Ensemble learning algorithms to elucidate the core microbiome's impact on carbon content and degradation properties at the soil aggregate level.

Soil aggregates are crucial for soil organic carbon (OC) accumulation. This study, utilizing a 32-year fertilization experiment, investigates whether the core microbiome can elucidate variations in carbon content and decomposition across different aggregate sizes more effectively than broader bacterial and fungal community analyses. Employing ensemble learning algorithms that integrate machine learning with network inference, we found that the core microbiome accounts for an average increase of 26 % and 20 % in the explained variance of PCoA and Adonis analyses, respectively, in response to fertilization. Compared to the control, inorganic and organic fertilizers decreased the decomposition index (DDI) by 31 % and 38 %, respectively. The fungal core microbiome predominantly influenced OC content and DDI in larger macroaggregates (>2000 µm), explaining over 35 % of the variance, while the bacterial core microbiome had a lesser impact, explaining <30 %. Conversely, in smaller aggregates (<2000 µm), the bacterial core microbiome significantly influenced DDI (R2 > 0.2), and the fungal core microbiome more strongly affected OC content (R2 > 0.3). Mantel tests showed that pH is the most significant environmental factor affecting core microbiome composition across all aggregate sizes (Mantel's r > 0.8, P < 0.01). Linear correlation analysis further confirmed that the core microbiome's community structure could accurately predict OC content and DDI in aggregates (R2 > 0.8, P < 0.05). Overall, our findings suggested that the core microbiome provides deeper insights into the variability of aggregate organic carbon content and decomposition, with the bacterial core microbiome playing a particularly pivotal role within the soil aggregates.

Ultrasensitive Screening of Endocrine-Disrupting Chemicals Using a Surface Plasmon Resonance Biosensor with Polarization-Compensated Laser Heterodyne Feedback.

Developing an ultrasensitive and reliable device for continuous monitoring of various endocrine-disrupting chemicals (EDCs) is in high demand, yet it remains a significant challenge. Traditional label-free surface plasmon resonance (SPR) sensing relies on the interaction of the surface plasmon wave and the sensing liquid via intensity modulation, endowed with simple structure and easy-to-miniaturization, however suffering from inferior sensitivity and stability. Here, we propose a novel optical structure in which the frequency-shifted light of different polarization returned to the laser cavity to stimulate laser heterodyne feedback interferometry (LHFI), hence amplifying the reflectivity change caused by the refractive index (RI) variations on the gold-coated SPR chip surface, and the s-polarized light could be further used as a reference to compensate for the noise of the LHFI-amplified SPR system, resulting in nearly three orders of magnitude enhancement of the RI sensing resolution (5.9 × 10-8 RIU) compared to the original SPR system (2.0 × 10-5 RIU). To further boost intense signal enhancement, custom-designed gold nanorods (AuNRs), which were optimized by the finite-difference time-domain (FDTD) simulation, were used to generate localized surface plasmon resonance (LSPR). By exploiting the estrogen receptor as the recognition material, estrogenic active chemicals were detected with a 17ß-estradiol/L detection limit of 0.004 ng, which is nearly 180-fold lower than that of the system without introducing AuNRs. The developed SPR biosensor is expected to be capable of screening various EDCs with universality by using several nuclear receptors, such as the androgen receptor and thyroid receptor, and will substantially accelerate the assessment of global EDCs.

An Ultrasensitive and Universal Surface Plasmonic Biosensor for Detection of Micropollutants in Aquatic Environments.

Simple yet ultrasensitive and accurate quantification of a variety of analytical targets by virtue of a universal sensing device holds promise to revolutionize environmental monitoring, medical diagnostics, and food safety. Here, we propose a novel optical surface plasmon resonance (SPR) system in which the frequency-shifted light of different polarizations returned the laser cavity to stimulate laser heterodyne feedback interferometry (LHFI), hence amplifying the reflectivity change caused by the refractive index (RI) variations on the gold-coated SPR chip surface. In addition, the s-polarized light was further used as the reference to compensate the noise of the LHFI-amplified SPR system, resulting in nearly 3 orders of magnitude enhancement of RI resolution (5.9 × 10-8 RIU) over the original SPR system (2.0 × 10-5 RIU). By exploiting nucleic acids, antibodies, and receptors as recognition materials, a variety of micropollutants were detected with ultralow detection limits, ranging from a toxic metal ion (Hg2+, 70 ng/L) to a group of commonly occurring biotoxin (microcystins, 3.9 ng microcystin-LR/L) and a class of environmental endocrine disruptors (estrogens, 0.7 ng 17ß-estradiol/L). This sensing platform exhibits several distinct characteristics, including dual improvement of sensitivity and stability and common-path optical construction without needing optical alignment, demonstrating a promising avenue toward environmental monitoring.

Surface plasmon resonance biosensor with laser heterodyne feedback for highly-sensitive and rapid detection of COVID-19 spike antigen.

The ongoing outbreak of the COVID-19 has highlighted the importance of the pandemic prevention and control. A rapid and sensitive antigen assay is crucial in diagnosing and curbing pandemic. Here, we report a novel surface plasmon resonance biosensor based on laser heterodyne feedback interferometry for the detection of SARS-CoV-2 spike antigen, which is achieved by detecting the tiny difference in refractive index between different antigen concentrations. The biosensor converts the refractive index changes at the sensing unit into the intensity changes of light through surface plasmon resonance, achieving label-free and real-time detection of biological samples. Moreover, the gain amplification effect of the laser heterodyne feedback interferometry further improved the sensitivity of this biosensor. The biosensor can rapidly respond to continuous and periodic changes in the refractive index with a high resolution of 3.75 × 10-8 RIU, demonstrating the repeatability of the biosensor. Afterwards, the biosensor is immobilized by the anti-SARS-CoV-2 spike monoclonal antibodies, thus realizing the specific recognition of the antigen. The biosensor exhibited a high sensitivity towards the concentration of the antigen with a linear dynamic range of five orders of magnitude and a resolution of 0.08 pg/mL. These results indicate that this principle can be used as a rapid diagnostic method for COVID-19 antigens without sample labelling.

Facile ammonium oxidation to nitrogen gas in acid wastewater by in situ photogenerated chlorine radicals.

The treatment of low-concentration ammonium (e.g., <50 mg L-1) in highly acidic wastewaters through traditional biological nitrification, physical separation, or chemical stripping remains a huge challenge. Herein, we report that photocatalytic ammonium oxidation using bismuth oxychloride (BiOCl) can successfully occur in Cl--laden solutions within a pH range of 1.0-6.0. All reactions follow pseudo-zero-order kinetics (with rate constants of 0.27-0.32 mg L-1 min-1 at pH 2.0-6.0 and 0.14 mg L-1 min-1 at pH 1.0), indicating the saturation of reactive species by the reactants. The interlayer is self-oxidized by the valence band holes (VB h+), resulting in the formation of Cl• and subsequently HClO, which is excited upon UV irradiation to provoke consecutive photoreactions for chlorine radical generation. Compared to the free chlorine, HO•, Cl•, and Cl2•-, the ClO• produced using the UV/BiOCl system plays a predominant role in oxidizing ammonium under acidic conditions. BiOCl exhibits good stability because of the compensation of Cl- from solution and maintains high activity under different conditions (i.e., different cations and co-existing anions, temperatures, and initial substrate concentrations). The successful removal of ammonium from real wastewater using the UV/BiOCl system suggests that this is a promising method for treating diluted ammonium under highly acidic conditions.