Rapid expansion of the invasive-like red macroalga, Chondria tumulosa (Rhodophyta), on the coral reefs of the Papahanaumokuakea Marine National Monument.

A cryptogenic, invasive-like red macroalga, Chondria tumulosa, was first observed in 2016 forming thick mats on the forereef of Manawai Atoll within Papahanaumokuakea Marine National Monument. Subsequent expeditions revealed an increased abundance of this alga. In 2021, unattached C. tumulosa was observed forming a network of dark, meandering accumulations throughout the atoll's inner lagoon. High-resolution satellite imagery revealed that these accumulations became visible in 2015 (length: ~0.74 km; area: ~0.88 km2 ) and increased 56-fold in length and 115-fold in area by 2021 (length: 41.32 km; area: 101.34 km2 ). An exponential expansion rate of ~16.02 km · y-1 (length), ~44.75 km2 · y-1 (area). This study presents the comprehensive temporal and spatial expansion of C. tumulosa accumulations for Manawai Atoll since its discovery, providing ecologist and resource managers with a proxy to gauge the overall abundance trend of this invasive-like alga.

Single-Molecule Magnetoluminescence from a Spatially Confined Persistent Diradical Emitter.

Luminescent radicals are an emerging class of materials that exhibit unique photofunctions not found in closed-shell molecules due to their open-shell electronic structure. Particularly promising are photofunctions in which radical's spin and luminescence are correlated; for example, when a magnetic field can affect luminescence (i.e., magnetoluminescence, ML). These photofunctions could be useful in the new science of spin photonics. However, previous observations of ML in radicals have been limited to systems in which radicals are randomly doped in host crystals or polymerized through metal complexation. This study shows that a covalently linked luminescent radical dimer (diradical) can exhibit ML as a single-molecular property. This facilitates detailed elucidation of the requirements for and mechanisms of ML in radicals and can aid the rational design of ML-active radicals based on synthetic chemistry.

Triarylamine-Substituted Benzimidazoliums as Electron Donor-Acceptor Dyad-Type Photocatalysts for Reductive Organic Transformations.

Triarylamine-substituted benzimidazoliums (BI+-PhNAr2), new electron donor-acceptor dyad molecules, were synthesized. Their photocatalytic properties for reductive organic transformations were explored using absorption and fluorescence spectroscopy, redox potential determinations, density functional theory calculations, transient absorption spectroscopy, and reduction reactions of selected substrates. The results show that irradiation of BI+-PhNAr2 promotes photoinduced intramolecular electron transfer to form a long-lived (∼300 µs) charge shifted state (BI•-PhN•+Ar2). In the pathway for photocatalysis of reduction reactions of substrates, BI•-PhN•+Ar2 is subsequently transformed to the neutral benzimidazolyl radical (BI•-PhNAr2) by single-electron transfer from the donor 1,3-dimethyl-2-phenylbenzimidazoline (BIH-Ph) serving as a cooperative agent. Among the benzimidazoliums explored, the bromo-substituted analogue BI+-PhN(C6H4Br-p)2 in conjunction with BIH-Ph demonstrates the most consistent catalytic performance.

Transient photocurrent and optical absorption of disordered thin-film semiconductors: In-depth injection and nonlinear response.

The time-of-flight method is a fundamental approach for characterizing the transport properties of semiconductors. Recently, the transient photocurrent and optical absorption kinetics have been simultaneously measured for thin films; pulsed-light excitation of thin films should give rise to non-negligible in-depth carrier injection. Yet, the effects of in-depth carrier injection on the transient currents and optical absorption have not yet been elucidated theoretically. Here, by considering the in-depth carrier injection in simulations, we found a 1/t1-α/2 initial time (t) dependence rather than the conventional 1/t1-α dependence under a weak external electric field, where α < 1 is the index of dispersive diffusion. The asymptotic transient currents are not influenced by the initial in-depth carrier injection and follow the conventional 1/t1+α time dependence. We also present the relation between the field-dependent mobility coefficient and the diffusion coefficient when the transport is dispersive. The field dependence of the transport coefficients influences the transit time in the photocurrent kinetics dividing two power-law decay regimes. The classical Scher-Montroll theory predicts that a1 + a2 = 2 when the initial photocurrent decay is given by 1/ta1 and the asymptotic photocurrent decay is given by 1/ta2 . The results shed light on the interpretation of the power-law exponent of 1/ta1 when a1 + a2 ≠ 2.

An Element-Substituted Cyclobutadiene Exhibiting High-Energy Blue Phosphorescence.

1,3,2,4-Diazadiboretidine, an isoelectronic heteroanalogue of cyclobutadiene, is an interesting chemical species in terms of comparison with the carbon system, whereas its properties have never been investigated experimentally. According to Baird's rule, Hückel antiaromatic cyclobutadiene acquires aromaticity in the lowest triplet state. Here we report experimental and theoretical studies on the ground- and excited-state antiaromaticity/aromaticity as well as the photophysical properties of an isolable 1,3,2,4-diazadiboretidine derivative. The crystal structure of the diazadiboretidine derivative revealed that the B2 N2 ring adopts a planar rhombic geometry in the ground state. Yet, theoretical calculations showed that the B2 N2 ring turns to a square geometry with a nonaromatic character in the lowest triplet state. Notably, the diazadiboretidine derivative has the lowest singlet and triplet states lying at close energy levels and displays blue phosphorescence.

Photogenerated Radical Pair between Flavin and a Tryptophan-Containing Transmembrane-Type Peptide in a Large Unilamellar Vesicle.

Electron-transfer (ET) reactions in biological systems, such as those with magnetic sensors based on flavoproteins and electron transport at biomembrane interfaces, are interesting and important issues that require understanding. As a model system of flavoproteins in biomimetic environments, we report the dynamics of the radical pair generated by photoinduced ET between riboflavin tetrabutylate (RFTB) and tryptophan (Trp) residues in a transmembrane-type polypeptide, both of which are distributed in a large unilamellar vesicle of 1,2-dimyristoyl-sn-glycero-3-phosphocholine. The Trp residues locate near the hydrophilic membrane interface, as confirmed by a dual-fluorescence quenching assay. The fluorescence and transient absorption upon photoexcitation of RFTB indicate that ET from both the singlet and triplet excited states occurs at the hydrophilic interface, whereas the RFTB in the hydrophobic region does not contribute to ET. The ET efficiency and the magnetic field effect (MFE) on the RFTB anion increase significantly above the gel-to-liquid crystal phase transition temperature due to a decrease in microviscosity. The MFE analysis indicates that the radical pair generated from the triplet ET channel exhibits a long lifetime as those in micellar systems due to the strong cage effect of the vesicle.

Peak autumn leaf colouring along latitudinal and elevational gradients in Japan evaluated with online phenological data.

We evaluated the spatial characteristics of the first day of peak leaf colouring (PLCstart) and their relationships with air temperature along latitudinal and elevational gradients in Japan from 2015 to 2017. Leaf colouring information collected from more than 740 sites via citizen science was analysed, representing elevations from 0 to 2800 m and latitudes from 32°N to 44°N. We found that locations with earlier PLCstart dates (day of year 265-294) displayed steeper slopes in elevation per degree of latitude than locations with later PLCstart dates (day of year 295-314). This statistically significant result indicates that the influence of elevation on PLCstart (vertical gradient) weakened as the leaf colouring season progressed in Japan. In addition to these spatial characteristics, the PLCstart and the warmth index (based on monthly mean air temperature) showed significant linear correlations for latitudinal and elevational gradients. This result suggests that the sensitivity of PLCstart to air temperature, as manifested in both latitudinal and elevational gradients, is constant. This study suggests that online phenological data may provide more accurate results for a regional scale (100-1000 km) than the datasets used by previous studies.

Cultivation potential projections of breadfruit (Artocarpus altilis) under climate change scenarios using an empirically validated suitability model calibrated in Hawai'i.

Humanity faces significant challenges to agriculture and human nutrition, and changes in climate are predicted to make such challenges greater in the future. Neglected and underutilized crops may play a role in mitigating and addressing such challenges. Breadfruit is a long-lived tree crop that is a nutritious, carbohydrate-rich staple, which is a priority crop in this regard. A fuzzy-set modeling approach was applied, refined, and validated for breadfruit to determine its current and future potential productivity. Hawai'i was used as a model system, with over 1,200 naturalized trees utilized to calibrate a habitat suitability model and 56 producer sites used to validate the model. The parameters were then applied globally on 17 global climate models at the RCP 4.5 and RCP 8.5 global climate projections for 2070. Overall, breadfruit suitability increases in area and in quality, with larger increases occurring in the RCP 8.5 projection. Current producing regions largely remain unchanged in both projections, indicating relative stability of production potential in current growing regions. Breadfruit, and other tropical indigenous food crops present strong opportunities for cultivation and food security risk management strategies moving forward.

Spin-dependent electron transfer dynamics in a platinum-complex-donor-acceptor triad studied by transient-absorption detected magnetic field effect.

For realization of efficient organic light-energy conversion systems, controlling the lifetime of photogenerated charge separated states in donor (D)-acceptor (A) molecules is of much importance; the spin dynamics is one of the important controlling factors. We previously reported that the covalently-linked 1,3-bis(2-pyridylimino)-isoindolate platinum (BPIPt)-dimethoxytriphenylamine (D)-naphthaldiimide (A) triad molecule (BPIPt-DA) exhibits a triplet-born long-lived charge separated state (BPIPt-D•+A•-), the lifetime of which is significantly increased from 4 µs to 10 µs by an applied magnetic field of 270 mT in room temperature tetrahydrofuran (THF). The purpose of the present study is to clarify detailed dynamics of spin-dependent generation and the decay of BPIPt-D+A-. For this purpose, we measured transient optical absorption (TA) and the TA-detected magnetic field effect (MFE) as functions of temperature and dispersion media. In THF at 183 K, MFE-detected transient spectra of the intermediate BPIPt•--D•+A state are observed. We have successfully quantified the recombination loss at this state by a kinetic simulation of MFE without using any reference molecules. The lifetime of the final BPIPt-D•+A•- state in a cellulose acetate polymer matrix at room temperature is significantly prolonged to 20 µs at 0 mT and 96 µs at 250 mT compared to those in THF. From the comparison of temperature dependences of the two media, effects of molecular motions on the electronic coupling and the spin relaxation are discussed.

Mania induced by isoniazid preventive therapy during steroid treatment for rheumatoid arthritis and organising pneumonia.

Isoniazid preventative therapy is widely used for latent tuberculosis infection. Isoniazid is highly effective but has many adverse effects, including neuropsychiatric. We describe the case of an 80-year-old woman with mania. She had received isoniazid preventative therapy during steroid treatment for rheumatoid arthritis and organising pneumonia for the previous 5 months. Her mania resolved after discontinuation of isoniazid. Adverse effects of isoniazid should be considered even if a long time has elapsed since the start of administration. Physicians other than infectious disease and respiratory specialists also must be aware of the adverse effects of isoniazid preventative therapy.

Improved Characterisation of Vegetation and Land Surface Seasonal Dynamics in Central Japan with Himawari-8 Hypertemporal Data.

Spectral vegetation index time series data, such as the normalized difference vegetation index (NDVI), from moderate resolution, polar-orbiting satellite sensors have widely been used for analysis of vegetation seasonal dynamics from regional to global scales. The utility of these datasets is often limited as frequent/persistent cloud occurrences reduce their effective temporal resolution. In this study, we evaluated improvements in capturing vegetation seasonal changes with 10-min resolution NDVI data derived from Advanced Himawari Imager (AHI), one of new-generation geostationary satellite sensors. Our analysis was focused on continuous monitoring sites, representing three major ecosystems in Central Japan, where in situ time-lapse digital images documenting sky and surface vegetation conditions were available. The very large number of observations available with AHI resulted in improved NDVI temporal signatures that were remarkably similar to those acquired with in situ spectrometers and captured seasonal changes in vegetation and snow cover conditions in finer detail with more certainty than those obtained from Visible Infrared Imaging Radiometer Suite (VIIRS), one of the latest polar-orbiting satellite sensors. With the ability to capture in situ-quality NDVI temporal signatures, AHI "hypertemporal" data have the potential to improve spring and autumn phenology characterisation as well as the classification of vegetation formations.

Effects of the Peripheral Substituents, Central Metal, and Solvent on the Photochemical and Photophysical Properties of 5,15-Diazaporphyrins.

Metal complexes of 3,7,13,17-tetrakis(di(4-carboxyphenyl)amino)-5,15-diazaporphyrin (MDAP-COOH; M=Pd, Cu) and their ethyl ester precursors (MDAP-COOEt; M=Pd, Cu) have been synthesized for use as near-infrared (NIR)-light-responsive photosensitizers. Under irradiation with visible or NIR light, PdDAP-COOEt in toluene generated singlet oxygen (1 O2 ) with an excellent quantum yield (ΦΔ =0.99), whereas CuDAP-COOEt exhibited a lower efficiency (ΦΔ =0.21). The water-soluble PdII complex PdDAP-COOH also behaved as a photosensitizer (ΦΔ =0.20) in a micellar solution. The photophysical properties of these dyes were measured by transient absorption techniques. It was found that the efficiency of the energy transfer from the triplet state of MDAP-COOR (R=Et, H) to the ground state of dioxygen was highly dependent on the peripheral substituents, the central metal, and the solvent. Furthermore, the phototoxicity of PdDAP-COOH toward HeLa cells under irradiation of NIR light (720 nm) was evaluated. As expected, PdDAP-COOH exhibited good photodynamic activity, and control experiments confirmed that 1 O2 was generated as the active oxygen species.

Gigantic Magnetic Field Effect on the Long-Lived Intermolecular Charge-Separated State Created at the Nonionic Bilayer Membrane.

For realization of low-cost organic photon-energy conversion, the supramolecular approach has been a focus of attention as a counter approach to precise synthesis of covalently linked donor (D)-acceptor (A) molecules. Here we report photogeneration of a long-lived (∼3 µs) intermolecular charge-separated (CS) state of metal porphyrins (D) and an alkyl viologen (A) at an interface of a vesicle membrane formed by self-assembly of nonionic surfactant and cholesterol molecules. The yield of escaped free radicals is negligibly low as in the case of CS states in covalently linked D-A systems. Furthermore, the transient concentration of the CS state dramatically increases by ∼100% upon application of a magnetic field of 250 mT at room temperature. The simulation of the spin dynamics of the CS state indicates that fast (∼107 s-1) spin-selective recombination and slow (105-106 s-1) dissociation-re-encounter dynamics are the key processes for the long CS-state lifetime and the gigantic magnetic field effect. It has turned out that such dynamics are sharply dependent on temperature and alkyl chain length of the viologen. The present results would lead to the development of future materials for light energy conversion, drug delivery, and microscopic bioprobes.

Visible Light and Hydroxynaphthylbenzimidazoline Promoted Transition-Metal-Catalyst-Free Desulfonylation of N-Sulfonylamides and N-Sulfonylamines.

A visible light promoted process for desulfonylation of N-sulfonylamides and -amines has been developed, in which 1,3-dimethyl-2-hydroxynaphthylbenzimidazoline (HONap-BIH) serves as a light absorbing, electron and hydrogen atom donor, and a household white light-emitting diode serves as a light source. The process transforms various N-sulfonylamide and -amine substrates to desulfonylated products in moderate to excellent yields. The observation that the fluorescence of 1-methyl-2-naphthoxy anion is efficiently quenched by the substrates suggests that the mechanism for the photoinduced desulfonylation reaction begins with photoexcitation of the naphthoxide chromophore in HONap-BIH, which generates an excited species via intramolecular proton transfer between the HONap and BIH moieties. This process triggers single electron transfer to the substrate, which promotes loss of the sulfonyl group to form the free amide or amine. The results of studies employing radical probe substrates as well as DFT calculations suggest that selective nitrogen-sulfur bond cleavage of the substrate radical anion generates either a pair of an amide or amine anion and a sulfonyl radical or that of an amidyl or aminyl radical and sulfinate anion, depending on the nature of the N-substituent on the substrate. An intermolecular version of this protocol, in which 1-methyl-2-naphthol and 1,3-dimethyl-2-phenylbenzimidazoline are used concomitantly, was also examined.

Quantifying urban growth patterns in Hanoi using landscape expansion modes and time series spatial metrics.

Urbanization has been driven by various social, economic, and political factors around the world for centuries. Because urbanization continues unabated in many places, it is crucial to understand patterns of urbanization and their potential ecological and environmental impacts. Given this need, the objectives of our study were to quantify urban growth rates, growth modes, and resultant changes in the landscape pattern of urbanization in Hanoi, Vietnam from 1993 to 2010 and to evaluate the extent to which the process of urban growth in Hanoi conformed to the diffusion-coalescence theory. We analyzed the spatiotemporal patterns and dynamics of the built-up land in Hanoi using landscape expansion modes, spatial metrics, and a gradient approach. Urbanization was most pronounced in the periods of 2001-2006 and 2006-2010 at a distance of 10 to 35 km around the urban center. Over the 17 year period urban expansion in Hanoi was dominated by infilling and edge expansion growth modes. Our findings support the diffusion-coalescence theory of urbanization. The shift of the urban growth areas over time and the dynamic nature of the spatial metrics revealed important information about our understanding of the urban growth process and cycle. Furthermore, our findings can be used to evaluate urban planning policies and aid in urbanization issues in rapidly urbanizing countries.

Computational study on formation of 15-membered azalactone by double reductive amination using molecular mechanics and density functional theory calculations.

Formation of 15-membered azalactone by double reductive amination was analyzed using molecular mechanics and density functional theory calculations for simplified model compounds. As a result, the following aspects were clarified. When methylamine attacks a linear bis-aldehyde in the first step, there are possibilities that two regioisomers are formed. However, one of them exhibited remarkably stable energy level compared with the other. The stable isomer indicated a short distance between a methylamine moiety and an unreacted aldehyde. This short distance, about 2.3 Å, could be explained by hydrogen bonding, which implied relatively easy cyclization in the second step. Moreover, this cyclization process was supposed to be exothermic according to comparison of energy levels before and after cyclization.

Benzimidazolium Naphthoxide Betaine Is a Visible Light Promoted Organic Photoredox Catalyst.

Benzimidazolium naphthoxide (-ONap-BI+) was first synthesized and utilized as an unprecedented betaine photoredox catalyst. Photoexcited state of -ONap-BI+ generated by visible light irradiation catalyzes the reductive deiodination as well as desulfonylation reactions in which 1,3-dimethyl-2-phenylbenzimidazoline (Ph-BIH) cooperates with as an electron and hydrogen atom donor. Significant solvent effects on the reaction progress were discovered, and specific solvation toward imidazolium and naphthoxide moieties of -ONap-BI+ was proposed.

Magnetoconductance Study on Nongeminate Recombination in Solar Cell Using Poly(3-hexylthiophene) and [6,6]-Phenyl-C61-butyric Acid Methyl Ester.

The magnetoconductance (MC) effect was investigated for two types of organic solar cells with single junction (SJ) and bulk junction (BJ) of poly(3-hexylthiophene) (P3HT) as donor (D) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as acceptor (A). Three components with different half-field-at-half-maximums (B 1/2) of 4 ± 1, 20 ± 15 and >400 mT, hereafter referred to MCS,M,B in a sequence, were observed in the magnetic field dependence of the MC effects measured under dark and light conditions. The magnitude of the MCS,M,B components is sensitive to not only the junction structure of the cell but also the presence or absence of incident light. The bias voltage (V) dependence of the MC effect in the dark for the SJ-cell is maximized around the turn-on voltage (V ON) of the dark current, where a flat band condition of the active layer is achieved. The B 1/2 for the MCM component of the SJ-cell increases with V beyond V ON. In light, the BJ-cell exhibits the MC effect, whereas no effect is detected for the SJ-cell. The MCS,M components for the BJ-cell in light increase with the incident light power. The transient MCS,M components for the BJ-cell measured using a nanosecond pulse laser increases with the delay time after the flash. By integrating these phenomena and the phase of the MC effect, it is concluded that all of the MC components arise from the magnetic field effect on the spin conversion of nongeminate electron (e)-hole (h) pairs with spin-dependent charge recombinations at the D/A-interface. The B 1/2 values for MCS,M,B are, respectively, understood by the spin conversion due to the hyperfine interaction, the spin relaxation, and the g-factor difference for e (PCBM-) and h (P3HT+). Kinetic simulations of the MCS,M components for the BJ-cell observed at the short-circuit condition in light yield an efficiency of ca. 40% for the nongeminate recombination, which is accompanied by the generation of triplet excitons as well as relaxation to a ground singlet state. The loss mechanism of moderate triplet recombination suggests an important possibility to improve the power conversion efficiency by harvesting of the triplet excitons.

Biological processes dominate seasonality of remotely sensed canopy greenness in an Amazon evergreen forest.

Satellite observations of Amazon forests show seasonal and interannual variations, but the underlying biological processes remain debated. Here we combined radiative transfer models (RTMs) with field observations of Amazon forest leaf and canopy characteristics to test three hypotheses for satellite-observed canopy reflectance seasonality: seasonal changes in leaf area index, in canopy-surface leafless crown fraction and/or in leaf demography. Canopy RTMs (PROSAIL and FLiES), driven by these three factors combined, simulated satellite-observed seasonal patterns well, explaining c. 70% of the variability in a key reflectance-based vegetation index (MAIAC EVI, which removes artifacts that would otherwise arise from clouds/aerosols and sun-sensor geometry). Leaf area index, leafless crown fraction and leaf demography independently accounted for 1, 33 and 66% of FLiES-simulated EVI seasonality, respectively. These factors also strongly influenced modeled near-infrared (NIR) reflectance, explaining why both modeled and observed EVI, which is especially sensitive to NIR, captures canopy seasonal dynamics well. Our improved analysis of canopy-scale biophysics rules out satellite artifacts as significant causes of satellite-observed seasonal patterns at this site, implying that aggregated phenology explains the larger scale remotely observed patterns. This work significantly reconciles current controversies about satellite-detected Amazon phenology, and improves our use of satellite observations to study climate-phenology relationships in the tropics.