Synthesis of Pt and Pt-Fe nanoparticles supported on MWCNTs used as electrocatalysts in the methanol oxidation reaction

This work reports a feasible synthesis of highly-dispersed Pt and Pt-Fe nanoparticles supported on multiwall carbon nanotubes （MWCNTs） without Fe and multiwall carbon nanotubes with iron （MWCNTs-Fe） which applied as electrocatalysts for methanol electrooxidation. A Pt coordination complex salt was synthesized in an aqueous solution and it was used as precursor to prepare Pt/MWCNTs, Pt/MWCNTs-Fe, and Pt-Fe/MWCNTs using FeC12.4H20 as iron source which were named S 1, S2 and S3, respectively. The coordination complex of platinum （TOA）2PtC16 was obtained by the chemical reaction between （NH4）2PtC16 with tetraoctylammonium bromide （TOAB） and it was characterized by FT-IR and TGA. The materials were characterized by Raman spectroscopy, SEM, EDS, XRD, TEM and TGA. The electrocatalytic activity of Pt-based supported on MWCNTs in the methanol oxidation was investigated by cyclic voltammetry （CV） and chronoamperometry （CA）. Pt-Fe/MWCNTs electrocatalysts showed the highest electrocatalytic activity and stability among the tested electrocatalysts due to that the addition of ＂Fe＂ promotes the OH species adsorption on the electrocatalyst surface at low potentials, thus, enhancing the activity toward the methanol oxidation reaction （MOR）.

Nucleocytoplasmic Gynodioecy

We study the evolution of a gynodioecious species under mixed-mating through a nucleocytoplasmic male sterility model. We consider two cytoplasmic types and a nuclear locus with two alleles. Here, the interaction between one cytoplasmic type and a recessive nuclear male-sterility factor gives rise to only one female genotype, while the remaining types correspond to hermaphroditic plants. We include two fitness paramaters: the advantageous female fitness t of females relative to that of hermaphrodites;and a silent and dominant cost of restoration, that is, a diminished fitness for plants carrying a dominant restorer gene relative to that of hermaphrodites. The parameter related to the cost of restoration is assumed to be present on outcrossing male fertility only. We find that every population converges to a stable population. We also determine the nature of the attracting stable population, which could be a nucleocytoplasmic polymorphism, a nuclear polymorphism or another population with some genotypes absent. This depends on the position of t with respect to critical values expressed in terms of the other parameters and also on the initial population.

Impact of the Food Subsidy on the Academic Performance of Low-Income Primary Education Students in Mexico

The Program of Cocinas Comunitarias in the state of Oaxaca,Mexico benefits children aged 6 to 12 who attend primary education schools in low-income municipalities.It is hoped that this food assistance program will allow children to learn better and develop learning skills.In this way,a significant reduction in the grade failure rates and dropout rates is expected,which will be reflected in a higher graduation efficiency rates.In fact,the contribution of this work consists of a methodology for the analysis of the impact of the food subsidy on the academic performance of low-income primary education students.In this sense,a multivariate model was constructed to analyze the interrelationships between grade failure,dropout,graduation efficiency rates,food subsidy,and the socio-demographic characteristics of the population that attends primary education.The Mexican government expects from this program that the more low-income children complete primary education,the more likely that a higher number of adolescents will complete high school education.This scheme is very important for the country’s half population living in poverty and especially in Oaxaca State which is one of poorest states.

Subjective Well-Being Model for Urban Mexico and Applications

The purpose of this article is to contribute to the analysis of subjective well-being in the cities of Mexico through the theoretical formalization and empirical verification of a quantitative model.The variables come from the constructs of the self-reported well-being module(BIARE);and they are called:overall satisfaction with life,sense of fullness,affect balance,and satisfaction domains.The equations were constructed using ordinary least squares regression with the BIARE databases of 2014 and 2017.The analysis of the behavior pattern of variables conduced to findings of urban society’s expectations of well-being and concerns in the period analyzed.Variables quality of life-and-self-realization and overall satisfaction with life have the greatest weight in the model equations.Besides,it was determined that emotional balance and citizen security condition the model.Finally,a relevant finding was that religion restricts the sense of fulness since it represents a well-being project with an opposite logic.

Modeling Violence Among and Against University Students in a Mexican Medium-Sized City

Violence against university students and among them is analyzed on campus and the household as well as the relationships of violence between these two social spaces.The study was undertaken through an anonymous random survey in the two larger public universities in a Mexican medium-sized city.Overall violence and types of violence-verbal,psychological,sexual,and physical-were evaluated by sex and by universities;and the aggressors were identified.A students’concept of violence was built,considering causes of intimate-partner violence,violence in general and ethical judgment on gender violence.Finally,it was measured the relationships between violence on campus and in the household using bivariate statistical analysis.Findings indicate the main aggressors on campus are classmates and professors,whereas in the household are the mother,relatives together with the parents and relatives without the parents.On-campus,there were found statistically significant associations between professors-aggressors and students as victims of violence by sex.In the household,the bivariate analysis confirmed mothers as single aggressors and fathers exerting violence together with relatives against student-children;and direct relationships between on-campus(psychological and sexual violence)and domestic(physical and sexual violence).

Strategies of Mexican Rural Communities to Entry in the Local and Global Markets

This paper highlights the main features of the economy of rural households in Mexico and analyzes their strategiesto entry in local and global markets. It built a model of household economies using ordinary least squaresregression with data collected through a probabilistic survey in four communities. Especial care was taken to avoidmulticollinearity problems. The study communities are situated in Oaxaca state, Mexico in two contrasting climaticenvironments that present different conditions to access the markets. The resulting model not only identifies thehouseholds＇ market strategies but also measures the impact of households＇ decision-making about allocation ofresources on the household wellbeing. Contrary to the discourse on Mexico-US migration, this paper shows that therural households＇ labor for international migration is shrinking. A process of diversification of income sources isalready going on in rural areas, therefore, households rely increasingly on wages, family businesses, andgovernment transfers; besides, they complement their income with subsistence production and transfers from otherhouseholds. Finally, it was found that in some cases the simultaneous allocation of material and socio-demographicresources to economic activities and labor markets could restrict the increase in household wellbeing if thedemographic structure is already altered.

Productive Response of Pelibuey Sheep to Supplementation in the Stretching Season in the Dry Tropic

Sheep meat production in the dry tropics of Mexico is low in the dry season, due to lack of forage, therefore, strategic supplementation is important to avoid weight loss in animals;The research was carried out from August 15 to December 15, 2020 in order to evaluate the productive response of pelibuey sheep in confinement, fed with pangola grass hay (GH), plains grass silage (PGS) and supplemented with commercial feed (CF) in the dry season. 16 sheep of the same weight and age were used, four treatments were evaluated in them, in a completely random design;the treatments were four levels of supplement 0, 0.1, 0.2 and 0.3 kg of AC fed with HP and PGS. Sheep were dewormed at the beginning of the experiment and housed in individual cages. The variables were: dry matter intake, daily weight gain (DWG) and DM digestibility. DM consumption was different (P < 0.01), the lowest consumption was 0.364 kg in treatment 1 (T1), with a maximum of 0.684 kg in T4;WDG was different (P < 0.01), with a lower value of 0.044 kg·day-1 in T1 and a higher value of 0.112 kg in T4. The apparent digestibility of the dry matter showed a difference (P < 0.01) which varied from 45.52 to 59.15% for T1 and T4, respectively. DM intake, WL gain, and DM digestibility increased with increasing supplement level at the levels studied.

The potential of starch-chitosan blends with poloxamer for the preparation of microparticles by spray-drying

Using biopolymers as wall materials in spray drying poses challenges,particularly in attaining flowability and thermal stability among their physicochemical properties.This paper addresses these challenges by preparing microparticles using a blend of starch–chitosan and a poloxamer,commercially named Pluronic®F127.We aimed to elucidate the effects of varying poloxamer concentrations on the resulting particles through the spray drying technique.Blends with a poloxamer concentration of 3%(w/v)demonstrated a notably higher yield,especially when compared to those with 0%and 1%concentrations.Microparticles with 3%and 5%(w/v)poloxamer displayed a narrower particle size distribution,with the 3%blend showing a superior yield attributed to arrangements of blend components that improve flowability.X-ray diffraction analysis showcased the characteristic peaks of A-type starch form,with shifts suggesting enhanced interactions between components.Microparticles with increased poloxamer content showed elevated thermal degradation temperatures,with the 3%blend registering a significant rise,opening avenues for encapsulating heat-sensitive bioactive.This study primarily focuses on the preparation and basic characterization of microparticles.It underscores the potential of blends with optimal poloxamer concentrations in microencapsulation,emphasizing further research to harness their capabilities thoroughly.