查找使用阿拉丁产品的科研文献

Ketonization of propionic acid over TS-1 and Ti-Beta zeolites: Mechanism and effects of topology and hydrophobicity

Zijun Yang,Qiang Yu,Hua Wang,Qingfeng Ge,Xinli Zhu

Ketonization of propionic acid has been investigated on Lewis acidic TS-1 and Ti-Beta zeolites to understand the reaction mechanism and effects of pore topology and hydrophobicity. Characterizations showed that TS-1 and Ti-Beta (Si/Ti = 40) exhibited a similar acidity whereas TS-1 was more hydrophobic than the silanol-rich Ti-Beta. TS-1 showed higher activity, selectivity, stability and was more resistance to H 2 O than Ti-Beta. A combination of infrared spectroscopic, isotopic and kinetic studies showed that the molecularly adsorbed monodentate propionic acid is the most abundant reactive intermediate, and C-C coupling is the rate-determining step. The mechanism of ketonization of propionic acid at isolated tetrahedral Ti centers can be described by a Langmuir-Hinshelwood model. The turnover rate on TS-1-40 is ∼ 1.3 times higher than that on Ti-Beta-40, which is consistent with the lower fitted free activation energy, i.e., the energy difference between C-C coupling transition state and two co-adsorbed propionic acids at a Ti center. The slightly lower activation enthalpy on Ti-Beta-40 than TS-1-40 is over-compensated by much larger entropy penalty, due to more silanol groups and hydrogen bonded propionic acids in close proximity to the Ti center for Ti-Beta-40, which impose additional steric hindrance to bulkier C-C coupling complex at transition state and outweigh the difference of steric hindrance of pore confinement between MFI and BEA frameworks. This work provides insight into the ketonization mechanism on Lewis acidic zeolites, and indicates that moderate pore size with hydrophobic property promotes ketonization of carboxylic acid at isolated tetrahedral Ti centers confined in zeolites.

Beta-TCP scaffolds with rationally designed macro-micro hierarchical structure improved angio/osteo-genesis capability for bone regeneration

Feng Jianlang,Liu Junjie,Wang Yingqu,Diao Jingjing,Kuang Yudi,Zhao Naru

The design of hierarchical porous structure in scaffolds is crucial for bone defect regenerative repair. However, bioceramic materials present a challenge in precisely constructing designed micropores owing to the limitation of forming process. To investigate micropore shape influences bone regeneration in bioceramic scaffolds with macropores, hierarchical porous scaffolds with interconnective macropores (~400 μm) and two types of micropores (spherical and fibrous) were prepared using a combination of direct ink writing (DIW) and template sacrifice methods. Compared to the scaffold with spherical micropores, the scaffold with highly interconnected fibrous micropores significantly improved cell adhesion and upregulated osteogenic and angiogenetic-related gene expression in mBMSCs and HUVECs, respectively. Furthermore, in vivo implantation experiments showed that hierarchical scaffolds with fibrous micropores accelerated the bone repair process significantly. This result can be attributed to the high interconnectivity of fibrous micropores, which promotes the transportation of nutrients and waste during bone regeneration. Our work demonstrates that hierarchical porous scaffold design, especially one with a fibrous micropore structure, is a promising strategy for improving the bone regeneration performance of bioceramic scaffolds. Graphical Abstract

Modification of nanofiltration membranes using beta-cyclodextrin derivatives with different functional groups for enhanced removal of organic micropollutants

Xinxin Wei,Kaiming Fan,Peng Cheng,Yanling Liu,Shengji Xia

Simultaneous enhancement in the removal of organic micropollutants (OMPs) and water permeance is highly desirable for nanofiltration (NF)-based drinking water treatment . This study employed two cyclodextrin derivatives with different functional groups, i.e., (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) and sulfobutylether-β-cyclodextrin (SBECD), as aqueous additives for polyamide (PA) membrane fabrication. Characterization results revealed that HP-β-CD tended to enrich piperazine (PIP) monomers through hydrogen bonding, resulting in a thin but dense PA layer. Conversely, SBECD moderated PIP diffusion through electrostatic forces and steric hindrance , participated more in the interfacial polymerization reaction and yielded an active layer with a coexistence of polyester and polyamide. Both the CD derivative modified membranes exhibited improved surface hydrophilicity , enhanced roughness, and reduced active layer thickness, leading to over 60 % water permeance improvement without the obvious variation of pore size. This enabled the optimal membranes, especially the HP-β-CD incorporated one, highly advantageous in overcoming the trade-off effect between water permeance and OMP rejection. Meanwhile, the strongly negatively charged SBECD modified membrane showed reduced rejections for divalent cations, making it more resistant to scaling. This study offers an efficient approach to tailoring membrane water/solute selectivity and solute/solute selectivity, which has great potential in NF membrane development for drinking water treatment.

Combination of 1,8-cineole and beta-caryophyllene synergistically reverses cardiac hypertrophy in isoprenaline-induced mice and H9c2 cells

Chunmei Bai,Qianqian Ma,Qi Li,Lijun Yu,Dong Zhen,Mingjie Liu,Chengxi Wei

Combination drug therapy has become an effective strategy for chronic metabolic disease, especially cardiovascular disease. In the present study, possible drug combinations were screened and the mechanism of the combinations against cardiac hypertrophy was examined within 1,8-cineole, β -caryophyllene, linalool, and β -pinene.H9c2 cells were treatment with 1,8-cineole, β -caryophyllene, linalool, and β -pinene individually or in combination for 24 h after isoprenaline stimulation. Cell viability was detected by the MTT assay. Subsequently, bioinformatic analysis and network pharmacology were used to reveal the multi-targeted synergistic therapeutic effect of the combination treatment compounds on cardiac hypertrophy. Ultimately, western blot and elisa was performed to analyses the protein expression in vivo . MTT results found that 1,8-cineole and β -caryophyllene synergistically increased cell viability with CalcuSyn software analyses. Specifically, bioinformatic and network pharmacology analysis showed PTGS2, TNF, IL-6, AKT1, NOS2, and CAT were identified as the key targets. P13K-AKT signaling pathway was involved in the reversal of cardiac hypertrophy by the combination of 1,8-cineole and β -caryophyllene. The in vitro results indicated that the combination synergistically treated the isoprenaline-induced mice against structural and functional myocardial damage via the P13K-AKT signaling pathway. Collectively, the combined application of 1,8-cineole and β -caryophyllene synergistically reverses cardiac hypertrophy in isoprenaline-induced H9c2 cells and mice.

Controlled SPION-Exosomes Loaded with Quercetin Preserves Pancreatic Beta Cell Survival and Function in Type 2 Diabetes Mellitus

Manjiao Zhuang,Lei Rao,Yadi Chen,Shangying Xiao,Haishan Xia,Jiangyong Yang,Xiaohua Lv,Dongyun Qin,Chunjie Zhu

Synthesis of n-butanol from ethanol over Pt-Y/beta catalyst: Synergistic catalysis of yttrium and platinum site

Haowei Liu,Tao Zheng,Tianli Hui,Rui Zhang,Xianghai Meng,Wenshuai Zhu,Haiyan Liu,Zhichang Liu

Conversion of ethanol to high-value alcohols is an attractive approach for developing renewable biofuels, the key is to develop stable and high-efficient catalysts. In this work, based on the preparation strategy of heteroatomic Beta zeolites, a bifunctional Pt-Y/Beta catalyst was prepared by solid-state ion exchange and impregnation. Through characterization techniques such as TEM, NMR and XAS, it was confirmed that the Y species were incorporated into the framework of Beta zeolite by interacting with the silanol groups located at the defect sites, while the Pt species were confirmed to be present on the surface of the zeolite in the form of dispersed nanoparticles . The unique structure form and the favorable spatial proximity of the two metallic active sites lead to a synergistic catalysis, which enable a one-step conversion of ethanol to n-butanol with exceptionally high selectivity of 68 %. In situ DRIFT characterization, ethanol-TPD and relay experiment results show that in the ethanol to n-butanol reaction, the Pt species in Pt-Y/Beta catalyst serves as the active center for the dehydrogenation of ethanol and the hydrogenation of crotonaldehyde and crotyl alcohol, while the Y species is responsible for catalyzing the condensation reaction of acetaldehyde.

Design optimization of CsPbBr3 nanocrystals into zeolite Beta composites as ultra-stable green emitters for backlight display applications

Bohan Li,Yuchi Zhang,Yan Xu,Zhiguo Xia

CsPbBr3 nanocrystals (NCs) with highly efficient narrow-band green emission are promising candidates in display applications. However, the poor stability of CsPbBr3 NCs is always a challenge for future development. Herein, we designed and prepared CsPbBr3 NCs encapsulated into zeolite Beta (denoted as CsPbBr3-Beta) composite via an optimized high temperature solid-state method, and the as-obtained power materials exhibited green emission peaking at 520 nm with a narrow full-width at half-maximum (FWHM) of 25 nm and a high photoluminescence quantum yield (∼61%). We further demonstrated the ultra-high luminescent stability of CsPbBr3-Beta composite by treating under a 150 °C treatment, soaking in water over 30 days, as well as applying in 450 nm light-emitting devices (LED) for 20 days. Ultimately, white-light-emitting devices (WLEDs) constructed by the green-emitting CsPbBr3-Beta composite and commercial blue chip and red K2SiF6:Mn4+ phosphor achieved a color gamut of 123.5% National Television System Committee standard (NTSC) and high luminous efficiency (LE = 95 lm W−1). This work highlights the encapsulation process and feasible solid-state reaction methodology to fabricate CsPbBr3 NCs confined in a microporous molecular sieve with high luminescent stability and performance, significantly expanding its great potential to be used in optoelectronic fields.

Facile method for iodide ion detection via the fluorescence decrease of dihydrolipoic acid/beta-cyclodextrin protected Ag nanoclusters

Shu Huan Ren,Shi Gang Liu,Yu Ling,Nian Bing Li,Hong Qun Luo

In this work, novel photoluminescent Ag nanoclusters (Ag NCs) with red emission are synthesized and successfully used for detecting iodide ion (I − ). The dihydrolipoic acid (DHLA) is used as the stabilizing agent and beta-cyclodextrin (β-CD) is used as the auxiliary stabilizing agent. DHLA and β-CD are combined with Ag atoms by the formation of Ag S bonds and hydrophobic interaction, respectively. Functionalization of β-CD endows good photoluminescent properties and solubility in water to the Ag NCs. The obtained DHLA and β-CD-protected Ag NCs (DHLA/β-CD-Ag NCs) are spherical and display a dispersed state. However, the DHLA/β-CD-Ag NCs are aggregated in the presence of I − , accompanied by the decrease in their fluorescence intensity . Because the integrity of β-CD cavities is retained on the surface of DHLA/β-CD-Ag NCs, which preserves their capability for I − host–guest recognition, the DHLA/β-CD-Ag NCs combine with I − through the formation of inclusion complexes. Based on this phenomenon, the prepared DHLA/β-CD-Ag NCs can be designed as a novel fluorescent probe for I − detection. The limit of detection (LOD) is calculated as 0.06 μM, indicating that it is an ideal probe for I − detection in practical applications.

Carnosic Acid Prevents Beta-Amyloid-Induced Injury in Human Neuroblastoma SH-SY5Y Cells via the Induction of Autophagy

Liu Jie,Su Hua,Qu Qiu-Min

Beta-amyloid (Aβ), the hallmark protein in Alzheimer’s disease (AD), induces neurotoxicity that involves oxidative stress and mitochondrial dysfunction, leading to cell death. Carnosic acid (CA), a polyphenolic diterpene isolated from the herb rosemary ( Rosemarinus officinalis ), was investigated in our study to assess its neuroprotective effect and underlying mechanism against Aβ-induced injury in human neuroblastoma SH-SY5Y cells. We found that CA pretreatment alleviated the Aβ 25–35 -induced loss of cell viability, inhibited both Aβ 1–42 accumulation and tau hyperphosphorylation, reduced reactive oxygen species generation, and maintained the mitochondrial membrane potential. Moreover, CA increased the microtubule-associated protein light chain 3 (LC3)-II/I ratio and decreased SQSTM1(p62), indicating that CA could induce autophagy. Autophagy inhibitor 3-methyladenine (3-MA) attenuated the neuroprotective effect of CA, suggesting that autophagy was involved in the neuroprotection of CA. It was also observed that CA activated AMP-activated protein kinase (AMPK) but inhibited mammalian target of rapamycin (mTOR). Furthermore, blocking AMPK with si-AMPKα successfully inhibited the upregulation of LC3-II/I, prevented the downregulation of phosphorylation of mTOR and SQSTM1(p62), indicating that CA induced autophagy in SH-SY5Y cells via the activation of AMPK. These results suggested that CA might be a potential agent for preventing AD.

H-Beta Zeolite as Catalyst for the Conversion of Carbohydrates into 5-Hydroxymethylfurfural: The Role of Calcination Temperature

Xinyi Xing,Wanni Liu,Siquan Xu,Jianxiu Hao

H-Beta zeolite is a solid acid catalyst commonly utilized in the catalytic conversion of biomass resources. In this study, H-Beta zeolite was calcined at different temperatures (350, 550, 750, and 1000 °C) to explore the effects of high temperature-induced dealumination on its physicochemical properties and its catalytic ability to convert glucose into 5-hydroxymethylfurfural (HMF). It was shown that as the calcination temperature increased, the Si-O-Al bond of H-Beta zeolite was broken and its dealumination effect was enhanced. Dealumination led to the collapse of the framework of H-Beta zeolite and a reduction in the number of acid sites, which in turn reduced its catalytic performance and the efficiency of HMF formation from glucose. Furthermore, H-Beta zeolite exhibited an extraordinary catalytic ability for the production of HMF from carbohydrates. Using glucose and cellulose as substrates, superior HMF yields of 91% and 46%, respectively, were achieved under optimal reaction conditions. Further, calcination removes carbon deposits in the recovered H-Beta zeolite, but it affects the cycling stability of the catalyst. Meanwhile, the by-products formed during the synthesis of HMF from glucose catalyzed by H-Beta zeolite catalyst were also clearly detected.

Highly efficient Ni/Beta catalyst for one-step hydrodeoxygenation-isomerization of fatty acid ester to bio-jet fuel

Wenjing Zhang,Tinghu Wang,Yiming Gao,Yaru Xue,Furang Li,Chuanrui Pang,Jianye Fu,Xinmei Liu,Yuchao Lyu

The catalytic performance of bifunctional catalyst for one-step hydrodeoxygenation of fatty acid esters to bio-jet fuel is contingent upon the features of metal component and acid support. However, it remains challenging to simultaneously modulate these structural features with the impregnation method. Herein, the metal particle size, pore structures and acidity of Ni/Beta catalysts are regulated simultaneously during the citric acid-assisted impregnation process. The particle size of Ni over the Ni/Beta catalyst is greatly decreased due to the steric and coordination effect of citric acid on metal. The electron density of the small Ni particle is reduced by the enhanced electron transfer between Ni and Beta. Besides, the dealumination effect of citric acid on Beta zeolite reduces strong Brønsted acid sites and introduces 0.85 times more mesopores into the Ni/Beta catalyst, compared with the counterpart obtained by conventional impregnation method. The enhanced metal dispersion over the Ni/Beta catalyst promote hydrodeoxygenation of reactants and favor hydrodecarbonylation reaction path. The reduced Brønsted acid sites and abundant mesopores inhibit cracking of intermediate and products. The space–time yield of C 12 and C 11 reaches 33.4 mmol·g −1 ·h −1 in hydrodeoxygenation of methyl laurate which is the highest value reported.

Metal-acid synergistic catalysis accelerates the hydrogen borrowing amination of alcohols by confining Ru sites in Beta zeolite

Yue Wu,Cailing Chen,Zhuo Xiong,Meng Xu,Yue Zhao,Yihu Dai,Yu Han,Yu Zhou,Xiaoling Liu,Jun Wang

Direct hydrogen transfer amination of alcohols with amines is an environmentally friendly and atom-economical route for the synthesis of N-alkylamines. Noble metal species are highly catalytic active sites, but the exorbitant price makes the urgency to boost the atom efficiency with stable recyclability. Herein, we demonstrated that encapsulation of Ru nanoparticles (NPs) within BEA zeolite through direct hydrothermal approach greatly promoted the catalytic efficiency in the N-alkylation of aromatic alcohols and amines under additive- and solvent-free conditions, resulting in the high yield (∼93 %), maximum turnover number (TON) of 12,822 and turnover frequency (TOF) of 9012 h −1 , with stable recyclability and extendable substrate scope. The kinetic studies and in-situ characterizations revealed that the synergy of confined Ru NPs and adjacent acid sites of BEA zeolite significantly promoted the C–H bond activation in the rate-determining step of alcohol dehydrogenation into aldehydes. Besides, the acid sites also accelerated the condensation of aldehyde intermediates and anilines to promote the kinetic equilibrium, while the moderate strength of the Ru–H bond resulting from the confined Ru NPs is advantageous to balance the dehydrogenation and hydrogenation steps to reach the fascinating H-transfer process.