Co-exposure of heavy metals in rice and corn reveals a probabilistic health risk in Guizhou Province, China.

The adverse effects of heavy metals have arousing concern in the high geological background area, especially in southwestern Guizhou, China. However, the pollution status of heavy metals are still unclear when exposed to rice and corn in Guizhou province. Therefore, the concentration, pollution level, spatial distribution, and probabilistic health risks of Ni, Cr, Pb, Cu, and Zn are estimated in rice and corn. A total of 241 samples (117 for rice and 124 for corn) were collected from Guizhou province and measured by a method of inductively coupled plasma-mass spectrometry (ICP-MS). The results showed that rice and corn were contaminated with Ni and Cr. High concentrations of Ni were presented in the southeast of rice. It indicated that 22.0 % of rice samples were contaminated with Ni. HI values for children and adults exceeded 1.0 in rice and corn, suggesting that humans might be subject to probabilistic non-carcinogenic risks. FTCR demonstrated that rice and corn might cause probabilistic carcinogenic risks to children and adults, which were both greatly higher than 1.0 × 10-4. Moreover, the contributions of Ni to the HI and FTCR were the highest for adults and children. Therefore, more attention should be paid to the exposure of heavy metals in rice and corn, especially in Ni. The results would provide a novel prospective for pollution control and be helpful for environmental regulation.

Resistance exercise alleviates the prefrontal lobe injury and dysfunction by activating SESN2/AMPK/PGC-1α signaling pathway and inhibiting oxidative stress and inflammation in mice with myocardial infarction.

OBJECTIVES: Myocardial infarction (MI) induces inflammatory response and oxidative stress in the brain, which would be one of the causes of cardiac dysfunction. Exercise training is viewed as a feasible strategy to improve cardiac function of the infarcted heart. The aim of this study was to investigate whether exercise training could alleviate MI-induced prefrontal lobe injury via activating Sestrin2 (SESN2) signaling and inhibiting oxidative stress and inflammation. METHODS: Male C57BL/6 mice were divided into five groups: control group (CON), aerobic exercise group (AE), resistance exercise group (RE), whole-body vibration group (WBV) and electrical stimulation group (ES); and three groups: sham-operated group (S), sedentary MI group (MI) and MI with resistance exercise group (MRE). After four weeks of training, sensorimotor function, spatial learning, long-term and spatial memory, and cardiac function were detected. Then, mice were euthanized, and the prefrontal areas were separated for HE, Nissl, SESN2, microtubule-associated protein 2 (MAP2), neuron-specific nucleoprotein (NeuN), and TUNEL staining. Activation of SESN2/adenosine monophosphate-activated protein kinase (AMPK)/peroxisome proliferator activated receptor γ coactivator-1α (PGC-1α) signaling pathway and expression of proteins related to oxidative stress, inflammation and apoptosis in the prefrontal lobe were detected by western blotting. RESULTS: Different types of exercise training all activated the SESN2/AMPK/PGC-1α signaling pathway, and the effect of RE is the best. RE improved sensorimotor, learning, and memory impairments, increased the expressions of antioxidant, anti-inflammatory and anti-apoptotic proteins, reduced oxidative stress, inflammation and apoptosis, ultimately alleviated the prefrontal lobe injury and dysfunction in mice with MI. CONCLUSION: RE alleviates MI-indued prefrontal lobe injury and dysfunction by inhibiting the levels of oxidative stress, inflammation and apoptosis, partially via activating SESN2/AMPK/PGC-1α signaling pathway.

p-AKT/VPS4B regulates the small extracellular vesicle size in venous malformation endothelial cells.

OBJECTIVE: Small extracellular vesicle (sEV)-mediated intercellular communication is increasingly the key for the understanding of venous malformations (VMs). This study aims to clarify the detailed changes of sEVs in VMs. SUBJECTS AND METHODS: Fifteen VM patients without treatment history and twelve healthy donors were enrolled in the study. sEVs were isolated from both fresh lesions and cell supernatant, and were examined by western blotting, nanoparticle tracking analysis and transmission electron microscopy. Western blot analysis, immunohistochemistry and immunofluorescence were adopted to screening candidate regulator of sEV size. Specific inhibitors and siRNA were employed to validate the role of dysregulated p-AKT/vacuolar protein sorting-associated protein 4B (VPS4B) signaling on the size of sEVs in endothelial cells. RESULTS: The size of sEVs derived from both VM lesion tissues and cell model was significantly increased. VPS4B, whose expression level was mostly significantly downregulated in VM endothelial cells, was responsible for the size change of sEVs. Targeting abnormal AKT activation corrected the size change of sEVs by recovering the expression level of VPS4B. CONCLUSION: Downregulated VPS4B in endothelial cells, resulted from abnormally activated AKT signaling, contributed to the increased size of sEVs in VMs.

Real-Time Dissection of the Transportation and miRNA-Release Dynamics of Small Extracellular Vesicles.

Extracellular vesicles (EVs) are cell-derived membrane-enclosed structures that deliver biomolecules for intercellular communication. Developing visualization methods to elucidate the spatiotemporal dynamics of EVs' behaviors will facilitate their understanding and translation. With a quantum dot (QD) labeling strategy, a single particle tracking (SPT) platform is proposed here for dissecting the dynamic behaviors of EVs. The interplays between tumor cell-derived small EVs (T-sEVs) and endothelial cells (ECs) are specifically investigated based on this platform. It is revealed that, following a clathrin-mediated endocytosis by ECs, T-sEVs are transported to the perinuclear region in a typical three-stage pattern. Importantly, T-sEVs frequently interact with and finally enter lysosomes, followed by quick release of their carried miRNAs. This study, for the first time, reports the entire process and detailed dynamics of T-sEV transportation and cargo-release in ECs, leading to better understanding of their proangiogenic functions. Additionally, the QD-based SPT technique will help uncover more secrets of sEV-mediated cell-cell communication.

Soil exposure is the major fluoride exposure pathways for residents from the high-fluoride karst region in Southwest China.

In the karst areas of southwest China, soil fluoride levels are higher than in China (478 mg kg-1) and world (200 mg kg-1). High levels of F in the environment might pose a health risk to humans. The comprehensive exposure risk must be studied in this area. Herein, samples of crops and soil were collected from Bijie City, a typical karst area in southwest China, to investigate the pollution level and evaluate the comprehensive F exposure risk. The single-factor index (PFw) and the geological accumulation index (Igeo) were used. The hazard index (HI) was applied to assess exposure risk from multiple exposure routes. The results revealed that there is considerable F contamination in soil and crops in the study area. Average soil total fluorine (Ft) was 1139.13 mg kg-1, and soil water soluble F (Fw) was 3.792 mg kg-1. In corn, rice, wheat, and potatoes, F contents were 1.167-9.585, 1.222-6.698, 1.587-9.976, and 1.797-9.143 mg kg-1, respectively. The mean values of HI were 4.45 and 2.42 for children and adults, respectively, > 1, showing potential health risk exists. Youngsters are at a greater exposure risk than adults. From the results of contribution ratios of different exposure routes for health risk, the major exposure risk was determined to be from soil exposure. Based on this, we suggest that risk managers mainly strive to control the soil fluoride level and implement the risk education and communication.

Co-exposure of potentially toxic elements in wheat grains reveals a probabilistic health risk in Southwestern Guizhou, China.

Bijie is located at a typical karst landform of Southwestern Guizhou, which presented high geological background values of potentially toxic elements (PTEs). Recently, whether PTE of wheat in Bijie is harmful to human health has aroused people's concern. To this end, the objectives of this study are to determine the concentrations of PTE [chromium (Cr), nickel (Ni), arsenic (As), lead (Pb), cadmium (Cd), and fluorine (F)] in wheat grains, identify contaminant sources, and evaluate the probabilistic risks to human beings. A total of 149 wheat grain samples collected from Bijie in Guizhou were determined using the inductively coupled plasma mass spectrometer (ICP-MS) and fluoride-ion electrode methods. The mean concentrations of Cr, Ni, As, Cd, Pb, and F were 3.250, 0.684, 0.055, 0.149, 0.039, and 4.539 mg/kg, respectively. All investigated PTEs met the standard limits established by the Food and Agriculture Organization except for Cr. For the source identification, Cr and Pb should be originated from industry activities, while Ni, As, and Cd might come from mixed sources, and F was possibly put down to the high geological background value. The non-carcinogenic and carcinogenic health risks were evaluated by the probabilistic approach (Monte Carlo simulation). The mean hazard quotient (HQ) values in the three populations were lower than the safety limit (1.0) with the exception of As (children: 1.03E+00). However, the mean hazard index (HI) values were all higher than 1.0 and followed the order: children (2.57E+00) > adult females (1.29E+00) > adult males (1.12E+00). In addition, the mean carcinogenic risk (CR) values for Cr, As, Pb, and Cd in three populations were all higher than 1E-06, which cannot be negligible. The mean threshold CR (TCR) values were decreased in the order of children (1.32E-02) > adult females (6.61E-03) > adult males (5.81E-03), respectively, all at unacceptable risk levels. Moreover, sensitivity analysis identified concentration factor (C W ) as the most crucial parameter that affects human health. These findings highlight that co-exposure of PTE in wheat grains revealed a probabilistic human health risk. Corresponding measures should be undertaken for controlling pollution sources and reducing the risks for the local populace.

A histological study of vascular wall resident stem cells in venous malformations.

Vascular wall resident stem cells (VW-SCs) play a key role in vascular formation and remodeling under both physiological and pathological situations. They not only serve as a reservoir to supply all types of vascular cells needed, but also regulate vascular homeostasis by paracrine effects. Venous malformations (VMs) are common congenital vascular malformations which are just characterized by the deficient quantity and abnormal function of vascular cells. However, the existence and role of VW-SCs in VMs is still unclear at present. In this study, the level and distribution of VW-SCs in 22 specimens of VMs were measured by immunochemistry, double-labeling immunofluorescence, and qPCR, followed by the Spearman rank correlation test. We found that both the protein and mRNA expression levels of CD34, vWF, VEGFR2, CD44, CD90, and CD105 were significantly downregulated in VMs compared with that in normal venules. VW-SCs were sporadically distributed or even absent within and outside the endothelium of VMs. The expression of the VW-SC-related markers was positively correlated with the density of both endothelial cells and perivascular cells. All those results and established evidence indicated that VW-SCs were more sporadically distributed with fewer amounts in VMs, which possibly contributing to the deficiency of vascular cells in VMs.

Construction of a fast Li-ion path in a MOF-derived Fe3O4@NC sulfur host enables high-rate lithium-sulfur batteries.

Besides the adjustment of the active centres, the precisely designed microstructures of the carbon hosts also play a significant role in improving the battery performance. Herein, MOF-derived Fe3O4@NCs were prepared through a molten salt-assisted calcination method at different carbonization temperatures. Compared with the materials obtained at 700 °C, LK450 calcined at a lower temperature of 450 °C maintains suitable pore sizes and more N-doping and exhibits excellent Li-ion transport performance. Thus, the S/LK450 cathode can achieve an outstanding rate performance of up to 5 C (∼528 mA h g-1) and an extremely low capacity decay of 0.037% per cycle after 500 cycles at 1C. Notably, even with a high sulfur loading (4.0 mg cm-2), the S/LK450 cathode can still deliver a high capacity of 673 mA h g-1 at 0.2C after 100 cycles. Briefly, this work demonstrates the superiorities to prepare the samples at relatively low carbonization temperatures, which guarantee a better ion path structure and sufficient N-doping in the carbon skeleton.

Endothelial cells induce degradation of ECM through enhanced secretion of MMP14 carried on extracellular vesicles in venous malformation.

Venous malformations (VMs), featuring localized dilated veins, are the most common developmental vascular anomalies. Aberrantly organized perivascular extracellular matrix (ECM) is one of the prominent pathological hallmarks of VMs, accounting for vascular dysfunction. Although previous studies have revealed various proteins involved in ECM remodeling, the detailed pattern and molecular mechanisms underlying the endothelium-ECM interplay have not been fully elucidated. Our previous studies revealed drastically elevated extracellular vesicle (EV) secretion in VM lesions. Here, we identified increased EV-carried MMP14 in lesion fluids of VMs and culture medium of TIE2-L914F mutant endothelial cells (ECs), along with stronger ECM degradation. Knockdown of RAB27A, a required regulator for vesicle docking and fusion, led to decreased secretion of EV-carried MMP14 in vitro. Histochemical analysis further demonstrated a highly positive correlation between RAB27A in the endothelium and MMP14 in the perivascular environment. Therefore, our results proved that RAB27A-regulated secretion of EV-MMP14, as a new pattern of endothelium-ECM interplay, contributed to the development of VMs by promoting ECM degradation.

Multi-nanocavities and multi-defects synergetic enhancement for the electromagnetic absorption of the rGO-NG film.

Dielectric loss is an important way to eliminate electromagnetic pollution. In order to achieve high dielectric loss, a graphene film reduced graphene oxide-N doped graphene (rGO-NG) was constructed from graphene oxide-Ni@polydopamine (GO-Ni@PDA) via thein situsynthesis of hollow graphene spheres between graphene sheets. Thisin situwas achieved by means of electrostatic self-assembly and metal-catalyzed crystallization. Owing to the synergetic effect of multi-nanocavities and multi-defects, the prepared rGO-NG film shows an average shielding effectiveness (SE) of 50.0 dB in the range of 8.2-12.4 GHz with a thickness of 12.2µm, and the SE reflection is only 7.3 dB on average. It also exhibits an average dielectric loss tangent (tanδ) of 23.1, which is 26 and 105 times higher than those of rGO and rGO-Ni, respectively. This work provides a simple but effective route to develop high performance graphene-based materials for application as an electromagnetic interference shielding film in today's electronic devices.

Multisize CoS2 Particles Intercalated/Coated-Montmorillonite as Efficient Sulfur Host for High-Performance Lithium-Sulfur Batteries.

The chemisorption and catalysis of lithium polysulfides (LiPSs) are effective strategies to suppress the shuttle effect in lithium-sulfur (Li-S) batteries. Herein, multisize CoS2 particles intercalated/coated-montmorillonite (MMT) as an efficient sulfur host is synthesized. As expected, the obtained S/CoS2 @MMT cathode achieves an absorption-catalysis synergistic effect through the polar MMT aluminosilicate sheets and the well-dispersed nano-micron CoS2 particles. Furthermore, efficient interlamellar ion pathways and interconnected conductive network are constructed within the composite host due to the intercalation/coating of CoS2 in/on MMT. Therefore, the S/CoS2 @MMT cathode achieves an outstanding rate performance up to 5C (∼548 mAh g-1 ) and a high cycling stability with low capacity decay of 0.063 and 0.067 % per cycle for 500 cycles at 1C and 2C, respectively. With a higher sulfur loading of 4.0 mg cm-2 , the cathode still delivers satisfactory rate and cycling performance. It shows that the CoS2 @MMT host has great application prospects in Li-S batteries.

Building a Pyrazole-Benzothiadiazole-Pyrazole Photosensitizer into Metal-Organic Frameworks for Photocatalytic Aerobic Oxidation.

Charge separation plays a crucial role in regulating photochemical properties and therefore warrants consideration in designing photocatalysts. Metal-organic frameworks (MOFs) are emerging as promising candidates for heterogeneous photocatalysis due to their structural designability and tunability of photon absorption. Herein, we report the design of a pyrazole-benzothiadiazole-pyrazole organic molecule bearing a donor-acceptor-donor conjugated π-system for fast charge separation. Further attempts to integrate such a photosensitizer into MOFs afford a more effective heterogeneous photocatalyst (JNU-204). Under visible-light irradiation, three aerobic oxidation reactions involving different oxygenation pathways were achieved on JNU-204. Recycling experiments were conducted to demonstrate the stability and reusability of JNU-204 as a robust heterogeneous photocatalyst. Furthermore, we illustrate its applications in the facile synthesis of pyrrolo[2,1-a]isoquinoline-containing heterocycles, core skeletons of a family of marine natural products. JNU-204 is an exemplary MOF platform with good photon absorption, suitable band gap, fast charge separation, and extraordinary chemical stability for proceeding with aerobic oxidation reactions under visible-light irradiation.

Quaternary Ammonium-Mediated Delamination of Europium-Based Metal-Organic Framework into Ultrathin Nanosheets for the Selective Photoelectrochemical Sensing of Fe3.

Structural delamination of bulk layered metal-organic frameworks (MOFs) remains a great challenge, largely owing to a lack of general synthetic strategies. Here, we reported a simple solvent-free intercalation strategy for the delamination of rare-earth-based MOF (RE-MOF) with a topology structure of MIL-78 by tuning the chain length of quaternary ammonium salts. Four types of quaternary ammonium salts, involving tetraethylammonium bromide (TEAB), tetrapropylammonium bromide (TPAB), tetrabutylammonium bromide (TBAB), and hexadecyl trimethyl ammonium bromide (CTAB) were introduced to investigate their intercalation capabilities. It is evident in our case that the interruption/intercalation behavior of quaternary ammonium salts differs with their steric structures, and the chain-like CTAB can induce obvious delamination of MIL-78 crystals. Particularly, the CTAB-intercalated ultrathin Eu-based MIL-78 nanosheets exhibited unique selective photoelectrochemical sensing property toward trace amounts of Fe3+ ions in aqueous solution with a detection limit of 0.0899 µM at a signal-to-noise ratio of 3. These results demonstrated a green bottom-up strategy to obtain high-quality RE-MOF nanosheets for potential photocurrent response applications.

Five-second STEM dislocation tomography for 300 nm thick specimen assisted by deep-learning-based noise filtering.

Scanning transmission electron microscopy (STEM) is suitable for visualizing the inside of a relatively thick specimen than the conventional transmission electron microscopy, whose resolution is limited by the chromatic aberration of image forming lenses, and thus, the STEM mode has been employed frequently for computed electron tomography based three-dimensional (3D) structural characterization and combined with analytical methods such as annular dark field imaging or spectroscopies. However, the image quality of STEM is severely suffered by noise or artifacts especially when rapid imaging, in the order of millisecond per frame or faster, is pursued. Here we demonstrate a deep-learning-assisted rapid STEM tomography, which visualizes 3D dislocation arrangement only within five-second acquisition of all the tilt-series images even in a 300 nm thick steel specimen. The developed method offers a new platform for various in situ or operando 3D microanalyses in which dealing with relatively thick specimens or covering media like liquid cells are required.

In Situ Membrane Biotinylation Enables the Direct Labeling and Accurate Kinetic Analysis of Small Extracellular Vesicles in Circulation.

Circulating small extracellular vesicles (sEVs) are naturally occurring nanosized membrane vesicles that convey bioactive molecules between cells. Conventionally, to evaluate their behaviors in vivo, circulating sEVs have to be isolated from the bloodstream, then labeled with imaging materials in vitro, and finally injected back into the circulation of animals for subsequent detection. The tedious isolation-labeling-reinfusion procedures might have an undesirable influence on the natural properties of circulating sEVs, thereby changing their behaviors and the detected kinetics in vivo. Herein, we proposed an in situ biotinylation strategy to directly label circulating sEVs with intravenously injected DSPE-PEG-Biotin, aiming to evaluate the in vivo kinetics of circulating sEVs more biofriendly and accurately. Such an analysis strategy is free of isolation-labeling-reinfusion procedures and has no unfavorable influence on the natural behaviors of sEVs. The results showed that the lifetime of generic circulating sEVs in mice was around 3 days. Furthermore, we, for the first time, revealed the distinct in vivo kinetics of circulating sEV subpopulations with different cell sources, among which erythrocyte-derived sEVs showed the longest lifespan. Moreover, compared with circulating sEVs in situ or used as autograft, circulating sEVs used as allograft had the shortest lifetime. In addition, the in situ biotinylation strategy also provides a way for the enrichment of biotinylated circulating sEVs. In summary, this study provides a novel strategy for in situ labeling of circulating sEVs, which would facilitate the accurate characterization of their kinetics in vivo, thereby accelerating their future application as biomarkers and theranositic vectors.

Orthogonal-array dynamic molecular sieving of propylene/propane mixtures.

Rigid molecular sieving materials work well for small molecules with the complete exclusion of large ones1-3, and molecules with matching physiochemical properties may be separated using dynamic molecular sieving materials4-6. Metal-organic frameworks (MOFs)7-9 are known for their precise control of structures and functions on a molecular level10-15. However, the rational design of local flexibility in the MOF framework for dynamic molecular sieving remains difficult and challenging. Here we report a MOF material (JNU-3a) featuring one-dimension channels with embedded molecular pockets opening to propylene (C3H6) and propane (C3H8) at substantially different pressures. The dynamic nature of the pockets is revealed by single-crystal-to-single-crystal transformation upon exposure of JNU-3a to an atmosphere of C3H6 or C3H8. Breakthrough experiments demonstrate that JNU-3a can realize high-purity C3H6 (≥99.5%) in a single adsorption-desorption cycle from an equimolar C3H6/C3H8 mixture over a broad range of flow rates, with a maximum C3H6 productivity of 53.5 litres per kilogram. The underlying separation mechanism-orthogonal-array dynamic molecular sieving-enables both large separation capacity and fast adsorption-desorption kinetics. This work presents a next-generation sieving material design that has potential for applications in adsorptive separation.

Metal-organic frameworks as photoluminescent biosensing platforms: mechanisms and applications.

Biosensing is of vital importance for advancing public health through monitoring abnormalities in biological systems, which may be potentially associated with certain body dysfunctions. A wide range of luminescent materials have been actively pursued in the fabrication of biosensing platforms, particularly ones that can function in complex biological fluids with high selectivity and sensitivity. Recently, metal-organic frameworks (MOFs) have experienced rapid growth due to their tunable structures, large surface area, and being prone to surface engineering, etc. These virtues endow MOF materials with immense feasibility in the target-oriented construction of sensing platforms for specific applications. In this review, we extrapolated six sensing mechanisms for MOF-based photoluminescent biosensing platforms, including photoelectron transfer (PET), resonance energy transfer (RET), competition absorption (CA), structural transformation (ST), chemical conversion (CC), and quencher detachment (QD). Accordingly, recent progress of MOF-based materials in photoluminescence sensing of biomolecules, biomarkers, drugs, and toxins was highlighted. The objective of this review is to provide readers with an extensive overview of the design and synthesis of MOF materials for photoluminescence biosensing. The challenges and outlook are briefly discussed at the end.

Facile synthesis of copper selenides with different stoichiometric compositions and their thermoelectric performance at a low temperature range.

Copper selenide is widely considered to be a promising candidate for high-performance flexible thermoelectrics; however, most of the reported ZT values of copper selenides are unsatisfactory at a relatively low temperature range. Herein, we utilized some wet chemical methods to synthesize a series of copper selenides. XRD, SEM and TEM characterizations revealed that CuSe, Cu3Se2 and Cu2-x Se were prepared successfully and possessed different morphologies and sizes. Based on the analysis of their thermoelectric properties, Cu2-x Se exhibited the highest Seebeck coefficient and lowest thermal conductivity among the three samples owing to its unique crystal structure. After being sintered at 400 °C under N2 atmosphere, the electrical conductivity of Cu2-x Se enhanced considerable, resulting in a significant improvement of its ZT values from 0.096 to 0.458 at 30 to 150 °C. This result is remarkable for copper selenide-based thermoelectric materials at a relatively low temperature range, indicating its brilliant potential in the field of flexible thermoelectric devices.

 Neothelaxespileata, a new species from China (Hemiptera, Sternorrhyncha, Aphididae, Thelaxinae).

Neothelaxespileata Qiao sp. nov., found on Pileamartinii (Urticaceae) in China, is described and illustrated. Neothelaxes Chakrabarti & Quednau is also a new generic record for China.

Correction: Aggregation-induced phosphorescence sensitization in two heptanuclear and decanuclear gold-silver sandwich clusters.

[This corrects the article DOI: 10.1039/D0SC05095D.].