Characterization of AlPO systems,precursors of the novel basic catalyst family AlPON

XPS and DRIFTS (diffuse reflectance infrared spectroscopy) spectra of AlPO systems, formally AlPO₄-Al₂O₃, obtained by the sol-gel method have been studied in order to understand their geometric and electronic structure. Both DRIFTS and XPS demonstrate that the acidbase character of these samples depends on a structural modification. For low phosphorus content an amorphous spinel-like solid is proposed. This geometric arrangement alters the electronic density of oxide ions and phosphorus cations and hence their Lewis acid-base properties with respect to the amorphous solid having aluminium and phosphorus only in tetrahedral arrangement.     

Subcutaneous versus intravenous low-dose IL-2 therapy after autologous transplantation: results of a prospective, non-randomized study

Medorinone 5-methyl-1,6-napthyridin-2(1H)-one and some of its analogs having varying degrees of cardiotonic potency have been studied by molecular orbital and electric field mapping methods. Ground state geometries of the molecules were optimized using the MNDO molecular orbital method. Hybridization displacement charges (HDC) combined with L?wdin charges as well as Mulliken charges were used for electric field mapping around the molecules. Electric fields near the O2 site of medorinone and its analogs correlate well with their observed cardiotonic potencies. This result is in agreement with certain pharmacological models for cardiotonics.     

Gold nanoparticles on silica monospheres modified by amino groups

Silica monospheres with a diameter of 330 nm modified with aminosilane compounds of three different basicities have been prepared. Surface coverage of the silica with an organic compound leads to an increase of the point of zero charge (PZC) of the silica surface from 2.1 to 5.1, 6.5 and 7.2 values, depending on the amine used. From these silicas, gold-containing catalysts have been prepared by a deposition–precipitation method at the same pH as the PZC of the support. The best results have been obtained using 3-(Diethoxymethylsilyl) propylamine as a modifying agent, which has allowed obtaining a good dispersion of the gold particles with an average size of 3.8 nm.     

Development of a modified CVD coating process for the enhancement of the high temperature oxidation resistance of Cr2O3 and Al2O3 forming alloys

In this work, a new deposition method for coating Cr₂O₃ and Al₂O₃ forming alloys has been set up. This is a modified CVD deposition method based on the pyrolisis of an aerosol produced by an ultrasonic wave focussed on the surface of a solution containing a reactive element soluble salt that will later transform to an oxide. The deposition takes place in a reaction chamber maintained at 473 K. To test the efficiency of the deposition method, commercial AISI-304 stainless steel samples were coated directly on the mill finish surface and on a pre-formed oxide layer with lanthanum nitrate. Specimens were then oxidised at 1173 K in synthetic air atmosphere during 25 h in a thermobalance. Oxidation kinetics of coated samples was compared with that of untreated ones. The results show that coated samples improve their high temperature oxidation resistance by decreasing their parabolic rate constant by one order of magnitude. The deposition method developed proves to be an easy, cheap and efficient way of increasing the service temperature of conventional stainless steel.     

Phase assembly and electrical conductivity of spark plasma sintered CeO2–ZrO2 ceramics

Ce _x Zr_1?x O₂ (x = 0.10, 0.16 and 0.33) nanocrystalline powders were obtained by a two-step synthesis technique and sintered by spark plasma sintering (SPS). As consequence of the reduction of Ce⁴⁺ to Ce³⁺ species by carbon in the graphite environment in SPS, phase assemblies including tetragonal, monoclinic and pyrochlore phases were generated in the ceramics during the sintering process. The electrical conductivity was highly dependent on phase assembly and atmosphere (N₂, H₂ and O₂). A significant decrease in the activation energy was noticed in the ceramics with high pyrochlore content when measuring the conductivity in H₂ atmosphere, consequence of the strong reduction promoted in these ceramics during the measurement. Equal conduction behavior with similar activation energy was observed in all the ceramics when measuring in O₂ atmosphere.     

Lanthanide oxides: Thermochemical approach to hydration

The behaviour toward hydration of a series of Ln₂O₃ has been studied as a function of water pressure and temperature by means of temperature programmed decomposition measurements. Thermochemical calculations have pointed out the structural change associated in going from ytterbium to lutetium in Ln(OH)₃ to be responsible for the apparent anomalous behaviour of Lu₂O₃. On this basis generalizations about the expected behaviour along the 4f series have been considered taking into account the simple ionic model for solid lanthanide compounds.     

New redox deposition-precipitation method for preparation of supported manganese oxide catalysts

A new preparation method has been developed to produce homogeneous coatings of manganese compounds on alumina-coated monoliths by redox deposition-precipitation using acetone as solvent. The deposition is produced by reduction of manganese permanganate with ethanol. The Lewis acid sites on the alumina catalyze this reaction. Thus, the precipitation is produced preferentially on the surface of the monolith and not in the bulk of the solution. Monoliths prepared by this method are very active for the complete oxidation of oxygenated volatile organic compounds (VOCs). These monoliths consist of a mixture of complex phases including aluminum, sulfated alumina, potassium sulfate and manganese oxide.     

Renal carcinoma and von Hippel-Lindau disease

We report a case of life-threatening esophageal hemorrhage after metal stent implantation successfully treated by arterial embolization. An 85-year-old woman was admitted in shock secondary to massive hematemesis and melena. Recent medical history revealed esophageal cancer treated 8 weeks previously by endoesophageal radiotherapy (40 Gy) and endoscopic placement of a covered Wall-stent prosthesis. Selective arteriography of the fifth posterior right intercostal artery showed massive contrast extravasation in the esophagus. Embolization was performed with 150-250-micron polyvinyl alcohol particles. Follow-up at 5 months was uneventful. Arteriography and embolization are advised when severe hemorrhage occurs after esophageal implantation of metal stents.     

Antioxidant properties and shelf‐life extension of fresh‐cut tomatoes stored at different temperatures

BACKGROUND: The feasibility of using modified atmosphere packaging (5 kPa O₂ + 5 kPa CO₂) to maintain the antioxidant properties of fresh‐cut tomatoes during shelf‐life was assessed through storage at different temperatures (5, 10, 15 and 20 °C). Health‐related compounds, antioxidant capacity, microbiological counts, physicochemical parameters and in‐package atmosphere of tomato slices were determined. RESULTS: Initial lycopene, vitamin C and phenolic contents and physicochemical parameters of tomato slices were well maintained for 14 days at 5 °C. Lycopene and total phenolic contents were enhanced over time in tomato slices stored at 15 and 20 °C. However, this increase in antioxidant compounds of fresh‐cut tomatoes during storage may be associated with excessive amounts of CO₂ (R² = 0.5679–0.7328) in the packages due to microbial growth. Although keeping tomato slices at temperatures above 10 °C increased their antioxidant content, the shelf‐life of the product was reduced by up 4 days. CONCLUSIONS: A storage temperature of 5 °C is appropriate for maintaining the microbiological shelf‐life of fresh‐cut tomatoes for up to 14 days and also allows the antioxidant properties of tomato slices to be retained over this period, thus reducing wounding stress and deteriorative changes. Copyright © 2008 Society of Chemical Industry