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Transcatheter aortic valve implantation (TAVI)-related Stanford type B aortic dissection is an extremely rare but potentially fatal complication. Here, we present a case of 82-year-old man who developed acute type B aortic dissection during transfemoral TAVI. During successful TAVI procedure, dissection in the descending aorta was demonstrated by transesophageal echocardiography. Computed tomography( CT) clearly showed Stanford type B aortic dissection and an intimal tear in severely tortuous part of the descending aorta. Cause of aortic dissection was supposed to be related to the guidewire or the device that passed across affected position. The patient showed no complication associated with aortic dissection, such as rupture or malperfusion. Therefore, he was treated conservatively, and follow-up CT confirmed progressive clotting of the false lumen. Although the indication for TAVI has got broaden recently, physicians should be always aware of possible aortic dissection.
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Dissecção Aórtica , Substituição da Valva Aórtica Transcateter , Idoso de 80 Anos ou mais , Dissecção Aórtica/diagnóstico por imagem , Dissecção Aórtica/etiologia , Dissecção Aórtica/cirurgia , Ecocardiografia Transesofagiana , Humanos , Masculino , Tomografia Computadorizada por Raios X , Substituição da Valva Aórtica Transcateter/efeitos adversosRESUMO
Metal nanoclusters (NCs), which are composed of about 250 or fewer metal atoms, possess great potential as novel functional materials. Fundamental research on metal NCs gradually started in the 1960s, and since 2000, thiolate (SR)-protected metal NCs have been the main metal NCs actively studied. The precise and systematic isolation of SR-protected metal NCs has been achieved in 2005. Since then, research on SR-protected metal NCs for both basic science and practical application has rapidly expanded. This review describes this recent progress in the field of SR-protected metal NCs in three areas: synthesis, understanding, and application. Specifically, the recent study of alloy NCs and connected structures composed of NCs is highlighted in the "synthesis" section, recent knowledge on the reactivity of NCs in solution is highlighted in the "understanding" section, and the applications of NCs in the energy and environmental field are highlighted in the "application" section. This review provides insight on the current state of research on SR-protected metal NCs and discusses the challenges to be overcome for further development in this field as well as the possibilities that these materials can contribute to solving the problems facing modern society.
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Ouro , Nanopartículas Metálicas , LigasRESUMO
Invited for the cover of this issue is the group of Yuichi Negishi at Tokyo University of Science. The image depicts the alloy nanoclusters reported in this review. Read the full text of the article at 10.1002/chem.202001877.
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Metal nanoclusters (NCs) have a particle size of about one nanometer, which makes them the smallest unit that can give a function to a substance. In addition, metal NCs possess physical and chemical properties that are different from those of the corresponding bulk metals. Metal NCs with such characteristics are expected to be important for use in nanotechnology. Research on the precise synthesis of metal NCs and elucidation of their physical/chemical properties and functions is being actively conducted. When metal NCs are alloyed, it is possible to obtain further various electronic and geometrical structures and functions. Thus, research on alloy NCs has become a hot topic in the study of metal NCs and the number of publications on alloy NCs has increased explosively in recent years. Such publications have provided much insight into the effects of alloying on the electronic structure and function of metal NCs. However, the rapid increase in knowledge has made it difficult for researchers (especially those new to the field) to grasp all of it. Therefore, in this review, we summarize the reported chemical composition, geometrical structure, electronic structure, and physical and chemical properties of Aun-x Mx (SR)m , Agn-x Mx (SR)m , Aun-x Mx (PR3 )l (SR)m , and Agn-x Mx (PR3 )l (SR)m (Au=gold, Ag=silver, M=heteroatom, PR3 =phosphine, and SR=thiolate) NCs. This review is expected to help researchers understand the characteristics of alloy NCs and lead to clear design guidelines to develop new alloy NCs with intended functions.
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We present a single-channel 5.12 Tbit/s polarization-multiplexed DQPSK transmission over 300 km at 1.28 Tbaud using a non-coherent Nyquist pulse. An ultrafast OTDM demultiplexer for 1.28 Tbaud Nyquist pulses was newly developed with a mode-locked fiber laser operating in the L band as a control pulse source. Thanks to the high PMD tolerance of Nyquist pulses, a 300 km transmission was successfully demonstrated for the first time at such a high symbol rate.
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We evaluate the dependence of system performance on the roll-off factor, α, of a Nyquist pulse in a single-channel 1.28 Tbit/s-525 km transmission both experimentally and analytically. Low α values are preferable in terms of spectral efficiency and tolerance to chromatic dispersion and polarization-mode dispersion, while a strong overlap with neighboring symbols results in larger nonlinear impairments. On the other hand, a Nyquist pulse with high α values also suffers from nonlinearity due to higher peak power. As a result, we found experimentally that the optimum α value is 0.4~0.6, which agrees well with the analysis.
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We propose the ultrahigh-speed demultiplexing of Nyquist OTDM signals using an optical Nyquist pulse as both a signal and a sampling pulse in an all-optical nonlinear switch. The narrow spectral width of the Nyquist pulses means that the spectral overlap between data and control pulses is greatly reduced, and the control pulse itself can be made more tolerant to dispersion and nonlinear distortions inside the nonlinear switch. We apply the Nyquist control pulse to the 640 to 40 Gbaud demultiplexing of DPSK and DQPSK signals using a nonlinear optical loop mirror (NOLM), and demonstrate a large performance improvement compared with conventional Gaussian control pulses. We also show that the optimum spectral profile of the Nyquist control pulse depends on the walk-off property of the NOLM.
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We demonstrate a single-channel 2.56 Tbit/s polarization-multiplexed DQPSK transmission using 640 Gbaud non-coherent optical Nyquist pulses. By virtue of a large tolerance to polarization-mode dispersion, the detrimental depolarization-induced crosstalk was reduced by 3.8 dB compared with RZ pulses. As a result, the transmission distance was substantially extended to 525 km compared with the distance of 300 km obtained with a Gaussian pulse.
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OBJECTIVES: Hypophosphatasia (HPP) is a rare skeletal dysplasia caused by variants in the alkaline phosphatase (ALPL) gene. More than 400 pathogenic variants of the ALPL gene have been registered in the ALPL gene variant database. Here, we describe the case of a Japanese child with odonto-hypophsphatasia (odonto-HPP) and a novel ALPL variant. CASE PRESENTATION: At the age of 2 years and 1 month, he prematurely lost one deciduous tooth, with the root intact, when he fell and hit his face lightly. Three months later, he lost another adjacent deciduous tooth without incentive. His serum alkaline phosphatase (ALP) level was 72â¯U/L. His urine phosphoethanolamine (PEA) level was extremely high at 938⯵mol/mg·Cre. The serum pyridoxal 5'-phosphaye (PLP) level was 255.9â¯nmol/L. Based on the clinical symptoms and laboratory findings, the patient was clinically diagnosed with odonto-HPP. Genetic analysis of the ALPL gene revealed a heterozygous variant (NM_000478.6:c.1151C>A, p.Thr384Lys). CONCLUSIONS: We report a case of odonto-HPP with a novel variant in the ALPL gene. HPP is a rare disease, and the heterozygous mutation in the ALPL gene highlights the novelty of this case.
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Hipofosfatasia , Masculino , Criança , Humanos , Pré-Escolar , Hipofosfatasia/genética , Hipofosfatasia/diagnóstico , Fosfatase Alcalina , Mutação , HeterozigotoRESUMO
Analyzing the dynamics of information diffusion cascades and accurately predicting their behavior holds significant importance in various applications. In this paper, we concentrate specifically on a recently introduced contrastive cascade graph learning framework, for the task of predicting cascade popularity. This framework follows a pre-training and fine-tuning paradigm to address cascade prediction tasks. In a previous study, the transferability of pre-trained models within the contrastive cascade graph learning framework was examined solely between two social media datasets. However, in our present study, we comprehensively evaluate the transferability of pre-trained models across 13 real datasets and six synthetic datasets. We construct several pre-trained models using real cascades and synthetic cascades generated by the independent cascade model and the Profile model. Then, we fine-tune these pre-trained models on real cascade datasets and evaluate their prediction accuracy based on the mean squared logarithmic error. The main findings derived from our results are as follows. (1) The pre-trained models exhibit transferability across diverse types of real datasets in different domains, encompassing different languages, social media platforms, and diffusion time scales. (2) Synthetic cascade data prove effective for pre-training purposes. The pre-trained models constructed with synthetic cascade data demonstrate comparable effectiveness to those constructed using real data. (3) Synthetic cascade data prove beneficial for fine-tuning the contrastive cascade graph learning models and training other state-of-the-art popularity prediction models. Models trained using a combination of real and synthetic cascades yield significantly lower mean squared logarithmic error compared to those trained solely on real cascades. Our findings affirm the effectiveness of synthetic cascade data in enhancing the accuracy of cascade popularity prediction.
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Aprendizagem , Mídias Sociais , Humanos , Difusão , IdiomaRESUMO
Neuromorphic computing using spintronic devices, such as spin-torque oscillators (STOs), has been intensively studied for energy-efficient data processing. One of the critical issues in this application is stochasticity in magnetization dynamics, which limits the accuracy of computation. Such stochastic behavior, however, plays a key role in stochastic computing and machine learning. It is therefore important to develop methods for both suppressing and enhancing stochastic response in spintronic devices. We report on experimental investigations on control of stochastic quantity, such as the width of a distribution of transient time in magnetization dynamics in vortex-type STO. The spin-transfer effect can suppress stochasticity in transient dynamics from a non-oscillating to oscillating state, whereas an application of a radio-frequency magnetic field is effective in reducing stochasticity on the time evolution of the oscillating state.
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To establish an ultimate energy conversion system consisting of a water-splitting photocatalyst and a fuel cell, it is necessary to further increase the efficiencies of the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and the oxygen reduction reaction (ORR). Recently, it was demonstrated that thiolate (SR)-protected gold clusters, Aun(SR)m, and their related alloy clusters can serve as model catalysts for these three reactions. However, as the previous data have been obtained under different experimental conditions, it is difficult to use them to gain a deep understanding of the means to attain higher activity in these reactions. Herein, we measured the HER, OER, and ORR activities of Aun(SR)m and alloy clusters containing different numbers of constituent atoms, ligand functional groups, and heteroatom species under identical experimental conditions. We obtained a comprehensive set of results that illustrates the effect of each parameter on the activities of the three reactions. Comparison of the series of results revealed that decreasing the number of constituent atoms in the cluster, decreasing the thickness of the ligand layer, and substituting Au with Pd improve the activities in all reactions. Taking the stability of the cluster into consideration, [Au24Pd(PET)18]0 (PET = 2-phenylethanethiolate) can be considered as a metal cluster with high potential as an HER, OER, and ORR catalyst. These findings are expected to provide clear design guidelines for the development of highly active HER, OER, and ORR catalysts using Aun(SR)m and related alloy clusters, which would allow realization of an ultimate energy conversion system.
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2-Phenylethanethiolate (PET) and 4-tert-butylbenzenethiolate (TBBT) are the most frequently used ligands in the study of thiolate (SR)-protected metal clusters. However, the effect of difference in the functional group between these ligands on the fundamental properties of the clusters has not been clarified. We synthesized [Au24Pt(TBBT)18]0, which has the same number of metal atoms, number of ligands, and framework structure as [Au24Pt(PET)18]0, by replacing ligands of [Au24Pt(PET)18]0 with TBBT. It was found that this ligand exchange is reversible unlike the case of other metal-core clusters. A comparison of the geometrical/electronic structure and stability of the clusters between [Au24Pt(PET)18]0 and [Au24Pt(TBBT)18]0 revealed three things with regard to the effect of ligand change from PET to TBBT on [Au24Pt(SR)18]0: (1) the induction of metal-core contraction and Au-S bond elongation, (2) no substantial effect on the HOMO-LUMO gap but a clear difference in optical absorption in the visible region, and (3) the decrease of stabilities against degradation in solution and under laser irradiation. By using these two clusters as model clusters, it is expected that the effects of the structural difference of ligand functional-groups on the physical properties and functions of clusters, such as catalytic ability and photoluminescence, would be clarified.
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A tricationic shape-persistent macrocycle was obtained by methylation on the nitrogen atoms of the three 3,5-pyridylene groups of an alternating 2,6-/3,5-substituted ethynylpyridine macrocycle. The tricationic macrocycle recognized melamine in polar solvents such as DMSO and water, and the host-guest association in water induced a higher-order aggregate confirmed by UV-vis titration and dynamic light scattering experiments. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy indicated that fibrous network structures resulted from the stacking of the macrocycle and melamine complex.
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Piridinas/química , Triazinas/química , Cátions , Microscopia de Força Atômica , Microscopia Eletrônica de Transmissão , Estrutura Molecular , Solventes , Água/químicaRESUMO
Macrocyclic compounds consisting of three 2,6-pyridylene and three 3,5-pyridylene units linked by acetylene bonds were synthesized by a Sonogashira reaction. The X-ray structures showed π-stacked pairs of two macrocycles, in which a 2,6-pyridylene unit of the one molecule overlaps a 3,5-pyridylene of the other molecule because of dipole-dipole interaction. Atomic force microscope (AFM) measurements revealed fibril structures indicating the stacking of the rigid planar macrocycles. Hydrogen-bonding ability of the macrocyclic inside was demonstrated by the addition of octyl ß-D-glucopyranoside.