Explore the vast range of titles available.

Fixed bed reactor simulations are often based on a porous media model with a single energy equation for the combined fluid and solid phases. In this energy equation, an effective thermal conductivity (which takes into account both the fluid and solid properties) is typically utilized. DUO (DETCHEM und OpenFOAM) has been extended to model porous media reactions in 1D and 2D, including the effects of packed bed effective thermal conductivity and intra-particle diffusion. For the 1D model, correlations for the wall Nusselt number and the overall heat transfer coefficient are used to capture radial heat transfer effects. With these approaches, reactor simulation times have been reduced from hundreds or thousands of core hours required for 3D Particle Resolved Computational Fluid Dynamics (PRCFD), to core minutes/hours for a 2D porous media model, to core seconds/minutes for a 1D porous media model, while maintaining fidelity to the 3D CFD and experimental comparison data sets. Supporting examples include catalytic steam methane reforming, catalytic dry reforming of methane, and heat transfer in an empty tube.

Stabilizing perovskite nanocrystals (PNCs) has been a hot topic since last decade. To avoid defect formation under ambient conditions it is crucial to protect crystal lattice using enhanced surface passivation. Polymers are one of the most promising materials for protection of PNCs and generally used along with conventional ligands. In this work we demonstrate all polymer ligands-based strategy to achieve highly stable, spectra-pure green-emitting PNCs of CsPbBr 3 at room temperature. We employ combination of Polyvinylpyrrolidone (PVP) and Polyethylene glycol (PEG) polymers without the use of conventional Oleic acid and Oleylamine ligands. PNCs synthesized with only PVP emit bluish green weak PL intensity. Upon addition of PEG, PNCs exhibit giant PL enhancement and PL spectra shifted towards pure green region. Xray diffraction (XRD) and Transmission Electron Microscopy (TEM) confirms the formation of CsPbBr 3 lattice. We also studied the effect of PEG concentration and obtained an optimized sample with peak PL intensity. As an effect of proper passivation, optimized sample delivered 76% of Photoluminescence Quantum Yield (PLQY). It remained stable with up to one year under ambient conditions. It possessed robust thermal and UV stabilities. Sample retained 92.6% PL after 15 cycles of heating and cooling between 27 °C and 85 °C. Under extreme environmental conditions of 80% relative humidity and high intensity UV irradiation, sample retained 96.81% of original PL after 50 h testing. Further, we fabricated a Light Emitting Diode (LED) using optimized sample. The LED delivered outstanding performance with peak luminous efficiency of 104.33 lm.W − 1 (20 mA, 2.54 V) and high spectral stability after 500 h of continuous operation with 94% of PL retention. We believe this all-polymer passivation strategy could be beneficial for stabilization of perovskite materials for the next generation display devices.

Ni 0.5 Zn 0.5− x Cu x Fe 2 O 4 ( x   =  0, 0.05, 0.1, 0.15, 0.2, 0.25) spinel ferrite nanoparticles were synthesized via the sol-gel auto-combustion method and sintered at 700°C for 5 h. Thermogravimetric and differential thermal analysis (TG-DTA) revealed the thermal decomposition behaviour. Single phase ferrite with Fd ‑3 m space group was confirmed by the Rietveld refinement of X-ray diffraction data. The distribution of cation among octahedral B and tetrahedral A-site was estimated by the computational method. With increasing copper substitution, the lattice parameter decreased while X-ray density increased. Crystallite sizes ranged from 22 to 24 nm, consistent with the Williamson–Hall method, and strain decreased. Fourier-transform infrared (FTIR) spectroscopy confirmed the spinel structure. High-resolution transmission electron microscopy (HR-TEM) and field emission scanning electron microscopy (FE-SEM) showed grain sizes between 70 and 130 nm. Energy dispersive X-ray (EDAX) analysis confirmed chemical purity. Magnetic studies showed an increase in saturation magnetization and coercivity (42 to 57 Oe) with copper substitution, while dielectric behaviour followed the Maxwell–Wagner model.