In Vitro Magnetic Techniques for Investigating Cancer Progression

Worldwide, there are currently around 18.1 million new cancer cases and 9.6 million cancer deaths yearly. Although cancer diagnosis and treatment has improved greatly in the past several decades, a complete understanding of the complex interactions between cancer cells and the tumor microenvironment during primary tumor growth and metastatic expansion is still lacking. Several aspects of the metastatic cascade require in vitro investigation. This is because in vitro work allows for a reduced number of variables and an ability to gather real-time data of cell responses to precise stimuli, decoupling the complex environment surrounding in vivo experimentation. Breakthroughs in our understanding of cancer biology and mechanics through in vitro assays can lead to better-designed ex vivo precision medicine platforms and clinical therapeutics. Multiple techniques have been developed to imitate cancer cells in their primary or metastatic environments, such as spheroids in suspension, microfluidic systems, 3D bioprinting, and hydrogel embedding. Recently, magnetic-based in vitro platforms have been developed to improve the reproducibility of the cell geometries created, precisely move magnetized cell aggregates or fabricated scaffolding, and incorporate static or dynamic loading into the cell or its culture environment. Here, we will review the latest magnetic techniques utilized in these in vitro environments to improve our understanding of cancer cell interactions throughout the various stages of the metastatic cascade.

Effect of Co Substitution and Thermo-Magnetic Treatment on the Structure and Induced Magnetic Anisotropy of Fe84.5−xCoxNb5B8.5P2 Nanocrystalline Alloys

In the present work, we investigated in detail the thermal/crystallization behavior and magnetic properties of materials with Fe84.5-xCoxNb5B8.5P2 (x = 0, 5, 10, 15 and 20 at.%) composition. The amorphous ribbons were manufactured on a semi-industrial scale by the melt-spinning technique. The subsequent nanocrystallization processes were carried out under different conditions (with/without magnetic field). The comprehensive studies have been carried out using differential scanning calorimetry, X-ray diffractometry, transmission electron microscopy, hysteresis loop analyses, vibrating sample magnetometry and Mössbauer spectroscopy. Moreover, the frequency (up to 300 kHz) dependence of power losses and permeability at a magnetic induction up to 0.9 T was investigated. On the basis of some of the results obtained, we calculated the values of the activation energies and the induced magnetic anisotropies. The X-ray diffraction results confirm the surface crystallization effect previously observed for phosphorous-containing alloys. The in situ microscopic observations of crystallization describe this process in detail in accordance with the calorimetry results. Furthermore, the effect of Co content on the phase composition and the influence of annealing in an external magnetic field on magnetic properties, including the orientation of the magnetic spins, have been studied using various magnetic techniques. Finally, nanocrystalline Fe64.5Co20Nb5B8.5P2 cores were prepared after transverse thermo-magnetic heat treatment and installed in industrially available portable heating equipment.

Using rock magnetics to resolve composite magmatic state fabrics: a case study from the Younger Giant Dyke Complex, SW Greenland

<p>Understanding the geometry of magma chambers plays a critical role in determining the igneous petrogenic processes that occur as intrusions cool. Quantitative fabric analysis methods, such as anisotropy of magnetic susceptibility (AMS), are routinely used to measure magma flow dynamics and determine the mechanism of magma transport and emplacement. However, magma mushes typically experience multiple flow events; e.g. emplacement, convection, and interstitial melt percolation. There is thus a need to develop a more a sophisticated approach to unravelling complex rock fabrics that record more than one magmatic state process. This study uses novel rock magnetic datasets to untangle the evolution of the 1163 Ma Younger Giant Dyke Complex (YGDC) of SW Greenland, a multi-sheeted troctolite dyke system that attains widths up to 800 m and encloses several evolved and/or modally layered ovoid pods.</p><p>Field results identify that ovoid pods occur in the thickest dyke segments. Several pods are defined by gently inward dipping modal layers and/or a parallel mineral foliations, and in-phase AMS magnetic foliations lie parallel to the observed field fabrics. Critically, imbricated plagioclase crystals record a magma transport direction toward the center of each pod, and this observation is substantiated by in-phase AMS lineations that plunge down dip of the foliation and shallow toward the center of each pod. These observations are interpreted to show gravitational settling under a convective flow regime.</p><p>In addition, 66% of out-of-phase AMS fabrics are non-parallel with in-phase AMS results. Out-of-phase AMS is a relatively new technique and is thought to reflect anisotropy controlled by a restrictive group of ferromagnetic minerals such as single domain magnetite and pyrrhotite. Out-of-phase lineations in layered pods are relatively steeply inclined and do not shallow towards the center, we therefore hypothesize that these lineations record a late stage filter-pressing process within the crystal mush. To test this hypothesis, anisotropy of anhysteretic remanent magnetism (AARM) data were collected from 15 samples. Results show that the AARM and out-of-phase AMS tensor axes are parallel, indicating that the sub-fabric detected by out-of-phase AMS is normal and most likely controlled by single domain magnetite.</p><p>Our results show that the application of rock magnetic techniques is effective in unravelling magma convection fabrics from later melt migration fabrics in mushy magmas.</p>

The magnetic properties of natural pigments: preliminary analyses for their identification in Fine Arts

<p>A multidisciplinary approach, including compositional, spectroscopic and microscopic methodologies, is often used for the analysis and identification of pigments in Fine Arts. Although a large part of widely used natural and synthetic pigments contain Fe-oxides and hydroxides, their magnetic characterization is still poorly explored. The application of rock magnetism analyses through fast, cheap and non-destructive measurements, can be instead useful for the identification and discrimination of pigments through their distinctive magnetic properties.</p><p>In this preliminary study, the magnetic properties of several iron-based commercial pigments together with paintings models and supports, were analyzed.</p><p>In order to investigate the compositional differences of pigments by means of their magnetic behavior, the magnetic susceptibility, the hysteresis properties and the magnetic susceptibility variation at low and high temperature were measured on selected samples.</p><p>All the pigments showed different magnetic properties, mainly related to variable proportions of magnetite, hematite and maghemite as the main magnetic carriers.</p><p>Further studies will be addressed to define a protocol for applying the magnetic techniques to the characterization of pigments, including tests on samples produced by different brands and different periods, with the final aim of integrating the magnetic measurements with the different spectroscopic techniques commonly employed for the preservation and the analysis of cultural heritage.</p>

All-in-one rheology of multicellular aggregates

Tissues are generally subjected to external stresses, a potential stimulus for their differentiation or remodelling. While single-cell rheology has been extensively studied, mechanical tissue behavior under external stress is still poorly known because of a lack of adapted set-ups. Herein we introduce magnetic techniques designed both to form aggregates of controlled size, shape and content (magnetic molding) and to deform them under controlled applied stresses over a wide range of timescales and amplitudes (magnetic rheometer). We explore the rheology of multicellular aggregates (F9 cells) using both standard assays (creep and oscillatory response) and an innovative broad spectrum solicitation coupled with inference analysis. We find that multicellular aggregates exhibit a power-law response with non-linearities leading to tissue stiffening at high stress. Comparing magnetic measurements on aggregates to isolated F9 cells characterization by parallel-plates rheometry, we reveal the role of cell-cell adhesions in tissue mechanics. Thanks to its versatility, the magnetic rheometer thus stands as an essential tool to investigate model tissue rheology.

Structure-Property Relation in Varieties of Millets Grown in Karnataka

Aim: This study aims to establish structure-property relation of the varieties of millets grown in Karnataka. Study Design: Seven different varieties of millets were collected from the farms in Chitradurga district from the state of Karnataka in India. Place and Duration of Study: This study was conducted between January and April 2020 at the Vijnana Bhavan, University with Potential for excellence, University of Mysore, Karnataka Methodology: Magnetic property and characterization for seven out of the nine varieties of millets grown in Chitradurga, Hiriyur and Khandenahalli of Karnataka were carried out using X-ray diffraction studies (XRD), Energy Dispersive X-ray analysis (EDAX), Raman spectroscopy, SEM and Xplore AC magnetic techniques to understand the physical properties of these samples and to find out the structure-property relation in these millets. Results: The Foxtail millet is unique in terms of crystallites size, elemental distribution and magnetic properties. The structure-property relation of all the millets is determined. Conclusion: It is evident from these studies that all the millets are diamagnetic in nature, crystalline like order is less and the major component in all these millets is cellulose. Also the Foxtail millet has excellent structure-property relation.

A Methodology Based on Magnetic Susceptibility to Characterize Copper Mine Tailings

This paper intends to validate the application of magnetic techniques, particularly magnetic susceptibility, as sampling tools on a copper tailings terrace, by correlating them analytically. Magnetic susceptibility was measured in both the field and laboratory. Data obtained allowed for designing spatial magnetic susceptibility distribution maps, showing the horizontal variation of the tailings. In addition, boxplots were used to show the variation of magnetic susceptibility and the concentration of the elements analyzed at different depths of the copper tailings terrace. The degree of correlation between magnetic and chemical variables was defined with coefficient R2. The horizontal and vertical variations of magnetic susceptibility, the concentration of elements, and the significant correlations between them show a relationship between magnetic susceptibility and the chemical processes occurring in the tailing management facility, such as pyrite oxidation. Thus, the correlation functions obtained could be used as semiquantitative tools to characterize tailings or other mining residues.