Soluble iron modulates iron oxide particle-induced inflammatory responses via prostaglandin E2 synthesis: In vitro and in vivo studies

Background  

Ambient particulate matter (PM)-associated metals have been shown to play an important role in cardiopulmonary health outcomes. To study the modulation of PM-induced inflammation by leached off metals, we investigated intracellular solubility of radio-labeled iron oxide (⁵⁹Fe₂O₃) particles of 0.5 and 1.5 μm geometric mean diameter. Fe₂O₃ particles were examined for the induction of the release of interleukin 6 (IL-6) as pro-inflammatory and prostaglandin E₂ (PGE₂) as anti-inflammatory markers in cultured alveolar macrophages (AM) from Wistar Kyoto (WKY) rats. In addition, we exposed male WKY rats to monodispersed Fe₂O₃ particles by intratracheal instillation (1.3 or 4.0 mg/kg body weight) to examine in vivo inflammation.     

Synergistic effect of co-exposure to carbon black and Fe2O3 nanoparticles on oxidative stress in cultured lung epithelial cells

Background  

There is a need to better understand synergism in the biological effects of particles composed of multiple substances. The objective of this study was to determine if the oxidative stress in cultured cells caused by co-exposure to carbon black and Fe₂O₃ nanoparticles was significantly greater than the additive effects of exposure to either type of particles alone; and to determine a possible cause for such synergistic effect if one was found. Cultured A549 human lung epithelial cells were exposed to (1) carbon black nanoparticles alone, (2) Fe₂O₃ nanoparticles alone, and (3) both types of particles simultaneously. Protein oxidation, lipid peroxidation, and cellular uptake of Fe in these cells were measured after 25 hours of exposure. The reduction of solubilized Fe³⁺ by the carbon black nanoparticles was measured separately in a cell-free assay, by incubating the carbon black and the Fe₂O₃ nanoparticles in 0.75 M sulfuric acid at 40°C and measuring the amount of reduced Fe³⁺ at different time points up to 24 hours.     

An Efficient Process for the Cyclization of N-β-hydroxyethyl-N-methyl-1,3-propanediamine to N-methylhomopiperazine Over Cu<Subscript>20</Subscript>Cr<Subscript>10</Subscript>Mg<Subscript>10</Subscript>/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

Abstract  

Continuous synthesis of N-methylhomopiperazine over Cu–Cr–Mg/γ-Al₂O₃ has been developed. The doped Cr improves the dispersion of the Cu⁰ particles and inhibits the generation of CuAl₂O₄ so that the Cu⁰ particles are retained as the active sites. Doped Mg neutralizes the strong acid sites in Cu₂₀Cr₁₀Mg₁₀/γ-Al₂O₃, and led to a decrease in coking side reactions. The reaction parameters were optimized and N-methylhomopiperazine was obtained in a yield of 66%.     

Oxygen Isotope (<Superscript>18</Superscript>O<Subscript>2</Subscript>) Evidence on the Role of Oxygen in the Plasma-Driven Catalysis of VOC Oxidation

Abstract  

This paper reports isotopic evidence on nonthermal plasma-induced fixation of gas-phase oxygen on the surface of several catalysts such as TiO₂, Ag/TiO₂, Ag/γ-Al₂O₃ and Ag/MS-13X at atmospheric-pressure. On-line mass spectrometric analysis and stoichiometric comparison of reactants and products revealed that the fixed surface oxygen can be activated by nonthermal plasma. The fixed ¹⁸O by nonthermal plasma survived for a certain period of time (about 30 min), and involved in the formation of isotope-exchanged oxygen (¹⁸O¹⁶O) and isotope containing CO _x (CO and CO₂).     

Ytterbium Triflate Promoted One-Pot Three Component Synthesis of 3,4,5-Trisubstituted-3,6-dihydro-2<Emphasis Type="Italic">H</Emphasis>-1,3-oxazines

Abstract  

An efficient one-pot synthesis of 3,4,5-trisubstituted-3,6-dihydro-2H-1,3-oxazines from acetylene dicarboxylates, aromatic and aliphatic amines, and formaldehyde is described. The six member N,O-heterocyclic nucleus was constructed via Yb(OTf)₃ promoted domino hydroamination/Prins reaction/cyclization/dehydration reactions.     

Upgrading of Lignin-Derived Compounds: Reactions of Eugenol Catalyzed by HY Zeolite and by Pt/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

Abstract  

The conversion of eugenol (4-allyl-2-methoxyphenol), a compound derived from the lignin in woody biomass, was catalyzed by HY zeolite at 573 K and atmospheric pressure. The main products were isoeugenol and guaiacol, formed by isomerization and by deallylation, respectively. Substituted guaiacols with saturated side-chains (4-methylguaiacol, 4-ethylguaiacol, and 4-propylguaiacol) were also formed, by hydrogen transfer and alkylation reactions. The pseudo-first-order rate constant for the overall disappearance of eugenol was found to be 12.4 L (g of catalyst)/h. When the catalyst was Pt/γ-Al₂O₃ used in the presence of H₂, significant hydrogenation of the propenyl side-chain took place, accompanied by isomerization, and hydrodeoxygenation. Under similar operating conditions, the reaction catalyzed by Pt/γ-Al₂O₃ in the presence of H₂ gave a higher eugenol conversion (X = 0.70) than the reaction catalyzed by HY zeolite (X = 0.11), primarily because of the dominant hydrogenation observed with the former catalyst. In the absence of H₂ as a co-reactant, the acidic γ-Al₂O₃ support in Pt/γ-Al₂O₃ evidently catalyzed all the classes of reactions catalyzed by HY zeolite.     

Direct Synthesis of Dimethyl Carbonate from Methanol and Carbon Dioxide over Ga<Subscript>2</Subscript>O<Subscript>3</Subscript>/Ce<Subscript>0.6</Subscript>Zr<Subscript>0.4</Subscript>O<Subscript>2</Subscript> Catalysts: Effect of Acidity and Basicity of the Catalysts

Abstract  

Ce _X Zr_1−X O₂ catalysts with different cerium content (X) (X = 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1.0) were prepared by a sol–gel method for use in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Among these catalysts, Ce_0.6Zr_0.4O₂ was found to show the best catalytic performance. In order to enhance the acidity and basicity of Ce_0.6Zr_0.4O₂ catalyst, Ga₂O₃ was supported on Ce_0.6Zr_0.4O₂ (XGa₂O₃/Ce_0.6Zr_0.4O₂ (X = 1, 5, 10, and 15)) by an incipient wetness impregnation method with a variation of Ga₂O₃ content (X, wt%). Effect of acidity and basicity of Ga₂O₃/Ce_0.6Zr_0.4O₂ on the catalytic performance in the direct synthesis of dimethyl carbonate was investigated using NH₃-TPD and CO₂-TPD experiments. Experimental results revealed that both acidity and basicity of the catalysts played a key role in determining the catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Large acidity and basicity of the catalyst facilitated the formation of dimethyl carbonate. The amount of dimethyl carbonate produced over XGa₂O₃/Ce_0.6Zr_0.4O₂ catalysts increased with increasing both acidity and basicity of the catalysts. Among the catalysts tested, 5Ga₂O₃/Ce_0.6Zr_0.4O₂, which retained the largest acidity and basicity, showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide.     

Electron micrographic examination of electrodeposited dispersion-hardened nickel

Dispersion-hardened nickel has been produced by electrodepositing Ni from a Watts' bath containing Al₂O₃, TiO₂ and ZrO₂ particles (0.005–0.06m) in suspension. The effect of these particles on the onset of recrystallization at elevated temperatures (up to 1400°C) has been studied and it has been shown that Al₂O₃ is the most effective in stabilizing the electrodeposited structure. Thin films of Ni-Al₂O₃ examined by transmission electron microscopy showed a high dislocation density and restricted twinning, the Al₂O₃ particles being present both within the grains and at the grain boundaries.For optimum thermal stability the oxide should be present in the nickel matrix as discrete particles, but electron microscopy has shown that in all cases agglomeration occurs and that the particles are present as large clusters. Attempts to avoid this difficulty have proved unsuccessful.     

Perovskite-Based Lean-Burn NOx Trap Catalysts Without Using Platinum Group Metals: K/LaCoO3/Ce1?xZrxO2

Abstract  

A series of Ce_1−x Zr _x O₂ (x = 0, 0.1, 0.2, 0.3) solid solution supported lean-burn NO _x trap (LNT) catalysts K/LaCoO₃/Ce_1−x Zr _x O₂ were prepared by successive impregnation. After sulfation the supported perovsikte LaCoO₃ was well maintained; reducing treatment partly destroyed the perovsikte, but it can be well recovered by re-oxidation treatment. Based on NO _x storage and sulfur-resisting performance of the catalysts, the optimal atomic ratio of Zr in Ce_1−x Zr _x O₂ support is x = 0.2. The catalyst K/LaCoO₃/Ce_0.8Zr_0.2O₂ exhibits much better NO _x storage capacity than the Pt-based catalyst Pt/K/Ce_0.8Zr_0.2O₂, which is highly related to its stronger capability for NO to NO₂ oxidation. During NO _x storage much larger amounts of nitrate and nitrite species were identified by in situ DRIFTS over perovskite-based catalysts than over Pt-based one. The H₂-TPR results reveal that after deep sulfation little sulfur species were deposited on the catalyst K/LaCoO₃/Ce_1−x Zr _x O₂, showing strong sulfur-resisting ability. As a result, it is thought that the full replacement of Pt by perovskite LaCoO₃ in the corresponding LNT catalysts is feasible.     

Reductive Amination of Triacetoneamine with <Emphasis Type="Italic">n</Emphasis>-Butylamine Over Cu–Cr–La/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

Abstract  

A series of Cu-based catalysts were prepared and examined for the reductive amination of triacetoneamine with n-butylamine, thereinto, Cu–Cr–La/γ-Al₂O₃ showed excellent results. The catalysts were studied by XRD, XPS, H₂-TPR and NH₃-TPD. It was found that doped Cr remarkably enhanced the activity of Cu/γ-Al₂O₃ due to better dispersion of Cu⁰, which is believed to be the active site for the reductive amination. Additionally, it was obvious that introduction of La to Cu–Cr/γ-Al₂O₃ led to a higher selectivity and longer lifetime. The reaction parameters were optimized and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine was obtained in a yield of 94%.     

An iron-based beverage, HydroFerrate fluid (MRN-100), alleviates oxidative stress in murine lymphocytes in vitro

Background  

Several studies have examined the correlation between iron oxidation and H₂O₂ degradation. The present study was carried out to examine the protective effects of MRN-100 against stress-induced apoptosis in murine splenic cells in vitro. MRN-100, or HydroFerrate fluid, is an iron-based beverage composed of bivalent and trivalent ferrates.     

Preparation of transparent Y2O3 ceramic via gel casting: Realization of high solid volume via surface modification

In this article, isocyanate was adopted to modify Y₂O₃ powder for the purpose of preparing transparent Y₂O₃ ceramics via gel casting. The modification could enhance the hydration resistance of Y₂O₃ powder through the steric hindrance effect. The coating mechanism can be proved by the infrared spectrum of the surface-modified Y₂O₃ powder. Modification could not only prevent Y₂O₃ particles from reacting with water, but also prevents agglomeration between particles. The viscosity of the slurry with a solid content of 52.7 vol% is only 0.48 Pa·s at the shear rate of 100 s⁻¹, which is suitable for preparing high-density compacts by gel casting. The transmittance of the sample (1840°C × 8 h, 1 mm thickness) at 1100 nm reaches 75%. The microstructure of the sintered body is dense with the average grain size of 6.5 μm without obvious impurities nor pores. Five mol% ZrO₂-doped Y₂O₃ transparent ceramic fairing with the diameter of 5 cm without defects was successfully fabricated by gel casting (52.7 vol% solid volume) and vacuum sintering (1840°C × 8 h).     

Persistent deNOx Ability of CaAl2O4:(Eu, Nd)/TiO2-x N y Luminescent Photocatalyst

Abstract  

CaAl₂O₄:(Eu, Nd)/TiO_2-x N _y composite luminescent photocatalyst was successfully synthesized by a simple planetary ball milling process. Improvement of photocatalytic deNOx ability of TiO_2-x N _y , together with the persistent photocatalytic activity for the decomposition of NO after turning off the light were realized, by coupling TiO_2-x N _y with long afterglow phosphor, CaAl₂O₄:(Eu, Nd). The novel persistent photocatalytic behavior was related to the overlap between the absorption wavelength of TiO_2-x N _y and the emission wavelength of the CaAl₂O₄:(Eu, Nd). It was found that CaAl₂O₄:(Eu, Nd)/TiO_2-x N _y composites provided the luminescence to persist photocatalytic reaction for more than 3 h after turning off the light.     

Synthesis of size controlled phase pure KNbO3 fine particles via a solid-state route from a core–shell structured precursor

From a core–shell structured precursor, comprising Nb₂O₅ core enveloped by KHCO₃ in an equimolar proportion, phase pure KNbO₃ (KN) fine particles were obtained by calcining in air at 600 °C for 1 h. Disintegrating the large agglomerated particles of KHCO₃ prior to the precursor preparation enabled the micronization of the KN particle size down to 240 nm, close to that of the starting Nb₂O₅, due to increased mixing homogeneity and consequent thorough enveloping of individual Nb₂O₅ particles. Based on these findings, together with the known coupling diffusion mechanism of potassium and oxygen into Nb₂O₅, it was concluded that the core–shell particles in the precursor serve as a separated reaction space to complete the formation of KN without appreciable coalescence or local sintering, as far as the firing temperature is low enough like those employed in the present study. Superiority of KHCO₃ over K₂CO₃ or KNO₃ as a potassium source was also discussed.     

Structural and physical characteristics of Au2O3-doped sodium antimonate glasses – Part I

Na₂O-Sb₂O₃ glasses doped with different concentrations of Au₂O₃ were prepared by melt quenching technique and later were heat treated at 800°C for 6 hours. Structural analysis by XRD, XPS, SEM, EDS, and DSC techniques indicated that the samples are embedded with multiple crystallites composed of Sb³⁺, Sb⁵⁺, Au³⁺ ions, and Au⁰ metallic particles. These studies have further demonstrated a gradual increasing fraction of Au⁰ metallic particles with increasing Au₂O₃ concentration. IR spectral studies suggested increasing the degree of polymerization of the glass network (due to increasing concentration of Sb⁵⁺ ions that participate in the glass network with Sb^VO₄ structural units) with rise in the concentration of Au₂O₃. Optical absorption spectra of the titled samples have exhibited a broad absorption band at about 530 nm predicted due to the surface plasmon resonance (SPR) and exhibited a spectral red shift with increasing intensity with increase in Au₂O₃ content. Photoluminescence (PL) spectra of the samples recorded (at λ_exc = corresponding SPR band position) exhibited an emission peak at about 580 nm (identified as being due to interband transition between sp and d bands of gold particles). Overall, the analysis of these results has confirmed increasing concentration of Au metallic particles with increase in Au₂O₃ content in the titled material. Finally, it is predicted that the presence of higher concentration of gold particles in the polymerized antimonate glass network makes the materials useful for designing different nano dimensional optoelectronic devices.     

Molybdenum Schiff Base Complex Covalently Anchored to Silica-Coated Cobalt Ferrite Nanoparticles as a Novel Heterogeneous Catalyst for the Oxidation of Alkenes

Abstract  

Silica-coated cobalt ferrite nanoparticles were prepared and functionalized with Schiff base groups to yield immobilized bidentate ligands. The functionalized magnetic nanoparticles were then treated with Mo (O₂)₂(acac)₂, resulting in the novel immobilized molybdenum Schiff base catalyst. The as-prepared catalyst was characterized by X-ray powder diffraction, transmission electron microscopy, vibrating sample magnetometry, thermogravimetric analysis, Fourier transform infrared, and inductively coupled plasma atomic emission spectroscopy. The immobilized molybdenum complex was shown to be an efficient heterogeneous catalyst for the oxidation of various alkenes using t-BuOOH as oxidant. This catalyst, which is easily recovered by simple magnetic decantation, could be reused several times without significant degradation in catalytic activity.     

Changes in Surface Property and Catalysis of Mesoporous Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> from Amorphous to Crystalline Pore Walls

Abstract  

The amorphous inorganic phase of an ordered amorphous mesoporous Nb₂O₅ with two dimensional hexagonal (2D-hex) structure was crystallized with maintaining the original well arranged porous structure. The difference in surface property between amorphous and crystalline Nb₂O₅ with similar ordered mesoporous structure was compared. It was found from water adsorption–desorption isotherms and observation by infrared (IR) spectroscopy that the amorphous sample was hydrophilic and that the surface OH groups were acidic. On the other hand, the OH groups on crystalline mesoporous Nb₂O₅ were non-acidic and inside the pores was less hydrophilic. The surface property was also compared by a catalytic reaction, oxidation of cyclohexe by an aqueous solution of H₂O₂. The high (95%) selectivity for 1,2-epoxycyclohexane was obtained at 40 °C for 2 h in methanol solvent over crystalline mesoporous Nb₂O₅ at 12% conversion, while amorphous mesoporous Nb₂O₅ showed high (68%) selectivity for 1,2-cyclohexanediol in acetonitrile solvent at 60 °C for 2 h at 22% conversion. The differences in selectivity and the optimal solvent between amorphous and crystalline samples were interpreted in terms of the acidic feature of surface OH groups and hydrophilicity. While similar selectivity was observed over non-porous crystalline Nb₂O₅, much higher conversion over crystalline mesoporous Nb₂O₅ was attained at the same surface area. Thus, an advantage of mesoporous structure is attributed to the higher contact time of molecules inside the pores to the catalyst surface than those outside the particles.     

Pro-inflammatory adjuvant properties of pigment-grade titanium dioxide particles are augmented by a genotype that potentiates interleukin 1β processing

Background

Pigment-grade titanium dioxide (TiO₂) particles are an additive to some foods (E171 on ingredients lists), toothpastes, and pharma?/nutraceuticals and are absorbed, to some extent, in the human intestinal tract. TiO₂ can act as a modest adjuvant in the secretion of the pro-inflammatory cytokine interleukin 1β (IL-1β) when triggered by common intestinal bacterial fragments, such as lipopolysaccharide (LPS) and/or peptidoglycan.Given the variance in human genotypes, which includes variance in genes related to IL-1β secretion, we investigated whether TiO₂ particles might, in fact, be more potent pro-inflammatory adjuvants in cells that are genetically susceptible to IL-1β-related inflammation.

Methods

We studied bone marrow-derived macrophages from mice with a mutation in the nucleotide-binding oligomerisation domain-containing 2 gene (Nod2 ^m/m), which exhibit heightened secretion of IL-1β in response to the peptidoglycan fragment muramyl dipeptide (MDP). To ensure relevance to human exposure, TiO₂ was food-grade anatase (119?±?45 nm mean diameter?±?standard deviation). We used a short ‘pulse and chase’ format: pulsing with LPS and chasing with TiO₂ +/? MDP or peptidoglycan.

Results

IL-1β secretion was not stimulated in LPS-pulsed bone marrow-derived macrophages, or by chasing with MDP, and only very modestly so by chasing with peptidoglycan. In all cases, however, IL-1β secretion was augmented by chasing with TiO₂ in a dose-dependent fashion (5–100 μg/mL). When co-administered with MDP or peptidoglycan, IL-1β secretion was further enhanced for the Nod2 ^m/m genotype. Tumour necrosis factor α was triggered by LPS priming, and more so for the Nod2 ^m/m genotype. This was enhanced by chasing with TiO₂, MDP, or peptidoglycan, but there was no additive effect between the bacterial fragments and TiO₂.

Conclusion

Here, the doses of TiO₂ that augmented bacterial fragment-induced IL-1β secretion were relatively high. In vivo, however, selected intestinal cells appear to be loaded with TiO₂, so such high concentrations may be ‘exposure-relevant’ for localised regions of the intestine where both TiO₂ and bacterial fragment uptake occurs. Moreover, this effect is enhanced in cells from Nod2 ^m/m mice indicating that genotype can dictate inflammatory signalling in response to (nano)particle exposure. In vivo studies are now merited.

     

Preparation of Fe3Si‐Al2O3 Nanocomposite Powders by Mechanochemical Reaction of Fe3O4‐Si‐Al Powder Mixtures

Phase evolution and morphology of Fe₃O₄‐Si‐Al powder mixtures during ball milling from 30 min to 20 h were investigated. A 3‐h critical milling was necessary for the occurrence of mechanically activated combustion reaction. The reaction results in the formation of Fe (Si), Fe₃Si, and α‐Al₂O₃. During ball milling from 3 to 20 h, Fe (Si) and Fe₃Si were combined into disordered Fe₃Si intermetallic and Fe₃Si‐Al₂O₃ composite powder was formed. The presence of in situ formed alumina leads to a decrease in crystallite and particle sizes. The Fe₃Si‐Al₂O₃ particles after milling for 20 h had a crystalline size of 10~12 nm.     

Effect of Ga2O3 on Sintering and Phase Stability of Sc2O3‐Doped Tetragonal Zirconia Prepared via Aqueous Solution Route

The effects of the presence of Ga₂O₃ on low‐temperature sintering and the phase stability of 4, 5, and 6 mol% Sc₂O₃‐doped tetragonal zirconia ceramics (4ScSZ, 5ScSZ, and 6ScSZ, respectively) were investigated. A series of zirconia sintered bodies with compositions (ZrO₂)_0.99?x(Sc₂O₃)_x(Ga₂O₃)_0.01, x = 0.04, 0.05, and 0.06 was fabricated by sintering at 1000°C to 1500°C for 1 h using fine powders that were prepared via the combination of homogeneous precipitation method and hydrolysis technique using monoclinic zirconia sols synthesized through the forced hydrolysis of an aqueous solution of zirconium oxychloride at 100°C for 168 h. The presence of 1 mol% Ga₂O₃ was effective in reducing sintering temperature necessary to fabricate dense bodies and enabled to obtain dense sintered bodies via sintering at 1100°C for 1 h. The phase stability, that is, low‐temperature degradation behavior of the resultant zirconia ceramics was determined under hydrothermal condition. The zirconia ceramics codoped with 1 mol% Ga₂O₃ and 6 mol% Sc₂O₃ (1Ga6ScZ) fabricated via sintering at 1300°C for 1 h showed high phase stability without the appearance of monoclinic zirconia phase, that is the tetragonal‐to‐monoclinic phase transformation was not observed in the 1Ga6ScZ after treatment under hydrothermal condition at 150°C for 30 h.