BioResources (E-Journal)
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Mismatch between Classroom Furniture and Anthropometric Measures in Children Aged 3 to 6 Years: Case Study of the South-West Region of Kosovo
No full textAppropriate seating environments and comfort during educational activities at worktables are prerequisites for educational institutions in general. In this regard, special attention should be given to children enrolling in early childhood and kindergarten education within the pertinent institutions. Many researchers have concluded that a bad posture among children can be indicative of health problems and stagnation in the education process. The main purpose of this study is to determine whether the chairs and tables are suitable ergonomically for children aged 3 to 6. Also, in the study, the dimensions of children were analyzed and calculated to design ergonomic chairs and tables for this age group. The research was carried out within early childhood and kindergarten institutions in the southwest region of the Republic of Kosovo. Measurements were taken of 210 children in public and private institutions. According to (ISO 7250-1: 2017), field measurements include 12 body parts needed to determine furniture dimensions. The study's findings indicate a significant mismatch between anthropometric measurements and the dimensions of furniture across all the institutions examined
Influencing Factors of Double Roll Coating Ratio of Reconstituted Tobacco by Papermaking
No full textTo investigate and elucidate the influencing factors and laws of double-roll coating ratio (CR) for papermaking reconstituted tobacco and to assess the effectiveness of CR in characterizing the finished product's hot water soluble (HWS) content, base sheet (BS) specimens of reconstituted tobacco with varying bone-dry basis weights and moisture contents were prepared. These sheets were then coated with different physical indices of coating liquids using a small double-roll coater at different sheet speeds. Subsequently, the CR and HWS content of the finished product were analyzed. The results showed that when the viscosity of the coating liquid was > 280 mPa·s, the moisture content of the BS should be maintained between 18% and 22%, and the speed of the BS should be > 120 m/min; when the viscosity of the coating liquid is < 280 mPa·s, the moisture content of the BS should be maintained between 14% and 18%, and the speed of the BS should be > 120 m/min, so that higher HWS can be obtained in finished products. The bone-dry basis weight of the BS should be kept between 40 and 60 g/m2. The suspension solid content of coating liquid should be < 9.5%
Mechanical and Degradation Properties of Degradable Cover Materials for Sugarcane Leaves
No full textMulch was prepared using composted sugarcane leaves, with polyvinyl alcohol and cationic starch as adhesives, through compression molding. The study aimed to investigate the effects of different adhesives on the mechanical properties, thermal oxidative degradation performance, and biodegradability of the covering materials. The results indicated that, when the adhesive dosage was consistent, cover material A, which utilized polyvinyl alcohol as the adhesive, exhibited higher tensile strength and elongation at break compared to cover material B, which employed a blend of polyvinyl alcohol and cationic starch. Specifically, at an adhesive dosage of 20%, cover material A achieved a tensile strength of 0.46 MPa and an elongation at break of 7.72%, representing the highest values among all experimental groups. There was minimal disparity in the thermal oxidative degradation performance between materials prepared with either adhesive; however, a higher quantity of adhesive led to decreased biodegradability performance. After being buried in soil for 120 days, the degradation exceeded 40% for both materials, resulting in loss of their original shape and strength properties. In conclusion, while sugarcane leaves-based biodegradable materials demonstrate favorable degradation performance, further enhancements are necessary to improve their mechanical properties. These materials have potential applications as substitutes for plastic mulch
Research on Structural Optimization of High-Density Wood Panel Equilibration Chamber Based on Computational Fluid Dynamics
No full textTo guarantee the uniformity of the flow field within an equilibration chamber during the process of hot air baking and to elevate the quality of high-density wood panels, an in-depth analysis was conducted, focusing on the impact of various factors such as the number of side air inlets in the chamber, the spacing between panel gaps, and the configuration of the bottom air inlet spacing. The aim was to optimize the structural parameters to enhance the uniformity of temperature and wind speed. The results indicated that the factors influencing the flow field uniformity within the equilibration chamber were, in descending order of importance, the number of side inlets, the spacing between the bottom inlets, and the distance between the plate gaps. In addition, the optimized hot air increased the average velocity by 0.16 m/s and the average temperature by 6.44K. The percentage of boards passing the inspection of its substandard products was only 9.2%, an improvement of 11.8 percentage points, and the average moisture content was also reduced to 8.76%. The simulation and analysis program effectively improved the uniform distribution of temperature and air velocity in the equilibration chamber and improved the quality of panel production. Therefore, the adoption of this solution helps to achieve efficient drying of wood-based panels and reduce costs
Optimization of Mixed Microbes Pretreatment on Corn Straw for Enhancing Methane Production
No full textIn order to efficiently utilize straw biomass resources, the mixed microbes were used to pretreat corn straw and anaerobic fermentation was carried out. The effects of the straw particle size, the solid-liquid ratio, and the initial pH value on both the pretreatment process and the anaerobic digestion were investigated. On the basis of single factor experiments, the pretreatment conditions were optimized using the response surface method. The pretreatment was conducted at a temperature of 30 °C for a duration of 15 days. The results indicated that the optimal parameters in pretreatment process were as follows: a straw particle size of 20 mesh, a solid-liquid ratio of 1:17, and an initial pH value of 6.5. The predicted cumulative methane production under these conditions was 3740 mL, while the experimental result obtained was (3805 ± 67) mL. With a relative deviation of 1.68% between the predicted and experimental values, the model optimized the pretreatment conditions and improved the prediction of cumulative methane production. The methane yield of corn straw achieved 243 mL/(g-VSadded)
The Influence of the Composition of Pulp and the Number of Layers on the Strength Properties of Multi-Layer Papers Intended for the Production of Corrugated Paperboard
No full textThis research investigated the influence of the layered structure of paper on its selected strength properties. Two types of cellulose pulp were used: unbleached kraft pine pulp (UBSK) and unrefined bleached birch kraft pulp (BHK). Multi-ply papers were obtained from layers of appropriate grammage formed separately and bonded in a wet state. Paper layers were formed from primary pulps (UBSK and BHK) or their mixtures (three-ply UBSK-BHK paper and three-ply UBSK-BHK-UBSK paper), from which various variants of laboratory paper samples were made. This work focused on three-layer papers. The obtained laboratory sheets were analysed for changes in tear resistance, tensile strength, bursting strength, short span compression strength (SCT), and corrugating medium test (CMT). In most cases, three-layer structures were characterised by higher strength parameters than single-layer papers. The tear strength and SCT of papers consisting of three layers formed from both mixed pulps were slightly lower than those of solid papers. The results demonstrate the feasibility of producing three-ply paper with significantly reduced variability in parameters such as elongation and bursting strength, which are inherently subject to high variability.
Chemical Structural Characteristics and Some Mechanical and Physical Properties of Thermally Modified Nothofagus alpina Thinning Wood from Three Different Silvicultural Conditions
No full textThermal modification processes are environmentally friendly methods used to improve certain properties of wood. Currently, wood from thinning of young plantations of Nothofagus alpina (raulí) in Chile is being evaluated to obtain value before the plantation has reached maturity. The objective of this paper was to assess selected properties of thermally modified wood of young (14- to 25-years-old) N. alpina wood that comes from thinning of two sites with intensive silviculture and one similar to a secondary growth forest. To achieve this, non-destructive tests were carried out to measure some chemical-crystalline characteristics, as well as physical and mechanical properties; the differences between the 25%, 50%, and 75% distance from pith to the bark in each site was studied. The modification temperatures used were 170, 190, and 210 °C. The results show that thinning wood from N. alpina can be thermally modified with favorable results, thus presenting an option to obtain value while the plantation reaches maturity, particularly the thinning wood from the intensive forestry regimes, which presented most homogeneous results, especially at the modification temperature of 190 °C
Effect of Delignification Pretreatment and Furfurylation on Practical Properties of Alder Wood (Alnus spp.)
No full textPartial delignification of alder wood specimens was performed with alkaline sulfite and peracetic acid (PAA) methods, and subsequently the delignified samples were saturated with furfuryl alcohol, as an eco-friendly chemical. The aim of delignification before furfurylation was to facilitate the penetration of furfuryl alcohol into the cell wall, in order to overcome the weak mechanical properties and hydrophilicity of alder wood as a fast growing species. The results showed that alkaline delignification removed a lower percentage of lignin despite more significant mass loss as compared to peracetic acid delignification method, which indicates more carbohydrates degradation in alkaline delignification. Infrared spectroscopy also confirmed more retention of carbohydrates in the sample delignified with peracetic acid. The polymerization of furfuryl alcohol in the cell cavities decreased the access of water molecules to the hydroxyl groups of the cell wall, increased the contact angle, and decreasing surface wettability. This effect was more noticeable in the PAA-delignified samples. Mechanical tests revealed that the delignified samples with peracetic acid had higher mechanical strength and modulus, compared to the alkaline sulfite delignified samples. This was attributable to the maintenance of carbohydrates during the delignification process
Effects of Pre-treatment with Commercial Cellulase and Hemicellulase and Laboratory Beating of Unbleached Pine Kraft Pulp on Freeness, Paper Strength, and Fiber Quality
No full textThe effects of laboratory beating on unbleached regular grade pine kraft pulp (UPKP), pre-treated with commercial cellulase/hemicellulase enzymatic preparation (C/HEP) were assessed using degrees of Schopper-Riegler (°SR) and fibre-quality numbers (FQN). The tests showed a significant increase in the °SR (used in papermaking laboratories and industry to assess the degree of beating) of the UPKP after its enzymatic pre-treatment in the amount of 0.25 to 5.0 mL/kg of pulp and beating. However, only a several percent reduction of beating time was observed when the effect of this pretreatment of pulp on the speed of its beating was determined using another method. The treatment of the pulp selected for research with C/HEP before beating negatively influenced its strength properties after this process. The results correlated well with the most important basic fiber properties from the standpoint of papermaking
Effect of Air Heat Treatment on the Color Change and Weight and Density Loss of Six Korean Oak Woods
No full textThe effects of air heat treatment were evaluated on six Korean oak woods: Quercus serrata (Qs), Quercus mongolica (Qm), Quercus acutissima (Qac), Quercus aliena (Qal), Quercus dentata (Qd), and Quercus variabilis (Qv). Color change (ΔE*), weight loss, and density loss were examined using flat-sawn heartwood boards before and after treatment at 160 °C, 180 °C, 200 °C, and 220 °C for 2 h. Overall, the ΔE*, weight loss, and density loss increased with temperature. The properties between temperature and species showed distinct differences. A change to a darker color was observed in all species after treatment at 200 °C. Qm and Qd exhibited the highest and lowest L*, a*, and b* values after treatment at 220 °C, respectively. The highest ΔE* values were obtained in Qd at 160 °C, Qs at 180 °C and 200 °C, and Qv at 220 °C. Qd and Qv exhibited the highest and lowest weight losses at 160 °C, respectively. Qac and Qal showed the highest and lowest weight losses at 220 °C, respectively. Qm showed the highest density loss at all temperatures, whereas Qs had the lowest at 160 °C, and Qac had the lowest values at 180 °C, 200 °C, and 220 °C