Electrocardiac signal is one of the most important signals which is used to trigger ventricular assist device (VAD), and the delay time of VAD assistance is very important to get a satisfied result. Proper delay will give VAD relatively enough time to assist, avoiding left heart failure caused by the collision of the heart and VAD during systolic phase. This becomes much more important when the left atrium drainage is insufficient. The aim of our study is to set up an equation to calculate the delay time by RR interval. We try to set up an equation about RR and R-Ao like: R-Ao = A x (RR)n + B(A and B are constant). RR represents the RR interval and R-Ao represents the duration of the period between the peak point of QRS and the point of aortic valve closing; First, calculate RR according to weighting average method, and then, calculate the anticipant R-Ao according to the before-mentioned equation. After adjustment, R-Ao will be used as assistance delay time. R-R interval was measured in 457 selected pediatric patients who were undergiong left heart catheterization and who did not have arrhythmias. From the ECG recording during catheterization, R-R interval was measured while R-Ao was obtained from aortic pressure wave chart; Plot graphs with R-Ao as dependent variable and (RR)n as independent variable; find out correlating model and calculate the arguments A and B of R-Ao = A x (RR)n + B. The results showed that the relation between (RR)1/3 and R-Ao is the most significant, the relation coefficient is 0.733, the regress coefficient is -0.182 (P < 0.001) and the interception is 1.070. This means that R-Ao = (-0.182) (RR) 1/3 + 1.070. The likelyhood degrees of different sections differ markedly. When heart rate is less than 120 beats per min. The relation argument is about 0.733 while 0.45 when heart rate is more than 120 beats per min, Therefore, we can use the equation R-Ao = (-0.182) (RR)1/3 + 1.070 to calculate R-Ao when heart rate is less than 120 beats per min.
Adolescent ; Algorithms ; Child ; Child, Preschool ; Counterpulsation ; methods ; Electrocardiography ; Heart ; physiology ; Heart-Assist Devices ; Humans ; Signal Processing, Computer-Assisted

The ethical dilemma in scientific research exists at all stages of the scientific research activities among medical graduate students， mainly involving conflicts of interest， clinical trials， animal experiments， and the relationship between teachers and students. If medical graduate students are in the ethical dilemma in scientific research for a long time， their research activities will be greatly affected. By discussing the connotation， evaluation tools， current situation， influencing factors， and improvement measures of ethical dilemmas in scientific research， this paper proposed some suggestions， such as comprehensively investigating the influencing factors of ethical dilemmas in scientific research， and formulating targeted improvement measures， with a view to helping medical graduate students identify and get rid of ethical dilemmas in scientific research， and promote the stability of research activities.

Enzymes are widely used in chemical and pharmaceutical industries because of their advantages of high efficiency and specificity. However， the shortcomings of the free enzymes， such as poor stability and difficulty in recycling， limit their application. Therefore， the immobilization and application of enzymes have become one of the research hotspots. The selection of the immobilization carriers is a critical step in the process of enzyme immobilization. Metal-organic frameworks（MOFs）， a kind of porous materials， are formed by the coordination of metal ions or metal clusters with organic ligands. As an emerging immobilization carrier， its advantages such as high porosity， strong stability， and surface modifiability make it ideal for immobilized enzyme carriers. By immobilizing the free enzyme on MOFs， the above mentioned deficiencies of the free enzymes can be effectively solved， which greatly broaden the applicable condition. Ligand fishing is a method to find receptor-specific ligands from complex components， which has the advantages of high efficiency， simple sample pretreatment and high specificity. The MOF-enzyme complex formed by enzyme immobilization can act as a "fishing rod" for ligand fishing， which can screen out the targets from the complex system of components. The complex chemical composition and various active ingredients of traditional Chinese medicine（TCM） make the ligand fishing technology to play a big role in the screening of enzyme inhibitors from TCM. And the screened enzyme inhibitors are expected to be further developed into the lead compounds with good efficacy and low adverse effects， so the immobilized enzymes of MOFs have a wide application in the screening of active ingredients from TCM. Based on this， this paper summarized the methods of immobilized enzymes of MOFs in recent years， analyzed the characteristics， advantages and disadvantages of each method， and summarized the laws of preparation conditions and mechanisms. Meanwhile， the application and future development of immobilized enzymes of MOFs in the field of enzyme inhibitor screening from TCM were also summarized and prospected， with a view to providing a reference for the development of natural ingredients and the modernization of TCM.