Exchange direct

The real value of direct interaction between a lecturer and his audience is in the interest he can aronse by presenting the topic in a challenging and perhaps personal way as well as in the give-and-take interaction of direct exchange and participation. I have always tried in my lectnres to give my stndents not only a presentation of facts and concepts, but, based on my own experience and involvement, to convey to them the fascination of exploring the intrigning world of chemistry. 

FIG. 5-18 Direct exchange between parallel circular tubes. 

Evaluation of the AS" s that charac terize an enclosure involves solution of a system of radiation balances on the surfaces. If the assumption is made that all the zones of the enclosure a re gray and emit and reflec t diffusely, then the direct-exchange area ij, as evaluated for the black-siirface pair A and Aj, applies to emission and reflections between them. If at a surface the total leaving-flnx density, emitted phis reflected, is denoted by W (and called by some the radiosity and by others the exitance), radiation balances take the form ... 

Only one direct-view factor F o of direct-exchange area 12 is needed because Fn equals 1 — Fig and Foo equals 1 — Fo equals 1 — FioA /Ao. Then 11 equals A] — 12 and 22 equals A2 — 21, With these substitutions, Eq, (5-131) becomes... 

Rotaiy diyers have been classified as direct, indirect-direct, indirect, and special types. The terms refer to the method of heat transfer, being direct wnen heat is added to or removed from the sohds by direct exchange between flowing gas and solids and being indirect when the heating medium is separated from physical contact with the solids by a metal wall or tube. 

The problem of taking into consideration the actual vacancy-mediated atomic exchange mechanism (rather than the direct exchange model used in most theoretical treatments) recently received some attention. In particular, possible presence of vacancy segregation at various structural inhomogeneities was discussed. However, the estimates of these effects by various authors disagree notably with each other , and there seems to be no general treatment of this problem available. 

Copper (Cu) is deposited in boilers either by direct exchange with iron or by the hydrogen reduction of copper oxide during the corrosion of steel. 

Numbers separated by dashes indicate results in successive reuses Prepared by direct exchange... 

Jordan A, H Frank, ED Hoekstra, S Juuti (1999) New directions exchange of comments on The origins and occurrence of trichloroacetic acid. Atmos Environ 33 4525-4527. 

The reaction is carried out in close-loop reactor connected to a mass spectrometer for 1S02, 180160 and 1602 analyses as a function of time [38], The gases should be in equilibrium with the metallic surface (fast adsorption/desorption steps 1 and f ) If the bulk diffusion is slow (step 6) and the direct exchange (step 5) does occur at a negligible rate, coefficients of surface diffusion Ds can be calculated from the simple relationship between the number of exchanged atoms Ne and given by the model of circular sources developed by Kramer and Andre [41] ... 

Co2+ to Co3+, but also from a direct exchange of Co2+ for Mn2+ produced during the redox reaction. The cobalt in arid soils, as indicated by Han et al. (2002b), mainly occurs in the residual and the Mn oxide (easily reducible oxide) fractions. Furthermore, after water saturation, the Co is transferred mainly from the Mn oxide fraction into the carbonate and exchangeable fraction. This will be discussed in detail in the next chapter. 

These indirect mechanisms may be energetically preferable to a direct exchange of atoms. 

River- and lake-surface areas are small compared with those of land and ocean, and so direct exchange of carbon... 

Distribution locations are included in the company-internal value chain network, if distribution volumes and values are under the control and in the books of the company independent if the warehousing and transportation is outsourced to 3PL distribution companies or not. Therefore, a company value chain network is enclosed with a central control of all volume and value information for the respective network and clear interfaces to customers and suppliers out of the network. While the internal value chain network is focused on material flows evaluated with respective internal costs, dedicated interfaces to multiple suppliers and multiple customers are characterized by material flows, financial flows and mutual instead of one-directional exchange of information as proposed for supply chains by several authors. 

The term direct electrochemistry of proteins means the possibility to detect the direct exchange of electrons between the active site(s) of a protein and a (metallic or inert material) electrode without the help of redox mediators, which might favour an indirect interaction between the electrode and the protein (see the discussion on Electrocatalysis in Chapter 2, Section 1.4.4). This aspect of electrochemistry is not yet as widely explored as it deserves, but the relevant results are now analysed in a rather comprehensive fashion.1 ... 

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