Photochemistry of lignocellulosic materials and related compounds

The primary photochemical processes of lignin-rich high-yield thermomechanical pulp (TMP) have been investigated with a view to understanding and ultimately preventing the yellowing (photoreversion) of such paper upon exposure to sunlight. This would enable their use in longer-life paper products and therefore represent large raw material and cost savings to the pulp and paper manufacturer. [Continues.

Photochemistry of lignocellulosic materials and related compounds

The primary photochemical processes of lignin-rich high-yield thermomechanical pulp (TMP) have been investigated with a view to understanding and ultimately preventing the yellowing (photoreversion) of such paper upon exposure to sunlight. This would enable their use in longer-life paper products and therefore represent large raw material and cost savings to the pulp and paper manufacturer. [Continues.

Inimer Mediated Synthesis of Hyperbranched Polyglycerol via Self-Condensing Ring-Opening Polymerization

A series of hyperbranched polyglycerols (HPGs) have been synthesized using glycol as an initiator in the presence of potassium counterion ([K⁺]₀/[−OH]₀ = 0.75) and employing batch monomer addition (BMA) to obtain insight into the kinetics of the polymerization. The first-order time–conversion plots show that the polymerization is fast up to ∼200 min, and the rate decreases substantially with increasing reaction time. Size exclusion chromatography of the HPGs during the polymerization indicates the presence of two living species in the reaction: a large fraction that grows into oligomers (<3000 g/mol) and becomes stabilized at higher conversion and a small fraction, growing faster and able to sustain a larger degree of polymerization (>140 000 g/mol). ¹³C NMR of the oligomer HPG shows signals corresponding to epoxy ring headgroup at 45.1 and 52.0 ppm and confirms the formation of epoxy anion, an inimer, via intermolecular proton transfer from glycidol. Self-condensing ring-opening polymerization of epoxy inimer produces ill-defined hyperbranched inimer–oligomers in high yield along with a small fraction of high molecular weight HPG that propagates without significant transfer to glycidol. The differential scanning calorimetry analysis shows the HPG exhibited two distinct <i>T</i>_gs (<−50 and >−20 °C) indicating the oligomer and high molecular weight fractions are immiscible, which is attributed to conformational constraint of two different types of branching. A mechanism of the formation of HPGs is proposed involving inimer-mediated equilibrium between oligomers and high molecular weight HPGs. The slow monomer addition (SMA) protocol was employed to reveal the existence of inimers during the reaction, supporting the proposed mechanism

All-Acrylic Multigraft Copolymers: Effect of Side Chain Molecular Weight and Volume Fraction on Mechanical Behavior

We present the synthesis of poly­(<i>n</i>-butyl acrylate)-<i>g</i>-poly­(methyl methacrylate) (P<i>n</i>BA-<i>g</i>-PMMA) multigraft copolymers via a grafting-through (macromonomer) approach. The synthesis was performed using two controlled polymerization techniques. The PMMA macromonomer was obtained by high-vacuum anionic polymerization followed by the copolymerization of <i>n</i>-butyl acrylate and PMMA macromonomer using reversible addition–fragmentation chain transfer (RAFT) polymerization to yield the desired all-acrylic multigraft structures. The P<i>n</i>BA-<i>g</i>-PMMA multigraft structures exhibit randomly spaced branch points with various PMMA contents, ranging from 15 to 40 vol %, allowing an investigation into how physical properties vary with differences in the number of branch points and molecular weight of grafted side chains. The determination of molecular weight and polydispersity indices of both the PMMA macromonomer and the graft copolymers was carried out using size exclusion chromatography with triple detection, and the structural characteristics of both the macromonomer and P<i>n</i>BA-<i>g</i>-PMMA graft materials were characterized by ¹H and ¹³C NMR. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was employed for monitoring the macromonomer synthesis. Thermal characteristics of the materials were analyzed using differential scanning calorimetry and thermogravimetric analysis. The mechanical performance of the graft materials was characterized by rheology and dynamic mechanical analysis, revealing that samples with PMMA content of 25–40 vol % exhibit superior elastomeric properties as compared to materials containing short PMMA side chains or <25 vol % PMMA. Lastly, atomic force microscopy showed a varying degree of microphase separation between the glassy and rubbery components that is strongly dependent on PMMA side chain molecular weight

Additional file 2: of Exosomes from endothelial progenitor cells improve outcomes of the lipopolysaccharide-induced acute lung injury

The RNA sequencing results showed genes were significantly altered by overexpression of miR-126-5p in SAECs. Human small airway epithelial cells (SAECs) were transfected with either control miRNA or miR-126-5p mimic for 48 h, and total RNA was isolated for RNA sequencing analysis. Genes significantly altered by miR-126-5p were listed. (XLSX 433 kb

Additional file 1: of Exosomes from endothelial progenitor cells improve outcomes of the lipopolysaccharide-induced acute lung injury

The RNA sequencing results showed genes were significantly altered by overexpression of miR-126-3p in SAECs. Human small airway epithelial cells (SAECs) were transfected with either control miRNA or miR-126-3p mimic for 48 h, and total RNA was isolated for RNA sequencing analysis. Genes significantly altered by miR-126-3p were listed. (XLSX 366 kb

Anionic Polymerization of Oxadiazole-Containing 2‑Vinylpyridine by Precisely Tuning Nucleophilicity and the Polyelectrolyte Characteristics of the Resulting Polymers

Anionic polymerization is one of the most powerful techniques for preparation of well-defined polymers. However, this well-known and widely employed polymerization technique encounters major limitations for the polymerization of functional monomers containing heteroatoms. This work presents the anionic polymerization of 2-phenyl-5-(6-vinylpyridin-3-yl)-1,3,4-oxadiazole (VPyOzP), a heteroatom monomer that contains both oxadiazole and pyridine substituents within the same pendant group, using various initiating systems based on diphenyl­methyl potassium (DPM-K) and triphenyl­methyl potassium (TPM-K). Remarkably, well-defined poly­(2-phenyl-5-(6-vinylpyridin-3-yl)-1,3,4-oxadiazole) (PVPyOzP) polymers having predicted molecular weights (MW) ranging from 2200 to 21 100 g/mol and polydispersity indices (PDI) ranging from 1.11 to 1.15 were prepared with TPM-K, without any additional additives, at −78 °C. The effect of temperature on the polymerization of PVPyOzP was also studied at −78, −45, 0, and 25 °C, and it was observed that increasing the polymerization temperature produced materials with unpredictable MW’s and broader molecular weight distributions. Furthermore, the nucleophilicity of PVPyOzP was investigated through copolymerization with methyl methacrylate and acrylonitrile, where only living poly­(methyl methacrylate) (PMMA) prepared by DPM-K/VPPy and in the absence of additives such as lithium chloride (LiCl) and diethyl zinc (ZnEt₂) could be used to produce the well-defined block copolymer of PMMA-<i>b</i>-PVPyOzP. It was also demonstrated by sequential monomer addition that the nucleophilicity of living PVPyOzP is located between that of living PMMA and polyacrylonitrile (PAN). The pyridine moiety of the pendant group also allowed for quaternization and produced PQVPyOzP homopolymer using methyl iodide (CH₃I) and bis­(trifluoro­methyl­sulfonyl)­amide [Tf₂N^–]. The resulting charged polymer and counterion complexes were manipulated and investigated for potential use as membranes for carbon dioxide (CO₂) capture

MOESM1 of A Stromal Cell-Derived Factor 1Îą Analogue Improves Endothelial Cell Function in Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome

A Stromal Cell-Derived Factor 1Îą Analogue Improves Endothelial Cell Function in Lipopolysaccharide-Induced Acute Respiratory Distress Syndrom

High Temperature Thermoplastic Elastomers Synthesized by Living Anionic Polymerization in Hydrocarbon Solvent at Room Temperature

We present the synthesis and characterization of a new class of high temperature thermoplastic elastomers composed of polybenzofulvene–polyisoprene–polybenzofulvene (FIF) triblock copolymers. All copolymers were prepared by living anionic polymerization in benzene at room temperature. Homopolymerization and effects of additives on the glass transition temperature (<i>T</i>_g) of polybenzofulvene (PBF) were also investigated. Among all triblock copolymers studied, FIF with 14 vol % of PBF exhibited a maximum stress of 14.3 ± 1.3 MPa and strain at break of 1390 ± 66% from tensile tests. The stress–strain curves of FIF-10 and 14 were analyzed by a statistical molecular approach using a nonaffine tube model to estimate the thermoplastic elastomer behavior. Dynamic mechanical analysis showed that the softening temperature of PBF in FIF was 145 °C, much higher than that of thermoplastic elastomers with polystyrene hard blocks. Microphase separation of FIF triblock copolymers was observed by small-angle X-ray scattering, even though long-range order was not achieved under the annealing conditions employed. In addition, the microphase separation of the resulting triblock copolymers was examined by atomic force microscopy