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In this study, the synthesis of porous titania-silica (TiO2-SiO2) composite aerogel at ambient pressure by using non-hazardous chemicals as a source of silica was investigated. TiO2-SiO2 composite aerogels were characterised and their photocatalytic performances were investigated for the removal efficiency of acetaldehyde and NO(x) under UV light. Results showed that porous composite aerogel with aggregated morphology, high surface area and an increased mesoporosity were formed. TiO2-SiO2(1.8) composite, with high Ti/Si ratio, showed the best results in terms of photocatalytic removal of acetaldehyde and nitrogen oxide.

The incorporation of zirconia onto the silica supports of platinum catalysts improved the selective reduction of NO by hydrogen in comparison to platinum catalysts supported on silica and alumina. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, the temperature-programmed desorption of ammonia, X-ray photoelectron spectroscopy, and the adsorption of carbon monoxide. Their performances were examined in a flow microreactor and by in situ IR spectroscopy. The incorporation of zirconia onto silica created many strong acid sites and stabilized the dispersed platinum. It aided the adsorption of NO and enhanced the formation of ammonia on the platinum catalysts, even in the presence of excess oxygen. The formation of ammonia from NO and the subsequent removal of NO through reaction with ammonia considerably improved the conversion of NO and the yield of N2. The presence of zirconia also improved the stability of the supported platinum against hydrothermal treatment.

Four kinds of MFI-meso zeolites with both micro- and mesopores were prepared, characterized, and their catalytic activities were evaluated in the liquid-phase degradation of high-density, low-density, and linear low-density polyethylene (HDPE, LDPE, and LLDPE) in order to discuss their catalytic performance in relation to their porous characteristics and acidity. MFI-syn that was synthesized from partially dissolved MFI zeolite and MFI-sda that was prepared by using a special structure directing agent exhibited highly ordered mesopores with strong acidity and achieved high conversions, about 95%, even with small catalyst loadings (HDPE/catalyst = 20 g/0.05 g) at 380 °C. However, MFI-oxy prepared from an oxyacid-added mixture exhibited a poor catalytic activity because of its low acidity and small pore volume. MFI-alk prepared by an alkali treatment exhibited irregular mesopores and medium conversions. MFI-meso zeolites were especially suitable for the degradation of HDPE and LLDPE, which required a high external surface for the initial degradation of polyethylene and a rapid mass transfer, resulting in a higher catalytic activity. The enhancement of catalytic activity in the degradation of LDPE by the introduction of mesopores was relatively small because of its rapid initial degradation.

Platinum catalysts supported on silicas with various physicochemical properties were prepared in order to investigate the effect of silica characteristics on their platinum dispersion and catalytic activity in the oxidation of carbon monoxide. Although titania-incorporation into silica and further treatment of the impregnated platinum precursor with hydrogen peroxide were effective for improving the dispersion and stability of platinum catalysts supported on silicas, regardless of the characteristic of the silicas, the platinum catalysts supported on fumed silica with a medium level of surface hydroxyl group concentration exhibited the highest catalytic activity among those supported on mesoporous silica, silica gel, and precipitated silica. The required properties of the highly active platinum catalyst seemed to be a high dispersion of platinum, the formation of a stable titania layer, and the generation of strong acid sites. By contrast, the precipitated silica with a small surface area and high concentration of surface hydroxyl groups was not appropriate for a catalytic support for platinum catalysts.

Aim: Thromboxane A synthase (TBXAS1) converts prostaglandin H to thromboxane A, a potent constrictor of smooth respiratory muscle. Thus, functional alterations of the TBXAS1 gene may contribute to aspirin-intolerant asthma (AIA). Materials & methods: We investigated the relationship between SNPs in the TBXAS1 gene and AIA. Asthmatics (n = 470) were categorized into AIA (20% or greater decreases in forced expiratory volume in 1 s [FEV1], or 15% to 19% decreases in FEV1 with naso-ocular or cutaneous reactions) and aspirin-tolerant asthma (ATA). A total of 101 SNPs were genotyped. mRNA expression of the TBXAS1 gene by peripheral blood mononuclear cells and plasma thromboxane B2 (TXB2) concentrations were measured by reverse transcriptase (RT)-PCR and ELISA. Results: Logistic regression analysis showed that the rare allele frequency of rs6962291 in intron 9 was significantly lower in the AIA group (n = 115) than in the ATA group (n = 270) (pcorr = 0.04). The linear regression analysis revealed a strong association of rs6962291 with the aspirin challenge-induced FEV1 fall (p = 0.003). RT-PCR revealed an exon-12-deleted splice variant. We measured TBXAS1 mRNA levels in peripheral blood mononuclear cells. The mRNA levels of the full-length wild-type and splice variant were significantly higher in the TT homozygotes than in the AA homozygotes of rs6962291 (1.00 ± 0.18 vs 0.57 ± 0.03 and 1.00 ± 0.18 vs 0.21 ± 0.05, p = 0.047 and 0.001, respectively). The plasma TXB2 level was significantly lower in rs6962291 AA carriers than in rs6962291 TT (p = 0.016) carriers. Conclusion: The rare allele of rs6962291 may play a protective role against aspirin hypersensitivity via a lower catalytic activity of the TBXAS1 gene, attributed to the increase of a nonfunctioning isoform of TBXAS1. Original submitted 26 August 2010; Revision submitted 29 October 2010.

Nuclear factor-κB (NF-κB) orchestrates the expression of genes responsible for airway inflammation and remodeling in asthma. The activity of NF-κB is tightly regulated by IKBA, which may be modulated by genetic polymorphisms of the IKBA gene. We investigated the association between asthma susceptibility and IKBA gene polymorphisms in a Korean population. Genotyping was performed in BA (bronchial asthma) and NC (normal control). We measured reverse transcription-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay, and luciferase reporter assays, respectively. A -673A>T (rs2233407) was associated with asthma development in subjects with atopic asthma (odds ratio = 0.56, p = 0.004). The IKBA mRNA level was higher in B-cell lines with the rs2233407 TT genotype compared with those with the AA genotype (p = 0.024). The luciferase activity of the rs2233407 T genotype was higher than that of the A (p = 0.002). The cytoplasmic levels of total IKBA and IKBA [p-S32] were higher in B cell lines of the rs2233407 TT genotype than those of the AA (p = 0.016 and p = 0.036, respectively), whereas nuclear NF-κB activity in cells with the IKBA rs2233407 AA genotype was higher than in cells with the AA (p = 0.038). The IKBA rs2233407 A>T polymorphism may predispose individuals to the development of atopic asthma via regulation of IKBA gene expression at the transcriptional level.

Highly active and stable platinum catalysts for propane combustion were prepared by impregnating platinum on zirconia-incorporated silica by combining the high surface area of silica with the exceptional thermal stability of zirconia. The thermal stability of the platinum catalysts was examined after thermal aging at 800 °C for 50 h. The physico-chemical states of the platinum and zirconia were investigated by using various analytical instruments, CO and H2 chemisorption, and temperature-programmed-desorption of ammonia. The platinum catalysts prepared on the zirconia-incorporated silica and treated with hydrogen peroxide showed high catalytic activity and stability in propane combustion. The high dispersion of platinum and the acid site generation achieved due to the incorporation of zirconia on the silica were responsible for the high activity and stability of the catalysts. Highly active and stable platinum catalysts for propane combustion were prepared by impregnating platinum on zirconia-incorporated silica by combining the high surface area of silica with the exceptional thermal stability of zirconia. The platinum catalysts supported on zirconia-incorporated silica maintained their activity after thermal aging at 800 °C for 50 h.]

Transesterification of triacetin, tributyrin and soybean oil with methanol was examined over rehydrated hydrotalcites (HT-reh), which were previously calcined at 550 °C and exposed to an ambient atmosphere, in order to investigate the effect of the water content on their catalytic activity. Rehydration of a calcined hydrotalcite at 25 °C produced uniform mesopores of around 4 nm diameter, while the removal of water from the HT-reh by pretreatment at 500 °C, formed large heterogeneous mesopores. Methanol was adsorbed and desorbed rapidly in the mesopores of the HT-reh filled with water. The pretreatment of the HT-reh at 500 °C removed both water and carbon dioxide, producing strong basic sites. The high activity of fully rehydrated hydrotalcite in the transesterification of three triglycerides was explained by the generation of Bronsted basic sites and the rapid migration of methanol in the mesopores, while the improved activity of the rehydrated hydrotalcite pretreated at 500 °C by the generation of strong basic sites and empty mesopores due to the removal of water and carbon dioxide.

Four kinds of large port zeolites BEA, FAU, LTL and MOR, were used as catalysts in the dehydration of a large molecule, epiandrosterone, to elucidate the effect of their pore structure on its conversion and the selectivity for 5α-androst-2-en-17-one (Δ2-olefin). Silane masking of the zeolite acid sites, measurement of their epiandrosterone uptake, and theoretical calculations to find the energy-minimized conformation in zeolite pores revealed the roles of pore structure and acid sites in the dehydration. LTL and MOR zeolites showed poor conversion and low selectivity for Δ2-olefin because of the close packing in their linear pores. BEA and FAU zeolites with three-dimensionally connected pores exhibited high conversion. Since the supercages of FAU zeolite provided enough space to allow tilted conformation of epiandrosterone with high preference for the formation of Δ2-olefin, FAU zeolites with a sufficient number of acid sites demonstrated both high conversion and selectivity in the dehydration of epiandrosterone.

The deactivation of a barium oxide-based NOx storage and reduction (NSR) catalyst with hydrothermal treatment was studied by treating it with 10 vol% water vapor diluted in nitrogen at 850°C. XRD, XPS, SEM, IR of CO adsorption, and the N2 adsorption was used to investigate the physical and chemical changes of the NSR catalyst caused by the hydrothermal treatment. The 12 h hydrothermal treatment decreased its NO2 storage capacity by 20%. However, the hydrothermal treatment significantly decreased its ability to reduce the stored NO2. The formation of an inactive phase consisting of platinum and aluminum is believed to be the cause of the severe deactivation of the NSR catalyst.

Barium oxide-based NO x storage and reduction (NSR) catalysts with different amounts of potassium oxide were prepared to investigate the role of potassium oxide in the aspects of amount and strength of NO 2 storage. The dispersion of barium and potassium oxides on alumina, the amount and state of NO 2 stored on them, and the desorption profiles of NO 2 from them were examined by XRD, N 2 adsorption, electrical conductivity measurement, XPS, FT-IR and TPD techniques. Barium and potassium oxides were mainly loaded in the mesopores of the alumina and the NO 2 was stored by being converted to nitrates. The alumina itself had a small capacity for NO 2 storage, but the impregnation with potassium oxide increased the capacity. The co-loading of potassium oxide and barium oxide enhances the strength of the interaction between the storage material and NO 2 , shifting the desorption peak of NO 2 to a elevated temperature.

In the past few years, silica-modified titania has drawn increasing attention due to their special properties making them ideal candidates for a wide range of applications. In this study, we report a novel method for the synthesis of silica-modified titania by a sol-gel method using sodium silicate solution (1 M). The hydrolysis and condensation reactions of titanium dioxide (TiO2, Degussa Aeroxide® P25) in sodium silicate solution proceeded with citric acid (3 M) as a catalyst. The orbital shaking method was followed for the removal of sodium salt formed during the sol-gel process. Solvent exchange was carried out using methanol and hexane. Finally, chemical modification of the gel was conducted using trimethylchlorosilane followed by ambient pressure drying. The obtained silica-modified titania was characterised for nanostructural analysis using scanning electron microscopy and transmission electron microscopy. The nitrogen adsorption-desorption measurements were employed to investigate the BET surface area, pore structure and pore volume of specimens. Thermal gravimetric analysis showed exothermic peaks at temperature range of 90-190 °C representing the oxidation of organic groups from--Si-R network. The silica-modified titania showed high photocatalytic activity and an easy recovery using crystal violet as model water pollutant.

In this study, titania photocatalyst was produced from the wastewater sludge of Ti-salt flocculation. The high photocatalytic activity of titania reported was evaluated based on a single organic substrate. However, the photocatalytic activity is a substrate-specific; one photocatalyst showed different photocatalytic degradation rates for different substrates. Thus, to investigate the substrate-specific photocatalytic activity of titania, various substrates of humic acid (HA), dichloroacetic acid (DCA), rhodamine B (RhB), metsulfuron methyl (M&M) and phenol were used under simulated solar light irradiation. Results showed titania had a high activity rate for RhB, moderate activity for HA and DCA and low activity for M&M and phenol indicating substrate-specific activities. When compared with Degussa-P25, titania showed higher activity for M&M, while the opposite was observed for HA and phenol. The specific-substrate behaviour of titania could depend on specific physicochemical and electronic interactions between titania, substrates, and their intermediates compounds formed.

The adsorption of pyridine onto the metal organic framework MIL-101 was investigated by experimental and theoretical methods. The amount of pyridine adsorbed on MIL-101 was extraordinarily large at 20 °C, corresponding to about 950 mg/g of dried MIL-101 and approximately half of the voids being filled. Most of the pyridine that had filled the voids was rapidly removed by evacuation at room temperature, but some of the pyridine was so strongly adsorbed that it was retained even under evacuation at 150 °C. Although IR spectra of the adsorbed pyridine indicated the adsorption of pyridine as pyridinium ions and coordinated pyridine at low temperatures, increasing the adsorption temperature induced partial cleavage of the pyridine rings. The high stabilization energy of pyridine on the coordinative unsaturated sites (CUS) of MIL-101, obtained by theoretical calculation, -103 kJ/mol, supported the strong adsorption of pyridine on the CUS.

Acetyl salicylic acid (ASA; aspirin)-intolerant asthma (AIA) is a distinct clinical condition characterized by the 'aspirin triad' syndrome of aspirin hypersensitivity, eosinophilic rhinosinusi-tis, nasal polyposis, and bronchial asthma, and is known to af-fect 10-20% of adult asthmatic patients (1-7). AIA is due to the development of bronchoconstriction in asthma patients follow-ing ingestion of aspirin or other non-steroidal anti-inflamma-tory drugs (NSAIDs). Although the underlying mechanisms of AIA have not been elucidated completely, arachidonic acid metabolites such as prostaglandins (PGs), leukotrienes (LTs), and thromboxane (TBX) are reportedly involved in the patho-genesis of this asthma phenotype (8-10). Anti-inflammatory PGs are one of the various types of oxygenated metabolites generated by the cyclooxygenase (COX) pathway that function to reduce the level of PGE2, the main COX2 metabolite (11-13). The cyclooxygenase theory is widely accepted as re-sponsible for the pathogenesis of AIA. Inhibition of COXs by NSAIDs in the respiratory tract alters arachidonic acid metabo-lism, leading to reduction of PGE2 and alteration of AIA patho-genesis (9-11, 14, 15). Therefore, the overproduction or under-production of critical mediators of arachidonic acid metabo-lism, such as PGs, probably accounts for disease susceptibility (2).Prostaglandin E2 (PGE2), an arachidonic acid metabolite, is a key factor in the generation of abnormal pain sensations in-cited by inflammation (16). PGE2 is synthesized and secreted by diverse cell types and plays an important role in balancing the Th1/Th2 immune responses (17, 18). PGE2 exerts its bio-logical effects by binding to four different G protein-coupled receptors encoded by the following separate genes

BackgroundWe previously demonstrated that single nucleotide polymorphism (SNP) and haplotypes were associated with aspirin hypersensitivity in asthmatics. We investigated the genetic effects of the SNPs and haplotypes on the expression of theCysLTR2gene.MethodsWe measured CysLTR2 protein and mRNA expression in EB virus-infected B cell lines from asthmatics havinght1+/+andht2+/+. A gel retardation assay was used to identify nuclear protein binding to the c.-819 promoter site. The function of promoter and 3'-UTR were assessed using pGL3 luciferase and pEGFP reporter system, respectively.ResultsWe found that the expression of CysLTR2 protein was higher in B cell lines of asthmatics havinght2+/+than in those havinght1+/+. PMA/ionomycin induced higher mRNA expression of CysLTR2 in B cell lines fromht2+/+asthmatics than those fromht1+/+asthmatics. A nuclear protein from the B cell lines showed stronger DNA binding affinity with a probe containingc.-819T thanone containingc.-819G. The luciferase activity of thec.-819Ttype ofCysLTR2promoter was higher than that of thec.-819Gtype. EGFP expression was higher in the EGFP-c.2078T3'-UTR fusion construct than in thec.2078Cconstruct.ConclusionThe sequence variants ofCysLTR2may affect its transcription and the stability of its mRNA, resulting in altered expression of CysLTR2 protein, which in turn causes some asthmatics to be susceptible to aspirin hypersensitivity.

Sulfonic acid-incorporated-MCM-41 mesoporous materials prepared using a silane containing tetrasulfide linkages showed exceptional yields of the acetylated product in the acetylation of anisole due to their high content of strong acid sites.