Ring Structure Research Articles

Collective dynamics of liquid sulphur across the polymerisation transition temperature probed by inelastic x-ray scattering

Inelastic x-ray scattering (IXS) experiments on liquid sulphur were carried out below (140 ∘C) and above (180 ∘C) the polymerisation temperature T λ of about 159 ∘C to investigate changes in the collective dynamics of this unique liquid, that exhibits a liquid–liquid transition. As reported earlier, broad longitudinal acoustic excitation signals were observed at both temperatures, and only the width of the quasielastic peaks slightly decreased when the temperature crossed the transition temperature. A model analysis was performed using a generalised Langevin formalism with a memory function having one thermal and two viscoelastic decay channels with the help of simple sparse modelling, and large positive deviations from the hydrodynamic sound velocity by 51%–54% were observed. The fast viscoelastic relaxation time τ µ is close to the correlation times of intermolecular stretching and bending motions of local sulphur connections in both ring and chain structures, and is similar to those of other molecular liquids. The small contrasts in the IXS spectra across the λ transition result in large changes in only the slow viscoelastic decay time τ α of the memory function. The τ α value at 140 ∘C matches the mixed internal/external torsional modes of S8 molecules well, whereas that at 180 ∘C has no corresponding molecular motion mode. The kinematic viscosity values at the Q→0 limit are much smaller than the minimum values of macroscopic shear viscosity, indicating that large changes in relaxation dynamics are expected with Q in the GHz and MHz excitation regimes.

Enhancing the permeability and selectivity of graphene oxide membrane through polyhedral oligomeric silsesquioxane intercalation for textile wastewater treatment

Graphene oxide-based loose nanofiltration membranes have shown significant potential in nanofiltration processes due to their unique 2D mass transfer nanochannels. However, they still suffer from poor structural stability and overly compact laminar stacking. To address these issues, a novel AP-POSS was intercalated into GO-based membrane to construct a tuned interlayer structure and mass transfer characteristics. The aromatic ring structure of aminophenyl groups on AP-POSS act as hydrophobic side walls of the mass transfer channels between adjacent GO nanosheets, reducing the interaction between water molecules and channel structure. With an optimal amount of AP-POSS as an intercalator, the permeation flux of the prepared POSS-GO membrane could be improved by 30 wt% while maintaining nearly complete rejection of Congo Red (CR). Moreover, the prepared membrane exhibited enhanced structural stability, long-term stability, and a separation factor above 91.0 for CR/NaCl in binary solutions. Our study highlights the excellent performance of the POSS-GO membrane and demonstrates its potential application in dye/salt wastewater treatment.

Sulfonic Acid-Functionalized Tetraphenylethylene-Amplified Electrochemiluminescence by Regulating π-π Interaction.

The electrochemiluminescence (ECL) effectiveness of the tris(bipyridine) ruthenium(II) (Ru(bpy)32+) system is hampered by aggregation-caused quenching (ACQ) in optoelectronic systems as a result of π-π accumulation of the aromatic ring structure. In this work, a negatively charged tetraphenylvinyl molecule (TPE-2SO3Na, TPE-4SO3Na) was synthesized to modify the electrode interface, and the π-π accumulation between Ru(bpy)32+ molecules was transformed into the π-π interaction between Ru(bpy)32+ and TPE molecules. Interestingly, the ECL signal intensity of the Ru(bpy)32+-tripropylamine (TPA) system in the presence of TPE-2SO3Na was increased by about 15 times due to the π-π action and electrostatic action. In comparison with traditional physical packaging with porous zeolites, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs), the fabricated electrode interface modification strategy was simple and efficient to avoid π-π accumulation in aqueous solutions. Our success will inspire other researchers to investigate the supramolecular interaction (π-π interaction, electrostatic interaction, hydrophilic interaction, and host-guest interaction) at the electrode interface to amplify the ECL intensities of Ru(bpy)32+.

An evolved artificial radical cyclase enables the construction of bicyclic terpenoid scaffolds via an H-atom transfer pathway.

While natural terpenoid cyclases generate complex terpenoid structures via cationic mechanisms, alternative radical cyclization pathways are underexplored. The metal-catalysed H-atom transfer reaction (M-HAT) offers an attractive means for hydrofunctionalizing olefins, providing access to terpenoid-like structures. Artificial metalloenzymes offer a promising strategy for introducing M-HAT reactivity into a protein scaffold. Here we report our efforts towards engineering an artificial radical cyclase (ARCase), resulting from anchoring a biotinylated [Co(Schiff-base)] cofactor within an engineered chimeric streptavidin. After two rounds of directed evolution, a double mutant catalyses a radical cyclization to afford bicyclic products with a cis-5-6-fused ring structure and up to 97% enantiomeric excess. The involvement of a histidine ligation to the Co cofactor is confirmed by crystallography. A time course experiment reveals a cascade reaction catalysed by the ARCase, combining a radical cyclization with a conjugate reduction. The ARCase exhibits tolerance towards variations in the dienone substrate, highlighting its potential to access terpenoid scaffolds.

Regulating interfacial structure of fat globules based on milk fat globule membrane with milk phospholipids to improve physicochemical properties and fat digestion of infant formula emulsions

Modulation of a suitable proportion of milk fat globule membrane (MFGM) and milk phospholipid (MPL) at the lipid droplet interface could be an effective strategy to improve the physicochemical properties and digestibility of infant formula emulsion (FE) systems that contain milk protein. The results showed that the distribution of lipid droplets became more uniform, and the adsorption of MFGM and MPL with different thicknesses was observed at the interface by adding different ratios of MFGM and MPL. Meantime, the stability of the FE was significantly increased than FE prepared by only protein-coated oil core, especially FE4 prepared by adding MFGM and MPL (1:3, w/w) as membrane components, the emulsifying activity index (48.28 m2/g) and emulsion stability index (73.08 min) reached the maximum. The emulsion prepared by phospholipid (PL) encapsulation oil core (FE5) exhibited lipid droplet aggregation and poor emulsion dispersion. The results of lipid digestion indicated that FE obtained with MFGM and MPL encapsulated lipid droplets maintained more PL ring structure similar to human milk structure during gastric digestion, which in turn promotes intestinal digestion of lipids by preventing the formation of protein aggregation. At the end of intestinal digestion, FE4 exhibited the highest lipolysis rate (86.48%) and release of free fatty acids (92.05 μmol/mL). Overall, the addition of a suitable ratio of MFGM to MPL, especially MFGM/MPL (1:3, w/w), contributes to the creation of a thin PL interface structure similar to that of human milk. This could facilitate fat degradation and fatty acid release by regulating the lipid droplet interface.

Correction to the article Hopf ring structure on the mod p cohomology of symmetric groups

Correction to the article Hopf ring structure on the mod p cohomology of symmetric groups

Roles and mechanisms of circular RNA in respiratory system cancers.

Circular RNAs (circRNAs) constitute a class of endogenous non-coding RNAs (ncRNAs) that lack a 5'-ended cap and 3'-ended poly (A) tail and form a closed ring structure with covalent bonds. Due to its special structure, circRNA is resistant to Exonuclease R (RNaseR), making its distribution in the cytoplasm quite rich. Advanced high-throughput sequencing and bioinformatics methods have revealed that circRNA is highly conserved, stable, and disease- and tissue-specific. Furthermore, increasing research has confirmed that circRNA, as a driver or suppressor, regulates cancer onset and progression by modulating a series of pathophysiological mechanisms. As a result, circRNA has emerged as a clinical biomarker and therapeutic intervention target. This article reviews the biological functions and regulatory mechanisms of circRNA in the context of respiratory cancer onset and progression.

Chemistry of Cyclo[18]Carbon (C18): A Review.

Carbon-based allotropes are propelling a technological revolution in communication, sensing, and computing, concurrently challenging fundamental theories of the previous century. Nevertheless, the demand for advanced carbon-based materials remains substantial. The crux lies in the efficient and reliable engineering of novel carbon allotrope. Although C18 has undergone theoretical and experimental investigation for an extended period, its preparation and direct observation in the condensed phase occurred only recently through STM/AFM techniques. The distinctive cyclic ring structure and the dual 18-center π delocalization character introduce various uncommon properties to C18, rendering it a subject worthy of in-depth exploration. In this context, this review delves into past developments contributing to the state-of-the-art understanding of C18 and provides insights into how future endeavours can expedite practical applications. Encompassing a broad spectrum, this review comprehensively investigates almost all facets of C18, including geometric characteristics, electron delocalization, bonding nature, aromaticity, reactivity, electronic excitation, UV/Vis spectrum, intermolecular interaction, response to external fields, electron affinity, ionization, and other molecular properties. Moreover, the review also outlines representative strategies for the direct synthesis and characterization of C18 using atom manipulation techniques. Following this, C18-based complexes are summarized, and potential applications in catalysis, electrochemical devices, optoelectronics, and sensing are discussed.

Ultra-sensitive, graphene metasurface sensor integrated with the nonradiative anapole mode for detecting and differentiating two preservatives

Abstract Graphene-based metamaterial sensors are of significant research value for detecting food preservatives at low concentrations due to their extremely high sensitivity levels. In this work, we proposed and experimentally demonstrated an anapole resonance-based graphene metasurface (An-graphene-Ms) sensor with its conductivity altered by electrostatic doping effects for detecting and differentiating between two preservatives, sodium benzoate and potassium sorbate, in the terahertz region. Sodium benzoate, owing to its benzene ring structure, established π–π stacking interactions between the π-electrons in the benzene ring and those in graphene, amplifying the sensing effect. The amplitude changes and phase differences of the An-graphene-Ms sensor for the sodium benzoate detection were greater than those for potassium sorbate at the same concentration. Additionally, to reveal the dependence of the resonance frequency on the time delay, the measured signals were investigated using the continuous wavelet transform (CWT), and the time-frequency combination of the metasurface sensor was performed. The 2D wavelet coefficient intensity cards are effectively constructed through CWT, which also presents a more accurate approach for distinguishing and determining the concentrations of the two preservatives.

Non-adiabatic dynamics of photoexcited cyclobutanone: Predicting structural measurements from trajectory surface hopping with XMS-CASPT2 simulations.

Over the years, theoretical calculations and scalable computer simulations have complemented ultrafast experiments, as they offer the advantage of overcoming experimental restrictions and having access to the whole dynamics. This synergy between theory and experiment promises to yield a deeper understanding of photochemical processes, offering valuable insights into the behavior of complex systems at the molecular level. However, the ability of theoretical models to predict ultrafast experimental outcomes has remained largely unexplored. In this work, we aim to predict the electron diffraction signals of an upcoming ultrafast photochemical experiment using high-level electronic structure calculations and non-adiabatic dynamics simulations. In particular, we perform trajectory surface hopping with extended multi-state complete active space with second order perturbation simulations for understanding the photodissociation of cyclobutanone (CB) upon excitation at 200nm. Spin-orbit couplings are considered for investigating the role of triplet states. Our simulations capture the bond cleavage after ultrafast relaxation from the 3s Rydberg state, leading to the formation of the previously observed primary photoproducts: CO + cyclopropane/propene (C3 products), ketene, and ethene (C2 products). The ratio of the C3:C2 products is found to be about 1:1. Within 700fs, the majority of trajectories transition to their electronic ground state, with a small fraction conserving the initial cyclobutanone ring structure. We found a minimal influence of triplet states during the early stages of the dynamics, with their significance increasing at later times. We simulate MeV-ultrafast electron diffraction (UED) patterns from our trajectory results, linking the observed features with specific photoproducts and the underlying structural dynamics. Our analysis reveals highly intense features in the UED signals corresponding to the photochemical processes of CB. These features offer valuable insights into the experimental monitoring of ring opening dynamics and the formation of C3 and C2 photoproducts.

Ambient hydrogenation of solid aromatics enabled by a high entropy alloy nanocatalyst

Hydrogenation is a versatile chemical process with significant applications in various industries, including food production, petrochemical refining, pharmaceuticals, and hydrogen carriers/safety. Traditional hydrogenation of aromatics, hindered by the stable π-conjugated phenyl ring structures, typically requires high temperatures and pressures, making ambient hydrogenation a grand challenge. Herein, we introduce a PdPtRuCuNi high entropy alloy (HEA) nanocatalyst, achieving an exceptional 100% hydrogenation of carbon-carbon unsaturated bonds, including alkynyl and phenyl groups, in solid 1,4-bis(phenylethynyl)benzene (DEB) at 25 °C under ≤1 bar H2 and solventless condition. This results in a threefold higher hydrogen uptake for DEB-contained composites compared to conventional Pd catalysts, which can only hydrogenate the alkynyl groups with a ~ 27% conversion of DEB. Our experimental results, complemented by theoretical calculations, reveal that PdPtRu alloy is highly active and crucial in enabling the hydrogenation of phenyl groups, while all five elements work synergistically to regulate the reaction rate. Remarkably, this newly developed catalyst also achieves nearly 100% reactivity for ambient hydrogenation of a broad range of aromatics, suggesting its universal effectiveness. Our research uncovers a novel material platform and catalyst design principle for efficient and general hydrogenation. The multi-element synergy in HEA also promises unique catalytic behaviors beyond hydrogenation applications.

Spectroscopic Characterization and Photochemistry of the Atmospherically Relevant Methanesulfenic Acid.

Methanesulfenic acid, CH3SOH, is a fleeting intermediate in the ·OH-initiated oxidation reactions of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) in the atmosphere. Herein, we report the characterization and photochemistry of CH3SOH in Ar- and N2-matrices at 10 K. The characterization of CH3SOH with matrix-isolation IR and UV-vis spectroscopy is supported by D and 13C isotope labeling experiments and quantum chemical calculations. In line with the observed absorption at 260 nm for CH3SOH, its photolysis at 254 nm leads to dissociation by yielding the novel water complex H2CS···H2O, which exhibits a five-membered ring structure with intermolecular S···HO and CH···O hydrogen bonding interactions. Upon further irradiation at 193 nm, the H2CS···H2O complex undergoes dehydrogenation to form CS···H2O, which can further convert to HC(O)SH under irradiation at 254 nm. When the photolysis of CH3SOH was performed in an O2-doped Ar-matrix, methanesulfonic acid (MSA, CH3SO3H) was obtained as the oxidation product.

Synthesis of 6/5/3-Fused Tricyclic Scaffolds via Multistep Cascade Cyclization of α-Aryl Vinylsulfoniums with para-Quinamines and para-Quinols.

Herein, we present a straightforward approach to access hydroindoline-5-one-based 6/5/3-fused polycyclic ring structures through multistep cascade reactions involving α-aryl vinylsulfoniums and para-quinamines. The reactions proceed smoothly under mild conditions to deliver the desired products in generally good isolated yields. This protocol is also applicable to the cascade cycloaddition reactions of α-aryl vinylsulfoniums and para-quinols, effectively generating complex tricyclic scaffolds. In addition, the scale-up synthesis and further derivatizations demonstrate the potential synthetic application of the protocol.

Preparation of 6-Amino-N-hydroxyhexanamide-Modified Porous Chelating Resin for Adsorption of Heavy Metal Ions.

The pollution of water bodies by heavy metal ions has recently become a global concern. In this experiment, a novel chelating resin, D851-6-AHHA, was synthesized by grafting 6-amino-N-hydroxyhexanamide (6-AHHA) onto the (-CH2N-(CH2COOH)2) group of the D851 resin, which contained a hydroxamic acid group, amide group, and some carboxyl groups. This resin was developed for the purpose of removing heavy metal ions, such as Cr(III) and Pb(II), from water. The findings from static adsorption experiments demonstrated the remarkable adsorption effectiveness of D851-6-AHHA resin towards Cr(III) and Pb(II). Specifically, the maximum adsorption capacities for Cr(III) and Pb(II) were determined to be 91.50 mg/g and 611.92 mg/g, respectively. Furthermore, the adsorption kinetics of heavy metal ions by D851-6-AHHA resin followed the quasi-second-order kinetic model, while the adsorption isotherms followed the Langmuir model. These findings suggest that the adsorption process was characterized by monolayer chemisorption. The adsorption mechanism of D851-6-AHHA resin was comprehensively investigated through SEM, XRD, FT-IR, and XPS analyses, revealing a high efficiency of D851-6-AHHA resin in adsorbing Cr(III) and Pb(II). Specifically, the (-C(=O)NHOH) group exhibited a notable affinity for Cr(III) and Pb(II), forming stable multi-elemental ring structures with them. Additionally, dynamic adsorption experiments conducted using fixed-bed setups further validated the effectiveness of D851-6-AHHA resin in removing heavy metal ions from aqueous solutions. In conclusion, the experimental findings underscored the efficacy of D851-6-AHHA resin as a highly efficient adsorbent for remediating water bodies contaminated by heavy metal ions.

Initial pyrolysis of perhydroacenaphthene conformers: A multi-scale simulation and experimental analysis

The enduring quest for a fuel that embodies both high density and superior heat sink capacity has been a long-standing goal within the scientific community. Perhydroacenaphthene (PHAN) fuels, characterized by five-membered ring structure that enhances density, also serve as hydrogen donors to inhibit coking, showcasing significant potential in fuel applications. Given their "strain-free" cyclic configuration, PHAN fuels manifest diverse conformations like chair, boat, and twist, among others, each influencing fuel properties and subsequently affecting pyrolysis process and the utilization of heat sink. In this work, leveraging the five preferred PHAN conformers substantiated by experiments, we embarked on a comprehensive investigation into their microstructures, properties, pyrolysis behavior, and initial pyrolysis mechanisms combining with molecular simulation and experimental analysis. Among them, interaction region indicator (IRI) analysis was employed to elucidate the differences in density. Upon this foundation, taking trans-trans-trans and cis-cis-cis PHAN with minimum and maximum density as models, the effects of different conformations on the initial pyrolysis reaction were explored by micro-pyrolysis system attached to an online GC-MS/FID strategy. It was found that compared to the trans-trans-trans conformation, the cis-cis-cis conformation manifested superior initial pyrolysis activity and more substantial heat sink capacity. Moreover, upon delving into the reaction mechanism and microkinetic analysis, it became evident that the favored initial reaction type of PHAN pyrolysis was H-abstraction reaction, and cis-cis-cis PHAN presented a lower barrier and a faster reaction rate than trans-trans-trans. Additionally, in conjunction with the calculation of free energy barrier and reaction heat of numerous reactions, the kinetic and thermodynamic dominances for the initial pyrolysis pathways of trans-trans-trans and cis-cis-cis PHAN were identified. Finally, utilizing intermolecular interaction energy (ΔE), independent gradient model based on Hirshfeld partition (IGMH) and Xiamen energy decomposition analysis (XEDA), the microscale justification for cis-cis-cis PHAN conformation displaying superior initial pyrolysis activity was further unveiled. This endeavors pioneer innovative pathways for the directional development and application of PHAN conformers.

Influence of age on pelvic inlet and outlet radiographic views

Background. Unstable fractures of the posterior pelvic ring represent a pressing concern in trauma surgery. Minimally invasive osteosynthesis techniques have gained widespread acceptance in contemporary practice. Accurate radiographic visualization is a critical component for the precise and successful placement of iliosacral and transsacral screws. Obtaining and accurately interpreting X-ray images can pose challenges in specific clinical situations, particularly those involving age-related skeletal changes. The aim of the study is to assess the influence of the patient’s age on the measures of pelvic radiographic inlet and outlet views angles for performing a sacral fracture fixation using cannulated screws. Methods. A retrospective analysis of CT data was conducted on 106 patients with posterior pelvic ring injuries requiring cannulated screw fixation. Preoperative CT scans were reconstructed into sagittal projections. We performed construction and measurement of the true inlet angle, super-inlet angle, pelvic outlet angle, sacral concavity angle, promontory angle, S1 and S2 outlet view angles. Statistical correlation between sacral tilt angle and the patient’s age was assessed. Results. A two-step cluster analysis divided the patient cohort into two groups with significant differences in pelvic outlet angles and age (N1 = 64, N2 = 42). Statistically significant differences were found between the two clusters in all the studied parameters: median values of true pelvic inlet angles were 27.2° [23.2-32.2] and 18.2° [11.4-26.6] respectively (p0.001); super-inlet angles were 42.5° [39.3-47.8] and 36.2° [28.7-42.8] respectively (p0.001); promontory angles were 128.1° [123.3-133.2] and 122.1° [115.6-129.3] respectively (p = 0.003); pelvic outlet angles were 62.6° [58.4-69.6] and 50.3° [45.9-53.5] respectively (p0.001); S1 outlet angles were 51.8° [48.9-56.5] and 46.8° [43.1-50.2] respectively (p0.001); S2 outlet angles were 40.8° [37.3-44.6] and 35.7° [30.9-38.6] respectively (p0.001); the mean of the sacral concavity angles was 174.8°±10.5 and 152.1°±38.2 respectively (p0.001); and the main age was 41.6±18.7 and 69.2±16.1 years respectively (p0.001). A statistically significant inverse correlation between age and pelvic tilt angle (ρ = 0.534; p0.001) was found. A novel diagnostic method for identifying sacral dysmorphism using angle measurement within the S1 bone corridor is presented. The sacrum was considered dysmorphic if the angle was equal to or less than 5°. Conclusions. As the patient’s age increases by one year, pelvic outlet angle decreases by 26°. If pelvic inlet angles are equal to or less than 14.45°, the difficulties in visualizing S1 and S2 outlet views during surgery are to be expected. The median of angles difference before and after anterior sacral tilt correction using a coccyx pad was 9.4° with interquartile range from 7.8° to 11°. Significant anatomical variations in posterior pelvic ring structure were observed among the study cohort. Preoperative CT sagittal reconstructions allow appropriate planning of intraoperative visualization considering expected intraoperative radiographic inlet and outlet views.

Mechanisms of interface electrostatic potential induced asphalt-aggregate adhesion

The electrostatic potential at the interface of the asphalt molecular and aggregate oxides is the primary factor generating the adhesion between the asphalt-aggregate contact surfaces. However, the route of electrostatic potential affecting the asphalt-aggregate adhesion is yet to be determined at the molecular level. This study proposed that the electron accumulation at the interface of the asphalt molecular and aggregate oxides generates a significant electrostatic potential hence to induce the adhesion between the asphalt and aggregate in asphalt pavement. A microscopic molecular dynamics (MD) simulation incorporated with macroscopic adhesion work experiments is conducted to analyze the interface adhesive performance between the asphalt and aggregate. The adhesion work experiment demonstrated the effect of aggregate surface oxides on asphalt adhesion at the macro level and further verified the simulation results. The result demonstrated that a notable electron accumulation can be observed by MD at the interface of asphalt molecular and multiple oxides which generates the electrostatic potential. The strong electrostatic attractions and hydrogen bonds between alkaline oxides (MgO, CaO, CaCO3) and asphalt molecules enhance the relative concentration distribution, diffusion coefficient, and adhesion of asphalt on the aggregate surface. The significant electrostatic potential difference at the interface of the asphalt molecular and the oxide enables a strong adhesion between them due to the near-surface failure potential. Besides, the negative charge accumulation on both the benzene ring structure and oxygen atoms in the asphalt molecules results in poor adhesion at the interface of asphalt molecules and multiple oxides. It was found that a high correlation exists between the MD prediction and experimental testing results. Thus, this research provides a valuable tool for guiding the pairing and selection of asphalt with various minerals for pavement design, construction, and maintenance agencies.

Evolution and generation mechanism of retained oil in lacustrine shales: A combined ReaxFF-MD and pyrolysis simulation perspective

To accurately investigate the evolution characteristics and generation mechanism of retained oil, the study analyzed organic-rich lacustrine shale samples from the Paleogene Kongdian Formation in Cangdong Sag, Bohai Bay Basin. This analysis involves Rock-Eval pyrolysis, pyrolysis simulation experiments, Gas Chromatograph Mass Spectrometer (GC–MS), and reactive molecular dynamics simulations (ReaxFF). The results revealed the retained oil primarily consisted of n-alkanes with carbon numbers ranging from C14 to C36. The generation of retained oil occurred through three stages. A slow growth stage of production rate was observed before reaching the peak of oil production in Stage I. Stage II involved a rapid increase in oil retention, with C12–C17 and C24–C32 serving as the primary components, increasing continuously during the pyrolysis process. The generation process involved the cleavage of weak bonds, including bridging bonds (hydroxyl, oxy, peroxy, imino, amino, and nitro), ether bonds, and acid amides in the first stage (Ro =0.50%–0.75%). The carbon chains in aromatic ring structures with heteroatomic functional groups breaks in the second stage (Ro =0.75%–1.20%). In the third stage (Ro =1.20%–2.50%), the ring structures underwent ring-opening reactions to synthesize iso-short-chain olefins and radicals, while further breakdown of aliphatic chains occurred. By coupling pyrolysis simulation experiments and molecular simulation technology, the evolution characteristics and bond breaking mechanism of retained oil in three stages were revealed, providing a reference for the formation and evolution mechanism of retained oil.

Microstructure and properties of SiC ceramic-modified aluminium alloy fabricated using wire arc additive manufacturing

A method for improving the properties of the deposited metal in wire arc additive manufacturing of Al–Si alloy is proposed here, which introduces SiC ceramic particles into the side-axis wire feed. The effects of SiC ceramic particles on the macroscopic morphology, microstructure and mechanical properties, corrosion resistance, and wear resistance of deposited metals were studied. The results show that the introduction of SiC particles will not affect the surface-forming quality of the deposited metal; this is likely due to the stable droplet transfer and no splashing. The transverse and longitudinal tensile strengths are increased by 10.1 % and 11.3 %, respectively, while the corresponding elongations are increased by 33.1 % and 47.2 %, respectively. Further, the corrosion resistance and wear resistance of Al–Si alloy deposited metals containing SiC are improved. The (100) base surface has strong texture characteristics along the deposition direction X0, and the maximum polar density decreases to 13.63, which indicates that SiC promotes the transformation of columnar crystals to equiaxial crystals. The interface between SiC and Al is non-coherent, and the performance improvement lies in the enhanced dispersion distribution and load transfer of SiC. A ring structure was prepared using double-wire arc additive manufacturing technology, and the feasibility of side-axis wire feeding technology was verified.

Lignin: A multifunctional and sustainable photothermal material for solar-driven thermoelectric generation and desalination

The abundant aromatic ring structure and a large number of oxygen-containing functional groups in the lignin offer the possibility of achieving excellent photothermal conversion ability and modulating the synthesis of metal nanoparticles. Herein, three kinds of the lignin with different functional group content were employed to investigate the potential influence on the particle size and the solution stability of the CuS through two reaction pathways. The result of various characterizations indicated that the higher the oxygen-containing functional group content (4.83 mmol/g) of lignin, the smaller the size of CuS nanoparticles (∼80 nm) in solution. And the smaller and homogeneously dispersed CuS offered a higher surface temperature for the solar-driven heat-generating materials. The regulation mechanism was also proposed based on the result of the molecular dynamics simulation and DFT calculation. Subsequently, the photothermal film (Route2 DTAL-PVA-30) and solar-driven aerogel evaporator (Route2 DTAL-AG3) were successfully prepared using the lignin-guided stabilization solution of CuS nanoparticles. The photothermal conversion efficiency of 49.43 % and the equilibrium voltage of 266 mV can be achieved by the Route2 DTAL-PVA-30 under 1 sun using a thermoelectric generator. The Route2 DTAL-AG3 exhibited promising salt-rejecting property and outstanding acid and alkali resistance performance, reaching an evaporation rate of up to 1.93 kg/(m2 h) in the 3.5 wt% seawater under 1sun. This work may provide a novel strategy to realize the regulatory role of lignin in the metal synthesis and achieve the high value-added applications of the lignin.