Hydrolysis catalyst effect on the textural and structural properties of sol-gel mixed oxides TiO₂-CeO₂

Félix Galindo-Hernández,Gloria del Ángel,Carlos Guzmán,Ricardo Gómez 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

Sol-gel TiO2-CeO2 semiconductors were synthesized at pH 3 and 9 using titanium alkoxide as the initial reactant; and either nitric acid or ammonium hydroxide as hydrolysis agents. The gels annealed at 473, 673 and 873 K were characterized by nitrogen adsorption,X-ray diffraction and Raman spectroscopy. The surface fractal dimension, crystallite size, titanium deficiency and electron density were calculated by the Frenkel-Halsey-Hill method, Rietveld refinement, and Fourier electron density map, respectively. Mesoporous materials showing high specific surface areas (250-99m2/g for pH 3 and 267-88 m2/g for pH 9) were obtained in both preparations. Anatase and anatase-cerianite crystalline phases were observed by X-ray diffraction in the samples prepared at pH 3 and pH 9 respectively. Nanocrystalline structures (from 7.1 to 43.6 nm) and an important titanium deficiency, depending on the synthesis conditions are reported. The Fourier electron density maps showed that for the semiconductors prepared at pH 3 the electron density was contracted in comparison with the samples synthesized at pH 9 where enlarged electron density maps were observed. A good agreement between the electron density maps and the surface fractal dimensions was obtained. Sol-gel TiO2-CeO2 semiconductors were synthesized at pH 3 and 9 using titanium alkoxide as the initial reactant; and either nitric acid or ammonium hydroxide as hydrolysis agents. The gels annealed at 473, 673 and 873 K were characterized by nitrogen adsorption,X-ray diffraction and Raman spectroscopy. The surface fractal dimension, crystallite size, titanium deficiency and electron density were calculated by the Frenkel-Halsey-Hill method, Rietveld refinement, and Fourier electron density map, respectively. Mesoporous materials showing high specific surface areas (250-99m2/g for pH 3 and 267-88 m2/g for pH 9) were obtained in both preparations. Anatase and anatase-cerianite crystalline phases were observed by X-ray diffraction in the samples prepared at pH 3 and pH 9 respectively. Nanocrystalline structures (from 7.1 to 43.6 nm) and an important titanium deficiency, depending on the synthesis conditions are reported. The Fourier electron density maps showed that for the semiconductors prepared at pH 3 the electron density was contracted in comparison with the samples synthesized at pH 9 where enlarged electron density maps were observed. A good agreement between the electron density maps and the surface fractal dimensions was obtained.

Model of Interaction for Academia-Industry-Government to promote the development of human resources in Information Technologies using E-learning

Lourdes-Sánchez-Guerrero,Víctor Gómez-Quintero,Mariem Henaine-Abed,Juan Contreras-Castillo,Ricardo Acosta-Díaz APEC국제교육협력원 2008 Asia-Pacific Cybereducation Journal Vol.4 No.2

Intra-aneurysmatic thrombectomy in a distal anterior cerebral artery aneurysm

Juan Luis Gómez-Amador,Leoncio Alberto Tovar-Romero,Andrea Castillo-Matus,Ricardo Marian-Magaña,Jorge Fernando Aragón-Arreola,Marcos Vinicius Sangrador-Deitos,Alan Hernández-Hernández,Germán López-Val 대한뇌혈관외과학회 2023 Journal of Cerebrovascular and Endovascular Neuros Vol.25 No.4

Thrombectomy procedures following intra-aneurysmatic lesions are extremely rare, and few cases have been reported. This article describes a microsurgical intra-aneurysmatic thrombectomy (MIaT) for a distal anterior cerebral artery (DACA) aneurysm. We present the case of a 48-year-old female that was admitted to the emergency room, showing neurologic deterioration with focal deficits. A computed tomography angiography (CTA) scan revealed an aneurysm located in the distal segment of the left anterior cerebral artery. During the surgical procedure, after clipping, a wellformed clot was visualized through the aneurysm’s wall obstructing the left DACA flow. We proceeded to open the aneurysm’s dome to remove the thrombus and clip the aneurysm neck, re-establishing the flow of the left DACA.Intra-aneurysmatic thrombosis can occur as a complication during clipping, obstructing the distal flow of vital arteries and causing fatal results in the patient’s postoperative status. MIaT is a good technique for restoring the flow of the affected vessel and allows a secure aneurysm clipping after thrombus removal.

Unilateral approach for bilateral clipping of posterior communicating artery aneurysms in a hybrid operating room: A technical note

Juan Luis Gómez-Amador,Pablo David Guerrero-Suárez,Jaime Jesús Martínez-Anda,Jorge Fernando Aragón-Arreola,Andrea Castillo-Matus,Ricardo Marian-Magaña,Marcos V Sangrador-Deitos,Alan Hernández-Hernánde 대한뇌혈관외과학회 2023 Journal of Cerebrovascular and Endovascular Neuros Vol.25 No.4

Bilateral posterior communicating (pComm) artery aneurysms represent only 2% of mirror intracranial aneurysms. Usually, these are surgically approached through bilateral craniotomies for clipping. We present the case of a 50-year-old female presenting with headache and horizontal diplopia. Neurological examination revealed a left oculomotor palsy, with no other neurological deficits. Imaging studies revealed bilateral aneurysmatic lesions in both internal carotid arteries (ICA). A conventional left pterional approach was planned in order to treat the symptomatic aneurysm, and, if deemed feasible, a contralateral clipping through the same approach. The procedure was performed in a hybrid operating room (HOR), performing an intraoperative digital subtraction angiography (DSA) and roadmapping assistance during dissection and clipping. Transoperatively, a post-fixed optic chiasm was identified, with a wide interoptic space, which allowed us to perform the contralateral clipping through a unilateral approach. This technique for clipping bilateral pComm aneurysms can be performed when the proper anatomical features are met.

Laparoscopic Liver Resection of Segments 7 and 8: from the Initial Restrictions to the Current Indications

Victor Lopez-Lopez,Yusuke Ome,Yusuke Kawamoto,Alvaro Gómez Ruiz,Ricardo Robles Campos,Goro Honda 대한내시경복강경외과학회 2020 Journal of Minimally Invasive Surgery Vol.23 No.1

Since the beginning of laparoscopic liver surgery, resection of the posterosuperior segments has been considered one of the most challenging procedure due to its difficult access. The main drawbacks of the laparoscopic approach to dome lesions are poor visualization, the difficulty of instrumentation and the greater complexity in the control of bleeding. In the evolution of minimally invasive techniques from hybrid techniques to the current purely laparoscopic approaches, the different authors have established gradually the currents indications and surgical techniques to operate these segments with a similar feasibility and safety than open approach. The standardization in the patient position, the use of intercostal trocars, the learning curve in laparoscopic liver surgery, the management of the hepatic blood flow and the refinement of the technique in the extrahepatic and intrahepatic Glissonean pedicle approaches, has allowed to leave behind the initial contraindications about the laparoscopic approach in these segments. In the present review of the literature, the accumulated experience of the different groups in minimally invasive liver surgery together with the technological advances in the different laparoscopic devices have facilitated the resection of tumors in segments 7 and 8 with similar and even better results than open surgery.

Bi2InTaO7 compounds as promising photocatalysts for marine plankton removal

Leticia M. Torres-Martínez,Isaías Juárez-Ramírez,Juan S. Ramos-Garza,Francisco Vázquez-Acosta,Ricardo Gómez,ZhengYi Fu,Soo Wohn Lee 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.1

The removal of marine plankton, red (Amphidium carterae), and green (Tetraselmis suecica) tide algae, by heterogeneous photocatalysis was carried out using pyrochlore-type semiconductors. The semiconductor, Bi2InTaO7 , was prepared by the solgel method and a solid state reaction. The XRD patterns evidence formation of the pyrochlore phase in the sol-gel materials calcined at low temperatures (600-800 oC). Nanostructured sol-gel materials were observed by SEM. The sol-gel preparation allowed the formation of the pyrochlore-type compound with specific surface areas (7-13 m2g−1) higher than the solid obtained by solid state preparation (< 5 m2g−1). Band gap (Eg) values between 2.1-2.7 eV determined by UV-Vis spectroscopy were obtained. Bi2InTaO7 photocatalysts prepared by the sol-gel method were able to eliminate Tetraselmis suecica and Amphidium carterae algae totally after 50 minutes of UV-irradiation, whereas Bi2InTaO7 by solid state preparation needed more than 1 h.

Combination of Mn oxidation states improves the photocatalytic degradation of phenol with ZnAl LDH materials without a source of O₂ in the reaction system

Morales-Mendoza, Getsemani,Alvarez-Lemus, Mayra,Ló,pez, Rosendo,Tzompantzi, Francisco,Adhikari, Rajesh,Lee, Soo Wohn,Torres-Martí,nez, Leticia M.,Gó,mez, Ricardo Elsevier 2016 CATALYSIS TODAY - Vol.266 No.-

<P><B>Abstract</B></P> <P>Mn-doped Zn/Al layered double hydroxides (LDH) materials were synthesized by the co-precipitation method. X-ray diffraction (XRD) analysis confirmed the polytype structure of LDH materials obtained as well as the successful incorporation of Mn into the structure. Atomic absorption spectroscopy (AAS) and energy dispersive X-ray spectroscopy (EDS) studies showed a well dispersion of Mn and a good correlation between the nominal and experimental composition. Scanning electron microscopy (SEM) revealed the formation of grains close to 1μm length. Energy band gap (Eg) of the solids determined by UV–vis diffuse reflectance spectroscopy (DRS) showed high photoresponse in the ultraviolet (UV) region, which was increased with Mn incorporation into the LDH structure. The LDH materials were evaluated in the photocatalytic degradation of phenol in aqueous medium, under UV radiation with and without O<SUB>2</SUB> source in the reaction system. The results showed that the O<SUB>2</SUB> is not an effective electron scavenger as usually occurs in TiO<SUB>2</SUB> photocatalyst. The Mn effect in the photocatalytic activity was notably marked in anaerobic condition however in aerobic or anaerobic conditions the presence of Mn increases the photoactivity. The phenol mineralization reached in anaerobic conditions was 95% (1.5ppm) of the initial concentration (30ppm) and it is maintained constant after 6h of radiation while in aerobic conditions the TOC reaches only 55% (13.5ppm). The role of Mn as charges separator is discussed and a suitable mechanism is proposed. This study shows that the Mn doped-Zn/Al LDH materials could be a promising photocatalysts under anaerobic conditions for the removal of phenol from aqueous medium.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnAl LDH rebuilt in phenol solution have not capacity to open the interlayer space. </LI> <LI> A source of O<SUB>2</SUB> have not influence in the phenol photooxidation with ZnAl LDH. </LI> <LI> Mn doped-ZnAl LDH increases the optical properties of absorption. </LI> <LI> The role as electron and hole trap of Mn takes advantage to separate charge. </LI> <LI> The Mn incorporation in ZnAl LDH materials improves the photocatalytic activity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>