Lignin–carbohydrate complexes (LCCs) have shown
antioxidant
ability to scavenge the individual free radicals in vitro, while little work has been carried out to show if the LCCs can
efficiently scavenge the intracellular and endogenous reactive oxygen
species (ROS), which are the multiple radicals derived from the reduction
of molecular oxygen during the metabolism process. In this work, carbohydrate-rich
LCCs from bamboo (LCCs–B-B) and poplar (LCCs–B-P) were
isolated according to the classical method, and their antioxidant
activities were evaluated by scavenging intracellular ROS in RAW 264.7
cells in vitro and endogenous ROS in zebrafish in vivo. Results from composition analysis show that both
LCC preparations possess similar contents of carbohydrate (52.2% and
51.2%) and lignin (44.1% and 47.8%). However, NMR analysis revealed
that the LCCs–B-B contain 16.1/100C9 LCCs linkages,
higher than that in LCCs–B-P (12.3/100C9). Antioxidant
assays indicated that LCCs–B-B exhibited better antioxidant
activities for scavenging the individual free radicals. At the cellular
and animal model levels, LCCs–B-B also outperformed the performance
of LCCs–B-P in scavenging the endogenous ROS in H2O2-stimulated RAW 264.7 cells in vitro and zebrafish in vivo, which may be due to its
better ability to prevent the reduction of antioxidant enzyme activity
(superoxide dismutase and glutathione peroxidase) in oxidative stress.
Gravity-feed drilling is the most commonly used method for micro-hole drilling in glass with spark assisted chemical engraving (SACE). This paper proposes a method allowing the systematic characterization of this drilling method. The influences of voltage, tool shape and force are investigated. It is found that SACE gravity-feed drilling shows two regimes depending on the drilling depth. During the first 200–300 µm, the discharge regime, controlled by the number of discharges inside the gas film, allows fast drilling (up to about 100 µm s−1). For deeper depths, the drilling is controlled by the hydrodynamic regime in which the drilling speed is limited by the flow of the electrolyte inside the micro-hole resulting in slow drilling of typically 10 µm s−1. Furthermore, it is shown how the gas film build-up time is limiting the drilling speed.
The aim of this study is to examine the wettability and thermal properties of individual bamboo fibers after alkali treatment. The individual bamboo fibers were treated by sodium hydroxide (NaOH) solution with varying concentrations (6, 8, 10, 15 and 25%) followed by freeze-drying treatment. The surface analysis of alkali-treated individual bamboo fibers was characterized by atomic force microscope. Water droplet on the individual fiber surface was observed with drop shaper analyzer and the contact angles on fiber surface were also measured. Thermal properties were further studied by thermogravimetric analysis. The results indicated that alkali treatment resulted in the increase in surface roughness of individual bamboo fibers. Alkali treatment with low NaOH concentration could enhance the wettability of treated individual bamboo fibers, and while the wettability was reduced with alkali treatment at high concentration (25%). Thermal analysis revealed that the onset of decomposition and the maximum decomposition were moved to higher temperature after alkali treatment at low NaOH concentrations (6, 8, and 10%), suggesting the improvement in the thermal stability of treated individual bamboo fibers, while the thermal stability was compromised after alkali treatment at higher concentrations (15 and 25%).
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