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Proton nuclear magnetic resonance (NMR) spectroscopy was used to follow glucose metabolism in Crithidia luciliae. Parasites were grown aerobically and anaerobically in culture, with glucose as the major carbon source and 1H NMR spectra were acquired for the cell free medium. The 1H NMR resonances of metabolites utilised and produced during cell growth were identified by difference spectroscopy, and quantitated from standard curves using 3-trimethylsilyl propionate-2,2,3,3-d4 sodium salt as an internal standard. The major metabolites produced by C. luciliae grown aerobically on 8 mM glucose were succinate, pyruvate, acetate and ethanol, in final concentrations in the media when the cells entered stationary phase of 8.5 +/- 0.5, 5.0 +/- 0.3, 2.1 +/- 0.2 and 2.5 +/- 0.6 mM, respectively. The production of succinate and pyruvate, but not acetate and ethanol, followed closely the growth curve of the parasites. Succinate was also measured enzymically and glucose using an autoanalyser. In both cases the results correlated well with the NMR data. The amounts of end products formed were greater than could be accounted for by the utilisation of glucose or any other metabolite observable in the 1H NMR spectra. There was approximately one extra atom of carbon for each molecule of succinate formed, supporting the view that succinate is produced via phosphoenolpyruvate carboxykinase and carbon dioxide fixation. Anaerobically the same major metabolites were produced, but with a decreased ratio of succinate to acetate and ethanol. The formation of glycerol from glucose was not observed under these conditions.

Abstract This paper presents a numerical study of the particle cluster behavior in a riser/downer reactor by means of combined computational fluid dynamics (CFD) and discrete element method (DEM), in which the motion of discrete particles is obtained by solving Newton's equations of motion and the flow of continuum gas by the Navier–Stokes equations. It is shown that the existence of particle clusters, unique to the solid flow behavior in such a reactor, can be predicted from this first principle approach. The results demonstrate that there are two types of clusters in a riser and downer: one is in the near wall region where the velocities of particles are low; the other is in the center region where the velocities of particles are high. While the extent of particle aggregation appears to be similar, the duration time for the first type in a downer is shorter than in a riser. Furthermore, it is demonstrated that the formation of clusters is affected by a range of variables related to operational conditions, particle properties, and bed properties and geometry. The increase of solid volume fraction, sliding and rolling friction between particles or between particles and wall, or damping coefficient can enhance the formation of clusters. The use of multi-sized particles can also promote the formation of clusters. But the increase of gas velocity or use of a wider bed can suppress the formation of clusters. The van der Waals force may enhance the formation of clusters when solid concentration is high but suppress the formation of clusters near the wall region when solid concentration is low.

Abstract The expansion of Sargassum muticum in the Danish estuary Limfjorden between 1984 and 1997 was followed by a decrease in abundance of native perennial macroalgae such as Halidrys siliquosa. Although commonly associated with the expansion of exotic species, it is unknown whether such structural changes affect ecosystem properties such as the production and turnover of organic matter and associated nutrients. We hypothesized that S. muticum possesses ‘ephemeral’ traits relative to the species it has replaced, potentially leading to faster and more variable turnover of organic matter. The biomass dynamics of S. muticum and H. siliquosa was therefore compared in order to assess the potential effects of the expansion of Sargassum. The biomass of Sargassum was highly variable among seasons while that of Halidrys remained almost constant over the year. Sargassum grew faster than Halidrys and other perennial algae and the annual productivity was therefore high (P/B = 12 year−1) and exceeded that of Halidrys (P/B = 5 year−1) and most probably also that of other perennial algae in the system. The major grazer on macroalgae in Limfjorden, the sea urchin Psammechinus miliaris, preferred Sargassum to Halidrys, but estimated losses due to grazing were negligible for both species and most of the production may therefore enter the detritus pool. Detritus from Sargassum decomposed faster and more completely than detritus from Halidrys and other slow-growing perennial macrophytes. High productivity and fast decomposition suggest that the increasing dominance of S. muticum have increased turnover of organic matter and associated nutrients in Limfjorden and we suggest that the ecological effects of the invasion to some extent resemble those imposed by increasing dominance of ephemeral algae following eutrophication.

In this paper, a comparison of power system frequency response is conducted for a simple modelled power system with primary frequency control being provided either by synchronous generators or by inverter-based Battery Energy Storage (BES) systems. Mathematical models of conventional governor and turbine are developed, representing conventional synchronous generator frequency control, and are used to illustrate system frequency response for a range of typical conventional generating units. A mathematical model of a power-electronics interfaced Li-ion BES system is developed and used to represent a non-synchronous inverter-based generator with primary frequency control capabilities. MATLAB/Simulink is used to build a model of a small power system, and simulations are carried out with at a range of typical conventional synchronous generating units with a nonsynchronous generating unit in the power system. The simulation results demonstrate that the BES can be used for primary frequency control providing a faster and better response. BES is also capable of almost eliminating frequency overshoot and reducing 70% of settling time while providing primary frequency control in power system with various types of conventional synchronous generating units and a nonsynchronous generating unit.

Abstract To improve the conversion efficiency of thermophotovoltaic devices, we designed a thermophotovoltaic system based on an InAs/InGaAsSb/GaSb three-junction tandem cell. The tandem cell can recover photons in the wavelength range of 200–3650 nm and therefore enhance the output power of the system. To further improve system performance, we designed a multilayer circular truncated cone metamaterial emitter matching the tandem cell. Existing TPV systems based on multi-junction tandem PV cells can achieve conversion efficiencies of 33.3%–41%, while the thermophotovoltaic system coupled with the multilayer circular truncated cone metamaterial can recover more photons of 1.44 mol/(m2·s) and achieve a higher conversion efficiency of 52.8% at 1773 K. The thermophotovoltaic system designed here demonstrates an extremely high energy conversion efficiency and has good application prospects.

Abstract The use of organic additives in zinc electroplating is reviewed with particular emphasis on the types of compounds used, the bath type for which they are most suited, and their function with respect to brightening and levelling action. Fundamental studies of the mode of action of these additives are also reviewed and comparisons are made with similar studies of nickel and copper electrodeposition. It is concluded that much more fundamental studies are required to fully explain the effects of additives. Further, the effect of codeposition of organic impurities on the corrosion resistance of electrodeposited zinc requires urgent study.

Abstract This study evaluates the performance of 75 clear-sky global irradiance models against 75 ground stations worldwide covering five major Koppen-Geiger climate classifications and overall global performance. After quality control, clear-sky detection and data-availability criteria, there are 4.36 million 1-min valid global horizontal irradiance (GHI) data points for evaluation. This study represents the most encompassing evaluation of its kind in terms of number of models assessed, number of ground stations used, most consistent selection of input variables in terms of temporal and spatial resolution, also using the most rigorous and fair performance assessment criteria and suitable ranking system. A statistically rigorous Principal Component Analysis (PCA) ranking procedure is proposed to replace the conventional ordering method based on single and simple statistics. In particular, it is demonstrated that all 13 error metrics contribute to the variance of GHI estimation and thus must all be accounted for in the ranking procedure. The best performing models in each climate zone of equatorial, arid, temperate, cold and polar are REST2v9.1, REST2v9.1, MAC2, REST2v5 and CLS, respectively. Globally, the top three performing models are MAC2, REST2v5, and REST2v9.1. Many models appear to suffer from over-fitting empirical relationships to training data, resulting in inconsistent worldwide performance. Furthermore, six different formulations of the Linke Turbidity factor (TL) are evaluated through its application to five clear-sky models that require it as an input. The best globally performing TL formulations are either by Ineichen or Gueymard when combined with four of the five Linke-dependent clear-sky models, whilst the Grenier formulation performs best with the Ineichen & Perez model. Significant performance variation is observed depending on the TL formulation selected, hence, careful selection is required for an optimal application. The model codes are available in R [1].

In this chapter, turbulent flow of water-based optimization (TFWO) inspired based on whirlpools created in turbulent flow of water is used to solve the maximum power point tracking (MPPT) of photovoltaic systems in partial shading conditions. The TFWO is used to determine the optimal duty cycle of the DC/DC converter with the objective of maximizing the extracted power of the photovoltaic system. The capability of proposed method is evaluated in different patterns of partial shading to achieve global optimal power. The simulation results showed that TFWO is able to track the global maximum power point (GMPP), successfully in PSC and also fast climate changing. The TFWO has a better tracking capability with faster tracking speed and accuracy than particle swarm optimization (PSO) in obtaining the GMPP. Moreover, the results indicate that the use of buck–boost converter led to faster and more accurate access to the global optimal point than the system equipped with boost converter. The results showed that photovoltaic system with boost converter cannot obtain global maximum power in climate changing condition and limited the efficiency of the MPPT algorithm, while the photovoltaic system with buck–boost converter could be tracked GMPP due to its wider operating area.

Abstract There are instances in remote areas where heat is being wasted, e.g., in internal combustion, engines, etc. Some of this heat can be recovered to produce distilled water in solar stills. The solar still replaces the cooling tower, ponds, or radiators normally used to control the engine temperature. The diesel cooling water in such a system remains separate from the saline water in the solar still. The advantages of using such a system compared with a conventional solar still are: 1. (a) water costs are very much reduced 2. (b) the area occupied is much less, i.e., about 1 5 th 3. (c) production has much less seasonal variation 4. (d) the efficiency of the solar still is improved due to the higher operating temperatures. From experiments conducted at Highett using a Mk VI solar still fitted with a simple heat exchanger and a separate electrically-heated source of hot water to simulate the waste heat, design data are not available for application to working systems. The information required to match a solar still to a diesel's cooling requirement is: 1. (a) engine efficiency 2. (b) hourly fuel consumption 3. (c) hourly solar radiation 4. (d) hourly ambient temperatures. A by-product of this work has been the production of a “solar water heater” which costs less than that of the cheapest conventional system. This “solar” hot water system uses a heat exchanger similar to what is used to transfer the waste heat to the saline water. It is envisaged to have hot water productions approximately the same as the distilled water productions. The influence of hot water production on the output of the waste heat solar still is discussed.