Beneath the surface: Decoding the impact of Chironomus riparius bioturbation on microplastic dispersion in sedimentary matrix

A detailed understanding of microplastics (MPs) behaviour in freshwater ecosystems is crucial for a proper ecological assessment. This includes the identification of significant transport pathways and net accumulation zones, considering their inherent, and already proven influence on aquatic ecosystems. Bioavailability of toxic agents is significantly influenced by macroinvertebrates' behaviour, such as bioturbation and burrowing, and their prior exposure history. This study investigates the effect of bioturbation activity of Chironomus riparius Meigen, 1804 on the vertical transfer of polyethylene MPs ex-situ. The experimental setup exposes larvae to a scenario of 10× the environmentally relevant high concentration of MPs (80 g m-2). Bioturbation activity was estimated using sediment profile imaging with luminophore tracers. This study demonstrated that spherical MPs are vertically transferred in the sediment due to the bioturbation activity of C. riparius larvae and that their presence influences the intensity of the bioturbation activity over time. The present findings provide a noteworthy contribution to the understanding of the relationship between ecosystem engineers and the dispersion and accumulation of MPs within freshwater ecosystems.

Excitation Wavelength-Dependent Fluorescence of a Lanthanide Organic Metal Halide Cluster for Anti-Counterfeiting Applications

The achievement of significant photoluminescence (PL) in lanthanide ions (Ln3+ ) has primarily relied on host sensitization, where energy is transferred from the excited host material to the Ln3+ ions. However, this luminous mechanism involves only one optical antenna, namely the host material, which limits the accessibility of excitation wavelength-dependent (Ex-De) PL. Consequently, the wider application of Ln3+ ions in light-emitting devices is hindered. In this study, we present an organic-inorganic compound, (DMA)4 LnCl7 (DMA+ =[CH3 NH2 CH3 ]+ , Ln3+ =Ce3+ , Tb3+ ), which serves as an independent host lattice material for efficient Ex-De emission by doping it with trivalent antimony (Sb3+ ). The pristine (DMA)4 LnCl7 compounds exhibit high luminescence, maintaining the characteristic sharp emission bands of Ln3+ and demonstrating a high PL quantum yield of 90-100 %. Upon Sb3+ doping, the compound exhibits noticeable Ex-De emission with switchable colors. Through a detailed spectral study, we observe that the prominent energy transfer process observed in traditional host-sensitized systems is absent in these materials. Instead, they exhibit two independent emission centers from Ln3+ and Sb3+ , each displaying distinct features in luminous color and radiative lifetime. These findings open up new possibilities for designing Ex-De emitters based on Ln3+ ions.

Graphdiyne: A New Carbon Allotrope for Electrochemiluminescence

Graphdiyne (GDY), a well-known 2D carbon allotrope, demonstrates increasing fantastic performance in various fields owing to its outstanding electronic properties. Owing to its unique properties, electrochemiluminescence (ECL) technology is one powerful tool for understanding fundamental questions and for ultrasensitive sensing and imaging. Here, we firstly find that GDY without any functionalization or treatment shows a strong ECL emission with potassium persulfate (K₂ S₂ O₈ ) as coreactant, which is totally different with other carbon allotropes. Mechanistic study indicates that the ECL emission of GDY is generated by the surface state transition. Interestingly, ECL is generated at 705 nm in the near infrared region with an ECL efficiency of 424 % compared to that of Ru(bpy)₃ Cl₂ /K₂ S₂ O₈ . The study demonstrates a new character of GDY in ECL investigation and sets the stage for the development of GDY for emerging applications, including imaging and light-emitting devices.

Bridged Aromatic Oxo- and Thioethers with Intense Emission in Solution and the Solid State

In this contribution, we report on a class of emitters based on bridged oxo- and/or thioethers revealing striking photoluminescence properties in fluid solution and in the solid state. In total, nine compounds were investigated concerning their photophysical properties, which were interpreted by quantum chemical calculations. To our delight, we discovered compounds possessing nearly identical photoluminescence quantum yields (Φ_F ) in solution and in the solid state, which has been rarely reported so far. Besides these efforts, we shed light on the influence of polymorphism and solvent polarity on the emission properties. In addition, an in-depth X-ray diffractometric analysis was conducted to correlate molecular packing in the crystal with differences in the photophysical properties.

Recent advances in electrochemiluminescence luminophores

Electrochemiluminescence (ECL) has continued to receive considerable attention in various applications, owing to its intrinsic advantages such as near-zero background response, wide dynamic range, high sensitivity, simple instrumentation, and low cost. The ECL luminophore is one of the most significant components during the light generation processes. Despite significant progress that has been made in the synthesis of new luminophores and their roles in resolving various challenges, there are few comprehensive summaries on ECL luminophores. In this review, we discuss some of the recent advances in organic, metal complexes, nanomaterials, metal oxides, and near-infrared ECL luminophores. We also emphasize their roles in tackling various challenges with illustrative examples that have been reported in the last few years. Finally, perspective and some unresolved challenges in ECL that can potentially be addressed by introducing new luminophores have also been discussed. Graphical abstract.

Spectroscopic and quantum chemical study of difluoroboron β-diketonate luminophores: Isomeric acetylnaphtholate chelates

The electronic structure and optical properties of the isomeric difluoroboron β-diketonates, 2,2-difluoro-4-methylnaphtho-[2,1-e]-1,3,2-dioxaborin (I) and 2,2-difluoro-4-methylnaphtho-[1,2-e]-1,3,2-dioxaborin (II), were studied by means of X-ray photoelectron, absorption and luminescence spectroscopies. The experimental results were interpreted using high-level ab initio quantum chemical computations, including the algebraic-diagrammatic construction method for the polarization propagator of the second and third orders (ADC(2) and ADC(3)), the outer-valence Green's function (OVGF) method, and the time-dependent density functional (TDDFT) approach. The X-ray photoelectron measurements were assigned in the entire energy range using the results of the Kohn-Sham orbital calculations which employed the B3LYP functional. Pronounced hypsochromic shift of crystal-state fluorescence was observed in I upon the lowering of temperature, which can be explained by the deterioration of the conditions for excimers formation. According to our results, remarkable feature of II, absent in I, is its phosphorescence at room temperature. Basing on our calculations, a decay mechanism for the S₁ state was proposed, explaining the observed differences in the phosphorescence of I and II.

Antimicrobial and photophysical properties of chemically grafted ultra-high-molecular-weight polyethylene

Surface of ultra-high-molecular-weight polyethylene (UHMWPE) was modified by chemical methods. Surface was firstly activated by Piranha solution and then grafted with selected amino-compounds (cysteamine, ethylenediamine or chitosan). The next step was grafting of some borane cluster compounds, highly fluorescent borane hydride cluster anti-B₁₈H₂₂ or its thiolated derivative 4,4'-(HS)₂-anti-B₁₈H₂₀. Polymer foils were studied using various methods to characterize surface chemistry (X-ray photoelectron spectroscopy), roughness and morphology (atomic force microscopy, scanning electron microscopy), chemistry and polarity (electrokinetic analysis), wettability (goniometry) and photophysical properties (UV-Vis spectroscopy) before and after modification steps. Subsequently some kinds of antimicrobial tests were performed. Immobilization of anti-B₁₈H₂₂ in small quantities onto UHMWPE surface leads to materials with a luminescence. Samples grafted with borane clusters showed significant inhibition of growth for gram-positive bacteria (S. epidermidis). These approaches can be used for (i) luminophores on the base of polymers nanocomposites development and/or (ii) preparation of materials with antimicrobial effects.

Size-selective feeding of Arenicola marina promotes long-term burial of microplastic particles in marine sediments

Despite of their ubiquitous distribution in marine sediments, the role of benthic fauna in microplastic transport at the sea floor has received little attention yet. The present study investigated the influence of bioturbation activity of the polychaete Arenicola marina on microplastic transport and burial in marine sediments. Sediment ingestion was assessed in a long term mesocosm experiment with exposure times ranging from 106 to 240 days, using three particle tracers with different particle diameters (microplastic: 500 and 1000 μm, respectively; luminophores: 130 μm). Sediment grain size distributions were assessed after experiment termination in all feeding layers at 8-12 cm depth to determine the influence of size-selective feeding of A. marina on median grain size and microplastic retention. Burial of microplastic occurred in all mesocosms up to a depth of 20 cm and was strongly dependent on individual sediment feeding rates. For low bioturbation conditions, both microplastic and luminophore concentrations exhibited an exponential decrease with increasing sediment depth, indicating particle burial via feeding funnel transport. Particle concentrations remained high in the uppermost 4 cm of the sediment. At high bioturbation rates, no microplastic particles remained in near-surface sediment layers, but a distinct accumulation of microplastic was observed in the feeding layer, suggesting the discrimination of plastic particles during feeding. In contrast, luminophores displayed a similar accumulation, but additionally showed uniform distributions above feeding layers, indicating ingestion and defecation by polychaetes. In accordance with these findings, an overall coarsening of median grain sizes was observed in all feeding layers, indicating the retention of large microplastic due to size-selective feeding. These findings demonstrate the ability of the conveyor belt-feeding polychaete A. marina to promote unidirectional transports of microplastic ≥500 μm and the potential for the long-term retention of these particles in marine sediments.

Pyridoxal 5'-phosphate assay based on lucigenin chemiluminescence

The authors describe the first chemiluminescence (CL) based method for determination of pyridoxal 5'-phosphate (PLP). PLP is found to generate intense CL with lucigenin higher than that of the conventional lucigenin-H₂O₂ system by a factor of about 9.0. This new finding is used to be in a detection method for PLP via flow injection analysis (FIA). Response is linear in the 50 nM to 200 μM PLP concentration range with a correlation coefficient of 0.998, and the detection limit (at an S/N of 3) is 6.9 nM. The assay is highly selective over various amino acids, vitamins, sugars, coenzymes and metal ions cofactors. It exhibits advantages over the commonly employed HPLC methods in that it is rapid, more economic, eco-friendly and high throughput FIA detection of PLP without the need for toxic derivatization reagents, organic solvents, and HPLC instrumentation. The method was successfully applied to the determination of PLP in (spiked) human blood samples with recoveries in the range from 96.2-101.6% with % RSD < 4.0. The new system is also employed to determine lucigenin in the linear range of 0.3 to 100.0 μM with a correlation coefficient of 0.994 and the limit of detection is 0.04 μM. Graphical abstract Schematic of the chemiluminescent assay for pyridoxal 5'-phosphate (PLP). Lucigenin-PLP demonstrates 9-fold stronger chemiluminescence intensity than the lucigenin-H₂O₂ system. The detection limit of PLP is 6.9 nM. The method can detect PLP in human serum with good recoveries.

Drilling discharges reduce sediment reworking of two benthic species

Effects of water-based drill cuttings on sediment reworking activity were studied on two important benthic bioturbators (the bivalve Abra segmentum and the brittle star Amphiura filiformis) using thin aquaria, fluorescent-dyed sediment particles (luminophores), time lapse photography and image analysis. In the present context, sediment reworking activity was measured as maximum mixing depth and total amount of luminophores transported below the sediment-water interface. There was a significant reduction in the amount of downward transported luminophores in drill cuttings treatments compared to controls with added natural sediments for both species, which also was true regarding maximum mixing depth for A. segmentum. Further, A. filiformis showed a clearly delayed burrowing of luminophores in the drill cuttings treatment compared to control. To conclude, the study showed that water-based drill cuttings have the potential to reduce sediment reworking. Further, it is evidenced that water-based drill cuttings not only cause burial effects.

X-Ray Induced and Thermostimulated Luminescence of New Fluorine Containing Compounds (Potential Luminophores, Scintillators and Dosimeters)

X-ray induced luminescence spectra in optical range of wave-lengths (200-700 nm) and thermoluminescence curves for fluoride, fluorosulphate, fluorophosphate and fluorooxalate compounds of the titanium subgroup elements with alkali metals and ammonium have been obtained. Influence of annealing and repeated X-raying on luminescence (XRL) spectra of a number of compounds has been examined. Alloy additives influence on fluorine compounds XRL spectra has been examined. Most of compounds being under study may be used as X-ray luminophores, scintillators and dosimeters. The highest intensity of luminescence was achieved for such compounds as K₂ZrF₆, Cs₂ZrF₆, Rb₂ZrF₆ (especially for doped K₂ZrF₆), K₂HfF₆ and CsZr₂(PO₄)₃. Radiation drifting to long-wave range for a number of fluorophosphatezirconates in comparison with fluorides may be a positive moment in making luminophores on their base.