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Fluorescent nanocrystals composed of
semiconductor materials were first introduced for biological applications in the
late 1990s. The focus of this review is to give a brief survey of biological applications
of quantum dots (QDs) at the single QD sensitivity
level. These are described as follows: 1) QD blinking and bleaching statistics, 2) the use of
QDs in high speed single
particle tracking with a special focus on how to design the biofunctional coatings
of QDs which enable specific targeting to single proteins or lipids of interest, 3) a hybrid lipid-DNA analogue binding
QDs which allows for tracking single lipids in lipid bilayers, 4) two-photon fluorescence correlation spectroscopy
of QDs and 5) optical trapping and excitation of single QDs. In all of these applications, the focus is on the single particle
sensitivity level of QDs. The high applicability of QDs in live cell imaging experiments
held together with the prospects in localization microscopy and single molecule
manipulation experiments gave QDs a promising future in single molecule research.
is devoted to building-up of ultrahigh resolution cw-dye laser spectrometer
system. This system used self-frequency-stabilized and temperature-compensated
plano-confocal reference cavity. The one-way propagation is achieved using new
construction of optical diode. The laser frequency selection and tuning is
accomplished using Mach-Zehnder interferometer of free spectral range 42.5 GHz.
In combination with computerized tunable radio frequency technique, this system
is capable of a resolution of about ±1 KHz. Applications for measuring
high lying, weakly occupied metastable states of free atoms (line
548.792 nm of V-51) are investigated to a high degree of accuracy. The results
of the constants A and B of the hfs as measured by fluorescence spectroscopy
show that A = 160.762 and B = -17.918, while the
obtained results for the hfs constants A and B as measured by laser-RF double
resonance technique give A = 160.9950 and B = -17.3358.
The gas analyzer based on optical parametric oscillators
(OPO) and laser photo - acoustic spectroscopy is demonstrated. The optical
parametric oscillators based on fun – out PPLN and bulk crystal AgGaS2 with a two-pass pumping are developed. Wide tunable OPO is pumped by compact
nanosecond Nd: YLF laser. Pulse duration is 5 - 7 ns,
maximum pulse energy is 1.5 mJ at a frequency of 100-2000 Hz. OPO lasing
threshold is 10 - 16 mJ/cm2 at the spectral range 2.2 - 4 μm
for fun – out PPLN OPO and 12 - 20 mJ/cm2 at the spectral range 4 - 7.5 μm for
AgGaS2 OPO. Absorption
spectra of gaseous mixtures (CH4, C3H8,
C2H6, C2H4 and CO2) and
human’s breath were studied.
Possible early diagnostic application of optical methods (dielectrophoresis, spectral and imaging ellipsometry, Fourier-transform infrared spectroscopy, Raman spectroscopy) in studies of red blood cells and serum of patients with diffuse liver disease with varying degrees of fibrosis has been evaluated. Application of combined optical methods was confirmed to significantly improve the performance of sensitivity, specificity, and accuracy index as well as to achieve the reliable results in diagnosis of both severe fibrosis and slight ulterior liver fibrosis. Identified diagnostic potential of optical methods can be effectively utilized in noninvasive screening evaluation of stages of diffuse liver disease of various geneses.