An Analytical Method for Detecting Toxic Metal Cations Using Cyclotriveratrylene Derivative Capped Gold Nanoparticles

Cyclotriveratrylene-oxime (CTV-oxime) derivatives that terminate with a dithiolate linker were synthesized enabling the supramolecular scaffold to adhere to gold nanoparticles (AuNPs) with the bowl-shaped cavity of the CTV scaffold exposed for utilization in host–guest chemistry. Exposure of these CTV functionalized AuNPs to varying concentrations of di- and trivalent metal cations resulted in the formation of large CTV-AuNP polymeric clusters and an accompanying a shift in the plasmon resonance. These interactions between the CTV-AuNPs and the metal cations in solution provides proof-of-concept that supramolecular functionalized AuNPs can be used as a simple and straightforward, on-site detection system for toxic metal cations in solution. The order of binding affinity of the metals studied based on observed Kd values is Cu2+ \u3e Zn2+ \u3e Pb2+ \u3e Hg2+ \u3e Eu3+ \u3e Cd2+

A hydrogeomorphic approach to evaluating flood potential in central Texas from orbital and suborbital remote sensing imagery

There are no author-identified significant results in this report

Development and Application of Operational Techniques for the Inventory and Monitoring of Resources and Uses for the Texas Coastal Zone

The author has identified the followed significant results. Techniques for interpretation of LANDSAT images were developed, along with a modified land use classification scheme

Direct Patterning of a Cyclotriveratrylene Derivative for Directed Self-assembly of C60

A novel apex-modified cyclotriveratrylene (CTV) derivative with an attached thiolane-containing lipoic acid linker was directly patterned onto gold substrates via dip-pen nanolithography (DPN). The addition of a dithiolane-containing linker to the apex of CTV provides a molecule that can adhere to a gold surface with its bowl-shaped cavity directed away from the surface, thereby providing a surface-bound CTV host that can be used for the directed assembly of guest molecules. Subsequent exposure of these CTV microarrays to C60 in toluene resulted in the directed assembly of predesigned, spatially controlled, high-density microarrays of C60. The molecular recognition capabilities of this CTV template toward C60 provides proof-of-concept that supramolecular CTV scaffolds can be directly patterned onto surfaces providing a foundation for the development of organic electronic and optoelectronic materials

Barium and Calcium Stimulate Secretion from Digitonin-Permeabilized Bovine Adrenal Chromaffin Cells by Similar Pathways

We compared the characteristics of secretion stimulated by EGTA-buffered Ba 2+ - and Ca 2+ -containing solutions in digitonin-permeabilized bovine adrenal chromaffin cells. Half-maximal secretion occurred at approximately 100 Μ M Ba 2+ or 1 Μ M Ca 2+ . Ba 2+ -stimulated release was not due to release of sequestered intracellular Ca 2+ because at a constant free Ba 2+ concentration, increasing unbound EGTA did not diminish the extent of release due to Ba 2+ . The maximal extents of Ba 2+ - and Ca 2+ -dependent secretion in the absence of MgATP were identical. MgATP enhanced Ba 2+ -induced secretion to a lesser extent than Ca 2+ -induced secretion. Half-maximal concentrations of Ba 2+ and Ca 2+ , when added together to cells, yielded approximately additive amounts of secretion. Maximal concentrations of Ba 2+ and Ca 2+ when added together to cells for 2 or 15 min were not additive. Tetanus toxin inhibited Ba 2+ - and Ca 2+ -dependent secretion to a similar extent. Ba 2+ , unlike Ca 2+ , did not activate polyphosphoinositide-specific phospholipase C. These data indicate that (1) Ba 2+ directly stimulates exocytosis, (2) Ba 2+ -induced secretion is stimulated to a lesser extent than Ca 2+ -dependent secretion by MgATP, (3) Ba 2+ and Ca 2+ use similar pathways to trigger exocytosis, and (4) exocytosis from permeabilized cells does not require activation of polyphosphoinositide-specific phospholipase C.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66323/1/j.1471-4159.1992.tb09771.x.pd

Magnetic domain walls in constrained geometries

Magnetic domain walls have been studied in micrometer-sized Fe20Ni80 elements containing geometrical constrictions by spin-polarized scanning electron microscopy and numerical simulations. By controlling the constriction dimensions, the wall width can be tailored and the wall type modified. In particular, the width of a 180 degree Neel wall can be strongly reduced or increased by the constriction geometry compared with the wall in unconstrained systems.Comment: 4 pages, 6 figure

Stream network analysis and geomorphic flood plain mapping from orbital and suborbital remote sensing imagery application to flood hazard studies in central Texas

The author has identified the following significant results. Development of a quantitative hydrogeomorphic approach to flood hazard evaluation was hindered by (1) problems of resolution and definition of the morphometric parameters which have hydrologic significance, and (2) mechanical difficulties in creating the necessary volume of data for meaningful analysis. Measures of network resolution such as drainage density and basin Shreve magnitude indicated that large scale topographic maps offered greater resolution than small scale suborbital imagery and orbital imagery. The disparity in network resolution capabilities between orbital and suborbital imagery formats depends on factors such as rock type, vegetation, and land use. The problem of morphometric data analysis was approached by developing a computer-assisted method for network analysis. The system allows rapid identification of network properties which can then be related to measures of flood response