Short Break-up Time Research Articles

A Possible Reciprocal Relationship Between Myopia and Dry Eye Disease in Japanese Teenagers.

To investigate the relationship between dry eye disease (DED) and myopia in Japanese teenagers. This clinic-based, retrospective, cross-sectional study assessed DED condition in 10- to 19-year-old teenagers presenting at Japanese eye clinics. They included 106 high myopic patients (HM; mean age, 16.4 ± 2.2 years), 494 mild myopic patients (15.0 ± 2.6 years) and 82 non-myopic teenagers (NM; 13.8 ± 2.6 years). Subjective refraction and anisometropia were measured. Myopia grade was classified as HM (≤ -6.00 D), MM (> -6.00 D, < -0.50 D), or NM (≥ -0.5 D). The presence of DED-related symptoms including dryness, irritation, pain, fatigue, blurring and photophobia were assessed through a questionnaire. Tear film break-up time (BUT) and fluorescein corneal staining were investigated. Comparison among three groups and regression analysis of myopic error and other variables were conducted. Anisometropia and astigmatic error were greatest in the HM group compared with the other groups (p < 0.001). The HM group reported less photophobia (p < 0.001) and less pain (p = 0.039) compared with the NM group. Regression analysis revealed that myopic error was correlated with astigmatic error (β = -0.231, p <0.001), anisometropia (β = -0.191, p <0.001), short BUT (β = -0.086, p = 0.028) and the presence of diagnosed DED (β = -0.112, p = 0.003). Dryness (β = -0.127 p = 0.004), photophobia (β = 0.117, p = 0.002) and pain (β = 0.084, p = 0.034) correlated with myopic error. This study associated clinical findings of DED in HM teenagers. The present results suggest DED might be associated with myopia, possibly in a reciprocal relationship.

Electroencephalogram-detected stress levels in the frontal lobe region of patients with dry eye

PurposeTo evaluate stress levels extracted from prefrontal electroencephalogram (EEG) signals and investigate their relationship with dry eye symptoms. MethodsThis prospective, cross-sectional, comparative study included 25 eyes of 25 patients with aqueous tear-deficient dry eye (low Schirmer group), 25 eyes of 25 patients with short tear breakup time dry eye (short breakup time group), and 24 eyes of 24 individuals without dry eye. An EEG test, the Japanese version of the Ocular Surface Disease Index (OSDI), and a stress questionnaire were administered. EEG-detected stress levels were assessed under three conditions: eyes closed, eyes open, and eyes open under ocular surface anesthesia. ResultsStress levels were significantly lower when the eyes were closed than when they were open in all groups (all P < 0.05). Stress levels during eyes open under ocular surface anesthesia were significantly lower than those during eyes open without anesthesia only in the low Schirmer group; no differences were found between the short breakup time and control groups. OSDI scores were associated with EEG-detected stress levels (P = 0.06) and vital staining score (P < 0.05) in the low Schirmer group; they were not associated with EEG-detected stress (P > 0.05), but with subjective stress questionnaire scores and breakup time values in the short breakup time group (P < 0.05). ConclusionsIn the low Schirmer group, peripheral nerve stimulation caused by ocular surface damage induced stress reactions in the frontal lobe, resulting in dry eye symptoms. Conversely, in the short breakup time group, the stress response in the frontal lobe was not related to symptom development.

The unique properties of tear film breakup process in patients with nasal unilateral pterygium.

This study found that the unique properties of tear film breakup process in eyes with pterygium, combined with ocular surface parameters, further revealed specific dynamic mechanism. It suggested that the thickness of pterygium was especially valuable in deciding the necessity of surgical management. This study aimed to explore the dynamic mechanism of tear film instability in eyes with pterygium. A paired-eye controlled cross-sectional study was conducted. Seventy-eight patients with nasal pterygium were enrolled. Fluorescein tear film breakup was observed. Several key parameters related to tear film quality were defined and analyzed, including total breakup area (mathematically derived from pixel size using MATLAB), breakup velocity, fluorescein breakup time, breakup location and pattern, tear meniscus height, score of fluorescein corneal staining, and meiboscore. With comparable tear meniscus height, score of fluorescein corneal staining, and meiboscore between paired eyes (p > 0.05), eyes with pterygium had shorter breakup time, larger breakup area, and faster breakup velocity (p < 0.05). In eyes with pterygium, a positive correlation between meiboscore and pterygium parameters including length, thickness, and size was observed (p > 0.001). As the thickness increased, difference of breakup time and area between paired eyes increased (p = 0.02 and 0.046). Eyes with pterygium had more fixed inferonasal breakup location and often presented as dimple break (60%), whereas random break was the most common in contralateral normal eyes (62%). A unique breakup pattern named pterygium-induced local dimple break was found. It displayed as an irregular but vertical line-like shape appearing after lipid layer spreading, which was adjacent to the lower margin of pterygium and presented with unique properties including inferonasal breakup location, local breakup area, shorten breakup time, and faster breakup velocity. Eyes with pterygium showed a unique tear film breakup process and novel breakup pattern named pterygium-induced local dimple break . Dynamic mechanism played a significant role in tear film instability of eyes with pterygium rather than aqueous deficiency and increased evaporation.

Numerical simulations of droplet evaporation and breakup effects on heterogeneous detonations

Evaporation and breakup of droplets are critical phenomena in the liquid-fueled, multiphase detonation process. Understanding the relevant conditions and times for each process is crucial for predicting real world behavior. In this paper, the effects of evaporation and breakup on the multiphase detonation process will be explored through Euler-Lagrange (EL) simulations. Various droplet sizes of n-dodecane (C12H26) are reacted with oxygen (O2) utilizing a single-step global reaction mechanism. Droplet processes are modeled using temperature dependent thermophysical properties through the liquid-gas phase change and into the supercritical regime. Two aerodynamic breakup models are considered (based on theorized hydrodynamic instability mechanisms) from both empirical and theoretical approaches. Detonation wave velocity deficits are observed to be sensitive to breakup and evaporation time. It is shown that droplets redistribute fuel vapor mass over their lifetime, perturbing the equivalence ratio and creating vapor rich regions that cannot fully react. It was shown that as the total evaporation time decreases (shorter breakup time), the detonation structure becomes more like the idealized gaseous detonation case.

Pulsed coaxial drop-on-demand electrohydrodynamic printing

This research demonstrates pulsed electrohydrodynamic drop-on-demand (DoD) printing as a novel technique for synthesizing core–shell microparticles in a controlled manner. In this regard, a multiphase and multiphysics model is presented for coaxial electrohydrodynamic printing. The governing partial differential equations of the model are discretized using the finite element method, and a suitable numerical scheme is adopted to solve the system of discretized equations. The experimental results in the literature are used to validate the numerical model. Utilizing the validated model, the effects of continuous-direct current (DC) voltage and pulsed-DC voltage are examined on the behavior of a compound meniscus (composed of ethylene glycol core and olive oil shell) and the droplet formation process. According to the results obtained, the onset voltage of the compound meniscus is 3330 V, which agrees with the scale analysis. Furthermore, increasing continuous-DC voltage results in longer breakup length, shorter breakup time, faster droplet velocity, and shorter jetting start time. In addition, increasing pulsed-DC voltage duration leads to an increase in the breakup length and droplet velocity. Most importantly, it is possible to control the inertia of the coaxial spindle by controlling the pulsed-DC voltage magnitude and duration to ensure that a core–shell droplet separates from the meniscus in every pulse with the shortest breakup length and the minimum satellite droplets possible. It is generally recommended to keep the pulse duration and amplitude low enough to prevent the long breakup length and irregularities in the printed pattern; however, they must be sufficiently large to sustain the micro-dripping mode.

Prevention of Surgery-Induced Dry Eye by Diquafosol Eyedrops after Femtosecond Laser-Assisted Cataract Surgery.

Purpose: To analyze the protective effects of diquafosol eyedrops on the ocular surface following femtosecond laser-assisted cataract surgery (FLACS). Design: A prospective, randomized contralateral study. Methods: Bilateral FLACS with a trifocal IOL (PanOptix) implantation was performed in 40 eyes in 20 patients (10 males, 10 females, average age 68.8 ± 6.3 years old). Patients received 3% diquafosol eyedrops six times daily in one randomly chosen eye (diquafosol group), and physiological saline six times a day in the other eye (control group). Other medication included 1.5% levofloxacin, 0.1% dexamethasone and 0.1% diclofenac three times daily in both eyes. The pre and post-operative tear break-up time (BUT), superficial punctate keratopathy (SPK) scores and visual function were compared between both eyes, and all patients answered the dry-eye-related quality of life score (DEQS) questionnaire. Results: The BUT between groups was similar pre-operatively and on the first day post-op; however, the BUT was statistically longer in the diquafosol group compared to saline at 1 week (5.5/3.7 s) and 2 weeks (4.8/3.0 s) (p < 0.05). There was no difference in the SPK score, best corrected distance visual acuity, tear meniscus height, contrast sensitivity, DEQS and Schirmer test at all time points. Spherical aberration was statistically lower in the diquafosol group at 1 week. The protective effects of diquafosol on the BUT was more pronounced in patients with a pre-operative BUT of less than 5 s compared with those with a BUT longer than 6 s. Conclusions: Diquafosol eyedrops prevented the shortening of the BUT following FLACS, even in patients with short pre-operative BUT values.

Effects of indoor low humidity on eye discomfort and associated physiological responses in soft contact lens and non-lens wearers

Eye discomfort due to dryness is one of the major complaints reported in indoor spaces. The purpose of this study was to quantitatively evaluate the effect of low humidity on eye discomfort in soft contact lens (SCL) and non-CL wearers. In addition to subjective sensations, physiological parameters related to eye discomfort including tear-film parameters and blink patterns were comparatively evaluated between relative humidities of 10% and 45% at 23°C. For both the SCL and non-CL wearer groups, low humidity had a significant effect on some of the measured physiological parameters. The SCL group showed lower ocular surface temperature and larger temperature differential after blinking at 10% relative humidity (RH) than that at 45% RH, indicating faster tear evaporation. Furthermore, their tear films tended to be thinner and have a shorter break-up time at 10% RH than at 45% RH. The non-CL group showed a significantly higher blink frequency and longer eye-closure time at 10% RH than at 45% RH, presumably as a compensatory response to the disturbance of the tear film due to low humidity. These results suggest the importance of humidity control in indoor spaces in terms of tear-film quality, which contributes to eye discomfort.

Short Tear Breakup Time Could Exacerbate the Progression of Presbyopia in Women.

Purpose The contributory factors and symptoms for presbyopia progression have not been fully determined. The purpose of the study was to compare presbyopia progression in subjects with short and normal tear breakup time and to explore the severity of common ocular symptoms associated with presbyopia progression. Method We conducted a clinic-based, retrospective, cross-sectional study. Inclusion criteria were bilateral phakic patients aged 40–69 years with best-corrected distance visual acuity better than 20/30, and exclusion criteria were the use of glaucoma eye drops, any disease affecting vision, or history of ocular surgery. We measured the binocular near add power and compared the results using Kaplan-Meier analysis. Association between near add power and ocular symptoms was explored. Results There were 1411 participants (mean age of 50.1 years). There were no significant differences in age, intraocular pressure, spherical equivalent, astigmatism, or anisometropia between the sexes. Kaplan-Meier analysis indicated that women with short tear breakup time reached the endpoint (near add power of +3.00 D) significantly earlier than those with normal tear breakup time (P = 0.043; Cox-Mantel test). Eye fatigue was most severe in the group with an add power of 1.25-2.00 D. Near add power was correlated with hyperopia, astigmatic errors, and anisometropia. Conclusions This study suggests an exacerbation of presbyopia progression in women with short tear breakup time. Eye fatigue was most severe in those with an add power of 1.25-2.00 D.

ELECTROHYDRODYNAMIC INSTABILITY OF A STREAMING DIELECTRIC VISCOUS LIQUID JET WITH MASS AND HEAT TRANSFER

The current paper investigates the electrohydrodynamic (EHD) instability of a streaming dielectric liquid jet. The inner medium is occupied by an incompressible Newtonian viscous fluid. Simultane-ously, the outer medium is filled with an incompressible gas. The system is pervaded by a uniform axial electrostatic field. The mass and heat transfer phenomenon is taken into account. In order to relax the mathematical manipulation, a simplified modulation of this system is adopted. The normal modes analysis is utilized to solve the boundary-value problem and to judge the linear stability of the system. A non-dimensional treatment reveals two non-dimensional numbers:Weber and Ohnesorge. The linear stability analysis resulted in a very complicated transcendental dispersion equation. The same numbers are considered with regard to the temporal and spatial increase of both frequency and modulation. The influences of various physical parameters in the stability profile are exercised as well. It is found that the velocity ratio between gas to liquid has a dual role in the stability profile. Moreover, the Weber number has a destabilizing effect, which produces a higher growth rate and, thus, shorter breakup time. In addition, the presence of the electric field as well as the mass and heat transfer stabilize the viscous liquid jet. Furthermore, the viscous effect as indicated by the Ohnesorge number has a stabilized influence. The present work gives a good foundation of the investigation of the instability and breakup of a viscous liquid jet with electric field effect and mass and heat transfer existence.

The proportion of ocular surface diseases in untreated patients with epiphora.

PurposeVarious ocular surface disorders, such as dry eye, infectious and non-infectious inflammation, anatomical anomalies in lid structure, and/or obstruction of the tear outflow tract, can cause epiphora. However, few reports have described the proportions of causative diseases in patients with epiphora. Therefore, we investigated the frequent causes of epiphora in older adult patients.Materials and methodsWe enrolled 220 patients (70 men, 150 women) who visited a primary eye care clinic from January 2016 to August 2017 with lacrimation as a chief complaint. The mean age of the patients was 61.3±10.9 years. The causes of epiphora were assessed by slit-lamp examinations, dry eye tests, fluorescein disappearance tests, and lacrimal pathway washing.ResultsThe causes of epiphora were dry eye in 96, conjunctivochalasis in 56, lacrimal obstruction in 30, conjunctivitis in 20, trichiasis in 16, and facial palsy in 2 patients. Ocular surface diseases were identified in 187 of the 220 (85%) patients who complained of epiphora. Conjunctivochalasis was observed in 36 of the 96 (38%) patients with dry eye. Among the patients with dry eye, 99% had short break-up time type dry eye, with the random break type being the most frequent type (61/96; 64%) in patients with epiphora.ConclusionAmong older adult patients whose main complaint was epiphora, 85% had ocular surface diseases. In contrast, only 15% of patients had lacrimal diseases. Short break-up time dry eye, especially the random break type, was the most frequently observed form of dry eye in our cohort.

Randomized Controlled Study to Investigate the Effect of Topical Diquafosol Tetrasodium on Corneal Sensitivity in Short Tear Break-Up Time Dry Eye.

Complex mechanisms underlie dry eye (DE) symptom provocation. In particular, corneal hypersensitivity may provoke symptoms in short tear break-up time (BUT) DE characterized by tear film instability. We hypothesized that improved tear film stability may alleviate corneal sensitivity in patients with short tear BUT DE. Therefore, we investigated the effect of topical diquafosol tetrasodium (DQS) on corneal sensitivity in unstable tear film DE. This prospective, randomized study included 27 subjects (age: 39.1 ± 8.4years; range: 25-59years) with short tear BUT DE, defined based on the presence of DE symptoms and tear film instability. Subjects were randomly divided into DQS (3% DQS, 12 subjects) and artificial tear (AT; preservative-free AT, 15 subjects) groups. Subjects applied the medication 6 times a day for 5weeks. The perception of touch (S-touch) and pain (S-pain) sensitivity was measured using a Cochet-Bonnet esthesiometer. Tear evaluation, corneal sensitivity, and DE symptoms were compared before and after DQS or AT administration. The correlation between the improvement degrees of corneal sensitivity and DE symptoms following medication was analyzed. DQS significantly improved tear BUT and tear meniscus height (TMH) scores (p < 0.05), while AT significantly improved tear BUT (p < 0.05) but not TMH score. Mean S-pain and DE symptom scores were lower after medication use in the DQS (S-pain and DE symptoms: p < 0.05) and AT groups (S-pain: p = 0.05; DE symptoms: p < 0.05). However, S-touch did not change significantly in either group. A positive correlation was observed between the improvement degrees of S-pain and DE symptoms in the overall subjects studied. Both DQS and AT alleviate corneal hypersensitivity and DE symptoms in eyes with short tear BUT DE. However, DQS seems to be more effective to adjust tear environment, leading to the normalization of corneal sensitivity and DE symptoms. UMIN Clinical Trials Registry Identifier, UMIN000014536.

Severe symptoms of short tear break-up time dry eye are associated with accommodative microfluctuations.

AimValidating the hypothesis that accommodative microfluctuations (AMFs) may be associated with severe symptoms in short tear break-up time (BUT) dry eye (DE).MethodsThis study included 12 subjects with short BUT DE (age: 49.6±18.3 years). Diagnoses were performed based on the presence of DE symptoms, BUT ≤5 s, Schirmer score >5 mm, and negative keratoconjunctival epithelial damage. Tear evaluation, AMF, and functional visual acuity (VA) examinations were conducted before and after DE treatment. The AMF parameters evaluated were: total high-frequency component (HFC), HFC with low accommodation for the task of staring into the distance (HFC1), HFC with high accommodation for deskwork (HFC2). A subjective questionnaire of DE symptoms was also performed.ResultsMean BUT increased from 1.9±2.0 to 6.4±2.5 s after treatment (P<0.05). The mean logarithm of the minimum angle of resolution functional VA significantly improved (from 0.19±0.19 to 0.12±0.17; P<0.05). Mean power spectrum values for total HFC and HFC1 decreased (from 61.3±5.7 to 53.8±6.6 dB and from 62.9±10.5 to 52.4±6.2 dB, respectively; P<0.05), while the mean HFC2 power spectrum values did not differ before and after treatment (P>0.05). Subjective DE symptoms were reduced in nine patients.ConclusionAlong with the improvement of BUT after treatment, DE symptoms diminished and HFC1 and functional VA improved, suggesting that tear film instability is associated with deterioration of functional VA, AMF, and DE symptoms.

Association Between Contact Lens Discomfort and Pre-lens Tear Film Kinetics.

The relationship between contact lens wettability and comfort has been extensively evaluated; however, a direct correlation between the characteristics of the pre-lens tear film and the symptoms associated with contact lens discomfort has yet to be established. In addition, there is relatively limited knowledge relating to the entire tear film kinetics during the inter-blink period in contact lens wearers. The purpose of this analysis was to identify the characteristics of the pre-lens tear film kinetics that may be associated with the symptoms of contact lens discomfort. The study population comprised 202 soft (hydrogel and silicone hydrogel) contact lens wearers attending pre-screening visits at the OTG-i research clinic. All participants completed the Ocular Surface Disease Index (OSDI) questionnaire and the tear film was quantified via post hoc, masked analysis of high definition digital Tearscope videos recorded at the visit. The tear film kinetics of the least symptomatic wearers (OSDI lowest quintile scores, n = 45) were compared to the tear film kinetics of the most symptomatic wearers (OSDI highest quintile scores, n = 43). The hypothesis tested was that the tear film kinetics of asymptomatic wearers were better than tear film kinetics of symptomatic wearers. The distribution of lens types worn was as follows: Daily Disposable 46.5%, 1-Month Replacement 39.6%, and 2-Week Replacement 13.6%. 48.2% of lenses were silicone hydrogel and 51.8% hydrogel. Symptomatic wearers had a shorter break-up time (4.7 s vs. 6.0 s; p = 0.003), lesser surface coverage by the tear film during the interblink period (95.1% vs. 98.5%; p < 0.001) and greater surface exposure at the time of the blink (9.4% vs. 3.9%; p = 0.001). The current study demonstrated that the tear film kinetics of asymptomatic and symptomatic contact lens wearers were different, the findings supporting the hypothesis of poorer tear film kinetics for symptomatic than asymptomatic wearers in a general contact lens wearing population.

Reducing Short-Wavelength Blue Light in Dry Eye Patients with Unstable Tear Film Improves Performance on Tests of Visual Acuity.

PurposeTo investigate whether suppression of blue light can improve visual function in patients with short tear break up time (BUT) dry eye (DE).MethodsTwenty-two patients with short BUT DE (10 men, 12 women; mean age, 32.4 ± 6.4 years; age range, 23–43 years) and 18 healthy controls (10 men, 8 women; mean age, 30.1 ± 7.4 years; age range, 20–49 years) underwent functional visual acuity (VA) examinations with and without wearing eyeglasses with 50% blue light blocked lenses. The functional VA parameters were starting VA, functional VA, and visual maintenance ratio.ResultsThe baseline mean values (logarithm of the minimum angle of resolution, logMAR) of functional VA and the visual maintenance ratio were significantly worse in the DE patients than in the controls (P < 0.05), while no significant difference was observed in the baseline starting VA (P > 0.05). The DE patients had significant improvement in mean functional VA and visual maintenance ratio while wearing the glasses (P < 0.05), while there were no significant changes with and without the glasses in the control group (P > 0.05),ConclusionsProtecting the eyes from short-wavelength blue light may help to ameliorate visual impairment associated with tear instability in patients with DE. This finding represents a new concept, which is that the blue light exposure might be harmful to visual function in patients with short BUT DE.

Relationship of Corneal Pain Sensitivity With Dry Eye Symptoms in Dry Eye With Short Tear Break-Up Time.

The purpose of this prospective comparative study was to investigate corneal sensitivity in subjects with unstable tear film, with and without dry eye (DE) symptoms. Forty-one eyes of 41 volunteers (mean age: 45.1 ± 9.4 years; age range, 23-57 years), with normal tear function and ocular surface except for tear stability, were studied. The eyes were divided into two groups depending on the presence or absence of DE symptoms: 21 eyes with DE symptoms (symptomatic group); and 20 eyes without DE symptoms (asymptomatic group). Three types of corneal sensitivity values were measured using a Cochet-Bonnet esthesiometer: the sensitivity for perception of touch (S-touch), the sensitivity for blinking (S-blink), and the sensitivity for pain (S-pain). Mean S-blink and S-pain were significantly higher in the symptomatic group than in the asymptomatic group (P < 0.05), whereas there was no significant difference in mean S-touch between these groups (P > 0.05). Corneal sensitivity for blinking and pain evoked by increased stimuli was higher in the symptomatic group (subjects with short break-up time DE) compared with subjects who have no DE symptoms despite decreased tear stability. The presence of both tear instability and hyperesthesia, rather than tear instability alone, may contribute to DE pathogenesis.

Short break-up time type dry eye has potential ocular surface abnormalities

PurposeTo describe a case series in which corneal fluorescein staining (CFS) development occurred in short break-up time (s-BUT) dry eyes after a short period during prolonged opening of the eye. MethodsThe study was designed as a clinical case series. Ocular surface evaluations were performed on 13 individuals with s-BUT dry eye. Tear function examinations included Schirmer's test and BUT evaluation. ResultsIn all 13 cases, the BUT was short, but the tear quantity was not so bad. In all cases, CFS developed following a single eye opening, and the staining was observed at sites that showed as dark spots. In several cases, the CFS disappeared later. ConclusionIn this study, we demonstrated that CFS could develop following a single eye opening. Based on our findings, CFS is a dynamic phenomenon rather than a stable indicator of ocular surface abnormalities. Moreover, s-BUT dry eye has the potential to show ocular surface abnormalities.

Effects of androgen on ultrastructure of corneal epithelium and function of the tear film in BALB/c mice.

The aim of this study was to investigate the effects of androgen on the ultrastructure of corneal epithelium and function of the tear film in a mouse model. Healthy adult male BALB/c mice were randomly apportioned to normal control, sham-operated, or orchiectomy groups. In the orchiectomy group, 4 subgroups with treatment [blank group, dihydrotestosterone (DHT) eye drop group, DHT injection group, and dimethyl sulfoxide (DMSO) eye drop group] were further established at 3 weeks after orchiectomy. Tear production, tear break-up time, and corneal fluorescein staining were evaluated in all groups at multiple time points. Serum androgen concentrations were measured by competitive radioimmunoassay, and ultrastructure of corneal epithelial cells was examined by transmission electron microscopy. Before orchiectomy, the mean serum concentration of androgen was 43.4 ng/μL, which decreased to approximately 0 ng/μL at 1 week after orchiectomy. Significantly less tear production, shorter tear break-up time, higher corneal fluorescein staining score, shorter and flattened corneal epithelial microvilli, and looser intercellular desmosomes were observed in mice after orchiectomy. DHT supplements increased serum androgen levels, and some of the tear film functions and morphological features of microvilli and desmosomes were gradually close to those at baseline in the DHT injection group. Persistent corneal staining, decreased tear production, short break-up time, and unhealthy corneal ultrastructure were observed in mice that received orchiectomy for at least 8 weeks. A mouse that received orchiectomy could be used as a dry eye model. Exogenous DHT supplement improved corneal epithelial ultrastructure and tear film function in this model.

Weakly nonlinear instability of planar viscoelastic sheets

A second-order weakly nonlinear analysis has been made of the temporal instability for the linear sinuous mode of two-dimensional planar viscoelastic liquid sheets moving in an inviscid gas. The convected Jeffreys models including the corotational Jeffreys model, Oldroyd A model, and the Oldroyd B model are considered as the rheology model of the viscoelastic fluid of the sheet. The solution for the second-order gas-to-liquid interface displacement has been derived, and the temporal evolution leading to the breakup has been shown. The second-order interface displacement of the linear sinuous mode is varicose, which causes the sheet to fragment into ligaments. First-order constitutive relations of the three rheology models become identical after linearization, so the linear instability results are also the same. For the second-order weakly nonlinear instability, the second-order constitutive relation varies among the corotational Jeffreys model, Oldroyd A model, and the Oldroyd B model, but although they have different disturbance pressures, their disturbance velocities and interface displacements are the same, and therefore, the sheets of the corotational Jeffreys fluid, Oldroyd A fluid, and the Oldroyd B fluid have the same instability behavior characterized by the wave profile and breakup time. The reason for the identical instability behavior is that the effect of different codeformations of the corotational frame, covariant frame, and the contravariant frame is counteracted by the corresponding change in the second-order disturbance pressure, leaving no influence on the second-order velocity. At wavenumbers with maximum instabilities, an increase in the elasticity, or a reduction of the deformation retardation time, leads to a larger linear temporal growth rate, greater second-order disturbance amplitude, and shorter breakup time, thereby enhancing instability. The mechanism of linear instability has been examined using an energy approach, which shows that the main cause of instability is the aerodynamic force.

Significance of Ectodomain Shedding of TNF Receptor 1 in Ocular Surface

We evaluated an anti-inflammatory effect of TNF receptor 1 (TNFR1) ectodomain shedding in ocular surface. Human corneal epithelial cell (HCEC) was first pretreated by TNF-α. Ectodomain shedding was stimulated by uridine triphosphate (UTP) or peptidoglycan (PGN), with or without shedding inhibition using TNF-α processing inhibitor (TAPI). The phosphorylation of the NF-κB inhibitory protein, IκB, was assessed by Western blotting and concentrations of soluble TNFR1 (sTNFR1) in culture medium were analyzed by ELISA. Tear fluid from patients with Sjögren syndrome and graft-versus-host disease (GVHD) was collected and analyzed by ELISA for sTNFR1 concentration. Five dry eye patients underwent topical treatment using diquafosol sodium eye drops, a purinergic P2Y2 receptor agonist, and the tear fluid of the patients was sampled before and 4 weeks after the treatment for sTNFR1 ELISA. Phosphorylation of IκB was diminished by adding UTP or PGN, and this down-regulation of IκB phosphorylation was reversed by adding TAPI. In HCEC medium, sTNFR1 release was increased significantly by adding UTP or PGN, and inhibited significantly by adding TAPI. In the tears of the patients with Sjögren syndrome and GVHD, sTNFR1 expression was upregulated. In the tears of the patients with short breakup time (BUT) dry eye, sTNFR1 concentrations (ng/mL) in the tears were 1.30 ± 0.58 ng/mL for the pretreatment baseline, and 1.64 ± 0.70 after treatment, statistically significantly higher than those for the pretreatment (P < 0.01). Ectodomain shedding of sTNFR1 blocked TNF-α-induced intracellular signaling in corneal epithelium. The upregulation of sTNFR1 in inflamed ocular surfaces suggests an anti-inflammatory role of sTNFR1 ectodomain shedding at the ocular surface.

Weakly nonlinear instability of planar viscous sheets

AbstractA second-order instability analysis has been performed for sinuous disturbances on two-dimensional planar viscous sheets moving in a stationary gas medium using a perturbation technique. The solutions of second-order interface disturbances have been derived for both temporal instability and spatial instability. It has been found that the second-order interface deformation of the fundamental sinuous wave is varicose or dilational, causing disintegration and resulting in ligaments which are interspaced by half a wavelength. The interface deformation has been presented; the breakup time for temporal instability and breakup length for spatial instability have been calculated. An increase in Weber number and gas-to-liquid density ratio extensively increases both the temporal or spatial growth rate and the second-order initial disturbance amplitude, resulting in a shorter breakup time or length, and a more distorted surface deformation. Under normal conditions, viscosity has a stabilizing effect on the first-order temporal or spatial growth rate, but it plays a dual role in the second-order disturbance amplitude. The overall effect of viscosity is minor and complicated. In the typical condition, in which the Weber number is 400 and the gas-to-liquid density ratio is 0.001, viscosity has a weak stabilizing effect when the Reynolds number is larger than 150 or smaller than 10; when the Reynolds number is between 150 and 10, viscosity has a weak destabilizing effect.