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排序方式: 共有127条查询结果,搜索用时 15 毫秒
1.
Tereza C. R. dos Santos Ricardo Q. Aucélio Reinaldo C. Campos 《Mikrochimica acta》2003,142(1-2):63-66
A simple and direct spectrofluorimetric method has been developed for the determination of aluminum using alizarin red PS
(1,2,4-trihydroxy 9,10-anthraquinone-3-sulfonic acid). The method is based on the strong fluorescence (480/564 nm) of Al3+ and alizarin red. Experimental parameters such as pH, concentration of the ligand, ionic strength of the solution, reaction
time and temperature were optimized in order to maximize the analytical signal. Interferences of several ions (anions and
cations) were studied and evaluated. The linear range of the method extends from 3 to 100 μg L−1. Limit of detection (3sb) was 0.9 μg L−1. The method was tested with a silicate certified reference material. Interferences were eliminated by a liquid extraction
with cupferron.
Author for correspondence. E-mail: aucelior@rdc.puc-rio.br
Received September 10, 2002; accepted January 15, 2003
Published online May 5, 2003 相似文献
2.
Jarmila Duskova Jiri Labsky Ivana Cisarova Tereza Skalova Jan Dohnalek Jindrich Hasek 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(9):o563-o566
The asymmetric unit of the title compound, C11H5D16N2O2·0.33H2O, is formed by three crystallographically independent piperidin‐1‐yloxyl molecules and a molecule of water. The molecules are crosslinked by nine hydrogen bonds into layers parallel with the ac plane. The water molecule contributes to the stability of the low‐symmetry arrangement by four hydrogen bonds. 相似文献
3.
4.
Jan Gajdziok Tereza Bautzová Miloslava Rabišková Yann Pellequer Alf Lamprecht 《Cellulose (London, England)》2013,20(3):1237-1248
Oxycellulose belongs to the wide range of pharmaceutically and medically used cellulose derivatives unique in its properties of biodegradability, non-toxicity, antioxidative activity, haemostasis supporting, tissue healing improvement, etc. Glycyrrhizin (Gly) represents the most prominent licorice triterpenoid glycoside, which is responsible for its pharmacological activity, and is closely linked to increasing levels of gastroprotective prostaglandins. In order to study the anti-ulcer activity of oxycellulose sodium and Gly, pellets containing only oxycellulose, or in combination with glycyrrhizin, were prepared using an extrusion/spheronization method. The physical properties and in vitro release rate of the prepared pellets were tested. Based on the obtained results, one sample prepared from oxycellulose only, and one containing glycyrrhizin were chosen for in vivo testing. The healing effect of the prepared pellet formulations was evaluated in the acetic acid induced gastric ulcers in rats. The improvement in gastric ulcer healing was documented for myeloperoxidase activity, alkaline phosphatase activity and gastric wall mucin levels using the Alcian blue binding capacity. The tested pellets significantly reduced myeloperoxidase and alkaline phosphatase activity, and increased gastric wall mucus levels compared to the non-treated group. The in vivo tests showed that oral administration of the prepared pellets accelerated the healing of gastric ulcers in rats. 相似文献
5.
Lidiane C. Castro Yasmim R. Jaconiano Tereza C. S. Evangelista Sabrina B. Ferreira 《合成通讯》2019,49(10):1316-1324
The synthesis and characterization of three novel N2O-donor ligands containing the group 4-[1-β-d-2,3,4,6-tetra-O-acetyl-galactosyl)]benzaldehyde are presented. The insertion of this group was designed to increase the absorption of the prodrug in tumor cells, and is part of an ongoing work in our group with tridentate ligands to develop potential cobalt(III) prodrugs. The synthetic route described here allowed the isolation of pure ligands with yields ranged 81–89%. Finally, compounds were characterized by IR, NMR and HRMS (ESI+). 相似文献
6.
7.
Dr. Quentin Bonnin Tereza Edlová Dr. E. Daiann Sosa Carrizo Prof. Dr. Paul Fleurat-Lessard Dr. Stéphane Brandès Dr. Hélène Cattey Dr. Philippe Richard Prof. Dr. Pierre Le Gendre Dr. Adrien T. Normand 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(72):18175-18187
Cationic amidotitanocene complexes [Cp2Ti(NPhAr)][B(C6F5)4] (Cp=η5-C5H5; Ar=phenyl ( 1 a ), p-tolyl ( 1 b ), p-anisyl ( 1 c )) were isolated. The bonding situation was studied by DFT (Density Functional Theory) using EDA-NOCV (Energy Decomposition Analysis with Natural Orbitals for Chemical Valence). The polar Ti−N bond in 1 a–c features an unusual inversion of σ and π bond strengths responsible for the balance between stability and reactivity in these coordinatively unsaturated species. In solution, 1 a–c undergo photolytic Ti−N cleavage to release Ti(III) species and aminyl radicals ⋅ NPhAr. Reaction of 1 b with H3BNHMe2 results in fast homolytic Ti−N cleavage to give [Cp2Ti(H3BNHMe2)][B(C6F5)4] ( 3 ). 1 a–c are highly active precatalysts in olefin hydrogenation and silanes/amines cross-dehydrogenative coupling, whilst 3 efficiently catalyzes amine-borane dehydrogenation. The mechanism of olefin hydrogenation was studied by DFT and the cooperative H2 activation key step was disclosed using the Activation Strain Model (ASM). 相似文献
8.
Stepan Geri Tereza Krunclova Dr. Olga Janouskova Dr. Jiri Panek Dr. Martin Hruby Daniel Hernández-Valdés Dr. Benjamin Probst Prof. Roger A. Alberto Dr. Constantin Mamat Dr. Manja Kubeil Dr. Holger Stephan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(48):10992-11006
Two photoactivatable dicarbonyl ruthenium(II) complexes based on an amide-functionalised bipyridine scaffold (4-position) equipped with an alkyne functionality or a green-fluorescent BODIPY (boron-dipyrromethene) dye have been prepared and used to investigate their light-induced decarbonylation. UV/Vis, FTIR and 13C NMR spectroscopies as well as gas chromatography and multivariate curve resolution alternating least-squares analysis (MCR-ALS) were used to elucidate the mechanism of the decarbonylation process. Release of the first CO molecule occurs very quickly, while release of the second CO molecule proceeds more slowly. In vitro studies using two cell lines A431 (human squamous carcinoma) and HEK293 (human embryonic kidney cells) have been carried out in order to characterise the anti-proliferative and anti-apoptotic activities. The BODIPY-labelled compound allows for monitoring the cellular uptake, showing fast internalisation kinetics and accumulation at the endoplasmic reticulum and mitochondria. 相似文献
9.
Artem Yakovliev Tymish Y. Ohulchanskyy Roman Ziniuk Tereza Dias Xin Wang Hao Xu Guanying Chen Junle Qu Anderson S. L. Gomes 《Particle & Particle Systems Characterization》2020,37(2):1900445
In this work, the application of near infrared (NIR)-emitting NaYbF4:1%Tm3+@NaLuF4:30%Nd3+ core–shell nanoparticles is reported for noninvasive probing and monitoring the temperature during photopolymerization of dental materials. When excited at 808 nm, the synthesized nanoparticles emit NIR photoluminescence (PL) with two distinctive peaks at 865 and 980 nm which correspond to radiative transitions from the doped Nd3+ and Yb3+ ions, respectively. Luminescence intensity ratio between these two bands is found to vary with temperature due to temperature-dependent electronic excitation energy transfer between Nd3+ and Yb3+ ions at the core/shell interface. This finding allows luminescence ratiometric evaluation of the in situ temperature during photopolymerization of resin cement (doped with nanoparticles) in a veneer placement procedure. In addition, the NIR emission also enables PL imaging of the distribution of the adhesive under the veneer. The results highlight that rare-earth ions–doped nanoparticles with both excitation and emission in the NIR spectral range are advantageous for both PL-based nanothermometry and imaging due to the reduced attenuation of NIR light by dental ceramics. 相似文献
10.
Tereza Tůmová Lenka Monincová Václav Čeřovský Václav Kašička 《Electrophoresis》2016,37(23-24):3186-3195
Capillary electrophoresis (CE) was employed for the determination of thermodynamic acidity constants (pKa) and actual ionic mobilities of polycationic antimicrobial peptides (AMPs). The effective electrophoretic mobilities of AMPs were measured by CE in a series of the background electrolytes within a wide pH range (2.00–12.25), at constant ionic strength (25 mM) and ambient temperature, using polybrene coated fused silica capillaries to suppress sorption of cationic AMPs to the capillary wall. Eventually, Haarhoff–Van der Linde peak fitting function was used for the determination of correct migration times of some AMPs peaks that were distorted by electromigration dispersion. The measured effective mobilities were corrected to 25°C. Mixed acidity constants, , and actual ionic mobilities, mi, of AMPs were determined by the nonlinear regression analysis of pH dependence of their effective mobilities. The values were recalculated to thermodynamic pKas using the Debye–Hückel theory. Thermodynamic pKa of imidazolium group of histidine residues was found to be in the range 3.72–4.98, pKa of α‐NH3+ group was in the range 6.14–6.93, and pKa of ε‐NH3+ group of lysine spanned the interval 7.26–9.84, depending on the particular amino acid sequence of the AMPs. Actual ionic mobilities of AMPs with positive charges from one to six elementary units achieved values (9.8 – 36.5) × 10?9 m2V?1s?1. 相似文献