Subterranean rodents have evolved many features to adapt to their hypoxic environment. The brain is an organ that is particularly vulnerable to damage caused by exposure to hypoxic conditions. To investigate the mechanisms of adaption to a hypoxic underground environment, we carried out a cross-species brain transcriptome analysis by RNA sequencing and identified genes that are differentially expressed between the subterranean vole Lasiopodomys mandarinus and the closely related above-ground species Lasiopodomys brandtii under chronic hypoxia [10.0% oxygen (O₂)] and normoxia (20.9% O₂). A total of 355 million clean reads were obtained, including 69,611 unigenes in L. mandarinus and 69,360 in L. brandtii. A total of 235 and 92 differentially expressed genes (DEGs) were identified by comparing the hypoxic and control groups of L. mandarinus and L. brandtii, respectively. A Gene Ontology (GO) analysis showed that upregulated DEGs in both species had similar functions in response to hypoxia, whereas downregulated DEGs in L. mandarinus were enriched GO terms related to enzymes involved in aerobic reactions. In the Kyoto Encyclopedia of Genes and Genomes pathway analysis, upregulated DEGs in L. mandarinus were associated with angiogenesis and the increased O₂ transport capacity of red blood cells, whereas downregulated DEGs were associated with immune responses. On the other hand, upregulated DEGs in L. brandtii were associated with cell survival, vascular endothelial cell proliferation, and neuroprotection, while downregulated genes were related to the synaptic transmission by neurons. L. mandarinus actively adapts its physiological functions to hypoxic conditions, for instance by increasing O₂ transport capacity and modulating O₂ consumption. In contrast, L. brandtii reacts passively to hypoxia by decreasing overall activity in order to reduce O₂ consumption. These results provide insight into hypoxia adaptation mechanisms in subterranean rodents that may be applicable to humans living at high altitudes or operating in other O₂-poor environments.

Hybrid free space optical (FSO)/radio frequency (RF) system has attracted extensive attention because of its advantages of both the FSO and RF links. From the viewpoint of overall system performance, this paper presents a systematic analysis method of communication performance and security performance of the hybrid FSO/RF system with the Málaga turbulence channel and the $\alpha -\mu$ fading channel. The hybrid FSO/RF system adopts the diversity method of maximum ratio combining (MRC) to receive signals. The new expressions of communication performance parameters (i.e., the bit error rate, the outage probability, the ergodic channel capacity) of the only FSO system and the hybrid system are obtained. Then, the new expressions of the security performance parameters (i.e., the security outage probability and the strictly positive secrecy capacity) of the hybrid system with the FSO or RF links eavesdropping are derived, respectively. Our derived analytical expressions present an efficient tool to investigate the impact of system parameters on the overall performance of the hybrid system, namely modulation scheme, turbulence intensity, pointing errors, target rate, and eavesdropper output signal-to-noise ratio. The simulation results show that compared with the only FSO system, the hybrid system can significantly improve the communication performance of the system; the communication performance of the hybrid system using coherent binary phase shift keying (CBPSK) modulation is obviously better than the other two modulation technologies; with the deterioration of atmospheric environment (increasing turbulence intensity and pointing errors), the communication performance and security performance of the hybrid system will decline; both RF link eavesdropping and FSO link eavesdropping have a greater impact on the security performance of the hybrid systems; whether it is FSO link eavesdropping or RF link eavesdropping, the reduction of target rate and output signal-to-noise ratio of the eavesdropper can improve the security performance of the hybrid system.

The microbial synthesis of paclitaxel is attractive for its short-cycle, cost-effectiveness, and sustainability. However, low paclitaxel productivity, depleted capacity during subculture and storage, and unclear biosynthesis mechanisms restrain industrial microbial synthesis. Along with the isolation of various paclitaxel-producing microorganisms and the development of versatile molecular tools, tremendous promises for microbial paclitaxel synthesis have become increasingly prominent. In this review, we summarize the progress of microbial synthesis of paclitaxel in recent years, focusing on paclitaxel-producing endophytes and representative engineering microorganism hosts that were used as chassis for paclitaxel precursor synthesis. Numerous wide-type microbes can manufacture paclitaxel, and fermentation process optimization and strain improvement can greatly enhance the productivity. Engineered microbes can efficiently synthesize precursors of paclitaxel by introducing exogenous synthetic pathway. Mining paclitaxel synthetic pathways and genetic manipulation of endophytes will accelerate the construction of microbial cell factories, indefinitely contributing to paclitaxel mass production by microbes. This review emphasizes the potential and provides solutions for efficient microbial paclitaxel mass production.

Studies have shown that radiotherapy (RT) has powerful immune-stimulating effects. However, RT-mediated distal tumor regression is rare in clinical practice. Here, with an animal experimental model, we found that RT shaped an immunosuppressive landscape characterized by a high-influx of myeloid-derived suppressor cells (MDSCs), and the induction of immunologically silent tumor apoptosis, hindering the efficacy of radioimmunotherapy. To address this issue, we developed a spatiotemporally controlled nanomedicine for remodeling the immunosuppressive tumor microenvironment (TME) post-RT. Decitabine (DAC)-loaded ferritin (Ft) were crosslinked via an azobenzene linker, and meanwhile encapsulated with all-trans retinoic acid (ATRA) to construct a Ft@DAC@ATRA nanoassembly (denoted as FD@ATRA), which dissociated into monodispersive Ft@DAC units in hypoxia TME. The released ATRA could eliminate immunosuppressive MDSCs, and meanwhile Ft@DAC selectively induced immunogenic pyroptosis of the tumor by targeting the transferrin receptor 1 overexpressed on the tumor to effectively activate CD8⁺ T cells. FD@ATRA treatment reshaped the tumor immune landscape post-RT with an increase of 16.8% in tumor-infiltrating IFN-γ⁺CD8⁺ T cells. Moreover, FD@ATRA-enhanced RT remained effective in large, treatment-resistant tumors, and the inhibition rate of FD@ATRA-enhanced RT on distant tumors improved by 47% compared to the RT group alone, providing an effective therapeutic approach to improve the clinical outcomes of radioimmunotherapy.

Recently, an orthogonal frequency division multiplexing (OFDM) technique for the infinite impulse response (IIR) channel (IIR-OFDM) was proposed, which carries the dedicated guard interval to maintain the circular convolution of the received signal and channel coefficients. Therefore, the loop of an IIR channel can be converted to the frequency domain, and single-tap equalization can still be used to equalize loop interference, like classical OFDM. In this paper, we describe how to build the IIR system based on the channel with loops and derive the properties of the dedicated guard interval for a general multi-order IIR channel, which is different from the classical cyclic prefix (CP) obtained by replicating the samples at the tail end of the signal. In particular, we address two special models for first-order and delay IIR channels. It is demonstrated that the guard interval composition and power characteristics of the two special models are similar. Moreover, the complexity of the guard interval depends not only on the maximum delay of the loop, but also on the number of loops. Finally, we simulate the IIR-OFDM performance under different IIR channels.

Orthogonal frequency division multiplexing (OFDM) is widely used in broadband wireless communication systems because of its high spectral efficiency, flexible subcarrier allocation, and robustness against frequency-selective fading. However, the high peak-to-average power ratio (PAPR) of OFDM signals reduces the power efficiency of high-power amplifiers and may introduce nonlinear distortion. To address this problem, this paper proposes a multiplier-free Dual-Hadamard PAPR-reduction architecture. The term multiplier-free refers to the additional precoding and phase-weighting operations introduced by the proposed PAPR reduction module, excluding the common OFDM FFT/IFFT operations. Specifically, the proposed architecture combines fast Walsh–Hadamard transform (FWHT) precoding, interleaved partitioning (ILP), and Hadamard-based partial transmit sequence (H-PTS) weighting. Since the FWHT matrix and the H-PTS phase codebook contain only binary signs, the main additional operations are implemented by additions, subtractions, and sign inversions. Simulation results demonstrate that the proposed method reduces the PAPR relative to conventional OFDM without degrading the system’s bit error rate (BER) performance in an additive white Gaussian noise (AWGN) channel when the side information is recovered correctly.