Coupled microbial bloom and oxygenation decline recorded by magnetofossils during the Palaeocene-Eocene Thermal Maximum
Chang, L., R. J. Harrison, F. Zeng, T.，Berndt, A. P. Roberts, D. Heslop, X. Zhao
Understanding marine environmental change and associated biological turnover across the Palaeocene-Eocene Thermal Maximum(PETM; -56 Ma)-themost pronounced Cenozoic short-term global warming event-is important because of the potential role of the ocean in atmospheric CO2 drawdown, yet proxies for tracing marine productivity and oxygenation across the PETM are limited and results remain controversial. Here we show that a high-resolution record of South Atlantic Ocean bottom water oxygenation can be extracted from exceptionally preserved magnetofossils-the bioinorganic magnetite nanocrystals produced b ymagnetotactic bacteria (MTB) using a new multiscale environmental magnetic approach. Our results suggest that a transient MTB bloom occurred due to increased nutrient supply. Bottom water oxygenation decreased gradually from the onset to the peak PETM. These observations provide a record of microbial response to the PETM and establish the value of magnetofossils as palaeo environmental indicators.
Chang, L., R. J. Harrison, F. Zeng, T. Berndt, A. P. Roberts, D. Heslop, X. Zhao, (2018). Coupled microbial bloom and oxygenation decline recorded by magnetofossils during the Palaeocene-Eocene Thermal Maximum, Nature Communications, 4007, DOI: 10.1038/s41467-018-06472-y.
Acousto-Optic Modulation Induced Noises on Heterodyne-Interrogated Interferometric Fiber-Optic Sensors
Liu, F (Liu, Fei)[ 1,2 ] ; Gu, LJ (Gu, Lijuan)[ 3 ] ; Xie, SR (Xie, Shangran)[ 4 ] ; He, XG (He, Xiangge)[ 1,2 ] ; Yi, D (Yi, Duo)[ 1,2 ] ; Zhang, M (Zhang, Min)[ 1,2 ] ; Tao, QC (Tao, Qingchang)[ 5 ]
Acousto-optic modulator (AOM) is a key component in heterodyne-interrogated interferometric fiber-optic sensors. Here, we analyze in detail the effect of AOM on the noise floor of interferometric fiber-optic sensors with heterodyne detection. Besides the well-known phase noises caused by the AOM driver, the intensity noise induced by the relative diffraction efficiency fluctuation (RDEF) of AOM is considered and for the first time studied in detail. The power spectrum density of the intensity noise is found 0.8-0.9 times of the "switching noise," which is defined as the sum of RDEF and relative intensity noise of the laser. The switching noise varies with the driving power of AOM and can be reduced by setting the driving power close to its saturation point. Experimentally, we achieved similar to 5-dB suppression of the switching noise and similar to 2-dB reduction of the overall noise floor. By working at the optimal driving power, together with reducing the AOM-induced phase noise to -130 dB level at the frequency offset twice of the heterodyne frequency, the overall noise floor of the sensor can be optimized to about -101 dB, i.e., the order of 10 mu rad/root Hz.
Liu, F.; Gu, L. J.; Xie, S. R.; He, X. G.; Yi, D.; Zhang, M.; Tao, Q. C., Acousto-Optic Modulation Induced Noises on Heterodyne-Interrogated Interferometric Fiber-Optic Sensors.J. Lightwave Technol.2018,36(16), 3465-3471.
Brasilianoids A–F, New Meroterpenoids From the Sponge-Associated Fungus Penicillium brasilianum
Jianping Zhang, 1 Bochuan Yuan, 1 Dong Liu, 1 Shuang Gao, 2 Peter Proksch, 3 andWenhan Lin1,*
3,5-Dimethylorsellinic acid (DMOA) derived meroterpenoids comprise an unique class of natural products with diverse scaffolds and with a broad spectrum of bioactivities. Bioinformatics analysis of the gene clusters in association with the qRT-PCR detection of the amplification of two key genes led to speculate that the sponge associated fungus Penicillium brasilianum WZXY-m122-9 is a potential producer of meroterpenoids. Chromatographic separation of the EtOAc extract of this fungal strain on a large-scale fermentation resulted in the isolation of six new DMOA-related meroterpenoids with trivial names of brasilianoids A-F (1-6), together with preaustinoid D and preaustinoid A2. The structures were determined by extensive analyses of spectroscopic data, including the X-ray diffraction and the ECD data for configurational assignment. Brasilianoids A and F showed an unprecedented skeleton with a gamma-lactone in ring A, while brasilianoids B-C featured a 7/6/6/5/5 pentacyclic ring system finding in nature for the first time. The biosynthetic relationship among the isolated compounds was postulated. Compound 1 significantly stimulated the expression of filaggrin and caspase-14 in HaCaT cells in dose-dependent manner, while compounds 2 and 3 showed moderate inhibition against NO production in LPS-induced RAW 264.7 macrophages.
Zhang J, Yuan B, Liu D, et al. Brasilianoids A–F, New Meroterpenoids From the Sponge-Associated Fungus Penicillium brasilianum[J]. Frontiers in Chemistry, 2018, 6.
Palaeoclimate constraints on the impact of 2 degrees C anthropogenic warming and beyond (vol 11, pg 474, 2018).
liping Zhou, etc.
Fischer, H.; Meissner, K. J.; Mix, A. C.; Abram, N. J.; Austermann, J.; Brovkin, V.; Capron, E.; Colombaroli, D.; Daniau, A.-L.; Dyez, K. A.; Felis, T.; Finkelstein, S. A.; Jaccard, S. L.; McClymont, E. L.; Rovere, A.; Sutter, J.; Wolff, E. W.; Affolter, S.; Bakker, P.; Ballesteros-Canovas, J. A.; Barbante, C.; Caley, T.; Carlson, A. E.; Churakova, O.; Cortese, G.; Cumming, B. F.; Davis, B. A. S.; de Vernal, A.; Emile-Geay, J.; Fritz, S. C.; Gierz, P.; Gottschalk, J.; Holloway, M. D.; Joos, F.; Kucera, M.; Loutre, M.-F.; Lunt, D. J.; Marcisz, K.; Marlon, J. R.; Martinez, P.; Masson-Delmotte, V.; Nehrbass-Ahles, C.; Otto-Bliesner, B. L.; Raible, C. C.; Risebrobakken, B.; Goni, M. F. S.; Arrigo, J. S.; Sarnthein, M.; Sjolte, J.; Stocker, T. F.; Alvarez, P. A. V.; Tinner, W.; Valdes, P. J.; Vogel, H.; Wanner, H.; Yan, Q.; Yu, Z.; Ziegler, M.; Zhou, L., Palaeoclimate constraints on the impact of 2 degrees C anthropogenic warming and beyond (vol 11, pg 474, 2018). Nature Geoscience 2018, 11 (8), 615-615.
Self-Referenced Accelerometer Array Multiplexed on a Single Fiber Using a Dual-Pulse Heterodyne Phase-Sensitive OTDR
Xiangge He,Min Zhang, Shangran Xie, Fei Liu, Lijuan Gu, andDuo Yi
We report a new type of multiplexed fiber-optic accelerometer array based on a dual-heterodyne-pulse phase-sensitive OTDR technique. This scheme significantly simplifies the structure of fiber accelerometer and can greatly benefit its practical applications. The sensitivity model for the new type accelerometer based on the Rayleigh backscattering is developed for the first time, which shows a great difference from the transmission-type interferometric accelerometer. On a single piece of telecommunication fiber, we demonstrate the multiplexing of three accelerometers separated by 20 m, each with a measured sensitivity of ∼36 rad/g that agrees well with the theoretical analysis. The connecting fiber between accelerometers simultaneously acts as a distributed acoustic sensor, which under proper vibration isolation can be used as a self-reference to suppress system noises. We show that the common-mode noises of the sensor can be suppressed by 35 dB at a frequency of 100 Hz without using additional reference interferometers.
He X, Zhang M, Xie S, et al. Self-Referenced Accelerometer Array Multiplexed on a Single Fiber Using a Dual-Pulse Heterodyne Phase-Sensitive OTDR[J]. Journal of Lightwave Technology, 2018, 36(14): 2973-2979.
Long-term viability of carbon sequestration in deep-sea sediments
Yihua Teng, andDongxiao Zhang
Sequestration of carbon dioxide in deep-sea sediments has been proposed for the long-term storage of anthropogenic CO2 that can take advantage of the current offshore infrastructure. It benefits from the negative buoyancy effect and hydrate formation under conditions of high pressure and low temperature. However, the multiphysics process of injection and postinjection fate of CO2 and the feasibility of subseabed disposal of CO2 under different geological and operational conditions have not been well studied. With a detailed study of the coupled processes, we investigate whether storing CO2 into deep-sea sediments is viable, efficient, and secure over the long term. We also study the evolution of multiphase and multicomponent flow and the impact of hydrate formation on storage efficiency. The results show that low buoyancy and high viscosity slow down the ascending plume and the forming of the hydrate cap effectively reduces permeability and finally becomes an impermeable seal, thus limiting the movement of CO2 toward the seafloor. We identify different flow patterns at varied time scales by analyzing the mass distribution of CO2 in different phases over time. We observe the formation of a fluid inclusion, which mainly consists of liquid CO2 and is encapsulated by an impermeable hydrate film in the diffusion-dominated stage. The trapped liquid CO2 and CO2 hydrate finally dissolve into the pore water through diffusion of the CO2 component, resulting in permanent storage. We perform sensitivity analyses on storage efficiency under variable geological and operational conditions. We find that under a deep-sea setting, CO2 sequestration in intact marine sediments is generally safe and permanent.
Teng Y, Zhang D. Long-term viability of carbon sequestration in deep-sea sediments[J]. Science advances, 2018, 4(7): eaao6588.
Asynchronous distributed event-triggered circle formation of multi-agent systems
Wen, Jiayan; Wang, Chen; Xie, Guangming
This paper proposes distributed event-triggered algorithmic solutions to circle formation problems of first-order multi-agent systems, where the communication topology of networks is described by weight-unbalanced, strongly connected digraph. In particular, the controller updates and communications between neighboring agents considered here are event-triggered, depending on the specified threshold of a certain measurement error by contrast with the norm of a function with state-dependent. Sufficient conditions on both uniform and arbitrary circle formation are derived under which the resulting asynchronous network executions converge to some equilibrium point. Furthermore, we show that the Zeno behavior can be avoided under the proposed control laws. Numerical simulation results are given to illustrate the effectiveness of the proposed methods.
Wen J, Wang C, Xie G. Asynchronous distributed event-triggered circle formation of multi-agent systems[J]. Neurocomputing, 2018, 295: 118-126.
Self-suppression of common-mode noises of the different fiber optic interferometric accelerometers
Yi Duo; He Xiangge; Liu Fei; Gu Lijuan; Zhang Min; Qiu Xiaokang; Ye Han
This study proposes two new fiber optic interferometric accelerometers with the utilization of the push-pull structure, one is based on the principle of triple low-reflectivity fiber Bragg gratings, and the other is based on the 1x3 unbalanced Michelson interferometer. The proposed accelerometers are capable of suppressing the common-mode noises (CMNs) by themselves without additional reference accelerometers, and therefore reducing the volume and the cost of the sensing system. Besides, the accelerometers can also suppress the sensor noises caused by the environment, and therefore show better CMNs suppression effect than the traditional method of using the reference accelerometer. The two accelerometers are experimentally verified and show respectively an improvement of 33 dB and 28 dB in CMNs suppression at 100 Hz. Both presented fiber optic accelerometers show huge advantages for the large-scale quasi-distributed oil and gas reservoir monitoring applications. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.
Duo Y, Xiangge H, Fei L, et al. Self-suppression of common-mode noises of the different fiber optic interferometric accelerometers[J]. Optics Express, 2018, 26(12): 15384-15397.
Two-scalar turbulent Rayleigh-Benard convection: numerical simulations and unifyingtheory.
Yang, YT (Yang, Yantao)[ 1,2,3,4 ] ; Verzicco, R (Verzicco, Roberto)[ 3,4,5 ] ; Lohse, D (Lohse, Detlef)[ 3,4,6 ]
We conduct direct numerical simulations for turbulent Rayleigh-Benard (RB) convection, driven simultaneously by two scalar components (say, temperature and concentration) with different molecular diffusivities, and measure the respective fluxes and the Reynolds number. To account for the results, we generalize the Grossmann-Lohse theory for traditional RB convection (Grossmann & Lohse, J. Fluid Mech., vol. 407, 2000, pp. 27-56; Phys. Rev. Lett., vol. 86 (15), 2001, pp. 3316-3319; Stevens etal., J. Fluid Mech., vol. 730, 2013, pp. 295-308) to this two-scalar turbulent convection. Our numerical results suggest that the generalized theory can successfully capture the overall trends for the fluxes of two scalars and the Reynolds number without introducing any new free parameters. In fact, for most of the parameter space explored here, the theory can even predict the absolute values of the fluxes and the Reynolds number with good accuracy. The current study extends the generality of the Grossmann-Lohse theory in the area of buoyancy-driven convection flows.
Yang, Y.; Verzicco, R.; Lohse, D., Two-scalar turbulent Rayleigh-Benard convection: numerical simulations and unifyingtheory. Journal of Fluid Mechanics 2018, 848, 648-659.
Precession and atmospheric CO2modulated variability of sea ice in the central Okhotsk Sea since 130,000 years ago
Li Lo, Simon T. Belt, Julie Lattaud, Tobias Friedrich, Christian Zeeden, Stefan Schouten, Lukas Smik, Axel Timmermann, Patricia Cabedo-Sanz, Jyh-Jaan Huang,Liping Zhou, Tsong-Hua Ou,Yuan-Pin Chang, Liang-Chi Wang, Yu-Min Chou, Chuan-Chou Shen, Min-Te Chen, Kuo-Yen Wei, Sheng-Rong Song, Tien-Hsi Fang, Sergey A. Gorbarenko, Wei-Lung Wang, Teh-Quei Lee, Henry Elderfield, David A. Hodell
Recent reduction in high-latitude sea ice extent demonstrates that sea ice is highly sensitive to external and internal radiative forcings. In order to better understand sea ice system responses to external orbital forcing and internal oscillations on orbital timescales, here we reconstruct changes in sea ice extent and summer sea surface temperature (SSST) over the past 130,000 yrs in the central Okhotsk Sea. We applied novel organic geochemical proxies of sea ice (IP25), SSST (TEXL86) and open water marine productivity (a tri-unsaturated highly branched isoprenoid and biogenic opal) to marine sediment core MD01-2414 (53°11.77′N, 149°34.80′E, water depth 1123 m). To complement the proxy data, we also carried out transient Earth system model simulations and sensitivity tests to identify contributions of different climatic forcing factors. Our results show that the central Okhotsk Sea was ice-free during Marine Isotope Stage (MIS) 5e and the early-mid Holocene, but experienced variable sea ice cover during MIS 2–4, consistent with intervals of relatively high and low SSST, respectively. Our data also show that the sea ice extent was governed by precession-dominated insolation changes during intervals of atmospheric CO2 concentrations ranging from 190 to 260 ppm. However, the proxy record and the model simulation data show that the central Okhotsk Sea was near ice-free regardless of insolation forcing throughout the penultimate interglacial, and during the Holocene, when atmospheric CO2 was above ∼260 ppm. Past sea ice conditions in the central Okhotsk Sea were therefore strongly modulated by both orbital-driven insolation and CO2-induced radiative forcing during the past glacial/interglacial cycle.
Lo L, Belt S T, Lattaud J, et al. Precession and atmospheric CO 2 modulated variability of sea ice in the central Okhotsk Sea since 130,000 years ago[J]. Earth and Planetary Science Letters, 2018, 488: 36-45.
宋瑞玲 姚锦仙 吴恺悦 张晓川 吕植 朱争光 殷丽洁
宋瑞玲,姚锦仙,吴恺悦,等.海洋保护区管理与保护成效评估的方法与进展[J].生物多样性, 2018, 26(3): 286-294.
Numerical simulation of water entry with improved SPH method
J. R. Shao, Y. Yang, H. F. Gong, M. B. Liu
Water entry problems are very common in engineering and sciences. When objects move with relatively high speed, bubble cavities will be generated, and the behavior of moving objects will also be affected conversely. In this paper, the water entry problems are studied using smoothed particle hydrodynamics (SPH) method, which has special advantages in modeling free surfaces, moving interfaces. First, an improved fluid–solid interface treatment algorithm is presented, whose effectiveness is validated by a water entry of a buoyant cylinder. Then the water entry with different velocities and directions are researched. It is found that the velocities and angles of the moving objects will affect the movement of the object greatly, and the SPH model can give optimal predication of these corresponding conditions.
J. R. Shao, Y. Yang, H. F. Gong, M. B. Liu (2018) Numerical simulation of water entry with improved SPH method. Int. Journal of Computational Methods. 10.1142/S0219876218460040.
Direct measurement of the contact angle of water droplet on quartz in a reservoir rock with atomic force microscopy
Deng, Yajun; Xu, Lei; Lu, Hailong; Wang, Hao; Shi, Yongmin
The wettability of a reservoir rock is an important property affecting the states of fluids in pores that are constructed with minerals of various types. However, the mineral grains are usually micro-sized so that the traditional optical contact angle method is hard to be applied to study their wettabilities. Although some measurements have been carried out for the contact angles of liquids on mineral surfaces, those previous studies were mainly on flat artificial mineral surfaces. To understand the wettabilities of water on rough natural mineral surfaces, the contact angles of micro-sized water droplets on relatively rough quartz surfaces in a natural sand rock were measured with an atomic force microscopy (AFM). The results obtained show that the droplets were asymmetrical so that the contact angles, which were around 27.8–50.3°, were different along the triple-phase contact lines, probably due to surface roughness, heterogeneity, atomic arrangement, etc. As compared with previous studies, surface pretreatment and droplet size were regarded as the two key factors that caused the substantial difference in contact angles of water on quartz between the current and previous researches, which might imply that the present results could better describe the wettability of a natural reservoir rock.
Deng Y, Xu L, Lu H, et al. Direct measurement of the contact angle of water droplet on quartz in a reservoir rock with atomic force microscopy[J]. Chemical Engineering Science, 2018, 177: 445-454.
Ultra-narrow photonic nanojets through a glass cuboid embedded in a dielectric cylinder
Jianming Yang, Patrice Twardowski, Philippe Gérard, Yi Duo, Joël Fontaine, and Sylvain Lecler
A glass cuboid, embedded inside a dielectric cylinder is studied when illuminated with a monochromatic plane wave. A photonic nanojet (PNJ) with a full-width at half-maximum (FWHM) waist of around 0.25λ0 is obtained outside the external surface of the cuboid. The influence of the parameters of a square section cuboid is studied. Three particular phenomena can be obtained and are discussed: an ultra-narrow PNJ on the external surface of the cuboid, a long photonic jet and the excitation of whispering gallery modes (WGMs). A parametric study, over the width and the height of a rectangular section cuboid, shows that these parameters can be used to control the photonic jet properties. We also study several other geometries of the insert, which shows that the key parameter is the refractive index of the inserted material. Finally, we show that by changing the incident angle we can obtain a curved photonic jet.
Yang J, Twardowski P, Gérard P, et al. Ultra-narrow photonic nanojets through a glass cuboid embedded in a dielectric cylinder[J]. Optics express, 2018, 26(4): 3723-3731.
Greatly enhanced anticorrosion of Cu by commensurate graphene coating
Xiaozhi Xu; Ding Yi; Zhichang Wang; Jiachen Yu; Zhihong Zhang; Ruixi Qiao; Zhanghao Sun; Zonghai Hu Peng Gao; Hailin Peng; Zhongfan Liu; Dapeng Yu; Enge Wang; Ying Jiang; Feng Ding; Kaihui Liu
Metal corrosion is a long‐lasting problem in history and ultrahigh anticorrosion is one ultimate pursuit in the metal‐related industry. Graphene, in principle, can be a revolutionary material for anticorrosion due to its excellent impermeability to any molecule or ion (except for protons). However, in real applications, it is found that the metallic graphene forms an electrochemical circuit with the protected metals to accelerate the corrosion once the corrosive fluids leaks into the interface. Therefore, whether graphene can be used as an excellent anticorrosion material is under intense debate now. Here, graphene‐coated Cu is employed to investigate the facet‐dependent anticorrosion of metals. It is demonstrated that as‐grown graphene can protect Cu(111) surface from oxidation in humid air lasting for more than 2.5 years, in sharp contrast with the accelerated oxidation of graphene‐coated Cu(100) surface. Further atomic‐scale characterization and ab initio calculations reveal that the strong interfacial coupling of the commensurate graphene/Cu(111) prevents H2O diffusion into the graphene/Cu(111) interface, but the one‐dimensional wrinkles formed in the incommensurate graphene on Cu(100) can facilitate the H2O diffusion at the interface. This study resolves the contradiction on the anticorrosion capacity of graphene and opens a new opportunity for ultrahigh metal anticorrosion through commensurate graphene coating.
Xu X, Yi D, Wang Z, et al. Greatly enhanced anticorrosion of Cu by commensurate graphene coating[J]. Advanced Materials, 2018, 30(6): 1702944.
Artificial lateral line based local sensing between two adjacent robotic fish
Xingwen Zheng, Chen Wang, Ruifeng Fan and Guangming Xie
The lateral line system (LLS) is a mechanoreceptive organ system with which fish and aquatic amphibians can effectively sense the surrounding flow field. The reverse Kármán vortex street (KVS), known to be a typical thrust-producing wake, is commonly observed in fish-like locomotion and is known to be generated by fish's tails. The vortex street generally reflects the motion information of the fish. A fish can use LLS to detect such vortex streets generated by its neighboring fish, thus sensing its own state and the states of its neighbors in a school of fish. Inspired by this typical biological phenomenon, we design a robotic fish with an onboard artificial lateral line system (ALLS) composed of pressure sensor arrays and use it to detect the reverse KVS-like vortex wake generated by its adjacent robotic fish. Specifically, the vortex wake results in hydrodynamic pressure variations (HPVs) in the flow field. By measuring the HPV using the ALLS and extracting meaningful information from the pressure sensor readings, the oscillating frequency/amplitude/offset of the adjacent robotic fish, the relative vertical distance and the relative yaw/pitch/roll angle between the robotic fish and its neighbor are sensed efficiently. This work investigates the hydrodynamic characteristics of the reverse KVS-like vortex wake using an ALLS. Furthermore, this work demonstrates the effectiveness and practicability of an artificial lateral line in local sensing for adjacent underwater robots, indicating the potential to improve close-range interaction and cooperation within a group of underwater vehicles through the application of ALLSs in the near future.
Zheng X, Wang C, Fan R, et al. Artificial lateral line based local sensing between two adjacent robotic fish[J]. Bioinspiration & biomimetics, 2017, 13(1): 016002.