Latest ArticlesSelenium is one of the important trace elements in the human body. Its deficiency will directly affect human health. With people's attention to health, the content of selenium in food has gradually attracted attention. However, detecting selenium compounds in complex samples remains a challenge. In this work, we built an online heating-reaction device. This device combines the electrospray extraction ionization mass spectrometry (EESI-MS) with the heating reaction device, which can simultaneously detect various selenium compounds in complex liquid samples. Under acidic conditions, the sample was heated and catalyzed by a heating reaction device, so that the SeO32− and O-phenylenediamine (OPD) could generate 1,3-dihydro-2,1,3-benzoselenadiazole. Based on the above reactions, we can detect organic selenium, inorganic selenium and other compounds in liquid samples by organic mass spectrometry. In this experiment, we determined the content of three forms of selenium: selenomethionine (SeMet), l-selenocystine (SeCys(2)), and sodium selenite. The calibration curves for SeMet, SeCys(2), and sodium selenite showed strong linearity within a range of 0.50–50.00 µg/L. The limits of detection (LOD) for the three compounds were 0.22, 0.27, and 0.41 µg/L, respectively. The limits of quantification (LOQ) were 0.68, 0.81, and 1.23 µg/L, respectively. Spiked recoveries at three levels ranged from 98.8% to 106.1%. In addition, this method can simultaneously detect three selenium compounds and three other specific chemical components in tea infusion samples, providing a rapid and efficient method for identifying tea quality.
Photocatalysis is widely regarded as a highly promising sustainable technique for addressing the challenges posed by environmental pollution and energy provision. In recent years, metal-loaded MOFs has become a rising star within the domain of photocatalysis due to its high specific surface area and porosity, adjustable structure, diverse and abundant catalytic components, which has exhibited excellent photocatalytic activity and exhibit great potential in a range of disciplines. In this paper, the principles for evaluating the photocatalytic performance of MOFs-based materials were firstly introduced, and some typical examples were also listed accordingly. Along with this, particular emphasis is paid to the main factors affecting the photocatalytic performance of metal-loaded MOFs. Then the synthesis and design strategies of MOFs loaded metal entities of varying sizes (single atoms, nanoclusters, and nanoparticles), and their applications in photocatalytic CO2 reduction, hydrogen production, photooxidation and photocatalytic hydrogenation were summarized and discussed. Finally, the opportunities and challenges faced in this kind of MOFs-based composites were analyzed from different perspectives. This report is expected to help researchers design and develop high-performance MOFs-based photocatalytic materials.
Inactivation of carbon-based transition metal catalysts, which was caused by electron loss, limited their application in advanced oxidation processes. Therefore, Co and TiO2 double-loaded carbon nanofiber material (Co@CNFs-TiO2) was synthesized in this study. Photocatalytic and chemical catalytic systems were synergized efficiently. Tetracycline was eliminated within 15 min. The degradation rate remained above 90% after five cycles, and the 50% promotion proved the high stability of Co@CNFs-TiO2. The main reactive oxygen species in this system were sulfate radicals, whereas Co and TiO2 represented the active sites of the catalytic reaction. Electrons generated from TiO2 during the photocatalytic process were transferred to Co, which promoted the Co(Ⅲ)/Co(Ⅱ) cycle and maintained Co in a low-valence state, thereby stimulating the generation of sulfate radicals. In this study, the effective regulation of reactive oxygen species in the reaction system was realized. The results provided a guidance for in situ electron replenishment and regeneration of carbon-based transition metal catalysts, which will expand the practical application of advanced oxidation processes.
Catalytic oxidation of soot is of great importance for emission control on diesel vehicles. In this work, a highly active Cs/Co/Ce-Sn catalyst was investigated for soot oxidation, and it was unexpectedly found that high-temperature calcination greatly improved the activity of the catalyst. When the calcination temperature was increased from 500 ℃ to 750 ℃, T50 decreased from 456.9 ℃ to 389.8 ℃ in a NO/O2/H2O/N2 atmosphere. Characterization results revealed that high-temperature calcination can promote the ability to transfer negative charge density from Cs to other metal cations in Cs/Co/Ce-Sn, which will facilitate the production of more oxygen defects and the generation of more surface-active oxygen species. Surface-active oxygen species are beneficial to the oxidation of NO to NO2, leading to the high yield of NO2 exploitation. Therefore, the Cs/Co/Ce-Sn catalyst calcined at 750 ℃ demonstrated higher activity than that calcined at 500 ℃. This work provides a pathway to prepare high efficiency catalysts for the removal of soot and significant insight into the effects of calcination on soot oxidation catalysts.
Quantitative determination of tetracycline (TC) in environment and foods is of great importance, as excessive residues might have negative effects on human health and environmental risks. Herein, a self-powered molecularly imprinted photoelectrochemical (PEC) sensor based on the ZnO/C photoanode and the Fe-doped CuBi2O4 (CBFO) photocathode is developed for the sensitive detection of TC. The photocathodic current can be amplified by the efficient electron transfer caused by the Fermi energy level gap between the photoanode and photocathode. Furthermore, molecularly imprinted polymers (MIPs) at photocathode can selectivity identify the TC templates and thus improve the specificity. Under the optimal conditions, the sensor has a linear range of 10‒2–1.0 × 105 nmol/L, and a limit of detection (LOD) of 0.007 nmol/L (S/N = 3). More crucially, the milk sample detection is carried out using the as-prepared sensor, and the outcome is satisfactory. The research gives us a novel sensing platform for quick and accurate antibiotic (like TC) in environment and food monitoring.
This review covers the structures of diterpenoids, including chain (72), monocyclic (9), labdane-type (67), clerodane-type (127) abietane-type (716), ent-kaurane-type (89), grayanane-type (331), ingenane-type (55), tigliane-type (154), daphnane-type (237), and aconitine-type diterpene alkaloids (265) with rich biological activities reported in 2013–2023. And the drugs in clinical use or under clinical investigation of diterpenoids and leading compounds were summarized.
The rapid development of microfluidic technology has led to the evolution of microdroplets from simple emulsion structures to complex multilayered and multicompartmental configurations. These advancements have endowed microdroplets with the capability to contain multiple compartments that remain isolated from one another, enabling them to carry different molecules of interest. Consequently, researchers can now investigate intricate spatially confined chemical reactions and signal transduction pathways within subcellular organelles. Moreover, modern microdroplets often possess excellent optical transparency, allowing fluorescently labelled, multi-layered, and compartmental droplets to provide detailed insights through real-time, in situ, and dynamic fluorescence imaging. Hence, this review systematically summarizes current methodologies for preparing multicomponent microdroplets and their applications, particularly focusing on fluorescent microdroplets. Additionally, it discusses existing critical challenges and outlines future research directions. By offering a comprehensive overview of the preparation methods and applications of fluorescent microdroplets, this review aims to stimulate the interest of researchers and foster their utilization in more complex and biomimetic environments.
An ionic liquid assisted hydrogel modified silica was synthesized using a one-pot polymerization and physical coating technique and subsequently applied to mixed-mode liquid chromatography. Analytical techniques, including Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and elemental analysis, etc., confirmed the successful prepared of this innovative stationary phase. The unique combination of amide, long alkyl chain, and imidazole ring in the hydrogel coating enables the stationary phase to function effectively in hydrophilic/reversed-phase/ion exchange liquid chromatography. Notably, the stationary phase exhibited superior separation performance owing to the synergistic effect of the ionic liquid and hydrogel. This was particularly evident when analyzing various analytes such as organic acids, nucleosides/bases, polycyclic aromatic hydrocarbons (PAHs) and anions. Furthermore, under our operating conditions, an excellent column efficiency of 53, 642.9 plates/m was achieved for theobromine. In summary, we have proposed a straightforward strategy to enhance the separation performance of hydrogel coatings in liquid chromatography, thereby broadening the potential applications of hydrogels in the field of separation.
Metal-organic frameworks (MOFs) with superior physicochemical properties have great potential for applications in chromatographic separation. However, currently popular methods for the synthesis of MOF-based silica composite materials usually require the use of harmful organic solvents and long-term high-temperature sealing reactions. In order to respond to the needs of green chromatography, it is urgent to develop a new green organic-solvent-free strategy for the synthesis of MOF@SiO2 composites. MIP-202 is a zirconium-MOF constructed from zirconium ion and l-aspartic acid, which features green synthesis as well as good hydrolytic stability and chemical stability. In this paper, SiO2-NH2 was first prepared in a hydrophilic deep eutectic solvent, and then an amino acid-based MOF material (MIP-202) was modified on the surface of the SiO2-NH2 in an aqueous solution to obtain a MIP-202@SiO2 composite material. The multi-mode separation performance of MIP-202@SiO2 as a promising liquid chromatographic stationary phase was particularly evaluated and the separation mechanisms were discussed. The MIP-202@SiO2 column exhibited excellent separation ability for aromatic positional isomers. In addition, chiral enantiomers and hydrophilic analytes were also satisfactorily detected and separated. This work provides a new approach for the facile synthesis of MOF-based liquid chromatographic separation material by using green deep eutectic solvent and water as the reaction media.
Recently circularly polarized luminescence (CPL) materials have attracted significant interest. Introducing reversible dynamic property to these materials has been a key focus in cutting-edge fields, such as in high-level information encryption. Here, we provided a novel and general strategy involving handedness-selective filtration and ground-state chiral self-recovery (CSR) in double film system to address this issue. Based on this strategy, we achieved CPL switch through the reversible modulation of ground-state chirality including absorption and scattering circular dichroism (CD) signals over the full UV-visible wavelength range (365-700 nm) in a single azobenzene polymer (PAzo) film. More importantly, by flexibly changing the type of fluorescent films, it is convenient to achieve general excited-state CSR, that is reversible switching of full-color including ideal white (CIE coordinate (0.33, 0.33)), as well as room-temperature phosphorescent CPL. All these CPL signals without almost any intensity decay after three cycles of on-and-off switching. Experimental results indicated that the trans-cis isomerization and ordered rearrangement of azobenzene units in PAzo film were the fundamental reasons for realizing CPL switching. Finally, based on this system we achieved dynamic visual encryption and decryption process including multiple decryption methods. This study provides an effective method for constructing a universally applicable chiroptical switch in excited state.
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