Search Results (114)

Volatile fingerprint analysis using Gas Chromatography–Ion Mobility Spectrometry (GC-IMS) was applied to differentiate cowhide (22 samples), sheepskin (6 samples), and pigskin (6 samples). A total of 126 signal peaks were detected from the whole GC-IMS dataset, with 96 volatile compounds identified. Principal Component Analysis (PCA) revealed distinct clustering: cowhide exhibited unique volatile profiles, separating itself clearly from sheepskin and pigskin, which showed significant similarity. This was confirmed by Hierarchical clustering, K-means clustering (optimal k = 2), and Partial Least Squares Discriminant Analysis (PLS-DA) (R² = 0.9836, Q² = 0.9040). Cowhide was characterized by exclusive compounds (2-Hexanone, alpha-Thujene, Butyl acetate, 3-Methyl-2-butanol, 2-Heptanone, Hexyl methyl ether-monomer, Diethyl disulfide). Sheepskin and pigskin shared exclusive compounds (2-Methyl propanol, Isobutyl acetate, 2-Pentyl acetate, 3-Penten-2-one, 2,5-Dimethylfuran). Orthogonal PLS-DA (OPLS-DA) further differentiated sheepskin (Ethyl isobutanoate-dimer, Pentyl acetate-dimer, 3-Methyl-2-butanol, 2-Pentanone, 2-Methylbutanol-dimer, 3-Methyl-1-butanol, 2,5-Dimethylfuran, Propan-2-ol, Ethanol-dimer, and alpha-Thujene) and pigskin (Butan-2-one, Pentanal-dimer, 1-Pentanal-monomer, Ethyl vinyl ether, Z-2-Heptene, and Butyronitrile), identifying alpha-Thujene, 3-Methyl-2-butanol, and 2,5-Dimethylfuran as universal discriminatory markers. GC-IMS coupled with chemometric analysis provides a robust approach for leather authentication. Full article

To address the challenges of strong heterogeneity and poor crude oil mobility in tight conglomerate reservoirs of the Mahu Oilfield, this study systematically evaluated the effects of different surfactants on wettability alteration, spontaneous imbibition, and relative permeability through high-temperature/high-pressure spontaneous imbibition experiments, online Nuclear Magnetic Resonance (NMR) monitoring, and relative permeability measurements. Core samples from the Jinlong and Madong areas (porosity: 5.98–17.55%; permeability: 0.005–0.148 mD) were characterized alongside X-Ray Diffraction (XRD) data (clay mineral content: 22–35.7%) to compare the performance of anionic, cationic, nonionic, and biosurfactants. The results indicated that the nonionic surfactant AEO-2 (Fatty Alcohol Polyoxyethylene Ether) (0.2% concentration) at 80 °C exhibited optimal performance, achieving the following results: 1. a reduction in wettability contact angles by 80–90° (transitioning from oil-wet to water-wet); 2. a decrease in interfacial tension to 0.64 mN/m; 3. an imbibition recovery rate of 40.14%—5 to 10 percentage points higher than conventional fracturing fluids. NMR data revealed that nanopores (<50 nm) contributed 75.36% of the total recovery, serving as the primary channels for oil mobilization. Relative permeability tests confirmed that AEO-2 reduced residual oil saturation by 6.21–6.38%, significantly improving fluid flow in highly heterogeneous reservoirs. Mechanistic analysis highlighted that the synergy between wettability reversal and interfacial tension reduction was the key driver of recovery enhancement. This study provides a theoretical foundation and practical solutions for the efficient development of tight conglomerate reservoirs. Full article

Volatile organic compounds (VOCs) are key aroma determinants in pork, and gas chromatography-ion mobility spectrometry (GC-IMS) is an effective technique for their detection. However, the detection conditions for pork using GC-IMS have yet to be standardized. This study employed GC-IMS to investigate the effects of incubation (temperature/duration) and medium (water and different concentrations of NaCl) environments on VOCs in pork. Statistical analyses including t-tests, PLS-DA, and OPLS-DA were employed to assess VOC differences. The results showed that: (1) VOC diversity and intensity increased with incubation temperature and time, with optimal signals obtained at 100 °C for 20 min. (2) The sample medium significantly influenced aroma release. When the medium contained 10% NaCl, the relative content of aldehydes increased, showing that these compounds were optimally released. (3) Under the optimized conditions, 15 key differential VOCs were identified from different muscle tissues, including 10 aldehydes, 2 esters, 1 ketone, 1 alcohol and 1 ether. This work establishes practical GC-IMS parameters for pork VOC analysis and provides a reliable reference for flavor-related studies. Full article

This study investigated the effects of three cooking methods—fragmenting process (FP), boiling treatment (BT), and high-pressure steam (HPS) treatment—on the structure and volatile compounds (VOCs) of fresh Lyophyllum decastes. The surface morphology and functional groups of L. decastes were analyzed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The VOCs in L. decastes were analyzed by comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC-MS) and gas chromatography–ion mobility spectrometry (GC-IMS). SEM results showed that HPS resulted in the most pronounced structural disruption, forming a honeycomb-like porous surface, whereas FP yielded smaller fragments with smoother surfaces. FTIR spectra indicated that none of the treatments significantly altered the characteristic functional groups. A total of 73 VOCs were identified by GC×GC-MS, including 23 hydrocarbons, 14 alcohols, 10 ketones, seven aldehydes, six ethers, three esters, two terpenes, and eight other compounds. Additionally, 22 VOCs were identified by GC-IMS, including seven alcohols, six aldehydes, five esters, three ketones, and one other compound. The four compounds benzaldehyde, benzeneacetaldehyde, (E)-2-hexen-1-ol, and 1-hexanal were detected by both methods. Among the three methods, FP induced the least structural damage and better preserved the VOCs. These results offer theoretical insights and technical support for the flavor-oriented deep processing of L. decastes. Full article

Beiwudu Hulatang, a traditional Chinese culinary delicacy, is valued for its complex flavor profile; however, its characteristic aroma compounds and the determinants of sensory quality remain insufficiently studied. This study evaluated the flavor characteristics of four commercial samples and one laboratory-made sample of Beiwudu Hulatang using gas chromatography–ion mobility spectrometry (GC-IMS), electronic nose (E-nose), electronic tongue (E-tongue), and sensory evaluation. The results of E-tongue analysis indicated that bitterness and saltiness were the dominant taste attributes. E-nose analysis demonstrated strong responses to sulfur-containing compounds, alcohols, and alkanes, indicating their significant contribution to the overall aroma. A total of 60 volatile compounds were identified by GC-IMS, with ethers, alcohols, and terpenes being the most abundant chemical groups. Among these, 13 key aroma compounds were screened as discriminative markers (OAV > 1, VIP > 1) by integrating the odor activity value (OAV) and orthogonal partial least squares-discriminant analysis (OPLS-DA). The Pearson correlation analysis further revealed that sensory attributes, particularly aroma and overall acceptability, were positively correlated with propanal, heptaldehyde, and 1,8-cineol, and negatively correlated with linalool and limonene. Overall, this study provides a systematic characterization of the flavor profile of Beiwudu Hulatang and establishes a scientific basis for its quality standardization and flavor-oriented product development. Full article

The integrated injection of low-salinity water (LSW) and carbon dioxide (CO₂) into the water-alternating-gas (WAG) process offers advantages, primarily increasing oil recovery and reducing operating costs. However, CO₂ has challenges in sweep efficiency due to significant differences in density and viscosity compared with oil. While LSW and dimethyl ether (DME) have shown promise in improving recovery through wettability alteration and reducing minimum miscible pressure, interfacial tension (IFT), and CO₂ mobility, their synergistic integration with CO₂-WAG remains poorly understood. Existing DME-based enhanced oil recovery (EOR) studies have not explored low-salinity water injection as a cost-effective alternative to mitigate high DME operating costs. This study introduces the CO₂/DME-LSWAG method, systematically evaluating the effect of DME concentrations (0%, 10%, 25%) and LSWs (seawater, twice-diluted seawater, ten-times-diluted seawater) on sweep and displacement efficiencies, oil recovery, and CO₂ storage in a 2D cross-sectional carbonate reservoir model. Results showed that DME dramatically reduces IFT (67% and 95% at 10% and 25% DME solvent, respectively) while salinity effects are relatively small. Compared with CO₂-LSWAG, the oil recovery factor improved by 5.2–13.1% depending on DME concentration and water salinity, with DME performance maximized at higher salinity water. CO₂ storage efficiency showed opposing trends. Structural trapping decreased, while solubility trapping increased with lower salinity. The sensitivity analysis identified DME concentration as the dominant factor for CO₂ storage. The composition modeling and simulation of the CO₂/DME-LSWAG process provide critical engineering guidance for the design of future EOR and CO₂ storage projects that utilize DME in carbonate reservoirs. Full article

There are many obstacles to the industrial application of CO₂ hydrogenation reduction technology, the most important of which is the high economic cost. The purpose of this study is to explore the interaction mechanism between the active component CuO-ZnO-Al₂O₃(CZA) and the zeolite carrier Zeolite Socony Mobil-5(ZSM-5), screen the simplified preparation method of catalysts with high catalytic performance, and further promote the industrial application of CO₂ hydrogenation reduction technology. In this study, the effects of the gas velocity of the feedstock, the reaction temperature, the content of acidic sites in the carrier, the filling amount of active component, and the mixing mode of the active component and the carrier on catalytic CO₂ hydrogenation reduction were investigated. The structure of the catalysts was analyzed by X-ray diffractometer (XRD), Brunauer-Emmett-Teller (BET), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The catalyst surface properties were analyzed by X-ray photoelectron spectroscopy (XPS), ammonia temperature programmed desorption (NH₃-TPD), hydrogen temperature programed reduction (H₂-TPR) and other characterization methods. The research found that the grinding treatment led to the insertion of CZA between ZSM-5 zeolite particles in CZA@HZ5-20-GB, which was prepared via grinding both CZA and H-ZSM-5 with an Si/Al ratio of 20, inhibiting the action of strongly acidic sites in the zeolite, resulting in only CO and MeOH in the catalytic products, with no Dimethyl Ether (DME) generation. Full article

Tetrahydroprotoberberine alkaloids (THPBs) are bioactive natural products bearing stereogenic centers that frequently exhibit enantiomer-specific pharmacological effects. Xylopinine (XPN), a representative THPB, shows cytotoxic, antimicrobial, and antimalarial activity in vitro, and displays pronounced stereoselectivity in vivo, with the naturally occurring (S)-enantiomer emphasizing the need for reliable enantioselective analysis. In this study, we present the synthesis of racemic XPN from norlaudanosine, and its first comprehensive cyclodextrin-assisted capillary electrophoresis screening dedicated to the enantioseparation of XPN. Sulfated- and sulfobutyl-ether-β-cyclodextrin (S-β-CyD, SBE-β-CyD) provided efficient resolution (R_s > 3), while heptakis-(6-deoxy-6-(2-carboxyethyl)thio)-β-CyD (subetadex, SBX) yielded outstanding separation (R_s > 9). The enantiomer migration order was consistently R,S, except when using SBE-β-CyD, which showed the inverse sequence. Chiral HPLC using a Chiralpak AD column in polar organic mode with methanol modified with 0.1% diethylamine as mobile phase enabled the semi-preparative isolation of XPN enantiomers, with the (S)-enantiomer exceeding 95% purity. The absolute configuration was confirmed by circular dichroism spectroscopy. ¹H NMR titration and 2D rotating-frame nuclear Overhauser effect correlation spectroscopy (ROESY) consistently revealed multi-site recognition of XPN by SBX, supporting the inclusion of both aromatic rings (A and D). Full article

Optical fiber composite insulators are essential for photoelectric current measurement, yet insulation failure at embedded optical fiber interfaces remains a major challenge to long-term stability. This study proposes a strategy to replace conventional silicone rubber with cycloaliphatic-like epoxy resin (CEP) as the shed-sheathing material. Three optical fibers with distinct outer coatings, ethylene-tetrafluoroethylene copolymer (ETFE), thermoplastic polyester elastomer (TPEE), and epoxy acrylate resin (EA), were evaluated for their interfacial compatibility with CEP. ETFE, with low surface energy and weak polarity, exhibited poor wettability with CEP, resulting in an interfacial tensile strength of 0 MPa, pronounced dye penetration, and rapid electrical tree propagation. Its average interfacial breakdown voltage was only 8 kV, and the interfacial leakage current reached 35 μA after hygrothermal aging. In contrast, TPEE exhibited high surface energy and strong polarity, enabling strong bonding with CEP, yielding an average interfacial tensile strength of approximately 46 MPa. Such a strong interface effectively suppressed electrical tree growth, increased the average interfacial breakdown voltage to 27 kV, and maintained the interfacial leakage current below 5 μA even after hygrothermal aging. EA exhibited moderate interfacial performance. Mechanism analysis revealed that polar ester and ether groups in TPEE enhanced interfacial electrostatic interactions, restricted the mobility of CEP molecular chain segments, and increased charge traps. These synergistic effects suppressed interfacial charge transport and improved insulation strength. This work offers valuable insight into structure–property relationships at fiber–resin interfaces and provides a useful reference for the design of composite insulation materials. Full article

In response to the challenges associated with weld treatment during the on-site corrosion protection of hydraulic steel gates, this paper proposes a method utilizing a magnetic adsorption climbing robot to perform corrosion protection operations. Firstly, a magnetic adsorption climbing robot with a multi-wheel independent drive configuration is proposed as a mobile platform. The robot body consists of six joint modules, with the two middle joints featuring adjustable suspension. The joints are connected in series via an EtherCAT bus communication system. Secondly, the kinematic model of the climbing robot is analyzed and a PID trajectory tracking control method is designed, based on the kinematic model and trajectory deviation information collected by the vision system. Subsequently, the proposed kinematic model and trajectory tracking control method are validated through Python3 simulation and actual operation tests on a curved trajectory, demonstrating the rationality of the designed PID controller and control parameters. Finally, an intelligent software system for weld defect detection based on computer vision is developed. This system is demonstrated to conduct defect detection on images of the current weld position using a trained model. Full article

Pine needles are an industrial feedstock for extracts used in a variety of applications, but conventional extraction methods often result in a degradation of the terpenoid compounds that naturally occur in loblolly pine (Pinus taeda). Separation of these compounds from pine biomass is an energy-intensive operation, typically requiring a significant input of thermal energy. An alternative separation approach with potential energy savings is extraction with a condensable gas, namely, dimethyl ether. Biomass materials are exposed to liquid dimethyl ether under pressure, which mobilizes the organics. The extract is then separated from the insoluble pine matter, and dimethyl ether is volatilized away from the separated organic species. A variety of terpene derivatives were extracted from pine needle biomass using this approach, including monoterpenes, sesquiterpenes, and related oxygenates, which were identified using two-dimensional gas chromatography/mass spectrometry. Additionally, the dimethyl ether-treated needles resemble needles subjected to low-temperature drying, whereas needles treated with a high-temperature drying method appear to have shrunken structures. The results suggest that dimethyl ether extraction has significant potential for separating valuable organics from complex matrices without the application of thermal energy during treatment. Full article

The increasing environmental concerns and regulatory restrictions on toxic conventional solvents have driven the search for sustainable alternatives. Dimethyl isosorbide (DMI), a bio-renewable solvent, has shown potential as a replacement for short-chain glycol ethers, although its use as solvent in liquid chromatography (LC) is underexplored. This study presents a physicochemical characterization of DMI with a particular focus on its application as an innovative solvent in LC analyses. The partition coefficient (log P = −0.44) was determined using the OECD 107 method, and viscosity measurements for DMI and its mixtures with water and ethanol were conducted at 25 °C, 40 °C, and 60 °C. Viscosity ranged from 1.28 mPa·s at 60 °C to 2.62 mPa·s at 40 °C. The Central Composite Face 2³ experimental design for studying the chromatographic behavior of DMI confirmed that 50% (v/v) DMI can be effectively utilized in the mobile phases, at a column temperature of 40 °C, with backpressures ranging from 160 to 300 bar and a UV cut-off at 240 nm. Its effectiveness as an eluent in LC was demonstrated for the quantification of methylparaben and propylparaben in pharmaceutical formulations. This study highlights DMI’s promise as a sustainable bio-renewable alternative to conventional organic solvents used as eluents in LC, supporting eco-friendly practices in pharmaceutical analysis. Full article

The growing energy demand has emphasized the importance of developing nuclear technologies and high-purity lithium isotopes (⁶Li and ⁷Li) as raw materials. This study investigates how voltage and migration time affect two types of low-density polyethylene membranes—one impregnated with ionic liquids and the other non-impregnated—for lithium isotope separation via electromigration from a lithium-loaded organic phase to an aqueous solution. We developed a laboratory-made setup for high-precision lithium isotope measurements (2RSD = ±0.30‰) of natural carbonate samples (LSVEC) and an optimized protocol for isotope ratio measurements using quadrupole ICP-MS with the sample-standard bracketing method (SSB). The results document that both impregnated and non-impregnated membranes can achieve promising ⁶Li enrichment under different environmental conditions, including ionic liquids and organic solutions in the cathode chamber. Lithium-ion mobility is influenced by voltage in an environment assisted by 0.1 mol/L tetrabutylammonium perchlorate and increases quasi-linearly from 5 to 15 V. Between 20 and 25 h, the lithium-ion concentration had the maximum value, after which the trend declined. In the BayesGLM model, we incorporated all data and systematically eliminated those with a low enrichment factor, either individually or in groups. Our findings indicated that the model was not significantly affected by the exclusion of measurements with low α. This suggests that voltage and migration time are crucial, and achieving a better enrichment factor depends on applying the optimal ratio of ionic liquids, crown ethers, and organic solvents. Ionic liquids used for impregnation sustain enrichment in the first hours, particularly for ⁷Li; however, after 25 h, ⁶Li demonstrated a higher enrichment capacity. The maximum single-stage separation factor for ⁶Li/⁷Li was achieved at 24 and 48 h for an impregnated membrane M2 (α = 1.021/1.029) and a non-impregnated membrane M5 (α = 1.031/1.038). Full article

NASICON-type titanium and zirconium phosphates doped with rare-earth cations, A_0.33M₂(PO₄)₃ (M = Ti, Zr; A = Dy, Y, Yb), were synthesized using the sol–gel method and investigated as catalysts for ethanol dehydration at 300–400 °C. The catalysts were characterized via XRD, SEM, BET, and FTIR spectroscopy. The relationships between the catalyst composition, acidity and the dehydration activity were evaluated. Diethyl ether (DEE) formation is promoted by the presence of the zirconium phosphates (ZrP), while the presence of titanium phosphate (TiP) catalyzes the formation of both ethylene and diethyl ether (DEE). The application of Fourier-transform infrared (FTIR) spectroscopy to the analysis of adsorbed C₆H₆ has revealed the presence of hydroxyl groups exhibiting varying degrees of proton-donating mobility. This finding has enabled the correlation of the structure of the active sites with the process’s selectivity. The results underscore the key function of OH-group localization and framework geometry in the control of form-selective reactions. Full article

Poly-ether ether ketone (PEEK) is a high-performance thermoplastic known for its excellent mechanical properties, making it relevant for aerospace and medical applications. Additive manufacturing (AM) represents a critical step towards integrating PEEK into these sectors, particularly for complex geometries and custom parts. However, the mechanical properties achieved through AM have not yet reached those obtained via conventional techniques. Recent studies have sought to optimize the printing parameters to bridge this gap, but their findings remain inconsistent and difficult to generalize—suggesting a strong dependence on the experimental conditions. This is partly due to the Fused Filament Fabrication of PEEK being an emerging technology, with many studies relying on in-house built printers. Moreover, the underlying microstructural mechanisms governing its performance have rarely been explored in depth. In this work, we establish clear processing–structure–property relationships by integrating a rigorous DoE approach with comprehensive microstructural characterization. Our results highlight the dominant role of the processing environment near the glass transition temperature in promoting chain mobility, enhancing the amorphous phase ordering, and improving the mechanical performance: crystallinity alone does not fully explain the mechanical behavior of additively manufactured PEEK. Further, higher nozzle temperatures lower the porosity and increase the filament bonding, while faster printing speeds reduce the crystallinity and increase the porosity, negatively affecting the mechanical integrity. The results of this study are generalizable to any FFF printer of PEEK. Other materials or printing technologies are out of the scope of this work. Full article