Lower Alkyl Research Articles

Hydrophobic and thermal insulation properties of modified wood based on ATRP polymerisation

Balsa wood, despite being a cost-effective insulation material, has limited applications due to its inherent hydrophilicity. This study introduces an innovative technique for the in-situ growth of low surface energy long alkyl chain segments on balsa wood using the atom transfer radical polymerization (ARGET-ATRP) method, which not only provides durable and stable hydrophobicity but also preserves its natural texture, mechanical strength, and thermal insulation. The resulting hydrophobic wood demonstrated exceptional hydrophobicity in diverse environments, with a water contact angle up to 141.3° and a contact angle decrease of no more than 10.47 % after 150 min, confirming its hydrophobic stability. Furthermore, axial thermal conductivity of the wood was as low as 0.1012 W/m·K, the axial compressive strength decreased by only 12.8 %, further evidencing the retention of its mechanical properties. This simple yet effective strategy of in-situ alkyl chain growth on balsa wood not only preserves its structure but also opens new avenues for the multifunctional development of biomaterials.

Impact of deodorisation time and temperature on the removal of different MOAH structures: a lab-scale study on spiked coconut oil

Vegetable fats and oils are prone to contamination by mineral oil hydrocarbons due to the lipophilic and ubiquitous character of the latter. As the aromatic fraction of these hydrocarbons, MOAH, is associated with carcinogenicity, mutagenicity, and detrimental effects on foetal development, finding strategies to limit or reduce their contamination is highly relevant. Deodorisation (i.e. a refining step) has shown the ability to remove MOAH < C25 in vegetable fats and oils, but there is little information about the structures removed. Therefore, the present study investigated the impact of deodorisation conditions on the removal of different structures of MOAH in spiked coconut oil. An inscribed central composite design was built with time and temperature as variables (0.5-4h, 150-240 °C), while pressure (3 mbar) and steam flow (1 g water/g oil per hour) were kept constant. The analysis of MOAH in the oil was performed using a fully automated liquid chromatography coupled with two parallel comprehensive two-dimensional gas chromatography systems with flame ionisation and time-of-flight mass spectrometric detection. Response surfaces plotting the MOAH loss according to time and temperature were built for different MOAH fractions. The latter were defined based on the number of aromatic rings (>3 or ≤3) and the number of carbon atoms present (C16-C20, C20-C24, C24-C35, C35-C40). It was found that at 200 °C, compounds < C24, including weakly alkylated triaromatics, could be reduced to below the limit of quantification, while at 230 °C, it was possible to remove >60% of the C24-C35 fraction, including pentaromatics of low alkylation.

Reversing the Trend: Deciphering Self-Assembly of Unconventional Amphiphiles Having Both Alkyl-Chain and PEG.

In the field of molecular self-assembly, the core of an assembly is always made up of hydrophobic moiety like a long alkyl chain, whereas the outer part has always been a hydrophilic moiety such as poly(ethylene glycol) (PEG), or charged species. Hence, reversing the trend to manifest self-assembled structures with a PEG core and a surface consisting of alkyl chains in aqueous system is incredibly challenging. Herein, we architected a unique class of cationic bolaamphiphiles containing low molecular weight PEG and alkyl chains of different lengths. The bolaamphiphiles spontaneously form vesicles without external stimuli. These vesicles are unprecedented because PEG makes up the vesicle core, while the alkyl chains appear on the vesicles' exterior. Hence, this particular design reverses the usual trend of self-assembly formation. The vesicle size increases with the increase in alkyl chain-length. To our great surprise, we obtained large micelles for longest alkyl-chain amphiphile, which in turn act as a gemini amphiphile. The shift from a particular bolaamphiphile to gemini amphiphile with the variation of alkyl chain is also unexplored. Therefore, this specific class of self-assembled structure would compound a new paradigm in molecular self-assembly and supramolecular chemistry.

Structural properties and adsorption performance relationship towards three categories of lignin and their derived biochar

The growing interest in utilizing lignin for dye removal has gained momentum, but there is limited information on the intricate relationship between lignin structural characteristics and adsorption efficacy, especially for its biochar derivatives. This study focused on three types of lignin and their corresponding biochar derivatives. Among them, ZnCl2-activated acidic/alkali densified lignin preparation of lignin-derived active carbon exhibited superior adsorption performance, achieving 526.32 mg/g for methylene blue and 2156.77 mg/g for congo red. Its exceptional adsorption capacity was attributed to its unique structural properties, including low alkyl and O-alkyl group content and high aromatic carbon levels. Furthermore, the adsorption mechanisms adhered to pseudo-second-order kinetics and the Langmuir model, signifying a spontaneous process. Intriguingly, lignin-derived active carbon also demonstrated remarkable recovery capabilities. These findings provide valuable insights into the impact of structural attributes on lignin and its biochar's adsorption performance.

Detailed Comparison of Xenon APPI (9.6/8.4 eV), Krypton APPI (10.6/10.0 eV), APCI, and APLI (266 nm) for Gas Chromatography High Resolution Mass Spectrometry of Standards and Complex Mixtures.

Photoionization schemes for mass spectrometry, either by laser or discharge lamps, have been widely examined and deployed. In this work, the ionization characteristics of a xenon discharge lamp (Xe-APPI, 9.6/8.4 eV) have been studied and compared to established ionization schemes, such as atmospheric pressure chemical ionization, atmospheric pressure photoionization with a krypton discharge lamp (Kr-APPI, 10.6/10 eV) and atmospheric pressure laser ionization (266 nm). Addressing the gas-phase ionization behavior has been realized by gas chromatography coupled to high-resolution mass spectrometry without the usage of a dopant. For standard substances, it has been found that Xe-APPI is able to ionize a broad range of polycyclic aromatic hydrocarbons as well as their heteroatom-containing and alkylated derivatives. However, thiol and ester compounds could not be detected. Moreover, Xe-APPI revealed a high tendency to generate oxygenated artifacts, most likely due to a VUV absorption band of oxygen at 148 nm. Beneficially, almost no chemical background, commonly caused by APCI or Kr-APPI due to column blood, plasticizers or impurities, is observed. This advantage is noteworthy for evolved gas analysis without preseparation or for chromatographic coelution. For the complex mixtures, Xe-APPI revealed the predominant generation of radical cations via direct photoionization with a high selectivity toward aromatic core structures with low alkylation. Interestingly, both Xe-APPI and Kr-APPI could sensitively detect sterane cycloalkanes, validated by gas chromatographic retention. The narrowly ionized chemical space could let Xe-APPI find niche applications, e.g., for strongly contaminated samples to reduce the background.

Efficient and green esterification approach for determining of sodium alkylbenzene sulfonates in dry extracts

Linear alkylbenzenesulfonate is an anionic surfactant widely used in detergents and cleaners, both in industrial and household applications as well as a component of pesticides and fertilizers. In this work, the universal effective green approach for sodium alkylbenzenesulfonate esterification to determine these substances in a form of their volatile derivatives by gas chromatography coupled with electron ionization mass-spectrometry (GC–MS) is presented. The approach provides a simple conversion of sodium alkylbenzene sulfonates to a form of alkylbenzenesulfonic acid methyl esters in 98% yield for 20 min at 24 °C. The yield was estimated using high performance liquid chromatography-ultraviolet detection. Trimethyl orthoformate (125 µl) was used as low toxicity alkylation reagent. The obtained volatile derivatives might be redissolved in n-hexane and analyzed by GC–MS in selective ion monitoring mode. The limit of quantification of 20 alkylbenzenesulfonate isomer sum was estimated as 25 ng μL–1 of the analyzed extract. The approach might be applied to food, environmental and biological objects contaminated with alkylbenzene sulfonates. The applicability of the method is shown using dry solvent-free extracts of snow, river sediments, freshwater branching sponge Lubomirskia baikalensis, the whole blood, and widely cultivated plants such as spinach Spinacia oleracea and cucumber Cucumis sativus. The presence of sodium alkylbenzene sulfonates in snow (31.1 ± 1.0 µg L–1) and sediments (208±7 µg g–1 of d.w.) of the world's deepest Lake Baikal tributaries as well as in freshwater sponge (33.6 ± 1.1 µg g–1 of d.w.) was found. The repeatability of measurement is characterized by RSD = 2.24%.

Linking Microbial Decomposition to Dissolved Organic Matter Composition in the Revegetation of the Red Soil Erosion Area

Studying the changes and linkages between dissolved organic matter (DOM) and microorganisms in soils during vegetation restoration will help to understand the role of vegetation restoration in soil carbon sequestration and thus improve the understanding of the global soil carbon cycle. Soil DOM molecules were characterized by Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and the results showed that the soil DOM consisted mainly of lignin/carboxylic rich alicyclic molecule (CRAM)-like structures, while the ratios of lipids and aliphatic/protein decreased in sequence with recovery time. Lipids and aliphatic/proteins with high H/C DOM (labile DOM) degrade preferentially, while lignin/CRAM-like structures and tannins with low H/C DOM (recalcitrant DOM) are recalcitrant during vegetation restoration. With the restoration of vegetation, DOM molecules tend to be diversified and complicated, and DOM compounds with low double bond equivalent (DBE), low aromatic, and low alkyl structures will be converted into persistent organic matter with high carbon numbers and high DBE. The diversity of soil microorganisms was determined by high-throughput sequencing. The results showed that the abundance and diversity of soil bacteria increased significantly after revegetation, while the abundance and diversity of soil fungi began to increase when the ecosystem became a more mature coniferous forest. The soil microbial community exhibited complex connectivity and strong interaction with DOM molecules during vegetation restoration. As most of the DOM molecules are recalcitrant, vegetation restoration facilitates C sequestration in the soil, thereby contributing to climate change mitigation.

When hydrogen is slower than methane to ignite

Hydrogen (H2) is known to be the fastest fuel to ignite among all practical combustion fuels. In this study, for the first time, longer ignition delay times (IDTs) for the H2 and H2 blended CH4 mixtures were measured compared to those for pure CH4. This work investigates the ignition characteristics of H2, CH4, and 50% CH4/50% H2 mixtures using a rapid compression machine at pressures ranging from 20 to 50 bar and at equivalence ratios (φ) from 0.5 to 2.0 in air in the temperature range 858–1080 K. The experimental IDTs are simulated using a newly updated kinetic mechanism, NUIGMech1.3, and good agreement is observed. At lower temperatures the IDTs of H2, CH4, and the 50% CH4/50% H2 mixtures are similar to one another, and the IDTs of the 50% CH4/50% H2 mixtures are longer than those for pure CH4 at temperatures below 930 K. At temperatures below 890–925 K, depending on the operating pressure and equivalence ratio, the hydrogen mixtures are the slowest to ignite, with IDTs being 2.5 times longer than those recorded for CH4 at a pressure of 40 bar at 890 K for φ = 1.0, and at 875 K for φ = 2.0. At low temperatures alkyl (Ṙ = ĊH3 and Ḣ) radicals add to O2 producing RȮ2 radicals, which then react with HȮ2 radicals forming ROOH (H2O2 and CH3OOH) and O2. For H2, the self-recombination of HȮ2 radicals leads to chain propagation which inhibits reactivity, whereas for CH4, the reaction between RȮ2 (CH3OȮ) and HȮ2 leads to chain branching, increasing reactivity. Furthermore, CH3OOH decomposes more easily to produce CH3Ȯ and ȮH radicals than does H2O2 to produce two ȮH radicals. Thus, mixtures containing higher H2 concentrations are slower to ignite compared to those with higher CH4 concentrations at low temperatures.

Synthesis of alkyl polyamine with different functional groups and its montmorillonite swelling inhibition mechanism: Experiment and density functional theory simulation

In this work, low molecular weight alkyl polyamine (tris(2-methylaminoethyl)amine (TSA), hexamethyltris(2-aminoethyl)amine (TTA), nonamethyltris(2-aminoethyl)amine (TQA)) with different functional groups and the same hydrophobic chain was synthesized using tris(2-aminoethyl)amine (TPA). X-ray diffraction, scanning electron microscopy, X-Photoelectron spectroscopy, transmission electron microscopy, contact angle, and density functional theory simulation were used to investigate the montmorillonite swelling inhibition mechanisms. The results of the experiments showed that a small amount of TPA, TSA, TTA, and TQA can significantly reduce the basal spacing of montmorillonite (Mt). The basal spacing of montmorillonite did not change with increasing the inhibitor concentration. The basal spacing of Mt-TPA, Mt-TSA, and Mt-TTA had some differences in the dry and wet states, but there was no difference in Mt-TQA. This observation indicated that TPA, TSA and TTA exhibited a three-dimensional spatial configuration in the lamellar spacing of montmorillonite, while TQA was inserted into the space of montmorillonite layer in a single flat layer. As more amine groups were substituted by the methyl groups, the spatial configuration of inhibitors changes from a three-dimensional to a two-dimensional planar structure. The higher the number of hydrogen atom substitutions in the primary amine group by methyl groups, the larger the contact angle, and the stronger the hydrophobic capacity except for the quaternary ammonium groups. The simulation results indicated that the higher the number of substitutions, the larger the adsorption energy. Therefore, inhibitors with a quaternary amine group would have better inhibition performance.

Seasonal variations of low molecular alkyl amines in PM2.5 in a North China Plain industrial city: Importance of secondary formation and combustion emissions

Atmospheric amines have unique acid-neutralizing capacity and play an important role in atmospheric chemical reactions. An integrated observation of PM2.5 samples (from Dec 2015 to Nov 15, 2016) was conducted in a typical industrial city (Xuzhou), China. Concentrations of total measured amines (∑amines, including methylamine (MA), ethylamine (EA), dimethylamine (DMA), propanamine (PA) and trimethylamine (TMA) + diethylamine (DEA)) were 172.0 ± 98.2 ng m−3, accounting 1.5 ± 0.6 ‰ of PM2.5 mass. ∑amines were higher in winter (249.0 ± 112.3 ng m−3) and spring (192.4 ± 75.9 ng m−3) than in summer (114.7 ± 33.3 ng m−3) and autumn (103.7 ± 34.3 ng m−3). Concentrations of MA and EA (the dominant amines) were highest in winter, while DMA, PA and TMA + DEA showed opposite seasonality. EA/MA ratios ranged from 0.04 to 8.7 with a median value of 0.3, and the averaged EA/MA ratio was 2.0 in winter, indicating large contribution of EA. Environmental factors including temperature (T), relative humidity (RH) and atmospheric oxidizing capacity (O3 and Ox represented) were found to influence concentrations of amines in PM2.5. The Positive Matrix Factorization (PMF) model identified secondary products (41.6 %), combustion emissions (39.8 %), soil and waste incineration emissions (13.2 %) and biological emissions and aging products (5.4 %) as the 4 sources of amines in PM2.5. MA was mainly secondary products (82.5 %) and had high contribution of local secondary formation, while EA was mainly derived from combustion emissions (83.7 %) and influenced by regional transportation. In winter, combustion emissions (including coal combustion, biomass burning and traffic emissions, contributed 57.7 %) surpassed secondary products (31.6 %) as the predominant sources of amines, especially under the influence of regional transportation (75.7 %).

Solution properties of hydrophobic derivatives of poly(ethylene-alt-maleic acid)

A library of hydrophobically modified polyelectrolytes was prepared by reacting linear alkyl amines with poly(ethylene-alt-maleic anhydride), followed by hydrolysis of the residual anhydride groups. Every reacted anhydride gives a pendent alkylamide plus a carboxylic acid group, and the result is a comb architecture. The lengths of the alkyl side chains were 3, 6, 8, or 10 carbons. The density of alkyl side chains was expressed as the fraction of anhydride groups reacted with alkyl amines (25 %, 50 %, and 75 %). The dominant factor influencing the aqueous solution properties is the alkyl chain length. C3 polymers had no pyrene receptive hydrophobic domains. C6 and C8 polymers bound pyrene at pH less than 6 and do not give reliable dynamic light scattering (DLS) results. C10 polymers displayed pyrene binding across the pH range and, based on DLS and AFM data, possibly appear as unimolecular nanogel dispersions from pH 7–9. At pH values > 9, our DLS measurements gave low-quality data, whereas at pH less than 7 both DLS and AFM results indicated nanogel aggregation. The C10 polymer properties were surprisingly insensitive to the degree of hydrophobic substitution over the range of 25–75 %. The nanogels with low alkyl contents were slightly more swollen and had high NaCl critical coagulation concentrations compared to the high alkyl content nanogels. These polymers are of particular interest because the non-derivatized maleic moieties in the polymers can form ester linkages to cellulose in an aqueous, catalyst-free process.

One-pot synthesis of superhydrophobic photothermal materials with self-healing for efficient ice removal

Solar energy-facilitated materials are promising to solve energy loss problems for anti-icing/deicing applications by conversion clean solar energy to thermal energy. However, the photothermal conversion performance seriously affect by dirt and liquid contaminants. Moreover, melted ice may wet photothermal materials and freeze again. Herein, durable superhydrophobic photothermal coatings were designed by modifying carbon nanotubes with dodecylamine (DDA) and dopamine via Michael addition reaction. Thanks to the photothermal synergistic effect of PDA and CNTs, the surface temperature of obtain coating rapidly rose to 89.8 °C under 1 kW/m2. Besides, hierarchical structure and low surface energy alkyl long chain of the coating provided excellent self-cleaning property (CA = 162.5 ± 0.9°), which can avoid the adhesion of contaminants and extend the freezing time of ice for anti-icing. Furthermore, the ice quickly melted and rolled off immediately after irradiation, which avoids refreezing again. Thus, the prepared coating maintained sustainable photothermal conversion for effective deicing performance. Besides, the prepared coating possessed mechanical durability, excellent corrosion protection and even kept self-cleaning ability at 400 °C. More importantly, the coating shows excellent self-healing property toward both mechanical and chemical damage. The outstanding environmental adaptability can greatly extend its lifespan and meet the long-term service conditions.

Comparison of PAC and MOAH for understanding the carcinogenic and developmental toxicity potential of mineral oils

The carcinogenicity and developmental toxicity of unrefined mineral oil is related to its 3–7 ring polycyclic aromatic compounds (PAC) content. Therefore, refining operations focus on the targeted removal PAC from mineral oil that may contain aromatics of low toxicological concern. There are thus, two types of aromatic substances in mineral oil: hazardous and non-hazardous. The first type consists of 3–7 ring PAC which may be naked (unsubstituted) or lowly alkylated. The second type or non-hazardous consists of 1–7 ring aromatics with high degree of alkylation or lack of bay or fjord regions. Although these are toxicologically different, they may both elute in the same fraction when using chromatography. To understand how these two aromatic types are related we have assessed the entire mineral oil refinement process by measuring total mineral oil aromatic hydrocarbons (MOAH) content by chromatography next to regulatory hazard tests which focus on 3–7 ring PAC. MOAH content is positively correlated to its molecular weight resulting in aromatic content bias for high viscosity substances. Hazard to 3–7 ring PAC is best controlled by the validated IP346 or modified Ames test. We explain the concept of high vs low alkylation by shortly reviewing new data on alkylated PAC.

Study on the co-carbonization behavior of high-temperature coal tar pitch and raffinate oil of low-temperature coal tar

In needle coke industry, the raffinate oil from raw material refining could be used for co-carbonization to improve the structural evolution of aromatic feedstock with high aromaticity and low alkyl side chain content. High-temperature coal tar pitch (HCTP) and raffinate oil obtained from low-temperature coal tar (LCT) were used to prepare needle coke by liquid phase carbonization, and the characteristics of carbonization behavior as well as the structural evolution of blended materials were also investigated. The raffinate oil possessed abundant saturated compositions and the aromatic component distribution mainly concentrated in 1–3 cyclic aromatic hydrocarbons which resulted in a low yield of derived products and the carbonaceous sheets with poor planarity. Raffinate oil provided sufficient small molecular volatiles of alkyl radicals and generated abundant active sites for the polycondensation of HCTP with high aromaticity and low alkyl side chain content during co-carbonization. The addition of raffinate oil in HCTP facilitated the elimination of steric hindrance and healed the structural defects within the planar aromatic lamellae. This paper improved the utilization of raw material refining treatment and optimized the industrial structure of the needle coke preparation process.

Impact of acid activated Bentonites on foster swelling capacity and sorption dynamics of hydrocarbons, phenol and water

The successful protonation of the dissociable 𝐻 + from different organic acids (with varying alkyl chains) to supplant sodium ions in the inter layers of bentonites resulting in increased surface area has been carried out. The resultant materials were characterized using foster swelling and adsorption capacity techniques. Results show that the foster capacities of acid activated bentonites were greater than the un-activated bentonite (UAB) upon interaction with petroleum hydrocarbons. The bentonite activated with the organic acid having the most alkyl chain, hexanoic acid activated bentonite (HAAB) showed high affinity for all petroleum hydrocarbons. This demonstrates the hydrophilicity of UAB and upon activation, the hydrophobic properties of HAAB. The adsorption capacity result records that bentonites and HAAB adsorbed more petroleum hydrocarbon solvents than other lower alkyl chain acid activated bentonites and UAB. This study shows that HAAB is an excellent adsorbent for the removal of hydrocarbons from industrial wastes.&#x0D; Keywords: Acid Activated Bentonite, Foster Swelling, Adsorption Capacity, Organic Acids, Phenol

Optimization of Poly (vinyl chloride) Surface Modification with an Aromatic Schiff Base-Ni (II) Complex as Photostabilizer

Though PVC is one of the most common synthetic polymers that differ from their analogues in low molecular weight alkyl halides in that they do not readily demonstrate the effects of simple nucleation. Chlorine removal is preferred in many condensation reaction situations, and the creation of the following double bond guarantees dark colored products. The chemical adaptation of poly (vinyl chloride) (PVC) with new functional thiol compound has been reported. A homogenous blend has been inserted to nickel chloride; the polymeric film were exposed to ultraviolet light for 300 hours. The structural changes in the modified film were observed by FTIR spectroscopy and losing in weight; the morphology of surface has been examined by optical microscope.

Effects of Exotic Spartina alterniflora Invasion on Soil Phosphorus and Carbon Pools and Associated Soil Microbial Community Composition in Coastal Wetlands.

Soil microorganisms can be altered by plant invasion into wetland ecosystems and comprise an important linkage between phosphorus (P) availability and soil carbon (C) chemistry; however, the intrinsic mechanisms of P and C transformation associated with microbial community and function are poorly understood in coastal wetland. In this study, we used a sequential fractionation method and 13C nuclear magnetic resonance (NMR) spectroscopy to capture the changes in soil P pools and C chemical composition with bare flats (BF), native Phragmites australis(PA), and invasive Spartina alterniflora(SA), respectively. The responses of the soil microbial community using phospholipid fatty acid (PLFA) profiling and function indicated by nine enzyme activities associated with C, nitrogen (N), and P cycles were also investigated. Compared to PA and BF, SA invasion significantly (P < 0.05) changed P pools and mainly increased the available P by 17.5 and 37.0%, respectively. The presence of the plants (SA and PA) significantly (P < 0.05) altered the soil C chemical composition mainly by affecting the aliphatic functional groups, resulting in a lower alkyl C/O-alkyl C ratio value. Compared to BF and SA, PA significantly (P < 0.05) increased arbuscular mycorrhizal fungi (AMF) abundance. Soil enzyme activity, especially for the P and C cycle enzymes, was also affected by plant species with the highest geometric mean enzyme and hydrolase activity for the PA zone. We also found that soil C compositions and P pools were associated with microbial community structure and enzyme activity, respectively. However, little interaction between C and P was found on either soil microbial composition or soil enzyme activity variation. Further, microbial community composition was tightly correlated with the soil P compared to soil C chemistry, while enzyme activity showed more response with soil C chemistry compared to soil P pool changes.

Investigation on the inhibition mechanism of alkyl diammonium as montmorillonite swelling inhibitor: Experimental and molecular dynamics simulations

Effective inhibition of mud shale hydration and swelling is the major challenge for water-based drilling fluids (WBDFs). In this paper, a series of novel low molecular weight alkyl diammoniums with different alkyl chain lengths was synthesized and evaluated as montmorillonite swelling inhibitor. The inhibition behavior of alkyl diammonium was studied by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), cation exchange capacity (CEC), and molecular dynamics simulation. The XRD results illustrated that the inhibitors (Gs-9, Gs-10, Gs-11, Gs-12, Gs-13 and Gs-14) rapidly lowered the basal spacing (d001 value) of hydrated sodium montmorillonite (Na-Mt) from 1.92 nm to 1.41 nm, which indicates that a flat monolayer of inhibitors was inserted into the interlamination of Na-Mt. The XPS and CEC results showed that the alkyl diammonium displaced exchangeable cations in the interlamination of Na-Mt. The SEM results showed that the alkyl diammonium effectively improved the surface structure and curled edges of hydrated Na-Mt. The simulated results showed that the quaternary ammonium functional groups were fixed firmly on the six- oxygen rings of Na-Mt. The adsorption energy of alkyl diammonium increased with the increase in alkyl chain length. Therefore, alkyl diammonium with long alkyl chain can decrease the amount of inhibitor adsorbed on Na-Mt, thus reducing the dosage of inhibitor used in the WBDFs. This is conducive to reducing drilling costs. Therefore, this research on the inhibition behavior of alkyl diammonium with different hydrophobic chain lengths has important reference value for the development of WBDFs and suitable inhibitors for them.

Characteristics and potential source areas of aliphatic amines in PM2.5 in Yangzhou, China

As highly hydrophilic basic compounds, amines are an important part of the earth's nitrogen cycle and closely related to human health. In this study, a few major low molecular weight alkyl aminium species, including methylaminium (MA), dimethylaminium (DMA) and ethylaminium (EA) in Yangzhou urban aerosols from April to November 2016 were measured and their mean concentrations in aerosols were determined to be 1.418 ± 1.341, 3.623 ± 3.941 and 12.576 ± 10.446 ng/m3, respectively, with higher concentrations in Spring. The total mass percentage of three aminium species to water-soluble organic nitrogen (WSON) were 0.01–5.74% and fraction of EA was highest (0.01–5.02%). The air mass trajectory and potential source contribution analyses indicate that the source of amines in Yangzhou aerosols was mainly from oceans and surrounding provinces, while the Yangtze River Delta region itself had relative little contribution.

Long chain lipid hydroperoxides increase the glutathione redox potential through glutathione peroxidase 4

BackgroundPeroxidation of PUFAs by a variety of endogenous and xenobiotic electrophiles is a recognized pathophysiological process that can lead to adverse health effects. Although secondary products generated from peroxidized PUFAs have been relatively well studied, the role of primary lipid hydroperoxides in mediating early intracellular oxidative events is not well understood. MethodsLive cell imaging was used to monitor changes in glutathione (GSH) oxidation in HAEC expressing the fluorogenic sensor roGFP during exposure to 9-hydroperoxy-10E,12Z-octadecadienoic acid (9-HpODE), a biologically important long chain lipid hydroperoxide, and its secondary product 9-hydroxy-10E,12Z-octadecadienoic acid (9-HODE). The role of hydrogen peroxide (H2O2) was examined by direct measurement and through catalase interventions. shRNA-mediated knockdown of glutathione peroxidase 4 (GPx4) was utilized to determine its involvement in the relay through which 9-HpODE initiates the oxidation of GSH. ResultsExposure to 9-HpODE caused a dose-dependent increase in GSH oxidation in HAEC that was independent of intracellular or extracellular H2O2 production and was exacerbated by NADPH depletion. GPx4 was involved in the initiation of GSH oxidation in HAEC by 9-HpODE, but not that induced by exposure to H2O2 or the low molecular weight alkyl tert-butyl hydroperoxide (TBH). ConclusionsLong chain lipid hydroperoxides can directly alter cytosolic EGSH independent of secondary lipid oxidation products or H2O2 production. NADPH has a protective role against 9-HpODE induced EGSH changes. GPx4 is involved specifically in the reduction of long-chain lipid hydroperoxides, leading to GSH oxidation. SignificanceThese results reveal a previously unrecognized consequence of lipid peroxidation, which may provide insight into disease states involving lipid peroxidation in their pathogenesis.