http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
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.
Yu Ling Lee-Tsai,Rodrigo Luna-Santiago,Roberta Demichelis-Gómez,Alfredo Ponce-de-León,Eric Ochoa-Hein,Karla María Tamez-Torres,María T Bourlon,Christianne Bourlon 대한혈액학회 2019 Blood Research Vol.54 No.2
BackgroundClostridium difficile infection (CDI) is a nosocomial condition prevalent in patients with hematological disorders. We aimed to identify the risk factors associated with the devel-opment of CDI and assess the mortality rate at 15 and 30 days among hematologic patients admitted to a tertiary care center.MethodsWe conducted a retrospective case-control study from January 2010 to December 2015. Forty-two patients with hematologic malignancy and CDI, and 84 with hematologic dis-ease and without history of CDI were included in the case and control groups, respectively.ResultsUnivariate analysis revealed that episodes of febrile neutropenia [odds ratio (OR), 5.5; 95% confidence interval (CI), 2.3‒12.9; P<0.001], admission to intensive care unit (OR, 3.8; 95% CI, 1.4‒10.2; P=0.009), gastrointestinal surgery (OR, 1.2; 95% CI, 1.1‒1.4; P<0.001), use of therapeutic (OR, 6.4; 95% CI, 2.5‒15.9; P<0.001) and prophylactic antibiotics (OR, 4.2; 95% CI, 1.6‒10.7; P=0.003) in the last 3 months, and >1 hospital-ization (OR, 5.6; 95% CI, 2.5‒12.6; P<0.001) were significant risk factors. Multivariate analysis showed that use of therapeutic antibiotics in the last 3 months (OR, 6.3; 95% CI, 2.1‒18.8; P=0.001) and >1 hospitalization (OR, 4.3; 95% CI, 1.7‒11.0; P=0.002) were independent risk factors. Three (7.1%) and 6 (14.2%) case patients died at 15 and 30 days, respectively.ConclusionThe risk factors for developing CDI were exposure to therapeutic antibiotics and previous hospitalization. Hematological patients who developed CDI had higher early mortality rates, suggesting that new approaches for prevention and treatment are needed.
Alejandro Hernández-Morales,Jackeline Lizzeta Arvizu-Gómez,Candy Carranza-Álvarez,Blanca Estela Gómez-Luna,Brenda Alvarado-Sánchez,Enrique Ramírez-Chávez,Jorge Molina-Torres 한국응용곤충학회 2015 Journal of Asia-Pacific Entomology Vol.18 No.2
Heliopsis longipes has been recognized as a potential source of insecticidal compounds called alkamides, which can be used to control populations of insect vector transmitters of several diseases that affect the human health. To determine the insecticidal activity of H. longipes against Anopheles albimanus and Aedes aegypti, crude extract of H. longipes roots and affininwere obtained. Catalytic reduction of affininwas performed to obtain two reduced amides, N-isobutil-2E-decenamide and N-isobutil-decanamide. Crude extract, affinin and its reduced amides were evaluated against third instar larvae of An. albimanus and Ae. aegypti. Results show that crude extract of H. longipes possess larvicidal activity against larval stage of An. albimanus and Ae. aegypti. This effect could be attributed to affinin, on which the conjugated double bonds present in the structure of the molecule are necessary to maintain larvicidal activity. This study demonstrated the potential of H. longipes to control larval stage of An. albimanus and Ae. aegypti, transmitter vectors of malaria and dengue fever, respectively.
de Luna, Mark Daniel G.,Wan, Meng-Wei,Golosinda, Lucille R.,Futalan, Cybelle M.,Lu, Ming-Chun ACS AMERICAN CHEMICAL SOCIETY 2017 ENERGY AND FUELS Vol.31 No.9
<P>Mixing-assisted oxidative desulfurization (MAOD) of model fuel that contains dibenzothiophene (DBT) using phosphotungstic acid (HPW) as a catalyst and hydrogen peroxide (H2O2) as an oxidant was evaluated. Characterization analysis of HPW shows that the average crystallite size is 82.39 nm, with a disintegrated structure and morphology. The effect of operating parameters, such as mixer speed (5000-10 000 rpm), tetraoctylammoniurn bromide [phase-transfer agent (PTA)]/HPW ratio (0.5:1-5:1), and temperature (25-60 degrees C), on the sulfur conversion of DBT was examined. Results show that the sulfur conversion increases with an increasing temperature and mixer speed and a lower amount of PTA. The highest sulfur removal and rate constant of 100.0% and 0.1528 min(-1), respectively, were attained under the following conditions: 1:1 ratio, 40 degrees C, and 10 000 rpm. The pseudo-first-order equation and Arrhenius equation were applied to determine the kinetic rate constant and activation energy of HPW in the oxidation of DBT in a MAOD system. High correlation coefficient values (R-2 >= 0.93) indicate that the pseudo-first-order equation has the goodness of fit in describing the experimental kinetic data. Moreover, the activation energy of HPW derived from the Arrhenius equation was 42.60 kJ/mol.</P>
de Luna, Mark Daniel G.,Futalan, Cybelle M.,Dayrit, Raymond A.,Choi, Angelo Earvin S.,Wan, Meng-Wei Elsevier 2018 Journal of Cleaner Production Vol.203 No.-
<P><B>Abstract</B></P> <P>In this study, oxidative-adsorptive desulfurization technology was applied to raw diesel containing 1480.4 ppm sulfur. For oxidative desulfurization, the oxidant and catalyst were hydrogen peroxide and phosphotungstic acid, respectively. Two types of continuously mixed reactors: (1) continuous stirred tank reactor (CSTR) and (2) in-line mixer were evaluated under varying reaction temperature, mixing speed and diesel flow rate. For the in-line mixer system, the mixer speed and the flow rates for diesel and oxidant were modeled and optimized using Box-Behnken design of the response surface methodology. Optimization of process parameters resulted in sulfur removal of 85.90% at 18,000 rpm mixer speed, 500 mL min<SUP>−1</SUP> diesel flow rate and 300 mL min<SUP>−1</SUP> H<SUB>2</SUB>O<SUB>2</SUB> flow rate. In the subsequent adsorptive desulfurization experiments, continuous fixed-bed adsorption using alumina removed 92.81% sulfur from treated diesel fuel thereby producing low-sulfur diesel that is within the allowable limit of Euro IV standard.</P> <P><B>Highlights</B></P> <P> <UL> <LI> In-line mixer has better removal efficiency of sulfur from diesel over CSTR. </LI> <LI> Oxidative-adsorptive desulfurization achieved 92.81% sulfur removal. </LI> <LI> Oxidative-adsorptive desulfurization achieved residual sulfur of 30 ppm. </LI> </UL> </P>
Stepped Propane Adsorption in Pure-Silica ITW Zeolite
Min, Jung Gi,Luna-Triguero, Azahara,Byun, Youngchul,Balestra, Salvador R. G.,Vicent-Luna, Jose Manuel,Calero, Sofia,Hong, Suk Bong,Camblor, Miguel A. American Chemical Society 2018 Langmuir Vol.34 No.16
<P>Gas adsorption over zeolites is at the basis of important applications of this class of microporous crystalline solids, notably as separation media and catalysts, but it may also be complex and not straightforward to understand. Here we report that for temperature below 323 K propane adsorption on the small-pore pure-silica zeolite ITW exhibits a clear step (pseudosaturation). This is absent in the case of propene and the other small linear alkanes. An intermediate plateau, clearly observed in the 293 K isotherm, always occurs when one molecule of propane is loaded in every other cage, i.e., at half-saturation. The simulation results show a swelling of the ITW structure upon propane adsorption. The strong dependence of available pore volume on the adsorbate loading level implies that adsorption cannot occur on the void structure while saturation can only be reached on highly loaded structures. To account for this unprecedented adsorption phenomenon, we propose the term “guest-modulated effect”.</P> [FIG OMISSION]</BR>
Heme Binding Biguanides Target Cytochrome P450-Dependent Cancer Cell Mitochondria
Guo, Z.,Sevrioukova, I.F.,Denisov, I.G.,Zhang, X.,Chiu, T.L.,Thomas, D.G.,Hanse, E.A.,Cuellar, R.A.D.,Grinkova, Y.V.,Langenfeld, V.W.,Swedien, D.S.,Stamschror, J.D.,Alvarez, J.,Luna, F.,Galvan, A.,Bae Elsevier 2017 Cell chemical biology Vol.24 No.10