Oxidative coupling of methane (OCM) catalyzed by MnOx‐Na2WO4/SiO2 has great industrial promise to convert methane directly to C2–3 products, but its high light‐off temperature is the most challenging ...obstacle to commercialization and its working mechanism is still a mystery. We report the discovery of a low‐temperature active and selective MnOx‐Na2WO4/SiO2 catalyst enriched with Q2 units in the SiO2 carrier, being capable of converting 23 % CH4 with 72 % C2–3 selectivity at 660 °C. From experiments and theoretical calculations, a large number of Q2 units in the MnOx‐Na2WO4/SiO2 catalyst is a trigger for markedly lowering the light‐off temperature of the Mn3+↔Mn2+ redox cycle involved in the OCM reaction because of the easy formation of MnSiO3. Notably, the MnSiO3 formation proceeds merely through the SiO2‐involved reaction in the presence of Na2WO4: Mn7SiO12+6 SiO2↔7 MnSiO3+1.5 O2. The Na2WO4 not only drives the light‐off of this cycle but also gets it working with substantial selectivity toward C2–3 products. Our findings shine a light on the rational design of more advanced MnOx‐Na2WO4 based OCM catalysts through establishing new Mn3+↔Mn2+ redox cycles with lowered light‐off temperature.
For the oxidative coupling of methane (OCM) reaction, the MnOx‐Na2WO4/SiO2 catalyst enriched with Q2 units in the SiO2 carrier achieves 23 % CH4 conversion and 72 % C2–3 selectivity at 660 °C. A large number of Q2 units in MnOx‐Na2WO4/SiO2 is a trigger for markedly lowering the light‐off temperature of the Mn3+↔Mn2+ redox cycle because of the easy formation of MnSiO3.
In this study, a hydrostable Z‐scheme Ag/CsPbBr3/Bi2WO6 photocatalyst was designed and fabricated for the degradation of Rhodamine B (RhB). The structural instability of CsPbX3 perovskites in water ...is one of the main obstacles that restrict their practical application in photocatalytic wastewater treatment. The photocatalyst was prepared in three steps: passivation of CsPbBr3 nanocrystals (NCs) with 3‐mercaptopropionic acid (MPA), construction of a heterojunction between MPA‐passivated CsPbBr3 NCs and Bi2WO6 ultrathin nanosheets, and doping Ag nanoparticles as charge mediators in the heterojunction. The as‐obtained 5%Ag/20%CsPbBr3/Bi2WO6 exhibits good stability and excellent photocatalytic activity. The degradation rate is 93.9% in 120 min, which is 4.41 times than that of Bi2WO6.
Hydrostable Z‐scheme Ag/CsPbBr3/Bi2WO6 photocatalyst has been firstly fabricated which not only possesses remarkable long‐term stability in aqueous solution but also exhibits excellent photocatalytic activity for the degradation of organic dye under visible light irradiation.
An efficient NiSx‐modified β‐Ni(OH)2 electrode is reported for the selective oxidation reaction of 5‐hydroxymethylfurfural (HMFOR) with excellent electrocatalytic 5‐hydroxymethylfurfural (HMF) ...selectivity (99.4%), conversion (97.7%), and Faradaic efficiency (98.3%). The decoration of NiSx will evoke high‐valence Ni2+δ species in the reconstructed β‐Ni(OH)2 electrode, which are the real active species for HMFOR. The generated NiSx/Ni(OH)O modulates the proton‐coupled electron‐transfer (PCET) process of HMFOR, where the electrocatalytically generated Ni(OH)O can effectively trap the protons from the CHO end in HMF to realize electron transfer. The oxygen evolution reaction (OER) competes with the HMFOR when NiSx/Ni(OH)O continues to accumulate, to generate the NiSx/NiOx(OH)y intermediate. Density functional theory (DFT) calculations and experimental results verify that the adsorption energy of HMF can be optimized through the increased NiSx composition for more efficient capture of protons and electrons in the HMFOR.
NiSx‐modified β‐Ni(OH)2/Ni is elaborately designed for the efficient electrocatalytic oxidation of 5‐hydroxymethylfurfural (HMF) to valuable 2,5‐furandicarboxylic acid (FDCA), along with green hydrogen production. The reaction path and mechanism are comprehensively understood by ex/in situ characterization and theoretical calculations, and the high‐valence Ni2+δ is identified as the real active species.
High biomass crops have recently attracted significant attention as an alternative platform for the renewable production of high energy storage lipids such as triacylglycerol (TAG). While TAG ...typically accumulates in seeds as storage compounds fuelling subsequent germination, levels in vegetative tissues are generally low. Here, we report the accumulation of more than 15% TAG (17.7% total lipids) by dry weight in Nicotiana tabacum (tobacco) leaves by the co‐expression of three genes involved in different aspects of TAG production without severely impacting plant development. These yields far exceed the levels found in wild‐type leaf tissue as well as previously reported engineered TAG yields in vegetative tissues of Arabidopsis thaliana and N. tabacum. When translated to a high biomass crop, the current levels would translate to an oil yield per hectare that exceeds those of most cultivated oilseed crops. Confocal fluorescence microscopy and mass spectrometry imaging confirmed the accumulation of TAG within leaf mesophyll cells. In addition, we explored the applicability of several existing oil‐processing methods using fresh leaf tissue. Our results demonstrate the technical feasibility of a vegetative plant oil production platform and provide for a step change in the bioenergy landscape, opening new prospects for sustainable food, high energy forage, biofuel and biomaterial applications.
Display omitted
•Ultra-thin NiCo-MOF nanosheets with high mass loading (16.1 mg/cm2) were grown on NF.•Trimesic acid and terephthalic acid were used as mixed organic linkers.•Designed NiCo-MOF ...nanosheets yielded an areal capacitance of 5.84 F/cm2 at 1 mA/cm2.•Assembled NiCo-MOF//rGO ASC reached an energy density of 40 Wh/kg at 800 W/kg.•The assembled ASC retained 97.7% of the original capacitance after 10,000 cycles.
High mass loading metal–organic frameworks (MOFs) exhibit great potentials as electrode materials in energy storage, benefiting from their massive exposed reactive sites. Keeping high mass loadings while maintaining ultra-fine morphology of MOFs is very technically demanding. Herein, high mass loading binder-free NiCo-MOFs with mixed organic linkers (1,3,5-benzenetricarboxylate, BTC and p-benzenedicarboxylate, PTA) have been in-situ grown on Ni foam (NF) using Co(OH)2 as the template. The designed NiCo-(PTA)0.8(BTC)0.2 nanosheets achieved an areal capacitance of 5.84 F cm−2 (2.92 C cm−2) at a current density of 1 mA cm−2. The origin of the excellent electrochemical performances is carefully explained. The fabricated asymmetric supercapacitor (ASC) using NiCo-(PTA)0.8(BTC)0.2 nanosheets and reduced graphene oxide (rGO) as the positive and negative electrodes presented an excellent specific capacitance of 113 F g−1 at 1 A g−1. Besides, an outstanding energy density of 40 Wh kg−1 was achieved at the power density of 800 W kg−1. The assembled ASC device can retain as high as 97.7% of the original capacitance after 10,000 cycles, manifesting an excellent cycle stability. This work may provide a strategy for the preparation of high mass loading dual metal MOFs electrodes with ultra-fine morphology for high-performance supercapacitors.
Background and Purpose
Sunitinib is a small‐molecule TK inhibitor associated with hepatotoxicity. The mechanisms of its toxicity are still unclear.
Experimental Approach
In the present study, mice ...were treated with 60, 150, and 450 mg·kg−1 sunitinib to evaluate sunitinib hepatotoxicity. Sunitinib metabolites and endogenous metabolites in liver, serum, faeces, and urine were analysed using ultra‐performance LC electrospray ionization quadrupole time‐of‐flight MS‐based metabolomics.
Key Results
Four reactive metabolites and impaired clearance of sunitinib in liver played a dominant role in sunitinib‐induced hepatotoxicity. Using a non‐targeted metabolomics approach, various metabolic pathways, including mitochondrial fatty acid β‐oxidation (β‐FAO), bile acids, lipids, amino acids, nucleotides, and tricarboxylic acid cycle intermediates, were disrupted after sunitinib treatment.
Conclusions and Implications
These studies identified significant alterations in mitochondrial β‐FAO and bile acid homeostasis. Activation of PPARα and inhibition of xenobiotic metabolism may be of value in attenuating sunitinib hepatotoxicity.
The preparation strategies, structural characteristics, proton conductivity and applications of the N-heterocyclic MOFs in the light of the types of organic ligands are reviewed. Suggestions and ...trends for future research on such MOFs are elaborated and highlighted.
Display omitted
•Proton conductive N-heterocyclic metal–organic frameworks were reviewed.•MOFs are classified and described according to the type of ligands.•Proton conductivity and conducting mechanism were discussed.•The future development trend of such MOFs is prospected.
Recently, metal–organic frameworks (MOFs) have received widespread attention due to their roles as solid electrolytes in fuel cells. Herein, we will comprehensively summarize proton conductive MOFs constructed by N-heterocyclic organic ligands. The reason we are interested in these MOFs is that the main building blocks of such MOFs, N-heterocyclic organic ligands, can not only take part in coordination with the central metal ions to form stable structures, but also serve as a proton source, and can also build up complicated H-bonding systems with other components within the frameworks and adsorbed H2O units. These characteristics are very beneficial to them as promising proton conductors. Thus, we will summarize the preparation strategies, structural characteristics, proton conductivity and applications of the related MOFs in the light of the types of organic ligands (pure N-heterocyclic ligands; N-heterocyclic ligands bearing different substituted units covering carboxylate, hydroxy, phosphonate group, and sulfonic acid units, and so on). Finally, the challenges, opportunities and applications of such MOFs are elaborated and highlighted.
► Cellulose nanocrystals are produced by cation exchange resin as catalyst. ► The optimization process of cation exchange resin hydrolysis is investigated. ► Resin-catalyzed process is easy to handle ...and environmentally friendly.
Cellulose nanocrystals (CNC) were prepared from microcrystalline cellulose (MCC) by hydrolysis with cation exchange resin (NKC-9) or 64% sulfuric acid. The cation exchange resin hydrolysis parameters were optimized by using the Box–Behnken design and response surface methodology. An optimum yield (50.04%) was achieved at a ratio of resin to MCC (w/w) of 10, a temperature of 48°C and a reaction time of 189min. Electron microscopy (EM) showed that the diameter of CNCs was about 10–40nm, and the length was 100–400nm. Regular short rod-like CNCs were obtained by sulfuric acid hydrolysis, while long and thin crystals of cellulose were obtained with the cation exchange resin. X-ray diffraction (XRD) showed that, compared with MCC, the crystallinity of H2SO4-CNC and resin-CNC increased from 72.25% to 77.29% and 84.26%, respectively. The research shows that cation exchange resin-catalyzed hydrolysis of cellulose could be an excellent method for manufacturing of CNC in an environmental-friendly way.
In seed-bearing plants, the ovule ("small egg") is the organ within the gynoecium that develops into a seed after fertilization. The gynoecium located in the inner compartment of the flower turns ...into a fruit. The number of ovules in the ovary determines the upper limit or the potential of seed number per fruit in plants, greatly affecting the final seed yield. Ovule number is an important adaptive characteristic for plant evolution and an agronomic trait for crop improvement. Therefore, understanding the mechanism and pathways of ovule number regulation becomes a significant research aspect in plant science. This review summarizes the ovule number regulators and their regulatory mechanisms and pathways. Specially, an integrated molecular network for ovule number regulation is constructed, in which phytohormones played a central role, followed by transcription factors, enzymes, other protein and micro-RNA. Of them, AUX, BR and CK are positive regulator of ovule number, whereas GA acts negatively on it. Interestingly, many ovule number regulators have conserved functions across several plant taxa, which should be the targets of genetic improvement via breeding or gene editing. Many ovule number regulators identified to date are involved in the diverse biological process, such as ovule primordia formation, ovule initiation, patterning, and morphogenesis. The relations between ovule number and related characteristics/traits especially of gynoecium/fruit size, ovule fertility, and final seed number, as well as upcoming research questions, are also discussed. In summary, this review provides a general overview of the present finding in ovule number regulation, which represents a more comprehensive and in-depth cognition on it.
Purpose: To date, the prevalence and prognostic role of coronary artery calcification (CAC) in patients with chronic kidney disease (CKD) have been investigated in several studies, but have yielded ...conflicting results. The aim of this meta-analysis is to derive a more precise estimation of CAC prevalence in CKD patients and its association with cardiovascular events and mortality.
Methods: The relevant literature was identified and evaluated from inception until July 2018 through multiple search strategies on PubMed, Embase, and Web of Science. Cross-sectional or cohort (baseline data) studies reporting CAC prevalence were included. Data extracted from eligible studies were used to calculate effect estimates (ESs) and 95% confidence intervals (95%CI). We searched databases for observational studies that explored baseline CAC and subsequent cardiovascular or all-cause mortality risk in CKD patients.
Results: The meta-analysis included 47 studies; 38 of these were included in the final analysis of CAC prevalence. The pooled prevalence of CAC in random effect model was 60% (95%CI 53-68%). CAC was positively associated with an increased risk of all-cause mortality (hazard ratio HR 3.44; 95%CI 2.40-4.94), cardiovascular mortality (HR 3.87; 95%CI 2.06-7.26), and cardiovascular events (HR 2.09; 95%CI 1.19-3.67), when comparing individuals in the top CAC score group to those in the bottom CAC score group.
Conclusions: The pooled prevalence of CAC is highly prevalent. CAC is independently associated with all-cause and cardiovascular mortality risk as well as cardiovascular events among CKD patients. In view of the high heterogeneity, larger clinical trials are still needed.
PDF
