2,487 research outputs found
Piezomorphic materials
The development of stress-induced morphing materials which are described as piezomorphic materials is reported. The development of a piezomorphic material is achieved by introducing spatial dependency into the compliance matrix describing the elastic response of a material capable of undergoing large strain deformation. In other words, it is necessary to produce an elastically gradient material. This is achieved through modification of the microstructure of the compliant material to display gradient topology. Examples of polymeric (polyurethane) foam and microporous polymer (expanded polytetrafluoroethylene) piezomorphic materials are presented here. These materials open up new morphing applications where dramatic shape changes can be triggered by mechanical stress
Neutrino decay as a possible interpretation to the MiniBooNE observation with unparticle scenario
In a new measurement on neutrino oscillation , the
MiniBooNE Collaboration observes an excess of electron-like events at low
energy and the phenomenon may demand an explanation which obviously is beyond
the oscillation picuture. We propose that heavier neutrino decaying
into a lighter one via the transition process
where denotes any light products, could be a natural mechanism. The
theoretical model we employ here is the unparticle scenario established by
Georgi. We have studied two particular modes \nu_\mu\to \nu_e+\Un and
. Unfortunately, the number coming out from
the computation is too small to explain the observation. Moreover, our results
are consistent with the cosmology constraint on the neutrino lifetime and the
theoretical estimation made by other groups, therefore we can conclude that
even though neutrino decay seems plausible in this case, it indeed cannot be
the source of the peak at lower energy observed by the MiniBooNE collaboration
and there should be other mechanisms responsible for the phenomenon.Comment: 14 pages, conclusions are changed; published version for EPJ
Strong and Electromagnetic Decays of X(1835) as a Baryonium State
With the assumption that the recently observed X(1835) is a baryonium state
we have studied the strong decays of and the electromagnetic decay of in the framework of effective Lagrangian formalism. In the present
investigation we have included the contributions from the iso-singlet light
scalar resonances but we have not included the isospin violating effect. Our
result for the strong decay of is
smaller than the observed data. The decay width for the radiative decay of
is consistent with the assumption that it decays through
the glueball. In addition, the width for the strong decay of is larger than that of the strong decay of due to the large phase space and coupling constant
. From our investigation, it is not possible to interpret
X(1835) as a baryonium.Comment: Corrected typo
Atomistic insights into the origin of high‐performance thermoelectric response in hybrid perovskites
Due to their tantalizing prospect of heat-electricity interconversion, hybrid organic-inorganic perovskites have sparked considerable research interests recently. Nevertheless, understanding their complex interplay between the macroscopic properties, nonintuitive transport processes, and basic chemical structures still remains far from completion, although it plays a fundamental role in systematic materials development. On the basis of multiscale first-principles calculations, this understanding is herein advanced by establishing a comprehensive picture consisting of atomic and charge dynamics. It is unveiled that the ultralow room-temperature lattice thermal conductivity (≈0.20 W m-1 K-1 ) of hybrid perovskites is critical to their decent thermoelectric figure of merit (≈0.34), and such phonon-glass behavior stems from not only the inherent softness but also the strong anharmonicity. It is identified that the 3D electrostatic interaction and hydrogen-bonded networks between the PbI3- cage and embedded cations result in the strongly coupled motions of inorganic framework and cation, giving rise to their high degree of anharmonicity. Furthermore, such coupled motions bring about low-frequency optical vibrational modes, which leads to the dominant role of electron scattering with optical phonons in charge transport. It is expected that these new atomistic-level insights offer a standing point where the performance of thermoelectric perovskites can be further enhanced
Single production of the vector-like top quark in the littlest Higgs model at TeV energy colliders
The new colored vector-like heavy fermion is a crucial prediction in
little Higgs models, which plays a key role in breaking the electroweak
symmetry. The littlest Higgs model is the most economical one among various
little Higgs models. In the context of the littlest Higgs model, we study
single production of the new heavy vector-like quark via
collisions and discuss the possibility of detecting this new particle in the
TeV energy collider(LC). We find that the production cross section
can vary in a wide range() in most parameter spaces. For the
favorable parameter spaces, the possible signals of the vector-like top quark
can be detected via collisions in future experiment with
and .Comment: 10 pages,3 figure
Reducing the communication complexity with quantum entanglement
We propose a probabilistic two-party communication complexity scenario with a
prior nonmaximally entangled state, which results in less communication than
that is required with only classical random correlations. A simple all-optical
implementation of this protocol is presented and demonstrates our conclusion.Comment: 4 Pages, 2 Figure
Excess Imidacloprid Exposure Causes the Heart Tube Malformation of Chick Embryos
As a neonicotinoid pesticide, imidacloprid is widely used to control sucking insects on agricultural planting and fleas on domestic animals. However, the extent to which imidacloprid exposure has an influence on cardiogensis in early embryogenesis is still poorly understood. In vertebrates, the heart is the first organ to be formed. In this study to address whether or not imidacloprid exposure affects early heart development, the early chick embryo has been used as an experimental model because of the accessibility of chick embryo at its early developmental stage. The results demonstrate that exposure of the early chick embryo to imidacloprid caused malformation of heart tube. Furthermore,the data reveal that down-regulation of GATA4, Nkx2.5 and BMP4 and up-regulation of Wnt3a led to aberrant cardiomyocyte differentiation. In addition, imidacloprid exposure interfered with basement membrane (BM) breakdown, E-cadherin/Laminin expression and mesoderm formation during the epithelial-mesenchymal transition (EMT) in gastrula chick embryos. Finally, the DiI-labeled cell migration trajectory indicated that imidacloprid restricted the cell migration of cardiac progenitors to primary heart field in gastrula chick embryos. A similar observation was also obtained from the cell migration assay of scratch wounds in vitro. Additionally, imidacloprid exposure negatively affected the cytoskeleton structure and expression of corresponding adhesion molecules. Taken together, these results reveal that the improper EMT, cardiac progenitor migration and differentiation are responsible for imidacloprid exposure-induced malformation of heart tube during chick embryo development
Gradient microfluidics enables rapid bacterial growth inhibition testing
Bacterial growth inhibition tests have become a standard measure of the adverse effects of inhibitors for a wide range of applications, such as toxicity testing in the medical and environmental sciences. However, conventional well-plate formats for these tests are laborious and provide limited information (often being restricted to an end-point assay). In this study, we have developed a microfluidic system that enables fast quantification of the effect of an inhibitor on bacteria growth and survival, within a single experiment. This format offers a unique combination of advantages, including long-term continuous flow culture, generation of concentration gradients, and single cell morphology tracking. Using Escherichia coli and the inhibitor amoxicillin as one model system, we show excellent agreement between an on-chip single cell-based assay and conventional methods to obtain quantitative measures of antibiotic inhibition (for example, minimum inhibition concentration). Furthermore, we show that our methods can provide additional information, over and above that of the standard well-plate assay, including kinetic information on growth inhibition and measurements of bacterial morphological dynamics over a wide range of inhibitor concentrations. Finally, using a second model system, we show that this chip-based systems does not require the bacteria to be labeled and is well suited for the study of naturally occurring species. We illustrate this using Nitrosomonas europaea, an environmentally important bacteria, and show that the chip system can lead to a significant reduction in the period required for growth and inhibition measurements (<4 days, compared to weeks in a culture flask)
Identification of S100A8-correlated genes for prediction of disease progression in non-muscle invasive bladder cancer
<p>Abstract</p> <p>Background</p> <p><it>S100 calcium binding protein A8 </it>(<it>S100A8</it>) has been implicated as a prognostic indicator in several types of cancer. However, previous studies are limited in their ability to predict the clinical behavior of the cancer. Here, we sought to identify a molecular signature based on <it>S100A8 </it>expression and to assess its usefulness as a prognostic indicator of disease progression in non-muscle invasive bladder cancer (NMIBC).</p> <p>Methods</p> <p>We used 103 primary NMIBC specimens for microarray gene expression profiling. The median follow-up period for all patients was 57.6 months (range: 3.2 to 137.0 months). Various statistical methods, including the leave-one-out cross validation method, were applied to identify a gene expression signature able to predict the likelihood of progression. The prognostic value of the gene expression signature was validated in an independent cohort (n = 302).</p> <p>Results</p> <p>Kaplan-Meier estimates revealed significant differences in disease progression associated with the expression signature of <it>S100A8</it>-correlated genes (log-rank test, <it>P </it>< 0.001). Multivariate Cox regression analysis revealed that the expression signature of <it>S100A8</it>-correlated genes was a strong predictor of disease progression (hazard ratio = 15.225, 95% confidence interval = 1.746 to 133.52, <it>P </it>= 0.014). We validated our results in an independent cohort and confirmed that this signature produced consistent prediction patterns. Finally, gene network analyses of the signature revealed that <it>S100A8</it>, <it>IL1B</it>, and <it>S100A9 </it>could be important mediators of the progression of NMIBC.</p> <p>Conclusions</p> <p>The prognostic molecular signature defined by <it>S100A8</it>-correlated genes represents a promising diagnostic tool for the identification of NMIBC patients that have a high risk of progression to muscle invasive bladder cancer.</p
The Tyrosine Kinase c-Src Directly Mediates Growth Factor-Induced Notch-1 and Furin Interaction and Notch-1 Activation in Pancreatic Cancer Cells
The proteolytic activity of Furin responsible for processing full length Notch-1 (p300) plays a critical role in Notch signaling. The amplitude and duration of Notch activity can be regulated at various points in the pathway, but there has been no report regarding regulation of the Notch-1-Furin interaction, despite its importance. In the present study, we found that the Notch-1-Furin interaction is regulated by the non-receptor tyrosine kinase, c-Src. c-Src and Notch-1 are physically associated, and this association is responsible for Notch-1 processing and activation. We also found that growth factor TGF-α, an EGFR ligand, and PDGF-BB, a PDGFR ligand, induce the Notch-1-Furin interaction mediated by c-Src. Our results support three new and provocative conclusions: (1) The association between Notch-1 and Furin is a well-regulated process; (2) Extracellular growth factor signals regulate this interaction, which is mediated by c-Src; (3) There is cross-talk between the plasma growth factor receptor-c-Src and Notch pathways. Co-localization of Notch-1 and c-Src was confirmed in xenograft tumor tissues and in the tissues of pancreatic cancer patients. Our findings have implications for the mechanism by which the Notch and growth factor receptor-c-Src signaling pathways regulate carcinogenesis and cancer cell growth
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