scholarly journals Non-invasive Chromatin Deformation and Measurement of Differential Mechanical Properties in the Nucleus

2021 ◽  
Author(s):  
Benjamin Seelbinder ◽  
Manavi Jain ◽  
Elena Erben ◽  
Sergei Klykov ◽  
Iliya D Stoev ◽  
...  
Keyword(s):  
High Resistance ◽  
Nuclear Organization ◽  
Temperature Gradients ◽  
Displacement Fields ◽  
Fluorescent Reporters ◽  
Non Invasive ◽  
Nuclear Compartments ◽  
Spatially Resolved ◽  
Resistance To Deformation ◽  
Strain Components

The nucleus is highly organized to facilitate coordinated gene transcription. Measuring the rheological properties of the nucleus and its sub-compartments will be crucial to understand the principles underlying nuclear organization. Here, we show that strongly localized temperature gradients (approaching 1°C /μm) can lead to substantial intra-nuclear chromatin displacements (>1 μm), while nuclear area and lamina shape remain unaffected. Using particle image velocimetry (PIV), intra-nuclear displacement fields can be calculated and converted into spatio-temporally resolved maps of various strain components. Using this approach, we show that chromatin displacements are highly reversible, indicating that elastic contributions are dominant in maintaining nuclear organization on the time scale of seconds. In genetically inverted nuclei, centrally compacted heterochromatin displays high resistance to deformation, giving a rigid, solid-like appearance. Correlating spatially resolved strain maps with fluorescent reporters in conventional interphase nuclei reveals that various nuclear compartments possess distinct mechanical identities. Surprisingly, both densely and loosely packed chromatin showed high resistance to deformation, compared to medium dense chromatin. Equally, nucleoli display particularly high rigidity and strong local anchoring to heterochromatin. Our results establish how localized temperature gradients can be used to drive nuclear compartments out of mechanical equilibrium to obtain spatial maps of their material responses.

Prediction of Creep Strain Relaxations in Biomaterials Using Differential Transformation Method

2018 ◽  
Vol 38 ◽  
pp. 11-22
Author(s):  
Olurotimi Adeleye ◽  
Augustine Eloka ◽  
Gbeminiyi Sobamowo
Keyword(s):  
Numerical Methods ◽  
High Resistance ◽  
Linear Models ◽  
Transformation Method ◽  
High Viscosity ◽  
Differential Transformation Method ◽  
Differential Transformation ◽  
Resistance To Deformation ◽  
Very High ◽  
Nonlinear Nature

The outcome of most implant failures is tragic. There is an increasing need to reduce the rate of implant failure. While there has been a lot of progress regarding this problem, a lot still needs to be done. The behaviour of biomaterials had been represented using linear models. Linear models failed to capture some certain behaviours in materials due to the nonlinear nature of biomaterials. More work has been done in an attempt to represent the deformation of these biomaterials using non-linear models, which realised success to a degree. However, providing accurate solutions to these models became a problem. Here, An efficient approximate analytical method, differential transformation method (DTM) is provided for prediction of biomaterial deformation. The results of the solutions are found to be in excellent agreements with the results of the numerical methods. It was observed that at high viscosity, the material exhibit very high resistance to deformation and as it decreases, the material allows more deformation, for longer periods of time.Keywords:Biomaterials; Viscoelasticity;deformation;DifferentialTransformation Method;

scholarly journals Linking Tissue Damage to Hyperspectral Reflectance for Non-Invasive Monitoring of Apple Fruit in Orchards

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 310
Author(s):  
Alexei Solovchenko ◽  
Alexei Dorokhov ◽  
Boris Shurygin ◽  
Alexandr Nikolenko ◽  
Vitaly Velichko ◽  
...  
Keyword(s):  
Apple Fruit ◽  
Individual Plant ◽  
Hyperspectral Reflectance ◽  
Non Invasive ◽  
Spatially Resolved ◽  
Reflected Light ◽  
Tissue Damages ◽  
Apple Cultivars ◽  
Controlled Illumination ◽  
Point Type

Reflected light carries ample information about the biochemical composition, tissue architecture, and physiological condition of plants. Recent technical progress has paved the way for affordable imaging hyperspectrometers (IH) providing spatially resolved spectral information on plants on different levels, from individual plant organs to communities. The extraction of sensible information from hyperspectral images is difficult due to inherent complexity of plant tissue and canopy optics, especially when recorded under ambient sunlight. We report on the changes in hyperspectral reflectance accompanying the accumulation of anthocyanins in healthy apple (cultivars Ligol, Gala, Golden Delicious) fruits as well as in fruits affected by pigment breakdown during sunscald development and phytopathogen attacks. The measurements made outdoors with a snapshot IH were compared with traditional “point-type” reflectance measured with a spectrophotometer under controlled illumination conditions. The spectra captured by the IH were suitable for processing using the approaches previously developed for “point-type” apple fruit and leaf reflectance spectra. The validity of this approach was tested by constructing a novel index mBRI (modified browning reflectance index) for detection of tissue damages on the background of the anthocyanin absorption. The index was suggested in the form of mBRI = (R640−1 + R800−1) − R678−1. Difficulties of the interpretation of fruit hyperspectral reflectance images recorded in situ are discussed with possible implications for plant physiology and precision horticulture practices.

scholarly journals Special Issue: Novel Methods for Labeling Nanomaterials for Biological and Environmental Tracing Radiolabeling of Nanomaterials: Advantages and Challenges

2021 ◽  
Vol 3 ◽  
Author(s):  
Wanqin Dai ◽  
Junzhe Zhang ◽  
Yun Wang ◽  
Chunlei Jiao ◽  
Zhuda Song ◽  
...  
Keyword(s):  
Real Time ◽  
High Reliability ◽  
High Sensitivity ◽  
Clinical Applications ◽  
Special Issue ◽  
Complex Samples ◽  
Non Invasive ◽  
Spatially Resolved ◽  
Toxicological Research ◽  
The Stability

Quantifying the distribution of nanomaterials in complex samples is of great significance to the toxicological research of nanomaterials as well as their clinical applications. Radiotracer technology is a powerful tool for biological and environmental tracing of nanomaterials because it has the advantages of high sensitivity and high reliability, and can be matched with some spatially resolved technologies for non-invasive, real-time detection. However, the radiolabeling operation of nanomaterials is relatively complicated, and fundamental studies on how to optimize the experimental procedures for the best radiolabeling of nanomaterials are still needed. This minireview looks back into the methods of radiolabeling of nanomaterials in previous work, and highlights the superiority of the “last-step” labeling strategy. At the same time, the problems existing in the stability test of radiolabeling and the suggestions for further improvement are also addressed.

Thermo-mechanical stress analysis of rotating fiber reinforced variable thickness disk

2021 ◽  
pp. 030932472110609
Author(s):  
Ömer Can Farukoğlu ◽  
İhsan Korkut
Keyword(s):  
Variable Thickness ◽  
Failure Criteria ◽  
Temperature Gradients ◽  
Fiber Reinforced ◽  
Displacement Fields ◽  
Disk Radius ◽  
Radial Temperature ◽  
Stress And Displacement Fields ◽  
Angular Velocities ◽  
Analytical Approaches

Circumferentially fiber reinforced composite disk, which has a variable thickness, is modeled via analytical approaches. The disk is subjected to rotation in traction free conditions and decreasing, constant, and increasing steady state radial temperature gradients along the disk radius. Limit angular velocities are calculated by operating Tsai-Wu and Norris failure indexes to the problem. Subsequently, these limit velocities are gradually decreased to examine the stress and displacement fields. Acquired results show that as the angular velocity drops, the effects of temperature gradients become more visible. At lower angular velocities, these gradients may even alter the stress field directions. Also, different failure criteria implementation may change the calculated limit velocities to a considerable degree. Therefore, the failure index should be chosen attentively to procure conservative results. In the investigation, the influence of disk geometry on the directional stresses is studied as well. Without further ado, it can be expressed that the geometry causes slight alterations in stresses and displacements.

scholarly journals Algorithm-improved high-speed and non-invasive confocal Raman imaging of 2D materials

2019 ◽  
Vol 7 (3) ◽  
pp. 620-628 ◽  
Author(s):  
Sachin Nair ◽  
Jun Gao ◽  
Qirong Yao ◽  
Michael H G Duits ◽  
Cees Otto ◽  
...  
Keyword(s):  
High Speed ◽  
2D Materials ◽  
Cost Effective ◽  
Raman Microscopy ◽  
Confocal Raman Microscopy ◽  
Non Invasive ◽  
Spatially Resolved ◽  
Art Works ◽  
Confocal Raman ◽  
Sample Damage

Abstract Confocal Raman microscopy is important for characterizing 2D materials, but its low throughput significantly hinders its applications. For metastable materials such as graphene oxide (GO), the low throughput is aggravated by the requirement of extremely low laser dose to avoid sample damage. Here we introduce algorithm-improved confocal Raman microscopy (ai-CRM), which increases the Raman scanning rate by one to two orders of magnitude with respect to state-of-the-art works for a variety of 2D materials. Meanwhile, GO can be imaged at a laser dose that is two to three orders of magnitude lower than previously reported, such that laser-induced variations of the material properties can be avoided. ai-CRM also enables fast and spatially resolved quantitative analysis, and is readily extended to 3D mapping of composite materials. Since ai-CRM is based on general mathematical principles, it is cost-effective, facile to implement and universally applicable to other hyperspectral imaging methods.

Sign in / Sign up

Export Citation Format

Share Document