Superb Efficiency Research Articles

UiO-66 derived N-doped carbon nanoparticles coated by PANI for simultaneous adsorption and reduction of hexavalent chromium from waste water

Recently, metal organic frameworks (MOFs) have been regarded as a type of uniformly and stably precursor and efficient self-sacrificial template to prepare hierarchical porous carbon related nano-structured functional materials. Herein, we report the use of the zirconium MOFs (UiO-66) as a precursor to prepare N-doped carbon nanoparticles (NC) with high specific surface area (1609.1 m2/g) by direct carbonization and etching processes. Then, polyaniline (PANI) was growth on the NC by in-situ polymerization, showing a superb efficiency and stability for hexavalent chromium (Cr(VI)) removal. Due to the synergistic effect of adsorption and reduction of the obtained PANI@NC nanocomposites, the maximum adsorption capacity was 198.04 mg/g. The effects of different adsorbents, pH, adsorbent dosage, co-existing ions, concentration of Cr(VI) were studied on the Cr(VI) adsorption. The kinetics of adsorption of Cr(VI) followed the Pseudo-second-order model and the adsorption isotherm data fitted well to the Langmuir isothermal model. Importantly, excellent stability of PANI@NC nanocomposites was demonstrated after five cycles. The results of this research indicate that PANI@NC nanocomposites were the promising adsorbent for removal of Cr(VI) from waste water.

An efficient solver for fully coupled solution of interaction between incompressible fluid flow and nanocomposite truncated conical shells

In this research, the dynamic instabilities of nanocomposite truncated conical shells containing a quiescent or a flowing inviscid fluid are scrutinized. Nonlinear dynamic equations are established according to the Novozhilov nonlinear shell theory along with Green’s strains and Hamilton principle. The velocity potential and Bernoulli’s equations are adopted to calculate fluid pressure acting on the conical shell. The nonlinear governing equations are discretized using trigonometric expansion through the circumferential direction and generalized differential quadrature method (GDQM) through the meridional direction. A detailed parametric study is directed to provide an insight into the influence of volume fraction of carbon nanotubes (CNTs), CNT dispersion, geometrical parameters, and boundary conditions on the divergence and flutter instabilities of nanocomposite truncated conical shells. This study shows the superb efficiency of the outlined solution procedure in reducing computational costs and virtual storage. The simulation indicates that the beginning of divergence and flutter instabilities can be significantly postponed by selecting an appropriate dispersion of CNTs through the thickness of the conical shell. Furthermore, the onset of flutter and divergence instabilities are found to be very sensitive to the semi-vertex angle and thickness-to-radius ratio. The results of this research shed light into using ultra-high-strength and low-weight nanocomposite for pressure vessels applications.

Rational design of three-phase interfaces for electrocatalysis

Gas-involving electrochemical reactions, like oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER), are critical processes for energy-saving, environment-friendly energy conversion and storage technologies which gain increasing attention. The development of according electrocatalysts is key to boost their electrocatalytic performances. Dramatic efforts have been put into the development of advanced electrocatalysts to overcome sluggish kinetics. On the other hand, the electrode interfaces-architecture construction plays an equally important role for practical applications because these imperative electrode reactions generally proceed at triple-phase interfaces of gas, liquid electrolyte, and solid electrocatalyst. A desirable architecture should facilitate the complicate reactions occur at the triple-phase interfaces, which including mass diffusion, surface reaction and electron transfer. In this review, we will summarize some design principles and synthetic strategies for optimizing triple-phase interfaces of gas-involving electrocatalysis systematically, based on the electrode reaction process at the three-phase interfaces. It can be divided into three main optimization directions: exposure of active sites, promotion of mass diffusion and acceleration of electron transfer. Furthermore, we especially highlight several remarkable works with comprehensive optimization about specific energy conversion devices, including metal-air batteries, fuel cells, and water-splitting devices are demonstrated with superb efficiency. In the last section, the perspectives and challenges in the future are proposed.

Parallel mining of contextual outlier using sparse subspace

In this paper, we present a parallel computing solution for an existing outlier mining method (LOMA)–a local outlier detection technique. As datasets increase radically in size, there is a pressing demand to develop highly scalable outlier detection algorithms that leverages modern distributed and parallel computing infrastructures. It is challenging to devise parallel outlier detection techniques, because sharing and accessing global data across multiple computing nodes inevitably impose I/O overheads. To address this concern, we design a parallel LOMA computing framework called PLOMA, which is composed of three modules, namely, parallel data reduction, local sparse-subspace construction, and sparse-subspace validation. The parallel data reduction module exhibits superb efficiency by the virtue of the sampling technology to compute k nearest neighbor. At the heart of PLOMA is a local sparse-subspace construction module, which extends the discrete particle swarm optimization method to search local sparse subspaces on multiple datanodes in parallel. The validation module allows PLOMA to maintain high mining accuracy by verifying the correctness of the local sparse subspaces obtained by the construction module. Furthermore, PLOMA produces contextual information serving as insightful explanations on detected outliers, thereby achieving high interpretability. We apply PLOMA algorithm to the astronomical spectral data for discovering peculiar celestial objects. Our comprehensive experimental study using a 24-nodes Hadoop cluster confirms that PLOMA achieves high performance in terms of extensibility, scalability, and interpretability.

Enhancing electron transport via graphene quantum dot/SnO2 composites for efficient and durable flexible perovskite photovoltaics

Low-temperature processed GQDs and SnO2 nanoparticles composites (G@SnO2) have been prepared through a facile synthetic path. Facilitated electron transfer and suppressed interfacial charge recombination enable flexible perovskite solar cells with superb efficiency and excellent durability.

Rapid ultrasound assisted hydrothermal synthesis of highly pure nanozeolite X from fly ash for efficient treatment of industrial effluent

Nanoporous green materials like nanozeolite has been in focus for their superb efficiency to treat industrial wastewater. The study reports ultrasound assisted hydrothermal method as a very fast method to convert industrial fly ash from different sources of eastern India to nanozeolite X for efficient removal of toxic dyes and metals from industrial effluent. The pure nanosized zeolite X was synthesized rapidly at 20 min of ultrasound treatment after alkali fusion. The efficiency of nanozeolite X was determined in terms of the adsorption capacity towards various divalent ions such as Zn2+, Cu2+, Cd2+, Pb2+, Ni2+, Ca2+, and Mg2+ as well as various dyes such as methylene blue, crystal violet, indigo carmine, and Congo red. In comparison to commercially available microporous Zeolite X (a maximum of 120.43 mg g−1 for Pb2+ and 134.62 mg g−1 by for methylene blue), all synthesized nanozeolite X shows high adsorption capacity for metals (a maximum of 196.24 mg g−1 for Pb2+) as well as dyes (193.45 mg g−1 for methylene blue). Highly pure nanozeolite X has shown immense potential for treatment of real time industrial wastewater.

Kinetic Resolution of β-Hydroxy Carbonyl Compounds via Enantioselective Dehydration Using a Cation-Binding Catalyst: Facile Access to Enantiopure Chiral Aldols.

A practical and highly enantioselective nonenzymatic kinetic resolution of racemic β-hydroxy carbonyl (aldol) compounds through enantioselective dehydration process was developed using a cation-binding Song's oligoethylene glycol (oligoEG) catalyst with potassium fluoride (KF) as base. A wide range of racemic aldols was resolved with extremely high selectivity factors ( s = up to 2393) under mild reaction conditions. This protocol is easily scalable. It provides an alternative approach for the syntheses of diverse biologically and pharmaceutically relevant chiral aldols in enantiomerically pure form. For example, racemic gingerols could participate in this kinetic resolution with superb efficiency ( s > 240), affording both enantiomerically pure gingerols and corresponding shogaols simultaneously in a single step. The dramatic effectiveness of such kinetic resolution process can be ascribed to systematic cooperative hydrogen-bonding catalysis in a densely confined supramolecular chiral cage in situ generated from the chiral catalyst, substrate, and KF.

Core-shell iron oxide-layered double hydroxide: High electrochemical sensing performance of H2O2 biomarker in live cancer cells with plasma therapeutics

In this work, we develop a new type of multifunctional core-shell nanomaterial by controllable integration of CuAl layered double hydroxides (LDHs) over the surface of iron oxides (Fe3O4) nanospheres (NSs) to fabricate (Fe3O4@CuAl NSs) hybrid material with interior tunability of LDH phase and explore its practical application in ultrasensitive detection of emerging biomarker, i.e., H2O2 as cancer diagnostic probe. In addition, atmospheric pressure plasmas (APPs) have also been used as potential therapeutic approach for cancer treatment. Due to the synergistic combination of p-type semiconductive channels of LDHs with multi-functional properties, unique morphology and abundant surface active sites, the Fe3O4@CuAl NSs modified electrode exhibited attractive electrocatalytic activity towards H2O2 reduction. Under the optimized conditions, the proposed biosensor demonstrated striking electrochemical sensing performances to H2O2 including linear range as broad as 8 orders of magnitude, low real detection limit of 1nM (S/N = 3), high sensitivity, good reproducibility and long-term stability. Arising from the superb efficiency, the electrochemical biosensor has been used for in vitro determination of H2O2 concentrations in human urine and serum samples prior to and following the intake of coffee, and real-time monitoring of H2O2 efflux from different cancer cell lines in normal state and after plasma treatment. We believe that this novel nano-platform of structurally integrated core-shell nanohybrid materials combined with APPs will enhance diagnostic as well as therapeutic window for cancer diseases.

Fast and high efficiency adsorption of Pb(II) ions by Cu/ZnO composite

Cu/ZnO composite with surface area of 35.10m2/g and high adsorption capacity of lead ions was successfully prepared by a simple sol-gel method. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and BET surface area studies outcome revealed the substitution of Cu into ZnO lattice with additional Cu-O phase. The average diameter of the composite was about16nm. The synthesized nanocomposites has a short adsorption equilibrium time of 35.0min as well as a superb efficiency for Pb(II) ions removal (1111.0mg.g−1).

Computationally efficient model for flow-induced instability of CNT reinforced functionally graded truncated conical curved panels subjected to axial compression

As a first endeavor, the aeroelastic responses of functionally graded carbon nanotube reinforced composite (FG-CNTRC) truncated conical curved panels subjected to aerodynamic load and axial compression are investigated. The nonlinear dynamic equations of FG-CNTRC conical curved panels are derived according to Green’s strains and the Novozhilov nonlinear shell theory. The aerodynamic load is estimated in accordance with the quasi-steady Krumhaar’s modified supersonic piston theory by taking into account the effect of the panel curvature. Matrix transform method along with the harmonic differential quadrature method (HDQM) are employed to solve the nonlinear equations of motion of the FG-CNTRC truncated conical curved panel. The advantage of the matrix transform method is that we only need to discretize the meridional direction. Effects of semi-vertex angle of the cone, subtended angle of the panel, boundary conditions, geometrical parameters, volume fraction and distribution of CNT, and Mach number on the aeroelastic characteristics of the FG-CNTRC conical curved panel are put into evidence via a set of parametric studies and pertinent conclusions are outlined. The results prove that the panels with different FG distributions have different critical dynamic pressure. It is found that the semi-vertex and subtended angles play a pivotal role in changing the critical circumferential mode number of the flutter instability. Besides, the research shows that the superb efficiency of proposed method with few grid points, which requires less CPU time, are attributed to the matrix transform method and the higher-order harmonic approximation function in the HDQM.

ChemInform Abstract: Material and Device Stability in Perovskite Solar Cells

AbstractReview: [34 refs.

Material and Device Stability in Perovskite Solar Cells

Organic-inorganic halide perovskite solar cells have attracted great attention because of their superb efficiency reaching 22 % and low-cost, facile fabrication processing. Nevertheless, stability issues in perovskite solar cells seem to block further advancements toward commercialization. Thus, device stability is one of the important topics in perovskite solar cell research. In the beginning, the poor moisture resistivity of the perovskite layer was considered as a main problem that hindered further development of perovskite solar cells, which encouraged engineering of the perovskite or protection of the perovskite by a buffer layer. Soon after, other parameters affecting long-term stability were sequentially found and various attempts have been made to enhance intrinsic and extrinsic stability. Here we review the recent progresses addressing stability issues in perovskite solar cells. In this report, we investigated factors affecting stability from material and device points of view. To gain a better understanding of the stability of the bulk perovskite material, decomposition mechanisms were investigated in relation to moisture, photons, and heat. Stability of full device should also be carefully examined because its stability is dependent not only on bulk perovskite but also on the interfaces and selective contacts. In addition, ion migration and current-voltage hysteresis were found to be closely related to stability.

Multilayer Extreme Learning Machine With Subnetwork Nodes for Representation Learning.

The extreme learning machine (ELM), which was originally proposed for "generalized" single-hidden layer feedforward neural networks, provides efficient unified learning solutions for the applications of clustering, regression, and classification. It presents competitive accuracy with superb efficiency in many applications. However, ELM with subnetwork nodes architecture has not attracted much research attentions. Recently, many methods have been proposed for supervised/unsupervised dimension reduction or representation learning, but these methods normally only work for one type of problem. This paper studies the general architecture of multilayer ELM (ML-ELM) with subnetwork nodes, showing that: 1) the proposed method provides a representation learning platform with unsupervised/supervised and compressed/sparse representation learning and 2) experimental results on ten image datasets and 16 classification datasets show that, compared to other conventional feature learning methods, the proposed ML-ELM with subnetwork nodes performs competitively or much better than other feature learning methods.

Biogenic synthesis of Ag, Au and bimetallic Au/Ag alloy nanoparticles using aqueous extract of mahogany ( Swietenia mahogani JACQ.) leaves

In this paper, we have demonstrated for the first time, the superb efficiency of aqueous extract of dried leaves of mahogany ( Swietenia mahogani JACQ.) in the rapid synthesis of stable monometallic Au and Ag nanoparticles and also Au/Ag bimetallic alloy nanoparticles having spectacular morphologies. Our method was clean, nontoxic and environment friendly. When exposed to aqueous mahogany leaf extract, competitive reduction of Au III and Ag I ions present simultaneously in same solution leads to the production of bimetallic Au/Ag alloy nanoparticles. UV–visible spectroscopy was used to monitor the kinetics of nanoparticles formation. UV–visible spectroscopic data and TEM images revealed the formation of bimetallic Au/Ag alloy nanoparticles. Mahogany leaf extract contains various polyhydroxy limonoids which are responsible for the reduction of Au III and Ag I ions leading to the formation and stabilization of Au and Ag nanopaticles.

Diamond LED Substrate and Novel Quantum Dots

Nitride LED (e.g., GaN) has become the mainstream of blue light source. The blue light can be converted to white light by exciting a phosphor (e.g., Nichia's YAG or Osram's TAG) with the complementary yellow emission. However, GaN is typically deposited on sapphire (Al2O3) substrates formed by crystal pulling or hexagonal (e.g., 4 H or 6 H) SiC wafers condensed from SiC vapor. In either case, the nitride lattice is ridden (e.g., 10(9)/cm2) with dislocations. The high dislocation density with sapphire is due to the large (>13%) lattice mismatch; and with hexagonal SiC, because of intrinsic defects. Cubic (beta) SiC may be deposited epitaxially using a CVD reactor onto silicon wafer by diffusing the interface and by chemical gradation. A reactive echant (e.g., hydrogen or fluorine) can be introduced periodically to gasify mis-aligned atoms. In this case, large single crystal wafers would be available for the manufacture of high bright LED with superb electro-optical efficiency. The SiC wafer may be coated with diamond film that can eliminate heat in real time. As a result of lower temperature, the nitride LED can be brighter and it will last longer. The blue light of GaN LED formed on SiC on Diamond (SiCON) LED may also be scattered by using novel quantum dots (e.g., 33 atom pairs of CdSe) to form a broad yellow light that blend in with the original blue light to form sunlight-like white light. This would be the ideal source for general illumination (e.g., for indoor) or backlighting (e.g., for LCD).

The application of special matrix product to differential quadrature solution of geometrically nonlinear bending of orthotropic rectangular plates

The Hadamard and SJT product of matrices are two types of special matrix product. The latter was first defined by Chen. In this study, they are applied to the differential quadrature (DQ) solution of geometrically nonlinear bending of isotropic and orthotropic rectangular plates. By using the Hadamard product, the nonlinear formulations are greatly simplified, while the SJT product approach minimizes the effort to evaluate the Jacobian derivative matrix in the Newton–Raphson method for solving the resultant nonlinear formulations. In addition, the coupled nonlinear formulations for the present problems can easily be decoupled by means of the Hadamard and SJT product. Therefore, the size of the simultaneous nonlinear algebraic equations is reduced by two-thirds and the computing effort and storage requirements are greatly alleviated. Two recent approaches applying the multiple boundary conditions are employed in the present DQ nonlinear computations. The solution accuracies are significantly improved in comparison to the previously given by Bert et al. The numerical results and detailed solution procedures are provided to demonstrate the superb efficiency, accuracy and simplicity of the new approaches in applying DQ method for nonlinear computations.

Absolute spectrophotometry of Titan, Uranus, and Neptune: 30,500–10,500 Å

Absolute measurements of the geometric albedo spectra of Titan, Uranus, and Neptune from 3500 to 10,500 Å are reported. The measurements have spectral resolution of about 7 Å and high signal-to-noise ratio owing to the superb efficiency of the spectrograph and Reticon detector used to acquire them. Agreement is excellent with albedo measurements of Uranus G. W. Lockwood, B. L. Lutz, D. T. Thompson, and A. Warnock (1983, Astrophys. J., 266, 402–414). The high precision and spectral resolution of the data make possible quantitative measurements of the effects of Raman scattering by H 2 in the atmospheres of Uranus and Neptune.