A real optimal Fe content: For N and Fe co‐doped carbon electrocatalysts for oxygen reduction reactions (ORRs) it is found that there is a real optimal trace Fe content (Peak II), which has never ...been observed before. The real optimal electrocatalyst shows superior high activity for ORR and possesses the best price/performance ratio ever.
For the goal of practical industrial development of fuel cells, inexpensive, sustainable, and high performance electrocatalysts for oxygen reduction reactions (ORR) are highly desirable alternatives ...to platinum (Pt) and other rare materials. In this work, sustainable fluorine (F)-doped carbon blacks (CB-F) as metal-free, low-cost, and high-performance electrocatalysts for ORR were synthesized for the first time. The performance (electrocatalytic activity, long-term operation stability, and tolerance to poisons) of the best one (BP-18F, based on Black Pearls 2000 (BP)) is on the same level as Pt-based or other best non-Pt-based catalysts in alkaline medium. The maximum power density of alkaline direct methanol fuel cell with BP-18F as the cathode (3 mg/cm2) is ∼15.56 mW/cm2 at 60 °C, compared with a maximum of 9.44 mW/cm2 for commercial Pt/C (3 mgPt/cm2). All these results unambiguously demonstrate that these sustainable CB-F catalysts are the most promising alternatives to Pt in an alkaline fuel cell. Since sustainable carbon blacks are 10 000 times less expensive and much more abundant than Pt or other rare materials, these CB-F electrocatalysts possess the best price/performance ratio for ORR to date.
For the goal of practical industrial development of fuel cells, cheap, sustainable and high performance electrocatalysts for oxygen reduction reactions (ORR) which rival those based on platinum (Pt) ...and other rare materials are highly desirable. In this work, we report a class of cheap and high-performance metal-free oxygen reduction electrocatalysts obtained by co-doping carbon blacks with nitrogen and fluorine (CB-NF).The CB-NF electrocatalysts are highly active and exhibit long-term operation stability and tolerance to poisons during oxygen reduction process in alkaline medium. The alkaline direct methanol fuel cell with the best CB-NF as cathode (3 mg/cm(2)) outperforms the one with commercial platinum-based cathode (3 mg Pt/cm(2)). To the best of our knowledge, these are among the most efficient non-Pt based electrocatalysts. Since carbon blacks are 10,000 times cheaper than Pt, these CB-NF electrocatalysts possess the best price/performance ratio for ORR, and are the most promising alternatives to Pt-based ones to date.
Context: In vitro and in vivo research has shown that curcumin can alleviate diabetes and the relevant complications.
Objective: To investigate the effect of curcumin on gestational diabetes (GD).
...Materials and methods: C57 BL/KsJ
db
/+
(db/+) mice and C57 BL/KsJ
+/+
mice (10-12 weeks old) were divided into four groups (n = 15): normal pregnancy (C57 BL/KsJ
+/+
), GD (C57 BL/KsJ
db
/+
), GD plus low dose curcumin (50 mg/kg, orally gavage every day) and GD plus high dose curcumin (100 mg/kg, orally gavage every day). The tolerance of glucose and insulin were measured on gestation day 10. Body weight at birth and litter size of offspring were investigated, and the expression of oxidative stress factors thiobarbituric acid reactive substance (TBARS), glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) and AMP-activated protein kinase (AMPK), phospho-AMPK, histone deacetylases 4 (HDAC4), pHDAC4 and glucose-6-phosphatase (G6Pase) in the livers were analyzed by ELISA and Western blot on gestation day 20.
Results: High dose curcumin could partly ameliorate the intolerance of glucose and insulin, and completely restore the litter size and the body weight of GD mice through decreased TBARS expression (p < 0.05) and increased GSH, SOD and CAT expression (p < 0.05). Enhanced AMPK activation, accompanied with decreased HDAC4 and G6Pase expression (p < 0.05) were partly contributed to the alleviation of GD mediated by curcumin.
Conclusions: Although further detailed mechanism needs to be deciphered, curcumin can be considered as an alternative treatment for gestational diabetes.
Fluorine-decorated nickel iron layered double hydroxides electrocatalyst with partially amorphous feature, abundant oxygen vacancies, as well as the effortless dissociated metal-F ionic bond ...demonstrates excellent catalytic activity toward alkaline urea oxidation reaction.
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The urea oxidation reaction (UOR) has been well-acknowledged as one of the promising alternatives for hydrogen production through electrochemical water splitting system because of the more favorable thermodynamic potential. But the shortage of cost-effective electrocatalysts with high catalytic activity and durability restricts its practical development. Herein, the partially amorphous fluorine-decorated nickel iron layered double hydroxides (NiFe-F) is constructed via a low-temperature fluoridation method. Our study found that HF acid etching of NiFe LDH precursor resulted in the partially amorphous feature and abundant oxygen vacancies, providing rich reaction sites. Simultaneously, the formation of ionic metal-F bond makes it easier to form high-valence metal oxygen hydroxide active sites. Specifically, the as-prepared NiFe-F-4 electrode demonstrates a superb mass activity of 1290 mA mg−1 at 1.6 V vs. RHE. Further experiments found that amorphous structure and F decorating decreased the activation energy of UOR from 30.71 kJ mol−1 (crystalline NiFe-F-4) to 20.17 kJ mol−1 (amorphous NiFe-F-4), leading to a rapid dynamic with a small Tafel slope of 31 mV dec-1. Moreover, NiFe-F-4 casts remarkable long-term durability for 40 h without performance decay. This work holds great promise to develop advanced electrocatalysts for pollution treatment of urea-rich wastewater and energy-saving H2 production.
Simulated sunlight has promise as a light source able to alleviate the severe pain associated with patients during photodynamic therapy (PDT); however, low sunlight utilization efficiency of ...traditional photosensitizers dramatically limits its application. Titanium‐dioxide‐nanoparticle–gold‐nanocluster–graphene (TAG) heterogeneous nanocomposites are designed to efficiently utilize simulated sunlight for melanoma skin cancer PDT. The narrow band gap in gold nanoclusters (Au NCs), and staggered energy bands between Au NCs, titanium dioxide nanoparticles (TiO2 NPs), and graphene can result in efficient utilization of simulated sunlight and separation of electron–hole pairs, facilitating the production of abundant hydroxyl and superoxide radicals. Under irradiation of simulated sunlight, TAG nanocomposites can trigger a series of toxicological responses in mouse B16F1 melanoma cells, such as intracellular reactive oxygen species production, glutathione depletion, heme oxygenase‐1 expression, and mitochondrial dysfunctions, resulting in severe cell death. Furthermore, intravenous or intratumoral administration of biocompatible TAG nanocomposites in B16F1‐tumor‐xenograft‐bearing mice can significantly inhibit tumor growth and cause severe pathological tumor tissue changes. All of these results demonstrate prominent simulated sunlight‐mediated PDT effects.
TiO2‐nanoparticle (NP)–Au‐nanocluster (NC)–graphene (TAG) nanocomposites are designed for sunlight‐triggered photodynamic therapy for melanoma skin cancer. With simulated sunlight radiation, the narrow band gap of Au NCs, the excellent electronic property of graphene, and staggered energy bands between Au NCs, TiO2 NPs, and graphene can efficiently utilize sunlight and prompt electron–hole separation, producing abundant radicals to damage cells and inhibit tumor growth.
The {101}–{001} surface heterojunction constructed on polyhedral titanium dioxide (TiO2) nanocrystals has recently been proposed to be favorable for the efficient electron–hole spatial separation due ...to the preferential accumulation of electron and hole on {101} and {001} facets, respectively. The formed free electron and hole can promote reactive oxygen species (ROS) production, which potentially can be used for inactivation of bacteria. In the present study, a series of truncated octahedral bipyramid TiO2 nanocrystals (T1, T2, T3, and T4) coexposed with {101} and {001} facets were prepared to form various ratios of {101} to {001} facet for optimization of electron–hole spatial separation efficiency. All these polyhedral TiO2 nanocrystals could more significantly produce ROS than spherical TiO2 nanocrystals (Ts), exhibiting the higher antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria under simulated sunlight irradiation. Among these polyhedral TiO2 nanocrystals, T3 with a {101}/{001} ratio of 1.78 was found to be the best one showing the highest ROS and the most potent antibacterial performance. Scanning electron microscope images of bacteria displayed that the surface membrane structure of both E. coli and S. aureus bacteria was influenced to different extents by these TiO2 nanocrystals, where T3 caused the most severe membrane damage. The molecular mechanism underlying the high antibacterial activity of TiO2 nanocrystals was ascribed to activation of oxidative stress as evidenced by intracellular ROS production, glutathione depletion, and membrane lipid peroxidation in bacteria. The surface heterojunction as a completely new strategy holds great promise to develop effective antibacterial nanomaterials.
Under the relentless neoliberalism, there is a growing claim that doctoral students have transformed into highly performative, enterprising, and self-reliant subjects in the current higher education ...landscape. Whilst this seems almost a truism to encapsulate the unprecedentedly competitive educational context in which the PhD is pursued, it is equally important to recognise the diversified profiles of doctoral individuals. Against this backdrop, the study draws upon Archer’s critical realist theory to conceptualise the heterogeneity and complexity of eighteen doctoral students’ experiences with/in the neoliberal university and academy. Using Archer’s reflexive modality as an inclusive framework, analysis has detected the positive linkage between participants’ preferable deployment of particular mode(s) of reflexivity and the prototypical way they steer their PhD trajectories taking a multiplicity of forms. As such, the study makes original contribution to existing literature in three aspects. First, in illuminating the differential concerns participants hold about the PhD pursuit, it suggests that the prevailing neoliberal forces do not invariably produce damaging impacts, nor are they inescapable for all candidates. Second, analysis highlights that whilst participants with a great clarity of value commitments and career goals at the beginning of their PhD can consistently translate their reflexivity into agentic action, this is not a commonplace experience. Third, the finding on participants’ practice of hybrid and shifting reflexive modes throws into relief the limits of Archer’s thesis, which tends to champion a fixed conception of reflexivity and downplay structural influences on the mode of reflexivity one employs. In view of these insights, the study culminates in pointing towards more promising lines of inquiry alongside presenting a set of practical implications.
DNA barcodes enable Oxford Nanopore sequencing to sequence multiple barcoded DNA samples on a single flow cell. DNA sequences with the same barcode need to be grouped together through demultiplexing. ...As the number of samples increases, accurate demultiplexing becomes difficult. We introduce HycDemux, which incorporates a GPU-parallelized hybrid clustering algorithm that uses nanopore signals and DNA sequences for accurate data clustering, alongside a voting-based module to finalize the demultiplexing results. Comprehensive experiments demonstrate that our approach outperforms unsupervised tools in short sequence fragment clustering and performs more robustly than current state-of-the-art demultiplexing tools for complex multi-sample sequencing data.
Nitrogen-doped acetylene carbon black (N-C) is prepared by annealing acetylene carbon black and melamine under the protection of N2 at different temperatures. The resultant N-C materials are used as ...the support of Pd catalyst (Pd/N-C) for formic acid electrooxidation (FAEO). The catalytic activity of the Pd/N-C catalyst towards FAEO is evaluated by cyclic voltammetry, COad stripping voltammetry and chronoamperometry. The results show that when the heat-treatment temperature of support is 900 °C, the corresponding catalyst, Pd/N-C-900, generate 2.84-fold and 0.96-fold higher activity than homemade and commercial Pd/C catalysts in 0.5 M H2SO4 and 0.5 M HCOOH solution. The COad stripping voltammetry results demonstrate that Pd/N-C-900 has much better resistance to CO poisoning. Moreover, the effect of formic acid concentration and the temperature on the Pd/N-C catalysts are also explored, which confirms the really enhanced performances for FAEO. It is founded that the doping of nitrogen results an increase in the performance for FAEO due to the improved Pd nanoparticles (Pd NPs) dispersion and the modified electronic effect. The results indicate that the Pd/N-C catalyst has great application prospect as a high-performance anode catalyst for direct formic acid fuel cells (DFAFCs).
•Palladium nanoparticles supported on the N-doped carbon materials used for FAEO.•Pd/N-C-900 catalyst shows the best catalytic activity and stability for FAEO.•Syngenetic effect of catalyst and support proposed for the catalytic process.
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