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61.
Benevenuto CG Di Matteo MA Maia Campos PM Gaspar LR 《Photochemistry and photobiology》2010,86(6):1390-1396
Vitamin A palmitate has been used in cosmetics; however, studies report that this substance shows photoreactivity that can lead to loss of safety and efficacy. On the other hand, photostabilizers have been used to increase sunscreen photostability and consequently their safety and effectiveness. Thus, this study aimed to evaluate the influence of photostabilizers on the photoprotective effects of a cosmetic formulation containing UV-filters and vitamin A palmitate. The formulation containing UV-filters was supplemented with vitamin A palmitate and the photostabilizers diethylhexyl 2,6-naphthalate (DEHN), bumetrizole and benzotriazolyl dodecyl p-cresol (BTDC). Hairless mice were treated daily by topical applications and irradiated (UVA/B). Erythema index, transepidermal water loss, histological/histometric analysis and number of sunburn cells (SBC) were evaluated. The results showed that all formulations protected from UV-induced enhancement of erythema and SBC but there was no difference among them. The formulation with no stabilizers reduced viable epidermis thickness due to atrophy induced by UV radiation. Thus, it can be concluded that the presence of photostabilizers influenced the effects of formulations containing UV-filters and vitamin A palmitate, which could be seen by histological and histometric analysis. Furthermore, the formulations containing the stabilizers DEHN and BTDC showed better protective effects on hairless mice skin. 相似文献
62.
Aguiar JC Santiago GM Lavor PL Veras HN Ferreira YS Lima MA Arriaga AM Lemos TL Lima JQ de Jesus HC Alves PB Braz-Filho R 《Natural product communications》2010,5(12):1977-1980
The chemical compositions of the essential oils from the peel of ripe and unripe fruits of Hymenaea courbaril L., obtained by hydrodistillation, were analyzed by GC and GC-MS. The main constituents of the essential oil from the peel of the ripe fruits were the sesquiterpenes alpha-copaene (11.1%), spathulenol (10.1%) and beta-selinene (8.2%), while germacrene-D (31.9%), beta-caryophyllene (27.1%) and bicyclogermacrene (6.5%) were the major compounds in the oil from unripe fruits. The essential oils were tested against Aedes aegypti larvae and showed LC50 values of 14.8 +/- 0.4 microg/mL and 28.4 +/- 0.3 microg/mL for the ripe and unripe fruit peel oils, respectively. From the peel of the ripe fruits, the diterpenes zanzibaric acid and isoozic acid were isolated, along with the sesquiterpene caryolane-1,9beta-diol. To the best of our knowledge, this is the first report of this sesquiterpene in the genus. The structures of all compounds isolated were identified on the basis of their spectral data (IR, MS, 1D- and 2D-NMR) and by comparison with literature spectral data. 相似文献
63.
Patrícia Valentão Rui F. Gonçalves Cristóvão Belo Paula Guedes de Pinho Paula B. Andrade Federico Ferreres 《Journal of separation science》2010,33(20):3168-3176
Piper betle is a species growing in South East Asia, where its leaves are economically and medicinally important. To screen the highest possible number of volatile and semivolatile components, the leaves were subjected to headspace solid‐phase microextraction, hydrodistillation and Soxhlet extraction, prior to analysis by GC/MS. Fifty compounds (identified by comparison with standard compounds or tentatively by National Institute of Standards and Technology database) were determined, 23 being described for the first time in this matrix. An aqueous extract was also analysed, in which only seven compounds were characterized. The organic acids' composition of this extract was determined by HPLC/UV and eight compounds are reported for the first time in P. betle. This extract also displayed acetylcholinesterase inhibitory capacity. 相似文献
64.
António P Alves de Matos Patrícia A Carvalho Arlindo Almeida Luís Duarte Rui Vilar Jorge Leit?o 《Microscopy and microanalysis》2007,13(5):390-396
Sialoliths from parotid and submaxillar glands have been characterized. Fractured and polished surfaces revealed an intrinsic structural diversity across the calculi sections. In general, the calculi presented highly mineralized amorphous-looking cores surrounded by concentric alternating mineralized and organic layers. The thickness of these layers decreased from the outer regions toward the center of the sialolith, illustrating a sequence of growth stages. Nevertheless, a significant variability could be detected among the specimens. In some cases, the calculi displayed multiple cores and lacked concentric laminated structures. In other instances, the specimens exhibited extensive regions of globular structures. In these cases, the globule diameter decreased across the radius toward the center of the sialoliths, and the globular structures tended to reorganize, forming bright and dark laminated layers surrounding the core. The participation of globular structures in the layer formation process points to morphogenetic mechanisms not previously described. 相似文献
65.
Lopes PS Kaneko TM Takano CY Lacerda AC Latorre LR Kato MJ 《Journal of AOAC International》2003,86(4):681-684
A validated method was developed for determination of diclofenac sodium, considered a model hydrophilic drug for in vitro permeation studies, in Eagle's Minimum Essential Medium (MEM) with Earle's balanced salt solution. Liquid chromatography was used to determine diclofenac sodium. This method was developed with a reversed-phase column Supercosil LC 18, DB 25 cm x 4.5 mm; the mobile phase was methanol with 3% (v/v) acetic acid-Milli-Q water (74 + 26), and detection was at 283 nm. The detection and quantitation limits were 2.41 x 10(-8) and 3.31 x 10(-5) microg/microL, respectively. The accuracy within-day (n = 3) and day-to-day (n = 7) was 98.83%; the mean variation coefficient for inter- (n = 7) and intraday precision (n = 3) was 12.20%, thus, not exceeding 15%. This method can be used as an analytical procedure for the determination of diclofenac sodium in MEM for in vitro permeation studies. 相似文献
66.
In this work, Amberlite XAD-2 resin functionalized with 4,5-dihydroxy-1,3-benzenedisulfonic acid was synthesized, characterized and applied as a new packing material for an on-line system to nickel preconcentration. The method is based on the sorption of Ni(II) ions in a minicolumn containing the synthesized resin, posterior desorption using an acid solution and measurement of the nickel by spectrophotometry (PAR method). The optimization of the system was performed using factorial design and Doehlert matrix considering five variables: eluent concentration, PAR solution pH, sample flow rate, PAR solution concentration and sample pH. Signals were measured as peak height by using an instrument software. Using the experimental conditions defined in the optimization, the method allowed nickel determination with achieved sampling rate of 25 samples per hour, detection limit (3 s) of 2 μg l−1 and precision (assessed as the relative standard deviation) of 8.2-2.6%, for nickel solutions of 10.0-200.0 μg l−1 concentration, respectively. The experimental enrichment factor of the proposed system was 46, for 120 s preconcentration time. The proposed procedure was applied for nickel determination in food samples. Recoveries of spike additions (5 or 10 μg g−1) to food samples were quantitative (94-110%). 相似文献
67.
Tasinkevych M Silvestre NM Patrício P Telo da Gama MM 《The European physical journal. E, Soft matter》2002,9(4):341-347
The interaction between two disks immersed in a 2D nematic is investigated i) analytically using the tensor order parameter
formalism for the nematic configuration around isolated disks and ii) numerically using finite-element methods with adaptive
meshing to minimize the corresponding Landau-de Gennes free energy. For strong homeotropic anchoring, each disk generates
a pair of defects with one-half topological charge responsible for the 2D quadrupolar interaction between the disks at large
distances. At short distance, the position of the defects may change, leading to unexpected complex interactions with the
quadrupolar repulsive interactions becoming attractive. This short-range attraction in all directions is still anisotropic.
As the distance between the disks decreases, their preferred relative orientation with respect to the far-field nematic director
changes from oblique to perpendicular.
Received 1 October 2002 and Received in final form 12 November 2002
RID="a"
ID="a"e-mail: miko@cii.fc.ul.pt 相似文献
68.
Patrícia Pinto Maria J. Calhorda Vitor Félix Teresa Avilés Michael G. B. Drew 《Monatshefte für Chemie / Chemical Monthly》2000,3(4):1253-1265
The reaction between [Cu(NCMe)4][PF6] and 1,1′-bis-(diphenylphosphino)-ferrocene (dppf) in several ratios, solvents, and conditions led to the synthesis and structural characterization of the Cu(I) complexes [Cu(dppf)(Odppf)][PF6] (1), [(dppf)Cu(μ-dppf)Cu(dppf)][PF6]2 (2), and [(dppf)Cu(μ-Cl)2Cu(dppf)] (3). Although 1 and the cation in 2 were known, the first was structurally characterized for the first time, exhibiting a significant asymmetry in the coordination sphere of Cu(I) owing to the presence of oxygen. In 2, the PF6 − anion led to an interesting crystal packing with large open channels containing water. Finally, DFT calculations on a model of 3 showed that its HOMO exhibits, besides Fe, a significant Cu and Cl character, which is reflected in its electrochemical properties. 相似文献
69.
Eutectic mixtures as a green alternative for efficient catalyst recycling in atom transfer radical polymerizations 下载免费PDF全文
Pedro Maximiano Patrícia V. Mendonça Madson R. E. Santos João R. C. Costa Tamaz Guliashvili Arménio C. Serra Jorge F. J. Coelho 《Journal of polymer science. Part A, Polymer chemistry》2017,55(3):371-381
A new solvent mixture, based on ethanol/reline (EM: eutectic mixture), was investigated for the supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) of methyl acrylate (MA) near room temperature, for the first time, affording complete catalyst recovery and reuse. The kinetic results revealed that the polymerizations were controlled, with polymers having narrow molecular weight distributions (? < 1.2). The “living” character of the resultant PMA was confirmed by the synthesis of a well‐defined PMA‐b‐PBA block copolymer. Remarkably, it was demonstrated that the Cu(0)/CuBr2/Me6TREN (Me6TREN: tris[2‐(dimethylamino)ethyl]amine) could be recovered from the final reaction mixture and reused for new successful SARA ATRP of MA, suggesting that the reported system could be very attractive from both the economic and environmental perspectives. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 371–381 相似文献
70.