Number-average Molecular Weight Research Articles

Structural characteristics, immune-activating mechanisms in vitro, and immunomodulatory effects in vivo of the exopolysaccharide EPS53 from Streptococcus thermophilus XJ53

Our previous investigations have successfully identified the repeating structural units of EPS53, an exopolysaccharide derived from Streptococcus thermophilus XJ53 fermented milk, and substantiated its potential immunomodulatory properties. The present study further elucidated the structural characteristics of EPS53 and investigated the underlying mechanisms governing its in vitro immunoreactivity as well as its in vivo immunoreactivity. The results obtained from multi-detector high performance gel filtration chromatography revealed that EPS53 adopted a rigid rod conformation in aqueous solution, with the weight-average molecular weight of 1464 kDa, the number-average molecular weight of 694 kDa, and the polydispersity index of 2.11. Congo red experiment confirmed the absence of a triple helix conformation. Scanning electron microscopy showed that EPS53 displayed a three-dimensional fibrous structure covered with flakes. The in vitro findings indicated that EPS53 enhanced phagocytosis ability, reactive oxygen species (ROS) production, and cytokine levels of macrophages via the TLR4-mediated NF-κB/MAPK signaling pathways as confirmed by immunofluorescence staining experiments, inhibition blocking experiments, and Western blot assay. Additionally, the in vivo experiments demonstrated that EPS53 significantly increased macrophage and neutrophil number while enhancing NO and ROS levels in zebrafish larvae; thus, providing further evidence for the immunomodulatory efficacy of EPS53.

Synthesis of Propellant Grade HHTPB by Hydrogenation of HTPB using Pd-activated charcoal as catalyst

To derive more performance from the conventional composite propellant based on Hydroxyl-terminated polybutadiene (HTPB) and ammonium perchlorate (AP), it is envisaged to hydrogenate HTPB, which increases the H/C (hydrogen to carbon ratio) of the base polymer. This paper attempts to describe the partial hydrogenation of HTPB using a catalytic method that uses palladium supported by activated charcoal as a catalyst and HTPB polymer as a precursor. HTPB has a hydroxyl value of 41.0 mg KOH/g with a number average molecular weight (Mn) of 6150, polydispersity (PD) of 2.25 was used as a precursor. Iso-propyl alcohol (IPA) and toluene were used as a solvent media to disperse the HTPB polymer during hydrogenation. The estimate revealed an increase in specific impulse (ISP) up to 1.2 sec with ∼37 % hydrogenated HTPB. Partial hydrogenation is only attempted to retain other process capabilities essential for realizing a defect-free solid propellant grain with good structural integrity. In contrast, others attempt to reach near saturation. A reactor capacity of 100 ml, operating at 60 bar pressure, was used to synthesize HHTPB, and the extent of hydrogenation was controlled based on the numerous experiments varying the reactor parameters like operating temperature, operating pressure, and solvent-to-polymer ratio for a given catalyst concentration. Detailed characterization of the end product by FTIR, 1H-NMR and 13C-NMR to reveal the degree of hydrogenation along with generic polymer characteristics. The measured hydroxyl value of HHTPB is comparable with HTPB; however, a marginal increase in molecular weight and polydispersity was noticed at 37 % conversion, wherein other researchers found a loss in -OH value. Thermogravimetry analysis revealed no significant change in the gasification rate. A slight increase in the H/C ratio and calorific value was observed for HHTPB compared to HTPB. Despite the increase in viscosity of HHTPB, the increase in the vinyl-type functional distribution of HHTPB aids for better process-ability during propellant processing. However, the propellant formulation should be optimized with the help of plasticizers, solid loading, etc., to achieve the required properties.

Interpenetrating polymer networks of polyurethane and polytriazole: Effect of the composition and number average molecular weight of glycidyl azide polymer on the mechanical properties and morphology

AbstractOn account of some special advantages of interpenetrating polymer networks (IPNs), the preparation of IPNs with excellent properties may be a promising way to strengthen the polyurethanes (PUs) and toughen the glycidyl azide polymer (GAP) based polytriazoles (PTAs). This work provides the effect of composition and number average molecular weight (Mn) of GAP on the mechanical properties and morphology of full‐IPNs. A series of IPNs based on the crosslinked Ace‐terminated GAP (Ace‐GAP) as polytriazole phase and crosslinked hydroxy‐terminated liquid fluorinated polymer (HTLF‐1500) as polyurethane phase (namely, GAP‐HTLF‐X full‐IPNs) were successfully fabricated via in situ polymerization without any catalysts at 80°C by azide–alkynyl click chemistry and hydroxyl‐isocyanate urethane reaction. These IPNs were characterized using attenuated total reflectance/Fourier‐transform infrared spectroscopy (ATR/FTIR), uniaxial tensile testing, swelling measurement, and scanning electron microscopy (SEM). The tensile strength of GAP‐HTLF full‐IPNs gradually increased by increasing the weight ratio of Ace‐GAP, but the breaking elongation dramatically decreased compared with elongation at break of HTLF polyurethane. In addition, a small Mn of GAP is beneficial in enhancing the tensile strength, elongation at break and toughness of the IPNs. However, a small Mn of GAP corresponds to increased difficulty of preparing GAP‐HTLF full‐IPNs. GAP1k‐HTLF full‐IPN was not successfully prepared. When the Mn of GAP was 2000 g/mol, the GAP2k‐HTLF‐80 full‐IPN exhibited prominent mechanical performance with a tensile strength of 83.1 MPa, elongation at break of 28.5% and fracture energy of 99.1 kJ/m3. Swelling measurement showed that when the weight ratio of GAP with larger Mn (5, 3, and 2 k) increased to more than 70%, the molecular interpenetration existed in the IPNs, demonstrating the presence of additional physical crosslinks and entanglement for full‐IPNs. SEM studies revealed that highly formed interpenetration and few microphase separations can be observed on the fracture surface of the IPNs with optimal mechanical properties. Combined with the results of mechanical properties, swelling measurement, and SEM studies, the degree of molecular interpenetration and microphase separation were beneficial to improve the mechanical properties of elastomers. This work can provide a certain guiding significance for the preparation of IPN with excellent properties.

Analytical data of Acacia nilotica var. Nilotica gum

This study aimed to characterize the exudate gum from Acacia nilotica var. nilotica in Sudan and compare its physicochemical properties to Acacia seyal var. seyal and Acacia senegal var. senegal (gum Arabic). Samples were collected from six different states in Sudan over three seasons. The gum had a moisture content of 10.50%, ash content of 1.86%, pH value of 5.19, specific optical rotation of +94.70, intrinsic viscosity of 10.44 cm3 g-1, nitrogen content of 0.024%, protein content of 0.16%, acid equivalent weight of 1907.82, and total uronic acid content of 10.18%. Sugar content analysis revealed arabinose (41.20%), galactose (17.43%), and rhamnose (10.68%). Potassium was the predominant cation, followed by calcium, magnesium, sodium, lead, and iron. Acacia nilotica was classified as part of the Gummeferae series and exhibited a positive specific optical rotation. The Number average molecular weight (Mn) was estimated using osmometric measurements and gel permeation chromatography. The gum had a higher molecular weight and lower intrinsic viscosity compared to gum Arabic, suggesting a spheroidal shape of molecule. Amino acid analysis showed similarities with gum Arabic, with hydroxyproline and serine as principal amino acids. Variations in cationic composition were attributed to differences in soil type among collection locations. KEY WORDS: Physicochemical characterization, Acacia senegal var. senegal gum, Acacia seyal var. seyal gum, Acacia nilotica var. nilotica gum, gammiferae Bull. Chem. Soc. Ethiop. 2024, 38(4), 839-852. DOI: https://dx.doi.org/10.4314/bcse.v38i4.2

Biobased high barrier copolyesters derived from furandicarboxylic acid and citric acid

Biobased feedstocks developed from renewable resources play a crucial role in polymers. Dimethyl octahydro-2,5-pentalenediol (MeOPD) with excellent thermal stability and rigidity is a biobased bicyclic diol derived from citric acid. In this work, MeOPD was first reacted with dimethyl carbonate (DMC) to form oligo (dimethyl octahydro-2,5-pentalenediol carbonate) (OMC). Subsequently, a series of poly(butylene-co-dimethyl octahydro-2,5-pentalenediol furanoate-co-carbonate) (PBMFC) polyesters with MeOPD units ranging from 5 to 31 mol% were synthesized via melt polycondensation from OMC, dimethyl furan-2,5-dicarboxylate (DMFD) and 1,4-butanediol (BDO). Due to the low reactivity of MeOPD, its actual content in copolymer is much lower than that in the feed, and as the MeOPD content rises, the number-average molecular weight of PBMFCs drops from 25,200 g/mol of PBMFC5 to 12,800 g/mol of PBMFC31. Despite the presence of MC units weakens thermal stability, PBMFCs still maintain good thermal stability, evidenced by Td,5% ranging from 294-325 °C in N2 and from 295-339 °C in air. The mechanical properties are also satisfactory, exhibiting tensile modulus ≥ 500 MPa, tensile strength ≥ 23 MPa, and elongation at break ≥ 150 %. Compared to PET, PBMFCs demonstrate commendable gas barrier properties, with CO2 and O2 barrier capability being 4.7–11.0 times and 2.0–3.6 times that of PET, respectively. All results indicate that PBMFCs can serve as a renewable potential material for packaging application.

Rapid fractionation of pseudo-lignin with high yield by chemical and mechanochemical methods

The formation of pseudo-lignin (PL) is important to promote the refining of lignocellulosic biomass, but there is a problem of low yield of PL. In this study, we developed two chemical and mechanochemical approaches to efficiently extract PL using dilute acid combined with deep eutectic solvent (DES) and double ball-milling and enzymatic hydrolysis (DBEH), respectively. After dilute acid pretreatment at 220 °C for 4 h, due to the degradation of polysaccharides, a large amount of PL was formed and adhered to cellulose. Subsequently, PL was extracted using DES and DBEH, with extraction rates of 30.77% and 30.16%, respectively. There was a little difference in the structure of PL extracted by DES and DBEH, but gel permeation chromatography showed a significant difference in molecular weight between them, with the former having a weight-average molecular weight (Mw) of 1233 g/mol, and a number-average molecular weight (Mn) of 674 g/mol, and the latter a Mw of 5720 g/mol, and a Mn of 3210 g/mol. However, the polydispersity index obtained by both methods was narrow, ranging from 1.78 to 1.83. Moreover, FTIR and 2D-HSQC have provided the PL formation mechanisms. During pretreatment, holocellulose was hydrolyzed to form monosaccharides, which were further degraded to produce intermediates 5-hydroxymethylfurfural (HMF) and furfural (FF). Subsequently, FF and HMF were converted into other aromatic compounds, which then reacted with FF and HMF to form PL. Our study may pave the way for the efficient production of PL.

Amphiphilic hot-melt pressure sensitive adhesives for transdermal administration made from low melt-processing temperature OSISO copolymers

Herein, an anionic polymerization method was employed to synthesize a series of amphiphilic poly(ethylene oxide-b-styrene-b-isoprene-b-styrene-b-ethylene oxide) penta-block copolymers (OSISO). Their molecular structure and properties were comprehensively characterized using GPC,1H-NMR, thermodynamic rheological testing and water contact angle test. Notably, the hydrophilic characteristics exhibited a proportional increase with the rise in poly(ethylene oxide) (PEO) content, ranging from 1.3 to 12.6 wt%. The polystyrene blocks with low number-average molecular weight (2000–3500) reduced the copolymer melt viscosity, surpassing a tenfold decrease than the control sample within the temperature range of 50–150 °C. Resultantly, this series of OSISO copolymers could be used to develop amphiphilic hot-melt pressure-sensitive adhesives (HMPSAs) by low temperature hot-melt processing method (<120 °C). HMPSAs loaded with 2 wt% of geniposide, prepared by an optimized composition formula of OSISO copolymers, tackifiers, and plasticizers (in a ratio of 5:5:2), displayed excellent in vitro drug release performance. Additionally, these adhesives presented impressive 180° peeling strength (0.05–0.14 kN/m) without residues left on the substrate in the 180° peeling tests. The incorporation of PEO block significantly enhanced both the adhesive properties and accumulative drug release. Geniposide showed a burst release behavior with a moderate accumulative drug release (15–30 wt%), attributed to the PEO phase without crystallization behavior of long PEO chains.

Synthesis of shape memory bio-based crosslinked polymer: Poly(arbutin)-co-poly(tosyl arbutin)-co-poly(ethylene glycol)

Oxidative copolymerization of arbutin (Arb) with 6-O-tosyl-Arb (TArb) was performed in water media in the presence of a di-μ-hydroxo-bis[(N,N,N′,N′-tetramethylethylenediamine)copper(II)] chloride (Cu[tmeda]) catalyst under oxygen to produce the corresponding copolymer PArbxPTArby (where, x and y indicate the molar ratio) with a number-average molecular weight (Mn) ranging from 4.2 to 9.3 kDa depending on the polymerization temperature and the time. This copolymer was further reacted with poly(ethylene glycol) (PEG) with amino groups at the terminals (Mn = 8.0 kDa) (PEG8.0k2NH2) in a silicone mould at 100 °C for 24 h to give the bio-based PArbxPTArbyPEGz crosslinked copolymer (z indicates the molar equivalent of the NH2 functions in the PEG to TArb units). The results of differential scanning calorimetry, wide-angle X-ray analysis and polarizing optical microscope image measurements determined that the PEG domain was homogeneously dispersed within the film. The degree of crystallization of the PEG domain was calculated to be 59%–78% and the film swelled over 2100 vol% after immersion in water for 12 h. This bio-based film showed good shape memory after being moulded at 80 °C, maintaining its shape at 20 °C and quickly recovering its original shape upon reheating.

Non-isothermal kinetics of the organocatalytic ring-opening polymerization of ε-caprolactone with metal-free α‑hydroxy acids: Eco-friendly and facile synthesis process

Metal-free and green α‑hydroxy acids (AHA) such as l-malic (MA), DL-mandelic acid (MDL), and citric acid (CA) were successfully and effectively utilized as an effective initiator for the solvent-free ring-opening polymerization (ROP) of ε-caprolactone (ε-CL). The performance of AHAs in the polymerization of ε-CL was completely and powerfully investigated via the non-isothermal differential scanning calorimetry (DSC). The proceed of ROP of ε-CL with AHAs could be real-time monitored by the obtained polymerization exotherms at different heating rates. The polymerization exotherms obtained from the ROP of ε-CL with CA occurred at a lower temperature range than MA, and MDA, respectively. From the kinetics study, the average activation energy (Ea) values for the ROP of ε-CL with CA (38.0 ± 1.8 kJ mol−1) were lower than MA (45.2 ± 3.6 kJ mol−1) and MDA (48.8 ± 6.2 kJ mol−1). Using the first-order model fitting, the values of pre-exponential factor (lnA0) for the ROP of ε-CL with CA, MA, and MDA were 7.0 ± 0.3, 8.5 ± 0.2, and 8.9 ± 0.3, respectively. The effectiveness of AHAs in the synthesis of PCL was clarified by conducting a larger-scale (4.0000 g) polymerization using conventional heating and microwave (MW) irradiation methods. From conventional heating, the green AHAs produced PCL with the number average molecular weight (Mn) and dispersity (Đ) values in the range of 5.18 × 103 - 1.43 × 104 g mol−1 and 1.14–2.02, respectively. The irradiation by MW could enhance the synthesis of PCL by reducing the synthesis time. By using the MW power of 450 W and irradiation time of 30 min, the PLC was obtained from the ROP of ε-CL with MA and MDA initiators, and the Mn of the obtained PCL from MW heating was 4.28 × 103 - 8.45 × 103 g mol−1. The mechanism for the ROP of ε-CL with all AHAs was proposed through the activated monomer mechanism.

Increased reactive carboxyl and free alfa-amino groups from fish type I collagen peptides by Alcalase® hydrolysis exhibit higher antibacterial and antioxidant activities

Abstract This study aimed to generate low molecular weight peptides (LMWP) from fish collagen type I hydrolysed by increasing activity of Alcalase® from 0.0 to 12.0 (AU-A per 100 g) at 55 °C and 7.4 of pH for 3 h 40 min. The results showed that all enzyme activity levels caused 34–55 % reductions in protein recovery, 1.0–3.0 folds’ increase in free α-amino groups and 1.7–3.2 folds’ increase in carboxyl groups. Degree of hydrolysis ranged from 20 to 30 % with increasing enzyme activity. The number average molecular weight significantly reduced from 3200 g/mol in 0.0 AU-A per 100 g enzyme activity to 1151, 1398, 1175, 1040 and 1246 g/mol in 2.4, 4.8, 7.2, 9.6 and 12.0 AU-A per 100 g enzyme activities, respectively. Depending upon enzyme activity level, the produced LMWP with reactive carboxyl and amino end-groups exhibited 2.5- to 4.0-fold increases in antioxidant capacity and 1.0–3.5 log cfu/ml inhibition of four pathogen bacteria. Highest inhibition of 2.5 log cfu/ml in Escherichia coli was obtained from 2.4 AU-A per 100 g enzyme activity and 3.5 log cfu/ml in Listeria monocytogenes from 9.6 and 12.0 AU-A per 100 g enzyme activity levels. Infrared spectroscopy clearly identified reactive end-groups and showed remarkably differences in molar absorptivity of various molecular regions between non-enzyme and enzyme treated collagen type I molecule. A 9.6 and 12.0 AU-A per 100 g enzyme activity levels were found optimally effective to generate LMWP. In conclusion, LMWP exhibited high antioxidant and antibacterial activity due to increased functional reactive end-groups, and these bio-active peptides may have greater potentialities in various food and pharmaceutical applications.

Biomass-based renewable, eco-friendly nanofiber membrane: Large-scale fabrication and application in PM0.3 capture and oily wastewater purification

Biomass-based poly (trimethylene 2,5-furandicarboxylate) (PTF) was synthesized by the simple and low-cost direct esterification method. The high number-average molecular weight (Mn) of about 39.6 kDa was achieved for PTF with a polydispersity index (PDI) of 2.0, which was suitable for spinning. The electrospun PTF nanofiber membranes were fabricated firstly and displayed adjustable diameters, excellent mechanical properties (lifting 550 g weight, foldability) and large-scale preparation potential (area of 100 cm × 50 cm). More impressively, high initial surface potential (13.5 kV) was found for the electrospun in-suit electret membranes, which facilitated the capture of ultrafine PM particles. Subsequently, the PTF membrane showed exceptional particle capture capability with a filtration performance of 99.96 %, low pressure drops of 78 Pa, and a satisfactory quality factor of 0.1 Pa−1. PTF filters also demonstrated long-term service capability for purifying high PM2.5 concentration smoke (15 cycles, 55 min), and could be flexibly introduced into various practical scenarios. Additionally, based on the selective oil/water wettability of PTF membranes, which showed outstanding separation effects of oily wastewater(＞99.88 %, 15 cycles). Therefore, the development and application of the PTF nanofibers provided a sustainable alternative for separation/purification and various fields in the future.

Molecular-mass distribution of alkylphenolformaldehyde oligomers modified by imidazolines

The molecular weight distribution of monoalkyl(C8–C12)phenolformaldehyde oligomers modified with imidazolines based on sunfl ower or corn oil fatty acids and polyamines – diethylenetriamine, triethylenetetraamine, polyethylene polyamines was determined by gel-chromatography. The influence of the component and quantitative composition on the parameters of the number average and weight average molecular weights, as well as on the polydispersity of oligomers, was studied. Regularities have been revealed and assumptions have been made regarding repeating monoalkyl (C8-C12)phenol-formaldehyde fragments in the composition of oligomeric macromolecules.

High Molar Mass Polycarbonates as Closed-Loop Recyclable Thermoplastics.

Using carbon dioxide (CO2) to make recyclable thermoplastics could reduce greenhouse gas emissions associated with polymer manufacturing. CO2/cyclic epoxide ring-opening copolymerization (ROCOP) allows for >30 wt % of the polycarbonate to derive from CO2; so far, the field has largely focused on oligocarbonates. In contrast, efficient catalysts for high molar mass polycarbonates are underinvestigated, and the resulting thermoplastic structure-property relationships, processing, and recycling need to be elucidated. This work describes a new organometallic Mg(II)Co(II) catalyst that combines high productivity, low loading tolerance, and the highest polymerization control to yield polycarbonates with number average molecular weight (Mn) values from 4 to 130 kg mol-1, with narrow, monomodal distributions. It is used in the ROCOP of CO2 with bicyclic epoxides to produce a series of samples, each with Mn > 100 kg mol-1, of poly(cyclohexene carbonate) (PCHC), poly(vinyl-cyclohexene carbonate) (PvCHC), poly(ethyl-cyclohexene carbonate) (PeCHC, by hydrogenation of PvCHC), and poly(cyclopentene carbonate) (PCPC). All these materials are amorphous thermoplastics, with high glass transition temperatures (85 < Tg < 126 °C, by differential scanning calorimetry) and high thermal stability (Td > 260 °C). The cyclic ring substituents mediate the materials' chain entanglements, viscosity, and glass transition temperatures. Specifically, PCPC was found to have 10× lower entanglement molecular weight (Me)n and 100× lower zero-shear viscosity compared to those of PCHC, showing potential as a future thermoplastic. All these high molecular weight polymers are fully recyclable, either by reprocessing or by using the Mg(II)Co(II) catalyst for highly selective depolymerizations to epoxides and CO2. PCPC shows the fastest depolymerization rates, achieving an activity of 2500 h-1 and >99% selectivity for cyclopentene oxide and CO2.

Designing hydrolysis-resistant Ti/Zn bimetallic catalyst based on the coordination activation mechanism to synthesize high molecular weight poly (1,5-pentene terephthalate) (PPeT)

The high molecular weight poly (1,5-pentene terephthalate) synthesis and its molecular weight distribution control are still challenging, and one of the critical problems is the lack of efficient catalysts. Based on the coordination activation mechanism, a heavy metal free, hydrolysis-resistant and 1,5-Pentanediol soluble Ti/Zn bimetallic catalyst has been synthesized and characterized. The Ti/Zn bimetallic active center increases electron-absorption effect in catalyst to promote the esterification process, and the diol-metal alkoxide structure increases the production of oligomer ligands, which can effectively improve transesterification efficiency. The optimal polycondensation reaction temperature for PPeT synthesized with Ti/Zn bimetallic catalyst can be reduced to 230 °C, with an average reaction rate of 90.33 g mol−1·min−1. The number average molecular weight of PPeT can be increased to 3.02 × 104 g mol−1, and the polymer dispersive index can be as low as 1.90. As the number average molecular weight increases, poly (1,5-pentene terephthalate) has a tensile strength of 29.80 MPa and an elongation at break of 16.39%. More importantly, Ti/Zn bimetallic catalyst retains excellent catalytic activity after treatment with boiling water and has significantly improved hydrolysis resistance and storage stability. Ti/Zn bimetallic catalyst can significantly increase the molecular weight and melt viscosity of poly (1,5-pentene terephthalate), giving it the potential for a wider range of applications in plastics and fiber fields.

Collagen peptides from sturgeon swim bladder prolong the lifespan and healthspan in Caenorhabditis elegans.

Sturgeon is a popular aquaculture species in many countries. Its swim bladder is rich in collagen but has not yet been exploited scientifically. Collagen peptides (CPs) prepared from sturgeon swim bladder by trypsinolysis had an average molecular weight of 528.5 Da and consisted of 407 peptides, 16.1% of the content of which was GFPGADGSAGPK. The CPs at 25 mg mL-1 extended the lifespan of Caenorhabditis elegans by 22.6%, which was significantly higher than the extension achieved by other hydrolysis methods and source materials. They also improved fitness-related traits (body size, motor capacity, oxidative stress, cell apoptosis, and epidermal barrier function), indicating prolonged healthspan. Transcriptome analysis showed that the effect was mediated by the mitogen-activated protein kinase pathway, which enhanced stress resistance, the insulin/IGF-1 pathway, which inhibited protein aggregation, and the NHR-80/FAT-6 pathway, which regulated lipid metabolism. Collagen peptides from sturgeon swim bladder by trypsinolysis prolonged the lifespan and healthspan in C. elegans, and might be promising anti-aging agents. © 2024 Society of Chemical Industry.

Effects of Auricularia auricula-judae (Bull.) Quél. polysaccharide acid hydrolysate on glucose metabolism in diabetic mice under oxidative stress

BackgroundOxidative stress can lead to uncontrolled glucose metabolism and, thus, diabetes. Auricularia auricula-judae (Bull.) Quél. polysaccharides possess biological activities, such as antioxidant and hypoglycemic effects, but their mechanism of their acid hydrolysates on oxidative stress-injured glucose metabolism disorders is unclear. PurposeUsing diabetic mice, we investigated the effect of the acid hydrolysate of polysaccharides from Auricularia auricula-judae (Bull.) Quél. on improving diabetes. Study design and MethodsThe structural information of sample polysaccharides was measured by high performance gel permeation chromatography, nuclear magnetic resolution, and high performance liquid chromatography. The diabetic model was established by intraperitoneal injection of streptozotocin. For eight consecutive weeks, the mice were orally administered sample polysaccharides (100, 200, and 300 mg/kg b.w. per day) for intervention. The improvement effect of the samples on diabetes was explored by detecting the changes in biochemical indicators in mice, and the underlying mechanism was studied by transcriptomic and metabolomic analysis. ResultsThe results showed that acid hydrolysate of Auricularia auricula-judae (Bull.) Quél. polysaccharides consisted mainly of mannose, xylose, glucuronic acid, and glucose; its weight-averaged molecular weight was 6.3842 × 104 Dalton, its number average molecular weight was 2.9594 × 104 Dalton; and the molecule contained α-Glc(1→4)-, β-Glc(1→3)-, and β-Man(1→4)-linked glycosidic bonds. A total of 100 mg/kg b.w. per day sample was the best intervention concentration. After eight weeks of intervention, the sample polysaccharides significantly reduced dynamic blood glucose and serum lipids, enhanced antioxidant enzyme activities, promoted glucagon like peptide-1 and insulin secretion, improved insulin sensitivity and alleviated insulin resistance in diabetic mice. Transcriptomic and metabolomic analyses showed that sample polysaccharides was able to ameliorate disorders of glucose metabolism by modulating gene expression such as glucokinase; and modulate the state of oxidative stress in mice in vivo by regulating the glutathione metabolism pathway. ConclusionAcid hydrolysate of Auricularia auricula-judae (Bull.) Quél. polysaccharides improved glucose metabolism disorders by slowing down the oxidative stress injury in mice, thereby alleviating diabetes. This study provided a basis for determining the underlying mechanism of the antidiabetic effect of Auricularia auricula-judae (Bull.) Quél. polysaccharides, which would significantly improve the deep development and application of these materials in diabetes control.

High Polymer Molecular Weight Yields Solar Cells with Simultaneously Improved Performance and Thermal Stability.

Simple synthetic routes, high active layer thickness tolerance as well as stable organic solar cells are relentlessly pursued as key enabling traits for the upscaling of organic photovoltaics. Here, the potential to address these issues by tuning donor polymer molecular weight is investigated. Specifically, the focus is on PTQ10, a polymer with low synthetic complexity, with number average molecular weights of 2.4, 6.2, 16.8, 52.9, and 54.4kDa, in combination with three different non-fullerene acceptors, namely Y6, Y12, and IDIC. Molecular weight, indeed, unlocks a threefold increase in power conversion efficiency for these blends. Importantly, efficiencies above 10% for blade coated devices with thicknesses between 200 and 350nm for blends incorporating high molecular weight donor are shown. Spectroscopic, GIWAXS and charge carrier mobility data suggest that the strong photocurrent improvement with molecular weight is related to both, improved electronic transport and polymer contribution to exciton generation. Moreover, it is demonstrated that solar cells based on high molecular weight PTQ10 are more thermally stable due to a higher glass transition temperature, thus also improving device stability.

Accelerating Biodegradation: Enhancing Poly(lactic acid) Breakdown at Mesophilic Environmental Conditions with Biostimulants.

Poly(lactic acid) (PLA) has garnered interest due to its low environmental footprint and ability to replace conventional polymers and be disposed of in industrial composting environments. Although PLA is compostable when subjected to a suitable set of conditions, its broader acceptance in industrial composting facilities has been affected adversely due to longer degradation timeframes than the readily biodegradable organic waste fraction. PLA must be fully exposed to thermophilic conditions for prolonged periods to biodegrade, which has restricted its adoption and hindered its acceptance in industrial composting facilities, negating its home composting potential. Thus, enhancing PLA biodegradation is crucial to expand its acceptance. PLA's biodegradability is investigated in a compost matrix under mesophilic conditions at 37 °C for 180 days by biostimulating the compost environment with skim milk, gelatin, and ethyl lactate to enhance the different stages of PLA biodegradation. The evolved CO2, number average molecular weight (Mn), and crystallinity evolution are tracked. To achieve a Mn ≲ 10kDa for PLA, the biodegradation rate is accelerated by 15% by adding skim milk, 25% by adding gelatin, and 22% by adding ethyl lactate. This work shows potential techniques to help biodegrade PLA in home composting setting by adding biostimulants.

Immunoregulatory activity of an alkaline-precipitated polysaccharide CGP-AP produced by Chaetomium globosum CGMCC 6882

This work characterized the structural features and investigated the immunomodulatory activity of an alkaline-precipitated polysaccharide fraction produced by Chaetomium globosum CGMCC 6882 (CGP-AP) in RAW 264.7 macrophages. The CGP-AP yield was 0.93 ± 0.08 g/L, which contained 98.33% ± 2.04% (w/w) carbohydrate and 1.52% ± 0.26% (w/w) protein. Structural analysis showed that CGP-AP comprised glucose (99.51%) and arabinose (0.49%), its weight (Mw) and number (Mn) average molecular weights were 0.948 and 0.55 kDa, and its polydispersity (Mw/Mn) was 1.724. In vitro immunomodulatory results show that CGP-AP stimulated nitric oxide production and tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and IL-8 secretion via upregulation of the expression levels of related genes in RAW 264.7 macrophages. Meanwhile, CGP-AP upregulated the expression levels of proinflammatory genes (inducible nitric oxide synthase and cyclooxygenase-2 COX-2). Furthermore, CGP-AP improved the antioxidant status of RAW 264.7 cells by increasing antioxidase (superoxide dismutase, catalase, and glutathione peroxidase) levels and enhancing the mRNA expression of nuclear factor erythroid-2 related factor 2. The above results indicate that CGP-AP may be used as a potential immunomodulator in the pharmaceutical industry.

Prevention of surface defects in calendered poly(vinyl chloride) sheets using a succinate‐capped poly(caprolactone) additive

AbstractSurface defects known as “gas checks” often mar the surfaces of poly(vinyl chloride) (PVC) calendered films. These defects are typically prevented through changes in the calender operating parameters, a costly exercise which also limits the sheet thickness and the production rate. Adding a low concentration of poly(caprolactone) (PCL)‐based star‐shaped compound can eliminate gas check defects in PVC calendering. The effects of a triheptylsuccinate‐terminated PCL with a PCL triol core and number average molecular weight of 540 g/mol (i.e., PCL540‐[(succ)‐C7]3) has been investigated on the material, thermal, and processing properties of PVC blends containing diisononyl phthalate (DINP) as a primary plasticizer and PCL540‐[(succ)‐C7]3 in low quantities (i.e., 0, 5, or 10 parts per hundred rubber (phr)) as a secondary plasticizer and processing aid. The most significant differences between PVC blends containing PCL540‐[(succ)‐C7]3 and those without are in the rheological properties of the PVC blends at higher temperatures and lower angular frequencies. Under these conditions, PVC blends containing 10 phr of PCL540‐[(succ)‐C7]3 have a complex viscosity nearly three times higher than those containing only DINP. PVC/PCL540‐[(succ)‐C7]3 blends had comparable tensile properties to those containing only DINP, with no significant change in maximum elongation and a small but significant increase of 28% in maximum stress. The addition of PCL540‐[(succ)‐C7]3 made it possible to produce calendered films without gas checks that were twice as thick as those produced in its absence. In addition to reduced wastage of marred films, the increased calender operating range for PVC films containing PCL540‐[(succ)‐C7]3 has the potential to significantly reduce energy costs for the calendering of thick PVC films.