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1.
Vishal A. Mahajan 《Tetrahedron》2006,62(6):1258-1272
A short synthetic strategy for synthesis of lignan analogues involving 5-methylene-4-substituted-2(5H)-furanones as the key intermediates has been developed. Various lignans including the natural product solafuranone and analogues of dihydrotaiwanin C and deoxydehydropodophyllotoxin were synthesized in good yields. 相似文献
2.
Raj Gandhi Kamales Kar S. Uma Sankar Abhijit Bandyopadhyay Rahul Basu Pijushpani Bhattacharjee Biswajoy Brahmachari Debrupa Chakraborti M. Chaudhury J. Chaudhury Sandhya Choubey E. J. Chun Atri Desmukhya Anindya Datta Gautam Dutta Sukanta Dutta Anjan Giri Sourendu Gupta Srubabati Goswami Namit Mahajan H. S. Mani A. Mukherjee Biswarup Mukhopadhyaya S. N. Nayak M. Randhawa Subhendu Rakshit Asim K. Ray Amitava Raychaudhuri D. P. Roy Probir Roy Suryadeep Roy Shiv Sethi G. Sigl Arunansu Sil N. Nimai Singh Mark Vagins Urjit Yagnik 《Pramana》2003,60(2):405-409
This is the report of neutrino and astroparticle physics working group at WHEPP-7. Discussions and work on CP violation in
long baseline neutrino experiments, ultra high energy neutrinos, supernova neutrinos and water Cerenkov detectors are discussed. 相似文献
3.
Dieter Seebach Laurent Schaeffer Franois Gessier Pascal Bindschdler Corinna Jger Delphine Josien Sascha Kopp Grald Lelais YogeshR. Mahajan Peter Micuch Radovan Sebesta BerndW. Schweizer 《Helvetica chimica acta》2003,86(6):1852-1861
Multigram amounts of suitably protected β2‐amino acids with 17 of the 20 proteinogenic side chains are prepared by diastereoselective reactions of Li, B, or Ti enolates of the corresponding 3‐acyl‐4‐isopropyl‐5,5‐diphenyloxazolidin‐2‐ones (acyl‐DIOZ; 1 ) with appropriate electrophiles (amidomethylation, hydroxyalkylation, (benzyloxycarbonyl)methylation) in yields of 55–90% and with diastereoselectivities of 80 to >97% (Scheme). The primary products 2 – 8 thus obtained are converted to protected β2‐amino acids by standard procedures (Table 1). Many of the DIOZ derivatives are highly crystalline compounds (31 X‐ray crystal structures in Table 2). The chiral auxiliary DIOZ, readily prepared in either enantiomeric form, is recovered with high yield. 相似文献
4.
5.
D. R. Prabhu G. R. Mahajan G. M. Nair 《Journal of Radioanalytical and Nuclear Chemistry》1997,224(1-2):113-117
The extraction of uranium(VI) and plutonium(IV) from nitric acid into n-dodecane was studied using two isomeric branched alkyl amides, di(2-ethyl hexyl) butyramide (DEHBA) and di(2-ethyl hexyl) isobutyramide (DEHIBA). The extraction ratios of Pu(IV) at relatively high acidities were higher than the corresponding values for U(VI) in the case of DEHBA. However, with DEHIBA the values for Pu(IV) were negligibly small. Pu(IV) was found to be extracted as trisolvate by DEHBA and as disolvate by DEHIBA. U(VI) was extracted by both the amides. From the study of the extraction reactions at different temperatures, it was shown that all the reactions in the present investigation were enthalpy favoured and entropy disfavoured. Separation of Pu(IV) from bulk of U(VI) was feasible. However, the purity of the separated plutonium was not satisfactory in batch extraction studies. 相似文献
6.
Garcia CB Zhang Y Mahajan S DiSalvo F Wiesner U 《Journal of the American Chemical Society》2003,125(44):13310-13311
In the present study poly(isoprene-block-ethylene oxide), PI-b-PEO, block copolymers are used to structure iron oxide and silica precursors into reverse mesophases, which upon dissolution of the organic matrix lead to well-defined nanoparticles of spheres, cylinders, and plates based on the original structure of the mesophase prepared. The hybrid mesophases with sphere, cylinder, and lamellar morphologies containing the inorganic components in the minority phases are characterized through a combination of small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and electron energy loss spectroscopy (EELS). After heat treatments the respective nanoparticles on mica surfaces are characterized by scanning force microscopy (SFM). X-ray diffraction (XRD) and superconducting quantum interference device (SQUID) magnetometer measurements are performed to demonstrate that the heat treatment leads to the formation of a magnetic gamma-Fe2O3 crystalline phase within the amorphous aluminosilicate. The results pave the way to functional, i.e., magnetic nanoparticles where the size, shape, and iron oxide concentration can be controlled opening a range of possible applications. 相似文献
7.
B. Pandey M. P. Mahajan R. K. Tikare M. Muneer N. P. Rath P. V. Kamat M. V. George 《Research on Chemical Intermediates》1991,15(3):271-291
The reaction of tetracyclone (1) with potassium in THF gave a mixture of benzoic acid (4), tetraphenylfuran (5) and cis-1,2-dibenzoylstilbene (6). The reaction of 1 with potassium in oxygen-saturated THF gave a mixture of 2-hydroxy-2,4,5-triphenyl-3(2H)furanone (3), 4, 5 and 6, whereas the reaction of 1 with potassium superoxide gave a moderate yield of 3,4,5,6-tetraphenyl-2-pyrartone (7), besides 3, 4, 5, and 6. The reaction of tetraphenylfuran (5) itself with potassium in THF gave a mixture of 6, 1,2,3,4-tetraphenylbutan-1-one (9), 2,3-diphenyl-1-indenone (10) and 2,3-epoxy-4-hydroxy-2,3,4-tnphenyltetralone-l (11), whereas practically no reaction occurred on treatment of 5 with potassium superoxide. Treatment of 10 with potassium in THF, however, gave a mixture of 4, dibenzo[a,c]-13-fluorenone (13), 2,3-diphenyl-2-hydroxyl-1-indanone (14) and 2,3-diphenylbenzofuran (15). A similar mixture of products consisting of 4, 13, 14 and 15 was obtained when the reaction of 10 with potassium was carried out in oxygen-saturated THF or when 10 was treated with potassium superoxide. Treatment of 2,3-diphenyl-2,3-epoxy-1-indanone (16) with potassium on the other hand, gave 10 in excellent yield. Cyclic voltammetric studies have been carried out to measure the reduction potentials of 1, 5, 10 and 16 in the generation of their radical anions. The radical anions of 1, 5, 10 and 16 were also generated pulse radiolytically in methanol and their spectra showed absorption maxima in the region 320–380 nm. 相似文献
8.
The Aharonov-Bohm effect (ABE) for steady magnetic fields is a well known phenomenon. However, if the current in the infinite solenoid that creates the magnetic field is time-dependent, that is in the presence of both magnetic and electric fields, there is no agreement whether the effect would be present. In this note, we try to investigate time varying ABE by a direct calculation in a set-up with a weak time dependent magnetic field. We find that the electric field arising out of the time-varying magnetic field in the path of the electrons does not enter the action integral but only changes the path of the electron from the source to the slits and then on to the detector. We find a frequency dependent AB phase shift. At low frequencies the result smoothly approaches the one for a constant field as the frequency tends towards zero. On the other hand, for high frequencies such that the AB-phase induced in the path of the wave packet oscillates rapidly, the net effect will be very small which is borne out by our results. 相似文献
9.
Amit C. Patel Dharmesh H. Mahajan Kishor H. Chikhalia 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):368-376
A new series of 2-(coumarin-3-yl)-5-mercapto-1,3,4-oxadiazoles based on various aryl thiourea/ureas incorporating a 1,3,5-s-triazine moiety is reported. The components of this series have been obtained by the reaction of cyanuric chloride (1) with 2-(coumarin-3-yl)-5-mercapto-1,3,4-oxadiazole (2). The prepared 2-{(coumarin-3-yl-1,3,4-oxadiazolyl)-5-thio}-4,6-dichloro-s-triazine (3) was subsequently treated with morpholine (4) to form 2-{(coumarin-3-yl-1,3,4-oxadiazolyl)-5-thio}-4-(morpholino)-6-chloro-s-triazine (5). This was further treated with various substituted aryl urea/thioureas (6a–k/7a–k) to afford the title compounds 8a–k and 9a–k, which were and tested for their antibacterial activity (MIC) against different microorganisms. The structures of the novel synthesized compound have been established on the basis of 1H NMR and FT-IR data together with elemental analysis. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
10.
Resource optimization is a very important issue related with restoration in optical networks. In the proactive restoration, backup lightpaths are established along with the primary light paths. In this paper, we have proposed a strategy for resource optimization, which works with proactive restoration. The performance of the proposed strategy is evaluated by applying on the sample network. 相似文献