High Molecular Weight Research Articles

Constructing Multiscale Fibrous Morphology to Achieve 20% Efficiency Organic Solar Cells by Mixing High and Low Molecular Weight D18.

This study underscores the significance of precisely manipulating the morphology of the active layer in organic solar cells (OSCs). By blending polymer donors of D18 with varying molecular weights, a multiscale interpenetrating fiber network structure within the active layer is successfully created. The introduction of 10% low molecular weight D18 (LW-D18) into high molecular weight D18 (HW-D18) produces MIX-D18, which exhibits an extended exciton diffusion distance and orderly molecular stacking. Devices utilizing MIX-D18 demonstrate superior electron and hole transport, improves exciton dissociation, enhances charge collection efficiency, and reduces trap-assisted recombination compared to the other two materials. Through the use of the nonfullerene acceptor L8-BO, a remarkable power conversion efficiency (PCE) of 20.0% is achieved. This methodology, which integrates the favorable attributes of high and low molecular weight polymers, opens a new avenue for enhancing the performance of OSCs.

The photodegradation of carbamazepine and theophylline in the presence of EOM: The effect of growth period and molecular weight

This study confirmed the discrepancy of growth period and molecular weight (MW) of extracellular organic matter (EOM) on the photodegradation of carbamazepine (CBZ) and theophylline (TF). Comparing to high MW EOM (100 kDa), low MW components (<100 kDa) acted as stronger competitors to photons and free radicals, which restrained the photodegradation of CBZ and TF. 3EOM* played an important role in the degradation of CBZ and TF. Lignin was considered as a new precursor of 3EOM*, which was highly depended on the MW of EOM. The high MW 3EOM* was derived from the CHON compound, while the low MW 3EOM* was derived from the CHONS compound. The results demonstrated that the discrepancy of EOM properties in algae growth period might play a non-negligible influence in the migration and transformation of CECs in the true natural water system.

Insight into carbon structures and pyrolysis behaviors of coal from the 13C CP/MAS NMR spectra

Carbon structures play an important role in the pyrolysis behavior of coal. Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy is a powerful nondestructive technique for characterizing the carbon skeleton structures in coal. In this study, the carbon type distribution, lattice parameters, and chemical bond concentrations of six coal samples with different Vdaf values were investigated using 13C CP/MAS NMR spectra. Typical TGA and Py-GC-MS methods were utilized to obtain information on weight loss and pyrolysis products of the coals. The aromaticity of coal was determined by an adjustment of the apparent area ratio in the 13C CP/MAS NMR spectra, which shows promising potential for predicting key temperatures, characteristic index, and tar quality in coal pyrolysis. Results from the carbon fractions indicated that the total concentrations of chemical bonds in coal are approximately 150 mmol g−1, with more Car−Car and Car−H bonds present in highly mature coal samples, and fewer Cal−Cal, Cal−H, and CO bonds. The breaking behaviors of chemical bonds during coal pyrolysis depend on a combination of temperature and concentration. The breakage of Cal−Cal bond contributes significantly to the pyrolytic weight loss of coal, accompanied by the decrease of Cal−H bonds along with the removal of aliphatic groups. Furthermore, as coal maturity increases, tar from fast pyrolysis contains more polycyclic aromatic hydrocarbons with a higher average molecular weight. The average number of aromatic rings in tar components is notably lower than that of aromatic clusters in coal. These results will contribute to a better understanding of the relationship between coal structure and reactivity, and may provide valuable insights for the efficient and clean utilization of coal.

A quantitative comparison of economic viability, volatile organic compounds, and particle-bound carbon emissions from a diesel engine fueled with biodiesel blends

Despite the environmental advantages of biofuel blends, detailed studies on emissions of polycyclic aromatic hydrocarbons (PAHs), n-alkanes, and particle-bound carbon from diesel engines, particularly when fueled with biodiesel, remain limited. This study addresses these gaps by analyzing biodiesel blends from neem, linseed, and jatropha oils produced via mechanical extraction and assessing their impact on volatile organic compounds and particle-bound carbon emissions in diesel engine. Economic evaluations of production costs, engine modifications, and payback periods are also conducted. The result shows that jatropha biodiesel exhibits a calorific value of 35.7 MJ/kg, while neem biodiesel shows superior oxidative stability due to its low iodine value. Additionally, linseed biodiesel displays favorable cold flow properties due to its high density and cetane value. Compared to D100, the N10 and N30 blend notably reduced high molecular weight PAH emissions by 10.7% and 38.4%, respectively, with the N30 blend achieving a remarkable 76% reduction in formaldehyde emissions. Conversely, the J10 blend increased specific PAHs, while the J30 blend reduced PAHs by 21.3%. Both L10 and L30 blends showed reduced naphthalene emissions, with the J30 blend notably reducing elemental carbon (EC) by 31.4%, although organic carbon (OC) slightly increased. In contrast, the N30 blend decreased both EC and OC emissions, demonstrating a dose-dependent relationship between biodiesel concentration and emissions reduction. Overall, Jatropha biodiesel blends offer the best balance of economic efficiency and emission reductions, resulting in shorter payback periods and lower carcinogenic risks. Neem and linseed blends also provide environmental benefits but with varying economic implications, highlighting the trade-offs between production costs and long-term sustainability.

High Molecular Weight Semicrystalline Substituted Polycyclohexene From Alternating Copolymerization of Butadiene and Methacrylate and Its Ambient Depolymerization.

Cyclohexene cannot be polymerized via ring-opening polymerization under any conditions due to its lack of ring strain. A hypothetical polycyclohexene would therefore have a strong thermodynamic driving force to depolymerize to monomer if a metathesis catalyst were provided while otherwise having thermal and hydrolytic stability under normal conditions because of its hydrocarbon backbone. We envisioned access to this otherwise unattainable family of polymers via the alternating polymerization of a diene and an alkene. Ethyl aluminum chloride was found to promote highly alternating polymerization of butadiene and methacrylate when radically initiated at room temperature, resulting in formal polycyclohexene structures. Ultrahigh molecular weight (up to 1750 kDa) polymers can be synthesized at the decagram scale in high monomer conversions. The resulting presumably atactic copolymers exhibited semicrystallinity, leading to high toughness. In the presence of a small amount of the Grubbs catalyst, the generated polycyclohexene can be fully depolymerized at ambient temperatures into pure constituent cyclohexene. The strategy of using orthogonal chemistry for the polymerization and depolymerization processes allows access to polymer structures with subambient ceiling temperatures without using ultralow temperature synthesis or relying on the monomer-polymer equilibrium.

In vitro and in vivo effects of pectin‐type polysaccharides isolated from crabapples (Malus prunifolia) on inflammatory colitis models

SummaryThe aim of this study was to investigate the anti‐inflammatory effects of polysaccharides extracted from crabapples (Malus prunifolia; MP) in vitro and in vivo. Crabapples were subjected to hot water extraction to obtain MP‐HW, which was further separated into low (MP‐L) and high molecular weight (MW) (crude polysaccharide; MP‐CP) fractions by ethanol precipitation. Based on MW distribution, general composition, component sugars, and Fourier transform infrared spectroscopy, MP‐CP was identified as a pectin‐type polysaccharide rich in galacturonic acid with an MW of 106.2 kDa. MP‐CP inhibited the production and mRNA expression of proinflammatory factors in an IL‐1β‐treated intestinal epithelial cell model. In addition, MP‐CP significantly alleviated the body weight, disease activity index score, colon length, and spleen weight in mice with dextran sulfate sodium (DSS)‐induced colitis. The MP‐CP‐treated group showed effective regulation of the expression of pro‐ and anti‐inflammatory factors and immunoglobulin A than the DSS‐treated group. Haematoxylin and eosin and Alcian blue staining revealed that MP‐CP alleviated inflammatory manifestations and mucin expression in the intestinal lumen. Collectively, pectin‐type polysaccharides isolated from crabapples may be used as a new functional food and pharmaceutical agent for the prevention and treatment of inflammatory colitis.

Insight into response mechanism of short-chain fatty acids to refined microbial transformation order of dissolved organic matter ranked by molecular weight during dry anaerobic digestion.

Dynamic transformation of dissolved organic matter (DOM) contributes to short-chain fatty acids (SCFAs) production during anaerobic digestion. However, the impact of refined transformation of DOM ranked by molecular weight (MW) on SCFAs has never been investigated. Results indicated that DOM conversion order was 3500-7000 Da>(MW>14000 Da) > 7000-4000 Da during hydrolysis stage, while it was independent of their MW in acidogenesis phase and followed a low to high MW order during methanogenesis stage. Proteins-like DOMs with different MW were closely related to SCFAs. Eight groups of microorganisms (e.g., Bacillus and Caldicoprobacter) responsible for the conversion of proteins-like DOMs to SCFAs. The possible routes linking environmental properties to microorganisms-proteins-like DOMs-SCFAs connections were constructed. Microbial activity modifications by regulating moisture, pH, NO3--N and NH4+-N can expedite the conversion of proteins-like DOMs to SCFAs. The study emphasizes the importance of MW-classification-based biotransformation of organic waste, offering a potential strategy to enhance anaerobic digestion performance.

Effect of different yeast-derived products on a red wine polyphenolic composition: influence of the wine age

The name “yeast-derived products” (YDPs) refers to different preparations obtained from yeast cells through various processes. These YDPs have different characteristics and applications in oenology, one being the improvement of the sensory properties of wines. This work aimed to identify the impact of YDPs obtained from different yeast strains and through different downstream inactivation processes on polyphenols in a red wine at different aging times. At an oenological dosage of 40 mg/L in a young wine, the addition of YDPs resulted in a variable decrease in total polyphenol index (TPI) (2 to 9 % depending on the YDPs) and a significant decrease in the precipitation of tannins (15 to 50 %) and high molecular weight (HMW) pigments (19 to 85 %) were obtained in the BSA assay, thus demonstrating the involvement of tannins and HMW pigments in interactions with the studied yeast-derived products. Pigment involvement led to a change in colour indices (L*a*b* and colour intensity), but in most cases this change was not visible to the human eye at the oenological dosage tested (40 mg/L). Experiments conducted on both the young wine and the same wine aged for three months using the same yeast-derived products, dosages and aging conditions revealed the influence of the chemical evolution of polyphenols on their interactions with YDPs. The significant variation observed in this study highlights the critical role of yeast selection and the yeast fragmentation downstream process on YDP efficiency. The high-pressure homogenisation (HPH) yeast fractions were shown to be more efficient than the corresponding whole yeast cells. Increasing the contact surface area between yeast cell constituents and wine matrix enabled by the HPH process may be a key strategy for enhancing the effectiveness of yeast derivatives in red wines, and in aged wines in particular, in which the phenolic compounds underwent changes and exhibited less interaction with the studied yeast-derived products. This research has contributed to increasing our understanding of and the potential for apply these processing aids in oenology.

Extraction, characterization, and neuroprotective effects of polysaccharides the stems of Panax ginseng C. A. Meyer by three different solvents (water, acid, alkali)

The purpose of this study was to optimize the extraction process of polysaccharides from the stems of Panax ginseng C. A. Meyer using different solvents (water, acid and alkali), and investigate their protective effects on PC12 cells against Amyloid-β1–42 (Aβ1–42)-induced cell apoptosis. Three polysaccharides (W-GSP, Ac-GSP and Al-GSP) were prepared and optimized: liquid to material ratio 27:1 mL/g, extraction temperature 89°C, extraction time 2.9 h and 0.3 mol/L HCl/NaOH. The results of characterization indicated that the monosaccharides of W-GSP (703.80 kDa), Ac-GSP (641.38 kDa) and Al-GSP (457.04 kDa) all composed mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, xylose and arabinose with different molar ratios. Interestingly, W-GSP possessed a lower uronic acid, higher molecular weight, rougher surface and poorer thermal stability, whereby W-GSP exhibited a protective effect against Aβ1–42-induced apoptosis in PC12 cells by mediating the JNK signaling pathway, restoring the mitochondrial membrane potential and reducing intracellular ROS levels. This study should be provided the theoretical basis for the study and exploitation of polysaccharides from the stems of Panax ginseng C. A. Meyer.

Characterisation, antibacterial activity, and prebiotic potential of dried Hermetia illucens L. larvae and of their fractions

Abstract In this study, black soldier fly (BSF) dried larvae were fractionated into their defatted, lipid, protein, and chitin-rich fractions. The samples were then characterised in terms of proximate composition, analysis of amino acids, analysis of the molecular weight distribution of proteins via gel electrophoresis, and fatty acids analysis of the lipid fraction. The antibacterial activity of all fractions was determined against Escherichia coli F4 and Streptococcus suis, two common swine pathogens. Finally, the prebiotic activity of the whole larvae and of their protein isolate and chitin-rich pellet was determined for Limosilactobacillus reuteri, a naturally occurring species in the gastro-intestinal tract of the pig. The results on amino acid profile showed that the protein extraction method used was not fully effective in cleaving chitin-bound proteins, as expected, as the true protein content of the chitin-rich sample was 48.5%. This was in accordance with the SDS-PAGE analysis, where the molecular weight distribution of proteins in the protein isolate sample did not show band at higher molecular weight, which were instead present in the chitin-rich sample. The analysis of fatty acid (FA) profile showed that lauric acid was the most abundant FA, in accordance with the literature. The results on microbiological analyses highlighted how all nitrogen-containing samples showed antibacterial activity against E. coli, the highest being the defatted fraction at 1% with a decrease of −0.77 log CFU/mL, while only the lipid fraction against S. suis (−0.48 log CFU/mL at 1%). All tested samples showed prebiotic activity for L. reuteri, but it was noticed that the increase in chitin concentration resulted in the decrease of the prebiotic effect. By combining the results of both antibacterial and prebiotic tests, it could be inferred that chitin might be considered as an antibacterial compound.

Aromatic (Co)polycarbonates bearing pendant norbornenyl groups: Synthesis, characterization and post-polymerization modification

A homo- and three co-polycarbonates (PC-NBs) bearing pendant norbornenyl groups were synthesized via solution polycondensation of triphosgene with 4, 4'-(bicyclo (2.2.1) hept-5-en-2 yl methylene) bis (2-methoxyphenol) (BPA-NB) or various mol % compositions of BPA-NB and bisphenol-A, respectively. 1H-NMR spectroscopy confirmed the chemical structure and composition of PC-NBs. Inherent viscosity and number-average molecular weight (Mn) values of PC-NBs were in the range 0.44 – 0.64 dL g−1 and 21,800 – 34,100 g mol−1, respectively, indicating the formation of polymers of medium to reasonably high molecular weights. Tough, transparent, and flexible films of PC-NBs could be cast from chloroform solution. X-Ray diffraction studies indicated the amorphous nature of PC-NBs. Glass transition temperature (Tg) values, determined by DSC analysis, of PC-NBs were in the range 154 – 175°C and Tg values increased with the increase in mol % of BPA-NB. The post-polymerization modification of a representative PC-NB was demonstrated using 3,6-diphenyl-1,2,4,5-tetrazine via tetrazine-ene reaction.

The Hydrogen Bonding in the Hard Domains of the Siloxane Polyurea Copolymer Elastomers

For probing the structure–property relationships of the polyurea elastomers, we synthesize the siloxane polyurea copolymer elastomer by using two aminopropyl-terminated polysiloxane monomers with low and high number-average molecular weight (Mn), i.e., L-30D and H-130D. To study the influence of the copolymer structures on the film properties, these films are analyzed to obtain the tensile performance, UV-vis spectra, cross-sectional topographies, and glass transition temperature (Tg). The two synthetic thermoplastic elastomer films are characterized by transparency, ductility, and the Tg of the hard domains, depending on the reacting compositions. Furthermore, the film elasticity behavior is studied by the strain recovery and cyclic tensile test, and then, the linear fitting of the tensile data is used to describe the film elasticity based on the Mooney–Rivlin model. Moreover, the temperature-dependent infrared (IR) spectra during heating and cooling are conducted to study the strength and recovery rate of the hydrogen bonding, respectively, and their influence on the film performance is further analyzed; the calculated Mn of the hard segment chains is correlated to the macroscopic recovery rate of the hydrogen bonding. These results can add deep insight to the structure–property relationships of the siloxane polyurea copolymer.

Molecular Mechanism of Egg White Protein for Strengthening the Cross‐Linking Properties of Heat‐Induced Wheat Gluten Gel

AbstractThe chemical interaction between egg white protein (EWP) and wheat gluten (WG) is significantly influenced by the amount of EWP added. Therefore, the effects of EWP addition on the gelling properties and chemical interactions of heat‐induced WG–EWP gels are thoroughly examined. The results demonstrate that the enhancement in gel strength of WG–EWP gels is positively correlated with the amount of EWP added. EWP addition improves protein–protein interactions by reducing the freedom of water. The enhanced aggregation between WG and EWP is likely due to a decrease in surface hydrophobicity and an increase in β‐sheet content. EWP enhances cross‐linking with low molecular weight glutenin subunit (LMW‐GS), high molecular weight glutenin subunit (HMW‐GS), and gliadin (Gli). Specifically, EWP primarily cross‐links with ω‐, α‐, and γ‐Glis through S–S bonds and interacts with GS through hydrophobic interactions and S–S bonds. This study provides a theoretical foundation for improving the WG network structure in wheat‐based food production.

Bimolecular Sandwich Aggregates of Porphyrin Nanorings.

Extended π-systems often form supramolecular aggregates, drastically changing their optical and electronic properties. However, aggregation processes can be difficult to characterize or predict. Here, we show that butadiyne-linked 8- and 12-porphyrin nanorings form stable and well-defined bimolecular aggregates with remarkably sharp NMR spectra, despite their dynamic structures and high molecular weights (12.7 to 26.0 kDa). Pyridine breaks up the aggregates into their constituent rings, which are in slow exchange with the aggregates on the NMR time scale. All the aggregates have the same general two-layer sandwich structure, as deduced from NMR spectroscopy experiments, including 1H DOSY, 1H-1H COSY, TOCSY, NOESY, and 1H-13C HSQC. This structure was confirmed by analysis of residual dipolar couplings from 13C-coupled 1H-13C HSQC experiments on one of the 12-ring aggregates. Variable-temperature NMR spectroscopy revealed an internal ring-on-ring rotation process by which two π-π stacked conformers interconvert via a staggered conformation. A slower dynamic process, involving rotation of individual porphyrin units, was also detected by exchange spectroscopy in the 8-ring aggregates, implying partial disaggregation and reassociation. Molecular dynamics simulations indicate that the 8-ring aggregates are bowl-shaped and highly fluxional, compared to the 12-ring aggregates, which are cylindrical. This work demonstrates that large π-systems can form surprisingly well-defined aggregates and may inspire the design of other noncovalent assemblies.

Insights on influence of polymer molecular weight on gas sorption, transport and plasticization in glassy 6FDA-DAM polyimide membranes

It is well-known that spinning of defect-free asymmetric polyimide hollow fibers is promoted by using high polymer molecular weight. On the other hand, effects of polymer molecular weight on microstructure and separation performance of dense film 6FDA-based polyimide membranes relevant to sheath layers of composite membranes are less well-explored. In this work, gas sorption, diffusion and permeation of CO2, N2 and CH4 for 6FDA-DAM dense films are considered for 45 kDa and 176 kDa weight average molecular weights. Such molecular weights are relevant for practical hollow fiber spinning of membranes. Earlier results for polystyrene samples show similar trends in dual mode sorption model results like those noted here for the 6FDA-DAM polyimide case; however, effects on permeation like those considered here were not addressed for the polystyrene case. Here we also address actual pure and mixed gas CO2 and CH4 permeation and show higher free volumes, higher gas permeability but lower 50:50 CO2/CH4 selectivity associated with the higher molecular weight sample. Analysis using the self-consistent dual-mode sorption and transport models help understand the observed trends. Our results suggest denser packing of polymer segments exists in the Henry's law environment of the low molecular weight sample. Moreover, the higher polymer segmental packing in the Henry's law environment suppresses CO2 plasticization with a dual-mode microstructure controlling separation performance and plasticization behavior for this important member of the 6FDA polyimide family. We show evidence of effects of charge transfer complexes as possible main features in these trends. These dense film results help guide future work on dense sheath layers on composite hollow fiber membranes.

A membrane fouling control strategy based on a combination of pre-treatment mitigation and in-situ membrane surface regulation using a composite coagulant

Ultrafiltration technology (UF) is efficient in surface water treatment, but its development and widespread application are limited by membrane fouling. Herein, an efficient and stable polymerized ferric titanium coagulant (PFTC) was synthesized and used as a UF pretreatment agent in actual lake water treatment. The control mechanism of PFTC on membrane fouling was investigated from the perspective of organic removal efficiency and in-situ membrane surface regulation. PFTC demonstrated a remarkable affinity for soluble metabolic intermediates and hydrophilic proteins through complexation and hydrogen bonding force, achieving removal efficiencies of 66.4% for UV254 and 81.3% for DOC, respectively. The hydrophilic pollutants with high molecular weight and non-saturated structure could be preferentially removed by PFTC due to its diverse hydrolysates including positively charged Fe-based hydrolysates, amorphous Ti-based hydrolysates, and highly polymerized Fe-Ti copolymers. The flocs generated by PFTC exhibited strong hydrophilicity, allowing for the formation of a loose porous cake layer on the ultrafiltration membrane, which acted as a hydrophilic layer to enhance the anti-fouling performance of ultrafiltration membrane. With its dual function of contaminant removal and in-situ membrane surface regulation, PFTC alleviated 98.9% of membrane fouling. This study provides new insights into membrane fouling control by coagulation pretreatment and efficient treatment of surface water.

Determination of aconitum alkaloids in acute poisoning case by electromembrane extraction

In this work, electromembrane extraction (EME) was used for the first time to separate aconitine (AC), mesaconitine (Mes-AC) and hypaconitine (Hyp-AC) from biological samples and Chinese herbal medicines. Efficient EME of polar and high molecular weight aconitine alkaloids from different sample matrices was achieved with the solvent of 1-ethyl-2-nitrobenzene (ENB). Under the optimal EME conditions, EME provided recoveries for all targets in the range of 72%–74 %, 85%–103 % and 92%–94 % for whole blood, urine and aqueous samples. The proposed EME systems combined with LC-MS/MS and HPLC-UV were evaluated using different sample matrices, and the methods displayed satisfactory analytical characteristic including negligible matrix effect. The LOD and LOQ of AC, Mes-AC, and Hyp-AC by EME-LC-MS/MS were in the range of 0.002–0.068 ng/mL and 0.005–0.228 ng/mL respectively. The LOD and LOQ of AC, Mes-AC, and Hyp-AC by EME-HPLC-UV were in the range of 0.06–0.26 μg/mL and 0.20–0.86 μg/mL, respectively. The coefficient of determination, R2-value was ≥0.9926 for all cases, and the accuracy in the linear ranges was in the range of 91%–111 %. Finally, the method was successfully applied for the qualitative and quantitative analysis of AC and Mes-AC in the whole blood and herbal medicine dreg samples from an actual forensic case, and poisoning by aconitum alkaloids was identified as the cause of death. Therefore, we believe that EME could be a powerful tool to identify poisoning, and EME has great potential for efficient separation of polar and high molecular weight substances. These are of great importance in the fields of but not limited to forensic science, Traditional Chinese Medicine and clinics.

Dissolution of denim waste in N-methyl morpholine-N-oxide monohydrate for fabrication of regenerated cellulosic film: Experimental and simulation study

Despite the significant amount of denim waste and its potential as a cellulose source, its use has been neglected. This study uses N-methyl morpholine-N-oxide, an eco-friendly solvent, to dissolve denim (including 100 % cotton) and create a denim film. Achieving a 10 % denim record solubility, a cellulosic film was also fabricated for comparison. Characterisation techniques were applied, and molecular dynamics simulations explored intramolecular interactions and the influence of indigo dye on dissolution process. FTIR spectra indicated no chemical reactions during dissolution and regeneration, though a shift in OH stretching suggested a change in crystallinity, confirmed by XRD results showing decreased crystallinity and a structural shift from cellulose I to cellulose II. 13C NMR analysis revealed disruptions in interchain hydrogen bonds after regeneration. TGA results showed lower decomposition temperatures for both films compared to the powders. Testing mechanical properties showed the denim film had higher elongation at break but lower tensile strength than the cellulose film. MD simulations indicated indigo dye did not significantly affect fundamental interactions but decreased denim solubility by reducing the diffusion coefficient. Rheological tests supported the simulation results, showing higher viscosity and molecular weight for the denim solution compared to cellulose.

Enhanced human activities since 20th century in pearl river delta, southern China: Evidence from high-resolution sedimentary records of polycyclic aromatic hydrocarbons and synthetic musks

To understand the environmental impact of anthropogenic activities, the high-resolution temporal and compositional variations of polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs, and synthetic musks, related to human activities were investigated in a sediment core taken from the Pearl River Estuary, southern China. The temporal trend of the target compounds was evidence of the considerable impact of anthropogenic activities in the Pearl River Delta. Two significant increases of the target compounds levels in the sediment core were aligned with two nodes of key periods of economic development in China, namely, the foundation of People's Republic of China (1950s) and China's accession to the World Trade Organization (2000s). Subsequently, the significant decline of the target compounds in sediments from the 2010s indicated the successful regulation of pollutant discharges and pollution control measures. The increase in the contribution of higher molecular weight PAHs suggested a potential transition from agricultural activities to industrial activities.

Evaluation of morphology, physical and mechanical properties of hyaluronic acid matrices of various molecular weights by atomic force microscopy

Using atomic force microscopy the morphology of 1 and 2 % sodium hyaluronate solutions matrix with low molecular weight (LM) and high molecular weight (HM) hyaluronic acid (HA) fabricated by bioenzymatic synthesis was evaluated. The presence of a proteoglycan aggregate with processes of the core protein in the absence of sulfated glycosaminoglycans was established. The effect of irradiation with a light flux on the ordering of the HA matrix was observed. Intermolecular consolidation of high molecular HA was established. The elastic modulus of the matrix with LM and HM HA has also been determined.