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1.
Proc Natl Acad Sci U S A ; 121(9): e2319894121, 2024 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-38377200

RESUMEN

Nickel-iron oxy/hydroxides (NiFeOxHy) emerge as an attractive type of electrocatalysts for alkaline water oxidation reaction (WOR), but which encounter a huge challenge in stability, especially at industrial-grade large current density due to uncontrollable Fe leakage. Here, we tailor the Fe coordination by a MXene-mediated reconfiguration strategy for the resultant NiFeOxHy catalyst to alleviate Fe leakage and thus reinforce the WOR stability. The introduction of ultrafine MXene with surface dangling bonds in the electrochemical reconfiguration over Ni-Fe Prussian blue analogue induces the covalent hybridization of NiFeOxHy/MXene, which not only accelerates WOR kinetics but also improves Fe oxidation resistance against segregation. As a result, the NiFeOxHy coupled with MXene exhibits an extraordinary durability at ampere-level current density over 1,000 h for alkaline WOR with an ultralow overpotential of only 307 mV. This work provides a broad avenue and mechanistic insights for the development of nickel-iron catalysts toward industrial applications.

2.
Small ; : e2401226, 2024 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-38511543

RESUMEN

Electroredox of organics provides a promising and green approach to producing value-added chemicals. However, it remains a grand challenge to achieve high selectivity of desired products simultaneously at two electrodes, especially for non-isoelectronic transfer reactions. Here a porous heterostructure of Mo2C@Co-NC is successfully fabricated, where subnanometre ß-Mo2C clusters (<1 nm, ≈10 wt%) are confined inside porous Co, N-doped carbon using metalorganic frameworks. It is found that Co species not only promote the formation of ß-Mo2C but also can prevent it from oxidation by constructing the heterojunctions. As noted, the heterostructure achieves >96% yield and 92% Faradaic efficiency (FE) for aldehydes in anodic alcohol oxidation, as well as >99.9% yield and 96% FE for amines in cathodal nitrocompounds reduction in 1.0 M KOH. Precise control of the reaction kinetics of two half-reactions by the electronic interaction between ß-Mo2C and Co is a crucial adjective. Density functional theory (DFT) gives in-depth mechanistic insight into the high aldehyde selectivity. The work guides authors to reveal the electrooxidation nature of Mo2C at a subnanometer level. It is anticipated that the strategy will provide new insights into the design of highly effective bifunctional electrocatalysts for the coproduction of more complex fine chemicals.

3.
Org Biomol Chem ; 22(16): 3198-3203, 2024 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-38563151

RESUMEN

Novel construction methods for obtaining 3,4'-pyran spirooxindole heterocyclic skeletons have always been the focus of attention. Herein, we report a highly enantioselective inverse-electron-demand oxa-Diels-Alder cycloaddition reaction of a ß,γ-unsaturated pyrazole amide and a N-diphenyl isatin-derived oxodiene using a bifunctional catalyst. In addition, large-scale experiments confirmed the reliability of the reaction. The resultant products of this study can be further transformed.

4.
Cereb Cortex ; 33(18): 10194-10206, 2023 09 09.
Artículo en Inglés | MEDLINE | ID: mdl-37522301

RESUMEN

One of the clinical features of comitant strabismus is that the deviation angles in the first and second eye positions are equal. However, there has been no report of consistency in the electroencephalography (EEG) signals between the 2 positions. In order to address this issue, we developed a new paradigm based on perceptual eye position. We collected steady-state visual evoked potentials (SSVEPs) signals and resting-state EEG data before and after the eye position training. We found that SSVEP signals could characterize the suppression effect and eye position effect of comitant strabismus, that is, the SSVEP response of the dominant eye was stronger than that of the strabismus eye in the first eye position but not in the second eye position. Perceptual eye position training could modulate the frequency band activities in the occipital and surrounding areas. The changes in the visual function of comitant strabismus after training could also be characterized by SSVEP. There was a correlation between intermodulation frequency, power of parietal electrodes, and perceptual eye position, indicating that EEG might be a potential indicator for evaluating strabismus visual function.


Asunto(s)
Potenciales Evocados Visuales , Estrabismo , Humanos , Electroencefalografía , Estrabismo/terapia , Electrodos , Estimulación Luminosa
5.
Ecotoxicol Environ Saf ; 279: 116497, 2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38805827

RESUMEN

Methamphetamine (METH) is a highly abused substance on a global scale and has the capacity to elicit toxicity within the central nervous system. The neurotoxicity induced by METH encompasses neuronal degeneration and cellular demise within the substantia nigra-striatum and hippocampus. Caffeic acid phenethyl ester (CAPE), a constituent of propolis, is a diminutive compound that demonstrates antioxidative and anti-inflammatory characteristics. Numerous investigations have demonstrated the safeguarding effects of CAPE in various neurodegenerative ailments. Our hypothesis posits that CAPE may exert a neuroprotective influence on METH-induced neurotoxicity via specific mechanisms. In order to validate the hypothesis, a series of experimental techniques including behavioral tests, immunofluorescence labeling, RNA sequencing, and western blotting were employed to investigate the neurotoxic effects of METH and the potential protective effects of CAPE. The results of our study demonstrate that CAPE effectively ameliorates cognitive memory deficits and anxiety symptoms induced by METH in mice. Furthermore, CAPE has been observed to attenuate the upregulation of neurotoxicity-associated proteins that are induced by METH exposure and also reduced the loss of hippocampal neurons in mice. Moreover, transcriptomics analysis was conducted to determine alterations in gene expression within the hippocampus of mice. Subsequently, bioinformatics analysis was employed to investigate the divergent outcomes and identify potential key genes. Interferon-stimulated gene 15 (ISG15) was successfully identified and confirmed through RT-qPCR, western blotting, and immunofluorescence techniques. Our research findings unequivocally demonstrated the neuroprotective effect of CAPE against METH-induced neurotoxicity, with ISG15 may have an important role in the underlying protective mechanism. These results offer novel perspectives on the treatment of METH-induced neurotoxicity.


Asunto(s)
Ácidos Cafeicos , Metanfetamina , Fármacos Neuroprotectores , Síndromes de Neurotoxicidad , Alcohol Feniletílico , Animales , Ácidos Cafeicos/farmacología , Alcohol Feniletílico/análogos & derivados , Alcohol Feniletílico/farmacología , Metanfetamina/toxicidad , Fármacos Neuroprotectores/farmacología , Fármacos Neuroprotectores/uso terapéutico , Ratones , Masculino , Síndromes de Neurotoxicidad/prevención & control , Síndromes de Neurotoxicidad/tratamiento farmacológico , Hipocampo/efectos de los fármacos , Ratones Endogámicos C57BL , Neuronas/efectos de los fármacos
6.
Philos Trans A Math Phys Eng Sci ; 381(2244): 20220026, 2023 Apr 03.
Artículo en Inglés | MEDLINE | ID: mdl-36774958

RESUMEN

Viscoelastic shells subjected to a pressure loading exhibit rich and complex time-dependent responses. Here we focus on the phenomenon of pseudo-bistability, i.e. a viscoelastic shell can stay inverted when pressure is removed, and snap to its natural shape after a delay time. We model and explain the mechanism of pseudo-bistability with a viscoelastic shell model. It combines the small strain, moderate rotation shell theory with the standard linear solid as the viscoelastic constitutive law, and is applicable to shells with arbitrary axisymmetric shapes. As a case study, we investigate the pseudo-bistable behaviour of viscoelastic ellipsoidal shells. Using the proposed model, we successfully predict buckling of a viscoelastic ellipsoidal shell into its inverted configuration when subjected to an instantaneous pressure, creeping when the pressure is held, staying inverted after the pressure is removed, and eventually snapping back after a delay time. The stability transition of the shell from a monostable, temporarily bistable and eventually back to the monostable state is captured by examining the evolution of the instantaneous pressure-volume change relation at different time of the holding and releasing process. A systematic parametric study is conducted to investigate the effect of geometry, viscoelastic properties and loading history on the pseudo-bistable behaviour. This article is part of the theme issue 'Probing and dynamics of shock sensitive shells'.

7.
Bioorg Chem ; 133: 106432, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36841050

RESUMEN

Alzheimer's disease (AD) implicates neuronal loss, plaque and neurofibrillary tangle formation, and disturbed neuronal Ca2+ homeostasis, which leads to severe dementia, memory loss, as well as thinking and behavioral perturbations that could ultimately lead to death. Calcium dysregulation and low acetylcholine levels are two main mechanisms implicated in Alzheimer's disease progression. Simultaneous inhibition of calcium oscillations (store overload-induced Ca2+ release [SOICR]) and acetylcholinesterase (AChE) by a single molecule may bring a new breath of hope for AD treatment. Here, we described some dantrolene derivatives as dual inhibitors of the ryanodine receptor and AChE. Two series of acylhydrazone/sulfonylhydrazone derivatives with aromaticgroup were designed and synthesized. In this study, the target compounds were evaluated for their ability to inhibit SOICR and AChE in vitro, using dantrolene and donepezil as positive controls. Compound 22a exhibited excellent and balanced inhibitory potency against SOICR (inhibition (%) = 90.1, IC50 = 0.162 µM) and AChE (inhibition (%) = 93.5, IC50 = 0.372 µM). Docking simulations showed that several preferred compounds could bind to the active sites of both the proteins, further validating the rationality of the design strategy. Potential therapeutic effects in AD were evaluated using the Barnes maze and Morris water maze tests, which demonstrated that compound 22a significantly improved memory and cognitive behavior in AD model mice. Moreover, it was also found that compound 22a could enhance synaptic strength by measuring hippocampal long-term potentiation (LTP) in brain slices. These results suggested that the introduction of a sulfonyl-hydrazone scaffold and aromatic substitution to dantrolene derivatives provided a useful template for the development of potential chemical entities against AD.


Asunto(s)
Enfermedad de Alzheimer , Hidrazonas , Animales , Ratones , Acetilcolinesterasa/metabolismo , Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/metabolismo , Inhibidores de la Colinesterasa/farmacología , Inhibidores de la Colinesterasa/uso terapéutico , Inhibidores de la Colinesterasa/química , Dantroleno/farmacología , Dantroleno/uso terapéutico , Hidrazonas/química , Hidrazonas/farmacología , Simulación del Acoplamiento Molecular , Canal Liberador de Calcio Receptor de Rianodina/química , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Relación Estructura-Actividad
8.
Phytother Res ; 37(2): 464-476, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36608695

RESUMEN

Tenuifolin (TEN), a natural neuroprotective compound obtained from the Polygala tenuifolia Willd plant, has improved cognitive symptoms. However, the impact of TEN on memory impairments caused by sleep deprivation (SD) is unclear. Accordingly, the objective of this study was to investigate the mechanisms behind the preventative benefits of TEN on cognitive impairment caused by SD. TEN (10 and 20 mg/kg) and Huperzine A (0.1 mg/kg) were given to mice through oral gavage for 28 days during the SD process. The results indicate that TEN administrations improve short- and long-term memory impairments caused by SD in the Y-maze, object identification, and step-through tests. Moreover, TEN stimulated the generation of anti-inflammatory cytokines (interleukin-10), lowered the production of pro-inflammatory cytokines (interleukin-1ß, interleukin-6, and interleukin-18), and activated microglia, improving antioxidant status in the hippocampus. TEN treatments significantly boosted the expression of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 while considerably decreasing the expression of NOD-like receptor thermal protein domain associated protein 3 and caspase-1 p20. Additionally, TEN restored the downregulation of the brain-derived neurotrophic factor signaling cascade and the impaired hippocampal neurogenesis induced by SD. When considered collectively, our data suggest that TEN is a potentially effective neuroprotective agent for cognition dysfunction.


Asunto(s)
Disfunción Cognitiva , Privación de Sueño , Animales , Ratones , Cognición , Disfunción Cognitiva/tratamiento farmacológico , Citocinas/metabolismo , Hipocampo , Aprendizaje por Laberinto , Privación de Sueño/complicaciones , Privación de Sueño/tratamiento farmacológico
9.
J Gene Med ; 24(8): e3441, 2022 08.
Artículo en Inglés | MEDLINE | ID: mdl-35840542

RESUMEN

BACKGROUND: Synaptogyrin-2 (SYNGR2) plays an important role in regulating membrane traffic in non-neuronal cells. However, the role of SYNGR2 in esophageal squamous cell carcinoma (ESCC) remains unclear. METHODS: All original data were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases and integrated via R 3.5.3. SYNGR2 expression was explored in the TCGA and GEO databases. The correlations between SYNGR2 and cancer immune characteristics were analyzed via the TIMER and TISIDB databases. RESULTS: In general, SYNGR2 was predominantly overexpressed and had reference values in the diagnosis and prognostic estimation of ESCC. Upregulated SYNGR2 was associated with poorer overall survival, disease-specific survival and T stage in ESCC. Mechanistically, we identified hub genes that included a total of 38 SYNGR2-related genes, which were tightly associated with the protein polyubiquitination pathway in ESCC patients. SYNGR2 expression was negatively related to the infiltrating levels of T helper cells. SYNGR2 methylation was positively correlated with the expression of chemokines (CCL2 and CXCL12), chemokine receptors (CCR1 and CCR2), immunoinhibitors (CXCL12 and TNFRSF4) and immunostimulators (CSF1R and PDCD1LG2) in ESCC. CONCLUSION: SYNGR2 may be used as a biomarker for determining prognosis and immune infiltration in ESCC.


Asunto(s)
Neoplasias Esofágicas , Carcinoma de Células Escamosas de Esófago , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Neoplasias Esofágicas/diagnóstico , Neoplasias Esofágicas/genética , Carcinoma de Células Escamosas de Esófago/genética , Carcinoma de Células Escamosas de Esófago/patología , Regulación Neoplásica de la Expresión Génica , Humanos , Pronóstico
10.
Soft Matter ; 18(21): 4077-4089, 2022 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-35603603

RESUMEN

Formation of desired three-dimensional (3D) shapes from flat thin sheets with programmed non-uniform deformation profiles is an effective strategy to create functional 3D structures. Liquid crystal elastomers (LCEs) are of particular use in programmable shape morphing due to their ability to undergo large, reversible, and anisotropic deformation in response to a stimulus. Here we consider a rectangular monodomain LCE thin sheet divided into one high- and one low-temperature strip, which we dub a 'bistrip'. Upon activation, a discontinuously patterned, anisotropic in-plane stretch profile is generated, and induces buckling of the bistrip into a rolled shape with a transitional bottle neck. Based on the non-Euclidean plate theory, we derive an analytical model to quantitatively capture the formation of the rolled shapes from a flat bistrip with finite thickness by minimizing the total elastic energy involving both stretching and bending energies. Using this analytical model, we identify the critical thickness at which the transition from the unbuckled to buckled configuration occurs. We further study the influence of the anisotropy of the stretch profile on the rolled shapes by first converting prescribed metric tensors with different anisotropy to a unified metric tensor embedded in a bistrip of modified geometry, and then investigating the effect of each parameter in this unified metric tensor on the rolled shapes. Our analysis sheds light on designing shape morphing of LCE thin sheets, and provides quantitative predictions on the 3D shapes that programmed LCE sheets can form upon activation for various applications.

11.
Support Care Cancer ; 30(3): 2853-2876, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-34561732

RESUMEN

PURPOSE: To determine the effectiveness of mobile health-based self-management interventions on medical/behavioral, role, and emotional management in breast cancer patients. METHODS: The Embase, MEDLINE, SINOMED, the Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), WanFang, and Weipu (VIP) databases were extensively searched from inception to November 30, 2020, to identify eligible clinical trials. Outcomes included medical/behavioral management (self-management behavior, functional exercise compliance, self-efficacy, complications, and symptoms), role management (role functioning), and emotional management (anxiety and depression), social support, and health-related quality of life. RESULTS: Twenty-four studies were included in this meta-analysis. The results of the meta-analysis indicated that mobile health-based self-management interventions could potentially improve breast cancer patients' self-management behavior, functional exercise compliance (WMD = 15.80, 95% CI = 10.53 to 21.08, P < 0.001), self-efficacy (SMD = 1.22, 95% CI = 0.57 to 1.87, P < 0.001), and health-related quality of life (SMD = 0.78, 95% CI = 0.44 to 1.12, P < 0.001); reduce the incidence of lymphedema (RR = 0.20, 95% CI = 0.15 to 0.26, P < 0.001); and relieve the level of anxiety (SMD = - 0.67, 95% CI = - 0.99 to - 0.35, P < 0.001). However, patients assigned to the mobile health group and the conventional care group did not differ significantly in symptom relief (including pain and fatigue), role functioning, depression, or social support (all P ≥ 0.05). CONCLUSION: Mobile health-based self-management interventions can potentially facilitate the self-management and health-related quality of life of breast cancer patients.


Asunto(s)
Neoplasias de la Mama , Automanejo , Telemedicina , Ansiedad/epidemiología , Ansiedad/etiología , Neoplasias de la Mama/terapia , Depresión/epidemiología , Depresión/etiología , Depresión/terapia , Femenino , Humanos , Calidad de Vida
12.
Plant Cell Rep ; 41(12): 2321-2339, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36063182

RESUMEN

KEY MESSAGE: Five PeAOX genes from Moso bamboo genome were identified. PeAOX1b_2-OE improved tolerance to drought and salinity stress in Arabidopsis, indicating it is involved in positive regulation of abiotic stress response. Mitochondrial alternative oxidase (AOX), the important respiratory terminal oxidase in organisms, catalyzes the energy wasteful cyanide (CN)-resistant respiration, which can improve abiotic stresses tolerance and is considered as one of the functional markers for plant resistance breeding. Here, a total of five putative AOX genes (PeAOXs) were identified and characterized in a monocotyledonous woody grass Moso bamboo (Phyllostachys edulis). Phylogenetic analysis revealed that PeAOXs belonged to AOX1 subfamily, and were named PeAOX1a_1, PeAOX1a_2, PeAOX1b_1, PeAOX1b_2 and PeAOX1c, respectively. Evolutionary and divergence patterns analysis revealed that the PeAOX, OsAOX, and BdAOX families experienced positive purifying selection and may have undergone a large-scale duplication event roughly 1.35-155.90 million years ago. Additionally, the organ-specific expression analysis showed that 80% of PeAOX members were mainly expressed in leaf. Promoter sequence analysis of PeAOXs revealed cis-acting regulatory elements (CAREs) responding to abiotic stress. Most PeAOX genes were significantly upregulated after methyl jasmonate (MeJA) and abscisic acid (ABA) treatment. Moreover, under salinity and drought stresses, the ectopic overexpression of PeAOX1b_2 in Arabidopsis enhanced seed germination and seedling establishment, increased the total respiratory rate and the proportion of AOX respiratory pathway in leaf, and enhanced antioxidant ability, suggesting that PeAOX1b_2 is crucial for abiotic stress resistance in Moso bamboo.


Asunto(s)
Arabidopsis , Sequías , Regulación de la Expresión Génica de las Plantas/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Filogenia , Salinidad , Fitomejoramiento , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Poaceae/genética , Poaceae/metabolismo , Tolerancia a la Sal/genética , Oxidorreductasas/metabolismo
13.
Small ; 17(22): e2004481, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33458947

RESUMEN

Composite materials with multifunctional properties usually possess synergetic effects in catalysis toward cascade reactions. In this work, a facile strategy to the encapsulation of octahedral Cu2 O nanocrystals (NCs) by metal-organic frameworks (MOFs) is reported, and an oriented growth of MOF enclosures (namely, HKUST-1) around Cu2 O NCs with desired feedstock ratio is achieved. The strategy defines the parameter range that precisely controls the etching rate of metal oxide and the MOF crystallization rate. Finally, the Cu@HKUST-1 composites with uniform morphology and controlled MOF thickness have been successfully fabricated after the reduction of Cu2 O to Cu NCs in HKUST-1. The integration of Cu NCs properties with MOF advantages helps to create a multifunctional catalyst, which exhibits cooperative catalytic activity and improved recyclability toward the one-pot cascade reactions under mild conditions involving visible-light irradiation. The superior performance can be attributed to the plasmonic photothermal effect of Cu NCs, while HKUST-1 shell provides Lewis acid sites, substrates and H2 enrichment, and stabilizes the Cu cores.

14.
IEEE Sens J ; 21(9): 11084-11093, 2021 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-36820762

RESUMEN

Coronavirus Disease 2019 (COVID-19) has spread all over the world since it broke out massively in December 2019, which has caused a large loss to the whole world. Both the confirmed cases and death cases have reached a relatively frightening number. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of COVID-19, can be transmitted by small respiratory droplets. To curb its spread at the source, wearing masks is a convenient and effective measure. In most cases, people use face masks in a high-frequent but short-time way. Aimed at solving the problem that we do not know which service stage of the mask belongs to, we propose a detection system based on the mobile phone. We first extract four features from the gray level co-occurrence matrixes (GLCMs) of the face mask's micro-photos. Next, a three-result detection system is accomplished by using K Nearest Neighbor (KNN) algorithm. The results of validation experiments show that our system can reach an accuracy of 82.87% (measured by macro-measures) on the testing dataset. The precision of Type I 'normal use' and the recall of type III 'not recommended' reach 92.00% and 92.59%. In future work, we plan to expand the detection objects to more mask types. This work demonstrates that the proposed mobile microscope system can be used as an assistant for face mask being used, which may play a positive role in fighting against COVID-19.

15.
Psychol Health Med ; 26(1): 98-106, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33305600

RESUMEN

Impact of supportive interventions on resilience and self-assessed psychopathology symptoms of 92 nurses in isolation ward during the COVID-19 pandemic was evaluated. Resilience and psychopathological symptoms of nurses in the isolation ward was assessed by Connor-Davidson Resilience Scale (CD-RISC) and the Symptom Checklist 90 (SCL-90). A total resilience score was 87.04 ± 22.78. The SCL-90 score was 160- to 281 (202.5 ± 40.79). Only 8.70% of the nurses (n = 8) had a total SCL-90 score >160, suggesting positive symptoms. The majority of nurses had 0 to 90 positive self-assessment items (median 14); 19.57% (n = 18) had > 43 positive items. Interpersonal sensitivity, depression, hostility, and paranoid ideation scores were below national averages (p=0.000, 0.040, 0.002, 0.004, respectively). SCL-90 items reflecting diet and sleep conditions were higher(P = 0.009), and somatization, obsessive-compulsive, anxiety, phobic anxiety, and psychoticism domains and scores were similar to national averages (P>0.3). With exception of somatization and other domains, the mean resilience score was negatively associated with the scores of other SCL-90 domains. High resilience promotes physical and mental health, and may be improved by training, psychological interventions and full use of hospital resources.


Asunto(s)
COVID-19/enfermería , Departamentos de Hospitales/estadística & datos numéricos , Trastornos Mentales/epidemiología , Personal de Enfermería en Hospital/estadística & datos numéricos , Aislamiento de Pacientes , Resiliencia Psicológica , Adulto , Estudios Transversales , Femenino , Humanos , Masculino , Persona de Mediana Edad
16.
J Org Chem ; 85(19): 12175-12186, 2020 10 02.
Artículo en Inglés | MEDLINE | ID: mdl-32885968

RESUMEN

A highly enantioselective 1,4-addition reaction of azadiene with 3-homoacyl coumarin has been accomplished by low amounts of bifunctional cinchona alkaloid catalysis under mild conditions. Varieties of benzofuran coumarin skeletons were obtained in moderate to high yields (up to 99%) with excellent enantioselectivities (up to 99% ee) and complete diastereoselectivity.

17.
Langmuir ; 35(2): 372-381, 2019 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-30575374

RESUMEN

The electric actuation of room-temperature liquid metals, such as Galinstan (gallium-indium-tin), has largely been conducted in alkaline electrolyte. Addition of surface-active anions and a proper acidic pH are expected to influence the interfacial tension of the liquid metal due to a high surface charge density. Hence, it should be possible to actuate liquid metals in such acidic environments. To ascertain this, at first, the dependence of the interfacial tension of Galinstan in NaOH, acidified KI, and acidified NaCl electrolyte on the concentration of the surface-active anions OH-, I-, and Cl-, respectively, were studied. Subsequently, a systematic study of the actuation of Galinstan in acidified KI electrolyte was executed and compared to actuation in alkaline medium. In the presence of HCl and acidified NaCl electrolyte, the interfacial tension of Galinstan is only marginally altered, while acidified KI solution reduced the interfacial tension of Galinstan significantly from 470.8 ± 1.4 (no KI) to 370.6 ± 4.1 mN/m (5 M KI) due to the high surface charge density of the electric double layer. Therefore, in acidified electrolyte in the presence of surface-active anions, the electrically actuated motion of LM can be realized. In particular, the actuation of Galinstan achieves a higher average and maximum speed at lower applied voltage and power consumption for acidified KI electrolyte. The formation of high surface charge density in acidified environments signifies a paradigm shift and opens up new possibilities to tune interfacial tension and controlled LM droplet motion of room-temperature liquid metals.

18.
Org Biomol Chem ; 17(16): 3945-3950, 2019 04 17.
Artículo en Inglés | MEDLINE | ID: mdl-30942250

RESUMEN

An enantioselective [4 + 2] cyclization reaction of dioxopyrrolidines and azlactones has been successfully developed through a squaramide catalysis strategy. This protocol provides an efficient and mild access to obtain pyrano[2,3-c]pyrrole scaffolds containing contiguous quaternary and tertiary stereogenic centers in excellent yields (up to 99%) with high levels of diastereo- and enantioselectivities (up to 99% ee). Two possible pathways were proposed to explain the observed stereoselectivity.

19.
Chemphyschem ; 19(13): 1584-1592, 2018 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-29539243

RESUMEN

Room-temperature gallium-based liquid metals (e. g. Galinstan) are emerging materials for a wide range of applications spanning from soft robotics to a medium for running chemical reactions. However, Galinstan suffers from rapid oxide formation at the surface, limiting its application. Similarly, this surface oxidation renders it difficult to determine the surface free energy of Galinstan. Herein, the interfacial properties of Galinstan in contact with argon, acid, base, water, and organic solvents were investigated, yielding kinetic information regarding the removal by acids and bases, knowledge about oxo-hydroxide/hydroxide species at the Galinstan/water interface, and an estimated value of the dispersive contribution of the surface free energy. The dispersive contribution of the surface free energy of Galinstan was calculated to be (239.7±9.1) mN/m, around 40 % of the total surface free energy. By employing the dispersive surface tension of Galinstan, the interfacial tension between a liquid and Galinstan can be easily obtained, facilitating the design and application of liquid metal-based devices.

20.
Sensors (Basel) ; 18(11)2018 Nov 14.
Artículo en Inglés | MEDLINE | ID: mdl-30441788

RESUMEN

The influence of oxygen vacancy behaviors during a cooling process in semiconductor gas sensors is discussed by the numerical analysis method based on the gradient-distributed oxygen vacancy model. A diffusion equation is established to describe the behaviors of oxygen vacancies, which follows the effects of diffusion and exclusion in the cooling process. Numerical analysis is introduced to find the accurate solutions of the diffusion equation. The solutions illustrate the oxygen vacancy distribution profiles, which are dependent on the cooling rate as well as the temperature interval of the cooling process. The gas-sensing characteristics of reduced resistance and response are calculated. Both of them, together with oxygen vacancy distribution, show the grain size effects and the re-annealing effect. It is found that the properties of gas sensors can be controlled or adjusted by the designed cooling process. The proposed model provides a possibility for sensor characteristics simulations, which may be beneficial for the design of gas sensors. A quantitative interpretation on the gas-sensing mechanism of semiconductors has been contributed.

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