排序方式: 共有39条查询结果,搜索用时 15 毫秒
21.
T.N. Adam S. Bedell A. Reznicek D.K. Sadana A. Venkateshan T. Tsunoda T. Seino J. Nakatsuru S.R. Shinde 《Journal of Crystal Growth》2010,312(23):3473-3478
Epitaxial (1 0 0) silicon layers were grown at temperatures ranging from 500 to 800 °C in a commercial cold-wall type UHV/CVD reactor at pressures less than 7×10−5 Torr. The substrates were 300 mm SIMOX SOI wafers and spectroscopic ellipsometry was used to assess growth rates and deposition uniformities. High-resolution atomic force microscopy (AFM) was employed to verify the atomic terrace configuration that resulted from epitaxial step-flow growth. Deposition from disilane exhibited a nearly perfect reaction limit for low temperatures and high precursor flow rates (partial pressures) with measured activation energies of ≈2.0 eV, while a linear dependence of growth rate on precursor gas flow was found for the massflow-controlled regime. A similar behavior was observed in the case of silane with substantially reduced deposition rates in the massflow-limited regime and nearly a factor of 2 reduced growth rates deep in the reaction limited regime. High growth rates of up to 50 μm/h and non-uniformities as low as 1σ=1.45% were obtained in the massflow-limited deposition regime. Silicon layers as thin as 0.6 nm (4.5 atomic layers ) were deposited continuously as determined using a unique wet chemical etching technique as well as cross-sectional high-resolution transmission electron microscopy (HRTEM). In contrast, epitaxial silicon deposited in RPCVD at 10 Torr using disilane within the same temperature range showed imperfect reaction limitation. While activation energies similar to that of UHV/CVD were found, no partial pressure limitation could be observed. Furthermore, layers deposited using disilane in RPCVD exhibited a large number of defects that appeared to form randomly during growth. We attribute this effect to gas phase reactions that create precursor fragments and radicals—an effect that is negligible in UHV/CVD. 相似文献
22.
Satheeshmanikandan RS Thappali Kanthikiran VS Varanasi Sridhar Veeraraghavan Swaroop Kumar VS Vakkalanka Mukkanti K 《Journal of mass spectrometry : JMS》2012,47(12):1612-1619
A sensitive and reliable high‐performance liquid chromatography–mass spectrometry (LC–MS/MS) was developed and validated for simultaneous quantification IC87114, roflumilast (RFM), and its active metabolite roflumilast N‐oxide (RFN) using tolbutamide as an internal standard. The analytes were extracted by using liquid–liquid extraction and separated on a reverse phase C18 column (50 mm × 3 mm i.d., 4.6 µ) using methanol: 2 mM ammonium acetate buffer, pH 4.0 as mobile phase at a flow rate 1 mL/min in gradient mode. Selective reaction monitoring was performed using the transitions m/z 398.3 > 145.9, 403.1 >186.9, 419.1 > 187.0 and 271.1 > 155.0 to quantify quantification IC87114, RFM, RFN and tolbutamide, respectively. The method was validated over the concentration range of 0.1–60 ng.mL?1 for RFM and RFN and 6 to 2980 ng.mL?1 for IC87114. Intra‐ and inter‐day accuracy and precision of validated method were within the acceptable limits of <15% at all concentrations. Coefficients of correlation (r2) for the calibration curves were >0.99 for all analytes. The quantitation method was successfully applied for simultaneous estimation of IC87114, RFM and RFN in a pharmacokinetic drug–drug interaction study in Wistar rats. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
23.
Munshi G Mustafa Sudhir Raniwala T Awes B Rai RS Bhalerao JG Contreras RV Gavai SK Ghosh P Jaikumar GC Mishra AP Mishra H Mishra B Mohanty J Nayak J-Y Ollitrault SC Phatak L Ramello R Ray PK Sahu AM Srivastava DK Srivastava VK Tiwari 《Pramana》2006,67(5):961-981
This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and
work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported. 相似文献
24.
Profile of selenium in soil and crops in seleniferous area of Punjab,India by neutron activation analysis 总被引:1,自引:0,他引:1
N. Sharma R. Prakash A. Srivastava U. S. Sadana R. Acharya N. T. Prakash A. V. R. Reddy 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(1):59-62
In the Nawanshahr–Hoshiarpur region of Punjab, India, more than 1000 hectares of agricultural land is significantly affected
by high levels of selenium (Se). Studies were carried out to examine Se levels in soil and crops such as wheat grains, wheat
husk, rice, maize and mustard using neutron activation analysis. The Se concentrations in soil and crop products were found
to be ranging from 2.7 to 6.5 mg kg−1 and 13 to 670 mg kg−1, respectively, indicating significantly high selenium in these crop products. Two reference materials were analysed for Se
contents by INAA as controls. 相似文献
25.
26.
27.
28.
Sadana AK Liang F Brinson B Arepalli S Farhat S Hauge RH Smalley RE Billups WE 《The journal of physical chemistry. B》2005,109(10):4416-4418
Large fullerenes and carbon-coated metal nanoparticles that are formed during the synthesis of carbon nanotubes have been functionalized by the addition of alkyl radicals and isolated by extraction into chloroform. The soluble, functionalized fullerenes have been isolated from raw single-wall carbon nanotube (SWNT) material prepared by laser oven, direct current arc, and high-pressure carbon monoxide production methods. Analyses of the extracted large fullerenes were carried out by thermogravimetric analysis, UV-vis-near-IR, laser desorption ionization mass spectrometry, and high-resolution transmission electron microscopy. 相似文献
29.
30.
A fractal analysis is made for antigen-antibody binding kinetics for different biosensor applications available in the literature.
Both types of examples are considered wherein: (1) the antigen is in solution and the antibody is immobilized on the fiberoptic
surface, and (2) the antibody is in solution and the antigen is immobilized on the fiberoptic surface. For example, when the
antibody is immobilized on the surface, an increase in the antigenClostridium botulinum toxin A concentration in solution leads to (1) a decrease in the fractal dimension value or state of disorder, and (2) a
higher rate constant for binding on the fiberoptic surface. An analysis of the effect of the influence of different parameters
on the fractal dimension values for a particular example, such as varying treatments or incubation procedures, helps provide
insights into the conformational states and reactions occurring on the fiberoptic surface. The analysis of the different examples
taken together provides novel physical insights into the state of “disorder” and reactions occurring on the surface. Such
types of analysis should help contribute toward manipulating the reactions occurring on the fiberoptic surfaces in desired
directions. 相似文献