Search Results (20)

Osmia bicornis L. is a widespread and valued pollinator species. It is considered to be easy to breed, provided that the nesting material in which the bees build their nests is of sufficient quality and quantity. The aim of this study was to test several different types of nesting materials: reeds and commercial structures, including wood, MDF (Medium Density Fibreboard), plastic, paper or polystyrene. The highest levels of nest cavity occupancy were found in reeds (90%) and grooved MDF (over 80%). We have shown that maintaining mason bee colonies in polystyrene leads to reproductive losses (occupancy only 2% of nesting holes). Mason bees built the most cells in MDF (8.02 cells/hole) and wood (7.34 cells/hole), slightly fewer in plastic (6.83 cells/hole) and reeds (6.74 cells/hole), and the fewest in paper (3.67 cells/hole). The most cocoons per nest were obtained from reed (average 5.47), MDF (4.84) and plastic (4.74). We observed the highest mortality in plastic (2 larvae/hole), and the lowest in reeds (0.92 larvae/hole). In nests made of wood, MDF and paper, large nesting losses were caused by the migration of Ch. osmiae mites along and through the nest holes. The most hygienic nesting material turned out to be reed and plastic forms. Full article

Background: While low back pain (LBP) is the leading cause of disability worldwide, its clinical objective assessment is currently limited. Part of this syndrome arises from the abnormal sensorimotor control of back muscles, involving increased muscle fatigability (i.e., assessed with the Biering–Sorensen test) and abnormal muscle activation patterns (i.e., the flexion–extension test). Surface electromyography (sEMG) provides objective measures of muscle fatigue development (median frequency drop, MDF) and activation patterns (RMS amplitude change). This study therefore assessed the sensitivity and validity of a novel and flexible sEMG system (NSS) based on PEVA electrodes and potentially embeddable in textiles, as a tool for objective clinical LBP assessment. Methods: Twelve participants wearing NSS and a commercial laboratory sEMG system (CSS) performed two clinical tests used in LBP assessment (Biering–Sorensen and flexion–extension). Erector spinae muscle activity was recorded at T12-L1 and L4-L5. Results: NSS showed sensitivity to sEMG changes associated with fatigue development and muscle activations during flexion–extension movements (p < 0.05) that were similar to CSS (p > 0.05). Raw signals showed moderate cross-correlations (MDF: 0.60–0.68; RMS: 0.53–0.62). Adding conductive gel to the PEVA electrodes did not influence sEMG signal interpretation (p > 0.05). Conclusions: This novel sEMG system is promising for assessing electrophysiological indicators of LBP during clinical tests. Full article

Many fields of human activity benefit from the ability to create images of obscured objects placed behind walls and to map their displacement in a noninvasive way. Usually, imaging devices like Synthetic Aperture Radars (SARs) and Ground-Penetrating Radars (GPRs) use expensive dedicated electronics which results in prohibitive prices. This paper presents the experimental implementation and the results obtained from an imaging system capable of performing SAR imaging and interferometric displacement mapping of targets located behind walls, as well as 3D GPR imaging using a low-cost general-purpose radar sensor. The proposed solution uses for the RF section of the system a K-band microwave radar sensor module implementing Frequency-Modulated Continuous Wave (FMCW) operation. The low-cost sensor was originally intended for simple presence detection and ranging for domestic applications. The proposed system was tested in several scenarios and proved to operate as intended for a fraction of the cost of a commercial imaging device. In one scenario, it was able to detect and locate a 15 cm-diameter fire-extinguisher located at a distance of 3.5 m from the scanning system and 1.6 m behind a 3 cm-thick MDF (medium-density fiberboard) wall with cm-level accuracy. In a second test, the proposed system was used to perform interferometric displacement measurements, and it was capable of determining the displacement of a metal case with sub-millimeter accuracy. In a third experiment, the system was used to construct a 3D image of the inside of a wood table with cm-level resolution. Full article

This work presents a novel application of gas-diffusion microextraction (GDME) for the extraction and identification of volatile carbonyl compounds from a dry-process fibreboard (MDF) by combining high-performance liquid chromatography with diode array detection (HPLC–DAD) and mass spectrometry (MS). GDME is a simple, inexpensive, and environmentally friendly technique that allows the simultaneous extraction and derivatization with 2,4-dinitrophenylhydrazine (DNPH) of selected volatiles. The extraction conditions were optimized using design of experiments through a 2⁴ full fractional design followed by a Box–Behnken design, resulting in 35 min of extraction at 45 °C using 500 µL of DNPH 0.15%. The analysis of commercial MDF samples with different characteristics, such as thickness or colour, showed a distinct emission profile of volatile carbonyls. The principal emitting compounds found were formaldehyde, acetaldehyde, acetone, butanal, pentanal, hexanal, heptanal, octanal, and nonanal. A total of 25 compounds were identified using MS, including saturated and unsaturated aldehydes, ketones, dicarbonyls, and benzaldehyde-derivatives. This method can be a valuable tool for the qualitative evaluation of VOCs released from wood-based panels and for the assessment of indoor-air quality. Full article

This research work is focused on the development of an alternative method for manufacturing Wood Plastic Composite (WPC) panels based on Wood Veneers (WVs) and High-Density Polyethylene (HDPE) through compression molding, which enhances the physical properties, particularly, water absorption and moisture content. The aim of the present research was to develop alternative panels to replace commercial ones, which are heavily affected by hot, humid climates. In this context, the study began with the design process, which consisted of the collection and processing of primary material, production of the additional components necessary for the manufacturing process, determination of the WV ratio, and preparation of the samples. Thereafter, physical and mechanical tests were carried out on WPC, HDPE (control), commercial gypsum boards (GBs), plywood (PW), and medium density fiberboard (MDF) samples. The results indicate that the method applied to manufacture the WPC samples improved physical properties, achieving a water uptake of less than 4% in both proportions of replacement tested, in contrast to commercial panels, which reached values between 10% and 40%. In addition, a greater load capacity was achieved for lower thick elements. Full article

The wood-based panel industry generates a significant amount of solid residues in its production activities, including medium-density fiberboard (MDF) molding manufacturing. These residues consist of fine fibers measuring between 0.15 mm and 1.19 mm in length. A large proportion of them currently needs to be utilized, mainly due to the problem of excessive accumulation. They can be reused as raw material for manufacturing new products by adopting a circular economy approach. Their thermal properties can also be enhanced by impregnating them with phase change materials (PCMs). This research aims to develop a process for impregnating MDF panel residues (R) with PCMs to obtain shape-stabilized compounds capable of storing thermal energy. Three different commercially available PCMs were used. They were incorporated in the MDF residues by vacuum impregnation. The morphology, chemical structure, thermal stability, and phase change properties of the compounds obtained were studied by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectrometry, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), respectively. The SEM images indicated the PCM filled the empty spaces in the porous surface of the residue fibers to form shape-stabilized compounds. The FTIR spectrometry results indicated the compounds still exhibited characteristic peaks corresponding to both the MDF residues and the PCMs. No chemical reaction was observed between the two components. Moreover, according to the TGA results, the compounds produced exhibit high thermal stability. The R+PCM1 compound had the highest latent heat capacity of all the compounds developed in this study, reaching a maximum of 57.8 J⋅g⁻¹, and a phase change temperature comparable to that of PCM1. This better thermal performance could be attributed to the compounds having a higher encapsulation ratio (31.4%) than the other compounds developed. Furthermore, the R+PCM1 compound had an absorption capacity of 142.8%. This study, therefore, unveiled a promising alternative for storing thermal energy and valorizing solid MDF residues. Full article

The objective of this study was to investigate the gloss of different types of commercially manufactured varnish systems, including water-based (WB), polyurethane (PUR) and UV-cured (UV), applied on veneered MDF panels with sanded and thermally densified alder and birch wood veneers. The varnishes were applied at various numbers of layers on veneered panels. The gloss was measured at three angles of incident light: 20°, 60° and 85°. Statistical analysis showed that the type of varnish, the number of layers, the pre-treatment process, the wood species and direction of wood fibers significantly affect gloss of the coatings of veneered MDF panels. The type of varnish had a dominant effect on gloss. The highest gloss values were measured for the UV-varnished surface, and the lowest for WB- and PUR-varnished surfaces. Gloss was enhanced with an increase in the number of layers. Birch veneer provided higher gloss values compared to alder veneer. The gloss values measured along the wood fibers were higher than those measured across the fibers. No significant differences were found between the coatings created on sanded and thermally densified veneers for the average gloss values measured along the fibers at angles 60° and 85°. This study could have practical applications for producing value-added furniture elements using low-value wood species pre-treated by thermal compression. Full article

Machinability testing of ordinary wood-based panels can be useful, but testing prototypical (not produced industrially) panels is even more useful. So, the innovative (made only on a laboratory scale) flat-pressed WPCs were the subject of this study. The study consisted of experimental machinability testing of samples of fourteen different types of particleboards. Nine of them were innovative (non-commercial by design) particleboards, which differed from each other in terms of the type of plastic that was used and its percentage. The wood particles were bonded with either polyethylene (PE), polystyrene (PS) or polypropylene (PP). The percentages of plastic were either 30%, 50% or 70%. The research stand used for testing the machinability while drilling was based on a standard CNC (computerized numerical control) machining center. The experimental procedure involved the use of a specialized, accurate system for measuring cutting forces. Moreover, the maximum widths of the damage zones visible around the hole, on the drill entry side and the drill exit side were monitored using a digital camera and graphical software. Two key relative machinability indices were determined (quality problem index and cutting force problem index). Generally, the machinability of wood–polypropylene (W-PP) and wood–polystyrene (W-PS) composites was relatively good and generally similar both to each other and to the machinability of raw, standard particleboard P4. However, wood–polyethylene (W-PE) composite turned out to be the best wood-based board that was tested (even better than standard MDF) from the point of view of the cutting force criterion. On the other hand, the general quality of the holes made in W-PE composite was very poor (not much better than for raw, standard particleboard P5, but clearly better than for standard OSB). Full article

Fast growing Eucalyptus grandis W. Hill ex Maiden (EG), E. amplifolia Naudin (EA), Corymbia torelliana (F.Muell.) K.D.Hill & L.A.S.Johnson (CT), and Populus deltoides W.Bartram ex Marshall (PD) may be deployed in Short Rotation Woody Crop (SRWC) systems in the lower Southeastern USA, especially in Florida. To evaluate these species for possible use as medium density fiberboard (MDF) and other composites, 2.5 m logs of three EG clones, three PD clones, six EA progenies, four CT trees, and one P. tremuloides Michx. (PT) tree from northern Wisconsin as a control were characterized for basic wood properties before being chipped, pulped, and pressed into MDF. The chips were thermomechanically pulped (TMP) for a two-phase study of the factors expected to influence suitability for MDF production: wood characteristics, refining system, resin system, and MDF formation. Phase I used TMP and 4% phenol-formaldehyde (PF) resin to produce 17 MDF species/genotype batches (S/GB). Thickness Swell (TS), Water Absorption (WA), Internal Bonding (IB), Modulus of Elasticity (MOE), and Modulus of Rupture (MOR) were evaluated to: (1) assess within species and within tree variation, (2) relate basic wood properties to MDF potential, and (3) examine repeatability of MDF-making. There was considerable variation among and within species, but only minor within tree variation. Six of the seventeen S/GBs had superior physical and mechanical MDF properties. In Phase II, two of the six better performing Phase I S/GBs were evaluated, along with three average Phase I S/GBs. Phase II compared the effects on IB from using tube and drum blenders for resin application, the influence of using unscreened versus screened fibers, and the differences of using PF resin at 4% or 6% versus urea-formaldehyde (UF) resin at 8% or 12%. Overall, genetic variation among species, and particularly within these species, affected their potential for commercial MDF. Log specific gravity (SG), fines, MDF SG, and fiber length influenced MDF properties, as did refining and MDF-processing variables. Further study of specific processing requirements can optimize the potential of young EG, EA, PD, and CT genotypes for MDF and other composites. Full article

Eucalyptus amplifolia and Corymbia torelliana genetic improvement has been conducted in the lower southeastern USA by UF and collaborators since 1980. The collective accomplishments in genetic resources and potential commercial uses are summarized. For example, fast-growing, freeze-resilient E. amplifolia seeds are provided by 1st and 2nd generation seedling seed orchards (SSO) and a 2nd generation clonal seed orchard (CSO), while C. torelliana seed are available from 1st and 2nd generation SSOs. Breeding values (BV) have been developed for guiding the deployment of improved genotypes. Collaborative genetic improvement of these species is ongoing, including testing E. amplifolia in 11 countries and development of hybrid clones. Short Rotation Woody Crop (SRWC) systems may increase productivity and extend uses beyond conventional mulchwood to products such as medium density fiberboard (MDF), biochar, and energywood, while other possible applications include honey production, windbreaks, dendroremediation, and carbon sequestration. C. torelliana may be paired with E. grandis in two-row windbreaks to maximum windbreak effectiveness and may sequester as much carbon as E. grandis. Full article

WC-Co (tungsten carbide-cobalt) composites are widely used in industry, wear-resistant parts, and cutting tools. As successful tool materials, WC-Co carbides are widely applied in metal cutting, wear applications, chipless forming, stoneworking, wood, and plastic working. These materials are exposed to severe solid particle erosion by sand particles, such as in the wood industry. During the production of furniture with HDF (High Density Fibreboard), MDF (Medium Density Fibreboard), or OSB (Oriented Strand Board), there are observed problems with tool erosion. Contamination, mainly of the HDF by sand, is quite often, which is why all tools used for the machining of such materials are exposed to erosion by sand particles. Although many studies have been performed on the erosion of various metals, and erosion models exist to predict their erosion behavior, the issue is still relevant. The aim of the study was to determine the effect of grain size (submicron, ultrafine) and the manufacturing technology (SPS—Spark Plasma Sintering, conventional) used on the erosive properties of WC-Co sintered carbides. Sinters produced by the SPS method with different sizes of WC grains and commercial samples were used for the tests. Ten two-hour cycles were carried out under medium conditions of quartz sand and quartz sand with 10% SiC added. Used samples were characterised using scanning electron microscopy (SEM) and roughness was determined. Furthermore, erosion studies allowed individuating a wear mechanism as well as the possibility to foresee cutting performance in prospective application. Full article

Fe–doped titanium dioxide–carbonized medium–density fiberboard (Fe/TiO₂–cMDF) was evaluated for the photodegradation of methylene blue (MB) under a Blue (450 nm) light emitting diode (LED) module (6 W) and commercial LED (450 nm + 570 nm) bulbs (8 W, 12 W). Adsorption under daylight/dark conditions (three cycles each) and photodegradation (five cycles) were separately conducted. Photodegradation under Blue LED followed pseudo-second-order kinetics while photodegradation under commercial LED bulbs followed pseudo-first-order kinetics. Photodegradation rate constants were corrected by subtracting the adsorption rate constant except on the Blue LED experiment due to their difference in kinetics. For 8 W LED, the rate constants remained consistent at ~11.0 × 10⁻³/h. For 12 W LED, the rate constant for the first cycle was found to have the fastest photodegradation performance at 41.4 × 10⁻³/h. After the first cycle, the rate constants for the second to fifth cycle remained consistent at ~28.5 × 10⁻³/h. The energy supplied by Blue LED or commercial LEDs was sufficient for the bandgap energy requirement of Fe/TiO₂–cMDF at 2.60 eV. Consequently, Fe/TiO₂–cMDF was considered as a potential wood-based composite for the continuous treatment of dye wastewater under visible light. Full article

This paper presents the energy characteristics of wood and wood-based materials in the form of commercially available pellets, furniture board (MDF) and OSB. Toxicometric indices were determined for gaseous destructs arising from thermal decomposition and combustion of the materials studied. The paper proves that combustion conditions are crucial in terms of toxic destructive emissions. It has been shown that the combustion of wood-based materials under controlled conditions can lead to equally low emissions of toxic wastes as the combustion of traditional wood materials. The paper also presents the index of greenhouse gas emission, the so-called CO₂ equivalent, for the examined wood and wood-based materials. Full article

Brazil stands out internationally in the production and commercialization of wood products. Although the external and internal demand for these products is met by the Brazilian forestry sector, challenges related to the internal management of lignocellulosic waste are evident, as the country has structural difficulties in the sector of solid waste management. Therefore, the objective was to comparatively analyze the performance of the most abundant lignocellulosic materials in the Brazilian market, regarding energy recovery at the end of their life cycles. Pine wood treated with chromed copper arsenate (CCA), untreated pine wood, eucalypt wood treated with CCA, untreated eucalypt wood, uncoated medium density fiberboard panel (MDF), and MDF panel with melamine coating were sampled. The characterization included thermogravimetric analysis (TGA), scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDXA), and elementary analysis (EA). The presence of the CCA salts and the melamine coating reduced the energy potential of the biomass, altering the burning behavior and significantly increasing the amount of generated ashes. They also caused an increase in the concentrations of copper (Cu), chromium (Cr), arsenic (As), and cadmium (Cd) in the wood ashes as well as lead (Pb) and chromium in the panel ashes. Full article

Wood-based products usually have serious limitations concerning contact with water, both because wood is a hygroscopic material and because the commonly used binder has low moisture resistance. This paper studies the effect of panel moisture content (MC) on the physico-mechanical properties of medium density fiberboards (MDF). Several commercial MDF boards produced in Europe were stored at room temperature and relative humidity (RH) for 9 weeks (approx. range 15–20 °C and 50–85% RH). Every week, a strip of each MDF board was cut out, divided into 5 × 5 cm test pieces and its internal bond strength (IB) was measured. A strong influence of MDF moisture content on internal bond strength was observed and therefore IB test pieces were stored in a climatic chamber (either at 20 °C, 55% RH and at 20 °C, 70% RH). A decreasing linear relation was established between IB and MC. It was found that this effect is reversible: after drying, internal bond strength rises again (following a slight hysteresis). This work reinforces the importance of conditioned storage before board properties analysis, as described in European Standard EN 319. Full article