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RISS 인기검색어
- 검색키워드
- 저자 : E. García-Hernández (검색결과 5 건)
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E. García-Hernández,C.G. Aguilar-Madera,E.C. Herrera-Hernández,R. Ocampo-Pérez,E. Bailón-García,Farid B. Cortés 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.93 No.-
In this work, a mathematical formulation based on fundamental principles of momentum and masstransport with a kinetic adsorption model at the liquid-solid interface is proposed. This formulation wasnumerically solved and used for the interpretation of adsorption rate data of phenol onto an activatedcarbon cloth in a stirred tank adsorber under different agitation rates. The mathematical model solutionwas compared with the obtained by mathematical models that neglect the local velocity andconcentration profiles in the solution; external mass transfer model (EMTM) and thefirst-order kineticmodel (FOM). The results showed that under all studied stirring speeds (30 200 rpm) the proposedmodel was able to capture the dynamics of the concentration decay curves, while EMTM and FOM modelswere only able to interpret the data at high stirring speeds, indicating that velocity profiles play animportant role during phenol adsorption. Particular “wake zones” were identified behind the mobileadsorbent, which importantly promotes the transport of solute toward the activated carbon cloth. As aresult, it was found that convective transport is much more important than diffusive transport in thesolution.
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Curcumin-loaded Polycaprolactone/Collagen Composite Fibers as Potential Antibacterial Wound Dressing
E. San Martín-Martínez,Casañas-Pimentel,A. Almaguer-Flores,G. Prado-Prone,A. García-García,C. Landa-Solís,A. Hernández-Rangel 한국섬유공학회 2022 Fibers and polymers Vol.23 No.11
The development of wound dressings with therapeutical benefits is of great importance in skin tissue engineeringapplications, adding bioactive molecules into biomaterials is a strategy to achieve a better biological response. In this study,four different concentrations of curcumin (CUR; 5, 10, 15 and 20 by weight in relation to the PCL content) were incorporatedinto solutions composed of polycaprolactone (PCL) and collagen (COL) for the manufacture of electrospun fibers. The PCLCOL-CUR fibers were physicochemically characterized in terms of their morphology, wettability, degradation rate,mechanical behavior, and cumulative curcumin release. The in vitro biological properties of the composite membranes werealso evaluated. The results indicated that the membranes have diameters on average of approximately 200 nm. The wateruptake was adequate for exudates remotion in a wound, and the degradation rate of the fibers was highly appropriate toachieve complete skin tissue regeneration. The addition of CUR to composite membranes produced a significant increase inthe mechanical properties which indicate a satisfactory clinical handling. The incorporation of CUR produced a significantdecrease in the planktonic growth of S. aureus over time, however, the antibacterial effect against E. coli was limited, thepresence of CUR did not cause the inhibition of its growth. Finally, the viability of human dermal fibroblasts seeded on thetop of the membranes indicated the cytotoxic dosage effect of CUR, the two highest CUR concentrations produced asignificant loss of cell viability. Overall, our results suggested that the CUR-loaded PCL-COL composite membranes arepromising candidates for use as antibacterial dressings to enhance clinical wound management.
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Physical Properties of the Sr4Al6O12SO4 Ceramic Compound
J.A. Rodríguez-García,E. Rocha-Rangel,J. López Hernández,C.A. Hernández Bocanegra,A.L. Leal Cruz,J.M. Almanza Robles,J. Torres Torres 한양대학교 세라믹연구소 2017 Journal of Ceramic Processing Research Vol.18 No.11
The Sr4Al6O12SO4 ceramic compound was synthesized by a solid state reaction starting from stoichiometric mixtures of 3 : 3 : 1 molar ratio of reactive grade of SrCO3, Al2O3 and SrSO4, respectively. Cylindrical samples were confirmed by uniaxial pressing at 100 MPa and were heat treated at 1400 oC during 4 hrs. Subsequently, the samples were ground and re-conformed in cylindrical shape samples by uniaxial pressing at 300 MPa. The new samples were heat treated at 1400 oC during 24 hrs. This process was done in order to increase density of the samples. The Sr4Al6O12SO4 ceramic compound was characterized by the study of its physical properties such as: density, micro-hardness, thermal expansion and stability, enthalpy of formation, magnetic properties and electrical conductivity. Experimental results show that the maximum density obtained for the Sr4Al6O12SO4 ceramic compound was 2.913 grcm−3, with thermal expansion coefficient of 10.12E−06(oC−1); it also presents an enthalpy of 2.3 KJmol-1 and an excellent thermal stability at elevated temperatures in different atmospheres. In addition, the Sr4Al6O12SO4 ceramic compound is neither electrically conductive nor magnetic.
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Effect of Ag doping on the crystallization and phase transition of TiO2 nanoparticles
J. García-Serrano,E. Gómez-Hernández,M. Ocampo-Fernández,U. Pal 한국물리학회 2009 Current Applied Physics Vol.9 No.5
TiO2 nanoparticles doped with different Ag contents were prepared by a modified sol–gel method, using titanium tetraisopropoxide and silver nitrate as precursors and 2-propanol as solvent. Silver was incorporated into the TiO2 matrix via decomposition of AgNO3 during thermal treatment in different atmospheres. Effects of Ag doping on the crystallization and phase transition of the TiO2 nanoparticles were studied using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Raman spectroscopy techniques. While air annealing incorporates silver into TiO2 matrix in silver oxide form, annealing in nitrogen incorporates metallic silver into TiO2. Formation of silver oxide increases the thermal stability of the TiO2 particles. Silver oxide affects the crystallization process of TiO2 particles and the temperature of transition form anatase to rutile. On the other hand, presence of metallic silver in the samples annealed in nitrogen atmosphere decreases the temperature of phase transition of TiO2 nanoparticles.
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José Aurelio Sosa,José Ramón Laines,David Salvador García,Rafael Hernández,Mark Zappi,Alejandra E. Espinosa de los Monteros 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.3
The energy growing demand and the international environmental policies contribute to the use of renewable energy sources. Among these sources, biogas has acquired great relevance due to its energetic similarity to fuels such as liquefied petroleum gas (LPG) and natural gas (NG). However, biogas needs to be upgraded by removing CO2 and trace gases to obtain biomethane (>85% CH4). This review identifies and classifies seven techniques used in biogas upgrading, reported in academic and scientific publications. A 13-year review period (2008–2021) was considered. Lineal regression was used to analyze the publications number per year. Membranes use represents the largest proportion of publications (33%), while activated carbon (AC) reaches only 22%. However, the use and application of AC obtained the best trend as a publication topic, with a maximum value of R2 = 0.7882. This review documents publish works on obtaining and applying AC in biogas enrichment processes. It includes a review of the characteristics and generation rates of various residual lignocellulosic materials used in the synthesis of AC, the synthesis processes, the characterization techniques, and the final adsorption capacities.
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