H2O2 Solution Research Articles

Concave Gold Nanocubes Exhibit Growth-Etching Behavior: Unexpected Morphological Transformations.

Chemical equilibrium stands as a fundamental principle governing the dynamics of chemical systems. However, it may become intricate when it refers to nanomaterials because of their unique properties. Here, we invesitigated concave gold nanocubes (CGNs) subjected to an akaline Au3+/H2O2 solution, which exhibit both etching and growth in a monotonic solution. When CGNs were subjected to an increasingly alkaline Au3+/H2O2 solution, their dimensions increased from 107 to 199 nm and then decreased to 125 nm. Transmission electron microscopy (TEM) demonstrated that their morphology undergoes intricate alternations from concave to mutibranch and finally to concave again. Real-time ultraviolet-visible spectroscopy and time-dependent TEM also demonstrated reduction first and then oxidation in one solution. Among the nanomaterials, the obtained carpenterworm-like gold nanoparticles revealed the best catalytic performance in p-nitrophenol reduction by NaBH4, with a chemical rate that continues to increase until the reaction reaches completion. Growth leading to atomic dislocation, distortion, and exposure on nanoparticles and the redox of H2O2 plausibly account for the further etching due to the Ostwald ripening effect. Our study may spur more interest in the tuning of the properties, engineering, investigation, and design of new kinds of nanomaterials.

Antibiotics in honey: a comprehensive review on occurrence and analytical methodologies.

Honey is a food of great nutritional importance and has always been used for human consumption. The production of honey and other beekeeping products depends on the proper functioning of this extremely important sector, as it has a direct impact on other sectors such as agriculture. The decline in bee colony numbers has been linked, among other factors, to bacterial diseases affecting bees, including American and European foulbrood, and Nosema spp. disease. In this matter, prophylactic or therapeutic use of veterinary drugs in apiculture is common but can lead to their accumulation in bees and in honey. Consumption of contaminated honey can have adverse effects such as allergic or hypersensitivity reactions, carcinogenicity, reproductive effects, and teratogenicity. Commission Regulation (EU) N⍛ 37/2010 sets MRLs for antibiotics in various foods, but these limits are not set for api-products. The lack of harmonized rules has led some countries to set recommended concentrations and minimum performance limits. Nonetheless, to achieve this goal, development of accurate and precise analytical methodologies is crucial. In recent years, the analysis of antibiotics in honey has led to the development of methods in an extensive range of families, including aminoglycosides, amphenicols, lincosamides, macrolides, nitroimidazoles, quinolones, sulfonamides, tetracyclines and nitrofurans. This review work entails an in-depth exploration of occurrence studies, extraction methodologies, and analytical techniques for the determination of antibiotics in apiculture products. It was found that the most used extraction methods include solid-phase extraction, dispersed solid or liquid phase extraction and QuEChERS. Due to the complexity of the honey matrix, samples are often diluted or acidified using McIlvaine buffer, H2O, MeOH, acidified ACN and TCA solution. This is usually followed by a purification step using SPE cartridges or PSA. Golden analytical methodologies include high-performance liquid chromatography coupled to a triple quadrupole mass spectrometer (MS/MS) with Orbitrap or Q-ToF detectors.

Mesoporous carbon-doped boron nitrides for cathodic and anodic hydrogen peroxide electrosynthesis

Mesoporous carbon-doped hexagonal boron nitrides (C-doped BN) with high surface area were prepared by annealing organic resin polymer/silica in NaBH4 and NaNH2 inorganic salts, which were found to be efficient metal-free bifunctional electrocatalyst for both 2e− ORR and 2e− WOR. It could efficiently catalyze 2e− ORR to H2O2 in 2 M KHCO3 (1650 mmol g−1 h−1) with Faraday efficiency of 93–98 % in half reaction, while it was very active for 2e− WOR to generate H2O2 in 2 M KHCO3 with 551 mmol g−1 h−1 H2O2 production rate in half reaction. When pairing them in one H-type cell, H2O2 solution could be totally produced over C-doped BN in both anode and cathode cells. The better electron conductivity from sharper band gap caused by carbon doping and higher surface area of 304 m2 g−1 contributed to its efficient electrocatalytic activity. The C-doped BN served an effective bifunctional electrocatalyst for 2e− ORR and 2e− WOR.

Photodegradation of a Broad-Spectrum Antibiotic Azithromycin Using H2O2 under Ultraviolet Irradiation.

The photodegradation of azithromycin present was carried out in water using H2O2 under UV irradiation. The reaction variables considered in this study were the amount of H2O2 solution and the initial concentration of azithromycin to evaluate the performance of the photodegradation process. The azithromycin degradation was not observed in the dark during stirring for 20 min. The study showed an efficient photodegradation of azithromycin using H2O2 as an oxidant in the presence of UV irradiation. The azithromycin degradation was altered significantly by the pH of the irradiated solution. The degradation was low at an acidic pH and showed an increasing trend as the pH changed to basic. The azithromycin degradation increased with a higher amount (higher concentration) of H2O2. The degradation of azithromycin decreased with a higher concentration of azithromycin in the reacting solution. The highest degradation of AZT was achieved in 1 h using a 1.0 ppm AZT solution containing 3 mL of H2O2. The experimental data obtained were well-fitted to zero-order reaction kinetics. The results of this study were found quite excellent. They showed 100% degradation in 1 h when compared with those reported in the literature, both with photocatalysis using nanomaterials and photolysis using light irradiation and/or H2O2. The UV/H2O2 system was found to be quite efficient for the photodegradation of azithromycin, and this system can be applied to degrade other organic pollutants present in industrial wastewater.

Stable detection of diazinon residues in vegetables by an electrochemiluminescent aptasensor based on the in-situ production of H2O2 from dual-catalytic glucose

Stable detection of diazinon (DZN) residues in vegetables is important for food safety. In this work, an electrochemiluminescence (ECL) aptasensor with dual-catalytic glucose in-situ production of H2O2 was constructed for the stable detection of DZN in vegetables. Firstly, MWCNTs@MB was prepared using π-π stacking interactions between methylene blue (MB) and multi-walled carbon nanotubes (MWCNTs) to enhance the loading of MB on an electrode and thus catalyze the generation of H2O2 from glucose. Secondly, Cu2O@AuNPs was formed by loading AuNPs on the surface of Cu2O through spontaneous reduction reaction, which improved the interfacial charge transfer, Cu2O nano-enzyme had glucose oxidase mimicking activity and could further catalyze the production of more H2O2 from glucose. MWCNTs@MB and Cu2O@AuNPs played a key role in the in-situ generation of co-reacting reagent H2O2, which solved the problem of unstable detection caused by the easy decomposition of the H2O2 solution added to the luminescence system. In addition, the aptamer was immobilized on the electrode surface by forming Au–S bonds with Cu2O@AuNPs. As a result, the ECL aptasensor performed good linearity in 1.00 pg mL−1-1.00 μg mL−1 and a low limit of detection (LOD) to 0.39 pg mL−1 (S/N = 3). This work provided an effective method for the accurate and stable detection of DZN residues in vegetables, which was of great significance in ensuring food safety and assessing the environmental risk of DZN.

A Cages-on-Cluster Structure Constructed by Post-Clustering Covalent Modifications and Guest-Enabled Stimuli-Responsive Luminescence.

A gold(I)-cluster-based twin-cage has been constructed by post-clustering covalent modification of a hexa-aldehyde cluster precursor with triaminotriethylamines. The cages-on-cluster structure has double cavities and four binding sites, which show site-discriminative binding for silver(I) and copper(I) guests. The guests in the tripodal hats affect the luminescence of the cluster: the tetra-silver(I) host-guest complex is weakly red-emissive, while the bis-copper(I)-bis-silver(I) one is non-emissive but is a stimuli-responsive supramolecule. The copper(I) ion inside the tri-imine cavity is oxidation sensitive, which enables the release of the bright emissive precursor cluster triggered by H2O2 solution. The hybridization of a cluster with cavities to construct a cluster-based cage presents an innovative concept for functional cluster design, and the post-clustering covalent modification opens up new avenues for finely tuning the properties of clusters.

A Cages‐on‐Cluster Structure Constructed by Post‐Clustering Covalent Modifications and Guest‐Enabled Stimuli‐Responsive Luminescence

AbstractA gold(I)‐cluster‐based twin‐cage has been constructed by post‐clustering covalent modification of a hexa‐aldehyde cluster precursor with triaminotriethylamines. The cages‐on‐cluster structure has double cavities and four binding sites, which show site‐discriminative binding for silver(I) and copper(I) guests. The guests in the tripodal hats affect the luminescence of the cluster: the tetra‐silver(I) host–guest complex is weakly red‐emissive, while the bis‐copper(I)‐bis‐silver(I) one is non‐emissive but is a stimuli‐responsive supramolecule. The copper(I) ion inside the tri‐imine cavity is oxidation sensitive, which enables the release of the bright emissive precursor cluster triggered by H2O2 solution. The hybridization of a cluster with cavities to construct a cluster‐based cage presents an innovative concept for functional cluster design, and the post‐clustering covalent modification opens up new avenues for finely tuning the properties of clusters.

Improvement of the photo-Fenton performance at near neutral pH by the addition of tannic acid from tea leaves waste as a complexing agent in the Pb(II) photo-oxidation

<p>IIntroducing tannic acid from tea leaves waste as a complexing agent of Fe(III) into photo-Fenton process to prevent Fe(OH)3 precipitation at pH 7, and further to increase photo-Fenton activity in the near neutral pH for Pb(II) photo-oxidation is systematically addressed. The photo-Fenton process for Pb(II) photo-oxidation involving Fe2+ and H2O2 solutions as well as UV light was conducted by batch technique, both in the absence and present of tannic acid. Furthermore, the optimization of tannic acid concentration, solution pH, and reaction time were also conducted. The research results assign that the addition of tannic acid in the photo-Fenton process for photo-oxidation of Pb(II) is able to considerably enhance the effectiveness at pH 6-8 (near neutral pH). The activity of the tannic acid from tea leaves waste is comparable to the that of the commercial tannic acid. The best condition of Pb(II) photo-oxidation having 10 mg.L-1 in 50 mL of the solution can be reached by using Fe2+ as high 10 mmol.L-1, H2O2 100 mmol.L-1, with the addition of tannic acid as much as 30 mg.L-1 at pH 7 and 60 min of the time that gave about 85% of the photo-oxidation effectiveness. It is also indicated that the Pb(II) photo-oxidation has resulted in the harmless PbO2 solid . Hence, it is obviously assigned that the priceless tea waste could significantly contribute in the improvement of the photo-Fenton performance to prevent environmental pollution.</p>

Asymmetric Assembly in Microdroplets: Efficient Construction of MOF Micromotors for Anti-Gravity Diffusion.

Janus-micromotors, as efficient self-propelled materials, have garnered considerable attention for their potential applications in non-agitated liquids. However, the design of micromotors is still challenging and with limited approaches, especially concerning speed and mobility in complex environments. Herein, a two-step spray-drying approach encompassing symmetrical assembly and asymmetrical assembly is introduced to fabricate the metal-organic framework (MOF)Janus-micromotors with hierarchical pores. Using a spray-dryer, a symmetrical assembly is first employed to prepare macro-meso-microporous UiO-66 with intrinsic micropores (<0.5nm) alongside mesopores (≈24nm) and macropores (≈400nm). Subsequent asymmetrical assembly yielded the UiO-66-Janus loaded with the reducible nanoparticles, which underwent oxidation by KMnO4 to form MnO2 micromotors. The micromotors efficiently generated O2 for self-propulsion in H2O2, exhibiting ultrahigh speeds (1135µm s-1, in a 5% H2O2 solution) and unique anti-gravity diffusion effects. In a specially designed simulated sand-water system, the micromotors traversed from the lower water to the upper water through the sand layer. In particular, the as-prepared micromotors demonstrated optimal efficiency in pollutant removal, with an adsorption kinetic coefficient exceeding five times that of the micromotors only possessing micropores and mesopores. This novel strategy fabricating Janus-micromotors shows great potential for efficient treatment in complex environments.

Atomistic Removal Mechanisms of SiC in Hydrogen Peroxide Solution.

To elucidate the atomic mechanisms of the chemical mechanical polishing (CMP) of silicon carbide (SiC), molecular dynamics simulations based on a reactive force field were used to study the sliding process of silica (SiO2) abrasive particles on SiC substrates in an aqueous H2O2 solution. During the CMP process, the formation of Si-O-Si interfacial bridge bonds and the insertion of O atoms at the surface can lead to the breakage of Si-C bonds and even the complete removal of SiC atoms. Furthermore, the removal of C atoms is more difficult than the removal of Si atoms. It is found that the removal of Si atoms largely influences the removal of C atoms. The removal of Si atoms can destroy the lattice structure of the substrate surface, leading the neighboring C atoms to be bumped or even completely removed. Our research shows that the material removal during SiC CMP is a comprehensive result of different atomic-level removal mechanisms, where the formation of Si-O-Si interfacial bridge bonds is widespread throughout the SiC polishing process. The Si-O-Si interfacial bridge bonds are the main removal mechanisms for SiC atoms. This study provides a new idea for improving the SiC removal process and studying the mechanism during CMP.

Effect of Delignification Method on the type of Cellulose Water Hyacinth (Eichornia crassipes) as a Material for Sustainable Sodium-Ion Battery Technology

Abstract Biopolymers developed for solid electrolyte materials of sodium-ion batteries are of great interest these days. The main precursor in the form of cellulose biopolymers has been successfully isolated from water hyacinths (Eichornia crassipes). The first stage is maceration using 2% NaOH to produce cellulose-Iα and Ethanol 60% to produce cellulose-Iβ by hydrothermal reaction process at 150 °C and continued at the bleaching stage with H2O2 solution at 50 °C until it changes color. Then the sample is washed to a neutral pH and dried in an oven at 60 °C. Cellulose-Iα yields were obtained with a yield of 33.98% and cellulose-Iβ of 39.11%. The cellulose-I that has been obtained is modified to obtain cellulose-II type by mercerization method, where cellulose-I type is reacted with 20% NaOH for 5 hours. The mixture is then washed to neutral and dried. Cellulose-II yield was obtained with a yield of 69.21%. Samples were characterized by XRD, FTIR, and SEM. The cellulose content of hyacinths before delignification was 36.69%. The cellulose content of hyacinths after delignification for cellulose-Iα and cellulose-Iβ types was 64.26% and 48.58% respectively. FTIR analysis proved the presence of hydroxyl and carboxyl functional groups in hyacinth cellulose. XRD analysis showed that all three samples were identified with cellulose-Iα, cellulose-Iβ, and cellulose-II amorphous structures with a crystallinity index of 28.62% and the largest crystallite size based on the hkl field (121) of cellulose-Iβ type samples was ~10 nm. SEM analysis shows that cellulose-Iα, cellulose-Iβ has a slim fiber diameter size and straight, smooth surface and microfibrils around the fiber. While cellulose-II shows visualization of a diameter that looks larger and twisted, the surface is rough and there are no microfibrils around the fibers.

Efficient and promising oxidative desulfurization of fuel using Fenton like deep eutectic solvent

Oxidative desulfurization (ODS) has emerged as a prominent technique for the removal of sulfur compounds from fuels, aiming to comply with stringent environmental regulations and minimize sulfur dioxide emissions. Herein, Fenton-like deep eutectic solvents (DESs) were synthesized as a catalyst and reaction medium and their application for the ODS process was investigated. The study encompassed the optimization of DES composition, reaction conditions, and the influence of different parameters on the desulfurization efficiency. The experimental findings demonstrated that the Fenton-like DES exhibited outstanding catalytic activity in the oxidative desulfurization of fuel. The optimized conditions involved conducting the reaction at room temperature for 2.5 h, using 200 mg of the prepared DES (HNFM-FeCl4) as both the extraction solvent and catalyst. An oxidant-to-sulfur (O/S) ratio of approximately 3:1 was maintained, with a 30 wt% H2O2 solution utilized as the oxidant. The analysis of the reaction products using GC–MS revealed a remarkable yield of 98% for dibenzothiophene sulfone. The DES provided a suitable medium for the reaction, enhancing the solubility and availability of sulfur compounds. The iron catalyst, in the presence of hydrogen peroxide, facilitated the oxidation of sulfur-containing compounds to their corresponding sulfones, which can be easily separated from the fuel phase. The DES catalysts exhibited stability and recyclability, making them suitable for practical applications in fuel desulfurization processes.

Piezo-photocatalytic synergetic for H2O2 generation via dual-pathway over Z-scheme ZIF-L/g-C3N4 heterojunction

The constructed ZIF-L/g-C3N4 piezo-photocatalytic system showed exceptional H2O2 production yield. It was primarily attributable to the matched Z-scheme band alignments and the forceful piezoelectric field formed between g-C3N4 and ZIF-L, which was favor of reducing the energy barrier of electron excitation and directional transferring of photo-generated charge carriers. Meanwhile, the composition between ZIF-L and g-C3N4 can alter the H2O2 generation mechanism from single-pathway to dual-pathway. Thus, this mutual promotion significantly elevated the catalytic H2O2 production rate to 1.45 mmol g−1 h−1 without any contaminative scavenger. The catalytically produced H2O2 solution can be used to achieve ultrafast degradation of organic pollutants with 100% efficiency through homogeneous Fenton reaction within tens of seconds. The mediating multi-roles of natural organic matter (NOM) in regulating the H2O2 production were systematically investigated. Finite-element-method (FEM) simulations and density functional theory (DFT) calculations conjointly revealed the constructed piezo-photocatalytic system not only markedly accelerated separation of charge carriers, but also facilitated the activation of vital intermediates (O2*, OOH* and *OH) for H2O2 synthesis, which were the rate-determining steps for oxygen reduction reaction (ORR) and water oxidation reaction (WOR). This study will provoke the rational design of MOFs-based dual-pathway materials for piezo-photocatalytic H2O2 generation and follow-up applications.

An optimisation study for leaching synthetic scheelite in H2SO4 and H2O2 solution

ABSTRACT Tungsten production primarily relies on scheelite, a secondary resource due to its complex ore composition and lower grade compared to high-grade wolframite. Synthetic scheelite gains significance for its low impurity content and accessibility in ongoing laboratory-based investigations. Recent advancements offer a feasible environment-friendly leaching method using a mixed solution of H2SO4 and H2O2 under normal pressure and moderate temperatures. However, comprehensive research on this novel method is lacking, emphasising the need for collaborative exploration and operational optimisation. The present work is to provide insights and improvements in reagent usage to promote economic and environmental sustainability. A detailed investigation into the thermal decomposition process was also conducted without compromising leaching efficiency. The findings suggest the potential for eco-friendly lixivium recycling with reduced levels of chemicals, decreasing operational costs. Notably, optimising the thermal decomposition duration to 6 hours at an L/S (mL/g) ratio of 10 enhances H2WO4 crystallization. Furthermore, experiments without H2SO4 supplementation highlight the system's optimisation potential. Finally, the leaching process was optimised by decreasing H2SO4 concentration to 1 mol/L from 3 mol/L, increasing the temperature to 60°C, and extending the leaching duration to 120 minutes. This leads to a cost-effective synthetic scheelite leaching process with environmental benefits.

Synthesis and Assembly of Photoresponsive Colloidal Tubes.

Inspired by the sophisticated multicomponent and multistage assembly of proteins and their mixtures in living cells, this study rationally designs and fabricates photoresponsive colloidal tubes that can self-assemble and hybrid-assemble when mixed with colloidal spheres and rods. Time-resolved observation and computer simulation reveal that the assembly is driven by phoretic attraction originating from osmotic pressures. These pressures are induced by the chemical concentration gradients generated by the photochemical reaction caused by colloidal tubes in a H2O2 solution under ultraviolet (UV) irradiation. The assembled structure is dictated by the size and shape of the constituent colloids as well as the intensity of the UV irradiation. Additionally, the resulting assembly can undergo self-propelled motion originating from the broken symmetry of the surrounding concentration gradients. This motion can be steered by a magnetic field and used for microscale cargo delivery. The study demonstrates a facile synthesis method for colloidal tubes and highlights their unique potential for controlled, hierarchical self-assembly and hybrid-assembly.

Theoretical and experimental studies of NO removal in alkaline H2O2 system

NO in flue gas is one of the atmospheric pollutants, and it is necessary to study effective NO removal technology. It was identified that the alkaline H2O2 system achieved over 98 % NO removal efficiency with a gas–liquid contact time of 3 s in this paper. This paper investigates the mechanism of NO removal in alkaline H2O2 solution through both experimental and theoretical calculations. The results reveal the NO removal process can be divided into three phases by the NaOH/H2O2 molar ratio. (1) The ∙O2– dominated phase, where trace metal Fe catalyzes ∙O2– radical generation from H2O2 as Fe (OH)2+, reacting primarily with NO to form ONOO–. The energy barrier for this process is1.299 kcal/mol, with a reaction rate constant of 9.12 E + 11 s-1M−1. (2) The HO2– dominated phase, HO2– was generated through OH– and H2O2 neutralization, which converts NO to NO2 and regenerating OH–. The energy barrier for HO2– reacting with NO is 3.833 kcal/mol, and the reaction rate constant is 2.07E + 10 s-1M−1. (3) The O22– dominated phase, O22– was a further ionization of HO2– and converting NO to NO2– directly. The energy barrier for this process is 7.079 kcal/mol, and the reaction rate constant is 1.49 E + 08 s-1M−1.

Selective SERS Detection of TATB Explosives Based on Hydroxy-Terminal Nanodiamond-Multilayer Graphene Substrate.

Selective surface-enhanced Raman scattering (SERS) detection of target explosives with good reproducibility is very important for monitoring soldiers' health and ecological environment. Here, the specific charge transfer pathway was constructed between a stable nanodiamond-multilayer graphene (MGD) film substrate and the target explosives. Two-step wet chemical oxidation methods of H2O2 (30%) and HNO3 (65%) solutions were used to regulate the terminal structure of MGD films. The experimental results showed that the hydroxyl (-OH) functional groups are successfully modified on the surface of MGD thin films, and the MGD-OH substrates having good selectivity for 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) explosive in mixed solutions of the TATB, 2,2-dinitroethene-1,1-diamine, 2,4,6-trinitrotoluene, and 1,3,5-trinitroperhydro-1,3,5-triazine explosives compared with MGD substrates were demonstrated. Finally, first-principles density functional theory simulations revealed that the SERS enhancement of the MGD-OH substrate is mainly attributed to the transferred electrons between the -NO2 groups of TATB and the -OH groups of the MGD-OH substrate.

Dual-responsive solvatochromic sensor for simultaneous detection and mechanism of Cr(III) and Co(II) cations by a new N2O4-donor tetrabenzodiaza-crown ether Macrocyclic ligand anchored to dipyridine moieties

The present study describes the chemosensing capability of an N2O4-donor tetrabenzodiaza-crown ether macrocyclic ligand derivatized by two pyridine side arms to afford the flexible macrocyclic ligand, 5,20-bis(pyridin-4-ylmethyl)-5,6,12,13,19,20,26,27octahydrotetrabenzo [e,i,o,s][1,4,11,14]tetraoxa[7,18]diazacycloicosine (PMHBOA). A selective colorimetric behavior of PMHBOA for the prompt detection of Cr(ΙΙΙ) and Co(ΙΙ) can be observed with naked eyes. The 1H, 13C{H} NMR, and infrared spectroscopy disclosed the ligand binding capability for selective metal ions, ascribed to a 1:1 complex formation with Cr(III) and Co(II) cations in isopropanol. The limit of detection (LOD) values were calculated as 580 and 850 nM for Cr(ΙΙΙ) and Co(ΙΙ), respectively, accompanied with suitable LOQs as 1.95 µM for Cr(III) and 2.85 µM for Co(II), respectively. The reusability was confirmed in the presence of ethylenediaminetetraacetic acid (EDTA). Moreover, a TLC-based fabricated paper strip successfully applied PMHBOA as a chemosensor for synchronous visible detection of Cr(III) and Co(II) in their alcoholic solution. Meanwhile, the observed color change along with the turn-off fluorescent of PMHBOA guaranteed a felicitous choice of candidate for Cr(III) in the presence of other library metal ions in isopropanol:H2O (9/1 v/v) solution. A fast separation test on the filter paper, impregnated with PMHBOA, was also employed to separate Cr(III) and Co(II) cations from aqueous solutions by recording UV–vis spectra. The 1H NMR spectroscopy supported the macrocycle ring and side arms as the parallel coordination site of PMHBOA with Cr(III) and Co(II).

Occurrence of Cassava (Manihot esculenta) Leaf Spot Disease Caused by Diaporthe ueckeri in China.

Cassava (Manihot esculenta) is a perennial crop of the family Euphorbiaceae, widely cultivated due to its phytopharmacological and economic values in China. In November 2022, a leaf spot disease on cassava was observed in Zhanjiang, Guangdong, China (21.17° N, 110.18° E), with 100% disease incidence. About 80 % of leaves were covered with spots on the infected plants. Typical symptoms initially appeared as irregular water-soaked lesions that became brown and whitish with the progress of the disease, lesions gradually expanded and coalesced, causing leaf withering, drying and final fall. Tissues (4 to 5 mm) were excised from the margin of lesions, sterilized in 3% H2O2 solution for 3 min, rinsed three times with sterile water, placed on potato dextrose agar (PDA) medium (containing 50mg/L penicillin), and incubated at 25-28 °C. Ten single hypha isolates with similar morphology were obtained and further purified as single conidium subcultures. The colony was grey whitish with sparse aerial mycelium and colony diameter reached 70.4 mm after four days incubation at 25-28℃ in the dark. Black pycnidia occurring as clusters were spherical or irregular, erumpent at maturity, often with a creamy whitish, conidial cirrus extruding from ostiole after 30-days incubation. Conidiophores were hyaline, smooth, unbranched. Alpha conidia were bi-guttulate, hyaline, ellipsoidal, aseptate, with dimensions of 5.1~7.5×1.9~3.4µm (mean 6.2×2.8 µm, n>50). Beta conidia were abundant, filiform, hyaline, smooth, curved in a hooked shape, with a truncate base and dimensions of 18.5-26.4 × 0.6-1.2μm (mean 23.4 × 1.0 μm, n= 40) . Gamma conidia were not observed. The morphological characteristics were similar to those of Diaporthe ueckeri (Udayanga et al. 2015). The internal transcribed spacer (ITS) region, large subunit (LSU) rRNA sequence, actin (ACT), calmodulin (CAL), histone H3 (HIS), translation elongation factor 1-alpha (TEF1-α), and β-tubulin (TUB) genes of a representative isolate CCAS-MS-6 (ACCC 35497) were amplified and sequenced using primer pairs: ITS5/ITS4, LR0R/LR5, ACT-512F/ACT-783R, CAL228F/CAL737R, CYLH3F/ H3-1b, EF1-728F/ EF1-986R and Bt2a/Bt2b (Gao et al 2017；Udayanga et al 2014). All sequences were deposited in GenBank (OR361671, OR361672, and OR365605-9). BLAST search showed high similarities with sequences of Diaporthe ueckeri (Tab 1). Maximum likelihood analyses of the concatenated data of CAL, HIS, ITS, TEF and TUB using Mega 11 placed CCAS-MS-6 in the D. ueckeri clade. Thus, the fungus was identified as D. ueckeri. Three one-year old healthy plants were used for pathogenicity tests in pots. Two 15-day old leaves of each plant were cleaned with 75% alcohol, three sites on each leaf were wounded, and sites on one of the leaf were covered with fungal plugs from 15-day-old cultures on PDA, and sites on the other leaf with PDA plugs as a control. All plants were kept at ambient temperature (about 28℃) and covered with plastic bags containing sterile wet cotton to maintain the humidity. Seven days after inoculation, all inoculated sites showed symptoms of necrosis, while control sites showed no symptoms. The same fungus identified on the basis of morphological and molecular criteria was reisolated from symptomatic inoculated leaves. In China, D. ueckeri had been reported to cause diseases on Eucalyptus citriodora, Camellia sinensis, and Michelia shiluensis (Gao et al 2016; Liao et al 2023; Yi et al 2018), this is the first report on M. esculenta. The definition of the disease etiology is a prerequisite to develop effective management strategies.

Portable T-2 toxin biosensor based on target-responsive DNA hydrogel using water column height as readout

T-2 toxin, a hazardous mycotoxin often present in cereals and products based on cereals, poses a substantial risk to humans and animals due to its high toxicity. The development of uncomplicated, quick and highly sensitive methods for detecting T-2 toxin is imperative. In this work, a portable sensing system was constructed using water column height as a readout device in combination with a controlled release system, which allows for an accurate quantitative analysis of T-2 toxin without the need for expensive instrumentation or skilled technicians. Hyaluronic acid (HA) hydrogel was constructed by double cross-linked DNA/aptamer hybrids with polyethyleneimine (PEI) and embedded with platinum nanoparticles (Pt NPs). The aptamer specifically bound to T-2 toxin in its presence, resulting in the disruption of the hydrogel and subsequent release of the Pt NPs. These Pt NPs were later mixed with a solution of H2O2 in a confined reaction flask, leading to the decomposition of H2O2 into O2. A glass capillary tube containing a column of red water had been inserted into the cap of the reaction flask, and the low solubility of O2 led to an increase in pressure within the reaction unit, causing the red water column to rise. There is a good linear correlation between the height of the capillary liquid level and the T-2 toxin concentration in the range of 20 ng/mL to 6 μg/mL. The system has been successfully used to detect T-2 toxin in samples of barley tea and corn.