Graph-Based Method for Calibration of High-Resolution Mass Spectra of Natural Organic Matter

Inaccuracies in ion detection and signal processing can undermine confidence in the molecular formula assignment of high-resolution mass spectrometry, which relies on precise matching of the mass-to-charge ratio (m/z). This study proposes a novel graph-based spectra calibration method, MSCMcalib, which implements coordinate transformation and pattern detection. MSCMcalib maps uncalibrated m/z data onto a modified 2D mass defect plot, facilitating the automatic calibration of detected lines, i.e., the calibration of uncalibrated peaks aligned with these lines. The “propagation” method is subsequently employed to accurately and automatically calibrate 605 m/z values across multiple lines, encompassing 98% of the m/z range. The calibrated m/z values divide the m/z range of the spectrum into multiple subintervals, with each subinterval undergoing a process of “scaling” calibration. The utilization of narrower partitions effectively mitigates divergence issues at both ends that arise from the polynomial fitting of errors against m/z. The effectiveness of MSCMcalib is validated through the calibration of SRFA data with m/z error ranges spanning from −10 to −6 ppm, resulting in an additional assignment of 11%–30% more molecular formulas compared to the quadratic fitting calibration

Graph-Based Method for Calibration of High-Resolution Mass Spectra of Natural Organic Matter

Inaccuracies in ion detection and signal processing can undermine confidence in the molecular formula assignment of high-resolution mass spectrometry, which relies on precise matching of the mass-to-charge ratio (m/z). This study proposes a novel graph-based spectra calibration method, MSCMcalib, which implements coordinate transformation and pattern detection. MSCMcalib maps uncalibrated m/z data onto a modified 2D mass defect plot, facilitating the automatic calibration of detected lines, i.e., the calibration of uncalibrated peaks aligned with these lines. The “propagation” method is subsequently employed to accurately and automatically calibrate 605 m/z values across multiple lines, encompassing 98% of the m/z range. The calibrated m/z values divide the m/z range of the spectrum into multiple subintervals, with each subinterval undergoing a process of “scaling” calibration. The utilization of narrower partitions effectively mitigates divergence issues at both ends that arise from the polynomial fitting of errors against m/z. The effectiveness of MSCMcalib is validated through the calibration of SRFA data with m/z error ranges spanning from −10 to −6 ppm, resulting in an additional assignment of 11%–30% more molecular formulas compared to the quadratic fitting calibration

Data_Sheet_1_Proton Magnetic Resonance Spectroscopy for the Early Diagnosis of Parkinson Disease in the Substantia Nigra and Globus Pallidus: A Meta-Analysis With Trial Sequential Analysis.docx

This study aimed to investigate the metabolic changes in globus pallidus (GP) and substantia nigra (SN) during the early stage of Parkinson disease (PD) using magnetic resonance spectroscopy (MRS). PubMed, Embase, Web of Science, and Chinese National Knowledge Infrastructure were searched till November 2018. Eligible trials comparing early metabolic changes in GP and SN in patients with PD vs. controls were included. The mean differences with 95% confidence intervals were estimated with either fixed- or random-effects models using Review Manager 5.3 software. Trial sequential analysis was performed using TSA 0.9.5.10 beta software. Finally, 16 studies were selected from the search. Overall, the N-acetyl aspartate-to-creatine ratio showed a significant difference between patients with early-stage PD and healthy controls. The overall heterogeneity was P 2 = 94% in GP and P = 0.0002, I2 = 74% in SN. The results revealed that MRS could be a more sensitive imaging biomarker in the diagnosis of early-stage PD.Systematic Review Registrationhttps://www.crd.york.ac.uk/prospero/display_record.php?RecordID=125731, registration number: CRD42019125731.</p

Control of the Redox Activity of Quantum Dots through Introduction of Fluoroalkanethiolates into Their Ligand Shells

Increasing the fraction of 1<i>H</i>,1<i>H</i>,2<i>H</i>,2<i>H</i>-perfluorodecanethiol (PFDT) in the mixed-PFDT/oleate ligand shell of a PbS quantum dot (QD) dramatically reduces the permeability of the ligand shell to alkyl-substituted benzoquinones (s-BQs), as measured by a decrease in the efficiency of collisional photoinduced electron transfer. Replacing only 21% of the oleates on the QD surface with PFDT reduces the yield of photo-oxidation by tetramethyl BQ by 68%. Experiments with s-BQ quenchers of two different sizes reveal that the degree of protection provided by the PFDT-doped monolayer, relative to a decanethiolate (DT)-doped monolayer at similar coverage, is due to both size exclusion (PFDT is larger and more rigid than DT), and the oleophobicity of PFDT. This work demonstrates the usefulness of fluorinated ligands in designing molecule-selective and potentially corrosion-inhibiting surface coatings for QDs for applications as robust emitters or high fidelity sensing platforms

Molecular Characteristics and Formation Mechanisms of Unknown Ozonation Byproducts during the Treatment of Flocculated Nanofiltration Leachate Concentrates Using O₃ and UV/O₃ Processes

Both ozone (O3) and UV/O3 treatment processes can effectively remove organic matter in the flocculated membrane filtration concentrate from landfill leachate, but the ozonation byproducts (OBPs) generated in the processes remain unknown. Using electrospray ionization-coupled Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS), this study investigated the molecular characteristics of unknown OBPs and their formation mechanisms during the treatment of flocculated nanofiltration concentrate (FNFC) using the O3 and UV/O3 processes. The results showed that after being treated by the O3 and UV/O3 processes, the average value of the oxygen-to-carbon ratio (O/Cavg) in the FNFC organic matter increased substantially from 0.49 to 0.61–0.64 and 0.63–0.71, respectively, with an O3 dosage of 13.4–54.4 mg/min. The main OBPs were CHO and CHON compounds, which were mainly produced through oxygenation (+O2/+O3 and −H2+O2), oxidative deamination (−NH3+O2), decyclopropyl (−C3H4), and deisopropyl (−C3H6) reactions. The hydroxyl radical (•OH) can intensify these reactions, resulting in an abundance of OBPs with a high oxidation degree and low molecular weight. OBPs at five m/z values were fragmented and analyzed with tandem mass spectrometry, and abundant hydroxyl groups, carboxyl groups, and carbonyl groups were tentatively identified, presenting a potential toxicity to aquatic organisms. Due to the high molecular diversity of the OBPs in FNFC, their lower ΔGCoxo compared to natural fulvic acid, and potential toxicity, their impact on the water environment should be given more attention

“Click” Long Seesaw-Type A∼∼B∼∼A Chains Together into Huge Defect-Free Hyperbranched Polymer Chains with Uniform Subchains

“Click” Long Seesaw-Type A∼∼B∼∼A Chains Together into Huge Defect-Free Hyperbranched Polymer Chains with Uniform Subchain

Selective Orbital Coupling: An Adsorption Mechanism in Single-Atom Catalysis

Quantitative understanding of the chemisorption on single-atom catalysts (SACs) by their electronic properties is crucial for the catalyst design. However, the physical mechanism is still under debate. Here, the CO catalytic oxidation on single transition metal (i.e., Sc, Ti, V, Cr, Mn, Fe, Co, Ni) dopants is used as a theoretical model to explore the correlations between the characteristics of electronic structures and the chemisorption on SACs. For these metal dopants, their atomic d orbitals form several nondegenerate and localized electronic states that are found to be selectively coupled with the π* orbital of the adsorbed O2, which we defined as selective orbital coupling. Based on the selective orbital coupling, we find that the alignment between the selected d state and the π* state determines the bond strength, regardless of the electron occupation number of the selected d states; the electron transfer to form M–O bonding can be provided by the support. Such electron transfer can be related with the electronic metal–support interaction. We attribute the origin of the chemisorption mechanism to the coexistence of the localized orbital of the single transition metal and the continuous energy band of the Au support. Finally, we illustrate how this mechanism dominates the variation trend of the reaction barriers. Our results unravel a fundamental adsorption mechanism in SAC systems

Additional file 1 of Association of serum 25-hydroxy-vitamin D concentration and risk of mortality in cancer survivors in the United States

Supplementary Material 1

Table_1_Susceptibility-Guided Therapy vs. Bismuth-Containing Quadruple Therapy as the First-Line Treatment for Helicobacter pylori Infection: A Systematic Review and Meta-Analysis.docx

BackgroundThe increased antibiotic resistance of Helicobacter pylori (H. pylori) has led to the decreased efficacy of H. pylori regimens.AimTo evaluate the efficacy, safety, and compliance of susceptibility-guided therapy (SGT) vs. bismuth-containing quadruple therapy (BQT) as the first-line treatment for H. pylori infection.Materials and MethodsThis meta-analysis was performed in accordance with the PRISMA 2009 guidelines. A systematic search in PubMed, Embase, and Cochrane databases was conducted using the combination of “H. pylori or H. pylori or Hp,” “bismuth quadruple,” and “tailored eradication OR tailored therapy OR susceptibility-guided therapy OR personalized therapy OR antibiotic susceptibility testing.”ResultsFive studies with 2,110 H. pylori-infected patients were enrolled. The pooled eradication rates of SGT and BQT were 86 vs. 78% (p 0.05) by intention-to-treat (ITT) and per-protocol (PP) analyses, respectively. SGT has a significantly superior efficacy than BQT [pooled risk ratio (RR) = 1.14, p 0.05). The compliances of SGT and BQT were 95 and 92%, respectively.ConclusionCompared with BQT, SGT showed a higher efficacy and similar safety as the first-line treatment of H. pylori infection in areas with high antibiotic resistance. The decision-making of first-line regimens for H. pylori infection should depend on the availability and cost-effectiveness of susceptibility tests and bismuth in local areas.</p

DataSheet1_Spatial dynamics of dissolved organic matter among different segments of a large-scale reservoir in the water-level declining period.docx

Large-scale reservoirs exhibit complex hydrological conditions and exert a significant alteration on river flowing. Although dissolved organic matter (DOM) is noted to involve in biogeochemical processes, the variation mechanism of DOM chemistry across a large-scale reservoir is not well assessed. Here, we investigated four tributaries across different segments (e.g., the front and non-front areas) of the world’s largest Three Gorges Reservoir (TGR). Optical techniques and ultrahigh-resolution mass spectrometry were used to comprehensively explore the variation of DOM chemistry across TGR in the water-level declining period, and biological incubation experiments were conducted to trace its biogeochemical influences. We found that the variation of DOM composition and property between tributary and river mouth sites show different patterns between front and non-front areas of TGR. In particular, there was more terrestrial derived and biologically recalcitrant DOM in the river mouth than tributaries in the front area, while the opposite variation was observed in the non-front area. Integrated with hydrological information, the results demonstrated that the density current exerts a significant influence on DOM dynamics. Furthermore, the biological incubation experiments suggested that this variation of DOM property among tributaries would involve in the spatial dynamics of carbon dioxide (CO2) was emitted in TGR that more CO2 was emitted in the tributary of the front area than of the non-front area during the water-level declining period.</p