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Light-powered cell factories Bacteria and fungi are used industrially to produce commodity fine chemicals at vast scale. Sugars are an economical feedstock, but many of the desired products require enzymatic reduction, meaning that some of the sugar must be diverted to regenerate the cellular reductant NADPH (reduced form of nicotinamide adenine dinucleotide phosphate). Guo et al. show that electrons from light-sensitive nanoparticles can drive reduction of cellular NADPH in yeast, which can then be used for reductive biosynthetic reactions. This system can reduce diversion of carbon to NADPH regeneration and should be compatible with many existing engineered strains of yeast. Science , this issue p. 813

The demand for renewable and sustainable fuel has prompted the rapid development of advanced nanotechnologies to effectively harness solar power. The construction of photosynthetic biohybrid systems (PBSs) aims to link preassembled biosynthetic pathways with inorganic light absorbers. This strategy inherits both the high light-harvesting efficiency of solid-state semiconductors and the superior catalytic performance of whole-cell microorganisms. Here, we introduce an intracellular, biocompatible light absorber, in the form of gold nanoclusters (AuNCs), to circumvent the sluggish kinetics of electron transfer for existing PBSs. Translocation of these AuNCs into non-photosynthetic bacteria enables photosynthesis of acetic acid from CO2. The AuNCs also serve as inhibitors of reactive oxygen species (ROS) to maintain high bacterium viability. With the dual advantages of light absorption and biocompatibility, this new generation of PBS can efficiently harvest sunlight and transfer photogenerated electrons to cellular metabolism, realizing CO2 fixation continuously over several days.

As NASA and other space agencies across the world prepare their astronauts to withstand the hazards of space travel and habitation on Mars, tinier adventurers have begun to receive a similar outfitting. For humans to live in extreme environments such as the darkest, coldest, radiation bombarded reaches of space, we must equip useful microorganisms to thrive and survive under similar conditions. This insight has expanded microbial sciences to the materials sciences: blending soft, squishy cells with hard, rocky crystals. And just as billionaire-playboy-philanthropist Tony Stark donned an array of gadgetry to become Iron Man, so too must bacteria and yeast receive the cyborg treatment to augment their functionality for the future of biotechnology.

We demonstrate the synthesis of NH3 from N2 and H2O at ambient conditions in a single reactor by coupling hydrogen generation from catalytic water splitting to a H2-oxidizing bacterium Xanthobacter autotrophicus, which performs N2 and CO2 reduction to solid biomass. Living cells of X. autotrophicus may be directly applied as a biofertilizer to improve growth of radishes, a model crop plant, by up to ∼1,440% in terms of storage root mass. The NH3 generated from nitrogenase (N2ase) in X. autotrophicus can be diverted from biomass formation to an extracellular ammonia production with the addition of a glutamate synthetase inhibitor. The N2 reduction reaction proceeds at a low driving force with a turnover number of 9 × 109 cell–1 and turnover frequency of 1.9 × 104 s–1⋅cell–1 without the use of sacrificial chemical reagents or carbon feedstocks other than CO2. This approach can be powered by renewable electricity, enabling the sustainable and selective production of ammonia and biofertilizers in a distributed manner.

Photosynthetic biohybrid systems (PBSs) combine the strengths of inorganic materials and biological catalysts by exploiting semiconductor broadband light absorption to capture solar energy and subsequently transform it into valuable CO2-derived chemicals by taking advantage of the metabolic pathways in living organisms. In this work, we first traverse through a brief history of recent PBSs, demonstrating the modularity and diversity of possible architectures to rival and, in many cases, surpass the performance of chemistry or biology alone before envisioning the future of these hybrid systems, opportunities for improvement, and its role in sustainable living here on earth and beyond.

Tandem "Z-scheme" approaches to solar-to-chemical production afford the ability to independently develop and optimize reductive photocatalysts for CO2 reduction to multicarbon compounds and oxidative photocatalysts for O2 evolution. To connect the two redox processes, molecular redox shuttles, reminiscent of biological electron transfer, offer an additional level of facile chemical tunability that eliminates the need for solid-state semiconductor junction engineering. In this work, we report a tandem inorganic-biological hybrid system capable of oxygenic photosynthesis of acetic acid from CO2. The photoreductive catalyst consists of the bacterium Moorella thermoacetica self-photosensitized with CdS nanoparticles at the expense of the thiol amino acid cysteine (Cys) oxidation to the disulfide form cystine (CySS). To regenerate the CySS/Cys redox shuttle, the photooxidative catalyst, TiO2 loaded with cocatalyst Mn(II) phthalocyanine (MnPc), couples water oxidation to CySS reduction. The combined system M. thermoacetica-CdS + TiO2-MnPc demonstrates a potential biomimetic approach to complete oxygenic solar-to-chemical production.

Semi-artificial photosynthetic systems aim to overcome the limitations of natural and artificial photosynthesis while providing an opportunity to investigate their respective functionality. The progress and studies of these hybrid systems is the focus of this forward-looking perspective. In this Review, we discuss how enzymes have been interfaced with synthetic materials and employed for semi-artificial fuel production. In parallel, we examine how more complex living cellular systems can be recruited for in vivo fuel and chemical production in an approach where inorganic nanostructures are hybridized with photosynthetic and non-photosynthetic microorganisms. Side-by-side comparisons reveal strengths and limitations of enzyme- and microorganism-based hybrid systems, and how lessons extracted from studying enzyme hybrids can be applied to investigations of microorganism-hybrid devices. We conclude by putting semi-artificial photosynthesis in the context of its own ambitions and discuss how it can help address the grand challenges facing artificial systems for the efficient generation of solar fuels and chemicals.

Direct solar-powered production of value-added chemicals from CO2 and H2O, a process that mimics natural photosynthesis, is of fundamental and practical interest. In natural photosynthesis, CO2 is first reduced to common biochemical building blocks using solar energy, which are subsequently used for the synthesis of the complex mixture of molecular products that form biomass. Here we report an artificial photosynthetic scheme that functions via a similar two-step process by developing a biocompatible light-capturing nanowire array that enables a direct interface with microbial systems. As a proof of principle, we demonstrate that a hybrid semiconductor nanowire-bacteria system can reduce CO2 at neutral pH to a wide array of chemical targets, such as fuels, polymers, and complex pharmaceutical precursors, using only solar energy input. The high surface-area silicon nanowire array harvests light energy to provide reducing equivalents to the anaerobic bacterium, Sporomusa ovata, for the photoelectrochemical production of acetic acid under aerobic conditions (21% O2) with low overpotential (η < 200 mV), high Faradic efficiency (up to 90%), and long-term stability (up to 200 hours). The resulting acetate (~ 6 g/L) can be activated to acetyl coenzyme A (acetyl-CoA) by genetically engineered Escherichia coli and used as a building block for a variety of value-added chemicals, such as n-butanol, polyhydroxybutyrate (PHB) polymer, and three different isoprenoid natural products. As such, interfacing biocompatible solid-state nanodevices with living systems provides a starting point for developing a programmable system of chemical synthesis entirely powered by sunlight.

Future solar-to-chemical production will rely upon a deep understanding of the material–microorganism interface. Hybrid technologies, which combine inorganic semiconductor light harvesters with biological catalysis to transform light, air, and water into chemicals, already demonstrate a wide product scope and energy efficiencies surpassing that of natural photosynthesis. But optimization to economic competitiveness and fundamental curiosity beg for answers to two basic questions: (1) how do materials transfer energy and charge to microorganisms, and (2) how do we design for bio- and chemocompatibility between these seemingly unnatural partners? This Perspective highlights the state-of-the-art and outlines future research paths to inform the cadre of spectroscopists, electrochemists, bioinorganic chemists, material scientists, and biologists who will ultimately solve these mysteries.

Angesichts der Unvereinbarkeit eines zunehmenden Verbrauchs von Kraftstoffen und chemischen Produkten und einer nur endlichen Menge an Ressourcen versuchen wir Moglichkeiten zu finden, wie wir unsere Gesellschaft auf Dauer nachhaltig gestalten konnen. Die kunstliche Photosynthese nutzt das Sonnenlicht, um reichlich vorhandene Ressourcen in hochwertige Chemikalien umzuwandeln. Deshalb gilt sie als die aussichtsreichste Methode. Hier werden Entwicklungen und neueste Fortschritte sowie noch bestehende Herausforderungen fur ihre Schlusselprozesse, die photoelektrochemische Wasserspaltung und die elektrochemische CO2-Reduktion, beschrieben. Ein Uberblick uber die Fortschritte in der Katalyse, um den erneuerbaren Wasserstoff als Grundstoff fur die Produktion von Chemikalien einzusetzen, soll verdeutlichen, welche Rolle die kunstliche Photosynthese in einer nachhaltigen Chemie spielen wird.

An expanding renewable energy market to supplant petrochemicals has motivated synthesis technologies that use renewable feedstocks, such as CO2. Hybrid biological-inorganic systems provide a sustainable, efficient, versatile, and inexpensive chemical synthesis platform. These systems comprise biocompatible electrodes that transduce electrical energy either directly or indirectly into bioavailable energy, such as H2 and NAD(P)H. In combination, specific bacteria use these energetic reducing equivalents to fix CO2 into multi-carbon organic compounds. As hybrid biological-inorganic technologies have developed, the focus has shifted from phenomenological and proof-of-concept discovery towards enhanced energy efficiency, production rate, product scope, and industrial robustness. In this review, we highlight the progress and the state-of-the-art of this field and describe the advantages and challenges involved in designing bio- and chemo- compatible systems.

Studying bacteria-nanostructure interactions is crucial to gaining controllable interfacing of biotic and abiotic components in advanced biotechnologies. For bioelectrochemical systems, tunable cell-electrode architectures offer a path toward improving performance and discovering emergent properties. As such, Sporomusa ovata cells cultured on vertical silicon nanowire arrays formed filamentous cells and aligned parallel to the nanowires when grown in increasing ionic concentrations. Here, we propose a model describing the kinetic and the thermodynamic driving forces of bacteria-nanowire interactions.

© 2016, National Academy of Sciences. All rights reserved. The rise of inorganic-biological hybrid organisms for solar-to-chemical production has spurred mechanistic investigations into the dynamics of the biotic-abiotic interface to drive the development of next-generation systems. The model system, Moorella thermoacetica-cadmium sulfide (CdS), combines an inorganic semiconductor nanoparticle light harvester with an acetogenic bacterium to drive the photosynthetic reduction of CO2to acetic acid with high efficiency. In this work, we report insights into this unique electrotrophic behavior and propose a charge-transfer mechanism from CdS to M. thermoacetica. Transient absorption (TA) spectroscopy revealed that photoexcited electron transfer rates increase with increasing hydrogenase (H2ase) enzyme activity. On the same time scale as the TA spectroscopy, time-resolved infrared (TRIR) spectroscopy showed spectral changes in the 1,700-1,900-cm-1spectral region. The quantum efficiency of this system for photosynthetic acetic acid generation also increased with increasing H2ase activity and shorter carrier lifetimes when averaged over the first 24 h of photosynthesis. However, within the initial 3 h of photosynthesis, the rate followed an opposite trend: The bacteria with the lowest H2ase activity photosynthesized acetic acid the fastest. These results suggest a two-pathway mechanism: a high quantum efficiency charge-transfer pathway to H2ase generating H2as a molecular intermediate that dominates at long time scales (24 h), and a direct energy-transducing enzymatic pathway responsible for acetic acid production at short time scales (3 h). This work represents a promising platform to utilize conventional spectroscopic methodology to extract insights from more complex biotic-abiotic hybrid systems.

We report on the correlation between the flux, color and polarization variations on time scales of days--months in blazars, and discuss their universal aspects. We performed monitoring of 42 blazars in the optical and near-infrared bands from 2008 to 2010 using TRISPEC attached to the "Kanata" 1.5-m telescope. We found that 28 blazars exhibited "bluer-when-brighter" trends in their whole or a part of time-series data sets. This corresponds to 88% of objects that were observed for >10 days. Thus, our observation unambiguously confirmed that the "bluer-when-brighter" trend is common in the emission from blazar jets. This trend was apparently generated by a variation component with a constant and relatively blue color and an underlying red component. Prominent short-term flares on time scales of days--weeks tended to exhibit a spectral hysteresis; their rising phases were bluer than their decay phases around the flare maxima. In contrast to the strong flux--color correlation, the correlation of the flux and polarization degree was relatively weak; only 10 objects showed significant positive correlations. Rotations of polarization were detected only in three objects: PKS 1510-089, 3C 454.3, and PKS 1749+096, and possibly in S5 0716+714. We also investigated the dependence of the degree of variability on the luminosity and the synchrotron peak frequency, ��_peak. As a result, we found that lower luminosity and higher ��_peak objects had smaller variations in their amplitudes both in the flux, color, and polarization degree. Our observation suggests the presence of several distinct emitting sources, which have different variation time-scales, colors, and polarizations. We propose that the energy injection by, for example, internal shocks in relativistic shells is a major factor for blazar variations on time scales of both days and months., 39 pages, accepted for publication in PASJ

Using light in the darkness Solid-state devices can efficiently capture solar energy to produce chemicals and fuels from carbon dioxide. Yet biology has already developed a high-specificity, low-cost system to do just that through photosynthesis. Sakimoto et al. developed a biological-inorganic hybrid that combines the best of both worlds (see the Perspective by Müller). They precipitated semiconductor nanoparticles on the surface of a nonphotosynthetic bacterium to serve as a light harvester. The captured energy sustained cellular metabolism, producing acetic acid: a natural waste product of respiration. Science , this issue p. 74 ; see also p. 34

The apparent incongruity between the increasing consumption of fuels and chemicals and the finite amount of resources has led us to seek means to maintain the sustainability of our society. Artificial photosynthesis, which utilizes sunlight to create high-value chemicals from abundant resources, is considered as the most promising and viable method. This Minireview describes the progress and challenges in the field of artificial photosynthesis in terms of its key components: developments in photoelectrochemical water splitting and recent progress in electrochemical CO2 reduction. Advances in catalysis, concerning the use of renewable hydrogen as a feedstock for major chemical production, are outlined to shed light on the ultimate role of artificial photosynthesis in achieving sustainable chemistry.

The apparent incongruity between the increasing consumption of fuels and chemicals and the finite amount of resources has led us to seek means to maintain the sustainability of our society. Artificial photosynthesis, which utilizes sunlight to create high-value chemicals from abundant resources, is considered as the most promising and viable method. This Minireview describes the progress and challenges in the field of artificial photosynthesis in terms of its key components: developments in photoelectrochemical water splitting and recent progress in electrochemical CO2 reduction. Advances in catalysis, concerning the use of renewable hydrogen as a feedstock for major chemical production, are outlined to shed light on the ultimate role of artificial photosynthesis in achieving sustainable chemistry.

We have developed an optical and near-infrared instrument HONIR (Hiroshima Optical and Near-InfraRed camera) with imaging, spectroscopy, and polarimetry capabilities in two (one optical and one near-infrared) bands simultaneously. Imaging capability with a field of view of 10 arcmin by 10 arcmin has been available since 2011, as reported in the previous SPIE conference. In addition, spectroscopic and polarimetric optical components (grisms, an Wollaston prism, a half-wave plate, and focal masks) were installed in the instrument, which enabled us to perform spectroscopy and linear polarization measurement by imaging polarimetry and spectro-polarimetry. Spectral resolution of R = λ/(triangle)λ ~ 440 - 800 is achieved in spectroscopy using a slit mask with an 1".3 width. In polarimetry, instrumental polarization is less than ~0.05 % with stability of better than ~0.05 %, which is sufficiently small to achieve an aimed accuracy of polarization measurement of ~0.1 % at primal observing wavelengths.

There is considerable interest in the controlled p-type and n-type doping of carbon nanotubes (CNT) for use in a range of important electronics applications, including the development of hybrid CNT/silicon (Si) photovoltaic devices. Here, we demonstrate that easy to handle metallocenes and related complexes can be used to both p-type and n-type dope single-walled carbon nanotube (SWNT) thin films, using a simple spin coating process. We report n-SWNT/p-Si photovoltaic devices that are >450 times more efficient than the best solar cells of this type currently reported and show that the performance of both our n-SWNT/p-Si and p-SWNT/n-Si devices is related to the doping level of the SWNT. Furthermore, we establish that the electronic structure of the metallocene or related molecule can be correlated to the doping level of the SWNT, which may provide the foundation for controlled doping of SWNT thin films in the future.

We have developed an optical-infrared instrument HONIR (Hiroshima Optical and Near-InfraRed camera) to be attached to the 1.5-m Kanata telescope at Higashi-Hiroshima Observatory, Hiroshima University. HONIR is a three color (one optical and two near-infrared bands among 0.5–2.4 µm) simultaneous imager and spectrograph with a polarimetry function. The field of view of the imaging mode is 10 arcmin square with a spatial sampling of 0".29. Among the planned multipurpose functions, a two color (0.5–1.0 µm and 1.15–2.40 µm) simultaneous imaging function has been installed and operated so far. The remaining functions, spectroscopy and polarimetry, and the second near-infrared band arm, are under development and will be installed in the near future.

著者人数: 93名, Accepted: 2012-05-30, 資料番号: SA1004165000

We have developed an optical wide‐field polarimeter, HOWPol, which employs a wedged double Wollaston prism and enables us to derive linear polarization (i.e., Stokes Q/I and U/I) from only a single exposure. We successfully performed observation for the afterglow of GRB 091208B. Its first exposure started ∼150 seconds after the gamma‐ray trigger. Our preliminary result suggests that the early afterglow was significantly polarized, larger than a few percent.

The effects of overlapping resonances in dielectronic recombination (or in photoionization) of a highly-charged ion are investigated. The example taken in this report is the coupling between 2s3s and 2p3p resonance states of an helium-like ion. The energy separation of the 2s3s and the 2p3p resonance states is always larger than the autoionizing widths for all ions. However, the energy separation becomes smaller than the radiative decay widths for a highly-charged ion. This report discusses the case that resonances become overlapping owing to the radiative decay effect. An isolated-resonance approximation usually employed in the calculation of dielectronic recombination processes is also examined.

The gamma-ray-detected blazar 3C 454.3 exhibits dramatic flux and polarization variations in the optical and near-infrared bands. In December 2010, the object emitted a very bright outburst. We monitored it for approximately four years (including the 2010 outburst) by optical and near-infrared photopolarimetry. During the 2010 outburst, the object emitted two rapid, redder brightenings, at which the polarization degrees (PDs) in both bands increased significantly and the bands exhibited a frequency-dependent polarization. The observed frequency-dependent polarization leads us to propose that the polarization vector is composed of two vectors. Therefore, we separate the observed polarization vectors into short and long-term components that we attribute to the emissions of the rapid brightenings and the outburst that varied the timescale of days and months, respectively. The estimated PD of the short-term component is greater than the maximum observed PD and is close to the theoretical maximum PD. We constrain the bulk Lorentz factors and inclination angles between the jet axis and the line of sight from the estimated PDs. In this case, the inclination angle of the emitting region of short-term component from the first rapid brightening should be equal to 90$^{\circ}$, because the estimated PD of the short-term component was approximately equal to the theoretical maximum PD. Thus, the Doppler factor at the emitting region of the first rapid brightening should be equal to the bulk Lorentz factor., 8 pages, 6 figures, accepted for publication in ApJ

We report on the results of optical–near-infrared photopolarimetric observations of BL Lac conducted from 2008 to 2011. Our observations are consistent with past studies in which the behavior of the polarization of BL Lac could be understood with two components: short flares whose polarization angles randomly change, and a longlived component. In addition, we detected a gradually decreasing trend in the total flux, the polarized flux, and the polarization degree without a large variation in the polarization angle from 2008 to mid-2009. These results suggest that the long-lived component decayed from 2008 to mid-2009. We propose that the long-lived component is not stationary, but is probably variable with a time-scale of years. We found no change in the activity of the short flares in 2008 and 2009, when the long-lived component was strong and weak, respectively. Furthermore, there were no clear differences in the mean color and the distribution of the polarization angle of the short flares from 2008 to 2009. These facts indicate that the emitting region of the long-term component was physically disconnected to that of the short flares. The color of the long-term component was bluer than that of the short flares, indicating a higher synchrotron peak-frequency. This could be due to a low efficiency of synchrotron and/or Compton cooling in the emitting region of the long-lived component. The long-term component is possibly originated from a relatively downstream region in the jet where the electron density is low, or the external radiation field is weak.

Smooth and aligned single walled carbon nanotube (SWNT) thin films with improved optoelectronic performance are fabricated using a superacid slide casting method. Deposition of as made SWNT thin film on silicon (Si) together with post treatments result in SWNT/Si hybrid solar cells with unprecedented high fill factor of 73.8%, low ideality factor of 1.08 as well as overall dry cell power conversion efficiency of 11.5%.

Peak E substance, a trace impurity in l -tryptophan, has been associated epidemiologically with an outbreak of eosinophilia-myalgia syndrome (EMS) in the USA in 1989. After fractionation and purification of this substance, nuclear magnetic resonance and fast-atom-bombardment mass spectroscopy were used to identify the molecular structures of peak X/X′ (formed by the decomposition of peak E substance in a simulated gastric fluid) and peak Y/Y′ substances (which are believed to be the intermediates in the transformation of peak E substance to peak X/X′ substances). The analyses were also performed on synthesized peak E substance obtained from the reaction of tryptophan with acetaldehyde. The results indicated that the synthesized substance was of high purity and was suitable for use in studies investigating the relationship between peak E substance and EMS onset.

A perturbative treatment in the adiabatic representation, which considers the Coriolis transition, and connects to the impact parameter Born theory at large impact parameters, is formulated and applied to the rotational excitation of the HDO molecule by ion collisions. By this method, the collision dynamics at large impact parameters are described much better than by the impact parameter Born theory. At very low energies, however, the collision dynamics are better described by neglecting the Coriolic transition.

3C 66A is an intermediate-frequency-peaked BL Lac object detected by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope. We present a study of the long-term variations of this blazar seen over 2 years at GeV energies with Fermi and in the optical (flux and polarization) and near infrared with the Kanata telescope. In 2008, the first year of the study, we find a correlation between the gamma-ray flux and the measurements taken with the Kanata telescope. This is in contrast to the later measurements performed during 2009--2010 which show only a weak correlation along with a gradual increase of the optical flux. We calculate an external seed photon energy density assuming that the gamma-ray emission is due to external Compton scattering. The energy density of the external photons is found to be higher by a factor of two in 2008 compared to 2009--2010. We conclude that the different behaviors observed between the first year and the later years might be explained by postulating two different emission components., Comment: 9 pages, 10 figures

We present detailed, long term near-infrared (NIR) light curves of GRS 1915+105 obtained in 2007–2008, covering its long “soft state” for the first time. From our NIR monitoring and X-ray data of the All Sky Monitor onboard Rossi X-ray Timing Explorer, we discovered that the NIR flux dropped by > 1 mag during short X-ray flares with a time-scale of days. Upon termination of the soft state, the H Ks color reddened and the anti-correlation pattern was broken. The observed H Ks color variation suggests that the dominant NIR source was an accretion disk during the soft state. The short X-ray flares during the soft state were associated with spectral hardening in X-rays and increasing radio emission, indicating jet ejection. The temporal NIR fading during the X-ray flares thus implies a sudden decrease in the contribution of the accretion disk when a jet is ejected.