Hydroxyl radicals-mediated oxidative cleavage of the glycosidic bond in cellobiose by copper catalysts and its application to low-temperature depolymerization of cellulose

A review of the fungal polysaccharides as natural biopolymers: Current applications and future perspective

As a unique natural resource, fungi are a sustainable source of lipids, polysaccharides, vitamins, proteins, and other nutrients. As a result, they have beneficial medicinal and nutritional properties. Polysaccharides are among the most significant bioactive components found in fungi. Increasing research has revealed that fungal polysaccharides (FPS) contain a variety of bioactivities, including antitumor, antioxidant, immunomodulatory, anti-inflammatory, hepatoprotective, cardioprotective, and anti-aging properties. However, the exact knowledge about FPS and their applications related to their future possibilities must be thoroughly examined to enhance a better understanding of this sustainable biopolymer source. Therefore, FPS' biological applications and their role in the food and feed industry, agriculture, and cosmetics applications were all discussed in this work. In addition, this review highlighted the mode of action of FPS on human diseases by regulating gut microbiota and discussed the mechanism of FPS as antioxidants in the living cell. The structure-activity connections of FPS were also highlighted and explored. Moreover, future perspectives were listed to pave the way for future studies of FPS applications. Hence, this study can be a scientific foundation for future FPS research and industrial applications.

Aerobic Oxidative Cleavage of C(OH)-C Bonds to Produce Aromatic Aldehydes Catalyzed by CuI -1,10-phenanthroline Complex

Effective cleavage and functionalization of C(OH)-C bonds is of great importance for the production of value-added chemicals from renewable biomass resources such as carbohydrates, lignin and their derivatives. The efficiency and selectivity of oxidative cleavage of C(OH)-C bonds are hindered by their inert nature and various side reactions associated with the hydroxyl group. The oxidative conversion of secondary alcohols to produce aldehydes is particularly challenging because the generated aldehydes tend to be over-oxidized to acids or the other side products. Noble-metal based catalysts are necessary to get satisfactory aldehyde yields. Herein, for the first time, the efficient aerobic oxidative conversion of secondary aromatic alcohols into aromatic aldehydes is reported using non-noble metal catalysts and environmentally benign oxygen, without any additional base. It was found that CuI -1,10-phenanthroline (Cu-phen) complex showed outstanding performance for the reactions. The C(OH)-C bonds of a diverse array of aromatic secondary alcohols were effectively cleaved and functionalized, selectively affording aldehydes with excellent yields. Detailed mechanism study revealed a radical mediated pathway for the oxidative reaction. We believe that the findings in this work will lead to many explorations in non-noble metal catalyzed oxidative reactions.

Rice husk-intensified cathode driving bioelectrochemical reactor for remediating nitrate-contaminated groundwater

To achieve economical and eco-friendly denitrification, rice husk-intensified cathode driving bioelectrochemical reactor (RCBER) was constructed with rice husk as solid-phase carbon source and microbial carrier. Results demonstrated that the application of current improved the utilization of rice husk and enhanced the denitrification, and the quenching of anodic hydroxyl radicals by rice husk also improved the microbial resistance to current. The highest nitrate removal rate as 0.34 mg-N/(L∙d), higher economic benefits, i.e., current efficiency as 31.6% and energy consumption as 2.43 kWh/g NO₃^--N, and the highest environmental benefit, i.e., hydrogenotrophic denitrification contribution as 37.9%, were obtained at 200 mA/m². The best performance at 200 mA/m² was related to its better microenvironment, such as lower accumulation of anodic by-products and higher bioavailability of rice husks, as well as higher microbial metabolic activity, such as stable extracellular polymeric substance, the maximum electron transport system activity as 11.63 ± 0.14 μg O₂·g^-1·min^-1·mg protein^-1 and the highest activity of nitrate reductase (3.15-fold that of control check). The application of current realized the coexistence of heterotrophic and hydrogenotrophic denitrifiers, and multiple functional bacteria such as anaerobic denitrifiers Flavobacterium, aerobic denitrifiers Comamonas, hydrogenotrophic denitrifiers Thermomonas and electron transfer-related Enterobacter coexisted at 200 mA/m², thereby improving RCBER's adaptability to the complex microenvironment. This study provides the theoretical basis for realizing a win-win situation of environmental pollution remediation and agricultural waste disposal.

Cavitation Fibrillation of Cellulose Fiber

Cellulose fibrils are the structural backbone of plants and, if carefully liberated from biomass, a promising building block for a bio-based society. The mechanism of the mechanical release─fibrillation─is not yet understood, which hinders efficient production with the required reliable quality. One promising process for fine fibrillation and total fibrillation of cellulose is cavitation. In this study, we investigate the cavitation treatment of dissolving, enzymatically pretreated, and derivatized (TEMPO oxidized and carboxymethylated) cellulose fiber pulp by hydrodynamic and acoustic (i.e., sonication) cavitation. The derivatized fibers exhibited significant damage from the cavitation treatment, and sonication efficiently fibrillated the fibers into nanocellulose with an elementary fibril thickness. The breakage of cellulose fibers and fibrils depends on the number of cavitation treatment events. In assessing the damage to the fiber, we presume that microstreaming in the vicinity of imploding cavities breaks the fiber into fibrils, most likely by bending. A simple model showed the correlation between the fibrillation of the carboxymethylated cellulose (CMCe) fibers, the sonication power and time, and the relative size of the active zone below the sonication horn.