999 resultados para Wood material
Resumo:
PIXE (Particle Induce X-ray Emission spectrometry) was used for analysing stem bark and stem wood of Scots pine, Norway spruce and Silver birch. Thick samples were irradiated, in laboratory atmosphere, with 3 MeV protons and the beam current was measured indirectly using a photo multiplicator (PM) tube. Both point scans and bulk analyses were performed with the 1 mm diameter proton beam. In bulk analyses, whole bark and sectors of discs of the stem wood were dry ashed at 550 ˚C. The ashes were homogenised by shaking and prepared to target pellets for PIXE analyses. This procedure generated representative samples to be analysed, but the enrichment also enabled quantification of some additional trace elements. The ash contents obtained as a product of the sample preparation procedure also showed to be of great importance in the evaluation of results in environmental studies. Spot scans from the pith of pine wood outwards, showed clearly highest concentrations of manganese, calcium and zinc in the first spot irradiated, or 2-3 times higher than in the surrounding wood. For stem wood from the crown part of a pine this higher concentration level was found in the first four spots/mms, including the pith and the two following growth rings. Zinc showed increasing concentrations outwards in sapwood of the pine stem, with the over-all lowest concentrations in the inner half of the sapwood. This could indicate emigration of this element from sapwood being under transformation to heartwood. Point scans across sapwood of pine and spruce showed more distinct variations in concentrations relative to hearth wood. Higher concentrations of e.g. zinc, calcium and manganese were found in earlywood than in denser latewood. Very high concentrations of iron and copper were also seen for some earlywood increments. The ash content of stem bark is up to and order higher than for the stem wood. However, when the elemental concentration in ashes of bark and wood of the same disc were compared, these are very similar – this when trees are growing at spots with no anthropogenic contamination from the atmosphere. The largest difference was obtained for calcium which appeared at two times high concentrations in ashes of bark than in ashes of the wood (ratio of 2). Pine bark is often used in monitoring of atmospheric pollution, where concentrations in bark samples are compared. Here an alternative approach is suggested: Bark and the underlying stem wood of a pine trees are dry ashed and analysed. The elemental concentration in the bark ash is then compared to the concentration of the same element in the wood ash. Comparing bark to wood includes a normalisation for the varying availability of an element from the soil at different sites. When this comparison is done for the ashes of the materials, a normalisation is also obtained for the general and locally different enrichment of inorganic elements from wood to bark. Already a ratio >2 between the concentration in the bark ash and the concentration in the wood ash could indicate atmospheric pollution. For monitoring where bark is used, this way of “inwards” comparison is suggested - instead of comparing to results from analyses of bark from other trees (read reference areas), growing at sites with different soil and, locally, different climate conditions. This approach also enables evaluation of atmospheric pollution from sampling of only relative few individual trees –preferable during forest felling.
Resumo:
Silica based biomaterials, such as melt-derived bioactive glasses and sol-gel glasses, have been used for a long time in bone healing applications because of their ability to form hydroxyapatite and to stimulate stem cell proliferation and differentiation. In this study, bone marrow derived cells were cultured with bioactive glass and sol-gel silica, and seeded into porous polymer composite scaffolds that were then implanted femorally and subcutaneously in rats to monitor their migration inside host tissue. Bone marrow derived cells were also injected intraperitoneally. Transplanted cells migrated to various tissues inside the host, including the lung, liver spleen, thymus and bone marrow. The method of transplantation affected the time frame of cell migration, with intraperitoneal injection being the fastest and femoral implantation the slowest, but not the target tissues of migration. Transplanted donor cells had a limited lifetime in the host and were later eliminated from all tested tissues. Bioactive glass, however, affected the implanted cells negatively. When it was present in the scaffold no donor cells were found in any of the tested host tissues. Bioactive glass S53P4 was found to support both osteoblastic and osteoclastic phenotype of bone marrow derived cells, but it was resistant to the resorbing effect of osteoclastic bone marrow derived cells, showing that bioactive glass is rather dissolved through physicochemical reactions than resorbed by cells. Fast-dissolving silica sol gel in microparticulate form was found to increase collagen formation by bone marrow derived cells, while slow dissolving silica microparticles enhanced their proliferation, suggesting that the dissolution rate of silica controls the response of bone marrow derived cells.
Resumo:
A Embriologia Humana é de extrema importância na formação de profissionais de saúde, porém seu estudo, muitas vezes, é considerado desestimulante, decorativo e sem significado prático para muitos estudantes, tornando-se pouco efetivo. Este trabalho objetivou produzir material didático interativo com modelos embrionários representativos do desenvolvimento embrionário do sistema nervoso. Para avaliar de forma qualitativa a real efetividade e capacidade de facilitar o processo de ensino-aprendizagem no contexto da Aprendizagem Baseada em Problemas, o material foi aplicado aos estudantes da primeira série de Medicina e Enfermagem da Faculdade de Medicina de Marília. Os estudantes consideraram que o material contribuiu para o entendimento do tema e facilitou a visualização dos eventos embrionários, além de despertar o interesse pelo estudo da disciplina. O material serviu como recurso para sedimentar o conhecimento e suscitou nos estudantes a integração dos conhecimentos com outras disciplinas. Em termos qualitativos, a análise dos questionários dos estudantes indicou que o material didático produzido foi efetivo na aprendizagem e funcionou como recurso na aprendizagem autodirigida, favorecendo a diversificação de fontes de busca e sendo complementar a livros-texto e outros materiais teóricos.
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There are reasons of necessity in bio-fuel use and bio-energy fast development. It includes the material about bio-energy technologies, applications and methods. There are basic thermodynamics and economic theories. The economic calculation presents the comparison between two combinations. There are boiler plant below 20 MW in combination with ablative pyrolysis plant for bio-oil production and CHP plant below 100 MW in combination with the RTP pyrolysis bio-oil production technology. It provides a material about wood chips and bio-oil characteristics and explains it nature, presents the situation around the bio-fuel market or bio-fuel trade. There is a description of pyrolysis technologies such as ablative and RTP. The liquid product of the pyrolysis processes is bio-oil. The bio-oil could be different even of the same production process, because of the raw material nature and characteristics. The calculation shows advantages and weaknesses of combinations and obtained a proof of suppositions. The next thing, proven by this work is the fact that to get more efficiency from energy project it is good possibility to built plants in combinations.
Resumo:
As técnicas usuais empregadas no processamento de materiais herborizados são limitantes porque não permitem reproduzir um laminário permanente e porque o registro dos resultados é temporário. Em estudos de anatomia aplicada à taxonomia, muitas vezes, é necessário utilizar exsicatas. Este trabalho teve como objetivo testar a utilização de metacrilato (Historesin, Leica) na preparação e inclusão de material herborizado, visando a obtenção de laminário permanente. Foram utilizadas folhas de plantas herborizadas do gênero Senecio Tourn. ex L. (Asteraceae), previamente reidratadas em H2O e armazenadas em etanol 70%. As amostras foram desidratadas em série etanólica e submetidas à (1v:1v) mistura de AE 95% e resina pura. Durante a infiltração, com resina pura, o material foi submetido a vácuo durante 72 horas. Os blocos foram cortados em micrótomo de avanço automático, com navalhas de aço descartáveis, e os cortes foram corados com azul-de-toluidina (pH 4,0). As lâminas foram montadas em Permount. O laminário permanente obtido apresentou qualidade superior à dos produzidos pelas técnicas usuais, pois foi possível obter cortes seriados, com espessura determinada. Essa técnica possibilitou otimizar a obtenção de cortes, a partir de pequenos fragmentos de exsicatas.
Resumo:
Rakennusalalla kehitetään uusia materiaaleja ja rakennuslainsäädäntö muuttuu kiivaaseen tahtiin. Kilpailu alalla kiristyy ja tarvitaan uusia toimintatapoja rakentamisen kaikissa vaiheissa aina suunnittelusta toteutukseen. Puumuovikomposiitti on Suomessa uudehko rakennusmateriaali. Tässä työssä selvitetään tällä hetkellä voimassa olevien rakennusmääräysten ja standardien asettamia vaatimuksia puumuovikomposiittien käytölle rakentamisessa Suomessa sekä kehitetään omaa yritystoimintaa laatimalla oman yrityksen liiketoimintasuunnitelma. Tässä diplomityössä on laadittu puumuovikomposiittitalon rakennuslupapiirustukset ja selvitetty, kuinka Lappeenrannan rakennusvalvonta suhtautuu puumuovikomposiitin käyttöön kyseessä olevassa kohteessa rakennuslupahakemusvaiheessa. Suunnitellusta puumuovitalosta on pyydetty tarjoukset talotoimittajilta ja arvioitu puumuovikomposiitin käytön vaikutusta rakentamisen kokonaiskustannuksiin. Liiketoimintasuunnitelman laadinnassa on hyödynnetty aihealueeseen liittyvää kirjallisuutta ja julkaisuja yhdistäen niihin omia näkemyksiä ja ideoita.
Resumo:
The objective of this study was to verify the potential of SNAP III (Scheduling and Network Analysis Program) as a support tool for harvesting and wood transport planning in Brazil harvesting subsystem definition and establishment of a compatible route were assessed. Initially, machine operational and production costs were determined in seven subsystems for the study area, and quality indexes, construction and maintenance costs of forest roads were obtained and used as SNAP III program input data. The results showed, that three categories of forest road occurrence were observed in the study area: main, secondary and tertiary which, based on quality index, allowed a medium vehicle speed of about 41, 30 and 24 km/hours and a construction cost of about US$ 5,084.30, US$ 2,275.28 and US$ 1,650.00/km, respectively. The SNAP III program used as a support tool for the planning, was found to have a high potential tool in the harvesting and wood transport planning. The program was capable of defining efficiently, the harvesting subsystem on technical and economical basis, the best wood transport route and the forest road to be used in each period of the horizon planning.
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Termites are well -known for their capacity to damage and destroy wood and wood products of all kinds in the tropics and subtropics. A field test was undertaken to evaluate variations in wood consumption of Pinus sp. and three species of Eucalyptus by subterranean termites. The test consisted of wooden stakes of each species being initially submitted to water immersion for 0, 24, 48 and 72 h, and buried in the ground to natural infestation by subterranean termites for an exposure period of 30, 45 and 60 days. Three species of subterranean termites were identified: Heterotermes longiceps (Snyder), Coptotermes gestroi (Wasmann) (Isoptera: Rhinotermitidae), and Nasutitermes jaraguae (Holmgren) (Isoptera: Termitidae). This is the first record of occurrence of H. longiceps in the state of Rio de Janeiro. Although the wood-consumption rates were not correlated significantly with their wood densities, there was a tendency of the softwoods (E. robusta and Pinus sp.) to be more consumed by subterranean termites than the woods of intermediate hardness (E. pellita and E. urophylla). Among the eucalyptus, E. robusta showed to be more susceptible to attack by subterranean termites than E. pellita and E. urophylla
Resumo:
Seloste artikkelista: The volume and composition of dead wood on traditional and forest fuel harvested clear-cuts / Sini Eräjää ... [et al.] - Julkaisussa: Silva Fennica 44 (2010) : 2, s. 201-211.
Resumo:
O trabalho foi desenvolvido no setor de manufatura de painéis da Battistella Indústria e Comércio Ltda., localizada em Santa Catarina, e teve como objetivo a avaliação do processo produtivo de painéis, utilizando-se os princípios do balanço de material e do rendimento da matéria-prima. Além disso, pretendeu-se estabelecer uma metodologia para aplicação em outras indústrias madeireiras. Os dados foram obtidos através de visitas, aplicação de questionários e dados de escritório, e elaboraram-se equações e um fluxograma para representar o balanço de material. Concluiu-se que a indústria é integrada, representando vantagem competitiva. O balanço de material indicou que a atividade com maior potencial gerador de resíduos foi a preparação de sarrafos de madeira (55,71% do total de resíduos gerados). As atividades com maiores rendimentos foram a prensagem (97,44%), o seccionamento (93,92%), o esquadrejamento (93,51), o lixamento (90,97%) e a preparação de sarrafos (54,51%). O rendimento geral da manufatura foi de 63,16%, sendo os valores encontrados no trabalho similares aos da literatura. A metodologia desenvolvida para o trabalho é simples e pode ser aplicada em outras indústrias do setor madeireiro.
Resumo:
The use of 12-year-old Pinus tecunumanii (Eguiluz e Perry) grown in Colombia was evaluated for bleached kraft pulp production. Kraft pulps of kappa number 30 ± 1 were produced, and oxygen delignified and bleached to 90% ISO with ECF processes. The bleached pulps produced under optimum conditions were evaluated with regard to their strength properties. Pinus tecunumanii wood required low effective alkali charge to reach the desired kappa number and the unbleached pulp showed high oxygen delignification efficiency and bleachability when a OD(EO)DED sequence was used. The bleached pulps presented good physical-mechanical properties, which are comparable to those obtained with more traditional pines such as Pinus taeda and Pinus radiata. The results demonstrate that this tropical pine species is a suitable raw material for bleached kraft pulp production
Resumo:
One hundred different 5.5-year-old Eucalyptus grandis x Eucalyptus urophylla wood clones were cooked to kappa number 15-17.5 and the resulting kraft pulps oxygen-delignified to kappa 9.5-11.5 under fixed conditions, except for chemical charges. Thirteen samples showing large variations in effective alkali requirement, pulp yield and O-stage efficiency and selectivity were selected for brightness reversion studies. These samples were bleached to 90-91% ISO by DEDD and DEDP sequences and their brightness stability and chemical characteristics determined. Heat reversion of the eucalyptus kraft pulps was strongly influenced by the wood supply, with brightness loss varying in the range of 2.1-3.6 and 0.8-1.7 %ISO for ODEDD and ODEDP bleached pulps, respectively. Pulps bleached by the ODEDP sequence showed reversion values 1.3-1.9 % ISO lower than those bleached by the ODEDD sequence. Pulp carbonyl content decreased by 35-40% during the final peroxide bleaching stage. Carbonyl and carboxyl groups correlated positively with brightness reversion, as did permanganate number and acid soluble lignin. Pulp final viscosity and metal and DCM extractives contents showed no significant correlation with brightness reversion. Pulping, oxygen delignification and ECF bleaching performances also showed no correlation with brightness reversion.
Resumo:
The present work aimed to characterize and identify QTLs for wood quality and growth traits in E. grandis x E. urophylla hybrids. For this purpose a RAPD linkage map was developed for the hybrids (LOD=3 and r=0.40) containing 52 markers and 12 linkage groups. Traits related to wood quality and growth were evaluated in the QTL analyses. QTL analyses were performed using chi-square tests, single-marker, interval mapping and composite interval mapping analyses. All approaches led to the identification of similar QTLs associated with wood density, cellulose pulp yield and percentage of extractives, which were detected and confirmed by both the interval mapping and composite interval mapping methodologies. Some QTLs regions were confirmed only by the composite interval mapping methodology: percentage of soluble lignin, percentage of insoluble lignin, CBH and total height. Overlapping QTLs regions were detected, and these, can be the result of major genes involved in the regulation and control of the growth traits by epistatic interactions. In order to evaluate the effect of early selection using RAPD molecular data, molecular markers adjacent to QTLs were used genotype selection. The analysis of selection differential values suggests that for all the traits the phenotypic selection at seven years should generate larger genetic gains than early selection assisted by molecular markers and the combination of the strategies should elevate the selection efficiency.
Resumo:
As formigas cortadeiras (Atta e Acromyrmex) são consideradas importantes pragas na agricultura e silvicultura, mas pouco se sabe sobre os reais danos dessas espécies. Uma forma bastante difundida de avaliação do dano é por meio do cálculo da taxa de conversão, dividindo-se o peso do material cortado pelo peso de lixo produzido pelas colônias. Foi levantada a hipótese de que a qualidade do substrato cortado pode influenciar no forrageamento das operárias, alterando a taxa de conversão e dificultando as estimativas de dano. A taxa de conversão de oito colônias de Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae) foi calculada com duas espécies vegetais com diferentes concentrações de lignina e celulose, para testar essa hipótese. Colônias mantidas com folhas de baixa qualidade (razão lignina/celulose elevada) tiveram maior forrageamento e produziram mais lixo. Entretanto, a taxa de conversão das colônias foi semelhante com essas duas plantas (média = 1,54). Esse valor está dentro da variação encontrada para outras espécies no campo (1,5-1,8), indicando um fator semelhante de conversão entre os gêneros Atta e Acromyrmex. O consumo médio de material vegetal, em termos de pesos seco e fresco, de uma colônia de A. sexdens rubropilosa com 4.500 operárias, foi estimado em 520 e 1.100 g/ano, respectivamente.
Resumo:
Selluteollisuuden puunkäsittelylaitoksilla laitteiden kuluminen on prosessin luonteesta johtuen suurta ja kulumisen aiheuttamat kunnossapitokustannukset laitteiden elinkaaren aikana ovat huomattavia. Näissä olosuhteissa toimivan hakun osien kulumista on tutkittu ja tutkimusten pohjalta on kehitetty kulutusta kestäviä materiaalivaihtoehtoja. Vaihtoehtojen vertailut prosesseittain kuitenkin puuttuvat. Terävasteen osalta tutkimus- ja kehitystyötä on tehty vähän. Tässä diplomityössä selvitetään ja vertaillaan hakun kulutusosien kulumismekanismeja, osien materiaalivaihtoehtoja, valmistus- ja kunnostusmenetelmiä ja -kustannuksia laitteen elinkaaren aikana kolmessa erilaisessa puunkäsittelyprosessissa. Työssä annetaan suosituksia kuhunkin prosessiin ja kunnossapitostrategiaan parhaiten soveltuvista ratkaisuista. Työn Case-osuudessa tutkitaan uusia kulutusta kestäviä materiaalivaihtoehtoja terävasteelle. Case-tutkimuksen tuloksena löydettiin terävasteelle kolme uutta materiaalivaihtoehtoa sekä muita vaihtoehtoja, joiden käyttökelpoisuutta kannattaa tutkia lisää. Samalla saatiin terävasteelle parempaan laatuun pystyvä ja kilpailukykyisempi toimittaja. Tutkimuksen perusteella saatiin uusia suosituksia myös muiden kulutusosien materiaali- ja/tai pinnoitusvaihtoehdoiksi. Tuloksista voidaan mainita lisäksi, että kulutusosille löydettiin suositeltavimmat elinkaarikustannuksiltaan edullisimmat vaihtoehdot. Kulutusosien kunnostamiseen liittyen havaittiin, että kunnostaminen on kannattavaa yhtä poikkeusta lukuun ottamatta. Kunnostusprosessista löydettiin kehitettävää. Työn tuloksena saatiin myös useita uusia kehittämisideoita ja runsaasti suosituksia jatkotoimenpiteistä. Hakun kulutusosien nykytilasta saatiin hyvä käsitys ja kattava tietopaketti.