Surface abundances of light elements for a large sample of early B-type stars - IV. The magnesium abundance in 52 stars - a test of metallicity

From high-resolution spectra a non-LTE analysis of the MgII 4481.2 A feature is implemented for 52 early and medium local B stars on the main sequence (MS). The influence of the neighbouring line AlIII 4479.9 A is considered. The magnesium abundance is determined; it is found that log e(Mg) = 7.67 +- 0.21 on average. It is shown that uncertainties in the microturbulent parameter Vt are the main source of errors in log e(Mg). When using 36 stars with the most reliable Vt values derived from OII and NII lines, we obtain the mean abundance log e(Mg) = 7.59 +- 0.15. The latter value is precisely confirmed for several hot B stars from an analysis of the MgII 7877 A weak line. The derived abundance log e(Mg) = 7.59 +- 0.15 is in excellent agreement with the solar magnesium abundance log e_sun(Mg) = 7.55 +- 0.02, as well as with the proto-Sun abundance log e_ps(Mg) = 7.62 +- 0.02. Thus, it is confirmed that the Sun and the B-type MS stars in our neighbourhood have the same metallicity.Comment: 9 pages, 6 figures. Has been accepted for publication at MNRA

Composition based on aluminum oxide and polydimethylsiloxane matrix for enhancing drug targeting

Methodological approaches developed at Research Institute of Clinical and Experimental Lymphology for a number of years allow formulating the importance of embedding active pharmaceutical ingredients (API) in the structure of porous carriers (sorbents). The composition of the carrier and API is an enteral system for prolonged dosing of pharmacological agents, which allows providing a specific pharmacological effect and safety of use. The pores of the media (sorbents) act as containers for API. This is especially important for rapidly absorbed drugs, which include, for example, lithium preparations that are used in narrow concentration limits due to their side effects. At the moment, an innovative technology for creating new medicines with an improved combination of efficiency and safety (pharmacological upgrade) has been developed and implemented. The essence of the technology is to create a composition of aluminum oxide and polydimethylsiloxane (matrix) and an active pharmacological ingredient (API). A study of two drugs based on matrix / lithium citrate and matrix / melatonin showed continued specific pharmacological activity of API, better pharmacokinetics, and better safety parameters. The matrix of aluminum oxide and polydimethylsiloxane provides an upgrade of the pharmacological properties of drugs for the dosed and safe delivery of API to the zone of their therapeutic effect

MECHANISMS OF ACTION OF LITHIUM COMPOUNDS

This review summarizes the literature data on the role of lithium compounds in modern pharmacotherapy of various diseases of the central nervous system. Attention is also paid to other therapeutic properties of lithium in atherosclerosis, cardiovascular diseases, diabetes, hematopoietic disorders, inflammation, and diseases of the urinary system. Possible ways of delivering lithium into the body have been charted, in particular, when lithium salt is combined with a sorbent (solid porous carrier). Such compounds have additional therapeutic properties. Data on the significance of lithium compounds in studies on models of diseases of the nervous system in animals are analyzed. Among these models, models of neonatal ischemia/hypoxia of the brain in vivo, neurodegenerative diseases, psychopathological states (aggressiveness, depression) and craniocerebral injury are discussed. There are researches in which the results of the lithium preparations use in clinical practice are investigated. It emphasizes the influence of genetic factors on the lithium effects. Particular attention is paid to the possibility of preventing the toxicity of lithium compounds for the body. The currently known molecular mechanisms of lithium action are discussed: inhibition of glycogen synthase kinase 3β (GSK-3β) and inositol monophosphatase 1 (IMPA1), which have key value for autophagy, oxidative stress, inflammation, mitochondrial function, induction of neurotrophic factors, apoptosis. It was concluded that the study of the molecular pathways of the functioning of lithium compounds empowers understanding both the reasons for its effectiveness in the nervous system diseases and the mechanisms of action on other body systems

Silver containing sorbents: Physicochemical and biological properties

New silver containing sorbents, based on mineral carriers, such as alumina and silica systems with a meso- and macro- porous structure, have a higher mechanical resistance and, hydrophilic and hydrophobic chemical composition of the surface. These sorbents are easy to find and relatively inexpensive, compared to their known equivalents. They are furthermore characterised by high specific surface and simple preparation, whilst the addition of silver considerably increases their antiseptic activity. The results of research of the physical, chemical and biological properties of the developed substances, as well as bio-comparability of sorbents with biological tissues, are presented in this paper. The modified material acts simultaneously as the carrier for active substances to the area of therapeutic application and as a sorbent used to remove toxic agents from such areas. This approach led us to modify the sorbent, and prolong the delivery of substances such as silver, as an effective antibacterial and antimycotic agent

Accurate Fundamental Parameters or A, F, and G-type Supergiants in the Solar Neighbourhood

The following parameters are determined for 63 Galactic supergiants in the solar neighbourhood: effective temperature Teff, surface gravity log g, iron abundance log e(Fe), microturbulent parameter Vt, mass M/Msun, age t and distance d. A significant improvement in the accuracy of the determination of log g and, all parameters dependent on it, is obtained through application of van Leeuwens (2007) re-reduction of the Hipparcos parallaxes. The typical error in the log g values is now +-0.06 dex for supergiants with distances d < 300 pc and +-0.12 dex for supergiants with d between 300 and 700 pc; the mean error in Teff for these stars is +-120 K. For supergiants with d > 700 pc parallaxes are uncertain or unmeasurable, so typical errors in their log g values are 0.2-0.3 dex. A new Teff scale for A5-G5 stars of luminosity classes Ib-II is presented. Spectral subtypes and luminosity classes of several stars are corrected. Combining the Teff and log g with evolutionary tracks, stellar masses and ages are determined; a majority of the sample has masses between 4 Msun and 15 Msun and, hence, their progenitors were early to middle B-type main sequence stars. Using Fe ii lines, which are insensitive to departures from LTE, the microturbulent parameter Vt and the iron abundance log e(Fe) are determined from high-resolution spectra. The parameter Vt is correlated with gravity: Vt increases with decreasing log g. The mean iron abundance for the 48 supergiants with distances d < 700 pc is log e(Fe)=7.48+-0.09, a value close to the solar value of 7.45+-0.05, and thus the local supergiants and the Sun have the same metallicity.Comment: 12 pages, 9 figures. Will be published at MNRA

Nitrogen Enrichment in Atmospheres of A- and F- Type Supergiants

Using new accurate fundamental parameters of 30 Galactic A and F supergiants, namely their effective temperatures Teff and surface gravities log g, we implemented a non-LTE analysis of the nitrogen abundance in their atmospheres. It is shown that the non-LTE corrections to the N abundances increase with Teff. The nitrogen overabundance as a general feature of this type of stars is confirmed. A majority of the stars has a nitrogen excess [N/Fe] between 0.2 and 0.9 dex with the maximum position of the star's distribution on [N/Fe] between 0.4 and 0.7 dex. The N excesses are discussed in light of predictions for B-type main sequence (MS) stars with rotationally induced mixing and for their next evolutionary phase, i.e. A- and F-type supergiants that have experienced the first dredge-up. Rotationally induced mixing in the MS progenitors of the supergiants may be a significant cause of the nitrogen excesses. When comparing our results with predictions of the theory developed for stars with the mixing, we find that the bulk of the supergiants (28 of 30) show the N enrichment that can be expected (i) either after the MS phase for stars with the initial rotational velocities v0 = 200-400 km s-1, (ii) or after the first dredge-up for stars with v0 = 50-400 km s-1. The latter possibility is preferred on account of the longer lifetime for stars on red-blue loops following the first dredge-up. Two supergiants without a discernible N enrichment, namely HR 825 and HR 7876, may be post-MS objects with the relatively low initial rotational velocity of about 100 km s-1. The suggested range for v0 is approximately consistent with inferences from the observed projected rotational velocities of B-type MS stars, progenitors of A and F supergiants.Comment: 14 pages, 13 figure

Effects of habitat and land use on breeding season density of male Asian Houbara Chlamydotis macqueenii

Landscape-scale habitat and land-use influences on Asian Houbara Chlamydotis macqueenii (IUCN Vulnerable) remain unstudied, while estimating numbers of this cryptic, low-density, over-hunted species is challenging. In spring 2013, male houbara were recorded at 231 point counts, conducted twice, across a gradient of sheep density and shrub assemblages within 14,300 km² of the Kyzylkum Desert, Uzbekistan. Four sets of models related male abundance to: (1) vegetation structure (shrub height and substrate); (2) shrub assemblage; (3) shrub species composition (multidimensional scaling); (4) remote-sensed derived land-cover (GLOBCOVER, 4 variables). Each set also incorporated measures of landscape rugosity and sheep density. For each set, multi-model inference was applied to generalised linear mixed models of visit-specific counts that included important detectability covariates and point ID as a random effect. Vegetation structure received strongest support, followed by shrub species composition and shrub assemblage, with weakest support for the GLOBCOVER model set. Male houbara numbers were greater with lower mean shrub height, more gravel and flatter surfaces, but were unaffected by sheep density. Male density (mean 0.14 km-2, 95% CI, 0.12‒0.15) estimated by distance analysis differed substantially among shrub assemblages, being highest in vegetation dominated by Salsola rigida (0.22 [CI, 0.20‒0.25]), high in areas of S. arbuscula and Astragalus (0.14 [CI, 0.13‒0.16] and 0.15 [CI, 0.14‒0.17] respectively), lower (0.09 [CI, 0.08‒0.10]) in Artemisia and lowest (0.04 [CI, 0.04‒0.05]) in Calligonum. The study area was estimated to hold 1,824 males (CI: 1,645‒2,030). The spatial distribution of relative male houbara abundance, predicted from vegetation structure models, had the strongest correspondence with observed numbers in both model-calibration and the subsequent year’s data. We found no effect of pastoralism on male distribution but potential effects on nesting females are unknown. Density differences among shrub communities suggest extrapolation to estimate country- or range-wide population size must take account of vegetation composition

Studying the pharmacokinetic parameters of new normothymic drug based on the complex of lithium citrate, aluminum oxide and polymethylsiloxane

For the treatment of bipolar affective disorders, lithium preparations are the most famous and effective. But the main problem with the use of lithium preparations is the narrow «therapeutic corridor». An urgent task is the creation of dosage forms of lithium with a slow release and a wide therapeutic range. The study object was a new normotymic drug based on lithium, aluminum oxide and polymethylsiloxane. Due to the new carrier matrix lithium is released from its porous structure gradually providing a prolonged effect and maintaining an optimal concentration in the blood which also helps to minimize side effects. The purpose of the study was to explore the pharmacokinetic parameters of a normotymic drug based on a complex lithium citrate, aluminum oxide and polymethylsiloxane (LOAP).Material and methods: for the assessment of pharmacokinetic parameters the method of atomic emission spectrometry with inductively coupled plasma and two-chamber modeling were used.Results and discussion. The pharmacokinetic data showed a linear nature of pharmacokinetics of the drug based on LOAP as the foundation of data of the lithium’s amount in the blood plasma of rabbits after intragastric administration at doses of 200, 400 and 800 mg/kg. The drug with intragastric administration at a dose of 800 mg/kg is well absorbed from the gastrointestinal tract, with bioavailability (F) 74 %. This dose shows the maximum increase of the area under the pharmacokinetic curve (AUC - 32787.1 (ng x h)/ ml), and indicators of elimination constant (Kel - 0.062 h-1), clearance (Cl - 0.09 l/(kg x h)), elimination half-life (T1/2p - 11.436 h) in comparison with other doses remain unchanged

The effect of silver-containing sorbent on red blood cells during hemosorption: an <i>in vitro</i> study

The aim of the study was to investigate the influence of the original porous silver–containing sorbent on the morphofunctional parameters of red blood cells during in vitro hemoperfusion. Material and methods. Donor blood was perfused through glass columns filled with a sorbent based on porous aluminum oxide, polydimethylsiloxane and silver nanoclusters and a sorbent without silver. The effect of a silver-containing sorbent on the change in morphofunctional parameters of red blood cells after perfusion through sorbents was determined by scanning flow cytometry. Results and their discussion. Due to the uniformity of the distribution of silver (0.1 %) over the sorbent granules, the parameters of the porous structure – the specific surface area and pore volume – practically do not change compared to the sorbent without silver. Morphological parameters of original donor blood and after hemoperfusion are within the norm. The functional parameters are also normal, although the introduction of silver in to the sorbent slightly increases the number of active band 3 (B3) proteins on erythrocyte membranes, both in comparison with the donor red cell mass as a control and in comparison with the sorbent without silver. There is also an increase in the ultimate extensibility of the erythrocyte membrane compared to the original blood (2.2 times) and the sorbent without silver (1.4 times). Conclusions. A sorbent modified with silver and a sorbent without silver does not have a damaging toxic effect on the morphofunctional parameters of blood under perfusion conditions. The mechanisms affecting the indicators of the ultimate extensibility of the erythrocyte membrane after blood perfusion through a silver-containing sorbent require further research