Efficient broadband infrared (IR) light-emitting diodes (LEDs) are needed for emerging applications that exploit near-IR spectroscopy, ranging from hand-held electronics to medicine. Here we report ...broadband IR luminescence, cooperatively originating from Eu
and Tb
dopants in CaS. This peculiar emission overlaps with the red Eu
emission, ranges up to 1200 nm (full-width-at-half-maximum of 195 nm) and is efficiently excited with visible light. Experimental evidence for metal-to-metal charge transfer (MMCT) luminescence is collected, comprising data from luminescence spectroscopy, microscopy and X-ray spectroscopy. State-of-the-art multiconfigurational ab initio calculations attribute the IR emission to the radiative decay of a metastable MMCT state of a Eu
-Tb
pair. The calculations explain why no MMCT emission is found in the similar compound SrS:Eu,Tb and are used to anticipate how to fine-tune the characteristics of the MMCT luminescence. Finally, a near-IR LED for versatile spectroscopic use is manufactured based on the MMCT emission.
Variations in percent mammographic density (PMD) reflect variations in the amounts of collagen and number of epithelial and non-epithelial cells in the breast. Extensive PMD is associated with a ...markedly increased risk of invasive breast cancer. The PMD phenotype is important in the context of breast cancer prevention because extensive PMD is common in the population, is strongly associated with risk of the disease, and, unlike most breast cancer risk factors, can be changed. Work now in progress makes it likely that measurement of PMD will be improved in the near future and that understanding of the genetics and biological basis of the association of PMD with breast cancer risk will also improve. Future prospects for the application of PMD include mammographic screening, risk prediction in individuals, breast cancer prevention research, and clinical decision making.
As International Organization commemorates its seventy-fifth anniversary, the Liberal International Order (LIO) that authors in this journal have long analyzed is under challenge, perhaps as never ...before. The articles in this issue explore the nature of these challenges by examining how the Westphalian order and the LIO have co-constituted one another over time; how both political and economic dynamics internal to the LIO threaten its core aspects; and how external threats combine with these internal dynamics to render the LIO more fragile than ever before. This introduction begins by defining and clarifying what is “liberal,” “international,” and “orderly” about the LIO. It then discusses some central challenges to the LIO, illustrated by the contributors to this issue as well as other sources. Finally, we reflect on the analytical lessons we have learned—or should learn—as the study of the LIO, represented by scholarship in International Organization, has sometimes overlooked or marginalized dynamics that now appear central to the functioning, and dysfunction, of the order itself.
Inspired by their excellent thermal stability and strong fatigue resistance, inorganic photochromic materials have been highlighted as promising candidates in various photonic applications ranging ...from photoswitches, anti‐counterfeiting, and encryption to information storage. However, the lack of suitable inorganic materials with both fast photoresponse and strong coloration contrast heavily restricts their applications. Herein, a new strategy is proposed to achieve high photochromic performance via constructing deep‐lying traps in ferroelectric ceramics. The obtained K0.5Na0.5NbO3‐Eu (KNN‐Eu) ceramic exhibits a reversible yellow–gray color change with high fatigue resistance upon alternating illumination (420 nm) and thermal stimulus (450 °C). A fast response time of around 1 s and a large reflectivity difference of 39.2% between the colored and bleached states are simultaneously achieved in KNN‐Eu ceramic, which is by far the best performance ever reported in inorganic photochromic materials. Benefiting from these excellent properties, KNN‐Eu is the first ferroelectric photochromic ceramic to support an instant and hand‐(re)writable information display. The enhanced photochromic performance is expected to facilitate the application of photochromic materials in numerous optical devices and provides a significant guidance to design other inorganic photochromic materials.
Inorganic photochromic materials are promising candidates in applications ranging from photoswitches, anti‐counterfeiting, and encryption to information storage. High photochromic performance is achieved via constructing deep‐lying traps in ferroelectrics. The K0.5Na0.5NbO3‐Eu (KNN‐Eu) ceramic exhibits a fast and reversible yellow–gray color change with excellent contrast upon alternating illumination and thermal bleaching. KNN‐Eu ceramic, therefore, supports an instant and hand‐(re)writable information display.
Modern international interactions are structured by institutions of global governance,
both formal and informal. Most of these institutions are encompassed by the liberal international order. Like ...domestic institutions, these international institutions are challenged
by the prevalence and depth of disinformation. The demand for disinformation, in turn,
has been fed by the order’s lack of attention to growing domestic economic inequality.
Disinformation and inequality thus present twin challenges to global governance.
This innovative study shows that multilateral sanctions are coercive in their pressure on their target and in their origin: the sanctions themselves frequently result from coercive policies, with one ...state attempting to coerce others through persuasion, threats, and promises. To analyze this process, Lisa Martin uses a novel methodology combining game-theoretic models, statistical analysis, and case studies. She emphasizes that credible commitments gain international cooperation, and concludes that the involvement of international institutions and the willingness of the main "sender" to bear heavy costs are the central factors influencing the sanction's credibility.
IMPORTANCE When men are depressed they may experience symptoms that are different than what is included in the current diagnostic criteria. OBJECTIVE To explore whether sex disparities in depression ...rates disappear when alternative symptoms are considered in the place of, or in addition to, more conventional depression symptoms. DESIGN, SETTING, PARTICIPANTS, AND MAIN OUTCOMES AND MEASURES Using data from the National Comorbidity Survey Replication, a nationally represented mental health survey, we evaluated sex differences in symptom endorsement in 2 new scales that included alternative depression symptoms. We analyzed sex differences in symptom endorsement using 2-sided, design-based, .05-level t tests and multivariate logistic regression to identify predictors of depression. RESULTS Men reported higher rates of anger attacks/aggression, substance abuse, and risk taking compared with women. Analyses using the scale that included alternative, male-type symptoms of depression found that a higher proportion of men (26.3%) than women (21.9%) (P = .007) met criteria for depression. Analyses using the scale that included alternative and traditional depression symptoms found that men and women met criteria for depression in equal proportions: 30.6% of men and 33.3% of women (P = .57). CONCLUSIONS AND RELEVANCE When alternative and traditional symptoms are combined, sex disparities in the prevalence of depression are eliminated. Further study is needed to clarify which symptoms truly describe men’s experiences of depression.
The performance of impurity doped luminescent materials, or phosphors, depends on the composition and crystallinity of the host compound, as well as on the distribution and valence state of the ...dopant ions. This is particularly true for persistent phosphors, where both luminescence centers and charge trapping defects are required. Here we show that splitting the synthesis procedure in two separate steps offers a simple way to obtain efficient persistent phosphors which are superior to phosphors prepared
via
a conventional solid state synthesis using a single step. The storage capacity of the persistent phosphor benefits from using a microwave assisted solid state synthesis (MASS) to achieve superior compositional homogeneity, followed by a short heat treatment in a reducing atmosphere to reduce the activators. In this work, the approach is demonstrated for the efficient blue-emitting Eu
2+
,Dy
3+
co-doped Sr
2
MgSi
2
O
7
persistent phosphor. The enhanced ionic diffusion during the MASS not only improves the homogeneity and dopant distribution, but also allows the phosphor to be obtained in considerably shorter times (
ca.
25 minutes). The storage capacity of the as-obtained phosphors prepared by MASS is slightly higher than those obtained by the conventional solid-state method. Cathodoluminescence (CL) measurements evidenced however the existence of a large fraction of unreduced europium activators. Using a short reducing step at 900 °C, the Eu
3+
emission was almost fully suppressed in CL and as a consequence, the storage capacity of the MASS-obtained material showed a ten fold increase, confirming the benefit of decoupling compositional homogeneity and the dopant reduction step for phosphor synthesis.
Microwave irradiation leads to highly homogeneous emitting sites, and large storage capacity in persistent luminescence materials after the reducing step.
Studying the structural environment of the V
IV
ions doped in the metal-organic framework (MOF) DUT-5(Al) ((Al
III
OH)BPDC) with electron paramagnetic resonance (EPR) reveals four different ...vanadium-related spectral components. The spin-Hamiltonian parameters are derived by analysis of X-, Q- and W-band powder EPR spectra. Complementary Q-band Electron Nuclear DOuble Resonance (ENDOR) experiments, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX), X-Ray Diffraction (XRD) and Fourier Transform InfraRed (FTIR) measurements are performed to investigate the origin of these spectral components. Two spectral components with well resolved
51
V hyperfine structure are visible, one corresponding to V
IV
&z.dbd;O substitution in a large (or open) pore and one to a narrow (or closed) pore variant of this MOF. Furthermore, a broad structureless Lorentzian line assigned to interacting vanadyl centers in each other's close neighborhood grows with increasing V-concentration. The last spectral component is best visible at low V-concentrations. We tentatively attribute it to (V
IV
&z.dbd;O)
2+
linked with DMF or dimethylamine in the pores of the MOF. Simulations using these four spectral components convincingly reproduce the experimental spectra and allow to estimate the contribution of each vanadyl species as a function of V-concentration.
EPR spectra of V-doped DUT-5(Al) reveal four types of paramagnetic dopant species. Spin-Hamiltonian analysis and spectrum decomposition as function of V-content are supplemented with structural information from other spectroscopic techniques.
Quantum dots are ideally suited for color conversion in light emitting diodes owing to their spectral tunability, high conversion efficiency and narrow emission bands. These properties are ...particularly important for display backlights; the highly saturated colors generated by quantum dots justify their higher production cost. Here, we demonstrate the benefits of a hybrid remote phosphor approach that combines a green-emitting europium-doped phosphor with red-emitting CdSe/CdS core/shell quantum dots. Different stacking geometries, including mixed and separate layers of both materials, are studied at the macroscopic and microscopic levels to identify the configuration that achieves maximum device efficiency while minimizing material usage. The influence of reabsorption, optical outcoupling and refractive index-matching between the layers is evaluated in detail with respect to device efficiency and cost. From the findings of this study, general guidelines are derived to optimize both the cost and efficiency of CdSe/CdS and other (potentially cadmium-free) quantum dot systems. When reabsorption of the green and/or red emission is significant compared to the absorption strength for the blue emission of the pumping light emitting diode, the hybrid remote phosphor approach becomes beneficial.
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