Volume 14 Issue 3

This study investigated the antibacterial activity of nano-zinc oxide (ZnO) composite hydrogels on the types of mold organism that commonly affect bamboo. The nano-ZnO was produced via the in situ method in poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAm-co-AAc)) hydrogel. The structures and properties were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), differential scanning calorimeter (DSC), equilibrium swelling ratio (ESR), deswelling and swelling tests, and antimicrobial activity. The nano-ZnO particles were monodispersed in the P(NIPAm-co-AAc) hydrogel. The concentration of the nano-ZnO was higher in the ZnO/P(NIPAm-co-AAc) hydrogel than in the ZnO/PNIPAm hydrogel. The swelling properties in the ZnO/P(NIPAm-co-AAc) hydrogel were more favorable than those of the ZnO/PNIPAm hydrogel, while the deswelling properties were more favorable in the ZnO/PNIPAm hydrogel. The hydrogels that contained more ZnO nanoparticles demonstrated greater antimicrobial properties against Trichoderma viride and Penicillium citrinum of bamboo, while the all of the hydrogels had much less antimicrobial activity against Aspergillus niger.

Water-based epoxy resin emulsion was prepared by emulsifying o-cresol formaldehyde epoxy resin with self-emulsified epoxy curing agent synthesized in this study and then used as an environmentally friendly binder for automotive air filter paper. The preparation process of the self-emulsified epoxy curing agent was confirmed by Fourier transform infrared spectroscopy (FTIR). The effects of neutralization degree (Neu) and amount of curing agent on the formation of epoxy resin emulsion were studied. The micro-morphology and size distribution of the epoxy resin latex were characterized by transmission electron microscopy (TEM) and dynamic and static light scattering, respectively. The micro-structure of the air filter paper surface was studied by scanning electron microscope (SEM). The mechanical strength and moisture-resistance properties of air filter strengthened by the prepared water-based epoxy resin emulsion was tested and compared to three commercial binders. The prepared epoxy resin emulsion greatly enhanced the mechanical properties and moisture-resistance properties of the air filter paper while maintaining its filtration properties. Therefore, the epoxy resin emulsion can be used as an environmentally friendly water-based binder for automotive air filter paper with excellent comprehensive properties.

Water and potassium are limiting factors for tree growth. Their influence on morphology and anatomy are well known, but their combined effects on tree growth remain to be clarified. A single clone of Eucalyptus grandis was analyzed under different treatments of rainfall exclusion and fertilization. Eight trees per treatment were sampled to investigate the influence of these treatments on the morphological, mechanical, and anatomical traits. The results showed that the fertilization mainly influenced the morphological and anatomical characteristics. Considering the difference between the fertilized and non-fertilized trees, the function of mechanical support was provided through increasing the diameter and the stiffness. Considering the fertilized trees, two different mechanisms occurred inducing a high stiffness: the wood density was higher for trees with rainfall exclusion; the specific modulus was higher for trees with a normal water supply.

The objective of this study was to design and develop a novel type of modular bamboo-composite wall using bamboo bundle veneer/wood veneer laminated composite (BLVL) with excellent physical and mechanical properties. The physical and mechanical properties of the important component of the bamboo-composite wall, BLVL, were characterized and the thermal insulation properties of three types of walls composed of different thickness of structural layers were studied. The results showed that the physical-mechanical properties of BLVL-composite walls were excellent. For BLVL wall panels, parallel and perpendicular to the glue layer, the static bending strength and elastic modulus were 137.8 MPa and 124.1 MPa vs. 1.37 GPa and 1.06 GPa, respectively. The internal bonding performance of BLVL was 3.07 MPa, 3 times greater than the standard requirement. The total heat transfer coefficients for models І and II of the bamboo-composite walls were 0.46 and 0.43 W/(m2·K), respectively, in line with the requirements of the “Public Building Energy Efficiency Design Standards” GB/T 50189-2005. The development of novel bamboo composite wall and its promotion and application in fabricated buildings have important market prospects and ecological and social values.

Lacquer, bone glue, and poly(vinyl acetate) (PVAc) were selected in this work as the reinforced binding components for the restoration of lacquer furniture. Three response variables related to the strength of the binding material were studied: cohesive strength of lacquer film, binding situation, and the permeation of adhesive. In addition to mechanical tests, specimens were observed directly and by scanning election microscopy (SEM). The cohesive strength of lacquer film attached by lacquer, bone glue, and PVAc was evaluated on specimens with three kinds of ground layer, including stucco with pig-blood, stucco with lacquer, and the ground layer with titanium dioxide. The permeation of lacquer, bone glue, and PVAc could be determined by SEM. The results shows that strong reinforcement can be achieved by strong cohesive strength of lacquer film, a suitable binding situation, and suitable permeation of the adhesive. Intermediate strength is obtained in the case of intermediate cohesive strength, an intermediate binding situation, and less then optimal permeation. Weak reinforcement results from weak cohesive strength, a poor binding situation, and insufficient permeation.

Coconut shell activated carbon (AC) loaded with MnO2 was tested as an adsorbent for formaldehyde. Preparation conditions of MnO2-loaded AC (MnO2-AC) were optimized. The resulting AC and MnO2-AC were characterized by scanning electron microscopy, Brunauer-Emmet-Teller analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometry, and X-ray diffraction. The results showed that the adsorption efficiency of formaldehyde (3.5 mg/L) by MnO2-AC (concentration of manganese nitrate/sodium carbonate was 0.3 mol/L, impregnation oscillation time of 4 h, calcination temperature and time of 350 C and 4 h, respectively) was 93.1%, which increased by 251% compared to that of the AC. The adsorption equilibrium of MnO2-AC was achieved after 4 h. With increasing dosage of MnO2-AC, the rate of increasing of the adsorption efficiency became more gradual. The adsorption process of the formaldehyde solution with a low concentration fit the Langmuir adsorption isothermal model, where the adsorption capacity was 9.22 mg/g. The stability and regenerability of MnO2-AC were good.

A photocatalyst with high reactivity was prepared in liquid phase through the in situ deposition of TiO2 on cellulose-based graphitic material that had been oxidized via Hummers’ method that was followed by a heating treatment at 200 °C. The composite had excellent photocatalytic activity for degrading methyl orange (MO), and reducing hexavalent chromium (Cr(VI)) under ultraviolet irradiation as well as the reported graphene oxide/TiO2 composite. Under the optimal condition, the reaction rates for treating MO and Cr(VI) using the new catalyst system were 4.6 and 1.6 times higher, respectively, than that of commercial TiO2 (P25). In addition, the composite had good catalytic activity in acid solutions. Unlike the reported graphene oxide/TiO2 composite, TiO2 nanoparticles in the prepared composite aggregated to large particles of approximately 1 μm in size on the carbon substrate. When synthesized in the same procedure from other biomass materials, such as lignin, walnut shell, or fir sawdust, the composite had much lower reactivity, similar to that of neat TiO2; the lower graphitic degree of those materials might be the reason for the disparity in reactivity.

In order to investigate the relationship between production parameters and evaluation indexes for wood fiber production, a bi-directional prediction model was established to predict the fiber quality, energy consumption, and production parameters based on the improved particle swarm optimization and support vector machine (IPSO-SVM). SVM was applied to build the bi-directional prediction model, and IPSO was used to optimize the SVM parameters that affect the performance of prediction greatly. In the case of the forward prediction, the model can predict the fiber quality and energy consumption using the production parameters as input information; in the case of the backward prediction, the model can estimate production parameters using the fiber quality and energy consumption as evaluation indexes for input information. The results showed that the IPSO-SVM model had high accuracy and good generalization ability in the prediction for the wood fiber production. Additionally, based on the effectiveness of the proposed model and preset evaluation indexes, the corresponding production parameters were determined, which was able to save the wooden resources as well as reduce energy consumption in the fiberboard production.

Cross-laminated timber (CLT) construction has received significant attention for potential North American markets; however, few claims have been substantiated with structural design details that assess the amount of CLT to be used in various classifications of buildings. This article presents a design process used for the development of archetype buildings to estimate the potential CLT demand. Three types of structural systems were identified: platform construction, rocking walls with a separate gravity system, and hybrid construction consisting of reinforced concrete elevator cores and rocking walls. Platform construction was used for buildings 1 to 6 stories in height, the rocking wall system was used for buildings 6 to 12 stories in height, and the hybrid structural system was used for buildings 12 to 18 stories in height. The assumptions and design process for each of these archetypes are presented in this paper. Based on the structural analyses, CLT use factors were developed for predicting market demand as well as cost estimation of CLT building projects.

Alpha-glycosidase degrades polysaccharides and oligosaccharides and participates in the synthesis of oligosaccharides through a process called transglycosylation. In this study, an α-glycosidase gene pthgly from Pseudothermotoga thermarum was cloned using pET-20b as a vector and was expressed in E. coli BL21(DE3). After heat treatment and affinity chromatography, the resulting recombinant enzyme was purified. The purity of the enzyme reached a single band at a molecular weight of approximately 55 kDa. The properties of the recombinant enzyme were determined. The optimal temperature of α-glycosidase (Pthgly) was 90 °C and the optimal pH was 7.5. In addition, Pthgly exhibited good thermal stability at 70 °C and 75 °C. The relative molecular mass of the recombinant enzyme was 116 kDa, as determined by a protein purification system with a gel filtration column. Furthermore, α-glycosidase possessed Michaelis-Menten kinetics with a Km and Vmax of 0.29 ± 0.01 mmol l-1 and 22.12 ± 1.31 μmol min-1 mg-1, respectively.