Satellite communication is moving toward multi-band, large bandwidth communication and high data rate space networking, which requires more processing, switching, and high-speed transmission ...capability of satellite communication payload. The electronic bottleneck of traditional microwave systems in processing speed and transmission bandwidth makes it difficult to adapt to the future demands of satellite communications. Aiming at the limitations of satellite communication based on traditional microwave technology, this article discusses the potential benefits of satellite communication payload based on microwave photonic (SCP-MP) to space information communication networks (SICN). Then it proposes the architecture of SCP-MP, along with its main components and functional structure. We also review the key technologies, such as low spurious frequency conversion, channelization, optical switching, chip, and integration, and discuss challenges. An outlook on the prospects of SCP-MP is also included.
Satellite communications face difficulties such as intensified environmental attenuation, dynamic time-varying links, and diverse business scenarios, which usually require channel coding schemes with ...high coding gain and high throughput. Low-density parity-check (LDPC) codes are dominant in satellite communication coding schemes due to their excellent performance in approaching the Shannon limit and the characteristics of parallel computing. The traditional weighted-Algorithm B decoding algorithm ignores the channel received information and involves frequent multiplication operations and iteration, which introduces the channel received information for hard-decision and constellation mapping processing. Meanwhile, we design the correlated reliability between the extrinsic information and the mapping processing information to improve the correctness of decoding. The multiplication operation in the iterative process can be replaced by the simple sum of the Hamming distance coefficient, the correlated reliability between the extrinsic information and the mapping processing information, and the extrinsic information frequency, thereby reducing the complexity and storage load of the system. The simulation results show that the presented MRAI-LDPC algorithm can obtain about 0.4 dB performance gain, and the average number of iterations is reduced by 68% under a low SNR. The algorithm can achieve better error-correcting performance and higher throughput, providing strong support for reliable transmission of satellite communications.
Inorganic-organic hybrid materials, especially metal-organic frameworks (MOFs) composed of metals and organic linkers, have emerged as a new class of versatile materials owing to their tunable ...structure and controllable functionality. As typical biocompatible MOFs, cyclic oligosaccharide cyclodextrin-based carbohydrate metal-organic frameworks (CD-MOFs) have recently attracted considerable attention due to their edible, renewable and biodegradable nature. Herein, we focus on the latest advances concerning these materials. First, the synthesis methods and structural diversity of CD-MOFs are introduced and summarized. Besides, the synthetic strategies of moisture-resistant CD-MOFs are also emphasized. Moreover, their applications, including gas adsorption, separation, sensing, memristor fabrication, as templates in nanoparticle synthesis, light emission and especially drug delivery, are systematically discussed and highlighted. Finally, to conclude the review, some insights and current challenges that need to be addressed for the further development of these materials are proposed. We anticipate that this review will result in a better understanding of CD-MOFs and will help maximize the potential functions of these materials.
This review takes an overview of the synthetic strategies, structural diversity and emerging bio-related applications of cyclodextrin-based metal-organic frameworks (CD-MOFs).
Low-grade gliomas (LGG) are commonly seen in clinical practice, and the prognosis is often poor. Therefore, the determination of immune-related risk scores and immune-related targets for predicting ...prognoses in patients with LGG is crucial. A single-sample gene set enrichment analysis (ssGSEA) was performed on 22 immune gene sets to calculate immune-based prognostic scores. The prognostic value of the 22 immune cells for predicting overall survival (OS) was assessed using the least absolute shrinkage and selection operator (LASSO) and univariate and multivariate Cox analyses. Subsequently, we constructed a validated effector T-cell risk score (TCRS) to identify the immune subtypes and inflammatory immune features of LGG patients. We divided an LGG patient into a high-risk-score group and a low-risk-score group based on the optimal cutoff value. Kaplan-Meier survival curve showed that patients in the low-risk-score group had higher OS. We then identified the differentially expressed genes (DEGs) between the high-risk-score group and low-risk-score group and obtained 799 upregulated genes and 348 downregulated genes. The analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) show that DEGs were mainly concentrated in immune-related processes. In order to further explore the immune-related genes related to prognosis, we constructed a protein-protein interaction (PPI) network using Cytoscape and then identified the 50 most crucial genes. Subsequently, nine DEGs were found to be significantly associated with OS based on univariate and multivariate Cox analyses. It was further confirmed that CD2, SPN, IL18, PTPRC, GZMA, and TLR7 were independent prognostic factors for LGG through batch survival analysis and a nomogram prediction model. In addition, we used an RT-qPCR assay to validate the bioinformatics results. The results showed that CD2, SPN, IL18, PTPRC, GZMA, and TLR7 were highly expressed in LGG. Our study can provide a reference value for the prediction of prognosis in LGG patients and may help in the clinical development of effective therapeutic agents.
The terahertz frequency band has the advantages of having a large bandwidth, narrow beam, strong penetration, and high security, and is an important direction for the frequency expansion of ...next-generation satellite communications. Due to the narrow terahertz beam, the pointing error caused by satellite perturbation will affect the attenuation of the terahertz wave power, resulting in a decrease in the received power of the system and affecting the communication performance of the system. In order to accurately analyze the influence of pointing error caused by satellite perturbation on the performance of space terahertz communication system, based on satellite perturbation model and Gaussian channel model, this paper deduces the accurate analysis of signal power attenuation model without pointing error and with pointing error untie. The antenna pointing error in the real environment is simulated by using the TLE data of the actual satellite, and the influence of the pointing error on the space terahertz communication is analyzed. The results show that the antenna pointing error caused by satellite perturbation changes periodically with the operation of the satellite, which will cause great signal power attenuation, reduce the signal-to-noise ratio of the space terahertz communication system, and seriously affect the communication quality. In addition, the higher the frequency, the greater the impact on space terahertz communication, which needs to be solved through attitude control and antenna compensation.
Offloading traffic from terrestrial areas to low-orbit satellite networks, the ultra-long-distance and ultra-large-range connectivity can be achieved by on-board routing and transmission. This paper ...investigates the relay-assisted NOMA-enabled uplink traffic offloading in the integrated satellite-terrestrial network. The joint energy efficiency maximum problem is formulated and then decomposed into two subproblems, i.e., the decoding sequence and power allocation (DS-PA) problem, and the users-satellites-subchannels association and transmit power allocation (USSA-TPA) problem. For DS-PA problem, the decoding sequence constraint is removed, and then the successive convex approximation method is utilized to solve it. To tackle the USSA-TPA issue, we reformulate it into two subproblems and resort to the alternate iteration method to deal with them iteratively. The numerical results show that the proposed joint optimization of energy efficiency for uplink traffic offloading cooperated with NOMA scheme outperforms other methods and their combinations. The performance of proposed USSA scheme and power allocation method is also discussed.
Channel modeling is crucial for inter-satellite terahertz communication system design. The conventional method involves manually constructing a mathematical channel model, which is labor-intensive, ...and using a neural network directly as a channel model lacks interpretability. This paper introduces a channel modeling approach based on symbolic regression. It is the first time that using transformer neural networks as the implementation tool of symbolic regression to generate the mathematical channel model from the channel data directly. It can save manpower and avoid the interpretability issue of using neural networks as a channel model. The feasibility of the proposed method is verified by generating a free space path loss model from simulation data in the terahertz frequency band.
Upgrading ethanol to higher order alcohols is desired but difficult using current biotechnological methods. In this study, we designed a completely artificial reaction pathway for upgrading ethanol ...to acetoin, 2,3-butanediol, and 2-butanol in a cell-free bio-system composed of ethanol dehydrogenase, formolase, 2,3-butanediol dehydrogenase, diol dehydratase, and NADH oxidase. Under optimized conditions, acetoin, 2,3-butanediol, and 2-butanol were produced at 88.78%, 88.28%, and 27.25% of the theoretical yield from 100 mM ethanol, respectively. These results demonstrate that this artificial synthetic pathway is an environmentally-friendly novel approach for upgrading bio-ethanol to acetoin, 2,3-butanediol, and 2-butanol.
Purpose
To investigate the mechanism of enhancing solubility and bioavailability of water-insoluble drug, valsartan (VAL), with being mega-loaded by cyclodextrin metal organic framework (CD-MOF).
...Methods
VAL was successfully mega-loaded into CD-MOF by magnetic agitation of VAL in ethanolic solution. Characterizations including powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), synchrotron radiation-based Fourier transform-infrared spectroscopy (SR-FTIR)
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C solid-state nuclear magnetic resonance spectroscopy (
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C SS-NMR), nitrogen gas adsorption, and small-angle X-ray scattering (SAXS) were carried out to confirm the mechanism and incorporation behavior of VAL in CD-MOF. Ball milling process combined with molecular modeling was also used to confirm the mechanism. Improvement of bioavailability in vivo was confirmed by pharmacokinetic experiment in beagles.
Results
As a carrier with payload 150% higher than conventional CD complexation, CD-MOF included molecules of VAL as complexations in the chambers of (γ-CD)
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, and nanoclusters in the confined spherical cages of (γ-CD)
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confirmed by SAXS and
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C SS-NMR. Ball milling combined with molecular modeling inferred that the reduced release rate of the milled CD-MOF with ultrahigh drug payload was mainly due to the partial aggregation of the VAL nanoclusters. The molecules of VAL as nanoclusters in the cages of (γ-CD)
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are critical in dramatically improving the apparent solubility (39.5-fold) and oral bioavailability (1.9-fold) of VAL in contrast to γ-CD inclusion.
Conclusions
The new understanding of drug nanoclusters in CD-MOF will help to design more efficient drug delivery systems using CD-MOF carrier with nanocavities.
In recent years, as giant satellite constellations grow rapidly worldwide, the co-existence between constellations has been widely concerned. In this paper, we overview the co-frequency interference ...(CFI) among the giant non-geostationary orbit (NGSO) constellations. Specifically, we first summarize the CFI scenario and evaluation index among different NGSO constellations. Based on statistics about NGSO constellation plans, we analyse the challenges in mitigation and analysis of CFI. Next, the CFI calculation methods and research progress are systematically sorted out from the aspects of interference risk analysis framework, numerical calculation and link construction. Then, the feasibility of interference mitigation technologies based on space, frequency domain isolation, power control, and interference alignment mitigation in the NGSO mega-constellation CFI scenario are further sorted out. Finally, we present promising directions for future research in CFI analysis and CFI avoidance.
