Simple replicas

Several simple replica methods for optical microscope examination will be described. Hemsley [201] described two methods for preparing 

Several methods have been specifically developed for the preparation of replicas for the SEM. Peck [238] developed a method to determine the nature and location of volatile and nonvolatile smoke deposits on cigarette filters. Eastman 910 adhesive, methy 1-2-cyanoacrylate monomer liquid, was heated and vaporized adjacent to the specimen as the in situ replicating material. Eastman 910 apparently works well because it polymerizes rapidly in a water environment. However, as a result of the reaction in water, best results are obtained when producing the replica in a dry nitrogen atmosphere. 

Oliver and Mason [239] have used replica methods to assess the effect of surface roughness on the spreading of liquids and to measure contact angles. For stationary studies, small beads of poly(methyl methacrylate) (PMMA) were melted and the molten droplets spread and solidified on the surfaces. Dynamic studies involved polymer melts mounted on a remotely controlled hot stage 

The general replica method for SEM of fibers or other pol3miers is  

An SE image of such a fiber replica is shown in Fig. 4.21. The rough fiber surface texture is associated with the finish. Gordon [242] recently reviewed the artifacts associated with silicone elastomer surface replicas, especially bubbling, and suggests these methods must be used with great care. 

The replication methods described have a basic limitation in that they are all negative impressions of the specimen, which is a major factor in image interpretation. Wood [434] developed a method to provide positive replicas of polymer fiber surfaces. Polymer fibers often have surface coatings, such as finishes in textile fibers, that aid handling but may be volatile in the SEM. However, reflected light microscopy, at high magnifications, reveals only a portion of the curved surface at any one level of focus. Therefore, the depth of focus of the SEM is required. 

Place the specimen onto and into thick tape to permit removal after replication. 

Several simple replica methods for optical microscope examination will be described. Hemsley [237] described two methods for preparing replicas application of a 5% PS solution in benzene (or xylene) or a solution of gelatin in water. These are dried, stripped from the surface and metal shadowed or coated to enhance the detail. A silastic replica method is in general use 

Plastic and silicone replicas for the SEM were compared in a study of large specimens which could not be destroyed. Orthopedic implants, made of HDPE, are large and studies of wear are needed even though the implant will see 

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Our main focus in this chapter has been on the applications of the replica Ornstein-Zernike equations designed by Given and Stell [17-19] for quenched-annealed systems. This theory has been shown to yield interesting results for adsorption of a hard sphere fluid mimicking colloidal suspension, for a system of multiple permeable membranes and for a hard sphere fluid in a matrix of chain molecules. Much room remains to explore even simple quenched-annealed models either in the framework of theoretical approaches or by computer simulation. 

Fig. 3. Shadows cast by simple solidprofiles. It can be seen that the shadows cast in positive and negative replicas are not interchangeable in either shape or tone. (From ref. [54] with permission.)...

Similarly, a fast and simple method to produce print-quality like Ponceau replicas from blots was recently described (68). The positive replicas are the same size as blots and can be stored without loss of intensity. This makes them useful for localizing immunoreactive spots in complex 2D electrophoretograms. 

This replica-trick method was used in the Refs. [60,61] for the polymer network free energy calculation. For averaging of Z"-value over the ensemble of realizations the probability distribution should be chosen. The authors of Refs. [60,61] have used the condition of the thermodynamical equilibrium for the Gibbs probability distribution corresponding to the conditions of network preparation. To our mind, it is a beautiful idea but it should be considered more deeply because not all the types of networks can be described in such a way - many networks cannot be prepared under any equilibrium conditions. Using some additional tube-like approximations, the authors have obtained rather simple results for network elastic constants and for some other parameters. 

Simple Continuous and Discrete Models for Simulating Replica Exchange... 

Select an appropriate subject. First, make sure you know your subject thoroughly one fuzzy step could wreck your entire process. Second, choose a process that is simple and short enough to describe in detail. In a 500-to-800-word essay, for instance, it s better to describe how to build a ship in a bottle than how to construct a life-size replica of Noah s Ark. On the other hand, don t choose a process so simpleminded, mundane, or mechanical that it insults your readers intelligence. (Some years ago at a large state university, students were asked to write a process essay on How to Sharpen a Pencil with the assignment of such stirring, creative topics, it s a wonder that particular English department produced any majors at all that year.)... 

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