Binary Plant Research Articles

Setting up a platform for plant-based influenza virus vaccine production in South Africa

BackgroundDuring a global influenza pandemic, the vaccine requirements of developing countries can surpass their supply capabilities, if these exist at all, compelling them to rely on developed countries for stocks that may not be available in time. There is thus a need for developing countries in general to produce their own pandemic and possibly seasonal influenza vaccines. Here we describe the development of a plant-based platform for producing influenza vaccines locally, in South Africa. Plant-produced influenza vaccine candidates are quicker to develop and potentially cheaper than egg-produced influenza vaccines, and their production can be rapidly upscaled. In this study, we investigated the feasibility of producing a vaccine to the highly pathogenic avian influenza A subtype H5N1 virus, the most generally virulent influenza virus identified to date. Two variants of the haemagglutinin (HA) surface glycoprotein gene were synthesised for optimum expression in plants: these were the full-length HA gene (H5) and a truncated form lacking the transmembrane domain (H5tr). The genes were cloned into a panel of Agrobacterium tumefaciens binary plant expression vectors in order to test HA accumulation in different cell compartments. The constructs were transiently expressed in tobacco by means of agroinfiltration. Stable transgenic tobacco plants were also generated to provide seed for stable storage of the material as a pre-pandemic strategy.ResultsFor both transient and transgenic expression systems the highest accumulation of full-length H5 protein occurred in the apoplastic spaces, while the highest accumulation of H5tr was in the endoplasmic reticulum. The H5 proteins were produced at relatively high concentrations in both systems. Following partial purification, haemagglutination and haemagglutination inhibition tests indicated that the conformation of the plant-produced HA variants was correct and the proteins were functional. The immunisation of chickens and mice with the candidate vaccines elicited HA-specific antibody responses.ConclusionsWe managed, after synthesis of two versions of a single gene, to produce by transient and transgenic expression in plants, two variants of a highly pathogenic avian influenza virus HA protein which could have vaccine potential. This is a proof of principle of the potential of plant-produced influenza vaccines as a feasible pandemic response strategy for South Africa and other developing countries.

Thermo-fluid dynamics preliminary design of turbo-expanders for ORC cycles

Selecting the best design options for turbo-expanders to be used in Organic Rankine Power Cycle applications is a difficult task, with special reference to the low-temperature applications (T<150°C) which are relevant for specific fields in rapid development (geothermal binary plants, solar thermal energy conversion systems). A wide literature exists on the optimal selection of the working fluid from the thermodynamic point of view; while the fluid dynamics design is often based on the direct application of CFD techniques, without a preliminary screening on the issues of application of a specific working fluid. In practice, however, the selection of the working fluid has relevant effects both on the cycle thermodynamics and on the fluid dynamic losses and turbo-expander efficiency. Referring to a radial-type turbo-expander, a comparison of different working fluids is presented and discussed.

Comparative performance analysis of various binary coded PSO algorithms in multivariable PID controller design

In this paper, comparative performance analysis of various binary coded PSO algorithms on optimal PI and PID controller design for multiple inputs multiple outputs (MIMO) process is stated. Four algorithms such as modified particle swarm optimization (MPSO), discrete binary PSO (DBPSO), modified discrete binary PSO (MBPSO) and probability based binary PSO (PBPSO) are independently realized using MATLAB. The MIMO process of binary distillation column plant, described by Wood and Berry, with and without a decoupler having two inputs and two outputs is considered. Simulations are carried out to minimize two objective functions, that is, time integral of absolute error (ITAE) and integral of absolute error (IAE) with single stopping criterion for each algorithm called maximum number of fitness evaluations. The simulation experiments are repeated 20 times with each algorithm in each case. The performance measures for comparison of various algorithms such as mean fitness, variance of fitness, and best fitness are computed. The transient performance indicators and computation time are also recorded. The inferences are made based on analysis of statistical data obtained from 20 trials of each algorithm and after having comparison with some recently reported results about same MIMO controller design employing real coded genetic algorithm (RGA) with SBX and multi-crossover approaches, covariance matrix adaptation evolution strategy (CMAES), differential evolution (DE), modified continuous PSO (MPSO) and biggest log modulus tuning (BLT). On the basis of simulation results PBPSO is identified as a comparatively better method in terms of its simplicity, consistency, search and computational efficiency.

The thermodynamic efficiency of the condensing process circuits of binary combined-cycle plants with gas-assisted heating of cycle air

The thermal efficiencies of condensing-type circuits of binary combined-cycle plants containing one, two, and three loops with different pressure levels and equipped with a GTE-160 (V94.2) gas turbine unit, and with preheating of cycle air are analyzed by way of comparison in a wide range of initial steam pressures. The variation of the combined-cycle plant efficiency, stream wetness, conditional overall heating surface of the heat-recovery boiler, and other parameters is presented.

Thermodynamic modeling of power plants based on solid oxide fuel cells

A mathematical model of a solid oxide fuel cell is presented for investigation of the thermodynamic cycles of power plants. The model is one-dimensional in two directions: in the direction of fuel flow in the supply channel and perpendicular to the contact planes of the electrolyte and electrodes. Electrochemical reactions are assumed to run in the area of nonzero width adjoining the electrolyte. Natural gas is taken as a fuel, and its internal steam conversion in a porous anode is considered. Heat transfers are governed by the model of a generalized heat exchanger, described by accumulation curves of temperature-versus-power for heat sources and sinks. A binary plant with a fuel cell at atmospheric pressure and a subatmospheric gas-turbine bottoming is considered as an example.

BAC‐recombineering for studying plant gene regulation: developmental control and cellular localization of SnRK1 kinase subunits

Recombineering, permitting precise modification of genes within bacterial artificial chromosomes (BACs) through homologous recombination mediated by lambda phage-encoded Red proteins, is a widely used powerful tool in mouse, Caenorhabditis and Drosophila genetics. As Agrobacterium-mediated transfer of large DNA inserts from binary BACs and TACs into plants occurs at low frequency, recombineering is so far seldom exploited in the analysis of plant gene functions. We have constructed binary plant transformation vectors, which are suitable for gap-repair cloning of genes from BACs using recombineering methods previously developed for other organisms. Here we show that recombineering facilitates PCR-based generation of precise translational fusions between coding sequences of fluorescent reporter and plant proteins using galK-based exchange recombination. The modified target genes alone or as part of a larger gene cluster can be transferred by high-frequency gap-repair into plant transformation vectors, stably maintained in Agrobacterium and transformed without alteration into plants. Versatile application of plant BAC-recombineering is illustrated by the analysis of developmental regulation and cellular localization of interacting AKIN10 catalytic and SNF4 activating subunits of Arabidopsis Snf1-related (SnRK1) protein kinase using in vivo imaging. To validate full functionality and in vivo interaction of tagged SnRK1 subunits, it is demonstrated that immunoprecipitated SNF4-YFP is bound to a kinase that phosphorylates SnRK1 candidate substrates, and that the GFP- and YFP-tagged kinase subunits co-immunoprecipitate with endogenous wild type AKIN10 and SNF4.

Relevant Elements of a Maize γ-Zein Domain Involved in Protein Body Biogenesis

The N-terminal proline-rich domain of γ-zein (Zera) plays an important role in protein body (PB) formation not only in the original host (maize seeds) but in a broad spectrum of eukaryotic cells. However, the elements within the Zera sequence that are involved in the biogenesis of PBs have not been clearly identified. Here, we focused on amino acid sequence motifs that could be involved in Zera oligomerization, leading to PB-like structures in Nicotiana benthamiana leaves. By using fusions of Zera with fluorescent proteins, we found that the lack of the repeat region (PPPVHL)(8) of Zera resulted in the secretion of the fusion protein but that this repeat by itself did not form PBs. Although the repeat region containing eight units was the most efficient for Zera self-assembly, shorter repeats of 4-6 units still formed small multimers. Based on site-directed mutagenesis of Zera cysteine residues and analysis of multimer formation, we conclude that the two N-terminal Cys residues of Zera (Cys(7) and Cys(9)) are critical for oligomerization. Immunoelectron microscopy and confocal studies on PB development over time revealed that early, small, Zera-derived oligomers were sequestered in buds along the rough ER and that the mature size of the PBs could be attained by both cross-linking of preformed multimers and the incorporation of new chains of Zera fusions synthesized by active membrane-bound ribosomes. Based on these results and on the behavior of the Zera structure determined by molecular dynamics simulation studies, we propose a model of Zera-induced PB biogenesis.

Technical and economical analysis of a solar–geothermal hybrid plant based on an Organic Rankine Cycle

A combined concentrating solar power system and a geothermal binary plant based on an Organic Rankine Cycle (ORC) is analyzed. Given a supercritical ORC, designed for the optimal utilization of an intermediate enthalpy geothermal source, a solar parabolic trough field was included in the plant, introducing an additional high temperature heat source for the cycle and increasing power production. The off-design performance analysis of the power cycle was performed first. An hour-by-hour simulation was then carried out to estimate the yearly production using a detailed solar field model. Finally, a differential economic analysis was performed to determine the cost of the additional electricity generated with the solar source. On the basis of the current cost of solar collectors, levelized costs of electricity of 145–280 €/MWh were obtained depending on the location of the plant: a competitive value with respect to large, stand-alone concentrating solar power plants.

Sensitivity analysis of steam power plant-binary cycle

Abstract This paper analyses a steam power – two-stage binary cycle plant (SPP–2BCP), in which low temperature waste heat from a conventional steam power plant can be efficiently utilized to generate electricity by installing a bottoming binary cycle. The result from a previous calculation on the installation of binary cycle technology on a Steam Power Plant (SPP) with n-Pentane working fluid indicates an increase in plant efficiency of about 9%. The purpose of this study is to analyze the sensitivity of performance of the binary cycle system against variations in the SPP operational load and the condenser’s cooling water temperature. The calculation is conducted on SPP load variations of 25%, 50%, 75% and 100%, inlet turbine pressure variations of 5 bar–30 bar, and inlet turbine temperature variations of 125 °C up to 235 °C. Each of these is also analyzed with ambient cooling water temperatures of 30 °C–37 °C. The results of the analysis indicate that the performance of this binary cycle SPP degrades slightly with SPP load, turbine inlet temperature, and turbine inlet pressure variations and with cooling water variations.

Covariance matrix adaptation evolution strategy based design of centralized PID controller

In this paper, design of centralized PID controller using Covariance Matrix Adaptation Evolution Strategy (CMAES) is presented. Binary distillation column plant described by Wood and Berry (WB) having two inputs and two outputs and by Ogunnike and Ray (OR) having three inputs and three outputs are considered for the design of multivariable PID controller. Optimal centralized PID controller is designed by minimizing IAE for servo response with unit step change. Simulations are carried out using SIMULINK-MATLAB software. The statistical performances of the designed controllers such as best, mean, standard deviations of IAE and average functional evaluations for 20 independent trials. For the purpose of comparison, recent version of real coded Genetic Algorithm (RGA) with simulated binary crossover (SBX) and conventional BLT method are used. In order to validate the performance of optimal PID controller for robustness against load disturbance rejection, load regulation experiment with step load disturbance is conducted. Also, to determine the performance of optimal PID controller for robustness against model uncertainty, servo and load response with +20% variations in gains and dead times is conducted. Simulation results reveal that for both OR and WB systems, CMAES designed centralized PID controller is better than other methods and also it is more robust against model uncertainty and load disturbance.

Optimal design of binary cycle power plants for water-dominated, medium-temperature geothermal fields

Exploitation of lower temperature, water-dominated geothermal fields is analyzed, and a methodology for optimizing geothermal binary plants is discussed. The geothermal fluid inlet temperatures considered are in the 110–160 °C range, while the return temperature of the brine is assumed to be between 70 and 100 °C. The analysis shows that the brine specific consumption, ranging from 20 to 120 kg s −1 for each net MW produced, and the efficiency of the plants, ranging from 20% to 45% in terms of Second Law efficiency, are dictated mainly by the combination of the brine inlet temperature, the brine rejection temperature and the energy conversion cycle being used. For given operating conditions and with correct matching between working fluid and energy conversion cycle, it is possible to obtain very similar performances in a number of different cases. It is shown that optimization of the plant can yield improvements of up to 30–40% in terms of reduction of brine specific consumption compared to conventional design.

Efficiency improvement for geothermal power generation to meet summer peak demand

Geothermal power is an important part of New Zealand's renewable electricity supply due to its attractive cost and reliability. Modular type binary cycle plants have been imported and installed in various geothermal fields in New Zealand, with plans for further expansion. Power output of these plants deteriorates in the summer because plant efficiency depends directly on the geothermal resource and the ambient temperature. As these plants normally use air-cooled condensers, incorporating a water-augmented air-cooled system could improve the power output in summer thereby matching the peak air-conditioning demand. In this work, power generation for the Rotokawa plant was characterized using a similar plant performance and local weather. The improved performance was modelled for retrofit with a wet-cooling system. Maximum generation increase on the hottest day could be 6.8%. The average gain in power over the summer, November–February, was 1.5%, and the average gain for the whole year was 1%. With current binary unit generation capacity at the Rotokawa plant of 35 MW, investment in a water-augmented air-cooled system could provide 2 MW of peak generation on the hottest days. This investment in efficiency is found to compare favourably to other supply options such as solar PV, wind or gas.

Utilisation of geothermal resources

For centuries, geothermal energy has been used for bathing, cooking and space heating. More recently, district heating, industrial processing and geothermal heat pumps have become part of the direct-use mix. Geothermal electric power generation began in Italy in 1904, with the first commercial plant operational in 1913. Presently, the total installed global capacity for direct use is 29 000 MWt, producing 76 000 GW h/year in 72 countries; the installed capacity for electric power is 9700 MWe, generating 60 000 GW h/year in 24 countries. Recent trends are to maximise the use of geothermal resources in a combined heat and power project. Geothermal resources of around 100°C have been used in binary (organic Rankine) cycle plants and then cascaded for district heating. Geothermal energy is considered to be both renewable and sustainable as a ‘green energy’ resource, but certain environmental aspects must be considered and mitigated.

Evolutionary algorithms based design of multivariable PID controller

In this paper, performance comparison of evolutionary algorithms (EAs) such as real coded genetic algorithm (RGA), modified particle swarm optimization (MPSO), covariance matrix adaptation evolution strategy (CMAES) and differential evolution (DE) on optimal design of multivariable PID controller design is considered. Decoupled multivariable PI and PID controller structure for Binary distillation column plant described by Wood and Berry, having 2 inputs and 2 outputs is taken. EAs simulations are carried with minimization of IAE as objective using two types of stopping criteria, namely, maximum number of functional evaluations (Fevalmax) and Fevalmax along with tolerance of PID parameters and IAE. To compare the performances of various EAs, statistical measures like best, mean, standard deviation of results and average computation time, over 20 independent trials are considered. Results obtained by various EAs are compared with previously reported results using BLT and GA with multi-crossover approach. Results clearly indicate the better performance of CMAES and MPSO designed PI/PID controller on multivariable system. Simulations also reveal that all the four algorithms considered are suitable for off-line tuning of PID controller. However, only CMAES and MPSO algorithms are suitable for on-line tuning of PID due to their better consistency and minimum computation time.

Closed versus open cycle energy recovery from solid oxide fuel cells

A computer model of a solid oxide fuel cell (SOFC) was implemented with a number of operational options to evaluate the best use of the cell waste heat. The simplest solution for heat recovery is represented by adopting a pressurized fuel cell with the eventual expansion of the exhaust stream in a gas turbine. Other alternatives feature the adoption of various closed cycle recovery systems: a standard steam cycle, an inter-refrigerated helium cycle, and an advanced binary cycle. Assuming a fuel energy input of 100 MW, the overall efficiency of a hybrid cell was computed, which was much higher than that of a small capacity (100 kW) existing plant (67 versus ∼53 per cent). Such high efficiency hybrid SOFC systems were taken as the reference to evaluate the performance of alternate options. Reclaiming the cell waste heat by means of a subcritical steam cycle yields a performance similar to that of a hybrid system. Similar results are obtained resorting to a closed helium cycle. Advanced binary cycles, using either potassium or cesium as working fluids, were extensively investigated in view of achieving a superior overall performance. The hot, clean stream exhausted by the fuel cell is recognized as an ideal heat source for a binary plant. The SOFC-binary cycle system was fully optimized yielding top efficiencies ∼74 per cent and an additional power output of ∼45 per cent of the cell rating (30 per cent in the case of the hybrid system). The excellent efficiency of a binary cycle combined with the large amount of oxygen that is available in the cell exhaust flow suggests that a supplementary firing of the fuel could improve the overall merit of the system. Burning 75 per cent of the additional natural gas, for example, reduces the total efficiency to a level of that of a hybrid system but makes available an extra power 1.35 times greater than the fuel cell capacity. Pushing further this concept, the fuel cell could become an auxiliary equipment of a binary cycle.

Verification of color vegetation indices for automated crop imaging applications

An accurate vegetation index is required to identify plant biomass versus soil and residue backgrounds for automated remote sensing and machine vision applications, plant ecological assessments, precision crop management, and weed control. An improved vegetation index, Excess Green minus Excess Red (ExG − ExR) was compared to the commonly used Excess Green (ExG), and the normalized difference (NDI) indices. The latter two indices used an Otsu threshold value to convert the index near-binary to a full-binary image. The indices were tested with digital color image sets of single plants grown and taken in a greenhouse and field images of young soybean plants. Vegetative index accuracies using a separation quality factor algorithm were compared to hand-extracted plant regions of interest. A quality factor of one represented a near perfect binary match of the computer extracted plant target compared to the hand-extracted plant region. The ExG − ExR index had the highest quality factor of 0.88 ± 0.12 for all three weeks and soil-residue backgrounds for the greenhouse set. The ExG + Otsu and NDI − Otsu indices had similar but lower quality factors of 0.53 ± 0.39 and 0.54 ± 0.33 for the same sets, respectively. Field images of young soybeans against bare soil gave quality factors for both ExG − ExR and ExG + Otsu around 0.88 ± 0.07. The quality factor of NDI + Otsu using the same field images was 0.25 ± 0.08. The ExG − ExR index has a fixed, built-in zero threshold, so it does not need Otsu or any user selected threshold value. The ExG − ExR index worked especially well for fresh wheat straw backgrounds, where it was generally 55% more accurate than the ExG + Otsu and NDI + Otsu indices. Once a binary plant region of interest is identified with a vegetation index, other advanced image processing operations may be applied, such as identification of plant species for strategic weed control.

PBINPLUS/ARS: An Improved Plant Transformation Vector Based on pBINPLUS

Binary plant transformation vectors are widely used for introduction of transgenes into plants via Agrobacterium tumefaciens-mediated transformation. We report the construction of a binary plant vector pBINPLUS/ARS based on the pBINPLUS vector. Improvements introduced into pBINPLUS/ARS include the use of nonproprietary (ubiquitin-3 gene of Solanum tuberosum) promoter and terminator sequences for transcription of the NptII selectable marker and introduction of rare 8-bp restriction enzyme sites flanking both the NptII coding sequence (PmeI) and the entire selectable marker gene (FseI). This vector offers all of the advantages of its predecessor pBINPLUS and its helper plasmid pUCAP, which use the proprietary nopaline synthase promoter and terminator, while allowing for facile modification of selectable marker sequences in complex binary vector constructs. pBINPLUS/ARS has been used to introduce transgenes into potato and other crop species and is available to all researchers in academic, government, and industrial laboratories for proof-of-principle and commercial applications.

Frequency distribution models for spatial patterns of vegetation abundance

In a plant community, measurements of the number of plant individuals, the number of binary occurrences, plant cover, and biomass per unit area have frequently been used to explain species composition and spatial variation. Studies have shown that frequency distribution can be expressed in several ways: the number of individuals can be expressed using the negative binomial distribution, the number of binary occurrences can be expressed using the beta-binomial distribution, plant cover can be expressed by the beta distribution, and biomass by the gamma distribution. In this study, we have mathematically clarified the relationships between these distributions and their biological relevance. We have also defined a spatial heterogeneity index for each of the above four methods of measurement. For each of these four distribution patterns, several-fitted examples of plant populations or communities, obtained from grassland surveys, are provided.

Ideal thermal efficiency for geothermal binary plants

The Carnot cycle is reviewed as to its appropriateness to serve as the ideal model for geothermal binary power plants. It is shown that the Carnot cycle sets an unrealistically high upper limit on the thermal efficiency of these plants. A more useful model is the triangular (or trilateral) cycle because binary plants operating on geothermal hot water use a non-isothermal heat source. The triangular cycle imposes a lower upper bound on the thermal efficiency and serves as a more meaningful ideal cycle against which to measure the performance of real binary cycles. Carnot and triangular cycle efficiencies are contrasted and the thermal efficiencies of several actual binary cycles are weighed against those of the ideal triangular cycle to determine their relative efficiencies. It is found that actual binary plants can achieve relative efficiencies as high as 85%. The paper briefly discusses cycles using two-phase expanders that in principle come close to the ideal triangular cycle.

Unit 5 bottoming binary plant at Miravalles geothermal field, Costa Rica: Planning, design, performance and impact

The Miravalles geothermal power station in Costa Rica is described before and after the addition of Unit 5, a bottoming binary power plant. The early planning and design alternatives for the new unit, the bids, the selection criteria followed, and details of the final design, including the unique asymmetrical piping layout, are discussed. The performance of Unit 5 is assessed both on a cycle and an overall plant basis. Thermal and utilization efficiencies are reported. The pentane power cycle is shown to scale in pressure–enthalpy and temperature–entropy diagrams. The analysis of data on 2 years of operation indicates that, during its acceptance tests, Unit 5 showed a net overall plant thermal efficiency in excess of 16%. Much of the operating data are burdened with such scatter and uncertainty as to render conclusions difficult to draw. However, recent, more reliable data have revealed a drop-off in efficiency that was likely caused by changes in brine supply flow rate relative to the design value. The average capacity factor over the plant's first 26 months was 94% and at least one of the two modules was in operation 96% of the time. Unit 5 raised the overall Miravalles utilization efficiency by about 13% without the need for additional wells.