Holmium Nanoparticles: Preparation and In Vitro Characterization of a New Device for Radioablation of Solid Malignancies

# The Author(s) 2010. This article is published with open access at Springerlink.com Purpose The present study introduces the preparation and in vitro characterization of a nanoparticle device comprising holmium acetylacetonate for radioablation of unresectable solid malignancies. Methods HoAcAc nanoparticles were prepared by dissolving holmium acetylacetonate in chloroform, followed by emulsification in an aqueous solution of a surfactant and evaporation of W. Bult: R. Varkevisser: P. R. Luijten: A. D. van het Schip

The role of tungsten oxide in the selective hydrogenolysis of glycerol to 1,3-propanediol over Pt/WO x /Al 2 O 3

Bi-functional heterogeneous catalysts combining a noble metal with an oxophilic metal (mainly W or Re) were reported to be selective for the CO hydrogenolysis of glycerol to the high added-value 1,3-propanediol. Despite intensive research work carried out, there is a great deal of controversy about the role of the oxophilic metal. In this work, the hydrogenolysis of glycerol over Pt/WOx/Al2O3 catalysts was studied in real time by in-situ attenuated total reflection infrared (ATR-IR) spectroscopy. Moreover, ex-situ ATR-IR spectroscopic studies were also used to study the interactions between glycerol and the different catalytic surfaces. The results obtained indicate a stronger adsorption of glycerol through the primary hydroxy group/s when tungsten oxides are grafted onto the γ-Al2O3 support. The competitive adsorption between the reactant and the main reaction products for the same active sites, and the effect of the hydrogen availability were also studied. The evidences found in this work point out a triple role of tungsten oxide in the reaction, acting as: (i) a strong anchoring site for the primary hydroxy group/s of glycerol, (ii) a supplier of protons, and (iii) a stabilizer of the secondary carbocation. Under the best conditions, a remarkable high yield of 1,3-propanediol of 38.5% was obtained after only 4 h of reaction time

The role of tungsten oxide in the selective hydrogenolysis of glycerol to 1,3-propanediol over Pt/WO x /Al 2 O 3

Bi-functional heterogeneous catalysts combining a noble metal with an oxophilic metal (mainly W or Re) were reported to be selective for the CO hydrogenolysis of glycerol to the high added-value 1,3-propanediol. Despite intensive research work carried out, there is a great deal of controversy about the role of the oxophilic metal. In this work, the hydrogenolysis of glycerol over Pt/WOx/Al2O3 catalysts was studied in real time by in-situ attenuated total reflection infrared (ATR-IR) spectroscopy. Moreover, ex-situ ATR-IR spectroscopic studies were also used to study the interactions between glycerol and the different catalytic surfaces. The results obtained indicate a stronger adsorption of glycerol through the primary hydroxy group/s when tungsten oxides are grafted onto the γ-Al2O3 support. The competitive adsorption between the reactant and the main reaction products for the same active sites, and the effect of the hydrogen availability were also studied. The evidences found in this work point out a triple role of tungsten oxide in the reaction, acting as: (i) a strong anchoring site for the primary hydroxy group/s of glycerol, (ii) a supplier of protons, and (iii) a stabilizer of the secondary carbocation. Under the best conditions, a remarkable high yield of 1,3-propanediol of 38.5% was obtained after only 4 h of reaction time

Shell decoration of hydrothermally obtained colloidal carbon spheres with base metal nanoparticles

The preparation of base metal nanoparticles supported on the shell of colloidal carbon spheres (CCS) is reported. Hydrothermal treatment of a sucrose solution gave conglomerates of ca. 30 μm of CCS (diameter 2-8 μm), which consist of a hydrophobic core with a hydrophilic shell due to the presence of oxygen containing functional groups. The CCS were loaded by wet impregnation with various metal salts (copper, nickel, cobalt, iron). Subsequent pyrolysis under inert conditions at T = 800 °C led to the carbothermal reduction of the impregnated metal salts by the support material. The base metal nanoparticles (size ca. 35-70 nm) are supported on the circumference of the CCS in line with its core-shell structure. Moreover, in the case of nickel, cobalt and iron nanoparticles, all capable of forming metastable metal carbides, the carbonised shells are converted into nanostructures of graphitic carbon, viz., catalytic graphitisation occurs. The spheres were characterised by scanning- and transmission electron microscopy, X-ray diffraction, Raman spectroscopy, elemental analysis, infrared spectroscopy and thermogravimetric analysis

Gold on Different Manganese Oxides : Ultra-Low-Temperature CO Oxidation over Colloidal Gold Supported on Bulk-MnO2 Nanomaterials

Nanoscopic gold particles have gained very high interest because of their promising catalytic activity for various chemicals reactions. Among these reactions, low-temperature CO oxidation is the most extensively studied one due to its practical relevance in environmental applications and the fundamental problems associated with its very high activity at low temperatures. Gold nanoparticles supported on manganese oxide belong to the most active gold catalysts for CO oxidation. Among a variety of manganese oxides, Mn2O3 is considered to be the most favorable support for gold nanoparticles with respect to catalytic activity. Gold on MnO2 has been shown to be significantly less active than gold on Mn2O3 in previous work. In contrast to these previous studies, in a comprehensive study of gold nanoparticles on different manganese oxides, we developed a gold catalyst on MnO2 nanostructures with extremely high activity. Nanosized gold particles (2-3 nm) were supported on α-MnO2 nanowires and mesoporous β-MnO2 nanowire arrays. The materials were extremely active at very low temperature (-80 °C) and also highly stable at 25 °C (70 h) under normal conditions for CO oxidation. The specific reaction rate of 2.8 molCO·h(-1)·gAu(-1) at a temperature as low as -85 °C is almost 30 times higher than that of the most active Au/Mn2O3 catalyst

Base Metal Catalyzed Graphitization of Cellulose: A Combined Raman Spectroscopy, Temperature-Dependent X‑ray Diffraction and High-Resolution Transmission Electron Microscopy Study

Microcrystalline cellulose (MCC) spheres homogeneously loaded with the nitrate salts of copper, nickel, cobalt, or iron are excellent model systems to establish the temperature at which highly dispersed base metal nanoparticles are formed as well as to establish the temperature at which catalytic graphitization occurs during pyrolysis in the temperature regime <i>T</i> = 500–800 °C. Temperature-dependent X-ray diffraction (TD-XRD) and high-resolution transmission electron microscopy (HRTEM) showed that the base metal nanoparticles are smoothly formed from related base metal oxides via carbothermal reduction (fcc copper, <i>T</i> < 500 °C; fcc nickel, <i>T</i> < 500 °C; fcc cobalt, <i>T</i> = 570 °C; bcc iron, <i>T</i> = 700 °C). Moreover, it is shown that at distinct temperatures nickel (<i>T</i> ≥ 800 °C), cobalt (<i>T</i> ≥ 800 °C), and iron (<i>T</i> ≥ 715 °C) nanoparticles catalyze the conversion of the amorphous carbon support into ribbons of turbostratic graphitic carbon according to Raman spectroscopy and TD-XRD. Copper, however, was found to be inactive. Furthermore, HRTEM revealed that nickel (500 °C ≤ <i>T</i> < 800 °C) and cobalt nanoparticles (700 °C ≤ <i>T</i> < 800 °C) after their initial formation become encapsulated by graphite-like shells prior to the onset of catalytic graphitization. This does not occur in the presence of iron nanoparticles. This distinction is attributed to the temperature required to access iron nanoparticles by carbothermal reduction and their concomitant mobility. Evidence (HRTEM) is provided that for the onset of catalytic graphitization nickel and cobalt nanoparticles first have to escape from their graphite-like shells. Therefore, iron nanoparticles are the most active catalyst. Our results further show that (metastable) metal carbides play a pivotal role in catalytic graphitization. This is demonstrated by the inactivity of copper nanoparticles, the distinct onset temperatures of catalytic graphitization, and the identification of cementite in the case of iron nanoparticles

The effect of iron catalyzed graphitization on the textural properties of carbonized cellulose: Magnetically separable graphitic carbon bodies for catalysis and remediation

Whereas pyrolysis of pristine microcrystalline cellulose spheres yields nonporous amorphous carbon bodies, pyrolysis of microcrystalline cellulose spheres loaded with iron salts leads to the formation of magnetically separable mesoporous graphitic carbon bodies. The microcrystalline cellulose spheres loaded with either iron(III) nitrate, ammonium iron(III) citrate or iron(III) chloride were pyrolyzed up to 800 °C. Temperature dependent X-ray diffraction analysis shows that the iron salts are transformed into iron oxide nanoparticles; their size and distribution are influenced by the anion of the iron salt. The iron oxide nanoparticles are subsequently carbothermally reduced by the amorphous carbon that is obtained from the pyrolysis of the microcrystalline cellulose. Next, the iron nanoparticles catalyze the conversion of the amorphous carbon to graphitic carbon nanostructures as shown with XRD, electron microscopy and Raman spectroscopy. The extent of graphitization depends on the iron nanoparticle size. Nitrogen physisorption measurements show that this graphitization process introduces mesopores into the carbon bodies. The benefits of the properties of the resulting carbon bodies (ferromagnetic character, graphitic content, mesoporosity) are discussed in connection with applications in liquid-phase catalysis and remediation