Direct electrochemical detection mechanism of ammonia in aqueous solution using Cu-decorated Si microelectrodes

Most of the reports on electrochemical ammonia detection with copper electrodes have been performed at pH 10 or higher. However, according to phase diagrams, no reactions take place between copper and ammonia under those conditions, qualifying such detec­tion of ammonia as indirect. This short paper deals with the detection of ammonia concen­tration in the micromolar range through a direct mechanism at pH 9, using a Cu-decorated microstructured Si electrode. The reaction mechanism is thoroughly studied

The Importance of Liming with an Appropriate Liming Material: Long-Term Experience with a Typic Palexerult

[EN] Aluminium phytotoxicity is considered the main limiting factor for crop productivity in agricultural acid soils. Liming is a common practice used to improve acidic soil properties, but an appropriate liming material is essential for both agricultural productivity and environmental sustainability. A long-term field experiment with two liming amendments (dolomitic limestone and limestone) was developed during 10 years to determine the changes in soil acidity and assess the effects on crop (rye) yields. Although the adverse effects of the soil acidity conditions were alleviated with both amendments tested, dolomitic limestone was the most effective in the short- and long-term period. In terms of the saturation of exchange complex, dolomitic limestone had a better efficiency, likely based on its rate of dissolution. No significant changes in soil organic matter and exchangeable potassium levels between the treatments tested were found. Both liming materials significantly increased the rye total biomass, but interestingly, significant correlations were showed between tissue levels of magnesium and biomass production, but not between the latter and calcium. The increases in rye biomass production compared with control soils at the end of the research were the following: dolomitic limestone, 47%, and limestone, 32%. A link between an increase in magnesium bioavailability and biomass production was found, as well as between magnesium rye content and total, spike and stem biomass. Hence, it could conceivably be hypothesized that since magnesium is crucial for the transport of assimilates from source leaves to sink organs, alleviating its deficiency leads to avoiding the reducing growth rate of sink organs. Although further investigations are needed to gain a better understanding of liming on the biological, chemical and physical soil properties in the long term, our research provides support for the conceptual premise that an appropriate selection of liming material is crucial for the productivity of acid soils.S

Planktonic eukaryote molecular diversity: discrimination of minerotrophic and ombrotrophic peatland pools in Tierra del Fuego (Argentina)

We investigated the composition of the smallest size fraction (<3 µm) of eukaryotic plankton communities of five pools located in the Rancho Hambre peat bog in Argentinean Tierra del Fuego with an IlluminaHiSeq massive sequencing approach applied to the v9 region of the eukaryotic SSU rRNA gene. Communities were generally dominated by chrysophytes, with a good representation of Perkinsea and Cercozoa clade NC-10. A community composition analysis performed using GUniFraC separated minerotrophic and ombrotrophic sites, reflecting perfectly the classification of the sites based on environmental data. However, this separation disappeared when more weight was given to abundant phylotypes, suggesting that subordinate phylotypes were responsible for site discrimination. The 5% best indicators for, respectively, minerotrophic and ombrotrophic environments were searched using an IndVal analysis. Among these, autotrophic taxa were more common in minerotrophic environments, whereas mixotrophic taxa represented best ombrotrophic water bodies. However, the ecological traits of many taxa have still not been determined, and still needs to be investigated for a better understanding of freshwater systems ecolog

Estudio de factibilidad para la creación de una empresa de formación musical docente

108 Páginas.​GScholar es un emprendimiento de tres personas, estudiantes de la especialización en Gerencia Educativa de la Universidad de la Sabana, quienes unen esfuerzos desde cada una de sus especialidades y preferencias para ofrecer a las instituciones educativas de educación inicial, media y media vocacional diferentes propuestas de formación artística a sus docentes. GScholar nace con el fin de satisfacer una necesidad del mundo escolar, ya que actualmente las universidades e instituciones de formación para el desarrollo humano y el trabajo no ofrecen el tipo de formación que GScholar pretende brindar, ya que los cursos teórico prácticos de corta duración no son ofrecidos por estas entidades

Long-Term Effects of Calcium-Based Liming Materials on Soil Fertility Sustainability and Rye Production as Soil Quality Indicators on a Typic Palexerult

[EN] Liming is a common practice used to improve acidic soil properties, as is essential for agricultural quality. A long-term field experiment with one lime rate (6000 kg/ha of carbonate calcium equivalent) and three calcium-based liming amendments (gypsum, limestone and sugar foam) was maintained on a Typic Palexerult for 10 years in order to determine changes in soil acidity and to assess the effects on crop (rye) yields. The soil acidity conditions decreased with all the amendments tested, but the sugar foam and limestone was more effective than gypsum over a long-term period. No significant changes in organic soil matter levels between the treatments tested were found. Interestingly, an increase in the leaching of organic soil matter was observed in limed soils. Lime application significantly increased the total rye biomass compared to the control soils during the whole experiment (2002–2011). Yield trends observed in spike and stem biomass were similar to those reported for total rye biomass. In this respect, at the end of the research, gypsum, limestone and sugar foam increased in relation to the total production of rye biomass by 16%, 32% and 38%, respectively, as compared to the control soils. Additionally, a significant and prolonged difference in calcium concentrations in rye stems between unlimed and limed subplots was observed. However, in spite of the results presented here, further investigations are needed to gain a better understanding of the long-term effects of liming on the chemical properties of soil.S

Effects of Leonardite Amendments on Vineyard Calcareous Soil Fertility, Vine Nutrition and Grape Quality

[EN] Vineyard calcareous soils are usually low in organic matter, which makes them prone to physical, chemical, and biological degradation. Besides, these soils are also usually poor in various nutrients in plant-available form, e.g., iron. To make up for this lack of soil fertility, on the one hand, manures, and on the other, iron chelates are usually used. However, the soil application of these materials is not free from problems, and other amendments based on leonardites could be advantageously used as an alternative. Therefore, two organic amendments, one leonardite alone (1 Mg/ha), and the other leonardite (1 Mg/ha) plus ferrous sulphate heptahydrate (0.5 Mg/ha), were tested for three years in a commercial vineyard calcareous plot under Mediterranean climate. The effects of these amendments on soil fertility, plant nutrient contents, and berry quality were studied against a control of bare soil by means of a fully randomized trial with three repetitions per treatment. Soil organic matter (SOM) increased as a consequence of both leonardite treatments, but much more than expected on the basis of a simple mass transfer from the amendments. With the ferrous-sulphate-heptahydrate-supplemented leonardite, the increase in SOM was noticeably higher. This is explained on the basis of nutrient quantity and intensity-pH-related effects, which increased soil nutrient plant-availability and presumably enhanced vine root growth. In response to the higher plant availability of nutrients, the petiole nutrient concentrations were observed to increase under the leonardite treatments. However, only a trend to increase potassium in petioles and in grape must, linked to a decrease of grape must pH, was observed in harvest quality under the leonardite treatments. Leonardite and adequately supplemented leonardite seem to have potential for increasing SOM contents and nutrient plant-availability, thus improving the soil fertility of vineyard calcareous soils.SIThe authors are grateful to Bodegas Vega Sicilia, S.A. for providing the vineyard for the experimental plots

Morphological Analysis of Bronchial Arteries and Variants with Computed Tomography Angiography

The aim of our study was to determine the prevalence of anatomical variants of bronchial arteries using computed tomographic angiography in a population of northeastern Mexico. An observational, transversal, descriptive, comparative, retrospective study was performed using 139 imaging studies of Mexican patients in which we evaluated the following parameters from the left and right bronchial arteries: artery origin, branching pattern, arterial ostium, vertebral level of origin, diameter, and mediastinal trajectory. The anatomies of the bronchial arteries were similar in both genders, except distribution for vertebral origin level

Viticultural and Biotechnological Strategies to Reduce Alcohol Content in Red Wines

Viticultural and biotechnological strategies are two approaches to deal with higher must sugar levels at harvest time. A wide range of factors could significantly affect sugar accumulation in the grape such as choice of vineyard site, soil composition, irrigation strategy, rootstock, and grape cultivar selection as well as grape yield. In this sense, approaches to canopy management are continually evolving in response to changes in other vineyard management practices; some of these could contribute to reduce soluble sugars on grape berries at harvest time. On the other hand, among possible biotechnological strategies, one of the most relevant is the control of the fermentative process by using selected yeast strains. In this chapter, we will show how some viticultural practices have influenced the accumulation of soluble sugars and other enological parameters in grape berries at harvest time. We will also report how a careful yeast selection and the implementation of different fermentation strategies can also contribute to reduce ethanol content in wines

Hypoparathyroidism: Basis for the approach and appropiate treatment

RESUMEN: El hipoparatiroidismo es definido como hipocalcemia en presencia de hormona paratiroidea baja (< 20 pg/mL) o indetectable. Es una enfermedad rara con una prevalencia estimada de 37 casos por 100.000 habitantes. Aunque la etiología es variada, la causa más frecuente, en 75 % de los casos, es el hipoparatiroidismo posoperatorio. Esta situación puede ocurrir en cualquier cirugía de cuello, pero es más frecuente en la resección de tiroides. Otras causas infrecuentes incluyen trastornos autoinmunes como el síndrome poliglandular tipo 1, desórdenes genéticos como la anomalía de DiGeorge o trastornos funcionales como la hipomagnesemia. Los síntomas agudos más importantes de la hipocalcemia son la irritación neuromuscular, como parestesias y convulsiones. Crónicamente se pueden presentar calcificaciones en varios sitios del cuerpo incluyendo los ganglios basales. El diagnóstico y enfoque de esta enfermedad parte de un valor disminuido de calcio combinado con PTH menor de 20 pg/mL, siempre excluyéndose hipomagnesemia. Además, debe solicitarse fósforo y calciuria de 24 horas. El tratamiento se realiza con reposición oral de calcio y vitamina D activa (calcitriol). En algunos casos con hipercalciuria se pueden usar diuréticos tipo tiazida. Recientemente se aprobó en Estados Unidos y Europa, el uso de hormona recombinante paratiroidea 1-84 en pacientes con hipoparatiroidismo que no estén controlados fácilmente con calcio y calcitriol o en aquellos que tengan complicaciones o deterioro en la calidad de vida. Palabras clave: Calcio; Fósforo; Hipocalcemia; Hipoparatiroidismo; Paratiroides.ABSTRACT: Hypoparathyroidism is an infrequent disorder. The main characteristic is low calcium with low PTH. The estimate prevalence is 37 cases per 100.000 inhabitants. The most frequent cause (75 % of all cases) is removal of parathyroid gland during neck surgery. Other causes are polyglandular autoimmune syndrome type 1, genetic disorders such as DiGeorge anomaly, or functional disorders like hypomagnesemia. Hypocalcemia may produce neuromuscular symptoms and seizures. Chronic manifestations include ectopic calcifications. The diagnosis of hypoparathyroidism is made when calcium is below normal in presence of low or undetectable PTH (< 20 pg/mL). Magnesium, phosphorus and 24-hour urine calcium should be measured in all patients with hypoparathyroidism. The management of this disease is with calcium supplements plus active vitamin D (calcitriol). In some cases, with hypercalciuria, a thiazide diuretic may be used. Recently, the use of recombinant PTH 1-84 was approved in the United Stated and Europe. This treatment is indicated in patients with uncontrolled hypoparathyroidism despite increasing doses of calcium and calcitriol or in patients with complications of hypoparathyroidism or deceased quality of life. Key words: Calcium; Hypocalcemia; Hypoparathyroidism; Parathyroid; Phosphorus