Effects of Composition and Melting Time on the Phase Separation of Poly(3-hydroxybutyrate)/Poly(propylene carbonate) Blend Thin Films

In this study, the effect of composition and melting time on the phase separation of poly­(3-hydroxybutyrate)/poly­(propylene carbonate) (PHB/PPC) blend thin films was investigated. Optical microscopy under phase contrast confirms the occurrence of phase separation of PHB/PPC blends at 190 °C. Polarized optical and scanning electron microscopies (POM and SEM) demonstrate that phase separation takes place along both horizontal and vertical film planes, which should be attributed to the two different interfaces and immiscible blends. A low PPC content (e.g. 30 wt %) results in the formation of compact PHB spherulites filling the whole space, whereas the noncrystallizable PPC spherical microdomains scatter in the PHB region, and their size shows a remarkable melting-time dependence. With the increasing PPC component and melting time, it is observed from POM that the separated PHB domains scattered in the continuous PPC phase, like the island structure. However, it can be revealed by SEM micrographs that the PHB thick domains are actually connected by its thin layer under the PPC layer. The real situation is, therefore, a large amount of PPC aggregates to the surface to form a network uplayer, whereas the PHB thick domains connected by its thin layer form a continuous PHB region, leading to a superimposed bilayer structure. There is also a small amount of PHB small domains scattered in the PHB phase. The PHB thick domains crystallize cooperatively with the PHB- or PHB-rich sublayer in a way just like the growth of pure PHB spherulites. This superimposed bilayer by interplay between phase separation and crystallization may provide availability to tailor the final structure and properties of crystalline/amorphous polymer blends

Effects of Composition and Melting Time on the Phase Separation of Poly(3-hydroxybutyrate)/Poly(propylene carbonate) Blend Thin Films

In this study, the effect of composition and melting time on the phase separation of poly­(3-hydroxybutyrate)/poly­(propylene carbonate) (PHB/PPC) blend thin films was investigated. Optical microscopy under phase contrast confirms the occurrence of phase separation of PHB/PPC blends at 190 °C. Polarized optical and scanning electron microscopies (POM and SEM) demonstrate that phase separation takes place along both horizontal and vertical film planes, which should be attributed to the two different interfaces and immiscible blends. A low PPC content (e.g. 30 wt %) results in the formation of compact PHB spherulites filling the whole space, whereas the noncrystallizable PPC spherical microdomains scatter in the PHB region, and their size shows a remarkable melting-time dependence. With the increasing PPC component and melting time, it is observed from POM that the separated PHB domains scattered in the continuous PPC phase, like the island structure. However, it can be revealed by SEM micrographs that the PHB thick domains are actually connected by its thin layer under the PPC layer. The real situation is, therefore, a large amount of PPC aggregates to the surface to form a network uplayer, whereas the PHB thick domains connected by its thin layer form a continuous PHB region, leading to a superimposed bilayer structure. There is also a small amount of PHB small domains scattered in the PHB phase. The PHB thick domains crystallize cooperatively with the PHB- or PHB-rich sublayer in a way just like the growth of pure PHB spherulites. This superimposed bilayer by interplay between phase separation and crystallization may provide availability to tailor the final structure and properties of crystalline/amorphous polymer blends

Effects of Composition and Melting Time on the Phase Separation of Poly(3-hydroxybutyrate)/Poly(propylene carbonate) Blend Thin Films

In this study, the effect of composition and melting time on the phase separation of poly­(3-hydroxybutyrate)/poly­(propylene carbonate) (PHB/PPC) blend thin films was investigated. Optical microscopy under phase contrast confirms the occurrence of phase separation of PHB/PPC blends at 190 °C. Polarized optical and scanning electron microscopies (POM and SEM) demonstrate that phase separation takes place along both horizontal and vertical film planes, which should be attributed to the two different interfaces and immiscible blends. A low PPC content (e.g. 30 wt %) results in the formation of compact PHB spherulites filling the whole space, whereas the noncrystallizable PPC spherical microdomains scatter in the PHB region, and their size shows a remarkable melting-time dependence. With the increasing PPC component and melting time, it is observed from POM that the separated PHB domains scattered in the continuous PPC phase, like the island structure. However, it can be revealed by SEM micrographs that the PHB thick domains are actually connected by its thin layer under the PPC layer. The real situation is, therefore, a large amount of PPC aggregates to the surface to form a network uplayer, whereas the PHB thick domains connected by its thin layer form a continuous PHB region, leading to a superimposed bilayer structure. There is also a small amount of PHB small domains scattered in the PHB phase. The PHB thick domains crystallize cooperatively with the PHB- or PHB-rich sublayer in a way just like the growth of pure PHB spherulites. This superimposed bilayer by interplay between phase separation and crystallization may provide availability to tailor the final structure and properties of crystalline/amorphous polymer blends

The number of up- and down-regulated miRNAs which target at Ca2+-CaM, Rho/ROCK, Ras/Raf/MEK/ERK and PKC pathways.

<p>The number of up- and down-regulated miRNAs which target at Ca2+-CaM, Rho/ROCK, Ras/Raf/MEK/ERK and PKC pathways.</p

The infection rate of HUVECs was determined by immunofluorescence staining of nucleoprotein (NP) protein.

<p>The immunofluorescence staining of normal cell, The infection rate of PR8 at MOI of 20, 30 and 40 were 32%, 46%, 51%, respectively at 12 h after infection and 50%, 62%, 68%, respectively at 24 h after infection. NP (green), nuclei (blue) were examined using fluorescent microscope.</p

List of the differential miRNAs and their target genes in HUVECs at 12 h and 24 h after CA07 infection.

<p>List of the differential miRNAs and their target genes in HUVECs at 12 h and 24 h after CA07 infection.</p

qRT-PCR measured the relative abundance of some miRNAs at 12 and 24 h after CA07 or PR8 infection.

<p>The relative abundance of each miRNA was determined in triplicate at different time points. *<i>P</i>< 0.05 versus non-infected cells, **<i>P</i>< 0.01 versus non-infected cells, ***<i>P</i>< 0.001 versus non-infected cells.</p

Effect of influenza A virus on transmonolayer electrical resistance (TER) and cytoskeleton in HUVECs.

<p>(A) HUVEC monolayers were infected with PR8 or CA07 at a MOI of 30, and the non-infected cells were used as control. TER values were monitored at 0 h, 2 h, 4 h, 6 h, 12 h, 24 h and 36 h after infection. *<i>P</i>< 0.05 versus non-infected cells, **<i>P</i>< 0.01 versus non-infected cells, ***<i>P</i>< 0.001 versus non-infected cells. (B) At 6, 12, 24 h after 30 MOI of PR8 or (C) CA07 infection, F-actin in HUVECs were examined using confocal microscopy with non-infected cells as control. F-actin cytoskeleton (red) and nuclei (blue) were examined using confocal microscopy. Scale bars represent 30um. PR8 and CA07 infection caused F-actin rearrangement in HUVECs. (D) Apoptosis of HUVECs were determined by TUNEL method via flow cytometry. The average fluorescence intensity was calculated by the Image software from three independent experiments. Three replicates were included. Data are expressed as means ± SEM, n = 3. The flow cytometry showed no significant apoptosis in HUVECs infected by PR8 or CA07.</p

List of the differential miRNAs and their target genes in HUVECs at 12 h and 24 h after PR8 infection.

<p>List of the differential miRNAs and their target genes in HUVECs at 12 h and 24 h after PR8 infection.</p

Analysis of miRNA profiles in HUVECs infected with influenza A virus.

<p>(A) At 12 h and 24 h after PR8 infection or CA07 infection, miRNA microarray was used to analyze the differential miRNAs between the miRNA profiles of the flu-infected and the non-infected cells. The up-regulated genes were shown in red and the down-regulated were shown in green. Three numbers of biological replicates were conducted. A1 and A2 indicated the miRNAs in non-infected cells at 12 h and 24 h, respectively; B1 and B2 indicated the miRNAs in PR8-infected HUVECs at 12 h and 24 h after infection, respectively; C1 and C2 indicated the miRNAs in CA07-infected HUVECs at 12 h and 24 h after infection, respectively. The degree of similarity between the replicates were demonstrated by Pearson's Correlation Coefficient, with the r values ranged from 0.77 to 0.99. (B) The numbers of coinciding miRNA that differentially expressed at the same time point in PR8- or CA07- infected- HUVECs is shown at the junction of two circles.</p