328 research outputs found

    Ultrashort pulsed laser conditioning of human enamel: in vitro study of the influence of geometrical processing parameters on shear bond strength of orthodontic brackets

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    [Abstract] The surfaces of 63 extracted premolar teeth were processed with intense ultrashort laser pulses (λ = 795 nm; pulse duration, 120 fs; repetition rate, 1 kHz) to produce cross patterns with different pitches (s) in the micrometer range in order to evaluate the influence of such microstructures on the shear bond strengths of orthodontic brackets to enamel. The samples were classified in nine groups corresponding to the control group (raw samples) and eight different laser-processed groups (cross patterns with s increasing from 15 to 180 μm). Brackets were luted with TransbondTM XT adhesive resin to all the samples; after 72 h, they all were submitted to strength test in a universal testing machine. Additionally, a third of the samples underwent morphological analysis of the debonded surface by means of scanning electron microscope microscopy and an analysis of the failure mode based on the adhesive remnant index. The results showed that enamel microstructuring with ultrashort laser pulses remarkably increase the bond strength of brackets. Dense cross patterns (s  90 μm) give rise to smaller improvements of the bond strength. A strong correlation of this behavior with the predominant failure mode in both scenarios was found. So far, the best compromise between suitable adhesive efficiency, processing time minimization, and enamel surface preservation suggests the performance of cross patterns with pitches in the order of 90 μm.Ministerio de Economía y Competitividad; CSD2007-00013Ministerio de Economía y Competitividad; FIS2009-0952Castilla y León. Junta; SA086A12-

    Magnetic Janus micromotors for fluorescence biosensing of tacrolimus in oral fluids

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    Tacrolimus (FK506) is a macrolide lactone immunosuppressive drug that is commonly used in transplanted patients to avoid organ rejection. FK506 exhibits high inter-and intra-patient pharmacokinetic variability, making monitoring necessary for organ graft survival. This work describes the development of a novel bioassay for monitoring FK506. The bioassay is based on using polycaprolactone-based (PCL) magnetic Janus micro motors and a recombinant chimera receptor that incorporates the immunophilin tacrolimus binding protein 1A (FKBP1A) tagged with Emerald Green Fluorescent Protein (EmGFP). The approach relies on a fluorescence competitive bioassay between the drug and the micromotors decorated with a carboxylated FK506 toward the specific site of the fluorescent immunophilin. The proposed homogeneous assay could be performed in a single step without washing steps to separate the unbound receptor. The proposed approach fits the therapeutic requirements, showing a limit of detection of 0.8 ng/mL and a wide dynamic range of up to 90 ng/mL. Assay selectivity was evaluated by measuring the competitive inhibition curves with other immunosuppressive drugs usually co-administered with FK506. The magnetic propulsion mechanism allows for efficient operation in raw samples without damaging the biological binding receptor (FKBP1A-EmGFP). The enhanced target recognition and micromixing strategies hold considerable potential for FK506 monitoring in practical clinical use.Ministerio de Ciencia e InnovaciónComunidad de Madri

    Radon exhalation from uranium tailings. Comparison of experimental and theoretical data

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    Two different experimental methods and a theoretical approach are used to calculate 222Rn fluxes in the soil-atmosphere interface. As a common experimental procedure, an open-faced 30 liters cylindrical container was inverted and placed onto the tailing surface with the open face down. After a 24 h period, to balance any possible disturbance, the interior air was analysed. One of the experimental methods is based on integrated 222Rn measurements of the accumulated air-gas mixture, using solid nuclear track detectors placed inside the container. The other method is based on spot air samples using scintillation cells, being the 222Rn concentration measured in equilibrium. The radon flux theoretical values are estimated from the 226Ra content of the tailings material, determined by gamma spectrometry, and using the diffusion equation. The series of results obtained by the referred methods were compared

    Aggregation of Cyclodextrins: Fundamental Issues and Applications

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    The aggregation of cyclodextrins (CD) in aqueous solution is an old, yet still vastly unexplored topic that has been studied at least since the 1980s. At that time, few authors took into consideration the possibility of formation of aggregates for the interpretation of thermodynamic and thermophysical properties of CDs in aqueous solution. The aggregates appear at quite low CD concentrations and seem to encompass only a small number of CD molecules. They also occur in water in the presence of hydrophobic or amphiphilic moieties, including surfactants, assuming a preassembled state with the hydrophobic chains threading through one or two CDs. After a long period in which it has been neglected, CD aggregation is now a hot topic and one far from gathering consensus. In this chapter, a timely and critical review on the phenomenon of CD aggregation and the respective supramolecular properties, including some computational rationales, will be presented. A comprehensive summary of CD aggregates studied to date, indicating the formation conditions, characterization techniques, and applications, is also provided

    Use of in vivo-induced antigen technology to identify bacterial genes expressed during solea senegalensis infection with Photobacterium damselae subsp. piscicida

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    The marine fish pathogen Photobacterium damselae subsp. piscicida (Phdp) is responsible for important outbreaks affecting several fish species including flatfish Solea senegalensis. The aim of this work was to identify in vivo-induced expressed immunogenic proteins using pooled sera from fish that have experienced photobacteriosis. In vivo induced immunogenic proteins included inosine-5'-monophosphate dehydrogenase (Impdh) and alkyl hydroperoxide reductase (AhpC), two proteins involved in peptide synthesis: serine hydroxymethyl transferase (Shmt) and alanyl-tRNA synthetase (AlaRS) and the non-ribosomal peptide synthetase involved in the synthesis of the siderophore piscibactin (Irp2)
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