A facile approach for preparation of photoluminescent (PL) carbon dots (CDs) is reported. The three resulting CDs emit bright and stable red, green and blue (RGB) colors of luminescence, under a single ultraviolet-light excitation. Alterations of PL emission of these CDs are tentatively proposed to result from the difference in their particle size and nitrogen content. Interestingly, up-conversion (UC)PL of these CDs is also observed. Moreover, flexible full-color emissive PVA films can be achieved through mixing two or three CDs in the appropriate ratios. These CDs also show low cytotoxicity and excellent cellular imaging capability. The facile preparation and unique optical features make these CDs potentially useful in numerous applications such as light-emitting diodes, full-color displays, and multiplexed (UC)PL bioimaging.

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Alta Devices, Inc. has previously reported on singlejunction thin-film GaAs photovoltaic devices on flexible substrates with efficiencies up to 28.8% under AM1.5G solar illumination at 1-sun intensity. Here, we show that the same technology platform can be extended to tandem devices that are capable of even higher efficiencies: so far up to 30.8%. Specifically, here, we report on a lattice-matched, series-connected, two-junction device with InGaP as the light-absorbing material of the top cell and GaAs as the absorber in the bottom cell. The material is grown by metallorganic chemical vapor deposition, and then, the device is lifted off by the epitaxial liftoff (ELO) process, as previously reported. This demonstrates that ELO is not only capable of record-setting single-junction performance but capable of achieving world-class efficiency with a multijunction architecture as well.

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Performance analysis is of great significance to increase the operational efficiency of healthcare organizations. Healthcare performance is influenced by numerous indicators, but it is unrealistic for administrators to improve all of them due to the restriction of resources. To solve this problem, we integrated double hierarchy hesitant fuzzy linguistic term sets (DHHFLTSs) with the decision-making trial and evaluation laboratory (DEMATEL) and proposed a DHHFL– DEMATEL method to identify key performance indicators (KPIs) in healthcare management. For the developed approach, the judgments of experts on the inter-relationships among indicators were represented by DHHFLTSs, and a novel combination weighting approach was proposed to obtain experts’ weights in line with hesitant degree and consensus degree. Then, the normal DEMATEL method was extended and used for examining the cause and effect relationships between indicators; the technique for the order of preference by similarity to the ideal solution (TOPSIS) method was utilized to generate the ranking of performance indicators. Finally, the feasibility and effectiveness of the proposed DHHFL–DEMATEL approach were illustrated by a practical example in a rehabilitation hospital.

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generated on the anode surface breaks fragilely, bringing about further electrolyte decomposition and causing low coulombic efficiency (CE) and rapid capacity fade. [4] For decades, extensive endeavors have been made to overcome these issues by developing functional electrolytes, [5][6][7] constructing artificial SEI films, [8][9][10][11] and engineering well-designed host materials. [12][13][14][15][16][17] Among various strategies, the host materials have gained considerable interest because they are effective in reducing the real current density and accommodating large volume changes during Li plating/stripping processes. For instance, Guo et al. [15,16] reported porous carbon nanofibers as fascinating 3D frameworks for stable LMA. Unfortunately, the poor affinity for Li + makes it difficult for the conventional hosts to regulate the Li + concentration near the electrode/electrolyte interface, leading to unsatisfactory cycle life and rate capability.Recently, hosts coupled with nitrogenor oxygen-containing polar functional groups, possessing high Li + anchoring ability, have become a new trend. [18][19][20][21][22] For example, Wang et al. [22] reported N-doped hollow porous carbon spheres (N-HPCSs) fabricated by a carbonization process of a nitrogen resorcinol-formaldehyde coating layer on a SiO 2 template. The N-HPCSs had good lithiophilicity and enabled preferential homogenous deposition of Li inside the spherical cavities owing to high N doping content and porosity. As a consequence, it exhibited a 98.6% CE for more than 270 cycles at 1 mAh cm −2 . When matched with the S cathode as full cells, N-HPCSs@Li displayed a reversible capacity of 907 mAh g −1 (capacity retention: 80.1%) after 400 cycles at 1 C. More recently, it has been found that Li metal can be preferentially deposited on nanoseeds (Au, Ag, Zn, and Mg) because of their appreciable solubility in Li, attaining ultralow or zero overpotential of nucleation. [23] Subsequently, these metals or metal-Li alloys were introduced into the cavities of hosts to further improve the electrochemical properties of LMA. [24][25][26][27] For example, Qiu et al. [27] reported a 3D Mg x Li y /LiF-Li-rGO composite fabricated by a combined process based on vacuum filtration and meltdiffusion. At a current density of 1 mA cm −2 , the symmetric cells with the anode exhibited a small stable hysteresis voltage Uncontrolled lithium dendrite growth and dramatic volume change during cycling have long been severely impeding the practical applications of Li metal as the ultimate anode. In this work, ultrathin MgF 2 nanosheets encapsulated inside nitrogen-doped graphene-like hollow nanospheres (MgF 2 NSs@NGHSs) are ingeniously fabricated to address these problems by a perfect combination of atomic layer deposition and chemical vapor deposition. The uniform and continuous Li-Mg solid-solution inner layer formed by the MgF 2 nanosheets can reduce the nucleation overpotential and induce selective deposition of Li into the cavities of the NGHSs. Furthermore, the Li deposition beh...