Annual performance evaluation of a hybrid concentrated solar-micro gas turbine based on off-design simulation.

As the adoption of solar hybrid systems continues to rise due to their potential to compensate for the fluctuation of solar irradiation, it becomes imperative to accurately evaluate their performance, considering the variation of off-design conditions. This paper introduces a detailed analysis method for evaluating the annual performance of a solar-MGT system under transient boundary conditions for a whole-year operation range. A hybrid system of a micro gas turbine, recuperator, and solar dish is considered, and an off-design simulation model is developed and verified with available experimental results. Two different configurations for a recuperated cycle are considered, and simulations are conducted for a test case in Pretoria, SA. The results for Jun.21 and Dec.21 as low and high solar energy days are reported with more details to compare the configurations and demonstrate the effect of ambient temperature on the heat loss of the solar receiver and the overall performance of the system. The alternative configuration reduces heat loss with a lower temperature receiver but has higher fuel consumption compared to the conventional configuration. Operating strategies for different hours of operation from 1 h to 24 h per day are simulated for 365 days, based on real meteorological data, and compared with the operating in solar available hours. It is shown that the whole-year simulation of the system considering the variation of boundary conditions can change the estimation of fuel consumption by 25 %.

Assessing the interstitial cells of Cajal, cells of enteric nervous system and neurotransmitters in slow transit constipation, using immunohistochemistry for CD117, PGP9.5 and serotonin.

BACKGROUND/AIMS: Slow transit constipation is one of the common causes of chronic constipation, in which the intestinal diameter is normal, but its transit time is markedly increased. The underlying cause in this disease is not definitely understood. METHODOLOGY: In this study was investigated the difference in the quantity of pace maker cells, cells of enteric nervous system and serotonin positive cells in normal colon and colon of the patients with slow transit constipation by using immunohistochemistry for c-Kit, PGP 9.5 and serotonin. RESULTS: The number of c-Kit positive pacemaker cells in the muscular layer was significantly decreased in the patients with slow transit constipation. PGP 9.5 positive enteric nervous system cells were significantly decreased in the patients with slow transit constipation in inner circular layer. Number of serotonin positive cells in the patients with slow transit constipation was significantly increased. CONCLUSIONS: Slow transit constipation is most probably a true enteric neuropathy.

Assessment of electrotherapy in treatment of hemorrhoids in Southern Iran.

OBJECTIVE: In this study, we have developed an electrotherapy device in order to improve the outcome and decrease the number of referrals and duration of treatment of internal hemorrhoid. METHODS: We treated 2015 hemorrhoids among 931 patients (382 males and 549 females); 319 hemorrhoids were grade 1, 1158 grade 2 and 538 grade 3, from May 1995 to October 2002, at Nemazee and Faghihee Hospitals in Shiraz University of Medical Sciences, Shiraz, Iran. All patients were referred due to fresh rectal bleeding or reducible prolapsed hemorrhoid with no response to medical treatment. After introduction of anesthesia, 27-30 mAmp direct current was applied to each hemorrhoid with durations of 4.5 minutes for grade 1, 5.5 minutes for grade 2 and 7 minutes for grade 3. RESULTS: Our results showed that 97.1% of patients responded well to the treatment and 27 patients returned with fresh rectal bleeding or prolapsed hemorrhoid in 2 weeks to 2 months postoperatively. Ninety-six percent of the patients were discharged on the same operating day. After 24 hours postoperation, 92% of the patients had no any pain and no need any analgesic. Among those patients who had not responded to the treatment; 24 cases underwent electrotherapy for a 2nd time and 3 patients were treated excising their prolapsed hemorrhoids. No other complications were detected. CONCLUSION: Postoperative pain was mild and tolerable and 93.2% of patients returned to normal activity after 2 days. Electrotherapy with the above mentioned method is considered safe and effective without any major complications and with acceptable patient's satisfaction. This method can be used for treatment of grades 1, 2 and 3 hemorrhoids.