Objectives This study aimed to investigate the effects of chronic restraint stress on the osseointegration of titanium implants. Materials and Methods Twenty adult male Wistar albino rats were used in the study. After surgical insertion of titanium implants into the metaphyseal part of the tibial bone, rats were randomly divided into two groups: a control group (CNT group) and an experimental restraint stress group (RS group). In the CNT group, titanium implants were inserted surgically, and rats received no further treatment during the 47-day experimental period. In the RS group, restraint stress was applied for 3 hours per day for 45 days, beginning 2 days after implant surgery. Weight of the rats was measured prior to surgery and at the end of the study to analyze the effects of stress. At the end of the experimental period, rats were euthanized, and implants and surrounding bone tissues were used for undecalcified histological analysis. Serum cortisol levels were assessed in cardiac blood samples from the rats following centrifugation. Results Average weight of rats in the RS group was lower than that of rats in the CNT group after the experimental protocol had been completed ( P <0.05). Further, serum cortisol levels were higher in the RS group than in the CNT group ( P <0.05). There were no significant differences in bone-implant connection levels between the two groups ( P >0.05). Conclusion The data analyzed in this study suggest that chronic restraint stress did not adversely affect rats during a 45-day osseointegration period.
It is known that shear thickening fluids increase the energy absorption capacity of high performance fabrics. For this reason, soft body armors have been produced by impregnating shear thickening fluids recently on high performance fabrics. In this study, it is aimed to examine the effects of shear thickening fluid and fabric structure on the inter-yarn friction properties of para-aramid fabrics with different properties. Fumed silica was dispersed in polyethylene glycol to produce shear thickening fluid. Twaron 200 and Twaron 460 para-aramid fabrics with different properties such as threads number (105x105 and 67x67), areal density (200 gr / m 2 and 460 gr / m 2 ) and linear density (930 and 3360 Dtex) were impregnated with shear thickening fluid. It was observed that both of shear thickening fluid impregnated fabrics had higher yarn pull-out force than neat fabrics due to inter-yarn friction. When shear thickening fluid impregnated fabrics are according to maximum yarn pull-out force; Twaron 200 and Twaron 460 fabrics requires approximately 3 times and 9 times more force to pull-out the yarn in comparison to the neat fabric respectively. In this study, it has been observed that the positive effects of shear thickening fluid impregnation on energy absorption of Twaron fabrics depend on structural parameters such as threads number, areal density and linear density.
In the research for this contribution, the use of layered hybrid composites as materials for ballistic armor has been tested. As part of the study, ballistic tests of glass/aramid/carbon fiber laminated comp osite plates at different reinforcing angles, in various numbers and thicknesses were carried out and the results analyzed. Eight hybrid composite laminates, of various thicknesses 200 × 200 mm in size were produced by the hand lay-up method at angles of 0°, +/−45°. Plain and twill fabrics were used to analyze the ballistic performances at various fiber reinforcing angles. Ballistic tests were carried out at the Elazig Special Operation Branch Office, using a Beretta gun loaded with 9 mm FMJ (full metal jacket) bullets. These experiments with ballistic test equipment were conducted in accordance with international standards. During the ballistic experiments, the velocity and BFS (backface signature) was measured and evaluated. Test results suggest that five samples were successful according to NIJ 0101-06 standards. It was found that twill woven (TW) fabrics made for the study manifest a higher ballistic performance than plain-woven (PW) fabrics. UD (unidirectional), +/−45° UD fabrics were found to be more effective than 0° UD fabrics. The findings are indicative for the design of lightweight ballistic armor material.
This paper presents studies on usability of multilayered hybrid composite as personal armor material. In the scope of study, 4 hybrid composite materials with different number of layers and thickness have been produced by using three different type of fabric. Then, ballistic tests have been performed and results have been investigated. The ballistic tests have been performed by using Beretta and 9 mm FMJ bullet to the international standards (NIJ 0101-06). In the ballistic tests, the speed of bullets and the depth of penetration (DOP) occurring on the test samples have been measured and the damages have been assessed. First 2 test samples with [Glass fiber 10 /Aramid fiber 10 /Carbon fiber 10 ] sequence and 30 layers have been produced, the ballistic tests have been performed and investigated. After observing the success of these two test samples, other two test samples have been produced by reducing the number of layers to 21 with [Glass fiber 7 /Aramid fiber 7 /Carbon fiber 7 ] sequence.
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