Aldehyde-Sodium Alginate and Amino-Gelatin Preparation as Soft Tissue Adhesive

Sodium alginate and gelatin are both remarkable natural biomaterials; they all have been extensively applied in tissue engineering and other relative fields,due to their low price and good biocompatibility. In this paper,we oxidized sodium alginate with sodium periodate to convert 1,2-hydroxyl groups into aldehyde groups to get aldehyde-sodium alginate( A-SA). Gelatin was modified with ethylenediamine( ED) in the presence of water-soluble1-ethyl-3( 3-dimethylaminopropyl) carbodiimide( EDC) to introduce additional amino groups to get amino-gelatin. Upon mixing the A-SA and amino-gelatin aqueous solutions together,a gel rapidly formed based on the Schiff's base reaction between the aldehyde groups in A-SA and the amino groups in amino-gelatin.Fourier transform infrared spectroscopy( FTIR) analysis confirmed the characteristic peak of Schiff's base group in the hydrogel. The gelation time measure has confirmed the gelation time is dependent on the aldehyde group content in A-SA and amino group content in amino-gelatin. The fasted hydrogel formation takes place within 30 s. The entire test suggested that this gel could be a promising candidate as soft tissue adhesive.

Synthesis of a Ag/Ag Cl/PLA membrane under electron beam irradiation for the photocatalytic degradation of methylene blue and chloramphenicol

Polylactic acid(PLA)has been extensively applied in the fields of biology and renewable biodegradable materials because of its superior biodegradability.PLA has excellent potential as a renewable biodegradable adsorbent in wastewater treatment.However,its poor photocatalytic properties have hindered its practical application.In this study,polyvinylpyrrolidone(PVPP)or glutaraldehyde(GA)was utilized as an adhesive agent to prepare Ag/AgCl/PLA photocatalysts with highly efficient visible light photocatalysis on a PLA fabric by utilizing the electron beam irradiation method.The photocatalytic activities of the Ag/AgCl/PLA samples were examined under visible light irradiation to analyze the degradation of methylene blue(MB)and chloramphenicol(CPL).Our experimental results demonstrate that the nanomaterial Ag/AgCl was uniformly distributed on the PLA fiber surface;this can be attributed to the effects of the crosslinking PVPP or GA.Under electron beam irradiation,adding crosslinking PVPP(or GA)is beneficial to the loading of Ag/AgCl onto the PLA.For the composite Ag/AgCl/PLA,the degradation rate for MB was as high as 97% after 150 min of visible light irradiation.The addition of 4 mg/ml of Ag/AgCl solution resulted in the greatest photocatalytic activity for CPL,and we advanced the possible degradation pathways of CPL with the best sample.Additionally,the as-prepared composite Ag/Ag Cl/PLA exhibited favorable antibacterial activity against E.coli and S.aureus,with a bacterial removal rate of >77%.

Freeze-thaw bond properties of new-old concrete

Using composite cubic specimens of new-old concrete,the bond splitting tensile strength and failure mechanism for the interface of new-old concrete in saturating state were explored when exposed to freeze-thaw cycling. Specimens were experienced for 0,25,50,75,100 and 125 freezing cycles. The roughness and adhesion agent including cement paste,cement mortar and cement paste with 10 percent of UEA expanding agent were also investigated. The test results indicate that the bond splitting tensile strength decreases with increased numbers of freezing-and-thawing cycles. The roughness and adhesion agent have different effects on the bond strength.