This paper presents details of a study that deals with determination of engineering properties, identification of phases of major hydration products, and microstructural characteristics of a zinc-contaminated (referred to as Zn-contaminated in this paper) kaolin clay when it is stabilized by a cement additive. Investigations were carried out with respect to the effect of the level of zinc (Zn) concentration on the overall soil properties including Atterberg limits, water content, pH, stress–strain characteristics, unconfined compressive strength, and secant modulus. In addition, X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry studies were conducted to understand the mechanisms controlling the changes in engineering properties of the stabilized kaolin clay. The study reveals that the level of Zn concentration has a considerable influence on the engineering properties, phases of hydration products formed, and microstructural characteristics of the stabilized kaolin clay. These changes are attributed to the retardant effect of Zn on the hydration and pozzolanic reactions, which in turn alters the phases of hydration products and cementation structure – bonding of the soils. Theoretical simulation of the pore-size distribution curves demonstrates that the cement-stabilized kaolin exhibits bimodal type when the Zn concentration is less than 2%, whereas it displays unimodal type when the Zn concentration is 2%. With an increase in the Zn concentration, the characteristics of the interaggregate pores in terms of volume and mean diameter change considerably, whereas those of intra-aggregate pores remain nearly unchanged.

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Ferric cytochrome P450 (P450) catalyzes intramolecular rearrangements of hydroperoxides to diols by heterolytic scission of the O-O bond and insertion of the terminal oxygen atom into the resulting alcohol. The goals of this work were to further characterize the regio- and stereochemistry of P450 isomerase activity using allylic hydroperoxides and to compare these reactions with NADPH-supported monooxygenations of the corresponding alcohols. Microsomes from phenobarbital-treated rats or purified P450 2B1 catalyzed the conversions of several peroxyquinols, including 2-tert-butyl-4-hydroperoxy-4-methylcyclohexa-2,5-dien-1-one (BMPOOH) and its 2,6-dimethyl derivative (TMPOOH), to diols and to alpha,beta-epoxyquinols by predominant (>93%) cis addition of oxygen to the least hindered double bond. Monooxygenation of the 4-hydroxy analogues (quinols) yielded identical cis-epoxyquinols, and both isomerization and monooxygenation reactions exhibited similar enantioselectivities (32-74% enantiomer excess). Regioselectivities were similar for BMPOOH and BMPOH (epoxyquinol:diol ratios of 5.8-7.6), but quite different for TMPOOH and TMPOH (ratios of 0.6 and 6.4, respectively). Bulky peroxyquinols and quinols derived from the A-rings of 17beta-estradiol and estrone were utilized to further compare these reactions. Both estradiol derivatives underwent approximately equal amounts of 6beta-hydroxylation and 1,2-epoxidation. The estrone derivatives also underwent 6beta-hydroxylation, but only estrone quinol yielded a second product consistent with hydroxylation at position 16. The results support several conclusions. (i) Allylic hydroperoxides may be isomerized to alpha,beta-epoxyalcohols by a heterolytic O-O cleavage mechanism with high stereoselectivity. (ii) Hydroperoxide isomerization is an efficient process relative to monooxygenation. (iii) Isomerase substrates remain in proximity to the P450 oxoferryl intermediate and are rapidly captured by the oxidant. Monooxygenase substrates, on the other hand, may bind to ferric P450 in multiple orientations and undergo more extensive substrate reorientation prior to oxidative attack.

Six methods to determine axial pile capacity directly based on piezocone penetration test (CPTU) data are presented and evaluated. Analyses and evaluation were conducted on three types piles that were failed during pile load testing. The CPT methods, as well as the CPTU methods, were used to estimate the load carrying capacities of the investigated piles (Qp ). Pile load test were used to determine the measured load carrying capacities (Qm). The pile capacities determined using the different methods were compared with the measured pile capacities obtained from the pile load tests. Two criteria were selected as bases of evaluation: the best fit line for Qp versus Qm and the arithmetic mean and standard deviation for the ratio Qp /Qm. Results of the analyses showed that the best methods for determining pile capacity are the CPTU methods.