Centrifuge, according to the size of the workload, mainly from the two aspects of speed and capacity. The following is a detailed introduction to the common sense of the centrifuge:
(1) Rotating speed: Centrifuge is divided into low speed centrifuge (<1 0000 rpm/min), high speed centrifuge (1 0000 rpm/min 30,000 rpm/min), ultra high speed centrifuge (>30000 rpm) according to the maximum speed. /min), each centrifuge has a rated maximum speed. The maximum speed refers to the speed under no-load conditions, but the maximum speed varies depending on the type of rotor and the quality of the sample. For example, a centrifuge rated at 16,000 rpm/min indicates that the rotor rotates 16,000 times per minute at no load, and after the sample is added, the speed must be less than 16000 rpm/min. The rotor is different, the maximum speed is different (one imported centrifuge can be equipped with multiple rotors), the horizontal rotor can reach 1 5000 rpm/min, but the angle rotor can reach 14000 rpm/min. The specific difference should be consulted in detail. The sales personnel and the relevant technical personnel of the production plant should be cautious in the selection of the speed. The maximum speed of the selected centrifuge should be higher than the target speed. Such as: target rotational speed is 16000 rpm / mIn, centrifuge the selected maximum speed must be higher than 16000 rpm / min.
(2) Temperature: Some samples (such as proteins, cells, etc.) will be destroyed under high temperature conditions. This is to choose a refrigerated centrifuge. The refrigerated centrifuge has a rated temperature range. The heat generated by the centrifuge at high speed is balanced with the refrigeration system of the centrifuge at a certain temperature (the sample for general freeze centrifugation needs to be kept at 3 ° C ~ 8 ° C), and the specific amount can be related to the rotor, such as a centrifuge The rated temperature range is -10 ° C ~ 60 ° C, the horizontal rotor can be rotated to about 3 ° C when installed, if the angle rotor may only be about 7 ° C. This should also be consulted in detail about the product sales staff and the relevant technical personnel of the production plant.
(3) Capacity: How many sample tubes need to be centrifuged each time 7 How much capacity is needed for each sample tube 7 These factors determine the total capacity of a centrifuge, simply the total volume of the centrifuge = the capacity of each centrifuge tube × centrifugation The number of tubes, the total capacity and the size of the workload are matched.
(4) Rotor: The rotor of the centrifuge is mainly divided into two types: horizontal rotor: the running blue is in a horizontal state during operation, at right angles to the rotating shaft, and the sample concentrates the sediment on the bottom of the centrifuge tube: the angle rotor: the centrifugal container is fixed with the rotating shaft At the angle, the sample concentrates the sediment on the bottom of the centrifuge tube and the side wall near the bottom. If you want the separated sample to be concentrated at the bottom of the centrifuge tube, select the horizontal rotor. If you want the sample to concentrate on the bottom of the centrifuge tube and the side wall near the bottom, select the angle rotor.
There are also special tests or special samples that require special rotors such as large-capacity baskets (used for blood stations), ELISA plate rotors, slide rotors, PCR rotors, test tube rotors, and capillary rotors. The rotor has a fixed size, which is combined with the capacity of the centrifuge, such as the 36 × 5 ml angle rotor, which determines the type of rotor and determines the capacity of the centrifuge, so the choice of the rotor is very important.
(5) Control system: High-end centrifuges use microcomputer control systems. These control systems not only ensure the safe operation of the centrifuge but also automatically complete the task. Now many centrifuges have a better humanized control system. For example: rotor identification function, safety lock function, fault prompt function, acceleration and deceleration curves, and so on. In addition to the above points, pay attention to some details and necessary accessories. The main component of the centrifuge is the motor. The motor is divided into a carbon brush motor and a carbonless brush motor. The former has been eliminated. Most of the current centrifuges are brushless motors, and some motors also have a brake function. Refrigerated centrifuges also differ in terms of refrigeration, and now environmentally friendly technologies are of course fluorine-free refrigeration. In addition to this, consider the noise problem and try to choose a quieter centrifuge to maintain a comfortable experimental environment. Be cautious in terms of accessories. Some experiments use special centrifuge tubes (centrifugal toxic samples or need to be super
For high-speed centrifugation of the sample), such a centrifuge tube must be equipped with a corresponding sleeve for safety. There are also some special sample containers (irregular vials, blood bags, etc.). These details and accessories must be carefully considered when selecting a centrifuge, otherwise normal operation will not be possible.
Coarse grain usually refers to rice, wheat, corn, soybean and potato five crops other than the grain and bean crops. The main are: sorghum, millet, buckwheat (sweet buckwheat, buckwheat), oats (naked oats), barley, millet, barley millet, barley millet, grain amaranth and beans (kidney beans), mung beans, adzuki beans (adzuki beans, adzuki beans), broad beans, peas, cowpea, lentils (soldier beans), black beans and so on. It is characterized by short growing period, small planting area, special planting area, low yield, and generally contain rich nutrients. The ancient Chinese medicine book "Huangdi Neijing" records that "five grains are for raising, five fruits are for helping, five livestock are for benefiting, and five vegetables are for filling". Some trace elements, such as iron, magnesium, zinc and selenium, are more abundant in coarse grains than in refined grains. The value of these trace elements to human health is considerable. Coarse grains are also richer in potassium, calcium, vitamin E, folic acid and bioflavonoids than refined grains.
Whole Grains are rich in nutrients. Oats, for example, are rich in protein; Millet is rich in tryptophan and carotene. Beans are high in quality protein; Sorghum is rich in fatty acids and iron; Tubers contain carotene and vitamin C. In addition, coarse grain still has the effect of reducing weight. Such as corn also contains a lot of magnesium, magnesium can strengthen intestinal wall peristalsis, promote the excretion of body waste, is very beneficial to weight loss.
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