Simultaneous production of furfural, lignin and cellulose-rich residue from Eucalyptus urophylla × E. grandis by ChCl/1,2-propanediol/MIBK biphasic system pretreatment.

A facile biphasic system composed of choline chloride (ChCl)-based deep eutectic solvent (DES) and methyl isobutyl ketone (MIBK) was developed to realize the furfural production, lignin separation and preparation of fermentable glucose from Eucalyptus in one-pot. Results showed that the ChCl/1,2-propanediol/MIBK system owned the best property to convert hemicelluloses into furfural. Under the optimal conditions (MRChCl:1,2-propanediol = 1:2, raw materials:DES:MIBK ratio = 1:4:8 g/g/mL, 0.075 mol/L AlCl3·6H2O, 140 °C, and 90 min), the furfural yield and glucose yield reached 65.0 and 92.2 %, respectively. Meanwhile, the lignin with low molecular weight (1250-1930 g/mol), low polydispersity (DM = 1.25-1.53) and high purity (only 0.08-2.59 % carbohydrate content) was regenerated from the biphasic system. With the increase of pretreatment temperature, the ß-O-4, ß-ß and ß-5 linkages in the regenerated lignin were gradually broken, and the content of phenolic hydroxyl groups increased, but the content of aliphatic hydroxyl groups decreased. This research provides a new strategy for the comprehensive utilization of lignocellulose in biorefinery process.

Microwave-assisted choline chloride/1,2-propanediol/methyl isobutyl ketone biphasic system for one-pot fractionation and valorization of Eucalyptus biomass.

The developing of pretreatment method to break the biomass barrier of lignocellulosic is a challenging task for achieve high value utilization. A fast microwave-assisted choline chloride/1,2-propanediol/methyl isobutyl ketone biphasic system was constructed for pretreating Eucalyptus to the production of furfural and cellulose-rich residues and the extraction of lignin. Results showed that the combination of AlCl3·6H2O and HCl had the best catalytic ability for furfural production among the examined catalysts. Under the optimal conditions (140 °C, 15 min, 0.075 M AlCl3·6H2O, 0.05 M HCl), the furfural yield of 55.4 %, the glucose yield of 90.3 % and the delignification rate of 92.4 % could be achieved. Moreover, the extracted lignin samples with a low polydispersity (1.55-1.73) and molecular weight (1380-2040 g/mol) are promising to act as precursor for the value-add products processing. These findings demonstrated an ultrafast pretreatment process with excellent results in biomass fractionation and comprehensive utilization of biomass components.

Structure of corn bran hemicelluloses isolated with aqueous ethanol solutions and their potential to produce furfural.

The alkali-soluble hemicelluloses extracted with 10% KOH solution from corn bran were further isolated with different concentrations of aqueous ethanol solutions. Herein 92.2% of the original hemicelluloses can be obtained and the cellulase enzymatic hydrolysis rate of the alkali treated corn bran can reach to 97.2%. The corn bran hemicelluloses were mainly glucuronoarabinoxylan, in which xylose (48.4-53.8%) and arabinose (27.8-33.2%) were the main components. More linear hemicelluloses with high molecular weight tended to be precipitated in low concentration aqueous ethanol solutions. Furthermore, the relationship between the structural features of these alkali-soluble corn bran hemicelluloses and their furfural yield was investigated in MIBK (methyl isobutyl ketone)/H2O biphasic system. Results showed that the hemicelluloses with high xylose content are benefit to the furfural production, and the highest furfural yield of 67.7% was obtained.

Exploration of deep eutectic solvent-based biphasic system for furfural production and enhancing enzymatic hydrolysis: Chemical, topochemical, and morphological changes.

Developing a biorefinery process for a highly integrated valorization and fractionation of lignocellulose is crucial for its utilization. Herein, a biphasic system comprising choline chloride/lactic acid and 2-methyltetrahydrofuran with Al2(SO4)3 and H2SO4 as catalysts was applied to pretreat Eucalyptus. Results showed that under the optimized conditions (150 °C, 30 min, 0.2 M Al2(SO4)3, 0.075 M H2SO4), the furfural yield and enzymatic hydrolysis efficiency could reach 54.7% and 97.0%, respectively. The efficient cellulose conversion was attributed to remarkable removal of lignin (91.0%) and hemicelluloses (100.0%), thereby causing the disruption of cell wall structure and enhancement of cellulose accessibility. Meanwhile, confocal Raman microscope and atomic force microscope displayed that the pretreatment resulted in the decreasing intensities of carbohydrates and lignin different regions of cell walls, and exposing of the embedded microfibers from noncellulosic polymers. Overall, the deep eutectic solvent-based biphasic system displayed high performance for effective utilization of carbohydrate components in lignocellulose.

Transcranial direct current stimulation modulates the brain's response to foot stimuli under dual-task condition: A fMRI study in elderly adults.

Previous behavioral studies have shown that high-intensity cognitive tasks weaken balance control in elder adults. Moreover, age-related loss of plantar sensation is considered to be an important contributing factor to the occurrence of falls. Recently, we have realized that transcranial direct current stimulation (tDCS) can effectively improve the balance of the elderly under the dual-task, but its underlying regulatory mechanism is not clear. In this study, task functional Magnetic Resonance Imaging (fMRI) was used to study the brain's response to foot stimuli under foot stimuli or dual-task (foot stimuli and cognitive task) conditions to explain the effect of the addition of cognitive tasks during balance in 16 healthy elderly adults. To study whether tDCS would counteract the effect of the added cognitive task, we further compared the differences in activity of the cerebral cortices of dual-task and tDCS-dual-task conditions. The results suggested added cognitive tasks significantly attenuated the response of the brain to foot stimuli in elderly adults. Moreover, the cortex excitability weakened by cognitive tasks was significantly promoted after 20 min of tDCS. In conclusion, a portion of the resources originally used for plantar sensory processing may be assigned to the processing of the cognitive task when the cognitive tasks are added, which results in insufficient resources for plantar sensory processing. tDCS improves the ability of the brain to respond to foot stimuli by modulating the excitability of the cognitive cortex and reverses the effects of cognitive tasks.

Aquabis-(6-bromo-picolinato-κN,O)copper(II).

In the title compound, [Cu(C(6)H(3)BrNO(2))(2)(H(2)O)], the Cu atom adopts a distorted trigonal-bipyramidal coordination arising from two N,O-bidentate ligands and a water mol-ecule, with one N atom in an axial site and the other in an equatorial site. The dihedral angle between the pyridine ring planes is 67.6 (2)°. In the crystal, O-H⋯O hydrogen bonds result in chains propagating in [100].