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Medical science

Treatment of articular cartilage injury with piezoelectric device

Osteoarthritis is a very common disease. As a result of trauma or aging, articular cartilage will be damaged, resulting in a direct impact on the bone, causing severe pain. At present, there is no effective cure for osteoarthritis. Recently, scientists have used a piezoelectric device to effectively improve the healing of knee cartilage defects in rabbits. The study has been published in the journal Science Translational Medicine.

The scientists woven poly (L-lactic acid) into fibers and made scaffolds and implanted them into the knee joints of rabbits with cartilage defects in the medial condyle of the femur. This material is not only biodegradable, but also generates electric current under pressure, which stimulates the formation and regeneration of articular cartilage. The rabbits recovered for a month after the operation, and then exercised on the treadmill for one to two months. The results showed that compared with the rabbits implanted with non-piezoelectric stents, the knee hyaline cartilage of rabbits implanted with this special stent regenerated well, the cartilage defects healed completely, and produced a large number of chondrocytes and collagen. The technique also needs to be tested in larger and older animals, and the animals need long-term observation after surgery to ensure that the regenerated cartilage is durable, the researchers said. This technique is expected to be used in the treatment of human osteoarthritis and other tissue injuries.

Material science

A new type of recyclable plastics based on sugars

Plastics are often made from petroleum-refined products, but oil resources are limited, so there is an urgent need to find other ways to make plastics. Recently, in a study published in the Journal of the American Chemical Society, researchers prepared a series of polymer plastics from sustainable materials. They not only have the properties of ordinary plastics, but also have higher degradability and recyclability.

The researchers selected derivatives of two kinds of sugars as raw materials for polymerization: isosorbitol and isomannitol, both of which are rigid rings and stereoisomers of each other. They found that the polymer plastics prepared from isosorbide alcohol have the toughness similar to that of ordinary plastics, and their strength is equivalent to that of nylon 6. The polymer plastics prepared with isomannitol as monomer not only have similar toughness and strength, but also show higher elasticity, that is, they have a higher ability to restore the original shape after deformation. These two types of plastics can also maintain their initial good mechanical properties after pulverization or heat treatment, so they can be recycled. In addition, if the mixture of isosorbide and isomannitol is used as the raw material of polymerization, the performance of polymer plastics can be controlled by controlling the ratio of the two raw materials, so as to meet the needs of different practical applications.

Last month, Israel launched the fourth dose of COVID-19 vaccine for high-risk and vulnerable people, and more than 500000 people have so far completed the fourth dose. According to the Israel Times, Reuters and other media reports, recently, Israel's Sheba Medical Center released its preliminary report on the trial of the fourth dose of COVID-19 vaccine (that is, the second enhanced injection). The results showed that the protective effect of the fourth dose of the vaccine against Omicron strain was not good.

It is reported that last month, the Sheba Medical Center conducted the trial among its employees. Among them, 154people received the fourth dose of Pfizer-BioNTech COVID-19 vaccine and observed the effect two weeks later, while the other 120 people received Modena COVID-19 vaccine and observed the effect one week later. All of these vaccinators had previously received three doses of Pfizer COVID-19 vaccine. The data showed that after the fourth dose of the vaccine, the antibody level in the vaccinated person was slightly higher than that after the third dose. However, the researchers believe that this antibody level is not enough to protect against Omicron strain infection; in addition, many people infected with Omicron strain have been vaccinated with four doses. But the researchers also pointed out that they have only conducted preliminary studies, the results have not yet been published, and that the vaccine has a good protective effect on strains such as Alpha and Delta. At present, more detailed data have not been disclosed.

Quantum computation

High-fidelity quantum gate operation is a necessary condition for the establishment of fault-tolerant quantum computing. How to test whether the fidelity of the fabricated quantum gate meets the requirements is the first problem to be solved to realize fault-tolerant quantum computing. The traditional quantum process tomography scheme increases exponentially with the increase of the size of the quantum gate. For the quality characterization of large-scale quantum gates and quantum circuits in the future, the traditional method is no longer practical.

Using the self-developed multi-parameter quantum precision measurement platform, the research team composed of Chinese University of Science and Technology, Fudan and Beijing University of Technology has improved the data processing algorithm of quantum gate test and can estimate the upper bound of distortion of quantum gate. They achieve the quantum gate test of the optimal sample complexity 1 / ∈, and the sample complexity required by this method does not increase with the increase of the quantum gate size. Using the optimal quantum gate test, the research team tested the two-bit CNOT gate and the three-bit Toffoligate respectively. On average, it only takes 1600 and 2600 measurements to check whether the fidelity is more than 99% and 97%, and the number of measurement bases used is only 20 and 32. For comparison, using quantum process tomography to characterize their distortion requires millions of measurements, as well as 324 and 4096 bases. The relevant results have been published in the physical Review KuaiBao. (news Network of China University of Science and Technology)

Behavior science

An action video game that can improve reading ability

The key to learning to read is to decode letters into sound. At the same time, we also need some basic skills such as attention control, working memory and cognitive flexibility, all of which can be improved through action video games. In a new study published in Natural Human behavior, scientists have developed an action video game for children based on the elements of traditional action video games.

The scientists recruited 150 Italian pupils aged 8 and 12, first tested their reading ability and attention, and, under the supervision of the school, divided them into two groups for six weeks. Two hours a week for game training: the first group played video games developed by the team, and the children needed to complete related tasks such as dodging, targeting and collecting resources in a limited time. The second group plays a programming game called Scratch, which requires planning, reasoning, and establishing logical structures to solve problems. After the training, the scientists tested two groups of children. The results showed that the first group had a seven-fold increase in attention control and a significant improvement in reading ability (reading speed and accuracy), while the second group had no improvement. In addition, the researchers assessed the children at 6, 12 and 18 months after training. Each time, the children in the first group performed better, which proved that the improvement was continuous.

Geoscience

The interior of the earth cools faster than expected.

4.5 billion years ago, the earth's surface was covered with hot magma and gradually cooled over milli