Efecto del ángulo microfibrilar en las características tecnológicas de la madera de Pinus pseudostrobus var. apulcensis

El ángulo microfibrilar es la inclinación de las microfibrillas de celulosa en la pared celular en relación al eje vertical de la célula. Esta característica contribuye en explicar las variaciones en propiedades físicas y mecánicas de la madera y fibra procesada. Pinus pseudostrobus var. apulcensis es una especie forestal nativa de México con importancia económica e industrial. Se seleccionaron al azar 10 árboles sanos de esta especie en una plantación en Texcoco, Estado de México, México. De cada árbol se extrajo un tarugo a 1,3 m de altura de fuste. Se midió el ángulo microfibrilar, la densidad básica (DB), la longitud de traqueidas  y la contracción volumétrica con el objetivo de determinar el efecto del ángulo microfibrilar sobre dichas características tecnológicas en esta madera. Se obtuvo un ángulo microfibrilar promedio de 28,8°; densidad básica promedio de 0,43 g·cm-3; longitud de traqueidas promedio de 3516 µm y contracción volumétrica promedio de 10,3 %.  Se ajustaron modelos aditivos generalizados entre el ángulo microfibrilar como variable explicativa y cada una de las tres variables respuesta por separado. Finalmente se ajustó un modelo aditivo generalizado para conocer el comportamiento de la densidad básica, longitud de traqueidas y contracción volumétrica en función del ángulo microfibrilar. Este modelo generado tuvo una capacidad explicativa de 88,2 %. La variable mejor explicada por el ángulo microfibrilar fue la longitud de traqueidas (capacidad explicativa de 83,3 %). Sería interesante observar si este comportamiento se presenta en otras especies de pino mexicanas

Xilotecnia of the wood of Acacia schaffneri from the state of hidalgo, Mexico

The genus Acacia spp belongs to the family Leguminosae, with more than 1300 species distributed naturally in all continents except Europe. In Mexico there are 85 species, of which 46 are endemic, most located in arid and semiarid regions, being Acacia coulteri and Acacia farnesiana the most widely distributed. The aim of this study was to determine the technological characteristics of the wood of Acacia schaffneri. To determine the anatomical characteristics, the methodology of Autonomous Chapingo University’s wood anatomy laboratory was used; for the physical properties, standards NOM EE-117-1981 and NMX-EE-167-1983 were used, and in calculating the mechanical properties the mathematical formulas were employed. The wood is reddish brown and has interlocked grain with diffuse porosity, aliform confluent parenchyma and in confluent bands, and crystals and gums. The proportion of cells was 11,87% vessel elements, 50,65% fibers 27,76% axial parenchyma and 9,81% ray parenchyma. Basic density was 880 kg/m3, tangential, radial, axial and volumetric shrinkage values were 10,57%; 4,97%; 0,10% and 15,82 % respectively, and fiber saturation point was 19,97%. The mechanical properties were very high, so it can be used in the manufacture of floors and in building constructions

Evaluación de dos barnices mediante intemperismo acelerado, aplicados en madera de plantaciones

Abstract: In this study, we determined the lifespans of two wood finishing systems, one water-based and another solvent-based, using an accelerated process of weathering. The varnishes used were both of the brand Polyform ® (Hydroform ® and 11000 ®). We applied these to wood of Cedrela odorata L. (red cedar) and Roseodendron donnell-smithii (Rose) Miranda (primavera) from commercial plantations of seven years in the state of Veracruz, Mexico. The lifespans of the varnishes were estimated with the Weibull cumulative distribution function. The varnish Hydroform® lasted 1.02 years on red cedar and 2.18 years on primavera, while the varnish 11000 ® lasted 3.70 years on red cedar and 8.99 years on primavera. According to the lifespans estimated for the two varnishes used in this study, we recommend using the varnish 11000 ® rather than Hydroform® for outdoor uses.Resumen: En este estudio se determinó la vida útil de dos sistemas de acabado, uno base agua y otra base solvente, mediante intemperismo acelerado. Los barnices empleados son de la marca comercial Polyform® (Hydroform® y 11000®). Se aplicaron en madera de Cedrela odorata L. (cedro rojo) y Roseodendron donnell-smithii (Rose) Miranda (primavera) provenientes de plantaciones comerciales de siete años del estado de Veracruz, México. La vida útil de los acabados se estimó con la función de distribución acumulativa del modelo Weibull. La vida útil para el barniz Hydroform® fue de 1.02 años en cedro rojo y 2.18 años en primavera, mientras que para el Barniz 11000® fue de 3.70 años en cedro rojo y 8.99 años en primavera. De acuerdo con el tiempo estimado de la vida útil de los acabados empleados en esta investigación, se recomienda utilizar el Barniz 11000® más que el Hydroform® en exteriores

Xilotecnia of the wood of "Acacia schaffneri" from the state of hidalgo, Mexico

The genus Acacia spp belongs to the family Leguminosae, with more than 1300 species distributed naturally in all continents except Europe. In Mexico there are 85 species, of which 46 are endemic, most located in arid and semiarid regions, being Acacia coulteri and Acacia farnesiana the most widely distributed. The aim of this study was to determine the technological characteristics of the wood of Acacia schaffneri. To determine the anatomical characteristics, the methodology of Autonomous Chapingo University’s wood anatomy laboratory was used; for the physical properties, standards NOM EE-117-1981 and NMX-EE-167-1983 were used, and in calculating the mechanical properties the mathematical formulas were employed. The wood is reddish brown and has interlocked grain with diffuse porosity, aliform confluent parenchyma and in confluent bands, and crystals and gums. The proportion of cells was 11,87% vessel elements, 50,65% fibers 27,76% axial parenchyma and 9,81% ray parenchyma. Basic density was 880 kg/m3, tangential, radial, axial and volumetric shrinkage values were 10,57%; 4,97%; 0,10% and 15,82 % respectively, and fiber saturation point was 19,97%. The mechanical properties were very high, so it can be used in the manufacture of floors and in building constructions

Wood anatomy of Fagus grandifolia subsp. mexicana (Fagaceae), endemic species from Mexico

Antecedentes y Objetivos: Fagus grandifolia subsp. mexicana habita en México, formando relictos en el bosque mesófilo de montaña en la Sierra Madre Oriental; es un taxón endémico que actualmente se encuentra en peligro de extinción. El objetivo del estudio fue describir las características anatómicas macroscópicas y microscópicas de la madera de Fagus grandifolia subsp. mexicana con el fin de contribuir a su conocimiento anatómico. Métodos: Las muestras de madera se obtuvieron mediante un método no destructivo que consistió en la extracción de núcleos del fuste de árboles vivos y trozos del tronco de un árbol derribado por el viento. La descripción anatómica de la madera se realizó en los planos tangencial, transversal y radial, a nivel macroscópico con tablillas (7×12×1 cm cortadas y pulidas) y microscópico con preparaciones fijas de cortes de los núcleos, de acuerdo con la terminología propuesta por la International Association of Wood Anatomists; también se estimaron los índices de vulnerabilidad (IV), agrupamiento de vasos (IVg) y mesomorfía (IM). Se empleó el programa RStudio para realizar las pruebas estadísticas y Excel para la estimación de los índices. Resultados clave: La madera de Fagus grandifolia subsp. mexicana es de color castaño claro, brillo medio a alto, veteado pronunciado, hilo recto y textura gruesa, posee porosidad difusa, placa de perforación simple y escalariforme (5-20 barras), punteaduras intervasculares opuestas, tílosis, traqueidas vasicéntricas, fibras libriformes, parénquima axial paratraqueal y apotraqueal difuso, radios heterocelulares uniseriados, biseriados, multiseriados y agregados, cristales prismáticos y cuerpos de sílice. Algunos rasgos anatómicos coinciden con los de otras especies del mismo género.Conclusiones: La descripción anatómica de la madera de F. grandifolia subsp. mexicana es la primera que se realiza para este taxón; además, contribuye a interrelacionar la información de sus características con las de otras especies de Fagus de importancia económica.Background and Aims: Fagus grandifolia subsp. mexicana inhabits Mexico, forming relict in the cloud forests of the Sierra Madre Oriental; it is an endemic taxon that is currently in danger of extinction. The aim of this study was to describe the macroscopic and microscopic anatomical features of the wood of F. grandifolia subsp. mexicana to contribute to its anatomical knowledge.Methods: The wood samples were obtained by a non-destructive method consisting of the extraction of cores from the stem of live trees and pieces of the trunk of one tree that recently had been felled by the wind. The anatomical description of the wood was made in the tangential, across, and radial planes, at the macroscopic level with wooden boards (7×12×1 cm section and polished) and microscopically with fixed slides of core sections. The anatomic description was made following the terminology by the International Association of Wood Anatomists. The Vulnerability index (VI), vessel grouping index (VIg), and mesomorphic index (MI) were also estimated. The RStudio program was used to perform the statistical tests and Excel to estimate the index.Key results: The wood of Fagus grandifolia subsp. mexicana is light brown colored, medium to high gloss, veining pronounced, straight grained and coarse texture, with diffuse porosity, simple and scalariform perforation plates (with 5-20 bars), opposite intervascular pits, tylosis, vasicentric tracheids, libiform fibers, apotracheal axial parenchyma diffuse and apotracheal parenchyma, heterogeneous rays, ray width uniseriate, biseriate, multiseriate and aggregate rays, prismatic crystals and silica bodies. Some anatomical features coincide with those of other species of the same genus.Conclusions: The description of the wood anatomy of F. grandifolia subsp. mexicana is the first for this taxon. Furthermore, it contributes to interrelating the information on its characteristics with that of other Fagus species of economic importance

COVID-19 in hospitalized HIV-positive and HIV-negative patients : A matched study

CatedresObjectives: We compared the characteristics and clinical outcomes of hospitalized individuals with COVID-19 with [people with HIV (PWH)] and without (non-PWH) HIV co-infection in Spain during the first wave of the pandemic. Methods: This was a retrospective matched cohort study. People with HIV were identified by reviewing clinical records and laboratory registries of 10 922 patients in active-follow-up within the Spanish HIV Research Network (CoRIS) up to 30 June 2020. Each hospitalized PWH was matched with five non-PWH of the same age and sex randomly selected from COVID-19@Spain, a multicentre cohort of 4035 patients hospitalized with confirmed COVID-19. The main outcome was all-cause in-hospital mortality. Results: Forty-five PWH with PCR-confirmed COVID-19 were identified in CoRIS, 21 of whom were hospitalized. A total of 105 age/sex-matched controls were selected from the COVID-19@Spain cohort. The median age in both groups was 53 (Q1-Q3, 46-56) years, and 90.5% were men. In PWH, 19.1% were injecting drug users, 95.2% were on antiretroviral therapy, 94.4% had HIV-RNA < 50 copies/mL, and the median (Q1-Q3) CD4 count was 595 (349-798) cells/μL. No statistically significant differences were found between PWH and non-PWH in number of comorbidities, presenting signs and symptoms, laboratory parameters, radiology findings and severity scores on admission. Corticosteroids were administered to 33.3% and 27.4% of PWH and non-PWH, respectively (P = 0.580). Deaths during admission were documented in two (9.5%) PWH and 12 (11.4%) non-PWH (P = 0.800). Conclusions: Our findings suggest that well-controlled HIV infection does not modify the clinical presentation or worsen clinical outcomes of COVID-19 hospitalization

How do women living with HIV experience menopause? Menopausal symptoms, anxiety and depression according to reproductive age in a multicenter cohort

CatedresBackground: To estimate the prevalence and severity of menopausal symptoms and anxiety/depression and to assess the differences according to menopausal status among women living with HIV aged 45-60 years from the cohort of Spanish HIV/AIDS Research Network (CoRIS). Methods: Women were interviewed by phone between September 2017 and December 2018 to determine whether they had experienced menopausal symptoms and anxiety/depression. The Menopause Rating Scale was used to evaluate the prevalence and severity of symptoms related to menopause in three subscales: somatic, psychologic and urogenital; and the 4-item Patient Health Questionnaire was used for anxiety/depression. Logistic regression models were used to estimate odds ratios (ORs) of association between menopausal status, and other potential risk factors, the presence and severity of somatic, psychological and urogenital symptoms and of anxiety/depression. Results: Of 251 women included, 137 (54.6%) were post-, 70 (27.9%) peri- and 44 (17.5%) pre-menopausal, respectively. Median age of onset menopause was 48 years (IQR 45-50). The proportions of pre-, peri- and post-menopausal women who had experienced any menopausal symptoms were 45.5%, 60.0% and 66.4%, respectively. Both peri- and post-menopause were associated with a higher likelihood of having somatic symptoms (aOR 3.01; 95% CI 1.38-6.55 and 2.63; 1.44-4.81, respectively), while post-menopause increased the likelihood of having psychological (2.16; 1.13-4.14) and urogenital symptoms (2.54; 1.42-4.85). By other hand, post-menopausal women had a statistically significant five-fold increase in the likelihood of presenting severe urogenital symptoms than pre-menopausal women (4.90; 1.74-13.84). No significant differences by menopausal status were found for anxiety/depression. Joint/muscle problems, exhaustion and sleeping disorders were the most commonly reported symptoms among all women. Differences in the prevalences of vaginal dryness (p = 0.002), joint/muscle complaints (p = 0.032), and sweating/flush (p = 0.032) were found among the three groups. Conclusions: Women living with HIV experienced a wide variety of menopausal symptoms, some of them initiated before women had any menstrual irregularity. We found a higher likelihood of somatic symptoms in peri- and post-menopausal women, while a higher likelihood of psychological and urogenital symptoms was found in post-menopausal women. Most somatic symptoms were of low or moderate severity, probably due to the good clinical and immunological situation of these women