6,486 research outputs found
Peroxynitrite and nitryl chloride enhance astaxanthin production by the green microalga Chlorella zofingiensis in heterotrophic culture
No full textThe fast growing unicellular green microalga Chlorella zofingiensis has attracted interest as a promising organism for commercial production of the high-value carotenoid astaxanthin [Del Campo JA, Rodriguez H, Moreno J, Vargas MA, Rivas J, Guerrero MG. Accumulation of astaxanthin and lutein in Chlorella zofingiensis. Appl Microbiol Biotechnol 2004;64:848-54; Ip PF, Wong KH, Chen F. Enhanced production of astaxanthin by the green microalga Chlorella zofingiensis in mixotrophic culture. Process Biochem 2004;39:1761-6; Ip PF, Chen, F. Production of astaxanthin by the green microalga Chlorella zofingiensis in the dark. Process Biochem 2005;40:733-8.]. In this study, the reactive nitrogen species (RNS) peroxynitrite and the reactive nitrogen intermediate (RNI) nitryl chloride were applied to induce carotenogenesis leading to enhanced astaxanthin formation in C. zofingiensis in dark heterotrophic culture. Both the RNS and RNI when applied at an appropriate concentration stimulated astaxanthin biosynthesis in C. zofingiensis. Cultures treated with 1 mM peroxynitrite led to an enhanced yield of astaxanthin from 9.9 to 11.78 mg l-1. Nitryl chloride generated from the reaction mixture of 0.1 mM sodium nitrite with 0.5 mM sodium hypochlorite also increased the astaxanthin yield to 10.99 mg l -1. The present study is the first report demonstrating the possibility of using RNS and RNI for the enhancement of astaxanthin production in heterotrophic microalgal culture. © 2005 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex
Employment of reactive oxygen species to enhance astaxanthin formation in Chlorella zofingiensis in heterotrophic culture
No full textThe advantages of using heterotrophic cultivation for commercial production of the high-value ketocarotenoid astaxanthin by microalgae have been emphasized in recent years [Chen F. High cell density culture of microalgae in heterotrophic growth. Trends Biotechnol 1996;14:421-5; Chen F, Chen H, Gong X. Mixotrophic and heterotrophic growth of Haematococcus lacustris and rheological behaviour of the cell suspensions. Bioresour Technol 1997;62:19-24; Ip PF, Chen F. Production of astaxanthin by the green microalga Chlorella zofingiensis in the dark. Process Biochem 2005;40:733-8]. In a heterotrophic culture where light is not provided, the employment of oxidative stress is essential for promoting the formation of secondary carotenoids including astaxanthin. In the present study, oxidative treatment imposed by chemically generated reactive oxygen species (ROS) including the hydroxyl radicals (OH) and singlet oxygen ( 1O2) for inducing carotenogenesis and astaxanthin production by C. zofingiensis in heterotrophic culture was investigated. OH stimulated secondary carotenoids accumulation significantly, whereas 1O2 did not. The addition of 0.1 mM hydrogen peroxide to the culture leading to the generation of OH enhanced the yield of astaxanthin from 9.9 mg l-1 to 12.58 mg l-1. These results indicate that the application of a suitable type and dosage of ROS is potentially useful for mass production of astaxanthin by C. zofingiensis in heterotrophic culture. © 2005 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex
Nonlinear adjustments in deviations from the law of one price for wholesale hog prices
No full text[[abstract]]This article applies the Band-Threshold Autoregression (Band-TAR) model to investigate whether the law of one price (LOOP) holds in Taiwanese wholesale hog markets during the period from May 1987 through December 2003. We find evidence of a nonlinear mean reversion in deviations from the LOOP for relative hog prices. Our empirical study confirms the presence of thresholds and provides strong evidence in support of the view that the regional hog markets have been tightly integrated in Taiwan and that the wholesale hog market in Taiwan is an efficient market economy. Furthermore, the estimated half-lives from the nonlinear generalized impulse response analysis are as short as four months.[[note]]SC
Asymmetric effects of investor sentiment on industry stock returns: Panel data evidence
No full text[[abstract]]This article employs a state-of-the-art panel threshold model by allowing for regime intercepts, in order to shed new light on the asymmetric/nonlinear effects of local and global sentiments on expected industry stock returns among 11 Asian countries during the period from 1996 to 2010. Empirical evidence demonstrates that once the regime intercept is included, the asymmetric effects of global sentiment on oil & gas, financials, and health care industry returns become less under optimism, as compared with under pessimism. More critically, the positive (negative) impact of global sentiment above (under) the threshold turns significant, indicating that global optimism leads industry returns to be overvalued, while pessimism leads them to be undervalued. For local market sentiment, our results support that higher local sentiment enhances the returns of basic materials, telecommunications, and utilities industries. The empirical results confirm that the nexus of industry returns and investor sentiments is subject to change between different sentimental intervals. (C) 2012 Elsevier B.V. All rights reserved.[[note]]SSC
Village distribution and geographic variations of the prevalence of chronic hepatitis B, C and hypertransaminemia: an analysis of adult health examinations in 520 village of Tainan county, Taiwan
No full textFurther evidence on property-casualty insurance premiums: Do multiple breaks and country characteristics matter?
No full text[[abstract]]This paper employs a panel data stationarity test that incorporates multiple structural breaks to investigate whether property-casualty insurance (PCI) premiums per capita among 40 countries are mean-reverting or not. The results suggest that our panel dataset is stationary after we introduce the structural breaks into the model and consider cross-sectional dependence. However, the results for the panel stationarity test vary with regard to different country characteristics. Countries in which the PCI premiums present a panel unit-root property infer that any external shocks can have a permanent effect on the insurance premiums. Accordingly, the associated insurance authorities should take possible structural breaks and cross-sectional dependence into account when implementing related policies. (C) 2012 Elsevier BM. All rights reserved.[[note]]SSC
Altered muscle activation characteristics associated with single volitional forward stepping in middle-aged adults
No full textDo CO2 emission levels converge among 21 OECD countries? New evidence from unit root structural break tests
No full text[[abstract]]This study empirically re-investigated whether carbon dioxide (CO(2)) emissions series were stationary in 21 OECD countries during the 1960-2000 period. A suite of test statistics were employed, proposed by Sen (2003), with a model that simultaneously allows for a break within the context of Perron's (1989) mixed intercept and slope (Model C). The distinction between this study and previous ones lies in its control for breaks. Compared with the results from traditional unit root tests, the empirical findings provide further evidence that relative per capita CO(2) emissions were stationary and were stochastically converging. In addition, structural breaks are identified in each country, and some important policy implications emerge from the results.[[note]]SSC
The nexus between defense expenditure and economic growth: New global evidence
No full text[[abstract]]This paper applies a two-step Generalized Method of Moments (GMM) to re-examine the causality between defense burden (MB) and real GDP (RY) for 137 countries. The findings indicate that a short-run causality running from MB to RY is found in lower-middle- and high-income countries and that from RY to MB is found in low-income countries, while bidirectional short-run causality is found in Asia, Europe, Latin America & the Caribbean and the Middle East & North Africa. No causality is found in upper-middle-income, European & Central Asian and Sub-Saharan African countries. Thus, our results do not support that one size fits all. This paper contributes important implications to the countries for making their defense policy. (C) 2013 Elsevier B.V. All rights reserved.[[note]]SSC
- …
