High Molecular Weight Compounds Research Articles

DIDACTIC AND METHODOLOGICAL BASES FOR ENSURING THE STUDY OF CHEMISTRY BY FUTURE SPECIALISTS OF TECHNOLOGICAL AND VOCATIONAL EDUCATION

The article actualizes the research task of substantiating the didactic (content of the leading topics) and methodological (topics and objectives of laboratory work) foundations for ensuring general and professionally oriented competencies in the study of chemistry by future technology teachers and vocational education specialists. It is proposed to include the following topics in the content of training of higher education applicants majoring in 014.10 Secondary Education (Technology): basic concepts and laws of chemistry, periodic law and the D. Mendelieev’s periodic table of chemical elements; main classes of inorganic compounds; hydrocarbons; oxygen-containing organic compounds; non-trogen-containing organic compounds; general properties of high molecular weight compounds; chemical fibers; plastic masses. This block of the discipline includes laboratory work developed by the article author in accordance with the content of each topic. The article concludes the importance of chemical disciplines in the implementation of the educational profiles «Woodworking», «Agricultural Production», «Cooking», «Construction», «Energy», «Design and Modeling of Clothes», «Light Industry», «Design Basics», «Metalworking», etc. in high school in Ukraine.

Seasonal Controls on Microbial Depolymerization and Oxidation of Organic Matter in Floodplain Soils.

Floodplain soils are vast reservoirs of organic carbon often attributed to anaerobic conditions that impose metabolic constraints on organic matter degradation. What remains elusive is how such metabolic constraints respond to dynamic flooding and drainage cycles characteristic of floodplain soils. Here we show that microbial depolymerization and respiration of organic compounds, two rate-limiting steps in decomposition, vary spatially and temporally with seasonal flooding of mountainous floodplain soils (Gothic, Colorado, USA). Combining metabolomics and -proteomics, we found a lower abundance of oxidative enzymes during flooding coincided with the accumulation of aromatic, high-molecular weight compounds, particularly in surface soils. In subsurface soils, we found that a lower oxidation state of carbon coincided with a greater abundance of chemically reduced, energetically less favorable low-molecular weight metabolites, irrespective of flooding condition. Our results suggest that seasonal flooding temporarily constrains oxidative depolymerization of larger, potentially plant-derived compounds in surface soils; in contrast, energetic constraints on microbial respiration persist in more reducing subsurface soils regardless of flooding. Our work underscores that the potential vulnerability of these distinct anaerobic carbon storage mechanisms to changing flooding dynamics should be considered, particularly as climate change shifts both the frequency and extent of flooding in floodplains globally.

Periodic membrane fractionation of freshwater organic matter reveals various reactivity patterns during chlorine/chloramine disinfection

Although drinking water disinfection has significantly reduced mortality from waterborne diseases, the formation of potentially harmful disinfection by-products (DBPs) remains a concern today. These DBPs emerge from the reaction of dissolved organic matter (DOM) with chlor(am)ine during disinfection. Identifying these DBP precursors from heterogeneous and complex DOM mixtures is challenging and to address this, a novel membrane fractionation protocol was developed to isolate and identify the organic DBP precursors from fresh water sources. A tight ultrafiltration and nanofiltration membrane were carefully selected to partition DOM into three molecular weight (MW) fractions: high (>20 kDa), medium (0.3–20 kDa) and low (<0.3 kDa) as defined by high performance-size exclusion chromatography- total organic carbon analysis. A mathematical tool was developed to optimize the fractionation protocol. Therefore, ultrafiltration was executed before nanofiltration and the concentration factor was maximized without inducing fouling to obtain the purest fractions. The mathematical tool was also set in place to predict the necessary diafiltration factor for each individual fractionation experiment based on the initial organic matter composition of the surface water allowing the fractionation protocol to be effective at all times. The protocol was applied to surface water samples collected six times across three seasons yielding a fraction enriched in high MW compounds (up to 50 %), a fraction having more than 80 % of medium MW compounds and a fraction only containing low MW compounds. Although the medium MW fraction showed the highest reactivity for the majority of the investigated DBPs, the low MW fraction showed high reactivity for iodinated trihalomethanes during chlorination and for haloacetonitriles during chloramination. The high MW fraction had the lowest reactivity towards DBPs, which can have important implications for a drinking water treatment since this fraction is generally the most effectively removed by e.g. coagulation, while the more important fractions for DBP formation such as the medium and low MW compounds remain in the water until the disinfection step.

Selective extraction of biomolecules from Saccharomyces cerevisiae assisted by high-pressure homogenization, pulsed electric fields, and heat treatment: Exploring the effect of endogenous enzymes

Saccharomyces cerevisiae contains valuable compounds sought by the industry, prompting the exploration of effective extraction methods. Three physical methods were compared—High-Pressure Homogenization (HPH), Pulsed Electric Fields (PEF), and Heat Treatment (HT)—for releasing diverse bioproducts (amino acids, glutathione, proteins, and mannoproteins) from S. cerevisiae. Treatments (HPH: 2 passes at 100 MPa, PEF: 15 kV/cm for 100 μs (44.9 kJ/kg), HT: 60 °C for 5 min) affected over 90% of S. cerevisiae cells. Despite permeabilization, HT exhibited low efficacy in releasing compounds. HPH led to complete cell disruption, extracting maximum glutathione (1.09 ± 0.04 g/100 gdw) and proteins (68.95 ± 0.96 g/100 gdw) after 2 h. PEF facilitated the gradual extraction of low molecular weight compounds while leaving high molecular weight compounds unreleased initially. After 48 h, 72% of the total protein and amino acid content was released through hydrolysis catalyzed by endogenous yeast proteases. Furthermore, 64.1% of mannoproteins were obtained after 72 h of incubation. This study highlights the efficacy, scalability, and industrial potential of HPH and PEF, demonstrating their ability to produce tailored extracts over time and underscoring the significant role of endogenous enzymes in optimizing extraction yields. These findings provide valuable insights for enhancing efficiency and sustainability in bioproduct extraction from S. cerevisiae.

Baseline polycyclic aromatic hydrocarbon maternal transfer data in Lesser Numbfish Narcine brasiliensis (Elasmobranchii: Batoidea) from an impacted estuary in Southeastern Brazil

Maternal offloading of polycyclic aromatic hydrocarbons (PAHs) poses a significant exposure route for developing embryos, with implications for subsequent generations. Despite known developmental effects regarding fish physiology and behavior, maternal PAH transfer assessments in elasmobranchii are still lacking. This study investigated PAH contamination and maternal transfer in one female Lesser Numbfish (Narcine brasiliensis) electric ray and seven embryos for the first time. Naphthalene was identified as the predominant low molecular weight PAH, and dibenzo[a,h]anthracene was the most abundant high molecular weight compound. Most embryos exhibited some level of PAH exposure, with varying accumulation patterns potentially influenced by size, developmental stage, and yolk absorption rates. Further investigation is warranted to understand the impacts of PAH maternal offloading on elasmobranchii uterine contents and embryos.

Sesquiterpene lactones enriched-fractions obtained from Cynara cardunculus extract diaultrafiltration

Sesquiterpene lactones (SL) are allelopathic compounds that demonstrate great potential of use in sustainable weed management. In this study, membrane processing technology was used for ethanolic Cynara cardunculus leaves extract (CcLE) ultra- and nanofiltration to produce SL-enriched fractions with increased phytotoxic activity. Experiments were conducted to select an ultrafiltration membrane (DuraMem500, DuraMem900 and SuezGH2000) for SL recovery and high molecular weight compounds (MWC) removal. SuezGH2000, which had rejection percentage of 50 % and 88 % for cynaropicrin (Cyn) and chlorophyll, respectively, was used for a sequential purification along with DuraMem200 for lower MWC removal. Since Cyn content on initial feed (11.9 %) and permeate (11.2 %) were similar, as well as phytotoxic activity, the results suggested that DuraMem200 was unsuitable for CcLE fractionation. SuezGH2000 revealed a slight increase on SL content, so, the permeation profile and enhancement of SL content were evaluated. An increase on SL content (36.0–71.0 %) was obtained after 2.3 diavolumes, followed by a decrease between 2.6 and 4.7 diavolumes. Phytotoxic activity evaluations revealed a direct association with SL content with enhancement of activity, particularly at inhibiting shoot growth of Portulaca oleracea. This study revealed SuezGH2000 effectiveness on SL purity improvement on CcLE fractions after 2.3 diavolumes and its potential to be used as a bioherbicide active component.

Partitioning of metals in the tissues and cytosolic fraction of Cerastoderma edule

The concentrations of Cd, Cu and Zn have been determined in the tissues and the cytosolic fraction of the common cockle, Cerastoderma edule, collected from sediments in the Tamar, Plym and Avon estuaries (South West, England). Metal concentrations in the tissues of C. edule from the Avon were lower than those from the Tamar and Plym, except for Cu in the digestive gland. Significant statistical relationships were only obtained between the total sedimentary metal concentrations and Cd in the body of C. edule and Cu in the digestive gland. The cytosolic fraction was extracted from each of the tissues and separated for protein analysis thereby allowing determination of the metal contents in high molecular weight (HMW) compounds, metallothionein-like proteins (MTLP) and very low molecular weight (VLMW) compounds. The digestive glands of C. edule from the Avon had relatively low concentrations of MTLP, whereas MTLP concentrations in the digestive gland of cockles from the Tamar and Plym were higher. The cytosolic fraction of C. edule had relatively low total Cd and Cu concentrations associated with MTLP, whereas Zn was preferentially associated with the HMW and the VLMW components. The results are relevant to metal distributions in C. edule and the role of cytosols in the management of metals by C. edule and other invertebrates.

Early Stage In Vitro Bioprofiling of Potential Low-Molecular-Weight Organoboron Compounds for Boron Neutron Capture Therapy (BNCT)-Proposal for a Guide.

Given the renewed interest in boron neutron capture therapy (BNCT) and the intensified search for improved boron carriers, as well as the difficulties of coherently comparing the carriers described so far, it seems necessary to define a basic set of assays and standardized methods to be used in the early stages of boron carrier development in vitro. The selection of assays and corresponding methods is based on the practical experience of the authors and is certainly not exhaustive, but open to discussion. The proposed tests/characteristics: Solubility, lipophilicity, stability, cytotoxicity, and cellular uptake apply to both low molecular weight (up to 500 Da) and high molecular weight (5000 Da and more) boron carriers. However, the specific methods have been selected primarily for low molecular weight boron carriers; in the case of high molecular weight compounds, some of the methods may need to be adapted.

Matrix- and surface-assisted laser desorption/ionization-mass spectrometry analysis of fingermark components for forensic studies: current trends and future prospects.

The chemical analysis of fingermarks (FMs) has attracted considerable attention in the realm of forensic investigations. Techniques based on direct ionization of a sample by laser irradiation, specifically matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS), have provided excellent figures of merit for analyzing high molecular-weight compounds. However, it can be challenging to analyze low molecular-weight compounds using MALDI-MS owing to potential interference produced by the organic matrices in the low molecular-weight region, which can impede the detection of small molecules (m/z < 700Da). Alternately, surface-assisted laser desorption/ionization-mass spectrometry (SALDI-MS) has shown great promise for small molecules analysis owing to the unique properties of the nanostructures used, particularly, minimal chemical background in low m/z region improved theproduction of ions involved in this method. The advancement of MALDI-MS and SALDI-MS has propelled their application in the analysis of FM components, focused on gaining deep insights into individual traits. This review aims to outline the current role of MALDI-MS and SALDI-MS in the chemical analysis of FMs. It also describes the latest achievements in forensic intelligence derived from fingermark analysis using these powerful methods. The accomplishments include the understanding of certain characteristics and lifestyles of donors. The review offers a comprehensive overview of the challenges and demands in this field. It suggests potential enhancements in this rapidly expanding domain to bridge the gap between research and practical police casework.

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

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

Biogeochemistry of dissolved organic matter and inorganic solutes in soil profiles of tropical pasturelands

Tropical soils play a critical role in the global biogeochemical cycles and are essential for maintaining the Earth's carbon balance. Understanding the dynamics of dissolved organic matter (DOM) is paramount due to its implications for ecosystem functioning and nutrient cycling. This study comprehensively evaluated the origin, distribution, and composition of DOM and inorganic solutes in Brazilian tropical agricultural soils. Multiple analytical techniques were utilized to assess DOM from soil profiles (0–100 cm depth) across a spectrum of land uses, including a native Atlantic Forest, a degraded pasture, as well as intensive grazing, extensive grazing, and silvopastoral systems. Inorganic elements were quantified to assess the coupling between the organic and inorganic biogeochemical cycles. The dominance of C4 carbon in topsoil layers suggested substantial contributions of organic matter from grasses to the soil organic matter pool. However, with increased depth, C3 carbon inputs became more prominent, indicating the influence of forest vegetation that existed prior to the implementation of agricultural managements. DOM concentrations decreased with soil depth due to reduced carbon inputs, sorption to minerals, or oxidation. DOM composition did not show significant changes among different land use and managements. Lignin was identified as the primary contributor to oxidized DOM with increasing soil depth. The composition of DOM exhibited a shift from more aromatic and higher molecular weight compounds in topsoil layers to smaller, more aliphatic compounds in subsoil layers. Our key findings revealed that aliphatic compounds, particularly fatty acids, tend to accumulate in deeper soil layers. This phenomenon was consistent in pastures dominated by grasses but not in soils near treed vegetation. Overseeding (from C3 plants) did not significantly impact DOM compositions, emphasizing the persistence of C4 plants in these systems. The presence of inorganic elements in soil water extracts showed minimal impact on DOM dynamics, suggesting decoupled organic and inorganic biogeochemical cycles in tropical pasturelands.

Chemical characterization and sources of background aerosols in the eastern Mediterranean

Measurements of the composition of the gas and particulate phases were conducted from May 9 to June 4 of 2016 at the Finokalia (Greece) remote coastal site in the eastern Mediterranean, continuing the effort to track long term changes of the atmospheric chemical composition in the area. Finokalia is influenced by air masses arriving in the site from regional sources in Europe, Africa, and other locations. In this study, a series of instruments and analysis techniques were used for the first time at the Finokalia site to characterize the composition of the organic aerosol (OA). The PM1 was composed of ammonium sulfate/bisulfate (60%), followed by organics (35%) and black carbon (BC) (4%). The OA was highly oxidized with an average oxygen-to-carbon (O:C) ratio of 0.81. Source apportionment of high-resolution organic aerosol mass spectra via positive matrix factorization (PMF) identified four factors: less oxidized oxygenated organic aerosol (LO-OOA), more oxidized oxygenated organic aerosol (MO-OOA), marine-related oxygenated organic aerosol (marine-OOA) and hydrocarbon-like organic aerosol (HOA). The LO-OOA (O:C = 0.92) was the dominant factor for most of the campaign (51% of the PM1 OA), while the MO-OOA (O:C = 1.1) was responsible for 11% of the OA. The marine-OOA factor was also highly oxidized (O:C = 1.03), contributing on average 24% to the total OA and was found to be well correlated with sulfate (R2 = 0.83). The anthropogenic HOA factor (O:C = 0.36) was related to activities in the island of Crete. Its mass spectrum was quite similar (R2 = 0.86–0.95) to those of other HOA factors in the literature and its average concentration was 0.2 μg m−3 (14% of OA). High molecular weight compounds were found, suggesting the presence of oligomers in agreement with the presence of a highly oxidized quenching agent. Aromatic VOCs, like benzene, toluene, and xylenes were on average 0.17, 0.66 and 0.36 ppb, respectively with toluene concentrations indicating the presence of a local source despite the remote nature of the site. New particle formation (NPF) was observed during 26% of the days. The air masses during NPF events passed over the island of Crete and the Balkans and were characterized by a low condensation sink (5.9 ± 2.2 10−3 s−1). Nucleation mode particle concentrations during NPF days had an additional evening peak between 17:00 and 22:00, which was accompanied by an HOA peak implying the influence of a source of sub-25 nm particles in the extended area. These findings show that even a relatively remote site like Finokalia is occasionally affected by sources located tens of kilometers away, something that should be taken into account in the interpretation of past and future measurements in this location.

Effects of granule disintegration and sludge re-aggregation on fouling behaviors and bio-cake formation in aerobic granular sludge membrane bioreactor (AGMBR)

The contribution of granules to membrane fouling alleviation in aerobic granular sludge-membrane bioreactor (AGMBR) has been increasingly investigated, yet the inoculated granules in MBR are more unstable than those in conventional AGS system and thus in-depth insight into the effects of the mutual transformation between granules and flocs on membrane fouling as well as corresponding bio-cake formation is necessary. Herein, we found that the disintegration of granules was accompanied by the release of soluble microbial products (SMP) and the increase of microbial diversity. The re-granulation phase occurred when granules gradually re-dominated the sludge system with the growth of biomass and the massive secretion of extracellular polymeric substances (EPS), corresponding to the declined microbial diversity and stable pollutants removal (COD: 93.45–98 %, TN: 21.06–36.86 %). Compared with the granule disintegration phase, less flocs deposition and fewer contents of SMP containing high molecular weight (>100 kDa) compounds in bio-cakes in the re-granulation phase resulted in the longer filtration period, as evidenced by lower attractive interaction energies between sludge foulants and membranes according to extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. Microbial community analysis demonstrated higher relative abundance of filamentous bacteria (Thiothrix) and lower relative abundance of denitrifiers (e.g, Hydrogenophag, Trichococcus, Arenimonas, Acinetobacter) in bio-cakes in the re-granulation phase. Besides, the genera Thiothrix, norank_f__env.OPS_17 and Aeromonas may be responsible for the organic foulants accumulation on membrane surface. More importantly, stronger positive correlations among microbial populations between bio-cake and suspended sludge in the re-granulation phase indicated the lower propensity of membrane fouling. The systematic insights into the effects of granules disintegration and sludge re-aggregation on fouling layer may have important implications for the future development of membrane fouling control in AGMBR system.

A novel process for recovery and exploitation of polyesters and polyamides from waste polymeric artifacts

Plastic waste is one of the world's biggest sources of pollution. Despite the growing trend towards recycling, there are currently no effective technologies to offset the continuous increase in plastic production. Polyesters and polyamides are among the most widely produced single-use plastics, mainly used in the manufacture of textiles and soft drink bottles. Currently, only a small proportion of these polymers can be effectively recycled. The two primary methods employed for this purpose are mechanical and chemical recycling. Presently, mechanical recycling remains the more widely adopted process within the industrial sector. However, the treatment process is limited to a narrow range of waste materials as it is impossible to remove dyes and the mechanical properties deteriorate due to incompatibility between different plastic materials. Another critical limit of this recycling technology is the limited number of recycling loops that can be done due to the thermal degradation that occurs during the extrusion process. The alternative option is chemical recycling, which allows the depolymerization of the original product to recover the monomers directly. The main drawbacks are the long reaction times and the many solvents needed to achieve high-purity products. As a results, chemical recycling is only economically feasible for large companies that can produce the virgin polymer in situ. In this work, a new technology has been patented. This process consists of three main steps. The first one is the distillation-assisted cyclodepolymerization (DA-CDP), introduced as a modification of the CDP process. In this unit, cyclic oligomers together with high molecular weight compounds are produced. Then, after polymer purification, it is possible to achieve the same molecular weight as the initial polymer in less than 30 min, exploiting the ring-opening polymerization (ROP) of the next step.

Fate, behaviour and microbial response of diluted bitumen and conventional crude spills in a simulated warm freshwater environment

Diluted bitumen (DB), one of the most transported unconventional crude oils in Canada's pipelines, raises public concerns due to its potential spillage into freshwater environments. This study aimed to compare the fate and behaviour of DB versus conventional crude (CC) in a simulated warm freshwater environment. An equivalent of 10 L of either DB or CC was spilled into 1200 L of North Saskatchewan River (NSR) water containing natural NSR sediment (2.4 kg) in a mesoscale spill tank and its fate and behaviour at air/water temperatures of 18 °C/24 °C were monitored for 56 days. Oil mass distribution analysis showed that 42.3 wt % of CC and 63.6 wt% of DB resided in the oil slicks at the end of 56-day tests, consisting mainly high molecular weight (HMW) compounds (i.e., resins and asphaltenes). The lost oil contained mainly low molecular weight (LMW) compounds (i.e., light saturates and some aromatics) into the atmosphere, water column, and sediment through collective weathering processes. Notably, weathered CC emulsified with water and remained floating until the end, while the weathered DB mat started to lose its buoyancy after 24 days under quiescent conditions and resurfaced once waves were applied. Analysis of the microbial communities of water pre- and post-spills revealed the replacement of indigenous microbial communities with hydrocarbon-degrading species. Exposure to CC reduced the microbial diversity by 12%, while exposure to DB increased the diversity by 10%. During the early stages of the spill (up to Day 21), most dominant species were positively correlated with the benzene, toluene, ethylbenzene, and xylenes (BTEX) content or polycyclic aromatic hydrocarbon (PAH) content of the water column, while the dominant species at the later stages (Days 21–56) of the spill were negatively correlated with BTEX or PAH content and positively correlated with the total organic carbon (TOC) content in waters.

Determining the sources and distribution of polycyclic aromatic hydrocarbons in the soil of different oil fields at Basrah governorate, Iraq

The object of the research is polycyclic aromatic hydrocarbons (PAHs). For the purpose of determining the source and distribution of PAHs, soil samples from the 11 oil fields in the Basrah governorate (Seba, Safwan, Majnoon, Ratawi, Bergezia, Qurna1, Qurna2, Shuaaba, South and North Rumaila, and al Zubair) were taken at a depth of 0 to 20 cm. According to their molecular weight, they were separated into two main groupings. The first group of compounds consisted of six compounds: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, and anthracene. These light (low molecular weight) compounds have two to three fused aromatic rings. The first group includes nine chemicals: floranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b), benzo(k), benzo(a), benzo(a), indeno(1,2,3,c,d), and benzo(g,h,i)perylene. These heavy (high molecular weight) compounds included four or more fused aromatic rings. The PAHs compounds ranged in value from the lowest (0.16 ng/g dry weight of benzo(a)anthracene at station West Quarna1) to the highest (680 ng/g dry weight of benzo(g,h,i)perylene that emerged at station North Rumail). The total concentration of PAHs ranged from 77.67 ng/g in South Rumaila Field while highest concentration is 2284.27 ng/g in North Rumail. The PAHs compound has low and high molecular weight, their ratio of LMW/HMW (low molecular weight/high molecular weight) and phenanthrene/anthracene, fluoranthene/pyrene indicated that the source of PAHs was pyrogenic only. The PAH diagnostic ratios and principal component analysis (PCA) indicated that PAHs in soils essentially originated from emissions and combustion. This study gave a baseline on the source and distribution of these compounds in oil fields at Basrah governorate and can be used as a baseline for coming study in the future.

COMPARATIVE STUDY OF PHYSIC-CHEMICAL PROPERTIES OF POLYSACCHARIDES SELECTED FROM PRUNELLA SPP.

Natural high molecular weight compounds are used in medicine separately and in complex drugs as concomitant substance and as transport substances for the main compounds. Polysaccharides are plant polymers and its physic-chemical properties are useful in the development of pharmaceutical substances of plant origin. The aim of this study is investigation of physic-chemical properties of polysaccharides selected from Prunella spp. herb. For this aim, we solved the following tasks: estimate medium molecular weight of water-soluble polysaccharides (WSPS) and pectinic substances (PS) by viscosimeter, isoelectric point, distribution coefficient, superficial activity. Results. WSPS and PS from P. laciniata herb has the largest molecular weight (30493 g/mol and 25607 g/mol respectively). Macromolecules of WSPS and PS are electroneutral in the solution with pH&lt;7. The molecules do not affect the surface tension at the boundary of the two phases, but at the same time they have a penetrating ability. Conclusions. Polysaccharides from Prunella spp. Have a high molecular weight more 10 k g/mol and this property may cause the elasticity of the dosage form. Macromolecules are electroneutral in the acidic environment and insoluble in water solution and have small ability to swell. Polymers have high penetrating ability through the cell membrane. These properties determine transport and bioavailability of polysaccharides and main compounds.

Unravelling molecular fractionation of dissolved organic matter on ferrihydrite-phosphate complexes

Association of dissolved organic matter (DOM) with iron (Fe) oxyhydroxides leading to significant molecular fractionation, plays a significant role in biogeochemical cycling of carbon in soils. However, the molecular effects of coexisting phosphate, a widely distributed oxyanion in agricultural soils that has a strong affinity with Fe oxyhydroxides on such a process remain poorly understood. Here, using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) with a superiority in deciphering DOM characteristics at the molecular level, this study reveals the DOM molecular fractionation characteristics on ferrihydrite-phosphate (Fh-P) complexes. Results show that the adsorption of DOM on Fh-P complexes can be significantly inhibited by ∼50% compared to that on ferrihydrite. Optical spectroscopy and FT-ICR-MS further indicate that phosphate can greatly change the molecular fractionation of DOM on Fh-P complexes. Phosphate preferentially inhibits the highly aromatic, hydrophobic, and high molecular weight compounds (> 400 Da) of DOM on Fh-P complexes, such as condensed hydrocarbon and tannin; more CHONS compounds preferentially adsorb on the Fh-P complexes than thoseon ferrihydrite. Phosphate inhibits the adsorption of DOM with the characteristics of high oxygen atoms number, aromaticity index (AI), and double bond equivalents (DBE) on ferrihydrite. Our study demonstrates that the inhibitory effects of phosphate on the adsorption of the DOM can significantly influence the fractionation and adsorption of DOM by ferrihydrite. The findings of this work deepen our understanding of biogeochemical cycling of DOM in soil and aquifer environments.

Harnessing root exudates for plant microbiome engineering and stress resistance in plants

A wide range of abiotic and biotic stresses adversely affect plant's growth and production. Under stress, one of the main responses of plants is the modulation of exudates excreted in the rhizosphere, which consequently leads to alterations in the resident microbiota. Thus, the exudates discharged into the rhizospheric environment play a preponderant role in the association and formation of plant-microbe interactions. In this review, we aimed to provide a synthesis of the latest and most pertinent literature on the diverse biochemical and structural compositions of plant root exudates. Also, this work investigates into their multifaceted role in microbial nutrition and intricate signaling processes within the rhizosphere, which includes quorum-sensing molecules. Specifically, it explores the contributions of low molecular weight compounds, such as carbohydrates, phenolics, organic acids, amino acids, and secondary metabolites, as well as the significance of high molecular weight compounds, including proteins and polysaccharides. It also discusses the state-of-the-art omics strategies that unveil the vital role of root exudates in plant-microbiome interactions, including defense against pathogens like nematodes and fungi. We propose multiple challenges and perspectives, including exploiting plant root exudates for host-mediated microbiome engineering. In this discourse, root exudates and their derived interactions with the rhizospheric microbiota should receive greater attention due to their positive influence on plant health and stress mitigation.

Contrasting optical properties of dissolved organic matter between oceanic regions near the Getz and Dotson ice shelves in the Amundsen Sea, West Antarctica

The Amundsen Sea, located in West Antarctica, is experiencing rapid melting due to the intrusion of Circumpolar Deep Water, which is causing ice sheet thinning and basal melting. The resulting changes can affect the biogeochemical cycle of dissolved organic matter (DOM) by supplying iron from sea ice and/or glacier, thereby influencing primary production and ocean circulation. Therefore, it is crucial to understand the dynamics of the DOM in this region. In this study, our primary focus was to examine the optical properties of DOM in the oceanic regions adjacent to the West Getz Ice Shelf (WGIS) and the Dotson Ice Shelf (DIS). Significant differences in DOM optical properties, including the chromophoric DOM (CDOM) absorption coefficient at 350 nm (a350), spectral slope coefficient (S275–295), and specific UV absorbance at 254 nm (SUVA254), were observed between the WGIS and DIS regions (t-test, p < 0.05). Notably, the WGIS regions exhibited high a350 values. Additionally, the S275–295 and SUVA254 values, which serve as indices of molecular weight, indicated that the DOM pool in the WGIS regions was dominated by high molecular weight compounds with a substantial proportion of aromatic compounds. In contrast, the low values of a350 and SUVA254 along with the high S275–295 values in the DIS region suggested the dominance of low molecular weight CDOM associated with compounds of lower aromaticity. Furthermore, significant negative correlations were found between biomass of Phaeocystis antarctica (P. antarctica) and phosphate (PO4) in the WGIS regions (r2 = 0.82, p < 0.01 for WGIS 1 and r2 = 0.73, p < 0.01 for WGIS 2). However, no significant relationship was observed in the DIS region. These findings suggest that the high value and molecular weight of a350, extending from the surface layer to the deep layer, in the WGIS regions were associated with autochthonous sources, primarily driven by the colony-forming bloom of P. antarctica. These findings demonstrate that the quantity and quality of DOM in the Amundsen Sea are strongly affected by bloom conditions. The results emphasize that a combination of physical and biological processes interacts in complex ways to determine the characteristics of DOM in the Amundsen Sea.