Dual nitrate isotopes (δ15N/δ18O-NO3−) are an effective tool for tracing nitrate sources in freshwater systems worldwide. However, the initial δ15N/δ18O values of different nitrate sources might be ...altered by isotopic fractionation during nitrification, thereby limiting the efficiency of source apportionment results. This study integrated hydrochemical parameters, site-specific isotopic compositions of potential nitrate sources, multiple stable isotopes (δD/δ18O-H2O, δ15N/δ18O-NO3− and Δ17O-NO3−), soil incubation experiments assessing the nitrification 15N-enrichment factor (εN), and a Bayesian mixing model (MixSIAR) to reduce/eliminate the influence of 15N/18O-fractionations on nitrate source apportionment. Surface water samples from a typical drinking water source region were collected quarterly (June 2021 to March 2022). Nitrate concentrations ranged from 0.35 to 3.06 mg/L (mean = 0.78 ± 0.46 mg/L), constituting ∼70 % of total nitrogen. A MixSIAR model was developed based on δ15N/δ18O-NO3− values of surface waters and the incorporation of a nitrification εN (−6.9 ± 1.8 ‰). Model source apportionment followed: manure/sewage (46.2 ± 10.7 %) > soil organic nitrogen (32.3 ± 18.5 %) > nitrogen fertilizer (19.7 ± 13.1 %) > atmospheric deposition (1.8 ± 1.6 %). An additional MixSIAR model coupling δ15N/δ18O-NO3− with Δ17O-NO3− and εN was constructed to estimate the potential nitrate source contributions for the June 2021 water samples. Results revealed similar nitrate source contributions (manure/sewage = 43.4 ± 14.1 %, soil organic nitrogen = 29.3 ± 19.4 %, nitrogen fertilizer = 19.8 ± 13.8 %, atmospheric deposition = 7.5 ± 1.6 %) to the original MixSIAR model based on εN and δ15N/δ18O-NO3−. Finally, an uncertainty analysis indicated the MixSIAR model coupling δ15N/δ18O-NO3− with Δ17O-NO3− and εN performed better as it generated lower uncertainties with uncertainty index (UI90) of 0.435 compared with the MixSIAR model based on δ15N/δ18O-NO3− (UI90 = 0.522) and the MixSIAR model based on δ15N/δ18O-NO3− and εN (UI90 = 0.442).
Display omitted
•Nitrification was identified as the major process controlling nitrogen dynamics.•15N-enrichment factor in nitrification was determined as −6.9 ± 1.8 ‰ by soil incubation experiment.•MixSIAR model identified MS as the dominant nitrate source.•Coupling δ15N/δ18O/Δ17O-NO3− and εN reduced the uncertainty of source apportionment.
Nitrate pollution is of considerable global concern as a threat to human health and aquatic ecosystems. Nowadays, δ15N/δ18O-NO3− combined with a Bayesian-based SIAR model are widely used to identify ...riverine nitrate sources. However, little is known regarding the effect of variations in pollution source isotopic composition on nitrate source contributions. Herein, we used δ15N/δ18O-NO3−, SIAR modeling, probability statistical analysis and a perturbing method to quantify the contributions and uncertainties of riverine nitrate sources in the Wen-Rui Tang River of China and to further investigate the model sensitivity of each nitrate source. The SIAR model confirmed municipal sewage (MS) as the major nitrate source (58.5–75.7%). Nitrogen fertilizer (NF, 8.6–20.9%) and soil nitrogen (SN, 7.8–20.1%) were also identified as secondary nitrate sources, while atmospheric deposition (AD, <0.1–7.9%) was a minor source. Uncertainties associated with NF (UI90 = 0.32) and SN (UI90 = 0.30) were high, whereas those associated with MS (UI90 = 0.14) were moderate and AD low (UI90 = 0.0087). A sensitivity analysis was performed for the SIAR modeling and indicated that the isotopic composition of the predominant source (i.e., MS in this study) had the strongest effect on the overall riverine nitrate source apportionment results.
Display omitted
•Sensitivity analysis was performed firstly for SIAR modeling.•δ15N/δ18O-NO3− and SIAR identified MS as the possible major nitrate source.•Uncertainties of source contributions decreased in the order: NF > SN > MS > > AD.•Model results are most sensitive to isotopic composition of major nitrate source.
Display omitted
•Use of NIR spectroscopy to predict the protein, fat and ash in S. fusiforme.•The seedling and early growth stages of S. fusiforme presented high protein levels.•CARS-PLS model ...exhibited superior prediction performance.•A customer-oriented quality control strategy was proposed.
Seaweed is a sustainable source of nutrients for human consumption, and a rapid and accurate quality control approach is essential for ensuring the nutritional value and health benefits of seaweed. The nutritional constituents and quality of seaweed vary significantly along with their growth stages. The present study developed a quality control approach for seaweed Sargassum fusiforme, rapid and convenient, using near-infrared spectroscopy (NIRS) and chemometrics to predict protein, fat, and ash in S. fusiforme at different growth stages. Partial least squares (PLS) regression was utilized to construct the quantitative relationship between NIR spectral data and nutritional components. Moreover, three wavelength selection algorithms, namely, competitive adaptive reweighted sampling (CARS), genetic algorithm, backward interval (BI) and synergy interval, were implemented to optimize the PLS models and improve prediction accuracy. Results demonstrated that the CARS-PLS model exhibited superior performance with a root mean square error of prediction and a coefficient of determination of prediction of 0.1075 % and 0.9936 for protein, 0.1807 % and 0.7706 for fat, and 0.3315 % and 0.9937 for ash, respectively. The effects of different developmental stages on the nutritional quality of S. fusiforme were also investigated. The seedling and early growth stages were the preferable harvest times for preparing high-protein foods and health supplements. The overall results confirmed the strong applicability of NIRS as a rapid and accurate method for measuring the protein, fat, and ash contents of S. fusiforme. This work also recommended that S. fusiforme quality can be controlled in a more precise and refined manner on the basis of a customer-oriented strategy.
Currently, the industrial application of bioelectrochemical systems (BESs) that are incubated with natural electrochemically active microbes (EABs) is limited due to inefficient extracellular ...electron transfer (EET) by natural EABs. Notably, recent studies have identified several novel living biomaterials comprising highly efficient electron transfer systems allowing unparalleled proficiency of energy conversion. Introduction of these biomaterials into BESs could fundamentally increase their utilization for a wide range of applications. This review provides a comprehensive assessment of recent advancements in the design of living biomaterials that can be exploited to enhance bioelectrocatalytic performance. Further, modular configurations of abiotic and biotic components promise a powerful enhancement through integration of nano-based artificial mediators and synthetic biology. Herein, recent advancements in BESs are synthesized and assessed, including heterojunctions between conductive nanomaterials and EABs, in-situ hybrid self-assembly of EABs and nano-sized semiconductors, cytoprotection in biohybrids, synthetic biological modifications of EABs and electroactive biofilms. Since living biomaterials comprise a broad range of disciplines, such as molecular biology, electrochemistry and material sciences, full integration of technological advances applied in an interdisciplinary framework will greatly enhance/advance the utility and novelty of BESs. Overall, emerging fundamental knowledge concerning living biomaterials provides a powerful opportunity to markedly boost EET efficiency and facilitate the industrial application of BESs to meet global sustainability challenges/goals.
Display omitted
•Biomaterials incorporating nano-based mediators and synthetic biology are used to improve bioelectrocatalytic performance.•Interfacial conductivity is improved through heterojunctions between conductive nanomaterials and EABs.•Additional electron flux in biohybrids is supplied from illuminated nano-sized semiconductors-derived photoelectrons.•LBL coating technologies to form core/shell structures are utilized for protecting living biohybrids using.•Intracellular electron flux of EAB is augmented by synthetic biological modifications of EABs and electroactive biofilms.
Herein, we have developed a robust Pd-catalyzed haloalkynylation of haloalkynes for the synthesis of dihaloalkenyne derivatives. This cross-haloalkynylation reaction proceeds in a highly chemo- and ...regioselective manner under mild conditions in the presence of two slightly structurally different haloalkynes and shows strong functional group tolerance under ligand- and base-free conditions.
Edible marine algae, often referred to as seaweeds, have health benefits and nutritional value. Origin discrimination of seaweeds is essential for quality assurance and traceability. As a rapid, ...easy, and economical method, near-infrared spectroscopy (NIR) was used in this study to investigate its ability to identify Sargassum fusiforme according to geographical origin, cultivar, and production method. A potential particle swarm optimization-support vector machine (PSO-SVM) identification model was constructed and exhibited its superiority in the origin determination of S. fusiforme. Results showed that the correct recognition rates were 90.00% for geographical origin, 100.00% for cultivar, and 100.00% for production method, when the PSO-SVM models were validated using the test sets. Overall, the results proved the potential of NIR spectroscopy combined with PSO-SVM models as a fast analytical method to trace the origin of S. fusiforme in terms of geographical origin, cultivar, and production method.
Display omitted
•This work presents a novel approach for the discrimination of Sargassum fusiforme.•NIR spectroscopy was used to identify Sargassum fusiforme from different origins.•PSO-SVM model provided satisfactory discrimination performance.
Tin (Sn), as the matrix of most lead-free solders, plays a primary role in stress absorption during the service of small-scale solder joints under cryogenic environment. The Sn grain orientation ...would produce a strong effect on the cryogenic mechanical stability of solder joints due to the anisotropy of Sn with a body-centered tetragonal structure. Here, a clear dependence of grain orientation on the strain-hardening behaviors of Sn at the liquid nitrogen temperature (~ 77 K) was revealed through a convenient and off-line Vickers micro-indentation test within various individual Sn grains. As a comparison, the same micro-indentation tests were also performed at room temperature (~ 293 K). By analyzing the hardness and impression morphology of different indented grains, it is found that Sn grain exhibits a hardening effect with a higher hardness value and a sink-in indentation morphology when the indented crystallographic direction deviates from
c
axis at 77 and 293 K. The tendency to become harder is attributed to reduction in the resolved shear stress on {100}001 slip system with the deviation, which renders dislocation slip more difficult to be activated. This orientation-dependent hardening effect becomes more pronounced at 77 K because of the occurrence of {301} deformation twinning and the same decrease of resolved shear stress on {301} deformation twinning with the deviation.
Abstract
A protocol was described to access diverse isothiazoles with functionalization potential
via
transition metal‐free three‐component annulation of alkynones, potassium ethylxanthate (EtOCS
2
...K) and ammonium iodide (NH
4
I). A sequential regioselective hydroamination/thiocarbonylation/intramolecular cyclization cascade achieved the efficient formation of consecutive C−N, C−S and N−S bonds in a one‐pot process.
magnified image
Spalling of intermetallic compounds is a common and detrimental phenomenon in the wetting reaction between Sn-based solders and under-bump metallizations; however, it is still not clear whether ...spalling will appear in solid-state aging. Here, the solid-state spalling of Ag-Sn intermetallic compounds at the interface between an eutectic Sn-Pb solder and an Ag/Ge substrate are examined during aging. Scanning electron microscopy (SEM) observations showed that Ag-Sn intermetallic compounds departed from the Ge substrate after the silver thin film was completely depleted during solid-state aging. This solid-state detachment of Ag-Sn intermetallic compounds was substantiated using deep etching. Despite this significant change in interfacial architecture caused by spalling, there is no considerable decline in the shear strength, implying that the interfacial joining was still effective. Thermodynamic analysis suggests that the spalling may be attributed to the open rapid diffusion paths among scalloped Ag
3
Sn in solid-state aging, limited thickness of the Ag layer and poor adhesion between Ag
3
Sn and the Ge substrate.
Display omitted
•A comprehensive quality assessment strategy for Bupleuri Radix was developed.•NIR spectroscopy was used for origin identification and content determination.•SVM model provided ...satisfactory discrimination performance.•CARS-SVM model provided acceptable accuracy in the prediction of quality indicators.
The quality of popular Chinese herbal medicine Bupleuri Radix (BR) is essential to its curative effect and economic value and has become an issue for customers and dealers. Traditional analytical techniques for evaluating BR quality are generally time-consuming, laborious, and costly. In this regard, a rapid and efficient method is warranted to supplement existing approaches. This study developed a comprehensive strategy based on near-infrared (NIR) spectroscopy and chemometrics for quality assessment of BR. From qualitative perspective, BR was identified according to geographical origin by using principal component analysis (PCA), partial least square-discriminant analysis (PLS-DA), and support vector machine (SVM). Saikosaponin A, saikosaponin D, polysaccharides, and total flavonoids, which are vital quality indicators of BR, were quantified through NIR spectroscopy and calibration models. Herein, a CARS-SVM model was constructed based on competitive adaptive reweighted sampling and SVM algorithm, and its prediction performance was compared with other calibration models (Full-PLS, CARS-PLS, and Full-SVM). Results indicated that the SVM model performed better than PCA and PLS-DA and had correct recognition rates of 97.37% and 94.44% in the calibration and prediction sets, respectively. The contents of saikosaponin A, saikosaponin D, polysaccharides, and total flavonoids were satisfactorily predicted through the CARS-SVM model. The coefficient of determination (Rp2) and root mean square error in the independent test sets (RMSEP) were 0.9135 and 0.0837%, 0.8132 and 0.1695%, 0.8810 and 0.7165%, and 0.7471 and 0.1766% for saikosaponin A, saikosaponin D, polysaccharides, and total flavonoids, respectively. The superiority of CARS-SVM compared with the other quantitative models demonstrated that CARS wavelength selection method and nonlinear SVM regression tool significantly improved the model performance. Overall the results demonstrated the potential of NIR spectroscopy and appropriate chemometrics for rapid quality evaluation of BR. The developed comprehensive quality assessment strategy could supplement existing methods for analysis of BR and is expected to provide reference for quality evaluation and control of other Chinese herbal medicines.
