Research Articles

Radial variation in uniseriate ray characteristics of six Korean oak species was observed to provide information for wood identification and quality evaluation. Radial variations in uniseriate ray characteristics, such as ray height, number, and spacing, were observed at five growth ring intervals from the pith to near the bark using optical microscopy. The transition point between the juvenile and mature wood was evaluated using a segmented regression model. All species showed a comparable trend in uniseriate ray number and spacing, gradually decreasing from the pith to near the bark. Transition zones for the six Korean oak species ranged from 21 to 39 years of growth. The highest uniseriate ray heights and spacings were observed in Quercus aliena. Quercus dentata exhibited the highest number of uniseriate rays. Across all species, uniseriate ray number and spacing were higher in juveniles than in mature wood. A negative correlation was observed between the uniseriate ray number and spacing and the uniseriate ray height. The strongest positive correlation was observed between uniseriate ray number and ray spacing. The most reliable parameters for estimating the demarcation point were uniseriate ray number and spacing. The ray characteristics may be used to identify the six Korean oak species.

This study examines the potential of integrating leaching and torrefaction processes to create an enhanced solid biofuel from lignocellulosic biomass. The focus is on evaluating the impact of these combined methods on ash removal efficiency and the melting characteristics of the treated biomass. Two possible strategies were considered: implementing torrefaction first followed by leaching, or conducting leaching first followed by torrefaction. By incorporating both leaching and torrefaction treatments, regardless of order, a solid biofuel with improved properties was attained, especially in terms of higher heating value yield and ash melting temperature compared to individual treatment (either only torrefaction or only leaching). Depending on the sequencing of the leaching treatment, there was a reduction in ash yield from raw biomass ranging between 60% – 86%, while for torrefied biomass it ranged between 47% – 68%. Leaching treatment before torrefaction treatment was determined to be a more effective combination.

The valorization potential of industrial walnut pruning wastes was investigated as a value-added product. Nanofibrillated cellulose (NFC) was prepared from walnut pruning wastes via hydrated choline chloride-lactic acid deep eutectic solvent (ChCl-LA DES) pretreatment followed by grinding, and these were used as paper strength additives. The effect of reaction time on NFC properties were investigated and compared. The structure of nanocellulose was determined by Fourier transform infrared, scanning electron microscopy (SEM), and rheological analysis. The results show that carboxylated NFC having high aspect ratio could be successfully isolated after DES-pretreatment with the average diameter of 39 to 77 nm. Prepared NFC was added to the bulk suspensions of papermaking slurries at various percentages (up to 8%) together with poly(diallyldimethylammonium chloride). The drainage and electrokinetic properties of the pulp and mechanical properties of fabricated handsheets were analyzed and compared. The addition of 1% NFC to the bulk suspensions increased tensile index by 14.2% and burst index by 6.3%. There were further increases observed up to 71.8% in tensile index and up to 72.3% in burst index at 8% NFC addition. Results indicate that DES pretreated cellulose nanofibrils have great potential as reinforcing agent in papermaking.

The effects of pressing time were evaluated relative to the physical, mechanical, and morphological properties of flat-pressed composites made from Gmelina arborea bark and recycled polypropylene (RPP). Bark powder (5% moisture content) was mixed with RPP pellets in a weight ratio of 40:60 with added maleic anhydride (MAH) as compatibilizer. The materials were mixed in a rotary blender for 15 min at speed 80 rpm until homogeneous. The mixture was heated from 175 to 200 °C until RPP pellets were completely melted and then cooled to room temperature. Afterwards, the mixture was made into powder and molded using a steel plate mold at 175 to 200 °C and pressure of 30 kg/cm² for 2, 4, and 6 min to a targeted density of 1.0 g/cm³.  The tested physical properties were covered density, moisture content, water absorption, and thickness swelling. The mechanical properties modulus of elasticity (MOE) and modulus of rupture (MOR), tensile strength parallel to length of panel were also examined. Research results showed that the properties were significantly affected by pressing time and it can be concluded that the optimum condition was obtained at 4 min of pressing.

In China, many tea seeds, the ripe seeds of the tea plant (Camellia sinensis (L.) O. Kuntze), are discarded as agricultural waste. Therefore, the tea seed oil that could have been obtained from tea seeds has also been wasted. To fully understand the content and efficacy of the main active ingredients in tea seed oil (TSO), the chemical composition and activity characteristics of TSO in different areas of Guizhou, China were investigated. The results demonstrated that TSO had high content of unsaturated fatty acids (UFA) and good skincare properties, such as anti-oxidation, anti-ultraviolet, moisturizing, whitening, and bacteriostasis. Furthermore, TSO showed a scavenging effect on reactive oxygen species in mouse fibroblasts cells (L929) and rat cardiomyocytes cells (H9C2). TSO exhibited high biocompatibility and promoted the proliferation and migration of L929. Southwest Guizhou (T4) and southern Guizhou (T6) might be used as high-quality producing areas for cosmetic oil by the weight analysis of each indicator. In summary, as the main producing area of tea in the world, this study helps to alleviate the problem of low oil self-sufficiency in China. The work offers a scientific basis for the in-depth development of TSO, especially in the field of skin care.

The high global market value of fresh mushrooms implies high importance of spent mushroom substrate (SMS) as a by-product that poses environmental challenges, if not properly treated. Reported studies demonstrate the positive effects of SMS on earthworm growth and reproduction, particularly when combined with other substrates such as cow dung (CD). This study utilized SMS and CD as substrates in varying ratios. A total of 375 young non-clitellated Eisenia fetida were randomly assigned to plastic containers, ensuring similar average individual worm weight, and maintained at 50% to 60% moisture. Weekly observations were made on earthworm average weight, cocoon production, and hatchling count. The growth and reproduction of earthworms differed significantly among treatments, with Treatment 3 (T3) (50:50 SMS and CD) showing the highest growth and Treatment 5 (T5) (0:100 SMS and CD) the lowest. Changes in pH, EC, total Kjeldahl nitrogen (TKN), total organic carbon (TOC), C/N ratio, and total available phosphorus (TAP) were observed over the experimental period, indicating dynamic nutrient dynamics within the substrates. The exchangeable potassium decreased with increasing proportions of CD, while the exchangeable sodium content showed variation across treatments. The observed variations can be attributed to differences in initial substrate composition and microbial activity during vermicomposting.

There is a growing demand for wood products from forests located in dry regions, which includes the Caatinga, a biome in Northeast Brazil. This study evaluates the relationship between volumetric production, energy potential, and the rotation cycle. Information was collected from forest stands in different stages of regeneration located in an arid region of Brazil. Based on the forest management plan, four fields were selected with post-logging ages of 9, 11, 13, and 16 years. This inventory recorded circumference at chest height, circumference at base height, total height, volume, stored energy, technical cutting age, and rainfall index. The results showed that the species that presented the most significant quantity of stems did not always correspond to those that obtained the most significant amount of biomass. The technical cutting age was determined at 16 years, aiming to maximize wood utilization. Regarding energy density, the 9-year-old field reached 7,281 kcal ha^-1, the 11-year-old field obtained 14,448 kcal ha^-1, the 13-year-old field recorded 41,526 kcal ha^-1, and the 16-year-old field reached 98,190 kcal ha^-1. The species that contributed most to energy accumulation included Mimosa tenuiflora with 3,740 kcal m^–³, Piptadenia stipulacea with 3,271 kcal m^-3, and Cenostigma pyramidale with 3,101 kcal m^-3.

Polylactic acid (PLA) is a biodegradable polymer extensively used in packaging; however, its mechanical and barrier properties require enhancement for wider applications. Chitin-derived nanoflakes (CNFL), a two-dimensionally separated nanomaterial derived from α-chitin, possess high strength and toughness, making them ideal additives for improved PLA performance. This study investigated the effect of CNFL on the properties of PLA composite films. Incorporating CNFL significantly enhanced the mechanical properties of PLA, increasing its tensile strength and stiffness while preserving flexibility. This enhancement was attributed to the nucleating effect of CNFL, which increases crystallinity. Additionally, CNFL improved the thermal stability of the composite films by mitigating thermal deformation. Notably, the oxygen barrier properties of CNFL-filled PLA composites were also enhanced, demonstrating a significant reduction in oxygen permeability at optimal CNFL concentrations due to increased tortuosity of the oxygen diffusion path. Overall, CNFL-filled PLA composites exhibit great potential as renewable packaging materials, particularly for protecting sensitive products, such as food and pharmaceuticals, from oxidative degradation, thereby extending shelf life and maintaining quality. These findings suggest that CNFL-filled PLA composites are promising materials for advanced applications, offering a combination of enhanced mechanical performance, improved thermal stability, and superior oxygen barrier properties.

This study aimed to develop new composites and evaluate the physico-mechanical properties and formaldehyde content of flat-pressed three-layer particleboard (FPTP) made of bamboo (as a face material) and rubberwood (as a core material) residue bonded with urea-formaldehyde adhesive. Different ratios of core and face material were adopted to investigate the effects of these ratios on the properties of the particleboards. The results indicate that increasing the proportion of rubberwood particles enhanced mechanical properties. All particleboards complied with the maximum permissible thickness swelling percentage (12%) specified in IS 3087 (2005) for Grade 2 category boards. While the moduli of rupture and elasticity values increased with higher rubberwood content, the particleboards did not satisfy the IS 3087 (2005) standard overall. However, the internal bonding strength of T4 (0.5 N/mm²) met the minimum requirement. Nail and screw withdrawal resistance of the particleboards indicated significantly higher resistance with increased rubberwood proportion. Only T4 particleboards met the minimum requirement stipulated by IS 3087 (2005) regarding screw withdrawal resistance for both Grade 1 and Grade 2 category boards. All boards met the criteria for the E₂ classification (formaldehyde content ≤ 30 mg/100 g for oven-dried boards).

The effects of liquid organic fertilizer (LOF) made from anaerobic digestion on some physiological factors and volatile components of arugula plants that were grown in salty conditions were investigated. The experiment was conducted in three different stages. In the first two stages, seeds were grown in petri dishes and pots for seven days. The third stage involved growing seedlings in pots for 60 days. Salinity inhibited the germination of 7-day arugula seedlings in petri dishes and their emergence in pots. In these stages, LOF pretreatment failed to eliminate stress-induced inhibition. Some physiological parameters were analyzed in 60-day seedlings in the third stage. Salt-induced inhibition showed significant negative effects on all parameters. In contrast to previous stages, LOF (1% and 5%) and NPK had positive effects in all groups at the third stage, eliminating salt stress in all parameters except water content. Contrary to expectations, volatile components showed no significant change but had fluctuating values due to salt stress or fertilizer treatments.