Film Rupture Research Articles

Role of hydrophobic fine particles in coarse particle flotation: An analysis of bubble-particle attachment and detachment

It is widely accepted that hydrophobic fine particles improve froth stability and thus increase the recovery of coarse particles in the froth phase. In fact, the presence of fine particles also enhances coarse particle recovery in the collection zone. It is not yet known what causes this, nor is it known how fine particles affect interactions between bubbles and coarse particles (collision, attachment, and detachment). In the present study, the role of hydrophobic fine particles in improving the recovery of coarse particles in the pulp phase was discussed from the perspective of bubble-particle interaction. Flotation tests of coarse particles with different fine particle contents were first carried out. The bubble collision-attachment test, bubble-particle aggregate stability test, and interaction force test were used to further explain the effects of fine particle coverage on bubble-particle interactions. The results show that the recovery of coarse particles increases as the fine particle content in the flotation feed increases. Although the presence of hydrophobic fine particles prevents the rupture of the liquid film and the formation of the contact line between bubble and coarse particle, it can also greatly increase contact angle hysteresis, increasing the maximum force required to pull coarse particle from the gas-liquid interface into the aqueous phase. Furthermore, the coverage of fine particles helps to improve the energy dissipation during the bubble collision and reduce the oscillation of the bubble-particle aggregates. As a result, the increase in coarse particle recovery in the presence of fine particles is due to the decrease in the detachment of the bubble-particle aggregate. The important findings of this study are expected to provide a basis for understanding the interaction between multiple particles and bubbles in actual flotation.

Observation of the microstructure of a bi-extended hydrated dough and hydrated gluten under large strain and extremely low strain-rates: Results of an initial study

A small bubble-inflation device was developed for use in conjunction with a Low-to-Mid Range Magnification Digital Microscope. This device made it possible to observe the bi-extension of dough and gluten films at the top of a bubble under conditions that mimicked as closely as possible the typical GCW thicknesses, strains, strain rates and gaseous ambience found in dough during everyday proving or baking. For this stage, experiments were carried out at 20 °C. Stress-strain relationships were measured at strain rates ranging from 0.0006 to 0.09 s−1. The reduction in size yielded higher stress measurements compared to the results obtained from usual inflation devices (Alveograph®). Strain hardening in dough and hydrated gluten was observed regardless of the strain rate applied. A first trial using image analysis of the top of the bubble during deformation revealed useful information on the locations of the dough constituents and made it possible to reevaluate strain and strain-rate. The Hencky strain and stress at rupture were found to be of the order of 1.23 and 50–100 kPa respectively. This work illustrates the potential benefits of linking image analysis to a bubble-inflation device for the analysis of the mechanisms involved in the mechanical rupture of dough films.

Stress corrosion inhibition mechanism of hot rolled medium thickness Al–Zn–Mg–Cu plate by cryogenic-aging treatment

In this article, a novel cryogenic-aging treatment was realized by introducing the deep cryogenic treatment (DCT) in liquid nitrogen prior to artificial aging. The stress corrosion performance of the hot rolled medium thick Al–Zn–Mg–Cu plate after cryogenic-aging treatment was investigated by mechanical properties test, in-situ electrochemical test and microstructure analysis. It was found that the DCT-8 h and 24 h prior to double-stage aging treatment were optimum parameters. Cryogenic-aging treatment prolonged the duration of Al–Zn–Mg–Cu alloy under the coupling of stress and corrosion media. In addition, cryogenic-aging treatment promoted the multiplication of dislocations aggregated on the grain boundary or sub-grain boundary, which provided nucleation sites of precipitates and reduced the width of precipitates-free zone (PFZ). In-situ electrochemical test and microstructure observation were combined to analyze the inhibition mechanism of stress corrosion by cryogenic-aging treatment, which effectively inhibits the rupture of oxide film and the propagation of crack during the initial stage. This study proposes a simple and efficient process to enhance stress corrosion performance, which has important guidance for the application of Al–Zn–Mg–Cu alloys in the aerospace and transportation industries.

Instability and rupture of surfactant-laden bilayer thin liquid films.

The stability of surfactant-laden bilayer thin films, where the top layer is subject to van der Waals driven breakup, is of particular relevance to applications where one thin liquid layer is spread on another, such as film-forming firefighting foams and multilayer coatings. Although there has been much prior modeling work on the stability of thin liquid bilayers, additional physical effects and assumptions were incorporated in those studies, making it difficult to isolate the influence of surfactant on the rupture of the top layer. The present work addresses this issue through application of the lubrication approximation to derive a coupled system of nonlinear evolution equations describing the perturbations to the liquid-liquid and liquid-air interfaces and the surfactant interfacial concentrations. The surfactant is assumed to be insoluble and can be present at each interface. Linear stability analysis suggests, and nonlinear simulations confirm, that by using surfactant that adsorbs to both interfaces, the rupture time can be increased by an order of magnitude relative to the surfactant-free case. However, we find it crucial to have the right amount of surfactant to generate strongly stabilizing Marangoni stresses without reducing the interfacial tension too much. Nonlinear simulations and linear stability analysis provide insight into the mechanisms of the delayed rupture and show how the direction and strength of the Marangoni stresses strongly depend on the viscosity ratio of the layers. These results can help guide the choice and design of surfactants to achieve more effective firefighting foams and more stable liquid coatings.

Investigation on the pitting corrosion properties of welded joints of bimetal composite pipe

A bimetallic composite pipe butt joint was prepared by automatic gas tungsten arc welding (GTAW). The microstructure and pitting properties of the joint were investigated. The results show that the microstructure of the joint is columnar crystal, columnar dendrite, and equiaxial crystal. Mo, Nb, and Cr segregate in joint and form Laves and NbC precipitates in the interdendritic. The heat-affected zone (HAZ) becomes the preferred region for pitting due to recrystallization behavior and large and continuous Laves, this was demonstrated by both immersion corrosion and electrochemical experiments. To better understand the pitting behavior of the joint, this study discusses the mechanism of passive film rupture and pitting development, and uses electrolytic corrosion by Nital to simulate the morphology of the initial corrosion pits around the Laves phase.

A review on pitting corrosion and environmentally assisted cracking on duplex stainless steel

Duplex stainless steel is widely used in the petrochemical, maritime, and food industries. However, duplex stainless steel has the problem of corrosion failures during use. This topic has not been comprehensively and academically reviewed. These factors motivate the authors to review the developments in the corrosion research of duplex stainless steel. The review found that the primary reasons for the failure of duplex stainless steels are pitting corrosion and chloride-induced stress corrosion cracking. After being submerged in water, the evolution of the passive film on the duplex stainless steel can be loosely classified into three stages: nucleation, rapid growth, and stable growth stages. Instead of dramatic rupture, the passive film rupture process is a continuous metal oxidation process. Environmental factors scarcely affect the double-layer structure of the passive film, but they affect the film's overall thickness, oxide ratio, and defect concentration. The six mechanisms of alloying elements on pitting corrosion are summarized as stabilization, ineffective, soluble precipitates, soluble inclusions, insoluble inclusions, and wrapping mechanisms. In environments containing chlorides, ferrite undergoes pitting corrosion more easily than austenite. However, the pitting corrosion resistance reverses when sufficiently large deformation is used. The mechanisms of pitting corrosion induced by precipitates include the Cr-depletion, microgalvanic, and high-stress field theories. Chloride-induced cracks always initiate in the corrosion pits and blunt when encountering austenite. Phase boundaries are both strong hydrogen traps and rapid hydrogen diffusion pathways during hydrogen-induced stress cracking.

Evaluating the Efficacy of Polyglycolic Acid-Loading Tetrandrine Nanoparticles in the Treatment of Dry Eye

Introduction: Dry eye disease (DED) is a multifactor-induced disease accompanied by increased osmolarity of the tear film and inflammation of the ocular surface. Traditional anti-inflammation agent corticosteroids applied in DED treatment could result in high intraocular pressure, especially in long-term treatment. Therefore, we explored a nano drug that aimed to block the formation pathway of DED which had anti-inflammatory, sustained release, and good biocompatibility characteristics in this study. Methods: We prepared a novel nanomedicine (Tet-ATS@PLGA) by the thin film dispersion-hydration ultrasonic method and detected its nanostructure, particle size, and zeta potential. Flow cytometry was used to detect the cell survival rate of each group after 24 h of drug treatment on inflammed Statens Seruminstitut Rabbit Corneal (SIRC) cells. Observed and recorded corneal epithelial staining, tear film rupture time, and Schirmer test to detect tear secretion on the ocular surface of rabbits. The corneal epithelial thickness, morphology, and number of bulbar conjunctival goblet cells were recorded by H&E staining. Finally, we detected the expression of VEGF, IL-1β, PGE2, and TNF-α by cellular immunofluorescence staining and enzyme-linked immunosorbent assay (ELISA). Results: The encapsulation efficiency and drug loading of Tet-ATS@PLGA were 79.85% and 32.47%, respectively. At eye surface temperature, Tet can easily release from Tet-ATS@PLGA while that it was difficult to release at storage temperature and room temperature. After 2 weeks medication, Tet-ATS@PLGA can effectively improve the tear film rupture time and tear secretion time in a DED model (p <0.05). Compared with the normal group (62.34 ± 4.86 mm), the thickness of corneal epithelium in ATS (29.47 ± 3.21 mm), Tet-ATS (46.23 ± 2.87 mm), and Tet-ATS@PLGA (55.76 ± 3.95 mm) gradually increased. Furthermore, the flow cytometry indicated that Tet-ATS@PLGA can effectively promote the apoptosis of inflammatory SIRC cells, and the cellular immunofluorescence and ELISA experiments showed that the expression intensity of inflammatory factors such as VEGF, IL-1β, PGE2, and TNF-α decreased in this process. Interestingly, Tet also had the effect of reducing intraocular pressure. Conclusion: Tet-ATS@PLGA can effectively promote the apoptosis of inflammatory corneal epithelial cells, thus inhibiting the expression of inflammatory factors to block the formation of DED and improve the secretion of tear on the ocular surface.

Effect of surfactant on the attachment between coal particles and bubbles: An experimental and molecular dynamics simulation study

Surfactant plays a vital role in flotation, especially in the adsorption of particle and bubble surface. From macroscopic to atomic scales, the effects of surfactant on the attachment between coal particles and bubbles were investigated by the induction time measurements, bubble-particle wrap angle measurements, thin liquid films measurements and molecular dynamics (MD) simulation. The three surfactants are Cetyltrimethylammonium bromide (CTAB), Sodium dodecylbenzene sulfonate (SDBS), and Methyl isobutyl carbinol (MIBC). Macroscopically, the coal particles could be more easily attached to a bubble surface in three solutions, particularly in CTAB solution. This was because the speed of thinning and rupture of thin liquid film between coal-particles and bubbles was faster in CTAB solution than that in other solutions. MD simulation findings show that the adsorption of CTAB significantly improves the water molecule migration rate. In addition, the CTAB promotes the attachment efficiency in floatation.

Effect of aging temperature on thermal stability of lithium-ion batteries: Part A – High-temperature aging

Aging and thermal runaway are two significant reasons why lithium-ion batteries are struggling to become more widely available. Aging at different temperatures causes differences in the aging mechanism and thermal runaway behaviour of lithium-ion batteries. In this paper, four sets of commercial lithium-ion batteries are aged at 25 °C, 40 °C, 60 °C and 80 °C respectively for 100 cycles. Then the morphology and composition of the electrodes and separators are analysed in order to reveal the mechanism of changes in electrical performance and thermal stability due to aging at different temperatures. The differences in the decomposition products of the solid electrolyte intermediate (SEI) layer are an important factor in inducing changes in thermal runaway behaviour. At 60 °C, the accumulation of SEI decomposition products results in thicker SEI layers and shorter thermal runaway times. At 80 °C, the SEI decomposition products are heavily transformed into particles with a loose structure, generating a large amount of gas in the process, which further leads to the rupture of the aluminium-plastic film and the evaporation of the electrolyte, with a longer duration of thermal runaway and a lower maximum temperature.

Theoretical and experimental study on drag torque of wet clutch considering surface tension and shrinkage of oil film

The drag torque produced by the viscous shearing action of lubricating oil is an important component of the power loss of wet clutches. Studying the prediction model and its influencing factors will provide important theoretical support for reducing the drag torque. Taking a single friction pair wet clutch as the research object, this research obtained the oil film shrinkage under different working conditions based on the VOF model. On this basis, a drag torque calculation model considering the surface tension and shrinkage of oil film is established, in which the drag torque is composed of the torque transmitted by oil film in the oil film continuous zone and the torque transmitted by oil-liquid and gas-liquid in the oil film rupture area, respectively. Comparing the theoretical drag torque with the simulation and experimental results, the variation law of drag torque with the speed difference under different oil film thicknesses and different supply flow is obtained, and the validity of the theoretical model is also verified. Results show that increasing the oil film thickness and decreasing the supply flow will lead to a decrease in drag torque, which provides a useful reference for reducing the drag torque.

The Influence of the Surface Chemistry of Cellulose Nanocrystals on Ethyl Lauroyl Arginate Foam Stability.

Guanidine-based surfactant ethyl lauroyl arginate (LAE) and cellulose nanocrystals (CNCs) form complexes of enhanced surface activity when compared to pure surfactants. The LAE-CNC mixtures show enhanced foaming properties. The dynamic thin-film balance technique (DTFB) was used to study the morphology, drainage and rupture of LAE-CNC thin liquid films under constant driving pressure. A total of three concentrations of surfactant and the corresponding mixtures of LAE with sulfated (sCNC) and carboxylated (cCNC) cellulose nanocrystals were studied. The sCNC and cCNC suspension with LAE formed thin films, with stability increasing with surfactant concentration and with complex rheological properties. In the presence of LAE, the aggregation of CNC was observed. While the sCNC aggregates were preferentially present in the film volume with a small fraction at the surface, the cCNC aggregates, due to their higher hydrophobicity, were preferentially located at film interfaces, forming compact layers. The presence of both types of aggregates decreased the stability of the thin liquid film compared to the one for the LAE solution with the same concentration. The addition of CNC to LAE was critical for foam formation, and foam stability was in qualitative agreement with the thin films' lifetimes. The foam volume increased with the LAE concentration. However, there was an optimum surfactant concentration to achieve stable foam. In particular, the very resistant foam was obtained with cCNC suspensions that formed the interfaces with a complex structure and rheology. On the other hand, at high LAE concentrations, the aggregates of CNC may exhibit antifoaming properties.

Unraveling the passive film formation and degradation mechanism of NiTi shape memory alloy: An experimental investigation

TiO 2 passive film plays an important role in defining biocompatibility of NiTi shape memory alloy. The corrosion behaviour of Ni 50.8 Ti 49.2 was investigated in 0.9 wt.% aqueous NaCl solution. Grazing incident X-ray diffraction (GIXRD) reveals the formation of a compressive passive film having 2.12% d-spacing variation, noticeably in B19’ structure. The surface topography (undulation) and passive film thickness was recorded in a unique way using atomic force microscopy (AFM). Raman spectrometer and X-ray photoelectron spectroscopy (XPS) investigation confirm the formation of TiO 2 -dominated passive film. Film rupture and breakdown initiation sites were precisely captured by field emission scanning electron microscope (FESEM).

Investigation of the film-forming ability of proteins subjected to UV treatment for the dairy industry development

Film-forming mixtures based on reconstituted solutions of whey protein concentrates (WPC) with a protein content of 2.0 and 5.0% were subjected to UV irradiation in the range from 90 to 150 J/ml. With an increase in the dose of UV irradiation in film-forming solutions, the solubility of the protein decreased, the greatest effect was achieved in a mixture with a protein content of 2.0%. The decrease in solubility indirectly proved the process of aggregation of protein molecules in the studied solutions. It has been shown that UV exposure improves the strength properties of protein films. The highest specific stress at film rupture at an irradiation dose of 150 J/ml was 23.11 MPa in a 5.0% protein solution and 5.74 MPa in a 2.0% solution. The indicator of the applied force increased more intensively when processing a 5.0% protein solution, and amounted to 16.00 N in the case of a 2.0% solution, and 24.82 N in a 5.0% solution.

Experimental study of dewetting instability in polymer multilayer shear flow

<h2>Abstract</h2> The interfacial stability of multilayer Couette flow is investigated experimentally. A better understanding of this flow is critical for the processing of multilayer polymeric structures, such as multilayer coextrusion. We first look at the liquid film rupture predictions from numerical simulations of the thin film equation that considers capillary and van der Waals forces. With the addition of shear, three regimes have then been evidenced as a function of the shear rate. In the regime of low shear rates the rupture is delayed when compared to the no-shear problem, while at higher shear rates it is suppressed. Then, experiments investigating the effect of shear on the dewetting of thin polymer films at different temperatures by using an optical microscope coupled with a shearing hotstage will be presented. The dewetting dynamics, i.e. the growth of dewetting holes is monitored over time at various shear rates. It is observed that their circularity is modified by shear and that for all temperatures and thicknesses studied, the growth speed of the formed holes rapidly increases with increasing shear rate. A model balancing capillary forces and viscous dissipation while taking into account shear-thinning is then proposed and captures the main features of the experimental data, such as the ellipsoid shape of the holes and the faster dynamics in the direction parallel to the shear.

Tear film stability in dry eye syndrome: Time and break‐up patterns

AbstractPurpose: Comparison between traditional invasive methodologies and modern non‐invasive high‐tech methodologies for qualitative and quantitative evaluation in 3 groups of patients with dry eye disease.Methods: Cross sectional study of 111 participants recruited consecutively at the eye clinic of San Giuseppe Hospital in Milan in 3 groups: healthy (n = 30), aqueous deficient dry eye ADDE) (n = 32) and evaporative dry eye (EDE) (n = 49) underwent osmolarity assessment, OSDI questionnaire, tear meniscus height measurement (TMH), Non‐invasive (NIKBUT‐first and NIKBUT‐average) and invasive (FBUT with fluorescein) tear film break up time, Meiboscore, corneal staining and Schirmer test.Results: FBUT, Schirmer test, f‐NIKBUT and a‐NIKBUT were significantly different between the three groups (p &lt; 0.001). FBUT and also f‐NIKBUT were lower in EDE group (4.46 ± 2.24) than other groups; In healthy and ADDE subjects, tear film break‐up time was located in the lower sector between the periphery average and the extreme. NiKBUT pattern was significantly different between the upper and lower peripheral, nasal and temporal periphery and the central temporal into the different groups (p &lt; 0.05). Correlation analysis showed an inverse association between age and f‐NIKBUT (r = −0.358) between all patients. Corneal staining was more severe in ADDE patients.Conclusions: In ADDE group the f‐NIKBUT was higher, almost at normal values, compared to FBUT. In a previous study, NIKBUT was found to be higher than FBUT due to non‐installation of dyes in the eye. In healthy and EDE subjects the tear film rupture was located in the lower sector between the average periphery and the extreme, probably due to a longer exposure time than in other areas. In EDE subjects, however, f‐NIKBUT was found in the central temporal and nasal sectors in according with previous studies. Average and f‐NIKBUT were negatively related with the age and also positively related to each other. FBUT and f‐NIKBUT were related to each other differently in 3 groups of patients; they could study different aspects of the same phenomenon, further studies are ongoing.

Effect of sodium hyaluronate eye drops combined with tobramycin, dexamethasone and pranoprofen eye drops in the treatment of dry eye after phacoemulsification.

To investigate the clinical effect of sodium hyaluronate eye drops combined with tobramycin, dexamethasone, and pranoprofen eye drops in the treatment of dry eye after phacoemulsification. Medical records of 188 patients with dry eye after phacoemulsification, treated in our hospital from August 2020 to August 2021, were included and divided into groups based on the type of dry eye treatment. Patients in the control group (n = 90) were treated with tobramycin, dexamethasone, and pranoprofen eye drops. Patients in the test group (n = 98) were treated with sodium hyaluronate, tobramycin, dexamethasone, and pranoprofen eye drops. The tear secretion test (TST), film rupture time (BUT), corneal fluorescence staining (FS) score, levels of interleukin (IL)-6, and tumor necrosis factor (TNF)-α before the treatment and at 1 month follow-up, the overall total effective rate and the number of completely cured cases were compared between the two groups. Multiple linear regression was used to calculate coefficients for predicting clinical variables. Ordinal logistic regression was used to compute coefficients and odds ratios for predicting effective scores. The total effective rate in the observation group (99%) was significantly higher than that in the control group (80.00%). After the treatment, the TST and BUT indexes of the observation group were higher compared to the control group, and the FS score of the observation group was lower than that of the control group. TNF-α and IL-6 levels of the observation group were lower compared to the control group. Logistic regression analysis demonstrated that the differences in the effective rate and clinical variables between the two groups remained significant after adjusting for the effect of age. A combination of sodium hyaluronate, tobramycin, dexamethasone, and pranoprofen eye drops for the treatment of dry eye after phacoemulsification can improve the curative effect, reduce corneal fluorescein staining and inflammatory factor index levels compared to the treatment regimen lacking sodium hyaluronate eye drops.

Thermally driven Marangoni effects on the spreading dynamics of droplets

The influence of the thermally-induced Marangoni stresses on the falling and spreading dynamics of a droplet surrounded by another liquid phase is numerically studied. A water droplet is released in a three-dimensional (3D) domain filled with oil. The droplet descends, comes at an apparent resting position above an oil film close to the bottom surface, and eventually wets the solid surface when the underneath film ruptures. A linear vertical temperature gradient is applied in the solution domain (with the bottom surface as the cold side) which imposes a surface tension gradient across the oil-water interface. The Marangoni source term is added to the momentum equation coupling the momentum and the energy equations. It is assumed that the dynamic contact angle changes according to the Kistler relation during the spreading. The Volume of Fluid (VOF) method is used to capture the interface between the phases. The solver is validated for both the falling and spreading phases. During the buoyancy-driven falling regime, the droplet retains its spherical shape at the low Reynolds number O(1) and finite Bond number O(0.001). It is revealed that the spreading rate of the droplet is a decreasing function of Marangoni number (Ma). Unlike the isothermal systems, where the bottom side of the droplet becomes slightly flattened at the resting stage, the Marangoni stress imposes an upward force on the droplet which elongates the shape of droplet in the temperature gradient direction. Consequently, the ultimate spreading radius at the equilibrium state is smaller at larger Ma. The slow rate of spreading and also the small wetted area at large temperature gradients adversely affect the heat transfer rate from the liquid to the cold plate where the local convective heat transfer coefficient and the average Nusselt number (Nu) are decreasing functions of the Marangoni stress.

Acupuncture Alleviates Corneal Inflammation in New Zealand White Rabbits with Dry Eye Diseases by Regulating α7nAChR and NF-κB Signaling Pathway.

The purpose of this study is to determine the mechanism of improvement in dry eye diseases (DEDs) treated by acupuncture. The inflammatory molecules and related pathways will be analyzed in our study. In order to establish the animal model for DEDs, healthy New Zealand white rabbits were treated with scopolamine (Scop) hydrobromide for 21 consecutive days. After 21 days, acupuncture, fluorometholone (Flu), and α7nAChR antagonist (α-BGT) treatments were performed, and the Scop injections were continued until day 35. The therapeutic effect of acupuncture on DED inflammation was evaluated by corneal fluorescence staining, tear film rupture time, tear flow measurement, in vivo confocal microscopy (IVCM), corneal histopathology, and cytokine protein chip technology. The influence of acupuncture on the corneal pathology and inflammatory factors ACh, α7nAChR, and NF-κB was detected by enzyme-linked immunosorbent assay (ELISA) and western blot. Compared with the group Scop, acupuncture can significantly reduce corneal staining and increase the tear film rupture time and tear flow, which are accompanied by a decrease in corneal epithelial detachment and lymphocyte infiltration. Acupuncture can relieve the inflammation of corneal stroma and mitigate the expression of proinflammatory factors and chemokines. Acupuncture can upregulate the expression of ACh and α7nAChR and downregulate the expression of NF-κB. Our findings demonstrate that acupuncture can alleviate corneal inflammation in New Zealand white rabbits with DEDs via α7nAChR and NF-κB signaling pathway regulation. The expression indicates that α7nAChR/NF-κB signaling pathway may be active and that acupuncture is a potential therapeutic target for dry eye.

Особенности лечения синдрома «сухого глаза» у пациентов с хроническим периферическим увеитом

Introduction. The development of inflammation and violations of the homeostasis of the tear film are of fundamental importance for the occurrence of dry eye disease (DED). In 28–57 % of cases, intermediate uveitis (IU) is accompanied by signs of irritation of the ocular surface and symptoms characteristic of DED. Purpose. Analysis of the effectiveness of complex treatment of DED and IU, including tear replacement and anti-inflammatory therapy in combination with laser retinal coagulation at the extreme periphery of the fundus. Material and methods. The results of treatment of 98 patients were analyzed: the main group – 78 patients – were prescribed complex treatment of DED, the comparison group – 20 patients – only local tear replacement and anti-inflammatory therapy. Evaluation of the effectiveness of the developed method of treatment of combined pathology was carried out after 3 and 6 months. based on the dynamics of OSDI indices, hyperemia of the bulbar conjunctiva, LIPCOF test and Norn test. Results. The use of complex treatment of DED in patients with IU contributes to a statistically significant (p &lt; 0.05) decrease in signs of discomfort according to the results of OSDI to 34.8 %, a decrease in the bulbar conjunctiva hyperemia index to 51.4 %, a decrease in the LIPCOF test index to 22.2 %, an increase in tear film rupture time to 23.3 % with stable CP relief for 6 months observations. Conclusions. Thus, the results obtained clearly demonstrate the effectiveness of the use of complex treatment of DED in patients with IU. The developed method contributes not only to increasing the stability of the tear film, but also to reducing subjective feelings of discomfort and ensuring relief of inflammation at the extreme periphery, which allows us to recommend its wide application. Keywords: dry eye disease, intermediate uveitis, laser coagulation of the extreme periphery of the retina

Annular liquid film thermohydraulic and intermittent dryout in microchannel flow boiling

The annular flow regime in microchannels is commonly described as the steady flow of a vapor core with a surrounding liquid film along the channel length. However, limited studies have suggested temporal discontinuity in the liquid film coverage of the microchannel wall. The lack of experimental tools to directly interrogate the liquid flow characteristics and the local surface heat flux has resulted in proliferation of different hypotheses concerning the physics of this process. Surface de-wetting due to high shear stresses at the vapor–liquid interface and liquid film instability and rupture due to perturbation growth at the vapor–liquid interface have been suggested as the underlaying causes of this phenomenon. In this study, a recently developed microsensor array capable of measuring the surface local heat flux and liquid film thickness and velocity is utilized to decipher thermohydraulic characteristics of the annular flow regime and intermittent dryout with unprecedented details. The studies are conducted in a 600 μm square cross-section microchannel using FC-72 as the test fluid at 70–80% exit vapor quality. The results show that liquid film thinning because of evaporation rather than de-wetting and film rupture is responsible for intermittent surface dryout. Studies at different mass and heat fluxes suggest that for a given surface heat flux, there is a mass flux threshold above which intermittent surface dryout vanishes. Furthermore, the experimental liquid and vapor flow velocities and liquid film thickness are used to calculate the liquid–vapor interfacial shear stress. The results suggest that under the studied conditions, the liquid–vapor interfacial shear stress has little impact on the surface intermittent dryout. This study enhances predictable and reliable design and operation of two-phase heat sinks at high exit vapor qualities.