High Molecular Weight Research Articles

Characterization, source profiles and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in urban dust of 14 Chinese cities

ABSTRACT Data for 16 USEPA priority PAHs were collected in urban dust from 14 cities in China between 2008 and 2022, and concentration, profile composition, and human health risk were investigated. The mean concentration of PAHs was 6.60 mg kg−1, ranging from 2.88 mg kg−1 to 13.88 mg kg−1, and it was higher than other important cities in neighboring countries of China. Among different individual PAHs, mean fluoranthene (Flr) was dominant, accounting for 15.04%, and low molecular weight PAH (LMW) was almost a third of high molecular weight PAH (HMW). The results of PAH composition profiles suggested that the proportion of different rings of PAHs increased in order: 2-ring PAHs (4.40%)< 6-ring PAHs (15.73%)< 3-ring PAHs (17.77%)< 5-ring PAHs (22.54%)< 4-ring PAHs (39.56%). The results of the source appointment suggested that pyrogenic sources and mixed sources, particularly wood, grass, coal, and diesel combustion, were the main sources of PAHs in urban dust. The results of the health risk assessment illustrated that children were more vulnerable to PAHs, and ingestion was the dominant exposure pathway to PAHs (78.152%, 67.519%, 73.206%, and 72.957% of children, adolescents, adults, and the total lifetime cancer risk (TLCR)). PAH pollution in urban dust from different cities in China was a commonly existing phenomenon, but the mean and maximum of TLCR were acceptable according to the standard established by USEPA (10−4). Based on Monte Carlo simulations, body weight (BW) was the most important uncertain input in three age groups (60.75%-91.22% contribution).

Mannose/stearyl chloride doubly functionalized polyethylenimine as a nucleic acid vaccine carrier to promote macrophage uptake

Transmembrane transport remains a significant challenge for nucleic acid vaccine vectors. Promoting the ability of immune cells, such as macrophages, to capture foreign stimuli is also an effective approach to improving cross-presentation. In addition, polyethyleneimine (PEI) has gained attention in the field of nucleic acid vaccine carriers due to its excellent gene transfection efficiency and unique proton buffering effect. However, although high molecular weight PEI exhibits high efficiency, its high-density positive charges make it highly toxic, which limits its application. In this study, mannose/stearyl chloride functionalized polyethylenimine (SA-Man-PEI) was prepared by functionalizing PEI (molecular weight of 25 kDa) with mannose with immunomodulatory and phagocyte targeting effects, and an alkyl hydrophobic chain segment, which could easily promote cell uptake. Moreover, the functionalized-PEI retains a strong proton buffering effect, which helps the carrier escape from the lysosome. The particle sizes of the composite particles formed by SA-Man-PEI and ovalbumin (OVA) were below 200 nm, with good storage stability at both 4 °C and 37 °C. At a drug concentration of 2 μg/mL, the cell survival rate of functionalized-PEI was 19.2% higher than that of unfunctionalized PEI. In vitro macrophage endocytosis experiments showed that SA-Man-PEI could significantly enhance the macrophage uptake of composite particles, compared to unfunctionalized PEI or single-functionalized PEI. This study offers a new approach for developing PEI as a nucleic acid vaccine carrier, which could simultaneously enhance cell targeting and promote cell uptake.

RNA Blotting by Electrotransfer and RNA Detection.

Northern blot, or RNA blot, is a widely used technique in molecular biology to detect and semi-quantify specific RNAs. The advantage of this method is its ability to simultaneously estimate the sizes and quantities of degraded or processed RNA products. Northern blotting involves the use of electrophoresis to separate RNA samples by size. These RNAs are then transferred and immobilized on a membrane, and the RNAs of interest are detected by hybridization using a sequence-specific labeled DNA probe. Agarose gels are typically used in routine procedures to allow for the separation and specific detection of high molecular weights (ranging from tRNA size to several kb RNAs). However, acrylamide gels are preferred when the separation of lower weight RNAs (ranging from 20 to 200 nucleotides) is required. Both approaches for RNA separation are presented here. The term "northern blot" originally referred to the capillary transfer of RNA from the electrophoresis gel to the blotting membrane. However, RNA transfer to the membrane by electrotransfer has also been proven to be a suitable and fast method for transferring RNAs from acrylamide and agarose gels to the membrane.

Ultra-high molecular weight polyethylene filled with iron by mechanical alloying

The ultra high molecular weight polyethylene (UHMWPE) shows properties that provide wide industrial and technological interest. To study the influence of iron particles on UHMWPE, the polymer was filled with Fe-powder in different stoichiometries through mechanical alloying (MA). The MA resultant samples were subjected to various analyses aiming at the characterization of mechanical, structural, and hyperfine properties. The tensile test indicated a small change in the stress-strain curves, this change was related to the yield stress. The X-ray diffraction showed the presence of a monoclinic phase, a metastable phase induced by deformation. Mössbauer spectroscopy pointed at the presence of three iron sites: metallic iron, Fe2+ e Fe3+. Considering these results, it is possible to ascertain that the iron weakly changes some properties of the polymer without degradation. There is a clear indication that iron atoms interact with carbon atoms, between the polymer chains, creating cross-links.

Comparative evaluation of commercial DNA isolation approaches for nanopore-only bacterial genome assembly and plasmid recovery.

The advent of Oxford Nanopore Technologies has undergone significant improvements in terms of sequencing costs, accuracy, and sequencing read lengths, making it a cost-effective, and readily accessible approach for analyzing microbial genomes. A major challenge for bacterial whole genome sequencing by Nanopore technology is the requirement for a higher quality and quantity of high molecular weight DNA compared to short-read sequencing platforms. In this study, using eight pathogenic bacteria, we evaluated the quality, quantity, and fragmented size distribution of extracted DNA obtained from three different commercial DNA extraction kits, and one automated robotic platform. Our results demonstrated significant variation in DNA yield and purity among the extraction kits. The ZymoBIOMICS DNA Miniprep Kit (ZM) provided a higher purity of DNA compared to other kit-based extractions. All kit-based DNA extractions were successfully performed on all twenty-four samples using a single MinION flow cell, with the Nanobind CBB Big DNA kit (NB) yielding the longest raw reads. The Fire Monkey HMW-DNA Extraction Kit (FM) and the automated Roche MagNaPure 96 platform (RO) outperformed in genome assembly, particularly in gram-negative bacteria. Based on our finding, we recommend a minimum read coverage and raw read N50, obtained from the appropriate DNA extraction kit for each bacterial species, to optimize genome assembly and plasmid recovery. This approach will assist end-users in selecting the most effective kit-based extraction method for bacterial whole-genome assembly using only long-read nanopore sequences.

Advances in environmental analysis of high molecular weight disinfection byproducts.

The disinfection of drinking water, while critical for public health, leads to the formation of disinfection byproducts (DBPs). Toxicological and epidemiological studies have demonstrated that exposure to disinfected water samples may pose adverse effects on human health. Recent research highlights the potential greater toxicity contribution of DBP fractions with high molecular weight (MW) (with more than two carbon atoms) compared to regulated low MW DBPs, emphasizing the need for advanced analytical techniques to identify and characterize these fractions. In this review, we summarize different analytical techniques for indirectly assessing DBP precursors and directly analyzing DBPs, discussing their advantages and limitations. Additionally, since identifying DBP toxicity agents in complex water mixtures is crucial for further optimizing water disinfection and controlling DBP formation, key DBP identification methods based on both chemical and bioassay metrics are also included and discussed. Finally, we highlight three important aspects for the future development of analytical methods to enhance the understanding of high MW DBP formation.

Crystallization, thermal, and compatibility performances of poly (butylene succinate) (PBS)/poly((R)‐3‐hydroxybutyrate‐co‐(R) 3‐hydroxyhexanoate) (PHBHHx) blends

AbstractBiodegradable materials provide protective properties comparable to conventional plastics while diminishing reliance on nonrenewable resources. Environmentally friendly polymer blends were prepared by melting poly(R)‐3‐hydroxybutyrate‐co‐(R)‐3‐hydroxyhexanoate) (PHBHHx) with poly (butylene succinate) (PBS). PBS was synthesized through esterification and polycondensation using 1,4‐butanediol and succinic acid, with tetrabutyltitanate as the catalyst. The PHBHHx is supplied by Bulepha®PHA Company of China, model number BP330. The effects of PHBHHx content on thermal behavior, compatibility, and thermal stability of PBS/PHBHHx blends were systematically investigated. Differential scanning calorimetry (DSC) results indicated that the addition of PHBHHx influenced the crystallization behavior, the crystallization temperature (Tc) of PBS decreased meanwhile, the crystallization half‐time of PBS is reduced to 1.5 min compared with neat PBS (5 min) after isothermal is crystallized at 95°C. Polarized Optical Microscopy (POM) images also revealed that crystallization rate accelerated in the blend with increasing PHBHHx content. Rheological and Scanning Electron Microscopy (SEM) analysis demonstrated that incorporating a significant content of PHBHHx reduced compatibility between PBS and PHBHHx. Mechanical property testing indicates that the addition of PHBHHx reduced the toughness of blends. Additionally, the addition of a small amount of PHBHHx imparts a higher crystallinity (56%) and heat resistance of the PBS/PHBHHx blends (78°C) was higher than neat PBS (74°C).Highlights Laboratory synthesis of high molecular weight PBS. Optimal ratios improved crystallinity and thermal stability of blends. A systematic study of the crystallization properties of blends.

Effect of transglutaminase cross-linking on the structure and emulsification performance of heated black bean protein isolate.

Transglutaminase (TGase) is a heat-resistant biocatalyst with strong catalytic activity, which functions effectively under moderate temperature and pH conditions, and is used widely in protein cross-linking and recombination. Transglutaminase cross-linking is a novel and specific modification method for black bean protein isolate (BBPI). This article investigates the effect of transglutaminase cross-linking on the structure and emulsification performance of heated BBPI. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that heated BBPI with TGase had a higher molecular weight than heated BBPI without TGase, and the protein bands widened with increasing enzyme activity, indicating that TGase cross-linking promoted protein molecule aggregation. A high molecular weight polymer can better stabilize the oil-water interface, preventing the emulsion from layering. Fourier transform infrared (FTIR) spectroscopy showed that the α-helix content decreased from 15.64% to 13.75%, and the β-sheet content increased from 48.13% to 54.08%. The decrease in α-helix content and increase in β-sheet content could make the structure more stable and improve the emulsifying properties of heated BBPI. When TGase was 20 U g-1, the protein emulsification activity index (EAI) reached its highest value of 1.87 m2 g-1, and the emulsification stability index (ESI) value was 0.27 min (P < 0.05); these figures were 0.19 m2 g-1, and 0.07 min higher, respectively, than in the sample without added TGase. In summary, transglutaminase cross-linking has a positive effect on the structure and emulsification performance of heated BBPI and can be used as an effective method for BBPI modification. © 2024 Society of Chemical Industry.

Composition and polymerisation products influence on the viscosity of coal tar wash oil

Wash oil is a fraction obtained by the distillation of coal tar and is primarily used for the absorption of light oil from coke oven gas. During operation, the oil undergoes polymerization and loses some components, necessitating the removal of the used oil and its replacement with fresh wash oil. The rheological properties of the studied oils were determined using a Brookfield DV2T rotational controlled-shear rate rheometer. Gas chromatographic analysis, gas chromatography/mass spectrometry, and IR spectroscopy were employed to evaluate the oil’s characteristics. By adding individual components to the wash oil, it was found that these components could be categorized into three groups: viscosity enhancers, viscosity reducers, and non-polar oil substances with medium molecular weight that have no significant effect on viscosity. The addition of relatively polar components with greater molecular weight and a planar, rigid structure leads to an increase in viscosity. Conversely, the incorporation of naphthalene and its methyl homologues, which have lower molecular weights, reduces viscosity by disrupting intermolecular interactions; their lower heats of crystallization also inhibit the formation of structured order in the liquid, further contributing to the reduction in viscosity. The most substantial increase in oil viscosity was observed with the addition of indene-coumarone resins, attributed to their high molecular weight and polymer structure.

Investigating the effect of fermentation byLactobacillus reuteri on biochemical properties of Ceylon Cinnamon

Abstract Introduction Fermentation is an important biotechnological process that improves the biochemical properties of natural raw materials by transforming high molecular compounds into more beneficial low molecular compounds through microbial biotransformation. Ceylon cinnamon (Cinnamomum zeylanicum Blume), globally recognized as 'true cinnamon', contains high molecular weight, complex compounds that are responsible for its renowned antioxidant, antibacterial, and therapeutic properties, making it a vital component in medicinal applications1. Aims The present study aimed to investigate the effect of fermentation by Lactobacillus reuteri on selected phytochemical contents, antioxidant, and antibacterial properties of bark extracts of Ceylon cinnamon (Cinnamomum zeylanicum Blume) and to determine the optimum conditions for fermentation of Cinnamon bark extract by L. reuteri. Method Authenticated Ceylon cinnamon bark (CCB) was extracted into water using the decoction method. The water extract was fermented by L. reuteri under controlled conditions (pH 6, incubation at 35 ºC) and optimized using two parameters; the inoculum density (1.5×108 cfu/ml and 7.5×108 cfu/ml) and incubation time (2 and 4 days). After fermentation, total polyphenolic content (TPC), total flavonoid content (TFC), DPPH free radical scavenging activity and antibacterial activity of non-fermented extracts (NFE) and fermented extracts (FE) of CCB were evaluated. Antibacterial activity was determined using the agar well diffusion method against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Ethical approval was not required since no human or animal study was done during the study. Results The extract fermented with an inoculum density of 7.5×108 cfu/ml and incubated for 4 days showed the highest TFC (19.3 ± 0.3 mg RE/g) and antioxidant activity (IC50: 97.2 ± 0.8 µg/ml) in comparison to that of NFEs (TFC:13.3 ± 0.3 mg RE/g and DPPH activity: IC50: 233.7 ± 12.8 µg/ml). Moreover, the fermented samples showed a reduction in TPC, indicating possible biotransformation of compounds. and no significant change in the antibacterial activity in comparison to the non-fermented samples. Discussion and Conclusion This study was mainly focused on investigating the effect of fermentation of Ceylon cinnamon bark aqueous extract by Lactobacillus reuteri. The increased antioxidant activity and total flavonoid content are notable and could be attributed to chemical transformations of some complex flavanols including catechin gallate and epicatechin gallate present in aqueous cinnamon to catechin and epicatechin monomers by the action of enzymes secreted by L. reuteri during the fermentation process2. Hence, this study suggests that fermentation using L. reuteri has a considerable positive impact on certain biochemical properties of cinnamon water extract. Cinnamon bark is a complex matrix containing various phytochemicals that could interact with bacterial strains in ways that are not fully understood. These interactions could lead to unexpected effects or limitations during fermentation.

Fast Dissolution of Chitin in Amino Acids Based Deep Eutectic Solvents Under the Assistance of Microwave.

Due to the abundant hydrogen bond networks, high crystallinity, and high molecular weight of chitin, it is difficult to dissolve chitin in most solvents. Meanwhile, most of the existing solvent systems have the disadvantages of high toxicity, low solubility, and high cost. Therefore, the efficient and rapid dissolution of chitin using green solvents is urgently needed. In this work, ternary DES with amino acids, urea, and 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) is prepared at first. Then chitin can be dissolved fastly with the assistance of a microwave. Compared with the conventional heating process (110°C, 6-8h), the microwave process can be shortened to only 3-10min. The successful dissolution of chitin is verified by means of fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), rheology studies, and optical light microscope, and the dissolution mechanism contributed to the synergistic destroying of the hydrogen bond networks of chitin by amino acids and DBU. The DES solvent can be well recovered with the remaining of its dissolving ability to chitin.

Viscoelastic High-Molecular-Weight Hyaluronic Acid Hydrogels Support Rapid Glioblastoma Cell Invasion with Leader-Follower Dynamics.

Hyaluronic acid (HA), the primary component of brain extracellular matrix, is increasingly used to model neuropathological processes, including glioblastoma (GBM) tumor invasion. While elastic hydrogels based on crosslinked low-molecular-weight (LMW) HA are widely exploited for this purpose and have proven valuable for discovery and screening, brain tissue is both viscoelastic and rich in high-MW (HMW) HA, and it remains unclear how these differences influence invasion. To address this question, hydrogels comprised of either HMW (1.5 MDa) or LMW (60 kDa) HA are introduced, characterized, and applied in GBM invasion studies. Unlike LMW HA hydrogels, HMW HA hydrogels relax stresses quickly, to a similar extent as brain tissue, and to a greater extent than many conventional HA-based scaffolds. GBM cells implanted within HMW HA hydrogels invade much more rapidly than in their LMW HA counterparts and exhibit distinct leader-follower dynamics. Leader cells adopt dendritic morphologies similar to invasive GBM cells observed in vivo. Transcriptomic, pharmacologic, and imaging studies suggest that leader cells exploit hyaluronidase, an enzyme strongly enriched in human GBMs, to prime a path for followers. This study offers new insight into how HA viscoelastic properties drive invasion and argues for the use of highly stress-relaxing materials to model GBM.

Tuning the antioxidant and antibacterial properties of lignin by physicochemical modification during sequential acid precipitation from Kraft black liquor

Turning lignin from black liquor waste into value-added bioactive agents is one of the possible routes for improving the sustainability and profitability of lignocellulosic industry. However, due to chemical and structural variability of lignin, it is necessary to isolate specific lignin fractions from black liquor with the purpose to achieve samples with unique chemical and structural characteristics and therefore, specific biological activities. In this study, poplar lignin fractions isolated from Kraft black liquor by sequential acid precipitation at pH´s 7.5, 5 and 2.5 (denoted as P-7.5, P-5 and P-2.5) were characterized according to their physicochemical, antioxidant and antibacterial properties. In general, lignin fractions displayed a wide elimination of lateral chains (aryl-β ether and C–C) and, therefore a high phenolic content and low molecular weight, as the pH sequential precipitation was decreased from 7.5 to 2.5. Moreover, thermal analysis revealed that the P-7.5 lignin fraction showed higher thermal stability than P-2.5 and P-5. In terms of antioxidant activity, the P-7.5 lignin fraction, with a higher S/G ratio and a less oxidized structure compared to P-5 and P-2.5, exhibited higher antioxidant activity. In addition, lower antibacterial effect was observed for all lignin fractions against Escherichia coli compared to that obtained against Staphylococcus aureus. Among them, the P-2.5 and P-5 fractions, with higher phenolic content and lower molecular weight values than P-7.5, showed a greater antibacterial effect against S. aureus.

Alkyl initiated ring opening polymerization of lactide by indium complexes supported by NCN pincer ligands.

Indium-alkyl NCN pincer complexes supported by amine and imine donors are active catalysts for the ring opening polymerization of lactide. The amine indium complexes are significantly more active for polymerization due to the decoordination of the amine donors at higher temperatures. Solid state structures of the imine and amine indium complexes indicate that the imine-indium bonds are stronger than the analogous amine-indium bonds. Higher molecular weight polymers that were not observable by MALDI-TOF were shown to be linear by comparing their intrinsic viscocities with those of known linear polymers. The alkyl indium complexes are more active than the analogous alkyl aluminum complexes but are prone to transesterification reactions.

Peroxydisulfate Activation by Biochar from Banana Peel Promoted with Copper Phosphide for Bisphenol S Degradation in Aqueous Media

In this work, the decomposition of bisphenol S (BPS) by biochar derived from banana peel (BPB) promoted by copper phosphide (Cu3P) was examined. Different materials with Cu3P loadings from 0.25 to 4.00 wt.% on biochar were synthesized, characterized using the Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD) and a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS), and evaluated. Nearly all of the synthesized materials exhibited low to moderate adsorption capacity, attributable to their limited surface area (&lt;3.1 m2/g). However, in the presence of sodium persulfate (SPS), the 2%Cu3P/ΒPB/SPS system was capable of removing 90% of 500 μg/L BPS in less than 10 min. The system’s performance was enhanced under inherent pH, and the reaction rate followed pseudo-first-order kinetics with respect to BPS and persulfate concentrations. Interestingly, the presence of 250 mg/L of sodium chloride had a negligible effect, while low to moderate inhibition was observed in the presence of bicarbonates and humic acid. In contrast, significant retardation was observed in experiments performed in real matrices, such as secondary effluent (WW) and bottled water (BW). According to scavenging experiments, both radical and non-radical mechanisms participated in the BPS degradation. Four transformation products were identified using the UHPLC/TOF-MS system in negative ionization mode, with two of them having higher molecular weights than BPS, while the other two TBPs involved the ring-opening reaction, and a BPS decomposition pathway was proposed.

Non-Covalent Interactions of Lotus Root Polysaccharides and Polyphenols and their Regulatory Mechanism on Macrophage Functions

Despite the interaction between polyphenols and polysaccharides in food products, their specific non-covalent interactions and effects on macrophage functions are not well understood. Therefore, the interaction and mechanism of purified lotus root polysaccharide (PLRP) with polyphenols, and the regulatory mechanisms of the PLRP-polyphenol complex on the macrophage functionals were studied. By combining ferulic acid (FA) and chlorogenic acid (CHA) with PLRP, the complexes PLRP-FA, PLRP-CHA and the physical mixtures PLRP&amp;FA and PLRP&amp;CHA were prepared, where their mass ratios of polyphenols to PLRP were 143.97 and 601.67 mg g−1. Nuclear magnetic resonance (NMR), Fourier-transform infrared (FTIR), Ultraviolet (UV), and Transmission electron microscopy (TEM) analyses confirmed that PLRP and polyphenols may engage in non-covalent interactions via hydrogen bonds and hydrophobic interactions. We confirmed that non-covalent interactions led to high molecular weight, dense complexes. Both PLRP and its polyphenol complexes stimulated NO production by macrophages to varying degrees without exacerbating lipopolysaccharide-induced inflammatory responses. PLRP and PLRP-polyphenol complexes repaired cells with impaired antioxidant capacity, depending on doses. Those results indicated that after the combination of lotus root polysaccharide and polyphenol, the molecular weight and conformation changed significantly, which influenced the biological activity. RNA-seq analysis suggested that the regulatory mechanism of PLRP-polyphenol complex in macrophages may mainly involve oxidative phosphorylation, FoxO, TNF, IL-17, MAPK, NF-kappa B, and other signaling pathways. This study investigated the effects of polyphenol binding on the physicochemical characteristics and functional activities of polysaccharides, which provided references for the development of polysaccharide functional products and the control of nutritional quality.

Methyl jasmonate improves rubber production and quality in Lactuca Serriola.

The increase in demand for natural rubber has led to the search for alternative sources. Lactuca serriola is emerging as a promising candidate, as the quality of the natural rubber it produces is comparable to that of the Pará Rubber Plant, Hevea brasiliensis. This study examines the effect of methyl jasmonate (MeJA), a known elicitor, on the expression of key rubber biosynthesis pathway genes (HMGR1, HMGS1, CPT2, and SRPP1) in the latex of L. serriola plants. The expression levels of these genes increased significantly after the foliar application of 200 and 400 µM MeJA. The highest relative expression level for HMGR1, HMGS1, CPT2 and SRPP1 was 3.74, 18.56, 11.91and 16.59 fold respectively. Furthermore, the rubber content in L. serriola showed a significant rise post-treatment compared to the control with increasing the level of MeJA (6.19%, 7.24% and 7.85% which correspond to 0, 200 and 400 µM). Gel permeation chromatography revealed an augmentation in the molecular weight of extracted natural rubber from treated plants. Samples treated with 400 µM of MeJA had the highest molecular weight (1570 kg mol-1) compared to control (1186 kg mol-1). This study has demonstrated that MeJA, through the regulation of rubber biosynthesis genes, is capable of enhancing the quality and quantity of natural rubber extracted from alternative sources, such as L. serriola.

Intrinsic Chemical Drivers of Organic Aerosol Volatility: From Experimental Insights to Model Predictions

AbstractAccurately predicting the volatilities of molecules in aerosols is challenging but crucial for understanding the atmospheric effects of aerosols. We used negative and positive ion electrospray ionization Fourier‐transform ion cyclotron resonance mass spectrometry (FT‐ICR MS) to identify differences in the molecular compositions of gas and particle phase samples from urban atmosphere. We aimed to identify intrinsic chemical parameters that determine and predict the organic aerosol volatility. We found higher average molecular weights, carbon mass percentages, and double bond equivalents (DBE) but lower average O/C ratios and oxygen mass percentages in the particle phase than the gas phase. We identified DBE, which display a significant negative correlation with volatility, as a key parameter. We proposed to improve the previous model for predicting organic aerosol volatility by incorporating DBE as a new variant; and the result showed that this subsequently improved the accuracy of the model, particularly for compounds with minimal or no heteroatoms (0–2) such as hydrocarbons (CH). The revised model offers insights into the contributions of DBE, carbon, nitrogen, oxygen, and sulfur atoms to the volatilities of diverse organic molecules in aerosols and could be applied to improve our understanding of the phase distributions of volatile organic compounds in the ambient air.

Varying the Core Topology in All-Glycidol Hyperbranched Polyglycerols: Synthesis and Physical Characterization.

In the present study, low molecular weight cyclic polyglycidol is used as a macroinitiator for hypergrafting glycidol and producing cyclic graft hyperbranched polyglycerol (cPG-g-hbPG) in the molecular weight range of 103-106gmol-1. Linear graft hyperbranched polyglycerol (linPG-g-hbPG) and hyperbranched polyglycerol (hbPG) are prepared as reference samples. This creates a family of hbPG structures with cyclic, linear, and star cores, allowing to evaluate their properties in solution and in bulk. The morphology study of the high molecular weight structures using atomic force microscopy revealed a spherical shape for cPG-g-hbPG and hbPG, and a cylindrical shape for linPG-g-hbPG in the nanometric range. Small angle X-ray scattering confirmed the compact particle-like structure of this family of hbPG architectures. Interestingly, the glass transition temperature showed a structure dependence, with cPG-g-hbPG having the highest values and hbPG having the lowest values for the same molecular weight. This study is a step forward in the generation of water-soluble polymers with tailored structure and functionality for advanced applications.

Exploration of graphitic carbon from crude oil vacuum residue

Preparation of graphitic carbon from low value refinery waste has captivated immense interest in past years owing to its low cost and abundant nature. Successful utilization of petroleum vacuum residue is a major challenge in the petroleum industry. In this study pyrolysis of vacuum residue fractions has been carried out for the preparation of graphitic carbon like material. The vacuum residue fractions were obtained from three different crude oils originated from Middle East, Canada and South America. The purity of the Aromatic, Resin and Asphaltene (ARA) fractions were confirmed using TLC-FID which denoted complete separation. The chemical composition were determined using elemental analysis and it revealed ARA fractions to be carbon rich regardless of its origin. Further, sulphur content was found to be high in ARA fractions from Heavy Crude oil (HCO). The degree of polymerization and molecular weight measured using GPC specify that asphaltene has high accumulation with high molecular weight compared with aromatic and resins. ARA derived carbon and heat-treated materials were analysed by TGA, XRD and Raman spectroscopy to study microstructural changes in formation of graphite like material. Thermogravimetric analysis of all ARA samples revealed the different decomposition stages for pyrolyzed, calcined and graphitized samples. The results of XRD demonstrated that the distance between the planes (d-spacing) is above 3.35 Å for all high temperature treated ARA derived carbon materials irrespective of its origin, indicating formation of graphite like structure. In Raman analysis, the nature and intensity of G and D bands evolution during each step of pyrolysis is supporting XRD results for formation of highly ordered graphitic carbon material. Furthermore, understanding feed quality has direct influence on high efficiency, low costs and sustainability, the major issues for oil refinery business.