Трифторацетат кальция: новый структурный тип

Objectives. The study was devoted to considering the features of the synthesis and crystal structure of calcium trifluoroacetate Ca2(CF3COO)4·8CF3COOH and investigating the products of its thermal behavior.Methods. The compositions of the proposed structural form were characterized by various physicochemical methods (X-ray diffraction, IR spectroscopy), and the products of thermal decomposition were determined under dynamic vacuum conditions.Results. The reaction between calcium carbonate and 99% trifluoroacetic acid yielded a new structural type of calcium trifluoroacetate Ca2(CF3COO)4·8CF3COOH (I) in the form of colorless prismatic crystals unstable air. X-ray diffraction results confirmed the composition I: space group P21, with unit cell parameters: a = 10.0193(5) Å, b = 15.2612(7) Å, c = 16.3342(8) Å, β = 106.106(2)°, V = 2399.6(2) Å3, Z = 2. The structure is molecular, constructed from Ca2(CF3COO)4·8CF3COOH dimers. The end molecules of the trifluoroacetic acid were involved in the formation of intramolecular hydrogen bonds with oxygen atoms of the bidentate bridging anions CF3COO−. There were strongly pronouncedsymmetric and asymmetric absorption bands of COO and CF3-groups in the IR spectrum of the resulting compound in the range of 1200–1800 cm−1. The definite peak of the oscillation of the OH-group at 3683 cm−1 corresponds to the trifluoroacetic acid molecules present in the structure. The broadpeak of the valence oscillations in the range of 3300–3500 cm−1 is caused by the presence of intramolecular hydrogen bonds. Decomposition began at 250°C and 10−2 mm Hg with calcium fluoride CaF2 as the final decomposition product.Conclusions. We obtained a previously undescribed calcium–trifluoroacetic acid complex whose composition can be represented by Ca2(CF3COO)4·8CF3COOH. The crystal island structure is a dimeric molecule where the calcium atoms are bound into dimers by four trifluoroacetate groups. The complex was deposited in the Cambridge Structural Data Bank with a deposit number CCDC 2081186. Although the compound has a molecular structure, thermal decomposition leads to the formation of calcium fluoride characterized by a small particle size, which may further determine its applications.Цели. Работа посвящена рассмотрению особенностей синтеза и кристаллического строения трифторацетата кальция Ca2(CF3COO)4·8CF3COOH, а также изучению продуктов его термического поведения.Методы. Соединение охарактеризовано различными физико-химическими методами (рентгеноструктурный анализ, ИК-спектроскопия), установлены продукты термического разложения в условиях динамического вакуума.Результаты. Взаимодействием карбоната кальция с 99% трифторуксусной кислотой синтезирован новый структурный тип трифторацетата кальция Ca2(CF3COO)4·8CF3COOH (I) в виде неустойчивых на воздухе бесцветных призматических кристаллов. Строение I установлено по результатам рентгеноструктурного анализа: пространственная группа Р21, параметры элементарной ячейки: a = 10.0193(5) Å, b = 15.2612(7) Å, c = 16.3342(8) Å, β = 106.106(2)°, V = 2399.6(2) Å3, Z = 2. Структура молекулярная, построена из димеров Ca2(CF3COO)4·8CF3COOH. Торцевые молекулы трифторуксусной кислоты участвуют в образовании внутримолекулярных водородных связей с атомами кислорода бидентатных мостиковых анионов CF3COO−. На ИК-спектре полученного соединения в диапазоне 1200–1800 см−1 присутствуют ярко выраженные симметричные и асимметричные полосы поглощения СОО и CF3-групп. Четкий пик колебания OH-группы на 3683 см−1 соответствует присутствующим в структуре молекулам трифторуксусной кислоты. Широкий пик валентных колебаний в области 3300–3500 см−1 обусловлен наличием внутримолекулярных водородных связей. При давлении 10−2 мм рт.ст. разложение начинается при 250 °С, конечным продуктом разложения является фторид кальция CaF2.Выводы. Нами получен ранее не описанный комплекс кальция с трифторуксусной кислотой, состав которого может быть представлен формулой Ca2(CF3COO)4·8CF3COOH, кристаллическая островная структура которого представляет собой димерную молекулу, а атомы кальция связаны в димеры четырьмя трифторацетатными группами. Комплекс задепонирован в Кембриджском банке структурных данных, номер депонирования – CCDC 2081186. Соединение имеет молекулярное строение, термическое разложение приводит к образованию фторида кальция, характеризующегося небольшим размером частиц, что может в дальнейшем обусловить его применение

Carbon deficiencies in the primaries of some classical Algols

The equivalent widths of C II $\lambda$ 4267 \AA line were measured for the mass-gaining primary stars of the 18 Algol-type binary systems. The comparison of the EWs of the gainers with those of the single standard stars having the same effective temperature and luminosity class clearly indicates that they are systematically smaller than those of the standard stars. The primary components of the classical Algols, located in the main-sequence band of the HR diagram, appear to be C poor stars. We estimate $[N_{C} /N_{tot}]$ relative to the Sun as -1.91 for GT Cep, -1.88 for AU Mon and -1.41 for TU Mon, indicating poorer C abundance. An average differential carbon abundance has been estimated to be -0.82 dex relative to the Sun and -0.54 dex relative to the main-sequence standard stars. This result is taken to be an indication of the transferring material from the evolved less-massive secondary components to the gainers such that the CNO cycle processed material changed the original abundance of the gainers. There appear to be relationships between the EWs of C II $\lambda$ 4267 \AA line and the rates orbital period increase and mass transfer in some Algols. As the mass transfer rate increases the EW of the C II line decreases, which indicates that accreted material has not been completely mixed yet in the surface layers of the gainers. This result supports the idea of mixing as an efficient process to remove the abundance anomaly built up by accretion. Chemical evolution of the classical Algol-type systems may lead to constrains on the initial masses of the less massive, evolved, mass-losing stars.Comment: 10 pages, 4 figures, accepted in MNRA

CoRoT photometry and high-resolution spectroscopy of the interacting eclipsing binary AU Mon

Analyses of very accurate CoRoT space photometry, past Johnson V photoelectric photometry and high-resolution \'echelle spectra led to the determination of improved and consistent fundamental stellar properties of both components of AU Mon. We derived new, accurate ephemerides for both the orbital motion (with a period of 11.113d) and the long-term, overall brightness variation (with a period of 416.9d) of this strongly interacting Be + G semi-detached binary. It is shown that this long-term variation must be due to attenuation of the total light by some variable circumbinary material. We derived the binary mass ratio $M_{\rm G}/M_{\rm B}$ = 0.17\p0.03 based on the assumption that the G-type secondary fills its Roche lobe and rotates synchronously. Using this value of the mass ratio as well as the radial velocities of the G-star, we obtained a consistent light curve model and improved estimates of the stellar masses, radii, luminosities and effective temperatures. We demonstrate that the observed lines of the B-type primary may not be of photospheric origin. We also discover rapid and periodic light changes visible in the high-quality residual CoRoT light curves. AU Mon is put into perspective by a comparison with known binaries exhibiting long-term cyclic light changes.Comment: Accepted for publication in MNRA

Мониторинг паразитарных болезней продуктивных животных на территории Самарской области

The purpose of the research: to monitor the epizootic situation on parasitic diseases in productive animals in the Samara region using a database. materials and methods. Research was performed at the Department of invasive diseases of Samara Research Veterinary Station Samara RVS FSBSI. Fecal samples from productive animals were examined by Fuelleborn’s method using polymerase chain reaction to visualize species-specific DNA sequences, and an immune chromatographic method in detecting of antigens Dirofilaria immitis in serum, plasma and whole blood of dogs and oocysts Giardia duodenalis in dogs’ feces. The extensity of invasion was estimated with regard to the number of analyses of biomaterial from animals whose owners consulted veterinary physicians. For the monitoring, we used the database “Parasitic diseases in productive animals and small domestic animals in the Samara region” developed in Samara RVS in 2013 which enables to monitor the health status of the animal during its lifetime as well as epizootic situation on parasitic diseases in single localities, economies, districts and in Samara region in general. Results and discussion. Research results revealed that Strongylata had been registered in 17 districts at extensity of invasion from 5 to 70%, Strongyloides, Moniezia, Trichocephala - in 10 districts (EI 10-80%), Skrjabinema - in 7 districts ( EI 5-10%), Nematodirus - in 5 districts (EI 20-80%), Parascaris, Ascaris, Paramphistomum - in 3 districts (EI 5-40%), Fasciola, Coccidia, Dictyocaulus - in 2 districts (EI 5-15%). The biggest species diversity of helminths (7 species) were found in Bolsheglushitsky, Kinelsky and Borsky districts of the Samara region. The monitoring showed the decrease in worm species diversity in 2016 in all districts of Samara region compared to 2015. Parasitic protozoans, Eimeria, were found in all districts of the Samara region. A significant reduction of worm species diversity was associated with permanent planned treatment of productive animals with anthelmintics. The results obtained were used in a number of livestock farms of the Samara region to control the epizootic situation as well as for treatment and prevention of diseases in productive animals.Цель исследований: провести мониторинг эпизоотической ситуации паразитарных болезней продуктивных животных в районах Самарской области с использованием базы данных. Материалы и методы. Научные исследования проводили на базе отдела инвазионных болезней Самарской научно-исследовательской ветеринарной станции. Пробы фекалий от продуктивных животных исследовали по методу Фюллеборна, полимеразной цепной реакцией для выделения видоспецифических последовательностей ДНК и иммунохроматографического метода путем выявления антигенов Dirofilaria immitis в сыворотке, плазме и цельной крови собак и ооцист Giardia duodenalis в фекалиях собак. Экстенсивность инвазии рассчитывали по отношению к числу проведенных анализов биоматериала от животных, владельцы которых обращались за ветеринарной помощью. Для мониторинга использовали разработанную в Самарской НИВС базу данных «Паразитарные заболевания продуктивных и мелких домашних животных в Самарской области», которая позволяет отслеживать состояние здоровья животного в течение его жизни, а также эпизоотическую ситуацию по паразитозам в отдельных населенных пунктах, хозяйствах, районах и по Самарской области в целом. Результаты и обсуждение. В результате проведенных исследований было установлено, что стронгилята были зарегистрированы в 17 районах при экстенсивности инвазии от 5 до 70%, стронгилоиды, мониезии, трихоцефалы - в 10 районах (10-80%), скрябинема - в 7 районах (5-10%), нематодиры - в 5 районах (20-80%), параскариды, аскариды, парамфистомы - в 3 районах (5-40%), фасциолы, кокцидии, диктиокаулы - в 2 районах (5-15%). Наибольшее видовое разнообразие гельминтов (7 видов) отмечено в Большеглушицком, Кинельском, Борском районах области. Мониторинг показал, что число видов гельминтов в 2016 г. по сравнению с 2015 г. снизилось во всех районах области. Простейших рода Eimeria выявляли во всех районах области. Значительное снижение видового состава гельминтов связано с планомерным проведением плановых обработок продуктивных животных антигельминтными препаратами. Полученные результаты были использованы в ряде животноводческих хозяйств Самарской области для контроля эпизоотологической ситуации, а также лечения и профилактики болезней продуктивных животных

Identification of novel Coxiella burnetii genotypes from Ethiopian ticks

Background: Coxiella burnetii , the etiologic agent of Q fever, is a highly infectious zoonotic bacterium. Genetic information about the strains of this worldwide distributed agent circulating on the African continent is limited. The aim of the present study was the genetic characterization of C. burnetii DNA samples detected in ticks collected from Ethiopian cattle and their comparison with other genotypes found previously in other parts of the world. Methodology/Principal Findings: A total of 296 tick samples were screened by real-time PCR targeting the IS 1111 region of C. burnetii genome and from the 32 positive samples, 8 cases with sufficient C. burnetii DNA load ( Amblyomma cohaerens ,n 5 6; A. variegatum ,n 5 2) were characterized by multispacer sequence typing (MST) and multiple-locus variable-number tandem repeat analysis (MLVA). One novel sequence type (ST), the proposed ST52, was identified by MST. The MLVA-6 discriminated the proposed ST52 into two newly identified MLVA genotypes: type 24 or AH was detected in both Amblyomma species while type 26 or AI was found only in A. cohaerens . Conclusions/Significance: Both the MST and MLVA genotypes of the present work are closely related to previously described genotypes found primarily in cattle samples from different parts of the globe. This finding is congruent with the source hosts of the analyzed Ethiopian ticks, as these were also collected from cattle. The present study provides genotype information of C. burnetii from this seldom studied East-African region as well as further evidence for the presumed host-specific adaptation of this agent

A Novel Obligate Intracellular Gamma-Proteobacterium Associated with Ixodid Ticks, Diplorickettsia massiliensis, Gen. Nov., Sp. Nov

Background: Obligate intracellular bacteria of arthropods often exhibit a significant role in either human health or arthropod ecology. Methodology/Principal Findings: An obligate intracellular gamma-proteobacterium was isolated from the actively questing hard tick Ixodes ricinus using mammalian and amphibian cell lines. Transmission electron microscopy revealed a unique morphology of the bacterium, including intravacuolar localization of bacteria grouped predominantly in pairs and internal structures composed of electron-dense crystal-like structures and regular multilayer sheath-like structures. The isolate 20B was characterized to determine its taxonomic position using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that this strain belongs to the family Coxiellaceae, order Legionellales of Gamma-proteobacteria, and the closest relatives are different Rickettsiella spp. The level of 16S rRNA gene sequence similarity between strain 20B and other recognized species of the family was below 94.5%. Partial sequences of the rpoB, parC and ftsY genes confirmed the phylogenetic position of the new isolate. The G+C content estimated on the basis of whole genome analysis of strain 20B was 37.88%. On the basis of its phenotypic and genotypic properties, together with phylogenetic distinctiveness, we propose that strain 20B to be classified in the new genus Diplorickettsia as the type strain of a novel species named Diplorickettsia massiliensis sp. nov. Conclusions/Significance: Considering the source of its isolation (hard tick, often biting humans) the role of this bacterium in the pathology of humans, animals and ticks should be further investigated

Coxiella burnetii, the Agent of Q Fever, Replicates within Trophoblasts and Induces a Unique Transcriptional Response

Q fever is a zoonosis caused by Coxiella burnetii, an obligate intracellular bacterium typically found in myeloid cells. The infection is a source of severe obstetrical complications in humans and cattle and can undergo chronic evolution in a minority of pregnant women. Because C. burnetii is found in the placentas of aborted fetuses, we investigated the possibility that it could infect trophoblasts. Here, we show that C. burnetii infected and replicated in BeWo trophoblasts within phagolysosomes. Using pangenomic microarrays, we found that C. burnetii induced a specific transcriptomic program. This program was associated with the modulation of inflammatory responses that were shared with inflammatory agonists, such as TNF, and more specific responses involving genes related to pregnancy development, including EGR-1 and NDGR1. In addition, C. burnetii stimulated gene networks organized around the IL-6 and IL-13 pathways, which both modulate STAT3. Taken together, these results revealed that trophoblasts represent a protective niche for C. burnetii. The activation program induced by C. burnetii in trophoblasts may allow bacterial replication but seems unable to interfere with the development of normal pregnancy. Such pathophysiologocal processes should require the activation of immune placental cells associated with trophoblasts

Coxiella burnetii in Humans and Ticks in Rural Senegal

Q fever is a zoonotic disease known since 1937. The disease may be severe, causing pneumonia, hepatitis and endocarditis. Q fever agent has been described as a possible biological weapon. Animals—especially domestic cows, goats and sheep—are considered reservoirs for this infection. They are capable of sustaining the infection for long periods and excreting viable bacteria, infecting other animals and, occasionally, humans. Here we studied the distribution of Q fever in a poorly studied region, Senegal. We studied the agent of Q fever both in ticks parasitizing domestic animals and in humans (antibodies in serum, bacteria in feces, saliva and milk). We found from the studied regions the bacterium is highly prevalent in rural Senegal. Up to 37.6% of five different and most prevalent tick species may carry the bacterium. Humans living in such areas, as other mammals, may occasionally excrete Q fever agent through feces and milk

Multispacer Sequence Typing for Mycobacterium tuberculosis Genotyping

Background: Genotyping methods developed to survey the transmission dynamics of Mycobacterium tuberculosis currently rely on the interpretation of restriction and amplification profiles. Multispacer sequence typing (MST) genotyping is based on the sequencing of several intergenic regions selected after complete genome sequence analysis. It has been applied to various pathogens, but not to M. tuberculosis. Methods and Findings: In M. tuberculosis, the MST approach yielded eight variable intergenic spacers which included four previously described variable number tandem repeat loci, one single nucleotide polymorphism locus and three newly evaluated spacers. Spacer sequence stability was evaluated by serial subculture. The eight spacers were sequenced in a collection of 101 M. tuberculosis strains from five phylogeographical lineages, and yielded 29 genetic events including 13 tandem repeat number variations (44.82%), 11 single nucleotide mutations (37.93%) and 5 deletions (17.24%). These 29 genetic events yielded 32 spacer alleles or spacer-types (ST) with an index of discrimination of 0.95. The distribution of M. tuberculosis isolates into ST profiles correlated with their assignment into phylogeographical lineages. Blind comparison of a further 93 M. tuberculosis strains by MST and restriction fragment length polymorphism-IS6110 fingerprinting and mycobacterial interspersed repetitive units typing, yielded an index of discrimination of 0.961 and 0.992, respectively. MST yielded 41 different profiles delineating 16 related groups and proved to be more discriminatory than IS6110-based typing for isolates containing M<8 IS6110 copies (P<0.0003). MST was successfully applied to 7/10 clinical specimens exhibiting a Cts <= 42 cycles in internal transcribed spacer-real time PCR. Conclusions: These results support MST as an alternative, sequencing-based method for genotyping low IS6110 copy-number M. tuberculosis strains. The M. tuberculosis MST database is freely available (http://ifr48.timone.univ-mrs.fr/MST_MTuberculosis/mst)