Some small work problems and small conditions that occur in the laboratory, and learn the following ways to solve the troubles that often occur in experiments.
1. How to remove the thermometer that is glued by the rubber stopper?
When the thermometer or glass tube is stuck with the rubber plug or hose and it is difficult to remove, insert the tip of the small screwdriver or the blade into the gap between the thermometer (or glass tube) and the rubber plug (or hose) to form a gap. Drip a few drops of water, do this and extend around the thermometer (or glass tube) while gradually deepening and quickly remove it. You can also use a drill that just fits into the thermometer (or glass tube), put a little glycerin or water on it, put it in from one end of the thermometer, gently push it while pushing it, and when it is difficult to turn it, pull it out and put it on it. Lubricant, continue to rotate, and after repeated several times, the thermometer (or glass tube) can be taken out.
2. Remove special dirt from the instrument
When the solution is refluxed or the solution is concentrated, crystals are often deposited on the inner wall of the flask above the liquid surface, and the adhesion is firm, and not only the reaction cannot be continued, but also the discoloration is gradually degraded due to poor thermal stability. In this case, the flask can be gently shaken, and the internal solution is impregnated with crystals to dissolve. If the apparatus is not restricted in activity and the flask cannot be shaken, a cold wet cloth may be applied to the upper portion of the flask to dissolve the precipitated crystals when the solvent condenses down the wall.
3. The grinding of the glass instrument can not be opened.
1 Tap on the wood to gently tap the side of the grinding part to loosen it due to vibration. For the fixed reagent bottle, the grinding plug of the separatory funnel, etc., the plug and the bottle mouth of the instrument can be stuck at the corners of the test bench or the wooden table, and then the wood is lightly inclined at an angle of about 70° to the axis of the instrument. Tap gently and rotate the instrument intermittently. Repeat this operation several times to open the grind that is not severely fixed.
2 Heat some sticky grinding joints. It is inconvenient to knock or knock. The outer layer of the fixing part can be heated to expand and detach from the inner layer. For example, use a hot damp cloth to "hot pack" the sticky place, use a hair dryer or swim the flame to bake the grind, etc.
3 Infiltration Some grinding joints are firmly adhered due to drug erosion, or are valuable instruments with complicated structure. It is not suitable for tapping and heating. It can be opened after soaking in water or dilute hydrochloric acid for several hours. If the instrument is used urgently, an organic solvent with strong penetrability (such as benzene, ethyl acetate, petroleum ether and sodium dioctyl sulfosuccinate) may be added to the gap between the grinding ports to make it infiltrated into the stick. The fixed parts are thus separated from each other.
4. Quick drying instrument
When it is urgent to use a dry instrument in the experiment, and it is too late to dry by conventional methods, the inner wall of the instrument can be washed twice with a small amount of absolute ethanol, then rinsed once with a small amount of acetone to remove residual ethanol, and then blown with a hair dryer for a while. , the drying effect can be achieved.
5. Stabilize the flask in the water bath
When the material in the conical flask is cooled by cold water or ice bath, the flask is often floated due to the small amount of material and the buoyancy of the bath, which affects the cooling effect, and sometimes the accident that the flask is tilted into the bath may occur. If a circle of moderate length is used to make a circle smaller than the bottom diameter of the conical flask, the flask is placed in the flask and the flask is immersed in the bath. If the container used is a beaker, the circle can be placed over the beaker and the wire is hung on the mouth of the beaker to stabilize it and achieve sufficient cooling.
6. Dissolve the crystals precipitated on the inner wall of the flask
When the solution is refluxed or the solution is concentrated, crystals are often deposited on the inner wall of the flask above the liquid surface, and the adhesion is firm, and not only the reaction cannot be continued, but also the discoloration is gradually degraded due to poor thermal stability. In this case, the flask can be gently shaken, and the internal solution is impregnated with crystals to dissolve. If the apparatus is not restricted in activity and the flask cannot be shaken, a cold wet cloth may be applied to the upper portion of the flask to dissolve the precipitated crystals when the solvent condenses down the wall.
7. Clean up the spilled mercury: mercury-filled pressure gauges and mercury thermometers are commonly used in laboratories. If the operation is improper or the thermometer is damaged, a “spraying accident†will occur. Mercury vapor is extremely harmful to the human body, and it is necessary to promptly and thoroughly clean up the spilled mercury, and it must not be allowed to be lost. There are many cleaning methods, which can be selected according to different situations.
1 Absorb a small amount of mercury and use a common dropper to suck up the mercury beads one by one and collect them in a container. If the amount of mercury is large or spilled in the gap of the groove, the suction filter bottle can be connected to a 75° glass elbow through a rubber plug, and a “decompression aspirator†can be made to pass the mercury particles through the negative pressure. The glass tube is sucked into the filter bottle. The connection between the suction filter bottle and the pressure reducing pump can be slightly longer to prevent mercury from being drawn into the pump.
2 Adhere to the mercury spilled on the table top (or the ground). If it has been dispersed into fine particles, it can be adhered with tape paper, then immersed in water and brushed into the container with a brush. This method is simple and easy to perform.
3 Freezing: Mercury has a melting point of -38.87 °C. If the sprinkled mercury is covered with an appropriate amount of dry ice-acetone mixture, the mercury will be frozen into a solid and lose fluidity within a few seconds, which is easier to clean.
4 Conversion For traces of mercury that are scattered in the corners and difficult to retract by the above method, the areas where the mercury particles are lost can be covered with sulfur powder, and the mercury and sulfur are combined to form less toxic mercury sulfide, which is then removed.
8, eliminate emulsification
When the extraction and washing operation is carried out using a separatory funnel, the organic matter is washed with an alkali solution in particular, and after vigorous shaking, it tends to be difficult to separate due to the occurrence of emulsification without delamination. If the degree of emulsification is not serious, the separatory funnel can be slowly rotated in the horizontal direction and then left to stand for a while to eliminate the foam at the interface and promote delamination. If it is still not layered, add a proper amount of water, then shake it horizontally or place it overnight to separate the clear interface.
If the density of the solvent is close to that of water, it is easy to emulsify with water during extraction or washing. At this time, an appropriate amount of B can be added thereto to lower the density of the organic phase, thereby facilitating delamination.
For an emulsion formed by a slightly soluble ester of water and water, it can be stratified by adding a small amount of an inorganic salt such as sodium chloride or ammonium sulfate.
Paying more attention to the above experimental small steps can help you solve many big problems in experimental learning.
Treatment of Mycoplasma Diseases
It is mainly used for prevention and treatment of Mycoplasma suis pneumonia (also known as local epidemic pneumonia of pigs, commonly known as asthma of pigs), Mycoplasma gallisepticum infection (also known as chronic respiratory disease of chickens), contagious pleuropneumonia of sheep (also known as Mycoplasma ovis pneumonia), Mycoplasma bovis mastitis and arthritis, Mycoplasma ovis anomastia and arthritis, Mycoplasma suis serositis, arthritis, Mycoplasma avian synovitis, etc.
During the treatment, broad-spectrum antibiotics such as doxycycline, roxithromycin, azithromycin, tetracycline and erythromycin should be used, and the treatment should be carried out according to the drug instructions. It is used to treat animal Mycoplasma disease.
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A group of pleomorphic organisms between viruses and bacteria cause human, animal and plant diseases, called Mycoplasma disease. This disease is highly infectious and can make the disease spread rapidly. It is often infected with other laboratory animal diseases.
1. Mycoplasma spp is a kind of prokaryotic leptocyte, which can reproduce in the medium without leptocyte. Its size is between bacteria and virus, and its diameter is 80-300 μ m. It can pass through the sterilizing filter. It is polymorphous and can be spherical, rod-shaped, filamentous and other irregular shapes. It is gram negative.
2. Epidemiology klincherger et al. (1937) first isolated mycoplasma from the pneumonia foci of rats with bronchiectasis. Mycoplasma is the main pathogen of chronic respiratory diseases in rodent experimental animals, which is widely distributed in the production groups of rats and mice, and even more than Sendai virus and mouse pneumonia virus, The prevalence of mycoplasma is very serious in the experimental rat population in China. Lu Guozhen et al. (1989) reported that the infection rate of common BALB / c mice in the open environment is 40%, and that of clean BALB / c mice in the barrier system is 12.59%, which indicates that the barrier system can effectively control the invasion of the original microorganisms and reduce the infection rate of Mycoplasma. The natural hosts of mycoplasma are rats and mice, Different strains and ages of animals have different susceptibility to Mycoplasma. From cotton rat, hamster, guinea pig.
Mycoplasma was also isolated from rabbits and horses, which can cause arthritis and uveitis in immunized mice. Mycoplasma can often be isolated from the nasopharynx of wild rats. Therefore, it is very important to strengthen the feeding management of experimental rats and mice, and strictly prevent wild rats from entering. The infection of this disease is mainly caused by infected rats and Mycoplasma recessive carrier rats, which excrete toxin through respiratory tract secretion, contaminating feed, bedding material, etc In addition, the transportation of animals may also be an important way of transmission. Mycoplasma is an inherent pathogen in mice and rats. Uninfected animals and infected animals are easy to be infected when they are raised in the same cage. Because flat channel is the most vulnerable site to Mycoplasma natural infection, Therefore, the upper respiratory tract becomes the source of infection for other animals and animals' lower respiratory tract and reproductive tract. Mycoplasma is often isolated from vagina and Ziji, but it can not be detected from liver, spleen, kidney and heart. Due to the presence of Mycoplasma in genitalia, it often infects fetal rats and newborn rats, or causes contamination of caesarean section.
3. Clinical symptoms: the experimental animals were infected with mycoplasma, and the political diseases were mainly caused by Mycoplasma pneumoniae, Mycoplasma fulvum and Mycoplasma arthritis, especially Mycoplasma pneumoniae. Mycoplasma pneumoniae mainly caused pneumonia in rats and mice and female reproductive organ diseases (suppurative ovaritis, salpingitis and empyema).
4. Pathological changes Mycoplasma in the respiratory tract of rats caused by Mycoplasma generally does not show gross lesions, and animals infected by a small amount of Mycoplasma do not show or rarely show microscopic lesions. Mild infection is likely to be missed. Therefore, the organs of the respiratory tract and reproductive tract of animals should be made into sections for careful examination, If severe infection or epidemic occurs in mice, typical pathological damage caused by mycoplasma can be seen. For example, syncytial giant cells sometimes appear in nasal cavity and bronchiolitis epithelium of mice, which has certain characteristics and can confirm the existence of Mycoplasma. The pathological changes are mainly manifested as neutrophil infiltration in joints and surrounding tissues and mild proliferation of sea membrane cells, The sea membrane becomes hypertrophic, accompanied by a large number of lymphocytes, plasma cells and macrophages infiltration. The erosion of articular cartilage can lead to serious damage of joints. The pathological changes were as follows: (1) at the initial acute stage (lasting for about 2 weeks), neutrophil infiltration in the joint and surrounding tissues, and proliferation of synovium in the light disc; â‘¡ Acute and chronic inflammatory processes occurred together in the mixed period (3-10 weeks); â‘¢ In chronic stage (11-38 weeks or longer), meningococcal infection, monocyte infiltration and articular cartilage destruction occurred.
5. prevention and control of animals with too much density, high concentration of environment and infection of bacteria or viruses will increase the incidence rate of the rats. Therefore, prevention of this disease should raise the density of animal animal care and prevent the infection of other diseases.
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