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排序方式: 共有993条查询结果,搜索用时 15 毫秒
961.
Konrad Walkowiak Sandra Paszkiewicz Izabela Irska Agnieszka Kochmanska Kamil Dydek Anna Boczkowska Rafal Stanik Mike Gude Amelia Linares Tiberio Ezquerra 《Advanced Engineering Materials》2023,25(13):2300046
Bionanocomposites based on poly(trimethylene 2,5-furandicarboxylate)-block-poly(tetramethylene oxide) (PTF-b-F-PTMO) with various contents of carbon nanofibers, graphene nanoplatelets and a hybrid system of these nanoparticles are synthesized via in situ polymerization. The dispersion of nanoparticles in the nanocomposites is determined using a scanning electron microscope and optical microscopy images. The thermal properties are studied employing differential scanning calorimetry, dynamic mechanical thermal analysis, and thermogravimetric analysis. The melt viscosity of the synthesized materials is determined using rheological measurements. Mechanical properties, along with the thermal and electrical conductivity, are also analyzed. The synthesized polymer nanocomposites are processed using injection molding and they display mechanical properties of elastomers during mechanical testing, which indicates that the obtained materials are, in fact, thermoplastic elastomers (TPE). Compared to a neat matrix (PTF-b-F-PTMO 50/50), the incorporation of nanoparticles causes an increase in the value of the degree of crystallinity and the value of the tensile modulus values (E) of the nanocomposites. Such reinforced bionanocomposites are especially interesting from an applicative point of view. They can be used as components of fuel systems, bumpers, or cupholders. 相似文献
962.
Rahul Madathiparambil Visalakshan Laura E. Gonzlez García Mercy R. Benzigar Arthur Ghazaryan Johanna Simon Agnieszka Mierczynska‐Vasilev Thomas D. Michl Ajayan Vinu Volker Mailnder Svenja Morsbach Katharina Landfester Krasimir Vasilev 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(25)
Nanoparticles have become an important utility in many areas of medical treatment such as targeted drug and treatment delivery as well as imaging and diagnostics. These advances require a complete understanding of nanoparticles' fate once placed in the body. Upon exposure to blood, proteins adsorb onto the nanoparticles surface and form a protein corona, which determines the particles' biological fate. This study reports on the protein corona formation from blood serum and plasma on spherical and rod‐shaped nanoparticles. These two types of mesoporous silica nanoparticles have identical chemistry, porosity, surface potential, and size in the y‐dimension, one being a sphere and the other a rod shape. The results show a significantly larger amount of protein attaching from both plasma and serum on the rod‐like particles compared to the spheres. Interrogation of the protein corona by liquid chromatography–mass spectrometry reveals shape‐dependent differences in the adsorption of immunoglobulins and albumin proteins from both plasma and serum. This study points to the need for taking nanoparticle shape into consideration because it can have a significant impact on the fate and therapeutic potential of nanoparticles when placed in the body. 相似文献
963.
Agnieszka Woosiak‐Hnat Krzysztof Zych Monika Myska Andrzej Kifonidis Maksymilian Dajworski Sawomir Lisiecki Artur Bartkowiak 《Packaging Technology and Science》2019,32(9):457-469
The iron compounds (iron(III) oxide‐hydroxide monohydrate FeO(OH) × H2O, iron(III) oxide Fe2O3, and ascorbic acid) were used as oxygen scavengers modifiers in laminating of polymer films. This oxygen‐scavenging system was coated on preselected films (low density polyethylene [LDPE] and polyethylene terephthalate [PET]) from which the laminates were formed. It presents the new form of composite material packaging that has the function of oxygen scavenging, which could be suitable for food packaging. The scope of the research included studies of morphology of oxygen scavengers by scanning electron microscope and their average particle size distribution measure by particle size analyzer, the effect of type, and concentration of these substances on viscosity of adhesive and seal strength of laminates. The Fourier‐transform infrared spectroscopy (FTIR) of laminates was also performed to observe the potential interaction of functional groups of polyurethane adhesives with oxygen scavenger components. The most important ability of the developed system for oxygen scavenging was confirmed by measuring oxygen concentration (% vol) in a headspace with the prepared laminates. The concentrations of selected oxygen scavengers (4‐6 wt%) and their combinations were studied. The most effective oxygen scavenger system integrated within the PE/PET composite film consists of 6 wt% ascorbic acid and 1 wt% FeO(OH) × H2O, where the oxygen concentration of 1.0 vol% (±0.20 vol%) was obtained after 15 days of storage. It was found that in this system the oxygen scavenging reaction occurs through ascorbate oxidation to dehydroascorbic acid, which is catalyzed by reduction of Fe3+ to Fe2+ ions. 相似文献
964.
Duplex Healing of Selectively Thiolated Guanosine Mismatches through a Cd2+ Chemical Stimulus
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Samantha M. L. Lunn Dr. Samira Hribesh Colette J. Whitfield Dr. Michael J. Hall Prof. Andrew Houlton Dr. Agnieszka K. Bronowska Dr. Eimer M. Tuite Dr. Andrew R. Pike 《Chembiochem : a European journal of chemical biology》2018,19(11):1115-1118
The on‐column selective conversion of guanosine to thioguanosine (tG) yields modified oligomers that exhibit destabilisation over the fully complementary duplex. Restoration to a stabilised duplex is induced through thio‐directed Cd2+ coordination; a route for healing DNA damage. Short oligomers are G‐specifically thiolated through a modified on‐column protocol without the need for costly thioguanosine phosphoramidites. Addition of Cd2+ ions to a duplex containing a highly disrupted tG central mismatch sequence, 3′‐A6tG4T6‐5′, suggests a (tG)8Cd2 central coordination regime, resulting in increased base stacking and duplex stability. Equilibrium molecular dynamic calculations support the hypothesis of metal‐induced healing of the thiolated duplex. The 2 nm displacement of the central tG mismatched region is dramatically reduced after the addition of a chemical stimuli, Cd2+ ions, returning to a minimized fluctuational state comparable to the unmodified fully complementary oligomer. 相似文献
965.
Materials Displaying Neural Growth Factor Gradients and Applications in Neural Differentiation of Embryoid Body Cells
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Bahman Delalat Agnieszka Mierczynska Soraya Rasi Ghaemi Alex Cavallaro Frances J. Harding Krasimir Vasilev Nicolas H. Voelcker 《Advanced functional materials》2015,25(18):2737-2744
The critical growth factor density required to support neural lineage generation from mouse embryonic stem cells is assessed by constructing a surface density gradient of immobilized nerve growth factor (NGF) from a plasma polymer film base. A chemical surface gradient varying from high hydroxyl group density to high aldehyde group density is prepared through diffusion‐controlled plasma polymerization of two monomers (ethanol and propionaldehyde) under a moving mask. NGF density gradients are then produced by reductive amination with the aldehyde groups on the plasma polymer surface. Mouse embryoid body derived (mEB) cell differentiation on the gradient surface is evaluated by immunofluorescence staining against Nestin. mEB cell density and the percentage of Nestin‐positive cells increase with increasing NGF density up to a critical value corresponding to 52.9 ng cm?2, above which cell attachment and differentiation do not increase further. This gradient‐based screening approach allows the growth factor surface densities to be optimized for biomaterials intended for cell differentiation or expansion, which is highly relevant to creating efficient manufacture processes for cell therapies. 相似文献
966.
Aleksandra Szydłowska‐Czerniak Agnieszka Tułodziecka 《Journal of the American Oil Chemists' Society》2014,91(12):2011-2019
Ultrasound‐assisted extraction (UAE) and conventional solid–liquid extraction were applied to extract total antioxidants from two rapeseed varieties. The antioxidant capacities (AC) of winter and spring rapeseed cultivars were determined by four different analytical methods: ferric reducing antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC), 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH), 2,2′‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS). The average AC of the studied rapeseed cultivars ranged between 4.21–10.03 mmol Trolox (TE)/100 g, 7.82–10.61 mmol TE/100 g, 8.11–51.59 mmol TE/100 g, 22.48–43.13 mmol TE/100 g for FRAP, CUPRAC, DPPH and ABTS methods, respectively. There are positive correlations between total phenolics (TPC = 804–1625 mg sinapic acid (SA)/100 g) and AC of the studied rapeseed extracts (r = 0.2650–0.9931). Results of the principal component analysis (PCA) indicate that there are differences between the total amounts of antioxidants in rapeseed samples extracted by different extraction techniques. Rapeseed extracts obtained after 18 min of ultrasonication revealed the highest content of total antioxidants. The UAE is a very useful, efficient and rapid technique of oilseed samples preparation for determination of AC by different analytical methods. 相似文献
967.
Two non-flammable electrolytes 1 M LiPF6 in sulfolane (TMS) + 5 wt% VC and 0.7 M lithium bis(trifluoromethanesulphonyl)imide (LiNTf2) in N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulphonyl)imide (MePrPyrNTf2) + 10 wt% gamma-butyrolactone (GBL) were tested with Li4Ti5O12 (LTO) as highly promising anode material for application in lithium-ion batteries. The results were compared for the titanium anode in the classic electrolyte: 1 M LiPF6 in propylene carbonate + dimethyl carbonate (PC + DMC, 1:1). The performances of LTO/electrolyte/Li cell were tested using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge and scanning electron microscopy (SEM). SEM images of electrodes and those taken after electrochemical cycling showed changes which may be interpreted as a result of solid-state interface formation. Good charge/discharge capacities and low capacity loss at medium C rates preliminary cycling was obtained for the Li4Ti5O12 anode. For LTO/1 M LiPF6 in PC + DMC/Li system, the best capacity was obtained at C/10 and C/3 (145 and 154 mAh g?1, respectively). In the case of a system working on the basis of a TMS solution (1 M LiPF6 in TMS + 5 wt% VC) the best value was obtained at a C/5 current and an average of more than 150 mAh g?1 (86 % of theoretical capacity). For the 0.7 M LiNTf2 in MePrPyrNTf2 + 10 wt% GBL electrolyte, the highest capacitance value (at C/20 current) of about 150 mAh g?1 was observed. The 1 M LiPF6 in TMS + 5 wt% VC and 0.7 M LiNTf2 in MePrPyrNTf2 + 10 wt% GBL electrolytes had a relatively broad thermal stability range and no decomposition peak was observed below 150 °C. 相似文献
968.
969.
We present some applications of the optical vortex birefringence compensator, based on the C polarization type singularities generated using two Wollaston compensators. The theory and experimental results of birefringent media properties measurements are presented. The possibility of the simultaneous measurement of both the azimuth angle and the phase retardance has been analyzed and experimentally verified. 相似文献
970.
A genomic screening approach to the structure-guided identification of drug candidates from natural sources 总被引:4,自引:0,他引:4
Hornung A Bertazzo M Dziarnowski A Schneider K Welzel K Wohlert SE Holzenkämpfer M Nicholson GJ Bechthold A Süssmuth RD Vente A Pelzer S 《Chembiochem : a European journal of chemical biology》2007,8(7):757-766
The potential of actinomycetes to produce natural products has been exploited for decades. Recent genomic sequence analyses have revealed a previously unrecognized biosynthetic potential and diversity. In order to rationally exploit this potential, we have developed a sequence-guided genetic screening strategy. In this "genome mining" approach, genes that encode tailoring enzymes from natural product biosyntheses pathways serve as indicator genes for the identification of strains that have the genetic potential to produce natural products of interest. We chose halogenases, which are known to be involved in the synthesis of halometabolites as representative examples. From PCR screening of 550 randomly selected actinomycetes strains, we identified 103 novel putative halogenase genes. A phylogenetic analysis of the corresponding putative halogenases, and the determination of their sequential context with mass spectrometric analysis of cultures filtrates revealed a distinct correlation between the sequence and secondary metabolite class of the halometabolite. The described screening strategy allows rapid access to novel natural products with predetermined structural properties. 相似文献