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381.
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383.
At ambient conditions the acoustic losses within the fluid are two orders of magnitude smaller than those occurring at a duct wall, so that they are commonly neglected in duct acoustics. Recent measurements revealed an increasing sound attenuation at elevated pressure and temperature, which cannot be justified by the viscothermal losses at the wall alone. In the first part, this paper compiles available models to pursue a comprehensive treatment of the sound attenuation in a duct at elevated pressure and temperature. The second part presents an experimental study of the attenuation. The measurements have been performed at the Hot Acoustic Test Rig, where pressure and temperature can be independently adjusted from their ambient values up to 1100 kPa and 823 K, respectively. The theoretical prediction of the total losses matches the experimental data, thus confirming that the losses within the fluid cannot be neglected in ducts at elevated pressure and temperature. 相似文献
384.
The present investigation concerns the analysis of the influence of short range orientational correlation on the thermodynamic properties of discotic-nematic liquid crystals. Two-site cluster approximation is applied to the orientational molecular coordinates to include the short range orientational correlation. The role of short range orientational order, dispersion interaction, molecular length-to-width ratio and pressure on the thermodynamic and orientational behaviour of discotic nematogens close to the discotic-nematic to isotropic transition are analysed. It is observed that the short range orientational order has a strong influence on the thermodynamic properties and that the transition properties of both the calamitic and discotic mesogens exhibit quite similar behaviour. 相似文献
385.
Kaustab Ghosh Moumita Maiti Susanta Lahiri 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):1049-1054
The room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] has various applications in the separation of a range of metal ions replacing volatile and toxic traditional organic solvents in liquid–liquid extraction systems. In this study, the RTIL [C4mim][PF6] was used to separate no-carrier-added (NCA) 109Cd from α-particle irradiated Ag target. A natural Ag foil was bombarded by 30 MeV α-particles to produce 109Cd. After the decay of all co-produced short-lived products, NCA 109Cd was separated from the bulk Ag using [C4mim][PF6] as extractant from HNO3 medium. Ammoniumpyrrolidine dithiocarbamate (APDC) was used as a complexing agent. At the optimum condition, 3 M HNO3, 0.01 M APDC in presence of [C4mim][PF6], ~99 % bulk Ag was extracted to the IL phase, leaving NCA 109Cd in the aqueous phase. The amount of Ag became negligibly small after re-extraction in the same condition. The ionic liquid was recovered by washing it with 1 M HCl. 相似文献
386.
Electrodeposition of silicon from three different ionic liquids: possible influence of the anion on the deposition process 总被引:1,自引:0,他引:1
G. Pulletikurthi A. Lahiri T. Carstens N. Borisenko S. Zein El Abedin F. Endres 《Journal of Solid State Electrochemistry》2013,17(11):2823-2832
The electrodeposition of silicon was investigated from three different ionic liquids with the cation 1-butyl-1-methylpyrrolidinium ([Py1,4]+) and three different anions, namely, trifluoromethylsulfonate (TfO?), bis(trifluoromethylsulfonyl)amide (TFSA?) and tris(pentafluoroethyl)-trifluorophosphate (FAP?) at room temperature and at 100 °C, respectively. The electrodeposition was performed on gold and on copper substrates. Cyclic voltammetry was used to evaluate the possible influence of anions on the deposition process. In situ STM studies were also carried out to examine the interfacial behaviour of the SiCl4/[Py1,4]TFSA and SiCl4/[Py1,4]FAP on Au(111) at room temperature. In situ STM measurements revealed that an underpotential deposition of Si in [Py1,4]FAP occurred on Au (111) at ~ -0.5 V (vs. Fc/Fc+). In comparison, only adsorption of ionic liquid and gold surface reconstruction was found to occur in the potential regime between -0.3 and ?1.8 V (vs. Fc/Fc+), respectively, in the case of [Py1,4]TFSA. In situ STM investigations reveal an effect of the anion on the interfacial processes. In situ I/U tunnelling spectroscopy shows that the band gap of the electrodeposits is ~1.1 eV, indicating that semiconducting silicon has been electrodeposited. Potentiostatic electrolysis was performed to deposit Si from the employed electrolytes at room temperature and at 100 °C. The deposits were characterised using scanning electron microscopy and X-ray diffraction. Thin films of Si could be obtained from the employed ionic liquids and the quality of the deposits was significantly improved at 100 °C. 相似文献
387.
Some copper(I) complexes of the formula [Cu(L)(PPh3)2]X (1-4) [where L = 2-phenyl-3-(benzylamino)-1,2-dihydroquinazolin-4(3H)-one; PPh3 = triphenylphosphine; X = Cl−, NO3−, ClO4− and BF4−] have been prepared and characterized on the basis of elemental analysis, IR, UV-Vis and 1H NMR spectral studies. The representative complex of the series 4 has been characterized by single crystal X-ray diffraction which reveal that in the complex the central copper(I) ion assumes the irregular distorted-tetrahedral geometry. Cyclic voltammetry of the complexes indicate a quasireversible redox behavior corresponding to Cu(II)/Cu(I) couple. All the complexes exhibit intraligand (π → π∗) fluorescence with high quantum yield in dichloromethane solution. 相似文献
388.
Stops in Swiss German contrast only in quantity in all word positions; aspiration and voicing play no role. As in most languages with consonant quantity contrast, geminate stops are produced with significantly longer closure duration (CD) than singletons in an intersonorant context. This holds word medially as well as phrase medially, e.g., [oni tto:s] "without roar" versus [oni to:s] "without can." Since the stops are voiceless, no CD cue distinguishes geminates from singletons phrase initially. Nevertheless, do speakers utilize articulatory means to maintain the contrast? By using electropalatography, the articulatory and acoustic properties of word-initial alveolar stops were investigated in phrase-initial and phrase-medial contexts. The results are threefold. First, as expected, CD and contact duration of the articulators mirror each other within a phrase: Geminates are longer than singletons. Second, phrase initially, the contact data unequivocally establish a quantity distinction. This means that-even without acoustic CD cues for perception-geminates are articulated with substantially longer oral closure than singletons. Third, stops are longer in phrase-initial than phrase-medial position, indicating articulatory strengthening. Nevertheless, the difference between geminates and singletons phrase initially is proportionately less than in phrase-medial position. 相似文献
389.
De P Maji S Chowdhury AD Mobin SM Mondal TK Paretzki A Lahiri GK 《Dalton transactions (Cambridge, England : 2003)》2011,40(46):12527-12539
The present article describes ruthenium nitrosyl complexes with the {RuNO}(6) and {RuNO}(7) notations in the selective molecular frameworks of [Ru(II)([9]aneS(3))(bpy)(NO(+))](3+) (4(3+)), [Ru(II)([9]aneS(3))(pap) (NO(+))](3+) (8(3+)) and [Ru(II)([9]aneS(3))(bpy)(NO˙)](2+) (4(2+)), [Ru(II)([9]aneS(3))(pap)(NO˙)](2+) (8(2+)) ([9]aneS(3) = 1,4,7-trithiacyclononane, bpy = 2,2'-bipyridine, pap = 2-phenylazopyridine), respectively. The nitrosyl complexes have been synthesized by following a stepwise synthetic procedure: {Ru(II)-Cl} → {Ru(II)-CH(3)CN} → {Ru(II)-NO(2)} → {Ru(II)-NO(+)} → {Ru(II)-NO˙}. The single-crystal X-ray structure of 4(3+) and DFT optimised structures of 4(3+), 8(3+) and 4(2+), 8(2+) establish the localised linear and bent geometries for {Ru-NO(+)} and {Ru-NO˙} complexes, respectively. The crystal structures and (1)H/(13)C NMR suggest the [333] conformation of the coordinated macrocyclic ligand ([9]aneS(3)) in the complexes. The difference in π-accepting strength of the co-ligands, bpy in 4(3+) and pap in 8(3+) (bpy < pap) has been reflected in the ν(NO) frequencies of 1945 cm(-1) (DFT: 1943 cm(-1)) and 1964 cm(-1) (DFT: 1966 cm(-1)) and E°({Ru(II)-NO(+)}/{Ru(II)-NO˙}) of 0.49 and 0.67 V versus SCE, respectively. The ν(NO) frequency of the reduced {Ru-NO˙} state in 4(2+) or 8(2+) however decreases to 1632 cm(-1) (DFT: 1637 cm(-1)) or 1634 cm(-1) (DFT: 1632 cm(-1)), respectively, with the change of the linear {Ru(II)-NO(+)} geometry in 4(3+), 8(3+) to bent {Ru(II)-NO˙} geometry in 4(2+), 8(2+). The preferential stabilisation of the eclipsed conformation of the bent NO in 4(2+) and 8(2+) has been supported by the DFT calculations. The reduced {Ru(II)-NO˙} exhibits free-radical EPR with partial metal contribution revealing the resonance formulation of {Ru(II)-NO˙}(major)?{Ru(I)-NO(+)}(minor). The electronic transitions of the complexes have been assigned based on the TD-DFT calculations on their DFT optimised structures. The estimated second-order rate constant (k, M(-1) s(-1)) of the reaction of the nucleophile, OH(-) with the electrophilic {Ru(II)-NO(+)} for the bpy derivative (4(3+)) of 1.39 × 10(-1) is half of that determined for the pap derivative (8(3+)), 2.84 × 10(-1) in CH(3)CN at 298 K. The Ru-NO bond in 4(3+) or 8(3+) undergoes facile photolytic cleavage to form the corresponding solvent species {Ru(II)-CH(3)CN}, 2(2+) or 6(2+) with widely varying rate constant values, (k(NO), s(-1)) of 1.12 × 10(-1) (t(1/2) = 6.2 s) and 7.67 × 10(-3) (t(1/2) = 90.3 s), respectively. The photo-released NO can bind to the reduced myoglobin to yield the Mb-NO adduct. 相似文献
390.
A comprehensive review has been made to discuss the role of various radionuclides of lanthanide series elements in the field
of nuclear medicine. The role of several pharmaceuticals labeled with radiolanthanides and used for investigative purposes
like measurement of cerebral blood flow, bone density measurement, bone marrow imaging, etc., have been described. The role
of lanthanide radionuclides in radiation synovectomy, radioimmunotherapy, etc., have also been discussed. Methods of preparation
of some representative radiopharmaceuticals like153Sm-EDTMP,153Sm-HYP, have been presented. An outline on the production of carrier free radioisotopes of lanthanide series elements has
been given. 相似文献