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Clemens Schmetterer Divakar Rajamohan Herta Silvia Effenberger Hans Flandorfer 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(10):i65-i67
Dinickel ditin zinc, Ni2Sn2Zn, crystallizes in the cubic space group , with a lattice parameter of a = 8.845 (1) Å and with all atoms occupying special positions. The crystal structure exhibits pronounced similarities with that of the quaternary compound Ni5.20Sn8.7Zn4.16Cu1.04. It shares structural features with other compounds in the Ni–Sn–Zn system, such as Ni5Sn4Zn and Ni3Sn2. 相似文献
13.
Marta Snchez Isabel Urea-Vacas Elena Gonzlez-Burgos Pradeep Kumar Divakar Maria Pilar Gmez-Serranillos 《Molecules (Basel, Switzerland)》2022,27(15)
The genus Cetraria s. str. (Parmeliaceae family, Cetrarioid clade) consists of 15 species of mostly erect brown or greenish yellow fruticose or subfoliose thallus. These Cetraria species have a cosmopolitan distribution, being primarily located in the Northern Hemisphere, in North America and in the Eurasia area. Phytochemical analysis has demonstrated the presence of dibenzofuran derivatives (usnic acid), depsidones (fumarprotocetraric and protocetraric acids) and fatty acids (lichesterinic and protolichesterinic acids). The species of Cetraria, and more particularly Cetraria islandica, has been widely employed in folk medicine for the treatment of digestive and respiratory diseases as decoctions, tinctures, aqueous extract, and infusions. Moreover, Cetraria islandica has had an important nutritional and cosmetic value. These traditional uses have been validated in in vitro and in vivo pharmacological studies. Additionally, new therapeutic activities are being investigated, such as antioxidant, immunomodulatory, cytotoxic, genotoxic and antigenotoxic. Among all Cetraria species, the most investigated by far has been Cetraria islandica, followed by Cetraria pinastri and Cetraria aculeata. The aim of the current review is to update all the knowledge about the genus Cetraria covering aspects that include taxonomy and phylogeny, morphology and distribution, ecological and environmental interest, phytochemistry, traditional uses and pharmacological properties. 相似文献
14.
Palaniswami Ravi Soundar Divakar 《Journal of inclusion phenomena and macrocyclic chemistry》2000,38(1-4):323-336
Sterically controlled styrene-acrylonitrile (SAN)copolymers were prepared by inclusion polymerizationusing molar equivalents of -cyclodextrin(-CD) and its derivative. Comonomercompositions, reactivity ratios, monomer sequence andaverage styrene and acrylonitrile sequence lengthswere determined using 13C NMR spectroscopy. Themolecular weight of the polymers prepared increasedwith decreasing -CD concentration, but wasfound to be less than the control. With increase inthe styrene: -CD ratios the averageacrylonitrile sequence length and run number of thepolymers increased. The glass transition temperature(g) also increased along with the meltingtemperature (m) of the polymers at higherstyrene:-CD ratios. 相似文献
15.
Palaniswamy Ravi Soundar Divakar 《Journal of inclusion phenomena and macrocyclic chemistry》2001,39(1-2):27-33
Stereoselective hydrogenation of thymol over Rh/alumina in the presence of various equivalents of -cyclodextrin (-CD) and itsderivatives in the solid state was studied. Hydrogenation of thymol in the absence of -CD gave 76.8% epimeric alcohols with a menthol/neomenthol (M/N) ratio of 5.6 and an alcohol/ketone ratio of 4.5, whereas the presence of 0.1 equivalent (to thymol) of -CD gave rise to 94.6% of epimeric alcohols with a M/N ratio of 6.3 and an alcohol/ketone ratio of 45.4. The effect of -cyclodextrin and its derivatives on the modification of the yield and the proportion of epimeric alcohols formed were found to be the salient features of this investigation. Inclusion complexation of thymol by -CD studied by UV-Visible spectroscopyindicated a 2:1 stoichiometry ofthymol: -CD complex with a binding constant value of 480 ±40 M-2. 相似文献
16.
Soundar Divakar 《Journal of inclusion phenomena and macrocyclic chemistry》1993,15(4):305-316
The structure of the inclusion complex formed between naringin (naringenin-7-O--neohesperidoside) and-cyclodextrin (BCD) was studied in detail by UV and NMR spectroscopic techniques and potentiometry. A binding constant value of 1016±150M–1 was arrived at from UV studies. Potentiometric studies showed that pK values of 4-OH and 5-OH were affected by and-cyclodextrins. One-dimensional difference NOE and spin-lattice relaxation time (T
1) measurements indicated that the aglycone protion was affected more than the neohesperidoside portion. TheT
1 values analysed for local motions indicated that
c
values of complexed naringin was higher than that of free naringin. The internal rotation calculated for different groups showed
i
values for the phenolic and dihydrobenzopyran portion decrease by a factor of 2. Also a value of 0.12–0.17 observed for the aglycone portion indicated that the coupling between guest and host is weak. All the studies have shown that the disposition in which the phenol group at 2 is inside the BCD cavity with 4-keto and 5-OH hydrogen bonded to the secondary hydroxyl groups at the rim of the wider end of the BCD cavity is the most probable one. 相似文献
17.
18.
A Fast and Facile Fabrication of PTFE Based Superhydrophobic and Ultra Wideband Angle Insensitive Anti‐Reflection Coatings (Phys. Status Solidi RRL 6/2018)
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19.
Zotkin DN Duraiswami R Grassi E Gumerov NA 《The Journal of the Acoustical Society of America》2006,120(4):2202-2215
An efficient method for head-related transfer function (HRTF) measurement is presented. By applying the acoustical principle of reciprocity, one can swap the speaker and the microphone positions in the traditional (direct) HRTF measurement setup, that is, insert a microspeaker into the subject's ear and position several microphones around the subject, enabling simultaneous HRTF acquisition at all microphone positions. The setup used for reciprocal HRTF measurement is described, and the obtained HRTFs are compared with the analytical solution for a sound-hard sphere and with KEMAR manikin HRTF obtained by the direct method. The reciprocally measured sphere HRTF agrees well with the analytical solution. The reciprocally measured and the directly measured KEMAR HRTFs are not exactly identical but agree well in spectrum shape and feature positions. To evaluate if the observed differences are significant, an auditory localization model based on work by J. C. Middlebrooks [J. Acoust. Soc. Am. 92, 2607-2624 (1992)] was used to predict where a virtual sound source synthesized with the reciprocally measured HRTF would be localized if the directly measured HRTF were used for the localization. It was found that the predicted localization direction generally lies close to the measurement direction, indicating that the HRTFs obtained via the two methods are in good agreement. 相似文献
20.
Ramaswamy Ravichandran Soundar Divakar 《Journal of inclusion phenomena and macrocyclic chemistry》1993,16(3):201-208
Studies on the effect of-cyclodextrin (BCD) and its derivatives on the selectivity in hydroxymethylation of guaiacol by formaldehyde was carried out. Fairly high selectivity with respect to isovanillyl alcohol formation was achieved. Significantly, the selectivity-enhancing effects of 2,6-di-O-methyl-BCD was much larger, giving rise to 22% more of isovanillyl alcohol formation than BCD and its polymer. UV, fluorescence,1H-NMR spectroscopic and potentiometric studies were also carried out to determine the orientation of guaiacol inside the BCD cavity. 相似文献