It is easy to cause damage to the production of vegetables in the snow. It is recommended that you take corresponding measures to cope with snow and cold weather. First, clear the snow and strengthen the shed In the case of snowfall in the greenhouse, the quilt should be pulled open as soon as possible; the snow on the shed membrane should be cleaned in time to prevent the heavy load of the shed from damaging the shed and damaging the shed membrane due to the heavy snow and water absorption by the grass. When it snows, the old shed can be temporarily reinforced with bamboo, wood and iron (steel) sticks to enhance the load-bearing capacity of the shed. After snow, repair the damaged facilities in time and remove the waste film and brackets. Second, regulate the temperature to prevent frost damage Peppers, eggplants, tomatoes, etc. in the greenhouse are most vulnerable to snow damage and freezing damage during snow melting. Once the freezing damage occurs, the light output is reduced by 10% -20%, and the heavy output is reduced by more than 50% or absolutely. 1. On cloudy days, under the premise that the temperature of the shed can be guaranteed, the grasshoppers should be covered normally, and the dust, dirt and snow on the shed film should be removed with warm water to increase the sunshine in the shed and increase the shed temperature. As long as the temperature of the shed does not drop sharply after being uncovered, the grass should be uncovered every day to see the precious scattered light, and the time should be one hour later than the early morning when the cover is opened on a sunny day. 2. When snowing, cover the grass moth, and add a thin layer of moth or shed film on top of the original quilt or grass moth. It can not only protect the wind, but also prevent rain and snow from getting wet and freezing. Heat loss due to evaporation of water. Add grass curtains or corn stalks in front of the greenhouse, close the buffer room door tightly, and seal tightly and the front enclosure, to prevent the danger of cold wind entering. 3. Freshly planted melon and other seedling vegetables, set two membranes or set up small arch sheds in the greenhouse and cover with straw curtains, which can increase the temperature by 1 ° C-2 ° C. 4. Conditional parks can use heating equipment such as heaters, air conditioners, and radiators to increase the temperature, and add stoves or electric heaters, electric stoves, and combustion blocks to increase the temperature and protect seedlings in the greenhouse. 5. Use full-power plant growth lamps to supplement light. Under sufficient light, photosynthesis is good and the plants are robust, which can improve cold resistance against low temperatures, and at the same time increase the greenhouse temperature by about 2.5 ° C. 3. Water and fertilizer management to improve stress resistance 1. During snowfall, if it is not severely dry, do not water the vegetables to avoid lowering the ground temperature. If the plant is deficient in water, the sunny weather just after the cold current should be selected, and drip irrigation under film or small water under film should be used. Strictly control watering in cold weather, and prevent cultivating cold. The method of using shallow middle ploughing to break up wet soil to control water transpiration, raise ground temperature, and promote root absorption capacity. 2. The photosynthetic capacity of the leaves in snowy days is reduced, and foliar fertilizer can be appropriately sprayed to supplement nutrients. It is recommended to use biological amino acids or biological potassium bacterial fertilizer and humic acid to supplement nutrition. 3. Foliar spraying of biostimulant to improve cold resistance of plants. Foliar fertilizer can be sprayed and alginic acid can be added at the same time, such as 20ml of Amez, 15ml of Azeb sprayed with 15 liters of water, or 20ml of Amez, 10ml of Tubaokang sprayed with 15L of water, can increase The sugar content and hardness of the mesophyll can alleviate the degree of frost damage. 4. Ventilation and dehumidification to prevent diseases The photosynthesis of plants is reduced in snowy days, and the resistance to stress is reduced. At the same time, low temperature and low light increase the humidity in the shed, which is likely to cause diseases. Reasonable ventilation and dehumidification should be used to control the occurrence of diseases. 1. Due to the slow evaporation of water in the snow shed, it is forbidden to perform operations such as cutting branches, thinning flowers, spraying drugs, picking fruits, etc., so as to avoid causing germ infection caused by wounds and causing diseases. 2. On cloudy and snowy days, the respiratory consumption of vegetables is greater than photosynthesis, and a large amount of harmful gases such as carbon dioxide will accumulate in the greenhouse. Therefore, when the weather is more than 3 days in the cloudy and snowy day, it is necessary to let out the air for 1 hour when the snow stops at noon. moisture. 3. After the snow suddenly clears, the weakly growing vegetables are suddenly irradiated by strong light, and the plants will quickly lose water, causing the leaves to wither, fall, fall, or die. For fruits and vegetables, when the local temperature is below 10 ° C, the growth and absorption of the root system basically stop. After snow, the weather is fine. If the grass is removed immediately, the temperature of the shed will increase rapidly, the light will increase, and the plant will transpiration a lot of water, and the root system will be unable to meet the transpiration of the leaves under the condition of very weak water absorption. If the measures are not taken in time, it will The leaves form permanent withering that is difficult to recover and eventually lead to plant death. In order to prevent this from happening, be careful not to pull it full when you uncover the grass, and perform a "back curtain" to prevent sudden strong light exposure after a long period of low temperature and weak light, resulting in physiological wilting. 4. Vegetable mildew, sclerotinia, black spot disease, late blight and other diseases are very easy to occur under low temperature and high humidity. When controlling these diseases, it is advisable to use aerosols such as chlorothalonil and sclerocrine, which is conducive to uniform application Without increasing the indoor air humidity. Disclaimer: Some articles on this website are transferred from the Internet. If you have third party legal rights, please inform this website to deal with them. phone
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.
Bone Screw,Cancellous Screw,screws in bone,Cortical Screw Jiangsu Aomed Ortho Medical Technology Co.,Ltd , https://www.medthofixation.com