High Molecular Substances Research Articles

Supramolecular structure and thermal transformations of modified resinous-asphaltene substances

A detailed study of the supramolecular structure of high molecular weight resinous-asphaltene substances (RAS) and the study of their stability to thermal-oxidative degradation processes in the presence of surfactants is a promising scientific direction and can become the basis for the development of additional oil treatment processes and, as a result, the intensification of thermal transformations of oil dispersed systems (ODS). In the work it has been established that the maximum modifying effect, which consists in reducing the amount of asphaltenes by 8–11 % and increasing the concentration of resins, saturated and aromatic hydrocarbons in the composition of the dispersion medium, is achieved by the interaction of ODS with octadecylpropylenediamine, alkyldiamine with the content of ethoxylated groups n = 3–6 and butyl coconut fatty alcohol ester with n = 10. This fact is due to a change in the geometric parameters of asphaltene nanoaggregates due to the adsorption of these surfactants on their surface. Thus, against the background of an increase in the interplanar distances of condensed aromatic layers dm from 3.66 to 3.85 Å and values of the intrachain distance from 5.71 to 5.80 Å, the average diameter of aromatic layers decreases by 0.67–2.36 Å and the average height of their pack by 1.52–2.64 Å, while the average number of layers in a pack is 5. Estimation of the results of thermal analysis indicates that the RAS thermograms have a similar form with three endoeffects with minima in the ranges of ~ 34.7–37.7 °C (I); 325.7–339.3 (II) and 434.8–438.7 °С (III) and one exoeffect with a maximum of ~ 460.5–475.3 °С (IV). With a decrease in the factor of crystallinity and aromaticity of RAS, their resistance to the processes of thermo-oxidative degradation in the temperature region of coke formation increases. The energy of thermal-oxidative destruction for modified systems by surfactants exceeds by 21.6 kJ/mol of this indicator for unmodified RAS and is 62.07 ÷ 66.13 kJ/mol.

What Is the Molecular Weight of "High" Molecular Weight Dissolved Organic Matter?

The use of ultrafiltration to isolate high molecular weight dissolved organic matter (HMWDOM) from seawater is a fundamental tool in the environmental organic chemist's toolbox. Yet, important characteristics of HMWDOM relevant to its origin and cycling, such as its molecular weight distribution, remain poorly defined. We used diffusion-ordered NMR spectroscopy coupled with mixed-mode chromatography to separate and characterize two major components of marine HMWDOM: acylpolysaccharides (APS) and high molecular weight humic substances (HS). The molecular weights (MWs) of APS and HS both fell within distinct, narrow envelopes; 2.0-16 kDa for APS and 0.9-6.5 kDa for HS. In water samples from the North Pacific Ocean the average MW of both components decreased with depth through the mesopelagic. However, the minimum MW of APS was >2 kDa, well above the molecular weight cutoff of the ultrafilter, suggesting APS removal processes below 2 kDa are highly efficient. The MW distribution of APS shows only small variations with depth, while the MW distribution of HS narrowed due to removal of HMW components. Despite the narrowing of the MW distribution, the concentration of HS did not decrease with depth between 15 and 915 m. This suggests that HMW HS produced in surface waters was either degraded into lower MW compounds without significant remineralization, or that HMW HS was remineralized but replaced by an additional source of HS in the mesopelagic ocean. Based on these results, we propose potential pathways for the production and removal of these major components of HMWDOM.

Sediment porewaters serve as a transient organic carbon pool at the land-ocean interface

The organic carbon (OC) cycle at the land-ocean interface is an important component of the global carbon budget, yet the processes that control the transfer, transformation, and burial of OC in these regions remain poorly understood. In this work, we examined sedimentary OC (SOC) in short core sediments, dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and chromophoric dissolved organic matter (CDOM), as well as other solutes in sediment porewaters of the Changjiang Estuary and adjacent East China Sea (ECS) shelf. The main goal of this work is to investigate the variation of the sources and composition of different forms of carbon in estuarine sediments associated with different sedimentary regimes, to further understand the role of sediment porewater in carbon sequestration at the land-ocean interface. Concentrations of Fe2+ and Mn2+ in porewaters of the muddy sediments are much higher than those in the sandy sediments, and SO42− decreases with depth in the deep sediment layer, indicating the degradation of SOC in mobile muds is mainly driven by suboxic and/or anoxic diagenetic processes (e.g., iron-manganese reduction). The accumulation of DIC in the muddy sediment is higher compared to the sandy sediment, indicating relatively complete SOC remineralization. The DOC in porewaters of the muddy areas is mainly composed of highly degraded and low molecular weight humic-like substances (C1), whereas in the sandy area, porewater DOC is mainly composed of less degraded and high molecular weight protein-like substances (C2 and C3). The average DOC stock (28.5 t/km2) in the upper 30 cm sediment porewaters is significantly higher than that of DIC (12.5 t/km2) in sandy area, but less in muddy areas (17.0 t/km2 of DOC vs. 25.4 t/km2 of DIC). The total DOC stock in sediment porewaters of the sandy area accounted for ∼61 % of DOC stock in water column of the ECS, indicating that the porewater is an important DOC pool in the ECS. However, this DOC pool is rather transient due to its high reactivity and mobility, especially in sandy area. Nevertheless, compared with other marine environments, the carbon stock of DOC (average of 43.8 t/km2) in porewaters of stable sedimentary environments is much higher than that of DIC (average of 21.7 t/km2). This work further supports the notion that sedimentary regime plays an important role in OC cycling at the land-ocean interface and highlights the significance of sediment porewaters as a vast carbon pool in marine ecosystems.

Distribution, chemical, and molecular composition of high and low molecular weight humic-like substances in ambient aerosols

Abstract. Humic-like substances (HULIS) encompass a continuum of molecular weight (MW) ranges, yet our understanding of how HULIS characteristics vary with MW is still limited and not well established. In this study, a combination of ultrafiltration and solid-phase extraction protocols was employed to fractionate the high MW (HMW; > 1 kDa) and low MW (LMW; < 1 kDa) HULIS fractions from ambient aerosols collected during summer and winter at a rural site. Subsequently, comprehensive characterization using total organic carbon, high-performance size exclusion chromatography (HPSEC), UV-visible (UV-vis) and fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR), and negative electrospray ionization high-resolution mass spectrometry (ESI–HRMS) were conducted. The results revealed that HMW HULIS were dominated by larger-sized chromophores, substantially constituting a higher fraction of total organic carbon and UV absorption at 254 nm than LMW HULIS. While both HMW and LMW HULIS shared similar fluorophore types and functional groups, the former exhibited higher levels of humification and a greater presence of polar functional groups (e.g., −COOH; > C=O). HRMS analysis further unveiled that molecular formulas within HMW HULIS generally featured smaller sizes but higher degrees of unsaturation and aromaticity compared to those within LMW HULIS fractions. This observation suggests the possibility of small molecules assembling to form the HMW HULIS through intermolecular weak forces. Moreover, HMW HULIS contained a higher proportion of CHON but fewer CHO compounds than LMW HULIS. In both HMW and LMW HULIS, the unique molecular formulas were primarily characterized by lignin-like species, yet the former displayed a prevalence of N-enriched and highly aromatic species. Additionally, HMW HULIS contained more unique lipid-like compounds, while LMW HULIS exhibited a distinct presence of tannin-like compounds. These findings provide valuable insights into the distribution, optical properties, and molecular-level characteristics of HULIS in atmospheric aerosols, thereby advancing our understanding of their sources, composition, and environmental implications.

Production, purification, and functional characterization of glucan exopolysaccharide produced by Enterococcus hirae strain OL616073 of fermented food origin

Microbial exopolysaccharides (EPS) are high molecular weight polymeric substances with great diversity and variety of applications in the food and pharma industry. In this study, we report the extraction of an EPS from Enterococcus hirae OL616073 strain originally isolated from Indian fermented food and its purification by ion exchange and size exclusion chromatography for physical-functional analyses. The EPS showed two prominent fractions (EPS F1 and EPS F2) with molecular mass 7.7 × 104 and 6.5 × 104 Da respectively by gel permeation chromatography. These fractions were further characterized by FTIR, HPTLC, GC–MS, and NMR as a homopolysaccharide of glucose linked with α-(1 → 6) and α-(1 → 3) glycosidic linkages. The porous, spongy, granular morphology of EPS was observed under scanning electron microscopy. EPS has revealed strong physico-functional properties like water solubility index (76.75 %), water contact angle (65.74°), water activity (0.35), hygroscopicity (3.05 %), water holding capacity (296.19 %), oil holding capacity (379.91 %), foaming capacity (19.58 %), and emulsifying activity (EA1–72.22 %). Rheological analysis showed that aqueous solution of EPS exhibited a non-Newtonian fluid behavior and shear-thinning characteristics. Overall, EPS exhibits techno functional properties with potential applications as a functional biopolymer in food and pharma industry.

Structural forming of soil composites using as a pavement subgrade strengthening

The article substantiates the possibility of obtaining composite materials with improved functional properties to strengthen the subgrade, containing technogenic soil stabilized by an additive based on a gelling polymer. The introduction of technogenic soils into composites will not only reduce the consumption of expensive materials, but also solve a complex of acute environmental problems. Composite materials can be used in the construction of structural layers of road pavements, foundations of buildings and structures, sites for various purposes, for the prevention and elimination of defects in the foundations of engineering structures during their construction, reconstruction and repair, including in permafrost areas. Stabilized technogenic soils are more durable, frost-resistant and waterproof, which makes them applicable for creating impervious curtains in hydraulic structures and sealing storage facilities for hazardous substances. The cryogenic effect on a composite material allows one to vary its properties within a wide range and modify its macroporous structure. Studying the process of structure formation of the resulting organic-inorganic materials, consisting of macromolecules of high-molecular substances and inorganic inclusions that have undergone cryogenic treatment, will make it possible to specifically regulate their performance characteristics. The best values of strength characteristics were obtained for samples with a stabilizing additive concentration of 100 g/l. The resulting composite materials are hydrophobic, frost-resistant, characterized by a compressive strength of 2.3–6.5 MPa and a thermal conductivity of 0.19–0.20 W/(m·K). Data from differential scanning calorimetry and thermogravimetry and IR spectroscopy revealed that the binding of mineral particles by a stabilizing additive occurs due to the formation of organomineral complexes with the participation of clay minerals and the restructuring of hydration shells. SEM data indicate that crystallinity zones formed due to hydrogen bonds of hydroxyl groups of neighboring polymer chains can participate in the formation of the composite structure. An increase in the number of cryogenic treatment cycles promotes additional structuring and strengthening of the polymer phase due to the formation of additional nodes of the supramolecular network, ordering of crystallinity zones and the appearance of compacted areas in the structure. Computed X-ray tomography revealed an increase in the density of the composite upon drying, which helps to increase its strength characteristics. The structure of the sample is characterized by heterogeneity of the pore space, which is characterized by the presence of both fine-porous and large-porous regions, which determines its thermophysical properties.

Mass Spectrometry-Based Evaluation of the Bland-Altman Approach: Review, Discussion, and Proposal.

Reliable quantification in biological systems of endogenous low- and high-molecular substances, drugs and their metabolites, is of particular importance in diagnosis and therapy, and in basic and clinical research. The analytical characteristics of analytical approaches have many differences, including in core features such as accuracy, precision, specificity, and limits of detection (LOD) and quantitation (LOQ). Several different mathematic approaches were developed and used for the comparison of two analytical methods applied to the same chemical compound in the same biological sample. Generally, comparisons of results obtained by two analytical methods yields different quantitative results. Yet, which mathematical approach gives the most reliable results? Which mathematical approach is best suited to demonstrate agreement between the methods, or the superiority of an analytical method A over analytical method B? The simplest and most frequently used method of comparison is the linear regression analysis of data observed by method A (y) and the data observed by method B (x): y = α + βx. In 1986, Bland and Altman indicated that linear regression analysis, notably the use of the correlation coefficient, is inappropriate for method-comparison. Instead, Bland and Altman have suggested an alternative approach, which is generally known as the Bland-Altman approach. Originally, this method of comparison was applied in medicine, for instance, to measure blood pressure by two devices. The Bland-Altman approach was rapidly adapted in analytical chemistry and in clinical chemistry. To date, the approach suggested by Bland-Altman approach is one of the most widely used mathematical approaches for method-comparison. With about 37,000 citations, the original paper published in the journal The Lancet in 1986 is among the most frequently cited scientific papers in this area to date. Nevertheless, the Bland-Altman approach has not been really set on a quantitative basis. No criteria have been proposed thus far, in which the Bland-Altman approach can form the basis on which analytical agreement or the better analytical method can be demonstrated. In this article, the Bland-Altman approach is re-valuated from a quantitative bioanalytical perspective, and an attempt is made to propose acceptance criteria. For this purpose, different analytical methods were compared with Gold Standard analytical methods based on mass spectrometry (MS) and tandem mass spectrometry (MS/MS), i.e., GC-MS, GC-MS/MS, LC-MS and LC-MS/MS. Other chromatographic and non-chromatographic methods were also considered. The results for several different endogenous substances, including nitrate, anandamide, homoarginine, creatinine and malondialdehyde in human plasma, serum and urine are discussed. In addition to the Bland-Altman approach, linear regression analysis and the Oldham-Eksborg method-comparison approaches were used and compared. Special emphasis was given to the relation of difference and mean in the Bland-Altman approach. Currently available guidelines for method validation were also considered. Acceptance criteria for method agreement were proposed, including the slope and correlation coefficient in linear regression, and the coefficient of variation for the percentage difference in the Bland-Altman and Oldham-Eksborg approaches.

The Investigation of the effect of laser radiation on the dielectric properties of polymethylmethacrylate

The problem of studying the interaction of laser radiation with polymer materials lies in the study of the effect of intense energy fluxes on matter. The effect of pulsed laser radiation on a high-molecular substance was studied from changes in the electrical parameters of the irradiated materials. Changes in ε’, tg δ depending on the frequency of the external field, the dose of laser irradiation, temperature and time were investigated by a highly sensitive physicochemical method -the method of dielectric losses. This article examined the impact of laser radiation on the dielectric properties of polymethylmethacrylate at frequency of 50 kHz within the temperature interval from 170 to 420 K. The authors showed that the processing of the samples with laser radiation leads to substantial changes in the dielectric constant and tangent of dielectric loss angle.

Multifunctional modifier for regulating the properties of concrete mixtures

The purpose of this work is the synthesis of new highmolecular surfactants polyalkylacrylates and the establishment of correlations between their colloidal chemical properties. Well-known methods for the synthesis and determination of the properties of surfactants were used. New high molecular surface-active substances (HMSAS) were obtained based on the reaction of polymer-analogous transformations. The resulting copolymers contain side hydrocarbon radicals of various lengths. Polyalkylacrylates were obtained by esterification with aliphatic alcohols (butyl, octyl, decyl) in a mixture of organic solvents and the presence of a catalyst, sulfuric acid. The surface activity and foaming ability of the obtained new HMSAS in aqueous solutions have been studied. The results obtained showed that with an increase in the length of the aliphatic hydrocarbon radical in the chain of macromolecules, the surface activity of polyalkylacrylates increases. An analysis of the results showed a good correlation between foaming and surface activity of the investigated HMSAS. Based on research, it was found that the stability of the foams is largely determined by the interaction of the HMSAS molecules in the monolayer.

REGENERATION OF ULTRAFILTRATION MEMBRANES IN THE PROCESS OF SEPARATING OIL-WATER SYSTEMS

It is proposed to use a baromembrane process for the purification of spent oil-containing products. Tubular ultrafluorescence polymer membranes with an active layer of fluoroplast with diatomite additives and ceramic membranes based on Al2O3 were used as filter elements. During the operation of membrane elements, there is a drop in specific productivity associated with their contamination. Contamination of ultrafiltration membranes is considered as irreversible deposition of high-molecular substances, petroleum products and fats on the surface or in the pores of the membrane. However, with proper technical operation, it is possible to increase the service life of the membranes. The paper considers two strategies for maintenance of membrane elements based on their washing (regeneration) at certain intervals. The choice of the method and mode of regeneration of membrane elements is determined depending on the type of membrane material and on the specific operating conditions of their operation. For the regeneration of polymer tubular membranes due to their anisotropic design and the fragile connection between the active (fine-porous) and drainage (coarse-porous) layers, a chemical washing method using kerosene as a reagent is proposed. For ceramic membranes, due to the peculiarities of their production by sintering at high temperatures, two regeneration methods are possible: physical and chemical. The physical method consisted in using permeate backwash of membrane pores. Experiments have shown that it is most effective to regenerate membrane elements with a 30% drop in specific productivity by backwash, since it does not require the use of additional reagents and their subsequent disposal.

Metabolomic profiling upon external digestion in larvae of diving beetles: Cybister Curtis, 1827, Dytiscus Linnaeus, 1758, and Hydaticus Leach, 1817 (Coleoptera: Dytiscidae)

The SDS–PAGE analysis of prey animals (fly larvae) during external digestion by aquatic predators, the larvae of selected species in dytiscid genera, showed a major component of protein with a molecular weight of ca. 20 kDa. In addition, the analysis of third instar larvae of Cybister brevis Aubé, 1838, by nanoLC–ESI–Q-TOF/MS/MS revealed that the digested body fluid includes a polypeptide with a sequence of 97 amino acids corresponding to hemocyanin N (51% matched by Mascot and BLAST searches) and hemocyanin M (12% matched) derived from flies. We also found evidence indicating that beetle larvae repeatedly release digestive enzymes at least twice while consuming the fly bodies. These results suggest that the digested polypeptides were derived from ubiquitous high molecular substances such as arylphorin subunit C223 precursor included in the body fluid of the fly (Calliphora vicina Robineau-Desvoidy, 1830) that were produced during external digestion by diving beetle larvae.

Development of a hardware configuration and a calculating program for a membrane plant equipped with polarization layer separation units

Various types of membrane units, including standard units for permeate separating, which are currently used for various liquids processing, are considered. Their advantages and disadvantages, working conditions and operating features are assessed. The principle of operation of membrane units with the bleed of the polarization layer is analyzed. A distinctive feature of such devices is the separation of the feed stream into three parts: adjacent to the membrane, including a polarization layer, with an increased concentration of high molecular substances (HMS) – concentrate, a spent stream core to be re-processed – retentate, and permeate, that practically contains no HMS. The unit scheme and the principle of operation of the plant completed with this equipment are given. A feature of this plant is the parallel arrangement of the membrane devices. In this configuration of the plant, there are two flow circulation loops and two tanks, in one of which there will be a depleted solution, in the other the retentate. During operation, the circulation of the depleted flow is provided. In this case, the resulting polarization layer (concentrate) will be discharged into the second tank. The working process continues until the complete depletion of the solution in the first tank. In the event that the solution in this tank is exhausted, and the required concentration of the product has not been reached, the second tank with the concentrate activates and the process continues. The principle of operation in this case is similar. The rotation of tanks continues until the required degree of concentration of the product is obtained. A calculation algorithm, a block diagram and a program for calculating the operating time of a membrane installation are proposed, for which a certificate of state registration of a computer program has been obtained. The calculation algorithm and program interface are presented. This program makes it possible to predict the operation of such installations and provides for the possibility of optimizing their operation.т.п.)

Influence of aldol condensation processes on the formation of surface films during friction in ester lubricants

The boundary lubrication mode is usually implemented in conditions of low sliding speeds and high loads. The formation of strong boundary lubricating films under this friction mode determines the operability and durability of the friction units. It is believed that the formation of surface boundary films during friction includes the stages of the lubricant oxidation, and the aldol condensation reaction of oxidized molecules. As a result, high-molecular substances called “friction polymers” are formed. The paper studies the formation of surface films in the presence of substances with different reactivity in the aldol condensation and Claisen condensation reactions. Sunflower oil, bis (2-ethylhexyl) sebacate (DEHS), triisodecyl benzene-1,2,4-tricarboxylate (TC) were used as lubricants. It is shown by ATR IR-spectroscopy of that the common thing for the studied oils is that the C=O and C-O groups participate in the formation of boundary films in these oils. The addition of substances, active in aldol condensation reactions, into lubricants does not accelerate the formation of boundary films. Additives that can chemically interact with iron contribute to the dissolution of the surface oxide film and accelerate the formation of boundary layers. The formation of “friction polymers” occurs when the lubricant molecules interact with the metal surface.

Influence of enzymative catalysis on technological parameters of apple juice production

The article provides data on the investigation of the effect of enzymatic catalysis on the technological parameters of apple juice production. Apples are distinguished by the presence of a heterogeneous high-molecular complex of biopolymers, which complicates their processing: it prevents juice output, hinders its clarification, filterability of wine materials and negatively affects the colloidal stability of wines. Enzymatic catalysis based on the action of microbial preparations, contributes in many respects to the successful solution of the problems of intensifying technological processes of fruit and berry raw materials processing and improving the quality of obtained products. Enzyme preparations of complex action, causing deep hydrolysis of high-molecular components of the peel and pulp of fruits, provide a more complete extraction of the liquid fraction, better clarification and filterability of juices. The foothill zone of Adygea has special soil and climatic conditions that affect the formation of physical and chemical characteristics of raw materials. Considering that apple tree occupies the first place in terms of planting area among fruit crops in the Republic of Adygea, an urgent task is to study the effect of enzymatic catalysis on technological properties of juices obtained during the processing of apples grown in these soil and climatic conditions. Enzyme preparations of complex action, recommended for the processing of fruit juices and wine materials, made in France and Germany, have been selected as objects of the research. The results of the studies on the use of enzyme preparations in the processing of apple juices, taking into account their influence on the juice yield and such technological parameters as the speed and quality of clarification, filterability and dynamics of alcoholic fermentation, have been presented. The effect of enzymatic catalysis on the mass concentrations of polysaccharides, starch, total nitrogen and phenolic substances has been studied. A higher hydrolytic activity of the Extrazyme enzyme preparation has been established, when added to the pulp; it contributes to the deep transformation of high-molecular substances and, as a result, to optimize the technological parameters of juice production

Injectable and In Situ Gelling Dextran Derivatives Containing Hydrolyzable Groups for the Delivery of Large Molecules.

Recently, we reported the synthesis and characterization of a new dextran derivative obtained by grafting polyethylene glycol methacrylate to a polysaccharide backbone through a carbonate bond. This moiety was introduced because it allows for the fabrication, through a photo-induced crosslinking reaction, of biodegradable hydrogels particularly suitable for the release of high molecular weight molecules. Here, we investigate the influence of the oxyethylene chain length and the molecular weight of the starting dextran on the main properties of the polymeric solutions as well as those of the corresponding hydrogels. All synthesized polymeric derivatives were characterized by FTIR, NMR, and rheological analyses. The photo-crosslinking reaction of the polymers allowed us to obtain biodegradable networks tested for their mechanical properties, swelling, and degradation behavior. The results showed that both the oxyethylene chain length as well as the molecular weight of the starting dextran influenced swelling and degradation of the hydrogel network. As a consequence, the different behaviors in terms of swelling and degradability were able to affect the release of a large model molecule over time, making these matrices suitable candidates for the delivery of high molecular weight drug substances.

Bioprocessing of wheat to produce food and technical products

The article presents the parameters and conditions for the formation of gluten in the laboratory. The influence of some technological parameters in the preparation of water-powdery suspension on the yield of gluten was studied. It was found that for the formation of a strong gluten skeleton, the temperature must be 50 ° C, the duration of the batch - 30 minutes, and the hydromodule - 1.5:1. It is under these conditions that the binding of the gluten and gliadin protein fractions in the gluten frame. It is proved that due to cellulolytic enzyme preparations, sequential hydrolysis of non-starch polysaccharides to glucose is carried out, as well as dispersion of starch and other high-molecular substances in the grain composition. This increases the quantity of fermentable substances and increases the quantity of alcohol produced. Processing of wort obtained after extraction of gluten from water-flour suspension results in higher ethanol concentration, glucose fermentation rate, and ethanol production rate. In addition, gluten can be used as a value-added by-product in a wheat-based bioprocessing plant, which significantly increases the cost-effectiveness of the process.

COMPLEX OF ENZYMES FOR EFFICIENT CONVERSION OF DRIED APRICOT BIOCOMPONENTS IN THE PRODUCTION OF FOOD INGREDIENTS FOR ALCOHOLIC BEVERAGES

The effectiveness of the use of pectolytic enzyme preparations - Fructocim P6L and fungal cellulase - Bruzaym BGX for biocatalysis of high-molecular substances of dried apricot pulp in the preparation of food ingredients (alcoholic juices and fruit drinks) for alcoholic beverages is shown.

Comparative analysis between asphaltites and extra heavy oil asphaltenes

The asphaltite material receives many names depending on the country, or area of knowledge, for this reason it is also known as bitumen, asphalt and gilsonite, its composition is a mixture of high molecular weight organic substances, mainly polyaromatic compounds characterized by a black color, and they appear in a semi-solid or solid state. Asphaltenes correspond to the oil fraction with the highest molecular weight, this characteristic provides a high viscosity to hydrocarbons, which contain, in their composition, a concentration equal to or greater than 10%, although the exact structure of this is not known. molecular family, it has been possible to elucidate the functional groups present, such as carbonyl acids, thiols and pyridines, implying the presence of heteroatoms, such as nitrogen, sulfur and oxygen, but the most characteristic part of this type of molecules is their nucleus polyaromatic, which can contain up to 20 or more benzene rings. A sample of Colombian asphaltite was taken and compared with a sample of asphaltenes from a Colombian extra-heavy crude, solubility tests, a spectroscopic characterization by Ultraviolet-Visible, infrared, a thermal evaluation by Thermogravimetry and Differential Scanning Calorimetry were carried out., in addition to an analysis by X-ray diffraction, in order to determine if the behavior and composition of both The objective of this investigation is to be analyzed by comparing a traditional asphaltite and an asphaltite, if the latter has the same properties and composition, with a view to being used as an energy source. The results obtained reveal that despite the fact that both substances present a similar composition, their glass transitions are different, as well as the crystalline phases present in each of the materials.

Comparison of changes in albumin binding capacity during hemodiafiltration or hemodialysis with middle cut off membranes

Albumin is important for the transport of protein-bound substances (PBS). Albumin binding capacity (ABiC) is reduced in dialysis patients. This can contribute to worsening of uremic symptoms. It is presumed that open-porous middle cut off filters that is, HDx (Baxter-Theranova) remove high molecular substances more efficiently than conventional treatment. To evaluate HDx for the improvement of ABiC and removal of PBS, HDx was compared to hemodiafiltration (Fresenius-FX80, HDF). We included 32 chronic patients on HDF. After inclusion patients were treated with HDx for 14 days. Blood samples were drawn before/after treatments at study entry, first HDx and sixth HDx, to determine ABiC and other study parameters. ABiC improved in HDx (68.4% vs 72.4%) and HDF (69.9% vs 72.4%) without differences between both therapies. No reduction of albumin concentration during HDx treatment was observed. HDx is accepted as a safe and equally efficient therapy for removing albumin bound uremic toxins compared to HDF with high flux dialyzers.

Characterisation of Recombinant Human Erythropoietin Obtained from CHOpE—Erythropoietin Producing Strain of Chinese Hamster Ovary Cells

Development and implementation in clinical practice of recombinant human erythropoietins (rhEPOs) remain a priority task today. Additional studies were performed in order to obtain clinical trial authorisation for rhEPO tablets for oral use. The studies were aimed to demonstrate the suitability of the erythropoietin producer strain based on Chinese hamster ovary cells (CHOpE) for the production of rhEPO, and the compliance of the substance characteristics with the requirements for erythropoietin (EPO).The aim of the study was to characterise the rhEPO substance obtained from the CHOpE strain cells in accordance with the requirements for EPO.Materials and methods: the rhEPO substance was obtained by culturing the strain of Chinese hamster ovary cells—CHOpE. The expression construct of the producer strain was evaluated using methods for determination of nucleotide and amino acid sequences. The Sanger method was used to perform sequencing of the nucleotide sequence encoding the human EPO gene. The amino acid sequences of the rhEPO molecule C- and N-termini were determined by the Edman method. The copy number of the EPO gene in CHOpE cells was determined by real-time polymerase chain reaction. The properties of the rhEPO substance were evaluated in accordance with the requirements for EPO. Isoelectric focusing, peptide mapping, and polyacrylamide gel electrophoresis were used for identification of the rhEPO substance. The ratio of isoform composition was determined by capillary electrophoresis. Dimer impurities and high molecular weight related substances were determined by high-pressure liquid chromatography. The content of protein and residual nucleic acids was determined by spectrophotometry. The concentration of the rhEPO substance was assessed by enzyme immunoassay.The results of the study confirmed genetic stability of the CHOpE producer strain and demonstrated identity of N- and C-terminal amino acid sequences of the rhEPO molecule to those of the natural EPO. The CHOpE producer strain was used to obtain a rhEPO substance which is homogenous and does not contain impurities of EPO oligomeric forms. Dimers and high molecular weight related substances account for less than 0.5%. The rhEPO molecular weight ranges from 32 to 38 kDa, and the isoelectric point is within 2.8—4.15. The study identified the peaks of isoforms 1–8, the isoform composition of the rhEPO substance corresponds to that of EPO. It was determined that 1 mol of the substance contains 13.75 mols of sialic acids.Conclusions: the study confirmed the suitability of the CHOpE producer strain for the production of rhEPO. The obtained rhEPO substance meets requirements for EPO.