Volume 15 Issue 2

A process of simultaneous saccharification and protease production was successfully established from spent mushroom compost (SMC) created through edible fungi cultivation. The combined water extraction and sodium chlorite pretreatment significantly (p < 0.05) improved enzymatic digestibility of SMC, which led to a reducing sugar yield of 0.759 g/g that was 12 times higher than raw SMC. The water extract from SMC was recycled for simultaneous saccharification and protease production from pretreated SMC by Bacillus subtilis DES-59, which promoted the protein concentration and neutral protease activity by 21.9% and 11.6%, respectively. The simultaneous saccharification and co-fermentation (SScF) of pretreated SMC by Bacillus subtilis DES-59 produced 5518 U/mL protease, which was superior to the separate hydrolysis and fermentation (SHF) process. Fermentation residues containing Bacillus subtilis cells could be further converted into fertilizer. The closed-loop utilization of SMC was achieved using established processes, which indicates potential for application in future biorefineries.

Parallel strand bamboo (PSB) is a new type of bio-composite. In the present study, three-point bend end-notched flexure (3ENF) tests of PSB were conducted to analyze the fracture behavior including fracture process, resistant curves, and critical energy release rate in the longitudinal (L) system. The results show that transverse-longitudinal (TL) and thickness-longitudinal (ZL) specimens had the same fracture process including the stages of fracture process zone (FPZ) development and opening crack propagation but different mode II critical energy release rate (GIIc), and they indicate that the fiber bridging had a significant influence. The fracture processes suggest the PSB specimens of which the initial crack length was 0.5 times the half span had a stable crack propagating process, and the crack propagation length was wide enough to evaluate GIIc, which was 5.02 N∙mm-1 of TL specimens and 2.71 N∙mm-1 of ZL specimens. Besides, there was no obvious influence of span/depth ratio on the fracture resistance of both ZL and TL specimens when the ratio was larger than 15.

The chemical characteristics of lysates obtained from yeasts belonging to Metschnikowia spp. were determined. Cell lysis was induced using saponin from Q. saponaria or 5% NaCl. The process was conducted at 50 °C for 24 for 48 h. The enzymatic profiles of the resulting lysates were analyzed. The mannose and glucose contents were also investigated, as well as the concentrations of proteins, free amino nitrogen (FAN), and free amino acids. The results were compared to the characteristics of lysates from conventional industrial strains of Saccharomyces spp. obtained under analogous conditions. The Metschnikowia lysates showed different chemical profiles and the pool of individual amino acids was generally smaller. However, the content of hydroxyproline HPro was 4 to 5 times higher. The results of this study show that yeast lysates are an attractive supplement for numerous applications.

Biochar was synthesized from biomass (jatropha seeds) through a low microwave pyrolysis temperature of 180 °C with microwave power of 2kW. A ball milling process reduced the jatropha seed biochar size and converted it into micro-nano carbon biofiller. After ball milling, the biochar size was reduced from 1 to 3 mm to the 10 µm to 600 nm range, which is around a 90% reduction in size. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) analysis were used to determine the jatropha seed biofillers properties with respect to the ball milling processes. BET results revealed increasing surface area from 0.10 to 3.67 m2/g, and EDS results revealed the elemental composition of the jatropha seed biofillers. The carbon mass percentage increased from 72.6 to 81.2%. Both results were after ball milling for 30 hours. The FTIR results revealed an increase in transmittance intensity and some reduction in peaks after ball milling. Production of micro-nano carbon fillers from microwave pyrolysis jatropha seeds biochar are applicable as reinforcement fillers for high strength composite material fabrications. Scanning electron microscopy, EDS, FTIR, and BET analysis results indicated size reduction of the biochar with increased carbon content from 72.6 to 81.2% as surface area increased from 0.10 to 3.67 m2/g after 30 hours of ball milling.

An alternative approach to producing a wood-plastic composite (WPC) from wood particles, aluminium trihydrate-filled poly(methyl methacrylate) (PMMA/ATH) waste powder, and melamine-urea-formaldehyde (MUF) resin is described. The surface of PMMA/ATH powder was modified with ureido- and amino-functional silane coupling agents at four different degrees of modification: 0.3%, 0.5%, 1.0%, and 2.0%. An X-ray photoelectron spectroscopy (XPS) analysis was executed on a silane-modified PMMA/ATH material, and the results revealed the presence of chemically bonded silanes on the PMMA/ATH surface. Contact angle measurements were also performed to calculate the surface free energies of the modified powders. Water contact angles of modified powders slightly decreased as surface free energy increased with the degree of surface modification. Mechanical tests of the composites showed that different degrees of surface modification had a significant influence on modulus of elasticity (MOE) and modulus of rupture (MOR) of the composite boards. However, there were no significant differences between the silanes used.

In order to accurately and reliably optimize the process parameters of ultra-high pressure water jet cutting for wood, water jet processing was conducted on red oak and bamboo floor specimens, and the materials were scanned for three-dimensional surface topography. The surface roughness value of the cut surface of the test piece was measured by the orthogonal measurement method as an evaluation index to determine the optimal arrangement of the influencing factors and the process parameters. Finally, the water cutting mechanism and three-dimensional shape of the processed test piece were analyzed. The factors affecting were as follows: cutting pressure > feeding speed > abrasive flow rate > target distance > air-dry density. The optimal experimental scheme included an abrasive flow rate of 35 kg/h, cutting pressure of 310 kPa, feed speed of 250 mm/s, target distance of 3 mm, and air dry density of 620 kg/m3. Under these processing conditions, the surface roughness values of water jet red oak and bamboo specimens were relatively small, and the processing quality was the best. The results of the above-mentioned research can provide a reference for the research and application optimization design of wood and bamboo processing for ultra-high pressure water jet technology.

Accurate estimation of average modulus of elasticity in compression parallel to the grain (Ec0) is of paramount importance for rational sizing of timber structures, given the use of this property in the estimation of stability of compressed parts (ultimate limit state, ULS) and in calculation of excessive strains (serviceability limit state, SLS). In Brazil, if values cannot be experimentally determined, ABNT NBR 7190 (1997) allows for estimation of Ec0 through relations to average modulus of elasticity both in tension parallel to the grain (Et0) (Ec0 = Et0) and in bending (EM) (Ec0 = EM/0.90). This research aimed to access the efficiency of these relations by testing 30 tropical wood species. The analysis of variance results showed that Ec0 and Et0 were statistically equal. However, Ec0 and EM/0.90 were not statistically equal, and the method of least squares resulted in a coefficient of 0.98, which was 8.89% higher than the one suggested by ABNT NBR 7190 (1997) and close to 1, thus, validating the results of ANOVA, which pointed on the equivalence between Ec0 and EM (Ec0 = EM). As an alternative to simplified equations of the standard, two-parameter regression models were used. The geometric model with R² = 91.67% proved to be the model of best fit, which demonstrated that Ec0 could be calculated as a function of EM.

The influence of copper and its nanoparticles was studied relative to growth and ultrastructure of Aspergillus niger. Laccase production by A. niger using corn cobs as substrate at different concentrations of CuSO4 and copper nanoparticles (CuNPs) is reported. Fungus growth was induced at 100 ppm of CuNPs and CuSO4, while at 300 ppm, the growth inhibition was 65.6% and 86.9%, respectively. Fungus sporulation was reduced to 30.4% and 47.6% at 300 ppm of CuNPs and CuSO4, respectively, compared to the control (100%). Transmission electron microscopy revealed that CuSO4 and CuNPs treatments encouraged the deformed appearance of the fungus at 200 ppm and 300 ppm, particularly CuNPs. The CuNPs and CuSO4 induced laccase production at 1.67 U/mL and 1.51 U/mL at optimum concentrations 0.15 mM and 0.25 mM, respectively. The optimum concentrations of CuNPs and CuSO4 led to reduced incubation periods of 12 d and 14 d, respectively, required to produce the highest amount of laccase (1.66 U/mL and 1.53 U/mL), while without treatments, the incubation period increased to 16 d required for the highest amount of laccase production (1.36 U/mL). Induction of laccase production at acidic pH and at 30 °C was recorded with the addition of CuSO4 and CuNPs, while its effects were slight at pH above 6.

Flexible hydrogels with an adjustable Poisson’s ratio were prepared, offering a way to simulate the behavior of natural organisms, expressing corresponding deformation in response to external forces. Nanofibrillated cellulose (NFC) particles were blended with photo-curable resin poly(ethylene glycol) diacrylate (PEGDA), and flexible NFC/PEGDA hydrogels with positive, near zero, and negative Poisson’s ratios (0.66 ± 0.31, 0.17 ± 0.28, and -0.39 ± 0.26, respectively) and were successfully prepared using masking and photocuring. Furthermore, the effects of different curing times and mask apertures were investigated. The clarity and structural precision of the hydrogels were used to evaluate the effects of the preparation procedures. A curing time of 20 s and a mask aperture of 5 mm were the ideal conditions for preparation of NFC/PEGDA hydrogels. Further, addition of NFC resulted in excellent hydrogel flexibility and enhanced mechanical properties. The fabrication of NFC/PEGDA hydrogels with high structural precision and tunable Poisson’s ratios has the potential for application in wearable devices and intelligent monitoring equipment.

Corporate culture represents a personality of a company. Suitable corporate culture should be a summary of behavior and action of the company as a whole and its individual employees on their way to achieving the strategic goals of the company. Using the Organizational Culture Assessment Instrument methodology, the corporate culture on a sample of 1,114 respondents in wood-processing and forest enterprises in Slovakia is defined and compared. The hypothesis that there were statistically significant differences between wood-processing and forest enterprises in individual components of corporate culture is confirmed in the paper. The differences in the perception of corporate culture in the area of organizational leadership and criteria of success can be considered the research output. In the area of organizational leadership, there are significant differences in the respondents’ opinions. In the area of criteria of success, employees of the wood-processing enterprises preferred the success of these companies based on the development of human resources and teamwork. There were no significant differences in the area of overall corporate culture. Both groups of employees preferred clan corporate culture.