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121.
Breakthrough curve measurements of SO2 and water vapor were carried out on a number of selected mordenite and pentasil zeolites from their binary and ternary mixtures with CO2 at 50 and 100°C. SO2 capacities of these samples were found to be significantly reduced by the presence of water. Competitive adsorption led to unusually high overshoot peaks of SO2 breakthrough curves. On the other hand, SO2 was found to displace water on the samples with very high silica to alumina ratio. A linear driving force, isothermal model was used to predict the breakthrough curves. Langmuir and extended Langmuir equilibrium models were used to describe the equilibrium properties of water and SO2, respectively. The overall mass transfer resistance obtained from the model was compared to the values calculated from a simplified biporous adsorbent model to shed some light on the adsorption kinetics. 相似文献
122.
Raffaella Rolli Sabina Ronchin Maurizio Montagna Enrico Moser Claire Duverger Victor K. Tikhomirov Animesh Jha Maurizio Ferrari 《Journal of Non》2001,280(1-3):269-276
Rare-earth-doped fluoride glasses are attractive materials for photonics, since they combine a transmission region from ultraviolet to infrared and low vibrational cut-off energy. We report on the spectroscopic properties of aluminium fluorophosphate glasses doped with 0.1, 0.6, 1, 3 and 10 mol% Pr3+. Yellow-to-blue upconversion was observed upon pulsed and continuous-wave (CW) excitation at 575 nm. The temporal evolution of the upconverted fluorescence is characterised by rise and decay times depending on Pr3+ concentration. The upconversion intensity has a quadratic dependence on incident pump power, indicating a two-step process. The upconversion emission is described in the framework of a two-ion energy transfer mechanism. Emission in the second telecom window (1.3 μm) was measured upon excitation at 976 nm. 相似文献
123.
124.
Sabina Brazevic Dr. Mikołaj Baranowski Prof. Marek Sikorski Dr. Michał F. Rode Dr. Gotard Burdziński 《Chemphyschem》2020,21(13):1402-1407
Recent efforts in designing new 3H-naphthopyran derivatives have been focused on efficient coloration process with a short fading time of the colored transoid-cis TC isomer. It is desirable to avoid photoisomerization of TC leading to transoid-trans TT isomers in the photoreaction. Long lifetime of TT can hamper fast applications such as dynamic holographic materials and molecular actuators, the residual color is one of the serious issues for photochromic lenses. Herein we characterize the photophysical and photochemical channels of TC excited state deactivation competing with the unwanted TC → TT isomerization process. Transient absorption spectroscopy reveals a very short lifetime of the singlet excited TC (≈0.8 ps) and its deactivation channels as S1→S0 internal conversion (major), intersystem crossing S1→T1, pyran ring formation, photoenolization and TC → TT isomerization. Computations support the S1→S0 and T1→S0 channels as responsible for photostabilization of the TC form. 相似文献
125.
Hanna Kowalska Jolanta Kowalska Anna Ignaczak Ewelina Masiarz Ewa Domian Sabina Galus Agnieszka Ciurzyska Agnieszka Salamon Agnieszka Zajc Agata Marzec 《Molecules (Basel, Switzerland)》2021,26(13)
The aim of this study was to find the effect of kale and dietary fibre (DF) on the physicochemical properties, nutritional value and sensory quality of multigrain bars. A recipe of multigrain bars was prepared with the addition of fresh kale (20% and 30%) and DF preparations (apple, blackcurrant, chokeberry and hibiscus). The bars were baked at 180 °C for 20 min. These snack bars, based on pumpkin seeds, sunflower seeds, flaxseed and wholegrain oatmeal, are a high-calorie product (302–367 kcal/100 g). However, the composition of the bars encourages consumption. In addition to the ability to quickly satisfy hunger, such bars are rich in many natural ingredients that are considered pro-health (high fibre content (9.1–11.6 g/100 g), protein (11.2–14.3 g/100 g), fat (17.0–21.1 g/100 g, including unsaturated fatty acids), carbohydrates (20.5–24.0 g/100 g), as well as vitamins, minerals and a large number of substances from the antioxidant group. The addition of kale caused a significant increase of water content, but reduction in the value of all texture parameters (TPA profiles) as well as calorific values. The content of polyphenols was strongly and positively correlated with the antioxidant activity (r = 0.92). In the bars with 30% addition of kale (422 mg GA/100 g d.m.), the content of polyphenols was significantly higher than based ones (334 mg GA/100 g d.m.). Bars with the addition of the DF were characterized by a higher antioxidant activity, and the content of carotenoids, chlorophyll A and B and polyphenols. High sensory quality was demonstrated for all (from 4.8 to 7.1 on a 10-point scale). The addition of fibre preparations was also related to technological aspects and allows to create attractive bars without additional chemicals. 相似文献
126.
The conformation of single molecules of dialkyl poly para phenylene ethynylenes (PPEs), electro-active polymers, is studied in solutions using molecular dynamics simulations. The conformation of conjugated polymers affects their electro-optical properties and therefore is critical to their current and potential uses, though only limited theoretical knowledge is available regarding the factors that control their configuration. The present study investigates the affects of molecular parameters including molecular weight of the polymer and chemical structure of the side chains of PPEs in different solvents on the conformation of the polymers. The PPEs are modeled atomistically where the solvents are modeled both implicitly and explicitly. The study finds that PPEs assume extended configuration which is affected by the length of the polymer backbone and the nature and length of substituting side chains. While the polymer remains extended, local dynamics is retained and no long range correlations are observed within the backbone. The results are compared with scattering experiments. 相似文献
127.
Rosanna Toniolo Nicolò Dossi Andrea Pizzariello Sabina Susmel Gino Bontempelli 《Electroanalysis》2011,23(3):628-636
Based on preliminary voltammetric investigations at unmodified and modified electrodes in aqueous solutions buffered at different pHs, a profitable thin layer dual‐electrode detector was developed for the selective and simultaneous determination of ascorbic acid (AA) and hydrogen peroxide present in the same samples. It consists of a small thickness (0.1 mm) cell, used as a detector for a flow injection system, in which a glassy carbon (GC) and a polyeugenol coated Pt electrode are encased. The GC electrode is selective for AA, thanks to the potential applied (0.3 V vs. Ag/AgCl,Cl?sat), while H2O2 alone can be oxidized at the Pt electrode (0.75 V), thanks to the size selectivity and electrostatic screen properties displayed by the polyeugenol coating layer which prevents oxidation of ascorbate anions. Repeatable sharp peaks (±4.5 %) were detected for both analytes over wide linear ranges (0.005–1.000 mM) and detection limits of about 10?6 M (176 ppb) and 5×10?7 M (16 ppb) were inferred for AA and H2O2 respectively. This flow injection approach was applied to the analysis of some orange‐taste soft drinks, used as prototype real samples, spiked with controlled amounts of both analytes, thus inferring good recoveries which pointed out that deviations never exceeding 5 % affected the relevant accuracy. 相似文献
128.
Sabina Salkic Logan H. Eckler Matthew J. Nee 《Journal of Raman spectroscopy : JRS》2013,44(12):1746-1752
The photocatalytic degradation of the X‐ray contrast agents iohexol and diatrizoate are monitored by in situ Raman spectrometry measurements in aqueous solution with a TiO2 photocatalyst. Spectral features and changes are interpreted with the use of density functional theory calculations. While we observe similar results to those published previously, significant changes seen in the Raman spectrum allow us to better identify the mechanisms without the need for deductive approaches or complicated sample preparation. Diatrizoate spectra are consistent with hydroxyl radical attack leading to the loss of CO2. Iohexol is more difficult to interpret, representing a current challenge to the use of Raman spectrometry for real‐time monitoring of photocatalytic degradation experiments. We explore internal standards that can be added to gauge overall degradation rates to some extent. Potential extensions of the work are described, particularly in terms of increased rate of data acquisition and more general application. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
129.
Homo‐ and Heteronuclear Compounds with a Symmetrical Bis‐hydrazone Ligand: Synthesis,Structural Studies,and Luminescent Properties 下载免费PDF全文
Dr. Sabina Rodríguez‐Hermida Dr. Ana B. Lago Prof. Rosa Carballo Dr. Oscar Fabelo Prof. Ezequiel M. Vázquez‐López 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6605-6616
Nine new coordination compounds have been synthesized by the reaction of salts of bivalent metal ions (a=ZnII, b=CuII, c=NiII, d=CoII) with the bis(benzoylhydrazone) derivative of 4,6‐diacetylresorcinol (H4L). Three kinds of complexes have been obtained: homodinuclear compounds [M2(H2L)2]?nH2O ( 1 a , 1 b , 1 c , and 1 d ), homotetranuclear compounds [M4(L)2]?n(solv) ( 2 a and 2 c ), and heterotetranuclear compounds [Zn2M2(L)2]?n(solv) ( 2 ab , 2 ac , and 2 ad ). The structures of the free ligand H4L?2 DMSO and its complexes [Zn2(H2L)2(DMSO)2] ( 1 a* ), [Zn4(L)2(DMSO)6] ( 2 a* ), and [Zn0.45Cu3.55(L)2(DMSO)6]?2 DMSO ( 2 ab* ) were elucidated by single‐crystal X‐ray diffraction. The ligand shows luminescence properties and its fluorimetric behavior towards MII metals (M=Zn, Cu, Ni and Co) has been studied. Furthermore, the solid‐state luminescence properties of the ligand and compounds have been determined at room temperature. 1H NMR spectroscopic monitoring of the reaction of H4L with ZnII showed the deprotonation sequence of the OH/NH groups upon metal coordination. Heteronuclear reactions have also been monitored by using ESI‐MS and spectrofluorimetric techniques. 相似文献