Average Molecular Weight Research Articles

Development and mechanism research of hydrophobic associative polymer drag reducing agents

ABSTRACT The challenge of insufficient proppant transportation capacity in slick water remains unresolved. To tackle this concern, a hydrophobically associating water-soluble polymer (HAWP), characterized by a low molecular weight (MW) of 8.11 × 105 g/mol, was successfully synthesized via a photo-initiation method. The drag reduction mechanism of the material was characterized through nuclear magnetic resonance and rheological performance testing. The drag reduction mechanism of the material was characterized through nuclear magnetic resonance and rheological performance testing. The results show that in comparison to conventional drag reducers in slick water with an average MW of approximately 1 × 107 g/mol, HAWP demonstrates significantly reduced MW. The rheological test results indicate that upon addition of sodium dodecyl benzene sulfonate (SDS, 200 mg/L) to the HAWP solution (0.3 wt%), the storage modulus experienced a substantial increase from 0.14 Pa to 7.42 Pa, demonstrating enhanced mechanical properties. Meanwhile, drag reduction (DR) tests showed that the efficiency of drag reduction achieved by the polymer system (PS) drag reducer was comparable to that of conventional linear polymers. This research achievement effectively addresses the challenges of low molecular weight and resistance reduction encountered in previous endeavors.

Bitumen-Biopolymer Materials Modified with Polylactic Acid with Improved Physical and Chemical Properties

With the continuous expansion of the global automobile fleet, there is an escalating demand to enhance and maintain current road infrastructure. Given the information provided, there will be a growing demand for bitumen, a key raw material used in the manufacturing of asphalt. Bitumen may account for up to 60% of the total usage in asphalt production. This study aims to determine the effect of different content of polylactic acid (PLA) on the change in the chemical and physical properties of biopolymer bitumen during its modification. This study was carried out by using a sample of petroleum road bitumen from CASPI BITUM (Kazakhstan) and a sample of PLA from Zhejiang Hisun (China). As a part of the research, the change of quality indicators of biopolymer bitumen when adding 4%–10% of PLA to it has been established. The results showed that the values of the average molecular weight and average molar mass increased with increasing the content of PLA in biopolymer bitumen. In particular, when the PLA content in biopolymer bitumen increased up to 10%, the average molecular weight of the biopolymer bitumen increased from 1,263 to 2,759 Mw and the average molar mass increased from 1,215 to 1,395 Mn. It was shown that increasing the PLA content in biopolymer bitumen from 0% to 10% leads to an increase in the softening temperature from 47 to 70°C or ∼ 49%. It was found that all examined samples of biopolymer bitumen are characterized by increased plasticity at 25°C (>100 cm). It has been established that the addition of 8% PLA to bitumen allows one to obtain a biopolymer bitumen of optimal quality. The results obtained can be used to produce road biopolymer bitumen.

Hydrogels with Ultrasound-Treated Hyaluronic Acid Regulate CD44-Mediated Angiogenic Potential of Human Vascular Endothelial Cells In Vitro

The development of hydrogels that allow vascular endothelial cells to form capillary-like networks is critical for advancing tissue engineering and drug discovery. In this study, we developed hydrogels composed of phenolated hyaluronic acid (HA-Ph) with an average molecular weight of 490–159 kDa via sonication in an aqueous solution. These hydrogels were synthesized by the horseradish peroxidase-catalyzed crosslinking of phenol moieties in the presence of hydrogen peroxide and phenolated gelatin. The sonication-degraded HA-Ph (198 kDa) significantly enhanced the migration ability of human umbilical vein endothelial cells (HUVECs) on cell culture plates when added to the medium compared to the original HA-Ph (490 kDa) and less-degraded HA-Ph (312–399 kDa). In addition, HUVECs cultured on these hydrogels formed networks that did not occur on hydrogels made from the original HA-Ph. CD44 expression and PI3K gene expression, both markers related to angiogenesis, were 3.5- and 1.8-fold higher, respectively, in cells cultured on sonication-degraded HA-Ph hydrogels than in those cultured on hydrogels comprising the original HA-Ph. These results highlight the potential of hydrogels containing sonication-degraded HA-Ph for tissue engineering and drug-screening applications involving human vascular endothelial cells.

Non‐isocyanate polyurethane‐acrylate as UV‐ and thermo‐responsive plasticizer for thermoplastic elastomer

AbstractA UV‐ and thermo‐responsive polyurethane‐acrylate prepolymer was synthesized from palm olein (POo) via a non‐isocyanate route. The process included epoxidation of POo, carbonation of epoxidized palm olein (EPOo) into polycyclic carbonate in a solvent‐free and mild condition (100°C, 1 atm), followed by reacting with ethylene diamine and acrylic acid. The chemical structure of the non‐isocyanate polyurethane‐acrylate (NIPUA) prepolymer was elucidated by 1H and 13C nuclear magnetic resonance (NMR) and Fourier transform‐infrared spectroscopy (FTIR), while weight average molecular weight of NIPUA was determined by gel permeation chromatography (GPC). The NIPUA (0–20 wt%) was incorporated with thermoplastic elastomer (TPE) as a plasticizer and cured under UV light and thermal stimulations. The cured NIPUA/TPE films were characterized by FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile strength test. Under UV and thermal stimulations, the NIPUA/TPE demonstrated enhanced tensile properties (elongation at break >1280%, Young's modulus ~25 MPa), thermal properties (lower Tg), lower water contact angle, and shortened curing time as compared with the blank TPE. The 20 wt% NIPUA/TPE films exhibited susceptibility to enzymatic biodegradation and noncytotoxic to HEK 293 cells in vitro, demonstrated it's potential as a UV‐ and thermo‐responsive plasticizer for TPE in manufacturing of medical devices.

Extraction of Pithecellobium clypearia Benth polysaccharides by dual-frequency ultrasound-assisted extraction: Structural characterization, antioxidant, hypoglycemic and anti-hyperlipidemic activities

In this research, the extraction process of polysaccharides from Pithecellobium clypearia Benth (PCBPs) was optimized using dual-frequency ultrasound-assisted extraction (DUAE). The biological activities of PCBPs were investigated by in vitro antioxidant, hypoglycemic, and anti-hyperlipidemic assay. High-performance anion-exchange chromatography, high-performance gel permeation chromatography, SEM, UV–Vis spectroscopy, and FT-IR spectra were used to analyze the monosaccharide composition, molecular weight, microscopic morphology, and characteristic structure of PCBPs. The results showed that the maximum extraction rate of PCBPs was 9.90 ± 0.16% when the ultrasonic time was 8 min, the liquid-to-material ratio was 32 mL/g, and the ultrasonic power was 510 W. The PCBPs also possessed excellent in vitro antioxidant, hypoglycemic, and anti-hyperlipidemic activities. In addition, the average molecular weight of PCBPs was 15.07 kDa. PCBPs consisted of rhamnose, arabinose, galactose, glucose, xylose, mannose, and glucuronic acid, with the molar ratios of 11.07%, 18.54%, 48.17%, 10.44%, 4.62%, 4.96%, and 2.20%, respectively. Moreover, the results of SEM showed that PCBPs mainly showed a fine spherical mesh structure. The above studies provided a valuable theoretical basis for the subsequent in-depth study of PCBPs.

Crystallographic Texture Evolution in 3D Printed Polyethylene Reactor Blends.

In this work, crystallographic texture evolution in 3D printed trimodal polyethylene (PE) blends and high-density PE (HDPE) benchmark material were investigated to quantify the resulting material anisotropy, and the results were compared to materials made from conventional injection molded (IM) samples. Trimodal PE reactor blends consisting of HDPE, ultrahigh molecular weight PE (UHMWPE), and HDPE_wax have been used for 3D printing and injection molding. Changes in the preferred orientation and distribution of crystallites, i.e., texture evolution, were quantified utilizing the wide angle X-ray diffraction through pole figures and orientation distribution functions (ODFs) for 3D printed and IM samples. Since the change in weight-average molecular weight (Mw) of the blend was expected to significantly affect the resulting crystallinity and orientation, the overall Mw of the trimodal PE blend was varied while keeping the UHMWPE component weight fraction to 10% in the blend. The resulting texture was analyzed by varying the overall Mw of the trimodal blend and the process parameters in 3D printing and compared to the texture of conventional IM samples. The printing speed and orientation (defined with respect to the axis along the length of the samples) were used as the variable process parameters for 3D printing. The degree of anisotropy increases with an increase in the nonuniform distribution of intensities in pole figures and ODFs. All the highest intensity major texture components in IM and 3D printed samples (0° printing orientation) of reactor blends are observed to have crystals oriented in [001] or [001̅]. Overall, for the same throughput, 3D printed samples in the 0° orientation showed greater texture evolution and higher anisotropy compared to IM samples. Most notably, an increase in 3D printing speed increased the crystalline distribution closer to the 0° direction, increasing the anisotropy, while deviation from this printing orientation reduced crystalline distribution closer to the 0° direction, thus increasing isotropy. This demonstrates that tailoring material properties in specific directions can be achieved more effectively with 3D printing than with the injection molding process. Change in the overall Mw of the trimodal PE blend changed the preferential orientation distribution of the crystal planes to some degree. However, the degree of anisotropy remained the same in almost all cases, indicating that the effect of molecular weight distribution is not as significant as the printing speed and printing orientation in tailoring the resulting properties. The 3D printing process parameters (speed and orientation) were shown to have more influence on the texture than the material parameters associated with the blend.

Preparation of Rehmanniae Radix Praeparata polysaccharide iron(III) complex and evaluation of its biological activity.

This study extracted and purified a polysaccharide from Rehmanniae radix praeparata (RGP) with an average molecular weight. The structural characteristicsof RGP and its iron(III) complex, RGP-Fe(III),were examinedfor their antioxidant properties and potential in treating iron deficiency anemia (IDA). Analysis revealedthatRGP comprised Man, Rha, Gal,and Xyl, with a sugar residue skeleton featuring1→3; 1→2, 3; and 1→2,3, 4 linkages, among others. RGP-Fe(III) had amolecular weight of 4.39×104 Da.Notably, RGP-Fe(III) exhibited superiorantioxidant activity compared toRGPalone. InIDA rat models,treatmentwithRGP-Fe(III)led to increasedweight gain, restorationof keyblood parameters including hemoglobin, red blood cells,and mean hemoglobin content, elevatedserum ironlevels,and decreasedtotal iron-binding capacity.Histologicalexamination revealedno observabletoxic effects of RGP-Fe(III) on the liver and spleen.These findings suggest the potential of RGP-Fe(III) as a therapeutic agent for managing IDA and highlight its promising antioxidant properties.

From laboratory to industrial use: Understanding process variation during enzymatic protein hydrolysis with dry film fourier-transform infrared spectroscopy

Industries are continuously looking for dedicated sensor solutions for evaluating the chemical composition of products that can provide valuable insights into process control, process optimization, and product quality. A rapid and robust analytical method, Fourier-Transform Infrared (FTIR) spectroscopy, holds significant potential in this regard as it provides detailed compositional values of food nutrients. The main aim of the present study was to use dry film FTIR spectroscopy as an analytical tool to characterize products from an industrial enzymatic protein hydrolysis process and link this to understand industrial process variations. For this purpose, 463 protein hydrolysate samples were obtained from an industrial enzymatic protein hydrolysis plant. In the same period, systematic variations in process parameters such as raw material composition, enzyme type, and water addition, were performed. All samples were analyzed using dry film FTIR spectroscopy. Two subsets containing 200 and 68 hydrolysate samples were chosen for measuring average molecular weight (AMW) and collagen content respectively, providing reference data for constructing calibration models based on partial least squares regression (PLSR). The percentage of low molecular weight constituents was derived from the molecular weight distribution of size exclusion chromatograms of protein hydrolysates and also used in the modeling. Calibration models for the prediction of AMW, low molecular weight constituents, and collagen content were obtained with a good fit and lower estimation errors. Principal component analysis (PCA) of protein hydrolysates' FTIR spectra effectively differentiated process variations (enzyme types and raw materials) without extensive reference analysis. One-factor analysis of variance (ANOVA) tests was used to observe the impact of process variation on product quality. FTIR proved to be a sensitive method for liquid protein analysis and process control with a significant potential in process optimization approaches. To the authors’ knowledge, this is the first time dry film FTIR spectroscopy has been used to evaluate an industrial bioprocess with designed process variations.

Dissolved organic matter quality in thermokarst lake water and sediments across a permafrost gradient, Western Siberia

Thermokarst (thaw) lakes of permafrost peatlands are among the most important sentinels of climate change and sizable contributors of greenhouse gas emissions (GHG) in high latitudes. These lakes are humic, often acidic and exhibit fast growing/drainage depending on the local environmental and permafrost thaw. In contrast to good knowledge of the thermokarst lake water hydrochemistry and GHG fluxes, the sediments pore waters remain virtually unknown, despite the fact that these are hot spots of biogeochemical processes including GHG generation. Towards better understating of dissolved organic matter (DOM) quality at the lake water – sediment interface and in the sediments pore waters, here we studied concentration and optical (UV, visual) properties of DOM of 11 thermokarst lakes located in four permafrost zones of Western Siberia Lowland. We found systematic evaluation of DOM concentration, SUVA and various optical parameters along the vertical profile of lake sediments. The lake size and hence, the stage of lake development, had generally weak control on DOM quality.The permafrost zone exhibited clear impact on DOM porewater concentration, optical characteristics, aromaticity and weight average molecular weight (WAMW). The lowest quality of DOM, reflected in highest SUVA and WAMW, corresponding to the dominance of terrestrial sources, was observed at the southern boundary of the permafrost, in the sporadic/discontinuous zone. This suggests active mobilization of organic matter leachates from the interstitial peat and soil porewaters to the lake, presumably via subsurface or suprapermafrost influx. Applying a substitute space for time scenario for future evolution of OM characteristics in thermokarst lake sediments of Western Siberia, we foresee a decrease of DOM quality, molecular weight and potential bioavailability in lakes of continuous permafrost zone, and an increase in these parameters in the sporadic/discontinuous permafrost zone.

Characterization of Fish Skin Hydrolysates Exhibiting Dipeptidyl Peptidase IV Inhibitory Activity

Dipeptidyl peptidase IV (DPP-IV) inhibitors are antidiabetic drugs that can lower blood sugar levels. There are still few reports on the DPP-IV inhibitory activity of peptides obtained from discarded fish skin. Therefore, we prepared various enzymatic hydrolysates using the skins of six fish species and investigated their DPP-IV inhibitory effects. As a result, it was found that the DPP-IV inhibitory activity of yellowtail hydrolysate by Alcalase was higher than that of other enzymes. In addition, the IC50 after ethanol fractionation was found to be lower in yellowtail and eel skin hydrolysate. Amino acid composition analysis showed that the hydrolysate obtained from the skin of the yellowtail contained the highest amount of Gly, followed by Pro, Hyp, and Ala, indicating that it was a peptide derived from type I collagen. Fractionation with ethanol showed that the DPP-IV inhibitory components were contained in the low molecular weight fraction. The artificial digestion test observed no DPP-IV inhibitory activity or average molecular weight change. The DPP-IV inhibitory peptide obtained from fish skin has the potential to be applied as a food material to various food products.

Characterization Electrospun Nanofibers Based on Cellulose Triacetate Synthesized from Licorice Root Cellulose

Cellulose triacetate (CTA) nanofibers were formed by electrospinning using two binary solvent systems: methylene chloride/ethanol and chloroform/acetone. Previously, licorice root cellulose (LRC) with a degree of polymerization (DP) of 710 was extracted from licorice root waste by alkaline treatment and hydrogen peroxide bleaching at high temperatures. Then CTA with a degree of substitution (DS) of 2.9 and an average molecular weight of 175 kDa was synthesized from LRC using acetic acid and acetic anhydride, sulfuric acid was as a catalyst. The influence of the electrospinning process and various solvent systems on the morphology and structure of nanofibers is studied. The structure and morphology of the nanofibers were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and the sorption characteristics were also investigated. The results showed that the morphology and structure of nanofibers depended on the solvent mixture used. The average diameters of the CTA nanofibers with grooved morphology varied 200-700 nm (solvent methylene chloride/ethanol) and the dumbbell-shaped (flat ribbon) CTA nanofibers in a wide range from 200 nm to 4 mkm (solvent chloroform/acetone).

The isolation, structure characterizations and anti-photoaging activities of sulfated polysaccharides isolated from Sargassum fusiforme

BackgroundOur previous study found that crude polysaccharide extracted from Sargassum fusiforme (PSF) exhibited excellent anti-photoaging activity, but the composition responsible for this activity remained unknown.ResultsIn this study, three fractions (P1, P2 and P3) obtained by hot water extraction and column chromatographic separation from PSF were structurally characterized. The anti-photoaging activities of these isolated polysaccharides were evaluated using HaCaT cells. The results showed that P1, P2 and P3 were acidic polysaccharides with 42.94%, 40.75% and 2.21% uronic acid. In addition, the contents of sulfate groups were 3.01%, 10.05% and 7.44%, respectively. Moreover, their content of reducing sugar was low, and none of the fractions had a triple-stranded helical structure. P1 had the largest average molecular weight of 208.89 kDa, while P2 and P3 had a relatively lower molecular weight of 154.09 and 151.71 kDa, respectively. Treatment with P2 effectively safeguarded the viability of HaCaT cells exposed to UVB irradiation. Additionally, it inhibited the secretion of MMP-1 and MMP-3 while elevating the content of hydroxyproline (HYP) in the cell supernatant. Methylation and NMR analysis suggested the main structure of P2 might be → [4)-β-ManA-(1]23 → 4)-β-ManA-(1 → 3)-β-d-Glcp-(1 → 4)-β-d-Glcp-(1 → 4)-β-d-Glcp-(1 → . The two terminal groups of β-ManA-(1 → and β-d-Glcp-(1 → were connected via the glycosidic bonds of → 3, 4)-O-3 in β-ManA-(1 → and O-6 in → 4, 6)-β-d-Glcp-(1 → , respectively.ConclusionsThese findings will open new avenues for exploring the potential use of Sargassum fusiforme polysaccharide, particularly P2, as a functional ingredient with anti-photoaging activity.Graphical

Effects of UV/H2O2 Degradation on the Physicochemical and Antibacterial Properties of Fucoidan.

The applications of fucoidan in the food industry were limited due to its high molecular weight and low solubility. Moderate degradation was required to depolymerize fucoidan. A few studies have reported that fucoidan has potential antibacterial activity, but its antibacterial mechanism needs further investigation. In this study, the degraded fucoidans were obtained after ultraviolet/hydrogen peroxide treatment (UV/H2O2) at different times. Their physicochemical properties and antibacterial activities against Staphylococcus aureus and Escherichia coli were investigated. The results showed that the average molecular weights of degraded fucoidans were significantly decreased (up to 22.04 times). They were mainly composed of fucose, galactose, and some glucuronic acid. Fucoidan degraded for 90 min (DFuc-90) showed the strongest antibacterial activities against Staphylococcus aureus and Escherichia coli, with inhibition zones of 27.70 + 0.84 mm and 9.25 + 0.61 mm, respectively. The minimum inhibitory concentrations (MIC) were 8 mg/mL and 4 mg/mL, respectively. DFuc-90 could inhibit the bacteria by damaging the cell wall, accumulating intracellular reactive oxygen species, reducing adenosine triphosphate synthesis, and inhibiting bacterial metabolic activity. Therefore, UV/H2O2 treatment could effectively degrade fucoidan and enhance its antibacterial activity.

Polyhydroxyalkanoate Copolymer Production by Recombinant Ralstonia eutropha Strain 1F2 from Fructose or Carbon Dioxide as Sole Carbon Source.

Ralstonia eutropha strain H16 is a chemoautotrophic bacterium that oxidizes hydrogen and accumulates poly[(R)-3-hydroxybutyrate] [P(3HB)], a prominent polyhydroxyalkanoate (PHA), within its cell. R. eutropha utilizes fructose or CO2 as its sole carbon source for this process. A PHA-negative mutant of strain H16, known as R. eutropha strain PHB-4, cannot produce PHA. Strain 1F2, derived from strain PHB-4, is a leucine analog-resistant mutant. Remarkably, the recombinant 1F2 strain exhibits the capacity to synthesize 3HB-based PHA copolymers containing 3-hydroxyvalerate (3HV) and 3-hydroxy-4-methyvalerate (3H4MV) comonomer units from fructose or CO2. This ability is conferred by the expression of a broad substrate-specific PHA synthase and tolerance to feedback inhibition of branched amino acids. However, the total amount of comonomer units incorporated into PHA was up to around 5 mol%. In this study, strain 1F2 underwent genetic engineering to augment the comonomer supply incorporated into PHA. This enhancement involved several modifications, including the additional expression of the broad substrate-specific 3-ketothiolase gene (bktB), the heterologous expression of the 2-ketoacid decarboxylase gene (kivd), and the phenylacetaldehyde dehydrogenase gene (padA). Furthermore, the genome of strain 1F2 was altered through the deletion of the 3-hydroxyacyl-CoA dehydrogenase gene (hbdH). The introduction of bktB-kivd-padA resulted in increased 3HV incorporation, reaching 13.9 mol% from fructose and 6.4 mol% from CO2. Additionally, the hbdH deletion resulted in the production of PHA copolymers containing (S)-3-hydroxy-2-methylpropionate (3H2MP). Interestingly, hbdH deletion increased the weight-average molecular weight of the PHA to over 3.0 × 106 on fructose. Thus, it demonstrates the positive effects of hbdH deletion on the copolymer composition and molecular weight of PHA.

Optimization of Composite Enzymatic Extraction, Structural Characterization and Biological Activity of Soluble Dietary Fiber from Akebia trifoliata Peel.

In order to reduce the waste of Akebia trifoliata peel and maximize its utilization, in this study, on the basis of a single-factor experiment and the response surface method, the optimum technological conditions for the extraction of soluble dietary fiber from Akebia trifoliata peel with the compound enzyme method were obtained. The chemical composition, physical and chemical properties, structural characterization and biological activity of the purified soluble dietary fiber (AP-SDF) from the Akebia trifoliata peel were analyzed. We discovered that that the optimum yield was 20.87% under the conditions of cellulase addition 600 U/g, enzymolysis time 100 min, solid-liquid ratio 1:24 g/mL and enzymolysis temperature 51 °C. At the same time, AP-SDF was a porous network structure cellulose type I acidic polysaccharose mainly composed of arabinoxylan (36.03%), galacturonic acid (27.40%) and glucose (19.00%), which possessed the structural characteristic peaks of the infrared spectra of polysaccharides and the average molecular weight (Mw) was 95.52 kDa with good uniformity. In addition, the AP-SDF exhibited high oil-holding capacity (15.11 g/g), good water-holding capacity and swelling capacity, a certain antioxidant capacity in vitro, hypoglycemic activity in vitro for α-glucosidase inhibition and hypolipidemic activity in vitro for the binding ability of bile acids and cholesterol. These results will provide a theoretical basis for the development of functional products with antioxidant, hypoglycemic and hypolipidemic effects, which have certain application value in related industries.

The effect of molecular weight of chitosan on the size of chitosan-Cu2+ complex-stabilized sulfur nanoparticles

Chitosan (CS) samples with average molecular weight (Mw) of 80.4, 61.8, and 45.2 kDa were prepared by the heterogeneous degradation of CS using 1% H2O2 solution under ambient conditions. The degree of deacetylation (DD) of the resultant CS was almost unchanged compared with that of the original CS. The sulfur nanoparticles (SNPs) were prepared by acidification of sodium thiosulfate (Na2S2O3) in a CS-Cu2+ complex solution. The influence of Mw CS on the size of SNPs was investigated. The average size of the SNPs/CS-Cu2+ complexes measured through Transmission electron microscopy (TEM) images was 25.1, 32.3, and 48.3 nm for using CS with Mw of 80.4, 61.8, and 45.2 kDa, respectively. The obtained SNPs/CS-Cu2+ complexes were also characterized by Ultraviolet-visible (UV-Vis), Fourier-transform infrared (FTIR), and x-ray diffraction (XRD) measurements. The synthetic method is favorable for large-scale production. Furthermore, the SNPs/CS-Cu2+ complex can be used as an agent for controlling plant disease in agriculture.

Photochemistry of plateau lake-derived dissolved organic matter: Reactive species generation and effects on 17β-estradiol photodegradation

Naturally strong ultraviolet irradiation at high altitudes causes photobleaching of plateau lake DOM (P-DOM) and affects its photochemical activity. However, the photoreactivity of P-DOM has remained unclear under natural photobleaching condition. Here, six P-DOM samples isolated from plateau lakes in Yunnan Province, China as well as two reference DOM as comparisons were used to explore the photogeneration of reactive species (RS) and their effects on 17β-estradiol photodegradation. Compared with SRHA/SRFA, P-DOM has lower aromaticity, average molecular weight, and electron-donating capacity. The quantum yields of triplet state P-DOM (3P-DOM⁎), 1O2, and ∙OH produced in P-DOM solutions were greatly higher than those of reference DOM. The RS quantum yields had positive linear correlations with E2/E3 and SR, whereas were negatively linear correlated with SUVA25. Radical quenching experiments showed that 3P-DOM⁎ was the prominent RS for 17β-estradiol photodegradation, and its contribution exceeded 70% for each of P-DOM. 3P-DOM⁎-mediated photodegradation was mainly attributed to the electron-transfer reactions with an average second-order rate constant of 4.62×109M-1s-1, indicating the strong photoreactivity towards 17β-estradiol. These findings demonstrate that P-DOM is an efficient photosensitizer for RS production, among which 3P-DOM⁎ may play an important role in enhanced photodegradation for organic micropollutants in plateau lake enriched with DOM. Environmental ImplicationDissolved organic matter (DOM) in plateau lakes is a significant component in global DOM pool. Plateau lakes receive stronger natural ultraviolet irradiation relative to plain district, resulting in significantly natural photooxidation of P-DOM, and further affecting its photochemical activity. Considering the strong reactivity, 3P-DOM⁎ is proposed to be a dominant reactive species in the photodegradation of amine and phenolic contaminants in plateau lakes. In addition, ·OH photogeneration ability of P-DOM is great higher than that of the reference DOM with factor of ~ 10, which may act an important role in the photodegradation of refractory organic pollutants in plateau lakes.

Glucomannan isolation from porang (Amorphophallus muelleri Blume) flour using natural deep eutectic solvents and ethanol: A comparative study

Ethanol is a common solvent to isolate glucomannan from porang (Amorphophallus muelleri Blume) flour (NPF). This study investigated the use of natural deep eutectic solvents (NADESs) in glucomannan isolation from NPF. NADESs formed by the hydrogen bond acceptors (choline chloride and betaine) and the hydrogen bond donors (glycerol, 1,2-propanediol, formic acid, and acetic acid) in varying molar ratios of 1:2, 1:3, and 1:4 were characterized to optimize glucomannan isolation. The results showed that higher molar ratios of NADES tended to yield porang glucomannan flour (PGF) with higher glucomannan content and viscosity. The gel of PGF exhibited pseudoplastic behavior. The FTIR spectra indicated that betaine-based NADES removed the acetyl groups from glucomannan chains. The PGF obtained from NADESs with a molar ratio of 1:4 was comparable to those obtained from ethanol with a glucomannan content of 87.34 %–93.28 % and a weight-average molecular weight of 9.12 × 105–1.20 × 106 g/mol.

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.

Optimal and sustainable production of tailored fish protein hydrolysates from tuna canning wastes and discarded blue whiting: Effect of protein molecular weight on chemical and bioactive properties

Thousands tons of discards of blue whiting (BW) and tuna heads (YT) by-products are generated each year in Europe. BW is the species most discarded by European fishing fleet and, in some canning factories, YT are processed for the retrieval of oil rich in omega-3, but producing a huge amount of solid remains and effluents disposal as wastes. The development of optimal and sustainable processes for both substrates is mandatory in order to reach clean solutions under the circular economy precepts. This work focused on the mathematical optimization of the production of tailored fish protein hydrolysates (FPH), from blue whiting and tuna residues, in terms of controlling average molecular weights (Mw) of proteins. For the modeling of the protein depolymerization time-course, a pseudo-mechanistic model was used, which combined a reaction mechanistic equation affected, in the kinetic parameters, by two non-lineal equations (a first-order kinetic and like-Weibull formulae). In all situations, experimental data were accurately simulated by that model achieving R2 values higher than 0.96. The validity of the experimental conditions obtained from modeling were confirmed performing productions of FPH at scale of 5 L-reactor, without pH-control in most of cases, at the different ranges of Mw selected (1–2 kDa, 2–5 kDa and 5–10 kDa). The results showed that FPH from BW with lower Mw led to a remarkable yield of production (12 % w/w of substrate), largest protein contents (77 % w/w of BW hydrolysate), greatest in vitro digestibility (>95 %), highest essential amino acid presence (43 %) and the best antioxidant (DPPH = 62 %) and antihypertensive (IC50-ACE = 80 mg/L) properties. Our results prove that the proposed procedure to produce sustainable FPH, with specific Mw characterisitics, could be extended to other fish waste substrates. Tailored FPH may have the potential to serve as valuable ingredients for functional foods and high-quality aquaculture feed.