Ballistic Performance of Guaruman Fiber Composites in Multilayered Armor System and as Single Target.

Multilayered armor systems (MAS) with a front ceramic layer backed by a relatively unknown Amazonian guaruman fiber-reinforced (Ischnosiphon koem) epoxy composites, as second layer, were for the first time ballistic tested against the threat of 7.62 mm rifle ammunition. The amount of 30 vol% guaruman fibers was investigated in three distinct configurations: (i) continuous aligned, (ii) 0-90° cross-laid, and (iii) short-cut randomly dispersed. Additionally, single-target ballistic tests were also carried out in the best MAS-performed composite with cross-laid guaruman fibers against .22 caliber ammunition. The results disclosed that all composites as MAS second layer attended the US NIJ standard with corresponding penetration depth of (i) 32.9, (ii) 27.5, and (iii) 29.6 mm smaller than the lethal limit of 44 mm in a clay witness simulating a personal body. However, the continuous aligned guaruman fiber composite lost structural integrity by delamination after the 7.62 projectile impact. By contrast, the composite with cross-laid guaruman fibers kept its integrity for subsequent shootings as recommended by the standard. The single-target tests indicated a relatively higher limit velocity for .22 caliber projectile perforation, 255 m/s, and absorbed energy of 106 J for the cross-laid guaruman fibers, which are superior to corresponding results for other less known natural fiber epoxy composites.

Degenerative Cervical Disorder-Stand-alone Cage Versus Cage and Cervical Plate: A Systematic Review.

STUDY DESIGN: Systematic review. OBJECTIVES: The objective of this study was to compare clinical and radiological outcomes following discectomy and anterior cervical fusion for the treatment of cervical degenerative disorder performed with stand-alone cages and anterior cervical plates. METHODS: Electronic searches were performed in the MEDLINE, LILACS, and Cochrane Systematic Reviews databases, according to PRISMA guidelines, with no language or date restriction. The review was registered in PROSPERO under number CRD42018109180. RESULTS: Six randomized clinical trials were selected, which evaluated at least one of the objectives of this work, such as pain control, bone consolidation, neurological symptoms, and cervical lordosis, thus satisfying the inclusion criteria. Articles that did not directly compare the 2 surgical techniques were excluded. A total of 309 patients were included and the results showed no significant difference in clinical (visual analogue scale and neck disability index) or radiological (cervical lordosis and fusion) outcome between the 2 groups. The operative time was shorter in the group with stand-alone cages (mean difference = -18.40; 95% CI = [-24.89, -11.92]; P < .66). CONCLUSION: The stand-alone cages and anterior cervical plate techniques have similar clinical and radiological outcomes. Despite the significantly shorter operative time for one group, other randomized clinical trials are needed to establish conclusive evidence in favor of one of the comparative treatments.

Comparison of furfural and biogas production using pentoses as platform.

Coffee cut-stems (CCS), a biomass with high lignocellulosic content, is a coffee crop waste after bean harvesting. The main application of this material is as fuelwood for farmers, disregarding their carbohydrate content for biotechnological processes. In these terms, this work aims to compare three process scenarios for the experimental valorization of C5 fraction from CCS to produce biogas and furfural with and without the ethanol production from remaining C6 fraction under biorefinery concept. Therefore, an experimental stage was performed to obtain these products, based on a previous diluted acid pretreatment. The hydrolysate fraction was used to produce furfural and biogas, achieving yields of 0.34 g of furfural/g xylose and 81.1 mL of CH4 per gram of volatile solids. Concerning the solid fraction after acid pretreatment, it was used to produce ethanol with a previous enzymatic hydrolysis. After fermentation, 0.47 g of ethanol/g of glucose (92% of the theoretical yield) was obtained. These experimental results were fed to simulation models in order to compare three scenarios in technical, economic and environmental terms. As the main results, from technical point of view, the biogas production presents the lowest energy requirements. From the economic perspective, the furfural production presents a prefeasibility at the base scale of processing (e.g., 12.5 ton h-1). Meanwhile, the biogas scenario needs a processing capacity >22.5 ton h-1 to achieve the economic prefeasibility. In the biorefinery case, the positive economic performance is found at processing scales above 83 ton h-1. This work concludes that the C5 sugars platform is identified as a potential alternative for the generation of furfural and biogas, however, in this case a multiproduct biorefinery system is not always the best option to valorize biomass given the very high scale required and the economic indicators.

Planning stand-alone electricity generation systems, a multiple objective optimization and fuzzy decision making approach.

This paper presents a fuzzy-multiple objective optimization methodology to plan stand-alone electricity generation systems. The optimization process considers three main objectives, namely technology cost, environmental and societal impacts. For each feasible solution of the Pareto set, a system reliability index is evaluated along the lifetime of the project. As a key contribution, the decision making process is carried out by applying a fuzzy satisfaction method (FSM). The FSM accounts simultaneously four key performance indexes (KPI): technical, economic, environmental and social. The novelty of the proposal lies on the inclusion of societal impact (local wealth creation) in the FSM used here to select the more appropriate solution. Previous contributions on FSM only accounts two of four indexes considered in this paper. The methodology was applied in a Colombian case study. The results show the importance of the simultaneous consideration of technical, economic, environmental and social objectives in the evaluation of off-grid energization solutions.