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1.
Inorg Chem ; 63(26): 12167-12174, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38877609

RESUMO

We developed a new penternary wurtzitic nitride system Li1-xZnxGe2-xGaxN3 (0 ≤ x ≤ 1) by hybridizing LiGe2N3 and ZnGeGaN3. Fairly stoichiometric fine powder samples were synthesized by the reduction-nitridation process at 900 °C. While the end member LiGe2N3 possessed a relatively large band gap of 4.16 eV, the band gap of the developed penternary system varied in a broad range of 3.81 to 3.10 eV, showing promising responsivity to the solar spectrum. The crystal structure of LiGe2N3 was precisely determined by time-of-flight neutron powder diffraction for the first time, revealing the complete ordering of Li and Ge in the Cmc21 structure. The structural evolution from completely ordered LiGe2N3 to fully disordered ZnGeGaN3 was quantitatively analyzed by Rietveld refinement based on a partially disordered Cmc21 model, and the obtained results were also supported by 71Ga solid-state NMR spectroscopy. The synthesized Li1-xZnxGe2-xGaxN3 powder samples exhibited photocatalytic activities for the water reduction and oxidation reactions under solar light irradiation, with the H2 evolution rate of 0.3-59.0 µmol/h and the O2 evolution rate of 3.1-296.2 µmol/h, depending on the composition. Stable solar hydrogen generation of up to 48 h was demonstrated by the x = 0.80 sample, with the total amount of H2 evolved over 1.6 mmol and an external quantum efficiency of 2.1%.

2.
Int J Cardiol ; 396: 131554, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-37875211

RESUMO

BACKGROUND: There is a lack of predictive biomarkers for the onset or activity of protein-losing enteropathy (PLE), a Fontan procedure-associated complication. Here, we aimed to identify the gut microbiota composition of patients with active PLE and investigate its relationship with PLE activity. METHODS: This multicenter case-control study involved patients who developed PLE (n = 16) after the Fontan procedure and those who did not (non-PLE; n = 20). Patients with PLE who maintained a serum albumin level of ≥3 g/dL for >1 year were included in the remissive-stage-PLE group (n = 9) and those who did not maintain this level were included in the active-PLE group (n = 7). 16S rRNA gene sequencing analysis of fecal samples was performed using QIIME2 pipeline. Alpha (Shannon and Faith's phylogenetic diversity indices) and beta diversity was assessed using principal coordinate analysis based on unweighted UniFrac distances. RESULTS: Shannon and Faith's phylogenetic diversity indices were lower in the active-PLE group than in the remissive-stage- (q = 0.028 and 0.025, respectively) and non-PLE (q = 0.028 and 0.017, respectively) groups. Analysis of beta diversity revealed a difference in the microbiota composition between the active-PLE and the other two groups. Linear discriminant effect size analysis demonstrated differences in the relative abundance of Bifidobacterium and Granulicatella spp., and Ruminococcus torques between patients with active- and those with remissive-stage-PLE. CONCLUSIONS: Gut microbiota dysbiosis was observed in patients with active PLE. Changes in the bacterial composition of the gut microbiota and decreased diversity may be associated with the severity of PLE.


Assuntos
Técnica de Fontan , Microbioma Gastrointestinal , Enteropatias Perdedoras de Proteínas , Humanos , Técnica de Fontan/efeitos adversos , Enteropatias Perdedoras de Proteínas/diagnóstico , Enteropatias Perdedoras de Proteínas/etiologia , Estudos de Casos e Controles , Disbiose/diagnóstico , Disbiose/complicações , Filogenia , RNA Ribossômico 16S/genética
3.
J Phys Chem Lett ; 14(42): 9516-9520, 2023 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-37852194

RESUMO

For the extraction of hydrogen from ammonia at low temperatures, we investigated Ni-based catalysts fabricated by the thermal decomposition of RNi5 intermetallics (R = Ce or Y). The interconnected microstructure formed via phase separation between the Ni catalyst and the resulting oxide support was observed to evolve via low-temperature thermal decomposition of RNi5. The resulting Ni/CeO2 nanocomposite exhibited superior catalytic activity of ∼25% at 400 °C for NH3 cracking. The high catalytic activity was attributed to the interlocking of Ni nanoparticles with the CeO2 framework. The growth of Ni nanoparticles was prevented by this interconnected microstructure, in which the Ni nanoparticles incorporated nitrogen owing to the size effect, whereas Ni does not commonly form nitrides. To the best of our knowledge, this is a unique example of a microstructure that enhances catalytic NH3 cracking.

4.
Sci Technol Adv Mater ; 23(1): 547-578, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36212682

RESUMO

This review is dedicated to various functional nanoarchitectonic nanocomposites based on molecular octahedral metal atom clusters (Nb6, Mo6, Ta6, W6, Re6). Powder and film nanocomposites with two-dimensional, one-dimensional and zero-dimensional morphologies are presented, as well as film matrices from organic polymers to inorganic layered oxides. The high potential and synergetic effects of these nanocomposites for biotechnology applications, photovoltaic, solar control, catalytic, photonic and sensor applications are demonstrated. This review also provides a basic level of understanding how nanocomposites are characterized and processed using different techniques and methods. The main objective of this review would be to provide guiding significance for the design of new high-performance nanocomposites based on transition metal atom clusters.

5.
Sci Technol Adv Mater ; 23(1): 446-456, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36081837

RESUMO

The development of highly ultraviolet (UV) and near-infrared (NIR) absorbent transparent coatings is an important enabling technology and area of research for environmental sustainability and energy conservation. Different amounts of K4[{Nb5TaXi 12}Xa 6] cluster compounds (X = Cl, Br) dispersed into polyvinylpyrrolidone matrices were prepared by a simple, nontoxic and low-cost wet chemical method. The resulting solutions were used to fabricate visibly transparent, highly UV and NIR absorbent coatings by drop casting. The properties of the solution and films were investigated by complementary techniques (optical absorption, electrospray ionization mass spectrometry and Raman spectroscopy). The UV and NIR absorption of such samples strongly depended on the concentration, dispersion and oxidation state of the [{Nb5TaXi 12}Xa 6] nanocluster-based units. By varying and controlling these parameters, a remarkable improvement of the figures of merit TL/TE and SNIR for solar-glazing applications was achieved compared to the previous results on nanocomposite coatings based on metal atom clusters.

6.
Circ J ; 87(1): 130-138, 2022 12 23.
Artigo em Inglês | MEDLINE | ID: mdl-35979562

RESUMO

BACKGROUND: The prospective Control of HEART rate in inFant and child tachyarrhythmia with reduced cardiac function Using Landiolol (HEARTFUL) study investigated the effectiveness and safety of landiolol, a short-acting ß1 selective blocker, in children.Methods and Results: Twenty-five inpatients aged ≥3 months to <15 years who developed supraventricular tachyarrhythmias (atrial fibrillation, atrial flutter, supraventricular tachycardia, and inappropriate sinus tachycardia) were treated with landiolol. The primary endpoint, the percent of patients with a reduction in heart rate ≥20% from the initial rate of tachycardia, or termination of tachycardia at 2 h after starting landiolol, was achieved in 12/25 patients (48.0%; 95% CI 28.4-67.6), which exceeded the predetermined threshold (38.0%). At 2 h after starting landiolol administration, heart rate had decreased by ≥20% in 45.8% (11/24) and recovery to sinus rhythm was achieved in 40.0% (6/15) of the patients. Adverse reactions (ARs) occurred in 24.0% (6/25) of patients, and the study was discontinued in 4.0% (1/25) of the patients; however, none of these ARs were considered serious. The most common AR was hypotension (20.0% [5/25] of patients). CONCLUSIONS: The HEARTFUL study has demonstrated the efficacy of landiolol, by reducing heart rate or terminating tachycardia, in pediatric patients with supraventricular tachyarrhythmias. Although serious ARs and concerns were not identified in this study, physicians should be always cautious of circulatory collapse due to hypotension.


Assuntos
Fibrilação Atrial , Hipotensão , Humanos , Criança , Lactente , Frequência Cardíaca , Estudos Prospectivos , Taquicardia/tratamento farmacológico , Ureia/efeitos adversos , Antagonistas Adrenérgicos beta/efeitos adversos
7.
Nanomaterials (Basel) ; 12(14)2022 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-35889559

RESUMO

In the frame of the nanoarchitectonic concept, the objective of this study was to develop simple and easy methods to ensure the preparation of polymorphic HfO2 thin film materials (<200 nm) having the best balance of patterning potential, reproducibility and stability to be used in optical, sensing or electronic fields. The nanostructured HfO2 thin films with micropatterns or continuous morphologies were synthesized by two different methods, i.e., the micropatterning of sol-gel solutions by deep ultraviolet (DUV) photolithography or the electrophoretic deposition (EPD) of HfO2 nanoparticles (HfO2-NPs). Amorphous and monoclinic HfO2 micropatterned nanostructured thin films (HfO2-DUV) were prepared by using a sol-gel solution precursor (HfO2-SG) and spin-coating process following by DUV photolithography, whereas continuous and dense monoclinic HfO2 nanostructured thin films (HfO2-EPD) were prepared by the direct EPD of HfO2-NPs. The HfO2-NPs were prepared by a hydrothermal route and studied through the changing aging temperature, pH and reaction time parameters to produce nanocrystalline particles. Subsequently, based on the colloidal stability study, suspensions of the monoclinic HfO2-NPs with morphologies near spherical, spindle- and rice-like shapes were used to prepare HfO2-EPD thin films on conductive indium-tin oxide-coated glass substrates. Morphology, composition and crystallinity of the HfO2-NPs and thin films were investigated by powder and grazing incidence X-ray diffraction, scanning electron microscopy, transmission electron microscopy and UV-visible spectrophotometry. The EPD and DUV photolithography performances were explored and, in this study, it was clearly demonstrated that these two complementary methods are suitable, simple and effective processes to prepare controllable and tunable HfO2 nanostructures as with homogeneous, dense or micropatterned structures.

8.
J Clin Immunol ; 42(8): 1696-1707, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-35902420

RESUMO

PURPOSE: The aim of this study is to evaluate the usefulness of T cell receptor excision circle (TREC) and/or kappa-deleting recombination excision circle (KREC) measurements integrated with diagnostic next-generation sequencing (NGS) analysis using a severe combined immunodeficiency (SCID) newborn screening (NBS) program. METHODS: TREC and/or KREC values were measured in 137,484 newborns between April 2017 and December 2021 using EnLite TREC (n = 80,791) or TREC/KREC kits (n = 56,693). For newborns with positive screening results, diagnostic NGS analysis was performed with a 349-gene panel to detect genetic mutations associated with primary immunodeficiencies (PIDs). RESULTS: A total of 145 newborns (0.11%) had abnormal TREC and/or KREC values, and a genetic diagnosis was established in 2 patients with SCID (1 in 68,742 newborns) (IL2RG-SCID and reticular dysgenesis) and 10 with non-SCID PIDs with T and/or B cell deficiencies (1 in 13,748 newborns) using NGS analysis. Furthermore, TREC values of 2849 newborns were measured and confirmed the significant correlation between the results of both TREC and TREC/KREC kits (P < 0.001) and naïve T cell counts. CONCLUSIONS: We performed the first large-scale TREC and TREC/KREC NBS programs in Japan. Our NBS programs followed by the diagnostic NGS analysis for newborns with abnormal TREC and/or KREC values are useful for the early identification and rapid molecular evaluation of not only SCID but also different non-SCID PIDs.


Assuntos
Imunodeficiência Combinada Severa , Recém-Nascido , Humanos , Imunodeficiência Combinada Severa/diagnóstico , Imunodeficiência Combinada Severa/genética , Triagem Neonatal/métodos , Japão , Linfócitos T , Sequenciamento de Nucleotídeos em Larga Escala , DNA , Receptores de Antígenos de Linfócitos T/genética
9.
Nanomaterials (Basel) ; 12(12)2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35745391

RESUMO

The antagonism between global energy needs and the obligation to slow global warming is a current challenge. In order to ensure sufficient thermal comfort, the automotive, housing and agricultural building sectors are major energy consumers. Solar control materials and more particularly, selective glazing are part of the solutions proposed to reduce global energy consumption and tackle global warming. In this context, these works are focused on developing new highly ultraviolet (UV) and near-infrared (NIR) absorbent nanocomposite coatings based on K4[{Nb6-xTaxXi12}Xa6]. (X = Cl, Br, 0 ≤ x ≤ 6) transition metal cluster compounds. These compounds contain cluster-based active species that are characterized by their strong absorption of UV and NIR radiations as well as their good transparency in the visible range, which makes them particularly attractive for window applications. Their integration, by solution processes, into a silica-polyethylene glycol or polyvinylpyrrolidone matrices is discussed. Of particular interest is the control and the tuning of their optical properties during the integration and shaping processes. The properties of the solutions and films were investigated by complementary techniques (UV-Vis-NIR spectrometry, ESI-MS, SEM, HRTEM, etc.). Results of these works have led to the development of versatile solar control coatings whose optical properties are competitive with commercialized material.

10.
J Electrocardiol ; 71: 74-78, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35183046

RESUMO

Two cases of focal atrial tachycardia probably originating from the pulmonary vein with onset later than 3 years of age are presented. Both cases had associated variable atrioventricular conduction and showed no signs of heart failure, and they converted to sinus rhythm at the time of puberty. In cases of focal atrial tachycardia originating from the pulmonary vein with onset later than 3 years of age, drug therapy may be effective. Even if drug therapy is not effective, changes in the autonomic nervous system are reflected strongly in the pulmonary veins, so that changes in autonomic nervous system regulation with growth might terminate focal atrial tachycardia. Therefore, focal atrial tachycardia originating from the pulmonary vein with onset later than 3 years of age might have a better prognosis.


Assuntos
Fibrilação Atrial , Ablação por Cateter , Veias Pulmonares , Taquicardia Atrial Ectópica , Adolescente , Fibrilação Atrial/diagnóstico , Eletrocardiografia , Humanos , Prognóstico , Veias Pulmonares/cirurgia
11.
Reprod Biomed Online ; 44(1): 163-170, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34819250

RESUMO

RESEARCH QUESTION: What is the proportion of infants born as a result of assisted reproductive technology ART across different types of neonatal critical congenital heart disease (CCHD) in a Japanese population? DESIGN: A retrospective analysis of 418 consecutive infants with CCHD that required catheter treatment or surgery within the first 28 days of life or ductal-dependent lesions, in two paediatric centres in Japan, between January 2014 and December 2019. The proportion of ART in infants with each type of CCHD was evaluated. The proportion of ART in infants with univentricular heart defect (UVH) compared with those with biventricular heart defect (BVH) was evaluated. RESULTS: The study group included 229 boys and 189 girls, with a gestational age of 38 ± 2 weeks. Overall, 61 infants (14.6%) were conceived by fertility treatment with 46 (11.0%) conceived by ART. Univentricular heart defect and BVH were identified in 111 infants (26.6%) and 307 infants (73.4%), respectively. The proportion of infants conceived by ART was significantly higher in UVH (16.2%) than in BVH (9.1%) (OR 2.28, 95% CI 1.11 to 4.68, P = 0.025), regardless of maternal age and maternal history of miscarriage. CONCLUSIONS: The proportion of ART in infants with CCHD, especially UVH, was high. These findings could form the basis of a rationale for carrying out fetal echocardiography in fetuses conceived by ART.


Assuntos
Cardiopatias Congênitas , Coração Univentricular , Criança , Feminino , Cardiopatias Congênitas/epidemiologia , Humanos , Lactente , Recém-Nascido , Recém-Nascido Prematuro , Japão , Masculino , Gravidez , Técnicas de Reprodução Assistida , Estudos Retrospectivos
12.
Sci Technol Adv Mater ; 22(1): 758-771, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34566493

RESUMO

A novel heterogeneous catalytic nanomaterial based on a molybdenum cluster-based halide (MC) and a single-layered copper hydroxynitrate (CHN) was first prepared by colloidal processing under ambient conditions. The results of the elemental composition and crystalline pattern indicated that CHN was comprehensively synthesized with the support of the MC compound. The absorbing characteristic in the ultraviolet and near-infrared regions was promoted by both of the ingredients. The proper chemical interaction between the materials is a crucial reason to modify the structure of the MCs and only a small decrease in the magnetic susceptibility of CHN. The heterogeneous catalytic activity of the obtained MC@CHN material was found to have a high efficiency and excellent reuse when it is activated by hydrogen peroxide (H2O2) for the degrading reaction of the organic pollutant at room temperature. A reasonable catalytic mechanism was proposed to explain the distinct role of the copper compound, Mo6 compound, and H2O2 in the production of the radical hydroxyl ion. This novel nanomaterial will be an environmentally promising candidate for dye removal.

13.
J Cardiol ; 78(3): 213-218, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-33648806

RESUMO

BACKGROUND: The indication of Fontan conversion (FC) from atriopulmonary connection (APC) to total cavopulmonary connection (TCPC) is unclear. We sought to analyze the mid-term outcome of prophylactic and therapeutic Fontan conversion compared with that of primary TCPC. METHODS: Patients with a univentricular heart who underwent cardiac catheterization at >18 years of age between July 2005 and July 2019 were included and divided into three groups: symptomatic APC patients who underwent therapeutic FC (t-FC, n = 13), asymptomatic APC patients after prophylactic FC (p-FC, n = 15), and patients who had primary TCPC procedure (pTCPC, n = 24). RESULTS: The mean last follow up was at the age of 32.0 ± 7.8, 26.8 ± 3.8, and 27.3 ± 7 years (p = 0.07) in t-FC, p-FC, and pTCPC, respectively. There was no late death. All of t-FC and 12 (80%) of p-FC cases underwent concomitant arrhythmic surgery. Consequently, five and four patients in t-FC and p-FC groups required pacemaker implantations mostly due to sinus node dysfunction. Thromboembolism was seen in 2 cases in both t-FC (15%) and p-FC (13%), and 1 case in pTCPC (4%) (p = 0.50). The last cardiac catheterization was performed at the age of 29.5 ± 8.5, 24.6 ± 3.8, and 26.3 ± 7.1 years (p = 0.11) in t-FC, p-FC, and pTCPC patients, respectively. There was no significant difference in central venous pressure, aortic pressure, and cardiac index among the three groups. There was no late supraventricular tachyarrhythmic event seen in t-FC and p-FC, whereas two patients in pTCPC had newly developed atrial flutter. CONCLUSIONS: FC is a safe and feasible procedure to bring APC patients back onto the same track of primary TCPC patients in terms of hemodynamics as well as arrhythmia. The antiarrhythmic procedure should be carefully chosen because sinus node dysfunction can frequently occur and FC itself would reduce the risk of arrhythmia.


Assuntos
Técnica de Fontan , Cardiopatias Congênitas , Marca-Passo Artificial , Arritmias Cardíacas/etiologia , Cardiopatias Congênitas/cirurgia , Humanos , Artéria Pulmonar/cirurgia , Síndrome do Nó Sinusal
14.
Gen Thorac Cardiovasc Surg ; 69(3): 542-545, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32926389

RESUMO

We report the long-term clinical outcome of an 8-month-old infant who underwent tricuspid reconstruction using fresh autologous pericardium for severe tricuspid regurgitation due to defects in the leaflets of the tricuspid valve after ventricular septal defect closure and ablation. Ten years after surgery, the tricuspid function is good with mild regurgitation and mild stenosis. From the age of 8 months to 11 years, the patient's body weight and height increased fourfold and twofold, respectively. Thus, a fresh autologous pericardial patch could be the material of choice for tricuspid leaflet repair in pediatric patients.


Assuntos
Comunicação Interventricular , Insuficiência da Valva Tricúspide , Humanos , Lactente , Pericárdio/transplante , Valva Tricúspide/diagnóstico por imagem , Valva Tricúspide/cirurgia , Insuficiência da Valva Tricúspide/diagnóstico por imagem , Insuficiência da Valva Tricúspide/cirurgia
15.
Asian Cardiovasc Thorac Ann ; 29(6): 555-557, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33231480

RESUMO

A 7-year-old boy with a history of neonatal pulmonary artery banding underwent almost complete closure of a sieve-like "Swiss-cheese" ventricular septal defect, using a combination sandwich patch technique through a right ventriculotomy. Although defects existed in the high-, mid-, and low-trabecular septa, a right ventriculotomy and division of the muscle trabeculations continuing the septal and moderator bands helped delineate the edges of the defects. Although patients with "Swiss-cheese" ventricular septal defects may be candidates for a Fontan operation conventionally, a combination patch technique could be considered the procedure of choice.


Assuntos
Procedimentos Cirúrgicos Cardíacos , Comunicação Interventricular , Septo Interventricular , Criança , Comunicação Interventricular/diagnóstico por imagem , Comunicação Interventricular/cirurgia , Ventrículos do Coração , Humanos , Recém-Nascido , Masculino
16.
Inorg Chem ; 59(24): 18305-18313, 2020 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-33300332

RESUMO

We have synthesized inverse-perovskite-type oxysilicides and oxygermanides represented by R3SiO and R3GeO (R = Ca and Sr) and studied their characteristics in the search for nontoxic narrow band gap semiconductors. These compounds exhibit a sharp absorption edge around 0.9 eV and a luminescence peak in the same energy range. These results indicate that the obtained materials have a direct-band electronic structure, which was confirmed by hybrid DFT calculations. These materials, made from earth abundant and nontoxic elements and with a relatively light electron/hole effective mass, represent strong candidates for nontoxic optoelectronic devices in the infrared range.

17.
ACS Appl Mater Interfaces ; 12(36): 40495-40509, 2020 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-32786251

RESUMO

A novel UV-Vis photodetector consisting of an octahedral molybdenum cluster-functionalized Zn2Al layered double hydroxide (LDH) has been successfully synthesized by co-precipitation and delamination methods under ambient conditions. The electrophoretic deposition process has been used as a low-cost, fast, and effective method to fabricate thin and transparent nanocomposite films containing a dense and regular layered structure. The study provided evidence that the presence of the Mo6 cluster units between the LDH does not affect the ionic conduction mechanism of the LDH, which linearly depends on the relative humidity and temperature. Moreover, the photocurrent response is remarkably extended to the visible domain. The reproducibility and stabilization of the photocurrent response caused by the Mo6 cluster-functionalized LDH have been verified upon light excitation at 540 nm. Additionally, it was demonstrated that the films show advantageously strong adherence properties for application requirements.

18.
Int Heart J ; 61(1): 83-88, 2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-31956134

RESUMO

Percutaneous occlusion of atrial septal defect (ASD) has recently become a standard therapeutic strategy, but little is known about left atrial (LA) function thereafter. The present study aimed to determine LA function in 43 children with ASD and 13 controls based on LA strain measured by two-dimensional echocardiographic speckle tracking (2DE-ST). Among these children, 12 underwent surgery (ASD-S), 31 had device closure (ASD-D), and 13 were included as controls. LA strain was significantly decreased after ASD-D but was not significantly altered after ASD-S, indicating that percutaneous occlusion of an ASD might decrease LA function. Furthermore, the size of the ASD device negatively correlated with LA strain. These results imply that ASD occlusion devices negatively influence LA function and might be important when decided therapeutic strategies for ASD. LA strain measured by 2DE-ST should become a good indicator of LA function after ASD treatment in children.


Assuntos
Átrios do Coração/diagnóstico por imagem , Comunicação Interatrial/diagnóstico por imagem , Comunicação Interatrial/cirurgia , Função do Átrio Esquerdo , Procedimentos Cirúrgicos Cardíacos , Estudos de Casos e Controles , Criança , Ecocardiografia , Feminino , Átrios do Coração/fisiopatologia , Comunicação Interatrial/fisiopatologia , Humanos , Masculino , Estudos Retrospectivos , Resultado do Tratamento
19.
Chem Commun (Camb) ; 56(9): 1385-1388, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31912062

RESUMO

We investigated the multiscale characters of the crystal structure of the oxynitride perovskite LaTiO2N. While X-ray diffraction results identified the average structure as being centrosymmetric, we detected a signature of unknown structural deformation. By viewing the local structure, we unveiled the formation of a polar structure at the nanoscale.

20.
J Phys Chem Lett ; 10(22): 6967-6972, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31645099

RESUMO

Formamidinium [FA, HC(NH2)2+] lead iodide and its cation mixture have attracted interest as potentials in applications for efficient solar cells superior to well-known methylammonium lead iodide. We investigated the crystal structure and thermodynamic properties of high-quality single crystals of FA1-xCsxPbI3 for x = 0 and 0.1 through X-ray diffraction and heat capacity measurements. Both α-FA0.9Cs0.1PbI3 as well as α-FAPbI3 crystallize in a cubic Pm3̅m structure with orientationally disordered FA molecules confined in the nondistorted Pb-I framework. In FAPbI3, we observed a second-order transition at 280 K and two first-order transitions at 141.2 and 130.2 K in between ß- and γ-phases instead of the previously known single ß-γ transition. After doping with 10% Cs, the multiple first-order transitions disappeared, leading to phase transitions emerging at 300 and 149 K with second-order character. We moreover observed low-energy localized modes for both compounds, which is presumably tied to anomalous thermal motion, rattling, of the FA molecule.

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