Formation Of Carboxylic Acids Research Articles

Unlocking the potential of zwitterionic vapor-induced phase separation membranes synthesized from maleic anhydride in polyvinylidene fluoride-based systems for antifouling applications

This work presents an approach to form zwitterionic porous poly(vinylidene fluoride) (PVDF) membranes fabricated by vapor-induced phase separation (VIPS). The reaction between maleic anhydride groups, incorporated initially in the casting solution by blending styrene maleic anhydride (SMA), with 3-((3-aminopropyl)dimethylammonio)propane-1-sulfonate led to the desired zwitterionic moieties. XPS and FTIR analyses confirm the functionalization of the membrane. SEM analyses revealed that it did not have any major impact on the membrane morphology deemed to be close to bicontinuous. While the mean pore size of the virgin membrane was 0.57 μm, it increased to 0.85 μm suggesting the pore-forming effect of SMA during the phase-inversion process. Hydration was significantly enhanced, attributed to the zwitterionic groups on the one hand, but also to the formation of carboxylic acid and amide groups following the ring-opening reaction. It led to significant resistance to bacterial attachment as tested with 4 strains of bacteria including Escherichia coli, Stenotrophomonas maltophilia, Staphylococcus aureus and Streptococcus mutans (>99 % reduction for each). Applied in cyclic water/bacterial solution filtration tests, the modified membrane showed clear improvement in overall performances. Hence, for the virgin membrane, the initial water permeability, flux recovery ratio after the first cycle and flux recovery ratio after the second cycle were found to be 3000 L m−2 h−1.bar−1, 12 % and 53 %, respectively. For the optimized zwitterionic membrane, they were measured to be 7000 L m−2 h−1.bar−1, 26 % and 100 %, respectively. The efficacy of styrene maleic anhydride as a precursor for achieving stable and efficient zwitterionization of PVDF microfiltration membranes is evidenced, rendering it valuable for the filtration of microorganism-containing wastewater. Moreover, its potential application extends to the biomedical realm.

Macrocyclic Porphyrin Photocatalysts without Metal Chelation: A Novel Pathway for Complete Degradation of Tough Halophenols with Longwave Visible LED Light Source

Halophenols are toxic and persistent pollutants in water environments which poses harm to various organisms. Due to their high stability and long residence time, ultraviolet radiation, heavy metals and oxidizing agents have been largely adopted on treating these compounds. However, these treatment methods could pose toxicity or hazardous risks to the marine environment and plant operators. In this study, a water-soluble porphyrin photocatalyst was synthesized and introduced for halophenol treatment using UV-free LED white light. The porphyrin catalyst is a macrocyclic ring consisting of pyrroles linked with methine bridges, the highly conjugated ring provided the superior functionality of visible light absorption. Surprisingly, over 99% degradation of halophenols and over 90% dehalogenation have been achieved without metal chelation, even higher than those of transition metal porphyrins with inclusion of Fe3+, Zn2+, Cu2+, Co2+, Ni2+, and Mn2+. Ring-opening reactions were confirmed with the formation of carboxylic acids; dicarboxylic acids like acrylic acid, and malonic acid; while fumaric acid was the main product. Total organic carbon results indicated no CO2 produced during the reaction. Triplet absorbance and scavenger studies also indicated that singlet oxygen and conduction band electrons are the main radical species for halophenol degradation. The 100-fold singlet emission quenching over triplet absorption quenching indicated that the excited electrons tend to be transferred via singlet state. This concept brings along new approaches detoxifying halophenol-related wastewater without UV, metals and other additives, which is more environmentally-friendly and sheds light to the conversion of toxic materials into useful chemical precursors.

Advances in plastic mycoremediation: Focus on the isoenzymes of the lignin degradation complex

This study investigates P. ostreatus and A. bisporus biodegradation capacity of low density polyethylene (LDPE) oxidised to simulate environmental weathering. Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were used to analyse the degradation of LDPE treated with fungal cultures. Molecular implications of LDPE degradation by P. ostreatus and A. bisporus were evaluated by Reverse transcription followed by quantitative PCR (qRT-PCR) of lac, mnp and lip genes expression. After 90 days of incubation, FT-IR analysis showed, for both fungal treatments, an increasing in the intensity of peaks related to the asymmetric C-C-O stretching (1160 to 1000 cm−1) and the -OH stretching (3700 to 3200 cm−1) due to the formation of alcohols and carboxylic acid, indicating depolymerisation of LDPE. This was confirmed by the SEM analysis, where a widespread alteration of the surface morphology was observed for treated LDPE fragments. Results revealed that the exposure of P. ostreatus to oxidised LDPE treatment led to a significant increase in the expression of the lac6, lac7, lac9, lac10 and mnp2 genes, while A. bisporus showed an over-expression in lac2 and lac12 genes. The obtained results offer new perspectives for a biotechnological use of P. ostreatus and A. bisporus for plastic bioremediation.

Thermal oxidation mechanism of palmitic aicd

The oxidation and degradation of fats lead to a decrease in the nutritional value of food and pose safety concerns. Saturated fatty acids also hold a significant position in the field of lipid oxidation. In this study, the oxidation products of methyl palmitate were investigated by using gas chromatography mass spectrometry (GC–MS). Seven monohydroperoxides and 72 secondary oxidation products were detected. Combined with density functional theory (DFT) calculations, the formation mechanisms of oxidation products can be summarized into four stages. The initial stage involved the formation of monohydroperoxides and alkanes, followed by the subsequent stage involving methyl x-oxo(hydroxy)hexadecanoates. The third stage involved the formation of methyl ketones, carboxylic acids, and aldehydes, while the final stage involved lactones. Meanwhile, methyl ketones were the most abundant oxidation product, approximately 25 times more abundant than aldehydes; the calculated results agreed well with the experimental results. The establishment of a comprehensive thermal oxidation mechanism for palmitic acid provided a new foundation for future lipid oxidation analyses.

Gas chromatography-mass spectrometry characterization of the aroma of Ossetian cheeses

The aim of the study was the qualitative and quantitative determination of volatile aroma compounds and their formation pathways in brine Ossetian cheeses. Volatile components of cheeses were isolated by steam distillation and extraction with dichloromethane, with their subsequent determination and quantification by gas chromatography-mass spectrometry. The results of the analysis are presented according to the structural classes of the main chemical components and the corresponding microbial metabolic processes. Four processes were found to be the main contributors to flavor formation: lipolysis, proteolysis, glycolysis, and a number of oxidative enzymatic transformations. Lipolysis of the fatty fraction of cheeses is a source of formation of volatile carboxylic acids and their esters. Proteolysis of the casein fraction yields branched alcohols, aldehydes, and a number of aromatic and heteroaromatic compounds. Glycolysis of the carbohydrate fraction is a source of ethanol formation, which is the main cause of the dominance of ethyl esters in the ester fraction. Redox enzymatic transformations mainly determine the biosynthesis of unbranched aldehydes, ketones and lactones. A clear distinction between retail and homemade cheeses was observed, due to the different technological approaches to the cheese preparation. The structuralchemical and quantitative evolution of the volatile composition of the studied cheese samples during ripening is tentatively shown. From the authors’ point of view, the aromatic composition of the Tib cheese sort is the most consistent with the Ossetian cheese standard. This study represents the first gas chromatographic study of Ossetian cheeses and aims to create objective criteria for controlling technological processes and product quality during production and storage in the food industry.

Unveiling the effect of Pt addition on Ag/C catalyst for enhanced glycerol electrooxidation

This study investigates the performance of Ag/C and a range of Ag100-xPtx/C nanoparticles as electrocatalysts for glycerol electrooxidation reaction (GEOR). Low amounts of Pt (<2 %) were spontaneously deposited on Ag-supported nanoparticles using Ag as a sacrificial metal. The primary aim of the study is to determine the impact of adding a small amount of Pt to the Ag/C catalyst. Cyclic voltammetry is employed to assess the electrocatalyst's performance, while in situ Fourier Transform Infrared (FTIR) spectroscopy is used to examine the formed reaction intermediates and products. Additionally, physical characterization techniques such as XRD and XPS are applied to analyze the material structure. The Ag100-xPtx/C series of catalysts show a significant improvement in the glycerol oxidation process with the addition of 0.25 % of Pt to the material composition compared to pure Ag. It is observed that the enhancement performance reaches a limit at a Pt composition of approximately 7 % in the metallic nanoparticles, indicating that further increases in Pt content do not yield additional improvements. The in situ FTIR studies reveal that the presence of Pt on the Ag surface leads to a distinct glycerol electrooxidation mechanism compared to using Ag alone. Small amounts of Pt deposits promote C−C−C bond breaking, as evidenced by the selective formation of formic acid and CO2. FTIR results demonstrate a preference for carboxylic acid formation, with no significant evidence of dihydroxyacetone (DHA) production. The findings emphasize the critical role of Pt composition in the electrooxidation of glycerol paving the way for the design and development of more efficient and sustainable electrooxidation catalysts.

Comparison of electrochemical advanced oxidation processes for the treatment of complex synthetic dye mixtures

Many industries use complex synthetic organic dye mixtures in their dyeing processes, producing wastewater effluents with complex dye mixtures. In this study, electrochemical advanced oxidation processes like electrochemical oxidation (ECO), ECO with electrogenerated H2O2 (ECO-H2O2), electro-Fenton (EF), and photo electro-Fenton (PEF) with UVC irradiation were compared to discolor and mineralize a mixture of Methyl Orange, Methyl Red, and Toluidine Blue O with a boron-doped diamond anode and a gas-diffusion cathode. While ECO and ECO-H2O2 required long times to achieve a complete discoloration, the dyes were quickly degraded by EF and PEF due to the oxidation with ∙OH formed from Fenton’s reaction. Almost complete mineralization was rapidly achieved by PEF for a solution with 424 mg O2 L−1 of chemical oxygen demand (COD) at a current density of 66.6 mA cm−2 due to the synergistic action of the UVC irradiation. Additionally, the treated effluent was evaluated using the DFZ (Deutsche Farb Zah) parameter for water condition, offering a new perspective and distinguishing this work from previous studies focused on electrified technologies for dye removal. The same behavior has been found for the mixture of such dyes in an industrial effluent upon PEF treatment, even showing faster discoloration and COD reduction as result of the additional removal with active chlorine formed from Cl− oxidation. Ion-exclusion HPLC analysis of the treated synthetic effluent revealed the formation of final carboxylic acids like malic, acetic, oxalic, and formic. Released nitrate, ammonia, and nitrite were detected as nitrogenated by-products from the initial N of the dyes.

Insights into the metabolism of CH-PIATA - a novel synthetic cannabinoid featuring an acetamide linker.

The recent change from the popular carboxamide to an acetamide (ATA) linker scaffold in synthetic cannabinoid receptor agonists (SCRAs) can be interpreted as an attempt to circumvent legal regulations, setting new analytical challenges. Metabolites of N-cyclohexyl-2-(1-pentyl-1H-indol-3-yl)acetamide: CH-PIATA, the second ATA type SCRA detected in the EU, were investigated in urine and serum samples by LC-HRMS-MS and LC-MS-MS. Two different in vitro models: a pHLM assay and HepG2-cells as well as an in silico prediction by GLORYx freeware assisted in metabolite formation/identification. CH-PIATA was extensively metabolized, leading to metabolites formed primarily by mono- and dihydroxylation. For urine and serum specimens, monohydroxylation at the indole core or the methylene spacer of the acetamide linker (M1.8), carboxylic acid formation at the N-pentyl side chain (M3.1), and degradation of the latter leading to a tentatively identified N-propionic acid metabolite (M5.1) are suggested as reliable markers for substance intake. The N-propionic acid metabolite could not be confirmed in the in vitro assays as it includes multiple consecutive metabolic reactions. Furthermore, CH-PIATA could be detected as parent substance in blood samples, but not in urine. Both in vitro assays and the in silico tool proved suitable for predicting metabolites of CH-PIATA. Considering effort and costs, pHLM incubations seem to be more effective for metabolite prediction in forensic toxicology. The highlighted phase I metabolites serve as reliable urinary targets for confirming CH-PIATA use. The in silico approach is advantageous when reference material is unavailable.

Strain-induced carbon-carbon bond cleavage of bowl-shaped sumanenone.

This study details a highly effective ring-opening reaction that involves acid-mediated carbon-carbon bond cleavage of the buckybowl, sumanenone. The reaction of the bowl-shaped sumanenone with AcOH and TfOH results in the formation of a planar carboxylic acid. The examination of reactivity in comparison to planar analogues, along with theoretical calculations, suggests that the release of curved strain is a crucial factor for the success of this reaction.

Changes in the Composition of the Dried Asian Lacquer (Korean Lacquer) Film Irradiated with Ultraviolet Light

Asian lacquer is a material that has been used in Asia from ancient times to coat the surface of objects. It is a durable material, but is known to be weak to ultraviolet light (UV). Here, to understand the deterioration characteristics of Asian lacquer due to UV, the changes were analyzed using ultraviolet photometry, IR, and pyrolysis/GC/MS (pyrolysis/GC/MS), after exposing the lacquer coating film to UV (&lt;i&gt;λ&lt;/i&gt;= 340 nm). In the ultraviolet photometry, the surface exposed to UV showed fluorescence. In IR analysis, the powder sample showed little change after exposure to UV, but on the surface, C = O groups increased, while C―H groups decreased significantly. Analysis with pyrolysis/GC/MS revealed that the composition of organic acid increased significantly. Carboxylic acids having 9 or less carbon atoms and dicarboxylic acids were significantly increased compared to carboxylic acid having 16 carbon atoms. In addition, urushiol with the oxidized side chain was also increased. This shows that the penetration depth of UV is the limiting factor for deterioration, and that the deterioration of lacquer due to UV proceeds with the destruction of carbon–carbon single and double bonds and the subsequent formation of carboxylic acid.

Degradation behavior and ageing mechanism of E-glass fiber reinforced epoxy resin composite pipes under accelerated thermal ageing conditions

In this work, accelerated ageing experiments with circulating air and simulated oilfield water were carried out at 95 °C on aromatic amine-cured GFRP pipes used in oilfield environments, with effective ageing times of 5000 h and 3000 h respectively. The differences in ageing behavior and ageing mechanisms of the GFRP tubes at different times under the two conditions were then analyzed and discussed. The changes in the apparent morphology and microstructure of the samples after thermal ageing were first observed using optical microscopy and scanning electron microscopy, and the results demonstrated that the thermal oxygen environment triggered more drastic color changes and obvious oxidation layers. The resin matrix manifests a large number of nano-scale micropores and modest matrix shrinkage pores in the micron size range, this is accompanied by damage to the fiber cross-section. Hydrothermal ageing causes further dissolution of the surface resin and dissolution of the exposed fibers. ATR-FTIR analysis verifies the increase in CO bonding of the ester group during thermal oxidation and the decreasing strength of the C–O–C and C–H bonds, while the behavior of ageing water absorption and glass fiber hydrolysis is illustrated by changes in the intensity of the –OH and Si–O characteristic bands. NMR hydrogen spectroscopy verified the formation of amides, methyl ethers and carboxylic acids in the thermal oxidation products of epoxy resins. Furthermore, the decay pattern of the circumferential tensile strength indicates that the hydrothermal environment has a more significant effect on the mechanical properties of GFRP pipes, which is attributed to the physical dissolution of the surface resin, significant hydrolytic damage to the surface exposed fibers, and the combined damage to the resin-fiber interfacial bonding by chloride ions in simulated oilfield water.

Electrochemical Hydro- and Deuterocarboxylation of Allenes

AbstractElectrochemical hydrocarboxylation and deuterocarboxylation of allenes and carbon dioxide were achieved with H2O and D2O, respectively. This reaction generally affords good to excellent regioselectivity in the formation of diverse carboxylic acids.

Photocatalytic degradation of polyethylene and polystyrene microplastics by α-Fe2O3/g-C3N4.

This study investigated the photodegradation of microplastics (MPs) by α-Fe2O3/g-C3N4. The effects of α-Fe2O3/g-C3N4 on MPs' surface were investigated through various techniques. With the addition of α-Fe2O3/g-C3N4 and under visible light irradiation, cracks and folds were observed on the MP films and particles. Compared to the treatment without photocatalyst addition, the mass loss of MPs increased with irradiation time when α-Fe2O3/g-C3N4 was added. Specifically, polystyrene films and particles in water showed 9.94% and 7.81% increased mass loss, respectively. The degradation of MPs using α-Fe2O3/g-C3N4 demonstrated the behavior consistent with the pseudo-first-order kinetic model. The presence of α-Fe2O3/g-C3N4 led to an increase in surface oxygen-containing functional groups and crystallinity while decreasing the average molecular weight of MPs. After 30days of irradiation, the characteristic tensile bands of MPs with α-Fe2O3/g-C3N4 significantly increased, and the detection of carboxyl bands indicated the formation of carboxylic acid, ketones, and lactones as degradation products.

Nontrivial Impact of Relative Humidity on Organic New Particle Formation from Ozonolysis of cis-3-Hexenyl Acetate

The impact of relative humidity (RH) on organic new particle formation (NPF) from the ozonolysis of biogenic volatile organic compounds (BVOCs) remains an area of active debate. Previous reports provide contradictory results, indicating both the depression and enhancement of NPF under conditions of high RH. Herein, we report on the impact of RH on NPF from the dark ozonolysis of cis-3-hexenyl acetate (CHA), a green-leaf volatile (GLV) emitted by vegetation. We show that RH inhibits NPF by this BVOC, essentially shutting it down at RH levels &gt; 1%. While the mechanism for the inhibition of NPF remains unclear, we demonstrate that it is likely not due to increased losses of CHA to the humid chamber walls. New oxidation products dominant under humid conditions are proposed that, based on estimated vapor pressures (VPs), should enhance NPF; however, it is possible that the vapor phase concentration of these low-volatility products is not sufficient to initiate NPF. Furthermore, the reaction of C3-excited state Criegee intermediates (CIs) with water may lead to the formation of small carboxylic acids that do not contribute to NPF. This hypothesis is supported by experiments with quaternary O3 + CHA + α-pinene + RH systems, which showed decreases in total α-pinene-derived NPF at ~0% RH and subsequent recovery at elevated RH.

The Metabolic Profile of the Synthetic Cannabinoid Receptor Agonist ADB-HEXINACA using Human Hepatocytes, LC-QTOF-MS and Synthesized Reference Standards.

Synthetic cannabinoid receptor agonists (SCRAs) remain a major public health concern, with their use implicated in intoxications and drug-related deaths worldwide. Increasing our systematic understanding of SCRA metabolism supports clinical and forensic toxicology casework, facilitating the timely identification of analytical targets for toxicological screening procedures and confirmatory analysis. This is particularly important as new SCRAs continue to emerge on the illicit drug market. In this work, the metabolism of ADB-HEXINACA (ADB-HINACA, N-[1-amino-3,3-dimethyl-1-oxobutan-2-yl]-1-hexyl-1H-indazole-3-carboxamide), which has increased in prevalence in the United Kingdom and other jurisdictions, was investigated using in vitro techniques. The (S)-enantiomer of ADB-HEXINACA was incubated with pooled human hepatocytes (HHeps) over three hours, to identify unique and abundant metabolites using liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). In total, 16 metabolites were identified, resulting from mono-hydroxylation, di-hydroxylation, ketone formation (mono-hydroxylation then dehydrogenation), carboxylic acid formation, terminal amide hydrolysis, dihydrodiol formation, glucuronidation, and combinations thereof. The majority of metabolism took place on the hexyl tail, forming ketone and mono-hydroxylated products. The major metabolite was the 5-oxo-hexyl product (M9), whilst the most significant mono-hydroxylation product was the 4-hydroxy-hexyl product (M8), both of which were confirmed by comparison to in-house synthesized reference standards. The 5-hydroxy-hexyl (M6) and 6-hydroxy-hexyl (M7) metabolites were not chromatographically resolved and the 5-hydroxy-hexyl product was the second largest mono-hydroxylated metabolite. The structures of the terminal amide hydrolysis products without (M16, third largest metabolite) and with the 5-positioned ketone (M13) were also confirmed by comparison to synthesized reference standards, along with the 4-oxo-hexyl metabolite (M11). The 5-oxo-hexyl and 4-hydroxy-hexyl metabolites are suggested as biomarkers for ADB-HEXINACA consumption.

Improving the sorption properties of mesoporous carbons for the removal of cobalt, nickel and manganese from spent lithium-ion batteries effluent

The competitive sorption of Co2+, Li+, Ni2+, and Mn2+, strategic metals from spent lithium-ion batteries and their leachates, was studied using activated mesoporous carbons. The mesoporous carbon was synthesized by the replica method using silica gel as a template and exhibited a high surface area with an accessible pore volume due to mesopores (Vmeso > 95%). Fast kinetics and high sorption capacities of these metals were achieved with the chemical activation of mesoporous carbons. The surface modification of the mesoporous carbon was carried out by physical activation with O2 at 450 °C and chemical activation under mild conditions (room temperatures) with NaClO2/H2O2 as oxidizing agents. FTIR analysis and conductimetric titration showed that the combination of an initial physical activation step, followed by chemical functionalization, maximized the formation of carboxylic acids (from 0.2 to 0.9 meq/g), due to the complete oxidation of the weakly acidic groups. Those carbons were tested in sorption experiments of the lithium-ion battery metals in monometallic solutions, where physically activated and chemically reactivated mesoporous carbon selectively removed over 80% of Co2+, Ni2+, and Mn2+, with sorption capacities over 20 mg/g, while only 20% of Li+ was removed. This carbon stood out amongst the others studied (2 to 11-fold increase in sorption capacities depending on the metal) and was tested in multimetallic solutions, showing fast removal rates, reaching equilibrium within the first 15 min, as well as selectivity towards divalent cations (18 mg/g of Co2+) with insignificant lithium sorption (qLi = 0.33 mg/g). Desorption of metals was carried out using H2SO4, which allowed the recovery and twofold of the initial concentrations of Co, Ni, and Mn.

General and specialized metabolites in peanut roots regulate arbuscular mycorrhizal symbiosis

Arbuscular mycorrhizae (AM) fungi form symbiotic associations with plant roots, providing nutritional benefits and promoting plant growth and defenses against various stresses. Metabolic changes in the roots during AM fungal colonization are key to understanding the development and maintenance of such symbioses. Here, we investigated metabolic changes in the roots of peanut (Arachis hypogaea L.) plants during the colonization and development of AM symbiosis and compared to uncolonized roots. The primary changes during the initial stage of AM colonization were in the content and composition of phenylpropanoid and flavonoid compounds. These compounds function in signaling pathways that regulate recognitions, interactions, and pre-colonization between roots and AM fungi. Flavonoid compounds decreased by 25% when the symbiosis was fully established compared to the initial colonization. After AM symbiosis was established, general metabolism strongly shifted toward the formation of lipids, amino acids, carboxylic acids, and carbohydrates. Lipid compounds increased by 8.5% from the pre-symbiotic stage to well-established symbiosis. Lyso-phosphatidylcholines, which are signaling compounds, were only present in AM roots, and decreased in content after the symbiosis was established. In the initial stage of AM establishment, the content of salicylic acid increased two-fold, whereas jasmonic acid and abscisic acid decreased compared to uncolonized roots. Jasmonic acid content decreased in roots after the symbiosis was well established. AM symbiosis was associated with high levels of calcium, magnesium, and D-(+)-mannose, which stimulated seedling growth. Overall, specific metabolites that favored establishment of AM symbiosis were common in the roots primarily during early colonization, whereas general metabolism was strongly altered when AM symbiosis was well-established. In conclusion, specialized metabolites functioned as signaling compounds to establish AM symbiosis. These compounds were no longer produced after the symbiosis between the roots and AM had been fully established.

Ionizing radiation as a pretreatment technique on the valorization of rice straw

ABSTRACT The current study focuses on investigating the efficacy of gamma radiation exposure as a pretreatment technique on the valorization of rice straw using advanced analytical pyrolysis technology. The results obtained shed light on the impact of gamma radiation on the composition of functional groups within the rice straw. Specifically, the weaker C-H and C-O bonds appear to be affected, leading to slight modifications in their composition. Furthermore, the crystallinity of the sample experiences minor changes, indicating some level of structural disruption caused by radiation exposure. To delve deeper into the effects of gamma radiation on the rice straw, fast pyrolysis is performed on both the exposed and raw samples. Notably, the exposed samples demonstrate a substantial increase in the formation of carboxylic acids during the pyrolysis process. This finding suggests that exposure to gamma radiation influences the chemical reactions occurring within the rice straw, leading to the production of a higher yield of carboxylic acids compared to the unexposed samples. A tentative reaction pathway leading to the formation of different products is visualized and presented in the study. The changes in functional group composition, the minor disruption in crystallinity, and the increased formation of carboxylic acids collectively indicate the transformative effects of gamma radiation on the rice straw samples.

Effect of silane coupling agent on the ultraviolet weathering behavior of polylactic acid based composites

Polylactic acid (PLA) is a promising material due to its biodegradability and compatibility. However, the limited resistance to ultraviolet (UV) degradation of PLA composites hinders their use in automotive interior materials. In our previous work, we successfully prepared 3D printed filaments by combining KH550-treated micro-nano rice husk (MNRH) fibers with KH570-treated PLA, which exhibited favorable performance. This study aimed to investigate the effects of silane coupling agents, MNRH, and accelerated UV weathering time on the photodegradation behavior of 3D printed PLA-matrix composites reinforced with MNRH. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) were utilized to characterize the 3D printed PLA-matrix composites. Furthermore, an exponential equation between tensile strength and UV weathering time was established, providing theoretical guidance for predicting the service life of automotive interior materials based on PLA composites. The morphological characterization experimental results indicate that with prolonged UV aging time, both PLA and RH6-KH550/KH570 composite materials transitioned from transparency to translucency. This transition can be attributed to the rupture of polylactic acid molecular chains and chemical bonds during the UV aging process. FTIR test results revealed the formation of carboxylic acid in the composite, and the reduction of C = O absorption intensity indicated that MNRH and silane coupling agents exhibited a stabilizing effect on the UV durability of the RH6-KH550/KH570 composite. TGA and DSC results indicated that KH550 and KH570 delayed the photodegradation rate of PLA-matrix composites.

Micro-impact-induced mechano-chemical synthesis of organic precursors from FeC/FeN and carbonates/nitrates in water and its extension to nucleobases

Abstract Much effort was taken to elucidate how organic precursors appeared in early Earth, and attention was paid to two impact experiments: hypervelocity impacts by a propellant gun which simulated meteorite collides to Earth forming fatty acids and amino acids from inorganics, and micro-impacts by a planetary ball-mill which formed ammonium and acetic acid from inorganics. Our extended study on micro-impacts showed the formation of carboxylic acids, amines, and amino acids from Fe3C/Fe4N, carbon, and carbonates/nitrates by milling up to 30 h at 40 G. Fe(CO2)2·2H2O accelerated the formation a step further. Cu addition caused superior capability to form amines and amino acids. Two reaction fields were disclosed. In the impact field, the hydration of ferrous materials generated hydrogen which hydrogenated inorganic carbons to organics and ferrous transient materials and, in the maturing field, hydrogenated materials were then transformed into complex organics. Iron and CO2 were presumably the key components in the Hadean Ocean. Discussions on the mechano-chemical reaction were extended to serpentinization coupled with diastrophism of oceanic crusts and further led to a depiction that organic precursors were formed by micro-impacts and frictions of rocks and sands (like milling-balls) due to tremors in crusts. It provides a new path on how organic precursors were formed on the aqua-planet Earth.