Shimane University

Biochar is increasingly being explored for soilless cultivation; however, high pH, elevated electrical conductivity (EC), and heterogeneous particle size often limit its use as a standalone growing medium. This study evaluated peanut shell biochar (PS-BC) as the sole substrate for Komatsuna ( Brassica rapa var. perviridis ) and assessed its short-term reuse across two consecutive crop cycles. Pot experiments examined the effects of particle size and PS-BC conditioning (unwashed vs. prewashed), rinsing frequency and reuse, and acid treatments using pyroligneous acids (PAs) and citric acid (CA). Prewashing markedly improved plant growth, and leaf area and dry weight increased by up to approximately four-fold across particle sizes; however, pH and EC decreased by approximately 7% and 89%, respectively. Changes in substrate chemical properties were also observed. Particle size had a lesser effect on plant performance, with the greatest response observed for particle sizes of 5 mm and >7 mm. Interestingly, the rinsing frequency did not significantly affect plant height or dry weight within individual crop cycles; however, reuse of the preconditioned PS-BC was associated with improved plant height and leaf area as well as further shifts in substrate chemical and nutrient statuses relative to the original unwashed substrate. Both PA and CA treatments reduced pH dose-dependently, but only PA treatments increased EC. The best plant performance was observed with 5% CA and 14% rice-derived PA, whereas bamboo PA inhibited growth despite acceptable pH levels. Overall, preconditioned PS-BC effectively supported Komatsuna growth and maintained performance upon reuse across two consecutive crop cycles, demonstrating its potential as a practical standalone substrate for short-term leafy vegetable production.

Charge-transfer (CT) type π-conjugated polymers (CPs) comprising donor and acceptor aromatic units offer tunable optical and electrochemical properties, which are important for electronic and photonic applications. In this study, we synthesized CT-type polyphenylenes, P(Flu-BQ) and P(Ph-BQ), containing 9,9-dihexylfluorene or 1,4-dihexyloxybenzene as donor units and benzoquinone (BQ) as an acceptor. Reduction of BQ to hydroquinone (HQ) allowed systematic investigation of CT effects by comparison of optical and electrochemical properties before and after reduction. Polymers composed of BQ and HQ units, P(BQ-HQ), were also prepared via sulfuric acid-mediated polymerization, and their composition ratios were controlled by varying acid concentration. Subsequent reactions of HQ units yielded acetylated polymers, P(BQ-AcQ), and TCNQ-substituted polymers, P(TCNQ-AcQ), to modulate CT characteristics. UV–vis absorption, photoluminescence, fluorescence lifetime, and cyclic voltammetry studies revealed that CT along the polymer backbone strongly influences emission behavior and redox properties. Specifically, reduction of BQ suppressed intramolecular CT (ICT), leading to enhanced fluorescence in P(Flu-BQ) and P(Ph-BQ), while incorporation of TCNQ units enhanced CT in P(TCNQ-AcQ), as confirmed by formation of a 1:1 CT complex with 2,6-dimethyltetrathiafulvalene (DM-TTF). These results provide a clear relationship between CT and the optical/electrochemical properties of CPs, highlighting strategies to tune polymer functionality via donor–acceptor design.

In order to develop molecular magnetic compounds, oligonuclear cobalt complexes with Schiff-base ligands, 1,3-bis(salicylideneamino)-2-propanol (H3salpr), 1,3-bis(5-chlorosalicylideneamino)-2-propanol (H3clsalpr), 1,3-bis(5-bromosalicylideneamino)-2-propanol (H3brsalpr), and 1,3-bis(5-nitrosalicylideneamino)-2-propanol (H3pnsalpr), were synthesized by reaction of cobalt(II) acetate and Schiff-base ligand in organic solvent. The molecular structures of [CoII{CoIII(µ-HL)(µ-CH3COO)(CH3COO)}2] (HL = Hsalpr and Hbrsalpr), [CoII{CoII(µ-Hsalpr)(µ-CH3COO)}2], and [CoIII2CoII4(µ-L)2(µ3-CH3O)2(µ-CH3O)6(CH3OH)2] (L = salpr, clsalpr, brsalpr, and pnsalpr) were elucidated by the single-crystal X-ray crystallography. The electronic spectra and magnetic susceptibilities with variable-temperature are in accordance with the trinuclear and hexanuclear molecular structures. The cyclic voltammograms are basically featureless, giving a clue to isolate reduced complexes [CoII{CoII(µ-Hsalpr)(µ-CH3COO)}2] and [CoII2(Hpnsalpr)2(CH3OH)]. These findings may guide future design of molecular magnet materials.