Treatment of contacts

Many process flows require a bottom contact electrode configuration. For these processes one solution to the bottom contact problem is to treat the contacts to improve the device behavior. 

For both crystal texture improvement and work function engineering SAMs are particularly favorable and straightforward to handle. When deposited under the right conditions, they selectively attach only to the electrodes and selflimit their growth to one monolayer. This allows for straightforward deposition without the need for any additional lateral patterning or precise application to limit the layer s thickness. 

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Fig. 4. Schematic of the JKR treatment of contact mechanics calculations. The point (, a, P) corresponds to the actual state under the action of interfacial forces and applied load P. P is the equivalent Hertzian load corresponding to contact radius a between the two surfaces, ( o, P) and (S], a, P ) are the Hertzian contact points. The net stored elastic energy and displacement S are calculated as the difference of steps 1 and 2.

The purpose of this paper will be to develop a generalized treatment extending the earlier mixed micelle model (I4) to nonideal mixed surfactant monolayers in micellar systems. In this work, a thermodynamic model for nonionic surfactant mixtures is developed which can also be applied empirically to mixtures containing ionic surfactants. The form of the model is designed to allow for future generalization to multiple components, other interfaces and the treatment of contact angles. The use of the pseudo-phase separation approach and regular solution approximation are dictated by the requirement that the model be sufficiently tractable to be applied in realistic situations of interest. 

One interesting feature of the functional form derived here is the direct relationship of the activity coefficients and composition between the micellar and surface psuedo-phases. This allows a comparison of nonideal interactions in the micelle and monolayer as modeled by their respective net interaction parameters. In principle, this form may also allow extension to more complicated situations such as the treatment of contact angles in nonideal mixed surfactant systems. Here, the functional form derived above depends on differences in surface pressures and these may be directly obtained from experimentally measured parameters under the proper conditions (30). 

A number of chapters have been overhauled so thoroughly that they bear only minor resemblance to their counterparts in the first edition. The thermodynamics of polymer solutions is introduced in connection with osmometry and the drainage and spatial extension of polymer coils is discussed in connection with viscosity. The treatment of contact angle is expanded so that it is presented on a more equal footing with surface tension in the presentation of liquid surfaces. Steric stabilization as a protective mechanism against flocculation is discussed along with the classical DLVO theory. 

Numerical calculations of (Sz) at 300 K obtained with eq. (22) for all /((III) free ions are collected in table 3 (Golding and Halton, 1972). Pinkerton et al. (1985) have demonstrated that (Sz) are relatively insensitive to the choice of various sets of reported spin-orbit coupling constants. Moreover, except for R = Sm and Eu, (Sz) displays a minor dependence on the temperature and the data calculated at 300 K (table 3) are amenable for a reliable treatment of contact shifts in solution around room temperature. The close proximity of excited states possessing different J manifolds for Sm(III) requires a precise calculation of (Sz) at each temperature as is the case for R = Eu. However, the latter metal brings some specific complications associated with the absence of a well-defined gj value for its 7 = 0 ground state. Golding... 

Nedocromil sodium has been found to be effective in treating SAC and GPC. In SAC, there was found to be significant improvement in itching, conjimctival injection, and overall disease when compared with placebo. In treatment of contact lens-induced GPC, when compared with placebo, the medication reduces itching and mucous discharge. Nedocromil is available as a clear, yellow, 2% ophthalmic solution, and it differs from other mast cell stabilizers by having a twice-daily dosage. 

Contact dermatitis may resolve without treatment within days but may take up to 3 weeks in allergic cases. In contrast, in toxic cases resolution may take 3 to 6 weeks. Avoidance of the offending agent is the first step in the treatment of contact dermatitis, with emphasis given to decreasing rubbing and scratching. Snpportive therapy includes cool compresses. In addition, application of topical steroid ointment or cream preceded by cool compresses temporarily relieves symptoms. Steroid use should be limited to 5 to 10 days due to the risk of tachyphylaxis, atrophy of the skin, and increased risk of infection. 

It is appropriate to stress that the above argument is thermodynamical, and hence phenomenological. The transition from the film, with tension y to the droplet, with surface tension is taken as sharp, just as in the macroscopic treatment of contact angles. In other words, it is ignored that on a colloidal scale... 

Since specific adsorption is an important phenomenon in electrochemistry, the solution/metal interface has nevertheless been studied in various ways. An ion is considered to be adsorbed specifically in the inner Helmholtz plane when it is partially dehydrated and in direct contact with the metal surface (see, e.g.. Ref. 15). On the other hand, an ion that is adsorbed further away from the electrode with its hydration shell essentially intact is considered to be adsorbed non-specifically in the outer Helmholtz plane . In the classical treatment of contact adsorption, the balance between the energy of hydration of the ion and the strength of the image interactions determines which ions are specifically adsorbed and which ones are not... 

Nonpharmacological treatment of contact dermatitis includes avoiding direct contact with the causative irritant. The patient should use protective gloves and clothing if the chemical agent is associated with his or her employment. 

Other reports " describe essentially similar rises in ciclosporin levels during the use of ketoconazole. The effects of ketoconazole on ciclosporin were found to be slightly increased (from 80 to 85%) when diltiazem was also given. Ketoconazole 2% cream has been found not interact with ciclosporin 1 mg/kg daily in the treatment of contact allergic dermatitis and the ciclosporin dosage does not need to be reduced. Impaired glucose tolerance has been attributed to the use of ketoconazole and ciclosporin in one patient. ... 

In their treatment of contact angle hysteresis due to chemical heterogeneity, Johnson and Dettre used a theoretical analysis similar to the one they used for surface roughness. 

The reason for this special treatment of contact catalysis, i.e., catalysis at solid surfaces, lies in the fact that although much is known about surface chemistry, little is known today about the active centers at the surface of solids. While considerable knowledge has been gained about the structure, thermodynamics and kinetics of many free radicals, not even the chemical identity of adsorption complexes, i.e., the active centers at solid surfaces, is known with certainty in any particular instance. The obstacles in the way of detailed understanding are further aggravated by the difficulty of reproducing identical batches of solid catalysts, even under very strict rules of... 

The necessity of taking into consideration the two angles complicates the thermodynamic treatment of contact wetting. It must be considered that in the adhesive s concrete case, the liquid absorption on the solid surface determines the decrease of a. Introduc-... 

Nichols JJ, Bickle KM, Zink RC, Schiewe MD, Haque RM, Nichols KK. Safety and efficacy of topical azithromycin ophthalmic solution 1.0% in the treatment of contact lens-related dry eye. Eye Contact Lens 2012 38(2) 73-9. 

The compliance based treatment of contact mechanics is useful because it relies only on directly measurable quantities, these being the load, displacement and contact radius. It does not rely on information relating to the detailed stress distribution within the material. Often, however, it is useful to have more information about this stress distribution. Analytic theories of non-adhesive contact generally assume that the contact is frictionless, so that the interface is not able to support shear stresses. The Hertzian form of the radial distribution of the normal stress, or contact pressure, for frictionless contact is given by the following expression [1 ] ... 

We now turn our attention to an important aspect of solving tire problems - the treatment of contact constraints. The contact problem to be solved is one of the two bodies contacting across their respective surfaces. The impenetrability of the two bodies (normal contact) will manifest itself as a set of unilateral constraints... 

Bearing in mind the limitations and approximations made for Dupre s rule (O 4.50) and Young s equation (O 4.29), finally consider the common treatment of contact angle data which makes use of the combination of the two equations ... 

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