Detachment Angle Research Articles

Clinical outcomes of non-Descemet stripping automated endothelial keratoplasty

To describe the results of non-Descemet stripping automated endothelial keratoplasty (non-DSAEK). Retrospective, interventional, consecutive clinical case series. Twenty-three patients underwent non-DSAEK from January 2010 to February 2011. The various indications were pseudophakic corneal edema, aphakic corneal edema, failed graft, iridocorneal endothelial syndrome and congenital glaucoma. Corneal edema cleared in all patients within 1-4 weeks. Mean follow-up duration was 7.6 months. Post-operative best corrected visual acuity ranged from 20/400 to 20/40. Fourteen patients had co-morbid factors affecting the vision. No patient had interface haze. Immediate post-operative complications were partial graft detachment (1 patient) and secondary angle closure (1 patient). Corneal clarity was restored following secondary interventions. One late post-operative complication was graft rejection at 6 months, leading to graft failure. Non-DSAEK is a safe and viable option in cases of corneal decompensation when the Descemet membrane is non-pathological.

Surface flotation of particles on liquids. Principles and applications

Surface flotation was modeled by a spherical particle residing at the liquid/gas interface and forces operating in the system. Basing on this model and known expressions for the forces, different equations were presented, which relate (1) attachment contact angle with particle central angle as a function of particle size and density as well as liquid density and surface tension, (2) detachment contact angle as a function of particle size and density as well as liquid density and surface tension for the case when the particle starts to sink in the liquid, and (3) recalculated rest contact angle for the case when the mass of particle is neglected. The presented formulas can be useful for determination of attachment, detachment, and rest contact angles, and for selection of reference liquids for Washburn-type techniques of contact angle determination as well as for finding the critical surface tension of wetting.

Retrephination of Eccentric Donor Graft for Descemet Stripping Automated Endothelial Keratoplasty

We describe a technique of intraoperative eccentric retrephination of Descemet stripping automated endothelial keratoplasty (DSAEK) donor graft to avoid the presence of epithelium on the graft lenticule. Trephination of the DSAEK graft may prove to be very challenging for surgeons, especially when flap diameter is small; this can result in an eccentric trephination and the presence of epithelium on the graft. Insertion of epithelium with DSAEK donor graft into the anterior chamber could result in epithelial ingrowth and downgrowth, complications that may lead to poor visual outcomes, graft detachment, and anterior chamber angle closure. A second eccentric retrephination is a simple and easy-to-perform intraoperative surgical step that could avoid the presence of corneal epithelium on the DSAEK donor graft.

A new model of repulsive force in eddy current separation for recovering waste toner cartridges

Eddy current separation (ECS) is an efficient method for separating aluminum from plastic in crushed waste toner cartridge (TCs). However, in China, ECS quality of aluminum from plastic is rather low in production practice. Repeating separation even manual sorting is required in the production. Improving separation quality of aluminum has been the pressing problem in the recovery of waste TCs. Furthermore, improving ECS quality can reduce the secondary-pollution (furan and dioxin) brought by plastic in later smelting process for the purification of recovered aluminum. Thus, a new model of repulsive force containing impact factors (machine: B r , k, R, S m , B m ; material: S p , V, γ; and operation: ω m , v , δ) of the separation process was constructed for guiding the ECS process of waste TCs recovering in this paper. For testing whether the model of repulsive force was suitable to guide the ECS, calculation and experiment of detachment angle of aluminum flake were studied. The calculation results of the detachment angles were agreed with the testing experiment. It indicates that the model is suitable for guiding the ECS of waste TCs recovering.

The effect of slope angle on splash detachment in an unmanaged Japanese cypress plantation forest

AbstractA field investigation of the effects of rainfall and slope angle on splash detachment was conducted for 5 months, using 27 splash cups in a Japanese cypress plantation in southern Japan. The unit, kinetic energy of throughfall (J m−2 mm−1), was found to be constant and independent of rainfall intensity, indicating that splash detachment can be related to both throughfall intensity and soil slope. The linear correlation coefficient was highly significant for both the maximum throughfall intensity over 1 h (RI1h) and the average splash detachment of all splash cups, although individual cups varied widely. No consistent relationship was found between the splash detachment rate and slope angle for individual periods. This variation in the relationship between splash detachment and slope angle was attributed to the effect of soil crusting and ponding on splash detachment. Splash detachment on a gentler slope (14° ) exhibited a strong relationship with the maximum throughfall intensity lasting for short periods of 10–30 min. In contrast, the splash detachment from slopes > 35° highly correlated with the maximum throughfall intensity over 3 h. This suggests that a longer period is required to prevent the splash detachment due to ponded water on steeper slopes. On gentler slopes, prolonged rainfall may result in a higher ponding depth, thereby reducing raindrop impact and causing less splash detachment. Thus, under forest canopies, the effect of slope angle on the rainfall parameter should be incorporated into future splash erosion models. Copyright © 2010 John Wiley & Sons, Ltd.

Wetting and Absorption of Water Drops on Nafion Films

Water drops on Nafion films caused the surface to switch from being hydrophobic to being hydrophilic. Contact angle hysteresis of >70 degrees between advancing and receding values were obtained by the Wilhelmy plate technique. Sessile drop measurements were consistent with the advancing contact angle; the sessile drop contact angle was 108 degrees . Water drop adhesion, as measured by the detachment angle on an inclined plane, showed much stronger water adhesion on Nafion than Teflon. Sessile water and methanol drops caused dry Nafion films to deflect. The flexure went through a maximum with time. Flexure increased with contact area of the drop, but was insensitive to the film thickness. Methanol drops spread more on Nafion and caused larger film flexure than water. The results suggest that the Nafion surface was initially hydrophobic but water and methanol drops caused hydrophilic sulfonic acid domains to be drawn to the Nafion surface. Local swelling of the film beneath the water drop caused the film to buckle. The maximum flexure is suggested to result from motion of a water swelling front through the Nafion film.

Ocular Uveitis as the Initial Presentation of Syphilis

To document the characteristics of syphilitic patients who present with ocular uveitis clinically and are diagnosed by an ophthalmologist first. Retrospective chart review of uveitis patients in the department of ophthalmology between 1992 and 2004 was done. We included only those patients with positive serologic tests, active ocular uveitis, and record of detailed examination. There were 8 syphilitic patients (14 eyes) who presented with ocular syphilis clinically and who were diagnosed by an ophthalmologist first. The ocular diagnosis included panuveitis (11 eyes, 78.6%), anterior uveitis (2 eyes, 14.3%), and posterior uveitis (1 eye, 7.1%). Two patients (25%) had unilateral eye involvement, and 6 patients (75%) had involvement in bilateral eyes. One patient (2 eyes) with panuveitis also had bilateral exudative retinal detachment and chronic angle closure glaucoma. All 8 patients were negative for human immunodeficiency virus. Dark field examination of aqueous humor in 2 cases revealed Treponema pallidum, which was confirmed by immunofluorescent test. Treatment included systemic penicillin in 7 patients and oral tetracycline in 1 patient (due to penicillin allergy). Visual function and uveitis improved after treatment in all patients. Syphilis can be presented initially as ocular uveitis without obvious systemic manifestation. Ophthalmologists play an important role in the early diagnosis and treatment of syphilis. If treated early enough, the response is good, even if the patient is allergic to penicillin. Awareness of the multiple manifestations of ocular syphilis is the key to early detection of the disease.

Frictional adhesion: a new angle on gecko attachment

Directional arrays of branched microscopic setae constitute a dry adhesive on the toes of pad-bearing geckos, nature's supreme climbers. Geckos are easily and rapidly able to detach their toes as they climb. There are two known mechanisms of detachment: (1) on the microscale, the seta detaches when the shaft reaches a critical angle with the substrate, and (2) on the macroscale, geckos hyperextend their toes, apparently peeling like tape. This raises the question of how geckos prevent detachment while inverted on the ceiling, where body weight should cause toes to peel and setal angles to increase. Geckos use opposing feet and toes while inverted, possibly to maintain shear forces that prevent detachment of setae or peeling of toes. If detachment occurs by macroscale peeling of toes, the peel angle should monotonically decrease with applied force. In contrast, if adhesive force is limited by microscale detachment of setae at a critical angle, the toe detachment angle should be independent of applied force. We tested the hypothesis that adhesion is increased by shear force in isolated setal arrays and live gecko toes. We also tested the corollary hypotheses that (1) adhesion in toes and arrays is limited as on the microscale by a critical angle, or (2) on the macroscale by adhesive strength as predicted for adhesive tapes. We found that adhesion depended directly on shear force, and was independent of detachment angle. Therefore we reject the hypothesis that gecko toes peel like tape. The linear relation between adhesion and shear force is consistent with a critical angle of release in live gecko toes and isolated setal arrays, and also with our prior observations of single setae. We introduced a new model, frictional adhesion, for gecko pad attachment and compared it to existing models of adhesive contacts. In an analysis of clinging stability of a gecko on an inclined plane each adhesive model predicted a different force control strategy. The frictional adhesion model provides an explanation for the very low detachment forces observed in climbing geckos that does not depend on toe peeling.

Performances of a waste recycling separator with permanent magnets

The polarization fixed point method coupled with Green function method is used for computation the magnetic field. Magnetic force is obtained by using Maxwell tensor. The procedure avoids the spurious forces introduced by artificial boundary or by meshing the air zone. As a performance of the separator, the difference between the detachment angle of ferromagnetic and nonferromagnetic bodies is evaluated.

Modeling the Cycles of Growth and Detachment of Bubbles in Carbonated Beverages

In this paper, a model for the formation of bubbles in carbonated beverages is presented. It has previously been shown that bubbles form from cellulose fibers within such beverages and the passage of such bubbles from the fibers to the liquid surface has been modeled. A model is thus presented here that considers the process of formation, which is governed by diffusion through the fiber and bubble surfaces. The model comprises two stages, growth and detachment, and it is shown here that both play an important role. The latter process is found to occur over a much shorter time scale than the former, enabling the models to be partially decoupled. The total number of bubbles released from individual fibers over time is found to be approximated well by an exponential relationship, and the parameters in this relationship are presented for a range of different detachment angles and fiber sizes. It is found that bubble formation is promoted in narrow, long tubes, but that the time constant is solely determined by the rate of diffusion across the liquid surface. The surface tension is found to have minimal influence on the number of bubbles produced.

Stratigraphic signatures of translation of thrust‐sheet top basins over low‐angle detachment faults

Abstract Low‐angle detachment faults and thrust‐sheet top basins are common features in foreland basins. However, in stratigraphic analysis their influence on sequence architecture is commonly neglected. Usually, only eustatic sea level and changing flexural subsidence are accounted for, and when deformation is considered, the emphasis is on the generation of local thrust‐flank unconformities. This study analyses the effects of detachment angle and repetitive detachment activation on stratigraphic stacking patterns in a large thrust‐sheet top basin by applying a three‐dimensional numerical model.Model experiments show that displacement over low‐angle faults (2–6°) at moderate rates (∼5.0 m kyr−1) results in a vertical uplift component sufficient to counteract the background flexural subsidence rate. Consequently, the basin‐wide accommodation space is reduced, fluvio‐deltaic systems carried by the thrust‐sheet prograde and part of the sediment supply is spilled over towards adjacent basins. The intensity of the forced regression and the interconnectedness of fluvial sheet sandstones increases with the dip angle of the detachment fault or rate of displacement. In addition, the delta plain is susceptible to the formation of incised valleys during eustatic falls because these events are less compensated by regional flexural subsidence, than they would be in the absence of fault displacement.

Prediction of bubble diameter at detachment from a wall orifice in liquid cross-flow under reduced and normal gravity conditions

Bubble formation and detachment is an integral part of the two-phase flow science. The objective of the present work is to theoretically investigate the effects of liquid cross-flow velocity, gas flow rate embodied in the momentum flux force, and orifice diameter on bubble formation and detachment in a wall-bubble injection configuration. A two-dimensional one-stage theoretical model based on a global force balance on the bubble evolving from a wall orifice in a cross liquid flow is presented in this work. In this model, relevant forces acting on the evolving bubble are expressed in terms of the bubble center of mass coordinates and solved simultaneously. Relevant forces in low gravity included the momentum flux, shear-lift, surface tension, drag and inertia forces. Under normal gravity conditions, the buoyancy force, which is dominant under such conditions, can be added to the force balance. Two detachment criteria were applicable depending on the gas to liquid momentum force ratio. For low ratios, the time when the bubble acceleration in the direction of the detachment angle is greater or equal to zero is calculated from the bubble x and y coordinates. This time is taken as the time at which all the detaching forces that are acting on the bubble are greater or equal to the attaching forces. For high gas to liquid momentum force ratios, the time at which the y coordinate less the bubble radius equals zero is calculated. The bubble diameter is evaluated at this time as the diameter at detachment from the fact that the bubble volume is simply given by the product of the gas flow rate and time elapsed. Comparison of the model's predictions was also made with predictions from a two-dimensional normal gravity model based on Kumar–Kuloor formulation and such a comparison is presented in this work.

Characterization of materials by Hallimond tube flotation. Part 2: maximum size of floating particles and contact angle

An equation more complete than any existing one in literature for the upper size limit of flotation was presented and tested against mercury drops, spherical particles of sulfur, and paraffin-coated grains of different solids. It was demonstrated that flotation tests combined with the derived equation make it possible to characterize and measure floatability and hydrophobicity of spherical and irregular particles in the form of the equilibrium and detachment angle of the bubble-particle aggregate. The maximum size of floating particles values and the equilibrium as well as detachment contact angles were determined for various hydrophobic materials including sulfur, pyrite, mercury, germanium, silicon, talc, fluorite, silicon carbide, silver iodide, ilmenite, arsenic oxide, diamond, graphite, molybdenite, and boric acid. Also resulting from this study is the confirmation that the monobubble Hallimond tube is a valuable tool for characterizing and comparing flotation of different systems.

Removal of orbital debris from low Earth orbit by laser-generated drag

ences between the planar and conical shock-wave detachment angles and behavior become greater as the ratio of specific heats decreases from 1.67 to 1.0+. The usually available results for y = 1.4 are not good approximations over the possible range of ratio of specific heats. A complete set of charts, in the format of Ref. 1, is available in Patel et al. for y = 1.0+, 1.1,1.2,1.3,1.4,1.5,1.6, and 1.67.

Engineering approach to the prediction of shock patterns in bounded high-speed flows

A two-dimensional symmetric wedge configuration representative of a single high-speed intake in steady flow was investigated. The analysis presented here is intended as an engineering approach for estimating certain features of the internal shock system. The primary interest here is the prediction of the size and location of the almost-normal shock wave that develops when the leading-edge shocks intersect at angles above a certain critical value that is less than the wedge detachment angle. The almost-normal shock wave is frequently referred to as the 'Mach stem', Parametric studies enabled the sensitivity of the Mach stem height to various flowfield parameters to be examined, thus indicating how accurately these parameters must be measured in a given experiment. Results of these predictions were compared with those of a steady-flow experiment performed at nominal freestream Mach numbers from 2.8 to 5. The predicted stem heights were consistently lower than the mean experimental values, attributable both to experimental uncertainties and to certain simplifying assumptions used in the analysis. Modification of these assumptions to better represent the test environment improved the analytical results.

On the Mach Number Variation in Steady Flows of Dense Hydrocarbons

We consider the steady flow of five commonly encountered hydrocarbons in their dense gas regime. Isentropic flows are first examined and it is shown that dense gas effects lead to a non-monotone variation of the Mach number with density. It is also demonstrated that these effects may give rise to an increase, rather than the classical decrease, in the Mach number across oblique compression shocks. Significant increases in the shock detachment angle are also reported.

Adhesion of quartz particles in liquid media

The angle of detachment, sediment volume and relative viscosity of monodisperse quartz suspensions were investigated both in simple liquids and in liquid mixtures of different polarities as functions of particle size and contact time. For water-alcohol mixtures, the angle of detachment, the sediment volume and the viscosity of quartz particles of different sizes yielded maximum curves as functions of the alcohol concentration However, benzene-alcohol mixture gave curves with minimum. The extent of the changes were influenced by the alcohol chain length and the particle size. The adhesion, defined by the sine of the angle of detachment, correlated with the sediment volume of the suspensions and with the relative viscosity of the suspensions. Variations of the interaction between the quartz particles and the media was assumed, which is due to the oriented adsorption of the molecules. The continuity was also influenced by the specific surface area of the particles and the contact time. The adhesion forces between the particles and the planar surface are determined by the particle size and the structure of the adsorption layer.

Design Parameters for Vibratory Mango Harvesting System

ABSTRACT An inertia type slider crank limb shaker was designed and developed for harvesting mango fruits. Field tests on two local cultivars showed that to obtain maximum fruit removal with minimum tree damage, the shaker should be operated in the range of 76 to 102 mm eccentricity and 13 to 11 r/s for 4 s. To minimize tree damage, the clamp for holding the tree limb should be provided with a padding material having high shock absorbing characteristics. Among the cushioning materials tested, the nylon net had the lowest fragility factor and the lowest coefficient of restitution and its use is recommended for catching the fruits. The maximum limb displacement (S^^^^) ^^^ shaking frequency (f) follow the equation S^^^ = aQ exp (-Cof) where SLQ and CQ are coefficients. Apparent stiffness (K) of the limb increases with increase in shaking frequency according to equation fi = CQK where CQ is a coefficient. Fruit removal percentage (FR) is given by the regression equation FR = CjCf) + C2(s) + C3(fs) + C4(D) where D is limb diameter and Cj, C2, C3 and C4 are coefficients. The fruit detachment force to fruit weight ratio (FAV) is related to fruit size (Df) and detachment angle (d) by the equation of form L^CF/W) = CQ + CjCDf) + C2('d ) where CQ, Ci, C2 are coefficients.

Adhesion of quartz particles on glass and properties of their suspensions in the presence of a cationic surfactant

Angle of detachment, sediment volume and relative viscosity of monodisperse quartz fractions were examined in media of varying polarity. The particles were made hydrophobic by adsorption of a cationic surfactant. A critical value of surface excess n σ(ν) was found, at which the angle of detachment had a maximum value in water and a minimum in apolar liquids. Change in the sediment volume and the viscosity of the suspensions may be directly correlated with change in the adhesion. Sediment volume and viscosity of the partially hydrophobized quartz particles in media with different polarity depend on the surface coverage and the particle size of the fraction. The changes in adhesion could be explained by the changes in surface coverage and the lyophilicity in the different liquids.

Stability of Shock Waves Attached to Wedges and Cones

A numerical study of a reduced set of the Euler equations shows that both weak and strong attached shock waves are stable configurations depending on the boundary conditions imposed. The results obtained are in good agreement with experimental observations and with the minimum entropy principle. A heuristic ex- planation of the behavior observed is given in terms of quasistatic considerations. OR flow over a wedge or cone, whose deflection angle is less than the angle associated with shock detachment for the incoming supersonic flow, it is a well-known fact that the steady-state Euler equations admit two different solutions. Each solution is distinguished by the strength of the attached oblique shock. Thus a solution is labeled strong or weak if the shock-wave inclination is, respectively, greater than or less than the shock-wave inclination at detachment. For the strong shock solution, the flow is always subsonic downstream of the shock; for the weak shock solution, the flow is supersonic downstream of the shock, except for a small range of deflection angles in the neighborhood of the detachment angle where the weak shock is followed by subsonic flow. This small region will be ignored in the present work. The existence of multiple solutions has attracted considerable theoretical scrutiny, which has mainly succeeded in obscuring the problem. Indeed, our understanding of this problem has changed little since 1948, when Courant and Friedrichs1 wrote .. .The question arises which of the two actually occurs. It has frequently been stated that the strong one is unstable and that, therefore, only the weak one could occur. A convincing proof of this instability has apparently never been given. Quite aside from the question of stability, the problem of determining which of the possible shocks occurs cannot be formulated and an- swered without taking the boundary conditions at infinity into account. The confusion has come about because the question posed by Courant and Friedrichs and every succeeding investigator has not been the proper question to ask. The question should not be which solution actually occurs, since we have ex- perimental evidence2 that both the weak and the strong solutions do occur, but under what conditions do one or the other solutions occur. The answer to this latter question obviously depends on the boundary conditions, as already indicated by Courant and Friedrichs. Moreover, since the nature of steady-state solution is elliptic for the strong shock and hyperbolic for the weak shock, we should suspect that each problem is governed by a different set of boundary conditions. The purpose of this paper is, therefore, to study the stability of the weak and strong solutions with boundary conditions which are appropriate to each case under in- vestigation.