3) it should be possible to calculate D/1,,,2 if / 3 were known.The value of # I , and hence D/l,,,2, at any axial position can be found by multiplying the slope of the plot of 7 ) versus 2 as shown in Figure 1 (reproduced from the paper by Kattan and Adler) by the velocity of the fluid in the reactor. 9 is defined as the total number of coalescences experienced by the fluid elements between the entrance and any axial position 2 divided by the total number of fluid elements. For example, the slope of the curve is 0 up to a distapce of about 0.15 in. from the inlet, then it rises very sharply and reaches a constant value. If one calculates D/lm2 from this constant value of slope, D/lm2 turns out to be 3.25 (velocity of fluid in the reactor is taken as 16 in./sec.). However, if one assumes a straight line relationship from the origin to the ordinate, at 2 = R. J. Pakula is with Parlte Davis and Company, Detroit, Michigan 48230.

A base-catalysed methyltrimethoxysilane (MTMS) colloidal gel formation was implemented as a cellular automaton (CA) system, specifically diffusion and/or reaction-limited aggregation. The initial characteristic model parameters were determined based on experimental synthesis of MTMS-based, ambient-pressure-dried aerogels. The applicability of the numerical approach to the prediction of gels’ condensation kinetics and their structure was evaluated. The developed model reflects the kinetics properly within the investigated chemical composition range (in strongly reaction-limited aggregation conditions) and, to a slightly lesser extent, the structural properties of aggregates. Ultimately, a relatively simple numerical model reflecting silica-based gel formation was obtained and verified experimentally. The CA simulations have proved valid for understanding the relation between the initial chemical composition and kinetics constants of MTMS-based synthesis and their impact on secondary particle aggregation process kinetics.

The formation of silica aerogels and the kinetics of condensation were investigated numerically. The influence of the reaction-limited to the diffusion-limited aggregation (RLA to DLA) transition on the reaction kinetics curves and the evolution of the aggregate size distribution during condensation were examined. The 2D cellular automaton was developed and applied to reflect the process of secondary particle aggregation. Several tendencies were observed due to the adjustment of the model parameters: the probability of condensation reaction and the particles’ concentration. The final wet-gel structures’ visualizations proves that the structure becomes more dense and compact due to entering the RLA regime. The simulation time (associated with the gelation time) decreased along with the increase in both model parameters. The lower the collision probability, the slower reaction becomes, and particles are more likely to penetrate the structure deeper until they finally join the aggregate. The developed model reflects the condensation process’s nature and its mechanisms properly and indicates a significant potential for further aerogel synthesis investigations and for the prediction of wet-gel properties according to condensation parameters.

Okolice Łodzi stały się w początkowej fazie I wojny światowej terenem krwawych walk toczonych w listopadzie i grudniu 1914 roku między wojskami niemieckimi i rosyjskimi, które określa się mianem Operacji łódzkiej. Pozostałością tych krwawych wydarzeń są cmentarze wojenne z mogiłami żołnierzy obu armii, które zostały wybudowane przez władze niemieckie w czasie I wojny światowej, oraz osobne grupy grobów znajdujące się w obrębie innych cmentarzy lub znajdujące się poza cmentarzami. Do dzisiaj na terenie województwa łódzkiego zachowało się 176 cmentarzy i mogił z tego czasu. W okresie PRL groby te i cmentarze niszczały i popadały w zapomnienie. Sytuacja zmieniła się w latach 90. XX wieku, gdy zainicjowane zostały działania renowacyjne i popularyzatorskie mające na celu przypomnienie Operacji łódzkiej. Zabytkowe groby i cmentarze otoczono opieką i stały się one ważnym elementem programów edukacyjnych, a także atrakcją turystyczną. W ramach projektów turystyczno-historycznych opracowano szlaki prowadzące śladami działań I wojny światowej i najciekawszych cmentarzy.