Search results for "compounds"
showing 10 items of 3372 documents
Ilgstošas fosforescences dizains karbazola atvasinājumos
2020
Ilgstošas fosforescences dizains karbazola atvasinājumos. Mazarevičs A., zinātniskie vadītāji Mg. chem. Leduskrasts K., Prof., Dr. chem. Sūna E. Bakalaura darbs, 62 lapaspuse, 55 attēli, 10 tabula, 42 literatūrās avoti, 4 pielikumi. Latviešu valodā. Literatūras apskatā analizēta luminiscence un fosforescence. Iekļauti organiskās fosforescences iegūšanas piemēri izmantojot kristalizāciju, smagā atoma efektu, starpmolekulāru un iekšmolekulāru mijiedarbību veidošanu kā arī nedalīta elektronu pāra vai karbonilgrupas ievadīšanu molekulā. Rezultātu izvērtējumā aprakstīta sintezēto savienojumu iegūšana, analizētas to luminiscentās īpašības, kā arī apskatīti rentgenstruktūras attēli no sintezētajie…
Spectrophotometric investigation of the binding of vitamin E to water-containing reversed micelles.
2002
The distribution constants of vitamin E partitioned between apolar organic phase and water-containing reversed micelles of sodium bis (2-ethylhexyl) sulfosuccinate (AOT), didodecyldimethylammonium bromide (DDAB), soybean phosphatidylcholine (lecithin) and tetraethylene glycol monododecyl ether (C12E4) have been evaluated by a spectrophotometric method. The results suggest that in the presence of domains from apolar organic solvent to surfactant and to water, vitamin E is partitioned between the micellar palisade layer and the organic solvent and also that its binding strength to reversed micelles depends mainly by specific interactions between the head group of vitamin E and that of the sur…
Analytical methodologies for atomic spectrometric determination of metallic oxides in UV sunscreen creams.
2000
In this study, methodologies for determining titanium oxide, zinc oxide and iron oxide are proposed and assayed in commercial sunscreen products. The proposed methodology for TiO2, determination in sunscreens is based on a microwave-assisted treatment for digesting the organic components in a closed teflon reactor in presence of HNO3 and HCl. Titanium is determined by inductive coupled plasma emission spectrometry (ICP-AES). The proposed methodologies for measuring ZnO and Fe2O3 are based on a sample emulsification in water with a non ionic tensioactive and IBMK, followed by Zn and Fe determination by flame atomic absorption spectrometry (FAAS). The methodologies allow a precise and accurat…
Influence of photo-initiators in the preparation of methacrylate monoliths into poly(ethylene-co-tetrafluoroethylene) tubing for microbore HPLC.
2020
[EN] In this study, poly(butyl methacrylate-co-ethyleneglycol dimethacrylate) polymeric monoliths were in situ developed within 0.75 mm i.d. poly(ethylene-co-tetrafluoroethylene) (ETFE) tubing by UV polymerization via three different free-radical initiators fscce-azobisisobutyronitrile (AIBN), 2,2-dimethoxy-2-phenylacetophenone (DMPA) and 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (MTMPP). The influence of the nature of each photo-initiator and irradiation time on the morphological features of the polymer was investigated by scanning electron microscopy, and the chromatographic properties of the resulting microbore columns were evaluated using alkyl benzenes as test substances. The …
Antioxidant betalains from cactus pear (Opuntia ficus-indica) inhibit endothelial ICAM-1 expression.
2004
It has been suggested that some pigments would have antioxidant properties and that their presence in dietary constituents would contribute to reduce the risk of oxidative stress–correlated diseases. Among others, inflammatory response depends on redox status and may implicate oxidative stress. Vascular endothelial cells are a direct target of oxidative stress in inflammation. We have tested the impact of the free radical scavenger and antioxidant properties of betalains from the prickle pear in an in vitro model of endothelial cells. Here we show the capacity of betalains to protect endothelium from cytokine- induced redox state alteration, through ICAM-1 inhibition. KEYWORDS: endothelial …
Occurrence of priority pollutants in WWTP effluents and Mediterranean coastal waters of Spain
2011
A comprehensive study aimed at evaluating the occurrence, significance of concentrations and spatial distribution of priority pollutants (PPs) along the Comunidad Valenciana coastal waters (Spain) was carried out in order to fulfil the European Water Framework Directive (WFD). Additionally, PP concentrations were also analysed in the effluent of 28 WWTPs distributed along the studied area. In coastal waters 36 organic pollutants of the 71 analysed, including 26 PPs were detected although many of them with low frequency of occurrence. Only 13 compounds, which belong to four different classes (VOCs, organochlorinated pesticides, phthalates and tributyltin compounds (TBT)) showed a frequency o…
Nitric oxide increases the decay of matrix metalloproteinase 9 mRNA by inhibiting the expression of mRNA-stabilizing factor HuR.
2003
Dysregulation of extracellular matrix turnover is an important feature of many inflammatory processes. Rat renal mesangial cells express high levels of matrix metalloproteinase 9 (MMP-9) in response to inflammatory cytokines such as interleukin-1 beta. We demonstrate that NO does strongly destabilize MMP-9 mRNA, since different luciferase reporter gene constructs containing the MMP-9 3' untranslated region (UTR) displayed significant reduced luciferase activity in response to the presence of NO. Moreover, by use of an in vitro degradation assay we found that the cytoplasmic fractions of NO-treated cells contained a higher capacity to degrade MMP-9 transcripts than those obtained from contro…
Exploring the anticancer potential of pyrazolo[1,2-a]benzo[1,2,3,4] tetrazin-3-one derivatives: The effect on apoptosis induction, cell cycle and pro…
2013
In order to investigate their anticancer potential, four new pyrazolo[1,2-a]benzo[1,2,3,4]-tetrazinone derivatives, designed through the chemometric protocol VLAK, and three of the most active compounds of the previous series have been evaluated on some cellular events including proliferation, apoptosis induction, and cell cycle. The NCI one dose (10 mu M) screening revealed that the 8,9-di-methyl derivative showed activity against Leukemia (CCRF-CEM) and Colon cancer cell line (COLO 205), reaching 81% and 45% of growth inhibition (GI), respectively. Replacement of the two methyl groups with two chlorine atoms maintained the activity toward Leukemia cell (CCRF-CEM, GI 77%) and selectively e…
Theoretical study of the electronic spectrum of p-benzoquinone
1999
The electronic excited states of p-benzoquinone have been studied using multiconfigurational second-order perturbation theory (CASPT2) and extended atomic natural orbital (ANO) basis sets. The calculation of the singlet–singlet and singlet–triplet transition energies comprises 19 valence singlet excited states, 4 valence triplet states, and the singlet 3s,3p, and 3d members of the Rydberg series converging to the first four ionization limits. The computed vertical excitation energies are found to be in agreement with the available experimental data. Conclusive assignments to both valence and Rydberg states have been performed. The main features of the electronic spectrum correspond to the π…
Mixed‐valence trinuclear manganese clusters : Influence of the electronic transfer on the magnetic properties
1990
The magnetic behavior of mixed‐valence trinuclear clusters d4‐d4‐d5 is discussed on the basis of a model which takes into account valence delocalization and Heisenberg exchange. This model considers the competing effect between the electronic transfer and the localization of the extra electron due to an asymmetry of the triangular entity. The magnetic properties of the mixed‐valence oxo‐centered Mn(II)‐Mn(III)‐Mn(III) complexes formulated as Mn3O(O2CR)6L3 (R=Me, L=pyridine) are discussed on the basis of the developed model, supporting a significant intramolecular electron transfer. A comparison of these results to those previously reported by assuming a valence‐trapped model is given. Carlo…