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Karla F. García-Verdugo,Andya J. Ramírez-Irigoyen,Mónica Castillo-Ortega,Dora E. Rodríguez-Félix,Jesús M. Quiroz-Castillo,Judith Tánori-Córdova,Francisco Rodríguez-Félix,Antonio Ledezma-Pérez,Teresa d 한국고분자학회 2022 Macromolecular Research Vol.30 No.6
A novel semi-interpenetrating polymer network (s-IPN) based on the entrapment of a thermosensitive polymer, the poly(vinyl methyl ether) (PVME), within a crosslinked 3D structure of poly(vinyl alcohol) (PVA) and poly(vinyl methyl etheralt- maleic acid) (COP) was synthesized by an autoclaving process. The preparation method avoids the use of toxic crosslinkers and allows the simultaneous sterilization of material. The PVA/COP/PVME hydrogel were characterized by Fourier transform infrared spectroscopy, thermal techniques, swelling kinetic measurements, scanning electron microscopy, and rheological analysis. The entrapment of PVME within the hydrated polymer framework significantly modified its transition temperature at pH 7.4 and pH 3 conditions. The swelling kinetics of the s-IPN were dependent on pH (7.4, 3 and 1), and temperature (25 and 37℃). The interpenetrated polymer chains reduced the internal pore sizes of crosslinked network without altering its elastic, solid-like behavior. The loading and in vitro release of 5-fluorouracil, a chemotherapeutic agent, from hydrogel systems were studied at different temperature and pH values. The hydrogels showed a sustained drug release up to 5 h at 37℃, in different pH media. The s-IPN exhibited a promising performance for a range of biomedical applications, in particular, for the controlled drug delivery in response to the pH and temperature conditions.
M. I. Barrena,J. M. Gómez de Salazar,J. M. Vázquez,García-Cano,J. M. Guilemany 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.4
Protective surface coatings on an AZ91D magnesium alloy were formed in an atmosphere mixture ofnitrogen and 1,1,1,2-tetrafluoroethane (HFC-134a). The surface composition and microstructure were characterizedusing X-ray diffraction analysis and scanning electron microscopy, respectively. The cross-sectionmorphologies of the coatings show that an increase in conversion time results in an increase in thecontinuity and compactness of the coating generated on the surface of the AZ91D alloy. The corrosionresistance tests performed by immersion into 3.5% NaCl solutions were investigated by electrochemicalmeasurements. The results showed that the coated samples had higher corrosion resistance than the uncoatedalloy. On the other hand, the corrosion density of the coated samples decreased by increasing theconversion time by about two orders of magnitude, compared with the un-coated samples. This behaviouris attributed to the formation of a protective surface film constituted mainly for MgF2, together with otherphases. The nature of these phases depends on the process conditions.
The effect of synthesis parameters on the production of titania nanostructured spherical aggregates
M. E. Contreras-García,M. L. García-Benjume,M. I. Espitia-Cabrera 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.2
Anatase submicrometre nanostructured spherical aggregates have been obtained with a sol-gel synthesis assisted by Tween-20 as a surfactant. A low hydrolysis rate in room conditions and calcination at low temperatures were employed. Effective photocatalytic activities of up to 73% were obtained in the photodegradation of the methylene blue reaction. The effect of the synthesis parameters on the sizes of the spherical agglomerates obtained and on the crystallite size were evaluated; these parameters were the surfactant content, the molar concentration of the precursor titanium butoxide, and their relative ratios. The crystallite size had the main effect of obtaining good photocatalytic behavior, with a linear dependence on the photocatalytic activities. The morphology and anatase structure were determined by transmission electron microscopy. Use of the proposed synthesis made it possible to obtain only the anatase phase with small crystal sizes.
Comparison of physicochemical properties of bio and commercial hydroxyapatite
A.L. Giraldo-Betancur,D.G. Espinosa-Arbelaez,A. del Real-López,B.M. Millan-Malo,E.M. Rivera-Muñoz,E. Gutierrez-Cortez,P. Pineda-Gomez,S. Jimenez-Sandoval,M.E. Rodriguez-García 한국물리학회 2013 Current Applied Physics Vol.13 No.7
This article reports a physicochemical comparison of synthetic and biological Hydroxyapatite (HAp). Eight samples were separated into two groups: bio and commercial hydroxyapatite (bio-HAp and commercial-HAp). The bio-HAp group containing defat, alkaline, and calcined samples taken from bovine bone were obtained by using three different treatments, in order to establish their effect on the final product quality. The commercial-HAp group, from different sources: NIST, sigma, apafill G, coralina, and biograft, were analyzed and compared with the bio-HAp results. Thermogravimetric analysis (TG) was used in order to establish thermal degradation of the samples; structural behavior was then analyzed by X-Ray Diffraction (XRD) to found the crystalline phases, as well as the crystalline quality. Fourier Transform Infrared Spectroscopy (FTIR) was performed in order to identify the corresponding HAp functional groups within the samples. The surface morphology was analyzed by Scanning Electron Microscopy (SEM) and the elemental composition was established by using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). It was found that the calcination process obtains HAp with comparable quality to the commercial samples. A crystallinity greater than 62% after the alkaline process was found. Additionally, the surface of the alkaline sample presents a transition behavior between dense and porous morphology.
A. Gil,A.M. García,M. Fernández,M.A. Vicente,B. González-Rodríguez,V. Rives,S.A. Korili 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.53 No.-
Photocatalysts composed of titanium dioxide modified with B, F, N and P have been synthesized, characterized and applied to the degradation of caffeine, diclofenac, ibuprofen and salicylic acid. The modified TiO2 samples were prepared by the sol–gel technique starting from titanium(IV) isopropoxide and using H3BO3, NH4F, N(C2H5OH)3 and H3PO4 as precursors of the modifiers, with the content varying between 0 and 5 wt%. Structural characterization was based on nitrogen physisorption at 196 C, powder X-ray diffraction (PXRD), simultaneous thermogravimetric/differential thermal analysis (TG/ DTA) and X-ray photoelectron spectroscopy (XPS). The structural properties of the modified TiO2 solids were significantly different depending on the nature and amount of modifiers and the calcination temperature. TiO2 in the anatase phase was obtained in all cases and was stable upon calcination at 400 C. The photocatalytic degradation of caffeine, diclofenac, ibuprofen and salicylic acid by modified TiO2 was investigated under ultraviolet irradiation at 25 C. The photocatalytic degradation behavior followed the order: caffeine > diclofenac = ibuprofen > salicylic acid. B-doped TiO2 was the most efficient catalyst in the degradation of these selected emerging contaminants.
Gemini lipopeptides as vaccine adjuvants: a new role for these versatile carriers
Lucía Daniela Grippo,Ivana Gabriela Reidel,María Inés García,Alexis Streu,Diana María Müller,Carolina Melania Veaute 대한백신학회 2020 Clinical and Experimental Vaccine Research Vol.9 No.2
The design of subunit vaccines requires new adjuvant systems. We designed and synthesized new lipopeptides (cysteine-based) of low molecular weight with different hydrophobic chains that dimerize becoming gemini lipopeptides. They were characterized and their adjuvant capacity was tested in mice by the inoculation of a protein antigen formulated with the lipopeptides, with and without the addition of CpG-oligodeoxynucleotides. Formulations were able to induce an immune response and produced no adverse effects. An adjuvant ability is described for the first time for this type of molecules.
Slip-resistant bolted connections under freeze-thaw cycles and low temperature
A. Fuente-García,M.A. Serrano-López,C. López-Colina,F. López-Gayarre 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.48 No.3
There are many examples of steel structures subjected to severe environmental conditions with bolted connections directly exposed to extreme climatic agents such as freeze-thaw cycles or low temperatures. Some examples are: steel bridges, mining transfer towers, wind towers... These service conditions neither are included in Eurocode 3 or EN1090-2, nor there are references in other international standards. In this experimental research, 46 specimens of non-slip joints with HV M20 bolts and four different types of contact surfaces have been studied. Half of the specimens were subjected to fourteen twelve-hours freezethaw cycles, with periodic immersion in water and temperature oscillation. Subsequently, half of the connections were subjected to a slip test under monotonic load at temperature of -20 ± 0.5 ºC and the other half at room temperature. The results were compared with others equal joints not subjected to freeze-thaw cycles and kept at room temperature for the same time. This finally resulted in 4 sets of joints by combining the freeze-thaw degradation or not with the low-temperature conditions or not in the slip testing. Therefore, a total of 16 different conditions were studied by also considering 4 different contact surfaces between the joined plates in each set. The results obtained show influence of environmental conditions on the slip resistant capacity of these joints.
Development of a gamma irradiation loop to evaluate the performance of a EURO-GANEX process
I. Sanchez-García,H. Galan,A. Núnez,J.M. Perlado,J. Cobos 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.5
A new irradiation loop design has been developed, which provides the ability to carry out radiolyticresistance studies of extraction systems simulating process relevant conditions in an easy and simpleway. The step-by-step loop configuration permits an easy modification of settings and has a relative lowvolume requirement. This irradiation loop has been initially set up to test the main EURO-GANEX processsteps: the lanthanide (Ln) and actinide (An) co-extraction followed by the transuranic (TRU) stripping. The performance and changes in the composition have been analyzed during the irradiation experimentby different techniques: gamma spectroscopy and ICP-MS for the extraction and corrosion behavior ofthe full system, and HPLC-MS and Raman spectroscopy to determine the degradation of the organic andaqueous solvents, respectively. The Ln and An co-extraction step and the corrosion that occurred duringthe first irradiation step revealed the favorable expected results according to literature. The effects ofacidity changes occurred during the irradiation process, the presence of stainless corrosion products insolution as well as the new possible degradation compounds have been explored in the An stripping step. The results obtained demonstrate the importance of developing realistic irradiation experiments wheredifferent factors affecting the performance can be easily studied and isolated
Paola A. Escalante Abril,Miguel Fdo. Salazar,Nubia L. López García,Mónica N. Madrazo Moya,Yadir U. Zamora Guerra,Yadira Gandhi Mata Mendoza,Erick Gómez Apo,Laura G. Chávez Macías 대한병리학회 2015 Journal of Pathology and Translational Medicine Vol.49 No.6
We report a 50-year-old woman with no relevant clinical history who presented with headache and loss of memory. Magnetic resonance imaging showed a left parieto-temporal mass with annular enhancement after contrast media administration, rendering a radiological diagnosis of high-grade astrocytic neoplasm. Tumour sampling was performed but the patient ultimately died as a result of disease. Microscopically, the lesion had areas of glioblastoma mixed with a benign mesenchymal constituent; the former showed hypercellularity, endothelial proliferation, high mitotic activity and necrosis, while the latter showed fascicles of long spindle cells surrounded by collagen and reticulin fibers. With approximately 40 previously reported cases, gliofibroma is a rare neoplasm defined as either glio-desmoplastic or glial/benign mesenchymal. As shown in our case, its prognosis is apparently determined by the degree of anaplasia of the glial component.