Search

Your search keyword '"Neng, Nuno"' showing total 245 results
Start Over Author "Neng, Nuno"
245 results on '"Neng, Nuno"'

2. Continuum model for extraction and retention in porous media

Author

Matias, André F. V., Valente-Matias, Daniel F., Neng, Nuno R., Nogueira, José M. F., Andrade Jr., José S., Coelho, Rodrigo C. V., and Araújo, Nuno A. M.

Subjects
Physics - Fluid Dynamics, Condensed Matter - Soft Condensed Matter
Abstract

Several natural and industrial processes involve the extraction or retention of a solute by a fluid invading a network of channels. Examples include aquifer contamination, chemical filtration, and coffee extraction. We propose a continuum equation to model these processes, parametrized by the P\'eclet number and the rate of mass transfer between the solid and the fluid. We study the time dependence of the extracted mass for different values of the parameter space. The continuum description is validated by combining extraction experiments with coffee and computational fluid dynamics. An analytical solution is derived for the limit of slow mass transfer, which is corroborated by numerical simulations.

Published
2023
Full Text
View/download PDF

6. Bar Adsorptive Microextraction Approach for Trace Determination of Local Anesthetics in Urine Matrices.

Author

Pereira, Joana R. P., Rocha, Daniela C., Neng, Nuno R., Maurício, Paulo, Torres, M. Edite, Ahmad, Samir M., and Quintas, Alexandre

Subjects
GAS chromatography/Mass spectrometry (GC-MS), COMPLEX matrices, LOCAL anesthetics, EXTRACTION techniques, PROCAINE
Abstract

The present work reports the development, optimization, and validation, of a methodology to determine lidocaine, procaine, tetracaine, and benzocaine in urine matrices. Two extractive preconcentration techniques, solid-phase microextraction (SPME) LC Tips and bar adsorptive microextraction (BAμE), were studied and applied to the four target anesthetics, followed by gas chromatography-mass spectrometry (GC-MS) analysis. Several parameters that could affect microextraction and back-extraction were optimized using two different designs of experiments (Box–Behnken and full-factorial) to maximize extraction efficiency from aqueous media. Under optimized experimental conditions, the BAμE technique showed better performance than SPME LC Tips and was chosen for validation assays and urine sample analysis. In blank urine, the BAµE/GC-MS methodology revealed suitable sensitivity (LOD between 2 and 18 ng/mL), good linearity (r2 ≥ 0.9945) between 0.5 and 30.0 µg/mL and recovery yields of 30.3–97.9%. Good precision (%RSD ≤ 8.8%) and accuracy (bias % between −15.9 and 15.0%) values were achieved. The developed methodology was successfully applied to the target anesthetics analysis of volunteers' urine matrices and proved to be an environmentally friendly alternative to monitor trace levels of local anesthetics in complex matrices compared to other extraction techniques. [ABSTRACT FROM AUTHOR]

Published
2025
Full Text
View/download PDF

14. Modern Sample Preparation Approaches for Separation Science

Author

Neng, Nuno

Abstract

This book will provide the most recent knowledge and advances in Sample Preparation Techniques for Separation Science. Everyone working in a laboratory must be familiar with the basis of these technologies, and they often involve elaborate and time-consuming procedures that can take up to 80% of the total analysis time. Sample preparation is an essential step in most of the analytical methods for environmental and biomedical analysis, since the target analytes are often not detected in their in-situ forms, or the results are distorted by interfering species. In the past decade, modern sample preparation techniques have aimed to comply with green analytical chemistry principles, leading to simplification, miniaturization, easy manipulation of the analytical devices, low costs, strong reduction or absence of toxic organic solvents, as well as low sample volume requirements.Modern Sample Preparation Approaches for Separation Science also provides an invaluable reference tool for analytical chemists in the chemical, biological, pharmaceutical, environmental, and forensic sciences.

Published
2019

17. Isololiolide, a carotenoid metabolite isolated from the brown alga Cystoseira tamariscifolia, is cytotoxic and able to induce apoptosis in hepatocarcinoma cells through caspase-3 activation, decreased Bcl-2 levels, increased p53 expression and PARP cleavage

Author

Vizetto-Duarte, Catarina, Custódio, Luísa, Gangadhar, Katkam N., Lago, João Henrique G., Dias, Catarina, Matos, Ana Marta, Neng, Nuno, Nogueira, José Manuel Florêncio, Barreira, Luísa, Albericio, Fernando, Rauter, Amelia P., and Varela, João

Published
2016
Full Text
View/download PDF

36. Wild vs cultivated halophytes: Nutritional and functional differences

Author

Castañeda-Loaiza, Viana, primary, Oliveira, Marta, additional, Santos, Tamára, additional, Schüler, Lisa, additional, Lima, Alexandre R., additional, Gama, Florinda, additional, Salazar, Miguel, additional, Neng, Nuno R., additional, Nogueira, J.M.F., additional, Varela, João, additional, and Barreira, Luísa, additional

Published
2020
Full Text
View/download PDF

39. In vitro enzyme inhibitory and anti-oxidant properties, cytotoxicity and chemical composition of the halophyte Malcolmia littorea (L.) R.Br. (Brassicaceae).

Author

Castañeda-Loaiza, Viana, Placines, Chloé, Rodrigues, Maria João, Pereira, Catarina G., Zengin, Gokhan, Neng, Nuno R., Nogueira, José M. F., and Custódio, Luísa

Subjects
AMYLASES, PHENOL oxidase, BRASSICACEAE, SALICYLIC acid, PHENOLIC acids, HALOPHYTES
Abstract

This work reports for the first time the in vitro anti-oxidant (towards DPPH, ABTS, copper and iron), enzymatic inhibitory (on AChE, BuChE, α-glucosidase, α-amylase and tyrosinase), cytotoxicity (towards HepG2 and HEK 293 cells), and metabolomics (by HPLC-MS) of extracts from organs of Malcolmia littorea (L.) R.Br. Extracts were constituted mainly by phenolic acids and flavonoids, and main compounds were salicylic acid and luteolin-7-O-glucoside. Samples showed reduced radical scavenging and metal chelating capacity, and only the methanol extracts reduced iron. The root's ethanol and methanol extracts, and the aerial organ's ethanol extract exhibited the highest AChE inhibition. The root's ethanol extract displayed dual anti-cholinesterase activity. Samples showed a low capacity to inhibit α-amylase, but a high α-glucosidase inhibition was obtained with the root's and flower's ethanol extracts, and flower's methanol extract. Overall, samples displayed a high inhibition against tyrosinase, reduced HepG2 cellular viability and were less toxic towards HEK 293 cells. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

45. First report of the in vitro antileishmanial properties of extremophile plants from the Algarve Coast

Author

Oliveira, Marta, primary, João Rodrigues, Maria, additional, Pereira, Catarina, additional, Neto, Rubens Lima do Monte, additional, Junior, Policarpo Ademar Santos, additional, Neng, Nuno da Rosa, additional, Nogueira, José Manuel Florêncio, additional, Varela, João, additional, Barreira, Luísa, additional, and Custódio, Luísa, additional

Published
2017
Full Text
View/download PDF

47. An Overview on the Properties of Ximenia Oil Used as Cosmetic in Angola.

Author

Satoto, Gabriel, Fernandes, Ana Sofia, Saraiva, Nuno, Santos, Fernando, Neng, Nuno, Nogueira, José Manuel, de Almeida, Tânia Santos, and Araujo, Maria Eduarda

Subjects
HAIR conditioners, SKIN temperature, OILSEEDS, FATTY acids
Abstract

Ximenia (Ximenia americana L.) is a shrub, or small tree, native from Africa and spread across different continents. In Angola, the seeds oil is used by local populations, to prevent sunburn, to smooth and hydrate the skin, and to give it a pleasant color and elasticity, to prevent stretch marks, in pregnant woman, and also as hair conditioner. Herein, an oil sold in the region (LPO), and two others extracted in laboratory, from seeds collected in the same region, were investigated in terms of their composition, chemical properties, UV transmission. The three oils are similar although the LPO is more acidic, 0.48 mg KOH/g. GC-MS analysis indicated that the major components are the fatty acids, oleic (31.82%), nervonic (11.09%), ximenic (10.22%), and hexacosa-17,20,23-trienoic acids (14.59%). Long chain fatty acids, n ≥ 20, accounted for 51.1% of the total fatty acids. A thin film of the oil showed a reduction in transmittance from 200 to 300 nm. Viscosity studies of the LPO indicated that at normal temperature of skin, the oil can be spread over the skin as a thin film. At concentrations up to 10 µg/mL, the LPO is not toxic to human keratinocytes, suggesting the safety of this oil. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

48. In vitro antioxidant and inhibitory activity of water decoctions of carob tree (Ceratonia siliqua L.) on cholinesterases, α-amylase and α-glucosidase

Author

Custódio, Luísa, Patarra, João, Alberício, Fernando, Neng, Nuno Rosa, Nogueira, José Manuel Florêncio, and Romano, Anabela

Subjects
complex mixtures
Abstract

This work reports the in vitro inhibitory activity of water decoctions of leaves, germ flour, pulp, locust bean gum and stem bark of carob tree on α-amylase, α-glucosidase, acetylcholinesterase and butyrylcholinesterase. The antioxidant activity and the chemical characterisation of the extracts made by spectrophotometric assays and by high-performance liquid chromatography are also reported. Leaves and stem bark decoctions strongly inhibited all the enzymes tested, had significant antioxidant activity and the highest total phenolics content. The major compounds were identified as gallic acid in the leaves and gentisic acid in the stem bark.

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results