No abstract

The adhesion of vapor deposited Au and Pt thin fi lms onto poly(methyl methacrylate) (PMMA) substrates can be signifi cantly enhanced by either spin-casting or vapor-exposure to hydrohalocarbon solvents prior to metal deposition. X-ray photoelectron spectroscopy (XPS) and evolved gas analysis Fourier transform infrared spectroscopy detect residual halogenated solvent at the PMMA surface which chemically activates the surface. Density functional theory (DFT) calculations show that the solvent molecules form a Lewis acid-base adduct with the ester oxygens in PMMA. DFT predicts that the deposited metal atom (M) inserts into the C-halogen (X) bond on either CHCl 3 or CHBr 3 to form a O-M-X interaction. This is consistent with M-X bonding observed in high resolution XPS. A model is proposed in which the bond energy of the C-X bond of the solvent must be weak enough so that it can be cleaved by the metal atom to form a M-X bond. A negative control of PMMA exposed to CHF 3 is shown to have no effect on Au or Pt adhesion since the bond dissociation energy of the C-F bond is stronger than the C-Cl and C-Br bond energy compared to the metal halide bond energies.

No abstract

Neuroendocrine neoplasms are most often found in the small intestine, rectum, appendix, and stomach. The colon, excluding the appendix and the cecum, is a rare location for these neoplasms and often gives rise to highly proliferative, poorly differentiated tumors with aggressive features and dismal prognosis. A 32-year-old male presents with a large cell neuroendocrine carcinoma arising from an unusual location, the descending colon. The patient's clinical and imaging characteristics resembles those seen in the much more common neoplasm, colonic adenocarcinoma. Computed tomography and In-111 octreotide scan are limited in diagnosing large cell neuroendocrine carcinoma. Pathologic correlation of a surgical specimen is required to make the correct diagnosis.