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

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.

The Role of the Non-Collagenous Extracellular Matrix in Tendon and Ligament Mechanical Behavior: A Review

Tendon is a connective tissue that transmits loads from muscle to bone, while ligament is a similar tissue that stabilizes joint articulation by connecting bone to bone. 70-90% of tendon and ligament's extracellular matrix (ECM) is composed of a hierarchical collagen structure that provides resistance to deformation primarily in the fiber direction, and the remaining fraction consists of a variety of non-collagenous proteins, proteoglycans, and glycosaminoglycans (GAGs) whose mechanical roles are not well characterized. ECM elements such as elastin, the proteoglycans decorin, biglycan, lumican, fibromodulin, lubricin, and aggrecan and their associated GAGs, and Cartilage Oligomeric Matrix Protein (COMP) have been suggested to contribute to tendon and ligament's characteristic quasi-static and viscoelastic mechanical behavior in tension, shear, and compression. The purpose of this review is to summarize existing literature regarding the contribution of the non-collagenous ECM to tendon and ligament mechanics, and to highlight key gaps in knowledge that future studies may address. Using insights from theoretical mechanics and biology, we discuss the role of the non-collagenous ECM in quasi-static and viscoelastic tensile, compressive, and shear behavior in the fiber direction and orthogonal to the fiber direction. We also address the efficacy of tools that are commonly used to assess these relationships, including enzymatic degradation, mouse knockout models, and computational models. Further work in this field will foster a better understanding of tendon and ligament damage and healing as well as inform strategies for tissue repair and regeneration.

Nonlinear Friction and Resistance, Generating Sources of Optimal Points in the Energy Field of Agricultural Aggregates Working Process

The paper presents a point of view on the main sources that can generate some optimal points in the energy field of the agricultural machines working processes. It looks like a possible source of the existence of optimal points in the energetic field of work processes of agricultural machinery and equipment, are the coefficients of friction and specific resistance to deformation of soil. In the news models these coefficients became nonlinear functions. Similar forms are given for all three coefficients and is shown the existence of optimal points. They make some considerations about this method and include results obtained using it.

Beyond muscles: Role of intramuscular connective tissue elasticity and passive stiffness in the octopus arm muscle function

The octopus arm is a ‘one of a kind’ muscular hydrostat, as demonstrated by its high maneuverability and complexity of motions. It is composed of a complex array of muscles and intramuscular connective tissue, allowing force and shape production. In this study, we investigated the organization of the intramuscular elastic fibers in two main muscles composing the arm bulk: the longitudinal (L) and the transverse (T) muscles. We assessed their contribution to the muscles’ passive elasticity and stiffness and inferred their possible roles in limb deformation. First, we performed confocal imaging of whole arm samples and provided evidence of a muscle-specific organization of elastic fibers (more chaotic and less coiled in T than in L). We next show that in an arm at rest, L muscles are maintained under 20% compression and T muscles under 30% stretching. Hence, tensional stresses are inherently present in the arm and affect the strain of elastic fibers. Because connective tissue in muscles is used to transmit stress and store elastic energy, we investigated the contribution of elastic fibers to passive forces using step-stretch and sinusoidal length-change protocols. We observed a higher viscoelasticity of L and a higher stiffness of T muscles, in line with their elastic fiber configurations. This suggests that L might be involved in energy storage and damping, while T in posture maintenance and resistance to deformation. The elastic fiber configuration thus supports the specific role of muscles during movement and may contribute to the mechanics, energetic and control of arm motion.

Damping Properties and Microstructure Analysis of Microbial Consolidated Rubber Sand

Up to now, there are few reports on the application of microbial-induced calcium carbonate precipitation (MICP) consolidated rubber sand. By means of uniaxial or cyclic loading test and SEM test, the consolidation effect of rubber sand samples with different rubber particle content after MICP consolidation is tested and analyzed. The results show that MICP is not affected by the amount of rubber particles; rubber particles improve the compressive strength and deformation ability of consolidated rubber sand samples and significantly enhance the damping ratio, resistance to deformation, and energy dissipation ability of consolidated rubber sand samples. Rubber sand after MICP consolidation is a good shock damping material. The conclusion of this paper provides reference data for the application of microbial-induced calcium carbonate precipitation consolidated rubber sand.

The nature and origin of cratons constrained by their surface geology

To the memory of Nicholas John (Nick) Archibald (1951−2014), master of cratonic geology. Cratons, defined by their resistance to deformation, are guardians of crustal and lithospheric material over billion-year time scales. Archean and Proterozoic rocks can be found in many places on earth, but not all of them represent cratonic areas. Some of these old terrains, inappropriately termed “cratons” by some, have been parts of mobile belts and have experienced widespread deformations in response to mantle-plume-generated thermal weakening, uplift and consequent extension and/or various plate boundary deformations well into the Phanerozoic. It is a common misconception that cratons consist only of metamorphosed crystalline rocks at their surface, as shown by the indiscriminate designation of them by many as “shields.” Our compilation shows that this conviction is not completely true. Some recent models argue that craton formation results from crustal thickening caused by shortening and subsequent removal of the upper crust by erosion. This process would expose a high-grade metamorphic crust at the surface, but greenschist-grade metamorphic rocks and even unmetamorphosed supracrustal sedimentary rocks are widespread on some cratonic surfaces today, showing that craton formation does not require total removal of the upper crust. Instead, the granulitization of the roots of arcs may have been responsible for weighing down the collided and thickened pieces and keeping their top surfaces usually near sea level. In this study, we review the nature and origin of cratons on four well-studied examples. The Superior Province (the Canadian Shield), the Barberton Mountain (Kaapvaal province, South Africa), and the Yilgarn province (Western Australia) show the diversity of rocks with different origin and metamorphic degree at their surface. These fairly extensive examples are chosen because they are typical. It would have been impractical to review the entire extant cratonic surfaces on earth today. We chose the inappropriately named North China “Craton” to discuss the requirements to be classified as a craton.

The Viscoelastic Behaviour of Waterlogged Archaeological Wood Treated with Methyltrimethoxysilane

Waterlogged wood treatment with methyltrimethoxysilane (MTMS) proved effective in stabilising wood dimensions upon drying (anti-shrink efficiency of 76–93%). Before the method can be proposed as a reliable conservation treatment, further research is required that includes the evaluation of the mechanical properties of treated wood. The aim of the study was to characterise the effect of the treatment on the viscoelastic behaviour of archaeological waterlogged elm and oak wood differing in the degree of degradation. Dynamic mechanical analysis in the temperature range from −150 to +150 °C was used for the study. To better understand the viscoelastic behaviour of the treated wood, pore structure and moisture properties were also investigated using Scanning Electron Microscopy, nitrogen sorption, and Dynamic Vapour Sorption. The results clearly show that methyltrimethoxysilane not only prevents collapse and distortions of the degraded cell walls and decreases wood hygroscopicity (by more than half for highly degraded wood), but also reinforces the mechanical strength by increasing stiffness and resistance to deformation for heavily degraded wood (with an increase in storage modulus). However, the MTMS also has a plasticising effect on treated wood, as observed in the increased value of loss modulus and introduction of a new tan δ peak). On the one hand, methyltrimethoxysilane reduces wood hygroscopicity that reflects in lower wood moisture content, thus limiting the plasticising effect of water on wood polymers, but on the other hand, as a polymer itself, it contributes to the viscous behaviour of the treated wood. Interestingly, the effect of silane differs with both the wood species and the degree of wood degradation.

Impact of Roasted Yellow Split Pea Flour on Dough Rheology and Quality of Fortified Wheat Breads

Roasted yellow split pea (YSP) flours were used to substitute wheat flour, at 10–20% (flour basis) in wheat bread formulations. Rheometry showed that roasted YSP flour addition increased elasticity and resistance to deformation and flow of the composite doughs, particularly at 20% substitution; instead, at 10% addition (either raw or roasted YSP flour), there were no effects on dough rheology and bread textural properties. Breads fortified with roasted YSP flour at levels >10% exhibited lower loaf-specific volume and harder crumb compared to control (bread without YSP flour). Moreover, only breads with 20% roasted YSP flour displayed a significantly higher staling extent and rate, compared to control, as assessed by large deformation mechanical testing and calorimetry (starch retrogradation) of crumb preparations. This formulation also showed a large increase in β-sheets and β-turns at the expense of α-helix and random coil conformations in protein secondary structure as assessed by FTIR spectroscopy. Roasting of YSP effectively masked the “beany” and “grass-like” off-flavors of raw YSP flour at 10% substitution. Overall, roasted YSP flour at the 10% level was successfully incorporated into wheat bread formulations without adversely affecting dough rheology, bread texture, and shelf-life, resulting in final products with a pleasant flavor profile.

Non-Newtonian Fluid Speed Breaker

Speed bumps, as traffic calming devices, have been extensively used to reduce traffic speed on local streets. This study represents a unique application of Non-Newtonian fluid as Speed Bump. This technical paper relates to a device that reduces the speed of any over speeding vehicles travelling on a roadway. It is formed by a flexible material which consist of Non-Newtonian fluid in it i.e. each receptacle is impregnated with a dilatants shear thickening fluid. The material is placed under compression during impact when the vehicle strikes it and the fluid itself acts as means for controlling the resistance to deformation of the strip. Thus, if the vehicle travels at a low speed the fluid has a low viscosity and the strip is easily deformed, whereas if the speed of the vehicle is high the viscosity of the fluid is high and as a result has great resistance to deformation, thus forming a rigid obstacle to the passage of the vehicle. Drivers must always slow down when driving over the conventional speed breakers to prevent damage to their vehicle. However, the Non-Newtonian fluid Speed Breaker is sensitive to the speed of the vehicle. The vehicle needs to slow down only if it is over speeding.

Improvement of subgrade soil by blending tyre driven aggregate (TDA)

Pavements are largely affected by the inherent variability of soil nature which may be change in type and condition. Subgrade soils are characterized by their resistance to deformation under load, which can be measured in terms of strength and stiffness. The subgrade strength of soil is the key factor to ensure the sustainability of the pavement and is considered as of prime importance for design of pavement. If pavements are constructed on weak subgrade soils, then there are chances of possible settlement and subsequent pavement failure. The aim of study is to improve the bearing pressure of existing subgrade soil using tyre driven aggregates obtained from scrap tyre. The California Bearing Ratio (CBR) tests were performed on existing subgrade soil and the improved soil with 5%, 15%, and 30% replacement of tyre driven aggregates. The maximum dry density of soil was found to be 1636 kg/m3 at optimum moisture content of 21.26%. The CBR of the existing ground was measured as 3.90%. It was revealed that CBR value was improved by 5.1%, 10% and 28.7% of existing value when subgrade grade soil was replaced by 5%, 15% and at 30% demolished aggregates, respectively