Surfaces Coverage Research Articles

Spatio–Temporal Variations in Impervious Surface Patterns during Urban Expansion in a Coastal City: Xiamen, China

Impervious surfaces (IS) coverage is a quantifiable environmental indicator for understanding urban sprawl and its potential impacts on sustainability of urban ecological environments. Numerous studies have previously demonstrated global and regional IS variation, but little attention has been paid to the different internal and external patterns of IS development as urbanization progresses. This study estimates IS coverage in a subtropical coastal area of Xiamen, southeastern China, from Landsat TM/OLI images obtained in 1994, 2000, 2004, 2010, and 2015, and quantifies its spatio–temporal variations using IS change trajectories and radar graphs. During the study period, IS gradually expanded along the shoreline in a pattern resembling the shape of the bay. The land surfaces are classified into four zones: IS1 and IS2, dominated by cultivated land and forest; IS3, complex land use/coverage; and IS4, built-up areas. The progression and transformations of these zones highlight the main trends in IS changes in the study area. The trajectories of the zones form a layered structure in which the urban centers of each district progressively gain IS4, and transformations into IS3 and IS2 extend successively beyond the centers. The orientation of IS expansion in each of the six districts of Xiamen is revealed by radar graphs. The areas containing intermediate and high percentages IS each expanded in generally consistent directions throughout the study period, except in Tong’an district, which showed a change in the direction of expansion of its area of intermediate and high IS.

COMPREHENSIVE EVALUATION OF URBAN SPRAWL ON ECOLOGICAL ENVIRONMENT USING MULTI-SOURCE DATA: A CASE STUDY OF BEIJING

Abstract. With urban population growing and urban sprawling, urban ecological environment problems appear. Study on spatiotemporal characteristics of urban sprawl and its impact on ecological environment is useful for ecological civilization construction. Although a lot of work has been conducted on urban sprawl and its impact on ecological environment, resolution of images to extract urban boundary was relatively coarse and most studies only focused on certain indicators of ecological environment, rather than comprehensive evaluation of urban ecological environmental impact. In this study, high-resolution remote sensing images of Beijing from aerial photography in 2002 and 2013 respectively are employed to extract urban boundary with manual interpretation. Fractional Vegetation Coverage (FVC), Water Density (WD), Impervious Surfaces Coverage (ISC), Net Primary Production (NPP), and Land Surface Temperature (LST) are adopted to represent ecological environment. The ecological environment indicators are measured with some general algorithms by combining Landsat images, GIS data and metrological data of 243 day, 2001 and 244 day, 2013. In order to evaluate the impact of urban sprawl on ecological environment, pseudo changes due to metrological variation and other noise in this time period are removed after images calibration. The impact of urban sprawl on ecological environment is evaluated at different scales of urban extent, Beijing ring road and watershed. Results show that Beijing had been undergoing a rapid urbanization from 2002 to 2013, with urban area increase from 600 square kilometres to 987 square kilometres. All ecological environment indicators except LST became terrible in urban sprawl region, with carbon reduction of approximate 40508 tons. The Beiyun River watershed of Beijing degraded seriously since ISC increased to 0.59. Gratifyingly, ecological environment indicators including NDVI, NPP, and LST inside of 4th Ring Road became well.

COMPREHENSIVE EVALUATION OF URBAN SPRAWL ON ECOLOGICAL ENVIRONMENT USING MULTI-SOURCE DATA: A CASE STUDY OF BEIJING

With urban population growing and urban sprawling, urban ecological environment problems appear. Study on spatiotemporal characteristics of urban sprawl and its impact on ecological environment is useful for ecological civilization construction. Although a lot of work has been conducted on urban sprawl and its impact on ecological environment, resolution of images to extract urban boundary was relatively coarse and most studies only focused on certain indicators of ecological environment, rather than comprehensive evaluation of urban ecological environmental impact. In this study, high-resolution remote sensing images of Beijing from aerial photography in 2002 and 2013 respectively are employed to extract urban boundary with manual interpretation. Fractional Vegetation Coverage (FVC), Water Density (WD), Impervious Surfaces Coverage (ISC), Net Primary Production (NPP), and Land Surface Temperature (LST) are adopted to represent ecological environment. The ecological environment indicators are measured with some general algorithms by combining Landsat images, GIS data and metrological data of 243 day, 2001 and 244 day, 2013. In order to evaluate the impact of urban sprawl on ecological environment, pseudo changes due to metrological variation and other noise in this time period are removed after images calibration. The impact of urban sprawl on ecological environment is evaluated at different scales of urban extent, Beijing ring road and watershed. Results show that Beijing had been undergoing a rapid urbanization from 2002 to 2013, with urban area increase from 600 square kilometres to 987 square kilometres. All ecological environment indicators except LST became terrible in urban sprawl region, with carbon reduction of approximate 40508 tons. The Beiyun River watershed of Beijing degraded seriously since ISC increased to 0.59. Gratifyingly, ecological environment indicators including NDVI, NPP, and LST inside of 4<sup>th</sup> Ring Road became well.

Critical thickness of foam films stabilized by nonionic or ionic surfactants and their mixtures

The critical thickness (hcr) for foam films of n-dodecyl β-D maltoside (C12G2) and of its mixed solutions with dodecanol (C12Е0), hexaethylene glycol dodecyl ether (C12E6) and dodecyl trimethylammonium bromide (C12TAB) of different molar ratios (50:1; 1:1;1:50) at low and high ionic strength was measured interferometrically. It was found that hcr increases with an increase in the film radius, regardless of the solution’s composition. At low ionic strength the type of surfactant influences substantially the value of hcr. At high ionic strength the level of nonionic surfactant does not in fact influence the value of the critical thickness, while the effect of an ionic surfactant may be significant, in accord with its molar ratio in the mixture: (i) C12TAB in the 50:1 molar ratio mixture acts as a minor additive and supports C12G2 in reducing of negative charge; the values of hcr for films from the mixture are lower than those from solution of C12G2 alone; (ii) at a molar ratio 1:1C12TAB has a dominant role, so it recharges the film surfaces and the hcr values of films from the mixture are higher.The measured critical thicknesses hcr(exp) have been juxtaposed with the calculated ones hcr (cal) by the approaches of Vrij, Radoev-Scheludko-Manev (RShM) and Coons. In two of the cases, the experimentally determined drainage coefficient α has been used. The comparison has shown that the combination of RShM equation with α firmly improves the correlation between hcr(exp) and hcr(cal). Good agreement between hcr(exp) and hcr(cal) for films of low surfaces coverage was achieved by introducing an additional, non-DLVO attraction force.

Surface coverage dictates the surface bio-activity of d-amino acid oxidase

This work presents a systematic study on the relationship between the adsorption mechanism and the surface bio-activity of d-amino acid oxidase (pkDAAO). This rational approach is based on measuring the characteristic filling and relaxation times under different experimental conditions. With such a goal, real-time adsorption–desorption experiments at different degrees of surface coverage were performed tuning the electrostatic and hydrophobic interactions by changing the pH condition for the adsorption and the substrate properties (silica or gold). Surface bio-activity was measured in situ by amperometry using the bio-functional surface as the working electrode and ex situ by spectrophotometry. On both solid substrates, pkDAAO adsorption is a transport-controlled process, even under unfavorable electrostatic interactions (charged protein and substrate with the same sign) due to the high percentage of basic amino acids in the enzyme. On silica, the relaxation step is electrostatic in nature and occurs in the same time-scale as filling the surface when the substrate and the enzyme are oppositely charged at low surface coverage. Under unfavorable electrostatic conditions, the relaxation (if any) occurs at long time. Accordingly, the bio-activity of the native pkDAAO is preserved at any surface coverage. On gold, this step is driven by hydrophobic interactions (pH-independent) and the surface bio-activity is highly dependent on the degree of surface coverage. Under these conditions, the surface bio-activity is preserved only at high surfaces coverage. Our results clearly indicate that pkDAAO bio-functionalized surfaces cannot be coupled to amperometry because the analyte interferes the electrochemical signal. However, this simple bio-functionalized strategy can be joined to other detection methods.

Spatio-temporal analysis of urban temperature in Bandung City, Indonesia

This study presents an evaluation of urban micro-climate about the exsistence level urban vegetation, in association with the urban temperature (surface temperature) and urban built-up area of Bandung City. The changes in urban vegetation cover, urban temperature, and urban built-up area observed using Landsat 5 TM and Landsat 7 ETM + bands were evaluated on the basis of the WDRVI (Wide Dynamic Range Vegetation Indices), NDBI (Normalized Difference Built-up Index), and SAVI (Soil-Adjusted Vegetation Index). It was found that, due to the uncontrolled urban growth and the removal of urban vegetation cover and urban green space, there was a significant increase in urban temperature, in NDBI, but a decrease in WDRVI. The maximum urban temperatures, NDBI, and the minimum values of WDRVI indices were established in 2009. Therefore the results indicate a significant effect of higher density of impervious surfaces coverage (urban built-up area) contributing significantly to the increase of urban temperature. Again the results also confirm that urban vegetation landscape coverage in the surrounding of industrial area reduced the urban temperature. Based on the results, we recommend the city government to provide more urban green space by cooperating with private land owner, in order to decrease urban temperature and create a healthier living environment for urban inhabitants.

Neural surfaces coverage with “collagen films and cigarettes”: A revisited and modified method of protection and retraction during microsurgical approaches to craniospinal lesions

Objective Despite the surgical cotton patties application and meticulous manipulation, mechanical contact between the different microsurgical instruments and neurovascular structures may jeopardize its integrity through laceration or cerebrospinal perfusion. We present a technique based on using collagen films and cigarettes, both to protect and retract such structures, and compared it with the cottonoid technique. Materials and methods During the last 3 years, collagen in “film and cigarette format” has been used in several microsurgical procedures for the treatment of craniospinal lesions by the first author. The collagen films were broken into pieces and adapted to the exposed neural surface measurements to protect and/or retract during microsurgical dissection. At the same time, handmade collagen “cigarettes” were used as retractors to keep open the neural lips of the transsulcal and transfissural corridors. To investigate the relevance of this technique for minimizing surgical morbidity, a blind third-party observer quantified the tissue preservation by a postoperative magnetic resonance imaging (MRI) protocol, in a short series with randomized cotton patty vs. collagen film protection. Results Only two of the 20 examined “collagen group” cases exhibited areas of additional abnormal signal, as against 16 cases of the “cotton patty group.” Furthermore, a statistically significant difference between both the groups based on the radiological results was also demonstrated. Conclusion The results of the present series support the usefulness of the neurovascular coverage and retraction with collagen films and cigarettes, respectively. It seems to be a good alternative to surgical cotton patties and other materials owing to its hemostatic, protection, retraction, and dissection capacity.

Chemical Trends in the Electromodulated Infrared Vibrational Spectroscopy of Various Silicon/Electrolyte Interfaces

As part of a continuing effort on the in situ characterization of semiconductor/electrolyte interfaces, we present here a further new set of experimental results on the electromodulated infrared (1.1–5 μm) vibrational spectroscopy of various n‐Si/electrolyte interfaces. The origin, shapes, and positions of the various superimposed vibrational peaks that were earlier observed at the Si/acetonitrile interface (Si‒H, C≡N, and O‒H region) have been clarified using various solvents, anions, and cations. The superposition of the peaks from oxidized Si‒H and C≡N (in acetonitrile electrolyte) near 4.4 μm is clearly resolved by comparison with, e.g., nitromethane solvent. Regarding the O‒H spectrum, comparative experiments with ethylenediamine, tetrahydrofuran, nitromethane, and acetonitrile solvents, tetrabutylammonium perchlorate, tetrafluoroborate, bromide, and chloride solutes, give evidence that three components are involved: (i) adsorbed water (near 3 μm) which appears first upon interface aging, (ii) isolated Si‒O‒H (narrow feature near 2.7 μm), and (iii) hydrogen‐bonded Si‒O‒H (which shifts considerably depending upon the electrolyte). A new central C‒H peak appears at 3.42 μm on gold‐coated surfaces (coverage ∼1 monolayer), in acetonitrile; this can be associated with the interaction of the molecules with the gold‐coated surface. Two essential conclusions of the paper are the following: (i) from an analysis of the phase lag (upon electromodulation) of the surface‐state absorption and of the O‒H vibrational peaks, it is inferred that the surface states lie preferentially at locations on the surface where the O‒H bonds are in the form of Si‒O‒H groups rather than adsorbed water; (ii) all the experiments indicate that the adsorbed can stand for hours on the silicon surface before oxidation takes place.