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In the present study, a simple and rapid reversed-phase HPLC method for the determination of astaxanthin in shrimp waste hydrolysate has been developed and validated. The analytical procedure involves the direct extraction of astaxanthin from the lipid fraction with methanol. The analytical column, SS Exil ODS, was operated at 25C. The mobile phase consisted of a mixture of water:methanol:dichloromethane:acetonitrile (4.5:28:22:45.5 v/v/v/v) at a flow rate of 1.0 mL/min. Detection and identification were performed using a photodiode array detector (lambda(detection) = 476 nm). The proposed HPLC method showed adequate linearity, repeatability and accuracy.

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La presente investigación tuvo como objetivo identificar los factores que afectan el rendimiento académico y determinar en qué medida el programa de tutorías coadyuva e impacta para la incorporación a la universidad y mejora del desempeño. El diseño fue exploratorio y correlacional, aplicando un instrumento (Alfa de Cronbach=0.8) a 186 universitarios mexicanos. Los resultados no demostraron diferencias significativas entre las características sociodemográficas y promedio universitario, aptitudes, actitudes y grado de satisfacción del curso tutorial. Sin embargo, se encontró una correlación significativamente positiva entre las sesiones de Tutorías vs índices de la dimensión Autoevaluación (0.225 a 0.352) por lo que los cursos de tutorías inciden indirectamente con el promedio universitario mediante el desarrollo de aptitudes y actitudes en el estudiante. Finalmente se sugiere la modificación periódica de los contenidos por otros que se adapten a las nuevas generaciones, a fin de atender las necesidades representadas con los índices más bajos.

Greenhouse gases emitted into the atmosphere by burning of fossil fuels cause global warming. One option is obtaining biodiesel. Nannochloropsis oculata was cultured under different light intensities and reactors at 25°C for 21 days with f/2 medium to assess their effects on cell density, lipid, and fatty acids (FAs). N. oculata improved cell density on fed‐batch glass tubular reactor (7 L) at 200 μmol E m−2 s−1, yielding 3.5 × 108 cells ml−1, followed by fed‐batch Erlenmeyer flask (1 L) at 650 μmol E m−2 s−1 with 1.7 × 108 cells ml−1. The highest total lipid contents (% g lipid × g dry biomass−1) were 44.4 ± 0.8% for the reactor (1 L) at 650 μmol E m−2 s−1 and 35.2 ± 0.2% for the tubular reactor (7 L) at 200 μmol E m−2 s−1, until twice as high compared with the control culture (Erlenmeyer flask 1 L, 80 μmol E m−2 s−1) with 21.2 ± 1%. Comparing the total lipid content at 200 μmol E m−2 s−1, tubular reactor (7 L) and reactor 1 L achieved 35.2 ± 0.2% and 28.3 ± 1%, respectively, indicating the effect of shape reactor. The FAs were affected by high light intensity, decreasing SFAs to 2.5%, and increased monounsaturated fatty acids + polyunsaturated fatty acids to 2.5%. PUFAs (20:5n‐3) and (20:4n‐3) were affected by reactor shape, decreasing by half in the tubular reactor. In the best culture, fed‐batch tubular reactor (7 L) at 200 μmol E m−2 s−1 contains major FAs (16:0; 38.06 ± 0.16%), (16:1n‐7; 30.74 ± 0.58%), and (18:1n‐9; 17.15 ± 0.91%).

This work presents the morphology and characterization of chitosan nanoparticles crosslinked with lecithin in the form of nano-onions obtained by an easy, economical, and possibly scalable method from a polymeric precursor known as chitosan. The creation of new products by using shrimp waste is a fundamental factor in avoiding water pollution. These materials have a positive impact as they add value to waste, and they provide the opportunity to decrease pollution. Chitosan nano-onions were synthesized by an environmentally friendly, easy, and inexpensive method using chitosan as a natural source. Chitosan nano-onions (CSNO) were characterized by using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) and specific surface area (SSA). The nano-onions characterization obtained by FTIR shows the presence of carbonyl groups at a wavenumber of 1752.12 cm–1, while the phosphate groups attributed to lecithin are observed at 1156.88 cm–1. XRD analysis confirmed an amorphous structure, while SEM images presented a globular morphology with concave surfaces. TEM analysis showed that the nano-onions are congregated in a unique structure that includes nanotubes. The CSNO average diameter by DLS was 442.5 nm with an octagonal arrangement, and a polydispersity index (PDI) of 0.532 and 31.9 mV. The average size of CSNO, the PDI, and the value of zeta potential were indicators of a stable dispersion with a specific superficial area measured by the Brunauer-Emmett-Teller (BET) method of 1.4 m2 g–1. The results of the chitosan-lecithin nano-onions characterization indicate changes in the surface of the material with a larger total surface area and pore structure, compared to that of pure chitosan. According to the results of the CHNO characterization, they could be used as adsorbents for contaminants and they also have a potential application in the biomedical area, mainly as drug encapsulation material.

This paper presents the design and validation of scales that can be used in project-based learning (PBL) when a small service company is studied, particularly the maturity of their business processes. The scales were designed based on an organization model with a systems approach. To validate the scales, data were collected by students through rubrics, after participating in a semesterlong PBL process developed for a university course. The reliability was determined and the factorial structure examined by an Exploratory Factor Analysis. Nine instruments were obtained as a final result of the project, in scoring rubric format that expresses four levels of maturity, from 16 attributes that comprehensively evaluate a process' maturity. The analysis revealed that the greatest scope for improvement in small businesses is in managing infrastructure and environment. The value of the proposed scales is because they offer a 2019 Journal of Management and Business Education 2(3), 250-278 PALABRAS CLAVEaprendizaje basado en proyectos (PBL), análisis organizacional, madurez de procesos, pequeñas empresas, análisis factorial exploratorio.

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