Effect of substituents of twisted benzodiperylenediimides on non-fullerene solar cells

Twisted benzodiperylenediimides (TBDPDI) with large rigid conjugated core and strong absorption is regarded as an excellent acceptor in non-fullerene solar cells. Since side chains of semiconductors play a crucial role in the solar cells, TBDPDI acceptors with different side chains (1-ethylpropyl, C5; 2-ethylhexyl, C8; 1-pentylhexyl, C11; 2-octyldodecyl, C20; 1-undecyldodecyl, C23) were synthesized. In solution, TBDPDI compounds (C5, C11, and C23) with alkyl chains branched at 1-position show significantly different absorption profiles and fluorescence intensity with those (C8 and C20) branched at 2-position, due to stronger aggregation of the latter. Nevertheless, alkyl chains have little effect on the molecular orbital energy levels and optical band gaps, as verified by cyclic voltammetry and solid state absorption. Due to their complementary absorption and matchable energy levels with donor of PCE10, these acceptors and PCE10 were used together to fabricate bulk heterojunction (BHJ) solar cells. Because of inferior phase separation with large domain size around 100 nm and bulky insulated side chains, acceptors (C20 and C23) with long alkyl chains have the low electron mobility (μ_e) around 10⁻⁸ cm² V⁻¹ s⁻¹ and the low power conversion efficiency (PCE) of solar cells. TBDPDI (C11) with 1-pentylhexyl gives the highest PCE of 5.0% under the optimized condition, which is attributed to proper phase separation with domain size around 20 nm and highest μ_e of 10⁻⁶ cm² V⁻¹ s⁻¹.     

Low temperature cleanup combined with magnetic nanoparticle extraction to determine pyrethroids residue in vegetables oils

To quantify trace pesticide residue in vegetable oil rapidly, low temperature cleanup combined with magnetic nanoparticle based solid phase extraction was developed to determine eight pyrethroids in vegetable oils, including tetramethrin, fenpropathrin, cypermethrin, decamethrin, fenvalerate, acrinathrin, permethrin and bifenthrin. Polystyrene coated magnetic nanoparticles were synthesised by a modified chemical coprecipitation combined with emulsion polymerisation method. The nanoparticles were afterwards characterised by Fourier transform-infrared spectroscopy, X-ray diffraction, transmission electron microscopy as well as vibrating sample magnetometer, and successfully employed as adsorbents for the magnetic solid phase extraction of pyrethroids which were cleaned up using low temperature approach in advance. Critical impact factors on the efficiency of the extraction method such as the mass of adsorbents used, volume and type of eluent solvent, extraction time as well as elution time were optimised subsequently. Regression analysis of the calibration curves of the eight pyrethroids yielded satisfactory correlation coefficients within the range of 0.980–0.998. Limit of detection and limit of quantification were calculated to be between 0.0290-0.0658 and 0.0890–0.1994 ng g⁻¹, respectively. Intra-day and inter-day reproducibility at different concentration levels also produced satisfactory recovery rates of 83.18–112.79% with relative standard deviations not exceeding 10.84% and 12.01%, respectively, suggesting desirable stability of the proposed method.     

Harvest of electrical energy from fermented microalgal residue using a microbial fuel cell

The application of microalgal biomass for fermentation has been highlighted as a means of producing a range of value-added biofuels and chemicals. On the other hand, the microalgal residue from the fermentation process still contains as much as 50% organic contaminants, which can be a valuable substrate for further bioenergy recovery. In this study, a microbial fuel cell and automatic external load control by maximum power point tracking (MPPT) were implemented to harvest the electrical energy from waste fermented microalgal residue (FMR). The MFC with MPPT produced the highest amount of energy (1.82 kJ/L) compared to the other MFCs with fixed resistances: 0.98 (1000 Ω), 1.16 (500 Ω), and 1.17 kJ/L (300 Ω). The MFC with MPPT also showed the highest maximum power density (88.6 mW/m²) and COD removal efficiency (620.0 mg COD/L removal with 85% removal efficiency). The implementation of MPPT gained an approximate 12.9% energy yield compared to the previous fermentation stage. These results suggest that FMR can be an appropriate feedstock for electrical energy recovery using MFCs, and the combined fermentation and MFC system improves significantly the energy recovery and treatment efficiency from FMR.     

Performance evaluation of a solarized gas turbine system integrated to a high temperature electrolyzer for hydrogen production

In this paper, the performance of a solar gas turbine (SGT) system integrated to a high temperature electrolyzer (HTE) to generate hybrid electrical power and hydrogen fuel is analyzed. The idea behind this design is to mitigate the losses in the electrical power transmission and use the enthalpy of exhaust gases released from the gas turbine (GT) to make steam for the HTE. In this context, a GT system is coupled with a solar tower including heliostat solar field and central receiver to generate electrical power. To make steam for the HTE, a flameless boiler is integrated to the SGT system applying the SGT extremely high temperature exhaust gases as the oxidizer. The results indicate that by increasing the solar receiver outlet temperature from 800 K to 1300 K, the solar share increases from 22.1% to 42.38% and the overall fuel consumption of the plant reduces from 7 kg/s to 2.7 kg/s. Furthermore, flameless mode is achievable in the boiler while the turbine inlet temperature (TIT) is maintained at the temperatures higher than 1314 K. Using constant amounts of the SGT electrical power, the HTE voltage decreases by enhancing the HTE steam temperature which result in the augmentation of the overall hydrogen production. To increase the HTE steam temperature from 950 K to 1350 K, the rate of fuel consumption in the flameless boiler increases from 0.1 m/s to 0.8 m/s; however, since the HTE hydrogen production increases from 4.24 mol/s to 16 mol/s it can be interpreted that the higher steam temperatures would be affordable. The presented hybrid system in this paper can be employed to perform more thermochemical analyses to achieve insightful understanding of the hybrid electrical power-hydrogen production systems.     

Characterisation of acid-soluble collagen from skin and bone of bigeye snapper (Priacanthus tayenus)

The compositions and some properties of acid-soluble collagens (ASC) of the skin and bone of bigeye snapper, (Priacanthus tayenus) were investigated. The collagens were extracted with the yields of 10.94% and 1.59% on the basis of wet weight, from skin and bone, respectively. Similar electrophoretic patterns of collagens from the skin and bone were observed. Both collagens comprised two different α chains, α1 and α2 and were classified as type I collagen. However, peptide maps of collagen from the skin and bone of bigeye snapper, digested by V8 protease and lysyl endopeptidase, revealed differences between collagens from skin and bone, and both were completely different from those of calf skin collagen. Collagen rehydrated in acetic acid had lower T_max and enthalpy than those rehydrated in deionised water, suggesting a conformational change caused by acid. Collagens form the skin and bone had the highest solubility at pH 2 and 5, respectively. No changes in solubility were observed in the presence of NaCl up to 3% (w/v). However, a sharp decrease in solubility was found with NaCl above 3% (w/v).     

Free,esterified, and insoluble-bound phenolic acids in white and red Korean ginsengs (Panax ginseng C.A. Meyer)

Phenolic acids of dried white and red ginsengs were extracted and fractionated into free, esterified, and insoluble-bound forms. The contents of individual phenolic acids in different forms were quantified by gas–liquid chromatography. Identification of all phenolic acids was confirmed by gas chromatography–mass spectrometry and comparison of gas chromatographic retention times. Twelve different phenolic acids as free, esterified, and insoluble-bound forms were identified in Korean ginsengs. Total phenolic acids in white and red ginsengs were 27.2 and 26.8 mg/100 g, respectively. Seven free phenolic acids were identified and their total contents in white and red ginsengs were 4.70 and 4.14 mg/100 g, respectively. trans-Ferulic acid was the predominant free phenolic acid, representing 47.9 and 57.7% of total free phenolic acids in white and red ginsengs, respectively. Esterified phenolic acids represented 71.9 and 77.1% of total phenolic acids in white and red ginsengs, respectively. The most predominant esterified phenolic acids were cis-ferulic acid and trans-ferulic acid. Total insoluble-bound phenolic acid contents in white and red ginsengs were 2.93 and 1.99 mg/100 g, respectively. Ferulic acid (cis and trans isomers) was also the major insoluble-bound phenolic acids. This paper represents the first report of systematic identification and quantification of phenolic acids in different forms in white and red Korean ginsengs.     

Cholesterol-lowering food additives: lipase-catalysed preparation of phytosterol and phytostanol esters

We have shown recently that plant steryl and stanyl esters, used as plasma cholesterol-lowering food supplements, can be efficiently prepared from the sterols and stanols via lipase-catalysed esterification with fatty acids and transesterification with fatty acid methyl esters or triacylglycerols [Weber, N., Weitkamp, P., & Mukherjee, K. D. (2001). Journal of Agricultural and Food Chemistry, 49, 67–71]. In continuation of this work, sterols contained in three different steam distillates obtained from rapeseed oil by conventional deodorization or from rapeseed oil or a mixture of soybean and rapeseed oils by physical refining have been converted to a high degree in situ to the corresponding long-chain acyl esters via esterification and/or transesterification with fatty acids and/or triacylglycerols using lipase from Candida rugosa as biocatalyst in vacuo (20–40 mbar) at 40 °C. The steryl esters formed were purified to ⩾90% by deacidification, flash chromatography on silica gel and solvent fractionation using acetone-water (9:1,v/v).