CN108872290B - Method and device for improving resolution by automatic rotation of small nuclear magnetic resonance spectrometer - Google Patents
Method and device for improving resolution by automatic rotation of small nuclear magnetic resonance spectrometer Download PDFInfo
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- CN108872290B CN108872290B CN201810374684.XA CN201810374684A CN108872290B CN 108872290 B CN108872290 B CN 108872290B CN 201810374684 A CN201810374684 A CN 201810374684A CN 108872290 B CN108872290 B CN 108872290B
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- G01N24/00—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects
- G01N24/08—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects by using nuclear magnetic resonance
Abstract
The invention relates to a method for automatically rotating and improving spectrogram resolution of a low-field small-sized nuclear magnetic resonance spectrometer and an automatic sample tube rotating device for automatically rotating and improving spectrogram resolution of the low-field small-sized nuclear magnetic resonance spectrometer, which further improves the magnetic field uniformity of the low-field nuclear magnetic resonance spectrometer under the condition of not changing a magnet and a shimming coil of the existing system, indirectly drives the sample tube to stably rotate by controlling a motor, extracts parameter data related to the resolution of the nuclear magnetic resonance spectrometer at different rotating speeds, carries out comparison analysis on parameters related to the resolution of the magnetic resonance experiment and the spectrogram, iteratively calculates the corresponding rotating speed under the optimal experiment parameter to obtain the rotating speed with the best effect of overcoming the magnetic field nonuniformity, then automatically adjusts the system to operate at the rotating speed in real time, eliminates the difference of the sample and the experiment parameter, and counteracts the magnetic field nonuniformity to a certain degree, the optimal effect of the experiment is obtained to the maximum extent, a large amount of test and comparison work of operators is avoided, and the experiment efficiency is greatly improved.
Description
Technical Field
The invention relates to the field of research and development of nuclear magnetic resonance instruments, in particular to a method for automatically rotating and improving spectrogram resolution of a low-field small nuclear magnetic resonance spectrometer and an automatic sample tube rotating device for automatically rotating and improving spectrogram resolution of the low-field small nuclear magnetic resonance spectrometer.
Background
In order to improve the sensitivity and resolution of a nuclear magnetic resonance instrument to a detection spectral line of a detected sample, a proper magnetic field strength is required and the uniformity of the magnetic field is ensured, so that a high-resolution spectrogram of the sample is obtained. In the hardware design, the design of a main magnet and the regulation and control of a shimming coil are mainly relied on, the magnet is designed by increasing the magnetic field intensity and improving the magnet processing technology, the shimming coil is designed by increasing the high-order shimming of the shimming coil and is realized by adopting an effective shimming algorithm.
To further overcome the inhomogeneity of the magnetic field after the magnet and shim coil designs were fixed, the sample tube rotation method was first introduced in 1954, in the literature "f.bloch, phys.rev.,94, (1954), 496", indicating that rotating the sample can improve the resolution of the nuclear magnetic spectrometer.
At present, a large-scale high-field superconducting nuclear magnetic resonance system generally utilizes air turbine power to enable a sample tube to be measured to rotate in a specified speed range, and a magnetic field of a sample is uniform in a mode of rotating the sample, so that the nonuniformity of the magnetic field on a plane perpendicular to a rotating shaft is overcome. Typical large superconducting nuclear magnetic resonance spectrometers of foreign Bruker, Agilent and internal Wuhan Zhongke Oxford spectral technology Limited all use an air compressor to control a rotation scheme to rotate a sample tube. In low field nuclear magnetic instruments, such as the low field permanent magnet nuclear magnetic instrument of atlanto scientific and education equipment ltd, shanghai, a turbine air control device was employed.
The research on sample tube rotating devices by related patents and documents at home and abroad mainly adopts a turbine pneumatic control rotating method, for example: U.S. Pat. No. 4, 4275350, entitled Sample Spinning mechanics for NMR Probes, was issued in 1981, and describes the rotation of a rotor by an aerodynamic device; U.S. patent "Hightemperture NMR sample spin", 1993 (U.S. patent No. 5202633), wherein the device is a high temperature magic angle spinning air-driven spinning device; in a U.S. patent "Sample Spinning mechanics for NMR Probes" (U.S. patent No. 9778332B2) issued in 2017, the pneumatic turbine rotation controller adopts an algorithm controllable pulse form to control the rotation speed of a Sample tube; the literature "Deuterium NMR in Solids with a Cylindrical magnetic, Journal of magnetic Resonance,1980,41(3): 440-; the references "Implementation of Fuzzy Self-tuning integral Derivative Control on Sample-tube screw Control System in nuclear magnetic Resonance Spectrometer, Chinese Journal of Analytical Chemistry,2011,39(4): 506-.
However, since the air compressor and the complicated air path system are required to be configured in the turbine air control rotation mode, the nuclear magnetic resonance equipment of the portable small permanent magnet is limited by the volume, the structure and the cost of the magnet, and an air turbine rotation device cannot be adopted.
In the sample tube rotating device adopted by the nuclear magnetic resonance system in the prior art, the rotating speed of the sample tube is manually set by an operator, and the rotating speed under the optimal result cannot be obtained through feedback calculation according to the obtained experimental result. The rotation speed set in the experiment may not be the rotation speed at the best spectrogram resolution that can be achieved, and noise introduced due to the rotation side band peaks and high rotational instability generated by different rotations has a large influence on the experimental results.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a method for automatically rotating and improving the spectrogram resolution of a low-field small nuclear magnetic resonance spectrometer, which can automatically adjust the rotating speed of a rotating mechanism and obtain the optimal spectrogram resolution, and an automatic sample tube rotating device which is simple in structure, low in cost, capable of offsetting the influence of magnetic field nonuniformity to a certain extent, automatically controlling the rotation of a sample tube according to an experimental spectrogram result and improving the experimental efficiency, and is used for automatically rotating and improving the spectrogram resolution of the low-field small nuclear magnetic resonance spectrometer.
The technical scheme of the invention is as follows:
a method for automatically rotating and improving spectrogram resolution of a low-field small nuclear magnetic resonance spectrometer is characterized in that a rotating mechanism drives a sample tube to rotate; obtaining a corresponding spectrogram resolution ratio based on a nuclear magnetic experiment result of the current rotating speed; controlling the rotating mechanism to change the speed to obtain the spectrogram resolution corresponding to the changed speed; and maintaining the speed change of the rotating mechanism until the optimal spectrogram resolution is obtained, and controlling the rotating mechanism to drive the sample tube to rotate at the rotating speed corresponding to the optimal spectrogram resolution.
The strategy for controlling the rotating mechanism to automatically change the speed is as follows: the method comprises the steps of firstly setting a noise threshold, filtering signals lower than the threshold, then carrying out a nuclear magnetic resonance experiment, collecting the nuclear magnetic resonance signals, obtaining resolution, taking the resolution as a first group of indexes, repeating the experiment, comparing the quality of spectrogram resolutions at different speeds before and after the experiment, if the spectrogram resolution corresponding to the changed speed is better than the spectrogram resolution corresponding to the speed before the change, storing the current rotating speed, changing the stepping control rotating mechanism according to the current speed to continuously change the speed, and carrying out the experiment again.
And if the spectrogram resolution corresponding to the changed speed is the same as that of the previous time, keeping the current speed change trend to control the rotating mechanism to continuously change the speed, and carrying out experiments again.
And if the spectrogram resolution corresponding to the changed speed and the spectrogram resolution corresponding to the speed before the change are reduced, returning to the previous rotating speed, controlling the rotating mechanism to continuously change the speed by the reverse speed change trend, and carrying out experiments again.
And if the spectrogram resolution is continuously increased along with the increase of the speed, and the spectrogram resolution is reduced after the speed is changed for a certain time, reducing the current speed change step, returning to the previous rotating speed, controlling the rotating mechanism to continuously change the speed, and carrying out the experiment again until the spectrogram resolution corresponding to the changed speed is inferior to the spectrogram resolution corresponding to the speed before the change, wherein the previous rotating speed is the rotating speed corresponding to the optimal spectrogram resolution.
The index parameters corresponding to the spectrogram resolution include one or more of spectrogram area, spectrogram peak height, spectrogram half-height width and rotating sideband peak height, usually because the rotating sideband peak is generated in the rotating process, and the spectrogram area of the rotating sideband peak is used as one of the index parameters for measuring the effect.
The sample tube automatic rotating device comprises a rotating mechanism and a speed regulating module, wherein the sample tube is arranged on the rotating mechanism, the rotating mechanism drives the sample tube to rotate, and the speed regulating module executes the method for automatically rotating the low-field small-sized nuclear magnetic resonance spectrometer to improve the spectrogram resolution, so that the rotating speed of the rotating mechanism is automatically regulated, and the spectrogram resolution under the optimal rotating speed is obtained.
The rotating mechanism comprises a motor and a synchronous transmission device, the motor drives a driving wheel of the synchronous transmission device to rotate, a driven wheel of the synchronous transmission device is driven to rotate, and a sample tube which is coaxial with the driven wheel rotates along with the driven wheel.
The one end and the drive belt of following the driving wheel are connected, wear to locate unable adjustment base from the other end of driving wheel in, and nonmagnetic from being provided with two nonmagnetic antifriction bearing support from the driving wheel rotation about between follow driving wheel and the unable adjustment base, prevent that the mechanical swing of sample cell outside the vertical axis that single bearing operation in-process caused from too big noise of introducing, unable adjustment base passes through the base buckle and sets up in nuclear magnetic resonance spectrometer's introduction port.
The motor is arranged on the side face of the nuclear magnetic resonance spectrometer through the nonmagnetic bracket, and plays a role in stable operation when the servo motor operates. The bracket comprises three vertical plates, the three vertical plates and the nuclear magnetic resonance spectrometer enclose a mounting cavity, and the motor is arranged in the mounting cavity; the vertical plate is provided with a through hole, and the motor controls the wiring of a wire.
The speed regulation module can manually set rotation parameters of the motor, such as rotation speed, acceleration and angle, through rotation speed control software, or starts an automatic adjustment rotating mechanism through a one-key automatic rotation speed adjustment control key, the rotation parameters obtained through calculation of the algorithm are used for configuring the rotation speed of the motor, and real-time state and parameter display is carried out through a display window.
The invention has the following beneficial effects:
the method for automatically rotating and improving the spectrogram resolution of the low-field small nuclear magnetic resonance spectrometer further improves the magnetic field uniformity of the low-field nuclear magnetic resonance spectrometer without changing the magnet and the shimming coil of the existing system, indirectly drives the sample tube to stably rotate by controlling the motor, extracts parameter data related to the resolution of the nuclear magnetic resonance spectrometer at different rotating speeds, compares and analyzes parameters related to the magnetic resonance experiment and the spectrogram resolution, iteratively calculates the corresponding rotating speed under the optimal experiment parameter to obtain the rotating speed with the best effect of overcoming the magnetic field nonuniformity, and then automatically adjusts the system to operate at the rotating speed in real time to obtain the optimal experiment effect to the utmost extent.
The method can automatically adjust the rotating speed of the sample tube in real time, eliminate the difference between the sample and the experimental parameters, and overcome the magnetic field nonuniformity vertical to the plane of the rotating shaft to a certain extent, thereby offsetting the magnetic field nonuniformity to a certain extent, improving the resolution of a nuclear magnetic resonance spectrogram, avoiding a large amount of test and comparison work of operators, and greatly improving the experimental efficiency.
Based on the method, the automatic rotating device for the sample tube of the low-field small nuclear magnetic resonance spectrometer, which is disclosed by the invention, can automatically rotate to improve the resolution of the spectrogram without changing the performance and the structure of the existing magnet and shimming coil, so that the sample tube of the low-field small nuclear magnetic resonance spectrometer can automatically rotate. The automatic rotating device for the sample tube is compact in size and easy to install, and the driven wheel and the bearing are made of non-magnetic materials to prevent magnetic field interference; the synchronous transmission structure is adopted, the synchronous transmission structure is suitable for transmission with a larger center distance between the sample tube and two shafts, has good flexibility and vibration resistance, ensures the rotating coaxiality of the sample tube in a magnetic field, and avoids the offset of the sample tube outside a vertical axis.
The sample tube automatic rotating device provided by the invention has strong adaptability, not only can be used for the existing magnetic resonance spectrometer, but also can be used after only a mechanical structure is slightly modified if other nuclear magnetic resonance equipment is replaced or a related system needing closed-loop rotation speed adjustment is adopted.
Drawings
FIG. 1 is a flow chart of a method according to the present invention;
FIG. 2 is a schematic diagram of the structure of the apparatus of the present invention;
FIG. 3 is a schematic view of the arrangement of sample tubes;
FIG. 4 is an assembled cross-sectional view of the driven wheel, stationary base and base clasp;
in the figure: the device comprises a motor 10, a driving wheel 11, a driven wheel 12, a groove 121, a fixing base 13, a rolling bearing 14, a base buckle 15, a screw hole 151, a transmission belt 16, a bracket 20, a vertical plate 21, a through hole 211, a nuclear magnetic resonance spectrometer 30, a radio frequency transceiver coil 31, a shim coil 32 and a sample tube 40.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
The invention provides a method for improving the spectrogram resolution by automatically rotating a low-field small-sized nuclear magnetic resonance spectrometer and an automatic sample tube rotating device for improving the spectrogram resolution by automatically rotating the low-field small-sized nuclear magnetic resonance spectrometer, aiming at solving the defects of complicated structure, inconvenient operation, low accuracy and the like of a small-sized permanent magnet nuclear magnetic resonance device in the prior art.
The method for automatically rotating and improving the spectrogram resolution of the low-field small nuclear magnetic resonance spectrometer 30 drives the sample tube 40 to rotate through the rotating mechanism; obtaining a corresponding spectrogram resolution index parameter based on a nuclear magnetic experiment result of the current rotating speed; controlling the rotating mechanism to change the speed to obtain a spectrogram resolution index parameter corresponding to the changed speed; and maintaining the control rotating mechanism to change the speed until the optimal spectrogram resolution is obtained, and controlling the rotating mechanism to drive the sample tube 40 to rotate at the rotating speed corresponding to the optimal spectrogram resolution.
In this embodiment, the parameter corresponding to the spectrogram resolution includes one or more of a spectrogram area, a spectrogram peak height, a spectrogram half-height width, and a rotation sideband peak height. The method comprises the steps of obtaining relevant parameters corresponding to the spectrogram resolution of the magnetic resonance experiment in real time, such as FID integral area and spectral line full width at half maximum, increasing the rotating speed according to the rotating speed step increment value, comparing the spectrogram parameters at different rotating speeds, keeping a better result, continuously iterating to finally obtain the rotating speed of the sample tube 40 corresponding to the optimal experimental spectrogram result, automatically adjusting the rotating speed of the system, obtaining higher spectrogram resolution and improving the experimental efficiency.
In theory, if the line width and the height of the spectrogram are narrowed and increased under the condition that other parameters are not changed, coupling and splitting of some samples become more obvious, and the current rotating speed overcomes the magnetic field nonuniformity of the nuclear magnetic resonance spectrometer 30 to a certain extent. And continuously adjusting the rotating speed, and comparing the result with the original spectral line to obtain the result with narrower line width and higher height after the rotating speed is increased, so that the higher the rotating speed is, the better the capability of overcoming the nonuniformity of the magnetic field is, and the higher the resolution of the spectrogram is. And vice versa. In order to find the rotating speed corresponding to the optimal spectrogram resolution more quickly, the strategy for controlling the changing speed of the rotating mechanism is as follows: and comparing the quality of spectrogram resolution of the nuclear magnetic experiments at different speeds before and after, and controlling the rotating mechanism to continuously change the speed according to the current speed change trend if the spectrogram resolution corresponding to the changed speed is superior to the spectrogram resolution corresponding to the speed before the change. And if the spectrogram resolution corresponding to the changed speed and the spectrogram resolution corresponding to the speed before the change are reduced, returning to the previous rotating speed, controlling the rotating mechanism to continuously change the speed by the reverse speed change trend, and carrying out experiments again.
In this embodiment, the experiment is performed by the nuclear magnetic resonance spectrometer 30 in the sample tube 40, the frequency domain signal data of the magnetic resonance experiment subjected to fourier transform is extracted, effective data is extracted at each set of rotation speed to perform mean value processing, and the area, half-height width, peak height and rotation side band peak of the spectrogram at different rotation speeds are compared, so that the rotation speed under the conditions of the maximum area of the spectrogram peak and the minimum area of the rotation side band peak is obtained, and the real-time result is fed back to perform real-time adjustment, so that the rotation speed when the experiment result is optimal (i.e., the spectrogram resolution is optimal).
And if the spectrogram resolution is continuously increased along with the increase of the speed, and the spectrogram resolution is reduced after the speed is changed for a certain time, reducing the current speed change step, returning to the previous rotating speed, controlling the rotating mechanism to continuously change the speed, and carrying out the experiment again until the spectrogram resolution corresponding to the changed speed is inferior to the spectrogram resolution corresponding to the speed before the change, wherein the previous rotating speed is the rotating speed corresponding to the optimal spectrogram resolution.
As shown in fig. 1, the flow of automatically adjusting the rotation speed of the rotation mechanism and obtaining the optimal spectrogram resolution according to the present invention is as follows:
1) after the rotating mechanism and the nmr spectrometer 30 are powered on and run stably, the hardware and control software of the rotating mechanism and the nmr spectrometer are initialized.
2) Setting experiment parameters of a magnetic resonance instrument, and setting an initial value v of the rotating speed of a rotating mechanism
0And appropriately addSpeed a
0And starting the rotating mechanism, and starting the 1 st magnetic resonance experiment after the sample tube 40 rotates stably.
3) Performing nuclear magnetic resonance experiment, performing Fourier transform on the acquired magnetic resonance signal by experiment software to obtain frequency domain data, and reading the frequency domain data P of a fixed point number by an automatic rotating speed regulating program
0Dat. The background noise of the signal is shielded through threshold processing, and the signal low noise can be effectively shielded by selecting a signal threshold, and a spectrogram effective area is reserved for data analysis. Subsequently, the height H of the spectral peak is determined
0The area S of the spectrogram is obtained by integral calculation
0And locating the peak height at 50% to obtain the half width W
0And sideband peak-to-peak height E due to rotation under non-uniform field
0And storing the parameter data.
4) Increasing the rotating speed according to the step △ n at equal intervals, continuing to perform the magnetic resonance experiment, judging whether two groups of data are measured, if not, returning to the step 2), measuring the spectrogram area S under the rotating speed
1Height of spectral peak H
1Full width at half maximum W of spectrogram
1Sideband peak height E
1Will rotate speed v
0And v
1The following four experimental parameter data were compared. And (3) judging whether the spectrogram resolution parameter is improved, if the spectrogram integral area is increased, the spectral peak is increased, the spectrogram half-height width is narrowed, and the sideband peak height is reduced, storing data with better parameters, and if the spectrogram resolution parameter is not improved, returning to the step 2). Then the rotating speed is changed again according to the steps, and the rotating speed v is adjusted
i-1And v
iAnd sequentially comparing and calculating the following four experimental parameter data.
5) And judging whether the iteration is always improved before the calculated parameters appear, and suddenly reducing the iteration at a certain rotating speed, which indicates that the rotating speed is increased to exceed the rotating speed value corresponding to the optimal resolution parameter. If the better parameter is not obtained before and is directly reduced, the parameter data is not saved and the step 2) is returned. If the iteration is always promoted before the parameters and is suddenly reduced at a certain rotating speed, the rotating speed stepping value takes a negative value, the stepping length is gradually reduced, and the step 2) is returned. According to the corresponding experimental data under multiple groups of rotating speeds, if the parameters are not increased or decreased any more, calculating to obtain the optimal experimental result pairCorresponding rotational speed v
BAnd ending the operation flow, otherwise, returning to the step 2) to carry out the next experiment until the condition is met.
Based on the method for automatically rotating and improving the spectrogram resolution, the invention also provides an automatic rotating device for the sample tube 40, which is used for automatically rotating and improving the spectrogram resolution of the low-field small-sized nuclear magnetic resonance spectrometer 30, as shown in fig. 2 and 3, the automatic rotating device comprises a rotating mechanism and a speed regulating module, wherein the sample tube 40 is arranged on the rotating mechanism, and the rotating mechanism drives the sample tube 40 to rotate. The sample tube 40 is perpendicularly fixed in the permanent magnet chamber of the NMR spectrometer 30 and the main magnetic field B
0The vertical orientation of the sample tube 40 in the appropriate position ensures that the sample is within the coverage area of the solenoid Radio Frequency (RF) transceiver coil 31, and the RF transceiver coil 31 and its tuned matching circuit are connected to the RF transceiver circuitry of the system. The arrays of shim coils 32 are respectively arranged at two poles of the magnet N, S, and the uniformity of magnetic fields in different directions in the magnet is adjusted through a shim circuit. The speed regulating module executes the method for improving the spectrogram resolution by automatically rotating the low-field small nuclear magnetic resonance spectrometer 30, automatically adjusts the rotating speed of the rotating mechanism, and obtains the optimal spectrogram resolution.
The rotating mechanism comprises a motor 10 and a synchronous transmission device, the motor 10 drives a driving wheel 11 of the synchronous transmission device to rotate, a driven wheel 12 of the synchronous transmission device is driven to rotate, and a sample tube 40 which is coaxial with the driven wheel 12 rotates along with the driven wheel 12. In this embodiment, the synchronous transmission device adopts a wheel train belt transmission structure, and the transmission ratio between the driving wheel 11 as the rotor of the motor 10 and the driven wheel 12 as the rotor of the sample tube 40 is 2: 1, the linear velocity of the driven wheel 12 is greater than that of the driving wheel 11, an "O" rubber ring is used as the transmission belt 16, the motor 10 drives the driving wheel 11 to rotate, and the driven wheel 12 is driven to rotate through the transmission belt 16, so that the sample tube 40 rotates. The transmission belt 16 is respectively fixed in the grooves 121 on the outer walls of the ends of the driving wheel 11 and the driven wheel 12, so that the transmission belt 16 is tightened and fixed to prevent slipping in the rotating process, the transmission belt 16 needs to be kept horizontal with the ground, and component force is prevented from being generated outside the transmission surface in the transmission process to prevent unstable operation.
The motor 10 is implemented as a servo motor and is controlled by servo motor control software, and the rotating speed, the acceleration and the angle of the servo motor can be accurately controlled by using upper computer software according to the requirements of users. The servo motor is connected with the servo motor motion controller and the power supply driving unit, the servo motor controller is controlled to enable the servo motor through upper computer software, the rotating speed and the acceleration of the servo motor are adjusted, the servo motor control software calls a driving function of the bottom layer motor 10 to realize conversion between set parameters and the pulse frequency of the motor 10 controller, the servo motor control software is responsible for enabling the motor 10, the driving motor 10 rotates at different rotating speeds, and the functions of setting the initial rotating speed, the acceleration and the angle and the rotating speed stepping initial value are achieved.
In this embodiment, the maximum rotation speed of the motor 10 is 4800r/min, and the transmission ratio of the driving wheel 11 to the driven wheel 12 is 2: 1, according to the theoretical formula, the rotation speed of the sample tube 40 must satisfy: ->The rotational speed can counteract the amount of magnetic field inhomogeneity within the sample volume. Under the condition of not considering the frictional resistance and the slippage of the transmission belt 16, according to the transmission ratio theory, the maximum rotating speed of the rotor of the sample tube 40 is 160Hz, namely 160 revolutions per second, and the maximum quantity of the magnetic field nonuniformity can be theoretically counteracted by 1.879 x 10
-6And T. However, even if the design is strict, friction and slip phenomena still exist in the rotating process, so that the actual effect is slightly lower than the theoretical value and is an allowable error.
As shown in fig. 4, one end of the driven wheel 12 is connected to the transmission belt 16, the other end of the driven wheel 12 is inserted into the fixed base 13, a nonmagnetic wear-resistant rolling bearing 14 (both the housing and the roller are made of nonmagnetic wear-resistant materials) is disposed between the nonmagnetic wear-resistant driven wheel 12 and the fixed base 13, and the fixed base 13 is disposed at the sample inlet of the nuclear magnetic resonance spectrometer 30 through the base buckle 15. In this embodiment, an upper rolling bearing 14 and a lower rolling bearing 14 are disposed between the driven wheel 12 and the fixed base 13, that is, one rolling bearing 14 is respectively embedded in the top and bottom slots of the fixed base 13, one end of the driven wheel 12 is inserted into the inner rings of the two rolling bearings 14, and is fixed by glue to prevent slipping. The driven wheel 12 is supported by the upper rolling bearing 14 and the lower rolling bearing 14 to rotate, the fixed base 13 is fixed with the nuclear magnetic resonance spectrometer 30 through the base buckle 15, the sample tube 40 is inserted into a proper position of the driven wheel 12, the driven wheel 12 drives the sample tube 40 to rotate stably, the friction coefficient in the rotating process is reduced, the rotating coaxiality of the sample tube 40 is guaranteed, the deviation of the sample tube 40 outside a vertical axis is avoided, and the stability in the operating process is improved. The base buckle 15 is fixed on the magnet case of the nmr spectrometer 30 by two plastic screws M3 # through a screw hole 151 transversely formed in the base buckle 15, and plays a role in stabilizing the rotation of the driven wheel 12. The materials of the driven wheel 12 and the rolling bearing 14 can be selected from polyoxymethylene, and the materials are tough and elastic and have good geometric stability and impact resistance.
For the fitting of the sample tube 40 to the driven wheel 12, the present invention provides two fitting structures. If different sizes of sample tubes 40 need to be inserted, driven wheels 12 with different inner diameter specifications can be used to match the sizes of the sample tubes 40. Or a driven wheel 12 with a fixed inner diameter is adopted, a soft plastic guide pipe matched with the outer diameter is inserted into the sample tube 40, and the outer diameter of the plastic guide pipe is matched with the inner diameter of the driven wheel 12, so that the sample tube 40 is fixed on the driven wheel 12. For example, the diameter of the sample inlet of the nmr spectrometer 30 is 10mm at most, and the inner cavity of the driven wheel 12 may be set to a fixed inner diameter of 10mm, 5mm, or 3mm, etc. according to the diameter of the sample tube 40. Or soft plastic catheters with the same outer diameter and different inner diameters are inserted into the driven wheel 12 with the inner cavity set to be 10mm, and then the sample tube 40 with the corresponding diameter is fixed.
The motor 10 is disposed on the side of the nmr spectrometer 30 through the nonmagnetic bracket 20, and the bracket 20 can be firmly locked on the side of the nmr spectrometer 30, so as to perform a stable operation function when the servo motor operates. The bracket 20 comprises three vertical plates 21, the three vertical plates 21 and the nuclear magnetic resonance spectrometer 30 enclose a mounting cavity, and the motor 10 is arranged in the mounting cavity; the vertical plate 21 is provided with a through hole 211, the motor 10 controls the wiring of the wire, and the normal operation of the nuclear magnetic system cannot be interfered in the operation process of the motor 10. In this embodiment, the nonmagnetic bracket 20 is formed by splicing acrylic plates, and the spliced bracket 20 is firmly bonded by glue.
The speed regulating module is provided with a one-key type automatic rotating speed regulating control key, can be implemented in a hardware or software mode according to implementation requirements, is used for starting the rotating speed of the automatic regulating rotating mechanism, and displays real-time states and parameters through the display window. Specifically, in this embodiment, the speed regulation module is internally provided with servo motor control software, and a one-key automatic rotating speed regulation control key and a rotating parameter real-time display window in a software form can be associated with an automatic rotating speed regulation algorithm, so as to obtain the rotating speed calculated by the algorithm in real time and transmit the rotating speed to the motor 10 to complete rotating speed conversion of the sample tube 40, and simultaneously display a plurality of rotating state parameters in real time, monitor the automatic rotating regulation process, and facilitate recording and comparison by a user. The servo motor control software can be conveniently embedded in nuclear magnetic experiment software, and has better portability.
In this embodiment, the mode of manually adjusting the rotation speed and the mode of automatically adjusting the rotation speed may be switched, and the mode may be implemented as a speed adjusting module implemented by rotation speed control software. In the manual rotation speed adjusting mode, the rotation parameters of the motor 10 can be manually set; in the automatic rotation speed adjusting mode, the method is correlated with an automatic rotation speed adjusting algorithm, and the rotation speed of the motor 10 is configured by the rotation parameters obtained through algorithm calculation.
The above examples are provided only for illustrating the present invention and are not intended to limit the present invention. Changes, modifications, etc. to the above-described embodiments are intended to fall within the scope of the claims of the present invention as long as they are in accordance with the technical spirit of the present invention.
Claims (7)
1. A method for automatically rotating and improving spectrogram resolution of a low-field small nuclear magnetic resonance spectrometer is characterized in that a rotating mechanism drives a sample tube to rotate; obtaining a corresponding spectrogram resolution index parameter based on a nuclear magnetic experiment result of the current rotating speed; controlling the rotating mechanism to change the speed to obtain a spectrogram resolution index parameter corresponding to the changed speed; maintaining the speed change of the rotating mechanism until the optimal spectrogram resolution is obtained, and controlling the rotating mechanism to drive the sample tube to rotate at the rotating speed corresponding to the optimal spectrogram resolution; the strategy for controlling the change speed of the rotating mechanism is as follows: comparing the quality of spectrogram resolution indexes of nuclear magnetic experiments at different speeds before and after, and controlling the rotating mechanism to continuously change the speed according to the current speed change trend if the spectrogram resolution corresponding to the changed speed is superior to the spectrogram resolution corresponding to the speed before the change; if the spectrogram resolution corresponding to the changed speed is the same as that of the previous time, the current speed change trend is kept to control the rotating mechanism to continuously change the speed; and if the spectrogram resolution corresponding to the changed speed is reduced compared with the previous speed, returning to the previous rotating speed, and controlling the rotating mechanism to continuously change the speed in a reverse current speed change trend.
2. The method for automatically rotating and improving the spectrogram resolution of a low-field small nuclear magnetic resonance spectrometer according to claim 1, wherein if the spectrogram resolution continuously increases with the increase of the speed and the spectrogram resolution decreases after a certain speed change, the current speed change step is reduced, the previous rotating speed is returned, the rotating mechanism is controlled to continuously change the speed until the spectrogram resolution corresponding to the changed speed is inferior to the spectrogram resolution corresponding to the speed before the change, and the previous rotating speed is the rotating speed corresponding to the optimal spectrogram resolution.
3. The method for automatically rotating and improving the spectrogram resolution of the low-field small nuclear magnetic resonance spectrometer according to claim 2, wherein the index parameters corresponding to the spectrogram resolution comprise one or more of spectrogram area, spectrogram peak height, spectrogram half-height width and rotation sideband peak height.
4. The sample tube automatic rotating device is characterized by comprising a rotating mechanism and a speed regulating module, wherein the sample tube is arranged on the rotating mechanism, the rotating mechanism drives the sample tube to rotate, the rotating mechanism comprises a motor and a synchronous transmission device, the motor drives a driving wheel of the synchronous transmission device to rotate, a driven wheel of the synchronous transmission device is driven to rotate, and the sample tube coaxially arranged with the driven wheel rotates along with the driven wheel; the speed regulating module executes the method for automatically rotating the low-field small nuclear magnetic resonance spectrometer to improve the spectrogram resolution as claimed in any one of claims 1 to 3, automatically adjusts the rotating speed of the rotating mechanism, and obtains the optimal spectrogram resolution.
5. The automatic sample tube rotating device for automatically rotating and improving the resolution of a spectrogram of a low-field small nuclear magnetic resonance spectrometer as claimed in claim 4, wherein one end of the driven wheel is connected with the transmission belt, the other end of the driven wheel is arranged in the fixed base in a penetrating manner, an upper non-magnetic rolling bearing and a lower non-magnetic rolling bearing are arranged between the non-magnetic driven wheel and the fixed base to support the driven wheel to rotate, and the fixed base is arranged at a sample inlet of the nuclear magnetic resonance spectrometer through a base buckle.
6. The automatic sample tube rotating device for automatically rotating and improving the resolution of a spectrogram of a low-field small-sized nuclear magnetic resonance spectrometer as claimed in claim 4, wherein the motor is arranged on the side surface of the nuclear magnetic resonance spectrometer through a nonmagnetic bracket, the bracket comprises three vertical plates, the three vertical plates and the nuclear magnetic resonance spectrometer enclose a mounting cavity, and the motor is arranged in the mounting cavity; the vertical plate is provided with a through hole, and the motor controls the wiring of a wire.
7. The automatic rotating device for the sample tube for automatically rotating and improving the spectrogram resolution of the low-field small-sized nuclear magnetic resonance spectrometer as claimed in claim 4, wherein the speed regulating module is provided with a one-key automatic rotating speed regulating control key for starting the automatic rotating speed regulating mechanism and displaying the real-time state and parameters through the display window.
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