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$\begin{figure} \par\includegraphics[width=17.2cm,clip]{aah4152f1.eps}\end{figure}$ Figure 1: Processes responsible for the conversion of the interstellar silicate dust mixture into a chemical equilibrium dust mixture and its final destruction.
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{h4152f2.eps}\end{figure}$ Figure 2: Stability limits in the P-T plane of the minerals formed in chemical equilibrium by the most abundant refractory elements Si, Mg, Fe, Al, Ca in a Solar System element mixture. The dashed lines are the P-T-trajectories corresponding to the disc photosphere at $\tau ={2\over 3}$ (left) and the midplane of the disc (right) for a model with accretion rate $\dot M=10^{-7}~M_{\odot}~\rm yr^{-1}$ .
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In the text

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{h4152f3.eps}\end{figure}$ Figure 3: Partial pressures of SiO in chemical equilibrium between a gas with Solar System element composition and (i) olivine and pyroxene with a mole fraction of 0.7 of the magnesium-rich end-members of the solid solution series, (ii) quartz, and (iii) the partial pressure of SiO of the forsterite-enstatite buffer. The total pressure is P=10^-4 bar. The dashed line shows the vapour pressure of iron.
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In the text

$\begin{figure} \par\includegraphics[width=6.3cm,clip]{aah4152f4.eps}\end{figure}$ Figure 4: Exchange of material between annealed pristine dust components with crystalline structure and equilibrium dust components via the gas-phase. The middle row refers to the vapour species. The solids in the upper and lower row are denoted by obvious abbreviations.
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In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{h4152f5.eps}\end{figure}$ Figure 5: Temperature variation of the diffusion timescales for Mg²⁺, Fe²⁺ cation interdiffusion in olivine and orthopyroxene grains of $0.1~ \mu$ m size with a mole fraction of $\approx$ 10% of the iron-bearing end members of the solution series. Also shown is the characteristic timescale for the conversion of a $0.1~ \mu$ m forsterite grain into an enstatite grain in Si-rich vapour. The dashed lines show the variation of the timescales for radial and vertical mixing in a protoplanetary disc with midplane temperature for a disc model with $\dot M=10^{-7}~M_{\odot}~\rm yr^{-1}$ .
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{h4152f6.eps}\end{figure}$ Figure 6: Model of the radial disc structure for mass accretion rates of $\dot M=10^{-6},\ 10^{-7},\ 10^{-8}~M_{\odot}~\rm yr^{-1}$ . a) Temperature $T_{\rm c}$ at the midplane of the disk. b) Surface density $\Sigma$ of the disc. c) Vertical optical depth $\tau _{\rm c}$ at the midplane. d) Vertical height h of the disk in units of the radius r(aspect ratio).
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{h4152f7.eps}\end{figure}$ Figure 7: Abundance of the elements Fe, Mg, Si, and O not bound in the ISM dust components normalized to Solar System abundances. Disc model with accretion rate $\dot M=1\times10^{-7}~M_{\odot}~\rm yr^{-1}$ .
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In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{h4152f8.eps}\end{figure}$ Figure 8: Relative deviation of the Fe concentration in the gas-phase from the equilibrium concentration for the model with accretion rate $\dot M=1\times 10^{-7}~M_{\odot}$ yr^-1. In the region r>0.5 AU labeled by "growth'', the gas-phase concentration of Fe atoms exceeds that of the equilibrium vapour pressure, in the region labeled by "evaporation'' it is less than the equilibrium concentration. The dashed line shows the evaporation rate of the Mg-Fe-silicates in arbitrary units.
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In the text

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{h4152f9.eps}\end{figure}$ Figure 9: Radial variation of the fraction $f_{\rm Fe}$ of Fe condensed into iron grains, normalized to the solar abundance of Fe. By diffusional mixing the abundance of iron is locally increased over the solar Fe abundance. Disc model with $\dot M= 1\times10^{-7}~M_{\odot}\rm ~yr^{-1}$ .
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In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{h4152f10.eps}\end{figure}$ Figure 10: Radial variation of the fraction of the silicon condensed into the individual Si-bearing condensates and the fraction of silicon present as SiO molecules, normalized to the solar abundance of Si. By diffusional mixing the abundance of Si-compounds is locally increased over the solar Si abundance. Disc model with $\dot M=1\times10^{-7}~M_{\odot}~\rm yr^{-1}$ .
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In the text

$\begin{figure} \par\includegraphics[width=11cm,clip]{h4152f11.eps}\end{figure}$ Figure 11: Cumulative representation of the distribution of the silicon condensed into dust between the different kinds of silicate dust components (interstellar and equilibrium ones) within the protoplanetary disc. The total Si abundance is normalized to the interstellar Si abundance. An enhancement of the Si abundance in the region of evaporation of the interstellar silicates is due to diffusive mixing effects. The grey-shaded areas roughly indicate the regions where the parent bodies of meteorites and cometary nuclei are formed. Stationary disc model with an accretion rate $\dot M=1\times10^{-7}~M_{\odot}~\rm yr^{-1}$ .
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In the text

$\begin{figure} \par\includegraphics[width=17.2cm,clip]{aah4152f1.eps}\end{figure}$	Figure 1: Processes responsible for the conversion of the interstellar silicate dust mixture into a chemical equilibrium dust mixture and its final destruction.
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$\begin{figure} \par\includegraphics[width=6.3cm,clip]{aah4152f4.eps}\end{figure}$	Figure 4: Exchange of material between annealed pristine dust components with crystalline structure and equilibrium dust components via the gas-phase. The middle row refers to the vapour species. The solids in the upper and lower row are denoted by obvious abbreviations.
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$\begin{figure} \par\includegraphics[width=7.8cm,clip]{h4152f6.eps}\end{figure}$	Figure 6: Model of the radial disc structure for mass accretion rates of $\dot M=10^{-6},\ 10^{-7},\ 10^{-8}~M_{\odot}~\rm yr^{-1}$ . a) Temperature $T_{\rm c}$ at the midplane of the disk. b) Surface density $\Sigma$ of the disc. c) Vertical optical depth $\tau _{\rm c}$ at the midplane. d) Vertical height h of the disk in units of the radius r(aspect ratio).
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$\begin{figure} \par\includegraphics[width=8.3cm,clip]{h4152f7.eps}\end{figure}$	Figure 7: Abundance of the elements Fe, Mg, Si, and O not bound in the ISM dust components normalized to Solar System abundances. Disc model with accretion rate $\dot M=1\times10^{-7}~M_{\odot}~\rm yr^{-1}$ .
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$\begin{figure} \par\includegraphics[width=8.2cm,clip]{h4152f9.eps}\end{figure}$	Figure 9: Radial variation of the fraction $f_{\rm Fe}$ of Fe condensed into iron grains, normalized to the solar abundance of Fe. By diffusional mixing the abundance of iron is locally increased over the solar Fe abundance. Disc model with $\dot M= 1\times10^{-7}~M_{\odot}\rm ~yr^{-1}$ .
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$\begin{figure} \par\includegraphics[width=8.4cm,clip]{h4152f10.eps}\end{figure}$	Figure 10: Radial variation of the fraction of the silicon condensed into the individual Si-bearing condensates and the fraction of silicon present as SiO molecules, normalized to the solar abundance of Si. By diffusional mixing the abundance of Si-compounds is locally increased over the solar Si abundance. Disc model with $\dot M=1\times10^{-7}~M_{\odot}~\rm yr^{-1}$ .
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