Environmental Geochemistry of Anthropogenic Lead in Estuarine Sediments of the Jamapa River, Mexico.

The combustion of alkyl-lead gasolines was the primary anthropogenic source of Pb in the second half of the twentieth century. Previously deposited Pb-aerosols enriched the organic matter and Fe-oxi-hydroxides phases of soils, which long after continue being transported downstream to be an important source of Pb into the ocean. Geochemical partition of Pb was determined in estuarine sediments of the Jamapa River, southern Gulf of Mexico, by the Tessier's sequential extraction protocol. The residual fraction, conformed by siliciclastic particles, contain the highest proportion of Pb (8.6 µg/g = 70%), been the main source into the ocean. However, as the organic carbon and Fe,MnO(OH) fractions, together summed the 26% of total Pb in samples, so, it is assumed that previously deposited anthropogenic Pb, from alkyl-lead gasolines, still is an important source of this element, that is transported by the Jamapa River, enriching the coastal area.

Distribution of the bioavailable and total content of copper and lead, in river sediments of the Jamapa-Atoyac fluvial system, Mexico.

The Jamapa-Atoyac fluvial system (JAFS) is tropical river system, which flows from the Pico de Orizaba, the highest elevation in Mexico, to end in the city of Veracruz, in the southern Gulf of Mexico. The geology of the watershed is dominated by Tertiary igneous rocks and Cretaceous limestones in the upper basin, and Quaternary alluvial sediments in the lower basin. Seventy percent of the land in the watershed has been deforested, and there are various urban and industrial areas. The JAFS is been widely known as source of trace elements to the coastal zone, and considered as contaminated. So, the aim of this study was to assess the environmental quality of the JAFS, using the total (TC) and the bioavailable (BF) concentrations of Cu and Pb, in surface fluvial sediments samples, in the dry (DS) and rainy (RS) seasons of the 2016. Average concentrations and ranges for the JAFS were CuT 10.2 ± 5.2 µg/g (2.2-41.5 µg/g); CuB 1.1 ± 1.4 µg/g (0.04-10.7 µg/g); PbT 5.0 ± 1.2 µg/g (1.8-10.9 µg/g); and PbB 0.7 ± 0.4 µg/g (0.1-2.0 µg/g). The BF only accounts for the ~ 10% of the total concentration for both elements, and is highly correlated to the mud content. No differences in average concentrations were found between the upper and lower bassins, nor among areas with different lithology. Cu presented higher concentrations during the RS, which suggest an enrichment of fluvial sediments from soil erosion, contrary, to Pb with higher concentrations during the DS. Although, some sampling stations, those located immediately after the Cordoba and Miguel Aleman cities, presented higher than average Cu and Pb concentrations, they did not exceeded the limits established by national environmental regulations, sediment quality guidelines, geoaccumulation index, and potential ecological risk indexes. Hence, the JAFS may be considered as not contaminated by Cu and Pb.

Simultaneous Droplet Generation with In-Series Droplet T-Junctions Induced by Gravity-Induced Flow.

Droplet microfluidics offers a wide range of applications, including high-throughput drug screening and single-cell DNA amplification. However, these platforms are often limited to single-input conditions that prevent them from analyzing multiple input parameters (e.g., combined cellular treatments) in a single experiment. Droplet multiplexing will result in higher overall throughput, lowering cost of fabrication, and cutting down the hands-on time in number of applications such as single-cell analysis. Additionally, while lab-on-a-chip fabrication costs have decreased in recent years, the syringe pumps required for generating droplets of uniform shape and size remain cost-prohibitive for researchers interested in utilizing droplet microfluidics. This work investigates the potential of simultaneously generating droplets from a series of three in-line T-junctions utilizing gravity-driven flow to produce consistent, well-defined droplets. Implementing reservoirs with equal heights produced inconsistent flow rates that increased as a function of the distance between the aqueous inlets and the oil inlet. Optimizing the three reservoir heights identified that taller reservoirs were needed for aqueous inlets closer to the oil inlet. Studying the relationship between the ratio of oil-to-water flow rates (Φ) found that increasing Φ resulted in smaller droplets and an enhanced droplet generation rate. An ANOVA was performed on droplet diameter to confirm no significant difference in droplet size from the three different aqueous inlets. The work described here offers an alternative approach to multiplexed droplet microfluidic devices allowing for the high-throughput interrogation of three sample conditions in a single device. It also has provided an alternative method to induce droplet formation that does not require multiple syringe pumps.

In vitro fertilizing capacity and chromatin condensation of deep frozen boar semen packaged in 0.5 and 5 ml straws.

The effect of the straw volume employed for semen freezing was studied in 14 ejaculates from seven boars, by evaluating the viability, IVF capacity and chromatin state of spermatozoa. Frozen-thawed semen from 0.5 and 5 ml straws was compared to fresh semen. The chromatin condensation degree was determined by flow cytometry, using propidium iodide as fluorochrome, and the chromatin stability was evaluated by inducing its decondensation with SDS and EDTA. The results obtained for IVF, motility and normal apical ridge (NAR) were: 91.64, 78.14 and 81.47% sperm penetration, 80.78, 68.38 and 70.83% monospermy, 10.86, 9.76 and 10.64% polyspermy, 87.14, 50.71 and 47.86% motility, 79.14, 56.14 and 53.36% NAR, for fresh semen, thawed semen in 0.5 and 5 ml straws, respectively. Frozen-thawed spermatozoa showed significantly increased (P < 0.05) chromatin compactness compared to fresh spermatozoa (55.42, 48.41 and 47.08 fluorescence units (MIFU), for fresh semen, thawed semen in 0.5 and 5 ml straws, respectively). Chromatin was significantly more unstable (P < 0.05) in spermatozoa frozen in 0.5 ml straws (174.7 MIFU) compared to those frozen in 5 ml straws (155.53 MIFU) or to those in fresh semen (149.74 MIFU).

Effects of post-thaw incubation on motility, acrosomal integrity and in vitro fertilizing capacity of boar spermatozoa cryopreserved in 0.5 and 5ml straws.

The effect of post-thaw incubation (0 vs. 5h at 15°C) and straw size (5 vs. 0.5ml) on motility, acrosomal integrity and in vitro fertilizing (IVF) capacity of cryopreserved boar spermatozoa was studied. In samples assessed immediately after thawing, no differences were found between the two straw sizes. After 5h post-thaw incubation, all parameters, except polyspermy, decreased and, spermatozoa packaged in 5ml straws showed better functional and IVF parameters than these in 0.5ml straws.

Análisis de la evolución de los recién nacidos menores de 2500 grs. en El Salvador / Analysis of the development of new born babies with less than 2.500 gr. at El Salvador Hospital

Introducción: se determinan características y riesgos a que estuvieron expuestos los niños que nacieron con peso inferior a 2.500 gramos entre el 30 de junio de 1988 y el 1 de julio de 1986 en el Hospital de El Salvador. Se comparan con niños que en el mismo período nacieron con 2.500 gramos o más. Método: análisis retrospectivo de las historias clínicas de ambos grupos. Análisis estadístico por comparación de los promedis (T de Student) y de las varianzas (F de Fischer), y cálculo de probabilidades. Resultados: cuatro niños del grupo de estudio (9%) y dos del grupo control (4,8%) fallecieron antes del año de vida. Los niños en estudio no presentaron más asfixia neonatal, su hospitalización neonatal fue más prolongada, tuvieron lactancia natural similar al grupo control, relacionándose ésta con la duración de su hospitalización neonatal. El grupo de estudio se enfermó más, se desnutrió más, recibió un número similar de controles de salud y en un 73% de los casos fue evaluado o tratado por su riesgo inherente a su peso de nacimiento. Los niños de peso inferior a 2.500 gramos al nacer tienen mayor riesgo de enfermarse y morir durante el primer año de vida