Adaptive camouflage in thermal imaging, a form of cloaking technology capable of blending naturally into the surrounding environment, has been a great challenge in the past decades. Emissivity engineering for thermal camouflage is regarded as a more promising way compared to merely temperature controlling that has to dissipate a large amount of excessive heat. However, practical devices with an active modulation of emissivity have yet to be well explored. In this letter we demonstrate an active cloaking device capable of efficient thermal radiance control, which consists of a vanadium dioxide (VO2) layer, with a negative differential thermal emissivity, coated on a graphene/carbon nanotube (CNT) thin film. A slight joule heating drastically changes the emissivity of the device, achieving rapid switchable thermal camouflage with a low power consumption and excellent reliability. It is believed that this device will find wide applications not only in artificial systems for infrared camouflage or cloaking but also in energy-saving smart windows and thermo-optical modulators.

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Two light-emitting diode samples are grown with InGaN and GaN underlying layers beneath the multiple quantum wells (MQWs), respectively. By measuring the carrier lifetime as a function of photon energy, it is found that the MQW with InGaN underlying layer has a higher degree of carrier localization. Comparison between the external quantum efficiency and injection current of these two samples reveals that efficiency droop at small injection current is attributed to the delocalization of carriers, while further droop at a higher injection current is due mostly to the carrier leakage demonstrated through temperature-dependent electroluminescence measurements.

Electrochromic devices with tunable infrared radiation can meet the steadily growing demands in energy saving and thermal camouflage applications. Here, a mid-infrared radiation modulator based on flexible multilayer graphene thin films gated by nonvolatile ionic liquid on both rigid and flexible substrates is designed. The thermal emissivity of the device decreases nearly 80% within 2 s with the accumulation of anions in the multilayer graphene. The effective reduction of the emissivity results from the dramatic decrease in film's intraband absorption of graphene according to the Drude model. It has been demonstrated that with electrical control the film's midinfrared radiation is capable of adapting to different backgrounds for thermal camouflage applications. Moreover, a sandwiched structure with stacked graphene films is designed to realize structural flexibility and double-sided radiation control for a wide range of potential applications, including energyefficient buildings, infrared sources, and electrochromic displays.

In this work, we reported a simple rapid and point-of-care magnetic immunofluorescence assay for avian influenza virus (AIV) and developed a portable experimental setup equipped with an optical fiber spectrometer and a microfluidic device. We achieved the integration of immunomagnetic target capture, concentration, and fluorescence detection in the microfluidic chip. By optimizing flow rate and incubation time, we could get a limit of detection low up to 3.7 × 10(4) copy/μL with a sample consumption of 2 μL and a total assay time of less than 55 min. This approach had proved to possess high portability, fast analysis, high specificity, high precision, and reproducibility with an intra-assay variability of 2.87% and an interassay variability of 4.36%. As a whole, this microfluidic system may provide a powerful platform for the rapid detection of AIV and may be extended for detection of other viral pathogens; in addition, this portable experimental setup enables the development of point-of-care diagnostic systems while retaining adequate sensitivity.

In this work, robust approach for a highly sensitive point-of-care virus detection was established based on immunomagnetic nanobeads and fluorescent quantum dots (QDs). Taking advantage of immunomagnetic nanobeads functionalized with the monoclonal antibody (mAb) to the surface protein hemagglutinin (HA) of avian influenza virus (AIV) H9N2 subtype, H9N2 viruses were efficiently captured through antibody affinity binding, without pretreatment of samples. The capture kinetics could be fitted well with a first-order bimolecular reaction with a high capturing rate constant k(f) of 4.25 × 10(9) (mol/L)(-1) s(-1), which suggested that the viruses could be quickly captured by the well-dispersed and comparable-size immunomagnetic nanobeads. In order to improve the sensitivity, high-luminance QDs conjugated with streptavidin (QDs-SA) were introduced to this assay through the high affinity biotin-streptavidin system by using the biotinylated mAb in an immuno sandwich mode. We ensured the selective binding of QDs-SA to the available biotin-sites on biotinylated mAb and optimized the conditions to reduce the nonspecific adsorption of QDs-SA to get a limit of detection low up to 60 copies of viruses in 200 μL. This approach is robust for application at the point-of-care due to its very good specificity, precision, and reproducibility with an intra-assay variability of 1.35% and an interassay variability of 3.0%, as well as its high selectivity also demonstrated by analysis of synthetic biological samples with mashed tissues and feces. Moreover, this method has been validated through a double-blind trial with 30 throat swab samples with a coincidence of 96.7% with the expected results.

Heteroepitaxy of high-quality AlN film is the key to advance the prosperity of deep-ultraviolet (DUV) devices when a large-size and low-cost native substrate is unavailable. Here, we proposed a strategy to obtain high-quality AlN film by combining growth-mode modification with sputtered AlN buffer using metal− organic chemical vapor deposition (MOCVD). Compared with the MOCVD AlN buffer, the sputtered AlN buffer consists of smaller and more uniform grains with better c-axis orientation, leading to a better growth-mode modification in the subsequent growth process. On one hand, the better c-axis orientation is inherited by the upper AlN epilayer, resulting in a lower screw dislocation density. On the other hand, the better growth-mode modification significantly suppresses edge dislocations by producing high-density nanoscale voids and many 90°bent dislocations. Therefore, the total threading dislocation density of the AlN film grown on the sputtered AlN buffer is dramatically reduced to an extremely low value of 4.7 × 10 7 cm −2 , which is 81.2% less than that of the AlN film grown on the MOCVD AlN buffer. This very simple yet effective technique demonstrates great potential for the massfabrication of low-cost and high-performance DUV devices.

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