We present a programmable microcontroller-driven injection system for the exchange of imaging medium during atomic force microscopy. Using this low-noise system, high-resolution imaging can be performed during this process of injection without disturbance. This latter circumstance was exemplified by the online imaging of conformational changes in DNA molecules during the injection of anticancer drug into the fluid chamber.
A new hydrothermal route for preparing biphasic calcium phosphate monoliths is proposed. Firstly, a slurry of beta-tricalcium phosphate/ortho-phosphoric acid (b-TCP/H3PO4) is cast into the desired final shape and size to obtain a block composed of dicalcium phosphate dihydrate (DCPD) and b-TCP. This block is then treated in 1.0 M Na2HPO4 at 60 °C in order to hydrolyze the DCPD into Ca10-x(HPO4)x(PO4) 6-x(OH)2-x (CDHA) and Ca8H2(PO4)6 .5H2O (OCP). The result is a monolithic piece which preserves the initial shape and size, but which is composed instead of CDHA, OCP, and b-TCP. During the initial stage, when the pH is slightly alkaline, the product of DCPD hydrolysis is CDHA. However, when a neutral or slightly acidic pH is reached OCP is formed. Test samples processed by this method showed complete conversion of DCPD into CDHA and OCP after 112 h of hydrolysis, and with a compressive strength of 16.2 MPa, similar to cancellous bone
Novel composites of poly(methyl methacrylate) with silanized micro and nanohydroxyapatite (HA) particles were prepared. Coralina® HA was the MicroHA filler and synthetic NanoHA was the reinforcement. The influence of the total inorganic content and the proportion of micro‐ to NanoHA on the setting properties (i.e., setting time and peak polymerization temperature), compressive strength, and in vitro bioactivity in simulated body fluid (SBF) was analyzed. The novel composites exhibited appropriate handling properties. Compressive strength ranged between 71.30 ± 0.04 and 80.0 ± 2.4 MPa. The peak polymerization temperatures varied from 44.5 ± 0.5 to 50.8 ± 1.8°C, and thus complying with the ISO 5833 standard. The composites exhibited excellent calcium phosphate deposition in SBF and those with 30 wt% inorganic content showed no cytotoxicity on L929 fibroblastic cells. These results encourage further testing of these novel composites for potential future use in human health applications. POLYM. COMPOS., 34:1927–1937, 2013. © 2013 Society of Plastics Engineers
Introduction: Antibiotic-loaded bone cements of poly(methyl methacrylate) are considered as very useful biomaterials for the management of corporal deep osseous infections. However, the high prevalence of resistant germs and polymicrobial infections makes it necessary to search for new formulations of bone cements containing antibiotics for local antibacterial therapy. In this work, bone cements loaded with drugs with different mechanism of action were evaluated to determine its antibacterial effectiveness on Pseudomonas aeruginosa. Methodology: Poly(methyl methacrylate) cements loaded with 10 wt.% of Oleozon®, mixtures of Ciprofloxacin/Meropenem and Ciprofloxacin/Meropenem/Oleozon® were prepared. The in vitro drugs release in water was followed by UV-Vis spectroscopy, and their antibacterial activity against Pseudomonas aeruginosa was evaluated for 11 days using the microdilution method. Results: All the extracts demonstrated an inhibitory effect on the growth of the strain during the whole trial period. Extracts from cement with Oleozon® only presented a total antibacterial inhibitory effect during 20 hours for the extracts taken at day 1 while the extracts from the cements loaded with mixtures of Ciprofloxacin/Meropenem and Ciprofloxacin/Meropenem/Oleozon® showed complete inhibition of the growth of the microorganism, even at 11 days. At the end of the trial period, some of the drugs remained inside the matrices, indicating that they can be released for a longer time in treatments. Conclusions: The results indicated a positive antibacterial effect by the combined used of the two or the three drugs tested against the Gram-negative bacilli Pseudomonas aeruginosa, so these proposal may be a valid alternative to be considered by surgeons.
En este trabajo se presentan los resultados de las investigaciones llevadas a cabo para evaluar el comportamiento de un material híbrido orgánico-inorgánico (HOI) como recubrimiento protector de distintos materiales de construcción. La caracterización mineralógica, estructural y textural de los materiales de construcción estudiados (granito, mármol y arenisca) se llevó a cabo mediante las técnicas: difracción de rayos X (DRX), microscopía electrónica de barrido (MEB), reflectancia total atenuada (ATR) y porosimetría de mercurio. Por otro lado, la caracterización del recubrimiento antivandálico se llevó a cabo mediante ATR y MEB, evaluando su capacidad protectora contra pinturas realizadas por aerógrafo o rotulador, según la mayor o menor facilidad con que se elimina la pintura por limpieza con gamuza. La estabilidad del recubrimiento en el material inorgánico se estudió mediante ensayos acelerados de resistencia a la lluvia y, en el caso del mármol, a la radiación UV. La variación del color experimentada por la superficie después de ser recubierta se estudió, en todos los casos, por colorimetría. Palabras clave: antivandálico, híbrido, recubrimiento, envejecimiento. Surface protection treatments of building materials by new organic-inorganic hybrid multifuncional materialsThe behavior of an organic-inorganic hybrid material (HOI) as protective coating of different building materials has been evaluated in this work. The mineralogical, structural and textural characterization of the inorganic building materials (granite, marble and sandstone) was carried out by: x-ray diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflectance (ATR) and mercury porosimetry. On the other hand, the protective coating was characterized by ATR and SEM, evaluating its protective capacity against paintings made by aerograph or labeller, according to the greater or smaller facility whereupon eliminates the painting by means of cleaning with a cloth. The stability of the coating on the inorganic materials was studied by accelerated tests of rain and UV radiation. Color variation after coating was studied, in all the cases, by colorimetry.
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