Label-Free Single Cell Viability Assay Using Laser Interference Microscopy

Laser interference microscopy (LIM) is a promising label-free method for single-cell research applicable to cell viability assessment in the studies of mammalian cells. This paper describes the development of a sensitive and reproducible method for assessing cell viability using LIM. The method, based on associated signal processing techniques, has been developed as a result of real-time investigation in phase thickness fluctuations of viable and non-viable MCF-7 cells, reflecting the presence and absence of their metabolic activity. As evinced by the values of the variable vc, this variable determines the viability of a cell only in the attached state (vc exceeds 20 nm2 for viable attached cells). The critical value of the power spectrum slope βc of the phase thickness fluctuations equals 1.00 for attached MCF-7 cells and 0.71 for suspended cells. The slope of the phase fluctuations’ power spectrum for MCF-7 cells was determined to exceed the threshold value of βc for a living cell, otherwise the cell is dead. The results evince the power spectrum slope as the most appropriate indicator of cell viability, while the integrated evaluation criterion (vc and βc values) can be used to assay the viability of attached cells.

Achieve flexible large-scale reactivity tuning by controlling phase, thickness and support of two-dimensional ZnO

Tuning surface reactivity of catalysts is an effective strategy to enhance catalytic activity towards a chemical reaction. Traditional reactivity tuning usually relies on a change of catalyst composition, especially when...

Method of spherical phase screens for the modeling of propagation of diverging beams in inhomogeneous media

The phase-screen (split-step) method is widely used for the modeling of wave propagation in inhomogeneous media. Most known is the method of flat phase screens. An optimized approach based on cylindrical phase screen was introduced for the 2-D modeling of radio occultation sounding of the Earth’s atmosphere. In this paper, we propose a further generalization of this method for the 3-D problem of propagation of diverging beams. Our generalization is based on spherical phase screens. In the paraxial approximation, we derive the formula for the vacuum screen- to-screen propagator. We also derive the expression for the phase thickness of a thin layer of an isotropic random media. We describe a numerical implementation of this method and give numerical examples of its application for the modeling of a diverging laser beam propagating on a 25 km long atmospheric path.

The use of the interference microscopy to study structural characteristics of cultured dermal fibroblasts

Rationale: The use of electron, nuclear power and confocal microscopy for the screening of biologically active compounds, medical products and express diagnostics of some diseases at the cell level is associated with laborand time-consuming sample preparation, which cannot exclude potential measurement errors and artifacts. The modulation interference microscopy does not have these disadvantages; it allows for non-invasive studies of cell structures, imaging with nanometer resolution and analysis of the optical properties of an object.Aim: To assess the potential of the interference microscopy in the evaluation of morphofunctional characteristics of in vitro mitomycin conditioned cultured cell nuclei (dermal fbroblasts taken as a model).Materials and methods: Native culture of human dermal fbroblasts of the 6th passage, grown on glass with mirror coating in the cell culture laboratory of the Institute of Experimental Medicine and Biotechnology of Samara State Medical University (Russia), was examined with a modulation interference microscope MIM-340 (JSC PA UOMZ, Russia). Changes over time in the structural characteristics of dermal fbroblast nuclei conditioned with mitomycin were evaluated. The control group included fbroblasts cultured in the same conditions on glass with mirror coating without mitomycin. Imaging with MIM-340 was done at three hours, one and four days after adding the cytostatic. The control group was assessed at the same time points.Results: We have shown that the cell culture grown on dielectric glasses does not differ in its morphofunctional characteristics from the culture grown on culture plastics. This proves the possibility to study the adhesive native culture using interference microscopy. We have found that the cells respond to a single mitomycin 0.04% exposure with a change to a globular shape and a sharp increase in the nuclear phase thickness (217.8 vs. 142.18 nm in the control group, p ≤ 0.05). Thereafter, the morphofunctional characteristics of the cells are restored, which is confrmed by the changes over time in the culture density, cell shape and size, and the phase thickness of the nucleus.Conclusion: The results obtained make it possible to recommend the method of modulation interference microscopy for evaluation of toxicity and biocompatibility of drugs, medical products and physical factors for diagnosis and treatment.

Design of First-Order 121.6 nm Minus Filters

The equivalent parameters function in Macleod software can be used to calculate the equivalent admittance and phase thickness of multilayers, even when the material is both absorbing and dispersive, and the incidence angle is non-zero. We utilized this software to design first-order 121.6 nm minus filters based on a lanthanum trifluoride (LaF3)/magnesium fluoride (MgF2) multilayer; a Gaussian-type target curve was also introduced into the design. Minus filters with bandwidths of 10 and 5 nm were obtained and had good visible light suppression and low side-lobe ripples. This designed filter will be fabricated for use in a Lyman-alpha coronagraph and imager installed in the Lyman-Alpha Solar Telescope, which will be launched by China in 2021.

MECHANICAL PROPERTIES OF Cu SURFACE IN THE LAMINATED STRUCTURE OF Cr-Cu COATINGS

A laminated structure of Cr-Cu coating was produced by electroplating on a carbon steel substrate. Two baths of chromium and copper electrolyte solutions were prepared to respectively deposit Cr and Cu as the first and second layer. The Cr was plated using the same plating time of 60 minutes, whereas Cu was deposit using plating time of 1 hour, 1.5 hours, 2 hours, 3 hours and 3.5 hours. The effect of plating time on the thickness, hardness and specific wear rate of the Cu surface was investigated. The formed phase, thickness, hardness and specific wear rate of the Cu surface were observed using XRD, optical microscope, Vickers microhardness tester and Ogoshi wear rate tester, respectively. The results show that Cu was formed on the surface. An increase of the Cu plating time increased the thickness and the specific wear rate of the Cu surface, but reduced the hardness of Cu surface. Cu layer was observed denser than that of Cr. This study showed that the use of Cu can be a potential candidate to laminate Cr for use in corrosive environment. Keywords