Can the mechanical flap pass the security door of the electronics factory?

Security door is a detection device to detect whether people carry metal objects, also known as metal detection door. Metal detection safety doors are mainly used in airports, railway stations, large conferences and other public places with large crowds to check metal objects hidden in people, such as guns and controlled knives. A few high-end security doors in the market can give an alarm immediately when the inspected person passes through the security door and the metal carried by the person exceeds the preset parameter value according to the weight, quantity or shape, and display the position of the metal causing the alarm, so that the security personnel can find the metal items carried by the person in time. Most factory-specific security doors only identify whether metal objects are carried, locate and give an alarm to prevent products from being illegally taken out of the factory. The best security doors can detect items the size of paper clips.

Mechanical valves have insurmountable disadvantages, such as high thromboembolism rate, many anticoagulation-related complications and low long-term survival rate. As the second series of artificial heart valves, the research on biological valves has never stopped.

At present, the use of universal biological valves abroad accounts for about 30%, and Europe accounts for about 22%. In 1980s, due to the shortage of mechanical valves, about 70% of them were used in China. However, due to some problems in quality control and the increase of cases of defective biological valves after 1990s, mechanical valves are still the majority.

Prosthetic valves are divided into two categories according to the materials used: one is called mechanical valves made of artificial materials; The other is a biological valve made of all or part of biological tissues.

① Classification of mechanical valves: All mechanical valves can be divided into peripheral blood flow type (ball cage type and disc cage type) and central blood flow type (oblique disc type and Shuang Ye type) according to their blood flow patterns.

② Classification of biological valves: Biological valves can be divided into two types, heterogeneous valves and homograft valves. Among them, heterogeneous valves include porcine aortic valve and bovine pericardial valve; Homologous valves include fresh homograft aortic valve, autologous fascia lata valve and homograft dural valve.