6,593 research outputs found
Lithographically and electrically controlled strain effects on anisotropic magnetoresistance in (Ga,Mn)As
It has been demonstrated that magnetocrystalline anisotropies in (Ga,Mn)As
are sensitive to lattice strains as small as 10^-4 and that strain can be
controlled by lattice parameter engineering during growth, through post growth
lithography, and electrically by bonding the (Ga,Mn)As sample to a
piezoelectric transducer. In this work we show that analogous effects are
observed in crystalline components of the anisotropic magnetoresistance (AMR).
Lithographically or electrically induced strain variations can produce
crystalline AMR components which are larger than the crystalline AMR and a
significant fraction of the total AMR of the unprocessed (Ga,Mn)As material. In
these experiments we also observe new higher order terms in the
phenomenological AMR expressions and find that strain variation effects can
play important role in the micromagnetic and magnetotransport characteristics
of (Ga,Mn)As lateral nanoconstrictions.Comment: 11 pages, 4 figures, references fixe
Platelet lysate maintains chondrogenic potential and promotes cartilage regeneration
cartilage.
We
report
the
biological
effect
of
the
platelet
lysate
(PL),
a
PRP
derivative,
on
primary
human
articular
chondrocytes
(HAC)
cultured
under
both
physiological
and
inflammatory
condition.
Added
to
the
culture
medium,
PL
induced
a
strong
mitogenic
response
in
the
chondrocytes.
The
in
vitro
expanded
cell
population
maintained
a
chondrogenic
re-Ââdifferentiation
potential
as
revealed
by
micromass
culture
in
vitro
as
well
as
in
vivo
as
demonstrated
by
ectopic
cartilage
formation
in
nude
mice.
Furthermore,
in
chondrocytes
cultured
in
the
presence
of
the
pro-Ââinflammatory
cytokine
IL-Ââ1α,
the
PL
induced
a
drastic
enhancement
of
the
synthesis
of
the
cytokines
IL-Ââ6
and
IL-Ââ8
and
of
NGAL,
a
lipocalin
expressed
in
cells
of
the
chondrogenic
lineage.
These
events
were
controlled
by
the
p38
MAP
kinase
and
NF-ÂâÎșÎ
pathways.
The
pro-Ââinflammatory
effect
of
the
PL
was
a
transient
phenomenon.
In
fact,
after
an
initial
up
regulation,
we
observed
a
significant
reduction
of
the
NF-ÂâÎșÎ
activity
together
with
the
repression
of
the
inflammatory
enzyme
ciclooxygenase-Ââ2
(COX-Ââ2).
Moreover,
the
medium
of
chondrocytes
cultured
in
the
contemporary
presence
of
PL
and
IL-Ââ1α,
showed
a
significant
enhancement
of
the
chemoattractant
activity
versus
untreated
chondrocytes.
On
the
whole,
our
findings
support
the
concept
that
the
platelet
products
have
a
direct
beneficial
effect
on
articular
chondrocytes
and
at
the
same
time
could
drive
in
sequence
a
trans
The aberrant expression in epithelial cells of the mesenchymal isoform of FGFR2 controls the negative crosstalk between EMT and autophagy
Signalling of the epithelial splicing variant of fibroblast growth factor receptor 2 (FGFR2b) triggers both differentiation and autophagy, while the aberrant expression of the mesenchymal FGFR2c isoform in epithelial cells induces impaired differentiation, inhibition of autophagy as well as the induction of the epithelial-mesenchymal transition (EMT). In light of the widely proposed negative loop linking autophagy and EMT in the early steps of carcinogenesis, here we investigated the possible involvement of FGFR2c aberrant expression and signalling in orchestrating this crosstalk in human keratinocytes. Biochemical, molecular, quantitative immunofluorescence analysis and in vitro invasion assays, coupled to the use of specific substrate inhibitors and transient or stable silencing approaches, showed that AKT/MTOR and PKCΔ are the two hub signalling pathways, downstream FGFR2c, intersecting with each other in the control of both the inhibition of autophagy and the induction of EMT and invasive behaviour. These results indicate that the expression of FGFR2c, possibly resulting from FGFR2 isoform switch, could represent a key upstream event responsible for the establishment of a negative interplay between autophagy and EMT, which contributes to the assessment of a pathological oncogenic profile in epithelial cells
Encapsulation of human articular chondrocytes into 3D hydrogel : phenotype and genotype characterization
This chapter is intended to provide a summary of the current materials used in cell encapsulation technology
as well as methods for evaluating the performance of cells encapsulated in a polymeric matrix. In
particular, it describes the experimental procedure to prepare a hydrogel matrix based on natural polymers
for encapsulating and culturing human articular chondrocytes with the interest in cartilage regeneration.
Protocols to evaluate the viability, proliferation, differentiation, and matrix production of
embedded cells are also described and include standard protocols such as the MTT and [3H] Thymidine
assays, reverse transcription polymerase chain reaction (RT-PCR) technique, histology, and immunohistochemistry
analysis. The assessment of cell distribution within the 3D hydrogel construct is also described
using APoTome analysis.(undefined
Voltage control of magnetocrystalline anisotropy in ferromagnetic - semiconductor/piezoelectric hybrid structures
We demonstrate dynamic voltage control of the magnetic anisotropy of a
(Ga,Mn)As device bonded to a piezoelectric transducer. The application of a
uniaxial strain leads to a large reorientation of the magnetic easy axis which
is detected by measuring longitudinal and transverse anisotropic
magnetoresistance coefficients. Calculations based on the mean-field
kinetic-exchange model of (Ga,Mn)As provide microscopic understanding of the
measured effect. Electrically induced magnetization switching and detection of
unconventional crystalline components of the anisotropic magnetoresistance are
presented, illustrating the generic utility of the piezo voltage control to
provide new device functionalities and in the research of micromagnetic and
magnetotransport phenomena in diluted magnetic semiconductors.Comment: Submitted to Physical Review Letters. Updates version 1 to include a
more detailed discussion of the effect of strain on the anisotropic
magnetoresistanc
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