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31.
32.
Nano-crystalline hydroxyapatite (HA), Ca10(PO4)6(OH)2 has been synthesized by a precipitate conversion technique using hydroxide gel at lower temperatures, e.g. 80 °C. HA crystallizes in hexagonal structure (space group: P63/m) having lattice parameters: and and around 17 nm in crystallite-size for the 80 °C-heated sample. SEM micrographs show hexagonal crystallites of average particle dimensions approximately 50×20 nm for 80 °C heated sample. The structure analysis by XRD, FTIR, 1H and 31P MAS NMR show the existence of structural disorder at the particle surface that either does not form hydrogen bonding due to lack of adequate bonding parameters or forms a very weak dipolar bonding. The structural disorder has been explained as a result of chemical interactions between the phosphate groups either with the surface adsorbed water or the hydroxyl groups at the surface of the nano-particles. 相似文献
33.
JPC – Journal of Planar Chromatography – Modern TLC - A simple and precise high-performance thin-layer chromatographic (HPTLC) method has been established for simultaneous analysis of... 相似文献
34.
Anuja Datta Subhendu K. Panda Subhadra Chaudhuri 《Journal of solid state chemistry》2008,181(9):2332-2337
ZnS nanorods doped with 0-15 mol% of Cu have been prepared by simple solvothermal process. With gradual increase in the Cu concentration, phase transformation of the doped ZnS nanorods from wurtzite to cubic was observed. Twins and stacking faults were developed due to atomic rearrangement in the heavily doped ZnS nanorods during phase transformation. UV-vis-NIR absorbance spectroscopy ruled out the presence of any impure Cu-S phase. The doped ZnS nanorods showed luminescence over a wide range from UV to near IR with peaks at 370, 492-498, 565 and 730 nm. The UV region peak is due to the near-band-edge transition, whereas, the green peak can be related to emission from elementary sulfur species on the surfaces of the nanorods. The orange emission at 565 nm may be linked to the recombination of electrons at deep defect levels and the Cu(t2) states present near the valence band of ZnS. The near IR emission possibly originated from transitions due to deep-level defects. 相似文献
35.
The concepts of differentiability, convexity, generalized convexity and minimization of a fuzzy mapping are known in the literature. The purpose of this present paper is to extend and generalize these concepts to fuzzy mappings of several variables using Buckley–Feuring approach for fuzzy differentiation and derive Karush–Kuhn–Tucker condition for the constrained fuzzy minimization problem. 相似文献
36.
Amy F. Mielke Richard G. Seasholtz Kristie A. Elam Jayanta Panda 《Experiments in fluids》2005,39(2):441-454
Measurement of time-averaged velocity, density, temperature, and turbulence velocity fluctuations in sparsely seeded gas flows using a non-intrusive, point-wise technique based on Rayleigh and Mie scattering is discussed. A Fabry-Perot interferometer (FPI) is used to spectrally resolve laser light scattered by molecules and particulates in gas flows. The spectral content of the scattered light provides information about velocity, density, and temperature of the gas. A CCD camera is used to record images of the fringes formed by scattered light passing through the interferometer. Models of the spectral components are used in a least squares fitting routine to estimate the parameters from fringe images. Flow measurements are presented for subsonic and supersonic jet flows. The application range for this technique is mostly for high velocity situations (>25 m/s). Velocity, density, temperature, and turbulence velocity fluctuations were determined with accuracies within 5 m/s, 4%, 2%, and 5 m/s, respectively. 相似文献
37.
A rapid, sensitive and specific high‐performance thin‐layer chromatographic (HPTLC) method was developed and validated for determination of gliotoxin in Aspergillus infected immunocompromised patients with invasive aspergillosis (IA). Densitometric analysis of gliotoxin was carried out in the absorbance mode at 254 nm after single‐step extraction with chloroform. The method uses TLC aluminum plates pre‐coated with silica gel 60F‐254 as a stationary phase and toluene–isoamyl alcohol–methanol (10:0.5:0.5, v/v/v) as mobile phase, which gives compact spot of gliotoxin (Rf = 0.51). The calibration curve was linear (r2 ≥ 0.994) between peak area and concentration in the tested range of 100–1000 ng spot?1 with minimum detectable range 0.025 ng μ?1 of serum sample. The mean ± SD value of slope and intercept of the standard chromatogram of gliotoxin were found to be 523.2 ± 1.555635 and 915.8 ± 30.68843, respectively. The developed method is simple, rapid, precise and less costly than earlier diagnostic methods, and different serum samples can be run on a single TLC plate for comparative analysis. The proposed method can be used to analyze gliotoxin in patient serum for easy, rapid and cost‐effective diagnosis of IA. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
38.
Anup RanaPradeepta K. Panda 《Tetrahedron letters》2011,52(21):2697-2701
Vilsmeier-Haack formylation of 3,4-dimethoxypyrrole led to the unprecedented formation of 3-chloro-4-methoxypyrrole-2-aldehyde instead of the desired dialdehyde. Subsequent reduction and acid catalyzed cyclization led to the formation of type I, 3,8,13,18-tetrachloro-2,7,12,17-tetramethoxyporphyrin in approximately 6% yield. 相似文献
39.
A temperature-dependent integrated kinetics for the overall process of photosynthesis in green plants is discussed. The C4 plants are chosen and in these plants, the rate of photosynthesis does not depend on the partial pressure of O2. Using some basic concepts like chemical equilibrium or steady state approximation, a simplified scheme is developed for
both light and dark reactions. The light reaction rate per reaction center (R′
1) in thylakoid membrane is related to the rate of exciton transfer between chlorophyll neighbours and an expression is formulated
for the light reaction rate R′
1. A relation between R′
1 and the NADPH formation rate is established. The relation takes care of the survival probability of the membrane. The CO2 saturation probability in bundle sheath is also taken into consideration. The photochemical efficiency (ϕ) is expressed in terms of these probabilities. The rate of glucose production is given by R
glucose = (8/3)(R′
1
v
L
)ϕ(T)
g
(T) ([G3P]/[P
i]2
leaf)SS
Q
G3P→glucose where g is the activity quotient of the involved enzymes, and G3P represent glycealdehyde-3-phosphate in steady state. A Gaussian
distribution for temperature-dependence and a sigmoid function for de-activation are incorporated through the quotient g. In general, the probabilities are given by sigmoid curves. The corresponding parameters can be easily determined. The theoretically
determined temperature-dependence of photochemical efficiency and glucose production rate agree well with the experimental
ones, thereby validating the formalism. 相似文献
40.
In this paper we report a new method of fabrication of surface tensionconfined microfluidic devices on glass. We have also
successfully carried out some well-known chemical reactions in these fluidic channels to demonstrate the usefulness of these
wall-less microchannels. The confined flow path of liquid was achieved on the basis of extreme differences in hydrophobic
and hydrophilic characters of the surface. The flow paths were fabricated by making parallel lines using permanent marker
pen ink or other polymer on glass surfaces. Two mirror image patterned glass plates were then sandwiched one on top of the
other, separated by a thin gap-created using a spacer. The aqueous liquid moves between the surfaces by capillary forces,
confined to the hydrophilic areas without wetting the hydrophobic lines, achieving liquid confinement without physical side-walls.
We have shown that the microfluidic devices designed in such a way can be very useful due to their simplicity and low fabrication
cost. More importantly, we have also demonstrated that the minimum requirement of such a working device is a hydrophilic line
surrounded by hydrophobic environment, two walls of which are constituted of air and the rest is made of a hydrophobic surface. 相似文献