We discuss the influence of the type of β-diketone ancillary ligand in Iridium (III) bis phenyl-benzothiazole complexes ((bt)2Ir(β-diketone)) on their photophysical and electroluminescent properties when they are used as dopants in white organic light-emitting diodes (WOLED). For this purpose, we investigated four novel yellow cyclometalated complexes: (bt)2Ir(dbm), (bt)2Ir(fmtdbm), (bt)2Ir(tta) and (bt)2Ir(bsm), where dbm = 1,3-diphenylpropane-1,3-dionate; fmtdbm = 1-(4-fluorophenyl)-3-(4-methoxyphenyl)propane-1,3-dionate; tta = 4,4,4-trifluoro-1-(thiophene-2-yl)butane-1,3-dionate; and bsm = 1-phenylicosane-1,3-dionate). To obtain white light by mixing emissions of two complementary colors (yellow emitted by the dopant and blue, by another emitter), we chose the following OLED structure: ITO/doped HTL/ElL/ETL/M, where ITO was a transparent anode of In2O3:SnO2; M, a metallic Al cathode; HTL, 4,4'-Bis(9H-carbazol-9-yl)biphenyl (CBP) involved in a poly(N-vinylcarbazole) (PVK) matrix; ElL, an electroluminescent layer of aluminum(III)bis(2-methyl-8-quninolinato)-4-phenylphenolate (BAlq); and ETL, an electron-transporting layer of zinc(II)bis(2-2-hydroxyphenyl)benzothiazole. We found that all complexes are suitable candidates for fabrication of WOLED. The best results were demonstrated by the device doped with 2 wt % of (bt)2Ir(bsm), which had twice as high luminescence (1100 cd/m2) and one-and-a-half as high current efficiency (5 cd/A) as the device doped with 1.25 wt % of the known (bt)2Ir(acac), with its 580 cd/m2 and 3.4 cd/A at approximately the same CIE (Commission Internationale de L'Eclairage) (x/y) coordinates of the warm white light emitted by the two devices.
This article presents the initial results of the 3D monitoring of West Pirin Fault in the area of the village of Brezhani, SW Bulgaria. The monitoring equipment – extensometer TM71 was installed in August 2013. The data obtained from the observations until November 2018 were processed. The results show 5 stages in the dynamics of this part of the fault. One of them is associated with a coseismic effect (sharp movements) resulted from a local weak seismic event. The obtained results show that Y-axis movements are most stable, representing right-lateral strike-slip movements with a high correlation of data (coefficient of determination r2=0.866). The most active movements have been established during the last 2 years of the observations. In 2017-2018, the established rate of right-lateral strike-slip (Y axis) is 0.84 mm/a. For whole observation period the results show compression od fault zone 0.07 mm/a, right-lateral strike-slip 0.61 mm/a and reverse movements 0.09 mm/a. These results give us reason to suppose a recent activity along West Pirin Fault.
The common historical background between geology and medicine is rich in research opportunities, so the current scientific development in the field can prove to be both a useful resource and an incentive for further research and development. The main task of medical geology is to study the impact of the geological environment and related processes on the health of people and animals. Globally, it is a dynamically developing discipline bringing together the geoscience, biomedical, and public health communities to address a wide range of environmental health problems. Unfortunately, Bulgaria lacks a scientific direction in that field. The purpose of this article is to initiate the development of the scientific direction of medical geology, as well as the relationship between medicine and geology and the problems that can be considered and solved.
The capital of Bulgaria, Sofia is a growing city with population around 1.22 million. The city is exposed to a high seismic risk since it is placed in the centre of Sofia seismic area. Over the centuries in the town of Sofia the macroseismic intensities have been larger than IX (MSK). A study of the site effects and the microzonation of a part of metropolitan Sofia, based on a modelling of seismic ground motion along three cross sections are presented. Realistic synthetic strong motion waveforms have been computed for an expected scenario earthquake (M = 7) applying a hybrid modelling method, based on the modal summation technique and finite differences scheme. The site amplification is determined in terms of response spectra ratio (RSR). A set of time histories and quantities of earthquake engineering interest are supplied, that allow the definition of six zones characterized by specific response spectra.
Preliminary descriptions are given of selected specimens from an assemblage of >65 isolated vertebrate remains, collected in 1985 at the Labirinta cave situated between the villages of Drashan and Breste, east of Cherven Briag (Vratsa district, northwest Bulgaria), from strata of late Maastrichtian age (Kajl?ka Formation). Recorded are a fragmentary lower jaw of a mosasaurine squamate, Mosasaurus cf. hoffmanni (MANTELL, 1829), with two teeth preserved in situ, as well as two isolated teeth of lamniform sharks, assigned to Squalicorax pristodontus (AGASSIZ, 1843) and Anomotodon sp. Other vertebrate remains in this assemblage include rather poorly preserved fragments of skull and appendicular skeleton of mosasaurs, but it cannot be ruled out that other vertebrate groups (elasmosaurid plesiosaurs) are represented as well. To establish this, the additional material needs to be studied in detail and compared with existing collections; it will be described in full at a later date. A partial phragmocone of a scaphitid ammonite, found associated, is here assigned to Hoploscaphites constrictus (J. SOWERBY, 1817) and briefly described as well. This record dates the Labirinta cave sequence as Maastrichtian, as does the echinoid Hemipneustes striatoradiatus (LESKE 1778); tooth morphology of Squalicorax pristodontus and a find of the pachydiscid ammonite Anapachydiscus (Menuites) cf. terminus WARD and KENNEDY 1993 from correlative strata nearby narrow this down to late, or even latest Maastrichtian. Finally, some remarks on mosasaur and plesiosaur distribution during the Campanian-Maastrichtian across Europe are added.
