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921.
M. S. Raghu C. B. Pradeep Kumar K. Yogesh Kumar M. K. Prashanth B. K. Jayanna 《Journal of heterocyclic chemistry》2019,56(7):2046-2051
A novel class of 3‐(4‐chlorophenyl)‐2‐(substituted)quinazolin‐4(3H)‐one derivatives were synthesized, and the structure of synthesized compounds was characterized by IR, 1H NMR, and mass spectroscopy. The newly synthesized compounds ( 4a–g and 6a–g ) were tested for their in vitro cyclooxygenase (COX) inhibition activity. The compounds have inhibitory profile against both COX‐1 and COX‐2, and some of the compounds are found to be selective against COX‐2. The compound 6g showed distinct inhibitory activity on COXs. The synthesized compounds were evaluated for their potential anti‐inflammatory activity as inhibitors of the proinflammatory cytokines IL‐6. Compounds 4d – g showed the highest level of inhibition among all the tested compounds. Thus, our data suggested that these compounds may represent a new class of potent anti‐inflammatory agents. 相似文献
922.
Debabrata Samanta Syamantak Roy Ranjan Sasmal Nilanjana Das Saha Pradeep KR Ranjani Viswanatha Sarit S. Agasti Tapas Kumar Maji 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(15):5062-5066
A solvent responsive dynamic nanoscale metal‐organic framework (NMOF) [Zn( 1 a )(H2O)2] has been devised based on the self‐assembly of ZnII and asymmetric bola‐amphiphilic oligo‐(p‐phenyleneethynylene) (OPE) dicarboxylate linker 1 a having dodecyl and triethyleneglycolmonomethylether (TEG, polar) side chains. In THF solvent, NMOF showed nanovesicular morphology ( NMOF‐1 ) with surface decorated dodecyl chains. In water and methanol, NMOF exhibited inverse‐nanovesicle ( NMOF‐2 ) and nanoscroll ( NMOF‐3 ) morphology, respectively, with surface projected TEG chains. The pre‐formed NMOFs also unveiled reversible solvent responsive transformation of different morphologies. The flexible NMOF showed cyan emission and no cytotoxicity, allowing live cell imaging. Cisplatin (14.4 wt %) and doxorubicin (4.1 wt %) were encapsulated in NMOF‐1 by non‐covalent interactions and, in vitro and in vivo drug release was studied. The drug loaded NMOFs exhibited micromolar cytotoxicity. 相似文献
923.
P.K. Kankar S.P. Harsha Pradeep Kumar Satish C. Sharma 《European Journal of Mechanics - A/Solids》2009,28(4):841-857
Dynamic analysis of a high-speed rotor bearing systems is challenged by their highly nonlinear and complex properties. Hence, an approximate response surface method (RSM) is utilized to analyze the effects of design and operating parameters on the vibration signature of a rotor-bearing system. This paper focuses on accurate performance prediction, which is essential to the design of high performance rotor bearing system. It considers distributed defects such as internal radial clearance and surface waviness of the bearing components. In the mathematical formulation the contacts between the rolling elements and the races are considered as nonlinear springs, whose stiffnesses are obtained by using Hertzian elastic contact deformation theory. The governing differential equations of motion are obtained by using Lagrange's equations. In terms of the feature that the nonlinear bearing forces act on the system, a reduction method and corresponding integration technique is used to increase the numerical stability and decrease computer time for system analysis. Parameters effects are analyzed together and its influence considered with DOE and Surface Response Methodology are used to predict dynamic response of a rotor-bearing system. 相似文献
924.
The first diastereoselective synthesis of
xylo-(2R,3S,4S)-C18-phytosphingosine (1) has been achieved by double stereodifferentiation of enantiomerically enriched terminal olefin 14 using (DHQD)2–PHAL ligand in an asymmetric dihydroxylation with a diastereomeric ratio of 83:17. This phytosphingosine was fully characterized by the physical and spectral data of the corresponding tetraacetate 21. 相似文献
925.
Vibha Saxena Vinay Shirodkar Rajiv Prakash 《Journal of Solid State Electrochemistry》2000,4(4):231-233
The behaviour of a polyindole-based microelectrochemical transistor in aqueous and non-aqueous electrolytes is described.
The polyindole film was grown onto two closely spaced (100 μm) platinum microelectrodes by anodic oxidation of indole (10 mM)
from 0.1 M tetrabutylammonium perchlorate in dichloromethane at 1.1 V vs. Ag/AgCl. The polymerization was carried out for
a sufficiently long time in order to connect both Pt microelectrodes, which operated as a transistor when immersed in an electrolytic
solution. In this transistor, one microelectrode was a “source” and the other a “drain”; the Ag/AgCl wire reference electrode
was used as a “gate”. The drain current (current between source and drain) was modulated by varying the gate potential (potential
between source and gate) at a fixed drain potential (potential between source and drain). The transconductances of the transistor
were estimated as 0.98 mS/cm and 20.6 mS/cm of channel width (separation between two microelectrodes) in aqueous and non-aqueous
solutions, respectively.
Received: 6 April 1999 / Accepted: 24 August 1999 相似文献
926.
Egli M Pallan PS Pattanayek R Wilds CJ Lubini P Minasov G Dobler M Leumann CJ Eschenmoser A 《Journal of the American Chemical Society》2006,128(33):10847-10856
An experimental rationalization of the structure type encountered in DNA and RNA by systematically investigating the chemical and physical properties of alternative nucleic acids has identified systems with a variety of sugar-phosphate backbones that are capable of Watson-Crick base pairing and in some cases cross-pairing with the natural nucleic acids. The earliest among the model systems tested to date, (4' --> 6')-linked oligo(2',3'-dideoxy-beta-d-glucopyranosyl)nucleotides or homo-DNA, shows stable self-pairing, but the pairing rules for the four natural bases are not the same as those in DNA. However, a complete interpretation and understanding of the properties of the hexapyranosyl (4' --> 6') family of nucleic acids has been impeded until now by the lack of detailed 3D-structural data. We have determined the crystal structure of a homo-DNA octamer. It reveals a weakly twisted right-handed duplex with a strong inclination between the hexose-phosphate backbones and base-pair axes, and highly irregular values for helical rise and twist at individual base steps. The structure allows a rationalization of the inability of allo-, altro-, and glucopyranosyl-based oligonucleotides to form stable pairing systems. 相似文献
927.
U. S. Mahabaleshwar K. R. Nagaraju P. N. Vinay Kumar Dumitru Baleanu Giulio Lorenzini 《Continuum Mechanics and Thermodynamics》2017,29(2):559-567
In this paper, we investigate the theoretical analysis for the unsteady magnetohydrodynamic laminar boundary layer flow due to impulsively stretching sheet. The third-order highly nonlinear partial differential equation modeling the unsteady boundary layer flow brought on by an impulsively stretching flat sheet was solved by applying Adomian decomposition method and Pade approximants. The exact analytical solution so obtained is in terms of rapidly converging power series and each of the variants are easily computable. Variations in parameters such as mass transfer (suction/injection) and Chandrasekhar number on the velocity are observed by plotting the graphs. This particular problem is technically sound and has got applications in expulsion process and related process in fluid dynamics problems. 相似文献
928.
Novel liquid crystal materials (LCs) of low temperature range (53°C to 75°C) have been synthesized through a series of chalconyl derivatives consisting of two phenyl rings bonded through a –CH?CH?CO? central bridge to study the effect of molecular structure on LC properties in general and with a focus on molecular rigidity. The novel homologues series (C1 to C18) consists of thirteen homologues with general formula RO?C6H4?CH?CH?CO?C6H4?OC10H21(n) (meta). The C1, C2, C3 homologues are nonliquid crystals (NLC) and the rest of the homologues (C4 to C18) are either monotropic or enantiotropic liquid crystals. C4 to C6 homologues are enantiotropicnematic and the rest of the mesomorphic homologues are (C7 to C18) monotropicsmectic in addition to monotropicnematic character. Transition and melting temperatures including textures of homologues were determined by an optical polarizing (POM) microscopy equipped with a heating stage. Textures of a nematic phase are threaded or Schlieren, and that of the smectic phase are of the type Smectic A or C as judged directly from the heating top of the microscope. Thermal stability for smectic is very poor and of the nematic is (N-I) 69.3°C whose, total mesophase length ranges between 07.0 to 14.0°C at C8 and C4 homologues respectively. 相似文献
929.
930.
Spectroscopic investigations on kidney stones using Fourier transform infrared and X‐ray fluorescence spectrometry
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Kidney stone is the most painful and prevalent urological disorder of the urinary system throughout the world. Thus, analysis of kidney stones is an integral part in the evaluation of patents having stone disease. Spectroscopic investigations of stones provide an idea about the pathogenesis of stones for its better cure and treatment. Hence, the present work targets multispectroscopic investigations on kidney stones using Fourier transform infrared (FTIR) and wave dispersive X‐ray fluorescence (WD‐XRF) spectroscopy which are the most useful analytical methods for the purpose of bio‐medical diagnostics. In the present study, FTIR spectral method is used to investigate the chemical composition and classification of kidney stones. The multicomponents of kidney stones such as calcium oxalate, hydroxyl apatite, phosphates, carbonates, and struvite were investigated and studied. Qualitative and quantitative determination of major and trace elements present in the kidney stones was performed employing WD‐XRF spectroscopy. The wide range of elements determined in the kidney stones were calcium (Ca), magnesium (Mg), phosphorous (P), sodium (Na), potassium (K), chlorine (Cl), sulfur (S), silicon (Si), iodine (I), titanium (Ti), iron (Fe), ruthenium (Ru), zinc (Zn), aluminum (Al), strontium (Sr), nickel (Ni), copper (Cu), and bromine (Br). For the first time, ruthenium was detected in kidney stone samples employing WD‐XRF in very low concentration. Our results revealed that the presence and relative concentrations of trace elements in different kinds of stones are different and depend on the stone types. From the experiments carried out on kidney stones for trace elemental detection, it was found that WD‐XRF is a robust analytical tool that can be useful for the diagnosis of urological disorders. We have also compared our findings with the results reported using XRF technique. The results obtained in the present paper show interesting prospects for FTIR and WD‐XRF spectrometry in nephrolithiasis. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献