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This study provides a route to prepare 4-arm star poly(methyl methacrylate) (4sPMMA)/PMMA grafted SiO2 (PMMA-g-SiO2) hybrid nanocomposites that can be used as 3D printing material and filler for dental materials. First, 4sPMMA was synthesized via atom transfer radical polymerization with low metal catalyst concentration. Modified colloidal silica nanoparticles (MCSPs) were synthesized by grafting 3-methoxypropyl trimethoxysilane (MPS) onto the surface of colloidal silica nanoparticles (CSPs) and then dispersed in the solution of methyl methacrylate monomer in dioxane. The mixture of 4sPMMA and MCSPs solutions was degassed and replaced in an oil bath at 70–75°C; the reaction was continued with α,α′-azobis(isobutyronitrile) as an initiator for 24 h to form 4sPMMA/PMMA-g-SiO2 hybrid nanocomposites. Viscosity measurement showed that viscosity of the hybrid was increased with increasing MPS loading used in modification of CSPs, which verified that PMMA had been grafted onto MCSPs. Fourier transform infrared spectra of the hybrid nanocomposites demonstrated the strong molecular interaction between MCSPs and polymer matrix, and 1H NMR spectra confirmed the formation of PMMA-g-SiO2. Field emission scanning electron microscopy and transmission electron microscopy images revealed that MCSPs were well dispersed in polymer matrix with the size of about 20–30 nm. Thermal stability of the hybrid nanocomposites was improved compared with PMMA made from free radical polymerization.

Blood and urine were collected for determination of biochemical parameters. Histological changes in the aorta and kidney were examined. At the end of the experiment, blood glucose, HbA1c and microalbumin showed at higher level. All of the high fat diet plus STZ injection rats exhibit remarkable lesions and plaque in their aorta representing damage to large blood vessels. However, they demonstrated features of different glomerulopathy. Rats suffered from hyperglycemia in whole studying time exhibit global glomerulosclerosis, hyaline arteriosclerosis and glomerular nodule which are comparable with characteristics observed in later stage of human nephropathy. The rest diabetic rats demonstrated features of mild nephropathy corresponding with a former stage of kidney disease.

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The solvent extraction of zinc(II) in 0.1 mol dm-3 sodium chloride solutions with 1-naphthoic acid (HA) into chloroform was measured in the absence and presence of tetrabutylammonium ions (tba+) or trioctylphosphine oxide (TOPO). The extraction of zinc(II) with 1-naphthoic acid was rather poor and the extracted species were in the form of ZnA2 and ZnA2(HA)2 when the metal concentration in the organic phase was lower than 3X105 mol dm-3. However, the polymerized species, ZnnA2n(HA)m, were also extracted when zinc(II) concentration in the organic phase was higher than that value. The addition of tba+ or TOPO enhanced the extraction of zinc(II) 1-naphthoate. This was explained in terms of the extraction of tba+ZnA3-or ZnA2TOPO species. Thus 1-naphthoic acid was found to be an effective extractant for zinc(II) only in the presence of bulky cations or solvating type extractants. We considered the reason why only the monomeric zinc(II) species of the ternary complex or the TOPO adduct was extracted.Keywords Solvent extraction, zinc(II),1-naphthoic acid, tetrabutylammonium ion, trioctylphosphine oxide In a previous papers, one of us reported that zinc(II) can be extracted with several aliphatic carboxylic acids into carbon tetrachloride, although the extractions were not very effective. However, when quinoline was added into these liquid-liquid systems, the extraction was very much enhanced. It was reported other papers that the extraction of europium(III) with 1-naphthoic acid into chloroform was enhanced by an addition of tributylphosphate (TBP)2 or trioctylphosphine oxide (TOPO).3 The extraction of europium(III) in the absence of such solvating type extractants was not very effective and very complicated: both the EuA3HA and the polynuclear species Eu2A6(HA)2 were extracted. However, extraction was very much enhanced by an addition of TOPO due to the formation of adduct complexes, both EuA3TOPO and EuA3(TOPO)2. Moreover, the addition of TOPO prevented formation of polynuclear species. An addition of tetrabutylammonium ions (tba+) enhanced the extraction of europium(III) with 1-naphthoic acid due to the extraction of anionic complex as ion-pairs, EuA4-tba+, but no extraction of anionic polynuclear species was found even when the metal concentration was high.In the present research, the extraction of zinc(II) with 1-naphthoic acid into chloroform was studied in the absence and presence of tba+ or TOPO and the effect of these reagents on the extraction is considered. StatisticalAll the chemical species in the organic phase are denoted by the subscript "org", and those in the aqueous phase are shown without any subscript. The volumes of the two liquid phases are assumed to be the same. The data can be treated in a similar manner to that described previously.3The concentration of the extractant anion (A-) can be written as

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Here we report a facile approach to enhance the dispersibility of ethylene vinyl acetate copolymer (EVA)/silica nanocomposites (for the EVA/silica nanocomposites and interaction between silica nanoparticles (nanosilica) and EVA by adding EVA-g-acrylic acid (EVAgAA) as a compatibilizer, which was formed by grafting acrylic acid onto EVA chains with the aid of dicumyl peroxide). The above nanocomposites with and without EVAgAA were prepared by melt mixing in a Haake intermixer with different contents of silica and EVAgAA. Their structure and morphology were characterized by Fourier transform infra-red (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), and the mechanical, rheological, dielectrical, and flammability properties of the nanocomposites were also investigated. The FT-IR spectra of the nanocomposites confirmed the formation of hydrogen bonds between the surface silanol groups of nanosilica and C=O groups of EVA and/or EVAgAA. The presence of EVAgAA remarkably increased the intensity of hydrogen bonding between nanosilica and EVA which not only enhanced the dispersion of nanosilica in EVA matrix but also increased the mechanical, viscosity and storage modulus of EVA/silica nanocomposites. In addition, the flammability of EVA/silica nanocomposites is also significantly reduced after the functionalization with EVAgAA. However, the mechanical properties of EVA/silica nanocomposites tended to level off when its content was above 1.5 wt.%. It has also been found that the dielectric constant value of the EVA/EVAgAA/silica nanocomposites is much lower than that of the EVA/silica nanocomposites, which is another evidence of the hydrogen bonding formation between EVAgAA and nanosilica.