Wyniki wyszukiwania - Biblioteka Nauki

1

Assessment of the strength reduction factor in predicting the flexural strength

100%

Alacali S. , Arslan G.

Journal of Theoretical and Applied Mechanics

|

2018

|

tom Vol. 56 nr 4

1043--1053

EN

In the design of flexural strength, the strength reduction factor φ decreases from tension- -controlled sections to compression-controlled sections to increase safety with decreasing ductility. This paper presents how to determine the reduction factor for flexural strength of reinforced concrete beams according to ACI code. In the reliability-based design, the reliable prediction of the flexural strength of reinforced concrete members is assured by the use of reduction factors corresponding to different target reliability index β. In this study, for different β and coefficients of variation of the flexural strength parameters, the flexural strength reduction factor has been investigated by using experimental studies available in the literature. In the reliability analysis part of the study, the first-order second moment approach (FOSM) has been used to determine the reduction factor. It has also been assumed that the random variables are statistically independent.

2

An experimental study on the shear strength of SFRC beams without stirrups

80%

Arslan G. , Keskin R. S. O. , Ulusoy S.

Journal of Theoretical and Applied Mechanics

|

2017

|

tom Vol. 55 nr 4

1205--1217

EN

The use of steel fibers in reinforced concrete (RC) structural members aims at the improvement of mechanical properties of such members. This study focuses on shear strength characteristics of steel fiber reinforced concrete (SFRC) beams without stirrups. Test specimens consisting of three RC and ten SFRC beams without stirrups have been tested under three-point loading in order to investigate the effects of fiber content and shear span-to-effective depth ratio on the shear strength. Furthermore, an equation developed previously for predicting the ultimate shear strength of SFRC beams without stirrups is proposed to predict the diagonal cracking strength of SFRC beams without stirrups.

3

Interaction between urethane and cannabinoid CB1 receptor agonist and antagonist in penicillin - induced epileptiform activity

80%

Arslan G. , Alici S. K. , Ayyildiz M. , Agar E.

Acta Neurobiologiae Experimentalis

|

2017

|

tom 77

|

nr 2

EN

Previous experimental studies have shown that various anesthetics alter the effects of cannabinoid agonists and antagonists on the cardiac response to different stimuli. Since no data have shown an interaction between urethane and cannabinoid signaling in epilepsy, we examined the suitability of urethane with regard to testing the effects of a cannabinoid CB1 receptor agonist and an antagonist on penicillin‑induced epileptiform activity in rats. Permanent screw electrodes for electrocorticographic (ECoG) recordings, and a permanent cannula for administration of the substances to the brain ventricles were placed into the cranium of rats. Epileptiform activity was induced by injection of penicillin through the cannula in conscious animal. The CB1 receptor agonist arachidonyl‑2‑chloroethylamide (ACEA; 7.5 μg) and the CB1 receptor antagonist [N‑(piperidin‑1‑yl)‑5‑(4‑iodophenyl)‑1‑(2,4‑dichlorophenyl)‑4‑methyl‑1H‑pyrazole‑3 carboxamide] (AM‑251; 0.25 μg) were administered intracerebroventricularly 30 minutes after the penicillin application in urethane‑anesthetized and conscious animals. Urethane completely eliminated spontaneous ictal events in ECoG recordings and reduced the frequency and total amount of epileptiform activity. It did not alter either the proconvulsant effects of AM‑251 or the anticonvulsant effects of ACEA on penicillin‑induced epileptiform activity. The electrophysiological evidence suggests that there is no possible interaction between urethane and cannabinoid CB1 receptors in this experimental model of epilepsy.

4

Long-term ascorbic acid administration causes anticonvulsant activity during moderate and long-duration swimming exercise in experimental epilepsy

70%

Tutkun E. , Arslan G. , Soslu R. , Ayyildiz M. , Agar E.

Acta Neurobiologiae Experimentalis

|

2015

|

tom 75

|

nr 2

EN

The benefits of regular exercise on brain health are undeniable. Long-term exercise increases the production of reactive oxygen species in brain. Therefore, athletes often consume antioxidant supplements to remedy exercise-related damage and fatigue during exercise. The aim of this study is to evaluate the role of ascorbic acid in the effects of different intensities of swimming exercise on the brain susceptibility to experimental epilepsy in rats. Ascorbic acid was administered intraperitoneally (ip) during three different swimming exercise programme for 90 days (15 min, 30 min, 90 min/day). The anticonvulsant activity regarding the frequency of epileptiform activity appeared in the 80 min after 500 units intracortical penicillin injection in 30 min and 90 min/day exercise groups. The administration of ascorbic acid (100 mg/kg, ip) did not alter the anticonvulsant properties seen in the in short-duration (15 min/day) swimming exercise group. The amplitude of epileptiform activity also became significant in the 110 and 120 min after penicillin injection in the moderate (30 min/day) and long duration (60 min/day) groups, respectively. The results of the present study provide electrophysiologic evidence that long-term administration of ascorbic acid causes anticonvulsant activities in the moderate and long-duration swimming exercise. Antioxidant supplementation such as ascorbic acid might be suggested for moderate and long-duration swimming exercise in epilepsy.