查看更多>>摘要：Here, a novel antibacterial agent (IM-POP-Ag) through encapsulation of Ag nanoparticles (AgNPs) into an imidazole-based porous organic polymer (IM-POP) was developed for synergistic antibacterial and wound healing. IM-POP with an ultrahigh N content of 38.42 at% was synthesized via the copolymerization of cheap and industrially mass-produced imidazole-2-carbaldehyde and melamine, via catalyst-free Schiff base chemistry, which could realize the effectively anchor of Ag on the porous skeleton (with an Ag loading of 26.01 wt%), avoiding the aggregation and reducing the toxicity of AgNPs greatly. The inherent porosity of POP realizes the effectively control on the size of AgNPs and the coordination of Ag+ changed imidazole into imidazolium, gifting the antibacterial activity to the carriers. As a result, IM-POP-Ag presented a synergistic antibacterial activity against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli.). For example, at the same Ag content, the survival rates of E. coli and S. aureus in response to 200 mu g mL(-1) IM-POP-Ag (equivalent to 50 mu g mL(-1) AgNPs) were 3.44 +/- 0.21% and 6.34 +/- 0.40%, respectively, far outperforming that of bare AgNPs (12.19 +/- 0.54% and 20.20 +/- 0.19%). In vivo experiments on mice testified IM-POP-Ag could significantly promote the healing rate of infected wounds which could facilitate the growth of vessel and hair follicle, accelerating epithelialization. Hence, this novel and mass-produced antibacterial agent provides a new strategy and theoretical basis for the application of AgNPs with higher efficacy and biocompatibility in the near future.
查看更多>>摘要：While structural and chemical properties of adsorbents are largely known, energetic properties are mostly not known yet. In cation exchanged zeolites, the type, number, and position of cations have a major influence on energetic properties. Therefore, the energetic values of cations were investigated systematically on LTA zeolites. In these CaNaA materials, Na+-cations were selectively replaced by Ca2+-cations with calcium exchange rates between 8.7% and 92.1%. The cation sites were determined by crystal structure analysis of X-ray powder diffraction data (XRPD). Rietveld analysis showed the sequence of emptying Na+-cations from the various cation sites and the occupancy sequence of Ca2+-cations as a function of the exchange rate. In addition, sensor gas calorimetry was used to measure the heat of adsorption using methane as a sample molecule. The results show an increase in capacity and heat of adsorption up to an exchange rate of 68.6%. At higher exchange rates, the capacity and heat of adsorption decrease again. Characteristic plateaus of the heat of adsorption were found for all materials. By combining XRPD and calorimetry, the plateaus of the heat of adsorption were assigned to the different cation positions inside the zeolite cages and the respective energetic contributions were determined. Ca2+-cations represent energetically more valuable adsorption sites compared to Na+-cations. Furthermore, differences in the energetic values of the various cation sites were identified. It was also found, that the interactions with the zeolite framework provide the largest contribution.
Best, Felix Rieck genanntMundstock, AlexanderRichter, HannesKissling, Patrick A....
8页
查看更多>>摘要：Water permeation through a hydrophilic zeolite membrane can be used to promote reactions under equilibrium controlled conditions through the in situ removal of the by-product water. In the methylamine synthesis, mono(MMA), di- (DMA) and trimethylamine (TMA) are formed by the successive methylation of ammonia with methanol (MeOH) over a mildly acidic catalyst. The methylamine yield can be increased through selective water extraction from the reactor through a membrane. Since both reactants and water have similar molecular kinetic diameters below 3.7 angstrom, because of the limited steam selectivity of the commonly used hydrophilic Na-LTA membrane (zeolite 4A), not only water has been removed. Therefore, in this work a K-LTA membrane, which was obtained by ion exchange with a reduced pore window diameter of 3 angstrom and thus with a higher water selectivity, was used in the membrane-supported methylamine synthesis. When replacing the Na-LTA with the KLTA membrane, the H2O/MeOH mixed gas separation factor increases up to 1100 and the H2O/NH3 separation could also be improved. This in turn leads to an overall boost of the higher methylated amines DMA and TMA in methylamine synthesis. When using the narrow-pore aluminosilicate catalyst H-SSZ-13 with CHA structure, the application of the K-LTA membrane increases the share of the industrially desired product DMA from 51% without membrane to 74% with slightly increased conversion. When using the large-pore catalyst H-MOR, the thermodynamically most stable product TMA can be formed and the selectivity was increased from 35% without membrane to 41% with the K-LTA membrane.
查看更多>>摘要：A design of efficient adsorbent for CO2 selective capture without secondary pollution and by low carbon footprint strategies is crucial towards the decreasing of C-2 atmospheric concentration. To answer to this demand, in this work we present a versatile and robust technique for production of functionalized 3D porous graphene/polymer monolithic structures based on aqueous self-assembly process, in which the graphene functionalization occurred simultaneously throughout spontaneous addition of functionalized waterborne polymer particles. It was shown that the composite monoliths are truly products-by-process, as their final characteristic can be designed during the synthesis by varying the reaction parameters. The addition of polymer particles to the graphene skeleton was an excellent tool to control the textural properties, resulting in enlarged fraction of micropores, because the polymer particles act as spacers between rGO platelets. The higher microporosity certainly affected positively the performance, especially the selectivity of CO2 adsorption over that of N2, offering alternative technology for post production CO2 capture.
查看更多>>摘要：Solid-state nuclear magnetic resonance (SSNMR) spectroscopy is a valuable technique for characterizing the structural features of zeolites. In recognition of this, the International Zeolite Association's online Database of Zeolite Structures has recently been expanded to incorporate representative SSNMR spectra of zeolites. This paper reports a comprehensive collection of 73 P-31 SSNMR spectra of aluminophosphate zeolites with 31 framework types that has been added to database. The scientific literature on aluminophosphate zeolites was extensively searched for P-31 SSNMR spectra with resolution such that the number of peaks in the spectrum ideally corre-sponded with the number of P sites in the reported crystal structures. These spectra were digitized, fit with a model spectrum informed by the known crystal structure, then added to the Database of Zeolite Structures. This comprehensive collection of P-31 SSNMR spectra and crystal structures enabled an investigation of the rela-tionship between various parameters describing the geometry around the P sites and the P-31 chemical shifts. It was found the P-31 chemical shifts are best correlated to the average P-O-Al bond angles. The correlation equation presented here is based on the largest available collection of spectra with corresponding crystal structures determined from single-crystal X-ray diffraction. It is expected that this comprehensive collection of P-31 SSNMR spectra and the chemical shift-to-structure correlation equation derived from it will be of interest and utility to the zeolite research community.
查看更多>>摘要：Nanopores in organic shale reservoirs are of great significance for shale gas accumulation and carbon dioxide geological sequestration. To explore the multifractality and classification of nanopores in the Lower Cambrian Niutitang Formation shales, nine shale samples were selected from the well TX1 in North Guizhou, South China. Then, we conducted TOC analysis, XRD analysis and SEM to investigate shale material composition and nanopore morphology and low temperature N2 and CO2 adsorption experiments were used to quantitatively characterize the nanopore structure. The multifractal theory was applied to study the spatial distribution of nanopores. Results showed that nanopores in Niutitang Formation shales are mainly organic pores with pore sizes less than 50 nm, followed by intraparticle dissolution pores; interparticle pores are rarely observed. According to the results of the N-2 adsorption experiments, our samples can be divided into three types. Type I samples have the highest average pore size, whereas Type III samples have the highest pore volume and surface area. Results of the CO2 adsorption experiments indicated a trimodal distribution of measured pores. Our study revealed the multifractality of nanopores, and the complexity of pores measured via N2 adsorption is stronger than that measured via CO2 adsorption. Results of multifractal analysis via N2 adsorption demonstrated that Type I samples have the strongest pore agglomeration and Type III samples have the most uniform pore size distribution. For nanopores measured via CO2 adsorption, subtle differences exist in multifractal characteristics of the various samples. An increase in the pore volume measured via N(2 & nbsp;)adsorption corresponds to a decrease in pore aggregation and heterogeneity and an increase in pore connectivity. For nanopores detected via CO2 adsorption, no obvious correlations were observed between the pore structure and multifractal parameters. We propose a new nanoporeclassification scheme based on pore heterogeneity and connectivity. Nanopores of the selected samples can be classified as micropores (< 10 nm), mesopores (10-25 nm), and macropores (> 25 nm). Fractal properties of nanopores obtained from SEM images showed that mesopores have weaker heterogeneity and better connectivity than micropores and macropores, which also indicates the reasonability of our pore classification.
查看更多>>摘要：This paper reports secondary cracking suppression through Pt/H-BEA in n-C-16 hydrocracking. H-BEA (C) and H-BEA (H) of SiO2/Al2O3 ratios: 17, 23, and 25 were prepared by hydrothermal method and steam-assisted conversion method, respectively, and platinum loading was performed using incipient wetness impregnation. Pt/H-BEA (H) catalysts exhibited predominantly mesoporous structure by nitrogen physisorption and lower acid site density by NH3-TPD and Pt/H-BEA (C) exhibited unusually high mesoporosity based on our synthesis gel chemistry. Both catalysts had high secondary cracking reactions suppression but Pt/H-BEA23 (H) exhibited superior and perfect suppression with C-6/C-10 similar to 1 and symmetrical cracking products carbon number molar distribution at several n-C-16 conversions. Pt/H-BEA (H), consequently, had highest jet fuel hydrocarbons (C9+) selectivity with 81% achieved by Pt/H-BEA23 (H) at 50% conversion. It, additionally, had lower coke deposition which decreased with increased SiO2/Al2O3 ratio as a result of lower diffusion limitations and secondary cracking reactions. Pt/H-BEA, in conclusion, exhibits excellent ability to suppress secondary cracking reactions for high jet fuels hydrocarbons selectivity and diesel selectivity in Fischer-Tropsch wax hydrocracking considering n-C-16 as a feed model and H-BEA (H) greatly improves the performances.
查看更多>>摘要：In this study, in-silico properties of Gingerol (Gin) and Letrozole (Let), as two potential anti-cancer drugs, were investigated and some significant ADME drawbacks were predicted. Accordingly, to address the drawbacks, mesoporous silica nanoparticles (MSNs) were prepared, functionalized with zinc, amine, and graphene oxide (GO) (MZNG), and employed for loading and delivery of the both to breast cancer cells in-vitro. Biophysical analysis showed that Let and Gin-loaded MZNGs have spherical structure with a mean diameter of ~210 nm. The MZNGs provided high entrapment efficiency of Let and Gin with a pH-sensitive sustained release profile. The cytotoxicity assay demonstrated that loading of the drugs into MZNG significantly improves their inhibitory effects on the breast cancer cells, which was attributed to enhanced cellular uptake. Inhibition of cancer cell proliferation and cell arrest in G0/G1 phase was due to the regulation of the expression levels of the studied genes in breast cancer cells. Upon treatment with the drugs, a downregulation for Bcl-2, MMP-2, MMP-9, CyclinD and CyclinE genes, and an upregulation for Bax, Caspase3 and Caspase9 genes were observed. Furthermore, the Let/Gin-loaded MZNG inhibited migration and invasion in the breast cancer cells. Our results suggested that MZNG provided a suitable and efficient nanosystem for co-delivery of Let and Gin with synergic effect. The Let/ Gin-loaded MZNG induced apoptosis and inhibition of migration and proliferation in the breast cancer cells. Overall, the prepared nano-formulation holds a great promise for the treatment of not only breast cancer but also other cancers.
查看更多>>摘要：The effect of proximity of two different SiO2/Al2O3 ratio ZSM-5 catalysts with complementary acidic properties on their catalytic synergy over methanol stepwise aromatization was specifically studied based on a series of different packing modes. The results showed that the powder mixing mode with high proximity excessively enhanced the synergy by intensifying mass transfer between two catalysts. Although it presented a high aro-matics selectivity of 57.2%, but the catalyst lifetime was only 10 h due to the intense reverse of poly-methylbenzene. The granule mixing mode with larger particle size only slightly improved the catalyst lifetime. Packing two ZSM-5 catalysts in separated dual beds mode could prolong the lifetime to 157 h but the aromatics selectivity was reduced to 21.0%, indicating that low proximity is not favored the catalytic synergy. Interest-ingly, the suitable proximity of designed alternative sequence beds mode not only intensified intermediates transport to some extent but also relieved the negative influence of aromatic reversion. The moderate synergy remarkably increased the aromatics selectivity to 28.9% with a satisfactory lifetime of 117 h. This work pre-liminarily elucidates the effect of proximity determined by the spatial organization of double ZSM-5 catalysts on their catalytic synergy for methanol aromatization.
查看更多>>摘要：A highly efficient induction focusing on the nucleation promotion and the framework elements consumption always plays a critical role in the design and synthesis of nanosized zeolitic materials. In this work, the highly crystalline nanosized Beta zeolite was hydrothermally synthesized following the seed-assisted strategy without using any additional organic structure directing agents (OSDAs) or preformed composite building units (CBUs). The physicochemical properties of the resulting nanosized zeolite Beta was strongly affected by the composition of the initial aluminosilicate gel, which can be facilely optimized just by matching the Si/Al molar ratio to the crystallization treatment. The superior mesoporous and strong acidic properties were obtained at a Si/Al ratio of similar to 50. As for the framework assembly, Raman and XRD results reveal that the key factor is the continuous formation and accumulation of 6-ring structures (6-MRs) inside the aluminosilicate gel. After a 4 days and 22 h' sufficient induction, the 5-MR and 4-MR structures were built through the bonding of 6-MR structures when fabricating the mtw, bea, and mor CBUs, and finished the assembly of Beta zeolite in 2 h. The obtained nanosized Beta zeolite exhibits a great crystallinity and a highly accessible mesopore structure that was composed solely of interparticle-type mesopores, as well as a strong Bronsted-type acidity.
NSTL
Elsevier