Lignin Structure and Wood Properties

The objective of this study was to understand the relationship between lignin structural organization and certain wood properties. Lignin, which constitutes 20-30% of the weight of all woody plants, functions as a binding and encrusting material in the cell wall, giving rigidity to the overall plant structure. More than 60% of all linkages in lignins isolated (Björkman) from Aspidosperma macro-carpum, Lophanthera lactescens, Gallesia gorazema, Peltogyne paniculata, and Aspidosperma polyneuron were of the β-O-4 alkyl aryl ether type. This unit plays an important role in the physical and mechanical properties of wood. Percentages of β-O-4 unit were estimated by infrared spectroscopy. An Index of Molecular Flexibility (IMF) was introduced in order to hypothetically estimate the contribution of this unit toward wood flexibility, (under the assumption that the β-O-4 linkage is positively correlated with flexibility). Lignins from Aspidosperma macrocarpum (AM) and Aspidosperma poly-neuron (AP) show the highest and lowest structural complexity (diversity of linkage types β-β, β-5, β-O-4, etc.) with IMF values of 2.02 and 3.00, respectively. In this case, lignins AM and AP are supposedly contributing toward lowest and highest grade of wood flexibility, respectively, which demonstrates the hypothesis that β-O-4 linkages correlate well with flexibility

RELATIONSHIP BETWEEN WOOD DENSITY AND ANATOMY WITH DRILLING RESISTANCE BY NON-DESTRUCTIVE EVALUATION METHOD

The Resistograph has emerged as efficient non-destructive evaluation method, because it allows the fast assessment of mechanical resistance, density and other wood properties. The aim of the present study is to assess the influence of wood density and anatomy on resistance to resistographi drilling. Twenty trees of Eucalyptus grandis x Eucalyptus urophylla hybrids, at the age group of 6 years, whose chest height discs (CHD) were removed and subjected to diametrical strip drilling, were herein assessed. The critical locations of amplitude radius were selected after the visual analysis of the resistogram; it was done to remove samples for the anatomical analysis and density carried out to determine several moisture contents. Resistance to drill increased due to increased wood density. Person’s correlation between resistance to drill and basic density reached 0.67; density in hygroscopic moisture was 0.65. There was moderate correlation between fiber wall amplitude and thickness (r=0.65). Cell wall thickness, fiber length and lumen diameter were the main anatomical features contributing to higher resistance to resistograph drilling

Chemical changes of cell wall components of heat-treated wood / Alterações químicas dos componentes da parede celular de madeiras tratadas termicamente

The wood’s cell wall undergoes chemical modifications due to thermal action. The goal of this work was to analyze these changes in the Pinus caribaea var. caribaea and Khaya ivorensis, untreated and heat treated. The thermal treatment temperatures were 160° C, 180° C and 200° C, and the samples were then evaluated by Fourier transform infrared spectroscopy (FTIR). Fourier transform infrared spectroscopy analyzes were performed on samples with and without treatment, using a spectrometer in the Attenuated Total Reflectance (ATR) mode. The results were plotted in the Origin-Pro 8 program, obtaining comparison charts. In treated and untreated samples, the bands at ~1027cm-1 and ~3337cm-1 were more intense with increasing temperature. It suggests that the structural elements degraded, and small molecules were then obtained. It is concluded that the increase in temperature implied a greater absorption of infrared by the peaks related to cellulose, hemicelluloses, and lignin, indicating that they are undergoing changes

Wettability of the surface of heat-treated juvenile teak wood assessed by drop shape analyzer

This study investigated the effect of the heat treatment on the wettability of the surface of juvenile teak (Tectona grandis) wood assessed by drop shape analyzer. Heartwood and sapwood samples were heat-treated at 180 and 200oC. Contact angle measurements were done every 5 s for 120 s using a KRÜSS DSA100. Heartwood had lower wettability than sapwood. Heat-treatment decreased the surface wettability of both heartwood and sapwood, especially in the wood treated at 200oC. Heartwood had lower wettability than sapwood, even after heat treatment

Avaliação de adesivos à base de taninos de Pinus caribaea var. bahamensis e de Acacia mearnsii na fabricação de painéis aglomerados

http://dx.doi.org/10.5902/1980509814588This work aimed to evaluate the methods for extraction of tannin from the bark of Pinus caribaea var. bahamensis, as well as to evaluate the technical feasibility of using tannins from the barks of Pinus caribaea var. bahamensis, of Acacia mearnsii, the mixtures of black wattle and pine tannins and the mixture of adhesive urea formaldehyde (UF) with black wattle and pine tannins in the production of adhesives for particleboard. The barks of Pinus caribaea var. bahamensis were fragmented in hammer mill, sieved and extracted under reflux for 2 hours, using a bark: liquor relation of 1:15, in nine treatments. The best extraction was used to obtain large quantities of extracts, which were used in the manufacture of adhesives and mixtures with UF adhesive and tannins of black wattle and the manufacture of particleboard. The addition of sodium sulfite gave higher extraction of tannin, which was extracted with the addition of 5% sodium sulfite. The results showed that both the black wattle tannin, as the bark of Pinus caribaea var. bahamensis have good bonding properties. It is possible to add pine tannin solution to the solution of black wattle and to replace part of the UF adhesive for the wattle tannins up to 25%, without compromising the glue quality. Replacing 10% of UF for tannic extract, both pine and black wattle, did not alter the values of thickness swelling (TS) of the panels. It is possible to obtain good mechanical properties with UF adhesives modified with tannic extracts at a ratio of 10%. The high values found for the internal bond (IB) panels containing tannin extracts showed the potential of these tannic extracts for bonding wood materials.  http://dx.doi.org/10.5902/1980509814588Este trabalho teve por objetivo avaliar os métodos para a extração dos taninos da casca do Pinus caribaea var. bahamensis, assim como verificar a viabilidade técnica de utilização dos taninos da casca de Pinus caribaea var. bahamensis, de Acacia mearnsii, de misturas de taninos de acácia negra e pinus e de misturas do adesivo ureia-formaldeído (UF) com taninos de acácia e pinus na produção de adesivos para aglomerados. As cascas de Pinus caribaea var. bahamensis foram fragmentadas em moinho de martelo, peneiradas, extraídas sob refluxo, por 2 horas, utilizada uma relação casca:licor de 1:15 p:v, em nove tratamentos. A melhor forma de extração foi utilizada para obtenção de grandes quantidades de extratos, que foram utilizados na confecção de adesivos tânicos e nas misturas com adesivo UF e com taninos comerciais de acácia negra na fabricação de painéis aglomerados. A adição de sulfito de sódio proporcionou maior extração de taninos, sendo recomendável a extração com adição de 5% de sulfito de sódio. Os resultados mostraram que tanto os taninos de acácia, quanto os de Pinus caribaea var. bahamensis, apresentam boas propriedades de colagem. É possível a adição de solução tânica de pinus à solução tânica de acácia e também substituir parte do adesivo UF pelos taninos de acácia em até 25% sem comprometer a qualidade da colagem. A substituição de 10% de UF por extrato tânico, tanto de pinus quanto de acácia, não alterou os valores de inchamento em espessura (IE) dos painéis. É possível obter boas propriedades mecânicas com adesivos UF modificados com extratos tânicos na proporção de 10%. Os altos valores encontrados para ligação interna (LI) dos painéis fabricados com extratos tânicos evidenciaram o potencial desses taninos para colagem de painéis de madeira

PHYSICAL-MECHANICAL PROPERTIES OF BRIQUETTES PRODUCED FROM CHARCOAL FINES AND WASTE OF Pinus spp.

The objective of this research was to evaluate the physical and mechanical properties of briquettes produced with charcoal fines and waste of Pinus spp (sawdust and wood shavings). For the production, the charcoal fines of two particle sizes (less than and greater than 5 mm) were mixed with each type of wood waste of Pinus spp in the proportions of 5, 10, 15, and 20%. Then, the mixtures were compacted under the pressure of 55 kgf.cm-2 in a piston briquetter. As binder, 8% gelatinized maize starch was used. Tests were carried out on the briquettes in order to determine the apparent density, compressive strength, and friability index. Briquettes with the highest densities and compressive strengths were produced with the two lowest proportions of wood waste of Pinus spp (5 and 10%). The use of the charcoal fines combined with sawdust or wood shavings of Pinus spp is recommended for the production of briquettes with good physical and mechanical properties.The objective of this research was to evaluate the physical and mechanical properties of briquettes produced with charcoal fines and waste of Pinus spp (sawdust and wood shavings). For the production, the charcoal fines of two particle sizes (less than and greater than 5 mm) were mixed with each type of wood waste of Pinus spp in the proportions of 5, 10, 15, and 20%. Then, the mixtures were compacted under the pressure of 55 kgf.cm-2 in a piston briquetter. As binder, 8% gelatinized maize starch was used. Tests were carried out on the briquettes in order to determine the apparent density, compressive strength, and friability index. Briquettes with the highest densities and compressive strengths were produced with the two lowest proportions of wood waste of Pinus spp (5 and 10%). The use of the charcoal fines combined with sawdust or wood shavings of Pinus spp is recommended for the production of briquettes with good physical and mechanical properties

EVALUATION OF ADHESIVES BASED ON TANNINS FROM Pinus caribaea var. bahamensis AND Acacia mearnsii IN THE MANUFACTURE OF PARTICLEBOARD

Este trabalho teve por objetivo avaliar os m\ue9todos para a extra\ue7\ue3o dos taninos da casca do Pinus caribaea var. bahamensis, assim como verificar a viabilidade t\ue9cnica de utiliza\ue7\ue3o dos taninos da casca de Pinus caribaea var. bahamensis, de Acacia mearnsii , de misturas de taninos de ac\ue1cia negra e pinus e de misturas do adesivo ureia-formalde\ueddo (UF) com taninos de ac\ue1cia e pinus na produ\ue7\ue3o de adesivos para aglomerados. As cascas de Pinus caribaea var. bahamensis foram fragmentadas em moinho de martelo, peneiradas, extra\ueddas sob refluxo, por 2 horas, utilizada uma rela\ue7\ue3o casca:licor de 1:15 p:v, em nove tratamentos. A melhor forma de extra\ue7\ue3o foi utilizada para obten\ue7\ue3o de grandes quantidades de extratos, que foram utilizados na confec\ue7\ue3o de adesivos t\ue2nicos e nas misturas com adesivo UF e com taninos comerciais de ac\ue1cia negra na fabrica\ue7\ue3o de pain\ue9is aglomerados. A adi\ue7\ue3o de sulfito de s\uf3dio proporcionou maior extra\ue7\ue3o de taninos, sendo recomend\ue1vel a extra\ue7\ue3o com adi\ue7\ue3o de 5% de sulfito de s\uf3dio. Os resultados mostraram que tanto os taninos de ac\ue1cia, quanto os de Pinus caribaea var. bahamensis, apresentam boas propriedades de colagem. \uc9 poss\uedvel a adi\ue7\ue3o de solu\ue7\ue3o t\ue2nica de pinus \ue0 solu\ue7\ue3o t\ue2nica de ac\ue1cia e tamb\ue9m substituir parte do adesivo UF pelos taninos de ac\ue1cia em at\ue9 25% sem comprometer a qualidade da colagem. A substitui\ue7\ue3o de 10% de UF por extrato t\ue2nico, tanto de pinus quanto de ac\ue1cia, n\ue3o alterou os valores de inchamento em espessura (IE) dos pain\ue9is. \uc9 poss\uedvel obter boas propriedades mec\ue2nicas com adesivos UF modificados com extratos t\ue2nicos na propor\ue7\ue3o de 10%. Os altos valores encontrados para liga\ue7\ue3o interna (LI) dos pain\ue9is fabricados com extratos t\ue2nicos evidenciaram o potencial desses taninos para colagem de pain\ue9is de madeira.This work aimed to evaluate the methods for extraction of tannin from the bark of Pinus caribaea var. bahamensis, as well as to evaluate the technical feasibility of using tannins from the barks of Pinus caribaea var. bahamensis, of Acacia mearnsii , the mixtures of black wattle and pine tannins and the mixture of adhesive urea formaldehyde (UF) with black wattle and pine tannins in the production of adhesives for particleboard. The barks of Pinus caribaea var. bahamensis were fragmented in hammer mill, sieved and extracted under reflux for 2 hours, using a bark: liquor relation of 1:15, in nine treatments. The best extraction was used to obtain large quantities of extracts, which were used in the manufacture of adhesives and mixtures with UF adhesive and tannins of black wattle and the manufacture of particleboard. The addition of sodium sulfite gave higher extraction of tannin, which was extracted with the addition of 5% sodium sulfite. The results showed that both the black wattle tannin, as the bark of Pinus caribaea var. bahamensis have good bonding properties. It is possible to add pine tannin solution to the solution of black wattle and to replace part of the UF adhesive for the wattle tannins up to 25%, without compromising the glue quality. Replacing 10% of UF for tannic extract, both pine and black wattle, did not alter the values of thickness swelling (TS) of the panels. It is possible to obtain good mechanical properties with UF adhesives modified with tannic extracts at a ratio of 10%. The high values found for the internal bond (IB) panels containing tannin extracts showed the potential of these tannic extracts for bonding wood materials

Color stability of weathered heat-treated teak wood

This study investigated the color stability in a heat treatment of teak wood (Tectona grandis) exposed to ultraviolet radiation under accelerated aging conditions. Nine trees from three different spacing levels were used. Samples of 150 mm x 75 mm x 20 mm were prepared and divided into two groups: heartwood and sapwood. Two levels of heat treatment (180 and 200°C) were used. The color was measured every 42 hours with a portable spectrophotometer using the CIE-Lab system. Accelerated aging was performed in a QUV/Spray chamber. The total cycle of exposure to ultraviolet radiation was of 168 hours at 340 nm. Tree planting spacing had no effect on color change after ultraviolet radiation. Untreated sapwood had greater color change than untreated heartwood. However, after heat treatment, sapwood showed high color stability, especially at a temperature of 180°C

Avanços e perspectivas da RENAME após novos marcos legais:: o desafio de contribuir para um SUS único e integral

Objetivos: O presente artigo tem por objetivo descrever o processo de atualização da Relação Nacional de Medicamentos Essenciais (RENAME), contextualizando-o à luz de novos marcos legais do Sistema Único de Saúde (SUS). Métodos: Trata-se de um estudo descritivo, de natureza crítica-reflexiva, estruturado em dois momentos: a) o processo de atualização da RENAME com a instituição dos novos marcos legais e b) discussão dos avanços, desafios e perspectivas da RENAME com o advento dos marcos legais descritos. Resultados: Discute-se a nova concepção da RENAME e sua harmonização com as diretrizes do SUS, discorrendo sobre aspectos dos processos de incorporação, de responsabilização pelo financiamento e de pactuação interfederativa, e seus impactos no acesso aos medicamentos. Conclusões: As mudanças nos marcos legais contribuíram para a aproximação das políticas de incorporação tecnológica e de assistência farmacêutica no âmbito do SUS, tornando a nova RENAME um instrumento importante para a qualificação da gestão e para a garantia do acesso a medicamentos eficazes, efetivos e seguros à população brasileira. Descritores: Medicamentos Essenciais; Assistência Farmacêutica; Gestão em Saúde; Financiamento da Assistência à Saúde; Sistema Único de Saúde. &nbsp

Convalescent plasma for COVID-19 in hospitalised patients : an open-label, randomised clinical trial

Background: The effects of convalescent plasma (CP) therapy in hospitalised patients with coronavirus disease 2019 (COVID-19) remain uncertain. This study investigates the effect of CP on clinical improvement in these patients. Methods: This is an investigator-initiated, randomised, parallel arm, open-label, superiority clinical trial. Patients were randomly (1:1) assigned to two infusions of CP plus standard of care (SOC) or SOC alone. The primary outcome was the proportion of patients with clinical improvement 28 days after enrolment. Results: A total of 160 (80 in each arm) patients (66.3% critically ill, 33.7% severely ill) completed the trial. The median (interquartile range (IQR)) age was 60.5 (48–68) years; 58.1% were male and the median (IQR) time from symptom onset to randomisation was 10 (8–12) days. Neutralising antibody titres >1:80 were present in 133 (83.1%) patients at baseline. The proportion of patients with clinical improvement on day 28 was 61.3% in the CP+SOC group and 65.0% in the SOC group (difference −3.7%, 95% CI −18.8–11.3%). The results were similar in the severe and critically ill subgroups. There was no significant difference between CP+SOC and SOC groups in pre-specified secondary outcomes, including 28-day mortality, days alive and free of respiratory support and duration of invasive ventilatory support. Inflammatory and other laboratory marker values on days 3, 7 and 14 were similar between groups. Conclusions: CP+SOC did not result in a higher proportion of clinical improvement on day 28 in hospitalised patients with COVID-19 compared to SOC alone