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排序方式: 共有416条查询结果,搜索用时 15 毫秒
401.
402.
Bhagwat S Singh H Athawale A Hannoyer B Jouen S Lefez B Kundaliya D Pasricha R Kulkarni S Ogale S 《Journal of nanoscience and nanotechnology》2007,7(12):4294-4302
We report on the synthesis of iron oxide nanoparticles below 100 degrees C by a simple chemical protocol. The uniqueness of the method lies in the use of Ferrous ammonium sulphate (in conjugation with FeCl3) which helps maintain the stability of Fe2+ state in the reaction sequence thereby controlling the phase formation. Hexamine was added as the stabilizer. The nanoparticles synthesized at three different temperatures viz, 5 degrees, 27 degrees, and 95 degrees C are characterized by several techniques. Generally, when a mixture of Fe3+ and Fe2+ is added to sodium hydroxide, alpha-Fe2O3 (the anti-ferromagnetic phase) is formed after the dehydration process of the hydroxide. In our case however, the phases formed at all the three temperatures were found to be ferro (ferri) magnetic, implying modification of the formation chemistry due to the specifics of our method. The nanoparticles synthesized at the lowest temperature exhibit magnetite phase, while increase in growth temperature to 95 degrees C leads to the maghemite phase. 相似文献
403.
Calmus ML Macksoud EE Tucker R Iozzo RV Lechner BE 《Reproduction (Cambridge, England)》2011,142(1):183-194
Preterm premature rupture of membranes is responsible for one-third of preterm births. Ehlers-Danlos syndrome (EDS) is associated with preterm premature rupture of membranes in humans. In particular, an EDS variant is caused by a genetic mutation resulting in abnormal secretion of biglycan and decorin, two small leucine-rich proteoglycans highly expressed in reproductive tissues. Because biglycan/decorin null mutant (Bgn(-/-)Dcn(-/-)) mice demonstrate phenotypic changes similar to EDS, we used this model to test whether either biglycan or decorin or both play a role in the attainment of successful term gestation. Wild-type biglycan null mutant, decorin null mutant, and biglycan/decorin null mutant pregnancies were assessed for the length of gestation, pup and placenta weight, and litter size. Quantitative real-time PCR was performed to measure biglycan and decorin gene expression, and immunohistochemistry was performed to assess protein expression in placenta and fetal membranes at embryonic days E12, E15, and E18. Bgn(-/-)Dcn(-/-) dams displayed preterm birth, whereas the possession of at least two biglycan or decorin wild-type alleles was protective of preterm birth. The number of Bgn(-/-)Dcn(-/-) pups was decreased at postnatal day P1 but not at E18. Biglycan and decorin were upregulated in the placenta in the absence of each other and were developmentally regulated in fetal membranes, suggesting that these two proteoglycans demonstrate genetic complementation and contribute to gestational success in a dose-dependent manner. Thus, the biglycan/decorin null mutant mouse is a model of genetically induced preterm birth and perinatal loss. This model presents novel targets for preventive or therapeutic manipulation of preterm birth. 相似文献
404.
Dorina M. Opris Martin Molberg Christian Walder Yee Song Ko Beatrice Fischer Frank A. Nüesch 《Advanced functional materials》2011,21(18):3531-3539
Several polydimethylsiloxane elastomers were developed and investigated regarding their potential use as materials in dielectric elastomer actuators (DEA). A hydroxyl end‐functionalized polydimethylsiloxane was reacted with different crosslinkers and the electromechanical properties of the resulting elastomers were investigated. The silicone showing the best actuation at the lowest electric field was further used as matrix and compounded with encapsulated conductive polyaniline particles. These composites have enhanced properties including increased strain at break, higher dielectric constant as well as, gratifyingly, breakdown fields higher than that of the matrix. One of the newly synthesized composites is compared to the commercially available acrylic foil VHB 4905 (3M) which is currently the most commonly used elastomer for DEA applications. It was found that this material has little hysteresis and can be activated at lower voltages compared to VHB 4905. For example, when the newly synthesized composite was 30% prestrained, a lateral actuation strain of about 12% at 40 V μm?1 was measured while half of this actuation strain at the same voltage was measured for VHB 4905 film that was 300% prestrained. It also survived more than 100 000 cycles at voltages which are close to the breakdown field. Such materials might find applications wherever small forces but large strains at low voltages are required, in, for example, tactile displays. 相似文献
405.
Silvia Trabattoni Luisa Raimondo Marcello Campione Daniele Braga Vincent C. Holmberg David J. Norris Massimo Moret Andrea Ciavatti Beatrice Fraboni Adele Sassella 《Advanced Materials Interfaces》2015,2(18)
Rubrene (RUB) is one of the most studied organic semiconductors because, in the orthorhombic single‐crystal phase, it exhibits a record exciton diffusion length and one of the highest charge carrier mobilities ever reported. Here, thin films of oriented crystalline RUB are successfully grown in vacuum on millimeter‐sized (010)‐β‐alanine (β‐ala) single crystals with a step‐growth protocol, exploiting organic epitaxy. The experimental characterization demonstrates that these RUB films grow in the orthorhombic polymorph with the (100)RUB plane in contact with the (010)β‐ala surface and with precise azimuthal orientations. A complementary study of the RUB(100)/β‐ala(010) interface, performed by computational simulations, confirms the epitaxial relations expected by considering the molecular scale corrugations of the surfaces. Moreover, thanks to the wide transparency region of β‐ala, the RUB absorption bands in the UV range are directly detected for the first time. Finally, removal of the water‐soluble substrate enables the integration of the films in field effect transistors as high quality active organic layers. The characteristics of such RUB‐based devices confirm the quality and versatility of epitaxial thin films for use in organic electronics. 相似文献
406.
Giulia Serrano Beatrice Bonanni Marco Di Giovannantonio Tomasz Kosmala Michael Schmid Ulrike Diebold Aldo Di Carlo Jun Cheng Joost VandeVondele Klaus Wandelt Claudio Goletti 《Advanced Materials Interfaces》2015,2(17)
The pivotal importance of TiO2 as a technological material involves most applications in an aqueous environment, but the single‐crystal TiO2/bulk‐water interfaces are almost completely unexplored, since up to date solid/liquid interfaces are more difficult to access than surfaces in ultrahigh vacuum (UHV). Only a few techniques (as scanning probe microscopy) offer the opportunity to explore these systems under realistic conditions. The rutile TiO2(110) surface immersed in high‐purity water is studied by in situ scanning tunneling microscopy. The large‐scale surface morphology as obtained after preparation under UHV conditions remains unchanged upon prolonged exposure to bulk water. Moreover, in contrast to UHV, atomically resolved images show a twofold periodicity along the [001] direction, indicative of an ordered structure resulting from the hydration layer. This is consistent with density‐functional theory based molecular dynamics simulations where neighboring interfacial molecules of the first water layer in contact with the bulk liquid form dimers. By contrast, this dimerization is not observed for a single adsorbed water monolayer, i.e., in the absence of bulk water. 相似文献
407.
Eva Rentschler Beatrice Kuschel Manuel Krewinkel Wolfgang Claaßen Claudia Glück Bo Jiang Wanmeng Mu Timo Stressler Lutz Fischer 《Food Analytical Methods》2016,9(8):2210-2222
The valuable lactose derivatives lactulose and epilactose can be derived from lactose either by the Lobry de Bruyn-Alberda van Ekenstein transformation during heat treatments or by enzymatic conversion using cellobiose 2-epimerases (EC 5.1.3.11). The chromatographic determination of lactose, lactulose, and epilactose in milk is challenging, due to the variable ratio of the three saccharides and their similar retention properties. In this work, a dual high-performance liquid chromatography (HPLC) analysis for the quantification of lactose, lactulose, and epilactose in milk samples was developed and validated. The samples originated from an enzymatic lactose conversion using the cellobiose 2-epimerase from Caldicellulosiruptor saccharolyticus. Application of this enzyme led to the formation of high lactulose concentrations (28.0 g/L) in milk. The dual HPLC analysis utilized a combination of two chromatographic separation techniques, configured in two parallel systems. After precolumn derivatization, the samples were analyzed as follows: Method 1 determined the concentration of lactose and epilactose using a C18 column with an ion-pair reagent as eluent, coupled with a UV detector. Method 2 determined the concentration of lactulose using a trimodal stationary phase (hydrophilic interaction, anion- and cation-exchange properties) with acetonitrile/ammonium formiate buffer as eluent, coupled with an evaporative light scattering detector. Both methods were validated in terms of linearity, precision and recovery. The revealing detection limits in the milk samples were 3.32 mg/L for lactose, 4.73 mg/L for epilactose and 139 mg/L for lactulose. The dual HPLC analysis presented allows accurate lactose, lactulose, and epilactose separation in complex food matrices such as milk. 相似文献
408.
Jéssica Rosso Motta Ivo Emilio da Cruz Jung Verônica Farina Azzolin Cibele Ferreira Teixeira Luiza Elizabete Braun Daniel Augusto De Oliveira Nerys Marco Aurélio Echart Motano Marta Maria Medeiros Frescura Duarte Ednea Aguiar Maia-Ribeiro Ivana Beatrice Mânica da Cruz Fernanda Barbisan 《Journal of Food Biochemistry》2021,45(2):e13596
409.
Beatrice Maranini Giovanni Ciancio Marcello Govoni 《International journal of molecular sciences》2021,22(24)
Adult-onset Still’s disease (AOSD) is a systemic inflammatory disease of unknown etiology. Recent studies have demonstrated that the hallmark of AOSD is a cytokine storm, which is characterized by the excessive production of interleukin (IL)-1, IL-6, IL-18, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ), suggesting how pro-inflammatory cytokines play an important role in the pathogenesis of this disease. Actually, a certain proportion of patients (around 17–32%) with severe clinical symptoms achieves only partial remission or is resistant to both first-line corticosteroids and second-line DMARDs. These patients are defined as refractory AOSD patients, requiring higher dosage glucocorticoids, longer treatment duration, or the simultaneous introduction of immunosuppressive drugs, further leading to AOSD relapses. In this narrative review, we will analyze the latest literature data to unravel potential pathogenetic factors associated with specific patterns of AOSD disease or relapses in order to identify biomarkers that may guide clinical decisions, eventually leading to new therapeutic options. 相似文献
410.