Conspectus Elaborate chemical synthesis methods allow the production of various types of inorganic nanocrystals (NCs) with uniform shape and size distributions. Many single-step synthesis approaches, ...such as the reduction of metal ions, the decomposition of metal complexes, double replacement reactions, and hydrolysis, have been adapted to promote the generation of monodisperse metal and ionic NCs. However, the question has become, how can we synthesize NCs with thermodynamically metastable phases or very complex structures? The transformation of already-synthesized NCs via elemental substitutions, such as ion exchange reactions for ionic NCs and galvanic replacement reactions for metal NCs, can overcome the difficulties facing conventional one-step syntheses. In particular, NC ion exchange reactions have been studied with numerous combinations of foreign ions and ionic NCs with various shapes. They have been investigated extensively because the reactions proceed under relatively mild conditions thanks to the large surface-to-volume ratio of the NCs relative to their bulk form. The functionality of the resulting ionic NCs, including semiconducting and plasmonic properties, can be easily tuned in a wide range, from the visible to near-infrared. Because anions generally have much larger ionic radii than cations within the frameworks of NCs, the cation exchange reactions proceed much faster than the anion exchange reactions. For ionic NCs above a critical size, the anion framework remains intact, and the original shape of the parent NCs is retained throughout the cation exchange reaction. In contrast, the anion exchange reaction often provides the new NCs with unique structures, such as hollow or anisotropically phase-segregated assemblies. This Account focuses on the full and partial ion exchange reactions involving ionic NCs, which have been thoroughly investigated by our group and others while highlighting important aspects such as the preservation of appearance and dimensions. First, we discuss how each type of ion exchange reaction progresses to understand the morphologies and crystal structures of their final products. This discussion is supported by emphasizing important examples, which help to explore the formation of NCs with thermodynamically metastable phases and complex structures, and other significant features of the ion exchange reactions leading to structure-specific functions. As a special case, we examine how the shape-dependent anionic framework (surface anion sublattice and stacking pattern) of polyhedral Cu2O NCs determines the crystalline structure of the anion-exchanged products of hollow Cu x S NCs. In addition, we review the characteristic anion exchange behavior of metal halide perovskite NCs observed in our laboratory and other laboratories. Finally, a general outline of the transformation of NCs via ion exchange reactions and future prospects in this field are provided.
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IJS, KILJ, NUK, PNG, UL, UM
OBJECTIVES:Clinicians often encounter adult patients with septic shock who fail to respond to fluid therapy and vasopressors. There is an increasing interest in venoarterial extracorporeal membranous ...oxygenation in the treatment of patients with septic shock, but its outcomes and safety remain unclear. The aim of this study is to describe in-hospital mortality and complication rate in adult patients with septic shock who underwent venoarterial extracorporeal membranous oxygenation, and to identify patients who may potentially benefit from venoarterial extracorporeal membranous oxygenation.
DATA SOURCES:The protocol for this systematic review was registered at International Prospective Register of Systematic Reviews (CRD42018098848). We searched MEDLINE, Embase, and Igaku Chuo Zasshi for studies of any design in which patients with septic shock were treated with venoarterial extracorporeal membranous oxygenation. Our search was updated on October 6, 2019.
STUDY SELECTION:Two independent reviewers assessed whether titles and abstracts met the eligibility criteria. Studies were included when patients met the following criteria1) age 18 years old or older; 2) septic shock; and 3) treated with venoarterial extracorporeal membranous oxygenation as hemodynamic support. When there were disagreements between reviewers, the full text was reviewed, and discussion was continued until a consensus was reached.
DATA EXTRACTION:Two authors independently extracted the selected patient and study characteristics and outcomes.
DATA SYNTHESIS:A total of 6,457 studies were screened. Six retrospective studies were included. The in-hospital mortality rate of patients with septic shock who underwent venoarterial extracorporeal membranous oxygenation was 76.7% (188/245). Four studies provided cardiac function with left ventricular ejection fraction and/or cardiac index. In two of these four studies where median left ventricular ejection fraction and cardiac index were 16.0% and 1.3 L/min/m and median left ventricular ejection fraction and mean cardiac index were 30.0% and 2.4 L/min/m, respectively, the in-hospital mortalities were markedly lower (14.8% and 28.6%, respectively) than the other two studies (78.1% and 91.5%, respectively) that included populations with median left ventricular ejection fraction of 25.0% and mean cardiac index of 2.1 L/min/m. Complications were reported in five studies (39 events/174 cases), hemorrhage (22 events/174 cases) being the most common.
CONCLUSIONS:Venoarterial extracorporeal membranous oxygenation remains a controversial treatment strategy in septic shock. The reported in-hospital mortality rates in patients with sepsis-induced cardiogenic shock who underwent venoarterial extracorporeal membranous oxygenation were quite inconsistent. There is a need for well-designed studies to assess the benefit and safety of venoarterial extracorporeal membranous oxygenation in patients with sepsis-induced cardiogenic shock.
Abstract
Background
Previous studies have found various incidences of right ventricular (RV) injury and its association with clinical outcome in patients with acute respiratory distress syndrome ...(ARDS). In this systematic review and meta-analysis, we aimed to investigate the impact of the presence of RV injury on mortality in patients with ARDS.
Method
We searched Medline, Embase, and the Cochrane Central Register of Controlled Trials for studies investigating the association between RV injury and mortality. Two authors independently evaluated whether studies meet eligibility criteria and extracted the selected patients’ and studies’ characteristics and outcomes. RV injury was diagnosed by trans-thoracic echocardiogram (TTE), trans-esophageal echocardiogram (TEE) and PAC (pulmonary artery catheter) in the included studies. The primary outcome was the association between mortality and the presence of RV injury in patients with ARDS. The overall reported mortality was defined as either the intensive care unit (ICU) mortality, in-hospital mortality, or mortality within 90 days, and short-term mortality was defined as ICU-mortality, in-hospital mortality, or mortality within 30 days.
Results
We included 9 studies (
N
= 1861 patients) in this meta-analysis. RV injury that included RV dysfunction, RV dysfunction with hemodynamic compromise, RV failure, or acute cor-pulmonale was present in 21.0% (391/1,861). In the pooled meta-analysis, the presence of RV injury in patients with ARDS was associated with significantly higher overall mortality (OR 1.45, 95% CI 1.13–1.86,
p
-value = 0.003,
I
2
= 0%), as well as short-term mortality (OR 1.48, 95% CI 1.14–1.93,
p
-value = 0.003,
I
2
= 0%).
Conclusion
In this systematic review and meta-analysis including 1861 patients with ARDS, the presence of RV injury was significantly associated with increased overall and short-term mortality.
Trial registration
: The protocol was registered at PROSPERO (CRD42020206521).
Metal–halide perovskite nanocrystals (NCs) are promising photonic materials for use in solar cells, light-emitting diodes, and lasers. The optoelectronic properties of these devices are determined by ...the excitons and exciton complexes confined in their NCs. In this study, we determined the relaxation dynamics of charged excitons and biexcitons in CsPbBr3 NCs using femtosecond transient-absorption (TA), time-resolved photoluminescence (PL), and single-dot second-order photon correlation spectroscopy. Decay times of ∼40 and ∼200 ps were obtained from the TA and PL decay curves for biexcitons and charged excitons, respectively, in NCs with an average edge length of 7.7 nm. The existence of charged excitons even under weak photoexcitation was confirmed by the second-order photon correlation measurements. We found that charged excitons play a dominant role in luminescence processes of CsPbBr3 NCs. Combining different spectroscopic techniques enabled us to clarify the dynamical behaviors of excitons, charged excitons, and biexcitons.
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Combining the superior optical properties of their bulk counterparts with quantum confinement effects, lead halide perovskite nanocrystals are unique laser materials with low-threshold optical gain. ...In such nonlinear optical regimes, multiple excitons are generated in the nanocrystals and strongly affect the optical gain through many-body interactions. Here, we investigate the exciton–exciton interactions in CsPbI3 nanocrystals by femtosecond transient absorption spectroscopy. From the analysis of the induced absorption signal observed immediately after the pump excitation, we estimated the binding energy for the hot biexcitons that are composed of an exciton at the band edge and a hot exciton generated by the pump pulse. We found that the exciton–exciton interaction becomes stronger for hot excitons with greater excess energies and that the optical gain can be controlled by changing the excess energy of the hot excitons.
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We study the origin of photoluminescence (PL) intermittency in formamidinium lead bromide (FAPbBr3, FA = HC(NH2)2) nanocrystals and the impact of postsynthetic surface treatments on the PL ...intermittency. Single-dot spectroscopy revealed the existence of different individual nanocrystals exhibiting either a blinking (binary on–off switching) or flickering (gradual undulation) behavior of the PL intermittency. Although the PL lifetimes of blinking nanocrystals clearly correlate with the individual absorption cross sections, those of flickering nanocrystals show no correlation with the absorption cross sections. This indicates that flickering has an extrinsic origin, which is in contrast to blinking. We demonstrate that the postsynthetic surface treatment with sodium thiocyanate improves the PL quantum yields and completely suppresses the flickering, while it has no significant effect on the blinking behavior. We conclude that the blinking is caused by Auger recombination of charged excitons, and the flickering is due to a temporal drift of the exciton recombination rate induced by surface-trapped electrons.
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In diabetic peripheral neuropathy (DPN), metabolic disorder by hyperglycemia progresses in peripheral nerves. In addition to the direct damage to peripheral neural axons, the homeostatic mechanism of ...peripheral nerves is disrupted by dysfunction of the blood-nerve barrier (BNB) and Schwann cells. The disruption of the BNB, which is a crucial factor in DPN development and exacerbation, causes axonal degeneration via various pathways. Although many reports revealed that hyperglycemia and other important factors, such as dyslipidemia-induced dysfunction of Schwann cells, contributed to DPN, the molecular mechanisms underlying BNB disruption have not been sufficiently elucidated, mainly because of the lack of in vitro studies owing to difficulties in establishing human cell lines from vascular endothelial cells and pericytes that form the BNB. We have developed, for the first time, temperature-sensitive immortalized cell lines of vascular endothelial cells and pericytes originating from the BNB of human sciatic nerves, and we have elucidated the disruption to the BNB mainly in response to advanced glycation end products in DPN. Recently, we succeeded in developing an in vitro BNB model to reflect the anatomical characteristics of the BNB using cell sheet engineering, and we established immortalized cell lines originating from the human BNB. In this article, we review the pathologic evidence of the pathology of DPN in terms of BNB disruption, and we introduce the current in vitro BNB models.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The rapid manufacturing of transparent SiO2 glass components via a hybridized 3D structuring approach for photo-curing and green machining, followed by a fast debinding/sintering process (at a ...heating rate of 20 °C min–1), is reported to be based on the design of a new series of interparticle photo-cross-linkable suspensions. In these suspensions, small amounts of multifunctional acrylates and silane alkoxides with acryloyl groups (A-Si) are co-photo-polymerized and further reacted with SiO2 particles modified using functionalized polyethyleneimine to form hybridized interparticle networks. The addition of A-Si increases the interparticle cross-linking densities, leading to an improvement in the mechanical properties and green machinability of the photo-cured bodies. Furthermore, the A-Si component in the cross-links forms siloxane-based networks among SiO2 particles in situ during the debinding/sintering process, which increases the mechanical strength of the debinded bodies and successfully prevents structural collapses under rapid heating conditions. The study demonstrates that the photo-cured body from the newly designed suspensions can be green-machined into pillars, microfluids, and assembling blocks and can be sintered into highly transparent SiO2 glass components. Overall, this work provides new options for the time- and energy-effective processing of SiO2 glass materials with tailor-made 3D structures.
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Antheraea yamamai silk contains long poly(alanine) sequences that contribute to β-sheet crystals, which are responsible for the high tensile strength of silk fibers. We determined the crystal ...structure, physical properties, and morphology of A. yamamai cocoon silk fibers. The crystal lattice of A. yamamai silk fiber consists of antiparallel β-pleated sheets with an orthogonal unit cell (a = 10.72 Å, b = 9.73 Å, c fiber axis = 6.80 ± 0.05 Å). Wide-angle X-ray scattering and birefringence measurements revealed that stretching deformation does not affect the crystal structure but contributes to alignment of silk molecules along the fiber axis in the partial amorphous phase. Crystallinity and amino acid sequence analyses suggested that the poly(alanine) region can be partially crystallized. The long poly(alanine) sequences therefore do not contribute to the mechanical, thermal, or structural properties of A. yamamai silk. Our results may aid the design and development of A. yamamai silk-based materials.
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•The crystal structure of Antheraea yamamai silk were investigated.•The mechanical and thermal properties of A. yamamai silk were characterized.•The poly(alanine) sequence was partially crystalized in the beta-sheet crystals.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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