High resolution nanoscale chemical analysis of bitumen surface microstructures

Surface microstructures of bitumen are key sites in atmospheric photo-oxidation leading to changes in the mechanical properties and finally resulting in cracking and rutting of the material. Investigations at the nanoscale remain challenging. Conventional combination of optical microscopy and spectroscopy cannot resolve the submicrostructures due to the Abbe restriction. For the first time, we report here respective surface domains, namely catana, peri and para phases, correlated to distinct molecules using combinations of atomic force microscopy with infrared spectroscopy and with correlative time of flight—secondary ion mass spectrometry. Chemical heterogeneities on the surface lead to selective oxidation due to their varying susceptibility to photo-oxidation. It was found, that highly oxidized compounds, are preferentially situated in the para phase, which are mainly asphaltenes, emphasising their high oxidizability. This is an impressive example how chemical visualization allows elucidation of the submicrostructures and explains their response to reactive oxygen species from the atmosphere.

Circuit Analysis of Ionizing Surface Potential Measurements of Electrolyte Solutions

Surface potential measurement values of the gas-liquid interface can be ambiguous despite the numerous electrochemical approaches used for quantification of the reported values. Calibration and normalization methods can be undefined, which often undermines the robustness of the reported values. Surface potential instrumentation and data interpretation also varies significantly across literature. Here, we propose a circuit model for an ionizing surface potential method based on the alpha decay of a radioactive americium-241 electrode. We evaluate the robustness of the circuit model for quantifying the surface potential at the air-aqueous interface. We then show successful validation of our circuit model through determination of the surface tension of the air-electrolyte interface with comparison to respective surface tension literature values. This validation reveals the reliability of surface potential measurements using the americium-241 ionizing method.<br>

Circuit Analysis of Ionizing Surface Potential Measurements of Electrolyte Solutions

Surface potential measurement values of the gas-liquid interface can be ambiguous despite the numerous electrochemical approaches used for quantification of the reported values. Calibration and normalization methods can be undefined, which often undermines the robustness of the reported values. Surface potential instrumentation and data interpretation also varies significantly across literature. Here, we propose a circuit model for an ionizing surface potential method based on the alpha decay of a radioactive americium-241 electrode. We evaluate the robustness of the circuit model for quantifying the surface potential at the air-aqueous interface. We then show successful validation of our circuit model through determination of the surface tension of the air-electrolyte interface with comparison to respective surface tension literature values. This validation reveals the reliability of surface potential measurements using the americium-241 ionizing method.<br>

Estimating badland denudation with pin measurements and high resolution Digital Elevation Models derived from UAV image analysis

&lt;p&gt;The denudation of soil or soft rock surfaces by non-concentrated flow is mostly estimated by relating the&amp;#160;sediment discharge observed at the outlet of a plot or natural micro-catchment to their respective surface&amp;#160;areas. This approach generates an average denudation rate, but ignores spatial patterns of erosion and&amp;#160;deposition. A well established approach to capture such spatial differences are pins, which deliver a highly&amp;#160;precise point measurement of surface elevation change. Advances in the development of Unmanned Aerial&amp;#160;Vehicles (UAVs) and imagine processing in the past decades offer an additional tool for mapping erosion&amp;#160;and deposition at millimetre scale for continuous surfaces. In this study, pin and UAV-derived erosion data&amp;#160;for a badland area in the Karoo rangelands, South Africa, are compared. The results show that typical annual&amp;#160;erosion rates in the study area are lower than the differences between two DEMs generated a year apart.&amp;#160;This illustrates that in situations where erosion rates are low, pins still offer the faster and more reliable&amp;#160;results. For their extrapolation, on the other hand, UAV-derived DEMs provide suitable topographic data.&lt;/p&gt;

Development of a Flex and Stretchy Conductive Cotton Fabric Via Flat Screen Printing of PEDOT:PSS/PDMS Conductive Polymer Composite

In this work, we have successfully produced a conductive and stretchable knitted cotton fabric by screen printing of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and poly(dimethylsiloxane-b-ethylene oxide)(PDMS-b-PEO) conductive polymer composite. It was observed that the mechanical and electrical properties highly depend on the proportion of the polymers, which opens a new window to produce PEDOT:PSS-based conductive fabric with distinctive properties for different application areas. The bending length analysis proved that the flexural rigidity was lower with higher PDMS-b-PEO to PEDOT:PSS ratio while tensile strength was increased. The SEM test showed that the smoothness of the fabric was better when PDMS-b-PEO is added compared to PEDOT:PSS alone. Fabrics with electrical resistance from 24.8 to 90.8 kΩ/sq have been obtained by varying the PDMS-b-PEO to PEDOT:PSS ratio. Moreover, the resistance increased with extension and washing. However, the change in surface resistance drops linearly at higher PDMS-b-PEO to PEDOT:PSS ratio. The conductive fabrics were used to construct textile-based strain, moisture and biopotential sensors depending upon their respective surface resistance.

Treatment of Gaseous Ammonia Emissions Using Date Palm Pits Based Granular Activated Carbon

The present work investigated the application of granular activated carbon (GAC) derived from date palm pits (DPP) agricultural waste for treating gaseous ammonia. Respective findings indicate increased breakthrough time (run time at which 5% of influent ammonia is exiting with the effluent gas) with a decrease in influent ammonia and increase in GAC bed depth. At a gas flow rate of 1.1 L/min and GAC column length of 8 cm, the following breakthrough trend was noted: 1295 min (2.5 ppmv) > 712 min (5 ppmv) > 532 min (7.5 ppmv). A qualitatively similar trend was also noted for the exhaustion time results (run time at which 95% of influent ammonia is exiting with the effluent gas). The Fourier Transform Infrared Spectroscopy (FTIR) findings for the produced GAC indicated some salient functional groups at the produced GAC surface including O–H, C–H, C–O, and S=O groups. Ammonia adsorption was suggested to result from its interaction with the respective surface functional groups via different mechanisms. Comparison with a commercial GAC showed the date palm pits based GAC to be having slightly higher breakthrough and exhaustion capacity.

Analysis Gunshot Residue (GSR) – Reconstruction of Crime Scenes

GSR particles from the surroundings of bullet hole have been characterized as a function of primer type and particle distribution. SEM images were used to verify size and shape of the GSR particles and EDS to verify the elemental composition in a single particle. The same specimens are further subjected toTime of Flight Secondary Ion Mass Spectrometry (ToF SIMS) with a view to identify the respective surface chemistry, molecular nature and molecular mass of the GSR particles. Both inorganic and organic components of GSR in the elemental and combined form can be identified using SIMS.Secondary ion mass spectrum and the image analysis are carried out for selected particles. The mass peaks of oxides of lead, barium and antimony apart from the elemental masses are found. The combination of Pb/Ba/Sb and their oxides in a particular particle specifically establish the characteristics of a typical GSR particle. Molecular imaging and the distribution of the components in the GSR particle before and after sputtering are studied. Lead and its oxide are more concentrated in the surface of the particle compared to Ba and Sb. It is evident that SIMS can detect whether the components are either in the elemental or a compound form or a combination of both. The results of ToF SIMS clearly establish the feasibility of utilizing ToF SIMS as a tool for direct characterization of GSR from environmental polluted particles of the same nature for forensic applications.

Experimental Investigation of Flow Boiling Inside Three Three-Dimensional Surface Enhanced Heat Transfer Tubes

An Experimental investigation was conducted to compare the evaporation characteristics of R410A inside three newly developed horizontal enhanced heat transfer (EHT) tubes with the same OD12.70mm and ID11.50mm, and the result of them are compared with that of a plain tube. The inner enhanced surface of 1EHT tube consists of dimples/protrusions and petal arrays, while that of 2EHT-1 tube and 2EHT-2 tube is composed by longitudinal grooves and dimples of different depths. The mass velocities are in the range of 70kg/m2s-200kg/m2 s with a nominal saturation temperature fixed at 279K and the vapor quality in the test section varies from 0.2∼0.9. As the mass flux increases, both the heat transfer coefficient and pressure penalty increase accordingly. The heat transfer coefficient of EHT tubes can achieve 1.14–1.53 times higher than that of the smooth tube while the pressure gradients is 1.43–1.83 times larger than that of smooth tubes. Besides, the enhancement ratios of all the enhanced surface tubes are larger than their respective surface area ratio, and the enhancement ratio comparisons of heat transfer coefficient are made to obtain the enhancing mechanism. The results show that the EHT tubes appear higher performance at low mass fluxes. In all, the EHT1 tube has the best heat transfer performance at low mass velocity, which can be attributed to its special enhanced inner surface, resulting in the increase of nucleation sites, flow separation and turbulent fluctuations. The other two 2EHT tubes can enhance the evaporation greatly with small respective surface ratios as well as relatively little pressure drop penalty, and them shows outstanding performance especially at high mass velocity.

SPLITTING TERRACED HOUSES INTO SINGLE UNITS USING OBLIQUE AERIAL IMAGERY

This paper introduces a method to subdivide complex building structures like terraced houses into single house units comparable to units available in a cadastral map. 3D line segments are detected with sub-pixel accuracy in traditional vertical true orthomosaics as well as in innovative oblique true orthomosaics and their respective surface models. Hereby high gradient strengths on roofs as well as fac¸ades are taken into account. By investigating the coplanarity and frequencies within a set of 3D line segments, individual cut lines for a building complex are found. The resulting regions ideally describe single houses and thus the object complexity is reduced for subsequent topological, semantical or geometrical considerations. For the chosen study area with 70 buidling outlines a hit rate of 80% for cut lines is achieved.

Evaluation of corrosion resistance of powder coatings after various surface chemical pre-treatment

The surface treatment by a powder coating is one of the progressive technologies. Such coatings are resistant to corrosion and mechanical wearing. The quality of surface protection is affected primarily by a layer pre-treatment, the type of surface tretment, the system selection and the method and quality of application. Taking into account all the surface pre-tretment methods, the chemical pre-modification is a leading method. One of the methods is pre-treatment using a conversion coating which was developed on the nanotechnology basis - BONDRITE NT. That non-phosphate chemical pre-treatment is utilized at a surrounding temperature. It creates nano-ceramic protective layer on steel, zinc and aluminium surfaces, and as the result the coating has a significant adhesion. In the paper, the possibilities for the improvement of corrosion resistance of powder coatings using the subject conversion coating are presented at the current pasivation of respective surface.