The role of multi-walled carbon nanotubes in enhancing the hydrolysis and thermal stability of PLA.

Polylactic acid (PLA) is a bioresorbable and biodegradable polymer extensively used in various biomedical and engineering applications. In this study, we investigated the mass loss and thermal properties of PLA-multi-walled carbon nanotube (MWCNT) composites under simulated physiological conditions. The composites were prepared by melting PLA with 0.1, 0.5, 1.0, and 5.0 wt% MWCNTs using an ultrasonic agitator, and FTIR analysis confirmed composite formation. Subsequently, the composites were subjected to hydrolysis under simulated physiological conditions (pH 7.4 and 37 °C) for up to 60 days. The results revealed that the mass loss of the composites decreased with increasing MWCNT content, suggesting that the presence of MWCNTs decelerated the hydrolysis process. On day 58, the mass loss of pure PLA was 12.5%, decreasing to 8.34% with 0.1% MWCNT, 5.94% with 0.5% MWCNT, 4.59% with 1% MWCNT, and 3.54% with 5.0% MWCNT. This study offers valuable insights into the behavior of PLA-MWCNT composites under physiologically simulated conditions, facilitating the development of new polymer composites with enhanced thermal stability and degradation resistance for biomedical applications.

A continuous process in mixers-settlers for the removal/recovery of chromium in effluents from the tanning industry.

One of the main environmental issues caused by the tanning industry is given by the high concentration of chromium contained on its effluents. The removal of this pollutant has become a technological challenge. To solve this issue, this work proposes a continuous process based on mixers-settlers for the removal of the chromium present in effluents from the tanning industry. The process involves the use of liquid-liquid extraction systems. The study includes the development of isotherms for the removal and stripping, which are further represented through a mathematical model to determine the number of theoretical extraction stages and other operational variables. The results show that a better extraction is achieved in a system with two theoretical stages using Cyanex 272 as extractant, reaching more than 94% of removal of chromium with an extractant concentration of 0.32 mol/L. For stripping, sulfuric acid is used, obtaining a maximum recovery of 94%.

In Silico Study of Novel Cyclodextrin Inclusion Complexes of Polycaprolactone and Its Correlation with Skin Regeneration.

Three novel biomaterials obtained via inclusion complexes of ß-cyclodextrin, 6-deoxi-6-amino-ß-cyclodextrin and epithelial growth factor grafted to 6-deoxi-6-amino-ß-cyclodextrin with polycaprolactone. Furthermore, some physicochemical, toxicological and absorption properties were predicted using bioinformatics tools. The electronic, geometrical and spectroscopical calculated properties agree with the properties obtained via experimental methods, explaining the behaviors observed in each case. The interaction energy was obtained, and its values were -60.6, -20.9 and -17.1 kcal/mol for ß-cyclodextrin/polycaprolactone followed by the 6-amino-ß-cyclodextrin-polycaprolactone complex and finally the complex of epithelial growth factor anchored to 6-deoxy-6-amino-ß-cyclodextrin/polycaprolactone. Additionally, the dipolar moments were calculated, achieving values of 3.2688, 5.9249 and 5.0998 Debye, respectively, and in addition the experimental wettability behavior of the studied materials has also been explained. It is important to note that the toxicological predictions suggested no mutagenic, tumorigenic or reproductive effects; moreover, an anti-inflammatory effect has been shown. Finally, the improvement in the cicatricial effect of the novel materials has been conveniently explained by comparing the poly-caprolactone data obtained in the experimental assessments.

Poly-ε-Caprolactone-Hydroxyapatite-Alumina (PCL-HA-α-Al2O3) Electrospun Nanofibers in Wistar Rats.

Biodegradable polymers of natural origin are ideal for the development of processes in tissue engineering due to their immunogenic potential and ability to interact with living tissues. However, some synthetic polymers have been developed in recent years for use in tissue engineering, such as Poly-ε-caprolactone. The nanotechnology and the electrospinning process are perceived to produce biomaterials in the form of nanofibers with diverse unique properties. Biocompatibility tests of poly-ε-caprolactone nanofibers embedded with hydroxyapatite and alumina nanoparticles manufactured by means of the electrospinning technique were carried out in Wistar rats to be used as oral dressings. Hydroxyapatite as a material is used because of its great compatibility, bioactivity, and osteoconductive properties. The PCL, PCL-HA, PCL-α-Al2O3, and PCL-HA-α-Al2O3 nanofibers obtained in the process were characterized by infrared spectroscopy and scanning electron microscopy. The nanofibers had an average diameter of (840 ± 230) nm. The nanofiber implants were placed and tested at 2, 4, and 6 weeks in the subcutaneous tissue of the rats to give a chronic inflammatory infiltrate, characteristic foreign body reaction, which decreased slightly at 6 weeks with the addition of hydroxyapatite and alumina ceramic particles. The biocompatibility test showed a foreign body reaction that produces a layer of collagen and fibroblasts. Tissue loss and necrosis were not observed due to the coating of the material, but a slight decrease in the inflammatory infiltrate occurred in the last evaluation period, which is indicative of the beginning of the acceptance of the tested materials by the organism.

Hábitos de vida y rendimiento académico en periodo evaluativo en estudiantes de enfermería / Life Habits and Academic Performance during the Examination Period in Nursing Students

Introducción: Los hábitos de vida de los estudiantes universitarios, con poco tiempo para su realización debido al estrés académico, prácticas, horario de clase y estudio, suelen ser poco saludables, por tanto, pueden influir negativamente en el rendimiento académico. Objetivo: Analizar los hábitos de vida en periodo evaluativo y su influencia en el rendimiento académico en estudiantes universitarios del grado en enfermería. Métodos: Estudio observacional descriptivo de tipo transversal realizado en el momento del examen a 488 estudiantes de los cuatro cursos del grado en enfermería de una universidad al sur de España, en el curso académico 2018. Los instrumentos empleados fueron: un cuestionario con datos sociodemográficos y otro cuestionario de hábitos de estilo de vida. El análisis de la información se realizó través de estadísticos descriptivos, pruebas paramétricas y no paramétricas y correlación lineal. Se respetaron las consideraciones éticas para estudios con humanos. Resultados: El 53,30 por ciento de la muestra realizaba ejercicio físico de forma regular, siendo similar en los cuatro cursos evaluados para los hombres mientras que en las mujeres aumentó de 31,11 por ciento en 1º a 61,26 por ciento en 4º curso. No diferencias relevantes en el rendimiento académico según variables de estilo de vida excepto sueño. Conclusiones: Las horas de sueño dormidas, sobre todo la semana previa al examen se relacionan con mayor rendimiento académico. Nuestros resultados sugieren que los estilos de vida menos saludables conllevan a peor rendimiento académico(AU)

Introduction: The life habits of university students, with little time to carry them out due to academic stress, practices, class and study hours, are usually unhealthy; therefore, they can influence academic performance negatively. Objective: To analyze life habits in the evaluation period and their influence on academic performance in university students of the Nursing degree. Methods: Descriptive, cross-sectional and observational study carried out, in the academic year 2018, at the time of examination with 488 students from the four courses of the Nursing degree from a university in southern Spain. The instruments used were a questionnaire with sociodemographic data and another lifestyle habits quiz. Information analysis was carried out through descriptive statistics, parametric and nonparametric tests, and linear correlation. Ethical considerations for human studies were respected. Results: 53.30 percent of the sample did physical exercise on a regular basis, being similar for men in the four courses assessed, while for women it increased from 31.11 percent in first academic year to 61.26 percent in the fourth academic year. There were no relevant differences in academic performance according to lifestyle variables except sleep. Conclusions: The hours of sleep per se, especially during the week before the exam, are related to higher academic performance. Our results suggest that less healthy lifestyles lead to poorer academic performance(AU)

Epithelial Growth Factor-Anchored on Polycaprolactone/6-deoxy-6-amino-ß-cyclodextrin Nanofibers: In Vitro and In Vivo Evaluation.

Polycaprolactone (PCL) is a well-known FDA approved biomaterial for tissue engineering. However, its hydrophobic properties limit its use for skin wound healing which makes its functionalization necessary. In this work, we present the fabrication and evaluation of PCL nanofibers by the electrospinning technique, as well as PCL functionalized with 6-deoxy-6-amino-ß-cyclodextrin (aminated nanofibers). Afterwards, epithelial growth factor (EGF) was anchored onto hydrophilic PCL/deoxy-6-amino-ß-cyclodextrin. The characterization of the three electrospun fibers was made by means of field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR); Confocal-Raman Spectroscopy were used for elucidated the chemical structure, the hydrophilicity was determined by Contact Angle (CA). In vitro cell proliferation test was made by seeding embryonic fibroblast cell line (3T3) onto the electrospun mats and in vivo studies in a murine model were conducted to prove its effectivity as skin wound healing material. The in vitro studies showed that aminated nanofibers without and with EGF had 100 and 150% more cell proliferation of 3T3 cells against the PCL alone, respectively. In vivo results showed that skin wound healing in a murine model was accelerated by the incorporation of the EGF. In addition, the EGF had favorable effects in epidermal cell proliferation. The study demonstrates that a protein of high biological interest like EGF can be attached covalently to the surface of a synthetic material enriched with amino groups. This kind of biomaterial has a great potential for applications in skin regeneration and wound healing.

Polycaprolactone/Amino-ß-Cyclodextrin Inclusion Complex Prepared by an Electrospinning Technique.

Electrospun scaffolds of neat poly-ε-caprolactone (PCL), poly-ε-caprolactone/ß-cyclodextrin inclusion complex (PCL/ß-CD) and poly-ε-caprolactone amino derivative inclusion complex (PCL/ß-CD-NH2) were prepared by the electrospinning technique. The obtained mats were analyzed by a theoretical model using the Hartree⁻Fock method with an STO-3G basis set, and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), differential scanning calorimetry (DSC), confocal-Raman spectroscopy, proton nuclear magnetic resonance (¹HNMR) and contact angle measure (CA). Different mixtures of solvents, such as dimethylformamide (DMF)-tetrahydrofuran (THF), dichlormethane (DCM)-dimethyl sulfoxide (DMSO) and 2,2,2-Trifluoroethanol (TFE), were tested in the fiber preparation. The results indicate that electrospun nanofibers have a pseudorotaxane structure and when it was prepared using a 2,2,2-Trifluoroethanol (TFE) as solvent, the nanofibers were electrospun well and, with the other solvents, fibers present defects such as molten fibers and bead-like defects into the fiber structure. This work provides insights into the design of PCL/ß-CD-NH2 based scaffolds that could have applications in the biomedical field.

Recomendaciones de la Sociedad Latino Americana para el Estudio del Hombre Maduro (LASSAM) para la Prevención, Diagnóstico, Tratamiento y Monitoreo de la Andropausia o Hipogonadismo de Inicio Tardío / Recommendations of the Latin American Society for the Study of “advanced Man” (LASSAM) for the Prevention, Diagnosis, Treatment and Monitoring of the Andropause or Hypogonadism Start Late

Se espera que en el año 2050 la población de Latinoamericanos mayores de 65 años, sea de 184 millones, aumentando el número de incapacitados e inválidos por las enfermedades relacionadas con la edad, provocando un desastre social y económico si no se toman medidas preventivas urgentes y adecuadas. Se discuten las manifestaciones clínicas y bioquímicas del Hipogonadismo de Inicio Tardío (LOH), los efectos de la testosterona y otras hormonas (hormona de crecimiento, tiroxina, leptinas, etc.), su relación con la hiperplasia prostática y el cáncer de próstata (CaP), Osteoporosis, Síndrome Metabólico y la Obesidad. El uso de la testosterona mejora la calidad de vida de los hombres con LOH, alejando los efectos de las enfermedades degenerativas y las incapacidades relacionadas. El manejo del LOH es eminentemente multidisciplinario, tomando como referencia la seguridad prostática y la consulta urológica cuando se requiera, con un seguimiento por el médico de primer contacto, y la participación activa de las especialidades afines. Se emiten recomendaciones de diagnostico, tratamiento, monitoreo y prevención del LOH en el hombre Latino Americano, que deben ser adaptadas a cada caso.