Tandem Modules Research Articles

Immune functions of insect βGRPs and their potential application

Insects rely completely on the innate immune system to sense the foreign bodies and to mount the immune responses. Germ-line encoded pattern recognition receptors play crucial roles in recognizing pathogen-associated molecular patterns. Among them, β-1,3-glucan recognition proteins (βGRPs) and gram-negative bacteria-binding proteins (GNBPs) belong to the same pattern recognition receptor family, which can recognize β-1,3-glucans. Typical insect βGRPs are comprised of a tandem carbohydrate-binding module in the N-terminal and a glucanase-like domain in the C-terminal. The former can recognize triple-helical β-1,3-glucans, whereas the latter, which normally lacks the enzymatic activity, can recruit adapter proteins to initiate the protease cascade. According to studies, insect βGRPs possess at least three types of functions. Firstly, some βGRPs cooperate with peptidoglycan recognition proteins to recognize the lysine-type peptidoglycans upstream of the Toll pathway. Secondly, some directly recognize fungal β-1,3-glucans to activate the Toll pathway and melanization. Thirdly, some form the ‘attack complexes’ with other immune effectors to promote the antifungal defenses. The current review will focus on the discovery of insect βGRPs, functions of some well-characterized members, structure-function studies and their potential application.

Simulated potential for enhanced performance of mechanically stacked hybrid III–V/Si tandem photovoltaic modules using DC–DC converters

This work examines a tandem module design with GaInP2 mechanically stacked on top of crystalline Si, using a detailed photovoltaic (PV) system model to simulate four-terminal (4T) unconstrained and two-terminal voltage-matched (2T VM) parallel architectures. Module-level power electronics is proposed for the 2T VM module design to enhance its performance over the breadth of temperatures experienced by a typical PV installation. Annual, hourly simulations of various scenarios indicate that this design can reduce annual energy losses to ∼0.5% relative to the 4T module configuration. Consideration is given to both performance and practical design for building or ground mount installations, emphasizing compatibility with existing standard Si modules.

Low-Cost CdTe/Silicon Tandem Solar Cells

Achieving higher photovoltaic efficiency in single-junction devices is becoming increasingly difficult, but tandem modules offer the possibility of significant efficiency improvements. Device modeling shows that four-terminal CdTe/Si tandem solar modules offer the prospect of 25%–30% module efficiency, and technoeconomic analysis predicts that these efficiency gains can be realized at costs per Watt that are competitive with CdTe and Si single junction alternatives. The cost per Watt of the modeled tandems is lower than crystalline silicon, but slightly higher than CdTe alone. However, these higher power modules reduce area-related balance of system costs, providing increased value especially in area-constrained applications. This avenue for high-efficiency photovoltaics enables improved performance on a near-term timeframe, as well as a path to further reduced levelized cost of electricity as module and cell processes continue to advance.

Cas9 Nickase-Assisted RNA Repression Enables Stable and Efficient Manipulation of Essential Metabolic Genes in Clostridium cellulolyticum.

Essential gene functions remain largely underexplored in bacteria. Clostridium cellulolyticum is a promising candidate for consolidated bioprocessing; however, its genetic manipulation to reduce the formation of less-valuable acetate is technically challenging due to the essentiality of acetate-producing genes. Here we developed a Cas9 nickase-assisted chromosome-based RNA repression to stably manipulate essential genes in C. cellulolyticum. Our plasmid-based expression of antisense RNA (asRNA) molecules targeting the phosphotransacetylase (pta) gene successfully reduced the enzymatic activity by 35% in cellobiose-grown cells, metabolically decreased the acetate titer by 15 and 52% in wildtype transformants on cellulose and xylan, respectively. To control both acetate and lactate simultaneously, we transformed the repression plasmid into lactate production-deficient mutant and found the plasmid delivery reduced acetate titer by more than 33%, concomitant with negligible lactate formation. The strains with pta gene repression generally diverted more carbon into ethanol. However, further testing on chromosomal integrants that were created by double-crossover recombination exhibited only very weak repression because DNA integration dramatically lessened gene dosage. With the design of a tandem repetitive promoter-driven asRNA module and the use of a new Cas9 nickase genome editing tool, a chromosomal integrant (LM3P) was generated in a single step and successfully enhanced RNA repression, with a 27% decrease in acetate titer on cellulose in antibiotic-free medium. These results indicate the effectiveness of tandem promoter-driven RNA repression modules in promoting gene repression in chromosomal integrants. Our combinatorial method using a Cas9 nickase genome editing tool to integrate the gene repression module demonstrates easy-to-use and high-efficiency advantages, paving the way for stably manipulating genes, even essential ones, for functional characterization and microbial engineering.

Biochemical Characterization and Substrate Degradation Mode of a Novel Exotype β-Agarase from Agarivorans gilvus WH0801.

Agarases are important hydrolytic enzymes for the biodegradation of agar. Understanding the degradation mode and hydrolysis products of agarases is essential for their utilization in oligosaccharide preparations. Herein, we cloned and expressed AgWH50B, a novel neoagarotetraose-forming β-agarase from Agarivorans gilvus WH0801 that has high specific activity and a fast reaction rate. AgWH50B consists of a C-terminal glycoside hydrolase family 50 catalytic domain with two tandem noncatalytic carbohydrate-binding modules (CBMs) in the N-terminus (residues 45-214 and 236-442). AgWH50B exhibited good enzymatic properties with high specific activity and catalytic efficiency (1523.2 U/mg and a Vmax of 1700 μmol/min/mg) under optimal hydrolysis conditions of pH 7.0 and 40 °C. Analysis of the hydrolysis products revealed that this enzyme is an exotype β-agarase and that the dominant product of agarose or oligosaccharide degradation was neoagarotetraose. These findings suggest that AgWH50B could be utilized to yield abundant neoagarotetraose.

Elucidation of the Cryptic Methyl Group Epimerase Activity of Dehydratase Domains from Modular Polyketide Synthases Using a Tandem Modules Epimerase Assay.

Dehydratase (DH) domains of cryptic function are often found in polyketide synthase (PKS) modules that produce epimerized (2S)-2-methyl-3-ketoacyl-ACP (acyl carrier protein) intermediates. A combination of tandem equilibrium isotope exchange (EIX) and a newly developed Tandem Modules Epimerase assay revealed the intrinsic epimerase activity of NanDH1 and NanDH5, from modules 1 and 5, respectively, of the nanchangmycin (1) PKS as well of NigDH1, from module 1 of the nigericin (3) PKS. Unexpectedly, all three epimerase-active DH domains were also found to possess intrinsic dehydratase activity, whereas the conventional DH domains, EryDH4, from module 4 of the erythromycin synthase, and NanDH2 from module 2 of the nanchangmycin synthase, were shown to have cryptic epimerase activity.

MicroRNA Signatures and Molecular Subtypes of Glioblastoma: The Role of Extracellular Transfer.

SummaryDespite the importance of molecular subtype classification of glioblastoma (GBM), the extent of extracellular vesicle (EV)-driven molecular and phenotypic reprogramming remains poorly understood. To reveal complex subpopulation dynamics within the heterogeneous intratumoral ecosystem, we characterized microRNA expression and secretion in phenotypically diverse subpopulations of patient-derived GBM stem-like cells (GSCs). As EVs and microRNAs convey information that rearranges the molecular landscape in a cell type-specific manner, we argue that intratumoral exchange of microRNA augments the heterogeneity of GSC that is reflected in highly heterogeneous profile of microRNA expression in GBM subtypes.

Concepts for external light trapping and its utilization in colored and image displaying photovoltaic modules

AbstractThe reflection of incident sunlight prevents photovoltaic modules from reaching their full energy conversion potential. Recently, we demonstrated significant absorption enhancement in various solar cells by external light trapping, using 3D‐printed and milled light traps. In order to facilitate direct module integration, we introduce an external light trapping design concept tackling the reflection issues at the module level. In this module design, a lens array on the module cover glass funnels the incident sunlight through small apertures in a reflective coating at the backside of the cover glass. This adapted cover glass can be applied on a conventional module design. The reflector and the solar cells together form an optical cavity, in which most reflected light is recycled by directing the reflected light back to the solar cell. A unique feature of this light trapping module is its capability to simultaneously recycle the broadband reflection from the metal front grid, the front interfaces, the reflective backside of the cell, and the white back sheet. Moreover, it allows separate integration and contacting of low and high bandgap solar cells for highly efficient hybrid tandem modules that have no current matching related losses. We show five module designs for improved light management combined with additional features such as color and image display. We discuss the optimal harvesting of the diffuse and direct component of the sunlight. The outlook of highly efficient, colored, and even image displaying modules makes this technology an interesting candidate for a new class of photovoltaic modules. Copyright © 2017 John Wiley & Sons, Ltd.

Evaluating the economic viability of CdTe/CIS and CIGS/CIS tandem photovoltaic modules

AbstractWe analyze the potential cost competitiveness of two frameless, glass–glass thin‐film tandem photovoltaic module structures, cadmium telluride (CdTe)/CuInSe2 (CIS) and CuIn0.3Ga0.7Se2 (CIGS)/CIS, based on the demonstrated cost of manufacturing the respective component cell technologies in high volume. To consider multiple economic scenarios, we base the CdTe/CIS module efficiency on the current industrial production of CdTe modules, while for CIGS/CIS, we use an aspirational estimate for CIGS efficiency. We focus on four‐terminal mechanically stacked structures, thus avoiding the need to achieve current matching between the two cells. The top cell in such a tandem must have a transparent back contact, which has not been successfully implemented to date. However, for the purpose of understanding the economic viability of both tandems, we assume that this can be implemented at a cost similar to that of sputtered indium tin oxide. The cost of both tandem module structures was found to be nearly identical on an equal‐area basis and approximately $30/m2 higher than the single‐junction alternatives. Both tandem modules are about 4% (absolute) more efficient than a module by using the top‐cell material alone. We find that these tandem modules might reduce total system cost by as much as 11% in applications having a high area‐related balance‐of‐system cost, such as area‐constrained residential systems; however, the relative advantage of tandems decreases in the cases where balance‐of‐system costs are lower, such as in commercial and utility scale systems. Copyright © 2017 John Wiley & Sons, Ltd.

Economic competitiveness of III–V on silicon tandem one‐sun photovoltaic solar modules in favorable future scenarios

AbstractTandem modules combining a III–V top cell with a Si bottom cell offer the potential to increase the solar energy conversion efficiency of one‐sun photovoltaic modules beyond 25%, while fully utilizing the global investment that has been made in Si photovoltaics manufacturing. At present, the cost of III–V cells is far too high for this approach to be competitive for one‐sun terrestrial power applications. We investigated the system‐level economic benefits of both GaAs/Si and InGaP/Si tandem modules in favorable future scenarios where the cost of III–V cells is substantially reduced, perhaps to less than the cost of Si cells. We found, somewhat unexpectedly, that these tandems can reduce installed system cost only when the area‐related balance‐of‐system cost is high, such as for area‐constrained residential rooftop systems in the USA. When area‐related balance‐of‐system cost is lower, such as for utility‐scale systems, the tandem module offers no benefit. This is because a system using tandem modules is more expensive than one using single‐junction Si modules when III–V cells are expensive, and a system using tandem modules is more expensive than one using single‐junction III–V modules when III–V cells are inexpensive. Copyright © 2016 John Wiley & Sons, Ltd.

Life Cycle Assessment and eco-efficiency of prospective, flexible, tandem organic photovoltaic module

Organic photovoltaic technology has reached a sufficient maturity to enable commercially viable products for integration into buildings with power conversion efficiencies up to about 5%, for example, using a roll-to-roll (R2R) processing of single bulk heterojunction devices technology. This paper reports on a Life Cycle Assessment (LCA) and eco-efficiency analysis of prospective tandem organic photovoltaic (OPV) modules which have been manufactured to the most part in pilot environments. To realistically model the LCA and eco-efficiency a power conversion efficiency of both 10% and a more modest 8% were used with lifespan scenarios of 15 and 20years. The tandem OPV modules modelled in this study have: a cell stack consisting of new advanced materials such as nano-sized zinc oxide, nano-sized silver, and semiconductor polymers; a light management structure; and new flexible PET based encapsulation with organic and inorganic barriers. This tandem technology was modelled assuming an industrialized production based on real and estimated resource consumption and pollution data from an existing roll-to-roll pilot OPV plant and from material suppliers together with projected costs. Established multi-silicon (multi-Si) and cadmium-telluride (CdTe) photovoltaics were taken to benchmark the environmental impacts in production and the expected levelized costs of electricity. The results of the modelling show that the production of 1m2 tandem OPV module represents only approximately 3–10% of the impacts of 1 m2 of the benchmark multi-Si or CdTe modules when the global warming potential (GWP), cumulative energy demand (CED), eco-toxicity, and metal depletion environmental impacts are considered. The results also show the energy payback time of a tandem OPV at facade is only 18–55% of that of the benchmarks, and the GWP is just 12–60% of that of the benchmarks. An eco-efficiency comparison indicates that, for applications where photovoltaic modules cannot be optimally oriented towards the sun, a flexible tandem OPV might be a superior alternative to multi-Si and CdTe modules.

Heterologous expression of family 10 xylanases from Acidothermus cellulolyticus enhances the exoproteome of Caldicellulosiruptor bescii and growth on xylan substrates.

BackgroundThe ability to deconstruct plant biomass without conventional pretreatment has made members of the genus Caldicellulosiruptor the target of investigation for the consolidated processing of lignocellulosic biomass to biofuels and bioproducts. These Gram-positive bacteria are hyperthermophilic anaerobes and the most thermophilic cellulolytic organisms so far described. They use both C5 and C6 sugars simultaneously and have the ability to grow well on xylan, a major component of plant cell walls. This is an important advantage for their use to efficiently convert biomass at yields sufficient for an industrial process. For commodity chemicals, yield from substrate is perhaps the most important economic factor. In an attempt to improve even further the ability of C. bescii to use xylan, we introduced two xylanases from Acidothermus cellulolyticus. Acel_0180 includes tandem carbohydrate-binding modules (CBM2 and CBM3) located at the C-terminus, one of which, CBM2, is not present in C. bescii. Also, the sequences of Xyn10A and Acel_0180 have very little homology with the GH10 domains present in C. bescii. For these reasons, we selected these xylanases as potential candidates for synergistic interaction with those in the C. bescii exoproteome.ResultsHeterologous expression of two xylanases from Acidothermus cellulolyticus in Caldicellulosiruptor bescii resulted in a modest, but significant increase in the activity of the exoproteome of C. bescii on xylan substrates. Even though the increase in extracellular activity was modest, the ability of C. bescii to grow on these substrates was dramatically improved suggesting that the xylan substrate/microbe interaction substantially increased deconstruction over the secreted free enzymes alone.ConclusionsWe anticipate that the ability to efficiently use xylan, a major component of plant cell walls for conversion of plant biomass to products of interest, will allow the conversion of renewable, sustainable, and inexpensive plant feedstocks to products at high yields.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0588-9) contains supplementary material, which is available to authorized users.

Combination of Advanced Optical Modelling with Electrical Simulation for Performance Evaluation of Practical 4-terminal Perovskite/c-Si Tandem Modules

The perovskite solar cell is considered a promising candidate as the top cell for high-efficiency tandem devices with crystalline silicon (c-Si) bottom cells, contributing to the cost reduction of photovoltaic energy. In this contribution, a simulation method, involving optical and electrical modelling, is established to calculate the performance of 4-terminal (4T) perovskite/c-Si tandem devices on a mini-module level. Optical and electrical characterization of perovskite and c-Si solar cells are carried out to verify the simulation parameters. With our method, the influence of transparent conductive oxide (TCO) layer thickness of perovskite top cells on the performance of tandem mini-modules is investigated in case of both tin-doped indium oxide (ITO) and hydrogen-doped indium oxide (IO:H). The investigation shows that optimization of TCO layer thickness and replacement of conventional ITO with highly transparent IO:H can lead to an absolute efficiency increase of about 1%. Finally, a practical assessment of the efficiency potential for the 4T perovskite/c-Si tandem mini-module is carried out, indicating that with a relatively simple 4T tandem module structure the efficiency of a single-junction c-Si mini-module (19.3%) can be improved by absolute 4.5%.

Microcrystalline bottom cells in large area thin film silicon MICROMORPH™ solar modules

The influence of working pressure and inter-electrode gap distance on the quality of microcrystalline silicon prepared by PECVD at 40MHz in three different KAI™ reactors designs with inter-electrode gaps of 28mm, 16mm and 7mm has been investigated. The microcrystalline devices were implemented and studied as bottom cells in MICROMORPH™ tandem modules or processed with an optical filter to simulate the absorption of a top cell on a module size of 1.43m2. Increasing the working pressure from 250Pa to 2000Pa resulted in an improvement of the efficiency of 1% absolute due to improvement in the open circuit voltage Voc and the fill factor FF. The influence of the deposition rate on the quality of the intrinsic absorber layers has been investigated and optimized. An unconventional crystallinity profile throughout the intrinsic absorber layer has been developed to further improve either the current density Jsc or Voc and FF. By controlling and tuning the Raman crystallinity a very high open circuit voltage Voc of >1.42V in a tandem cell design in full size modules (1.43m2) could be realized.

Thin-film silicon tandem (MICROMORPH™) module design and key reliability topics

Thin-film silicon tandem (MICROMORPH™) module design optimization process for performance maximization is described together with an analysis of some key reliability topics.In the first part, the procedure for module layout optimization to achieve the maximum module power output is described. In monolithic thin-film modules the layout is realized through a laser scribing interconnection process: a well-controlled laser scribing process is therefore essential to ensure optimal module performance and to minimize unwanted losses.The second part of the paper focuses on some of the materials used in the fabrication of a solar cell and module of such technology and the processes used to achieve such module assembly, as well as a description of some of the possible failure modes. Special attention is paid to the zinc oxide transparent conductive oxide (ZnO TCO) layers used for the front and back contacts.The bottom cell (BoCe) and its stability is also analyzed in detail: the influence of process parameters on the BoCe degradation behavior including the differences observed using different thin-film silicon (TF-Si) deposition reactor types, different lamination foils and the impact using different front contact haze is discussed.In the final part of the paper the effect of particle contamination on the module performance is reviewed: specifically contamination by particles generated during deposition and handling processes. Finally relevant countermeasures to prevent additional module performance loss are discussed.

Insomnia Characterization: From Hypnogram to Graph Spectral Theory.

To quantify and differentiate control and insomnia sleep onset patterns through biomedical signal processing of overnight polysomnograms. The approach consisted of three tandem modules: 1) biosignal processing module, which used state-space time-varying autoregressive moving average (TVARMA) processes with recursive particle filter, 2) hypnogram generation module that implemented a fuzzy inference system (FIS), and 3) insomnia characterization module that discriminated between control and subjects with insomnia using a logistic regression model trained with a set of similarity measures ( d1, d2 , d3, d4). The study employed sleep onset periods from 16 control and 16 subjects with insomnia. State-spaced TVARMA processes with recursive particle filtering provided resilience to nonlinear, nonstationary, and non-Gaussian conditions of biosignals. FIS managed automated sleep scoring robust to intersubjects' and interraters' variability. The similarity distances quantified in a scalar measure the transitions amongst sleep onset stages, computed from expert and automated hypnograms. A statistical set of unpaired two-tailed t -tests suggested that distances d1 , d2, and d3 had larger statistical significance ( ) to characterize sleeping patterns. The logistic regression model classified control and subjects with insomnia with sensitivity 87 % , specificity 75 %, and accuracy 81 %. Our approach can perform a supportive role in either biosignal processing, sleep staging, insomnia characterization, or all the previous, coping with time-consuming procedures and massive data volumes of standard protocols. The introduction of graph spectral theory and logistic regression for the diagnosis of insomnia represents a novel concept, attempting to describe complex sleep dynamics throughout transitions networks and scalar measures.

Efficient polymer tandem modules and solar cells by doctor blading

Doctor bladed polymer tandem modules are realised without loss in Voc by an efficient monolithical interconnection of the subcells.

Structural Basis of ATP Hydrolysis and Intersubunit Signaling in the AAA+ ATPase p97

p97 belongs to the superfamily of AAA+ ATPases and is characterized by a tandem AAA module, an N-terminal domain involved in substrate and cofactor interactions, and a functionally important unstructured C-terminal tail. The ATPase activity is controlled by an intradomain communication within the same protomer and an interdomain communication between neighboring protomers. Here, we present for the first time crystal structures in which the physiologically relevant p97 hexamer constitutes the content of the asymmetric unit, namely in the apo state without nucleotide in either the D1 or D2 module and in the pre-activated state with ATPγS bound to both modules. The structures provide new mechanistic insights into the interdomain communication mediated by conformational changes of the C terminus as well as an intersubunit signaling network, which couples the nucleotide state to the conformation of the central putative substrate binding pore.

Design and long-term monitoring of DSC/CIGS tandem solar module

This paper describes the design and development of tandem dye-sensitized/Cu(In, Ga)Se (DSC/CIGS) PV modules. The tandem PV module comprised of the top DSC module and a bottom commercial 0,8 m2 CIGS module. The top DSC module was made of 10 DSC mini-modules with the field size of 20 × 20 cm2 each. Tandem DSC/CIGS PV modules were used for providing the long-term monitoring of energy yield and electrical parameters in comparison with standalone CIGS modules under outdoor conditions. The outdoor test facility, containing solar modules of both types and a measurement unit, was located on the roof of the Institute of Biochemical Physics in Moscow. The data obtained during monitoring within the 2014 year period has shown the advantages of the designed tandem DSC/CIGS PV-modules over the conventional CIGS modules, especially for cloudy weather and low-intensity irradiation conditions.

Improved conversion efficiencies of thin-film silicon tandem (MICROMORPH™) photovoltaic modules

Increased electrical power generated from a thin-film silicon (TF-Si) photovoltaic device can lead to a reduced cost of electricity production that will support the mass adoption of this technology as a renewable energy source. Extracting the highest conversion efficiency from ‘champion’ large area TF-Si modules has been the focus of development at TEL Solar AG, Trübbach. The layer deposition process adjustments and further module technology improvements that led to a significant increase in the absolute stabilized module conversion efficiency of large area (1.43m2) tandem MICROMORPH™ modules centered first on obtaining high quality amorphous TF-Si deposited materials for the top cell. This was integrated with microcrystalline TF-Si material for the bottom cell that was deposited under conditions close to the transition point between the amorphous and microcrystalline growth regimes. In an optimized solar cell design the TF-Si materials were then combined with effective light management technologies and an improved module layout. The end result of a world record large area (1.43m2) stabilized module conversion efficiency of 12.34% was certified by the European Solar Test Installation (ESTI). The main technology contributions in the device design for this breakthrough result that generated more than 13.2% stabilized efficiency from each equivalent 1cm2 of the active area of the full module are described.