Probing local structure of glass with orientation-dependent luminescence.

The local ordering of particles is considered an important process in glass transition. Ordering is usually observed in simulation and micrometer-sized colloid. However, clear information on local ordering at the molecular level is difficult to obtain experimentally. In this study, we prepared an easily glass-forming fluorophore with a color change owing to the intermolecular arrangement in the liquid, glass, and crystal states. The bathochromic shifts of the photoluminescence spectra indicated a change in the intermolecular orientation upon immediate cooling of the melt. The recovery of the spectra by successive heating indicated that rotation contributed to the change in the intermolecular orientation. The orientation in the glass was distinct from that during crystal growth, which was observed as a slow bathochromic shift by maintaining the temperature between the melting points of the blue- and green-luminescent crystals obtained from dichloromethane/ethanol and dichloromethane/hexane, respectively. Our results demonstrate that the anisotropic interaction between glass-forming luminophores is useful for uncovering molecular-level events in the glassy state.

Epidermal growth factor receptor/heme oxygenase-1 axis is involved in chemoresistance to cisplatin and pirarubicin in HepG2 cell lines and hepatoblastoma specimens.

PURPOSE: To investigate the possibility that the antioxidant stress protein Heme oxygenase-1 (HO-1) is involved in the acquisition of chemoresistance in cisplatin and pirarubicin (CITA) therapy. METHODS: Human hepatoblastoma-derived cell line (HepG2) was used to generate a knockdown cell line of HO-1 by small interfering RNA (siRNA). Expression of HO-1, epidermal growth factor receptor (EGFR), Akt, and extracellular signal-regulated kinase1/2 (ERK1/2) was examined by Western blot. The cytotoxic effect of cisplatin, pirarubicin, and EGFR inhibitor was examined by trypan blue staining. In human hepatoblastoma specimens (n = 5), changes of HO-1 expression were examined immunohistochemically before and after CITA therapy. RESULTS: HO-1 expression in HepG2 cells was increased by the treatment of cisplatin (CDDP) and pirarubicin (THP) dose-dependently. In HO-1 knockdown HepG2 cells, the HO-1 was not expressed and the percentage of trypan blue-positive cells (dead cells) was significantly increased after treatment of CDDP and THP. The EGFR inhibitor decreased the levels of HO-1, phospho-Akt and phospho-ERK1/2 in HepG2 cells. Combination treatment of EGFR inhibitor with CDDP and THP increased the cytotoxic effect in HepG2 cells. In human hepatoblastoma specimens, 4 of the 5 patients (80%) showed HO-1 expression changed much stronger in the viable tumor cells after CITA therapy. CONCLUSION: The cytotoxic effects of CDDP and THP were both enhanced under HO-1 knockdown conditions as well as under conditions that inhibit the activation pathway of HO-1 by EGFR inhibitors. EGFR/HO-1 axis may be involved in acquiring chemoresistance in HepG2 cell lines as well as in human hepatoblastoma.

Intra- and intermolecular interaction of anthracene moieties in 7,8-disilabicyclo[3.3.0]octadienyl-bridged bisanthracenes.

Ruthenium-catalyzed dimerization of 9-anthrylarylsilanes afforded air-stable V-shaped bisanthracenes bridged by a 7,8-disilabicyclo[3.3.0]octadiene moiety. The intra- and intermolecular proximity of the anthracene moieties were determined by single-crystal X-ray analysis. Absorption and emission maxima of the disilabicyclo[3.3.0]octadienyl-bridged bisanthracenes in the solution state were observed at longer wavelengths than those of 9-anthryldimethylsilane and bis(9-anthryl)dimethylsilane. The V-shaped bisacenes in the solid state showed excimer emissions with moderate quantum yields.

Photocurable ABA triblock copolymer-based ion gels utilizing photodimerization of coumarin.

Herein, we develop a photocurable ABA triblock copolymer-based ion gel, which can be converted from a thermally processable, physically crosslinked ion gel to a thermally and mechanically stable, chemically crosslinked ion gel via photoinduced dimerization. The A block consists of a random copolymer of N-isopropylacrylamide and a coumarin-containing acrylate monomer, while the B block consists of an ionic liquid-philic poly(ethylene oxide). Due to the upper critical solution temperature-type phase behavior of the A block, the ABA triblock copolymer undergoes gel-to-sol transitions in a hydrophobic ionic liquid as the temperature is increased. Furthermore, under ultraviolet (UV) light irradiation, the physical crosslinks formed by association of the A blocks in the gel at low temperatures become chemically crosslinked as a result of photodimerization of the coumarin moieties in the A block; this results in conversion from a thermo-reversible, physically crosslinked ion gel to a thermo-irreversible, chemically crosslinked ion gel. The rheological changes of the ion gel upon UV irradiation have been investigated in detail. In addition, photopatterning of the ion gel has been realized by exploiting the photocurable behavior of the ABA triblock copolymer in the ionic liquid.

Enhanced Ga2O3-photocatalyzed and photochemical degradation of the Fipronil insecticide by UVC irradiation in mixed aqueous/organic media under an inert atmosphere.

Agrochemicals such as the insecticide Fipronil that bear fluoro groups are generally fat-soluble and nearly insoluble in water, so that their photodegradation in a heterogeneous aqueous gallium oxide dispersion presents some challenges. This article examined the photodegradation of this insecticide by solubilizing it through the addition of organic solvents (EtOH, MeOH, THF, 1,4-dioxane and ethylene glycol) to an aqueous medium and then subjecting the insecticide to 254 nm UVC radiation under photocatalytically inert (Ga2O3/N2) and air-equilibrated (Ga2O3/O2) conditions, as well as photochemically in the absence of Ga2O3 but also under inert and air-equilibrated conditions. Defluorination, dechlorination, desulfonation and denitridation of Fipronil were examined in mixed aqueous/organic media (10, 25 and 50 vol% in organic solvent). After 3 h of UVC irradiation (50 vol% mixed media) defluorination with Ga2O3/N2 was ∼65% greater than in aqueous media, and ca. 80% greater than the direct photolysis of Fipronil under inert (N2) conditions; under air-equilibrated conditions both Ga2O3-photocatalyzed and photochemical defluorination were significantly lower than in aqueous media. Dechlorination of Fipronil was ∼160% (Ga2O3/N2) and 140% (photochemically, N2) greater than in aqueous media; under air-equilibrated conditions, both photocatalyzed and photochemical formation of Cl(-) ions in mixed media fell rather short relative to aqueous media. The photocatalyzed (Ga2O3/N2) and photochemical (N2) conversion of the sulfur group in Fipronil to SO4(2(-)) ions was ca. 20% and 30% greater, respectively, in mixed media, while under air-equilibrated conditions photocatalyzed desulfonation was nearly twofold less than in the aqueous phase; direct photolysis showed little variations in mixed media. Denitridation of the nitrogens in Fipronil occurred mostly through the formation of ammonia (as NH4(+)) under all conditions with negligible quantities of NO3(-); again mixed media offered enhanced denitridation, particularly under inert N2 conditions. Time-of-flight electrospray (TOF-MS/ESI(-)) mass spectrometry revealed a fairly large number of intermediates formed in the degradation of Fipronil, particularly under photocatalytic conditions. Only a couple of intermediates were identified in the photodegradation and the presence of Ga2O3 enhanced the complexity of an already cumbersome problem owing to the involvement of organic solvents.

Photoassisted defluorination of fluorinated substrates and pharmaceuticals by a wide bandgap metal oxide in aqueous media.

Persistent fluorinated substances, such as the fluorine-bearing pharmaceutical drugs Fluoxetine (FLX; Prozac) and Fluvoxamine maleate (FOM) together with several other substrates (fluorobenzoic acid and fluoroaliphatic model compounds), were photochemically defluorinated and degraded under UVC illumination in relatively good yields in the presence of a wide band gap metal oxide (ß-Ga2O3) in heterogeneous aqueous media. The formation of fluoride ions increased with increasing illumination time under an inert nitrogen atmosphere, the transformation of the aromatic moiety was slower under these conditions, but nonetheless it did occur. The optimal amount of ß-Ga2O3 loading for defluorination was 50 mg in aqueous media (0.10 mM, 100 mL); the optimal pH to defluorinate FLX was pH 6. Platinization (1 wt%) of the gallium oxide particles enhanced defluorination under an inert nitrogen atmosphere, but was decreased under an oxygen atmosphere; however, in the latter case the degradation of the substrates was facilitated as witnessed by loss of the aromatic moiety. The Ames test on the intermediate products from the photodegradation of FLX and 4-(trifluoromethyl)benzoic acid after long illumination times revealed that none were mutagenic.

Photooxidation of the antidepressant drug Fluoxetine (Prozac®) in aqueous media by hybrid catalytic/ozonation processes.

This article examines the oxidative disposal of Prozac(®) (also known as Fluoxetine, FXT) through several oxidative processes with and without UV irradiation: for example, TiO(2) alone, O(3) alone, and the hybrid methods comprised of O(3) + H(2)O(2) (PEROXONE process), TiO(2) + O(3) and TiO(2) + O(3) + H(2)O(2) at the laboratory scale. Results show a strong pH dependence of the adsorption of FXT on TiO(2) and the crucial role of adsorption in the whole degradation process. Photolysis of FXT is remarkable only under alkaline pH. The heterogeneous photoassisted process removes 0.11 mM FXT (initial concentration) within ca. 60 min with a concomitant 50% mineralization at pH 11 (TiO(2) loading, 0.050 g L(-1)). The presence of H(2)O(2) enhances the mineralization further to >70%. UV/ozonation leads to the elimination of FXT to a greater extent than does UV/TiO(2): i.e., 100% elimination of FXT is achieved by UV/O(3) in the first 10 min of reaction and almost 97% mineralization is attained under UV irradiation in the presence of H(2)O(2). The hybrid configuration UV + TiO(2) + O(3) + H(2)O(2) enhances removal of dissolved organic carbon (DOC) in ca. 30 min leaving, however, an important inorganic carbon (IC) content. In all cases, the presence of H(2)O(2) improves the elimination of DOC, but not without a detrimental effect on the biodegradability of FXT owing to the low organic carbon content in the final treated effluent, together with significant levels of inorganic byproducts remaining. The photoassisted TiO(2)/O(3) hybrid method may prove to be an efficient combination to enhance wastewater treatment of recalcitrant drug pollutants in aquatic environments.

Sunlight photo-assisted TiO2-based pilot plant scale remediation of (simulated) contaminated aquatic sites.

A tubular-type solar photoreactor system powered by commercial solar panels and consisting of six 20-tube modules (Pyrex glass) to mimic a pilot plant scale configuration was designed and constructed to examine the remediation of simulated wastewaters contaminated with various classes of organic pollutants such as endocrine disruptors (e.g. bisphenol A), anionic surfactants (sodium butylnaphthalenesulfonate and sodium dodecyl- benzenesulfonate), herbicides (e.g. 2,4-dichlorophenoxyacetic acid) and a commercial dishwasher detergent. Photo-oxidative processes followed first-order kinetics expressed in terms of the total light energy (in kJ) that impinged on the photoreactor. The influence of TiO2 loading and circulation flow rate of the wastewaters on the dynamics of the photo-oxidation to mineralization (loss of total organic carbon, TOC, or formation of sulfate ions) was investigated. The optimal operational parameters were: TiO2 loading, 2 g L⁻¹; circulation flow rate, 7.5 L min⁻¹. On a sunny day, near- quantitative mineralization of the contaminants was achieved after only 4 h of irradiation that corresponded to an accumulated energy of ca 1380 kJ.

Polystyrenes with chiral phosphoramide substituents as Lewis base catalysts for asymmetric addition of allyltrichlorosilane: enhancement of catalytic performance by polymer effect.

In the asymmetric addition of allyltrichlorosilane to benzaldehyde, polystyrenes with chiral phosphoramide substituents as Lewis base catalysts showed up to 2.4 times better catalytic activity and 1.4 times higher enantioselectivity than the corresponding low-molecular-weight analogues.