Dynamics of liquids with high viscosity contrast in unevenly rotating Hele-Shaw cell.

The paper is devoted to the experimental study of the dynamics of an interface between two liquids with high viscosity contrast filling a vertical, circular narrow gap rotating about a horizontal axis at a speed modulated by librations. The equilibrium shape and stability of the interphase boundary are considered. In the absence of librations, under the action of the centrifugal force the boundary has an axisymmetric shape. At librations, at certain frequency ratios, the interface loses its axisymmetric position: in the cavity reference frame, it is displaced in the radial direction. It is theoretically shown that the discovered phenomenon is explained by the average action of gravity; the results of experiments and theory are consistent. The experiments reveal that with an increase in the modulation amplitude the circular interface loses stability in a threshold manner: an azimuthally periodic relief, quasi-stationary in the cavity frame, emerges. This is associated with the Kelvin-Helmholtz instability due to tangential oscillations of the less viscous liquid near the interface. A dimensionless parameter that determines the stability of the interface is obtained in the limit of high dimensionless libration frequency. The stability threshold increases with the decrease in the dimensionless frequency. This article is part of the theme issue 'New trends in pattern formation and nonlinear dynamics of extended systems'.

A Ukrainian multicenter prospective study of the value of PET/ CT prognostic role in primary patients with Hodgkins lymphoma in a real-life cohort.

INTRODUCTION: In recent years, the positron emission tomography combined with computed tomography (PET/CT) has changed and the treatment approaches in Hodgkins lymphoma (HL) patients have entirely improved. The main idea in several studies is the use of PET/CT and the International Prognostic Score (IPS) protocols in identification of patients within a high-risk group and potential early relapse/refractory disease. MATERIALS AND METHODS: This study was based on PET/CT evaluation and treatment strategies of patients from eight Centers of Hematology in Ukraine. The patients included were newly dia-gnosed with HL and were aged 67 years or younger. They received a treatment with ABVD or BEACOPP-14/esc or “switched-regimens” (ABVD + BEACOPP-esc/14, BEACOPP-esc/14 + ABVD). The primary endpoints were to assess a correlation between PET/CT findings at the time of dia-gnosis, response to the therapy and clinical outcome (relapse/death) for patients with early and advanced stages of HL. The secondary endpoints were to evaluate the relationship between IPS and PET/CT findings. RESULTS: The study group included 106 patients. The overall response rate (ORR) was 90.5%. The ORR for patients with stages I-II was 96.5% (55/57) vs. 91% (41/45) for stage III-IV patients. In total, the disease progression occurred in 58.3% (7/12) of PET2+ patients and in 13.3% (12/90) of PET2 patients (P < 0.05). No significant difference was found between the event free survival (EFS) rate and IPS for patients with PET2+ vs. PET2, (log-rank test; P = 0.4). The PET3 status was found in 88.8% (79/89) of the study group patients and 1.2% (10/89) had a PET3+ status (P < 0.05). Using the Cox regression, we confirmed a significant correlation between EFS with PET3 Deauville scale (DS) and IPS. Patients with DS 1-2, DS 3 and DS 4-5 had a 1-year event-free survival of 94.4%, 100% and 33%, respectively (HR 0.56; 95% CI 1.07-2.8; P < 0.02). Our multivariable analysis showed no statistically significant correlation between PET2+ and PET3+ status and extranodal involvement or large tumor burden. CONCLUSION: The results of using PET/CT in patients with primary HL demonstrated a high prognostic value of PET at the end of the treatment. In addition, we confirmed the predictive role of IPS prognostic model in the treatment outcome depending on PET status.

Experimental data on the behavior of a heat-generating fluid in a rotating horizontal cylinder under transverse vibrations.

The paper presents experimental data on the effect of transverse vibrations on a heat-generating fluid in a rotating horizontal cylinder. To obtain the data, an original experimental device was designed and manufactured. The data of temperature measurements in the cavity depending on the angular velocity of rotation of the cavity, frequency and amplitude of vibrations are presented. To estimate the intensity and structure of convection, the velocity fields of fluid motion relative to the cavity in cross sections are shown. The paper is related to a research article "Convection of a heat-generating fluid in a rotating cylindrical cavity subject to transverse vibrations" Vjatkin et al, 2019.

Methods of experimental study of thermal convection in cavity subject to rotation and vibration.

Vibrations of a non-isothermal fluid result in the generation of an averaged flows - "thermal vibrational convection". The effect of vibrations changes qualitatively, and their effectiveness increases significantly under conditions of rotation. This makes vibrations an important tool for controlling the dynamics of non-isothermal systems and the intensification of heat and mass transfer in rotating cavities, which could be useful for optimization of various technological processes. The article describes methods used to study convection in rotating cylinders subject to vibrations. The cases of an annulus with boundaries at different temperatures and a cylinder filled with a heat-generating fluid are discussed. Experimental complex allows one to study thermal convection under the action of various factors, such as rotation, vibrations, librations, orientation of the axis of rotation, inertial waves, and others. •The vibrations of a non-isothermal fluid in a rotating cavity is an effective tool for intensification of heat transport due to the generation of intensive averaged flows•The developed experimental technique and setup provide the investigation of thermal vibrational convection in rotating cavities of various geometries in a wide range of governing dimensionless parameters.