In the lecture theater, Lu Weiwei’s performance really made people’s eyes shine.
Everyone knows that Lu Weiwei, like Officer Wang, is from the Criminal Investigation Team of Furong Branch, Jiangnan City.
For forensic doctors, both of them were laymen, but instructor Zhang Hui's questions were not difficult for them.
This made many forensic doctors who wanted to see a joke suddenly feel disappointed.
Zhang Hui was stunned for a moment, and then he recovered from his surprised eyes: "Very...very good, please sit down."
Lu Weiwei nodded, sat down, and blinked her right eye at Gu Chen.
However, there was suddenly a burst of whispers at the scene.
"The police in Furong Branch of Jiangnan City are really powerful."
"Yes, he blurted out two questions in a row, which shows that his knowledge reserve is not ordinary."
"Damn, are all the top students sent by Jiangnan City this time? No wonder they can come to participate in the training."
…
It was also when everyone lowered their heads and whispered, the bald instructor Zhang Hui coughed twice, and the scene gradually became quiet.
"The female student just said it well. Yes, these characteristics make diatoms widely used in red tide detection, aquaculture, water quality monitoring, resource surveys, paleoenvironmental analysis, oil exploration, forensic identification and other fields.
"
"Moreover, diatoms belong to the class Diatoms of the phylum Bacillaria in algae. They are a type of phytoplankton. They are found wherever water lags on the earth, ranging from small puddles formed by rainwater to as large as 71% of the earth's surface.
You can almost see traces of diatoms in the ocean.”
"There are also some diatoms that grow as terrestrial types on the surface of moist soil and on the exposed surfaces of other objects. Some of them are also floating in the air."
Looking up and glancing in the direction of Gu Chen, Zhang Hui found that Officer Wang and Lu Weiwei were high-fiving Gu Chen in celebration.
Suddenly the slack brows knitted together again.
Zhang Hui coughed twice and said absently: "We all know that there are more than 16,000 kinds of diatoms in the world, with body lengths generally ranging from 1 to 200 μm. Diatoms are sensitive to water quality, and the diatom communities are also different in different water environments."
"The most obvious feature is that the cell wall, except for a few species, is highly siliceous, forming an upper and lower transparent shell. The shell rings are connected to form a siliceous cell wall. It is hard and stable, not easily destroyed, and cannot be damaged.
Affected by corruption and death.”
"Even if concentrated sulfuric acid or concentrated nitric acid is boiled, it is difficult to destroy its texture characteristics, so based on these characteristics, diatoms play a significant role in forensic detection."
The PPT picture quickly turned over and entered the next stage of blue background copywriting.
Zhang Hui suddenly stood up, came to the podium and wrote some copywriting information on the whiteboard.
Looking back at everyone, Zhang Hui tapped the whiteboard with the back of his hand and marked the key points.
"Everyone has paid attention to this. Everyone remembers this. Due to the active breathing of the person who entered the water before death, diatoms can be inhaled into the alveoli along with the drowning fluid, enter the blood circulation, and be distributed to various tissues and organs."
"Furthermore, through qualitative and quantitative analysis and comparison of organ tissues and diatoms in the water, not only can the cause of death be directly determined, but it can also help to infer the location of drowning."
Upon hearing this, the forensic scientists also copied the transcripts into their transcripts.
Everyone may be aware of these, but many people are learning about the characteristics of diatoms for the first time.
Therefore, regardless of whether they were forensic doctors who knew it or not, everyone bowed their heads and took notes.
The scene was very harmonious, but only Gu Chen in the corner of the back row remained unmoved.
But it wasn't that Gu Chen didn't want to take notes, it was just that Gu Chen had already seen this information in the city library a few months ago.
What instructor Zhang Hui just said, Gu Chen has already used his professional memory to perfectly record in his mind.
The answers given by Officer Wang and Lu Weiwei just now are the best reflection of verifying their own memories.
Zhang Hui felt that Gu Chen was a little disrespectful.
From the beginning of the lecture to now, Gu Chen has hardly written any words. This is a very unusual existence in the highly dogmatic training system.
Zhang Hui frowned and continued: "Now we are going to talk about a long-standing problem, which is the identification of the cause of death of corpses in the water."
Looking at Gu Chen's indifferent expression, Zhang Hui curled his lips and smiled: "I need a teaching assistant now to help me write on the whiteboard. I wonder... which student is willing?"
The scene was silent for a few seconds, and several students in the front row raised their right hands one after another.
However, after Zhang Hui pretended to observe, he suddenly pointed at Gu Chen and said: "Just... that student, yes, it's you, the one sitting in the last row next to the female student who just answered the question."
"Me?" Gu Chen was suddenly called by name and stood up to confirm.
Gu Chen then walked out of his seat and walked along the stairs to the podium under the eyes of everyone.
Zhang Hui handed the oil-based pen to Gu Chen and said with a smile: "Student, please stand here and help me write on the whiteboard."
"No problem." Gu Chen nodded slightly, took the oil-based pen, and went directly to the whiteboard.
Zhang Hui breathed a sigh of relief and thought to himself, this little comrade was standing on the podium listening to his lecture, so he should be able to concentrate, right?
Thinking about it, it's also good for him...
So Zhang Hui sat back in his seat and continued to lecture.
"We just talked about a long-standing problem, which is the identification of the cause of death of corpses in the water."
"Tuk-tuk-tuk-tuk..."
As soon as Zhang Hui finished speaking, Gu Chen had already written the six characters "Corpse Cause of Death" on the top of the whiteboard.
Zhang Hui took a peek and was quite satisfied, so he continued: "Everyone should know that drowning is a way of death caused by liquid blocking the respiratory tract and alveoli, hindering gas exchange, resulting in lack of oxygen in the body and retention of carbon dioxide, leading to suffocation."
As soon as he finished speaking, Gu Chen had already listed several key points, almost simultaneously.
Zhang Hui didn't pay attention, but continued: "According to the "Global Drowning Report" released by the World Health Organization in 2004, 342,000 people drowned in the world every year, with an average of 42 deaths per hour."
"According to statistics, about 60,000 people drown in our country every year. Drowning is the third cause of accidental death in our country and the first cause of death in children under the age of 14."
This chapter is not finished yet, please click on the next page to continue reading the exciting content! After seeing himself finish speaking, Gu Chen suddenly stopped writing.
Zhang Hui glanced at him and reminded: "Write it down."
"Instructor, your data doesn't seem to be very accurate." Gu Chen had no intention of continuing, but instead questioned Zhang Hui.
The scene suddenly became lively...
No one expected that Gu Chen would question instructor Zhang Hui's data face to face. In everyone's opinion, was Gu Chen too conceited?
For a time, everyone in the audience was talking about it.
When Zhang Hui saw this, he asked Gu Chen angrily: "This student, what is your name?"
"Gu Chen." Gu Chen said.
"Which unit are you from?" Zhang Hui asked again.
"Criminal Investigation Team Three of Furong Branch of Jiangnan City." Gu Chen said.
Zhang Hui suddenly laughed and said: "Gu Chen, I have read your file. You are not a forensic doctor, right?"
Gu Chen nodded.
"Then why do you question whether my data is wrong?" Zhang Hui asked again.
Gu Chen did not speak, but changed the "Global Drowning Report" released by the World Health Organization in 2004 to 2014.
Later, the figure of 342,000 drownings worldwide every year was revised to 372,000.
Zhang Hui was suddenly stunned. He quickly lowered his head and looked at the information in his hand, but was suddenly startled.
There was nothing wrong with the data Gu Chen modified, but there was a data error in the data he had on hand.
Indeed, the statistical report is from 2014, but my own data is from 2004, which is a full 10 years difference.
The number of drowning deaths in 2014 was 372,000, but the data I had on hand was 342,000, which was a total difference of 30,000.
Zhang Hui was suddenly a little surprised...
"How did Gu Chen know this? He could actually know that my data was wrong? Isn't this incredible?"
Zhang Hui felt frightened, but he picked up the information in his hand, pointed at the assistant teacher Yang Ting and said: "Xiao Yang, you compiled this information, right?"
"Yes." Yang Ting nodded silently: "It was compiled according to your manuscript."
"Look at you, you are careless." Zhang Hui threw the A4 paper information on the table and said angrily: "You typed these data wrong."
"Is it a big mistake to hit...?" Yang Ting heard this and quickly checked herself: "No way? How come it was a mistake?"
Zhang Hui picked up the manuscript, tapped it with his fingers and said: "On my manuscript, it clearly says that according to the "Global Drowning Report" released by the World Health Organization in 2014, 372,000 people drown in the world every year, with an average of 42 deaths per hour.
people."
"And look what you have sorted out? 2014 turned into 2004, and 372,000 people turned into 342,000 people. Are you too careless?"
"Really?" Yang Ting suddenly panicked.
She quickly took out the manuscript Zhang Hui gave her from the document bag and opened a few pages for verification.
After a moment, Yang Ting was dumbfounded: "It's really a mistake."
Glancing at Zhang Hui, Yang Ting lowered her head and apologized, saying, "I'm sorry. Maybe I typed too fast and didn't verify it clearly. I'm really sorry."
"Okay, be more careful next time." Zhang Hui also waved his hand, asking Yang Ting to sit down first, and then said:
"Our work must be rigorous. This time it is just a report. Next time if there is a data error during the laboratory operation stage, it will not be serious. It is very likely that the results of everyone's efforts will be in vain."
"Yes, yes, it's my fault." Yang Ting was also brave enough to take responsibility for her mistakes, but she didn't quite understand: "But...how did Gu Chen know that my data was wrong? I didn't even show him the manuscript?
"
"Yes, how did Gu Chen know?"
There were many people at the scene who had the same doubts as Yang Ting.
Do you know this kind of data? I wonder if you can even memorize the Xinhua Dictionary?
Zhang Hui was also stunned. Yang Ting's question just now made him feel confused.
There was an error in his own data, but Gu Chen was able to discover the problem immediately.
More importantly, he was able to accurately express the real statistical data, which shows that Gu Chen also understands this report.
Zhang Hui looked Gu Chen up and down, and then asked him: "Gu Chen, how did you know?"
"I have read the Global Drowning Report released by the WHO in 2014," Gu Chen said.
"Have you seen it?" Zhang Hui was doubtful and continued to ask him: "Have you ever been exposed to this?"
"I saw it in our Jiangnan City Library a few months ago." Gu Chen said.
Zhang Hui pinched his chin and said in disbelief: "But...it has been a few months, and you can even remember these data now?"
"I remember, but I also remember that the health organization estimated that the actual number may be twice as high."
"That's very good." Seeing that Gu Chen could accurately tell these data, Zhang Hui's eyes changed when he looked at Gu Chen.
I feel that this young man has an extraordinary memory, far better than others.
After feeling ashamed for a while, Zhang Hui picked up the writing pen on the table, corrected the data, and then said:
"After all, due to the dense seawater network of rivers and lakes in our country, a huge number of drowned corpses need to be identified every year."
"Most of the drowned corpses found in rivers, lakes and seas are accidental deaths of drowning people, but some drowning people have committed suicide or homicide, and it is not ruled out that the body is thrown into the water after death and is faked as an accidental drowning death.
."
Zhang Hui glanced at Yang Ting, who immediately switched slides.
At this moment, what is displayed on the screen is a picture of a city river.
One side of the city's river was cordoned off, while next to the river was a blue tent temporarily erected by the police.
Zhang Hui coughed twice and continued: "Drowning deaths have occurred from time to time in recent years, but detection is also very difficult."
"It's okay to have witnesses, because they can determine the cause of death. But for those who drowned without witnesses, detection technology needs to be used."
"For fresh corpses in the water, drowning can be identified through typical signs of drowning such as mushroom-like foam in the mouth and nose, watery emphysema, and silt in the respiratory tract."
This chapter is not over yet, please click on the next page to continue reading! "However, when more than 80% of the bodies in the water were discovered, they were highly corrupted and all signs of drowning no longer existed."
"In addition, autopsy and histological examination will determine whether there are specific pathological changes related to drowning. The identification of the cause of death has become a world-recognized problem, and the cause of death is the key to the characterization of the case."
After a pause, Zhang Hui saw that Gu Chen had already written down the key points, and couldn't help but said: "This involves police handling."
"Because the cause of death is unknown, the case cannot be determined, which can easily lead to dissatisfaction among family members, public opinion speculation, and media hype."
"So our forensic doctors must perform accurate tests to find out the cause of death and give the family a satisfactory explanation, otherwise it will cause big trouble."
Seeing Gu Chen's tacit cooperation on the whiteboard, Zhang Hui's attitude improved a lot and he asked Gu Chen casually: "Gu Chen, do you know any famous examples?"
Gu Chen stopped writing, thought about it carefully, and then said: "The 'Lan Ke'er Incident' that occurred in the United States in February 2013 is a typical example."
"That's right." Zhang Hui nodded slightly and said to everyone in the audience: "So, incomplete investigations will cause many social problems, which requires us to be rigorous in our work, so this puts forward higher requirements for our forensic testing.
"
Looking at Gu Chen, Zhang Hui said again: "Gu Chen, do you know what experiments our forensic scientists have done to solve the problem of identifying the cause of death of corpses in the water?"
The scene suddenly became quiet, and everyone was sweating for Gu Chen.
I wonder if instructor Zhang Hui is relying on Gu Chen?
You can't just pick one person when shedding wool, right? Don't you give others a chance?
In fact, many forensic doctors in the audience also knew something about it, but Zhang Hui only gave the opportunity to answer to Gu Chen, and also wanted to test the young man's true level.
After Gu Chen thought briefly for a few seconds, the data stream in his brain began to tumble rapidly, and it soon came to mind.
Gu Chen raised his head and said: "Forensic medicine workers have successively studied methods such as diatom testing, blood biochemical testing, foreign element testing, plant pollen spore testing, and chlorophyll a testing."
"However, except for diatom testing, other methods are limited to experimental research and have not been promoted and applied in forensic practice."
"That's very good." Zhang Hui was very satisfied with Gu Chen's answer, so he smiled and said, "So diatom testing, as I said, is the 'gold standard' for drowning diagnosis."
"As for how to determine whether someone entered the water before death or dumped the body into the water after death, diatom testing has always been the most commonly used method in forensic practice."
"But there are also doubts and controversies." Gu Chen retorted directly.
Zhang Hui frowned and felt a little unhappy. He thought to himself that Gu Chen was here to cause trouble, right?
But what Gu Chen said was correct. Just when Zhang Hui was about to speak, another first-level police inspector sitting next to him said: "Gu Chen, you said there are doubts and controversies about diatom testing. Why?"
"Because currently, most forensic doctors at home and abroad use optical microscopes to detect diatoms in the organ tissues of drowning victims."
"Although the method of diatom inspection technology cannot directly determine the exact cause of death of drowning victims, it can help determine the death place of drowning victims by comparing the types and quantities of water samples at the places where drowning deaths occurred.
positive effect."
Gu Chen connected seamlessly and expressed his views, and then said:
"Although diatom testing has been used in the diagnosis of drowning for more than 100 years, the value of diatom testing has always been controversial, mainly because of the current diatom testing technology used by forensic circles around the world.
There are many.”
Having said this, Gu Chen directly picked up the oil-based pen and wrote on the whiteboard: "The main method is to extract and digest the sample and then use the diatom enrichment method and diatom observation method."
Looking back at the people in the audience, Gu Chen stepped forward and explained to everyone: "Because diatoms are widely distributed in nature, they are commonly found in fresh water, sea water, air and food, especially vegetables."
“In addition to the passive contamination of corpses in the water, atypical drownings, corpses entering the water after death, and corpses that died in waters lacking diatoms, as well as the pollution problems of the experiment itself, including containers and reagents, etc., diatoms
The role of testing in diagnosing drowning has been controversial."
When everyone heard this, they nodded frequently, it seemed that what Gu Chen said made sense.
However, Gu Chen's old habit relapsed, and he instantly regarded this place as a crime scene, and couldn't help but explain to everyone: "In fact, diatom testing laboratories at home and abroad have always used strong acid boiling and digestion, centrifugal enrichment, and light microscopy observation.
technology."
"These traditional technologies actually have significant shortcomings. In addition to the above-mentioned pollution problems, they are also manifested in... low recovery rate of diatoms extracted from organ test materials, poor test sensitivity, and high false negative rate."
"Diatoms are small in size and low in content. Due to the limited magnification of the light microscope, problems of missed detection or false detection are prone to occur."
"Ahem." Seeing that Gu Chen had taken away his right to speak, instructor Zhang Hui complained a little and quickly coughed twice as a reminder.
However, Gu Chen didn't pay attention at all. He snapped his fingers and continued: "Diatom testing requires species identification of the diatoms being tested."
"Forensic examiners usually lack professional knowledge of diatom taxonomy and misjudge the attributes of other foreign objects as diatoms, which to a certain extent restricts the application of diatom testing in the diagnosis of drowning."
"Okay... okay." Seeing that Gu Chen kept talking and had no intention of stopping, instructor Zhang Hui was a little flustered and quickly interrupted: "Gu Chen, you'd better sit back."
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