Phenol, chromium, and dyes are continuously dumped into water bodies; the adsorption of these contaminants on activated carbon is a low-cost alternative for water remediation. We synthesized activated carbons from industrial waste of palm oil seed husks (kernel shells), sawdust, and tannery leather scraps. These materials were heated for 24 h at 600, 700 or 800°C, activated at 900°C with CO2 and characterized by proximate analysis and measurement of specific surface area (Brunauer-Emmett-Teller (BET) and Langmuir), and microporosity (t-plot). Isotherms showed micropores and mesopores in activated carbons. Palm seed activated carbon showed the highest fixed carbon content (96%), and Langmuir specific surface areas up to 1,268 m2/g, higher than those from sawdust (581 m2/g) and leather scraps (400 m2/g). The carbons were applied to adsorption of Cr(VI), phenol, and methylene blue dye from aqueous solutions. Phenol adsorption on activated carbons was 78-82 mg/g; on palm seed activated carbons, Cr(VI) adsorption at pH 7 was 0.35-0.37 mg/g, and methylene blue adsorption was 40-110 mg/g, higher than those from sawdust and leather scraps. Activated carbons from palm seed are promising materials to remove contaminants from the environment and represent an alternative application for vegetal wastes instead of dumping into landfills.

La presente investigación permitió realizar un estudio de relación entre la Autoeficacia y la autoestima, motivación intrínseca y nivel educativo de la madre en estudiantes universitarios de ingeniería de la Universidad de Cartagena. La muestra estuvo compuesta por mil doscientos (1200) estudiantes entre 2016 y 2018. El instrumento utilizado para medir la Autoeficacia fue la Escala de Autoeficacia General creada por Baessler y Schwarcer (1996), para la autoestima se empleó la Escala de Autoestima de Rosenberg (1995), para la motivación intrínseca se empleó el "Inventario de autorregulación del aprendizaje" diseñado por Lindner, Harris y Gordon (1993) y para el nivel educativo de la madre se utilizó la encuesta. Al cruzar la variable dependiente Autoeficacia con las independientes autoestima, motivación intrínseca y nivel educativo de la madre se pudo realizar el diagrama de barras de correlación arrojando significancia estadística entre la autoeficacia con la motivación intrínseca y el nivel educativo de la madre a un nivel de confianza del 95% mientras que con la autoestima no arrojó significancia alguna.

The association between academic performance, attendance to classes, intrinsic motivation and gender in 950 students of the engineering programs of the University of Cartagena between 2014 and 2016 was analyzed. The survey was used to evaluate the academic performance from the dimensions: conceptual, procedural and global. Class attendance and gender was assessed by teacher survey. The intrinsic motivation was evaluated through the CEVEAPEU questionnaire, which was designed and validated by Gargallo et. al (2009). For the relationship analysis, the variables were crossed and the bar diagrams and the 2x2 contingency tables were constructed applying the Chi-Square independence test. The values 0.89 (academic performance) and 0.90 (CEVEAPEU) for the Cronbach's Alpha, allowed to validate the instruments used. The results indicate that there is a significant degree of statistical significance (p <0.05) between academic performance and intrinsic motivation (p = 0.0003) at a confidence level of 95%. This means that the intrinsic motivation associated with enthusiasm, self-awareness, perseverance, mental agility and self-control have a relevant impact on the academic performance of the engineering student at the University of Cartagena. No statistical significance could be verified between the academic performance and the gender of the students. Nor between academic performance and class attendance of engineering students of the University of Cartagena at a 95% level of confidence.

Como objetivo de la presente investigación se evaluó la significancia estadística entre el estilo de aprendizaje con la autoeficacia, los conocimientos previos y la motivación intrínseca de los estudiantes universitarios en la facultad de ingeniería de la Universidad de Cartagena, Colombia. La muestra estuvo compuesta por mil cien (1100) estudiantes entre los años 2017 y 2019. El instrumento utilizado para medir el Estilo de Aprendizaje fue el cuestionario de estilos de aprendizaje (CHAEA) diseñado por Honey-Alonso (1994). La Autoeficacia se evaluó mediante la Escala de Autoeficacia General definida por Baessler y Schwarzer (1996). Los conocimientos previos fueron evaluados por encuesta y la motivación intrínseca mediante el "inventario de autorregulación del aprendizaje" diseñado por Lindner, Harris y Gordon (1993). Con respecto a los hallazgos, al cruzar la variable dependiente Estilo de Aprendizaje, con las independientes: autoeficacia, conocimientos previos y motivación intrínseca, se pudo constatar que existe significancia estadística entre el estilo de aprendizaje con la autoeficacia y la motivación intrínseca de os estudiantes de ingeniería a un nivel de confianza del 95%, mientras que con los conocimientos previos no existe significancia estadística alguna en la muestra analizada.

Se realizó un análisis de las causas que afectan el proceso de enseñanza-aprendizaje en el área de la química en cinco programas de ingeniería de la Universidad de Cartagena, encontrando que este problema ha ocasionado aumento en la deserción estudiantil en la facultad de ingeniería de la Universidad de Cartagena durante los últimos años. Esta investigación fue desarrollada  en tres (3) fases en  las cuales se realizaron encuestas a un número estimado de mil doscientos cincuenta  (1250) estudiantes de los programa de Ingeniería de la Universidad de Cartagena a través de un instrumento de recolección de información denominado Inventario de  autorregulación para el Aprendizaje (SRLI), el cual  consta de cuatro (4) subescalas: ejecutiva, cognitiva, motivación y control del ambiente,  las que estudiadas con los factores  internos: edad, sexo y motivación,   muestran  que el factor que tiene relevancia estadística relacionado con el SRLI es el factor  motivante a un nivel de confianza del 95%.

D3 and C2 TATP structures interconvert at room temperature. Herein, an easy method to isolate both conformers is shown that consists of multiple recrystallization steps using different solvent and heating to boiling. Spectroscopic and physical measurements, such as Raman spectroscopy, X‐ray diffraction, and melting point analysis, showed that clear and opaque crystals, respectively, represent different conformations of TATP. Additionally, the transition energy between both conformers was estimated using the Raman shifts.

The synthesis of molecules such as humic acids is a good strategy for the remediation of eroded soils. Since the synthesis and extraction of these carbon molecules do not represent a process of energy liberation of the carbon, it is also a low-cost process. Bad practices in soils, such as the indiscriminate use of pesticides and pesticides, cause damage to the soil that can be difficult to reverse, depending on the type of exposure and resilience they have. For example, the Atlantic coast is the most affected by salinization, according to Ideam a phenomenon related to incorrect agricultural activities, devastating tourism, and the impact of the dry climate. Soil erosion is an effect that has a negative influence on activities such as agriculture since the erosion of the soils prevents or causes the agricultural activity to be low or almost nil. Humic acids are molecules that can retain cations in their macroporous structure. Therefore, it is important to study what is the affinity that these macromolecules have with the cations of Zn, Ca, K, Mg and therefore, to know with which of them the affinity is greater depending on the type of carbon studied. The objective of this monographic study is to review the conceptual part of humic acids, their different forms of extraction, and their applications reported by different authors working in this field.

This study evaluated the effect of HS extracted from mineral coal on the growth of tomato (Solanum lycopersicum) and melon (Cucumis melo) plants to determine the role that humic substances (HS) play as promoters of plant growth. Three concentrations of HS were evaluated in 200 grams of soil. The fertilizer (urea 0.3%) and humic acid in concentrations of 0.05%, 0.1%, and 0.2% were added directly and at the same time to the amount of soil, using a control sample without the addition of humic acid. Increase measurements were made at three-day intervals up to 45 days. Plants treated with high concentrations of HS demonstrated a significant increase in roots (p>0.05). In both plants, the concentration of 0.2% in HS showed the greatest increase in growth, with the melon plant showing the greatest variation as time passed, with its highest peak in 36 days (13.1 ± 0.05cm) of the experiment, while in the tomato plant the maximum growth occurred in 30 days (9.2 ± 0.01 cm). The Dunnett test showed that there was no statistically significant difference between the control and the concentrations of 0.05% and 0.1% (p>0.05), while among the control and the soil sample with a concentration of 0.2% there was a statistically significant difference (p<0.05). The results show a notable influence of humic acid on the growth of the studied plants, especially at high concentrations. Keywords: fertilizer, horticulture, humic acid, soils.