Dendritic Pattern Formation and Contact Line Forces during Dewetting of Dilute Polymer Solutions on a Hydrophobic Surface

The micro-scale morphology of the receding contact line of dilute polyethylene oxide solution drops (c ∼ 100 ppm) after impact and inertial spreading on a fluorinated hydrophobic surface is investigated. One can observe the formation of transient liquid filaments and dendritic structures that evolve into a bead-on-a-string structure similar to the well-known capillary breakup mechanism of dilute polymer solutions, which confirm the interaction between stetched polymer coils and the receding three-phase contact line. The estimation of the average polymer force per unit contact line lenght provides a quantitative explanation for the reduction of the contact line retraction velocity reduction observed experimentally.

Solvability of a moving contact-line problem with interface formation for an incompressible viscous fluid

We investigate the free-boundary problem of a steadily advancing meniscus in a circular capillary tube. The problem is described using the “interface formation model,” which was originally introduced with the aim of avoiding the singularities that arise when classical hydrodynamics is applied to problems with a moving contact line. We prove the existence of an axially symmetric solution in weighted Hölder spaces for low meniscus speeds.

Molecular Origin of Fast Evaporation at the Solid–water–vapor Line in a Sessile Droplet

By analyzing the behaviors of water molecules at the solid–water–vapor contact line, we explore the molecular origins of large evaporation rates at the contact line and find new ways to...

Patterns of Gender-Based Violence in Conflict-Affected Ukraine: A Descriptive Analysis of Internally Displaced and Local Women Receiving Psychosocial Services

Since 2014, a protracted armed conflict has afflicted eastern Ukraine, resulting in the displacement of over 1.4 million residents. The resulting humanitarian crisis has placed women, particularly displaced women, at greater risk of gender-based violence (GBV). In Ukraine, reports of GBV were higher following the start of the conflict (22.4% in 2014 vs. 18.3% in 2007), with displaced women suffering from GBV nearly three times more than non-displaced residents (15.2% vs. 5.3%). Many GBV incidents in Ukraine have been reported along the “contact line,” the border separating government from non-government-controlled areas. This study compares types of GBV experienced by displaced and local (non-displaced) women receiving psychosocial support in order to identify the gaps in services during a time of conflict. Data was collected by mental healthcare providers from 11,826 women (25.5% displaced; 74.5% local) aged 15 to 69 receiving psychosocial services in five conflict-affected regions from February 2016 to June 2017. Group differences were assessed using Pearson’s chi-squared or Fisher’s exact tests for categorical variables and Wilcoxon rank-sum tests for continuous variables. Overall, almost half of the women experienced intimate partner violence and psychological abuse. Compared to residents, displaced women were more likely to report non-domestic GBV incidents involving sexual and economic violence. Almost 8% of violent incidents against displaced women occurred at checkpoints or at reception centers for internally displaced persons (IDP) and 20% were perpetrated by armed men. Consistent with the literature, this study suggests that displaced women are more vulnerable to attacks by persons outside the home and by armed groups. Our findings underscore the need to expand violence prevention programs to address the unique vulnerabilities of displaced women before, during, and after displacement. Programs should be tailored to prevent violence within and outside the home. Increased prevention efforts are needed in areas with high concentrations of armed men, along the contact line, and at IDP reception centers to protect displaced women. This is particularly urgent in the context of increased GBV due to COVID-19.

Increasing the contact line operational reliability by forecasting its constructive elements’ failures

The article discusses the issues of calculating the indicators of the power supply systems’ reliability. The analysis of the existing problem and options for its solution are given. To assess the patterns, the authors proposed a mathematical tool. The method based on the rectangular scores’ technique is adopted as a forecasting method. The development belongs to the class of specialized method-oriented software tools.

Verification of the gauss’s law with the unknown parameters by the Kolmogorov criterion in the problems of railways electric supply

Traction currents and voltages in the overhead railroad contact line hypothetically obey the Gauss’s distribution law. An algorithm for statistical modeling of the Kolmogorov distribution for the unknown values of the Gaussian law parameters has been developed. For a large number of the modeling program implementations, it has been shown that testing the hypothesis about the distribution law without taking into account the number of unknown parameters leads to an unacceptable increase in the criterion significance and a decrease in its power. The distribution of the Kolmogorov criterion is calculated with sufficient accuracy for two unknown parameters, which allows its wide practical use.

Modeling and calculation of SC currents for alternative group grounding system for the dc contact line supports

The problem of creating a mathematical model of the group grounding system of the contact line supports is considered. The paper considers an alternative way of organizing group grounding. For such a method of grounding, a model of a section of a DC railroad is proposed, which makes it possible to calculate the SC current. An analysis of the constructed model quality is carried out, an assessment of the calculation error according to the proposed method is given.

Contact line dynamics on a substrate coated with a fluoropolymer

This work investigates the dynamics of the contact line during the propagation of a dry spot in a water layer on a solid substrate. The substrate is coated with fluoropolymer by using a hot wire chemical vapor deposition method. The dry spot is generated using a thermocapillary mechanism caused by the heating of the substrate from below by the laser. By analyzing schlieren images, the dependence of the velocity of the contact line during the propagation of a dry spot was obtained for various initial thicknesses of liquid films.