Phase separation in iron chalcogenide superconductor Rb0.8+xFe1.6+ySe2 as seen by Raman light scattering and band structure calculations

We report Raman light scattering in the phase separated superconducting single crystal Rb0.77Fe1.61Se2 with Tc = 32 K. The spectra have been measured in a wide temperature range 3K -500K. The observed phonon lines from the majority vacancy ordered Rb2Fe4Se5 (245) antiferromagnetic phase with TN= 525 K demonstrate modest anomalies in frequency, intensity and halfwidth at the superconductive phase transition. We identify phonon lines from the minority compressed Rb{\delta}Fe2Se2 (122) conductive phase. The superconducting gap with dx2-y2 symmetry is also detected in our spectra. In the range 0-600 cm-1 we observed the low intensive but highly polarized B1g-type background which becomes well structured under cooling. The possible magnetic or multiorbital origin of this background has been discussed. We argue that phase separation in M0.8+xFe1.6+ySe2 has pure magnetic origin. It occurs below Neel temperature when iron magnetic moment achieves some critical magnitude. We state that there is a spacer between the majority 245 and minority 122 phases. Using ab-initio spin polarized band structure calculations we demonstrate that compressed vacancy ordered Rb2Fe4Se5 phase can be conductive and therefore may serve as a protective interface spacer between the pure metallic Rb{\delta}Fe2Se2 phase and the insulating Rb2Fe4Se5 phase providing the percolative Josephson-junction like superconductivity in the whole sample of Rb0.8+xFe1.6+ySe2 Our lattice dynamics calculations show significant difference in the phonon spectra of the conductive and insulating Rb2Fe4.Se5 phases.Comment: This paper is devoted to the memory of academician Kirill Borisovich Tolpygo, prominent Physicist, Teacher and Citizen, who made a great contribution to the lattice dynamics theory and many other branches of solid state physic

An improvement of the Berry--Esseen inequality with applications to Poisson and mixed Poisson random sums

By a modification of the method that was applied in (Korolev and Shevtsova, 2009), here the inequalities $$\rho(F_n,\Phi)\le\frac{0.335789(\beta^3+0.425)}{\sqrt{n}}$$ and $$\rho(F_n,\Phi)\le \frac{0.3051(\beta^3+1)}{\sqrt{n}}$$ are proved for the uniform distance $\rho(F_n,\Phi)$ between the standard normal distribution function $\Phi$ and the distribution function $F_n$ of the normalized sum of an arbitrary number $n\ge1$ of independent identically distributed random variables with zero mean, unit variance and finite third absolute moment $\beta^3$. The first of these inequalities sharpens the best known version of the classical Berry--Esseen inequality since $0.335789(\beta^3+0.425)\le0.335789(1+0.425)\beta^3<0.4785\beta^3$ by virtue of the condition $\beta^3\ge1$, and 0.4785 is the best known upper estimate of the absolute constant in the classical Berry--Esseen inequality. The second inequality is applied to lowering the upper estimate of the absolute constant in the analog of the Berry--Esseen inequality for Poisson random sums to 0.3051 which is strictly less than the least possible value of the absolute constant in the classical Berry--Esseen inequality. As a corollary, the estimates of the rate of convergence in limit theorems for compound mixed Poisson distributions are refined.Comment: 33 page

Phase separation in iron chalcogenide superconductor Rb₀.₈₊xFe₁.₆₊ySe₂ as seen by Raman light scattering and band structure calculations

We report Raman light scattering in the phase separated superconducting single crystal Rb₀.₇₇Fe₁.₆₁Se₂ with Tc = 32 K over a wide temperature region 3–500 K. The observed phonon lines from the majority vacancy ordered Rb₂Fe₄Se₅ (245) antiferromagnetic phase with TN = 525 K demonstrate modest anomalies in the frequency, intensity and halfwidth at the superconductive phase transition. We identify phonon lines from the minority compressed RbδFe₂Se₂ (122) conductive phase. The superconducting gap with dx₂₋y₂ symmetry has been detected in our spectra. In the range 0–600 cm–¹ we observe a weak but highly polarized B₁g-type backgroundwhich becomes well-structured upon cooling. A possible magnetic or multiorbital origin of this background is discussed. We argue that the phase separation in M₀.₈₊xFe₁.₆₊ySe₂ is of pure magnetic origin. It occurs below the Néel temperature when the magnetic moment of iron reaches a critical value. We state that there is a spacer between the majority 245 and minority 122 phases. Using ab initio spin-polarized band structure calculations we demonstrate that the compressed vacancy ordered Rb₂Fe₄Se₅ phase can be conductive and therefore may serve as a protective interface spacer between the purely metallic RbδFe₂Se₂ phase and the insulating Rb₂Fe₄Se₅ phase providing percolative Josephson-junction like superconductivity all throughout of Rb₀.₈₊xFe₁.₆₊ySe₂. Our lattice dynamics calculations show significant differences in the phonon spectra of the conductive and insulating Rb₂Fe₄Se₅ phases

Aggregation of αSynuclein promotes progressive in vivo neurotoxicity in adult rat dopaminergic neurons

Fibrillar αSynuclein is the major constituent of Lewy bodies and Lewy neurites, the protein deposits characteristic for Parkinson’s disease (PD). Multiplications of the αSynuclein gene, as well as point mutations cause familial PD. However, the exact role of αSynuclein in neurodegeneration remains uncertain. Recent research in invertebrates has suggested that oligomeric rather than fibrillizing αSynuclein mediates neurotoxicity. To investigate the impact of αSynuclein aggregation on the progression of neurodegeneration, we expressed variants with different fibrillation propensities in the rat substantia nigra (SN) by means of recombinant adeno-associated viral (AAV) vectors. The formation of proteinase K-resistant αSynuclein aggregates was correlated to the loss of nigral dopaminergic (DA) neurons and striatal fibers. Expression of two prefibrillar, structure-based design mutants of αSynuclein (i.e., A56P and A30P/A56P/A76P) resulted in less aggregate formation in nigral DA neurons as compared to human wild-type (WT) or the inherited A30P mutation. However, only the αSynuclein variants capable of forming fibrils (WT/A30P), but not the oligomeric αSynuclein species induced a sustained progressive loss of adult nigral DA neurons. These results demonstrate that divergent modes of αSynuclein neurotoxicity exist in invertebrate and mammalian DA neurons in vivo and suggest that fibrillation of αSynuclein promotes the progressive degeneration of nigral DA neurons as found in PD patients

Epizootic pertussis focus of hamadryad baboons

The absence of an adequate experimental animal model makes difficult study of immunity against whooping cough and its pathogenesis. Experimental whooping cough reported by us earlier in pubescent non-human primates of the Old World was accompanied by specific clinical and laboratory marks in the absence of cough. The possibility of pertussis modelling while experimental whooping cough in impuberal hamadryad baboons was investigated. In the process of selection of monkeys for the further studies for perfecting of experimental model for pertussis research unexpectedly were detected specific pertussis antibodies in impuberal hamadryad baboons.The aim of the study: revealing of source of infection and transmission of pertussis to hamadryad baboons and investigation of response of antibody-positive impuberal hamadryad baboons to secondary contagion by B. pertussis bacteria while experimental infection.Results. 18 veterinary checked, somatically healthy hamadryad baboons of various gender managed in two neighboring cages. Specific pertussis IgM and IgG antibodies were found in blood serum of all the animals and one of the monkey keepers. By real-time PCR in nasopharyngeal swabs of the monkey keeper and three 7- and 9-month-old hamadryad baboons were registered single B. pertussis genom equivalents. Seropositive impuberal hamadryad baboons were experimentally challenged by virulent B. pertussis 475 strain. Quantity of B. pertussis genom equivalents and percentage of IgM and IgG antibodies in impuberal hamadryad baboons after experimental infection were detected. These results were comparable with such received after secondary experimental challenge of monkeys by B. pertussis. Humoral immuneresponse was characterized by booster effect and rapid B. pertussis elimination.Conclusion. The case of transmission of B.pertussis bacteria to hamadryad baboons by natural contagion and epizootic focus of pertussis in apery conditions were registered. In dynamics of immune response and level of bacterial load in experimentally infected impuberal and pubescent hamadryad baboons were not revealed significant differences. The possibility of asymptomatic B.pertussis transmission from man to monkey and from monkey to man without definitive spasmodic cough was reviewed. Pertussis research perspectives using experimental model of non-human primates of the Old World were marked

Reparative processes in liver after laser exposure of bone marrow localization zones

We investigated the features of reparative process in the resected liver after laser irradiation of the zones of red bone marrow localization In rat experiment, the wedge-shaped resection of a liver lobe was performed. Infrared laser was applied for 5 days after the operation. The hystological analysis of liver specimens demonstrated the increase in hepatocyte proliferation with the increase in the ki-67 index and the nuclear-cytoplasmic ratio, the increase in binuclear hepatocytes number, the increase in the expression level of VEGF and Hsp 70 in the laser treatment group that is the evidence of successful recovery process and neoangiogenesis. The activation of hepatic tissue regeneration after laser irradiation of bone marrow localization zones may be the basis for the development of methods for treatment of liver disease patients.Исследованы особенности репаративных процессов в резецированной печени после лазерного воздействия на зоны локализации красного костного мозга. В эксперименте на крысах моделировали клиновидную резекцию доли печени. Лазерное воздействие осуществляли инфракрасным лазером в течение 5 суток после операции. После морфометрического анализа препаратов печени отмечено усиление пролиферации гепатоцитов с повышением индекса кi-67 и ядерно-цитоплазматического отношения, увеличение содержания двуядерных гепатоцитов, повышение уровня экспрессии VEGF и Hsp 70, что является свидетельством успешно протекающих восстановительных процессов и неоангиогенеза. Полученные данные об активации регенерации печеночной ткани после лазерного воздействия на зоны локализации костного мозга могут являться основой для разработки методов лечения пациентов с заболеваниями печени

Identification of the Farm Animals Immune to Pathogens of Zoonotic Infectious Diseases in the Republic of Guinea

The most common anthropozoonoses on the African continent are coxiellosis and Rift Valley fever. It is known that detection of specific IgG antibodies in the blood sera of farm animals is one of the indicators of the pathogen circulation in a certain territory. The aim of the work was to identify specific IgG antibodies in the blood sera of farm animals collected on the territory of the Republic of Guinea to pathogens of zoonotic infectious diseases: coxiellosis, brucellosis, glanders, CCHF, West Nile and Rift Valley fevers, using enzyme immunoassay (ELISA). Materials and methods. A panel of 970 samples of blood sera from farm animals inhabiting all landscape-geographical zones of Guinea was compiled for the work. Identification of specific antibodies was carried out using enzyme immunoassay with preparations recommended for veterinary studies. Results and discussion. Specific antibodies to zoonoses were detected in 700 out of 1074 samples (65.2 % of the total), including: to Coxiella burnetii – in 172 (16.0 %); to Brucella spp. – in 212 (19.7 %); viruses of Rift Valley fever – 85 (7.9 %); CCHF – in 139 (12.9 %) and West Nile fever – in 92 (8.6 %). Antibodies to Burkholderia mallei were not found in the tested material. Positive samples were registered in all landscape-geographical zones. Thus, an urgent task is to continue studying the circulation of pathogens of zoonoses and anthropozoonoses in the territory of the Republic of Guinea and to organize regular monitoring over the spread of zoonotic infectious diseases in collaboration with veterinary services, which will allow timely forecasting and coordinating prophylactic (anti-epidemic) measures to prevent cases of diseases

Approaches to Reduce Adverse Effect of Vaccinia Virus in Orally Immunized Mice

Objective of the investigation was to model the adverse action of vaccinia virus (VV), caused by oral immunization of mice and to evaluate efficacy of its reduction, using therapeutic and prophylactic drugs. Materials and methods. Virological and immunological research methods were used. Results and conclusions. Reproduced was pathological action of VV in the orally infected mice. The ability to reduce the side effect and protect mice from lethal infection was demonstrated by such preparations as Metisazon, Likopid, and NIOCH-14 orally administered in the investigated schemes. Moreover preliminary single oral immunization with TEOVak smallpox vaccine before oral infection with Neurovaccine-92 strain of VV also lowered pathogenic effect and protected mice against death. All the investigated schemes of drug administration did not affect the immune response if used alongside with TEOVak smallpox vaccine and can be deployed to develop safe schemes of primary oral vaccination against smallpox. In addition, such drugs as Ribomunil, Immudon, Ingavirin can be used as means to enhance the immune response to smallpox vaccines

Эпизоотический очаг коклюша у обезьян вида Papio gamadryas

The absence of an adequate experimental animal model makes difficult study of immunity against whooping cough and its pathogenesis. Experimental whooping cough reported by us earlier in pubescent non-human primates of the Old World was accompanied by specific clinical and laboratory marks in the absence of cough. The possibility of pertussis modelling while experimental whooping cough in impuberal hamadryad baboons was investigated. In the process of selection of monkeys for the further studies for perfecting of experimental model for pertussis research unexpectedly were detected specific pertussis antibodies in impuberal hamadryad baboons.The aim of the study: revealing of source of infection and transmission of pertussis to hamadryad baboons and investigation of response of antibody-positive impuberal hamadryad baboons to secondary contagion by B. pertussis bacteria while experimental infection.Results. 18 veterinary checked, somatically healthy hamadryad baboons of various gender managed in two neighboring cages. Specific pertussis IgM and IgG antibodies were found in blood serum of all the animals and one of the monkey keepers. By real-time PCR in nasopharyngeal swabs of the monkey keeper and three 7- and 9-month-old hamadryad baboons were registered single B. pertussis genom equivalents. Seropositive impuberal hamadryad baboons were experimentally challenged by virulent B. pertussis 475 strain. Quantity of B. pertussis genom equivalents and percentage of IgM and IgG antibodies in impuberal hamadryad baboons after experimental infection were detected. These results were comparable with such received after secondary experimental challenge of monkeys by B. pertussis. Humoral immuneresponse was characterized by booster effect and rapid B. pertussis elimination.Conclusion. The case of transmission of B.pertussis bacteria to hamadryad baboons by natural contagion and epizootic focus of pertussis in apery conditions were registered. In dynamics of immune response and level of bacterial load in experimentally infected impuberal and pubescent hamadryad baboons were not revealed significant differences. The possibility of asymptomatic B.pertussis transmission from man to monkey and from monkey to man without definitive spasmodic cough was reviewed. Pertussis research perspectives using experimental model of non-human primates of the Old World were marked.Введение. Изучение патогенеза и иммунитета при коклюше затруднено в связи с отсутствием адекватной экспериментальной модели. Описанный нами ранее экспериментальный коклюш у половозрелых обезьян Старого Света сопровождался развитием характерных клинико-лабораторных признаков коклюша при отсутствии кашля. В процессе отбора обезьян для дальнейшей работы по совершенствованию экспериментальной модели для изучения коклюша у неполовозрелых павианов гамадрилов неожиданно были обнаруженыспецифические противококлюшные антитела.Цель. Выявление источника бактерий В. рertussis и пути их передачи павианам гамадрилам, а также изучение реакции организма серопозитивных неполовозрелых павианов на вторичный контакт с возбудителем коклюша при экспериментальном заражении. Результаты. 18 обследованных павианов гамадрилов разного пола, размещённые в двух соседних вольерных клетках, находились в состоянии соматического здоровья. В сыворотке крови всех животных и одного из сотрудников по уходу за животными были выявлены специфические антитела класса IgG и IgМ к возбудителю коклюша. Методом ПЦР в режиме реального времени из материала назофарингеальных мазков зарегистрированы единичные геном-эквиваленты B. pertussis у рабочего по уходу за животными и трёх павианов гамадрилов в возрасте 7–9 месяцев. Серопозитивные неполовозрелые павианы гамадрилы были экспериментально заражены вирулентными бактериями B. pertussis 475. Результаты определения количества геном-эквивалентов B. pertussis и относительного количества специфических IgG и IgМ у неполовозрелых павианов гамадрилов после экспериментального заражения были сопоставимы с таковыми у взрослых, дважды инфицированных обезьян. Гуморальный иммунный ответ характеризовался бустерным эффектом с быстрой элиминацией возбудителя. Заключение. Зарегистрирован случай передачи бактерий B. pertussis павианам гамадрилам естественным путем и эпизоотический очаг коклюша в условиях питомника. Не выявлено значимых различий в динамике развития иммунного ответа и бактериальной нагрузки у экспериментально инфицированных неполовозрелых и половозрелых павианов гамадрилов. Показана возможность передачи бактерий B. pertussis без характерного коклюшного кашля от человека к обезьяне и от обезьяны к обезьяне. Описаны перспективы изучения коклюша на экспериментальной модели обезьян Старого Света