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991.
Herrmann KH Schmidt S Kretz A Haenold R Krumbein I Metzler M Gaser C Witte OW Reichenbach JR 《Magma (New York, N.Y.)》2012,25(3):233-244
Object
To investigate the potential of a clinical 3 T scanner to perform MRI of small rodents.Materials and methods
Different dedicated small animal coils and several imaging sequences were evaluated to optimize image quality with respect to SNR, contrast and spatial resolution. As an application, optimal grey-white-matter contrast and resolution were investigated for rats. Furthermore, manganese-enhanced MRI was applied in mice with unilateral crush injury of the optic nerve to investigate coil performance on topographic mapping of the visual projection.Results
Differences in SNR and CNR up to factor 3 and more were observed between the investigated coils. The best grey-white matter contrast was achieved with a high resolution 3D T 2-weighted TSE (SPACE) sequence. Delineation of the retino-tectal projection and detection of defined visual pathway damage on the level of the optic nerve could be achieved by using a T 1-weighted, 3D gradient echo sequence with isotropic resolution of (0.2?mm)3.Conclusions
Experimental studies in small rodents requiring high spatial resolution can be performed by using a clinical 3 T scanner with appropriate dedicated coils. 相似文献992.
Elena Chugunova Gabriele Micheletti Dario Telese Carla Boga Daut Islamov Konstantin Usachev Alexander Burilov Alena Tulesinova Alexandra Voloshina Anna Lyubina Syumbelya Amerhanova Tatiana Gerasimova Aisylu Gilfanova Victor Syakaev 《International journal of molecular sciences》2021,22(14)
A series of novel hybrid compounds containing benzofuroxan and 2-aminothiazole moieties are synthesized via aromatic nucleophilic substitution reaction. Possible reaction pathways have been considered quantum-chemically, which allowed us to suggest the most probable products. The quantum chemical results have been proved by X-ray data on one compound belonging to the synthesized series. It was shown that the introduction of substituents to both the thiazole and amine moieties of the compounds under study strongly influences their UV/Vis spectra. Initial substances and obtained hybrid compounds have been tested in vitro as anticancer agents. Target compounds showed selectivity towards M-HeLa tumor cell lines and were found to be more active than starting benzofuroxan and aminothiazoles. Furthermore, they are considerably less toxic to normal liver cells compared to Tamoxifen. The mechanism of action of the studied compounds can be associated with the induction of apoptosis, which proceeds along the mitochondrial pathway. Thus, new hybrids of benzofuroxan are promising candidates for further development as anticancer agents. 相似文献
993.
Vanessa Marinosci Kuan Chen Nick G. J. Helthuis Wouter J. B. Grouve Erik G. de Vries Ningzhong Bao Remko Akkerman Matthijn B. de Rooij Liangyong Chu 《应用聚合物科学杂志》2024,141(1):e54764
This article reports the direct observation of the fracture of individual poly-ether-ketone-ketone (PEKK) spherulites. A single layer of PEKK spherulites was obtained by bonding a PEKK film in-between two sandblasted Ti alloy plates using an autoclave. The crack of an individual PEKK spherulite was achieved by opening the Ti/PEKK/Ti sandwich using a double cantilever beam test. The fracture morphology of the PEKK spherulite was characterized using scanning electron microscopy and atomic force microscopy. It was found that under tensile stress the crack of the individual spherulite propagates along the middle plane and crosses the nucleation core. This is due to the symmetric radial structure of the spherulite. Moreover, it was found that the fracture surface morphology at the core of the spherulite is strongly influenced by the local crystalline structure, which is anisotropic and determined by the initial nucleation growth direction. As a result, the area fraction experiencing plastic deformation during the fracture of PEKK spherulites at different orientations may vary by an order of 10. Our results show the important role of the initial nucleation growth direction on the mechanical properties of the polymer crystals and may provide a new approach to the design of high-performance polymer materials with tailored crystalline structures. 相似文献
994.
Alexandra Pulyalina Galina Polotskaya Mikhail Goikhman Irina Podeshvo Ludmila Kalyuzhnaya Mikhail Chislov Alexander Toikka 《应用聚合物科学杂志》2013,130(6):4024-4031
Poly(benz‐3,1‐oxazinone‐4) was prepared by thermal cyclization of its hydrolytically stable precursor polyamic acid. Both polymer and its precursor were investigated as membrane materials. Thermogravimetric analysis and contact angle measurements were carried out for characterization of peculiarity of membrane compositions and analysis of membrane surface. Pervaporation of water–isopropanol mixture was studied in the wide range of feed composition. To interpret the pervaporation transport properties of the membranes, swelling experiments were performed, kinetic curves of sorption and desorption were plotted, and basic sorption and diffusion parameters were analyzed. It was established that poly(benz‐3,1‐oxazinone‐4) membrane is extremely effective in dehydration of water–isopropanol mixture and shows high separation factor. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4024–4031, 2013 相似文献
995.
Vanessa Ito Funai Delba Nisi Cosme Melo Nádson Murilo Nascimento Lima Rubens Maciel Filho 《应用聚合物科学杂志》2013,127(4):2910-2921
This work presents an experimental design methodology combined with computational simulation to correlate the influence of operational conditions and reactants charge in the numeric average molecular weight (MWN) as well as on monomer conversion (XCL), for the hydrolytic polymerization of nylon‐6 in a semibatch reactor. It evaluated the reaction temperature, the pressure profile, and the proportion of reactants in the charge. Experimental design was used to screen the most statistically significant variables and to develop a reliable predictive model for each response. The combined use of the models can be applied for process optimization, by establishing MWN and maximum XCL as objective functions. Responses surface allowed the visualization of the responses behavior when changing the independent variables and therefore to identify the optimal tendencies. This work demonstrates that such methodology can be applied for optimization of complex processes like the hydrolytic polymerization of nylon‐6. This polymerization has many side reactions occurring at the same time, which are sensitive to different profiles of pressure and temperature that are applied. This evaluation is quite interesting as such profiles are necessary to perform the several polymerization steps and have a significant impact on product characteristics and therefore in its applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
996.
Abstract The extraction of HNO3, HClO4, H2SO4 and H3PO4 by 20% (v/v) TBP (0.73 M) in n‐octane was measured under identical conditions up to and beyond the critical point of third phase formation (Limiting Organic Concentration, or LOC condition). The data, together with those obtained previously for HCl, allowed us to establish the following lyotropic series of effectiveness with respect to third phase formation in the extraction of acids by TBP: HClO4>H2SO4>HCl>H3PO4>HNO3. This series correlates with the amount of water present into the organic phase at the point of phase splitting. This result reinforces the validity of the reverse micellar model developed previously for the extraction of metal salts by TBP. The measurements of LOC values as a function of temperature revealed major differences among the acid‐TBP systems investigated. For HClO4, the strong increase of the LOC value with increasing temperatures is accompanied by a large favorable entropy change. The opposite is true for HCl, while H2SO4 and H3PO4 represent intermediate cases. Measurements of the LOC values for the extraction of HClO4 by TBP dissolved in a series of diluents confirmed that topological parameters, such as the Connectivity Index, CI, are useful for predicting the critical condition for phase splitting in different diluents. Based on the linear correlation between LOC values for HClO4 and CI values of diluents, the effective Connectivity Index of the French nuclear reprocessing diluent, HTP, a complex mixture of highly branched alkanes, was determined. 相似文献
997.
Alain Le-bail Tzvetelin dessev Dominique LerayTiphaine Lucas Sylvia MarianiGiovanni Mottollese Vanessa Jury 《Journal of food engineering》2011,105(2):379-385
The effect of the amount of steam injection on selected bread characteristics were investigated using a deck oven (1 m2 internal surface). Baking was done at 200 °C for 20 min with steaming of 100, 200, 300, 400 and 500 ml. The temperature at center of the bread and the CO2 concentration in the oven have been measured during baking. Specific volume, moisture loss and crust crumb ratio were measured after baking.The heating rate between 35 and 55 °C was considered to compare the steaming conditions. For low steaming (100 and 200 ml), the heating rate was significantly higher (p < 0.05) than those at higher steaming (400-500 ml). The heating rate at 300 ml was between the 100-200 and 400-500 ml groups. This difference was attributed to the condensation of steam on the loaf for higher steaming, which in turns slows down the heating rate. The largest bread volume was obtained either for low or high steaming. However, tearing of the crust was observed for low steaming. The crust-crumb ratio was increasing with decreasing amount of steaming. The amount of CO2 released during baking was higher for the highest amount of steaming; however, this result was not statistically different except between 100 and 500 ml. This could be attributed to a slower heating rate which in turns favors the secondary production of CO2 during baking until thermal inactivation of CO2. 相似文献
998.
Christina Zeitz Ccile Mjcase Christelle Michiels Christel Condroyer Juliette Wohlschlegel Marine Foussard Aline Antonio Vanessa Dmontant Lisa Emmenegger Audrey Schalk Marion Neuill Elise Orhan Sbastien Augustin Crystel Bonnet Amrit Estivalet Frdric Blond Steven Blanchard Camille Andrieu Sandra Chantot-Bastaraud Thierry Lveillard Saddek Mohand-Saïd Jos-Alain Sahel Isabelle Audo 《International journal of molecular sciences》2021,22(15)
999.
Georg von Freymann Alexandra Ledermann Michael Thiel Isabelle Staude Sabine Essig Kurt Busch Martin Wegener 《Advanced functional materials》2010,20(7):1038-1052
Recent progress in direct laser writing of three‐dimensional (3D) polymer nanostructures for photonics is reviewed. This technology has reached a level of maturity at which it can be considered as the 3D analogue of planar electron‐beam lithography. Combined with atomic‐layer deposition and/or chemical‐vapor deposition of dielectrics—the 3D analogues of planar evaporation technologies, the 3D polymer templates can be converted or inverted into 3D high‐refractive‐index‐contrast nanostructures. Examples discussed in this review include positive and inverse 3D silicon‐based woodpile photonic crystals possessing complete photonic bandgaps, novel optical resonator designs within these structures, 3D chiral photonic crystals for polarization‐state manipulation, and 3D icosahedral photonic quasicrystals. The latter represent a particularly complex 3D nanostructure. 相似文献
1000.
The fire performance of light timber frame assemblies mainly depends on the protection provided by the cladding. A comprehensive
experimental and numerical analysis on the fire behaviour of protective cladding made of gypsum plasterboards and wood-based
panels has been recently carried out at ETH Zurich. The paper describes the main results of the experimental and numerical
analyses carried out with gypsum plasterboards. The results of the experimental and numerical analysis allowed the development
of a design model for the verification of the separating function (insulation and integrity criteria) of light timber frame
wall-and-floor assemblies. 相似文献