0:00
welcome to our comprehensive guide on
0:02
simple diffusion In this video we'll
0:04
explore what simple diffusion is how it
0:07
works and why it's important Simple
0:09
diffusion is a fundamental transport
0:11
mechanism where molecules move from
0:13
areas of high concentration to areas of
0:18
concentration When barriers are removed
0:20
molecules naturally spread out from
0:22
areas of high concentration to areas of
0:24
low concentration until equilibrium is
0:27
reached This simple process occurs
0:29
throughout nature and has numerous
0:31
applications in science medicine and
0:34
industry To understand simple diffusion
0:36
remember these key concepts It moves
0:38
substances from high to low
0:40
concentration requires no energy is
0:42
driven by random molecular motion and is
0:44
essential for many biological processes
0:47
Throughout this series we'll explore the
0:49
mechanisms factors and applications of
0:51
diffusion in greater detail
0:55
Now let's take a closer look at the
0:57
precise definition of simple diffusion
1:00
Simple diffusion is a type of passive
1:02
transport where molecules move across
1:04
permeable barriers based on
1:06
electrochemical potential
1:09
differences It involves the movement of
1:11
solutes from areas of high concentration
1:14
to areas of low concentration This
1:16
process requires no energy input unlike
1:18
active transport mechanisms that consume
1:21
ATP The diffusion process continues
1:23
until the concentration equalizes
1:25
throughout the available space reaching
1:29
state Brownian motion is the random
1:32
erratic movement of particles suspended
1:34
in a fluid This phenomenon first
1:36
observed by botist Robert Brown in 1827
1:40
results from particles being bombarded
1:42
by the surrounding mediums molecules
1:45
Let's visualize this process here The
1:47
orange particles represent suspended
1:49
particles while the tiny blue dots
1:52
represent the fluid molecules The
1:54
suspended particles move erratically as
1:56
they're constantly bombarded by the
1:58
fluid molecules from all directions
2:00
These random movements have a powerful
2:02
cumulative effect Over time they cause
2:05
particles to spread evenly throughout
2:07
the available space This is why
2:10
particles naturally move from areas of
2:12
high concentration to areas of low
2:14
concentration even though individual
2:16
particle movements are
2:18
random Although each particle moves
2:20
randomly due to molecular collisions the
2:22
overall statistical tendency is for them
2:25
to distribute evenly The key takeaway is
2:28
that the randomness of molecular
2:30
collisions is the driving force behind
2:32
simple diffusion a fundamental process
2:34
in chemistry and biology
2:39
TRL's formula provides a mathematical
2:41
description of diffusion The formula can
2:44
be simplified to J= M * delta C * F
2:47
where J represents the flux or flow rate
2:50
of particles M represents mobility which
2:53
describes how easily particles can move
2:55
through a medium Delta C represents the
2:58
concentration gradient which is the
3:00
difference in concentration between two
3:03
F represents external driving forces
3:06
such as pressure temperature or electric
3:09
fields Let's visualize each component
3:11
Starting with mobility particles with
3:13
higher mobility move quickly and spread
3:16
out faster than those with lower
3:19
mobility The concentration gradient is
3:22
the difference in concentration between
3:24
two regions Particles naturally move
3:27
from regions of high concentration to
3:29
regions of low concentration
3:32
driving forces can accelerate or inhibit
3:34
diffusion beyond what would occur from
3:36
concentration differences
3:39
alone Let's look at a practical example
3:42
of how TRL's formula helps predict
3:48
rates In summary TRL's formula provides
3:52
a powerful tool for predicting and
3:54
understanding diffusion rates in
3:55
biological systems and industrial
4:00
Diffusion is a continuous process that
4:02
proceeds until it reaches a state called
4:06
equilibrium Equilibrium is reached when
4:08
the concentration of molecules become
4:11
uniform throughout the system When
4:13
allowed to diffuse freely molecules move
4:16
from areas of high concentration to
4:21
concentration As diffusion continues we
4:24
eventually reach equilibrium where
4:25
molecules are evenly distributed
4:31
At equilibrium although molecules
4:33
continue to move randomly due to
4:35
Brownian motion there is no net movement
4:41
direction This state of equilibrium
4:43
represents the maximum entropy or
4:45
disorder of the system It is the most
4:48
energetically stable state While
4:50
molecules continue to move in all
4:52
directions the rates of movement between
4:54
any two areas are equal resulting in
5:00
flux Remember that equilibrium doesn't
5:03
mean molecules stop moving It simply
5:05
means there is no net directional
5:07
movement The system has reached its most
5:12
state The concentration gradient is the
5:15
difference in concentration between two
5:17
regions Here we can see a container with
5:20
a high concentration of molecules on the
5:22
left and a low concentration on the
5:24
right The difference in concentration
5:27
between these two regions creates a
5:29
concentration gradient that drives
5:32
diffusion The steeper the concentration
5:35
gradient the faster diffusion
5:37
occurs Notice how molecules move much
5:40
faster from high to low concentration
5:42
when the gradient is steeper
5:45
As molecules move from high to low
5:47
concentration areas the gradient
5:49
gradually decreases until it reaches
5:53
equilibrium This concentration gradient
5:56
is the primary driving force behind
5:58
simple diffusion Without a gradient
6:07
diffuse Smaller molecules diffuse faster
6:10
than larger ones because they encounter
6:12
less resistance when moving through a
6:14
medium This is because smaller molecules
6:17
have less surface area and therefore
6:19
experience less drag when moving through
6:23
medium When molecules move through a
6:25
medium they encounter resistance from
6:27
surrounding particles and
6:29
structures Smaller molecules can
6:32
navigate between these obstacles facing
6:34
less resistance Larger molecules however
6:38
have more difficulty navigating through
6:39
the same space and encounter more
6:44
This relationship between molecular size
6:46
and diffusion rate is described by
6:48
Graham's law of diffusion According to
6:51
Graham's law the rate of diffusion of a
6:53
gas is inversely proportional to the
6:55
square root of its molecular mass
7:01
diffuse much more rapidly than larger
7:03
molecules like proteins For example
7:06
oxygen with a molecular mass of 32 dtons
7:09
diffuses about 45 times faster than
7:11
hemoglobin with a mass of 64,500 dolton
7:15
This relationship between molecular size
7:17
and diffusion rate is crucial in
7:19
biological systems affecting everything
7:22
from cellular respiration to drug
7:26
Understanding how molecular size affects
7:28
diffusion helps us explain many natural
7:31
processes and design more effective
7:34
technologies Temperature plays a
7:36
critical role in diffusion processes by
7:38
directly influencing molecular kinetic
7:41
energy Let's observe how temperature
7:44
affects molecular motion At lower
7:46
temperatures molecules move slowly with
7:48
less kinetic energy In colder
7:51
environments molecules have less energy
7:53
and move slower resulting in slower
7:55
diffusion rates In contrast at higher
7:58
temperatures molecules have more kinetic
8:00
energy moving much faster As you can see
8:03
the higher temperature causes
8:05
significantly faster molecular movement
8:07
which directly accelerates the diffusion
8:11
process This relationship can be
8:13
described mathematically The diffusion
8:15
coefficient is directly proportional to
8:17
temperature as shown in the Stokes
8:19
Einstein equation As temperature
8:22
increases the diffusion coefficient
8:25
linearly Temperature- dependent
8:27
diffusion is observed in many natural
8:30
and industrial settings In natural
8:32
systems such as living organisms cell
8:35
membranes become more permeable at
8:37
higher temperatures allowing for faster
8:39
diffusion of molecules into and out of
8:41
cells In industrial settings many
8:44
processes like chemical reactions and
8:46
material manufacturing are carefully
8:48
temperature controlled to optimize
8:53
efficiency To summarize temperature
8:55
directly impacts diffusion rates Higher
8:58
temperatures provide molecules with more
9:00
kinetic energy resulting in faster
9:03
molecular motion and therefore faster
9:05
diffusion This fundamental relationship
9:08
makes diffusion processes highly
9:10
temperature dependent
9:13
Solubility and its impact on diffusion
9:16
Solubility refers to how readily a
9:18
substance dissolves in a particular
9:20
solvent Molecules that are more soluble
9:22
in a membrane can diffuse through it
9:26
easily Cell membranes consist of a
9:29
phospholipid blayer which has both
9:31
hydrophobic and hydrophilic regions
9:33
Let's examine how different types of
9:35
molecules interact with the cell
9:37
membrane Lipid soluble molecules can
9:39
easily pass through the cell membrane
9:41
because they can dissolve in the
9:45
billayer In contrast water- soluble
9:47
molecules struggle to pass through the
9:50
hydrophobic regions of the
9:52
membrane This principle of solubility
9:54
has important applications in drug
9:56
design Many medications are designed to
9:59
be lipid soluble to improve their
10:01
ability to cross cell membranes and
10:04
reach their targets inside cells
10:06
Examples of lipid-soluble drugs include
10:08
aspirin steroids and various
10:11
anesthetics Let's summarize how
10:13
solubility impacts diffusion across cell
10:16
membranes Substances with high membrane
10:18
solubility diffuse quickly and easily
10:20
through membranes This includes oxygen
10:23
carbon dioxide and many hormones In
10:26
contrast substances with low membrane
10:28
solubility like ions and glucose diffuse
10:31
slowly and require specialized transport
10:33
proteins to cross membranes efficiently
10:36
Understanding solubility is crucial for
10:38
predicting how molecules will move
10:40
across biological membranes which has
10:43
significant implications in physiology
10:47
biotechnology The density of the solvent
10:50
medium significantly affects how
10:52
molecules move through it during
10:53
diffusion Diffusion occurs at different
10:56
rates depending on the state of matter
10:59
Let's examine how molecules move in gas
11:01
liquid and solid environments In gases
11:04
with low density molecules move rapidly
11:07
with minimal resistance resulting in
11:09
fast diffusion In liquids with medium
11:11
density molecules encounter more
11:13
resistance slowing their movement and
11:16
reducing diffusion speed In solids with
11:18
high density molecules face significant
11:21
resistance greatly limiting their
11:23
movement and resulting in very slow
11:25
diffusion The key concept is that denser
11:27
solvents create more resistance which
11:29
leads to slower diffusion rates This
11:32
principle is critical in many industrial
11:36
applications For example pharmaceutical
11:38
companies carefully select solvent
11:40
densities to control how quickly
11:42
medications release their active
11:44
ingredients Understanding solvent
11:46
density effects allows scientists and
11:48
engineers to control diffusion rates in
11:50
various applications from drug delivery
11:53
systems to industrial manufacturing
11:57
processes Surface area and membrane
11:59
thickness are critical factors that
12:01
directly influence diffusion rates
12:04
Larger surface areas allow more
12:06
molecules to diffuse simultaneously
12:08
significantly increasing the overall
12:10
rate of diffusion Consider these two
12:13
containers one narrow with a small
12:15
surface area and one wide with a large
12:17
surface area With three times the
12:19
surface area the wider container allows
12:21
more molecules to diffuse simultaneously
12:24
resulting in a much higher overall
12:27
rate Conversely membrane thickness has
12:30
an opposite effect on diffusion Thicker
12:32
membranes slow diffusion by increasing
12:34
the distance molecules must travel to
12:36
get from one side to the other
12:39
Notice how particles move through the
12:41
thin membrane more quickly than the
12:43
thick membrane where they encounter
12:47
resistance This is why many biological
12:49
structures have evolved to maximize
12:51
surface area through folding or
12:53
branching while minimizing membrane
12:55
thickness In the lungs tiny air sacks
12:58
called alvoli create an enormous surface
13:01
area for gas exchange The human lungs
13:04
contain about 500 million alvoli
13:06
providing a surface area of around 70
13:09
square meters Similarly the small
13:11
intestine uses finger-like projections
13:13
called villi to dramatically increase
13:15
the surface area available for nutrient
13:17
absorption This adaptation increases the
13:20
functional surface area by up to 600
13:23
times Remember that surface area and
13:26
membrane thickness work together to
13:28
determine how efficiently diffusion
13:30
occurs in both natural and engineered
13:33
systems These principles guide the
13:35
design of structures where diffusion is
13:40
critical Bacteria rely heavily on simple
13:43
diffusion for acquiring nutrients from
13:45
their environment Unlike more complex
13:47
organisms bacteria lack sophisticated
13:50
transport systems and must instead
13:52
depend on nutrients passively diffusing
13:54
across their cell membranes This
13:57
reliance on simple diffusion creates a
13:59
fundamental limitation on bacterial size
14:02
A small bacterium has a higher surface
14:04
area to volume ratio allowing more
14:06
efficient nutrient diffusion relative to
14:08
its size In contrast a large bacterium
14:12
has a lower surface area to volume ratio
14:15
which limits how efficiently nutrients
14:17
can reach its interior through diffusion
14:19
alone This is why bacterial size is
14:21
naturally limited They must maintain a
14:24
high surface area to volume ratio to
14:26
ensure adequate diffusion of nutrients
14:28
in and waste products
14:32
out Pharmaceutical companies carefully
14:35
design medications with diffusion
14:37
principles in mind After administration
14:40
drugs enter the bloodstream and must
14:42
diffuse across various barriers to reach
14:44
their target tissues The rate of
14:47
diffusion is critical It determines how
14:49
quickly a medication takes effect and
14:52
how long it remains active in the
14:55
body Several key factors affect how
14:57
drugs diffuse through the body Molecular
14:59
size solubility concentration gradient
15:05
Understanding diffusion principles helps
15:07
pharmaceutical companies develop
15:08
different drug delivery
15:11
systems Immediate release formulations
15:13
deliver the full dose of medication at
15:15
once causing a rapid increase in drug
15:18
concentration Controlled release
15:20
formulations on the other hand use
15:22
special matrices or codings to release
15:24
medication gradually over
15:27
time This graph compares how drug
15:30
concentration changes over time with
15:32
different formulations Immediate release
15:34
formulations quickly reach peak
15:36
concentration but may fall below
15:39
therapeutic levels rapidly Controlled
15:41
release formulations maintain drug
15:43
levels within the therapeutic range for
15:45
a longer period improving effectiveness
15:48
and reducing side effects By
15:50
understanding and applying diffusion
15:52
principles pharmaceutical scientists can
15:54
design medications that maintain
15:56
therapeutic drug levels over extended
15:59
periods improving patient outcomes
16:04
Environmental scientists study air
16:06
pollution dispersal to understand how
16:08
pollutants spread through the atmosphere
16:11
When pollutants are released from
16:12
sources like factories they spread
16:14
through diffusion from areas of high
16:16
concentration to areas of lower
16:19
concentration This natural process is
16:22
driven by random molecular motion
16:24
causing particles to gradually spread
16:26
away from the source
16:29
As pollutants disperse they create a
16:31
concentration gradient The concentration
16:33
is highest near the source and decreases
16:36
with distance Several factors influence
16:39
how pollutants disperse through the air
16:41
Temperature affects the rate of
16:43
dispersal Higher temperatures increase
16:45
the kinetic energy of particles causing
16:48
faster and more extensive diffusion Wind
16:51
plays a crucial role by accelerating the
16:53
dispersal process and determining the
16:56
direction of pollution spread The
16:58
pattern and extent of pollution
16:59
dispersal determines its environmental
17:02
impact This includes effects on air
17:04
quality in surrounding areas deposition
17:07
of pollutants on land and water bodies
17:09
and exposure risks for ecosystems and
17:12
human populations Understanding how
17:14
pollutants disperse through diffusion is
17:16
essential for developing effective
17:18
environmental protection strategies and
17:24
Diffusion plays a crucial role in
17:26
metallergy the science of metal
17:30
processing An alloy is a mixture of
17:32
multiple metals or a metal with other
17:36
elements When different metals are
17:38
heated together atoms from each metal
17:40
begin to move rapidly through diffusion
17:43
Atoms from each metal migrate across the
17:46
boundary into the other metal
17:49
At the interface atoms mix together
17:52
creating an alloy with properties
17:53
different from either original
17:58
metal This process diffusion bonding
18:01
joins materials by atomic diffusion when
18:04
heated under pressure without melting
18:07
metals Alloys often exhibit enhanced
18:10
properties compared to their constituent
18:12
metals such as increased hardness
18:14
strength and better corrosion resistance
18:19
Diffusion created alloys are crucial in
18:22
manufacturing everything from jewelry to
18:24
aerospace components electronics and
18:28
materials Metal alloy formation through
18:31
diffusion demonstrates how nature's
18:33
simple principles enable advanced
18:37
science Let's compare passive transport
18:40
like simple diffusion with active
18:42
transport In passive transport molecules
18:45
move across a membrane with no energy
18:47
input This relies solely on the kinetic
18:49
energy of the molecules and follows the
18:52
concentration gradient from high to low
18:55
concentration Active transport however
18:57
requires energy input in the form of ATP
19:00
This energy allows molecules to be
19:02
transported against their concentration
19:04
gradient from low to high
19:07
concentration Let's examine the key
19:10
differences between these transport
19:16
While passive transport like simple
19:18
diffusion is energy efficient it is
19:20
limited to moving molecules from areas
19:22
of high concentration to low
19:25
concentration Active transport can work
19:28
against concentration gradients but
19:30
requires ATP energy making it less
19:32
energy efficient Both transport
19:34
mechanisms play essential roles in
19:36
cellular function with simple diffusion
19:39
providing energyefficient transport
19:44
gradients Simple diffusion is unique
19:47
because it doesn't require the help of
19:49
membrane proteins At the heart of this
19:52
concept is the phospholipid billayer of
19:54
cell membranes Simple diffusion involves
19:57
the direct movement of molecules through
19:59
the phospholipid blayer without any
20:02
assistance Small uncharged molecules can
20:05
pass directly through the lipid portion
20:07
of the membrane moving from areas of
20:09
high concentration to areas of low
20:13
concentration Let's compare simple
20:15
diffusion with facilitated diffusion to
20:17
understand the key differences Simple
20:20
diffusion occurs directly through the
20:22
phosphoipid blayer while facilitated
20:24
diffusion requires transport proteins
20:26
embedded in the membrane In simple
20:29
diffusion small molecules like oxygen
20:31
and carbon dioxide move directly through
20:35
billayer In contrast facilitated
20:37
diffusion requires specific transport
20:39
proteins to help larger or charged
20:43
membrane Let's highlight the key
20:46
distinctions that make simple diffusion
20:48
unique Simple diffusion doesn't require
20:50
any transport It works best for small
20:53
uncharged molecules like oxygen and
20:56
carbon dioxide Like all diffusion
20:58
processes it follows concentration
21:00
gradients from high to low Its rate is
21:03
limited by factors like molecular size
21:07
properties Let's look at some common
21:09
examples of molecules that use simple
21:12
diffusion to cross cell membranes Oxygen
21:15
and carbon dioxide are classic examples
21:17
of molecules that use simple diffusion
21:19
to cross cell membranes Water also uses
21:22
simple diffusion though it's primarily
21:24
regulated by osmosis Other small lipid
21:27
soluble molecules can diffuse directly
21:29
through the membrane as
21:31
well To summarize simple diffusion is a
21:36
passive transport process that allows
21:38
molecules to move directly through the
21:40
phospholipid blayer without the
21:42
assistance of membrane proteins This
21:44
independence from membrane proteins
21:46
distinguishes simple diffusion from
21:48
facilitated diffusion though both follow
21:53
gradients Scientists use various
21:56
techniques to measure diffusion rates in
21:58
different systems Three primary
22:00
techniques include fluorescent markers
22:02
which allow tracking of labeled
22:04
molecules through fluorescent microscopy
22:07
radioactive tracers which use isotopes
22:09
to monitor molecule movement across
22:12
membranes and tissues and specialized
22:14
imaging methods such as FRAP fret and
22:16
other advanced techniques that capture
22:18
diffusion in real time Fix laws of
22:22
diffusion provide the mathematical
22:24
framework for understanding and
22:25
measuring diffusion rates
22:28
Fix first law states that the diffusion
22:30
flux is proportional to the
22:32
concentration gradient This helps
22:34
calculate the amount of substance
22:36
flowing through a unit area per unit
22:38
time Fix second law describes how
22:41
concentration changes over time which is
22:44
proportional to the second derivative of
22:46
concentration with respect to position
22:49
These equations include variables for
22:50
diffusion flux the diffusion coefficient
22:53
concentration position and time
22:57
These measurement techniques and
22:58
mathematical models help scientists
23:00
understand and quantify diffusion in
23:03
various practical applications In
23:05
biology diffusion rate measurements help
23:08
understand nutrient transport across
23:11
tissues Industrial engineers use
23:13
diffusion measurements to optimize
23:15
equipment design for gas exchange mixing
23:18
processes and material development In
23:21
pharmaceutical research diffusion rate
23:23
measurements are crucial for determining
23:26
drug release rates from delivery systems
23:28
and predicting drug distribution in the
23:31
body Let's examine a common technique
23:34
called fluorescent recovery after
23:35
photobleaching or FRAP In this technique
23:39
a small region containing fluorescent
23:41
molecules is exposed to intense light
23:43
causing photobleaching As time passes
23:46
unbleached fluorescent molecules from
23:48
surrounding areas diffuse into the
23:51
bleached region The rate of fluorescent
23:53
recovery directly correlates with the
23:55
diffusion rate allowing scientists to
23:57
calculate precise diffusion
24:00
coefficients To summarize scientists use
24:03
various techniques to measure diffusion
24:05
rates with fixed laws providing the
24:07
mathematical foundation for these
24:09
measurements These measurements help
24:11
researchers understand biological
24:14
processes design industrial equipment
24:17
and develop pharmaceutical products with
24:20
precision Plants rely on diffusion for
24:23
nutrient uptake from the soil Let's
24:25
examine how this critical process works
24:27
The root system of plants especially the
24:30
tiny root hairs provides an extensive
24:32
surface area for nutrient absorption
24:35
Essential nutrients like nitrogen
24:37
phosphorus potassium and water are
24:39
present in the soil at various
24:41
concentrations These nutrients diffuse
24:43
from areas of high concentration in the
24:45
soil to areas of lower concentration
24:48
inside the root hairs following
24:50
concentration gradients
25:17
Plants use two main mechanisms for
25:19
nutrient uptake Passive diffusion occurs
25:21
naturally requiring no energy from the
25:24
plant However for some essential
25:26
nutrients especially when soil
25:28
concentrations are low plants must use
25:30
active transport which requires energy
25:33
Understanding diffusion in plant
25:35
nutrition has led to several important
25:37
agricultural practices that enhance crop
25:39
yields By optimizing conditions for
25:42
diffusion farmers can significantly
25:44
improve nutrient uptake efficiency and
25:46
ultimately increase crop
25:50
yields Diffusion principles have
25:52
applications far beyond natural
25:54
processes forming the basis for numerous
25:57
technological innovations
25:59
Dialysis machines rely on diffusion to
26:02
filter waste products from blood As
26:04
blood flows through the dializer waste
26:06
molecules diffuse across a
26:08
semi-permeable membrane due to
26:12
differences Controlled release
26:14
fertilizers utilize diffusion principles
26:16
to gradually deliver nutrients to plants
26:19
A polymer coating controls the rate at
26:21
which nutrients diffuse into the soil
26:24
providing sustained nutrition
26:27
Gas sensors detect chemicals based on
26:29
their diffusion properties Target gas
26:32
molecules diffuse through a selective
26:33
membrane at specific rates enabling
26:36
precise detection of compounds like
26:40
methane Understanding diffusion
26:42
principles has led to numerous practical
26:45
innovations across multiple industries
26:48
From pharmaceutical delivery systems to
26:50
water purification membranes diffusion
26:52
science continues to drive technological
26:58
Simple diffusion is a fundamental
27:01
process that occurs throughout nature It
27:03
has countless applications across many
27:06
disciplines from science and medicine to
27:08
industry and technology What makes
27:10
diffusion so important is that it occurs
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naturally without energy expenditure
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driven by concentration gradients and
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influenced by factors like temperature
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Understanding this basic principle helps
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us develop more effective medications
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innovative technologies and sustainable
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solutions to various challenges In
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conclusion simple diffusion shapes our
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world in ways both visible and invisible
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underlying countless processes essential
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to life and technology