Search

Thiazolo[3,2-a]pyrimidines namely ethyl 2-acetyl-5-(2-fluorophenyl)-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate 3a, ethyl 2-acetyl-5-(3-fluorophenyl)-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate 3b, and ethyl 2-acetyl-5-(4-fluorophenyl)-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate 3c were obtained by one pot synthesis using substituted 3,4 dihydropyrimidine2-thione (1a–1c) and 3-chloro-2,4-pentanedione in ethanol and characterized by single-crystal X-ray diffraction. The variation in the position of fluorine atom on pyrimidine nucleus and insight into the self-assembly of compounds with varied types of non-covalent interactions has great influence on crystal packing. [ABSTRACT FROM AUTHOR]

Assuming plane strain conditions and taking phase transformations into account, finite element analysis was carried out using a bead-by-bead deposition model as well as two different lumped models. The effects of post-weld heat treatment at 600 °C were also studied. Predicted residual stresses were verified using X-ray diffraction method. While both bead-by-bead and lumped models were found to overestimate the maximum residual stress in as-welded condition, the latter facilitated a safer upper-bound estimate of the residual stress. The net tensile stress in the weld metal was found to decrease as a result of solid-state transformation of austenite to ferrite. Further, a significant part of stress relief was found to occur in the first half hour of the holding time during post-weld heat treatment. A formula was developed for estimating the maximum residual stress in post-weld heat treated condition. [ABSTRACT FROM AUTHOR]

Trivalent Al3+-doped samples of magnetite (Alx ${\mathrm {Fe}}_{3-x}\text{O}$ 4, $0.01\le x \le1.0$) were produced by wet chemical method. The X-ray diffraction studies confirmed the formation of a single-phase inverse spinel-type structure. Particles having spherical morphology and size range lying between 4 and 25 nm were observed during transmission electron microscopic investigation. Magnetic measurement displayed increase in saturation magnetization with a maximum value of ~62 $\text{A}\cdot \text{m}$ 2/kg for $x =0.1$ , and thereafter, it started decreasing with increased concentration of Al. The temperature during magnetic hyperthermia got stabilized near therapeutic range (~315 K) for the samples such as $x =0.01$ , 0.5, 0.7, and 1.0 at various external alternating current magnetic fields. [ABSTRACT FROM AUTHOR]

Cucurbiturils are magnificent macrocycles that are used as precise molecules for the fabrication of supramolecular chemotherapeutic agents through host-guest molecular recognition. In the present work, the host-guest complex of cucurbit[6]uril (CB[6]) with 5-fluorouracil (Flu, an anticancer drug) is synthesized and its structural study was carried out using UV, XRD, and TG/DTA techniques. The UV-Vis spectrum of the inclusion complex exhibited maximum absorbance with a blue shift at 302 nm whereas the maximum absorbance for free CB[6] was observed at 318 nm. This notable shift in wavelength proves the formation of the inclusion complex of CB[6] with fluorouracil. The host-guest complex of fluorouracil with CB[6] shows sharp endothermic peaks at 403.30C with a heat flow of -0.5 mW/mg the peak covers partially an area of 528.2 J/g, The large variations observed in the DSC curves of the complex compared with free host CB[6] confirm the formation of a stable host-guest complex. The XRD pattern of the host-guest complex is different from the parent compound and this reaffirms the formation of host-guest complex. The cytotoxic effect of 5-fluorouracil and the host-guest complex of CB[6] with fluorouracil on KB cells was determined by MTT assay and the cytotoxicity of anticancer drug Flu towards cancer cells significantly increases by encapsulating 5-fluorouracil into the hydrophobic cavity of CB[6], The ROS generation study was carried out by measurement of intracellular ROS using fluorescent and chemiluminescent probe. The ROS generation of anticancer drugs against cancer cells is significantly increased by encapsulating 5-fluorouracil into the hydrophobic cavity of CB[6], The inclusion complex of cucurbituril with fluorouracil treatment in KB cells showed higher anticancer potential than fluorouracil treatment in KB cells when compared to the control. The IC50 value of 5-flurouracil was found to be higher compared to the inclusion complex of cucurbituril with fluorouracil. The interesting results obtained, might open new avenues for the use of CB[6] host-guest complexes in anticancer and drug delivery studies. [ABSTRACT FROM AUTHOR]

Samarium modified SrBi4-xSmxTi4O15 (x = 0, 0.13, 0.43 and 0.78) ferroelectric ceramics of Aurivillius family were prepared by conventional solid state reaction method. X-ray diffraction studies confirm the formation of a single-phase. Microstructural images show randomly oriented palate-like structure. Broad dielectric peaks were found to obey the modified Curie-Weiss law. The overall inherent ferroelectric nature was explained on the basis of the Avrami model. Furthermore, with increasing the Sm3+ content, the grain morphology and diffusive parameters have shown a comprehending impact on the ferroelectric (hysteresis) behavior. [ABSTRACT FROM AUTHOR]

In the present study, lead-free piezoelectric (1-x)[(Bi 0.96 La 0.04 ) 0.5 Na 0.5 TiO 3 ]-(x)[Ba 0.90 Ca 0.10 TiO 3 ] ceramics with x ≤ 0.20 have been prepared at optimum temperature (950°C–1050 °C) by employing semi-wet technique. The effect of Ba 0.90 Ca 0.10 TiO 3 (BCT) content on the phase formation, surface morphology, dielectric and piezoelectric properties is systematically investigated and characterized by X-ray diffraction (XRD), Raman Spectroscopy, Field emission Scanning electron micrographs (FE-SEM), Impedance analyzer. XRD analysis shows phase transformation from rhombhohedral to tetragonal with the addition of BCT and the average grain size decreases with BCT content, x. Temperature dependent dielectric behavior exhibits two phase transitions, i.e. depolarization temperature; T d and phase transition temperature; T m . The phase transitions; T m tends to diffuse with increasing x and exhibited a broad frequency dependent maximum upto x ≤ 12. Optimum piezoelectric and dielectric properties (i.e., d 33 = 165 pC/N, k p = 39%, k t = 47% and k 33 = 57%, ε r = 1585, tan δ = 0.07) in the studied system have been obtained. [ABSTRACT FROM AUTHOR]

NiMnZnFeO ( x = 0.0-0.6) samples were synthesized using a combustion technique involving a mixture of hexamine and metal nitrate. XRD measurements confirmed the single-phase formation. The lattice parameters were found to increase gradually with increasing Mn substitution. The peak broadening observed for these ferrites indicates their nanocrystalline nature. FTIR spectra display two absorption bands which are characteristics of M-O stretching in tetrahedral and octahedral sites in the spinel lattice. SEM observations show that the particles occur as loose agglomerates. Lower DC resistivity values in the range of 10 to 10 Ωcm observed at room temperature suggests the protonic conductivity due to moisture trapped inside the pores. The resistivity was found to decrease with increasing Mn substitution at higher temperatures. AC susceptibility studies reveal the presence of clusters of both superparamagnetic and single-domain particles. Curie temperatures were found to decrease with increasing Mn concentration. The low dielectric losses of about 10 in the higher frequency region were observed. [ABSTRACT FROM AUTHOR]

The ultrathin channel in nanotube is an exciting host to encapsulate sub-nanometer size guest spices. The dynamics of confined C 60 s inside the nanoscale host tube have been investigated by various stimuli like e-beam irradiation, Ar-ion laser and Cu K α X-ray. It has been disclosed that the accelerating voltage of TEM higher than the threshold energies of the ballistic knockoff in carbon atoms can be used to understand the rotation of host species in the confined geometry. The radial breathing Raman mode of host SWCNTs has been studied to insight into the enhanced mobility of guest C 60 s at higher temperatures in the confined tube geometry of nanopeapod. We have highlighted the role of temperature as a function of kinetic energy of the confined C 60 s in SWCNTs and which leads to the reduction of stress in host–guest complex. The temperature-dependent XRD has been used to study the mobilities of C 60 molecules adsorbed onto the SWCNTs to move along the tube walls until they detect an opening to infuse in the confined space [ABSTRACT FROM AUTHOR]