95 research outputs found
Effect of Langmuir monolayer of bovine serum albumin protein on the morphology of calcium carbonate
Bovine serum albumin (BSA) Langmuir monolayer, as a model of
biomineralization-associated proteins, was used to study its effect on
regulated biomineralization of calcium carbonate. The effects of the BSA
Langmuir monolayer and the concentration of the subphase solution on the
nucleation and growth processes and morphology of the calcium carbonate crystal
were investigated. The morphology and polymorphic phase of the resulting
calcium carbonate crystals were characterized by scanning electron microscopy
(SEM) and X-ray diffraction analysis (XRD). Moreover, the interaction
mechanisms of the subphase solution with the BSA Langmuir monolayer were
discussed. It was found that BSA Langmuir monolayer could be used as a template
to successfully manipulate the polymorphic phase and crystal morphology of
calcium carbonate and had obvious influence on the oriented crystallization and
growth. The final morphology or aggregation mode of the calcite crystal was
closely dependent on the concentration of calcium bicarbonate solution. It is
expected that this research would help to better understand the mechanism of
biomineralization by revealing the interactions between protein matrices and
crystallization of calcium carbonate crystal.Comment: 4 pages, 4 figure
TREM2 Expression in Schizophrenia
TREM2 and TYROBP are causal genes for Nasu–Hakola disease (NHD), a rare autosomal recessive disease characterized by bone lesions and early-onset progressive dementia. TREM2 forms a receptor signaling complex with TYROBP, which triggers the activation of immune responses in macrophages and dendritic cells, and the functional polymorphism of TREM2 is reported to be associated with neurodegenerative disorders such as Alzheimer’s disease (AD). The objective of this study was to reveal the involvement of TYROBP and TREM2 in the pathophysiology of AD and schizophrenia. Methods: We investigated the mRNA expression level of the 2 genes in leukocytes of 26 patients with AD and 24 with schizophrenia in comparison with age-matched controls. Moreover, we performed gene association analysis between these 2 genes and schizophrenia. Results: No differences were found in TYROBP mRNA expression in patients with AD and schizophrenia; however, TREM2 mRNA expression was increased in patients with AD and schizophrenia compared with controls (P < 0.001). There were no genetic associations of either gene with schizophrenia in Japanese patients. Conclusion: TREM2 expression in leukocytes is elevated not only in AD but also in schizophrenia. Inflammatory processes involving TREM2 may occur in schizophrenia, as observed in neurocognitive disorders such as AD. TREM2 expression in leukocytes may be a novel biomarker for neurological and psychiatric disorders
RSRE: RNA structural robustness evaluator
Biological robustness, defined as the ability to maintain stable functioning in the face of various perturbations, is an important and fundamental topic in current biology, and has become a focus of numerous studies in recent years. Although structural robustness has been explored in several types of RNA molecules, the origins of robustness are still controversial. Computational analysis results are needed to make up for the lack of evidence of robustness in natural biological systems. The RNA structural robustness evaluator (RSRE) web server presented here provides a freely available online tool to quantitatively evaluate the structural robustness of RNA based on the widely accepted definition of neutrality. Several classical structure comparison methods are employed; five randomization methods are implemented to generate control sequences; sub-optimal predicted structures can be optionally utilized to mitigate the uncertainty of secondary structure prediction. With a user-friendly interface, the web application is easy to use. Intuitive illustrations are provided along with the original computational results to facilitate analysis. The RSRE will be helpful in the wide exploration of RNA structural robustness and will catalyze our understanding of RNA evolution. The RSRE web server is freely available at http://biosrv1.bmi.ac.cn/RSRE/ or http://biotech.bmi.ac.cn/RSRE/
Search for lepton flavor violation in supersymmetric models via meson decays
Considering the constraints from the experimental data on , , conversion etc., we analyze the Lepton
Flavor Violating decays in the scenarios of the minimal supersymmetric
extensions of Standard Model with seesaw Mechanism. Numerically, there is
parameter space that the LFV processes of
can reach the upper experimental
bounds, meanwhile the theoretical predictions on ,
, conversion satisfy the present experimental bounds.
For searching of new physics, Lepton Flavor Violating processes
may be more promising and effective
channels.Comment: 30 pages, 13 figure
An invisible medium for circularly polarized electromagnetic waves
We study the no reflection condition for a planar boundary between vacuum and
an isotropic chiral medium. In general chiral media, elliptically polarized
waves incident at a particular angle satisfy the no reflection condition. When
the wave impedance and wavenumber of the chiral medium are equal to the
corresponding parameters of vacuum, one of the circularly polarized waves is
transmitted to the medium without reflection or refraction for all angles of
incidence. We propose a circular polarizing beam splitter as a simple
application of the no reflection effect.Comment: 7 pages, 3 figure
Electroweak Baryogenesis and Dark Matter with an approximate R-symmetry
It is well known that R-symmetric models dramatically alleviate the SUSY
flavor and CP problems. We study particular modifications of existing
R-symmetric models which share the solution to the above problems, and have
interesting consequences for electroweak baryogenesis and the Dark Matter (DM)
content of the universe. In particular, we find that it is naturally possible
to have a strongly first-order electroweak phase transition while
simultaneously relaxing the tension with EDM experiments. The R-symmetry (and
its small breaking) implies that the gauginos (and the neutralino LSP) are
pseudo-Dirac fermions, which is relevant for both baryogenesis and DM. The
singlet superpartner of the U(1)_Y pseudo-Dirac gaugino plays a prominent role
in making the electroweak phase transition strongly first-order. The
pseudo-Dirac nature of the LSP allows it to behave similarly to a Dirac
particle during freeze-out, but like a Majorana particle for annihilation today
and in scattering against nuclei, thus being consistent with current
constraints. Assuming a standard cosmology, it is possible to simultaneously
have a strongly first-order phase transition conducive to baryogenesis and have
the LSP provide the full DM relic abundance, in part of the allowed parameter
space. However, other possibilities for DM also exist, which are discussed. It
is expected that upcoming direct DM searches as well as neutrino signals from
DM annihilation in the Sun will be sensitive to this class of models.
Interesting collider and Gravity-wave signals are also briefly discussed.Comment: 50 pages, 10 figure
Structure of Spontaneous UP and DOWN Transitions Self-Organizing in a Cortical Network Model
Synaptic plasticity is considered to play a crucial role in the experience-dependent self-organization of local cortical networks. In the absence of sensory stimuli, cerebral cortex exhibits spontaneous membrane potential transitions between an UP and a DOWN state. To reveal how cortical networks develop spontaneous activity, or conversely, how spontaneous activity structures cortical networks, we analyze the self-organization of a recurrent network model of excitatory and inhibitory neurons, which is realistic enough to replicate UP–DOWN states, with spike-timing-dependent plasticity (STDP). The individual neurons in the self-organized network exhibit a variety of temporal patterns in the two-state transitions. In addition, the model develops a feed-forward network-like structure that produces a diverse repertoire of precise sequences of the UP state. Our model shows that the self-organized activity well resembles the spontaneous activity of cortical networks if STDP is accompanied by the pruning of weak synapses. These results suggest that the two-state membrane potential transitions play an active role in structuring local cortical circuits
- …