2023年1月
pH and Nitrate Drive Bacterial Diversity in Oil Reservoirs at a Localized Geographic Scale
Ying Xu,Jianwei Wang, Qingjie Liu, Qun Zhang, Jiazhong Wu, Minghui Zhou, Yong Nie, and Xiao-Lei Wu
Abstract
Oil reservoirs are one of the most important deep subsurface biospheres. They are inhabited by diverse microorganisms including bacteria and archaea with diverse metabolic activities. Although recent studies have investigated the microbial communities in oil reservoirs at large geographic scales, it is still not clear how the microbial communities assemble, as the variation in the environment may be confounded with geographic distance. In this work, the microbial communities in oil reservoirs from the same oil field were identified at a localized geographic scale. We found that although the injected water contained diverse exogenous microorganisms, this had little effect on the microbial composition of the produced water. The Neutral Community Model analysis showed that both bacterial and archaeal communities are dispersal limited even at a localized scale. Further analysis showed that both pH and nitrate concentrations drive the assembly of bacterial communities, of which nitrate negatively correlated with bacterial alpha diversity and pH differences positively correlated with the dissimilarity of bacterial communities. In contrast, the physiochemical parameters had little effect on archaeal communities at the localized scale. Our results suggest that the assembly of microbial communities in oil reservoirs is scale- and taxonomy-dependent. Our work provides a comprehensive analysis of microbial communities in oil reservoirs at a localized geographic scale, which improves the understanding of the assembly of the microbial communities in oil reservoirs.
Source
MICROORGANISMS
Volume11Issue1
DOI10.3390/microorganisms11010151
2023年1月
Sedimentation of elliptical particles in Bingham fluids using graphics processing unit accelerated immersed boundary-lattice Boltzmann method
Da Hui ; Zhijing Xu; Guiyong Zhang; Moubin Liu
Abstract
Elliptical particles settling in Bingham fluids in a confined, the vertical channel is studied using the immersed boundary-lattice Boltzmann method to understand their sedimentation characteristics. The present elliptical particles-Bingham fluids two-phase systems involve a single particle, a pair of particles, a chain of particles, and a cluster of particles. The graphics processing unit (GPU) is used to improve computational efficiency. Special attention is placed on the influence of yield stress on sedimentation behavior. For a pair of elliptic particles, alongside the drafting-kissing-tumbling (DKT) mode or non-DKT sedimentation mode, a periodic sedimentation mode is found. The results indicate that two elliptic particles keep a kissing state and their trajectories and orientations periodically change during settling in the confined channel. For the elliptic particles chain, the first kissing occurs between the middle and lower particles regarding any Bingham number. Moreover, particles form the cluster for different inclination angles of the particle chain at the Bingham number Bn = 0.02. For the cluster of particles ( 15 x 15 ), the effect of vortex interaction around particles in Newtonian fluids is revealed, and the rheological property of the fluid-particle interaction in Bingham fluids is displayed. Overall, the role of yield stress on the sedimentation of elliptic particles is significant. With the acceleration of GPU, the present method has great potential for modeling large numbers of particles settling in non-Newtonian fluids.
Source
PHYSICS OF FLUIDS
Volume35Issue1
DOI10.1063/5.0133124
2023年1月
Briarane-type diterpenoids, the inhibitors of osteoclast formation by interrupting Keap1-Nrf2 interaction and activating Nrf2 pathway
Xinyi Qi, Xu Zhang, Junjun Meng, Jingshuai Wu, Wei Cheng, Jian Huang, Wenhan Lin
Abstract
Chemoinformatic and bioassay-guided fractionation of a gorgonian coral Junceella juncea resulted in the isolation of 45 briarane-type diterpenoids, of which 16 new analogues were characterized. Their structures were identified by extensive analyses of the spectroscopic data. Most isolated briaranes showed significant inhibition against the receptor activator of nuclear factor kappa B ligand (RANKL)-induced osteoclast differentiation in bone marrowderived macrophages cells (BMMs). Praelolide, one of the active analogues, significantly activates nuclear factor erythroid-2-related factor 2 (Nrf2) nucleus translocation, induces the expression of Nrf2-targeted genes, suppresses reactive oxygen species (ROS) production, abrogates the activation of downstream mitogen-activated protein kinase (MAPK)/nuclear factor-kappa B (NF kappa B) signaling, and subsequently attenuates osteoclast differentiation. Mechanically, praelolide interacts with Kelch-like ECH-associated protein 1 (Keap1) protein by noncovalent interaction to interrupt the interaction between Keap1 and Nrf2 and thereby to activate the Nrf2 signaling pathway. In addition, praelolide rescues the bone loss in prednisone-induced zebrafish. The present study provided praelolide as a new natural scaffold to remedy osteoclastogenic bone disease.
Source
EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY
Volume246
DOI10.1016/j.ejmech.2022.114948
2023年1月
顺变柱体式光纤微地震检波器研制及实验
董小卫; 谢斌; 刘飞; 丁雅洁; 张敏; 潘树林; 郭长永
Abstract
为满足油气勘探开发微地震监测的需求,基于非平衡迈克尔逊干涉仪设计了一种新型弹性顺变柱体式光纤加速度微地震检波器,建立了检波器特征参数力学分析理论模型。通过与标准压电式光纤加速度检波器进行室内振动模拟对比测试,该新型光纤检波器的灵敏度> 40 dB、谐振频率>1.2 kHz,实验测试数据与理论模型计算结果具有很好的吻合度,结合水力压裂射孔信号现场探测效果,表明所研制的光纤检波器在探测油气勘探开发弱震级、高频微地震信号方面具备可行性。
Source
《西安石油大学学报：自然科学版》 |2023年第1期|52-58|共7页
DOI:10.3969/j. issn. 1673-064X.2023.01.006
2023年2月
Response of Microbial Communities on Cathode with Different Potentials in a Single-Chamber Reactor
Liyun An, YingChun Yan, Yong Nie, Min Gou, YueQin Tang & Xiao-Lei Wu
Abstract
Microbes use both organic and inorganic compounds as electron donors, with different electronic potentials, to produce energy required for growth in environments. Conventional studies on the effects of different electron donors on microbial community has been extensively studied with a set cathode potential. However, it remains under-researched how a microbial community response to the different redox potentials in different environments. Here, we incubated a lake sediment in a single-chamber reactor equipped with three working electrodes, i.e., with potentials of - 0.29 V, - 0.05 V versus standard hydrogen electrode and open-circuit, respectively. Results reveal that the structure of bacterial communities was highly similar for all closed-circuit electrodes (- 0.29 V, - 0.05 V), while differing significantly from those on open-circuit electrodes. We also show that specific bacteria were preferentially enriched by different electrode potentials, i.e., Pseudomonas and Rhodobacter preferentially grew on - 0.05 V and - 0.29 V cathode potentials, Azospirillum and Bosea preferentially grew on - 0.05 V; while Ferrovibrio, Hydrogenophaga, Delftia, and Sphingobium preferentially grew on - 0.29 V. In addition, microorganisms selectively enriched on open-circuit electrodes possess higher connectivity and closer relationship than microorganisms selectively enriched on closed-circuit electrode.
Source
CURRENT MICROBIOLOGY
Volume80Issue2
DOI10.1007/s00284-022-03148-1
2023年2月
Spatial-Temporal Variability and Sources of Lead (Pb) in the Indian Ocean and Asian Marginal Seas
Qian, Na; Boyle, Edward A.; Zhou, Liping; Tanzil, Jani; Chen, Qinqin; Zhang, Shuo; Chen, Mengli
Abstract
Since North America and European countries phased out leaded gasoline, Asia has become the major contemporary lead (Pb) source to the marine environment, at first from leaded gasoline, but more recently from coal burning and other high-temperature industrial activities. Pb in the Indian Ocean remains relatively under-evaluated after & sim;2000 and is further complicated by various oceanic processes (e.g., monsoons, boundary exchange with particulates). Here, we present three annually resolved coral skeletal Pb isotope and concentration records from the central and eastern Indian Ocean (Salomon Atoll, 1989-2009; Diego Garcia Atoll, 1999-2009; and Phuket Island, 1945-2010), and synthesize published coral/sedimentary records to reconstruct the spatial-temporal variability of anthropogenic Pb around the region. Pb isotopes in all corals coherently fall along the mixing line between Asian aerosols and the natural crust. However, higher contributions of natural Pb are found in corals located in the coastal region than those in the open ocean, despite the greater contributions of anthropogenic Pb expected in coastal water near human emission sources. This geographical difference suggests that exchanges between dissolved Pb and natural particles at ocean boundaries significantly contribute to the Pb isotope compositions in regional seawater and are subsequently recorded in corals. The temporal variability of Pb concentrations in corals and sedimentary records signifies decreasing trends in Southeast Asia but increasing trends in South Asia. This study contributes new and timely Pb and Pb isotope data for the Indian Ocean and illustrates the importance of boundary exchange in marine Pb cycling.
Source
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
Volume128Issue2
DOI10.1029/2022JC019222
2023年2月
水下仿生侧线感知研究进展
翟宇凡, 熊明磊, 王晨, 谢广明
Abstract
侧线是鱼类针对水下环境特有的感知器官, 能够帮助鱼类感知周围水环境信息。受此启发, 设计研制人工侧线系统并应用于水下机器人, 已成为水下无人系统研究的热点之一, 受到国内外学者广泛关注。论文概述水下仿生侧线感知的相关研究进展, 从仿生原理、结构设计、感知功能等角度, 系统地介绍仿生侧线感知的国内外发展现状, 具体介绍了作者团队基于仿箱鲀机器鱼以及仿生侧线系统开展的运动状态估计、姿态保持控制、邻近感知等研究工作。通过对现有研究的分析与总结, 进一步提出了水下仿生侧线感知领域未来的发展方向: 传感器阵列设计优化、自然环境下的流场感知、避障行为与集群行为的实现等。
Source
水下无人系统学报, 2023, 31(1): 50-67
doi: 10.11993/j.issn.2096-3920.2022-0073
2023年3月
Chemical Investigation of Metabolites Produced by a Deep-Sea-Derived Fungus Penicillium sp.
Wenfang Zhang, Dong Liu, Zhenchang Wen, Wenhan Lin & Jing Xu
Source
CHEMISTRY OF NATURAL COMPOUNDS
Volume59Issue1Page193-196
DOI10.1007/s10600-023-03952-6
2023年4月
Bio-Active Products from Mangrove Ecosystems
Wenhan Lin1,Guoqiang Li, and Jing Xu
Source
MARINE DRUGS
Volume21Issue4
DOI10.3390/md21040239
2023年4月
Predicting microbial community compositions in wastewater treatment plants using artificial neural networks
Liu, Xiaonan; Nie, Yong; Wu, Xiao-Lei
Abstract
Background Activated sludge (AS) of wastewater treatment plants (WWTPs) is one of the world's largest artificial microbial ecosystems and the microbial community of the AS system is closely related to WWTPs' performance. However, how to predict its community structure is still unclear.
Results Here, we used artificial neural networks (ANN) to predict the microbial compositions of AS systems collected from WWTPs located worldwide. The predictive accuracy R-1:1(2) of the Shannon-Wiener index reached 60.42%, and the average R-1:1(2) of amplicon sequence variants (ASVs) appearing in at least 10% of samples and core taxa were 35.09% and 42.99%, respectively. We also found that the predictability of ASVs was significantly positively correlated with their relative abundance and occurrence frequency, but significantly negatively correlated with potential migration rate. The typical functional groups such as nitrifiers, denitrifiers, polyphosphate-accumulating organisms (PAOs), glycogen-accumulating organisms (GAOs), and filamentous organisms in AS systems could also be well recovered using ANN models, with R-1:1(2) ranging from 32.62% to 56.81%. Furthermore, we found that whether industry wastewater source contained in inflow (IndConInf) had good predictive abilities, although its correlation with ASVs in the Mantel test analysis was weak, which suggested important factors that cannot be identified using traditional methods may be highlighted by the ANN model.
Conclusions We demonstrated that the microbial compositions and major functional groups of AS systems are predictable using our approach, and IndConInf has a significant impact on the prediction. Our results provide a better understanding of the factors affecting AS communities through the prediction of the microbial community of AS systems, which could lead to insights for improved operating parameters and control of community structure.
Source
MICROBIOME
Volume11Issue1
DOI10.1186/s40168-023-01519-9
2023年4月
Improving Rhamnolipids Biosynthesis in Pseudomonas sp. L01 through Atmospheric and Room-Temperature Plasma (ARTP) Mutagenesis
Ying Xu, Yali Jing, Qun Zhang, Jianlong Xiu, Maozhang Tian, Qingfeng Cui, Yuandong Ma, Lina Yi, Lu Han, Yuchen Qian, Yaqian Zhang, Yong Nie, and Xiao-Lei Wu
Abstract
Biosurfactants have significant applications in various industries, including microbialenhanced oil recovery (MEOR). While the state-of-the-art genetic approaches can generate high-yield strains for biosurfactant production in fermenters, there remains a critical challenge in enhancing biosurfactant-producing strains for use in natural environments with minimal ecological risks. The objectives of this work are enhancing the strain's capacity for rhamnolipids production and exploring the genetic mechanisms for its improvement. In this study, we employed atmospheric and roomtemperature plasma (ARTP) mutagenesis to enhance the biosynthesis of rhamnolipids in Pseudomonas sp. L01, a biosurfactant-producing strain isolated from petroleum-contaminated soil. Following ARTP treatment, we identified 13 high-yield mutants, with the highest yield of 3.45 +/- 0.09 g/L, representing a 2.7-fold increase compared to the parent strain. To determine the genetic mechanisms behind the enhanced rhamnolipids biosynthesis, we sequenced the genomes of the strain L01 and five high-yield mutants. A comparative genomic analysis suggested that mutations in genes related to the synthesis of lipopolysaccharides (LPS) and the transport of rhamnolipids may contribute to the improved biosynthesis. To the best of our knowledge, this is the first instance of utilizing the ARTP approach to improve rhamnolipid production in Pseudomonas strains. Our study provides valuable insights into the enhancement of biosurfactant-producing strains and the regulatory mechanisms of rhamnolipids biosynthesis.
Source
MICROORGANISMS
Volume11Issue5
DOI10.3390/microorganisms11051182
2023年6月
Assembly of Microbial Communities Engaging in Metabolic Division of Labor in a Diffusion-Limited Environment Is Governed by Metabolic Flux
Xiaoli Chen, Miaoxiao Wang, Yexin Xing, Yong Nie*, Xiao-Lei Wu*
Abstract
Metabolic division of labor (MDOL) represents one ofthe most commonlyoccurring interactions within natural microbial communities. Specifically,in a variety of MDOL systems engaged in hydrocarbon degradation, asequential degradation is performed by several members with finalproducts that are necessary for the growth of each member. In theseMDOL systems, each strain catalyzes one or more specific reactionsof a multistep metabolic pathway, whose end products are then allocatedamong the participants. While the benefit allocation is independentof metabolic flux in well-mixed environments, it remains unclear howthe benefits are allocated when diffusion is limited. Here, we investigatedhow MDOL communities assemble in a diffusion-limited environment,by combining mathematical modeling with experimental inquiry usinga synthetic consortium engaged in MDOL. Our model analysis in a diffusion-limitedenvironment showed that, when the growth of all populations in thecommunity relies on the final product that can only be produced bythe last population, a diffusion gradient of the final products maycreate a bias favoring the member producing the final products, resultingin a higher relative abundance of the final product producer. Moreover,such asymmetric allocation of the final products is enhanced by boththe lower diffusion rate and the higher metabolic flux (i.e., thehigher yields of the final products) in the MDOL. Our results showthat in a diffusively confined environment, metabolic flux constitutesa determining factor in the assembly of the MDOL community. Together,our findings are critical for a better understanding of how resource-sharingmicrobial communities are established and should assist in designingsuch communities for improved biomanufacturing and bioremediation.
Source
ACS SYNTHETIC BIOLOGY
Volume12Issue7Page1972-1980
DOI10.1021/acssynbio.3c00022
2023年8月
Light Induction of Seed Culture Accelerates Lutein Accumulation in Heterotrophic Fermentation of Chlorella protothecoides CS-41
Yunlei Fu, Lanbo Yi, Shufang Yang, Xue Lu, Bin Liu, Feng Chen, Junchao Huang, Kawing Cheng, Han Sun,* and Xiaolei Wu*
Abstract
Microalgae are recognized as a promising and valuable source of lutein. However, the current two-stage method for lutein production has drawbacks, such as complex operations and a long cultivation time. Additionally, utilizing heterotrophic fermentation to cultivate microalgae for lutein production leads to low lutein content due to the absence of light. In this study, we proposed a novel cultivation method that involves light induction of the seed culture to enhance lutein production during the heterotrophic cultivation phase of Chlorella protothecoides CS-41. To gain comprehensive insights into the underlying mechanisms of this method, we conducted qualitative and quantitative analyses of specific metabolites related to central carbon metabolism. The results revealed that low-light induction of seeds exhibited higher carbon efficiency compared to cells continuously subjected to heterotrophic cultivation, which may explain the observed increase in biomass and lutein content in cultures. Cultures after low-light induction of seed exhibited significantly higher lutein content (2.71 mg/g), yield (66.49 mg/L) and productivity (8.59 mg/L/d) compared to those consistently cultivated under heterotrophic conditions (2.37 mg/g, 37.45 mg/L, 4.68 mg/L/d). This cultivation strategy effectively enhances lutein yields, reduces production costs and holds the potential for broader application in other algal species for pigment production.
Source
FERMENTATION-BASEL
Volume9Issue8
DOI10.3390/fermentation9080768
2023年8月
Application prospect of lure technology by robotic fish in fish collection process
SHI Xiaotao, ZHOU Liuqing, LIN Chenyu, CHEN Jun, LIU Zhenbiao, XIE Guangming
Abstract
The use of biomimetic robotic fish to regulate fish behavior is of great significance in the conservation of fish resources, providing a new idea for the development of fish repellent technology. Based on the research status of robotic fish, we analyzed the visual luring mechanism, wake field luring mechanism, and electric signal luring mechanism of robotic fish lure technology. Moreover, we summarized the main factors affecting the fish luring technology of robotic fish and the relevant research achievements of foreign robotic fish regulating fish behavior, and discussed the application prospect of fish luring technology of robotic fish. This review would provide reference for the further development of fish luring technology of robotic fish in China.
Source
Chinese Journal of Ecology
2023, Vol. 42 Issue (5): 1225-1233.
doi: 10.13292/j.1000-4890.202303.030
2023年8月
The Influences of Self-Introspection and Credit Evaluation on Self-Organized Flocking
Qiang Zhao, Yu Luan, Shuai Li,* Gang Wang, Minyi Xu,* Chen Wang and Guangming Xie
Abstract
For biological groups, the behaviors of individuals will have an impact on the alignment efficiency of the collective movement. Motivated by Vicsek's pioneering research on self-organized particles and other related works about flocking behaviors, we propose two mathematical models based on the local information of individuals to include more realistic details in the interaction mechanism between individuals and the rest of the group during the flocking process. The local information of the individual refers to the local consistency, representing the degree of alignment with its neighbors. These two models are the self-introspection model, where the process of orientation adjustment of one individual is ruled by the degree of local consistency with the neighborhood, and the credit evaluation model, where the average orientation of the neighborhoods is weighed using the local consistency of the interacting individuals. Different metrics are calculated to analyze the effects of the model parameters and flocking parameters on groups. Simulation calculations indicate that the two improved models have certain advantages in terms of alignment efficiency for the group. Finally, the optimal model parameters are determined, and the effects of random noise on groups with a single behavior and mixed behaviors are analyzed. The results confirm that individuals with mixed behaviors still possess robustness against noise. This research would contribute to the further interdisciplinary cooperation that involves biology, ethology, and multi-agent complex systems.
Source
APPLIED SCIENCES-BASEL
Volume13Issue18
DOI10.3390/app131810361
2023年9月
Mucosal bleeding correlates with submucosal microbial dysbiosis in peri-implant mucositis of patients with periodontitis
Siqi Li, Fei Sun, Yiping Wei, Yong Nie, Xiaolei Wu, Wenjie Hu
Abstract
Objectives: This study aimed to investigate the relationship between microbial communities and the severity of peri-implant mucosal bleeding in peri-implant mucositis.Materials and Methods: Submucosal plaque samples were collected from 54 implants divided into the healthy implant (HI) group, peri-implant mucositis (PM) group, and peri-implantitis (PI) group. Sequencing of 16S rRNA was performed using the Illumina MiSeq platform. Alpha diversity (i.e., Shannon and Chao index) and beta diversity were used to measure microbial diversity within and between microbial communities, respectively. Differences in microbial taxa between groups were assessed via linear discriminate analysis effect size. Correlation between the modified sulcus bleeding index (mSBI) and microbial dysbiosis index (MDI) was examined using Spearman correlation analysis and linear models.Results: The submucosal bacterial richness (Chao index) was positively correlated with the mean mSBI in the PM group. As the mean mSBI increased in the PM group, the beta diversity became closer to that of the PI group. In the PM group, the abundances of 47 genera were significantly correlated with the mean mSBI, and the MDI was positively associated with the mean mSBI. Fourteen of the forty-seven genera were discriminative taxa between the HI and PI groups, and the abundances of these biomarkers became closer to those in the PI group in the progression of peri-implant disease.Conclusions: A higher mSBI value corresponded to a higher risk of microbial dysbiosis in peri-implant mucositis. The biomarkers identified may be useful for monitoring the progression of peri-implant disease.
Source
CLINICAL ORAL IMPLANTS RESEARCH
Volume34Issue9Page947-957
DOI10.1111/clr.14120
2023年9月
Roles of sulfate-reducing bacteria in sustaining the diversity and stability of marine bacterial community
An, Liyun; Yan, Ying-Chun ; Tian, Hai-Long ; Chi, Chang-Qiao; Nie, Yong; Wu, Xiao-Lei
Abstract
Microbes play central roles in ocean food webs and global biogeochemical processes. Yet, the information available regarding the highly diverse bacterial communities in these systems is not comprehensive. Here we investigated the diversity, assembly process, and species coexistence frequency of bacterial communities in seawater and sediment across similar to 600 km of the eastern Chinese marginal seas using 16S rRNA gene amplicon sequencing. Our analyses showed that compared with seawater, bacterial communities in sediment possessed higher diversity and experienced tight phylogenetic distribution. Neutral model analysis showed that the relative contribution of stochastic processes to the assembly process of bacterial communities in sediment was lower than that in seawater. Functional prediction results showed that sulfate-reducing bacteria (SRB) were enriched in the core bacterial sub-communities. The bacterial diversities of both sediment and seawater were positively associated with the relative abundance of SRB. Co-occurrence analysis showed that bacteria in seawater exhibited a more complex interaction network and closer co-occurrence relationships than those in sediment. The SRB of seawater were centrally located in the network and played an essential role in sustaining the complex network. In addition, further analysis indicated that the SRB of seawater helped maintain the high stability of the bacterial network. Overall, this study provided further comprehensive information regarding the characteristics of bacterial communities in the ocean, and provides new insights into keystone taxa and their roles in sustaining microbial diversity and stability in ocean.
Source
FRONTIERS IN MICROBIOLOGY
Volume14
DOI10.3389/fmicb.2023.1218828
2023年9月
Volatile compounds-induced environmental pH shifts mediate interspecific bacterial interactions over long-distance
Na Luo, Miaoxiao Wang, Yong Nie, Xiao-Lei Wu
Abstract
Microorganisms interact with each other through exchanging metabolites as well as signals molecules. This exchange typically depends on metabolites or signaling molecules diffusing in aqueous media within spatially connected habitats, and it only occurs within a short range. However, different microorganisms frequently live in spatially discontinuous micro-habitats without the connections of aqueous media. How microorganisms populating such spatially discontinuous micro-habitats interact remains poorly understood. Here, we show that a bacterial strain, Corynebacterium glutamicum ATCC13032T, produces high amounts of ammonia in its local habitat, which disperses over long distances (up to 12 cm) through the air. As a result, the pH of another spatially disconnected habitat increases, thus inducing the growth of an acid-sensitive strain (Glycocaulis alkaliphilus 6B-8T). We also show that ammoniamediated long-distance interactions can be commonly found in various bacterial communities. In conclusion, our work demonstrates that bacteria growing in spatially discontinuous micro-habitats can interact with each other through gaseous diffusion of volatile compounds. This finding expands our understanding of the spatial scale at which bacteria can interact and provides new insights into how spatially separated species are connected to maximizing community-level commensalism.
Source
SCIENCE OF THE TOTAL ENVIRONMENT
Volume892
DOI10.1016/j.scitotenv.2023.164577
2023年10月
Heat Transport Processes of the Indonesian Throughflow Along the Outflow Pathway in the Eastern Indian Ocean During the Last 160 Kyr
Xuan Ding, Franck Bassinot, Xiaolei Pang, Yingxin Kou, Liping Zhou
Abstract
As the only low-latitude connection along the return branch of the Great Conveyor Belt, the Indonesian Throughflow (ITF) plays an important role in the large-scale ocean–atmosphere interaction in the tropical region. However, the heat transport processes of the ITF along the outflow pathway in the eastern Indian Ocean over the recent geologic period is still debated. In this study, by using Mg/Ca ratios of the surface-dwelling and thermocline-dwelling planktonic foraminifera Globigerinoides ruber and Pulleniatina obliquiloculata, we reconstruct sea surface temperature and thermocline water temperature (TWT), and thermocline structure at two sites in the main outflow path of the ITF in the eastern Indian Ocean for the last 160 Kyr, and compare these new data with those from two cores in the central Indo-Pacific Warm Pool. Our results show that, on the orbital time scale, the thermocline structure changes above the equatorial 90°E Ridge mimic those of the eastern Timor Sea, indicating that the ITF vertical structure remained unchanged during its penetration into the Indian Ocean. The TWT in the equatorial western Pacific and eastern Indian Ocean presents similar change trend, suggesting that the ITF is likely to be an important route for thermocline water transport into the Indian Ocean. However, the vertical structure of the ITF varied through time, reflecting the effects of sea level and orbitally-driven monsoonal activity. This impacted heat transport processes, resulting in changes in the surface water temperature along the outflow pathway in the eastern Indian Ocean.
Source
PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY
Volume38Issue10
DOI10.1029/2023PA004620
2023年11月
A novel scheme for time-fractional semi-relativistic Vlasov–Maxwell system based on laser-plasma interaction with linear polarization and Landau damping instability
Zubair, Tamour; Lu, Tiao; Usman, Muhammad
Abstract
The Vlasov-Maxwell system is a revolutionary tool to model and analyze the dynamic behavior of the collisionless plasma in the existence of the electromagnetic field. In this perspective, the investigation of this system with the concept of the time-fractional derivative is the new benchmark and also one of the main objectives of this article. To construct the numerical solution, we propose and implement a novel scheme which grounded on finite-difference and spectral approximations. The temporal variables are tackled by using finite-difference approximations, whereas spatial variables approximated via sifted Gegenbauer polynomials. Various simulations are performed to explore new phenomena, demonstrate the accuracy and reliability of the proposed method. Convergence, error bound and stability of the suggested methods are investigated numerically. Moreover, the developed method can be used conveniently to examine the numerical solution of other multidimensional highly nonlinear fractional or variable order problems of physical nature.
Source
NUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS
Volume39Issue6Page4432-4453
DOI10.1002/num.22611
2023年11月
Hydrogen peroxide oxidation modifies the structural properties and allergenicity of the bee pollen allergen profilin
Enning Zhou, Weiwei Wang, Xiaofeng Xue, Pianpian Wang, Fan Wu, Liming Wu, Qiangqiang Li
Abstract
Bee pollen is a byproduct of pollination, which is a necessary process to produce foods. However, bee pollen can induce significant food-borne allergies. We previously identified a bee pollen-derived pan-allergen in the profilin family, Bra c p. Herein, we aimed to reduce Bra c p allergenicity via protein oxidation with hydrogen peroxide and explore the changes induced. Ion-mobility mass spectrometry revealed aggregation of the oxidized product; we also found irreversible sulfonation of the free sulfhydryl group of the Bra c p Cys98 residue to a more stable cysteine derivative. A significant proportion of the & alpha;-helices in Bra c p were transformed into & beta;-sheets after oxidation, masking the antigenic epitopes. An immunoassay demonstrated that the IgE-binding affinity of Bra c p was decreased in vitro after oxidation. To our knowledge, this is the first report describing the application of protein oxidation to reduce the allergenicity of profilin family member in foods.
Source
FOOD CHEMISTRY
Volume425
DOI10.1016/j.foodchem.2023.136495
