Low Molecular Weight Organic Compounds Research Articles

Seasonal distributions and possible sources of low molecular weight organic acids in PM2.5 from a typical mining city after decade green mining developing in Southeastern Hubei, Central China

Low molecular weight (LMW) organic compounds are prevalent in the atmospheric aerosols. Human activities and natural sources could significantly influence aerosol compositions and concentrations, particularly in a typical mining and metallurgy city. In this study, we measured dicarboxylic acids, ω-oxocarboxylic acids, pyruvic acid, α-dicarbonyls, and fatty acids in PM2.5 from Huangshi, China throughout one year. The results indicated that oxalic acid and glyoxylic acid were the most abundant dicarboxylic acid and ω-oxocarboxylic acid, respectively, across all seasons. Following nearly a decade of environmentally conscious economic development in Huangshi, it is observed that organic compounds primarily accumulated in PM2.5 due to the combustion of fossil fuels for mining-related activities and biogenic emissions. Furthermore, anthropogenic activities, including emissions related to traffic, biomass burning, and plastic incineration, significantly influence the composition of organic aerosols. Natural processes, such as atmospheric oxidation during long-distance transport, predominantly from North China, Mongolia, Russia, and Kazakhstan, also play a substantial role. The findings underscore the transitioning energy structures, modes of transport, and oxidation processes during long-distance transport have already begun to influence the composition of LMW organic compounds. The insights gained from this study offer valuable information for researchers and governmental authorities to understand the molecular composition and potential sources of LMW organic acids in the context of green mining development. This knowledge can aid in the formulation of targeted policies for the prevention and control of carbonaceous pollution in similar mining regions globally.

COMPARATIVE CHARACTERISTICS OF THE LOW MOLECULAR WEIGHT METABOLOME OF MACROPHYTES IN DIFFERENT WATER BODIES IN THE WATER AREA OF THE KANDALAKSHA BAY OF THE WHITE SEA

The Kandalaksha Bay of the White Sea underwent a first-of-its-kind comparative examination of the composition of essential oils of structure-forming macrophytes growing in freshwater and saltwater habitats. The essential oils of the aquatic macrophytes Nuphar lutea (L.) Sm., Ruppia maritima L., Zostera marina L., Fucus vesiculosus L., and Ascophyllum nodosum (L.) Le Jolis were obtained by steam hydrodistillation using the Clevenger apparatus from dried plants. Gas chromatography-mass spectrometry (GC/MS complex SHIMADZU GCMS-QP2010 Ultra) was used to analyze the qualitative and quantitative composition of LMWOCs (low molecular weight organic compounds). The component composition of the low molecular weight metabolome (LM) of macrophytes was shown to depend on both plant species specificity and plant habitat conditions (hydrological features, trophic state). More LMWOCs are found in plants from freshwater habitats than from marine ones. The investigated plants had only a few major compounds, ranging in number from 4 to 14. They accounted for between 70 and 83% of the overall concentration of all compounds in freshwater N. lutea and between 82 and 95% of the total concentration of LMWOCs in marine macrophytes. The most significant (% of the total essential oil) main components in macrophytes were carboxylic acids, specifically hexadecanoic, tetradecanoic, linoleic, and linolenic. The outcomes gained proved that the presence of carboxylic acids is a sign of a healthy macrophyte environment. The composition of LM of plants from northern habitats (marine and freshwater) contains high total concentrations of LMWOCs (including valuable ones from the perspective of economic use), making it possible to consider them as a valuable natural renewable resource for obtaining raw materials for various economic uses.

Elucidation of biopotentiators in organic based formulation bijamrith from Gir Cow (Bos indicus) excrements and urine using GC-MS

Background: Traditional organic formulation bijamrith prepared from fresh urine and dung of cow is an important element in natural farming and extensively applied in modern agriculture practices to improve the soil fertility, control pest and disease in plants. The scientific validation of the biologically active compounds in bijamrith is unexplored. Methods: Bijamrith was prepared from excrements of Gir cow. Since, the volatile low molecular weight organic compounds from cow wastes could be derived from the solvent extract using GC-MS effectively, the compounds were separated by liquid-solvent extraction method using diethyl ether solvent and analyzed by GC-MS. Result: GC-MS analysis revealed the elution of about 40 different compounds in bijamrith formulation. Among them, fatty acid namely 9-octadecenoic acid (Z)-, an ester compound 2,3-dihydroxypropyl occupied higher concentration with peak area of 13.96% at 29.29 minutes of retention time which were reported to possess antifungal, antibacterial and anti-inflammatory activity. The other biologically active compounds eluted were antioxidants, plant growth hormones, nematicidal agents for defense mechanism and improvement of plant health.

Introduction to small molecule drug discovery and preclinical development

Over 90% of marketed drugs are small molecules, low molecular weight organic compounds that have been discovered, designed, and developed to prompt a specific biological process in the body. Examples include antibiotics (penicillin), analgesics (paracetamol) and synthetic hormones (corticosteroids). On average, it takes 10–15 years to develop a new medicine from initial discovery through to regulatory approval and the total cost is often in the billions. For every drug that makes it to the market, there are many more that do not, and it is the outlay associated with abortive efforts that accounts for most of this expense. The discovery of new drugs remains a significant challenge, involving teams of researchers from chemistry, biology, drug development, computer science and informatics. In this article we will discuss the key concepts and issues encountered in small molecule preclinical drug discovery and introduce some of the emerging technologies being developed to overcome current obstacles.

Gas Chromatography-Mass Spectrometric Study of Low-Molecular-Weight Exogenous Metabolites of Algae-Bacterial Communities in the Laboratory Accumulative Culture

The study of exogenous metabolites of algae-bacterial communities in the laboratory accumulative culture obtained from natural river water was conducted using gas chromatography-mass spectrometry. Exometabolites of the algae-bacterial community (including microalgae and cyanobacteria) in the culture medium were represented by saturated, unsaturated, and aromatic hydrocarbons, carboxylic acids, phenolic, and terpene compounds and their derivatives. Possible biological activities of the discovered exometabolites are considered. The study has demonstrated that an increase in the number of main groups of microorganisms, along with changes in the composition of algae and cyanobacteria, are responsible for the increase in the composition and concentration of metabolites in the microecosystem’s culture medium after one month of cultivation. The presence of octacosane in high concentration (0.0603 mg/L; 23.78% of the total content of low molecular weight organic compounds) by the end of exposure accumulative culture is associated with the strong development of the cyanobacterium Gloeocapsa sp. in the presence of diatom algae of the genus Navicula and green algae of the genera Chlorella and Scenedesmus. Due to the need to comprehend the ecological and biochemical mechanisms of the formation and functioning of algae-bacterial communities, as well as to predict potential paths of transformation and evolution of aquatic ecosystems, the specificity of exometabolite complexes of algae and microorganisms, as well as their allelopathic and other biochemical interactions in freshwater ecosystems, requires further serious study.

CHEMICAL COMPOSITION AND BIOLOGICAL PROPERTIES OF THE KIDNEYS OF POPULUS NIGRA L. OF THE CASPIAN REGION

The chemical composition of low molecular weight organic compounds (NOS) was studied by chromatography-mass spectrometric analysis of Populus nigra L. kidneys. Of the Caspian region and comparative antimicrobial (bactericidal) activity of extractive components with other plants with characteristic antimicrobial properties. The extraction was carried out by percolation in water-alcohol solutions. The study of antimicrobial activity was carried out by the standard CFU method. As a result, 49 compounds were identified, of which 10 remained unidentified. The study of comparative antimicrobial properties of plant extracts showed the complete bactericidal activity of Populus nigra kidneys against opportunistic microorganisms and microflora of air and water, in MIC equal to 0.25 micrograms/ml. Therefore, the NOSES isolated from the kidneys of Populus nigro of the Caspian region have prospects for further study of antioxidant activity for the preparation of biotechnological drugs and pharmaceutical substances.

In vivo polyamine applications to globe artichoke: Effects on plant growth-development and some bioactive components

The globe artichoke, Cynara cardunculus var. scolymus (L.), is an important member of the Asteraceae family, being used as a food and due to it has certain health-improving qualities in the treatment of various disorders since ancient times. Low molecular weight organic compounds with a role in several crucial cellular and physiological processes of plants are known as polyamines. They participate in processes such as cell division, differentiation, and growth, the sprouting of seeds, root formation, and flower and fruit development. They have been identified as particularly efficient against biotic and abiotic stress factors. The present research aimed that the evaluation of effects of various polyamine (PA) types and concentrations on three different artichoke cultivars by biometric measurements and biochemical analyses. For this purpose, seedlings of three artichoke cultivars (‘Sakız OP’, ‘Bayrampaşa OP’, and ‘Olympus F1’) were sprayed with various concentrations (0, 50, 100 and 250 mg L-1) of three distinct types of significant polyamines, including putrescine, spermidine, and spermine. Several growth parameters were examined in the current research. The effects on the total phenol and antioxidant capacities, as well as changes in the amounts of cynarin and 1,5-O-dicafeoylquinic acid, were also evaluated. The results revealed that there were statistically differences based on cultivars and treatment concentrations. Among the three forms of PA spermine was potent at increasing total phenolic content, while putrescine was effective at increasing total antioxidant content. On the other hand, putrescine, spermine and, spermidine had no positive effects on cynarin and 1,5-O-dicaffeoyquinic acid levels. Results clearly revealed that each biometric data and biochemical content could not be determined by a single polyamine type and concentration. It can be concluded that to improve the biometric values and biochemical content are depending on cultivar and dosage of various PAs.

Use of carbon-13 NMR to identify known natural products by querying a nuclear magnetic resonance database-An assessment.

The quick identification of known organic low molecular weight compounds, also known as structural dereplication, is a highly important task in the chemical profiling of natural resource extracts. To that end, a method that relies on carbon-13 nuclear magnetic resonance (NMR) spectroscopy, elaborated in earlier works of the author's research group, requires the availability of a dedicated database that establishes relationships between chemical structures, biological and chemical taxonomy, and spectroscopy. The construction of such a database, called acd_lotus, was reported earlier, and its usefulness was illustrated by only three examples. This article presents the results of structure searches carried out starting from 58 carbon-13 NMR data sets recorded on compounds selected in the metabolomics section of the biological magnetic resonance bank (BMRB). Two compound retrieval methods were employed. The first one involves searching in the acd_lotus database using commercial software. The second one operates through the freely accessible web interface of the nmrshiftdb2 database, which includes the compounds present in acd_lotus and many others. The two structural dereplication methods have proved to be efficient and can be used together in a complementary way.

Modeling the Migration Behavior of Extractables from Mono- and Multilayer Polyolefin Films to Mathematically Predict the Concentration of Leachable Impurities in Pharmaceutical Drug Products. Part 2: Conservative Diffusion and Partition Coefficient Determinations.

In the development of a pharmaceutical drug product packaging, an important step is to demonstrate acceptable levels of leachable impurities migrating from the packaging material into the drug product during its shelf life and therapeutic use. Such migration processes can be quantified either by analytical methods (which is often challenging and labor intensive) or (in many cases) through theoretical modeling, which is a reliable, quick, and cost-effective method to forecast the level of leachable impurities in the packaged drug when the diffusion and partition coefficients are known. In the previous part, it was shown how these parameters can be determined experimentally, and subsequent theoretical fitting of the results for a series of low- and high-molecular-weight organic compounds (known leachables) in a series of polyolefin materials was performed. One of the interpretations of these results is that a theoretical calculation can be made only for organic compounds and materials whose diffusion/partition/solubility coefficients were determined experimentally and theoretical fitting was achieved. However, in practice, there will be situations in which other leachable compounds may have to be investigated. In such cases, strictly speaking, it would be necessary to perform the whole experimental and fitting procedure for the new compound before a proper theoretical modeling is possible. But this would make the theoretical calculation of a leaching process from a pharmaceutical packaging material a cumbersome and cost intensive procedure. To address this problem, the pools of diffusion and partition coefficients were used to develop an approach that allows the estimation, without any additional experimentation, of so-called "conservative" diffusion and partition coefficients for a much wider range of potential leachables in the polyolefin pharmaceutical packaging materials and aqueous solutions investigated previously.

Emission characteristics and optical properties of brown carbon during combustion of pine at different ignition temperatures under high-time resolution

Biomass burning is a major contributor to atmospheric brown carbon (BrC). However, the properties of BrC from biomass burning can vary significantly based on combustion conditions and stages. To investigate these variations, we simulated the combustion cycle of pine at three different ignition temperatures (400, 600 and 800 °C) in a quartz tube furnace. Highly time-resolved samples were collected to analyze the emission and light-absorption properties of BrC during different combustion processes. Our findings revealed that the absorption emission factor at 370 nm was highest at 800 °C (14.96 ± 6.15 g·m−3) and lowest at 600 °C (3.48 ± 1.05 g·m−3). At lower combustion temperatures, we observed a higher content of low molecular weight organic compounds in BrC (OC1, OC2). Furthermore, the emission and light-absorption properties of BrC varied significantly throughout the combustion cycle, with clear bimodal distributions observed for OC, EC, and mass absorption efficiency at 365 nm at all three temperatures. The unimodal distribution of the absorption Ångström exponent indicated that highly aromatic BrC molecules were mainly produced at the beginning and end of the combustion events. We also found that low volatile OC components (OC3 + OC4) had a dominant effect on the variation in MAE365 at 400 and 600 °C, while high volatile OC components (OC1 + OC2) were more significant at 800 °C. These results suggest that the optical properties of BrC components can vary significantly depending on ignition temperature.

Visible light photocatalysis alleviates ceramic membrane fouling caused by intracellular organic matter of Microcystis aeruginosa

Ultrafiltration (UF) is an effective technology for treating algae-containing water. The algal intracellular organic matter (IOM) released by dead algae during an excessive algae growth phase causes more serious membrane fouling than viable algal cells and algal extracellular organic matter (EOM), which seriously restricts stable operation of UF. This paper studied the removal of IOM by a Bi2O3–TiO2/PAC (Bi-doped TiO2 nano-composites supported by powdered activated carbon) photocatalytic oxidation-ceramic ultrafiltration membrane, the inhibitory effect of membrane fouling at different photocatalytic oxidation times, and the fouling mechanism. The results show that both the adsorption and photocatalytic oxidation of Bi2O3–TiO2/PAC can significantly remove proteinoids and humic acid-like fluorescent components present in IOM, with removals of UV254 and DOC reaching up to 81.8% and 44.0%. The generated superoxide radicals and hydroxyl radicals positively affect the degradation of organic compounds of various molecular weights, and holes mainly degrade acidic low-molecular weight organic compounds. When the photocatalytic oxidation time was extended to 60 min, the membrane flux increased by 70.7% and the reversible resistance and irreversible resistance decreased by 83.4% and 90.1%, respectively. Under these conditions, the fouling mechanism changed from complete blockage to intermediate blockage. In the late stage of photocatalytic oxidation (90–120min), part of the high and medium molecular weight organic components were oxidized to produce low-molecular weight organic compounds (LMW acidic and neutral organic compounds), and blockage of filter cake became the main fouling mechanism. After photocatalysis, the zeta potential decreases significantly and the interaction forces between pollutants and pollutants are transformed into repulsive forces. Application of an appropriate photocatalytic oxidation time can alleviate the ultrafiltration membrane fouling caused by algal-derived organics.

Solid phase extraction of ocean dissolved organic matter with PPL cartridges: efficiency and selectivity

Our current knowledge of the chemical composition of ocean dissolved organic matter (DOM) is limited, mainly because of its extreme molecular diversity, low concentration of individual compounds and the elevated ionic strength of ocean waters. As a result, many analytical methods require a previous extraction step. The efficiency and selectivity of the extraction method defines the representativeness of the extracted DOM fraction. Nowadays, the most widespread procedure for concentrating DOM is solid phase extraction (SPE) using styrene divinyl benzene polymer cartridges (PPL). Here, we investigate the effect of SPE-PPL on DOM elemental and optical properties to assess the efficiency and selectivity of this extraction method on water samples from the main intermediate and deep water masses of Arctic, Mediterranean and Antarctic origin present in the Cape Vert Frontal Zone (CVFZ, NW Africa). Furthermore, North and South Atlantic Central waters converge in this area and coastal DOM is injected by the giant upwelling filament of Cape Blanc. On one side, the colored fraction of DOM (CDOM) presented extraction efficiencies comparable to that of the bulk dissolved organic carbon (DOC), but decreased significantly with increasing wavelength, suggesting an affinity of PPL cartridges for low molecular weight organic compounds. While the protein-like fluorescent fraction of DOM (FDOM) was also extracted with the same efficiency than DOC, the extraction efficiency of the humic-like fraction was comparatively much higher. On the other side, dissolved organic nitrogen (DON) extraction efficiencies were about half that of DOC. These contrasting extraction efficiencies of the different DOM pools indicated that the extracts were enriched in N-poor, low molecular weight and recalcitrant DOM, therefore showing less variability than the corresponding bulk DOM. Furthermore, DOC, DON, CDOM and FDOM extracted were not homogeneous through the water column but displayed certain significant differences among water masses in both efficiency and selectivity.

Influence of oxygen, UV light and reactive dissolved organic matter on the photodemethylation and photoreduction of monomethylmercury in model freshwater

The key factors which affect the abiotic photodemethylation process of monomethylmercury (MMHg) in the freshwaters has remained unclear. Hence, this work aimed to better elucidate the abiotic photodemethylation pathway in a model freshwater. Anoxic and oxic conditions were implemented to investigate the simultaneous photodemethylation to Hg(II) and photoreduction to Hg(0). MMHg freshwater solution was irradiated through exposure to three wavelength ranges of full light (280–800 nm), without short UVB (305–800 nm), and visible light (400–800 nm). The kinetic experiments were performed following dissolved and gaseous Hg species concentrations (i.e., MMHg, iHg(II), Hg(0)). A comparison between two methods of post-irradiation purging and continuous-irradiation purging confirmed MMHg photodecomposition to Hg(0) is mainly induced by a first photodemethylation step to iHg(II) followed by a photoreduction step to Hg(0). Photodemethylation under full light extent normalized to absorbed radiation energy showed a higher rate constant in anoxic conditions at 18.0 ± 2.2 kJ−1 compared to oxic conditions at 4.5 ± 0.4 kJ−1. Moreover, photoreduction also increased up to four-fold under anoxic conditions. Normalized and wavelength-specific photodemethylation (Kpd) and photoreduction (Kpr) rate constants were also calculated for natural sunlight conditions to evaluate the role of each wavelength range. The relative ratio in wavelength-specific KPAR: Klong UVB+ UVA: K short UVB showed higher dependence on UV light for photoreduction at least ten-fold compared to photodemethylation, regardless of redox conditions. Both results using Reactive Oxygen Species (ROS) scavenging methods and Volatile Organic Compounds (VOC) measurements revealed the occurrence and production of low molecular weight (LMW) organic compounds that are as photoreactive intermediates responsible for MMHg photodemethylation and iHg(II) photoreduction in the dominant pathway. This study also supports the role of dissolved oxygen as an inhibitor for the photodemethylation pathways driven by LMW photosensitizers.

Pterin interactions with gold clusters: A theoretical study

Gold (Au) nanoclusters (NCs) are novel materials with low cytotoxicity and high chemical stability. These properties are in high demand during the bioimaging. Moreover, the optical properties of gold clusters allow to use them as colorimetric and luminescent bionanosensors. Pterins are low molecular weight organic compounds, which are used in medicine as biomarkers of phenylketonuria, vitiligo, inflammation and immune system activation, cancer, COVID-19, etc. We have investigated the possibility of gold nanosensors usage to detect pterin (Ptr). Ptr-Aunq structures (n = 1–6; q = 0–2) Gibbs energy of complexation (Eb) have been obtained using density functional theory. The highest Eb was determined for the complexes of Au62+ and Au32+ in acidic and alkaline aqueous solution, respectively. The detection of pterin with gold clusters seems to be prospective using both colorimetric and fluorescent detection because of the intense S0→S1 transition in the absorption spectrum of the Au5+ complex. Raman detection of pterin should be performed at alkaline pH because of the dramatic changes in the spectrum of Ptr−1 upon the addition of Au clusters. We believe that these tunable changes of the pterin spectra due to Au clusters and nanoparticles attachment could be exploited in further studies on nanosensor design.

Generation and properties of organic colloids extracted by water from the organic horizon of a boreal forest soil

Organic colloids are an important part of dissolved organic matter (DOM) yet many of their properties remain elusive. The main aims of this study were to assess how the colloidal properties of DOM extracted with water from an organic boreal soil horizon varied with the extraction protocol, and thereby provide insight into the nature of the DOM colloids and develop a mechanistic understanding of how the colloids were generated from the parent soil aggregates. This was accomplished by systematic variations of extraction temperature (4 °C–100 °C), time, mechanical agitation, and pH, together with a combination of chemical analyses, and light and X-ray scattering. Our results agreed with the previous identification of two main colloidal DOM species, one fractal cluster and a second, smaller colloidal DOM species described as chains or coils. Fractal clusters completely dominated the colloidal DOM in extracts from our soil at room temperature and below. Colloidal coils only existed in DOM extracted above room temperature, and their amount increased significantly between 50 °C–100 °C. Moreover, the temperature variation indicated that the fractal clusters partly dissolved into colloidal coils at elevated temperatures. Mechanical agitation at 4 °C significantly increased the amount of DOM extracted, increasing the concentrations of both fractal clusters and low-molecular weight organic compounds. While the clusters were extracted from agitated and non-agitated soil suspensions, the low molecular weight organics were mainly released by agitation. Based on the experimental observations, we propose a conceptual model where parent soil aggregates contain the fractal clusters in mobile and occluded forms, and that the occluded clusters co-exist with occluded low molecular weight organics. These occluded forms may be released by mechanical forces, increasing pH and temperature. At higher temperatures, the soil aggregates and the fractal clusters start to break up, and subsequently individual colloidal coils, presumably carbohydrates, disperse in the water phase. The model explains the origin and properties of the fractal clusters that completely dominate the colloidal DOM extracted from our soil at room temperature and below.

Controlling the toxicity of biomass-derived difunctional molecules as potential pharmaceutical ingredients for specific activity toward microorganisms and mammalian cells.

A biomass-derived difuran compound, denoted as HAH (HMF-Acetone-HMF), synthesized by aldol-condensation of 5-hydroxyfurfural (HMF) and acetone, can be partially hydrogenated to provide an electron-rich difuran compound (PHAH) for Diels-Alder reactions with maleimide derivatives. The nitrogen (N) site in the maleimide can be substituted by imidation with amine-containing compounds to control the hydrophobicity of the maleimide moiety in adducts of furans and maleimide by Diels-Alder reaction, denoted as norcantharimides (Diels-Alder adducts). The structural effects on the toxicity of various biomass-derived small molecules synthesized in this manner to regulate biological processes, defined as low molecular weight (≤ 1000 g/mol) organic compounds, were investigated against diverse microbial and mammalian cell types. The biological toxicity increased when hydrophobic N-substitutions and C=C bonds were introduced into the molecular structure. Among the synthesized norcantharamide derivatives, some compounds demonstrated pH-dependent toxicities against specific cell types. Reaction kinetics analyses of the norcantharimides in biological conditions suggest that this pH-dependent toxicity of norcantharimides could arise from retro Diels-Alder reactions in the presence of a Brϕnsted acid that catalyzes the release of an N-substituted maleimide, which has higher toxicity against fungal cells than the toxicity of the Diels-Alder adduct. These synthetic approaches can be used to design biologically-active small molecules that exhibit selective toxicity against various cell types (e.g., fungal, cancer cells) and provide a sustainable platform for production of prodrugs that could actively or passively affect the viability of infectious cells.

Histamine and Serotonin Levels in Bone Marrow Stem Cells Niche as Potential Biomarkers of Systemic Mastocytosis and Myeloproliferative Disorders

Bone marrow studies currently provide a lot of valuable information in the diagnostics of hematological diseases including hematopoietic stem cells disorders. Our studies on low-molecular weight organic compounds in bone marrow stem cell niche in various pathogenic conditions, revealed relatively high variability of histamine levels in different groups of hematological diseases. It was also found that serotonin levels were significantly lower than those typically measured in peripheral blood as well as many have the influence on stem cells proliferative potential. This paper presents findings from quantitative and statistical analyses of histamine and serotonin levels. Bone marrow collected from patients undergoing routine diagnostic procedures for hematological diseases and receiving inpatient treatment were analyzed. Histamine and serotonin levels were measured using hydrophilic interaction liquid chromatography (HILIC) coupled with tandem mass spectrometry. Obtained data were analyzed statistically and correlated with the diagnosed groups of hematological diseases and the parameters of complete blood counts. Histamine was found in all tested samples, including those from patients without malignancy, and the reported levels were comparable to the reference values in blood. This observation allows us to assume that bone marrow cells can produce and accumulate histamine. Moreover, the statistical analysis revealed a significant relationship between histamine levels and diagnosed mastocytosis, and between histamine levels and myeloproliferative neoplasms. Different results were obtained for serotonin, and its concentrations in most cases were below the limit of quantification of the method used (< 0.2 ng/mL), which can only be compared to peripheral blood plasma. In a few cases, significantly higher serotonin levels were observed and it concerned diseases associated with an increased number of megakaryocytes in the bone marrow.

COMPONENT COMPOSITION OF ESSENTIAL OIL AND ANTIOXIDANT ACTIVITY OF POTAMOGETON PERFO-LIATUS L. (POTAMOGETONACEAE) GROWING IN THE ASTRAKHAN REGION

For the first time, the component composition of the low-molecular-weight metabolome of perfoliate pondweed (Potamogeton perfoliatus L., family Potamogetonaceae), which grows in the Astrakhan region (lower zone of the Volga river delta), has been investigated. Low molecular weight organic compounds (LMWOCs) in the composition of essential oil were obtained from dried plants by steam hydrodistillation using the Clevenger apparatus. The qualitative and quantitative compositions of the LMWOCs were investigated using gas chromatography-mass spectrometry (GC/MS complex TRACE ISQ (Thermo Scientific) with a quadrupole mass analyzer). The low molecular weight metabolome of P. perfoliatus contained 164 components, of which 151 were identified. Major LMWOCs were carboxylic acids – tetradecanoic (69.7%) and hexadecanoic (10.1%), as well as phytol (3.4%) and phyton (1.4%), characterized by diverse biological activities. The antioxidant activity of an aqueous-alcoholic extract of P. perfoliatus was investigated by a photometric method based on the reaction of DPPH (2,2-diphenyl-1-picrylhydrazyl) dissolved in ethanol with an antioxidant sample. It has been shown that P. perfoliatus extract has more pronounced antioxidant properties than the tested drugs (ascorbic acid and emoxipine). P. perfoliatus from the lower zone of the Volga River delta can be considered as a naturally renewable resource for obtaining raw materials for creating effective composites of new generation algicides to combat cyanobacterial "bloom", as well as for obtaining valuable natural forms of LMWOCs of plant origin for various types of application in pharmacology, medicine, cosmetology, food industry, and other industries.

Effect of sludge retention time on the performance and sludge filtration characteristics of an aerobic membrane bioreactor treating textile wastewater

In this study, the impact of different sludge retention times (SRTs) on the wastewater treatment performance of an aerobic membrane bioreactor (MBR) was investigated using real textile industry wastewater. For this purpose, two laboratory-scale membrane bioreactors were operated in parallel. Under the same conditions, one of the systems was operated at an SRT of 30 d and, the other at SRTs of 20 d, and 10 d, respectively. The total chemical oxygen demand (COD), color and soluble total nitrogen (TN) of the wastewater averaged 927 ± 277 mg/L, 910 ± 287 PtCo and 39 ± 10 mg/L, respectively. COD removal efficiency remained above 90 % in all the tested SRTs. While the color removal efficiency was 55 % and 60 % at SRTs of 30 d and 20 d, respectively, it decreased to 50 % at SRT of 10 d. In addition, the impact of different SRTs on membrane filtration performance was studied. With the reduction of SRT to 10 d, an increase was observed in specific resistance to filtration (SRF) and supernatant filterability (SF) values, while viscosity decreased due to lower suspended solid (SS) concentration. According to gel permeation chromatography (GPC) analysis, the molecular weights of organic substances in the permeate distributed over a wide spectrum as SRT decreased. Also, signals given by the low molecular weight organic compounds were higher.

Acid Gas and Tar Removal from Syngas of Refuse Gasification by Catalytic Reforming

The existence of acid gas and tar in syngas of municipal solid waste gasification limits its downstream utilization as a clean energy source. Here, we investigated the catalytic removal of HCl and tar. The key parameters affecting the catalytic reaction, including space velocity, temperature, the amounts of active metals in the catalyst and the carrier material, were studied, targeting optimized operating conditions for enhanced syngas purification. The morphology, mineral phases, surface area and pore size before and after the reaction were investigated to understand the mechanism to dominate the reaction. The results showed that the removal rate of CaO adsorbent and HCl reached 96% at 400 °C. When the space velocity ratio was 1.0 and the temperature was 400 °C, HCl removal (97%) by NaAlO2 was even better. Nevertheless, clogging was observed for NaAlO2 via the BET test after reaction to jeopardize its durability. A level of 25% Ni doping on Zr1-x(Cex)O2 support provides high stability for tar removal. This is because the Zr1-x(Cex)O2 carrier has higher carbon deposition resistivity than the Al2O3 carrier. The EDX results confirmed that a large amount of C (79.3%) was accumulated on the commercial catalyst surface supported by Al2O3 (25% Ni-based). As for the temperature, a temperature higher than 800 °C could not enhance the efficiency of tar removal, likely due to catalyst deactivation. Carbon deposition and agglomeration are the two main causes of catalyst deactivation. At 800 °C, 25% Ni-based synthetic catalyst can convert 48.5 ± 19.4% tar to low molecular weight organic compounds. By contrast, such a conversion rate under the same temperature only accounted for 5.0 ± 6.8% based on a commercial catalyst. These insights point to the important role of catalyst support materials.