hello everyone
so if you've taken a plane, perhaps
a little bit less this year, you will all
be familiar with the sign that says
prepare for security, leave your liquids
and it also says gels creams pastes
and all sorts of other things so what
i'm going to tell you about today
is what all the stuff that you leave in
the box
at security have in common
and it's not going to be so much about
the liquids
but the rest that is softer
and that we call soft matter.
So my name is Cecile i'm a chemical
engineer although i'd probably describe
myself these days as a physical chemist
and i'm a soft matter scientist
so what i'm really interested in doing
in my research
is looking at the very very very small
sort of nanometer length scale, that's a
million times
smaller than a millimeter and
trying to understand how the structure
at this very very very small scale
affects the behavior of material so
basically how materials deform or flow
when we squeeze them or
spread them or pour them.
So to start with what is soft matter? So
soft matter is really
just materials that are made of
molecules but these molecules are
interacting through
quite weak interactions that we call
physical interaction so you've probably
heard about chemical
interactions or chemical bonds, they're
the really strong ones
that connect the atoms together in the
molecule.
In soft matter it's really the way
these molecules are then assembled into
other structures through these weak
physical interactions
so that makes stuff matter. But soft
matter
also is the stuff that you spread on
your face,
on your hair, on your body, that you brush
your teeth with
and the stuff that you put through your
mouth. Food basically,
or lots of foods at least
so here is something you can do at home:
look for the soft matter stuff that's
around you
and think about how they behave when you
squeeze them or scoop them or spread
them. It's all down to how the molecules
are organized at the very small scale.
So now you know that you've always known
about soft matter
without knowing that you knew about it.
Still, what is it made of? How are the molecules organized
and what molecules are they and
basically in other words
what is the common thing between the
cream you spread on your body
your shower gel, margarine or jelly
dessert?
so i'm going to tell you about two very
very important components
of soft matter
so the first really important character
in this play of soft matter
are surfactants and you may know them
under the name of
detergents although that's not
completely exactly the same thing but
it's
yeah so that's what you have in your
laundry liquid, in your
washing liquid, in your shower gels, all
sorts of things.
So what's really peculiar about
surfactants is they have
a dual personality so they have
a hydrophilic head group a water loving
head group
and a hydrophobic tail and these two
are connected by chemical bonds so they
cannot separate
so because of this very unusual
structure
surfactants like to absorb at interfaces so
basically they're very good at
stabilizing oil water interfaces because
one part that loves oil and hates water
will be in the oil and the other part
will be in the water
and this is how you clean dirt i mean
your clothes,
the fat on dishes,
or your body, or you know, your hair.
So that's quite convenient.
how do you think these molecules behave
when we throw them in water? i mean how
do they resolve that conflict
in their complex personality?
well basically when we throw them in
water the part that
hates water and wants to avoid water
just goes inside
and on the outside stay the part that
loves water and we end up with a
structure that looks a little bit like a
pom-pom
so with the hydrophobic bits in the
middle and the hydrophilic
head group on the outside. Of course
downsize
about 10 million times okay we're
talking really really small things
and so this structure is very useful as
we said just to clean
all the dirty stuff but you can also use
it to encapsulate
perfumes,
fragrant oils, flavors
you can also use it to encapsulate drugs
and in fact that's used in a lot of
your medicine formulations
so if you check some of the labels
you'll find lots of surfactants.
What other cool stuff about
surfactants i can tell you?
so we also have lots and lots of
surfactants in our body so we have
surfactants in our lungs they help us
breathe
and we have surfactants called bile
salts
in our digestive system that helps us
digest fat so in my research
i spend a lot of time looking at bile
salts and so
bile salts form my cells that
you know vaguely look like this, where
they encapsulate the the broken down
dietary lipids, so the fat that we eat,
and help
transport it to the gut mucosa where it
will be absorbed
by the body so surfactants are really
everywhere
here is something you can do at home. i'm
trying to mix oil in water which of
course is not possible unless you add
surfactants
so if you're making a mayonnaise the
surfactants would come from the egg
here i'm just adding some washing liquid.
It's not quite enough because i would
need to mix
very very vigorously for the oil
droplets to
stay stable but look how the samples look
different
so the second really important
component of soft stuff around you
are polymers and probably when you hear
the word polymer you think about
plastics you might think about teflon
that line your your pants or
polyesters in clothes or
other things like this but there are
actually polymers everywhere so
there are lots of natural polymers so
polysaccharides in particular, they are chains of sugars and they make up
most of our diet
so starch is a polymer, cellulose is a
polymer, that's the main
component in in plants and
it's everywhere in our body so
collagen, that makes up
our flesh or what we call the extra
cellular matrix, that's all the stuff
that is around cells and again
basically that make up our flesh
is a protein and therefore polymer,
and DNA
also is a polymer. So a polymer is a
very long molecule so again downsize
many many times
and when it's in water it tends to form
some sort of coil like this
and it's made of repeating
units so if you have a protein for
instance the repeating units are going
to be
amino acids but depending on the
chemical structure then the polymer will
have a very different
property and if you think about taking
another
polymer and making a chemical bond so
the very strong bonds that connect
um molecules together but you know if
you're connecting
polymer chains instead of small
molecules
you may end up with a structure
that looks like this,
you know with polymer chains connected
together in water
and that is the structure of a gel so
this is a model
for you know for your jelly dessert
for your hair gel
or you know other types of gels that you
may encounter
and so these these molecules are are
very helpful
for a lot source of applications you
find them
in nappies for instance you know why
nappies can
contain so much liquid is because you
have some sort of gel that swells
when it's in contact with the urine
but there are also all sorts of much
fancier applications  in biomedicine
for instance so
we use polymer gels for what we call
tissue engineering
so that's about repairing the body
repairing tissues and
why we can use gels for that is because
gels have a structure
very similar in terms of
the environment in terms of the chains
that are connected together
in terms of the mechanical properties so
how they deform
very similar to you know to our
flesh
and and you can design gels that are
gonna
mimic or resemble different parts
of our body so whether it's uh you know
a soft
tissue or harder tissue you can
change the the properties of the gels
to mimic that and this is why we need to
understand
the structure of these materials but
then also how are they going to deform
how they're going to flow so this is you
know part of what i do
as a researcher.
here i'm testing a nappy
as you can see the nappy absorbs all the
water
let's have a look at what's inside so
it's little
bits of gel which come from the polymer
that was inside the nappy
so i hope that by now you know just a
little bit more about
the the stuff that make up the soft
stuff that you um you know put on your
body or
eat or wash your clothes with
and i hope you're a little bit curious
to hear more about these
molecules and and how they're organized
at the very very
small scale and you might have ended up
thinking that i spent my days making
toothpaste
or gummy bears or yeah
but that's not the case so if you want
to hear
more about the the techniques that i use
in in my lab
to look uh you know at things at the
very very small scale
or to understand how things uh flow and
deform
please join the conversation next next
week with a soapbox science
and um please also post um questions
on my padlet so it's just like a posting
uh
posted uh notes so just ask anything you
know
uh how can you use gels to repair the
body
you know how how do you look at
molecules at this length scale or
you know how do we digest fat with bile
salts or you know whatever
you can also do that on twitter with the
hashtag
um everyday soft stuff
thank you for watching
hi everybody thank you for joining me
for soapbox science
i'm Monni Bohm, i'm a research fellow at
the Zoological Society of London's
institute of zoology
and today i thought i'd record this
video from my local park
because a why not and b well everything
in 2020 has just been
this tiny little bit different hasn't it?
so now when i don't video talks in my
local park
which is quite often i am researching
how nature is doing worldwide
or to use a bit more science speak
our research group at ZSL is monitoring
global biodiversity- how are the world's
living things
animals, plants, fungi, that's what we refer
to as biodiversity
how are they doing? Are they doing okay?
and if not
why are they not doing okay what are the
threats to them and what do we need to
do about
fixing these threats so that
biodiversity or species can thrive in
our world
now first of all the big question how is
biodiversity doing worldwide? How are
species doing?
You're probably you've probably heard
about threatened species or
declines in wildlife populations in the
in the news
um so it might not come to you as a big
shock when i tell you that wildlife
overall isn't doing
great. But how do we know that wildlife
isn't doing great and how do we put this
into numbers because
that's what scientists do right we like
to take some data some observations and
put this into numbers and make sense of
them.
Now quite often scientists have a very
specific study species that they're
focusing their work on
i used to study badges for example.
Other scientists may go to the same
patch of wood or to the same park
much like this one here
to regularly count the number of certain
species
birds for example, like that slightly
judgmental magpie over there that keeps
staring at me.
Or the number of butterflies they come
across type of species they come across
or they may use camera traps for more
elusive species to monitor those
or for marine biologists they might take
a boat out onto the sea
and count whale sightings for example
now what i research is the global
picture of how nature is doing worldwide
so i don't
look specifically at specific species in
the field
what we do is we collate information
that was gathered by other species
experts by ecologists
other scientists to mash all of this
information
together into essentially one measure
that tells us something about the health
of nature or the status and trends of
nature
over time and that's and that's a big
word alert is what we call
a biodiversity indicator
now my work particularly focuses on one
specific
biodiversity indicator which looks at
the extinction risk of species
now how do we know if a species is at a
higher extinction risk than another
species for example we've all heard
about
species being close to extinction in the
news but how do scientists know that
now we know for example that some
species and i am just being
stared at by a fox that some species
have large
large population numbers there's many
individuals in that species
and so these have a lower extinction
risk than species with a small number of
individuals think of it as the pins in a
bowling
game if you've only got few pins and
they're ideally close together so they
probably also have a restricted range
over which they occur
and a single thread process can easily
bowl over
all the leftover pins or the leftover
individuals in your species
so a small population size and a
restricted range
lead to a higher extinction risk in
species now species with population that
are declining really really rapidly for
example are at a higher risk of
extinction because these species are
hurtling towards smaller and smaller
population sizes and hence higher and
higher extinction risk
compared to say species that have slowly
declining populations or stable
populations
now scientists have been assessing the
extinction risk of a large number of
species for a very very long time using
a scheme that was devised by the
international union for conservation of
nature
or short IUCN called the IUCN red list
of threatened species
now the IUCN red list essentially
collates information on these different
factors that i was just talking about
to categorize the extinction risk of
species
now here you can see the extinction risk
scale that the IUCN uses
from the lower risk categories
LC here for least concern the species
that have wide ranges
all the way to near threatened so it's
starting to get a little bit
more problematic in terms of threats
impacting the species
to the threatened categories of
vulnerable endangered critically
endangered and ultimately to the extinct
categories
extinct in the wild and extinct
now i quite often look at the IUCN red
list process a little bit
as if it's a game of playing top trumps
you know the card game where you have
cards i always used to have cards of
cars or ships or planes when i was a kid
where each card has a particular type of
of car or ship or plane on it and
summarizes some statistics about it and
then the aim of the game is that
your card trumps the opponent's card in
a particular statistic
aim is of course to win all of the cards
now you're probably wondering what i'm
going on about, top trumps what?
now here's an example i made up earlier
and it's actually also an example that
illustrates some of the species that
i've been
working on over the past few years no
nothing
nothing quite cute and fluffy more
things like
these guys yeah that works better
the fatmucket and the pink mucket now
they are both freshwater mussels
so they are invertebrates that live in
river systems
in north america now they look very
similar they're very closely related so
you might think they also have a similar
extinction risk
however let's play top trumps
so let's play red list top trumps
the fatmucket has a stable population
trend
whereas the pink mucket is decreasing by
more than 30 percent
that means the fatmucket is doing better
or has a lower extinction risk than the
pink mucket
similarly the fatmucket
has a distribution of more than 5
million kilometers squared
the pink mucket only 230 000 odd
square kilometers fatmucket
least concern pink mucket vulnerable on
the IUCN red list of threatened species
so why do we need to assess the
extinction risk of say
mussels or dung beetles
because it is these tiny species that a
have been vastly understudied
in the past specifically for
conservation conservation is
traditionally often focused
on mammals or birds for example
and also extinction risk assessments
have been carried out for mammals and
birds but
much less so for other species and it is
also often these tiny species like the
mussels
or the dung beetles that provide really
essential services to our ecosystems and
habitats and keep them healthy
mussels for example are really important
in filtering a lot of water in
freshwater systems for example and
keeping fresh waters nice and clean
and also by assessing the extinction
status of these tiny little
often overlooked species and i say tiny
little i'm actually going to show quite
a big example here
we're missing out on some really
charismatic species that we probably
hadn't thought about yet this guy for
example the queen alexandra's bird wing
now that is the largest butterfly in the
world think of a flying
dinner plate it's kind of that size 25
centimeter wingspan
now this is a species that occurs in
papua new guinea and has just recently
been assessed by us for the iucn red
list
assessed as endangered so the second
highest threat category now the reason
why i am so interested for my research
in assessing these lesser-known species
for the iucn red list is the iucn red
list index now the iucn red list index
is essentially what you can see on the
screen now it's you know you can see i
don't know
one two three four five six different
lines
and they are lines that show us the
trend in extinction risk for
a number of species groups so for
example you can see the birds there's a
bird perched on that line
it's this one up here that's the group
that's currently doing
the best out of the ones that have been
assessed now the point of my research
and the research of lots of other people
that i collaborate with
is to put more points onto this red list
graph
now this is an example that's taken from
a recently published paper by
by some of our collaborators at the
natural history museum which already
adds a number of groups to
to this graph that we've just seen we've
got the dragonflies and damselflies
reptiles plants
and you can see that freshwater crabs
and crayfish for example they're kind of
quite low down in terms of their status
they're doing worse than some of the
other groups that have already been
assessed
and so in a tiny to medium-sized
nutshell this is what my research is
trying to do
we're trying to fill the gap in our
knowledge for some of these understudied
species groups that haven't yet made it
into these big biodiversity indicators
and that are not
really taken too much into account when
we think about
big global conservation policy and how
we can stop biodiversity declines
and yes so sometimes my research feels a
little bit like playing a game of top
trumps
sometimes my research takes a long time
talking to a lot of different species
experts about their species and how
they're doing to compile
information across entire species groups
for example
and most of the time it's just great fun
i think the fox has wandered off now
foxes the european fox that we
we see in london for example least
concern on the iucn red list of
threatened species
hi i'm Choong Ling Liew-Cain i'm a phd
student in University College London
space and climate physics department i
study galaxies and specifically how
nearby galaxies grow
today i'll be talking to you about
galaxy's journeys through time
from their formation to the present day
a galaxy is a collection of stars and
dark matter
these stars form out of gas and all
orbit around a supermassive black hole
in the center of the galaxy
in an average galaxy like our own there
are 100 billion stars
or roughly one star for every 10 grains
of sand like these
on the surface of the earth so what
we've got here is the universe
about 400 million years after the big
bang
so it's a bit of squidgy foam for this
and
this point in the universe there weren't
any stars or galaxies
there was just some gas which we're
going to represent here with some black
sand which i'm sprinkling over the
universe now
a little bit more and the gas in the
universe at this time
wasn't distributed evenly over it there
were some bits like over here
that were a bit clumpy and these clumps
had stronger gravity
than the area around them so what
happened was the gravity pulled down
like this and made the clamp a little
bit bigger
and we'll do a similar one like over
here
and then over here as well
and then these clumps now you can see
are a bit bigger and more defined so
that means that their gravity is even
stronger
so what happens then is the gravity
again pulls down a lot stronger this
time
and so the clumps get even bigger again
and again and again
like this so what you end up with is a
universe that's
full of uh voids like over here and here
where there aren't actually that much
gas
and then nodes over here where all our
clumps work to begin with
where there is a lot of gas and some
galaxies form and then also filaments
which is just
shorter bits of gas normally quite long
between the nodes
where you also get a few galaxies as
well
there are two main types of galaxies the
first is an elliptical galaxy which are
generally red in color and have a shape
somewhere between a ball and a sausage
now these galaxies are almost entirely
made up by stars
there isn't any dust or gas left in them
they're also usually very old
the other type of galaxy is a spiral or
a disc galaxy
which are usually blue and yellow and
quite a bit younger
our galaxy the milky way is a spiral
galaxy
it's called a spiral galaxy because it
looks like it has arms that spiral
around each other where the bright arms
are where there's lots of stars
and the darker areas are where there's a
lot of dust which block out the light
from the stars
the milky way is 100 000 light years
thick
or 60 to 95 billion miles in diameter
and about 2 000 light years or 11
trillion miles thick
this is the same width to thickness
ratio as two cds
stacked on top of each other like this
and one of the reasons why they're
called disc galaxy is that it's shaped
like a cd as well
so disc galaxies can look rather
different depending on the angle you
look at them
either face on we can clearly see any
spiral patterns that might be present
as they wrap around like this or if you
look at them edge on
where you can only see a little bit of
the disc here and then maybe a bulge in
the middle like where my thumb is
and you could also see them perhaps
somewhere in between like this
so the main way that galaxies grow is by
merging together to create one galaxy
that's the size of the two galaxies that
merge together
combined so there are kind of two main
situations for these
the first one is where you've got a big
galaxy so this could be the size of the
milky way
or about 100 billion times
the mass of the sun and that can merge
with a smaller galaxy as you can see
here in red which would maybe be
100 000 times the mass of the sun
so what happens in a situation like this
is the smaller dwarf galaxy in red
will come in on a trajectory like this
and then we'll start orbiting around
the larger galaxy like this and it will
leave a small trail
of stars behind it to make a nice stream
that you can see
and then this galaxy will move in closer
and closer until it all until it reaches
and falls into the main galaxy
that it was following and then the
stream
of stars keeps moving around following a
similar trajectory
coming in closer again wrapping around
and creating a blob like this
and the main galaxy in this case is
mostly untouched and you can see that
here
because there's still quite a lot of
blue sand that shows through the red
sand
so the other type of merger can happen
when both of the galaxies are around the
same size
so for example this is going to happen
to the milky way
in about four to five billion years it's
going to merge with andromeda which is
the closest galaxy
to us now so what happens in this case
is the galaxies come in like this and
then at the same time
they move around each other
like this creating nice tails
going around they can also move through
each other a bit so you get something
like that coming where it picks up a lot
of stars from the other galaxy
they keep moving around and around
spiraling in
and then after several billions of years
you get a nice stable galaxy that could
look a bit like an elliptical or a
spiral galaxy as we talked about before
and that it would look something a bit
like this and you can
and there's a lot more disruption to
both of the galaxies this time
which you can tell compared to the other
merger because you can see that this one
in color looks a lot more mixed than
this one
