This work presents the evaluation of iron oxide nanoparticles obtained from the aqueous extract of Eucalyptus grandis. Twenty-three experiments were carried out where the synthesis of nanoparticles was performed by using the aqueous extract together with salts of iron (II) chloride tetrahydrate and iron (III) chloride hexahydrate. A characterization was carried out by IR, TEM and BET, where bands were presented at 3,440.77, 1,559.26 and 445.31 cm⁻¹, indicating the presence of iron oxide nanoparticles. A relatively high monodispersity was evidenced with particles around 9 nm. By means of BET analysis it was found to present a surface area of 131.897 m²/g. Obtaining nanoparticles by this green method presents yield values of 98%, with application in nanotechnology, biomedicine, environmental treatment, among others, making them highly versatile and their production cost is relatively low.

One of the biggest environmental problems that has affected the planet is global warming, due to high concentrations of carbon (CO₂), which has led to crops such as coffee being affected by climate change caused by greenhouse gases (GHG), especially by the increase in the incidence of pests and diseases. However, carbon sequestration contributes to the mitigation of GHG emissions. The objective of this work was to evaluate the carbon stored in above and below ground biomass in four six-year-old castle coffee production systems. In a trial established under a Randomized Complete Block Design (RCBD) with the treatments Coffee at free exposure (T1), Coffee-Lemon (T2), Coffee-Guamo (T3) and Coffee-Carbonero (T4), at three altitudes: below 1,550 masl, between 1,550 and 2,000 masl and above 2,000 masl. Data were collected corresponding to the stem diameters of coffee seedlings and shade trees with which allometric equations were applied to obtain the carbon variables in the aerial biomass and root and the carbon variables in leaf litter and soil obtained from their dry matter. Highly significant differences were obtained in the four treatments evaluated, with T4 being the one that obtained the highest carbon concentration both in soil biomass with 100.14 t ha^-1 and in aerial biomass with 190.42 t ha^-1.

This paper mainly discusses the application and impact of AI tools in vocational college students' career planning and employment preparation in Chinese Mainland. Through a review and analysis of relevant literature, this article found that artificial intelligence tools can provide students with more information and assistance, thereby improving their career cognition and employment competitiveness. However, if artificial intelligence tools are not open to Chinese users or students overly rely on these tools, it may also bring some negative effects, such as job anxiety and decreased self-awareness. Therefore, the government and teaching departments should strengthen the education of career planning and employment preparation, improve the artificial intelligence system, establish personalized service mode and other measures to provide more comprehensive and personalized career recommendation and employment services for higher vocational students in Chinese Mainland.

This scholarly article aims at analyze the obstacles encountered by teachers who specialize in the transition from early childhood education to primary education, as well as the possible areas for their growth and progress. Through the utilization of a combination of qualitative and quantitative research methods, along with detailed case studies, we have identified a number of major challenges faced by these teachers. These challenges primarily center around psychological stress, disparities in educational philosophies, and the task of bridging the gap between home and kindergarten education. To promote the professional development of teachers specializing in this transition in the future, it is crucial to prioritize their mental well-being, implement policy reforms, and emphasize the importance of comprehensive qualities and innovative pedagogical approaches.