Spectral Lines
Mostrando 1-12 de 93 artigos, teses e dissertações.
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1. Friedelane Triterpenes with Cytotoxic Activity from the Leaves of Maytenus quadrangulata (Celastraceae)
Three new triterpenes, 3,4-seco-3,11β-epoxyfriedel-4(23)-en-3β-ol (1), friedelan-3α,11β diol (2), 7β,26-epoxyfriedelan-3a,7a-diol (3), a mixture of two new triterpenes 3α-hydroxyfriedelan-29-yl palmitate (4) and 3α-hydroxyfriedelan-29-yl stearate (5) and eleven known compounds were obtained from the hexane extract of Maytenus quadrangulata leaves. The
Journal of the Brazilian Chemical Society. Publicado em: 2022
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2. Determination of carrageenan in jellies with new methylene blue dye using spectrophotometry, smartphone-based colorimetry and spectrophotometric titration
Abstract Carrageenan is a seaweed polysaccharide widely used as a food gelling and thickening agent. The New Methylene Blue dye was tested as an analytical reagent for the quantification of carrageenan in commercial jelly samples. The main spectral peaks of the dye decrease with increasing carrageenan-to-dye molar ratio up to 1. Three analytical procedures w
Food Sci. Technol. Publicado em: 2021-06
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3. Combination of Multi-Energy Calibration (MEC) and Laser-Induced Breakdown Spectroscopy (LIBS) for Dietary Supplements Analysis and Determination of Ca, Mg and K
This study describes the application of laser-induced breakdown spectroscopy (LIBS) for the direct determination of Ca, K and Mg in powdered dietary supplements. Multi-energy calibration (MEC) method was applied to obtain a calibration curve. With MEC, it was possible to observe spectral interferences and select adequate emission lines from LIBS. For Ca and
J. Braz. Chem. Soc.. Publicado em: 2019-04
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4. Physiochemical and Optical Properties of GdF3:Pr@LaF3@SiO2 Microspheres
The polyol-based co-precipitation process was employed for synthesis of GdF3:Pr (core) and GdF3:Pr@LaF3 (core-shell) microspheres (MSs). Subsequently, an amorphous silica layer was deposited surrounding the core-shell MSs, which was verified from high-resolution transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and FTIR results.
Mat. Res.. Publicado em: 12/04/2018
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5. Leishmanicidal compounds of Nectria pseudotrichia, an endophytic fungus isolated from the plant Caesalpinia echinata (Brazilwood)
BACKGROUND In a screen of extracts from plants and fungi to detect antileishmanial activity, we found that the ethyl acetate extract of the fungus Nectria pseudotrichia, isolated from the tree Caesalpinia echinata (Brazilwood), is a promising source of bioactive compounds. OBJECTIVES The aims of this study were to isolate and determine the chemical structu
Mem. Inst. Oswaldo Cruz. Publicado em: 2018-02
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6. UTILIZAÇÃO DO ESPECTRÔMETRO DE ABSORÇÃO ATÔMICA PARA DETERMINAÇÃO DE CLORIDRATO DE METFORMINA E CLORIDRATO DE RANITIDINA EM MEDICAMENTOS
The utilization of atomic absorption spectrometer for metformin (MET) and ranitidine (RAN) chlorohydrates determination in medicines is proposed. The spectral lines of nickel and aluminum at 232.0 and 308.2 nm were selected for MET and RAN absorbance monitoring, respectively. The results were compared to those obtained by molecular absorption spectrometry at
Quím. Nova. Publicado em: 2017-10
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7. Antiproliferative Activity of Dibenzoylmethanes from Root Bark of Muellera filipes (Benth) M.J. Silva & A.M.G. Azevedo
Three new dibenzoylmethane derivatives, (E)-3,4-methylenedioxy-2'-methoxy-2'',2''-dimethylpyrano-(5'',6'':3',4')-7-methoxychalcone, 2'-hydroxy-5'(3'''',3''''-dimethylallyl)-8-(α,α-dimethylallyl)-furano-(4'',5'':3'4')-dibenzoylmethane and 2'-O-(3'',3''-dimethylallyl)-8-(α,α-dimethylallyl)-furano-(4'',5'':3'4')-dibenzoylmethane, were isolated from a dichlo
J. Braz. Chem. Soc.. Publicado em: 2017-08
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8. Microwave Assisted Synthesis of Novel Six-Membered 4-C, 4-O and 4-S Lactams Derivatives: Characterization and in vitro Biological Evaluation of Cytotoxicity and Anticoagulant Activity
A series of six-membered lactam derivatives containing C, O and S atoms in position 4 were synthesized using microwave methodology through coupling reactions. The novel compounds were synthesized following two step reaction to yield fifteen derivatives. The final derivative N-(4-(3-oxotiomorpholin)phenyl) hexanamide was selectively toxic to the HCT-116 cell
J. Braz. Chem. Soc.. Publicado em: 2017-02
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9. Cucumol A: a cytotoxic triterpenoid from Cucumis melo seeds
ABSTRACT Phytochemical investigation of the MeOH extract of Cucumis melo L. var. reticulates, Cucurbitaceae, seeds led to the isolation of a new triterpenoid: cucumol A (27-hydroxy taraxerol-3β-ol), along with three known compounds: α-spinasterol and D:B-friedoolean-5-ene-3-β-ol. Their structures were established by extensive 1D (1H, 13C, and DEPT) and 2D
Rev. bras. farmacogn.. Publicado em: 2016-12
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10. Bioassay guided purification of cytotoxic natural products from a red alga Dichotomaria obtusata
ABSTRACT Different solvent extracts of Dichotomaria obtusata (J. Ellis & Solander) Lamark, Galaxauraceae, a red algae collected from the coast of Bushehr in the Persain Gulf, was investigated for its cytotoxic properties and chemical constituents. The fresh alga, after extraction with methanol and dichloromethane were combined and partitioned between water,
Rev. bras. farmacogn.. Publicado em: 2016-12
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11. Chemical Profile and Cytotoxic Activity of Leaf Extracts from Senna spp. from Northeast of Brazil
Methanolic, diethyl ether and n-hexane extracts of leaves of four species of Senna (S. gardneri, S. macranthera, S. splendida and S. trachypus) were analyzed by gas chromatography coupled to mass spectrometry (GC-MS). Using linear retention indices and mass spectral data, 34 compounds were identified, including fatty acids, flavonoids, terpenoids and steroid
J. Braz. Chem. Soc.. Publicado em: 2016-10
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12. Early Structural Damage Assessment by Using an Improved Frequency Evaluation Algorithm
Abstract This paper introduces a method to identify damages in beam-like structures by analyzing the natural frequency changes of the first six transversal vibration modes. A correlation between the damage location and frequency change is established for each mode separately, by considering the modal strain energy stored in that location. The mathematical re
Lat. Am. j. solids struct.. Publicado em: 2015-12