查找使用阿拉丁产品的科研文献

A Mechanistic Study of Methanol-to-Aromatics Reaction over Ga-Modified ZSM-5 Zeolites: Understanding the Dehydrogenation Process

Pan Gao,Jun Xu,Guodong Qi,Chao Wang,Qiang Wang,Yanxi Zhao,Yuhua Zhang,Ningdong Feng,Xingling Zhao,Jinlin Li,Feng Deng

The methanol-to-aromatics (MTA) reaction was investigated on Ga-modified ZSM-5 zeolites (Ga/ZSM-5). As revealed by 71Ga and 1H solid-state NMR and FT-IR of pyridine adsorption measurements, cationic Ga species are formed as Lewis acid sites by substitution of Brønsted acid sites on H-ZSM-5. Further experimental studies show that C5- and C6-cycloalkenes are generated during the MTA reaction, which lead to the formation of cyclic carbocations as precursors to aromatics. Isotope exchange experiments demonstrate that the reactivity of the cyclic carbocations on Ga/ZSM-5 is much higher than that on H-ZSM-5 and they play an intermediate role in the formation of aromatics. In addition to the traditional bimolecular hydrogen transfer (HT) reaction, the dehydrogenation of alkenes with the release of H2 (DeaH2 process) was identified to significantly contribute to the formation of aromatics. The transformation of cycloalkenes to aromatics is favored by promotion of the DeaH2 process and competes with the HT route on Ga/ZSM-5, while these cycloalkenes tend to crack back to alkenes, and the dominating HT route results in lower aromatic selectivity on H-ZSM-5. A DeaH2-aromatization route mediated by the cooperation of cationic Ga species and Brønsted acid sites was proposed for the enhanced formation of aromatics on Ga/ZSM-5 zeolite.

Mechanistic study on the enhanced N2 selectivity for NH3 selective oxidation over Pt-encapsulated cu-ZSM-5 catalysts

Weixiang Chen,Yuxiong Wang,Yaoyu Zhang,Yue Liu,Zhongbiao Wu

Ammonia (NH 3 ) has emerged as a promising zero‑carbon energy source for energy and transportation. However, its utilization leads to the emission of NH 3 , which contributes to PM 2.5 formation and disrupts the global nitrogen cycle. Selective catalytic oxidation (SCO) represents a mainstream technology for NH 3 treatment, yet achieving both sufficient activity and high N 2 selectivity across a broad temperature window remains challenging. Here, a core-shell Pt@Cu-ZSM-5 catalyst was employed for NH 3 catalytic abatement by encapsulating metallic Pt clusters (Pt 0 ) inside the channels of Cu ion-exchanged ZSM-5. The optimal sample achieved a complete NH 3 conversion below 250 °C and maintained over 92% N 2 selectivity from 250 to 500 °C due to the synergism between the Pt Cu dual sites. Mechanistic studies revealed that NH 3 oxidation preferentially occurred on Pt 0 sites with excellent redox capacity to produce N 2 O and NO x at relatively low and high temperatures, respectively. And the presence of Cu ions (Cu δ+ ) could efficiently both inhibit the formation of N 2 O on Pt 0 sites and reduce NO x emission, thereby improving the N 2 selectivity. At relatively low temperatures, NH 3 -solvated Cu + (NH 3 ) 2 could migrate to the adjacent Pt sites and reduce the adsorbed NO* species from NH 3 oxidation, damping the formation of N 2 O. At high temperatures, the NO and NO 2 emitted from Pt 0 sites could be reduced on Cu δ+ sites via a typical selective catalytic reduction. This study provides new insights into the rational design of bifunctional SCO catalysts and offers a comprehensive understanding of the synergistic effects in Pt Cu dual-site systems.

Co-exposure to polystyrene nanoplastics and 3, 3’, 4, 4’, 5-pentachlorobiphenyl induces synergistic toxicity in human sperm

Shenglin Peng,Jianping Huang,Kun Gao,Fengrong Nie,Zhen Peng,Yimin Cheng,Jin Hu

Growing evidence links environmental pollutant exposure to the deterioration of male reproductive health. In this study, the interactive toxicity between polystyrene nanoplastics (PS-NPs) and 3,3′,4,4′,5-pentachlorobiphenyl on human sperm functions were evaluated. Functional assays were performed on sperm in vitro from healthy volunteers treated separately or jointly with PS-NPs and PCB-126. Key endpoints—motility, cervical mucus-penetrating ability, capacitation, acrosome reaction, intracellular reactive oxygen species, and mitochondrial membrane potential—were significantly more impaired under co-exposure conditions than with individual treatments. Notably, combined treatment synergistically increased ROS accumulation, enhanced mitochondrial depolarization, and inhibited progesterone-stimulated capacitation and acrosome reaction of human sperm. The observed synergistic toxicity may be mediated through oxidative stress and disruption of mitochondrial function, leading to apoptotic-like changes. These results draw attention to the reproductive risks that may emerge from dual exposure to nanoplastics and stable organic environmental chemicals within the setting of idiopathic male infertility.

Microwave-Assisted In Situ Encapsulation of Uniform Ag Nanoclusters in ZSM-5 for Enhanced Catalytic and Antibacterial Performance

Liyuan Wang,Zhishun Feng,Shiji Li,Hongsheng Liu,Yanying Ren,Junfeng Gao,Lei Li

Silver nanoparticles hold great promise in biomedical and environmental applications, yet small and uniform Ag nanoclusters are hindered by easy aggregation, uncontrollable growth, and difficult recovery. Here we report a rapid and controllable ultrasmall (1–4.5 nm) Ag nanocluster by uniformly dispersed encapsulation in ZSM-5 channels using a microwave-assisted one-pot synthesis strategy. The ZSM-5 containing 1.21 wt % Ag nanoclusters exhibits a high Ag atomic utilization rate of 81.2%. The unique confinement structure effectively prevents Ag nanocluster overgrowth while conferring exceptional recyclability, maintaining over 99.9% bactericidal efficacy against Escherichia coli after three cycles. Performance testing reveals the material exhibits remarkable peroxidase-like activity (3.73 U/mg) and catalytic capability (methylene blue reduction rate constant of 0.167 min–1). This study offers a size-controllable approach for preparing high-performance, easily recoverable, and scalable Ag-based nanomaterials.

PTPRE promotes gastric cancer cell resistance to 5-fluorouracil by inhibiting ferroptosis via the Src/FAK/TRIB3 axis

Ming Liu,Xiaomei Liao,Fangchao Wang,Pengqing Jiao,Zhongkai Wang

Acquired drug resistance is a major cause of failure in gastric cancer treatment. The protein tyrosine phosphatase receptor type E (PTPRE) plays an oncogenic role in certain tumours; however, its function in chemotherapy-resistant gastric cancer remains unclear. Therefore, we analysed PTPRE expression in gastric cancer using The Cancer Genome Atlas. In vitro experiments were then conducted to investigate the effects of PTPRE on the resistance of cancer cells to 5-fluorouracil (5-FU) and its potential mechanisms. The results were further validated in vitro using xenograft studies. We found that PTPRE is upregulated in gastric cancer tissues and participates in the induction of 5-FU resistance. Mechanistic studies revealed that PTPRE suppressed ferroptosis in gastric cancer cells and promoted 5-FU resistance by activating the Src/FAK pathway to upregulate TRIB3 expression. In summary, PTPRE suppresses ferroptosis in gastric cancer cells via the Src/FAK/TRIB3 signalling pathway, thereby inducing 5-FU resistance. Intervention with PTPRE and its downstream targets may represent a potential approach for the clinical treatment of 5-FU-resistant gastric cancer.

Ultrasensitive Profiling of Arachidonic Acid Metabolites Based on 5-(Diisopropylamino)amylamine Derivatization–Ultraperformance Liquid Chromatography–Tandem Mass Spectrometry

Peiyan Zheng,Xiaowen Huang,Qing Wang,Yida Zhang,Mingtao Liu,Manyun Jiang,Sitong Liu,Huimin Huang,Wenting Luo,Jian-Lin Wu,Baoqing Sun

Arachidonic acid (AA) and its metabolites play critical roles in inflammation and immune regulation, modulating the initiation, amplification, and resolution of inflammation. However, their comprehensive quantification remains a challenging endeavor owing to complex metabolic pathways and biological matrix effects. This study introduces a novel metabolomics method involving 5-(diisopropylamino)amylamine (DIAAA) derivatization coupled with ultraperformance liquid chromatography–tandem mass spectrometry to address these issues. The method demonstrated high sensitivity and specificity, with limits of quantification meeting stringent criteria (relative standard deviation <20%; recovery rate, 85–115%, signal-to-noise ratio >10). It effectively quantified 14 key AA metabolites, including hydroxyeicosatetraenoic acids, prostaglandins, and leukotrienes, across a wide linear range (R2 > 0.98). The results of intra- and interassay precision tests exhibited low coefficients of variation (≤15%), underscoring the reproducibility of the method. DIAAA derivatization also mitigated matrix variability, improving the accuracy of metabolite detection in serum samples. The hallmark of allergic diseases is a disrupted AA metabolism, where elevated specific metabolites (AA, HETEs, LTB4, and PGD2) show strong diagnostic promise, and a unique metabolite signature in polysensitized patients indicates a link to inflammatory severity. This advanced analytical approach offers significant potential for elucidating the role of AA metabolism in allergic diseases and holds promise for applications in clinical diagnostics and therapeutic monitoring.

Assembly of ordered polyaniline-graphene hybrid nanomaterials based on poly(2-methoxyaniline-5-sulfonic acid) functionalized graphene nanosheets

Qiang Zhao,Junhua Chen,Fubin Luo,Lu Shen,Ying Wang,Kun Wu,Mangeng Lu

Nanostructure of ordered polyaniline-graphene (PANI-rGO PMAS ) hybrid nanomaterials is assembled based on poly(2-methoxyaniline-5-sulfonic acid) (PMAS) functionalized reduced graphene oxide (rGO PMAS ) nanosheets. The presence of PMAS not only improves dispersibility of reduced graphene oxide nanosheets, but also plays a key role for heterogeneous nucleation of polyaniline (PANI) nanorods . The formation mechanism of ordered PANI-rGO PMAS hybrid nanomaterials was studied in details by using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and ultraviolet-visible spectrophotometry (UV–vis). The conductivity of PANI-rGO PMAS hybrid with 17   wt% rGO PMAS is as high as 4480   S/m, compared with 2.93   S/m for pure PANI. The cyclic voltammetry tests indicate that, PANI-rGO PMAS containing 2   wt% rGO PMAS possesses fast response to redox reactions and excellent reversible stability. It has a high specific capacitance of 385   F   g −1 at the scan rate of 10   mV   s −1 with potential ranges from −0.2 to 0.8   V. This ordered polyaniline-graphene hybrid has potential applications for flexible supercapacitors, sensors, batteries, electromagnetic materials and thermoelectric materials, etc.

Electrochemical oxidation of guanosine-5′-triphosphate on a graphene and ionic liquid composite modified carbon molecular wire electrode

Wei Sun,Li Xu,Xiuzhen Wang,Jun Liu,Guangjiu Li,Zhenfan Sun

A graphene, chitosan and 1-ethyl-3-methylimidazolium tetrafluoroborate composite was prepared and modified on the surface of a carbon molecular wire electrode. The fabricated electrode was characterized by different methods such as scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy . Electrochemical behaviors of guanosine-5′-triphosphate (GTP) were carefully studied on the modified electrode . The electrochemical parameters such as the charge transfer coefficient ( α ) and the electrode reaction standard rate constant ( k s ) were calculated with the results as 0.57 and 1.56   ×   10 −4   s −1 . Under the optimized conditions, the oxidation peak current was proportion to the GTP concentration in the range from 0.007 to 70.0   μmol/L with the detection limit of 0.232   nmol/L (S/N   =   3). Moreover, the proposed method showed good selectivity to the GTP detection without the interference of coexisting substances, and was further applied to the artificial samples determination with satisfactory results.

Preparation of 2,5-furandicarboxylic acid from carbohydrates via 5-acetoxymethylfurfural as intermediate in a single acetic acid system

Lu Yanyu,Lin Changqu,Yang Hao,Ma Peipei,Chen Jishuang,He Zhuang,Wu Hongli,Cao Fei,Chen Kequan,Ouyang Pingkai

Abstract FDCA (2,5-furandicarboxylic acid), produced by oxidizing carbohydrate-derived HMF (5-hydroxymethylfurfural), is a valuable monomer for biopolymers. The difference in the solvent system between the dehydration reaction and oxidation reactions seriously affects the process continuity and production efficiency. Herein, we reported a cascade process for FDCA production from carbohydrates in a single acetic acid system. The fructose conversion was complete and total furan compounds yield reached nearly 90%, which contained 42.8% HMF and 47.1% 5-acetoxymethylfurfural (AMF) in the acetic acid system with NaBr addition. After the azeotropic distillation and vacuum distillation in situ, AMF, a more stable intermediate than HMF, could be easily collected with 90.5% recovery and 99.9% purity. AMF was also oxidized into FDCA with 91.1% yield by Co/Mn/Br catalysts in the acetic acid system. Finally, the cascade process, including fructose dehydration–esterification and HMF/AMF mixture oxidation, was successfully realized in a single acetic acid system. This process is simple to operate, easy to implement, eliminates the use of extra acid or self-made catalysts and expensive solvents, and has the potential for continuous preparation from carbohydrates to FDCA. Graphical Abstract

Soluplus-stabilized 5-fluorouracil-entrapped niosomal formulations prepared via active and passive loading techniques: comparative physico-chemical evaluation

Onyinyechi Lydia Ugorji,Olisa Ivy Okoye,Chinekwu Nwangwu,Chinazom Precious Agbo,Franklin Chimaobi Kenechukwu

Bifunctional catalyst of CuMn-HZSM-5 for selective catalytic reduction of NO and CO oxidation under oxygen atmosphere

Yangyang Guo,Yang Zheng,Yue Peng,Tao Yue,Tingyu Zhu

Simultaneous removal of NO x and CO from steel sintering has attracted great attention because it is difficult to balance the catalyst reducibility and surface acidity merely using metal oxides or zeolite catalysts. In this study, a mixed CuMn-HZSM-5 catalyst was prepared via an impregnation method. The optimized sample exhibited excellent performance with 90% NO conversion and 100% CO conversion at 175 °C. The activity window of the catalyst was coincident with the actual demand of sintering flue gas control at 150-250℃. The active component CuMn suppressed the excessive Lewis acid sites on the zeolite support for NH 3 adsorption, while the reducibility of the catalyst also decreased compared with that of pure CuMn metal oxides . This synergistic effect was beneficial for the reduction of NH 3 nonselective oxidation with O 2 . In addition, both the DFT and DRIFTS results revealed that NO conversion was improved by CO introduction at low temperature, since NO could adsorb on the CO-preadsorbed sites for the reduction to N 2 via the O atoms of Mn 3c sites, i.e., adsorbed CO could also serve as a reductant to reduce NO to N 2 , which provides another reaction pathway in SCR reactions. Moreover, the NO 2 − and N 2 O 2 − species were observed in the spectra as key intermediates to oxidize CO to CO 2 , which are also the promoters for CO control.

Hierarchical VAPO-5 Catalysts Prepared from Different Vanadium Sources in Fluoride Medium and Their Performance in Toluene Oxidation

Zhang Jian,Ma Yongwei,Shao Hui

Abstract Hierarchical VAPO-5 molecular sieves were prepared with different vanadium resources in the absence/presence of fluorine and characterized by XRD, SEM, N 2 adsorption-desorption, and NH 3 -TPD. The catalytic performances of hierarchical VAPO-5 molecular sieves were evaluated using toluene oxidation as the probe reaction and the corresponding mechanism was further proposed. The sample D-AFI-2(F) synthesized in a fluorine system with NH 4 VO 3 as metal sources show better catalytic performance than other samples in toluene oxidation, which is ascribed to the hierarchically porous structure and more acidic sites. The optimized condition of toluene oxidation was attained at the reaction temperature of 60°C, the reaction time of 5 h, the molar ratio of H 2 O 2 to toluene 2 : 1, the mass ratio of acetonitrile to toluene 6 : 1, and the mass ratio of catalyst to toluene 10%. In this case, the toluene conversion was 21.0%, and the selectivity of benzaldehyde, benzyl alcohol, and cresol was 43.3, 11.4, and 26.2%, respectively.