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"Tanaka, A"
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A megacomplex composed of both photosystem reaction centres in higher plants
Throughout the history of oxygen evolution, two types of photosystem reaction centres (PSI and PSII) have worked in a coordinated manner. The oxygen evolving centre is an integral part of PSII, and extracts an electron from water. PSI accepts the electron, and accumulates reducing power. Traditionally, PSI and PSII are thought to be spatially dispersed. Here, we show that about half of PSIIs are physically connected to PSIs in
Arabidopsis thaliana
. In the PSI–PSII complex, excitation energy is transferred efficiently between the two closely interacting reaction centres. PSII diverts excitation energy to PSI when PSII becomes closed-state in the PSI–PSII complex. The formation of PSI–PSII complexes is regulated by light conditions. Quenching of excess energy by PSI might be one of the physiological functions of PSI–PSII complexes.
Plants have two types of photosystem reaction centres, PSI and PSII, that are traditionally thought to be spatially separate. Here, Yokono
et al
. show in
Arabidopsis
that around half of PSII physically interacts with PSI to efficiently transfer excitation energy between the complexes, and this interaction is regulated by light.
Journal Article
A comparison of the ClotPro system with rotational thromboelastometry in cardiac surgery: a prospective observational study
Viscoelastic coagulation tests have been increasingly used for hemostasis management in cardiac surgery. The ClotPro system is a novel viscoelastic device based on principles of rotational thromboelastometry. We aimed to compare ClotPro with ROTEM and plasma coagulation assays in cardiopulmonary bypass (CPB) patients. Blood samples were collected from 25 CPB patients at (1) baseline, (2) start of CPB, (3) end of CPB, and (4) end of surgery. The EX-test, IN-test, HI-test, FIB-test parameters on ClotPro were compared with corresponding ROTEM assay (EXTEM, INTEM, HEPTEM, and FIBTEM). Standard plasma coagulation assays and endogenous thrombin generation (TG) were simultaneously evaluated. Pearson correlation analyses showed moderate correlations between clotting times (CTs) (r = 0.63–0.67; p < 0.001, respectively), and strong correlations with maximal clot firmness (MCF) (r = 0.93–0.98; p < 0.001, respectively) between ClotPro and ROTEM. EX-test and IN-test MCF parameters were interchangeable with acceptable percentage errors (EX-test MCF: 7.3%, IN-test MCF: 8.3%), but FIB-test MCF (27.0%) and CT results were not (EX-test CT: 44.7%, IN-test CT: 31.4%). The correlations of PT/INR or peak TG with EX-test CTs were higher than with EXTEM CTs (PT/INR: r = 0.80 and 0.41, peak TG: 0.43 and 0.18, respectively). FIB-test MCF has strong correlation with plasma fibrinogen and factor XIII level (r = 0.84 and 0.66, respectively). ROC analyses showed that ClotPro was capable of emulating well-established ROTEM thresholds (area under curves: 0.83–1.00). ClotPro demonstrated strong correlations in MCF parameters of ROTEM in CPB patients. It may be reasonable to modify ROTEM-based transfusion algorithm pertaining to MCF parameters to establish cut-off values for ClotPro device.
Journal Article
Adaptively mixed thin films for advanced optical coatings with reduced stress and tunable refractive index
A wide variety of optical components are used in optical instruments such as laser devices, spectrophotometers, cameras and telescopes. To enhance their performance, these components are often coated with optical thin films including antireflection (AR) coatings, high reflection (HR) coatings, polarizing films, translucent films, and bandpass filters. However, the fabrication of multilayer thin-film coatings is often constrained by stresses that arise during the deposition process. These stresses can lead to delamination, thereby limiting the range of dielectric materials and operating wavelengths available for optical components. We report a novel thin-film fabrication method that enables both refractive index control and significant stress reduction. This approach produces adaptively mixed thin films (AMTFs), consisting of dielectric material, polytetrafluoroethylene (PTFE), and depletion layers, with a porous microstructure that lowers refractive index while maintaining high transmittance. For example, AMTF: MgF₂ films exhibit a refractive index as low as 1.3, a 15-fold reduction in stress compared with pure MgF₂, and 95.95% transmittance. In addition to antireflection coatings, highly reflective multilayer mirrors can also be fabricated using structures such as [Al₂O₃/AMTF: Al₂O₃], [ZrO₂/AMTF: SiO₂], and [TiO₂/AMTF: MgF₂]. The range of applicable dielectric materials is thereby significantly expanded. By tailoring the refractive index, these films enable coverage of a broad spectral range from 200 nm to 7000 nm. The demonstrated reduction of stress, control over refractive index, and wide spectral applicability highlight the potential of AMTFs to advance the design and fabrication of next-generation optical coatings, particularly in the field of laser optics.
Journal Article
Complex strain evolution of polar and magnetic order in multiferroic BiFeO3 thin films
Electric-field control of magnetism requires deterministic control of the magnetic order and understanding of the magnetoelectric coupling in multiferroics like BiFeO
3
and EuTiO
3
. Despite this critical need, there are few studies on the strain evolution of magnetic order in BiFeO
3
films. Here, in (110)-oriented BiFeO
3
films, we reveal that while the polarization structure remains relatively unaffected, strain can continuously tune the orientation of the antiferromagnetic-spin axis across a wide angular space, resulting in an unexpected deviation of the classical perpendicular relationship between the antiferromagnetic axis and the polarization. Calculations suggest that this evolution arises from a competition between the Dzyaloshinskii–Moriya interaction and single-ion anisotropy wherein the former dominates at small strains and the two are comparable at large strains. Finally, strong coupling between the BiFeO
3
and the ferromagnet Co
0.9
Fe
0.1
exists such that the magnetic anisotropy of the ferromagnet can be effectively controlled by engineering the orientation of the antiferromagnetic-spin axis.
To fully exploit the potential of multiferroic materials the control of their intrinsic degrees of freedom is a prerequisite. Here, the control of spin orientation in strained BiFeO
3
films is demonstrated elucidating the microscopic mechanism of the complex interplay of polar and magnetic order.
Journal Article
Single-domain multiferroic BiFeO3 films
The strong coupling between antiferromagnetism and ferroelectricity at room temperature found in BiFeO
3
generates high expectations for the design and development of technological devices with novel functionalities. However, the multi-domain nature of the material tends to nullify the properties of interest and complicates the thorough understanding of the mechanisms that are responsible for those properties. Here we report the realization of a BiFeO
3
material in thin film form with single-domain behaviour in both its magnetism and ferroelectricity: the entire film shows its antiferromagnetic axis aligned along the crystallographic
b
axis and its ferroelectric polarization along the
c
axis. With this we are able to reveal that the canted ferromagnetic moment due to the Dzyaloshinskii–Moriya interaction is parallel to the
a
axis. Furthermore, by fabricating a Co/BiFeO
3
heterostructure, we demonstrate that the ferromagnetic moment of the Co film does couple directly to the canted moment of BiFeO
3
.
The coupling of ferroelectric and antiferromagnetic order in BiFeO
3
makes it appealing for applications however the presence of domain structure acts to undermine this potential. Here, the authors demonstrate BiFeO
3
thin films with a single domain of electrical polarization and canted antiferromagnetic order.
Journal Article
Non-invasive detection of regulatory T cells with Raman spectroscopy
Regulatory T cells (Tregs) are a type of lymphocyte that is key to maintaining immunological self-tolerance, with great potential for therapeutic applications. A long-standing challenge in the study of Tregs is that the only way they can be unambiguously identified is by using invasive intracellular markers. Practically, the purification of live Tregs is often compromised by other cell types since only surrogate surface markers can be used. We present here a non-invasive method based on Raman spectroscopy that can detect live unaltered Tregs by coupling optical detection with machine learning implemented with regularized logistic regression. We demonstrate the validity of this approach first on murine cells expressing a surface Foxp3 reporter, and then on peripheral blood human T cells. By including methods to account for sample purity, we could generate reliable models that can identify Tregs with an accuracy higher than 80%, which is already comparable with typical sorting purities achievable with standard methods that use proxy surface markers. We could also demonstrate that it is possible to reliably detect Tregs in fully independent donors that are not part of the model training, a key milestone for practical applications.
Journal Article
Yield variation of rainfed rice as affected by field water availability and N fertilizer use in central Benin
Rice is mainly grown under rainfed conditions in West Africa. Unpredictable and variable rainfall, poor soil quality, and suboptimal crop management practices are the main determinants of low productivity. We assessed the effects of soil water availability and fertilizer application, and their interaction on the yield of rainfed rice in Glazoué, Department of Zou-Collines, central Benin between 2010 and 2013. On-farm fertilizer management trials and field surveys were conducted in 13–39 farmers’ fields per year. Field water conditions were visually assessed three times per week during the rice-growing season and flood and drought indices were calculated on the basis of number of days with ponded water and dry surface soil relative to the total number of days for the vegetative, the reproductive and whole rice-growing period. Variations in flood and drought indices were related to the sand content of the soil. While nitrogen was the most limiting nutrient, average response to N fertilizer application was low with an agronomic N use efficiency of only 7–9 kg grain per kg of N applied. Year-to-year variation in rainfall and spatial variation in field water status affected both rice yield and response to N fertilizer. Some 47% of the observed yield variation was explained by field water status and the amounts of N fertilizer applied, with rice response to N fertilizer being less when water was limited. We conclude that the prevailing blanket fertilizer recommendations are unlikely to contribute to yield increases in rainfed systems of West Africa. There is a need for field-specific recommendations that consider soil texture and the spatial–temporal dynamics of water availability.
Journal Article
10 PW peak power femtosecond laser pulses at ELI-NP
We report on the generation and delivery of 10.2 PW peak power laser pulses, using the High Power Laser System at the Extreme Laser Infrastructure – Nuclear Physics facility. In this work we demonstrate for the first time, to the best of our knowledge, the compression and propagation of full energy, full aperture, laser pulses that reach a power level of more than 10 PW.
Journal Article
Luminous, relativistic, directional electron bunches from an intense laser driven grating plasma
Bright, energetic, and directional electron bunches are generated through efficient energy transfer of relativistic intense (~ 10
19
W/cm
2
), 30 femtosecond, 800 nm high contrast laser pulses to grating targets (500 lines/mm and 1000 lines/mm), under surface plasmon resonance (SPR) conditions. Bi-directional relativistic electron bunches (at 40° and 150°) are observed exiting from the 500 lines/mm grating target at the SPR conditions. The surface plasmon excited grating target enhances the electron flux and temperature by factor of 6.0 and 3.6, respectively, compared to that of the plane substrate. Particle-in-Cell simulations indicate that fast electrons are emitted in different directions at different stages of the laser interaction, which are related to the resultant surface magnetic field evolution. This study suggests that the SPR mechanism can be used to generate multiple, bright, ultrafast relativistic electron bunches for a variety of applications.
Journal Article