排序方式: 共有86条查询结果,搜索用时 265 毫秒
51.
The stoichiometry range and lithium ion conductivity of Li5+x
Ba
x
La3−x
Ta2O12 (x = 0, 0.25, 0.50, 1.00, 1.25, 1.50, 1.75, 2.00) with garnet-like structure were studied. The powder X-ray diffraction data
of Li5+x
Ba
x
La3−x
Ta2O12 indicated that single phase oxides with garnet-like structure exist over the compositional range 0 ≤ x ≤ 1.25; while for x = 1.5, 1.75 and 2.00, the presence of second phase in addition to the major garnet like phase was observed. The cubic lattice
parameter increases with increasing x and reaches a maximum at x = 1.25 then decreases slightly with further increase in x in Li5+x
Ba
x
La3−x
Ta2O12. The impedance plots of Li5+x
Ba
x
La3−x
Ta2O12 samples obtained at 33 °C indicated a minimum grain-boundary resistance (R
gb) contribution to the total resistance (R
b + R
gb) at x = 1.0. The total (bulk + grain boundary) ionic conductivity increases with increasing lithium and barium content and reaches
a maximum at x = 1.25 and then decreases with further increase in x in Li5+x
Ba
x
La3−x
Ta2O12. Scanning electron microscope investigations revealed that Li6.25Ba1.25La1.75Ta2O12 is much more dense, and the grains are more regular in shape. Among the investigated compounds, Li6.25Ba1.25La1.75Ta2O12 exhibits the highest total (bulk + grain boundary) and bulk ionic conductivity of 5.0 × 10−5 and 7.4 × 10−5 S/cm at 33 °C, respectively. 相似文献
52.
Quinoxaline-imidazolium receptors for unique sensing of pyrophosphate and acetate by charge transfer
Singh NJ Jun EJ Chellappan K Thangadurai D Chandran RP Hwang IC Yoon J Kim KS 《Organic letters》2007,9(3):485-488
[structure: see text] Quinoxaline derivatives (1-4) bearing two imidazolium moieties are found to strongly bind anions and show unique charge-transfer fluorescent responses to pyrophosphate and acetate, whereas they show excimer formation with other anions. Anion-binding studies are investigated with fluorescence and 1H NMR analysis, single-crystal X-ray analysis, and theoretical calculations. 相似文献
53.
Bandaru VV Bandaru SR Somalanka SR Mendu DR Imandi SB Bejawada SR Medicherla NR Devarajan T Karothi J Chityala A 《Applied biochemistry and biotechnology》2007,143(3):224-235
Application of statistical experimental designs for optimization of fermentation parameters to enhance ethanol production,
which is an economical and renewable energy source using Saccharomyces cerevisiae NCIM 3090 from palmyra jaggery, was studied in a batch fermentor. Using Plackett–Burman design, impeller speed, concentrations
of CoCl2 and KH2PO4 were identified as significant variables, which highly influenced ethanol production, and these variables were further optimized
using a central composite design (CCD). The ethanol production was adequately approximated with a full quadratic equation
obtained from three factors and five levels of CCD. Maximum ethanol concentration of 132.56 g/l (16.8% [v/v]) was obtained
for an impeller speed of 247.179 (≈250) rev/min, CoCl2 of 0.263 g/l and KH2PO4 of 2.39 g/l. A second-order polynomial regression model was fitted and was found adequate with R
2 of 0.8952. This combined statistical approach enables rapid identification and investigation of significant parameters for
improving the ethanol production and could be very useful in optimizing processes. 相似文献
54.
Joby E. Joy Eric Atamanik Rohini Mani Abanti Nag R.M. Tiwari V. Thangadurai J. Gopalakrishnan 《Solid State Sciences》2010,12(12):1970-1976
We describe the synthesis, structures and dielectric properties of new perovskite oxides of the formula, Ba3MIIITiMVO9, for MIII = Fe, Ga, Y, Lu and MV = Nb, Ta, Sb. While MV = Nb and Ta oxides adopt disordered/partially ordered 3C perovskite structures where MIII/Ti/MV metal-oxygen octahedra are corner-connected, the MV = Sb oxides show a distinct preference for the 6H structure, where SbV/TiIV metal-oxygen octahedra share a common face forming (Sb,Ti)O9 dimers that are corner-connected to the MIIIO6 octahedra. The preference of antimony oxides (SbV:4d10) for the 6H structure – which arises from a special SbV–O chemical bonding that tends to avoid linear Sb–O–Sb linkages unlike NbV/TaV:d0 atoms which prefer ~180° Nb/Ta–O–Nb/Ta linkages – is consistent with the crystal chemistry of MV–O oxides in general. The dielectric properties reveal a significant difference among MIII members. All the oxides with the 3C structure excepting those with MIII = Fe show a normal low loss dielectric behaviour with ε = 20–60 in the temperature range 50–400 °C; the MIII = Fe members with this structure (MV = Nb, Ta) display a relaxor-like ferroelectric behaviour with large ε values at frequencies ≤1 MHz (50–500 °C). 相似文献
55.
Surinderjit Singh BhellaVenkataraman Thangadurai 《Solid State Ionics》2011,192(1):229-234
In this paper, we report the synthesis, crystal structure and electrical transport properties of new K-doped Ba3CaNb2O9 (BCN) and investigate their chemical stability in H2O and pure CO2 at elevated temperature. The powder X-ray diffraction (PXRD) of Ba2.5K0.5CaNb2O9 − δ, Ba2.25K0.75CaNb2O9 − δ, Ba2KCaNb2O9 − δ, and Ba1.75K1.25CaNb2O9 − δ showed the formation of a single-phase double perovskite (A3BB/2O9)-like cell with a lattice constant of a ∼ 2ap (where ap is a simple perovskite cell of ∼ 4 Å). Perovskite-like structure was found to be retained after treating with CO2 at 700 °C and also after boiling H2O for 120 h. The lattice constant of CO2 and H2O treated samples was found to be comparable to that of the corresponding as-prepared compound. The total electrical conductivity of all the investigated K-doped BCN increases with increasing K content in BCN in various atmospheres, including air, dry H2, wet N2 and wet H2. The electrical conductivity in dry and wet H2 atmospheres was found to be higher than that of air in the temperature range of 300-700 °C, while in wet N2 a slightly lower value was observed. Among the compounds investigated in the present study Ba1.75K1.25CaNb2O9 − δ showed the highest total electrical conductivity of 1 × 10− 3 S/cm in dry H2 at 700 °C with an activation energy of 1.28 eV in the temperature range of 300-700 °C. 相似文献
56.
Mass-balanced (1)H/(2)H-isotope dipeptide tag (MBIT) is diversified as aliphatic tags for multiplexed protein quantification. Aliphatic MBITs are based on the N-acetyl-Xxx-Ala dipeptide, where Xxx is an artificial amino acid with a linear alkyl side chain from C(2)H(5) to C(8)H(17) (C(2)-C(8) tags). (1)H/(2)H isotopes are encoded in the methyl groups of N-acetyl and Ala to yield a pair of isobaric tags with 2-plex quantitation signals separated by 3 Da. C(2)-C(5) tags are prepared by solid-phase synthesis, while C(6)-C(8) tags are synthesized by olefin metathesis in solution. These aliphatic tags are made reactive toward the primary amines of peptides, and the relative abundances of quantitation signals are characterized using both matrix-assisted laser desorption ionization and electrospray ionization tandem mass spectrometry. MBIT-linked peptides co-migrate in reverse-phase liquid chromatography (LC), and their tandem mass spectra exhibit 2-plex quantitation signals as well as sequence ions in similar abundances. As the length of alkyl side chain increases, C(2)-C(8) tags show a stepwise increase in both the LC retention time and the relative abundance of quantitation signals. In addition, the quantitation linearity is well-maintained in a 15-250 fmol range. The multiplexing capability of aliphatic MBITs is demonstrated by applying three different tags (C(6)-C(8) tags) to the quantification of yeast heat shock proteins expressed under four different physiological conditions. 相似文献
57.
All-solid-state thin film batteries are feasible by employing Al as anode and LiPON as electrolyte which are subsequently
deposited by sputtering. The lithium ion conductivity of ∼ 10−6 S/cm for the thin film LiPON is in agreement with data reported for bulk material. The high voltage cathode Li2CoMn3O8 could be prepared by forming the compound by the combustion method andsubsequent e-beam evaporation of this material with
the addition of 20 wt.-% LiNO3 at an oxygen partial pressure of 10−5 mbar. The thin film cells could be operated between 3 and 5 V vs. Al, LiAl. The chemical diffusion coefficient was found
to be in the range from 10−13 to 10−12 cm2/s at room temperature by employing the GIT-technique for the composition x of Li2-xCoMn3O8 in the range from 0.1 to 1.6. Impedance studies of the complete battery system revealed a charge transfer resistance of 290
Θ, a double layer capacity of ∼ 45–70 μF for an electrode area of 6.7 cm2 and a rate determining chemical diffusion coefficient in the range from 10−12 to 10−11 cm2/s.
Paper presented at the 9th EuroConference on Ionics, Ixia, Rhodes, Greece, Sept. 15–21, 2002. 相似文献
58.
S Thangadurai J T Abraham A K Srivastava M Nataraja Moorthy S K Shukla Y Anjaneyulu 《Analytical sciences》2005,21(7):833-838
X-ray powder diffraction (XRD) data for eight beta-lactam viz., ampicillin sodium, ampicillin trihydrate, penicillin G procaine, benzathine penicillin, benzyl penicillin sodium, cefalexin, cefotaxime sodium and ceftriaxone sodium; three tetracyclines viz., doxycycline hydrochloride, oxytetracycline dihydrate and tetracycline hydrochloride; and two macrolide viz., azithromycin and erythromycin estolate antibiotic drugs were obtained using a powder diffractometer. The drugs were scanned from Bragg angles (2theta) of 10 degrees to 70 degrees. The obtained data were tabulated in terms of the lattice spacing (A) and relative line intensities (I/I(I)). This new information may be useful for identifying these drugs from confiscated materials, which has been frequently encountered in forensic laboratories. 相似文献
59.
60.