bluuebunny/crossref_metadata_2025_split huggingface dataset:
Shorter distances between papers over time are due to more cross-field references and increased citation rate to higher-impact papers
Authors: Varga Attila 
Published: October 2019

Significance
The constantly expanding volume of scientific research engenders specialization, which narrows the focus of research fields. Does this pattern of scientific growth prevent information from circulating between fields? Does motivation to explore new problems and combine innovations across domains counteract this process? This analysis, based on the Science Citation Index, shows that the distances in citation networks decrease from 1950 to 2018. This provides evidence that the sciences diffuse information more easily over time. The shortened distances are due to more dispersed citation activity between fields and growing centralization of citations. Despite these changes, the clustering of citations did not decrease. Cocitations are slightly more embedded over time, which suggests that cross-field ties create their own field boundaries.
TROPOMI reveals dry-season increase of solar-induced chlorophyll fluorescence in the Amazon forest
Authors: Doughty Russell , Köhler Philipp , Frankenberg Christian , Magney Troy S. , Xiao Xiangming , Qin Yuanwei , Wu Xiaocui , Moore Berrien 
Published: October 2019

Significance
The Amazon is the largest terrestrial contributor to global atmospheric carbon fluxes, but it has been debated whether photosynthesis in the Amazonian forest increases during the dry season. We now report new evidence that there is a dry-season increase in photosynthesis in the Amazon rainforest, using observations of solar-induced chlorophyll fluorescence from the Tropospheric Monitoring Instrument (TROPOMI), which has been shown to be a promising proxy of photosynthesis. The new findings point the way toward future research that addresses the implications of Amazonian seasonality on the global carbon cycle.
Carrier localization in perovskite nickelates from oxygen vacancies
Authors: Kotiuga Michele , Zhang Zhen , Li Jiarui , Rodolakis Fanny , Zhou Hua , Sutarto Ronny , He Feizhou , Wang Qi , Sun Yifei , Wang Ying , Aghamiri Neda Alsadat , Hancock Steven Bennett , Rokhinson Leonid P. , Landau David P. , Abate Yohannes , Freeland John W. , Comin Riccardo , Ramanathan Shriram , Rabe Karin M. 
Published: October 2019

Significance
Oxygen vacancies and their associated electrons, ubiquitous in oxide materials, can lead to emergent phenomena. Control of these vacancies allows the manipulation and exploitation of such properties. Using an ultralow oxygen partial pressure environment, we are able to systematically control the oxygen vacancy concentration in thin films of rare-earth nickelates. We find that oxygen vacancies lead to strong carrier localization arising from Ni valence reduction to 2+, resulting in an increase of room-temperature electrical resistivity by several orders of magnitude while maintaining the perovskite structure throughout. The oxygen vacancies can be redistributed by electric fields, leading to analog resistance behavior.
Exquisite sensitivity of adrenocortical carcinomas to induction of ferroptosis
Authors: Belavgeni Alexia , Bornstein Stefan R. , von Mässenhausen Anne , Tonnus Wulf , Stumpf Julian , Meyer Claudia , Othmar Evelyn , Latk Markus , Kanczkowski Waldemar , Kroiss Matthias , Hantel Constanze , Hugo Christian , Fassnacht Martin , Ziegler Christian G. , Schally Andrew V. , Krone Nils P. , Linkermann Andreas 
Published: October 2019

Significance
The currently used treatment regimen for the cancers of the adrenal cortex involves mitotane, a nonspecific derivative of the pesticide DDT (1,1-(dichlorobiphenyl)-2,2-dichloroethane), which has an unclear mechanism of action. Our studies in cell culture and genetic analysis of public databases demonstrate that human adrenocortical carcinomas (ACCs) are remarkably sensitive to a recently defined cell death pathway referred to as ferroptosis, indicating that induction of ferroptosis could be a promising treatment approach for ACCs. However, mitotane does not induce ferroptosis. Given the untoward side effect profile of mitotane, we suggest that ferroptosis-inducing agents may represent a more specific, more potent, and less toxic approach to treatment for patients with ACC than mitotane.
4D electron microscopy of T cell activation
Authors: Lu Yue , Yoo Byung-Kuk , Ng Alphonsus H. C. , Kim Jungwoo , Yeom Sinchul , Tang Jau , Lin Milo M. , Zewail Ahmed H. , Heath James R. 
Published: October 2019

SignificancePhoton-induced near-field electron microscopy (PINEM) enables the visualization of nanoscale structures and interfaces with enhanced contrast due to the energy gain of electrons from light-excited evanescent electromagnetic fields. Here we optimized a PINEM approach to directly image and quantify these fields at the surface of T cells as a function of various stimulation conditions. We found that while PINEM is sensitive to multiple biophysical changes associated with T cell activation, it strongly correlates with binding of specific antigen major histocompatibility complex, even without accompanying functional T cell activation. Our results suggest that PINEM can find use as a cellular imaging tool, with exquisite surface selectivity and high sensitivity to structural changes on the length scale of cell surface protein aggregates.
Effect of Indium doping on the superconductivity of layered oxychalcogenide La2O2Bi3Ag1-xInxS6
Authors: Jha Rajveer , Goto Yosuke , Matsuda Tatsuma D , Aoki Yuji , Mizuguchi Yoshikazu 
Published: October 2019

Abstract
We report on the substitution effect of Indium (In) at the Ag site of layered oxychalcogenide La2O2Bi3Ag1−x
In
x
S6. The T
c decreases with increasing In concentration. A hump in the normal state resistivity at an anomaly temperature (T*) near 180 K was observed for all the samples. The anomaly in the resistivity at T* is indicating the possible occurrence of a charge-density-wave (CDW) transition. The T* does not markedly change by In doping. The x dependence of Seebeck coefficient suggests that carrier concentration does not change by In doping. The EDX analysis indicates small amount of Bi deficiency, which suggests that the Bi site is slightly substituted by In. The CDW transition is robust against the In substitution at Ag site, while T
c is decreasing due to the Bi site substitution by In. On the basis of those analyses, we propose that the suppression of superconductivity in the In-doped La2O2Bi3Ag1-x
In
x
S6 system is caused by negative in-plane chemical pressure effect and partial substitution of In for the inplane Bi site.
Evaluation of Layer Thickness Dependence of Critical Current Density using Longitudinal Magnetic Field Effect in Superconducting Coated Conductors
Authors: Yonenaka T , Otabe E S , Vyatkin V , Lee S , Akune T , Nishizaki T 
Published: October 2019

Abstract
When the critical current density J
c for a superconductor is constant, the critical current I
c increases in proportion to the superconducting cross-sectional area. However, in the case of a superconducting coated conductor, when the thickness of the superconducting layer exceeds about 2 μm, there is no further increase in I
c. This is because J
c decreases due to the structural degradation of the superconducting layer. In this study, J
c for samples with superconducting layers of different thicknesses was measured using the longitudinal magnetic field effect in order to investigate the optimum layer thickness for maximizing I
c. Differences in the J
c characteristics due to the layer thickness appeared more clearly under a longitudinal magnetic field than a transverse magnetic field. This was particularly true at low temperatures, and the optimum layer thickness was found to be approximately 1 μm.
TDGL Simulation on Angular Dependence of Critical Current Density in Superconductors with Columnar Defects
Authors: Yonezuka Rina , Hamada Yusei , Kamiji Kazunori , Tanimura Kenta , Yoshihara Takaki , Otabe Edmund Soji , Mawatari Yasunori , Matsuno Tetsuya 
Published: October 2019

Abstract
We numerically solved the three dimensional time-dependent Ginzburg-Landau (TDGL) equations to visualize the motion of the quantized magnetic flux lines in the superconductor under the transverse magnetic field B. We investigated the angular dependence of the critical current density J
c in the columnar pins using TDGL equations. As a result of simulations, it was confirmed that J
c decreases as increasing the angle θ between the columnar pins and the quantized magnetic flux lines. In particular at B = 0.4, J
c sharply decreased at θ between 20° and 30°. This result was compared with the calculation result of the overlapped volume between the quantized magnetic flux and the pins. The calculated result by TDGL equations was in good agreement with the calculated result by the overlapped volume. In addition, J
c was calculated using various pins such as the sphere, the columnar and the plane pins. It was found that plane pins are more effective than pins of other shapes. In addition, although it is experimentally difficult to fabricate, J
c of the star-shaped pin was obtained by the TDGL simulations. It was found that the J
c of the star-shaped pin shows the highest performance among all the kinds of configurations for the columnar pins in high magnetic fields.
Relationship between superconductivity and anisotropy in two-dimensional Hubbard model
Authors: Kobayashi Kenji , Yokoyama Hisatoshi 
Published: October 2019

Abstract
In connection with the symmetry-breaking phenomena found in cuprate superconductors, we check whether an anisotropy spontaneously appears or not in strongly correlated electrons that exhibit superconductivity and/or antiferromagnetism. A variational Monte Carlo method is applied to the square-lattice Hubbard model (U/t = 12) with diagonal transfer t′. In the trial wave function used, we introduce band renormalization factors including adjustable parameters for the anisotropy corresponding to the fourfold rotational symmetry breaking. It is confirmed that the anisotropy appears in the overdoped regime, where the Fermi-liquid features are predominant. In the underdoped area, the anisotropy does not appear for t′/t = 0 and +0.3, whereas it possibly appears in the underdoped regime for t′/t = −0.3.
Electronic Structure of Novel Non-centrosymmetric Superconductor Mg2Rh3P
Authors: Hase I , Yanagisawa T , Iyo A , Fujihisa H , Goto Y , Eisaki H , Kawashima K 
Published: October 2019

Abstract
We calculated the electronic structure of a novel non-centrosymmetric superconductor Mg2-xRh3P from first-principles. Stoichiometric Mg2Rh3P shows a pseudogap at the Fermi level. This is consistent with the experimental fact that the stoichiometric sample Mg2Rh3P does not show superconductivity and the Mg-deficient sample Mg19Rh3P shows superconductivity with T
c ∼ 3.6 K. The band dispersion of Mg2Rh3P shows a characteristic band splitting due to the anti-symmetric spin-orbit coupling (ASOC). The magnitude of ASOC of Mg2Rh3P is comparable to Li2Pd3B. We also show that its 5d-counterpart Mg2Ir3P may have quite a large ASOC, and is a good candidate of parity-mixed superconductor likewise Li2Pd3B.
Impurity effects on dx2−y2
-wave superconducting state in strongly correlated Hubbard model
Authors: Sato Ryo , Yokoyama Hisatoshi 
Published: October 2019

Abstract
With cuprate superconductors in mind, we study the effects of point-type impurity potential (V) on a d

x
2−y
2
-wave superconducting (d-SC) state in a strongly correlated squarelattice Hubbard model (U/t = 12) with a diagonal transfer (t′), using a variational Monte Carlo method. At half filling, insulator-to-conductor (filling-control-type Mott) transitions occur at

V
=

V
U

(
±
)

∼
±
U

. The phase realized for

V
<

V
U

(
−
)

is robust d-SC and the charge carriers are holes, whereas for

V
>

V
U

(
+
)

a metallic (or weak d-SC) state appears with charge carriers of electrons. For a partially-filled case where the impurity density is equal to the doping rate, a d-SC-to-insulator transition arises at V ≡ V
M ∼ 4t. In the weak-|V| phases, the impurity effects in the electron distribution are smeared out by the screening effect, whereas in the strong-|V| phases, the electron distribution directly depend on the impurity configurations.
Effects of Sm1+xBa2-xCu3Oy Films with Non-Stoichiometric Composition Fabricated by Combinatorial Pulsed Laser Deposition method on the Superconducting Properties
Authors: Murase G. , Tsuchiya Y. , Ichino Y. , Yoshida Y. 
Published: October 2019

Abstract
Sm1+x
Ba2-x
Cu3O
y
, (Sm-rich) had higher critical current density (J
c) in magnetic fields and higher irreversible fields than stoichiometric SmBa2Cu3O
y
(SmBCO) thin films. In this study, to clarify the features of artificial pinning centers (APCs) doped Sm-rich films, we prepared BaHfO3 (BHO)-doped Sm1+x
Ba2-x
Cu3O
y
films with x = 0.00 ∼ 0.20 using combinatorial pulsed laser deposition (C-PLD) method on a metallic substrate and we evaluate surface morphrogies, crystal orientations and superconducting properties of the films. As a result, when x increased, the terrace width also increased. From the measurement of J
c in magnetic fields, the BHO-doped Sm-rich films showed J
c plateaus around 1 ∼ 3 T. From the angulaer dependence of J
c, the BHO-doped Sm-rich films showed J
c peak where B is parallel to c-axis. From several measurements, we discuss effects of Sm1+x
Ba2-x
Cu3O
y
films with and without BHO on the superconducting properties.
Generation of Uniform Magnetic Field between Face-to-Face HTS Bulk Magnets
Authors: Oka T , Higa K , Tsunoda S , Ogawa J , Fukui S , Inoue N , Miryala M , Murakami M , Yokoyama K , Nakamura T 
Published: October 2019

Abstract
Aiming to develop the compact nuclear magnetic resonance devices, the authors have been developing the uniform magnetic fields in the space between the face-to-face magnetic poles which contain HTS bulk magnets. The authors deformed the original convex shape of the magnetic field distribution to concave by attaching a ferromagnetic iron plate of 20 mm and 100 mm in diameter on one of the pole surfaces. The magnetic field distribution precisely measured along x-axis changed from concave to convex with increasing distance from the magnetic pole surface, which suggested the presence of magnetically flat region. From the results of mapping on the field uniformity data, we have succeeded in obtaining the field uniformity under 500ppm in the space of 4 x 4 x 0.8 mm3 when the magnetic poles emitting concave and convex field distributions were settled face-to-face with various gaps 30-70 mm. This performance exceeded the target value of 1,500ppm which is necessary to detect the NMR signals.
Reduction of Environmental Magnetic Field Noise for Detection of Small Magnetic Contaminants
Authors: Nishikawa Takao , Sakuta Ken 
Published: October 2019

Abstract
When performing high-sensitivity magnetic measurements via a high-sensitivity magnetic sensor such as a SQUID (Superconducting QUantum Interference Device) magnetometer, it is necessary to shield from environmental magnetic noise by employing a magnetic shield box. In general, however, the low frequency of such noise decreases the shielding performance of the magnetic shield box. Hence, the magnetic metallic contaminant signal and the low-frequency ambient magnetic field noise overlap, which makes filtering a challenging task. Therefore, we studied a system that suppresses gradient magnetic noise such as low-frequency environmental noise superimposed on a contaminant signal and commercial power supply noise localized spatially.
Conceptual Study on lighter and more compact transmission cable systems for Hybrid Aircrafts
Authors: Isojima S , Yoshida Y , Amemiya N , Sadakata N , Ohsaki H , Okada M 
Published: October 2019

Abstract
More electrically driven aircrafts with electric propulsion systems are supposed to require 1-40 MW. In order to realize such heavily electrical aircrafts the development of lighter and more compact transmission cable systems is indispensable. We compared metal cables and superconducting cables, and found that DC superconducting cables are lighter and more compact than metal cables at voltages as high as ±6 kV.
Removal of Scale from Feed-water in Thermal Power Plant by Magnetic Separation -Analysis of Oxygenated Treatment Scale-
Authors: Hiramatsu M , Yamamoto J , Akiyama Y , Mishima F , Nishijima S , Okada H , Hirota N , Yamaji T , Matsuura H , Namba S , Sekine T , Kobayashi Y , Seto M 
Published: October 2019

Abstract
One of the reasons of the deterioration of the power generation efficiency of the thermal power generation is the adhesion of the iron scale generated by the corrosion of the pipe to the inner wall of the feed-water system. Focusing on the magnetic property of scale, we studied on the removal of scales in the feed-water system by high gradient magnetic separation (HGMS) using the superconducting magnet. In this study, we targeted the thermal power plants adopting oxygenated treatment (OT). In order to determine the installation site and the magnetic separation condition of the HGMS system, we analyzed the OT scale and then clarified the aggregation/composite states by magnetic separation experiment. It is concluded that low-pressure feed-water heater drain is suitable for installation site of HGMS system. In addition, it was clarified that homogeneous aggregation particles existed in the OT scale.
Energy losses in magnetic contactless bearings on the base of high-Tc superconducting tapes
Authors: Rudnev I A , Podlivaev A I , Osipov M A , Abin D A , Anischenko I V , Pokrovskii S V 
Published: October 2019

Abstract
High-temperature superconducting tapes are very promising for application in rotary magnetic bearings owing to its excellent magnetic and transport properties as well as possibility to easy create magneto-levitation systems of various geometry. One of problem arising in the rotation superconducting bearings is the presence of the energy loss resulting from the magnetization hysteresis due to inhomogeneity of magnetic field from permanent magnets. In this report we present results theoretical studies of rotation losses in the model superconducting bearing based on commercial high temperature superconducting (HTS) tape. The bearing stator has a cylindrical shape and is made of a multilayer HTSC tape. The bearing rotor is made of permanent magnets located at the same radius relative to the axis of rotation. As a result of numerical calculations carried out in the framework of the critical state model, the rotor geometry was established, at which the value of energy losses was minimal.
The consumptive water footprint of the European Union energy sector
Authors: Vanham Davy , Medarac Hrvoje , Schyns Joep F , Hogeboom Rick J , Magagna Davide 
Published: October 2019

Abstract
Energy security for the EU is a priority of the European Commission. Although both blue and green water resources are increasingly scarce, the EU currently does not explicitly account for water resource use in its energy related policies. Here we quantify the freshwater resources required to produce the different energy sources in the EU, by means of the water footprint (WF) concept. We conduct the most geographically detailed consumptive WF assessment for the EU to date, based on the newest spatial databases of energy sources. We calculate that fossil fuels and nuclear energy are moderate water users (136–627 m3/terajoules (m3 TJ–1)). Of the renewable energy sources, wood, reservoir hydropower and first generation biofuels require large water amounts (9114–137 624 m3 TJ–1). The most water efficient are solar, wind, geothermal and run-of-river hydropower (1–117 m3 TJ–1). For the EU territory for the year 2015, our geographically detailed assessment results in a WF of energy production from domestic water resources of 198 km3, or 1068 litres per person per day. The WF of energy consumption is larger as the EU is to a high level dependent on imports for its energy supply, amounting to 242 km3 per year, or 1301 litres per person per day. The WF of energy production within the 281 EU statistical NUTS-2 (Nomenclature of Territorial Units for Statistics) regions shows spatially heterogeneous values. Different energy sources produced and consumed in the EU contribute to and are produced under average annual and monthly blue water stress and green water scarcity. The amount of production under WS is especially high during summer months. Imported energy sources are also partly produced under WS, revealing risks to EU energy security due to externalisation. For the EU, to decarbonise and increase the share of renewables of its energy supply, it needs to formulate policies that take the water use of energy sources into account. In doing so, the spatial and temporal characteristics of water use and water stress should particularly be considered.
A monitoring and prediction system for compound dry and hot events
Authors: Hao Zengchao , Hao Fanghua , Xia Youlong , Singh Vijay P , Zhang Xuan 
Published: October 2019

Abstract
Compound dry and hot events (i.e. concurrent or consecutive occurrences of dry and hot events), which may cause larger impacts than those caused by extreme events occurring in isolation, have attracted wide attention in recent decades. Increased occurrences of compound dry and hot events in different regions around the globe highlight the importance of improved understanding and modeling of these events so that they can be tracked and predicted ahead of time. In this study, a monitoring and prediction system of compound dry and hot events at the global scale is introduced. The monitoring component consists of two indicators (standardized compound event indicator and a binary variable) that incorporate both dry and hot conditions for characterizing the severity and occurrence. The two indicators are shown to perform well in depicting compound dry and hot events during June–July–August 2010 in western Russia. The prediction component consists of two statistical models, including a conditional distribution model and a logistic regression model, for predicting compound dry and hot events based on El Niño–Southern Oscillation, which is shown to significantly affect compound events of several regions, including northern South America, southern Africa, southeast Asia, and Australia. These models are shown to perform well in predicting compound events in large regions (e.g. northern South America and southern Africa) during December–January–February 2015–2016. This monitoring and prediction system could be useful for providing early warning information of compound dry and hot events.