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•Electron spin polarization is an important property of photoexcited triplet states.•The initial spin polarization of phosphorus(V) porphyrins varies with substituents.•Net polarization develops as a result of the dynamic Jahn–Teller effect.•Net polarization is crucial for the polarization of distant radicals.

Slurry processes combine the advantages of hydrogen addition with carbon rejection in the refinement of petroleum. The process involves hydrocraking at a high temperature and hydrotreatment at a lower temperature. Catalysts are added to increase the rate of reaction, decrease reaction severity, inhibit coke deposition and improve product quality. Most of the catalysts are transition metals combined with phosphorus. The reaction efficiency also depends on pressure and temperature. A brief description of different refining processes is given.

The heterogenization of 2,6-dimethylarylimido–vanadium(V) dichloride via chemical tethering on insoluble silica supports is reported. The effects of the silica particle size, drying conditions, and the reaction time were investigated. The drying conditions of the support were found to be a crucial parameter: drying temperatures over 400 °C were needed to achieve successful catalysis. The supported catalytic systems were characterized by Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscopy–energy-dispersive X-ray (TEM-EDX), and inductively coupled plasma mass spectroscopy (ICP-MS), while the polymers were characterized by FT-IR, differential scanning calorimetry (DSC), and rheology. Ethylene polymerization tests were performed employing the prepared heterogenized catalysts with methylaluminoxane/diethylaluminum chloride as a cocatalyst. The supported catalyst precursor, when activated with diethylaluminum chloride, promotes the synthesis of polyethylene with seemingly controlled particle size in the absence of reactor fouling, suggesting the successful immobilization of the complex over the inert support. The resulting polymer shows features of ultrahigh-molecular-weight polyethylene (UHMWPE). These findings present a proof-of-concept for a new approach toward the heterogenization of arylimido–vanadium complexes.

Abstract

Under the action of near-infrared radiation, shape anisotropic gold nanoparticles emit two-photon luminescence and release heat. Accordingly, they have been proposed for imaging, photothermal therapies and thermo-controlled drug delivery. In all these applications particular care must be given to control the nanoparticle – cell interaction and the thermal efficiency of the nanoparticles, while minimizing their intrinsic cytotoxicity. We present here the characterization of the cell interaction of newly developed branched gold nanostars, obtained by laurylsulfobetaine-driven seed-growth synthesis. The study provides information on the size distribution, the shape anisotropy, the cellular uptake and cytotoxicity of the gold nanostars as well as their intracellular dynamic behavior by means of two-photon luminescence imaging, fluorescence correlation spectroscopy and particle tracking. The results show that the gold nanostars are internalized as well as the widely used gold nanorods and are less toxic under prolonged treatments. At the same time they display remarkable two-photon luminescence and large extinction under polarized light in the near-infrared region of the spectrum, 800–950 nm. Gold nanostars appear then a valuable alternative to other elongated or in-homogeneous nanoparticles for cell imaging.

The total conversion of the oil barrel to good quality fuels and distillates has been an overriding goal in the oil refinery industry. Today, it is even more important to improve the effective use of the energy fossil reserves. The actual technologies still produce variable amounts of low quality fractions (e.g.fuel oil, bunker oil) or by-products (e.g.coke). The evolution of the slurry hydrocracking technology can open the way to achieve the objective. This technology was originally developed in Germany in the first half of the last century and reconsidered by several research groups in the past decades. The catalyst used in the slurry process is still constituted by the same materials developed by German scientists in the last century, i.e.bulk, crystalline, nano-sized iron, molybdenum or tungsten sulfide. We have demonstrated now that it is possible to improve the catalytic performances by combining the excellent hydrogenation, hydrodesulfurization and hydrodemetallation properties of dispersed MoS2catalyst with those of a conventional cracking catalyst. This dual catalyst system demonstrates for the first time the ability of dispersed MoS2particles to protect the cracking catalyst against rapid decay due to coke accumulation and metal poisoning.

The focus of this article is an examination of the clinical guides' views and their role in student nurses' learning. The descriptive survey was conducted in July-September 2006. The sample was composed of 120 clinical guides who answered a questionnaire regarding the last student nurses' clinical practice experience during 2006. Clinical guides are nurses working in the wards who are available to supervise the clinical practice of nursing students, similar to preceptors in the United States. Clinical guides used different teaching strategies to stimulate students in various activities. The study revealed that the role of clinical guide is very important for the students as they develop into professional nurses.