Contralaterally transplanted human embryonic stem cell-derived neural precursor cells (ENStem-A) migrate and improve brain functions in stroke-damaged rats

The transplantation of neural precursor cells (NPCs) is known to be a promising approach to ameliorating behavioral deficits after stroke in a rodent model of middle cerebral artery occlusion (MCAo). Previous studies have shown that transplanted NPCs migrate toward the infarct region, survive and differentiate into mature neurons to some extent. However, the spatiotemporal dynamics of NPC migration following transplantation into stroke animals have yet to be elucidated. In this study, we investigated the fates of human embryonic stem cell (hESC)-derived NPCs (ENStem-A) for 8 weeks following transplantation into the side contralateral to the infarct region using 7.0T animal magnetic resonance imaging (MRI). T2- and T2*-weighted MRI analyses indicated that the migrating cells were clearly detectable at the infarct boundary zone by 1 week, and the intensity of the MRI signals robustly increased within 4 weeks after transplantation. Afterwards, the signals were slightly increased or unchanged. At 8 weeks, we performed Prussian blue staining and immunohistochemical staining using human-specific markers, and found that high percentages of transplanted cells migrated to the infarct boundary. Most of these cells were CXCR4-positive. We also observed that the migrating cells expressed markers for various stages of neural differentiation, including Nestin, Tuj1, NeuN, TH, DARPP-32 and SV38, indicating that the transplanted cells may partially contribute to the reconstruction of the damaged neural tissues after stroke. Interestingly, we found that the extent of gliosis (glial fibrillary acidic protein-positive cells) and apoptosis (TUNEL-positive cells) were significantly decreased in the cell-transplanted group, suggesting that hESC-NPCs have a positive role in reducing glia scar formation and cell death after stroke. No tumors formed in our study. We also performed various behavioral tests, including rotarod, stepping and modified neurological severity score tests, and found that the transplanted animals exhibited significant improvements in sensorimotor functions during the 8 weeks after transplantation. Taken together, these results strongly suggest that hESC-NPCs have the capacity to migrate to the infarct region, form neural tissues efficiently and contribute to behavioral recovery in a rodent model of ischemic stroke.     

Modeling Diffusion in Foamed Polymer Nanocomposites

Two‐way multicomponent diffusion processes in polymeric nanocomposite foams, where the condensed phase is nanoscopically reinforced with impermeable fillers, are investigated. The diffusion process involves simultaneous outward permeation of the components of the dispersed gas phase and inward diffusion of atmospheric air. The transient variation in thermal conductivity of foam is used as the macroscopic property to track the compositional variations of the dispersed gases due to the diffusion process. In the continuum approach adopted, the unsteady‐state diffusion process is combined with tortuosity theory. The simulations conducted at ambient temperature reveal distinct regimes of diffusion processes in the nanocomposite foams owing to the reduction in the gas‐transport rate induced by nanofillers. Simulations at a higher temperature are also conducted and the predictions are compared with experimentally determined thermal conductivities under accelerated diffusion conditions for polyurethane foams reinforced with clay nanoplatelets of varying individual lamellar dimensions. Intermittent measurements of foam thermal conductivity are performed while the accelerated diffusion proceeded. The predictions under accelerated diffusion conditions show good agreement with experimentally measured thermal conductivities for nanocomposite foams reinforced with low and medium aspect‐ratios fillers. The model shows higher deviations for foams with fillers that have a high aspect ratio.     

Helical Biphenyl Bisazo Polyurethane: Preparation,Characterization and Analysis of Polymeric Thermo-Optic Switch

The bisazo chromophore molecule (CAAPM) and helical biphenyl bisazo polyurethane (HBBPU) were synthesized. The structures of CAAPM and HBBPU were characterized by FT-IR and UV-vis spectroscopic techniques. The measurements of refractive index and thermo-optic coefficient (dn/dT) of HBBPU were demonstrated at different wavelengths and different temperatures by the ATR technique. By using CCD digital imaging devices, transmission loss of the internal waveguide was measured. The refractive index dispersions and Sellmeyer coefficients of HBBPU were obtained by the Sellmeyer equation. A Y-branched switch based on the thermo-optic effect was proposed and the performance of the switch was simulated. With a branching angle of 0.143° and the FD-BPM method, the result showed that the power consumption of the thermo-optic switch could be only 3.6 mW, and the response time of the switch could reach about 8 ms. This is a significant improvement in reducing power consumption compared with the normal Y-branched polymer thermo-optic switch.     

Application of poly(vinylphenyltrimethylammonium tribromide) resin as an efficient polymeric brominating agent in the α-bromination and α-bromoacetalization of acetophenones

The applications of a new supported tribromide reagent based on poly(vinylbenzyltrimethylammonium hydroxide) resin (Amberlite 717) were reported. This supported tribromide resin was used directly in α-bromination and α-bromoacetalization of acetophenones without any other catalyst under mild conditions. The effects of solvents and the amount of the supported tribromide resin on the reactions were investigated. Under the optimal conditions, most of α-bromo and α-bromoacetal of acetophenones were selectively obtained in excellent yields.     

A Facile Preparation of the Co3O4 Villiform Nanostructure

A Co₃O₄ villiform nanostructure was prepared by the aid of the cobalt oxalate precursor and characterized with x-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and UV-vis spectrum. It is found that the villiform structure obtained consists of Co₃O₄ nanorods with diameters of 50–80 nm. Moreover, the UV-vis absorptions of the villiform Co₃O₄ show the apparent blue shifts by comparison with the bulk Co₃O₄, indicating a quantum size effect similar to the free Co₃O₄ nanoparticles.     

Synthesis of AA-MMA Block Copolymer by RAFT Polymerization and Used as Emulsifier cum Macroinitiator and Its Influence on the Film Properties

Blocked copolymer of acrylic acid-methyl methacrylate with controlled molecular architecture were prepared by reversible addition chain fragmentation polymerization and were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (¹H NMR), and gel permeation chromatography (GPC) for structural evaluation. The neutralized copolymers were evaluated for the critical micelle concentration (CMC), hydrophilic lipophilic balance (HLB) and were utilized as polymeric emulsifier cum macro RAFT initiator for the synthesis of acrylic binder. The structure properties of the emulsifier were evaluated correlating with the film properties.     

Nanoparticle Halos Mechanism in Stabilizing of Colloidal Suspensions: Polymeric Binder and Dispersant Effects

Dispersion behavior of colloidal Al₂O₃ aqueous suspensions was investigated in the presence of highly charged CeO₂ nanoparticles and polymeric additives. It was found that among the investigated parameters, ceria nanoparticles concentration had the highest significant effect on the stability of Al₂O₃-CeO₂ suspensions. However, the low influence of dispersant concentration may be due to significant role of ceria nanoparticles stabilizing alumina microspheres by “nanoparticle halo” formation. The stabilization of the bidispersed suspensions was also evidenced by scanning electron microscopy and elemental analysis of the sediment layers after three weeks.     

Effect of Precursor Drying Process on the Properties of LiFePO4/C Composite with Low Carbon Content

<正>Properties of two LiFePO_4/C composites with low carbon content synthesized from precursors dried by spray drying and blast drying are investigated by scanning electron microscopy, X-ray diffraction, Raman spectroscopy and electrochemical measurements. The two samples have a different morphology and particle size, while the structure of LiFePO_4 is unaffected. The LiFePO_4/C composite prepared from the precursor dried by blast drying has a much lower surface resistance and a much better rate capability because the deposited carbon is more graphite-like and more conductive. The cycling performance is also much better for the LiFePO_4/C composite prepared from the precursor dried by blast drying because only a slight impedance growth is involved upon cycling. These results suggest that the precursor drying process has a significant impact on the properties of LiFePO_4/C composite, and its effect is highly dependent on the carbon content.     

Preparation of single-hole hollow polymer nanospheres by raspberry-like template method

Single-hole hollow polymer nanospheres were fabricated by raspberry-like template method using "graft-from" strategy through atom transfer radical polymerization (ATRP). Nanometer-sized silica spheres were covalently attached onto the surfaces of micrometer-sized silica spheres. Crosslinked polymer shells on the nano-sized spheres outside the attached area were formed by "graft-from" strategy through ATRP. After removal of the silica cores, single-hole hollow crosslinked polymer nanospheres were obtained. In this strategy, most of ATRP monomers may be used and thus many functional groups can be easily incorporated into the single-hole hollow crosslinked polymer nanospheres.     

Synthesis and thermal properties of a new styryl-functionalized pentafulvene glassy carbon precursor

The first preparation of a styryl-functionalized aryl pentafulvene 4 was carried out. In the crystal structure of 4, the packing of fulvene molecules results in the shortest intermolecular contacts between aligned vinyl groups. Thermal reactivity studies of 4 (DSC and TGA, under N₂) revealed a small difference between the melting point (120 °C) and the T_onset for cross-linking (125 °C), and provided strong evidence for the production of a network material (net4) due to reactivity of the attached styryl group. Pyrolysis of net4 under N₂ gave a glassy carbon product in low yield as revealed by powder X-ray and TGA analyses (carbon yield (TGA) of 38% (900 °C)).