An in-vitro study on the accuracy of conventional film optical densitometry and densitometry in radiovisiography system

Nowadays, bone mass estimation, through imaging methods, is widely used in metabolic"ndiseases diagnosis and treatment. One of these methods is called "optical densitometry" which estimates bone density by measuring the intensity of the transmitted light on different parts of a radiographic image. Digital radiography systems act similarly by determining grey levels of the image. The aim of this study is comparing two different methods of optical densitometry and a digital system densitometry known as radiovisiography. 45 samples, containing urografin with three different concentrations, were imaged, by both radiovisiogrphy (RVG) and conventional film systems. To determine the densitometry of films and radiovisiography images, optical densitometry and bone densitometry option of the RVG software, were applied respectively. Data were analyzed and compared for their reliability (repeatability) and correlations with concentration. In RVG densitometry system, the correlation with concentration is moderate (r=0.42) and intra samples and intra group reliability are 97.68% and 88.19%. Moreover, in conventional optical film densitometry, correlation with concentration (r=0.987) is high, intra samples and intra group reliability is high, intra samples and intra group reliability are 99.97% and 99.84%, respectively. According to the results, it is suggested that conventional film optical densitometry is more precise and reliable than RVG densitometry

Residual compressive stress–strain relationship of lightweight aggregate concrete after exposure to elevated temperatures

This experimental study investigated the compressive behavior of lightweight concrete after exposure to elevated temperatures. In total, 240 samples from 30 different mixtures were prepared and tested to evaluate the compressive strength, elastic modulus, strain at peak stress, and stress–strain relationships of lightweight aggregate concrete (LWAC) after being exposed to elevated temperature of 250, 500, and 750 °C. Test variables were composed of cement content varied between 300 and 700 kg/m3, volumetric percentage of lightweight expanded clay aggregates (Leca) substituting natural sand and gravel at 0, 25, 50, 75, and 100% (by weight), silica fume replacing cement at 5, 7.5, 10, 12.5, and 15% (by weight) and different water to cement ratios of 0.250, 0.313, 0.375, 0.438, and 0.500. The compressive strength, elastic modulus, and strain in the maximum stress were compared with predictions from the American and European standards and the proposed analytical models. The results showed that the compressive strength and elastic modulus of LWAC declined with increasing the temperature. The samples S6, S4 and S23 performed better compared to other specimens at elevated temperature as they retained about 96%, 75% and 42% of compressive strength, respectively after exposure to 250, 500 and 750 °C. A higher residual compressive strength was observed in the sample including 75% Leca at 750 °C. The experimental stress–strain relationship was verified according to the available analytical models and an analytical model was proposed to estimate the compressive behavior of LWAC at elevated temperature

Effect of N-acetylcysteine with letrozole to induction of ovulation in infertile women with polycystic ovarian syndrome

Background and Objective: Polycystic ovary syndrome (PCOS) is the most endocrine disorder in women. This study was done to determine the effect of N-acetylcysteine with letrozole to induction of ovulation in infertile women with polycystic ovarian syndrome. Methods: This clinical trail study was carried out on forty PCOS women with normal TSH, prolactin, hysterosalpingographies and normal spermograms. The patients in control group were received letrozole 5 mg/d for 5 days starting at day 3 of the cycle. The patients in interventional group were received letrozole 5 mg/d with NAC 1.2 g/d (group II) for 5 days starting at day 3 of the cycle. On 14th day of cycle, transvaginal ultrasonography was performed to evaluate endometrial thickness and follicles properties. If mature follicle detected, hCG was injected and timed coitus at 12, 36 and 60 hours later advised. β-hCG level was checked on day 16 after hCG injection. Results: The mean of endometrial thickness and follicles ovulation in hCG injection day was similar in the two groups. The pregnancy rate was 15% and 20% in control and interventional groups, respectively. This difference was not significant. The mean of follicles number was 1.13% and 1.47% in control and interventional groups, respectively. This difference was not significant. Conclusion: NAC as an adjuvant to letrozole was not effective for ovulation induction in patients with PCOS