Effect of NaOH Pretreatment on Permeability and Surface Properties of Three Wood Species.

To improve the permeability of wood, three chemical reagents were used to pretreat Chinese fir, white oak, and poplar. Through a factorial experiment with the mass change rate of the wood as the indicator, NaOH was preliminarily selected as the pretreatment agent. Further orthogonal experiments were conducted to explore the effects of NaOH concentration, temperature, and treatment time on the mass change rate, dye uptake rate, transverse dye penetration rate, and color difference of the wood. A fuzzy, comprehensive analysis was used to optimize the pretreatment process. The results showed that after NaOH pretreatment, the highest mass change rates of Chinese fir, white oak, and poplar were 11.30, 10.66, and 8.53%, respectively. Compared with untreated wood, the dye uptake rate of three wood species increased by 1.05, 1.43, and 1.13 times, respectively; the radial dye penetration rate increased by 5.05, 4.14, and 3.38 times, respectively; and the tangential dye penetration rate increased by 3.91, 3.45, and 3.84 times, respectively. These findings indicate an enhancement in permeability for all three wood species following NaOH pretreatment. The brightness of the three wood species decreased after NaOH pretreatment, while the yellow and red colors increased in Chinese fir and poplar and decreased in white oak. Scanning electron microscopy showed that pits in the wood opened after pretreatment, while extractives decreased. Infrared spectroscopy analysis indicated varying degrees of extraction effects from NaOH pretreatment across the three wood species, along with increased active hydroxyl groups within the wood structure. X-ray diffraction analysis revealed that NaOH dissolved noncrystalline substances in wood, leading to improved crystallinity. These experimental findings provide essential data for future endeavors in wood pretreatment and subsequent staining processes.

Species and release characteristics of VOCs in furniture coating process.

Volatile organic compounds (VOCs) are an important factor affecting ambient air quality, and furniture production is one of the important sources of VOC pollution. High VOC concentrations have adverse effects on the environment and worker welfare in furniture factories. In order to control VOC emissions in a furniture workshop, the VOC species and concentration distributions were examined. Qualitative analysis of VOC species was carried out by headspace gas chromatography/mass spectrometry. The results showed that VOCs from a furniture workshop were mainly 12 substances including acetate, toluene, and xylene compounds. The heights and representative positions of VOCs released during the coating process were determined, and the results showed that VOC concentrations depended on environmental and height factors. The concentration of VOCs decreased with increasing altitude and reached a maximum concentration at 0.4 m above the ground. Because the concentration of VOCs varied with temperature, humidity, air pressure, and amount of spray paint, this paper established functional relationships between VOC concentrations and temperature, humidity, air pressure, and amount of spray paint. These results provide a theoretical basis for furniture workshops to automatically monitor and control VOCs. MAIN FINDING OF THIS WORK: VOCs from the furniture workshop were mainly composed of 10 substances including acetate, toluene, and xylene compounds.

Variation of plantar pressure in Chinese diabetes mellitus.

To investigate dynamic changes in plantar pressure in Chinese diabetes mellitus patients and to provide a basis for further preventing diabetic foot. This is a cross-sectional investigation including 649 Chinese diabetes mellitus patients (diabetes group) and 808 "normal" Chinese persons (nondiabetes group) with normal blood glucose levels. All the subjects provided a complete medical history and underwent a physical examination and a 75-g oral glucose tolerance test. All subjects walked barefoot with their usual gait, and their dynamic plantar forces were measured using the one-step method with a plantar pressure measurement instrument; 5 measurements were performed for each foot. No significant differences were found in age, height, body weight, or body mass index between the two groups. The fasting blood glucose levels, plantar contact time, maximum force, pressure-time integrals and force-time integrals in the diabetes group were significantly higher than those in the nondiabetes group (p < 0.05). However, the maximum pressure was significantly higher in the nondiabetes group than in the diabetes group (p < 0.05). No difference was found in the contact areas between the two groups (p > 0.05). The maximum plantar force distributions were essentially the same, with the highest force found for the medial heel, followed by the medial forefoot and the first toe. The peak plantar pressure was located at the medial forefoot for the nondiabetes group and at the hallucis for the diabetes group. In the diabetes group, the momentum in each plantar region was higher than that in the nondiabetes group; this difference was especially apparent in the heel, the lateral forefoot and the hallucis. The dynamic plantar pressures in diabetic patients differ from those in nondiabetic people with increased maximum force and pressure, a different distribution pattern and significantly increased momentum, which may lead to the formation of foot ulcers.