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961.
In this short paper, a critical analysis of the Neutrosophic, Pythagorean and some other novel fuzzy sets theories foundations is provided, taking into account that they actively used for the solution of the decision-making problems. The shortcomings of these theories are exposed. It is stated that the independence hypothesis, which is a cornerstone of the Neutrosophic sets theory, is not in line with common sense and therefore leads to the paradoxical results in the asymptotic limits of this theory. It is shown that the Pythagorean sets theory possesses questionable foundations, the sense of which cannot be explained reasonably. Moreover, this theory does not completely solve the declared problem. Similarly, important methodological problems of other analyzed theories are revealed. To solve the interior problems of the Atanassov’s intuitionistic fuzzy sets and to improve upon them, this being the reason most of the criticized novel sets theories were developed, an alternative approach based on extension of the intuitionistic fuzzy sets in the framework of the Dempster–Shafer theory is proposed. No propositions concerned with the improvement of the Cubic sets theory and Single-Valued Neutrosophic Offset theory were made, as their applicability was shown to be very dubious. In order to stimulate discussion, many statements are deliberately formulated in a hardline form. 相似文献
962.
Short reversed-phase columns (50 mm x 4.6 mm Gemini C(18)) were dynamically coated with carboxybetaines of the general structure, C(12)H(25)N(+)(CH(3))(2)(CH(2))(n)COOH, namely (N-dodecyl-N,N-dimethylammonio)undecanoate, DDMAU (n=10) and (N-dodecyl-N,N-dimethylammonio)butyrate, DDMAB (n=3), and investigated for the separation of inorganic anions in ion chromatography. The role of the ionic strength of coating surfactant solutions on their adsorption and resultant column capacity was studied. The retention of inorganic anions was investigated with different eluents at various concentrations and pH. Interestingly, no retention for anions was found with pure water as the eluent, but the addition of small amounts of electrolytes, up to 0.1 mM, caused a sharp increase in the retention of analytes. The effect of increasing anion retention with an increase in eluent cation charge was also observed. Based on this effect a new cation charge gradient concept was proposed and applied to the separation of a standard mixture of anions. 相似文献
963.
Sequential extraction and thermal desorption of mercury from contaminated soil and tailings from Mongolia 总被引:1,自引:0,他引:1
Pavel Coufalík Pavel Krásenský Marek Dosbaba Josef Komárek 《Central European Journal of Chemistry》2012,10(5):1565-1573
Mercury forms in contaminated environmental samples were studied by means of sequential extraction and thermal desorption from the solid phase. The sequential extraction procedure involved the following fractions: water soluble mercury, mercury extracted in acidic conditions, mercury bound to humic substances, elemental Hg and mercury bound to complexes, HgS, and residual mercury. In addition to sequential extraction, the distribution of mercury species as a function of soil particles size was studied. The thermal desorption method is based on the thermal decomposition or desorption of Hg compounds at different temperatures. The following four species were observed: Hg0, HgCl2, HgS and Hg(II) bound to humic acids. The Hg release curves from artificial soils and real samples were obtained and their applicability to the speciation analysis was considered. 相似文献
964.
Száková J Tlustos P Goessler W Pavlíková D Balík J Schlagenhaufen C 《Analytical and bioanalytical chemistry》2005,382(1):142-148
In this work three mild extraction agents for determination of plant-available fractions of elements in soil were evaluated for arsenic speciation in soil samples. Pepper (Capsicum annum, L.) var. California Wonder was cultivated in pots, and aqueous solutions of arsenite, arsenate, methylarsonic acid, and dimethylarsinic acid, at a concentration of 15 mg As kg–1 soil, were added at the beginning of the experiment. Control pots (untreated) were also included. Deionized water, 0.01 mol L–1 CaCl2, and 0.05 mol L–1 (NH4)2SO4 were used to extract the plant-available fraction of the arsenic compounds in soil samples collected during the vegetation period of the plants. Whereas in control samples the extractable arsenic fraction did not exceed 1% of total arsenic content, soil amendment by arsenic compounds resulted in extraction of larger amounts, which varied between 1.4 and 8.1% of total arsenic content, depending on soil treatment and on the extracting agent applied. Among arsenic compounds determined by HPLC–ICPMS arsenate was predominant, followed by small amounts of arsenite, methylarsonic acid, and dimethylarsinic acid, depending on the individual soil treatment. In all the experiments in which methylarsonic acid was added to the soil methylarsonous acid was detected in the extracts, suggesting that the soil bacteria are capable of reducing methylarsonic acid before a further methylation occurs. No significant differences were observed between analytical data obtained by using different extraction procedures. 相似文献
965.
This review points out some important trends in the development of the detection techniques for small ions in CE. On the basis of selected literature references it briefly discusses some general requirements on detection techniques in CE. Various optical measurements, mass spectrometric approaches and electrochemical detection techniques are dealt with. Some specific features of microchip CE separation and detection are pointed out and possibilities of dual detection are mentioned. The principal parameters of the above detection techniques are then briefly compared. 相似文献
966.
Natalia P. Zaksas Anna M. Timofeeva Pavel S. Dmitrenok Svetlana E. Soboleva Georgy Nevinsky 《Molecules (Basel, Switzerland)》2022,27(6)
Metal ions and other elements play many different critical roles in all biological processes. They can be especially important in high concentrations for the functioning of organisms living in seawater. It is important to understand how much the concentrations of different trace elements in such organisms can be higher than in seawater. Some marine organisms capable of rapid recovery after different injuries are fascinating in this regard. Sea cucumbers Eupentacta fraudatrix can completely restore all organs and the whole body within several weeks after their division into two parts. Here, for the first time, a comparison of the content of different elements in seawater, sea cucumber, and its very stable multiprotein complex (2000 kDa) was performed using two-jet plasma atomic emission spectrometry. Among the 18 elements we found in sea cucumbers, seawater contained only six elements in detectable amounts, and their content decreased in the following order: Mg > Ca > B > Sr ≈ Si > Cr (0.13–930 µg/g of seawater). The content of these elements in sea cucumbers was higher compared with seawater (-fold): Ca (714) > Sr (459) > Cr (75) > Si (42)> B (12) > Mg (6.9). Only four of them had a higher concentration in the protein complex than in seawater (-fold): Si (120.0) > Cr (31.5) > Ca (9.1) > Sr (8.8). The contents of Mg and B were lower in the protein complex than in seawater. The content of elements additionally found in sea cucumbers decreased in the order (µg/g of powder) of P (1100) > Fe (47) > Mn (26) > Ba (15) > Zn (13) > Al (9.3) > Mo (2.8) > Cu (1.4) > Cd (0.3), and in the protein complex, in the order of P (290) > Zn (51) > Fe (23) > Al (14) ≈ Ni (13) > Cu (7.5) > Ba (2.5) ≈ Co (2.0) ≈ Mn (1.6) > Cd (0.7) >Ag (0.2). Thus, sea cucumbers accumulate various elements, including those contained in very low concentrations in seawater. The possible biological roles of these elements are discussed here. 相似文献
967.
Linnea Lindh Olga Gordivska Samuel Persson Hannes Michaels Hao Fan Pavel Chbera Nils W. Rosemann Arvind Kumar Gupta Iacopo Benesperi Jens Uhlig Om Prakash Esmaeil Sheibani Kasper S. Kjaer Gerrit Boschloo Arkady Yartsev Marina Freitag Reiner Lomoth Petter Persson Kenneth Wrnmark 《Chemical science》2021,12(48):16035
A new generation of octahedral iron(ii)–N-heterocyclic carbene (NHC) complexes, employing different tridentate C^N^C ligands, has been designed and synthesized as earth-abundant photosensitizers for dye sensitized solar cells (DSSCs) and related solar energy conversion applications. This work introduces a linearly aligned push–pull design principle that reaches from the ligand having nitrogen-based electron donors, over the Fe(ii) centre, to the ligand having an electron withdrawing carboxylic acid anchor group. A combination of spectroscopy, electrochemistry, and quantum chemical calculations demonstrate the improved molecular excited state properties in terms of a broader absorption spectrum compared to the reference complex, as well as directional charge-transfer displacement of the lowest excited state towards the semiconductor substrate in accordance with the push–pull design. Prototype DSSCs based on one of the new Fe NHC photosensitizers demonstrate a power conversion efficiency exceeding 1% already for a basic DSSC set-up using only the I−/I3− redox mediator and standard operating conditions, outcompeting the corresponding DSSC based on the homoleptic reference complex. Transient photovoltage measurements confirmed that adding the co-sensitizer chenodeoxycholic acid helped in improving the efficiency by increasing the electron lifetime in TiO2. Time-resolved spectroscopy revealed spectral signatures for successful ultrafast (<100 fs) interfacial electron injection from the heteroleptic dyes to TiO2. However, an ultrafast recombination process results in undesirable fast charge recombination from TiO2 back to the oxidized dye, leaving only 5–10% of the initially excited dyes available to contribute to a current in the DSSC. On slower timescales, time-resolved spectroscopy also found that the recombination dynamics (longer than 40 μs) were significantly slower than the regeneration of the oxidized dye by the redox mediator (6–8 μs). Therefore it is the ultrafast recombination down to fs-timescales, between the oxidized dye and the injected electron, that remains as one of the main bottlenecks to be targeted for achieving further improved solar energy conversion efficiencies in future work.Iron-based photosensitizers for dye-sensitized solar cells with a rod-like push–pull design. Solar cell performance was limited by ultrafast (sub-ps) recombination, but yielded better performance than the homoleptic parent photosensitizer. 相似文献
968.
Pavel G. Khalatur Alexei R. Khokhlov Dmitrii A. Mologin Ekaterina A. Zheligovskaya 《Macromolecular theory and simulations》1998,7(3):299-316
The structure of aggregates in solutions of chain molecules with associating groups at one of the ends is studied by Monte Carlo computer simulations using the bond fluctuation model. The main attention is paid to the influence of additives of low-molecular-weight solvent solubilizing the aggregates. It is shown that upon the addition of solvent the aggregates adopt a three-layer structure with the ‘lake’ of the solvent molecules in the central region surrounded by the layer of associating end-groups of polymer chains, which in turn is surrounded by the outer corona formed by the chain tails. The equilibrium form of the aggregates becomes close to that of a droplet of low-molecular-weight liquids. The regimes are found when the addition of the low-molecular-weight solvent stabilizes the multiplets and even induces the aggregate formation. 相似文献
969.
Riccardo Tarroni Paolo Palmieri Pavel Rosmus 《International journal of quantum chemistry》1996,60(1):467-473
The adiabatic energy surfaces of the lowest three electronic states [2(2A′ and 2A′)] and 2Σ+[2A′] of the C2F radical were investigated by the Hartree-Fock multiconfiguration self-consistent field (HF—MCSCF) ab initio method using a large set of atomic natural orbitals (ANO) and an extended configuration space, and the results were shown to be in agreement with the predictions of valence theory for this radical. The electronic ground state was found to have a bent equilibrium structure, hence contradicting the Walsh rule which predicts for the isoelectronic molecules a 2 linear state. The three states were found to be nearly degenerate and the potential energy surfaces of the two lowest electronic states exhibit an avoided crossing at an energy ∼2000 cm−1 above the ground-state minimum, lower than the highest vibrational fundamental. The strong adiabatic interaction which is responsible for the ordering of the electronic states and their equilibrium geometry involves not only the bending coordinate as normally found for Renner-Teller pairs of states, but also the C—C stretching coordinate, due to the near degeneracy of the 2Σ+ and the 2 lowest electronic states at linear geometries. © 1996 John Wiley & Sons, Inc. 相似文献
970.