Development of nanostructure in ultra-fine anatase powders derived by the low temperature sol gel-solvothermal process

Oliver Muñiz-Serrato,Juan Serrato Rodríguez 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.5

Ultra-fine crystalline anatase nano-powders of less than 6 nm particle size have been obtained at the early stage of crystallization using the one step low temperature non-aqueous sol gel-solvothermal treatment of the Ti(OBu)4 precursor. The solvothermal treatment is held at 110 o C for 10, 20, 40, 60 hours in the presence of 2-etoxiethanol and ethanol as solvent. Nanostructural development is followed by TEM, HRTEM, electron and X Ray diffraction. Particle coarsening by oriented attachment is evidenced by HRTEM observations and by particle growth kinetics during the solvothermal treatment.

Formation of flow coated high catalytic activity thin films from the low temperature sol-gel titanium butoxide precursor

Oliver Muñiz-Serrato,Juan Serrato Rodríguez 한양대학교 세라믹연구소 2018 Journal of Ceramic Processing Research Vol.19 No.4

The low temperature sol-gel approach is used in which the titanium butoxide (IV) precursor is hydrolyzed in the presence ofacetic and nitric acids to form a bidentate acetate complex (1538, 1429 cm−1 IR doublet). It is known that the role of the aceticacid as a chemical modifier controls the condensation and oligomerization reactions, but other effect of the complex acetateligand comprises the preferential crystallization of the titania into the anatase phase. In addition, it is found here, that thepresence of such a ligand at acidic pH values considerably impacts the nanostructure i.e. the formation of smooth hydrophobicanatase films containing fine non-aggregated nano-crystallites with auto-assembled micro pores. The resulting anatase-acetatenano-crystalline material is used to form thin films by the flow coating process. 4.2 nm size crystalline anatase and fullydispersed nanoparticles form a pattern of ultra-small crystallites as shown by TEM that are presumably responsible for theremarkable smooth and macro porous thin films with applications in photo-catalysis.

Rheology and gel point of the enzymatic hydrolysis of urea in the presence of urease

R. Serrato-Millán,L. Medina-Torres,F. Calderas,B.L. España-Sánchez,M. Estevez,A.R. Hernandez-Martínez,M. Cruz-Soto,I.C. Sánchez,R. Gómez-García,I. Sánchez-Betancourt,M.C. Velasquillo-Martínez,G. Luna- 한국유변학회 2017 Korea-Australia rheology journal Vol.29 No.1

This study reports on the rheology of the gelation kinetics of raw chitosan (CTS) solutions (2% w/v) produced by enzymatic hydrolysis of urea at different urea concentrations (40, 50, 60, 80, and 100 mM) in the presence of urease at 1 U/mL. Viscoelastic parameters and pH values were evaluated during gelation process and the rheological properties of CTS hydrogels produced were monitored after 24 h at 37°C to simulate human body temperatures. pH measurements suggest that above some critical urea concentration (50 mM) the time required (tgel) to reach the critical pH gelation shows no dependence on urea concentration (tgel was ca. 70 minutes). Above 50 mM of urea concentration, CTS hydrogels exhibit an elastic modulus G' higher than the viscous modulus G'' with no frequency dependence characteristic of a gel behavior. Gelation kinetics analyzed by rheology suggest that the G' (i.e., structure) development depends on urea concentration during solution neutralization.

Vedolizumab does not increase perioperative surgical complications in patients with inflammatory bowel disease, cohort study

( Vitaliy Y. Poylin ),( Jose Cataneo Serrato ),( Jonathan Pastrana Del Valle ),( Joseph D. Feuerstein ) 대한장연구학회 2022 Intestinal Research Vol.20 No.1

Background/Aims: Biologics are increasingly used to manage ulcerative colitis (UC) and Crohn’s disease (CD). However, even with earlier usage of biologic therapy, a significant proportion of patients will require surgery. Vedolizumab is an anti-integrin antibody that is increasingly used given that it is more gut selective and associated with fewer side effects. The aim of this study is to assess the effect of vedolizumab compared to anti-tumor necrosis factor (anti-TNF) therapy on the perioperative complications in patients undergoing surgery for inflammatory bowel disease (IBD). Methods: Retrospective review of patients treated for IBD at a tertiary care center between 2013 and 2017. Rates of 30- and 90-day complications for patients on vedolizumab were compared to patients on anti-TNF regimens. Results: One hundred and ninety-nine patients met inclusion criteria with 87 (43%) patients undergoing surgery for CD, 111 (55.8%) for UC and 1 (0.5%) for indeterminate colitis. Thirty-eight patients received preoperative vedolizumab and 94 received anti-TNF. There were more males and lower body mass index in the anti-TNF group. There was no significant difference in overall rate of complications at 30 or 90 days. There was a trend for lower leak rate vedolizumab group (0% for vedolizumab vs. 2.1% for anti-TNF at 30 days, P=1.00; 0% for vedolizumab vs. 1.1% for anti-TNF at 90 days, P=1.00). Multivariate analysis showed low albumin (<3.6 g/dL) at the time of surgery to be a significant risk factor for overall and infectious complications at 90 days (odds ratio, 3.24; 95% confidence interval, 1.12-8.79; P=0.021). Conclusions: Perioperative vedolizumab does not increase rates of perioperative complications in IBD surgery when compared to anti-TNF medications. (Intest Res 2022;20:72-77)

Determination of the activation energy for densification of porcelain stoneware

Simón Yobanny Reyes López,Juan Serrato Rodríguez,Satoshi Sugita Sueyoshi 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.3

Experimental porcelain stoneware has been formed by slip casting and sintered by rate controlled dilatometry. Shrinkage has been measured at various constant heating rates up to 1300 oC by dilatometry. A kinetic field for stoneware firing has been set up by connecting points of equal density on the sintering rate curves to determine the activation energy for densification and to calculate optimum firing cycles. The activation energy for densification has been calculated from the slope of the isodensity curves. It has been observed that the activation energy increases with progressive sintering i.e. 470-497 kJ/mol for the intermediate sintering stage (1100-1225 oC) accounting for most of the densification. The abrupt shrinkage and low activation energy values during the intermediate sintering stage suggest a viscous flow mechanism of densification. The final sintering stage responsible for a reduced densification rate showed a lower 313 kJ/mol activation energy.

Microstructural characterization of sanitaryware by infrared and Raman spectroscopy, the role of vitreous matrix on propierties

Simón Yobanny Reyes López,Juan Serrato Rodríguez 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.1

Besides Raman and infrared spectroscopy, DSC/DTA/TGA, dilatometry, XRD, and SEM techniques were used to characterize phase transitions and microstructural evolution in porcelain stoneware. An experimental porcelain composition has been formed by slip casting and sintered in an electric furnace. Thermal evolution of raw materials shows dehydroxylation of kaolinite, transformation to spinel and mullite, and transformation of α-quartz into β-quartz evidenced by Raman spectroscopy. Spinel and granular (primary) mullite is seen to form in clay relicts which may subsequently become seeds for topotactic grown of acicular reinforcing mullite. As vitrification progresses the bridging silicon oxygen varies and can lead to connectivity changes in the silica network. The development of glassy matrix was followed by infrared spectroscopy at the porcelain intermediate sintering stage. Si-O-Si bands at 780 and 1070 cm−1 for symmetric and asymmetric stretching vibrations in the spectra have been analyzed using a polymerization index (PI). PI indicates the degree of depolymerization of the vitreous matrix through densification. PI was found to correlate well with thermal expansion, bulk density and Young’s modulus. This correlation of glass structure and properties may suggest that changes in the IR spectra could be used to predict physical properties.

Microstructural characterization of sanitaryware, the relationship spinel and mullite

Simón Yobanny Reyes López,Juan Serrato Rodríguez,Satoshi Sugita Sueyoshi 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.4

Sanitaryware reference industrial experimental compositions have been formulated, formed by slip casting and subsequently sintered in a laboratory electric furnace. Microstructural evolution was followed by HRTEM, BSE, X-ray diffraction and infrared spectroscopy. Thermal evolution of raw materials shows dehydroxylation of kaolinite, transformation to spinel and mullite, and transformation of α-quartz into β-quartz. Principal discussions are focused on the spinel and mullite evolution in the 900-1300 ο C temperature range. Evidence of the phase trans formation from spinelto mullite were found in single crystals characterized locally by fast Fourier transformand lattice fringe d spacing accounting for the coexistence of nanometric mullite with the cubic spinel phase. Back scattered electrons (BSE) in topographic mode have been used to show the presence of the spinel type intergrowth plates within the sanitaryware microstructure. Aspect ratio calculations and interplanar analysis of the distances shows less characteristic planes of spinel as mullitization and vitrification progresses, mullite planes increase up to 1250 ο C and decrease at 1300 ο C.

Chemical Composition, In vitro Gas Production, Ruminal Fermentation and Degradation Patterns of Diets by Grazing Steers in Native Range of North Mexico

Murillo, M.,Herrera, E.,Carrete, F.O.,Ruiz, O.,Serrato, J.S. Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.10

The objective of the study was to quantify annual and seasonal differences in the chemical composition, in vitro gas production, in situ degradability and ruminal fermentation of grazing steers… diets. Diet samples were collected with four esophageal cannulated steers ($350{\pm}3$ kg BW); and four ruminally cannulated heifers ($342{\pm}1.5$ kg BW) were used to study the dry matter degradation and fermentation in rumen. Data were analyzed with repeated measurements split plot design. The crude protein, in vitro dry matter digestibility and metabolizable energy were higher during the first year of trial and in the summer (p<0.01). The values of calcium, phosphorus, magnesium, zinc and copper were higher in summer (p<0.05). The gas produced by the soluble and insoluble fractions, as well as the constant rate of gas production were greater in summer and fall (p<0.01). The ammonia nitrogen ($NH_3N$) and total volatile fatty acids concentrations in rumen, the soluble and degradable fractions, the constant rate of degradation and the effective degradability of DM and NDF were affected by year (p<0.05) and season (p<0.01). Our study provides new and useful knowledge for the formulation of protein, energetic and mineral supplements that grazing cattle need to improve their productive and reproductive performance.

Analysis of the phase transformation of aluminum formate Al(O2CH)3 to α-alumina by Raman and infrared spectroscopy

Simón Yobanny Reyes López,Rosa Saucedo Acuña,Rigoberto López-Juárez,Juan Serrato Rodríguez 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.5

A new simplified route to prepare crystalline α-alumina powders is proposed from the decomposition of aluminum formate Al(O2CH)3 precursor following a process of gelation of Al(O2CH)3 in an aqueous medium. Heat treated powders were characterized by XRD, Raman and infrared spectroscopy showing the presence of η-Al2O3 at 1000 o C and the transformation to α-Al2O3 at 1100 o C, where SEM images of α-Al2O3 reveled an size of 1-2 μm by the aggregated particles, and TEM images confirm a particles size of 200-300 nm. By other hand BET study showed that the specific surface area of η-Al2O3 and the α- Al2O3 obtained is higher than the specific surface area reported for these materials (until 118 m2 /g), ratify that this new route process at low temperature promote to obtain the powers with an excellent superficial area.

A novel antimicrobial-containing nanocellulose scaffold for regenerative endodontics

Kichler Victoria,Teixeira Lucas Soares,Prado Maick Meneguzzo,Colla Guilherme,Schuldt Daniela Peressoni Vieira,Coelho Beatriz Serrato,Porto Luismar Marques,de Almeida Josiane 대한치과보존학회 2021 Restorative Dentistry & Endodontics Vol.46 No.2

Objectives: The aim of this study was to evaluate bacterial nanocellulose (BNC) membranes incorporated with antimicrobial agents regarding cytotoxicity in fibroblasts of the periodontal ligament (PDLF), antimicrobial activity, and inhibition of multispecies biofilm formation. Materials and Methods: The tested BNC membranes were BNC + 1% clindamycin (BNC/CLI); BNC + 0.12% chlorhexidine (BNC/CHX); BNC + nitric oxide (BNC/NO); and conventional BNC (BNC; control). After PDLF culture, the BNC membranes were positioned in the wells and maintained for 24 hours. Cell viability was then evaluated using the MTS calorimetric test. Antimicrobial activity against Enterococcus faecalis, Actinomyces naeslundii, and Streptococcus sanguinis (S. sanguinis) was evaluated using the agar diffusion test. To assess the antibiofilm activity, BNC membranes were exposed for 24 hours to the mixed culture. After sonicating the BNC membranes to remove the remaining biofilm and plating the suspension on agar, the number of colony-forming units (CFU)/mL was determined. Data were analyzed by 1-way analysis of variance and the Tukey, Kruskal-Wallis, and Dunn tests (α = 5%). Results: PDLF metabolic activity after contact with BNC/CHX, BNC/CLI, and BNC/NO was 35%, 61% and 97%, respectively, compared to BNC. BNC/NO showed biocompatibility similar to that of BNC (p = 0.78). BNC/CLI showed the largest inhibition halos, and was superior to the other BNC membranes against S. sanguinis (p < 0.05). The experimental BNC membranes inhibited biofilm formation, with about a 3-fold log CFU reduction compared to BNC (p < 0.05). Conclusions: BNC/NO showed excellent biocompatibility and inhibited multispecies biofilm formation, similarly to BNC/CLI and BNC/CHX.