جستجوی مقالات مرتبط با کلیدواژه "” fungus”" در نشریات گروه "صنایع چوب و کاغذ"

Wood has some limitations in properties and applications due to its natural nature, which need to be modified. Wood modification is usually done with different aims and methods. One of the wood modification methods is thermal treatments in order to improvement of dimensional stability and biological resistance. But, it is surely affected on physical and mechanical properties of wood. Wood thermal modification in presence of oxygen causes the oxidation of its chemical structure which leads to decrement of physical and mechanical properties. Therefore, elimination of oxygen in thermal modification can reduce its destructive effects. In current study, the effect of thermo-oil process on the function of white rot fungus has been investigated. Moreover, the effect of this process on engineering properties of birch and pine wood species was evaluated.

In this study, two wood species of birch (Betula sp.) and pine (Pinus sp.) cut into the desired timbers. Heat treatment of the prepared timbers was carried out in a cylinder which equipped to the pressure and vacuum system. Also, industrial recycled oil was used for heat treatment of the timbers. The temperature and time treatment were considered 195 °C and 5 hours, respectively. At the end of the process, the used oil was drained into the oil storage tank and the timbers were removed from the cylinder after applying vacuum. In order to investigation of biological resistance as well as physical and mechanical properties (water absorption and swelling, density, mass loss, bending strength, compression strength parallel to the grain and impact strength) test specimens were prepared from the treated and control timbers based on the standard. The SPSS software was used for statistical analysis. The results were statistically analyzed based on a One-Way ANOVA method.

Results revealed that thermo-oil treatment can reduce the functionality of white rot fungus and also its efficiency on physical and mechanical properties of both wood species. Moreover, the results showed that this process improved the physical properties and reduced the mechanical properties, except compression strength parallel to the grain.

Thermo-oil treatment at high temperature causes structural changes of wood and affects its physical and mechanical properties. Also, the structural changes caused by heat treatment can be an effective and inhibiting factor to functionality of white rot fungus on physical and mechanical properties of wood.

 The purpose of this study was to investigate the effect of heat treatment on bio-durability and some physical and mechanical properties of beech (Fagus Sp.) and pine (Pinus Sp.). Thermo-wood samples were prepared from beech and pine species based on thermo-D process. Heat-treated and untreated wood specimens were evaluated after exposing to brown rot fungus for 16 weeks. The laccase activity and its effect on mass loss and wood density were investigated. Results showed that deterrence value of heat treatment on mass loss caused by brown rot fungus have been 76.92% and 44.32% in beech and pine wood, respectively. So, laccase activity and its efficiency on mass loss of control specimens was more than heat treated wood. The results also showed that thermally modification at high temperatures reduced wood density. However, it had deterrent effect on decrease of density caused by brown rot fungus activity. Moreover, some mechanical properties including impact strength and compression parallel to grain of wood specimens were measured. The results generally showed that thermal modification improves the bio-durability of both wood species. The results also revealed reduction of mechanical properties due to heat treatment except compression parallel to grain.

Book and documents damaged or contaminated by microorganisms are a serious threat to the health of users and librarians. This research was aimed to identify the different species of fungi in the archive of museums and their effects on manuscripts and also reviewing the possibility of transferring them to employees or vice versa. Method Current research was conducted in a field experiment. First the manuscripts (Aldoa, Resale Haj and Kholase Alfieh) were examined based on the visual effects of the fungal deterioration, then sampling was performed to cultivate and identify fungi under sterile conditions. Sabouraud dextrose agar medium was used for cultivation and finally, after 10 to 14 days, directs smears were prepared from grown colonies, and fungal genera were identified. the fungi were identified based on microscopic and morphological properties. The results of the studies showed that the fungi on the paper works in the archives of the Malek museum include Aspergillus flavus, Cladosporium, Acremonium, Trichophyton schoenleinii and Sterile hyphae, respectively. Aspergillus, Cladosporim and Acremonium fungi are common allergenic fungi which are identified in the libraries and can cause lung allergies in human. So these fungi can be dangerous for people who suffer from tuberculosis or background lung diseases. T.schoenleinii fungus is a pathogenic fungus in humans and is not common in books. This pathogenic fungus can be probably transferred to the manuscript by one of the librarians or a person who has frequently accessed to this book. Sterile hyphae are usually scattered in the surrounding and are not worth diagnosing and pathogenic.