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61.
A new ultrasonic method — thermoacoustic analysis — is reported for the detection of the added chemical preservatives in branded
milk. The nature of variation and shift in the thermal response of the acoustic parameters specific acoustic impedance, adiabatic
compressibility and Rao’s specific sound velocity for different samples of branded milk as compared to the chemical added
pure milk are explained as due to the presence of chemicals in these branded samples. 相似文献
62.
T. C. Lilly 《Applied physics. B, Lasers and optics》2011,104(4):961-968
The continuing advance of laser technology enables a range of broadly applicable, laser-based flow manipulation techniques
relevant to a number of aerospace, basic physics, and microtechnology applications. Theories for laser-molecule interactions
have been under development since the advent of laser technology. Yet, the theories have not been adequately integrated into
kinetic flow solvers. Realizing this integration would greatly enhance the scaling of laser-species interactions beyond the
realm of ultra-cold atomic physics. This goal was realized in the present study. A representative numerical investigation
of laser-based neutral nonpolar molecular flow manipulations was conducted using non-resonant pulsed laser fields. The numerical
tool employed for this study was a specifically modified version of the Direct Simulation Monte Carlo statistical kinetic
solver known as SMILE. Flow steering and collimation was simulated for a nitrogen effluence with a stagnation condition of
1 Pa and 300 K emptying into vacuum. The laser pulses were 250 mJ, 5 ns pulses at a wavelength of 532 nm. Flow modification
mapped out contours which followed the intensity gradient of the laser field, consistent with the use of the induced dipole
gradient force along the field’s radial direction and previously published experiments. 相似文献
63.
A non-aqueous solid phase extraction (SPE) method utilizing silica based strong cation exchange (SCX) was developed and optimized for the enrichment of alkaloids. In this method, silica based SCX SPE columns were used for the elimination of non-alkaloid compounds and the preconcentration of alkaloids from the extracts. Mass spectrometry was employed to analyze the alkaloid-enriched fraction, and results showed that the SPE method developed in this study was effective for the removal of non-alkaloids. Then, this pretreatment method was combined with high performance liquid chromatography for the quantification of scopolamine and hyoscyamine from Scopolia tangutica Maxim. The recoveries of scopolamine and (-)-hyoscyamine were 98.51% and 91.12%, respectively. Relative standard deviation values were 1.4% for scopolamine and 1.6% for (-)-hyoscyamine. The linearity was good in the 0.01-0.8 mg mL(-1) range for hyoscyamine and 0.01-0.4 mg mL(-1) range for scopolamine. 相似文献