Diffusion power spectra as a window into dynamic materials architecture
Science Advances,
Год журнала:
2025,
Номер
11(15)
Опубликована: Апрель 11, 2025
Chemical
recycling
of
commodity
and
specialty
polymers
presents
a
multifaceted
challenge
for
industrial
societies.
On
one
hand,
macromolecular
architectures
must
be
engineered
to
yield
durable
products
that,
on
the
other
rapidly
deconstruct
recyclable
monomers
under
pre-determined
conditions.
Polymer
deconstruction
is
chemical
process
that
requires
deep
understanding
molecular
reactivity
in
heterogeneous
media,
where
porous
material
evolve
both
space
time.
To
build
this
understanding,
we
develop
herein
experimental
analytical
methods
describing
sets
diffusive
eigenmodes
exist
within
time-varying,
non-Euclidean
boundary
conditions,
situation
commonly
encountered
reactive
chain
fragments
splay,
alter
their
local
dynamics,
confinement
reacting
media.
Diffusion
power
spectra,
discerned
experimentally
by
NMR,
polymer
solvent
frequency-domain
velocity
autocorrelation
functions
are
analyzed
context
physical
models
reactions
parameterized
with
fractal
mathematics.
The
results
connect
motion
during
acidolysis
circular
elastomers.
Язык: Английский
Revisiting classical diffusion magnetic resonance methods as a means to measure time-dependent diffusion
Magnetic Resonance Letters,
Год журнала:
2025,
Номер
unknown, С. 200197 - 200197
Опубликована: Апрель 1, 2025
Язык: Английский
Measuring the velocity autocorrelation function using diffusion NMR
The Journal of Chemical Physics,
Год журнала:
2025,
Номер
162(17)
Опубликована: Май 2, 2025
Molecular
self-diffusion
in
the
presence
of
barriers
results
time-dependent
displacements
that
are
controlled
by
barrier
characteristics,
such
as
thickness,
arrangement,
and
permeability,
which
manifests
itself
form
ensemble-average
velocity
autocorrelation
function
(VAF).
We
describe
a
direct
method
to
measure
VAF
based
on
combination
diffusion-weighted
nuclear
magnetic
resonance
(NMR)
measurements
two
time-shifted
diffusion
encodings
separated
longitudinal
storage
period.
The
estimated
from
simulated
data
is
shown
agree
with
known
expression
for
impermeable
parallel
planes.
Simulations
periodically
spaced,
permeable
planes
connected,
box-shaped
pores
also
presented.
find
scaling
faster
than
t−1/2
indicative
permeation
or
exchange
between
domains
this
can
be
captured
proposed
method.
As
an
experimental
proof-of-concept,
we
present
ex
vivo
neonatal
mouse
spinal
cord
studied
using
permanent
magnet
NMR
MOUSE
system.
report
transition
t−3/2
at
t
≈
10
ms,
consistent
perhaps
transmembrane
water
exchange.
Compared
other
NMR-based
approaches,
potentially
access
several
orders
magnitude
time
(ms
–
s),
revealing
wealth
behaviors
one
paradigm.
Язык: Английский
Hydrophysiology NMR reveals mechanisms of steady-state water exchange in neural tissue
bioRxiv (Cold Spring Harbor Laboratory),
Год журнала:
2024,
Номер
unknown
Опубликована: Дек. 13, 2024
SUMMARY
Water
molecules
exchange
incessantly
across
cell
membranes
and
among
different
environments
within
the
cell,
but
it
is
not
known
what
dominant
transport
pathways
are
whether
they
active
or
passive.
We
have
developed
realtime
NMR
hydrophysiology
methods
to
study
steady-state
water
diffusion
in
viable
ex
vivo
neonatal
mouse
spinal
cord
samples.
find
that
linked
tonicity
maintained
by
transport.
Exchange
slows
following
sodium–potassium
pump
inhibition
recovers
a
normal
rate
after
adding
extracellular
osmolytes.
Additional
information
from
apparent
coefficients
(ADC)
differentiates
inactive
samples
regardless
of
tonicity.
Data
modeling
suggest
multisite
mechanism
which
modulates
pathway
between
fast
transmembrane
slow
intracellular
exchange.
The
has
high
activation
energy
does
require
ions,
suggesting
this
likely
occurs
through
lipid
bilayer
rather
than
channels
cotransporters.
These
may
one
day
be
translated
clinical
MRI
scanners
determine
features
cellular
state
.
steady
exchange,
homeostasis,
spectroscopy,
DEXSY,
tissue
microstructure,
porous
media,
membrane
permeability,
low-field
single-sided
NMR,
coefficient,
ADC,
gray
matter
Язык: Английский