A method for extracting pressure of a porous traditional Chinese medicine tablet based on terahertz time-domain difference characteristics

Abstract

This invention provides a method for extracting the pressure of porous traditional Chinese medicine (TCM) tablets based on terahertz time-domain difference characteristics. A pressure detection model is constructed based on the Heckel equation and effective medium theory. The nominal porosity of the TCM tablets under different pressures is obtained through mechanical and morphological parameters. Utilizing the differences in terahertz time-domain spectral characteristic parameters of the TCM tablets under different pressures, the intrinsic refractive index of the porous TCM powder is extracted. These parameters are then applied to the pressure detection model to achieve non-contact, rapid, and non-destructive measurement of the TCM tablet pressure.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, specifically to a method for extracting the pressure of pore-forming Chinese medicine tablets based on terahertz time-domain difference characteristics. Background Technology

[0002] Traditional Chinese medicine (TCM) tablets constitute the largest proportion of solid TCM dosage forms and are one of the most widely used dosage forms. They offer advantages such as stable quality, accurate dosage, and ease of administration. The mechanical properties of TCM tablets refer to their properties under certain loads and are crucial parameters in tablet production and development. Different pressures are used in the production of different TCM tablets, resulting in varying mechanical properties. This directly affects the mechanical properties of the tablets, and consequently, the efficacy of the drug. However, there is currently little research on pressure testing of TCM tablets, and obtaining the tableting pressure for solid tablets with unknown pressures presents a significant challenge.

[0003] Terahertz radiation, characterized by low energy, a wide spectrum, and strong penetration, does not cause ionization damage to matter. It provides information on open and closed pores and, due to its faster and safer characteristics, has become a highly competitive emerging non-destructive testing technology in recent years. Terahertz spectroscopy possesses extremely high resolution, reflecting not only the internal motion of molecules but also intermolecular interactions. Furthermore, by utilizing the coherence of terahertz pulses, subtle changes in different components and structures within samples can be detected, and isomers of various sample molecules can be distinguished. It has significant scientific and practical value for studying the pressure of traditional Chinese medicine tablets. Summary of the Invention

[0004] In view of this, the present invention provides a method for extracting the pressure of porous traditional Chinese medicine tablets based on terahertz time-domain difference characteristics. A pressure detection model is constructed based on the Heckel equation and effective medium theory. The nominal porosity of the tablets under different pressures is obtained through relevant parameters such as mechanical and morphological characteristics. Utilizing the differences in terahertz time-domain spectral characteristic parameters of the traditional Chinese medicine tablets under different pressures, the intrinsic refractive index of the porous traditional Chinese medicine powder is extracted. These parameters are then applied to the pressure detection model to achieve the detection of the pressure of the traditional Chinese medicine tablets, achieving non-contact, rapid, and non-destructive measurement.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A method for extracting the pressure of pore-forming traditional Chinese medicine tablets based on terahertz time-domain difference features, the method comprising:

[0007] Step 1: Construct a pressure detection model based on Heckel's equations and effective medium theory;

[0008] Step 2: Prepare multiple solid tablets of the same Chinese medicine powder under different pressures, and measure the relevant parameters of the Chinese medicine tablets.

[0009] Step 3: Obtain the porosity f of the tablet under different pressures using the formula, and determine the constant values ​​k, A in the pressure detection model;

[0010] Step 4: Use a terahertz time-domain spectroscopy system to test the spectral time-domain signal of the Chinese medicine tablets and calculate the terahertz time-domain difference characteristic parameters of different tablets; use the terahertz time-domain difference characteristic parameters to calculate the effective refractive index n of the tablets under different pressures.

[0011] Step 5: Perform a linear fit between the porosity and the effective refractive index of the tablets under different pressures based on the least squares principle, and extrapolate to obtain the intrinsic refractive index n of the traditional Chinese medicine powder. s ;

[0012] Step 6: Combine the constant values ​​k and A obtained in Step 3 with the intrinsic refractive index n obtained in Step 5. s The sample value is used as a fixed value in the pressure detection model. The effective refractive index n of the sample with unknown pressure is measured in step 4 and applied to the pressure detection model to obtain the pressure value P of the tablet.

[0013] Further: In step 1, a pressure detection model is constructed based on the Heckel equation and the effective medium theory.

[0014]

[0015] Where n is the effective refractive index of the sample, n s Let be the intrinsic refractive index of the sample, and k and A be constants.

[0016] Further: In step 2, the same type of Chinese herbal powder is prepared into multiple solid tablets under different pressures. The mass of the tablets is measured using an electronic balance, and the thickness and diameter of the tablets are measured using vernier calipers. The relative density D of the tablets under different pressures is calculated.

[0017]

[0018] Where W is the sample mass, d is the sample diameter, h is the sample thickness, and ρ true This represents the true density of the sample.

[0019] Further: In step 3, the porosity f of the tablet under different pressures is obtained by formula;

[0020] f = 1 - D

[0021] Using the Heckel equation, the relationship between different pressures and relative density is obtained:

[0022] ln[1 / (1-D)]=k×P+A

[0023] Plot ln[1 / (1-D)] and P, and obtain the values ​​of k and A through linear fitting.

[0024] Further: In step 4, firstly, the time-domain waveform of the terahertz wave passing directly through dry air in a sample-free state is obtained as a reference. Then, the traditional Chinese medicine tablet is placed in the sample cell, and the time-domain waveform of the terahertz wave passing through the sample is obtained to obtain the time-domain difference characteristics of the sample relative to the air reference. Multiple measurements are taken at different positions for each sample, and the average value is calculated. The effective refractive index n of the sample is then calculated using the obtained delay time.

[0025] (nn air )×d=Δt×c

[0026] Where, n air The refractive index of air is typically set to n. air =1, Δt is the delay time of the sample relative to the air reference, and c is the speed of light in a vacuum.

[0027] Further, in step 5, a linear relationship is established between the effective refractive index and porosity of the samples under different pressures. A linear fit is performed using the least squares method, with porosity *f* as the x-coordinate and the effective refractive index *n* of the tablet under different pressures as the y-coordinate, resulting in a linear relationship graph. Specifically, extrapolation calculations from the linear relationship graph show that when the porosity is 0, the corresponding y-coordinate value in the graph is the intrinsic refractive index *n* of the sample. s .

[0028] Furthermore: In step 6, the constant value k,A obtained in step 3 and the intrinsic refractive index n obtained in step 5 are combined. s The sample value is used as a fixed value in the pressure detection model. The effective refractive index n of the sample with unknown pressure is measured in step 4 and applied to the pressure detection model to obtain the pressure value P of the tablet.

[0029] The beneficial effects of this invention are as follows:

[0030] This invention provides a method for extracting the pressure of pore-forming traditional Chinese medicine tablets based on terahertz time-domain difference characteristics, which reduces damage to the traditional Chinese medicine samples, increases the utilization rate of the samples, and provides a new approach for the detection of pressure in traditional Chinese medicine tablets. Attached Figure Description

[0031] Figure 1 This is a flowchart of a method for extracting the pressure of pore-forming Chinese medicine tablets based on terahertz time-domain difference features.

[0032] Figure 2 This is for determining the constants in the pressure detection model.

[0033] Figure 3 To create the terahertz time-domain waveform of the experimental sample.

[0034] Figure 4 This represents the relationship between porosity and effective refractive index. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Other embodiments obtained by those skilled in the art based on the embodiments of this invention without conducting groundbreaking research are all within the scope of protection of this invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0036] The specific operation steps of this invention are as follows:

[0037] (1) Constructing a pressure detection model: Based on the Heckel equation and the effective medium theory, a pressure detection model is constructed;

[0038]

[0039] Where n is the effective refractive index of the sample, n s Let be the intrinsic refractive index of the sample, and k and A be constants.

[0040] (2) Sample preparation and relative density calculation: The traditional Chinese medicine powder after pore-forming treatment was prepared into cylindrical solid tablets using a tablet press. The sample pressure was changed during the tablet preparation process to obtain six traditional Chinese medicine tablet samples under different pressures.

[0041] The prepared traditional Chinese medicine solid tablets under different pressures were made from the same batch of raw materials as the test samples. Except for the pressure during tableting, the samples were identical, and there were no other artificial or natural defects. Cylindrical solid tablets were obtained using a tablet press. By changing the sample pressure during tableting, six different types of traditional Chinese medicine tablets under different pressures were obtained.

[0042] The mass of the tablets was measured using an electronic balance, and the thickness and diameter of the tablets were measured using vernier calipers. The relative density D of the traditional Chinese medicine tablets under different pressures was calculated using a formula.

[0043]

[0044] Where W is the sample mass, d is the sample diameter, h is the sample thickness, and ρ true This represents the true density of the sample.

[0045] (3) Determination of porosity and constants k and A:

[0046] Using the relationship between relative density and porosity, we can obtain:

[0047] f = 1 - D

[0048] Using the Heckel equation, the relationship between different pressures and relative density is obtained:

[0049] ln[1 / (1-D)]=k×P+A

[0050] Where P is pressure, D is the relative density at pressure P, and k and A are constants. Plotting ln[1 / (1-D)] against P, the values ​​of k and A are obtained through linear fitting, where k is the slope and A is the value of ln[1 / (1-D)] when P is 0. The fitting results are as follows: Figure 2 As shown.

[0051] (4) Terahertz time-domain spectroscopy system detection and effective refractive index calculation of the sample: In order to avoid the influence of water vapor on the experiment, the terahertz time-domain spectroscopy system was operated in transmission mode. During the experiment, the sample chamber was filled with dry air, the air humidity was controlled below 3%, and the temperature was controlled at around 20℃.

[0052] First, the terahertz transmission time-domain waveform of an empty sample holder was acquired, i.e., the waveform of the terahertz wave passing through dry air was used as a reference. Then, the traditional Chinese medicine tablets were placed in the sample cell, and the time-domain waveform of the terahertz wave passing through the sample was obtained. To ensure the accuracy of the test, the time-domain waveforms of the reference and sample were measured 10 times, and the average value was taken as the final test value, as shown in the attached figure. Figure 3 As shown, where F 1～6 These represent six different types of pressure.

[0053] In the time-domain spectrum, the effective refractive index n of the sample is calculated using the time delay of the sample relative to an air reference.

[0054] (nn air )×h=Δt×c

[0055] Where, n air The refractive index of air is typically set to n. air =1, Δt is the delay time of the sample relative to the air reference, c is the speed of light in vacuum, and h is the sample thickness.

[0056] (5) Calculation of intrinsic refractive index:

[0057] The nominal porosity f nominalUsing the x-coordinate as the x-coordinate and the effective refractive index n of the sample under different pressures as the y-coordinate, a linear fit based on the least squares principle is performed to obtain the formula y = ax + b. Setting x = 0, we get y = b, which means that when the nominal porosity = 0, the intrinsic refractive index of the sample is extrapolated to obtain the ordinate of point A. Figure 4 As shown.

[0058] (6) Pressure testing:

[0059] Combine the constant values ​​k and A obtained in step 3 with the intrinsic refractive index n obtained in step 5. s The sample value is used as a fixed value in the pressure detection model. The effective refractive index n of the sample with unknown pressure is measured in step 4 and applied to the pressure detection model to obtain the pressure value P of the Chinese medicine tablet with unknown pressure.

[0060] In this invention, multiple experiments were conducted, and the experimental data showed a high degree of overlap, ensuring the accuracy of the experiments. The above description is merely a preferred embodiment of the present invention and is not limited to it. Those skilled in the art can select other terahertz refractive index-porosity models. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for extracting the pressure of pore-forming traditional Chinese medicine tablets based on terahertz time-domain difference features, characterized in that, The method includes: Step 1: Construct a pressure detection model based on Heckel's equations and effective medium theory; Step 2: Prepare multiple solid tablets of the same Chinese herbal powder under different pressures, measure the relevant parameters of the tablets, and calculate the relative density D of the tablets under different pressures; Step 3: Obtain the porosity f of the tablet under different pressures using the formula, and determine the constant values ​​k, A in the pressure detection model; Step 4: Use a terahertz time-domain spectroscopy system to test the spectral time-domain signal of the Chinese medicine tablets and calculate the terahertz time-domain difference characteristic parameters of different tablets; use the terahertz time-domain difference characteristic parameters to calculate the effective refractive index n of the tablets under different pressures. Step 5: Perform a linear fit between the porosity and the effective refractive index of the tablets under different pressures based on the least squares principle, and extrapolate to obtain the intrinsic refractive index n of the traditional Chinese medicine powder. s ; Step 6: Combine the constant values ​​k and A obtained in Step 3 with the intrinsic refractive index n obtained in Step 5. s The sample value is used as a fixed value in the pressure detection model. The effective refractive index n of the sample with unknown pressure is measured in step 4 and applied to the pressure detection model to obtain the pressure value P of the tablet. In step 1, a pressure detection model is constructed based on the Heckel equation and the effective medium theory: Where n is the effective refractive index of the sample, n s Let be the intrinsic refractive index of the sample, and k and A be constants. Using the Heckel equation, the relationship between different pressures and relative density is obtained: ln[1 / (1-D)]=K×P+A Where P is the pressure, D is the relative density at pressure P, and k and A are constants; plot ln[1 / (1-D)] against P, and obtain the values ​​of k and A through linear fitting, where k is the slope and A is the value of ln[1 / (1-D)] when P is 0; In the time-domain spectrum, the effective refractive index of the sample is calculated using the lag time of the sample relative to an air reference: (n-n air )×h=Δt×c Where, n air The refractive index of air is typically set to n. air =1, Δt is the delay time of the sample relative to the air reference, c is the speed of light in vacuum, and h is the sample thickness.

2. The method for extracting the pressure of pore-forming traditional Chinese medicine tablets based on terahertz time-domain difference features according to claim 1, characterized in that: In step 2, the same type of traditional Chinese medicine powder is prepared into multiple solid tablets under different pressures. Relevant parameters of the tablets are measured, and the relative density D of the tablets under different pressures is calculated. Where W is the sample mass, d is the sample diameter, h is the sample thickness, and ρ true This represents the true density of the sample.

3. The method for extracting the pressure of pore-forming traditional Chinese medicine tablets based on terahertz time-domain difference features according to claim 1, characterized in that: In step 3, the porosity f of the tablet under different pressures is obtained by formula, and the constant value k,A in the pressure detection model is determined. f = 1 - D Using the Heckel equation, the relationship between different pressures and relative density is obtained: ln[1 / (1-D)]=k×P+A Plot ln[1 / (1-D)] and P, and obtain the values ​​of k and A through linear fitting.

4. The method for extracting the pressure of pore-forming traditional Chinese medicine tablets based on terahertz time-domain difference features according to claim 1, characterized in that: In step 4, the time-domain waveform of the terahertz wave passing directly through dry air in a sample-free state is first obtained as a reference. Then, the traditional Chinese medicine tablets are placed in the sample cell, and the time-domain waveform of the terahertz wave passing through the sample is obtained to obtain the time-domain difference characteristics of the sample relative to the air reference. Multiple measurements are taken at different positions of each sample, and the average value is taken. The effective refractive index n of the sample is calculated from the obtained delay time. (n-n air )×d=Δt×c Where, n air The refractive index of air is typically set to n. air =1, Δt is the delay time of the sample relative to the air reference, and c is the speed of light in a vacuum.

5. The method for extracting the pressure of pore-forming traditional Chinese medicine tablets based on terahertz time-domain difference features according to claim 1, characterized in that: In step 5, a linear relationship is established between the effective refractive index and porosity of the samples under different pressures. A linear fit is performed using the least squares method, with porosity *f* as the x-axis and the effective refractive index *n* of the tablet under different pressures as the y-axis, resulting in a linear relationship graph. When the porosity is 0, the corresponding y-axis value in the graph is the intrinsic refractive index *n* of the sample. s .

6. The method for extracting the pressure of pore-forming traditional Chinese medicine tablets based on terahertz time-domain difference features according to claim 1, characterized in that: In step 6, the constant values ​​k and A obtained in step 3 and the intrinsic refractive index n obtained in step 5 are combined. s The sample value is used as a fixed value in the pressure detection model. The effective refractive index n of the sample with unknown pressure is measured in step 4 and applied to the pressure detection model to obtain the pressure value P of the tablet.

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