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Dynamically monitoring intracellular glutathione (GSH), a crucial biomarker of oxidative stress, is of significance for the diagnosis and treatment of certain diseases. Although manganese dioxide (MnO2) based GSH fluorescent sensors have exhibited high sensitivity and good selectivity owing to the specific reactivity between GSH and MnO2, near-infrared (NIR) MnO2 based nanoprobes for GSH detection are scarce. Herein, we have developed a NIR activatable fluorescence nanoprobe for the imaging and determination of intracellular GSH based on a core–shell nanoparticle, consisting of NIR emitted gold nanocluster doped silica as the fluorescent core and manganese dioxide as the GSH-responsive shell (named AuNCs@MnO2). Due to the absorption competition mechanism, the outer MnO2 shell rather than the inner AuNCs core preferentially absorbed the excitation light, thus leading to fluorescence quenching of the inner AuNCs core. Upon addition of GSH, the fluorescence of the nanoprobe restored along with the reduction of MnO2 to Mn2+ because of the absorption competition disappearance-induced emission. The activatable fluorescence linearly increased upon changing the GSH concentration in the range of 2 to 5000 μM with a detection limit of 0.67 μM. The cytotoxicity test shows that the AuNCs@MnO2 nanoprobes have a good biocompatibility. After entering the cancer cells, the intracellular GSH degraded the outermost MnO2 shell and initiated the NIR fluorescence restoration of AuNCs, which can be used to monitor the dynamic change of intracellular GSH. This strategy provides an NIR-activatable way to detect GSH levels in living cells and offers a promising platform for the diagnosis and treatment of GSH-related diseases. [ABSTRACT FROM AUTHOR]

A stretchable microwave metamaterial absorber with specific pattern design is proposed and fabricated in this paper to improve the stability of microwave absorption for deformation. Compensation mechanism is revealed by the electrical current loop for resonance absorption excitation in an equivalent circuit model. The proposed metamaterial absorber with a slotted cross pattern is compared with the conventional cross pattern absorber. A stretchable silver conductive ink validates the silk screen printing of resistive patterns on flexible polydimethylsiloxane substrate and hence realizes the stretching experiments. In a 25% stretch, the resonant frequency of the compensated absorber shifts only 0.5% for TM polarization, comparing to the 8% shifting of the conventional structure. [ABSTRACT FROM AUTHOR]

Microwave absorbing honeycomb composites with grading coating thickness are prepared by impregnation of aramid paper frame within water solutions of conductive carbon blacks. Based on effective medium method, grading impedance in the composites can be theoretically expressed by a linear approximation of the inversely tapered effective permittivity at wave propagation direction, which provides a feasible way to optimize the design of microwave absorbing honeycomb structures. The consistent result of calculations and experimental measurements for positive impedance grading design confirms the broadband absorption effect in high frequencies. [ABSTRACT FROM PUBLISHER]

Amorphous Fe79Si16B5 metallic microwires have been prepared by a melt extract method. Magnetic hysteresis measurements show that the microwires exhibit a strongly magnetic anisotropy. The dependences of permeability and permittivity of microwires on frequency have been studied by the Kittel law and the multiple Lorentzian dispersion law, respectively. Single layer absorber filled with the microwires has a good microwave absorption performance when its thickness is larger than 4 mm. However, the absorption band is found narrow on a 2-dimensional contour map. [ABSTRACT FROM AUTHOR]

In hyperspectral remote sensing detection, existing camouflage technology is far behind detection technology, causing a mortal threat to the survival of military targets on the battlefield. In this study, Palygorskite is selected as an innovative water absorption simulation material, combined with Cr 2 O 3 and polyurethane (PU) to form a camouflage coating simulating the reflectivity spectrum of green vegetation to counter hyperspectral imaging technology. Water absorption peaks reflectivity of purified Palygorskite reaches 55.4% and 39.1% under ultrasonic dispersion for 30 min in 3 wt% (NaPO 3) 6 , demonstrating good reflection characteristics. The best camouflage coating is obtained with 1 g Cr 2 O 3 , 5 g Palygorskite, and PU varnish by a coating method, demonstrating a good spectral similarity coefficient of 0.9124 and a cosine value of 0.9316. The excellent simulation effect is attributed to the synergistic effect of the Palygorskite crystal structure and spectral terms splitting of Cr3+ in Cr 2 O 3. The reflectivity spectrum of coating meets USA military specifications for an ultralightweight camouflage net system, demonstrating the great potential of Palygorskite in this field. [ABSTRACT FROM AUTHOR]

Generally speaking, thermal stability is the key factor for microwave absorbers (MAs) at high temperature. In this paper, we first propose to apply a novel material called Cr 2 AlC (CAC) in the high temperature field. The self-made high purity CAC powder prepared by salt bath exhibits good microwave absorption performance and outstanding. Thermogravimetric (TG) analysis indicates the CAC begins to oxidize significantly above 800 °C. Moreover, the effective medium theory is adopted to calculate the microwave absorption performance for the CAC/paraffin composite material. We found that the sample with 70 wt% CAC (CAC70) has a minimum reflection loss of −25.09 dB at 11.08 GHz and its effective absorption bandwidth (below −10 dB) is 2.2 GHz (10.2–12.4 GHz) at the thickness of 2.00 mm, which indicates a thin layer of Al 2 O 3 at room temperature will not affect the entry of electromagnetic waves and internal electrical losses. The high anti-oxidation layered structure CAC provides an opportunity to expand microwave absorption in high temperature applications. • The most probable kinetic mechanism function of Cr 2 AlC solid-state oxidation was calculated by FWO method. • The minimum reflection loss at 2 mm is -25.09 dB. Effective absorption bandwidth reaches 2.2 GHz in the X band. • We proposed protential application in the field of high-temperature wave absorption. [ABSTRACT FROM AUTHOR]