Single-step Strategy Research Articles

A linearisedhp-finite element framework for acousto-magneto-mechanical coupling in axisymmetric MRI scanners

We propose a new computational framework for the treatment of acousto-magneto-mechanical coupling that arises in low-frequency electro-magneto-mechanical systems such as magnetic resonance imaging scanners. Our transient Newton–Raphson strategy involves the solution of a monolithic system obtained from the linearisation of the coupled system of equations. Moreover, this framework, in the case of excitation from static and harmonic current sources, allows us to propose a simple linearised system and rigorously motivate a single-step strategy for understanding the response of systems under different frequencies of excitation. Motivated by the need to solve industrial problems rapidly, we restrict ourselves to solving problems consisting of axisymmetric geometries and current sources. Our treatment also discusses in detail the computational requirements for the solution of these coupled problems on unbounded domains and the accurate discretisation of the fields using hp–finite elements. We include a set of academic and industrially relevant examples to benchmark and illustrate our approach. Copyright © 2017 The Authors. International Journal for Numerical Methods in Engineering Published by John Wiley & Sons, Ltd.

Eccentric implants stand alone.

Controlling antibiotic drug clustering in replacement joint material provides a single-step strategy to clear infection while maintaining the mechanical strength needed for load bearing.

Purification of β-mannanase derived from Bacillus subtilis ATCC 11774 using ionic liquid as adjuvant in aqueous two-phase system.

The partitioning of β-mannanase derived from Bacillus subtilis ATCC 11774 in aqueous two-phase system (ATPS) was studied. The ATPS containing different molecular weight of polyethylene glycol (PEG) and types of salt were employed in this study. The PEG/salt composition for the partitioning of β-mannanase was optimized using response surface methodology. The study demonstrated that ATPS consists of 25% (w/w) of PEG 6000 and 12.52% (w/w) of potassium citrate is the optimum composition for the purification of β-mannanase with a purification fold (PF) of 2.28 and partition coefficient (K) of 1.14. The study on influences of pH and crude loading showed that ATPS with pH 8.0 and 1.5% (w/w) of crude loading gave highest PF of 3.1. To enhance the partitioning of β-mannanase, four ionic liquids namely 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4), 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF4), 1-butyl-3-methylimidazolium bromide ([Bmim]Br), 1-ethyl-3-methylimidazolium bromide ([Emim]Br) was added into the system as an adjuvant. The highest recovery yield (89.65%) was obtained with addition of 3% (w/w) of [Bmim]BF4. The SDS-PAGE analysis revealed that the β-mannanase was successfully recovered in the top phase of ATPS with the molecular size of 36.7kDa. Therefore, ATPS demonstrated a simple and efficient approach for recovery and purification of β-mannanase from fermentation broth in one single-step strategy.

Facile method to synthesize dopamine-capped mixed ferrite nanoparticles and their peroxidase-like activity

A facile single-step strategy to prepare stable and water-dispersible dopamine-functionalized ultra-small mixed ferrite nanoparticles MFe2O4-DOPA (where M is a bivalent metal atom i.e. Fe, Co Cu, Mn and Ni) at room temperature is described. The nanoparticles formed have narrow size distribution as indicated by their characterization using transmission electron microscopy (TEM) and dynamic light scattering. The surface chemistry of these nanoparticles was probed by FTIR spectroscopy indicating their successful capping with dopamine ligands, which was further confirmed using zetapotential measurements and thermogravimetric analysis. The comparative horseradish peroxidase (HRP)—like activity of these cationic mixed ferrites nanoparticles was studied at pH 4.6 using a negatively-charged 2, 2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) as a chromogenic substrate in the presence of hydrogen peroxide. A time-dependent relative peroxidase-like activity follows the following order CoFe2O4-DOPA > MnFe2O4-DOPA > CuFe2O4-DOPA > NiFe2O4-DOPA > Fe3O4-DOPA. This diversity in HRP-like activity may be attributed to the different redox properties of ferrite nanoparticles when doped with M (Fe, Co Cu, Mn and Ni).

A facile one-step strategy for in-situ fabrication of WO3-BiVO4 nanoarrays for solar-driven photoelectrochemical water splitting applications

This paper presents a facile single step strategy for fabrication of tungsten, bismuth and vanadium mixed metal oxide nanoarrays. WO3-BiVO4 heteronanostructure was obtained hydrothermally with reaction time of two hrs at low temperature 110°C. The morphology of as prepared WO3-BiVO4 heterostructure revealed uniform and prominent nanorods like architectures under FE-SEM. These heteronanostructures were of variable sizes i.e., width ⩽100nm and length 200–400nm respectively. The energy dispersive X-ray analysis (EDX) and elemental mapping of heteronanostructure further confirmed W, Bi, V and O entities in good elemental composition. The purity and crystalline nature of as synthesized WO3-BiVO4 were confirmed from X-ray crystallographic (XRD) analysis. UV–Visible spectroscopy and Raman analysis were also carried out to investigate optical properties of WO3-BiVO4. The band gap energy of WO3-BiVO4 calculated from UV–Visible absorption and diffused reflectance spectroscopy’s was observed to be 2.1eV respectively. The photoelectrochemical (PEC) studies of FTO coated WO3-BiVO4 showed a stable and repeatable photocurrent response under 1 SUN solar irradiation source. The linear sweep voltammetry (LSV) and Cyclic Voltammetry (CV) also corroborated substantial photocurrents at different oxidation and reduction potentials. Consequently, it is envisioned that this one-step strategy for in-situ fabrication of WO3-BiVO4 heteronanostructures have potential applications in solar-driven photoelectrochemical water splitting reactions.

Incorporating the single-step strategy into a random regression model to enhance genomic prediction of longitudinal traits.

In prediction of genomic values, the single-step method has been demonstrated to outperform multi-step methods. In statistical analyses of longitudinal traits, the random regression test-day model (RR-TDM) has clear advantages over other models. Our goal in this study was to evaluate the performance of a model that integrates both single-step and RR-TDM prediction methods, called the single-step random regression test-day model (SS RR-TDM), in comparison with the pedigree-based RR-TDM and genomic best linear unbiased prediction (GBLUP) model. We performed extensive simulations to exploit the potential advantages of SS RR-TDM over the other two models under various scenarios with different levels of heritability, number of quantitative trait loci, as well as selection scheme. SS RR-TDM was found to achieve the highest accuracy and unbiasedness under all scenarios, exhibiting robust prediction ability in longitudinal trait analyses. Moreover, SS RR-TDM showed better persistency of accuracy over generations than the GBLUP model. In addition, we also found that the SS RR-TDM had advantages over RR-TDM and GBLUP in terms of its being a real data set of humans contributed by the Genetic Analysis Workshop 18. The findings of our study demonstrated the feasibility and advantages of SS RR-TDM, thus enhancing the strategies for genomic prediction of longitudinal traits in the future.

Efficient synthesis, fluorescence and DFT studies of different substituted 2-chloroquinoline-4-amines and benzo[g][1,8]naphthyridine derivatives

Abstract An efficient and single step strategy for synthesizing new functionalized benzo[b][1,8]naphthyridine derivatives is presented. Benzo[g][1,8]naphthyridines have been synthesized by the condensation of substituted 2-chloroquinoline-3-carbaldehydes with various 2-chloroquinoline-4-amines, 1H-Indazole-6-amine in basic medium. The electro luminescence and photophysical properties of a series of benzo[g][1,8]naphthyridines 5(a–d), 6(a–d) and 2-chloroquinoline-4-amines 3(a–f) are reported and investigated with the aim of arriving at good fluorescent materials. Moreover, the effect of electron donor-acceptor substituent on fluorescence properties of all molecules has been investigated along with their fluorescent quantum yields. Furthermore we analyzed for band gap energy associated with HOMO-LUMO, through density functional (DFT M06-HF) studies. The experimental observations are in close agreement with the theoretical calculation. All the synthesized compounds were identified on the basis of their NMR, Mass spectral data analyses.

Recent developments in cyclodextrin functionalized monolithic columns for the enantioseparation of chiral drugs

The use of monolithic supports containing cyclodextrins (CDs) or their derivatives as chiral stationary phases (CSPs) has drawn much attention in the field of enantioseparations. The present review summarized the recent developments in CD functionalized monolithic columns. After introducing their classification in Section 1, various strategies applied to the preparation of the three types of CD functionalized monoliths, i.e. silica based monoliths, organic polymer based monoliths and organic-silica based hybrid monoliths, are thoroughly summarized in Section 2. Particularly, three different preparation strategies for covalently immobilizing CDs onto monoliths, including multi-step strategy, single-step strategy and one-pot strategy, are discussed. In the last section, the applications of CD functionalized monoliths in chiral separation of pharmaceuticals are highlighted.

A facile and efficient method of enzyme immobilization on silica particles via Michael acceptor film coatings: immobilized catalase in a plug flow reactor.

A novel method was developed for facile immobilization of enzymes on silica surfaces. Herein, we describe a single-step strategy for generating of reactive double bonds capable of Michael addition on the surfaces of silica particles. This method was based on reactive thin film generation on the surfaces by heating of impregnated self-curable polymer, alpha-morpholine substituted poly(vinyl methyl ketone) p(VMK). The generated double bonds were demonstrated to be an efficient way for rapid incorporation of enzymes via Michael addition. Catalase was used as model enzyme in order to test the effect of immobilization methodology by the reactive film surface through Michael addition reaction. Finally, a plug flow type immobilized enzyme reactor was employed to estimate decomposition rate of hydrogen peroxide. The highly stable enzyme reactor could operate continuously for 120h at 30°C with only a loss of about 36% of its initial activity.

4-Phenylaminomethyl-Benzeneboric Acid Modified Tip Extraction for Determination of Brassinosteroids in Plant Tissues by Stable Isotope Labeling–Liquid Chromatography–Mass Spectrometry

Monitoring brassinosteroids (BRs) has been of major interest of researchers as these substances play a crucial role in a variety of phytological processes in plants. However, the determination of endogenous BRs in plant tissue is still a challenging task due to their low abundance and the complex matrix of plant tissues. In this study, a single step strategy by combining tip extraction and in situ derivatization was proposed for BR analysis. In the proposed strategy, a mixed mode sorbent (C8-SO3H) in tip was modified with 4-phenylaminomethyl-benzeneboric acid (4-PAMBA) through cation exchange and hydrophobic interactions, and then used as a boronate affinity media to selectively capture and purify BRs from plant extract through the reaction of boric acid groups of 4-PAMBA and cis-diol on BRs. The BRs-4-PAMBA derivatives formed were easily eluted from the C8-SO3H tip by nullifying the ion exchange and hydrophobic interactions using ammonia acetonitrile, followed by LC-MS/MS analysis. BR standards, isotopically labeled with d5-4-phenylaminomethyl-benzeneboric acid (4-PAMBA-d5) were introduced to improve the assay precision of LC-MS/MS. Under the optimized conditions, the overall process could be completed within 1 h, which is greatly improved in speed compared with previously reported protocols. In addition, the detection sensitivities of labeled BRs were improved by over 2000-fold compared with unlabeled BRs, thus the consumption of plant materials was reduced to 50 mg. Finally, the proposed method was applied for the investigation of BRs response in rice toward Cd stress.

Bio-template Route for the Facile Fabrication of TiO2@Bacillus subtilis Composite Particles and Their Application for the Degradation of Rhodamine B

The Bacillus subtilis was used to synthesize the TiO2@Bacillus subtilis composite particles via a single-step strategy based on electrostatic interaction driving self-assembling heterocoagulation. Such materials had a rod-shaped microstructure with uniform size (1.4 +/- A 0.1 mu m in length; 450 +/- A 50 nm in width), and the removal ratio of rhodamine B was approximately 89 %. [GRAPHICS] .

Heterogeneous, three-dimensional texturing of graphene.

We report a single-step strategy to achieve heterogeneous, three-dimensional (3D) texturing of graphene and graphite by using a thermally activated shape-memory polymer substrate. Uniform arrays of graphene crumples can be created on the centimeter scale by controlling simple thermal processing parameters without compromising the electrical properties of graphene. In addition, we show the capability to selectively pattern crumples from otherwise flat graphene and graphene/graphite in a localized manner, which has not been previously achievable using other methods. Finally, we demonstrate 3D crumpled graphene field-effect transistor arrays in a solution-gated configuration. The presented approach has the capability to conform onto arbitrary 3D surfaces, a necessary prerequisite for adaptive electronics, and will enable facile large-scale topography engineering of not only graphene but also other thin-film and 2D materials in the future.

Efficient and cost-effective generation of mature neurons from human induced pluripotent stem cells.

For years, our ability to study pathological changes in neurological diseases has been hampered by the lack of relevant models until the recent groundbreaking work from Yamanaka's group showing that it is feasible to generate induced pluripotent stem cells (iPSCs) from human somatic cells and to redirect the fate of these iPSCs into differentiated cells. In particular, much interest has focused on the ability to differentiate human iPSCs into neuronal progenitors and functional neurons for relevance to a large number of pathologies including mental retardation and behavioral or degenerative syndromes. Current differentiation protocols are time-consuming and generate limited amounts of cells, hindering use on a large scale. We describe a feeder-free method relying on the use of a chemically defined medium that overcomes the need for embryoid body formation and neuronal rosette isolation for neuronal precursors and terminally differentiated neuron production. Four days after induction, expression of markers of the neurectoderm lineage is detectable. Between 4 and 7 days, neuronal precursors can be expanded, frozen, and thawed without loss of proliferation and differentiation capacities or further differentiated. Terminal differentiation into the different subtypes of mature neurons found in the human brain were observed. At 6-35 days after induction, cells express typical voltage-gated and ionotrophic receptors for GABA, glycine, and acetylcholine. This specific and efficient single-step strategy in a chemically defined medium allows the production of mature neurons in 20-40 days with multiple applications, especially for modeling human pathologies.

Electreted polyetherimide–silica fibrous membranes for enhanced filtration of fine particles

Development of technologies for air filtration and purification is critical to meet the global challenges of threatened human health and accelerated greenhouse effect, especially for point-of-use applications. Here, we report a novel electreted polyetherimide–silica (PEI–SiO2) fibrous membrane by a single-step strategy to achieve effective filtration of fine particles. The hierarchical structured PEI–SiO2 membranes were endowed with promising superhydrophobicity with a water contact angle of 152°, allowing their better self-cleaning performance compared with commercial polypropylene (PP) filter media. Morphology, electric charge property, porous structure, and filtration performance could be regulated by tuning the type and concentration of electrets as well as the solution properties. Furthermore, unlike the commercial PP-based filter media, the as-prepared membranes can be treated at 200°C for 30min without sacrificing filtration efficiency (99.992%) and pressure drop (61Pa) owing to the combined contribution of polarization and space charges. We anticipate that this promising electreted fibrous medium will act as a core part of numerous air filtration systems, including ultra-low penetration air filters, clean room, respirator, and protective clothing.

Specialized transduction designed for precise high-throughput unmarked deletions in Mycobacterium tuberculosis.

ABSTRACTSpecialized transduction has proven to be useful for generating deletion mutants in most mycobacteria, including virulent Mycobacterium tuberculosis. We have improved this system by developing (i) a single-step strategy for the construction of allelic exchange substrates (AES), (ii) a temperature-sensitive shuttle phasmid with a greater cloning capacity than phAE87, and (iii) bacteriophage-mediated transient expression of site-specific recombinase to precisely excise antibiotic markers. The methods ameliorate rate-limiting steps in strain construction in these difficult-to-manipulate bacteria. The new methods for strain construction were demonstrated to generalize to all classes of genes and chromosomal loci by generating more than 100 targeted single- or multiple-deletion substitutions. These improved methods pave the way for the generation of a complete ordered library of M. tuberculosis null strains, where each strain is deleted for a single defined open reading frame in M. tuberculosis.

Single-step generation of gene knockout-rescue system in pluripotent stem cells by promoter insertion with CRISPR/Cas9

Specific gene knockout and rescue experiments are powerful tools in developmental and stem cell biology. Nevertheless, the experiments require multiple steps of molecular manipulation for gene knockout and subsequent rescue procedures. Here we report an efficient and single step strategy to generate gene knockout-rescue system in pluripotent stem cells by promoter insertion with CRISPR/Cas9 genome editing technology. We inserted a tetracycline-regulated inducible gene promoter (tet-OFF/TRE-CMV) upstream of the endogenous promoter region of vascular endothelial growth factor receptor 2 (VEGFR2/Flk1) gene, an essential gene for endothelial cell (EC) differentiation, in mouse embryonic stem cells (ESCs) with homologous recombination. Both homo- and hetero-inserted clones were efficiently obtained through a simple selection with a drug-resistant gene. The insertion of TRE-CMV promoter disrupted endogenous Flk1 expression, resulting in null mutation in homo-inserted clones. When the inserted TRE-CMV promoter was activated with doxycycline (Dox) depletion, Flk1 expression was sufficiently recovered from the downstream genomic Flk1 gene. Whereas EC differentiation was almost completely perturbed in homo-inserted clones, Flk1 rescue with TRE-CMV promoter activation restored EC appearance, indicating that phenotypic changes in EC differentiation can be successfully reproduced with this knockout-rescue system. Thus, this promoter insertion strategy with CRISPR/Cas9 would be a novel attractive method for knockout-rescue experiments.

Tracking the Growth of Tadpole-shaped Aggregates by Scanning Electron Microscopy

A single-step strategy has been developed toward the synthesis of micrometer-sized, tadpole-like structures comprising a repeating sequence of a three-dimensional gold nanoparticle (AuNP)-aniline polymer-AuNP arrangement. The size and shape of the microstructure strongly depends on the concentration of aniline in the reaction solution. Herein, we describe the formation mechanism of the microstructure by focusing on the surface morphology.

Simple Preparation of Microstructure by Using an Organic-Inorganic Raspberry-like Hybrid as a Building Block

A single-step strategy has been developed for synthesizing a micrometer-sized structure by using the raspberry-like hybrid as a building block comprising a repeated sequence of a three-dimensional gold nanoparticle (AuNP)-aniline oligomer-AuNP arrangement. The hybrid holds a high density of highly dispersible AuNPs without any contact with each other, and therefore the microstructure has many nanometer-sized gaps between the adjacent AuNPs for both electrical and optical sensing. We have discussed how the formation mechanism of the microstructure is based on using the hybrid.

Incorporation of non-conjugated polymer chain in conjugated polymer matrix: A new single step strategy for free standing non-volatile polymer memory

A new single step strategy for polymer memory materials has been explored using free-standing polypyrrole (PPy) film in which non-conjugated polymer chains are incorporated as trap states during synthesis. The PPy film was synthesized by the acidic oxidation of 2,2′:5′,2′′-terpyrrole at the air/water interface. The free-standing PPy films show large hysteresis along with current peaks in opposite directions during current voltage (I–V) characteristics. Hysteric behavior has been utilized to show rewritable memory effect. Furthermore, once electrical state (high or low conduction state) is set, the state is stable for months in ambient condition unless the state is reset by applying a voltage of opposite polarity. Thus the PPy film can be used as read once memory. The memory effect of the film is due to the conformational changes of non-conjugated polymer chains in the PPy matrix. The changes in conformation were confirmed from UV–Vis and FTIR spectra. This new strategy leads free-standing film based all organic polymer memory devices at ultra low cost.

A detergent-free strategy for the reconstitution of active enzyme complexes from native biological membranes into nanoscale discs

BackgroundThe reconstitution of membrane proteins and complexes into nanoscale lipid bilayer structures has contributed significantly to biochemical and biophysical analyses. Current methods for performing such reconstitutions entail an initial detergent-mediated step to solubilize and isolate membrane proteins. Exposure to detergents, however, can destabilize many membrane proteins and result in a loss of function. Amphipathic copolymers have recently been used to stabilize membrane proteins and complexes following suitable detergent extraction. However, the ability of these copolymers to extract proteins directly from native lipid bilayers for subsequent reconstitution and characterization has not been explored.ResultsThe styrene-maleic acid (SMA) copolymer effectively solubilized membranes of isolated mitochondria and extracted protein complexes. Membrane complexes were reconstituted into polymer-bound nanoscale discs along with endogenous lipids. Using respiratory Complex IV as a model, these particles were shown to maintain the enzymatic activity of multicomponent electron transporting complexes.ConclusionsWe report a novel process for reconstituting fully operational protein complexes directly from cellular membranes into nanoscale lipid bilayers using the SMA copolymer. This facile, single-step strategy obviates the requirement for detergents and yields membrane complexes suitable for structural and functional studies.