Use of short monolithic columns for isolation of low abundance membrane proteins

Convective interaction media (CIM) monoliths provide a stationary phase with a high binding capacity for large molecules and are capable of high flow rates at a very low pressure drop. Used as anion- and cation-exchangers or with affinity ligands such as antibodies, these columns have the potential for processing large volumes of complex biological mixtures within a short time. In the present report, monoclonal antibodies against several rat liver plasma membrane proteins were bound and cross-linked to protein A or protein G CIM affinity columns with a bed volume of only 60 microL. Antigens recognized by bound antibodies and co-eluting (interacting) proteins were rapidly isolated in a single step from either total plasma membrane extracts or subfractions isolated using anion-exchange CIM disk-shaped columns. The isolated antigens and co-eluting proteins were subsequently identified by immunoblot or by LC-MS/MS.     

High-density arrays of InGaN nanorings, nanodots, and nanoarrows fabricated by a template-assisted approach

Dense, crystalline arrays of InGaN nanorings, nanodots, and nanoarrows have been fabricated on GaN substrates by template-assisted nano-area selective growth. To create the nanostructures, we have used nanoporous anodic alumina films as templates to pattern nanopores in an SiO2 transfer layer, and then used this patterned SiO2 layer as a template for nitride growth by metalorganic chemical vapor deposition. We have varied the diameter of the deposited nitride nanostructures from 35 to 250 nm by changing the initial anodic alumina template structure. In addition, by controlling the nitride growth time we have created various types of nanostructures, from nanorings to nanoarrows. This structural evolution begins with the nucleation and formation of a nanoring structure, followed by coalescence and growth to form faceted nanodots, and finally lateral overgrowth to form faceted nanoarrows.     

Four isomers from the oxidative addition of Me3SnH to Os(CO)2(PPh3)3 and the crystal structure of Os(SnMeI2)I(CO)2(PPh3)2, in which the pairs of CO and PPh3 ligands are mutually trans

Reaction between Os(CO)₂(PPh₃)₃ and Me₃SnH produces Os(SnMe₃)H(CO)₂(PPh₃)₂ (1). Multinuclear NMR studies of solutions of 1 reveal the presence of four geometrical isomers, the major one being that with mutually cis triphenylphosphine ligands and mutually trans CO ligands. Os(SnMe₃)H(CO)₂(PPh₃)₂ undergoes a redistribution reaction, at the trimethylstannyl ligand, when treated with Me₂SnCl₂ giving Os(SnMe₂Cl)H(CO)₂(PPh₃)₂ (2). Solutions of 2 again show the presence of four isomers but now the major isomer is that with mutually trans triphenylphosphine ligands and mutually cis CO ligands. The redistribution reaction of 1 with SnI₄ produces Os(SnMeI₂)H(CO)₂(PPh₃)₂ (3) which exists in solution as only one isomer, that with mutually trans triphenylphosphine ligands and mutually trans CO ligands. Treatment of 3 with I₂ cleaves the Os-H bond with retention of geometry giving Os(SnMeI₂)I(CO)₂(PPh₃)₂ (4). The crystal structure of 4 has been determined. No isomerization of the trans dicarbonyl complex 4 occurs when 4 is heated, instead there is a formal loss of “MeSnI” and formation of OsI₂(CO)₂(PPh₃)₂ (5).     

The validity of the long-wave approximation for solitary waves in fluid-filled elastic tubes

Studies of solitary waves commonly apply the long-wave approximation, which unnecessarily rigidifies the behavior of the tube, but permits the problem to be solved using certain approximate numerical techniques. In this study, an approach was developed where approximating the contribution of the axial strain as a linear function of the radial strain reduced the system of exact governing differential equations to a single equation of a single dependent variable. The approximated solution was found to agree with the exact solution to within 3%. This approach would be useful for considering more complex problems where the exact solution technique may not be reasonably applied.     

Cryogenic operation of submillimeter quasioptical mixers

We report here the first results obtained by cooling a submillimeter quasioptical mixer, utilizing a Schottky diode in a corner reflector mixer structure. Measurements have been carried out at a wavelength of 434 microns. The diode inverse slope parameter V_o at low current decreases by a factor of 3 upon cooling to 50 K while the minimum system noise temperature of 5600 K (SSB), including the IF contribution, demonstrates a reduction of approximately 40% from the ambient temperature value. We also report improved system noise temperatures at 184 m and 119 m wavelengths of 38000 K and 64000 K (SSB), respectively.This work was supported by the Army Research Office and the Air Force Office of Scientific Research     

Crystal structure,physical and photophysical properties of a platinum(II) complex coordinated to the biphenyl dianion and cyclooctadiene

The complex, Pt(bph)(COD), where bph is the biphenyl dianion and COD is 1,5-cyclooctadiene, crystallizes in the orthorhombic space groupPbca witha=12.178(4) Å,b=9.693(3) Å andc=25.344(9) Å andZ=8. The Pt–C distances to the olefinic carbon atoms that result from the electron donation of the COD ligand are in the range 2.20(3)–2.27(3) Å and the Pt–C distances to the bonded bph ligand are shorter at 2.01(3)–2.03(2) Å. The lowest energy absorption of the complex is at 383 nm (=1.2×10³). The emission spectrum is structured in fluid solution at room temperature with the emission energy maximum at 537 nm, _cm, and =1.93 s. Temperature dependent emission lifetime measurements result in ak _o value of 2.69×10⁴, a preexponential factor of 2.47×10⁶ and a E₁ value of 324 cm^–1.     

11‐Methylpyrido[2,3‐b]acridine‐5,12‐dione

The title molecule, C₁₇H₁₀N₂O₂, is a synthetic precursor to the cytotoxic marine alkaloid ascididemin and is also structurally related to cleistopholine, a plant‐derived antifungal agent. The molecule was found to be essentially planar with the only significant deviations from planarity being for the quinone O atoms.