查看更多>>摘要：Aims: To evaluate the in vitro effect of different glucose concentrations and the time series in erythrocyte cell viability and morphology parameters. Methods: Different glucose concentrations were assessed, from a normal physiological glucose concentration (5 mM) to a diabetes scenario (100 mM). Cell viability was obtained by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. The erythrocyte morphology (diameter, height, and axial ratio) was assessed by scanning electron microscopy (SEM). Results: A significant decrease in cell viability was observed in erythrocytes with higher glucose concentration (100 mM). There was also a significant increase in the cells’ diameter and height exposed to 100 mM, vs. those cultured with 5, 20, and 45 mM glucose, but only at 24 and 48 h. When comparing the same glucose concentration by a time series, it was observed that erythrocytes from the culture with 45 and 100 mM of glucose had a significant continuous decrease (approximately -0.40 μm) in diameter and height (24, 48, and 72 h), but there was no difference in the axial ratio observed. Conclusion: Continuous exposure to high glucose concentrations in diabetes models produced less cell viability and changes in erythrocyte morphology (larger and scrambled cells), which in vivo might impact in microvascular complications.
查看更多>>摘要：Sedimentary rocks are known for their complex pore system with varying morphology due to intricate diagenetic processes. The present study demonstrates the applicability of image analysis in analysing and defining reservoir rock properties. Conventional techniques provide quantitative results but fail to give information about the internal microstructure of the rock. On the other hand, digital image techniques reveal the micro and macro-pore types and their connectivity across multiple scales. Hence, we performed the digital image analysis on Field Emission Scanning Electron Microscopy (FESEM) images of sandstone and carbonate samples collected from the upper Assam and Bombay offshore basins. FESEM derived image analysis was used exclusively due to its several unique features over contemporary techniques involving lesser data acquisition, simulation time and performing analysis even on a rock chip obtained while drilling the borehole. Porosity was evaluated based on the percentage of pores available within the image, and permeability was evaluated using the Kozeny-Carman equation. Further, we developed statistical equations to understand the existence of coherence amongst these parameters. Our study shows that we could determine both open and closed porosities by this method. In addition, there is an agreement between the conventional porosity measurement and image-derived porosity for most rock samples, especially for very low and high porosity. Further, this study highlights the importance of thresholding, an essential component in evaluating porosity using digital images. We propose that the methodology developed can accurately characterise reservoirs based on pore networks using high-resolution imaging techniques. The developed methodology may be adopted to promote best practices. Since we used digital images obtained from small chip size rock samples, this method is advantageous to quickly calculate the porosity and permeability from rock chips retrieved from the sieve shaker while drilling. Digital datasets extracted from this analysis will be helpful for reservoir description and characterisation based on image-derived petrophysical parameters.
查看更多>>摘要：Atomic force microscopy (AFM) is a kind of high-precision nanoscale instrument to measure the surface morphology of various samples. Nevertheless, the standard AFM scanning process takes a very long time to obtain high-resolution images. Compressive sensing (CS) can be used to achieve fast AFM imaging. But, the traditional CS-AFM imaging is difficult to balance the image quality of each local area, resulting in poor quality in the object area at low sampling rate. Therefore, a novel imaging scheme of adaptive CS-AFM is proposed. The fast scanning is first used to generate a low resolution image in a short time, and then bicubic interpolation is performed to obtain a high resolution image. Afterwards, an advanced detection algorithm is used to realize the accurate detection and positioning of the objects. Furthermore, the supplementary scanning is carried out to achieve adaptive sampling on the objects. After sampling, the measurement matrix corresponding to the measurement points is constructed. Finally, Total Variation Minimization by Augmented Lagrangian and Alternating Direction Algorithm (TVAL3) is used to reconstruct the whole AFM image. The imaging quality of the sample is analyzed and assessed by image evaluation metrics (PSNR and SSIM) and visual effect. Compared with two non-adaptive imaging schemes, the proposed scheme is characterized by high automation, short time, and high quality.
查看更多>>摘要：Calcium oxalate crystals were observed on the leaf epidermis of Agave potatorum surrounding the stomatal complex. Their morphology corresponded to the styloid type, and the chemical composition using EDS spectrum confirms calcium oxalate. A significantly higher abundance of crystals was observed on the adaxial leaf side in comparison with the abaxial side (p < 0.05). Crystals grew up in bundles in a range of 6–8 elements into idioblasts. A light microscope reveals that these crystals reflect part of the incident light. Cuticle from the abaxial leaf side was thicker and had a special structure formed by six papillae surrounding a larger central papilla, which was observed as star-like. This could be related to the evolutionary adaptation of this Agave species to drought stress conditions.
查看更多>>摘要：Al-5.8Mg-0.4Mn with minor alloying additions of Sc and Zr was investigated via electrochemical testing and nitric acid mass loss testing (NAMLT) in order to reveal the influence of Sc and Zr upon sensitization and intergranular corrosion. The Al-Mg-Mn alloys were also analysed using an electron probe microanalyzer, indicating that β-phase (Al3Mg2) was more likely to precipitate around rectangular or cubic Al6Mn particles. Results reveal that the strength and intergranular corrosion resistance of Al-5.8Mg-0.4Mn was improved by the combined addition of Sc and Zr. The Al3(Sc1-xZrx) dispersoids can lead to an alteration of the relative proportion of low angle grain boundaries, and lower volume fraction of β-phase was observed for Al-5.8Mg-0.4Mn-xSc-yZr relative to the Sc and Zr free alloy.
查看更多>>摘要：Mechanical properties and sintering behavior of additive-free and TiN-doped ZrB2 ceramics were studied. Reactive spark plasma sintering method was applied for manufacturing of ceramics at 1850 °C for 6 min under 40 MPa. The impact of TiN addition on the microstructure evaluation, densification, and mechanical feathers was investigated. A porous monolithic ZrB2 with a relative density of 76.5 % was manufactured, while the introduction of 5 wt% TiN resulted in enhancement of relative density to 93.1 %. The formation of (Zr,Ti)B2 solid solution and in-situ h-BN and ZrN phases was proven by microstructural assessments and X-ray diffractometry. Minimizing the grain growth and improving the densification, as the results of TiN addition, led to enhancement in mechanical properties. The values of bending strength, fracture toughness, and Vickers hardness boosted from 187.6 MPa, 1.9 MPa.m?, and 10.1 GPa for additive-free ZrB2 to 606.5 MPa, 4.5 MPa.m?, and 18.8 GPa for (Zr,Ti)B2–ZrN–BN composite.
查看更多>>摘要：Energy dispersive spectroscopy (EDS) experiments were carried out in the scanning electron microscope (SEM) on top of either stainless steel (SS), silicon or glass substrates covered with TiN nitride coatings. The nominal coating thicknesses were 0.43, 1.1, 2.1 and 3.0 μm. From the EDS spectra obtained, the ratio between the strongest peak coming from the substrate and the Tik peak, from the coating, was assessed at an increasing microscope accelerating voltage (V0) between 10 and 30 kV. This ratio is afterward called Intensity-ratio (IR). A methodology was developed for assessing the coating thickness from the experimental IR and the V0 by using Monte Carlo simulations of the dispersion of electrons inside the covered samples and the concomitant emission of characteristic X-ray photons. Three freeware Monte Carlo graphical user interfaces were used, and the predicted thicknesses were compared between them, namely Casino, MC-Xray and DTSA. At fixed V0, numerical simulations predict a mono-valued and smooth relationship between IR and coating thickness. Monte Carlo predictions on the coating thickness were compared with reference thicknesses independently assessed by cross-sectional micrographs obtained in the SEM. Absolute value of percentage discrepancy between the predicted and the reference thicknesses was lower than 30 %, wherein the lower the V0, the less accurate the predicted thickness. In general, none of the three pieces of software compared outperformed the others, although predicted thicknesses significantly varied between them. For V0 higher than 20 kV, 90 % of predicted thicknesses deviated less than 15 % from the reference value. Predicted thicknesses for TiN coatings onto Si substrates presented the largest discrepancy regarding reference values.
查看更多>>摘要：Detection of the spatial distribution and temporal evolution of an element in different chemical states is difficult in transmission electron microscopy. Here, taking the lithium element as an example, spatial and temporal distribution of different lithium-containing compounds could be revealed by using electron energy-loss spectroscopy (EELS) combined with the analysis method of non-negative matrix factorization (NMF), which is an algorithm that can accomplish the decomposition of high-dimensional data, especially the data which must be positive to implement its physical significance. NMF algorithms of different forms are adopted in this paper to tackle the problem. It is shown that two types of iteration methods, fast hierarchical alternating least squares (Fast-HALS) and spatial orthogonal (SO)-HALS provide decent NMF results on EELS datasets of lithium element. In particular, the low-loss and the core-loss regions of the EELS data are combined together in the process of NMF analysis, enabling better distinction of different chemical states. The above algorithms are recommended for the purpose of analyzing the EELS datasets containing different chemical states of lithium.
查看更多>>摘要：Although the key steps of tail regeneration in lizards are well understood, further investigations involving skinks can provide the field of regeneration research with additional information. In order to characterize the cytoarchitecture of tail regeneration in Scincella tsinlingensis, an endemic species in China, its histological events and growth trends are investigated. The rate of tail regeneration varies with the season: it proceeds faster in summer and autumn than it does in winter and spring. Tail regeneration of S. tsinlingensis is summarized as wound healing, blastema formation, cell differentiation and tail growth, which can be subdivided into seven stages. Wound healing following tail loss, begins with an obvious outgrowth undergoing re-epithelialization. Numerous proliferating mesenchymal-like cells aggregate near the distal end of the severed spinal cord to form the blastema. The expanding blastema is invaded by blood vessels, nerves and ependyma. A cartilaginous skeleton is formed around the ependymal tube and the muscle starts to differentiate. The keratinization of epidermis coincides with scale formation. Pigmentation eventually occurs in the regenerated tail. Tail regeneration in S. tsinlingensis is an epimorphic kind of regeneration that is also known as blastema-mediated. Structure and composition of the regenerated tail, including its cytoarchitecture, represent a conserved pattern of regeneration also known from other lizards.
NSTL
Elsevier