Abstract: A ventilation and noise reduction housing and assembly, a ventilation and moisture retention apparatus, a breathing mask assembly and a breathing support device are provided. The ventilation and noise reduction housing includes a respiratory passage segment, one end thereof is a ventilation and noise reduction housing connection end, and the other end thereof is a respiratory tube communication end. The wall of the respiratory passage segment includes a mounting wall segment, that is provided with exhaust vents and a supporting protrusion structure protruding from the outer surface of the mounting wall segment, the supporting protrusion structure is used for supporting a ventilation and noise reduction core of a ventilation and noise reduction unit provided on the mounting wall segment, such that a ventilation gap is at least partially maintained between the ventilation and noise reduction core and the outer surface of the mounting wall segment.

Abstract: The present invention discloses a cellulose derivative shown as formula (I), which is obtained as follows: the hydroxyl at position 6 of microcrystalline cellulose is protected with triphenylchloromethane, and then reacted with acyl chloride or isocyanate. After the protection of the hydroxyl at positions 2 and 3 of microcrystalline cellulose, triphenylmethyl is removed under acidic conditions to expose the hydroxyl at position 6. Finally, the hydroxyl at position 6 is chiral derivatized with amino acid acyl chloride or polypeptide acyl chloride, to obtain a micro chiral regulation cellulose derivative. The micro chiral regulation cellulose derivative thus obtained is coated onto the surface of a silica gel support, to form a chiral stationary phase, which is filled in a stainless steel column to form a chiral column for the separation of various different types of chiral compounds. The preparation method of the present invention is not only efficient and convenient, but also safe and reliable.