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Aims Whether changes in endothelial tight junctions (TJs) lead to the formation of thoracic aortic aneurysm and dissection (TAAD) and serve as an early indicator and therapeutic target remains elusive. Methods and results Single-cell RNA sequencing analysis showed aberrant endothelial TJ expressions in the thoracic aortas of patients with TAAD. In a β-aminopropionitrile (BAPN)-induced TAAD mouse model, endothelial TJ function was disrupted in the thoracic aortas at an early stage (5 and 10 days) as observed by a vascular permeability assay, while the intercellular distribution of crucial TJ components was significantly decreased by en face staining. For the non-invasive detection of endothelial TJ function, two dextrans of molecular weights 4 and 70 kDa were conjugated with the magnetic resonance imaging (MRI) contrast agent Gd-DOTA to synthesize FITC-dextran-DOTA-Gd and rhodamine B-dextran-DOTA-Gd. MRI images showed that both probes accumulated in the thoracic aortas of the BAPN-fed mice. Particularly, the mice with increased accumulated signals from 5 to 10 days developed TAAD at 14 days, whereas the mice with similar signals between the two time points did not. Furthermore, the protease-activated receptor 2 inhibitor AT-1001, which seals TJs, alleviated the BAPN-induced impairment of endothelial TJ function and expression and subsequently reduced TAAD incidence. Notably, endothelial-targeted ZO-1 conditional knockout increased TAAD incidence. Mechanistically, vascular inflammation and edema were observed in the thoracic aortas of the BAPN-fed mice, whereas these phenomena were attenuated by AT-1001. Conclusion The disruption of endothelial TJ function is an early event prior to TAAD formation, herein serving as a potential indicator and a promising target for TAAD.

Herein, we report a facile approach for the preparation of two-dimensional iodine nanosheets (2D iodine NSs) with good stability and high biocompatibility via an aqueous solvent-assisted ultrasonic route.

Low temperature and atmospheric pressure plasma-induced polymerization was demonstrated as a fast and facile strategy for tailoring of packing phase of COF-1 as well as preparing diverse covalent organic frameworks (COFs) including both two-dimensional (2D) COFs and three-dimensional (3D) COFs. By regulating the solvents, the fast construction of well-ordered AB staggered COF-1 and AA eclipsed COF-1 was facilely realized in minutes. The plasma approach presented here led to the rapid preparation of eight classical 2D COFs, including boronate ester-linkage (COF-5, COF-8 and COF-10), azine-linkage (NUS-2), β-ketoenamine-linkage (TpPa, TPBD), imine-linkage (ILCOF-1, Py-COF), and 3D-COF-102 (boroxine linkage) in less than 1 hour. Different from conventional methods, the proposed methodology required much less time, lower power, no extra heating, inert-gas protection and pressure. The fast nucleation and growth of COFs with good crystallinity, morphology and thermal stability can be achieved under mild conditions.

A simple, sensitive and cost-effective homogeneous catalysis photochemical vapor generation (PVG) system for HPLC separation and atomic fluorescence spectrometry detection was reported herein for the speciation analysis of trace Se(IV) and Se(VI). Homogeneous Cd ions as a catalyst were stable and reliable, without complex nanomaterial synthesis and coating. Under the conditions of 60 μg mL−1 Cd ions, 3.5 m reaction coil, 40% acetic acid and 0.30 mL min−1 of 5 mM Na2CO3–1.3 mM NaHCO3, the online HPLC-Cd-PVG-AFS system enabled us to achieve a calculated detection limit of 0.16 and 0.21 ng mL−1 for Se(IV) and Se(VI), respectively. Moreover, it could also work successfully even in a phosphate separation system. Under the optimized conditions of 60 μg mL−1 Cd ions, 5 m reaction coil, 40% acetic acid and 0.35 mL min−1 of 50 mM Na2HPO3, a detection limit of 0.49/0.78 ng mL−1 for Se(IV)/Se(VI) was achieved.

An ultraviolet light emitting diode (UV-LED) array chip as the irradiation source for nano-TiO2 catalyzed photochemical vapor generation (PCVG) was combined with a hollow electrode point discharge microplasma optical emission spectrometer (HEPD-OES) to realize instrumental miniaturization, and utilized for quantitative analysis of trace selenium (Se). Under the irradiation of the UV-LED array chip, Se(IV) and Se(VI) could be effectively converted into volatile species in a miniature quartz coil coating with nano-TiO2 on its inner wall as a photocatalyst. Meanwhile, volatile analyte species were totally guided into the hollow electrode and transported into the inside of micro-discharge plasma for excitation and enhanced sensitivity. Experimental conditions of PCVG and HEPD-OES were investigated in detail using an analytical line of Se at 203.98 nm through the peak area integrated for quantitation. Under optimized experimental conditions of 0.6 mL sample volume, 10% (v/v) acetic acid, 370 nm and 50 W LED, and 75 s UV irradiation, Se(IV) and Se(VI) could be detected with the same LODs, 3.9 μg L−1 and 4.1 μg L−1, respectively. The accuracy of the proposed method was validated by the analysis of the Certified Reference Materials (CRMs, GBW(E)080395 and BWB2427-2016) and real water samples. With the advantages of high compatibility, high efficiency, small size and low power consumption, the integration of UV-LED array chip based PCVG and HEPD-OES would be beneficial to fabricate miniaturized and portable devices for field analysis.

The metal ion-catalyzed (Ru+, Ir+) reactions of ethanol converting to butanol have been studied via ICP-MS/MS. The detection of organic small molecule intermediates (acetaldehyde and butyraldehyde) was achieved in both Ru+/C2H5OH and Ir+/C2H5OH systems. Several metal-adduct intermediates were observed in these reactions, improving the understanding of the reaction mechanism of ethanol transformation. The possible formation pathways of intermediates have been discussed.

Artesunate (AS), the first-line treatment of malaria with a satisfactory safety profile, has been repurposed as a potential anticancer candidate as it mainly generates reactive oxygen species (ROS) through its intrinsic endoperoxide bridge reacting with ferrous-based catalysts to suppress cancer cell growth. However, further clinical translation of AS is hindered by the attenuated anticancer efficacy due to insufficient ROS generation. Herein, we rationally integrated hydrophobic-modified AS (hAS) with biomimetic polydopamine (PDA) and biomineral calcium carbonate to fabricate high AS-loaded nanomedicine (Ca-PDA/hAS@PEG) for cancer chemo-photothermal therapy, which exerted anticancer effects in the following ways: (1) the heat was generated when PDA was irradiated by near-infrared (NIR) light for photothermal therapy. Meanwhile, the increased temperature accelerated the production of ROS from hAS, thus enhancing the anticancer efficacy of hAS-based chemotherapy; (2) hAS-mediated chemotherapy boosted the cancer inhibition effect of photothermal therapy by arousing the intracellular ROS levels in the presence of endogenous ferrous ions and sensitizing cancer cells to thermal ablation; (3) the integration of calcium carbonate into the nanoparticle facilitated the pH-responsive drug release for precise treatment. Such hybrid nanoparticles exhibited a combinational antitumor effect of photothermal therapy and chemotherapy in vivo with no systemic toxicity. Taken together, our work presents a facile strategy to improve the anticancer efficacy of AS by combining chemical modification and photothermal therapy-assisted endoperoxide bridge cleavage, which may offer opportunities to pave the way for clinical translation of AS-based nanomedicines. STATEMENT OF SIGNIFICANCE: The clinical translation of artesunate (AS) is hindered by the attenuated anticancer efficacy due to insufficient ROS generation. Herein, we rationally integrated hydrophobic-modified AS (hAS) with biomimetic polydopamine (PDA) and biomineral calcium carbonate to fabricate high AS-loaded nanomedicine (Ca-PDA/hAS@PEG) for improved cancer chemo-photothermal therapy. The heat generated from PDA in response to near-infrared light irradiation could locally ablate tumor as well as accelerate the production of ROS by hAS, thus enhancing the anticancer efficacy of hAS-based chemotherapy. On the other hand, hAS-based chemotherapy amplified the intracellular oxidative stress, sensitizing cancer cells to thermal ablation. Our work presents a facile strategy to improve the anticancer efficacy of AS by combining chemical modification and photothermal therapy-assisted endoperoxide bridge cleavage.

The tool box of site-specific cleavage for nucleic acid has been an increasingly attractive subject. Especially, the recent emergence of the orthogonally activatable DNA device is closely related to the site-specific scission. However, most of these cleavage strategies are based on exogenous assistance, such as laser irradiation. Endogenous strategies are highly desirable for the orthogonally regulatable DNA machine to explore the crucial intracellular biological process and cell signal network. Here, we found that the accurate site-specific cleavage reaction of phosphorothioate (PT) modified DNA by using myeloperoxidase (MPO). A scissors-like mechanism by which MPO breaks PT modification through chloride oxidation has been revealed. Furthermore, we have successfully applied the scissors to activate PT-modified hairpin-DNA machines to produce horseradish peroxidase (HRP)-mimicking DNAzyme or initiate hybridization chain reaction (HCR) amplification. Since MPO plays an important role in the pathway related to oxidative stress in cells, through the HCR amplification activated by this tool box, the oxidative stress in living cells has been robustly imaged. This work proposes an accurate and endogenous site-specific cleavage tool for the research of biostimuli and the construction of DNA molecular devices.

Chemical vapor generation (CVG) is widely used in analytical atomic spectrometry, with advantages of high efficiency of sample introduction (vapor generation and transportation) and matrix separation. Photochemical vapor generation (Photo-CVG) is a new subset of CVG and it has been demonstrated a powerful alternative to conventional CVG techniques due to its inherent advantages. For a long time, most research works have been devoted to improving vapor generation efficiency and expanding the vaporable element scope of Photo-CVG. Nowadays, with the help of nanomaterials and enhancement reagents, Photo-CVG covers a wide range of detectable elements and the vapor generation efficiency of some elements has been improved significantly. In this review, we summarizes the developments and applications of nanomaterials/enhancement reagents assisted Photo-CVG for analytical atomic spectrometry, including TiO2 and TiO2-based composites, MOFs and some metal ions utilized as photocatalysts, photo-oxidation/reduction and enhancement reagents; as well as nanomaterials for preconcentration/separation in Photo-CVG systems.

Chemical warfare agents (CWAs) are highly toxic compounds that have been used in wars or terrorist attacks. There is an urgent need to develop fast, inexpensive and sensitive on-site CWA inspection techniques. In this study, a low-temperature plasma (LTP) probe was directly coupled with a metal needle tip where sample molecules were desorbed and ionized in the ambient environment for subsequent analysis using mass spectrometry (MS). We found that metal needles greatly increased the ionization efficiencies compared with non-conductive sample substrates. Based on this finding, a method for rapid and highly sensitive detection and quantification of CWA-related compounds, including dimethyl methylphosphonate (DMMP), isopropyl methylphosphonic acid (IMPA), methylphosphonic acid (MPA) and thiodiglycol (TDG) was established. The whole workflow was completed in 10 s with a dynamic range of 1–500 μg L−1, and the limit of detection (LOD) was 500–980 ng L−1. Analytes were spiked in real-world water samples and quantified using this approach with satisfactory recoveries. Our results indicated that metal needle-enhanced LTP-MS will be a useful technique for the highly sensitive detection of CWAs.

A fast (down to 1 min), power-saving (watt) and green strategy was proposed for preparing diverse and fine-tuned metal–organic frameworks (MOFs) and MOFs-based composites in either DMF or ethanol, catalyzed by liquid-phase plasma generated via dielectric barrier discharge (DBD).

A low-temperature plasma-based post-synthetic modification method was developed to directly introduce the hydroxy group into UiO-66 metal–organic frameworks (MOFs). UiO-66 can be endowed with greatly enhanced fluorescence properties after plasma treatment, with which a reliable sensing platform for arsenic has been established.

A simple multiplexed digital microRNA detection strategy with fluorescence flow cytometry was proposed. By isothermal ligation-rolling circle amplification, multiplexed microRNAs could be simultaneously converted to a series of nanoflower balls (NFBs) and counted by flow cytometry directly.

A miniaturized UV-LED photochemical reactor is proposed for selenium photochemical vapor generation (Photo-CVG). The miniaturized Photo-CVG reactor with a coin size mainly consists of an ultraviolet light-emitting-diode (UV-LED) and a quartz coil with nano-TiO2 coating on its inner wall. It was coupled with an atomic fluorescence spectrometer (AFS) as a sample introduction device for trace selenium determination. The nano-TiO2 coating process, UV-LED wavelength and correlative experimental parameters as well as potential interference were investigated in detail. Under optimized experimental conditions, limits of detection of 0.21 and 0.28 μg L−1 for Se(VI) and Se(IV) were obtained, respectively, with a relative standard deviation (n = 3) of 2.5% and 1.0% at 20 μg L−1. The potential application of this UV-LED Photo-CVG AFS was demonstrated by successfully analyzing a certified reference water sample and several mineral water samples.

MIL-100(Fe) was the first time used in a continuous flow system. Under the continuous flow, higher catalytic efficiency was achieved than in the batch system, which is attributable to a lower inhibition by products. This method provides a new approach to MOFs applied as heterogeneous catalysts for the synthesis of fine chemicals.

Nano g-C 3 N 4 /TiO 2 composite was synthetized and utilized as a novel photocatalyst for enhanced photochemical vapor generation for sample introduction to atomic fluorescence spectrometry. High reduction efficiency for Se (VI) was obtained to facilitate its ultrasensitive determination by atomic fluorescence spectrometry, with a limit of detection of 0.08 ng mL − 1 . The photocatalytic mechanism of this composite was also discussed and demonstrated its highly efficient photocatalytic capacity and promissing applications in trace selenium (VI) determination and extraction.

A triazine-based covalent organic framework, CTF-1, for the first time, was found to possess both intrinsic peroxidase-like activity and oxidase-like activity and be capable to catalyze the oxidation of chromogenic substrates with or without H2O2 with high efficiency as a robust catalyst. Related oxidization mechanism was thoroughly studied, and the according catalytic properties of CTF-1 was also evaluated. What's more, a facile and effective colorimetric assay was established to detect biothiols without using any oxidizing agents. Compared to natural enzymes and other reported artificial enzymes, CTF-1 has also demonstrated the advantages including low cost, easy preparation, good stability, and high catalytic activity, which made it a very promising enzyme-mimetic alternative in potential applications in biosensors for the future.

In this work, metal organic framework (MOF) UiO-66 with strong stability in water was synthesized and used for the preconcentration of ultratrace arsenic in environment water and the precipitated UiO-66 was converted to slurry for direct determination with hydride generation-atomic fluorescence spectrometry (HG-AFS). Factors affecting the adsorption of arsenic by UiO-66, including pH, adsorption time, stability of UiO-66, masking agents together with the optimum conditions of HG-AFS were investigated in detail. The performance of UiO-66 for adsorbing arsenic was excellent at room temperature over a wide range of pH from 1 to 11, and adsorption efficiencies of > 95% could be achieved within only 5 min. Meanwhile, since conventional digestion process is avoided, the slurry sampling method is fast and convenient with greatly reduced matrix interference. Under the optimum conditions, it shows a good linear relationship between AFS intensities (I) and the concentrations of arsenic (C) (I = 547C + 61) with linear correlation coefficients better than 0.99. A precision of 3% (RSD%, n = 11) at 1 ng/mL and a limit of detection (LOD) of 0.0002 ng/mL were obtained.

The toxicity of elements largely depends on their chemical forms. Therefore, the elemental speciation analysis is of great importance and a hot topic in environmental science and engineering, food science, and biology. The use of nanomaterials in spectrometric detection provides a convenient, versatile, and sensitive technique for elemental speciation analysis. In this concise review, we aim to provide a brief overview of the versatility of nanomaterials in spectrometric elemental speciation analysis with focus on four elements: mercury, arsenic, chromium, and selenium. Various types of nanomaterials, together with their roles in the speciation analysis developed with prevailing spectrometric techniques, are discussed. We also offer an insight into the research trend of the application of nanomaterials for chemical speciation analysis.

Metal organic framework MIL-125-NH2 was used as a photocatalyst for the photochemical vapor generation to establish an efficient and accurate method for highly sensitive determination of trace selenium by inductively coupled plasma optical emission spectrometry. The mixture of Se (IV) and Se (VI), MIL-125-NH2 nanoparticles and a low molecular weight organic acid was mixed to generate gaseous selenium-containing species which was separated from its liquid phase and transported to inductively coupled plasma optical emission spectrometer for determination. Influencing factors including carrier gas flow rate, type and concentration of catalyst, type and concentration of organic acid, UV irradiation time and power, and sample pH were carefully studied. Under the optimized conditions, a catalytic efficiency of more than 80% was achieved. The limits of detection for Se (IV) and Se (VI) were found to be the same and as low as 0.3 ng/mL. The relative standard deviation of Se (IV) and Se (VI) was 2.7% and 2.1% at 20 ng/mL (n = 11), respectively. The accuracy of the method was evaluated by analysis of natural mineral water and certified reference materials.

UiO-66 metal-organic frameworks (MOFs) can be endowed with greatly enhanced photocatalytic properties by introducing titanium into the frameworks. A microwave-assisted method was developed to substitute the zirconium with titanium in UiO-66, which was accomplished within a few hours compared to several days reported previously, with the crystallinity well maintained and photocatalytic activities tremendously improved.

In this work, Au nanoparticles self-assembled with covalent-organic frameworks via a 1 min process at room temperature, and the obtained nanocomposite was employed as a new type of surface-enhanced Raman scattering sensor for the recognition of polycyclic aromatic hydrocarbons with high sensitivity.

A fast (down to 1 min), power-saving (watt) and green strategy was proposed for preparing diverse and fine-tuned metal-organic frameworks (MOFs) and MOFs-based composites in either DMF or ethanol, catalyzed by liquid-phase plasma generated via dielectric barrier discharge (DBD).

Multiplex biomolecular analysis with inductively coupled plasma mass spectrometry (ICP-MS) becomes increasingly important in clinical diagnosis and single cell analysis. However, the sensitivity of ICP-MS-based immunoassay is only comparable or lower than those of fluorescence methods at the present stage. Therefore, designing elemental tags with a large number of metal atoms is necessary to achieve high-sensitive detection. In this work, we proposed a new strategy to build up elemental tag loading with hundreds of rare earth ions by coupling alkyne-DNA chains with rare earth element (REE)-DOTA complexes a click chemistry reaction. There are about 2 orders of magnitude improvement in sensitivity compared with single metal-ion tags. DNA chains with multialkynyl groups were facilely prepared by PCR synthesis. Moreover, the DNA-based elemental tags own excellent water-solubility and biocompatibility. The tags would be potentially applied to mass cytometry and clinical diagnosis.

Intermediates in the gas-phase reaction of diatomic [TaO]+ with CH4 to generate ethane and ethylene have been explored using ICP-MS/MS complemented by high-level quantum chemical calculations. [TaOH]+, [TaOCH2]+, [TaOC2H6]+and [TaOC2H4]+ were identified and the formation pathways of them were discussed, revealing the mechanistic scenario for this oxidative coupling of methane to the C2 hydrocarbons process.

A facile colorimetric sensing method for biothiols was developed, based on photocatalytic property of metal-organic frameworks (MOFs), UiO-66(NH 2 ) nanoparticles (NPs), as peroxidase mimics under light irradiation. By the irradiation of a light emitting diode (LED) source, the colorless chromogenic substrate, 3,3′,5,5′-tetramethylbenzydine (TMB), was oxidized into blue oxTMB with the aid of the catalytic UiO-66(NH 2 ) NPs. With the existence of biothiols, the oxidization was prohibited, with the blue color paled and absorbance intensity decreased with the concentration of biothiols in a linear manner. Real samples of cysteine, glutathione, and homocysteine were analyzed under the optimized conditions, with high sensitivity (the limit of detection was calculated as 306 nM, 310 nM, and 330 nm respectively) and selectivity. The recovery ranged from 93% to 107% with good precisions (RSD%≤5%). This photocatalytic property of UiO-66(NH 2 ) as peroxidase mimics was studied based on steady-state kinetics, and the mechanism of oxidization process was also briefly discussed. This developed MOFs-based colorimetric sensing method demonstrated advantages over others for biothiols sensing, including high photo-catalytic activity compared to other nanomaterials, oxidation without H 2 O 2 , ease of regulation with the LED source, and low cost without expensive instrument and technically demanding.

In situ gel delivery systems are preferred over conventional systems due to sustained and prolonged release action of therapeutic payload onto the targeted site. Thermogel, a form of in situ gel-forming polymeric formulation, undergoes sol-gel transition after administration into the body. At room temperature, the system is an aqueous polymer solution that easily entraps therapeutic payload by mixing. Upon injection, the higher physiological temperature causes gelation in situ because of the presence of thermosensitive polymers. The gel degrades gradually over time, allowing sustained release of therapeutics localized to the site of interest. This minimizes systemic toxicity and improved efficacy of drug release to the targeted site. Thermogel properties can be easily altered for specific applications via substitution and modification of components in diblock and triblock copolymer systems. The feasibility of fine-tuning allows modifications to biodegradability, biocompatibility, biological functionalization, mechanical properties, and drug release profile. This review summarized recent development in thermogel research with a focus on synthesis and self-assembly mechanisms, gel biodegradability, and applications for drug delivery, cell encapsulation and tissue engineering. This review also assessed inadequacy of material properties as a stand-alone factor on therapeutic action efficacy in human trials, with a focus on OncoGel, an experimental thermogel that demonstrated excellent individual or synergistic drug delivery system in preclinical trials but lacked therapeutic impact in human trials. Detailed analysis from all aspects must be considered during technology development for a successful thermogel platform in drug delivery and tissue engineering.

In this work, magnetic Fe3O4@ZIF-8 core-shell nanoparticles (MNPs) were employed for effective adsorption of inorganic arsenic for preconcentration, with adsorption mechanism thoroughly discussed. The adsorbed inorganic arsenic was easily separated by a magnet along with the MNPs from the sample matrix, with possible matrix interference eliminated. The MNPs were then completely dissolved in hydrochloric acid prior to the determination of inorganic arsenic by hydride generation-atomic fluorescence spectrometry. The Fe3O4@ZIF-8 MNPs were prepared with a facile step-by-step assembly method in aqueous solution at room temperature. Under the optimized conditions, the sensitivity for inorganic arsenic determination was significantly increased through preconcentration, with satisfactory analytical merits obtained.

It was found that a capillary electrophoresis (CE) process can be induced by starting a low-temperature d.c. liquid-electrode glow discharge (GD). A novel capillary microplasma analytical system (C-μPAS) was constructed by interface-free coupling of d.c. glow discharge optical emission spectrometry (GD-OES) to CE and was applied in elemental (speciation) analysis. A GD was generated at one end of a capillary, and initiated not only a capillary electrophoresis process but also a microplasma; a sample was injected at the other end of the capillary, separated by CE, and detected by GD-OES. This portable C-μPAS integrates introduction of the sample, separation of the analyte species, and detection of the analytical signal into one unit. The performance of this new analytical system was first evaluated by the analysis of a mixed aqueous solution of mercury, cadmium, chromium, sodium and organic or inorganic species without derivatization, and the absolute limits of detection (LODs) were found to be in the range of 0.5 to 500 picograms under the optimized experimental conditions. Preliminary experimental results for mercury speciation showed that it provided effective separation and results as accurate as those obtained by HPLC-ICP-MS. The working mechanism of this system is discussed, with the theoretically calculated electron temperature and electron density of the microplasma. This C-μPAS has the advantages of portable instrumentation, green chemistry (low power consumption, tiny sampling volume and almost no pollutants), high sensitivity (detection of optical emissions), low interference (separation by CE and spectral resolution), versatility (organic, inorganic, cationic or anionic analytes), and fast analysis (several minutes). It should have a very promising future in a range of areas such as environmental analysis, metallomics research, water analysis, online monitoring and field analytical chemistry.

Rhodamine B hydrazide (RBH) was prepared as a new derivatizing reagent for residual formaldehyde in a drug such as N-butyl-2-cyanoacrylate (NBCA). RBH reacted with formaldehyde rapidly at room temperature, and the resulting derivative can be detected sensitively at 238 nm. After optimizing the derivatization and chromatographic separation conditions, RBH as a pre-column derivatizing reagent has been successfully used for the analysis of formaldehyde in real NBCA samples by high-performance liquid chromatography (HPLC). The detection limit of the method is 0.004 μg/mL for formaldehyde, and the recovery is 94.0%-96.6%. Most notably, compared with the previous HPLC methods, the developed method has the advantages of mild derivatization temperature, short derivatization time and high sensitivity.

Ethanol to butanol (ETB) process is an attractive route to upgrade abundant substrate into a product with superior properties in energy industry. For the mechanism research, the detection of intermediates is vital. In this paper, intermediates in ETB reaction catalyzed by monoxide ions [ZrO]+/[CeO]+/[TiO]+ were investigated by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). Some important organic small molecule intermediates, metal-adduct intermediates and their formation pathways were discussed to reveal the reaction mechanism in this research. Isotopic labelling experiments were also designed to ensure the existence of these intermediates.

Cadmium ion-enhanced photochemical vapour generation directly from Se(vi) has for the first time been reported here, and the key mechanism of the in situ formation of nano-CdSe as a photocatalyst has been revealed.

As incipient fault of rotating machinery is weak and interfered by noise, it is difficult for characteristic information determination and incipient classification. In this research, a new method is put forward on rolling element bearing (REB) incipient impact information using synchronous averaging reassigned wavelet scalogram (SARWS) according to time–frequency analysis. Firstly, multi-cycle signal is processed by continuous wavelet transform. Then, time frequency distribution for every working cycle of vibration signal is obtained by wavelet scalogram (WS) based on time domain information. Thirdly, reassigned wavelet scalogram (RWS) for every working cycle of REB can be calculated. In the end, synchronous averaging is applied on RWS, which can effectively reduce noise interference and identify the weak fault information. Both simulated signals and real vibration signals collected from REB of rotating machinery are used to verify this proposed method. Analyzed results show that the proposed method is effective for REB incipient weak fault classification.

Gold nanoparticles (AuNPs)-based colorimetric assays are of particular interest since molecular events can be easily read out with the color changes of AuNPs by the naked eye. However, the molecular recognitions occur almost exclusively in the liquid phase (i.e., the interaction between target analytes and AuNPs is always proceeded in the presence of the sample matrix). Since the aggregation of the unmodified AuNPs is prone to be influenced by the ionic strength of the solution, sample matrix will cause undesirable interference. Here, we proposed a new type of AuNP-based colorimetric assay, in which target analyte selenium was first converted to its hydride chemical vapor (H2Se) and then delivered into the solution of AuNPs to induce color change. Therefore, sample matrix (for example, high salinity) were eliminated, leading to excellent selectivity. With the aid of hydride generation, the proposed method offered a detection limit of 0.05 μM with UV–vis detection and 1 μM with the naked eye. Successful ap...