Herringbone Structures Research Articles

Ferroelectric domain structure of lead-free potassium-sodium niobate ceramics

The complex domain structure of orthorhombic (K 0.5Na 0.5)NbO 3 (KNN) piezoelectric ceramics has been studied by SEM. The study was performed in samples prepared by microwave-hydrothermal synthesis. The identification of the domain structure has been afforded in KNN ceramics. Abnormal grain growth was observed in the microstructure of KNN ceramics, with an average grain size of 63 μm. Most of the ferroelectric domains were 90° type with square-net and herringbone structures alternating a– a and a– c configurations. In addition, 180° domains were also identified arranged in the common watermark pattern.

Concise Synthesis and Crystal Structure of [12]Cycloparaphenylene

Crystal clear: The title macrocycle was constructed by a nickel-mediated shotgun macrocyclization. The X-ray crystallographic structure of [12]CPP revealed a circular structure incorporating two cyclohexane molecules within the ring. The [12]CPP molecules were also found to crystallize into tubular and herringbone structures.

Stabilization of organic field-effect transistors by tert-butyl groups in dibenzotetrathiafulvalene derivatives

For a material for organic thin-film transistors, not only high mobility but also low threshold voltage and long-term stability are important requirements. In order to realize these properties, materials with relatively large oxidation potentials, namely weak donors, have been designed as p-channel organic semiconductors. Here we propose a different strategy; transistor properties of dibenzotetrathiafulvalene (DBTTF) are significantly improved by the introduction of tert-butyl groups. Although this chemical modification does not much change the ionization potential, small threshold voltage and stability over several months are attained together with the improved mobility, probably due to some kind of passivation effect of the bulky tert-butyl groups. In contrast, the systematic fluorine substitution rapidly diminishes the transistor performance. There are two kinds of herringbone structures with much different dihedral angles of about 50° and 130°, and the tert-butyl compound falls into the former category.

Passive micromixer for luminol-peroxide chemiluminescence detection

This paper reports a microchip with an integrated passive micromixer based on chaotic advection. The micromixer with staggered herringbone structures was used for luminol-peroxide chemiluminescence detection. The micromixer was examined to assess its suitability for chemiluminescence reaction. The relationship between the flow rate and the location of maximum chemiluminescence intensity was investigated. The light intensity was detected using an optical fiber attached along the mixing channel and a photon detector. A linear correlation between chemiluminescence intensity and the concentration of cobalt(ii) ions or hydrogen peroxide was observed. This microchip has a potential application in environmental monitoring for industries involved in heavy metals and in medical diagnostics.

Hydrodynamics and reaction studies in a layered herringbone channel

AbstractThe performance of a consecutive reaction of the type A→k1B→k2C was studied in two reactor configurations. A layered herringbone channel, which consists of two rectangular channels and a middle layer containing machined-through herringbone structures, is compared with an unstructured rectangular channel. It was found that when the reactants are not premixed before the inlet, the layered herringbone configuration shows an improved performance compared to the rectangular channel giving a 40% increase in the maximum amount of intermediate produced. The maximum concentration of intermediate is obtained at lower residence times, which indicates that reactor volume could be decreased compared to the rectangular channel. The maximum amount of intermediate and the conversion at which this maximum occurs is dependent also on the ratio (k2/k1) which in this work is 0.05. Good mixing characteristics and narrow residence time distribution (RTD) are responsible for the improved behaviour in the layered herringbone channel. When the reactants are premixed before the inlet the differences are more subtle, indicating that the improved reaction behaviour in the layered herringbone channel is mainly due to good mixing and to a smaller extent to narrow RTDs. Residence time distributions were calculated numerically via CFD and particle tracking methods. The RTDs for the layered herringbone channel were found to be narrower as compared to the rectangular one. The model of axial dispersion exchanging mass with a stagnant zone was used for the modelling of the RTD. It was found that the model parameters could be calculated directly from hydrodynamic data obtained from CFD calculations, without the need of particle tracking algorithms. Concepts from turbulent theory were employed for the calculation of an effective diffusion coefficient that replaced the stirring effect of the herringbones. This procedure greatly simplifies the theoretical calculation of RTDs and reaction conversions.

Surface deformation of amorphous silicon thin film on elastomeric substrate

Stiff thin layers on compliant substrates can generate various surface structures using equi-biaxial stress caused by large thermal expansion rate differences. We investigated the detailed understanding on the evolution of self-assembled wrinkle patterns of ultra-thin amorphous silicon (a-Si) layers on polydimethylsiloxane substrate. It turns out that the generation of various wrinkle patterns depends on the position of their orientation, film thicknesses, mechanical properties of the a-Si films, and the amount of pre-strain. The various self-assembled patterns include one-dimensional wavy patterns, randomly ordered two-dimensional structured patterns, and herringbone structures. The self-assembled wrinkles can be characterized by the wavelength and amplitude of the distinct structures: the amplitudes of the various patterns increase as the amount of pre-strain increases, while the wavelengths remain constant within our experimental ranges. The experimental results of the wavelengths and amplitudes for the wavy structured patterns of 270-nm-thick a-Si layer are in good agreement with the theoretical solutions of the single crystalline silicon (c-Si) model, which implies that the theoretical modeling of the deformation of c-Si film can be expandable to the case of a-Si film deformations.

Hydrothermal Syntheses and Structures of Lanthanide Coordination Polymers with 5-Aminoisophthalate and 1,10-Phenthroline

Two new lanthanide coordination polymers, [Ln2(APA)2(HAPA)2(phen)2] n [Ln = Pr (1), Eu (2); H2APA = 5-aminoisophthalic acid, phen = 1,10-Phenanthroline] have been synthesized by hydrothermal method, and characterized by single crystal X-ray diffraction, elemental analysis and IR spectra. Crystallographic data show that complexes 1 and 2 both crystallize in a triclinic system, space group $$ P\bar{1} $$ . The titled compounds own 2-D herringbone structures which are further constructed to form 3-D supramolecular structures by N–H···O and O–H···O hydrogen bondings. The thermogravimetric analyses were carried out to examine the thermal stability of the title complexes. And the photoluminescence property of 2 was investigated. In the title complexes 5-aminoisophthalic acids link the lanthanide ions to 2-D herringbone structures which are further constructed to form 3-D supramolecular structures. Two 3-D lanthanide supramolecular coordination polymers with high thermal stability have been synthesized by hydrothermal method.

THE EFFECT OF LARGE-SCALE MAGNETIC TURBULENCE ON THE ACCELERATION OF ELECTRONS BY PERPENDICULAR COLLISIONLESS SHOCKS

We study the physics of electron acceleration at collisionless shocks that move through a plasma containing large-scale magnetic fluctuations. We numerically integrate the trajectories of a large number of electrons, which are treated as test particles moving in the time dependent electric and magnetic fields determined from 2-D hybrid simulations (kinetic ions, fluid electron). The large-scale magnetic fluctuations effect the electrons in a number of ways and lead to efficient and rapid energization at the shock front. Since the electrons mainly follow along magnetic lines of force, the large-scale braiding of field lines in space allows the fast-moving electrons to cross the shock front several times, leading to efficient acceleration. Ripples in the shock front occuring at various scales will also contribute to the acceleration by mirroring the electrons. Our calculation shows that this process favors electron acceleration at perpendicular shocks. The current study is also helpful in understanding the injection problem for electron acceleration by collisionless shocks. It is also shown that the spatial distribution of energetic electrons is similar to in-situ observations (e.g., Bale et al. 1999; Simnett et al. 2005). The process may be important to our understanding of energetic electrons in planetary bow shocks and interplanetary shocks, and explaining herringbone structures seen in some type II solar radio bursts.

Automated Microfluidic Blood Lysis Protocol for Enrichment of Circulating Nucleated Cells

In this report the protocol for an automated microfluidic blood lysis device is detailed. Circulating nucleated cells (CNCs), including leukocytes and endothelial cells, provide an ideal platform for an updated status on the immune condition of an individual. The microfluidic protocol allows for enrichment of CNCs without selective cell loss and sample preparation variability due to user-mediated steps. Briefly, the protocol includes device fabrication, sample collection, device setup, and running blood through the microfluidic chamber. Within the device whole blood is rapidly mixed with deionized water for approximately 10 seconds in a 50 micron x 150 micron microfluidic channel. In this time span erythrocytes are lysed due to hypotonic conditions. Herringbone structures on the bottom of the channel ensure thorough mixing and exposure of cells to a constant environment. Remaining cells are returned to isotonic conditions at the exit of the device, fixed using 2% paraformaldehyde, centrifuged to separate erythrocyte debris from CNCs, and suspended in flow buffer for staining and analysis by flow cytometry. Results show clean flow cytometry scatter plots with CNC populations saved. Significance of this device and protocol comes in the study and understanding of disease pathogenesis by analysis of CNC populations. Hence, automation, effectiveness, and simplicity of the microfluidic protocol are demonstrated.

Automated Microfluidic Blood Lysis Protocol for Enrichment of Circulating Nucleated Cells

In this report the protocol for an automated microfluidic blood lysis device is detailed. Circulating nucleated cells (CNCs), including leukocytes and endothelial cells, provide an ideal platform for an updated status on the immune condition of an individual. The microfluidic protocol allows for enrichment of CNCs without selective cell loss and sample preparation variability due to user-mediated steps. Briefly, the protocol includes device fabrication, sample collection, device setup, and running blood through the microfluidic chamber. Within the device whole blood is rapidly mixed with deionized water for approximately 10 seconds in a 50 micron x 150 micron microfluidic channel. In this time span erythrocytes are lysed due to hypotonic conditions. Herringbone structures on the bottom of the channel ensure thorough mixing and exposure of cells to a constant environment. Remaining cells are returned to isotonic conditions at the exit of the device, fixed using 2% paraformaldehyde, centrifuged to separate erythrocyte debris from CNCs, and suspended in flow buffer for staining and analysis by flow cytometry. Results show clean flow cytometry scatter plots with CNC populations saved. Significance of this device and protocol comes in the study and understanding of disease pathogenesis by analysis of CNC populations. Hence, automation, effectiveness, and simplicity of the microfluidic protocol are demonstrated.

Residence time distributions in microchannels: Comparison between channels with herringbone structures and a rectangular channel

Residence time distributions (RTD) have been determined numerically and experimentally for channels with and without herringbone structures. Computational fluid dynamics (CFD) and particle tracking with random walk diffusion were employed for the numerical calculation of the RTD. The axial dispersion exchanging mass with a stagnant zone model was shown to fit the particle tracking data for the channels with staggered herringbone structures. This model provides a simpler method for RTD characterisation. Experimental RTD measurements were performed by monitoring the concentration of a tracer dye by means of a LED-photodiode system. For all cases, the calculations agreed well with experiments. The results show that for low Peclet numbers (Pe < 10 2) the use of herringbone structures does not have an impact on the RTD, however at high Peclet numbers (Pe > 10 2), channels with herringbone structures exhibit a narrower RTD than a plain channel of the same dimensions. Thus, at high Pe, inclusion of herringbones to the bottom floor of rectangular channels allows the increase in channel dimensions without adverse effect on the RTD behaviour or reaction performance.

Morphology influence of the oxidation kinetics of carbon nanofibers

This paper reports the stability and oxidation rate of five types of carbon nanofiber (CNF) with distinctly different orientation of their graphite sheets based on conversion to CO 2 when heated in the presence of oxygen. A non-isothermal technique was used to determine the oxidation kinetic parameters including the activation energy ( E a). Graphite shows a similar activation energy ( E a = 158 kJ/mol −1) to CNF with longitudinal alignment ( E a = 156 kJ/mol −1). CNF type herringbone ( E a = 126 kJ/mol −1) and platelet ( E a = 145 kJ/mol −1) show the lowest oxidation resistance which improved dramatically after a heat treatment at 3023 K of the herringbone ( E a = 216 kJ/mol −1) and platelet ( E a = 174 kJ/mol −1) structures.

Synthesis and luminescent properties of pyrenylvinylene-substituted tripylborane

Abstract A novel luminescent compound, bis((E)-2-pyren-1-yl-vinyl)-2,4,6-triisopropylphenylborane (3) was synthesized by hydroboration reaction and was fully characterized. The obtained compound was further investigated by single-crystal X-ray diffraction analysis and DFT calculations. The extended structure tells us their herringbone structures with closely faced pairs of the molecules. Comparing the photoluminescent spectra between solution-state and solid state, the spectrum of the solid state of the compound 3 exhibited dramatically red-shifted fluorescent emission. This change also supports the efficient π-stacking behavior of the compound 3 .

Electron backscatter diffraction mapping of herringbone domain structures in tetragonal piezoelectrics

Herringbone domain structures have been mapped using electron backscatter diffraction in two tetragonal piezoelectrics: lead zirconate titanate [Pb(Zr,Ti)O3] and bismuth ferrite–lead titanate [(PbTi)0.5(BiFe)0.5O3]. Analysis of the domain misorientations across the band junctions shows that the structures correspond very well to crystallographic models. High resolution mapping with a 20nm step size allowed the crystal rotation across one of these band junctions in lead zirconate titanate to be studied in detail and allowed an improved estimation of the peak strain at the junction, of 0.56GPa. The significance of this for crack nucleation and propagation in such materials is discussed.

Growth of carbon nanofibers on carbon fabric with Ni nanocatalyst prepared using pulseelectrodeposition

The pulse electrodeposition (PED) technique was utilized to deposit nanosized(≤10 nm) Ni catalysts on carbon fabric (CF). Via an in situ potential profile, the PED techniquecan control the Ni catalyst loading, which is an important parameter for the growth ofcarbon nanofibers (CNFs) on CF. The preparation of CNF-coated CF (carpet-like CF) wascarried out in a thermal chemical vapor deposition system with an optimum loading of Nicatalysts deposited in the PED pulse range from 20 to 320 cycles. CNFs grown at813 K using different pulse cycles had a narrow diameter distribution, around15 ± 5 nmto 29 ± 7 nm; they have a hydrophobic surface, like lotus leaves. Transmission electron microscopyimages confirmed the graphene structural transformation of CNFs with the growthtemperature. Solid wire CNFs were initially grown at 813 K with graphene edges exposedon the external surface. At elevated growth temperatures (1073 and 1173 K), bamboo-likeCNFs were obtained, with herringbone structures and intersectional hollow cores.

STM investigation of the dependence of alkane and alkane (C 18H 38, C 19H 40) derivatives self-assembly on molecular chemical structure on HOPG surface

Alkane molecules and their derivatives are composed of alkyl chain and functional groups that dominate the interactions of intermolecule and molecule/substrate and result in different self-assemblies on solid surface. In the present paper, the self-assemblies of alkanes and alkane (C 18H 38, C 19H 40) derivatives are studied on HOPG surface at room temperature in ambient conditions by scanning tunneling microscopy (STM) to understand the structure and stability of these self-assemblies and to reveal the dependence of their self-assemblies on their chemical structures. It is found that the alkane molecules with short alkyl chains such as tridecane (C 13H 28), tetradecane (C 14H 30) and pentadecane (C 15H 32) can form lamellar structures on HOPG and be steadily imaged by STM. On the other hand, linear or herringbone structures can be observed in the self-assemblies formed by a series of derivatives of C 18H 38 and C 19H 40. The results are discussed based on STM results to understand the structures and structural stability of alkane molecular self-assemblies.

Synthesis of recombinant human parainfluenza virus 1 and 3 nucleocapsid proteins in yeast Saccharomyces cerevisiae

Human parainfluenza virus types 1 and 3 (HPIV1 and HPIV3, respectively), members of the virus family Paramyxoviridae, are common causes of lower respiratory tract infections in infants, young children, the immunocompromised, the chronically ill, and the elderly. In order to synthesize recombinant HPIV1 and HPIV3 nucleocapsid proteins, the coding sequences were cloned into the yeast Saccharomyces cerevisiae expression vector pFGG3 under control of GAL7 promoter. A high level of recombinant virus nucleocapsid proteins expression (20–24 mg l −1 of yeast culture) was obtained. Electron microscopy demonstrated the assembly of typical herring-bone structures of purified recombinant nucleocapsid proteins, characteristic for other paramyxoviruses. These structures contained host RNA, which was resistant to RNase treatment. The nucleocapsid proteins were stable in yeast and were easily purified by caesium chloride gradient ultracentrifugation. Therefore, this system proved to be simple, efficient and cost-effective, suitable for high-level production of parainfluenza virus nucleocapsids as nucleocapsid-like particles. When used as coating antigens in an indirect ELISA, the recombinant N proteins reacted with sera of patients infected with HPIV1 or 3. Serological assays to detect HPIV-specific antibodies could be designed on this basis.

Spontaneous formation of one-dimensional ripples in transit to highly ordered two-dimensional herringbone structures through sequential and unequal biaxial mechanical stretching

The authors report the formation of various submicron wrinkle patterns and their transition from one-dimensional (1D) ripples to two-dimensional (2D) herringbone structures on poly(dimethylsiloxane) films. Using mechanical force they can separately control the amount and timing of strain applied to the substrate on both planar directions (either simultaneously or sequentially), which appears to be critical to maneuver the pattern formation in real time. They demonstrate reversible transitions from flat to 1D ripple, to ripple with bifurcation, to ripple/herringbone mixed features, and to well-controlled formation of a highly ordered zigzag-based 2D herringbone structures.

Generation of henipavirus nucleocapsid proteins in yeast Saccharomyces cerevisiae

Hendra and Nipah viruses are newly emerged, zoonotic viruses and their genomes have nucleotide and predicted amino acid homologies placing them in the family Paramyxoviridae. Currently these viruses are classified in the new genus Henipavirus, within the subfamily Paramyxovirinae, family Paramyxoviridae. The genes encoding HeV and NiV nucleocapsid proteins were cloned into the yeast Saccharomyces cerevisiae expression vector pFGG3 under control of GAL7 promoter. A high level of expression of these proteins (18–20 mg l −1 of yeast culture) was obtained. Mass spectrometric analysis confirmed the primary structure of both proteins with 92% sequence coverage obtained using MS/MS analysis. Electron microscopy demonstrated the assembly of typical herring-bone structures of purified recombinant nucleocapsid proteins, characteristic for other paramyxoviruses. The nucleocapsid proteins revealed stability in yeast and can be easily purified by cesium chloride gradient ultracentrifugation. HeV nucleocapsid protein was detected by sera derived from fruit bats, humans, horses infected with HeV, and NiV nucleocapsid protein was immunodetected with sera from, fruit bats, humans and pigs. The development of an efficient and cost-effective system for generation of henipavirus nucleocapsid proteins might help to improve reagents for diagnosis of viruses.

Multi-scale phase field approach to martensitic transformations

Because of its flexibility in treating complex geometries and topological changes, the phase field method has been used widely in modeling microstructural evolution during various phase transformations, grain growth and, most recently, plastic deformations. We review formulations and applications of the method in the context of martensitic transformations (MTs). Examples are chosen to illustrate the capabilities of the method at both mesoscopic and microscopic length scales. At the mesoscopic level we present simulation predictions on structural configurations of critical nuclei generated by homogeneous nucleation through Langevin thermal fluctuations under large undercooling, formation of herringbone structures by autocatalytic growth, and microstructural evolution and transformation hysteresis in a polycrystalline alloy under uniaxial stresses. At the microscopic level we discuss new developments in phase field model of dislocation dissociation and core structure and phase field model of mislocation—a new elementary defect introduced to describe the initiation and growth of martensite.