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Previous research showed that automatic emotion regulation is associated with activation of subcortical areas and subsequent feedforward processes to cortical areas. In contrast, cognitive awareness of emotions is mediated by negative feedback from cortical to subcortical areas. Pregenual anterior cingulate cortex (pgACC) is essential in the modulation of both affect and alexithymia. We considered the interplay between these two mechanisms in the pgACC and their relationship with alexithymia.
In 68 healthy participants (30 women, age = 26.15 ± 4.22) we tested associations of emotion processing and alexithymia with excitation/inhibition (E/I) balance represented as glutamate (Glu)/GABA in the pgACC measured via magnetic resonance spectroscopy in 7 T.
Alexithymia was positively correlated with the Glu/GABA ratio (N = 41, p = 0.0393). Further, cognitive self-awareness showed an association with Glu/GABA (N = 52, p = 0.003), which was driven by a correlation with GABA. In contrast, emotion regulation was only correlated with glutamate levels in the pgACC (N = 49, p = 0.008).
Our results corroborate the importance of the pgACC as a mediating region of alexithymia, reflected in an altered E/I balance. Furthermore, we could specify that this altered balance is linked to a GABA-related modulation of cognitive self-awareness of emotions.
With modern techniques, neutron-capture cross sections can be determined with uncertainties of a few percent. However, Maxwellian averaged cross sections calculated from such data require a correction (because low-lying excited states are thermally populated in the hot stellar photon bath) which has to be determined by theoretical calculations. These calculations can be improved with information from indirect measurements, in particular by the inelastic scattering cross section. For low-lying levels, the inelastically scattered neutrons are difficult to separate from the dominant elastic channel. This problem is best solved by means of pulsed, monoenergetic neutron beams. For this reason, a pulsed beam of 30 keV neutrons with an energy spread of 7 to 9 keV FWHM and a width from 10 to 15 ns has been produced at Forschungszentrum Karlsruhe using the 7Li(p, n)7Be reaction directly at the reaction threshold. With this neutron beam the inelastic scattering cross section of the first excited level at 9.75 keV in 187Os was determined with a relative uncertainty of 6%. The use of monoenergetic neutron beams has been further pursued at the Physikalisch-Technische Bundesanstalt in Braunschweig, including the 3H(p, n)3He reaction for producing neutrons with an energy of 64 keV.
Biomolecules rich in aspartic acid (Asp) are known to play a role in
biomineral morphology and polymorph selection, and have been shown to
greatly enhance the growth kinetics of calcite. The mechanism by which these
compounds favor calcification may be related to their effects upon cation
solvation. Using molecular dynamics, we investigated the influence of small
carboxylated molecules on the hydration states and water exchange rates of
divalent cations. We show that the carboxylate moieties of Asp promote
dehydration of Ca2+ and Sr2+ and that contact ion pair
(CIP) formation is not required to disrupt the hydration of these cations.
Ca2+- Asp and Sr2+ - Asp CIP formation decreases
the total inner sphere coordination from an average of 8.0 and 8.4 in bulk
water to 7.5 and 8.0, respectively. Water residence times estimated for
Mg2+, Ca2+and Sr2+ follow the expected
trend of decreasing residence time with increasing ionic radius. In the
presence of Asp, both solvent-separated ion pair (SSIP) and CIP formation
decrease the residence times of Ca2+and Sr2+ inner
sphere water molecules. Comparable impacts on Mg2+ hydration are
not observed. Mg2+ - Asp CIP formation is energetically
unfavorable and Asp does not affect Mg2+ inner sphere water
A recent approach in disease diagnosis and viral epidemics is aimed at
point-of-care tests that could be administered near the patient rather than
time-consuming processes involving centralized laboratories. Point-of-care
devices provide rapid results in simple and low-cost manner requiring only
small sample volumes. These devices will strongly benefit from advanced
materials and fabrication methods to improve their efficiency and
sensitivity. We report a functionalized carbon nanotube label for an
immunosensor application. Carbon nanotube label was prepared by modifying
the carbon nanotube surface to anchor biomolecules. First, the carboxylic
acid treated multi-walled carbon nanotubes (MWCNTs) were uniformly dispersed
with polyvinylpyrrolidone (PVP) by sonication in aqueous solution. PVP
partially wraps around the carbon nanotubes and exposes the surface of the
nanotubes for further functionalization. The MWCNTs were then conjugated
with human immunoglobulin G (IgG) using EDC/Sulfo-NHS coupling chemistry,
where the antibodies occupied sites not covered by PVP. The dispersion,
surfactant modification, and antibody conjugation of the MWCNTs were also
confirmed using SEM and TEM images. The successful functionalization of the
MWCNTs and reactivity of the covalent attached antibodies were demonstrated
for specific antigen binding on the microelectrode device. The carbon
nanotube-based detection mechanism could be tailored for screening various
analyte specific molecules. Furthermore, the reported technique could easily
be integrated in various microfluidic and lab-on-a-chip devices for the
development of functional electronic sensors providing quantitative,
sensitive, and low-cost detection in pointof- care setup.
Porous scaffolds of alkaline-soluble collagen including nanocomposite
particles of chondroitin sulfate and low crystalline hydroxyapatite for
cartilage regeneration were fabricated by freeze-drying and thermal
dehydration treatments; porous collagen scaffolds were also synthesized as a
reference. The scaffolds were cross-linked using glutaraldehyde (GA) vapor
treatment in order to enhance biodegradable resistance. Microstructural
observation with scanning electron microscope indicated that the scaffolds
with and without GA cross-linkage had open pores between 130 to 200 μm in
diameter and well-interconnected pores of 10 to 30 μm even after
cross-linkage. In vitro biodegradable resistance to
collagenase was significantly enhanced by GA cross-linking of the scaffolds.
All these results suggest that the GA cross-linked scaffolds consisting of
collagen, chondroitin sulfate, and low crystalline hydroxyapatite have
suitable microporous structures and long-term biochemical stability for
cartilage tissue engineering.
This article presents the first man-made material based on the structure of
nacre that successfully duplicates the mechanism of tablet sliding. This
material was made of millimeter size PMMA tablets arranged in columns and
held by fasteners. Strain hardening was provided by tablet waviness,
delaying localization and leading to strains at failure 3-5 times greater
than bulk PMMA. Analytical and finite element models successfully captured
the locking mechanisms, enabling a rigorous design and optimization of
similar composites based on different materials or at different length
scales. This work demonstrates how key features and mechanisms in natural
nacre can be successfully harnessed in engineering materials. Interestingly,
the development of this model material and of its associated models also
unveiled two new mechanisms, the effect of free surfaces and “unzipping”.
Both mechanisms may be relevant to natural materials such as nacre or
In this study, the morphological changes of chemically treated (or
preserved) with aqueous solutions of 1) a sodium chloride (NaCl) and 2) a
compound containing sodium silicate, so called “wasserglass”, and untreated
I-type collagen fibers of Mongolian goatskin are investigated by atomic
force microscopy in ambient condition and at room temperature. The
experimental results show that the difference between D period for both
chemically treated and untreated collagen fibers are a relatively stable for
morphological behavior. However, we find that the width of collagen fibers
treated with the NaCl solution is more increasing with approximately 112 nm
than those of samples (untreated and treated with wasserglass solution) for
the range 93.4-94.8 nm. We also observe that a typically structure of the
collagen fibers generally, a dense packing of the untreated and treated by
wasserglass collagen fibers in bundles in a nearly parallel arrangement,
with little changes in orientation can be seen. The collagen fibers treated
by NaCl are a more destructive than untreated and treated by wasserglass for
We describe two techniques to create sharp tips. The first involves the
buckling of thin metal films deposited on soft, stretchable substrates. The
second involves the formation of narrow necked capillary bridges.
Electroless synthesis and hierarchical organization of 1.4 nm Pd and Pt
nanoparticles (NPs) on self-assembled Rosette Nanotubes (RNTs) is described.
The nucleated NPs are nearly monodisperse and reveal supramolecular
organizations guided by RNT templates. Interestingly, the narrow size
distribution is attributable to unique templating behavior of RNTs. The
resulting metal NP-RNT composites were characterized by Atomic Force
Microscopy (AFM), Scanning Electron Microscopy (SEM) and Transmission
Electron Microscopy (TEM). X-ray Photoelectron Spectroscopy (XPS) was also
performed to confirm the nature and composition of RNT-templated NPs.
Chemotaxis is one of the essential mechanisms responsible for various
complex biological processes. For a crawling cell, the interface between the
cell and the substrate plays an important role in the chemotactic migration.
This paper presents a three-dimensional dynamic model to investigate the
effect of the interface between a crawling cell and a substrate on its
chemotaxis. The coupled mechanisms of chemotaxis, the surface energy of the
cell, and the interface between the cell and the substrate are incorporated
into a diffuse interface model. Simulations reveal rich dynamics of a
crawling cell associated with the interfacial condition, and confirm the
high possibility of adequate predictions.
Mineralized biological materials such as nacre and bone achieve remarkable
combinations of stiffness and toughness through staggered arrangements of
stiff components bonded by softer materials. These natural composites are
therefore substantial source of inspiration for emerging synthetic
materials. In order to gain new insights into structureperformance
relationships of these staggered structures, nacres from four species were
compared in terms of fracture toughness and damage propagation pattern.
Fracture tests revealed that all nacres display rising crack resistance
curves, but to different extents. Using in-situ optical and atomic force
microscopy, two distinct patterns of damage propagation were identified in
columnar and sheet nacre respectively. These two different patterns were
further confirmed by means of large scale numerical models of staggered
structures. Similar mechanisms possibly operate at the smallest scales of
the microstructure of bone.
The atypical mechanical behavior of white matter and its influence on the
mechanical properties of brain tissue necessitate adoption of a mutli-scale
model of white matter for accurate computational analysis. Herein, we
present a micromechanical analysis coupled with finite elements into a
biomechanical interacting model of white matter. A representation of the
white matter of central nervous system is identified and its microstructure
is generated. The geometric descriptions of the axon and the surrounding
matrix are obtained from neurofilament immunohistochemistry images.
Consecutively, linear elastic material constitutive models are applied to
describe the behavior of axons and their surrounding matrix subjected to
small deformations. This model facilitates determination of the tissue’s
stress and strain fields, and enables an understanding of the effects of
axon undulation on local fields. The fundamental nature of the model enables
future scale-up for structural tissue analysis and predictions of axon
damage at the microscale.
A key issue in using Polydimethylsiloxane (PDMS) based micropillars as
cellular force transducers is obtaining an accurate characterization of
mechanical properties. The Young’s modulus of PDMS has been extended from a
constant in the ideal elastic case to a time-dependent function in the
viscoelastic case. However, the frequency domain information is of more
practical interest in interpreting the complex cell contraction behavior. In
this paper, we reevaluated the Young’s relaxation modulus in the time domain
by using more robust fitting algorithms than previous reports, and
investigated the storage and loss moduli in the frequency domain using the
Fourier transform technique. With the use of the frequency domain modulus
and the deflection of micropillars in the Fourier series, the force
calculation can be much simplified by converting a convolution in the time
domain to a multiplication in the frequency domain.
We describe the biosynthesis and characterization of protein materials
comprised of two distinct self-assembling domains (SADs): elastin (E) found
in tissue for its elastic properties and cartilage oligomeric matrix protein
coiled-coil (COMPcc, C) predominantly locatedin joint and in bones. Based on
earlier studies on protein block polymers comprised these two SADs,
orientation and number of blocks play a crucial role in the overall
stimuli-responsive supramolecular assembly behavior. Here we fabricate a
range of EnC and CEn block polymers in which the E
domain is systematically truncated to explore the effects of the E domain on
the overall physicochemical behavior.
We report the heterogeneous integration of a multifunctional sensor based on
polymer porous photonic bandgap (P3BG) structure and xerogel
based luminescence sensor technology. The P3BG structure was
fabricated using holographic interferometry. Initially, holographic
interferometry of a photo-activated prepolymer syrup that included a
volatile solvent as well as monomer, photoinitiator, and co-initiator was
used to initiate photopolymerization. Subsequent UV curing resulted in well
defined lamellae of the polymer separated by porous polymer regions that
created a high quality photonic bandgap structure. The resulting
P3BG structure was then integrated with the xerogel based
luminescence element to produce a luminescence sensor with a selective
narrow band reflector. The prototype xerogel based luminescence sensor
element consisted of an O2 sensing material based on spin coated
tetraethylorthosilane (TEOS) composite xerogel films containing tris
(4,7-diphenyl-1,10-phenanthroline) ruthenium (II)
([Ru(dpp)3]2+) luminophore. We demonstrated
enhancement of the signal-to-noise ratio (SNR) of this integrated
multifunctional sensor while maintaining the same sensitivity to
O2 sensing of the xerogel based element. The resulting
advantages and enhanced SNR of this integrated sensor will provide a
template for other luminescence based assays to support highly sensitive and
cost-effective sensor systems for biomedical applications.
Photosynthetic membrane proteins convert solar light into chemical energy in
a significantly high efficiency. Up-to-date reports of the photosynthetic
bacterium suggest that such effective light conversion is due to the energy
transfer between two light-harvesting (LH) protein complexes that are
patterned in two dimensions. In this report, LH complex isolated from
Rb. sphaeroides was immobilized onto a patterned gold
surface with self-assembled monolayers (SAMs) and lipid bilayers at two main
objectives: (1) micron-scale patterning of LH complex, and (2) prevention of
quenching for pattern observation.
Molecular dynamics simulations were performed to estimate sequence dependent
force required to stretch single stranded DNA (ssDNA) homo oligonucleotides.
Simulations suggest that polyA and polyC oligonucleotides exhibit similar
force profiles and corresponding elongation. Among single stranded DNA
strands polyT is the most flexible and needs the most force to unwind from
an equilibrium folded structure. In contrast, polyG had a very small
recoverable deformation prior to a non-linear stretching. Our results
indicate that mechanical properties of ssDNA chains are directly related to
In recent years there has been a renewed interest in magnesium alloys for
applications as temporary biomedical implants because magnesium is both
biocompatible and biodegradable. However, the rapid corrosion rate of
magnesium in physiological environments has prevented its successful use for
temporary implants. Since alloying is one of the routes to slow down
corrosion, we report in this publication our investigation of Mg-Ti alloys
fabricated by high-energy ball milling as possible materials for
biocompatible and biodegradable implants. Titanium was chosen mainly because
of its proven biocompatibility and corrosion resistance. Corrosion tests
carried out by immersing the Mg-Ti alloys in Hank’s Solution at 37°C showed
significantly improved corrosion resistance of the alloy in comparison to
pure magnesium. Thus, Mg-Ti alloys are promising new biodegradable and
biocompatible materials for temporary implants.