2,973 research outputs found
Testing the phenomenological interacting dark energy with observational data
In order to test the possible interaction between dark energy and dark
matter, we investigate observational constraints on a phenomenological
scenario, in which the ratio between the dark energy and matter densities is
proportional to the power law case of the scale factor, . By using the Markov chain Monte Carlo method,
we constrain the phenomenological interacting dark energy model with the newly
revised data, as well as the cosmic microwave background (CMB)
observation from the 7-year Wilkinson Microwave Anisotropy Probe (WMAP7)
results, the baryonic acoustic oscillation (BAO) observation from the
spectroscopic Sloan Digital Sky Survey (SDSS) data release 7 (DR7) galaxy
sample and the type Ia supernovae (SNe Ia) from Union2 set. The best-fit values
of the model parameters are
,
, and
, which are more
stringent than previous results. These results show that the standard
CDM model without any interaction remains a good fit to the recent
observational data; however, the interaction that the energy transferring from
dark matter to dark energy is slightly favored over the interaction from dark
energy to dark matter. It is also shown that the data can give more
stringent constraints on the phenomenological interacting scenario when
combined to CMB and BAO observations, and the confidence regions of
+BAO+CMB, SNe+BAO+CMB, and +SNe+BAO+CMB combinations are consistent
with each other.Comment: 6 pages, 4 figures, 1 table. MNRAS in pres
Gap Junction Mediated miRNA Intercellular Transfer and Gene Regulation: A Novel Mechanism for Intercellular Genetic Communication
Intercellular genetic communication is an essential requirement for coordination of cell proliferation and differentiation and has an important role in many cellular processes. Gap junction channels possess large pore allowing passage of ions and small molecules between cells. MicroRNAs (miRNAs) are small regulatory RNAs that can regulate gene expression broadly. Here, we report that miRNAs can pass through gap junction channels in a connexin-dependent manner. Connexin43 (Cx43) had higher permeability, whereas Cx30 showed little permeability to miRNAs. In the tested connexin cell lines, the permeability to miRNAs demonstrated: Cx43 \u3e Cx26/30 \u3e Cx26 \u3e Cx31 \u3e Cx30 = Cx-null. However, consistent with a uniform structure of miRNAs, there was no significant difference in permeability to different miRNAs. The passage is efficient; the miRNA level in the recipient cells could be up to 30% of the donor level. Moreover, the transferred miRNA is functional and could regulate gene expression in neighboring cells. Connexin mutation and gap junctional blockers could eliminate this miRNA intercellular transfer and gene regulation. These data reveal a novel mechanism for intercellular genetic communication. Given that connexin expression is cell-specific, this connexin-dependent, miRNA intercellular genetic communication may play an important role in synchronizing and coordinating proliferation and differentiation of specific cell types during multicellular organ development
ZnO-Based Electron Transporting Layer for Perovskite Solar Cells
Recently, organic/inorganic hybrid perovskite materials, APbX3 (A = CH3NH3 or HC(NH2)2; X = I, Br or Cl), have attracted much interest for their promising application in solar cells as the light-absorbing component to their broad spectral absorption, strong light-harvesting and long exciton diffusion length. The perovskite solar cells (PSCs) can reduce the production costs and achieve high power conversion efficiency significantly compared to standard silicon cells and other thin film cells. On the other hand, ZnO based materials have been recently investigated in the PSCs devices as electron injection layers for low-temperature, low-cost and flexible devices. This chapter aims to review PSCs using ZnO materials as electron extraction layers. We will discuss the electron transmission and effect of the electron-transporting layer in PSCs and the preparation method of the ZnO. ZnO is a potential material for many applications due to their high electron mobility, transparent and various nanostructure. The ZnO was introduced into the PSCs structure to improve electron extraction efficiency. This chapter summaries the effect and parameters of PSCs based on the ZnO layer/nanostructure prepared by several methods as electron transport layers
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