Influence of molecular structure on the rheological properties and foamability of long chain branched polypropylene by “one-pot” reactive extrusion

2020 ◽  
pp. 0021955X2094310
Author(s):  
Yan Li ◽  
Zhen Yao ◽  
Shaolong Qiu ◽  
Changchun Zeng ◽  
Kun Cao
Keyword(s):  
Coupling Reaction ◽  
Reactive Extrusion ◽  
Expansion Ratio ◽  
Size Exclusion ◽  
One Pot ◽  
Synthesis Conditions ◽  
Twin Screw ◽  
Exclusion Chromatography ◽  
In Series ◽  
Long Chain

In this work, reactive twin screw extrusion was conducted to synthesize long chain branched polypropylenes (LCB-PPs) in a “one-pot” process in which dicumyl peroxide (DCP) initiated maleic anhydride (MAH) grafting onto the linear PP, and the concomitant coupling reaction between ethylene diamine (EDA) and MAH grafted polypropylene (PP-g-MAH) proceeded in series. Fourier transfer infrared spectroscopy (FTIR) on the prepared materials confirmed the occurrence of both reactions. A series of LCB-PPs were prepared using different amounts of EDA, MAH and DCP to study their effects and determine the optimal synthesis conditions. The prepared materials were characterized by size exclusion chromatography (SEC) and rheological analysis to ascertain the polymer microstructure. The foamability of the LCB-PPs by supercritical carbon dioxide (scCO2) foaming and foam morphology were investigated. The LCB-PPs were found to have vastly improved foamability and cellular morphology. Under optimal conditions, a foam expansion ratio of over 20 was achieved.

scholarly journals Very Small Apolipoprotein A-I-containing Particles from Human Plasma: Isolation and Quantification by High-Performance Size-Exclusion Chromatography

2000 ◽  
Vol 46 (2) ◽  
pp. 207-223 ◽  
Author(s):  
M Nazeem Nanjee ◽  
Eliot A Brinton
Keyword(s):  
Human Plasma ◽  
Size Exclusion Chromatography ◽  
High Performance ◽  
Hdl Cholesterol ◽  
Preparative Method ◽  
Size Exclusion ◽  
Crossed Immunoelectrophoresis ◽  
Exclusion Chromatography ◽  
In Series ◽  
And Function

Abstract Background: Very small apolipoprotein (apo) A-I-containing lipoprotein (Sm LpA-I) particles with pre-β electrophoretic mobility may play key roles as “nascent” and/or “senescent” HDL; however, methods for their isolation are difficult and often semiquantitative. Methods: We developed a preparative method for separating Sm LpA-I particles from human plasma by high-performance size-exclusion chromatography (HP-SEC), using two gel permeation columns (Superdex 200 and Superdex 75) in series and measuring apo A-I content in column fractions in 30 subjects with HDL-cholesterol (HDL-C) concentrations of 0.4–3.83 mmol/L. Results: Three major sizes of apo A-I-containing particles were detected: an ∼15-nm diameter (∼700 kDa) species; a 7.5–12 nm (100–450 kDa) species; and a 5.8–6.3 nm species (40–60 kDa, Sm LpA-I particles), containing 0.2–3%, 80–96%, and 2–15% of plasma total apo A-I, respectively. Two subjects with severe HDL deficiency had increased relative apo A-I content in Sm LpA-I: 25% and 37%, respectively. The percentage of apo A-I in Sm LpA-I correlated positively with fasting plasma triglyceride concentrations (r = 0.581; P <0.0005) and inversely with total apo A-I (r = −0.551; P <0.0013) and HDL-C concentrations (r = −0.532; P <0.0017), although the latter two relationships were largely attributable to extremely hypoalphalipoproteinemic subjects. The percentage of apo A-I in Sm LpA-I correlated with that in pre-β-migrating species by crossed immunoelectrophoresis (r = 0.98; P <0.0001; n = 24) and with that in the d >1.21 kg/L fraction by ultracentrifugation (r = 0.86; P <0.001; n = 20). Sm LpA-I particles, on average, appear to contain two apo A-I and four phospholipid molecules but little or no apo A-II, triglyceride, or cholesterol. Conclusions: We present a new HP-SEC method for size separation of native HDL particles from plasma, including Sm Lp A-I, which may play important roles in the metabolism of HDL and in its contribution(s) to protection against atherosclerosis. This method provides a basis for further studies of the structure and function of Sm Lp A-I.

scholarly journals Peptide barcoding for one-pot evaluation of sequence–function relationships of nanobodies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yusei Matsuzaki ◽  
Wataru Aoki ◽  
Takumi Miyazaki ◽  
Shunsuke Aburaya ◽  
Yuta Ohtani ◽  
...  
Keyword(s):  
Binding Affinity ◽  
Size Exclusion Chromatography ◽  
High Throughput ◽  
Size Exclusion ◽  
Targeted Proteomics ◽  
One Pot ◽  
Unique Peptide ◽  
Exclusion Chromatography ◽  
Protein Binders

AbstractOptimisation of protein binders relies on laborious screening processes. Investigation of sequence–function relationships of protein binders is particularly slow, since mutants are purified and evaluated individually. Here we developed peptide barcoding, a high-throughput approach for accurate investigation of sequence–function relationships of hundreds of protein binders at once. Our approach is based on combining the generation of a mutagenised nanobody library fused with unique peptide barcodes, the formation of nanobody–antigen complexes at different ratios, their fine fractionation by size-exclusion chromatography and quantification of peptide barcodes by targeted proteomics. Applying peptide barcoding to an anti-GFP nanobody as a model, we successfully identified residues important for the binding affinity of anti-GFP nanobody at once. Peptide barcoding discriminated subtle changes in KD at the order of nM to sub-nM. Therefore, peptide barcoding is a powerful tool for engineering protein binders, enabling reliable one-pot evaluation of sequence–function relationships.

scholarly journals Enzyme Catalyzed Copolymerization of Lignosulfonates for Hydrophobic Coatings

2021 ◽  
Vol 9 ◽  
Author(s):  
Sebastian A. Mayr ◽  
Nikolaus Schwaiger ◽  
Hedda K. Weber ◽  
Janez Kovač ◽  
Georg M. Guebitz ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Value Added ◽  
Coupling Reaction ◽  
Size Exclusion ◽  
Water Contact ◽  
Hydrophobic Coatings ◽  
Swelling Capacity ◽  
Exclusion Chromatography ◽  
Insoluble Polymers

Enzymatic polymerization of lignin can generate a variety of value-added products concomitantly replacing fossil-based resources. In line with this approach, a laccase from the thermophilic fungus Myceliophthora thermophila (MtL) was used to couple a hydrophobicity enhancing fluorophenol (FP) molecule, namely 4-[4-(trifluoromethyl)phenoxy]phenol (4,4-F3MPP), as a model substrate onto lignosulfonate (LS). During the coupling reaction changes in fluorescence, phenol content, viscosity and molecular weight (size exclusion chromatography; SEC) were monitored. The effects of enzymatic coupling of FP onto LS on hydrophobicity were investigated by the means of water contact angle (WCA) measurement and determination of swelling capacity. Full polymerization of LS resulting in the production of water-insoluble polymers was achieved at a pH of 7 and 33°C. Incorporation of 2% (w/v) of FP led to an increase in WCA by 59.2% while the swelling capacity showed a decrease by 216.8%. Further, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis indicated successful covalent coupling of the FP molecule onto LS by an emerging peak at 1,320 cm–1 in the FTIR spectrum and the evidence of Fluor in the XPS spectrum. This study shows the ability of laccase to mediate the tailoring of LS properties to produce functional polymers.

scholarly journals Size-exclusion liquid chromatography for effective purification of amphiphilic trinuclear gold(I) pyrazolate complex

2018 ◽  
Vol 14 (1-2) ◽  
pp. 133-137 ◽  
Author(s):  
Mohamad Azani Jalani ◽  
Leny Yuliati ◽  
Siew Ling Lee ◽  
Hendrik Oktendy Lintang
Keyword(s):  
Retention Time ◽  
Size Exclusion ◽  
Exclusion Principle ◽  
Chromatographic Technique ◽  
Exclusion Limit ◽  
Scanning Calorimetry ◽  
Purification Method ◽  
Visual Appearance ◽  
Exclusion Chromatography ◽  
In Series

Column gravity chromatography suffered from several drawbacks such as time-consuming and need a large amount of eluents. Herein we reported an efficient technique for effective separation of amphiphilic trinuclear gold(I) pyrazolate complex ([Au3Pz3]C10TEG) with high polarity based on size-exclusion principle of chromatographic technique. Based on the size-exclusion limit, [Au3Pz3]C10TEG having a larger size with molecular weight of 4011.39 Da (4030.40 Da when added Na+) was successfully eluted and collected firstly from its impurities after being recycled for 2 times. In the chromatogram for first cycle, an intense peak upon excitation at 220 nm for [Au3Pz3]C10TEG was observed at retention time of 58 mins, while small peaks due to the presence of impurities was observed in the range between 73 to 85 mins. In the second cycle, the impurities were flushed away before [Au3Pz3]C10TEG was successfully collected at retention time of 170 mins in the third cycle. The columns were a set of polystyrene/divinylbenzene (PS/DVB) JAIGEL-1H and -2.5H connected in series having exclusion limit of 1 X 103 and 2 X 104 in which chloroform was used as the eluent at flow rate of 3.5 mL min-1. As a result, the visual appearance of dark-yellowish [Au3Pz3]C10TEG was successfully purified to give pale-yellowish product. Moreover, differential scanning calorimetry thermogram showed that extra shoulder from impurities at 6.13 °C in the first endothermic peak of [Au3Pz3]C10TEG at 0.76 °C was completely removed. Hence, it can be concluded that size-exclusion chromatography can be used as an effective purification method with much more convenience and small consumption of solvents.

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