The copyright of the original article belongs to the WeChat public account
"Bring Science Home" All articles written by
| Mirror
Can boiled eggs become raw eggs?
Image source: Pixabay
Recently, an article claiming that "cooked eggs are reborn and hatched chicks" has set off a hot search.
Leaving aside this "Shibian Nights", with the existing technology, is it possible for a boiled egg to come back to life?
As early as 2015, there were research reports on the rebirth of overcooked eggs, and they also won the Ig Nobel Prize in Chemistry that year.
But this is actually exaggerated propaganda by the media. The so-called "cooked eggs" in this 2015 paper are just boiled egg whites. The purpose of this experiment is not to turn boiled eggs into raw eggs, but to study how to efficiently convert denatured eggs. The protein renaturation is used in medical and other fields. The
protein is formed by connecting and folding the polypeptide chain (long chain of amino acids), and it needs to maintain a specific three-dimensional structure in order to play a specific function. However, the connection between polypeptide chains (, disulfide bond, , etc.) is not very reliable. Adding acid, alkali or heating will destroy it, disrupt the protein molecular structure, and tangle with surrounding protein molecules. The coagulation of egg whites into egg whites is the process of denaturation of proteins under heating conditions.
Schematic diagram of the heating and solidification process of egg white | Source: Australian Academy of Science
To reverse this process, that is, it is not easy to achieve renaturation. Biological laboratories generally use urea to loosen the structure of denatured proteins, and then after a long period of dialysis , waiting for the protein to refold and renature.The 2015 study changed the time-consuming dialysis method to use a vortex fluid device (VFD) . The shear force generated by the high-speed rotation of the VFD continuously pulls on the protein, reshaping its shape and achieving a certain degree of renaturation in just a few minutes.
In addition, the protein used in this experiment is not ordinary boiled protein, but the egg white diluted with phosphate buffered saline (PBS) after being boiled at 90 ℃ for 20 minutes, and only focus on egg white lysozyme The renaturation of several proteins such as . This method could not completely renature all proteins, among which the egg white lysozyme activity recovered better, reaching more than 80%.
However, the composition of the whole egg is far more complicated than this. Not only are there more types of proteins, but also macromolecules such as nucleic acids and fats. Besides, life is not a simple pile of substances, so it is undoubtedly nonsense to bring boiled eggs back to life.
Why does high fever often happen at night?
Source: Pixabay
Many parents have the experience that their children often have a high fever in at night. Not only children, but a survey shows that hospital receives far more adult fever patients in the evening than in the morning.
During the day, everyone is more active and busy, and may ignore the fever, but the human body itself does contribute to the fire at night.
Although we are warm-blooded animals, our body temperature is not absolutely constant. There are fluctuations within 1°C throughout the day, usually the lowest at 4-5 in the morning and the highest at 4-6 in the evening. The basic body temperature of young children is slightly higher than that of adults, and it is easy to have a high fever at night, and there is also a fire from basal body temperature.
Fever is the reaction of the immune system against pathogens, some immune cells work more actively after we fall asleep, and children's immune systems are immature and tend to react more violently, which may also cause high fever.
Not only fever, but also asthma and other diseases will be aggravated at night. During the day, the human body secretes cortisol and adrenal hormone to help relax the airways and relieve asthma, but the levels of these hormones gradually decline at night, causing asthma to worsen. In addition, the increased secretion of melatonin at night is originally a sleep aid, but for asthmatics, it can aggravate inflammation, make the airways produce more mucus, and cause dyspnea.
The hot air will rise. Why does the higher the altitude of , the lower the temperature of ?
Source: Pixabay
"The temperature decreases with the altitude" is the basic knowledge that everyone has learned in geography, but we also know the phenomenon of "warm air rises and cold air sinks", and the high altitude is closer to the sun , Why isn't the temperature higher at higher altitudes?
In fact, the law of "temperature decreases with increasing altitude" does not apply to the entire atmosphere, and it is indeed true for the troposphere (tropopause) at the bottom of the atmosphere. But in the higher stratosphere (stratosphere) the temperature first stabilizes and then rises. Going up to the middle layer (mesosphere) , the temperature begins to drop again with the increase of altitude, reaching the lowest point of the atmospheric temperature . Then to the thermal layer (thermosphere) , the temperature began to rise again, and even reached thousands of degrees Celsius .
The relationship between air density (Density), air pressure (Pressure), speed of sound, temperature (Temperature) and altitude (Geometric altitude) | Source: Wikipedia
On air density alone, the higher the altitude, the higher the air Lean, that is, the fewer gas molecules per unit volume. However, the efficiency of the air itself absorbing the heat is not high, and the heat source of the troposphere is mainly the surface . A large part of the heat from sunlight is absorbed by the earth's surface and then radiated into the air. The heated air will go up, but in the process of rising, because the air pressure becomes lower and expands continuously, it is equivalent to doing external work, which needs to consume internal energy, and the temperature drops accordingly.
The reason why the temperature in the upper stratosphere starts to rise is because it has ozone layer which absorbs the heat of ultraviolet rays. The thin air in the middle layer has neither the ground to provide heat, nor enough ozone to absorb ultraviolet rays, and the short-wave radiation of the sun is first absorbed by the upper thermal layer, so the temperature begins to drop again. In the thermosphere, the temperature rises rapidly because it is irradiated by strong ultraviolet rays and cosmic rays, and even the gas molecules are ionized.
Why should there be two nostrils ?
Image source: Pixabay
Many organs are paired: two eyes allow us to perceive the depth of the scene and form a stereo image; What's the point of nostrils?
Neuroscientists have found that this expands our sense of smell.As we mentioned in the past, the two nostrils work alternately. Every few hours, one nostril is dominant, and the inner wall of the other nasal cavity expands, narrowing the channel and restricting the passage of air.
Stanford University neuroscientists recruited 20 healthy volunteers and asked them to smell a mixture of carvone and octane , using only one nostril at a time. The results showed that most volunteers smelled more carvone when they smelled through their dominant, open nostril, and more octane when they smelled through the other, less open nostril.
The body absorbs carvone quickly and octane slowly. Blocked nostrils may have slowed the flow of gas, allowing octane to stay in the nasal cavity for longer and to perceive its odor more fully.
The two nostrils, one open and one blocked, combined with speed and slowness, endows us with a richer olfactory experience.
is not enough? Pay attention to the WeChat public account "Bring Science Home", and catch all interesting and informative popular science!
