ABSTRACT
BACKGROUND: The water molecules and biological macromolecules in human tissue may combine to form hydrate composite. Different types of macromolecules show different approaches to combine with water molecules. OBJECTIVE: To discuss the basic form of water molecules combined with biological macromolecules. METHODS: The theoretical hypothesis of texture composite hydration system was proposed. The relevant literatures were retrieved through the computer to discuss these issues. RESULTS AND CONCLUSION: According to the role of water in the hydrate composite, the composite ways can be divided into the following 4 groups. ①Surfaca composite: Hydrated membrane layers can form on the surface of globular protein or DNA molecules. The hydrated membrane layer shows that the speed of water molecular and hydrate density were reduced gradually from surface to inside. The hydrated layer makes the shape and physical state of the macromolecules stabilized, and it plays important role in forming of TCHS.②Swelling composite: As a result of the strong hydration of glycosaminoglycans, the hydrated proteoglycan often swells and shows high viscosity and hydrogel character. The hydrated proteoglycan play some mechanicalroles in connective tissue. For example, it can make the cartilage have a strong deformation-resistibility.③Hydrophobic composite: Hydr0phobic effect drives structural rearrangement, including the formation of bilayers (Bio-membrane). This hydrophilic-hydrophobic-hydrophilic "sandwich" structure is conducive to the self-stability in mechanics, combination with membrane protein and transmembrane transport. ④Slit composite: A lot of slit spaces with nano scale were existing inside and outside of the cells. Aqueous solution in the slit spaces shows some abnormal characters such as higher viscosity and lower ice point, because of the rearrangement of water molecules. Slit composite and surface composite have some universality, and it can be regarded the former as a special case of the latter. The classification way mentioned above has not any absolute connotations. However, the rational utilization of these hydration composite ways will be conducive to research the theory on textural composite hydrate system.
ABSTRACT
@#A new kind of medical sponges,ionic polyvinyl alcohol sponges(i-PVA sponges)were prepared by surface-grafting of acrylic acid onto acetal-PVA sponges.i-PVA sponges obtained show excellent hydrophilicity and water-absorption.The i-PVA sponges are three dimentional porous network.Because there are great amount of carboxyl and sodium carboxylate groups on PVA molecule chains,the speed of water absorption and water-absorptivity is >2.9mm/s and >15 times respectively.That is,in the case of the cataract-extraction,the polyion-modified sponges much more advantageous than any traditional nonionic polymer sponges.
ABSTRACT
@#Two types of catheter made of polymeric hydrogel were prepared and their mechanical properties were studied. The results showed PVA hydrogel catheter was prepared by repeated freezing-thawing cycles of PVA solution in mould. Another type of catheter (PVA-DMSO - hydrogel ) was prepared by cooling the PVA solution containing 10%wt DMSO in mould. The tensile strength (30～40MPa)and elongation(380 %～400%) of these two types of catheter were comparable with those of commercial PVC catheter and silicone rubber catheter. But the elastic modulus of PVA-DMSO hydrogel catheter was 10MPa,near to silicone rubber catheter and that of PVA hydrogel catheter was only 4MPa. γ-ray irradiation for sterile made 40%～50% loss of tensile strength for both catheter. Dipping in hibitane aqueous solution didn\'t affect mechanical properties.The obvious difference in mechanical properties was due to the difference in the orientation of PVA molecule chain and crystalline structure.
ABSTRACT
@#The tri-plate horizontal mould with nonrigid surgical sponge inserts was developed to establish an industrial system for shaping surgical sponge which is used for cataract operation. The conception on an insertion mechanism of nonrigid flat inserts was firstly suggested by us. The prototype horizontal moulds with tri plate have been designed and manufactured. The experiment results of hundred thousand of times injection shaping have proved that the conception of the design is rational. The structure of shafting mould for nonrigid flats has been confirmed. Present article discussed the design and working mechanism of the insertion in the horizontal injection mould.