Particle size effect of LiAlSiO₄on the thermal expansion of SiC porous materials

I. Juárez-Ramírez,K. Matsumaru,K. Ishizaki,L.M. Torres-Martínez 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.5

This paper reports the effect of the particle size of LiAlSiO4 on the thermal expansion and Young’s modulus of low thermal expansion (LTE) coefficient of porous materials using silicon carbide (SiC), vitrified bonding material (VBM) and lithium aluminum silicate (LiAlSiO4) at 850 oC. According to the XRD results, there is no reaction between the raw materials during the sintering process. SEM analysis revealed the presence of an internal porous structure with a pore size less than 4 micrometers. It was found that decreasing the particle size of LiAlSiO4 by almost 4 times reduces the porosity, keeping a low thermal expansion coefficient, but the Young’s modulus increases 50%. This paper reports the effect of the particle size of LiAlSiO4 on the thermal expansion and Young’s modulus of low thermal expansion (LTE) coefficient of porous materials using silicon carbide (SiC), vitrified bonding material (VBM) and lithium aluminum silicate (LiAlSiO4) at 850 oC. According to the XRD results, there is no reaction between the raw materials during the sintering process. SEM analysis revealed the presence of an internal porous structure with a pore size less than 4 micrometers. It was found that decreasing the particle size of LiAlSiO4 by almost 4 times reduces the porosity, keeping a low thermal expansion coefficient, but the Young’s modulus increases 50%.

Active Disturbance Rejection Control of the Inertia Wheel Pendulum through a Tangent Linearization Approach

Mario Ramírez-Neria,Hebertt Sira-Ramírez,Rubén Garrido-Moctezuma,Alberto Luviano-Juárez 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.1

A flatness based approach is proposed for the linear Active Disturbance Rejection Control (ADRC) stabilizationof a nonlinear inertia wheel pendulum (IWP) around its unstable equilibrium point, subject to unmodelleddynamics and disturbances. The approach exploits the cascade structure, provided by the flatness property, of thetangent linearization of the underactuated system which allows designing a high gain linear cascaded Extended StateObserver (ESO) of the Generalized Proportional Integral (GPI) type. This class of linear observers is employed tobuild an Active Disturbance Rejection Control controller with a lower order of complexity regarding other ADRCclassic schemes. Experimental results demonstrate the effectiveness and feasibility of the proposed approach, aswell as a better behavior with respect to a classic control technique in the presence of disturbances.

Silver nanoparticles incorporated into Na₂Ti6O13 microfibers

V. Rodríguez-González,I. Juárez-Ramírez,R. Zanella,M.E. Zarazúa,L.M. Torres-Martínez 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

This research is concerned with novel semiconductor composites of sodium hexatitanate oxide (Na2Ti6O13), and silver metallic nanoparticles. The Na2Ti6O13 was prepared by two methods, a sol-gel process and a solid state reaction. The silver nanoparticles were incorporated into the titanate by a deposition-precipitation technique, using NaOH as precipitation agent in the dark. Ag/Na2Ti6O13 microfibers were obtained by the sol-gel method, meanwhile octagonal microbar agglomerates were the product of the solid state reaction. The SEM-TEM observations showed silver particles with a nanometric size (5-7 nm); and fibrillar structures in the sol-gel sodium titanates. The UV-Vis-RD spectroscopy showed a blue shift Eg from 3.3 to 3.4 nm; and a plasmon surface resonance in the visible region. These materials are proposed as potential photocatalysts for contaminated water purification. This research is concerned with novel semiconductor composites of sodium hexatitanate oxide (Na2Ti6O13), and silver metallic nanoparticles. The Na2Ti6O13 was prepared by two methods, a sol-gel process and a solid state reaction. The silver nanoparticles were incorporated into the titanate by a deposition-precipitation technique, using NaOH as precipitation agent in the dark. Ag/Na2Ti6O13 microfibers were obtained by the sol-gel method, meanwhile octagonal microbar agglomerates were the product of the solid state reaction. The SEM-TEM observations showed silver particles with a nanometric size (5-7 nm); and fibrillar structures in the sol-gel sodium titanates. The UV-Vis-RD spectroscopy showed a blue shift Eg from 3.3 to 3.4 nm; and a plasmon surface resonance in the visible region. These materials are proposed as potential photocatalysts for contaminated water purification.

A study of the impact of high-speed sealing parameter gradients on the seal strength in a multilayer polypropylene film

Jorge E. Uribe-Juárez,Ma. Pilar Corona-Lira,Alejandro C. Ramírez-Reivich 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.5

Multilayer polymer films continue to be used in food packaging high-speed lines;this research focuses on obtaining better film adhesion under controlled sealing conditions. The present work aims to describe the presence of temperature gradients in the body of the sealing jaw, the dwell time gradients, and the surface pressure gradients, experimenting with a highspeed sealing process. The samples' adhesion was measured using the peeling test, and the peeling graphs of the tests were analyzed to observe the differences and similarities of each sealing parameter combination. Experimental data were used to generate the surface response families of the seal strength of multilayer polymer film. The model describes, in a 3D space, the influence zones that sealing parameter gradients had on the seal strength. The surface model and experimental data indicate that temperature is a decisive parameter of seal strength.

Synthesis of γ-Al₂O₃ nanopowder by the sol-gel method: Effect of different acid precursors on the superficial, morphological and structural properties

Arquímedes Cruz-López,Odilón Vázquez Cuchillo,Isaías Juárez Ramírez,Lilia M. Bautista-Carrillo,Elvira Zarazua-Morin 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.5

The main aim of this investigation is to study the effect of three acid precursors (nitric acid, acetic acid and citric acid) during the synthesis of γ-Al2O3 nanopowder by the sol-gel method. The TEM analyses showed that the γ-Al2O3 prepared by using the strongest acid were irregular nanofibers with a length of 50 nm and a diameter of 5 nm, while the γ-Al2O3 prepared with citric acid showed agglomerates. On the other hand, the SEM analyses showed very similar morphologies. The N2-physisorption analyses confirmed that there is a relationship between the acidity and the surface area; and between the presence of mesopores and micropores on the surface of the synthesized Al2O3. The effect of the acid strength on the surface area was as follows: nitric acid (347 m2·g−1) > acetic acid (252 m2·g−1) > citric acid (164 m2·g−1). In addition, the XRD results confirmed that for all the samples thermally treated at 600 oC, the main phase was γ-Al2O3; nevertheless, the thermal analyses showed that the γ-Al2O3 synthesized with the weakest acid was not stable above 600 oC. The main aim of this investigation is to study the effect of three acid precursors (nitric acid, acetic acid and citric acid) during the synthesis of γ-Al2O3 nanopowder by the sol-gel method. The TEM analyses showed that the γ-Al2O3 prepared by using the strongest acid were irregular nanofibers with a length of 50 nm and a diameter of 5 nm, while the γ-Al2O3 prepared with citric acid showed agglomerates. On the other hand, the SEM analyses showed very similar morphologies. The N2-physisorption analyses confirmed that there is a relationship between the acidity and the surface area; and between the presence of mesopores and micropores on the surface of the synthesized Al2O3. The effect of the acid strength on the surface area was as follows: nitric acid (347 m2·g−1) > acetic acid (252 m2·g−1) > citric acid (164 m2·g−1). In addition, the XRD results confirmed that for all the samples thermally treated at 600 oC, the main phase was γ-Al2O3; nevertheless, the thermal analyses showed that the γ-Al2O3 synthesized with the weakest acid was not stable above 600 oC.

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.

Volatiles from Marina neglecta: Biocide effect on insect vectors of tropical diseases in Southern Mexico

Pacheco-Hernández Yesenia,Jonnathan Castro-Juárez Carlos,Alberto Ramírez-García Sergio,Cruz-Durán Ramiro,Lozoya-Gloria Edmundo,Villa-Ruano Nemesio 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.2

Preventive measures based in the control of insect vectors are considered as the best choice to decrease the incidence of insect-borne diseases. Herein we report on the volatile content of the leaf essential oils from Marina neglecta, a medicinal plant distributed in the tropical regions of southern Mexico. In order to investigate the chemical variation of the essential oils, a volatile screening was performed during the four seasons of the years 2016–2019. Simultaneously, their biological activity was tested on distinct life stages of Meccus pallidipennis, M. bassolsae, Aedes aegypti and A. albopictus. Essential oils were mainly constituted of β-pinene (>30%) β-car yophyllene (>25%) and germacrene D (>13%). Dorsal-abdomen application of essential oils on triatomines, revealed an efficient LC 50 for nymphs of the stages I to III (4 µg/insect), nymphs of the stages IV to V (5–6 µg/ insect), and adults (7–8 µg/insect). The LT 50 for the stages I to III was between 6 and 8 h, whereas that for the stages IV to V and adults oscillated between 12 and 16 h and 22 to 26 h, respectively. Fumigation experiments performed on nymph V, demonstrated that 300 µg L − 1 air produced 100% mortality after 72 h post-treatment. Among tested volatiles, β-pinene and β-caryophyllene produced a comparable mortality rate (p < 0.01) than that of essential oils in the stages assayed. Essential oils showed strong larvicidal (LC 50 , 24–36 µg mL − 1 ) and adul ticidal (35–48 µg mL − 1 ) activities in mosquito species with an LT 50 of 4.5 h and 25–35 min, respectively. The evaluation of β-pinene produced a significant mortality rate (p < 0.01) in larvae whereas germacrene D was the most effective volatile (p < 0.01) against adults of both mosquito species. According to our results, β-pinene was the most effective volatile against the four insect species evaluated and its effect was comparable to that of the essential oil.

Synthesis of Bi₂W₂O9 from an amorphous complex precursor: characterization and evaluation of its photocatalytical properties

A. Martínez-de la Cruz,S. Obregón Alfaro,Leticia M. Torres-Martínez,I. Juárez Ramírez 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.5

Bismuth tungstate Bi2W2O9 has been synthesized using diethylenetriaminepentaacetic acid (H5DTPA), an organic chelating agent of metals in an aqueous solution. The formation of the oxide was followed through characterization techniques such as XRD, TGA/DTA, and SEM. The optimum temperature to decompose the organic matrix and to form Bi2W2O9 was determined to be around 720 oC. Below this temperature, Bi2W2O9 was formed with a high content of Bi2WO6. At 720 oC particles of the Bi2W2O9 with a surface area four times higher than that obtained by a solid-state reaction were obtained. The oxide was tested as a photocatalyst on the degradation of aqueous solutions of rhodamine B under VIS radiation. The photodegradation of the dye followed a kinetic first order with an apparent constant, k = 2.8 × 10−3 minute−1and t1/2= 247 minutes for an aqueous solution of 5 mg l−1 of rhodamine B. Bismuth tungstate Bi2W2O9 has been synthesized using diethylenetriaminepentaacetic acid (H5DTPA), an organic chelating agent of metals in an aqueous solution. The formation of the oxide was followed through characterization techniques such as XRD, TGA/DTA, and SEM. The optimum temperature to decompose the organic matrix and to form Bi2W2O9 was determined to be around 720 oC. Below this temperature, Bi2W2O9 was formed with a high content of Bi2WO6. At 720 oC particles of the Bi2W2O9 with a surface area four times higher than that obtained by a solid-state reaction were obtained. The oxide was tested as a photocatalyst on the degradation of aqueous solutions of rhodamine B under VIS radiation. The photodegradation of the dye followed a kinetic first order with an apparent constant, k = 2.8 × 10−3 minute−1and t1/2= 247 minutes for an aqueous solution of 5 mg l−1 of rhodamine B.

Antagonistic Activity of Bacteria Isolated from Apple in Different Fruit Development Stages against Blue Mold Caused by Penicillium expansum

Rocí,o Crystabel Ló,pez-Gonzá,lez,Yara Suhan Juá,rez-Campusano,José,Luis Rodrí,guez-Chá,vez,Guillermo Delgado-Lamas,Sofí,a Marí,a Arvizu Medrano,Ramó,n Á,lv 한국식물병리학회 2021 Plant Pathology Journal Vol.37 No.1

Blue mold caused by Penicillium expansum is one of the most significant postharvest diseases of apples. Some microorganisms associated with the surface of ripen- ing apples possess the ability to inhibit the growth of P. expansum. However, the existing literature about their colonization in the stages before ripening is not explored in depth. This study aims to characterize the antagonistic capacity of bacterial populations from five fruit development stages of ‘Royal Gala’ apples. The re- sults have shown that the density of the bacterial popu- lations decreases throughout the ripening stages of fruit (from 1.0 × 105 to 1.1 × 101 cfu/cm2). A total of 25 bacte- rial morphotypes (corresponding to five genera identi- fied by 16S RNA) were differentiated in which Bacillus stood out as a predominant genus. In the in vitro an- tagonism tests, 10 Bacillus strains (40%) inhibited the mycelial growth of P. expansum from 30.1% to 60.1%, while in fruit bioassays, the same strains reduced the fruit rot ranging from 12% to 66%. Moreover, the bacterial strains with antagonistic activity increased in the ripening fruit stage. B. subtilis subsp. spiziennii M24 obtained the highest antagonistic activity (66.9% of rot reduction). The matrix-assisted laser desorption ioniza- tion-time of flight mass spectrometry analysis revealed that bacteria with antagonistic activity produce anti- fungal lipopeptides from iturin and fengycin families.