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de Azevedo M.B.,Brazilian Nuclear Energy Research Institute (IPEN)
International journal of nanomedicine | Year: 2011

Captopril (CAP) was the first angiotensin I-converting enzyme (ACE) inhibitor to be developed and is widely used in hypertension treatment. On the other hand, cyclodextrins (CDs) are cyclic oligosaccharides whose cone-shaped cavity allows formation of noncovalent inclusion complexes with appropriately sized guest molecules, thus modifying guest physical, chemical, and biological properties. Herein, the physicochemical characterization and in vivo ACE inhibition evaluation of seven CAP/CD complexes are reported. The inclusion complexes were prepared by spray-drying, freeze-drying, kneading, or lyophilization methods and characterized by nuclear magnetic resonance, Fourier-transformed infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and scanning electron microscopy techniques. In vivo assays compared CAP and CAP/CD complex administration (0.5 mg kg(-1) or 0.09 mg kg(-1), n = 4-7) to evaluate the ACE inhibition by continuous infusion of angiotensin I (30 ng 50 μL(-1) min(-1)) in conscious Wistar rats. The physicochemical analysis demonstrated complete amorphization and complexation between CAP and CDs, indicating the substitution of water molecules inside the CD cavity with CAP. During the infusion of angiotensin I, the administration of all CAP/CD complexes induced a reduction in mean arterial pressure similar to that observed upon CAP administration. The nanoparticles obtained by the kneading method (CAP/α-CD:KM) showed a potent and long-lasting inhibitory activity (∼22 hours) on the angiotensin I pressor effect. The results suggest that the inclusion complex of CAP and α-CD can function as a novel antihypertensive formulation that may improve therapeutic use of CAP by reducing its oral dose administration to once per day, thus providing better quality of life for almost 25% of the world's population who suffer from hypertension. Source


Wetter N.U.,Brazilian Nuclear Energy Research Institute (IPEN) | Deana A.M.,Nove de Julho University
Laser Physics Letters | Year: 2013

We present a Nd:YLiF4 diode-side-pumped resonator architecture based on a gain-guided, mode-selective technique that employs a double pass of the fundamental laser mode through the crystal. The folded cavity is very compact, robust and cost efficient. With this design we demonstrate 19 W of quasi-cw, stable diffraction-limited laser emission at 1053 nm when pumping at 792 nm with 35.4 W. The slope efficiency of the laser is 65.3% and the optical-to-optical efficiency is 53.6%, which is, to the best of our knowledge, the highest efficiency reported for Nd:YLiF4 lasers pumped into the 4F5/2 band, including longitudinal pumping schemes and lasers emitting at the higher gain line of 1047 nm. © 2013 Astro Ltd. Source


Wetter N.U.,Brazilian Nuclear Energy Research Institute (IPEN) | Deana A.M.,Nove de Julho University
Applied Physics B: Lasers and Optics | Year: 2014

This work demonstrates the power scalability of double-beam-mode controlling, a technique that has generated the highest optical efficiency reported so far for Nd:YLF lasers. We analyze two types of power scaling possibilities by numerical simulations: multiplication of intracavity pump modules and MOPA configuration. About 44 W of TEM00 output power at 1053 nm was experimentally demonstrated with a beam-parameter product of 1.07 × 1.15. The results show great ease of power scaling without sacrificing beam quality. © 2014, Springer-Verlag Berlin Heidelberg. Source


Wetter N.U.,Brazilian Nuclear Energy Research Institute (IPEN) | Deana A.M.,Nove de Julho University
Optics Express | Year: 2015

We analyze the performance of a VBG equipped diode of narrow linewidth in a side-pumped double-beam, mode-controlled resonator and demonstrate power scaling without loss of beam quality by a factor of three, when compared to previous results. 69 W of diffraction-limited laser output power at 1053 nm in a Nd:YLF lasers are demonstrated with slope efficiency of 65% and record optical-to-optical efficiency of 60%. ©2015 Optical Society of America. Source


Pieretti E.F.,Brazilian Nuclear Energy Research Institute (IPEN) | Costa I.,Brazilian Nuclear Energy Research Institute (IPEN)
Electrochimica Acta | Year: 2013

The surfaces of implantable medical devices should present proper corrosion and mechanical resistance properties to fulfil their functions. Marking techniques are used for identification and traceability purposes but often generate surface modifications. Because surface defects affect corrosion resistance, the effects of marking processes must be investigated. This paper presents the effects of pulsed Nd:YAG laser marking techniques on the corrosion resistance of ASTM F139 austenitic stainless steel compared to that of mechanical marking techniques. The corrosion resistance was evaluated by electrochemical methods, and the surface was analysed by scanning electron microscopy with a field emission gun (SEM-FEG) coupled to an energy dispersive X-ray spectrometer. The surface characterisation showed the occurrence of microstructure variation due to the high temperatures involved in the laser melting process. Compared to the mechanical method, the laser marking technique had a deleterious effect on the resistance of ASTM F139 stainless steel to localised corrosion, increasing its susceptibility to pitting corrosion. These results were related to changes in the passive film properties, surface morphology and chemical composition. © 2013 Elsevier Ltd. Source

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