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•Titanate nanotubes (TNTS) were employed as a catalyst support of CoFe2O4.•TNTs could promise small size and good dispersion of CoFe2O4 nanoparticles.•CoFe2O4/TNTs hybrid exhibited ...better catalytic efficiency than sole CoFe2O4.•The hybrid also showed enhanced mineralization ability and less Co2+ leaching.
Magnetic spinel ferrites, as heterogeneous catalysts to generate powerful radicals from peroxymonosulfate (PMS) for the degradation of organic pollutants, have received much attention in recent years due to the characteristic of environmental benefits. In this study, with titanate nanotubes (TNTs) as catalyst support, a novel CoFe2O4/TNTs hybrid was constructed by an impregnation-calcination method. Characterization results revealed that TNTs support could promise small size and good dispersion of CoFe2O4 nanoparticles. Compared to the pure CoFe2O4, the as-prepared CoFe2O4/TNTs not only exhibited better performance in catalytic decomposition of Rhodamine B, but also realized higher total organic carbon removal and less cobalt leaching, which could be attributed to the enhanced catalytic ability from smaller CoFe2O4 nanoparticles and the unique ion-exchange ability from TNTs support. Some influential factors, including reaction temperature, dosages of PMS and CoFe2O4/TNTs, and pH values were investigated and analyzed. Moreover, CoFe2O4/TNTs maintained its catalytic efficiency during the repeated batch experiments and also displayed functional advantages in the catalytic degradation of phenol. We believe the CoFe2O4/TNTs hybrid can be an efficient and green heterogeneous catalyst for the degradation of organic pollutants, and this study provides insights into the rational design and development of alternative catalysts for wastewater treatment.
This study demonstrates the first exploitation of zeolitic imidazolate frameworks (ZIFs) as the matrix for constructing integrated dehydrogenase-based electrochemical biosensors for in vivo ...measurement of neurochemicals, such as glucose. In this study, we find that ZIFs are able to serve as a matrix for coimmobilizing electrocatalysts (i.e., methylene green, MG) and dehydrogenases (i.e., glucose dehydrogenase, GDH) onto the electrode surface and an integrated electrochemical biosensor is readily formed. We synthesize a series of ZIFs, including ZIF-7, ZIF-8, ZIF-67, ZIF-68, and ZIF-70 with different pore sizes, surface areas, and functional groups. The adsorption capabilities toward MG and GDH of these ZIFs are systematically studied with UV–vis spectroscopy, confocal laser scanning microscopy, and Fourier transfer-infrared spectroscopy. Among all the ZIFs demonstrated here, ZIF-70 shows excellent adsorption capacities toward both MG and GDH and is thus employed as the matrix for our glucose biosensor. To construct the biosensor, we first drop-coat a MG/ZIF-70 composite onto a glassy carbon electrode and then coat GDH onto the MG/ZIF-70 composite. In a continuous-flow system, the as-prepared ZIF-based biosensor is very sensitive to glucose with a linear range of 0.1–2 mM. Moreover, the ZIF-based biosensor is more highly selective on glucose than on other endogenous electroactive species in the cerebral system. In the end, we demonstrate that our biosensor is capable of monitoring dialysate glucose collected from the brain of guinea pigs selectively and in a near real-time pattern.
The LCL-type grid-connected inverter (GCI) is widely adopted between distributed generation (DG) and power grid to realize DC/AC power conversion. However, the underdamped LCL filter will cause a ...resonance phenomenon near the control stability boundary, which may lead to instability of the GCI system. The traditional passive damping method will cause power loss, while the active damping method may have the need for additional sensors or be sensitive to parameter changes. In this article, a control scheme based on active disturbance rejection control (ADRC) is proposed for the LCL-type GCI, and the systematic parameter design method is presented through root locus analysis. With the proposed strategy, only the grid-injected current is sensed to achieve the objectives of grid-injected current direct control and robust resonance damping for the LCL-type GCI. In the design process, the influence of digital control delay and grid impedance uncertainty on system stability is explicitly analyzed in detail. Through this, the GCI can work stably over a wide range of the typical inductive-resistive grid impedance. In addition, it is found that the proposed strategy also has good adaptability to the filter parameter perturbation. Simulation and experimental results validate the theoretical analysis in this paper.
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•Fe3C@NCNTs/GNS is simply obtained by a direct pyrolysis of K4Fe(CN)6.•Fe3C@NCNTs/GNS exhibits excellent performance for Bisphenol A (BPA) degradation.•1O2 and O2− are responsible for ...BPA removal instead of classical OH and SO4−.•Graphitic carbon framework together with N doping induces the non-radical pathway.•Influences of anions, humic acid, and actual sewages are investigated in detail.
Developing novel carbocatalysts with available strategies for peroxymonosulfate (PMS) activation has become a popular topic in environmental remediation and protection fields. Herein, using commercial K4Fe(CN)6 as the precursor, Fe3C@nitrogen-doped carbon nanotubes/graphene nanosheets (Fe3C@NCNTs/GNS) is synthesized by a direct high-temperature pyrolysis. Characterization results prove that Fe3C@NCNTs/GNS has a relatively high graphitization degree and rich nitrogen doping content, which endow it with excellent catalytic efficiency in PMS activation for powerful removal of Bisphenol A (BPA). Influences of catalyst/oxidant dosages, some inorganic anions, humic acid, and practical sewages are investigated in detail. For mechanism studies, it is found that tert-butyl alcohol (TBA)/methanol fails to inhibit BPA degradation, and the primary reactive oxidative species (ROS) are superoxide radical (O2−) and singlet oxygen (1O2). Discussion on the origin of 1O2 confirms that moderate modification of N atoms in graphitic carbon frameworks plays an essential role in inducing the non-radical mechanism. This work will provide new insights for the preparation of high-performance carbocatalysts in PMS activation and exploring critical roles of N-doping during non-radical processes.
In situ pyrolysis of metal-organic frameworks (MOFs) is becoming a popular technique to construct uniform carbon-based composites with excellent performance in many research fields. In this study, ...Co/C composites derived from a zeolitic imidazolate framework, ZIF-67, are selected as novel microwave absorbers. The obtained Co/C composites with uniform polyhedron microstructure are actually composed of amorphous carbon frameworks and highly dispersed core-shell Co@graphite nanoparticles. The pyrolysis conditions are carefully optimized, and the effects of pyrolysis temperature on carbon content, graphitization degree, magnetic property, and porous structure are also investigated. It is very interesting that these Co/C composites present different dielectric loss ability and similar magnetic loss ability, resulting in their distinguishable reflection loss characteristics. Among these candidates, the Co/C composite pyrolyzed at 800 °C (Co/C-800) shows the best microwave absorption due to its dual loss mechanisms and well matched characteristic impedance. The control experiments indicate that both high-purity Co phase and ordered microstructure are indeed helpful to improving their performances. Moreover, the effective microwave absorption frequency can be further manipulated by the polyhedron size of Co/C composites, which may provide an exciting clue for the design and fabrication of lightweight and highly effective microwave absorbers in the future.
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•High-purity Co/C composites are prepared by optimizing pyrolysis of ZIF-67.•The as-prepared Co/C composites show strong microwave absorption.•Dual loss mechanism and matched impedance account for their microwave absorption.•Ordered structure and pure Co phase contribute to upgrading their performances.•The effective microwave absorption frequency can be tuned by the polyhedron size.
Background
Gut microbial metabolites have been implicated as novel risk factors for cardiovascular events and premature death. The strength and consistency of associations between blood ...concentrations of the gut microbial metabolites, trimethylamine‐N‐oxide (TMAO) and its precursors, with major adverse cardiovascular events (MACE) or death have not been comprehensively assessed. We quantified associations of blood concentrations of TMAO and its precursors with risks of MACE and mortality.
Methods and Results
PubMed and Embase databases were searched up, and a total of 19 prospective studies from 16 publications (n=19 256, including 3315 incident cases) with quantitative estimates of the associations of TMAO with the development of MACE or death were included in our main analysis. Multivariate‐adjusted relative risks (RRs) were used when these were available. Elevated concentrations of TMAO were associated with a pooled RR of 1.62 (95% CI, 1.45, 1.80; Pheterogeneity=0.2; I2=23.5%) for MACE compared with low TMAO levels, and 1 study of black participants influenced the heterogeneity of the association. After excluding the data of blacks, the RRs were not different according to body mass index, prevalence of diabetes mellitus, history of cardiovascular diseases, and kidney dysfunction. Furthermore, elevated TMAO concentrations were associated with a pooled RR of 1.63 (1.36, 1.95) for all‐cause mortality. Individuals with elevated concentrations of TMAO precursors (l‐carnitine, choline, or betaine) had an approximately 1.3 to 1.4 times higher risk for MACE compared to those with low concentrations.
Conclusions
Elevated concentrations of TMAO and its precursors were associated with increased risks of MACE and all‐cause mortality independently of traditional risk factors.
To address how the microbiome might modify the interaction between diet and cardiometabolic health, we analyzed longitudinal microbiome data from 307 male participants in the Health Professionals ...Follow-Up Study, together with long-term dietary information and measurements of biomarkers of glucose homeostasis, lipid metabolism and inflammation from blood samples. Here, we demonstrate that a healthy Mediterranean-style dietary pattern is associated with specific functional and taxonomic components of the gut microbiome, and that its protective associations with cardiometabolic health vary depending on microbial composition. In particular, the protective association between adherence to the Mediterranean diet and cardiometabolic disease risk was significantly stronger among participants with decreased abundance of Prevotella copri. Our findings advance the concept of precision nutrition and have the potential to inform more effective and precise dietary approaches for the prevention of cardiometabolic disease mediated through alterations in the gut microbiome.
A gut-microbial metabolite, trimethylamine N-oxide (TMAO), has been associated with coronary atherosclerotic burden. No previous prospective study has addressed associations of long-term changes in ...TMAO with coronary heart disease (CHD) incidence.
The purpose of this study was to investigate whether 10-year changes in plasma TMAO levels were significantly associated with CHD incidence.
This prospective nested case-control study included 760 healthy women at baseline. Plasma TMAO levels were measured both at the first (1989 to 1990) and the second (2000 to 2002) blood collections; 10-year changes (Δ) in TMAO were calculated. Incident cases of CHD (n = 380) were identified after the second blood collection through 2016 and were matched to controls (n = 380).
Regardless of the initial TMAO levels, 10-year increases in TMAO from the first to second blood collection were significantly associated with an increased risk of CHD (relative risk RR in the top tertile: 1.58 95% confidence interval (CI): 1.05 to 2.38; RR per 1-SD increment: 1.33 95% CI: 1.06 to 1.67). Participants with elevated TMAO levels (the top tertile) at both time points showed the highest RR of 1.79 (95% CI: 1.08 to 2.96) for CHD as compared with those with consistently low TMAO levels. Further, we found that the ΔTMAO-CHD relationship was strengthened by unhealthy dietary patterns (assessed by the Alternate Healthy Eating Index) and was attenuated by healthy dietary patterns (p interaction = 0.008).
Long-term increases in TMAO were associated with higher CHD risk, and repeated assessment of TMAO over 10 years improved the identification of people with a higher risk of CHD. Diet may modify the associations of ΔTMAO with CHD risk.
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There are limited therapeutic methods for triple negative breast cancer in the clinic, which is easy to progress into the brain to form metastatic lesions and evolve into the terminal stage. Because ...both the primary cancer and the brain metastasis have high glycolysis, we hypothesize that lactate dehydrogenase (LDH), which catalyzes the final step of glycolysis, may be a predictor, as well as a treatment target, for breast cancer brain metastasis. Therefore, the expression of LDH-A was detected on 119 triple negative breast cancer tissues with immunohistochemistry, and the serum LDH levels were also measured. Our results showed that the LDH-A expression inside the tumor was significantly higher than the matched normal tissues. Tumor LDH-A expression, serum LDH status, and the slope of serum LDH status were closely associated with triple negative breast cancer brain metastasis and brain metastasis free survival. This study indicates that tumor LDH and serum LDH status are two predictors for triple negative breast cancer brain metastasis.
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