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1.
Results of two urgent and practically important directions of research on the indirect oxidation of organic compounds by highly reactive intermediates generated electrochemically from oxygen (HO2
–, HO2
·, HO·) are considered and orderly arranged. The studies in question are the indirect synthesis and mineralization of organic toxicants in waste water. 相似文献
2.
3.
We describe and interpret computer simulations of the time evolution of a binary alloy on a cubic lattice, with nearest neighbor interactions favoring like pairs of atoms. Initially the atoms are arranged at random; the time evolution proceeds by random interchanges of nearest neighbor pairs, using probabilities compatible with the equilibrium Gibbs distribution at temperatureT. For temperatures 0.59Tc, 0.81 Tc, and 0.89T
c, with density of A atoms equal to that in the B-rich phase at coexistence, the density C1 of clusters ofl A atoms approximately satisfies the following empirical formulas: C1 w(1 –)3 andC
1, (1 –)4Q1w1 (2 l 10). Herew is a parameter and we defineQ
l
=
K
e
–E(K)
, where the sum goes over all translationally nonequivalentl-particle clusters andE(K) is the energy of formation of the clusterK. Forl > 10,Q
1 is not known exactly; so we use an extrapolation formulaQ
l
Aw
s
–l
l
– exp(–bl
), wherew
s is the value ofw at coexistence. The same formula (withw > w
s) also fits the observed values of C, (for small values ofl) at densities greater than the coexistence density (forT=0.59Tc): When the supersaturation is small, the simulations show apparently metastable states, a theoretical estimate of whose lifetime is compatible with the observations. For higher supersaturation the system is observed to undergo a slow process of segregation into two coexisting phases (andw therefore changes slowly with time). These results may be interpreted as a more quantitative formulation (and confirmation) of ideas used in standard nucleation theory. No evidence for a spinodal transition is found.Supported by AFOSR Grant No. 73-2430D and by ERDA Contract No. EY-76-C-02-3077*000. 相似文献
4.
The locality of underground water, contaminated with cyanides, has been successfully cleaned by using the hydraulic barrier method (assembly of pumped wells) since 1986. The average cyanide concentrations in the outflow exceeded 35 m per litre. Contamination had to be eliminated before the discharge into the sewer system. The radiation approach “in situ” i.e. decomposition of cyanides by barrier, was applied and is still being used today. The cyanide concentration was lowered more than one order of magnitude. This process was approved by the Czechoslovak radiation security authorities and further applications of “in Situ” regeneration of underground water contamination is anticipated. 相似文献
5.
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6.
《Arabian Journal of Chemistry》2022,15(6):103852
A simple and easily scalable “wet” procedure was used to prepare nanocrystalline cerium oxide capable of destroying the toxic organophosphate pesticide parathion methyl. The synthetic procedure consists of the direct precipitation of cerous salt with aqueous ammonia in the absence of CO2. The prepared cerium oxide was able to decompose the organophosphate compounds both in nonpolar (e.g., heptane) and polar aprotic (e.g., acetonitrile) solvents. However, in solvents with hydrogen-bond donating ability, the –OH groups on the cerium oxide surface were solvated and inactivated. The preferential solvation model was used to express the experimental dependencies of the cerium oxide degradation efficiency on the composition of the water-acetonitrile mixture. In certain solvent systems, some empirical polarity scales, such as the alpha-scale or the Dimrodth-Richardt parameter ET(30), may be correlated with the degradation efficiency of cerium oxide. 相似文献
7.
8.
9.
We consider site percolation on Z
d, directed edges going from any sZ
d to s+A
1,..., s+A
n, where A
1,..., A
n are the same for all sites and at least two of them are noncollinear. A site is closed if it belongs to p+Block, where p is a point in a Poisson distribution in R
dZ
d with a density and Block={sL: |s|M}+{sR
d: |s|}, where L is a linear subspace of R
d, |·| is the Euclidean norm, =max(|A
1|,..., |A
n|) and M is a parameter. We study the behavior of *, the critical value, and P
closed*, corresponding critical percentage of closed sites, when M. Denote R
d/L the factor space. Call two nonzero vectors U, V codirected if U=kV, where k>0. Theorem. If there are A
i and A
j whose projections to R
d/L are not codirected, then *1/M
dim(L) and P
closed* remains separated both from 0 and 1 when M. If projections of all A
1,..., A
n to R
d/L are codirected, then *1/M
dim(L)+1 and P
closed*1/M when M. 相似文献
10.