CHARACTERISTICS OF A GRIDLESS TWO-DIAPHRAGM ION GATE AT ATMOSPHERIC PRESSURE

As an ion gate for the formation of a short ion pulse in an ion mobility spectrometer, a gridless design with two coaxial diaphragms is proposed. It has been experimentally shown that, depending on the geometric and electrical parameters of this shutter, there is an optimal duration of the electric pulse opening the gate, which provide the maximum amplitude of the ion pulse.

RECENT TRENDS IN THE DEVELOPMENT OF SENSORS FOR PRE-EXPLOSIVE CONCENTRATIONS OF FLAMMABLE GASES AND VAPORS OF FLAMMABLE LIQUIDS (REVIEW)

This paper presents a review of current trends in the development of manufacturing technologies of sensors of pre-explosive concentrations of flammable gases and vapors of flammable liquids. Various types of gas sensors are discussed, including catalytic, semiconductor, and optical sensor types, and the principles of their operation. The advantages and disadvantages of each type of gas sensor are highlighted. New and traditional technologies for manufacturing sensitive elements that improve sensor parameters such as processability, miniaturization and reduce energy consumption are discussed. In conclusion, this article suggests future trends and prospects for development and research to improve the sensitivity and selectivity of sensors.

WIRELESS METHANE DETECTOR WITH TEMPERATURE MODULATED HEATING PROFILE

The results of development of an autonomous methane detector in a dynamic measurement mode are presented. Industrial catalytic sensor was used as a sensitive element. To prevent burnout of the catalytic sensor microheater which often occurs during pulsed heating, the special form of heating pulse has been developed. The proposed dynamic mode of the sensor heating provides the measurements with low power consumption and the required level of safety in the measurement range of pre-explosive methane concentrations from 0.1 to 2 vol.%. Based on the analysis of the obtained results, the estimation of autonomous operating time of the detector is given.

MEASUREMENT OF PARAMETERS OF BROADBAND EMISSION USING MINI-SPECTROMETERS

On the basis of mini-spectrometers, a reference lamp of the SIRSH type with a known color temperature, and line spectrum sources, an inexpensive hardware complex has been created for measuring the emission parameters of heterodiodes and interference filters. Examples of recording the emission of heterodiodes (full width at half maximum is 17–30 nm) with a maximum of emission in the region of 659 and 764 nm and measurement of an interference filter (FWHM of the bandwidth is 12 nm) with a maximum transmission of 727 nm are given. The emission parameters of the SIRSH standard lamp are introduced into the program for measuring and processing data, due to which it is possible to significantly refine the value of the wavelength of the maximum emission and transmission.

MASS SPECTROMETRIC STUDIES OF THE COMPOSITION OF VOLATILE ORGANIC COMPOUNDS RELEASED BY VARIOUS FUNGAL SPECIES OF GENUS LECANICILLIUM

For the first time, the quantitative and qualitative composition of volatile organic compounds (VOCs), released by strains of various species of entomopathogenic fungi (EF) of the genus Lecanicillium, was studied using a quadrupole mass spectrometer. Lecanicillium fungi are used as an alternative to chemical pesticides for plant protection. The main detected components of the gas phase over the EF mycelium on the 10th day of growing on the agar Czapek's medium were carbon dioxide (5–20%), oxygen (0.1–15%), acetone (0.2–12 ppm), pentane (up to 0.5 ppm), acetic acid (up to 0.15 ppm). Acetone and pentane were found in the VOCs of all studied strains, acetic acid — in 5 strains belonging to different species, in other strains it appeared after a longer period of time, or was absent completely. Among the VOCs of some strains, substances such as hexyl acetate, sulfur dioxide were found in small quantities. These substances may be responsible for the pathogenic and repellent properties of the studied fungi with respect to phytophages.

STUDY OF DE-ICING LIQUID WITH AN OPTOELECTRONIC REFRACTOMETER

This work highlights the development of optoelectronic refractometer to study anti-icing liquids. Determining the composition authenticity and the flow rate of these liquids has always been a relevant task for the airport maintenance units, engaged in the processing of the aircraft body. The paper presents the objects of research: aqueous solutions of ethylene glycol and propylene glycol, which make up 95% of the composition of liquids of TYPE I, TYPE II, TYPE IV. The structural diagram and appearance of an optoelectronic refractometer are given. The results of measurements of the temperature dependences of the refractive index n(t) for solutions of ethylene glycol and propylene glycol in the temperature range from 12 °C to 100 °C and for concentrations from 0% to 100% are obtained. The spectra of ultraviolet optical transmission in ethylene glycol and propylene glycol of high purity in the wavelength range λ 210–320 nm with an error not worse than T = 0.5% are studied. The technical characteristics of an optoelectronic refractometer are given.

ESTIMATION OF SPACE CHARGE INFLUENCE ON RESOLUTION OF ION-MOBILITY SPECTROMETER

The paper presents an analytical model describing the dynamics of ion cloud, taking into account the action of space charge during a motion in ion mobility spectrometer — starting from the reaction region, where the shutter forms an ion pulse, and the further drift of the formed ion pulse towards the collector. The presented model lets to estimate the degree of influence of the space charge on possible ion losses and the resolution of ion mobility spectrometer. The effect of the space charge becomes noticeable, starting with the ion density of 106 cm–3. Comparison of the results obtained using the analytical model with the results of numerical solution of the initial equations shows that they practically coincide.

ANALYSIS OF PRECISION PROBLEMS OF PRECISION INDUSTRIAL ROBOTS

The article highlights the issues of compliance of the mechanics of manipulators of precision industrial robots (PIRs) with the highest accuracy standards specified in the normative technical documentation and practically achieved in the fields of machine-building, instrument-making and electronic industries. In the spotlight there are the possibilities of systems of multi - connected control of complex spatial mechanisms with excessive degrees of freedom (including manipulators of PIRs), the possibilities of systems of multi-circuit control of PIR drives with precision sensors of linear and angular displacements, velocities, accelerations, acceleration gradients (in the future), the issues of matching these parameters with the parameters of the computational part of control systems — the bit depth of digital sensors (more than 20 digits) with an resolution of less than an arc second. PIR manipulators are used in systems of multi-connected and multi-circuit regulation and control with elements of artificial intelligence, such as automatic adjustment systems (AASs), automatic control systems (ACSs) and artificial intelligence systems (AISs). These problems are considered in a wide range, including the transition to the fields of nanotechnologies, specifically: for linear (nanometers) and angular (hundredths of arc seconds) measurements, as well as the measurements of velocities, accelerations, and acceleration gradients (in the future — for systems with a human operator in the loop, i.e. human-machine systems (HMSs)).

EXAMINATION OF DISINFECTANTS USING AN AUTOMATED SPECTROMETER OPERATING IN THE VISIBLE RANGE OF THE SPECTRUM

The paper highlights a modern spectral device for measuring the optical parameters of solid-state materials in liquid-phase. The development of these devices is promising for optical instrumentation and science in general, since these devices are informative, highly accurate and provide reliable information. In the paper the appearance, block diagram and lighting system of the spectrometer are presented. The spectral dependences of the transmission on the wavelength in the visible range of the spectrum for disinfectants Like, Grand, Aqualite (1% solutions) are obtained. For the analysis of the studied substances, specialized cuvettes with a working length from 0.1 to 0.5 mm and leucosapfir optical pads were used. The cuvettes were 0.05 mm thick. The spectrometer provided measurement of the transmission of disinfectants in the wavelength range of 380–760 nm with an error not worse than ΔТ ≤ 2%.

THE FIRST YEAR OF COVID-19 PANDEMY AND ANALYTICAL INSTRUMENTATION (short message)

We report on analytical instruments used by authors of Nature for study of COVID-19. For study of RNA massive parallel sequence is necessary, and for investigation of RNA-polymerase shotgun mass-spectrometry is used.