Electrolyte Design with Dual -C≡N Groups Containing Additives to Enable High-Voltage Na3V2(PO4)2F3-Based Sodium-Ion Batteries.

Na3V2(PO4)2F3 is recognized as a promising cathode for high energy density sodium-ion batteries due to its high average potential of ∼3.95 V (vs Na/Na+). A high-voltage-resistant electrolyte is of high importance due to the long duration of 4.2 V (vs Na/Na+) when improving cyclability. Herein, a targeted electrolyte containing additives with two -C≡N groups like succinonitrile has been designed. In this design, one -C≡N group is accessible to the solvation sheath and enables the other -C≡N in dinitrile being exposed and subsequently squeezed into the electric double layer. Then, the squeezed -C≡N group is prone to a preferential adsorption on the electrode surface prior to the exposed -CH2/-CH3 in Na+-solvent and oxidized to construct a stable and electrically insulating interface enriched CN-/NCO-/Na3N. The Na3V2(PO4)2F3-based sodium-ion batteries within a high-voltage of 2-4.3 V (vs Na/Na+) can accordingly achieve an excellent cycling stability (e.g., 95.07% reversible capacity at 1 C for 1,5-dicyanopentane and 98.4% at 2 C and 93.0% reversible capacity at 5 C for succinonitrile after 1000 cycles). This work proposes a new way to design high-voltage electrolytes for high energy density sodium-ion batteries.

DNAzyme-Derived Aptamer Reversely Regulates the Two Types of Enzymatic Activities of Covalent-Organic Frameworks for the Colorimetric Analysis of Uranium.

Nanozymes are nanomaterials with enzyme-mimetic activity. It is known that DNA can interact with various nanozymes in different ways, enhancing or inhibiting the activity of nanozymes, which can be used to develop various biosensors. In this work, we synthesized a photosensitive covalent-organic framework (Tph-BT) as a nanozyme, and its oxidase and peroxidase activities could be reversely regulated by surface modification of single-stranded DNA (ssDNA) for the colorimetric detection of UO22+. Tph-BT exhibits excellent oxidase activity and weak peroxidase activity, and it is surprising to find that the UO22+-specific DNA aptamer can significantly inhibit the oxidase activity while greatly enhancing the peroxidase activity. The present UO22+ interacts with the DNA aptamer to form secondary structures and detaches from the surface of Tph-BT, thereby restoring the enzymatic activity of Tph-BT. Based on the reversed regulation effects of the DNA aptamer on the two types of enzymatic activities of Tph-BT, a novel "off-on" and "on-off" sensing platform can be constructed for the colorimetric analysis of UO22+. This research demonstrates that ssDNA can effectively regulate the different types of enzymatic activities of single COFs and achieve the sensitive and selective colorimetric analysis of radionuclides by the naked eye.

Reversed Regulation Effects of ssDNA on the Mimetic Oxidase and Peroxidase Activities of Covalent Organic Frameworks.

Nanomaterials with enzyme mimetic activity have attracted extensive attention, especially in the regulation of their catalytic activities by biomolecules or other polymers. Here, a covalent organic framework (Tph-BT COF) with excellent photocatalytic activity is constructed by Schiff base reaction, and its mimetic oxidase activity and peroxidase activity is inversely regulated via single-stranded DNA (ssDNA). Under light-emitting diode (LED) light irradiation, Tph-BT exhibited outstanding oxidase activity, which efficiently catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to produce blue oxTMB, and ssDNA, especially those with poly-thymidine (T) sequences, can significantly inhibit its oxidase activity. On the contrary, Tph-BT showed weak peroxidase activity, and the presence of ssDNA, particularly poly-cytosine (C) sequences, can remarkably enhance the peroxidase activity. The influence of base type, base length, and other factors on the activities of two enzymes is also studied, and the results reveal that the adsorption of ssDNA on the surface of Tph-BT prevented intersystem crossing (ISC) and energy transfer processes to reduce 1 O2 generation, while the electrostatic interaction between ssDNA and TMB enhanced Tph-BT's affinity for TMB to facilitate the electron transfer from TMB to • OH. This study investigates multitype mimetic enzyme activities of nonmetallic D-A conjugated COFs and demonstrates their feasibility of regulation by ssDNA.

The integrated common-sense model of illness self-regulation: predicting healthy eating, exercise behaviors, and health among individuals at risk of metabolic syndrome.

BACKGROUND: Little is known about the potential mechanisms of healthy eating and exercise change, and design interventions which aim to promote healthy eating and exercise change among individuals at risk of metabolic syndrome. This study aimed to identify key determinants of healthy eating, exercise behaviors, and health among individuals at risk of metabolic syndrome using the integrated common-sense model of illness self-regulation. METHOD: A cross-sectional study with a multi-wave data collection strategy. A total of 275 participants at risk of metabolic syndrome based on the clinical prediction model were included in the final analysis. Path analysis was employed to explore the pattern of relationships between key variables using AMOS. RESULTS: The mediation analysis suggested that personal and treatment control, and coherence can positively affect self-reported health via intentions and health behaviors (exercise and healthy eating). Additionally, relationships between self-efficacy (exercise and healthy eating) and health outcomes can be mediated by health behaviors, and both intentions and health behaviors. CONCLUSIONS: This current research used the integrated common-sense model of illness self-regulation to predict healthy eating, exercise behaviors, and self-reported health among individuals at risk of metabolic syndrome. The results suggested that self-efficacy, intention, consequences, personal control, treatment control, and coherence were the key determinants of behavior and health, which can help design interventions to encourage healthy eating and exercise changes among individuals with a high risk of MetS.

Web-Based Interventions for Pregnant Women With Gestational Diabetes Mellitus: Systematic Review and Meta-analysis.

BACKGROUND: Effective management of gestational diabetes mellitus (GDM) is essential because it is one of the most prevalent diseases during pregnancy, and the consequent condition maternal hyperglycemia is closely related to considerable short- and long-term maternal and neonatal complications. Web-based interventions (WBIs), defined as therapeutic interventions offered via the web, have been implemented to assist in managing GDM owing to their advantages of high accessibility and efficiency, but findings across relevant studies are inconsistent. OBJECTIVE: This systematic review and meta-analysis aimed to evaluate the effectiveness of WBIs on glycemic control among pregnant women with GDM; examine whether specific types of intervention interactivity, format, and technology have beneficial effects on maternal glycemic control; and comprehensively assess the efficacy of WBIs in maternal behavioral outcomes, cognitive and attitudinal outcomes, mental health, maternal and neonatal clinical outcomes, and medical service use and costs among pregnant women with GDM. METHODS: PubMed, Embase, Cochrane Library, Web of Science, CINAHL, and PsycINFO were searched from their respective inception to November 19, 2022, to identify relevant randomized controlled trials and controlled clinical trials. The methodological quality of the included studies was assessed using the Effective Public Health Practice Project tool. Where possible, the data for all outcomes were meta-analyzed using the Stata software (version 12.0; StataCorp). Overall, 3 subgroup analyses and post hoc sensitivity analyses of maternal glycemic control parameters were performed. RESULTS: Overall, 25 publications arising from 21 randomized controlled trials and controlled clinical trials were included. The overall meta-analyses on glycemic control parameters demonstrated that WBIs could significantly improve fasting blood glucose (standardized mean difference=-1.764, 95% CI -2.972 to -0.557; P=.004) and 2-hour postprandial blood glucose (standardized mean difference=-1.433, 95% CI -2.561 to -0.304; P=.01) compared with the control group, whereas no significant effect was found on glycated hemoglobin and 1-hour postprandial blood glucose. The results of the subgroup analyses indicated that mobile app-delivered interventions with a personalized format and interactive function showed more beneficial effects on maternal glycemic control. Moreover, WBIs could significantly enhance compliance with the self-monitoring of blood glucose; increase the rate of normal vaginal delivery; and decrease the chance of emergency cesarean, admission to the neonatal intensive care unit, and composite neonatal complications. GDM knowledge, risk perception of the disease, self-efficacy, satisfaction with care, and medical service use of the participants in the WBI group were also improved compared with the control group. However, the effectiveness of WBIs on other secondary outcomes was either nonsignificant or uncertain. CONCLUSIONS: WBIs are a promising approach to GDM management. Personalized, interactive, and mobile app-delivered interventions seem more worthy of being recommended for future clinical practice. Further high-quality studies are required to verify these findings before making broad recommendations. TRIAL REGISTRATION: PROSPERO CRD42022296625; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=296625.

Impact of contact with the baby following stillbirth on parental mental health and well-being: A systematic review and meta-analysis.

AIM: This study aims to identify and synthesize available research reporting parental mental health outcomes related to contact with a stillborn baby. BACKGROUND: Stillbirth is devastating events for parents. The effects of contact with the stillborn baby on parental mental health are uncertain. METHODS: This was a systematic review and meta-analysis carried out by searching six international electronic databases including PubMed, EMBASE, Cochrane, Web of Science, PsycINFO and CNKI databases from inception to 15 January 2023. Review Manager software was used for data analysis. RESULTS: Ten studies were included (n = 3974). Contact with a stillborn baby increased the risks of anxiety, depression and post-traumatic stress disorder in the short term and increased the risks of anxiety and post-traumatic stress disorder in the long term. Parents who had contact with a stillborn baby were more satisfied with their decision. Subgroup analysis showed that seeing a stillborn baby had no significant effect on anxiety or depression, but holding a stillborn baby increased the risks of anxiety. CONCLUSIONS: Caregivers should respect the parents' decision on whether to have contact with the stillborn baby and provide parents with continuous information, emotional and behavioural support after they have contact with stillborn babies.

Fluoro-Functionalized Spherical Covalent Organic Frameworks as a Liquid Chromatographic Stationary Phase for the High-Resolution Separation of Organic Halides.

The development of novel stationary phases with specific functionality is of great importance in chromatographic separation. Herein, we fabricated fluoro-functionalized spherical covalent organic frameworks (SF-COFs) via a bottom-up strategy as stationary phases for high-performance liquid chromatography (HPLC). Benefiting from the significant monodispersity, narrow size distribution, and high fluorine content, the SF-COFs packed column showed high column efficiency and excellent resolution for the separation of the organic fluorides involving polyfluorobenzenes, polychlorobenzenes, polybromobenzenes, perfluoroalkyl methacrylates, and halogenated trifluorotoluenes, which cannot be separated on the fluorine-free spherical covalent organic frameworks packed column. Especially, the column efficiency of 20 100-38 500 plates/m was obtained for polyfluorobenzenes, and the relative standard deviations of the retention time for continuous 10 separations of polychlorobenzenes and polybromobenzenes were less than 0.98%. Furthermore, the prepared SF-COFs packed column showed overwhelming superiority in the separation of organic halides compared with commercial C18 and pentafluorophenyl (PFP) packed columns. In addition, the compounds with different hydrophobicity or aromatic ring structure were also successfully separated on the SF-COFs packed column. This work extended the application of spherical COFs and provided a new way to introduce specific functional groups into the COF-based stationary phase for HPLC.

Construction of Two-Dimensional Fluorescent Covalent Organic Framework Nanosheets for the Detection and Removal of Nitrophenols.

In this work, we synthesized a two-dimensional fluorescent covalent-organic framework (TFPB-TTA COF) nanosheet by selecting and designing reactive monomers to realize the dual-functional processing of nitrophenols. The staggered benzene ring, triazine structure, and imine bond (C═N) of the TFPB-TTA COF can capture free nitrophenols through hydrogen bonding and conjugation interaction, and then, the photoinduced electron transfer and fluorescence resonance energy transfer (FRET) between the TFPB-TTA COF and nitrophenols affects the fluorescence emission of the TFPB-TTA COF, realizing the fluorescence sensing of nitrophenols. The large Ksv values and the low detection limit suggest that the TFPB-TTA COF can serve as sensitive and selective fluorescence sensors for nitrophenol detection in an aqueous system. At the same time, the strong interaction combined with the porous network structure of the TFPB-TTA COF facilitates the efficient adsorption and removal of nitrophenols. Especially for 2,4,6-trinitrophenol, the maximum adsorption capacity can reach 1045.53 mg/g with good recyclability and high structural stability of the TFPB-TTA COF. This work proposed a simple synthetic method for the construction of a fluorescent COF platform for the sensitive determination and efficient adsorption of nitrophenols.

New Jatrophane-Type Diterpenoids from Euphorbia kansui as Potential MDR Reversal Agents.

A serial jatrophane-type diterpenoids, comprised with three undescribed compounds kanesulones C-E (1-3) and four known ones (4-7), were obtained from the roots of Euphorbia kansui. The structures of compounds 1-3 were elucidated by detailed interpretation of their spectroscopic data, especially 2D-NMR and HR-ESI-MS, the absolute configuration of 1 was revealed by single crystal X-ray diffraction. These isolates were assayed for their multidrug resistance reversing activities on human breast adenocarcinoma cell line MCF-7/ADR. Compound 1 possessed potential as low toxic MDR modulator that could promote the efficacy of anticancer drug adriamycin ca. 85-fold at 5 µM, as 12 times stronger than the positive drug verapamil.

Covalent Organic Framework Nanofilm-Based Laser Desorption/Ionization Mass Spectrometry for 5-Fluorouracil Analysis and Tissue Imaging.

Although matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has become a ubiquitous and effective tool for macromolecules, direct analysis of small molecules by MALDI-MS using conventional organic matrices poses a challenge. Herein, a large-area, uniform, and stable covalent organic framework (COF) nanofilm prepared directly on indium-tin oxide (ITO) glass was first introduced as a substrate for LDI-MS, which showed enhanced sensitivity, no background interference, and high reproducibility in the analysis of diverse small molecules. Taking into account all these merits, an attractive approach of COF nanofilm-based LDI-MS was developed to quantitatively evaluate the pharmacokinetics of 5-fluorouracil (5-FU) in mouse plasma. A good linear relationship (10-20,000 ng/mL) and a low limit of detection (LOD) for 5-FU (∼100 pg/mL) were achieved. In view of the fact that the COF nanofilm was uniform and without the requirement of additional matrix spraying, it was further extended for LDI-MS imaging (LDI-MSI) to visualize the spatial distribution of 5-FU in mouse liver at different interval times after intravenous and intragastric administrations. The results indicated that the decay of 5-FU in mouse liver obtained with the COF nanofilm-based LDI-MSI was consistent with the tendency of 5-FU pharmacokinetics. This work not only offers an alternative solution for LDI-MS/MSI analysis of small molecules but also extends the application fields of COF nanofilm in MS research.

Facile Construction of Covalent Organic Framework Nanozyme for Colorimetric Detection of Uranium.

2D covalent organic frameworks (2D COFs) have been recognized as a novel class of photoactive materials owing to their extended π-electron conjugation and high chemical stabilities. Herein, a new covalent organic framework (Tph-BDP) is facilely synthesized by using a porphyrin derivative and an organic dye BODIPY derivative (5,5-difluoro-2,8-diformyl-1,3,7,9-tetramethyl-10-phenyl-5H-dipyrrolo[1,2-c:2',1'-f][1,3,2]diazabori-nin-4-ium-5-uide) as monomers for the first time, and their unique photosensitive properties endow them excellent simulated oxidase activity under 635 nm laser irradiation that can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). Further findings demonstrate that the presence of uranium (UO22+ ) can coordinate with imines of the oxidation products of TMB, thus modulating the charge transfer process of the colored products accompanied with intensive aggregation and remarkable color fading. This research provides a preparation strategy for COFs with excellent photocatalytic properties and nanozyme activity, and broadens the applications of the simple colorimetric methods for sensitive and selective radionuclide detection.

The experiences of nurses and midwives who provide surgical abortion care: A qualitative systematic review.

AIM: To synthesize qualitative evidence on nurses' and midwives' experiences in the provision of surgical abortion care. We address three specific questions: (a) what are the experiences of nurses and midwives in surgical abortion care? (b) what are their responses and coping strategies? (c) what are the deficiencies in surgical abortion care? DESIGN: Qualitative studies were synthesized using Thomas and Harden's qualitative thematic synthesis method. DATA SOURCES: Electronic databases, including PubMed, Embase, CINAHL, PsycINFO, Scopus and Web of Science were searched. Grey literature using ProQuest was searched. The databases were searched from inception to 5 August 2020. REVIEW METHODS: The SPIDER (Sample, Phenomenon of Interest, Design, Evaluation and Research type) search tool was used in the literature search. Data synthesis was conducted using the three-stage thematic synthesis method described by Thomas and Harden. RESULTS: 966 studies were identified in the initial search and 18 studies were included. Four analytical themes were generated: 'Providing abortion care requires high emotional labour'; 'Professionalism of abortion care providers'; 'Initiatives in professional development' and 'Improving directions for high-quality abortion care'. CONCLUSION: Nurses and midwives indicated that they require support to enhance psychological health and improve professional skills. Hospital managers should organize regular debriefing or structured group workshops for exchange of practical experiences and strengthening emotional support. More research is required to establish comprehensive training related to abortion care for nurses and midwives. The findings demonstrate that optimization of abortion services should start from hospital management models, pain management and bereavement care. IMPACT: Understanding the experiences of nurses and midwives in abortion provision will inform future clinical practice in surgical abortion care, which would be helpful in improving the professionalism and confidence of abortion providers. Our findings have implications for the training, development of policies and standards for surgical abortion care for nurses and midwives.

Ti4+-immobilized hierarchically porous zirconium-organic frameworks for highly efficient enrichment of phosphopeptides.

Ti4+-immobilized hierarchically porous zirconium-organic frameworks (denoted as THZr-MOFs) was prepared for phosphopeptide enrichment. The THZr-MOFs showed high specific surface area of 185.28 m2 g-1, wide pore-size distribution of 3 ~ 20 nm, good chemical stability and excellent hydrophilicity. Introduction of hierarchical pores in MOFs not only facilitated the accessibility of phosphopeptides to the internal metal affinity sites and reduce their mass transfer resistance, but also increased the exposure sites of metal affinity interaction and binding energies of Zr and Ti elements. Benefited from these advantages, the THZr-MOFs showed high adsorption capacity (79.8 µg mg-1) towards standard phosphopeptide. A low detection limit (0.05 fmol µL-1) and high enrichment selectivity (ß-casein/BSA with a molar ratio of 1:5000) were also obtained by MALDI-TOF MS. The THZr-MOFs were applied to analyze complex samples including nonfat milk, human serum, and HeLa cell lysate. In total, 1432 phosphopeptides derived from 762 phosphoproteins were identified from human HeLa cell lysate. Schematic representation of the application of Ti4+-immobilized hierarchically porous zirconium-organic frameworks (denoted as THZr-MOFs) in high-efficiency and selective enrichment of low-abundance phosphopeptides from the tryptic digest of human HeLa cell lysate.

A Coral-Like FeP@NC Anode with Increasing Cycle Capacity for Sodium-Ion and Lithium-Ion Batteries Induced by Particle Refinement.

We present a coral-like FeP composite with FeP nanoparticles anchored and dispersed on a nitrogen-doped 3D carbon framework (FeP@NC). Due to the highly continuous N-doped carbon framework and a spring-buffering graphitized carbon layer around the FeP nanoparticle, a sodium-ion battery with the FeP@NC composite exhibits an ultra-stable cycling performance at 10 A g-1 with a capacity retention of 82.0 % in 10 000 cycles. Also, particle refinement leads to a capacity increase during cycling. The FeP nanoparticles go through a refining-recombination process during the first cycle and present a global refining trend after dozens of cycles, which results in a gradually increase in graphitization degree and interface magnetization, and further provides more active sites for Na+ storage and contributes to a rising capacity with cycling. The capacity ascending phenomenon can also extend to lithium-ion batteries.

Top-Down Determination of Black Carbon Emissions from Oil Sand Facilities in Alberta, Canada Using Aircraft Measurements.

Black carbon (BC) emissions from the Canadian oil sand (OS) surface mining facilities in Alberta were investigated using aircraft measurements. BC emission rates were derived with a top-down mass balance approach and were found to be linearly related to the volume of oil sand ore mined at each facility. Two emission factors were determined from the measurements; production-based BC emission factors were in the range of 0.6-1.7 g/tonne mined OS ore, whereas fuel-based BC emission factors were between 95 and 190 mg/kg-fuel, depending upon the facility. The annual BC emission, at 707 ± 117 tonnes/year for the facilities, was determined using the production-based emission factors and annual production data. Although this annual emission is in reasonable agreement with the BC annual emissions reported in the latest version of the Canadian national BC inventory (within 16%), the relative split between off-road diesel and stack sources is significantly different between the measurements and the inventory. This measurement evidence highlights the fact that the stack sources of BC may be overestimated and the off-road diesel sources may be underestimated in the inventory and points to the need for improved BC emission data from diesel sources within facilities.

Using continous wavelet analysis for monitoring wheat yellow rust in different infestation stages based on unmanned aerial vehicle hyperspectral images.

Yellow rust is the most extensive disease in wheat cultivation, seriously affecting crop quality and yield. This study proposes sensitive wavelet features (WFs) for wheat yellow rust monitoring based on unmanned aerial vehicle hyperspectral imagery of different infestation stages [26 days after inoculation (26 DAI) and 42 DAI]. Furthermore, we evaluated the monitoring ability of WFs and vegetation indices on wheat yellow rust through linear discriminant analysis and support vector machine (SVM) classification frameworks in different infestation stages, respectively. The results show that WFs-SVM have promising potential for wheat yellow rust monitoring in both the 26 DAI and 42 DAI stages.

Size-Controllable Synthesis of Uniform Spherical Covalent Organic Frameworks at Room Temperature for Highly Efficient and Selective Enrichment of Hydrophobic Peptides.

Covalent organic frameworks (COFs) represent a new class of porous crystalline polymers with a diversity of applications. However, synthesis of uniform spherical COFs poses a great challenge. Here, we present size-controllable synthesis of uniform spherical COFs from nanometer to micrometer scale by a facile approach at room temperature. The as-prepared spherical COFs with different sizes exhibited ultrahigh surface area, good crystallinity, and chemical/thermal stability. Multifarious microscopic and spectroscopic techniques were performed to understand the formation mechanism and influencing factors of the spherical COFs. Moreover, the general applicability for room-temperature synthesis of the spherical COFs was demonstrated by varying different building blocks. Spherical COFs, because of the advantageous nature of their surface area, hydrophobicity, and mesoporous microenvironment, serve as an attractive restricted-access adsorption material for highly selective and efficient enrichment of hydrophobic peptides and size exclusion of macromolecular proteins simultaneously. On this basis, the spherical COFs were successfully applied to the specific capture of ultratrace C-peptide from human serum and urine samples. This research provides a new strategy for room-temperature controllable synthesis of uniform spherical COFs with different sizes and extends the application of COFs as an attractive sample-enrichment probe for clinical analysis.

Characteristics of women with mixed mass formation after evacuation following uterine artery chemoembolization for cesarean scar pregnancy.

PURPOSE: To explore the efficacy of treatment for early cesarean scar pregnancy (CSP) and to evaluate the characteristics of women with subsequent mixed mass formation. METHODS: Women with CSP, who received UACE followed by evacuation, were retrospectively analyzed. Clinical/sonographic characteristics in patients with or without mixed mass formation were compared. RESULTS: From a total of 395 cases, 105 cases had a pregnancy residual with mixed mass formation. Blood loss and subsequent salvage intervention were significantly lower in patients without mixed mass, although all women retained their uteri. It required 50 days for the mass to resolve, 40 days for ß-hCG concentrations to drop back to normal, and 61 days for menses to be restored; all of which were significantly longer than the same indices in women without a mixed mass. Clinical/sonographic characteristics predicting residual mass formation were maximal diameter of gestational sac (OR = 1.05, P = 0.001, with a sensitivity and specificity of 68.6 and 80.3%, respectively), presence of a fetal heart beat (OR = 2.63, P = 0.002, with a sensitivity and specificity of 62.9 and 67.2%, respectively), remnant myometrial thickness (OR = 108.91, P = 0.001 when thickness was less than 1 mm, with a sensitivity and specificity of 42.9% and 96.6%), location of gestational sac (OR = 59.20, P = 0.01 for complete type, with a sensitivity and specificity of 99.0 and 36.9%), and Doppler signal grading (OR = 8.08, P = 0.013 for Grade III, with a sensitivity and specificity of 83.8 and 51.0%). CONCLUSIONS: UACE followed by evacuation was effective for CSP and subsequent mixed mass formation could be predicted by some clinical/sonographic characteristics.

New Spectral Index for Detecting Wheat Yellow Rust Using Sentinel-2 Multispectral Imagery.

Yellow rust is one of the most destructive diseases for winter wheat and has led to a significant decrease in winter wheat quality and yield. Identifying and monitoring yellow rust is of great importance for guiding agricultural production over large areas. Compared with traditional crop disease discrimination methods, remote sensing technology has proven to be a useful tool for accomplishing such a task at large scale. This study explores the potential of the Sentinel-2 Multispectral Instrument (MSI), a newly launched satellite with refined spatial resolution and three red-edge bands, for discriminating between yellow rust infection severities (i.e., healthy, slight, and severe) in winter wheat. The corresponding simulative multispectral bands for the Sentinel-2 sensor were calculated by the sensor's relative spectral response (RSR) function based on the in situ hyperspectral data acquired at the canopy level. Three Sentinel-2 spectral bands, including B4 (Red), B5 (Re1), and B7 (Re3), were found to be sensitive bands using the random forest (RF) method. A new multispectral index, the Red Edge Disease Stress Index (REDSI), which consists of these sensitive bands, was proposed to detect yellow rust infection at different severity levels. The overall identification accuracy for REDSI was 84.1% and the kappa coefficient was 0.76. Moreover, REDSI performed better than other commonly used disease spectral indexes for yellow rust discrimination at the canopy scale. The optimal threshold method was adopted for mapping yellow rust infection at regional scales based on realistic Sentinel-2 multispectral image data to further assess REDSI's ability for yellow rust detection. The overall accuracy was 85.2% and kappa coefficient was 0.67, which was found through validation against a set of field survey data. This study suggests that the Sentinel-2 MSI has the potential for yellow rust discrimination, and the newly proposed REDSI has great robustness and generalized ability for yellow rust detection at canopy and regional scales. Furthermore, our results suggest that the above remote sensing technology can be used to provide scientific guidance for monitoring and precise management of crop diseases and pests.

Identification of Wheat Yellow Rust Using Optimal Three-Band Spectral Indices in Different Growth Stages.

Yellow rust, a widely known destructive wheat disease, affects wheat quality and causes large economic losses in wheat production. Hyperspectral remote sensing has shown potential for the detection of plant disease. This study aimed to analyze the spectral reflectance of the wheat canopy in the range of 350⁻1000 nm and to develop optimal spectral indices to detect yellow rust disease in wheat at different growth stages. The sensitive wavebands of healthy and infected wheat were located in the range 460⁻720 nm in the early-mid growth stage (from booting to anthesis), and in the ranges 568⁻709 nm and 725⁻1000 nm in the mid-late growth stage (from filling to milky ripeness), respectively. All possible three-band combinations over these sensitive wavebands were calculated as the forms of PRI (Photochemical Reflectance Index) and ARI (Anthocyanin Reflectance Index) at different growth stages and assessed to determine whether they could be used for estimating the severity of yellow rust disease. The optimal spectral index for estimating wheat infected by yellow rust disease was PRI (570, 525, 705) during the early-mid growth stage with R² of 0.669, and ARI (860, 790, 750) during the mid-late growth stage with R² of 0.888. Comparison of the proposed spectral indices with previously reported vegetation indices were able to satisfactorily discriminate wheat yellow rust. The classification accuracy for PRI (570, 525, 705) was 80.6% and the kappa coefficient was 0.61 in early-mid growth stage, and the classification accuracy for ARI (860, 790, 750) was 91.9% and the kappa coefficient was 0.75 in mid-late growth stage. The classification accuracy of the two indices reached 84.1% and 93.2% in the early-mid and mid-late growth stages in the validated dataset, respectively. We conclude that the three-band spectral indices PRI (570, 525, 705) and ARI (860, 790, 750) are optimal for monitoring yellow rust infection in these two growth stages, respectively. Our method is expected to provide a technical basis for wheat disease detection and prevention in the early-mid growth stage, and the estimation of yield losses in the mid-late growth stage.