Search results for "DIOXIDE"

Exposure to ambient air pollution during pregnancy and preterm birth: A Spanish multicenter birth cohort study

2016

Background and objective: Preterm birth is a major determinant of infant mortality and morbidity. Air pollution has been suggested as a risk factor for preterm delivery; however, the scientific evidence on this impact remains inconsistent. We assessed the association between residential exposure to air pollution during pregnancy and preterm birth (gestational age at delivery <37 weeks) in Spain. Methods: This study was based on 2409 pregnant women participating in the INMA birth cohorts in Asturias, Gipuzkoa, Sabadell and Valencia. Ambient levels of nitrogen dioxide (NO2) and benzene were estimated for each woman's residence for each trimester and for the whole pregnancy, using temporally a…

Social factors associated with nitrogen dioxide (NO2) exposure during pregnancy: The INMA-Valencia project in Spain

2011

Numerous studies have focused on the effects of exposure to air pollution on health: however, certain subsets of the population tend to be more exposed to such pollutants depending on their social or demographic characteristics. In addition, exposure to toxicants during pregnancy may play a deleterious role in fetal development as fetuses are especially vulnerable to external insults. The present study was carried out within the framework of the INMA (Infancia y Medio Ambiente or Childhood and the Environment) multicenter cohort study with the objective of identifying the social, demographic, and lifestyle factors associated with nitrogen dioxide (NO2) exposure in the subjects in the cohort…

Preterm birth and exposure to air pollutants during pregnancy.

2010

Background Research has shown that prenatal exposure to air pollutants may have a detrimental effect on fetal development with the strength of the relationship depending on the effect being studied The evidence to date however is insufficient to establish a direct causal link between such exposure and preterm delivery This study evaluates the specific effect of prenatal exposure to NO2 and benzene on preterm births Methods The population under study comprised 785 pregnant women who formed part of the INMA cohort in Valencia Spain (2003-2005) Multiple regression models were used for mapping outdoor nitrogen dioxide (NO2) and benzene levels throughout the area Individual exposure was assigned…

Enhanced Role of Transition Metal Ion Catalysis During In-Cloud Oxidation of SO2

2013

Global sulfate production plays a key role in aerosol radiative forcing; more than half of this production occurs in clouds. We found that sulfur dioxide oxidation catalyzed by natural transition metal ions is the dominant in-cloud oxidation pathway. The pathway was observed to occur primarily on coarse mineral dust, so the sulfate produced will have a short lifetime and little direct or indirect climatic effect. Taking this into account will lead to large changes in estimates of the magnitude and spatial distribution of aerosol forcing. Therefore, this oxidation pathway-which is currently included in only one of the 12 major global climate models-will have a significant impact on assessmen…

Energy efficiency in Spanish wastewater treatment plants: a non-radial DEA approach.

2011

Wastewater treatment plants (WWTPs) are energy-intensive facilities. Thus, reducing their carbon footprint is particularly important, both economically and environmentally. Knowing the real operating energy efficiency of WWTPs is the starting point for any energy-saving initiative. In this article, we applied a non-radial Data Envelopment Analysis (DEA) methodology to calculate energy efficiency indices for sampling of WWTPs located in Spain. In a second stage analysis, we examined the operating variables contributing to differences in energy efficiency among plants. It is verified that energy efficiencies of the analyzed WWTPs were quite low, with only 10% of them being efficient. We found…

Atmospheric protein chemistry influenced by anthropogenic air pollutants: nitration and oligomerization upon exposure to ozone and nitrogen dioxide

2017

The allergenic potential of airborne proteins may be enhanced via post-translational modification induced by air pollutants like ozone (O3) and nitrogen dioxide (NO2). The molecular mechanisms and kinetics of the chemical modifications that enhance the allergenicity of proteins, however, are still not fully understood. Here, protein tyrosine nitration and oligomerization upon simultaneous exposure of O3 and NO2 were studied in coated-wall flow-tube and bulk solution experiments under varying atmospherically relevant conditions (5–200 ppb O3, 5–200 ppb NO2, 45–96% RH), using bovine serum albumin as a model protein. Generally, more tyrosine residues were found to react via the nitration pathw…

Functionalization of CnH2n+2Alkanes: Supercritical Carbon Dioxide Enhances the Reactivity towards Primary Carbon-Hydrogen Bonds

2015

The functionalization of the primary sites of alkanes is one of the more challenging areas in catalysis. In this context, a novel effect has been discovered that is responsible for an enhancement in the reactivity of the primary C-H bonds of alkanes in a catalytic system. The copper complex Cu(NCMe) (=hydrotris{[3,5-bis(trifluoromethyl)-4-bromo]-pyrazol-1-yl}borate) catalyzes the functionalization of CnH2n+2 with ethyl diazoacetate upon inserting the CHCO2Et unit into C-H bonds. In addition, the selectivity of the reaction toward the primary sites significantly increased relative to that obtained in neat alkane upon using supercritical carbon dioxide as the reaction medium. This was attribu…

Favoring alkane primary carbon-hydrogen bond functionalization in supercritical carbon dioxide as reaction medium

2019

The selectivity of a catalytic alkane functionalization process can be modified just changing the reaction medium from neat alkane to supercritical carbon dioxide (scCO2). A silica supported copper complex bearing an Nheterocyclic carbene ligand promotes the functionalization of carbon-hydrogen bonds of alkanes by transferring the CHCO2Et group from N2=CHCO2Et (ethyl diazoacetate, EDA). In neat hexane only 3% of the primary C-H bonds (ethyl heptanoate being the product) are functionalized in that manner, whereas the same reaction carried out in scCO2 provides a 30% yield in this linear ester. Such effect seems to be induced by an electronic density flux from the NHC ligand to the surroundin…

Visible Light Induced Sulfoxidation of Alkanes in the Presence of Titania

2012

The Effect of Electronic Properties of Anodized and Hard Anodized Ti and Ti6Al4V on Their Reactivity in Simulated Body Fluid

2022

The electronic properties of barrier and porous layers on Ti and Ti6Al4V were studied. Barrier anodic oxides grown to 40 V on Ti and on Ti6Al4V are both n-type semiconductors with a band gap of 3.3 eV and 3.4 eV respectively, in agreement with the formation of amorphous TiO2. Anodizing to 200 V at 20 mA cm−2 in calcium acetate and β-glycerol phosphate disodium pentahydrate leads to the formation of Ca and P containing porous films with a photoelectrochemical behaviour dependent on the metallic substrate. A band gap of 3.2 eV and the flat band potential of −0.5 V vs Ag/AgCl were measured for the porous oxide on Ti, while optical transitions at 2.15 eV and a significantly more positive flat b…