Volume 18 Issue 4

The essential oils of clove species Eugenia caryophyllata (COs) from northern Buru Island were obtained by steam distillation. The chemical components were characterized by gas chromatography (GC-FID) and GC-mass spectrophotometry (MS). In total, five components were identified in COs of leaf, four components were identified in COs of bud, and two components were identified in COs of stem. The main constituents are eugenol (77.1% to 78.8%) and β-caryophyllene (17.0% to 19.6%) in COs of leaf. The main components are eugenol (76.1% to 87.7%) and eugenyl acetate (6.0% to18.9%) in COs of bud and the only main component was eugenol (94.2% to 97.6%) in COs of stem from Waihani (COsWh), Ilath (COsI) and Waimoli (COsWm). The antioxidant activity COs of leaf, bud, and stem was identified using DPPH and ABTS assay. Results showed that COsI of bud had higher ABTS free radical scavenging (IC₅₀ value: 0.09 ± 0.61 μg/mL) than the eight samples in the study. When this activity was compared with synthesis antioxidant of BHT (IC₅₀ value: 0.83 ± 0.54 μg/mL) and AA (IC₅₀ value: 0.81 ± 1.64 μg/mL), the COs in three locations show potential of being used as an antioxidant.

3,4-Dimethylpyrazole phosphate (DMPP) is acknowledged as one of the most efficient nitrification inhibitors (NIs); however, researchers have suggested that its effectiveness needs to be further improved. The authors combined the biostimulant seaweed extract (SE) with DMPP and conducted an indoor incubation experiment to initially investigate the impact of the influence of SE on the degradation and effectiveness of DMPP. Meanwhile, a method for the extraction and determination of DMPP was developed. DMPP performed better, with a longer effective time in loess than black soil, and SE showed a delayed effect on DMPP degradation of DMPP at the beginning of the incubation and then accelerated the degradation process. This was attributed to the adsorption effect of SE on DMPP, consequently reducing its effectiveness. The SE delayed the hydrolysis of urea in various soils; however, no significant impact on urease activity was observed (P < 0.05) (P < 0.05). Furthermore, it also increased potential nitrification rate (PNR) from 10 to 21 days and promoting the rapid transformation of NH₄⁺-N in black soil. The SE reduced PNR within 21 days and inhibited nitrification in loess. In addition, the SE appeared to mitigate the adverse effects of excessive nitrogen on microorganisms The combination of DMPP and SE was not conducive to the inhibition of soil nitrification, and this formulation in field applications requires further investigation.

The main goal of this study was to verify the best combination of density, moisture content, and feed speed on the surface quality of Pinus elliottii boards aimed at deck manufacturing. The secondary goal was to compare three methods of surface quality assessment. Tangential boards were sampled and sorted by density (level 1: 414 kg·m^–³ to 525 kg·m^–³; level 2: 526 kg·m^–³ to 668 kg·m^–³) and moisture content (level 1: 13.5% to 17.5%; level 2: 17.6% to 20.0%). A four-side planer molder was used, at three levels of feed speed (15, 20, and 25 m·min^-1). Surface quality was assessed immediately after machining by visual-tactile analysis, stylus surface profilometer reading (parameters R_a, R_z, and R_t), and feed per tooth (f_z) measurement. The best surface quality results were obtained with denser (526 kg·m^–³ to 668 kg·m^–³) and wetter boards (17.6% to 20.0% moisture content) at feed speed 20 m•min^-1. This recommendation represents an optimal balance between the quality standard of the deck boards and high productivity. Because of the low cost and because it has some correspondence with the stylus surface profilometer readings, visual-tactile analysis is recommended to assess the surface quality.

Castor oil is a widely used biomass energy source. In this paper, the process conditions for the preparation of sebacic acid by cracking castor oil using the microwave method were investigated using environmentally friendly and recyclable liquid paraffin (petrolatum) as a solvent. The optimum conditions for the reaction were determined in the experiments as follows: the mass ratio of solvent: castor oil: sodium hydroxide was 4:1:2.5 and the concentration of sodium hydroxide solution was 50% (w/t). The average microwave power was 210 W, the temperature was about 280 °C, the cracking time was 25 min under nitrogen protection, and the yield of sebacic acid was measured to be 85%. The solvents can be recycled and the recovered solvent can be used again without affecting the yield of sebacic acid. The solvent recovery was more than 92%.

In laboratory practice, several standards for testing the bending stiffness of corrugated board are used. There are often cases of tests where the results depend on the way the sample is placed on the supports. The problem arises when the board is five-ply (with two corrugated layers with different corrugation heights) or when the board has asymmetrically selected papers on the flat layers. This article focuses on the problem related to boundary conditions, with particular attention to the local effects of the support of the sample. Because the cardboard layers, both flat and corrugated, have a small thickness, a slight deformation of the papers can always be observed at the point of contact between the sample and the support, which affects the readings of the measured stiffness. The paper presents theoretical and numerical analyses showing how much the method of supporting the sample affects the measured bending stiffness of various samples. Numerical observations were compared with the results of analyses presented by other scientists as well as with experimental results.

Structural systems built from raw bamboo have been used for years due to its highly renewable characteristics, versatility, and abundance in various countries, e.g., China, Indonesia, all over South America, and especially Brazil. It is also considered a low specific weight material, which means it is easy to handle and transport. These characteristics make it a low-cost material for building construction. The objective of this systematic bibliometric review is to identify innovations in bamboo culms structural connections in order to contribute to the advancement of technology applied to civil construction by seeking joints that consider the use of industrialized or standardized products. This review revealed there is still no ideal connection capable of solving the great problem of this subject, which points out the need for more studies on the topic. This investigation also allows for the classification of the connections into 5 categories: Bolted connections; Steel member and Steel plate connections; Reinforced Connections with filler; Parameterized connections, and; Connections with the use of wooden dowels.