Poly(vinyl alcohol)/sodium alginate polymer membranes as eco-friendly and biodegradable coatings for slow release fertilizers.

BACKGROUND: The use of slow release fertilizers (SRFs) is an effective approach for reducing agriculture cost, environmental and ecological issues simultaneously. The present study provides a series of poly(vinyl alcohol) (PVA)/sodium alginate (SA) polymer membranes as eco-friendly and biodegradable coatings for SRFs. Moreover, polymer-coated urea (PCU) granules were fabricated through coating the urea granules with the resulting membranes. Our first interest was to fabricate three membranes (PS1, PS2, PS3) of different PVA/SA weight ratios (9:1, 8:2, 7:3) using glutaraldehyde as a crosslinking agent, and crosslink the PS3 membrane with a CaCl2 solution further to obtain the PC3 membrane. The chemical properties and morphologies of the membranes were characterized. Second, the nitrogen release behavior of the PCU granules was measured and calculated, respectively. RESULTS: Crosslinking with glutaraldehyde made the PS1, PS2, PS3 membranes uniform and compact, whereas crosslinking with a CaCl2 solution formed an 'egg box' structure inside the PC3 membrane. PS3 membrane with the minimum PVA/SA weight ratio had the highest hydrophily (water uptake: 106.25%, water contact angle: 55.1o ), whereas PC3 membrane had the lowest hydrophily (water uptake: 21.57%, water contact angle: 67.3o ). The biodegradation ratios of the membranes were in the range 44-60% in 90 days, indicating that they had excellent biodegradability. The measured fractional release on the day 30 of the PCU granules ranged from 89.33% to 97.07%. The calculated nitrogen release behavior agreed well with the measured values. CONCLUSION: The resulting eco-friendly and biodegradable PVA/SA membranes are alternative coatings for SRFs. © 2022 Society of Chemical Industry.

Highly Tough, Stretchable, and Solvent-Resistant Cellulose Nanocrystal Photonic Films for Mechanochromism and Actuator Properties.

Cellulose nanocrystals (CNCs)-derived photonic materials have confirmed great potential in producing renewable optical and engineering areas. However, it remains challenging to simultaneously possess toughness, strength, and multiple responses for developing high-performance sensors, intelligent coatings, flexible textiles, and multifunctional devices. Herein, the authors report a facile and robust strategy that poly(ethylene glycol) dimethacrylate (PEGDMA) can be converged into the chiral nematic structure of CNCs by ultraviolet-triggered free radical polymerization in an N,N-dimethylformamide solvent system. The resulting CNC-poly(PEGDMA) composite exhibits impressive strength (42 MPa), stretchability (104%), toughness (31 MJ m-3 ), and solvent resistance. Notably, it preserves vivid optical iridescence, displaying stretchable variation from red, yellow, to green responding to the applied mechanical stimuli. More interestingly, upon exposure to spraying moisture, it executes sensitive actuation (4.6° s-1 ) and multiple complex 3D deformation behaviors, accompanied by synergistic iridescent appearances. Due to its structural anisotropy of CNC with typical left-handedness, the actuation shows the capability to generate a high probability (63%) of right-handed helical shapes, mimicking a coiled tendril. The authors envision that this versatile system with sustainability, robustness, mechanochromism, and specific actuating ability will open a sustainable avenue in mechanical sensors, stretchable optics, intelligent actuators, and soft robots.

A Novel Anion Exchange Membrane for Bisulfite Anion Separation by Grafting a Quaternized Moiety through BPPO via Thermal-Induced Phase Separation.

Ion-exchange membranes are the core elements for an electrodialysis (ED) separation process. Phase inversion is an effective method, particularly for commercial membrane production. It introduces two different mechanisms, i.e., thermal induced phase separation (TIPS) and diffusion induced phase separation (DIPS). In this study, anion exchange membranes (AEMs) were prepared by grafting a quaternized moiety (QM,2-[dimethylaminomethyl]naphthalen-1-ol) through brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO) via the TIPS method. Those membranes were applied for selective bisulfite (HSO3-) anion separation using ED. The membrane surface morphology was characterized by SEM, and the compositions were magnified using a high-resolution transmission electron microscope (HRTEM). Notably, the membranes showed excellent substance stability in an alkali medium and in grafting tests performed in a QM-soluble solvent. The ED experiment indicated that the as-prepared membrane exhibited better HSO3- separation performance than the state-of-the-art commercial Neosepta AMX (ASTOM, Japan) membrane.

Bioinspired Interfacial Materials with Enhanced Drop Mobility: From Fundamentals to Multifunctional Applications.

The development of bioinspired interfacial materials with enhanced drop mobility that mimic the innate functionalities of nature will have a significant impact on the energy, environment and global healthcare. Despite extensive progress, state of the art interfacial materials have not reached the level of maturity sufficient for industrial applications in terms of scalability, stability, and reliability. These are complicated by their operating environments and lack of facile approaches to control the local structural texture and chemical composition at multiple length scales. The recent advances in the fundamental understanding are reviewed, as well as practical applications of bioinspired interfacial materials, with an emphasis on the drop bouncing and coalescence-induced jumping behaviors. Perspectives on how to catalyze new discoveries and to foster technological adoption to move this exciting area forward are also suggested.

Discovery of antifungal constituents from the Miao medicinal plant Isodon flavidus.

ETHNOPHARMACOLOGICAL RELEVANCE: Leigong Mountain is an area in the Southwest of China where there is a high incidence rate of athlete's foot, but the Miao people, a Chinese minority who reside in this mountainous area have suffered less from this disease due to their use of the herbal medicine Isodon flavidus (Hand.-Mazz.) H. Hara. AIM OF THE STUDY: The present study is to identify the active chemical constituents responsible for antifungal effects of the folk medicine plant. MATERIALS AND METHODS: The natural compounds were separated from the methanol extract of the twigs and leaves of I. flavidus by phytochemical study using chromatographic methods, and their chemical structures were determined by analysis of the spectroscopic data including 1D and 2D NMR spectra. The absolute configuration of fladin A (1) was further confirmed by X-ray crystallographic analysis. The compounds were evaluated for their antifungal activity against the athlete's foot fungus Trichophyton rubrum. They were further evaluated for their antimicrobial and anti-biofilm activity against the dental pathogens Streptococcus mutans, Porphyromonas gingivalis and Candida albicans. RESULTS: Phytochemical and biological studies of I. flavidus led to the discovery of two antifungal compounds, fladin A (1) and lophanic acid (2). Fladin A (1) is a novel diterpene with an unprecedented cyclic ether group formed between C-4 and C-9. Lophanic acid (2) displayed inhibition activity against the athlete's foot fungus Trichophyton rubrum with an MIC value of 7.8µg/mL, and fladin A (1) also showed inhibition activity against the fungus with a MIC value of 62.5µg/mL. CONCLUSIONS: Our identification of two antifungal compounds provided strong evidence for the Miao people to use I. flavidus as a medicinal plant for treatment of athlete's foot disease. The very different chemical structures of the active compounds from those in the market presents them as potential antifungal lead compounds for follow-up study.

Synthesis of 8-desbromohinckdentine A1.

Hinckdentine A is an alkaloid isolated from the bryozoan Hincksinoflustra denticulate. This natural product contains a novel and unique 11b,12,13,14,15,16-hexahydroazepino[4',5':2,3]indolo[1,2-c]quinazoline ring system that has not previously been synthesized. We have synthesized 8-desbromohinckdentine A from a 2-aryl indole by first preparing the quaternary center of the natural product and then building the seven-membered lactam and dihydropyrimidine rings onto this intermediate to form the framework of hinckdentine A.