Publications by authors named "V T Krishnamachari"
Thermophysical properties of (single phase) binary CO2-alcohol mixtures under high pressure and moderate temperature conditions are important in supercritical fluid processes. An apparatus to measure mixture density as a function of temperature (up to 80 °C) and pressure (up to 15.9 MPa) over the full range of CO2 mass fractions was designed and commissioned.
View Article and Find Full Text PDFA framework is developed that combines electric field Monte Carlo simulations of random scattering with an angular-spectrum representation of diffraction theory to determine the amplitude and phase characteristics of tightly focused laser beams in turbid media. For planar sample geometries, the scattering-induced coherence loss of wave vectors at larger angles is shown to be the primary mechanism for broadening the focal volume. This approach for evaluating the formation of the focal volume in turbid media is of direct relevance to the imaging properties of nonlinear coherent microscopy, which rely on both the amplitude and phase of the focused fields.
View Article and Find Full Text PDFCoherent anti-Stokes Raman scattering (CARS) interferometry is used to deplete the anti-Stokes radiation emerging from a tightly focused spot. Near-to-complete depletion of the anti-Stokes radiation is obtained when a phase-controlled local oscillator field at the anti-Stokes frequency is out of phase with the induced CARS field in the focal volume. Unlike in traditional interferometry, this depleted energy is not spatially redistributed.
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- Certain beneficial bacteria known as PGPR can promote plant growth without direct contact, primarily through the release of volatile organic compounds (VOCs), though the exact mechanisms remain largely unclear.
- By analyzing the gene expression in Arabidopsis seedlings exposed to Bacillus subtilis strain GB03, researchers identified around 600 genes that were differentially expressed, impacting various plant functions including hormone regulation and stress response.
- The study found that VOCs from GB03 increase auxin production in the upper parts of the plant while decreasing it in the leaves and enhancing it in the roots, suggesting that these bacteria help regulate auxin transport, which is crucial for plant growth and cell expansion.
Focus-engineered coherent anti-Stokes Raman scattering microscopy: a numerical investigation.
J Opt Soc Am A Opt Image Sci Vis
April 2007
The coherent anti-Stokes Raman scattering (CARS) signal is calculated as a function of focal-field distributions with engineered phase jumps. We show that the focal fields in CARS microscopy can be shaped such that the signal from the bulk is suppressed in the forward detection mode. We present the field distributions that display enhanced sensitivity to vibrationally resonant object interfaces in the lateral dimension.
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