Concentric Ring Pattern Research Articles

Various concentric-ring patterns formed in a water-anode glow discharge operated at atmospheric pressure

Pattern formation is a very interesting phenomenon formed above a water anode in atmospheric pressure glow discharge. Up to now, concentric-ring patterns only less than four rings have been observed in experiments. In this work, atmospheric pressure glow discharge above a water anode is conducted to produce diversified concentric-ring patterns. Results indicate that as time elapses, the number of concentric rings increases continuously and up to five rings have been found in the concentric-ring patterns. Moreover, the ring number increases continuously with increasing discharge current. The electrical conductivity of the anode plays an important role in the transition of the concentric patterns due to its positive relation with ionic strength. Hence, the electrical conductivity of the water anode is investigated as a function of time and discharge current. From optical emission spectrum, gas temperature and intensity ratio related with density and temperature of electron have been calculated. The various concentric-ring patterns mentioned above have been simulated at last with an autocatalytic reaction model.

Unprecedented North American snowstorm and East Asian cold wave in January 2016: Critical role of the Arctic atmospheric circulation

AbstractDuring January 21–24, 2016, most land areas in the Northern Hemisphere experienced extreme low temperatures. In North America, a historic snowstorm hit the northern and eastern United States. In East Asia, an unprecedented cold wave occurred and led to record‐breaking low temperatures in many regions. In this study, observational analyses revealed that both extreme events were triggered by a remarkable change in atmospheric circulation in the Arctic region in early January 2016, which switched from a concentric ring pattern to a dipole pattern. The dipole pattern resulted in two inverted Ω‐shaped circulation patterns that dominated the North America and East Asia. The inverted Ω‐shaped circulation patterns induced remarkable tropopause folding, which conveyed high‐potential‐vorticity cold air downwards from the lower stratosphere of Arctic to the middle and lower troposphere of North America, which increased cyclonic vorticity and negative height perturbations, and converged with moist air from the western North Atlantic and Gulf Stream, resulting in a severe snowstorm in the northern and eastern United States from 22 to 24 January. In East Asia, the tropopause folding transported high‐potential‐vorticity cold air downwards to the middle and lower troposphere of East Asia, resulting in the outbreak of a severe cold wave in East Asia from 21 to 24 January.

Photothermocapillary Method for the Nondestructive Testing of Solid Materials and Thin Coatings.

The photothermocapillary (PTC) effect is a deformation of the free surface of a thin liquid layer on a solid material that is caused by the dependence of the coefficient of surface tension on temperature. The PTC effect is highly sensitive to variations in the thermal conductivity of solids, and this is the basis for PTC techniques in the non-destructive testing of solid non-porous materials. These techniques analyze thermal conductivity and detect subsurface defects, evaluate the thickness of thin varnish-and-paint coatings (VPC), and detect air-filled voids between coatings and metal substrates. In this study, the PTC effect was excited by a “pumped” Helium-Neon laser, which provided the monochromatic light source that is required to produce optical interference patterns. The light of a small-diameter laser beam was reflected from a liquid surface, which was contoured by liquid capillary action and variations in the surface tension. A typical contour produces an interference pattern of concentric rings with a bright and wide outer ring. The minimal or maximal diameter of this pattern was designated as the PTC response. The PTC technique was evaluated to monitor the thickness of VPCs on thermally conductive solid materials. The same PTC technique has been used to measure the thickness of air-filled delaminations between a metal substrate and a coating.

Machine learning recognition of vibrational modes in ESPI data

We present a neural network (NN), constructed in Mathematica, that classifies images generated by electronic speckle pattern interferometry (ESPI). The goal of this project was to use the program to identify features in the images representing resonance behavior of the object. Much of our data was collected from unfinished wood surfaces, resulting in only the appearance of nodal lines in our ESPI data rather than the concentric rings that are hallmarks of data from finished instruments. The NN described here was trained to give four different output classifications: no resonant features, concentric ring patterns, clear nodal line patterns, and weak resonance features that correspond to ambiguous features observed at the high and low edges of the resonance band. The NN was trained using a collection of images from scans by an interferometer of multiple wood plates, an aluminium plate, and guitar top plates. In order to improve the accuracy of the classifier, we also explored image filtering techniques to increase the contrast of the images. This NN will eventually automate the process of finding resonant frequencies in real time when scanning new surfaces.

Microdisplacement Measurement Based on F-P Etalon: Processing Method and Experiments.

Herein, a processing method is proposed for accurate microdisplacement measurements from a 2D Fabry–Perot (F-P) fringe pattern. The core of the processing algorithm uses the F-P interference imaging concentric ring pattern to accurately calculate the centre coordinates of the concentric ring. The influencing factors of measurement were analysed, and the basic idea of data processing was provided. In particular, the coordinate rotation by the 45-degree method (CR) was improved; consequently, the virtual pixel interval was reduced by half, and the calculation accuracy of the circle centre coordinate was improved. Experiments were conducted to analyse the influence of the subdivision and circle fitting methods. The results show that the proposed secondary coordinate rotation (SCR) by 45 degrees method can obtain higher accuracy of the centre coordinate than the CR method, and that the multichord averaging method (MCAM) is more suitable for calculation of the centre coordinate than the circular regression method (CRM). Displacement measurement experiments were performed. The results show that the standard experimental deviation of the centre of the circle is approximately 0.009 µm, and the extended uncertainty of the displacement measurement in the range of 5 mm is approximately 0.03 μm. The data processing method studied in this study can be widely used in the field of F-P interferometry.

Interpreting Patterns of Concentric Rings within Small Buoyant River Plumes

High-resolution imagery of small buoyant plumes often reveals an extensive pattern of concentric rings spreading outward from near the discharge point. Recent remote sensing studies of plumes from rivers flowing into the Black Sea propose that such rings are internal waves, which form near a river mouth through an abrupt deceleration of the current, or hydraulic jump. The present study, using numerical simulations, presents an alternative viewpoint in which no hydraulic jump occurs and the rings are not internal waves, but derive instead through shear instability. These two differing dynamical views point to a clear need for additional field studies that combine in-water measurements and time-sequential remote sensing imagery.

Self-agglomerated collagen patterns govern cell behaviour

Reciprocity between cells and their surrounding extracellular matrix is one of the main drivers for cellular function and, in turn, matrix maintenance and remodelling. Unravelling how cells respond to their environment is key in understanding mechanisms of health and disease. In all these examples, matrix anisotropy is an important element, since it can alter the cell shape and fate. In this work, the objective is to develop and exploit easy-to-produce platforms that can be used to study the cellular response to natural proteins assembled into diverse topographical cues. We demonstrate a robust and simple approach to form collagen substrates with different topographies by evaporating droplets of a collagen solution. Upon evaporation of the collagen solution, a stain of collagen is left behind, composed of three regions with a distinct pattern: an isotropic region, a concentric ring pattern, and a radially oriented region. The formation and size of these regions can be controlled by the evaporation rate of the droplet and initial collagen concentration. The patterns form topographical cues inducing a pattern-specific cell (tenocyte) morphology, density, and proliferation. Rapid and cost-effective production of different self-agglomerated collagen topographies and their interfaces enables further study of the cell shape-phenotype relationship in vitro. Substrate topography and in analogy tissue architecture remains a cue that can and will be used to steer and understand cell function in vitro, which in turn can be applied in vivo, e.g. in optimizing tissue engineering applications.

Industrial Structure Transformation and Layout Optimization of Beijing-Tianjin-Hebei Region under Carbon Emission Constraints

To address the issue of global warming, there is a trend towards low-carbon economies in world economic development. China’s rapid economic growth and high carbon energy structure contribute to its large carbon emissions. To achieve sustainable development, China must transform its industrial structure to conserve energy, reduce emissions, and adapt to climate change. This study measured the carbon entropy and carbon emission efficiency of 25 industries in the Beijing-Tianjin-Hebei region from 2000 to 2015 by building carbon entropy models and total factor industrial carbon emission efficiency evaluation models. The study showed that: (a) Priority development industries in the Beijing-Tianjin-Hebei region were expanding, the regional competitiveness of the moderate development industry was improving, and the proportion of restricted development industries had dropped significantly; (b) the spatial distribution of the three types of industries presented a pattern of concentric rings, with priority industries at the core, surrounded by moderate, then by restricted development industries; (c) the status of medium- and high-efficiency industries had improved, while the status of low-efficiency industries had decreased. Spatially, high- and low-efficiency industries were becoming concentrated, and medium-efficiency industries were becoming dispersed; (d) considering carbon entropy and carbon emission efficiency, the path of industrial structure transformation and upgrading and layout optimization in Beijing-Tianjin-Hebei region was proposed.

Self-assembly of concentric microrings of tubule and platy nanoclays for cell patterning and capturing

Self-assembly of nanoparticles has become a valuable tool for creation of various nano-textured materials for biomedicine, electronics, optics, photonics and biotechnology. In this paper, polystyrene sulfonate (PSS) modified tubular and platy nanoclays were used for fabrication of concentric ring patterns on solid surfaces based on "coffee-ring" effect. The technique of nanoclay self-assembly into concentric structures described in this paper does not require special equipment and the self-assembly process is rather fast (1-2 h). Two different molds (a metal sphere and a glass pyramid) fixed in close proximity above a cover glass were used for creating confined geometries necessary to control the process of clay suspension evaporation. The resulting concentric patterns were applied for orienting the growth of human skin fibroblasts and capturing cancer and protozoan cells. The concentric structures formed using HNT-PSS suspension and the pyramid were more effective in directing the growth of fibroblasts, while HNT-PSS and KNP-PSS coatings formed by the sphere fitted better for cell capturing.

Ring-Patterned Perovskite Single Crystals Fabricated by the Combination of Rigid and Flexible Templates.

Regular microstructures can improve the electrical and optical characteristics of perovskite single crystals because of the removal of defects and grain boundaries. Microstructured single crystals are commonly fabricated by either rigid or flexible templates. However, rigid templates usually need surface treatment before crystal fabrication to create an antiadhesion layer, while flexible templates encounter difficulties in achieving a large area of uniform single crystals without any deformation. In this work, we present a facile and robust method to fabricate perovskite single crystals using rigid silicon pillars coated with flexible polymer solutions, in which surface treatment is avoided in the preparation process, and deformation is absent in the formed crystals. The method realized the fabrication of colorful concentric-ring patterns composed of nanoscale single crystals for the first time. In order to concisely control the preparation of the template, the Newton's ring phenomenon was used to value the droplet height because the number of rings changed with the optical path difference. A related digital simulation was performed to find the correlation of the Newton's ring pattern with the shape of the droplets. The simulated results were consistent with the experimental observations generally, indicating that the pattern could be controlled mechanically. Concomitantly, the resulting perovskite nanoscale single crystals formed a regular colorful concentric-ring pattern. By changing the design of the rigid templates, the parameters of the fabrication process, or the selection of the coating polymer solution, different ring-patterned single crystals were successfully prepared without surface treatment and deformation. The crystals have potential applications in lasers or photodetectors.

First Report of Colletotrichum siamense Causing Leaf Anthracnose on Cotton in India

HomePlant DiseaseVol. 104, No. 7First Report of Colletotrichum siamense Causing Leaf Anthracnose on Cotton in India PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Colletotrichum siamense Causing Leaf Anthracnose on Cotton in IndiaV. N. Salunkhe, S. P. Gawande, N. Gokte-Narkhedkar, D. T. Nagrale, N. S. Hiremani, and V. N. WaghmareV. N. Salunkhe†Corresponding author: V. N. Salunkhe; E-mail Address: vanita.salunkhe@icar.gov.inhttp://orcid.org/0000-0003-3123-5534ICAR-Central Institute for Cotton Research, Nagpur 440010, Maharashtra, IndiaSearch for more papers by this author, S. P. GawandeICAR-Central Institute for Cotton Research, Nagpur 440010, Maharashtra, IndiaSearch for more papers by this author, N. Gokte-NarkhedkarICAR-Central Institute for Cotton Research, Nagpur 440010, Maharashtra, IndiaSearch for more papers by this author, D. T. NagraleICAR-Central Institute for Cotton Research, Nagpur 440010, Maharashtra, IndiaSearch for more papers by this author, N. S. HiremaniICAR-Central Institute for Cotton Research, Nagpur 440010, Maharashtra, IndiaSearch for more papers by this author, and V. N. WaghmareICAR-Central Institute for Cotton Research, Nagpur 440010, Maharashtra, IndiaSearch for more papers by this author AffiliationsAuthors and Affiliations V. N. Salunkhe † S. P. Gawande N. Gokte-Narkhedkar D. T. Nagrale N. S. Hiremani V. N. Waghmare ICAR-Central Institute for Cotton Research, Nagpur 440010, Maharashtra, India Published Online:12 May 2020https://doi.org/10.1094/PDIS-09-19-1992-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat During 2017 and 2018, distinct leaf anthracnose symptoms were observed on cotton (Gossypium hirsutum L.) from Wardha district, Maharashtra state, India. The appearance of symptoms coincided with greater humidity and intermittent rains during the months of August and September. Among 500 Bollgard-II cotton hybrids plants, nearly 20 to 30% were found affected, which showed 35 to 40% disease severity. Symptoms initially appeared as small, circular or irregular, sunken, chlorotic spots, which later turned brown with a dark border. As the disease progressed, lesions expanded and merged, causing necrosis of the whole leaf. For pathogen isolation, 15 randomly sampled symptomatic plants were brought to the laboratory. Diseased leaf sections (5 mm2) were surface disinfested with 1% NaClO for 2 min, rinsed three times in sterile water, dried with sterilized blotter paper, and then plated on potato dextrose agar. The plates were incubated at 25 ± 2°C for 5 days under a 12-h photoperiod. Three isolates (CS1, CS2, and CS3) were recovered from infected leaves. Purified colonies were initially white, turned gray with time, and had salmon-colored conidial masses embedded in the medium in a concentric ring pattern and black acervuli aggregated mainly in the center of the culture plate. Conidia were single celled, hyaline, cylindrical having rounded ends, smooth walls, guttulate, 9.6 to 16.9 µm in length, and 3.5 to 6.0 µm in width (n = 100). These morphological characteristics were consistent with the species description of Colletotrichum gloeosporioides complex (Weir et al. 2012). For molecular identification, the internal transcribed spacer (ITS) region of rDNA and a partial sequence of the actin (ACT) and beta-tubulin (TUB2) genes of three isolates were amplified with ITS1/ITS4, ACT-512F/ACT-783R, and BT2Fd/BT4R primers, respectively (Damm et al. 2009). The ITS sequence (MH478170, 558 bp), ACT gene (MH494078, 283 bp), and TUB2 gene (MH494079, 321 bp) of representative isolate CS1 showed 99 to 100% identity with sequences (JX010171, FJ907423, and JX010404, respectively) obtained from the holotype isolate (BPD-I2) of Colletotrichum siamense Prihastuti, L. Cai & K.D. Hyde (Prihastuti et al. 2009; Weir et al. 2012). Pathogenicity was tested on 45-day-old Bollgard-II cotton hybrid plants by spore spray inoculation. Five plants for each isolate were inoculated with a conidial suspension (106 conidia/ml) (and control plants with sterilized water) and kept separately in a glass house at 25°C, >85% relative humidity, and a 12-h photoperiod. Plants were sprayed lightly with water in the morning and evening to maintain humidity and thus enhance the infection. The experiment was repeated. Anthracnose symptoms were observed 7 days after inoculation, whereas the control plants remained symptomless. The pathogen was reisolated from infected leaves and its identity as C. siamense confirmed based on morphological characteristics as well as on sequences of ITS, ACT, and TUB2 genes. To our knowledge, this is the first report of leaf anthracnose caused by C. siamense on cotton in India or globally. This report will be useful to plan for species-specific disease management strategies.The author(s) declare no conflict of interest.

ABERRATIONAL PATTERN DURING THE SELF-ACTION OF THE ТЕМ01 MODE OF LIGHT RADIATION IN NEMATIC LIQUID CRYSTALS

Abstract—The properties of the aberrational pattern resulting from the self-action of the light radiation mode TEM01 in liquid-crystal systems are studied. It is found that the interference of light rays corresponding to two peaks of intensity and nonlinear phase shift leads to the formation of a system of fringes in the Fraunhofer region; their angular period is controlled by the distance between peaks. These fringes fill the entire aberrational pattern (concentric ring pattern) or only its part, depending on the type of the profile of the light-induced phase shift. The possibilities of using the properties of the aberrational pattern in the TEM01 mode for studying the light-induced reorientation of the nematic liquid crystal director are shown.

Contact Line and Adhesion Force of Droplets on Concentric Ring-Textured Hydrophobic Surfaces.

Advances made in fabrication of patterned surfaces with well-defined dimensions of topographic features and their lateral dissemination drive the progress in interpretation of liquid spreading, adhesion, and retreat on engineered solid surfaces. Despite extensive studies on liquid droplet spreading and adhesion on textured surfaces in recent years, conformation of the three-phase contact line and its effect on macroscopic contact angle and droplet adhesion remain the focus of intensive debate. Here, we investigate the effect of surface topography on the adhesion force of Cassie-Baxter-state droplets on concentric ring-textured hydrophobic surfaces having rings with lateral dimensions of 5, 10, and 45 μm and separated by 5, 6, and 7 μm trenches, respectively, with fixed depth of 15 μm. Unlike mostly tested surfaces textured with straight ridges, pores, and pillars, where the droplet base contact line is anisotropic and its conformation varies along the apparent boundary, concentric rings are symmetrical and reinforce the microscopic contact line to align to a circular one that reflects the shape of the pattern. In this study, adhesion forces were calculated based on surface tension and Laplace pressure forces and were compared with the experimental forces for both water and ethylene glycol droplets having a varying contact diameter on the concentric ring-pattern at the point of maximum adhesion force. Results show that the microscopic contact line of the liquid retains its circular shape controlled by circular rings of the pattern, irrespectively of the droplet base diameter larger than 0.8 mm, and there is a good agreement between the experimental and calculated adhesion forces.

Decaying localized structures beyond Turing space in an activator–inhibitor system

We perform numerical simulations beyond Turing space in an activator–inhibitor system involving quadratic and cubic nonlinearities . We show that while all the three fixed points of the system are stable nodes, it exhibits spatially stable patterns as diverse as labyrinths, worms, negatons, and combination of them. The transition among the patterns is found to be dependent on the relative strength (h) of quadratic and cubic couplings. The labyrinths and worms are formed for small values of h while stable negatons are obtained for $$0.0891\le h\le 0.1106$$. The negatons start showing decaying behavior for $$h\ge 0.1135$$ and, finally they vanish at random positions by emitting remnant solitary waves, yielding a pattern of stable concentric rings. The spatial extension of the concentric rings is found to depend on the initial concentration profile of the decaying negatons. The resulting concentric rings do not decay further due to limitation of numerical precision. We also find that the transient period for each pattern also depends on h.

Study of the optical properties of Zn doped Mn spinel ferrite nanocrystals shows multiple emission peaks in the visible range –a promising soft ferrite nanomaterial for deep blue LED

Here, in this report, chemical co-precipitation method has been used for the synthesis of zinc doped manganese spinel ferrite nanocrystals, having the chemical formula of Mn0.5Zn0.5Fe2O4. The structural and morphological analysis have been carried out using X-ray diffraction (XRD) analysis and High Resolution Transmission Microscope (HRTEM). XRD analysis has revealed the formation of pure phase face centred cubic (FCC) spinel ferrite nanocrystals with the average size of 28 nm approximately. Electron Microscopic images show the spherical morphology of the prepared ferrite nanocrystals and the average size obtained from these observation matches well with that from XRD result. Further, Selected Area Diffraction Pattern (SAED) of the prepared nanocrystals gives the combined pattern of concentric rings and sharp bright spots over the rings, which indicates the polycrystalline nature of the sample. Again, elemental analysis of the nanocrystals has been studied by Energy dispersive X-ray spectroscopy (EDX). Ultraviolet–Visible (UV–Vis) spectroscopy measurement shows an absorption peak in the visible range at around 346 nm. From the absorption data, the optical band gap energy has been calculated using Tauc’s plot, which is found to be approximately 3.47 eV. Similarly, UV–Vis diffuse reflectance spectra (DRS) also provide almost the same band gap, following Kubelka–Munk function. Luminescence spectra gives three sharp emission peaks in the visible range at 409 nm, 430 nm and 460 nm of wavelength, on exciting the samples with 350 nm and the intensity of the peaks has been found to decrease on exciting again the sample with 380 nm and 400 nm respectively. In addition, Commission Internationale de L’Eclairage (CIE) diagram shows that this sample can act as a blue light emitting diode (LED). Vibrating Sample Magnetometer (VSM) shows the superparamagnetic nature of the prepared sample and hence, Mn0.5Zn0.5Fe2O4 nanocrystals can be used as a soft ferrite substance and it’s interesting optical properties make it a more technologically applicable nanocrystals.

Influence of nitrogen impurities on the characteristics of a patterned helium dielectric barrier discharge at atmospheric pressure

In this paper, a two-dimensional axisymmetric fluid model was established to investigate the influence of nitrogen impurity content on the discharge pattern and the relevant discharge characteristics in an atmosphere pressure helium dielectric barrier discharge (DBD). The results indicated that when the nitrogen content was increased from 1 to 100 ppm, the discharge pattern evolved from a concentric-ring pattern into a uniform pattern, and then returned to the concentric-ring pattern. In this process, the discharge mode at the current peak moment transformed from glow mode into Townsend mode, and then returned to glow mode. Further analyses revealed that with the increase of impurity level, the rate of Penning ionization at the pre-ionization stage increased at first and decreased afterwards, resulting in a similar evolution pattern of seed electron level. This evolution trend was believed to be resulted from the competition between the N2 partial pressure and the consumption rate of metastable species. Moreover, the discharge uniformity was found positively correlated with the spatial uniformity of seed electron density as well as the seed electron level. The reason for this correlation was explained by the reduction of radial electric field strength and the promotion of seed electron uniformity as pre-ionization level increases. The results obtained in this work may help better understand the pattern formation mechanism of atmospheric helium DBD under the variation of N2 impurity level, thereby providing a possible means of regulating the discharge performance in practical application scenarios.

Spatially Ordered Poly(3‐hexylthiophene) Fibril Nanostructures via Controlled Evaporative Self‐Assembly

AbstractHierarchically structured, gradient concentric rings of regioregular conjugated polymer, rr‐poly(3‐hexylthiophene) (rr‐P3HT) with randomly or directionally crystallized nanofibrils over large areas are obtained by regulating consecutive “stick‐slip” motions of the three‐phase contact line in a confined geometry consisting of an upper curved sphere surface and a lower flat Si substrate (i.e., sphere‐on‐flat geometry), which leads to an axially symmetric capillary‐bridge (bound solution). Self‐organized concentric P3HT ring patterns result from mediating intermolecular interactions between the polymer molecules, and varying the solvent concentration. More interestingly, from the lower solution concentration “shish‐kebab” like morphologies are observed in between adjacent rings. These unusual, directionally crystallized structures are formed spontaneously parallel to the moving direction of the contact line on solvent evaporation. Subsequently, I–V characteristics of the directionally crystallized and randomly distributed P3HT nanofibrils formed across the electrodes are investigated and compared.

Analyzing housing prices in Shanghai with open data: Amenity, accessibility and urban structure

Skyrocketing housing prices in China's megacities have generated broad concerns. By integrating open data from Lianjia.com, Dianping.com, Mobike.com, and Baidu Map POI, we analyze spatial patterns of apartment prices and their association with local attributes in Shanghai. We find that Shanghai's residential market still has a monocentric structure because of the centralized distribution of public transport facilities and amenities. Hedonic models further confirm that structural attributes, accessibility, as well as public and private service amenities significantly shape the real estate market. These factors also are differentiated so as to form a pattern of concentric rings. In the inner-city and expanded inner-city areas, public service amenities such as parks, schools, hospitals, and banks, as well as private service amenities such as entertainment, shopping, and residential service facilities, boost housing prices. In the suburbs, better access to bike sharing, bus stops, and metro stations are the top preferences for apartment buyers. Our study also indicates that the Chinese government needs to make public and private services more accessible, not only spatially in urban peripheries and villages, but also institutionally to lower income families who cannot afford apartments in expensive neighborhoods.

Temporal and spatial changes of urban impervious surface and its influence on urban ecolo-gical quality: A comparison between Shanghai and New York

The urban spatial expansion has led to the considerable substitution of natural vegetation-dominated land surfaces by impervious surfaces, especially in large cities, with great impacts on urban ecological quality. Two most heavily populated cities, Shanghai of China and New York of USA, were chosen as the study cases. Based on Landsat images obtained in 1989, 2002, 2015 in Shanghai and in 1991, 2001, 2015 in New York, normalized difference impervious surface index (NDISI) was used to extract impervious surface (IS) information. The remote sensing based ecolo-gical index (RSEI) was then applied to evaluate the changes of urban ecological quality caused by the increased impervious surface. Furthermore, landscape pattern indices were used to analyze the differences of spatial structure of impervious surface between Shanghai and New York and their influences on urban ecological quality. The results showed a significant difference in urban expansion rate and pattern between Shanghai and New York from the early 1990s to 2015. The IS expansion area in Shanghai was 17.4 times as much as that in New York. The annual IS increase rate of Shanghai was 62.2 times as much as that of New York. Shanghai had experienced an expansion from urban center to the surrounding countryside in a concentric ring pattern, whereas New York showed no much expansion but had IS increase mainly within the inner city through space filling pattern. These differences in IS change rate and spatial distribution pattern had resulted in the difference in urban ecological quality of the two cities. The mean RSEI in Shanghai dropped from 0.717 in 1989 to 0.453 in 2015, with a decrease of 36.8%. In contrast, the RSEI of New York had a decline of 6.9% from 0.552 in 1991 to 0.514 in 2015. The poor ecological condition urban area tended to have large IS patches that were well connected and aggregated.

Hybrid Materials with Controlled Precipitation Pattern of Nanoparticles

Hybrid materials with ordered patterns are important to control their functionality. Such ordered structure can be spontaneously formed in nature by self-organization under far from equilibrium, where energies or substances within the system is always dissipated (dS / dt ≠ 0). Although formation mechanism of self-organized patterns in nature are complex and hard to control, development of various materials that mimic self-organization in nature (e.g. bio-mimetics and bio-inspired) have been developed remarkably in recent years. Formation of various patterned structures with useful function by self-organization lead to further development of material chemistry based on mimic of these structures. In the present study, we focused on Liesegang pattern found by R. E. Liesegang in 1896. Liesegang pattern has gained a lot of interests due to several features; simple procedure of the pattern formation, diversity of the pattern morphology and no selection of materials. In fact, Liesegang pattern can be formed by contact between a gel containing an inner electrolyte and an aqueous solution containing an outer electrolyte. Thus, the formed patters consisted of precipitates which is a reaction product between inner and outer electrolytes, has spatial periodicity with geometric series formulated by spacing law (xn +1/xn = 1+p), where xn +1, xn , and p are the position of two consecutive (n+1st and n th) bands measured from the junction point of the electrolytes and spacing coefficient, respectively. Therefore, Liesegang pattern can be applied for patterning technologies because periodic patterns are easily formed. However, control of the periodicity in Liesegang pattern has not been achieved for a long time. Therefore, it is necessary to control periodicity to apply patterning technologies in micro-nanotechnologies. For this purpose, we examined the influence of experimental parameters on the geometry of pattern formation. We focused on the nucleation rate as one of the parameter, whose effect on the pattern formation has not been clarified yet. In this study, we applied the strategy of surface chemistry to control the nucleation rate. Liesegang pattern formation was discussed based on the nucleation and growth model, where the particle is produced through the production of nuclei (solid state) by nucleation of a certain precursors (molecular state) and the growth of nuclei. To occur the nucleation process, it is necessary to bring the energy state in this system unstable to exceed the energy barrier (ΔG). To achieve this process, the concentration of the precursor should exceed the nucleation threshold (C*). Therefore, ΔG governs the nucleation rate and can be considered C* in the model. can be reduced by the coordination of an appropriate ligand for the decrease of surface free energy. Cysteine was used as the ligand for Agn nuclei and/or Ag nanoparticles in the present system to reduce their surface free energy and thus ΔG. In the system without cysteine, the periodic concentric ring pattern (Liesegang pattern) with the interring distance of about 100−200 μm was formed (Figure 1a), where the interring distance increased further away from the edge of agarose stamp. On the other hand, in the system with cysteine, the periodic concentric ring pattern (Liesegang pattern) with the interring spacing of below 100 μm was formed (Figure 1b), meaning that the ring periodicity was almost half that of the pattern formed without cysteine. Thus, the addition of cysteine that is corresponding to the decrease of induced the Liesegang pattern with the finer periodic structures. To prove this relationship between the decrease ofΔG and the finer structures, we used reaction-diffusion simulation with lowered C*. As a result, Liesegang pattern became finer with the lowering C*. Furthermore, to demonstrate the effect of the lowering and C* on a miniaturization of Liesegang pattern in more detail, we compared the spacing coefficient as a measure of the periodicity of patterns. As a result, both lowering and C* gave smaller spacing coefficient (i.e., finer periodic patterns) (Figure 2). Therefore, it was suggested that the lowering induced the lowering C*. Then, the smaller spacing coefficient at lowered C* was discussed in terms of a slower rate of Ostwald ripening. Similar control of C* through surface chemistry can be applied to various precipitation systems to control the periodicity in these systems. In his study, we propose that the approach based on the surface chemistry enable us to control the periodicity of Liesegang patterns by the controlling C*. Figure 1