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Power Scavenging and Optical Absorbance Analysis of Photosynthetically Active Protoplasts
Abstract
Plants and photosynthetic bacteria hold protein molecular complexes that can efficiently harvest photons. This article presents fundamental studies to harness photochemical activities of photosynthetically active protoplast extracted from Arabidopsis plants. The conversion of photonic energy into electrical energy was characterized in the presence and absence of light. The photoinduced reactions of photosynthesis were measured using a patch clamp measurement system at a constant voltage. The optical characterization was also performed on the extracted protoplast. It showed absorption bands at a number of wavelengths. The current-voltage measurements done on protoplast extracts showed two orders of magnitude increase in current from dark to light conditions. The absorbance measurements showed very large bandwidth for extracted protoplasts. The analysis of the optical data measurements showed that protein complexes obtained from photosynthetic cells overcame the limitation of traditional organic solar cells that cannot absorb light in the visible-near infrared spectrum. The demonstration of electrical power scavenging from the protoplast of the plant can open avenues for bio- inspired and bio-derived power with better quantum electrical efficiency. [DOI: 10.1115/1.4007657]
... While inorganic lead halides have been studied since the nineteenth century [2,3] and organic-inorganic halides have been of interest since the early twentieth century, the first perovskite-structured hybrid halide compounds was reported in a study by Weber in 1978. In recent years, the use of organo-mineral perovskite compounds as light absorbers in the production of solar cells has been dramatically increased [4][5][6][7][8][9][10]. The materials with a chemical structure of ABX3 are called perovskite, in which A is an organic or inorganic cation (CH 3 NH 3+ , CH (NH 2 ) 2+ , Cs + ), B is an inorganic cation (Pb 2+ , Sn 2+ , Ge 2+ ), and X is an inorganic anion or polyanion (Halides Cl -, Br -, I -) ( Figure 1). ...
Perovskite Solar cells have recently been considered to be an auspicious candidate for the advancement of future photovoltaic research. A power conversion efficiency (PCE) as high as 22% has been reported to be reached, which can be obtained through an inexpensive and highthroughput solution process. Modelling and simulation of these cells can provide deep insights into their fundamental mechanism of performance. In this paper, two different perovskite solar cells are designed by using COMSOL Multiphysics to optimize the thickness of each layer, and the overall thickness of the cell. Electric potential, electron and hole concentrations, generation
rate, open–circuit voltage, short circuit current, and the output power were calculated. Finally, power conversion efficiency (PCE) of 20.7 % and 26.1 % were predicted. Afterwards, according to the simulation results, the role of the hole transport layer (HTL) was investigated and the optimum thickness of the perovskite was measured to be 200 nm for both cells. Therefore, the Spin Coating settings were selected so that a coating with this thickness for cell 1 is deposited. In order to compare the performance of HTM layer, solar cells with a Spiro-OMeTAD HTM, and without the HTM layer in their structure were fabricated. According to the obtained photovoltaic properties, the solar cell made with Spiro-OMeTAD has a more favourable open-circuit voltage (VOC), short circuit current density (Jsc), fill factor (FF), and power conversion efficiency (PCE) compared to the cell without HTM layer. Also, hysteresis depends strongly on perovskite grain
size, because large average grain size will lead to an increase in the grain’s contact surface area and a decrease in the density of grain boundaries. Finally, according to the results, it was concluded that, in the presence of a hole transport layer, ion transfer was better and ion
accumulation was less intense, and therefore, the hysteresis decreases.
Plants and photosynthetic bacteria contain protein-molecular complexes that harvest photons with nearly optimum quantum yield and an expected power conversion efficiency exceeding 20%. In this work, we demonstrate the integration of electrically active photosynthetic protein-molecular complexes in solid-state devices, realizing photodetectors and photovoltaic cells with internal quantum efficiencies of approximately 12%. Electronic integration of devices is achieved by self-assembling an oriented monolayer of photosynthetic complexes, stabilizing them with surfactant peptides, and then coating them with a protective organic semiconductor.
Decline in fossil fuel resources along with high crude oil prices generated attention
toward the development of fuel from alternate sources. Such fuel should be economically
attractive and performance competent in order to replace the fossil fuel. Mustard oil from
Indian mustard, Brassica campestris, is commonly used for cooking in Indian households
and restaurants. Cooking produces spent mustard oil waste, which is generally drained
as garbage. We explored the possibility of using such spent mustard oil for making
biodiesel. Transesterification of spent oil was carried out using methanol and sulfuric
acid (95%) as catalysts followed by bubble washing. Clear biodiesel was obtained from
esterified oil after five bubble washings. Methyl ester formations were calculated by
measuring its density at 15°C and viscosity at 40°C and were found to be 89 g/cm3 and
4.83 mm2 / s, respectively. Studies on engine performance were conducted using a Prony
brake internal combustion (IC) diesel engine using various blending ratios of biodiesel
with commercial diesel. The fuel blends were evaluated for parameters such as speed of
engine, fuel consumption, and torque against pure diesel. Brake power, specific fuel
consumption, and thermal efficiency were also measured. The results indicate that dual
fuel with a blend of 8% biodiesel yielded good efficiency in the IC-diesel engines without
the need for making any modifications in the engine
We report measurements of the photovoltaic response of two‐layer photocells formed with layers of the conjugated polymer poly(phenylenevinylene), PPV and fullerene, C 60 , formed between indium‐tin oxide and aluminum electrodes. Peak quantum efficiencies of up to ∼9% (electrons collected per incident photon) were measured under short‐circuit conditions. We model the photovoltaic response as arising from excitons photogenerated in the PPV layer which are able to diffuse to the interface with the C 60 layer where they are ionized. We obtain a value for the exciton diffusion range of 7±1 nm, both from the spectral response and from the absolute efficiency. We demonstrate that the branching ratio for the creation of singlet excitons from absorbed photons is close to unity. © 1996 American Institute of Physics.
This work demonstrates the integration of the energy-transducing proteins bacteriorhodopsin (BR) from Halobacterium halobium and cytochrome c oxidase (COX) from Rhodobacter sphaeroides into block copolymeric vesicles towards the demonstration of coupled protein functionality. An ABA triblock copolymer-based biomimetic membrane possessing UV-curable acrylate endgroups was synthesized to serve as a robust matrix for protein reconstitution. BR-functionalized polymers were shown to generate light-driven transmembrane pH gradients while pH gradient-induced electron release was observed from COX-functionalized polymers. Cooperative behaviour observed from composite membrane functionalized by both proteins revealed the generation of microamp-range currents with no applied voltage. As such, it has been shown that the fruition of technologies based upon bio-functionalizing abiotic materials may contribute to the realization of high power density devices inspired by nature.
Oligomer-based DNA Affymetrix GeneChips representing about one-third of Arabidopsis (Arabidopsis thaliana) genes were used to profile global gene expression in a single cell type, guard cells, identifying 1309 guard cell-expressed genes. Highly pure preparations of guard cells and mesophyll cells were isolated in the presence of transcription inhibitors that prevented induction of stress-inducible genes during cell isolation procedures. Guard cell expression profiles were compared with those of mesophyll cells, resulting in identification of 64 transcripts expressed preferentially in guard cells. Many large gene families and gene duplications are known to exist in the Arabidopsis genome, giving rise to redundancies that greatly hamper conventional genetic and functional genomic analyses. The presented genomic scale analysis identifies redundant expression of specific isoforms belonging to large gene families at the single cell level, which provides a powerful tool for functional genomic characterization of the many signaling pathways that function in guard cells. Reverse transcription-PCR of 29 genes confirmed the reliability of GeneChip results. Statistical analyses of promoter regions of abscisic acid (ABA)-regulated genes reveal an overrepresented ABA responsive motif, which is the known ABA response element. Interestingly, expression profiling reveals ABA modulation of many known guard cell ABA signaling components at the transcript level. We further identified a highly ABA-induced protein phosphatase 2C transcript, AtP2C-HA, in guard cells. A T-DNA disruption mutation in AtP2C-HA confers ABA-hypersensitive regulation of stomatal closing and seed germination. The presented data provide a basis for cell type-specific genomic scale analyses of gene function.
The detailed balance method for calculating the radiative recombination limit to the performance of solar cells has been extended to include free carrier absorption and Auger recombination in addition to radiative losses. This method has been applied to crystalline silicon solar cells where the limiting efficiency is found to be 29.8 percent under AM1.5, based on the measured optical absorption spectrum and published values of the Auger and free carrier absorption coefficients. The silicon is assumed to be textured for maximum benefit from light-trapping effects.
Most of the current production cost in algae biodiesel plants utilizing photobioreactors comes from the high energy required for pumping, CO 2 transfer, mixing, and harvesting. Since pumping affects the mixing and CO 2 transfer, which are the main factors in algae productivities, solutions to reduce the required energy for pumps can significantly make algae biodiesel production more economically feasible. An investigation on the effect of Scenedesmus obliquus's growth from low to high biomass concentration inside a horizontal tubular photobioreactor to determine the impact that it has on hydrodynamic performances, which will affect cost and production efficiency, was performed. As the biomass concentration increased, the algal culture was found to remain Newtonian. Additionally, the biomass concentration (expressed in cell density) was found to have lower viscosity even at the highest concentrations evaluated at 2.48 × 10 8 cell/ml (1.372 × 10 -3 ± 1.32 × 10 -4 Pa s) compared to the Modified Bold's 3N medium (1.408 × 10 -3 ± 9.41 × 10 -5 Pa s). Furthermore, the total energy consumption does not appear to depend on the S. obliquus biomass concentrations, but rather on the medium the algae grows in. The rheological properties of autotrophic algae will not have significant impact on energy requirements until technology improves so that the concentrations reach those of heterotrophic algae.
Thermodynamic, geometric, and economic models are developed for a proton exchange membrane (PEM) fuel cell system for use in cogeneration applications in multi-unit residential buildings. The models describe the operation and cost of the fuel processing sub-system and the fuel cell stack sub-system. The thermodynamic model reflects the operation of the chemical reactors, heat exchangers, mixers, compressors, expanders, and stack that comprise the PEMFC system. Geometric models describe the performance of a system component based on its size (e.g., heat exchanger surface area), and, thus, relate the performance at off-design conditions to the component sizes chosen at the design condition. Economic models are based on data from the literature and address the cost of system components including the fuel processor the fuel cell materials, the stack assembly cost, the fuel cost, etc. As demonstrated in a forthcoming paper these models can be used in conjunction with optimization techniques based on decomposition to determine the optimal synthesis and design of a fuel cell system. Results obtained using the models show that a PEMFC cogeneration system is most economical for a relatively large cluster of residences (i.e. 50) and for manufacturing volumes in excess of 1500 units per year The analysis also determines the various system performance parameters including an electrical efficiency of 39% and a cogeneration efficiency of 72% at the synthesis/design point.
In this paper, a novel approach of middle-temperature solar hydrogen production using methanol steam reforming is proposed. It can be carried out at around 200-300 degrees C, much lower than the temperatures of other solar thermochemical hydrogen production. For the realization of the proposed solar hydrogen production, solar experiments are investigated in a modified 5 kW solar receiver/reactor with one-tracking parabolic trough concentrators. The feature of significantly upgrading the energy level from lower-grade solar thermal energy to higher-grade chemical energy is experimentally identified. The interaction between the hydrogen yield and the energy-level upgrade of solar thermal energy is clarified. Also, this kind of solar hydrogen production is experimentally compared with methanol decomposition. The preliminarily economic evaluation of the hydrogen production is identified. As a result, in the solar-driven steam reforming, the thermochemical efficiency of solar thermal energy converted into chemical energy reached up to 40-50% under a mean solar flux of 550-700 W/m(2), and exceeding 90% of hydrogen production is achieved, with about 70% higher than that of methanol decomposition. The thermochemical performance of solar-driven methanol steam reforming experimentally examined at around 200-300 degrees C for hydrogen production may be competitive with conventional methane reforming. The promising results obtained here indicate that the proposed solar hydrogen production may provide the possibility of a synergetic process of both high production of hydrogen and effective utilization of solar thermal energy at around 200-300 degrees C.
We report that Ca atoms severely quench the photoluminescence (PL) of an organic thin film 1,4‐bis[4‐(3,5‐di‐tert‐butylstyryl)stryyl]benzene (4PV). A submonolayer coverage (0.035 monolayer or 0.1 Å) of Ca on the 4PV surface reduced the PL of a 300 Å layer of 4PV by as much as 50%. Three distinct quenching rates were observed throughout the 200 Å Ca deposition. An exciton diffusion length of 200 Å in 4PV is estimated assuming that the PL quenching is diffusion controlled. © 1996 American Institute of Physics.
We have performed low-temperature Stark spectroscopy on a variety of different LH2 complexes from four photosynthetic bacteria, with the aim of characterizing the electric field response of the B800 and B850 absorption properties as a function of the protein environment. The following LH2 complexes were investigated: B800-850 and B800-820 of Rhodopseudomonas (Rps) acidophila; B800-850, B800-840 (αTyr+13→Phe), and B800-826 (αTyr+13→Phe, αTyr+14→Leu) of Rhodobacter (Rb.) sphaeroides; B800-850 and B800-830 (obtained at high LDAO) of Ectothiorhodospira sp.; and B800-850 of Rhodospirillum (Rsp.) molischianum. For all these cases the spectral blue shift of B850 has been assigned to the loss hydrogen-bonding interaction with the acetyl carbonyl of bacteriochlorophyll a. |Δμ| values for the 850 nm bands as well as for the blue-shifted bands are all on the order of 3−4.5 D/f. The loss of hydrogen-bonding interactions has only small effects on |Δμ| in these complexes. The values of the difference polarizability, Tr(Δα), are large (600−1400 Å3/f2). The results are discussed in terms of crystal-structure-based models for LH2, in which pigment−pigment and pigment−protein interactions are considered; strong pigment−pigment interactions were found to be especially important. The values of |Δμ| for the 800 nm band are small, 1.0−1.5 D/f for LH2 complexes from Rb. sphaeroides and Rps. acidophila. However, in Rsp. molischianum and Ectothiorhodospira sp. |Δμ| values are much larger, of the order of 3 D/f. The difference in the B800 band is assigned to the difference in orientation of the B800 pigments in Rsp. molischianum and Ectothiorhodospira sp., as compared to the Rps. acidophila and Rb. sphaeroides. Due to the difference in orientation, the interactions of the Bchl a with the surrounding protein and neighboring carotenoid pigments are also not identical.
Photosynthetic electron transport of isolated chloroplasts was usedto convert light energy to a potential difference of a galvanic cell. A current through an external circuit of the cell requires a transfer of electrons between the endogenous electron carriers and a redox mediator, and a subsequent transfer between the mediator and the electrode in each of the joined half-cells. With 2,3,5,6-tetramethyl-p-phenylenediamine or N,N,N′,N′-tetramethyl-p-phenylenediamine as mediator the second electron transfer step was found to be limiting. To increase the current through the external circuit we increased the concentration of salt and mediator as well as the surface area of the electrodes. Upon illumination the system generated a short-circuit current of up to 800 μA at a current density of 16 μA/cm2. The results are discussed with respect to the interdependence of the successive electron transfer steps and the properties of components for effective energy conversion by the cell.
The fundamental photochemical reaction of photosynthetic energy conversion, which transforms the photon energy of light in chemical free energy, takes places in a membrane-bound, pigmented reaction center protein (RC). We examine here the structure-function relationships of this uniquely efficient process. First, the RC is discussed in relation to the overall photosynthetic apparatus. Second, we highlight the X-ray diffraction analysis of two bacterial RCs, discussing the problems associated with the analysis of a non-water-soluble protein of molecular weight over 120 kDa. The structure of the polypeptide chains in the RC-protein, and the configuration of the cofactors non-covalently bound to the polypeptide scaffolding, is reviewed in detail. Third, we present a detailed account of investigations on the functioning of the RC with a number of optical and magnetic resonance spectroscopic techniques, with emphasis on the relation between structure and function. The results for RCs of purple bacteria, green bacteria and the two plant photosystems are compared, and discussed in the framework of current theories of photosynthetic electron transport.
The theoretical maxima of solar energy conversion efficiencies and productivities in oxygenic photosynthesis are evaluated. These are contrasted with actual measurements in a variety of photosynthetic organisms, including green microalgae, cyanobacteria, C4 and C3 plants. Minimizing, or truncating, the chlorophyll antenna size of the photosystems can improve photosynthetic solar energy conversion efficiency and productivity up to 3-fold. Generation of truncated light-harvesting chlorophyll antenna size (tla) strains, in all classes of photosynthetic organisms would help to alleviate excess absorption of sunlight and the ensuing wasteful dissipation of excitation energy, and to maximize solar-to-product energy conversion efficiency and photosynthetic productivity in high-density mass cultivations. The tla concept may find application in the commercial exploitation of microalgae and plants for the generation of biomass, biofuels, chemical feedstocks, as well as nutraceuticals and pharmaceuticals.
Light plays an important role in biology. In this review we discuss several processes and systems where light triggers a biological response, i.e. photosynthesis, vision, photoreceptors. For these functions Nature has chosen simple elementary chemical reactions, which occur in highly specialized and organized structures. The high efficiency and specificity of these reactions make them interesting for applications in light energy conversion and opto-electronics. In order to emphasize the synergism in studies of natural and synthetic systems we will discuss a few of each kind, with similar functions. In all cases light triggers a rapid sequence of events, which makes ultrafast spectroscopy an ideal tool to disentangle reaction mechanisms and dynamics.
Ultraviolet (UV) radiation is part of the electromagnetic spectrum. The biological effects of UV radiation vary enormously with wavelength and for this reason the UV spectrum is further subdivided into three regions: UVA, UVB, and UVC. Quantities of UV radiation are expressed using radiometric terminology. A particularly important term in clinical photobiology is the standard erythema dose (SED), which is a measure of the erythemal effectiveness of a UV exposure. UV radiation is produced either by heating a body to an incandescent temperature, as is the case with solar UV, or by passing an electric current through a gas, usually vaporized mercury. The latter process is the mechanism whereby UV radiation is produced artificially. Both the quality (spectrum) and quantity (intensity) of terrestrial UV radiation vary with factors including the elevation of the sun above the horizon and absorption and scattering by molecules in the atmosphere, notably ozone, and by clouds. For many experimental studies in photobiology it is simply not practicable to use natural sunlight and so artificial sources of UV radiation designed to simulate the UV component of sunlight are employed; these are based on either optically filtered xenon arc lamps or fluorescent lamps. The complete way to characterize an UV source is by spectroradiometry, although for most practical purposes a detector optically filtered to respond to a limited portion of the UV spectrum normally suffices.
A multi-biosensor for detection of herbicides and pollutants was constructed using various photosynthetic preparations as biosensing elements. The photosynthetic thylakoid from Spinacia oleracea L., Senecio vulgaris and its mutant resistant to atrazine were immobilized with (BSA-GA) on the surface of screen-printed sensors composed of a graphite-working electrode and Ag/AgCl reference electrode deposited on a polymeric substrate. The biosensor was composed of four flow cells with independent illumination of 650 nm to activate electron transfer in Photosystem II. The principle of the detection was based on the fact that herbicides selectively block electron transport activity in a concentration-dependent manner and that the four PSII biomediators show differential recognition activity toward herbicides. Changes of the activity were registered amperometrically as rate of photoreduction of the artificial electron acceptor DQ. The setup resulted in a reusable herbicide multibiosensor with a good stability (half-life of 16.7 h for spinach thylakoids) and limit of detection of about 10(-8) M for herbicides recovered in spring in river.
Photosynthetic proteins are a source of biological material well-suited to technological applications. They exhibit light-induced electron transfer across lipid membranes that can be exploited for the construction of photo-optical electrical devices. The structure and function of photosynthetic proteins differ across the photosynthetic evolutionary scale, allowing for their application in a range of technologies. Here we provide a general description of the basic and technical research in this sector and an overview of biochips and biosensors based on photochemical activity that have been developed for the bioassay of pollutants.
Although hydrogen is considered to be one of the most promising future energy sources and the technical aspects involved in using it have advanced considerably, the future supply of hydrogen from renewable sources is still unsolved. This review focuses on the production of hydrogen from water using biological catalysts that have been optimized by nature: the process of water-splitting photosynthesis on the one hand and hydrogen production via the catalyst hydrogenase on the other. Using water as a source of electrons and sunlight as a source of energy, both engineered natural systems and biomimetic (bio-inspired) model systems can be designed as first steps towards water-splitting-based hydrogen production (biophotolytic hydrogen production).