Short-chain Hydrocarbons Research Articles

Exploration on performance of the oxidized collector in the low-rank coal flotation

ABSTRACT Low-rank coal can be concentrated by flotation process using oxidized kerosene, which can improve flotation performance. However, the difference between oxidized kerosene and conventional collector with the same dosage on flotation performance is little known. In this study, the FTIR spectrum, GC-MS analysis and surfaces tension of collectors were analyzed for comparison the physical and chemical properties. The results showed the kerosene appearance of the short hydrocarbon chains with oxygen groups. The surface tension of kerosene is reduced by 21.99 mm/m after oxidation process. The contact angle and flotation tests were used for the kerosene, mixture including oxidized kerosene and kerosene with a mass ratio of 1:1, as well as oxidized kerosene for evaluating the performance. The results showed that the order of coal surface contact angle is that kerosene > mixture > oxidized kerosene. In addition, flotation tests revealed that mixture had superior flotation performance compared with kerosene and oxidized kerosene. The oxidized kerosene could significantly diminish the ash content of flotation concentrates, and the combustible matter recovery of clean coal with mixture is nearly 16.50% higher than that with kerosene. These results constitute a substantial step forward in technical development for resource recycling of low-rank coal.

Performance analysis of a pilot gasification system of biomass with stepwise intake of air-steam considering waste heat utilization

Although the fixed-bed gasifier is widely used because of their simple structure, easy operation, and strong adaptability to biomass type, its economy is weakened by their low bioenergy conversion ability and heat utilization efficiency. Therefore, a novel biomass gasifier with stepwise intake of air–steam is proposed, which also innovatively integrates the concept of multi-stage utilization of waste heat generated during the gasification process into its design. And a pilot system comprising the novel biomass gasifier with a biomass consumption of 30 kg/h has been built. A series of continuous air-steam gasification experiments on pine wood particles shown that, the high-temperature steam in the reduction zone enhanced the ring opening of aromatic hydrocarbons, decarboxylation, dehydroxylation, and the conversion of long-chain to short-chain hydrocarbons, thus increasing the yield of small-molecule gases. The steam reforming reaction played an active role in increasing the hydrogen content, the gasification gas's production and low calorific value. And the relationship among the reaction rates on the surface of char should be VC + H2O＞VC+2H2O＞VC + CO2＞VC+2H2. The minimum input temperature of steam was 350 °C, otherwise more char would be consumed in the oxidation zone to provide heat. The proposed steam-air gasification system achieved optimal performance with an air-to-steam mass ratio (A/S) of approximately 8, a steam temperature of 400 °C, and an air-to-biomass mass ratio (A/B) of 1.2. The average gas production could reach 2.67 m3/kg, with the average low calorific value of 5.1 MJ/m3. The average hydrogen content could reach 20 %, with the average H2/CO ratio of 2. The average effective gasification efficiency could reach 69.72 %. Compared with air gasification, the proposed air-steam gasification was equivalent to the use of 1 kWh of electricity to produce 2.4 kWh of electricity. Combining market research, the price of steam produced by the proposed system was approximately 70 CNY/t less than when using natural gas. This study aims to provide a technical reference for improving the performance of biomass gasification in practical applications.

Diverse Effects of SO2-Induced Pt-O-SO3 on the Catalytic Oxidation of C3H6 and C3H8.

The effects of sulfur dioxide (SO2) in the catalytic purification of short-chain hydrocarbons are still controversial, and the exact role of SO2 on adsorption and reaction pathways during the catalytic oxidation of different volatile organic compounds (VOCs) remains unclear. Herein, a three-dimensional ordered macroporous Ce0.8Zr0.2O2 supported Pt nanoparticle monolithic catalyst (Pt/OM CZO) was synthesized to investigate these effects. Our findings uncover the diverse effects of SO2: Upon SO2 treatment, the coupling between the S 3p and Pt 5d orbitals promotes the Pt-O-SO3 structure in situ formed on the catalyst surface. The propene (C3H6) molecule readily binds with the oxygen atom in Pt-O-SO3, resulting in the accumulation of acetone and carbon deposition, thereby hindering C3H6 oxidation. Conversely, a cleaved oxygen atom within the Pt-O-SO3 structure enhances propane (C3H8) adsorption and activates the C-H bond, facilitating C3H8 oxidation. These insights are pivotal for advancing the frontier of sulfur-tolerant catalysts, addressing both economic and environmental challenges.

Surface activity, aggregation behaviour and wettability of mixtures of perfluorobranched short-chain gemini quaternary ammonium surfactant and hydrocarbon anionic surfactants in dilute solution

The hydrophobic and oleophobic properties of perfluorobranched short chains are similar to those long chain fluorocarbons (fluorocarbon chain length ≥ 7), and their environmentally friendly properties make them good alternatives to traditional perfluorooctyl derivatives. For this purpose, a novel perfluorinated branched short chain quaternary ammonium gemini surfactant (PBFS) with high surface activity was synthesized, and the surface properties, aggregation behavior, wetting performance and adsorption performance of the complex system of PBFS and sodium octyl sulfate (SOS) were systematically studied. PBFS exhibited superior surface activity in aqueous solution with the critical micelle concentration (CMC) of 0.1667 mmol/L and the corresponding surface tension (γCMC) of 20.17 mN/m. Moreover, despite the fact that the mixing of PBFS and SOS was not ideal, the two still had the good synergistic effect: the CMC of the compounding solution was reduced to 0.0072 mmol/L and γCMC was 16.01 mN/m when the compounding ratio (CF: CH) was 1:8. And the composite solution could completely wet low surface energy polytetrafluoroethylene (PTFE) plates at 1 mmol/L, and could also wet PTFE plates at extremely low concentrations (0.0625 mmol/L), showing good wetting performance.

Tailoring performance for biomass tar reforming using magnetically assisted gliding arc discharges

Gliding arc discharge (GAD) holds significant potential for energy and environmental applications, particularly in biomass tar reforming. In this study, we developed two GAD reactors coupled with a magnetic field for biomass tar reforming. The reactors were designed with two different configurations by varying the magnetic field direction relative to the electrodes: magnetically accelerated gliding arc discharge (MAGAD) and magnetically stabilized gliding arc discharge (MSGAD). The reforming performance and discharge characteristics of these two configurations were systematically evaluated and compared with those of a normal GAD (NGAD). MAGAD demonstrated superior reforming performance, achieving the highest conversion for toluene (71.4 %) and phenol (87.5 %), as well as the highest yields of H2 (22.4 %) and C2H2 (12.6 %) at a magnetic field intensity of 133 mT. In contrast, MSGAD achieved the highest energy yield (47.1 g/kWh) but exhibited lower tar conversion due to reduced discharge power. In the MAGAD system, the magnetic field generates a synergistic effect between the Lorenz force and gas thrust, accelerating and elongating the arc along the electrodes. This results in increased discharge power and frequency, as well as an expanded discharge region. This leads to the generation of more reactive species, which enhances the breakdown of benzene rings into short-chain hydrocarbons and reduces the formation of liquid byproducts. These findings demonstrate the potential of manipulating magnetic fields to optimize GAD systems for efficient biomass tar reforming, offering a promising strategy to improve the performance of plasma-based chemical reactions.

Microbial anabolic and catabolic utilization of hydrocarbons in deep subseafloor sediments of Guaymas Basin.

Guaymas Basin, located in the Gulf of California, is a hydrothermally active marginal basin. Due to steep geothermal gradients and localized heating by sill intrusions, microbial substrates like short-chain fatty acids and hydrocarbons are abiotically produced from sedimentary organic matter at comparatively shallow depths. We analyzed the effect of hydrocarbons on uptake of hydrocarbons by microorganisms via nano-scale secondary ion mass spectrometry (NanoSIMS) and microbial sulfate reduction rates (SRR), using samples from two drill sites sampled by IODP Expedition 385 (U1545C and U1546D). These sites are in close proximity of each other (ca. 1km) and have very similar sedimentology. Site U1546D experienced the intrusion of a sill that has since then thermally equilibrated with the surrounding sediment. Both sites currently have an identical geothermal gradient, despite their different thermal history. The localized heating by the sill led to thermal cracking of sedimentary organic matter and formation of potentially bioavailable organic substrates. There were low levels of hydrocarbon and nitrogen uptake in some samples from both sites, mostly in surficial samples. Hydrocarbon and methane additions stimulated SRR in near-seafloor samples from Site U1545C, while samples from Site U1546D reacted positively only on methane. Our data indicate the potential of microorganisms to metabolize hydrocarbons even in the deep subsurface of Guaymas Basin.

Co-pyrolysis of animal manure and plastic waste study using TG-FTIR analysis

In this paper, the co-pyrolysis of blends of animal manure (AM) and high-density polyethylene (HDPE) waste was investigated using micro-thermal analysis techniques. Thermogravimetry coupled with Fourier-transform infrared spectroscopy was used to study the process kinetics and potential synergistic effects during co-pyrolysis. Dynamic co-pyrolysis experiments of animal manure (AM) and polyethylene (PE) blends in proportions of (90:10 %) and (80:20 %) were conducted at heating rates of 5, 10, 15, and 20 °C/min under an N2 atmosphere. The process was analyzed and compared to the results obtained in the pyrolysis of pure components. AM and PE co-pyrolysis exhibited a synergic effect on the pyrolysis process, leading to a favorable change in the CPI pyrolysis initiation index. This was observed in the FTIR, shifting maximum devolatilization peaks by 14 °C towards lower temperatures and a lower activation energy of the main pyrolysis stage, with a decrease from 341.49±4.65 kJ/mol to 273.04±6.93 kJ/mol after the addition of 20 wt% PE to the blend. During co-pyrolysis, the main compounds observed in the FTIR absorption spectra were CO2, CO, CH4, NH3, and aromatic hydrocarbons from AM pyrolysis. Additionally, there was an increase in CH4 and short-chain hydrocarbons due to the PE pyrolysis.

Modification of the N-methyl-4,5-diazacarbazole D-π-A with a π-conjugated bridge to enhance excited-state properties for superior utilization in green energy applications: A theoretical approach

In organic photovoltaic technology, tailoring the acceptor or donor unit to enhance intramolecular charge transfer is a well-known approach, however, the effect of modifying conjugated bridge units is an underdeveloped phenomenon. In this study, this approach has been focused, where a series of conjugated bridges including, a) electron-excessive heterocycles, b) electron-deficient heterocycles, and c) short-chain unsaturated hydrocarbons have been substituted from thiophene bridge-containing D-π-A; N-methyl-4,5-diazacarbazole (donor) and bay-annulated indigo (acceptor) molecule. This quantum chemical study aims to investigate the effect of various types of π-conjugated bridges on the electronic structure and solar cell activity of already reported material. The selected π-conjugated bridges include electron-excessive (furan, pyrrole, & thiophene) and electro-deficient (diazine, tetrazine, & pyridine) heterocycles, and short-chain hydrocarbons (ethylene & ethyne). The optimized structural parameters e.g., dihedral angles (θ), distortion energies (Edis), & bond distances (d), and electronic behaviour i.e., Frontier Molecular Orbitals (FMO), Electrostatic Potentials (ESP), Density of States (DOS) spectra, dipole moments (μ), and absorption spectra of the hypothetically designed molecules are estimated using density functional theory calculations. The solar cell proficiency is investigated with transition dipole moment (μT), reorganization energy (RE), Transition density matrix (TDM), exciton binding energy (Eb), and open circuit voltage (Voc). Our finding encompassed that our designed D-π-A molecules show significant improvement in their electronic behaviour, especially when the thiophene bridge of the reference molecule is substituted with the excess electron heterocycles, especially pyrrole. The HOMO-LUMO gap of this particular molecule (MPy) is reduced to 2.07 eV, resulting in the significant charge transfer between donor and acceptor units (0.15 e-). Moreover, the results of RE, TDM, Eb, and Voc also support the high solar cell efficiency of pyrrole-containing molecules.

ReaxFF reactive molecular dynamic and density functional theory study on the co-pyrolysis mechanism of waste 1,1,1,2-tetrafluoroethane and waste plastics to produce high value-added chemicals and fuels

Pyrolysis is one of the potential way for the degradation of hydrofluorocarbons, but it is difficult to make effective use of the complex pyrolysis products. The addition of plastics can provide sufficient hydrogen source for the degradation of hydrofluorocarbons to generate the high value-added chemicals and fuels. Density functional theory calculation and reactive molecular dynamic simulation are employed to investigate the co-pyrolysis mechanism of 1,1,1,2-tetrafluoroethane and low-density polyethylene in this work. The results show that the H atoms provided by low-density polyethylene promote the defluorination reactions of 1,1,1,2-tetrafluoroethane to generate HF and short chain hydrocarbons, and the number of F atoms in HF molecules accounted for nearly 80 % of the whole reaction system, achieving a better defluorination effect. The defluorination rate of 1,1,1,2-tetrafluoroethane and plastics co-pyrolysis is more than 5 times that of pure 1,1,1,2-tetrafluoroethane pyrolysis. The main co-pyrolysis products of 1,1,1,2-tetrafluoroethane and low-density polyethylene are H2, HF and short chain hydrocarbons, the purpose of hydrofluorocarbons degradation into high value-added chemicals and fuels is realized in this study. This work provides a green, effective way for the conversion waste hydrofluorocarbons and waste plastics into high value-added chemicals and fuels, and achieves the conversion of waste hydrofluorocarbon refrigerants to more economical products.

Characterization of the closely related Arabidopsis thaliana β-ketoacyl-CoA synthases KCS3, KCS12 and KCS19.

The cuticle, consisting of cuticular wax and cutin, is a lipid membrane that seals the plant surface against environmental stress. β-Ketoacyl-CoA synthases (KCSs) are condensing enzymes catalyzing crucial reactions elongating hydrocarbon chains into precursors for various cuticular wax components. Although many KCS genes were well characterized in various species, the functions of the closely related Arabidopsis KCS3, KCS12, KCS19 enzymes remained unclear. Here, we found KCS3 preferentially expressed in growing organs, especially in guard cells. kcs3 mutants and kcs3kcs12 double mutants displayed sepal fusion phenotypes, suggesting defects in cuticle formation. The mutants had decreased amounts of wax components with relatively short hydrocarbon chains in the developing organs but increased levels of wax compounds in mature organs. In contrast, kcs19 mutants showed seed fusion phenotypes and altered chain length distributions in seed suberin. Taken together, our results show that KCS12 and KCS3 share redundant functions in flower development, while KCS19 is involved in seed coat formation. All three condensing enzymes are involved in the elongation of C>18 hydrocarbon chains in young, actively expanding tissues.

In-situ conversion of low-to medium-mature organic-rich shales by nuclear irradiation

Organic-rich shale is an important potential energy resource in the world. In situ organic-rich shale conversion has been discovery highly efficient to convert kerogen to oil through electric heating. However, the heating method is highly energy-consuming and less economically feasible. Finding other replaceable technique becomes an urgent task. Low-to medium-mature shale samples from continental freshwater and saline lake were irradiated by a cobalt-60-source with energy doses of 0.5 kGy, 1 kGy, 10 kGy, 100 kGy, and 1000 kGy. The changes of minerals and organic matters in shale were thoroughly monitored using various analysis including rock thin section, X-ray diffraction, scanning electron microscope, TOC, pyrolysis test, gas chromatography, and infrared spectrum. The results show that the TOCs of shale samples decrease gradually as irradiation doses increase and their organic matter functional group compositions change greatly. Irradiation reduces the content of long-chain hydrocarbons (especially C30+) in shale and generates short-chain hydrocarbons and gaseous substances. M-1 (Santanghu shale) and ZK-1 (Ordos shale) shows largest yields after irradiation, amount to 62 kg and 130 kg per ton shale respectively. Those two samples are S-rich shale which may have low activation energy for petroleum transformation from kerogen and thus benefit for hydrocarbon generation after irradiation. Therefore, we infer that the irradiation method can provide a new idea for the effective development of medium-to low-mature shale oil in the future, especially for those shales depositing at S-rich, saline, deep to semi-deep lacustrine environments.

Impact of conjugation to different lipids on the lymphatic uptake and biodistribution of brush PEG polymers

Delivery to peripheral lymphatics can be achieved following interstitial administration of nano-sized delivery systems (nanoparticles, liposomes, dendrimers etc) or molecules that hitchhike on endogenous nano-sized carriers (such as albumin). The published work concerning the hitchhiking approach has mostly focussed on the lymphatic uptake of vaccines conjugated directly to albumin binding moieties (ABMs such as lipids, Evans blue dye derivatives or peptides) and their subsequent trafficking into draining lymph nodes. The mechanisms underpinning access and transport of these constructs into lymph fluid, including potential interaction with other endogenous nanocarriers such as lipoproteins, have largely been ignored. Recently, we described a series of brush polyethylene glycol (PEG) polymers containing end terminal short-chain or medium-chain hydrocarbon tails (1C2 or 1C12, respectively), cholesterol moiety (Cho), or medium-chain or long-chain diacylglycerols (2C12 or 2C18, respectively). We evaluated the association of these materials with albumin and lipoprotein in rat plasma, and their intravenous (IV) and subcutaneous (SC) pharmacokinetic profiles. Here we fully detail the association of this suite of polymers with albumin and lipoproteins in rat lymph, which is expected to facilitate lymph transport of the materials from the SC injection site. Additionally, we characterise the thoracic lymph uptake, tissue and lymph node biodistribution of the lipidated brush PEG polymers following SC administration to thoracic lymph cannulated rats. All polymers had moderate lymphatic uptake in rats following SC dosing with the lymph uptake higher for 1C2-PEG, 2C12-PEG and 2C18-PEG (5.8%, 5.9% and 6.7% dose in lymph, respectively) compared with 1C12-PEG and Cho-PEG (both 1.5% dose in lymph). The enhanced lymph uptake of 1C2-PEG, 2C12-PEG and 2C18-PEG appeared related to their association profile with different lipoproteins. The five polymers displayed different biodistribution patterns in major organs and tissues in mice. All polymers reached immune cells deep within the inguinal lymph nodes of mice following SC dosing. The ability to access these immune cells suggests the potential of the polymers as platforms for the delivery of vaccines and immunotherapies. Future studies will focus on evaluating the lymphatic targeting and therapeutic potential of drug or vaccine-loaded polymers in pre-clinical disease models.

Chemical structure of hydrocarbons significantly affects removal performance and microbial responses in gas biotrickling filters

The control of emissions of short-chain hydrocarbons with different structures is critical for the petrochemical industry. Herein, three two-carbon-containing (C2) hydrocarbons, ethane, ethylene, and acetylene, were chosen as pollutants to study the effects of chemical structure of hydrocarbons on removal performance and microbial responses in biotrickling filters. Results showed that the removal efficiency (RE) of C2 hydrocarbons followed the sequence of acetylene > ethane > ethylene. When the inlet loading rate was 30 g/(m3·h) and the empty bed residence time was 60 s, the RE of ethane, ethylene, and acetylene was 57 ± 4.0 %, 49 ± 1.0 %, and 84 ± 2.7 %, respectively. The high water solubility resulted in the high removal of C2 hydrocarbons, while a low surface tension enhanced the removal of C2 hydrocarbons. Additionally, the microbial community, enzyme activity, and extracellular properties of microorganisms also contributed to the difference in C2 hydrocarbon removal. These results could be referred for the effective control of light hydrocarbon emissions.

Removal of perfluoroalkyl acids from aqueous media by surfactant-modified clinoptilolites.

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are environmentally persistent, bioaccumulating, and toxic compounds that have attracted global attention. It is challenging to reduce the residual concentrations of these compounds to safe discharge limits. In this study, batch experiments were performed to evaluate natural clinoptilolite and clinoptilolites modified (MC) with cetylpyridinium chloride (CPC-MC), didodecyldimethylammonium bromide (DDAB-MC), hexadecyltrimethylammonium bromide (HDTMA-MC), and tetramethylammonium chloride (TMA-MC) as cost-effective aqueous PFAS adsorbents. The removal capacities of the adsorbents for the majority of the PFASs decreased in the following order: DDAB-MC > CPC-MC ≫ modified natural clinoptilolite with hexadecyltrimethyl ammonium bromide (HDTMA-MC) ≫ modified natural clinoptilolite with tetramethylammonium chloride (TMA-MC) ≈ natural clinoptilolite modified with NaCl (NC). In particular, CPC-MC and DDAB-MC reduced PFASs concentration in 50μg/L by up to 98% for perfluorooctane sulphonate. Within 30min, CPC-MC (30.5μg/L) and DDAB-MC (32.1μg/L) met the PFOS water quality criterion of 36μg/L in inland surface waters. Both adsorbents met this criterion at the highest solution volume (40mL) and 0.125g/L (solid-to-liquid ratio of 1:8). PFASs with short hydrocarbon chains competed more for adsorption. PFASs with sulphonate functional groups were also adsorbed more than carboxyl groups in single- and multi-PFAS solutions. The modified surfaces of clinoptilolites controlled PFAS adsorption through hydrophobic and electrostatic interactions. PFAS removal with surfactant-modified clinoptilolites is cost-effective and protects aquatic environments by using surplus natural materials.

Relevance of shock waves derived from asteroid impacts in the atmosphere of the early Earth in the production of compounds of astrobiological interest

Abstract The generation of organic compounds relevant to the origin of living beings is easily achieved if reducing conditions exist in the environment; however, proposed models of primitive atmospheres do not favour these conditions. This work considers the quantity and possible size of the cosmic bodies that could have impacted the Earth between 4.2 and 3.8 Ga. Different atmospheres (with gases such as CO2, CO, N2, CH4) were experimentally irradiated by an Nd-YAG laser (used to simulate the energy of a shock wave produced by the interaction of a cosmic body with the atmosphere). Although the main products are short-chain, saturated and unsaturated hydrocarbons, hydrogen cyanide (HCN) is the most abundant in some atmospheres. HCN is an important precursor of the organic molecules relevant to chemical evolution. According to our calculations, between 1023 and 1025 g of HCN could have been produced by the energy released to the atmosphere from the entry of cosmic objects between 4.2 and 3.8 Ga. Therefore, this shock wave energy could play an important role in the processes of chemical evolution.

PAS-based analysis of natural gas samples.

Photoacoustic spectroscopy (PAS) is well known for the detection of short-chain hydrocarbons, such as methane, ethane and propane, in the ppm (parts per million) or ppb (parts per billion) range. However, in the production process of natural gas and its combustion in gas-fired devices the composition, especially the concentrations of the main alkanes, plays a decisive role. Gas chromatography (GC) is considered the gold standard for natural gas analysis. We present a method to analyze natural gas samples by PAS. Furthermore, we describe a method to prepare storage gas samples, which are usually under atmospheric pressure, for PAS analysis. All measurements are validated by means of GC. The investigation allows conclusions to be drawn to what extent PAS is suitable for the investigation of natural gas samples.

Evolution and speciation transformation of chlorine during automobile shredder residue pyrolysis

Disposal of automobile shredder residue (ASR) via pyrolysis enables the recovery of valuable products; however, the production of hazardous pollutants and low-value products is inevitable due to its high chlorine content. In this work, chlorine evolution behavior and the conversion mechanism during ASR pyrolysis between 480 and 600 °C were systematically studied. The experimental results for organic chlorine (Org-Cl) showed that released chlorinated gases were complex, and HCl only accounted for 35% of the gas phase products, while short-chain hydrocarbons with carbon atoms between two and four accounted for 52%. Chlorine was predominantly retained in the char, and Org-Cl was the primary contributor to the residual chlorine, accounting for over 50% of the char. The content of inorganic chlorine (InO-Cl) was low in the raw sample but significantly increased in the char. Through the distinction between organic and inorganic chlorine content in char, it was confirmed that Org-Cl could be converted to InO-Cl due to complex secondary reactions with metallic compounds. The conversion was favored by increasing the Org-Cl content and the temperature. Our findings clarified the evolution mechanism of chlorine and the transformation from Org-Cl to InO-Cl, thus providing guidance for chlorine regulation and the efficient recycling of metal resources.

Functionalisation of brush polyethylene glycol polymers with specific lipids extends their elimination half-life through association with natural lipid trafficking pathways

Polymeric prodrugs have been applied to control the delivery of various types of therapeutics. Similarly, conjugation of peptide therapeutics to lipids has been used to prolong systemic exposure. Here, we extend on these two approaches by conjugating brush polyethylene glycol (PEG) polymers with different lipid components including short-chain (1C2) or medium-chain (1C12) monoalkyl hydrocarbon tails, cholesterol (Cho), and diacylglycerols composed of two medium-chain (2C12) or long-chain (2C18) fatty acids. We uniquely evaluate the integration of these lipid-polymers into endogenous lipid trafficking pathways (albumin and lipoproteins) and the impact of lipid conjugation on plasma pharmacokinetics after intravenous (IV) and subcutaneous (SC) dosing to cannulated rats. The IV and SC elimination half-lives of Cho-PEG (13 and 22 h, respectively), 2C12-PEG (11 and 17 h, respectively) and 2C18-PEG (12 h for both) were prolonged compared to 1C2-PEG (3 h for both) and 1C12-PEG (4 h for both). Interestingly, 1C2-PEG and 1C12-PEG had higher SC bioavailability (40 % and 52 %, respectively) compared to Cho-PEG, 2C12-PEG and 2C18-PEG (25 %, 24 % and 23 %, respectively). These differences in pharmacokinetics may be explained by the different association patterns of the polymers with rat serum albumin (RSA), bovine serum albumin (BSA) and lipoproteins. For example, in pooled plasma (from IV pharmacokinetic studies), 2C18-PEG had the highest recovery in the high-density lipoprotein (HDL) fraction. In conclusion, the pharmacokinetics of brush PEG polymers can be tuned via conjugation with different lipids, which can be utilised to tune the elimination half-life, biodistribution and effect of therapeutics for a range of medical applications. Statement of significanceLipidation of therapeutics such as peptides has been employed to extend their plasma half-life by promoting binding to serum albumin, providing protection against rapid clearance. Here we design and evaluate innovative biomaterials consisting of brush polyethylene glycol polymers conjugated with different lipids. Importantly, we show for the first time that lipidated polymeric materials associate with endogenous lipoprotein trafficking pathways and this, in addition to albumin binding, controls their plasma pharmacokinetics. We find that conjugation to dialkyl lipids and cholesterol leads to higher association with lipid trafficking pathways, and more sustained plasma exposure, compared to conjugation to short and monoalkyl lipids. Our lipidated polymers can thus be utilised as delivery platforms to tune the plasma half-life of various pharmaceuticals.

Novel Ionic Liquid Synthesis of Bimetallic Fe–Ru Catalysts for the Direct Hydrogenation of CO2 to Short Chain Hydrocarbons

The selective hydrogenation of CO2 for the production of net-zero fuels and essential chemical building blocks is a promising approach to combat climate change. Key to this endeavor is the development of catalysts with high activity and selectivity for desired hydrocarbon products in the C2–C5 range. The process involves a two-step reaction, starting with the reverse water–gas shift (RWGS) reaction and proceeding to the Fischer–Tropsch reactions under high pressure. Understanding the catalyst features that control the selectivity of these pathways is crucial for product formation, as well as identifying morphological changes in the catalysts during the reaction to optimize their performance. In this study, an innovative method for synthesizing iron–ruthenium bimetallic catalysts is introduced, capitalizing on the synergistic effects of these metals as active phases. This method leverages ionic liquids as solvents, allowing for the precise and uniform distribution of active metal phases. Advanced characterizations and extensive catalytic tests have demonstrated that the use of ionic liquids outperformed traditional colloid-based techniques, resulting in superior selectivity for target hydrocarbons. The success of this inventive approach not only advances the field of CO2 hydrogenation catalysis, but also represents a significant stride towards sustainable e-fuel production.

An ex vivo headspace gas chromatography-mass spectrometry method for the determination of short-chain siloxanes in silicon oil tamponades used in ophthalmic surgery

Being able to facilitate retinal reattachment by preventing water migration into the subretinal space, silicone oils are widely used as long-term intraocular tamponade to treat cases of retinal detachment. Various commercial tamponades constituted by linear polydimethylsiloxane polymers with different molecular weights and cyclic impurities are available. In this study, for the first time, an untargeted headspace-gas-chromatography-mass spectrometry (HS-GC-MS) method was developed to identify low-molecular weight contaminants in three different types of silicone oil tamponades, namely Siluron 2000, RS-OIL ECS5000 and Densiron Xtra. Both commercial and post-operative tamponades were analysed to screen for the different classes of compounds present in the samples. The most abundant classes were short-chain siloxanes, fluorinated compounds, and hydrocarbons. To quantify the siloxanes present in the samples, a targeted HS-GS-MS was optimized using a central composite design and validated according to guidelines for bioanalytical methods. Lower limits of quantification in the low μg/L range, good precision with RSD% < 12% and accuracy with recovery rates in the 81 ( ± 7) – 96 ( ± 4) % range were achieved. Short-chain siloxanes were quantified in both commercial and post-operative tamponades, being the RS-OIL ECS5000 characterized by the highest concentration levels of the investigated analytes. By contrast, Densiron Xtra tamponades showed the lowest amount of short-chain siloxanes, observing a general decrease in their concentration levels according to the residence time in the eyes.