Bulgarian Academy of Sciences
Recent publications
Soil nematodes are one of the most important terrestrial faunal groups in Antarctica, as they are a major component of soil micro-food webs. Despite their crucial role in soil processes, knowledge of their species diversity and distribution is still incomplete. Taxonomic studies of Antarctic nematodes are fragmented, which prevents assessment of the degree of endemicity and distribution of the species, as well as other aspects of biogeography. The present study is focused on the nematode fauna of one of the three Antarctic sub-regions, the Maritime Antarctic and summarises all findings published up to April 2023. A species list that includes 44 species, belonging to 21 genera, 16 families and eight orders is provided. A review of the literature on terrestrial nematodes inhabiting the Maritime Antarctic showed that the sites are unevenly studied. Three islands (Signy, King George and Livingston Islands) revealed highest species richness, probably due to the highest rates of research effort. Most species and four genera ( Antarctenchus , Pararhyssocolpus , Amblydorylaimus and Enchodeloides ) are endemic, proving that nematode fauna of the Maritime Antarctic is autochthonous and unique. Several groups of islands/sites have been revealed, based on their nematode fauna. The study showed that species with a limited distribution prevailed, while only two species ( Plectus antarcticus and Coomansus gerlachei ) have been found in more than 50% of the sites. Based on the literature data, details on species localities, microhabitat distribution, plant associations and availability of DNA sequences are provided.
In this study, we analyzed the properties of amphiphilic alkyldi(methoxy poly(ethylene glycol) (MePEG)350-lactate) phosphates based on ethyl lactate, the monomethyl ether of poly(ethylene glycol)350, and alkyldichloro phosphates. Interestingly, these triesters combine two biodegradable bonds, –P(O)-O-C and –C(O)-O-C-, and include hydrophilic (MePEG350-lactate) and hydrophobic (R-aliphatic chain of alcohols) moieties. The properties of these esters resemble those of phospholipids. After being placed in an aqueous solution, they self-assembled. We also determined the effects of ester composition on micelle formation, stability, and size using dynamic light scattering. Solubilization tests using Sudan III or doxorubicin hydrochloride (Dox·HCl) revealed that they could be incorporated into the hydrophobic cores of dodecyl di(MePEG350-lactate) phosphate and hexadecyl di(MePEG350-lactate) phosphate. Notably, dodecyl di(MePEG350-lactate) phosphate was stable for five days, whereas hexadecyl di(MePEG350- lactate) phosphate was stable for seven days in phosphate-buffered saline. Moreover, Dox·HCl release rates from the micelles were approximately 30–40, 70–80, and 90–100% after 1, 5, and 28 d, respectively. graphical abstract Fullsize Image
Pollinators play a crucial role in ecosystems globally, ensuring the seed production of most flowering plants. They are threatened by global changes and knowledge of their distribution at the national and continental levels is needed to implement efficient conservation actions, but this knowledge is still fragmented and/or difficult to access. As a step forward, we provide an updated list of around 3000 European bee and hoverfly species, reflecting their current distributional status at the national level (in the form of present, absent, regionally extinct, possibly extinct or non-native). This work was attainable by incorporating both published and unpublished data, as well as knowledge from a large set of taxonomists and ecologists in both groups. After providing the first National species lists for bees and hoverflies for many countries, we examine the current distributional patterns of these species and designate the countries with highest levels of species richness. We also show that many species are recorded in a single European country, highlighting the importance of articulating European and national conservation strategies. Finally, we discuss how the data provided here can be combined with future trait and Red List data to implement research that will further advance pollinator conservation.
As in most European countries, as in our country, migrants have lower employment rates. However, there are differences between different groups of migrants. Refugees, as a separate and more specific migrant group, are much less integrated in the labour market. Their concentration tends to be in larger cities and regions, which creates numerous challenges for local authorities and labour markets. On the other hand, tracking the work, benefits and effects of refugee integration can support a more systematic approach to studying their labour integration based on actual activities. Given this, the purpose of this report is to emphasize the labour integration of refugees in a socio-economic perspective with a focus on the benefits of the process in the territory of Sofia. Research methods include synthesis and analysis of various sources, as well as review of the work of organizations, institutions and structures involved in the process. The results represent efforts and progress in relation to the labour integration of refugees, through cooperation and building sustainable partnerships. The conclusions show that in this way, not only policies, measures and good practices can be created to serve for the more successful integration of refugees, but also to achieve benefits and effects for the cities with their higher concentration of economic and social point of view.
The relationship between ICTs and the environment is complex and multifaceted, as ICTs can play positive and negative roles. The article's main idea is how the ICT sector can help tackle climate change, from measurement, monitoring, and automation of processes to self-organizing the sector to refurbish and ecologically scrape ICT hardware. The life cycle of services must be managed to minimize their impact on the environment – management of production, use, and end of life. Based on the analysis, the current article identified some groups of indicators used in the proposed model to estimate the ICT footprint. This information contributes to a more accurate measurement of any company the effect on the environment.
Background Aging affects anxiety levels in rats while the pineal gland, via its hormone melatonin, could modulate their inherited life “clock.” The present study aimed to explore the impact of plasma melatonin deficiency on anxiety responses and the possible involvement of the hypothalamic-pituitary-adrenocortical (HPA) axis and heat shock proteins (Hsp) 70 and 90 in the frontal cortex (FC) and the hippocampus in young adult, middle-aged and elderly rats with pinealectomy. Results Melatonin deficiency induced at different life stages did not affect the lifespan of rats. Pinealectomy abolished the circadian rhythm of motor activity, measured for 48 h in the actimeter, in young adult but not in middle-aged rats. Both 18-month-old sham- and rats with pinealectomy exhibited impaired circadian variations of motor activity. The same generations (3- and 18-month-old rats with pinealectomy) had lower anxiety levels than the matched sham groups, measured in three tests: elevated-plus maze, light-dark test, and novelty suppressing feeding test. While the activity of the HPA axis remained intact in young adult and middle-aged rats with melatonin deficiency, high baseline corticosterone level and blunted stress-induced mechanism of its release was detected in the oldest rats. Age-associated reduced Hsp 70 and 90 levels in the FC but not in the hippocampus were detected. Pinealectomy diminished the expression of Hsp 70 in the FC of middle-aged rats compared to the matched sham rats. Conclusions Our results suggest that while melatonin hormonal dysfunction impaired the circadian variations of motor activity and emotional behavior in young adult and elderly rats, the underlying pathogenic mechanism in these generations might be different and needs further verification.
The identity of Lithospermum rochelii , so far known only from its type locality (Bulgaria, hills in Plovdiv town), remained hitherto uncertain. Our examination of its original material and re‐collection of the species from its locus classicus in Plovdiv town revealed its identity with Lithospermum glandulosum (syn. Buglossoides glandulosa ) described later from an adjacent area, in the towns of Sadovo and Asenovgrad (Plovdiv Region), and Lithospermum czernjajevii (syn. Buglossoides czernjajevii ), described from north‐eastern Ukraine in the 20th century. The diagnostic characters of L. rochelii and related taxa are clarified, and the distribution area of this species is verified and mapped. A lectotype is designated for L. rochelii and a new combination is provided, Buglossoides rochelii . The chromosome number 2n = 2x = 16, the first ever record for the species, confirms its sharp separation from all other members of Buglossoides s.str., for which only the base chromosome number x = 7 has been known.
The applications of Raman spectroscopy have been limited by the presence of the fluorescence emitted by some samples. This interference can be depressed by shifting the excitation source used in Raman spectroscopy to the high‐energetic ultraviolet (UV) or deep ultraviolet (DUV) ranges. Plasmon resonance of aluminum (Al) nanostructures can play an important role in surface‐enhanced Raman spectroscopy (SERS) of fluorescence samples. Al active nanostructures have been produced for the first time on the aluminum nitride (AlN) substrates by nanosecond (ns) laser pulses or on fused silica by direct picosecond (ps) laser deposition. The efficiency of the Al active nanostructures produced on AlN for 355 nm SERS was simulated using the finite difference time domain (FDTD) method. The ability of using the Al active nanostructures has been proven for the first time to study rhodamine 6G (R6G) and methylene blue (MB) as probe fluorescing molecules for 355 nm SERS. The SERS spectra at different conditions have also been achieved.
Durotaxis motion is a spectacular phenomenon manifesting itself by the autonomous motion of a nano-object between parts of a substrate with different stiffness. This motion usually takes place along a stiffness gradient from softer to stiffer parts of the substrate. Here, we propose a new design of a polymer brush substrate that demonstrates antidurotaxis droplet motion, that is, droplet motion from stiffer to softer parts of the substrate. By carrying out extensive molecular dynamics simulation of a coarse-grained model, we find that antidurotaxis is solely controlled by the gradient in the grafting density of the brush and is favorable for fluids with a strong attraction to the substrate (low surface energy). The driving force of the antidurotaxial motion is the minimization of the droplet-substrate interfacial energy, which is attributed to the penetration of the droplet into the brush. Thus, we anticipate that the proposed substrate design offers a new understanding and possibilities in the area of autonomous motion of droplets for applications in microfluidics, energy conservation, and biology.
The Tirilman spaces , , were introduced by Casazza and Shura as variations of the spaces constructed by Tzafriri. We prove that all subsymmetric basic sequences in the dual space are equivalent to its canonical subsymmetic but not symmetric basis.
Dirac materials are characterized by the emergence of massless quasiparticles in their low-energy excitation spectrum that obey the Dirac Hamiltonian. Known examples of Dirac materials are topological insulators, d-wave superconductors, graphene, and Weyl and Dirac semimetals, representing a striking range of fundamental properties with potential disruptive applications. However, none of the Dirac materials identified so far shows metallic character. Here, we present evidence for the formation of free-standing molybdenene, a two-dimensional material composed of only Mo atoms. Using MoS2 as a precursor, we induced electric-field-assisted molybdenene growth under microwave irradiation. We observe the formation of millimetre-long whiskers following screw-dislocation growth, consisting of weakly bonded molybdenene sheets, which, upon exfoliation, show metallic character, with an electrical conductivity of ~940 S m⁻¹. Molybdenene when hybridized with two-dimensional h-BN or MoS2, fetch tunable optical and electronic properties. As a proof of principle, we also demonstrate applications of molybdenene as a surface-enhanced Raman spectroscopy platform for molecular sensing, as a substrate for electron imaging and as a scanning probe microscope cantilever.
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.
2,433 members
Denitsa Staicova
  • Institute for Nuclear Research and Nuclear Energy (INRNE)
Svilen Sabchevski
  • Emil Djakov Institute of Electronics
Ekaterina Peycheva
  • Roumen Tsanev Institute of Molecular Biology
1, 15th November str., 1040, Sofia, Bulgaria
Head of institution
Academician Julian Revalski
(+359 2) 979 53 33
(+359 2) 981 72 62