Objective To investigate the role of poly-lactic acid and agarose gelatin in promoting the functional recovery of the injured spinal cord. Methods Poly-lactic acid （PLA） or agarose was embedded in the space between ...Objective To investigate the role of poly-lactic acid and agarose gelatin in promoting the functional recovery of the injured spinal cord. Methods Poly-lactic acid （PLA） or agarose was embedded in the space between two stumps of the hemisectioned spinal cord. Immunohistochemistry was used to show astroglia proliferation and the infiltration of RhoA-positive cells. Locomotor activity recovery was evaluated by testing the function of hindlimbs. Results Astroglias and RhoA labeled non-neuronal cells accumulated in the area adjacent to the implant, while the number of RhoA-posirive cells was decreased dramatically in the absence of implant. Animals implanted with agarose gelatin recovered more quickly than those with PLA, concomitant with a higher survival rate of the neurons. Conclusion Both PLA and agarose gelatin benefited the recovery of spinal cord after injury by providing a scaffold for astroglia processes. Modulation of the rigidity, pore size and inner structure of PLA and agarose gelatin might make these biodegradable materials more effective in the regeneration of the central nervous system （CNS）.展开更多
Nowadays, recycled paper is broadly used due to environmental reasons. Furthermore, the addition of starch as a dry strength additive improves the properties of recycled paper. Poly-Lactic Acid (PLA), a product from b...Nowadays, recycled paper is broadly used due to environmental reasons. Furthermore, the addition of starch as a dry strength additive improves the properties of recycled paper. Poly-Lactic Acid (PLA), a product from bio-refinery process, has recently been shown to act as a promising strength additive that could be used in combination with starch to further improve the strength of paper. In this study, the use of PLA of three molecular weights (MW) in combination with four different starches was investigated. Three recycled pulps from different origins, with the kappa number of 27.9 to 66 were used. Paper handsheets were made, and selected paper properties were tested. The results indicate that handsheets properties were influenced by the MW of PLAs, the type of starch used, and the lignin content of the pulp. The paper handsheets made from lignin-rich pulp (pulp A, kappa number 66), combined with 0.1% medium MW PLA (PLA_1) and 0.9% cationic starch containing 0.43% N gave the highest improvement for tensile strength, wet tensile strength, air and water resistance. This result verifies that a higher kappa number pulp has better attraction to the hydrophobic PLA. Moreover, the higher charge cationic starch led to higher tensile strength due to the increase of affinity to the anionic fiber surface. Interestingly, results show that amphoteric starch is a promising substitute for high cationic charge starch when combined with the medium MW PLA to improve tensile strength of paper. This study demonstrated that a starch-PLA blend represents a promising approach in improving properties of recycled paper.展开更多
Improving structures involves comparing old and new designs on a key parameter.Calculating the percent change in performance is a method to assess.This paper proposes a cost-effective analogy by generating replicas of...Improving structures involves comparing old and new designs on a key parameter.Calculating the percent change in performance is a method to assess.This paper proposes a cost-effective analogy by generating replicas of additive manufactured aluminum alloy(Al Si10Mg)body-centered cubic lattice(BCC)based turbine blade(T106C)with the same in poly-lactic acid(PLA)material and their comparison in the context of percent change for natural frequencies.Initially,a cavity is created inside the turbine blade(hollow blade).Natural frequencies are obtained experimentally and numerically by incorporating BCC at 50%and 80%of the cavity length into the hollow blade for both materials.The cost of manufacturing the metal blades is 90%more than that of the PLA blades.The two material blade designs show a similar percentage variation,as the first-order mode enhancs more than 5%and the second-order mode more than 4%.To observe the behavior in another material,both blades are analyzed numerically with a nickel-based U-500 material,and the same result is achieved,describing that percent change between designs can be verified using the PLA material.展开更多
Three-dimensional porous poly-lactic acid(PLA) scaffold was fabricated using fused deposition modeling(FDM) method including 30%, 50% and 70% nominal porosity. Study of phases in initial polymeric material and printed...Three-dimensional porous poly-lactic acid(PLA) scaffold was fabricated using fused deposition modeling(FDM) method including 30%, 50% and 70% nominal porosity. Study of phases in initial polymeric material and printed scaffolds was done by X-ray diffraction(XRD), and no significant phase difference was observed due to the manufacturing process, and the poly-lactic acid retains its crystalline properties. The results of the mechanical properties evaluation by the compression test show that the mechanical properties of the scaffold have decreased significantly with increasing the porosity of scaffold. The microstructure of scaffolds were studied by scanning electron microscope(SEM), showing that the pores had a regular arrangement and their morphology changed with porosity change. The mechanical properties of the poly-lactic acid scaffolds printed using fused deposition modeling, can be adapted to the surrounding tissue, by porosity change.展开更多
Biodegradable polymer coatings are commonly used as protective barriers on magnesium(Mg) and its alloys.The properties of polymers,such as crystallinity and degradation properties,have a crucial impact on their corros...Biodegradable polymer coatings are commonly used as protective barriers on magnesium(Mg) and its alloys.The properties of polymers,such as crystallinity and degradation properties,have a crucial impact on their corrosion resistance.In this work,polyhydroxybutyrate(PHB) coatings are deposited on Mg sheets with a thickness similar to that of cardiovascular stents to assess the degradation behavior,and poly-lactic acid(PLA)-coated Mg is also investigated to compare the structure-propertyperformance relationship.The hydrogen evolution volume(HEV) of the PHB-coated sample decreases by 30% after immersion in artificial blood plasma(AP) for 7 days,whereas the PL A-coated sample shows an increase of 154%.The PHB coating also shows excellent durability at a constant voltage,compared to severe rupture of the PLA coating.The degradation behavior of the coated-Mg samples is evaluated in AP solution containing different concentrations of the bovine serum albumin(BSA).Corrosion is inhibited as the protein concentration increases.The degradation rates of the Mg,PLA-coated Mg,and PHBcoated Mg decrease by 65%,88%,and 75% for 5 g L^(-1)BSA,respectively.Our results reveal that higher crystallinity and less acidic degradation products give rise to better durability,while the acid self-catalytic effect leads to the failure of PLA.The protein-polymer interactions are determined and the empirical relationship of HEV is established.展开更多
文摘Objective To investigate the role of poly-lactic acid and agarose gelatin in promoting the functional recovery of the injured spinal cord. Methods Poly-lactic acid （PLA） or agarose was embedded in the space between two stumps of the hemisectioned spinal cord. Immunohistochemistry was used to show astroglia proliferation and the infiltration of RhoA-positive cells. Locomotor activity recovery was evaluated by testing the function of hindlimbs. Results Astroglias and RhoA labeled non-neuronal cells accumulated in the area adjacent to the implant, while the number of RhoA-posirive cells was decreased dramatically in the absence of implant. Animals implanted with agarose gelatin recovered more quickly than those with PLA, concomitant with a higher survival rate of the neurons. Conclusion Both PLA and agarose gelatin benefited the recovery of spinal cord after injury by providing a scaffold for astroglia processes. Modulation of the rigidity, pore size and inner structure of PLA and agarose gelatin might make these biodegradable materials more effective in the regeneration of the central nervous system （CNS）.
文摘Nowadays, recycled paper is broadly used due to environmental reasons. Furthermore, the addition of starch as a dry strength additive improves the properties of recycled paper. Poly-Lactic Acid (PLA), a product from bio-refinery process, has recently been shown to act as a promising strength additive that could be used in combination with starch to further improve the strength of paper. In this study, the use of PLA of three molecular weights (MW) in combination with four different starches was investigated. Three recycled pulps from different origins, with the kappa number of 27.9 to 66 were used. Paper handsheets were made, and selected paper properties were tested. The results indicate that handsheets properties were influenced by the MW of PLAs, the type of starch used, and the lignin content of the pulp. The paper handsheets made from lignin-rich pulp (pulp A, kappa number 66), combined with 0.1% medium MW PLA (PLA_1) and 0.9% cationic starch containing 0.43% N gave the highest improvement for tensile strength, wet tensile strength, air and water resistance. This result verifies that a higher kappa number pulp has better attraction to the hydrophobic PLA. Moreover, the higher charge cationic starch led to higher tensile strength due to the increase of affinity to the anionic fiber surface. Interestingly, results show that amphoteric starch is a promising substitute for high cationic charge starch when combined with the medium MW PLA to improve tensile strength of paper. This study demonstrated that a starch-PLA blend represents a promising approach in improving properties of recycled paper.
基金supported by the National Natural Science Foundation of China(No.12111540251)。
文摘Improving structures involves comparing old and new designs on a key parameter.Calculating the percent change in performance is a method to assess.This paper proposes a cost-effective analogy by generating replicas of additive manufactured aluminum alloy(Al Si10Mg)body-centered cubic lattice(BCC)based turbine blade(T106C)with the same in poly-lactic acid(PLA)material and their comparison in the context of percent change for natural frequencies.Initially,a cavity is created inside the turbine blade(hollow blade).Natural frequencies are obtained experimentally and numerically by incorporating BCC at 50%and 80%of the cavity length into the hollow blade for both materials.The cost of manufacturing the metal blades is 90%more than that of the PLA blades.The two material blade designs show a similar percentage variation,as the first-order mode enhancs more than 5%and the second-order mode more than 4%.To observe the behavior in another material,both blades are analyzed numerically with a nickel-based U-500 material,and the same result is achieved,describing that percent change between designs can be verified using the PLA material.
文摘Three-dimensional porous poly-lactic acid(PLA) scaffold was fabricated using fused deposition modeling(FDM) method including 30%, 50% and 70% nominal porosity. Study of phases in initial polymeric material and printed scaffolds was done by X-ray diffraction(XRD), and no significant phase difference was observed due to the manufacturing process, and the poly-lactic acid retains its crystalline properties. The results of the mechanical properties evaluation by the compression test show that the mechanical properties of the scaffold have decreased significantly with increasing the porosity of scaffold. The microstructure of scaffolds were studied by scanning electron microscope(SEM), showing that the pores had a regular arrangement and their morphology changed with porosity change. The mechanical properties of the poly-lactic acid scaffolds printed using fused deposition modeling, can be adapted to the surrounding tissue, by porosity change.
基金jointly supported by the National Natural Science Foundation of China(No.52171236)State Key Program of the National Natural Science Foundation of China(No.52231005)+5 种基金Open Research Fund of Jiangsu Key Laboratory for Advanced Metallic Materials,Southeast University(No.AMM2024A01)Suzhou Science and Technology Project(Nos.SJC2023005 and SZS2023023)City University of Hong Kong Donation Research Grants(Nos.DON-RMG 9229021 and 9220061)Hong Kong Innovation and Technology Fund(Nos.ITF GHP/212/22GD and CityU 440399)Hong Kong PDFS_RGC Postdoctoral Fellowship Scheme(Nos.PDFS2122-1S08 and CityU 9061014)Hong Kong HMRF(Health and Medical Research Fund)(Nos.2120972 and CityU 9211320)
文摘Biodegradable polymer coatings are commonly used as protective barriers on magnesium(Mg) and its alloys.The properties of polymers,such as crystallinity and degradation properties,have a crucial impact on their corrosion resistance.In this work,polyhydroxybutyrate(PHB) coatings are deposited on Mg sheets with a thickness similar to that of cardiovascular stents to assess the degradation behavior,and poly-lactic acid(PLA)-coated Mg is also investigated to compare the structure-propertyperformance relationship.The hydrogen evolution volume(HEV) of the PHB-coated sample decreases by 30% after immersion in artificial blood plasma(AP) for 7 days,whereas the PL A-coated sample shows an increase of 154%.The PHB coating also shows excellent durability at a constant voltage,compared to severe rupture of the PLA coating.The degradation behavior of the coated-Mg samples is evaluated in AP solution containing different concentrations of the bovine serum albumin(BSA).Corrosion is inhibited as the protein concentration increases.The degradation rates of the Mg,PLA-coated Mg,and PHBcoated Mg decrease by 65%,88%,and 75% for 5 g L^(-1)BSA,respectively.Our results reveal that higher crystallinity and less acidic degradation products give rise to better durability,while the acid self-catalytic effect leads to the failure of PLA.The protein-polymer interactions are determined and the empirical relationship of HEV is established.
