Phosphor-converted white-light-emitting diodes (pc-WLED) have been extensively employed as solid-state lighting sources, which have a very important role in people's daily lives. However, due to the ...scarcity of the red component, it is difficult to realize warm white light efficiently. Hence, red-emitting phosphors are urgently required for improving the illumination quality. In this work, we develop a novel orangish-red La
GeO
:Bi
phosphor, the emission peak of which is located at 600 nm under near-ultraviolet (n-UV) light excitation. The full width at half maximum (fwhm) is 103 nm, the internal quantum efficiency (IQE) exceeds 88%, and the external quantum efficiency (EQE) is 69%. According to Rietveld refinement analysis and density functional theory (DFT) calculations, Bi
ions randomly occupy all La sites in orthorhombic La
GeO
. Importantly, the oxygen-vacancy-induced electronic localization around the Bi
ions is the main reason for the highly efficient orangish-red luminescence. These results provide a new perspective and insight from the local electron structure for designing inorganic phosphor materials that realize the unique luminescence performance of Bi
ions.
The Ultra-Violet Imaging Telescope (UVIT) is one of the payloads in ASTROSAT, the first Indian Space Observatory. The UVIT instrument has two 375 mm telescopes: one for the far-ultraviolet (FUV) ...channel (1300-1800 ), and the other for the near-ultraviolet (NUV) channel (2000-3000 ) and the visible (VIS) channel (3200-5500 ). UVIT is primarily designed for simultaneous imaging in the two ultraviolet channels with spatial resolution better than 1 8, along with provisions for slit-less spectroscopy in the NUV and FUV channels. The results of in-orbit calibrations of UVIT are presented in this paper.
Recent observations of several planet-hosting M dwarfs show that most have FUV/NUV flux ratios 1000 times greater than that of the Sun. Here we show that the atmospheric oxygen contents (O2 and O3) ...of potentially habitable planets in this type of UV environment could be 2–3 orders of magnitude greater than those of their counterparts around Sun-like stars as a result of decreased photolysis of O3, H2O2, and HO2. Thus detectable levels of atmospheric oxygen, in combination with the existence of H2O and CO2, may not be the most promising biosignatures on planets around stars with high FUV/NUV ratios such as the observed M dwarfs.
•The observed UV spectrum of some planet-hosting M dwarfs leads to different photochemistry.•It is easier to accumulate atmospheric oxygen on lifeless planets around such stars.•The accumulated oxygen could be detected and thus could form a “false positive” biosignature.
The semiconductor industry has witnessed a continuous decrease in the size of logic, memory and other computer chip components since its birth over half a century ago. The shrinking of features has ...to a large extent been enabled by the development of advanced photolithographic techniques. This review focuses on one important component of lithography, the resist, which is essentially a thin film that can generate a specific feature after an exposure and development process. Smaller features require an even more precisely focused photon, electron or ion beam with which to expose the resist. The promising light source for next generation lithography that will enable downscaling patterns to be written is extreme ultraviolet radiation (EUV), 92 eV (13.5 nm). The review mainly focuses on inorganic resists, as they have several advantages compared with traditional organic resists. In order to satisfy the throughput requirement in high volume semiconductor manufacturing, metal oxide resists with high resolution and sensitivity have been proposed and developed for EUV lithography. The progress of various inorganic resists is introduced and their properties have been summarized.
The current review aims to focus on recent progress and opportunities in inorganic photoresist materials, including their fabrication process, performance and working mechanism.
Skin cancer is the most commonly diagnosed cancer worldwide. Understanding the natural history of skin cancer provides the framework for the creation of prevention and control strategies that aim to ...reduce the skin cancer burden. Based on the target (individual vs. population), disease stage, and risk factors (modifiable vs. non-modifiable), strategies can be categorized into four levels, including health promotion (aka primordial prevention), primary prevention, secondary prevention, and tertiary prevention. This is the first of a two-part review, which will cover the epidemiology, risk factors, primordial prevention, and primary prevention of melanoma and keratinocyte skin cancers. In particular, we highlight preventive strategies centered on mitigating the impact of modifiable risk factors as well as potential interventions for health promotion and primary prevention of skin cancer. Summaries of existing recommendations, challenges, opportunities, and future directions are also discussed.
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