Search

Medium-density rigid polyurethane (PU) foams are often produced in sealed molds; therefore, the processes inside the mold and structure of the produced foam blocks need to be understood. The structural and mechanical anisotropy is shown to be the third variable along with (1) concentration of the nanoclay filler and (2) density, to determine the mechanical properties of the filled PU foam composites produced in a sealed mold. The varying anisotropy of the specimens hinders the accurate evaluation of the filling effect. The methodology for the estimation of the anisotropy characteristics of specimens from different locations within the nanoclay filled PU foam blocks is elaborated. A criterion, based on analysis of Poisson’s ratios, is formulated for the selection of specimens with similar anisotropy characteristics. The shear and bulk moduli are estimated theoretically, dependent on the filler’s concentration, using the experimentally determined constants.

Studies on the manufacture of medium density fiberboard (MDF) from oil palm frond (OPF) fibre were conducted to provide a sustainable and feasible source of lignocellulosic materials. The quality and properties of the fibre are very important as it dictates the final MDF properties. The properties of fibre like fibre pH, buffering capacity, and morphology can influence most of the MDF performances. Refining condition is one of the most important factors which determine the properties of the refined fibre. In this study, the effects of different refining pressures and temperatures on OPF fibre were evaluated. The refining of OPF fibre was observed at four levels of refining parameters; which were categorized as low (2 bar at 130 °C), medium (4 bar at 150 °C), high (6 bar at 170 °C), and severe (8 bar at 190 °C). The refining heating time of 5 minutes was employed. The pH, buffering capacity, morphology, and the surface of the fibres were evaluated. The refined fibres were used to manufacture fibreboard panels at a target density of 720 kg/m3 and 12% urea formaldehyde (UF) resin. The panel's physical (thickness swelling) and mechanical properties (bending and internal bonding strength) were then evaluated according to European Standard (EN 622-5, 2006). The results indicated that refining conditions affected the properties of the fibres and final boards. High steam pressure and temperature-induced pH changes in OPF fibres, leading to more acidic fibres and greater acid buffering capacity. The fibre separation was more adequate at this level and produced fibre with a smooth surface. Based on the test results for fibreboard properties, high steam pressure and temperature produced better dimensional stability of panels and bending and bonding strength. However, at the highest refining condition (severe level), the board performances began to deteriorate. The best performances of the samples were found for the panels made under refining conditions of 6 bar at 170 °C.

Globally, large cities are implementing guidelines to ensure that environment, economics and sociality are at the forefront of urban design. Promotion of healthier streets has created new opportunities for social and commercial interaction and more inclusive outcomes. However, while most megacity streets share commonalities, the streets in medium-density urban centres do not always share the same problems and opportunities. Following the London Healthy Street programme, interviews were conducted on four inner-suburban Wellington, Aotearoa-New Zealand streets. Findings highlight the impacts of changing demographics and street functionality and indicate that urban scale can be a factor in opportunity for innovative and user-friendly street design.

Medium-density housing (MDH) is posited as a solution to providing greater housing affordability. Yet, higher-density housing is often considered unsuitable for children. Our study investigates the...

This study aimed to identify the seroprevalence of chikungunya and its associated factors in the city of Quixada, Ceara, Brazil. We also aimed to identify the spatial distribution patterns of positive cases. A cross-sectional survey was conducted with a questionnaire about clinical symptoms, socioeconomic and demographic factors, and a 10 ml blood sample was collected and analysed by ELISA. For the bivariate analysis, we use the chi-square test, a prevalence ratio and its 95% confidence interval. A robust Poisson hierarchical regression was used to adjust for confounders. The Kernel density was performed for the spatial analysis. A total of 409 samples were analysed; of them, 70.7% were seropositive for previous exposure to chikungunya virus (CHIKV). High seropositivity for CHIKV was higher in female participants (75.5%; PR = 1.23; 95% CI: 1.06-1.43), those aged 31 years or more (74.3%; PR = 1.62; 95% CI: 1.04-2.52), and those with elementary education level (75.0%; PR = 1.30; 95% CI: 1.06-1.60). There were also high seroprevalence in those with less than a minimum wage per month (89.5%; PR = 1.59; 95% CI: 1.11-2.30), housewives (87.5%; PR = 1.64; 95% CI: 1.24-2.18) and unemployed (80.0%; PR = 1.50; 95% CI: 1.10-2.06). After adjusting for age, morning stiffness was the only chikungunya symptom that remained associated (PR = 1.20; 95% CI: 1.06-1.37; p < .001). There was an area of high density of cases in the downtown and two areas of medium density in nearby regions. Otherwise, the higher seroprevalence rates were in the peripherical neighbourhoods. There is a hyperendemicity of CHIKV in Quixada, and most cases are spatially contiguous. The main associated clinical sign is morning stiffness, but other factors such as low income and spending a longer time at home were significantly associated with higher seroprevalence.

Medium density fibreboards (MDF) are currently not recycled after service life, but various publications report on recycling by the disintegration of MDF using various techniques and the properties of obtained recovered fibres (RF). In this study, the main aim was to put back RF into the MDF manufacturing process as closed-loop recycling using repeated thermo-hydrolytic disintegration. Compared to previous studies, the focus was on the recycling of MDF with a relatively low F:U molar ratio (1.11). Urea–formaldehyde-bonded MDF with a target density of 700 kg m−3 was subjected to thermo-hydrolytic disintegration in an autoclave using only water at 95 °C for 20–30 min. Afterwards, the properties of RF and virgin fibres (VF), of MDF produced thereof and the composition of the disintegration water (DW) were determined. The nitrogen content (NC) revealed that RF contained about 30% of the initially applied UF. The pH of the DW hardly changed during recycling and it contained considerable amounts of reducing sugars. Using RF did not result in higher formaldehyde emissions than VF. Compared to earlier studies using a higher formaldehyde content (higher F:U ratio), MDF bonded with modern UF resins can be disintegrated under clearly milder disintegration conditions with respect to temperature and time. The properties of recycled MDF were similar to those of reference MDF; up to 100% RF could be used without severely deteriorating the strength and increasing formaldehyde emissions from these panels.

The demographic history of Creole cattle in Argentina and in Latin America dates back to the time of the Spanishcolonization. This study aimed to investigate the potential use of a medium­density SNP array to describe cattlefromthe most representative andoldest herds of the Argentine Creole cattle breedregisteredat the time of theconstitution of the Argentinean Creole Cattle Breeders Association and to explore the phylogenetic relationship withCreole cattle fromother LatinAmericancountries. Toachieve this goal, genotypes from51 animals on34,008autosomal SNP were used to generate genetic distance matrices based on the proportion of shared identical­by­statealleles among individual animals and animals clustered according to their origin, analyzed by the PLINKprogram.Aneighbor­joining phylogenetic tree based on pairwise genetic distance was constructed using PHYLIP and wasprepared for visualization using FigTree. Amultidimensional scaling analysis was performed to evaluate the levelof relationship in terms of genetic distance among the different animal clusters. Genetic distances between animalsvaried from0.186 to 0.357 when considering all pairs of animals, and from0.186 to 0.338 when considering Creolepairs. The dendrogramobtained showed three major clusters. Cluster 1 included Latin American Creole cattle fromColombia, Guadalupe, Paraguay, and Uruguay, and the reference groups of Holstein and Jersey cattle. Cluster 2contained exclusively Patagonian Creole cattle, while the third cluster included the remaining Argentinean Creoles.The genetic relationship patterns obtainedvia multidimensional scaling showeda close relationship among fourgroups of Creole animals fromArgentina. The closeness between clusters can be explained in part on the basis ofearly migration of animals that gave rise to founders herds at some Argentinean locations. The outcomes of thisstudycontribute toabetter understandingof the compositionof the earlyfounder herds of Creole cattle inArgentina and the relationship with other Latin America Creole cattle populations.

Aim of this study was to evaluate the effect of aluminium hydroxide and borates, separately or combined with ammonium polyphosphate (APP), upon the technological and fire properties of medium density fibreboard (MDF). Fire resistant MDF was fabricated in the laboratory from Scots pine (Pinus sylvestris L.) fibres bonded with a high molar ratio melamine-urea-formaldehyde resin. Overall, 24 h-swelling and water absorption properties of the treated boards were improved or remained unchanged compared to untreated ones. On the contrary, the internal bond strength (IB) of the fibreboards was significantly reduced up to 48%. The fire properties of the fibreboards were assessed by the determination of limiting oxygen index and cone calorimetry. As expected, the tested fire-retardants improved the fire resistance of the boards. Furthermore, the combination of aluminium hydroxide with ammonium polyphosphate considerably upgraded the fire retardancy while the incorporation of borates into APP showed much weaker effects.

Pile driving in low- to medium-density chalk is subject to significant uncertainty. Predictions of “chalk resistance to driving” (CRD) often vary considerably from field driving behaviour, with both pile refusals and free falls under zero load being reported. However, recent field studies have led to better understanding of the processes that control the wide range of behaviour seen in the field. This paper describes the primary outcomes of the analysis of dynamic tests at an onshore and an offshore site and uses the results to propose a new method to predict CRD. The method is based on phenomena identified experimentally: the relationship between cone penetration resistance and CRD, the attenuation of local stresses as driving advances, and the operational effective stress interface shear failure characteristics. The proposed method is evaluated through back-analyses of driving records from independent pile installation cases that were not included in developing the method, but involved known ground conditions, hammer characteristics, and applied energies. The proposed method is shown to lead to more reliable predictions of CRD than the approaches currently applied by industry.

Bare patches in alpine meadow are the main manifestation of its degradation. The change of bare patches in an alpine meadow in the Yellow River Source Zone during 2018–2019 was studied in relation to the disturbances caused by plateau pika (Ochotona curzoniae) population and simulated grazing via artificial mowing both independently and interactively. The disturbance was set at three levels of high, medium and no disturbance (control group). Bare patches were mapped by from unmanned aerial vehicle (UAV) images with fine resolution of 1 cm obtained in August 2018 and August 2019 in ArcGIS. The results showed that the total area of bare patches decreased by 112.05 m2 in sub-plots devoid of pika disturbance but increased by 126.37 m2 in other sub-plots. The highest rate of increase is 89.02%. The individual effect of pika exceeds the joint effect of pika and mowing disturbances. The sole effect of mowing is lower than the joint effect of pika disturbance and intensive mowing, but higher than the joint influence of pika disturbance and moderate mowing. Strong pika disturbance (14 per sub-plot) caused the influence of mowing from moderate to intensive to increase by five-fold. The area of bare patches treated with moderate mowing and no pika disturbance decreased at the highest pace (−37.22%). Intensive mowing and medium density pikas (100 pikas/ha) are considered the thresholds at which the bare patches start to expand. Even if the meadow is mowed at the medium and high intensity, the area of bare patches can be significantly reduced if plateau pika population is controlled to a low level. ANOVA analysis and long-term macro-scale satellite-derived results reveal that pika disturbance is more important in causing the bare patches to change than simulated grazing. Therefore, it is more important to control the number of pikas than to reduce grazing intensity to prevent the expansion of bare patches in the degraded alpine meadow in the study area.

This paper reports an in-depth comparative study on the effects of Trametes versicolor on sugar-cane residue polypropylene composite and medium density fibre board. The samples were subjected to th...

Urban parks are public recreational facilities that can provide many benefits, reducing stress from fatigue. However, some urban parks are not frequently visited because it feels very dark inside so that many parks are unkempt and empty of visitors. This study aims to determine how the comparison of park visitors' perceptions at different levels of closure based on the sense of security and restoration they received. This research is experimental in nature, so respondents are asked to rate several edited photos to determine the optimal combination of closure. Data was collected by distributing questionnaires online for two weeks (N = 272). Furthermore, the data were processed through the ANOVA test to see which combination of enclosure was rated the highest and the lowest based on perceived savety and restoration. The results show that visitors’ perceived safety can be achieved by applying a combination of closeness 8 (high density, far position, medium scale (6 meters)) and 9 (medium density, close position, high scale (9 meters)), while visitors’ perceived restoration tends to the same and not tied to different combinations of closure. The implementation of this study is how to design the tree enclosure in urban parks to increase the participation of residents visiting the park. Urban parks that are frequently visited will be sustainable in future, so maintaining parks can be started from designing enclosure of parks.

Annotation. Gauze remains the main dressing. It is used to make swabs for drying wounds and dissecting tissues. The purpose of the work is to establish the optimal density of the swab for drainage of the wound and preparation of tissues. Swabs made of 10x12 cm gauze fragments were investigated. The gauze fragments were weighed before and after immersion in water and the absorption capacity per unit dry weight was calculated. The dissecting properties of the swabs were investigated on plasticine blocks, the surface of which was pressed with a force of 12 N. The formed depressions were filled with gypsum. The volume and weight of the casts were determined. To determine the reliability of the difference between the two mean values used the reliability criterion t (Student’s test). It was found that loose swabs absorbed 913.5±43.9% of water, medium density – 766.3±55.2%, dense – 682.9±70.1 (p˂0.05). This is due to the fact that loose swabs have the largest in radius and length of the capillaries. When studying the recesses formed by embossing the swab on the surface of the block, it was found that when using loose swabs formed a deep conical recess, which indicated the risk of injury. When embossed with dry swabs of medium density received molds weighing 0.034±0.0000011 g, wet – 0.033±0.0000011 g (p>0.05). When using dense swabs – 0.037±0.0000011 g and 0.034±0.0000011 g, respectively (p˂0.05). Dense swabs showed the best dissecting properties. When wet, they are slightly but significantly reduced. Medium density swabs have slightly worse dissecting properties. When wet, they did not change significantly. We attribute the decrease in dissecting properties to the displacement of water from the gauze when pressed. Thus, loose swabs (∆M=913.5%±43.9%) absorb fluid best, which determines their predominant use for wound drying. Dense swabs are characterized by the lowest absorption capacity (682.9±70.1%), the best dissecting properties.

The manufacture of fabrics and textiles is one of the industries that has witnessed a great development in recent times in the whole world significantly, which has led to the production of many types of fabrics and textiles with special characteristics such as Waterproof. This type of waterproof fabrics has become one of the most important fabrics widely used in the field of ready-made garments, especially for the production of winter jackets, which are known commercially as (pump jackets), which are used by various categories and ages, women, men and children. This is due to its distinctive appearance properties in addition to its ability to prevent water penetration with the ability to ventilate the body by allowing the absorption of sweat and the exit of water vapor. This type of fabric is usually coated with a waterproofing material such as rubber, polyvinyl chloride (PVC), polyurethane (PU), acetyl silicone, fluoropolymers and waxes, so it requires a high technical level in dealing with it, during its production stages or during its decoration with various decorative methods. Machine embroidery is one of the most appropriate decorative methods used to add a distinctive decorative character to these fabrics, making them richer, but some technical defects of that process may appear, which directly affects the appearance of the cloth and distorts its surface due to its special nature, hence the idea of Research to study the effect of machine embroidery variables on the appearance of waterproof fabrics as an attempt to set standardized standards for embroidery. The research problem can be summarized in the following questions: 1- What are the natural and mechanical properties of waterproof fabrics? 2- What is the effect of the difference in the density of the machine embroidery stitches on the appearance of the waterproof fabrics? 3- What is the effect of the difference in the type of yarn used in machine embroidery on the appearance of waterproof fabrics? 4- What is the effect of the strengthening methods used in machine embroidery on the appearance of waterproof fabrics? 5- Access to the best technologies for dealing with waterproof fabrics. Research objectives: 1- Determine the natural and mechanical properties of waterproof fabrics. 2- Determine the effect of the difference in the density level of the machine embroidery stitches on the appearance of waterproof fabrics. 3- Determine the effect of the difference in the type of machine embroidery yarn on the appearance of waterproof fabrics. 4- Determine the effect of strengthening ways on the appearance of waterproof fabrics. 5- Determining the best techniques for automatic embroidery on waterproof fabrics, which achieve the highest appearance. Research Significance: The results of this study are useful in overcoming the technical defects that occur during machine embroidery on waterproof fabrics. And identifying the aspects and limitations in it, which may result from the wrong choice (for the level of stitch density - the type of embroidery yarn - strengthening ways). This keeps preserving the aesthetics of the fabric and the appearance of the embroidery on it. Methodology: The current research follows the experimental approach to suitability to achieve the research objectives. Results ; By studying the effect of the machine embroidery variables (stitch type - stitch density - embroidery yarn type - strengthening methods) on the appearance of embroidery on waterproof fabrics, it was found that: -- The best effect of the stitches and densities of machine embroidery on the appearance of the embroidery on waterproof fabrics is the Counter stitch with medium density (1.50), followed by the Run stitch with high density (0.80), and finally the Satin stitch with low density (0.85). - The best types of machine embroidery yarns for the appearance of embroidery on waterproof fabrics is silk thread, followed by polyester thread, then metallic thread. - The best strengthening methods when embroidering on waterproof fabrics are strength with paper with non-stick wadding, followed by strength with non-stick wadding, and finally strength with paper.

A treatment of dose nonuniformity inside Lo Ren and purple star apples irradiated by 10 MeV electron beam accelerator has been proposed by using medium density fiberboards (MDF). The dose uniformity ratios (DURs) inside the Lo Ren and purple star apples were estimated as 2.47–2.48 and 2.18–2.22, respectively. To reduce the DURs, the arrangement and the thickness of the MDF boards were determined by Monte Carlo simulations. Measurements of the absorbed doses have been conducted to compare with the simulations. The DURs were reduced to 1.36–1.39 and 1.44–1.46 for the Lo Ren and purple star apples, respectively.

Some Amazon timber species, such as Cedrela odorata and Swietenia macrophylla, are considered vulnerable due to overexploitation. Cedrelinga cateniformis, known as false cedar, has a medium-density wood that may replace species under great commercial pressure. We have assessed some physical (basic and apparent density; tangential, radial, and volumetric shrinkage) and mechanical properties (resistance to parallel compression, shear, static bending, and static bending stiffness), as well as the shear strength in the bonding surface. With an average apparent density of 0.721 g/cm³, the C. cateniformis wood presented density and shrinkage classified as medium and anisotropy coefficient of 1,654. The mechanical properties were similar or superior to higher density woods. C. cateniformis fits the C20 resistance class, with the potential to substitute species such as Couratari oblongifolia, Vochysia maxima, Cedrela odorata, and Swietenia macrophylla. The shear strength in the bonding surface was lower than that of solid wood and the wood failure percentage was below the recommended. However, the results indicate that it is possible to find an efficient bond when evaluating different bond pressures. C. cateniformis have also a high potential for timber plantations, due to its ecological characteristics, for instance, resistance against the Meliacea shoot borer and association with mycorrhiza.

The extent of linkage disequilibrium (LD) at genome wide level is crucial in determining the effectiveness of genomics tools in livestock breeding. The present population genomic study was conducted in native goat breeds of Kerala namely; Attapady Black goats (n=24) and Malabari goats (n=24) to characterise extent of LD within 40kbp marker interval using genome wide single nucleotide polymorphism (SNP) marker data obtained by SNP50 BeadChip genotyping. Extent of LD between bi allelic markers was measured using correlation coefficient (r2). Mean r2 between adjacent SNP pairs across all autosomes within 40Kbp marker interval was low (Attapady Black: 0.1336; Malabari: 0.1284). The LD varied across autosomes in native goats. It was the highest for SNP pairs on Capra hircus autosome 6 (CHI 6) and the lowest for SNP pairs harboured in CHI 28 in Attapady Black goats and for SNP pairs in CHI 29 in Malabari goats. The low LD estimates indicate the genetically diverse nature of native goats. Current results also imply that denser SNP beadchip array with inter marker interval of below 40kbp would be desirable for effective genome wide association study (GWAS) and genomic selection in native goats.

Volatile organic compounds (VOCs) emitting from building materials are one of the main sources of indoor pollution. Environmental factors have obvious effects on VOC emissions from building materials. However, no unified conclusions have been achieved on the influence of relative humidity (RH) and air change rate (ACR), and there is little research on the correlations of RH and ACR with parameters in VOCs emission fitting models. Therefore, factor analysis was applied in this paper to study the influence of RH and ACR on VOCs emissions. Medium density fibreboard pannels with the coating of oil-based paint were applied at four ACR (0.5 h−1, 1.0 h−1, 2.0 h−1, 3.0 h−1) and four RH (20%, 30%, 50%, 70%) conditions in 60 L environmental chambers. Tenax TA tubes were used to collect VOCs and thermal desorption-gas chromatography mass spectrometry was applied to determine the concentrations. The results show that RH influences the initial stage of VOCs emission and has a positive correlation with the emission concentrations. In the later emission stage, RH has no obvious influence on VOCs emissions, while the concentrations of VOCs are inversely proportional to ACR. The parameters in the single exponential model a1 and b1 have power-law or polynomial relationships with ACR and RH. ACR has negative correlations with a1 and positive correlations with b1, resulting in a negative influence on VOCs emissions, while RH has a complex influence on VOCs emissions. This study elucidated how RH and ACR impact VOCs emissions from oil-based paint coating medium density fibreboard and further influence human health exposure risks, which can then be used to improve indoor air quality.

Empty Fruit Bunches (EFB) are abundance residues from palm oil plantation was recognised as a potential material for manufacture such as particleboard and medium density fibreboard (MDF). The objective of this study is to identify and assess the potential effects of chemical treatment and concentration on the mechanical and bonding properties of MDF from EFB oil palm fibres. The EFB fibres were treated at 0.2, 0.4, 0.6 and 0.8% of sodium hydroxide (NaOH) and acetic acid (CH?COOH), and the fibres were used in the MDF production. Mechanical test included modulus of rupture (MOR), modulus of elasticity (MOE) and internal bonding (IB) were conducted. Between the chemical treatment and the concentration, the chemical types used had a more prominent effect compared to the concentration. This study also shows that both treatments resulted in different MDF performance, where acid acetic fibre produced better bending and bonding properties. The optimum condition was 0.4% for NaOH and 0.6% for CH?COOH to produced panels with good strength and better dimensional stability. Such sample for 0.4% NaOH had 17.9 MPa, 1297 MPa and 0.48 MPa, and for 0.6% CH?COOH had 22.1 MPa, 1641 MPa and 0.56 MPa, for MOR, MOE and IB, respectively.

Australian cities rarely meet their targets for infill development and experience a ‘missing middle’ in terms of urban density. This paper surveys the barriers to medium-density projects on infill ...

Pinus pinea(stone pine) is an important species for its delicious seeds -the pine nuts-, the most expensive dry fruit worldwide. In native habitats, planting density is a key silvicultural tool in this highly heliophile species due to its impact on growth and cone yield. In Chile, the densities of adult plantations are medium and high. The goal of this study was to assess the impact of density on growth and cone yield in established plantations. Thirty plantations, 15 at high density (1,667 trees ha-1) and 15 at medium density (500 trees ha-1), were matched into 15 pairs of similar plantations regarding age and site characteristics. Planting density had a significant impact onP. pineagrowth and cone yield. The medium density was associated with 46 % higher diameter-at-breast-height (DBH) and 2.8 times higher cone yield than those presented by a high-density plantation scheme. However, at 500 trees ha-1, average tree height might turn cone harvesting difficult and expensive. In humid areas (Chilean South macrozone), the medium planting density had a more important effect on cone yield than on growth. Our study confirms previous research in stone pine native habitats and highlights the need to find an optimum planting density to favor cone yield and harvest., El pino piñonero (Pinus pinea) es una especie importante por sus deliciosas semillas (piñones), el fruto seco más caro del mundo. En su hábitat nativo, la densidad de plantación es una decisión silvicultural clave en esta especie heliófila debido a su impacto en el crecimiento y producción de piñas. En Chile, las densidades de plantaciones adultas son medias y altas. El objetivo de este estudio fue evaluar el impacto de la densidad en el crecimiento y producción de piñas en plantaciones establecidas. Treinta plantaciones, 15 con alta densidad (1.667 árboles ha-1) y 15 con densidad media (500 árboles ha-1) se agruparon en pares de plantaciones de similar edad y características del sitio. La densidad de plantación tuvo un impacto significativo en el crecimiento y producción de piñas deP. pinea. La densidad media estuvo asociada con 46 % mayor diámetro a la altura del pecho y 2,8 veces mayor producción de piñas que en el esquema de alta densidad. No obstante, en la densidad de 500 árboles ha-1, la altura media puede dificultar y encarecer la cosecha de piñas. En áreas húmedas (macrozona sur de Chile), la densidad media de plantación tuvo un efecto mayor en la producción de piñas que en el crecimiento. Este estudio confirma investigaciones previas realizadas en hábitats nativos del pino piñonero y subraya la necesidad de encontrar una densidad de plantación óptima para favorecer la producción de piñas y la cosecha.

The aim of this study was to investigate the effect of blade type and sharpness angle on blade wear, cutting power, and surface roughness. The study was conducted on medium-density fibreboard (MDF) panels. Two blade types were analyzed (high-speed steel and cemented carbides) along with three variants of sharpness angles (40°, 45°, and 55°). Machining operations were performed on a spindle moulder at a feed rate of 6.3 m/min and rotational speed of 4500 min-1. The blade wear criterion was adopted as the loss of cutter surface area measured on the rake face. Roughness was determined using the Ra parameter, which was measured at three points on the cross-section of the MDF panel. A new, multifaceted approach to the study of cutting a narrow surface of the MDF board was used, thanks to which the interaction of such parameters as blade wear, cutting power, and machining quality as well as the type of material of the knives and their angular parameters were determined. An increase in blade wear and cutting power was recorded with an increase in cutting path, while roughness at the MDF panel cross-section varied. The cemented carbides cutter with the 45° angle may be proposed as optimal, because it showed a relatively low wear and cutting power while providing good quality of the milled surface.

Land supply for new housing in the established middle-suburbs (greyfields), where much urban infill potential exists, is “locked up” due to restrictive land-use regulation. As a result, most reside...

The paper presents the results of studies of the important physicochemical and technological parameters of the CCR-2 composite highly filled polymer chemical reagent, consisting of Na-CMC, alumac, soda ash and caustic soda and waste from the production of chemical fertilizers, as well as drilling fluids based on it. The compositions and physicochemical properties of the waste-slag of the chemical plant of Farg'onaazot JSC, which increases the density and water index of drilling fluids, were studied in detail. The optimal compositions of composite polymer chemical reagents of CCR-2 class using waste-slag from chemical production of fertilizers have been developed. The physicochemical and technological characteristics of the developed composite highly filled polymer chemical reagents KHR-2 (from KHR-2-1 to KHR-2-5) and 10% low and medium density drilling fluids based on them are given.

This work provides a study about the incorporation of a high density polyethylene (HDPE) matrix composite in medium density fiberboards (MDF). A composite was processed in a single screw extruder with 5% of Pinus spp fibers in a HDPE matrix and applied as reinforcing agent in MDFs, as well as pure HDPE, in 11 different variations, using 12% of urea-formaldehyde resin and nominal density of 750 kg.m−3. The composite and the pure HDPE were analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The DSC results showed that both polymeric matrix and composite presented the same melting temperature but the composite had a reduced melting enthalpy and crystallinity due to thermal history. SEM analysis showed a well distribution of fibers on the composite. The results of technological properties of MDFs were compared to commercial MDF standards. The MDF reinforced with 40% of polymeric composite reached all minimum standard requirements, being the most recommended to be used as an alternative to conventional MDF, in terms of physical and mechanical performance.

Consistent exposure to elevated sound levels results in noise health effects. The industrial environment represents a major source of such effects. There is significant variation in noise at different sections of such industries due to which most of the workers are exposed to these sounds at one or another level. In this study, a noise level measuring methodology is used for fixed and moving workers. This article introduces an algorithm for optimum selection of earmuff and earplug for different working places depending upon the exposure to noise. Medium density fiber industry is considered as a case for this study. It considers workers who are busy at a single point and face a consistent amount of noise as well as the workers who move and are exposed to a varying level of the noise. Noise level meters are used to measure the noise level at different points. At each point, the average value of the samples is taken. Based on the data collected, earmuff with high noise reduction rate is assigned to the workers closed to the machines. Implementation of the developed algorithm reduced the effect of noise on workers by 6.9%, 5%, and 16.3% for the chipper machine, pneumatic fan, and sanding machine, respectively, that were identified as the major source of noise at medium density fiber industry. This percentage reduction helped the workers to bring them to the optimum safe level of noise that is 85 dB and protect them from hearing loss severity due to frequency variations.

The paper investigates the addition of Nano-Al2O3 powder (alumina, Average Particle Size: 20 nm) on the characteristics of the Medium Density Fibreboards (MDF) made by the forest fibers. Some impor...

Purpose: To determine whether foam density affects modified Romberg balance test performance. Materials and Methods: Controls and patients with vestibular disorders performed Romberg tests on medium and medium firm foam, with their eyes closed and the head still and moving in yaw and pitch. The trial duration and number of head movements were measured. Results: Subjects aged >60 years performed longer and with more head movements on medium firm foam than on medium foam. Older controls did not differ between medium firm and medium foam. Older patients had higher scores on head-still and head-yaw trials on medium firm foam versus medium foam but pitch trials did not differ. Females, controls, and patients had longer trial durations and more head movements on medium firm foam than on medium density foam; male controls did not differ by foam density. Male patients differed in yaw trials. Conclusion: Foam density affects scores. Clinical decision-making may be adversely affected if the clinician uses foam of a density that is not the same as that of the foam that was used in the studies that developed descriptive statistics, sensitivity, and specificity.

The aim of the present article was to analyse the adhesive joints of different types of the furniture boards used for the furniture production. The present article included a comparative analysis of the adhesive joints of the particle board and the medium-density fireboard (MDF) pressed with the following types of film: A 0.3 mm thick PVC film and a 0.8 mm thick acrylic film, made with use of a single-component reac-tive hot-melt adhesive based on the PUR 706.2 ME polyurethane. It was observed that, among others, the adhesive joints made of the particle board with a pressed 0.3 mm thick PVC film and the adhesive’s basis weight of 24 g/m2 is characterised by better strength properties than the adhesive joints of the particle board with the adhesive’s basis weight of 48 g/m2.

In this study, wood density, anatomical characteristics, and major chemical components were investigated on branchwood, trunkwood, and rootwood of three Alnus sibirica trees grown in Maoershan Mountain, Northeast China. The anatomical structure and composition of xylem within a tree were spatially heterogeneous. At the alpha = 0.05 level, the differences among branchwood, rootwood, and trunkwood were significant in wood density, cell dimensions, extractives, and ash content. The trunkwood was desired as papermaking raw material and structural timber because of its high-quality fibers, cellulose content, and medium density value. Because of its similar density to trunkwood, large-sized branchwood could be used as a substitute for structural materials. The rootwood with low densities and large vessel dimensions was suitable for producing short fiber biocomposite.

Medium density fibreboard (MDF) is extensively used in the construction and furniture industry, especially as building materials, household furniture, fencing and flooring because of its desirable properties such as being low cost, having excellent mechanical and physical properties and being isotropic. However, the sustainability of wood supply has become a serious environmental issue. Therefore, it is necessary to find alternative strategies in order to reduce the wood demand for producing wood-based composites such as MDF. This article reviews the various alternative materials such as wheat straw, kenaf, corn stalk, sisal and bagasse to reduce the dependency on wood in the related industries. Moreover, this article also reports on the development of environmental friendly adhesives and non-adhesive MDF to reduce the emission of formaldehyde which is a carcinogen agent and may lead to various health problems.

In the near past, industrial hemp (Cannabis sativa L. subsp. sativa) found main application in the production of ropes and fabrics. At the present moment, this crop finds increasingly big application for pharmaceutical purposes and in the cosmetics industry. As a result of which not only hurds, but whole stalks remain as waste from this production. On the other hand, MDF, which on a world scale are the second production of wood-based boards in terms of volume after that of veneer plywood, allow at least partial inclusion of non-woody lignocellulosic raw materials in their composition. That is why, in this paper, an investigation about the possibility for inclusion of mass of hemp stalks in the MDF composition is presented. Under laboratory conditions, previously washed hemp stalks were defibred. The defibration was performed in a laboratory crusher defibrator for 2 min. Under laboratory conditions, MDF with participation of mass of hemp stalks form 0% to 100% in the MDF composition were produced. The content of mass of hemp stalks was increased by a step of 10%. The boards were produced at a temperature of hot pressing of 185 °C, with 10% participation of urea-formaldehyde resin (UFR) and have a density of 850 kg/m3. The effect of the content of mass of hemp stalks on the physicomechanical indicators of MDF was established. Regression equations for this effect on the individual physicomechanical indicators were also derived. It has been established in case of increase of what share in the composition of boards, most significant deterioration of the MDF indicators is observed. On this basis, a recommendation for the maximum justified content of mass of hemp stalks in the MDF composition was derived.

In this study, the effects of vermiculite of volcanic minerals usage on the surface properties were investigated in medium density fiberboard (MDF) production. The test boards were produced using the dry method with 12% urea formaldehyde resin. Additions of 10%, 15%, 20% and 30% vermiculite were used based on the full dry fiber weight. Surface roughness, color and gloss values of both surfaces of the obtained boards were determined. Based on the results, the ratio of vermiculite increased, roughness values on the surfaces increased. The roughness values in the bottom surface of the produced boards were determined to be higher than the top surface. With the use of 30% vermiculite, the average minimum surface roughness (Ra) was found to be 8.65 μm on the upper surfaces and 15.44 μm on the lower surfaces. It has been found that total color change and brightness are improved by the increase of vermiculite usage and the color change on the bottom surface is found higher. In short, the use of vermiculite in the production of MDF negatively affects the surface roughness and discoloration of the boards, but it has been found to positively affect the gloss