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[Display omitted] • New support for immobilization PTA was developed from polycationic grafted on silica nanoparticles (SNSs- g -PMVP). • PTA on SNSs- g -PMVP was finely dispersed with the size of 1–2 nm. • SNSs- g -PMVP/PTA can increase the solketal yield to above 90% within 1 h of the ketalization. Solketal, a fuel additive, was synthesized from the solvent-free ketalization reaction of glycerol and acetone using phosphotungstic acid (PTA) catalysts. Due to strong acidity, PTA is expected to serve as an efficient acid catalyst, however low specific surface area of bulk PTA and the deactivation, by water, denounces its acid activity leading to low solketal production. The present study demonstrates a success in increasing the solketal yield in the ketalization catalyzed by PTA immobilized in the layer of poly(N -methyl-4-vinylpyridinium) grafted on silica nanoparticles (SNSs- g -PMVP/PTA). PTA with the size of 1–2 nm were dispersed in the grafted-layer of PMVP under strong binding to positively charged pyridinium while the grafted-PMVP provided the hydrophobic environment improving the water-tolerance of PTA. In addition, acid-base interactions between PTA and the pyridine group in the grafted-PMVP transformed PTA hexahydrate to PTA trihydrate. Using SNSs- g -PMVP/PTA catalyst resulted in increasing of the solketal yield above 90% within an hour of the glycerol ketalization compared with 17% yield of solketal in the ketalization catalyzed by unsupported PTA. [ABSTRACT FROM AUTHOR]

The objectives of this study were to develop and measure the hydrodynamic particle size of sildenafil citrate nanoparticles dispersed in a pressurized metered-dose inhaler (pMDI) using dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). Aerodynamic properties and charges of aerosolized particles after emission from the pMDI were monitored by next generation impactor (NGI) and electrical low pressure impactor (ELPI). Nanodispersion-based sildenafil citrate pMDI formulated with 0, 1, 5 and 10% poloxamer 188 (P188) as a surfactant namely formulations F1, F2, F3 and F4, respectively. The results showed no precipitated or crystal growth during 6 months. The particle size and polydispersity index of the F3 obtained from the DLS analysis were 9.0 ± 1.6 d nm and 0.421 ± 0.038, respectively. The respective characteristics obtained from the SAXS data were 5.2 ± 1.2 d nm. The results from SAXS were smaller than those obtained from DLS. Larger hydrodynamic shell contributed to the larger size of nanoparticles. The sildenafil citrate content of pMDI was 107–109.5% LA. The mass median aerodynamic diameter (MMAD) from NGI was 1.2–2 μm and the fine particle fraction was 60%. The formulation without P188 (F1) showed particles of 10–100 nm and 0.1–1 μm and exhibited a unipolar charge profile. The formulations with P188 exhibited a bipolar charge profile with the nano-size of 200 (F3) and 300–800 nm (F4). The formulations of pMDI exhibited either a unipolar charge or bipolar charge profile depending on the composition of the formulation. The sildenafil citrate pMDI with 5% P188 generated sub-micronized and nano-sized aerosols with bipolar charged particles. The DLS and SAXS techniques were alternative ways to determine the particle size and size distribution of the pMDI products. The EPLI is also suitable to assess the stability of the MDI products from charge measurement.

Surface-modified hexagonal zinc oxide (ZnO) prisms were incorporated into commercial polyurethane (PU) coating. Dip-coated PU/ZnO composite films on polypropylene sheets exhibited a broad dip in ultraviolet (UV) transmittance corresponding to the ZnO band gap. Compared to 5 and 10 wt% loading, optical properties of PU composites were significantly modified by 20 wt% ZnO fillers in terms of the blue shift and splitting of UV peaks with substantially increased absorption. The morphology effect is demonstrated by replacing the hexagonal ZnO with sword-like ZnO. The sword-like ZnO gave rise to a lower UV absorption and the two slope characteristic in small angle X-ray scattering spectrum corresponding to the thin parts at tapered ends. The proposed procedure and materials used in this work are appropriate for economic large-scale production of composites.

The evaluation of PEG as a gelation solvent for an organogel based on β-cyclodextrin (β-CyD) was investigated using principal component analysis (PCA). The test tube tilting method was performed to examine the gel formation experimentally. The important descriptors used in the PCA included the Hansen partial solubility parameters. LogP may be able to be used as an additional descriptor for this system. According to PCA analysis, PEG was in a cluster of gelation solvents. Subsequently, various PEG liquid state grades were tested for their ability to gel the system and PEG400 was found to be able to produce a gel. This verifies that PCA can be successfully used to evaluate the role of PEG. Accordingly, this PCA method may be an effective tool to evaluate the role of any solvent for other low molecular weight gelators (LMWGs). Afterwards, the optimal components in the system were explored, and it was found to be 0.1M β-CyD, 0.5M K2CO3 in PEG400. Based on WAXS, the gel fiber of this organogel was demonstrated to be amorphous. This forming organogel will be further characterized in details and investigated for use in a drug delivery system.

Magnetic fluid is a special class of materials which possesses the advantages of a liquid state of the carrier and a magnetic state of the particles. In addition to the conventional uses in mechanical engineering, magnetic fluids containing magnetite (Fe3O4) superparamagnetic nanoparticles are under research and development for drug delivery, hyperthermia and MRI contrast agents. On the other hand, iron-platinum (FePt) is investigated as materials for ultrahigh density recording. Before their assembly into patterned media, the as-synthesized FePt nanoparticles in superparamagnetic state are commonly stored in forms of magnetic fluids. In this work, iron-platinum (FePt) nanoparticles with their surface modified by oleic acid and oleyleamine were synthesized from the polyol process. The starting material was an environmental friendly iron(III) acetylacetonate and the products were dispersed in n-hexane. In small-angle X-ray scattering (SAXS) measurements at the Synchrotron Light Research Institute, Thailand, each magnetic fluid was injected into a sample cell with aluminum foil windows and the X-ray of wavelength 1.55 Å from BL2.2 was used. The measured SAXS intensity profiles as a function of the scattering vector from 0.27 to 2.30 nm-1 were fitted and compared between two different reactions. Nanoparticles synthesized by using a higher amount of Fe(acac)3 were matched with monodisperse spheres of radius 2.4±0.3 nm. The other reaction with a reducing agent gave rise to smaller nanoparticles of two size distributions. From this work, the potential of synchrotron radiation to complement conventional characterization techniques in the investigation of nanoparticles for high density recording and biomedical applications is underlined.

The 0.98BaTiO3-0.02Ba (Mg1/3Nb2/3) O3 ceramics has been synthesized through a conventional mixed-oxide by using BT nanopowder and BMN micropowder. The phase purity of the powders and the ceramics was examined using X-ray diffraction (XRD). The 0.98BT-0.02BMN powders were sintered to 92% of the theoretical density at a temperature of 1300 °C for 2 h. The microstructure of the sintered surface was investigated using scanning electron microscopy (SEM). The dielectric constant (εr) and loss factor (tanδ) of the sintered pellets at Curie temperture were 3000 and 0.015, respectively.