Search

The medium-entropy alloy CrCoNi is known to have exceptional mechanical properties. To clarify its local structure, we performed extended x-ray absorption fine structure measurement of CrCoNi. The structural disorder is larger in Cr sites than in other constituent elements, which is consistent with the larger atomic displacement of the Cr atoms predicted by previous first-principles calculations. The Cr atom has a solute-type characteristic that induces local disorder. The differences in local disorder among the constituent elements decrease as the annealing time increases in the temperature range in which a short-range order develops. [ABSTRACT FROM AUTHOR]

Future projections on irrigation water under a changing climate are highly dependent on meteorological data derived from general circulation models (GCMs). Since climate projections include biases, bias correction is widely used to adjust meteorological elements, such as the atmospheric temperature and precipitation, but less attention has been paid to biases in humidity. Hence, in many cases, uncorrected humidity data have been directly used to analyze the impact of future climate change. In this study, we examined how the biases remaining in the humidity data of five GCMs propagate into the estimation of irrigation water demand and consumption from rivers using the global hydrological model (GHM) H08. First, to determine the effects of humidity bias across GCMs, we ran H08 with GCM-based meteorological forcing data sets distributed by the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP). A state-of-the-art bias correction method was applied to the data sets without correcting biases in humidity. Differences in the monthly relative humidity amounted to 11.7 to 20.4%RH (percentage relative humidity) across the GCMs and propagated into differences in the estimated irrigation water demand, resulting in a range between 1152.6 and 1435.5 km³ yr-1 for 1971-2000. Differences in humidity also propagated into future projections. Second, sensitivity analysis with hypothetical humidity biases of ±5%RH added homogeneously worldwide revealed the large negative sensitivity of irrigation water abstraction in India and East China, which are heavily irrigated. Third, we performed another set of simulations with bias-corrected humidity data to examine whether bias correction of the humidity can reduce uncertainties in irrigation water across the GCMs. The results showed that bias correction, even with a primitive methodology that only adjusts the monthly climatological relative humidity, helped reduce uncertainties across the GCMs: by using bias-corrected humidity data, the uncertainty ranges of irrigation water demand across the five GCMs were successfully reduced from 282.9 to 167.0 km³ yr-1 for the present period, and from 381.1 to 214.8 km³ yr-1 for the future period (RCP8.5, 2070-2099). Although different GHMs have different sensitivities to atmospheric humidity because different types of potential evapotranspiration formulae are implemented in them, bias correction of the humidity should be applied to forcing data, particularly for the evaluation of evapotranspiration and irrigation water. [ABSTRACT FROM AUTHOR]

Future projections on irrigational water under a changing climate are highly dependent on meteorological data derived from general circulation models (GCMs). Since climate projections include biases, bias correction is widely used to adjust meteorological ele- ments, such as the atmospheric temperature and precipitation, but less attention has been paid to biases in humidity. Hence, in many cases, raw GCM outputs have been directly used to analyze the impact of future climate change. In this study, we examined how the biases remaining in the humidity data of five GCMs propagate into the estimation of irrigational water demand and abstraction from rivers using the global hydrolog ical model (GHM) H08. First, to determine the effects of humidity bias across GCMs, we used meteorological data sets to which a state-of-the-art bias correction method was applied except to the humidity. Uncorrected GCM outputs were used for the humidity. We found that differences in the monthly relative humidity of 11.7 to 20.4%RH (percent used as the unit of relative humidity) from observations across the GCMs caused the estimated irrigational water abstraction from rivers to range between 1217.7 and 1341.3 km3 yr-1 for 1971-2000. Differences in humidity also propagate into future projections. Second, sensitivity analysis with hypothetical humidity biases of ± 5%RH added homogeneously worldwide revealed the large negative sensitivity of irrigational water abstraction in India and East China, which have high areal fractions of irrigated cropland. Third, we performed another set of simulations with bias-corrected humidity data to examine whether bias correction of the humidity can reduce uncertainties in irrigational water across the GCMs. The results showed that bias correction, even with a primitive methodology that only adjusts the monthly climatological relative humidity, helped reduce uncertainties across the GCMs. Although the GHMs have different sensitivities to atmospheric humidity because of the implementation of different types of potential evapotranspiration formulae, bias correction of the humidity should be included in hydrological analysis, particularly for the evaluation of evapotranspiration and irrigational water. [ABSTRACT FROM AUTHOR]

In the intermetallic SmNiC2, the ferromagnetic metallic state competes with the charge-density-wave state. We can switch the charge-density-wave state by applying a magnetic field that is conjugated to the magnetization of the order parameter in the ferromagnetic state, and show the giant negative magnetoresistance. Under the applied magnetic field, the resistivity becomes one order of magnitude smaller than the zero-field resistivity. [ABSTRACT FROM AUTHOR]

We synthesized TPP[FeIII(Pc)(CN)2]2, PTMAx[FeIII(Pc)(CN)2]·y(MeCN), and PXX [FeIII(Pc)(CN)2], a new series of charge-transfer salts containing the axially-substituted phthalocyanine (Pc), [FeIII(Pc)(CN)2]−. In this molecular unit, the π conduction electron derived from the Pc-ring coexists with the d electron which is a potential source of a local magnetic moment. Therefore various phenomena associated with the interplay between local magnetic moments and conduction electrons are expected. We observed the giant negative magnetoresistance (GNMR) in all the three salts. The GNMR is highly anisotropic for the magnetic-field direction, and reflects the g-tensor anisotropy of the local magnetic moment in the [FeIII(Pc)(CN)2]− unit. This indicates that the GNMR in these salts originates from the strong π–d interaction in the [FeIII(Pc)(CN)2]− unit. [Copyright &y& Elsevier]

The magnetoresistance study on TPP[M(Pc)(CN)2]2 (M=Fe, Co, Fe0.30Co0.70) salts is reported. These three salts have similar columnar structures, nevertheless exhibit different electrical behaviors. TPP[Fe(Pc)(CN)2]2 exhibits anisotropic giant negative magnetoresistance, while TPP[Co(Pc)(CN)2] exhibits large positive magnetoresistance. The alloyed compound, TPP[Fe0.30Co0.70 (Pc)(CN)2]2, also exhibits anisotropic negative magnetoresistance, although the decrease in the resistivity under the magnetic field is less than that of TPP[Fe(Pc)(CN)2]2. The g-tensor anisotropy in the [Fe(Pc)(CN)2] unit qualitatively explains the field-orientation dependence of the negative magnetoresistance. Magnetic fluctuation associated with a weak-ferromagnetic transition is suggested as a possible origin of the giant negative magnetoresistance. [Copyright &y& Elsevier]

Magnetic structures of the noncentrosymmetric magnet Sr2MnSi2O7 were examined through neutron diffraction for powder and single‐crystalline samples, as well as magnetometry measurements. All allowed magnetic structures for space group P421m with the magnetic wavevector qm = (0, 0, ½) were refined via irreducible representation and magnetic space group analyses. The compound was refined to have in‐plane magnetic moments within the magnetic space group Cmc21.1′c (No. 36.177) under zero field, which can be altered to P212121.1′c (No. 19.28) above μ0H = 0.067 (5) T to align induced weak‐ferromagnetic components within one layer on the ab plane. All refined parameters are provided following the recent framework based upon the magnetic space group, which better conveys when exchanging crystallographic information for commensurate magnetic structures. [ABSTRACT FROM AUTHOR]

TaAs single crystals were grown by a standard chemical vapor transport method. The single-crystallinity and homogeneous distribution of elements were confirmed by transmission electron microscope and x-ray diffraction observations. Positron annihilation measurements revealed that the atomic vacancy concentration was kept below 10 − 5 at. %. However, inductively coupled plasma analysis showed an As-deficient (7–9 at. %) off-stoichiometry. First-principles calculations implied that the off-stoichiometry could be compensated for with excess Ta antisite defects, thereby inducing metallic states. Nevertheless, excellent semimetallic transport properties of a well-suppressed carrier density (≲ 10 18 cm − 3 ), ultrahigh carrier mobility (≳ 10 6 cm 2 /V/s), and large transverse magnetoresistance (> --> 200 000 % at 9 T) with the quantum oscillation were obtained at 1.7 K. This indicated the robustness of semimetallic transport properties against the off-stoichiometric disorder and the quenching of metallic conduction associated with excess Ta atoms. The negative longitudinal magnetoresistance, which is considered evidence of a Weyl semimetal (chiral anomaly), was not observed. These data were discussed with theoretical calculations. [ABSTRACT FROM AUTHOR]

We measured the electron spin resonance and the magnetoresistance in the iron(III) phthalocyanine complexes. The electron spin resonance in PNP[Fe(Pc)(CN)2] reveals the large anisotropy of the g-value. This is due to the strong spin–orbit coupling in the second HOMO (the third HOMO) hybridizing the dyz (dzx) orbital in the central Fe atom. This anisotropic g-value is consistent with the anisotropy of the magnetic susceptibility and the negative magnetoresistance in TPP[Fe(Pc)(CN)2]2. We also measured the large negative magnetoresistance in [PXX][Fe(Pc)(CN)2] and (PTMA)x[Fe(Pc)(CN)2]Y(CH3CN). The iron(III) phthalocyanine complexes are the good materials for the research of the one-dimensional π–d electron system. [Copyright &y& Elsevier]

The correlation between the charge density wave (CDW) and f local moments is observed in GdNiC2 by means of x-ray diffraction in a magnetic field. Various kinds of electronic states exist in the magnetic field. The intensity of the CDW peak changes in the successive transitions and the commensurate-incommensurate transition of the CDW takes place as well. The successive transitions are explained in terms of a cooperative effect of the Peierls instability and the spin Friedel oscillation, in which the antiferromagnetic order of the f local moments is coupled to the spin density wave coexisting with the CDW of the conduction electron. [ABSTRACT FROM AUTHOR]

We have measured the angular dependence of the ESR spectra on DMDP[FeIII0.01CoIII0.99(Pc)(CN)2] (DMDP=dimethyldiphenylphosphonium, Pc=phthalocyanine), which is the alloy system of magnetic FeIII and non-magnetic CoIII. The spectra exhibit giant anisotropic shift in g-value of iron(III). We also report the temperature dependence of the polarized reflectance spectra of one-dimensional conductors, TPP[FeIII(Pc)(CN)2]2 and TPP[CoIII(Pc)(CN)2]2 (TPP=tetraphenylphosphonium). With lowering the temperature, the plasma edge drastically shifts to a higher wavenumber in both salts. [Copyright &y& Elsevier]

To sustain growing food demand and increasing standard of living, global water use increased by nearly 6 times during the last 100 years, and continues to grow. As water demands get closer and closer to the water availability in many regions, each drop of water becomes increasingly valuable and water must be managed more efficiently and intensively. However, soaring water use worsens water scarcity conditions already prevalent in semi-arid and arid regions, increasing uncertainty for sustainable food production and economic development. Planning for future development and investments requires that we prepare water projections for the future. However, estimations are complicated because the future of the world's waters will be influenced by a combination of environmental, social, economic, and political factors, and there is only limited knowledge and data available about freshwater resources and how they are being used. TheWater Futures and Solutions (WFaS) initiative coordinates its work with other ongoing scenario efforts for the sake of establishing a consistent set of new global water scenarios based on the shared socio-economic pathways (SSPs) and the representative concentration pathways (RCPs). The WFaS "fasttrack" assessment uses three global water models, namely H08, PCR-GLOBWB, and WaterGAP. This study assesses the state of the art for estimating and projecting water use regionally and globally in a consistent manner. It provides an overview of different approaches, the uncertainty, strengths and weaknesses of the various estimation methods, types of management and policy decisions for which the current estimation methods are useful. We also discuss additional information most needed to be able to improve water use estimates and be able to assess a greater range of management options across the water-energy-climate nexus. [ABSTRACT FROM AUTHOR]

To sustain growing food demand and increasing standard of living, global water use increased by nearly 6 times during the last 100 years and continues to grow. As water demands get closer and closer to the water availability in many regions, each drop of water becomes increasingly valuable and water must be managed more efficiently and intensively. However, soaring water use worsens water scarcity condition already prevalent in semi-arid and arid regions, increasing uncertainty for sustainable food production and economic development. Planning for future development and investments requires that we prepare water projections for the future. However, estimations are complicated because the future of world's waters will be influenced by a combination of environmental, social, economic, and political factors, and there is only limited knowledge and data available about freshwater resources and how they are being used. The Water Futures and Solutions initiative (WFaS) coordinates its work with other on-going scenario efforts for the sake of establishing a consistent set of new global water scenarios based on the Shared Socioeconomic Pathways (SSPs) and the Representative Concentration Pathways (RCPs). The WFaS "fast-track" assessment uses three global water models, namely H08, PCR-GLOBWB, and WaterGAP. This study assesses the state of the art for estimating and projecting water use regionally and globally in a consistent manner. It provides an overview of different approaches, 20 the uncertainty, strengths and weaknesses of the various estimation methods, types of management and policy decisions for which the current estimation methods are useful. We also discuss additional information most needed to be able to improve water use estimates and be able to assess a greater range of management options across the water-energy-climate nexus. [ABSTRACT FROM AUTHOR]

We report the synthesis of a new phthalocyanine–molecular mixed crystal, TPP[Cr x Co 1− x (Pc)(CN) 2 ] 2 , by an electrochemical method using a dilute solution. For the whole range of x , the chemical composition of the obtained single crystals is homogeneous and nearly equal to the nominal one in the dilution solution, as revealed by energy-dispersive X-ray spectroscopy. We have found that the concentrations of the starting materials play a vital role in the homogeneous growth of mixed crystals. [ABSTRACT FROM AUTHOR]

X-ray scattering and electrical resistivity measurements were performed on GdNiC2 and TbNiC2. We found a set of satellite peaks characterized by q1=(0.5,η,0) below T1, at which the resistivity shows a sharp inflection, suggesting the charge density wave (CDW) formation. The value of η decreases with decreasing temperature below T1, and then a transition to a commensurate phase with q1C=(0.5,0.5,0) takes place. The diffuse scattering observed above T1 indicates the presence of soft phonon modes associated with CDW instabilities at q1 and q2=(0.5,0.5,0.5). The long-range order given by q2 is developed in addition to that given by q1C in TbNiC2, while the short-range correlation with q2 persists even at 6 K in GdNiC2. The amplitude of the q1C lattice modulation is anomalously reduced below an antiferromagnetic transition temperature TN in GdNiC2. In contrast, the q2 order vanishes below TN in TbNiC2. We demonstrate that RNiC2 (R = rare earth) compounds exhibit similarities with respect to their CDW phenomena, and discuss the effects of magnetic transitions on CDWs. We offer a possible displacement pattern of the modulated structure characterized by q1C and q2 in terms of frustration. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate that the ferromagnetic intramolecular π−d interaction works between an itinerant π-electron spin and a localized d-electron's magnetic moment in the iron-phthalocyanine (Pc) molecular compound. The evaluation of the hidden π−d coupling is achieved by preparing the isolated Fe(Pc)(CN)2 molecular solution with unpaired π- and d-electron spins, which is generated through the oxidization by iodine bromide (IBr). The monotonic increase of the magnetization with IBr addition and the saturation value of the Curie constant indicate the ferromagnetic π−d coupling. Furthermore, through the magnetization measurements of the single crystals of neutral π radical Fe(Pc)(CN)2·2CHCl3, we reveal that the on-site π−d interaction in Fe(Pc)(CN)2 is extremely large (Jπd/kB>500K) among those in other molecular materials. [ABSTRACT FROM AUTHOR]

During the past decades large-scale models have been developed to simulate global and continental terrestrial water cycles. It is an open question whether these models are suitable to capture hydrological drought, in terms of runoff, on a global scale. A multimodel ensemble analysis was carried out to evaluate if 10 such large-scale models agree on major drought events during the second half of the twentieth century. Time series of monthly precipitation, monthly total runoff from 10 global hydrological models, and their ensemble median have been used to identify drought. Temporal development of area in drought for various regions across the globe was investigated. Model spread was largest in regions with low runoff and smallest in regions with high runoff. In vast regions, correlation between runoff drought derived from the models and meteorological drought was found to be low. This indicated that models add information to the signal derived from precipitation and that runoff drought cannot directly be determined from precipitation data alone in global drought analyses with a constant aggregation period. However, duration and spatial extent of major drought events differed between models. Some models showed a fast runoff response to rainfall, which led to deviations from reported drought events in slowly responding hydrological systems. By using an ensemble of models, this fast runoff response was partly overcome and delay in drought propagating from meteorological drought to drought in runoff was included. Finally, an ensemble of models also allows for consideration of uncertainty associated with individual model structures. [ABSTRACT FROM AUTHOR]

Climate change is expected to alter the hydrological cycle resulting in large-scale impacts on water availability. However, future climate change impact assessments are highly uncertain. For the first time, multiple global climate (three) and hydrological models (eight) were used to systematically assess the hydrological response to climate change and project the future state of global water resources. This multi-model ensemble allows us to investigate how the hydrology models contribute to the uncertainty in projected hydrological changes compared to the climate models. Due to their systematic biases, GCM outputs cannot be used directly in hydrological impact studies, so a statistical bias correction has been applied. The results show a large spread in projected changes in water resources within the climate- hydrology modelling chain for some regions. They clearly demonstrate that climate models are not the only source of uncertainty for hydrological change, and that the spread resulting from the choice of the hydrology model is larger than the spread originating from the climate models over many areas. But there are also areas showing a robust change signal, such as at high latitudes and in some midlatitude regions, where the models agree on the sign of projected hydrological changes, indicative of higher confidence in this ensemble mean signal. In many catchments an increase of available water resources is expected but there are some severe decreases in Central and Southern Europe, the Middle East, the Mississippi River basin, southern Africa, southern China and south-eastern Australia. [ABSTRACT FROM AUTHOR]

The article discusses a study on the effect of climate change on available water resources using hydrology and multiple global climate models. It states that a large spread of climate change projection in water resources in the climate-hydrology modeling chain. It concludes that the impact of climate change does not only rely on climate models and emission scenarios.

Abstract: We report a synchrotron X-ray study of charge density waves (CDWs) in an o- crystal. CDW of o- has been known to undergo a commensurate–incommensurate transition at 100K, below which the wavevector locks in with the pristine lattice. However, the details of the commensurate–incommensurate transition remain open problems, the example being whether the discommensuration exists or not in the neighborhood of the transition. We exploited the beamline BL02B1 of SPring-8. A two-dimensional detector was placed at a distance of 1300mm from the sample, providing an angle resolution of 0.0076°. Temperature dependence of the Bragg peak (002) and satellite peak was measured from 7 to 180K. We found that a new phase in the temperature range of 130–50K, where two independent CDWs coexist. These waves are incommensurate and commensurate CDWs with longitudinal wave vectors and , respectively. By lowering the temperature, intensity of the incommensurate CDW was decreased, while that of the commensurate CDW was increased. Below 50K, the incommensurate CDW was completely diminished. Based on the concept of discommensuration, we suggested the dislocation configuration from the intensity of the two CDWs. [Copyright &y& Elsevier]

We have fabricated a light-emitting diode from horse-heart cytochrome c and measured the electro-luminescence (EL) spectra. The spectra exhibit broad peaks around 530 and 690 nm, and a weak shoulder around 410 nm. The EL spectra are completely different from the photo-luminescence spectra previously reported. The appearance of the 690 nm emission band suggests the charge-transfer between the iron and the axial methionine ligand plays a crucial role in the electrical conduction in the cytochrome c film. [Copyright &y& Elsevier]

The Lifshitz transition, a change in Fermi surface topology, is likely to greatly influence exotic correlated phenomena in solids, such as high-temperature superconductivity and complex magnetism. However, since the observation of Fermi surfaces is generally difficult in the strongly correlated systems, a direct link between the Lifshitz transition and quantum phenomena has been elusive so far. Here, we report a marked impact of the pressure-induced Lifshitz transition on thermoelectric performance for SnSe, a promising thermoelectric material without a strong electron correlation. By applying pressure up to 1.6 GPa, we have observed a large enhancement of the thermoelectric power factor by more than 100% over a wide temperature range (10-300 K). Furthermore, the high carrier mobility enables the detection of quantum oscillations of resistivity, revealing the emergence of new Fermi pockets at ~0.86 GPa. The observed thermoelectric properties linked to the multivalley band structure are quantitatively reproduced by first-principles calculations, providing novel insight into designing the SnSe-related materials for potential valleytronic as well as thermoelectric applications. [ABSTRACT FROM AUTHOR]

We observed all-in type Nb tetrahedral displacement in nonmagnetic pyrochlore niobates A2Nb2O7 (A = Nd0.5Ca0.5 and Y0.5Ca0.5) through the analysis of the neutron pair distribution function and the extended x-ray absorption function spectroscopy. The all-in type Nb tetrahedral displacement, which has the character of a charge singlet state, is driven by the formation of the bonding orbital. The diffuse scattering in the x-ray diffraction, which has the resonant component in the Nb L3 edge, indicates that the all-in type Nb tetrahedral displacement has the periodicity with its short-range correlation. [ABSTRACT FROM AUTHOR]

The infrared reflectance spectra of α-ET2KHg(SCN)4 in applied magnetic fields up to 9.8 T are reported. A dip structure appears in the reflectance spectra around 1000 cm−1 below 10 K at B=0 T. This structure is associated with the density-wave formation in this salt. Under a magnetic field above 4 T, this dip structure disappears. A phase transition at a low magnetic field less than 4 T is suggested. [Copyright &y& Elsevier]

Abstract: Magnetic torque measurements of TPP[Fe(Pc)Br2]2 are reported. The torque curves for the magnetic field rotated within the ac plane exhibit a two-fold symmetry. The temperature dependences of the torque amplitudes divided by the square of the field strength (τφ =45/B 2) exhibit a drastic field dependence below 12K. This field dependence is attributable to the fluctuation in the spontaneous magnetization that appears below 4.5K. The torque curves for the field rotated within the ab plane exhibit four-fold symmetry. The curves are sinusoidal above 18K and exhibit saw-toothed shapes below ∼12K and complicated shapes below 8K. The complicated shapes suggest that both d-electrons and π-electrons form a magnetic order below 8K. [Copyright &y& Elsevier]