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排序方式: 共有138条查询结果,搜索用时 15 毫秒
1.
Tho Duc Khanh Nguyen Stefania Rabasco Alicia A. Lork Andre Du Toit Prof. Andrew G. Ewing 《Angewandte Chemie (International ed. in English)》2023,62(28):e202304098
We used correlative transmission electron microscopy (TEM) and nanoscale secondary ion mass spectrometry (NanoSIMS) imaging to quantify the contents of subvesicular compartments, and to measure the partial release fraction of 13C-dopamine in cellular nanovesicles as a function of size. Three modes of exocytosis comprise full release, kiss-and-run, and partial release. The latter has been subject to scientific debate, despite a growing amount of supporting literature. We tailored culturing procedures to alter vesicle size and definitively show no size correlation with the fraction of partial release. In NanoSIMS images, vesicle content was indicated by the presence of isotopic dopamine, while vesicles which underwent partial release were identified by the presence of an 127I-labelled drug, to which they were exposed during exocytosis allowing entry into the open vesicle prior to its closing again. Demonstration of similar partial release fractions indicates that this mode of exocytosis is predominant across a wide range of vesicle sizes. 相似文献
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Fangzhou Li Dr. Errui Li Dr. Krishanu Samanta Zhaoxi Zheng Dr. Lianqian Wu Albert D. Chen Prof. Dr. Omar K. Farha Dr. Richard J. Staples Prof. Dr. Jia Niu Prof. Dr. Klaus Schmidt-Rohr Prof. Dr. Chenfeng Ke 《Angewandte Chemie (International ed. in English)》2023,62(50):e202311601
Boron trifluoride (BF3) is a highly corrosive gas widely used in industry. Confining BF3 in porous materials ensures safe and convenient handling and prevents its degradation. Hence, it is highly desired to develop porous materials with high adsorption capacity, high stability, and resistance to BF3 corrosion. Herein, we designed and synthesized a Lewis basic single-crystalline hydrogen-bond crosslinked organic framework (HCOF-50) for BF3 storage and its application in catalysis. Specifically, we introduced self-complementary ortho-alkoxy-benzamide hydrogen-bonding moieties to direct the formation of highly organized hydrogen-bonded networks, which were subsequently photo-crosslinked to generate HCOFs. The HCOF-50 features Lewis basic thioether linkages and electron-rich pore surfaces for BF3 uptake. As a result, HCOF-50 shows a record-high 14.2 mmol/g BF3 uptake capacity. The BF3 uptake in HCOF-50 is reversible, leading to the slow release of BF3. We leveraged this property to reduce the undesirable chain transfer and termination in the cationic polymerization of vinyl ethers. Polymers with higher molecular weights and lower polydispersity were generated compared to those synthesized using BF3 ⋅ Et2O. The elucidation of the structure–property relationship, as provided by the single-crystal X-ray structures, combined with the high BF3 uptake capacity and controlled sorption, highlights the molecular understanding of framework-guest interactions in addressing contemporary challenges. 相似文献
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The aim of this work was to evaluate the influence of US on the properties of the fluconazole emulsions prepared using imidazolium-based ILs ([Cn C1im]Br). The effects of the preparation method (mechanical stirring or US), US amplitude, alkyl chain length (of [C12C1im]Br or [C16C1im]Br), and IL concentration on the physicochemical properties were evaluated. Properties such as droplet size, span index, morphology, viscosity encapsulation efficiency, and drug release profile were determined. The results showed that US-prepared emulsions had a smaller droplet size and smaller polydispersity (Span) than those prepared by mechanical stirring. Additionally, the results showed that emulsions prepared with [C16C1im]Br and US had spherical shapes and increased stability compared to emulsions prepared by MS, and also depended on the IL concentration. The emulsion prepared by US at 40% amplitude had increased encapsulation efficiency. US provided a decrease in the viscosity of emulsions containing [C12C1im]Br; however, in general, all emulsions had viscosity close to that of water. Emulsions containing [C16C1im]Br had the lowest viscosities of all the emulsions. The emulsions containing the IL [C16C1im]Br had more controlled release and a lower cumulative percentage of drug release. The IL concentration required to prepare these emulsions was lower than the amount of conventional surfactant required, which highlights the potential synergic effects of ILs and US in preparing emulsions of hydrophobic drugs. 相似文献
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We consider a scheduling problem motivated by mining in remote off-grid areas. In this model, mines have pre-assigned mineral processing jobs and their own machine for executing these jobs. Each job also needs a certain amount of electricity in order to get completed. The electricity, on the other hand, is of limited supply and must be shared between the mines. We present a mathematical formulation of the problem and a Lagrangian relaxation based heuristic. Computational results which compares our heuristic with genetic algorithm and simulated annealing are also presented. 相似文献
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Manjusha Chakraborty Chidambaram Soundrapandian Swapankumar Ghosh Manoj K. Mitra 《Journal of solid state chemistry》2011,184(9):2439-2445
The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 Å in pristine LDH to 21.3 Å in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion. 相似文献
10.
Mingbo WangQingling Feng Xiaodong GuoZhending She Rongwei Tan 《Polymer Degradation and Stability》2011,96(1):107-113
In this paper, we document the process and findings of preparing dual poly (lactide-co-glycolide)/chitosan microspheres (PLGA/CS MSs) for osteoinductive oligopeptide derived from BMP-2 (abbreviated as Peptide-24). Through adjusting the amount of Peptide-24, three kinds of PLGA/CS MSs were successfully constructed in twice encapsulations. We studied the morphology, size distribution and loading efficiency of the PLGA/CS MSs. We also focused on the pH change of the environment and the molecular weight of the matrix during the degradation process of PLGA/CS MSs. More specifically, the release of Peptide-24 from three kinds of PLGA/CS MSs was monitored in PBS at 37 °C and pH 7.4. The structural stability of the released Peptide-24 was detected by Far-UV circular dichroism and MALDI-TOF-MS analysis. The mean sizes of the three kinds of PLGA/CS MSs are 47.5, 63.0 and 89.1 μm; and their drug-loading rates are 2.61, 3.21 and 2.21%, respectively. Comparing with Chitosan microspheres (abbreviated as CS MSs), the PLGA/CS MSs have excellent release curves with zero-order kinetics and controllable model. The incubation solution of PLGA/CS MSs avoided producing acid environment as poly (lactide-co-glycolide) microspheres (PLGA MSs) did, which was explained by analyzing the molecular weight of the matrix. The released oligopeptide kept its original structure and relative molecular weight throughout the procedures of encapsulation, storage and release. This indicates its structure stability. Thus, we conclude that dual PLGA/CS MSs is a promising vehicle that is suitable for the delivery of bioactive factors. 相似文献