Showing papers by "National Nuclear Energy Commission published in 2007"

Antimicrobial Photodynamic Therapy Combined With Conventional Endodontic Treatment to Eliminate Root Canal Biofilm Infection

Abstract: Background and Objective: To compare the effectiveness of antimicrobial photodynamic therapy (PDT), standard endodontic treatment and the combined treatment to eliminate bacterial biofilms present in infected root canals. Study Design/Materials and Methods: Ten singlerooted freshly extracted human teeth wereinoculated with stable bioluminescent Gram-negative bacteria, Proteus mirabilis and Pseudomonas aeruginosa to form 3-day biofilms in prepared root canals. Bioluminescence imaging was used to serially quantify bacterial burdens. PDT employed a conjugate between polyethylenimine and chlorin(e6) as the photosensitizer (PS) and 660-nm diode laserlightdeliveredintotherootcanalviaa200-mfiber,and thiswascomparedandcombinedwithstandardendodontic treatment using mechanical debridement and antiseptic irrigation. Results: Endodontic therapy alone reduced bacterial bioluminescence by 90% while PDT alone reduced bioluminescence by 95%. The combination reduced bioluminescence by >98%, and importantly the bacterial regrowth observed 24 hours after treatment was much less for the combination (P<0.0005) than for either single treatment. Conclusions:Bioluminescenceimagingisanefficientway tomonitorendodontictherapy.AntimicrobialPDTmayhave aroletoplayinoptimizedendodontictherapy. LasersSurg. Med. 39:59‐66, 2007. ! 2006 Wiley-Liss, Inc.

Electrochemical evaluation of Ti-13Nb-13Zr, Ti-6Al-4V and Ti-6Al-7Nb alloys for biomedical application by long-term immersion tests

Abstract: In this investigation the electrochemical behaviour of the Ti-13Nb-13Zr, Ti-6A1-4V and Ti-6A1-7Nb alloys, for application as implant materials was evaluated in Hanks' solution by electrochemical techniques. The alloys were immersed in this solution for 410 days and periodically they were tested by electrochemical impedance spectroscopy. At the end of this period, polarization curves of the three titanium alloys were obtained. The electrochemical impedance experimental results were interpreted using an equivalent electrical circuit that simulates a duplex structure oxide composed of an inner compact layer, here called barrier layer, and an outer and porous layer. The results indicated that all the alloys present a very high corrosion resistance in the electrolyte used, typical of passive alloys, and that the corrosion resistance is mainly due to the barrier layer. The passive like behaviour was maintained during the whole period of test.

Bactericidal effect of malachite green and red laser on Actinobacillus actinomycetemcomitans

Abstract: The aim of this study was to investigate the ability of malachite green (MG) combined with a low-power red laser to kill Actinobacillus actinomycetemcomitans and to investigate MG photodegradation after photodynamic therapy (PDT) by optical absorption spectroscopy. The etiology of periodontal disease is that microorganisms form a bacterial biofilm on the surface of the teeth. It is an infectious disease and A. actinomycetemcomitans is considered an important agent in biofilm ecology. Instead of using antibiotics, PDT is an alternative approach to eradicate bacteria. Cultures of A. actinomycetemcomitans were exposed to a 30 mW diode red laser, in the presence or absence of MG. A group of cultures was treated in dark conditions in the presence of MG (0.01% w/v) for 5 min. In the presence of MG, two exposure times for laser irradiation were used: t = 3 min (energy dose = 5.4 J/cm2), and t = 5 min (energy dose = 9 J/cm2). The samples were diluted and bacterial colonies were counted and converted into colony forming units. Absorption spectra of the bacterial suspensions, MG, MG-stained bacterial suspensions, and photosensitized bacterial suspensions were obtained. A. actinomycetemcomitans can be photoinactivated by a red laser in the presence of MG. Significant differences were observed between the two energy doses used (p

Polymer Solar Cells Using Single-Wall Carbon Nanotubes Modified with Thiophene Pedant Groups

Abstract: Single-wall carbon nanotubes (SWCNT) have attracted great interest for applications in a variety of research areas, including electronics and functional materials. However, a good dispersion of these materials in polymer matrices is a demanding factor in order to obtain more homogeneous and less bundled films for constructing optoelectronic and electrochemical devices. In this report we describe a covalent modification with thiophene groups located at the edges and at defects in SWCNT to modify the interaction with the polymer matrix aiming at its application in solar cells. The modified SWCNT and its composites with poly(3-octylthiophene) were characterized by Raman, infrared, UV−vis, and luminescence spectroscopies and cyclic voltammetry. The best bulk heterojunction solar cell was obtained using 5 wt % of the modified carbon nanotube (SWCNT-THIOP) and shows open circuit voltage (VOC), short-circuit current (Isc), and efficiency (η) of 0.75 V, 9.5 μA cm-2, 0.184%, respectively.

Effects of a single near-infrared laser treatment on cutaneous wound healing: biometrical and histological study in rats.

Abstract: Background Low intensity laser therapy has been recommended to support the cutaneous repair; however, so far studies do not have evaluated the tissue response following a single laser treatment. This study investigated the effect of a single laser irradiation on the healing of full-thickness skin lesions in rats. Methods Forty-eight male rats were randomly divided into three groups. One surgical lesion was created on the back of rats using a punch of 8 mm in diameter. One group was not submitted to any treatment after surgery and it was used as control. Two energy doses from an 830-nm near-infrared diode laser were used immediately post-wounding: 1.3 J cm−2 and 3 J cm−2. The laser intensity 53 mW cm−2 was kept for both groups. Biometrical and histological analyses were accomplished at days 3, 7 and 14 post-wounding. Results Irradiated lesions presented a more advanced healing process than control group. The dose of 1.3 J cm−2 leaded to better results. Lesions of the group irradiated with 1.3 J cm−2 presented faster lesion contraction showing quicker re-epithelization and reformed connective tissue with more organized collagen fibers. Conclusions Low-intensity laser therapy may accelerate cutaneous wound healing in a rat model even if a single laser treatment is performed. This finding might broaden current treatment regimens.

Reference Material for Radionuclides in Sediment, IAEA-384 (Fangataufa Lagoon Sediment)

Abstract: A reference material designed for the determination of anthropogenic and natural radionuclides in sediment, IAEA-384 (Fangataufa Lagoon sediment), is described and the results of certification are presented. The material has been certified for 8 radionuclides (40K, 60Co, 155Eu, 230Th, 238U, 238Pu, 239+240Pu and 241Am). Information values are given for 12 radionuclides (90Sr, 137Cs, 210Pb (210Po), 226Ra, 228Ra, 232Th, 234U, 235U, 239Pu, 240Pu and 241Pu). Less reported radionuclides include 228Th, 236U, 239Np and 242Pu. The reference material may be used for quality management of radioanalytical laboratories engaged in the analysis of radionuclides in the environment, as well as for the development and validation of analytical methods and for training purposes. The material is available from IAEA in 100 g units.

Saccharomyces cerevisiae strain 905 reduces the translocation of Salmonella enterica serotype typhimurium and stimulates the immune system in gnotobiotic and conventional mice

Abstract: Previous results in the laboratory of the authors showed that Saccharomyces cerevisiae strain 905, isolated during ‘cachaca’ production, was able to colonize and survive in the gastrointestinal tract of germ-free and conventional mice, and to protect these animals against oral challenge with Salmonella enterica serotype Typhimurium or Clostridium difficile. In the present work, the effects of S. cerevisiae 905 on the translocation of Salm. Typhimurium (mesenteric lymph nodes, Peyer's patches, spleen, liver) as well as on the immune system (number of Kupffer cells, immunoglobulin production, clearance of Escherichia coli B41) were evaluated in gnotobiotic and/or conventional mice. The treatment with the yeast reduced significantly the translocation of Salm. Typhimurium to liver in gnotobiotic animals and to all the organs tested in conventional mice. The number of Kupffer cells per 100 hepatocytes in liver was significantly higher (P<0.05) in yeast mono-associated mice (52.9±15.7) than in germ-free controls (38.1±9.0). Probably as a consequence, clearance of E. coli B41 from the bloodstream was more efficient in yeast mono-associated animals when compared to germ-free mice. Higher levels (P<0.05) of secretory IgA in intestinal content and of IgA and IgM in serum were observed in yeast mono-associated mice when compared to germ-free group. Concluding, the protection against pathogenic bacteria observed in a previous study was probably due to a modulation of both local and systemic immunity of mice treated with S. cerevisiae 905.

Ultrastructural and autoradiographical analysis show a faster skin repair in He-Ne laser-treated wounds.

Abstract: There are evidences that low-intensity red laser radiation is capable to accelerate wound healing. Nowadays, this therapy has been gradually introduced in clinical practice although mechanisms underlying laser effects are poorly understood. To better understand the photobiological effects of laser radiation, this study investigated by electron microscopy, immunohistochemistry and autoradiography the morphological and functional features of irradiated and none irradiated injured mice skin. Full-thickness skin lesions were created on the back of mice and irradiated on days 1, 5, 8, 12, and 15 post-wounding with a He-Ne laser (lambda=632.8nm), dose 1J/cm(2), exposure time 3min. Non-irradiated lesions were used as a control. The mice were inoculated with (3)H-proline and sacrificed one hour after on the 8th, 15th and 22nd days to histological and radioautographical analysis. The irradiated-lesions showed a faster reepithelization compared with control lesions. The irradiated dermis contained a higher number of activated fibroblasts compared to control group and, most of them showed several cytoplasmic collagen-containing phagosomes. In irradiated-lesions, smooth muscle alpha-actin positive cells predominated, which correspond to a higher number of myofibroblasts observed in the electron microscope. Moreover, laser radiation reduced the local inflammation and appears to influence the organization of collagen fibrils in the repairing areas. Quantitative autoradiography showed that the incorporation of (3)H-proline was significantly higher in irradiated-dermis on the 15th day post-wounding (p<0.05). These results suggest that laser radiation may accelerate cutaneous wound healing in a murine model.

Pd–heteropoly acid as a bifunctional heterogeneous catalyst for one-pot conversion of citronellal to menthol

Abstract: Pd–H3PW12O40/SiO2 catalyzes the one-pot transformation of (+)-citronellal to menthol via acid-catalyzed cyclization followed by Pd-catalyzed hydrogenation, with 92% yield of menthol at 100% citronellal conversion and 85% stereoselectivity for the desired (−)-menthol.

Nafion-Titanate Nanotube Composite Membranes for PEMFC Operating at High Temperature

Abstract: Nafion-titanate nanotube composites were investigated as electrolytes for proton exchange membrane fuel cells (PEMFCs) operating at high temperature T. With the addition of 5-15 wt % of nanotubes to the ionomer, PEMFC performance can be significantly sustained for T up to 130°C. The polarization curves of PEMFCs using the composite electrolytes reflect a competing effect between an increase in water uptake due to the extremely large surface area of the nanotubes and a decrease in proton conductivity of the composites.

Carbon nanotube–polybithiophene photovoltaic devices with high open‐circuit voltage

Abstract: We report the preparation of photovoltaic devices using modified single wall carbon nanotubes, SWNTs. Devices are produced stacking on top of fluorine-doped tin-oxide, an electrochemically deposited polybithiophene layer, a layer of SWNT blended with poly(3-octylthiophene) and an evaporated top metal contact, Ca/Al or Al. Ca/Al-top-electrode devices achieve open-circuit voltages of 1.81 V and average power conversion efficiency of 1.48% at irradiance of 15.5 W m–2, spectrally distributed following AM1.5. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Thermal analysis of teeth irradiated with Er,Cr:YSGG at low fluences

Abstract: This study aimed to evaluate the surface and pulp temperature rises when teeth are irradiated with Er,Cr:YSGG laser at low fluences, with or without a photosensitizer. It was chosen 81 third molar human teeth which were randomly divided into six groups, according to the Er,Cr:YSGG laser fluences (2.8 J/cm2, 5.6 J/cm2, and 8.5 J/cm2) and the recovering or not of a photosensitizer (a thin layer of coal paste) over enamel surfaces. All samples were irradiated without coolant. The surface temperatures and heat propagation were recorded by thermographic camera, and the pulpal temperatures were registered by type-K thermocouples. After laser irradiation, enamel surfaces were analyzed by scanning electron microscopy (SEM). The intrapulpal temperature increases were below the threshold for pulp damages (5.6°C), and they were dependent on the fluence applied. The surface recovering with coal paste significantly reduced the intrapulpal temperature increments in 8.5 J/cm2 samples. The coal paste also influenced the surface temperatures, which reached 222.6°C when samples were irradiated at fluence of 8.5 J/cm2. The SEM analysis revealed a micro-ablation pattern for all fluences tested. The photosensitizer was efficient for reducing heat transfer to the pulp chamber, increasing laser absorption into the enamel. The fluences of 8.5 J/cm2 was able to achieve surface temperature rises that suggest crystallographic changes on enamel, which could propitiate an increase of acid-resistance of enamel.

Chemical characterization and recent sedimentation rates in sediment cores from Rio Grande reservoir, SP, Brazil

Abstract: The Rio Grande reservoir lies southeast of the Metropolitan Area of Sao Paulo. In order to evaluate if the sediments contain a historical registration of anthropogenic activity, four sediment cores were sampled from the reservoir. In these cores the Hg concentration was determined by the CV AAS technique, major and trace elements by instrumental neutron activation analysis and the sedimentation rates by the 210Pb method. The results obtained for Hg are much higher than expected, showing an anthropogenic contribution. As a general trend, the elemental concentration decreases with depth, indicating recent contamination.

Characterization of natural carious lesions by fluorescence spectroscopy at 405-nm excitation wavelength

Abstract: We aim to characterize natural caries enamel lesions by fluorescence spectroscopy. Sixty human samples with natural non- cavitated caries lesions on smooth surfaces were selected and classi- fied into three groups: dull, shiny, and brown lesions. All the samples were analyzed externally at the natural surface and after hemisec- tionig internally at the center of the lesion. The lesions were excited with a 405-nm InGaN diode laser and the fluorescence was collected with a single grating spectrometer. Four emission bands 455, 500, 582, and 622 nm are identified in both sound and carious regions. The area under each emission band is correlated with the total area of the four bands for the sound and carious regions. The detected fluo- rescence from natural and cut surfaces through the caries lesions is not statistically different for the shiny and dull lesion, but is different analysis of variance ANOVA p0.05 for brown lesion at all emission bands. At the 405-nm excitation wavelength, the area of the fluorescence bands at 455 and 500 nm differ statistically for natural carious lesions and sound tissue. © 2007 Society of Photo-Optical Instrumentation

Study of blood porphyrin spectral profile for diagnosis of tumor progression.

Abstract: Renal cell carcinoma (RCC) accounts for approximately 3% of new cancer incidence and mortality in the United States. Unfortunately many RCC masses remain asymptomatic and nonpalpable until they are advanced. Diagnosis and localization of early carcinoma play an important role in the prevention and curative treatment of RCC. The autofluorescence of blood porphyrin of healthy and tumor induced in male SCID mice was analyzed using fluorescence and excitation spectroscopy. A significant contrast between normal and tumor blood could be established. Blood porphyrin fluorophore showed enhanced fluorescence band (around 630 nm) in function of the tumor growth. This indicates that either the autofluorescence intensity of the blood fluorescence may provide a good parameter for the “first approximation” characterization of the tumor stage.

Endostatin expression in the murine model of ischaemia/reperfusion-induced acute renal failure.

Abstract: SUMMARY: Background: Renal ischaemia-hypoxia is a leading cause of acute renal failure, a clinical condition associated with rapid loss of renal function and high rates of mortality. Renal proximal tubular cells are the most severely injured during renal ischaemia, caused by the breakdown of the extracellular matrix of the tubular basement membrane. Endostatin is the C-terminal fragment of collagen XVIII generated by proteolytic cleavage and it is well-known as being an inhibitor of angiogenesis. In vitro, endostatin inhibits endothelial cell proliferation and migration, as well as tubule formation. In vivo, it has a potent inhibitory effect on tumour growth. In this study, we analysed endostatin gene expression in C57BL/6 mouse kidneys subjected to ischaemia/reperfusion. Methods: Ischaemic renal failure was induced via 45 min of bilateral occlusion of the renal artery and vein, followed by 12 h or 24 h of reperfusion. Whole-kidney homogenate and total RNA were extracted for examination by western blot analysis and quantitative polymerase chain reaction. The immunohistological examination revealed increased endostatin expression in injured kidney, mainly in the proximal tubule and collecting ducts. Results: Endostatin/collagen XVIII mRNA and protein expression increased during ischaemia and within 12 h of reperfusion. In the western blot assay, we identified increased expression of the 30 kDa endostatin-related fragment and of matrix metalloproteinase-9. CD31 was significantly expressed during reperfusion (P < 0.05). Immunohistological examination revealed glomerular and tubulointerstitial expression of endostatin. Conclusion: These data suggest the local synthesis of a 30 kDa endostatin-related fragment following acute renal failure and suggest its role in the modulation of renal capillary density.

The swelling behavior of chitosan hydrogels membranes obtained by UV- and γ-radiation

Abstract: In order to develop a non toxicity and biocompatible hydrogel system with potential ability in biotechnology based on membranes of polyethylene glycol (PEG 300 and 400) and chitosan were prepared under ultraviolet light (UV) and γ-radiation curing, at room temperature. The hydrogels were characterized by FTIR spectroscopic, UV absorption spectroscopy, thermal analysis and scanning electronic microscopy. The swelling behaviors were investigated in terms of time of swelling, irradiation time, and pH. The hydrogel with PEG 300 showed unusual swelling behavior.