The basis of quality of sheep pelts and fur products is morphological features of the skin of sheep

The morphological and histological features of the skin and wool cover of sheep as the basis for the quality of fur sheep pelts have been studied. The most important properties of sheep pelts (uniformity, thinness and density of wool) are provide the possibility of producing high-quality fur semi-finished products from them. However, the features of the histostructure of fine-wool sheep determine the low mechanical strength of the “facial” layer of skin. As a result, the “front” layer during processing often cracks to the upper border of the reticular layer or even peels off from the latter, making the sheep pelt unsuitable for use on fur products. These defects in fur practice are called “cracking” and “peeling” of the facial layer. They are mainly peculiar to sheep pelts of fine-wooled sheep. In these animals due to the high density and tone of the coat, the roots and hair follicles, root vaginas, secretory departments, excretory ducts of the glands and other structures occupy a significant share of the volume in the thickness of the Pilar layer (up to 25–30 %). The share of fibrous structures remains less volume, and these structures themselves are relatively weakly developed, located loosely and loosely intertwined with each other. The accumulations of fat cells that occur here also cannot be attributed to skin-strengthening elements. In fine-fleece sheep the pilar layer is on average 60 % of the thickness of the dermis. Therefore, more than half of its thickness is a weakened zone. The strength of the “front” layer is not the same in different fine-wool breeds of sheep and in different animals within the breed. For example, the average breaking load for cod of the “front” layer in Soviet Merino pelts is 1,25 kg, and in Precoce is 2,49 kg.

Rapid growth of shear strain in weakened zones of the lithosphere

A weakened zone in the lithosphere plunging into the mantle can lead to an earthquake after the application of a shear stress only in the case if the effective viscosity of this zone is very low. At low viscosity, in the short time that elapses after the application of stress, significant displacements of the walls of the zone emerge causing high-amplitude seismic waves. The Andrade law describing the transient creep under constant stress applied at the initial time instant leads to very low effective viscosity a few first seconds after the initial time instant. The effective viscosity also decreases due to the temperature rise in the weakened zone caused by the dissipative release of heat. However, this process is not rapid enough to noticeably change the temperature and effective viscosity in a short time.

Modeling of large-deformation behaviour of marine sensitive clays and its application to submarine slope stability analysis

Post-slide investigations suggest that many large-scale submarine landslides occur through marine sensitive clay layers. A nonlinear mathematical model for post-peak degradation of undrained shear strength of sensitive clay is proposed based on experimental results. A method for estimation of model parameters is presented. Incorporating the model, an analytical solution is developed to examine possible mechanisms of large-scale submarine landslides. Analyses are performed for mild infinite slopes where the failure initiates from a “fully weakened zone” of soil having undrained shear strength lower than the shear stress acting parallel to the slope. The driving force, in excess of resistance, generated from the fully weakened zone is then transferred to the surrounding soil elements resulting in shear band formation due to strain-softening behaviour of sensitive clays. When the length of the fully weakened zone is greater than a critical length, catastrophic shear band propagation (self-driven without any additional external force) occurs, which could result in large-scale offshore landslides. A simple design chart is developed to calculate the critical length. Compared with a 2005 study by Puzrin and Germanovich based on a linear post-peak shear strength degradation model, the present study gives a conservative estimation of critical length for catastrophic shear band propagation.

Biological defleecing: intravenous infusion of amino acid mixtures lacking lysine and methionine creates a weakened zone in the wool staple, which is amenable to mechanical wool harvesting

Conventional shearing of sheep is labour-intensive, expensive and presents significant occupational health and safety risks. The only alternative at present is based on injection of epidermal growth factor, which severs the fibre at the follicle level. This technology cannot be used in pregnant animals and requires application of a net to retain the severed fleece. An alternative is to create a weakened zone within the wool staple, which would be sufficiently strong to retain the fleece on the sheep while a protective covering regrows, but sufficiently weak as to allow painless and automated removal of the fleece. We demonstrate that this approach is possible using mixtures of amino acids lacking lysine and methionine. Initially we demonstrate the relationships between staple strength, a subjective ‘harvestability’ score and a subjective ‘pain’ score, using fleeces from animals treated with varying levels of cortisol to create a wide range of strengths of wool attachment. We assigned a score to the ease with which we could manually break the staples, and also to the animal’s response to breaking the staples still attached to the skin. The relationships between these variables indicated that a staple was considered harvestable and could be removed with minimal skin flinch response at a staple strength of ~10–13 N/kTex. Staples within this range were then produced by intravenous infusion of mixtures of amino acids lacking in lysine and methionine for a 5-day period. The weak point was uniformly created across the entire fleece and when a prototype roller-pin device was applied to the weakened wool, it uniformly broke the fleece of the three sheep tested. The mode of action of the amino acid treatment on wool growth was studied. There was no effect of unbalanced amino acids on the rate of follicle bulb cell division, the number of active wool follicles, or the length of the keratinisation zone in the wool follicle. Fibre diameter was reduced by ~4 microns by treatment, and intrinsic fibre strength (strength relative to cross-sectional area of the wool fibres), was reduced by ~50%. Results of these trials are encouraging but further work is required to develop a practical, on-farm method of altering systemic amino acid supply and to design an automated, high-throughput system of severing the weakened wool.

Field Test Study of the Blast-Resistance Performance of Optimal Composite Anchorage Structure

This paper introduced the comparison test of new optimal composite anchorage structure and single anchorage structure. The measured results show that the particle acceleration of single anchorage structure is 2.22 times higher than that of the optimal composite anchorage structure. The dynamic strain of the former is 5.3~4.5 times higher than that of the latter. The blast-resistance of the optimal composite anchorage structure is 5.10 times higher than that of the single anchorage structure. Under the limit damage condition, the former is 4.13~3.40 higher than that of the latter. The optimal composite anchorage structure has excellent blast-resistance. Optimal weakened zone is between the reinforced support structure and the surround rock. Under the explosion condition, weakened zone is firstly deformed, cracked, crushed or densified, and at the same time, a great deal of blast energy is absorbed. Therefore, the crisis of the reinforced support structure is transferred into the weakened zone.