Betholletia excelsa Fruit: Unveiling Toughening Mechanisms and Biomimetic Potential for Advanced Materials.

Dry fruits and nutshells are biological capsules of outstanding toughness and strength with biomimetic potential to boost fiber-reinforced composites and protective structures. The strategies behind the Betholletia excelsa fruit mechanical performance were investigated with C-ring and compression tests. This last test was monitored with shearography and simulated with a finite element model. Microtomography and digital and scanning electron microscopy evaluated crack development. The fruit geometry, the preferential orientation of fibers involved in foam-like sclereid cells, promoted anisotropic properties but efficient energy dissipating mechanisms in different directions. For instance, the mesocarp cut parallel to its latitudinal section sustained higher forces (26.0 ± 2.8 kN) and showed higher deformation and slower crack propagation. The main toughening mechanisms are fiber deflection and fiber bridging and pullout, observed when fiber bundles are orthogonal to the crack path. Additionally, the debonding of fiber bundles oriented parallel to the crack path and intercellular cracks through sclereid and fiber cells created a tortuous path.

Microstructural features influencing the mechanical performance of the Brazil nut (Bertholletia excelsa) mesocarp.

Brazil nut (Bertholletia excelsa) fruits are capable of resisting high mechanical forces when released from trees as tall as 50 m, as well as during animal dispersal by sharp-teethed rodents. Thick mesocarp plays a crucial part in seed protection. We investigated the role of microstructure and how sclereids, fibers, and voids affect nutshell performance using compression, tensile and fracture toughness tests. Fractured specimens were analyzed through scanning electron microscopy (SEM) and microtomography (microCT). Mesocarp showed high deformability (strain at max. stress of ~30%) under compression loading, a critical tensile strength of ~24.9 MPa, a Weibull modulus of ~3, and an elastic modulus of ~2 GPa in the tensile test. The fracture toughness, estimated through the work of fracture of SENB tests, reached ~2 kJ/m2. The thick and strong walls of mesocarp cells, with a weaker boundary between them (compound middle lamella), promote a tortuous intercellular crack path. Several toughening mechanisms, such as crack deflection, breaking of fiber bundles, fiber pullout and bridging as well as crack branching, occur depending on how fiber bundles and voids are oriented.

Hierarchical levels of organization of the Brazil nut mesocarp.

Aiming to understand Nature´s strategies that inspire new composite materials, the hierarchical levels of organization of the Brazil nut (Bertholletia excelsa) mesocarp were investigated. Optical microscopy, scanning electron microscopy (SEM), microtomography (MicroCT) and small-angle X-ray scattering (SAXS) were used to deeply describe the cellular and fibrillary levels of organization. The mesocarp is the middle layer of the fruit which has developed several strategies to avoid its opening and protect its seed. Fibers have a different orientation in the three layers of the mesocarp, what reduces the anisotropy of the structure. Sclereids cells with thick cell walls fill the spaces between the fibers resembling a foam-filled structural composite. The mesocarp has several tubular channels and fractured surfaces which may work as sites for crack trapping and increase toughness. The thick and lignified cell wall of sclereids and fibers and the weak interface between cells can promote a longer and tortuous intercellular crack path. Additionally, fibers with high strength and stiffness due to microfibrils oriented along the main cell axis (µ = 0° to 17°) were identified in the innermost layer of the mesocarp. Such an understanding of each hierarchical level can inspire the development of new cellular composites with improved mechanical behavior.

Process-related Changes in Polyetherimide Joined by Friction-based Injection Clinching Joining (F-ICJ).

This work presents a comprehensive study on the effects of the Friction-based Injection Clinching Joining (F-ICJ) process on the microstructure and local properties of the stake head. The manuscript evaluates the consequences on the quasi-static mechanical performance of hybrid joints of amorphous polyetherimide (PEI) with aluminium AA6082. Through an overlay of microhardness map on a cross-polarized transmitted-light optical microscopy (CP-TLOM) image, two lower-strength microstructural zones in the PEI stake head were observed: a plastically-deformed zone (PDZ) and a thermo-mechanically-affected zone (PTMAZ). When compared to the base material, PDZ and PTMAZ have a reduction of 12%-16% and 8%-12%, respectively, in local mechanical properties. The reduced local strength was associated with distinct volumes of loosely packed PEI chains with unsteady chain conformation and thus larger free volume in the affected regions. The mechanical strength reduction is reversible through physical aging by thermal annealing the joints, which additionally shows that process-induced thermomechanical degradation of PEI by chain scission, as evidenced by size exclusion chromatography (SEC) analysis, does not appear to affect local mechanical strength. An evaluation of typical loading regimes of staked joints in lap shear (average ultimate force of 1419 ± 43 N) and cross tensile (average ultimate force of 430 ± 44 N) testing indicates that the process-induced changes of PEI do not compromise the global mechanical performance of such a structure. These findings provide a better understanding of the relationships between processing, microstructure, and properties for further F-ICJ process optimization.

Equipamento de proteção individual auricular: avaliação da efetividade em trabalhadores expostos a ruído / Personal protective equipment headphones: evaluation of effectiveness in workers exposed to noise

RESUMO: Objetivo: avaliar a efetividade do uso de equipamento de proteção individual auricular (protetor auricular) de inserção, do tipo espuma moldável, em trabalhadores expostos a ruído, verificando se a sua utilização sem e com orientação sobre o seu uso adequado, proporciona a vedação necessária para a prevenção de agravos auditivos e extra-auditivos. Métodos: trata-se de um estudo pré-experimental descritivo, de corte transversal que utilizou o método quantitativo para a análise dos dados. Foram avaliados 75 trabalhadores (150 orelhas), com exposição a ruído ocupacional de diferentes setores e funções de várias empresas ou trabalhadores autônomos. Todos foram submetidos à audiometria tonal em três momentos distintos: i) para obtenção do limiar auditivo; ii) utilizando protetor auricular do tipo espuma moldável sem orientação sobre o seu uso adequado somente com as instruções contidas na embalagem; iii) usando o protetor auricular após orientação do fonoaudiólogo avaliador. Resultados: a comparação entre os valores obtidos na avaliação audiométrica com a utilização do protetor auricular, sem e com orientação do profissional fonoaudiólogo, revelou um ganho estatisticamente significante somente no caso de readaptação do dispositivo no conduto auditivo. Conclusão: a comparação entre as respostas evidencia uma maior efetividade e atenuação do protetor auricular, do tipo espuma moldável, após orientação adequada do fonoaudiólogo.

ABSTRACT: Purpose: to evaluate the effectiveness of the use of equipment of individual hearing protection (auricular protector) of insertion in workers exposed to noise, checking if its use with and without orientation about its adequate use, provides the necessary seal in the hearing impairment and extra-hearing impairment prevention. Methods: it is a descriptive pre-experimental study, of cross-sectional, which used a quantitative method for the data analysis. 75 workers were evaluated (150 ears), with exposure to occupational noise from different sectors and functions of several companies or self-employed workers. All of them were submitted to tonal audiometry in three distinctive moments: i) for obtaining the hearing threshold; ii) using auricular protector of the moldable foam type without orientation about its adequate use; iii) using the auricular protector after the orientation of the phonoaudiologist that evaluates. Results: the comparison between the values obtained in the audiometric evaluation with the use of auricular protector, with and without orientation of the professional phonoaudiologist, revealed a statistically significant gain only in the case of rehabilitation of the device in the auditory canal. Conclusion: the comparison between the answers evidences a higher effectiveness and attenuation of the auricular protector of the moldable foam type, after the adequate orientation of the phonoaudiologist.

Síndrome de Goldenhar: uma abordagem fonoaudiológica / Goldenhar Syndrome: speech-language approach

TEMA: o objetivo deste trabalho foi relatar o caso de uma criança portadora de Síndrome de Goldenhar em tratamento fonoaudiológico em uma clínica escola. PROCEDIMENTOS: foram coletados dados do prontuário do paciente, mediante assinatura do Termo de Consentimento Livre e Esclarecido e aprovação no Comitê de Ética da instituição, durante aproximadamente 11 meses de fonoterapia. Trata-se de uma criança de 5 anos e 11 meses de idade, do gênero masculino, apresentando ao nascimento má formação na orelha e no côndilo mandibular direitos, bem como espinha bífida. Para descrição do caso, antes e após o período de intervenção, o paciente passou por avaliações fonoaudiológicas como exame auditivo, do sistema estomatongático, medidas antropométricas faciais, exame articulatório, avaliação fonológica e da discriminação auditiva. RESULTADOS: observaram-se alterações como perda auditiva condutiva de grau moderado na orelha direita; alteração na mobilidade de lábios e língua; funções como deglutição, mastigação e respiração atípicas; medidas antropométricas faciais inferiores à normalidade, principalmente nos ramos mandibulares; bem como distúrbios na fala de ordem fonética (distorções) e fonológicas (dessonorizações). A partir de então, estabeleceu-se um planejamento terapêutico, com resultados positivos no período mencionado, principalmente no que se refere à função de mastigação. CONCLUSÃO: o paciente apresentou grande variedade de alterações fonoaudiológicas decorrentes do espectro oculoauriculovertebral, que se somatizam na associação com a respiração oral, os hábitos orais deletérios e os fatores ambientais que atuam no caso. Novos estudos mais aprofundados e com maior número de sujeitos são importantes na corroboração destes resultados.

BACKGROUND: the purpose of this paper is to tell the case of a child with Goldenhar Syndrome in speech-language treatment at a clinical school. PROCEDURES: data were collected from the patient's records, through signature of the Free and Clarified Consent Term and approval in the Ethics Committee of the institution, during approximately 11 months of treatment. This case relates a child with 5 years and 11 months old, male gender, with a birth malformation at the right ear and mandibular condyle, as well as spina bifida. For this description, the patient passed through evaluations of hearing, stomatognathic system, face anthropometric measures, articulation examination, phonological assessment and hearing discrimination, before and after intervention. RESULTS: we noted changes as for conductive hearing loss in a moderate degree at the right ear; modifications in the mobility of lips and tongue; alterations in deglutition, mastication and respiration; reduced face anthropometric measures, mainly at the mandibular ramus; as well as the articulatory (distortions) and the phonological disorders (devoicing). From these data, we set out a therapeutic planning, with positive results in the mentioned period, mainly as for the mastication function. CONCLUSION: the patient showed several speech-language alterations arising from the oculoauriculovertebral spectrum, that is being increased in the association with Mouth Breathing, the deleterious oral habits and the environmental factors of the patient. New studies with more details and higher number of subjects are important to corroborate such results.