Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202507111
This study investigated the effects of a ring-shaped pulsed electric field (PEF) (1.5 V, 4 h on-time per cycle) on nitrogen removal performance and microbial community structure of anammox granular sludge (AnGS). Two anaerobic sequencing batch reactors (R1 control, R2 with PEF) were operated under stepwise increasing nitrogen loading rates (NLR). At NLR below 1,155 mg·(L·d)−1, R2 exhibited total nitrogen removal efficiency (TRE) 7.5%–17.0% higher than R1, with biomass, specific anammox activity (SAA), and extracellular polymeric substances (EPS) increased by 5%–7%, 21%–71%, and 54%–77%, respectively. However, at NLR above 1,320 mg·(L·d)−1, the toxic effect of nitrite dominated, and PEF enhancement diminished or even reversed to inhibition. Microbial community analysis revealed that at low-to-moderate NLR, PEF increased the relative abundance of Planctomycetes and key anammox bacteria (Candidatus Brocadia and Candidatus Jettenia), along with enhanced community richness (Chao1) and diversity (Shannon/Simpson indices). At high NLR, PEF decreased microbial richness compared to R1. Principal component analysis and redundancy analysis indicated that PEF was the key factor driving community differences at low-to-moderate NLR, whereas nitrite concentration became the dominant factor at high NLR. This study provides theoretical support for enhancing the resilience and engineering application of anammox processes.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3804-7
Supramolecular helical architectures hold promise for enantioselective catalysis, yet the influence of screw pitch on catalytic performance remains underexplored. Here, we report the construction of right-/left-handed helical nanoribbons (P/M-DAIPA) based on 5-aminoisophthalic acid dimer (DAIPA). Through an alcohol-mediated self-assembly strategy, the average screw pitch was tuned from 360 to 3152 nm. Mechanistic studies revealed that hydrogen-bonding interactions between DAIPA, modulated by alcohol identity and alcohol/water ratios, dictate helical morphology and pitch. Encapsulation of Fe3O4 nanoparticles yielded P-DAIPA-Fe3O4 and M-DAIPA-Fe3O4 nanozymes, which exhibited higher catalytic efficiency toward S-3,4-dihydroxyphenylalanine (DOPA) and R-DOPA, respectively. Notably, catalytic enantioselectivity inversely correlated with screw pitch, achieving selectivity factors from 1.52 to 2.01. Experimental evidence demonstrated that shorter screw pitch enhances adsorption enantioselectivity of R/S-DOPA on the nanozymes, providing mechanistic insight into pitch-dependent asymmetric catalysis. This work deciphers solvent-driven control of supramolecular screw pitch and establishes a framework for engineering chiral nanozymes with tunable enantioselectivity, advancing enantioselective synthesis.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4040-0
High-performance organic second-order nonlinear optical (NLO) crystals face a persistent challenge: molecular designs that enhance hyperpolarizability often crystallize into centrosymmetric or nonpolar arrangements, suppressing bulk second-order response, while simultaneously reducing optical bandgaps, enforcing a trade-off between nonlinearity and transparency. We report a chirality-driven polar lattice engineering strategy that couples molecular asymmetry with directional intermolecular interactions to promote polar ordering. A binaphthyl-based chromophore (S-3) crystallizes in the polar space group P2₁, exhibiting strong second-harmonic generation (~3.53 × KDP), wide transparency (3.91 eV), phase-matchable birefringence (Δn = 0.15), high laser damage threshold (742.6 MW cm⁻²), and thermal stability up to 210 °C. Theoretical calculations reveal a 69% enhancement in first-order hyperpolarizability (β_tot) relative to the unfunctionalized derivative, with a net intramolecular electron transfer of 0.16 e⁻ from the chiral scaffold to the benzoate acceptor. Crucially, enantiomeric crystals exhibit identical NLO responses, confirming that bulk nonlinearity is governed by engineered lattice polarity, not molecular handedness. This work establishes chirality as an active tool for crystal engineering and provides a general design paradigm for high-performance organic NLO materials.