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791.
Miguel Teixeira Marta C. Campo David A. Pacheco Tanaka Margot A. Llosa Tanco César Magen Adélio Mendes 《Carbon》2011,49(13):4348-4358
Composite carbon molecular sieve membranes (c-CMSM) were prepared from phenolic resin loaded with boehmite by a single dipping–drying–pyrolysis step. The composite membrane was analyzed by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, mercury porosimetry, CO2 adsorption and permeation experiments. It was produced a 2 μm thick composite uniform layer on top of a α-Al2O3 support. The composite top layer exhibited nanowires of Al2O3 1–2 nm thick and 10–30 nm long well dispersed in a microporous carbon matrix. The micropores network accounted for 63% of the total pore volume (DR isotherm). The c-CMSM exhibited ideal O2/N2 and C3H6/C3H8 permselectivities of 5 and 15, respectively. The performance of the c-CMSM for pair C3H6/C3H8 was above the upper bound curve for polymeric membranes, making it a promising vehicle for olefin purification. 相似文献
792.
Nina Hauptman Marta Klanjšek Gunde Matjaž Kunaver Marija Bešter-Rogač 《Journal of Coatings Technology and Research》2011,8(5):553-561
The influence of dispersing additives on the electrical conductivity of carbon black pigments dispersed in an organic medium was studied. Two dispersing additives were examined in combination with two different carbon blacks, a conductive carbon black and a nonconductive one. These carbon blacks differ in the size of their aggregates and in the amounts of surface oxygen groups. Both of the additives form a monolayer when adsorbed on either of the pigment surfaces. FTIR studies showed that chemical bonding of one of the additives on the surfaces of both pigments had occurred. Conductivity decreases with increasing additive concentration, but in the case of the chemically bonded additive, the conductivity of the dispersion remained high even at higher additive loadings. This study helps in understanding the effects such additives have on the specific conductivity of composite materials that contain dispersed carbon black pigment particles. 相似文献
793.
Lizhen Chen Lars Klemeyer Mingbo Ruan Xin Liu Stefan Werner Weilin Xu Andrea Koeppen Robert Bücker Marta Gallego Gonzalez Dorota Koziej Wolfgang J. Parak Indranath Chakraborty 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(19):2206772
Nanozymes are nanomaterials with biocatalytic properties under physiological conditions and are one class of artificial enzymes to overcome the high cost and low stability of natural enzymes. However, surface ligands on nanomaterials will decrease the catalytic activity of the nanozymes by blocking the active sites. To address this limitation, ligand-free PtAg nanoclusters (NCs) are synthesized and applied as nanozymes for various enzyme-mimicking reactions. By taking advantage of the mutual interaction of zeolitic imidazolate frameworks (ZIF-8) and Pt precursors, a good dispersion of PtAg bimetal NCs with a diameter of 1.78 ± 0.1 nm is achieved with ZIF-8 as a template. The incorporation of PtAgNCs in the voids of ZIF-8 is confirmed with structural analysis using the atomic pair-distribution function and powder X-ray diffraction. Importantly, the PtAgNCs present good catalytic activity for various enzyme-mimicking reactions, including peroxidase-/catalase- and oxidase-like reactions. Further, this work compares the catalytic activity between PtAg NCs and PtAg nanoparticles with different compositions and finds that these two nanozymes present a converse dependency of Ag-loading on their activity. This study contributes to the field of nanozymes and presents a potential option to prepare ligand-free bimetal biocatalysts with sizes in the nanocluster regime. 相似文献
794.
795.
Radio Frequency IDentification (RFID) and related technologies such as Near Field Communication (NFC) are becoming essential in industrial contexts thanks to their ability to perform contactless data exchange, either device-to-device or tag-to-device. One of the three main operation modes of NFC, called read/write mode, makes use of the latter type of interaction. It is extensively used in business information systems that make use of NFC tags to provide the end-user with augmented information in one of several available NFC data exchange formats, such as plain text, simple URLs or enriched URLs. Using a wide variety of physical form factors, NFC-compatible tags (wireless transponders) are currently available in many locations with applications going from smart posters, contactless tokens, tap-and-go payments or transport ticketing to automated device configuration, patient identification at hospitals or inventory management within supply chains. Most of these applications handle sensitive processes or data. This paper proposes a complete security threat model for the read/write operation mode of NFC used in Next Generation Industrial IoT (Nx-IIoT) contexts. This model, based on a well-known methodology, STRIDE, allows developers and users to identify NFC applications vulnerabilities or weaknesses, analyze potential threats, propose risk management strategies, and design mitigation mechanisms to mention only some significant examples. 相似文献
796.
Luzhetskyy A Liu T Fedoryshyn M Ostash B Fedorenko V Rohr J Bechthold A 《Chembiochem : a European journal of chemical biology》2004,5(11):1567-1570
The glycosyltransferase gene lanGT3, involved in the biosynthesis of the angucyclic antibiotic landomycin A, has been characterised by targeted gene deletion. A lanGT3 mutant was shown to produce landomycin E, which consists of a trisaccharide side chain attached to the polyketide moiety. Expression of lanGT3 in the mutant restored landomycin A production. Our results indicate that LanGT3 is responsible for the transfer of the fourth sugar during landomycin A biosynthesis. 相似文献
797.
798.
Joana M. Ramis Javier Calvo Aina Matas Cristina Corbillo Antoni Gayà Marta Monjo 《Journal of materials science. Materials in medicine》2018,29(7):103
Osteoinductive capacity of demineralized bone matrix (DBM) is sometimes insufficient or shows high variability between different batches of DBM. Here, we tried to improve its osteoinductive activity by alkali-urea or trypsin treatment but this strategy was unsuccessful. Then, we tested the enrichment of DBM with a bone protein extract (BPE) containing osteogenic growth factors comparing two sources: cortical bone powder and DBM. The osteoinductive capacity (alkaline phosphatase activity) of the obtained BPEs was evaluated in vitro in C2C12 cells. Specific protein levels present in the different BPE was determined by enzyme-linked immunosorbent assay or by a multiplex assay. BPE from cortical bone powder showed a lack of osteoinductive effect, in agreement with the low content on osteoinductive factors. In contrast, BPE from DBM showed osteoinductive activity but also high variability among donors. Thus, we decided to enrich DBM with BPE obtained from a pool of DBM from different donors. Following this strategy, we achieved increased osteoinductive activity and lower variability among donors. In conclusion, the use of a BPE obtained from a pool of demineralized bone to enrich DBM could be used to increase its osteoinductive effect and normalize the differences between donors. 相似文献
799.
Gladys Rosario Ramos Yacasi Ana Cristina Calpena Campmany María Antonia Egea Gras Marta Espina García María Luisa García López 《Drug development and industrial pharmacy》2017,43(4):637-651
Context: The stabilization of flurbiprofen loaded poly-?-caprolactone nanoparticles (FB-P?CL-NPs) for ocular delivery under accurate freeze-drying (FD) process provides the basis for a large-scale production and its commercial development.Objective: Optimization of the FD to improve long-term stability of ocular administration’s FB-P?CL-NPs.Methods: FB-P?CL-NPs were prepared by solvent displacement method with poloxamer 188 (P188) as stabilizer. Freezing and primary drying (PD) were studied and optimized through freeze-thawing test and FD microscopy. Design of experiments was used to accurate secondary drying (SD) conditions and components concentration. Formulations were selected according to desired physicochemical properties. Furthermore, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to study interactions components.Results: Optimized FB-P?CL-NPs, stabilized with 3.5% (w/w) P188 and protected with 8% (w/w) poly(ethylene glycol), was submitted to precooling at +10?°C for 1?h, freezing at ?50?°C for 4?h, PD at +5?°C and 0.140 mbar for 24?h and a SD at +45?°C during 10?h. These conditions showed 188.4?±?1.3?nm, 0.087?±?0.014, 85.5?±?1.4%, 0.61?±?0.12%, ?16.4?±?0.1?mV and 325?±?7 mOsm/kg of average size, polydispersity index, entrapment efficiency, residual moisture, surface charge and osmolality, respectively. It performed a long-term stability >12 months. DSC and XRD spectra confirmed adequate chemical interaction between formulation components and showed a semi-crystalline state after FD.Conclusions: An optimal freeze dried ocular formulation was achieved. Evidently, the successful design of this promising colloidal system resulted from rational cooperation between a good formulation and the right conditions in the FD process. 相似文献
800.
Robin A. James Andrew J. Stapleton Adam Hughes Eric Charrault Kamil Zuber Eliza Switalska Drew Evans Peter Murphy Marta Llusca 《Advanced Engineering Materials》2018,20(7)