Spherical gearing with intermediate ball elements: parameter ranges with a high contact ratio

The paper presents analytical research of the geometry and kinematical parameters of spherical gearing with ball intermediate elements. The main attention is paid to the influence of the offset coefficient on the tooth geometry generation, the contact ratio and the motion transmission angle. Intermediate ball element racetracks on the gear are trochoidal curves on a spherical surface. Two areas for the offset coefficient values providing a high value of the contact ratio – basic trochoid (without offset) and prolate trochoid with abutting racetracks of adjacent ball elements ― were revealed. Analysis of the investigated parameters showed that for power transmission, it is preferable to use spherical gearing without an offset, and for kinematic transmission, it is possible to use profiles with a large offset. The present study allows making a rational choice of geometrical parameters depending on the transmission predestination

The study of the effect of aluminum powders dispersion on the oxidation and kinetic characteristics

Differential-scanning calorimetry (DSC) and thermogravimetric analysis (TG) were used to study micro-sized aluminum powder ASD-4 and nano-sized powder Alex. The dependence of the oxidation process on the dispersion of the sample particles is shown. The influence of thermogravimetric conditions on the thermal regime of the process was considered, and its kinetic parameters were determined. Calculations of the activation energy and the pre-exponential factor were carried out

Phase diagram and isotope effect in (PrEu)_0.7Ca_0.3CoO_3 cobaltites exhibiting spin-state transitions

We present the study of magnetization, thermal expansion, specific heat, resistivity, and a.c. susceptibility of (Pr$_{1-y}$Eu$_y$)$_{0.7}$Ca$_{0.3}$CoO$_3$ cobaltites. The measurements were performed on ceramic samples with $y = 0.12 - 0.26$ and $y = 1$. Based on these results, we construct the phase diagram, including magnetic and spin-state transitions. The transition from the low- to intermediate-spin state is observed for the samples with $y > 0.18$, whereas for a lower Eu-doping level, there are no spin-state transitions, but a crossover between the ferromagnetic and paramagnetic states occurs. The effect of oxygen isotope substitution along with Eu doping on the magnetic/spin state is discussed. The oxygen-isotope substitution ($^{16}$O by $^{18}$O) is found to shift both the magnetic and spin-state phase boundaries to lower Eu concentrations. The isotope effect on the spin-state transition temperature ($y > 0.18$) is rather strong, but it is much weaker for the transition to a ferromagnetic state ($y < 0.18$). The ferromagnetic ordering in the low-Eu doped samples is shown to be promoted by the Co$^{4+}$ ions, which favor the formation of the intermediate-spin state of neighboring Co$^{3+}$ ions.Comment: 13 pages, including 11 figures, to be published in Phys. Rev.

Features of the immune response in children with acute respiratory infections caused by DNA and RNA viruses

The issues of immunopathogenesis of acute respiratory viral infections (ARVI) remain relevant, despite a long history of study. The aim of the study was to investigate the characteristics of the content of some cytokines in the blood serum of children with ARVI caused by DNA and RNA-containing viruses. Material and methods. We examined 92 children with ARVI at the age from 1 to 15 years, hospitalized in the hospital of the Children’s Clinical Hospital No. 6 (Novosibirsk). In order to determine the etiological factor, a study was carried out using the RT-PCR method (test systems AmpliSensORVI-screen-FL, “InterLabService”, Russia) of mucus from the nose and throat for the presence of genetic material of viruses that cause ARVI. Determination of the content of IL-8, IL-17, IFN-γ in the blood serum in children of all groups was carried out by the method of solid-phase ELISA using commercial test systems of LLC “Cytokin” (Russia). Results and discussion. 4 groups were formed: group I (n = 20) children with ARVI caused by DNA-containing viruses (group B, C, E adenoviruses, bocaviruses); group II (n = 53) children with ARVI caused by RNA viruses (RS virus, metapneumovirus, parainfluenza viruses 1, 2, 3, 4, rhinovirus and coronoviruses); group III (n = 12) children with ARVI caused by mixed infection; group IV (n = 7) – the genetic material of the pathogen has not been isolated. Concentration of IL-8, IL-17, IFN-γ was significantly increased in all groups compared to the normative values. Higher values of IFN-γ and IL-8 were revealed in patients with DNA viruses compared with the group with RNA-containing viruses, although the excess of IFN-γ was not statistically significant. Differences in the content of IFN-γ, IL-8 and IL-17 were noted for various etiological viral agents, but they were not significant. Conclusions. The results obtained can serve as confirmation that the functional characteristics of the response of the immune system in children with ARVI are determined not so much by the etiological factor as by its individual state. With ARVI in children, the presence of genetic material from more than one virus, apparently, is not a significant potentiating factor in the activation of the immune response. At the same time, a negative PCR result with a detailed clinical picture of ARVI does not exclude the viral genesis of the disease

Modification of the ground state in Sm-Sr manganites by oxygen isotope substitution

The effect of $^{16}$O $\to$ $^{18}$O isotope substitution on electrical resistivity and magnetic susceptibility of Sm$_{1-x}$Sr$_x$MnO$_3$ manganites is analyzed. It is shown that the oxygen isotope substitution drastically affects the phase diagram at the crossover region between the ferromagnetic metal state and that of antiferromagnetic insulator (0.4 $< x <$ 0.6), and induces the metal-insulator transition at for $x$ = 0.475 and 0.5. The nature of antiferromagnetic insulator phase is discussed.Comment: 4 pages, 3 eps figures, RevTeX, submitted to Phys. Rev. Let

Photoproduction of pions and properties of baryon resonances from a Bonn-Gatchina partial wave analysis

Masses, widths and photocouplings of baryon resonances are determined in a coupled-channel partial wave analysis of a large variety of data. The Bonn-Gatchina partial wave formalism is extended to include a decomposition of t- and u-exchange amplitudes into individual partial waves. The multipole transition amplitudes for $\gamma p\to p\pi^0$ and $\gamma p\to n\pi^+$ are given and compared to results from other analyses.Comment: 18 pages, 14 figure

The effect of quercetin on oxidative stress markers and mitochondrial permeability transition in the heart of rats with type 2 diabetes

Increasing evidence suggests that oxidative stress and induction of mitochondrial permeability transition in cardiomyocytes are linked to tissue damage and the development of diabetic cardiovascular complications. The aim of this study was to assess the effects of quercetin (Q) on oxidative stress and mitochondrial permeability transition in the heart of rats with type 2 diabetes mellitus (DM). Type 2 DM was induced in 12-week-old male Wistar rats by intraperitoneal injections of 25 mg/kg streptozotocin twice per week followed by a high-fat diet during four weeks. The rats were divided into three groups: control intact group (C, n = 8), untreated diabetic group (Diabetes, n = 8) and diabetic rats treated with Q (50 mg/kg/day per os for 8 weeks) after diabetes induction (Diabetes+Q, n = 8). Administration of Q increased insulin sensitivity and normali­zed the functional state of cardiac mitochondria due to increased aconitase and succinate dehydrogenase activities in rats with type 2 DM. Q also ameliorated oxidative stress, decreasing the level of advanced oxidation protein products and increasing the activity of thioredoxin-reductase in heart mitochondria of diabetic rats. In addition, Ca2+-induced opening of the mitochondrial permeability transition pore was significantly inhibited in diabetic rats treated with Q in comparison with the untreated diabetic group. These data demonstrate that Q can protect against oxidative stress, mitochondrial permeability transition induction and mitochondrial dysfunction in cardiomyocytes of diabetic rats. We suggest that the use of Q may contribute to the amelioration of cardiovascular risk in type 2 DM

P-wave excited baryons from pion- and photo-induced hyperon production

We report evidence for $N(1710)P_{11}$, $N(1875)P_{11}$, $N(1900)P_{13}$, $\Delta(1600)P_{33}$, $\Delta(1910)P_{31}$, and $\Delta(1920)P_{33}$, and find indications that $N(1900)P_{13}$ might have a companion state at 1970\,MeV. The controversial $\Delta(1750)P_{31}$ is not seen. The evidence is derived from a study of data on pion- and photo-induced hyperon production, but other data are included as well. Most of the resonances reported here were found in the Karlsruhe-Helsinki (KH84) and the Carnegie-Mellon (CM) analyses but were challenged recently by the Data Analysis Center at GWU. Our analysis is constrained by the energy independent $\pi N$ scattering amplitudes from either KH84 or GWU. The two $\pi N$ amplitudes from KH84 or GWU, respectively, lead to slightly different $\pi N$ branching ratios of contributing resonances but the debated resonances are required in both series of fits.Comment: 22 pages, 28 figures. Some additional sets of data are adde

Polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei

The polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei are studied. It is pointed out that they open good perspectives to study the dynamics of dinucleons in the medium in detail. The ($\gamma,pp$) and ($\gamma,pn$) angular cross sections, photon asymmetries and outgoing nucleon polarizations are calculated for the target nuclei $^{16}$O and $^{12}$C and photonenergies ranging from 100 up to 500 MeV. It is investigated to which degree the two-nucleon emission reaction is dominated by photoabsorption on $^3S_1(T=0)$ proton-neutron and $^1S_0(T=1)$ proton-proton pairs in the nuclear medium. The calculations demonstrate that dominance of $S$ wave photoabsorption in the ($\gamma,pn$) channel does not necessarily imply that the reaction mechanism is similar to what is observed in deuteron photodisintegration.Comment: 27 pages, REVTeX 3.0 with epsf.sty, 11 figures in EPS forma