The total synthesis of a highly potent cytotoxic marine natural product, phorboxazole A, is described. Both a palladium(II)-mediated and a palladium(II)-catalyzed intramolecular alkoxycarbonylation were used as key steps for the preparation of the two cis-2,6-disubstituted tetrahydropyran rings (C22-C26 and C11-C15) of phorboxazole A.
The synthesis used a convergent approach involving...
The potent antitumor agent phorboxazole A was synthesized from six subunits comprising C1-C2 (115), C3-C8 (98), C9-C19 (74), C20-C32 (52), C33-C41 (84) and C42-C46 (85). Tetrahydropyrans B and C containing cis-2,6-disubstitution were fabricated via palladium(II)-mediated intramolecular alkoxycarbonylation which, in the case of tetrahydropyran C, was carried out with catalytic palladium(II)...
Drilled shaft foundation elements provide a cost-effective foundation alternative for the support of building and bridge superstructure loads. Bi-directional pile loading tests (BDPLTs) to evaluate the capacity of drilled shafts have become popular owing to their capacity to save time and effort as compared to the use of top-down loading...
Performance-based design has gained interest in recent years among structural designers and researchers. Performance-based design includes selection of appropriate building sites, structural systems and configurations, as well as analytical procedures used in the design process, to confirm that the structure has adequate strength, stiffness and energy dissipation capacity to respond...
A two-dimensional numerical mesoscale model, which ic1udes
radiative and turbulent transfers, has been constructed to study the
formation, development and dissipation of coastal stratus cloud
under an inversion. In the model, the delta-Eddington and emissivity
approximations are used for the solar and thermal radiative
transfers, respectively. K-theory parameterization is adopted...
The relationships between types of wealth components and consumption
expenditures were investigated as a means of better understanding retired
elderly household well-being. Specifically, the concept of mental account was
used to identify the characteristics of different types of wealth components, and
four mental accounts were identified: flow of investment, current...
As microelectronic parts trend smaller so do their solder joints. The surface finish on a copper pad is expected to become a significant part of the total solder joint volume and therefore affect mechanical properties of the smaller solder joints. Two sample geometries and four different surface finishes for tin-silver-copper...
A complete solution, exact to second-order, for wave motion
forced by a hinged-wavemaker of variable-draft is presented. A
solution for a piston type wavemaker is also obtained as a special
case of a hinged-wavemaker with negative infinite draft. The
existing Stokes inviscid theories for mass transport is extended to
include...
The purpose of this study was to design and to implement
a practical Ethernet Local Area Network (LAN)
board for the Macintosh II computer system. A survey
of the literature provided a general definition of
LANs, a reference model for network layers, specifications
for an Ethernet LAN, and information on...
The objective of this study is the development and
verification of an analytical solution for an unsteady
flow field partially occupied by a permeable structure.
Flow is induced by a small amplitude incident wave
train and the permeable structure may contain multilayered
anisotropic but homogeneous material. The analytical
solution developed...
This study evaluates the prediction of heat and moisture fluxes from a new land surface scheme with eddy correlation data collected at the old aspen site during the Boreal Ecosystem-Atmosphere Study (BOREAS) in 1994. The model used in this study couples a multilayer vegetation model with a soil model. Inclusion...
Due to its high strength/weight ratio, 7075 aluminum alloy has
been widely used as an aerospace material. However, it has relatively low fatigue strength and low fracture toughness in the T6
condition. Thermomechanical processing, including pre-cyclic loading and stretching at high and ambient temperatures, has been investigated with the aim...
The 1,1-dichloroethene (1,1-DCE) cometabolic transformation abilities of indigenous and bioaugmented microorganisms were compared in microcosms constructed with groundwater and aquifer solids from the Moffett Field site, CA. Microbial community structure in the microcosms and possible community shifts due to 1,1-DCE transformation stress was evaluated by terminal restriction fragment length polymorphism...
The research undertaken in this study deals with three topics related to the prediction of thermodynamic properties of electrolytes in aqueous solutions. In the first, Pitzer ion interaction parameters for 304 single electrolytes were evaluated from recently published osmotic coefficient data at 25°C by using multiple regression analysis to fit...
Bacterial histamine formation in mackerel and albacore was studied by inducing histamine in the muscles under controlled storage conditions. The optimum temperature for histamine formation was 25°C. The highest level of histamine detected was 283 mg/100 g in the 2-day stored mackerel; and 67.1 mg/100 g in the 6-day stored...
New transparent p- and n-type semiconductors and luminescent materials have been prepared and characterized. Synthesis, structures, optical and electrical properties of new chalcogenide fluoride p-type transparent semiconductors MCuQF (M=Ba, Sr; Q=S, Se, Te) are described. Band-gap tuning and improvement in conductivity through p-type doping are demonstrated in the family. The...