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April 25th, 2016 is the 31st National Child Vaccination Day in China, and "Vaccination-Protecting Health" is the theme of this year’s activities.

Children, especially newborns, are particularly vulnerable to infectious diseases because of the imperfect immune system. Vaccination can prevent injury, disability and death caused by diseases including diphtheria, hepatitis B, measles, mumps, whooping cough, pneumonia, poliomyelitis, rubella, tetanus and various epidemic encephalitis.

According to the statistics of the World Health Organization, vaccination can avoid 2 million to 3 million deaths every year. Taking DTP vaccine as an example, in 2014, about 86% (115 million) infants in the world received three doses of DTP vaccine, thus avoiding infectious diseases that can lead to serious diseases, disability or death. By 2014, the coverage rate of DPT vaccine in 129 countries has reached at least 90%.

The improvement of vaccine coverage has greatly improved the living conditions of children. Therefore, vaccination is an important tool to protect children’s health. It is also very necessary to vaccinate children in time and accurately. Below we will explain the principle, safety and public access to information of vaccination from several different aspects.

How can vaccines protect children’s health?

Vaccines are artificially prepared pathogen analogues or inactivated pathogens. Vaccination can make the body’s immune system "remember" the pathogen. Once the real pathogen invades, it can immediately produce antibodies and remove the pathogen. For children, vaccination can help them to strengthen their "memory" and defense against pathogens and protect them from harm when their own immune system is imperfect. So vaccination is very necessary.

How to determine the safety of vaccine?

As a special drug, vaccine has been strictly controlled and supervised from research and development, production, circulation to use. As parents, you can determine the safety of the vaccine from the following three aspects:

First, the electronic supervision code. The drug supervision department of our country has strict supervision over the production and circulation of vaccines. Each vaccine has an ID number "electronic supervision code", and each vaccine has one code. Parents can find this code on the product packaging box of the vaccine, and then query it on the website of "China Drug Electronic Supervision Platform". The production and circulation of vaccines will be inquired by parents in the database, and parents can inquire whether the vaccines vaccinated by their children are under normal supervision.

Second, the vaccine temperature indication label. It is a circular piece of paper (as shown in the following figure). The color of the circular reference ring is the standard color, and the box inside the reference ring is coated with paint sensitive to light and heat. Once the vaccine leaves the cold chain for a long time in the circulation process, the paint in the box will change color, and the vaccine with serious color change can be judged as invalid. Fig. a shows the color of the indicator label of the vaccine just delivered from the factory; The box color in Figure B begins to get darker, but it is still lighter than the ring color, and the vaccine can still be used; Figure C, the color of the box is consistent with the color of the reference ring, indicating that the vaccine has been out of the cold chain for too long and the vaccine has failed; In Figure D, the color of the box is darker than the color of the reference ring, and it is also judged that the vaccine is invalid. It should be noted that the vaccine temperature indication label must be used within the shelf life of the vaccine, and the vaccine beyond the shelf life, regardless of the color of the label, is invalid and cannot be used. The vaccine temperature indication label is not mandatory, and parents can choose it by themselves.

Third, choose qualified inoculation sites to inoculate children. If parents have doubts about the qualification of the inoculation point, they can consult the local health administrative department or its designated department, and the consultation channel can be inquired from the government website of the relevant department.

Will there be adverse reactions after vaccination? How to avoid it?

Vaccine is an analogue of a pathogen, even an inactivated pathogen itself. Because of individual differences and imperfect immune system, it is possible for some children to have adverse reactions to it. Adverse reactions include redness, pain and induration at the inoculation site, or symptoms such as fever and fatigue, which can be cured by general treatment. The probability of strong adverse reactions such as thrombocytopenic purpura is extremely low, with only a dozen cases every year. For these children, the state also has corresponding treatment and compensation measures.

In order to avoid adverse reactions during vaccination to the greatest extent, parents should be aware of their children’s physical condition before vaccination. For example, whether you are allergic, what are you allergic to? Are you sick recently, acute or chronic, and is the chronic disease in acute attack or stable period? Under normal circumstances, if children are allergic to any ingredients contained in the vaccine, they cannot be vaccinated; For children with allergies whose allergens are unknown, because of the possibility of being allergic to the vaccine, parents should check their allergic history with doctors before deciding whether to vaccinate; It is not suitable for vaccination in acute attack period, and some vaccines can be selectively vaccinated in stable period of chronic diseases. In a word, parents need to communicate with doctors before vaccination. Different vaccines have different requirements for physical condition, and doctors will give reasonable suggestions. 24 hours after vaccination, you should pay close attention to your child’s condition. If you have any adverse reactions, you should seek medical advice in time.

How to get official information?

If parents still have doubts about their children’s vaccination, please visit the official website of "China Center for Disease Control and Prevention", which has a "Vaccine and Vaccination" column under "Health Theme". The page is as follows:

The contents include the basic knowledge of vaccines, precautions for vaccination, and the "Report on Abnormal Reaction of Vaccination". Any adverse reaction of the vaccine will be recorded, and if there is any problem, it will be controlled and will not be allowed to develop.

At this point, parents should understand how important it is to vaccinate their children in time; I also know that the vaccine itself is a safe drug; In addition, there are also measures to avoid and deal with the adverse reactions of vaccines; If you have any questions you don’t understand, you can go to the hospital to consult a doctor, and you can also get information through the official website yourself.

Vaccination is the right of children and the responsibility of society. May the whole society realize the importance of vaccination and help children grow up healthily!

The article was produced by China, a popular science student, and was authorized to be published in the column "Learning Science with Xiaobian" of CCTV. Please indicate the source for reprinting.

Production: Wang Haina, the "Weiming" popular science team of Institute of Microbiology, China Academy of Sciences

Producer: computer network information center

[Observer Network Comprehensive Report] The China Manned Space Engineering Office was released on April 19, and it was decided by the General Mission Command of the Space Laboratory to launch the Tianzhou-1 cargo spacecraft at 19: 41 on April 20. On the afternoon of the 19th, the Long March 7 Tele-2 launch vehicle, which carried out the launch mission, began to inject propellant.

Tianzhou-1 is the first cargo ship independently developed by China. Because it only transports goods and doesn’t give them away, it is vividly called the "courier brother" in space. It adopts a two-compartment structure, with the smaller diameter being the propulsion compartment and the larger diameter being the cargo compartment. Its maximum diameter reaches 3.35 meters, the total length of the spacecraft is 10.6 meters, the load capacity reaches 6.5 tons, and it weighs 13.5 tons when it is fully loaded with goods. If fully loaded this time, it will probably become the most massive payload launched by China into space. It is even bigger than Tiangong-2 Space Laboratory, which is 10.4 meters long, 3.35 meters in diameter and 8.6 tons in mass.

Tianzhou-1 cargo spacecraft is waiting at the top of the Long March 7 rocket.

The main task of Tianzhou-1 is to "deliver goods" for Tiangong-2, and it will complete rendezvous and docking with Tiangong-2 Space Laboratory, implement on-orbit propellant replenishment, and break through and master key technologies such as on-orbit propellant replenishment. Tianzhou-1 is also equipped with more than 10 application loads such as non-Newtonian gravity experiments, and will carry out practical (trial) tests of space science and technology in orbit.

Among these goods, in addition to various supplies (including propellant) to maintain the operation of Tiangong-2, there are a large number of space experimental equipment and loads. Because the carrying capacity of the launch vehicle is fixed, if more goods are to be transported, it is necessary to reduce the "self-weight" as much as possible while ensuring the good performance of the spacecraft.

The "waist" of Tianzhou-1 is a connecting frame. "In order to make the parts firmly connected, the connection frame is generally thick." Wang Wei, chief designer of Tianzhou-1 cargo spacecraft, introduced that after many experiments and verification, the researchers designed the connection frame into a hollow form through numerical control machining simulation technology, and accurately removed the "fat" of the non-stressed part, leaving only the stressed part of the structure, which is equivalent to "liposuction" for Tianzhou-1, ensuring that the weight of the connection frame is reduced by about 50% on the premise of being strong enough.

The exterior of Tianzhou-1 is a wallboard structure. Although the design thickness is only about 3 mm, there is still room for "fat reduction" in the eyes of researchers. Because of the large wall area, even if only a thin layer like A4 paper is removed, the weight of the whole cabin will be reduced a lot. "Under the premise of not affecting the performance of the spacecraft, we have thinned the wallboard by strictly controlling the processing temperature, cutting speed and other parameters, so that the weight of Tianzhou-1 has been reduced by 30 kilograms." Wang Wei told reporters that the weight saved can transport several more devices.

In order to make more reasonable use of the cabin space and load more goods, the cargo hold of Tianzhou-1 was divided into many areas by its own "skeleton"-shelves. In the design of shelves, researchers chose light and high-strength materials. The "shelf panel" instrument board is made of aluminum alloy honeycomb board, and the "shelf frame" vertical beam is made of carbon fiber. "After many technological breakthroughs, the overall structure of Tianzhou No.1 has become light and strong, ensuring that the goods can be delivered to Tiangong No.2 intact." Wang Wei said.

So how does such a big "courier brother" ensure the safety of transporting goods?

"Tianzhou No.1 is big, but it has a delicate’ heart’." Zhang Jian, deputy director of the manned spacecraft general research office of the manned space general department of the Fifth Research Institute of China Aerospace Science and Technology Group, said that all the inner walls of the spacecraft are set as shelves, and a rectangular passage is left in the middle for astronauts to pass. Astronauts are in the shelf passage, and they can walk around, turn around and pick up and put goods at will.

In order to improve the carrying capacity of Tianzhou-1, an efficient carrying shelf design was adopted inside the spacecraft. Zhang Jian said that on the surface, these shelves are similar to ordinary storage compartments, but their details and configurations have been scientifically analyzed and demonstrated. The shelf adopts a beam-slab structure based on honeycomb panels and carbon fiber vertical beams, forming a large number of standard loading units with good force transfer effect.

Because there are many precision instruments and equipment and astronaut supplies in the materials transported by Tianzhou-1, the package loaded with materials must have protective function. Guo Junhui, the chief designer of cargo ship machinery, introduced that the newly developed high-tech cargo package is fresh and milky yellow in appearance, and the new antibacterial, moisture-proof and mildew-proof fabric can ensure that the goods can be stored in the package for one year. In addition, customized and serialized designs have been carried out for goods with different volumes and shapes.

"There are still intimate arrangements in the internal design of the package." Guo Junhui said that in order to avoid the direct connection between the goods and the shelf structure, there is also a newly developed foam or airbag bag that is fire-proof, moisture-proof and shock-proof. This "intimate" "soft packaging" design provides soft, high damping and distributed system support for the loading object.

"More than 100 packages of different sizes will ensure that the cargo materials of Tianzhou No.1 are delivered to Tiangong No.2 in good condition." Guo Junhui said.

Flight products such as Tianzhou-1 cargo spacecraft and Long March-7 remote launch vehicle, which were developed by China Aerospace Science and Technology Corporation, have successively entered the launch site since mid-February. According to the flight mission test and launch process, all the work in the technical area such as final assembly test was completed on April 17.

The combination of Long March 7 Yaoer carrier rocket and Tianzhou-1 cargo spacecraft is at Wenchang launch site in Hainan.

At 7: 30 on the 17th, the mobile launch platform carrying the combination of Long March 7 Remote 2 launch vehicle and Tianzhou 1 cargo spacecraft drove out of the final assembly test building, and after running smoothly for about 2.5 hours, it was transported vertically to the launch area. This means that the delivery task of "Tianzhou Express" is just around the corner.

The Tianzhou-1 launch mission conducted the last joint training in the whole region yesterday (18th). The results showed that the organization and command of each system were smooth, the technical status was correct, and the participating equipment was in good condition.

Organized and implemented by Wenchang Space Launch Site, this joint training is a comprehensive simulation exercise with the largest number, the most comprehensive and the closest to actual combat, besides "ignition launch", and it is also the last joint training before launch. At present, the five systems of launch site measurement, measurement and control, communication, meteorology and logistics are working simultaneously. This launch is a zero-window launch and faces great challenges.

Zhang Xueyu, commander of the launch site of Tianzhou-1 mission, said: Zero-window launch is the first time in Wenchang field. The main reason is that to accurately dock with Tiangong-2 after the cargo spacecraft is in orbit, it is necessary for all systems to coordinate, control and make precise decisions to ensure that the spacecraft can successfully enter orbit on time. At present, the state and parameters of all equipment are normal and have launch conditions.

Before Tianzhou No.1 leaves the factory

Verifying "Space Refueling" for the first time

Experts said that whether it is a space laboratory or a space station, it will "fall off" due to air resistance when operating in low-earth orbit. If the altitude cannot be maintained, its on-orbit life will be limited. This requires the rocket engine to start in time to maintain the orbital height, but the fuel it carries is limited. This puts forward the demand for the on-orbit propellant replenishment technology called "space refueling".

At present, only the United States and Russia have mastered the on-orbit propellant replenishment technology. One of the important missions of Tianzhou-1 is to verify this technology, which is also one of the key technologies to determine the smooth development of China’s future space station. To this end, Tiangong-2, which was launched into orbit in advance, installed a brand-new replenishment system, the principle of which is similar to the docking of oil pipes and oil guns, but the requirements for accuracy and sealing are very high.

Experts said that there is still a supplementary way to maintain orbit in the world, that is, after the cargo spacecraft docked with the space station, it used its own engine to "burn" excess fuel to raise the orbit of the space station. However, this orbit maintenance method has high requirements for the position of the spacecraft and the force on the interface, and it is not flexible enough.

Cargo ship with the strongest carrying capacity in active service

China plans to build a space station around 2022. Its initial scale includes a core module and two experimental modules. If astronauts want to stay in orbit for a long time, cargo ships are indispensable.

Experts say that cargo spacecraft evolved from manned spacecraft. The cargo spacecraft can transport propellant fuel, maintenance and replacement equipment, astronauts’ life and work supplies, space science experimental equipment and supplies, etc., and can also be used to adjust the orbital height of the space station. In the 1970s, the former Soviet Union and the United States began to develop space stations with large volume, long service life and wide applications.

At the beginning, both countries provided a small amount of supplies for the space station with manned spacecraft mixed with people and goods, and each manned spacecraft could only transport hundreds of kilograms of materials for the space station at a time, which could not meet the demand. On the basis of Soyuz manned spacecraft, the Soviet Union took the lead in developing the Progress cargo spacecraft, with a cargo hold of 6.6 cubic meters and a carrying capacity of 2.6 tons, which can be used for on-orbit propellant replenishment service. Europe’s cargo spacecraft is called automatic transfer aircraft, with a total length of 10 meters, a maximum diameter of 4.5 meters, a weight of about 10 tons, and a cargo capacity of 7 tons. It is the cargo spacecraft with the largest carrying capacity so far. From 2008 to 2014, five cargo spacecraft were launched, but construction has stopped at present.

The American "Dragon" spacecraft is 5.9 meters long, with a maximum diameter of 3.7 meters. The maximum mass of its transport load is 6 tons, and the maximum mass of its return load is 3 tons. It is also a master of transporting goods back to Earth in cargo spacecraft. In addition, the carrying capacity of American "Cygnus" and Japanese HTV cargo spacecraft is 2.7 tons and 6 tons respectively. Generally speaking, the carrying capacity of Tianzhou-1 is in the forefront, and its carrying capacity is the largest in the active cargo spacecraft.

The staff waved the national flag to refuel the Tianzhou-1 cargo spacecraft.

Reveal the secrets in the "Tianzhou-1" spacecraft