"Flaw?" Master Kang liked this word the most, especially at this moment, when he felt a little out of breath due to Zhu Ruiping's aggressive attitude.

Gu Chen's words were undoubtedly timely.

Secretary Zhou also stared at Gu Chen with wide eyes and asked: "Officer Gu, you said that Zhu Ruiping's mortgage document is a fake. What evidence do you have?"

"Yes, you... what evidence do you have? Why do you say that my mortgage document is fake? You are slandering me."

Hearing the conversation between Secretary Zhou and Gu Chen just now, Zhu Ruiping also knew that the person standing in front of him, accusing the house deed mortgage document in his hand of being a forgery, was a police officer from the Criminal Investigation Team of Furong Branch of Jiangnan City, and he couldn't help but feel nervous.

.

But he was nervous. When the situation reached this point, Zhu Ruiping had no choice but to retreat. He would never give in.

"No need to pretend to be aggrieved and angry." Gu Chenyun looked at Zhu Ruiping calmly, then flipped the yellow paper back and forth, and said with a smile: "As for your handwriting, although it is the handwriting of Mr. Kang when he was alive, it is correct.

, but it’s not necessarily written by Mr. Kang.”

"What...what do you mean?" Zhu Ruiping looked at Gu Chen in confusion.

Gu Chen smiled and said: "In other words, with your handwriting, you can definitely find a calligraphy master to copy Mr. Kang's calligraphy handwriting and habits and copy it out to create a mortgage letter with exactly the same handwriting."

"ah?"

"Can I copy it?"

"Why didn't we think of this before?"

"Yes, if you are a master of calligraphy, you can definitely write this kind of handwriting. For example, many people have completely understood Wang Xizhi's calligraphy. If the fakes are placed in the exhibition hall, they will be the same as the real ones.

It’s the same.”

After listening to Gu Chen's words, many people suddenly realized that it was obvious that the situation Gu Chen mentioned was entirely possible.

Zhu Ruiping was dissatisfied and said: "But...but this is just your one-sided statement and a hypothesis. There is no real evidence at all. Why do you say that this mortgage document was forged by copying the handwriting?"

"Yes." A senior executive standing behind Zhu Ruiping immediately stood up, pointed at Gu Chen's nose and said, "You policeman is so ridiculous. You just copied what you said? This is something from the past.

, the paper is yellowed, it is obviously something written by Mr. Kang himself back then."

"It's okay if you don't tell me." Seeing the aggressiveness of the other executive, Gu Chen just shrugged and walked to him easily.

The Zhu family executive, who was half a head shorter than Gu Chen, immediately took two steps back, kept a relatively safe distance from Gu Chen and said, "That's right."

"Then have you ever considered why this paper turned yellow?" Gu Chen's soul torture immediately stunned the Zhu family executives opposite.

He only knew that the paper would turn yellow after being stored for a long time, but he really never thought about why it turned yellow.

"I can tell you." Gu Chen smiled and took two steps forward: "Because paper is made of bleached acidic substances. Although it is neutralized before leaving the factory, there will still be residual substances left behind.

Above, over time, the paper will be oxidized and turn yellow. In fact, the components of the paper are oxidized."

"So...it turns out to be like this." The Zhu family executive was stunned, and the arrogance just now calmed down a lot.

Gu Chen then walked up to Zhu Ruiping and said: "Lignin is one of the main components of plant fiber. It has aromatic properties and is a compound containing carbon, hydrogen, and oxygen. According to chemical analysis, lignin Contains the following functional groups."

"Wait a minute." Zhu Ruiping suddenly interrupted Gu Chen and asked, "What is this 'functional group' you are talking about?"

Gu Chen smiled: "Functional groups are atoms or groups of atoms that determine the chemical properties of organic compounds. Do you understand?"

Zhu Ruiping seemed to understand but not quite.

I was originally a bad student. Although I went to the United States to study abroad, it was just a pheasant university.

However, Zhu Ruiping still has some vague concepts about atoms and atomic groups.

"You... just say it." Seeing Gu Chen staring at him, Zhu Ruiping had no choice but to shut up again.

Gu Chen looked back and then said: "I just said that the functional groups contained in lignin actually include methoxy groups, hydroxyl groups, carbonyl groups, aldehyde groups and ether bonds, etc."

"Lignin is white or nearly white, insoluble in solvents, fragile in texture, and can be dissolved at high temperatures, and its solution is milky white or dark brown."

"Because lignin contains various functional groups, its chemical properties are relatively active. For example, sulfonation reaction occurs, turning lignin into soluble lignosulfonate, and oxidation into soluble chlorinated lignin."

"But lignin is the most easily oxidized, especially in the presence of light, high temperature and alkali, oxidation is more rapid."

"Modern paper also contains a lot of lignin, so newsprint can easily turn yellow and become brittle, making it difficult to store for a long time."

"That's right." After hearing this, Lu Weiwei couldn't help but interjected: "My old newspapers are the most likely to turn yellow, and they are yellow and brittle and can be broken with just a pinch."

"I have some at home too." Nie Xiaoyu couldn't help but say a few words: "I have a lot of these old newspapers at home. It's really the same as what brother Gu Chen said. It turns out that there are so many chemical factors in it. ."

Zhu Ruiping was obviously confused by what Gu Chen said.

He could finally tell that the young man standing in front of him was obviously a top student.

At the very least, the fact that he can blurt out this seemingly complicated knowledge is enough to show how strong the knowledge reserve in his mind is.

Most people, even if they occasionally see it in the library, may not remember it so well.

But the young man in front of me can do it, which is a bit scary.

Seeing that Zhu Ruiping stopped talking, Gu Chen smiled and said: "So, it can be seen that because the papermaking raw materials contain plant fibers, especially lignin, pectin, fat, pigments and other ingredients, it lays the foundation for the harm of paper. There are potential factors, so there are these problems, but this yellow paper of yours..."

Gu Chen deliberately scratched the corner of the yellowed mortgage document with his finger.

However, to everyone's surprise, the paper was intact. Gu Chen continued to press hard, and then a corner of the paper began to be removed.

"Tsk, tsk, paper that is about 20 years old is not as crisp as it is more than 20 years old." Gu Chen looked at Zhu Ruiping again.

Zhu Ruiping was a little panicked, and even wanted to back down. However, at this time, another tall and thin middle-aged executive with black-rimmed glasses and a capable appearance appeared next to Zhu Ruiping again.

He was like a staff general, showing a trace of disdain for Gu Chen's questions.

"I said this young man, oh no, should be called Comrade Police, right?" The tall, thin man with glasses said with disdain on his face.

Gu Chen shrugged: "Whatever, do you have anything to say?"

"Humph." The tall, thin man with glasses chuckled twice and said, "What you said is all right, but you also need to know that if I can do these three points, the paper will turn yellow or reduce its crispness.

It’s completely achievable.”

Seeing that the other party was full of confidence, Gu Chen nodded, stretched out his hand and said, "I would like to hear the details."

"This is number one." The man imitated Gu Chen's impressive morale, raised his head, put his hands behind his back, walked to Master Kang, and said:

"The first point is to reduce contact with air, the second point is to reduce contact with moisture, and the third point is to reduce contact with sunlight."

Gu Chen crossed his arms to his chest, held his chin and thought for a few seconds, then nodded and said, "Yes, everything you said is right."

Seeing Gu Chen's approval, the tall, thin man with glasses who looked like a top student suddenly became quite proud and said:

"Most people cannot avoid contact with air, but they can try to avoid contact with moisture and sunlight."

"If you don't use certain books often, you can try putting the books in a plastic bag and sealing them, then take them out when you need them."

Gu Chen nodded: "Please continue."

The tall, thin man with glasses smiled and walked up to Secretary Zhou again: "Usually, the storage period of paper should not exceed one year. No matter how good the conditions for storing paper are, if the paper is stored for too long, it will change color and deteriorate."

"If the paper is stored for more than two years, the coated paper will turn yellow and lose powder, the newsprint will turn yellow and become brittle, the wrapping paper will change color and its strength will decrease, and the yellow paperboard and boxboard paper will become moldy and deteriorate, etc."

Seeing that everyone in the scene suddenly fell silent, as if this was his stage, the tall, thin man with glasses suddenly felt proud, and the corner of his mouth raised a confident arc.

He continued to smile at Gu Chen and said: "So generally, the white paper we use is made from fiber pulp formed by processing tree fibers in paper mills and laid flat on a flat plate to dry in the sun."

"But you can imagine the color of the cross-section of a tree trunk. The wood fibers are slightly yellow, so sulfur dioxide is used in industry to bleach paper."

"However, the bleaching of sulfur dioxide is not as stable as chlorine. It is easily oxidized to sulfuric acid by oxygen and loses its bleaching effect. In this way, the color of the wood fiber itself is exposed, which is what Officer Gu said before."

Gu Chen continued to nod but said nothing.

"Sulfuric acid will destroy the fibers in the paper." The tall, thin man with glasses raised his right index finger, as if he was an expert teaching a group of students, and said confidently:

"As a result, the paper will become brittle. In addition, excessive dryness of the paper and the oxidation of the lignin in the paper will also cause the fibers to break and cause the paper to become brittle."

"So, if the three points I mentioned before can be achieved, what about the yellowing of the paper? The brittleness of the paper can theoretically meet the requirements of your experiment just now."

"Okay." Zhu Ruiping suddenly became excited when he saw that his senior executives were able to PK Gu Chen.

He patted the tall, thin man with glasses on the shoulder, almost knocking the man's black-rimmed glasses off.

The tall, thin man with glasses immediately adjusted his glasses, straightened his shirt proudly, puffed out his chest and raised his head, exhaled, and looked at Gu Chen with arrogance like a victorious rooster.

Lu Weiwei was stunned.

Nie Xiaoyu was also stunned.

Including Police Officer Wang, Master Kang, Bai Xiaolan, Wu Jun from the TV station, Secretary Zhou and the foreign business people, all were shocked by the words of the tall, thin man with glasses just now.

He directly used his own theory to deny Gu Chen's previous experiment and made a reverse proof.

It proves that the situations mentioned by Gu Chen also exist as special circumstances.

A high salary is not free. You have to stand up and help the boss solve problems at critical moments. This is what the tall, thin man with glasses is experiencing now. It feels so good that he doesn't want to go without it.

He was so excited that he wanted to high-five Zhu Ruiping to celebrate, but due to the environment, he restrained himself.

Gu Chen suddenly covered his mouth and started laughing, which made Lu Weiwei and Nie Xiaoyu beside him confused.

The tall, thin-eyed man just now was so aggressive with Gu Chen, how could Gu Chen still laugh?

This doesn't look like Gu Chen's style at all?

Master Kang was also anxious: "Gu Chen, it's already this time, how can you still laugh? If that guy with glasses said this, doesn't that mean it confirms that their mortgage document is true?"
To be continued...