Low Stability Research Articles

Nanozyme-catalyzed and zwitterion-modified swabs based for the detection of Listeria monocytogenes in complex matrices

In recent years, nanozymes have been widely used in the field of biosensing and food safety testing due to their advantages of low cost, high stability, easy modification and adjustable catalytic activity. However, how to reduce the signal interference generated by reducing substances, macromolecules and colored substances in the food matrix in nanozymes-based colorimetric sensing is still a major challenge. In this paper, using Listeria monocytogenes as a model analyte, sodium sulfonyl methacrylate (SBMA) polymers were modified onto cotton swabs by photothermal polymerization and combined with Listeria monocytogenes-specific aptamer (Apt1) to prepare swabs that can specifically capture and isolate Listeria monocytogenes from complex matrices (SBMA/Apt1 cotton swab). In addition, in combination with the inhibitory effect of the aptamer (Apt2) on the oxidase activity of Mn3O4 NPs, a colorimetric biosensor based on nanozymes that can quantitatively, sensitively, and specifically identify Listeria monocytogenes in food products was constructed. The results showed that the colorimetric signal of the method was linear with the concentration of Listeria monocytogenes in the range of 2.83–2.83 × 105 CFU/mL, and the limit of detection was 2.64 CFU/mL, which can be used for the detection of Listeria monocytogenes in complex environments and food samples.

Superionic halide solid electrolyte Li1.7Zr0.7Ta0.3Cl6 for durable all-solid-state lithium batteries

Zirconium-based halide solid electrolyte, Li2ZrCl6, with low raw-material cost and high oxidative stability is a promising candidate for next-generation energy storage devices. However, the low ionic conductivity hinders its practical applicability. Herein, we report a new zirconium-based superionic conductor based on high-valence Ta5+ doping strategy. The optimized Li1.7Zr0.7Ta0.3Cl6 (LZTC) exhibits excellent ionic conductivity of 1.42 mS cm-1 at 25 °C. Moreover, it can be further increased up to 1.68 mS cm-1 with a low activation energy of 0.28 eV by slightly tuning Li+ concentration. In addition, LZTC possesses a big compact density of 2.67 g cm-3 under 250 MPa and is compatible with 4V-class cathodes. Density function theory (DFT) and bond valence site energy (BVSE) calculations reveal Ta5+ substitution significantly reduces the migration energy barrier of lithium ions due to the distortions and defects of local structural environment. The assembled all-solid-state batteries with Li1.7Zr0.7Ta0.3Cl6 as electrolyte and scNCM811 as cathode show excellent cycling performance for 600 cycles at 1C with a high-capacity retention of 85.7%.

An Assessment of the Mechanical Deformation Behavior of Three Different Clear Aligner Materials: A Digital Image Correlation Analysis

Introduction: The present study aimed to investigate the deformation behavior of three different clear aligner systems, CA® Pro+ Clear Aligner (Scheu Dental, Iserlohn, Germany), Taglus Premium (Taglus Company, Mumbai, India), and Spark Trugen (Ormco Corp., Orange, CA, USA), under compression testing, using the digital image correlation (DIC) technique. Materials and Methods: A total of 15 patients were treated with each of the three aligner systems, resulting in 45 sets of aligners. Each aligner set was fixed on the 3D-printed dental arches and then in an articulator. Then, the samples were subjected to occlusal forces using a purpose-built test stand to allow for controlled force application and precise displacement determination. The DIC technique was used for capturing the deformation behavior, providing detailed strain and displacement fields. Statistical analysis was performed using one-way ANOVA and Bonferroni post hoc tests with a significance of 0.05. Results: The results indicate that the Spark system exhibited the most substantial rigid displacement. Furthermore, the elastic deformation values of the Spark and Taglus systems were significantly higher than those of the CA Pro+ system (p > 0.05). Conclusions: The Spark Trugen clear aligner system demonstrated a lower stability to rigid displacement and elastic deformation under compression testing compared to the Scheu CA® Pro+ Clear Aligner and Taglus Premium. All three tested clear aligner systems showed an increased resistance to elastic displacement and rigid deformation in the mandibular arch.

Stability of retained austenite and its effect on tensile properties and hole expansion performance of high-strength steel

Medium manganese steel has a ferritic matrix with retained austenite as the secondary phase at room temperature (RT). The effect of the transformation-induced plasticity (TRIP) of retained austenite on steel has earlier been found to result in an excellent combination of high strength and ductility, making it a promising candidate as a third-generation advanced high-strength steel (AHSS) for automotive applications. Therefore, extensive research has recently been conducted with the aim to increase the amount of retained austenite in steel, thereby enhancing the strength and ductility of the steel. However, an increase in the amount of retained austenite can be detrimental to the HER, which is due to its low mechanical stability and the transformation to martensite when forming holes by punching. However, there has been relatively little research on this topic.The impact of the mechanical stability of retained austenite on the tensile properties and hole expansion ratio (HER) of high-strength medium-Mn steel have been investigated in the present study. Samples were prepared using one-step austenite-reverted-transformation (ART) annealing, which resulted in steel with 24.7 % retained austenite and moderate mechanical stability. The steel showed also an excellent combination of strength and ductility. Samples were also prepared using two-step annealing, which showed a positive effect on the HER of the steel, regardless of the processing method used for the formation of a central hole on the samples. However, it slightly reduced the ductility of the steel. For all these samples, the impact of the retained austenite on the HER was found to be closely related to its mechanical stability and content in the steel.Retained austenite with poor stability transformed into hard martensite during the punching processing of holes. In contrast, the retained austenite with a relatively high stability showed a positive effect during the whole hole expansion deformation process. It decreased the stress concentration and, thereby, improved the HER. Thus, the present study has found that it is of the greatest importance to improve the stability of the retained austenite in high-strength medium-Mn steel, and to suppress its transformation to martensite during the punching of holes in the steel.

Ohmic Contact Resistance in SiC Diodes with Ti and NiSi P<sup>+</sup> Contacts

Ohmic contacts play a major role in the signal transfer between the semiconductor device and the external circuitry. One of the main technological issues to develop high-performance SiC-based devices is the control of metal/SiC contact properties to fabricate low resistance and high stability SiC Ohmic contacts to p-type SiC. This is mostly due to intrinsic SiC characteristics like large work function, low dopant activation for p-type materials and low hole mobility. These limits are even more emphasized in SiC JBS or MPS diodes, where Schottky and Ohmic contacts on the P doped regions embedded in the active area to improve surge ruggedness are usually formed by using the same metallization process. This naturally results either in a high Schottky barrier height in the Schottky contact with consequent increase of the conduction loss at low currents or in a poorly conductive Ohmic contact, leading to reduced IFSM capability. Therefore, the optimization and control of the process parameters like for example the P+ doping concentration peak underneath the metallization layer and the annealing process temperatures is crucial to obtain a good Ohmic contact and enhance the device´s robustness against surge current.

One-Pot In Situ Construction of a Highly Stable Acylhydrazone-Derived Dy9 Cluster with Photodynamic Sterilization Property.

The extremely low stability of lanthanide clusters with precise structures and nanometer dimensions in aqueous solutions limits their application in the field of photodynamic sterilization. In this study, an hourglass-shaped nine-nucleated Dy9 cluster (1) with excellent light-driven reactive oxygen species (ROS) generation ability and photodynamic sterilization property was constructed using acylhydrazone multidentate chelating ligands obtained via an in situ reaction. The eight chelating ligands were distributed outside cluster 1, tightly wrapping the cluster core, thus preventing solvent molecules from attacking the cluster nucleus and ensuring the stability of cluster 1 in solution, which was demonstrated via X-ray diffraction and high-resolution electrospray ionization mass spectrometry (HRESI-MS). Time-dependent HRESI-MS monitoring of the self-assembly process of cluster 1 allowed two possible self-assembly mechanisms. The heavy atom effect of multiple Dy(III) ions in the Dy9 cluster enhanced the ISC pathway through spin-orbit coupling, promoting energy transfer from the excited singlet state (S1) to the triplet state (T1), which was stabilized, inducing the generation of more ROS. Cluster 1 showed a remarkable sterilization effect due to the generation of abundant ROS under light irradiation conditions. To our knowledge, this is a rare instance of lanthanide clusters with photodynamic sterilization, providing new horizons for the construction of fast and efficient sterilizers.

Stability and gastrointestinal digestion behaviour of theaflavins encapsulated in W/O Pickering emulsions

Theaflavins (TFs) are naturally bioactive compounds with low stability and poor bioavailability. In this study, the stability of TFs during storage at 25 °C for 21 d and thermal treatments at 65 °C, 85 °C and 105 °C for 0.5–4 h of water in oil (W/O) Pickering emulsions composed of TFs (0–9 mg/g), ursolic acid, oil and water were investigated. The TFs incorporation at 9 mg/g had the smallest droplet size and the highest G′ and G″ values. After storage for 21 days and thermal treatment at 105 °C for 4 h, the TFs retention in emulsions (9 mg/g) were 1.2-fold and 1.4-fold higher than aqueous solution, respectively, which might be attributed to the encapsulation of TFs in water droplets. During digestion, TFs emulsions provided a greater surface area for lipid digestion and led to a higher release of free fatty acids than emulsions without TFs. Moreover, there was sustained release of TFs in the emulsion, resulting in significantly enhanced TFs bioaccessibility (57.8 ± 9.2%) compared with aqueous solution (17.7 ± 1.1%) and Oil-Water mixture (32.6 ± 2.3%) after intestinal digestion. This study provides insights for food industry in designing W/O emulsion systems for the delivery of hydrophilic bioactive components.

Potential interventions and interactions of bioactive polyphenols and functional polysaccharides to alleviate inflammatory bowel disease – A review

Inflammatory bowel disease is a multifaceted condition that is influenced by nutritional, microbial, environmental, genetic, psychological, and immunological factors. Polyphenols and polysaccharides have gained recognition for their therapeutic potential. This review emphasizes the biological effects of polyphenols and polysaccharides, and explores their antioxidant, anti-inflammatory, and microbiome-modulating properties in the management of inflammatory bowel disease (IBD). However, polyphenols encounter challenges, such as low stability and low bioavailability in the colon during IBD treatment. Hence, polysaccharide-based encapsulation is a promising solution to achieve targeted delivery, improved bioavailability, reduced toxicity, and enhanced stability. This review also discusses the significance of covalent and non-covalent interactions, and simple and complex encapsulation between polyphenols and polysaccharides. The administration of these compounds in appropriate quantities has proven beneficial in preventing the development of Crohn's disease and ulcerative colitis, ultimately leading to the management of IBD. The use of polyphenols and polysaccharides has been found to reduce histological scores and colon injury associated with IBD, increase the abundance of beneficial microbes, inhibit the development of colitis-associated cancer, promote the production of microbial end-products, such as short-chain fatty acids (SCFAs), and improve anti-inflammatory properties. Despite the combined effects of polyphenols and polysaccharides observed in both in vitro and in vivo studies, further human clinical trials are needed to comprehend their effectiveness on inflammatory bowel disease.

A novel dual-stage failure criterion based on forming limit curve for uncured GLARE

Forming limit curve (FLC) is an essential criterion for evaluating the formability of fiber metal laminates (FMLs) in mass fabrication. However, conventional methodologies are unable to predict inner fiber failure, very sensitive to wrinkling defects, resulting in low measurement accuracy and stability. Hence, a novel dual-stage failure criterion considering the progressive failure of fiber and metal layers has been developed and validated by utilizing a notch-pattern sample and forming of typical thin-walled structure, with four typical categories of glass laminate aluminum reinforced epoxy (GLARE). The Nakajima tests of a series of notch-pattern and conventional pattern specimens with different widths were conducted in this study, demonstrating the superiority of wrinkling and delamination prevention of the notch-pattern by enhancing 22.84 % stress triaxiality and reducing 39.51 % compress strain in the edge area. Notably, punch reaction force and strain field analyses unveiled a mutation phenomenon indicative of premature fiber failure while the aluminum remained intact, which was also verified by numerical and interrupted methods. Furthermore, the acoustic emission in-situ method was adopted to monitor the progressive damage evolution of uncured GLARE in the Nakajima test, providing solid support for the occurrence of fiber failure at the mutation site. Leveraging these mutations, a list of dual-stage forming limit curves was devised to quantify the progressive damage behavior of uncured GLARE under biaxial tensile conditions. Finally, the practical application of this novel dual-stage forming limit curve methodology was demonstrated in the manufacturing process of a box-shaped part, serving as a proof of concept for its effectiveness. This study offers a foundational guideline for characterizing the intrinsic failure mechanisms of fiber metal laminates, particularly internal fiber failure under various strain conditions, thereby enhancing predictive accuracy.

Constructing Hierarchical Zeolites with Highly Complete Framework via Controlled Desilication.

Desilication in alkaline medium has been widely used in construction of hierarchical zeolites for industrially relevant catalytic processes. The built of hierarchy in zeolites, especially with low aluminum stability or high Si/Al ratio, often suffers from uncontrolled destruction of zeolitic framework, accompanied by a significant loss of microporous domains and intrinsic acidity after desilication. Here, we report a novel and simple methodology for preparation of hierarchical zeolites with highly complete framework and minimum sacrifice of microporosity and acidity. The pre-impregnated amines in zeolite micropores act as inner pore-directing agents (iPDAs), largely protecting the zeolitic framework and moderating the silicon extraction during the alkaline treatment. The resulting hierarchical zeolites exhibit high crystallinity, tunable hierarchy, stable framework, and well-preserved acidity, endowing them with significantly improved mass transport properties and enhanced activities in catalytic conversion of methanol or furfural.

Vanadium-Based Metal-Organic Frameworks with Peroxidase-like Activity as a Colorimetric Sensing Platform for Direct Detection of Organophosphorus Pesticides.

Colorimetry based on the bioenzyme inhibition strategy holds promising application prospects in the field of organophosphorus pesticide (OPs) detection. However, overcoming the challenges of the high cost and low stability of bioenzymes remains crucial. In this study, we successfully synthesized a peroxidase vanadium-based metal-organic framework (MOF) nanozyme named MIL-88B(V) and employed its mediated bioenzyme-free colorimetric strategy for direct OPs detection. The experimental results demonstrated that MIL-88B(V) exhibited a remarkable affinity and a remarkable catalytic rate. When the OPs target is added, it can be anchored on the MOF surface through a V-O-P bond, effectively inhibiting the MOF's activity. Subsequently, leveraging the advantages of smartphones such as convenience, speed, and sensitivity, we developed a paper sensor integrated into a smartphone for efficient OPs detection. The as-designed nanozyme-based colorimetric assay and paper sensor presented herein offer notable advantages, including affordability, speed, stability, wide adaptability, low cost, and accuracy in detecting OPs, thus providing a versatile and promising analytical approach for real sample analysis and allowing new applications of V-based MOF nanozymes.

The role of polymer gel electrolyte infiltration for enhancement of capacitance and cycle stability

With the increasing application of electronic materials in various fields such as flexible electronic textiles, wearable and portable gadgets, aerospace and aircraft systems etc., the demand for clean high-power energy storage devices is also increasing rapidly. To date, the application of market available supercapacitors has not met the energy expectations in the range of market leading Li-ion batteries (LIBs) due to their unreliable mechanical flexibility, electrolyte leakage, low voltage application, low capacity, low cycle stability and moderate rate-capability. Inappropriate utilization of the maximum porosity of the electrode material and inefficient activities of the electrode/electrolyte interface are major challenges for present supercapacitor development. In this work, for the first time, the role of polymer gel electrolyte infiltration to improve the electrochemical performance of a supercapacitor has been explicitly studied and investigated. It has been observed that 1-Ethyl-3- Methylimidazolium bis(trifluoromethylsulfonyl)imide [EMIM][TFSI] ionic liquid electrolyte embedded in Polypropylene Carbonate (PPC) and Polycarbonate (PC) polymer matrix polymer gel electrolyte (PGE) showed excellent supercapacitive performance at high voltage window 2.6 V by delivering maximum total capacitance of 5.81 F and maximum energy density 10.9 Wh kg-1 at 30 mA current (0.06 A g-1). Regular infiltration of the polymer gel electrolyte inside the electrode material is also observed during long cycle operation of 10,000 cycles. Infiltration of electrolyte ions into the pores of electrode materials plays a significant role in increasing capacitance and cycle Stability. These results highlight the potential of this novel high-voltage polymer gel electrolyte for future high-power energy storage device applications.

Enhancement of Antimicrobial Function by L/D-Lysine Substitution on a Novel Broad-Spectrum Antimicrobial Peptide, Phylloseptin-TO2: A Structure-Related Activity Research Study.

Antibiotic resistance poses a serious threat to public health globally, reducing the effectiveness of conventional antibiotics in treating bacterial infections. ESKAPE pathogens are a group of highly transmissible bacteria that mainly contribute to the spread of antibiotic resistance and cause significant morbidity and mortality in humans. Phylloseptins, a class of antimicrobial peptides (AMPs) derived from Phyllomedusidae frogs, have been proven to have antimicrobial activity via membrane interaction. However, their relatively high cytotoxicity and low stability limit the clinical development of these AMPs. This project aims to study the antimicrobial activity and mechanisms of a phylloseptin-like peptide, phylloseptin-TO2 (PSTO2), following rational amino acid modification. Here, PSTO2 (FLSLIPHAISAVSALAKHL-NH2), identified from the skin secretion of Phyllomedusa tomopterna, was used as the template for modification to enhance antimicrobial activity. Adding positive charges to PSTO2 through substitution with L-lysines enhanced the interaction of the peptides with cell membranes and improved their antimicrobial efficacy. The analogues SRD7 and SR2D10, which incorporated D-lysines, demonstrated significant antimicrobial effects against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) while also showing reduced haemolytic activity and cytotoxicity, resulting in a higher therapeutic index. Additionally, SRD7, modified with D-lysines, exhibited notable anti-proliferative properties against human lung cancer cell lines, including H838 and H460. This study thus provides a potential development model for new antibacterial and anti-cancer drugs combating antibiotic resistance.

4-amino-5-(pyridin-4-yl)-4H-1,2,4-triazole-3-thiol as potent antimicrobial agent: Synthesis, X-ray, antimicrobial activity and computational studies

In this work, 1,2,4-triazole derivative derived from Isoniazid namely, 4-amino-5-(pyridin-4-yl)-4H-1,2,4-triazole-3-thiol (APTT) was synthesized and fully characterized by FT-IR, 1H NMR, 13C NMR, HRMS-ESI, and single crystal X-ray diffraction. The optimized structures of monomer, dimer and tetramer of APTT with the hybrid B3LYP/6-311++G** method explain the inter and intra-molecular interactions observed experimentally by X-ray diffraction. The presence of tetramer justify the strong IR bands observed in the 2400 and 1800 cm-1 region. The IR spectrum was completely assigned and the scaled force constants reported by using the scaled quantum mechanical force field (SQMFF) approach and the Molvib program. Good correlations between experimental and predicted NMR and UV-Vis spectra are obtained. Both NBO and AIM calculations reveal the inter and intra-molecular interactions and the low stability of APTT in solution while the gap values suggest its low reactivity in the same medium. The different studies reveal the important role of intra and inter-molecular interactions in the stability and reactivity of APTT in the two media. Also, antimicrobial activity of APTT was evaluated against common bacteria and fungi as S. aureus, S. pyrogenes, E. faecalis, V. parahaemolyticus, P. aeruginosa, S. enteritidis, S. cerevisiae, C. albicans, C. tropicalis, C. glabrata, and C. parasilosis. The antimicrobial activity results showed that APTT exhibited both bactericidal and fungicidal activity against all the microbial strains tested. These two effects underline the versatility of the title compound in combating a broad spectrum of microbial infections.

Investigating the safety of solid/liquid hybrid electrolyte lithium-ion battery: A comparative study with traditional LIBs under abuse condition

Lithium-ion battery (LIB) with solid‒liquid hybrid electrolyte is an important milestone in the development of all-solid-state battery (ASSB) to achieve higher energy density. In-depth understanding of the safety of solid‒liquid hybrid electrolyte battery (HS-LIB) is investigated for the first time: a detailed analysis and comparison of the possibility and severity of thermal runaway (TR) of HS-LIB and LIB are performed under typical abuse conditions to further explain the practical safety of HS-LIB in multiple dimensions. Poor thermal safety is identified by the lower self-heating onset temperature Tonset (78 °C) and thermal runaway triggering temperature Ttr (138 °C) of HS-LIB with 100 % state of charge (SOC), as well as higher maximum temperature Tmax (>1200 °C) and 2–3 times maximum temperature rise rate dT/dtmax (349.3 °C/s) higher than LIBs. The significant volume changes of SiOx as an anode material contribute to uneven SEI formation, while the resultant cracks and voids accelerate SEI decomposition prematurely. The lower thermodynamic parameter-apparent activation energy Ea also indicates that the test battery has lower thermal stability, and the comparative results of the TNT-equivalent corroborated the greater thermal hazards. External overheating conditions also results in a lower Ttr (168 °C) and shorter time to thermal runaway ttr (177 s) due to faster heat absorption with dT/dtmax (933.8 °C/s). Self-generation of heat by SE in the temperature range that triggers the main response to TR and the high energy release in a short period of time exacerbate the TR hazard. Worse electrical behavior is proven through lower state of charge (114 %) and higher dT/dtmax (>420 °C/s). Encouragingly, HS-LIB exhibits excellent mechanical safety, due to the double roles of solid-state electrolytes: as an electrolyte and a separator, which avoids internal short-circuits caused by melting of the separator at hot spots. Lower thermal stability with greater hazards is explained by a correlation mechanism analysis and these experimental results can provide some reference for the safe design of ASSB.

Comprehensive Review of Li-Rich Mn-Based Layered Oxide Cathode Materials for Lithium-Ion Batteries: Theories, Challenges, Strategies and Perspectives.

Lithium-rich manganese-based layered oxide cathode materials (LLOs) have always been considered as the most promising cathode materials for achieving high energy density lithium-ion batteries (LIBs). However, in practical applications, LLOs often face some key problems, such as low initial coulombic efficiency, capacity/voltage decay, poor rate performance and poor cycle stability. It seriously shortens the lifespan of lithium-ion batteries and hinder the large-scale commercial application of LLOs. Herein, firstly, the basic theories of LLOs were systematically reviewed, including the structural characteristics, the working mechanism of LLOs, the preparation methods of LLOs (liquid phase co-precipitate method, sol-gel method, hydrothermal synthesis method, solid phase method, low heat solid-phase method, high temperature solid-state method etc.), and electrochemical characteristics of LLOs (first charge discharge characteristics and reversible efficiency, cycling performance, high and low temperature performance and thermal stability etc.). Then, key challenges faced by LLOs were systematically discussed. Finally, the LLOs modification strategies used to address these challenges (element doping, surface modification, defect engineering, structural and morphological control etc.) were elaborated in detail. This important review provides potential insights and directions for further improving the electrochemical performance of LLOs, and provides a necessary theoretical basis for accelerating the large-scale commercial application of LLOs. It possesses important scientific research value and far-reaching social significance.

Evolution Process of Fault Silica Aerogel under High Temperatures: A Molecular Dynamics Approach.

Building fire will seriously threaten human safety. Silica aerogel with low thermal conductivity and thermal stability as fire-retardant material has been widely used in building fireproof structures. However, the natural fragility of silica aerogel will limit its application. In this work, the effects of faults on the thermal stability of silica aerogel are studied by molecular dynamics simulation with large simulation time (20 ns). Additionally, the atomic model of silica aerogel with random faults is built by a straining structure (tensile strains are 10%, 20%, 30%, and 40%). It is found that when the tensile strain is less than 20%, the silica backbone can remain stable. The effects of faults on the thermal stability can be neglected. The silica backbone thermally vibrates during the heating process. However, when the tensile strain is over 30%, it is observed that the faults will enhance the silica backbone merging. Silica aerogel can be stable under 800 K. It is believed that the results of this study will pave the way for the development of fireproof materials.

MOF-derived Mo-doped Co3O4: A hierarchical yeast-like structure for superior carbon monoxide sensing

Carbon monoxide (CO) is one of the most dangerous gases owing to its dual threat, role in global warming, and severe impact on human health. Metal-organic framework (MOF) gas-sensing materials have drawn the interest of many different sectors due to their unique structural characteristics. This study used a solvothermal technique and subsequent annealing to create a hierarchical, yeast-shaped Mo-Co3O4 material from a Co-MOF precursor. The prepared materials have been employed in the development of a CO-detection gas sensor. Gas-sensing experiments revealed that Mo-Co3O4 exhibited significantly improved sensing capabilities compared to pure Co3O4. Notably, at 200 °C, 2 mol% Mo-Co3O4 showed high response levels of about 136 at 100 ppm CO concentrations, approximately 50.4 times higher than pure Co3O4. Furthermore, the Mo-doped material exhibited a low detection threshold, excellent reproducibility, long-term stability, good selectivity, and rapid response and recovery times (78.5/55.3 s). Introducing Mo dopants into the Co3O4 material and the hierarchical yeast-like nanostructure are responsible for these improvements in gas-sensing capability.

Assessment of Accelerated Aging Effect of Bio-Oil Fractions Utilizing Ultrahigh-Resolution Mass Spectrometry and k-Means Clustering of van Krevelen Compositional Space.

Bio-oils contain a substantial number of highly oxygenated hydrocarbons, which often exhibit low thermal stability during storage, handling, and refining. The primary objectives of this study are to characterize the hydroxyl group in bio-oil fractions and to investigate the relationship between the type of hydroxyl group and accelerated aging behavior. A bio-oil was fractionated into five solubility-based fractions, classified in two main groups: water-soluble and water-insoluble fractions. These fractions were then subjected to chemoselective reactions to tag molecules containing hydroxyl groups and analyzed by negative-ion electrospray ionization 21 T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The fractions were also subjected to accelerated aging experiments and characterized by FT-ICR MS and bulk viscosity measurements. Extracting insightful information from ultrahigh-resolution data to aid in predicting upgrading methodologies and instability behaviors of bio-oils is challenging due to the complexity of the data. To address this, an unsupervised learning technique, k-means clustering analysis, was used to semiquantify molecular compositions with a close Euclidean distance within the (O/C, H/C) chemical space. The combination of k-means analysis with findings from chemoselective reactions allowed the distinctive hydroxyl functionalities across the samples to be inferred. Our results indicate that the hexane-soluble fraction contained numerous molecules containing primary and secondary alcohols, while the water-soluble fraction displayed diverse groups of oxygenated compounds, clustered near to carbohydrate-like and pyrolytic humin-like materials. Despite its high oxygen content, the water-soluble fraction showed minimal changes in viscosity during aging. In contrast, a significant increase in viscosity was observed in the water-insoluble materials, specifically, the low- and high-molecular-weight lignin fractions (LMWL and HMWL, respectively). Among these two fractions, the HMWL exhibited the highest increase in viscosity after only 4 h of accelerated aging. Our results indicate that this aging behavior is attributed to an increased number of molecular compositions containing phenolic groups. Thus, the chemical compositions within the HMWL are the major contributors to the viscosity changes in the bio-oil under accelerated aging conditions. This highlights the crucial role of oxygen functionality in bio-oil aging, suggesting that a high oxygen content alone does not necessarily correlate with an increase of viscosity. Unlike other bio-oil categorization methods based on constrained molecule locations within the van Krevelen compositional space, k-means clustering can identify patterns within ultrahigh-resolution data inherent to the unique chemical fingerprint of each sample.

Polyoxometalate-based nanozyme with laccase-mimicking activity for kanamycin detection based on colorimetric assay.

As a kind of aminoglycoside antibiotics, kanamycin (KAN) is widely applied to animal husbandry and aquaculture. However, the abuse of KAN causes the large-scale discharge of it into rivers, lakes and groundwater, which threatens environmental safety and human health. Therefore, it is imperative to develop a method that is applicable to detect KAN in an efficient and accurate way. The colorimetric method based on enzymes provides a feasible solution for the detection of organic pollutants. However, the extensive application of natural enzymes is constrained by high cost and low stability. Herein, a polyoxometalate-based nanozyme, namely [H7SiW9V3O40(DPA)3]·4H2O (SiW9V3/DPA) (DPA = dipyridylamine), is synthesized. As a low-cost nanozyme with high stability compared to natural enzymes, SiW9V3/DPA performs well in laccase-mimicking activity. It can be used to induce chromogenic reaction between 2,4-dichlorophenol (2,4-DP) and 4-aminoantipyrine (4-AP), which generates red products. With the addition of KAN, the color fades. That is to say, KAN can be detected with colorimetric assay in the concentration range 0.1 to 100μM with high selectivity and low limit of detection (LOD) of 6.28μM.Moreover, SiW9V3/DPA is applied to KAN detection in lakeand riverwater and milk with satisfactory results. To sum up, polyoxometalate-based nanozyme is expected to provide a promising solution to the detection of organic pollutants in the aquatic environment.