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141.
We investigate the interplay of classical degeneracy and quantum dynamics in a range of periodic frustrated transverse field Ising systems at zero temperature. We find that such dynamics can lead to unusual ordered phases and phase transitions or to a quantum spin liquid (cooperative paramagnetic) phase as in the triangular and kagome lattice antiferromagnets, respectively. For the latter, we further predict passage to a bond-ordered phase followed by a critical phase as the field is tilted. These systems also provide exact realizations of quantum dimer models introduced in studies of high temperature superconductivity. 相似文献
142.
143.
Shyamalee GogoiMandakini Dutta Junali GogoiRomesh Chandra Boruah 《Tetrahedron letters》2011,52(7):813-816
A microwave-promoted and base-catalyzed synthesis of cycl[3.2.2]azines is accomplished in water via a three-component reaction (3-CR) of 2-picoline, α-bromoacetophenone and alkyne. The extension of the methodology to the synthesis of steroidal and carbocyclic cycl[3.2.2]azine is also reported. 相似文献
144.
Kalyanmoy Jana Somnath Das Tithi Maity Maidul Hossain Subhas Chandra Debnath 《Journal of Coordination Chemistry》2018,71(10):1497-1509
A new Co(II) complex of general formula [Co(L)2] has been synthesized from a NNO tridentate Schiff base ligand, 2-[(piperidin-2-ylmethylimino)-methyl]-phenol (L). The title complex is characterized by elemental, spectroscopic, antibacterial, and single crystal X-ray structural studies. X-Ray crystallography reveals that the complex shows a distorted octahedral geometry around the Co(II) ion. The complex was tested against several bacteria and shows good antibacterial activities against almost all of the bacteria. The interactions of the title complex with calf thymus deoxyribonucleic acid (CT-DNA) have been investigated by electronic absorption and fluorescence spectroscopy, showing that the complex interacts with CT-DNA via partial intercalation. Thermogravimetric analysis (TGA) of the complex has also been reported and the result shows that the complex is thermally stable up to 134 °C. 相似文献
145.
Chandra Kanta Ghosh Anirban Ray Amarendra Patra 《Journal of heterocyclic chemistry》2001,38(6):1459-1463
The title aldehyde 1 in the presence of ammonia gives the pyridine derivatives 9‐11 respectively with acetylacetone, diethyl malonate and ethyl cyanoacetate, and ethyl (or methyl)‐l‐benzopyrano[4,3‐b]pyri‐dine‐3‐carboxylate 22 (or 23 ) with ethyl (or methyl) acetoacetate. Acetylacetone pretreated with ammonia condenses with 1 giving the fused pyridine 24 . Ammonia converts the ester 6 to the pyridine 13 or 14 . Chromic acid oxidation of 22 and 23 affords the coumarinopyridines 25 and 26 , respectively. 相似文献
146.
In an attempt to study the scope of a theorem due to Pati, the authors have established that φ(t) logK|t∈B
u
V in (0,π)⟹ΣA
n
(x) is |C, 0,β| forβ>1, at the pointt = x. 相似文献
147.
M. Chandra Sekhar P. Kondaiah S.V. Jagadeesh Chandra G. Mohan Rao S. Uthanna 《Applied Surface Science》2011,258(5):1789
Titanium dioxide (TiO2) films have been deposited on glass and p-silicon (1 0 0) substrates by DC magnetron sputtering technique to investigate their structural, electrical and optical properties. The surface composition of the TiO2 films has been analyzed by X-ray photoelectron spectroscopy. The TiO2 films formed on unbiased substrates were amorphous. Application of negative bias voltage to the substrate transformed the amorphous TiO2 into polycrystalline as confirmed by Raman spectroscopic studies. Thin film capacitors with configuration of Al/TiO2/p-Si have been fabricated. The leakage current density of unbiased films was 1 × 10−6 A/cm2 at a gate bias voltage of 1.5 V and it was decreased to 1.41 × 10−7 A/cm2 with the increase of substrate bias voltage to −150 V owing to the increase in thickness of interfacial layer of SiO2. Dielectric properties and AC electrical conductivity of the films were studied at various frequencies for unbiased and biased at −150 V. The capacitance at 1 MHz for unbiased films was 2.42 × 10−10 F and it increased to 5.8 × 10−10 F in the films formed at substrate bias voltage of −150 V. Dielectric constant of TiO2 films were calculated from capacitance–voltage measurements at 1 MHz frequency. The dielectric constant of unbiased films was 6.2 while those formed at −150 V it increased to 19. The optical band gap of the films decreased from 3.50 to 3.42 eV with the increase of substrate bias voltage from 0 to −150 V. 相似文献
148.
Ohne Zusammenfassung 相似文献
149.
The electronic charge distribution in tetragonal closed packed (tcp) metal is approximated by a collection of spherical charge
clouds situated midway between the ions. The anisotropy of the charge distribution is parameterized in terms of a charge shift
δ derivable from the lattice parameters and the elastic coefficients of the metal. The electric field gradient (EFG) in the
metal can be obtained through lattice summations over the charges. Numerical calculations are made to obtain the EFG in pure
indium and indium-based dilute impurity alloys. Fairly good agreement with the experiments is achieved. 相似文献
150.
Summary Polar heteroatomic concentrates were separated from deasphalted oils and asphalts of indigenous crudes by various separation techniques. Conditions have been standardized for its separation using Fuller's earth as adsorbent, and data is compared with those obtained by the techniques reported in the literature. Semiquantitative estimates of phenols, pyrrols, carboxylic acids and amides in the concentrates were also made by IR spectrometry. 相似文献