CN111879805A - A kind of plant pattern identification method for effective gold plating by scanning electron microscope - Google Patents

Abstract

The invention discloses a method for identifying a plant texture effectively plated with gold by a scanning electron microscope, which aims at the characteristic of scanning the plant tiny plant texture of the electron microscope by forensic physical evidence, establishes the structure of the plant remnant plant texture of the scanning electron microscope, eliminates the conglomerated blocking object existing in the plant texture cell structure after protoplast is dried, and leads the plant texture cell structure to become clear five impurities; the invention increases the identification accuracy of the plant texture of the material to be examined, and improves the identification effect of the forensic on the scanning electron microscope plant small remnant.

Description

A kind of plant pattern identification method for effective gold plating by scanning electron microscope

technical field

_The invention discloses a plant grain identification method for effective gold plating by scanning electron microscope, and relates to a plant grain identification method of scanning electron microscope. At a vertical angle of 90 °C on the upper part of the wood, a knife cut off the blockages in the vegetative cell structure that coalesced after the protoplasts were dried; the vegetative cell structure became clear, without any blockages, and the structure was smooth. The invention thus realizes a new method for identification of plant patterns by scanning electron microscope, and belongs to the technical field of forensic material evidence identification.

technical background

In the field of forensic forensics, scanning electron microscopes are mainly used to observe the three-dimensional structure of the samples submitted for inspection. The three-dimensional structure of scanning electron microscopy greatly enriches and complements the insufficiency of the two-dimensional transmission structure of optical microscopy. Because the sample contains a lot of water, when observed with a scanning electron microscope, the surface structure of the sample is easily damaged under the action of vacuum and electron beams, which affects the structural integrity of the plant texture. Therefore, the planted samples must be processed by a series of chemical and physical methods before using the scanning electron microscope for experimental observation.

The observation surface of the plant pattern sample is cut out, and the test material (usually the cross section of the plant stem and leaf) is cut from the plant pattern organism. The surface was observed with a scanning electron microscope. According to the research purpose of the test, different test materials are selected and cut. The properties of different organs and tissues of plants are different, and the observed parts are also different. Scanning electron microscope scanning can cut out materials of different thicknesses according to the experimenter's test intention; rotate the sample table at different angles according to the test material test, so that the three-dimensional structure of the observed material can be displayed; the scanning electron microscope plant pattern identifies the drying method of the sample, The water-containing plant texture sample evaporates under vacuum or normal temperature and pressure. When the water molecules are completely detached from the sample surface, there is a surface tension between the sample surface and the water, which can easily destroy the surface structure of the sample. In the process of plant pattern identification of plant specimens studied by scanning electron microscopy of plant patterns, blockages that coalesced from plant cells after drying by protoplasts were often encountered, which directly affected the observation of cell structures and submicroscopic photography. As a result, it is impossible to carry out any film processing for plant pattern identification, let alone sub-microscopic photography forensics, which severely limits the process of plant pattern identification and solving cases.

SUMMARY OF THE INVENTION

The invention discloses an effective gold-plated plant pattern identification method by a scanning electron microscope. The trace material evidence of plant debris is used to find clues for criminal investigators to solve cases, narrow the scope of detection, provide criminal evidence, and provide criminal investigators with scanning electron microscopes. scientific basis.

The invention provides a scanning electron microscope effective gold-plated plant pattern identification method, comprising the following steps:

1) Put 2 pieces of plant debris to be tested, soak them in clean water for 2-4 hours respectively;

2) Take out the plant debris, put it in FAA fixative solution, and fix it for 48 hours;

3) Dehydrate the plants in step 2), namely: use 65%, 765%, 85%, 95%, ethanol water of different concentrations, and each gradient interval is 2 hours;

4) Put the plant in step 3) into 100% dehydration for 1 hour, then take it out and put it into acetone to continue dehydration for 30 minutes;

5) Apply the CO ₂ critical point drying method to perform critical point drying on the plants in step 4);

6) Using a double-sided blade, for the plants in step 5), cut the double-sided blade at the 90 °C angle perpendicular to the upper part of the test material, and cut off the blockage of protoplasts that coalesce after drying in the vegetative cell structure. thing;

7) The plant debris in step 6) is made into the identification material of the scanning electron microscope plant pattern;

8) Put the plant debris in step 7), stick it on the sample stage, and use IB-3 ion sputtering to coat the gold film with a thickness of 200Å.,

9) Observing and photographing the gold-plated material in step 8) using a Nissan S-570 scanning electron microscope with a voltage of 20kV.

The observation surface of the plant pattern sample is cut out, and the test material (usually the cross section of the plant stem and leaf) is cut from the plant pattern organism. The surface was observed with a scanning electron microscope. According to the research purpose of the test, different test materials are selected and cut. The properties of different organs and tissues of plants are different, and the observed parts are also different. Scanning electron microscope scanning can cut out materials of different thicknesses according to the experimenter's test intention; the test material test needs to rotate the sample table at different angles, so that the three-dimensional structure of the observed material can be displayed; the scanning electron microscope plant pattern identifies the drying method of the sample

The water-containing plant texture sample evaporates under vacuum or normal temperature and pressure. When the water molecules are completely detached from the sample surface, there is a surface tension between the sample surface and the water, which can easily destroy the surface structure of the sample. Therefore, the sample needs to use a special method to eliminate the surface tension generated before observation, remove the moisture inside the sample, and keep the surface structure of the sample intact.

Critical point drying method: Using the characteristic of CO ₂ that does not generate surface tension in the critical point drying state, the liquid in the plant pattern sample is vaporized, so as to ensure that the plant pattern sample can be completely dried. This drying method avoids the effect of surface tension on the plant pattern. Therefore, the original ultrastructure of the plant pattern material will not be changed.

Preparation of the test material on the inner surface of the cuticle of the planted striae. After the cuticle was dehydrated and dried with different gradients of ethanol, it was adhered to the sample stage, and the gold film was sputtered with IB-3 ions, with a thickness of 200Å. The gold-plated material used Nissan S -570 scanning electron microscope observation and photography, the voltage is 20kV.

In the process of plant pattern identification of plant specimens studied by plant pattern scanning electron microscope, a series of biochemical reagents such as osmic acid fixative, ethanol dehydration with different concentrations, xylene transparency, and acetone co ₂ critical point drying were used, and the gold plating was directly applied. Film inspection material. In the field of scanning electron microscopy, the blockages of plant cells coalescing after being dried by protoplasts are often encountered, which directly affects the observation and submicroscopic photography of cell structures. As a result, it is impossible to carry out any film processing for plant pattern identification, let alone sub-microscopic photography forensics, which severely limits the process of plant pattern identification and solving cases. Therefore, it is necessary to reform the scanning electron microscope plant pattern identification and sample preparation technology, carry out the original traceable plant pattern identification research on the specimen, and understand and master the basic scientific connotation of plant pattern.

Using a double-sided blade at a 90 °C angle perpendicular to the upper part of the sample, a knife was used to cut off the blockages in the plant print cell structure where the protoplasts coalesced after drying, and a clear surface of the plant print (Plant Print) was obtained. The visual texture highlights the very real structure of the plant material, eliminates the blockages in the plant stripe cell structure that coalesce after protoplast drying, and makes the plant stripe cell structure a clear, smooth structure without any blockages; A new method for the identification of plant grains by scanning electron microscopy.

The positive effect of the present invention is:

Aiming at the characteristics of microscopic plant patterns of forensic material scanning electron microscopy, the structure of plant debris planting patterns of scanning electron microscope was established, and the blockage of protoplasts that coalesced after drying was eliminated in the plant pattern cell structure, so that the plant pattern cell structure became clear and mixed. In the process of scanning electron microscope plant debris sample processing, the section of the plant texture sample material after CO ₂ critical point drying was cut with a double-sided blade, at a 90 °C angle perpendicular to the upper part of the sample material. With one knife, the blockages that coalesced after the protoplasts were dried in the plant pattern cell structure were cut off, so that the plant pattern cell structure became a clear, smooth structure without any blockages, which increased the accuracy of plant pattern identification of the specimen. The identification effect of the scanning electron microscope on the microscopic plant debris of the forensic medicine is improved, and the invention produces the scanning electron microscope plant debris plant pattern identification standard sample, which provides a theoretical basis for accurate case solving, and provides the scanning electron microscope plant debris plant pattern for criminal investigation and solving. Technical support for structure identification.

Description of drawings

Fig. 1 is the conventional scanning electron microscope inspection material picture of embodiment 1;

2 is a picture of the scanning electron microscope inspection material prepared by the method of the present invention in Example 1;

Fig. 3 is embodiment 1 plant pattern identification specimen control sample picture;

Fig. 4 is the conventional scanning electron microscope inspection material picture of embodiment 2;

5 is a picture of the scanning electron microscope inspection material prepared by the method of the present invention in Example 2;

Figure 6 is a picture of a control sample of the plant pattern identification specimen in Example 2.

Fig. 7 is the conventional scanning electron microscope inspection material picture of embodiment 3;

8 is a picture of the scanning electron microscope inspection material prepared by the method of the present invention in Example 3;

FIG. 9 is a picture of a control sample of the plant pattern identification specimen in Example 3. FIG.

Detailed ways

The present invention is further described by the following examples, and does not limit the present invention in any way. On the premise of not departing from the technical solutions of the present invention, any changes or changes that are easily realized by those of ordinary skill in the art made by the present invention will be fall within the scope of the claims of the present invention.

Example 1

See Figure 1 for a scanning electron microscope (SEM) material (ruler = 200 μm) of tiny plant fragments on the clothes of a corpse. The structure is unclear after ion sputtering gold plating;

1) Put 2 pieces of plant debris on the clothes of the corpse, soak them in clean water for 2-4 hours respectively;

2) Take out the plant debris, put it in FAA fixative solution, and fix it for 48 hours;

3) Dehydrate the plants in step 2), namely: use 65%, 765%, 85%, 95% ethanol water with different concentrations, and each gradient interval is 2 hours;

4) Put the plant in step 3) into 100% dehydration for 1 hour, then take it out and put it into acetone to continue dehydration for 30 minutes;

5) Apply the CO ₂ critical point drying method to perform critical point drying on the plants in step 4);

6) Using a double-sided blade, for the plants in step 5), cut the double-sided blade at the 90 °C angle perpendicular to the upper part of the test material, and cut off the blockage of protoplasts that coalesce after drying in the vegetative cell structure. thing;

7) The plant debris in step 6) is made into the identification material of the scanning electron microscope plant pattern;

8) Stick the plant debris in step 7) on the sample stage, and use IB-3 ion sputtering to coat the gold film with a thickness of 200Å;

9) Observing and photographing the gold-plated material in step 8) using a scanning electron microscope with a voltage of 20kV. The scanning electron microscope examines the material as shown in Figure 2 (scale = 115 μm), and the structure is very clear.

As shown in Figure 3, by comparing the plant pattern identification map, it is clear that the samples all belong to the same crime scene.

Conclusion: The vegetative pattern identification by scanning electron microscope from the outside to the inside clarifies that the anatomical structure of the plant pattern epidermis is the cell trace of the stem of the dicotyledonous plant, the plant pattern of the standard sample and the plant at the crime scene, the corpse coat and the trousers adhering plant. Therefore, the plants at the crime scene, and the plant fragments adhered to the corpse’s coat and trousers are the same plant as the standard for the identification of the plant pattern of the specimen, namely: soybean ( Glycine.max L) plant leaves. Soybean is plant phylum Angiospermae, Dicotyledoneae, Leguminosae, Papilionoideae, Trib. Phaseoleae, Soybean Subtrib. Glycininae Glycine Willd. plants. By comparing the identification maps of soybean plant patterns, it is clarified that the plant patterns identification maps of the samples belong to the same crime scene.

Example 2

Figure 4 shows the tiny fragments of plants adhering to the coat of a corpse. Scanning electron microscope experiment (ruler = 100 μm), after the gold film was plated, the internal structure could not be clearly seen;

Utilize a kind of scanning electron microscope plant pattern identification method provided by the invention, comprising the following steps:

1) 2 pieces of plant debris adhered to the coat of the corpse were soaked in clean water for 2-4 hours respectively;

2) Take out the plant debris, put it in FAA fixative solution, and fix it for 48 hours;

3) Dehydrate the plants in step 2), namely: use 65%, 765%, 85%, 95%, ethanol water of different concentrations, and each gradient interval is 2 hours;

4) Put the plant in step 3) into 100% dehydration for 1 hour, then take it out and put it into acetone to continue dehydration for 30 minutes;

5) Apply the CO ₂ critical point drying method to perform critical point drying on the plants in step 4);

6) Using a double-sided blade, for the plants in step 5), cut the double-sided blade at the 90 °C angle perpendicular to the upper part of the test material, and cut off the blockage of protoplasts that coalesce after drying in the vegetative cell structure. thing;

7) The plant debris in step 6) is made into the identification material of the scanning electron microscope plant pattern;

8) Put the plant debris in step 7), stick it on the sample stage, and use IB-3 ion sputtering to coat the gold film with a thickness of 200Å.,

9) Observing and photographing the gold-plated material in step 8) with a Nissan S-570 scanning electron microscope with a voltage of 20kV, see Figure 5 for scanning electron microscope inspection (ruler=120μm), the structure is very clear;

As shown in Figure 6, through the scanning electron microscope identification of the plant pattern from the surface to the inside, it is clarified that the anatomical structure of the plant pattern epidermis is the cell trace of the stem of the dicotyledonous plant, and the standard sample is adhered to the plants at the crime scene, the corpse coat and pants The structure of the plant pattern of the plant is exactly the same. Therefore, the plant at the crime scene, the plant debris attached to the corpse's coat and trousers are the same plant as the standard for the identification of the plant pattern of the specimen, namely: the anther of Medicago sativa L. . Alfalfa is the phylum Angiospermae, Dicotyledon, Leguminosae, Alfalfa Medicago, Alfalfa group Sect. plants. By comparing the identification maps of soybean plant patterns, it is clarified that the plant patterns identification maps of the samples belong to the same crime scene.

Example 3

Refer to Fig. 7 for the scanning electron microscope examination of tiny plant fragments on the clothes of a corpse in a certain case (ruler = 120 μm). After ion sputtering gold plating, the structure is unclear;

A scanning electron microscope plant pattern identification method provided by the invention comprises the following steps:

1) Put 2 pieces of plant debris on the clothes of the corpse, soak them in clean water for 2-4 hours respectively;

2) Take out the plant debris, put it in FAA fixative solution, and fix it for 48 hours;

3) Dehydrate the plants in step 2), namely: use 65%, 765%, 85%, 95%, ethanol water of different concentrations, and each gradient interval is 2 hours;

4) Put the plant in step 3) into 100% dehydration for 1 hour, then take it out and put it into acetone to continue dehydration for 30 minutes;

5) Apply the CO ₂ critical point drying method to perform critical point drying on the plants in step 4);

6) Using a double-sided blade, for the plants in step 5), cut the double-sided blade at the 90 °C angle perpendicular to the upper part of the test material, and cut off the blockage of protoplasts that coalesce after drying in the vegetative cell structure. thing;

7) The plant debris in step 6) is made into the identification material of the scanning electron microscope plant pattern;

8) Put the plant debris in step 7), stick it on the sample stage, and use IB-3 ion sputtering to coat the gold film with a thickness of 200Å.,

9) Observing and photographing the gold-plated material in step 8) using a Nissan S-570 scanning electron microscope with a voltage of 20kV, see Figure 8 for the tiny plant fragments on the clothes of the corpse; After a knife, ion sputtering gold plating, the effect: the structure is very clear.

As shown in Figure 9, the identification of the plant pattern by scanning electron microscope clarifies that the anatomical structure of the plant pattern epidermis is the cell trace of the stem of the dicotyledonous plant. The structure is completely consistent. Therefore, the plants at the crime scene and the plant fragments adhered to the corpse's coat and pants are the same plant as the identification standard of the plant pattern of the specimen, namely: Caltha palustris L. stem (structure). It is angiosperm phylum Angiospermae, Dicotyledoneae, Archichlamydeae, Ranunculaceae, Ranunculaceae, Subfam. Helleboroidae, Trib.Trollieae, Caltha L. plants.

By comparing the plant pattern identification maps, it is clarified that the plant pattern identification maps of the specimens belong to the same crime scene. By comparing the plant pattern identification map, it is clear that the samples all belong to the same crime scene.

Claims (3)

1. A method for identifying the texture of effective gold plating of a scanning electron microscope comprises the following steps:

1) respectively putting 2 pieces of plant debris to be detected into clear water for soaking and cleaning for 2-4 hours;

2) taking out the plant debris, putting the plant debris into FAA stationary liquid, and fixing for 48 hours;

3) dehydrating the plant of step 2), namely: ethanol water with different concentrations of 65%, 765%, 85% and 95% is used, and the time interval of each gradient is 2 hours;

4) putting the plants in the step 3) into 100% for dehydration for 1 hour, taking out the plants, putting the plants into acetone, and continuously dehydrating for 30 minutes;

5) application of co₂Critical point drying method, which is to dry the plant of the step 4) at critical point;

6) cutting the plant in the step 5) at a 90-DEG C angle which is perpendicular to the upper part of the test material by using a double-sided blade, so as to cut off the conglomerated blocking object after the protoplast is dried in the plant-grain cell structure;

7) making the plant residue in the step 6) into an identification material for scanning electron microscope plant texture;

8) sticking the plant scraps in the step 7) on a sample table, and sputtering a gold coating film by using IB-3 ions;

9) the gold-plated material of step 8) was observed and photographed using a scanning electron microscope.

2. The method of claim 1, wherein the step of identifying the texture of the gold effectively plated by the scanning electron microscope comprises the steps of:

step 8) sputtering gold-plated film with IB-3 ions with thickness of 200A.

3. The method of claim 1, wherein the step of identifying the texture of the gold effectively plated by the scanning electron microscope comprises the steps of:

step 9) was observed using a scanning electron microscope and the photographing voltage was 20 kV.

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