Preparation, Characterization, and Properties of Polyurethane-Grafted Multiwalled Carbon Nanotubes and Derived Polyurethane Nanocomposites

We incorporated hydroxyl groups into the polyurethane backbone and then used the “grafting to” approach to functionalize the multiwalled carbon nanotubes (MWNTs) via the esterification reaction between MWNTs and segmented polyurethanes (PUs). X-ray photoelectron spectroscopy (XPS) spectra showed that the sidewalls of MWNTs had been functionalized with acid treatment, and the amount of COOH increased with increasing acid treatment time. FTIR spectra further confirmed that PU was covalently attached to the sidewalls of MWNTs. The functionalized acid amount and the grafted PU amount were determined by thermogravimetric analyses (TGAs). Comparative studies based on SEM images of the PU-functionalized and chemically defunctionalized MWNT samples also revealed the covalent coating character. Dynamic mechanical analysis (DMA) of nanocomposite films prepared from PU and PU-functionalized MWNTs showed enhanced mechanical properties and increased soft segment . Tensile properties indicated that PU-functionalized MWNTs were effective reinforcing fillers for the polyurethane matrix

Serotonin receptor HTR6-mediated mTORC1 signaling regulates dietary restriction-induced memory enhancement

Dietary restriction (DR; sometimes called calorie restriction) has profound beneficial effects on physiological, psychological, and behavioral outcomes in animals and in humans. We have explored the molecular mechanism of DR-induced memory enhancement and demonstrate that dietary tryptophan-a precursor amino acid for serotonin biosynthesis in the brain-and serotonin receptor 5-hydroxytryptamine receptor 6 (HTR6) are crucial in mediating this process. We show that HTR6 inactivation diminishes DR-induced neurological alterations, including reduced dendritic complexity, increased spine density, and enhanced long-term potentiation (LTP) in hippocampal neurons. Moreover, we find that HTR6-mediated mechanistic target of rapamycin complex 1 (mTORC1) signaling is involved in DR-induced memory improvement. Our results suggest that the HTR6-mediated mTORC1 pathway may function as a nutrient sensor in hippocampal neurons to couple memory performance to dietary intake

Adventitial SCA-1+ progenitor cell gene sequencing reveals the mechanisms of cell migration in response to hyperlipidemia

Adventitial progenitor cells, including SCA-1+ and mesenchymal stem cells, are believed to be important in vascular remodeling. It has been shown that SCA-1+ progenitor cells are involved in neointimal hyperplasia of vein grafts, but little is known concerning their involvement in hyperlipidemia-induced atherosclerosis. We employed single-cell sequencing technology on primary adventitial mouse SCA-1+ cells from wild-type and atherosclerotic-prone (ApoE-deficient) mice and found that a group of genes controlling cell migration and matrix protein degradation was highly altered. Adventitial progenitors from ApoE-deficient mice displayed an augmented migratory potential both in vitro and in vivo. This increased migratory ability was mimicked by lipid loading to SCA-1+ cells. Furthermore, we show that lipid loading increased miRNA-29b expression and induced sirtuin-1 and matrix metalloproteinase-9 levels to promote cell migration. These results provide direct evidence that blood cholesterol levels influence vascular progenitor cell function, which could be a potential target cell for treatment of vascular disease

All-frequency precomputed radiance transfer using spherical radial basis functions and clustered tensor approximation

This paper introduces a new data representation and compression technique for precomputed radiance transfer (PRT). The light transfer functions and light sources are modeled with spherical radial basis functions (SRBFs). A SRBF is a rotation-invariant function that depends on the geodesic distance between two points on the unit sphere. Rotating functions in SRBF representation is as straightforward as rotating the centers of SRBFs. Moreover, highfrequency signals are handled by adjusting the bandwidth parameters of SRBFs. To exploit inter-vertex coherence, the light transfer functions are further classified iteratively into disjoint clusters, and tensor approximation is applied within each cluster. Compared with previous methods, the proposed approach enables real-time rendering with comparable quality under high-frequency lighting environments. The data storage is also more compact than previous all-frequency PRT algorithms. CR Categories: I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism—Color, shading, shadowing, and texture; G.1.2 [Numerical Analysis]: Approximation—Special function approximations; E.4 [Coding and Information Theory]: Data compaction and compressio

Surface passivation of AZOY/n-Si interface of heterojunction solar cells with NH4F solution treatment

This study reports the fabrication of n-type aluminum- and yttrium-codoped zinc oxide (AZOY) on n-Si (AZOY/n-Si) heterojunction solar cells (HJSCs) by using RF magnetron sputtering at various working pressure. AZOY thin films deposited on glass and n-Si substrates at various working pressure were evaluated for optoelectrical properties and performance. At a working pressure of 3 mTorr, the AZOY films showed the lowest resistivity of 8.11 × 10 ^–3 Ωcm and visible transmittance (400–800 nm) of 84.64%, and AZOY/n-Si HJSCs achieved a high conversion efficiency of 11.83% (V _oc : 498 mV, J _sc : 35.89 mAcm ^−2 , and FF: 0.662). Repeating the optimal working pressure, the n-Si substrate was immersed in ammonium fluoride (NH _4 F) solution to improve the AZOY/n-Si interface state. The fluorine atom had the strongest electron negativity for effective passivation of the silicon dangling bond, and the device’s performance was able to further increase conversion efficiency to 12.64% (V _oc : 523mV, J _sc : 36.79 mAcm ^−2 , and FF: 0.657). Moreover, NH _4 F solution treatment of the silicon surface can increase the thinness of the SiO _x layer from 1.27 to 0.79 nm and reduce the interface state density from 8.59 × 10 ^11 to 1.13 × 10 ^11 cm ^2