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61.
Spin crossover in a series of six cyanide-bridged iron(II) tetranuclear square complexes was analyzed using density functional theory (DFT) methods. As the spin crossover between the low-spin (LS) and high-spin (HS) states can occur only for two of four iron ions, we characterized energetically and structurally the [LS-LS], [HS-LS], and [HS-HS] spin-state isomers. For all studied complexes, the energy of the mixed [HS-LS] spin state does not deviate essentially from the halfway point between the energies of homogeneous spin states, thereby satisfying the conditions for an one-step transition between the [LS-LS] and [HS-HS]. This fact reflects the weak elastic coupling between the environments of transiting centers. The two-step spin transition observed in one complex can appear only due to the crystal packing effects. We also evaluated the strength of exchange coupling between the paramagnetic ions in the [HS-HS] state. 相似文献
62.
Montazer M Lessan F Pajootan E Dadashian F 《Applied biochemistry and biotechnology》2011,165(2):748-759
Trans-glutaminases is known as a cross-linking enzyme for proteins. Wool is a proteinous fiber conventionally is treated through
several processes to obtain the desirable characteristics. Bleaching is also one of the most important processes usually carried
out by using an oxidizing agent in a conventional method. The tensile strength of wool yarns was reduced as a consequence
of oxidative bleaching. Here, with the help of microbial trans-glutaminases (m-TGases), a novel bleaching process was disclosed
in a way to obtain a bleached wool yarn with no significant reduction in the tensile strength. The results confirmed that
the bleached wool yarns with H2O2 could be modified by m-TGases post-treatment. The m-TGases treatment on the bleached wool yarns improved the tensile strength
and whiteness along with the higher alkali resistance. 相似文献
63.
Elmira Solati Maryam Mashayekh Davoud Dorranian 《Applied Physics A: Materials Science & Processing》2013,111(3):689-694
Electrically pumped ultraviolet random lasing was achieved in metal-insulator-semiconductor (MIS) diodes based on ZnO films at room temperature. The ZnO films were grown by plasma assisted molecular beam epitaxy. Two different kinds of insulator layers, SiO x (0<x≤2) and AlO x (0<x≤1.5) were deposited by electron beam evaporation. X-ray diffraction experiments found these oxide layers were amorphous (or microcrystals), and X-ray photoelectron spectroscopy confirmed the Si and Al were fully oxidized. Compared with devices using SiO x as the insulator layer, diodes with evaporated AlO x layers showed a lower working threshold forward current (~20 mA to ~26 mA) and higher emission intensity. Periodic features indicating formation of closed-loop paths were deduced by the power Fourier transform of electroluminescence spectra. The cavity length of both devices increased as forward currents increased, while a larger cavity length was always obtained in the AlO x -involved device under the same working current. The improved performance was attributed to larger hole amount in AlO x layers. These results revealed that evaporated AlO x can serve as good electron blocking and hole supplying layers for hetero-structures. 相似文献
64.
Nedialko B. Dimitrov Dennis P. Michalopoulos David P. Morton Michael V. Nehme Feng Pan Elmira Popova Erich A. Schneider Gregory G. Thoreson 《Annals of Operations Research》2011,187(1):207-228
We describe a model for deploying radiation detectors on a transportation network consisting of two adversaries: a nuclear-material smuggler and an interdictor. The interdictor first installs the detectors. These installations are transparent to the smuggler, and are made under an uncertain threat scenario, which specifies the smuggler??s origin and destination, the nature of the material being smuggled, the manner in which it is shielded, and the mechanism by which the smuggler selects a route. The interdictor??s goal is to minimize the probability the smuggler evades detection. The performance of the detection equipment depends on the material being sensed, geometric attenuation, shielding, cargo and container type, background, time allotted for sensing and a number of other factors. Using a stochastic radiation transport code (MCNPX), we estimate detection probabilities for a specific set of such parameters, and inform the interdiction model with these estimates. 相似文献
65.
Sergey A. Baskakov Yulia V. Baskakova Eugene N. Kabachkov Galina A. Kichigina Pavel P. Kushch Dmitriy P. Kiryukhin Svetlana S. Krasnikova Elmira R. Badamshina Sergey G. Vasilev Timofey A. Soldatenkov Victor N. Vasilets Filipp O. Milovich Alexandre Michtchenko Oksana V. Veselova Vasiliy A. Yakimov Svetlana N. Ivanova Yury M. Shulga 《Molecules (Basel, Switzerland)》2022,27(18)
Cellulose HogC was produced by the modified traditional method with 35% yield from the stem of Sosnovsky hogweed and was characterized by elemental analysis, infrared (IR) spectroscopy, powder X-ray diffractometry, differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). For HogC, the degree of crystallinity (approximately 70%) and the glass transition temperature (105–108 °C) were determined. It was found that the whiteness characteristic in the case of HogC was 92% and this significate was obtained without a bleaching procedure using chlorine-containing reagents. In this paper, the possibility of hydrophobization of HogC films by treatment with radiation-synthesized telomers of tetrafluoroethylene is shown. It was found that the contact angle of the telomer-treated cellulose film surface depended on the properties of the telomers (the chemical nature of the solvent, and the initial concentration of tetrafluoroethylene) and could reach 140 degrees. 相似文献
66.
Elmira Popova 《Operations Research Letters》2004,32(3):283-287
The optimal structure of Bayesian group replacement policies for a parallel system of n items with exponential failure times and random failure parameter is presented. The paper contains a proof of the fact that it is optimal to observe the system only at failure times. For the case of two items operating in parallel the exact form of the policy is derived. 相似文献
67.
Damir A. Safin Dr. Felix D. Sokolov Sergey V. Baranov Łukasz Szyrwiel Maria G. Babashkina Elmira R. Shakirova F. Ekkehardt Hahn Henryk Kozlowski 《无机化学与普通化学杂志》2008,634(5):835-838
Reaction of the potassium salt of N‐diisopropoxyphosphinyl‐p‐bromothiobenzamide p‐BrC6H4C(S)NHP(O)(OiPr)2 ( HL ) with Ni(NO3)2 in aqueous EtOH leads to complex of formula [Ni(HL‐O)2(L‐O,S)2] ( 1 ). The structure of 1 was investigated by single crystal X‐ray diffraction analysis, IR, 1H and 31P{1H} NMR spectroscopy, MALDI and microanalysis. The nickel(II) ion in 1 has a tetragonal‐bipyramidal environment, (Oax)2(Oeq)2(Seq)2, with two neutral ligand molecules coordinated in axial positions through the oxygen atoms of the P=O groups. The equatorial plane of bipyramide is formed by two anionic ligands involving 1,5‐O,S‐coordination mode. The chelating ligands are bound in trans configuration. 相似文献
68.
Reaction of 2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione (Meldrum’s acid) with various solid aldehydes in the presence of cyanogen bromide and solid sodium ethoxide (EtONa) leads to the selective and efficient formation of bis‐spiro cyclopropanes based on Meldrum’s acid at the range of 0 °C to room temperature. The products were obtained in good to excellent yields. Structure elucidation is carried out by 1H NMR, 13C NMR, FT‐IR spectroscopy, mass analyses and X‐ray crystallography techniques. A possible mechanism for the formation of products is also discussed under solvent‐free condition. 相似文献
69.
Samvel N. Sirakanyan Athina Geronikaki Viktor G. Kartsev Elmira K. Hakobyan Anush A. Hovakimyan 《合成通讯》2019,49(10):1262-1276
Taking into account previously obtained biological results on some polyheterocyclic compounds (containing different heteroatoms) and in particular on several 8-amino-5-isopropyl-2,2-dimethyl-10-(methylthio)-1,4-dihydro-2H-pyrano[4’’,3’’:4’,5’]pyrido[3’,2’:4,5]thieno[3,2-d]pyrimidines Ia-v we have carried out the synthesis of twentyone 8-amino-5-isobutyl-2,2-dimethyl-10-(methylthio)-1,4-dihydro-2H-pyrano[4’’,3’’:4’,5’]pyrido[3’,2’:4,5]thieno[3,2-d]pyrimidines 6. Therefore we have slightly modified the structure of the previously studied I introducing at C-5 an isobutyl group instead of the previously examined isopropyl ones in order to see if this variation (changing a little the lipophilicity) will affect the biological activity. Furthermore thieno[3,2-d]pyrimidine-8-thione 7 and their S-alkylated 8 were synthesized. Finally by alkylation of 5-isobutyl-2,2-dimethyl-10-thioxo-1,4,10,11-tetrahydro-2H-pyrano[4'',3'':4',5']pyrido[3',2':4,5]thieno[3,2-d]pyrimidin-8(9H)-one 3 with alkyl dichlorides (bifunctional reagents) we realized the cyclization of a thiazole or thiazine ring on the [b] side of the pyrimidine ring with formation of the new condensed pentaheterocyclic systems: pyrano[4'',3'':4',5']pyrido[3',2':4,5]thieno[3,2-d][1,3]thiazolo[3,2-a]pyrimidin-8-one 11 and pyrano[4''',3''':4'',5'']pyrido[3'',2'':4',5']thieno[3',2':4,5]pyrimido[2,1-b][1,3]thiazin-8-one 12. It was found that some of the synthesized compounds showed interesting antimicrobial activity (by agar diffusion method) against some gram-positive and gram-negative bacilli strains. 相似文献
70.
Andrei V. Churakov Sergey S. Karlov Elmira Kh. Lermontova Galina S. Zaitseva Judith A. K. Howard 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(12):o761-o762
The title compound, C24H17F10N3O2, exhibits intramolecular N—H...O hydrogen bonding, as well as intramolecular Ar...ArF face‐to‐face interactions. The molecules are linked together by N—H...F—C hydrogen bonds, forming chains parallel to the a axis. Adjacent symmetry‐related chains are combined in double zipper‐like ribbons by parallel ArF...ArF offset π‐stacking interactions. 相似文献