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Opportunities and challenges in studies of mammalian hybrid speciation

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Science China(life Sciences) 2024年第3期67卷 614-617页

作者： Hong Wu yuxing Zhang li Yu State Key Laboratory for Conservation and Utilization of Bio-Resource in Yunnan School of Life SciencesYunnan UniversityKunming 650091China

Revealing the mechanisms of speciation remains one of the most attractive and challenging issues in the field of evolutionary biology, and is also key to understanding the biodiversity present in nature.

关键词： biodiversity attractive evolutionary

Microscopic morphology evolution of the crystal structure of tetrahydrofuran hydrate under flowing condition

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Chinese Journal of Chemical Engineering 2022年第5期35卷 103-110页

作者： Jialu Zhang Xiang liu Shuai liu Yuxing Li Qihui Hu Wuchang Wang Shandong Key Laboratory of Oil-Gas Storage and Transportation Safety College of Pipeline and Civil EngineeringChina University of Petroleum(East China)Qingdao 266580China State Key Loboratory of Natural Gas Hydrates Beijing 100028China

The evolution of the hydrate particle structure during growth and agglomeration under flowing condition affects the particle as well as flow characteristic,which plays an important role in the flow assurance as well as heat transfer in refrigeration systems.Therefore,this article conducts experiments to study and observe the growth and agglomeration process in the main forming stage of hydrate.It was found that the growth of tetrahydrofuran hydrate was anisotropic and in a layered growth pattern.Single crystals generally transformed from octahedral structure to octahedral skeleton structure with growth,however some single crystals also deformed into plate type particles.The thickness of the plate type particles increased gradually during growth,and the edge part increased earlier than the middle part.During agglomeration,the hydrate particles contacted and sintered together.Sand as the impurity didn’t serve as the nucleation center but affected the agglomeration of hydrate particles by collisions.In addition,the effect increased as the sand size decreased.Finally,a microstructure model for hydrate growth and agglomeration was proposed,which showed the hydrate structure evolution in these processes and could lay a foundation for studying the flow assurance of hydrate slurry.

关键词： Tetrahydrofuran hydrate Growth Agglomeration Morphology Microstructure Microstructure model

Growth and aggregation micromorphology of natural gas hydrate particles near gas-liquid interface under stirring condition

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Chinese Journal of Chemical Engineering 2021年第12期34卷 65-77页

作者： Qihui Hu Xiaoyu Wang Wuchang Wang Yuxing Li Shuai liu Shandong Key Laboratory of Oil-Gas Storage and Transportation Safety College of Pipeline and Civil EngineeringChina University of PetroleumQingdao 266580China State Key Laboratory of Natural Gas Hydrates Beijing 100028China Research Institute of Experiment and Detection Petro China Xinjiang Oilfield CompanyKaramay 834000China

To investigate the morphological evolution of the whole growth and aggregation processes of hydrate crystals near the gas–liquid interface,we used a high-pressure visual reactor with high-speed camera to capture the micromorphology of hydrate particles in a natural gas+pure water system with pressure from 2.6 to 3.6 MPa and sub-cooling from 4.7 to 6.23C.The results showed that under low sub-cooling conditions,the amount and size of particles increased first and then decreased in the range of 0–330 lm,and the small particles always dominated.These particles can be roughly classified into two categories:planar flake particles and polyhedral solid particles.Then,the concept of maximum growth dominant particle size was proposed to distinguish the morphological boundary of growth and aggregation.In addition,the micro model was established to better reflect the effects of particle formation process and evolution mechanism near the gas–liquid interface under stirring condition.The results of this study can provide a guidance for flow assurance in multiphase pipeline.

关键词： Natural gas hydrate Growth Aggregation Gas-liquid interface Micromorphology Physical model

Numerical Study of Heat Transfer Characteristic for Subcooled Falling Film outside the Shaped Tubes under Rolling Motion

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Journal of Thermal Science 2023年第3期32卷 922-932页

作者： HAN Hui WANG Junqi WANG Shaowei li yuxing Provincial Key Laboratory of Oil and Gas Storage and Transportation Safety in Shandong Province China University of Petroleum(Huadong)Qingdao 266580China

The heat transfer performance of spiral wound heat exchanger used in the floating liquefied natural gas(FLNG)may be significantly affected by the sloshing conditions.In this paper,a three-dimensional numerical model combined with the dynamic mesh technology is conducted to study subcooled falling film heat transfer under static and sloshing conditions.The three-dimensional velocity distribution of the liquid film on the shell side is observed.The effects of cross-section shape of heat exchange tubes,Reynolds numbers and sloshing parameters on heat transfer characteristics are analyzed.The results indicate that the heat transfer performance of the egg-shaped tube is superior to that of the elliptical and circular tube under both static and sloshing conditions due to significant heat transfer improvement in the lower half of the tube.The heat transfer coefficients of three different kinds of tubes decrease under sloshing conditions.When the rolling amplitude is 6°,the average heat transfer coefficients of the circular tube,elliptical tube and egg-shaped tube are reduced by 2.1%,3.7%and 4.9%respectively.Under the current sloshing parameters,increasing the rolling amplitude,the heat transfer coefficients of three different tubes are slightly increased,while the sloshing period has little effect on heat transfer.The egg-shaped tube and elliptical tube are greatly affected by sloshing motion at the low Reynolds number,while the effect is relatively small at the high Reynolds number.

关键词： falling film flow sloshing condition spiral wound heat exchanger floating liquefied natural gas

Characteristics of Salvia miltiorrhiza methylome and the regulatory mechanism of DNA methylation in tanshinone biosynthesis

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Horticulture Research 2023年第7期10卷 265-279页

作者： Jiang li Caili li yuxing Deng Hairong Wei Shanfa Lu Key Lab of Chinese Medicine Resources Conservation State Administration of Traditional Chinese Medicine of the People’s Republic of ChinaInstitute of Medicinal Plant DevelopmentChinese Academy of Medical Sciences&Peking Union Medical CollegeBeijing 100193China Engineering Research Center of Chinese Medicine Resource Ministry of EducationBeijing 100193China College of Forest Resources and Environmental Science Michigan Technological UniversityHoughtonMI 49931USA

Salvia miltiorrhiza is a model medicinal plant with significant economic and medicinal value.Its roots produce a group of diterpenoid lipophilic bioactive components,termed tanshinones.Biosynthesis and regulation of tanshinones has attracted widespread interest.However,the methylome of S.miltiorrhiza has not been analysed and the regulatory mechanism of DNA methylation in tanshinone production is largely unknown.Here we report single-base resolution DNA methylomes from roots and leaves.Comparative analysis revealed differential methylation patterns for CG,CHG,and CHH contexts and the association between DNA methylation and the expression of genes and small RNAs.Lowly methylated genes always had higher expression levels and 24-nucleotide sRNAs could be key players in the RdDM pathway in S.miltiorrhiza.DNA methylation variation analysis showed that CHH methylation contributed mostly to the difference.Go enrichment analysis showed that diterpenoid biosynthetic process was significantly enriched for genes with downstream overlapping with hypoCHHDMR in July_root when comparing with those in March_root.Tanshinone biosynthesis-related enzyme genes,such as DXS2,CMK,IDI1,HMGR2,DXR,MDS,CYP76AH1,2OGD25,and CYP71D373,were less CHH methylated in gene promoters or downstream regions in roots collected in July than those collected in March.Consistently,gene expression was up-regulated in S.miltiorrhiza roots collected in July compared with March and the treatment of DNA methylation inhibitor 5-azacytidine significantly promoted tanshinone production.It suggests that DNA methylation plays a significant regulatory role in tanshinone biosynthesis in S.miltiorrhiza through changing the levels of CHH methylation in promoters or downstreams of key enzyme genes.

关键词： miltiorrhiza roots mechanism

Wave propagation analysis of porous functionally graded piezoelectric nanoplates with a visco-Pasternak foundation

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Applied Mathematics and Mechanics(English Edition) 2023年第1期44卷 35-52页

作者： Zhaonian li Juan liU Biao HU yuxing WANG Huoming SHEN Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China

This study investigates the size-dependent wave propagation behaviors under the thermoelectric loads of porous functionally graded piezoelectric(FGP) nanoplates deposited in a viscoelastic foundation.It is assumed that(i) the material parameters of the nanoplates obey a power-law variation in thickness and(ii) the uniform porosity exists in the nanoplates.The combined effects of viscoelasticity and shear deformation are considered by using the Kelvin-Voigt viscoelastic model and the refined higher-order shear deformation theory.The scale effects of the nanoplates are captured by employing nonlocal strain gradient theory(NSGT).The motion equations are calculated in accordance with Hamilton’s principle.Finally,the dispersion characteristics of the nanoplates are numerically determined by using a harmonic solution.The results indicate that the nonlocal parameters(NLPs) and length scale parameters(LSPs) have exactly the opposite effects on the wave frequency.In addition,it is found that the effect of porosity volume fractions(PVFs) on the wave frequency depends on the gradient indices and damping coefficients.When these two values are small,the wave frequency increases with the volume fraction.By contrast,at larger gradient index and damping coefficient values,the wave frequency decreases as the volume fraction increases.

关键词： scale effect functionally graded material(FGM) dispersion characteristic piezoelectric nanoplate viscoelastic foundation

An experimental study on the choked flow characteristics of CO_(2) pipelines in various phases

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Chinese Journal of Chemical Engineering 2021年第4期34卷 17-26页

作者： Yuxing Li Shuaiwei Gu Datong Zhang Qihui Hu lin Teng Cailin Wang Shandong Provincial Key Laboratory of Oil&Gas Storage and Transportation Security China University of Petroleum(East China)Qingdao 266555China Department of Energy and Power Engineering Tsinghua UniversityBeijing 100084China

High pressure pipeline transportation has been an established technology for economically transporting large amounts of CO_(2).However,there are still issues and associated risks that have to be effectively addressed and adequately understood.It is well known that a strong JouleThomson Cooling effect can occur when pressurized CO_(2) flows through a choke valve.Thus,to investigate the choking characteristics especially the temperature drop of high pressure CO_(2),a new laboratory scale experimental setup(total length of 14.85 m and the inner diameter of 15 mm)was constructed.Steady choked flow and transient choked flow tests were carried out respectively for pressurized CO_(2) in various initial phases.The phase transitions and temperature drop characteristics were then studied following the choked flow and the results show that the phase transitions in steady choked flow differs significantly from that in transient choked flow.For transient choked flow of various initial phases,all the flows downstream would transfer from single phase to gas-liquid twophase flow.Furthermore,the effect of water on transient choked flow of supercritical CO_(2) pipeline was investigated,and the phenomena of solid particles deposition was captured which was paramount importance of ensuring the safety operation of CO_(2)pipelines when throttling by the choke valves.

关键词： CO^(2)pipeline Steady choked flow Transient choked flow Water Temperature drop

Hydrate formation in oil–water systems: Investigations of the influences of water cut and anti-agglomerant

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Chinese Journal of Chemical Engineering 2020年第2期28卷 369-377页

作者： Guangchun Song Yuxing Li Wuchang Wang Kai Jiang Zhengzhuo Shi Shupeng Yao Shandong Province Key Laboratory of Oil-Gas Storage and Transportation Safety China University of PetroleumQingdao 266580China

To investigate the characteristics of hydrate formation in oil–water systems, a high-pressure cell equipped with visual windows was used where a series of hydrate formation experiments were performed from natural gas + diesel oil + water systems at different water cuts and anti-agglomerant concentrations. According to the temperature and pressure profiles in test experiments, the processes of hydrate formation under two kinds of experimental procedures were analyzed first. Then, based on the experimental phenomena observed through the visual windows, the influences of water cut and anti-agglomerant on the places of hydrate formation and distribution, hydrate morphologies and hydrate morphological evolvements were investigated. Hydrate agglomeration, hydrate deposition and hydrate film growth on the wall were observed in experiments. Furthermore, three different mechanisms for hydrate film growth on the wall were identified. In addition, the influences of water cut and anti-agglomerant on the induction time of hydrate formation were also studied.

关键词： Hydrates Formation Oil–water system Water cut Anti-agglomerant

Leak Detection of Gas Pipelines Based on Characteristics of Acoustic Leakage and Interfering Signals

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Sound & Vibration 2019年第4期53卷 111-128页

作者： lingya Meng Cuiwei liu liping Fang Yuxing Li Juntao Fu College of Information and Control Engineering China University of PetroleumQingdaoChina. Provincial Key Laboratory of Oil and Gas Storage and Transportation Safety University of PetroleumQingdaoChina. China SINOPEC Natural Gas Corporation BeijingChina.

When acoustic method is used in leak detection for natural gas pipelines,the external interferences including operation of compressor and valve,pipeline knocking,etc.,should be distinguished with acoustic leakage signals to improve the accuracy and reduce false alarms.In this paper,the technologies of extracting characteristics of acoustic signals were summarized.The acoustic leakage signals and interfering signals were measured by experiments and the characteristics of time-domain,frequency-domain and time-frequency domain were extracted.The main characteristics of time-domain are mean value,root mean square value,kurtosis,skewness and correlation function,etc.The features in frequency domain were obtained by frequency spectrum analysis and power spectrum density,while time-frequency analysis was accomplished by short time Fourier transform.The results show that the external interferences can be removed effectively by the characteristics of time domain,frequency domain and time-frequency domain.It can be drawn that the acoustic leak detection method can be applied to natural gas pipelines and the characteristics can help reduce false alarms and missing alarms.

关键词： Leak detection acoustic method signal processing external interference characteristic extraction