Pronounced Confinement Research Articles

Analysis of cases of brucellosis in humans and molecular-biological characteristics of <i>Brucella melitensis</i> strains in regions of South European Russia with a high brucellosis incidence

Introduction. To improve the epidemiological surveillance of brucellosis in Russia, a detailed analysis of incidence and characteristics of Brucella melitensis strains circulating in the territories of the country where there is a persistent epizootic and epidemiological problem with brucellosis is required.Purpose of the study. To study current trends in the brucellosis epidemic process and perform molecular analysis of Brucella isolates from the territories of Southern and North Caucasian Federal Districts with long lasting unfavorable situation with brucellosis — the Republics of Dagestan (RD), Kalmykia (RK) and Stavropol Krai (SK).Materials and methods. The analysis of the brucellosis incidence in the North Caucasus Federal District and the Southern Federal District was carried out on the basis of data from the Rospotrebnadzor Departments for the period 2011–2020. Total 56 cultures of Brucella melitensis, isolated in 1999–2019 from patients with brucellosis that permanently resided in RD, RK and SK were studied.Results. The key factor contributing to the epidemic manifestations of brucellosis in the south of the European part of Russia is the persistence of epizootic foci in cattle and small ruminants. The leading concomitant factors are as follows: the presence in the region of "hidden" epizootic foci, uncontrolled production of food products of animal husbandry and its illegal sale to customers, unauthorized movement of animals and livestock products, untimely delivery (concealment) of sick cattle for stamping out. Results of molecular analysis of B. melitensis strains indicate the circulation of a mixed population of brucella, which is generally characteristic of the entire region, without a pronounced confinement of isolates to separate administrative territories. At the same time, the entire studied sample of strains can be divided into two groups (72% and 28% of strains) based on MLVA-16 genotypes by the variability in the Bruce 19 locus, which makes it possible to associate a part of the studied strains with the territory of their isolation.Discussion. The data obtained make it possible to scientifically substantiate the possibility of considering the affected territories of the Southern Federal District and the North Caucasian Federal District as a single common persistent active anthropurgic epizootic focus with circulation of a mixed, but typical for the region population of Brucella strains.

The role of magnetic fields in the formation and propagation of hadronic microquasars jets

In the present work, we examine the role of the magnetic field (MF), which causes a rather pronounced confinement of the jets at microquasars. Due to radial Lorentz forces acting on the jet’s matter towards the jet’s axis, the outgoing flux is collimated along the same axis and vertically to the compact object. Alternatively, a rotating central object may drag the surrounding MF into collimation around the produced jet. In such objects, jet emerges from each side of the accretion disc.These jets operate as cosmic engines, capable of accelerating particles on very high energies (~10^2 TeV) and consist sources of high energy neutrinos and gamma rays. We also examine the role of the MF, which causes to a rather pronounced jet confinement. Our aim is to investigate and model its role on various physical observables of the jet, by simulating the jet’s flow and derive 2D and 3D visualizations and furthermore examine its effect on the neutrino emissivity.

Structure, nanomechanics, and dynamics of dispersed surfactant‐free clay nanocomposite films

The current work presents a new approach to achieve high quality dispersion of surfactant‐free nanoclay tactoid particles in sub‐micron thin films despite the absence of organic modifier. Natural Montmorillonite particles, Cloisite, were dispersed in thin films of polycaprolactone (PCL) through a flow coating technique assisted by ultra‐sonication. Wide‐angle X‐ray scattering (WAXS), grazing‐incidence wide‐angle X‐ray scattering (GI‐WAXS), and transmission electron microscopy (TEM) were used to confirm the level of natural clay dispersion down to the level of tactoids (sub‐micron scale stacks of clay sheets). These characterization techniques were carried out in conjunction with an analysis of nanomechanical properties via strain‐induced buckling instability for modulus measurements (SIEBIMM), a high‐throughput technique to characterize thin film mechanical properties. The buckling patterns indicate that the natural clay tactoids separate buckling‐enhancing (high‐modulus) crystalline regions and interconnect buckling‐suppressing amorphous (low‐modulus) regions. Due to the tactoid length scale, the glass transition behavior of the composites as characterized by broadband dielectric relaxation spectroscopy was unmodified by the clay. Likewise, the glass transition temperature, Tg, and fragility (slope of relaxation time behavior approaching Tg), remain unaffected, indicating that these dispersed tactoids do not induce pronounced confinement effects on dynamics. POLYM. ENG. SCI., 58:1285–1295, 2018. © 2018 Society of Plastics Engineers

ATM Alters the Otherwise Robust Chromatin Mobility at Sites of DNA Double-Strand Breaks (DSBs) in Human Cells

Ionizing radiation induces DNA double strand breaks (DSBs) which can lead to the formation of chromosome rearrangements through error prone repair. In mammalian cells the positional stability of chromatin contributes to the maintenance of genome integrity. DSBs exhibit only a small, submicron scale diffusive mobility, but a slight increase in the mobility of chromatin domains by the induction of DSBs might influence repair fidelity and the formation of translocations. The radiation-induced local DNA decondensation in the vicinity of DSBs is one factor potentially enhancing the mobility of DSB-containing chromatin domains. Therefore in this study we focus on the influence of different chromatin modifying proteins, known to be activated by the DNA damage response, on the mobility of DSBs. IRIF (ionizing radiation induced foci) in U2OS cells stably expressing 53BP1-GFP were used as a surrogate marker of DSBs. Low angle charged particle irradiation, known to trigger a pronounced DNA decondensation, was used for the defined induction of linear tracks of IRIF. Our results show that movement of IRIF is independent of the investigated chromatin modifying proteins like ACF1 or PARP1 and PARG. Also depletion of proteins that tether DNA strands like MRE11 and cohesin did not alter IRIF dynamics significantly. Inhibition of ATM, a key component of DNA damage response signaling, resulted in a pronounced confinement of DSB mobility, which might be attributed to a diminished radiation induced decondensation. This confinement following ATM inhibition was confirmed using X-rays, proving that this effect is not restricted to densely ionizing radiation. In conclusion, repair sites of DSBs exhibit a limited mobility on a small spatial scale that is mainly unaffected by depletion of single remodeling or DNA tethering proteins. However, it relies on functional ATM kinase which is considered to influence the chromatin structure after irradiation.

Continuous Freezing of Argon in Completely Filled Mesopores

We have studied the phase transition of argon in completely filled mesopores. Our effective medium analysis of ultrasonic measurements clearly indicates a continuous phase transition of argon in completely filled pores over a broad temperature range of about 45 K. With decreasing temperature, the amount of frozen argon increases and below about 30 K all adsorbed argon (including the first few layers near the pore wall) is frozen with a shear modulus about equal to the bulk shear modulus. It is remarkable, that in a system showing such a pronounced confinement effect--a continuous phase transition over 45 K--the bulk properties are preserved. A comparison with temperature cycles with one and two adsorbed layers shows, that due to the presence of solid argon in the center of the pores the first few layers are already frozen at a higher temperature (30 K) compared to single layers (20 K). The transfer of our technique from the simple model system that we present in this Letter to other more complex adsorbates and different porous samples should help to enlighten the phase behavior under confinement in further studies.

Guest–host interactions of arenes in H-ZSM-5 and their impact on methanol-to-hydrocarbons deactivation processes

The acidic zeolite H-ZSM-5 is a widely used catalyst in industrial methanol-to-hydrocarbons (MTH) conversion, due to its pronounced stability to the formation of unreactive arenes that degrade the catalyst. In the present work, adsorption of a series of mono- and polycyclic arenes in H-ZSM-5 is modeled through periodic density functional theory calculations on the complete unit cell employing the BEEF-vdW functional. Polycyclic arenes are predicted to fit in the zeolite framework, the preferred adsorption site being the intersection region between the straight and sinusoidal channels. Supporting recent experimental results, an adsorbate orientation along the straight channel is predicted. A pronounced confinement of the arenes governs their directional interaction with acid sites. From the findings, it is plausible that deactivation of H-ZSM-5 during MTH conversion is caused by polycyclic arenes growing in the straight channels near the outer surface of the zeolite crystal on which they join to form graphitic layers.

Pore Size Effects on the Sorption of Supercritical CO2 in Mesoporous CPG-10 Silica

Excess sorption isotherms of supercritical carbon dioxide in mesoporous CPG-10 silica glasses with nominal pore sizes of 7.5 and 35 nm were measured gravimetrically at 35 and 50 °C and pressures of 0–200 bar. Formation of broad maxima in the excess sorption was observed at fluid densities below the bulk critical density. Positive values of excess sorption were measured at bulk densities below 0.7 g/cm3, i.e., the interfacial fluid is denser than the bulk fluid at low pressures. Zero and negative values were obtained at higher densities, i.e., the adsorbed fluid becomes equal to and eventually less dense than the corresponding bulk fluid. Pronounced confinement effects on sorption behavior have been found and further analyzed by normalizing the excess sorption to the adsorbent surface area and pore volume, yielding new insight into supercritical fluid adsorption in this range of pore sizes and P, T conditions. If normalized to the specific surface area, the excess sorption is higher for the 35 nm pore size material, but the pore volume normalized excess sorption is higher for the 7.5 nm pore size material. With increasing pore width, the excess sorption peak position shifts to higher pressure. Both CPG-10 materials exhibit regions of constant mean pore fluid density as a function of bulk CO2 density at 35 °C but not at 50 °C. This region is located between the excess sorption peak maximum and the adsorption/depletion transition point. Applied to the situation of CO2 sequestration in dry sandstone formations, the results of this study indicate that carbon storage capacity is enhanced by sorption effects, particularly at low temperature and in narrow pores with high surface to volume ratios.

Structure Evolution in Amylopectin/Ethylene Glycol Mixtures by H-bond Formation and Phase Separation Studied with Dielectric Relaxation Spectroscopy

The interaction between amylopectin, a starch polysaccharide, and ethylene glycol (EG) was investigated using broad-band dielectric relaxation spectroscopy. Water-free amylopectin (AP) was mixed with 21 wt % ethylene glycol. This resulted in a continuous ethylene glycol phase, as well as a molecularly mixed AP/EG fraction. After storage at room temperature or annealing, the mixture shows dynamic properties typical of a polymer with weak intermolecular interactions, suggesting that EG binds preferentially to AP and forms intrachain H-bridges leading to increased chain stiffness and thus an increased glass transition temperature. This structure evolution is accompanied by a sharp reduction in the size of the ethylene glycol droplets to a few nanometers, as revealed by pronounced confinement effects in the α-relaxation of the dispersed EG.