Research progress of occupational hazards in plywood manufacturing / 中华劳动卫生职业病杂志

Occupational disease hazards in plywood manufacturing mainly include wood dust, formaldehyde, phenol, ammonia, noise, terpene, microorganisms, etc. The exposure is complex with multiple factors accompanied or coexisted. In the production process, these factors are exceeded, and mass occupational disease hazard events occurred among workers. Exposure to wood dust, formaldehyde, terpene, etc., put workers at increased risk of cancer. This article provides a review of this issue in order to provide a scientific basis for the prevention and control of occupational disease hazards in plywood manufacturing.

Changes in chemical composition of cover crops residue during decomposition / Mudanças na composição química dos resíduos culturais de plantas de cobertura durante a decomposição

Crop residues decomposition are controlled by chemical tissue components. This study evaluated changes on plant tissue components, separated by the Van Soest partitioning method, during cover crop decomposition. The Van Soest soluble fraction was the first to be released from the crop residues, followed by cellulose and hemicellulose. Lignin was the crop residue component that suffered the least degradation, and for certain crop residue types, lignin degradation was not detected. The degradation of the main components of crop residues (soluble fraction, cellulose, hemicellulose and lignin) is determined by the chemical and structural composition of each fraction.

A decomposição de resíduos culturais é controlada pela composição química do tecido vegetal. O objetivo deste estudo foi avaliar as alterações que ocorrem nos componentes do tecido vegetal, separados pelo fracionamento de Van Soest, durante a decomposição de plantas de cobertura. A fração solúvel foi a primeira a ser liberada dos resíduos culturais, seguida pela celulose e hemicelulose. A lignina foi o componente dos resíduos culturais de menor degradação, sendo que em alguns resíduos culturais não foi possível detectar a degradação deste componente. A degradação dos principais componentes dos resíduos culturais (fração solúvel, celulose, hemicelulose e lignina) é determinada pela composição química e estrutural de cada uma destas frações.

Antimicrobial potential of pyroligneous extracts - a systematic review and technological prospecting

Abstract Pyroligneous extract is applied in diverse areas as an antioxidant, an antimicrobial, and an anti-inflammatory agent. The discovery of new cost-effective antimicrobial agents of natural origin remains a challenge for the scientific community. This study aimed to conduct a systematic review and a technological forecasting of the existent evidence regarding the use of pyroligneous extract as a potential antimicrobial agent. Studies were identified through an investigation of various electronic databases: PubMed, SciFinder, Web of Science, Scopus, Scielo, Google scholar, and ProQuest. Patents were searched through INPI, Google patents, Espacenet, Patents online, USPTO, and WIPO. The literature on antimicrobial activity of pyroligneous extract are limited given the short duration of studies and variability in study design, use of pyroligneous preparations, and reports on results. However, evidence suggests the potential of pyroligneous extract as a natural antimicrobial agent. The most studied activity was the role of PE as a food preservative. However, pyroligneous extracts are also effective against pathogenic bacteria in the oral microflora and treatment of candidal infections. Further research is needed using standardized preparations of pyroligneous extracts to determine their long-term effectiveness and ability as antimicrobial agents.

Natural decomposition of hornbeam wood decayed by the white rot fungus Trametes versicolor

ABSTRACT The impacts of white-rot fungi on altering wood chemistry have been studied mostly in vitro. However, in vivo approaches may enable better assessment of the nature of interactions between saprotrophic fungi and host tree in nature. Hence, decayed and sound wood samples were collected from a naturally infected tree (Carpinus betulus L.). Fruiting bodies of the white rot fungus Trametes versicolor grown on the same tree were identified using rDNA ITS sequencing. Chemical compositions (cellulose and lignin) of both sound and infected wood were studied. FT-IR spectroscopy was used to collect spectra of decayed and un-decayed wood samples. The results of chemical compositions indicated that T. versicolor reduced cellulose and lignin in similar quantities. Fungal activities in decayed wood causes serious decline in pH content. The amount of alcohol-benzene soluble extractives was severely decreased, while a remarkable increase was found in 1% sodium hydroxide soluble and hot water extractive contents in the decayed wood samples, respectively. FT-IR analyses demonstrated that T. versicolor causes simultaneous white rot in the hornbeam tree in vivo which is in line with in vitro experiments.

Microsatellite markers in candidate genes for wood properties and its application in functional diversity assessment in eucalyptus globulus

Background: Functional genetic markers have important implications for genetic analysis by providing direct estimation of functional diversity. Although high throughput sequencing techniques for functional diversity analysis are being developed nowadays, the use of already well established variable markers present in candidate genes is still an interesting alternative for mapping purposes and functional diversity studies. SSR markers are routinely used in most plant and animal breeding programs for many species including Eucalyptus. SSR markers derived from candidate genes (SSR-CG) can be used effectively in co-segregation studies and marker-assisted diversity management. Results: In the present study, eight new non reported SSRs were identified in seven candidate genes for wood properties in Eucalyptus globulus: cinnamoyl CoA reductase (CCR), homocysteine S-methyltransferase (HMT), shikimate kinase (SK), xyloglucan endotransglycosylase 2 (XTH2), cellulose synthase 3 (CesA3), glutathione S-transferase (GST) and the transcription factor LIM1. Microsatellites were located in promoters, introns and exons, being most of them CT dinucleotide repeats. Genetic diversity of these eight CG-derived SSR-markers was explored in 54 unrelated genotypes. Except for XTH2, high levels of polymorphism were detected: 93 alleles (mean of 13.1 sd 1.6 alleles per locus), a mean effective number of alleles (Ne) of 5.4 (sd 1.6), polymorphic information content values (PIC) from 0.617 to 0.855 and probability of Identity (PI) ranging from 0.030 to 0.151. Conclusions: This is the first report on the identification, characterization and diversity analysis of microsatellite markers located inside wood quality candidate genes (CG) from Eucalyptus globulus...

Chemical composition and natural durability of juvenile and mature heartwood of Robinia pseudoacacia L.

The aim of this study was to characterize the properties of juvenile and mature heartwood of Robinia pseudoacacia L. (black locust). The content, the composition, and subcellular localization of heartwood extractives were studied in 14 old-grown trees from forest sites in Germany and Hungary, as well as in 16 younger trees of four clone types. Heartwood extractives (methanol and acetone extraction) were analysed by HPLC-chromatography. UV microspectrophotometry was used to localize the extractives in the wood cell walls. The natural durability of juvenile and mature heartwood was analysed according to the European standard EN 350-1. Growth analyses, as well as the chemical analyses, showed that in Robinia the formation of juvenile wood is restricted to the first 10-15 years of cambial growth. In the heartwood high contents of phenolic compounds and flavonoids were present, which were in high concentrations in the cell walls of the axial parenchyma and of the vessels. In the juvenile heartwood, the content of these extractives is significantly lower than in the mature heartwood. In agree, the juvenile heartwood had a lower resistance to decay by Coniophora puteana (brown rot fungus) and Coriolus versicolor (white rot fungus) compared to the mature.

O objetivo deste estudo foi caracterizar as propriedades da região de cerne dos lenhos juvenis e adultos de Robinia pseudoacacia L. O conteúdo, a composição, bem como a localização subcelular dos extrativos foram estudados em 14 árvores de florestas de produção na Alemanha e na Hungria, assim como em 16 árvores de quatro tipos clone. Os extrativos (metanol e acetona extração) foram analisados por cromatografia-HPLC. O microespectrofotômetro de ultra violeta foi utilizado para localizar os extrativos nas paredes celulares da madeira. A durabilidade natural do lenho juvenil e adulto foi analisada de acordo com a norma europeia EN 350-1. Análises do incremento, bem como as análises químicas mostraram que, em Robinia a formação de lenho juvenil é limitada aos primeiros 10/15 anos de crescimento cambial. No cerne, elevados teores de compostos fenólicos e flavonóides foram encontrados e localizados em concentrações elevadas nas paredes celulares do parênquima axial e dos vasos. No cerno do lenho juvenil o conteúdo destes extrativos é significativamente menor do que no cerne do lenho adulto. o cerne do lenho juvenil apresentou menor resistência à degradação por Coniophora puteana (fungo de podridão parda) e Coriolus versicolor (fungo de podridão branca) em comparação com a madeira de lenho adulto.

Phagodeterrence by Quassia amara (Simaroubaceae) wood extract fractions on Hypsipyla grandella (Lepidoptera: Pyralidae) larvae

In Latin America and the Caribbean, precious wood species like mahoganies (Swietenia spp.) and cedars (Cedrela spp.) are seriously injured by the mahogany shootborer, Hypsipyla grandella (Zeller) (Lepidoptera: Pyralidae) larva, which bores into the main shoot of trees. In previous experiments focused on searching for a preventive method for managing this pest, a wood extract of bitterwood, Quassia amara L. ex Blom (Simaroubaceae) had been shown to cause phagodeterrence to larvae. Therefore, three fractions (water, methanol and diethyl ether) of a wood extract were tested for their phagodeterrence to larvae, by means of laboratory and greenhouse trials. Phagodeterrence was assessed by determining their effect on foliage consumption, mortality and signs of damage (number of orifices, sawdust piles, fallen shoots, number of tunnels and tunnel length) caused by larvae on Spanish cedar (C. odorata). Both the methanol and diethyl ether fractions caused phagodeterrence, by strongly reducing foliage consumption and signs of damage, while not causing larval mortality. The lowest concentration at which phagodeterrence was detected for the methanol fraction corresponded to 0.0625%, which is equivalent to a 1.0% of the bitterwood crude extract. However, results with the diethyl ether fraction were unsatisfactory, as none of the treatments differed from the solvent, possibly because of an adverse effect of the solvent on foliar tissues. Phagodeterrent principles from Q. amara derivatives may play an important role in dealing with H. grandella if they are complemented with other integrated pest management preventative tactics. Rev. Biol. Trop. 59 (1): 487-499. Epub 2011 March 01.

En América Latina y el Caribe, algunas especies que son fuente de maderas preciosas, como las caobas (Swietenia spp.) y cedros (Cedrela spp.), son seriamente dañadas por la larva de Hypsipyla grandella, la cual barrena el brote principal de los árboles. En experimentos previos orientados hacia la búsqueda de un método preventivo para manejar esta plaga, un extracto de la madera de hombre grande, Quassia amara (Simaroubaceae), había demostrado causar fagodisuasión a la larva. Por tanto, tres fracciones de un extracto de la madera de dicho árbol (agua, metanol y éter dietílico) fueron evaluadas en cuanto a su efecto fagodisuasivo sobre las larvas, mediante experimentos de laboratorio e invernadero. Dicho efecto se determinó según el consumo de follaje, la mortalidad y los signos de daño (número de orificios, montículos, brotes caídos, número y longitud de túneles) causados por las larvas en arbolitos de cedro amargo (C. odorata). Tanto la fracción de metanol como la de éter dietílico causaron fagodisuasión, pues redujeron fuertemente el consumo de follaje y los signos de daño, sin matar las larvas. La menor concentración de la fracción metanólica a la cual se detectó fagodisuasión correspondió a 0.0625%, la cual equivale al 1.0% del extracto crudo de hombre grande. Por su parte, los resultados con la fracción de éter dietílico fueron insatisfactorios, ya que ninguna de las concentraciones difirió del disolvente, quizás debido a un efecto adverso del mismo sobre los tejidos foliares. Los principios fagodisuasivos de los derivados Q. amara podrían jugar un papel importante para manejar a H. grandella, si fueran complementados con otras tácticas preventivas de manejo integrado de plagas.

Comparative evaluation among different materials to replace soft tissue in oral radiology studies

OBJECTIVE: The aim of this study was to establish which materials afford better simulation of soft tissues in Oral Radiology studies. MATERIAL AND METHODS: The sample was composed of four materials in eleven different thicknesses to simulate the soft tissues of the face. The mean values of the relative amounts of radiographic contrast of the materials were determined and compared to a gold standard value, which was obtained from 20 patients who were referred to have periapical radiographs taken of the left mandibular molars. Data were subjected to statistical analysis with Dunnett's test (p<0.05). RESULTS: The mean value of the relative amounts of contrast encountered in the patients was 0.47, with a range between 0.36 and 0.64 for all 44 material/thickness combinations. The majority of the tested materials showed values close to those of the patients' tissues, without statistically signifcant differences among them. The values of only three materials/thickness combinations differed statistically from those of the patients' tissues. CONCLUSIONS: Based on the results of the present study, it may be concluded that except for utility wax (4 mm and 8 mm) and water (4 mm), all materials tested at different thickness could be used as soft tissue substitute materials in Oral Radiology studies.

Antioxidant and cytotoxic activities of Caesalpinia pulcherrima wood.

Antioxidant and cytotoxic activities of the methanolic and aqueous extracts of Caesalpinia pulcherrima wood were studied in in vitro models. Both extracts exhibited strong antioxidant activity, as evidenced by the low IC50 values in both 1,1-diphenyl-2-picryl hydrazyl (DPPH), nitric oxide and superoxide scavenging methods; the values were found to be less or comparable to those of gallic acid, the standard used. To determine the cytotoxic activity, extracts were tested for toxic effects to brine shrimp larvae. In this assay, the methanolic extract had little effect, but aqueous extract was relatively toxic. The antioxidant and cytotoxic activities may be attributed to the total phenolic content in the wood.

A supramolecular proposal of lignin structure and its relation with the wood properties

In spite of the great importance of cellulose the lignin is considered the second most abundant substance of the wood. However, little attention has been given it, mainly to wood properties. The lignin as well as other structural compounds (cellulose and hemicelluloses), has obviously an important role on the wood properties, probably due its composition and existent bonds. In general lignins have β-O-4 (Alkyl Aril Ether) as majoritary bond. This bond in a continued structure form big molecules with spiral conformation as virtual model. Based on this idea, lignins that have high/low β-O-4 content may have differentiated spiraled structures,suggesting different behaviors on the wood properties,which shows that the lignins (Guaicyl:Syringyl (GS)) of angiosperms, for example, which have higher β-O-4 content would present higher spiral conformation than gymnosperms lignins(HG). On the other hand HG lignins have chance of being more anchored on the matrix compound than GS lignins. In this context, the β-O-4 bonds of lignins possibly affect the wood properties, therefore, it is considered relevant for wood technology science discussion.

Apesar da grande importância da celulose a lignina é considerada a segunda substância mais abundante da madeira. Entretanto, pouca atenção tem sido dada a ela, principalmente com relação às propriedades da madeira. A lignina assim como outras substâncias (celulose e hemicelulose), tem obviamente um papel importante sobre as propriedades da madeira, provavelmente devido a sua composição e a existências de ligações. Geralmente as ligninas possuem majoritariamente ligaçõesβ-O-4 (Éter Alquil-Arílico), esta ligação em uma estrutura contínua forma grandes moléculas com conformação em espiral, como visto em modelo virtual. Com base nesta idéia, ligninas que possuem alto/baixo teor de β-O-4, podem ter estruturas espiraladas diferenciadas, sugerindo comportamentos diferentes sobre as propriedades da madeira. Isto mostra que as ligninas de angiospermas ((Guaicílica:Siringilica) (GS)), que possuem mais alto teor de β-O-4, por exemplo, apresentariam uma conformação mais espiralar do que as ligninas de gimnospermas (HG). Por outro lado, as ligninas HG possuem mais chances de serem ancoradas sobre a substância matriz do que as ligninas GS. Neste contexto, ligações β-O-4 das ligninas afetam as propriedades da madeira, portanto, isto pode ser considerado relevante para discussão em ciência e tecnologia da madeira.

Characterization of chikusaku-eki and mokusaku-eki and its inhibitory effect on sapstaining fungal growth in laboratory scale

Chikusaku-eki and Mokusaku-eki are natural resources and acidic liquid by-products of bamboo and broad leaved trees charcoal burner. These products contain more than 200 ingredients, including phenols, poly phenols and acetic acids. These by-products were tested for their fungicidal activity against sapstaining fungi. There are no studies about the antifungal activity of Chikusaku-eki and Mokusaku-eki against wood staining fungi in the literature. According to the recent findings, this is the first report about the antifungal activity of Chikusaku-eki and Mokusaku-eki against wood staining fungi. These extracts were more effective against sapstaining fungi at minimum concentrations [0.10-1.0%] used in 2% [malt extract agar] medium. Three Chikusaku-eki [Chikusaku-eki-I, Chikusaku-eki-II and Chikusaku-eki-III] and 2 Mokusaku-eki [Mokusaku-eki-I, Mokusaku-eki-II] extracts were tested against 4 sapstaining fungal samples to evaluate the inhibition range on sapstaining fungal growth. Ophiostoma flexuosum, Ophiostoma tetropii, Ophiostoma polonicum and Ophiostoma ips were the sapstaining fungi used in this study against bamboo and wood extracts. The initial calibration of extracts was done by calculating the specific gravity, tar calculation and total organic content. The chloroform fractions of these extracts were analyzed by gas chromatography-mass spectrometry and both the extracts contained 2,6 dimethoxy phenol, dehydroacetic acid and 2,3,5 trimethoxytoluene. Results revealed that compounds of Chikusaku-eki and Mokusaku-eki markedly inhibited fungal growth at lower concentration. The Chikusaku-eki and Mokusaku-eki have both antifungal, antioxidant properties and a potential to be used as natural preservative in wood industries. Wood slice tests displayed the effective role of both extracts in laboratory level

Essential oil of trees of the genus Ocotea (Lauraceae) in Costa Rica. I. Ocotea brenesii

Se determinó la composición química de los aceites esenciales obtenidos de las hojas y de la madera del árbol Ocotea brenesii Standl., perteneciente a la familia Lauraceae, que crece en forma silvestre en Costa Rica. Para el estudio se utilizaron técnicas de cromatografía de gases capilar con detector de ionización de flama (GC/FID) y cromatografía de gases capilar acoplada a un detector de espectrometra de masas (GC/MS). Del aceite volátil de las hojas fueron identificados 64 constituyentes, que correspondieron a un 85.9% del aceite. Del aceite de la madera se identificaron 57 compuestos que correspondieron a un 69.0% del aceite. Los constituyentes mayoritarios que se identificaron en el aceite de las hojas fueron alfa-copaeno (21.1%), gamma-cadineno (9.2%), espatulenol (7.3%), globulol (5.6%) y beta-cariofileno (5.2%). Los constituyentes mayoritarios del aceite de la madera fueron alfa-copaeno (6.6%), óxido de cariofileno (6.3%), beta-cariofileno (6.1%) y el epóxido del humuleno (4.6%). La composición de los aceites es de naturaleza terpénica y no presentaron compuestos del tipo fenilpropanoide o bencenoide que son constituyentes característicos de la mayoría de los aceites de plantas del género Ocotea investigados anteriormente

The chemical composition of the essential oils from leaves and wood of Ocotea brenesii Standl. growing wild in Costa Rica was determined by capillary GC/FID and GC/MS. From the leaves, 4 compounds were identified, corresponding to 85.9% of the oil, and from the wood 57 compounds were identified corresponding to 69.0% of the oil. The major constituents identified in the leaf oil were alpha-copaene (21.1%), gamma-cadinene (9.2%), spathulenol (7.3%), globulol (5.6%) and beta-caryophyllene (5.2%). The major constituents of the wood oil were alpha-copaene (6.6%), caryophyllene oxide (6.3%), beta-caryophyllene (6.1%) and humulene epoxide (4.6%)