Bulk Polymer-Derived Ceramic Composites of Graphene Oxide

Bulk polymer-derived ceramic (PDC) composites of SiCO with an embedded graphene network were produced using graphene-coated poly­(vinyl alcohol) (PVA) foams as templates. The pyrolysis of green bodies containing cross-linked polysiloxane, PVA foams, and graphene oxide (GO) resulted in the decomposition of PVA foams, compression of GO layers, and formation of graphitic domains adjacent to GO within the SiCO composite, leading to SiCO composites with an embedded graphene network. The SiCO/GO composite, with about 1.5% GO in the ceramic matrix, offered an increase in the electrical conductivity by more than 4 orders of magnitude compared to that of pure SiCO ceramics. Additionally, the unique graphene network in the SiCO demonstrated a drop in the observed thermal conductivity of the composite (∼0.8 W m^–1 K^–1). Young’s modulus of the as-fabricated SiCO/GO composites was found to be around 210 MPa, which is notably higher than the reported values for similar composites fabricated from only ceramic precursors and PVA foams. The present approach demonstrates a facile and cost-effective method of producing bulk PDC composites with high electrical conductivity, good thermal stability, and low thermal conductivity

Bulk Polymer-Derived Ceramic Composites of Graphene Oxide

Bulk polymer-derived ceramic (PDC) composites of SiCO with an embedded graphene network were produced using graphene-coated poly­(vinyl alcohol) (PVA) foams as templates. The pyrolysis of green bodies containing cross-linked polysiloxane, PVA foams, and graphene oxide (GO) resulted in the decomposition of PVA foams, compression of GO layers, and formation of graphitic domains adjacent to GO within the SiCO composite, leading to SiCO composites with an embedded graphene network. The SiCO/GO composite, with about 1.5% GO in the ceramic matrix, offered an increase in the electrical conductivity by more than 4 orders of magnitude compared to that of pure SiCO ceramics. Additionally, the unique graphene network in the SiCO demonstrated a drop in the observed thermal conductivity of the composite (∼0.8 W m^–1 K^–1). Young’s modulus of the as-fabricated SiCO/GO composites was found to be around 210 MPa, which is notably higher than the reported values for similar composites fabricated from only ceramic precursors and PVA foams. The present approach demonstrates a facile and cost-effective method of producing bulk PDC composites with high electrical conductivity, good thermal stability, and low thermal conductivity

Structural Evolution of Polymer-Derived Amorphous SiBCN Ceramics at High Temperature

Polymer-derived amorphous SiBCN ceramics are synthesized through a simple dehydrocoupling and hydroboration reaction of an oligosilazane containing amine and vinyl groups and BH3·Me2S, followed by pyrolysis. Two types of ceramics, denoted as Si2B1 and Si4B1, are produced from preceramic polymers with Si/B ratios of 2/1 and 4/1, respectively. The structural evolution of these ceramics with respect to the pyrolysis temperature and boron concentration is investigated using solid-state NMR, Raman, and EPR spectroscopy. Solid-state NMR suggests the presence of three major components in the ceramics: (i) hexagonal boron nitride (h-BN), (ii) turbostratic boron nitride (t-BN), and (iii) BN2C groups. Increasing pyrolysis temperature leads to the transformation of BN2C groups into BN3 and “free” carbon. A thermodynamic model is proposed to explain such transformation. Raman spectroscopy measurements reveal that the concentration of the “free” carbon cluster decreases with increasing pyrolysis temperature, and Si4B1 contains more “free” carbon cluster than Si2B1. EPR studies reveal that the carbon (C)-dangling bond content also decreases with increasing pyrolysis temperature. It appears that the complete decomposition of the metastable BN2C groups to the BN3 groups and the “free” carbon affects the crystallization of SiBCN, which leads to Si4B1 ceramics crystallized at 1500 °C, whereas Si2B1 ceramics crystallized at 1600 °C

Fabrication of Organic Field Effect Transistor by Directly Grown Poly(3 Hexylthiophene) Crystalline Nanowires on Carbon Nanotube Aligned Array Electrode

We fabricated organic field effect transistors (OFETs) by directly growing poly (3-hexylthiophne) (P3HT) crystalline nanowires on solution processed aligned array single walled carbon nanotubes (SWNT) interdigitated electrodes by exploiting strong π−π interaction for both efficient charge injection and transport. We also compared the device properties of OFETs using SWNT electrodes with control OFETs of P3HT nanowires deposited on gold electrodes. Electron transport measurements on 28 devices showed that, compared to the OFETs with gold electrodes, the OFETs with SWNT electrodes have better mobility and better current on−off ratio with a maximum of 0.13 cm2/(V s) and 3.1 × 105, respectively. The improved device characteristics with SWNT electrodes were also demonstrated by the improved charge injection and the absence of short channel effect, which was dominant in gold electrode OFETs. The enhancement of the device performance can be attributed to the improved interfacial contact between SWNT electrodes and the crystalline P3HT nanowires as well as the improved morphology of P3HT due to one-dimensional crystalline nanowire structure

Rbm46 downregulates the mRNA level of <i>β-Catenin</i>.

(A) pPE-E14 cells (Control) and pPy-Rbm46 cells were lysed and subjected to western blot with the indicated antibodies. (B) RT-PCR analysis of the indicated mRNA levels in pPE-E14 cells (Control) and pPy-Rbm46 cells. Experiment was performed in triplicate. Error bars showed the standard deviation. **, pRbm46 shRNA cells were lysed and subjected to western blot with the indicated antibodies. (D) RT-PCR analysis of the indicated mRNA levels in Non-silence cells and Rbm46 shRNA cells. Experiment was performed in triplicate. Error bars showed the standard deviation. ***, pRbm46 RNAi. Luciferase activities were measured after 48 h. The Luciferase activity was normalized to the control reporter (SV40 Poly A) activity. Experiments were performed in triplicate. Error bars showed the standard deviation. ***, p<0.001; t-test for (G) and one-way ANOVA with Tukey’s post hoc test for (H).</p

Rbm46 inhibits mESC proliferation.

<p>(A) RT-PCR and Western Blot analysis of the pPy-Rbm46-E14 stable cell lines. (B) CCK-8 analysis of the proliferation rate of pPE-E14 cells and pPy-Rbm46 cells within 72 hours after seeding. Experiment was performed in triplicate. Error bars showed the standard deviation. (C) Statistics analysis of the average diameter of the colonies formed by pP-E14 cells and pPy-Rbm46 cells, respectively. Experiment was performed in triplicate. Error bars showed the standard deviation. ***, p<0.001; t-test. (D) Representative profiles of the pPE-E14 cells and pPy-Rbm46 cells by Annexin V/PI staining. (E) and (F) RT-PCR analysis of <i>Oct4</i> and <i>Rbm46</i> mRNA level at the indicated time points in E14 cells induced to undergo differentiation by removal of LIF. Experiments were performed in triplicate. Error bars showed the standard deviation.</p

Rbm46 interacts with the P-bodies.

<p>(A) pPy-Rbm26 cells which can stably express Flag-Rbm46 were lysed and subjected to FLAG immunoprecipitation, followed by MS analysis. (B) Flag-Rbm46 was transfected into E14 cells for 24 hours and were lysed and subjected to FLAG immunoprecipitation. Total RNA extracted from the eluate was subjected to RT-PCR with primers specific to <i>β-Catenin</i> and <i>Gapdh</i> (negative control). (C) Double immunofluorescence staining using antibodies against Rbm46 (red) and Pabpc1 (green) shows a clear co-localization in E14/T mESCs.</p

Controlling Poly(3-hexylthiophene) Crystal Dimension: Nanowhiskers and Nanoribbons

Controlling Poly(3-hexylthiophene) Crystal Dimension: Nanowhiskers and Nanoribbon

Stable Superhydrophobic Coatings from Polyelectrolyte Multilayers

The present study demonstrates that the superhydrophobic behavior of the lotus leaf structure can be mimicked by creating a honeycomb-like polyelectrolyte multilayer surface overcoated with silica nanoparticles. Superhydrophobicity was achieved by coating this highly textured multilayer surface with a semifluorinated silane. The surface maintains its superhydrophobic character even after extended immersion in water. The key structural elements needed to create stable, superhydrophobic coatings from polyelectrolyte multilayers are discussed

Rbm46 regulates mouse embryonic stem cell differentiation by targeting <i>β-Catenin</i> mRNA for degradation

<div><p>Embryonic stem cells (ESCs) are pluripotent cells and have the capability for differentiation into any of the three embryonic germ layers. The Wnt/<i>β-Catenin</i> pathway has been shown to play an essential role in ESC differentiation regulation. Activation of <i>β-Catenin</i> by post-translational modification has been extensively studied. However, mechanism(s) of post-transcriptional regulation of <i>β-Catenin</i> are not well defined. In this study, we report an RNA recognition motif-containing protein (RNA binding motif protein 46, RBM46) which regulates the degradation of <i>β-Catenin</i> mRNA. Our results show that Rbm46 is distributed primarily in the cytoplasm of mouse ESCs (mESCs) and is elevated during the process of ESC differentiation. In addition, overexpression of Rbm46 results in differentiation of mESCs into trophectoderm, while knock-down of <i>Rbm46</i> leads to mESC differentiation into endoderm. β-Catenin, a key effector in the Wnt pathway which has been reported to play a significant role in the regulation of ESC differentiation, is post-transcriptionally regulated by Rbm46. Our study reveals Rbm46 plays a novel role in the regulation of ESC differentiation.</p></div