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Biochar has been used as an amendment for disturbed soils. However, the changes of the rhizobacterial community after the biochar addition in mine soils, has not yet been elucidated. The aim of this study was to evaluate the response in the rhizobacterial communities of Brachiaria decumbens during different reclamation processes of coal mining using biochar. Five treatments were carried out: control, mine soil + biochar, mine soil + biochar + Azospirillum brasilense, mine soil + biochar + arbuscular mycorrhizal fungal + Mortierella sp. DNA from the rhizospheric soil was sequenced by Ion Torrent. The relative abundance in each sample was calculated. The Proteobacteria (70%) and Actinobacteria (23%) phyla dominated the rhizobacterial community composition during the establishment time. Seven months after seeding, Actinobacteria decreased significantly, while Proteobacteria increased. The Acidobacteria phylum was higher in the control. There was a higher abundance of Proteobacteria with the biochar treatments than for the control, thus the baseline for the rhizobacterial community changes induced by biochar was provided. The alpha diversity index showed the effect of biochar on the diversity and dominance of the rhizobacterial communities. The hierarchical clustering tree showed a correlation between the treatments with biochar, and a significant differentiation between these and the control treatment.

The ambient air of the Monterrey Metropolitan Area (MMA) in Mexico frequently exhibits high levels of PM10 and PM2.5. However, no information exists on the chemical composition of coarse particles ...

Anomalous origin of one of the pulmonary arteries from the aorta is unusual. The reported morbidity and mortality is mostly due to early onset vascular disease. Early surgical intervention has significantly improved outcomes. The diagnosis of this abnormality is challenging. The nomenclature used is inconsistent. Familiarity with this abnormality and consistent use of definitions and classifications is mandatory. An attempt is made to clarify misleading inconsistencies. An older ontogenetic theory is revisited.

Few studies have been made regarding carbonyl concentrations in Monterrey, México. The Monterrey Metropolitan Area (MMA) has the third largest population in the country and has increasing pollution issues. The concentrations of 10 aldehydes and two ketones were measured in the MMA, in the spring and fall of 2011 and 2012. Formaldehyde (16-42 ppbv) was the most abundant carbonyl, followed by acetaldehyde (5-15 ppbv) and acetone (7-15 ppbv). The concentrations showed marked diurnal trends with maximum values between 10:00 a.m. and 2:00 p.m., when photochemical activity is intense. Thus, secondary production of carbonyls is statistically significant in the city. Biogenic production of several carbonyls, such as 2-butanone, was supported by their mid correlation with solar radiation and low correlation with propionaldehyde, which is mainly emitted by anthropogenic sources. The seasonal variability of the concentrations was observed in the first three samplings, with the highest levels reached in the fall. The rainy conditions during the fourth sampling did not allow comparison. Carbonyl-NOx-O3 analysis was made. Results indicated a carbonyl-sensitive atmosphere, especially during the midday samplings of 10:00 a. m. to 2:00 p.m. and 2:00 p.m. and 6:00 p.m. because of the intense solar radiation during these periods.Monitoring of carbonyls in Monterrey, Mexico, was performed to quantify the pollutant concentration in the city's atmosphere. Although primary emission is significantly important, the secondary production of the pollutants, along with ozone production being carbonyl sensitive, indicates that air pollution controls must address the direct sources and the precursors of the pollutants to achieve air quality.

This paper presents a smooth control strategy for the regulation problem of an uncertain system, which assures uniform ultimate boundedness of the closed-loop system inside of the zero-state neighbourhood. This neighbourhood can be made arbitrarily small. To this end, a class of nonlinear proportional integral controllers or PI controllers was designed. The behaviour of this controller emulates very close a sliding mode controller. To accomplish this behaviour saturation functions were combined with traditional PI controller. The controller did not need a high-gain controller or a sliding mode controller to accomplish robustness against unmodelled persistent perturbations. The obtained closed-solution has a finite time of convergence in a small vicinity. The corresponding stability convergence analysis was done applying the traditional Lyapunov method. Numerical simulations were carried out to assess the effectiveness of the obtained controller.

A summer episode was modeled to address the expected response of ambient air O3 to hypothetical emission control scenarios in northeastern Mexico, and in particular in the Monterrey Metropolitan Area (MMA). This region is of interest because the MMA holds one of the worst air quality problems in the country and levels of air pollutants in the rest of northeastern Mexico are starting to be a concern. The MM5-SMOKE-CMAQ platform was used to conduct the numerical experiments. Twenty-four control scenarios were evaluated, combining the level of emission controls of O3 precursors (NO(x) and volatile organic compounds [VOCs]) from 0% to 50%. For the MMA, VOC-only controls result in the best option to reduce O3 concentrations, though the benefit is limited to the urban core. This same strategy results in negligible benefits for the rest of northeastern Mexico. NO(x) controls result in an increase in O3 concentration within the MMA of up to 20 ppbv and a decrease at downwind locations of up to 11 ppbv, with respect to the base-case scenario. Indicator ratios were also used to probe for NO(x)-sensitive and VOC-sensitive areas. Locations with an important influence of NO(x) point sources (i.e., Monclova and Nava/Acuña) are quite sensitive to changes in NO(x) emissions. Border cities in the Rio Bravo/Grande Valley tend to be marginally NO(x)-sensitive. Overall, the MMA seems to be dominated by a VOC-sensitive regime, while the rest of the region would tend to have a NO(x)-sensitive response. The results obtained serve to expand the current knowledge on the chemical regimes that dominate this region (VOC- or NO(x)-sensitive), and thus could help guide public policies related to emission regional control strategies.

The Monterrey Metropolitan Area (MMA) has shown a high concentration of PM2.5 in its atmosphere since 2003. The contribution of possible sources of primary PM2.5 and its precursors is not known. In this paper we present the results of analyzing the chemical composition of sixty 24-hr samples of PM2.5 to determine possible sources of PM2.5 in the MMA. The samples were collected at the northeast and southeast of the MMA between November 22 and December 12, 2007, using low-volume devices. Teflon and quartz filters were used to collect the samples. The concentrations of 16 airborne trace elements were determined using x-ray fluorescence (XRF). Anions and cations were determined using ion chromatography. Organic carbon (OC) and elemental carbon (EC) were determined by thermal optical analysis. The results show that Ca had the maximum mean concentration of all elements studied, followed by S. Enrichment factors above 50 were calculated for S, Cl, Cu, Zn, Br and Pb. This indicates that these elements may come from anthropogenic sources. Overall, the major average components of PM2.5 were OC (41.7%), SO4(2-) (22.9%), EC (7.4%), crustal material (11.4%), and NO3- (12.6%), which altogether accounted for 96% of the mass. Statistically, we did not find any difference in SO4(2-) concentrations between the two sites. The fraction of secondary organic carbon was between 24% and 34%. The results of the factor analysis performed over 10 metals and OC and EC show that there are three main sources of PM2.5: crustal material and vehicle exhaust; industrial activity; and fuel oil burning. The results show that SO4(2-), OC, and crustal material are important components of PM2.5 in MMA. Further work is necessary to evaluate the proportion of secondary inorganic and organic aerosol in order to have a better understanding of the sources and precursors of aerosols in the MMA.

The airshed shared by the Valley of Mexicali in Mexico and Imperial Valley in the United States frequently experiences high levels of particulate matter (PM) less than 10 microm (PM10). However, very little information exists on the concentration and composition of fine PM (PM2.5 microm, or PM2.5) in the region, particularly on the Mexican side of the border. This paper presents the results of two monitoring campaigns (November 23-December 17, 2004 and April 12-22, 2005) that were conducted to obtain, for the first time, detailed composition of PM2.5 in the city of Mexicali. In both campaigns, 24-hr average PM2.5 samples were collected using low-volume equipment. Samples collected on Teflon filters were analyzed for mass and 38 metals (Na to Pb), whereas samples collected on quartz filters were analyzed for anions (sodium, potassium, ammonium), cations (chloride, nitrate, sulfate), and carbon (organic [OC] and elemental [EC]). During the fall campaign, the monitored concentration exceeded 65 microg/m3 (i.e., Mexico's PM2.5 air quality standard for 24-hr average samples) on four different days at one or more Mexicali sites. No exceedances were reported during the spring campaign. The contribution of main chemical species to the total mass indicated that organic material was the principal component (62% in fall and 56% in spring). Average secondary OC contributions to the total observed OC for the fall data was estimated at 14% (no day exceeding 30% contribution) and 47% for the spring data (with the minimum being 33% and the maximum 68%). Ammonium sulfate contributions exceeded ammonium nitrate contributions during the spring (16% vs. 7%), whereas the reverse occurred during the fall (5% vs. 10%). Geological material contributed 6% of the mass in the fall versus 10% in the spring. Overall the results indicate that PM2.5 in Mexicali is heavily influenced by anthropogenic sources, rather than from soil resuspension. Spatial and meteorological analysis of the data gives an indication that during the fall campaign local sources were the principal contributor to high-PM events, whereas during the spring campaign regional sources from southern California could have also contributed to the observed PM2.5 levels.

A high performance liquid chromatography (HPLC) method for the estimation of pravastatin in human serum samples has been developed to monitor dyslipidemic patients. The method was fully validated and validation parameters were in the linearity range 10–200 ng/mL, correlation coefficient 0.99, mean recovery >0.73, quantification limit 10 ng/mL, and limit of detection, 5 ng/mL; this method was applied for pravastatin determination in human serum from Mexican dyslipidemic patients. Pravastatin values found for three studied patients were 73, 57, and

A high performance liquid chromatography method for estimation of pravastatin in tablets has been developed. The mobile phase consisted of acetonitrile and phosphates buffer in a volume percentage ratio of 7:3 v/v, pH 2.0 and was delivered at the rate of 1 mL/min and detected at 238 nm, retention times were approximately 7.3 min: this peak was analyzed with mass spectroscopy. The method was fully validated and validation parameters were: linearity range 10–200 ng/mL, correlation coefficient 0.999, mean recovery >99%, limit of quantification 5 ng/mL, and limit of detection 5 ng/mL; this method can be used for a quality control assay.

Resumen A polymerase chain reaction (PCR) was applied to detect genetically modified (GM) maize and soybean food product, using specific 35S promoter primers for inserted chimerical genes in maize or soybean. The PCR detected food products that include ingredients obtained from GMOs in maize grains and flour, as well as processed in foods such as tortillas (Mexican crepe), corn chips, corn and soybean oils. Beside the promoter, the PCR also detected zeine and lectin genes for maize and soybean, respectively, which confirmed the identity of the analyzed samples. The presence of transgenic material was also confirmed by detecting the terminator Tnos region. High quality DNA from samples permitted an accurate detection of GM in food products while low quality DNA could lead to false negatives. The event Bt-176 and non-GM maize were used as positive and negative controls, respectively. Three types of GM food-products (grain, flour and soybean oil) resulted positive, while flour products (tortilla and...

Three-dimensional air quality models (AQMs) represent the most powerful tool to follow the dynamics of air pollutants at urban and regional scales. Current AQMs can account for the complex interactions between gas-phase chemistry, aerosol growth, cloud and scavenging processes, and transport. However, errors in model applications still exist due in part to limitations in the models themselves and in part to uncertainties in model inputs. Four-dimensional data assimilation (FDDA) can be used as a top-down tool to validate several of the model inputs, including emissions inventories, based on ambient measurements. Previously, this FDDA technique was used to estimate adjustments in the strength and composition of emissions of gas-phase primary species and O3 precursors. In this paper, we present an extension to the FDDA technique to incorporate the analysis of particulate matter (PM) and its precursors. The FDDA approach consists of an iterative optimization procedure in which an AQM is coupled to an inverse model, and adjusting the emissions minimizes the difference between ambient measurements and model-derived concentrations. Here, the FDDA technique was applied to two episodes, with the modeling domain covering the eastern United States, to derive emission adjustments of domainwide sources of NO., volatile organic compounds (VOCs), CO, SO2, NH3, and fine organic aerosol emissions. Ambient measurements used include gas-phase inorganic and organic species and speciated fine PM. Results for the base-case inventories used here indicate that emissions of SO2 and CO appear to be estimated reasonably well (requiring minor revisions), while emissions of NOx, VOC, NH3, and organic PM with aerodynamic diameter less than 2.5 microm (PM2.5) require more significant revision.