A Comprehensive Approach for Designing Low Carbon Wood Bio-Concretes.

This paper presents a method for designing low carbon bio-based building materials, also named bio-concretes, produced with wood wastes in shavings form (WS) and cementitious pastes. As the aggregates phase of bio-concretes is composed of plant-based particles, known as porous and high water-absorbing materials, the bio-concretes cannot be designed by using the traditional design rules used for conventional mortar or concrete. Then, the method used in the current paper is an adaptation of a previous one that has been developed in a recent paper where bio-concretes were produced with a cement matrix, three types of bio-aggregates, and a proposal of a design abacus. However, when that abacus is used for designing WBC with low cement content in the matrix, the target compressive strength is not reached. In the present paper, the method is extended to low cement content matrix (up to 70% of cement substitution) and also considering the greenhouse gas (GHG) emission of the WBC. To obtain data for proposing a new design abacus, an experimental program was carried out by producing nine workable WBCs, varying wood volumetric fractions (40-45-50%), and water-to-binder ratios. The bio-concretes produced presented adequate consistency, lightness (density between 715 and 1207 kg/m3), and compressive strength ranging from 0.64 to 12.27 MPa. In addition, the GHG emissions of the WBC were analysed through the Life Cycle Assessment methodology. From the relationships obtained between density, compressive strength, water-to-binder ratio, cement consumption, and GHG emissions of the WBC, calibration constants were proposed for developing the updated and more complete abacus regarding an integrated mix design methodology.

Validity of the estimated body fat percentage by bioimpedance and skinfolds in middle-aged and elderly women / Validez del porcentaje de grasa corporal estimado por bioimpedancia y pliegues cutáneos en mujeres de mediana edad y ancianas

Objectives: Verify the validity of electrical bioimpedance (BIA) and the skinfold method in estimating the percentage ofbody fat (% BF) in middle-aged and elderly women, using dual emission X-ray absorptiometry (DXA) as a reference method.Material and methods: The sample consisted of 106 volunteers (middle age, n = 58 [51.3 ± 4.9 years] and elderly, n = 48[67.2 ± 5.8 years]). The volunteers were submitted to anthropometric assessments and the % BF was subsequently calculatedusing the Jackson and Pollock 7 skinfold protocol (7SF). The % BF was also measured using BIA and DXA. Pearson’s correlation,Bland and Altman method, effect size and repeated-measure t-test were used to test the hypotheses.Results: Although there is a moderate positive relationship between the methods evaluated for middle-aged women (DXAvs 7SF, r = 0.67; DXA vs BIA, r = 0.62) and moderate to strong for the elderly (DXA vs 7SF, r = 0.57; DXA vs BIA, r = 0.75) (p ≤ 0.05in all analyzes), the agreement between the methods was weak (limits of agreement > ± 3.5%). Additionally, when assessingthe % BF mean using each method within the groups, it was observed that there was no significant difference between theestimates only between DXA and Pollock 7SF in the elderly group.Conclusion: Therefore, both the 7SF method and the BIA are not valid for estimating body fat in the sample evaluated. It isnecessary to develop equations for specific skinfolds to estimate the % BF of middle-aged and elderly women and reviewthe equations used by the BIA.(AU)

Objetivo: Verificar la validez de la bioimpedancia eléctrica (BIA) y el método del pliegue cutáneo en la estimación delporcentaje de grasa corporal (% GC) en mujeres de mediana edad y ancianas, mediante la doble emisión de rayos X (DXA )como método de referencia.Material y método: La muestra estuvo formada por 106 voluntarias (mediana edad, n = 58 [51,3 ± 4,9 años] y ancianas, n= 48 [67,2 ± 5,8 años]). Las voluntarias fueron sometidas a evaluaciones antropométricas y, posteriormente, se calculó el %GC utilizando el protocolo de pliegues cutáneos Jackson y Pollock 7 (7PC). El% de GC también se midió usando BIA y DXA.La correlación de Pearson, el método de Bland y Altman, el tamaño del efecto y la prueba t de medida repetida se utilizaronpara probar las hipótesis.Resultados: Aunque existe una relación positiva moderada entre los métodos evaluados para mujeres de mediana edad (DXAvs 7PC, r = 0,67; DXA vs BIA, r = 0,62) y moderada a fuerte para las ancianas (DXA vs 7PC, r = 0,57 ; DXA vs BIA, r = 0,75) (p ≤ 0,05en todos los análisis), la concordancia entre los métodos fue débil (límites de acuerdo > ± 3,5%). Además, al evaluar la mediade % GC usando cada método dentro de los grupos, se observó que no hubo diferencia significativa entre las estimacionessolo entre DXA y Pollock 7PC en el grupo de ancianas.Conclusiones: Por tanto, tanto el método 7PC como el BIA no son válidos para estimar la grasa corporal en la muestra eva-luada. Es necesario desarrollar ecuaciones para pliegues cutáneos específicos para estimar el % GC de mujeres de medianaedad y ancianas y revisar las ecuaciones utilizadas por el BIA.(AU)