538 results on '"Dimitar Dimitrov"'
Search Results
2. Soil erosion rates based on anatomical changes in exposed roots - case study from southwest Bulgaria
- Author
-
Eli Pavlova-Traykova and Dimitar Dimitrov
- Subjects
Soil erosion ,dendrogeomorphology ,Sedelska river ,Forestry ,SD1-669.5 ,Animal culture ,SF1-1100 ,Plant culture ,SB1-1110 - Abstract
In recent years different methods for soil erosion assessment have been used. Because of its high accuracy in estimations, dendrogeomorphology was selected as one suitable and reliable scientific method to achieve the main goals of this study. The main goal of the study is to date denudation events using anatomical responses of the tree-rings of the roots. We analyze the histological changes that occur in the roots of two tree species, along the river banks of the Sedelska River, which is a tributary of Struma River.The significant differences between homogenous groups of measurements in pre-exposed and exposed roots was established, and it shows a remarkable response of roots to sheet erosion.
- Published
- 2023
- Full Text
- View/download PDF
3. Effects of anthropogenic and environmental stressors on the current status of red mullet (Mullus barbatus L., 1758) populations inhabiting the Bulgarian Black Sea waters
- Author
-
Ivelina Zlateva, Violin Raykov, Albena Alexandrova, Petya Ivanova, Nesho Chipev, Kremena Stefanova, Nina Dzhembekova, Valentina Doncheva, Violeta Slabakova, Elitsa Stefanova, Svetlana Mihova, Nadezhda Valcheva, Ognyana Hristova, Boryana Dzhurova, Dimitar Dimitrov, Almira Georgieva, Elina Tsvetanova, Madlena Andreeva, Ivan Popov, Mariya Yankova, Yordan Raev, and Konstantin Petrov
- Subjects
Ecology ,QH540-549.5 ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
The red mullet (Mullus barbatus Linnaeus, 1758) is a keynote species for the Bulgarian Black Sea ecosystem and fisheries; nevertheless, existing knowledge on population status is very scarce. The present study was intended to assess the health status and adaptive potential of M. barbatus populations inhabiting the Bulgarian waters of the Black Sea. Our findings revealed that populations of M. barbatus are exposed to a variety of anthropogenic and environmental stressors. The species’ status was assessed using representative genetic, morphological, biochemical and chemical biomarkers from specimens obtained in the research area’s northern and southern regions. Based on mtDNA markers, genetic analysis revealed low haplotype and nucleotide diversity, typically observed in overexploited or “threatened” populations. Examining the morphology of the specimens revealed no discernible pattern of differentiation. Except for aluminium and chrome, metal and PAH concentrations in fish were below the regulatory thresholds. The specimens from the southern region ingested more microplastics than those from the northern region. The majority of specimens collected from the southern region also exhibited elevated levels of oxidative stress and decreased antioxidant defence, which can be interpreted as an early indication that they had reached the limits of their adaptive potential. Further research on the composite effects of the stressogenic environment on the Black Sea biota are critically needed, as well as the introduction of new indicators and thresholds at molecular and cellular levels for adequate monitoring of both the ecological state of the marine environment and its biota.
- Published
- 2023
- Full Text
- View/download PDF
4. Diversification of flowering plants in space and time
- Author
-
Dimitar Dimitrov, Xiaoting Xu, Xiangyan Su, Nawal Shrestha, Yunpeng Liu, Jonathan D. Kennedy, Lisha Lyu, David Nogués-Bravo, James Rosindell, Yong Yang, Jon Fjeldså, Jianquan Liu, Bernhard Schmid, Jingyun Fang, Carsten Rahbek, and Zhiheng Wang
- Subjects
Science - Abstract
Abstract The rapid diversification and high species richness of flowering plants is regarded as ‘Darwin’s second abominable mystery’. Today the global spatiotemporal pattern of plant diversification remains elusive. Using a newly generated genus-level phylogeny and global distribution data for 14,244 flowering plant genera, we describe the diversification dynamics of angiosperms through space and time. Our analyses show that diversification rates increased throughout the early Cretaceous and then slightly decreased or remained mostly stable until the end of the Cretaceous–Paleogene mass extinction event 66 million years ago. After that, diversification rates increased again towards the present. Younger genera with high diversification rates dominate temperate and dryland regions, whereas old genera with low diversification dominate the tropics. This leads to a negative correlation between spatial patterns of diversification and genus diversity. Our findings suggest that global changes since the Cenozoic shaped the patterns of flowering plant diversity and support an emerging consensus that diversification rates are higher outside the tropics.
- Published
- 2023
- Full Text
- View/download PDF
5. Pilot Survey of Outdoor Radon and Thoron Levels in Bulgaria Using an Innovative DVD-Based Method
- Author
-
Dobromir Pressyanov and Dimitar Dimitrov
- Subjects
radon outdoors ,thoron outdoors ,radon–thoron correlation ,novel method ,DVD-based method ,Meteorology. Climatology ,QC851-999 - Abstract
This study presents the results of a pilot survey utilizing an innovative DVD-based method to measure outdoor radon and thoron levels. Twenty-six discriminative radon/thoron detectors were deployed across four different territorial zones in Bulgaria. Positioned 1 m above the ground, these detectors were left in place for several months. Notably, the dataset reveals significant variability in measurements, even over short distances, with thoron exhibiting greater variability than radon. Radon levels ranged from 7 ± 1 to 34 ± 3 Bq m−3 (average: 21 Bq m−3), while thoron levels ranged from 13 ± 5 to 307 ± 54 Bq m−3 (average: 170 Bq m−3). A weak but statistically significant correlation (correlation coefficient: 0.559) was observed between radon and thoron levels, which improved significantly when averaged across the four zones. These findings underscore the importance of measuring both radon and thoron in outdoor surveys. High thoron levels can significantly bias radon measurements, particularly when radon concentrations are substantially lower than those of thoron. If further studies confirm the good correlation between area averages, the observed correlation between area-average values could be used to correct average radon levels in large areas (e.g., radon priority areas) for thoron interference when thoron data are missing from the analyzed radon dataset.
- Published
- 2024
- Full Text
- View/download PDF
6. Piscivorous Vertebrates That May Pose a Risk to the Critically Endangered Mandra Shemaya, Alburnus mandrensis (Drensky, 1943) (Actinopterygii; Leuciscidae)
- Author
-
Dimitar Dimitrov, Tihomir R. Stefanov, Vladimir Mladenov, Ivaylo Dimchev, Kiril Valkanov, Nikolay Kolev, and Nikolay Natchev
- Subjects
ecology ,habitat ,predator–prey interaction ,bio-risk ,invasion ,extinction ,Biology (General) ,QH301-705.5 - Abstract
In the present study, we provide a checklist of the predators that may impact the population of the critically endangered Mandra shemaya (Alburnus mandrensis Drensky, 1943). This endemic fish only inhabits the basin of Mandra Lake in the Burgas district (SE Bulgaria) and data on its biology are scarce. We have confirmed the presence of the Mandra shemaya in Mandra Lake for the last six years (including 2024) and provided an analysis on the potential predatory pressures on A. mandrensis. The recently recorded presence of a highly invasive piscivorous predatory fish in Mandra Lake is considered potentially dangerous for the sustainability of native fish species.
- Published
- 2024
- Full Text
- View/download PDF
7. First Records of Feather Mites and Haemosporidian Parasites in the Isabelline Wheatear (Oenanthe isabellina) from the Westernmost Part of the Species Breeding Range
- Author
-
Nevena Kolarova, Aneliya Bobeva, Mihaela Ilieva, Christoffer Sjöholm, and Dimitar Dimitrov
- Subjects
Analgoidea ,avian malaria ,passerine ,Plasmodium ,new host records ,Bulgaria ,Biology (General) ,QH301-705.5 - Abstract
Host range expansions are an important factor for shaping the community of associated symbiotic organisms. Birds, as a highly mobile group of animals, are of particular interest to study with respect to the diversity and the distribution of the organisms using them as hosts during such large-scale movements. The Isabelline wheatear (Oenanthe isabellina) is a species with a main breeding area in Asia, which has expanded west, towards the Balkans, since the middle of the last century. We collected feather mites and blood samples for haemosporidian parasites screening from adult and juvenile Isabelline wheatears from the westernmost edge of the species breeding area in western Bulgaria. The feather mite species Alaudicola rosickyi (Černy, 1963), previously found on other wheatear species, was found for the first time on Isabelline wheatears. One species of avian malaria parasites—Plasmodium relictum (Grassi and Feletti, 1891) (lineage SGS1)—represented the first record of a malaria parasite in this host species in Europe. Increasing the sampling in the South European populations of the species will shed light on blood parasite species diversity and will reveal if other feather mite species have followed their host during its breeding range expansion.
- Published
- 2024
- Full Text
- View/download PDF
8. An updated floristic map of the world
- Author
-
Yunpeng Liu, Xiaoting Xu, Dimitar Dimitrov, Loic Pellissier, Michael K. Borregaard, Nawal Shrestha, Xiangyan Su, Ao Luo, Niklaus E. Zimmermann, Carsten Rahbek, and Zhiheng Wang
- Subjects
Science - Abstract
Abstract Floristic regions reflect the geographic organization of floras and provide essential tools for biological studies. Previous global floristic regions are generally based on floristic endemism, lacking a phylogenetic consideration that captures floristic evolution. Moreover, the contribution of tectonic dynamics and historical and current climate to the division of floristic regions remains unknown. Here, by integrating global distributions and a phylogeny of 12,664 angiosperm genera, we update global floristic regions and explore their temporal changes. Eight floristic realms and 16 nested sub-realms are identified. The previously-defined Holarctic, Neotropical and Australian realms are recognized, but Paleotropical, Antarctic and Cape realms are not. Most realms have formed since Paleogene. Geographic isolation induced by plate tectonics dominates the formation of floristic realms, while current/historical climate has little contribution. Our study demonstrates the necessity of integrating distributions and phylogenies in regionalizing floristic realms and the interplay of macroevolutionary and paleogeographic processes in shaping regional floras.
- Published
- 2023
- Full Text
- View/download PDF
9. Conducting clinical trials in five Eastern European countries (EU-EECs) with a focus on Bulgaria
- Author
-
Tatyana Benisheva, Dimitar Milkov, Valentin Kopanarov, Ivaylo Ivanov, Dimitar Dimitrov, Veselina Todorova, Nigyar Dzhafer, Iva Chavkova, Lyubina Todorova, and Lena Gebert
- Subjects
Clinical trials register ,completed and ongoing clinical trials ,regulatory requirements ,rare disease indication ,distribution by clinical trial phase ,Biotechnology ,TP248.13-248.65 - Abstract
AbstractData for ongoing and completed clinical trials (Phases I-III) were extracted from the European Union Clinical Trials Register for five EU-EECs (Bulgaria, Hungary, Poland, Romania and Slovakia) (from January 1, 2012 to September 30, 2022). Based on the almost 11-year period Poland (n = 4134) and Hungary (n = 3845) represent the largest share of trials, with over 250–300 ongoing and completed clinical trials a year. Bulgaria (with a population of 7 mill. inhabitants) has a lower number of completed and ongoing trials (n = 2049) versus Poland and Hungary, which, however, have much larger populations (Poland − 38 mill., Hungary − 9.8 mill.). Slovakia (5.5 mill. inhabitants), has 67% fewer ongoing and completed clinical trials (n = 1374) than Poland, while Hungary and Bulgaria also have more trials than Slovakia (64% and 33% respectively). The prevalence of trials in all EEC countries was calculated per 100,000 inhabitants, where Hungary (n = 39) ranks first, while Bulgaria (n = 29) is ahead of Slovakia (n = 25), Poland (n = 11) and Romania (n = 5). The ongoing and completed clinical trials conducted in the ten EU-EECs (n = 19030) have shown remarkable expansion over the past decade, accounting for a large share (26.3%) of all EU-wide trials (n = 72215) for the referenced period. The leader of the western EU countries, in terms of trials per 100,000 inhabitants is Denmark (n = 56) followed by Belgium (n = 44), Austria (n = 33), Finland (n = 30) and the Netherlands (n = 30). These results demonstrate that the number of completed and ongoing trials does not correspond to the size of a country’s population.
- Published
- 2023
- Full Text
- View/download PDF
10. Potential of circulating tumour DNA as a biomarker in liquid biopsy
- Author
-
Dimitar Dimitrov, Hristo Ivanov, Nelly Miteva-Marcheva, and Vili Stoyanova
- Subjects
Liquid biopsy ,circulating tumour DNA ,personalized medicine ,Biotechnology ,TP248.13-248.65 - Abstract
AbstractModern oncology has been influenced and transformed by precision and personalized medicine, especially with the introduction of personalized therapy. The ever-increasing knowledge of the genome contributes to the advancement of precision and personalized medicine. Liquid biopsy (LB) is a diagnostic approach with great potential for use in personalized medicine. LB is the isolation and analysis of tumour-derived components such as circulating tumour cells, circulating tumour DNA, circulating tumour RNA and tumour extracellular vesicles. The continuous development of new techniques in the field of LB holds promise for its widespread use. A challenge for scientists is the standardization of these techniques, allowing their application in clinical practice. This review presents the biological characteristics of circulating tumour DNA, popular methods for its detection and analysis, and its potential utility as a biomarker in liquid biopsy.
- Published
- 2023
- Full Text
- View/download PDF
11. Geographic patterns in range sizes and their drivers of endemic angiosperms in China
- Author
-
Yunyun Wang, Tong Lyu, Ao Luo, Dimitar Dimitrov, and Zhiheng Wang
- Subjects
biodiversity conservation ,climate change ,dispersal ability ,geographical distribution ,macro‐evo‐devo ,narrow‐ranged species ,Ecology ,QH540-549.5 - Abstract
Abstract Geographic range size of endemic species is the most important indicator of species' vulnerability to extinction and conservation prioritization, yet variation in range size among species and across space has been relatively understudied. We investigated the variations and geographic patterns of the range size of 9898 angiosperm species endemic to China and compared the effects of historical and contemporary climate and species' functional traits associated with dispersal ability (including growth form, fruit type, and sexual system) on range size variations. Our results revealed that narrow‐ranged endemic species are clustered in Southwest China where angiosperm species' richness peaks. Winter temperature had the strongest and negative effect on the range size of narrow‐ranged endemic species across space and species, while climate seasonality had the strongest and positive effect on the range size of wide‐ranged endemic species. Both historical and contemporary climate have also influenced species range size indirectly via their effects on species' functional traits associated with dispersal ability. Range size of all endemic species, narrow‐ranged and wide‐ranged, showed little phylogenetic signal, suggesting that phylogenetic conservatism plays a minor role in range size variations. Our results show that the range size of angiosperm species endemic to China is driven by both extrinsic spatiotemporal environmental factors and intrinsic species' traits that allow species to cope with environmental change.
- Published
- 2023
- Full Text
- View/download PDF
12. Physicochemical, Antioxidant, and Antimicrobial Properties of Three Medicinal Plants from the Western Part of the Rhodope Mountains, Bulgaria
- Author
-
Albena Parzhanova, Velichka Yanakieva, Ivelina Vasileva, Maria Momchilova, Dimitar Dimitrov, Petya Ivanova, and Yulian Tumbarski
- Subjects
antioxidants ,herbs ,phenolic compounds ,extracts ,antimicrobial activity ,Science - Abstract
The present study examined the physicochemical, antioxidant, and antimicrobial properties of three medicinal plants: thyme (Thymus callieri Borbás ex Velen), cotton thistle (Onopordum acanthium L.), and hawthorn fruit (Crataegus monogyna Jacq.) from the Western Rhodope Mountains, Bulgaria. The first stage determined the physicochemical characteristics (moisture, ash, carbohydrates, proteins, and vitamin C) of the three herbs. The second stage investigated four types of extracts (aqueous, oil, methanolic, and ethanolic) of each herb and evaluated their total phenolic content, the presence of phenolic compounds (flavonoids and phenolic acids), their antioxidant activity, and antimicrobial properties. Thyme was characterised by the highest ash, protein, and vitamin C content (6.62%, 11.30%, and 571 mg/100 g, respectively). Hawthorn fruit showed the highest moisture and carbohydrate content (8.50% and 4.20%, respectively). The 70% ethanolic extracts of the three herbs exhibited the highest levels of phenolic compounds and, consequently, pronounced antioxidant activity, compared to the other three types of extracts. The aqueous, oil, methanolic, and ethanolic thyme extracts demonstrated the highest total phenolic content—TPC (27.20 mg GAE/g, 8.20 mg GAE/g, 31.70 mg GAE/g, and 310.00 mg GAE/g, respectively), compared to the extracts of the other two plants. These results were consistent with the highest antioxidant activity of the thyme extracts determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, the oxygen radical absorbance capacity (ORAC) assay, and the hydroxyl radical averting capacity (HORAC) assay (except for the oil extract examined using the DPPH method). The results from the high-performance liquid chromatography (HPLC) analysis revealed that the flavonoid quercetin-3-ß-glucoside had the highest concentration in thyme (374.5 mg/100 g), while myricetin dominated in the cotton thistle (152.3 mg/100 g). The phenolic acid content analysis showed prevalence of rosmaric acid in the thyme (995 mg/100 g), whereas chlorogenic acid was detected in the highest concentration in the cotton thistle and hawthorn fruit (324 mg/100 g and 27.7 mg/100 g, respectively). The aqueous, methanolic, and ethanolic extracts showed moderate to high antibacterial potential but limited antifungal activity. None of the oil extracts inhibited the test microorganisms used in the study.
- Published
- 2023
- Full Text
- View/download PDF
13. Determination of the antimicrobial activity of lactic acid bacteria isolated from the Black sea mussel Mytilus galloprovincialis Lamarck, 1819
- Author
-
Tsveteslava Ignatova-Ivanova, Sevginar Ibryamova, Darina Bachvarova, Seniha Salim, Simona Valkova, Yoanna Simeonova, Dimitar Dimitrov, Radoslav Ivanov, Nesho Chipev, and Nikolay Natchev
- Subjects
Pharmacy and materia medica ,RS1-441 - Abstract
The present study reports on the determination of the antimicrobial activity of lactic acid bacteria (LAB) isolated from the Black sea mussel Mytilus galloprovincialis Lamarck, 1819. The samples were collected in the period of August 2018 until March 2021. The BIOLOG system was used for microbiological determination. From the mussel M. galloprovincialis Lam. four species of LAB were isolated - Sporolactobacillus kofuensis, Lactobacillus sakei, Streptococcus gallolyticus ss gallolyticus and Lactibacillus brevis. The activity of the strains was determined against test cultures (Escherichia coli 3398, Staphylococus aureus 745, Bacillus subtilis 6633, Salmonella typhimurium 3591, Listeria monocytogens 863 Enterobacter aerogenes 3691, Aspergillus niger, Penicillium claviforme, Saccharomyces cerevisae, Candida albicans 8673 and Candida glabrata 72). Before the analysis for antimicrobial activity, the LAB were cultured in media with different concentrations of sugars - 2, 5 and 10%. The results showed that 4 strains S. kofuensis, L. sakei, S. gallolyticus ss gallolyticus and L. brevis cultured on glucose and oligosaccharides completely lost their activity in all studied variants. Therefore, some carbohydrates (glucose) and oligosaccharides induce the synthesis outside the cell of biologically active molecules, which can probably be attributed to peptides/proteins.
- Published
- 2022
- Full Text
- View/download PDF
14. Spatial Distribution and Genetic Diversity of Turbot (Scophthalmus maximus, Linnaeus, 1758) in Bulgarian Black Sea Waters Relative to Fishing Pressure and Their Abiotic Environment
- Author
-
Ivelina Zlateva, Petya Ivanova, Nina Dzhembekova, Valentina Doncheva, Ivan Popov, Violeta Slabakova, Yordan Raev, Violin Raykov, and Dimitar Dimitrov
- Subjects
Black Sea ,fishing pressure ,genetic diversity ,habitat suitability ,MaxEnt ,spatial distribution ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 ,Oceanography ,GC1-1581 - Abstract
The present study examined the genetic diversity and spatial distribution of turbot (Scophthalmus maximus), an economically important species on the Bulgarian Black Sea coast. Maximum entropy (MaxEnt) modeling software Version 3.4.4. was utilized to develop a habitat suitability model for S. maximus in the Bulgarian Black Sea region. Data collected via demersal and pelagic surveys and genetic sampling from 2017 to 2021 were utilized to link species occurrence localities with selected abiotic factors. Our findings showed that the species’ habitat preferences are strongly influenced by temperature and dissolved oxygen, and projections based on simplified climatic scenarios indicated potential distribution shifts and a substantial reduction in reproduction habitats in the northern region. The assessment of genetic diversity was based on mtDNA COIII sequencing; MtDNA revealed a low level of polymorphism in all analyzed populations. The extensive fishing pressure may have increased the likelihood of genetic and population bottlenecks and a consequent decline in genetic diversity in the Shabla, Nesebar, and Tsarevo populations. The Tajima’s D values for the latter indicated that turbot underwent a bottleneck followed by rapid population expansion. Our findings are essential for the conservation and effective management of S. maximus stocks in the region.
- Published
- 2023
- Full Text
- View/download PDF
15. PHENOLIC CONTENT AND ATIOXIDANT ACTIVITY OF RED GRAPES FROM INTERNATIONAL, LOCAL AND HYBRID GRAPEVINE VARIETIES GROWN IN CENTRAL NORTHERN BULGARIA
- Author
-
Dimitar DIMITROV, Tatyana YONCHEVA, Vanyo HAYGAROV, and Anatoli ILIEV
- Subjects
antioxidant activity ,grapes ,phenols ,free radicals ,grapevine varieties ,Food processing and manufacture ,TP368-456 - Abstract
A study to determine the phenolic content and antioxidant activity of grapes from red international (Cabernet Sauvignon), local (Gamza) and hybrid (Rubin) grapevine varieties grown in the region of Central Northern Bulgaria was conducted. The phenolic content of the grapes, the phenolic content and antioxidant activity of their must were determined. Rubin shown the best content of Total Phenolic Compounds (TPC), Flavonoid Phenolic Compounds (FPC), Non-Flavonoid Phenolic Compounds (NPC) and anthocyanins in the structural elements of the cluster. This hybrid variety also shown the highest content of TPC in the must (0.74±0.00 g/l), followed by Gamza, and the lowest TPC was found in the Cabernet Sauvignon – control variety (0.25±0.00 g/l). The highest amount of anthocyanins was found in Rubin grape must (19.91±0.48 mg/l). The dynamics of increasing of the anthocyanin content in the must of the studied varieties followed the order international variety (Cabernet Sauvignon) < local variety (Gamza) < hybrid variety (Rubin). In the red varieties, the grape must of the Rubin hybrid shown significant and the highest antioxidant activity of the three studied varieties. It was four times higher than that found in the Cabernet Sauvignon control. A correlation between TPC, anthocyanin content and antioxidant activity in Rubin was found. This proved the close connection between the phenolic composition and the antioxidant capacity of the variety. The study proved that the grape must of the two studied hybrid and local varieties shown high biological potential and activities.
- Published
- 2021
16. Editorial: Temporal and Large-Scale Spatial Patterns of Plant Diversity and Diversification
- Author
-
Dimitar Dimitrov, Danilo M. Neves, and Xiaoting Xu
- Subjects
species richness ,environmental gradients ,traits ,macroecology ,macroevolution ,Evolution ,QH359-425 ,Ecology ,QH540-549.5 - Published
- 2022
- Full Text
- View/download PDF
17. Study of the volatile fraction of distillates with added donkey thistle (Onopordum acanthium L.) extracts
- Author
-
Dimitar Dimitrov, Albena Parjanova, and Snezhana Ivanova
- Subjects
volatile compounds ,esters ,higher alcohols ,aldehydes ,terpenes ,Agriculture - Abstract
ethanol extracts of donkey thistle (Onopordum acanthium L.) was conducted. The extracts were added to the pure distillate from the grapes of Melnik-55 grapevine variety in amounts of 20, 50, 80, 100, 200, 400 and 600 ml. The remaining amount to liter was a pure distillate. A distillate of Melnik-55 grapes (without extracts) was used as a control. The addition of 50% ethanol extract of Onopordum acanthium L. increased the total volatile composition of variants 1000:20 and 1000:50, in comparison to the control sample. Higher levels of esters and higher alcohols were found in the same variants. Incorporation of the 50% and 70% ethanol extracts of donkey thistle resulted in increased final total terpene content of the distillates. By increasing the amount of the added 50% ethanol extract, a reduction in the concentrations of acetaldehyde and ethyl acetate was found in the distillates. The basic ester in all the distillates analyzed was ethyl acetate, and the major higher alcohols were 2-methyl-1-butanol, 3-methyl-1-butanol, 1-propanol and 2-butanol. By applying of 50% and 70% ethanol extracts of the plant, a reduction in methanol content in the final distillates was observed. A prospect was the application of 50% ethanol extracts of Onopordum acanthium L, especially variants 1000:20 and 1000:50. This two variants showed higher final levels of aromatic compounds (beverage quality) and slightly higher final levels of terpenes (biological value) compared to the control. The other variants of this group had proven lower levels of methanol (improved toxicological quality) compared to the control.
- Published
- 2021
- Full Text
- View/download PDF
18. Using Kinematic GNSS Data to Assess the Accuracy and Precision of the TanDEM-X DEM Resampled at 1-m Resolution Over the Western Corinth Gulf, Greece
- Author
-
Pierre Briole, Simon Bufferal, Dimitar Dimitrov, Panagiotis Elias, Cyril Journeau, Antonio Avallone, Konstantinos Kamberos, Michel Capderou, and Alexandre Nercessian
- Subjects
Digital elevation model (DEM) ,geophysics ,Global Navigation Satellite Systems (GNSS) ,land applications ,quality control ,surface topography ,Ocean engineering ,TC1501-1800 ,Geophysics. Cosmic physics ,QC801-809 - Abstract
We assess the accuracy and the precision of the TanDEM-X digital elevation model (DEM) of the western Gulf of Corinth, Greece. We use a dense set of accurate ground coordinates obtained by kinematic Global Navigation Satellite Systems (GNSS) observations. Between 2001 and 2019, 148 surveys were made, at a 1 s sampling rate, along highways, roads, and tracks, with a total traveled distance of ∼25 000 km. The data are processed with the online Canadian Spatial Reference System precise point positioning software. From the output files, we select 885 252 coordinates from epochs with theoretical uncertainty below 0.1 m in horizontal and 0.2 m in vertical. Using specific calibration surveys, we estimate the mean vertical accuracy of the GNSS coordinates at 0.2 m. Resampling the DEM by a factor of 10 allows one to compare it with the GNSS in pixels of metric size, smaller than the width of the roads, even the small trails. The best fit is obtained by shifting the DEM by 0.47 ± 0.03 m upward, 0.10 ± 0.1 m westward, and 0.36 ± 0.1 m southward. Those values are 20 times below the nominal resolution of the DEM. Once the shift is corrected, the root mean square deviation between TanDEM-X DEM and GNSS elevations is 1.125 m. In forest and urban areas, the shift between the DEM and the GNSS increases by ∼0.5 m. The metric accuracy of the TanDEM-X DEM paves the way for new applications for long-term deformation monitoring of this area.
- Published
- 2021
- Full Text
- View/download PDF
19. RECORDS OF IXODID TICKS ON WILD BIRDS IN BULGARIA
- Author
-
Nadya Ivanova Aleksandrova, Iva Christova, Dimitar Dimitrov, Martin P Marinov, Elica Panayotova, Iva Trifonova, Evgenia Taseva, Teodora Gladnishka, Galin Kamenov, Mihaela Ilieva, and Pavel Zehtindjiev
- Subjects
Ixodes ricinus ,host preference ,infestation rate ,Infectious and parasitic diseases ,RC109-216 - Abstract
Background: Ixodid ticks are widely studied due to their epidemiological and epizootic importance. It is of great value to know vertebrate host preferences of ticks in order to understand their ecological relationships and distribution. Earlier studies report birds as important hosts of Ixodid tick and a total of 136 ticks species have been frequently found in birds worldwide. However, only few studies related to host preferences of ticks among wild birds in Bulgaria were conducted till now. Aim: To obtain new data on the host preferences of ixodid ticks among wild birds at three locations in Bulgaria. Material and methods: The study was conducted between 2010 – 2020 in three sites in Bulgaria – Biological Experimental Station Kalimok (Silistra region), near Brodilovo village (Burgas region), and the city of Sofia (city park). The birds were caught by mist nets and inspected for ticks. Ticks found were removed by fine tweezers or a special removal tool for ectoparasites. Tick identification was based on external morphological characteristics. Results: A total of 2419 individual birds belonging to 78 species were examined. Of these, 70 individuals (16 species) carried ticks, thus representing 2.9% infestation rate. A total of 262 ticks were collected and identified as: Ixodes ricinus, Hyalomma marginatum, Haemaphysalis punctata, Hae. concinna, Hae. sulcata and two specimens could only be identified to the genus Haemaphysalis. Ixodes ricinus was the most commonly encountered tick (224/262), predominantly nymphs, followed by Hyalomma marginatum (27/262). The highest prevalence of tick infestation was observed among the Eurasian Blackbird, Turdus merula (28.6%), followed by the common nightingale, Luscinia megarhynchos (12.9%) and the common chaffinch, Fringilla coelebs (11.3%). These three bird species harboured the majority of ticks on their heads – some single individuals were infested by 10 up to 25 ticks per bird. Conclusion: Ixodes ricinus was found as the predominant tick species in this study. Nymphs were the most frequently observed stage. Infesting both birds and humans, this tick species has the potential to spread local tick-borne infections.
- Published
- 2021
- Full Text
- View/download PDF
20. Short-Term Hydro-Thermal-Solar Scheduling with CCGT Based on Self-Adaptive Genetic Algorithm
- Author
-
Borche Postolov, Nikolay Hinov, Atanas Iliev, and Dimitar Dimitrov
- Subjects
hydrothermal scheduling ,genetic algorithm ,self-adaptive penalty ,Laplace crossover ,MPTM mutation ,Technology - Abstract
This paper presents a new metaheuristic approach based on a self-adaptive genetic algorithm (SAGA) for solving the short-term hydro-thermal-solar scheduling with combined-cycle (CCGT) units. First of all, the proposed approach is applied to a test system with different characteristics, considering the valve-point effect. The simulation results obtained from the new SAGA are compared with the results obtained from some other metaheuristic methods, such as AIS, DE, and EP to reveal the validity and verify the feasibility of the proposed approach. The test results show that the proposed metaheuristic approach proves the effectiveness and superiority of the SAGA algorithm for solving the short-term hydro-thermal-solar scheduling (SHTSS) problem.
- Published
- 2022
- Full Text
- View/download PDF
21. STATISTICAL ANALYSIS OF THE RESULTS OF TRANS-RESVERATROL CONTENT IN GRAPES OF HYBRID BULGARIAN GRAPE VARIETIES
- Author
-
Vanyo HAYGAROV, Tatyana YONCHEVA, Dimitar DIMITROV, and Emil TSVETANOV
- Subjects
grapes ,wine ,chemical composition ,resveratrol ,intraspecific and interspecific hybridization ,Food processing and manufacture ,TP368-456 - Abstract
A study for statistical analysis of the results of the trans-resveratrol content in grapes of hybrid Bulgarian vine varieties was carried out. The chemical composition of the grapes was analyzed. Excellent technological grapes maturity (194.33 ± 19.13 g/dm3 - 244.00 ± 20.80 g/dm3 of accumulated sugars) was achieved. The detected ranges of titratable acids (5.66 ± 0.25 g/dm3 - 7.05 ± 0.33 g/dm3), tartaric acid (3.04 ± 0.15 g/dm3 - 4.66 ± 0.25 g/dm3), malic acid (4.42 ± 0.27 g/dm3 - 6.33 ± 0.15 g/dm3) and pH (3.24 ± 0.03 - 3.60 ± 0.32) were typical for grapes obtained from vines grown in the region of the Danube Plain, Central Northern Bulgaria. Trans-resveratrol was found in the highest amount (3.52 ± 0.59 mg/dm3) in the Kaylashki rubin grapes. Its content was close to this (3.46 ± 0.40 mg/dm3) of the control variety Pinot Noir. The lowest (1.78 ± 0.17 mg/dm3) was the amount of trans-resveratrol in the grapes of Storgozia variety. The statistical processing divided the varities into two groups (by trans-resveratrol content): the first group had higher trans-resveratrol content and included the varieties Kaylashki Rubin (3.52 ± 0.59 mg/dm3), Bouquet (3.18 ± 0.15mg/dm3) and Pinot Noir (3.46±0.40 mg/dm3); the second group consisting of the varieties Rubin (2.40±0.09 mg/dm3), Trapezitsa (2.30±0.80 mg/dm3) and Storgozia (1.78±0.17 mg/dm3) with lower trans-resveratrol content.
- Published
- 2019
22. Gold-Based Catalysts for Complete Formaldehyde Oxidation: Insights into the Role of Support Composition
- Author
-
Lyuba Ilieva, Dimitar Dimitrov, Elitsa Kolentsova, Anna Maria Venezia, Daniela Karashanova, Georgi Avdeev, Petya Petrova, Razvan State, and Tatyana Tabakova
- Subjects
gold catalysts ,HCHO oxidation ,Co3O4-CeO2 mixed oxides ,mechanochemical preparation ,potassium modification ,Chemical technology ,TP1-1185 ,Chemistry ,QD1-999 - Abstract
Formaldehyde (HCHO) is recognized as one of the most emitted indoor air pollutants with high detrimental effect on human health. Significant research efforts are focused on HCHO removal to meet emission regulations in an effective and economically profitable way. For over three decades, the unique electronic properties and catalytic abilities of nano-gold catalysts continue to be an attractive research area for the catalytic community. Recently, we reported that mechanochemical mixing is a relevant approach to the preparation of Co-Ce mixed oxides with high activity in complete benzene oxidation. A trend of higher surface defectiveness, in particular, oxygen vacancies, caused by close interaction between cobalt oxide and cerium oxide phases, was observed for a mixed oxide composition of 70 wt.% Co3O4 and 30 wt.% CeO2. These results directed further improvement by promotion with gold and optimization of mixed oxide composition, aiming for the development of an efficient catalyst for room temperature HCHO abatement. Support modification with potassium was studied; however, the K addition caused less enhancement of HCHO oxidation activity than expected. This motivated the preparation of new carrier material. In addition to Co3O4-CeO2 mixed metal oxides with preset ratio, γ-Al2O3 intentionally containing 33% boehmite and shortly named Al2O3-b was used for synthesis. Analysis of the role of support composition in HCHO oxidation was based on the characterization of nano-gold catalysts by textural measurements, XRD, HRTEM, XPS, and TPR techniques. Gold supported on mechanochemically treated Co3O4-CeO2-Al2O3-b (50 wt.% Al2O3-b) exhibited superior activity owing to high Ce3+ and Co3+ surface amounts and the most abundant oxygen containing species with enhanced mobility. This catalyst achieved oxidation to CO2 and H2O by 95% HCHO conversion at room temperature and 100% at 40 °C, thus implying the potential of this composition in developing efficient catalytic materials for indoor air purification.
- Published
- 2022
- Full Text
- View/download PDF
23. The phylogeny of pholcid spiders: a critical evaluation of relationships suggested by molecular data (Araneae, Pholcidae)
- Author
-
Bernhard A. Huber, Jonas Eberle, and Dimitar Dimitrov
- Subjects
Zoology ,QL1-991 - Abstract
With almost 600 species, the latest molecular phylogeny of pholcid spiders (Eberle et al. 2018, BMC Evolutionary Biology) more than triples the largest previously available molecular phylogeny of the family. At the level of genera, the coverage is high (86%, i.e., 75 of the 87 named genera), and at the level of subfamilies it is complete. The present paper is an effort to critically evaluate the implications of this phylogeny for pholcid systematics. The analyses largely support the division of Pholcidae into five subfamilies: Ninetinae, Arteminae, Modisiminae, Smeringopinae, and Pholcinae. Their compositions are largely unchanged except that Chisosa Huber, 2000 is moved from Ninetinae to Arteminae. The positions of Artema Walckenaer, 1837 and Priscula Simon, 1893 in this system remain dubious. Relationships among subfamilies remain weakly supported, except for the sister group relationship between Smeringopinae and Pholcinae. Several major clades within subfamilies are separated from each other along geographical boundaries; for example within Modisiminae a South American clade and a Central + North American + Caribbean clade, and within Smeringopinae a Sub-Saharan clade and a clade ranging from the Mediterranean to Central Asia. Central + North American + Caribbean clades in both Ninetinae and Modisiminae may originate from South American ancestors. Many taxonomic changes are suggested by the data, some of which are formally implemented herein. Two new genera result from the splitting of Calapnita Simon, 1892 and Panjange Deeleman-Reinhold & Deeleman, 1983, respectively: Nipisa Huber, gen. n.; and Apokayana Huber, gen. n. Nine new genera result from splitting of Pholcus: Cantikus Huber, gen. n.; Kelabita Huber, gen. n.; Kintaqa Huber, gen. n.; Muruta Huber, gen. n.; Meraha Huber, gen. n.; Paiwana Huber, gen. n.; Pribumia Huber, gen. n.; Teranga Huber, gen. n.; and Tissahamia Huber, gen. n. Two genera are newly synonymized: Platnicknia Özdikmen & Demir, 2009 is synonymized with Modisimus Simon, 1893; Sihala Huber, 2011 is synonymized with Pholcus Walckenaer, 1805. Pholcus agadir Huber, 2011 is moved to Micropholcus Deeleman-Reinhold & Prinsen, 1987, resulting in the new combination Micropholcus agadir (Huber, 2011).
- Published
- 2018
- Full Text
- View/download PDF
24. Microhabitat change drives diversification in pholcid spiders
- Author
-
Jonas Eberle, Dimitar Dimitrov, Alejandro Valdez-Mondragón, and Bernhard A. Huber
- Subjects
Microhabitat ,Diversification rates ,Speciation ,Leaf dwelling ,Pholcidae ,Phylogeny ,Evolution ,QH359-425 - Abstract
Abstract Background Microhabitat changes are thought to be among the main drivers of diversification. However, this conclusion is mostly based on studies on vertebrates. Here, we investigate the influence of microhabitat on diversification rates in pholcid spiders (Araneae, Pholcidae). Diversification analyses were conducted in the framework of the largest molecular phylogeny of pholcid spiders to date based on three nuclear and three mitochondrial loci from 600 species representing more than 85% of the currently described pholcid genera. Results Assessments of ancestral microhabitat revealed frequent evolutionary change. In particular, within the largest subfamily Pholcinae, numerous changes from near-ground habitats towards leaves and back were found. In general, taxa occupying leaves and large sheltered spaces had higher diversification rates than ground-dwelling taxa. Shifts in speciation rate were found in leaf- and space-dwelling taxa. Conclusions Our analyses result in one of the most comprehensive phylogenies available for a major spider family and provide a framework for any subsequent studies of pholcid spider biology. Diversification analyses strongly suggest that microhabitat is an important factor influencing diversification patterns in pholcid spiders.
- Published
- 2018
- Full Text
- View/download PDF
25. ABOUT THE NEED FOR PERFORMING TRAINING AND INCREASING THE QUALIFICATION OF DISPATCHERS AND MOVEMENT MANAGERS IN RAILWAY TRANSPORT
- Author
-
Dimitar Dimitrov and Zlatin Trendafilov
- Subjects
transport ,traffic ,railway infrastructure ,dispatching system ,train movement management ,information systems ,Economics as a science ,HB71-74 - Abstract
The modern movement of trains in railway transport is a high-tech process related to the management of their movement through modern technical and information systems. The construction and modernization of these systems is cyclical and usually coincides with the rehabilitation and modernization of railway transport. These systems mainly employ mid and high management staff, namely traffic managers and train dispatchers of the respective railway sections. This publication discusses the contemporary aspects and perspectives for carrying out professional training and enhancing the qualifications of traffic managers and train dispatchers in railway transport. In fulfilling this objective, the functional characteristics, parameters and capabilities of the implemented concrete systems are taken into account, namely the company "TALES", which has implemented several projects in Bulgaria in recent years.
- Published
- 2018
- Full Text
- View/download PDF
26. Statistical Assessment of Fluvisols in 'Gladino' Gravel Quarry, Chelopechene, Bulgaria
- Author
-
Vladimir Ilinkin, Peter Zhelev, and Dimitar Dimitrov
- Subjects
uvisols ,Physicochemical properties ,statistical assessment ,gravel quarry ,Science ,Agriculture - Abstract
e paper presents results of an investigation on Fluvisols. The soils are located in “Gladino” gravel quarry, Chepintsy district, Bulgaria, on an area of 1.043 km2.Soil samples were taken from fifteen soil profiles at a depth of 0-100 cm. The factors of soil formation were characterized and it`s physicochemical properties were studied. The changes in physicochemical properties were investigated at different soil depths and the relationships between different soil characteristics were tested by correlation analysis. The results reveal that some soil characteristics, such as the content of clay, sand, organic matter, and the soil porosity have strong positive or negative correlation with the soil depth. The soil characteristics such as acidity or alkalinity of soil (pH), the content of loam, bulk density, Total Kjeldal Nitrogen (TKN), mobile phosphorus and potassium demonstrated an insignificant or weak relationship with the soil depth. There are significant correlations between the physicochemical soil properties in 28 out of 78 cases. All results are discussed in relation to soil formation processes in the studied region.
- Published
- 2017
- Full Text
- View/download PDF
27. Notes about the floristic diversity in the Triglav National Park and the vascular flora of the towns of Budva, Podgorica and Dubrovnik (Adriatic Coast of Croatia and Montenegro)
- Author
-
Dimitar Dimitrov and Vasil Vutov
- Subjects
julian alps ,mediterranean flora ,protected area ,Science - Abstract
This article describes the flora of the northern slopes of the Triglav Peak (Julian Alps). Further, we discuss the flora of Dubrovnik (the old town area) and the flora of the towns of Budva and Podgoritsa.
- Published
- 2017
28. Contrasting Biogeographic Patterns of Bacterial and Archaeal Diversity in the Top- and Subsoils of Temperate Grasslands
- Author
-
Nana Liu, Huifeng Hu, Wenhong Ma, Ye Deng, Yuqing Liu, Baihui Hao, Xinying Zhang, Dimitar Dimitrov, Xiaojuan Feng, and Zhiheng Wang
- Subjects
biogeographic patterns ,topsoil ,subsoil ,bacteria ,archaea ,historical temperature anomaly ,Microbiology ,QR1-502 - Abstract
ABSTRACT Biogeographic patterns and drivers of soil microbial diversity have been extensively studied in the past few decades. However, most research has focused on the topsoil, while the subsoil is assumed to have microbial diversity patterns similar to those of the topsoil. Here we compared patterns and drivers of microbial alpha and beta diversity in and between topsoils (0 to 10 cm) and subsoils (30 to 50 cm) of temperate grasslands in Inner Mongolia of China, covering an ∼1,500-km transect along an aridity gradient. Counter to the conventional assumption, we find contrasting biogeographic patterns of diversity and influencing factors for different bacterial and archaeal groups and between depths. While bacterial diversity remains constant or increases with increasing aridity in topsoil and decreases in subsoil, archaeal diversity decreases in topsoil and remains constant in subsoil. Microbial diversity in the topsoil is most strongly influenced by aboveground vegetation and contemporary climate but is most strongly influenced by the factor historical temperature anomaly since the Last Glacial Maximum (LGM) and by soil pH in the subsoil. Moreover, the biogeographic patterns of topsoil-subsoil community dissimilarities vary for different microbial groups and are overall most strongly influenced by soil fertility differences between depths for bacteria and by contemporary climate for archaea. These findings suggest that diversity patterns observed in the topsoil may not be readily applied to the subsoil horizons. For the subsoil in particular, historical climate plays a vital role in the spatial variation of bacterial diversity. Overall, our study provides novel information for understanding and predicting soil microbial diversity patterns at depth. IMPORTANCE Exploring the biogeographic patterns of soil microbial diversity is critical for understanding mechanisms underlying the response of soil processes to climate change. Using top- and subsoils from an ∼1,500-km temperate grassland transect, we find divergent patterns of microbial diversity and its determinants in the topsoil versus the subsoil. Furthermore, we find important and direct legacy effects of historical climate change on the microbial diversity of subsoil yet indirect effects on topsoil. Our findings challenge the conventional assumption of similar geographic patterns of soil microbial diversity along soil profiles and help to improve our understanding of how soil microbial communities may respond to future climate change in different regions with various climate histories.
- Published
- 2019
- Full Text
- View/download PDF
29. Biting midges (Culicoides, Diptera) transmit Haemoproteus parasites of owls: evidence from sporogony and molecular phylogeny
- Author
-
Dovilė Bukauskaitė, Rita Žiegytė, Vaidas Palinauskas, Tatjana A. Iezhova, Dimitar Dimitrov, Mikas Ilgūnas, Rasa Bernotienė, Mikhail Yu. Markovets, and Gediminas Valkiūnas
- Subjects
Haemosporidian parasites ,Haemoproteus ,Owls ,Sporogony ,Culicoides ,Vectors ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Haemoproteus parasites are widespread, and several species cause diseases both in birds and blood-sucking insects. These pathogens are transmitted by dipterans belonging to the Ceratopogonidae and Hippoboscidae, however certain vector species remain unknown for the majority of Haemoproteus spp. Owls are often infected by Haemoproteus parasites, but experimental studies on vectors of these infections are lacking. The aim of this study was to investigate sporogonic development of two widespread Haemoproteus parasites of owls, H. noctuae and H. syrnii in experimentally infected biting midges Culicoides impunctatus and Culicoides nubeculosus. We also followed in vitro sporogonic development of these infections and determined their phylogenetic relationships with Haemoproteus spp., for which vectors have been identified. Methods Wild-caught C. impunctatus and laboratory reared C. nubeculosus were infected experimentally by allowing them to take blood meals on one individual long-eared owl (Asio otus) and one tawny owl (Strix aluco) harbouring mature gametocytes of H. noctuae (lineage hCIRCUM01) and H. syrnii (hCULCIB01), respectively. The engorged insects were maintained in the laboratory at 16–18 °C, and dissected at intervals in order to follow the development of ookinetes, oocysts and sporozoites. We also observed in vitro development of sexual stages of both parasites by exposure of infected blood to air. The parasite lineages were determined by polymerase chain reaction-based methods. Bayesian phylogeny was constructed in order to determine the relationships of owl parasites with other avian Haemoproteus spp., for which vectors have been identified. Results Both H. noctuae and H. syrnii completed sporogony in C. nubeculosus, and H. noctuae completed sporogony in C. impunctatus. Ookinetes, oocysts and sporozoites of these parasites were reported and described. Gametes and ookinetes of both species readily developed in vitro. In accordance with sporogony data, the phylogenetic analysis placed both parasite lineages in a clade of Culicoides spp.-transmitted avian Haemoproteus (Parahaemoproteus) spp. Conclusions Culicoides nubeculosus and C. impunctatus are vectors of H. noctuae and H. syrnii. Phylogenies based on cytochrome b gene indicate parasite-vector relationships, and we recommend using them in predicting possible parasite-vector relationships and planning research on avian Haemoproteus spp. vectors in wildlife.
- Published
- 2015
- Full Text
- View/download PDF
30. Presynaptic morphology and vesicular composition determine vesicle dynamics in mouse central synapses
- Author
-
Laurent Guillaud, Dimitar Dimitrov, and Tomoyuki Takahashi
- Subjects
presynaptic terminal ,synaptic vesicle ,mobility ,morphology ,vesicular glutamate transporter ,microtubule ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
Transport of synaptic vesicles (SVs) in nerve terminals is thought to play essential roles in maintenance of neurotransmission. To identify factors modulating SV movements, we performed real-time imaging analysis of fluorescently labeled SVs in giant calyceal and conventional hippocampal terminals. Compared with small hippocampal terminals, SV movements in giant calyceal terminals were faster, longer and kinetically more heterogeneous. Morphological maturation of giant calyceal terminals was associated with an overall reduction in SV mobility and displacement heterogeneity. At the molecular level, SVs over-expressing vesicular glutamate transporter 1 (VGLUT1) showed higher mobility than VGLUT2-expressing SVs. Pharmacological disruption of the presynaptic microtubule network preferentially reduced long directional movements of SVs between release sites. Functionally, synaptic stimulation appeared to recruit SVs to active zones without significantly altering their mobility. Hence, the morphological features of nerve terminals and the molecular signature of vesicles are key elements determining vesicular dynamics and movements in central synapses.
- Published
- 2017
- Full Text
- View/download PDF
31. Chemometric Evaluation of the Link between Acute Toxicity, Health Issues and Physicochemical Properties of Silver Nanoparticles
- Author
-
Miroslava Nedyalkova, Dimitar Dimitrov, Borjana Donkova, and Vasil Simeonov
- Subjects
nanoparticles ,silver ,physicochemical properties ,acute toxicity ,chemometrics ,Mathematics ,QA1-939 - Abstract
The present study’s objective is to focus on some developments in the field of statistical models of a complex system, like nanoparticles responses in the environmental media. An important problem that still needs to be studied and interpreted is the relations between physicochemical parameters of the nanoparticles like primary size, primary hydrophobic diameter, zeta potential, etc. with respective toxicity values. It holds true especially for silver nanoparticle systems due to their known bactericidal effect and wide distribution in practice. The present study deals with the data for physicochemical and toxicity parameters of 94 different silver nanoparticle systems in order to reveal specific relations between physicochemical properties and acute toxicity readings using multivariate statistical methods. Searching for these specific relationships between physicochemical parameters and toxicity responses is the novel element in the present study. This has focused our study toward developing a model that describes the relationship between physicochemical properties and toxicity of silver NPs based on a dataset gathered from the literature. It is shown that the systems studied could be divided into four patterns (clusters) of similarity depending not only on the physicochemical indicators related to particles size but also by their acute toxicity. The acute toxicity is strongly correlated to the zeta potential of the particles if the whole data set is considered.
- Published
- 2019
- Full Text
- View/download PDF
32. A review and phylogeny of Scarabaeine dung beetle fossils (Coleoptera: Scarabaeidae: Scarabaeinae), with the description of two Canthochilum species from Dominican amber
- Author
-
Sergei Tarasov, Fernando Z. Vaz-de-Mello, Frank-Thorsten Krell, and Dimitar Dimitrov
- Subjects
Dung beetles ,Scarabaeinae ,Canthochilum ,New species ,Fossils ,Phylogeny ,Medicine ,Biology (General) ,QH301-705.5 - Abstract
Despite the increasing rate of systematic research on scarabaeine dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae), their fossil record has remained largely unrevised. In this paper, we review all 33 named scarabaeine fossils and describe two new species from Dominican amber (Canthochilum alleni sp.n., Canthochilum philipsivieorum sp.n.). We provide a catalogue of all fossil Scarabaeinae and evaluate their assignment to this subfamily, based primarily on the original descriptions but also, where possible, by examining the type specimens. We suggest that only 21 fossil taxa can be reliably assigned to the Scarabaeinae, while the remaining 14 should be treated as doubtful Scarabaeinae. The doubtful scarabaeines include the two oldest dung beetle fossils known from the Cretaceous and we suggest excluding them from any assessments of the minimum age of scarabaeine dung beetles. The earliest reliably described scarabaeine fossil appears to be Lobateuchus parisii, known from Oise amber (France), which shifts the minimum age of the Scarabaeinae to the Eocene (53 Ma). We scored the best-preserved fossils, namely Lobateuchus and the two Canthochilum species described herein, into the character matrix used in a recent morphology-based study of dung beetles, and then inferred their phylogenetic relationships with Bayesian and parsimony methods. All analyses yielded consistent phylogenies where the two fossil Canthochilum are placed in a clade with the extant species of Canthochilum, and Lobateuchus is recovered in a clade with the extant genera Ateuchus and Aphengium. Additionally, we evaluated the distribution of dung beetle fossils in the light of current global dung beetle phylogenetic hypotheses, geological time and biogeography. The presence of only extant genera in the late Oligocene and all later records suggests that the main present-day dung beetle lineages had already been established by the late Oligocene–mid Miocene.
- Published
- 2016
- Full Text
- View/download PDF
33. SemEval-2024 Task 4: Multilingual Detection of Persuasion Techniques in Memes.
- Author
-
Dimitar Dimitrov, Firoj Alam, Maram Hasanain, Abul Hasnat 0001, Fabrizio Silvestri, Preslav Nakov, and Giovanni Da San Martino
- Published
- 2024
- Full Text
- View/download PDF
34. Mirela at CheckThat! 2024: Check-worthiness of Tweets with Multilingual Embeddings and Adversarial Training.
- Author
-
Mirela Dryankova, Dimitar Dimitrov, Ivan Koychev, and Preslav Nakov
- Published
- 2024
35. Overview of the CLEF-2024 CheckThat! Lab Task 2 on Subjectivity in News Articles.
- Author
-
Julia Maria Struß, Federico Ruggeri, Alberto Barrón-Cedeño, Firoj Alam, Dimitar Dimitrov, Andrea Galassi, Georgi Pachov, Ivan Koychev, Preslav Nakov, Melanie Siegel, Michael Wiegand, Maram Hasanain, Reem Suwaileh, and Wajdi Zaghouani
- Published
- 2024
36. Overview of the CLEF-2024 CheckThat! Lab Task 3 on Persuasion Techniques.
- Author
-
Jakub Piskorski, Nicolas Stefanovitch, Firoj Alam, Ricardo Campos 0001, Dimitar Dimitrov, Alípio Jorge, Senja Pollak, Nikolay Ribin, Zoran Fijavz, Maram Hasanain, Purificação Silvano, Elisa Sartori, Nuno Guimarães, Ana Zwitter Vitez, Ana Filipa Pacheco, Ivan Koychev, Nana Yu, Preslav Nakov, and Giovanni Da San Martino
- Published
- 2024
37. Dissecting Paraphrases: The Impact of Prompt Syntax and supplementary Information on Knowledge Retrieval from Pretrained Language Models.
- Author
-
Stephan Linzbach, Dimitar Dimitrov 0002, Laura Kallmeyer, Kilian Evang, Hajira Jabeen, and Stefan Dietze
- Published
- 2024
- Full Text
- View/download PDF
38. EXAMS-V: A Multi-Discipline Multilingual Multimodal Exam Benchmark for Evaluating Vision Language Models.
- Author
-
Rocktim Jyoti Das, Simeon Emilov Hristov, Haonan Li 0002, Dimitar Dimitrov, Ivan Koychev, and Preslav Nakov
- Published
- 2024
- Full Text
- View/download PDF
39. Beyond Facts: 4th International Workshop on Computational Methods for Online Discourse Analysis.
- Author
-
Konstantin Todorov, Pavlos Fafalios, Stefan Dietze, and Dimitar Dimitrov 0002
- Published
- 2024
- Full Text
- View/download PDF
40. Analyzing Security and Privacy Advice During the 2022 Russian Invasion of Ukraine on Twitter.
- Author
-
Juliane Schmüser, Harshini Sri Ramulu, Noah Wöhler, Christian Stransky, Felix Bensmann, Dimitar Dimitrov 0002, Sebastian Schellhammer, Dominik Wermke, Stefan Dietze, Yasemin Acar, and Sascha Fahl
- Published
- 2024
- Full Text
- View/download PDF
41. Multiple-Projectile Penetrating Neck Injury from a Modified Nail-Containing Gas Pistol
- Author
-
Dimitar Dimitrov Pazardzhikliev
- Subjects
Gas pistol ,neck injury ,penetrating ,Medicine - Abstract
Background: Penetrating neck injuries result from missiles and stab wounds. A gas pistol is a non-lethal weapon for self-defence. Case Report: We present a case where the use of a modified gun led to multiple injuries in a single shot. Four projectiles were embedded in the neck, one in the larynx and three in the cervical spine. The first was removed via a combined external and endoscopic approach, while the rest were put on follow-up. Conclusion: The reported case shows that damage from modified gas pistols, although rarely life threatening, may cause long term discomfort and diminished quality of life.
- Published
- 2014
- Full Text
- View/download PDF
42. A Conceptual Generalized Nets Immunological Model for Agent based Exploration of Unknown Environment
- Author
-
Zlatogor Minchev and Dimitar Dimitrov
- Subjects
Generalized nets ,Artificial immune networks ,Agents ,Multiagent systems ,Exploration ,Unknown environment ,Smart Homes ,Energy saving ,Biology (General) ,QH301-705.5 - Abstract
Exploration of unknown environment in general is a very broad area, which in the current paper is addressed more to the agent based idea and robotics. As far as the agent and its further development - multiagent modus resembles real social systems the interaction between agents could benefit from the natural mechanisms like immune system. The paper presents a conceptual model for exploration of unknown environment, which extends the immune networks' idea with some self-immunization by means of dynamic anti-body generation with application both in mobile and i-mobile robotics (Smart Homes) modeling and control, maintaining practical benefits like energy saving. The model is described in terms of the Generalized Nets Theory, thus providing a convenient and natural environment for agent-based modeling.
- Published
- 2010
43. Why do tropical mountains support exceptionally high biodiversity? The Eastern Arc mountains and the drivers of Saintpaulia diversity.
- Author
-
Dimitar Dimitrov, David Nogués-Bravo, and Nikolaj Scharff
- Subjects
Medicine ,Science - Abstract
We combine information about the evolutionary history and distributional patterns of the genus Saintpaulia H. Wendl. (Gesneriaceae; 'African violets') to elucidate the factors and processes behind the accumulation of species in tropical montane areas of high biodiversity concentration. We find that high levels of biodiversity in the Eastern Arc Mountains are the result of pre-Quaternary speciation processes and environmental stability. Our results support the hypothesis that climatically stable mountaintops may have acted as climatic refugia for lowland lineages during the Pleistocene by preventing extinctions. In addition, we found evidence for the existence of lowland micro-refugia during the Pleistocene, which may explain the high species diversity of East African coastal forests. We discuss the conservation implications of the results in the context of future climate change.
- Published
- 2012
- Full Text
- View/download PDF
44. Second and third generation voltage-sensitive fluorescent proteins for monitoring membrane potential
- Author
-
Amelie Perron, Hiroki Mutoh, Walther Akemann, Sunita Ghimire, Dimitar Dimitrov, Yuka Iwamoto, and Thomas Knopfel
- Subjects
optical imaging ,patch clamp ,fluorescence ,fluorescent proteins ,Genetically-encoded voltage sensors ,neuronal circuit dynamics ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Over the last decade, optical neuroimaging methods have been enriched by engineered biosensors derived from fluorescent protein (FP) reporters fused to protein detectors that convert physiological signals into changes of intrinsic FP fluorescence. These FP-based indicators are genetically encoded, and hence targetable to specific cell populations within networks of heterologous cell types. Among this class of biosensors, the development of optical probes for membrane potential is both highly desirable and challenging. A suitable FP voltage sensor would indeed be a valuable tool for monitoring the activity of thousands of individual neurons simultaneously in a non-invasive manner. Previous prototypic genetically-encoded FP voltage indicators achieved a proof of principle but also highlighted several difficulties such as poor cell surface targeting and slow kinetics. Recently, we developed a new series of FRET-based Voltage-Sensitive Fluorescent Proteins (VSFPs), referred to as VSFP2s, with efficient targeting to the plasma membrane and high responsiveness to membrane potential signaling in excitable cells. In addition to these FRET-based voltage sensors, we also generated a third series of probes consisting of single FPs with response kinetics suitable for the optical imaging of fast neuronal signals. These newly available genetically-encoded reporters for membrane potential will be instrumental for future experimental approaches directed toward the understanding of neuronal network dynamics and information processing in the brain. Here, we review the development and current status of these novel fluorescent probes.
- Published
- 2009
- Full Text
- View/download PDF
45. Spectrally-resolved response properties of the three most advanced FRET based fluorescent protein voltage probes.
- Author
-
Hiroki Mutoh, Amelie Perron, Dimitar Dimitrov, Yuka Iwamoto, Walther Akemann, Dmitriy M Chudakov, and Thomas Knöpfel
- Subjects
Medicine ,Science - Abstract
Genetically-encoded optical probes for membrane potential hold the promise of monitoring electrical signaling of electrically active cells such as specific neuronal populations in intact brain tissue. The most advanced class of these probes was generated by molecular fusion of the voltage sensing domain (VSD) of Ci-VSP with a fluorescent protein (FP) pair. We quantitatively compared the three most advanced versions of these probes (two previously reported and one new variant), each involving a spectrally distinct tandem of FPs. Despite these different FP tandems and dissimilarities within the amino acid sequence linking the VSD to the FPs, the amplitude and kinetics of voltage dependent fluorescence changes were surprisingly similar. However, each of these fluorescent probes has specific merits when considering different potential applications.
- Published
- 2009
- Full Text
- View/download PDF
46. Engineering of a genetically encodable fluorescent voltage sensor exploiting fast Ci-VSP voltage-sensing movements.
- Author
-
Alicia Lundby, Hiroki Mutoh, Dimitar Dimitrov, Walther Akemann, and Thomas Knöpfel
- Subjects
Medicine ,Science - Abstract
Ci-VSP contains a voltage-sensing domain (VSD) homologous to that of voltage-gated potassium channels. Using charge displacement ('gating' current) measurements we show that voltage-sensing movements of this VSD can occur within 1 ms in mammalian membranes. Our analysis lead to development of a genetically encodable fluorescent protein voltage sensor (VSFP) in which the fast, voltage-dependent conformational changes of the Ci-VSP voltage sensor are transduced to similarly fast fluorescence read-outs.
- Published
- 2008
- Full Text
- View/download PDF
47. Engineering and characterization of an enhanced fluorescent protein voltage sensor.
- Author
-
Dimitar Dimitrov, You He, Hiroki Mutoh, Bradley J Baker, Lawrence Cohen, Walther Akemann, and Thomas Knöpfel
- Subjects
Medicine ,Science - Abstract
BackgroundFluorescent proteins have been used to generate a variety of biosensors to optically monitor biological phenomena in living cells. Among this class of genetically encoded biosensors, reporters for membrane potential have been a particular challenge. The use of presently known voltage sensor proteins is limited by incorrect subcellular localization and small or absent voltage responses in mammalian cells.ResultsHere we report on a fluorescent protein voltage sensor with superior targeting to the mammalian plasma membrane and high responsiveness to membrane potential signaling in excitable cells.Conclusions and significanceThis biosensor, which we termed VSFP2.1, is likely to lead to new methods of monitoring electrically active cells with cell type specificity, non-invasively and in large numbers, simultaneously.
- Published
- 2007
- Full Text
- View/download PDF
48. Modular Synthesis of Efficient Quantum Uncomputation.
- Author
-
Hristo Venev, Timon Gehr, Dimitar Dimitrov, and Martin T. Vechev
- Published
- 2024
- Full Text
- View/download PDF
49. Gpachov at CheckThat!-2023: A Diverse Multi-approach Ensemble for Subjectivity Detection in News Articles.
- Author
-
Georgi Pachov, Dimitar Dimitrov, Ivan Koychev, and Preslav Nakov
- Published
- 2023
50. Challenges of Metaverse in Education Digitalization.
- Author
-
Dimiter Velev, Dimitar Dimitrov, and Plamena Zlateva
- Published
- 2023
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.