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The preparation, structure and thermal stability of hydrogenated carbon nanotubes is described. The study concluded that both multiwall and single-wall nanotubes a well as graphite can be chemically hydrogenated via a dissolved metal reduction method in liquid ammonia.

The goal of this study was to upgrade the decomposition products of municipal solid waste applying different catalysts during slow and high heating rate pyrolysis. The municipal waste studied was a mixture of biomass and plastics in a ratio of 1:1. Different zeolites (β- and Y-zeolites, ZSM-5 and FCC catalysts) and nickel-molybdenum (NiMo/Al 2 O 3 ) catalysts were tested in order to upgrade the quality of the decomposition product mixture. The applied sample-catalyst ratio was 2:1. The evolution profiles of the gas phase decomposition products were monitored by thermogravimetry/mass spectrometry (TG/MS). The product distribution was analyzed by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) technique. The effect of the catalysts on the biomass part of the waste sample is very similar. The thermal decomposition of the plastic fraction is catalyzed mainly by β-zeolite and ZSM-5, as the thermogravimetric and the mass spectrometric data indicate. The pyrolysis results unambiguously show the cracking effects of the applied catalysts on the composition of the evolving hydrocarbon mixture. The yield of the aromatic products is increased significantly. [ABSTRACT FROM AUTHOR]

In this work, effects of storage time and conditions on the properties of one woody charcoal were studied. Prior to the storage test, the untreated charcoal was characterized by thermogravimetry/mass spectrometry (TG/MS). Weight loss (TG) and evolution profile curves of selected gaseous products were obtained from charcoal pieces that have various appearances, apparent densities and sizes. The result implies that the charcoal pieces have experienced different carbonization conditions. The charcoal samples were collected during the storage test under well controlled conditions and further characterized. It was found that the volatile content of the collected charcoal samples decreases along the storage time. The ash content of sampled charcoal only changed slightly. Accordingly, the fixed carbon content of sampled charcoal decreased about 3% in comparison to the initially loaded untreated charcoal samples. Such decrease of fixed carbon content of charcoal during storage might cause considerable reduction of profitability for an industry that consumes large amounts of charcoal at a relatively high price. [ABSTRACT FROM AUTHOR]

The catalytic effect of HZSM-5 zeolite was studied on the thermal decomposition of model waste mixtures of plastics and biomass. The influence of temperature and catalyst ratio as well as the hindering effect of cellulose and lignin on the catalytic decomposition of plastic waste was studied applying low and high heating rate by thermogravimetry/mass spectrometry (TG/MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), respectively. HZSM-5 catalyst reduced the thermal stability of plastic waste, but the catalytic effect was blocked in the presence of 50% cellulose or 10% lignin. Principal component analysis (PCA) has been applied to reveal correlations between the composition of pyrolysis products, pyrolysis temperature and proportion of the applied catalyst. The hindering effect of biomass can be compensated by applying higher catalyst ratio. [ABSTRACT FROM AUTHOR]

In this work the torrefaction of different parts of Norway spruce (stem wood, bark, and stump) was studied. Three different torrefaction temperatures were applied: 225, 275, and 300 °C with 30 and 60 minutes isothermal periods. The untreated and torrefied biomass materials were characterized by thermogravimetric analysis (TGA). The TGA results are interpreted in terms of the chemical composition determined by the cellulose, hemicellulose and Klason lignin content. The alkali ion contents of the samples were measured by ICP-OES technique. It was found that the effect of torrefaction temperature was greater than the effect of residence time up to 275 °C, while at 300 °C the residence time had a significant influence on the composition of the torrefied samples due to the intensive decomposition of cellulose. [ABSTRACT FROM AUTHOR]

Silica@zirconia@poly(malic acid) nanocarriers of 110 nm mean diameter were designed, synthesized and characterized for the targeted delivery of diagnostic and therapeutic 99mTc to folate-overexpressing tumors. An important achievement was that a multifunctional l-(−)-malic-acid-based copolymer was formed in situ at the surface of the inorganic cores in a single synthetic step incorporating l-(−)-malic acid, β-cyclodextrin rings, folic acid moieties, and polyethylene glycol chains. Morphological and in-depth structural analysis of the particles proved their core@shell structure. Stability experiments in aqueous media evidenced that stable suspensions can be obtained from the lyophilized powder in 10 mM phosphate buffer at pH 7.4. During 14-day degradation experiments, the nanoparticles were found to be slowly dissolving (including inorganic core) in saline and also in total cell medium. An in vitro toxicity assay on hepatocytes showed a concentration-dependent decrease of cell viability down to 63 ± 1% at the highest applied concentration (0.5 mg ml−1). Proof of concept experiments of technetium-99m radiolabelling and in vivo labelling stability are presented. [ABSTRACT FROM AUTHOR]

Porous, fluorescent zirconia particles of nearly 380 nm diameter were prepared without template molecules or labeling dyes. The porous structure is the result of aggregation-induced particle formation. The inherent fluorescence is assigned to coordinatively unsaturated Zr4+ ions at the sol–gel derived ZrO2 surface. After physico-chemical characterization of the native zirconia particles carboxyl and/or amine bearing drug molecules (d,l-α-difluoromethylornithine – DFMO, ursolic acid – UA and doxorubicin – DOX) were adsorbed onto their surface, and the products were analyzed with Fourier-transform infrared spectroscopy (FTIR), thermogravimetry (TG), small-angle X-ray scattering (SAXS), fluorimetry and zeta potential vs. pH measurements. We have found that DOX complexes coordinatively unsaturated Zr4+ ions without dislocating them, while carboxyl-bearing drugs interact with basic surface Zr–OH sites eliminating some of the carbonate species. The adsorption of UA at the zirconia surface shifts considerably the isoelectric point of the surface and thus provides kinetic stability to the particles at physiological pH. An in vivo biodistribution study in two healthy dogs performed by SPECT/CT detection after 99mTc labeling of the nanocarriers has shown the possibility of drug delivery application. [ABSTRACT FROM AUTHOR]

In last few years enterococcal strains are handled with a special care due to their increasing role in nosocomial infections and for remarkable evolution of their resistance mechanisms against antimicrobial agents. Vancomycin had been considered a last resort drug in the treatment of β-lactam-resistant enterococcal infections. Vancomycin-resistant E. faecium (VREF) strains represent a serious threat in health assistance-related infections, because of the complexity and cost of the treatment. Most of VREF strains from USA were isolated from hospitals, but in Europe, majority of isolates are originally from community and animal farms. In this study seven local E. faecium strains isolated from Cluj-Napoca city's sewage plant were analyzed. Antimicrobial resistance of the isolated strains was determined with conventional and molecular methods using microdilution and PCR amplification of the vanA and vanB genes. The minimal inhibitory concentration values (MICs) are between 8 and 256 µg/ml. The amplified fragments migrated according to the expected size of the vanA gene (732 bp), but in case of vanB gene no amplification was detected, being a certain method for detection of vancomycin-resistant enterococci from sewage. [ABSTRACT FROM AUTHOR]

We present sidewall functionalization of carbon nanotubes via various dissolving metal reduction methods. Carbanion complexes of lithium were prepared in liquid ammonia and THF and reacted with a series of alkyl and aryl halogenides, as well as methanol resulting in the formations of alkylated, arylated, and hydrogenated nanotube derivatives, respectively. The hydrogenation reactions were also performed on graphite. Thermal stabilities and chemical compositions were determined by thermogravimetry-mass spectrometry (TG-MS). Characteristic decomposition peaks, observed in the range of 350-600° C, suggest the formation of covalent derivatives upon functionalization. The compositions are 0.01-0.25 side group/carbon depending on the materials. NMR and Raman spectroscopic characterizations show the structural changes due to functionalization. [ABSTRACT FROM AUTHOR]