645 research outputs found
BaFe2As2/Fe bilayers with [001]-tilt grain boundary on MgO and SrTiO3 bicrystal substrates
Co-doped BaFe2As2 (Ba-122) can be realized on both MgO and SrTiO3 bicrystal
substrates with [001]-tilt grain boundary by employing Fe buffer layers.
However, an additional spinel (i.e. MgAl2O4) buffer between Fe and SrTiO3 is
necessary since an epitaxial, smooth surface of Fe layer can not be grown on
bare SrTiO3. Both types of bicrystal films show good crystalline quality.Comment: Accepted for the ISS2012 Proceedins, a special issue of Physics
Procedi
Festkörper-NMR-Untersuchungen zur Strukturaufklärung mesostrukturierter Aluminiumphosphate
Mittels Festkörper-NMR-Experimenten wurde die Struktur unterschiedlicher mesostrukturierter Aluminiumphosphate im Detail untersucht. Hierzu wurden verschiedene ein- und zweidimensionale Festkörper-NMR-Experimente, wie beispielsweise das HETCOR-, Doppelquanten-, Triplequanten- und RFDR-Experiment an den Kernen 1H, 13C, 27Al und 31P eingesetzt. Zudem wurden Untersuchungen zur gezielten Synthese mesostrukturierter Aluminiumphosphate sowie deren Phasenumwandlungen durchgeführt
Cadomian and Variscan metamorphic events in the Léon Domain (Armorican Massif) resolved by trace element analysis in monazite and garnet
The question, whether crustal domains
are allochthonous terranes or not is
crucial for plate tectonic models of
the Ibero-Armorican segment of the
Variscan belt. The Léon Domain in
the Armorican Massif appears as a displaced
crustal block as it bears a resemblance
to the South Armorican Domain
of the internal Variscan belt (Le Corre
et al. 1989). In the central part of the
Léon, the amphibolite-facies Conquet-
Penze Micaschist Unit (CPMU) overlies
the high-grade Lesneven Gneiss Unit
(LGU). At the base of the LGU, a
high-pressure stage at 700°C/>13 kbar,
recorded by garnet-clinopyroxene assemblages
in eclogites was followed by a
high-temperature event at 800°C/8 kbar
with garnet and cordierite in aluminous
paragneisses. Maximal temperatures in
the upper parts of the LGU were
630°C/6 kbar. In the micaschists of
the Conquet-Penze Unit, microstructures
indicate a crystallization of garnet
and then staurolite during the development
of S1 and S2 foliations. Zoned
garnet in assemblages with staurolite
recorded prograde P–T paths from 490–
610°C at 5–8 kbar in the upper and at 6–
9 kbar in the lower parts of the CPMU. The foliation S2 was overprinted by shear bands with a top-to-
SW directed normal sense of shear, corresponding
to a dextral strike-slip movement
(Balé & Brun 1986).
A younger population of monazite with
variable Y contents displays Variscan
Th-U-Pb ages (EMP dating method)
between 340 and 300Ma. In
contrast, an older population of Cadomian
monazite at 552–517Ma is uniformly
rich in Y and was observed in
samples with only few or even no garnet.
As the 330–340Ma Saint Renan-
Kersaint granite postdates the foliations
S1 and S2 with peak metamorphic
assemblages one can conclude that
340–300Ma Variscan monazites should
postdate garnet crystallization.conferenc
Effects of active musical engagement during physical exercise on anxiety, pain and motivation in patients with chronic pain
The experience of anxiety is central to the development of chronic pain. Music listening has been previously shown to exert analgesic effects. Here we tested if an active engagement in music making is more beneficial than music listening in terms of anxiety and pain levels during physical activity that is often avoided in patients with chronic pain. We applied a music feedback paradigm that combines music making and sports exercise, and which has been previously shown to enhance mood. We explored this method as an intervention to potentially reduce anxiety in a group of patients with chronic pain (N = 24, 20 female and 4 men; age range 34 - 64, M = 51.67, SD = 6.84) and with various anxiety levels. All participants performed two conditions: one condition, Jymmin, where exercise equipment was modified with music feedback so that it could be played like musical instruments by groups of three. Second, a conventional workout condition where groups of three performed exercise on the same devices but where they listened to the same type of music passively. Participants’ levels of anxiety, mood, pain and self-efficacy were assessed with standardized psychological questionnaires before the experiment and after each condition. Results demonstrate that exercise with musical feedback reduced anxiety values in patients with chronic pain significantly as compared to conventional workout with passive music listening. There were no significant overall changes in pain, but patients with greater anxiety levels compared to those with moderate anxiety levels were observed to potentially benefit more from the music feedback intervention in terms of alleviation of pain. Furthermore, it was observed that patients during Jymmin more strongly perceived motivation through others. The observed diminishing effects of Jymmin on anxiety have a high clinical relevance, and in a longer term the therapeutic application could help to break the Anxiety Loop of Pain, reducing chronic pain. The intervention method, however, also has immediate benefits to chronic pain rehabilitation, increasing the motivation to work out, and facilitating social bonding
Impact of MiRNA-181a2 on the Clinical Course of IDH1 Wild Type Glioblastoma
Background: Recently, miRNA-181a2 could be identified as a major regulator of IDH1
expression in fat tissue. The IDH1 gene, its mutation and expression have a major impact on overall
survival in patients with glioblastoma. The presented study aimed to investigate the effect of miRNA181a2 on IDH1 expression in glioblastoma and on the prognosis of patients suffering from, for
example, a tumor. Methods: A total of 74 glioblastoma specimens were analyzed for the expression
of miRNA-181a2, acquired as fold change, using qRT-PCR. IDH1 protein expression was estimated
via mRNA quantification. Eight post mortal, non-glioma related brain tissue specimens served as
the control group. The results were correlated with relevant demographic and clinical aspects of
the cohort. A TCGA dataset was used as an independent reference. Results: MiRNA-181a2 was
significantly downregulated in tumor samples compared to the control group (p < 0.001). In the
glioblastoma cohort, 63/74 (85.1%) showed an IDH1 wild type, while 11/74 (14.9%) patients harbored
an IDH 1 mutation. In patients with IDH1 wild type glioblastoma, low miRNA-181a2 expression
correlated with a prolonged overall survival (p = 0.019), also verifiable in an independent TCGA
dataset. This correlation could not be identified for patients with an IDH1 mutation. MiRNA-181a2
expression tended to correlate inversely with IDH1 protein expression (p = 0.06). Gross total resection
of the tumor was an independent marker for a prolonged survival (p = 0.03). Conclusion: MiRNA181a2 seems to be a promising prognostic marker of selective glioblastoma patients with IDH1 wild
type characteristics. This effect may be mediated via direct regulation of IDH1 expression
Arrangement of Annexin A2 tetramer and its impact on the structure and diffusivity of supported lipid bilayers
Annexins are a family of proteins that bind to anionic phospholipid membranes
in a Ca2+-dependent manner. Annexin A2 forms heterotetramers (Anx A2t) with the
S100A10 (p11) protein dimer. The tetramer is capable of bridging phospholipid
membranes and it has been suggested to play a role in Ca2+-dependent exocytosis
and cell-cell adhesion of metastatic cells. Here, we employ x-ray reflectivity
measurements to resolve the conformation of Anx A2t upon Ca2+-dependent binding
to single supported lipid bilayers (SLBs) composed of different mixtures of
anionic (POPS) and neutral (POPC) phospholipids. Based on our results we
propose that Anx A2t binds in a side-by-side configuration, i.e., both Anx A2
monomers bind to the bilayer with the p11 dimer positioned on top. Furthermore,
we observe a strong decrease of lipid mobility upon binding of Anx A2t to SLBs
with varying POPS content. X-ray reflectivity measurements indicate that
binding of Anx A2t also increases the density of the SLB. Interestingly, in the
protein-facing leaflet of the SLB the lipid density is higher than in the
substrate-facing leaflet. This asymmetric densification of the lipid bilayer by
Anx A2t and Ca2+ might have important implications for the biochemical
mechanism of Anx A2t-induced endo- and exocytosis.Comment: 27 pages, 7 figures; supplementary material available upon request
from the author
Coulomb gap in one-dimensional disordered electronic systems
We study a one-dimensional system of spinless electrons in the presence of a
long-range Coulomb interaction (LRCI) and a random chemical potential at each
site. We first present a Tomonaga-Luttinger liquid (TLL) description of the
system. We use the bosonization technique followed by the replica trick to
average over the quenched randomness. An expression for the localization length
of the system is then obtained using the renormalization group method and also
a physical argument. We then find the density of states for different values of
the energy; we get different expressions depending on whether the energy is
larger than or smaller than the inverse of the localization length. We work in
the limit of weak disorder where the localization length is very large; at that
length scale, the LRCI has the effect of reducing the interaction parameter K
of the TLL to a value much smaller than the noninteracting value of unity.Comment: Revtex, 6 pages, no figures; discussions have been expanded in
several place
Study related factors associated with study engagement and student burnout among German university students
IntroductionStudent burnout has become a health concern in higher education systems. Its prevalence rates are high due to specific demands in this life situation. It leads not only to increased academic dropout rates but is also associated with negative health outcomes both physically and mentally. Its counterpart is study engagement, which is a positive, fulfilling, study-related attitude characterized by energy, dedication, and absorption. There has not been a systematical approach covering the demands directly posed by the academic environment itself. Additionally, academic subject fields apart from medicine and nursing sciences have been mostly neglected in regards to this research field. The aim of the study is therefore to identify contributing factors for both burnout and engagement within the academic environment in a sample of different subject fields at a German university.MethodsIn a cross-sectional study, a sample of 3,451 students of all academic subjects at a technical university in Germany has been analyzed using an online survey. Sociodemographic data, study engagement, student burnout, study satisfaction, academic workload, number of semesters and occupational liabilities have been analyzed. Binary logistic regression was used to determine the associations of burnout symptoms and study engagement.ResultsAlmost a third of the students showed frequent burnout symptoms, while 42.5% showed a high degree of study engagement with no differences in gender. Age was identified as a risk factor for frequent signs of cynicism (OR = 1.073). Study satisfaction (OR between 0.459 and 0.702), semester progression (OR = 0.959) and working moderately (OR between 0.605 and 0.637) was associated with fewer symptoms in different burnout-dimensions. Study satisfaction is positively associated with study engagement (OR = 2.676). Academic workload is positively related to both burnout (OR between 1.014 and 1.021) and study engagement (OR = 1.014).DiscussionA substantial number of students show frequent symptoms of burnout and the majority is not highly engaged. The included factors contribute to the model to various degrees and show that university-bound factors play a major role. Fostering a supportive environment is key for study engagement, health and well-being. The inclusion of further, individual factors should be a future concern in order to find and promote strategies for a healthy education system
Sustained Calcium(II)-Release to Impart Bioactivity in Hybrid Glass Scaffolds for Bone Tissue Engineering
In this study, we integrated different calcium sources into sol-gel hybrid glass scaffolds with the aim of producing implants with long-lasting calcium release while maintaining mechanical strength of the implant. Calcium(II)-release was used to introduce bioactivity to the material and eventually support implant integration into a bone tissue defect. Tetraethyl orthosilicate (TEOS) derived silica sols were cross-linked with an ethoxysilylated 4-armed macromer, pentaerythritol ethoxylate and processed into macroporous scaffolds with defined pore structure by indirect rapid prototyping. Triethyl phosphate (TEP) was shown to function as silica sol solvent. In a first approach, we investigated the integration of 1 to 10% CaCl2 in order to test the hypothesis that small CaCl2 amounts can be physically entrapped and slowly released from hybrid glass scaffolds. With 5 and 10% CaCl2 we observed an extensive burst release, whereas slightly improved release profiles were found for lower Calcium(II) contents. In contrast, introduction of melt-derived bioactive 45S5 glass microparticles (BG-MP) into the hybrid glass scaffolds as another Calcium(II) source led to an approximately linear release of Calcium(II) in Tris(hydroxymethyl)aminomethane (TRIS) buffer over 12 weeks. pH increase caused by BG-MP could be controlled by their amount integrated into the scaffolds. Compression strength remained unchanged compared to scaffolds without BG-MP. In cell culture medium as well as in simulated body fluid, we observed a rapid formation of a carbonated hydroxyapatite layer on BG-MP containing scaffolds. However, this mineral layer consumed the released Calcium(II) ions and prevented an additional increase in Calcium(II) concentration in the cell culture medium. Cell culture studies on the different scaffolds with osteoblast-like SaOS-2 cells as well as bone marrow derived mesenchymal stem cells (hMSC) did not show any advantages concerning osteogenic differentiation due to the integration of BG-MP into the scaffolds. Nonetheless, via the formation of a hydroxyapatite layer and the ability to control the pH increase, we speculate that implant integration in vivo and bone regeneration may benefit from this concept
Extrusion-Printing of Multi-Channeled Two-Component Hydrogel Constructs from Gelatinous Peptides and Anhydride-Containing Oligomers
The performance of artificial nerve guidance conduits (NGC) in peripheral nerve regeneration can be improved by providing structures with multiple small channels instead of a single wide lumen. 3D-printing is a strategy to access such multi-channeled structures in a defined and reproducible way. This study explores extrusion-based 3D-printing of two-component hydrogels from a single cartridge printhead into multi-channeled structures under aseptic conditions. The gels are based on a platform of synthetic, anhydride-containing oligomers for cross-linking of gelatinous peptides. Stable constructs with continuous small channels and a variety of footprints and sizes were successfully generated from formulations containing either an organic or inorganic gelation base. The adjustability of the system was investigated by varying the cross-linking oligomer and substituting the gelation bases controlling the cross-linking kinetics. Formulations with organic N-methyl-piperidin-3-ol and inorganic K2HPO4 yielded hydrogels with comparable properties after manual processing and extrusion-based 3D-printing. The slower reaction kinetics of formulations with K2HPO4 can be beneficial for extending the time frame for printing. The two-component hydrogels displayed both slow hydrolytic and activity-dependent enzymatic degradability. Together with satisfying in vitro cell proliferation data, these results indicate the suitability of our cross-linked hydrogels as multi-channeled NGC for enhanced peripheral nerve regeneration
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