A modified resistance to compression (RtC) test for evaluation of natural fiber softness

Comfort is a key feature of any clothing that relates significantly to softness of the fiber, yarn and fabric from which is it constructed. A known softness assessment method for fibers is the resistance to compression test. This traditional test only provides a single force value for the resistance of a loose fiber sample using a fixed mass under compression. In this research, a modified resistance to compression test was introduced to show the effects of repeated compression, providing more information about the softness and resilience of selected fibers. Three different natural fiber types, including wool, cotton and alpaca were compared using this new approach. The results showed compression profiles were quite different for different fiber types as well as for the same fibers with different diameters. While the diameters of the wool and alpaca samples were similar (18.5 μm), the modified resistance to compression values were significantly higher for wool (with a peak value at 9.5 kPa compared to 2.1 kPa for alpaca). Cotton was different from wool and alpaca but showed a similar modified resistance to compression value (10.4 kPa) to wool. During cycles of compression, modified resistance to compression peak values decreased slightly and then tended to be constant. Even though the structures of wool, cotton and alpaca were quite different, there was no significant difference in the magnitude of decline in modified resistance to compression peak values. This means that the modified resistance to compression test is able to provide additional information on the resilience characteristics of different natural fibers, and can reveal the resistance behavior of fiber samples during cyclic compression.

Kinesin and Myosin Motors Compete to Drive Rich Multi-Phase Dynamics in Programmable Cytoskeletal Composites

The cytoskeleton of biological cells relies on a diverse population of motors, filaments, and binding proteins acting in concert to enable non-equilibrium processes ranging from mitosis to chemotaxis. The cytoskeleton’s versatile reconfigurability, programmed by interactions between its constituents, make it a foundational active matter platform. However, current active matter endeavors are limited largely to single force-generating components acting on a single substrate – far from the composite cytoskeleton in live cells. Here, we engineer actin-microtubule composites, driven by kinesin and myosin motors and tuned by crosslinkers, that restructure into diverse morphologies from interpenetrating filamentous networks to de-mixed amorphous clusters. Our Fourier analyses reveal that kinesin and myosin compete to delay kinesin-driven restructuring and suppress de-mixing and flow, while crosslinking accelerates reorganization and promotes actin-microtubule correlations. The phase space of non-equilibrium dynamics falls into three broad classes– slow reconfiguration, fast advective flow, and multi-mode ballistic dynamics – with structure-dynamics relations described by the relative contributions of elastic and dissipative responses to motor-generated forces.

Modeling of relative shear deformation zones before strong earthquakes in Kamchatka from 2018-2021

Представлено сравнительное моделирование зон относительных сдвиговых деформаций для четырех камчатских землетрясений с Mw ≥ 4.8, произошедших в период с декабря 2018 г. по март 2021 г., основанное на статической модели деформационного поля в рамках теории упругости. Земная кора рассмотрена как однородное изотропное упругое полупространство, в котором присутствуют различные источники напряжения, описывающие очаг землетрясения: точечный источник в виде единичной силы, точечный источник в виде комбинации девяти двойных сил, распределенный источник в виде прямоугольной площадки. We present a comparative modeling of the zones of relative shear deformation for four Kamchatka earthquakes Mw≥4.8 that occurred between December 2018 and March 2021. Modeling based on a static model of the deformation field in the framework of the theory of elasticity. The Earth’s crust is considered as a homogeneous isotropic elastic half-space, in which there are different sources of stress describing the source of the earthquake: a point source in the form of a single force, a point source in the form of a combination of nine double forces, a distributed source in the form of a rectangular area.

Influence of the Fractal Geometry on the Mechanical Resistance of Cantilever Beams Designed through Topology Optimization

In this work, the complex geometry of beams obtained from topology optimization is characterized through the fractal dimension (FD). The fractal dimension is employed as an efficiency measure of the mass distribution in the beams, that is, the capacity of the optimized solutions to be efficiently distributed in the design space. Furthermore, the possible relationships between the fractal dimension and beams’ mechanical properties are explored. First, a set of theoretical beams are studied based on their well-known fractal dimension. A 3D fractal called Menger sponge is reproduced on a Michell’s beam (cantilever with a single force applied at the end). The programming codes that generate those beams are created in Matlab software, as are the algorithms for estimating the fractal dimension (box-counting method). Subsequently, identical beams are modelled in the software Inspire in order to apply the topology optimization and determine the mechanical parameters from the static analysis. Results indicate that the fractal dimension is affected by the design geometry and proposed optimized solutions. In addition, several relationships among fractal dimension and some mechanical resistance parameters could be established. The obtained relations depended on the objectives that were initially defined in the topology optimization.

Indirect Measurement of Loading Forces with High-Speed Camera

In the last few decades, there has been a significant increase in interest in developing, constructing, and using structural health monitoring (SHM) systems. The classic monitoring system should, by definition, have, in addition to the diagnostic module, a module responsible for monitoring loads. These loads can be measured with piezoelectric force sensors or indirectly with strain gauges such as resistance strain gauges or FBG sensors. However, this is not always feasible due to how the force is applied or because sensors cannot be mounted. Therefore, methods for identifying excitation forces based on response measurements are often used. This approach is usually cheaper and easier to implement from the measurement side. However, in this approach, it is necessary to use a network of response sensors, whose installation and wiring can cause technological difficulties and modify the results for slender constructions. Moreover, many load identification methods require the use of multiple sensors to identify a single force history. Increasing the number of sensors recording responses improves the numerical conditioning of the method. The proposed article presents the use of contactless measurements carried out with the help of a high-speed camera to identify the forces exiting the object.

Identifying the Hot Spot Residues of the SARS-CoV-2 Main Protease Using MM-PBSA and Multiple Force Fields

In this study, we investigated the binding affinities between the main protease of SARS-CoV-2 virus and its various ligand to identify the hot spot residues of the protease. To investigate the effect of various force fields, we performed MD simulations with three different force fields: GROMOS54a7, Amber99-SB, and CHARMM36. The total amount of MD simulation time was 1.1 µs. To investigate how known ligands interact with Mpro of SARS-CoV-2, the binding affinities were calculated by using the MMPBSA approach. It is identified that no single force field succeeded in predicting the relative rankings of experimental binding affinities. When compared between different force fields, Amber99-SB and GROMOS54a7 results are fairly correlated while CHARMM36 results show weak or almost no correlations with the others. Additionally, we identified specific residues of Mpro, which contribute more importantly to the binding energies with ligands. It is identified that the residues of the S4 subsite of the binding site, N142, M165, and R188, contribute strongly to ligand binding. In addition, the terminal residues, D295, R298, and Q299 are identified to have attractive interactions with ligands via electrostatic and solvation energy. We believe that our findings will help facilitate develop novel inhibitors of SARS-CoV-2.

Morbid Vitalism

This essay frames Djuna Barnes’s 1936 novel Nightwood as an attempt to overcome an impasse between the discourses of hope and the discourses of despair in an interwar period in many ways preoccupied with questions of mortality. Synthesizing Decadent aesthetics and elements of Spinoza’s vitalist philosophy, Barnes produces a “morbid vitalism,” exemplified by Dr. Matthew O’Connor, by which life and death are conceived as variant expressions of a single force, and the subject is modeled as an assemblage of affects, impersonal but inherently social, that can be understood primarily through its pursuit of what Jack Halberstam has called “generative models of failure.” In exploring this mode of subjectivity, Barnes seeks to undermine a host of ostensible oppositions (hope and fear, ascendence and decadence, success and failure, morbidity and vitality), opening up a conceptual and affective space for thinking through—if not necessarily beyond—the ubiquity of despair in twentieth-century modernity. Ultimately, morbid vitalism points a way toward a broader conversation between life-oriented modernist scholarship on vitalism and affect, on the one hand, and ongoing inquiries into the relationship among death, Decadence, and modernism, on the other.

Influence of cutting parameters on mechanisms causing slug pulling

Shear cutting is one of the most widely used manufacturing processes in the production of sheet metal components. The reasons for this are the high output volume combined with low costs per part. The profitability of this process is significantly influenced by the lifetime of the active elements and the occurrence of unexpected process disturbances. While there are already many publications on the former, there are only few examinations on the wide spread process disturbance of slug pulling, which describes the phenomenon where the cut-out part is pulled upwards again during the punch return stroke. In particular, the different forces on the slug that cause this phenomenon have not yet been measured individually and independently of one another in one single tool. Thus, a shear cutting tool was developed that enables the measurement of the individual forces on the slug depending on various process parameters. Following, single stroke experiments were carried out to determine these forces and establish relationships between the process parameters, the characteristics of the slug and the measured forces. Finally, the interaction of all partial forces depending on selected process parameters is discussed in order to classify the relevance of every single force with regard to the occurrence of slug pulling. This understanding of the process is necessary in order to make a well-founded decision when designing future tools or selecting available remedial measures to avoid slug pulling.