SYNTHESIS OF MESOPOROUS OF NyTi1-xCexO2-y STRUCTURES AND ITS VISIBLE LIGHT INDUCED PHOTOCATALYTIC PERFORMANCE

R. RANGEL,J. D. GARCÍA-ESPINOZA,I. ESPITIA,P. QUINTANA,P. BARTOLO-PÉREZ,J. J. ALVARADO-GIL,R. TREJO-TZAB 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.5

The present work was addressed to study the visible light induced performance as photocatalysts of mesoporous NyTi1–xCexO2–y structures obtained under microwave irradiation. The titanium dioxide (TiO2) was doped with cerium and nitrogen in order to improve the quantum efficiency of the TiO2 and to shift its adsorption spectra to the visible region. The prepared meso-powders were analyzed by means of X-ray diffraction (XRD), scanning Electron microscopy (SEM), infrared (IR) spectroscopy, transmission electronic microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The surface area was evaluated by means of the Brunauer-Emmett-Teller (BET) method and ultraviolet (UV)-visible diffuse reflectance measurements were performed in order to determine the band gap energy. In addition, the photocatalytic activity of the samples was evaluated by monitoring the photodegradation of methylene blue (MB) under UV and visible light energy irradiation. The results show that our methodology is an effective way for incorporating cerium and nitrogen into TiO2 compound, which in turn, increases its photocatalytic activity. The diffuse reflectance analysis confirms that the absorption edge was shifted towards the visible region of the optical spectrum. The XRD diffraction patterns indicate homogeneous solid solutions in which prevails the anatase phase. It was observed a reduction in crystal size from 13.1 nm to 7.7 nm for NyTi0.98Ce0.02O2–y in comparison to TiO2. The textural properties of the synthesized compounds were determined, by means of adsorption isotherms indicating the formation of mesoporous structures. IR spectra show characteristic vibration signals attributed to Ti–O–Ti bonds, as well as vibrations assigned to cerium and nitrogen bonds. The XPS analyses evidence the presence of Ce3+/Ce4+ redox couple and Ti–N bonds. The photocatalityc efficiency was evaluated in the degradation of MB monitoring the absorbance change at 664 nm. The degradation of this compound was 91.4% using NyTi0.98Ce0.02O2–y as photocatalyst under UV energy in 90 min. Also 38.7% of MB degradation was achieved in 150 min under visible light radiation.

Advantages of Hydrothermal Synthesis to Produce Tunable TiO2 Nanomicro Sized Photocatalysts and Their Effect in Lignin Degradation

R. Rangel,J. A. Cortes,J. Lara,P. QUINTANA,J. J. ALVARADO-GIL,O. Contreras 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.3

Studies on photocatalytic degradation of lignin are scarce, even though it is an effective method for treatment of industrial effluents. In the present work, an advanced oxidation process (AOPs), leading to the photodegradation of lignin aqueous solutions, is proposed by using microstructured (T-MT) and nanostructured (T-NT) titanium dioxide compounds. Hydrothermal synthesis, in accordance with an experimental factorial design considering time of synthesis, NaOH concentration and synthesis temperature, was used to produce tunable TiO2 photocatalysts for further study of its effects on the degradation of lignin. Photocatalytic reactions were conducted in a micro reactor batch system under UV irradiation. The catalysts were analyzed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area and porosity analyzer (BET), energy-dispersive X-ray spectroscopy (EDS) and UV-Vis diffuse reflectance spectroscopy. In order to optimize the yield reaction, an experimental factorial design was performed. According to our results, nanostructured TiO2 consisting in different structural features and light absorption properties were produced using this method. It is shown that T-MT and T-NT compounds exhibit a wide range of values, for the kinetic parameters, in photoinduced degradation of methylene blue (MB) and lignin.

The impact of incontinence etiology on artificial urinary sphincter outcomes

Adam R. Miller,Brian J. Linder,Laureano J. Rangel,David Y. Yang,Daniel S. Elliott 대한비뇨의학회 2017 Investigative and Clinical Urology Vol.58 No.4

Purpose: To evaluate the impact of incontinence etiology on artificial urinary sphincter (AUS) device outcomes. Materials and Methods: We identified 925 patients who underwent primary AUS placement from 1983 to 2011. The etiology of incontinence was categorized as radical prostatectomy alone, radical prostatectomy with radiation, benign prostate resection, and those with cryotherapy as a salvage prostate cancer treatment. Hazard regression and competing risk analyses were used to determine the association of the etiology of incontinence with device outcomes. Results: The distribution of the 4 etiologies of incontinence included: 598 patients (64.6%) treated with prostatectomy alone, 206 (22.2%) with prostatectomy and pelvic radiation therapy, 104 (11.2%) with benign prostate resection, and 17 (1.8%) with prior cryotherapy. With a median follow-up of 4.9 years (interquartile range, 1.2–8.8 years), there was significant difference in the cumulative incidence of device infection/urethral erosion events between the four etiologies (p=0.003). On multivariable analysis, prior cryotherapy (reference prostatectomy alone; hazard ratio [HR], 3.44; p=0.01), older age (HR, 1.07; p=0.0009) and history of a transient ischemic attack (HR, 2.57; p=0.04) were associated with an increased risk of device infection or erosion. Notably, pelvic radiation therapy with prostatectomy was not associated with an increased risk of device infection or erosion (reference prostatectomy alone, p=0.30). Conclusions: Compared to prostatectomy alone, prior treatment with salvage cryotherapy for recurrent prostate cancer was associated with an increased risk of AUS infection/erosion, whereas radiation (in addition to prostatectomy) was not.

Topical and Systemic Anti-Inflammatory Effects of Echinodorus macrophyllus (Kunth) Micheli (Alismataceae)

Ellen Tanus-Rangel,Scheila R. Santos,Lousa˜ Lopes,Vaˆnia Noldin,Franco D. Monache,Valdir Cechinel-Filho,Domingos T.O. Martins 한국식품영양과학회 2010 Journal of medicinal food Vol.13 No.5

Echinodorus macrophyllus leaf has been used in Brazilian folk medicine to treat inflammatory conditions and kidney dysfunctions. The present study evaluated the effects of leaf ethanolic extract from E. macrophyllus (EEEm) in acute and subchronic models of inflammation. The EEEm was found to cause significant and potent inhibition of carrageenan- and dextran-induced paw edema in rats and marked decreases in the exudate volume and leukocyte migration in rats with carrageenan-induced pleurisy, the vascular permeability increase induced by intraperitoneal acetic acid, and the croton oil-induced topical ear edema in mice. On the other hand, the EEEm was not active in the test model of cotton pellet-induced granuloma in rats. Phytochemical analysis with E. macrophyllus leaves revealed the presence of triterpenoids, steroids, flavones, flavonols, and xanthones. Two flavonoids were isolated from the ethyl acetate fraction and identified as isovitexin and vitexin. Our results support the traditional use of E. macrophyllus leaves in the treatment of acute inflammatory conditions

Preparation and characterization of polymer/layered silicate pharmaceutical nanobiomaterials using high clay load exfoliation processes

Jaqueline Correia Villac¸a,Luiz Cla´udio R. Pereira da Silva,Luisa Helena Falca˜o Barbosa,Carlos Rangel Rodrigues,Luiz Marcelo Lira,Fla´ via Almada do Carmo,Valeria Pereira de Sousa,Maria Ineˆs Bruno 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6

The purpose of this study was to prepare and characterize lamellar silicate nanocomposites usingexfoliation processes, high clay load and polyvinylpyrrolidone (PVP), ethylcellulose (EC) andpolyquaternium-H (PQH). The clays (sodium montmorillonite, Viscogel S4TM, S7TM and B8TM) werepre-treated with ultrasonic energy in order to increase clay exfoliation yields. Polymeric nanocompositeswere characterized by XRPD, DSC, TGA, DLS and NMR. The results revealed a new exfoliationmethod and new intercalated nanocomposites. High clay load was used to obtain the nanocomposites,which enables its application at an industrial scale. These nanocomposites could be broadly appliedacross the pharmaceutical, medical and food industries.

Steady-State and Transient Response Analysis of DSSC Based on Electron Diffusion Coefficient and Chemical Capacitance

J. C. Gallegos,J. Manriquez,R. Rodriguez,S. Vargas,D. Rangel The Korean Electrochemical Society 2024 Journal of electrochemical science and technology Vol.15 No.2

A study of the transition from transitory state to steady state in DSSCs based on natural dyes is presented; cochineal was used as dye and Li⁺, Na⁺, and K⁺ were the ions added to the electrolyte. The photocurrent profiles were obtained as a function of time. Several DSSCs were prepared with different cations and their role and the transitory-to-steady transition was determined. A novel hybrid charge carrier source model based on the Heaviside function H(t) and the Lambert-Beer law, was developed and applied to analysis of the transient response of the output photocurrent. Additionally, the maximum effective light absorption coefficient α and the electronic extraction rate κ for each ion were determined: ${\alpha}_{Li^+,Na^+,K^+}\,=\,(0.486,\,0.00085,\,0.1126)\,cm^{-1}$, and also the electronic extraction rate ${\kappa}^{Li^+,Na^+,K^+}_{ext.}\,=\,(1410,\,19.07,\,19.69)\,cm\,s^{-1}$. The impedance model using Fick's second law was developed for carrier recombination to characterize the photocurrent.