Showing papers by "China Three Gorges University published in 2018"

Metal-Organic Frameworks for Separation.

Abstract: Separation is an important industrial step with critical roles in the chemical, petrochemical, pharmaceutical, and nuclear industries, as well as in many other fields. Although much progress has been made, the development of better separation technologies, especially through the discovery of high-performance separation materials, continues to attract increasing interest due to concerns over factors such as efficiency, health and environmental impacts, and the cost of existing methods. Metal-organic frameworks (MOFs), a rapidly expanding family of crystalline porous materials, have shown great promise to address various separation challenges due to their well-defined pore size and unprecedented tunability in both composition and pore geometry. In the past decade, extensive research is performed on applications of MOF materials, including separation and capture of many gases and vapors, and liquid-phase separation involving both liquid mixtures and solutions. MOFs also bring new opportunities in enantioselective separation and are amenable to morphological control such as fabrication of membranes for enhanced separation outcomes. Here, some of the latest progress in the applications of MOFs for several key separation issues, with emphasis on newly synthesized MOF materials and the impact of their compositional and structural features on separation properties, are reviewed and highlighted.

Breast cancer development and progression: Risk factors, cancer stem cells, signaling pathways, genomics, and molecular pathogenesis.

Abstract: As the most commonly occurring cancer in women worldwide, breast cancer poses a formidable public health challenge on a global scale. Breast cancer consists of a group of biologically and molecularly heterogeneous diseases originated from the breast. While the risk factors associated with this cancer varies with respect to other cancers, genetic predisposition, most notably mutations in BRCA1 or BRCA2 gene, is an important causative factor for this malignancy. Breast cancers can begin in different areas of the breast, such as the ducts, the lobules, or the tissue in between. Within the large group of diverse breast carcinomas, there are various denoted types of breast cancer based on their invasiveness relative to the primary tumor sites. It is important to distinguish between the various subtypes because they have different prognoses and treatment implications. As there are remarkable parallels between normal development and breast cancer progression at the molecular level, it has been postulated that breast cancer may be derived from mammary cancer stem cells. Normal breast development and mammary stem cells are regulated by several signaling pathways, such as estrogen receptors (ERs), HER2, and Wnt/β-catenin signaling pathways, which control stem cell proliferation, cell death, cell differentiation, and cell motility. Furthermore, emerging evidence indicates that epigenetic regulations and noncoding RNAs may play important roles in breast cancer development and may contribute to the heterogeneity and metastatic aspects of breast cancer, especially for triple-negative breast cancer. This review provides a comprehensive survey of the molecular, cellular and genetic aspects of breast cancer.

A water-stable Tb(III)-based metal–organic gel (MOG) for detection of antibiotics and explosives

Abstract: The rapid detection of antibiotics and organic explosives has gradually garnered great attention, due to concerns about sustainability and the environment. In this work, a luminescent Tb-based metal organic gel (MOG(Tb) gel) was prepared by Al-based MOG induced in situ replacement of Al3+ with Tb3+. Remarkably, the strong emission of the post-synthesized MOG(Tb) xerogel can be quenched efficiently by using trace amounts of sulfamethazine (SMZ) and sulfadiazine (SDZ) even in the presence of other competing antibiotics. Furthermore, the MOG(Tb) xerogel has shown its application as a chemosensor for the highly selective detection of nitroaromatics such as 2,4-dinitrophenol (2,4-DNT) and 2,6-dinitrophenol (2,6-DNT). To further verify the recyclability of MOG(Tb), detection experiments were carried out with recovered xerogel to give a satisfactory result.

Synthesis and applications of graphene quantum dots: a review

Abstract: Abstract As a new class of fluorescent carbon materials, graphene quantum dots (GQDs) have attracted tremendous attention due to their outstanding properties and potential applications in biological, optoelectronic, and energy-related fields. Herein, top-down and bottom-up strategies for the fabrication of GQDs, mainly containing oxidative cleavage, the hydrothermal or solvothermal method, the ultrasonic-assisted or microwave-assisted process, electrochemical oxidation, controllable synthesis, and carbonization from small molecules or polymers, are discussed. Different methods are presented in order to study their characteristics and their influence on the final properties of the GQDs. The respective advantages and disadvantages of the methods are introduced. With regard to some important or novel methods, the mechanisms are proposed for reference. Moreover, recent exciting progresses on the applications of GQD, such as sensors, bio-imaging, drug carriers, and solar cells are highlighted. Finally, a brief outlook is given, pointing out the issues still to be settled for further development. We believe that new preparation methods and properties of GQDs will be found, and GQDs will play more important roles in novel devices and various applications.

In situ synthesis of n–n Bi2MoO6 & Bi2S3 heterojunctions for highly efficient photocatalytic removal of Cr(VI)

Abstract: Exploiting novel photocatalysts with high efficiency and durability for reduction of hexavalent chromium (Cr(VI)) has gained attention from fundamental science and industrial research. In this work, we synthesized novel two-dimensional (2D) n–n Bi2MoO6 & Bi2S3 heterojunctions by a facile in situ anion exchange process for remarkably efficient removal of Cr(VI). Results show that Bi2MoO6 & Bi2S3 heterojunctions with core–shell structures are formed through the intimate contact of Bi2MoO6 core and Bi2S3 shell. The prepared Bi2MoO6 & Bi2S3 heterojunctions exhibit unprecedented photocatalytic activity for reduction of Cr(VI) under visible light irradiation. The optimized BMO-S1 heterojunction displays the highest reduction efficiency (κapp = 0.164 min−1) for Cr(VI) reduction. To the best of our knowledge, it is one of the highest reduction rate achieved among reported photocatalysts for Cr(VI) reduction under visible-light irradiation. Detailed studies show that strong selective adsorption for Cr(VI) enhances this unprecedented photocatalytic activity. Moreover, the intimate heterojunction between Bi2MoO6 core and Bi2S3 shell can efficiently deteriorate the charge carrier recombination and Bi2S3 content can boost visible light harvesting, thereby contributing to the remarkable photocatalytic catalytic activity, which were proven by PL, EIS and transient photocurrent responses. Characterization of Mott–Schottky plots and DRS prove that the Bi2MoO6 & Bi2S3 heterojunctions established a type-II band alignment with intimate contact, accounting for the efficient transfer and separation of photogenerated carriers. This work provides a simple route for facial synthesis of heterojunction photocatalysts for Cr(VI) reduction in industrial applications.

Monthly runoff forecasting based on LSTM–ALO model

Abstract: Accurate runoff forecasting plays an important role in management and utilization of water resources. This paper investigates the accuracy of hybrid long short-term memory neural network and ant lion optimizer model (LSTM–ALO) in prediction of monthly runoff. As the parameters of long short-term memory neural network (LSTM) have influence on the prediction performance, the parameters of the LSTM are calibrated by using ant lion optimizer. Then the selection of suitable input variables of the LSTM–ALO is discussed for monthly runoff forecasting. Finally, we decompose root mean square error into three parts, which can help us better understanding the origin of differences between the observed and predicted runoff. To test the merits of the LSTM–ALO for monthly runoff forecasting, other models are employed to compare with the LSTM–ALO. The scatter-plots and box-plots are adopted for evaluating the performance of all models. In the case study, simulation results with the historical monthly runoff of the Astor River Basin show that the LSTM–ALO model has higher accuracy than that of other models. Therefore, the proposed LSTM–ALO provides an effective method for monthly runoff forecasting.

A Survey on Mobile Data Offloading Technologies

Abstract: Recently, due to the increasing popularity of enjoying various multimedia services on mobile devices (e.g., smartphones, ipads, and electronic tablets), the generated mobile data traffic has been explosively growing and has become a serve burden on mobile network operators. To address such a serious challenge in mobile networks, an effective approach is to manage data traffic by using complementary technologies (e.g., small cell network, WiFi network, and so on) to achieve mobile data offloading. In this paper, we discuss the recent advances in the techniques of mobile data offloading. Particularly, based on the initiator diversity of data offloading, we classify the existing mobile data offloading technologies into four categories, i.e., data offloading through small cell networks, data offloading through WiFi networks, data offloading through opportunistic mobile networks, and data offloading through heterogeneous networks. Besides, we show a detailed taxonomy of the related mobile data offloading technologies by discussing the pros and cons for various offloading technologies for different problems in mobile networks. Finally, we outline some opening research issues and challenges, which can provide guidelines for future research work.

V2V Data Offloading for Cellular Network Based on the Software Defined Network (SDN) Inside Mobile Edge Computing (MEC) Architecture

Abstract: Data offloading plays an important role for the mobile data explosion problem that occurs in cellular networks. This paper proposed an idea and control scheme for offloading vehicular communication traffic in the cellular network to vehicle to vehicle (V2V) paths that can exist in vehicular ad hoc networks (VANETs). A software-defined network (SDN) inside the mobile edge computing (MEC) architecture, which is abbreviated as the SDNi-MEC server, is devised in this paper to tackle the complicated issues of VANET V2V offloading. Using the proposed SDNi-MEC architecture, each vehicle reports its contextual information to the context database of the SDNi-MEC server, and the SDN controller of the SDNi-MEC server calculates whether there is a V2V path between the two vehicles that are currently communicating with each other through the cellular network. This proposed method: 1) uses each vehicle’s context; 2) adopts a centralized management strategy for calculation and notification; and 3) tries to establish a VANET routing path for paired vehicles that are currently communicating with each other using a cellular network. The performance analysis for the proposed offloading control scheme based on the SDNi-MEC server architecture shows that it has better throughput in both the cellular networking link and the V2V paths when the vehicle’s density is in the middle.

Tunable MoS2/SnO2 P–N Heterojunctions for an Efficient Trimethylamine Gas Sensor and 4-Nitrophenol Reduction Catalyst

Abstract: Synthetic design and construction of P–N heterojunctions are attracting increasing attention due to their potential applications such as in catalysis, gas sensors, and energy storage and conversion...

Engineering design toward exploring the functional group substitution in 1D channels of Zn–organic frameworks upon nitro explosives and antibiotics detection

Abstract: Three isostructural metal–organic frameworks denoted as Zn(L)(aip)·(H2O) (1), Zn(L)(ip)·(DMF)(H2O)1.5 (2), and Zn(L)(HBTC)·(H2O)2 (3) with functional groups –NH2, –H and –COOH, respectively, decorated on the 1D channels have been rationally designed with the purpose of exploring the influence of electron transfer from organic ligands in the 1D channels on the sensing of nitro explosives and antibiotics. These three compounds exhibit strong fluorescence in water, and they can be applied to detect the presence of explosives or antibiotics by means of fluorescence quenching in aqueous solution, whereas in terms of special explosives or antibiotics at the same concentration, 3 demonstrates a more superior quenching efficiency than 1 and 2. More importantly, it has been found that the difference in the sensing performances of these compounds is closely related to the interaction between the functional groups and guest molecules via electron and energy transfer from MOFs to explosives and antibiotics.

Natural Biomass-Derived Hierarchical Porous Carbon Synthesized by an in Situ Hard Template Coupled with NaOH Activation for Ultrahigh Rate Supercapacitors

Abstract: An in situ hard template strategy coupled with NaOH activation is proposed to prepare hierarchical porous carbons with high surface area from biomass for high-performance supercapacitors. The preparation of the carbon includes the sol–gel process of lotus seed shell and sodium phytate, followed by carbonization and NaOH activation. The soluble sodium phytate is pyrolyzed to nano-Na5P3O10 during carbonization and then reacts with NaOH to convert to nano-Na2CO3 and nano-Na3PO4 particles, which are encapsulated in the carbon matrix as the in situ hard templates and leave large mesopores/macropores after being removed in the subsequent washing treatment. Combined with the micropores created by NaOH activation, the as-prepared carbons possess developed hierarchical pores with a large surface area of 3188 m2 g–1 and a pore volume of 3.2 cm3 g–1. Furthermore, the carbons are rich in the heteroatoms of O, N, and P originated from the biomass precursors and sodium phytate. As a result, the biomass-derived hierarch...

A Hybrid Bat Algorithm for Economic Dispatch With Random Wind Power

Abstract: We present a hybrid metaheuristic optimization algorithm for solving economic dispatch problems in power systems. The proposed algorithm, based on bat algorithm, combines chaotic map and random black hole model together. Chaotic map is used to prevent premature convergence, and the random black hole model is helpful not only in avoiding premature convergence, but also in increasing the global search ability, enlarging exploitation area and accelerating convergence speed. The pseudocode and related parameters of the proposed algorithm are also given in this paper. Different from other related works, the costs of conventional thermal generators and random wind power are both included in the cost function because of the increasing penetration of wind power. The proposed algorithm has no requirement on the convexity or continuous differentiability of the cost function, although the effect on fuel cost, caused by the underestimation and overestimation of wind power, is included. This makes it feasible to take more practical nonlinear constraints into account, such as prohibited operating zones and ramp rate limits. Three test cases are given to illustrate the effectiveness of the proposed method.

Doped, conductive SiO 2 nanoparticles for large microwave absorption.

Abstract: Although many materials have been studied for the purpose of microwave absorption, SiO2 has never been reported as a good candidate. In this study, we present for the first time that doped, microwave conductive SiO2 nanoparticles can possess an excellent microwave absorbing performance. A large microwave reflection loss (RL) of −55.09 dB can be obtained. The large microwave absorption originates mainly from electrical relaxation rather than the magnetic relaxation of the incoming microwave field. The electrical relaxation is attributed to a large electrical conductivity that is enabled by the incorporation of heterogeneous (N, C and Cl) atoms. The removal of the magnetic susceptibility only results in a negligible influence of the microwave absorption. In contrast, the removal of the heterogeneous atoms leads to a large decrease in the electrical conductivity and microwave absorption performance. Meanwhile, the microwave absorption characteristics can be largely adjusted with a change of the thickness, which provides large flexibility for various microwave absorption applications. Doped nanoparticles of silica (SiO2) have been found to act as a very strong absorber of microwave radiation. A US-Chinese collaboration of scientists discovered that, unlike pure SiO2 nanoparticles, those doped with atoms of N, C and Cl induce a reflection loss at large as −55 dB at a frequency of around 7 GHz. The doped nanoparticles, which measured 4–8 nm in diameter, were fabricated by slowly adding the precursor tetraethyl orthosilicate (TEOS) to the solvent N,N’-dimethylformamide (DMF) and then adding hydrazine monohydrochlorid. The resulting solution was then heated, washed and dried. The resulting nanoparticles were then dispersed in paraffin wax rings and the permittivity and permeability measured in the 1.0–18.0 GHz range using a network analyzer. The team attributes the strong microwave absorption to the doped nanoparticles’ good electrical conductivity.

Exploring Sodium-Ion Storage Mechanism in Hard Carbons with Different Microstructure Prepared by Ball-Milling Method.

Abstract: Hard carbon is considered as one of the most promising anodes in sodium-ion batteries due to its high capacity, low cost, and abundant resources However, the available capacity and low initial Coulombic efficiency (ICE) limits the practical application of hard carbon anode This issue results from the unclear understanding of the Na+ storage mechanism in hard carbon In this work, a series of hard carbons with different microstructures are synthesized through an "up to down" approach by using a simple ball-milling method to illustrate the sodium-ion storage mechanism The results demonstrate that ball-milled hard carbon with more defects and smaller microcrystalline size shows less low-potential-plateau capacity and lower ICE, which provides further evidence to the "adsorption-insertion" mechanism This work might give a new perspective to design hard carbon material with a proper structure for efficient sodium-ion storage to develop high-performance sodium-ion batteries

A ratiometric fluorescent probe for formaldehyde in aqueous solution, serum and air using aza-cope reaction

Abstract: Developing simple and selective methods for formaldehyde (FA) detection are of great interest, because FA is not only an environmental pollutant, but also an endogenous bioactive molecule. Herein, a new ratiometric fluorescent probe (HBT-FA) based on aza-Cope reaction was designed and synthesized, which showed high selectivity and ratiometric fluorescence response to FA. Furthermore, the probe could detect FA in various medium, such as aqueous solution, serum and air.

Ultrafine Pt Nanoparticles and Amorphous Nickel Supported on 3D Mesoporous Carbon Derived from Cu-Metal-Organic Framework for Efficient Methanol Oxidation and Nitrophenol Reduction.

Abstract: The development of novel strategy to produce new porous carbon materials is extremely important because these materials have wide applications in energy storage/conversion, mixture separation, and catalysis. Herein, for the first time, a novel 3D carbon substrate with hierarchical pores derived from commercially available Cu-MOF (metal-organic framework) (HKUST-1) through carbonization and chemical etching has been employed as the catalysts' support. Highly dispersed Pt nanoparticles and amorphous nickel were evenly dispersed on the surface or embedded within carbon matrix. The corresponding optimal composite catalyst exhibits a high mass-specific peak current of 1195 mA mg-1 Pt and excellent poison resistance capacity ( IF/ IB = 1.58) for methanol oxidation compared to commercial Pt/C (20%). Moreover, both composite catalysts manifest outstanding properties in the reduction of nitrophenol and demonstrate diverse selectivities for 2/3/4-nitrophenol, which can be attributed to different integrated forms between active species and carbon matrix. This attractive route offers broad prospects for the usage of a large number of available MOFs in fabricating functional carbon materials as well as highly active carbon-based electrocatalysts and heterogeneous organic catalysts.

Data Offloading Techniques Through Vehicular Ad Hoc Networks: A Survey

Abstract: Recently, for satisfying users’ various mobile Internet service requests for data exchange anytime and anywhere even in their moving vehicles, the generated mobile data traffic has been rapidly increasing and has become a serious burden on current cellular networks. To partially address such a serve challenge, vehicular ad hoc networks (VANETs) have emerged as an effective approach for enhancing vehicular services and applications by equipping vehicles with wireless and processing capabilities. In this paper, we survey the recent advances in the data offloading techniques through VANETs. Particularly, based on the communication patterns among vehicles and infrastructures, we classify these techniques into three categories, i.e., data offloading through vehicle-to-vehicle communications, vehicle-to-infrastructure communications, and vehicle-to-everything communications. Besides, we present a detailed taxonomy of the related techniques by discussing the pros and cons for various offloading techniques for different problems in VANETs. Finally, some opening research issues and challenges are outlined to provide guidelines for future research work.