排序方式: 共有51条查询结果,搜索用时 15 毫秒
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Anastasiia Panfilova Sarah E. Shelton Cristina Caresio Ruud J.G. van Sloun Filippo Molinari Hessel Wijkstra Paul A. Dayton Massimo Mischi 《Ultrasound in medicine & biology》2019,45(2):539-548
Dynamic contrast-enhanced ultrasound (DCE-US) has been proposed as a powerful tool for cancer diagnosis by estimation of perfusion and dispersion parameters reflecting angiogenic vascular changes. This work was aimed at identifying which vascular features are reflected by the estimated perfusion and dispersion parameters through comparison with acoustic angiography (AA). AA is a high-resolution technique that allows quantification of vascular morphology. Three-dimensional AA and 2-D DCE-US bolus acquisitions were used to monitor the growth of fibrosarcoma tumors in nine rats. AA-derived vascular properties were analyzed along with DCE-US perfusion and dispersion to investigate the differences between tumor and control and their evolution in time. AA-derived microvascular density and DCE-US perfusion exhibited good agreement, confirmed by their spatial distributions. No vascular feature was correlated with dispersion. Yet, dispersion provided better cancer classification than perfusion. We therefore hypothesize that dispersion characterizes vessels that are smaller than those visible with AA. 相似文献
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Ivan D. Skurlov Anastasiia V. Sokolova Danila A. Tatarinov Peter S. Parfenov Danil A. Kurshanov Azat O. Ismagilov Aleksandra V. Koroleva Denis V. Danilov Evgeniy V. Zhizhin Sergey V. Mikushev Anton N. Tcypkin Anatoly V. Fedorov Aleksandr P. Litvin 《Materials》2022,15(21)
Lead halide perovskite nanoplatelets (NPls) attract significant attention due to their exceptional and tunable optical properties. Doping is a versatile strategy for modifying and improving the optical properties of colloidal nanostructures. However, the protocols for B-site doping have been rarely reported for 2D perovskite NPls. In this work, we investigated the post-synthetic treatment of CsPbBr3 NPls with different Cd2+ sources. We show that the interplay between Cd2+ precursor, NPl concentrations, and ligands determines the kinetics of the doping process. Optimization of the treatment allows for the boosting of linear and nonlinear optical properties of CsPbBr3 NPls via doping or/and surface passivation. At a moderate doping level, both the photoluminescence quantum yield and two-photon absorption cross section increase dramatically. The developed protocols of post-synthetic treatment with Cd2+ facilitate further utilization of perovskite NPls in nonlinear optics, photonics, and lightning. 相似文献
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The thermal properties, including the heat capacity, thermal conductivity, effusivity, diffusivity, and phonon density of states of silicon-based nanomaterials are analyzed using a molecular dynamics calculation. These quantities are calculated in more detail for bulk silicon, porous silicon, and a silicon aerocrystal (aerogel), including the passivation of the porous internal surfaces with hydrogen, hydroxide, and oxygen ions. It is found that the heat capacity of these materials increases monotonically by up to 30% with an increase in the area of the porous inner surface and upon its passivation with these ions. This phenomenon is explained by a shift of the phonon density of states of the materials under study to the low-frequency region. In addition, it is shown that the thermal conductivity of the investigated materials depends on the degree of their porosity and can be changed significantly upon the passivation of their inner surface with different ions. It is demonstrated that, in the various simulated types of porous silicon, the thermal conductivity changes by 1–2 orders of magnitude compared with the value for bulk silicon. At the same time, it is found that the nature of the passivation of the internal nanosilicon surfaces affects the thermal conductivity. For example, the passivation of the surfaces with hydrogen does not significantly change this parameter, whereas a passivation with oxygen ions reduces it by a factor of two on average, and passivation with hydroxyl ions increases the thermal conductivity by a factor of 2–3. Similar trends are observed for the thermal effusivities and diffusivities of all the types of nanoporous silicon under passivation, but, in that case, the changes are weaker (by a factor of 1.5–2). The ways of tuning the thermal properties of the new nanostructured materials are outlined, which is important for their application. 相似文献
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The universal thermo-mechanical processing including the interim long-term annealing together with forging for three 12% Cr martensitic steels with different alloying. This thermo-mechanical processing remarkably increases the impact toughness of these steels in wide temperature ranges and reduces the ductile-brittle transition temperature by 10–20 K. There is a 25 °C impact toughness of all 12% Cr steels subjected to the thermo-mechanical processing exceeds 60 J cm−2. Such an increment in impact toughness is accompanied with the significant changes in the structures of all 12% Cr steels with different alloying. The common feature for all 12% Cr steels subjected to the thermo-mechanical processing is found to be a noticeable decrease in delta-ferrite amount. In the steels containing Ta, the decrease in the mean size of prior austenite grains by 20–26% was revealed. For the 12% Cr steels with ultra-low N content, the thermo-mechanical processing provides the changes in the dispersion of M23C6 carbides and MX carbonitrides. 相似文献
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Nataliya V. Dolgushina Anastasiia G. Syrkasheva Nataliya P. Makarova Eugenia V. Kovalskaya Elena A. Kalinina Gennady T. Sukhikh 《Gynecological endocrinology》2015,31(10):61-64
AbstractPurpose: To evaluate the aneuploidy rates of 13, 18, and 21 and the X and Y chromosomes in embryos from patients with morphologically normal oocytes and different oocyte dysmorphisms.Methods: This prospective cohort study included 84 patients treated with in vitro fertilization (IVF) at a single academic center. The patients were divided into the following three groups: group 1 – women with cytoplasmic dysmorphisms (n?=?28), group 2 – women with extracytoplasmic dysmorphisms (n?=?28), and group 3 – women with morphologically normal oocytes (n?=?28). One blastomere from each embryo was analyzed for aneuploidies of chromosomes 13, 18, 21, X, and Y.Results: The highest prevalence of aneuploid embryos was observed in the group 1 (68.4%) followed by the group 2 (38.9%) and the group 3 (31.3%) (р?<?0.0001). The adjusted OR for receiving an aneuploid embryo in the case of cytoplasmic dysmorphism was 3.6 (95% CI?=?1.8; 7.2), in the case of extracytoplasmic dysmorphisms – 1.3 (95% CI?=?0.7; 2.1).Conclusions: Women with morphological oocyte abnormalities are at risk for developing aneuploid embryos during IVF cycles. We recommend that woman with cytoplasmic oocyte dysmorphisms receive additional genetic counseling to define the indications for the genetic screening of embryos. 相似文献
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Dominik Koszelewski Ryszard Ostaszewski Pawe
migielski Anastasiia Hrunyk Karol Kramkowski ukasz Laskowski Magdalena Laskowska Rafa Lizut Mateusz Szymczak Jacek Michalski Kamil Gawin Pawe Kowalczyk 《Materials》2021,14(18)
A preliminary study of 2-amino-4-aryl-3,5-dicarbonitrile-6-thiopyridines as new potential antimicrobial drugs was performed. Special emphasis was placed on the selection of the structure of target pyridine derivatives with the highest biological activity against different types of Gram-stained bacteria by lipopolysaccharide (LPS). Herein, Escherichia coli model strains K12 (without LPS in its structure) and R2–R4 (with different lengths of LPS in its structure) were used. Studied target compounds were provided with yields ranging from 53% to 91% by the lipase-catalyzed one pot multicomponent reaction of various aromatic aldehydes with malononitrile, and thiols. The presented work showed that the antibacterial activity of the studied pyridines depends on their structure and affects the LPS of bacteria. Moreover, the influence of the pyridines on bacteria possessing smooth and rough LPS and oxidative damage to plasmid DNA caused by investigated compounds was indicated. Additionally, the modification of the bacterial DNA with the tested compounds was performed to detect new potential oxidative damages, which are recognized by the Fpg protein. The obtained damage modification values of the analyzed compounds were compared with the modifications after antibiotics were used in this type of research. The presented studies demonstrate that 2-amino-4-aryl-3,5-dicarbonitrile-6-thiopyridines can be used as substitutes for known antibiotics. The observed results are especially important in the case of the increasing resistance of bacteria to various drugs and antibiotics. 相似文献
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Musa Khaitov Alexandra Nikonova Igor Shilovskiy Ksenia Kozhikhova Ilya Kofiadi Lyudmila Vishnyakova Alexander Nikolskii Pia Gattinger Valeria Kovchina Ekaterina Barvinskaia Kirill Yumashev Valeriy Smirnov Artem Maerle Ivan Kozlov Artem Shatilov Anastasiia Timofeeva Sergey Andreev Olesya Koloskova Nadezhda Kuznetsova Daria Vasina Maria Nikiforova Sergei Rybalkin Ilya Sergeev Dmitriy Trofimov Alexander Martynov Igor Berzin Vladimir Gushchin Aleksey Kovalchuk Sergei Borisevich Rudolf Valenta Rakhim Khaitov Veronica Skvortsova 《Allergy》2021,76(9):2840-2854