A Simple Scheme for Photonic Generation of Microwave Waveforms Using a Dual-drive Mach–Zehnder Modulator

In this paper, a novel photonic scheme for the generation of square and triangular waveforms is proposed and experimentally demonstrated by using a dual-drive Mach–Zehnder modulator (DDMZM) without any optical signal processing. By properly setting the modulation index of the DDMZM, the square and triangular microwave waveforms could be easily achieved in conjunction with a 90° hybrid coupler. Furthermore, the modulation index of the DDMZM could be tuned for a low radio frequency (RF) signal power requirement by tuning the phase difference of the RF signals applied to the two arms of the DDMZM. The proposed scheme for the photonic generation of microwave waveforms is theoretically analyzed and experimentally demonstrated. The periodical triangular and square waveforms with repetition rates of 5 GHz, 8 GHz, and 10 GHz are successfully obtained. The root-mean-square errors between the generated and theoretical triangular and square waveforms with a repetition of 5 GHz are 0.042 and 0.053, respectively

Oxygen-vacancy and phosphorus-doping enriched NiMoO4 nanoarrays for high-energy supercapacitors

Exploring electrode materials with high effective surface and abundant active sites takes on a critical significance in achieving high-energy supercapacitors. Herein, the oxygen vacancies (Ov) and P-doping enriched NiMoO4 nanosheet arrays were synthesized through the combination of phosphorization and N2 plasma treatment. The combination strategy makes it possible to sharply increase and modulate the Ov content. The optimized P-NiMoO4-N2 is found with the highest Ov content, and the capacitive activity is well consistent with the increase in the Ov content among all samples. As revealed by experimental results, rich Ov increases the electrochemically accessible active-sites while enhancing the intrinsic conductivity. Thus, the optimized P-NiMoO4-N2 is enabled to reach a high capacity of 2180 F g−1 at a current density of 1 A g−1 and remains 83.9 % at 10 A g−1 with high cycling stability. After being assembled with activated carbon as the negative electrode, the asymmetric supercapacitor exhibits a high energy density of 56.8 Wh kg−1 at 0.75 kW kg−1 and maintains 41.6 Wh kg−1 at 15 kW kg−1. This work may create a novel path to enrich and adjust Ov in metal oxides for high-capacity and high-power supercapacitors. © 2022LTT20005; 21PJD018; National Natural Science Foundation of China, NSFC: 22075082; China Postdoctoral Science Foundation: 2020M681208; Science and Technology Commission of Shanghai Municipality, STCSM: 1852074440

Defects of CTLA-4 Are Associated with Regulatory T Cells in Myasthenia Gravis Implicated by Intravenous Immunoglobulin Therapy

Myasthenia gravis (MG) is a CD4+ T cell-dependent autoimmune disease resulting from aberrant immune response mediated by circulating autoantibodies at the neuromuscular junction. Intravenous immunoglobulin (IVIg) is an expensive and commonly used immunotherapeutic approach to treat patients with MG. The mechanisms of actions involved in IVIg treatment, however, remain to be investigated. In an effort to examine the roles of various subsets of CD4+ T cells in the periphery blood of MG and uncover the mechanisms that contribute to the therapeutical effects of IVIg, we first demonstrated that a subset of CD4+ T cells, CTLA-4-expressing regulatory T (Treg) cells, were underrepresented and functionally defective in MG patients. The dynamic profiling during the IVIg therapy course further revealed an inverse relationship between the frequency of CTLA-4+ Treg and the quantitative MG (QMG) score that represents disease severity. Our mechanistic studies indicated that IVIg expands CTLA-4-Treg cells via modulating antigen-presenting dendritic cells (DCs). To determine the molecular defects of CTLA-4 in abnormities of Treg in MG patients, we demonstrated hypermethylation at -658 and -793 CpGs of CTLA-4 promoter in MG Tregs. Interestingly, IVIg therapy significantly reduced the methylation level at these two sites in MG patients. Overall, our study may suggest a role of CTLA-4 in functionally defected Treg cells in MG and its actions involved in IVIg therapy

Tunable Head-Conducting Microwave-Absorbing Multifunctional Composites with Excellent Microwave Absorption, Thermal Conductivity and Mechanical Properties

Developing composite materials with both thermal conductivity and microwave absorption is an effective strategy to solve the problems of heat dissipation burden and microwave radiation interference caused by the development of miniaturization and high performance of portable electronic equipment. However, these properties are not easy to simultaneously implement due to the limitation of single type fillers with a single particle size, inspiring the possibility of realizing multifunctional composites with the introduction of composite fillers. In this work, using alumina (Al2O3) and zinc oxide (ZnO) as head-conducting fillers, carbonyl iron (Fe(CO)5) as microwave-absorbing fillers, silicone rubber (SR) composites (Al2O3/ZnO/Fe(CO)5/SR) with enhanced microwave absorption, high thermal conductivity and good mechanical properties were successfully mass prepared. It was found that the composites can achieve a thermal conductivity of 3.61 W·m−1·K−1, an effective microwave absorption bandwidth of 10.86–15.47 GHz. Especially, there is an effective microwave absorption efficiency of 99% at 12.46–14.27 GHz, which can realize the integration of electromagnetic shielding and heat dissipation. The compact microstructure, formed by the overlapping of large particle size fillers and the filling of their gaps by small particle size fillers, is helpful to enhance the thermal conduction path and weaken the microwave reflection. The heat-conducting microwave-absorbing Al2O3/ZnO/Fe(CO)5/SR composites also have the advantages of thermal stability, lightness and flexibility, providing a certain experimental basis for the research and development of high-performance and diversified composites

A label-free optical biosensor built on a low-cost polymer platform

Planar integrated optical biosensors are becoming more and more important as they facilitate label-free and real-time monitoring with high sensitivity. In this paper, the systematic work on the development of this kind of optical biosensor built on a novel polymer platform named PSQ-Ls will be presented. The material itself is of very low cost, and the optical devices with high performances are fabricated through a simple UV-based soft imprint lithography technique. Especially for ring resonator, Q value as high as 5 x 10(4) and 2.7 x 10(4) are achieved in air and water condition. These optical chips are functionalized efficiently with protein A molecules through physical immobilization, after careful investigation of the physicochemical and chemical properties of their surface. Both bulk sensing and surface sensing are performed. The proposed optical biosensor exhibits good response not only to its surrounding environment's change but also to the small amount of targeted molecules appearing in the buffered solution, which is human-IgG in our study

Organic silicone sol-gel polymer as a noncovalent carrier of receptor proteins for label-free optical biosensor application

Optical biosensing techniques have become of key importance for label-free monitoring of biomolecular interactions in the current proteomics era. Together with an increasing emphasis on high-throughput applications in functional proteomics and drug discovery, there has been demand for facile and generally applicable methods for the immobilization of a wide range of receptor proteins. Here, we developed a polymer platform for microring resonator biosensors, which allows the immobilization of receptor proteins on the surface of waveguide directly without any additional modification. A sol-gel process based on a mixture of three precursors was employed to prepare a liquid hybrid polysiloxane, which was photopatternable for the photocuring process and UV imprint. Waveguide films were prepared on silicon substrates by spin coating and characterized by atomic force microscopy for roughness, and protein adsorption. The results showed that the surface of the polymer film was smooth (rms = 0.658 nm), and exhibited a moderate hydrophobicity with the water contact angle of 97 degrees. Such a hydrophobic extent could provide a necessary binding strength for stable immobilization of proteins on the material surface in various sensing conditions. Biological activity of the immobilized Staphylococcal protein A and its corresponding biosensing performance were demonstrated by its specific recognition of human Immunoglobulin G. This study showed the potential of preparing dense, homogeneous, specific, and stable biosensing surfaces by immobilizing receptor proteins on polymer-based optical devices through the direct physical adsorption method. We expect that such polymer waveguide could be of special interest in developing low-cost and robust optical biosensing platform for multidimensional arrays