Agricultural Machinery Parts "Three Feelings" Appraisal Quality
Visual identification. Can identify the wear of the external parts, as well as the surface quality of the parts. Such as cracks in the cylinder block, cylinder head, gear and fatigue bearings on the surface of the fatigue, the injector, the exhaust valve after a serious burning blue or pitted annealing, clutch and brake friction material wear and burn, gear pair The bite marks, the degree of light leakage between the piston and cylinder liner, etc.
Auditory identification. Auditory identification can be tapped with a small hammer to gently check the metal parts of the inspection site, from the sound to determine whether the internal cracks, the connection is tight, generally close and sound parts sound crisp, defective voice murmur. This method can be used to identify whether the crankshaft, sidebars have cracks, the bearing alloy and the body of the joint, the rivet connection is solid and so on. In addition, the sound from the running gear set can also roughly determine the meshing condition.
Tactile identification. Tactile appraisal can be shaken by hand, and the gap size can be judged by sensation, and it is not necessary to measure with a measuring instrument. Such as the gap between the valve stem and the valve guide, the radial and axial clearance of the flow bearing, etc.
Polysaccharides are polymeric carbohydrate molecules composed of long chains of monosaccharide units bound together by glycosidic linkages, and on hydrolysis give the constituent monosaccharides or oligosaccharides. They range in structure from linear to highly branched. Examples include storage polysaccharides such as starch and glycogen, and structural polysaccharides such as cellulose and chitin.
Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure, these macromolecules can have distinct properties from their monosaccharide building blocks. They may be amorphous or even insoluble in water. When all the monosaccharides in a polysaccharide are the same type, the polysaccharide is called a homopolysaccharide or homoglycan, but when more than one type of monosaccharide is present they are called heteropolysaccharides or heteroglycans.
Natural saccharides are generally of simple carbohydrates called monosaccharides with general formula (CH2O)n where n is three or more. Examples of monosaccharides are glucose, fructose, and glyceraldehyde. Polysaccharides, meanwhile, have a general formula of Cx(H2O)y where x is usually a large number between 200 and 2500. When the repeating units in the polymer backbone are six-carbon monosaccharides, as is often the case, the general formula simplifies to (C6H10O5)n, where typically 40≤n≤3000.
As a rule of thumb, polysaccharides contain more than ten monosaccharide units, whereas oligosaccharides contain three to ten monosaccharide units; but the precise cutoff varies somewhat according to convention. Polysaccharides are an important class of biological polymers. Their function in living organisms is usually either structure- or storage-related. Starch (a polymer of glucose) is used as a storage polysaccharide in plants, being found in the form of both amylose and the branched amylopectin. In animals, the structurally similar glucose polymer is the more densely branched glycogen, sometimes called "animal starch". Glycogen's properties allow it to be metabolized more quickly, which suits the active lives of moving animals.
Cellulose and chitin are examples of structural polysaccharides. Cellulose is used in the cell walls of plants and other organisms, and is said to be the most abundant organic molecule on Earth.It has many uses such as a significant role in the paper and textile industries, and is used as a feedstock for the production of rayon (via the viscose process), cellulose acetate, celluloid, and nitrocellulose. Chitin has a similar structure, but has nitrogen-containing side branches, increasing its strength. It is found in arthropod exoskeletons and in the cell walls of some fungi. It also has multiple uses, including surgical threads. Polysaccharides also include callose or laminarin, chrysolaminarin, xylan, arabinoxylan, mannan, fucoidan and galactomannan.
Polysaccharide Series,Cordyceps Polysaccharide,Hericium Erinaceus Polysaccharide,Goji Polysaccharide
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