Broad Ring Research Articles

Influence of fluorine substitution on the morphology and structure of hydroxyapatite nanocrystals prepared by hydrothermal method

Hydroxyapatite (HAp) nanocrystals with different levels of fluorine substitution (P/F = 0, 6, 4 and 2) on the OH sites were produced via hydrothermal method. The fluorine substitution was found to alter the morphology of crystals appreciably. The aspect ratio and the crystallinity of HAp crystals increased with increasing fluorine substitution. The presence of broad ring and hallow ring patterns in electron diffraction suggests the low-crystalline nature of HAp crystals. With increasing fluorine substitution, the diffraction patterns exhibited discrete rings and numerous diffraction spots, implying the increased crystallinity. Raman spectra from the HAp nanoparticles also support the less-crystalline nature of the pristine HAp and the enhanced crystallization by fluorine substitution. In HAp crystals processed with no fluorine substitution, surface energy and planar Ca2+ density are less sensitive to the crystallographic orientation because of its low-crystalline nature, favoring equi-axed or slightly elongated particles. The addition of fluorine apparently increased the crystallinity, enhancing the orientation dependent growth and accordingly the aspect ratio. Osteoblast proliferation was observed to be enhanced by fluorine substitution in HAp. In vitro biological data support that the excellent osteoblastic cell viability and functional activity of the fluoridated apatite.

Radial n–i–p structure silicon nanowire‐based solar cells on flexible stainless steel substrates

AbstractRadial n–i–p structure silicon nanowires‐(SiNWs) based solar cells on flexible stainless steel substrates have been fabricated by plasma‐enhanced chemical vapor deposition (PECVD). The highest open‐circuit voltage (Voc) and short‐circuit current density (Jsc) for AM 1.5 illumination were 0.62 V and 13.36 mA cm−2, respectively, at a maximum power conversion efficiency of 3.56%. The optical reflectance of the SiNWs solar cells over a broad rang of wavelengths (300–1000 nm) is reduced by ∼80% in average compared to planar silicon thin film cells. The external quantum efficiency (EQE) measurements show that the EQE response of SiNWs solar cells is improved greatly in the wavelength range of 550–750 nm compared to corresponding planar silicon thin film solar cells.

Focused ion beam assisted investigations of Al interface in polythiophene:Fullerene solar cells

The aluminum (Al) electrode interface in regio-regular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) solar cells is probed using transmission electron microscopy (TEM) techniques. A state-of-the-art TEM sample preparation including in-situ lift-out is carried out using a dual focused ion beam (FIB) on two types of devices—one without annealing and one after annealing at 120°C for 20min. The vertical morphology is studied by crossectional TEM. It is found that upon annealing the thickness of both the Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) PEDOT:PSS and P3HT/PCBM layers decreased significantly from 21±2nm to 16±1nm and 130±2 to 80±1nm, respectively. Through bright field micrographs a mixed layer between the Al electrode and the organic active layer is clearly observed in both methods of device preparations. A nanobeam mode is utilized to collect nanobeam electron diffraction (NBD) pattern in different layers of the device. In the Al layer, discrete diffraction spots from the atomic planes are observed, indicating a single crystal structure of Al. A broad ring diffraction pattern is observed in the P3HT/PCBM layer indicated disorder in the organic layer. A mixture of diffraction spots and an amorphous-like pattern is collected from the mixed region implying diffusion of Al into the organic layer. Elemental mapping results also confirmed that upon annealing Al diffused into the organic layer. Bright field TEM images of annealed devices show a well-contacted interface between Al and the mixed layer as compared to the unannealed devices. The effect of Al contact resistance before and after annealing is studied using the vertical transmission line model (TLM). It is found that by annealing after Al evaporation, the contact resistivity decreased by 38%. The results are consistent with the observation that upon annealing Al atoms diffused into the organic layer and established a mixed region which helps to decrease the contact resistance between the Al electrode and P3HT:PCBM active layer.

TEM study of β′ precipitate interaction mechanisms with dislocations and β′ interfaces with the aluminium matrix in Al–Mg–Si alloys

Abstract The interaction mechanisms between dislocations and semi-coherent, needle-shaped β′ precipitates in Al–Mg–Si alloys have been studied by High Resolution Transmission Electron Microscopy (HRTEM). Dislocation loops appearing as broad contrast rings around the precipitate cross-sections were identified in the Al matrix. A size dependency of the interaction mechanism was observed; the precipitates were sheared when the longest dimension of their cross-section was shorter than approximately 15 nm, and looped otherwise. A more narrow ring located between the Al matrix and bulk β′ indicates the presence of a transition interface layer. Together with the bulk β′ structure, this was further investigated by High Angle Annular Dark Field Scanning TEM (HAADF-STEM). In the bulk β′ a higher intensity could be correlated with a third of the Si-columns, as predicted from the published structure. The transition layer incorporates Si columns in the same arrangement as in bulk β′, although it is structurally distinct from it. The Z-contrast information and arrangement of these Si-columns demonstrate that they are an extension of the Si-network known to structurally connect all the precipitate phases in the Al–Mg–Si(–Cu) system. The width of the interface layer was estimated to about 1 nm.

Drying dissipative structures of lightly cross-linked poly(2-vinyl pyridine) cationic gel spheres stabilized with poly(ethylene glycol) in the deionized aqueous suspension

Drying dissipative patterns of deionized and colloidal crystal-state suspensions of the cationic gel spheres of lightly cross-linked poly(2-vinyl pyridine) stabilized with poly(ethylene glycol) were observed on a cover glass, a watch glass, and a Petri glass dish. Convectional patterns were recognized with the naked eyes. The broad rings were observed in the drying pattern and their size and width decreased as gel concentration decreased. Formation of the monodispersed agglomerated particles and their ordered arrays were observed. This work clarified the formation of the drying microscopic structures of (a) ordered rings, (b) flickering ordered spoke-lines, (c) net structure, and (d) lattice-like ordered structures of the agglomerated particles. The ordering of the agglomerated particles of the cationic gel spheres is similar to that of the anionic thermo-sensitive gel spheres of poly(N-isopropyl acrylamide). The role of the electrical double layers around the agglomerated particles and the interaction of the particles with the substrates during dryness are important for the ordering. The microscopic drying patterns of gel spheres were different from those of linear-type polymers and also from typical colloidal hard spheres, though the macroscopic patterns such as broad ring formation at the edges were similar to each other. The addition of sodium chloride shifted the microscopic patterns from lattice to net structures.

Drying dissipative structures of thermosensitive gel spheres of poly (N-isopropylacrylamide). Influence of gel size

Drying dissipative patterns of de-ionized suspensions (colloidal crystal-state at high concentrations) of the thermosensitive gels of poly (N-isopropylacrylamide) with various sizes (ca. 400–1,500 nm in diameter at 20 °C) were observed at 20 and 45 °C on a cover glass, a watch glass, and a Petri glass dish. The broad rings were observed and their size decreased as gel concentration decreased. Formation of the monodispersed agglomerated particles and their ordered arrays were observed irrespective of gel size. The macroscopic flickering spoke-like patterns were observed for the gel spheres from 70 to 600 nm in diameter at 20 °C, but almost disappeared for extremely large spheres, poly(N-isopropylacrylamide)(1500-5). This work clarified the formation of the drying microscopic structures of (a) ordered rings, (b) flickering ordered spoke lines, (c) net structure, and (d) lattice-like ordered structures of the agglomerated particles. The ordered rings became rather vague as gel size increased. The large net structures formed so often for large gels. Size effect on the lattice patterns was not recognized so clearly. The role of the electrical double layers around the agglomerated particles and the interaction of the particles with the substrate surfaces during dryness are important for the ordering. The microscopic drying patterns of gel spheres were quite different from those of linear type polymers and also from typical colloidal hard spheres, though the macroscopic patterns such as broad ring formation at the edges of the dried film were similar to each other.

Drying dissipative structures of thermo-sensitive gel spheres of poly(N-isopropylacrylamide). Influence of degree of cross-linking of the gels

Drying dissipative patterns of de-ionized suspensions (colloidal crystal state above the critical concentrations of crystallization) of the thermo-sensitive gels of poly(N-isopropylacrylamide) with degrees of cross-linking of 10% and 2% (pNIPAm(200–10) and pNIPAm(200–2)) were observed at 20 °C and 45 °C on a cover glass, a watch glass, and a Petri glass dish. The broad rings were observed, and their size decreased as micro-gel concentration decreased. Formation of the monodispersed agglomerated particles and their ordered arrays were observed. Microscopic drying structures of (a) flickering ordered spoke-lines, (b) ordered rings, (c) net structure, and (d) lattice-like ordered structures of the agglomerated particles are observed. The net and lattice structures formed more favorably at high degrees of cross-linking, at high concentrations of the gels, and/or high temperatures. By the addition of sodium chloride, very large dendrite-like and net structures of the large agglomerated particles formed at 20 °C and 45 °C, respectively. Importance of the cooperated convectional flow of the agglomerated particles during the drying processes is supported for the ordered array formation. The role of the electrical double layers around the agglomerated particles and the interaction of the particles with the substrate surfaces during dryness are also important for the ordering. The microscopic drying patterns of gel spheres were different from those of linear type polymers and also from typical colloidal spheres, though the macroscopic patterns of gel system such as broad ring formation at the edges of the dried film were similar to other two systems.

Entomopathogenic Fungi as Microbial Biocontrol Agent

An attractive alternative method to chemical pesticides is the microbial biocontrol (MBCAs) agents. They are the natural enemies devastating the pest population with no hazard effects on human health and the environment. Entomopathogenic fungi has an important position among all the biocontrol agents because of its route of pathogenicity, broad host rang and its ability to control both sap sucking pests such as mosquitoes and aphids as well as pests with chewing mouthparts, yet they only cover a small percentage of the total insecticide market. Improvements are needed to fulfill the requirements for high market share. Entomopathogenic fungi differ from other microorganisms in their infection process: they directly breach the cuticle to enter the insect hemocoel, while other microorganisms enter by ingestion through mouth and then cause disease. Insect cuticle is mainly composed of chitin and protein surrounded by wax, lipid layer or fatty acids. Fungal pathogenesis mainly starts with the secretion of cuticle degrading enzymes. Some important and well known cuticle degrading enzymes are chitinase, protease and lipase which can degrade chitin, protein and lipid of the cuticle, respectively. In this review we collected literatures from different sources and we arranged them in a such a way to better to understand the process of insect pathogenicity of entomopathogenic fungi and to find ways to improve the virulence of wild strain fungi to shorten the killing time of the pest and to commercialize the entomopathogenic fungi. In this way, the market share of the fungal entomopathogenic fungi will increase and a decrease in the usage of synthetic chemical pesticides will automatically follow.

The nuclear polycyclic aromatic hydrocarbon emission of merger system NGC 1614: rings within rings

It is important to understand the interplay between nuclear star formation and nuclear activity when studying the evolution of gas-rich galaxy mergers. We present here new spatially resolved L-band integral field unit observations of the inner kpc of the luminous infrared galaxy NGC 1614. A broad ring of 3.3-μm polycyclic aromatic hydrocarbon (PAH) emission is found at a distance of approximately 200 pc from the core. This ring overlaps with a previously established star-forming ring detected with Paα and radio continuum observations, but peaks outside it, especially if determined using the PAH equivalent width. Using the characteristics of the PAH emission and the ionized gas emission, we argue that NGC 1614 features an outward propagating ring of star formation, where the equivalent width of the PAH emission localizes the regions where the current star formation is just expanding into the molecular gas outward of the nucleus. The core itself shows a highly luminous, slightly resolved (at ∼80 pc) L-band continuum source. We find no evidence of active galactic nucleus (AGN) activity and rule out the presence of an obscured AGN using L-band diagnostics. Furthermore, we detect the likely companion galaxy from archival Hubble Space Telescope/Advanced Camera for Surveys (ACS) imaging. The star formation and dynamical characteristics of the system are consistent with a relatively major merger just after its second passage. An outstanding question is how a gas-rich advanced merger such as this one, with strong luminous infrared galaxies level nuclear starburst and major-merger-like tidal features, has not yet developed an active nucleus.

Drying dissipative structures of thermo-sensitive gel spheres of poly(N-isopropylacrylamide) with low degree of cross-linking

Drying dissipative patterns of deionized suspensions (colloidal crystal state at high concentrations) of the thermo-sensitive gels of poly(N-isopropylacrylamide) with low degree of cross-linking of 0.5% (318 nm and 116 nm in the hydrodynamic diameter at 25 °C and 45 °C) were observed at 20 °C and 45 °C on a cover glass, a watch glass and a Petri glass dish. The broad rings were observed and their size decreased as micro-gel concentration decreased. Formation of the monodispersed agglomerated particles and their ordered arrays were observed. This work clarified the formation of the drying microscopic structures of (a) flickering ordered spoke-lines, (b) ordered rings, (c) net structure, and finally (d) lattice-like ordered structures of the agglomerated particles. The net and lattice structures formed more favorably at higher temperatures and/or higher degree of cross-linking of the gels. Importance of the convectional flow of the agglomerated particles during the drying processes is supported for the ordered array formation. The role of the electrical double layers around the agglomerated particles and the interaction of the particles with the substrate surfaces during dryness are also important for the ordering. The microscopic drying patterns of gel spheres were quite different from those of linear-type polymers and also from typical colloidal spheres, though the macroscopic patterns such as broad ring formation at the edges of the dried film were similar to each other.

Gabbro in Wanning, Hainan Island: LA-ICP-MS Chronometry and its Geological Significance

Gabbro is mostly the result of partly melting from mantle rock, and its formation is usually related with extension tectonic, the research work on Triassic gabbro from Hainan island has important instruction significance to its tectonic background. System chronometry and geochemistry research on hornblende gabbro in Wanning area was made in this paper, and its tectonic significance is to be discussed. The LA-ICP-MS zircon U-Pb age dating result shows that the gabbro in Wanning area was formed in 241±1.7Ma. The major and trace elements characteristic shows that the rocks belong to alkaline series, enrichment in light REE (LREE/HREE＝7.22-8.5) and LILE Rb, Th, and Sr, Ba while depleted in HFSE Nb, Ta and Zr, Hf. The Wanning gabbro exhibits a narrow range of εNd(t) values (1.59-1.76), and a broad rang 87Sr/86Sr initial ratios(0.70633-0.70964). The tectonic background of Wanning gabbro is intracontinental extensional setting, and its geochemistry characteristic declare that there was an ancient ocean basin existed, and maybe one branch of the ancient eastern Tethys ocean. The formation age and tectonic setting declare that the ancient ocean basin was disappeared at least before 241Ma.

Multi-wavelength modeling of the spatially resolved debris disk of HD 107146

(abridged) We aim to constrain the location, composition, and dynamical state of planetesimal populations and dust around the young, sun-like (G2V) star HD 107146}. We consider coronagraphic observations obtained with the Advanced Camera for Surveys (HST/ACS) onboard the HST in broad V and broad I filters, a resolved 1.3mm map obtained with the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), Spitzer/IRS low resolution spectra, and the spectral energy distribution (SED) of the object at wavelengths ranging from 3.5micron to 3.1mm. We complement these data with new coronagraphic high resolution observations of the debris disk using the Near Infrared Camera and Multi-Object Spectrometer (HST/NICMOS) aboard the HST in the F110W filter. The SED and images of the disk in scattered light as well as in thermal reemission are combined in our modeling using a parameterized model for the disk density distribution and optical properties of the dust. A detailed analytical model of the debris disk around HD 107146 is presented that allows us to reproduce the almost entire set of spatially resolved and unresolved multi-wavelength observations. Considering the variety of complementary observational data, we are able to break the degeneracies produced by modeling SED data alone. We find the disk to be an extended ring with a peak surface density at 131AU. Furthermore, we find evidence for an additional, inner disk probably composed of small grains released at the inner edge of the outer disk and moving inwards due to Poynting-Robertson drag. A birth ring scenario (i.e., a more or less broad ring of planetesimals creating the dust disk trough collisions) is found to be the most likely explanation of the ringlike shape of the disk.

Dissipative crystallization of sodium salts of poly (d-glutamic acid), poly (l-glutamic acid), and their low molecular weight analogs

Drying dissipative patterns were observed at room temperature on a cover glass, a watch glass, and a Petri glass dish during the course of dryness of aqueous solution of sodium salts of poly (d-glutamic acid), poly (l-glutamic acid), and their low molecular weight analogs, monosodium d-glutamate, monosodium l-glutamate, and monosodium dl-glutamate. The low molecular weight analogs were hygroscopic and their drying patterns were observed in a dry box coexisted with the bags of desiccant. The broad rings, which are the typical macroscopic drying patterns, were observed for all the samples. Optical isomeric effects on the drying patterns were not recognized. Spherulite (or hedrite) and rod-like crystals from the assemblies of helical main chains of the polymers are formed mainly at the inner area from the broad ring (except central area) and the broad ring area, respectively. Coexistence of sodium chloride enhanced the crystal structures by the cooperative interactions between the polymers and the salts. The typical dissipative crystallization such as accumulation, segregation, and orientation effects of crystals were observed in the drying patterns.

Resisting motorization in Guangzhou

Private motorization has accompanied unprecedented urbanization in China, as a matter of public policy. Planning at the provincial and city levels has supported the rapid build-up of the private car fleet in major cities through the development of regional and urban highway networks, higher capacity local streets and much higher standards for car parking in new developments. By contrast, urban planning until 1994 concentrated on the building of community and the support for a non-motorized lifestyle. Guangzhou experienced particularly rapid city-building during this period because it was at the centre of the market reforms launched in 1978. The communities that were built form a broad ring around the historic core of the city, constituting one of the most significant obstacles to government ambitions to maintain the recent growth rates in car ownership. Guangyuan and Jiangnanxi are examples of such middle-class, home-owning communities where daily life remains almost exclusively non-motorized. Self-organized groups in the community are increasingly vocal and active in their demands to enhance local environmental quality and restrict local motorization. Local municipal authorities, although increasingly active and autonomous, try to strike a balance between government objectives and local demands. The application of motorization illustrates the growing gap between high-level policy and grassroots urban planning in Guangzhou.

Dissipative crystallization of aqueous mixtures of potassium salts of poly(riboadenylic acid) and poly(ribouridylic acid)

Dissipative drying patterns of aqueous mixtures of potassium salts of poly(riboadenylic acid) (KPolyA) and poly(ribouridylic acid) (KPolyU) were studied on a cover glass, a watch glass and a glass dish at room temperature. Accumulation of the polymers forming the broad rings near the outside edge and the inner area of the dried film was observed. The fine multiple ring structures formed when the affinity of the polymer with the substrate is strong. Microscopic drying patterns changed drastically depending on the location in the dried film. Microscopic drying patterns were mainly dendritic long rods and sword (halberd)-like rods. They are assigned to the crystals of double-stranded and triple-stranded helices of the A:U and A:2U complexes, respectively. Cross-like drying patterns are also observed originated from the salt-polymer interaction.

FORMATION OF MOONLETS IN SATURN’S RINGS: THE ROLE OF THE CONSTRUCTIVE INTERFERENCE OF LIN-SHU-TYPE CIRCULAR AND SPIRAL DENSITY WAVES

Localized kilometer-sized propeller features, recently detected in CASSINI images of Saturn's A ring, may be interpreted as signatures of small hundred-meter-sized moonlets embedded within the broad ring. We propose that these moonlets are formed due to the constructive interference of the gravitationally unstable axisymmetric and nonaxisymmetric perturbations of the self-gravitating Saturnian ring disk. The hydrodynamical slab model of the disk is studied to determine its instability against low-frequency compression-type, or Lin-Shu-type, oscillations whose propagation vector is perpendicular to the axis of the disk's rotation. The linear instability analysis is performed in the following way. First, we derive the general dispersion relation for the gravity perturbations inside the slab within the standard local short-wavelength approach. Next, we match the solutions to the solutions of the Poisson equation outside the slab to arrive at the particular dispersion relation. The particular dispersion relation describes the development of symmetric Jeans' perturbations which cause density enhancements. From this dispersion relation, the growth rate of Jeans-unstable oscillations developing in the spatially homogeneous slab model is obtained. The dispersion relation shows that perturbations of both types, axisymmetric and nonaxisymmetric, are excited simultaneously due to the Jeans' gravitational instability. As a result, circular and spiral patterns develop. We suggest that clumping occurs due to the enhanced density increase at the intersections of the patterns. We also speculate that these clumps further develop into propeller moonlets.

Formation of new alumina by shearing at high pressure

The structures of inorganic solids sheared at high pressure more frequently persist at ambient conditions than those hydrostatically pressurized to high pressure. Accordingly, we can expect to fabricate materials with high-pressure structure to use them for practical purposes at ambient conditions. I, therefore, sheared α-alumina, at gradually heightened pressure up to 18 GPa at room temperature and took transmission X-ray diffraction patterns from the central area of the specimens on imaging plates, one year after the shearing. They showed broad diffused rings. This indicates that the sheared structure is highly disordered. The rings roughly correspond to a highly disordered structure consisting of simple cubic lattices, with the exception of two rings. Alumina with the former structure has not yet been reported. The latter rings correspond to those of alumina above 90 GPa (the structure is unknown). The fact mentioned above suggests the existence of an intermediate state between α-alumina and the alumina above 90 GPa. The above facts also suggest that the transformation mentioned above and the disordering of lattices contributed to plastic deformation of the specimen during the shearing.

Dissipative crystallization of potassium salt of poly(riboadenylic acid)

Dissipative patterns during the course of dryness of aqueous solution of potassium salt of poly(riboadenylic acid) (KPolyA) in the presence of potassium chloride were studied on a cover glass, a watch glass and a glass dish. Accumulation of KPolyA polymers forming the broad ring area and the drastic change in size and shape of the polymer single crystals depending on the location of the dried film, which are the typical effects of the dissipative crystallization, took place. Polymer crystals formed were spherulites, dendritic and rod-like assemblies, which are composed of the single or double helical chains depending on the pH-value of the initial solution.

Drying dissipative structures of thermo-sensitive gel spheres of poly(N-isopropylacrylamide)

Drying dissipative patterns were observed at 25 °C, 33 °C, and 45 °C on a cover glass, a watch glass, and a Petri glass dish during the course of dryness of colloidal crystals of the thermo-sensitive gels of poly(N-isopropylacrylamide) (PNIPA). Two kinds of broad rings, i.e., transparent ring at the outside edge and the ring in the inner area from the edge, were observed. Sizes of the former were the same as those of the initial liquids irrespective of gel concentration, whereas sizes of the latter decreased as gel concentration decreased. These broad rings were composed mainly of the monomeric and the agglomerated gel particles, respectively. Formation of the monodispersed agglomerated particles and their ordered arrays in the inner area of the dried film were observed especially on a Petri glass dish and a watch glass. The important role of the electrical double layers formed around the agglomerated particles is supported for the ordering of the agglomerated particles. The essential differences in the drying patterns between PNIPA gel spheres and the typical colloidal particles did not appear.

Drying dissipative structure of sodium dextran sulfate in aqueous solution

Drying dissipative patterns were observed at room temperature on a cover glass, a watch glass, and a Petri glass dish during the course of dryness of aqueous solution of sodium salts of dextran sulfate (NaDSS) having molecular weights of 5000, 36,000 ~ 50,000 and 500,000. These biopolyelectrolytes are one of the typical polysaccharides. The influences of the hexose units upon the macroscopic and microscopic drying patterns are studied. Formation of some ordered structure is observed for NaDSS in high polymer concentrations especially on a cover glass. Broad ring size decreased as polymer concentration decreased and/or its molecular weight increased. Drying patterns are clarified to be formed by the successive and cooperative pattern formation of convection, sedimentation, and solidification.