Low Complexity Hybrid Precoding in Millimeter Wave Massive MIMO Systems

Tongtong Cheng,Yigang He,Yuting Wu,Shuguang Ning,Yongbo Sui,Yuan Huang 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.4

As a preprocessing operation of transmitter antennas, the hybrid precoding is restricted by the limited computing resources of the transmitter. Therefore, this paper proposes a novel hybrid precoding that guarantees the communication efficiency with low complexity and a fast computational speed. First, the analog and digital precoding matrix is derived from the maximum eigenvectors of the channel matrix in the sub-connected architecture to maximize the communication rate. Second, the extended power iteration (EPI) is utilized to obtain the maximum eigenvalues and their eigenvectors of the channel matrix, which reduces the computational complexity caused by the singular value decomposition (SVD). Third, the Aitken acceleration method is utilized to further improve the convergence rate of the EPI algorithm. Finally, the hybrid precoding based on the EPI method and the Aitken acceleration algorithm is evaluated in millimeter-wave (mmWave) massive multiple-input and multiple-output (MIMO) systems. The experimental results show that the proposed method can reduce the computational complexity with the high performance in mmWave massive MIMO systems. The method has the wide application prospect in future wireless communication systems.

Heterologous expression of ZmNF-YA12 confers tolerance to drought and salt stress in Arabidopsis

Zhang Tongtong,Zheng Dengyu,Zhang Chun,Wu Zhongyi,Yu Rong,Zhang Zhongbao 한국식물생명공학회 2022 Plant biotechnology reports Vol.16 No.4

Drought and salinity are serious environmental factors limiting the growth and productivity of plants worldwide. Therefore, it is necessary to develop ways to improve drought and salinity stress tolerance in plants. In this study, a drought-responsive nuclear factor Y subunit A gene, ZmNF-YA12, was cloned from maize. qPCR revealed ZmNF-YA12 transcript in all vegeta- tive and reproductive tissues, with higher levels in young roots. Expression analyses of maize revealed that ZmNF-YA12 was induced by abscisic acid (ABA), jasmonic acid (JA), and abiotic stresses, including dehydration, high salinity, cold, and polyethylene glycol (PEG) treatment. The heterologous expression of ZmNF-YA12 in Arabidopsis plants resulted in increased root length and better plant growth than in wild-type (WT) plants under conditions of mannitol, salt, and JA stress on 1/2 MS medium. Transgenic Arabidopsis showed improved tolerance to drought and salt stresses in soil, and higher proline content and lower malondialdehyde (MDA) content than WT controls. The transgenic plants also maintained higher peroxidase (POD) activities than WT plants under conditions of NaCl stress. A yeast two-hybrid experiment demonstrated that ZmNF-YA12 interacted with ZmNF-YC1 and ZmNF-YC15. Moreover, the transcript levels of stress-responsive genes (RD29A, RD29B, RAB18, and RD22) were markedly increased in transgenic lines under conditions of drought and salt stress. These observa- tions suggested that the ZmNF-YA12 gene may confers drought and salt stress tolerance by regulating stress-related genes or interacting with ZmNF-YC1 and ZmNF-YC15, and has potential applications in molecular breeding with maintenance of production under conditions of stress.

Hepatocellular carcinoma prediction model performance decreases with long-term antiviral therapy in chronic hepatitis B patients

Xiaoning Wu,Xiaoqian Xu,Jialing Zhou,Yameng Sun,Huiguo Ding,Wen Xie,Guofeng Chen,Anlin Ma,Hongxin Piao,Bingqiong Wang,Shuyan Chen,Tongtong Meng,Xiaojuan Ou,Hwai-I Yang,Jidong Jia,Yuanyuan Kong,Hong Yo 대한간학회 2023 Clinical and Molecular Hepatology(대한간학회지) Vol.29 No.3

Background/Aims: Existing hepatocellular carcinoma (HCC) prediction models are derived mainly from pretreatment or early on-treatment parameters. We reassessed the dynamic changes in the performance of 17 HCC models in patients with chronic hepatitis B (CHB) during long-term antiviral therapy (AVT). Methods: Among 987 CHB patients administered long-term entecavir therapy, 660 patients had 8 years of follow-up data. Model scores were calculated using on-treatment values at 2.5, 3, 3.5, 4, 4.5, and 5 years of AVT to predict threeyear HCC occurrence. Model performance was assessed with the area under the receiver operating curve (AUROC). The original model cutoffs to distinguish different levels of HCC risk were evaluated by the log-rank test. Results: The AUROCs of the 17 HCC models varied from 0.51 to 0.78 when using on-treatment scores from years 2.5 to 5. Models with a cirrhosis variable showed numerically higher AUROCs (pooled at 0.65–0.73 for treated, untreated, or mixed treatment models) than models without (treated or mixed models: 0.61–0.68; untreated models: 0.51–0.59). Stratification into low, intermediate, and high-risk levels using the original cutoff values could no longer reflect the true HCC incidence using scores after 3.5 years of AVT for models without cirrhosis and after 4 years of AVT for models with cirrhosis. Conclusions: The performance of existing HCC prediction models, especially models without the cirrhosis variable, decreased in CHB patients on long-term AVT. The optimization of existing models or the development of novel models for better HCC prediction during long-term AVT is warranted.

Effect of naphthalene quinoline and H2S on DBT hydrodesulfurization over unsupported NiMoW catalyst

Changlong Yin,Haonan Zhang,Tongtong Wu,Zhuyan Wu,Kunpeng Li,Yan Kong,Chengwu Dong,Chenguang Liu 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.12

Unsupported catalysts have attracted much attention for high activity in comparison with the traditional supported catalyst. Meanwhile, the clear structure of unsupported catalysts is helpful for the recognition of active phase for conducting the industry production. The NiMoW unsupported catalyst was prepared by hydrothermal synthesis and characterized by BET, XRD and HRTEM. The effects of naphthalene, quinoline and H2S on the hydrodesulfurization reactivity of dibenzothiophene (DBT) were investigated in both a batch autoclave and a continuous 10 ml fixed bed micro-reactor over NiMoW and supported catalyst for comparison. The results showed that the hydrogenation reaction and the hydrogenolysis reaction occurred on different active sites. For supported catalyst, the inhibition was relatively weaker, and the inhibition of the hydrodesulfurization pathway was much higher than the direct desulfurization pathway. Although unsupported catalyst was very sensitive to quinoline and H2S in this experiment, the HDS ratio on the unsupported catalyst was maintained at a high level above 99.7%, which is attributed to the very high active site density of unsupported catalysts.

Occurrence, evolution, and functions of DNA phosphorothioate epigenetics in bacteria

Tong, Tong,Chen, Si,Wang, Lianrong,Tang, You,Ryu, Jae Yong,Jiang, Susu,Wu, Xiaolin,Chen, Chao,Luo, Jie,Deng, Zixin,Li, Zhiqiang,Lee, Sang Yup,Chen, Shi National Academy of Sciences 2018 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.115 No.13

<P><B>Significance</B></P><P>Phosphorothioate (PT) modification of the DNA sugar-phosphate backbone is an important microbial epigenetic modification governed by DndABCDE, which together with DndFGH, constitutes a restriction-modification system. We show that up to 45% of 1,349 identified bacterial <I>dnd</I> systems exhibit the form of solitary <I>dndABCDE</I> without the restriction counterparts of <I>dndFGH</I>. The combination of epigenomics, transcriptome analysis, and metabolomics suggests that in addition to providing a genetic barrier against invasive DNA, PT modification is a versatile player involved in the epigenetic control of gene expression and the maintenance of cellular redox homeostasis. This finding provides evolutionary and functional insights into this unusual epigenetic modification. Our results imply that PT systems might evolve similar to other epigenetic modification systems with multiple cellular functions.</P><P>The chemical diversity of physiological DNA modifications has expanded with the identification of phosphorothioate (PT) modification in which the nonbridging oxygen in the sugar-phosphate backbone of DNA is replaced by sulfur. Together with DndFGH as cognate restriction enzymes, DNA PT modification, which is catalyzed by the DndABCDE proteins, functions as a bacterial restriction-modification (R-M) system that protects cells against invading foreign DNA. However, the occurrence of <I>dnd</I> systems across a large number of bacterial genomes and their functions other than R-M are poorly understood. Here, a genomic survey revealed the prevalence of bacterial <I>dnd</I> systems: 1,349 bacterial <I>dnd</I> systems were observed to occur sporadically across diverse phylogenetic groups, and nearly half of these occur in the form of a solitary <I>dndBCDE</I> gene cluster that lacks the <I>dndFGH</I> restriction counterparts. A phylogenetic analysis of 734 complete PT R-M pairs revealed the coevolution of M and R components, despite the observation that several PT R-M pairs appeared to be assembled from M and R parts acquired from distantly related organisms. Concurrent epigenomic analysis, transcriptome analysis, and metabolome characterization showed that a solitary PT modification contributed to the overall cellular redox state, the loss of which perturbed the cellular redox balance and induced <I>Pseudomonas fluorescens</I> to reconfigure its metabolism to fend off oxidative stress. An in vitro transcriptional assay revealed altered transcriptional efficiency in the presence of PT DNA modification, implicating its function in epigenetic regulation. These data suggest the versatility of PT in addition to its involvement in R-M protection.</P>