Generating kidney models of T1N0M0 tumors with 3D printing are feasible with refinements to be performed. Face and content validity was obtained when those models were presented to experienced urologists for making practical planning and training. Understandings of the disease and procedure from patients were well appreciated with this novel technology.
One of the major questions in a catalytically enhanced NaAlH4 system used for hydrogen storage that remains is where catalysts like Ti/Ce reside and present as what form improving the kinetics and reversible hydrogen storage performance. In the present study, by directly introducing Ce−Al species with a structure of CeAl2 into NaAlH4, a dramatic enhancement in the hydrogen release and uptake kinetics of NaAlH4 was achieved. CeAl2-doped NaAlH4 can be reloaded 4.9 wt % hydrogen at moderate conditions in 20 min, which is among the highest values ever reported for NaAlH4. Besides, the material exhibits an exceptional performance under low pressures. For example, a capacity of more than 4.0 wt % hydrogen can be achieved at a hydrogen pressure as low as 4.0 MPa. The apparent activation energy of NaAlH4 doped with 2 mol % CeAl2 is estimated to be 72.3−90.4 kJ/mol and 93.6−98.9 kJ/mol for the first and the second dehydrogenation step respectively by using Kissinger’s approach, much lower than those of pristine NaAlH4. After prolonged cycling, the Ce−Al species transforms to a more stable species of CeAl4. On the basis of these findings and the previous investigations, the active species and mechanism of catalysis in doped NaAlH4 were discussed.
Magnesium hydride (MgH) exhibits long-term stability and has recently been developed as a safe alternative to store hydrogen in the solid state, due to its high capacity of 7.6 wt% H and low cost compared to other metal hydrides. However, the high activation energy and poor kinetics of MgH lead to inadequate hydrogen storage properties, resulting in low energy efficiency. Nano-catalysis is deemed to be the most effective strategy in improving the kinetics performance of hydrogen storage materials. In this work, robust and efficient architectures of carbon-wrapped transition metal (Co/C, Ni/C) nanoparticles (8-16 nm) were prepared and used as catalysts in the MgH system via ball milling to improve its de/rehydrogenation kinetics. Between the two kinds of nano-catalysts, the Ni/C nanoparticles exhibit a better catalytic efficiency. MgH doped with 6% Ni/C (MgH-6%Ni/C) exhibits a peak dehydrogenation temperature of 275.7 °C, which is 142.7, 54.2 and 32.5 °C lower than that of commercial MgH, milled MgH and MgH doped with 6% Co/C (MgH-6%Co/C), respectively. MgH doped with 6% Ni/C can release about 6.1 wt% H at 250 °C. More importantly, the dehydrogenated MgH-6%Ni/C is even able to uptake 5.0 wt% H at 100 °C within 20 s. Moreover, a cycling test of MgH doped with 8% Ni/C demonstrates its excellent hydrogen absorption/desorption stability with respect to both capacity (up to 6.5 wt%) and kinetics (within 8 min at 275 °C for dehydrogenation and within 10 s at 200 °C for rehydrogenation). Mechanistic research reveals that the in situ formed MgNi and MgNiH nanoparticles can be regarded as advanced catalytically active species in the MgH-Ni/C system. Meanwhile, the carbon attached around the surface of transition metal nanoparticles can successfully inhibit the aggregation of the catalysts and achieve the steadily, prompting de/rehydrogenation during the subsequent cycling process. The intrinsic catalytic effects and the uniform distributions of MgNi and MgNiH result in a favorable catalytic efficiency and cycling stability. Nano-catalysts with this kind of morphology can also be applied to other metal hydrides to improve their kinetics performance and cycling stability.
Fluorescent quantum dots (QDs) of carbon and semiconductors have superior optical properties and show great potential in sensing applications. This paper reports a novel method for rapid detection of uranyl ions via ratiometric fluorescence signals by employing two types of QDs as the key materials. As the most soluble and stable toxic uranium species, uranyl has been recognized as an important index for nuclear industrial wastewater. However, its on-site, rapid, and sensitive determination remains challenging. This work uses the ratiometric fluorescent signal of QDs and combines a smartphonebased handheld device for on-site and rapid detection of uranyl. The ratiometric fluorescent probe is achieved by integrating carbon dots (Cdots) and CdTe QDs (MPA@CdTe QDs) through chemical hybridization. The presence of uranyl ions greatly quenches the red fluorescence of the CdTe QDs, whereas the green fluorescence keeps constant, leading to an obvious color change. An app and a 3D-printed accessory have been developed on a smartphone to analyze and calculate the content of uranyl on the basis of captured fluorescence signals from a test strip with an immobilized probe. This new designed mobile detection system displays good analytical performance for uranyl ions in a wide concentration range of 1 to 150 μM, which shows a great potential application in controlling the nuclear industrial pollution.
LiBH 4 has been loaded into a highly ordered mesoporous carbon scaffold containing dispersed NbF 5 nanoparticles to investigate the possible synergetic effect of nanoconfinement and nanocatalysis on the reversible hydrogen storage performance of LiBH 4 . A careful study shows that the onset desorption temperature for nanoconfined LiBH 4 @MC-NbF 5 system is reduced to 150 °C, 225 °C lower than that of the bulk LiBH 4 . The activation energy of hydrogen desorption is reduced from 189.4 kJ mol −1 for bulk LiBH 4 to 97.8 kJ mol −1 for LiBH 4 @MC-NbF 5 sample. Furthermore, rehydrogenation of LiBH 4 is achieved under mild conditions (200 °C and 60 bar of H 2 ). These results are attributed to the active Nbcontaining species (NbH x and NbB 2 ) and the function of F anions as well as the nanosized particles of LiBH 4 and high specific surface area of the MC scaffold. The combination of nanoconfinement and nanocatalysis may develop to become an important strategy within the nanotechnology for improving reversible hydrogen storage properties of various complex hydrides.
5As anode materials for lithium ion batteries, metal oxides have a large storage capacity. However, their cycle life and rate capability are still not suitable for commercial applications. Herein, 3D hierarchical Fe 3 O 4 spheres associated with a 5-10 nm carbon shell were designed and fabricated. In the constructed architecture, the thin carbon shells can avoid the direct exposure of encapsulated Fe 3 O 4 to the electrolyte and preserve the structural and electrochemical integrity of spheres as well as inhibit the aggregation of 10 pulverized Fe 3 O 4 during electrochemical cycling. While the hierarchical structure formed by bottom-up self-assembly approach can efficiently accommodate the mechanical stress induced by the severe volume variation of Fe 3 O 4 during lithiation/delithiation processes. Moreover, the carbon shell together with the structure integrity and durability endows the favorable high conductivity and efficient ion transport. All of these features are critical for high-performance anodes, therefore enables an outstanding lithium storage 15 performance with long cycle lifespan. For instance, such an electrode could deliver a capacity of 910 mAh g -1 even after 600 cycles with a discharge/charge rate of 1 A g -1 . In addition, this effective strategy may be readily extended to construct many other classes of hybrid electrode materials for highperformance lithium-ion batteries 65 nanostructures. [1a, 2b, 4a, 6b, 16] By coating a thin carbon layer on the iron oxide nanostructures, which accounts for limited weight percent, significantly enhanced electrochemical performance can be achieved. The carbon can promote the electron transport in the poorly conductive iron oxide, form a stable SEI film and 70
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