Tunable Single-Atomic Charges on a Cleaved Intercalated Transition Metal Dichalcogenide

Control of a single ionic charge state by altering the number of bound electrons has been considered as an ultimate testbed for atomic charge-induced interactions and manipulations, and such subject has been studied in artificially deposited objects on thin insulating layers. We demonstrate that an entire layer of controllable atomic charges on a periodic lattice can be obtained by cleaving metallic Co_1/3NbS₂, an intercalated transition metal dichalcogenide. We identified a metastable charge state of Co with a different valence and manipulated atomic charges to form a linear chain of the metastable charge state. Density functional theory investigation reveals that the charge state is stable due to a modified crystal field at the surface despite the coupling between NbS₂ and Co via a_1g orbitals. The idea can be generalized to other combinations of intercalants and base matrices, suggesting that they can be a new platform to explore single-atom-operational 2D electronics/spintronics.

Na9 Bi5 Os3 O24 : A Diamagnetic Oxide Featuring a Pronouncedly Jahn-Teller-Compressed Octahedral Coordination of Osmium(VI)

The Jahn-Teller (JT) theorem constitutes one of the most fundamental concepts in chemistry. In transition-element chemistry, the 3d4 and 3d9 configurations in octahedral complexes are particularly illustrative, where a distortion in local geometry is associated with a reduction of the electronic energy. However, there has been a lasting debate about the fact that the octahedra are found to exclusively elongate. In contrast, for Na9 Bi5 Os3 O24 , the octahedron around Os6+ (5d2 ) is heavily compressed, lifting the degeneracy of the t2g set of 5d orbitals such that in the sense of a JT compression a diamagnetic ground state results. This effect is not forced by structural constraints, the structure offers sufficient space for osmium to shift the apical oxygen atoms to a standard distance. The relevance of these findings is far reaching, since they provide new insights in the hierarchy of perturbations defining ground states of open shell electronic systems.

Structural transition in AuAgTe4 under pressure

Gold is inert and forms very few compounds. One of the most interesting of those is calaverite AuTe₂, which has incommensurate structure and which becomes superconducting when doped or under pressure. There exist a 'sibling' of AuTe₂, the mineral sylvanite AuAgTe₄, which properties are almost unknown. In sylvanite Au and Ag ions are ordered in stripes, and Te₆ octahedra around metals are distorted in such a way that Ag becomes linearly coordinated, what is typical for Ag¹⁺ , whereas Au is square coordinated-it is typical for d ⁸ configurations, i.e. one can assign to Au the valence 3+. Our theoretical study shows that at pressure [Formula: see text] GPa there should occur in it a structural transition such that above this critical pressure Te₆ octahedra around Au and Ag become regular and practically identical. Simultaneously Te-Te dimers, existing at P  =  0 GPa, disappear, and material from a bad metal becomes a usual metal with predominantly Te 5p  states at the Fermi energy. We expect that, similar to AuTe₂, AuAgTe₄ should become superconducting above [Formula: see text].

[Nerve Growth Factor in Patients With Arterial Hypertension: Neuropsychical, Hemodynamic, Metabolic Relationships]

AIM

To investigate the changes of serum nerve growth factor (NGF) level in patients with arterial hypertension (AH) and obesity in dependence on the degree of psycho-emotional stress and physical activity.

MATERIALS AND METHODS

We examined 76 male patients with stage I and II AH with mean age 46.75±0.56 years (36 patients with and 40 without obesity). Control group consisted of 26 individuals without AH, obesity, and cardiovascular diseases. All patients underwent ambulatory blood pressure (BP) monitoring. Serum concentrations of NGF β-subunit and cortisol were determined by enzyme linked immunosorbent assay. For assessment of levels of psycho-emotional stress, reactive and personal anxiety, and physical activity we used Psychological Stress Measure (PSM-25), the Spielberger-Khanin questionnaire, and brief International Physical Activity Questionnaire (IPAQ), respectively.

RESULTS

Level of NGF in patients with AH and obesity (0.94±0.28 ρg/ml) was higher than in non-obese patients with AH (0.21±0.06 ρg/ml; p=0.018) with highest figures in patients with insufficient physical activity and high level of psychoemotional stress. In all groups of patients there was unidirectional reverse correlation between serum NGF and cortisol levels. According to ambulatory BP monitoring, NGF level was inversely proportional to systolic and diastolic BP variability in patients with AH and obesity and in the control group. Reduced serum concentration of NGF was associated with increased levels of reactive and personal anxiety.

CONCLUSION

Obtained data suggests that NGF plays an important role in complex multifactorial interactions between neuropsychic, cardiovascular and metabolic processes.

Psychological Stress in Pathogenesis of Essential Hypertension

The article represents literature review and provides evidence for psychological stress to play essential role in the development of arterial hypertension. The pathogenesis of hypertension is complex with a significant diversity and variability of the mechanisms involved in individual patient. In this regard, the determination of specific pathogenic pathways underlying sustained blood pressure elevation in each patient would substantially individualize therapeutic approaches, and hence increase the effectiveness of treatment. Psychological stress is proposed as a significant factor contributing to the development of hypertension. Global urbanization, sedentary lifestyle, daily stress at workplace, lack of physical activity and social support lead to increased anxiety, uncertainty, and finally to chronic mental and emotional stress. This review provides information about alterations in neuroendocrine and immune systems as the main pathogenic pathways linking psychological stress and hypertension. Endothelial dysfunction is considered not only as a consequence but also a primary factor causing prohypertensive state. Moreover, physical inactivity is discussed as one of the plausible mechanisms playing a key role in the development of hypertension in modern lifestyle conditions. Particularly the loss of connection between psychosocial strain and physical activity may underlie the deleterious effect of stress on cardiovascular and metabolic health.

Spin-singlet Quantum Ground State in Zigzag Spin Ladder Cu(CF3 COO)2

The copper salt of trifluoroacetic acid, Cu(CF₃ COO)₂ , offers a new platform to investigate the quantum ground states of low-dimensional magnets. In practice, it realizes the ideal case of a solid hosting essentially isolated magnetic monolayers. These entities are constituted by well-separated two-leg half-integer spin ladders organized in a zigzag fashion. The ladders are comprised of dimeric units of edge-sharing tetragonal pyramids coupled through carbon ions. The spin-gap state in this compound was revealed by static and dynamic magnetic measurements. No indications of long range magnetic ordering down to liquid helium temperature were obtained in specific heat measurements. First principles calculations allow estimation of the main exchange interaction parameters, J_⊥ =176 K and J_∥ =12 K, consistent with the weakly interacting dimers model.

[(INFESTATION OF FISHES OF THE FAMILY CYPRINIDAE IN THE FOCI OF TREMATODES OF THE ECOSYSTEM OF THE BELAYA RIVER (THE REPUBLIC OF BASHKORTOSTAN)]

In the ecosystem of the Belaya River, fishes of the family Cyprinidae were infected with three epidemically important species oftrematodes of the family Opisthorchidae: Opisthorchisfelineus, Metorchis bilis, and Pseudamphistomum truncatumn. No biotopes of mollusks of the genus Codiella were detected. The contamination of underyearlings with-Ofelineus and M.bilis metacercariae indicates that there are cores of opisthorchiasis and metorchiasis (M.bifis) foci in the ecosystem of the lower course of the river. The presence of biotopes of the genus Bithynia mollusks, the first intermediate host.for P. truncatum, in the waters, but the absence of fishes infected with P.truncatum metacercariae among the examined under- yearlings may lead to the conclusion that there are no cores of pseudamphistomiasis foci. Infestation of onein 97 older individual muvarica (Albumus alburnus) with trematode metacercariae is evidence of its infection outside the floodplain river ecosystems of the Belaya River and subsequent migration of the fish into the lowerreaches of the river, where a barren zone of a pseudamphistomiass focus is formed. In this ecosystem there is a risk of human infection with epidemically important species of trematodes of the family Opisthorchidae (O.felineus, M.bifis, and P.truncatum)-when eating the fish caught in the river, its tributaries, and floodplain waterbodies. When identifying the metacercariae and detecting the natural foci of trematodes, it is necessary to take into account the fact that the fishes of the family Cyprinidae in the river ecosystem have four types of Opisthorchis metacercariae (after D.A.Razmashkin).

Orbitally induced hierarchy of exchange interactions in the zigzag antiferromagnetic state of honeycomb silver delafossite Ag3Co2SbO6

We report the revised crystal structure, static and dynamic magnetic properties of quasi-two dimensional honeycomb-lattice silver delafossite Ag3Co2SbO6. The magnetic susceptibility and specific heat data are consistent with the onset of antiferromagnetic long range order at low temperatures with Néel temperature TN ∼ 21.2 K. In addition, the magnetization curves revealed a field-induced (spin-flop type) transition below TN in moderate magnetic fields. The GGA+U calculations show the importance of the orbital degrees of freedom, which maintain a hierarchy of exchange interaction in the system. The strongest antiferromagnetic exchange coupling was found in the shortest Co-Co pairs and is due to direct and superexchange interaction between the half-filled xz + yz orbitals pointing directly to each other. The other four out of six nearest neighbor exchanges within the cobalt hexagon are suppressed, since for these bonds the active half-filled orbitals turned out to be parallel and do not overlap. The electron spin resonance (ESR) spectra reveal a broad absorption line attributed to the Co(2+) ion in an octahedral coordination with an average effective g-factor g = 2.40 ± 0.05 at room temperature and show strong divergence of the ESR parameters below ∼150 K, which implies an extended region of short-range correlations. Based on the results of magnetic and thermodynamic studies in applied fields, we propose a magnetic phase diagram for the new honeycomb-lattice delafossite.

Successive spin orderings of tungstate-bridged Li2Ni(WO4)2 of spin 1

Magnetic, thermodynamic, and dielectric properties of Li2Ni(WO4)2 of S  =  1 system have been studied using magnetic susceptibility, specific heat, and dielectric constant measurements. The magnetic orderings can be identified in three stages, including a short range magnetic ordering indicated by the rounded χ(T) peak with maximum at  ∼20 K, and signatures of two successful antiferromagnetic long range orderings near T(N1) ~ 18 K and T(N2) ~ 13 K revealed by the d(χ(T)) /d(T) peaks. The successive long range magnetic orderings are related to the quasi triangular symmetry breaking in the ac- and bc-planes and to the change of the dielectric constant, suggesting the presence of spin-phonon coupling. The specific heat and magnetic entropy analysis for Li2Ni(WO4)2 shows the existence of a significant low dimensional magnetic correlations at high temperature and confirms the long range three-dimensional (3D) behavior of magnetic orderings below T(N1) and T(N2).

[EPIZOOTOLOGICAL CHARACTERIZATION OF TREMATODIASIS FOCI IN THE ECOSYSTEM OF THE AMUR RIVER IN THE KHABAROVSK TERRITORY]

Investigations were conducted in late June to early June 2013. The population density of mollusks of the genus Juga in the shoreline and littoral covered by meadow waters was 10 to 30 specimens/m2; there were solitary specimens of the genus Parafossarulus. Fourteen out of 39 fish species were invaded by metacercariae of Clonorchis. Manchurian spiny loaches (Leptobotia) and Light's bitterling (Rhodeus lighti) are first registered to be hosts of Clonorchis. The metacercariae of Metagonimus yokogawai were detected in silver carp (Hypophthalmichthys molitrix) and those of Nanophyetus salmincola schikhobalowi were in the kidneys, fin muscles, and gills of taimen (Hucho) and lenok (Brachymystax lenok) from the Khor River. The invasion rate for the taimen was greater than 1000 metacercariae and that for the lenok was not more than 720 metacercariae per fish.

[THE ENVIRONMENTAL BASES AND MECHANISM FOR NATURAL OPISTHORCHIASIS FOCUS PULSATION IN THE COMBINED FOCUS OF OPISTHORCHIASIS AND TULAREMIA]

A cyclic change in the epizootic activity of a tularemia activity underlies the mechanism of natural opisthorchiasis focus pulsation in the combined focus of opisthorchiasis and tularemia in the ecosystem of the Konda River. This is due to mass breeding and depression in the water vole (Arvicola terrestris) population. The mass breeding is predetermined by high population reproduction constants. The rodents' potential fecundity occurs with the high capacity of lands, which is caused by the hydrological regime of rivers. The size depression is predetermined by the epizootics of tularemia. The water vole is a host of the pathogens of opisthorchiasis and tularemia. So the mass rodent breeding in the combined infection and invasion focus causes an increase in the number of real invasion sources. The epizootic of tularemia is responsible for elimination of these invasion sources and for decreases in the flow of invasion material, the infection rate of Codiella and hence the amount of their produced cercarae, the extensive and intensive indicators of fish contamination, and the intensity of an epizootic process in the opisthorchiasis focus.

[Epizootiological characteristics of clonorchiasis foci in the Amur River ecosystem in the Jewish autonomic region]

Malacofaunal and ichthyoparasitological studies were conducted in the floodplain-river ecosystem in the middle course of the Amur River. The studies covered its channels and tributaries, such as Big and Small Bira, Bidzhan, In, and Vertoprashikha Rivers, in the Birobidzhan, Leninskoye, and Smidovich districts of the Jewish Autonomic Region in the second half of August 2011. It was established that there were biotopes of the mollusk Parafossalurus manchouricus, the first intermediate host of Clonorchis sinensis, in the exosystems of the In, Bira, and Bidzhan Rivers. Sporadic P. manchouricus specimens were found in the Bidzhan channel in the vicinity of its estuary and on the flooded bank of the In River. The bay of the Bira River (the town of Birobidzhan) exhibited a biotope of P. manchouricus with a mollusk population density of 180 to 300 specimens/m2. Seven of 16 examined fish species showed metacercariae of Clonorchis. Among them there were not only Cyprinidae, but also representatives of other families and orders. The two-year-olds of orca-skripuns (Pseudobagrus fulvidraco), orca-whips (Tachysyrus ussuriensis), and Brazhnikov's orsas (Liocassis braschnikowi) were infected with C. sinensis metacercariae. Clonorchis metacercariae were first detected in Amur sleepers (Percottus glehni). This fish species has not been heretofore recorded as the second intermediate host ofC. sinensis. The highest invasion extent for C. sinensis metacercariae was revealed in Amur bitterlings (Rhodeus sericeus) born during the current year. In the biotopes ofdifferent water reservoirs, it changed from 10.0 to 48.0%. In 4 of 6 water reservoirs, Amur bitterlings were found to have larvae of this species of trematodes. The invasion rates were in the range from 1 to 4 metacercariae per fish. Only in individual cases, they were as great as 28 parasitic larvae per fish.

[The environmental conditions and predictors of formation of the bases for a combination of Diphyllobothrium dendriticum and Triaenophorus nodulosus foci in the flood-river ecosystem of the Angara River]

Investigations were conducted in the context of the landscape-biocenological concept. The formation of water-storage basins in the valley of the Angara River was shown to give rise to the transformation of the morphological structure and hydrological regimen of a landscape, which determined a change in some environmental conditions and factors of a combination of foci and the emergence of others. The morphological structure and hydrological regimen of a landscape, the species composition of ecosystems, the populations of hosts, and their biocenotic relations were transformed due to the direct anthropogenic impact on the landscape. There was an emergence of populations of pathogens, parasitic systems of foci, their functional and spatial structures and a formation of invasion foci as the ecosystems of water-storage basins were transformed. There changes were responsible for the formation of an anthropurgic focus of D. dendriticum and a two-host population-combined natural-anthropurgic focus of diphyllobothriasis - Triaenophorus infection. The susceptibility of hosts, the polyhostality of pathogens, and the mechanisms of their transmission are environmental factors that predetermine the formation of epizootic bases for a combination of foci and, being evolutionally formed and relatively strictly determined, have not undergone cardinal changes in the anthropologically transformed landscape.

Peierls mechanism of the metal-insulator transition in ferromagnetic hollandite K2Cr8O16

Synchrotron x-ray diffraction experiment shows that the metal-insulator transition occurring in a ferromagnetic state of a hollandite K(2)Cr(8)O(16) is accompanied by a structural distortion from the tetragonal I4/m to monoclinic P112(1)/a phase with a √2×√2×1 supercell. Detailed electronic structure calculations demonstrate that the metal-insulator transition is caused by a Peierls instability in the quasi-one-dimensional column structure made of four coupled Cr-O chains running in the c direction, leading to the formation of tetramers of Cr ions below the transition temperature. This provides a rare example of the Peierls transition of fully spin-polarized electron systems.

Crystal field splitting in correlated systems with negative charge-transfer gap

Special features of the crystal field splitting of d-levels in the transition metal compounds with small or negative charge-transfer gaps Δ(CT) are considered. We show that in this case the Coulomb term and the covalent contribution to the t(2g)-e(g) splitting have different signs. In order to check theoretical predictions we carried out ab initio band structure calculations for Cs(2)Au(2)Cl(6), in which the charge-transfer gap is negative, so that the d-electrons predominantly occupy low-lying bonding states. For these states the e(g)-levels lie below the t(2g) ones, which demonstrates that at least in this case the influence of the p-d covalency on the total value of the crystal field splitting is stronger than the Coulomb interaction (which would lead to the opposite level order). We also show that the states in the conduction band are made predominantly of p-states of ligands (Cl), with a small admixture of d-states of Au.

[Mechanisms for the formation of a combination of the natural foci of trematodiases and tularemia in the floodplain-river ecosystem of the Konda River in different periods of epizootic activity of an infection focus]

The basis of the mechanism responsible for the formation of a combination of the natural foci of trematodiases and tularemia in the infection foci in the interepizootic periods is their association with the morphological structure of the floodplain-river landscape of the Konda River. The landscape's facias and holes, which are common to the foci, are integrated, by predetermining the territorial combination. The formation of a closed trinomial Francisella tularensis parasite system integrating these foci serves as a basis for the mechanism of the formation of a combination of the natural foci of trematodiases and tularemia on transition of the latter from the interepizootic state to epizooty. The absence of host populations linking the foci of methorchiasis (M. xanthosomus), bilharziasis, and tularemia determines their combination both in the interepizootic periods and at the level of the landscape morphological structure. The basis for the mechanism of the formation of a combination of the natural foci of trematodiases and tularemia in the periods of diffuse epizooties in the infection foci is the formation of an open binomial F. tularensis parasite system and the infestation of the co-members of F. tularensis trematode parasite systems. By penetrating into them, the pathogen forces the F. tularensis parasite system to enter the trematode parasite systems, causing their complete (opisthorchiases, methorchiases) or partial (bilharziasis) coincidence. Thus, these foci are combined at the level of parasitocenoses of the parasite systems of infections and infestations, by giving rise to pseudosystem combined foci. The natural foci of B. polonica and F. tularensis are combined at the level of parasitocenosis of the coacting hemipopulation of trematode parthenitas, F. tularensis subpopulations and intermediate host population, by forming an autoecious population-combination bilharziasis-tularemia focus. The formation of territorial-combination, autoecious population-combination, and pseudosystem-combination foci of trematodiases and tularemia in different periods of the epizootic activity of an infection focus is determined by the functional organization of the parasite system of a tularemia focus and the biocenotic (functional) structure of natural foci of infestations.

[The landscape-biocenological concept of a combination of natural foci of diseases. Environmental conditions predetermining the formation of biotic and epizootic bases for a combination of natural foci of diseases]

The potential of a combination of foci of diseases is not limited by environmental conditions. The biotic and epizootic bases for the combination of foci are formed under the influence of the environmental factors predetermining the formation of the bases for the combination of the foci. These are pathogen populations, parasitic systems of foci with forming parasitocenoses, the functional and spatial pattern of the foci, susceptibility of hosts (vectors), polyhostality of pathogens and mechanisms of their transmission. The author places emphasis on the fact that any single factor cannot serve as a basis for the combination of the foci since the combination bases form only when pairs of identical factors interact. He points to the interrelation and correlation of the considered bases for the combination of the foci. The combination of invasion foci is noted to be effected in the absence of mixed infectiousness of specimens. The coacting parasitic systems of foci are predetermined to manifest themselves as the underlying biotic bases that determines the type of the combination of foci. The level of the combination of parasitic systems of the foci is predetermined by the parasitocenoses of coacting populations of pathogens and hosts (parasitic systems). The interacting functional and spatial patterns of the foci predetermine the latter's community, by acting as biotic bases for the combination. The susceptibility of hosts (vectors) and the polyhostality predetermine a range of interacting parasitic systems. The polymorphism of the types of hosts determines the functional strength of parasitic systems, by predetermining the stability of a combination of foci. The interacting identical mechanisms of transmission act as an epizootic basis for the combination of the foci. The continuity of the biotic and epizootic bases for the combination of the foci is stated.

[The landscape-biocenological concept of a combination of natural foci of diseases. Environmental conditions predetermining the formation of abiotic and biotic bases for a combination of natural foci of diseases]

Current approaches to studying the problem of a combination of natural foci of diseases are analyzed. It is noted that the essence of a combination of natural foci of infection is understood as the simultaneous existence of two foci or more on the given territory or as infection of individuals of hosts (vectors) with two species (or more) of causative agents. It is pointed out that the combination of foci of diseases from the biocenological standpoints is considered in none of the papers. The author states that all investigators analyze the problem in the context of parasitology that is a section of autecology rather than in the context of biocenology considering the interaction of populations. No conception of the combination of natural foci of diseases and an appropriate approach to studying the problem is a main neglect in the consideration of their combination till recently. Fundamental provisions of biocenology, population ecology, ecological parasitology, the teaching of parasitocenoses and the concept of the landscape morphological structure must serve as a basis for the methodology of studying the combination of the foci. The author considers the combination to be an interaction of the foci of diseases on the bases that presuppose the presence of environmental conditions predetermining the formation of abiotic and biotic bases of the combination of the foci. These include the morphological structure and hydrological conditions of a landscape, species-specific composition of biocenotic ecosystems, the populations of hosts (vectors) of causative agents, and their biocenotic ties. The continuity of the biotic and abiotic bases of the combination of the natural foci ofdiseases is stated.

Electronic and magnetic structure for the spin-gapped system CuTe(2)O(5)

The results of the calculation of the electronic and magnetic properties for the spin-gapped material CuTe(2)O(5) are presented. The direct computation of exchange constants J in the framework of the LDA+U shows that the largest exchange coupling in CuTe(2)O(5) is found between fourth nearest neighbors, as was argued by Das et al (2008 Phys. Rev. 77 224437), and that this compound should be considered as the two-dimensional coupled dimer system.

[Ecological bases of the combination of natural foci of leptospirosis, tick-borne encephalitis, and ixodes tick-borne borrelioses in the ecosystems of a northern forest-steppe subzone in the Tyumen region]

In the context of the present-day teaching of parasitocenoses and the proposition that the pathogen's population is the only compulsory and specific component of a natural focus, the authors bring to light the ecological bases of the combination of natural foci of leptospirosis and tick-borne encephalitis, leptospirosis and Ixodes tick-borne borrelioses. These foci are one-host population-combined. While analyzing the combination of the foci, it is expedient to consider in pairs since this provides a way of identifying the combination bases that are unique to these foci and determining the level, pattern, type, and degree of the combination of foci and, on their basis, the type of a combined focus. By determining the confined pattern of foci of leptospirosis, tick-borne encephalitis, and Ixodes tick-borne borrelioses to the same elements of a landscape, the morphological structure of the northern forest-steppe landscape of the Tyumen Region predetermines their relationship, by acting as the abiotic basis of the combination of foci. Despite the differences in the types of the parasitic systems and the absence of the same mechanism of transmission of causative agents, the natural foci of leptospirosis, tick-borne encephalitis, and Ixodes tick-borne borrelioses are, nevertheless, combined at the level of parasitocenosis of the co-acting populations of pathogenic organisms and their reservoir hosts act as the biotic bases of the combination of foci of leptospirosis, tick-borne encephalitis, and Ixodes tick-borne borrelioses. The susceptibility of Cl. rutilus and S. araneus to infection with the pathogens ofleptospirosis, tick-borne encephalitis, and Ixodes tick-borne borrelioses and multihost pattern of the causative agents act as the epizootic bases of a combination of the foci of leptospirosis, tick-borne encephalitis, and Ixodes tick-borne borrelioses. It has been shown that the biotic, epizootic, and abiotic bases of a combination of the natural foci of leptospirosis, tick-borne encephalitis, and Ixodes tick-borne borrelioses of the Javanica serogroup are, in the aggregate, the ecological bases of the combination of these foci.

[Ecological bases of the combination of natural foci of Trematoda infections in the floodplain-river ecosystem of the Konda River. Communication 2. Host population-combined foci of Trematoda infections]

In the context of the present-day teaching of parasitocenoses and the proposition that the pathogen's population is the only compulsory and specific component of a natural focus, the author discloses the ecological bases of the combination of natural foci of opisthorchiasis and methorchiasis (M. bilis), methorchiasis (M. bilis) and methorchiasis (M. xanthosomus). These foci are host population-combined. While analyzing the combination of foci, it is expedient to consider them in pairs since this provides a way of identifying only the combination bases that are unique to these foci. The parasitic systems of flukes, the parasitocenoses of co-acting parasitic systems of "twin types", the structure of foci, the species-specific composition of ecosystems, and the ecological relations of the Opisthorchis fluke hosts act as the biotic bases of a combination of foci of Trematoda infections. By coinciding, the multihost hemipopulations of parasites and the susceptibility of host populations predetermine the combination of Opisthorchis fluke foci. The susceptibility of hosts, the multihost pattern of Opisthorchis flukes, the identity of parasitic systems, and the common mechanism of pathogen transmission act as the epizootic bases of a combination of invasion foci. The morphological structure and hydrological regime of a landscape act as the abiotic bases of a combination of foci. The hydrological regime is by its nature a universal mechanism of pathogen transmission. The foci of Opisthorchis flukes at the level of parasitocenosis of metacercarium populations and fish populations in the Konda River ecosystem are combined in the age groups of only carp (Cyprinidae) underyearlings and yearlings. The abiotic, biotic, and epizootic bases of a combination of natural foci of Opisthorchis flukes are, in the aggregate, the ecological bases of a combination of foci.

[Ecological bases of the combination of natural foci of Trematoda infections. 1. One- and two-host population-combined foci of Trematoda infections in the floodplain-river ecosystem of the Konda River]

In the context of the present-day teaching of parasitocenoses and the proposition that the pathogen's population is the only compulsory and specific component of a natural focus, the author brings to light the ecological bases of the combination of natural foci of metorchiases, bilharziasis, opisthorchiasis, and methorchiasis (M. xanthosomus). Two first foci are one-host population-combined and the latter focus is a two-host population-combined focus. While analyzing the combination of foci, it is expedient to consider in pairs since this provides a way of identifying the bases of the combination, which are unique to these foci, and determining the level, pattern, type, and degree of the combination of foci and, on their basis, the type of a combined focus. It is noted that in biohelminthiases, detection of even hemipopulations of parasites points to the presence of natural foci. The morphological structure of the floodplain-river landscape of the Konda River acts as the abiotic basis of the combination of foci. The parasitic systems of flukes, the parasitocenoses of co-acting hemipopulations of the pathogens and populations of hosts, the structure of foci, the species-specific composition of ecosystems, and the ecological relations of Trematoda hosts act as the biotic bases of the combination of foci of Trematoda infections. The host susceptibility to infection with Trematoda hemipopulations and the multihostality of B. polonica and M. xanthosomus act as the epizootic bases of the combination of foci. The abiotic, biotic, and epizootic bases of the combination are, in the aggregate, the ecological bases of the combination of natural foci of zoonoses.

[Assessment of mineral density of bone tissue in patients with rheumatoid arthritis using ultrasonic osteometry]

AIM

To examine bone mineral density in rheumatoid arthritis (RA) patients using echoosteometry (EOM), to analyze the speed of ultrasound bone conduction in patients with different variants of RA.

MATERIAL AND METHODS

The study included 122 patients with verified RA diagnosis (ARA, 1987) who had not previously taken glucocorticosteroids, basic drugs or antiosteoporosis therapy. Group 1 consisted of 48 women of reproductive age, group 2--of 46 postmenopausal women and group 3 of 28 male patients. EOM measured the speed of ultrasonic conduction in collar-bones and radii (Echoosteometer EOM-02).

RESULTS

The speed of ultrasound conduction in collar-bones and radii in RA patients is slower than control. This shows bone density loss. EOM demonstrated correlations between ultrasound bone conduction and RA patients age, RA duration and x-ray stage of the disease.

[Normovolemic hemodilution of autologous fresh frozen plasma in surgery of the spinal cord in children]

The authors describe results of using autologous chilled plasma in making acute normovolemic hemodilution with exfusion of 20% of the circulating blood volume in 38 children of 6-16 years of age in planned surgery of the spinal cord. The autologous chilled plasma was also included in the intraoperative infusion-transfusion program. The average blood loss was 32% of the circulating blood volume. No complications were noted. The method allows to refuse of using donor blood components in blood loss as great as 45%.

[The fundamentals of association of natural foci of zoonoses]

Reports on the role of hydrological conditions in the functioning of parasitic systems are analyzed. The authors point out that a range of issues including different aspects of combination phenomena is discussed there. They suggest that a concept of combination shall be replaced by a concept of association of parasitic systems and their relevant natural foci of zoonoses, which is of a larger scope. The fundamentals of the formation and functioning of associated parasitic systems and natural foci of zoonoses are discussed. These include the hydrological conditions of floodplain-river regions, the multiparasitic capacity of hosts and vectors, the multihost pattern of causative agents, and a diversity of mechanisms of their transmission. The transmission mechanism without which movement of causative agents and the existence of parasitic systems and foci are impossible is shown to be a global combining onset of parasitic systems. The hydrological conditions of floodplain-river regions act as the universal mechanism of transmission of pathogens. The dynamics of the mechanism determines the functioning of all other mechanisms of transmission.

[The pathogenetic aspects of diabetic involvement of the heart]

As many as 107 patients with diabetes mellitus were enrolled in the study. It has been found out that under diabetic metabolic disturbances there occur significant changes in structural-and-functional characteristics of proteins, including myocardial ones, believed to be of much importance to the pathogenesis of diabetic affection of the heart and to the functional state of the myocardium.