Volume 17 Issue 3

The valorization of indigenous flora waste by extraction of biologically active compounds has potential applications in the medical and cosmetic fields. The polyphenols and flavonoids extracted from this waste are valuable compounds for the manufacture of new cosmetic and/or dermato-cosmetic formulas to protect the skin from oxidative stress. This study obtained plant extracts from saffron waste—petals, tepals, and superior portions of stem—using different solid-liquid extraction techniques. The influence of some physical operating parameters was studied (extraction time, solid/liquid ratio, solvent extraction composition). The extraction method performance was assessed by the value of the extraction yields. The obtained extracts were characterized by the content of polyphenols and flavonoids, and the antioxidant activity determined with the DPPH and ABTS methods and the UV-VIS spectrometry. Some emulsions O/W were prepared and preliminarily characterized (pH, sensory analysis, stability after centrifugation and storage). The obtained results showed that the incorporation of this natural extract did not negatively affect the stability of the studied cosmetic formulations and advanced characterization (microbiological control of contamination, rheology studies and in vitro and in vivo studies) can be continued in order to implement a new product.

A new method for predicting wood moisture content using terahertz (THz) time-domain spectroscopy (TDS) is presented in this paper. The THz wave is a promising method in measuring wood moisture content due to its sensitivity to water, impressive penetration ability in wood, and no destructive effect on wood interior. In this study, the selected wood, Douglas fir (Pseudotsuga menziesii), with different moisture content was studied. THz-TDS was used to extract the optical parameter of the sample. The THz refractive index and absorption coefficient spectrum of the wood were calculated. The first and second derivatives of the absorption coefficient spectrum were processed to obtain the first and second derivative spectra. The successive projections algorithm (SPA) was used to select the characteristic frequency for the THz absorption coefficient spectrum and its first and second derivative spectrum of the wood. A regression prediction model of wood moisture content was established by partial least squares regression (PLS). The results showed that the proposed model based on the second derivative spectrum had the best prediction effect for the moisture content of wood.

Strategies based on halo- and thermostable enzymes are promising and attractive for biotechnological applications. Three fungal isolates, namely Aspergillus flavus, Cladosporium cladosporioides, and Alternaria alternata, and were subjected to chitinase production using a medium with different concentrations of NaCl up to 10%. C. cladosporioides was found to be the main chitinase producer at high concentration of NaCl; therefore, its identification was confirmed using 18S rDNA. The highest chitinase production (88.67 U/mL) was obtained by C. cladosporioides, followed by A. flavus (76.17 U/mL), and A. alternata (70.67 U/mL) at 5% NaCl, while their production without NaCl was 35.07 U/mL, 22.83 U/mL, and 21.33 U/mL, respectively. Thermal stability of chitinase was recorded at 50 °C at 20 min. Chitinase halostability at 20 min indicated that 10% NaCl was the optimum level, with activity 88.3 U/mL. Safranin dye decolorization by C. cladosporioides was enhanced to 88.25% via the addition of 5% NaCl to growth medium containing chitin. The inhibitory activity of chitinase was detected against C. lunata and F. oxysporium with or without NaCl. Culex pipiens larvae were more affected by C. cladosporioides chitinase produced at 5% than 10% NaCl. Energy scores of the molecular docking investigations confirmed the insecticidal activity of chitinase against C. pipiens larvae.

Chemical, physical, thermal properties and bonding quality of phenol-formaldehyde resol resin (PF) synthesized with single-walled carbon nanotubes (SWCNTs) was evaluated at varying ratios from 1 wt% to 5 wt%. The effect of the SWCNTs addition on thermal and chemical properties of the PF resins was characterized by thermal gravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy, respectively. FT-IR analysis revealed that the peaks of the modified PF resol resins were similar to those of the reference (laboratory-produced) PF resol resin. These similarities indicated that the synthesis of the resins with phenol, formaldehyde, and carbon nano tubes was successful. The PF resins modified using SWCNTs demonstrated higher thermal stability than the reference PF resin. It was found that the bonding strength of the PF resin containing 3 wt% SWCNTs could reach 12.45 N/mm2 in dry conditions and 7.57 N/mm2 in wet conditions. The bonding test results demonstrated that the SWCNTs were able to improve the bonding performance of the resin under dry and/or wet conditions. This work presents an effective method to improve PF resins with SWCNTs reinforcement for use in the wood and/or polymer composite industries.

Pleioblastus chino var. hisauchii is an important ornamental bamboo species that rarely flowers. Studies on the change in its material properties before and after flowering were lacking. In this paper, the anatomical, chemical, and mechanical properties of bamboo culms before and after flowering were studied by using the method of bio-wood science. The results showed that after flowering, the morphology and proportion of the fiber, vessel and vascular bundle decreased, and the openings of pits in the vessel wall were enlarged significantly; the contents of the main components such as extractives, lignin, holocellulose, cellulose and pentosan rose, while the ash content dropped. There was a decrease in density and modulus of rupture, and a pronounced fall in modulus of elasticity, while the microfibril angle and crystallinity increased. In general, the strength of bamboo flowering culms decreased and the ability to transport nutrients increased, which were closely related to the changes in internal structure and properties. This meant that bamboo flowering may be monitored or predicted by significant changes in some properties (such as pits and modulus of elasticity) and provide a reference for further research on the mechanism of flowering senescence and delayed flowering in bamboo.

The isolation of cellulosic fibers and their applications in composite materials have drawn considerable interest due to their outstanding thermal and mechanical properties combined with light-weight character, biodegradability, and renewability. Bamboo is a fast-growing plant, and its properties include sustainability and excellent tensile strength. In this study, bamboo fibers from the culms and shoots of Dendrocalamus asper were treated with 5 wt% sodium hydroxide and subjected to ultra-sonication for 5 hours to obtain bamboo cellulose. Infra-red spectra showed that lignin and hemicelluloses were removed after treatment. With the removal of amorphous cellulosic regions, both cellulosic fibers exhibited higher decomposition temperatures than the raw fibers. Thermogravimetric analysis confirmed that both types of bamboo cellulose had a peak decomposition temperature at 408 °C. Cellulose isolated from the bamboo shoots exhibited similar chemical and thermal properties, indicating its huge potential as an alternative to mature bamboo culms.

The equilibrium moisture content and specific gravity of Uludag fir (Abies bornmüelleriana Mattf.) and hornbeam (Carpinus betulus L.) woods were investigated following heat treatment at different temperatures and times. Two prediction models were established based on the Aquila optimization algorithm back-propagation neural network model. To demonstrate the effectiveness and accuracy of the proposed model, it was compared with a tent sparrow search algorithm-back-propagation network model, a back-propagation network model, and an artificial neural network. The results showed that the Aquila optimization algorithm back-propagation model reduced the root mean square error value of the original back-propagation model by 87% and 97%, respectively, and the decision coefficients (R²) of the equilibrium moisture content and specific gravity were 0.99 and 0.98; as such, the model optimization effect was obvious. Therefore, this paper provides an effective method for the optimization of the process parameters (such as heat treatment time, temperature, and air pressure) in wood heat treatment and related fields.

Physical and chemical characteristics of bamboo culm heat-treated at low temperature (200 °C to 320 °C) were analyzed to understand their carbonization mechanisms. The physical features and chemical compositions of four Indonesian and one Korean bamboo species were examined, and they were compared with red pine and cork oak after treatment. Weight loss, pH, and calorific value increased with increasing temperature. Weight loss and calorific value of the bamboo species increased from 200 to 240 °C, while those of the wood species increased from 240 to 280 °C. The pH of the bamboo and wood changed from acidic to neutral at 280 and 320 °C, respectively. The crystalline cellulose of the samples in the X-ray diffraction analysis changed to amorphous at various temperatures for each material. In Fourier transform infrared spectroscopy, all species showed a considerable change in hemicellulose peaks at 280 °C and a substantial change in cellulose peaks at 320 °C. In conclusion, the carbonized bamboo culm showed a considerable difference, at 200 °C to 320 °C, in the physical and chemical characteristics.

Results of research on the diversity of wood-rot fungi found in buildings and outdoor wooden engineering structures in Poland are presented in this article. A total of 47 species and genera of wood-rot fungi from Basidiomycota (19 brown rot fungi, 28 white rot fungi) and 1 genus from Ascomycota (1 fungus that does not cause wood decay) were found in damaged buildings. The greatest number of wood-rot fungi was reported on outdoor wooden engineering structures (33 species), followed by unoccupied residential buildings (30 species). The lowest diversity was found in occupied residential buildings (20 species). A total of 34 species and genera of fungi were found in all examined structures, out of which 17 species caused brown rot, 16 caused white rot, and 1 did not cause wood decay.

The synthesis of a microbial flocculant is strictly controlled by its genetic genes, which may be the result of the expression of flocculant genes in the microbial genome. The whole genome of Klebsiella pneumoniae M1 was sequenced for obtaining the mechanism of flocculant synthesis and exploring the mechanism of flocculant production by flocculant bacteria. Therefore, it provided a basis for molecular genetics and functional genomic analysis of flocculants production bacteria. In this way, the mechanism of flocculant production by flocculating bacteria can be better explored. The whole genome sequence of flocculant strain M1 was determined using advanced second generation (Illumina) and third generation (PacBio) sequencing, which was screened from wheat alcohol wastewater. The genes related to flocculant characteristics produced by strain M1 were analyzed for combining with the analysis of flocculant structure characteristics. According to the de novo assembly, a total of 5,511,794 bp clean reads were generated and assembled into 24 contigs. The GC content was up to 58.39%. The genome contained approximately 5383 genes, but 5348 genes had obvious biological functions. A total of 437 genes were involved in carbohydrate metabolism and had coding genes of five carbohydrate-related enzymes. This result indicated that there were functional genes closely related to polysaccharide production in M1 genome. The main metabolic process of flocculant strain Klebsiella pneumoniae M1 was closely related to the potential pathway of extracellular polysaccharide biosynthesis, in which five kinds of carbohydrate synthase genes were involved.