Increasing the Production of Carotenoids in Chlorella sorokiniana IG-W-96 by Changing the Concentration of Nutrients and Phytohormones

Introduction  Carotenoids have many effects on human health. These compounds are produced by plants and microalgae. The extraction of carotenoids from microalgae such as Chlorella has received much attention, since microalgae grow all year round (regardless of the season) and at a much faster rate than plants in non-arable lands. The aim of this research was to optimize the concentrations of nutrients (nitrogen and phosphorous) in the growth medium of microalgae with the objective of maximizing carotenoids content. At the optimized nutrient conditions, the effect of phytohormones on production of carotenoids using Chlorella sorokiniana IG-W-96 was investigated.   Materials and Methods Chlorella sorokiniana IG-W-96 was cultivated in BG11 growth medium with light intensity of 25000 lux and light: dark cycle of 16: 8 supplied with compressed air flow of 0.5 vvm containing 6% vol carbon dioxide. Under three concentrations of nitrate (0.04, 0.25, 1.5 ) and three concentrations of phophate (0.01, 0.04, 0.16 ) and carotenoid concentration was measured. Full factorial experimnetal design was performed and the resuts of the experiments were analyzed using Minitab (ver. 21.01.1). Finally, the best concentrations of nitrate and phosphate were chosen for pigments production, and at that concentration, naphthalene acetic acid (0, 2.5, 5, 7.5, 10 and 12 ppm) was added to the culture medium to check its effect on pigments production. By measuring the dry weight of C. sorokiniana, its growth rate was determined. After extracting the pigments with solvent, the concentration of the pigments was determined by measuring the amount of light absorption.   Results and Discussion Dry weight The results showed that the highest amount of dry weight was related to the treatment with nitrate amount of 0.25 , and nitrate more and less than this amount caused a decrease in growth. This result was not dependent on the amount of phosphate and was true for all phosphate concentrations. Nitrate reduction from 1.5 to 0.25 increased the growth of microalgae up to 81.8%, so that the dry weight of 0.88  reached 1.6 . However,  reduction of nitrate from 0.25 to 0.04  decreased the dry weight by 65.6%. In order to reach the maximum growth rate, it is necessary to determine the appropriate concentration of each nutrient.   Carotenoids Unlike the dry weight, not only the pigment production did not decrease with the excessive of nitrate concentration, but also the maximum amount of pigment production was related to the treatment with the maximum amount of nitrate concentration. Based on the results obtained, the concentration of carotenoids was higher in the concentration of 1.5  of nitrate and 0.04  of phosphate (6.7 ). When the nitrate concentration was very low (0.04 ), changing the phosphate concentration had no significant effect on the production rate of any of the pigments. Only when the nitrate concentration was high (1.5 ), change in phosphate concentration caused a change in pigments concentration. The increase of phosphate concentration from 0.01 to 0.04 increased the carotenoids concentration to 1.65-fold. Of course, increasing phosphate concentration to 0.16 did not affect the pigments concentration.  Based on the statistical analysis, the P-value<0.05 indicated that the effect of the factors and the model was significant. In this situation, in order to increase the production of carotenoids, naphthalene acetic acid was added to the phytohormone culture medium. At the optimal concentration of 2.5 ppm of naphthalene acetic acid, the concentration of carotenoids increased by 26.71% and reached 8.49 . However, phytohormone had no significant effect on dry weight.   Conclusion Carotenoid production using microalgae could be maximized through optimization of nutrients concentrations (nitrate and phosphate) in the growth medium. Phytohormones could further increase the prodcution of carotenoids at optimum concnetrations

What is the potential of tissue-engineered pulmonary valves in children?

BACKGROUND: As a living heart valve substitute with growth potential and improved durability, tissue-engineered heart valves (TEHV) may prevent re-interventions that are currently often needed in children with congenital heart disease. We performed early Health Technology Assessment to assess the potential cost-effectiveness of TEHV in children requiring right ventricular outflow tract reconstruction (RVOTR). METHODS: A systematic review and meta-analysis was conducted of studies reporting clinical outcome after RVOTR with existing heart valve substitutes in children published between 1/1/2000-2/5/2018. Using a patient-level simulation model, costs and effects of RVOTR with TEHV compared to existing heart valve substitutes were assessed from a healthcare perspective applying a 10-year time horizon. Improvements in performance of TEHV, divided in durability, thrombogenicity, and infection resistance, were explored to estimate quality-adjusted life years (QALY) gain, cost reduction, headroom, and budget impact associated with TEHV. RESULTS: Five-year freedom from re-intervention after RVOTR with existing heart valve substitutes was 46.1% in patients ≤2 years old and 81.1% in patients >2 years old. Improvements in durability had the highest impact on QALYs and costs. In the ‘improved TEHV performance’ scenario (durability≥5 years and -50% other valve-related events), QALY gain was 0.074 and cost reduction was €10,378 per patient, translating to maximum additional costs of €11,856 per TEHV compared to existing heart valve substitutes. CONCLUSIONS: This study showed that there is room for improvement in clinical outcomes in children requiring RVOTR. If TEHV result in improved clinical outcomes, they are expected to be costeffective compared to existing heart valve substitutes

Three options for citation tracking: Google Scholar, Scopus and Web of Science

BACKGROUND: Researchers turn to citation tracking to find the most influential articles for a particular topic and to see how often their own published papers are cited. For years researchers looking for this type of information had only one resource to consult: the Web of Science from Thomson Scientific. In 2004 two competitors emerged – Scopus from Elsevier and Google Scholar from Google. The research reported here uses citation analysis in an observational study examining these three databases; comparing citation counts for articles from two disciplines (oncology and condensed matter physics) and two years (1993 and 2003) to test the hypothesis that the different scholarly publication coverage provided by the three search tools will lead to different citation counts from each. METHODS: Eleven journal titles with varying impact factors were selected from each discipline (oncology and condensed matter physics) using the Journal Citation Reports (JCR). All articles published in the selected titles were retrieved for the years 1993 and 2003, and a stratified random sample of articles was chosen, resulting in four sets of articles. During the week of November 7–12, 2005, the citation counts for each research article were extracted from the three sources. The actual citing references for a subset of the articles published in 2003 were also gathered from each of the three sources. RESULTS: For oncology 1993 Web of Science returned the highest average number of citations, 45.3. Scopus returned the highest average number of citations (8.9) for oncology 2003. Web of Science returned the highest number of citations for condensed matter physics 1993 and 2003 (22.5 and 3.9 respectively). The data showed a significant difference in the mean citation rates between all pairs of resources except between Google Scholar and Scopus for condensed matter physics 2003. For articles published in 2003 Google Scholar returned the largest amount of unique citing material for oncology and Web of Science returned the most for condensed matter physics. CONCLUSION: This study did not identify any one of these three resources as the answer to all citation tracking needs. Scopus showed strength in providing citing literature for current (2003) oncology articles, while Web of Science produced more citing material for 2003 and 1993 condensed matter physics, and 1993 oncology articles. All three tools returned some unique material. Our data indicate that the question of which tool provides the most complete set of citing literature may depend on the subject and publication year of a given article

Webometrics benefitting from web mining? An investigation of methods and applications of two research fields

Webometrics and web mining are two fields where research is focused on quantitative analyses of the web. This literature review outlines definitions of the fields, and then focuses on their methods and applications. It also discusses the potential of closer contact and collaboration between them. A key difference between the fields is that webometrics has focused on exploratory studies, whereas web mining has been dominated by studies focusing on development of methods and algorithms. Differences in type of data can also be seen, with webometrics more focused on analyses of the structure of the web and web mining more focused on web content and usage, even though both fields have been embracing the possibilities of user generated content. It is concluded that research problems where big data is needed can benefit from collaboration between webometricians, with their tradition of exploratory studies, and web miners, with their tradition of developing methods and algorithms

Exploring the relationships between the burnout and psychological wellbeing, among teachers while controlling for resiliency and gender

Background and aims   The present study aimed at exploring the relationships between the subscales of burnout and psychological wellbeing .in this study resiliency and gender were  controlled among two groups were compared on the subscales of burnout and wellbeing.   Methods   For sampling, 127 teachers of elementary schools in Tehran were selected using multistage cluster sampling who answered Maslach and Jakson burnout inventory (MBI), GHQ and CD-RISC.   Results   Findings indicates male teachers had a better status in anxiety, physical symptoms and depression subscales of general health questioner (GHQ). The comparison of male and female  teacher in the subscales of burnout showed there was a significant difference between the two   groups only in the subscales of emotional exhaustion, and woman had a weaker performance in comparison to men. Findings also indicated there was appositive and significant relationship between the component of burnout and mental health problems (including anxiety, physical   symptoms and depression and social function) after controlling for resiliency and gender.   Conclusion   The result of regression analyzes showed that mental health of teacher in general could predict their burnout