Formation and Growth of Atomic Scale Seeds of Au Nanoparticle in the Nanospace of an Organic Cage Molecule

Seed-mediated growth has been widely used to synthesize noble metal nanoparticles with controlled size and shape. Although it is becoming possible to directly observe the nucleation process of metal atoms at the single atom level by using transmission electron microscopy (TEM), it is challenging to control the formation and growth of seeds with only a few metal atoms in homogeneous solution systems. This work reports site-selective formation and growth of atomic scale seeds of the Au nanoparticle in a nanospace of an organic cage molecule. We synthesized a cage molecule with amines and phenols, which were found to both capture and reduce Au(III) ions to spontaneously form the atomic scale seeds containing Au(0) in the nanospace. The growth reaction of the atomic scale seeds afforded Au nanoparticles with an average diameter of 2.0±0.2 nm, which is in good agreement with the inner diameter of the cage molecule.

Calving prediction with continuous measurement of subcutaneous tissue glucose concentration in pregnant cows

To reduce losses of dams and calves due to unfortunate events, such as dystocia and freezing to death, identifying the onset of calving and providing necessary assistance are crucial. Prepartum increase in blood glucose concentration is a known indicator to detect labor in pregnant cows. However, some issues, including the need for frequent blood sampling and stress on cows, must be resolved before establishing a method for anticipating calving using changes in blood glucose concentrations. Herein, instead of measuring the blood glucose concentrations, subcutaneous tissue glucose concentration (tGLU) was measured in peripartum primiparous (n = 6) and multiparous (n = 8) cows at 15 min intervals using a wearable sensor. A transient increase in tGLU was observed in the peripartum period, with peak individual concentrations occurring between 2.8 h before and 3.5 h after calving. tGLU in primiparous cows was significantly higher than that in multiparous cows. To account for individual variations in basal tGLU, the maximum relative increase in the 3-h moving average of tGLU (Max MA) was used to predict calving. Cutoff points for Max MA were established by parity, with receiver operating characteristic analysis predicting calving within 24, 18, 12, and 6 h. Except for one multiparous cow that showed an increase in tGLU just before calving, all cows reached at least two cutoff points and calving was predicted successfully. The time interval between reaching the tGLU cutoff points that predicted calving within 12 h and actual calving was 12.3 ± 5.6 h. In conclusion, this study demonstrated the potential role of tGLU as a predictive indicator of calving in cows. Advancements in machine learning-based prediction algorithms and bovine-optimized sensors will help in increasing the accuracy of calving prediction using tGLU.

Thermosensitive visible-light-excited visible-/NIR-luminescent complexes with lanthanide sensitized by the π-electronic system through intramolecular H-bonding

Visible-luminescent lanthanide (LnL) complexes with a highly planar tetradentate ligand were successfully developed for a visible-light solid-state excitation system. L was designed by using two 2-hydroxy-3-(2-pyridinyl)-benzaldehyde molecules bridged by ethylenediamine, which was then coordinated to a series of Ln ions (Ln = Nd, Sm, Eu, Gd, Tb, Dy, and Yb). From the measurement of single-crystal X-ray analysis of EuL, two phenolic O atoms and two imine N atoms in L were coordinated to the Eu ion, and each π-electronic system took coplanar with the edged-pyridine moiety through an intramolecular hydrogen bond. The enol group on the phenolic skeleton changed to the keto form, and the pyridine was protonated. Thus, intramolecular proton transfer occurred in L after the complexation. Other complexes take isostructure. The space group is P-1, and the c-axis shrinks with decreasing temperature without a phase transition in EuL. The yellow color caused by the planar structure of L can sensitize ff emission by visible light, and the luminescence color of each complex depends on central Ln ions. Furthermore, a phosphorescence band also appeared at rt with ff emission in LnL. Drastic temperature dependence of luminescence was clarified quantitatively.

High-power laser experiment forming a supercritical collisionless shock in a magnetized uniform plasma at rest

We present an experimental method to generate quasiperpendicular supercritical magnetized collisionless shocks. In our experiment, ambient nitrogen (N) plasma is at rest and well magnetized, and it has uniform mass density. The plasma is pushed by laser-driven ablation aluminum (Al) plasma. Streaked optical pyrometry and spatially resolved laser collective Thomson scattering clarify structures of plasma density and temperatures, which are compared with one-dimensional particle-in-cell simulations. It is indicated that just after the laser irradiation, the Al plasma is magnetized by a self-generated Biermann battery field, and the plasma slaps the incident N plasma. The compressed external field in the N plasma reflects N ions, leading to counterstreaming magnetized N flows. Namely, we identify the edge of the reflected N ions. Such interacting plasmas form a magnetized collisionless shock.

Incoherent color digital holography with computational coherent superposition for fluorescence imaging [Invited]

We present color fluorescence imaging using an incoherent digital holographic technique in which holographic multiplexing of multiple wavelengths is exploited. Self-interference incoherent digital holography with a single-path in-line configuration and the computational coherent superposition scheme are adopted to obtain color holographic three-dimensional information of self-luminous objects with a monochrome image sensor and no mechanical scanning. We perform not only simultaneous color three-dimensional sensing of multiple self-luminous objects but also color fluorescence imaging of stained biological samples. Color fluorescence imaging with an improved point spread function is also demonstrated experimentally by adopting a Fresnel incoherent correlation holography system.

Two-step phase-shifting interferometry for self-interference digital holography

We propose a phase-shifting interferometry technique using only two in-line phase-shifted self-interference holograms. There is no requirement for additional recording or estimation in the measurement. The proposed technique adopts a mathematical model for self-interference digital holography. The effectiveness of the proposed technique is demonstrated by experiments on incoherent digital holographic microscopy and color-multiplexed fluorescence digital holography with computational coherent superposition. Two-color-multiplexed four-step phase-shifting incoherent digital holography is realized for the first time, to the best of our knowledge, using the proposed technique.

Lanthanide Luminescence Enhancement of Core-Shell Magnetite-SiO2 Nanoparticles Covered with Chain-Structured Helical Eu/Tb Complexes

Oligomeric-brush chains of helical lanthanide (Ln) complexes retain their structural and luminescent behavior after coating onto magnetic nanoparticles (MNPs) consisting of Fe₃O₄ covered with silicate. It is one of the type of bifunctional NPs exhibiting luminescence of Ln and superparamagnetism of Fe₃O₄. In comparison to a simple monolayer of complexes adsorbed on a modified surface, a layer made of luminescent chains allowed us to obtain a more intensive red/green luminescence originating from Eu³⁺/Tb³⁺ ions, and at the same time, no visible increase in particle size (compared to Fe₃O₄@silica particles) was observed. The luminescent properties of the Tb³⁺ complex were altered by MNPs; the decrease of the luminescence was not as large as expected, the excitation spectrum changed significantly, and the average luminescence lifetime was much longer at room temperature. Surprisingly, this phenomenon was not observed at 77 K and also did not occur for the Eu³⁺ complexes. The possibility to stack building blocks in a chain using complexes of different lanthanide ions can be used to design novel multifunctional nanosystems.

Quantum cutting-induced near-infrared luminescence of Yb3+ and Er3+ in a layer structured perovskite film

Quantum cutting is an attractive optical phenomenon where one high-energy photon is converted into two low-energy photons, resulting in photoluminescence quantum yields (PLQYs) above 100%. In this report, we demonstrate a novel approach to enhance the quantum cutting energy transfer from an all-inorganic perovskite (CsPbCl₃) to ytterbium (Yb³⁺) and erbium (Er³⁺) ions as near-infrared (NIR) emitters by using the highly orientated crystalline film. Yb³⁺ ions are fixed in the neighborhood of the CsPbCl₃ lattice by preparing a one-to-one layer arrangement consisting of quasi-2D CsPbCl₃ perovskite and Yb³⁺ layers. The successful preparation of layer arrangements resulted in the highly sensitized luminescence of Yb³⁺ by CsPbCl₃ with NIR PLQYs exceeding 130%, which is attributed to quantum cutting. In addition, Er³⁺ luminescence at 1540 nm is acquired by the co-existence of Er³⁺ with Yb³⁺ in a layer, which is a result of the intralayer metal-to-metal energy transfer from Yb³⁺ activated by CsPbCl₃ via the interlayer quantum cutting process. The PLQY of Er³⁺ luminescence reaches to 12.6%, which is the highest value ever observed for Er³⁺ compounds, resulting from the efficient interlayer quantum cutting process over 100% and the following intralayer resonance metal to metal energy transfer with the efficiency over 80%.

Spearmint Extract Containing Rosmarinic Acid Suppresses Amyloid Fibril Formation of Proteins Associated with Dementia

Neurological dementias such as Alzheimer's disease and Lewy body dementia are thought to be caused in part by the formation and deposition of characteristic insoluble fibrils of polypeptides such as amyloid beta (Aβ), Tau, and/or α-synuclein (αSyn). In this context, it is critical to suppress and remove such aggregates in order to prevent and/or delay the progression of dementia in these ailments. In this report, we investigated the effects of spearmint extract (SME) and rosmarinic acid (RA; the major component of SME) on the amyloid fibril formation reactions of αSyn, Aβ, and Tau proteins in vitro. SME or RA was added to soluble samples of each protein and the formation of fibrils was monitored by thioflavin T (ThioT) binding assays and transmission electron microscopy (TEM). We also evaluated whether preformed amyloid fibrils could be dissolved by the addition of RA. Our results reveal for the first time that SME and RA both suppress amyloid fibril formation, and that RA could disassemble preformed fibrils of αSyn, Aβ, and Tau into non-toxic species. Our results suggest that SME and RA may potentially suppress amyloid fibrils implicated in the progression of Alzheimer's disease and Lewy body dementia in vivo, as well.

Direct detection of circular polarized light in helical 1D perovskite-based photodiode

Detection of circularly polarized light (CPL) has a high potential for development of various optical technologies. Conventional photodetectors require optical polarizers on the device to detect polarized light, and this causes substantial losses of sensitivity and resolution in light detection. Here, we report direct CPL detection by a photodiode using a helical one-dimensional (1D) structure of lead halide perovskites composed of naphthylethylamine-based chiral organic cations. The 1D structure with face-sharing (PbI₆)^4- octahedral chains whose helicity is largely affected by chiral cations shows intense circular dichroism (CD) signals over 3000 mdeg at 395 nm with the highly anisotropy factor (g _CD) of 0.04. This high CD enables photocurrent detection with effective discrimination between left-handed and right-handed CPLs. The CPL detector based on this 1D perovskite achieved the highest polarization discrimination ratio of 25.4, which largely surpasses the direct detecting CPL devices (<4) using chiral plasmonic metamaterials and organic materials.

Surgical options in suprastomal collapse-induced severe airway obstruction

Purpose

A single institutions experience with various surgical options in the treatment of severe suprastomal collapse (SSC).

Methods

The study included 18 tracheostomized children with SSC treated between January 2012 and December 2018. Data included: patient demography, initial airway lesions, comorbidities, indication and age at tracheostomy, prior airway surgery, stomal demography, type of surgery, postoperative management, complications and treatment outcomes.

Results

Four techniques were used to correct SSC. The surgical choice was dependent on stoma demography and associated airway lesions. Excision was done in eight patients and rib cartilage augmentation in five. Three patients had single stage tracheal resection and anastomosis. Two patients received stomal rigidification and temporary placement of Montgomery T tube. Three patients with anterior rib graft augmentation required additional lateral tracheal wall rigidification. Three patients (two with cartilage augmentation, and one with stomal rigidification) developed minimal granulation tissue in the postoperative period. Complete SSC resolution was seen in all except two patients who had a partial response to the treatment. All patients were successful decannulated and are currently asymptomatic.

Conclusion

Decannulation failures may be due to severe suprastomal collapse that could be either unique or associated with obstructing laryngotracheal lesions. Therefore, it is essential to select the most appropriate surgical treatment to obtain overall favorable outcomes.

Electronic supplementary material

The online version of this article (10.1007/s00405-020-06339-3) contains supplementary material, which is available to authorized users.

Aspects of lanthanide complexes for selectivity, intensity and sharpness in luminescence bands from twenty-four praseodymium, europium and gadolinium complexes with differently distorted-hexadentate ligands

We structurally and spectroscopically investigated a series of praseodymium (Pr) complexes with eight ligands that form helicate molecular structures. The mother ligand skeleton (L) has two bipyridine moieties bridged with ethylenediamine. The bridged skeleton of PrL was changed to diamines 1-methyl-ethylenediamine, trimethylenediamine and 2,2'-dimethyl-trimethylenediamine, and the corresponding ligands were designated as L^me, L^pr and L^dmpr, for each Pr in these complexes upon UV-excitation. The luminescence quantum yields of PrL and PrL^pr in the visible and near infrared (NIR) regions indicate that PrL is excited by both the electronic state of the ligand and the ff absorption band, whereas PrL^pr is excited through the ligand. The addition of a methyl group to PrL and PrL^pr has a different effect on the Pr emission intensity with the intensity of PrL^me decreasing more than that of PrL and PrL^dmpr and increasing more than that of PrL^pr. Thus, the coordination of Pr and the increased rigidity of the ligand upon methylation enhance luminescence. The azomethine moieties on L^me, L^pr and L^dmpr were reduced and formed the corresponding PrLH, PrL^meH, PrL^prH and PrL^dmprH complexes. The luminescence of the non-methylated series is due to transitions related to the ¹D₂ level and thus the methylated series luminesces due to high energy levels such as ³P_J arising from the shortened π electronic systems. We also discuss the strong red emission of a series of Eu complexes with eight ligands from the viewpoint of their molecular structures and luminescence efficiencies and evaluate the Judd-Ofelt parameters from the luminescence spectra of Eu complexes.

Cesium Acetate-Induced Interfacial Compositional Change and Graded Band Level in MAPbI3 Perovskite Solar Cells

Compositional engineering and interfacial modifications have played pivotal roles in the accomplishment of high-efficiency perovskite solar cells (PSCs). Different interfaces in the PSCs influence the performance remarkably either by altering the crystallization of the active material or shifting the energy levels or improving the electrical contact. This work reports how a thin layer of cesium acetate on the TiO₂ electron transport layer (ETL) induces generation of a PbI₂-rich methylammonium lead iodide (MAPbI₃) composition at the ETL/MAPbI₃ interface, which downshifts the conduction band level of MAPbI₃ to create an energy level gradient favorable for carrier collection, resulting in higher photocurrent, fill factor, and overall power conversion efficiency.

Chiroptical Spectroscopic Studies on Lanthanide Complexes with Valinamide Derivatives in Solution

Ligands based on 2,2'-bipyridine and valinamide moieties induce circularly polarized luminescence in their europium complexes. Both the R and S enantiomers of the complexes were successfully obtained. Single-crystal X-ray analysis of the racemic crystal confirmed that the ligand is coordinated to the europium ion in a tetradentate fashion. The π-electronic system of the ligand is co-planar with the valinamide moiety, and acts as an efficient photoantenna to sensitize europium luminescence by UV excitation. The luminescence quantum yield (QY) of europium in the valinamide-containing complex was 44 % in acetonitrile. The g_lum value to evaluate the circularly polarized luminescence was relatively high at |0.13| estimated from their magnetic dipole transitions around 593 nm. For comparison, we prepared hexadentate europium complexes in the S- and R-forms derived from two bipyridine moieties linked by ethylenediamines. The determined QYs were 18 % (S) and 16 % (R), and the g_lum value |0.12| for the hexadentate complexes. The photophysical properties of the gadolinium complexes of the ligands were also evaluated.

VOC Over 1.4 V for Amorphous Tin-Oxide-Based Dopant-Free CsPbI2Br Perovskite Solar Cells

CsPbI₂Br perovskite solar cells have attracted much attention because of the rapid development in their efficiency and their great potential as a top cell of tandem solar cells. However, the V_OC outputs observed so far in most cases are far from that desired for a top cell. Up to now, with various kinds of treatments, the reported champion V_OC is only 1.32 V, with a V_OC deficit of 0.60 V. In this work, we found that aging of the SnCl₂ precursor solution for the electron-transporting layer can promote the V_OC of CsPbI₂Br solar cells by employing a dopant-free-polymer hole transport material (HTM) over 1.40 V and efficiency over 15.5% with high reproducibility. With the champion V_OC of 1.43 V, the V_OC deficit was reduced to <0.50 V, which is achieved for the first time. This simple technique of SnCl₂ solution aging forms a uniform and smooth amorphous SnO_x film with pure Sn⁴⁺, elevates the conduction band of SnO_x, and reduces the interfacial gaps and the trap state density of the device, resulting in enhancement in average V_OC from ∼1.2 V in the nonaged case to ∼1.4 V in the aged case. Furthermore, the device using an aged SnCl₂ solution also exhibits a much better long-term stability than that made of the fresh solution. These achievements in dopant/additive-free CsPbI₂Br solar cells can be useful for future research on CsPbI₂Br and tandem solar cells.

Sensitized Yb3+ Luminescence in CsPbCl3 Film for Highly Efficient Near-Infrared Light-Emitting Diodes

Near-infrared (NIR) light emitting diodes (LEDs) with the emission wavelength over 900 nm are useful in a wide range of optical applications. Narrow bandgap NIR emitters have been widely investigated using organic compounds and colloidal quantum dots. However, intrinsically low charge mobility and luminescence efficiency of these materials limit improvement of the external quantum efficiency (EQE) of NIR LEDs, which is far from practical applications. Herein, a highly efficient NIR LED is demonstrated, which is based on an energy transfer from wide bandgap all inorganic perovskite (CsPbCl3) to ytterbium ions (Yb3+) as an NIR emitter doped in the perovskite crystalline film. High mobility of electrically excited carriers in the perovskite crystalline film provides a long carrier diffusion and enhances radiative recombination of an emission center due to minimized charge trapping losses, resulting in high EQE value in LEDs. The NIR emission of Yb3+ at around 1000 nm is found to be sensitized by CsPbCl3 thin film with a photoluminescence quantum yield over 60%. The LED based on Yb3+-doped CsPbCl3 film exhibits a high EQE of 5.9% with a peak wavelength of 984 nm, achieved by high carrier transporting ability and effective sensitized emission property in the solid-film structure.

Photomultiplying Visible Light Detection by Halide Perovskite Nanoparticles Hybridized with an Organo Eu Complex

A molecular layer of an organo europium (Eu) complex was hybridized with the surface of halide perovskite (MAPbI₃) nanocrystals to control charge transport between photoexcited perovskites and a metal electrode. A thin hybridized nanocrystalline film was found to cause an efficient photomultiplication reaction based on hole accumulation at photoexcited perovskite nanoparticles and charge tunneling across the Eu complex molecules under application of a low external bias (-0.5 V). A photodetecting device based on the Eu complex and perovskite absorber demonstrated photoinduced current generation at extremely high quantum conversion efficiency of 290 000% for weak monochromatic light (<1 mW cm^-2), yielding a power responsivity value up to 1289 A W^-1. High sensitivity of photodetection was enabled by using nanosized particles (<5 nm) of perovskite having a high surface area in contact with the Eu complex, while sensitivity was reduced by use of thick and large particle perovskite layers.