SORPTIVE PROPERTIES OF NATURAL MINERAL SORBENT TOWARDS HEPATITIS-B-SURFACE ANTIGEN

No abstrac

Silver Flowerlike Structures for Surface-Enhanced Raman Spectroscopy

Micro-and nanoflowers are a class of materials composed of particles with high surface-to-volume ratio. They have been extensively studied in the last decade due to simple preparation protocols and promising applications in biosensing, as drug delivery agents, for water purification, and so on. Flowerlike objects, due to their highly irregular surface, may act also as plasmonic materials, providing resonant coupling between optical waves and surface plasmon excitations. This fact allows us to infer the possibility to use micro-and nanoflowers as effective surface-enhanced Raman scattering (SERS) substrate materials. Here, we report on the design and Raman enhancement properties of silver flowerlike structures, deposited on aluminum surface. A simple and cost-effective fabrication method is described, which leads to SERS substrates of high developed surface area. The morphology of the silver flowers on a nanoscale is characterized by self-organized quasiperiodic stacks of nanosheets, which act as plasmonic cavity resonators. The substrates were tested against rhodamine-6G (R6G) water solutions of concentration varying between 10−3 M and 10−7 M. Optimal SERS enhancement factors of up to 105 were established at R6G concentrations in the 10−6–10−7 M range. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.This research was funded by the Bulgarian-Russian bilateral project through the contracts KP-06-15/27.09.2019 Russia with the Bulgarian National Fund of Scientific Research (G.G.T, N.D.T., S.C.R., and V.G.I.) and RFBR project No. 19-52-18008 Bulg (A.V.L.)

Species History Masks the Effects of Human-Induced Range Loss – Unexpected Genetic Diversity in the Endangered Giant Mayfly Palingenia longicauda

Freshwater biodiversity has declined dramatically in Europe in recent decades. Because of massive habitat pollution and morphological degradation of water bodies, many once widespread species persist in small fractions of their original range. These range contractions are generally believed to be accompanied by loss of intraspecific genetic diversity, due to the reduction of effective population sizes and the extinction of regional genetic lineages. We aimed to assess the loss of genetic diversity and its significance for future potential reintroduction of the long-tailed mayfly Palingenia longicauda (Olivier), which experienced approximately 98% range loss during the past century. Analysis of 936 bp of mitochondrial DNA of 245 extant specimens across the current range revealed a surprisingly large number of haplotypes (87), and a high level of haplotype diversity (). In contrast, historic specimens (6) from the lost range (Rhine catchment) were not differentiated from the extant Rába population (, ), despite considerable geographic distance separating the two rivers. These observations can be explained by an overlap of the current with the historic (Pleistocene) refugia of the species. Most likely, the massive recent range loss mainly affected the range which was occupied by rapid post-glacial dispersal. We conclude that massive range losses do not necessarily coincide with genetic impoverishment and that a species' history must be considered when estimating loss of genetic diversity. The assessment of spatial genetic structures and prior phylogeographic information seems essential to conserve once widespread species

Variable Stars in Galactic Globular Clusters

Based on a search of the literature up to May 2001, the number of known variable stars in Galactic globular clusters is approximately 3000. Of these, more than 2200 have known periods and the majority (approximately 1800) are of the RR Lyrae type. In addition to the RR Lyrae population, there are approximately 100 eclipsing binaries, 120 SX Phe variables, 60 Cepheids (including population II Cepheids, anomalous Cepheids and RV Tauri) and 120 SR/red variables. The mean period of the fundamental mode RR Lyrae variables is 0.585, for the overtone variables it is 0.342 (0.349 for the first-overtone pulsators and 0.296 for the second-overtone pulsators) and approximately 30% are overtone pulsators. These numbers indicate that about 65% of RR Lyrae variables in Galactic globular clusters belong to Oosterhoff type I systems. The mean period of the RR Lyrae variables in the Oosterhoff type I clusters seems to be correlated with metal abundance in the sense that the periods are longer in the more metal poor clusters. Such a correlation does not exist for the Oosterhoff type II clusters. Most of the Cepheids are in clusters with blue horizontal branches.Comment: 45 pages, 10 figures, to be published in AJ November 200

Integration of C-XSC Automatic Differentiation in Mathematica

[Popova Evgenija D.; Попова Евгения Д.]; [Кrämer Walter; Крамер Уолтър]; [Russev Milan; Русев Милан]Building interval software interoperability can be a good solution when re-using high-quality legacy code or when accessing functionalities unavailable natively in one of the software environments. C-XSC is a C++ class library supporting data objects and problem solving modules for computing with uncertain (interval) data and providing validated numerical results. This work focuses on the integration of C-XSC modules that require nonlinear functions as input data, in particular the modules for automatic differentiation, in Mathematica via MathLink communication protocol. A key result of this work is a mechanism (and software) which communicates and provides compatibility between the representation of nonlinear functions specified as Mathematica expressions and objects of suitable classes supported by the C-XSC automatic differentiation modules. The application of this basic communication software is demonstrated by developing three MathLink compatible programs which embed in Mathematica the three C-XSC modules for automatic differentiation as packages. The design methodology, some implementation issues and the use of both the basic software communicating functional expressions and the interfacing MathLink software embedding automatic differentiation modules in Mathematica are discussed. ACM: D.2.I2, D.2.13, G.4

Note : simple vacuum feedthrough for optical fiber with SubMiniature version A connectors at both ends

We present a simple way to insert an optical fiber, with existing standard SubMiniature version A connectors on both ends into a vacuum system. The fitting is tested in scanning electron microscope, at working pressures down to 2 × 10⁻⁵ mbar for cathodoluminescent measurements. With slight modifications this fitting could be successfully adapted for optical fiber insertion into pressurized systems.2 page(s

Bovine leukaemia as an experimental model of viral T-cell leukaemia in humans.

peer reviewe