Evaporation heat transfer and pressure drop characteristics of R-600a in horizontal smooth and helically dimpled tubes

An experimental investigation was performed to evaluate the heat transfer and pressure drop characteristics of the hydrocarbon refrigerant R-600a during flow boiling inside a horizontal smooth tube with an inside diameter of 8.25 mm and a newly developed dimpled tube. The inner surface of the helically dimpled tube is enhanced by a newly modified pattern consists of both shallow and deep protrusions. The experimental tests were carried out varying: the refrigerant mass fluxes within the range of 155–470 kg/m2 s; the vapor qualities up to 0.8; the constant heat flux of 15.8 and saturation temperature of 56.5 °C. Observations clearly indicate that the heat transfer performance is improved as tube’s inner surface enhanced by this new pattern of protrusions. The experimental results show that the heat transfer coefficients of the dimpled tube are 1.29–2 times larger than a smooth tube with a pressure drop just ranging between 7% and 103% larger than the smooth tube. The highest enhancement in the heat transfer coefficient occurs at vapor quality of 0.2 and mass flow rate of 155 kg/m2 s. On the other hand, the maximum increase of pressure drop takes place at vapor quality of 0.8 and mass flow rate of 305 kg/m2 s

Condensation heat transfer and pressure drop characteristics of R-600a in horizontal smooth and helically dimpled tubes

In the present study, condensation heat transfer and frictional pressure drops of refrigerant R-600a (iso-butane) inside a helically dimpled tube and a plain tube of internal diameter 8.3 mm were measured and analyzed. All tests were performed at different vapor qualities up to 0.82 and average saturation temperatures ranging between 38 and 42 °C. Refrigerant mass fluxes varied in the range of 114–368 kg/m2 s. The inner surface of the helically dimpled tube has been designed and reshaped through three-dimensional material surface modifications consists of both shallow and deep protrusions which are placed evenly in helical directions on the tube wall. The experimental results show that the heat transfer coefficients of the dimpled tube are 1.2–2 times of those in smooth tube with a pressure drop penalty just ranging between 58% and 195. The highest heat transfer coefficient is occurred at vapor quality of 0.53 and mass flow rate of 368 kg/m2 s. On the other hand, the maximum increase of pressure drop takes place at vapor quality of 0.55 and mass flow rate of 368 kg/m2 s

Visual study of flow patterns during evaporation and condensation of R-600a inside horizontal smooth and helically dimpled tubes

In this paper, flow patterns and their transitions for the refrigerant R-600a during flow boiling and condensation inside a helically dimpled tube and a smooth tube were observed and analysed. The inner surface of the helically dimpled tube was enhanced by a modified pattern consisting of both shallow and deep protrusions. For evaporation, the experiments were performed for refrigerant mass velocities in a range of 155 kg/m2 s to 467 kg/m2 s, all at an average saturation temperature of 56.5 °C with the vapour qualities up to 0.8. Stratified-wavy, intermittent, and annular flows were observed for the smooth tube; for the dimpled tube, the stratified-wavy flow was not seen. For condensation, all tests were conducted at vapour qualities up to 0.8, and average saturation temperatures ranging between 38 °C and 42 °C. The refrigerant mass fluxes varied in the range of 114–368 kg/m2 s. Annular, intermittent, and stratified-wavy flows were recognized for the plain tube, but there was no stratified-wavy flow in the flow pattern visualization of the dimpled tube. The investigation clearly shows that the dimples in both evaporation and condensation have a significant impact on the two-phase flow pattern. Inside the helically dimpled tube, the transition from intermittent to annular (or vice versa) occurred at a lower vapour quality value than for the smooth tube

An investigation on artificial reproduction of Mugil cephalus

Cultured nine years old breeder M. cephalus specimens were subjected to eight artificial breeding treatments from December till February 2003. In treatments 1-5, breeders received two injections of CPH and LIIRFI—A2 coupled with Domperidone or a mixture of CPH and HCG in an interval of 24 hours. Female breeders in treatments 6-8 received a gradual daily injection of 500 1U HCG per kilogram of body weight for 5 days. Male breeders in treatments 6-8 were given 5-10mg of MT-a-17 in addition to HCG and then subjected to two injections similar to that of treatments 1-5. Results showed that male breeders in stages +2 and +3 of all treatments that had received HCG produced more milt than those injected with MT-a-17, such that each male was used 2-6 times for milting purposes. Of 27 female breeders, 22 spawned 1-2.6 million eggs among which eight females' eggs were fertilized 10-95%. Hatching rate was between 0.008 to 88.9% and a maximum of 2 million larvae were produced. The best time for artificial breeding is December when mean egg width is ,600 microns. Statistical analysis of egg width, hatching rate and larvae production showed a significant difference between treatments 1-5 and 6-8 (p<0.05). This proved the supremacy of multiple injections including HCG for artificial breeding of Mugil cephalus

Titration of the Iranian white spot virus isolate, on crayfish Astacus leptodactylus and Penaeus semisulcatus

White Spot Virus (WSV) is currently the most serious viral pathogen of shrimp worldwide; it causes mortality up to 100% within 7-10 days in commercial shrimp farms. Infected Indian white shrimp Fenneropenaeus indicus samples were collected from Guatr shrimp site in Sistan and Baluchestan province in south of Iran and WSV infection was confirmed by Nested PCR. WSV was isolated from infected shrimp samples by centrifugation and filtration and multiplied in crayfish by intramuscular inoculation, the isolated virus was called WSV/IRN/1/2010. In order to determine the dilution resulting in 90-100% mortality in Penaeus semiculcatus, diluted virus stock in steps from 10^0 till 10^5 times in sterile PBS was injected intramuscularly to 14 shrimps in each group. Also the virus stock was diluted in steps from 1/2 till 1/32 times in sterile PBS and injected intramuscularly in Astacus leptodactylus crayfish. Therefore the LD50 of live virus stock in Astacus leptodactylus and Penaeus semiculcatus crayfish were calculated by the Karber method 10^3.29 /ml and 10^5.35 /ml, respectively

Health promotion, disease prevention and periodic health checks: perceptions and practice among family physicians in eastern Mediterranean region

Introduction: The aim of this study was to identify the current practices and perceptions of family physicians regarding health promotion, disease prevention including periodic screening and health checks in Eastern Mediterranean Region. Methods: A multi-country cross-sectional study was conducted in six countries of EMR, from September 2014 to March 2015. Family Physicians who were currently practicing in different countries of EMR were invited to participate in the study through email. A pre-tested structured questionnaire was used for data collection. Data was entered and analyzed on SPSS 19 and logistic regression analysis was performed. Results: A total of 100 physicians data was included in the final analysis. The majority were female physicians (76%): 63% were 25 to 35 years of age. Approximately 53% of Family physicians always recommend periodic screening and health checks to their patients. The common screening question asked to patients in medical history was related to their blood pressure (86%). Almost all (99%) of the Family physicians believe they should conduct periodic health checks. Those who had postgraduate training in Family Medicine (OR: 0.5; 95% CI: 0.39-1.67) and attended CME sessions regularly (OR: 0.11; 95% CI: 0.01-0.93), are more likely to recommend periodic screening and health checks to their patients. Conclusion: Periodic screening and health check is an important strategy to prevent disease and maintain health. It is an underutilized practice and a great need exists for its implementation in family practice

New leadership model for family physicians in the Eastern Mediterranean region: a pilot study across selected countries

Background: Family Medicine is growing rapidly across the Eastern Mediterranean Region. However, it needs support in terms of overall health system development. This will require strong leadership in family medicine to implement the change required to improve current conditions. Objective: To collect data that will support the development of a leadership program for the future family physicians in the region. Methods: A cross-sectional study was conducted from July 2016 to September 2016 in eight countries of the Eastern Mediterranean Region, (Bahrain, Egypt, Iraq, Jordan, Kuwait, Qatar, Pakistan, and Saudi Arabia). These countries were selected to obtain perceptions of Family Physicians (FPs) regarding the current leadership model and to explore the need for a new future innovative model in Family Medicine (FM) across the region. Results: The information of 68 family physicians was included in the final analysis. The majority of the FPs was females as compared to males (71% vs. 29%). Forty-four percent of the FPs had 10 to 19 years of experience. Almost all of the FPs (96%) had completed some training in family medicine after graduation. About three fifths of the FPs had completed postgraduate qualifications and out of those, 64% had passed Board or Membership Examinations. Twenty-one percent of them are currently in a leadership role and 45% who were not in any leadership role responded that the current situation of FM in their country is poor. All of the leaders believed that it is important to develop strong leadership in FM to take the specialty forward. Almost similar proportions (67% and 64%) of leaders and non-leaders thought that establishing regional associations would enhance the FM practice model. Approximately two thirds of leaders (67%) responded that the current role of decision makers in the Ministry of Health (MOH) regarding capacity building in FM is not effective. The majority of the FPs (54% and 38%) considers that the existing postgraduate curriculum does not address leadership skill development in FM. Eighty-eight percent of the FPs both from leadership and non-leadership groups agreed that academic institutions and practicing FPs can play an effective leadership role in taking FM forward. Conclusion: The Family Medicine specialty will have to develop leadership capabilities in line with today’s fast-moving changes in healthcare for it to obtain the due recognition in the healthcare delivery system

Health promotion, disease prevention and periodic health checks: perceptions and practice among family physicians in Eastern Mediterranean region

Introduction: The aim of this study was to identify the current practices and perceptions of family physicians regarding health promotion, disease prevention including periodic screening and health checks in Eastern Mediterranean Region. Methods: A multi-country cross-sectional study was conducted in six countries of EMR, from September 2014 to March 2015. Family Physicians who were currently practicing in different countries of EMR were invited to participate in the study through email. A pre-tested structured questionnaire was used for data collection. Data was entered and analyzed on SPSS 19 and logistic regression analysis was performed. Results: A total of 100 physicians’ data was included in the final analysis. The majority were female physicians (76%): 63% were 25 to 35 years of age. Approximately 53% of Family physicians always recommend periodic screening and health checks to their patients. The common screening question asked to patients in medical history was related to their blood pressure (86%). Almost all (99%) of the Family physicians believe they should conduct periodic health checks. Those who had postgraduate training in Family Medicine (OR: 0.5; 95% CI: 0.39-1.67) and attended CME sessions regularly (OR: 0.11; 95% CI: 0.01-0.93), are more likely to recommend periodic screening and health checks to their patients. Conclusion: Periodic screening and health check is an important strategy to prevent disease and maintain health. It is an underutilized practice and a great need exists for its implementation in family practice

Barriers, challenges and way forward for implementation of person centered care model of patient and physician consultation: a survey of patients’ perspective from Eastern Mediterranean countries

Background: Person-Centered Care (PCC) is now considered a mandatory approach in Patient-Physician consultation. The aim of the study was to identify patients’ perception regarding barriers and possible remedies for implementation of PCC in Eastern Mediterranean Region (EMR). Methods: A cross-sectional multi-country study was conducted in six countries of EMR during May 2014 to October 2014. Expert Family Physicians from each country were identified and asked to participate in the study. The Family Physicians then recruited Patients from their own clinics (\u3e18 years). Data analysis was performed on SPSS 19 and results are reported in the form of proportions, odds ratios and 95% confidence intervals. Results: A total of 234 patients were recruited, 60.6% were aged between 20 to 30 years and 36.3% of them were males. 56% of the patients preferred Person-Centered Care model for patient-physician consultation. The major barriers identified by patients in its implementing were; time constraints (73.9%, OR: 1.5; 95% CI: 0.86-2.78), doctors desire to control patient (OR: 2.6; 95% CI: 1.55-4.49), cultural and religious reasons (52.1%), increased cost (50.9%). Patients responded that increased cost related to Person-Centered Care practice would be acceptable (58.1%), if increase proved to be in the interest of better health and care outcomes (40.6%). Conclusion: Person-Centered Care (PCC) is associated with significant barriers in its implementation in Eastern Mediterranean Region. These barriers can be overcome in the interest of better health and care related outcomes

Study on health and Immunity index of vaccinated Litopenaeus vannamei against white spot virus disease

In this study, the inhibitory effect of Radio-Vaccine against white spot disease on white shrimp (Litopenaeus vannamei) was studied. This vaccine was prepared by Nuclear Science and Technology Research Institute of Atomic Energy Organization of Iran. 14,000 L. vannamei postlarvae were used in treatments after adaptation. Eight treatments, four positive and two negative controls were considered in triplicate. Initially, three meals a day for a month in the hours of 8, 16 and 24 were feeding. Three times in day at 8, 16 and 24 clock were feeding in first mount. Waste food and fecal remaining in the tanks were removed. In the second and third months of treatment, feeding frequency increased to three and four times in day which is at 6, 18 and 24 were given concentrate feed and Artemia nauplii at 12 clocks. Vaccination was carried out by immersion. Vaccination was performed in two doses with an interval of 10 to 14 days. For biometric testing and evaluation of immune cells throughout the experiment, three samples were taken randomly from the tanks. To assess the health status of shrimp, indices of Total Hemocyte Count and Total Plasma Protein was determined. Phagocytic activity of hemocytes was evaluated to assess immune setuation of shrimps. The results of this study showed that the shrimp immune system, as in many reports, the effect of recombinant vaccines and passive safety in memory as "Alternative adaptive immune responses" after experimental infection of white spot virus (WSSV) in wild and farmed shrimp is confirmed, will respond to vaccination against white spot disease