Leaching behaviour and the solution consumption of uranium-vanadium ore in alkali carbonate–bicarbonate column leaching

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Although heap leaching using sulfuric acid was introduced to the uranium industry in the 1950s, sodium carbonate–bicarbonate (alkaline) heap leaching of low-grade Ca-carbonate-rich uranium ores has recently gained popularity. This study presents the results of two column tests on a calcrete-type uranium–vanadium (carnotite) ore using a mixture of sodium carbonate and bicarbonate (Na2CO3/NaHCO3) as the leach solution. This data was kindly supplied by Toro Energy Ltd. The experimental data comprised physical–chemical leach information and two different irrigation rates (10 and 20 L/h·m2). The experimental data indicated that the carnotite ore with high calcium carbonate (CaCO3) can be leached effectively using the alkaline leach solution. The increase in the irrigation rate increased the uranium and vanadium extraction and decreased their concentration in the effluent. The column leach data was therefore fitted to a simplified first-order kinetic model using two approaches, a general form and a second based on the reagent consumption per unit mass of the initial valuable species (U and V). As reagent consumption is a key economic factor in the heap leaching process, having a kinetic leaching model incorporating reagent consumption would provide useful techno-economic information. In this regards a new leaching index of (β) is also introduced. Both approaches of the first order kinetic model provide a good agreement with the column testing data

Comedia sacramental : la noche dia / de Don Antonio Cordido y Montenegro

Precede al tít.: "Num. 134"Francisco Suriá y Burgada ejerce como impresor ca.: 1770-1805Sign.: A-B

Effects of Liposomes Contained in Thermosensitive Hydrogels as Biomaterials Useful in Neural Tissue Engineering

Indexación: Scopus.Advances in the generation of suitable thermosensitive hydrogels for the delivery of cells in neural tissue engineering demonstrate a delicate relationship between physical properties and capabilities to promote cell proliferation and differentiation. To improve the properties of these materials, it is possible to add liposomes for the controlled release of bioactive elements, which in turn can affect the physical and biological properties of the hydrogels. In the present investigation, different hydrogels based on Pluronic F127 have been formulated with the incorporation of chitosan and two types of liposomes of two different sizes. The rheological and thermal properties and their relation with the neurite proliferation and growth of the PC12 cell line were evaluated. Our results show that the incorporation of liposomes modifies the properties of the hydrogels dependent on the concentration of chitosan and the lipid type in the liposomes, which directly affect the capabilities of the hydrogels to promote the viability and differentiation of PC12 cells. © 2017 by the authors.http://www.mdpi.com/1996-1944/10/10/112

Determinación de la tasa de emisión de CO en cocinas mejoradas a leña con chimenea mediante el modelo de caja con ventilación constante

Con la finalidad de evaluar el impacto ambiental y en la saluddebido al uso de cocinas mejoradas a leña en general, se utilizan comoparámetros de evaluación las emisiones de CO generadas por la cocina [masacontaminante/tiempo] y las concentraciones intradomiciliarias [masacontaminante/volumen] medidas en el ambiente de cocinado generalmentepara periodos de 1 hora y/o 24 horas. Los procedimientos teórico-prácticosrealizados en éste trabajo permitieron determinar los valores de estosparámetros para un modelo de cocina mejorada a leña con chimenea de usocomún en Bolivia (Malena). Las pruebas experimentales se realizaron en elCentro de Pruebas de Cocinas ubicado en la ciudad de La Paz, a 3.600 ms.n.m. La metodología se basa en el uso de un modelo de caja asumiendo unatasa de ventilación constante en el ambiente de testeo. Los valores obtenidospermiten la comparación con estándares nacionales e internacionales. La tasade emisión resultante tiene un valor de 0,28 ± 0,1 [gCO/min] y 0,21 ± 0,08[gCO/min] para 1 hora y 24 horas respectivamente. La concentraciónpromedio de CO para 1 h fue de 5,21 ± 0,23 [mg/m3 CN], mientras que para24 h fue de 5,79 ± 0,44 [mg/m3 CN] bajo las condiciones de ventilaciónnatural del ambiente de testeo. En cuanto a la emisión, el nivel derendimiento respecto al estándar IWA/ISO 2012 permite establecer un Nivel4 donde la emisión debe ser < 0,42 [gCO/min], siendo este el nivel de mayoreficiencia de emisión. Por otro lado, respecto a las concentraciones, existe unadiferencia relativa de acuerdo a los límites de la OMS de 85% y de 87%respecto a la ley 1333 para 1h, mientras que para 24h la diferencia relativa es de 17% en relación a la OMS. Adicionalmente, la reducción relativa de lasconcentraciones respecto de una cocina tradicional para 1h es 97%

Spatial Mixing and Non-local Markov chains

We consider spin systems with nearest-neighbor interactions on an $n$-vertex $d$-dimensional cube of the integer lattice graph $\mathbb{Z}^d$. We study the effects that exponential decay with distance of spin correlations, specifically the strong spatial mixing condition (SSM), has on the rate of convergence to equilibrium distribution of non-local Markov chains. We prove that SSM implies $O(\log n)$ mixing of a block dynamics whose steps can be implemented efficiently. We then develop a methodology, consisting of several new comparison inequalities concerning various block dynamics, that allow us to extend this result to other non-local dynamics. As a first application of our method we prove that, if SSM holds, then the relaxation time (i.e., the inverse spectral gap) of general block dynamics is $O(r)$, where $r$ is the number of blocks. A second application of our technology concerns the Swendsen-Wang dynamics for the ferromagnetic Ising and Potts models. We show that SSM implies an $O(1)$ bound for the relaxation time. As a by-product of this implication we observe that the relaxation time of the Swendsen-Wang dynamics in square boxes of $\mathbb{Z}^2$ is $O(1)$ throughout the subcritical regime of the $q$-state Potts model, for all $q \ge 2$. We also prove that for monotone spin systems SSM implies that the mixing time of systematic scan dynamics is $O(\log n (\log \log n)^2)$. Systematic scan dynamics are widely employed in practice but have proved hard to analyze. Our proofs use a variety of techniques for the analysis of Markov chains including coupling, functional analysis and linear algebra

Biopesticide activity from drimanic compounds to control tomato pathogens

Indexación: Scopus.Tomato crops can be affected by several infectious diseases produced by bacteria, fungi, and oomycetes. Four phytopathogens are of special concern because of the major economic losses they generate worldwide in tomato production; Clavibacter michiganensis subsp. michiganensis and Pseudomonas syringae pv. tomato, causative agents behind two highly destructive diseases, bacterial canker and bacterial speck, respectively; fungus Fusarium oxysporum f. sp. lycopersici that causes Fusarium Wilt, which strongly affects tomato crops; and finally, Phytophthora spp., which affect both potato and tomato crops. Polygodial (1), drimenol (2), isonordrimenone (3), and nordrimenone (4) were studied against these four phytopathogenic microorganisms. Among them, compound 1, obtained from Drimys winteri Forst, and synthetic compound 4 are shown here to have potent activity. Most promisingly, the results showed that compounds 1 and 4 affect Clavibacter michiganensis growth at minimal inhibitory concentrations (MIC) values of 16 and 32 μg/mL, respectively, and high antimycotic activity against Fusarium oxysporum and Phytophthora spp. with MIC of 64 μg/mL. The results of the present study suggest novel treatment alternatives with drimane compounds against bacterial and fungal plant pathogens. © 2018 by the authors.https://www.mdpi.com/1420-3049/23/8/205

Sequence Decoding of 1D to 2D Self-Assembling Cyclic Peptides

This is the peer reviewed version of the following article: S. Díaz, I. Insua, G. Bhak, J. Montenegro, Chem. Eur. J. 2020, 26, 14765, which has been published in final form at https://doi.org/10.1002/chem.202003265. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.The inherent ability of peptides to self-assemble with directional and rationally predictable interactions has fostered a plethora of synthetic two-dimensional (2D) supramolecular biomaterials. However, the design of peptides with hierarchical assembly in different dimensions across mesoscopic lengths remains a challenging task. We here describe the structural exploration of a d/l-alternating cyclic octapeptide capable of assembling one-dimensional (1D) nanotubes in water, which subsequently pack laterally to form giant 2D nanosheets up to 500 μm long with a constant 3.2 nm thickness. Specific amino acid mutations allowed the mapping of structure–assembly relationships that determine 2D self-assembly. Nine peptide modifications were studied, revealing key features in the peptide sequence that nanosheets tolerated, while a total of three peptide variants included modifications that compromised their 2D arrangement. These lessons will serve as guide and inspiration for new 2D supramolecular peptide designsThis work was partially supported by the Spanish Agencia Estatal de Investigación (AEI) [SAF2017-89890-R], Xunta de Galicia (AD031 2016, ED431C 2017/25 and ED431G2019/03) and the European Commission (EC) (European Regional Development Fund-ERDF) Instituto de Salud Carlos III (COV20/00297). I.I. thanks the European Commission (EC) and AEI for MSCA-IF (2018-843332) and Juan de la Cierva (FJCI-2017-31795) fellowships, respectively. J.M. thanks the Ramón y Cajal (RYC-2013-13784), ERC- STG (DYNAP, 2016-677786), ERC-POC (TraffikGene, 2019-838002) and Human Frontier Science Programme Young Investigator Grant (RGY0066/2017) for fundingS

Hemi-Synthesis and Anti-Oomycete Activity of Analogues of Isocordoin

Indexación: Web of Science; Scopus.An efficient synthesis of a series of 4-oxyalkyl-isocordoin analogues (2–8) is reported for the first time. Their structures were confirmed by1H-NMR,13C-NMR, and HRMS. Their anti-oomycete activity was evaluated by mycelium and spores inhibition assay against two selected pathogenic oomycetes strains: Saprolegnia parasitica and Saprolegnia australis. The entire series of isocordoin derivatives (except compound 7) showed high inhibitory activity against these oomycete strains. Among them, compound 2 exhibited strong activity, with minimum inhibitory concentration (MIC) and minimum oomyceticidal concentration (MOC) values of 50 µg/mL and 75 µg/mL, respectively. The results showed that 4-oxyalkylated analogues of isocordoin could be potential anti-oomycete agents.http://www.mdpi.com/1420-3049/22/6/96

Non-linear Dependence of L(B) on L(FIR) and M(H2) among Spiral Galaxies and Effects of Tidal Interaction

Through the study of a carefully selected sample of isolated spiral galaxies, we have established that two important global physical quantities for tracing star forming activities, L(FIR) and M(H2), have non-linear dependence on another commonly cited global quantity L(B). Furthermore we show that simple power law relations can effectively describe these non-linear relations for spiral galaxies spanning four orders of magnitude in FIR and M(H2) and nearly three orders of magnitude in L(B). While the existence of non-linear dependence of M(H2) (assuming a constant CO-to-H2 conversion) and L(FIR) on optical luminosity L(B) has been previously noted in the literature, an improper normalization of simple scaling by L(B) has been commonly used in many previous studies to claim enhanced molecular gas content and induced activities among tidally interacting and other types of galaxies. We remove these non-linear effects using the template relations derived from the isolated galaxy sample and conclude that strongly interacting galaxies do not have enhanced molecular gas content, contrary to previous claims. With these non-linear relations among L(B), L(FIR) and M(H2) properly taken into account, we confirm again that the FIR emission and the star formation efficiency L(FIR)/M(H2) are indeed enhanced by tidal interactions. Virgo galaxies show the same level of M(H2) and L(FIR) as isolated galaxies. We do not find any evidence for enhanced star forming activity among barred galaxies.Comment: 19 pages and 5 figures, requires AAS style files, ApJ, accepte