Luminescent surfaces with tailored angular emission for compact dark-field imaging devices

Dark-field microscopy is a standard imaging technique widely employed in biology that provides high image contrast for a broad range of unstained specimens1. Unlike bright-field microscopy, it accentuates high spatial frequencies and can therefore be used to emphasize and resolve small features. However, the use of dark-field microscopy for reliable analysis of blood cells, bacteria, algae and other marine organisms often requires specialized, bulky microscope systems, as well as expensive additional components, such as dark-field-compatible objectives or condensers2,3. Here, we propose to simplify and downsize dark-field microscopy equipment by generating the high-angle illumination cone required for dark-field microscopy directly within the sample substrate. We introduce a luminescent photonic substrate with a controlled angular emission profile and demonstrate its ability to generate high-contrast dark-field images of micrometre-sized living organisms using standard optical microscopy equipment. This new type of substrate forms the basis for miniaturized lab-on-chip dark-field imaging devices that are compatible with simple and compact light microscopes

Strongly Enhanced Photovoltaic Performance and Defect Physics of Air-Stable Bismuth Oxyiodide (BiOI)

Bismuth-based compounds have recently gained increasing attention as potentially nontoxic and defect-tolerant solar absorbers. However, many of the new materials recently investigated show limited photovoltaic performance. Herein, one such compound is explored in detail through theory and experiment: bismuth oxyiodide (BiOI). BiOI thin films are grown by chemical vapor transport and found to maintain the same tetragonal phase in ambient air for at least 197 d. The computations suggest BiOI to be tolerant to antisite and vacancy defects. All-inorganic solar cells (ITO|NiO$_x$|BiOI|ZnO|Al) with negligible hysteresis and up to 80% external quantum efficiency under select monochromatic excitation are demonstrated. The short-circuit current densities and power conversion efficiencies under AM 1.5G illumination are nearly double those of previously reported BiOI solar cells, as well as other bismuth halide and chalcohalide photovoltaics recently explored by many groups. Through a detailed loss analysis using optical characterization, photoemission spectroscopy, and device modeling, direction for future improvements in efficiency is provided. This work demonstrates that BiOI, previously considered to be a poor photocatalyst, is promising for photovoltaics.R.L.Z.H. thanks Magdalene College, Cambridge. L.C.L. and J.L.M.-D. thank the EPRSC Centre for Doctoral Training: New and Sustainable Photovoltaics, and the Cambridge Winton Programme for the Physics of Sustainability for funding. T.N.H. thanks the Cambridge Graphene Centre, funded by the EPSRC. K.H.L.Z. was supported by the Herschel Smith fellowship. The U.S.-based theory and synthesis portions of this work were supported primarily as part of the Center for Next Generation Materials by Design (CNGMD), an Energy Frontier Research Center funded by the DOE Office of Science, Basic Energy Sciences under Contract No. DE-AC36-08GO28308. The MIT-based characterization portion of this work was supported primarily through a TOTAL SA research grant funded through MITei, as well as a SusChem grant funded by the National Science Foundation (No. CBET-1605495). The TCSPC work was supported as part of the Center for Excitonics, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0001088 (MIT). The computations were performed using resources sponsored by the Department of Energy’s Office of Energy Efficiency and Renewable Energy and located at the NREL. The authors also acknowledge the MRSEC Shared Experimental Facilities at MIT, supported by the National Science Foundation (No. DMF-08019762)

Design Considerations for Tumor-Targeted Nanoparticles

Inorganic/organic hybrid nanoparticles are potentially useful in biomedicine, but to avoid non-specific background fluorescence and long-term toxicity, they need to be cleared from the body within a reasonable timescale1. Previously, we have shown that rigid spherical nanoparticles such as quantum dots can be cleared by the kidneys if they have a hydrodynamic diameter of approximately 5.5 nm and a zwitterionic surface charge2. Here, we show that quantum dots functionalized with high-affinity small-molecule ligands that target tumours can also be cleared by the kidneys if their hydrodynamic diameter is less than this value, which sets an upper limit of 5–10 ligands per quantum dot for renal clearance. Animal models of prostate cancer and melanoma show receptor-specific imaging and renal clearance within 4 h post-injection. This study suggests a set of design rules for the clinical translation of targeted nanoparticles that can be eliminated through the kidneys.National Science Foundation (U.S.) (NSF-0070319)National Institutes of Health (U.S.) (NIH GM68762)National Institutes of Health (U.S.) (NIH grant no. R33-EB-000673)National Institutes of Health (U.S.) ( NIH grant no. R01-CA-115296)National Institutes of Health (U.S.) (MIT-Harvard NanoMedical Consortium (1U54-CA119349, a Center of Cancer Nanotechnology Excellence))Bank of AmericaMedical Foundation, inc. (Charles A. King Trust Postdoctoral Research Fellowship Program)cance

Постать Тараса Шевченка в рецепції Ліни Костенко

У статті розглядається поетика творення Ліною Костенко образу Кобзаря крізь призму власного "я", через пережиті відчуття поета-шістдесятника, що своєю проекцією нагадують душевні терзання великого поета.В статье рассмотрена поэтика создания Линой Костенко образа Тараса Шевченко сквозь призму собственного "я", через пережитые ощущения поэта-шестидесятника, своей проекцией напоминающие душевные терзания великого поэта.The article deals with the problem of the poetics creation by Lina Kostenko Taras Shevchenko’ image through a prism her own mind, through sensations of the poet-sixtier, by the projection reminding sincere torments the great poet is considered

Superradiant emission from self-assembled light emitters: From molecules to quantum dots

Copyright © The Author(s), 2020, published on behalf of Materials Research Society by Cambridge University Press. Colloidal synthesis methods and ultrahigh-vacuum molecular beam epitaxy can tailor semiconductor-based nanoscale single emitters-quantum dots-As the building blocks for classical optoelectronic devices, such as lasers, light-emitting devices, and display technologies. These novel light sources have a basic resemblance of luminescent organic molecules, individually and in the aggregated forms. Highly ordered superstructures of quantum dots, obtained via scalable bottom-up self-Assembly, exhibit diverse collective phenomena, such as band-like charge transport or superradiant emission. Superradiance emerges from coherent coupling of several emitters via a common radiation field resulting in a single giant dipole leading to short (sub-nanosecond) and intense (proportional to the squared number of coupled emitters) bursts of light. In this article, we review the basic principles and progress in the development of superradiant emitters with organic molecules and inorganic quantum dots, in view of their integration into classical and novel quantum light sources

Increasing the penetration depth of temporal focusing multiphoton microscopy for neurobiological applications.

The first ever demonstration of temporal focusing with Short Wave InfraRed (SWIR) excitation and emission is demonstrated, achieving a penetration depth of 500µm in brain tissue. This is substantially deeper than the highest previously-reported values for temporal focusing imaging in brain tissue, and demonstrates the value of these optimized wavelengths for neurobiological applications

Phosphine oxide polymer for water-soluble nanoparticles

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IN-SITU ENCAPSULATION OF QUANTUM DOTS INTO POLYMER MICROSPHERES

We have incorporated fluorescent quantum dots (QDs) into polystyrene microspheres using functionalized oligomeric phosphine (OP) ligands. We find that a uniform distribution of quantum dots is loaded inside each polymer bead. Some local close-packing of quantum dots in the beads is attributed to the self-polymerization of the functionalized ligands. The presence of quantum dots disturbs the nucleation and growth processes during the formation of polymer microspheres and results in a wider size distribution of the quantum dot-embedded polystyrene beads than for the control without dots. The change in quantum efficiency of the quantum dots before (similar to 20%) and after (12%) loading into the beads substantiates the protection of oligomeric phosphine ligands yet indicates that the properties of these quantum dots are still affected during processing.X11124137sciescopu