Coin an virtual currency exchange
a large part of the project parties are blocked out. In view of this situation, xt.com exchange has formulated a set of special service policies for the project party, such as lower money charging,
all-round service, and so on Together with Biyong, it created the world's first social transaction
In July 2017, Zhao CHANGPENG founded coin an. It took him six months to build it into the top three in global digital asset trading, with 6 million registered users. More than 30% of us digital currency players are users of coin an, which is now the largest virtual currency trading in the world
extended information:
value and repurchase mechanism:
1. Preferential dection of transaction fees of coin security platform
for users who participate in transactions on coin security platform, no matter what token they trade, if they hold enough BNB, the system will discount the transaction fees, According to the market value at that time, the equivalent amount of BNB is converted, and BNB is used to complete the payment of handling charges. Discount rate 50% 25% 12.5% 6.75% no discount
2. Buy back mechanism:
after the launch of the coin security platform, we will buy back 20% of the net profit of the current quarter of the coin security platform for BNB every quarter. The bought back BNB will be destroyed directly, and the buyback record will be published at the first time. Users can query through the blockchain browser to ensure transparency until the total number of BNB is 100 million
3. Decentralized trading "fuel"
in the future, BNB will also be the fuel of coin an's decentralized trading platform on the chain. BNB is needed when using coin an decentralized trading platform. It includes various functions such as dection of service charge and reward
if you are going to Hangzhou east bus station by bus, you can take a taxi to Wulin gate (civil aviation ticket office), and then take the airport bus to Xiaoshan airport
the airport bus takes about 40 minutes from Wulin gate to the airport
ABO blood group system
red cell blood group was discovered by K. Landsteiner of Austria in 1900. He cross mixed each person's red blood cells with other people's serum, and found that some blood agglutination occurred, while others did not. He believed that there was an antigen on the red blood cells and an antibody in the serum of those who agglutinated. If there is a specific relationship between antigen and antibody, agglutination will occur. If there is a antigen on red blood cells and anti-A antibody in serum, agglutination will occur. If the red blood cell lacks a certain antigen or the serum lacks the corresponding antibody, it will not agglutinate. According to this principle, he found the ABO blood group of human. Later, he put the red blood cells of different people into rabbits, and proced three kinds of immune antibodies in rabbit serum, which were called M antibody, n antibody and P antibody
with these three antibodies, three new antigens on red blood cells can be identified. These new antigens have nothing to do with ABO blood group. They are inherited independently and belong to another blood group system. And m, N and P are not the same system. The blood group genes controlling different blood group systems are on different chromosomes. Even on one chromosome, the gene loci of the two systems are far apart, not linked, so they are inherited independently
Rh blood group system
RH is the first two letters of rhesus Macacus. In 1940, when scientists such as Landsteiner did animal experiments, they found that Rh blood group antigen existed on the red blood cells of rhesus monkeys and most human bodies, so they named it. All human blood red blood cells with Rh antigen (also known as D antigen), known as RH positive. In this way, the four main blood groups of red blood cells a, B, O and ab were divided into RH positive and Rh negative. With the continuous study of Rh blood group, it is considered that Rh blood group system may be the most complex blood group in red blood cell blood group. The discovery of Rh blood group plays a very important role in guiding blood transfusion more scientifically, improving the experimental diagnosis of hemolytic disease of newborn and maintaining the health of mother and infant. According to the relevant information, Rh positive blood group accounts for about 99.7% of the Han nationality and most ethnic groups in China, and 90% of the indivial ethnic minorities. In some ethnic groups abroad, the proportion of RH positive blood group is about 85%, among which Rh negative blood group accounts for about 15% among European people.
in China, Rh negative blood group accounts for only three to four thousandths, and the proportion of Rh negative a, B, O and AB is 3:3:3:1
Rh negative people cannot accept RH positive blood because the antigen in RH positive blood will stimulate Rh negative people to proce RH antibody. If RH positive blood is infused again, hemolytic transfusion reaction can be inced. However, Rh positive people can accept the blood of Rh negative people
some blood group antibodies are incomplete antibodies and can not agglutinate with the corresponding antigen cells. There are antibodies in the serum, but it is not easy to find them. In 1945, anti human globulin test was applied to blood group test, which can check incomplete antibodies. Since then, many blood group antigens have been found. Every time a new antigen is found, it is necessary to determine the relationship between the antigen and the discovered blood group, so that a number of blood group systems are determined on human red blood cells. In addition, there are still some antigens, either because of their high frequency in the population, or because of their low frequency of distribution in the population, it is impossible to carry out genetic analysis on them. Before we know their genetic relationship, we call these antigens high frequency antigen and low frequency antigen respectively for the time being
Mn blood group system
another kind of blood group antigen on erythrocyte membrane is called Mn antigen, which is blood group glycoprotein A on erythrocyte membrane. It shows two zones in the SOS gel electrophoresis spectrum, namely PAS 1 and PAS 2, and blood group glycoprotein A is the two polymer of both. It is known that glycoprotein A is composed of 131 amino acids, and its primary structure has been determined (Fig. 2). The peptide chain of blood group glycoprotein A has a three segment structure. The amino acids 73-92 in the middle are hydrophobic and can cross the membrane lipid layer; The N-terminal peptide is located on the outer side of the membrane, which is related to the activity of blood group. There are 15 O-glycosidic sugar chains and one N-glycosidic sugar chain distributed on this peptide chain. The sialic acid in the sugar chain accounts for more than half of all sialic acids on the erythrocyte membrane; The C-terminal peptide is located in the inner side of the membrane and contains more acidic amino acids
Mn antigen is composed of M antigen and N antigen. If one sialic acid (N-acetylneuraminic acid) of M antigen is cut off by neuraminidase, it is n antigen. If another sialic acid is cut off, the antigenicity is completely lost. The antigenicity of Mn antigen is also related to the amino group in the peptide chain. If the amino group is protected by acetyl group, the antigenicity will be lost. With the discovery of S and s antigens, MNS blood group system was established
HLA blood group system
HLA blood group system is one of the most important human leukocyte antigens. Compared with red blood cell type, people have a later understanding of leukocyte antigen. The first human leukocyte antigen Mac was discovered by French scientist J. Dorset in 1958. HLA is the abbreviation of human leukocyte antigen. It has been found that there are more than 144 kinds of HLA antigens, which can be divided into seven series: A, B, C, D, Dr, DQ and DP7. Moreover, HLA also exists on the surface of other cells
HLA antigen is a glycoprotein (containing 9% sugar), and its molecular structure is very similar to immunoglobulin (Fig. 3). HLA consists of four peptide chains (including two light chains and two heavy chains), and two sugar chains are connected to the heavy chain. Part of HLA molecule is embedded in the double lipid layer of the cell membrane, and the part inserted into the membrane is equivalent to the Fc region of immunoglobulin IgG β- Microglobulin. Because of the similarity in molecular structure, HLA is closely related to the immune defense system
in addition, HLA and red blood cell blood group are controlled by genetic law, and the gene determining HLA type is on chromosome 6. Each person can obtain a set of chromosomes from his or her parents, so a person can find 5-10 types of leukocytes in the 5 series of a, B, C, D and DRS at the same time, so there are more than 100 million types of leukocytes. It is very difficult to find two HLA identical indivials in unrelated indivials. But there is always a quarter chance that HLA is identical or different between siblings. Therefore, HLA determination is the most powerful tool in forensic identification
P blood group system
P blood group system divides human blood groups into five phenotypes: P1, P2, P1, P2 and P. Among them, type P blood lacks antibodies against pp1p, which is a very rare blood type. The global population prevalence rate is less than 0.001%. Except for Japan and Sweden, there are only case reports in other countries< There are three kinds of proteins in erythrocyte membrane: glycoprotein, simple protein and membrane contractile protein. Some of the red blood cell antigens protrude on the surface of cells, like branches on the ground, such as ABH antigen; Some are embedded in the cell membrane, such as Rh antigen. The part of an antigen that specifically reacts with an antibody is called an antigenic determinant. The chemical composition of blood group antigenic determinants has been clear in some cases, but not in most cases. Some blood groups have soluble antigens in body fluids, which are called blood group substances. The substances of ABH and Lewis blood group isolated from human body are glycoproteins, that is, the side chains of some sugars are connected to the skeleton of peptide chain, and these sugars are the specific determinants. The specific determinants of ABH and Lewis blood group substances are very similar, but the specific determinants of indivial sugars or the same sugars on the sugar chain are different e to their different positions. For example, the antigenic specificity of a and B is different only if there is a different sugar in the sugar chain. The epitope A is an N-acetylgalactosamine at the end of the sugar chain, while the epitope B is a D-galactose at the end of the sugar chain
although the structure of ABH epitopes on red blood cells is the same as that in body fluid, the backbone of the two epitopes is different. The sugar chain on red blood cells is bound to acid through sphingosine, not protein, so the ABH antigen on red blood cells is glycolipid rather than glycoprotein
the antigenic determinants of Mn · P and I blood groups are also carbohydrates. The determinant of Rh antigen may be protein, because the activity of RH disappears immediately after the red blood cells are treated with thiohydrides, ureas and proteases
some blood group antibodies, such as anti IH, anti IA, anti IB and anti IP1, only react with cells with I antigen and another antigen, but not with cells with only one antigen. These antigens are complex antigens with two specificities on one molecule
Lewis blood group antigen is actually an antigen in plasma, and Lewis antigen on red blood cells is absorbed from plasma. I antigen is soluble in secretory fluid, but not in plasma. In addition, some blood groups have soluble antigens in plasma, but not in secretory fluid. BG antigen is actually the antigen of white blood cells, which may be shed from white blood cells to plasma, and then adsorbed from plasma to red blood cells, showing as the antigen of red blood cells. The antigens of Chido blood group and Rodger blood group are related to the fourth component of complement (C4) in plasma. There are three types of C4 by electrophoresis: fast swimming (f), fast swimming (f); Slow swimming (s); There are both fast and slow components (FS). There is Rodger antigen on red blood cells of people with only f component in plasma. In people with s component only, there is Chido antigen on red blood cells. Both Chido and Rodger antigens were found on the red blood cells of the patients with both components
the distribution of various blood group antigens on red blood cells is different, some are dense, some are loose. The number of antigens determines the strength of the antigen. Rabbit anti-A and anti-B sera labeled with radioiodine were used to examine human red blood cells. According to the radiation intensity of each cell, the number of antigens on each red blood cell could be calculated
the intensity of various blood group antigens is different at different stages of indivial development. The response of ABO and Lewis antigens to their corresponding antibodies in newborns is more delicate than that in alts. The red blood cells of less than 10 cm fetus can react with anti-P1 serum, but the intensity of reaction is weaker than that of alt red blood cells. The ability of absorbing anti-I of neonatal red blood cells is almost the same as that of alt red blood cells, but the intensity of agglutination reaction is far weaker than that of alt red blood cells. However, the agglutination with anti-I serum was stronger than that of alt red blood cells. Yta and XGA antigens were slightly weaker in neonatal red blood cells than in alt red blood cells, while antigens of RH, Kell, Duffy, JK, MNSs, Di and do systems were fully developed at birth. Chido blood group antigen can be detected in the plasma of newborn, but not in the red blood cells<
5 other related knowledge editor
blood generation
blood generation is very interesting, just like the relay run on the track and field field, the participants include the yolk sac, liver, spleen, kidney, lymph node, bone marrow, etc. make