A simple Zn/Fe bimetallic zeolitic-imidazolite framework (ZIF) carbonization method is developed to synthesize an Fe-N-C hybrid with hierarchical nitrogen-doped porous carbons crossed by carbon ...nanotubes. Both the specific ratios of Zn/Fe in the bimetallic metal-organic framework (MOF) precursors and the selected annealing temperature are essential for the formation of this unique hybrid structure with good conductivity and exposure of more active sites. The resulting FeNC-20-1000 hybrid electrocatalyst exhibits excellent oxygen reduction reaction (ORR) activity, with a half-wave potential of 0.770 V comparable to that of the commercial Pt/C catalysts in acidic media, and a half-wave potential of 0.880 V, ca. 50 mV more positive than that of Pt/C for ORR in alkaline solution. More importantly, the as-prepared Fe-N-C hybrid exhibits much more stability for the ORR in both acidic and alkaline solutions than Pt/C, which makes it among the best non-noble-metal catalysts ever reported for ORR under acidic and alkaline conditions.
Exploring highly efficient electrocatalysts and understanding the reaction mechanisms for hydrogen electrocatalysis, including hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) ...in alkaline media are conducive to the conversion of hydrogen energy. Herein, we reported a new strategy to boost the HER/HOR performances of ruthenium (Ru) nanoparticles through nitrogen (N) modification. The obtained N-Ru/C exhibit remarkable catalytic performance, with normalized HOR exchange current density and mass activity of 0.56 mA/cm2 and 0.54 mA/µg, respectively, about 4 and 4.5 times higher than those of Ru/C, and even twofold enhancement compared to commercial Pt/C. Moreover, at the overpotential of 50 mV, the normalized HER current density of N-Ru/C is 5.5 times higher than that of Ru/C. Experimental and density functional theory (DFT) results verify the electronic regulation of Ru after N incorporation, resulting in the optimized hydrogen adsorption Gibbs free energy (ΔGH*) and hence enhancing the HOR/HER performance.
The catalytic performance of Ru nanoparticles toward hydrogen oxidation reaction and hydrogen evolution reaction (HOR/HER) under alkaline media can be significantly enhanced through surface N modification. Experimental and density functional theory (DFT) calculation results indicate the enhanced HOR/HER performances are derived from optimized hydrogen adsorption Gibbs free energy (ΔGH*) of N-Ru/C after N incorporation. Display omitted
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Rupture of emerging tough hydrogels has received much attention in recent years. It is a fundamental question what length of initial flaws can significantly affect the rupture of a tough hydrogel. ...Here we study the rupture of a tough hydrogel, using samples with and without initial cuts, under monotonic and cyclic loads. We prepare six samples under the same conditions, either without initial cut, or with initial cuts of the same length, and load them monotonically to inspect the statistical variation of measured rupture stress, rupture stretch and work of rupture. We cycle the six samples in parallel to the same amplitude of stretch and record the number of cycles to rupture of each sample. The average number of cycles to rupture decreases with the amplitude of stretch; and an endurance stretch exists, below which the samples can sustain indefinite number of cycles without rupture. We find that when the initial cut is long, the endurance stretch decreases with the initial cut length. When the initial cut is short, the endurance stretch is insensitive to the initial cut length. We interpret this finding by a material-specific length, the endurance fractocohesive length. We compare the endurance fractocohesive lengths of the hydrogel and other materials, including elastomers, plastics, metals, and ceramics. It is hoped that similar experiments will be soon conducted for other hydrogels to guide their development.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Detailed behavioral analysis is key to understanding the brain-behavior relationship. Here, we present deep learning-based methods for analysis of behavior imaging data in mice and humans. ...Specifically, we use three different convolutional neural network architectures and five different behavior tasks in mice and humans and provide detailed instructions for rapid implementation of these methods for the neuroscience community. We provide examples of three dimensional (3D) kinematic analysis in the food pellet reaching task in mice, three-chamber test in mice, social interaction test in freely moving mice with simultaneous miniscope calcium imaging, and 3D kinematic analysis of two upper extremity movements in humans (reaching and alternating pronation/supination). We demonstrate that the transfer learning approach accelerates the training of the network when using images from these types of behavior video recordings. We also provide code for post-processing of the data after initial analysis with deep learning. Our methods expand the repertoire of available tools using deep learning for behavior analysis by providing detailed instructions on implementation, applications in several behavior tests, and post-processing methods and annotated code for detailed behavior analysis. Moreover, our methods in human motor behavior can be used in the clinic to assess motor function during recovery after an injury such as stroke.
A group of ionic liquid (IL)-based polyoxometalate (POM) salts were prepared via anion-exchange of imidazolium IL precursors tethered by different carbon chain alkyls with various Keggin POMs. The ...resultant imidazolium POM salts were tested as the catalysts for oxidation of sulfides with aqueous H2O2. For understanding the POM salt-catalyzed oxidation of sulfides, catalyst compositions, substrates, and reaction conditions were changed. The results show that the imidazolium POM salts are very active and selective heterogeneous catalysts for oxidations of sulfides, adding the advantages of convenient recovery, steady reuse, simple preparation, and flexible composition. Characterizations by Fourier transform infrared (FT-IR), ultraviolet–visible (UV–vis), X-ray diffraction (XRD), and elemental analysis further reveal that the heterogeneous nature of the oxidation processes associates with the good crystallinities of the butyl- and hexyl-functionalized imidazolium POM salts and the hydrogen bonding networks among cations and anions. The POM salts’ excellent performances arise from the promoted redox property of the POM-anions by the intramolecular charge transfer from the IL-cations.
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IJS, KILJ, NUK, PNG, UL, UM
In this article, we study the system of Klein-Gordon and Born-Infeld equations $$\displaylines{ -\Delta u +V(x)u-(2\omega+\phi)\phi u =f(x,u), \quad x\in \mathbb{R}^3,\cr \Delta ...\phi+\beta\Delta_4\phi=4\pi(\omega+\phi)u^2, \quad x\in \mathbb{R}^3, }$$ where \(\Delta_4\phi=\hbox{div}(|\nabla\phi|^2\nabla\phi)$\), \(\omega\) is a positive constant. Assuming that the primitive of \(f(x,u)\) is of 2-superlinear growth in \(u\) at infinity, we prove the existence of multiple solutions using the fountain theorem. Here the potential \(V\) are allowed to be a sign-changing function.
For more information see https://ejde.math.txstate.edu/Volumes/2024/18/abstr.html
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
In the context of the ever-increasing energy crisis, electrocatalytic water splitting has attracted widespread attention as an effective means to provide clean energy. However, the oxygen evolution ...reaction (OER), which is an important anodic half reaction, shows very slow kinetics due to the multi-step electron transfer process, which severely restricts the efficiency of energy conversion. Herein, we used a simple solvothermal method to dope iron into the cobalt-containing hydroxide precursor, and successfully prepared the Fe-doped Co-oxide electrocatalyst Co
Fe
O
-0.01. It only needs an overpotential of 294 mV to perform the OER at a current density of 10 mA cm
, and has a low Tafel slope of 47.3 mV dec
. Moreover, Co
Fe
O
-0.01 has excellent stability. There is no significant increase in the overpotential for oxygen evolution at a current density of 10 mA cm
after nearly 20 h. BET surface area test and XPS spectroscopy results show that Fe doping provides more mesopores and oxygen bridges, which is conducive to the construction of active sites and electronic regulation during the OER. This work can help design more bimetallic based highly active OER materials.
Polyoxometalate(POM)-based ionic hybrid nanospheres prepared by protonating and anion-exchanging amino-attached ionic liquid cations with Keggin POM-anions have proven to be highly efficient ...heterogeneous catalysts for the epoxidation of alkenes with H2O2, presenting advantages of convenient recovery, steady reuse, simple preparation, and flexible composition.
Aiming at the impact of heat generation and temperature rise on the driving performance of a permanent magnet (PM) motor, taking the PM in-wheel motor (IWM) for electric vehicles as an object, ...research is conducted into the temperature distribution of the electromagnetic–thermal effect and cooling structure optimization. Firstly, the electromagnetic–thermal coupling model considering electromagnetic harmonics is established using the subdomain model and Bertotti’s iron loss separation theory. Combined with the finite element (FE) simulation model established by Ansoft Maxwell software platform, the winding copper loss, stator core loss and PM eddy current loss under the action of complex magnetic flux are analyzed, and the transient temperature distribution of each component is obtained through coupling. Secondarily, the influence of the waterway structure parameters on the heat dissipation effect of the PM-IWM is analyzed by the thermal-fluid coupled relationship. On the basis, the optimization design of waterway structure parameters is carried out to improve the heat dissipation effect of the cooling system based on the proposed chaotic mapping ant colony algorithm with metropolis criterion. The comparison before and after optimization shows that the temperature of key components is significantly improved, the average convection heat transfer coefficient (CHTC) is increased by 23.57%, the peak temperature of stator is reduced from 95.47 °C to 82.73 °C, and the peak temperature of PM is decreased by 14.26%, thus the demagnetization risk in the PM is improved comprehensively. The research results can provide some theoretical and technical support for the structural optimization of water-cooled dissipation in the PM motor.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Due to its high acidity and toxic metal content, acid mine drainage (AMD) needs to be properly treated before being discharged into the environment. This study took the AMD collected from one ...specific mine in China as a sample and investigated the treatment methodology for AMD. The water quality of the AMD was measured, and the sample was treated with caustic soda (NaOH) and shell powder (one kind of conventional neutralizer, mainly composed of CaCO3) by the neutralization method. The results show that the AMD has a relatively low pH (2.16) and contains high concentrations of Fe (77.54 g/L), Mn (621.29 mg/L), Cu (6.54 mg/L), Ca (12.39 mg/L), and Mg (55.04 mg/L). NaOH was an effective neutralizer to treat the AMD and performed much better than shell powder. Various metals were precipitated, in the order of Fe(III), Cu, Fe(II), Mn, Ca, and Mg. The metal removal mechanisms included precipitation, adsorption, and co-precipitation. The optimal reaction conditions were the reaction duration was selected as 5 min and the mass ratio of NaOH to AMD was 0.16:1 (w:v). By this stage, the pH rapidly increased from 2.16 to 8.53 during AMD-NaOH interactions and various metals were efficiently removed (from 86.71% to 99.99%) by NaOH. The residual mass concentrations of Fe, Mn, Cu, Ca, and Mg after the treatment were 1.52, 1.77, 0.10, 1.65, and 2.17 mg/L, respectively. These data revealed that NaOH was a good treatment regent for this kind of AMD, based on the discharge criteria of China (GB28661 2012). Also, the shell powder was a helpful neutralizer for pH adjustment and copper removal. This neutralization method has the advantages of convenient operation, high speed, good effect, simple equipment, and low infrastructure cost. In addition, the resulting neutralized residue is a valuable and high-quality raw material, which can be used in metal smelting and separation.
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