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A convenient and efficient method is developed for the synthesis of 1,2,3,4,6‐pentasubstituted piperidines via a three‐component, one‐pot domino reaction of β‐ketoesters, aromatic aldehydes, and aromatic amines in the presence of a catalytic amount of saccharin in methanol at 40°C. The desired piperidines could be easily collected through simple filtration with excellent diastereoselectivities. [ABSTRACT FROM AUTHOR]

Bow shape has been recognized as an important factor influencing the seakeeping performance and added resistance of ships. This paper presents a numerical comparative study on added resistance and seakeeping of model ships with 'X-bow' and a wave-piercing monohull in regular head waves using a computational fluid dynamics (CFD) software. Different wave heights, wavelengths and forward speeds are considered in the systematic investigation in order to characterize the added resistance and wave-induced motions, and to explore the local wave patterns. The results show a considerably different hydrodynamic characteristic by different bow shapes. [ABSTRACT FROM AUTHOR]

A simple, efficient and green approach to the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones has been developed via one-pot three-component reaction of aromatic aldehyde, malononitrile and phthalhydrazide catalyzed by zinc–proline complex (Zn[L-proline]2) using H2O: PEG400 = 6: 4 as solvent. Atom economy, good to excellent yield, operational simplicity and easy workup are important features of this method. [ABSTRACT FROM AUTHOR]

An efficient method for the synthesis of highly functionalized piperidines via one-pot domino reaction of β-ketoesters, aromatic aldehydes, and aromatic amines was reported. This multicomponent coupling was catalyzed by TMSI in methanol at room temperature, giving desired substituted pyridines in moderate to good yields. [ABSTRACT FROM AUTHOR]

In the Lagrangian meshless (particle) methods, such as the smoothed particle hydrodynamics (SPH), moving particle semi-implicit (MPS) method and meshless local Petrov-Galerkin method based on Rankine source solution (MLPG_R), the Laplacian discretisation is often required in order to solve the governing equations and/or estimate physical quantities (such as the viscous stresses). In some meshless applications, the Laplacians are also needed as stabilisation operators to enhance the pressure calculation. The particles in the Lagrangian methods move following the material velocity, yielding a disordered (random) particle distribution even though they may be distributed uniformly in the initial state. Different schemes have been developed for a direct estimation of second derivatives using finite difference, kernel integrations and weighted/moving least square method. Some of the schemes suffer from a poor convergent rate. Some have a better convergent rate but require inversions of high order matrices, yielding high computational costs. This paper presents a quadric semi-analytical finite-difference interpolation (QSFDI) scheme, which can achieve the same degree of the convergent rate as the best schemes available to date but requires the inversion of significant lower-order matrices, i.e. 3 × 3 for 3D cases, compared with 6 × 6 or 10 × 10 in the schemes with the best convergent rate. Systematic patch tests have been carried out for either estimating the Laplacian of given functions or solving Poisson's equations. The convergence, accuracy and robustness of the present schemes are compared with the existing schemes. It will show that the present scheme requires considerably less computational time to achieve the same accuracy as the best schemes available in literatures, particularly for estimating the Laplacian of given functions. [ABSTRACT FROM AUTHOR]

The organ-on-a-chip model mimics the structural and functional features of human tissues or organs and has great importance in translational research. For vessel-on-a-chip model, conventional fabrication techniques are unable to efficiently imitate the intimal-medial unit of the vessel wall. Bioprinting technology, which can precisely control the organization of cells, biomolecules, and the extracellular matrix, has the potential to fabricate three-dimensional (3D) tissue constructs with spatial heterogeneity. In this study, we applied the gelatin-methacryloyl-based bioprinting technology to print 3D construct containing endothelial cells (ECs) and smooth muscle cells (SMCs) on a microfluidic chip. Compared with traditional culture system, EC-SMC coculturing chip model upregulated αSMA and SM22 protein expression of the SMC to a greater degree and maintains the contractile phenotype of the SMC, which mimics the natural vascular microenvironment. This strategy enabled us to establish an in vitro vascular model for studies of the physiologic and pathologic process in vascular wall. [ABSTRACT FROM AUTHOR]

Vibrio cholerae, the most hazardous Vibrio species, is threatening aquacultured animals and even human beings. In recent years, a few genetic markers that target V. cholerae have been reported, but their application was limited by techniques or themselves. The outer membrane lipoprotein gene lolB has been identified as a specific marker by using PCR and quantitative PCR methods. In this study, we developed a real-time recombinase polymerase amplification (RPA) assay targeting lolB gene in an attempt to provide a sensitive, rapid, and reliable detection method of V. cholerae. The sensitivity of RPA assay was determined by amplifying the standard plasmid dilutions. The detection limit down to five copies was achieved within 10 min, which was lower than that of qPCR (ten copies after 25 cycles within 1.5 h). The reproducibility of RPA assay was verified by eight independent experiments, presenting a high R value of the standard regression line (0.97). In addition, the specificity was confirmed with DNA extracted from other bacteria, shrimps, clams, and fishes using both methods. Finally, V. cholerae in shrimp samples were quantified using real-time RPA and qPCR with consistent outcomes, while no amplification was obtained from clam and fish samples using both methods. The applicability in the food industry was confirmed by quantitative detection of natural seafood. [ABSTRACT FROM AUTHOR]

The viscosity plays an important role, and a multiphase solver is necessary to numerically simulate the oil spilling from a damaged double hull tank (DHT). However, it is uncertain whether turbulence modelling is necessary, which turbulence model is suitable; and what the role of compressibility of the fluids is. This paper presents experimental and numerical investigations to address these issues for various cases representing different scenarios of the oil spilling, including grounding and collision. In the numerical investigations, various approaches to model the turbulence, including the large eddy simulation (LES), direct numerical simulation and the Reynolds average Navier-Stokes equation (RANS) with different turbulence models, are employed. Based on the investigations, it is suggested that the effective Reynolds numbers corresponding to both oil outflow and water inflow shall be considered when classifying the significance of the turbulence and selecting the appropriate turbulence models. This is confirmed by new lab tests considering the axial offset between the internal and the external holes on two hulls of the DHT. The investigations conclude for numerically simulating oil spilling from a damaged DHT that when the effective Re is smaller the RANS approaches should not be used and LES modelling should be employed; while when the effective Reynolds numbers is large, the RANS models may be used as they can give similar results to LES in terms of the height of the mixture in the ballast tank and discharge but costing much less CPU time. The investigation on the role of the compressibility of the fluid reveals that the compressibility of the fluid may be considerable in a small temporal-spatial scale but plays an insignificant role on macroscopic process of the oil spilling. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Although there are numerous claims of remote group participation leading to the synthesis of the expected glycosides with improved anomeric geometry outcome in glycosylation, there is still a lack of enough strong evidence and this has led to a long-term debate, particularly for equatorial 4-O group participation. In this work, we were able to synthesize and isolate a stable seven-membered trichlorooxazepine ring bridging intermediate with a high yield by employing a 2-azido-2-deoxy-glucopyranosyl donor, which provides strong evidence to support the putative participation of the equatorial 4-O group in glycosylation. [ABSTRACT FROM AUTHOR]

Several hybrid sensing materials, which are prepared by the covalent grafting of organic fluorescent molecules onto inorganic supports, have emerged as a novel and promising class of hybrid sensing probes and have attracted tremendous interest. In comparison to the organic fluorescent sensors, the hybrid sensing probes incorporate the beneficial chemical/physical properties of the organic molecules and inorganic materials, which accelerate the development of hybrid materials for ion recognition and removal. Hence, the novel hybrid sensing materials can selectively monitor and efficiently remove specific analytes, which can provide a novel opportunity to synthesize multifunctional hybrid materials. Considerable efforts have been devoted to developing effective and innovative approaches for the design and synthesis of hybrid sensing materials that can display highly desirable performance for ion detection and removal. This tutorial review firstly presents a brief description of the hybrid materials and mesoporous silica materials and then classifies the hybrid sensing materials into several categories, including mesoporous silica based hybrid sensors, magnetic core–shell particle based hybrid sensors, magnetic nanoparticle based hybrid sensors, polymer based hybrid sensors, surface-grafted composite based hybrid sensors, and host–guest interaction based hybrid sensors, followed by a detailed summary of the design and synthesis of hybrid sensing materials and their applications in environmental and biological fields. Hopefully, this review will provide perspectives and guidelines for the development and further research of hybrid sensing materials. [ABSTRACT FROM AUTHOR]

In this study, magnetic elongated hollow mesoporous silica nanocapsules (MSNCs) with center-radial pore channels were successfully fabricated for the first time by using the surfactant-template synthesis approach. And, these novel nanomaterials were characterized by TEM, FTIR, XRD, XPS, VSM and N2 adsorption–desorption. These well-designed mesoporous silica nanocapsules have a very high specific surface area (860 m2 g−1), high pore volume (1.60 cm3 g−1) and highly opened biggish pore size (8 nm). To evaluate their supporting capability in catalytic reactions, the MSNCs were then functionalized with amino groups to robustly anchor silver nanoparticles (Ag NPs) to catalyze the reduction reaction of 4-nitrophenol and 2-nitroaniline. Significantly, Ag NPs were successfully supported in the abundant pore channels of the nanocapsules without any aggregation. The well synthesized multicomponent nanocatalyst exhibited excellent catalytic activity for the reduction of 4-NP and 2-NA in water at room temperature due to the abundant and high-efficiency accessible active sites. Interestingly, the novel catalysts have γ-Fe2O3 in the inner chamber so that they could be effortlessly recovered by magnetic separation from the reaction mixture and reused 10 times without any significant reduction in their catalytic activity. Therefore, the unique nanostructure based on the novel capsule-like mesoporous silica nanomaterial provided a useful platform for the fabrication of catalysts with superior activity, accessibility and easy recovery. And also, it is expected to be a significant template for the synthesis of other novel nanostructures. [ABSTRACT FROM AUTHOR]

Manganese oxides of various crystal structures (α-, β-, γ- and δ-MnO2, Mn2O3, Mn3O4 and amorphous) were synthesized by facile methods. The adsorption capacities for methyl orange of these materials were investigated and the resulting materials were characterized by different techniques, such as SEM, XRD and BET surface area measurements. The adsorption capacities were strongly dependent on the crystallographic structures and morphologies, and followed the order of A-MnO2 ＞ Mn2O3 ＞ Mn3O4 ＞ α-MnO2 nanowires ＞ β-MnO2 ＞ γ-MnO2 ＞ α-MnO2 nanotubes ＞δ-MnO2, while the adsorption properties could be greatly improved by increasing the surface area and pore properties of the adsorbents. A-MnO2 was found to be the most effective adsorbent among the other materials and the adsorption process was systematically investigated. The adsorption kinetics data closely followed the pseudo-second-order kinetic model and the results obtained from the intraparticle diffusion model indicated that the overall process was jointly influenced by external mass transfer and intra-particle diffusion. The maximum adsorption capacity determined from the Langmuir isotherm model was 1488.7 mg g−1. Moreover, thermodynamic analyses revealed that the adsorption of MO onto A-MnO2 was spontaneous and exothermic, and the physical adsorption mechanisms including electrostatic interactions played a dominant role in the adsorption process between MO and A-MnO2. These combined results indicated that A-MnO2 is an efficient adsorbent for the removal of MO from wastewater. [ABSTRACT FROM AUTHOR]

In the present work, a multifunctional core–shell magnetic fibrous silica sensing probe AQ-Fe3O4@SiO2@KCC-1 was prepared for the detection, adsorption and removal of Zn2+. The core was composed of superparamagnetic Fe3O4 nanodots, while the shell consisted of fibrous silica molecular sieve KCC-1 and was decorated by a quinoline derived probe. The multifunctional inorganic–organic hybrid material was characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption–desorption, thermogravimetric analysis, and vibrating sample magnetometry. Its sensing performance towards Zn2+ was then discussed in detail. The experimental results suggested that this functional material exhibited enhanced fluorescence in the presence of Zn2+ ions and a high selectivity for Zn2+ over the competing metal ions in aqueous solution. The binding ratio of the AQ-Fe3O4@SiO2@KCC-1–Zn2+ complexes was determined from the Job plot to be 1 : 1. The association constant was calculated to be 1.85 × 105 M−1, with a detection limit of 1.08 × 10−7 M. Furthermore, the adsorption process of Zn2+ on the magnetic fibrous silica composite AQ-Fe3O4@SiO2@KCC-1 was well described by the Langmuir isotherm equation and the equilibrium adsorption capacity is 157.2327 mg g−1. These results indicate that these multifunctional magnetic fibrous silica sensing materials may find potential and favorable applications for simple detection and efficient removal of Zn2+ in toxicological and environmental fields. [ABSTRACT FROM AUTHOR]

A multifunctional organic–inorganic hybrid sensing material (RB-KCC-1) was prepared by the immobilization of a rhodamine-based receptor (RB-Si) within the channels of fibrous silica spheres (KCC-1), and characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, N2 adsorption–desorption, and UV-vis absorption and fluorescence spectroscopy. This multifunctional sensor exhibits high surface area, large open pores and a flexible fibrous structure, and excellent optical sensing properties that allow for highly selective, sensitive and “naked eye” Hg2+ detection. The fluorescence enhancement responses of RB-KCC-1 are associated with the spirolactam ring opening of the rhodamine group, and a detection limit of 9.05 × 10−7 M is obtained. In additional, it is also an excellent adsorbent for the removal of Hg2+ from aqueous solution. The adsorption process of Hg2+ on RB-KCC-1 is well described by the Langmuir isotherm equation, and the equilibrium adsorption capacity is 115.47 mg g−1. These results indicate that these multifunctional composites may have good potential as favorable materials for the facile detection and effective removal of Hg2+ in biological, environmental, and industrial fields. [ABSTRACT FROM AUTHOR]

Two nanostructured proton-containing δ-MnO2 (H-δ-MnO2) materials were synthesized through proton exchange for K-containing δ-MnO2 (K-δ-MnO2) nanosheets and nanoparticles prepared by the hydrothermal homogeneous precipitation method and solid-state reaction. Energy-dispersive spectroscopy (EDS) measurements showed that the K+ cations were successfully leached away and replaced with H+ ions. The role of K+ cations in the adsorption process was first explored by replacing the K+ ions in the δ-MnO2 with H+ ions and the adsorption capacities for organic pollutants were investigated using methyl orange (MO) as a model. Experimental results indicated that the H-δ-MnO2 materials with a similar morphology and crystal structure showed excellent adsorption capacities of 375 and 427 mg g−1 for MO, because both of the nanostructured H-δ-MnO2 materials have much larger Brunauer–Emmett–Teller (BET) surface areas than that of K-δ-MnO2. The remarkable adsorption capacities of dye onto H-δ-MnO2 materials indicate that K+ cations in the layered δ-MnO2 structure have an unfavorable influence on the adsorption process. Moreover, physical adsorption mechanisms including electrostatic interaction play a dominant role in the adsorption mechanism between MO and adsorbents. This finding suggests that the proton-exchange process may be a useful method to improve the adsorption affinity of dye contaminants on δ-MnO2 and nanostructured proton-containing δ-MnO2 samples are good candidates for efficient MO removal from wastewater. [ABSTRACT FROM AUTHOR]

An efficient and convenient method for the selective cleavage of terminal acetonides is described. Treatment of terminal acetonides in the presence of a wide range of functional groups with silica-supported boron trifluoride as a catalyst furnished the corresponding diols in 82–95% yield under ultrasound irradiation conditions. The acid-labilep-methoxybenzyl group as a protecting group remained intact under the conditions employed to the present deprotection condition. [ABSTRACT FROM PUBLISHER]

An efficient, convenient protocol for the preparation of per-O-acetylated p-tolylthio glycosides is described. Treatment of various unprotected sugars, including 2-deoxy-2-amino sugars, sialic acid, lactose, and maltose, with acetic anhydride using SnCl4 as a catalyst, and subsequently with p-tolylthiol, furnished the corresponding thioglycosides in 71%–90% yield under solvent-free conditions. [ABSTRACT FROM AUTHOR]

Two floating structures in close proximity are very commonly seen in offshore engineering. They are often subjected to steep waves and, therefore, the transient effects on their hydrodynamic features are of great concern. This paper uses the quasi arbitrary Lagrangian-Eulerian finite element method (QALE-FEM), based on the fully nonlinear potential theory (FNPT), to numerically investigate the interaction between two 3-D floating structures, which undergo motions with 6 degrees of freedom (DOFs), and are subjected to waves with different incident angles. The transient behaviours of floating structures, the effect of the accompanied structures, and the nonlinearity on the motion of and the wave loads on the structures are the main focuses of the study. The investigation reveals an important transient effects causing considerably larger structure motion than that in steady state. The results also indicate that the accompanied structure in close proximity enhances the interaction between different motion modes and results in stronger nonlinearity causing 2-order component to be of similar significance to the fundamental one. [ABSTRACT FROM AUTHOR]

Accumulation of amyloid-β peptide (Aβ), the neurotoxic peptide implicated in the pathogenesis of Alzheimer's disease (AD), has been shown in brain mitochondria of AD patients and of AD transgenic mouse models. The presence of Aβ in mitochondria leads to free radical generation and neuronal stress. Recently, we identified the presequence protease, PreP, localized in the mitochondrial matrix in mammalian mitochondria as the novel mitochondrial Aβ-degrading enzyme. In the present study, we examined PreP activity in the mitochondrial matrix of the human brain's temporal lobe, an area of the brain highly susceptible to Aβ accumulation and reactive oxygen species (ROS) production. We found significantly lower hPreP activity in AD brains compared with non-AD age-matched controls. By contrast, in the cerebellum, a brain region typically spared from Aβ accumulation, there was no significant difference in hPreP activity when comparing AD samples to non-AD controls. We also found significantly reduced PreP activity in the mitochondrial matrix of AD transgenic mouse brains (Tg mAβPP and Tg mAβPP/ABAD) when compared to non-transgenic aged-matched mice. Furthermore, mitochondrial fractions isolated from AD brains and Tg mAβPP mice had higher levels of 4-hydroxynonenal, an oxidative product, as compared with those from non-AD and nonTg mice. Accordingly, activity of cytochrome c oxidase was significantly reduced in the AD mitochondria. These findings suggest that decreased PreP proteolytic activity, possibly due to enhanced ROS production, contributes to Aβ accumulation in mitochondria leading to the mitochondrial toxicity and neuronal death that is exacerbated in AD. Clearance of mitochondrial Aβ by PreP may thus be of importance in the pathology of AD. [ABSTRACT FROM AUTHOR]

Accumulation of amyloid-β peptide (Aβ), the neurotoxic peptide implicated in the pathogenesis of Alzheimer's disease (AD), has been shown in brain mitochondria of AD patients and of AD transgenic mouse models. The presence of Aβ in mitochondria leads to free radical generation and neuronal stress. Recently, we identified the presequence protease, PreP, localized in the mitochondrial matrix in mammalian mitochondria as the novel mitochondrial Aβ-degrading enzyme. In the present study, we examined PreP activity in the mitochondrial matrix of the human brain's temporal lobe, an area of the brain highly susceptible to Aβ accumulation and reactive oxygen species (ROS) production. We found significantly lower hPreP activity in AD brains compared with non-AD age-matched controls. By contrast, in the cerebellum, a brain region typically spared from Aβ accumulation, there was no significant difference in hPreP activity when comparing AD samples to non-AD controls. We also found significantly reduced PreP activity in the mitochondrial matrix of AD transgenic mouse brains (Tg mAβPP and Tg mAβPP/ABAD) when compared to non-transgenic aged-matched mice. Furthermore, mitochondrial fractions isolated from AD brains and Tg mAβPP mice had higher levels of 4-hydroxynonenal, an oxidative product, as compared with those from non-AD and nonTg mice. Accordingly, activity of cytochrome c oxidase was significantly reduced in the AD mitochondria. These findings suggest that decreased PreP proteolytic activity, possibly due to enhanced ROS production, contributes to Aβ accumulation in mitochondria leading to the mitochondrial toxicity and neuronal death that is exacerbated in AD. Clearance of mitochondrial Aβ by PreP may thus be of importance in the pathology of AD. [ABSTRACT FROM AUTHOR]

Inspired by the tubercles on humpback whale flippers, leading-edge tubercles have been incorporated into the design of wings and turbine blades in an attempt to improve their hydrodynamic performance. Although promising improvements, especially in terms of the stall performance, have been demonstrated in the limited research that exists to date, the effectiveness of the leading-edge tubercles seems to be influenced by the base blade. This paper focuses on the introduction of sinusoidal leading-edge tubercles to a base blade developed from the classic NACA0018 airfoil, and numerically investigates the effectiveness of leading-edge tubercles on the hydrodynamics associated with the blade in uniform current with different attack angles. Both the macroscopic parameters, such as the lift and drag forces, and the micro-scale flow characteristics, including the vortex and flow separation, are analyzed. The results indicate that the leading-edge tubercles brings a significant influence on the hydrodynamic forces acting on the blade when subjected to an attack angle greater than 15°. This study also reveals the important role of the turbulence and flow separation on hydrodynamic loading on the blade and the considerable influence of the tubercles on such micro-scale flow characteristics. Although the conditions applied in this work are relatively ideal (e.g., the blade is fixed in a uniform flow and the end effect is ignored), the satisfactory agreement between the numerical and corresponding experimental data implies that the results are acceptable. This work builds a good reference for our future work on the hydrodynamic performance of tidal turbines which adopt this kind of blade for operating in both uniform and shearing currents. [ABSTRACT FROM AUTHOR]