Volume 14 Issue 4

A method to measure the contact forces and deformations of mortise and tenon joints based on previous theoretical studies was proposed. The influence of the tenon fits and grain orientations on the contact forces and deformations of the mortises and tenons were studied using this method. The testing method and equations were all introduced in detail. The results showed that the contact force between the mortise and tenon with the tenon in the radial grain orientation was larger than that for the tenon in the tangential grain orientation with the same tenon fit. An exponential relationship between the contact force and tenon fit was found. Also, the deformation of the mortise was 3.6 times smaller than the tenon with a tangential grain orientation and 2.2 times smaller than the tenon with a radial grain orientation.

The spill of crude oil products into the environment has a negative impact on the ecosystem. Sorption materials are utilized as the means of their elimination. The sorption capacity of selected organic and inorganic natural sorbents, such as needles (Larix decidua, Abies alba, and Pinus sylvestris), sawdust from logging (Fagus sylvatica, Picea abies), leaf residues (Fagus sylvatica), moss (Ceratodon purpureus), soil, and synthetic sorbents Absodan Plus, expanded perlite, Eco-dry plus, and Reo Amos were all tested according to the standard ASTM F726 (2012). The natural sorbents were tested at various moisture contents (wet, air-dry, and dry) ranging from 0 to 82%. The pollutant used in the experiment was the low-viscosity engine oil 10W 40. The best sorption capacity among the wet sorbents was achieved with larch needles (11.1 g/g). Moss exhibited the best sorption capacity (25.2 g/g) among the air-dry sorbents. Regarding air-dry sorbents, larch needles, spruce sawdust, and beech sawdust showed the best results. When further dried, their sorption capacity decreased. Soil was the least efficient natural sorbent with a sorption capacity that ranged from 0.45 to 3.82 g/g. The best sorption capacity of 11.5 g/g among the synthetic sorbents was in Reo Amos. The sorption capacity of natural and synthetic substances was comparable.

To investigate the production of cellulases and hemicellulases from Aspergillus niger MTCC9931, solid state fermentation (SSF) was performed using 10 different lignocellulosic materials derived from agrowastes, i.e., rice straw, rice husk, wheat straw, corn cob, sugar cane bagasse, saw dust, banana stalk, Eichhornia, Parthenium stalk, and residual fruit pulp. Among these agrowastes, the maximum yield of reducing sugars (116.46 ± 2.56 g/mL) was observed with residual fruit pulp. Further, the same substrate showed the highest endoglucanase (389.1 ± 0.44 IU/g), MCC-adsorbable endoglucanase (3.4 ± 0.14 IU/g), cellulase (12.0 ± 0.13 IU/g), and FPase (4.9 ± 0.64 IU/g) activities. Sawdust showed the maximum xylanase activity (7478.0 ± 6.51 IU/g), and corncob showed maximum β-glucosidase activity (79.87 ± 1.15 IU/g). The maximum activities of all enzymes were observed at 72 h of SSF under shaking conditions. A. niger MTCC9931 can be concluded to be an important strain for potential applications in saccharification. The enzymatic hydrolysates of the agrowastes were used as substrates for ethanol production by Saccharomyces cerevisiae MTCC174. The maximum yield (35.34 g/L) of ethanol was obtained when residual fruit pulp was used as a substrate. This study has further demonstrated the feasible biotechnological conversion of agrowastes to produce ethanol using both A. niger and S. cerevisiae.

N-doped porous carbon materials derived from bamboo fibers (NBFCs) were synthesized through a simple simultaneous activation and carbonization method. The effects of the adsorbent dosage, absorption temperature, pH of the solution, initial concentration, and contact time on the absorption of methylene blue were investigated. The equilibrium, kinetics, isotherms, and thermodynamics of the adsorption process were also analyzed. The results showed that NBFC-800 had a good adsorption capacity of 816.0 mg/g and a high removal efficiency of 93.3% during the optimum absorption process with an adsorbent dosage of 0.8 g/L, adsorption temperature of 25 °C, initial concentration of 700 mg/L, and a solution pH of 9.0. The adsorption process included instantaneous adsorption or external surface adsorption, intraparticle diffusion, and an equilibrium process. Methylene blue adsorption of NBFC-800 agreed with the pseudo second-order model and belonged to the Langmuir isotherm model. The results will be useful for the development of high-performance NBFCs to efficiently remove methylene blue from wastewater.

Mechanical properties and chemical changes of wood dowel welding were studied using untreated and copper chloride (CuCl2)-treated Betula wood dowels. The effects of the welding times (3 s, 5 s, and 7 s) and the highest temperatures in the welding interface were also studied. The treated wood dowels with a welding time of 3 s and the highest temperature of 265.6 °C had the best pullout resistance. Wood constituents were pyrolyzed by the frictional heat generated from rotational welding to form oxygen-containing materials, most of which were C-O materials. With the extension of welding time, welding interface materials were pyrolyzed deeper, but the rate of pyrolysis decreased, which indicated that the pyrolysis of hemicellulose and cellulose might have occurred in the prior period of the welding process. Acid hydrolysis of hemicellulose and cellulose of the wood dowel treated with CuCl2 might have occurred during immersion, which promoted the formation of molten materials by the depolymerization and pyrolysis of wood constituents. With the same welding time, the content of oxygen-containing materials with treated samples was higher than with untreated samples, which might indicate that more pyrolysis and molten reactions occurred in the treated welding interface.

It is well known that enzymatic hydrolysis is hampered by soluble inhibitors, while lignosulfonate (LS) generated from the sulfite pretreatment could enhance saccharification under certain conditions. To explain the roles of the LS during the hydrolyzing process, two types of LS were tested on selected lignocellulosic substrates and investigated through surface activity analysis and designed hydrolyzing experiments. The results showed that the LS with higher surface activity bound to and saturated the enzyme at a lower dosage and more effectively influenced the enzymatic hydrolysis. Both lignosulfonates, irrespective of their molecular weight and sulfonation degree, inhibited or enhanced the enzymatic saccharification related to two opposing mechanisms, i.e., competitive inhibition by the LS and its beneficial role on the enzyme activity. According to the Michaelis-Menten equation, the rate of cellulase-substrate complex conversion into product did not change with the introduction of the LS, whereas the specific binding affinity of the enzyme to the substrate was noticeably altered. With the introduction of LS, the stability of the enzyme increased, which increased the final hydrolysis yield. The hypothesis that the inhibition effects of LS could be effectively overcome by increasing the substrate content and the buffer concentration of the hydrolysates was confirmed through additional experiments.

A long-acting and slow-release material for chlorine dioxide, based on bagasse pulp (BP) was prepared with a superabsorbent resin as the slow-release substrate and agar as the cross-linking agent. The stable ClO2 solution and the acidic activator were locked into the network structure of the superabsorbent resin, which was prepared with a carboxymethyl cellulose made from bagasse pulp. Because of the network structure of the resin, the diffusion resistance was greatly increased, and the effective release time was up to 2 months. The mechanism for the release process of the ClO2 was explored, and a kinetic model was established based on modified Fick’s diffusion law. The results showed that the release process was a diffusion-controlled process. When compared with a zero-order kinetic model and a Higuchi model, the new established model had better fitting results, and it more fully reflected the release patterns and characteristics of the ClO2.

Corncob, a renewable biomass waste, has been successfully explored as a low-cost crude carbon source to prepare controlled morphology, and result in higher value-added carbons through a ZnCl2/NaCl treatment and direct pyrolysis process. The synthesis route is simple, green, and results in carbons with different morphology and porous structures by varying the ratio of the eutectic salt ZnCl2/NaCl. Moreover, the adsorption capacities of different carbon materials for formaldehyde and butyraldehyde were tested further. It was demonstrated that NaCl and ZnCl2 could be utilized as a mesopore template, and as a micropore activation agent for carbon materials, respectively. Although the mesopores can provide a fast diffusion channel, and the micropores can enhance adsorption ability, the specific surface area originating from the mesopores was proportional to the amount of butyraldehyde adsorption, and the specific surface area of the micropores was beneficial to the amount of formaldehyde adsorption taking place. The adsorption isotherms follow Langmuir and pseudo first-order kinetic modeling. Additionally, the whole process belongs to physical adsorption.

Foam-filled two-dimensional lattice structures were designed, and their compression performance was studied relative to corresponding structures without the foam. The experimental results showed that the compressive load of foam-filled lattice structures improved greatly compared with foam-unfilled specimens. The specific energy absorption (SEA) of foam-unfilled specimens exceeded that of the corresponding foam-filled lattice structure. The maximum energy absorption efficiency of the foam-unfilled lattice structure exceeded 1.5, while that of the foam-filled lattice structure was less than 1. The theoretically predicted compression performance was close to the experimental results. The wood-based lattice structure exhibited excellent specific strength and stiffness compared with other structures.

The unregulated release of titanium dioxide nanoparticles into the environment has raised concern, in particular due to the impact of the nanoparticles on indigenous micro-biome in our ecosystem. This paper reports a study on antifungal activity of titanium dioxide nanoparticles on a healthy growing fungi species, Candida albicans, a known opportunistic pathogen. A quantification of the total cell death was performed using a direct staining method, Trypan blue exclusion assay. Exposure to nanoparticles not only altered the growth rate, but also affected the onset and length of Candida albicans growth phases. The log and the onset of the death phase were shortened and accelerated, respectively. Up to 65% of the Candida albicans were killed after exposure to 100 μg/mL of the anatase titanium dioxide nanoparticles, while only 33% were killed with rutile. A higher dosage and incubation time of the nanoparticles increased their toxicity. Cells suffered from morphological changes upon the nanoparticle exposure, which correlates well with the results showing an altered growth phase culture.