A Novel Non-Coherent Q-Ary TH-PPM Transceiver.

Time-hopping pulse position modulation (TH-PPM) stands out as a secure communication due to the pseudo-random characteristics of its time-hopping sequence. However, the conventional TH-PPM transceiver encounters challenges in implementation, particularly in achieving the requisite high precision for synchronization. This paper introduces a novel non-coherent Q-ary TH-PPM transceiver, designed to surpass the Bit error rate (BER) performance of conventional TH-PPM transceivers in scenarios under non-ideal synchronization conditions, which also being straightforward to implement. Firstly, we provide an overview of the conventional TH-PPM transceiver. Secondly, the novel TH-PPM transceiver is introduced. In this context, a novel method for generating the TH-PPM signal is proposed for the transmitter, and a parallel matched-filter algorithm, adapted to the new TH-PPM signal, is presented for the receiver. Subsequently, the investigation delves into an in-depth analysis of BER performance, considering both ideal synchronization conditions and non-ideal synchronization conditions, for both the conventional and the new TH-PPM transceiver. Furthermore, the paper proposes a numerical simulation to validate the theoretical findings. The results demonstrate that the new TH-PPM transceiver outperforms the conventional counterpart by showing better BER performance in scenarios with non-ideal synchronization conditions.

Covert Information Mapped Spatial and Directional Modulation toward Secure Wireless Transmission.

Recently, the concept of spatial and direction modulation (SDM) has been developed to reap the advantages of both spatial modulation (SM) and directional modulation (DM). On the one hand, DM ensures the transmission security at the expected direction. On the other hand, the structure of SM-aided distributed receivers can enhance the security even if the eavesdropper is located in the same direction as the legitimate receiver. However, the above advantages are achieved based on the assumption that the eavesdropper is not equipped with distributed receivers. On the other hand, the information security can no longer be guaranteed when the eavesdropper is also equipped with distributed receivers. To alleviate this problem, we considered a joint design of SDM and covert information mapping (CIM) in order to conceive of a more robust structure of CIM-SDM. Furthermore, both the detection performances at the eavesdropper and the legitimate user were quantified through theoretical derivation. In general, both the analysis and simulation results supported that the proposed CIM-SDM structure provides more robust secure performance compared to the original SDM, even if the extreme condition of distributed receivers at the eavesdropper is considered, at the cost of moderate performance loss at the legitimate user.

BER Performance Analysis of Non-Coherent Q-Ary Pulse Position Modulation Receivers on AWGN Channel.

This paper introduces the structure of a Q-ary pulse position modulation (PPM) signal and presents a noncoherent suboptimal receiver and a noncoherent optimal receiver. Aiming at addressing the lack of an accurate theoretical formula of the bit error rate (BER) of a Q-ary PPM receiver in the additive white Gaussian noise (AWGN) channel in the existing literature, the theoretical formulas of the BER of a noncoherent suboptimal receiver and noncoherent optimal receiver are derived, respectively. The simulation results verify the correctness of the theoretical formulas. The theoretical formulas can be applied to a Q-ary PPM system including binary PPM. In addition, the analysis shows that the larger the Q, the better the error performance of the receiver and that the error performance of the optimal receiver is about 2 dB better than that of the suboptimal receiver. The relationship between the threshold coefficient of the suboptimal receiver and the error performance is also given.

ABT-737 sensitizes curcumin-induced anti-melanoma cell activity through facilitating mPTP death pathway.

In the current study, we studied the potential role of ABT-737, a novel Bcl-2 inhibitor, on curcumin-induced anti-melanoma cell activity in vitro. The associated mechanisms were also investigated. We demonstrated that ABT-737 significantly sensitized curcumin-induced activity against melanoma cells (WM-115 and B16 lines), resulting in substantial cell death and apoptosis with co-administration. At the molecular level, curcumin and ABT-737 synergistically induced mitochondrial permeability transition pore (mPTP) opening in melanoma cells, the latter was evidenced by mitochondrial membrane potential (MPP) reduction and mitochondrial complexation between cyclophilin-D (CyPD) and adenine nucleotide translocator 1 (ANT-1). Significantly, mPTP blockers, including cyclosporin A and sanglifehrin A, remarkably inhibited curcumin and ABT-737 co-administration-induced cytotoxicity against melanoma cells. Meanwhile, siRNA-mediated knockdown of CyPD or ANT-1, the two key components of mPTP, alleviated WM-116 cell death by the co-treatment. Collectively, we show that ABT-737 sensitizes curcumin-induced anti-melanoma cell activity probably through facilitating mPTP death pathway. ABT-737 could be further investigated as a potential curcumin adjuvant in melanoma and other cancer treatment.

Combining quasi-ZIF-67 hybrid nanozyme and G-quadruplex/hemin DNAzyme for highly sensitive electrochemical sensing.

Zeolitic imidazolate frameworks (ZIFs), a famous subfamily of metal-organic frameworks (MOFs), are considered promising electrocatalysts. Herein, ZIF-67 was selected as an electrocatalyst for designing electrochemical sensors due to having the best electrocatalytic activity in ZIFs. To overcome the insufficient electrocatalytic activity of ZIFs, ZIF-67 derivatives (QZIF-67-X, where X represents calcination time) were obtained by calcining at 250 °C for a certain time. The porous structure of the precursor in QZIF-67-X is maintained, exposing more active centers. QZIF-67-X could accelerate electron transfer and lead to improve the electrocatalytic performance. Moreover, QZIF-67-2 was chosen as an Au nanoparticle-supported nanocarrier to further bind G-quadruplex/hemin DNAzymes with strong catalytic activity due to the best supporting activity of QZIF-67-2 among QZIF-67-X. The synergistic catalysis of QZIF-67-2 and G-quadruplex/hemin DNAzymes effectively amplified the reduction current signal of H2O2. The linear range of the prepared electrochemical sensor was 2 µM-65 mM, and the detection limit was 1.2 µM. Moreover, the real-time detection of H2O2 from HepG2 cells was achieved by the sensor, providing a novel technique for efficient anticancer drug evaluation. These results suggested that QZIF-67 can be utilized as an efficient electrocatalyst for improving the sensitivity of sensors.

Direct Electrodeposition of Bimetallic Nanostructures on Co-Based MOFs for Electrochemical Sensing of Hydrogen Peroxide.

Hydrogen peroxide (H2O2) is the most significant reactive oxygen species in biological systems. Here, we reported an electrochemical sensor for the detection of H2O2 on the basis of bimetallic gold-platinum nanoparticles (Au3Pt7 NPs) supported by Co-based metal organic frameworks (Co-MOFs). First, Au3Pt7 NPs, with optimal electrocatalytic activity and accessible active surface, can be deposited on the surface of the Co-MOF-modified glassy carbon electrodes (Au3Pt7/Co-MOFs/GCE) by one-step electrodeposition method. Then, the electrochemical results demonstrated that the two-dimensional (2D) Co-MOF nanosheets as the supporting material displayed better electrocatalytic properties than the 3D Co-MOF crystals for reduction of H2O2. The fabricated Au3Pt7/2D Co-MOF exhibited high electrocatalytic activity, and the catalytic current was linear with H2O2 concentration from 0.1 µM to 5 mM, and 5-60 mM with a low detection limit of 0.02 µM (S/N = 3). The remarkable electroanalytical performance of Au3Pt7/2D Co-MOF can be attributed to the synergistic effect of the high dispersion of the Au3Pt7 NPs with the marvelous electrochemical properties and the 2D Co-MOF with high-specific surface areas. Furthermore, this sensor has been utilized to detect H2O2 concentrations released from the human Hela cells. This work provides a new method for improving the performance of electrochemical sensors by choosing the proper support materials from diverse crystal morphology materials.