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The occurrence of siloxanes is a major barrier to use of biogas as renewable energy source, and removal of siloxanes from biogas before combustion is needed. The siloxane can be transformed into silicon dioxide (SiO) through the combustion process in engine, which will be deposited on the spark plug, cylinder, and impeller to form the silica layer, causing the wear and damage of the engine parts, and shorten the life of the engine and affect the utilization efficiency of the biogas. This paper reviewed some methods and technologies for siloxanes removal from biogas. There are three commercial available technologies to remove siloxanes: adsorption, absorption, and cryocondensation. Other newer technologies with better prospects for development also have made a research progress, including membrane, catalysts, biotrickling filters. This work introduces the source and characterization of siloxanes in biogas, reviews the scientific progress of siloxanes removal, and discusses the development direction and further research of removal siloxanes.

Quantification of brassinosteroids is essential and extremely important to study the molecular mechanisms of their physiological roles in plant growth and development. Herein, we present a simple, material and cost-saving high-performance method for determining endogenous brassinosteroids (BRs) in model plants. This new method enables simultaneous enrichment of a wide range of bioactive BRs such as brassinolide, castasterone, teasterone, and typhasterol with ion exchange solid-phase extraction and high-sensitivity quantitation of these BRs based on isotope dilution combined with internal standard approach. For routine analysis, the consumption of plant materials was reduced to one-twentieth of previously reported and the overall process could be completed within 1 day compared with previous 3 to 4 days. The strategy was validated by profiling BRs in different ecotypes and mutants of rice (Oryza sativa) and Arabidopsis (Arabidopsis thaliana), and the BR distributions in different model plants tissues were determined with the new method. The method allows plant physiologists to monitor the dynamics and distributions of BRs with 1 gram fresh weight of model plant tissues, which will speed up the process for the molecular mechanism research of BRs with these model plants in future work. Brassinosteroids (BRs) have been considered as the sixth class of endogenous plant hormones with wide occurrence across the plant kingdom (Bajguz and Tretyn, 2003). BRs play a key role in a variety of physiological processes, such as cell elongation, vascular differentiation , reproductive development, photomorphogenesis, stress tolerance, and so on (Hayat, 2010). Recently, it was found that BR deficiency could increase grain yield in rice (Oryza sativa) by more than 30%, which showed a food security-enhancing potential and guided new green revolution in the future (Sakamoto et al., 2006; Wu et al., 2008). Since BRs were first isolated and identified from rape (Brassica napus) pollen in 1970s (Mitchell et al., 1970; Grove et al., 1979), the natural occurrence of more than 60 BRs in a large quantity of plant species has been reported (Hayat, 2010). To date, research on the occurrence of BRs in different plants, physiological properties, and their action modes has made much progress (Fujioka and Yokota, 2003; Symons et al., 2008; Kim and Wang, 2010; Tang et al., 2010; Tong and Chu, 2012). However, so far, only limited information was obtained to understand the molecular mechanism of the physiological role of BRs. For example, although the biosynthetic pathway of C 28 BRs has been well established, the biosynthesis of C 27 and C 29 BRs remains unclear, and some intermedi-ates on their biosynthetic pathways still need to be elucidated (Noguchi et al., 2000; Fujita et al., 2006). The plant physiology research of BRs is speeded up by employing BR mutants on biosynthesis and signaling pathways (Yamamuro et al., 2000; Hong et al., 2003; Kwon and Choe, 2005; Tanabe et al., 2005); however, a simple, high-sensitivity screening, detection, and q...