Exploring Optimization of Zeolites as Adsorbents for Rare Earth Elements in Continuous Flow by Machine Learning Techniques.

Unsupervised machine learning (ML) techniques are applied to the characterization of the adsorption of rare earth elements (REEs) by zeolites in continuous flow. The successful application of principal component analysis (PCA) and K-Means algorithms from ML allowed for a wide range assessment of the adsorption results. This global approach permits the evaluation of the different stages of the sorption cycles and their optimization and improvement. The results from ML are also used for the definition of a regression model to estimate other REEs' recoveries based on the known values of the tested REEs. Overall, it was possible to remove more than 70% of all REEs from aqueous solutions during the adsorption assays and to recover over 80% of the REEs entrapped on the zeolites using an optimized desorption cycle.

Crecimiento de cuyes (Cavia porcellus) con alimento para conejos y suplementación de vitamina C / Growth of Guinea pigs (Cavia porcellus) with feed for rabbits and supplementation of vitamin C

RESUMEN Objetivo. Evaluar el consumo, la digestibilidad y el crecimiento de cuyes alimentados con dos alimentos (A y K) formulados para esta especie y un alimento para conejos en crecimiento con suplementación de vitamina C (AC+VC). Materiales y métodos. Dieciocho cuyes (Cavia porcellus) de 248±38 g de peso vivo inicial se distribuyeron en un diseño completamente al azar con un arreglo factorial 3 × 2 (tipo de alimento y género). La ingesta de alimento, fibra detergente neutro, el aumento de peso, la conversión alimenticia, y los cambios en las variables morfométricas se midieron diariamente, mientras que la digestibilidad de la MS y FDN se determinaron al final del periodo. Resultados. No hubo diferencias en el consumo de MS (p=0.88); sin embargo, la digestibilidad de la MS fue mayor (p<0.01) en los alimentos para cuyes e inferior en AC+VC. El consumo y digestibilidad de FDN fueron mayores en AC+VC (p<0.01). La ganancia diaria fue similar entre los tratamientos (p>0.05). No hubo diferencias (p>0.01) en las variables morfométricas entre los alimentos, pero los machos fueron más grandes que las hembras (p<0.01). Conclusiones. Los cuyes pueden ser alimentados con alimento de conejo suplementado con vitamina C.

ABSTRACT Objective. An experiment was conducted to evaluate the feed intake, digestibility and growth of pigs fed with two feeds (A and K) specially formulated for this species and a commercial feed for growing rabbits with supplementation of vitamin C (RF+VC). Materials and methods. Eighteen Guinea pigs of 248±38 g initial body weight were distributed in a completely randomized design with factorial arrangement 3×2 (dietary treatments and sex). Feed and neutral detergent fiber intake, weight gain, feed/gain, and morphometric variables were measured individually for 30 days. Dry matter and neutral detergent fiber digestibility were measured during the last seven days of the experiment. Results. There were no differences on feed intake (p=0.88); however, the dry matter digestibility was higher (p<0.01) in feeds formulated for Guinea pigs (A and K) and lower in the rabbit feed plus vitamin C. The intake and digestibility of NDF were higher in the RF+VC and lower in feeds for Guinea pigs (p< 0.01). The average daily gain was similar among the treatments (p>0.05). There were no differences (p>0.01) in the morphometric variables among dietary treatments, but there were sex differences as the males were bigger than the females (p<0.01). Conclusions. The results indicate that Guinea pigs can be fed with rabbit feed supplemented with vitamin C.

A Review on Biological Processes for Pharmaceuticals Wastes Abatement-A Growing Threat to Modern Society.

Over the last decades, the production and consumption of pharmaceuticals and health care products grew manifold, allowing an increase in life expectancy and a better life quality for humans and animals, in general. However, the growth in pharmaceuticals production and consumption comes with an increase in waste production, which creates a number of challenges as well as opportunities for the waste management industries. The conventional current technologies used to treat effluents have shown to be inefficient to remove or just to reduce the concentrations of these types of pollutants to the legal limits. The present review provides a thorough state-of-the-art overview on the use of biological processes in the rehabilitation of ecosystems contaminated with the pharmaceutical compounds most commonly detected in the environment and eventually more studied by the scientific community. Among the different biological processes, special attention is given to biosorption and biodegradation.

Recovery of Rare Earth Elements from Wastewater Towards a Circular Economy.

The use of rare earth elements is a growing trend in diverse industrial activities, leading to the need for eco-friendly approaches to their efficient recovery and reuse. The aim of this work is the development of an environmentally friendly and competitive technology for the recovery of those elements from wastewater. Kinetic and equilibria batch assays were performed with zeolite, with and without bacterial biofilm, to entrap rare earth ions from aqueous solution. Continuous assays were also performed in column setups. Over 90% removal of lanthanum and cerium was achieved using zeolite as sorbent, with and without biofilm, decreasing to 70% and 80%, respectively, when suspended Bacillus cereus was used. Desorption from the zeolite reached over 60%, regardless of the tested conditions. When in continuous flow in columns, the removal yield was similar for all of the rare earth elements tested. Lanthanum and cerium were the elements most easily removed by all tested sorbents when tested in single- or multi-solute solutions, in batch and column assays. Rare earth removal from wastewater in open setups is possible, as well as their recovery by desorption processes, allowing a continuous mode of operation.

Análisis reproductivo en hembras de Iguana iguana criadas en cautiverio en Oaxaca, México / Reproductive analysis of Iguana iguana females raised in captivity in Oaxaca, Mexico

With the objective to evalúate the reproductive stage in green iguana (Iguana iguana) females maintained in captivity in Oaxaca, Mexico, a total of 137 females were used during six years. Iguanas were fed with concentrate, frijolillo plants (Desmodium infortum) and tulip flower (Tulipa gesneriana). The females were identified and housed in cages of 30 m² and were observed. Reproductive activities such as proestrus, estrus and pregnancy were daily recorded. In the stage of hatching, variables were measured in eggs that were incubated in styrofoam boxes with relative humidity of 65 to 85% and temperature between 28 to 34°C, and the newborn were measured after hatching. Results were analyzed with descriptive statistics and canonical correlation analysis using the Statistical Analysis System. At the beginning of the reproductive season the females weighed 975.9 ± 405 g and measured 27.9 ± 3.4 cm snout-vent length, with a relative clutch mass of 36.3 ± 7.1%, clutch size of 23.5 eggs, hatching success of 64.8%, and newborn weight of 12.5 ± 2.3 g. The periods of proestrus, estrus, and pregnancy were 85, 36.2 y 59.7 days, respectively. The females weight at the beginning of the reproductive stage, snout-vent length and total were correlated (canonical correlation r = 0.69, r = 0.64 and r = 0.64, respectively) with the number and weight of newborn, indicating the importance of female management before the breeding season.

Con el fin de evaluar la etapa reproductiva en hembras de iguana verde (Iguana iguana) mantenidas en cautiverio, en Oaxaca, México, se utilizaron 137 hembras, durante seis años. Se ofreció alimento concentrado, plantas de frijolillo (Desmodium infortum) y flor de tulipán (Tulipa gesneriana). Las hembras fueron identificadas y alojadas en jaulas de 30 m²; se observaron y registraron las actividades reproductivas de proestro, estro y gestación. En la etapa de eclosión, se midieron las variables de los huevos y se incubaron en cajas de unicel con humedad relativa de 65% a 85% y temperatura de 28° a 34°C; las crías se midieron después de la eclosión. Para el análisis de resultados se utilizó estadística descriptiva y análisis de correlación canónica con el paquete estadístico SAS. En el inicio del periodo reproductivo, las hembras pesaron 975.9 ± 405 g y midieron de longitud hocico-cloaca 27.9 ± 3.4 cm, la masa relativa de nidada fue de 36.3 ± 7.1%, con tamaño de 23.5 huevos, de los cuales eclosionaron 64.8%; las crías pesaron 12.5 ± 2.3 g. La duración de proestro, estro y gestación fue de 85, 36.2 y 59.7 días, respectivamente. El peso de las hembras al inicio de la etapa reproductiva, la longitud hocico-cloaca y el total se correlacionaron canónicamente (r = 0.69, r = 0.64 y r = 0.64) con el número y peso de las crías eclosionadas, lo que indica la importancia del manejo de las hembras antes del periodo reproductivo.