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Development of an Electrochemical Sensing System for Simultaneous Detection of Species Relevant to Carbon Cycle in Seawater
No full textA portable electrochemical sensing system for simultaneous detection of species relevant to carbon cycle (i.e., Ca2+ , CO32- and pH) in seawater was developed, in which a highly sensitive polymeric membrane ionselective electrode array with NiCo2S4 -based transduction layer was used as the core element. Such an electrochemical sensor array was developed via the combination of all -solid -state ion selective electrode technology and electrode integration technology based on screen printing. The proposed sensing system offered the linear response concentration ranges of 1.0 x 10(-5) -1.0 x 10(-1) mol/L and 3.2 x 10(-5) -1.9 x 10(-3) mol/L for Ca2+ , CO32- and 5 -9 for pH in 0.5 mol/L NaCl background, respectively, as well as a relative deviation of less than 2.0 % for evaluation of detection accuracy (mean deviation compared to the readings of reference techniques). For successive measurements, the relative standard deviations (RSDs) of less than 2.5 % were obtained. The proposed electrochemical sensing system was successfully used for seawater analysis, and the whole analysis process could be completed within 15 min
The influences of Yellow River input and nutrient dynamics on colloidal Fe migration in the Bohai Sea, China
No full textThe coupling relationship between the <1 kDa, 1-3 kDa, 3-10 kDa, 10-100 kDa, and 100 kDa-0.45 mu m Fe fractions and the environmental factors in the Bohai Sea (BS) was investigated. The 1-100 kDa Fe in the surface water exhibited a non-conservative phenomenon during the river-sea mixing process, which was related to the removal of colloidal Fe via flocculation during this process. For the bottom water, the ligands released by the sediments may form additions to the <100 kDa Fe. The COC and DOC were mainly closely related to the behavior of the Fe in the bottom water. The <1 and 3-10 kDa Fe was mainly significantly positively correlated with the DOC, while the <100 kDa-0.45 mu m Fe was significantly negatively correlated with the DOC. <100 kDa LMW colloidal Fe exhibited more synergistic behavior with easily absorbed ammonium salts
Directional self-assembly of octavinyl polyhedral oligomeric silsesquioxane on the surface of melamine sponge: Establishing hydrophobic surfaces to improve oil-water separation performance
No full textThe continuous increase in industrial organic pollutants has seriously contaminated the natural environment, posing a threat to natural ecosystems and human survival. The preparation of hydrophobic materials with corrosion resistance is crucial for the efficient treatment of emulsified oil-water mixtures in industrial wastewater. Octavinyl polyhedral oligomeric silsesquioxane-coated melamine foam (OV-POSS@MF), possessing hydrophobic properties, was synthesized through a two-step process: initially, a sulfhydryl layer was built up on the surface of the melamine foam, followed by the subsequent assembly of octavinyl POSS onto the melamine foam's surface via a free radical polymerization reaction between sulfhydryl groups and vinyl moieties. OV-POSS@MF achieves a static water contact angle of 141 degrees, demonstrating its pronounced hydrophobic nature. Moreover, the corrosion resistance, adsorption capacity, oil-water separation efficiency, deformation resistance, and flame retardancy of OV-POSS@MF were thoroughly examined. The results indicate that OV-POSS@MF exhibits strong corrosion resistance and maintains good hydrophobicity even after prolonged exposure to highly acidic and alkaline conditions. Notably, OV-POSS@MF possesses the capability to efficiently and rapidly separate emulsified oil-water mixtures. Furthermore, it retains excellent hydrophobicity even after undergoing up to 100 consecutive compressions or distortions, highlighting its remarkable mechanical resilience. Additionally, OVPOSS@MF demonstrates superior flame retardant properties compared to unmodified melamine foam (MF)
Rapid Fingerprinting of Urinary Volatile Metabolites and Point-of-Care Diagnosis of Phenylketonuria on a Patterned Nanorod Sensor Array with Multiplexed Surface-Enhanced Raman Scattering Readouts
No full textPhenylketonuria (PKU) is one of the most common genetic metabolic diseases, especially among newborns. Traditional clinical examination of newborn blood samples for PKU is invasive, laborious, and limited to hospitals and healthcare facilities. We reported herein a SERS-based sensor array with three thiophenolic nanoreceptors built on a patterned nanorod vertical array for rapid and inexpensive detection of characteristic volatile biomarkers indicative of PKU in the urine and accurate classification of newborn baby patients all performed on a hand-held SERS spectrophotometer. The well-ordered array was generated from the volatility-driven assembly of gold nanorods (AuNRs) into an upright and closely packed hexagonal configuration. The uniformly distributed nanowells between AuNRs offered an intense and aspect-ratio-dependent plasmonic field for the molecular enhancement of SERS outputs. The SERS-based detector was integrated into a test chip for regular monitoring of volatile phenylketone bodies in the spiked solution or patients' urine within 5 min, allowing the quantification of a wide variety of normal or abnormal metabolites at their physiologically relevant concentration range. The detection limits for common biomarkers of PKU, including phenylpyruvic acid, 4-hydroxyphenylacetic acid, and phenylacetic acid, were at a few mu M and well below the diagnostic thresholds. Moreover, the volatile headspace mixtures from a given urine sample could be fingerprinted by the sensor array and discriminated using machine-learning algorithms. Ultimately, the discrimination of baby patients among 26 cases of mild and classic PKU phenotypes and 17 cases of healthy volunteers could be realized with an overall accuracy of 97%. This hand-held SERS platform plays a pivotal role in advancing healthcare applications in quick screening of neonatal PKU through a facile urinary vapor test
MGDA-assisted plant washing agent for improving the removal of Cd and Cu from farmland soils
No full textUtilizing plant extracts for soil washing is a promising and cost-efficient strategy to permanently remove toxic metals from farmland soils. However, the efficiency of current plant extracts in heavy metals removal is constrained by the need of excessively high liquid-solid ratios (>10:1), which limits their practical application in the farmland soils. To address this challenge, we developed a novel binary washing agent consisting of Fructus mume residue extract (RPM) and methylglycinediacetate acid (MGDA). Through optimization experiments, we determined an optimal composition of 50 g L-1 RPM and 0.34 g L-1 MGDA (RPMG3), which exhibited a remarkable synergistic effect on the removal of Cd and Cu from two polluted farmland soils. Compared to the single use of RPM or MGDA, RPMG3 increased metal removal efficiency by 44.6%-303.8% in the alkaline dryland soil and 55.8%-141.9% in the slightly acidic paddy soil, at an optimum liquid-solid ratio of 2:1. The contents of soil Cd and Cu can be reduced to below the risk screening values via acid activation, metal ion exchange, and complexation of functional groups. Moreover, the potential ecological risks associated with Cd in the soils were significantly mitigated due to the decrease in exchangeable and reducible Cd fractions following RPMG3 washing. Additionally, RPM and RPMG3 washing led to enhancements in soil organic carbon and nutrient concentrations, as well as increased activities of soil enzymes including catalase, urease, and beta-glucosidase. Notably, RPMG3 washing exhibited the most pronounced promotion effect on wheat seed germination and growth. Taken together, the binary complex of RPMG3 demonstrates potential as an environmentally friendly green washing agent capable of in reducing heavy metals from farmland soil with great efficiency, even at low liquid-solid ratios
Enhanced Selectivity in Microdroplet-Mediated Enzyme Catalysis
No full textNatural enzymes with enhanced catalytic activity and selectivity have long been studied by tuning the microenvironment around the active site, but how to modulate the active-site electric field in a simple fashion remains challenging. Here, we demonstrate that microdroplets as a simple yet versatile reactor can enhance the electric field at the active site of an enzyme. By using horseradish peroxidase as a model, improved selectivity in microdroplet-mediated enzyme catalysis can be obtained. Quantum mechanical/molecular dynamics calculations and vibrational Stark spectroscopy reveal that the electric field at the microdroplet interface can influence the electrostatic preorganization and orientation of the enzyme to enhance its internal electric field. As a result, the free energies of the substrate and heme can be tuned by the internal electric field, thereby changing its catalytic reaction pathway for a classical substrate, 3,3 ',5,5 '-tetramethylbenzidine, and enabling selective C-N additions for specific substrates. This finding provides a green, simple, and effective way to modulate enzyme-catalyzed reactions and holds promise for a broad spectrum of biosensing and biosynthesis applications
Complex Network Model of Global Financial Time Series Based on Different Distance Functions
No full textBy constructing a complex network model grounded in time series analysis, this study delves into the intricate relationships between the stock markets of 18 countries worldwide. Utilizing 31 distinct time series distance functions to formulate the network, we employ Hamming distance to quantify the resemblance between networks derived from different distance functions. By modulating the network density through distance percentiles (p=0.1, 0.3, 0.5), we demonstrate the similarity of various distance functions across multiple density levels. Our findings reveal that certain distance functions exhibit high degrees of similarity across varying network densities, suggesting their potential for mutual substitution in network construction. Furthermore, the centroid network identified via hierarchical cluster analysis highlights the similarities between the stock markets of different nations, mirroring the intricate interconnections within the global financial landscape. The insights gained from this study offer crucial perspectives for comprehending the intricate network structure of global financial time series data, paving the way for further analysis and prediction of global financial market dynamics
Soil spatial heterogeneity created by river-sea interaction influences <i>Tamarix chinensis</i> root features in the Yellow River Delta
No full textSalt-tolerant Tamarix chinensis roots are crucial in preserving wetland soil and carbon sequestration, which is essential for wetland ecology. Soil-water-salt conditions influence the growth of these roots in coastal saline areas, but the specific factors and their effects remain unclear. Using principal component and partial least square-structural equation modelling (SEM) methods, we studied T. chinensis root features in six Yellow River delta communities. Results showed varied root features across locations, with larger roots further inland. Root growth negatively correlated with soil texture and salinity and positively with groundwater levels. Soil texture and salinity decreased with distance from the coast, while groundwater increased with distance from the Yellow River. This suggests that geographical location influences soil-water-salt conditions, impacting root characteristics. The principal component analysis-derived root feature index captured 56.7% of root feature variation. SEM revealed geographical locations indirectly influence root features, with the Yellow River's proximity primarily affecting them through groundwater and coastal distance influencing via soil sand content and salinity. The study underscores the importance of these findings for wetland conservation and ecology
W/O/W Pickering emulsions stabilized by complex modified phycocyanin
No full textBACKGROUND: A water-in-oil-in-water (W/O/W) double emulsion can simultaneously load hydrophilic and hydrophobic sub-stances due to its unique two-membrane, three-phase structure. However, thermodynamic instability greatly limits the appli-cation of double emulsions in food processing. Further development of Pickering emulsions based on proteins, etc., canimprove the stability and loading capacity. It is of great significance to promote their practical application. RESULTS: Herein, we prepared ultrasound pretreatment complex glycation-modified phycocyanin (UMPC) to stabilize a W/O/WPickering emulsion for the codelivery of vitamin B12 (VB12) and vitamin E (VE). First, an inner water phase and oil phase con-taining polyglycerin polyricinoleate were homogenized to prepare a W/O emulsion. Subsequently, the W/O emulsion washomogenized with an outer water phase containing UMPC to obtain a W/O/W Pickering emulsion. A gel-like inner phase emul-sion with excellent storage and thermal stabilities was obtained under the condition that the W/O emulsion volume ratio was80% and the UMPC was stabilized by 10 g kg-1. The double emulsion after loading VB12 and VE showed good encapsulationeffect during the storage period, the encapsulation rate could reach more than 90%, it also showed excellent protection effectunder long-time storage and UV irradiation and the retention rate increased by more than 65%. In addition, the bioavailabilityof VB12 and VE significantly increased during simulated gastrointestinal digestion and reached 46.02% and 52.43%,respectively. CONCLUSION: These results indicate that the UMPC-stabilized W/O/W Pickering emulsion is an effective carrier for the codeliv-ery of hydrophilic and hydrophobic bioactive molecules and also provides a means for useful exploration of an efficient andstable emulsion system stabilized by biological macromolecules
Artificial wetlands providing space gain for the suitable habitat of coastal Pied Avocet
No full textA large number of artificial wetlands have replaced natural wetlands along waterbird migration routes to supply breeding, resting and feeding grounds for waterbirds. Effective identification of potential artificial wetlands that could serve as suitable habitats for waterbirds can provide important reference for field investigation and waterbird conservation. In this study, the habitat suitability of the Pied Avocet in the Yellow River Delta (YRD), China was simulated with the optimized MaxEnt model based on its occurrence records and environmental variables. The results showed that the MaxEnt model could well predict the habitat suitability of the Pied Avocet (Recurvirostra avosetta) in the YRD. The suitable habitats were distributed in the specific areas of the coastal zone, and artificial wetlands such as salt pans and mariculture ponds were the main components in the high-suitability area. The top three environmental factors affecting habitat selection were the land use and land cover (LULC), distance to the coastline and normalized difference vegetation index (NDVI). This paper emphasizes the role of artificial wetlands in providing suitable habitat for waterbirds. In order to better protect the habitat of waterbirds and alleviate human-bird conflict in the YRD, some targeted suggestions were put forward for the management gap of artificial wetlands. This study has strong practical significance for the protection and habitat management of waterbirds in the YRD. The methodology we employed is transferable to other wetlands, where efficient management is inhibited due to a lack of comprehensive field investigations