(1) The relationship between root absorption of mineral elements and absorption of water. Mineral elements can only be absorbed by plants when dissolved in water. Water directly affects the absorption and transportation of mineral elements, but there is no proportional relationship between them, and each has relative independence.
(2) The roots of plants have the characteristic of selective absorption of mineral elements. The amount of salt ions absorbed by the roots is not proportional to the ions in the solution, and even the anions and cations of the same salt enter the plant body at different ratios, so that the composition and pH of the nutrient solution gradually change.
(3) Antagonism between single salt poison ions. Any plant, such as in a nutrient solution containing a single-salt, cannot grow, and is called a single salt poison. If a small amount of other salts are added thereto, the single salt poison can be eliminated, and the ions can eliminate each other. The phenomenon is called antagonism. Therefore, when determining and selecting a nutrient solution formula, the nutrient solution formula should be selected according to different types of characteristics.
The purpose of door and window sealing strip is divided into three categories: glass sealing strip (rubber strip), door leaf and door cover sealing strip and wool strip. The glass sealing strip is used for the sealing between glass and leaf and frame, the door leaf and door cover sealing strip is mainly used for the sealing between door panel and door frame, and the wool strip is mainly used for the sealing between frame and leaf. In the production and installation of plastic steel doors and windows, broken bridge aluminum doors and windows and wooden doors, sealing strip is an essential accessory.
The sealant strip plays an important role in waterproof, sealing and energy saving in plastic steel doors and windows, bridge broken aluminum doors and windows and wooden doors and windows, with sound insulation, dust prevention, antifreeze and warmth preservation. It must have strong tensile strength, good elasticity, and good temperature resistance and aging resistance. In order to ensure the fastening of the rubber strip and the profile, the section structure size of the rubber strip must match the profile of plastic steel doors and windows. Sealant strips are generally used for flat doors and windows, suspended windows and folding doors and windows. The main functions are dust prevention, insect prevention, waterproof, sound insulation, sealing, etc.
The installation position of the wool top is generally on the sliding window (door) leaf, the circumference of the frame leaf or the sealing bridge (wind block) to enhance the sealing between the frame and the leaf. Top specification is an important factor affecting the and watertight performance of push-pull doors and windows, and it is also an important factor affecting the switching force of doors and windows. If the wool top specification is too large or the vertical wool is too high, it will not only make assembly difficult, but also increase the moving resistance of doors and windows, especially the initial resistance when opening and the final positioning resistance when closing. If the specification is too small, or the height of the vertical top is not enough, it is easy to fall out of the groove, which greatly reduces the sealing performance of doors and windows.
There are two kinds of tops: silicified and non silicified. The top after silicified treatment has better effect in use. The appearance of the top with qualified quality is that the surface is straight, the bottom plate and vertical hair are smooth and free of bending, and there are no pits on the bottom plate, which meets the requirements of 0.2mm.
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