Wicking characteristics

Nitrocellulose and nylon membranes have been widely used in the production of macroarrays (arrays with probe sites of diameter 0.5 to 1 mm), but not so much in the production of microarrays (feature size of 25 to 200 xm) because of a lack of spot resolution (see Sect. 5.2, Spotting of Capture Probes). These membranes exhibit lateral wicking characteristics and the probe therefore tends to spread out from the point of apphcation. Casting of these membranes onto the surface of glass slides is a solution to this problem [28]. 

Quaternary compound. High purity, long chain quaternary ammonium compound used with caustic to improve fabric wicking characteristics, reduce pilling on polyester and to obtain anti-static properties on triacetate fabrics. Used to remove polyvinyl acetate and other resin esters from fabrics. 

In such a case, the wicking characteristics, which determines how quickly and how widely liquid water spreads out laterally on the surface of or within the matrix of the fabric, determines the overall water vapour transport rate through the layered fabrics. 

Fig. 6.6. Effect of fibre mix on wicking characteristics percentage of fine fibres as shown [6].

Wick, G., Characteristics of PET polymer for bottle manufacturing, presentation given at the Society of Plastics Engineers Benelux Seminar, Amsterdam, 20- 21 May, 1980. 

Membranes have been developed that possess improved characteristics with respect to their lateral wicking and spot resolution. The best example of this type of material is anodically oxidized alumina whose structure consists of pores, with very little material forming the walls, possessing a surface area ratio of approximately 500 f. The benefits of this material are its higher sensitivity (more immobilized capture probe) and higher probe densities. 

The Greek asbestos means inextinguishable, but it is apparent from early descriptive comments that the characteristic of incombustibility was implicit (Luschen, 1968). Old synonyms for asbestos, such as salamander stone, referring to a mythical animal that endured fire without harm encompass both meanings, as does the belief that tomb lamps with asbestos wicks burned indefinitely, or at least until all of the oil, but not the wick, was consumed (Theophrastus, brans, by Caley and Richards, 1956). 

The writers have found in their laboratory that invariably after a certain burnoff (depending upon the reactor, temperature, and sample), a subsequent extended period of constant reaction rate, expressed in grams of carbon reacting per unit time, is attained. In this bumoff region, there obviously is equilibrium between the rate of formation of the surface-oxygen complex and its removal with a carbon atom. It is felt that this is the reaction rate most characteristic of a given temperature and should be used in kinetic calculations. In principle, Wicke (31) concurs with this reasoning and reports reactivity data only after the sample has attained a total surface area which is virtually constant. 

The fire from candles has provided fight for centuries. Capillary action carries melted wax along the wick from the candle to the flame. As the wax bums, it produces a characteristic teardrop-shaped flame as air is heated and expands, moving upward. In the microgravity of space, candle flames slightly influenced by gravity are round or dome-shaped. 

The effect of electrical-grade fillers (e.g., silica) on the electrical properties of the adhesive is usually marginal. Generally fillers are not used to improve electrical resistance characteristics such as dielectric strength. The unfilled epoxy is usually optimal as an insulator. Also under conditions of high humidity, fillers may tend to wick moisture and considerably degrade the electrical resistance properties of the adhesive. 

A variety of fluid and pipe materials have been used for heat-pipe construction, and some typical operating characteristics are summarized in Table 12-2. Very high heat fluxes are obtained for this reason research efforts are being devoted to optimum wick designs, novel configurations for specilized applications, etc. Two early theoretical analyses of heat pipes are presented by Cotter, et al. [16,17], The device is in such a state of development that the current research literature should be consulted for latest information. For our purposes we are concerned primarily with applications for the device. 

A wide variety of special durable surface treatments have been used on manufactured fibers. These include treatments for imparting such characteristics as soil resistance, antistatic behavior, and wearer comfort through moisture wicking and transport. Fiber finishes also have been used successfully in promoting adhesion between two materials, as, for example, between polyester tire cord and rubber, and between glass fiber and polyester resin. 

A phase change scheme similar to those described above was proposed by Schwartz and Schmidt 141,142) on the basis of LEED experiments, and by Schiith and Wicke (91,101) on the basis of IR measurements for the oscillatory CO/NO reaction on Pt(lOO). The experiments of Schwartz and Schmidt demonstrated that the transition from the high- to the low-reaction-rate state was accompanied by a change from the 1 x 1 to the hex phase in LEED patterns. The position of the L-CO band in the IR spectra recorded during oscillations varied between the high- and low-reaction-rate states with a relatively high absorption band below 2050 cm present in the low-reaction-rate state, which is characteristic of CO on the Pt(lOO) hex surface. Further proof was provided by Clausius-Clapeyron plot of the conditions for the occurrence of oscillations, which yielded points near the isostere associated with the hex 1 x 1 phase transition (Fig. 14). 

Another mechanism also belongs to this class of models, although in this case there is no phase transition in the first layer of the catalyst, but rather in the adsorbate. Wicke and Bocker (125,126) proposed a model in which a CO-induced transition of the 2 x 2 oxygen structure to the more reactive Vs X Vs// 30° structure is the key step in an oscillation cycle of the CO/O2 reaction on Pd. This was concluded from IR spectra, wherein the characteristic bands for the two different adsorbate structures were identified in the respective phases of the oscillation cycle. Similar results... 

Kim S.J., Seo J.K., Do K.H., (2003), Analytical and experimental investigation on the operational characteristics and the thermal optimization ob a miniature heat pipe with a grooved wick structure, International Journal of heat and Mass Transfer, Vol.46, 2051 - 2063... 

---