A ToF-SIMS and XPS study of protein adsorption and cell attachment across PEG-like plasma polymer films with lateral compositional gradients

In this work we report a detailed X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) study of poly(ethylene glycol) PEG-like chemical gradients deposited via plasma enhanced chemical vapour deposition (PECVD) at two different load powers using diethylene glycol dimethyl ether (DG) as a monomer. Principal component analysis (PCA) was applied to the ToF-SIMS data both before and after protein adsorption on the plasma polymer thin films. Results of the PCA loadings indicated a higher content of hydrocarbon fragments across the higher load power gradient, which adsorbed higher amounts of proteins. Gradients deposited at a lower load power retained a higher degree of monomer like functionality as did the central region directly underneath the knife edge electrode. Analysis of the adsorption of serum proteins (human serum albumin and fetal bovine serum) was monitored across the gradient films and increased with decreasing ether (PEG-like) film chemistries. The effect of protein incubation time on the levels adsorbed fetal bovine serum on the plasma polymer films was critical, with significantly more protein adsorbing after 24 hour incubation times on both gradient films. The attachment of HeLa cells on the gradients appeared to be dictated not only by the surface chemistry, but also by the adsorption of serum proteins. XPS analysis revealed that at surface ether concentrations of less than 70% in the gradient films, significant increases in protein and cell attachment were observed.     

Tri­benzyl(η5‐penta­methyl­cyclo­penta­dienyl)­hafnium(IV)

The title compound, [Hf(C₇H₇)₃(C₁₀H₁₅)], adopts a monomeric three‐legged piano‐stool structure. One benzyl ligand is disordered between two sites (44:56%) related by a ～30° rotation about an axis defined by the Hf atom and the ipso‐C atom of the benzyl ligand.     

Compression of amplified chirped optical pulses

We have demonstrated the amplification and subsequent recompression of optical chirped pulses. A system which produces 1.06 μm laser pulses widths of 2 ps and energies at the millijoule level is presented.     

Outpatient transoral laser vaporization of anterior glottic webs and keel placement: Risks of airway compromise

Management of acquired anterior glottic webs involves resection of the web with reconstitution of a linear vocal fold edge and anterior commissure. Traditional procedures such as transcervical midline thyrotomy (with tracheostomy) and keel placement have been used for patients with extensive scar formation and airway compromise. However, in selected patients with more limited scarring and minimal-to-no airway compromise, a transoral endoscopic approach may be a viable option. In three patients, transoral laser vaporization followed by transoral keel placement and outpatient removal resulted in a vocal quality that perceptually improved without any evidence of respiratory compromise postoperatively.     

Preparation and Structures of the 2.2.2-Cryptand(1+) Salts of the [Sb(2)Se(4)](2)(-), [As(2)S(4)](2)(-), [As(10)S(3)](2)(-), and [As(4)Se(6)](2)(-) Anions

2.2.2-Cryptand(1+) salts of the [Sb(2)Se(4)](2)(-), [As(2)S(4)](2)(-), [As(10)S(3)](2)(-), and [As(4)Se(6)](2)(-) anions have been synthesized from the reduction of binary chalcogenide compounds by K in NH(3)(l) in the presence of the alkali-metal-encapsulating ligand 2.2.2-cryptand (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane), followed by recrystallization from CH(3)CN. The [Sb(2)Se(4)](2)(-) anion, which has crystallographically imposed symmetry 2, consists of two discrete edge-sharing SbSe(3) pyramids with terminal Se atoms cis to each other. The Sb-Se(t) bond distance is 2.443(1) ?, whereas the Sb-Se(b) distance is 2.615(1) ? (t = terminal; b = bridge). The Se(b)-Sb-Se(t) angles range from 104.78(4) to 105.18(5) degrees, whereas the Se(b)-Sb-Se(b) angles are 88.09(4) and 88.99(4) degrees. The (77)Se NMR data for this anion in solution are consistent with its X-ray structure (delta 337 and 124 ppm, 1:1 intensity, -30 degrees C, CH(3)CN/CD(3)CN). Similar to this [Sb(2)Se(4)](2)(-) anion, the [As(2)S(4)](2)(-) anion consists of two discrete edge-sharing AsS(3) pyramidal units. The As-S(t) bond distances are 2.136(7) and 2.120(7) ?, whereas the As-S(b) distances range from 2.306(7) to 2.325(7) ?. The S(b)-As-S(t) angles range from 106.2(3) to 108.2(3) degrees, and the S(b)-As-S(b) angles are 88.3(2) and 88.9(2) degrees. The [As(10)S(3)](2)(-) anion has an 11-atom As(10)S center composed of six five-membered edge-sharing rings. One of the three waist positions is occupied by a S atom, and the other two waist positions feature As atoms with exocyclic S atoms attached, making each As atom in the structure three-coordinate. The As-As bond distances range from 2.388(3) to 2.474(3) ?. The As-S(t) bond distances are 2.181(5) and 2.175(4) ?, and the As-S(b) bond distance is 2.284(6) ?. The [As(4)Se(6)](2)(-) anion features two AsSe(3) units joined by Se-Se bonds with the two exocyclic Se atoms trans to each other. The average As-Se(t) bond distance is 2.273(2) ?, whereas the As-Se(b) bond distances range from 2.357(3) to 2.462(2) ?. The Se(b)-As-Se(t) angles range from 101.52(8) to 105.95(9) degrees, and the Se(b)-As-Se(b) angles range from 91.82(7) to 102.97(9) degrees. The (77)Se NMR data for this anion in solution are consistent with its X-ray structure (delta 564 and 317 ppm, 3:1 intensity, 25 degrees C, DMF/CD(3)CN).     

Measurements and simulations of high energy O(3P) + Ar(1S) angular scattering: single and multi-collision regimes

We present differential angular cross sections for O(3P) + Ar(1S) scattering at collision energies near 90 kcal mol(-1) (approximately 8 km s(-1) relative velocity) from molecular beam measurements and high-level theoretical calculations. Beams of hyperthermal O(3P) are now being used to investigate novel gas-phase and gas-surface chemistries, and the comparison of theory and measurements on this simple system will be a stringent test of the experimental methodology. Potential energy curves were generated for O(3P) + Ar(1S) using a large cc-pVQZ basis within a valence multi-configuration plus perturbation theory treatment. These curves were then used in quantum scattering calculations to generate differential cross sections. Agreement between experiment and theory is excellent. In addition to these comparisons, the cross sections were used in direct simulation Monte Carlo calculations to investigate effects of increasing the Ar flux above the "single-collision" regime. As the Ar flux increases, the observed differential angular cross sections change in two ways. In addition to the main "single-scatter" peak along the incident O-atom beam direction, a secondary O-atom peak appears in the direction of the incident Ar beam, and the multiple-scattered O-atom translational energy starts to reflect the energy of the relatively slow moving Ar beam.     

An approach to substituted 4-hydroxypyran-2-ones

We examined a method for the preparation of 4-hydroxypyran-2-ones in two steps from aryl ketones and ethyl malonyl chloride (or ethyl 2-methylmalonyl chloride). These 4-hydroxypyran-2-ones are useful precursors as they may be transformed in two steps to the 2-methoxypyran-4-ones, which is found in phenoxan—a naturally occurring compound discovered to have anti-HIV activity.