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1.
Int J Antimicrob Agents ; 64(2): 107216, 2024 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-38795926

RESUMEN

The emergence of multidrug-resistant pathogens has outpaced the development of new antibiotics, leading to renewed interest in endolysins. Endolysins have been investigated as novel biocontrol agents for Gram-positive bacteria. However, their efficacy against Gram-negative species is limited by the barrier presented by their outer membrane, which prevents endolysin access to the peptidoglycan substrate. Here, we used the translocation domain of botulinum neurotoxin to deliver endolysin across the outer membrane of Gram-negative bacteria. The translocation domain selectively interacts with and penetrates membranes composed of anionic lipids, which have been used in nature to deliver various proteins into animal cells. In addition to the botulinum neurotoxin translocation domain, we have fused bacteriophage-derived receptor binding protein to endolysins. This allows the attached protein to efficiently bind to a broad spectrum of Gram-negative bacteria. By attaching these target-binding and translocation machineries to endolysins, we aimed to develop an engineered endolysin with broad-spectrum targeting and enhanced antibacterial activity against Gram-negative species. To validate our strategy, we designed engineered endolysins using two well-known endolysins, T5 and LysPA26, and tested them against 23 strains from six species of Gram-negative bacteria, confirming that our machinery can act broadly. In particular, we observed a 2.32 log reduction in 30 min with only 0.5 µM against an Acinetobacter baumannii isolate. We also used the SpyTag/SpyCatcher system to easily attach target-binding proteins, thereby improving its target-binding ability. Overall, our newly developed endolysin engineering strategy may be a promising approach to control multidrug-resistant Gram-negative bacterial strains.

2.
Inorg Chem ; 63(2): 1414-1426, 2024 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-38166391

RESUMEN

Reevaluating the composition of the double metal cyanide catalyst (DMC) as a salt of (NC)6Co3- anions with 1:1 Zn2+/(X)Zn+ cations (X = Cl, RO, AcO), we prepared a series of well-defined DMCs, [ClZn+][Zn2+][(NC)6Co3-][ROH], [(RO)Zn+][Zn2+][(NC)6Co3-], [(AcO)Zn+][Zn2+][(NC)6Co3-], [(RO)Zn+]p[ClZn+](1-p)[Zn2+][(NC)6Co3-], [(AcO)Zn+]p[(tBuO)Zn+]q[Zn2+][(NC)6Co3-], and [(AcO)Zn+]p[(tBuO)Zn+]q[ClZn+]r[Zn2+][(NC)6Co3-]. The structure of [(MeOC3H6O)Zn+][Zn2+][(NC)6Co3-] was precisely determined at the atomic level through Rietveld refinement of the synchrotron X-ray powder diffraction data. By evaluating the catalyst's performance in both propylene oxide (PO) polymerization and PO/CO2 copolymerization, a correlation between structure and performance was established on various aspects including activity, dispersity, unsaturation level, and carbonate fraction in the resulting polyols. Ultimately, our study identified highly efficient catalysts that outperformed the state-of-the-art benchmark DMC not only in PO polymerization [DMC-(OAc/OtBu/Cl)(0.59/0.38/0.15)] but also in PO/CO2 copolymerization [DMC-(OAc/OtBu)(0.95/0.08)].

3.
Int J Mol Sci ; 24(19)2023 Sep 28.
Artículo en Inglés | MEDLINE | ID: mdl-37834109

RESUMEN

Melanogenesis, the intricate process of melanin synthesis, is central to skin pigmentation and photoprotection and is regulated by various signaling pathways and transcription factors. To develop potential skin-whitening agents, we used B16F1 melanoma cells to investigate the inhibitory effects of anhydrous alum on melanogenesis and its underlying molecular mechanisms. Anhydrous alum (KAl(SO4)2) with high purity (>99%), which is generated through the heat-treatment of hydrated alum (KAl(SO4)2·12H2O) at 400 °C, potentiates a significant reduction in melanin content without cytotoxicity. Anhydrous alum downregulates the master regulator of melanogenesis, microphthalmia-associated transcription factor (MITF), which targets key genes involved in melanogenesis, thereby inhibiting α-melanocyte-stimulating hormone (α-MSH)-induced melanogenesis. Phosphorylation of the cAMP response element-binding protein, which acts as a co-activator of MITF gene expression, is attenuated by anhydrous alum, resulting in compromised MITF transcription. Notably, anhydrous alum promoted extracellular signal-regulated kinase phosphorylation, leading to the impaired nuclear localization of MITF. Overall, these results demonstrated the generation and mode of action of anhydrous alum in B16F1 cells, which constitutes a promising option for cosmetic or therapeutic use.


Asunto(s)
Melaninas , alfa-MSH , Melaninas/metabolismo , alfa-MSH/metabolismo , Monofenol Monooxigenasa/metabolismo , Factor de Transcripción Asociado a Microftalmía/genética , Factor de Transcripción Asociado a Microftalmía/metabolismo , Línea Celular Tumoral
4.
Int J Mol Sci ; 24(8)2023 Apr 21.
Artículo en Inglés | MEDLINE | ID: mdl-37108832

RESUMEN

The efficiency of plasma surface modifications depends on the operating conditions. This study investigated the effect of chamber pressure and plasma exposure time on the surface properties of 3Y-TZP with N2/Ar gas. Plate-shaped zirconia specimens were randomly divided into two categories: vacuum plasma and atmospheric plasma. Each group was subdivided into five subgroups according to the treatment time: 1, 5, 10, 15, and 20 min. Following the plasma treatments, we characterized the surface properties, including wettability, chemical composition, crystal structure, surface morphology, and zeta potential. These were analyzed through various techniques, such as contact angle measurement, XPS, XRD, SEM, FIB, CLSM, and electrokinetic measurements. The atmospheric plasma treatments increased zirconia's electron donation (γ-) capacity, while the vacuum plasma treatments decreased γ- parameter with increasing times. The highest concentration of the basic hydroxyl OH(b) groups was identified after a 5 min exposure to atmospheric plasmas. With longer exposure times, the vacuum plasmas induce electrical damage. Both plasma systems increased the zeta potential of 3Y-TZP, showing positive values in a vacuum. In the atmosphere, the zeta potential rapidly increased after 1 min. Atmospheric plasma treatments would be beneficial for the adsorption of oxygen and nitrogen from ambient air and the generation of various active species on the zirconia surface.


Asunto(s)
Presión Atmosférica , Circonio , Cerámica/química , Ensayo de Materiales , Propiedades de Superficie , Humectabilidad , Itrio , Circonio/química
5.
Materials (Basel) ; 15(24)2022 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-36556732

RESUMEN

Residual oxygen in wurtzite-type aluminum nitride (AlN) crystal, which significantly affects phonon transport and crystal growth, is crucial to thermal conductivity and the crystal quality of AlN ceramics. In this study, the effect of residual oxygen on the lattice of AlN was examined for as-synthesized and sintered samples. By controlling reaction time in the carbothermal reduction nitridation (CRN) procedure, AlN powder was successfully synthesized, and the amount of residual oxygen was systematically controlled. The evolution of lattice parameters of AlN with respect to oxygen conc. was carefully investigated via X-ray diffraction analysis. With increasing amounts of residual oxygen in the as-synthesized AlN, lattice expansion in the ab plane was induced without a significant change in the c-axis lattice parameter. The lattice expansion in the ab plane owing to the residual oxygen was also confirmed with high-resolution transmission electron microscopy, in contrast to the invariant lattice parameter of the sintered AlN phase. Micro-strain values from XRD peak broadening confirm that stress, induced by residual oxygen, expands the AlN lattice. In this work, the lattice expansion of AlN with increasing residual oxygen was elucidated via X-ray diffraction and HR-TEM, which is useful to estimate and control the lattice oxygen in AlN ceramics.

6.
J Microbiol Biotechnol ; 32(11): 1471-1478, 2022 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-36437520

RESUMEN

2'-Fucosyllactose (2'-FL), the most abundant fucosylated oligosaccharide in human milk, has multiple beneficial effects on human health. However, its biosynthesis by metabolically engineered Escherichia coli is often hampered owing to the insolubility and instability of α-1,2-fucosyltransferase (the rate-limiting enzyme). In this study, we aimed to enhance 2'-FL production by increasing the expression of soluble α-1,2-fucosyltransferase from Helicobacter pylori (FucT2). Because structural information regarding FucT2 has not been unveiled, we decided to improve the expression of soluble FucT2 in E. coli via directed evolution using a protein solubility biosensor that links protein solubility to antimicrobial resistance. For such a system to be viable, the activity of kanamycin resistance protein (KanR) should be dependent on FucT2 solubility. KanR was fused to the C-terminus of mutant libraries of FucT2, which were generated using a combination of error-prone PCR and DNA shuffling. Notably, one round of the directed evolution process, which consisted of mutant library generation and selection based on kanamycin resistance, resulted in a significant increase in the expression level of soluble FucT2. As a result, a batch fermentation with the ΔL M15 pBCGW strain, expressing the FucT2 mutant (F#1-5) isolated from the first round of the directed evolution process, resulted in the production of 0.31 g/l 2'-FL with a yield of 0.22 g 2'-FL/g lactose, showing 1.72- and 1.51-fold increase in the titer and yield, respectively, compared to those of the control strain. The simple and powerful method developed in this study could be applied to enhance the solubility of other unstable enzymes.


Asunto(s)
Escherichia coli , Fucosiltransferasas , Humanos , Fucosiltransferasas/genética , Resistencia a la Kanamicina , Escherichia coli/genética , Trisacáridos
7.
Int J Mol Sci ; 23(6)2022 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-35328427

RESUMEN

Plasma surface treatment can be an attractive strategy for modifying the chemically inert nature of zirconia to improve its clinical performance. This study aimed to clarify the effect of plasma gas compositions on the physicochemical surface modifications of 3 mol% yttria-stabilized zirconia (3Y-TZP). The cold, atmospheric plasma discharges were carried out by using four different plasma gases, which are He/O2, N2/Ar, N2, and Ar from an application distance of 10 mm for 60 s. Static contact angles were measured to define the surface free energy. Changes in elemental composition, surface crystallinity, and surface topography were assessed with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM), respectively. A significant decrease in water contact angle was observed in all plasma groups with the lowest value of 69° in the N2/Ar group. CLSM and SEM investigations exhibited no morphological changes in all plasma groups. XPS revealed that a reduction in the surface C content along with an increase in O content was pronounced in the case of N2/Ar compared to others, which was responsible for high hydrophilicity of the surface. XRD showed that the changes in crystallite size and microstrain due to oxygen atom displacements were observed in the N2/Ar group. The N2/Ar plasma treatment may contribute to enhancing the bioactivity as well as the bonding performance of 3Y-TZP by controlling the plasma-generated nitrogen functionalities.


Asunto(s)
Gases em Plasma , Itrio , Cerámica/química , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Propiedades de Superficie , Difracción de Rayos X , Itrio/química , Circonio/química
8.
Enzyme Microb Technol ; 153: 109914, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34670187

RESUMEN

Directed evolution is widely used to optimize protein folding and solubility in cells. Although the screening and selection of desired mutants is an essential step in directed evolution, it generally requires laborious optimization and/or specialized equipment. With a view toward designing a more practical procedure, we previously developed an inducible plasmid display system, in which the intein (auto-processing) and Oct-1 DNA-binding (DBD) domains were used as the protein trans-splicing domain and DNA-binding module, respectively. Specifically, the N-terminal (CfaN) and C-terminal (CfaC) domains of intein were fused to the C-terminal end of the His-tag and the N-terminal end of Oct-1 DBD to generate His6-CfaN and CfaC-Oct-1, respectively. For such a system to be viable, the efficiency of protein trans-splicing without the protein of interest (POI) should be maximized, such that the probability of occurrence is solely dependent on the solubility of the POI. To this end, we initially prevented the degradation of l-arabinose (the inducer of the PBAD promoter) by employing an Escherichia coli host strain deficient in the metabolism of l-arabinose. Given that a low expression of His6-CfaN, compared with that of CfaC-Oct-1, was found to be conducive to the generation to a soluble product of the protein trans-splicing event, we designed the expression of His6-CfaN and CfaC-Oct-1 to be inducible from the PBAD and PT7 promoters, respectively. The optimized system thus obtained enabled in vitro selection of the plasmid-protein complex with high yield. We believe that the inducible plasmid display system developed in this study would be applicable to high-throughput screening and/or selection of protein variants with enhanced solubility.


Asunto(s)
Ensayos Analíticos de Alto Rendimiento , Trans-Empalme , Plásmidos/genética
9.
Materials (Basel) ; 14(18)2021 Sep 16.
Artículo en Inglés | MEDLINE | ID: mdl-34576556

RESUMEN

Although sandblasting is mainly used to improve bonding between dental zirconia and resin cement, the details on the in-depth damages are limited. The aim of this study was to evaluate phase transformations and subsurface changes after sandblasting in three different dental zirconia (3, 4, and 5 mol% yttria-stabilized zirconia; 3Y-TZP, 4Y-PSZ, and 5Y-PSZ). Zirconia specimens (14.0 × 14.0 × 1.0 mm3) were sandblasted using different alumina particle sizes (25, 50, 90, 110, and 125 µm) under 0.2 MPa for 10 s/cm2. Phase transformations and residual stresses were investigated using X-ray diffraction and the Williamson-Hall method. Subsurface damages were evaluated with cross-sections by a focused ion beam. Stress field during sandblasting was simulated by the finite element method. The subsurface changes after sandblasting were the emergence of a rhombohedral phase, micro/macro cracks, and compressive/tensile stresses depending on the interactions between blasting particles and zirconia substrates. 3Y-TZP blasted with 110-µm particles induced the deepest transformed layer with the largest compressive stress. The cracks propagated parallel to the surface with larger particles, being located up to 4.5 µm under the surface in 4Y- or 5Y-PSZ subgroups. The recommended sandblasting particles were 110 µm for 3Y-TZP and 50 µm for 4Y-PSZ or 5Y-PSZ for compressive stress-induced phase transformations without significant subsurface damages.

10.
J Hazard Mater ; 398: 122857, 2020 11 05.
Artículo en Inglés | MEDLINE | ID: mdl-32512442

RESUMEN

Unique chemical and thermal stabilities of a zirconium-based metal-organic framework (MOF) and its functionalized analogues play a key role to efficiently remove chemical warfare agents (ex., cyanogen chloride, CNCl) and simulant (dimethyl methylphosphonate, DMMP) as well as industrial toxic gas, ammonia (NH3). Herein, we for the first time demonstrate outstanding performance of MOF-808 for removal of toxic chemicals in humid environment via special design of functionalization of hydroxo species bridging Zr-nodes using a triethylenediamine (TEDA) to form ionic frameworks by gas phase acid-base reactions. In situ experimental analyses and first-principles density functional theory calculations unveil underlying mechanism on the selective deposition of TEDA on the Zr-bridging hydroxo sites (µ3-OH) in Zr-MOFs. The crystal structure of TEDA-grafted MOF-808 was confirmed using synchrotron X-ray powder diffraction (SXRPD). Furthermore, operando FT-IR spectra elucidate why the TEDA-grafted MOF-808 shows by far superior sorption efficiency to other MOF varieties. This work provides design principles and applications how to optimize MOFs for the preparation for versatile adsorbents using diamine grafting chemistry, which is also potentially applicable to various catalysis.

11.
Materials (Basel) ; 13(8)2020 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-32326554

RESUMEN

Ba2SiO4-δN2/3δ:Eu2+ (BSON:Eu2+) materials with different N3- contents were successfully prepared and characterized. Rietveld refinements showed that N3- ions were partially substituted for the O2- ions in the SiO4-tetrahedra because the bond lengths of Si‒(O,N) (average value = 1.689 Å) were slightly elongated compared with those of Si‒O (average value = 1.659 Å), which resulted in the minute compression of the Ba(2)‒O bond lengths from 2.832 to 2.810 Å. The average N3- contents of BSON:Eu2+ phosphors were determined from 100 nm to 2000 nm depth of grain using a secondary ion mass spectrometry (SIMS): 0.064 (synthesized using 100% α-Si3N4), 0.035 (using 50% α-Si3N4 and 50% SiO2), and 0.000 (using 100% SiO2). Infrared (IR) and X-ray photoelectron spectroscopy (XPS) measurements corroborated the Rietveld refinements: the new IR mode at 850 cm-1 (Si‒N stretching vibration) and the binding energy at 98.6 eV (Si-2p) due to the N3- substitution. Furthermore, in UV-region, the absorbance of N3--substituted BSON:Eu2+ (synthesized using 100% α-Si3N4) phosphor was about two times higher than that of BSO:Eu2+ (using 100% SiO2). Owing to the N3- substitution, surprisingly, the photoluminescence (PL) and LED-PL intensity of BSON:Eu2+ (synthesized using 100% α-Si3N4) was about 5.0 times as high as that of BSO:Eu2+ (using 100% SiO2). The compressive strain estimated by the Williamson-Hall (W-H) method, was slightly increased with the higher N3- content in the host-lattice of Ba2SiO4, which warranted that the N3- ion plays an important role in the highly enhanced PL intensity of BSON:Eu2+ phosphor. These phosphor materials could be a bridgehead for developing new phosphors and application in white NUV-LEDs field.

12.
ACS Omega ; 4(5): 8431-8440, 2019 May 31.
Artículo en Inglés | MEDLINE | ID: mdl-31459932

RESUMEN

The N3--substituted Li2MSiO4:Eu2+ (M = Ca, Sr, and Ba) phosphors were systematically prepared and analyzed. Secondary-ion mass spectroscopy measurements revealed that the average N3- contents are 0.003 for Ca, 0.009 for Sr, and 0.032 for Ba. Furthermore, the N3- incorporation in the host lattices was corroborated by infrared and X-ray photoelectron spectroscopies. From the photoluminescence spectra of Li2MSiO4:Eu2+ (M = Ca, Sr, and Ba) phosphors before and after N3- doping, it was verified that the enhanced emission intensity of the phosphors is most likely due to the N3- doping. In Li2MSiO4:Eu2+ (M = Ca, Sr, and Ba) phosphors, the maximum wavelengths of the emission band were red-shifted in the order Ca < Ba < Sr, which is not consistent with the trend of crystal field splitting: Ba < Sr < Ca. This discrepancy was clearly explained by electron-electron repulsions among polyhedra, LiO4-MO n , SiO4-MO n , and MO n -M'O n associated with structural difference in the host lattices. Therefore, the energy levels associated with the 4f65d energy levels of Eu2+ are definitely established in the following order: Li2CaSiO4:Eu2+ > Li2BaSiO4:Eu2+ > Li2SrSiO4:Eu2+. Furthermore, using the Williamson-Hall (W-H) method, the determined structural strains of Li2MSiO4:Eu2+ (M = Ca, Sr, and Ba) phosphors revealed that the increased compressive strain after N3- doping induces the enhanced emission intensity of these phosphors. White light-emitting diodes made by three N3--doped phosphors and a 365 nm emitting InGaN chip showed the (0.333, 0.373) color coordinate and high color-rendering index (R a = 83). These phosphor materials may provide a platform for development of new efficient phosphors in solid-state lighting field.

13.
Phys Chem Chem Phys ; 21(4): 1737-1749, 2019 Jan 23.
Artículo en Inglés | MEDLINE | ID: mdl-30623958

RESUMEN

Self-emitting blue and red EuOX (X = F, Cl, Br, and I) were successfully synthesized and characterized. Far-infrared and Raman measurements revealed that the vibration modes prominently reflected the Eu-O and Eu-X bond characters of these materials. X-ray photoelectron spectroscopy (XPS) of the red-emitting EuOX compounds showed that Eu exclusively existed as Eu3+, while in the blue-emitting EuOX, a mixed Eu3+/Eu2+ state was observed. For the red-emitting EuOX (X = F, Cl, and Br), the maximum wavelengths of the charge-transfer (CT) bands were red-shifted: F → Cl → Br (282, 320, and 330 nm for F, Cl, and Br, respectively). Using one-electron spin-polarized band structure calculations, it was verified that the red-shift of the CT energy from F to Br in EuOX was mainly due to the relative positions of the halogen orbital energies being gradually increased, following the trend in their electronegativity. For the blue-emitting EuOX (X = Cl, Br, and I), the emission band maxima were red-shifted from Cl to I (409, 414, and 432 nm for Cl, Br, and I, respectively), which was quite opposite to the trend predicted based on the spectrochemical series in crystal field theory, which was in good agreement with the previous results of the calculated 5d → 4f transition energies of the Eu2+ activator based on the crystal field theory. Through photoluminescence, UV-visible absorbance, and XPS, it was elucidated that the red emission due to Eu3+ was strongly masked by the intensified blue emission associated with the small amount of Eu2+ in the blue-emitting EuOX (X = Cl, Br, and I). These materials may provide a platform for modeling new phosphors for application in solid-state lighting.

14.
Sci Rep ; 8(1): 5196, 2018 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-29563584

RESUMEN

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

15.
Sci Rep ; 7(1): 15984, 2017 11 22.
Artículo en Inglés | MEDLINE | ID: mdl-29167486

RESUMEN

Restricted lobar cerebral microbleeds (CMBs) and cortical superficial siderosis (CSS) are the characteristic markers of cerebral amyloid angiopathy (CAA). However, their effects on clinical features has not been evaluated well. The purpose of this study is to investigate the clinical implication of these markers in clinical-radiologically diagnosed CAA. A total of 372 patients with possible or probable CAA who met the modified Boston criteria were recruited in a memory clinic setting. Cortical thickness was measured using surface based methods. Presence of restricted multiple lobar CMBs were independently associated with cortical thinning across the entire cortical regions while presence of CSS was independently associated with cortical thinning primarily in the bilateral frontal region. Presence of restricted multiple lobar CMBs was associated with impairment in all cognitive domains such as attention, language, visuospatial, memory and frontal executive functions while presence of CSS was associated with attention and frontal dysfunction. The relationships of restricted multiple lobar CMBs or CSS with cognitive impairment were partially mediated by thinning in the corresponding cortical regions. Our findings suggested that restricted multiple lobar CMBs and CSS affect distinctive clinical features, providing new insights into potential mechanisms in CAA.


Asunto(s)
Encéfalo/fisiopatología , Angiopatía Amiloide Cerebral/fisiopatología , Hemorragia Cerebral/fisiopatología , Anciano , Anciano de 80 o más Años , Corteza Cerebral/fisiología , Disfunción Cognitiva/fisiopatología , Función Ejecutiva/fisiología , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino
16.
Nanoscale ; 9(43): 17144, 2017 11 09.
Artículo en Inglés | MEDLINE | ID: mdl-29077120

RESUMEN

Correction for 'Wafer-scale reliable switching memory based on 2-dimensional layered organic-inorganic halide perovskite' by Ja-Young Seo, et al., Nanoscale, 2017, DOI: 10.1039/c7nr05582j.

17.
Nanoscale ; 9(40): 15278-15285, 2017 10 19.
Artículo en Inglés | MEDLINE | ID: mdl-28994433

RESUMEN

Recently, organic-inorganic halide perovskite (OHP) has been suggested as an alternative to oxides or chalcogenides in resistive switching memory devices due to low operating voltage, high ON/OFF ratio, and flexibility. The most studied OHP is 3-dimensional (3D) MAPbI3. However, MAPbI3 often exhibits less reliable switching behavior probably due to the uncontrollable random formation of conducting filaments. Here, we report the resistive switching property of 2-dimensional (2D) OHP and compare switching characteristics depending on structural dimensionality. The dimensionality is controlled by changing the composition of BA2MAn-1PbnI3n+1 (BA = butylammonium, MA = methylammonium), where 2D is formed from n = 1, and 3D is formed from n = ∞. Quasi 2D compositions with n = 2 and 3 are also compared. Transition from a high resistance state (HRS) to a low resistance state (LRS) occurs at 0.25 × 106 V m-1 for 2D BA2PbI4 film, which is lower than those for quasi 2D and 3D. Upon reducing the dimensionality from 3D to 2D, the ON/OFF ratio significantly increases from 102 to 107, which is mainly due to the decreased HRS current. A higher Schottky barrier and thermal activation energy are responsible for the low HRS current. We demonstrate for the first time reliable resistive switching from 4 inch wafer-scale BA2PbI4 thin film working at both room temperature and a high temperature of 87 °C, which strongly suggests that 2D OHP is a promising candidate for resistive switching memory.

18.
Inorg Chem ; 56(20): 12116-12128, 2017 Oct 16.
Artículo en Inglés | MEDLINE | ID: mdl-28949134

RESUMEN

Blue-emitting Ca2-xMgxSiO4:Ce (0.0 ≤ x ≤ 1.0) phosphors were successfully synthesized and characterized. Rietveld refinement revealed that four main phases exist within the solid-solution range of CaO-MgO-SiO2, namely, ß-Ca2SiO4 (Mg (x) = 0.0), Ca14Mg2(SiO4)8 (Mg (x) = 0.25), Ca3Mg(SiO4)2 (Mg (x) = 0.5), and CaMgSiO4 (Mg (x) = 1.0). The variation of the IR modes was more prominent with increasing Mg2+ content in the Ca2-xMgxSiO4 materials. The sharing of O atoms of the SiO4-tetrahedra by the MgO6-octahedra induced weakening of the Si-O bonds, which resulted in the red shift of the [SiO4] internal modes and appearance of a Mg-O stretching vibration at ∼418 cm-1. Raman measurement revealed that the change of the Ca-O bond lengths because of the Mg2+-substitution directly reflected the frequency shift of the Si-O stretching-Raman modes. Notably, the thermal stability of Ca2-xMgxSiO4:Ce (Mg (x) > 0.0) phosphors was superior to that of ß-Ca2SiO4:Ce (Mg (x) = 0.0) as confirmed by temperature-dependent photoluminescence (PL) measurements. This indicated that Mg2+ ions play an important role in enhancement of the thermal stability. In combination with the results from PL and electroluminescence (EL), it was elucidated that the luminous efficiency of Ca2-xMgxSiO4:Ce (Mg (x) = 0.1) was approximately twice as much as ß-Ca2SiO4:Ce (Mg (x) = 0.00), directly indicating a "Mg2+-substitution effect". The large enhancements of PL, EL, and thermal stability because of Mg2+-substitution may provide a platform in the discovery of more efficient phosphors for NUV-LEDs.

19.
Physiother Can ; 69(3): 212-216, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-30275637

RESUMEN

Purpose: This article describes gluteus medius and minimus muscle thickness and hip abductor strength and function in healthy adults and explores the relationships between muscle thickness and function. Methods: Gluteus medius and minimus muscle thickness (B-mode ultrasound), isometric hip abductor strength (Biodex dynamometer), and lower extremity function (timed Trendelenburg test, Five-Times-Sit-to-Stand Test [FTSST], and lateral step-down test) were measured in healthy adults using a cross-sectional study design. Results: A total of 22 subjects were included: 10 men and 12 women, mean age 25.2 (SD 3.1) years, mean BMI 22.9 (SD 3.5) kilograms per metre squared. Muscle thickness of the gluteals was a mean 3.88 (SD 0.13) centimetres, and mean hip abductor peak torque was 111 (SD 43) newton-metres. FTSST mean time was 5.3 (SD 0.2) seconds, and median scores were 2.0 points for lateral step-down and 90 seconds for timed Trendelenburg. No significant relationships were found between gluteal muscle thickness and functional tests (rs=-0.28 to 0.37, ps=0.09-0.80) or strength (r=-0.24, p=0.28). Conclusion: Although hip abductors are key pelvic stabilizers for functional movements, gluteal muscle thickness was not associated with strength or function. This may be a result of agonist muscle activity, leading to an inability to isolate the gluteals, and to the ceiling effects of the functional tests.


Objectif : décrire l'épaisseur du muscle moyen glutéal et du muscle petit glutéal, la force et la fonction de l'abducteur de la hanche chez des adultes en santé et explorer les liens entre l'épaisseur et la fonction des muscles. Méthodologie : les chercheurs ont mesuré l'épaisseur du muscle moyen glutéal et du muscle petit glutéal (échographie en mode B), la force de l'abduction isométrique de la hanche (dynanomètre Biodex) et la fonction des jambes (test de Trendelenburg chronométré, test fonctionnel assis-debout de cinq répétitions [FTSST] et tests de descente latérale des marches) chez des adultes en santé dans le cadre d'une étude transversale. Résultats : au total, 22 sujets ont participé, soit 10 hommes et 12 femmes d'un âge moyen de 25,2 ans (ÉT 3,1 ans), d'un IMC moyen de 22,9 kg/m2 (ÉT 3,5 kg/m2). L'épaisseur moyenne des muscles glutéaux était de 3,88 cm (ÉT 0,13 cm), et la puissance de pointe moyenne de l'abducteur de la hanche, de 111 newton-mètres (ÉT 43 Nm). La durée moyenne du FTSST était de 5,3 secondes (ÉT 0,2 s), tandis que le score médian du test de descente latérale des marches était de 2,0 points, et celui du test de Trendelenburg chronométré, de 90 secondes. Il n'y avait pas de relation significative entre l'épaisseur des muscles glutéaux et les tests fonctionnels (r=−0,28 à +0,37, p=0,09 à 0,80) ou la force (r=−0,24, p=0,28). Conclusion : même si les abducteurs de la hanche sont des stabilisateurs essentiels du bassin lors des mouvements fonctionnels, l'épaisseur des muscles glutéaux ne s'associait ni à la force ni à la fonction. Ce peut être à cause de l'activité des muscles agonistes qui empêche d'isoler les muscles glutéaux, de même que des effets plafonds des tests fonctionnels.

20.
Ann Surg Treat Res ; 91(3): 112-7, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27617251

RESUMEN

PURPOSE: The aim of this study was to compare two methods of tumor localization during totally laparoscopic distal gastrectomy (TLDG) in patients with gastric cancer. METHODS: From March 2014 to November 2014, patients in whom TLDG had been engaged for middle third gastric cancer enrolled in this study. The patients were allocated to either the radiography or endoscopy group based on the type of tumor localization technique. Clinicopathologic outcomes were compared between the 2 groups. RESULTS: The accrual was suspended in November 2014 when 39 patients had been enrolled because a failed localization happened in the radiography group. The radiography and endoscopy groups included 17 (43.6 %) and 22 patients (56.4 %), respectively. Mean length of the proximal resection margin did not differ between the radiography and endoscopy groups (4.0 ± 2.6 and 2.8 ± 1.2 cm, respectively; P = 0.077). Mean localization time was longer in the radiography group than in the endoscopy group (22.7 ± 11.4 and 6.9 ± 1.8 minutes, respectively, P < 0.001). There were no statistically significant differences in the incidence of severe complications between the 2 groups (5.9% and 4.5%, respectively, P = 0.851). CONCLUSION: As an intraoperative tumor localization for TLDG, radiologic method was unsafe even though other comparable parameters were not different from that of endoscopy group. Moreover, intraoperative endoscopic localization may be advantageous because it is highly accurate and contributes to reducing operation time.

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