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This paper reports the first description of the crystal structure and crystal chemical features of fluorcarletonite, a new mineral from the Murun potassium alkaline complex (Russia), obtained by means of single-crystal and powder X-ray diffraction (XRD), electron microprobe analysis (EMPA), thermogravimetry (TG), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. The crystal structure of fluorcarletonite, KNa4Ca4Si8O18(CO3)4(F,OH)⚫ H2O, a rare phyllosilicate mineral, contains infinite double-silicate layers composed of interconnected four- and eight-membered rings of SiO4 tetrahedra and connected through the interlayer K-, Na- and Ca-centered polyhedra and CO3 triangles. The X-ray diffraction analysis confirms the mineral to be tetragonal, P4∕mbm, a=13.219(1) Å, c=16.707(2) Å, V=2919.4(6) Å3 (powder XRD data), a=13.1808(5) Å, c=16.6980(8) Å, V=2901.0(3) Å3 (single-crystal XRD data, 100 K). The EMPA (average from 10 analyses) gave the following composition (wt %): SiO2 44.1(6), CaO 20.0(3), Na2O 11.1(3), K2O 4.5(2), F 1.3(5), TiO2 0.1(1) and Al2O3 0.03(3). The TG–DSC analysis confirmed the presence of H2O and CO2 (weight losses of 1.17 % and 14.9 %, respectively). The FTIR spectrum acquired in the range from 4000 to 400 cm−1 reveals the presence of H2O, CO3 and OH groups. The average formula of fluorcarletonite calculated from the results of EMPA and crystal structure refinement is K1.04Na3.89Ca3.87Ti0.01Si7.99Al0.01O18(CO3)3.86(F0.72OH0.28)⚫1.11H2O.

Enterobiasis is one of the most common human parasitic infections worldwide and in Bulgaria. The objective of this study was to ascertain the levels of intestinal secretory IgA antibodies in patients with enterobiasis, to determine the local immune response in this helminthiasis, and to evaluate its influence on clinical manifestations during infection. Faecal samples from 102 enterobiasis patients and 40 clinically healthy controls were examined. In individuals infected with Enterobius vermicularis , the range of values for SIgA was higher (from 27.5 μg/ml to 13916 μg/ml). However, no statistically significant difference was found between them and those in persons without evidence of infection (from 27.5 to 8999 μg/ml). In both groups of individuals (infected and non-infected), we observed differences in the levels of SIgA, which appeared to be dependent on the age and gender of the subjects. Significantly, higher values were observed in children and adolescents, as well as in males. In individuals with enterobiasis, a higher level of SIgA was observed in those with pronounced clinical symptoms (mean value = 2198.74) compared to asymptomatic individuals (mean value = 1588.54). The highest levels were observed in patients presenting with perianal pruritus (mean value = 3559.54). Our study of the local humoral immune response in people with enterobiasis is the first of its kind in the country. The results clearly show a direct correlation between the presence of clinical symptoms in enterobiasis and elevated levels of secretory IgA in faeces., Competing Interests: Conflicts of Interest The authors declare no conflicts of interest., (© 2024 E. Kaneva et al., published by Sciendo.)

Background: Pneumocystis pneumonia (PCP) commonly affects immunocompromised individuals, whereas in immunocompetent persons, it occurs relatively rarely, and in most cases, the Pneumocystis infection is detected as an asymptomatic colonization. The present study aimed to establish the prevalence of Pneumocystis jirovecii infection in human hosts with different immune status (immunocompromised and immunocompetent), using molecular diagnostic methods, and to compare their diagnostic value with that of classical staining methods., Methods: We used the collected-to-this-moment data from a prospective study on the prevalence of pneumocystosis among the Bulgarian population. Clinical specimens (including throat secretions, induced sputum, tracheal aspirates, and bronchoalveolar lavage) collected from 220 patients suspected of PCP (153 immunocompetent and 67 immunocompromised patients) were examined with microscopic staining methods and real-time PCR for detection of P. jirovecii. Results: DNA of the pathogen was detected in 38 (17%) specimens (32 immunocompromised patients and 6 immunocompetent subjects). From all 220 clinical samples examined by staining methods, only five (2%) P. jirovecii cysts were detected by the Gomori stain. All patients with PCP were treated with trimethoprim-sulfamethoxazole, but in ten of them (HIV-positive patients), the disease had a fatal outcome., Conclusions: This study is the first in Bulgaria including the main available laboratory methods for diagnosis of human pneumocystosis. Regarding the etiological diagnosis of PCP, in our study the sensitivity of real-time PCR was higher compared to the staining methods. The choice of a method for sample collection and examination has an important role in the efficiency of the laboratory diagnostics.

Synthesis in the radiation field is a promising direction for the development of materials transformation processes, especially those differing in melting temperature. It has been established that the synthesis of yttrium-aluminum ceramics from yttrium oxides and aluminum metals in the region of a powerful high-energy electron flux is realized in 1 s, without any manifestations that facilitate synthesis, with high productivity. It is assumed that the high rate and efficiency of synthesis are due to processes that are realized with the formation of radicals, short-lived defects formed during the decay of electronic excitations. This article presents descriptions of the energy-transferring processes of an electron stream with energies of 1.4, 2.0, and 2.5 MeV to the initial radiation (mixture) for the production of YAG:Ce ceramics. YAG:Ce (Y 3 Al 5 O 12 :Ce) ceramics samples in the field of electron flux of different energies and power densities were synthesized. The results of a study of the dependence of the morphology, crystal structure, and luminescence properties of the resulting ceramics on the synthesis modes, electron energy, and electron flux power are presented.

YAG:Ce ceramics by the direct action of an electron beam with 1.4 MeV energy were synthesized on a mixture of a stoichiometric composition of Y, Al, and Ce oxides without adding any substances to facilitate the process. The synthesis is realized in a time less than 1 s. The main structural phase of the obtained ceramics is YAG and YAP can be additional. The luminescence characteristics of the synthesized samples, the excitation, luminescence, decay time, and pulsed cathodoluminescence spectra, are similar to those known for YAG:Ce phosphors. The conversion efficiency of the excitation energy into the luminescence of the samples reaches 60-70% of those used for the manufacture of LED phosphors. The set of processes that determine the rate and efficiency of radiation synthesis differs from those occurring during thermal methods by the existence of a high degree of the initial compositions' ionization under the influence of a radiation flux and a high probability of the decay of electronic excitations into short-lived radiolysis products.

The thermal behavior of stellerite from the Savinskoye deposit (Transbaikalia, Russia), Ca 7.69 Na 0.25 K 0.06 (Si 56.24 Al 15.76 )O 144 ·53.39H 2 O, was investigated by in situ high-temperature X-ray powder diffraction (HTXRPD) and ex situ HT infrared (IR) spectroscopic analysis. Four different HTXRPD experimental procedures were used to study the thermal behavior of the powder samples: (1) RT-750 °C, (2) RT-220 °C -RT, (3) 200-350-RT °C, and (4) 350-700 °C. Electron probe microanalysis and single-crystal X-ray diffraction were preliminary used to determine the chemical composition and crystal structure of stellerite. The A → B phase transition (Fmmm → Amma) starts at ∼110 °C and is completed at about 140 °C (in situ HTXRPD) and 200 °C (ex situ HTIR) depending on the experimental conditions. It involves a cell volume decrease of 5.8% (Experiment 1). The thermal expansion of stellerite is more pronounced along the b and c axes, with αa: αb: αc (× 10 -5 ) = 2.50:-25.52:-6.84 at 100 °C, 0.44:-21.75:-25.64 at 150 °C after the completion of the phase transition, and 3.06:-1.86:-16.94 at 500 °C. The reverse B → A transition occurs at temperatures below 100 °C during slow cooling (Experiment 2), however, it does not occur upon rapid cooling (Experiment 3). The B → D phase transition above 300 °C is not observed (Experiment 4). The temperature barrier of phase transition in the ex situ HTIR spectroscopy experiment is shifted towards high temperatures. The heating above 200 °C leads to an increase of 3430 cm -1 and a decrease of 3600 and 3260 cm -1 bands, which correspond to the stretching vibration of H 2 O. The heating above 400 °C causes complete dehydration of the stellerite., (© 2022. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry.)

Background: Bulgaria, with a high endemicity for malaria in the past, was declared by the WHO as a malaria-free country in 1965. We intended to analyze the epidemiological and clinical implications of imported malaria cases in Bulgaria., Methods: This is a retrospective cross-sectional analysis of all recorded cases of imported malaria in Bulgaria over a 21-year period (2000-2020). Patients' clinical records and information gathered from the epidemiological survey of each recorded malaria case were reviewed., Results: A total of 232 cases of imported malaria were reported, 147 (63.4%) were Bulgarian citizens (BC) and 85 (36.6%) were foreign nationals (FN). Two thirds (66.4%) of cases were diagnosed from April to October. Most BCs had travelled for work (66.6%) to Africa (93.9%) and were infected with P. falciparum (83.3%), while most FNs were migrants (54.7%), exposed in Asia (63.5%) with P. vivax infection (62.4%). Clinical complications and a fatal outcome were noted in 14.7% (n = 34) and 3.5% (n = 8) of cases respectively. All complicated cases were in BNs with P. falciparum infection., Conclusions: Bulgaria experiences a steady import of malaria. Efforts to improve diagnosis, management and prevention of malaria, as well as maintenance of a high degree of epidemiological vigilance are needed., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Toxocarosis is a zoonotic disease caused by migration and subsequent localization of nematode larvae of Toxocara spp. in human organs and tissues, which is manifested with development of various non-specific clinical symptoms. Main diagnostic methods are serological and consists in proving the presence of anti-Toxocara IgG antibodies in patient's sera. In humans, anti-Toxocara IgG has been shown to persist in the serum for a long time and cannot be used to distinguish between past and recent infection. Aim of the present work is to investigate the diagnostic significance of the specific IgG avidity level, determined by an immuno enzyme test developed by us, and the presence of anti-Toxocara IgA for distinguishing between acute and chronic toxocarosis. The study included 130 patients with positive results in routine serological ELISA and Western blot tests and with clinical symptoms of visceral and ocular toxocarosis. The results revealed low IgG avidity (≤40%) in nine (7.3%) and presence of anti-Toxocara IgA antibodies in 36 (26.2%) of the subjects. Low avidity of IgG antibodies was found only in the first tests, and a presence of specific IgA for up to 9 months. The results of our study give us reason to believe that determination of the IgG avidity in toxocarosis is of greater diagnostic value than the presence of IgA to establish the stage of the disease., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: A robust estimate of the number of people with chronic hepatitis C virus (HCV) infection is essential for an appropriate public health response and for monitoring progress toward the WHO goal of eliminating viral hepatitis. Existing HCV prevalence studies in the European Union (EU)/European Economic Area (EEA) countries are heterogeneous and often of poor quality due to non-probability based sampling methods, small sample sizes and lack of standardization, leading to poor national representativeness. This project aimed to develop and pilot standardized protocols for undertaking nationally representative HCV prevalence surveys in the general adult population. Methods: From 2016 to 2019 a team from the Robert Koch-Institute contracted by the European Centre for Disease Prevention and Control synthesized evidence on existing HCV prevalence surveys and survey methodology and drafted a protocol. The methodological elements of the protocol were piloted and evaluated in Bulgaria, Finland and Italy, and lessons learnt from the pilots were integrated in the final protocol. An international multidisciplinary expert group was consulted regularly. Results: The protocol includes three alternative study approaches: a stand-alone survey; a "nested" survey within an existing health survey; and a retrospective testing survey approach. A decision algorithm advising which approach to use was developed. The protocol was piloted and finalized covering minimum and gold standards for all steps to be implemented from sampling, data protection and ethical issues, recruitment, specimen collection and laboratory testing options, staff training, data management and analysis and budget considerations. Through piloting, the survey approaches were effectively implemented to produce HCV prevalence estimates and the pilots highlighted the strengths and limitations of each approach and key lessons learnt were used to improve the protocol. Conclusions: An evidence-based protocol for undertaking HCV prevalence serosurveys in the general population reflecting the different needs, resources and epidemiological situations has been developed, effectively implemented and refined through piloting. This technical guidance supports EU/EEA countries in their efforts to estimate their national hepatitis C burden as part of monitoring progress toward the elimination targets., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Sperle, Nielsen, Bremer, Gassowski, Brummer-Korvenkontio, Bruni, Ciccaglione, Kaneva, Liitsola, Naneva, Perchemlieva, Spada, Toikkanen, Amato-Gauci, Duffell and Zimmermann.)

Elpidite belongs to a special group of microporous zirconosilicates, which are of great interest due to their capability to uptake various molecules and ions, e.g., some radioactive species, in their structural voids. The results of a combined electron probe microanalysis and single-crystal X-ray diffraction study of the crystals of elpidite from Burpala (Russia) and Khan-Bogdo (Mongolia) deposits are reported. Some differences in the chemical compositions are observed and substitution at several structural positions within the structure of the compounds are noted. Based on the obtained results, a detailed crystal-chemical characterization of the elpidites under study was carried out. Three different structure models of elpidite were simulated: Na 2 ZrSi 6 O 15 ·3H 2 O (related to the structure of Russian elpidite), partly Ca-replaced Na 1.5 Ca 0.25 ZrSi 6 O 15 ·2.75H 2 O (close to elpidite from Mongolia), and a hypothetical CaZrSi 6 O 15 ·2H 2 O. The vibration spectra of the models were obtained and compared with the experimental one, taken from the literature. The strong influence of water molecule vibrations on the shape of IR spectra of studied structural models of elpidite is discussed in the paper.

Agrellite, NaCa 2 Si 4 O 10 F, is a tubular silicate mineral which crystal structure is characterized by extended [Si 8 O 20 ] 8- tubes and has a two-dimensional channel system. The mineral is a representative of a complex silicate family which contains some structural voids but cannot be considered as microporous because of small channel widths. However, the channel system of such minerals is able to host single guest atoms, molecules or radicals which can affect their physical properties. Presently, the exact mechanism of such hosting is undetermined. However, such information could be quite useful for materials' application as zeolites as well as for a better understanding of their formation mechanisms. In this work we couple X-ray diffraction, infrared (IR) spectroscopy and ab initio calculations to identify structural features in agrellite from Malyy Murun massif (Russia) caused by incorporation of either H 2 O or OH - into the channel system. We construct structural models of water-containing NaCa 2 Si 4 O 10 F and identified H 2 O positions. The derivation of H 2 O sites is based on simulation of IR-spectra. Infrared spectroscopy in combination with the ab initio calculation has proven to be an effective tool for the identification of the structural positions of hydroxyl anions (OH - ) and neutral water groups (H 2 O) in minerals.

Objective: This study piloted a European technical protocol for conducting chronic hepatitis C prevalence surveys in the general population. The pilot study took place in the Bulgarian city of Stara Zagora in 2018, and results of setting up, conducting and evaluating the survey are presented., Results: A probability-based sample of the general adult population was drawn from the local population registry, stratified by age and sex. A sample size of 999 was calculated, and accounting for 50% non-response, 1998 registered invitation letters were sent. Venous blood samples and questionnaire data were collected by the Regional Health Inspectorate in Stara Zagora. Blood samples were tested for anti-HCV, and if reactive for RNA. 252 (21.6%) of the participants were included in the study. Mean age and sex distribution differed between the participants (55.9 years, 60.3% females) and the total sample (48.9 years, 53.4%). The weighted chronic HCV prevalence among participants was 0.9% [95% CI 0.2-4.2%]. The approach of only sending registered letters contributed to a low response rate, and more efforts are needed to reduce non-response, especially among men and younger age groups. Results of the evaluation were integrated in the final technical protocol.

Background: In Bulgaria, more than 20 autochthonous human parasitic infections have been described and some of them are widespread. Over 50 imported protozoan and helminthic infections represent diagnostic and therapeutic challenges and pose epidemiological risks due to the possibility of local transmission., Aims: To establish the distribution of autochthonous and imported parasitic diseases among the population of the country over a 2-year period (2013-2014) and to evaluate their significance in the public health system., Study Design: Cross sectional study., Methods: We used the annual reports by regional health inspectorates and data from the National Reference Laboratory at the National Centre of Infectious and Parasitic Diseases on all individuals infected with parasitic diseases in the country. Prevalence was calculated for parasitic diseases with few or absent clinical manifestations (oligosymptomatic or asymptomatic infections). Incidence per 100.000 was calculated for diseases with an overt clinical picture or those that required hospitalisation and specialised medical interventions (e.g. surgery)., Results: During the research period, parasitological studies were conducted on 1441.244 persons, and parasitic infections were diagnosed in 22.039 individuals. Distribution of various parasitic pathogens among the population displayed statistically significant differences in prevalence for some intestinal parasites (enterobiasis 0.81%, giardiasis 0.34% and blastocystosis 0.22%). For certain zoonotic diseases such as cystic echinococcosis (average incidence of 3.99 per 100.000) and trichinellosis (average incidence of 0.8 per 100.000), the incidence exceeds several times the annual incidence recorded in the European Union., Conclusion: Parasitic diseases still pose a substantial problem with social and medical impacts on the residents of our country. Improved efficiency regarding autochthonous and imported parasitic diseases is essential in providing the public health system the tools it needs to combat these diseases. Attention should be focused on the various imported vector-borne parasitic diseases (e.g. malaria and cutaneous leishmaniasis) for which the country is potentially endemic.

Data in the literature addressing the ability of Toxocara infection in humans to induce development of atopic disease are controversial. The aim of our study was to determine the seroprevalence of anti-Toxocara antibodies in three groups of people: subjects with allergic symptoms and presence of allergen-specific IgE, subjects with allergic symptoms and absence of allergen-specific IgE, and clinically healthy blood donors. Serum samples from all subjects were tested by ELISA and Western blot for presence of specific antibodies against Toxocara canis. The results of our study did not support the link between toxocariasis and allergic manifestations in atopic patients. Among subjects with allergic symptoms and absence of atopy was found seroprevalence of 2·2% in Western blot. Same index in patients with atopy was 0·8%, and in clinically healthy blood donors 4·0%. Our study gives us grounds to consider that it is appropriate persons with allergic reactions, without evidence of atopy to be tested for presence of anti-Toxocara antibodies in the course of their diagnostic evaluation. Data from clinically healthy persons suggest that there is a 'hidden' infection among the population, which is not clinically manifested., (© 2015 John Wiley & Sons Ltd.)