Autumn (September-October) is the harvest period of medium- and late-maturing apples, and it is also a critical period for orchard management. 1. Deeply change the soil, increase fat and grow trees. Deep plowing is suitable from mid-September to the beginning of October. You can use methods such as putting a tree in a nest (enlarging a hole), deep tumbling between plants, and deep turning in a garden. The depth is 60 to 80 cm, and attention should be paid to a lesser wound diameter of 1 cm. The above root. Deep plowing should be combined with mature soils. Generally, non-perishable twigs and hard stalks are layered into the bottom of deep plowing sluice, and a small amount of nitrogen fertilizer is applied, and then backfilled with topsoil. If farm fertilizer, green manure, compound fertilizer, and iron, zinc and other micro-fertilizers are to be applied together. When rooting deeply, roots should not be exposed to sunlight for a long time. After filling, the water should be poured in time to sink the soil. On the basis of deep turning, 0.3% to 0.5% urea, 0.3% potassium dihydrogen phosphate, 500 times photosynthetic fertilizer, 0.3% to 0.5% zinc sulfate, and 0.3% to 0.5% borax solution are used as foliar spray fertilizer. Prolong the functional period of leaves, improve photosynthetic performance, and correct the deficiency of fruit trees. After deciduous fruit trees, they must be poured with frozen water to ensure safe wintering. 2. Strengthen coloring management and improve fruit quality. Red Fuji and other varieties generally start from mid-September, and first pick off the shading leaves of the near fruit, and then pick off the leaves with no red leaves and the autumn shoots that are growing. The leaves within 5 cm around the top and periphery of the canopy and the leaves within 10 to 12 cm around the lower part of the canopy of the crown should also be removed to facilitate coloration. After 5-6 days after picking the leaves, the fruit was evenly distributed and the coloration was promoted. Bagging fruit is generally broken in 30 days before harvesting. In addition to single-layer bags, the paper bag is torn into an umbrella shape, and the paper bag is removed after about one week. In addition to the double-layer bags, the outer bag is first removed, and the inner bag is torn into an umbrella shape. After 5 to 7 days, the entire bag is removed. rip off. 3. Implement pruning with leaves. Autumn leaf pruning refers to the pruning of fruit trees from post-cultivation to defoliation. Its main task is to open branches and eliminate dense branches, improve tree illumination, and improve the quality of branches and leaves. When pulling branches, according to needs, the general branches are drawn at 70-80 degrees, and the auxiliary branches are pulled horizontally. Pull branches to be flat, straight, uniform, and avoid bowing. For saplings, focus on clearing one layer of densely crowded twigs, evacuating 2 or 3 each year, striving to adjust one layer of backbone sticks in 2 to 3 years, and mature trees to focus on the clearing of light-blocking layered auxiliary branches. The second floor has large lateral branches and large branch groups. If the tree is too high, it must be timely and happy to fall, and keep the tree height within 4 meters. 4. Do a good job of comprehensive prevention and control of pests and diseases. Entering in September, Bao Ye Bao Guo is the key to management of mid-late-maturing varieties. Generally, once every 15 to 20 days, 200 times the amount of Bordeaux mixture or 70% thiophanate-methyl 1000 times should be sprayed. 10 to 15 days before fruit picking, spraying with 25% carbendazim 500 times again to reduce the storage period disease. After the fruit trees defoliate, the orchards are cleared in time to remove the diseased fruit and insects, diseased and dead branches, fallen leaves and weeds, and scrape off the old cracked skin of the trunk, and burn them together. The tree trunk was painted white before freezing.
Bone Screw
Bone screws, also known as fracture fixation screws, are commonly used in clinical practice to fix orthopedic implants.
Bone screws are usually used to fix internal fractures or dislocations by directly screing into two different bone blocks or fixing an internal implant such as a bone plate to achieve fracture fixation, position the bone and promote its healing. Bone screws are used in a wide range of areas, including the shoulder, elbow, hip, knee, spine, etc. For example, pedicle screw systems are used for spinal fusion, and compression bone screws are commonly used for foot and ankle surgery or fixation of other fractures under pressure. Similar to traditional mechanical screws, the main structures of bone screws also include nail cap, nail body, and nail tip. Screws can be used to fix bone plates or bone fragments. When used for the former, they are called plate screws, and when used for the latter (to prevent the collapse of bone fragments), they are called positional screws. The latter can be inserted into the plate holes, and can be placed on the bone alone (also known as compression screws). Compression screws can be used to increase interfragment pressure.
(1) The screw cap
The screw cap has three main functions: the first is to optimize the force. The protruding cap makes the contact area between the screw and bone larger, increases the load area, optimizes the local force at the screw insertion site, and reduces the risk of bone rupture caused by excessive stress. The second is the positioning effect. The prominent cap makes the bone nail can only be screwed into a certain depth to prevent the whole bone nail from being screwed into the bone completely. The third function is to provide the position of force application by rotating the force groove at the cap to move the bone nail forward and drive it into the bone. Now, the force groove is mostly inner hexagonal, which does not require axial force to maintain the actuator in the center position and is suitable for a wider range of fractures.
(2) Screw the body
The size of the nail body determines the strength and fatigue resistance of the bone nail. The larger the diameter of the nail body, the stronger the strength will be, and the corresponding fatigue resistance will be better. In addition to the diameter of the nail body, the pitch and tooth depth of the screw body thread are also the key parameters of the nail body design. Different thread design has an important effect on the pressure and occlusal performance of the screw.
(3) Screw tip
Tapping is the process of phalangeal nail cutting thread in the bone. According to the shape of the nail tip, the bone nail can be divided into self-tapping nail and non-self-tapping nail. The nail tip of the self-tapping nail is sharper and can be directly screwed into the bone without pre-drilling. Usually, self-tapping screws are used for Cancellous bone, and the bone is compressed when the screw is inserted, so as to increase the bone density of the occlusal part locally and enhance the occlusal effect. However, when inserting screws in Cortical bone, the screw channel is generally pre-punched, and then the bone screw is screwed. Usually, the self-tapping screw is not directly used to prevent the bone screw from being stuck or damaged because the cortical bone is too hard.
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