Porous character

The cross-sectional area of the wick is deterrnined by the required Hquid flow rate and the specific properties of capillary pressure and viscous drag. The mass flow rate is equal to the desired heat-transfer rate divided by the latent heat of vaporization of the fluid. Thus the transfer of 2260 W requires a Hquid (H2O) flow of 1 cm /s at 100°C. Because of porous character, wicks are relatively poor thermal conductors. Radial heat flow through the wick is often the dominant source of temperature loss in a heat pipe therefore, the wick thickness tends to be constrained and rarely exceeds 3 mm. 

Arrays have been produced on filter supports, in microtiter plate wells and on glass slides coated and modified with one-, two- or 3-dimensional surface architectures as shown schematically in Figure 813 19. Glass offers a number of practical advantages, such as mechanical stability and low autofluorescence. Due to the non-porous character of glass chips, the volume of the hybridization solution can be kept to a minimum and probe-target interaction is not limited by diffusion into pores. However, three-... 

The carrier materials used for enzyme adsorption must have a highly porous character and a pore size distribution, which should facihtate a free diffusion of enzyme into the carrier. Furthermore, substrate and product should also be able to diffuse freely. This is especially important in the case of large protein substrates, where diffusion into the pore can be a problem (e.g. whey protein and casein). 

The porous character of the cyanometallates structure is linked to the coordination taken up by the metal (M) in the hexacyanometallate anion, M(CN)f, ", that shapes the salt of the cyanomet-allate anion [238], For example, hexacyanometallates can be considered as a three-dimensional framework of a molecular block, the hexacyanometallate anion, [M(CN)6]", through a transition metal cation Tm+, which connects the N ends of the adjacent blocks [239],... 

Unlike the homogeneous complex, for the supported C-3 several polymer fractions with different molecular weight, including oligomers, were detected (entries 13 and 14). This is presumably a consequence of the porous character of the supported catalysts. 

It could be also concluded that the porous character of the limestone facilitates the radical interactions, pyrosynthesis reactions, by hindering the oxidation process. That is corroborated by the Coronene emissions detected when limestone-coal blend is fed into the fluidised bed to control SO emissions. Coronene formation, the most stable PAH studied... 

In contrast to the slag, char particles collected in cyclones working with moving grate installations and the cyclone material from fluid bed combustors, although free form volatiles, appear to burn well even at 800 C, which can probably be attributed to their highly porous character and consequently a large effective surface area available for reaction [13 ]. Data for fluidized bed volatile char are included in Table 2. 

In addition to the fibrillar morphology of the fibre cell wall, the fibres are characterized by capillaries, voids, and interstices providing the cellulose fibres a highly porous character. The pore size ranged from 5 up to 30 nm and the pore volume fraction attained 1-3% for cotton and wood pulp. However, the total pore volume and pore size distribution are very sensitive to pretreatments. Mercerization leads to a decrease in pore diameter and an enhancement of micropore surface, while enzyme treatments enlarge the existing pores [4]. 

Adherents to this theory have different opinions on the potential at which the film forms. Its thickness, the mechanism of formation, and, most Important, the "cause of passivity. In the earlier theories It was postulated that the passivation follows the formation of a "primary layer" of small conductivity, x lth porous character, which Is sometimes due to precipitation of metal salt on and near the electrode.(32) In the pores the current Increases, and by polarization at an "Umschlagspotentlal" (Vj, = V, Figure 1) an actual passive layer is formed. Thus the essential concept of the passivation process Is connected with the change of the properties (chemical or physical) of the primary film at a certain potential. The passive film Is free from pores and presents a barrier between the metal and the environment. It is electronically conductive and slowly corrodes In solution.(6,8,24,37)... 

Because of their porous character, the films obtained do not necessarily belong to the class of film considered compact. The choice of such a reactive process stems from the fact that direct evaporation or sublimation emerges as an important technological problem. 

Comparing the above-described basic requirements for scaffolds, on the one hand, and the fibrillar and/or porous character of the nano-sized materials manufactured via the MFC approach on the other, one can conclude that these materials could be of biomedical interest. Nano-sized biodegradable biocompatible polymers with a 3-D network structure seem to be particularly attractive because of their nanoporosity and extremely high specific surface (Figures 9.5b, 9.6, 9.7a,b, 9.10b, and 9.11). An additional advantage of these materials is the fact that they are manufactured without the use of any organic solvents as water is the only solvent. 

We suppose the reason for the highly porous character of the SU8 structures lies in the chemical composition of the resist and the cross-linking reaction based on the diffusion of protons. This UV-induced reaction is strongly heat dependent and results in highly nano-porous sidewalls by choosing very long post-exposure times. Thus, one can achieve very slim and tapered ultra-hydrophobic surfaces, with relatively large and square structures on the UV mask. 

The extraction of polar pesticides using nonpolar (Cig and Cg) stationary phases is very difficult and, therefore, polar pesticides are extracted successfully on graphitized carbon black (GCB). The porous character of GCB makes it faster in extraction, without any pH adjustment of the environmental water samples. Many workers have recommended styrene divinyl benzene copolymer as the universal SPE system for the extraction of pesticides that are even moderately polar in nature [89-92]. Ion exchangers have also been used for the extraction of semi-polar or polar pesticides [93, 94], but their range of utility is low due to their low capacity (the capacity is decreased by the ions in the water samples) and their inability to extract pesticides that have similar acidic-basic moieties, which... 

The features of the model also allow the simulation of solids which only differ in their porous or non-porous character by accounting, or not, for imbibition (Eq. 7.56). Unfortunately, porous and compact solids with otherwise exactly the same properties (e.g., particle density) do not exist in reality. Therefore, the experimental investigation has stayed with glass as the compact material and alumina as the porous material. However, two fictitious substances, namely porous glass and compact alumina, both with otherwise the same properties as their real counterparts, were added to model evaluation. 

One approach to obtain a gel from such precursor mixtures and keep the porous character without any prehydrolysis step is the application of cosolvents such as toluene, />-xylene, or mesitylene during sol-gel processing [46]. An... 

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