High Molecular Weight Components Research Articles

Hydrogeochemical dynamics under saltwater-freshwater mixing in a mangrove wetland over tidal cycles

Seawater and groundwater interactions shape the hydrogeochemical profile of mangrove aquifers, revealing how biogeochemical processes adapt to saline-freshwater mixing via the fluctuating patterns of key hydrochemical indicators and primary biogenic elements. This study, utilizing a multi-level monitoring profile spanning the entire submerged aquifer within a mangrove wetland, analyzed the spatiotemporal dynamics of DO, ORP, pH, alkalinity and biogenic elements (C, N, S). The results revealed that among the basic hydrochemical parameters, total alkalinity showed the most stable spatiotemporal distribution and was positively correlated with salinity. pH demonstrated a significant negative correlation with salinity, whereas the correlations of ORP and DO with salinity were not substantial. The discharge of terrestrial freshwater into the mangrove wetland is marked by hydrogeochemical reactions favoring the input of Mg2+ and DIC, with potential iron mineral precipitation within the aquifer. Spatial distribution of biogenic elements in the groundwater showed no apparent pattern across sampling periods. DOC concentrations ranged from 0.3 to 1.3 mmol/L. Three components of dissolved organic matter were identified using three-dimensional fluorescence spectroscopy, with high molecular weight components (C1 + C2) accounting for an average of 47 to 73 %. Both elevated DOC concentrations and high molecular weight component ratios were primarily found in shallow layers of dense mangrove areas, decreasing with depth. Concentrations of ammonia, nitrite, and nitrate varied dynamically, reflecting active biochemical processes in the shallow to mid-layers of the aquifer. Furthermore, sulfate and sulfide concentrations, ranging from 0 to 26 mmol/L and 0.4 to 576.8 μmol/L, respectively, underscore the interplay of biogeochemical reactions, especially sulfate reduction. These findings highlight valuable insights into the complex biogeochemical processes within mangrove aquifers and provide theoretical guidance for protecting the ecological health of mangrove wetlands.

Effect of pre-oxidation on the rate of formation of sulfur-containing aromatic compounds during vacuum gas oil thermal cracking

It was shown that oxidation followed by heat treatment is an effective method for desulfurization of vacuum gas oil. Patterns of changes in the quantitative content of the thiophene series compounds in liquid cracking products of vacuum gas oil and liquid cracking products of pre-oxidized vacuum gas oil are described. A mixture of hydrogen peroxide and formic acid (molar ratio 3:4) was used as the oxidation system. The hypothetical mechanism for the formation of thiophene, benzo- and dibenzothiophene and their homologues from high-molecular weight components of the initial vacuum gas oil and its oxidation products is proposed. Presumably, main path of formation considerate compounds is thermal decomposition of high-molecular weight sulfur-containing components. On the basis of IR spectroscopy and structure-group analysis data, the averaged structures of such components were constructed. The influence of pre-oxidation and its conditions on the value of the rate constants for the formation of thiophene, benzo- and dibenzothiophene and their homologues during thermal cracking of initial and oxidized vacuum gas oils is studied.

Discrete molecular weight strategy modulates hydrogen bonding‐induced crystallization and chain orientation for melt‐spun high‐strength polyamide fibers

AbstractHydrogen bonding is the prerequisite for polyamide fibers to have better stress–strain behavior. It affects the crystal structure of polyamide fibers, such as orientation and periodic arrangement. To illustrate the effect of intermolecular hydrogen bonding on fiber orientation structure and macroscopic mechanical properties, this work uses conventional polyamide resin doped with high molecular weight components to construct polymer compounds with discrete distribution characteristics. By analyzing the changes in intermolecular hydrogen bonds, melt rheological properties, non‐isothermal crystallization behaviors, the impact of hydrogen bonds on the crystal structure and orientation structure and thus on the fiber strength was clarified. The doping of high molecular weight components can make the compound form more hydrogen bonds and inhibit the relaxation of molecular chains through entanglement, thereby promoting melt non‐isothermal crystallization process and increasing complex viscosity η* and storage mode G'. 1D and 2D wide‐angle and small‐angle X‐ray scattering show that doping components reduce crystal size of α1(200) and α2(002, 202) planes from 4.19 to 3.47 nm and 5.88 to 4.96 nm, resulting in a denser long‐period structure. Through the strategy of this work, polyamide 6 fibers' tensile strength is effectively improved by18%, and the mechanical properties are significantly improved.Highlights High‐strength polyamide compound fibers were prepared. Discretely distributed compounds are achieved. Discretely distributed molecular weight enabled hydrogen bonding regulation. Hydrogen bonding‐induced compound fiber crystal structure. Multiple external fields induced crystallization and orientation structures.

The fate of various organic compounds including pharmaceuticals in the treatment of landfill leachate and anaerobic digestate using deammonification

Studies focusing on the fate of organic compounds specifically recalcitrant organics and pharmaceuticals in a deammonification plant are scarce. This study downscaled a full-scale deammonification plant, which was being operated with the same wastewater streams of this study and evaluated for the first time the fate of different fractions of organic compounds in deammonification process along with the removal of nitrogenous compounds. Organic compounds in the feed and effluent were analyzed and their changes in the deammonification process were characterized. The results demonstrate that deammonification achieved over 90% of ammonium removal. COD monitoring revealed that around 11% of COD was reduced during the process mainly due to aerobic COD degradation and heterotrophic denitrifying bacteria. Analysis of the organic fractions revealed that high molecular weight components (around 11 kDa) are susceptible to removal and their concentrations tend to decrease in the reactor. Concentrations of humic substances, specifically fulvic acid-like substances, were reduced. Tracking nine different pharmaceutical residues revealed that morphine and cotinine were completely removed, while pregabalin and oxazepam which are known to be highly recalcitrant were more than 60% removed. The research finding can help in optimizing treatment processes by revealing the fate of different organic compounds, especially pharmaceuticals, within the deammonification process, thereby contributing to better effluent quality, regulatory compliance, and environmental protection.

The impacts of pullulan soaking on radish seed germination and seedling growth under salt stress.

Pullulan can not only provide a source of organic carbon but also has excellent properties. However, current research is mostly limited to the physical properties of the high-molecular-weight components of pullulan, and little is known about the application of its low-molecular-weight components. This study was designed to explore the impact of presoaking of radish seeds in a pullulan solution on seed germination and subsequent seedling growth under salt stress conditions. Pullulan soaking was found to enhance the germination rates of radish seeds subjected to salt stress, while also enhancing the aboveground growth of radish seedlings. Pullulan soaking resulted in increases in chlorophyll, soluble protein, and soluble sugar concentrations in the leaves of these seedlings, together with greater peroxidase activity and root activity as well as decreases in Na+ and malondialdehyde concentrations. This provides an important reference for the application of pullulan in plant protection.

A cluster approach to rationalize shear thinning: Application to polymer solutions and suspension fluids

This paper calculates for liquid mixtures of high and low molecular weight components, how many solute molecules flow on the average conjointly. The application of the approach to solutions of poly(dimethyl siloxane) in its pentamer, to suspensions of gibbsite (Al(OH)3) in dimethyl sulfoxide, and to human blood testifies that the approach is applicable without restrictions regarding the chemical nature of the high molecular weight compound. The shear thinning of the systems under investigation can be understood in terms of a reduction of the shear-overlap parameter Σ, where the generalized intrinsic viscosity {η} constitutes the central property governing the composition and shear rate dependence of the viscosities. Furthermore, the present analysis demonstrates that intrinsic viscosities can be determined for all solutes and that they decrease with rising shear rates according to a Boltzmann sigmoid for the systems DMS5/PDMS and blood. The comparison of the hydrodynamic specific volumes of the solutes (i.e., of [η]) with the corresponding specific volumes in the pure state leads to the conclusion that solutes that cannot interpenetrate carry a considerable amount of solvent piggyback with them when flowing. In addition to the pure description of the observations, the approach was able to point to new phenomena, e.g., the solidification of the gibbsite suspensions beyond a characteristic solute concentration, which shifts to higher values with increasing shear rates. Because of its general nature, the present approach should become helpful, above all in the areas of technology (reactions in flowing systems) and health (rheology of blood).

Understanding the complexity of Tityus serrulatus venom: A focus on high molecular weight components.

Tityus serrulatus scorpion is responsible for a significant number of envenomings in Brazil, ranging from mild to severe, and in some cases, leading to fatalities. While supportive care is the primary treatment modality, moderate and severe cases require antivenom administration despite potential limitations and adverse effects. The remarkable proliferation of T. serrulatus scorpions, attributed to their biology and asexual reproduction, contributes to a high incidence of envenomation. T. serrulatus scorpion venom predominantly consists of short proteins acting as neurotoxins (α and β), that primarily target ion channels. Nevertheless, high molecular weight compounds, including metalloproteases, serine proteases, phospholipases, and hyaluronidases, are also present in the venom. These compounds play a crucial role in envenomation, influencing the severity of symptoms and the spread of venom. This review endeavors to comprehensively understand the T. serrulatus scorpion venom by elucidating the primary high molecular weight compounds and exploring their potential contributions to envenomation. Understanding these compounds' mechanisms of action can aid in developing more effective treatments and prevention strategies, ultimately mitigating the impact of scorpion envenomation on public health in Brazil.

Modeling the competition between phase separation and polymerization under explicit polydispersity.

The dynamics of phase separation for polymer blends is important in determining the final morphology and properties of polymer materials; in practical applications, this phase separation can be controlled by coupling to polymerization reaction kinetics via a process called 'polymerization-induced phase separation'. We develop a phase-field model for a polymer melt blend using a polymerizing Cahn-Hilliard (pCH) formalism to understand the fundamental processes underlying phase separation behavior of a mixture of two species independently undergoing linear step-growth polymerization. In our method, we explicitly model polydispersity in these systems to consider different molecular-weight components that will diffuse at different rates. We first show that this pCH model predicts results consistent with the Carothers predictions for step-growth polymerization kinetics, the Flory-Huggins theory of polymer mixing, and the classical predictions of spinodal decomposition in symmetric polymer blends. The model is then used to characterize (i) the competition between phase separation dynamics and polymerization kinetics, and (ii) the effect of unequal reaction rates between species. For large incompatibility between the species (i.e. high χ), our pCH model demonstrates that the strength for phase separation directly corresponds to the kinetics of phase separation. We find that increasing the reaction rate k̃, first induces faster phase separation but this trend reverses as we further increase k̃ due to the competition between molecular diffusion and polymerization. In this case, phase separation is delayed for faster polymerization rates due to the rapid accumulation of slow-moving, high molecular weight components.

Effect of thermal-oxidative and mechanical degradation of recycled LDPE on foaming

In this study, we investigated the effect of recycling process on the molecular structure, viscoelasticity and foaming behavior of low density polyethylene (LDPE). A series of LDPE samples with different recycling process was prepared by multiple extrusion using a twin-screw extruder. The molecular weight distribution (MWD) was characterized by gel permeation chromatography (GPC). Wider MWD indicated the generation of higher molecular weight products. Small-amplitude oscillation rheology showed reduced loss factors, indicating that the chain entanglement was more difficult to relax. Moreover, nonlinear viscoelasticity was investigated using elongational rheology and molecular stress function (MSF) model. The results showed a steeper strain hardening exhibited in recycled LDPE. The correlated parameter β in the MSF model indicated that the recycling did not significantly change the branches regularity in LDPE, while the increasing [Formula: see text], the other correlated parameter, indicated that the chain entanglement was enhanced, which was corresponded to the improvement of high molecular weight component. The foaming results revealed that the recycled LDPE had finer cellular structure and higher nucleation density. Moreover, despite adding PP and active CaCO3 to simulate the impurities, the foamability loss of these mixed samples was well restricted and still valuable. Recycled LDPE is instead better than its corresponding virgin one in foaming performance, exhibiting the application potential for further developments.

A Comparative Study on the Removal of Microcystis and Cylindrospermopsis Blooms in Two Lakes by Flocculation–Filtration Treatment

Dianchi Lake and Yilong Lake, two prominent plateau lakes in Yunnan Province, China, have suffered from Microcystis and Cylindrospermopsis blooms for decades. While cyanobacteria harvest boats utilizing cationic polyacrylamide (CPAM) flocculation and screen filtration have been proven effective for harvesting Microcystis biomass in Dianchi Lake, they struggle against Cylindrospermopsis blooms in Yilong Lake. This study systematically compared the removal of Microcystis and Cylindrospermopsis blooms using flocculation–filtration treatment, aiming to identify key factors influencing flocculation and propose enhancements to improve treatment efficiency for Cylindrospermopsis blooms. The reduction of turbidity, OD680, biovolume and phytoplankton density all revealed significantly better treatment efficiency for Microcystis blooms compared to Cylindrospermopsis blooms. In Dianchi Lake, 1 mg/L CPAM achieved a 95% turbidity reduction, while in Yilong Lake, even with 4.0 mg/L CPAM, the removal efficiency remained below 90%. Post-treatment, Dianchi Lake’s water quality showed substantial improvements, including over 50% reductions in total nitrogen, total phosphorus, permanganate index, and chemical oxygen demand. Conversely, nutrient level reductions were limited in Yilong Lake’s treated water. The average molecular weight of dissolved organic matters (DOM) in Yilong Lake was notably smaller than in Dianchi Lake. The treatment selectively removed high molecular weight, microbial-sourced, and protein-like DOM components, leading to a decrease in average molecular weight and an increase in humification index (HIX) in both lakes. Excessive humic matters in the water of Yilong Lake was found to hamper algae flocculation significantly. Introducing additional acidic polysaccharides or oxidants emerged as potential strategies to enhance Yilong Lake’s treatment efficiency.

High molecular weight bimodal polyethylene elastomers using N,N'-nickel catalysts appended with methoxy and trifluoromethoxy functionality

Polyolefinic materials displaying bimodal molecular weight distributions are of interest since they can potentially provide mechanical toughness from the high molecular weight component without losing processability on account of the low molecular weight component. With this in mind, a series of nickel(II) complexes, [1-[2,6-{(4-MeOC6H4)2CH}2–4-(F3CO)C6H2N]-2-(ArN)C2C10H6]NiBr2 (Ar = 2,4-Me2C6H3Ni1, 2,6-Et2C6H3Ni2, 2,6-iPr2C6H3Ni3, 2,4,6-Me3C6H2, Ni4, 2,6-Et2-4-MeC6H2Ni5, 2,6-Me2C6H3Ni6) have been synthesized and have shown, following treatment with MMAO or Et2AlCl, excellent activity for the polymerization of ethylene (up to 19.87 × 106 g (PE) mol−1 for Ni4/Et2AlCl) generating high molecular weight branched polyethylene. More importantly, the elastomeric material produced using Et2AlCl as activator displays bimodal characteristics as well as low crystallinity and a medium to high branching density. By contrast, the material prepared using MMAO was more unimodal and showed higher crystallinity and lower branching density. Stress–strain and stress–strain recovery tests performed on the bimodal PE’s revealed a range of tensile properties with a sample prepared using Ni5/Et2AlCl combining both high tensile strength and high fracture strength (σ = 20.3 MPa, ε = 892.0 %). Conversely, a PE sample prepared using Ni4/Et2AlCl showed the highest elastic recovery with a stress relaxation (SR) value of 67.6 %. Besides branching analysis, molecular weight determinations and mechanical tests on the polymers, all nickel complexes and precursor 1,2-bis(arylimino)acenaphthenes, have been characterized by a combination of spectroscopic techniques, elemental analysis and in the cases of Ni1(OH2) and Ni4 by single crystal X-ray diffraction. A theory is also proposed to explain the observed bimodality.

Designing gelatin microgels by moderate transglutaminase crosslinking: Improvement in interface properties

In this study, gelatin microgels with various crosslinking degrees were facilely fabricated through moderate transglutaminase (TGase) crosslinking. The influences of crosslinking degree on the surface and interface properties of gelatin microgels were investigated. Furthermore, the influence on the stability of gelatin microgels emulsions was also explored. The crosslinking degree of gelatin microgels was gradually increased from 1.85% to 12.25% and positively correlated with the addition amount of TGase. With the increase of crosslinking degree, the high molecular weight components in gelatin microgels increased, and the wettability (32°–81°) and surface hydrophobicity of gelatin microgels gradually increased. The interfacial protein content also increased with the increase of crosslinking degree and reached equilibrium as the crosslinking degree exceeded 6.85%. The results of interfacial dynamic adsorption and interfacial dilatational viscoelasticity demonstrated the formation of a dense and strong interfacial structure, especially at relatively higher crosslinking degree (>6.85%). The liquid chromatography-tandem mass spectrometry (LC-MS/MS) results confirmed that TGase crosslinking increased the crosslinking between α2 chain in gelatin molecular chains, thus enhancing interfacial interaction and regulating interface microstructure. TGase crosslinking effectively improved the physical stabilities of gelatin microgel emulsions, suggesting a dominant contribution of the adjusted interface properties of gelatin microgels by moderate TGase crosslinking.

Evaluation of proteolytic activity and serine proteases distribution in plasma from patients with bladder cancer.

Bladder cancer (BC) is an aggressive disease with a poor prognosis. A bladder tumor, like other malignant neoplasms, is characterized by the presence of both cancer cells and stromal cells which secrete cytokines, chemokines, growth factors, and proteolytic enzymes. One such class of proteolytic enzymes are serine proteases, which take part in the tumor microenvironment formation via supporting and contributing to tumor progression. This study aims to evaluate the proteolytic activity and serine protease contribution in plasma from BC patients. The research involved patients of Alexandrovsky city clinical hospital aged 52-76 with transitional cell carcinoma of the bladder. All examined patients were divided into five groups: the control group included conditionally healthy donors, while other patients were grouped according to their tumor stage (I, II, III and IV). Plasma plasminogen levels were determined by enzyme-linked immunosorbent assay, and the potential activity was measured by chromogenic plasminogen assay. Serine proteases fractions were obtained by the affinity chromatography method, and enzyme concentration in the selected fractions were determined by the Bradford method. Serine proteases distribution was investigated by electrophoresis in a polyacrylamide gel. It was determined that the concentration, potential activity of plasminogen, and the total amount of serine proteases in plasma from BC patients were greater than the values of the corresponding indicators in healthy donors. This could be one of the factors contributing to increased proteolysis seen in the process of carcinogenesis. Plasminogen concentration in BC patients with stage IV disease; however, displayed a tendency to be reduced compared to earlier stages, and the potential activity of plasminogen was significantly lower in patients with stages III - IV BC. Futhermore, a tumor stage specific gradual decline in the serine protease plasma content was shown. The results of electrophoretic analysis established a significant diminishment in the percentage of high molecular weight components (under non-reducing conditions) and their complete disappearance (under reducing conditions) in plasma serine protease fractions from BC patients. A decline in the percentage of heavy and light plasmin chains in BC patients was also observed. Additionally, a rise in the degraded forms of plasminogen/plasmin content was seen in BC samples, as well as the presence of fractions corresponding to trypsin and NE (under non-reducing conditions) that were absent in the control samples. The results indicate significant changes in the proteolytic activity of plasma, from BC patients when compared to healthy controls, which is accompanied by alterations in serine protease distribution caused by tumor microenvironment pecularlities at the different stages of oncopathology.

Characterization of balsam sulfide via pyrolysis-gas chromatography-mass spectrometry/sulfur chemiluminescence detection and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Balsam sulfide, produced by the reaction of turpentine/rosin and sulfur, has been used as one of the raw materials of liquid gold to decorate ceramics and tableware with thin gold film for more than 100years. The characterization of balsam sulfide is still insufficient because of its compositional complexity. In this study, balsam sulfide was characterized using pyrolysis-gas chromatography (Py-GC)-mass spectrometry (MS) and Py-GC with sulfur chemiluminescence detection (SCD) as well as matrix-assisted laser desorption/ionization time-of-flight MS (MALDI-TOFMS). Py-GC-MS/SCD analyses of balsam sulfide and its model samples revealed that the low molecular weight reaction products were mainly composed of compounds of one α-pinene unit reacted with 1-3 sulfur atoms. In the analysis of the high molecular weight components by MALDI-TOFMS, the products of two or three α-pinene units crosslinked by sulfur atoms were observed. It was found that dehydrogenation reaction proceeded gradually with the increase in the reaction time.

Experimental study of asphaltene onset condition and deposition using electrical deposition technique in the presence of various additives: A novel strategy

Asphaltenes (ASPs) are regarded as high molecular weight components that often deposit in the production lines and downstream infrastructure, leading to pressure drop and reduced production rate. In this paper, we investigated the potential of electro-deposition of ASP an Iranian crude oil sample encountering ASP deposition problems, to reduce the risk of well shut-in. In this regard, a systematic research plan has been designed to use the electro-deposition technique to precipitate and deposit ASP different fluid samples incluiding crude oil/n-heptane, synthetic oil (containing the same ASP)/n-heptane, crude oil/n-heptane/additive and synthetic oil/n-heptane/additive are utilized. The additives such as Linear Alkyl Benzene Sulfonate (LABS) as a surfactant, metal oxide nano-particles such as SiO2, γ-Al2O3, and TiO2 and synthesized mixed-metal oxide nano-particles compounds such as CeNiO3, CeZrO4 and CeCaO3 were used. This work reveals the effect of these additives on the deposition rate of ASP particles from crude oil and compares their effectiveness. Using a homemade apparatus, the optimum direct-current electric field (EF) and time for ASP deposition were found, followed by finding the best solution of crude oil and n-heptane. As for the additives, LABS showed that ASP deposition is critically decreased on the cathode at 2000 ppm for crude oil and 1500 ppm for synthetic oil. Nano-particles exhibit different behavior in an EF. The experimental results indicated that by increasing the concentration of nano-particles, the amount of ASP deposit on the anode decreases. The results indicated that synthesized mixed-metal oxide nano-particles do not change the charge type of ASP and result in ASP deposition reduction utilizing a very low number of nano-particles. Currently, electro-deposition is a key solution to remove ASPs from crude oil. This is due to its high energy efficiency and relatively simple process. Comparing the effects of these newly proposed additives showed that, CeZrO4 nano-particles are more efficient to inhibit ASP deposition.

Evolution mechanisms of bio-oil from conventional and nitrogen-rich biomass during photo-thermal pyrolysis

Photo-thermal (PT) pyrolysis has emerged as a promising technique for efficiently converting biomass into high-quality bio-oil. The pyrolysis characteristics of rice straw (RS) and rapeseed cake (RC) were analyzed using a photo-thermal reactor with heating rates of 20, 200 and 500 °C/min and compared with 20 °C/min fixed-bed (FB) pyrolysis at 750 °C. Due to the uneven temperature distribution caused by its limited heating area, fast PT heating significantly increased the presence of high molecular weight components (>650) in the bio-oil. PT pyrolysis of RS exhibited higher phenolic contents compared to FB pyrolysis, whereas RC oil showed enhanced decomposition of fatty acids through ketonization. In terms of N-compounds, PT slow pyrolysis oil contained more nitriles but fewer linear amines/amides than FB, while more cyclic amides were formed under fast PT pyrolysis. Furthermore, the analysis of heavy components revealed that more aromatic compounds with low H/C ratios were produced in fast PT pyrolysis oil. Overall, PT heating exerted dual effects by reducing secondary reactions and synergistically enhancing inner-particle reactions with fast heating. This study provides valuable insights into the mechanism of bio-oil evolution under PT pyrolysis.

Insights into the formation and stability of soil aggregates in relation to the structural properties of dissolved organic matter from various organic amendments

Organic matter is an important determinant of soil aggregate formation and stability. However, the role of its structure, especially that of dissolved organic matter (DOM) from organic amendments (OAs), in the aggregation process remains imprecise. The purpose of this study was to understand the relationship between the chemical structure of water-extractable organic matter (WEOM), potential source of DOM from OAs, and their aggregate formation/stability functionality through model experiment. The WEOM samples were prepared from bark compost (BC), coffee residue compost (CRC), cattle manure compost (CMC), sewage sludge compost (SSC), fish cake (FC), and rapeseed oil cake (ROC) and characterized using high-performance size exclusion chromatography and 13C nuclear magnetic resonance and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopies. An upland field soil was packed in glass columns and each WEOM solution or ultrapure water (Control) was applied repeatedly during a 30-day period. Aggregate size distribution (>2000, 500–2000, 250–500, 53–250, and <53 µm) was then measured and aggregate stability indices, mean weight diameter (MWD), and geometric mean diameter (GMD) were calculated. The addition of WEOM increased the distributions of soil mass and soil organic carbon (C) into the > 2000 µm aggregate fraction compared to Control treatment, and the ROC-, CRC-, and SSC-WEOM treatments resulted in greater MWD and GMD than Control and/or the other WEOM treatments. The % O-alkyl C (29–59% of total C) and the relative abundance of high-molecular-weight (HMW) fraction (>10 kDa; 2.3–7.1% of total) in WEOM correlated positively with the proportion of > 2000 µm aggregate fraction. The relative abundance of HMW fraction also correlated positively with MWD. These findings suggest that the high amounts of polysaccharides, suggested by % O-alkyl C and supported by DRIFT spectra, and/or other HMW components are desirable structural characteristics of WEOM for promoting macroaggregate formation and aggregate stability.

Purification of a monoclonal antibody using a novel high-capacity multimodal cation exchange nonwoven membrane

A high-capacity, multimodal cation exchange (MMC) chromatographic membrane was developed by conjugating a multimodal ligand – 2-mercaptopyridine-3-carboxylic acid (MPCA) – on a polybutylene terepthalate (PBT) nonwoven fabric. The membrane features an equilibrium binding capacity of ≈ 1000 mg of human polyclonal IgG (IgG) per g of membrane and dynamic binding capacities (DBC10%) ranging from 77.5 to 115.1 mg/mL (residence times of 1 and 5 min, respectively); these values are 2-to-3-fold higher than those of commercial MMC adsorbents. The effects of buffer composition, pH, conductivity on the binding behavior of the MMC-MPCA membrane were investigated in detail. As a moderate cation exchange binder, MPCA enables effective protein elution using buffers with mild pH (8.0–9.0) and conductivity (≈13 mS/cm), thus circumventing the harsh conditions often needed in multimodal chromatography. The MMC-MPCA membrane was evaluated for product capture in bind-and-elute mode on a Chinese hamster ovary (CHO) cell culture harvest containing therapeutic monoclonal antibodies, using commercial multimodal (Capto MMC and MX-Trp-650M) and affinity (AF-rProtein A HC-650F) resins as controls. The MMC-MPCA membrane outperformed the multimodal resins in terms of binding capacity as well as clearance of host cell proteins (HCPs) and aggregates. The membrane was then evaluated by polishing the mAb from a Protein A eluate in bind-and-elute mode. The MMC-MPCA membrane reduced the level of high molecular weight components from 11% to 4% and the HCP content from 1319.7 ppm to 48.7 ppm (LRV of 1.4). Most notably, proteomics analysis of the product demonstrated the clearance of a significant fraction of persistent, high-risk HCPs from the Protein A eluate.

Changes in the structure of polysaccharides under different extraction methods

Changes in the structure of polysaccharides under different extraction methods

High formation of trichloroacetic acid from high molecular weight and ultra-hydrophilic components in freshwater raphidophytes upon chlorination

Raphidophytes are flagellate unicellular algae that causes algal blooms in drinking water sources. In Japan, it was recently reported that the concentration of trichloroacetic acid (TCAA), a major chlorinated disinfection byproduct (DBP), increased dramatically in drinking water when the source water contained raphidophytes. Additionally, raphidophytes produced haloacetic acid (HAA) precursors, especially TCAA precursors, in high concentrations. However, their properties are still unknown, and thus, well-designed countermeasures against DBP formation have not yet been established. Therefore, in this study, the HAA precursors originated from raphidophytes in natural water collected from the algal blooms in Muro Dam (Nara Prefecture, Japan) and Gonyostomum semen (G. semen), a raphidophyte species, cultivated in the laboratory, were characterized to provide the information for establishing suitable treatment strategies. Using several high-performance liquid chromatography columns, solid-phase extraction cartridges, and ultrafiltration devices, and the spectral profiles, we discovered that the HAA precursors are highly hydrophilic and high-molecular-weight compounds with acidic and phenolic functional groups. Further characterization of the high-molecular-weight fraction (> 3 kDa) from the G. semen culture showed that the HAA precursors had a molecular weight of ~10–60 kDa, and that they were not protein molecules despite containing a large amount of nitrogen atoms. Furthermore, the TCAAFP of the fraction (310 ± 25 μg/mg C) were as high as phenol, known as a reactive TCAA model precursor. The presence of unique and unreported DBP precursors was confirmed.