The precise modification of redox species on the inner and outer surfaces of hollow nanostructures is relevant in catalysis, surface science, and nanotechnology, but has proven difficult to achieve. ...Herein, we develop a facile approach to specifically fabricate Pt and Co3O4 nanoparticles (NPs) onto the interior and exterior surface of hollow carbon nitride spheres (HCNS), respectively, to promote the surface redox functions of the polymer semiconductors. The photocatalytic water splitting activities of HCNS with spatially separated oxidation and reduction centers at their nanodomains were enhanced. The origin of the enhanced activity was attributed to the spatially separated reactive sites for the evolution of H2 and O2 and also to the unidirectional migration of the electron and hole on the Janus surfaces, thereby preventing the unwanted reverse reaction of water splitting and decreasing charge recombination.
Interior design: A hollow conjugated carbon nitride semiconductor nanosphere with Pt and Co3O4 nanoparticles on the interior and exterior surfaces, respectively, has been prepared by a precise nanofabrication technology. The nanoparticle co‐catalysts enable the Janus hollow structure to photocatalyze water splitting by promoting charge separation and inhibiting the unwanted reverse reaction.
Carbon‐based catalysts have demonstrated great potential for the aerobic oxidative dehydrogenation reaction (ODH). However, its widespread application is retarded by the unavoidable deactivation ...owing to the appearance of coking or combustion under ODH conditions. The synthesis and characterization of porous structure of BCN nanosheets as well as their application as a novel catalyst for ODH is reported. Such BCN nanosheets consist of hybridized, randomly distributed domains of h‐BN and C phases, where C, B, and N were confirmed to covalent bond in the graphene‐like layers. Our studies reveal that BCN exhibits both high activity and selectivity in oxidative dehydrogenation of ethylbenzene to styrene, as well as excellent oxidation resistance. The discovery of such a simple chemical process to synthesize highly active BCN allows the possibility of carbocatalysis to be explored.
The porous structure of two‐dimension BCN nanosheets, consisting of hybridized h‐BN and C domains, were constructed for aerobic oxidative dehydrogenation reactions. The high porosity, novel pore structure, and abundant oxygen‐containing functional groups endow the BCN with more active sites.
Phthalates are a group of diesters of ortho‐phthalic acid (dialkyl or alkyl aryl esters of 1,2‐benzenedicarboxylic acid). Higher‐molecular‐weight phthalates, such as di‐2‐ethylhexyl phthalate (DEHP), ...are primarily used as plasticizers to soften polyvinyl chloride (PVC) products, while the lower‐molecular‐weight phthalates, such as diethyl phthalate (DEP), di‐n‐butyl phthalate (DBP), and butyl benzyl phthalate (BBzP), are widely used as solvents to hold color and scent in various consumer and personal care products. Phthalates have become ubiquitous environmental contaminants due to volatilization and leaching from their widespread applications, and thus contamination of the environment has become another important source for phthalates in foods in addition to migration from packaging materials. Human exposure to phthalates has been an increased concern due to the findings from toxicology studies in animals. DEHP, one of the important and widely used phthalates, is a rodent liver carcinogen. DEHP, DBP, BBzP, and several phthalate metabolites, such as monobutyl phthalate, monobenzyl phthalate, and mono‐(2‐ethylhexyl) phthalate, are teratogenic in animals. Since foods are the major source of exposure to phthalates, information on levels of phthalates in foods is important for human exposure assessment. The objective of this review is to identify the knowledge gaps for future investigations by reviewing levels of a wide range of phthalates in a variety of foods, such as bottled water, soft drinks, infant formula, human milk, total diet foods, and others, migration of phthalates from various food‐packaging materials, and traditional and new methodologies for the determination of phthalates in foods.
A probabilistic assessment is performed using different seismic fragility analysis approaches for structures under non-stationary stochastic ground motions. Four commonly used probabilistic seismic ...fragility analysis (PSFA) approaches are adopted, which are least squares regression (LSR), maximum likelihood estimation (MLE), kernel density estimation (KDE) and Monte Carlo simulation (MCS). The principles of the four PSFA approaches are first introduced, and the theories of non-stationary stochastic acceleration time series are introduced in light of the spectral representation of random functions. Then an analytical procedure of different PSFA approaches is constructed for structures under non-stationary stochastic motions. After that a case study is carried out to analyze the results of the four PSFA approaches. The demand distributions of univariate random variable under certain intensity measure levels are discussed, and multiple fragility curves under different limit states for all the approaches are compared. In general, the MCS approach is set as the benchmark to verify the effectiveness of other approaches, but it is computationally consuming. The non-parametric KDE approach is recommended to estimate the univariate distribution under specified IM levels, because it can reflect the real distribution characteristics with combined efficiency and accuracy. For the seismic fragility under different limit states, the LSR approach is suitable for efficient data processing and general trend assessment, at the expense of accuracy. The MLE approach indicates a better applicability under a smaller response threshold and slighter damage conditions, while the KDE approach shows a better applicability under a larger response threshold and severer damage conditions. The paper compares the accuracy and applicability of various PSFA approaches under multiple conditions, and provides a basis to link probabilistic hazard and risk analyses for performance assessment in the future research.
A consistent seismic hazard and fragility framework considering combined capacity-demand uncertainties is proposed, in light of the probability density evolution method (PDEM). The PDEM has solid ...theoretical basis in the reliability field, and it is integrated within the performance-based earthquake engineering (PBEE) for hazard-fragility assessment in this paper. During the analysis, the sample sets with different assigned probability are required to determine in advance, and the equivalent extreme events with virtual stochastic process are required to establish for solution. Both the uncertainties of capacity and demand are considered, and a combined performance index (CPI) is defined as concerned physical variable in PDEM, through pushover static and timehistory dynamic analyses. A non-stationary stochastic earthquake model is introduced using spectral representation of random functions, and the real characteristics of ground motions are reflected by one or two variables for each probability space. The peak ground acceleration (PGA) and spectral acceleration of the first period Sa(T1) of non-stationary stochastic ground motions are then obtained for each earthquake level, and the equivalent extreme events are also performed to discuss the statistical information of PGA or Sa(T1) through PDEM. The exceeding probability of PGA or Sa(T1) for each earthquake level is acquired, and a connection between the fragility value and hazard extent is built. The final 3D consistent hazard-fragility curves are then given, and the exceeding probability for different limit states, earthquake levels as well as intensity exceeding conditions can be predicted. Moreover, a comparison with the four classic approaches in the state-of-the-art is performed to verify the accuracy of PDEM procedure. In general, the framework avoids the pre-defined lognormal fragility shape and proves the combined efficiency and accuracy with the Monte Carlo simulation (MCS). The consistency from probabilistic hazard to fragility is realized without re-selecting earthquake waves, which is mainly attributed to the application of PDEM and non-stationary ground motions. The proposed framework provides new ideas for the consistent non-parametric hazard and fragility assessment scheme in the PBEE.
•Propose a consistent seismic hazard-fragility framework based on the PDEM and non-stationary stochastic earthquake.•Consider the combined capacity-demand uncertainties and a combined performance index with different assigned probability.•Give the 3D hazard-fragility curves incorporating different limit states, earthquake levels and intensity exceeding conditions.•Avoid the predefined lognormal curve shape and prove the combined efficiency and accuracy.
Summary
A new type of external substructure to upgrade existing reinforced concrete frames (RCFs) is presented in this paper, namely, a self‐centering precast bolt‐connected steel‐plate reinforced ...concrete buckling‐restrained brace frame (SC‐PBSPC BRBF). The upgrade mechanism and three‐dimensional simulation model were analyzed based on relevant experiment validations. A quasistatic analysis and parameter study was conducted using 21 scenarios to compare the upgrading effects of the outside substructure. Afterwards, a stiffness‐based design procedure was developed and modified for this external substructure, including macro‐demand analysis, partial component design, and overall structural evaluations. Dynamic analyses were also performed on a frame building for five cases, before and after strengthening. The proposed numerical model reflected the precast characteristics and displayed the ideal fitting accuracy. The external assembled brace provided sufficient initial stiffness and energy dissipation capacity, while the external prestressed tendon decreased residual displacements and facilitated self‐centering of the whole structure. The analyses illustrated that the damage to the existing RCF was transferred and seismic demands were significantly reduced within limitations, accompanied with greater capacity reliability. This research provides a reference for the practical applications of the external upgrading substructures in earthquake‐prone areas.
miR-190-5p in human diseases Yu, Yue; Cao, Xu-Chen
Cancer cell international,
10/2019, Letnik:
19, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
miRNAs, a major class of small noncoding RNAs approximately 18–25 nucleotides in length, function by repressing the expression of target genes through binding to complementary sequences in ...the 3′-UTRs of target genes. Emerging evidence has highlighted their important roles in numerous diseases, including human cancers. Recently, miR-190 has been shown to be dysregulated in various types of human cancers that participates in cancer-related biological processes, including proliferation, apoptosis, metastasis, drug resistance, by regulating associated target genes, and to predict cancer diagnosis and prognosis. In this review, we summarized the roles of miR-190-5p in human diseases, especially in human cancers. Then we classified its target genes in tumorigenesis and progression, which might provide evidence for cancer diagnosis and prognosis, promising tools for cancer treatment, or leads for further investigation.
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