Biomimetic polymers of plant cutin: an approach from molecular modeling.

Biomimetics of materials is based on adopting and reproducing a model in nature with a well-defined functionality optimized through evolution. An example is barrier polymers that protect living tissues from the environment. The protecting layer of fruits, leaves, and non-lignified stems is the plant cuticle.

Molecular modification of coumarin dyes for more efficient dye sensitized solar cells.

In this work, new coumarin based dyes for dye sensitized solar cells (DSSC) have been designed by introducing several substituent groups in different positions of the NKX-2311 structure. Two types of substitutions have been considered: the introduction of three electron-donating groups (-OH, -NH(2), and -OCH(3)) and two different substituents with steric effect: -CH(2)-CH(2)-CH(2)- and -CH(2)-HC=CH-. The electronic absorption spectra (position and width of the first band and absorption threshold) and the position of the LUMO level related to the conduction band have been used as theoretical criteria to evaluate the efficiency of the new dyes.

Coumarin derivatives for dye sensitized solar cells: a TD-DFT study.

Time dependent density functional theory (TD-DFT) calculations have been carried out to study the electronic structure and the optical properties of five coumarin based dyes: C343, NKX-2311, NKX-2586, NKX-2753 and NKX-2593. We have found out that the position and width of the first band in the electronic absorption spectra, the absorption threshold and the LUMO energy with respect to the conduction band edge are key parameters in order to establish some criteria that allow evaluating the efficiency of coumarin derivatives as sensitizers in Dye Sensitized Solar Cells (DSSC). Those criteria predict the efficiency ordering for the coumarin series in good agreement with the experimental evidence.

V@Au12-: an improved novel catalyst for CO oxidation?

The catalytic properties toward CO combustion of an encapsulated cluster, V@Au12-, have been explored by means of plane-wave pseudopotential density-functional theory calculations. Single adsorption of both O2 and CO as well as coadsorption have been considered. The adsorption energy for the O2 molecule is about 0.

Gastric outlet obstruction as a consequence of a duodenal web masquerading as gastrinoma in an adult.

We present the case of a 24-year-old man with recurrent peptic ulcers and hypergastrinemia, in whom a multidisciplinary investigation for gastrinoma revealed a duodenal web. The affected duodenal segment was excised, and a gastroduodenostomy with highly selective vagotomy was performed. Postoperative serum gastrin levels returned to the normal range over the next 6 weeks.

Gastroprotection by coxibs: what do the Celecoxib Long-Term Arthritis Safety Study and the Vioxx Gastrointestinal Outcomes Research Trial tell us?

Current evidence suggests that PPIs might be effective in maintaining patients in remission during continued NSAID use and that the combination of omeprazole plus diclofenac is as effective as treatment with celecoxib in preventing recurrent bleeding. Larger outcome studies comparing the combination of a PPI with other nonselective NSAIDs and a selective COX-2 inhibitor (and the combination of a selective COX-2 inhibitor with a PPI or misoprostol) are required to determine whether or not any regimen will further decrease or eliminate the risk of ulcer complications in high-risk individuals.

Colorectal cancer screening and familial risk: a survey of internal medicine residents' knowledge and practice patterns.

Objective: Risk stratification is essential to the appropriate use of colorectal cancer screening recommendations. The principal objective of this study was to assess the knowledge and screening behavior of internal medicine (IM) residents regarding familial colorectal cancer.

Methods: We conducted a survey of IM residents in their second and third year of postgraduate training from two university-based programs (n = 127).

Adsorption of Acetone onto MgO: Experimental and Theoretical Evidence for the Presence of a Surface Enolate.

A new band at 1640 cm is revealed by diffuse reflectance FT-IR spectroscopy of acetone adsorbed on a MgO surface (shown schematically). On the grounds of ab initio quantum-mechanical calculations, this band is assigned to an adsorbed enolate species. This evidence proves the catalytic role of the metal oxide surface in the condensation reaction mechanism.