A Pneumatic-based Mechanism for Inserting a Flexible Microprobe into the Brain

Insertion of flexible microprobes into the brain requires withstanding the compressive penetration force by the microprobes. To aid the insertion of the microprobes, most of the existing approaches employ pushing mechanisms to provide temporary stiffness increase for the microprobes to prevent buckling during insertion into the brain. However, increasing the microprobe stiffness may result in acute neural tissue damage during insertion. Moreover, any late or premature removal of the temporary stiffness after insertion may lead to further tissue damage due to brain micromotion, or inaccuracy in the microprobe positioning. In this study, a novel pneumatic-based insertion mechanism is proposed which simultaneously pulls and pushes a flexible microprobe towards the brain. As part of the brain penetration force in the proposed mechanism is supplied by the tensile force, the applied compressive force, which the microprobe must withstand during insertion, is lower compared to the existing approaches. Therefore, the microprobes with a critical buckling force less than the brain penetration force can be inserted into the brain without buckling. Since there is no need for temporary stiffness increment, the neural tissue damage during the microprobe insertion will be much lower compared to the existing insertion approaches. The pneumatic-based insertion mechanism is modelled analytically to investigate the effects of the microprobe configuration and the applied air pressure on the applied tensile and compressive forces to the microprobe. Next, finite element modelling is conducted, and its analysis results not only validate the analytical results but also confirm the efficiency of the mechanism.

APPARATUS AND METHOD FOR CALCULATING PENETRATION FORCE BY DROP WEIGHT IMPACT TECHNIQUE

Because of the limitations that are experienced when trying to perform Charpy and Izod impact tests, the drop weight impact test is preferred over the more conventional impact methods to determine whether the material is brittle or ductile. The drop weight impact technique indicates the conditions under which real-life components would be subject to impact loading. In this study, a drop-weight impact instrument has been designed and manufactured using a dropping weight which impacts the specimens, falls through a perpendicular guide tube with a high range of impact energy levels. Force - deformation and acceleration –time graphs, could be determined by using various sensor systems were installed to calculate the impactor's velocity and the magnitude of the impact force. Consequently, the energy absorption of different materials can be measured and the damage resistance could be indicated.

Mechanical properties of a female reproductive tract of a beetle and implications for penile penetration

Coevolution of male and female genitalia is widespread in animals. Nevertheless, few studies have examined the mechanics of genital interactions during mating. We characterized the mechanical properties of the elongated female genitalia, the spermathecal duct, of the small cassidine beetle, Cassida rubiginosa . The data were compared with the mechanical properties of the elongated male genitalia, the flagellum. We analysed the material distributions of the spermathecal duct using a microscopy technique, established a tensile test setup under a light microscope and conducted tensile tests. Diameter and tensile stiffness gradients were present along the spermathecal duct, but its Young's modulus and material distribution were more or less homogeneous. The results confirmed the hypothesis based on numerical simulations that the spermathecal duct is more rigid than the flagellum. In the study species, the penile penetration force is simply applied to the base of the hyper-elongated flagellum and conveyed along the flagellum to its tip. Considering this simple penetration mechanism, the relatively low flexibility of the spermathecal duct, compared to the flagellum, is likely to be essential for effective penetration of the flagellum.

Laminated textile composites – Problems with bonding layers and sewing

In this paper laminated composites with woven fabric on the front side, polyurethane foam (PU) in the middle and knitted fabric on the back side were analyzed. These materials are widely used in the automotive industry, medicine, protection activities and other groups of technical textiles Based on analyses and problems encountered in practice, the hypothesis was made that the speed of joining the components into a laminated composite influences the needle penetration force and finally the seam quality when sewing. Investigations were performed using three GB needle systems, two PU thicknesses (2 and 4 mm) and three joining speeds (30, 35 and 40 m/min). According to the results obtained, it can be concluded that higher joining speeds determine lower penetration forces. By systematic analysis of the sewing seam the deformation of laminated composites occur at stitch points, which is caused by hardened PU residues after the lamination of components to a composite. Heating the needle during sewing resulted in partial melting of PU and adhesion of needle to the material is penetrating through which means damage to the needle and seam. This negative occurrence is more pronounced at lower bonding speeds, for higher PU thickness and thicker needle. Based on the results obtained it can be claimed that bonding speed, polyurethane thickness (PU) as well as needle type affected the penetration forces of sewing and seam quality.

How head shape and substrate particle size affect fossorial locomotion in lizards

Granular substrates ranging from silt to gravel cover much of the Earth's land area, providing an important habitat for fossorial animals. Many of these animals use their heads to penetrate the substrate. Although there is considerable variation in head shape, how head shape affects fossorial locomotor performance in different granular substrates is poorly understood. Here, head shape variation for 152 species of fossorial lizards was quantified for head diameter, slope and pointiness of the snout. The force needed to penetrate different substrates was measured using 28 physical models spanning this evolved variation was constructed. Ten substrates were considered, ranging in particle size from 0.025 to 4mm in diameter and consisting of spherical or angular particles. Head shape evolved in a weakly correlated manner, with snouts that were gently sloped being blunter. There were also significant clade differences in head shape among fossorial lizards. Experiments with physical models showed that as head diameter increased, absolute penetration force increased but force normalized by cross-sectional area decreased. Penetration force decreased for snouts that tapered more gradually and were pointier. Larger and angular particles required higher penetration forces, although intermediate size spherical particles, consistent with coarse sand, required the lowest force. Particle size and head diameter effect were largest, indicating that fossorial burrowers should evolve narrow heads and bodies, and select relatively fine particles. However, variation in evolved head shapes and recorded penetration forces suggest that kinematics of fossorial movement are likely an important factor in explaining evolved diversity.

Performance and Meat Quality of Intrauterine Growth Restricted Pigs

Intrauterine growth restricted (IUGR) pigs are characterized by high perinatal mortality and dysfunction of internal organs, adipose, and muscle tissues. However, little is known about the post-weaning performance and meat quality of the IUGR pigs. The aim of this study was to compare normal pigs and pigs with IUGR from birth until slaughter, also with respect to their meat quality. Pigs with the IUGR achieved lower slaughter weight but did not differ significantly from normal pigs in terms of their meat content. The IUGR did not negatively affect the culinary quality of the obtained meat, including its content of basic chemical components and energy value, as well as hardness, chewiness, cohesiveness, elasticity, and penetration force. The meat of the IUGR pigs, when compared to the meat of normal pigs, was characterized by higher pH, lower EC (Electrical Conductivity) and drip loss; it was also tenderer and obtained higher scores in sensory evaluation of taste, smell, and general desirability. Therefore, such raw material can be appreciated by the consumers and can be used for the production of culinary portions similarly to the raw material obtained from normal pigs.

Edible coatings based on cassava starch, salicylic acid and essential oils for preservation of fresh-cut mango

Mango has a short shelf-life after harvesting. The use of edible coatings on the elaboration of minimally processed mango is an alternative for its commercialization. In the present work edible coatings based on chitosan, starch-salicylic acid and starch-cinnamaldehyde-thymol were applied to fresh cut-mango. Weight loss, soluble solids, titratable acidity, color and microbiological analyses were studied along storage for 12 days at 8 °C and 90% relative humidity. Titratable acidity was the highest for mangoes coated with chitosan and the lowest was for starch-salicylic acid coating. Regarding instrumental texture, fruit coated with chitosan showed a higher penetration force compared to fruit coated with starch and uncoated samples. Microbiological results showed that all coated mangoes inhibited growing of fungi and yeast whereas uncoated samples showed an increase of both microorganisms along 12 days of storage period.

Modeling of UV Disinfection Irradiation Installations Using Computer Graphics Programs

In connection with the appearance and spread of COVID-19, lighting equipment manufacturers have prepared product lines and marketing programs to promote irradiators for air disinfection for domestic and industrial needs. In this regard, the CIE issued an official request for the use of ultraviolet radiation to fight the spread of COVID-19. Nevertheless, the penetration force of ultraviolet rays is small. The action of rays is limited only to the surface of the irradiated object, and the method of calculating and simulating irradiators is based on obtaining normalized values of irradiation on the surface. However, the main goal of designing bactericidal systems is to distribute UV radiation uniformly in all directions of engineering designs, regardless of their type. However, now, there is no computer graphics program allows you to get the values of normalized values at each point in space to check the effectiveness of the bactericidal system. This article presents a new method for solving the problem of modeling irradiation installations with the ability to analyze the normalized values at each point of the volume of air being treated.