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The fabricated surface modified boron nitride epoxy composites exhibit high thermal conductivity, superior thermal stability and good mechanical properties while retaining good electrical insulation properties.

Colloidal interactions between particles dispersed in a liquid can be suitably tailored by modifying the surface chemistry of the particles. In the case of fumed silica particles, the surface can be systematically altered from hydrophilic to hydrophobic by replacing a portion of the original silanol (Si-OH) groups by nonpolar alkyl chains. In this study, we probe the effect of surface modification of fumed silica on their rheology and microstructure in polar media. Variables of interest include the length of the tethered alkyl chain and the extent of surface coverage. For the continuous phase, we examine a range of polyether liquids comprising different architectures and molecular weights. We find that when the alkyl chains are C8 or longer, and are attached at saturation levels, a dense nonpolar surface layer is formed on each silica unit. Such particles experience strong interactions in polar media, leading to the formation of a volume-filling network (gel). We show that these interactions arise as a result of the negative free energy of mixing between the tethered chains, owing to the mismatch in chemical nature between chains and solvent. In this flocculation process van der Waals interactions between the particles play a negligible role. We also find that the greater the mismatch between particle surface and liquid, the greater the "stickiness" of the surface chains and correspondingly, the higher the elastic modulus (G′) of the fumed silica network. This leads to a unique correlation between G′ and a term comprising the parameter for the chain-solvent pair. An approximate but useful form of this correlation can be written as G′ ∼ (δs -δm) 2 where the latter expression characterizes the mismatch in solubility parameters between the surface chains (δs) and the liquid medium (δm). A. IntroductionColloidal particles are utilized in a wide variety of applications ranging from the established (e.g., coatings and printing inks) to the emerging (e.g., display devices and fiber-optic cable gels). In many of these applications, the particles are dispersed in a given liquid with the aim of suitably modifying the flow properties (rheology) of the system. The desired effects may include an increase in viscosity, as well as shear-thinning and thixotropy. In certain cases, it is intended for the particles to flocculate and form a colloidal gel that can exhibit elastic (solidlike) character. Thus, gel formation is often desirable and critical to the utilization of the colloidal system, as is the case in the present investigation.In our study we use fumed silica particles 1-3 as a gelling agent in polar organic liquids. Our interest in this class of materials stems from their potential application as composite polymer electrolytes in rechargeable lithium batteries. 4,5 For this purpose, the organic liquids envisioned for use mainly belong to the polyether family: for example, poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG). Solutions of polyether and lithium salt serve as polymer electrolytes owing to the uniqu...

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CSN6, a critical subunit of the constitutive photomorphogenesis 9 (COP9) signalosome (CSN), has received attention as a regulator of the degradation of cancer-related proteins such as p53, c-myc and c-Jun, through the ubiquitin-proteasome system, suggesting its importance in cancerogenesis. However, the biological functions and molecular mechanisms of CSN6 in glioblastoma (GBM) remain poorly understood. Here, we report that GBM tumors overexpressed CSN6 compared with normal brain tissues and that CSN6 promoted GBM cell proliferation, migration, invasion and tumorigenesis. Erlotinib, a small-molecule epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, was used to reveal that the proliferative and metastatic effects of CSN6 on GBM cells were EGFR dependent. We also found that CSN6 positively regulated EGFR stability via reduced levels of EGFR ubiquitination, thereby elevating steady expression of EGFR. In addition, this study is the first description of a novel role for the CSN6-interacting E3 ligase, CHIP (carboxyl terminus of heat-shock protein 70-interacting protein), regulating EGFR ubiquitination in cancer cells. We showed that CSN6 associated with CHIP and led to CHIP destabilization by increasing CHIP self-ubiquitination. Moreover, CSN6 decreased CHIP expression and increased EGFR expression in the tumor samples. Deregulation of this axis promoted GBM cell's proliferation and metastasis. Thus, our study provides insights into the applicability of using the CSN6-CHIP-EGFR axis as a potential therapeutic target in cancer.

Hexagonal boron nitride micro particles functionalized by γ-MPS, were used to fabricate PI/BN composites. The thermal conductivity of the composites with 40 wt% m-BN content was increased to 0.748 W m−1 K−1, 4.5 times higher than that of the pure PI.

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