Enhancing the Linear Dynamic Range in Multi-Channel Single Photon Detector beyond 7OD.

We present design, implementation, and characterization of a single photon detector based on 32-channel PMT sensor [model H7260-20, Hamamatsu]. The developed high speed electronics enables the photon counting with linear dynamic range (LDR) up to 10count/s per detector's channel. The experimental characterization and Monte-Carlo simulations showed that in the single photon counting mode the LDR of the PMT sensor is limited by (i) "photon" pulse width (current pulse) of 900ps and (ii) substantial decrease of amplitudes of current pulses for count rates exceeding 10 count/s.

Detection of multi-color fluorescent objects with single photon spectrometer.

Single photon counting is the most sensitive and accurate method for detection of very weak fluorescent signals obtained in many applications such as DNA sequencing, detection of biological reporters on micro-beads, detection of droplets in micro-fluidic systems, etc. In this paper we describe the use of single photon spectrometer for detection and characterization of very weak multicolor fluorescence produced by mixtures of various fluorescent dyes and quantum dots.

Ultra sensitive sensor with enhanced dynamic range for high speed detection of multi-color fluorescence radiation.

This paper describes design of the new ultra sensitive sensor system for fluorescence detection applications. System comprises two units: optical spectra separation unit and detection unit. Optical unit of the sensor performs spatial spectra separation of signal from the laser excited fluorescence, and resulting spectra is collected in the detection part of the system.

Electrokinetic injection of DNA from gel micropads: basis for coupling polony technology with CE separation.

We propose a novel method for electrokinetic injection of DNA samples into capillaries from nanoliter gel micropads, deposited on glass slides, which are coated with electroconducting film. Theoretical and experimental proof is presented for the proposed method. The method allows efficient and highly precise injection without physical contact between the gel pad and the capillary.

Experimental study of the formation of high-resistivity zones at the gel/buffer interface in CE.

A novel, nondamaging method for experimental characterization of the formation and propagation of high-resistivity zones in CE, based on the measurement of time-dependent Joule heating on the outer capillary surface is proposed. The method detects propagation of resistive regions in capillaries in real time and allows the estimation of their velocity and resistance. The presented experimental data are in agreement with the results of the computer simulation as well as with previous data on the subject.

Dynamic range of fluorescence detection and base-calling accuracy in DNA sequencer based on single-photon counting.

Recently, we developed a family of high-performance automated capillary DNA sequencing instruments based on a single-photon detection of fluorescently labeled DNA fragments. Our machines employ digital and broadband techniques, essential for achieving superior instrument sensitivity and dynamic range. In the present paper, we discuss limitations of the instrument's performance caused by the nonlinearity of single-photon detectors as well as methods for nonlinearity compensation which increase the detection dynamic range and base-calling accuracy.

Formation of a resistive region at the anode end in DNA capillary electrophoresis.

We have studied the formation of a resistive region in the capillary during DNA separation. This effect is caused by an unequal change in the mobilities of cations and anions at the interface between the running buffer solution and the capillary. We studied the motion of the resistive region boundary by sequential removal of portions of the affected capillary end.

[Improved schedules for steam sterilization of rubber medical products].

The effect of residual air concentration in a sterilization chamber and of technique of its removal on the heating rate of an object are studied as well as the effect of packaging density on the process of air removal and on the object's warming up. The following rubber medical products have been used as objects: surgical gloves, drainage and connecting tubes, and stoppers. The studies make it possible to define the gravity-fluctuation technique as the optimum one for air removal, and the optimum loading density of sterilization boxes that ensures the object sterility.

[Electric stimulation of intestinal motility in the postoperative period].

The authors performed 208 electric stimulations of the bowel motor activity with the aim of prophylaxis and treatment of its postoperative paresis. The studies have shown that electric stimulation accelerated considerably the process of rehabilitation of the bowel motor function, but it would not prevent the development of grave functional intestinal obstruction. But nevertheless electric stimulation is a highly effective method in the complex of measures for treatment of grave functional intestinal obstruction.