Design, resistance, design load, assembly and user manuals of trusses fabricated with Gmelina arborea and Hieronyma alchorneoides wood from forest plantations trees in Costa Rica Two pratt-type trusses were constructed using Gmelina arborea (melina) and Hieronyma alchorneoides (pilón), designed with spans of 6 m and 9 m between bearings and using two types of joints: nails and screws. The trusses were subjected to bending loads in order to establish the resistance values to derive the design tables to be

The Giraúl granitic pegmatite field in Angola is composed of five pegmatite types, the most evolved belong to the beryl-columbite, beryl-columbite-phosphate and spodumene types. Pegmatites are concentrically zoned with increased grain size toward a quartz core; the most evolved pegmatites have well-developed replacement units. These pegmatites are rich in Nb-Ta oxide minerals and the field has a moderate interest for critical elements such as Ta and Hf. Tourmaline, garnet and micas occur as accessory minerals. The abundance of Zr and Nb-Ta minerals increases with the evolution of the pegmatites, as well as the proportions of beryl and Li-rich minerals. The Ta/(Ta + Nb) ratio in Nb-Ta oxide minerals and the Hf/(Hf + Zr) ratio in zircon also increase with the evolution of the pegmatites and within each pegmatite body from border to inner zones, and especially in the late veins and subsolidus replacements. Textural patterns and occurrence of late veins with Ta-rich minerals suggest that Nb and especially Ta can be enriched in late hydrothermal fluids exsolved from the magma, along with Hf and other incompatible elements as Sn, U, Pb, Sb and Bi.

Ultrasound is a reliable non-destructive method commonly used to evaluate the state of a piece of wood. The effect of the moisture content (MC) on the timber wave velocity, which is different depending on the wood species, must be considered. MC adjustment factors are important if accurate and comparable results are to be achieved. Thus, the goal of this study is to define a model that allows obtaining the adjustment factor to predict the standard velocity (12% of MC (V12) from velocity obtained at different MC for two Costa Rican commercial species: Tectona grandis L.F (teak) and Cupressus lusitanica M. (cypress). This effect was studied on small clean specimens during the desorption stages, from the fiber saturation point to the oven-dry state, controlling the specimen’s mass and MC on 62 specimens. With this data, the rate of change in ultrasound velocity per MC was modeled. Thus, the applicability of already published moisture adjustment models for conifers and hardwood tropical species was proved. The results showed that the proposed model coefficients adjust better than the ones obtained from the wood science literature, which makes them suitable to describe ultrasound velocity in different moisture conditions (VH).

The search for efficient and versatile structural elements, leads to the fabrication of I-joists (6.5 cm × 18.5 cm × 600 cm (width × depth × length) with glue-laminated bamboo (Guada angustifolia) in the flanges and Gmelina arborea 12-mm structural plywood in the web. The results showed a modulus of rupture (

IntroductionAn apnea episode is defined as the cessation of breathing for ≥15 seconds or as any suspension of breathing accompanied by hypoxia and bradycardia. Obtaining information about the respiratory system in a neonate can be accomplished using electromyography signals from the diaphragm muscle.ObjectiveThe purpose of this paper is to illustrate a method by which the respiratory and electrocardiographic signals from neonates can be obtained using diaphragmatic electromyography.Materials and methodsThe system was developed using single-supply, micropower components, which deliver a low-power consumption system appropriate for the development of portable devices. The stages of the system were tested in both adult and neonate patients.ResultsThe system delivers signals as those expected in both patients and allows the acquisition of respiratory signals directly from the diaphragmatic electromyography.ConclusionThis low-power system may present a good alternative for monitoring the cardiac and respiratory activity in newborn babies, both in the hospital and at home.SignificanceThe system delivers good signals but needs to be validated for its use in neonates. It is being used in the Neonatal Intensive Care Unit of the Hospital General de Medellín Luz Castro de Gutiérrez.