Faculty Opinions recommendation of The growth speed of microtubules with XMAP215-coated beads coupled to their ends is increased by tensile force.

AbstractIn the development of structural composites based on regenerated cellulose filaments, the physical and chemical interactions at the fibre-matrix interphase need to be fully understood. In the present study, continuous yarns and filaments of viscose (rayon) were treated with either polymeric diphenylmethane diisocyanate (pMDI) or a pMDI-based hardener for polyurethane resins. The effect of isocyanate treatment on mechanical yarn properties was evaluated in tensile tests. A significant decrease in tensile modulus, tensile force and elongation at break was found for treated samples. As revealed by size exclusion chromatography, isocyanate treatment resulted in a significantly reduced molecular weight of cellulose, presumably owing to hydrolytic cleavage caused by hydrochloric acid occurring as an impurity in pMDI. Yarn twist, fibre moisture content and, most significantly, the chemical composition of the isocyanate matrix were identified as critical process parameters strongly affecting the extent of reduction in mechanical performance. To cope with the problem of degradative reactions an additional step using calcium carbonate to trap hydrogen ions is proposed.

Download Full-text

Finite Plane Strain Bending under Tension of Isotropic and Kinematic Hardening Sheets

Materials ◽

10.3390/ma14051166 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1166

Author(s):

Stanislav Strashnov ◽

Sergei Alexandrov ◽

Lihui Lang

Keyword(s):

Plane Strain ◽

Kinematic Hardening ◽

Tensile Force ◽

Plastic Region ◽

Equivalent Plastic Strain ◽

Isotropic Hardening ◽

Finite Plane ◽

Present Solution ◽

Bending Under Tension ◽

Elastic Unloading

The present paper provides a semianalytic solution for finite plane strain bending under tension of an incompressible elastic/plastic sheet using a material model that combines isotropic and kinematic hardening. A numerical treatment is only necessary to solve transcendental equations and evaluate ordinary integrals. An arbitrary function of the equivalent plastic strain controls isotropic hardening, and Prager’s law describes kinematic hardening. In general, the sheet consists of one elastic and two plastic regions. The solution is valid if the size of each plastic region increases. Parameters involved in the constitutive equations determine which of the plastic regions reaches its maximum size. The thickness of the elastic region is quite narrow when the present solution breaks down. Elastic unloading is also considered. A numerical example illustrates the general solution assuming that the tensile force is given, including pure bending as a particular case. This numerical solution demonstrates a significant effect of the parameter involved in Prager’s law on the bending moment and the distribution of stresses at loading, but a small effect on the distribution of residual stresses after unloading. This parameter also affects the range of validity of the solution that predicts purely elastic unloading.

Download Full-text

Differences in Tibia Shape in Organically Reared Chicken Lines Measured by Means of Geometric Morphometrics

Animals ◽

10.3390/ani11010101 ◽

2021 ◽

Vol 11 (1) ◽

pp. 101

Author(s):

Domitilla Pulcini ◽

David Meo Zilio ◽

Francesco Cenci ◽

Cesare Castellini ◽

Monica Guarino Amato

Keyword(s):

Geometric Morphometrics ◽

Body Weight Gain ◽

Growth Speed ◽

Walking Ability ◽

Static Behavior ◽

Walking Behavior ◽

Organic Farm ◽

Genetic Types ◽

External Reference ◽

Slow Growing

In the present study, the conformation of the tibia of seven genetic lines of broilers was analyzed by Geometric Morphometrics and correlated to carcass weight and walking ability. The used chicken genetic lines were classified as fast, medium, or slow growing and ranked for their walking ability. Six chicken types were reared in an organic farm and slaughtered at 81 days of age while one slow-growing and highly walking line (Naked Neck) was reared in a commercial farm and used as external reference for moving activity and growth speed. A mixed landmarks and semi-landmarks model was applied to the study of tibia shape. Results of this study showed that: (i) body weight gain was positively correlated to the curvature of the antero-posterior axis of the tibia; (ii) the shape of the tibia and the active walking behavior were significantly correlated; (iii) walking and not-walking genetic lines could be discriminated in relation to the overall shape of the tibia; (iv) a prevalence of static behavior was correlated to a more pronounced curvature of the antero-posterior axis of the tibia. Results of this study revealed that the walking genetic types have a more functional and natural tibia conformation. This easy morphologic method for evaluating tibia shape could help to characterize the adaptability of genotypes to organic and outdoor rearing.

Download Full-text

Cable Tensile Forces Associated to Winch Design in Tethered Harvesting Operations: A Case Study from the Pacific North West

Forests ◽

10.3390/f12070827 ◽

2021 ◽

Vol 12 (7) ◽

pp. 827

Author(s):

Omar Mologni ◽

Eric D. T. Nance ◽

C. Kevin Lyons ◽

Luca Marchi ◽

Stefano Grigolato ◽

...

Keyword(s):

Endurance Limit ◽

Tensile Force ◽

Force Analysis ◽

North West ◽

The Pacific ◽

Work Tasks ◽

Tensile Forces ◽

System Activation ◽

The Impact

Cable tensile forces in winch-assist harvesting have been investigated in order to assess the safety concerns of the technology. However, the literature is lacking, particularly in regards to the impact of winch design. In this study, a Summit Winch Assist tethering a feller-director on ground slopes up to 77% was monitored for four days. The cable tensile forces were simultaneously recorded at the harvesting and anchor machine at a frequency of 100 Hz. Cameras and GNSS devices enabled a time study of the operations and the recording of machine positions. Winch functionality and design were disclosed by the manufacturer and used for the interpretation of the results. The cable tensile forces reached 296 kN at the harvesting machine and 260 kN at the anchor machine. The slow negotiation of obstacles while moving downhill recorded the highest peaks, mainly due to threshold settings of the winch in the brake system activation. Lower but significant peaks were also recorded during stationary work tasks. The peaks, however, were limited to a few events and never exceeded the endurance limit of the cable. Overall, the study confirmed recent findings in cable tensile force analysis of active winch-assist operations and provided evidence of the underlaying mechanisms that contribute to cable tensile forces.

Download Full-text

A novel concept for evaluation of biofilm adhesion strength by applying tensile force and shear force

Water Science & Technology ◽

10.2166/wst.1996.0552 ◽

1996 ◽

Vol 34 (5-6) ◽

pp. 201-211 ◽

Cited By ~ 16

Author(s):

Akiyoshi Ohashi ◽

Hideki Harada

Keyword(s):

Adhesion Strength ◽

Shear Force ◽

Growth Stage ◽

Open Channel ◽

Tensile Force ◽

Cavity Formation ◽

Channel Reactor ◽

Flat Surfaces ◽

Novel Concept ◽

Gravity Test

A novel methodology is proposed in this study to evaluate biofilm adhesion strength in two different ways: by measuring detached biomass caused by tensile force and by shear force. Tensile force was provided by centrifuging biofilm-attached plates installed on rotary tables. Shear force was provided by colliding biofilm-attached plates by gravity. Test biofilms consisting of denitrifiers were formed on the flat surfaces of square (25 cm2) plates that had been submerged in a rectangular open-channel reactor. The detachment tests revealed that, although biofilm adhesion strength was relatively high at the earlier growth stage, it drastically decreased at the later stage. The most weakened location toward biofilm depth was observed at the substratum surface, at which the adhesion strength by tensile force dropped from a several Pa to below 1 Pa as biofilms became aged. The adhesion strength by shear force was all the time more than 100 times as large as that by tensile force, even though having a similar behavior. The proportion of cavity, i.e., biofilm-absent area at the biofilm/substratum interface, increased as biofilms became mature. Cavity formation was strongly responsible for lessening the adhesion strength. It is suggested that biofilm slough-off is caused by the decline of adhesion strength by tensile force rather than by shear force.

Download Full-text

Evaluation of Commercial Ropes Applied as Artificial Tendons in Robotic Rehabilitation Orthoses

Applied Sciences ◽

10.3390/app10030920 ◽

2020 ◽

Vol 10 (3) ◽

pp. 920 ◽

Cited By ~ 2

Author(s):

Guilherme de Paula Rúbio ◽

Fernanda Márcia Rodrigues Martins Ferreira ◽

Fabrício Henrique de Lisboa Brandão ◽

Victor Flausino Machado ◽

Leandro Gonzaga Tonelli ◽

...

Keyword(s):

Tensile Force ◽

Permanent Deformation ◽

Hand Movements ◽

Clinical Test ◽

Robotic Rehabilitation ◽

Upper Limb Rehabilitation ◽

Direct Measurements ◽

Robotic Orthosis ◽

Design Selection ◽

Limb Rehabilitation

This study aims to present the design, selection and testing of commercial ropes (artificial tendons) used on robotic orthosis to perform the hand movements for stroke individuals over upper limb rehabilitation. It was determined the load applied in the rope would through direct measurements performed on four individuals after stroke using a bulb dynamometer. A tensile strength test was performed using eight commercial ropes in order to evaluate the maximum breaking force and select the most suitable to be used in this application. Finally, a pilot test was performed with a user of the device to ratify the effectiveness of the rope. The load on the cable was 12.38 kgf (121.4 N) in the stroke-affected hand, which is the maximum tensile force that the rope must to supports. Paragliding rope (DuPont™ Kevlar ® ) supporting a load of 250 N at a strain of 37 mm was selected. The clinical test proved the effectiveness of the rope, supporting the requested efforts, without presenting permanent deformation, effectively performing the participant’s finger opening.

Download Full-text

Numerical Analysis of the Perforated Steel Sheets Under Uni-Axial Tensile Force

Metals ◽

10.3390/met9060632 ◽

2019 ◽

Vol 9 (6) ◽

pp. 632 ◽

Cited By ~ 1

Author(s):

Ahmed M. Sayed

Keyword(s):

Load Capacity ◽

Tensile Force ◽

Three Dimensional ◽

Tensile Load ◽

Experimental Tests ◽

Strain Engineering ◽

Uniaxial Tensile ◽

Fe Model ◽

Stress Strain ◽

Steel Sheets

The perforated steel sheets have many uses, so they should be studied under the influence of the uniaxial tensile load. The presence of these holes in the steel sheets certainly affects the mechanical properties. This paper aims at studying the behavior of the stress-strain engineering relationships of the perforated steel sheets. To achieve this, the three-dimensional finite element (FE) model is mainly designed to investigate the effect of this condition. Experimental tests were carried out on solid specimens to be used in the test of model accuracy of the FE simulation. Simulation testing shows that the FE modeling revealed the ability to calculate the stress-strain engineering relationships of perforated steel sheets. It can be concluded that the effect of a perforated rhombus shape is greater than the others, and perforated square shape has no effect on the stress-strain engineering relationships. The efficiency of the perforated staggered or linearly distribution shapes with the actual net area on the applied loads has the opposite effect, as it reduces the load capacity for all types of perforated shapes. Despite the decrease in load capacity, it improves the properties of the steel sheets.

Download Full-text