Palladium nanoparticles supported on an organic-inorganic fluorinated hybrid material. Application to microwave-based heck reaction

Phosphine-free palladium nanoparticles were embedded in a fluorous organic-inorganic hybrid material 6b prepared by the sol-gel process. The use of Pdn.6b in the Heck coupling reaction under microwave irradiation has been investigated. Recycling studies have shown that the catalyst can be readily recovered and reused several times without significant loss of activity. Reactions and recovery of the solid-supported palladium catalyst system can be carried out in the presence of air, without any particular precaution.     

Impact of productivity on cross-training configurations and optimal staffing decisions in hospitals

Cross-training of nursing staff has been used in hospitals to reduce labor cost, provide scheduling flexibility, and meet patient demand effectively. However, cross-trained nurses may not be as productive as regular nurses in carrying out their tasks because of a new work environment and unfamiliar protocols in the new unit. This leads to the research question: What is the impact of productivity on optimal staffing decisions (both regular and cross-trained) in a two-unit and multi-unit system. We investigate the effect of mean demand, cross-training cost, contract nurse cost, and productivity, on a two-unit, full-flexibility configuration and a three-unit, partial flexibility and chaining (minimal complete chain) configurations under centralized and decentralized decision making. Under centralized decision making, the optimal staffing and cross-training levels are determined simultaneously, while under decentralized decision making, the optimal staffing levels are determined without any knowledge of future cross-training programs. We use two-stage stochastic programming to derive closed form equations and determine the optimal number of cross-trained nurses for two units facing stochastic demand following general, continuous distributions. We find that there exists a productivity level (threshold) beyond which the optimal number of cross-trained nurses declines, as fewer cross-trained nurses are sufficient to obtain the benefit of staffing flexibility. When we account for productivity variations, chaining configuration provides on average 1.20% cost savings over partial flexibility configuration, while centralized decision making averages 1.13% cost savings over decentralized decision making.     

Silica nanostructures against fungal growth: design and preparation of antifungal cotton fabrics

Cellulose - The preparation of antifungal-functionalized silica nanoparticles by covalent attachment of several silylated derivatives based on the topical antifungal agent Micozanole is described....     

An FT-IR study of sarcoplasmic reticulum solubilization by triton X-100

Low concentrations of the non-ionic detergent Triton X-100 increase the activity of sarcoplasmic reticulum Ca⁺⁺-ATPase without major changes in protein conformation, according to FT-IR spectroscopy in H₂O and D₂O. At higher surfactant concentrations the enzyme activity is inhibited, while changes in protein conformation are seen: The proportion of unordered structure increases at the expenses of-turns and parallel-sheet.     

Influence of barium source on the characteristics of sol-precipitated BaTiO<Subscript>3</Subscript> powders and related ceramics

In order to obtain pure and fine BaTiO₃ powders with controlled morphology, sol-precipitation methods involving the use of titanium iso-propoxide and of two different barium sources, i.e. barium nitrate and barium acetate, were proposed in this work. The thermal behaviour of the synthesized gels and the X-ray diffraction data obtained for the oxide powders pointed out that, by using Ba(NO₃)₂ as barium source, the decomposition process was completed at lower temperature (750°C) and was accompanied by a more pronounced tendency to obtain a single phase BaTiO₃ composition, by comparison with the synthesis where barium acetate was used as raw material (1100°C). Scanning electron microscopy investigations emphasized the effect of the nature of barium source and synthesis conditions on the morphology of the oxide powders, as well as on the microstructure of the related ceramics.     

Domain Formation in DODAB–Cholesterol Mixed Systems Monitored via Nile Red Anisotropy

The effect of the cholesterol (ch) on liposomes composed of the cationic lipid dioctadecyldimethylammonium bromide (DODAB) was assessed by studying both the steady-state and time-resolved fluorescence anisotropy of the dye Nile Red. The information obtained combined with analysis of the steady-state emission and fluorescence lifetime of Nile Red (NR) for different cholesterol concentrations (5–50%) elucidated the presence of “condensed complexes” and cholesterol-rich domains in these mixed systems. The steady-state fluorescence spectra were decomposed into the sum of two lognormal emissions, emanating from two different states, and the effect of temperature on the anisotropy decay of Nile Red for different cholesterol concentrations was observed. At room temperature, the time-resolved anisotropy decays are indicative of NR being relatively immobile (manifest by a high r _∞ value). At higher temperature, rotational times ca. 1 ns were obtained throughout and a trend in increasing hindrance was seen with increase of Ch content.     

Enantioselective vicinal bis-acylation of olefins

A two-step sequence for the asymmetric vicinal acylation of olefins by a [2+2+1] strategy is reported. The key reaction is a [2+2] cycloaddition of an olefin to a chiral keteniminium salt derived from N-tosylsarcosinamide. This is followed by a regioselective Baeyer-Villiger oxidation of the resulting cyclobutanone to yield a lactol derivative that is equivalent to the product of addition of a carboxyl and a carbonyl group to the olefin. N-Tosylsarcosinamides derived from prolinol methyl ether and 2,5-dimethylpyrrolidine gave the best yields and diastereoselectivities. Five- and six-membered cycloolefins only gave cis products as expected. With seven- and eight-membered rings and cis 1,2-disubstituted acyclic olefins, partial or complete epimerisation of the cis to the trans adducts was observed. Facial selectivities were generally good except for terminal olefins. The oxidation step proceeded in high yields to give crystalline compounds which could usually be obtained in enantiopure form by simple recrystallisation.     

Fluorous gallic acid derivatives as versatile gelators. Self-assembly into nanosized fibers or balls

A new class of low molecular mass organogelators, the fluorous derivatives of gallic acid 1–3, is described. The gelation properties have been examined in a large variety of organic liquids. The corresponding analogs possessing alkyl instead of semiperfluoroalkyl chains (4–6) do not display any gelation properties, thus revealing the key role of perfluorinated chains in the aggregation/gelation process. Gels have been studied by scanning electron microscopy, revealing the presence of three-dimensional networks of nanosized fibers. In the case of an instable gel, SEM images showed that these elongated fibers curl up into nanoballs, failing to create the entangled network responsible for solvent entrapment.     

Desktop near-field thermal-lens microscope for thermo-optical detection in microfluidics

A new compact near-field desktop-sized diode laser thermal-lens microscope for analysis in microfluidics was proposed. A novel beam-alignment and detection systems provided high signal stability and, along with reduced number of optical elements rendered the instrument portable. The detection of nonfluorescent model species (Fe(II)-bathophenanthroline chelate) in water showed good linearity in the range of 5 × 10(-9) to 1 × 10(-4) M, and the limit of detection was 3.5 × 10(-9) M, which corresponded to 3.5 × 10(-7) absorbance units and provided a 20-fold enhancement in sensitivity compared with existing schematic.