Electrochemical reduction of CO2 to formate on nanoparticulated Bi-Sn-Sb electrodes

Human activities during the last century have increased the concentration of greenhouse gases in Earth's atmosphere, mainly carbon dioxide (CO2), and the impacts of climate change around the world are becoming more damaging. Therefore, scientific research is needed to mitigate the consequences of atmospheric CO2, and, among others, the electrochemical CO2 conversion to useful chemicals is one of the most interesting alternatives. Herein, different Bi, Sn and Sb systems were synthesised as nanoparticles, supported on carbon (Vulcan XC-72R) and finally used to manufacture electrodes. The Bi-Sn-Sb nanoparticulated systems and their corresponding electrodes were characterised by TEM, XPS, ICP-OES and SEM. Electrochemical reduction of CO2 to formate was performed in an electrochemical H-type cell in a CO2-saturated KHCO3 and KCl solution. The Bi-Sn-Sb electrodes exhibited good activity and selectivity for the CO2 reduction towards formate. Particularly, Bi95Sb05/C and Bi80Sn10Sb10/C electrodes showed improved stability compared to previous works, keeping values of formate efficiency over 50 % after 24 h.This research was funded by the MICINN Spanish Ministry, through the projects CTQ2016-76231-C2-2-R (AEI/FEDER, UE) and PID2019-108136RB-C32

A MAXWELL THEORY FOR THE SCATTERING OF TM POLARIZED

We present a rigorous theory for oblique incident Hermite-Gaussian beams, diffracted by two slits of width and separation d, in a thick metallic screen for the case of polarization TM(S). The far field spectra as a function of several opto-geometrical parameters, wavelength λ, slit width , separation d, incidence angle θ i and Hermite order m is analyzed. In the vectorial diffraction region given when λ/ >0.2, where is the incident wavelength and as a function of the separation between slits d; we have numerically analyzed: the far field spectra, the energy diffracted along the incident beam direction (E i ), and the validity of an approximate diffraction (scalar) property, namely E i = Nτ/λ.Se presenta una teoría vectorial de la difracción de haces Hermite–Gauss sobre una pantalla metálica de espesor h con dos rendijas de ancho l y separación d. los haces inciden oblicuamente con polarización TM. Estudiamos numéricamente los patrones de difracción en campo lejano como función de los parámetros opto–geométricos: longitud de onda λ, ancho de rendija l, separación d, ángulo de incidencia θ i y orden del polinomio de Hermite m. Por otra parte, en la región vectorial de la difracción dada por λ⁄l > 0.2 donde λ es la longitud de onda incidente, se analiza numéricamente la energía difractada a lo largo de la dirección del haz incidente (E i ) y la validez de la propiedad de la difracción escalar E i = Nτ/λ donde τ es el coeficiente de transmisión y N el número de rendijas.Conacy

Efectos de presentar comida libre y un programa de reforzamiento continuo sobre las presiones a una palanca por comida en ratas

Six food-deprived rats were each exposed to a procedure in which lever pressing produced food in the presence and absence of free food. Although the highest frequency of lever pressing was observed when each lever press was reinforced with food in the absence of any supplementary free food, all six rats continued to press the lever when free food was available. The rats consumed approximately the same amount of food when free food was available, whether or not lever pressing was also reinforced. When each lever press was reinforced in the presence of free food, approaches to the free-food cup (and free-food consumption) decreased from the beginning to the end of the session, whereas lever pressing increased gradually across the session. These intra-session changes in behavior were interpreted in terms of the satiation of consummatory behavior.Se expuso a seis ratas privadas de comida a un procedimiento en el cual las presiones a una palanca resultaron en la entrega de una bolita de comida en la presencia o ausencia de comida disponible. Aún cuando se observó la frecuencia más alta de presiones a la palanca durante la condición en la cual se reforzó cada presión en la ausencia de comida disponible, las seis ratas continuaron presionando la palanca cuando había comida disponible. Cuando se reforzaron las presiones a la palanca o éstas ocurrieron sin consecuencia alguna, las ratas consumieron aproximadamente la misma cantidad de comida cuando ésta estuvo disponible.Cuando se reforzó cada presión a la palanca en la presencia de la comida libre, las aproximaciones a la charola (y el consumo de esta comida) disminuyeron del principio al final de la sesión, mientras que las presiones a la palanca aumentaron gradualmente conforme transcurrió la sesión. Los cambios intra sesión de la conducta se interpretaron en términos de la saciedad de la conducta consumatoria

Manganese Inhalation as a Parkinson Disease Model

The present study examines the effects of divalent and trivalent Manganese (Mn2+/Mn3+) mixture inhalation on mice to obtain a novel animal model of Parkinson disease (PD) inducing bilateral and progressive dopaminergic cell death, correlate those alterations with motor disturbances, and determine whether L-DOPA treatment improves the behavior, to ensure that the alterations are of dopaminergic origin. CD-1 male mice inhaled a mixture of Manganese chloride and Manganese acetate, one hour twice a week for five months. Before Mn exposure, animals were trained to perform motor function tests and were evaluated each week after the exposure. By the end of Mn exposure, 10 mice were orally treated with 7.5 mg/kg L-DOPA. After 5 months of Mn mixture inhalation, striatal dopamine content decreased 71%, the SNc showed important reduction in the number of TH-immunopositive neurons, mice developed akinesia, postural instability, and action tremor; these motor alterations were reverted with L-DOPA treatment. Our data provide evidence that Mn2+/Mn3+ mixture inhalation produces similar morphological, neurochemical, and behavioral alterations to those observed in PD providing a useful experimental model for the study of this neurodegenerative disease

Revealing the Intrinsic Restructuring of Bi2O3 Nanoparticles into Bi Nanosheets during Electrochemical CO2 Reduction

Bismuth is a catalyst material that selectively produces formate during the electrochemical reduction of CO2. While different synthesis strategies have been employed to create electrocatalysts with better performance, the restructuring of bismuth precatalysts during the reaction has also been previously reported. The mechanism behind the change has, however, remained unclear. Here, we show that Bi2O3 nanoparticles supported on Vulcan carbon intrinsically transform into stellated nanosheet aggregates upon exposure to an electrolyte. Liquid cell transmission electron microscopy observations first revealed the gradual restructuring of the nanoparticles into nanosheets in the presence of 0.1 M KHCO3 without an applied potential. Our experiments also associated the restructuring with solubility of bismuth in the electrolyte. While the consequent agglomerates were stable under moderate negative potentials (−0.3 VRHE), they dissolved over time at larger negative potentials (−0.4 and −0.5 VRHE). Operando Raman spectra collected during the reaction showed that under an applied potential, the oxide particles reduced to metallic bismuth, thereby confirming the metal as the working phase for producing formate. These results inform us about the working morphology of these electrocatalysts and their formation and degradation mechanisms.B.Á.-B. is grateful to the MICINN Spanish Ministry for the predoctoral grant (reference CTQ2016-76231-C2-2-R). B.Á.-B., V.M., and J.S.-G. acknowledge financial support by the MICINN Spanish Ministry, (Project PID2019-108136RB-C32) and Generalitat Valenciana (Project PROMETEO/2020/063). F.Y. acknowledges funding from the Chinese Scholars Council, A.Y. from the Humboldt Foundation (Germany), and M.L.L from the National Council of Science and Technology of Mexico (CONACyT, Grant No. 708585)

“Tengo que sobrevivir”: Relato de vida de tres jóvenes microemprendedores bajo COVID-19

The health crisis caused by the COVID-19 pandemic transformed life in all areas. This context presents extraordinary conditions of uncertainty that can contribute to understanding the entrepreneurial phenomenon and its very particular dynamics under this adverse context. Under the qualitative paradigm, an investigation was designed with the objective of determining and analyzing the experiences of the entrepreneurs who started their operations in the months of April and May, when the health crisis was declared in Mexico. The life stories of two young entrepreneurs were analyzed and the results were contrasted with the findings of Maritz (2020) and Nicólas Martínez and Rubio Bañón (2020), highlighting the challenges they face in their contexts. The results suggest that youth, resilience, detection of opportunities and a positive vision of the future influenced their decision to start a business in such an adverse situation, and the literature review showed that they share motivations, challenges and limitations of other entrepreneurs in the world facing the COVID 19 pandemic. In addition to the above, it is considered that the inexperience of the subjects of this study means that these newly born businesses do not feel threatened by the crisis they face and even maintain positive expectations for the future.   Keywords: Entrepreneurs; Covid-19; micro business; context; entrepreneurial opportunities.La crisis sanitaria ocasionada por la pandemia del COVID-19, transformó la vida en todos los ámbitos. Este contexto presenta condiciones de incertidumbre extraordinarias que puede aportar a entender el fenómeno emprendedor y sus dinámicas tan particulares bajo este contexto adverso. Bajo el paradigma cualitativo se diseñó una investigación con el objetivo de determinar y analizar experiencias de los emprendedores que iniciaron sus operaciones en los meses de abril y mayo, momento en que se declaró la crisis sanitaria en México. Se analizaron los relatos de vida de tres emprendedores jóvenes y se contrastaron los resultados con los hallazgos de Maritz (2020) y Nicólas Martínez y Rubio Bañón (2020) destacando los retos que enfrentan en sus contextos. Los resultados sugieren que la juventud, resiliencia, detección de oportunidades y visión positiva del futuro incidieron en su decisión de emprender un negocio en una situación tan adversa, y la revisión de la literatura mostró que comparten motivaciones, retos y limitaciones de otros emprendedores en el mundo enfrentando la pandemia del COVID 19. Aunado a lo anterior, se considera que la inexperiencia de los sujetos de este estudio hace que estos negocios recién nacidos no se sientan amenazados por la crisis que enfrentan e incluso mantienen expectativas positivas del futuro.   Palabras clave: Emprendedores; Covid-19; microempresa; contexto; oportunidades emprendedoras

Effect of Chronic L-Dopa or Melatonin Treatments after Dopamine Deafferentation in Rats: Dyskinesia, Motor Performance, and Cytological Analysis

The present study examines the ability of melatonin to protect striatal dopaminergic loss induced by 6-OHDA in a rat model of Parkinson's disease, comparing the results with L-DOPA-treated rats. The drugs were administered orally daily for a month, their therapeutic or dyskinetic effects were assessed by means of abnormal involuntary movements (AIMs) and stepping ability. At the cellular level, the response was evaluated using tyrosine hydroxylase immunoreactivity and striatal ultrastructural changes to compare between L-DOPA-induced AIMs and Melatonin-treated rats. Our findings demonstrated that chronic oral administration of Melatonin improved the alterations caused by the neurotoxin 6-OHDA. Melatonin-treated animals perform better in the motor tasks and had no dyskinetic alterations compared to L-DOPA-treated group. At the cellular level, we found that Melatonin-treated rats showed more TH-positive neurons and their striatal ultrastructure was well preserved. Thus, Melatonin is a useful treatment to delay the cellular and behavioral alterations observed in Parkinson's disease

Reference values for areal bone mineral density among a healthy Mexican population

Objective. Compare the influence of ethnicity in the prevalence of osteopenia and osteoporosis in various Mexican populations using two normal dual X-ray absorptiometry (DXA) reference databases: manufacturer¿s incorporating US Hispanic population and a normal mestizo Mexican population. Material and Methods. MMP included 9 946 subjects participating in an ongoing long-term cohort study focusing on lifestyle and chronic diseases, of which 6 487 MMP males and females aged 7 to 80 years were the normal subjects used to determine bone density T- and Z-scores, following WHO criteria, and peak bone mass values. Abnormal bone mass density values estimated by the manufacturer's and peak bone mass reference values were compared. Results and Conclusions. Our results show that by using the manufacturer´s T-score values in the mestizo Mexican population we are underestimating the number of abnormal bone mass BMD populations

Entomopathogenic Nematodes: Biological Model of Studies with Anthelmintics

Anthelmintics used in animals to combat parasitic infections are mainly excreted in manure and cause negative effects on the environment and decomposers. Nematodes are associated with the rhizosphere; some are gastrointestinal parasites of animals, and others regulate insects and other arthropods (entomopathogenic nematodes) and are considered beneficial. The habitat and the similarities that exist among them give the opportunity to use nematodes as a biological model. The availability of target organisms is not always feasible; therefore, experimental studies with models similar to those of the target organisms are a possibility. In veterinary clinics, the study of drug susceptibility is a fundamental tool to monitor the development of resistance. To conserve the biodiversity of the environment, it is necessary to make adequate use of anthelmintics, avoid resistance to these pesticides and prevent the used products from damaging populations of beneficial organisms

Manganese Inhalation Induces Dopaminergic Cell Loss: Relevance to Parkinson’s Disease

Parkinson’s disease (PD) experimental models are crucial in the assessment of possible therapies. Nevertheless, even though PD was one of the first neurodegenerative conditions to be modeled, there are limitations such as spontaneous recovery; lack of bilateral damage, which is a PD characteristic; animal intensive care after neurotoxin administration; and ultrastructural and biochemical nonspecific alterations but mostly the neurodegenerative time course observed in humans. In this chapter, we investigated the effects of divalent and trivalent manganese inhalation on rats and mice to obtain a novel PD animal model inducing bilateral and progressive dopaminergic cell death. We found that after 5 or 6 months of inhalation, there was more than 70% decrease in the number of TH-immunopositive neurons, and these alterations are correlated with an evident motor performance deficits manifested as akinesia, postural instability, and action tremor. More interesting is the fact that these alterations were reverted with l-DOPA treatment, implying that the motor alterations are associated with nigrostriatal dopaminergic innervation, postulating new light for the understanding of manganese neurotoxicity as an appropriate PD experimental model. Our results are contributing to the development of a suitable PD animal model, reproducible, sensitive, time-efficient, and readily applicable behavioral tests