The development of rapid and field monitoring tools is highly desirable for the sensitive detection of organophosphate pesticide (OP) residues in water and agriculture products without interference. ...A novel disposable acetylcholinesterase (AChE) biosensor with low detecting potential (+50mV), good selectivity, and high sensitivity was developed based on electrochemically reduced graphene oxide and Nafion hybrid nanocomposite (Er-GRO–Nafion) modified electrode. The Er-GRO–Nafion nanocomposite with conductive and three-dimensional interpenetrating network owns excellent characters as electrode modification material. It effectively promoted the electron transfer rate of electrode interface, could catalyze the anodic oxidation of thiocholine at ultra-low potential, and facilitated the access of substrates to the active centers. The modified electrode was used for the electrochemical detection of dichlorvos after adsorbing AChE on the biocompatible matrix. By dexterously controlling the electrochemical reduction variables and optimizing the electrode preparation parameters, the proposed electrochemical biosensor showed high sensitivity, wide linear range (from 5.0 to 100ngmL−1 and from 1.0 to 20μgmL−1), low detection limit (2.0ngmL−1), good stability and reproducibility. It also had high precision for the real sample analysis, which indicated the good perspective for field application.
Summary
Heat stress transcription factors (HSFs) compose a large gene family, and different members play differential roles in regulating plant responses to abiotic stress. The objectives of this ...study were to identify and characterize an A2‐type HSF, FaHsfA2c, in a cool‐season perennial grass tall fescue (Festuca arundinacea Schreb.) for its association with heat tolerance and to determine the underlying physiological functions and regulatory mechanisms of FaHsfA2c imparting plant tolerance to heat stress. FaHsfA2c was localized in nucleus and exhibited a rapid transcriptional increase in leaves and roots during early phase of heat stress. Ectopic expression of FaHsfA2c improved basal and acquired thermotolerance in wild‐type Arabidopsis and also restored heat‐sensitive deficiency of hsfa2 mutant. Overexpression of FaHsfA2c in tall fescue enhanced plant tolerance to heat by triggering transcriptional regulation of heat‐protective gene expression, improving photosynthetic capacity and maintaining plant growth under heat stress. Our results indicated that FaHsfA2c acted as a positive regulator conferring thermotolerance improvement in Arabidopsis and tall fescue, and it could be potentially used as a candidate gene for genetic modification and molecular breeding to develop heat‐tolerant cool‐season grass species.
A series of LaNi1−xFexO3 (x = 0.0, 0.2, 0.4, 0.7, and 1.0) perovskites were synthesized and characterized by X-ray diffraction (XRD), N2 physisorption, scanning electron microscopy (SEM), ...H2-temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The perovskites were investigated for selective catalytic reduction of NOx by hydrogen (H2-SCR). It is shown that Fe addition into LaNiO3 leads to a promoted efficiency of NOx removal, as well as a high stability of perovskite structure. Moreover, easy reduction of Ni3+ to Ni2+ with the aid of appropriate Fe component mainly accounts for the enhanced activity. Meanwhile, deactivation of the sulfated catalysts is due to that sulfates mainly deposit on active Ni component while doping of Fe can protect Ni to some extent at the expense of partial sulfation.
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•A series of LaNi1−xFexO3 were prepared and investigated for H2-SCR.•Fe-doping leads to a better NOx removal and a high structural stability.•Easy reduction of Ni3+ to Ni2+ is crucial, and sulfates mainly deposit on Ni.•Fe addition can protect Ni to some extent at the expense of partial sulfation.
A ruthenium(II) bipyridyl derivative photoelectrochemical probe, Ru-1, is synthesized and coupled with TiO2 nanoparticles (Ru-1/TiO2) for the specific recognition and highly sensitive ...photoelectrochemical (PEC) detection of Hg2+ in a series of biofluids. The probe is designed with a chromophore, a thiocyanate recognition unit, a π-conjugated photoelectron-transfer pathway, and a phosphonate anchor. TiO2 nanoparticles with strong affinity to phosphonate and suitable conduction band energy are used as intermediate layers to increase the Ru-1 adsorption amount and amplify the photocurrent response. Under irradiation, the Ru-1/TiO2/fluorine-doped tin oxide (FTO), with strong visible light-harvesting capacity, aqueous stability, and efficient photoelectron transfer, shows a high and stable photocurrent response. In the presence of Hg2+, however, the specific Hg2+ and NCS coordination changes the photophysical properties of Ru-1, imposing the probe with a wider band gap, a weaker absorbance, and a poorer photoelectron and hole separation efficiency, thus resulting in a significant photocurrent decrease. On the basis of the Hg2+-induced photocurrent change, the Ru-1/TiO2/FTO shows good selectivity and high sensitivity toward the PEC detection of Hg2+, with wide linear ranges from 10–12 to 10–7 and 10–7 to 10–3 g/mL, and a low limit of detection of 0.63 pg/mL. The PEC probe is recyclable and accurate for selective detection of Hg2+ in urine, serum, and cell extracts. The whole analysis can be completed within 15 min. These good analytical performances indicate that the PEC method might have great potential for the onsite detection of small molecules in biosystems.
Background and Aims
The regulation of hepatic very‐low‐density lipoprotein (VLDL) secretion is vital for lipid metabolism whose pathogenetic status is involved in fatty liver disease and dyslipidemia ...seen in hepatic steatosis. Accumulated evidence suggest that apolipoprotein E (ApoE) is closely related to hepatic VLDL secretion. Here, we report that the expression of patatin‐like phospholipase domain containing protein 7 (PNPLA7) is strongly induced by hepatic steatosis and positively correlates with plasma triacylglycerol (TAG) levels in the human subjects, whereas the role of PNPLA7 in hepatic VLDL secretion is unknown.
Approach and Results
Herein, with genetic manipulation in the mice, the deficiency of hepatic PNPLA7 expression resulted in reduced VLDL secretion accompanied by enhanced hepatic lipid accumulation and decreased hepatic ApoE expression. Furthermore, knockdown of PNPLA7 in the livers of the db/db mice also resulted in significant reduction in plasma TAG level but aggravated hepatic steatosis. Importantly, we observed that PNPLA7 interacted with ApoE and presumably at the site of endoplasmic reticulum. Mechanistically, we have shown that PNPLA7 could modulate polyubiquitination and proteasomal‐mediated degradation of ApoE. Overexpressed ApoE restored the impaired VLDL‐TAG metabolism in PNPLA7‐knockdown primary hepatocytes.
Conclusion
PNPLA7 plays a critical role in regulating hepatic VLDL secretion by modulating ApoE stability through its interaction with ApoE.
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•A dynamic N- and H-involved cyclic reaction pathway proposed for NH3 production.•A dual-path mechanism including chemical looping and thermal catalysis illustrated.•Bottleneck of ...direct NN dissociation bypassed.
The synthesis of ammonia via the Haber-Bosch process using Fe-derived catalysts requires harsh reaction conditions. It is hence meaningful to develop catalysts for low-temperature synthesis of ammonia for industrial application. Herein for the first time, we report that with the synergy between LaN and Ru/ZrH2, NH3 can be synthesized via a dual-path mechanism. The LaN-promoted Ru/ZrH2 catalyst shows exceptionally high NH3 synthesis rate (up to 305 mmolNH3 gRu−1 h−1) at 350 °C under 1 MPa and remarkable durability (tested for 200 h). The outcomes of isothermal surface reaction and a suite of 15N2 and D2 isotopic labeling experiments reveal that the N3− of LaN reacts with H− ions to produce NH3, leaving behind N and H vacancies. The initial state of Ru/xLaN/ZrH2 can be restored by having the N and H entities replenished under the atmosphere adopted for NH3 synthesis. Moreover, based on the results of N2 reaction order, nitrogen K-edge NEXAFS, in situ XPS as well as in situ DRIFTS analyses under a 25%N2-75%D2 atmosphere, it is reckoned that the direct dissociation of N2 does not occur on the LaN-promoted Ru/ZrH2 catalyst while N2 hydrogenation takes place via an associative pathway under mild conditions. For the hydrogenation of N2, an appropriate amount of LaN would induce a synergic effect on the Ru active sites, leading to facile activation and hydrogenation of N2 to *N2H2. Nonetheless, an excess amount of LaN would result in blocking of Ru sites, consequently hindering the formation of *N2H2 and decreasing the catalytic activity. Following the associative and chemical looping pathways, the LaN-promoted Ru/ZrH2 catalyst bypasses the bottleneck of N2 direct dissociation, making the synthesis of NH3 at mild conditions possible.
Auxins and humic acid (HA) were investigated for their roles in adventitious root induction in azalea microshoots in our previous study. To reveal the regulatory mechanisms of auxins and HA in this ...process, measurements of the levels of reactive oxygen species (ROS), carbohydrates, and phenolic compounds and gene expression during in vitro root development were performed. During the adventitious root induction process, ROS levels in shoots treated with auxins and HA increased compared to untreated shoots, especially during the earliest period after transfer to the media. Media supplemented with NAA experienced increases in H 2 O 2 contents by 480%and 250%, respectively, after 7 and 14 days of culture. The phenolic compound levels were also enhanced in the shoots treated with auxins and HA, reflecting the different rooting-promoting abilities of both auxins and HA. The highest levels of total phenolic 68.6 mg·g −1 fresh weight (FW), polyphenolic acids (121.72 μg caffic acid/g FW), and total flavonols (162.42 μg quercetin/g FW) were recorded after 21 days for NAA media, but the maximum levels of anthocyanins (49.76 μg cyanindin/g FW) were recorded after 21 days for IBA medium. Soluble carbohydrate, starch, and soluble protein levels were increased in the shoots treated with all treatments; however, the influence of NAA treatments was stronger than that of other treatments for most investigated parameters. The NAA significantly enhanced soluble carbohydrates by 30%, 37%, and 25%, respectively, at 14, 21, and 28 days compared with untreated microshoots. Expression of the POD1 gene increased in the shoots submitted to HA treatment media. Expression levels of auxin response factors ( ARF s) increased with IBA- and NAA-treated explants, suggesting that ARF s may have diverse regulatory roles in adventitious root induction in evergreen azalea. Moreover, the profiles of the IAA1 , IAA9 , IAA14 , and IAA27 transcripts were analyzed to reveal their roles in the adventitious rooting of evergreen azalea microshoots. These results indicate that auxins and HA promote adventitious root induction in Rhododendron plants through their impact on ROS, carbohydrate contents, phenolic compound levels, and expression levels of different genes related to root development in evergreen azalea plants.
The insufficient availability and activity of interfacial water remain a major challenge for alkaline hydrogen evolution reaction (HER). Here, we propose an “on-site disruption and near-site ...compensation” strategy to reform the interfacial water hydrogen bonding network via deliberate cation penetration and catalyst support engineering. This concept is validated using tip-like bimetallic RuNi nanoalloys planted on super-hydrophilic and high-curvature carbon nanocages (RuNi/NC). Theoretical simulations suggest that tip-induced localized concentration of hydrated K+ facilitates optimization of interfacial water dynamics and intermediate adsorption. In situ synchrotron X-ray spectroscopy endorses an H* spillover-bridged Volmer‒Tafel mechanism synergistically relayed between Ru and Ni. Consequently, RuNi/NC exhibits low overpotential of 12 mV and high durability of 1600 h at 10 mA cm‒2 for alkaline HER, and demonstrates high performance in both water electrolysis and chlor-alkali electrolysis. This strategy offers a microscopic perspective on catalyst design for manipulation of the local interfacial water structure toward enhanced HER kinetics.A RuNi/NC catalyst with optimized interfacial water dynamics for alkaline H2 evolution is reported. The designed strategy shows enhanced catalytic activity by achieving 12 mV overpotential at 10 mA cm‒2 and 13.6-fold higher mass activity than Pt/C.
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