High Molecular Weight Substances Research Articles

Sequestration of Labile Organic Matter by Secondary Fe Minerals from Chemodenitrification: Insight into Mineral Protection Mechanisms.

Labile organic matter (OM) immobilized by secondary iron (Fe) minerals from chemodenitrification may be an effective way to immobilize organic carbon (OC). However, the underlying mechanisms of coupled chemodenitrification and OC sequestration are poorly understood. Here, OM immobilization by secondary Fe minerals from chemodenitrification was investigated at different C/Fe ratios. Kinetics of Fe(II) oxidation and nitrite reduction rates decreased with increasing C/Fe ratios. Despite efficient sequestration, the immobilization efficiency of OM by secondary minerals varied with the C/Fe ratios. Higher C/Fe ratios were conducive to the formation of ferrihydrite and lepidocrocite, with defects and nanopores. Three contributions, including inner-core Fe-O and edge- and corner-shared Fe-Fe interactions, constituted the local coordination environment of mineral-organic composites. Microscopic analysis at the molecular scale uncovered that labile OM was more likely to combine with secondary minerals with poor crystallinity to enhance its stability, and OM distributed within nanopores and defects had a higher oxidation state. After chemodenitrification, high molecular weight substances and substances high in unsaturation or O/C ratios including phenols, polycyclic aromatics, and carboxylic compounds exhibited a stronger affinity to Fe minerals in the treatments with lower C/Fe ratios. Collectively, labile OM immobilization can occur during chemodenitrification. The findings on OM sequestration coupled with chemodenitrification have significant implications for understanding the long-term cycling of Fe, C, and N, providing a potential strategy for OM immobilization in anoxic soils and sediments.

#1800 Cascade filtration in severe pulmonary-kidney syndrome: an one-center experience

Abstract Background and Aims In some forms of rapidly progressive glomerulonephritis (RPGN), the effect of plasma exchange (PE) is not well understood. Cascade filtration (CF) differs from standard PE in that it uses a double filter system, where the first filter is used to separate plasma from whole blood and the second filter is used to filter high-molecular weight substances. In this study, we investigated the efficacy and safety of CF in patients with ANCA-associated vasculitis (AAV) and Goodpasture's syndrome (GPS). Method During one year we included 18 patients with RPGN whose received CF in the study. The eligibility criteria was eGFR ≤15 ml/min/1.73 m2 and/or diffuse alveolar hemorrhage (DAH), presence of antineutrophilic antibodies or anti-GBM-antibodies. CF was performed on a Plasauto Sigma using a Plasmaflo OP-05W plasma separator and a Cascadeflo EC-30W separator with a fresh frozen plasma or 25% albumin solution. All patients received immunosuppressive therapy with steroids and cyclophosphamide, one patient with AAV received rituximab due to anemia and thromobocytopenia. All data were obtained from one hospitalization with the median of 43 days. Results Eight patients with AAV and three patients with GPS met the eligibility criteria. The median age of the patients in the AAV group was 59.8 (48; 66) years, with a female to male ratio of 1:1. All patients had evidence of systemic disease: seven patients had lung damage, including DAH, two patients had arthralgia, one had purpura and one had severe sinonasal involvement. The median creatinine level was 588 µmol/l (382; 1352), dialysis was initiated in 6 patients, and the median Birmingham Vasculitis Activity Score (BVAS) was 17 (15; 20). After three procedures of CF, all patients showed positive changes on CT scan, and dialysis was stopped in three patients. The immunological response to CF was observed quite rapidly in seven patients, with decreasing ANCA titer after three exchanges and decreasing antibody levels after six exchanges in one patient. There was a significant decrease in inflammatory markers, median C-reactive protein at baseline 179 (147; 226) decreased to 23 (2.8; 30.9) mg/l (p = 0.041). The CF was well tolerated with no significant adverse events. One patient receiving rituximab died after 4 months due to a severe COVID 19 infection. Three patients with GPS, one male 23 years old and two females 56 and 60 years old, also received CF. Creatinine concentrations at baseline were 1285, 1299 and 661 µmol/l, BVAS scores were 18, 20 and 15, respectively. After three procedures of CF, there was an immunological response: decrease in antibody levels from 121 U/ml to 15 U/ml, from 88.2 to 18.4 U/ml, from > 200.0 to 85.4 U/ml, CRP from 252 to 0.7 mg/l, from 120 to 5 mg/l, from 81.9 to 12.58 mg/l. There were no deaths and all three patients remained on dialysis. Conclusion CF was an effective and well tolerated method of treating severe AAV and GPS in addition to immunosuppressive treatment. Possibly due to the different filtration principle and the absence of donor plasma, we did not observe any infection-related adverse events and a lower number of procedures of CF was required compared to standard plasma exchanges. Further larger studies are needed to evaluate the benefits and safety of CF in combination with immunosuppressive treatment in RPGN patients.

Review : Field Flow Fractionation

Field flow Fractionation is a technique which is used for the separation of colloidal or high molecular weight substances in liquid solution, flowing through the separation platform, which does not have a stationary phase. It is similar to liquid chromatography, as it works on dilute solutions or suspensions of the solute, carried by a flowing eluent.separation is done by applying a fields like hydraulic, centrifugal, thermal, electrical, magnetic, gravitational or cross flowing, perpendicular to the direction of the sample .Field flow fractionation (FFF) is a chromatography-like separation technique used to separate macromolecules, colloids, and particles. The idea is straightforward. A parabolic velocity profile is created by a laminar flow of carrier liquid between two walls separated by approximately 0.1 mm

Effects of clarithromycin exposure on the growth of Microcystis aeruginosa and the production of algal dissolved organic matter

Antibiotics are commonly found in the aquatic environment, which can affect microbial community compositions and activities, and even have potential adverse impacts on human and ecosystem health. The current understanding of the effects of antibiotics on microalgae growth and algal dissolved organic matter (DOM) remains indistinct. To understand the toxic effects of antibiotics on the microalgae, Microcystis aeruginosa was exposed to clarithromycin (CLA) in this study. Cell density determination, chlorophyll content determination, and organic spectrum analysis were conducted to show the effect of CLA exposure on the growth, photosynthetic activity, and organic metabolic processes of Microcystis aeruginosa. The findings revealed that the physiological status of algae could be significantly influenced by CLA exposure in aquatic environments. Specifically, exposure to 1 μg/L CLA stimulated the growth and photosynthetic activity of algal cells. Conversely, CLA above 10 μg/L led to the inhibition of algal cell growth and photosynthesis. Notably, the inhibitory effects intensified with the increasing concentration of CLA. The molecular weight of DOM produced by Microcystis aeruginosa increased when exposed to CLA. Under the exposure of 60 μg/L CLA, a large number of algal cells ruptured and died, and the intracellular organic matter was released into the algal liquid. This resulted in an increase in high molecular weight substances and soluble microbial-like products in the DOM. Exposure to 1 and 10 μg/L CLA stimulated Microcystis aeruginosa to produce more humic acid-like substances, which may be a defense mechanism against CLA. The results were useful for assessing the effects of antibiotic pollution on the stability of the microalgae population and endogenous DOM characteristics in aquatic ecosystems.

Fluorescence Polarization Assays for Organic Compounds in Food Safety.

Elevated concentrations of toxic organic compounds observed in food products pose serious dangers to human health. Both natural and artificial pollutants can cause food contamination. The stages of food production, packaging, transportation, and storage can also largely cause the appearance of undesirable substances in food products. The health consequences of ingesting food containing toxic contaminants range from mild gastroenteritis to deaths resulting from dysfunctional internal organs and neurological syndromes. The World Health Organization (WHO) sets recommendations for the content of such chemicals in food, including a minimum allowable concentration considered safe for human consumption. However, the control of food products from chemical pollutants is necessary. Moreover, fast, sensitive, and inexpensive methods are needed to detect them at the point of need. Currently, immune analysis methods are most widely used to determine pollutants in food. The development of fluorescence polarization immunoassay (FPIA) methods in a competitive format is a powerful and modern tool for detecting organic molecules in various matrices, thereby making FPIA methods useful for food safety applications. Due to the availability of portable devices for measuring the fluorescence polarization signal, FPIA methods can be used at the point of need. The variety of fluorescent labels and recognizing elements (receptors, monoclonal and polyclonal antibodies, and nanobodies) permits fluorescence polarization (FP) assays to detect significantly lower limits of organic substances. The FP assay is a homogeneous, fast, and quantitative method. The development of various formats of FP assays makes them promising in determining food pollutants. This review summarizes publications on FP analyses for detecting organic contaminants (pesticides, hormones, toxins, antibiotics, and other pharmaceuticals) in food products during 2018-2023. Further, it demonstrates the prospects for using this method to determine pollutants at the point of need and for detecting high molecular weight substances, fungi, and bacterial infections during food safety inspections.

#6760 EFFICACY OF HEMOSORPTION IN REMOVAL OF HIGH MOLECULAR WEIGHT UREMIC TOXINS IN CHRONIC HEMODIALYSIS PATIENTS

Abstract Background and Aims Symptoms associated with the accumulation of large uremic toxins (the development of chronic inflammation, accelerated progression of cardiovascular diseases and an increase in the incidence of protein-energy malnutrition) are common for patients who get chronic hemodialysis (HD) for a long time. HD effectively removes small and medium molecules (up to 15 kDa), while convection techniques, which are not always available, are used to remove substances of higher molecular weight. An alternative strategy for removing uremic toxins, especially large medium molecules, is the use of sorption techniques. The aim of the study was to compare the removal efficiency of substances with a molecular weight from 11.8 to 45 kDa using HD on a high-flux membrane and a combination of a high-flux membrane with hemosorption. Method The study included patients with a duration of hemodialysis therapy for more than 5 years. Blood sampling was carried out before and after the procedures, in the average RRT session per week. The following indicators were determined: β-2-microglobulin, leptin, free light chains (FLC) κ and λ, Il-6. The first HD session was performed on a Fresenius Fx-80 high-flux membrane. The second procedure (one week after) was carried out using the same filter, but with the connection of a Jafron HA130 sorption column (HD+HP). The duration of the both procedures was 4 hours. Blood flow did not exceed 300 ml/min. Results Total 10 patients were included in the study. Mean duration of renal replacement therapy was 12±5 years. The ratio of men and women was equal. Mean age 54±12 years. All patients used AV fistulas as vascular access. When determining and comparing the concentrations of β-2-microglobulin, leptin, Il-6, a comparable significant decrease in concentrations was noted after both procedures without significant statistical differences between the methods. At the same time, the efficiency of FLC removal on HD and HD+GP was convincingly different: - average kappa-FLC concentration change after HD was +1.8±9.1 mcg/ml, after HD+GP: -9.4±7.5 mcg/ml, p = 0.04. - average lambda -FLC concentration change after HD/HD+GP was +3.2±16.3 and -12.9±4.4 mcg/ml, respectively. p = 0.02. Conclusion The use of sorption techniques as an adjunct to standard HD therapy can increase the excretion of medium-large molecular substances, such as FLC kappa/lambda, which may help reduce the severity of symptoms associated with the accumulation of these uremic toxins. Additional studies are required to evaluate the clinical effectiveness of the new sorption method in chronic HD.

#5130 THE EXPERIENCE OF SELECTIVE PLASMA EXCHANGE THERAPY IN PATIENTS WITH MULTIPLE MYELOMA

Abstract Background and Aims High concentrations of free light chains (FLCs) in multiple myeloma lead to cast-nephropathy and obstructive acute renal failure in 18-56% of patients. The aim of this research is to estimate the efficiency of extracorporeal free light chains of immunoglobulin elimination under this pathological condition during plasma exchange therapy using selective filters. Method Selective plasma exchange therapy (SEPET) was carried out in 11 patients with multiple myeloma. The patients were 61 [47-69] years old. Paraproteinemia level at primary examination varied from 1.6 to 78.8 g/liter. All patients exhibited proteinuria of 0.56 to 12.7 g/day, Bence Jones protein excretion (from 0.4 to 11.2 g/day) was detected in 9 cases. Blood creatinine levels ranged from 272 μmol/L to 534 μmol/L. None of the patients required renal replacement therapy. FLCs levels above 500 mg/L, irrespective of azotemia level, served as an indication for starting the procedure. All patients received VMP induction chemotherapy after sessions of selective plasma exchange therapy. SEPET was carried out on a “Multifiltrate” (Fresenius) hemodialysis machine in hemofiltration mode. «Evaclio 2C20» plasmafilter (Japan) was used. Patients underwent one procedures of SEPET in a dose of 3 volumes of circulating plasma. Blood flow velocity during varied from 40 to 60 ml/min, the duration of each procedure was 5-6 hours. Plasma substitution was performed with «Prismasol K4» solution - 10.0 L and albumin solution 20%-400 ml. Regulated clotting by nonfractionated heparin was calculated individually from the APTT values. No early or delayed complications of extracorporeal hemocorrection were recorded. FLCs, creatinine levels, and coagulogram results of patients were examined before and after the procedure. Results Analysis of serum FLC values before treatment showed a significant increase of κ- or λ-FLC levels, significantly surpassing normal values: 3-21.5 mg/liter κ-FLC and 5-27 mg/liter λ-FLC, with κ/λ-FLC proportion of 0.25-1.65. The primary levels of involved FLC medians in the group were 472 [312;44700] mg/L for κ-FLC and 163 [ 473; 24673] mg/L for λ-FLC, κ/λ-FLC proportions were 2.89. Through the membrane of the plasma filter “Evaclio 2C20” are sieved and removed substances with a molecular weight less than the molecular weight of albumin (65 kD). Kappa FLCs circulate as monomers of 22 kDa but may assemble into dimers of 45 kDa, particularly lambda FLCs. There is a partial loss of albumin. High molecular weight substances do not pass through this membrane. During SEPET the κ-FLC level in the plasmafiltrate was 272 mg/L, the λ-FLC level was 94 mg/L. After SEPET median serum κ-FLC was 231 mg/L, median serum λ-FLC was 96 mg/L. Compared with baseline data, serum FLC levels decreased after 24 hours, so that median serum κ-FLC was 281 mg/L, median serum λ-FLC was 101 mg/L. Clinical tolerance of extracorporeal detoxification was satisfactory and hemodynamically stable in all patients; and there were no were traumas of blood elements or decrease of serum albumin. Renal function recovered in 3 patients in the course of therapy, improved in 5 patients with renal insufficiency, and remained unchanged in 3 patients. Conclusion The Selective plasma exchange therapy directly removes FLCs excess from circulating blood. Rapid reduction of FLCs level in the course of selective extracorporeal elimination can prevent the development of irreversible renal failure and make it possible to carry out adequate antitumor therapy.

Environmentally Friendly Method for Enhanced Heavy Oil Recovery by In-Situ Upgrading Process Based on Catalytic Steam Injection

Any crude oil with an API gravity below 20 is considered heavy crude, and crude oil with an API gravity below 10 is considered extremely heavy. Conventional oil is lighter and less dense than unconventional oil resources such as heavy oil, extra-heavy oil, and bitumen. When the world’s conventional crude oil stocks are depleted, heavy oil resources will be well-positioned to continue satisfying demand for petroleum products. The economic viability of heavy oil depends on its quality being increased. The use of a catalytic steam injection in-situ upgrading technique to improve heavy oil recovery is discussed here. Previous research has shown that in-situ upgrading has a high catalytic ability to upgrade heavy crude oil by decreasing viscosity, increasing the amount of saturates (obviously low carbon number alkanes), and causing the thermal decomposition of high molecular weight substances such as asphaltenes and resin. There may be advantages to in-situ upgrading over more traditional methods of surface upgrading.

Dissolving microneedles for effective and painless intradermal drug delivery in various skin conditions: A systematic review.

Intra- and transdermal administration of substances via percutaneous injection is effective but considered painful, and inconvenient in addition to bringing forth biohazardous waste material. In contrast to injection, topical drug application, which includes ointments, creams and lotions, increases the local drug load. Moreover, it has reduced side effects compared to systemic administration. However, the epidermis poses a barrier to high molecular weight substances, limiting the delivery efficiency. Dissolving microneedles (DMN) are hydrophilic, mostly polymer-based constructs that are capable of skin penetration and were developed to provide painless and direct dermal drug delivery. This systematic review provides a comprehensive overview of the available clinical evidence for the use of DMN to treat various skin conditions. According to the PRISMA statement, a systematic search for articles on the use of DMN for dermatological indications was conducted on three different databases (Pubmed, Embase, and the Cochrane library). Only human clinical trials were considered. Qualitative assessment was done by two separate reviewers using the Cochrane risk of bias (RoB 2) and Chambers' criteria assessment tools. The search yielded 1090 articles. After deduplication and removal of ineligible records, 889 records were screened on title and abstract. Full text screening was done for 18 articles and ultimately 17 articles were included of which 15 were randomized controlled trials and two were case series. The quality assessment showed that the majority of included studies had low to no risk of bias. Clinical data supports that DMN are an excellent, effective, and pain free drug delivery method for multiple dermatological disorders including skin aging, hyperpigmentation, psoriasis, warts, and keloids by supplying a painless and effective vehicle for intradermal/intralesional drug administration. Microneedle technology provides a promising non- to minimally-invasive alternative to percutaneous injection.

Mitigation of ultrafiltration membrane fouling by a simulated sunlight-peroxymonosulfate system with the assistance of irradiated NOM

Oxidation pretreatments prior to ultrafiltration are hindered by the need for energy input and sludge disposal. Herein, a simulated sunlight-induced natural organic matter (NOM) for peroxymonosulfate (PMS) activation was used as pretreatment to alleviate ultrafiltration membrane fouling caused by NOM itself in the Songhua River water. When light intensity was over 100 mW/cm2, the pretreatment removed NOM effectively, characterized with UV254, dissolved organic carbon (DOC) and maximum fluorescent intensity (Fmax), and improved filtration flux. At 200 mW/cm2 light intensity and 0.5 mM PMS, 57.5% of UV254 and 18.5% of DOC were removed, and humic-like fluorescent component was degraded by 84%-94% while ∼60% for protein-like substance. Membrane flux was increased by 94%, and reversible and irreversible fouling resistances were reduced by 62.4% and 51.9%, respectively. Both total fouling index (TFI) and hydraulic irreversible fouling index (HIFI) were moderately correlated with the DOC, whereas they prominently correlated with the UV254 and the Fmaxs of all fluorescence components, which could be served as key indicators to predict and control membrane fouling. Mathematical modeling showed that the pretreatment alleviated the fouling in the membrane pores and cake layer. The simulated sunlight-induced NOM (3NOM* and eaq¯) could activate PMS to form active species, which enabled to oxidize high molecular weight (MW) substances and mineralize low MW compounds in NOM as well as hinder their linking with inorganic cations, thereby reducing organic and inorganic membrane fouling simultaneously. This study may provide a new strategy for decentralized potable water treatment, especially in a single household or community.

Indirect effect of alpha-1-antitrypsin on endotoxin-induced IL-1β secretion from human PBMCs.

Human alpha-1-antitrypsin (AAT) encoded by the SERPINA1 gene, is an acute phase glycoprotein that regulates inflammatory responses via both protease inhibitory and non-inhibitory activities. We previously reported that AAT controls ATP-induced IL-1β release from human mononuclear cells by stimulating the release of small bioactive molecules. In the current study, we aimed to elucidate the identity of these putative effectors released from human PBMCs in response to AAT, which may inhibit the LPS-induced release of IL-1β. We pre-incubated human PBMCs alone or with different preparations of AAT (4 mg/ml) for 30 min at 37°C, 5% CO2, and collected cell supernatants filtered through centrifugal filters (cutoff 3 kDa) to eliminate AAT and other high molecular weight substances. Supernatants passed through the filters were used to culture PBMCs isolated from the autologous or a heterologous donors with or without adding LPS (1 μg/ml) for 6 h. Unexpectedly, supernatants from PBMCs pre-incubated with AAT (Zemaira®), but not with other AAT preparations tested or with oxidized AAT (Zemaira®), lowered the LPS-induced release of IL-1β by about 25%–60% without affecting IL1B mRNA. The reversed-phase liquid chromatography coupled with mass spectrometry did not confirm the hypothesis that small pro-resolving lipid mediators released from PBMCs after exposure to AAT (Zemaira®) are responsible for lowering the LPS-induced IL-1β release. Distinctively from other AAT preparations, AAT (Zemaira®) and supernatants from PBMCs pre-treated with this protein contained high levels of total thiols. In line, mass spectrometry analysis revealed that AAT (Zemaira®) protein contains freer Cys232 than AAT (Prolastin®). Our data show that a free Cys232 in AAT is required for controlling LPS-induced IL-1β release from human PBMCs. Further studies characterizing AAT preparations used to treat patients with inherited AAT deficiency remains of clinical importance.

Application of mathematical analysis on dialysis.

Hemodialysis is a blood purification method based on solute removal by diffusion and incorporates filtration to improve the efficiency of water removal and removal of high molecular weight substances. It is now a well-established treatment, due to the improved performance of dialyzers. This review outlines the development process of dialyzers, focusing on the application based on the mathematical analysis. First, phenomena occurring in the vicinity of the dialysis membrane are explained using a film model for diffusion and a gel polarization model for filtration. Then, currently established dialyzer designs are introduced using mathematical analysis. Furthermore, the design of dialyzers to promote internal filtration, the designs of hemodiafilters suitable for online hemodiafiltration (HDF), and the design of compact dialyzer for are also presented.

Accelerated stabilization of high solid sludge by thermal hydrolysis pretreatment in autothermal thermophilic aerobic digestion (ATAD) process.

Autothermal thermophilic aerobic digestion (ATAD) is a rapid biological treatment technology for sludge stabilization. To improve digestion efficiency and shorten stabilization time, thermal hydrolysis pretreatment was employed before ATAD of high solid sludge. The results showed that accelerated stabilization of high solid sludge (total solid=10.1%) was achieved by thermal hydrolysis pretreatment with volatile solid removal efficiency of 40.3% after 8 days of ATAD, 11 days earlier than unpretreated sludge. The enhanced release and hydrolysis of intracellular organics resulted in a solubilization degree of 45.3%. The reduced sludge viscosity and improved fluidity after thermal hydrolysis facilitated mixing, aeration and organics degradation during ATAD. Excitation emission matrix analysis indicated that the fluorescence intensity of soluble microbial byproduct and tyrosine-like protein increased markedly after thermal hydrolysis and decreased after ATAD. The proportion of high molecular weight (MW>10kDa) substances in the supernatant increased significantly after thermal hydrolysis, while the low MW (MW<1kDa) substances decreased after ATAD. The significant difference in microbial composition between the pretreatment and control groups elucidated the accelerated sludge stabilization under thermal hydrolysis. This work provides an efficient and practical strategy to achieve rapid stabilization of high solid sludge.

Characterization of DOM Released from Bacteria in Response to Chlorine in Water Based on Indicator Bacteria E. coli

In this study, Escherichia coli (E. coli) was used as an indicator bacterium treated with five different concentrations of chlorine (0.1; 0.5; 1.0; 2.0, and 5.0 mg/L) and without chlorine (0.0 mg/L) to evaluate the changes in the DOM characteristics. The dissolved organic carbon (DOC) concentration initially increased along with the chlorine concentrations and decreased after 24 hours (0.0 and 0.1 mg/L) and 168 hours (0.5; 1.0; 2.0 and 5.0 mg/L). Ultra-violet absorbance at 260 nm (UV260) showed that the absorbance decreased for control without chlorine (0.0 mg/L) and 0.1 mg/L chlorine, while increased for other concentrations of chlorine within 120 hours. The DOC and UV260 results indicated that the high concentrations of chlorine initiated high contents of DOM which contained more humic-like molecules than the DOM released from E. coli without chlorine. Fluorescence excitation-emission matrix (EEM) analysis suggested that the DOM released from E. coli without chlorine enriched with protein-like substances, whereas the fulvic-like and humic-like substances more intensified in the DOM for the high concentrations of chlorine (>1.0 mg/L). The molecular weight distribution of DOM showed that the intensity of high molecular weight substances and polydispersity increased along with chlorine concentration and contact time, whereas the low molecular weight substances were relatively higher in the DOM for control without chlorine. The obtained results of this study would be useful for a better understanding of the variation of DOM during treatment and could be used as an important reference for optimizing the operation condition of the water treatment plants.

Effect of chemical component characteristics of waste cooking oil on physicochemical properties of aging asphalt

The combined utilization of waste cooking oil (WCO) and reclaimed asphalt pavement (RAP) is attractive for economic, environmental, and energy benefits. However, the quality stability of WCO is poor due to its wide sources, which limits the further development of WCO recycled RAP. In this study, the classification method of WCO was proposed according to the molecular weight difference of its chemical components, and WCO was classified into three categories including light components (LC), intermediate components (IC), and heavy components (HC). Meanwhile, the characteristics of these three WCO components and their effects on the physicochemical properties of aging asphalt were investigated comprehensively. The experimental results show that the softening ability of different components of WCO on aging asphalt is mainly determined by their molecular weight and thermal stability. Furthermore, LC rich in methyl palmitate is easy solidification and volume expansion at the low temperature, which is not conducive to the repair of low-temperature ductility of aged asphalt. The chemical property analyses of recycled asphalt indicate that there is no chemical reaction between the components of WCO and the aging asphalt. The physical dilution ability of WCO components on carbonyl index, sulfoxide index, and high molecular weight substances of aging asphalt is positively correlated with their molecular weight. In addition, HC contains chemical substances similar in composition to asphalt, which has the most obvious effect on the colloidal structure of aging asphalt. Overall, the classification method for WCO and related findings found in this study provides a reference for ensuring the quality stability of WCO and its industrial application in the recycling of aged asphalt.

Molecular transformation of dissolved organic matter and the formation of disinfection byproducts in full-scale surface water treatment processes

Dissolved organic matters (DOM) have important effects on the performance of surface water treatment processes and may convert into disinfection by-products (DBPs) during disinfection. In this work, the transformation of DOM and the chlorinated DBPs (Cl-DBPs) formation in two different full-scale surface water treatment processes (process 1: prechlorination-coagulation-precipitation-filtration; process 2: coagulation-precipitation-post-disinfection-filtration) were comparatively investigated at molecular scale. The results showed that coagulation preferentially removed unsaturated (H/C < 1.0 and DBE > 17) and oxidized (O/C > 0.5) compounds containing more carboxyl groups. Therefore, prechlorination produced more Cl-DBPs with H/C < 1.0 and O/C > 0.5 than post-disinfection. However, the algal in the influent produced many reduced molecules (O/C < 0.5) without prechlorination, and these compounds were more reactive with disinfectants. Sand filtration was ineffective in DOM removal, while microorganisms in the filter produced high molecular weight (MW) substances that were involved in the Cl-DBPs formation, causing the generation of higher MW Cl-DBPs under post-disinfection. Furthermore, the CHO molecules with high O atom number and the CHON molecules containing one N atom were the main Cl-DBPs precursors in both surface water treatment processes. In consideration of the putative Cl-DBPs precursors and their reaction pathways, the precursors with higher unsaturation degree and aromaticity were prone to produce Cl-DBPs through addition reactions, while that with higher saturation degree tended to form Cl-DBPs through substitution reactions. These findings are useful to optimize the treatment processes to ensure the safety of water quality.

EFFECTS OF MOLECULAR WEIGHT ON MICROFLUIDIC SEPARATION

the molecular weight effects the diffusion of molecules in the interface of laminar flow form in a microfluidic channel. Two mixtures of PS with anisole and PEG were used to evaluate the molecular weight effect on the microfluidic separation. Also, the separation of a low molecular weight substance of anisole from the mixture with a high molecular weight substance of PS is proved experimentally. However, the separation of PEG from the mixture with PS remained difficulty. More information about diffusion in microfluidic channel and can be applied to polymer science and separation fields.

Improvement of the computational method for determining the cryoscopic temperature of functional ice cream mixtures

Nowadays the functional ice cream production keeps developing. Due to that the traditional composition of the ice cream is amended. In case of substitution of the low molecular weight nutrients (sucrose, lactose and mineral salts of dry skimmed milk residue) with technologically functional nutrients, it changes the cryoscopic temperature, which influences the parameters of production process, in particular the temperature of the ice cream getting from the freezer. In this regard, the problem of calculating the cryoscopic temperature of ice cream mixtures has become acute, since it is not possible to find this parameter experimentally at all food enterprises. While calculating the cryoscopic temperatures on the basis of existing reference data, in some cases the authors encountered a significant (more than 0.5 °C) deviation of the calculation results from the experimental data. In order to establish the cause of these deviations, the authors analyzed aqueous solutions of sucrose, fructose, trehalose, erythritol, maltodextrin, polydextrose, sorbitol, glucose-fructose syrup, dry glucose syrup, inulin in concentrations that provide for the cryoscopic temperatures of solutions within the range from 0 °C to minus 6 °C. The cryoscopic temperature of the solutions was measured by an osmometer-cryoscope, and the conventional molecular weight of the substances was calculated on the basis of Raoult ratio, taking into account the high molecular weight substances and admixed impurities. It was shown that the values of the conventional molecular weight for trehalose and sorbitol solutions differ by more than 15% from the values of chemically pure substances due to presence of low molecular weight monomers in their composition. The presented experimental data on the conventional molecular weight values can be used for calculation of cryoscopic temperature of various types of mixtures used for ice cream production. As an example of application of obtained clarified values of conventional molecular weights, this article provides a method for calculation of cryoscopic temperature of low sucrose and sucrose-free ice cream mixtures, as well as a comparison of the calculation results with experimentally obtained data.

The Poly(chloro-p-xylylene)-Ag Metal-Polymer Nanocomposites Obtained by Controlled Vapor-Phase Synthesis for SERS Effect Realisation

Substrates based on the metal-polymer nanocomposites 2,3-dichloro-p-xylylene-silver (PCPX-Ag) that realize the effect of surface-enhanced Raman scattering (SERS) were developed. To obtain nanocomposites, the vapor-phase polymerization method was used (VDP), which makes it possible to control the nanocomposite microstructure. In the process of self-assembly during VDP, nanocomposite films with inclusions of silver particles were formed on the polycore substrates. Silver content varied from 2.5 to 16% vol. The possibility of using such substrates for the detection of low-molecular substances, for example 5,5′-dithiobis- (2-nitrobenzoic acid) (DTNB) analyte, by the SERS method with an enhancement factor of up to 104, was demonstrated. The dependence of the SERS spectra enhancement on the microstructure of the nanocomposite and the silver content was determined. The optical and morphological properties of nanocomposites were also investigated and their dependence on the silver content was shown. It has been demonstrated that the nanocomposite is SERS selective since when working with complex solutions in the presence of high molecular weight substances, signal enhancement was only observed for low molecular weight substances.

Forces involved in freeze-induced egg yolk gelation: Effects of various bond dissociation reagents on gel properties and protein structure changes

Urea, sodium dodecyl sulfate (SDS) and β-mercaptoethanol (2-ME) were used to monitor the roles of hydrogen bonds, hydrophobic interactions and disulfide bonds in frozen egg yolk. Yolk samples were prepared with a denaturant, and the textural characteristics, turbidity properties, protein patterns and structures were analysed. The results showed that SDS or 2-ME addition to egg yolk promoted its turbidity and texture properties, but urea changed the turbidity differently. SDS-PAGE results showed that yolk protein patterns with urea slightly reduced the amount of high molecular weight substances, whereas SDS and 2-ME addition increased the amount. ATR-FTIR spectroscopy revealed that the protein secondary structures changed from ordered structures to random coils. The texture properties were correlated with the protein secondary structure, especially β-sheets and β-turns. Thus, the three bond dissociation reagents induced protein denaturation. Hydrogen bonds were the critical force affecting frozen egg yolk gelation, followed by hydrophobic interactions and disulfide bonds.