查找使用阿拉丁产品的科研文献

A Carbon Catalyst Co-Doped with P and N for Efficient and Selective Oxidation of 5-Hydroxymethylfurfural into 2,5-Diformylfuran

Huifa Zhang,James H. Clark,Tong Geng,Huixian Zhang,Fahai Cao

Graphical A new world for carbon : Phosphorus and nitrogen co-doped carbon (P−C−N) catalyst demonstrates a superb catalytic activity towards selective aerobic oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF). A newly designed N and P co-doped carbon material has been developed to catalyze the conversion of 5-hydroxymethylfurfural (HMF) to 2,5-furandialdehyde (DFF) with unprecedented yield and selectivity and demonstrating a synergistic effect between the heteroatoms. The desired catalyst was first synthesized via a pyrolysis method using urea as the nitrogen and carbon source followed by calcination with phytic acid solution as the phosphorus source. The mass ratio of phytic acid to C 3 N 4 and calcination temperature were varied to investigate their effects on catalyst synthesis and microstructure as well as subsequent catalytic activity in simple reaction systems under oxygen. The effect of reaction conditions on the final HMF conversion and DFF selectivity were also investigated systematically. The P−C−N-5-800 catalyst obtained with the optimized annealing temperature of 800 °C and mass ratio of phytic acid/C 3 N 4 of 5 enabled a 99.5 % DFF yield at 120 °C for 9 h under 10 bar oxygen pressure, being the highest among any reported metal-free heterogeneous catalyst to date. The excellent performance of P−C−N-5-800 could be ascribed to the synergy between N and P heteroatoms as well as the high content of graphitic-N and the P−C species within the carbon structure. Reusability studies show that the P−C−N-5-800 catalyst was stable and reusable without deactivation. These results strongly suggest that P−C−N-5-800 is a promising catalyst for large-scale production of DFF in a green manner.

Purification of (S)-3-cyano-5-methylhexanoic acid from bioconversion broth using an acetone/ammonium sulfate aqueous two-phase system

Zhe-Ming Wu,Chang-Ling Hao,Tao Tong,Ren-Chao Zheng,Yu-Guo Zheng

( S )-3-Cyano-5-methylhexanoic acid (( S )-CMHA) is the key chiral intermediate of pregabalin . In this paper, an aqueous two-phase system (ATPS) was developed to extract ( S )-CMHA from nitrilase-catalyzed bioconversion broth. Inorganic salts and hydrophilic solvents were screened to form ATPS, among which an acetone/ammonium sulfate ATPS was investigated in detail, including phase diagram, effect of phase composition and stability of ( S )-CMHA. The maximum product recovery of 99.15% was obtained by an optimized ATPS system composed of 15% (w/w) ammonium sulfate and 35% (w/w) acetone with the removal of 99% cells and 86.27% proteins. The total ( S )-CMHA yield reached 92.11% after back-extraction. The recycling use of ammonium sulfate was investigated, and 93.10% of salt in the salt-rich phase was recovered with the addition of methanol. The results demonstrated the efficiency of the two-step extraction process for separation of ( S )-CMHA.

5-Aminolevulinic Acid-Loaded Hyaluronic Acid Dissolving Microneedles for Effective Photodynamic Therapy of Superficial Tumors with Enhanced Long-Term Stability

Jinjin Zhu,Liyun Dong,Hongyao Du,Jinzhu Mao,Ying Xie,Hua Wang,Jiajia Lan,Yuchen Lou,Yangxue Fu,Jingjing Wen,Biling Jiang,Yuce Li,Jintao Zhu,Juan Tao

5-Aminolevulinic acid (5-ALA) is one of the most widely used prodrug in clinical photodynamic therapy of dermatological diseases and cancers; yet, its clinical application is still limited by the shallow skin penetration and unsatisfied stability in any existed formulations. Here, 5-ALA-loaded hyaluronic acid dissolving microneedles (5-ALA@HAMNs) are prepared for photodynamic therapy of superficial tumors. The HAMNs can not only assist the loaded 5-ALA to effectively penetrate the stratum corneum but also provide 5-ALA with an acidic and oxygen-free environment to reduce the dimerization of 5-ALA molecules via Schiff-base bonds and formation of inactive pyrazine derivatives, thus maintaining its chemical structure and biological activity. The chemical stability of 5-ALA in HAMNs is confirmed by UV–vis spectra and mass spectra measurements. The 5-ALA@HAMNs display remarkable tumor elimination both in vitro and in vivo, even after storage at room temperature for nine months, making it a highly potential device for effective delivery of 5-ALA in cancer photodynamic therapy.

Overall optimization in microstructure and mechanical properties of 5 wt% SiC/7075Al composites by high-frequency electric pulse assisted treatment

Wei Zhao,Rui-feng Liu,Jie Yan,Xian Wang,Hong-wei Zhang,Wen-xian Wang

The microstructure evolution and mechanical properties of 5 wt% SiC/7075Al composites processed with a combination of three-step spark plasma sintering (SPS), hot rolling (HR), and high-frequency electric pulse assisted treatment (HEAT) processing were investigated herein. It was found that the HEAT tremendously promoted the recrystallization behavior after the hot rolling, leading to grain refinement and residual stress weakening. It can be attributed to the combination of the electrical (Electron wind) and thermal effects (Joule heat) of pulse current. Electron wind promotes the expansion of the movement of dislocations, providing the material basis for recrystallization. Joule heat and residual stress within the matrix provide the substance conditions. There was a remarkable improvement in strength and ductility, among which the increase in strength was mainly due to the combined effect of phase precipitation strengthening and grain refinement, while the increase in elongation was mainly attributed to grain refinement and residual stress weakening. Compared to those of the untreated samples, the average grain size decreased by 18.3%, residual stresses reduced by 70%, and tensile strength improved by 37.3%. High-frequency assisted treatment has a comprehensive improvement on the microstructure and mechanical properties of SiC/7075Al composites.

Synthesis of b-axis oriented ZSM-5 zeolite by mechanochemical-assisted quasi-solvent-free method and its MTO catalytic performance

Zihan Zhou,Xingwen Wang,Rui Yu,Rongli Jiang,Yu Gao,Xueshuai Chen,Huilin Hou

In this paper, b-axis oriented ZSM-5 zeolite was synthesized by solvent-free method with ammonia as growth regulator. Zeolites were characterized by modern detection techniques such as XRD, SEM, BET and NH 3 -TPD. The results showed that ammonia could not only promote the crystallization of ZSM-5 zeolite, but also direct the synthesis of ZSM-5 zeolite with b-axis oriented morphology, which was beneficial to enhance the selectivity of light olefins. B-axis oriented ZSM-5 zeolite did not need to be mixed and aged in aqueous solution, which could reduce the discharge of sewage, and avoided the generation of autogenic pressure in the crystallization process. Furthermore, it is consistent with the concept of environmental friendliness, which could guide the green preparation of industrial ZSM-5 zeolites.

Noninvasive Visualization of Sub-5 mm Orthotopic Hepatic Tumors by a Nanoprobe-Mediated Positive and Reverse Contrast-Balanced Imaging Strategy

Peng Lei,Hong Chen,Cai Feng,Xi Yuan,Zongling Xiong,Yanlan Liu,Weihua Liao

Delineation of small malignant lesions and their vasculature enables early and accurate diagnosis of hepatocellular carcinoma (HCC). However, it remains challenging to identify these features simultaneously by noninvasive imaging technology. Reverse contrast imaging emerges as a powerful means to detect early-stage HCC by taking inspiration from the intrinsic liver phagocytosis toward exogenous agents to generate negative tumor-to-normal tissue signals. However, this mechanism conflicts with the signal-enhancing requirements for vasculature visualization. Here, we solve this conundrum by designing a positive and reverse contrast-balanced imaging strategy based on a multifunctional PEG-Ta2O5@CuS nanoprobe that combines advanced gemstone spectral computer tomography (GSCT) with photoacoustic (PA) imaging. The nanoprobe exhibits preferential accumulation in Kupffer cells and hepatocytes over tumor cells, and its spectral properties are well matched with GSCT, leading to the enhancement of reverse contrast signals that enable clear delineation of 2–4 mm orthotopic HCC lesions. Meanwhile, its strong PA imaging capability at the second near-infrared (NIR-II) window makes vascular evaluation accessible by monitoring the positive signal enhancement derived from the limited tumor accumulation of the nanoprobe. In addition, the nanoprobe enables NIR-II photohyperthermia for timely tumor ablation. Overall, this proposed strategy shows potential in early detection and theranostics of HCC for improved clinical outcomes.

Synthesis of a phosphomolybdic acid-modified AlPO4-5/SAPO-34 composite catalyst and its catalytic performance in the MTO reaction

Jinbo Zhu,Xu Chen,Xiangge Sang,Gang Yang

SAPO-34 catalysts with high selectivity for light olefins were first synthesized via the introduction of phosphomolybdic acid (HPMo) and AlPO 4 -5 zeolite into the initial gel. The physical and chemical characteristics of the synthesized catalysts were determined by a series of techniques and the catalytic performance of the modified composite zeolites for the methanol-to-olefin (MTO) reaction was investigated. The results indicated that HPMo-modified SAPO-34 was featured with more Brønsted acid sites, more mesopores, and a smaller crystal size, thereby demonstrating superior catalytic performance. The further combination with AlPO 4 -5 (16.7 wt%) prolonged the lifetime of the HPMo-modified SAPO-34, which is thought in this paper related to its 12-ring straight channel (0.7–0.8 nm) and the absence of any Brønsted acid sites. The MTO tests showed that the light olefins selectivity for the modified composite zeolites reached 95.1 %, while the catalyst lifetime remained at 445 min

Fabrication of targeted and pH responsive lysozyme-hyaluronan nanoparticles for 5-fluorouracil and curcumin co-delivery in colorectal cancer therapy

Maolin Li,Yin Liu,Yanbo Liu,Jiawei Lin,Lei Ding,Songgu Wu,Junbo Gong

Green nanotechnology is considered a promising method to construct functional materials with significant anticancer activity , while overcoming the shortcomings of traditional synthesis process complexity and high organic solvents consumption. Thus, in this study, we report for the first time the rational design and green synthesis of functionalized 5-fluorouracil and curcumin co-loaded lysozyme-hyaluronan composite colloidal nanoparticles (5-Fu/Cur@LHNPs) for better targeted colorectal cancer therapy with minimized side effects. The functionalized 5-Fu/Cur@LHNPs exhibit stabilized particle size (126.1 nm) with excellent homogeneity (PDI = 0.1), favorable colloidal stabilities, and excellent re-dispersibility. In vitro cell experiments illustrate that the cellular uptake of 5-Fu/Cur@LHNPs was significantly improved and further promoted a higher apoptosis ratio of HCT-116 cells. Compared with the control group, the 5-Fu/Cur@LHNPs formulation group achieved effective inhibition (60.1 %) of colorectal tumor growth. The alcohol-free self-assembly method to construct 5-Fu/Cur@LHNPs is simple and safe for a translational chemotherapy drug, also to promote more robust delivery systems for treating colorectal cancer.

Semirational engineering of Cytophaga hutchinsonii polyphosphate kinase for developing a cost-effective, robust, and efficient adenosine 5′-triphosphate regeneration system

Qi Shen,Shi-Jia Zhang,Bin-Hui Xu,Zhi-Yu Chen,Feng Peng,Neng Xiong,Ya-Ping Xue,Yu-Guo Zheng

Investigating the impact of amine-functionalized ZSM-5 with varying Si/Al ratios on the adsorption of radioactive gaseous iodine

Rui-Li Yu,Qian-Fan Li,Hao-Ran Sun,Zhen-Le Li,Liang-Zhi Xia

In order to efficiently and rapidly capture radioactive iodine that impacts the environment, this study involves impregnating Tetraethylenepentamine (TEPA) into ZSM-5 zeolite with varying Si/Al ratios and evaluating its adsorption performance towards iodine. It is found that the optimal preparation level is 30 %, leading to a significant increase in the saturated adsorption capacity compared to non-impregnated molecular sieves , with a four-fold improvement. The adsorption rate is also enhanced. Various amines are utilized for impregnation, and FT-IR and molecular computation techniques are employed to investigate the adsorption mechanisms between these amines and iodine. The discovery reveals potential interactions between the amine groups and iodine, such as N ⋅ ⋅ ⋅ I halogen bonding and N–H ⋅ ⋅ ⋅ I hydrogen bonding . These findings provide valuable insights for developing iodine adsorbents, offering promising solutions for protecting ecological and living environments.

The integration of catalyst design and process intensification in the efficient synthesis of 5-hydroxymethyl-2-furancarboxylic acid from fructose

Wei He,Congcong Zhang,Wenyan Zhang,Yuchen Zhu,Zheng Fang,Lili Zhao,Kai Guo

The integration of catalyst design and process intensification in the synthesis of 5‑hydroxymethyl-2-furancarboxylic acid was realized directly from fructose. A novel bifunctional catalyst derived from lignin was developed for the dehydration of fructose. Supported catalysts derived from silver was developed for the oxidation of 5-hydroxymethylfurfural for 5‑hydroxymethyl-2-furancarboxylic acid. The product distribution both in dehydration and oxidation process would be controlled through the adjustment of solvent effect. The structure in bifunctional catalysts was adjusted to reveal the effect of molecular skeletons on the catalytic performance. The constitution of supported catalysts was investigated to illustrate the support effect. Accordingly, the mechanism and synergetic effect in the catalyst were proposed through computational studies based on density functional theory and control experiments. Microwave irradiation was applied in the dehydration reaction, requiring adequate and efficient energy supply. Flow chemistry was employed in the oxidation of HMF, improving reaction efficiency.

Interactive adsorption mechanism and product distribution of impurity gases on CO2 adsorption over amine-grafted ZSM-5/SBA-16 adsorbent

Tingting Liu,Yangyang Guo,Lei Luo,Meng Ye,Wen Liu,Tingyu Zhu

Solid amine adsorbents hold promising application prospects in the realm of industrial flue gas decarbonization. Nevertheless, there remains a need for substantial improvement in the cycling stability of solid amine adsorbents. Additionally, the competitive adsorption mechanism of solid amine adsorbents pertaining to flue gas components lacks thorough verification. In this study, amine-grafted micro-mesoporous ZSM-5/SBA-16 adsorbents were synthesized to improve the CO 2 adsorption capacity and investigate the effect of impurity gases on CO 2 adsorption. Various characterization techniques, including X-ray diffraction (XRD), thermogravimetric analysis (TGA), N 2 adsorption, and elemental analysis, were employed to analyze the properties of the adsorbents. The loading analysis of the micro-mesoporous molecular sieve revealed that ZS-A-2.0 exhibited the highest CO 2 adsorption capacity of 41.39 mg/g. Mass spectrometry was utilized to evaluate the co-adsorption experimentation involving multicomponent gases. The breakthrough curves of CO 2 displayed dual stages at low concentrations, suggesting the simultaneous occurrence of physical and chemical adsorption throughout the entire adsorption process. Based on temperature programming desorption (TPD) and in situ Fourier transform infrared spectroscopy (FTIR), the results indicated a notable enhancement in CO 2 adsorption due to the presence of H 2 O. Conversely, the presence of SO 2 and NO exhibited adverse effects on CO 2 adsorption, consequently hindering the formation of carbamate and (RNH 3 ) 2 CO 3 adsorption products. This study presents, for the first time, a comprehensive investigation into the interactive adsorption mechanism and product distribution between CO 2 and impurity gases. The findings presented herein provide valuable insights and essential support for practical flue gas applications.