Promotion effect of Ni doping on the oxygen resistance property of Fe/CeO2 catalyst for CO-SCR reaction: Activity test and mechanism investigation.

Catalytic reduction of NO using CO, which is usually present in the flue gas of the iron and steel industry, is considered as an economical and eco-friendly de-NOx method (CO-SCR). However, the oxygen present in the flue gas will significantly inhibit the CO-SCR activity of the catalyst, thereby limiting its industrial application. Herein, catalysts based on iron and cerium oxides were prepared and modified with different metals to investigate their performance for the CO-SCR reaction in the presence of oxygen. The results show that the Fe/CeO2 catalyst can reach 99% NO conversion at 200 °C, but its activity decreased dramatically to 42.7% when the oxygen is present (0.5 vol%). By contrast, the NO conversion of Ni-doped Fe/CeO2 catalyst demonstrated significant enhanced oxygen resistance and could achieve 92% even at 150 °C in the presence of 0.5 vol% oxygen. Characterization techniques such as N2 adsorption, XRD, SEM/TEM, XPS, H2-TPR, and in situ DRIFT were employed to investigate the mechanism of the improved oxygen resistance property of Ni-doped catalyst. The results show that the doped Ni can interact with Fe species, increases the BET surface area of the catalyst and generates more surface oxygen vacancies (SOV) and surface synergetic oxygen vacancy (SSOV) in CO-SCR reaction, thereby improving the redox performance of the catalyst. In situ DRIFT results show that the better redox performance of NiFe/CeO2 catalyst is conducive to the conversion of adsorbed NOx species to the reactive intermediate NO2- species during the reaction. Meanwhile, the enhanced SOV/SSOV in the NiFe/CeO2 catalyst can remain active in the presence of oxygen. Therefore, the NiFe/CeO2 catalyst exhibits a promising catalytic activity in CO-SCR reaction when oxygen is present.

LCZ696 and preservation of renal function in heart failure: A meta-analysis of 6 randomized trials.

Patients with heart failure (HF) are prone to combine with renal insufficiency. Recently, LCZ696 has been used in the treatment of HF, but whether LCZ696 is better than angiotensin converting enzyme inhibitors/angiotensin receptor antagonists (ACEI/ARB) in renal protection for HF patients has not been investigated. Therefore, we conducted a meta-analysis focusing on LCZ696 and its role in preservation of renal function in HF patients. Embase, PubMed, the Cochrane Library and ClinicalTrials.gov databases were electronically searched for available randomized controlled trials (RCTs). HF patients taking LCZ696 or ACEI/ARB were assessed for renal adverse events. The last search date was Sep 20, 2019. A total of 14959 patients from 6 trials were included in this meta-analysis. As compared to ACEI/ARB, LCZ696 significantly reduced the risk of renal function deterioration (odds ratio 0.77, 95% confidence interval 0.61-0.97, P = 0.02). In summary, LCZ696 may have superior renal protection in HF patients compared with ACEI/ARB.

A turn-on fluorescent probe for vitamin C based on the use of a silicon/CoOOH nanoparticle system.

The authors describe a fluorometric method for the turn-on determination of vitamin C (ascorbic acid). The blue fluorescence of silicon nanoparticles (SiNPs; with excitation/emission maxima at 350/450 nm) is found to be quenched by CoOOH nanoparticles (NPs). In the presence of vitamin C, the CoOOH NPs are decomposed by a redox reaction between the diol group of vitamin C and CoOOH NPs. As a result, fluorescence recovers. On the basis of this finding, a fluorometric method was designed for the turn-on detection of vitamin C. Under optimal conditions, the method has a low detection limit (0.47 µM) and a linear response in the 0.5 µM to 20 µM a concentration range. It was successfully applied to the determination of vitamin C in spiked red grape and orange juice, and in vitamin C tablets. Graphical abstract A target-triggered dissociation of quencher-based strategy for the fluorescence "turn-on" detection of vitamin C was developed. It is based on surface energy transfer (SET) and an inner filter effect (IFE) between silicon nanoparticles and CoOOH nanoparticles as well as the redox reaction between vitamin C and CoOOH nanoparticles.

Synergistic electron transfer effect-based signal amplification strategy for the ultrasensitive detection of dopamine.

The selective and sensitive detection of dopamine (DA) is of great significance for the identification of schizophrenia, Huntington's disease, and Parkinson's disease from the perspective of molecular diagnostics. So far, most of DA fluorescence sensors are based on the electron transfer from the fluorescence nanomaterials to DA-quinone. However, the limited electron transfer ability of the DA-quinone affects the level of detection sensitivity of these sensors. In this work, based on the DA can reduce Ag+ into AgNPs followed by oxidized to DA-quinone, we developed a novel silicon nanoparticles-based electron transfer fluorescent sensor for the detection of DA. As electron transfer acceptor, the AgNPs and DA-quinone can quench the fluorescence of silicon nanoparticles effectively through the synergistic electron transfer effect. Compared with traditional fluorescence DA sensors, the proposed synergistic electron transfer-based sensor improves the detection sensitivity to a great extent (at least 10-fold improvement). The proposed sensor shows a low detection limit of DA, which is as low as 0.1 nM under the optimal conditions. This sensor has potential applicability for the detection of DA in practical sample. This work has been demonstrated to contribute to a substantial improvement in the sensitivity of the sensors. It also gives new insight into design electron transfer-based sensors.

Highly sensitive and selective determination of copper(II) based on a dual catalytic effect and by using silicon nanoparticles as a fluorescent probe.

The authors describe a silicon nanoparticle-based fluorometric method for sensitive and selective detection of Cu2+. It is based on the catalytic action of Cu2+ on the oxidation of cysteine (Cys) by oxygen to form cystine and the by-product H2O2. The generated H2O2 is catalytically decomposed by Cu2+ to generate hydroxyl radicals which oxidize and destroy the surface of SiNPs. As a result, the blue fluorescence of the SiNPs is quenched. The method has excellent selectivity due to the dual catalytic effects of Cu2+, which is much better than most previously reported nanomaterial-based assays for Cu2+. Under the optimal conditions, the method has low detection limit (29 nM) and a linear response in a concentration range from 0.05 µM to 15 µM. The method has been successfully applied to the determination of Cu2+ in spiked real water samples, and the results agreed well with those obtained by the Chinese National Standard method (GB/T 7475-1987; AAS). Graphical abstract Schematic presentation of a fluorometric method for the determination of Cu2+ based on the dual catalytic effects of Cu2+, and the oxidative effect of hydroxy radicals on the surface of silicon nanoparticles (SiNPs). The method has a 29 nM detection limit and good selectivity.