Cannulated screw is a common internal fixation device in orthopedic surgery.
Working process
During the operation, the Kirschner wire with the hole matching the hollow screw is first drilled into the bone of the fracture site, and then the hollow screw is screwed into the fracture site through the guidance of the Kirschner wire. Finally, the Kirschner wire is pulled out to complete the fixation of the fracture site. In many cases of fracture of the neck and femur, the healing cycle is long, and it usually takes about 30 months to remove the cannulated screws. At this point, the bone and the surface of the cannulated nail are closely connected and firmly connected in the nail path, which leads to defects easily generated by conventional nail removal methods, causing secondary injury at the fracture healing site and causing pain to the patient. Percutaneous cannulated screw internal fixation for femoral neck fractures has the advantages of small trauma, good healing, low rate of femoral head necrosis, and good stability.
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Mud farming
Mudworms, also known as loquats or true loaches, are small freshwater fish commonly found in various aquatic environments. These fish have distinct physical characteristics that set them apart from other species.
Physically, mudworms have a streamlined body with cylindrical pelvic fins that gradually slope backward. Their heads are pointed, and their eyes are relatively small, covered by a transparent membrane. The snout is angled forward, and its length is shorter than the area behind the eyes. They possess a lower, horseshoe-shaped mouth, along with five pairs of tentacles. The anal opening is small, and the caudal fin is rounded. A complete lateral line runs along their body, which helps them sense vibrations in the water. Their coloration is typically dark gray on the back and sides, with a lighter greyish-white belly. A prominent dark spot is often visible at the base of the tail, and their odd fins feature dense brown spots, while the even fins remain light gray without markings.
In terms of behavior, loaches are omnivorous, feeding on a wide variety of food sources. Juveniles under 5 cm primarily consume zooplankton, rotifers, and small crustaceans. As they grow, their diet expands to include insects, worms, algae, and plant fragments. Water temperature plays a significant role in their feeding activity, with the ideal range being 15°C to 30°C, and 25°C to 27°C being the most optimal for growth. When temperatures fall below 6°C or rise above 34°C, loaches become inactive and enter a dormant state. They tend to feed more actively in the evening but can adapt to daytime feeding in aquaculture settings.
Loaches grow rapidly, especially when provided with sufficient nutrition. A newly hatched fry is about 0.3 cm long, reaching 3 cm in one month, 6 cm in six months, and up to 13 cm by the end of their second year. Some individuals can grow as large as 20 cm and weigh around 100 grams.
Reproduction is highly efficient in loaches. They typically mature after two years and spawn between April and September, with peak spawning occurring between May and July. The ideal water temperature for spawning is 25°C to 26°C. Female loaches can lay thousands of eggs depending on their size, with larger females producing up to 1.8 million eggs. The eggs are oval, yellow, and slightly sticky, attaching to aquatic plants or other surfaces. After 2–3 days, the eggs hatch into fry.
Loaches are remarkably adaptable, thriving in various water conditions, including low-oxygen environments. They can breathe through their skin, gills, and even their intestines, allowing them to survive in poor water quality. This ability makes them resilient to environmental changes and even allows them to survive when dissolved oxygen levels drop to as low as 0.16 mg/L.
In addition to their ecological importance, loach meat is considered delicious and nutritious. It is believed to have therapeutic benefits for skin conditions, liver diseases, acne, and even impotence. Due to their popularity and economic value, loaches are widely farmed and sold in domestic markets, making them a key species in freshwater aquaculture.