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hello i'm suns kenosaki

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a master student at lc tokyo tech

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it is a great honor to be able to speak

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to you today

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i'd like to thank the organizers for

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choosing my abstract

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for live streaming today i'll give you a

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presentation of the results of high

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pressure viscosity measurements

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of mgsl4 solutions which is one of the

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possible compositions

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of the subsurface ocean of isis

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satellites

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and some implications for these

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environments

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and habitability first

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i would like to introduce icy satellites

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ic satellites are the major type of

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satellites of outer solar system planets

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and composed mainly of ice and rocks

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with the research progress it has become

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highly probable that

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some big isis attracts such as ganymede

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europa and titan have an ocean

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of liquid water underneath the thick ice

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crust covering the surface

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understanding this ocean environment is

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an important topic

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because it can lead to discussions on

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the diversity

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material cycle evolution

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what is the ocean environment like this

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figure is the pressure and temperature

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phase diagram of pure water

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markers on the vertical axis indicates

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the pressure of the boundary

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between the hydrosphere hydrosphere and

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the rocky layer

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of each body earth europa

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titan and climate as you can see here

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the ocean on these icy satellites has a

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larger

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maximum pressure than the earth's ocean

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and reaches one giga pascal in some

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satellite

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the assumed pressure temperature

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condition inside the icy satellites are

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shaded in blue

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and conditions of the ocean are shaded

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in that

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it should be noted that the actual ocean

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contains a variety of salt

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which lower the melting point somewhat

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and broadened the condition of the ocean

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the composition of the ocean has been

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discussed

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from various viewpoints such as surface

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composition

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in this study we focus on mgso4

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magnesium sulfate

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as one of the possible compositions for

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more

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accurate view of the ocean environment

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it is essential to understand

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how the ocean fluid behaves and the low

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temperature

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here i will focus on viscosity as one of

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the essential properties of the fluid

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this property determines material

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transport by diffusion

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and how fluid moves viscosity

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is dependent on pressure temperature and

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composition

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the figure shows the change in viscosity

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by adding various salt to water

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where the horizontal axis is the

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concentration

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and the vertical axis is the relative

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viscosity

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to water in particular

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the effect of mgs cell 4 on viscosity

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is very large in other words

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if the subsurface ocean contains a lot

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of mgso4

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the viscosity of the ocean fluid may be

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completely different from the pure water

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ocean

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however the there are no viscosity data

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under the temperature and pressure

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therefore this study aims to determine

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the temperature under pressure

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dependence of viscosity

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of aggregate mgso4 solutions at low

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temperature and high temp high pressure

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which can be applied to icy satellites

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in this study the viscosity of a 10

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weight percent acquires mgso for

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solution

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in these conditions

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was measured by the following sphere

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method using a diamond ambient cell

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a high pressure generator as shown here

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the temperature was controlled

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controlled by throwing hot

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and cold water through the dark and

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the pressure was determined using the

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the principle of the following sphere

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method is simple

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this method obtains a fluid viscosity by

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measuring the

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velocity of a falling sphere through the

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fluid

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this working equation is derived by

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considering the balance

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of gravity variancy and viscous

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resistance

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on the falling sphere and device

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collection factor

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a is the radius of the sphere

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rho is the density of the sphere and

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fluid

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respectively and g

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is the gravitational acceleration

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to acquire the velocity of the falling

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sphere in the dark

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i constructed this system this is a

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simplified image of the system and this

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is a

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picture of the dark diamond angle cell

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used in the experiment

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and a photo inside the cell

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the diamond army cell is mounted on a

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rotating stage

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and each rotation of the stage brings

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the sphere from the bottom

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to the top of the sample chamber

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then it can be dropped using

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light microscope and camera

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i monitored and recorded the drop motion

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then i measured the velocity of the

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sphere and calculated the viscosity

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let's move on to the result the plot

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on the left figure show the experimental

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results

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viscosity of magnesium sulfate solution

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at

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reference

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the viscosity value acquired ranged from

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1 to 10 meter pascal seconds

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on the right figure the viscosity of

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pure water is shown as a dashed line

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for comparison and the viscosity of

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various aqueous electro

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light solutions by reference is shown

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as a dotted line as with the viscosity

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of

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other accuracy mgso aqueous electrolyte

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solutions

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the pressure dependence of the viscosity

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of magnesium sulfate solution

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can be fitted by the quadratic equation

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shown

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by the solid line at all temperatures

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the viscosity of magnesium sulfate

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solution is

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using the pressure and temperature

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dependence of viscosity

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of the end in this study i calculated

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the viscosity

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at a given temperature and pressure i

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draw

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iso viscosity lines on the phase diagram

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of 10 weight percent magnesium sulphate

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solution

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the shaded area represents the

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temperature and pressure range of the

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while the viscosity of pure water ocean

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shown in the right figure is around

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1 or 2 meter pascal seconds the ocean of

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10 weight percent mgso4 solutions

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can vary from 1 to 10 mega pascal

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seconds

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one digit valuation depending on the

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i showed that viscosity of subsurface

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ocean fluid may be

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highly variable one digit in the case of

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10 weight percent of energy software

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solutions

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so i will introduce some implications

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for iso satellites

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this is the simplified cross-sectional

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installation

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of isosatellites with some possible

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phenomena

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related to viscosity and habitability

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viscosity relates to how ocean fluid

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moves

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it affects the convection style of the

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subsurface ocean

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and fluid movement velocity

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through rocks and ices

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therefore the time scale of

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differentiation of these bodies and

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photo saturation

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from an astrobiological point of view

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diffusion is one of the important

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keywords related to viscosity

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the diffusion coefficient in the

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solution can be

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written as the stocks einstein equation

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which says the diffusion coefficient is

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inversely proportional to the viscosity

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therefore viscosity variation affects

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the

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efficiency of material transport by

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diffusion

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the right process

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such as nutrient transportation

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let's move on to the protein as you know

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proteins are large molecules and are

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composed

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of long chains of amino acid

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in a solution proteins have

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variable structures in proteins

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processes such as folding and catalysis

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slowed by solution viscosity around the

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protein

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now let me touch on the implication

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based on the study of the prebiotic

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chemistry on the earth

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when a double strand like dna diffuses

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apart

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high viscosity makes it difficult for

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these strands to

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rebind again allowing small

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oligonucleotides

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to bind each strand for replication

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although this study assumes much higher

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solvent viscosity than measured in my

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study

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and its discussion includes temperature

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increase and

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decreasing degree cycle this has an

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implication for the

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possible biologic process under the high

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viscosity condition

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in summary viscosity variation

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of the subsurface ocean fluid one digit

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in the case of thin weight-based mgso4

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solutions

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occur due to pressure temperature and

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concentration change

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which might affect convection

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differentiation