Abstract
Methods to test the safety of wood material for hygienically sensitive places are indirect, destructive and limited to incomplete microbial recovery via swabbing, brushing and elution-based ...techniques. Therefore, we chose mCherry
Staphylococcus aureus
as a model bacterium for solid and porous surface contamination. Confocal spectral laser microscope (CSLM) was employed to characterize and use the autofluorescence of Sessile oak (
Quercus petraea
), Douglas fir (
Pseudotsuga menziesii
) and poplar (
Populus euramericana alba
L.) wood discs cut into transversal (RT) and tangential (LT) planes. The red fluorescent area occupied by bacteria was differentiated from that of wood, which represented the bacterial quantification, survival and bio-distribution on surfaces from one hour to one week after inoculation. More bacteria were present near the surface on LT face wood as compared to RT and they persisted throughout the study period. Furthermore, this innovative methodology identified that
S. aureus
formed a dense biofilm on melamine but not on oak wood in similar inoculation and growth conditions. Conclusively, the endogenous fluorescence of materials and the model bacterium permitted direct quantification of surface contamination by using CSLM and it is a promising tool for hygienic safety evaluation.
Some wood species have antimicrobial properties, making them a better choice over inert surfaces in certain circumstances. However, the organic and porous nature of wood raises questions regarding ...the use of this material in hygienically important places. Therefore, it is reasonable to investigate the microbial survival and the antimicrobial potential of wood via a variety of methods. Based on the available literature, this review classifies previously used methods into two broad categories: one category tests wood material by direct bacterial contact, and the other tests the action of molecules previously extracted from wood on bacteria and fungi. This article discusses the suitability of these methods to wood materials and exposes knowledge gaps that can be used to guide future research. This information is intended to help the researchers and field experts to select suitable methods for testing the hygienic safety and antimicrobial properties of wood materials.
The present investigation aimed to utilize a direct wood disc diffusion method to study the influence of plane of cutting, cutting method, sterilization method, and origin of tree on the ...antimicrobial activity of wood material. Six oak wood trees (
) were collected from 3 different locations in France. They were cut into 4 mm thick slices with either transverse (RT), tangential (LT) or radial (LR) faces. Round discs (diameter 9.95 ± 0.1 mm) were cut from the slices via a laser machine or a manual punch machine, and were sterilized with gamma irradiation (25 kGy) or autoclaving (121 °C). The antimicrobial activity of wood was tested using a direct diffusion method against
and
isolates. The zone of inhibition around the wooden disc was recorded following the recommendations used for antibiotics tests. The results showed that
was more susceptible than
, to the chemicals that diffused from the wood. The transverse face discs exhibited higher antimicrobial activity. Samples that had been sterilized by autoclaving showed significantly (
< 0.05) lower antimicrobial activity, whereas the cutting method and origin of tree did not influence the antimicrobial activity of wood material. Therefore, the choice of sterilization method and cutting planes must be taken into account while studying and interpreting the antibacterial properties of wood material.
Healthcare-associated infections (HAI) remain a burden in healthcare facilities, environmental surfaces being a potential reservoir for healthcare-associated pathogens. In this context, exploration ...of materials with potential antimicrobial activities represents a way forward for the future. Here, we explored the survival of four bacterial species commonly involved in HAI (Acinetobacter baumannii, Enterococcus faecalis, Klebsiella pneumoniae, Staphylococcus aureus), on oak versus three other materials (aluminum, polycarbonate, stainless steel). Twenty microliters of each bacterial suspension (approximatively 107 bacteria) were deposited on each material. Bacterial counts were measured by grinding and culturing on day 0, 1, 2, 6, 7 and 15. Analyses were performed in triplicate for each material and each time evaluated. It appeared that the bacteria viable count decreased rapidly on transversal and tangential oak compared with the other materials for all bacterial species. Furthermore, no difference was noticed between transversal and tangential oak. These results underline the potential for use of oak materials in healthcare facilities, a consideration that should be supported by further investigations.
A Review of Methods to Increase the Flexibility of Wood Irle, M.
Bulletin of the Transilvania University of Brașov. Series II, Forestry, wood industry, agricultural food engineering,
01/2020, Letnik:
12(61), Številka:
2
Journal Article
This paper provides a short review of the techniques that can be used to make flexible wood-based products. It also describes preliminary experiments on the potential of radial compression of French ...grown Poplar (Populus spp.) for the manufacture of highly flexible products. A 50% uniaxial compression strain was applied to wood blocks with an average moisture content of 15.5%. The blocks were then glued together to make larger panels from which small beams (nominally 10 x 10 x 150 mm3) were cut. After conditioning, the bending properties were measured. None of the flexibilized beams broke during testing and their stiffness was found to be less than 10% of the control beams.
This study investigates the potential of wood wastes, specifically post-consumer fiberboards, as a new source for cellulose nanocrystals (CNC). This underused resource has currently no commercially ...viable way to recycle it and so the volumes of fiberboard waste are growing rapidly. A sequential chemical fractionation was used to separate the three main constituents of wood, namely cellulose, hemicelluloses and lignin, and the non-wood components present in fiberboards, such as resins and finishes (e.g. varnishes, paints, plastics, laminates, etc.). Most of the non-cellulosic components and non-wood elements were removed by an alkali treatment followed by bleaching, resulting in a cellulosic fraction which is suitable for the further isolation of CNC by an acid hydrolysis step. The intermediate and final products were characterized by chemical composition, microscopic, spectroscopic and X-ray diffraction methods. The CNC obtained from wood waste are totally devoid of traces of contaminants and possess comparable characteristics and quality to those extracted from virgin wood fibers. The results indicate that fiberboard wastes can be used as promising alternative source for nanocelluloses production.
•Knowledge acquisition method of establishing optimization's objective functions.•Planning acquisition sessions through a decomposition of knowledge domain.•Rating sub-domains according to their ...importance and ease of acquisition.•Causal mapping of expert knowledge.•Multidisciplinary knowledge integration based on merging causal maps.
The design of wood-fiber based thermal insulating material with optimized properties and characteristics requires a good scientific knowledge of the latter. Currently, the technical, economic and ecological characteristics of a wood-fiber based composite mat are not well known. This article presents a methodology for the acquisition of expert knowledge so that the properties and characteristics can be modeled. The knowledge domain is multidisciplinary and it was delimited and decomposed into disciplines and domains of expertise. A panel of seven experts was constituted to cover the various disciplines and domains of expertise of the knowledge domain. Knowledge acquisition sessions, guided by the estimated importance and the availability of knowledge, were conducted using semi-structured interviews and the mapping of the existing causal relations between variables. A causal map was established to represent the causal knowledge of each of the experts and then, the established causal maps were assembled into a unique global causal map, which was subsequently validated by the experts. It contains the information necessary for formulating the properties and characteristics to be optimized, which were: thermal conductivity; thickness recovery of the material; the manufacturing cost and the product's environmental impact. Properties and characteristics are function of raw material type, their morphological properties and the manufacturing process variables. This methodology makes it possible to establish which objectives to optimize and which variables influence each objective. Consequently, the objective functions of the optimization problem can be clarified, specified and modeled.
The effect of sanding, as the last operation before finishing, on the quality of heat treated wood surfaces has been insufficiently explored and explained. This paper compared the effects of sanding ...with three commonly used sanding grit sizes P60, P100, and P150 on the surface roughness values of beech (Fagus sylvatica L.) wood. The wood samples were treated by the ThermoWood process at 200 °C for 2.5 h. A large range of standard roughness parameters (Ra, Rq, Rv, Rt, RSm, Rsk, Rk, Rpk, and Rvk) and two waviness parameters (Wa, and Wt) were included in the analysis, as well as environmental scanning electron microscope (ESEM) images of the sanded surfaces. The results showed that the heat treatment slightly increased the surface roughness and decreased the wood surface waviness after sanding. All roughness and waviness parameters increased with increasing sanding mean grit diameters by following a strong linear correlation. The processing roughness was closely approximated by the parameter Rk. For both, treated and untreated beech, sanding had a tendency to obscure (in magnitude and number) wood anatomical details in the measured data. However, the influence of wood anatomy in the valleys domain increased as the grit size became finer.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Wood recycling is common practice in most countries. Currently, recovered wood is used for relatively low value uses including energy generation, particleboard manufacture, animal beddings and ...landscape uses. This paper gives an overview of two research projects that aim to generate high-value products from recovered wood and thereby encourage even higher rates of wood recycling. One project is concerned with the extraction of nano-crystalline cellulose from waste MDF and the other produces laminated beams from recovered wood.
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