RU2326737C9 - Method of focusing particles (alternatives) - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: application: for separation of particles, for concentration of particles in certain areas, for purification of substances. With the purpose of separation and concentration particles are focused (concentrated in certain areas inside sample or volume, where they are located; term "focusing" is used in the same sense that in case of isoelectric focusing or chromatofocusing). For this purpose particles are displaced in different directions with the help of alternating field (for instance, electric field or field of movable phase flow in chromatography) and, synchronously with alternating field particles or medium parameters that determine particles velocity, for instance, change their mobility, are modified. In one version these properties are modified by means of additional alternating effect (for instance, temperature changes). Medium or additional effect should be heterogeneous. In another version particles are displaced with the help of alternating field through series of cells, in which materials are located, through which the particles pass. In case of movement in different directions particles are passed through different materials.

EFFECT: creation of common method for focusing of particles in dissipative medium.

5 cl, 7 dwg

Description

The invention relates to the field of separation of substances, to the field of purification of substances and to the field of concentration of particles.

Many methods are known for separating particles in a dissipative medium using a field that moves them: using an electric field (see Stepanov A.V., Korchemnaya E.K. Electromigration method in inorganic analysis. - M .: Chemistry, 1979), when using the mobile phase drag field (see Analytical chromatography / K.I. Sakodynsky, V.V. Brazhnikov, S.A. Volkov and others - M .: Chemistry, 1993), using the vibration field (see I. Blekhman I. Vibration Mechanics. - M.: Fizmatlit, 1994. - Part 3).

Known methods for separating particles using an alternating asymmetric electric field. These methods are used in electrophoresis to separate large molecules that move in a constant field at the same speed. Under the influence of an electric field, the separated molecules or molecules of the medium are oriented. In an alternating field, different molecules reorient at different speeds and therefore different molecules move at different speeds (see Methods in Molecular Biology, vol. 12: Pulsed-Field Gel Electrophoresis. / Ed. By M. Burmeister, L. Ulanovsky. Humana Press , Totowa, New Jersey, 1992). In this method, particles are not focused. A known method of separation in two synchronous variable fields "Wilhelm RH, Rice AW, Roike RW, Sweed NH Parametric pumping - a dynamic principle for separating fluid mixtures // Ind. Eng. Chem. Fundamentals. - 1968. - v.7 - 337- 349 "and" Tverdislov VA, Yakovenko LV, Salov DV, Tverdislova IL, Hianik T. The Parametric Pump Mechanism in Separation of Components in Heterogeneous Systems. I. Macroscopic Distributed Systems // Gen. Physiol. Biophys. - 1999. - v. 18, 73-85. " In this method, there are two alternating synchronous fields, one moving the particles, and the other changing the distribution of particles between the two phases, for example in an ion-exchange column, and the separated particles move in opposite directions. There is no focus in this method.

There are various methods of separation by focusing particles in a dissipative medium (see Evans LL, Burns, M.V. Solute Focusing Techniques for Bioseparations // Bio-Technology. - 1995. - Vol.13. - Iss.1. - p.46 -52). All the various focusing methods for particle separation and concentration (chromatographic focusing, isoelectric focusing, and other methods described, for example, in this review article) have the following general features. When focused, the particles rush to some points or areas inside the vessel or sample. Moreover, the particles approach these points or focus areas from all sides, and the particles remain in the focus area, i.e. the distribution of particles does not blur due to diffusion (as long as the fields that focus are in effect), although of course due to diffusion the distribution of particles around a point or region of focus has a finite width. And there is a stationary distribution of particles concentrated inside the vessel around the point or area of focus. Moreover, focusing is not a process of force attraction to the center, which would be at the focusing point. In addition, for different particles, these points or focus areas can be in different places of the vessel or sample, and thus the separation of the particles of the solution or mixture can occur.

It should be noted that in the technique the expression "particle focusing" is used in several meanings. It is used in electronic optics; In this case, dissipation (caused, for example, by collisions of focused particles with air molecules) interferes, and therefore focusing is carried out in vacuum, i.e. in a non-dissipative environment. The phrase "particle focusing" is also used in the field of separation of substances, electrophoresis and chromatography. In this case, focusing is carried out in a dissipative medium. The word "dissipative" is used to indicate in what sense the word "focusing" is used and that we are not talking about focusing particles in a vacuum. And, in addition, the proposed method only works in a dissipative environment. It is understood that in the equations of motion the friction term is much larger than the inertial term. In such a medium, velocity is proportional to force (in small fields), and in a medium without dissipation, acceleration is proportional to force. In the proposed method, mobility (which is inversely proportional to friction) plays an important role. In the proposed method, dissipation does not interfere with focusing, and the presence of dissipation is a condition for focusing in the sense used in this application (when there is no dissipation, you cannot write formulas for moving particles as they are written below).

During isoelectric focusing in a system with a nonuniform pH, particles (whose charge depends on pH) in the electric field are focused at the points where the charge changes sign (see Stepanov A.V., Korchemnaya E.K. Electromigration method in inorganic analysis. - M. : Chemistry, 1979).

The disadvantage of this method is that it is possible to focus only particles whose properties depend on the pH of the solution.

The closest method of the same purpose to the claimed invention is essentially electroconvective focusing, in which particles in a dissipative medium are focused using a field that moves them. With electroconvective focusing, particles move in an inhomogeneous medium using two opposing forces caused by the electric field and the field of fluid flow. These forces have different gradients and directions, and focusing occurs at points where the total force is zero (see O'Farrell R.N. Separation techniques based on the opposition of two conteracting forces to produce a dynamic equilibrium // Science. - 1985. - Vol.227. - P.1586-1589. Koegler WS, Ivory CF Focusing proteins in an electric field gradient // Journal of Chromatography A. - 1996. - Vol.229. - P.229-236).

The disadvantage of this method is that only certain types of particles can be focused, for example particles that can be moved using an electric field and a fluid flow field.

The technical result of the invention is the creation of a general method for focusing particles in a dissipative medium. Different particles can be focused in different places. Those. The method allows you to separate different particles. The method allows to focus particles on the boundary between two media. The method allows you to clean the solution or sample from impurities.

The specified technical result in the first embodiment of the method is achieved by the fact that in the known method of focusing particles in a dissipative medium using a field that moves them, to carry out focusing, these particles are moved in different directions using an alternating field and simultaneously changing the parameters of the particles or medium that determine the speed of particles by an additional variable independent effect, while the variable effect or medium is heterogeneous, and the parameters of the particles or medium change so so that the medium contains particles for which the average velocity along one of the x, y, z axes for the period of the alternating field was greater than zero, and particles for which the average velocity along one of the x, y, z axes for the period of the alternating field was less than zero.

It is proposed that this field is an electric or magnetic, or a vibrational field, or a particle entrainment field, or a mobile phase flow field in chromatography.

To change the properties, it is proposed to use an electric or magnetic, or a vibration field, or heat supply, or pressure, or radiation.

The specified technical result in the second variant of the method is achieved by the fact that in the known method of focusing particles in a dissipative medium using a field that moves them, to focus these particles are moved using an alternating field in a medium with a cell structure, with each cell being materials through which the particles pass, and it is possible to create a gradient of the properties of the cells along a sequence of cells, with the particles moving through a sequence of cells and, in each cell e particles are passed through materials with different properties when moving in different directions, and the parameters of the particles or medium are changed so that particles are present in the medium for which the average velocity along one of the x, y, z axes for the period of the alternating field is greater than zero, and particles for which the average velocity along one of the axes x, y, z during the period of the alternating field was less than zero.

It is proposed that this field is an electric or magnetic, or a vibrational field, or a particle entrainment field, or a mobile phase flow field in chromatography.

The method consists in the fact that the particles are moved in different directions using an alternating field, the average value of which is not necessarily equal to zero, and synchronously with the alternating field change the particle parameters that determine the speed of movement, for example, change the mobility, friction coefficient, charge, particle shape, conductivity of the medium, the ratio between the number of particles in the mobile and stationary phases in chromatography. The presence of an additional action to the field and independent of the field means that both the field and the action are applied to the system, and the experimenter can independently control them. During the focusing process, in each period the particles move to and from the focusing region, and on average over the period the particles approach the focusing region. To focus particles, it is necessary that they average the period approach the focusing area from different sides. In this case, some components of the period-averaged particle velocity, which are located on different sides of the focusing region, have different signs. Therefore, the parameters of the particles or medium are changed so that particles are present in the medium for which the average velocity along one of the x, y, z axes for the period of the alternating field is greater than zero, and particles for which the average velocity along one of the x axes, y, z during the period of the alternating field was less than zero. In the case of defocusing, the particles move away from the defocusing region over the period average, and also some components of the velocity-averaged particle velocity, which are on different sides from the defocusing point, have different signs.

The word "field" is understood in a broad sense. This can be an electric field, a magnetic field, a field of entrainment by a gas or liquid, a field of entrainment by a mobile phase in chromatography, a field of vibrations, a field of voltage in a solid. If a spatially inhomogeneous field is required for particle motion (for example, for dipoles), then particles are moved using a field with a time-varying inhomogeneity. The word "particle" is understood as any object capable of moving with the help of this field, such as atoms, molecules, colloidal particles, macroscopic particles, defects in crystals. The "mobility" μ is understood as μ = ν / E, where E is the field in the broad sense and ν is the particle velocity.

The period of the variable field is selected from the following conditions. In one half-life, the particles must travel much less than the size of the vessel or sample. The width of the spatial distribution of particles in the focusing region cannot be less than the path that the particle travels in one half-cycle. Within one period, the properties of the medium must have time to change. During chromatography, the particles must pass from the mobile phase to the stationary phase and vice versa several times in one period.

A variable field does not have to be strictly periodic. For example, you can change the "period" of an alternating field during an experiment.

To focus the particles, the properties of the particles or medium must be heterogeneous, since then the displacement of the particle in one period depends on the place where it is located.

It is assumed that the parasitic thermal convection motion of particles is negligible.

In a first embodiment of the invention, the parameters of the particles or medium are altered by an alternating additional action. Changes in these parameters can be achieved by oscillations of temperature, pressure, sound intensity, radiation, fields, composition of the mobile phase in chromatography, etc. The environment must reproducibly change its properties with additional exposure.

In a second embodiment of the invention, the parameters of the particles or medium are changed in each cell by replacing the materials through which the particles pass through the displacement of these materials or by changing the path along which the particles go.

A change in the properties of particles synchronous with an alternating field provides an additional opportunity to control the process of particle motion and allows particles to move in directions that depend on the properties of particles at each point in the medium.

The term "synchronous" is used in the same sense as in the theory of oscillations. Synchronous vibrations (vibrations) - two or more simultaneously occurring periodic vibrations (vibrations) having equal frequencies (definition of GOST 24346-80).

Figure 1 shows the temperature distribution of T ₁ (x), and T ₂ (x) along the sample in Example 1.

Figure 2 shows the mobility μ ₁ (x) and μ ₂ (x) in Example 1.

Figure 3 shows the displacement δx ₁ (x) and δx ₂ (x) in Example 1.

Figure 4 shows the total displacement in one period δ (x) in Example 1.

Figure 5 shows a possible temperature distribution along the sample used to focus particles inside the sample near the edges of the sample.

6 and 7 schematically depict the cell medium used in the second embodiment of the invention.

In Fig.6, where 1 is a fixed plate, 2 is a movable plate, 3 is a liquid, several medium cells are presented in the case of particle migration in the liquid and when the materials through which the particles pass are periodically replaced by inserting and removing the plates.

In Fig. 7, where 4 are valves that determine the path of the particles, 5 are valves for the inlet of the mixture and the release of pure substances, one medium cell is shown in the case when the particles periodically change the path using the valves and pass alternately through material 6 or through material 7 .

The method is illustrated by specific examples.

Example 1. One-dimensional particle motion and particle focusing.

The following calculation is applicable, for example, when ions move in a cell with a liquid or gel during electrophoresis, when ions move in a dielectric or in a semiconductor during electromigration in solids. In these cases, E is the electric field strength. The calculation is applicable, for example, also when molecules move in chromatography. In this case, E is the velocity of the mobile phase, which carries molecules away.

All materials are ordinary materials that are used in conventional electrophoresis, electromigration, chromatography.

In the proposed method, the particles move using an alternating field. Let the field be such that for one period of time t ₁ + t _{2 it} takes the value E ₁ > 0 during the time t ₁ and for the time t ₂ it takes the value E ₂ <0. These field values are set by the experimenter using a source. In the case of electrophoresis or electromigration, this is a source of electrical voltage or current, in the case of chromatography it is a compressor.

In the proposed method, in parallel with the alternating field, the parameters of the particles or the medium are changed, which determine the particle velocity by an additional variable independent effect. In this case, such a parameter is the mobility of particles. As you know, the mobility of particles depends on temperature. Using the heater located along the cell, the experimenter sets the temperature distribution along the cell. Here, the heater carries out an additional effect, provides heat input. Let the experimenter alternately set such temperature distributions: during time t _{1 the} temperature is equal to T ₁ (x) and during time t _{2 the} temperature is equal to T ₂ (x). The x axis is directed along the cell, along the movement of particles. The temperature distribution T ₁ (x) and T ₂ (x) shown in figure 1 in arbitrary units. Let with these temperature distributions the mobility for the particles used during time t ₁ is equal to μ ₁ (x), and for time t ₂ mobility is equal to μ ₂ (x). The functions μ ₁ (x) and μ ₂ (x) are shown in FIG. 2 in arbitrary units. Here, temperature and mobility depend on x, since, by assumption, the variable action or medium is heterogeneous.

Then, in the first half-cycle for a time t _{1, the} particle (for particles with a positive charge, if E ₁ is an electric field) is shifted by a distance along the x axis

δx ₁ (x) = μ ₁ (x} E ₁ (x) t ₁ ,

in the second half-period, for a time t _{2, the} particle is displaced by a distance along the x axis

δx ₂ (x) = μ ₂ (x) E ₂ (x) t ₂

The displacements δx ₁ (x) and δx ₂ (x) are shown in figure 3 in arbitrary units. Here the displacements are given when E ₁ (x) = 1, E ₂ (x) = - 1, t ₁ = t ₂ = 1 in arbitrary units.

The total offset in one period is

δx (x) = δx ₁ (x) + δx ₂ (x)

The full offset for one period is shown in Fig.4. At point x _{F, the} total displacement in one period is zero. To the left of the point x _{F, the} total displacement is positive (i.e., the displacement occurs to the right), to the right of the point x _{F, the} total displacement is negative (i.e., the displacement to the left), so the particles rush to the point x _F , this point is the focus point (focusing). Thus, particles moving back and forth in each period gradually approach the focal point. The position of the focus point depends on the additional effect (in this case, on the temperature distribution) and on the field values (on E ₁ t ₁ and E ₂ t ₂ ), i.e. You can choose the position of the focus point as you like.

In Fig. 1, the functions T ₁ (x) and T ₂ (x) intersect and, at E ₁ t ₁ = -E ₂ t ₂ , the focus point coincides with the intersection point of T ₁ (x) and T ₂ (x). When E ₁ t ₁ ≠ -E ₂ t ₂ the focus point will not be at the intersection of T ₁ (x) and T ₂ (x). In the general case, the functions T ₁ (x) and T ₂ (x) do not have to intersect. Then the focus point will not be at E ₁ t ₁ = -E ₂ t ₂ , but at other values of E ₁ t ₁ and E ₂ t ₂ .

Different particles generally have different focus points. In this way, different particles can be separated. You can also select field values (E ₁ t ₁ and E ₂ t ₂ ) such that different particles have the same focus points. In this example, when E ₁ t ₁ = -E ₂ t ₂ different particles have the same focus points. At E ₁ t ₁ ≠ E ₂ t ₂ they have different focus points if condition (1) is satisfied (see below).

In each case of the application of the method, one needs to know which field moves these particles, what influences affect mobility (or other parameters of particles or media that determine the speed of particles) and know how these influences affect mobility or parameters that determine particle speed. Then it is possible to determine the values of the fields and additional actions necessary for focusing in a particular case.

Consider the necessary condition that particles A and B have different focus points.

For one period t ₁ + t _2, particle A (for particles with a positive charge, if E ₁ is an electric field) is shifted by a distance

and particle B with a positive charge is displaced by a distance

At the focus point, the offset in one period is zero. When particles A and B are focused simultaneously at the point x, we have

This system of equations for fields has nonzero solutions only when its determinant is zero, i.e. a necessary condition that particles A and B are not focused simultaneously at the point x:

Condition (1) is not satisfied only in exceptional cases. If (1) is not satisfied in a given experiment, other conditions of the experiment can be chosen.

In the general case, in three-dimensional space and for an arbitrary dependence of the field and mobility on time and coordinates, the average speed of a spherically symmetric particle with variable mobility in an alternating field in an isotropic medium:

,

,

where the horizontal line means averaging over the period of the variable field at a constant r.

In deriving this expression, it is assumed that in one period the particles are displaced by a small distance relative to the size of the inhomogeneity μ (r, t) or E (r, t).

At the focal points v ⁰ (r) = 0 and near the focal points, the particles approach them on average over a period.

Example 2. The focusing of particles in a one-dimensional vessel, when the variable mobility linearly depends on x. Let in each period of duration t ₁ + t ₂ during the time t _{1 the} field takes the value E ₁ , the mobility takes the value μ ₁ (x) = μ ₀₁ + α ₁ x, and during the time t _{2 the} field takes the value E ₂ , the mobility takes the values μ ₂ (x) = μ ₀₂ + α ₂ x (for x such that μ ₁ (x) and μ ₂ (x) are positive). For simplicity, we assume that the field is homogeneous. The equation describing the motion of a particle with a positive charge has the form

.

.

The solution to this equation is:

where t is time;

x (0) is the initial position of the particle;

m = (μ ₀₁ E ₁ t ₁ + μ ₀₂ E ₂ t ₂ ) / t ₀ ;

n = (α ₁ E ₁ t ₁ + α ₂ E ₂ t ₂ / t ₀ .

The particle velocity is zero at x ⁰ = -m / n. For particles with a positive charge, this is the focus point if n <0, and the defocus point (in mathematics this is a repeller) if n> 0. For particles with a negative charge, the opposite inequalities hold. Particles with different m / n focus in different places. When separating substances, one can accelerate the process of isolating one type of particle by placing the mixture in the focusing area of these particles. The remaining particles are removed from this area.

It can be shown that the width of the spatial distribution of particles due to thermal motion is

where δ = mω-un, u = (μ ₀₁ t ₁ + μ ₀₂ t ₂ ) / t ₀ , ω = (α ₁ t ₁ + α ₂ t ₂ ) / t ₀ , k is the Boltzmann constant, k = 1, 38 × 10 ^-23 J / K.

In deriving this expression, it is assumed that the particle displacement in one period is much smaller than this width.

In these formulas, the change in conductivity through an additional effect was not taken into account. When E is an electric field, it must be taken into account that the additional effect changes the conductivity and, therefore, changes the electric field. The spatially inhomogeneous effect creates a conductivity gradient and a field gradient. This affects the position of the focus points and the width of the distribution function. In the following specific example, the temperature dependence of conductivity is taken into account in the calculation.

Consider a specific example. Suppose that in a cuvette with water 2 m long in the first half-cycle, the electric field along the cuvette is equal to E ₁ = 100 V / m, the temperature is constant and equal to T = 18 ° C. In the second half-period, the potential drop in the cell is selected from the condition that (j ₂ / j ₁ ) = - 1, 2, where j ₁ and j ₂ are the electric current density in the first and second half-periods, and let t ₂ = t ₁ . (Here the density of the electric current is set, and not the electric field, because the electric field is inhomogeneous). In the second half-period, a temperature gradient is set: at the left end at x = 0 the temperature is T = 26 ° C, and at the right end at x = 2 m the temperature is T = 18 ° C. The calculation, taking into account changes in ion mobility and water conductivity with temperature, shows that Tl ⁺ , Ca ²⁺ , Co ²⁺ , Pb ^{2+ ions are} focused at points x = 0.78 m; 0.93 m; 0.59 m; 0.74 m, respectively, and the width of the distribution function is 0.019 m; 0.013 m; 0.014 m; 0.014 m, respectively. To obtain these results, we used the mobility ratios at temperatures T = 26 ° C and T = 18 ° C for these ions (see the Handbook of Electrochemistry / Ed. AM Sukhotina. - L., - 1981. - Ch. 3) and the ratio conductivity of water at these temperatures (see D. Dovosh. Electrochemical constants. - M., - 1980).

принимает значения

и

и

принимает значения

и

. И соответственно проводимость принимает значения

,

, и

,

. Если проводимость равна

для среды α и σ^b для среды b, то в сосуде с постоянным сечением значения поля в двух средах удовлетворяют соотношению E^a/E^b=σ^b/σ^a. Для фокусировки частиц с положительным зарядом на границе необходимо, чтобыExample 3. Particle focusing in an inhomogeneous medium. In an inhomogeneous medium, a uniform effect causes an inhomogeneous change in properties. In such a medium for focusing particles, the additional effect may be uniform. For example, you can focus (or defocus) particles on the boundary between media a and b. Let the boundary be perpendicular to the x axis and the field directed along the x axis. Let a variable effect periodically change mobility and conductivity. For example, a variable effect changes the temperature and it alternately takes on the values of T ₁ and T ₂ in the time intervals t ₁ and t _2, respectively, while the mobility

takes values

and

and

takes values

and

. And accordingly, the conductivity takes on values

,

, and

,

. If the conductivity is equal to

for medium α and σ ^b for medium b, then in a vessel with a constant cross section the field values in two media satisfy the relation E ^a / E ^b = σ ^b / σ ^a . To focus particles with a positive charge on the boundary, it is necessary that

Suppose that the medium a is at lower x values. These inequalities can always be satisfied if

и

т.е. когда подвижность не изменяется, а изменяется только проводимость.These inequalities can be satisfied even if

and

those. when mobility does not change, but only conductivity changes.

To focus particles with a negative charge, the opposite inequalities are fulfilled. At the boundary, particles with positive and negative charges can be concentrated simultaneously.

It can be shown that the degree of decay of the particle distribution function a in the medium a is

частицы находятся вблизи границы в основном в среде

.A similar expression can be written for environment b. You can control the ratio of the number of particles in two environments. When

particles are near the boundary mainly in the medium

.

и

задаются экспериментатором. Пусть температура Т принимает значения Т₁=640К, T₂=625К и при этом подвижности принимают значения

As an example, we consider the focusing of a lithium ion at the interface between Si (medium α) and GaAs (medium b). The temperatures T ₁ and T ₂ and the values of the electric field

and

are set by the experimenter. Let the temperature T takes the values T ₁ = 640K, T ₂ = 625K, and at the same time the mobilities take values

и

. (см. Landolt-Börnstein, 6 th Edition, II Band, 6. Teil, 1959 и Landolt-Börnstein, New Series, Vol.17a, 1982). Остальные параметры принимают значения

Тогда

Если

и остальные параметры остаются прежними, тогда

(see Physical quantities: Reference book / A.P. Babichev, N.A. Babushkina, AMBratkovsky and others; edited by I.S. Grigoriev, E.Z. Meilikhov. - M., 1991, - Ch. 17 ), and conductivity take values

and

. (see Landolt-Börnstein, 6th Edition, II Band, 6. Teil, 1959 and Landolt-Börnstein, New Series, Vol.17a, 1982). Other parameters take values

Then

If

and other parameters remain the same, then

,

,

в произвольных единицах. Пусть остальные параметры принимают значения

элементарных зарядов,

Тогда

Если

и остальные параметры остаются прежними, тогда

В более сильном поле или, если заряды бóльшие, то частицы могут быть сконцентрированы в меньших областях. Здесь для простоты предполагалось, что проводимости одинаковые в двух средах.Consider focusing colloidal particles. Let T take the values T ₁ = 310K, T ₂ = 290K at the boundary in a medium with colloidal particles, while the mobilities take values

,

,

in arbitrary units. Let the remaining parameters take values

elementary charges

Then

If

and other parameters remain the same, then

In a stronger field, or if the charges are larger, then the particles can be concentrated in smaller areas. Here, for simplicity, it was assumed that the conductivities are the same in two media.

You can also, choosing the desired field values, remove particles from the boundary between the media. Thus, it is possible to clean the border of some impurities.

Example 4. It is also possible to independently move non-interacting particles of n different sorts in arbitrary directions in a field that takes in one period N the values of E ₁ , E ₂ , ..., E _N in the time intervals t ₁ , t ₂ , ..., t _N , while the mobility of each particle takes respectively N values. With one-dimensional motion in one medium, in the general case, N = n. For focusing (or defocusing) particles on a flat boundary between two media in the general case, N = 2n. The determinant of the Nth order, similar to determinant (4), must be nonzero.

This can be achieved by changing mobility through independent influences. For example, you can change the temperature, pressure, irradiate with light, influence fields, etc. If the mobility depends nonlinearly on the magnitude of the effects, then the additional effect can take several values in series. In particular, it is possible in one period to move particles sequentially at several temperatures. Also, if the mobility depends on the frequency of the incident light, then it is possible to irradiate with light of different frequencies.

Thus, it is possible, for example, to select particles that are collected at the boundary (or removed from the boundary) when there are different ions in the semiconductor in Example 3.

Example 5. The method allows you to create a particle distribution inside a viscous medium, determined by additional exposure, such as light. Particles move by means of an alternating field (for example, electric, magnetic, vibrational), and light changes the mobility of these particles. The distribution of particles depends on the distribution of light intensity.

Thus, instead of changing the temperature with the heater in Examples 1, 2, 3, it is possible to change it with the help of light and obtain a particle distribution determined by the distribution of light intensity.

находятся вблизи краев образца. И пусть E₁t₁=-E₂t₂ и Е₁>0. Тогда частицы с положительным зарядом, для которых подвижность увеличивается при увеличении температуры, и частицы с отрицательным зарядом, для которых подвижность уменьшается при увеличении температуры, собираются в точке х_b; для них точка

является точкой дефокусировки. Аналогично, точка

является точкой фокусировки для частиц с отрицательным зарядом, для которых подвижность увеличивается при увеличении температуры, и для частиц с положительным зарядом, для которых подвижность уменьшается при увеличении температуры; для них точка х_b является точкой дефокусировки. Примеси, находящиеся в середине образца, собираются у краев в точках

Примеси, находящиеся у краев вне точек

собираются в точках

или удаляются из образца. Следует отметить, что в каждый период может быть интервал времени, в течение которого устанавливается нужное распределение температуры; в этом интервале поле может отсутствовать.Example 6. The method allows you to clean gases, liquids, solids from impurities. It is possible to create focusing areas inside the sample (or vessel) near the edges, where impurities are concentrated, and which do not pass impurities into the middle of the sample. Impurities from the middle of the sample are focused inside the sample near the edges. External impurities are concentrated at the nearest edge, or, if this edge is a defocusing point for them, then they are removed. For example, let the temperature distribution along the sample in each period have the form T ₁ (x) over time t ₁ and the form T ₂ (x) over time t ₂ . The functions T ₁ (x) and T ₂ (x) are shown in FIG. Temperature distributions are set by the experimenter using a heater. Points

are near the edges of the sample. And let E ₁ t ₁ = -E ₂ t ₂ and E ₁ > 0. Then particles with a positive charge, for which mobility increases with increasing temperature, and particles with a negative charge, for which mobility decreases with increasing temperature, are collected at point x _b ; for them a point

is the defocus point. Similarly, point

is the focus point for particles with a negative charge for which mobility increases with increasing temperature, and for particles with a positive charge for which mobility decreases with increasing temperature; for them, the point x _b is the defocus point. Impurities in the middle of the sample are collected at the edges at points

Impurities at the edges outside the points

gather at points

or are removed from the sample. It should be noted that in each period there may be a time interval during which the desired temperature distribution is established; in this interval the field may be absent.

Also, in a three-dimensional sample, it is possible to create areas where some impurities and defects are concentrated, or areas free of some impurities or defects. These impurities and defects must move under the influence of a field (for example, an electric field or a stress field) and their “mobility” must depend on the additional effect (for example, the value of “mobility” depends on temperature or sound intensity).

Thus, it is possible to purify liquids from certain impurities and solids from certain impurities or defects.

Example 7. The medium can have a discrete structure, consist of cells, and the change in the environment is carried out by changing these cells or changing the path of the particles in these cells.

The medium may consist of a sequence of plates through which particles pass. The plates are periodically inserted and taken out so that there is no mixing of particles of distant cells. Figure 6 shows an example of such a medium in the case of electromigration (electrophoresis). The plates 1 are fixed, the plates 2 are periodically lowered into the liquid 3 and rise synchronously with a change in the direction of the electric field. All liquids, plate materials are ordinary liquids, materials that are used in ordinary electromigration. Plate materials are porous materials through which particles pass.

The procedure is as follows: In the first half-cycle, a positive electric voltage is applied between the ends of the cell where the liquid is located. When this plate 2 is raised. In the second half-cycle, negative electric voltage is applied between the ends of the cell. When this plate 2 is omitted in the solution. Moreover, the plates are such that a gradient is created of the properties of the sequence of cells (as in FIG. 2 of Example 1). In each period, these actions are repeated until the particles are focused.

In the case of chromatography, the cell may have the form shown in Fig.7. The mobile phase in chromatography carries particles, it is the "force" by which particles move. The speed of the mobile phase is the magnitude of the field.

The procedure is as follows. In the first half-period, the mobile phase (liquid, gas) flows to the right and it passes, for example, through the upper material 6 in each cell of the cell sequence. In the second half-period, the mobile phase moves to the left and passes through the lower material 7 in each cell of the cell sequence. Moreover, the materials of the cells are such that a gradient is created of the properties of the sequence of cells (as in FIG. 2 of Example 1). In each period, these actions are repeated until the particles are focused.

Materials 6 and 7 are conventional materials that are used in conventional chromatography.

Valves 4 determine the path of the mobile phase and focusable particles according to material 6 or material 7. Valves 5 serve to inlet the mixture and release pure substances. The focusing process occurs as in a continuous medium, but instead of changing the properties of the medium with an additional effect, in each cell the materials through which the particles pass, i.e. instead of changing the environment, replace the environment.

The laws of particle motion in a cell medium are the same as in a continuous medium, if we assume that in the formulas the field is the effective field and the mobility is the effective mobility of particles in an effective inhomogeneous continuous medium obtained from a discrete medium by averaging over several neighboring cells. This averaging is possible if in each period the particles pass through several cells. For particle focusing, it is necessary that this continuous effective medium be inhomogeneous, i.e. cell properties must vary along a sequence of cells. The peak in the distribution of focused particles occupies several cells.

You can create a two-dimensional discrete medium.

Example 8. The method allows you to focus macroscopic particles using vibrations.

Let, for example, particles lie on a flat horizontal rough surface, and the surface oscillates in the plane of the surface. A system is used in which vibration transfer can be carried out (see II Blekhman, Vibration Mechanics. - M .: Fizmatlit, 1994. - Part 3) and the coefficient of friction of particles depends on some additional effect. The coefficient of friction of particles should change synchronously with changes in the vibration field, in which the direction of the vibrational transfer of particles changes. The period of the alternating vibrational field is much larger than the period of vibrations. Changing the direction of the vibrational transfer of particles is carried out by changing the asymmetry of vibrations (vibrational transfer of particles requires asymmetry of vibrations). By varying the coefficient of friction nonuniformly with the help of heat, magnetic field, lighting, etc., it is possible to focus particles and separate them according to their respective properties. For example, it is possible to separate particles of a similar shape in size (particles with a larger size have a longer relaxation time), in color (particles of different colors can heat up differently under lighting) in a system in which the coefficient of friction of particles depends on temperature.

For complete separation of particles, it may be necessary to use the method several times using different influences.

It should be noted that vibrations (symmetrical) or sound can serve as an additional effect when particles move in an alternating field of a different nature. In this case, the intensity of vibrations or sound is changed synchronously with the alternating field.

для бензола

. Используя эти значения фактора удержания можно получить координаты точки фокусировки из формул Примера 2 в колонке длины L=1 м. Для фенола

для бензола

Можно показать, что полуширина функции распределения частиц приблизительно равнаExample 9. An example of the use of the method in liquid chromatography. The speed of the molecules along the column during liquid chromatography is ν = u / (1 + k), where k is the retention factor, u is the flow rate of the mobile phase. Let focusing be carried out in a column of length L. Let the flow rate of the mobile phase take the value u ₁ = 1> 0 (in arbitrary units) in the first half-cycle and set the temperature gradient: at the left end at x = 0, the temperature is T = 130 ° C, and at the right end, at x = L, the temperature is T = 90 ° C. In the second half-cycle, the flow rate of the mobile phase takes the value u ₁ = -1.1 <0 (in arbitrary units) and the temperature is constant and equal to T = 90 ° C and let t ₂ = t ₁ . The values of the retention factor are taken from the article "Zhu S., Goodall DM, Wren SAC Elevated temperature HPLC: principles and applications to small molecules and biomolecules // LC GC North America. - 2005. - v.23 - 54-72", where values of the retention factor at different temperatures in a column of ZirChrom-PBD and liquid - superheated water. For phenol

for benzene

. Using these values of the retention factor, one can obtain the coordinates of the focusing point from the formulas of Example 2 in a column of length L = 1 m. For phenol

for benzene

It can be shown that the half-width of the particle distribution function is approximately equal to

, где α - коэффициент порядка нескольких размеров зерен пористой среды колонки. Другие параметры определены в Примере 2. Пусть α=2·10^-4 м, тогда полуширина распределения для фенола равна l^ph=0,12 м и для бензола равна l^b=0,08 м.In the conclusion, it was used that the dispersion coefficient is

where α is a coefficient of the order of several grain sizes of the porous medium of the column. Other parameters are defined in Example 2. Let α = 2 · 10 ^-4 m, then the half-width of the distribution for phenol is l ^ph = 0.12 m and for benzene is l ^b = 0.08 m.

If the peaks for different molecules overlap under certain conditions, it is necessary to focus at other values of the parameters (mobile phase velocities u ₁ , u ₂ , time intervals t ₁ , t ₂ , temperature, column length, and other parameters characterizing the usual chromatographic process).

Claims (5)

1. A method of focusing particles in a dissipative medium using a field that moves them, characterized in that these particles move in different directions using an alternating field, and synchronously with the alternating field change the particle or medium parameters determining the particle velocity by an additional variable independent effects, while the variable exposure or medium is heterogeneous, and the parameters of the particles or medium are changed so that particles are present in the medium for which the average velocity along one of the x axes , y, z for the period of the alternating field was greater than zero and particles for which the average velocity along one of the axes x, y, z for the period of the alternating field was less than zero. 2. The method according to claim 1, characterized in that this alternating effect is an electric or magnetic or vibrational field or heat input or pressure or radiation. 3. The method according to claims 1 and 2, characterized in that this field is an electric or magnetic or vibrational field or a particle entrainment field or a mobile phase flow field in chromatography. 4. A method of focusing particles in a dissipative medium using a field that moves them, characterized in that these particles are moved using an alternating field in a medium with a cell structure, with each cell containing materials through which the particles pass and it is possible to create gradient of the properties of cells along a sequence of cells, with the particles moving through a sequence of cells and, in each cell, particles are passed through materials with different properties when moving in different directions, and The particles or medium ores are changed so that particles are present in the medium for which the average velocity along one of the x, y, z axes for the period of the alternating field is greater than zero, and particles for which the average velocity along one of the x, y, z axes for the period of the variable field was less than zero. 5. The method according to claim 5, characterized in that this field is an electric or magnetic or vibrational field or a particle entrainment field or a mobile phase flow field in chromatography.

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