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Errors are introduced when using traditional methods for measuring the total luminous flux of LEDs since an LED is quite different from traditional light sources in terms of physical size, flux level, spectrum and spatial distribution. This paper uses commercial lighting simulation software named Tracepro to simulate the self-absorption effect when using traditional integrating sphere methods to measure the total luminous flux of LEDs and then presents a modified method for the measurement. The LED under investigation or a specially designed narrow beam standard lamp is placed on the interior wall of the sphere in our method. The results show that the measurement method presented here can lead to better precision in the evaluation of the total luminous flux of LEDs.

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Magnetic materials show promising applications in heterogeneous catalysis because of their ease of separation and good reusability. The present work reports the design, synthesis, and characterization of a novel magnetic biochar supported nickel catalyst. Fourier infrared spectroscopy (FT‐IR), powder X‐ray diffraction technology (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM) techniques were used for analyzing the prepared catalyst. The prepared catalyst exhibited excellent catalytic activity for synthesis of spirooxindole‐dihydropyridines derivatives by a one‐pot three‐component reaction of isatin, barbituric acid, and 6‐amino uracil or 1H‐pyrazol‐5‐amine. This new methodology demonstrated some important features, including high yields, lower loading of the catalyst, easy work‐up, and recyclability of the catalyst for a minimum of six times without an obvious decay of catalytic performance.