scholarly journals Phytoplankton and Bacterial Responses to Monsoon-Driven Water Masses Mixing in the Kuroshio Off the East Coast of Taiwan

2021 ◽  
Vol 8 ◽  
Author(s):  
Chao-Chen Lai ◽  
Chau-Ron Wu ◽  
Chia-Ying Chuang ◽  
Jen-Hua Tai ◽  
Kuo-Yuan Lee ◽  
...  
Keyword(s):  
East Coast ◽  
Three Dimensional ◽  
Euphotic Zone ◽  
Kuroshio Current ◽  
Southwest Monsoon ◽  
Three Dimensional Model ◽  
Southern Taiwan ◽  
First Time ◽  
The Kuroshio ◽  
Mixing Water

Biogeochemical responses to mixing were examined in two cruise surveys along a transect across the Kuroshio Current (KC) in May and July 2020. Two stations located at the South China Sea (SCS)–KC mixing and the KC waters were chosen for the diel study. In the euphotic zone (~100 m depth), the average values of nitrate (0.97–1.62 μM), chlorophyll-a (Chl-a, 0.36–0.40 mg/m3), and primary production (PP; 3.46 ± 1.37 mgC/m3/day) of the mixing water station (MWS) of the two cruises were several folds higher than those of the KC station (KCS; nitrate, 0.03–0.10 μM; Chl-a, 0.14–0.24 mg/m3; and PP, 0.91 ± 0.47 mgC/m3/day). In the July cruise, the maximal bacterial production (BP) at the MWS (3.31 mgC/m3/day) was 82% higher in comparison with that of the KCS (1.82 mgC/m3/day); and the readings of Chl-a showed no trend with BP in the oligotrophic KCS, but a positive relationship was found among these measurements at the mesotrophic MWS. This implies that the trophic status of the system might affect phytoplankton–bacteria interactions. The backward-trajectory analyses conducted by an observation-validated three-dimensional model identified that the prevailing southwest monsoon drove a northeastward “intrusion” of the SCS waters in July 2020, resulted in mixing between SCS and Kuroshio (KC) waters off the east coast of southern Taiwan. For the first time, this study demonstrates that the high biological biomass and activities that occur in the KC are induced by the northward intrusion of the SCS waters.

Chemical speciation of iron in the euphotic zone along the Kuroshio Current

2021 ◽  
Vol 233 ◽  
pp. 103966
Author(s):  
Mitsuhide Sato ◽  
Jun Nishioka ◽  
Kazuyuki Maki ◽  
Shigenobu Takeda
Keyword(s):  
Chemical Speciation ◽  
Euphotic Zone ◽  
Kuroshio Current ◽  
The Kuroshio

Problems Associated with the Use of Skirts on Hovercraft

1967 ◽  
Vol 182 (1) ◽  
pp. 201-218
Author(s):  
W. A. Crago
Keyword(s):  
Three Dimensional ◽  
Model Tests ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Operational Conditions ◽  
The Third ◽  
Rough Water ◽  
Delamination Life ◽  
First Time

The lecture commences with a brief description of early hovercraft work and shows how the advent of flexible extensions to the peripheral jets—or ‘skirts’—constituted a breakthrough without which the hovercraft would never have become a practical proposition with the ability to operate over waves and rough ground. It is shown that the introduction of skirts, whilst providing a solution in one respect, also led to a series of problems and three of these are singled out for further discussion. First it is shown that whilst a relatively high internal skirt pressure is desirable to maintain skirt shape under operational conditions, this pressure can also lead to a high rough water drag. The second problem is that of ‘plough in’ and overturning, which is intimately associated with the use of skins. The hydrodynamic mechanisms of both these undesirable phenomena are for the first time explained in detail and are illustrated by means of data obtained from two- and three-dimensional model tests. The third problem raised by the introduction of skirts is skirt oscillation and wear. The techniques necessary to investigate delamination are described and some of the factors which have been shown to be important in increasing delamination life are outlined.

scholarly journals 3D-Analysis of a non-planispiral ammonoid from the Hunsrück Slate: natural or pathological variation?

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3526 ◽  
Author(s):  
Julia Stilkerich ◽  
Trisha A. Smrecak ◽  
Kenneth De Baets
Keyword(s):  
Three Dimensional ◽  
Euphotic Zone ◽  
Type Specimen ◽  
3D Analysis ◽  
Three Dimensional Model ◽  
Hunsrück Slate ◽  
Early Devonian ◽  
Holotype Specimen ◽  
New Type

We herein examine the only known non-planispirally coiled early Devonian ammonoid, the holotype specimen of Ivoites opitzi, to investigate if the host was encrusted in vivo and if these sclerobionts were responsible for the trochospiral coiling observed in this unique specimen. To test if the presence of runner-like sclerobionts infested the historically collected specimen of Ivoites opitzi during its life, we used microCT to produce a three-dimensional model of the surface of the specimen. Our results indicate that sclerobionts grew across the outer rim (venter) on both sides of the ammonoid conch at exactly the location where the deviation from the planispiral was recognized, and where subsequent ammonoid growth would likely preclude encrustation. This indicates in vivo encrustation of the I. opitzi specimen, and represents the earliest documentation of the phenomenon. Further, this suggests that non-planispiral coiling in I. opitzi was likely pathologically induced and does not represent natural morphological variation in the species. Despite the observed anomalies in coiling, the specimen reached adulthood and retains important identifying morphological features, suggesting the ammonoid was minimally impacted by encrustation in life. As such, appointing a new type specimen—as suggested by some authors—for the species is not necessary. In addition, we identify the sclerobionts responsible for modifying the coiling of this specimen as hederelloids, a peculiar group of sclerobionts likely related to phoronids. Hederelloids in the Devonian are commonly found encrusting on fossils collected in moderately deep environments within the photic zone and are rarely documented in dysphotic and aphotic samples. This indicates that when the ammonoid was encrusted it lived within the euphotic zone and supports the latest interpretations of the Hunsrück Slate depositional environment in the Bundenbach-Gemünden area.

Functional expression of theSpodoptera exiguachitinase to examine the virtually screened inhibitor candidates

2019 ◽  
Vol 109 (6) ◽  
pp. 741-751
Author(s):  
L. Zhang ◽  
Z. Guan ◽  
Z. Pan ◽  
H. Ge ◽  
D. Zhou ◽  
...  
Keyword(s):  
Spodoptera Exigua ◽  
Three Dimensional ◽  
Recombinant Baculovirus ◽  
Functional Expression ◽  
Beet Armyworm ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Inhibitor Activity ◽  
New Information ◽  
First Time

AbstractChitinase is responsible for insect chitin hydrolyzation, which is a key process in insect molting and pupation. However, little is known about the chitinase ofSpodoptera exigua(SeChi). In this study, based on theSeChi gene (ADI24346) identified in our laboratory, we constructed the recombinant baculovirus P-Chi for the expression of recombinantSeChi (rSeChi) in Hi5 cells. The rSeChi was purified by chelate affinity chromatography, and the purified protein showed activity comparable with that of a commercialSgChi, suggesting that we harvested activeSeChi for the first time. The purified protein was subsequently tested for enzymatic properties and revealed to exhibit its highest activity at pH 8 and 40 C. Using homology modeling and molecular docking techniques, the three-dimensional model ofSeChi was constructed and screened for inhibitors. In two rounds of screening, twenty compounds were selected. With the purified rSeChi, we tested each of the twenty compounds for inhibitor activity against rSeChi, and seven compounds showed obvious activity. This study provided new information for the chitinase of beet armyworm and for chitinase inhibitor development.

Mechanistic and inhibition studies of chorismate-utilizing enzymes

2005 ◽  
Vol 33 (4) ◽  
pp. 763-766 ◽  
Author(s):  
O. Kerbarh ◽  
E.M.M. Bulloch ◽  
R.J. Payne ◽  
T. Sahr ◽  
F. Rébeillé ◽  
...  
Keyword(s):  
Catalytic Mechanism ◽  
Higher Plants ◽  
Three Dimensional ◽  
Antimicrobial Effect ◽  
Three Dimensional Model ◽  
Antimicrobial Drugs ◽  
Apicomplexan Parasites ◽  
Covalent Intermediate ◽  
Inhibition Studies ◽  
First Time

The shikimate biosynthetic pathway is utilized in algae, higher plants, bacteria, fungi and apicomplexan parasites; it involves seven enzymatic steps in which phosphoenolpyruvate and erythrose 4-phosphate are converted into chorismate. In Escherichia coli, five chorismate-utilizing enzymes catalyse the synthesis of aromatic compounds such as L-phenylalanine, L-tyrosine, L-tryptophan, folate, ubiquinone and siderophores such as yersiniabactin and enterobactin. As mammals do not possess such a biosynthetic system, the enzymes involved in the pathway have aroused considerable interest as potential targets for the development of antimicrobial drugs and herbicides. As an initiative to investigate the mechanism of some of these enzymes, we showed that the antimicrobial effect of (6S)-6-fluoroshikimate is the result of irreversible inhibition of 4-amino-4-deoxychorismate synthase by 2-fluorochorismate. Based on this study, a catalytic mechanism for this enzyme was proposed, in which the residue Lys-274 is involved in the formation of a covalent intermediate. In another study, Yersinia enterocolitica Irp9, which is involved in the biosynthesis of the siderophore yersiniabactin, was for the first time biochemically characterized and shown to catalyse the formation of salicylate from chorismate via isochorismate as a reaction intermediate. A three-dimensional model for this enzyme was constructed that will guide the search for potent inhibitors of salicylate formation, and hence of bacterial iron uptake.

A Three-Dimensional Model of Droplet Impinging, Solidification and Suspension on the Substrate

2011 ◽  
Vol 346 ◽  
pp. 222-227
Author(s):  
Sheng Zhu ◽  
Feng Liang Yin ◽  
Jian Liu ◽  
Yuan Yuan Liang
Keyword(s):  
Surface Tension ◽  
Manufacturing Process ◽  
Three Dimensional ◽  
Metal Droplet ◽  
The Body ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
High Impact Velocity ◽  
The Impact ◽  
First Time

A three-dimensional model was built to study a molten metal droplet impact on an edge of the substrate in droplet deposition manufacturing process for the first time. The whole calculation domain, including the substrate, was described using same fluid conservation equations, which is to say that the remolding and solidification of substrate was considered also. Droplet free surface was tracked by volume-of-fluid (VOF) algorithm. The effect of surface tension on the droplet was taken into consideration by means of considering surface tension to be a component of the body force. The simulated results show that the droplet in liquid phase can keep suspending on the substrate at a role of surface tension. A too high impact velocity would make parts of droplet splash away the substrate which is not allowed in manufacturing process. The offset between edge of droplet and side edge of substrate influences dramatically the impact of the droplet.

scholarly journals Three-dimensional model evaluation of the Ozone Depletion Potentials for n-propyl bromide, trichloroethylene and perchloroethylene

2010 ◽  
Vol 10 (7) ◽  
pp. 17889-17910 ◽  
Author(s):  
D. J. Wuebbles ◽  
K. O. Patten ◽  
D. Wang ◽  
D. Youn ◽  
M. Martínez-Avilés ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Chemistry Transport Model ◽  
Atmospheric Lifetime ◽  
Land Surfaces ◽  
Simplified Modeling ◽  
First Time

Abstract. The existing solvents trichloroethylene (TCE) and perchloroethylene (PCE) and proposed solvent n-propyl bromide (nPB) have atmospheric lifetimes from days to a few months, but contain chlorine or bromine that could affect stratospheric ozone. Several previous studies estimated the Ozone Depletion Potentials (ODPs) for various assumptions for location of nPB emissions, but these studies used simplified modeling treatments. The primary purpose of this study is to reevaluate the ODP for nPB using a current-generation chemistry-transport model of the troposphere and stratosphere. For the first time, ODPs for TCE and PCE are also evaluated. Emissions representing industrial use of each compound are incorporated on land surfaces from 30° N to 60° N. The atmospheric chemical lifetime obtained for nPB is 24.7 days, similar to past literature, but the ODP is 0.0049, lower than in past studies. The derived atmospheric lifetime for TCE is 13.0 days and for PCE is 111 days. The corresponding ODPs are 0.00035 and 0.0060, respectively.

scholarly journals Intraseasonal Variability of the Kuroshio at 18°N Observed by Mooring Array in 2018-2020

2021 ◽  
Author(s):  
Xin Yuan ◽  
Qingye Wang ◽  
Jie Ma ◽  
Shijian Hu ◽  
Dunxin Hu
Keyword(s):  
Current Velocity ◽  
Intraseasonal Variability ◽  
Propagation Speed ◽  
Kuroshio Current ◽  
Volume Transport ◽  
Direct Measurements ◽  
First Time ◽  
The Kuroshio ◽  
Kuroshio Transport

Abstract Based on direct measurements of the Kuroshio current velocity at 18°N by an array of three moorings from January 2018 to February 2020, the intraseasonal variability (ISV) of the Kuroshio and possible dynamic mechanism are studied. The Kuroshio transport in the upper 350m between 122.7°E and 123.3°E is estimated to be 6.5 Sv ± 2.6 Sv. It is revealed for the first time that both the current velocity and volume transport the Kuroshio at 18°N have a significant 50-60-day ISV, which contributes to over 30% of the total variance. Further analysis indicates the ISV of the Kuroshio is caused by the westward propagating eddies with a wavelength of about 633 km and a propagation speed of about 13 cm/s. In addition, the transport mode (74.2%) of the Kuroshio at 18°N is dominant, rather than the migration mode (11.6%). That is different from the Kuroshio east of Taiwan. The findings of this study will highlight the important role of westward Rossby waves (eddies) with a finite wavelength in modulating the intraseasonal variability of the Kuroshio transport near its origin.

scholarly journals Phytoplankton productivity and rapid trophic transfer to microzooplankton stimulated by turbulent nitrate flux in oligotrophic Kuroshio Current

2019 ◽  
Author(s):  
Toru Kobari ◽  
Taiga Honma ◽  
Daisuke Hasegawa ◽  
Naoki Yoshie ◽  
Eisuke Tsutumi ◽  
...  
Keyword(s):  
Turbulent Mixing ◽  
Euphotic Zone ◽  
Kuroshio Current ◽  
Biological Productivity ◽  
Phytoplankton Productivity ◽  
Kuroshio Front ◽  
Dilution Experiments ◽  
Nitrate Flux ◽  
Enrichment Experiments ◽  
The Kuroshio

Abstract. The Kuroshio Current has been thought to be biologically unproductive due to oligotrophic conditions and low plankton standing stocks. Nevertheless, major foraging fishes are known to grow and recruit around the Kuroshio Current. While mixing and advection supplying nutrients to the euphotic zone are happened by eddies and meanders but limited at the Kuroshio front, there is a risk that survival of vulnerable life stages is encountered under the low food availability. Here we report that phytoplankton productivity is stimulated by turbulent nitrate flux amplified with the Kuroshio Current and rapidly transferred to microzooplankton through their grazing. Oceanographic observations demonstrate that the Kuroshio Current topographically enhances significant turbulent mixing and nitrate influx to the euphotic zone. Gradual nutrient enrichment experiments show growth rates of phytoplankton and microzooplankton communities stimulated within a range of the turbulent nitrate flux. Dilution experiments imply a significant microzooplankton grazing on phytoplankton. We propose that these rapid and systematic trophodynamics enhance invisible biological productivity in the Kuroshio.

scholarly journals 3D-Analysis of a non-planispiral ammonoid from the Hunsrück Slate: natural or pathological variation?

2016 ◽  
Author(s):  
Julia Stilkerich ◽  
Trisha A Smrecak ◽  
Kenneth De Baets
Keyword(s):  
Three Dimensional ◽  
Euphotic Zone ◽  
Type Specimen ◽  
3D Analysis ◽  
Three Dimensional Model ◽  
Hunsrück Slate ◽  
Early Devonian ◽  
Holotype Specimen ◽  
New Type

We herein examine the only known non-planispirally coiled early Devonian ammonoid, the holotype specimen of Ivoites opitzi, to investigate if the host was encrusted in vivo and if these sclerobionts were responsible for the trochospiral coiling observed on this unique specimen. To test if the presence of runner-like sclerobionts infested the historically collected specimen of Ivoites opitzi during its life, we used microCT to produce a three-dimensional model of the surface of the specimen. Our results indicate that sclerobionts grew across the outer rim (venter) on both sides of the ammonoid conch at exactly the location where the deviation from the planispiral was recognized, and where subsequent ammonoid growth would likely preclude encrustation. This indicates in vivo encrustation of the I. opitzi specimen, and represents the earliest documentation of the phenomenon. Further, this suggests that non-planispiral coiling in I. opitzi was pathologically induced and does not represent natural morphological variation in the species. Despite the observed anomalies in coiling, the specimen reached adulthood and retains important identifying morphological features, suggesting the ammonoid was minimally impacted by encrustation in life. As such, appointing a new type specimen – as suggested by some authors – for the species is not necessary. In addition, we identify the sclerobionts responsible for modifying the coiling of this specimen as hederelloids, a peculiar group of sclerobionts likely related to phoronids. Hederelloids in the Devonian are commonly found encrusting on fossils collected in moderately deep environments within the photic zone and are rarely documented in dysphotic and aphotic samples. This indicates that when the ammonoid was encrusted it lived within the euphotic zone and supports the latest interpretations of the Hunsrück Slate depositional environment.

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