Systematic evaluation of a holmium:yttrium-aluminum-garnet laser lithotripsy device with variable pulse peak power and pulse duration

AbstractObjectiveThe Holmium:yttrium-aluminum-garnet (Ho:YAG) laser is the standard lithotrite for ureteroscopy. This paper is to evaluate a Ho:YAG laser with a novel effect function in vitro, which allows a real-time variation of pulse duration and pulse peak power.MethodsTwo types of phantom calculi with four degrees of hardness were made for fragmentation and retropulsion experiments. Fragmentation was analysed at 5 (0.5 J/10 Hz), 10 (1 J/10 Hz), and 20 (2 J/10 Hz) W in non-floating phantom calculi, retropulsion in an ureteral model at 10 (1 J/10 Hz) and 20 (2 J/10 Hz) W using floating phantom calculi. The effect function was set to 25%, 50%, 75%, and 100% of the maximum possible effect function at each power setting. Primary outcomes: fragmentation (mm3), the distance of retropulsion (cm); ≥5 measurements for each trial.ResultsAn increase of the effect feature (25% vs. 100%), i.e., an increase of pulse peak power and decrease of pulse duration, improved Ho:YAG laser fragmentation. This effect was remarkable in soft stone composition, while there was a trend for improved fragmentation with an increase of the effect feature in hard stone composition. Retropulsion increased with increasing effect function, independently of stone composition. The major limitations of the study are the use of artificial stones and the in vitro setup.ConclusionChanges in pulse duration and pulse peak power may lead to improved stone fragmentation, most prominently in soft stones, but also lead to increased retropulsion. This new effect function may enhance Ho:YAG laser fragmentation when maximum power output is limited or retropulsion is excluded

Primer registro basado en código de barras de ADN de Lysiosquilla maculata (Crustacea: Stomatopoda) de la costa de Chennai, Tamil Nadu, India

The taxonomic identification of mantis shrimp Lysiosquilla maculata was performed through DNA barcoding analysis of specimens collected from the Kasimedu fishing port, Chennai coast, Tamil Nadu, India. The mitochondrial cytochrome oxidase subunit I (mtCOI) gene with a region of 650 bp was sequenced for phylogenetic analysis. In the present record, mitochondrial gene sequences were used to identify the mantis shrimp. This is the first confirmed DNA barcoding record from Indian waters, whose mtCOI sequence was deposited in GenBank. The Neighbor-joining method was used for phylogenetic analysis. The calculated pairwise genetic distance with five closely related species ranged from 0.01 to 0.094%. The morphological and molecular analysis confirm that the specimens collected correspond to L. maculata.La identificación taxonómica del camarón mantis Lysiosquilla maculata se realizó mediante análisis de códigos de barras de ADN de especímenes recolectados en el puerto pesquero de Kasimedu, costa de Chennai, Tamil Nadu, India. Se secuenció el gen de la subunidad I de la citocromo oxidasa mitocondrial (mtCOI) con una región de 650 pb para análisis filogenético. En el presente registro, se utilizaron secuencias de genes mitocondriales para identificar el camarón mantis. Este es el primer registro confirmado de códigos de barras de ADN en aguas indias, cuya secuencia de mtCOI se depositó en el GenBank. Se utilizó el método Neighbor-joining para el análisis filogenético. La distancia genética por pares calculada con cinco especies estrechamente relacionadas osciló entre 0,01 y 0,094%. Los análisis morfológicos y moleculares confirman que los ejemplares colectados corresponden a L. maculata

Degradaçao de benzeno, tolueno e xilenos (BTX) via processos oxidativos avançados

Orientador: Patricio Guillermo Peralta ZamoraDissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Ciencias Exatas, Programa de Pós-Graduaçao em Química. Defesa: Curitiba, 2004Inclui bibliografiaÁrea de concentraçao: Química analíticaResumo: O aumento da população e o conseqüente crescimento da atividade industrial podem ser apontados como fatores decisivos na manifestação do fenômeno de contaminação ambiental, principalmente em função da geração de inúmeros poluentes químicos. Dentre outros importantes agentes contaminantes, destaque especial pode ser dado aos hidrocarbonetos constituintes da gasolina e outros derivados do petróleo, principalmente benzeno, tolueno e xilenos, em razão da freqüência com que eventos de contaminação acontecem, da marcada toxicidade e cardnogenicidade de alguns hidrocarbonetos e da relativa freqüência com que estas espécies são encontradas em águas subterrâneas, aqüíferos e mananciais. Em geral, observa-se que os processos de bioremediação e bioatenuação natural apresentam a melhor viabilidade econômica para aplicação em rotinas de remediação de sítios contaminados. Entretanto, grande parte destas alternativas, mostram-se extremamente demoradas e especialmente ineficientes frente ao benzeno. Em função destes fatos, a busca de novas alternativas para a remediação de águas contaminadas mostra-se absolutamente essencial. No presente trabalho avaliou-se a potencialidade de alguns processos oxidativos avançados, a saber fotocatálise heterogênea (T1O2/UV), peroxidação assistida por radiação ultravioleta (UV/H2O2) e sistemas Fenton e fòto-Fenton, em relação à degradação de soluções aquosas contendo benzeno, tolueno e xilenos (BTXs). Posteriormente, o processo de melhor desempenho (sistema foto-Fenton- Vis) foi utilizado em estudos de remediação envolvendo soluções aquosas contaminadas por gasolina, amostras estas produzidas em laboratório. Os resultados indicam que os sistemas TÍO2/UV e UV// H2O2 permitem uma completa degradação dos substratos de interesse, em tempos de reação inferiores a 20 min. Intermediários fenólicos são gerados em ambos casos, grande parte dos quais pode ser removida estendendo-se o tratamento por tempos de 60 e 30 min, respectivamente. Na sua forma assistida por radiação ultravioleta, o processo Fenton apresentou uma eficiência significativamente maior, representada por uma completa degradação das espécies em estudo e dos intermediários de reação, em tempos de reação da ordem de 15 minutos. Entretanto, especial destaque merece ser dado ao sistema fòto-Fenton assistido por radiação solar, que possibilitou a degradação dos BTXs e dos seus intermediários fenólicos em tempos de reação de 30 min. Os estudos orientados à obtenção de amostras aquosas contaminadas com os constituintes presentes na gasolina revelaram que o contato de 24 horas, em repouso, permite a solubilização de BTXs em concentração da ordem de 5 mg L-1. O posterior estudo de degradação, através do sistema foto-Fenton-Vis, demonstrou que 15 minutos de tratamento são suficientes pana promover a degradação dos BTXs presentes na solução aquosa.Abstract: The enhancement of the world's population and the consequent exacerbation of the industrial activity can be appointed as crucial facts on the environmental pollution phenomenon, mainly due to generation of many pollutants of diverse chemical nature. Besides a great number of well-know contaminating agents special attention has been done to the hydrocarbons that derived from gasoline and other crude oil derivates, chiefly benzene, toluene and mixed xylenes (BTX). In view of the high frequency of contamination events, the known toxicity and carcinogenic character of some hydrocarbons and its frequently occurrence in underground waters, the development of adequate remediation routines is absolutely essential. In general, bioremediation and natural attenuation processes has presented the best economic viability for remediation of contaminated sites. However, most of these alternatives are very lengthy and clearly inefficient toward degradation of benzene. In this work the potentiality of some advanced oxidation processes, such as heterogeneous photocatalysis (Ti02/UV), peroxidation assisted by UV-light (UV/ H2O2), Fenton and photo-Fenton processes, has been evaluated toward the degradation of aqueous samples containing benzene, toluene and xylenes (BTX). In addition, the most effective process (photo-Fenton-Vis) was used in remediation studies involving artificially produced gasoline-contaminated aqueous solutions. The results indicated that T1O2AJV and UV/H2O2 systems allow the complete degradation of the studied substrates at reaction times lower than 20 min. In both cases phenolic intermediates are generated, transient species that are removed by prolonging the treatment up to 60 and 30 min, respectively. When assisted by UV irradiation the Fenton process manifeste a better efficiency, represented by a complete degradation of BTXs and transient species at reaction times of about 15 minutes. Especially remarkable were the results observed in the solar-light assisted photo-Fenton system, represented by complete degradation of BTXs and almost total removal of phenolic intermediates at reaction times of 30 min. Aqueous samples containing organics compounds present in gasoline were prepared by contacting commercial gasoline and water. At contacting times of 24 hours the solubilization of hydrocarbons is very significant, permitting BTX concentrations of about 5 mg L-1. The later degradation study by the photo-Fenton- Vis process showed that 15 minutes of treatment are enough to promotes the degradation of the BTXs presents in the aqueous solution

Assessment of UV-Vis LED-assisted Photo-Fenton Reactor for Atrazine Degradation in Aqueous Solution

Atrazine is one of the most used pesticides, although it is extremely toxic for living organisms. In spite of that, the control, removal, and elimination of this agrochemical are still deficient in water treatment plants (just over 25%). For this reason, the main objective of this study was to evaluate atrazine degradation efficiency in aqueous solution using the photo-Fenton system assisted by a light-emitting diode (LED) lamp. The degradation results of 30 mg L-1 atrazine evidenced that our approach presented an efficiency of approximately 98% in only 240 minutes of reaction, and the observed mineralization was 60% of total organic carbon (TOC). Several byproducts were identified (such as HA, DEA, DIA, HDEA, HDIA, and HDEDIA), and the degradation mechanism followed dechlorination and hydroxylation pathways that produce HDEDIA or ammelide. In this way, the photo-Fenton system under an LED lamp showed to be highly efficient at removing atrazine from aqueous solutions, offering several advantages compared to the traditional system, such as lower energy consumption and more environmentally friendly features. DOI: http://dx.doi.org/10.17807/orbital.v13i2.153

Photo-Fenton Process Using Fe(III) Ions from Modified Sugarcane Bagasse for Reactive Black 5 Dye (RB5) Removal

Brazil is one of the largest generators the sugarcane bagasse, this kind of biomass has already shown efficiency related to its in natura adsorption potential (when physically or chemically activated), it can also be used to remove contaminants from water in methods such as advanced oxidative processes. In this study, chemical modifications were carried out in sugarcane bagasse to enable its application in photo-Fenton processes for the degradation of reactive black 5 dye. The materials were chemically activated through immersion in Fe(III) solution for different periods of time: 3, 6, 9, 12, 24, 48 and 96 h; and were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), zeta potential analysis, internal surface area and leached metal quantification. The results showed the cellulose structure, which is predominant in the sugarcane bagasse it was not considerably modified after activation with FeCl3 and evidence of the presence of Fe(III) ions on the surface of the studied material. The degradation efficiency (after 5 min and using 11.5 mg L-1 hydrogen peroxide) for the activated materials was respectively: 55.85%, 49.44%, 71.22%, 92.87%, 88.16% and 98.02%, considering the decrease of the band related to the chromophore group (598 nm). DOI: http://dx.doi.org/10.17807/orbital.v13i2.148

Observation of whale shark Rhincodon typus Smith, 1828 in oceanic waters of the Bay of Bengal, India

The present study was based on sighting of whale shark, Rhincodon typus Smith, 1828 on 13th and 14th October 2016 incidentally in oceanic waters of Bay of Bengal at a depth of 3340 and 3270 m. These two sightings were thus confirmed by photographs. Whale sharks were reported in the coastal and near shore regions of India by many of the researchers and this is the first observation of R. typus in oceanic waters of east coast of India

Effect of pH Variation on Synthesis and Photocatalytic Activity of Bi2Fe4O9

The Pechini synthesis method, presents chemical homogeneity as its main advantage, enabling the desired phase to be obtained. This synthesis usually occurs at pH 7. In this study, Bi2Fe4O9 was synthesized using the Pechini method at different pHs (pH= 3, 5, 7, 8, 10 and 12) to verify if the pH conditions can influence in its photocatalytic activity. The materials obtained at different conditions were characterized by using X rays diffraction (XRD), UV/Vis diffuse reflectance and scanning electron microscopy by field emission (MEV/FEG).It was possible to synthesize the material under conditions already mentioned, but it was not observed significant differences in the chemical structure of the obtained materials from the characterization techniques. However, they presented a small variation in the band gap values, morphological aspects and photocatalytic activities. All the materials proved to be a good semiconductor, maintaining high degradation rates. The photocatalyst synthesized at pH 3 (BFO - 1) presented a degradation rate of approximately 95% for the group chromophore and 93% for the aromatic group of the structure of the tartrazine yellow dye, proving to be a promising photocatalyst for industrial applications. This result is particularly important because BFO – 1 showed higher catalyst activity since the chromophore of the aromatic group was degraded. The highlights of this study is the synthesis of Bi2Fe4O9 performed at pH=3, since it reduces the quantity of reagents comparing to the conventional Pechini method and presented high photocatalytic activity. DOI: http://dx.doi.org/10.17807/orbital.v13i2.148