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31.
Jaakko Saari Fatima Siddique Sanna Korpela Elina Mntyl Teemu O. Ihalainen Katri Kaukinen Katriina Aalto-Setl Katri Lindfors Kati Juuti-Uusitalo 《International journal of molecular sciences》2022,23(3)
The small intestinal epithelium has an important role in nutrition, but also in drug absorption and metabolism. There are a few two-dimensional (2D) patient-derived induced pluripotent stem cell (iPSC)-based intestinal models enabling easy evaluation of transcellular transport. It is known that animal-derived components induce variation in the experimental outcomes. Therefore, we aimed to refine the differentiation protocol by using animal-free components. More specifically, we compared maturation of 2D-cultured iPCSs toward small intestinal epithelial cells when cultured either with or without serum, and either on Geltrex or on animal-free, recombinant laminin-based substrata. Differentiation status was characterized by qPCR, immunofluorescence imaging, and functionality assays. Our data suggest that differentiation toward definitive endoderm is more efficient without serum. Both collagen- and recombinant laminin-based coating supported differentiation of definitive endoderm, posterior definitive endoderm, and small intestinal epithelial cells from iPS-cells equally well. Small intestinal epithelial cells differentiated on recombinant laminin exhibited slightly more enterocyte specific cellular functionality than cells differentiated on Geltrex. Our data suggest that functional small intestinal epithelial cells can be generated from iPSCs in serum-free method on xeno-free substrata. This method is easily converted to an entirely xeno-free method. 相似文献
32.
The work makes use of the scanning vibrating electrode technique (SVET) and the scanning electrochemical microscope (SECM) to investigate microscopic aspects of the electrochemical reactions that occur in an iron-zinc galvanic couple immersed in aqueous sodium chloride solution. Detection of the corrosion processes was made by sensing the phenomena occurring in solution. The SVET provided information on the distribution of ionic currents arising from the metal surface, whereas the SECM measured the concentration of chemical species relevant to the corrosion processes. The two techniques had comparable sensitivity for the corrosion of iron but significant differences were observed concerning the detection of corrosion of zinc. 相似文献
33.
Investigating corrosion processes in the micrometric range: A SVET study of the galvanic corrosion of zinc coupled with iron 总被引:2,自引:0,他引:2
The galvanic corrosion of an iron/zinc pair immersed in aqueous 0.1 M Na2SO4 solution has been investigated by using the scanning vibrating electrode technique (SVET). In this way, investigations in the micrometer range of the progress of the electrochemical reactions involved in galvanic process were performed. The anodic oxidation process is observed to be initiated on the zinc sample in a localized manner, whereas the cathodic reaction involving the electroreduction of dissolved oxygen is homogeneously distributed over the iron sample. This later process is the rate determining step in the overall corrosion process, as demonstrated by the changes in the ionic and galvanic currents measured in the system when the area of the iron specimen is varied relative to that of zinc. The occurrence of coupled chemical reactions in the solution phase involving the products of the corrosion reactions could also be deduced from the integration of the ionic currents measured for each half-reaction during a SVET scan. Thus, the corrosion processes involved in the galvanic coupling of iron and zinc have been further understood by using this microelectrochemical technique appropriately, helping to better interpret large scale measurements. 相似文献
34.
S.A. Souza C.R.M. Afonso P.L. Ferrandini A.A. Coelho R. Caram 《Materials science & engineering. C, Materials for biological applications》2009,29(3):1023-1028
Titanium alloys present a combination of properties that makes them suitable materials for various medical applications, and there is special interest in Ti–Cu alloys for the fabrication of dental prostheses. The addition of Cu to Ti lowers the melting point of the alloy, as well as leading to the development of desirable mechanical properties. In this study a eutectoid alloy was prepared and heat treated, then cooled at various cooling rates. The eutectoid structure (α + Ti2Cu) was observed for all cooling rates used, and evidence of α′ martensite was found for cooling rate higher than 9 °C s–1. Lower cooling rates resulted in higher modulus values. This was attributed to the volume fraction of the α and Ti2Cu phases. Higher cooling rates produced structures with lower modulus values and greater hardness, a result attributed mainly to the development of a martensitic structure. 相似文献
35.
Bastos CC Fish PJ Vaz F 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1999,46(5):1201-1217
A new formulation for the Doppler signal generation process in pulsatile flow has been developed enabling easier identification and quantification of the mechanisms involved in spectral broadening and the development of a simple estimation formula for the measured rms spectral width. The accuracy of the estimation formula was tested by comparing it with the spectral widths found by using conventional spectral estimation on simulated Doppler signals from pulsatile flow. The influence of acceleration, sample volume size, and time window duration on the Doppler spectral width was investigated for flow with blunt and parabolic velocity profiles passing through Gaussian-shaped sample volumes. Our results show that, for short duration windows, the spectral width is dominated by window broadening and that acceleration has a small effect on the spectral width. For long duration windows, the effect of acceleration must be taken into account. The size of the sample volume affects the spectral width of the Doppler signal in two ways: by intrinsic broadening and by the range of velocities passing through it. These effects act in opposite directions. The simple spectral width estimation formula was shown to have excellent agreement with widths calculated using the model and indicates the potential for correcting not only for window and nonstationarity broadening but also for intrinsic broadening. 相似文献
36.
Antunes O.J. Bastos J.P.A. Sadowski N. Razek A. Santandrea L. Bouillault F. Rapetti F. 《IEEE transactions on magnetics》2006,42(4):599-602
In this work, we compare two nonconforming movement techniques: the mortar element method and the Lagrange multipliers. We present a unified formulation that can be easily used for electrical machines analysis. The anti-periodicity conditions as well as the use of high-order interface are discussed. The obtained linear systems are compared and results are shown for a permanent magnet machine. 相似文献
37.
Biosynthesis and stability of the mRNA population in DMSO-induced Friend erythroleukemic cells were studied after labeling the RNA with 3H-uridine and then chasing it with nonlabeled uridine. Globin RNA metabolism was studied by hybridization to excess complementary DNA convalently coupled to oligo(dT)-cellulose. After a labeling period of 120 min, 2-4% of the poly(A)-containing labeled RNA was in globin RNA; it decayed with a half-life of 16-17 hr. The rest of the poly(A)-containing RNA was composed to two kinetic populations: 85-90% decayed with a half-life of about 3 hr, while 10% decayed with a half-life of about 37 hr. The portion of globin RNA in labeled poly(A)-containing RNA behaved in an unexpected fashion during the chase period. During the initial chase period, the percentage of globin RNA increased rapidly, reaching a maximum of about 15% at 20 hr, but it subsequently declined gradually. Based on these findings, a model was built that describes the changes in the proportion of globin mRNA in poly(A)-containing RNA during continuous synthesis and after chase of the labeled RNA. It appears that if the parameters described remain constant during the maturation of erythroblasts, then this model would not account for the almost exclusive presence of globin RNA in the reticulocyte. By far the most effective way to achieve this high level of globin RNA is the destabilization of the mRNA population which is more stable than globin RNA, and not the stabilization of globin RNA itself. 相似文献
38.
Illustrations are given of non-ideal solutions of chemically reactive substances which display more than one equilibrium state, i.e. more than one relative minimum of Gibbs free energy. Simple cases are pairs of minima in symmetric regular solutions and unsymmetric Margules and van Laar solutions of two isomers in reactive equilibrium. The accessibility of the absolute minimum is discussed. Implications are pointed out for the general problem of calculating equilibrium states in non-ideal reaction systems. 相似文献
39.
Multiobjective optimization methodology for the development of the papermaking process is considered. The aim is to find efficient
and reliable solution procedures for the process line model consisting of sequential unit-process models; some of them based
on physics, whereas others on experimental data. By the consequence of modeling procedures, nonphysical states or inherited
from modeling data in statistical case, the unit-process models may suffer from undesired unreliability. To control the uncertainty
resulting from the unit-process models, a new multiobjective optimization approach is introduced where both the papermaking
targets as well as the uncertainty related unit-process models are simultaneously taken into account. We illustrate the solution
process by numerical examples related to the quality of the produced paper. 相似文献
40.
Isabel C.F.R. Ferreira Lillian Barros Maria Elisa Soares Maria Lourdes Bastos José Alberto Pereira 《Food chemistry》2007,103(1):188-195
Olive trees (Olea europaea L. Cv. Cobrançosa) from the northeast of Portugal were sprayed with three different copper formulations [bordeaux mixture (copper sulphate + calcium hydroxide − 20% Cu), copper hydroxide (40% Cu) and copper oxychloride (50% Cu)] to control olive fungal diseases. The residues of copper in olive leaves, harvested at different times, were evaluated by atomic absorption spectrometry. At all the collection times, treated olive leaves had significantly higher copper contents, compared to the control. The different copper amounts in pesticide formulations lowered the leaves contents in total phenols and hence their antioxidant properties. Olive leaves sprayed with copper oxychloride possessed the highest copper levels and the lowest content in phenols, which influenced its antioxidant activity (higher EC50 values for reducing power, scavenging effect on DPPH radicals and inhibition of erythrocyte hemolysis). Leaves without copper residues proved to be a good natural source of antioxidants, giving values comparable to the reference compounds. 相似文献