Aim
Our aim was to evaluate the efficacy of indocyanine green (ICG) fluorescence angiography (FA) in reducing the incidence of anastomotic leakage (AL) following colorectal anastomosis.
Method
A ...single‐centre randomized trial was undertaken between 2018 and 2019. Those patients who underwent a stapled colorectal anastomosis were randomized 1:1 for ICG FA versus visual clinical assessment of blood perfusion of the anastomosed colon and rectal stump (non‐ICG FA group). The primary end‐point was to assess whether ICG FA was associated with a reduction in the incidence of AL. Secondary outcomes were the rate of postoperative complications and change in the level of bowel resection.
Results
A total of 380 patients undergoing sigmoid and rectal resection were enrolled. After randomization, three patients were excluded. The results of 377 cases were available for analysis; 187 had ICG FA and 190 were in the non‐ICG FA group. ICG FA identified impaired blood perfusion of the colon in 36 (19%) cases. An AL (grade A, B or C) developed in 48 patients: 17 (9.1%) in the ICG FA group and 31 (16.3%) in the non‐ICG FA group (P = 0.04). ICG FA did not decrease the rate of AL of high anastomoses (9–15 cm from the anal verge), at 1.3% vs 4.6% in the non‐ICG FA group (P = 0.37). In contrast, a decrease in AL rate was found for low (4–8 cm) colorectal anastomoses (14.4% in ICG FA vs 25.7% in the non‐ICG FA group; P = 0.04).
Conclusion
ICG FA is associated with a reduction in AL following low anterior resection.
Analysis of long-term fishing and biological data has made it possible to determine the proportion of respawning individuals (the “remainder”) in populations of Atlantic salmon
Salmo salar
inhabiting ...large rivers of the Kola Peninsula. The contribution of respawning individuals to the dynamics of the Atlantic salmon population was assessed using the mathematical simulation model. It is shown that the model population becomes more resistant to fishing with increase in the “remainder” proportion; however, the influence of such individuals on the population dynamics is noticeable only when their relative number is more than 5% in the spawning population. The results of different model experiments are interpreted. The role of respawning salmons may be determined not so much by their quantitative contribution to the reproduction process as by the maintenance of the genetic diversity of the population within the reproductive strategy characteristic of the Atlantic salmon.
The two-phase slug flow, or the Taylor flow, is used in a variety of applications, including efficient heat transfer in pulsating heat pipes (PHPs). The heat transfer efficiency is due to the ...presence of liquid thin film surrounding the bubble and separating it from the hot wall. The thin film facilitates much faster heat dissipation by evaporation as compared with single-phase cooling. The thinness of the liquid film also creates significant difficulty for numerical simulation of Taylor bubbles, and the lower is the bubble velocity, the thinner is the liquid film. We carried out a 3D simulation of the hydrodynamics and heat transfer during motion of Taylor bubbles of gas in a capillary tube with a diameter of 2 mm in the velocity range of 0.05–0.5 m/s, resolving the near-wall region in detail. The distributions of the friction coefficient and heat flux on the wall along the bubble motion were obtained. It was shown that complex cascade recirculation zones appeared near the bubble and led to significant change in both shear stresses and heat flux near the wall as compared with a single-phase flow.
In this review, we consider the current state of development of both low-temperature superconductors based on Nb
3
Sn and high-temperature superconductors. The effect of the preparation method and ...the composition of alloying elements on the microstructure of the superconducting layer and the current-carrying capacity of superconductors based on Nb
3
Sn and high-temperature superconductors of the second generation based on yttrium and bismuth cuprates, magnesium diboride, and iron-containing compounds is analyzed.
Developing of laboratories on a chip or
μ
TAS (micro-total analysis systems) is a great challenge of the modern microfluidics. With the help of such devices, it will be possible to conduct many ...chemical analyses of human liquids for the preliminary diagnosis of various diseases. Despite the great importance of this task and certain successes in the field of experimental study of the behavior of the electrolyte in micro-devices, there are many undescribed effects, which opens up the possibility for a theoretical study of these processes. Usually, the flat geometry of devices is used in design of laboratories on a chip, which is explained by the simplicity of manufacturing, but our research shows that using the spherical geometry of the device allows to design a universal device that can work as a micro-pump, micromixer and micro-concentrator. The paper presents a theoretical analysis of the concentration effects of ions in a micro-device with presence of the pressure driven flow. The device presents a spherical chamber in the center of which an ion-selective microgranule is placed. This device is built into a circular channel through which the electrolyte flows due to the electroosmotic flow caused by the difference in electrical potentials. Depending on the orientation of the inlet channel relative to gravity, there is an additional pressure of the water column in the inlet or outlet channel. As a result of selection of a suitable external electric field, it is possible to achieve a significant concentration of ions near the ion-selective microgranule. The enriched region can be carried away by the convective flow far into the outlet channel and then this device can be used to separate the flow into enriched and depleted, as happens with electrodialysis. The efficiency of the device increases with an increase in the intensity of the external field, however, starting from a certain critical value of the electric field strength, the steady state flow loses stability and an electroconvection is formed, which interferes with the concentration process. Due to the additional pressure, both the stability of the flow and the degree of concentration can be adjusted. The paper shows that by varying the values of the field strength and pressure gradient, it is possible to achieve maximum efficiency of the device.
Issues related to the lack of convergence in the application of formally path-conservative difference schemes for solving nonconservative hyperbolic systems of equations are numerically investigated. ...This problem is central in constructing well-posed difference schemes for solving this class of problems. The basic concepts of the theory of nonconservative hyperbolic systems of equations and the corresponding problems of constructing difference schemes for their solution are outlined. A variant of the HLL method is proposed that allows using an arbitrary explicitly specified path. For a model system of Burgers equations, the shock adiabates and paths corresponding to the viscous regularization of a system of a given form are explicitly calculated. The reasons for the lack of convergence of numerical solutions of exact ones in the case of incorrect application of the corresponding algorithms are analyzed. It is shown that, at least in the particular case considered, a variant of the HLL method that is formally conservative along the way gives the correct solution of the problem.
We obtain a power series representation of the Weierstrass sigma function arising in the theory of elliptic functions and derive a differential–recurrence equation as well as closed-form expressions ...for its coefficients. These results are obtained using the Weierstrass system of partial differential equations satisfied by the sigma function.
Abstract
Numerical modeling of the outflow of an air jet into water with a guillotine rupture of a pipeline by the VOF method using k-ε and k-ω SST turbulence models was carried out. The calculations ...were carried out in the axisymmetric approximation. The following phases of the outflow process were calculated: the formation of a large gas bubble at the place of the rupture, its growth, the separation of the bubble from the place of rupture, and the formation of a gas jet behind the bubble. It is shown that the rate of bubble detachment in the calculations by the k-ω SST model is higher than that in the calculation by the k-ε model.
We propose a numerical method for solving problems of two-phase two-velocity hydrodynamics in the framework of the Baer–Nunziato model with relaxation. The model equations are solved using the ...discontinuous Galerkin method with the WENO-S limiter, which is applied directly to the conservative variables of the model. Relaxation processes are modeled using the second-order implicit Runge–Kutta method with an adaptive choice of the integration step. The algorithm includes the Newton method for solving the equations of the nonlinear Runge–Kutta method. The corresponding Jacobi matrices are calculated using numerical differentiation. We present the results of numerical calculations that demonstrate the capabilities of our algorithm. The results of numerical calculations are compared with the analytical solution as well as with the results obtained by other authors. The results of numerical experiments with different relaxation rates are presented, including the case of “stiff” relaxation.
Abstract
Gas outflow into a cavity with different annular assembly filled with liquid by the VOF method, supplemented by the k-ε turbulence model, is numerically simulated. Calculations are performed ...for three types of ring assembly. Principal scenarios of bubble growth outside the assembly and annular jets inside it are obtained. The characteristic expiration times are investigated.
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