Now showing items 51-60 of 77
Influence of rice field agrochemicals on the ecological status of a tropical stream
Many tropical countries contain a high density of protected ecosystems, and these may often be bordered by intensive agricultural systems. We investigated the chemical and ecological status of a stream connecting an area ...
Metals in coastal mollusks of Costa Rica
Metales en moluscos costeros de Costa Rica
The input of contaminants to coastal ecosystems is a global problem on the rise. Data on metal pollution from tropical sites is often lacking and pilot surveys are urgently needed to provide a general framework to estimate ...
Granular Activated Carbon Treatment May Result in Higher Predicted Genotoxicity in the Presence of Bromide
Certain unregulated disinfection byproducts (DBPs) are more of a health concern than regulated DBPs. Brominated species are typically more cytotoxic and genotoxic than their chlorinated analogs. The impact of granular ...
Removal of N-nitrosodimethylamine precursors with powdered activated carbon adsorption
The main objective of this study was to examine the roles of powdered activated carbon (PAC) characteristics (i.e., surface chemistry, pore size distribution, and surface area) in the removal of N-nitrosodimethylamine ...
A Metabolic Widget Adjusts the Phosphoenolpyruvate-Dependent Fructose Influx in Pseudomonas putida
Fructose uptake in the soil bacterium Pseudomonas putida occurs through a canonical phosphoenolpyruvate (PEP)-dependent sugar transport system (PTSFru). The logic of the genetic circuit that rules its functioning is puzzling: ...
Detection of the adsorption of water monolayers through the ion oscillation frequency in the magnesium oxide lattice by means of low energy electron diffraction
We investigate the variation of the oscillation frequency of the Mg2+ and O2− ions in the magnesium oxide lattice due to the interactions of the surface with water monolayers by means of Low Energy Electron Diffraction. ...
Room temperature gas-solid reaction of titanium on glass surfaces forming a very low resistivity layer
Titanium films were deposited on quartz, glass, polyamide and PET substrates in a high vacuum system at room temperature and their electrical resistance monitored in vacuo as a function of thickness. These measurements ...
Caracterización fisicoquímica de las aguas superficiales de la cuenca del río Rincón en la Península de Osa, Puntarenas, Costa Rica
(San Pedro de Montes de Oca, San José, Costa Rica, 2008)
Este proyecto se desarrolló en la cuenca del río Rincón en la península de Osa, una de las regiones geológicas más antiguas de Costa Rica. En ella afloran unidades de roca ígnea y sedimentaria, además de sedimentos ...
Organic Acids without a Carboxylic Acid Functional Group
(Journal of Chemical Education 77(7):910-915. July 2000, 2000-07)
This paper presents several organic molecules that have been labeled as acids but do not contain a carboxylic acid functional group. The rationale for the nomenclature and appropriate explanations for the apparent acidity ...
Fisico-química de las aguas superficiales de la Cuenca del río Rincón, Península de Osa, Costa Rica
Hydrochemistry of the surface waters at the Rincon River Basin, Osa Peninsula, Costa Rica
The Rincon River Basin is characterized by steep and rugged topography with outcrops of recent sediments as well as igneous and sedimentary rocks. The area is mostly covered by forest (Tropical Wet Forest) and agricultural ...