Sol–gel immobilized aryl iodides for the catalytic oxidative α-tosyloxylation of ketones

New hybrid silica materials M1–M4, derived from mono and bis-silylated aryl iodides, have been prepared via sol–gel processes, either by the hydrolytic polycondensation of a bis-silylated monomer or by the co-gelification of a monosilylated precursor with tetraethylorthosilicate. They have been fully characterized by elemental analysis, ¹³C and ²⁹Si CP-MAS solid state NMR, IR, TGA, and nitrogen-sorption measurements. These organosilicas have been successfully applied as supported catalysts in the α-tosyloxylation of aliphatic ketones in the presence of m-chloroperbenzoic acid (m-CPBA) as an oxidant, with the corresponding α-tosyloxyketones obtained in moderate to good isolated yields. The recyclability of the supported catalysts by a simple filtration has also been investigated.     

In vivo preliminary evaluation of bone-microcrystalline and bone-nanocrystalline diamond interfaces

Chemical vapor deposited diamond is a new potential biomedical material which has the advantage of chemical inertness, extreme hardness and low coefficient of friction, among others. In orthopedics and maxillofacial surgery, these properties could improve implant performance, reducing metallic corrosion, particle wear, inflammatory reactions and bone loss. In the present study, two types of chemical vapor deposition (CVD) diamonds have been analyzed: microcrystalline diamonds (MD) and nanocrystalline diamonds (ND), both produced by hot-filament chemical vapor deposition. The diamond tubes were previously characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman scattering spectroscopy (RSS). The aim of this study was to verify the interface between bone and MD and ND, surgically implanted in the femoral diaphysis of Wistar rats, after 4 and 8 weeks. The outcome was evaluated by scanning electron and optical microscopy using a semi quantitative method. The results suggest that nanocrystalline diamonds (ND) elicits a richer biological response than microcrystalline diamonds (MD) when in interaction with bone.     

Analysis of the Drying Processes of Osmotically Dehydrated Apple Using the Characteristic Curve Model

ABSTRACT

Round slices (2 mm thick) of fresh apple and of apple subjected to osmo-dehydration processes in sucrose syrups until reaching a_w values of 0.979, 0.968. and 0.958. were air-dried at 50. 60. and 70°C. Analysis of the drying curves showed that the products do not present a constant rate period (except for fresh apple) but showed two falling rate periods. Initial a_w greatly affects the fraction of water lost during the drying processes. The use of the Fick's Second Law was not adequate to describe the experimental drying curves. However, apple drying processes can be modeled by the Characteristic Drying Curve model, using several equations (polynomial and logarithmic) with a high confidence level. The parameters of each equation showed a great dependence on product's a_w These models can be used to predict drying curves within the studied limits in each case, presenting great advantages when compared to classical models based on effective diffusion coefficients.     

All the Truth About NEvAr

The use of Evolutionary Computation approaches to generate images has reached a great popularity. This led to the emergence of a new art form—Evolutionary Art—and to the proliferation of Evolutionary Art Tools. In this paper, we present an Evolutionary Art Tool, NEvAr, the experimental results achieved, and the work methodology used to generate images. In NEvAr, useful individuals are stored in a database in order to allow their reuse. This database is playing an increasingly important role in the creation of new images, which led us to the development of automatic seeding procedures, also described. The automation of fitness assignment is one of our present research interests. We will, therefore, describe some preliminary results achieved with our current approach to automatic evaluation.     

Synthesis and evaluation of organosilicon inhibitors of active purine transport in human osteoblasts

In the search for new compounds that might, once incorporated into biomaterials, stimulate the natural processes of bone regeneration, a new series of silicon-containing alkyl nucleobase analogues has been synthesized. An active hypoxanthine transport process in human osteoblasts was demonstrated, with an apparent Michaelis constant of 2.3 microM and a maximum possible rate of 0.47 pmol s(-1) x 10(6) cell. The synthesized analogues were tested for toxicity in human osteoblasts. Nontoxic analogues were tested in competition transport studies with [(14)C]hypoxanthine. Two of them were found to inhibit the active transport of hypoxanthine in human osteoblasts, with IC(50) values of 6.5 and 11.6 microM.     

Collision-induced dissociation studies of poly(vinylidene) fluoride telomers in an electrospray-ion trap mass spectrometer

Although fluorinated polymers are widely used in different applications, they are rarely investigated by "soft ionization" techniques such as matrix-assisted laser desorption/ionization and electrospray ionization (ESI). We report here, the desorption and fragmentation of poly(vinylidene) fluoride (PVDF) telomers in an ion trap mass spectrometer coupled to an ESI source. Protonated and lithiated telomers under collision-induced dissociation resonant excitation show mainly HF losses. Fragmentation of protonated telomers can be rationalized by a double proton-transfer mechanism and that of lithiated and anionic telomers by an ion-dipole mechanism. Both mechanisms predict the formation of a stable aromatic or a linear conjugated species, respectively. For lithiated telomers, we could determine the degree of polymerization (n) from the product ion abundance in MS2 experiments. The nature of the end group plays a substantial role in orienting the fragmentation of the PVDF ions. It is interesting to note that, in MS2 experiments, Li+ and F- act as catalysts in the fragmentation of PVDF telomers. Fragmentation of the PVDF telomer backbone was not observed under any experimental conditions.     

Unique individual or interchangeable group member? The accentuation of intragroup differences versus similarities as an indicator of the individual self versus the collective self.

In 4 studies, the authors examined antecedents of self-definition as either a unique individual (the individual self) or an interchangeable group member (the collective self). Accentuation of perceived similarities versus differences among in-group members including the self served as the main indicator of participants' relative emphasis on their individual or collective self. Following prior work in the social identity and self-categorization theory tradition, the authors predicted and found systematic variations in the relative emphasis on the individual or collective self. Relative emphasis varied with the valence of temporarily salient in-group features, with the more stable or chronic attractiveness of one's in-group, and with awareness of special treatment of the in-group by the outside world. Finally, issues are discussed concerning the cognitive construal of in-groups as well as the role of the individual self and the collective self for strategies of social mobility and social change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In-stream nitrogen attenuation: model-aggregation effects and implications for coastal nitrogen impacts

Eutrophication problems in coastal and marine waters worldwide emphasize the significance, for the scientific community as well as the whole society, of relevant quantification of catchment-scale nitrogen transport from land to coast. Different catchment-scale nitrogen budget models use, and base management recommendations on, quite different process representations of and spatial resolution approaches to in-stream nitrogen attenuation. We compare three different spatial resolution approaches to modeling nitrogen loss rates in streams of the same drainage basin. Results show that commonly used spatial model aggregation may lead to artificial decrease of calibrated nitrogen loss rates with increasing stream depth (or flow), in addition to any such dependences that may prevail in independently measurable reality. Coastal nitrogen impact predictions and practical management implications of large-scale model aggregation of nitrogen attenuation rates may further differ considerably from those based on rates from finer resolution modeling or independent measurements.