Qualitative and quantitative analysis of solar hydrogen generation literature from 2001 to 2014

Solar hydrogen generation is one of the new topics in the field of renewable energy. Recently, the rate of investigation about hydrogen generation is growing dramatically in many countries. Many studies have been done about hydrogen generation from natural resources such as wind, solar, coal etc. In this work we evaluated global scientific production of solar hydrogen generation papers from 2001 to 2014 in any journal of all the subject categories of the Science Citation Index compiled by Institute for Scientific Information (ISI), Philadelphia, USA. Solar hydrogen generation was used as keywords to search the parts of titles, abstracts, or keywords. The published output analysis showed that hydrogen generation from the sun research steadily increased over the past 14 years and the annual paper production in 2013 was about three times 2010-paper production. The number of papers considered in this research is 141 which have been published from 2001 to this date. There are clear distinctions among author keywords used in publications from the five most high-publishing countries such as USA, China, Australia, Germany and India in solar hydrogen studies. In order to evaluate this work quantitative and qualitative analysis methods were used to the development of global scientific production in a specific research field. The analytical results eventually provide several key findings and consider the overview hydrogen production according to the solar hydrogen generation

In vitro propagation of Brazilian ginseng [Pfaffia glomerata (Spreng.) Pedersen] as affected by carbon sources

This study aimed to establish a protocol for in vitro propagation of two accessions (Ac) of Pfaffia glomerata (Ac 4 and Ac 13) and to evaluate the effect of different carbon sources on the production of 20-hydroxyecdysone (20E) in leaves and roots. For the assessment of axillary shoot proliferation in vitro, nodal segments were inoculated onto Murashige and Skoog (MS) medium supplemented with 2.22 μM 6-benzyladenine and 2.68 μM α-naphthaleneacetic acid and carbon sources (glucose or sucrose) at varying concentrations (0.1, 0.2, or 0.3 M). To assess the in vitro production of 20E, nodal segments were inoculated into Magenta® containers containing MS medium with different carbon sources (glucose, sucrose, or glucose + sucrose at 0.1 or 0.2 M) and placed in plastic bags with bacterial filters. Both experiments were composed of five repetitions for each treatment and analyzed after 30 d of culture. Multiple shoot formations were genotype-dependent when segments were cultivated on a medium supplemented with glucose or sucrose at 0.1 M, yielding 35 and 43 shoots per explant for Ac 4 and 4.4 and 2.8 shoots per explant for Ac 13, respectively. For the 20E content, significant effects were also observed among accessions and carbon sources. Ac 13 had the highest average 20E levels for both roots and leaves. Under the experimental conditions, Ac 4 had more favorable characteristics for large-scale multiplication than Ac 13, and glucose at 0.2 M was the best carbon source for the cultivation of Pfaffia, both for producing multiple shoots and for in vitro 20E production. This is the first report using a combination of auxin and cytokinin to enable effective Pfaffia in vitro axillary shoot proliferation from nodal explants