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91.
Spectrophotometric data followed by a suitable treatment of chemometric analysis were used for the simultaneous determination of monosodium glutamate (MSG), guanosine 5′-monophosphate (GMP) and inosine 5′-monophosphate (IMP) in stock cube samples, without any previous extraction step. By this way, the overlapping of the absorption spectra was resolved using a PLS-1 model. The concentration for experimental calibration matrix were varied between 5.03–34.2 μg mL−1 for IMP and GMP, and 448–1399 μg mL−1 for MSG. The relative errors of prediction (REPCV %) were 1.8, 2.8 and 3.1 for IMP, GMP and MSG, respectively. 相似文献
92.
Renato M. Cotta Bianca P. Cotta Carolina P. Naveira-Cotta Gerson Cotta-Pereira 《International Journal of Thermal Sciences》2010,49(9):1510-1516
Pennes’ equation is the most frequently employed model to describe heat transfer processes within living tissues, with numerous applications in clinical diagnostics and thermal treatments. A number of analytical solutions were provided in the literature that represent the temperature distribution across tissue structures, but considering simplifying assumptions such as uniform and linear thermophysical properties and blood perfusion rates. The present work thus advances such analysis path by considering a heterogeneous medium formulation that allows for spatially variable parameters across the tissue thickness. Besides, the eventual variation of blood perfusion rates with temperature is also accounted for in the proposed model. The Generalized Integral Transform Technique (GITT) is employed to yield a hybrid numerical–analytical solution of the bioheat model in heterogeneous media, which reduces to the exact solution obtained via the Classical Integral Transform Method for a linear formulation with uniform coefficients. The open source UNIT code (“UNified Integral Transforms”) is utilized to obtain numerical results for a set of typical values of the governing parameters, in order to illustrate the convergence behavior of the proposed eigenfunction expansions and inspect the importance of accounting for spatially variable properties in predicting the thermal response of living tissues to external stimulus. 相似文献
93.
Rita X. Valenzuela Gema Bueno Vicente Cort s Corber n Yide Xu Changlin Chen 《Catalysis Today》2000,61(1-4):43-48
Ceria catalysts were found active and selective to the oxidehydrogenation of ethane (ODE) with CO2 and the actual contribution for C2H4 formation from heterogeneous catalysis was 75–55% in the range 953–993 K. The presence of calcium ions in solid solution in the ceria crystalline network increased significatively the selectivity to ethene and the efficiency of CO2 as oxidant in the heterogeneous reaction. 相似文献
94.
The performance of V–Ca–O catalysts for the oxidative dehydrogenation of propane has been studied for the first time, being
compared with that of similar V–Mg–O catalysts, and their differences are interpreted in terms of their physico-chemical properties.
The VCaO catalyst showed the same initial selectivity to propene as the most selective VMgO composition, but it decreased
faster with increasing propane conversion. Vanadium species present in the catalyst surface were different for the two supports:
isolated V5+ tetrahedra on CaO and magnesium orthovanadate and pyrovanadate on MgO. The intrinsic activity of isolated vanadium centres
in the surface of the V–Ca–O catalyst was more than one order of magnitude higher than that of dimeric or polymeric tetahedral
species in the magnesium-containing catalysts.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
95.
Today, in addition to traditional mobile services, there are new ones already being used, thanks to the advances in 3G-related technologies. Our work contributed to the emerging body of research by integrating TAM and Diffusion Theory. Based on a sample of 542 Dutch consumers, we found that traditional antecedents of behavioral intention, ease of use and perceived usefulness, can be linked to diffusion-related variables, such as social influence and perceived benefits (flexibility and status). 相似文献
96.
Mauricio Osorio Marcela Carvajal Alejandra Vergara Estefania Butassi Susana Zacchino Carolina Mascayano Margarita Montoya Sophia Mejías Marcelo Cortez-San Martín Yesseny Vsquez-Martínez 《International journal of molecular sciences》2021,22(11)
Prenylated flavonoids are an important class of naturally occurring flavonoids with important biological activity, but their low abundance in nature limits their application in medicines. Here, we showed the hemisynthesis and the determination of various biological activities of seven prenylated flavonoids, named 7–13, with an emphasis on antimicrobial ones. Compounds 9, 11, and 12 showed inhibitory activity against human pathogenic fungi. Compounds 11, 12 (flavanones) and 13 (isoflavone) were the most active against clinical isolated Staphylococcus aureus MRSA, showing that structural requirements as prenylation at position C-6 or C-8 and OH at positions C-5, 7, and 4′ are key to the antibacterial activity. The combination of 11 or 12 with commercial antibiotics synergistically enhanced the antibacterial activity of vancomycin, ciprofloxacin, and methicillin in a factor of 10 to 100 times against drug-resistant bacteria. Compound 11 combined with ciprofloxacin was able to decrease the levels of ROS generated by ciprofloxacin. According to docking results of S enantiomer of 11 with ATP-binding cassette transporter showed the most favorable binding energy; however, more studies are needed to support this result. 相似文献
97.
Continuous laboratory solvent extraction of gold from cyanide solutions has been investigated by using LIX 79 guanidine‐based extractant. Different variables that affected the extraction included aqueous pH, extractant concentration and modifier concentration. Extraction isotherms of the aurocyanide complex with respect to the other cyanoanions were compared, and the following order of selectivity was observed: Au > Ag > Cu > Zn > Fe. According to the pH isotherms, aurocyanide can be extracted in alkaline media, and a better separation with respect to other cyano anions was obtained in the pH range 10.5–11.2. From the McCabe‐Thiele diagrams, better recovery was observed when using LIX 79 and tridecanol at 10 vol.‐%. Stripping gold from the loaded organic was carried out at pH > 12 by using NaOH and NaCN solutions. The pilot plant tests indicate that a two‐stage extraction followed by one strip step are more than adequate to obtain an overall process efficiency of 92 %. However, for those cases where copper is present significantly, a copper wash stage is recommended before gold stripping. In this case, stripping of copper is accomplished at a pH 10.8, whereas the gold stripping was done at a pH of 12.0. 相似文献
98.
Ricardo I. Castro Ana Gonzlez-Feliu Marcelo Muoz-Vera Felipe Valenzuela-Riffo Carolina Parra-Palma Luis Morales-Quintana 《International journal of molecular sciences》2021,22(12)
The role of auxin in the fruit-ripening process during the early developmental stages of commercial strawberry fruits (Fragaria x ananassa) has been previously described, with auxin production occurring in achenes and moving to the receptacle. Additionally, fruit softening is a consequence of the depolymerization and solubilization of cell wall components produced by the action of a group of proteins and enzymes. The aim of this study was to compare the effect of exogenous auxin treatment on the physiological properties of the cell wall-associated polysaccharide contents of strawberry fruits. We combined thermogravimetric (TG) analysis with analyses of the mRNA abundance, enzymatic activity, and physiological characteristics related to the cell wall. The samples did not show a change in fruit firmness at 48 h post-treatment; by contrast, we showed changes in the cell wall stability based on TG and differential thermogravimetric (DTG) analysis curves. Less degradation of the cell wall polymers was observed after auxin treatment at 48 h post-treatment. The results of our study indicate that auxin treatment delays the cell wall disassembly process in strawberries. 相似文献
99.
Rachel Anne P. Valenzuela Scott R. Suter Alexi A. Ball‐Jones Dr. José M. Ibarra‐Soza Yuxuan Zheng Prof. Dr. Peter A. Beal 《Chembiochem : a European journal of chemical biology》2015,16(2):262-267
Immune stimulation triggered by siRNAs is one of the major challenges in the development of safe RNAi‐based therapeutics. Within an immunostimulatory siRNA sequence, this hurdle is commonly addressed by using ribose modifications (e.g., 2′‐OMe or 2′‐F), which results in decreased cytokine production. However, as immune stimulation by siRNAs is a sequence‐dependent phenomenon, recognition of the nucleobases by the trigger receptor(s) is also likely. Here, we use the recently published crystal structures of Toll‐like receptor 8 (TLR8) bound to small‐molecule agonists to generate computational models for ribonucleotide binding by this immune receptor. Our modeling suggested that modification of either the Watson–Crick or Hoogsteen face of adenosine would disrupt nucleotide/TLR8 interactions. We employed chemical synthesis to alter either the Watson–Crick or Hoogsteen face of adenosine and evaluated the effect of these modifications in an siRNA guide strand by measuring the immunostimulatory and RNA interference properties. For the siRNA guide strand tested, we found that modifying the Watson–Crick face is generally more effective at blocking TNFα production in human peripheral blood mononuclear cells (PBMCs) than modification at the Hoogsteen edge. We also observed that modifications near the 5′‐end were more effective at blocking cytokine production than those placed at the 3′‐end. This work advances our understanding of how chemical modifications can be used to optimize siRNA performance. 相似文献
100.
Changes in actin and tubulin expression in osteogenic cells cultured on bioactive glass‐based surfaces
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Carolina Scanavez Martins Emanuela Prado Ferraz Larissa Moreira Spinola De Castro‐Raucci Lucas Novaes Teixeira William Marcatti Amarú Maximiano Adalberto Luiz Rosa Paulo Tambasco De Oliveira 《Microscopy research and technique》2015,78(11):1046-1053
The present study evaluated whether the changes in the labeling pattern of cytoskeletal proteins in osteogenic cells cultured on bioactive glass‐based materials are due to altered mRNA and protein levels. Primary rat‐derived osteogenic cells were plated on Bioglass® 45S5, Biosilicate®, and borosilicate (bioinert control). The following parameters were assayed: (i) qualitative epifluorescence analysis of actin and tubulin; (ii) quantitative mRNA and protein expression for actin and tubulin by real‐time PCR and ELISA, respectively, and (iii) qualitative analysis of cell morphology by scanning electron microscopy (SEM). At days 3 and 7, the cells grown on borosilicate showed typical actin and tubulin labeling patterns, whereas those on the bioactive materials showed roundish areas devoid of fluorescence signals. The cultures grown on bioactive materials showed significant changes in actin and tubulin mRNA expression that were not reflected in the corresponding protein levels. A positive correlation between the mRNA and protein as well as an association between epifluorescence imaging and quantitative data were only detected for the borosilicate. SEM imaging of the cultures on the bioactive surfaces revealed cells partly or totally coated with material aggregates, whose characteristics resembled the substrate topography. The culturing of osteogenic cells on Bioglass® 45S5 and Biosilicate® affect actin and tubulin mRNA expression but not the corresponding protein levels. Changes in the labeling pattern of these proteins should then be attributed, at least in part, to the presence of a physical barrier on the cell surface as a result of the material surface reactions, thus limiting fluorescence signals. Microsc. Res. Tech. 78:1046–1053, 2015. © 2015 Wiley Periodicals, Inc. 相似文献