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101.
A new cloud point extraction (CPE) method for ergotamine analysis using fluorimetric detection is described. Ergotamine from an aqueous solution was preconcentrated into a smaller surfactant-rich phase using nonionic surfactant polyoxyethylene(7.5)nonylphenylether (PONPE 7.5). Differently from the conventional CPE procedure in which the resulting surfactant-rich phase is diluted by a fluidificant before its analysis, in this method the fluorescence measurements were carried out directly onto the undiluted surfactant-rich phase. The high viscosity provided by the undiluted surfactant rich phase greatly improved the fluorescence emission of ergotamine, leading to a total enhancement factor of 1325. This spectral advantage plus the preconcentration factor achieved, contributed to the method sensitivity allowing the ergotamine determination at trace level concentration. Under optimal experimental conditions, a linear calibration curve was obtained from 3.81 × 10−7 to 1.10 μg mL−1, with detection and quantification limits of 0.11 and 0.38 pg mL−1, respectively. The accuracy and versatility of the present methodology were proved by analyzing ergotamine in real samples of different natures such as pharmaceuticals, urine and saliva. 相似文献
102.
In this paper we assess the efficacy of a laser system, emitting at 635 nm, in methylene blue–mediated photodynamic inactivation of Pseudomonas aeruginosa that contaminates wounds, using diffuse reflectance spectrometry. The spectral plots of the contaminated wounds were recorded before and after laser irradiation, and the refractive index and extinction coefficient were determined by Kramers-Kronig analysis of reflectance spectra. The changes in optical parameter values after the treatment were corroborated with bacterial counts determined by bacteriological examination. The results revealed that the combined treatment 635-nm laser–methylene blue is an efficient way to destroy the bacteria that contaminate the wounds. 相似文献
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Simona Sipos Elena-Alina Moac Ioana Zinuca Pavel tefana Avram Octavian Marius Creu Dorina Coricovac Roxana-Marcela Racoviceanu Roxana Ghiulai Ramona Daniela Pan Codrua Marinela oica Florin Borcan Cristina Adriana Dehelean Zorin Criniceanu 《Molecules (Basel, Switzerland)》2021,26(8)
Melissa officinalis (MO) is a medicinal plant well-known for its multiple pharmacological effects, including anti-inflammatory, anticancer and beneficial effects on skin recovery. In this context, the present study was aimed to investigate the in vitro and in vivo safety profile of an MO aqueous extract by assessing cell viability on normal (HaCaT—human keratinocytes) and tumor (A375—human melanoma) cells and its impact on physiological skin parameters by a non-invasive method. In addition, the antioxidant activity and the antiangiogenic potential of the extract were verified. A selective cytotoxic effect was noted in A375 cells, while no toxicity was noticed in healthy cells. The MO aqueous extract safety profile after topical application was investigated on SKH-1 mice, and an enhanced skin hydration and decreased erythema and transepidermal water loss levels were observed. The in ovo CAM assay, performed to investigate the potential modulating effect on the angiogenesis process and the blood vessels impact, indicated that at concentrations of 100 and 500 µg/mL, MO aqueous extract induced a reduction of thin capillaries. No signs of vascular toxicity were recorded at concentrations as high as 1000 μg/mL. The aqueous extract of MO leaves can be considered a promising candidate for skin disorders with impaired physiological skin parameters. 相似文献
105.
Cédric Balan Roxana Pop Virginie Comte Didier Poinsot Virginie Ratovelomanana‐Vidal Pierre Le Gendre 《应用有机金属化学》2014,28(7):517-522
The influence of hydrogen pressure on the hydrosilylation of ketones catalyzed by [((S)‐SYNPHOS)Rh(nbd)]OTf has been studied. We have notably demonstrated that hydrogen significantly affected the outcome of the reaction while not being consumed as stoichiometric reducing agent. In THF, diethyl ether or toluene, the hydrogen pressure exceedingly accelerated the hydrosilylation reaction and preserved or even improved the enantioselectivity of the process. In CH2Cl2, the rhodium catalyst also showed generally higher catalytic activity under hydrogen pressure. Most serendipitously, several ketones were found to give products of absolute opposite configuration upon performing the hydrosilylation under argon atmosphere or under hydrogen pressure. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Carlos Cevallos-Morillo Pablo Cisneros-Prez Roxana Llive Marvin Ricaurte Carlos Reinoso Miguel Angel Meneses Maria del Cisne Guamn Alex Palma-Cando 《Molecules (Basel, Switzerland)》2021,26(24)
Croton lechleri, commonly known as Dragon’s blood, is a tree cultivated in the northwest Amazon rainforest of Ecuador and Peru. This tree produces a deep red latex which is composed of different natural products such as phenolic compounds, alkaloids, and others. The chemical structures of these natural products found in C. lechleri latex are promising corrosion inhibitors of admiralty brass (AB), due to the number of heteroatoms and π structures. In this work, three different extracts of C. lechleri latex were obtained, characterized phytochemically, and employed as novel green corrosion inhibitors of AB. The corrosion inhibition efficiency (IE%) was determined in an aqueous 0.5 M HCl solution by potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopy, measuring current density and charge transfer resistance, respectively. In addition, surface characterization of AB was performed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy techniques. Chloroform alkaloid-rich extracts resulted in IE% of 57% at 50 ppm, attributed to the formation of a layer of organic compounds on the AB surface that hindered the dezincification process. The formulation of corrosion inhibitors from C. lechleri latex allows for the valorization of non-edible natural sources and the diversification of the offer of green corrosion inhibitors for the chemical treatment of heat exchangers. 相似文献
108.
Isabel Costa Carla Alexandra Gouveia Félix Carvalho Roxana Falcão Moreira Ricardo Jorge Dinis‐Oliveira 《Biomedical chromatography : BMC》2013,27(8):1003-1011
Over recent years, hair has become the ideal matrix for retrospective investigation of chronic abuse, including for tramadol. However, in order to exclude the possibility of external contamination, it is also important to quantify simultaneously its main metabolite, O‐desmethyltramadol (M1), which presence in hair reflects systemic exposure. In the present study a methodology aimed at the simultaneous quantification of tramadol and M1 in human hair was developed and validated for the first time. After decontamination of hair samples (60 mg), tramadol and M1 were extracted with methanol in an ultrasonic bath (~5 h). Purification was performed by solid‐phase extraction using mixed‐mode extraction cartridges. Subsequently to derivatization, analysis was performed by gas chromatography–electron impact/mass spectrometry (GC‐EI/MS). The method proved to be selective. The regression analysis for both analytes was shown to be linear in the range of 0.1–20.0 ng/mg with correlation coefficients of 0.9995 and 0.9997 for tramadol and M1, respectively. The coefficients of variation oscillated between 3.85 and 13.24%. The limits of detection were 0.03 and 0.02 ng/mg, and the lower limits of quantification were 0.08 and 0.06 ng/mg for tramadol and M1, respectively. The proof of applicability was performed in hair samples from six patients undergoing tramadol therapy. All samples were positive for tramadol and M1. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
109.
Roxana Bujack Gerik Scheuermann Eckhard Hitzer 《Advances in Applied Clifford Algebras》2013,23(1):15-38
The large variety of Fourier transforms in geometric algebras inspired the straight forward definition of “A General Geometric Fourier Transform” in Bujack et al., Proc. of ICCA9, covering most versions in the literature. We showed which constraints are additionally necessary to obtain certain features like linearity, a scaling, or a shift theorem. In this paper we extend the former results by a convolution theorem. 相似文献
110.
Veronica P. Martino Roxana A. Ruseckaite A. Jiménez 《Journal of Thermal Analysis and Calorimetry》2006,86(3):707-712
In this work amorphous poly(L-lactide-co-D,L-lactide) (PLLA/PDLLA) was blended with four different
commercial adipates to obtain films with enhanced mechanical and thermal properties.
Efficiency of plasticizers was evaluated by studying their compatibility with
the polymer and their effect on its glass transition temperature. All plasticizers
were compatible with the matrix up to a critical composition depending on
its molar mass. The addition of plasticizers caused a decrease in elastic
modulus and tensile stress, meanwhile elongation at break had a maximum increase
for polyadipates with the lower molar mass. Monomeric adipate showed some
migration at concentration higher than 10 mass%, while the addition of the
higher molar mass plasticizer lead to eventual phase separation. Polyadipates
with low molar mass showed a promising behaviour to overcome the brittleness
in PLLA/PDLLA films. 相似文献