery, there was a significant increase in urinary flow rate parameters (Q max: 8.1 vs 19.1 ml/s, p < 0.0001; Q ave: 5.5 vs 10.7 ml/s; p = 0.0004), decrease in residual urine volume (62.4 vs 18.6 ml, p < 0.0001), decrease in total IPSS score (18.7 vs 5.7 points; p < 0.0001) and QoL index (4.3 vs 1 .8 points, p < 0.0001). A comparative analysis of preoperative and postoperative USS-PROM questionnaire results demonstrated an improvement in indicators assessing LUTS (12.9 vs 3.4 points; p < 0.0001; 3.6 vs 1.7 points; p < 0.0001), and urination-associated quality of life (2.6 vs 0.6 points; p < 0.0001) and overall health (EQ-5D index: 0.73 vs 0.91 points; p = 0.025; EQ-VAS: 68.0 vs 88.1 points, p = 0.004). Fifty-seven (81.4%) men were “very satisfied” or “satisfied” with the treatment outcomes, while nine (12.9%) respondents noted a moderate effect of residual urinary disorders on the quality of life. Significantly higher satisfaction was observed among cystostomy patients and in cases where repeated interventions were unnecessary.Conclusion. Multi-stage urethroplasty for complex anterior urethral strictures achieves efficacy in 97.3% of cases and is accompanied by high levels of quality of life and patient’s satisfaction during long-term follow-up

The Disk Wind in the Young Binaries and the Origin of the Cyclic Activity of Young Stars

We present results of numerical modeling of the cyclic brightness modulation in the young binary systems with the eccentric orbits and low-mass secondary components. Brightness variations of the primary is due to the periodical extinction variations on the line-of-sight caused by the disk wind of the secondary and a common envelope it produces. A matter distribution in the envelope has been calculated in the ballistic approach. Calculations showed that for the young binaries with the elliptic orbits parameters of the photometric minima (their depth, duration and the shape of light curves) depend not only on the disk wind parameters and an inclination of the binary orbit to the line-of-sight but also on the longitude of the periastron. A modulation of the scattered radiation of the common envelope with a phase of the orbital period has been investigated in the single scattering approach. It is shown that an amplitude of the modulation is maximal when the system is seen edge-on and has also a non-zero value in the binaries observed pole-on. Possible applications of the theory to the young stellar objects are discussed. In particular, an attention is payed to a resemblance of the light curves in some models with light curves of the objects suspected as candidates to FUORs.Comment: 18 pages, 9 figures, accepted by Astronomy Letter

The GRANDMA network in preparation for the fourth gravitational-wave observing run

GRANDMA is a world-wide collaboration with the primary scientific goal ofstudying gravitational-wave sources, discovering their electromagneticcounterparts and characterizing their emission. GRANDMA involves astronomers,astrophysicists, gravitational-wave physicists, and theorists. GRANDMA is now atruly global network of telescopes, with (so far) 30 telescopes in bothhemispheres. It incorporates a citizen science programme (Kilonova-Catcher)which constitutes an opportunity to spread the interest in time-domainastronomy. The telescope network is an heterogeneous set of already-existingobserving facilities that operate coordinated as a single observatory. Withinthe network there are wide-field imagers that can observe large areas of thesky to search for optical counterparts, narrow-field instruments that dotargeted searches within a predefined list of host-galaxy candidates, andlarger telescopes that are devoted to characterization and follow-up of theidentified counterparts. Here we present an overview of GRANDMA after the thirdobserving run of the LIGO/VIRGO gravitational-wave observatories in $2019-2020$and its ongoing preparation for the forthcoming fourth observational campaign(O4). Additionally, we review the potential of GRANDMA for the discovery andfollow-up of other types of astronomical transients.<br