Phosphate sorption and desorption by two contrasting volcanic soils of equatorial Africa

Volcanic soils cover 1% of the Earth's surface but support 10% of the world's population. They are among the most fertile soils in the world, due to their excellent physical properties and richness in available nutrients. The major limiting factor for plant growth in volcanic soils is phosphate fixation, which is mainly attributable to active species of aluminium and iron. The sorption and desorption of phosphate is studied on the surface horizons of two African agricultural soils, a silandic Andosol (Rwanda) and a vitric Andosol (São Tomé and Principe). Both soils are slightly acid. The silandic Andosol is rich in active aluminium forms, while the vitric Andosol has high amounts of crystalline iron and aluminium oxides. Sorption isotherms were determined by equilibrating at 293K soil samples with phosphate solutions of concentrations between 0 and 100 mg P L-1 in NaNO3; phosphate was determined by visible spectrophotometry in the equilibrium solution. To study desorption, the soil samples from the sorption experiment were equilibrated with 0.02 M NaNO3. The isotherms were adjusted to mathematical models. In almost all the concentration range, the adsorption of phosphate by the silandic Andosol was greater than 90% of the amount added, being lower in the vitric Andosol but always higher than 65%. The high sorption by the silandic Andosol is attributed to its richness in non-crystalline Fe and Al, while in the vitric Andosol crystalline iron species seem to play a relevant role in the adsorption. The sorption isotherms of both soils fitted to the Temkin model, the adjustment to the Langmuir or Freundlich models being unsatisfactory; throughout the range studied, the sorption increases with increasing phosphorus concentration, a maximum sorption is not predictable (as occurs when the sorption is adjusted to the Langmuir model). For an added P concentration of 100 mg L-1 (3.2 mmol L-1), the sorption is 47.7 mmol P g-1 in the silandic Andosol and 41.6 mmol P g-1 in the vitric Andosol. The desorption is low and the comparison of the sorption and desorption isotherms reveals a pronounced hysteresis, that is, the irreversibility of the sorption. The high phosphate sorption and its irreversibility are comparable to those published for other volcanic soils with high contents of allophane, active aluminium and free iron. The strong phosphate adsorption is a serious limiting factor for plant growth, which requires a careful management of phosphorus fertilization.S

Sorption and Desorption of Vanadate, Arsenate and Chromate by Two Volcanic Soils of Equatorial Africa

Sorption of oxyanions by soils and mineral surfaces is of interest due to their role as nutrients or pollutants. Volcanic soils are variable charge soils, rich in active forms of aluminum and iron, and capable of sorbing anions. Sorption and desorption of vanadate, arsenate, and chromate by two African andosols was studied in laboratory experiments. Sorption isotherms were determined by equilibrating at 293 K soil samples with oxyanion solutions of concentrations between 0 and 100 mg L−1 V, As, or Cr, equivalent to 0−2.0 mmol V L−1, 0−1.3 mmol As L−1, and 0−1.9 mmol Cr L−1, in NaNO3; V, As, or Cr were determined by ICP-mass spectrometry in the equilibrium solution. After sorption, the soil samples were equilibrated with 0.02 M NaNO3 to study desorption. The isotherms were adjusted to mathematical models. After desorption with NaNO3, desorption experiments were carried out with a 1 mM phosphate. The sorption of vanadate and arsenate was greater than 90% of the amount added, while the chromate sorption was much lower (19–97%). The sorption by the Silandic Andosol is attributed to non-crystalline Fe and Al, while in the Vitric Andosol, crystalline iron species play a relevant role. The V and Cr sorption isotherms fitted to the Freundlich model, while the As sorption isotherms conformed to the Temkin model. For the highest concentrations of oxyanions in the equilibrating solution, the sorbed concentrations were 37–38 mmol V kg−1, 25 mmol As kg−1, and 7.2–8.8 mmol Cr kg−1. The desorption was low for V and As and high for Cr. The comparison of the sorption and desorption isotherms reveals a pronounced hysteresis for V in both andosols and for Cr in the Silandic Andosol. Phosphate induced almost no V desorption, moderate As desorption, and considerable Cr desorptionS

Aprendizaje léxico de una lengua extranjera mediante una metodología basada en la adquisición de contenidos

Este trabajo se propone refl exionar sobre una serie de aspectos relacionados con las últimas investigaciones centradas en el aprendizaje léxico en una lengua extranjera y analizar cómo todos estos aspectos pueden ser integrados mediante la aplicación de la metodología basada en contenidos con la fi nalidad de incrementar el repertorio léxico de los alumnos de forma natural, signifi cativa y duradera. The aim of this paper is to refocus attention on some aspects connected to the latest research on lexical learning in a foreign language and to analyze how all those basic and fundamental aspects can be integrated by using Content-based Instruction in order to improve our students’ lexicon in a natural, meaningful way

Novel Findings about Double-Loaded Curcumin-in-HPβcyclodextrin-in Liposomes: Effects on the Lipid Bilayer and Drug Release

In this study, the encapsulation of curcumin (Cur) in “drug-in-cyclodextrin-in-liposomes (DCL)” by following the double-loading technique (DL) was proposed, giving rise to DCL–DL. The aim was to analyze the effect of cyclodextrin (CD) on the physicochemical, stability, and drug-release properties of liposomes. After selecting didodecyldimethylammonium bromide (DDAB) as the cationic lipid, DCL–DL was formulated by adding 2-hydroxypropyl-α/β/γ-CD (HPβCD)–Cur complexes into the aqueous phase. A competitive effect of cholesterol (Cho) for the CD cavity was found, so cholesteryl hemisuccinate (Chems) was used. The optimal composition of the DCL–DL bilayer was obtained by applying Taguchi methodology and regression analysis. Vesicles showed a lower drug encapsulation efficiency compared to conventional liposomes (CL) and CL containing HPβCD in the aqueous phase. However, the presence of HPβCD significantly increased vesicle deformability and Cur antioxidant activity over time. In addition, drug release profiles showed a sustained release after an initial burst effect, fitting to the Korsmeyer-Peppas kinetic model. Moreover, a direct correlation between the area under the curve (AUC) of dissolution profiles and flexibility of liposomes was obtained. It can be concluded that these “drug-in-cyclodextrin-in-deformable” liposomes in the presence of HPβCD may be a promising carrier for increasing the entrapment efficiency and stability of Cur without compromising the integrity of the liposome bilayer

Mexican Women’s Parliament: Is it the way to reach gender equity

One of the most important decisions taken by the Mexican Assembly is to approve the annual budget of the country. Beijing Agreements in 1995 change the perception in the parliament which was merely for men. So, the few Mexican women in the parliament from the different parties organized the “Women’s Parliament” to reach gender equity not only in the different parties but in political, economic and social life. This year the women deputies and senators divided the country in five regions and had meetings outside of the central parliament office. at San Lázaro in Mexico City. These meetings tried to include the rich diversity demands from the different states, municipals and NGOs that participate during three weeks between February and March 2005. At the end of the regional meetings all the agreements were approved in the federal parliament. After Beijing Agreements + 10 not only the government but politicians are aware of improving empowerment women which has been a goal in a “machista” and traditional societ

Fucoxanthin-Containing Cream Prevents Epidermal Hyperplasia and UVB-Induced Skin Erythema in Mice

Microalgae represent a source of bio-active compounds such as carotenoids with potent anti-inflammatory and antioxidant properties. We aimed to investigate the effects of fucoxanthin (FX) in both in vitro and in vivo skin models. Firstly, its anti-inflammatory activity was evaluated in LPS-stimulated THP-1 macrophages and TNF-α-stimulated HaCaT keratinocytes, and its antioxidant activity in UVB-irradiated HaCaT cells. Next, in vitro and ex vivo permeation studies were developed to determine the most suitable formulation for in vivo FX topical application. Then, we evaluated the effects of a FX-containing cream on TPA-induced epidermal hyperplasia in mice, as well as on UVB-induced acute erythema in hairless mice. Our results confirmed the in vitro reduction of TNF-α, IL-6, ROS and LDH production. Since the permeation results showed that cream was the most favourable vehicle, FX-cream was elaborated. This formulation effectively ameliorated TPA-induced hyperplasia, by reducing skin edema, epidermal thickness, MPO activity and COX-2 expression. Moreover, FX-cream reduced UVB-induced erythema through down-regulation of COX-2 and iNOS as well as up-regulation of HO-1 protein via Nrf-2 pathway. In conclusion, FX, administered in a topical formulation, could be a novel natural adjuvant for preventing exacerbations associated with skin inflammatory pathologies as well as protecting skin against UV radiation

Análisis del grado de degradación en diferentes agregados pétreos utilizados como materiales granulares de estructuras de pavimento en Bogotá

Trabajo de investigaciónSe analizó propiedades mecánicas como tenacidad y desgaste de materiales seleccionado en dos (2) canteras, ubicadas en la sabana de Bogotá y una (1) localizadas en el municipio de Chaparral, departamento del Tolima, mediante el ensayo de “DEGRADACIÓN DE LOS AGREGADOS PÉTREOS A CAUSA DE LA COMPACTACIÓN POR IMPACTOS, INV E – 243 – 13” y el ensayo “RESISTENCIA AL DESGASTE DE LOS AGREGADOS DE TAMAÑOS MENORES DE 37.5MM (1½”) POR MEDIO DE LA MÁQUINA DE LOS ÁNGELES INV E – 218 – 13” que se encuentra en el Manual de Normas de Ensayos de Materiales para Carretera del INVIAS en su versión 2013.INTRODUCCIÓN 1 GENERALIDADES DEL TRABAJO DE GRADO 2 MARCOS DE REFERENCIA 3 METODOLOGÍA 4 ANÁLISIS DE RESULTADOS 5 CONCLUSIONES Y RECOMENDACIONES 6 BIBLIOGRAFÍA ANEXOSEspecializaciónEspecialista en Ingeniería de Pavimento

Application of adipose-derived mesenchymal stem cells in an in vivo model of peripheral nerve damage

[EN] Background: Neuropathic pain is one of the most difficult to treat chronic pain syndromes. It has significant effects on patients’ quality of life and substantially adds to the burden of direct and indirect medical costs. There is a critical need to improve therapies for peripheral nerve regeneration. The aim of this study is to address this issue by performing a detailed analysis of the therapeutic benefits of two treatment options: adipose tissue derived-mesenchymal stem cells (ASCs) and ASC-conditioned medium (CM). Methods: To this end, we used an in vivo rat sciatic nerve damage model to investigate the molecular mechanisms involved in the myelinating capacity of ASCs and CM. Furthermore, effect of TNF and CM on Schwann cells (SCs) was evaluated. For our in vivo model, biomaterial surgical implants containing TNF were used to induce peripheral neuropathy in rats. Damaged nerves were also treated with either ASCs or CM and molecular methods were used to collect evidence of nerve regeneration. Post-operatively, rats were subjected to walking track analysis and their sciatic functional index was evaluated. Morphological data was gathered through transmission electron microscopy (TEM) of sciatic nerves harvested from the experimental rats. We also evaluated the effect of TNF on Schwann cells (SCs) in vitro. Genes and their correspondent proteins associated with nerve regeneration were analyzed by qPCR, western blot, and confocal microscopy. Results: Our data suggests that both ASCs and CM are potentially beneficial treatments for promoting myelination and axonal regeneration. After TNF-induced nerve damage we observed an upregulation of c-Jun along with a downregulation of Krox-20 myelin-associated transcription factor. However, when CM was added to TNF-treated nerves the opposite effect occurred and also resulted in increased expression of myelin-related genes and their corresponding proteins. Conclusion: Findings from our in vivo model showed that both ASCs and CM aided the regeneration of axonal myelin sheaths and the remodeling of peripheral nerve morphologySIThis study was supported by the Fundación Leonesa ProNeurociencias. The AW’s Lab was supported by AEI/FEDER, EU (RTI2018-097503-B-I00) and the European Community’s H2020 Framework Program ERC Consolidator Grant (865157- MYERIBO

El efecto del feedback y de la instrucción explícita de las convenciones del discurso académico sobre la producción escrita en inglés de estudiantes universitarios

Memoria ID-0025. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2014-2015